Chemical engineering education ( Journal Site )

Material Information

Chemical engineering education
Alternate Title:
Abbreviated Title:
Chem. eng. educ.
Physical Description:
v. : ill. ; 22-28 cm.
American Society for Engineering Education -- Chemical Engineering Division
Chemical Engineering Division, American Society for Engineering Education
Place of Publication:
Storrs, Conn
Publication Date:
annual[ former 1960-1961]


Subjects / Keywords:
Chemical engineering -- Study and teaching -- Periodicals   ( lcsh )
periodical   ( marcgt )
serial   ( sobekcm )


Chemical abstracts
Additional Physical Form:
Also issued online.
Dates or Sequential Designation:
1960-June 1964 ; v. 1, no. 1 (Oct. 1965)-
Numbering Peculiarities:
Publication suspended briefly: issue designated v. 1, no. 4 (June 1966) published Nov. 1967.
General Note:
Title from cover.
General Note:
Place of publication varies: Rochester, N.Y., 1965-1967; Gainesville, Fla., 1968-

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
oclc - 01151209
lccn - 70013732
issn - 0009-2479
lcc - TP165 .C18
ddc - 660/.2/071
System ID:

Full Text

che e g i e e du a

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Chemical Engineering Education
Department of Chemical Engineering
University of Florida
Gainesville, FL 32611

Chemical Engineering Education



EDITOR: Ray W. Fahien (904) 392-0857
MANAGING EDITOR:Carole Yocum (904) 392-0861


E. Dendy Sloan, Jr.
Colorado School of Mines

Gary Poehlein
Georgia Institute of Technology

Lee C. Eagleton
Pennsylvania State University

Richard M. Felder
North Carolina State University

Jack R. Hopper
Lamar University

Donald R. Paul
University of Texas

James Fair
University of Texas
J. S. Dranoff
Northwestern University

Frederick H. Shair
California Institute of Technology

Alexis T. Bell
University of California, Berkeley

Angelo J. Perna
New Jersey Institute of Technology

Stuart W. Churchill
University of Pennsylvania

Raymond Baddour
Massachusetts Institute of Technology

Charles Sleicher
University of Washington

Leslie W: Shemilt
McMaster University

Library Representative
Thomas W. Weber
State University of New York



118 Auburn University, Belinda Dickman, Robert P. Chambers


124 A One-Hour Professional Development Course for Chemical
Engineers, MarkE. Orazem, Dinesh O. Shah


132 Introducing the Concept of Film Heat Transfer Coefficients,
Robert Field

148 An Open-Ended Problem in Chemical Reaction Engineering,
Phillip E. Savage

164 Stochastic Modeling of Chemical Process Systems:
Part 3. Applications, R. O. Fox, L. T. Fan


136 A Random Walk in Porous Media, J. L. Duda


145 Drainage of Conical Tanks With Piping, Jude T. Sommerfeld


154 Composite Materials: An Educational Need,
Tony E. Saliba, James A. Snide


130 Meet Your Students: 3. Michelle, Rob, and Art, Richard M. Felder


158 Introducing Applications of Biotechnology to High School
Donald L.Wise, Ralph A. Buonopane, David C. Blackman


168 Plasmid Instability in Batch Cultures of Recombinant Bacteria: A
Laboratory Experiment,
William E. Bentley, Dhinakar S. Kompala

135, 147, 153 Book Reviews

157 BooksReceived

CHEMICAL ENGINEERING EDUCATION (ISSN 0009-2479) is published quarterly by the Chemical Engi
neering Division, American Society for Engineering Education and is edited at the University of Florida. Cor-
respondence regarding editorial matter, circulation, and changes of address should be sent to CEE, Chemical
Engineering Department, University of Florida, Gainesville, FL 32611. Advertising material may be sent directly
to E.O. Painter Printing Co., PO Box 877, DeLeon Springs, FL 32130. Copyright 1990 by the Chemical
Engineering Division, American Society for Engineering Education. The statements and opinions expressed in
this periodical are those of the writers and not necessarily those of the ChE Division, ASEE, which body
assumes no responsibility for them. Defective copies replaced if notified within 120 days of publication. Write for
information on subscription costs and for back copy costs and availability. POSTMASTER: Send address
changes to CEE, Chem. Engineering Dept., University of Florida, Gainesville, FL 32611.




Auburn University
Auburn University, AL 36849-5127

Auburn University is the largest, most compre-
hensive university in Alabama and is the state's
major graduate school for students in engineering,
agriculture, physical and biological sciences, veteri-
nary medicine, and many other areas of study. Dur-
ing the fall quarter of 1989, the College of Engineer-
ing had 3,769 students, placing it among the top
twenty largest colleges of engineering in the nation.
Auburn first offered courses in chemical engi-
neering in 1913, and the first class of MS chemical
engineering graduates received degrees in 1919. The
doctoral program began in 1974 and the professional
mentors program in 1986. Women have been earn-
ing chemical engineering degrees at Auburn since
the early days of the program.
The program at Auburn has consistently at-
tracted large numbers of excellent undergraduates.
In 1989, the chemical engineering department had a
freshman class of 123, the fourth largest in the United

States as measured by the enrollment survey taken
at the 1989 AIChE meeting in San Francisco. A
freshman class of that size translates into a senior
class of about eighty, which is significantly higher
than the expected 1990-91 graduating class of about
Auburn has one of the largest graduate pro-
grams in the Southeast. It experienced dramatic
growth during the 1970s and 1980s and is becoming
a significant program at both the doctoral and the
master's levels. There are twenty-seven new full-
time graduate students as of fall 1990-an increase
from the previous average of twenty new graduate
students per year. Approximately three-quarters of
these new students are earning their PhDs. The
total fall 1990 full-time graduate enrollment is eighty,
and there are fifteen part-time graduate students
working toward a master of chemical engineering
Auburn chemical engineering students are
heavily recruited. Last year, more than 125 compa-
nies interviewed BS, MS, and PhD chemical engi-

@ Copyright ChE Division ASEE 1990


neers through the University Placement Office, and
more companies are expected next year. Employers
respect and recruit Auburn graduates for their strong
work ethic, high standards, and high levels of moti-
Auburn has a history of student excellence.
The high quality of entering freshmen at Auburn
(with average ACT scores of 27.1 and average SAT
scores of 1202) has consistently ranked the depart-
ment at or near the top of Southeastern public uni-
versity chemical engineering departments. Similarly,
the quality of graduate students is high, with the
average GRE quantitative score above 750 (out of
800). The proportion of women in the undergraduate
program has risen significantly during the past dec-
ade. Minority enrollment is small, but growing; about
ten percent of the undergraduates are black.
Both the graduate and the research programs
have shown impressive growth, with the total value
of extramural research continually exceeding five
million dollars. Annual research expenditures were
$2.5 million in 1988-89, with approximately eighty
percent coming from federal agencies.
The department has had seven NSF grants in
the past three years. As reported in the 1989 Ameri-
can Chemical Society Directory of Graduate Research,
our department published 103 refereed articles in
1987-88, which ranks Auburn 16th among public
chemical engineering departments in the United
States. Refereed publications for this year will be
significantly more than in 1988.
The department received the Dow Outstanding
Chemical Engineering Department Award each year
since 1983. We also were awarded the Exxon Cen-
tennial Outstanding Chemical Engineering Depart-
ment Award for the years 1984-1990.
The department is principally located in Ross
Hall, with additional research, lab, teaching, and
office spaces in several nearby buildings. Currently,
the department has thirty-one research or teaching
laboratories. Tennessee Eastman recently invested
a substantial amount in our undergraduate labora-
tories, allowing us to begin upgrading and improv-
ing the facilities.
Prominent research centers which Auburn di-
rects include the Space Power Institute (SPI), the
Consortium for Commercial Applications of Space,
the Pulp and Paper Research and Educational Cen-
ter, the Molecular Genetics and Biotechnology Cen-
ter, the Advanced Manufacturing Technology Cen-
ter, the National Center for Asphalt Technology, the

Alabama Microelectronics Science and Technology
Center, the Highway Research Center, and the Wa-
ter Resources Research Institute.
The Space Power Institute and the Consortium
for Commercial Applications of Space, which con-
duct space-related research programs, were estab-
lished as the academic focus for the nation's space
power program. Auburn is the lead university in a
multi-university consortia funded by NASA and other
federal agencies. Terry Baker and Bruce Tatarchuk

The program at Auburn has consistently
attracted large numbers of excellent
undergraduates. In 1989, the
department had a freshman
class of 123.

are heavily involved with Auburn's space research.
In recognition of its contributions to space research,
NASA designated Auburn as a Space Grant Univer-
At the request of pulp and paper industry lead-
ers, the college of engineering established the Pulp
and Paper Research and Educational Center
(PPREC) in 1985. Industry leaders felt Auburn's sig-
nificant contributions to the industry and its loca-
tion in the heart of the pulp and paper manufactur-
ing area made it the ideal university to direct the
project. The goal of PPREC is to conduct research on
improving productivity and profitability in the in-
dustry, to provide highly-skilled engineers, to fur-
ther the application of science and advanced tech-
nology in the industry by conducting'rundamental
applied research with emphasis on quality and cost
efficiency, to be a continuing educational resource
for the industry, and to provide a facility for develop-
mental activities in pulp and paper manufacture.
The PPREC is one of the leading paper research and
educational centers in the South. A. Krishnagopalan
is the acting director of PPREC and coordinator of
the Pulp and Paper Instructional Program in chemi-
cal engineering.


The undergraduate curriculum approved for
1991 consists of 204 quarter hours: 82 in chemical
engineering, 39 in chemistry, 23 in mathematics, 8
in physics, 3 in engineering science, and 46 in liberal
arts, humanities, and social sciences. Chemical engi-
neering courses in the basic curriculum include mass
and energy balances, thermodynamics, computers in

Auburn has one of the largest graduate programs in the Southeast, It experienced
dramatic growth during the 1970s and 1980s and is becoming a significant program at both the
doctoral and the master's levels. There are twenty-seven new full-time graduate students as of fall 1990 ....
Approximately three-quarters of these new students are earning their PhDs.

chemical engineering, fluid mechanics, heat and mass
transfer, stagewise operations, reaction engineering,
process design practice, computer-aided process de-
sign, process dynamics, digital process control, proc-
ess economics, computer-aided process simulation,
and hazardous materials management.
For students who wish to pursue special inter-
ests, the department offers options in biochemical
engineering, computer-aided design and control,
environmental chemical engineering, pulp and pa-
per engineering, and pre-medicine/pre-dentistry.
These options offer electives appropriate to each area
plus electives in advanced materials. Students take
an intensive series of laboratory courses that in-
cludes transport and thermodynamics, stagewise op-
erations, computer-aided process control, process
simulation, process design, pulp and paper engineer-
ing, surface and colloid science, senior projects, and
undergraduate research. The program features
numerous projects in the senior year that build upon
knowledge gained in previous years' study.
The Doctor of Philosophy and the Master of
Science degree programs are based on strong chemi-
cal engineering fundamentals, specialized courses,
and research. Research opportunities are frequently
interdisciplinary and include collaborative research
in chemistry, materials engineering, electrical engi-
neering, forestry, microbiology and genetics,
pharmacy, etc. Core courses for the Master's degree
program include transport phenomena, chemical
engineering analysis, chemical engineering thermo-
dynamics, and reaction engineering. Elective courses,
directed reading, special topics, seminars, and a the-
sis complete the program.
For the PhD degree, students must complete
the MS core courses plus advanced courses in nu-
merical methods, process control, and catalysis. They
must also complete the requirements of a minor,
consisting of a series of courses outside of chemical
engineering. The heart of the PhD program is a dis-
sertation describing the student's original research.
The Master of Chemical Engineering Degree is
a professionally oriented non-thesis degree designed
for working chemical engineers to allow them to
update and broaden their knowledge of the field.

Bob Himes sets up the Langmuir-Blodgett deposition


The department has a broad and varied re-
search focus, and most faculty members perform
research in more than one area (see Table 1). BRUCE
TARTARCHUK conducts research in catalysis and
microscopic surface interactions occurring at and
between solid surfaces. As part of his research, he
measures fundamental surface properties using state-
of-the-art spectroscopic probes. The spectroscopic
probes permit the measurement of reaction, adsorp-
tion/desorption phenomena, molecular vibration and
structure, and non-destructive depth-profiling of
reactions at buried interfaces. Since two materials
always contact at an interface or a surface measure-
ment, understanding and control of these phenom-
ena provide a powerful means to control surface
reaction phenomena. Tatarchuk's research has ap-
plication to the study and improvement of heteroge-
neous catalysis, thin film protective coatings, thin
film solid lubricants, and new generation high en-
ergy density and high power density composite fi-
brous electrode material.


Faculty and Research Interests
a Terry K. Baker University of Wales
Heterogeneous Catalysis Chemical Engineering of Composites
Heterogeneous Carbon Controlled Atmosphere Electron
a Robert P. Chambers University of California
Biochemical Engineering Biomedical Engineering Pulp and
Paper Engineering Environmental Engineering
a Christine W. Curtis Florida State University
Asphalt Chemistry Catalysis Coal Science and Conversion *
Reaction Pathways
a Mahmoud El-Halwagi UCLA
Process Design Optimization Process Control
o James A. Guin University of Texas
Transport Phenomena Catalysis Coal Science and Conversion
Mass and Heat Transport Reaction Kinetics and Engineering
Engineering of Asphalt/Aggregate Composites
a A. Krishnagopalan University of Maine
Reaction Kinetics and Engineering Pulp and PaperEngineering
Process Instrumentation Process Control
a Jay H. Lee California Institute of Technology
Process Control
o Y. Y. Lee Iowa State University
Biochemical Engineering Biotechnology Biomass and Pulp
and Paper Engineering Reaction Kinetics and Engineering
a Glennon W. Maples Oklahoma State University
Combustion Energy Conversion and Use Thermodynamics *
Utility Systems
a Ronald D. Neuman The Institute of Paper Chemistry
Interfacial Phenomena Pulp and Paper Engineering Solvent
Extraction Surface and Colloid Science
a Timothy D. Placek University of Kentucky
Optimization Process Simulation Pulp and Paper Engineering
a C. William Roos Washington University
Biochemical Engineering Biotechnology
a Arthur R. Tarrer Purdue University
Environmental Engineering Catalysis Coal Science and
Conversion Mass and Heat Transfer Process Control Reac-
tion Kinetics and Engineering Engineering of Asphalt/Aggre-
gate Composites
a Bruce J. Tatarchuk University of Wisconsin
Catalysis Chemical Engineering of Space Systems Reaction
Kinetics and Engineering Surface Science Materials Science
Part-Time, Visiting, andAdjunctFaculty
a George Emert Adjunct Auburn University Executive Vice
President (Virginia Tech) Biotechnology Biomass Applied
a David Hart Adjunct of Rust Engineering (University of Ala-
bama) Process Design Plant Design
SJamesP.Henley Visiting (University of Mississippi) Application
of Expert Systems to Process Control
a Leo J. Hirth Part-Time (University of Texas at Austin) Process
Simulation and Design
a Donald Vives Part-Time (Columbia University) Thermodynamics
a David Whitman Visiting (Auburn University) Biomedical Engi-


TERRY BAKER performs research in com-
posite materials, gasification/protection of carbona-
ceous materials, carbon filaments in energy storage
devices, fundamental aspects of catalytic carbon for-
mation, carbon deposition of metal catalysts, metal
support interactions, and physical and chemical prop-
erties of small particles. His research in composite
materials will have application to such things as
production of a three-dimensional preform for use in
automotive and aerospace structures. As part of his
research with SPI, Baker is investigating the use of
carbon composites in aerospace applications where
materials are expected to survive and maintain their
integrity in a variety of hostile conditions. He is also
examining the use of carbon as electrode material in
capacitors. In his metal support interactions research,
he is studying ways of tailoring the structure of cata-
lysts to control the pathways so that the yield of a
desired product from a given reaction can be maxi-

RONALD NEUMAN conducts research in sur-
face and colloid science. Currently, he is studying
monolayers, or monomolecular films, which can be
used to model various interfacial systems and proc-
esses. Monolayer studies are important because
physical, chemical, and biochemical process rates
often are affected by materials, such as surfactants
or surface-active agents, that concentrate at phase
boundaries. By studying monolayers, Neuman can
extrapolate information about interfacial behavior
and interactions of surface-active molecules. Mono-
layers permit him to perform experiments on a well-
defined controlled interfacial system. His unique ap-
proach to the study of monolayers or monomolecular
films is his use of laser techniques. He is developing
and applying advanced laser techniques to monolay-
ers at fluid/fluid interfaces. Progress in obtaining
fundamental information in classical surface chemi-
cal approaches has become more difficult, but Neu-
man eliminates this difficulty with the use of sophis-
ticated, recently-developed laser techniques. These
techniques hold promise for significant advancement
in understanding the molecular processes underly-
ing interfacial phenomena and systems. Neuman is
also measuring the thermodynamics and transport
properties of surface films. His research will have
applications to solvent extraction, membrane tech-
nology, food emulsion technology, and papermaking.

A. KRISHNAGOPALAN is the primary re-
searcher in the pulp and paper area. His research
explores ways of increasing productivity and profita-
bility in the industry. His major interests lie in
computer-aided process control, advanced pulping

and bleaching technologies, paper coatings, and
composite materials. He also hopes to develop an
improved kraft digester control method. His new
control approach will reduce errors caused by feedfor-
ward predictors and will allow the effect of certain
process disturbances to be estimated and counter-
acted. He hopes to apply this type of controller to a
large digester.
Computer-aided process simulation is the focal
point of TIMOTHY PLACEK's research. He is de-
veloping an Advanced Simulator for the Pulp and
Paper Industry (ASPPI) to assist the engineer in de-
cision-making and to increase efficiency in the in-
dustry. Placek decided to develop ASPPI in response
to a lack of state-of-the-art technology in computer
capability in modeling paper mills and pulp mills.
Current software was developed for mainframe com-
puters and does not translate well to the new micro-
computers in use today. ASPPI's user interface al-
lows the engineer to use mice and pointing devices
on the screen to "blend" into and become part of the
simulated process. It is also more user-friendly than
other software on the market. It uses process termi-
nology to represent specific areas; the engineer is
allowed to use a name of his choice, such as the
actual name of the piece of equipment. It also de-
tects errors made during data entry, as opposed to
the current software programs where the engineer
must spot the errors after completion of simulation.
ASPPI will give the engineer more complete control
of the process, eliminate costly errors, and save time.
Christine Curtis, James Guin, and Arthur
Tarrer are the principal investigators in coal sci-
ence, energy conversion, and asphalt adhesion and
absorption. CHRISTINE CURTIS works with
NCAT to examine the causes of asphalt deteriora-
tion on highways and is studying asphalt adhesion
in particular. She hopes to determine what part of
the asphalt adheres to the rock, and once she identi-
fies the components that adhere, she can modify,
improve, and promote the adhesion process. She also
hopes to modify the surface of the aggregate to in-
crease the adhesion of the asphalt so the adverse
affects of certain weathering conditions can be mini-
mized. Curtis is also performing coal coprocessing
research. She explores how hydrogen in solvent af-
fects the coprocessing results. Through a model sys-
tems approach, she examines the fundamental chem-
istry involved in high temperature and pressures of
coprocessing. With an actual systems approach, she
changes the chemistry of the resid by catalytically
reacting and pre-treating it to make the hydrogen-

Peter Lloyd (L) and Meenakshi Swaminathan check a
specimen in the secondary ion mass spectrometer.

rich material more suitable for coal solvation. She
hopes to improve the resid's ability to solvate coal
and to transfer hydrogen to coal. She is studying
model systems and exploring the interactions of vari-
ous components in coal and resid on the molecular
level in the presence of a catalyst.
JAMES GUIN's research applies transport phe-
nomena and reaction engineering to the develop-
ment of improved catalysts for coal and petroleum
processing. Guin wants to learn more about the dif-
fusion of large molecules in small pores of catalysts
and membranes and to develop catalysts with im-
proved pore size distribution for coal liquefaction.
These catalysts have shown increased oil production
using four different types of coal. He is also studying
ways to prevent catalyst deactivation problems, a
common problem in coal liquefaction. As part of his
asphalt research, Guin is researching ways to pre-
vent the absorption of asphalt into porous rock. As-
phalt absorption can cause premature pavement fail-
ure, and he hopes to learn more about the funda-
mental chemistry of absorption in relation to the
properties of asphalt and rock. He hopes to develop a
model for asphalt construction which will help engi-
neers construct better highways.
ARTHUR TARRER's interests lie in coal lique-
faction, asphalt absorption, materials research, en-
vironmental control, and process dynamics and con-
trol. In his process research, he is developing reactor
systems designed for difficult-to-control reactions.
Generally, these are reactions that occur rapidly.
For these reactions, it is virtually impossible to trans-
fer reactive gases to the liquid phase fast enough to
minimize undesirable reactions. Using control tech-


nology such as "bang-bang" technology, which in-
volves switching the reaction rate from high to low
and alternately switching the mass transfer rate
from high to low, Tarrer will be able to control such
reactions. These reactor systems will have applica-
tions to specialty chemical manufacturing, wastewa-
ter treatment, and many other processing areas. As
part of his materials research, Tarrer is also devel-
oping new methodology such as techniques for test-
ing the physical and chemical bonding strengths of
asphalt pavements. He hopes to develop additives
for asphalt that will reduce water-stripping and ex-
cessive absorption of asphalt into the pavement ag-
gregate. In the environmental control area, Tarrer is
working in conjunction with the EPA, the Depart-
ment of Defense, and companies such as Dow Chemi-
cal and Exxon to develop waste minimization tech-
niques to help the environment. He also currently
operates a pilot plant facility that recycles about
100,000 gallons of waste oil by reprocessing it into
reusable products such as specification grade fuel
oil. One way that Tarrer uses his process control ex-
pertise is to interface digital programmable control-
lers to processing unit operations such as those used
in waste oil recycling pilot plants.
GLENNON MAPLES conducts research in
equipment failure detection techniques, equipment
performance, and energy use. He hopes to develop
methods to detect equipment failure and to evaluate
the performance of the equipment, including how
the variables relate to the desired output. His re-
search in energy use allows him to measure the
energy used by various machines and to evaluate
methods of energy optimization.
ROBERT CHAMBERS and Y.Y. Lee are the
principal researchers in the biochemical/biomedical
area, and both also perform pulp and paper research.
Some of Chambers' research involves enzyme engi-
neering-alcohol detoxification in particular. Re-
search is aimed at a fundamental understanding of
the interaction of the multi-enzyme system with the
physiological system of the body and on further de-
velopment of the multi-enzyme system. Chambers is
also investigating the use of semi-permeable micro-
capsules and semi-permeable hollow fibers for use
as novel bio-reactors in the treatment of chlorinated
organic present in the effluent produced in paper
Y.Y. LEE's specialty is biochemical engineer-
ing, but he also conducts research in the areas of
transport mechanisms in cellulosic biomass and

energy conversion. Lee hopes to achieve a high-yield
and efficient conversion of biomass into alcohols by
way of novel bioreactor/separator systems. He is also
developing a process in pulp and paper by applying a
low-water processing concept. Two of the problems
faced by the pulp and paper industry are how to
minimize production losses and how to treat mill
effluent so it will minimally affect the environment.
Lee hopes to reduce the water input in the pulp
digester and to use a sulfur-free pulping reagent to
minimize negative environmental effects. This ap-
proach will greatly reduce polluted effluent and will
result in reduced chemical costs, sulfur-free process-
ing, increased production yields, unbleached pulp
brightness, and adaptability.
C. WILLIAM ROOS' work is in the separation
of high-value fermentation proteins. He hopes to
identify and quantify the factors which limit the rate
and capacity of solid-liquid affinity chromatographic
systems for large-scale application to protein sepa-
ration. He also hopes to develop a concept for sepa-
rating proteins to combine affinity-complex forma-
tion with membrane separation.
MAHMOUD EL-HALWAGI performs research
in process design, process control, and optimization.
In particular, he is researching a unified approach to
the synthesis of general separation networks, syn-
thesis of reactor-separator networks, hazardous
waste minimization through chemical process syn-
thesis, and mathematical modeling and optimiza-
tion of fluidized-bed combustors.
JAY H. LEE conducts research in process con-
trol, control structure selection for large-scale sys-
tems, design and control of chemical processes, and
identification and inferential control via neural net-
works. He concentrates mainly on his process con-
trol research; his goal is to design modern process
control systems that will make significant improve-
ments in the economics, safety, and flexibility of

Because of the continued growth of the pro-
gram at Auburn, plans are underway for a new chemi-
cal engineering building that will house state-of-the-
art laboratories. Our large, well-funded research pro-
gram can support many graduate students and we
welcome applications from qualified students. We
also encourage undergraduate applications to our
program. 7





University of Florida
Gainesville, FL 32611

IN THE EARLY DAYS of our profession, many
departments had a technical course to orient stu-
dents to the industrial world before graduation.
Courses of this nature fell out of favor, however, and
now only a few departments have courses solely in-
tended to ease the transition of seniors into the mar-
ketplace. Some of the material has, of course, been
incorporated into other courses, e.g., design or en-
gineering economics. At the University of Florida, the
senior seminar continues, although a humanistic em-
phasis was introduced in the 1970s by inclusion of top-
ics such as interviewing skills and engineering ethics.
This one-hour course is required for all graduating
seniors and is usually taken at the beginning of the
last year of classes. The goals of the course are: to
prepare the student for interviews and for career de-
cisions; to develop an awareness of ethical choices; to
develop an awareness of professional concerns such as
chemical toxicity and patent law; and to develop skills

Mark Orazem is associate professor of chemical
engineering at the University of Florida, where he
contributes to Microfabritech (a center for study of
electronic materials). He holds BS and MS degrees
from Kansas State University and a PhD from UC
Berkeley. His research interests include electro-
chemical systems, corrosion, and semiconductors.

Dinesh O. Shah received his undergraduate train-
ing at the University of Bombay and his doctoral de-
gree from Columbia University (1965). In 1970 he
joined the chemical engineering faculty at the Uni-
versity of Florida, and is currently serving as chair-
man of that department. He is also the Director of the
Center for Surface Science and Engineering and is
a professor of anesthesiology and biophysics. His
research centers on interfacial phenomena in engi-
neering and biomedical systems.

in presenting technical information in short talks. In
a sense, this is a capstone course for the professional
development of our students in much the same way
that design or unit operations laboratories provide a
capstone for their technical development. To our
knowledge, this type of course is not at all common,
and we believe that similar offerings should be seri-
ously considered by other departments.


The structure of the course closely followed a syl-
labus developed and used by John O'Connell when he
was in this department. The final class schedule for a
group of sixteen seniors is presented in Table 1, and

Schedule: Professional Development Course

Session Topic
1 Organizational meeting and introduction
2 Self analyses-careers Open-ended discussion of possible
criteria to be used in selecting the ideal job. Assignment I due.
Assigned listing of personal top ten criteria for selecting a job.
3 Interview preparation Open-ended discussion of possible
criteria to be used in selecting the ideal job applicant. Assigned
interview partners and companies to be represented. Assign-
ment II due.
4 Interviews (role playing)
5 Interviews (role playing)
6 Interviews (role playing)
7 Graduate School* Guest speaker, graduate school coordinator.
8 Ethics and Values Assignment III due
9 Ethics and Values
10 Chemical toxicity Guest speaker from Division of Environ-
mental Health and Safety
11 Inventions and patents Guest speaker, patent attorney
12 Individualtalks
13 Individual talks
14 Individualtalks
15 Individualtalks
16 Individual tralks Closure

C Copyright ChE Division ASEE 1990


the homework assignments are presented in Table 2.
The objectives of the course follow.

* To prepare the student for interviews and for
career decisions.

A number of homework assignments and class
exercises were selected for this purpose. The initial
assignment required that the students write a five-
page paper on their goals in life and the aspects they
considered to be important. We wanted the students
to think of their careers and their lives after gradua-
tion in terms of their objectives rather than in terms
of fitting into their perceptions of a recruiter's needs.
This was reinforced by a class discussion on criteria
to be used in choosing an "ideal" job. The instructors
served primarily as moderators and recorders of sug-
gestions put forth by the students, and concluded the
exercise by requesting that students give us their top
ten criteria for selecting a job. The results were com-
piled in the same way that NCAA (basketball or foot-
ball) teams are ranked, and this compilation (shown in

Homework Assignments

Assignment I Write a (five-page) autobiographical paper address-
ing questions such as: Who am I? What is important
to me? What would I like to achieve? What have I
learned in college about myself?
Assignment II Learn to use the Career Resource Center:
A. Attend CRC minischool session of yourchoice and
write a one-page outline of its content and useful-
B. Interview role-playing.
Assignment ll Ethical Dilemmas:
A. Listthree differenttechnological innovations of the
last fifty years which are "mixed blessings," and give
at least three "good" and "bad" aspects of each
B. Ethical problem questionnaire.

Assignment IV

Any time before the 16th session, attend a nontech-
nical cultural event (e.g., lecture, concert, demonstra-
tion, art exhibit). Write a one-page paper describing
the activity and what you got out of it.

Individual talk Develop and deliver a ten-minute talk on some tech-
nical topic of general (non-ChE) interest. Submit a
200-word abstract for the talk. Visual aids must be
used. See handouts for more information and for a list
of suggested topics.
Others (At beginning of semester) Write a list of your top
ten criteria for choosing a job or company.
(Toward the end of the semester) Given the compi-
lation of top criteria you (as a class) chose in Septem-
ber, list the top ten criteria you would choose now.
Please indicate how, if at all, the class influenced your
thinking on this.

Table 3) was returned to the students.
On the third day of class, a discussion was initiated
in which the students were asked to consider the
criteria they would use in selecting the best candidate
for a job. We were now asking our students to put
themselves in the position of corporate recruiters; our
goal was to help students consider how to put their
best foot forward. Note that throughout these discus-
sions and, indeed, throughout this class, we avoided
lecturing the students on what their criteria should
be. Rather, we served as moderators and brought up
for consideration topics and ideas that were not
brought up by the students themselves.
We used the second homework assignment (Table
2) to encourage students to become familiar with the
Career Resource Center (CRC) at the University of
Florida. This is the university agency that handles
on-campus job interviews, and our students who were
looking for industrial jobs were already somewhat
familiar with it. The CRC offers one-hour courses on
various aspects of interviewing and professional prep-

Top Twenty-Five Criteria for Choosing a Company
(Selections made at beginning of course)
This list is compiled from the top ten criteria turned in for our second
class assignment. The list was obtained by allocating 10 points to the
firstchoice foreach student, 9 to the second, etc. The numberinparen-
theses is the total for the class (16 students). Students were not given
a list of alternatives; they came up with these criteria independently,
and all the selections that were turned in are included here.
1. Location (113)
2. Salary level (95)
3. Type of job (93)
4. Advancement opportunities (89)
5. Management structure and style (67)
6. Values and ethics of company management and coworkers (50)
7. Benefits (47)
8. Working environment (42)
8. Job security (42)
10. Future growth potential (37)
11. Support and/or opportunity for continuing education (33)
12. Flexibility (32)
13. Mobility within company (28)
14. Male/female ratio (including upper management) (24)
15. Lifestyle (21)
16. Company reputation (15)
17. Safety (14)
18. Size of company (13)
19. Emphasis on research and development (10)
20. Sales and/or production position of company (9)
20. Educational opportunities for children (9)
22. Travel opportunities (6)
23. Employee satisfaction and retention (2)
24. Facilities(1)
24. Feeling that the job is worth doing (1)


aration. Our students were required to take at least
one of these courses (in addition to a general introduc-
tory course) and to write a brief report on its useful-
ness. The topics selected by the students included in-
terviewing skills, the mechanics of computerized-
interview sign-up, cover letters, job correspondence,
government jobs, and resume preparation.
A large portion of class time was devoted to prac-
tice interviews. Each team consisted of two students
who selected a company to represent. We asked that
each group select a different company, and we tried
to get a balanced representation of petrochemical, pe-
troleum, semiconductor, and biochemical or phar-
maceutical firms. The companies are listed in Table 1.
The students could use any resource at their disposal
(e.g., the CRC, personal contacts, and talks by com-
pany representatives at student chapter AIChE meet-
ings) to become informed about the company, and on
the day. of the interview a coin-toss would determine
which student would be the interviewer and which
the interviewee. We requested that the two students
study independently to avoid a "canned presentation."
We allocated ten minutes for each interview (two pairs
per day) after which the class would discuss the
strengths and weaknesses of each participant. The
class was asked to fill out a worksheet on the partici-
pants (Table 4) which was returned to the interview-
ing pair.

Questionnaire for Evaluation of Mock Interviews
Use the following questions to generate discussion of the mock
interviews. After the instructor sees them, these sheets will be given
to the interview team. Please make constructive comments.

Date Company
-1 10 How well was the company represented?
1 10 Poise?
D 10 Knowledgeable about the company?
1 10 Project enthusiasm for the company?
1 10 Did the questions asked help distinguish among candi-
dates? What qualities was the interviewer looking for?
71 10 How well did the student represent him or herself?
1 10 Poise?
1I 10 Knowledgeable about the company?
-1 10 Positive impression as employee?
1 10 Answered questions well?
Name two positive characteristics that came out most
clearly in the interview and two that came out least clearly.

We do plan one modification to the mock inter-
views. Contrary to our initial expectations, we now
believe that five minutes per interview is sufficient.
By the third day of interviews, the exercise became
quite tedious for the spectators. In spite of this, the
students (particularly those who had not interviewed
before) placed great value on the experience. Some
even requested a second go at it! We feel that a short-
er time limit would not interfere with the amount the
students learn since, inevitably, the richest interac-
tion took place very early in the mock interview. This
change will allow more time for constructive criticism
and may allow us to schedule three groups per day
instead of two.
A discussion of graduate education rounded out the
portion of this class dedicated to career selection.
While this class is required for all seniors, about
twenty-five percent of our seniors choose to continue
their education, and this course provided a more bal-
anced picture of the opportunities available to them.
* To develop an awareness of ethical choices.
Our main source in this exercise was a series of
articles published in Chemical Engineering [1-4] ask-
ing its readership to respond to a variety of real-life
ethical dilemmas. We asked the students to fill out
this questionnaire and then used it for two days of
occasionally vehement discussions. The AIChE code
of ethics was also presented, but the students were
more interested in the complex problems posed by the
articles. In total, the students were asked to respond
on paper to eighteen different dilemmas, and the top-
ics discussed in class were selected by the students
from this list. The class discussion was augmented by
examples of ethical dilemmas that the teacher had
faced, and the class was encouraged to provide alter-
native solutions to the ones he had chosen.
It may be worth noting that the most hotly de-
bated topic in this section was the question of who
owns the knowledge of an employee. The scenario was
an engineer leaving the employ of a plastics company
to join a fudge-making company. Even though he had
signed a secrecy agreement with the previous firm,
he decides that a proprietary modification to a mixer
used for plastics could be employed equally well for
fudge. The question is whether divulging this new
mixer design to the new company is or is not ethical.
The class was evenly divided on this issue. Students
on the "pro side" argued that an employee's obligation
to suggest any improvements (i.e., to contribute all
his knowledge) to his current employer overrides his
responsibility to his previous employer. They ac-
knowledged that his action was illegal, but (correctly)


S. the most hotly debated topic was the question of who owns the knowledge of an employee ... an
engineer leaves the employ of a plastics company to join a fudge-making company. Even though he had
signed a secrecy agreement with the previous firm, he decides that a proprietary modification to a mixer
used for plastics could be employed equally well for fudge. The question is whether divulging this new
mixer design to the new company is or is not ethical.

pointed out that the object of the exercise was to dis-
cuss ethics, not law. Students on the "con side" held
that an employee has a legal and an ethical obligation
to a former employer not to divulge proprietary infor-
mation. When the problem was changed so that the
modification was the invention of the employee, three-
quarters of the class believed that employing the in-
vention at the new place of employment was ethical.
The students who felt that even under these cir-
cumstances, passing the knowledge on to the new em-
ployer was not ethical (as well as being illegal),
suggested that the employee who invented the mixer
could certainly make improvements to the design and
thus ethically pass this improvement on to his new
We spent quite a bit of time on delineating which
part of our knowledge is generic and which part can
be considered proprietary. Since one of the instructors
(MEO) had recently come to the University of Florida
after filing a patent disclosure at his previous institu-
tion, we were able to discuss how the rights of both
the individual faculty member and the previous uni-
versity were protected. A discussion of the legal as-
pects of the ownership of knowledge was led in a sepa-
rate class by a lawyer from the patent division of the
University of Florida.
This was a very effective and very important part
of the class. We feel it is crucial to expose students to
the types of ethical or moral decisions that they may
face as professional engineers. Many of the problems
have more to do with management than with technol-
ogy, and the personal choice of a pathway through a
dilemma can be supported by development of a keen
sense of professionalism. In other words, ethical en-
gineers see themselves as individuals with respon-
sibilities to themselves, to their society, and to their
profession-not as drones or cogs in a machine. Some
of the comments made by our students (listed in the
section "Student Comments") indicate that, through
this course, they have developed a greater sense of
An emphasis in this area has been made even more
important by the recent development of the field of
ethics and value studies in science and engineering
which is being carried out in departments of
philosophy and/or social sciences (see, e.g., reference
5). This development is, in part, a response to the
vacuum caused by the reluctance of technical people


Topics Chosen by Students for Individual Talks
What is a Semiconductor and How is it Used?
Earthquake Prediction
Technology Involved with the Sail Design of the Stars and Stripes
Gene-Splicing Using Recombinant DNA
The Greenhouse Effect
Supernovas and Life
The Difference Between Stocks and Bonds
Solar Energy
The Role of Government in Scientific Research and Education
Plastics Pollution
How Foreign Nationals Can Stay in the United States
Black Holes
The Mechanism of Vision
Radon Gas: What It Is and What Can Be Done About It
Bhopal: Role of Government/Industry in the Aftermath of a Disaster

to get involved in matters of public policy. We believe
that it is important that leadership in this area be
provided by engineers and scientists who can be
knowledgeable in both the technical and the manage-
rial aspects of the problem. The treatment of ethical
questions in this course represents a small contribu-
tion to this essential area.
The major change we recommend in the way this
material was handled is the reduction of the number
of problems covered in order to allow for more depth.
The students could be asked to consider about nine
dilemmas, and to examine perhaps four in depth. We
plan to include an additional assignment requiring the
students to write a workable code of ethics for en-
* To develop an awareness of professional concerns.
The two topics covered under this heading were
chemical toxicity and patent law. Guest speakers from
within the university were found for both topics. As
mentioned above, a portion of the attorney's talk was
devoted to the legal ramifications of the problem
posed on ownership of knowledge.
To develop skills in presenting technical informa-
tion in a short talk.
The final portion of the class was devoted to ten-
minute presentations by the students. The topics were
to be of a technical nature, but not directly related to
chemical engineering. A list of the topics chosen is

presented in Table 5. Students were required to pro-
vide a one-page abstract at least a day in advance, and
the instructor went over the abstract with the stu-
dent. This was meant to be a constructive and very
interactive enterprise, and no formal grade was given.
The first presentation, given by the instructor,
was entitled "Tips for Technical Presentations." It cov-
ered the basic elements of successful presentations
and concluded with the following:

Give your message three times in three different ways.

Know your audience and be prepared to modify your pres-

Use visual aids to help your audience follow (not to help
you remember) your presentation. Two minutes per slide
provides a reasonable guide for the number of slides
needed for a talk.

Write your abstract to help attract listeners.

This is your audience, and they are here to listen to you.
Enjoy it!

Do not abuse the last item!

Presentations were critiqued by the audience, and
a copy of all comments was given to each speaker.


Perhaps the results of the final exercise provide
the best indication of the value of this course. On the
last day of class, students were given the compilation
of criteria given in Table 3 and were asked to mark,
at this point, their preferences. The results are given
as Table 6. We noticed a number of interesting results:

Location was the dominant criteria in September. The de-
sire to stay near family or in Florida was a prominent
reason. But in December, the type of job became overwhelm-
ingly more important than salary or location. This could
be attributed to other experiences (such as plant visits) as
well as to the influence of the course.

Ethics of the company made it into the top ten in both Sep-
tember and December. We were pleasantly surprised by the
importance the students placed on this even before our dis-
cussion of ethics in engineering.

The importance of job security fell from September to De-
cember. Students simply do not see job security as a major

Importance of the male/female ratio fell from 14 (with 24
points) to 23 (with only one point). This was an overriding
concern of several of our female students in September, but
by December, they did not include male/female ratio as a
criterion at all. Some had received very significant job offers

by December, and perhaps this il,tfuercrd their thinking.

Item number 24 in Table 3 (feeling that the job is worth
doing) was the tenth choice of only one student in September
(who, perhaps, was struggling to come up with ten solid
criteria). The rise in popularity to number 7 in December
is due, in part, to the inclusion of this criterion for consid-
eration by all students.

A number of students commented that, in their
view, some of the categories overlapped. Modification
of Table 6 to incorporate this overlap made only minor
changes in the top five.:
1. Type of Job + Feeling that the Job is Worth Doing (184)
2. Working Environment + Values and Ethics of Company
Management and Coworkers (128)
3. Salary Level + Benefits (110)
4. Location (106)
5. Advancement Opportunities + Mobility within Com-
pany (93)

A similar grouping of the results in September

1. Salary Level + Benefits (142);
2. Advancement Opportunities + Mobility within Com-
pany (117);
3. Location (113);

Top Twenty-Five Criteria for Choosing a Company
(Selections made at end of course)

1. Type of job (135) {previous ranking was 3 with 93 points, or 3:93]
2. Location (106) [1:113]
3. Salary level (87) [2:95]
4. Working environment (73) [8:42]
5. Advancement opportunities (72) [5:89]
6. Values/ethics of company management/coworkers (55) [6:50]
7. Feeling that the job is worth doing (49) [24:1]
8. Safety (39) [17:14]
9. Management structure and style (38) [5:67]
10. Job security (27) [8:42]
11. Support and/or opportunity for continuing education (26) [11:33]
11. Flexibility (26) [12:32]
13. Benefits (23) [7:47]
14. Emphasis on research and development (21) [19:10]
14. Mobility within company (21) [13:28]
16. Travel opportunities (18) [22:6]
17. Lifestyle (17) [15:21]
18. Employee satisfaction and retention (15) [23:2]
19. Size of company (13) [18:13]
20. Future growth potential (11) [10:37]
21. Company reputation (10) [16:15]
22. Facilities (3) [24:1]
23. Male/female ratio (including upper management) (1) [14:24]
24. Sales and/or production position of company (0) [20:9]
24. Educational opportunities for children (0) [20:9]


S. .a one-hour course devoted to the
professional development of our students
is a worthwhile enterprise .. A course of this
nature provides a capstone for the professional
development of our students .

4. Type of Job + Feeling that the Job is Worth Doing (94);
5. Working Environment + Values and Ethics of Company
Management and Coworkers (92).

The most significant change here is the increased
importance of the categories corresponding to the
type of work the students envision doing and the at-
mosphere in which they will be working.


It is difficult to assign grades in a largely non-tech-
nical course. In previous years, the grades were as-
signed on the basis of class attendance and homework
assignments by a strict numerical formula (i.e., sub-
tract 1/2 letter grade for each unexcused absence).
We found that class attendance was very good, and
all students participated in the assignments. As a re-
sult, we assigned 'A's to all students. We, of course,
do not guarantee this for future classes.


Students were asked to comment on how this class
influenced their decisions on the criteria they would
use to select a job. Most used this as an opportunity
to comment on the class as a whole. Some of their
responses are

Before I took this class I didn't think too much about
these points to choose a job. Now, I'm looking at inter-
viewing with a lot of companies, and I do look for these

This class has certainly influenced my thinking. It has
developed in me a more professional attitude in choos-
ing a job. Yes, I still think that location and salary level
should be the most determining criteria since they are so
necessary in ensuring a happy life to a human and con-
sequently affecting his ability to be efficient. But topics
like hazards in industries opened my eyes to the impor-
tance of safety in a company, how serious it should be
and how dangerous the consequences of lack of it could
be for a company and the workers. One thing that really
struck me is the criteria about ethics and values. Before
this class, I always thought of an engineer as an individ-
ual that should apply his intellectual skills in the work
field without any deep involvement. At the end of this
class, I know that I have to develop my sense of jude-
ment when it comes to people, and my ability to make
good decisions that will allow me to be honest to my-
self, to my career and to the company where I will be

I think this course has enabled me to see that I shouldn't
have a preconceived notion of "the perfect job" before I
go hunting. Although I only redefined a few things in my
ratings, I've become a little more open-minded when I
look at a potential job opportunity.

I think that this course has influenced my criteria for
choosing a company. It increased my consideration of a
company's values and ethics as well as consideration of
general categories other than salary, type of job, and lo-

*The ethics exercise influenced me quite a bit it is a topic
not often stressed.

This course motivated me to think about the relation of
my future profession with my life style.

The most helpful topic was the interview preparation. I
have never had an opportunity to have an actual inter-
view and after having the in-class (practice) interviews
and listening to the criticism, I tried to correct the prob-
lems which were pointed out....I believe that I will see
the benefit of this course, even more, in my personal
and professional life.


We believe that a one-hour course devoted to the
professional development of our students is a worth-
while enterprise, and, as such, should be considered
by other departments. A course of this nature pro-
vides a capstone for the professional development of
our students that complements the usual capstone
courses for their technical development. We have
suggested some minor changes to the syllabus which
we plan to implement in the next session.


The success of this course is due in large part to
the tradition begun by John Biery and to the outline
developed by John O'Connell, who is now at the Uni-
versity of Virginia. We wish to thank the guest speak-
ers: Tim Anderson, Dan Endicott, and Susan Wray.


1. Kohn, Philip M., and Roy V. Hughson, "Perplexing Problems
in Engineering Ethics," Chem. Eng., p. 97, May 5 (1980)
2. Hughson, RoyV., and Philip M. Kohn, "Ethics," Chem. Eng.,
p. 132, September 22 (1980)
3. Matley, Jay, and Richard Greene, "Ethics of Health, Safety,
and Environment: What's 'Right'?" Chem Eng., p. 40, March
4. Matley, Jay, Richard Greene, and Celeste McCauley, "Health,
Safety, and Environment: CE Readers Say What's'Right',"
Chem. Eng., p 108, September 28 (1987)
5. Frankel, Mark S., editor, Science, Engineering, and Ethics:
State of the Art and Future Directions, Report on an AAAS
Workshop and Symposium, February 1988, Amer. Ass'n. for
the Advancement of Science, Washington, DC (1988) 1


Random Thoughts...


3. Michelle, Rob, and Art

North Carolina State University
Raleigh, NC 27695-7905

The scene is the AIChE student chapter lounge
at a large southeastern university. Three juniors-
Michelle, Rob, and Art-are studying for the second
quiz in the introductory transport course. Art got the
high grade in the class on the first quiz, Michelle
was close behind him, and Rob got 15 points below
class average. They've been at it for over an hour.

Michelle: "What about this stuff on non-Newtonian
flow-I don't think I really get it."

Art: "I think we can forget it-I've got copies of Snavely's
tests for the last five years and he's never asked about

M: "Maybe, but it's the real want to analyze
blood flow, for instance, Newtonian won't work."

A: "So what...the only blood flow we're going to have to
worry about is ours on this test if we don't stick to the
stuff Snavely is going to ask."

M: "Yeah, but if we don't..."

Rob: "Hey Art, is there going to be any of that Navier-
Stokes trash on the quiz?"

A: "Yeah, there usually is, but no derivations-you just
have to know how to simplify the equation."

R: "Rats-I hate that garbage."

M: "I've been looking through Bird, Stewart, and
Lightfoot...there are all sorts of Navier-Stokes problems
in there. We could try to set some of them up."
R: "Nah, too much grind-I just need to do enough to
get my C, my degree, and my MG. Art my man, why
don't you haul out those old tests and let's just memo-
rize the solutions."

A: "Okay, but that may not...hey, look at this
question-he's used it for three years in a row. Parts (a)
and (b) are just plug-and-chug, but he throws a real
curve ball here in Part (c)-I don't know how to do it."

R: "How much is Part (c) worth?"

M: "Never mind that-let me see it.. Okay, he's asking
about velocity profile development-you just need to use
the correlation for entrance length."

A: "What are you talking about? I never heard of that

M: "He never talked about it in class but it's in the read-
ing. You need to calculate the Reynolds number and
then substitute it in this dimensionless correlation, and
that gives you..."

R: "I'm gonna grab a Coke from the machine, guys-
when you get it all straight, just tell me what formula I
plug into, okay?"

A: "Yeah, sure. So it's just this correlation, huh Mich-
elle-do I need to dig into where it comes from?"

M: "Probably not for the test, but I was trying to think
why you would want to know the entrance length, and
it seems to me that if you're designing a piping system
that has a lot of short pipe segments it would be impor-
tant to know how well your pressure drop formulas will
work...blood flow again, in capillaries, or maybe lubri-
cating oil in a car engine, or..."

A: "Forget it-that stuffs not going to be on this test.
Even Snavely wouldn't be that tricky. Now look at this
problem here..."

These three students illustrate what Entwistle
[1] calls orientations to studying. Michelle has a
meaning orientation, Rob a reproducing orientation,
and Art an achieving orientation. The characteris-
tics of the orientations are as follows:

Copyright ChE Division ASEE 1990


Meaning Orientation Michelle tends to
take a deep approach to learning, meaning that
she tries not just to learn facts but to understand
what they mean, how they are related, and what
they have to do with her experience. Meaning-
oriented learners are characterized by an
intrinsic motivation to learn ("I want to learn
this material because it interests me and Ifind
it relevant to my life ") and a tendency to question
conclusions offered in lectures and readings.

Reproducing Orientation Rob almost
always takes a surface approach to learning-
following routine solution procedures but not
trying to understand where they come from,
memorizing facts but not trying to fit them into
a coherent body of knowledge. Reproducing
learners are characterized by an extrinsic
motivation to learn ("I've got to learn this to pass
the course, to graduate, to get a good job") and
an unquestioning acceptance of everything in
the book and in lectures. They often do poorly
in school.

Achieving Orientation Art's primary goal
is to get the highest grade in the class, whatever
it takes. Achieving learners take a strategic
approach to learning, which involves finding out
what the instructor wants and delivering
it-digging deep when they have to, staying
superficial when they can get away with it.

Sooner or later most faculty bull sessions lapse
into complaints that most of our students are Robs
and pitifully few are Michelles. Unfortunately, few
of us do anything in class to stimulate our students
to take a deep approach: we just give them tricky
tests to see if they can "do more than plug in," and
then gripe that they're apathetic and incompetent
when they can't. Fortunately, there's something we
can do besides complain. The following conditions in
a class have been shown to increase the likelihood
that students will adopt a deep approach to learning

Student-perceived relevance of the subject matter.
Students will not struggle to achieve a deep
understanding of material that seems pointless
to them, any more than we would. To motivate
them to do it, let them know up front what the
material has to do with their everyday lives (e.g..
fluid flow in their cars and circulatory systems,
heat and mass transfer and reaction in the
atmosphere and their homes and respiratory and
digestive systems) and with significant problems
they will eventually be called on to solve (e.g..

fabricating improved semiconductors.
developing alternative energy sources, avoiding
future Bhopals).

Clearly stated instructional objectives, practice, and
feedback. Students are not born knowing how
to analyze deeply, and little in their precollege
experience is likely to have fostered that ability.
To get them to pull meaning out of lecture
material and to solve problems that go beyond
those in the text, spell out these objectives and
give concrete examples of the kind of reasoning
desired. Then explicitly ask the students to carry
out deep analysis in class and on homework and
give them constructive feedback on their

Appropriate tests. Provided the preceding
conditions have been met, include questions that
call for deep analysis on all tests. If the students
know they will only get surface questions (closed-
ended exercises that require only standard
solution procedures) they will likely take a
surface approach to learning the material. If they
expect some deep questions (more open-ended
questions that require greater understanding),
all of the Michelles, most of the Arts, and
perhaps some of the Robs will see a need to take
a deep approach and do so.

Reasonable workload. If students have to spend
all their time and energy just keeping up, they
will fall back on a surface approach.

Choice over learning tasks. Provide bon us problems
and/or optional projects, and/or alternatives to
quizzes, and/or optional self-paced study, and/
or choices between group and individual efforts.

The research indicates that by establishing
these conditions we may substantially increase the
number of our students who think critically about
the material we are presenting, try to discover its
meaning and its relationship with other material they
have previously learned, and routinely question the
inferences and conclusions that we present in class.
Whether or not we'll know what to do with these
people once we have them is a question for another


1. Entwistle, N., "Motivational Factors in Students' Ap-
proaches to Learning," in R.R. Schmeck, Ed., Learning
Strategies and Learning Styles, Plenum Press, New York,
Chap. 2 (1988)
2. Ramsden, P., "Context and Strategy: Situational Influences
on Learning," in R.R. Schmeck, Ed., op. cit., Chap. 7 1





University of Bath
Bath BA2 7AY, England

ciation of the concept of a heat transfer coefficient
even though they are familiar with the concept of ther-
mal conductivity. An example of heat loss from single
and double glazed windows (which is developed later
in this paper) helps to bridge this divide; a beneficial
link with familiar surroundings is established.

Students should already be familiar with the
method for calculating heat flow along a lagged bar,
as shown in Figure 1. This involves a straightforward
application of the following equation (which is often
called Fourier's law)
q=-kA ( (1)

It is also necessary that the concept of interfacial
temperature be understood. This may be introduced
via the composite slab problem, which is both interest-
ing and relevant. In this problem it is supposed that
there are two slabs of equal area A, of thickness tj
and t2, and with thermal conductivity ki and k2, re-
spectively. Let the temperatures be defined by Figure
2. Now the flow of heat through each slab is the same;

Robert Field obtained his BA and PhD degrees from
the University of Cambridge. He is a lecturer in the
School of Chemical Engineering at the University of
Bath and is author of the book Chemical Engineer-
ing: Introductory Aspects (Macmillan Education).
Research interests center on heat, mass, and mo-
mentum transfer.
C Copyright ChE Division ASEE 1990

klA(6hot-Oi) k2A( O-Oo)ld)
q (2)
ti t2
The interfacial temperature will rarely be known, but
there are two equations, and q and 0i are generally
the unknowns. Rearrangement gives
shot --i = q-t (3)
0i 0old = q (4)

Addition of Eqs. (3) and (4) gives

hot- ld=q- + k- (5)
(kA kA)




Distance x

FIGURE 1. Flow of heat along a lagged bar of uniform
thermal conductivity


that is

q hot- old (ehot cold)A
(t, tz t, + t
Sk,A k2A) k, k)

This is similar to Ohm's law: q is the flow of heat
instead of current; Ohot-0cold is equivalent to the driv-
ing force, the potential difference; and the t/kA terms
are thermal resistances. The equation can be
generalized to give the heat flow through a composite
of many layers

q= (ehot- cold)A (7)
ti t2 t, .
Ck, k2 k3 )

where Ohot-Ocold are the temperatures of the outer
surfaces of the composite.

An Oversimplification

A familiar example is the loss of heat through
closed windows. Students can be encouraged to esti-
mate the loss using the above theory. For illustrative
purposes, single and double glazed windows of the fol-
lowing specifications will be assumed: single glazed 4
mm thick glass with k = 1.05 Wm-'K-'; double glazed




Distance x

FIGURE 2. Flow of heat along a composite bar (and def-
inition of temperatures used in text)

A familiar example is the loss of heat through
closed windows. Students can be encouraged
to estimate the loss .for illustrative
purposes, single and double glazed
windows will be assumed .

units incorporating two panes of 4 mm thick glass and
a 12 mm air gap whose thermal conductivity is taken
to be 0.023 Wm-'K-1. The area of glazing will be taken
as 3m2, the room temperature as 200C, and the air
temperature as -4C.
It could be argued that for the calculations the
temperatures should be in Kelvin, not degrees Cel-
sius. However, the numerical results are not affected
since temperature differences are the same in K and
C. This is an opportunity for pointing out that normal
engineering practice does not slavishly follow the SI
set of units and C will be retained. Application of Eq.
(7) leads to the following estimates:

heat loss through [20-(-4)]3
double glazing = 0 =136 W
double glazing =[0.004 0.012 0.0041
__ ~ + I-
1.05 0.023 1.05

heat loss through [20-(-4)]3
single glazing 0.004 18,900 W

The last figure is clearly excessive since 18.9kW is
greater than the heat input for a whole house! If the
inside surface of the pane were 200C and the outer
surface -4C, then the heat loss would undoubtedly be
in excess of 18kW. It is interesting to ask students if
the temperature gradients shown in Figure 3 are

Inside air
at 200C

Outside air at

FIGURE 3. Temperature profile across a pane of glass in
the absence of boundary layers


At this juncture, an opportunity arises to point out
that one must be explicit about one's assumptions. Fig-
ure 3 implies that the outside air which is close to, and
right up to, the window is all at -4C, despite a large
outflow of heat. Similarly, there is no temperature
gradient on the room side. The model which was im-
plicitly assumed, and which has been made explicit in
Figure 3, is unrealistic. The model illustrated in Fi-
gure 4 can be introduced as being much more realistic,
but still not exact. An engineer learns the importance
of using intelligent approximations and of making the
best possible estimate from incomplete information.
In a small way this is illustrated by the current prob-
Having intuitively noted that there are regions
close to both glass-air boundaries over which the tem-
perature changes from bulk air temperature to glass
temperature, it is useful to introduce a physical pic-
ture so that calculations can be performed. It may be
agreed that a reasonable approximation is to assume
that the air, both on the inside and the outside, can
be represented by a near stagnant film or boundary
layer across which there is an appreciable tempera-
ture change and a well mixed bulk which is isothermal.
It is reasonable to assume that the film thicknesses
would be 2mm for the room side and 1.5mm for the
outside, if the wind speed is low. A reduction to 1mm
is appropriate if the wind speed is higher. Their recal-
culations should give the following results:

heat loss through [20- (-4)]3
single glazing =-= 462W
(low wind speed) +0. + 0. 0.0015)J
0.023 1.05 0.023

heat loss through [20- (-4)3
single glazing = = 536 W
(high wind speed) .0 + 0. +
0.023 1.05 0.023)

The thicknesses and the resulting heat loss values
are reasonable, and the model (which is one of pure
conduction through a stagnant layer) might be of in-
terest and, in some circumstances, of use. However
the teacher will undoubtedly wish to point out that
the aim is to have a value for the thermal resistance,
and it does not matter if the heat loss mechanism is a
combination of convection and conduction, provided
an accurate estimate can be made. In the above exam-
ple, the inside thermal resistance, t/(kA), is 0.002/
(0.23 x 3) = 0.029 K W-1. Taking the reciprocal (kA/t)
and converting it into per area form (k/t), one has the
heat transfer coefficient. In this case it equals 0.023/
0.002 11.5 Wm-K '. This example has not only in-
troduced the concept of a heat transfer coefficient but


FIGURE 4. Temperature profile across a pane of glass in
the presence of boundary layers

also illustrates that a balance between theory and em-
piricism has been productive. The insights into the
physics underpinning heat transfer coefficients lead
to a better theoretical understanding. The coefficients
that are subsequently developed are not tied to any
particular model. They can be treated as purely em-
pirical constants of proportionality, the knowledge of
which permits (given knowledge of surface area and
temperature difference) the calculation of the amount
of heat transferred.
While one can always find a film thickness to give
a reasonable result, one can rarely predict the appro-
priate film thicknesses for a new situation. However,
knowledge of the film thicknesses is now seen to be
insignificant. In contrast, the important film heat
transfer coefficients can readily be calculated from
predictive equations. These enable an engineer to give
an a priori prediction of performance under changed
circumstances. The confidence attached to this predic-
tion is enhanced if the predictive equation has some
theoretical underpinning.

The above example can be used to introduce the
concept of overall heat transfer coefficients. The
method for combining these coefficients is similar to
the method for combining thermal resistances, and an
analogue for Eq. (7) will be obtained. The tempera-
tures for the current example are defined in Figure 4.
Remembering that the heat flow through the glass
and the two boundary layer films is the same, the
students should obtain

k A(09 0g.)
q = homA(0mom gi)= kAgi = houA(Ogo ou)
tg (8)


where hroom is the heat transfer coefficient for the
inside (or roomside) boundary layer, and hotr is the
heat transfer coefficient for the outside boundary
Rearrangement and addition as before gives

(9oo -9out)=[ t, 1
(room-A roomm k out
(0 room out )A (9)
1- + t9 +*"
room kg ho

The outside heat transfer coefficient will be depen-
dent on wind speed and window position, which need
to be determined, but the exact mode of heat trans-
port (e.g., the balance between convection and conduc-
tion) is unimportant and of scientific, not engineering,
interest. The rate of flow of heat per unit area per
unit temperature difference is
A(Oom- o0)

This is, of course, the overall heat transfer coefficient,
U, and from the above equation its relationship to the
individual coefficients is seen to be of a reciprocal na-

-__ + + (10)
U room kg hout

It may be pointed out that this is analogous to the
summing of electrical resistances; the term on the left-
hand side is the overall resistance to heat transfer and
those on the right are the individual resistances.

It may be noted that the assumption of a stagnant
layer of air between the panes of the double glazed
units was also an oversimplification. The circulation
currents within the enclosed space reduce the insulat-
ing effect. In order to reduce this loss of insulating
power, certain manufacturers fill the space with inert
gases which are several times denser than air. Frame
construction also influences heat loss, and the final
overall heat transfer coefficients range from 2.0 to 3.5
Wm-K-1 for double glazed units. This compares favor-
ably with the 7 Wm-K-1 of typical single glazed win-
dows, but the difference is not as dramatic as students
and others first suppose.
The pedagogic value of the example is not limited
to the introduction of the overall heat transfer equa-
tion. There is the opportunity to develop (a) students'

understanding of natural convection by considering in
greater detail the physical process occurring in the
enclosed cavity between the panes, and (b) their ap-
preciation of forced convection by considering the ef-
fect of wind speed upon the outside film heat transfer

The author is grateful to Macmillan Education for
permission to reproduce figures and items of material
from the book, Chemical Engineering: Introductory
Aspects, which was published in 1988 (ISBN 0-333-


A area
h film heat transfer coefficient
k thermal conductivity
q heat flux
t thickness
U overall heat transfer coefficient
x distance
0 temperature


1,2 refers to slabs as shown in Figure 2
cold,hot,i refers to cold-side, hot-side, and interfacial
positions as shown in Figure 2
g glass
gi glass-room interface
go glass-outside interface
out outside
room room-side J

Book reviews
by L.H. Sperling
John Wiley & Sons, One Wiley Dr., Somerset, NJ
08873; $39.50 (1986)

Reviewed by
F. Rodriguez
Cornell University

This textbook is written at the level of the senior
or beginning graduate student who has had no previ-
ous courses in polymers. It is presumed that a course
in organic polymer chemistry will follow.
Recognition of the importance of polymers for
chemists and chemical engineers has yet to be ac-
knowledged in many departments. However, the
Continued on page 172.


Award Lecture


The ASEE Chemical Engi-
neering Division Lecturer for 1989
is J. L. Duda of Pennsylvania State
University. The 3MCompanypro-
vides financial support for this
ann ual lectureship award, and its
purpose is to recognize outstand-
ing achievement in an important
field of ChE theory or practice.
A native ofDonora, Pennsylva-
nia a small steel mill town nearPittsburgh) Larry earned
his BS in chemical engineering in 1958 from Case Insti-
tute of Technology and his PhD in chemical engineering
from the University of Delaware in 1963. After gradu-
ation he joined the Process Fundamentals Laboratory at
Dow Chemical Company in Midland, Michigan, as a
research engineer. Eight years later he joined the chemi-
cal engineering department at The Pennsylvania State
University as an associate professor and subsequently
became head of the department in 1983.
He has conducted research in a wide range of fields
including polymer processing, enhanced oil recovery,
arctic engineering, molecular diffusion, rheology, nu-
merical analysis of coupled transport processes, and
tribology. Although these activities appear to be unre-
lated, most of his research involves the application of
transport phenomena principles to problems involving
polymers and macromolecules. He has conducted re-
search with fifteen different members of Penn State's
faculty in chemical engineering and related fields, and
this work has resulted in over one hundred research
Professor Duda has taught a wide range of classes in
chemical engineering, in cluding specialty courses in the
polymer field and advanced transport phenomena. In
addition to teaching undergraduate and graduate stu-
dents, he has been the advisor or co-advisor of 35 MS and
15 PhD graduate students.
In 1980 Professor Duda received the Penn State
Engineering Society's Award for Outstanding Research
Achievement, and in 1981 he and a colleague (James
Vrentas) were the joint recipients of the William H.
Walker Award of the AIChE. He also was the recipient of
a NSF Visiting Scholargrant to National Taiwan Univer-
sity in 1978.

Pennsylvania State University
University Park, PA 16802

W HEN I WAS NOTIFIED that I was the recipient of
the 1989 3M Lectureship Award, I was very
pleased and surprised. After the initial euphoria, how-
ever, I panicked when I realized I also had to give a
lecture at the ASEE National Meeting. I looked up the
past lectures published in Chemical Engineering Edu-
cation. This was a mistake! Not only did the list of au-
thors read like "Who's Who in Chemical Engineering,"
but the lectures also covered a wide range of subjects.
However, they could be put into two broad classifica-
tions: many were reviews of the research fields of the
lecturers, while others dealt with a philosophy of educa-
tion and teaching. Like most researchers, I enjoy talk-
ing about my research field, but most of my audience
would probably be bored since the subject is outside the
area of expertise of a general engineering audience. On
the other hand, I am sure that the average engineering
educator would also be bored by an hour of my
philosophy on education. Consequently, I decided to
combine these two general subjects in my lecture.
University professors are in the knowledge busi-
ness. First, through our teaching, we transfer knowl-
edge to our students; second, we produce knowledge for
the world through our research; and third, we transfer
a knowledge of how to produce more knowledge. That
is, we teach undergraduate and graduate students how
to conduct research. Of these three activities, I feel the
third has the greatest potential for payback, yet it is the
one that we essentially neglect when we discuss our
profession and when we seek ways to improve our effec-
The philosophical component of my lecture involves
teaching students how to conduct research. To present
this philosophy, I have decided to incorporate it as part
of a discussion of one of my research projects. Through-
out the discussion, I will utilize quotes from many other
individuals which mirror my own philosophical point of

0 Copyright ChE Division ASEE 1990


My main premise is that students often initiate their first research project with a distorted view of the
research process. Students are aware of the scientific method and usually feel that research
closely follows that method. However, I feel that research more closely
resembles a random walk than an idealized scientific method.

view. I hope to present more than just information con-
cerning my subject matter. I agree with J. Epstein's
observation that
What great teachers teach is not just subject matter but
an attitude toward it, an approach to it.
My main premise is that students often initiate their
first research project with a distorted view of the re-
search process. Students are aware of the scientific
method and usually feel that research closely follows
that method. However, I feel that research more closely
resembles a random walk than an idealized scientific
method. Students usually do not realize this when they
initiate a research project, and unfortunately we
educators do not attempt to dispel their illusions.
In the title to this lecture, a "random walk" refers
to the reality of many research projects, and "porous
media" refers to the specific topic I will be discussing-a
study of the flow of polymer solutions in porous media.
Many individuals contributed to the scientific content of
this lecture and the most prominent were my graduate
students S. K. Fan, S. A. Hong, and H. L. Wang, and
my colleague, E. E. Klaus. More details of the technical
aspects of this paper are available [1-4]. However, I
have no one to blame except myself for the philosophical
components of this lecture.
I feel that most educators fail to prepare students
for their first encounter with research. Perhaps we are
embarrassed by the fact that our research programs do
not progress in a systematic manner paralleling scien-
tific methods as perceived by the general public. There
is no question that the body of scientific knowledge is
very well-systematized. However, the production of
new scientific knowledge is clearly related to artistic
creativity. While we use the scientific approach to test
results, when we start a project, all kinds of hurdles and
false leads present themselves, and the overall process
often resembles a random walk towards our well-de-
fined objective. Nobel Prize winner Szent-Gyorgyi
stated it succinctly:
Research means going out into the unknown with the
hope of finding something new to bring home. If you
know in advance what you are going to do, or even to
find there, then it is not research at all.
Similarly, W. P. Schmitt stated:
Most studies prove that almost all truly significant in-
ventions come outside the formal planning process.

Unfortunately, many bureaucrats who control re-
search funding do not understand these facts. While we
cannot do much about them, we can do a better job of
preparing the researchers of the future to take on the
challenge of creative research.
There is a dichotomy which new researchers have
difficulty in reconciling. Although the actual process of
doing research usually does not follow the idealized sci-
entific method, we always report our results as if it did.
We feel a need to report our results in the most succinct
and logical manner; including all the false starts, failed
experiments, and theories would only confuse and de-
tract from the new knowledge that we want to add to
the scientific and engineering base. When writing up
the first research project, a young researcher should be
made aware of the advice of O'Conner and Woodford:
Remember, a thesis or any scientific paper should not
be the history of an inquiry, but its outcome.
In this paper, however, I am going to ignore that
good advice and present the account of a project involv-
ing the flow of polymer solutions in porous media. By
chronicling the actual history of this project, I hope to
make new researchers more aware of the actual re-
search process.
The main objective of this program was to develop
an ability to predict the pressure drop vs. flow relation-
ship for the flow of polymer solutions in porous media
by independently characterizing the porous media and
the rheology of the fluid. In essence, we wanted to de-
velop an analog of Darcy's Law for polymer solutions.
In Darcy's Law for Newtonian fluids, the porous media
is characterized by the permeability, and the Newtonian
fluid is characterized by the viscosity. In the flow of
Newtonian fluids, the porous media is usually modeled
by some sort of capillary model, and the most commonly
followed approach is the one represented by the Blake-
Kozeny equation as presented in Table 1. Because of
the success of this approach for Newtonian fluids, it was
natural that the analogous approach be considered for
non-Newtonian solutions of polymers. One of the first
attempts along this line was the work of Christopher
and Middleman [5], presented in Table 2, in which the
power law was used as a model for the fluid.
When my group at Penn State initiated this work,
we developed an experimental technique in which we
could actually measure the flow rate as a function of
pressure drop for the flow of non-Newtonian solutions


in porous media. We initiated experiments with a well-
characterized porous media and beds of uniform spheri-
cal glass beads. Review of the literature indicated that
the main problems associated with the study of flow in
packed beds were a result of the complications due to
end effects. First of all, excess pressure drops occurred
at the entrance and exit of packed beds, and the increase
in porosity near the walls containing the bed caused
channeling. Both of these problems were addressed in
the experimental technique shown in Figure 1. By sub-
tracting the total pressure drop across the 3-inch packed
column from the pressure drop across the 6-inch packed
column, the pressure dropped through 3 inches of fully

Model for Flow of Newtonian Fluid in Porous Media

Modelof PorousMedia Modelof Fluid

Capillary Model Newtonian Fluid
(Mean Hydraulic Radius)
Porous Media Characteristics = -y

E, Dp, Tortuosity (25/12)

Blake-Kozeny Equation

Ap DpE3
L 1501t(l1-)2

K= '-
150(1 -2)

Model for Flow of Power-Law Fluid in Porous Media

Mode of Porous Medi

Capillary Model

E, Dp, Tortuosity (25/12)

Model of Fluid

Power Law Fluid

= Ky n

Christopher-Middleman Equation

ne 6Ap /
3n+1 25KL)

S- I+l/n


developed flow in the center of the 6-inch column could
be determined. Similarly, a layer of glass beads was
incorporated into an epoxy coating on the walls of the
column to eliminate radial variations in porosity. This
experimental technique resulted in excellent pressure
drop vs. flow rate measurements for Newtonian fluids
as presented in Figure 2. The straight diagonal line in
the figure represents predictions of the flow behavior
based on the capillary model for the porous media. The
slight deviation of the data from the prediction at high
Reynolds numbers is probably due to inertial effects
which are not included in the capillary model.
Most young researchers would be quite pleased with
results such as those presented in Figure 2 and would
be ready to wrap up the project. However, two quotes
are apropos at this point:

If an experiment does not hold out the possibility of
causing one to revise one's views, it is hard to see why
it should be done at all.
Peter B. Medawar
To limit oneself to what one can be rigorous about is


6" Packe


FIGURE 1. Experimental Apparatus Used to Study Flow in
a Packed Column of Glass Beads.


often to limit oneself to trivial questions.
M. C. Bateson

Too often young researchers design experiments to
test well-documented theories, and it is not clear what
they would conclude if their experimental results did
not agree with the theory. For example, if the experi-
mental results presented in Figure 2 did not agree with
the capillary model theory, would they conclude that
the capillary model approach for describing the flow of
Newtonian fluids in porous media is incorrect? Since
that model has been evaluated by numerous inves-
tigators, I doubt that they would be willing to make
such a bold statement. Instead, disagreement between
the experiment and theory would probably cause them
to reconsider and to modify the experiment until agree-
ment was attained. In this case, the results of Figure 2
were used to show the validity of the experimental
technique, and then the technique was used to study
the flow of polymer solutions in the beds of glass
spheres. Some very interesting results were attained
for polymer solutions which appear to behave as purely
viscous solutions and others which show elastic effects.
These results are available in the literature and are not
reproduced here since they would distract from the
main theme of this paper.
At this point, the research group at Penn State was
very pleased with the program and was prepared to

I I I I f
107 10-6 105 104 10"3 10-2 10 I
Reynolds Number, NRE
FIGURE 2. Friction Factor-Reynolds Number Relationship
for Flow of Newtonian Fluids in Packed Column.

There is a dichotomy which
new researchers have difficulty in
reconciling. Although the actual process of
doing research usually does not follow the
idealized scientific method, we always
report our results as if it did.

spend more time elucidating the flow of polymer solu-
tions in the well-characterized beds of glass spheres.
However, it turns out that most young researchers are
not cognizant of the fact that in the shadow of every
research project there lurks a sponsor. In this case, the
Department of Energy was sponsoring the research
(which was related to enhanced oil recovery) and the
project had an industrial advisory group. This industrial
advisory committee pointed out that they did not feel
the study of the flow of polymer solutions through pris-
tine packed beds of uniform glass spheres shed much
light on the practical problems which involved the flow
of complex mixtures of polymers, oil, electrolytes, etc.,
in porous rock containing clay and minerals in addition
to wide variations in porosity and other characteristics.
It became very clear that in order to maintain our fund-
ing we would, at the minimum, have to study flow in
The unwanted interference of a sponsor is a reality
that every researcher has to face, and the sooner a
young researcher becomes aware of this the better. The
key is to appreciate the interesting scientific and en-
gineering challenges encountered along the way. In fact,
in the work being reviewed here, it could be argued
that the net result of unwanted sponsor interference
was a greater contribution to our scientific knowledge
Consultations with our petroleum engineering col-
leagues who routinely study flow in sandstone under
conditions simulating oil recovery conditions indicated
that extensive new equipment would be required. The
velocities in oil reservoirs are an order of magnitude of
a foot a day, requiring sophisticated pumps and expen-
sive apparati to measure the very low associated pres-
sure drops. Naturally, the required funds were not
available in our contract! Another truism that young
researchers must quickly assimilate is that sponsors al-
ways want more than they are willing to pay for!
The project faced the dilemma which is charac-
teristic of many research programs across the coun-
try: the equipment and instrumentation were not suf-
ficient to meet the challenge of the research. Although
I would be the last to disagree with the point of view
that the instrumentation and experimental infrastruc-


It is like "keeping up with the Joneses"! I feel we must warn our young researchers
not to let a profusion of instruments, apparati, computers, etc., constrain their creativity or the
direction of their research. The main constraint for scientific progress has been, and will continue to be,
the limitations of the ingenuity and creativity of the researchers.

ture of America's colleges and universities are in crit-
ical need of an infusion of resources, I do feel that
there is a tendency for hardware to take too promi-
nent a position in our scientific endeavors. Sometimes
it seems that everyone has to have a SEM, FTIR,
HPLC, and a supercomputer, etc., before they can
make any progress. It is like "keeping up with the
Joneses"! I feel we must warn our young researchers
not to let a profusion of instruments, apparati, com-
puters, etc., constrain their creativity or the direction
of their research. The main constraint for scientific
progress has been, and will continue to be, the limita-
tions of the ingenuity and creativity of the research-
In the project I am dissecting, the lack of funds for
the "essential" equipment resulted in a breakthrough.
To meet the challenge of studying flow in porous sand-
stone under conditions simulating oil reservoirs, my
colleague, E. E. Klaus, developed a simple, inexpen-
sive technique illustrated in Figure 3. Basically, this
apparatus is analogous to an Ostwald capillary vis-
cometer where the capillary has been replaced by a
piece of porous media. The flow rate is measured by
the time the fluid requires to fill a calibrated efflux
bulb. The low pressure drop required to simulate re-



FIGURE 3. Porous Media Viscometer.

servoir conditions is easily attained by utilizing the
head of the fluid in the reservoir above the efflux
bulbs. This apparatus could be easily calibrated with
Newtonian fluids to produce results which are in ex-
cellent agreement with theory. However, once these
experiments were initiated with polymer solutions,
several complications arose. It became apparent that
large quantities of solution had to flow through the
porous sandstone before steady state conditions were
realized, and the permeability of the sandstone was
irreversibly changed by exposure to the polymer solu-
tion. To eliminate the cost of the preparation of sand-
stone samples during the preliminary experiments
and to enhance the probability of reproducible results,
well-characterized filter paper was utilized as porous
media. The permeability of the porous media was de-
termined with a Newtonian saline solution, and then
the media was exposed to a flowing polymer solution
until steady state conditions were attained. Finally,
the polymer solution was replaced with the original
saline solution and the reduction in the permeability
of the porous media was determined. Although the
new experimental technique seemed to be accurate
and reproducible, the preliminary results with filter


S 0 200 250


0 50 100 150 200 250

FIGURE 4. Relationship Between Initial Permeability and
Residual Permeability for Flow of 500 ppm Xanthan Gum
Solution Through Filter Paper.


60o I I -

01 ----I I
0 200 400 600 800 900
FIGURE 5. Relationship Between Initial permeability and
Residual Permeability for Flow of 500 ppm Xanthan Gum
Solution Through Three Different Porous Media.

01 1 I I 1
0 100 200 300 400 500
FIGURE 6. Influence of the Hydrodynamic Size of Polymer
Molecules in Solutions on Residual Permability of Bradford
Sandstone. o 500 ppm Xanthan Gum and 200 ppm NaCI;
o 500 ppm Xanthan Gum and 2% NaCI; A Ultrasonic
Degraded Solution of 1000 ppm Xanthan Gum and 200




paper as presented in Figure 4 did not seem to be
correct. Although the students conducting the exper-
iments swore by the accuracy and reproducibility of
the results, I concluded that the data in Figure 4 were
ridiculous. Everyone agreed that the polymer mole-
cules were irreversibly absorbing on the walls of the
porous media channels and that this caused a reduc-
tion in the permeability. However, these results ap-
peared to indicate that thicker polymer coatings were
associated with larger pores. The natural extension of
this data would indicate that if we conducted experi-
ments on a sewer pipe, we would plug off the pipe! As
D. J. Boorstin said,
The greatest obstacle to scientific discovery is not ig-
norance but the illusion of knowledge.

Will Rogers stated the same point of view more suc-

It ain't what you don't know that hurts you-it's
known' what ain't so.

Progress on this project was held up for months
because of our preconceived notions of what was oc-
curring in the porous media. Because of the limited
range of the filter paper, data could not be extended
beyond the range covered in Figure 4. Finally, we
decided to take the bull by the horns, and we con-
ducted experiments in actual sandstone. As the re-
sults in Figure 5 clearly show, the initial trend, which
seemed to go against logic, was reversed at higher
initial permeabilities, and the behavior followed the
anticipated trend after a maximum was attained.
Although everyone associated with the project was
finally convinced that these results were real, they
did not represent a contribution until a mechanism
consistent with this behavior was envisioned. I think
Einstein said it best:
Knowledge cannot spring from experience alone, but
only from the comparison of the inventions of the in-
tellect with the observed facts.

Like most new knowledge, the explanation for be-
havior shown in Figures 5 and 6 appeared trivial once
it was stated. The polymer molecules could not enter
the pores which were smaller than the hydrodynamic
volume of the polymer chains in solution. Since the
polymer did not enter the small pores, these pores did
not become coated with a layer of adsorbed polymer
molecules. The selective flow of polymer molecules
was analogous to the phenomena which was the basis
of exclusion chromatography. If this mechanism was
correct, then the maximum occurring in Figure 5
should have shifted towards smaller initial per-


", i -- - ,

meabilities if the hydrodynamic volume of the polymer
molecules was reduced. Since the xanthan gum used
in this study was not synthesized at different molecu-
lar weights, the size of the chains of this polymer in
solution were modified by two techniques. By subject-
ing the polymer solutions to severe mechanical agita-
tion, the covalent bonds of the polymer chain were
broken. A lower molecular weight polymer resulted
from this mechanical degradation. The effective hy-
drodynamic size of the polymer molecules in solution
was also reduced by increasing the electrolyte concen-
tration of the solutions. The confirmation of xanthan
gum chains in solution was enlarged by repulsion
forces between ionized groups on the molecules. An
increase in electrolyte concentration formed a double
layer around these charge groups and reduced the re-
pulsion and the effective size of the polymers in solu-
tion. The data presented in Figure 6 qualitatively con-
firmed this mechanistic point of view. The curve with
the maximum was that obtained for the flow of the
unaltered xanthan gum polymer molecules in Berea
sandstone. The upper curve shows the results when
the size of the polymer chains were reduced by
mechanical degradation, and the third curve shows
that the behavior associated with the flow of xanthan
gum molecules had been contracted into smaller hy-
drodynamic volumes by a significant increase in the
electrolyte concentration. It is interesting to note that
this behavior had not been observed previously, and
probably would not have been observed if this research
program had the experimental equipment which was
generally believed necessary to study flow in sand-
stone under reservoir conditions.
At this stage in the project, we decided that a com-
prehensive understanding of flow in porous media
could not be realized when the complications due to
the complex rheology of the solution were coupled to
the complications associated with polymer-wall in-
teraction. Consequently, the next set of experiments
was conducted in porous media of high permeability
where polymer chain-pore wall interactions were not
significant. The original plan was to study the flow of
polymer solutions under conditions where they be-
haved as purely viscous fluids, and then to move on
to the more interesting area of viscoelastic solution.
We anticipated that we would quickly confirm the
applicability of capillary models to describe the flow
of purely viscous, non-Newtonian fluids in porous
media. The utility of capillary models for such systems
had been confirmed by numerous investigators, in-
cluding our own earlier studies with packed beds of
glass beads. However, these elegant plans were
quickly scuttled by new experimental data, and the

random-walk nature of the project continued. As T.
H. Huxley stated,
The great tragedy of science-the slaying of a beauti-
ful hypothesis by an ugly fact.
It is interesting that playwright Eugene O'Neill
perhaps best describes a pitfall which is most dangerous
for the older researcher:
A man's work is in danger of deteriorating when he
thinks he has found the one best formula for doing it. If
he feels that, he is likely to feel that all he needs is
merely to go on repeating himself

All our elegant plans and preconceptions were wiped
out by the new data produced with the porous media
viscometer depicted in Figure 3. Instead of following
the advice and the procedure which his advisors had
suggested, a new student on the project started to pres-
ent the data in raw form (as shown in Figure 7) rather
than presenting dimensionless friction factor as a func-
tion of Reynolds number. As Figure 7 indicates, when
the pressure drop (as represented by the head of the
fluid between the reservoir and efflux bulb) was plotted
as a function of velocity through the porous media, the
experimental measurements did not agree with the
model based on the capillary model and a power law
At first, this was not disturbing since the model pre-
diction could be modified by changing adjustable
parameters such as tortuosity. However, there were no

0.0001 0.001 0.01 0.1 1.0

FIGURE 7. Velocity as a Function of Pressure Head in a
Porous Media Viscometer for Flow of a 3000 ppm Xanthan
Gum Solution Through Sandstone With a Permeability of
7.0 Darcy. Predicted Line Based on Power Law Model.


adjustments in the power law model to change the slope
of the prediction lines when presented in the form of
Figure 7. In other words, the line representing the pre-
diction of the model could be raised or lowered by ad-
justing some parameters in the model, but the conven-
tional model could never be adjusted to give a slope
which agreed with the experimental data. At first, we
assumed that this problem was due to the inadequacy
of the power law model in describing the rheology of the
fluid. It is a well-known fact that all polymer solutions
exhibit Newtonian behavior at low shear rates and then
a transition to shear thinning and power law behavior
is observed at higher shear rates. Consequently, to re-
concile the difference between the experimental data
and the theory based on the capillary model, an Ellis
model was used to describe the rheology of the polymer
solutions, and the capillary model approach was coupled
with this theological equation to develop a new model.
A comparison of this new model with the experimental
data is presented in Figure 8. These data are represen-
tative of data obtained from many different polymer
solutions. In this log-log plot, the model based on the
Ellis model rheology is a curve which comes closer to
fitting the experimental data but still does not represent
an adequate description of the flow of purely viscous
polymer solutions in porous media.
After much effort, we concluded that the limitations
of the overall model were not due to the limitations of
the theological model describing the viscosity-shear be-

0.001 0.002

0.005 0,01 0.02


FIGURE 8. Velocity as Function of Pressure Head in a Por-
ous Media Viscometer for Flow of a 5000 ppm Carboxy
Methylcellulose Solution Through Sandstone With a Per-
mobility of 7.0 Darcy. Predicted Line Based on Ellis Model.

havior of the solutions, but were somehow inherent in
the basic capillary model. This study showed that the
excess pressure drops associated with the converging
and diverging flow regions of any porous media must be
included in a model of flow of non-Newtonian fluids in
porous media. The assumption of fully developed flow,
which is characteristic of all capillary models, eliminated
the utilization of these models for accurately describing
non-Newtonian flow in porous media. Fortuitously,
capillary models can describe the flow of Newtonian
fluids in porous media since the pressure drops as-
sociated with fully developed flow and the excess pres-
sure drops in the entrance and exit regions are linearly
related. Consequently, a constant tortuosity factor can
incorporate the effects of the excess pressure drops and
the tortuosity of the flow path. However, a constant
tortuosity factor is inadequate for the description of the
flow of purely viscous polymer solutions or viscoelastic
solutions in porous media. Finally, we concluded that
two criteria were required to describe the flow of a
purely viscous polymer solution in porous media.

1. The model of the porous media must include the converging
and diverging nature of the porous media.
2. The theological model of the fluid must include the transition
from Newtonian behavior at low flow rates to shear thinning
behavior at higher shear rates.

From these studies, we concluded that to describe
the flow of polymer solutions in porous media, the model
of the porous media must include converging and di-
verging sections. However, to describe the flow, the
complete equations of motion for the non-Newtonian
fluid would have to be solved for this two-dimensional
flow field. If such a problem were offered to a new group
of chemical engineering graduate students, it would be
a very popular project indeed since it involves extensive
utilization of the computer to solve a non-linear set of
partial differential equations. Today we see more and
more research which is based on complex numerical
analysis of well-established partial differential equations
such as the Navier-Stokes equations. Computers have
had a very significant impact on science and engineer-
ing, and this impact will probably increase in the future.
As tools, modern computers are a wonderful contribu-
tion to research. However, I feel there are problems
associated with the utilization of computers (particularly
by students) which are sometimes overlooked in the
present environment of computer euphoria. A few
quotes clearly present this point of view:
The more computer power we have, the less students


know what they're doing.

Computers can raise a barrier to intuition.

Alvin White

E. Block

Several years ago, James Wei published a humorous
paper in Chemtech concerning the number of paramet-
ers it would take to fit an elephant. A cliche among
researchers is that the number of parameters in some
correlations would fit an elephant. So Professor Wei
went on to determine the number of parameters needed
to fit the shape of an elephant. An interesting experi-
ment is to assign the following problem to a group of
students: Determine the minimum number of paramet-
ers required to produce a shape which can be recognized

FIGURE 9. Conventional Least Square Fit of an Elephant.

FIGURE 10. A Different Point of View!

as an elephant. Students love such a challenge since it
enables them to use all the power of the computer, and
it gives a sense of great accomplishment without the
stress of really thinking about a problem. The students
are ingenious in their ability to come up with new spline
fitting techniques, the use of parallel processes, etc.
However, they will inevitably come up with a result
similar to that shown in Figure 9, and the number of
parameters for all of the students will be approximately
the same. Computers are touted as a great contribution
to our theoretical ability. However, J. Willard Gibbs
The purpose of a theory is to find that viewpoint from
which experimental observations appear to fit the pat-

In other words, the purpose of theory is to find a
different point of view. Computers can provide a more
detailed vision, but they very seldom change a point of
view. To make a breakthrough in the problem stated
above, the student must think about an elephant, do a
coordinate rotation, and find a line of symmetry. The
resulting different point of view is presented in Figure
10. Either the front or the back of an elephant has a line
of symmetry and the number of parameters needed to
represent those points of view are significantly less than
the usual point of view (Figure 9).
In conclusion, I feel that computers are very useful
tools, but that we must train our students to recognize
the danger of allowing computers to set the pace and
direction of their work. They need to take time for re-
flection on their problems. Only then can they enjoy the
benefits of the computer without falling into its empiri-
cal clutches.
I would like to express my appreciation to the 3M
Company, to members of the Selection Committee, and
to all those who were involved with my nomination for
the opportunity to present my point of view. My collec-
tion of quotes is not well documented, and I apologize
if I misquoted anyone or if I failed to give appropriate
credit for material I used in this presentation.

1. Duda, J.L., E.E. Klaus, and S.K. Fan, Soc. ofPet. Engrs. J.,
2. Wang, F.H.L., J.L. Duda, and E.E. Klaus, Society of Petro-
leum Engineers, paper 8418 (1979)
3. Hong, S.A., J.L. Duda, and E.E. Klaus, Polymer Preprints,
4. Duda, J.L., S.A. Hong, and E.E. Klaus, Ind. Eng. Chem.
Funds., 22, 299 (1983)
5. Christopher, R.H., and S. Middleman, Ind. Eng. Chem.
Funds., 4, 422 (1965)
6. Wei, J., Chemtech, 128, (Feb. 1975) 1



The following detachable pages describe
some industrial employment opportunities for
graduating chemical engineers. Please post the
information in a conspicuous place for the benefit
of your students, or distribute the pages to students
who may be interested.
These companies have expressed a definite
interest in hiring chemical engineers in the areas
described, and we strongly encourage students
seeking employment to respond as indicated.

Ray W. Fahien
Chemical Engineering Education

College Relations Department, M-260E
P.O. Box 1926
Spartanburg, SC 29304

Milliken is a major manufacturer of textile products for apparel, commercial,
home and industrial markets. Milliken Chemicals operates two modern
Specialty Chemicals plants in South Carolina. The company was founded in
1865 and now has 50 plants and 14,000 associates in the US (15,000 worldwide).
The Milliken environment is characterized by challenge, accomplishments,
innovation, advanced technology, promotion from within based on individual
performance, and extensive education and training opportunities. The chemical
engineering jobs are in South Carolina and Georgia.

CITIZENSHIP REQUIREMENTS: U.S. citizenship or Permanent Resident Visa


HOW TO APPLY IF UNABLE TO SCHEDULE CAMPUS INTERVIEW: Send cover letter with functional area
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above address.



Process Engineering: Provides technical support in textile dyeing and finishing
operations and in Specialty Chemicals production.
Responsibilities include manufacturing compliance with
customer product quality specifications and process
efficiency/improvement project assignments.

Manufacturing Management: Responsible for the production resources of people and
machinery. The first line production manager may be
promoted to either Advanced Production Manager or
Process Engineer in the dual career ladder.

Research: Develops new products and associated machinery or
processes. Prefer PhD, but will consider MS.

An Equal Opportunity Employer

Ad Publishd in Chemical Epineerin Education. Vol. 24, No 3 (1990)

University Relations
Box 1713-CH
Midland, MI 48674

Dow manufactures and markets chemicals, plastics, metals, consumer products,
pharmaceuticals, specialty products and services, and agricultural products. Dow
USA will hire over 200 chemical engineers in 1990 and has over 2600 chemical
engineers working in all functions and geographic locations.

CITIZENSHIP REQUIREMENTS: Only U.S. citizens, aliens who have a legal right to work and
remain permanently in the U.S. or aliens who qualify as "Intending Citizens" under the
Immigration Reform and Control Act of 1986 are eligible for employment.


address, stating your job interests and geographic preferences.


Functional Area


Process Engineering


Research and Development


Degree Level







Fields of Special Interest

Math Modeling

Polymer Processing

Polymer Characterization


Major Hiring Locations

Michigan, Texas, Louisiana, Ohio, California

Michigan, Texas. Louisiana, Ohio, California

Michigan, Texas, Louisiana, Ohio, California

Michigan, Texas, Louisiana, Ohio, California

Offices in over thirty major cities

Tech Center Locations

Michigan, Texas, California

Michigan. Texas, California, Ohio

Michigan, Texas, California, Louisiana

Michigan, Texas

An Equal Opportunity Employer

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P.O. Box 52332
Houston, TX 77052

Distinguished for its worldwide integrated operations, Texaco is a leader in all phases of
the petroleum industry which include exploration, producing, manufacturing,
transportation, marketing, and research. Active in some 140 countries and territories,
Texaco ranks as one of the largest industrial companies and employs 25,000 people in
the United States.

CITIZENSHIP REQUIREMENTS: U.S. citizen or authorized to work full time in the U.S.

Oklahoma, California, Washington State, New York, Delaware, and Kansas.
Thomas E. Gougenheim, Manager College Recruiting
Texaco, Inc.
P.O. Box 52332
Houston, Tx 77052


Functnl Area Degree Level Maior Hiring Locations

Process Engineering

Project Engineering


Fields of Special Interest





Texas, Louisiana, California, Washington,
California, Texas, Louisiana

New York, Texas, California

Tech Center Locations

PhD Beacon, NY; Pt. Arthur, TX; Austin, TX;
Montebello, CA

An Equal Opportunity Employer

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Chemical Engineering Employment Coordinator
Section M4556
39 Old Ridgebury Road
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Our parent, Union Carbide Corporation, is a Fortune 50 Company, recognized globally
for leadership in its three business groups: Chemicals & Plastics; Industrial Gases; and
Carbon Products. Founded in 1917, Carbide employs 46,000 worldwide, with 25,000 in the
USA. Annual sales for Chemicals & Plastics approached $6 billion in 1989. Key UCC&P
products include polyethylene, latex and specialty polymeric resins; ethylene
oxide/glycol and derivatives; urethane catalysts and additives; silicones; alcohols and
organic solvents.

CITIZENSHIP REQUIREMENTS: U.S. citizenship or Permanent Resident Visa (for BS/MS)
southeast, southwest, and Rocky Mountain
transcripts) to above address. Be sure to include a cover letter specifying your
functional and location preference. (See below)


Functioal Area Degree level Maor Hiring Locations
Design (Process; Control Systems) BS,MS Charleston, WV
Environmental/Safety Engineering MS Charleston, WV
Manufacturing (Production; Env. Protection) BS,MS Bound Brook, NJ; New Orleans, LA;
and Houston and Victoria, TX;
Process/Project Engineering Charleston and Parkersburg, WV
Purchasing and Distribution BS Charleston, WV
R&D (Polymer Applications/Tech Service; MS Bound Brook, NJ; Charleston, WV; Tarrytown, NY
Process Development)
Technical Sales BS Metropolitan areas, nationwide

Felds of Special Interest Tech Center Locations
Catalysis, Polymers, Separations Bound Brook, NJ; Charleston, WV

UCC&P has been recognized for its innovative technologies by receiving several prestigious
Kirkpatrick Awards (sponsored by Chemical Engineering Magazine). Two of these, UNIPOL
(polyolefins) and Low Pressure Oxo (alcohols), are licensed internationally and produce
in excess of 15 billion lbs/yr of plastics and solvents.
An Equal Opportunity Employer

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Shell began operations in the United States in 1912. Emphasizing innovative
technology and sound engineering, it has grown to be a major company employing
in excess of 30,000 people throughout the United States. Chemical engineers are
utilized in the recovery of oil and natural gas, refining and chemical plant
operations, and sales activities.

CITIZENSHIP REQUIREMENTS: Candidates must be legally authorized to work in the United
States. Will not consider candidates with student visas.
Primary work locations include the Gulf Coast, California, Illinois, and Washington

Manager Recruitment
Shell Oil Company
Department D2
P.O. Box 2463
Houston, TX 77252



Process Engineering: Provide technical support to petrochemical operating units,
plan and develop new facilities plus major and minor revisions to existing facilities.
Computer Process Control: Provide technical support to petrochemical process
control systems, including systems modification/enhancement.
Production Engineering: Optimization of oil/gas wells and reservoir performance,
design and application of enhanced recovery programs, thermal recovery
processes, planning and economic evaluation of operations and multiple flow
analysis and application.
Chemical Sales: Provide market intelligence and customer service in support of sales
efforts. Perform market research and development and market chemical and
polymer products.

An Equal Opportunity Employer

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120 Long Ridge Road
Stamford, CT 06904


Olin Corporation is a diversified company with core business in chemicals,
metals, and ammunition. A Fortune 200 company headquartered in
Stamford, Connecticut, Olin employs 17,000 people worldwide and has
annual sales exceeding $2 billion.

U.S citizenship or permanent resident visa is required for employment

Nationwide-undergraduate and PhD
Resume and cover letter to
Ms. Leah Lethbridge
Regional Supervisor, College Relations
Olin Corporation
120 Long Ridge Road
Stamford, CT 06904


* Sales

* Business Evaluation


Development, Process,
Maintenance, Production,

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Lake Charles, LA; Charles-
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TN; Lake Charles, LA; Joliet,
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P.O. Box 2000
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Merck & Co. is a worldwide, research intensive health products company that
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application which clearly states educational background, objective, and work
experience to: Theresa Marinelli, Manager College Relations
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Functional Area DereeLevel MaIor Hirina Locations

Corporate Division
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Employee Relations Department
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Established in 1802, Du Pont today is a diversified international company,
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Professional Staffing Section
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>- BS/MS

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Deree Level Major Hiring Locations

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Write to: Professional Recruiting Staff, P.O. Box 7318, San Francisco, CA 94120-7318
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Advertisement published in Chemical Engineering Education Volume 24, No 3 (1990)

class and home problems

The object of this column is to enhance our readers'collection of interesting and novel problems in chemical
engineering. Problems of the type that can be used to motivate the student by presenting a particular principle
in class, or in a new light, or that can be assigned as a novel home problem, are requested as well as those that
are more traditional in nature, which elucidate difficult concepts. Please submit them to Professor James 0.
Wilkes and Professor T. C. Papanastasiou, ChE Department, University of Michigan, Ann Arbor, MI 48109.
11 -.1)___________________________



Georgia Institute of Technology
Atlanta, GA 30332-0100

Applied mathematics problems in chemical
engineering, useful to educators, often appear in
various trade journals. Many of these applications
have been in the area of fluid dynamics, specifically
concerning the time requirements to drain process
vessels, which come in a variety of geometrical
shapes. Thus, formulas have been summarized [1] to
compute the times required to empty vessels of four
different shapes: vertical cylinder, cone, horizontal
cylinder, and sphere. Later articles gave similar for-
mulas for draining elliptical vessel heads [2] and
elliptical saturator troughs [3]. An approximate
method for estimating fluid level changes in vertical
cylindrical tanks with a multiplicity of outlets (or
leaks), of various sizes and at different elevations,
has also been presented [4].

All of the above results are based upon the
assumption of orifice-type drains, e.g., short tubes,
and ignore any associated piping. One article [5]
derived a formula for computing the time to drain a
vertical cylindrical tank, considering drain piping.
Later works [6,7] gave analogous formulas for drain-
ing spherical tanks and elliptical dished heads, re-
spectively, with drain piping. Another (not uncom-

Jude T. Sommerfeld is a professor in the
School of Chemical Engineering at Georgia
Tech. He received his BChE from the Univer-
sity of Detroit and his MSE and PhD degrees,
also in chemical engineering, from the Univer-
sity of Michigan. His 25 years of industrial
and academic experience have been primarily
in the area of computer-aided design, and he
has published over 100 articles in this and"
other areas.
Cpyright ChE Dutision ASEE 1990

mon) shape of process vessel in the chemical indus-
try is conical. Computation of the time required to
empty such a vessel through associated drain piping
is also amenable to analytical solution, as shown
below. A sketch of this configuration is given in
Figure 1.


From the Bernoulli equation, applied to points
1 and 2
PL V2 P, g V.,2
P, gc + 1 + Z, = g + V + Z- + he (1)
p g 2g p g 2g -
With the conventional assumptions that P, = P2 and
V, = 0, we have
Z, = V-+Z2 +h, (2)
Introducing the Moody friction factor (f) for the drain
fL V (3)
h, = (3)
d 2g
and noting that Z1 Z2 = H, Eq. (2) can be solved for
the drain pipe velocity:

V, 2gH (4)

A dynamic material balance for the liquid in
the tank yields
A =- aV, (5)
The cross-sectional area of the liquid level in the
tank at any time is merely the circular area de-
scribed by the radius r at the current level h, or nr.

CId di+f ij


FIGURE 1. Sketch of a conical tank with associated drain

From similar triangles we have
r R
= =-a(= TAN ) (6)
h Y

A= rta2h2 (7)

Recognizing that a = ed2 / 4 and after inserting Eqs.
(4) and (7) into Eq. (5), we have

2 h2 dh -d2 2gH
dt 4 fL
Lastly, since

h=H-ho (
the differential equation to be integrated becomes

(Hh)2 dH (d 2 2 1 (10)

Integrating Eq. (10) from an initial (t = 0) liquid
level elevation of Ho to some final level, Hp then
yields the following expression for the time required


Two special cases are of interest. The first of
these corresponds to complete draining of a partially
filled conical tank. In this case, H = ho, and Eq. (11)

t=C(2H 4hH3 +2h H i -h 5/2 (13)

The second special case is concerned with complete
draining of a completely filled cone. In this case, Ho =
Y + ho, Hf = h and there results

t= 2C(3Y2-4Yh+8h) y2+ho -8hS/2] (14)
15 0 0~"O' ~lV '"


A conical tank with a height of 3m and a top
diameter of 1.2m is initially filled with water to a
level of 2.4m. How long will it take to drain this
liquid through a drain pipe system with 150m of
equivalent length and with an inside pipe diameter
of 1.5cm? The Moody friction factor for this piping
system is equal to 0.0185, and the elevation of the
outlet from this drain system is one meter below the
bottom of the conical tank.

From the problem data

Ho = 3.4m, Hf = ho = 1.0m,

a=0.2, C=2190s/m5/2

Inserting these values into either Eq. (11) or Eq.
9) (13), we find a drainage time requirement of t =
6108s, or 1.70hr.

By way of comparison, from the earlier work
[1] the time required to drain the same amount of
liquid out of an identical conical tank through a
short pipe with the same diameter of 1.5cm, assum-
ing an orifice discharge coefficient equal to 0.80, is

4hoHo 2h -(2H
3 +2h ) H- 5
3 0j

4hoHf +2h2 Hf


(11) A = cross-sectional area of the liquid level in the tank
at any time



( 2H2
t= [ H5 o

a = cross-sectional area of the drain piping

C= L d ) 2g d )
(2a 1 ( fL

D = upper diameter of the conical tank
d = inside diameter of the drain piping
f = Moody friction factor
g = acceleration due to gravity
g = conversion factor
H = liquid height above the drain pipe outlet at any
h = liquid level in the tank at any time
ht = head loss in the piping
h = elevation of the tank bottom above the drain pipe
L = equivalent length of the piping
P = pressure
q = liquid flow rate out of the tank
R = upper radius of the conical tank
r = radius of the liquid level at any time
t = time
V = liquid velocity
Y = height of the conical tank
Z = vertical elevation

Greek Letters
a = R/Y
0 = angle formed by the cone with the vertical axis
n = number pi (3.14159...)
p = liquid density
f = final condition
o = initial condition
1 = liquid surface in the tank at any time
2 = drain pipe outlet


1. Foster, T.C., "Time Required to Empty a Vessel," Chem. Eng.,
2. Koehler, F.H., "Draining Elliptical Vessel Heads," Chem. Eng.,
91,10,90 (1984)
3. Sommerfeld, J.T., "Compute Inventory in Saturator Troughs,"
Textile World, submitted for publication
4. Elder, H.H., and J.T. Sommerfeld, "Rapid Estimation of Tank
Leakage Rates," Chem. Processing (London), 20, 4, 15 (1974)
5. Loiacano, N.J., "Time to Drain a Tank With Piping," Chem.
Eng., 94,13,164 (1987)
6. Schwarzhoff, J.A., and J.T. Sommerfeld, "How Fast Do Spheres
Drain?" Chem. Eng., 95, 9,158 (1988)
7. Shoaei, M., and J.T. Sommerfeld, "Draining Tanks: How Long
Does It Really Take?" Chem. Eng., 96,1,154 (1989) 0

book review

by Charles A. Wentz
McGraw-Hill Book Company, 1221 Avenue of the
Americas, New York 10020; $46.95 (1989)

Reviewed by
Ralph H. Kummler
Wayne State University

The nation's need for educated and trained
professionals in hazardous materials and waste
management is enormous and growing [1,2]. In a
recent survey paper, my colleagues and I concluded
that universities were beginning to respond to the
need, albeit slowly [3]. We were able to identify 113
universities offering credit courses related to hazard-
ous waste management (HWM), and 52 universities
providing non-credit short courses at the professional
level, for a total of 130 universities providing some
kind of HWM education. This new area of knowledge
is being studied by a very wide array of practitioners,

from traditional chemical and civil engineers and
chemists to environmental scientists, environmental
health professionals, and medical technologists. It
appears that a whole new graduate profession is
emerging, since there is plenty ofconventional chemi-
cal and civil engineering to be accomplished, but the
additional role ofinterdisciplinary management must
be implemented. There is a clear need for such new
managers at (almost) the entry level, and the career
path leads up to the vice-presidential level when
environment, health, and safety aspects are com-

In this context, the pioneering text, Hazardous
Waste Management, by Charles A. Wentz, fills an
enormous need as the first teaching textbook on the
market. I expect this book to enable virtually all
chemical, civil, and applied science departments to
introduce a survey course in HWM. The author is
particularly well-qualified to have undertaken this
task, having a rare blend of industrial, university
Continued on page162.





University of Michigan
Ann Arbor, MI 48109-2136

HE HOMEWORK AND examination problems that
students encounter in a traditional chemical en-
gineering class typically have unique correct solu-
tions. Such problems certainly provide necessary
practice in applying the fundamental course concepts,
but if they are used exclusively students might be-
lieve, improperly, that all engineering problems are
similarly structured. Worse yet, an exclusive diet of
well-defined, single-right-answer problems might
leave students unprepared for the more open-ended
problems they will face in industry or in graduate re-
search. While it is true that students are generally
exposed to a measure of open-ended problem solving
in the capstone design course, such exposure is com-
paratively brief and it occurs late in the curriculum.
Recognizing the importance of open-ended prob-
lems in engineering and their under-representation in
the traditional engineering curriculum, the chemical
engineering department at the University of Michigan
set a departmental goal of increasing our under-
graduates' ability to solve open-ended problems. To
achieve this goal we assign at least one open-ended
problem in each of our required undergraduate class-
es. The structure of the open-ended problems is such
that they are major, semester-long projects in which
students work together in groups of three to five. The
open-ended problems offer natural opportunities for

Phillip Savage is an assistant professor of chemical
engineering at the University of Michigan. He received
his BS from Penn State and his MChE and PhD
degrees from the University of Delaware. His research
interests are in reaction pathways, kinetics, andmecha-
nisms. His current projects include studies of reactions
in supercritical fluids, autoxidation reactions, and hy-
drocarbon pyrolysis.
Copyright ChE Division ASEE 1990

the students to develop problem-solving and life-long
learning skills, to think creatively and innovatively,
and to exercise engineering judgment.
This paper describes my experience in implement-
ing an open-ended problem in our junior-level chemi-
cal reaction engineering class. The problem, which in-
volves evaluating and designing a reactor for destroy-
ing organic compounds in an aqueous waste stream,
is one that could be easily and profitably used at other

The open-ended problem placed the students in the
chemical reaction engineering group of a multi-
national chemical processing corporation. Their com-
pany generated aqueous waste streams that needed
to be treated before being discharged into the environ-
ment. Incineration was presently being used. On De-
cember 7, 1988, the CEO of the company read a short
article in the New York Times (Figure 1) about an
alternative method of treating wastewater streams
that involved reacting the organic constituents with
oxygen at elevated temperatures and pressures. He
wanted to know if this technology, termed wet oxida-
tion, was something his company should be using.
After trickling down through a few levels of manage-
ment, the assignment eventually reached the reaction
engineering group (i.e., the students). The groups'
stated mission was to evaluate the wet-oxidation
technology, make a recommendation about its techni-
cal feasibility, and finally, to size a reactor (or process)
and specify its operating conditions.
The students received no information other than
the scenario above and a copy of the New York Times
article. There were no restrictions on their use of out-
side sources of information (e.g., the library, industry,
government agencies, personal contacts, etc.) so prog-
ress down this avenue was limited only by their imagi-
nation and initiative. Another available pathway to
information was their corporation's Technical Service


This paper describes my experience in implementing an open-ended problem in our junior-level chemical
reaction engineering class. [It] involves evaluating and designing a reactor for destroying organic compounds
in an aqueous waste stream, ... [and] could be easily and profitably used at other universities.


Treating Waste
5,000 Feet Down
f a wet waste material, like
sewage sludge, is mixed with
oxygen and placed under high
pressure, it undergoes a
process that chemists call wet
oxidation. The sludge, whose
disposal is becoming a burden
to more and more municipal
sewage plants, is converted to
relatively clean water and
sterile ash.
Such processes, when
carried out on the earth's
surface, require elaborate
vessels under high pressure,
special pumps and ample
acreage for buildings and
equipment. But a Dallas
company, the Oxidyne Group
Inc., has developed a system
that moves the process to the
bottom of a well 5,000 feet
underground, where it is
carried out in a scaled reactor
In the process, sludge is
pumped to the bottom of the
well. Because of the weight of
the sludge coming down the
pipe, pressures at the bottom
of the well can exceed 2.000
pounds per square inch.
Oxygen is sent down through
another pipe and the wet
oxidation begins.
Raw sludge is constantly
pumped into the system and
treated water and ash come
out. Wet oxidation produces
considerable heat, some of
which can be used to drive the

Sewage Treated
Sludge Water
or Other _

I .

Reactor ea

Vessel 5.00 feel
Casing '

About 5.000 feet
2.000 psi
550 degrees Fahrenheit

Copyright 01988 by The New York Times Company.
Reprinted by permission.


Department. This department would conduct experi-
mental work for them, but the students had to define
clearly the precise experiments they wanted done and
the data they desired to be reported. Additionally,
the Technical Services Department conducted experi-
ments only in response to written memos directed to
the Technical Services Director.
Note that the scenario described above was not
intended to represent the way a real corporation oper-
ates. Likewise, the data used in this problem (pre-
sented in the next section) were not necessarily in-
tended to mimic those associated with a genuine

hazardous waste problem. Rather, the goal was to de-
velop an open-ended problem in chemical reaction en-
gineering of sufficient complexity to challenge the stu-
dents without simultaneously overwhelming them.


Background Information

The students' initial activity involved gathering in-
formation about wet oxidation in general, and the
Oxidyne process mentioned in the New York Times
article in particular. Several groups called or wrote to
Oxidyne to learn more about their process technology
and its applicability to their particular waste stream.
Other groups resorted to the library in search of back-
ground information on wet oxidation and vertical, un-
derground wet oxidation reactors. Although the liter-
ature provides limited descriptions of underground
oxidation reactors [1,2], it is rich in general descrip-
tions of wet oxidation processes [3-8]. Of course, the
presence of this information in the literature did not
mean that the students, who apparently had little
training in performing literature searches, would find
it. Indeed, very few groups were adept at locating the
relevant papers and patents.

The Search for Data

All of the groups realized that they needed much
more data than they initially received in the problem
statement. In memos to the Technical Service Direc-
tor, they requested essential data such as the flow
rate, density, temperature, and composition of the
aqueous waste stream and the concentrations of the
various components. I played the role of the Technical
Services Director, but this assignment could also be
delegated to a teaching assistant if desired. For this
problem, I specified a wastewater stream at ambient
temperature flowing at 30 liters/minute. The stream
contained 1% each of phenol, chlorophenol, and acetic
acid. The precise composition of the stream is, of
course, arbitrary, but it is for these three compounds
that the literature [5, 9-14] provides the most kinetics
data for the wet oxidation reactions. One perceptive
group realized that the component concentrations in a
real process could exhibit fluctuations even though the
process was nominally at a steady state. They sent a
memo asking whether such variations occurred and if
so, what their magnitude was. To avoid introducing


unnecessary complexity into the problem I told them
that the variations in concentration were sufficiently
small that they could be safely neglected.
Another piece of information that the students
needed was the maximum permissible concentrations
of the organic in the reactor effluent. Different
groups took different approaches to obtaining this in-
formation. Nearly every group did some library re-
search in an attempt to find environmentally accept-
able discharge levels for phenol, chlorophenol, and
acetic acid. Most groups, however, found an apparent
lack of readily available, specific guidelines. Some
groups contacted the State of Michigan Department
of Natural Resources for state regulations, others con-
tacted the EPA for Federal regulations, still other
groups contacted environmental engineers in local in-
dustries (i.e., Dow Chemical), and one group con-
tacted the Ann Arbor Waste Water Treatment Plant.
Through these and similar efforts the students were
able to select reasonable effluent concentrations for
the three organic constituents of interest in this
At this point, reaction rate data for the wet oxida-
tion of phenol, chlorophenol, and acetic acid were the
only missing pieces of information. Interestingly, only
one group recognized that the library was a rich
source of reaction rate data, and this group, after a
thorough literature search on wet oxidation, was able
to obtain sufficient literature data to proceed with the
reactor design. In fact, this group was so intent on
tracking down all possible literature sources that
when they found a reference to a MS thesis on oxida-
tion in supercritical water [14] they contacted the Uni-
versity of California at Berkeley, where the research
was conducted, to obtain the author's current address
and phone number so that they could consult with him
and obtain a copy of his thesis. The members of this
group were rewarded for their independence and for
realizing that the library, and not the laboratory, is
the first place to look for kinetics data.
The other 19 groups relied on the Technical Serv-
ices Department as their primary source of kinetics
data. These groups submitted memos outlining the ex-
perimental conditions to be used and the data to be
taken. With very few exceptions, the groups' first at-
tempts at identifying conditions that would produce
useful rate data were unsuccessful. They typically
selected initial reactant concentrations that were too
high to allow for isothermal operation of a laboratory
reactor (the wet-oxidation reaction is very exother-
mic) or combinations of temperature and residence
time that led to very high conversions at very short
times (oxidation reactions are very rapid at elevated
temperatures). An additional problem that some

groups encountered was that they requested data that
were not as useful as they had envisioned. For exam-
ple, one group requested that the Technical Services
Department run a wet oxidation reaction in an isother-
mal CSTR, sample the liquid phase at specified times,
and identify and determine the concentrations of the
different components. They were planning to use the
concentration vs. time data to derive the reaction rate
laws. Of course, concentrations do not change with
time in a steady-state CSTR; thus the reply memo
from the Technical Services Director showed that the
component concentrations in the effluent stream,
though lower than those in the feed stream, remained
time invariant. Upon examining the reply memo, the
group eventually realized its mistake. The next memo
requested experiments in a batch reactor wherein con-
centrations do change with time.
The groups' requests for reaction rate data, expec-
tedly, covered a wide range of temperatures, pres-
sures, and initial concentrations. To accommodate
each request precisely would have been impossible
without extensive laboratory work. Thus, when a
group identified experimental conditions that could
lead to the acquisition of useful kinetics data, my reply
memo consisted of a handout containing much of the
literature data available for the wet oxidation of
phenol [5, 9-12], chlorophenol [5, 11-13], and acetic
acid [14], the three compounds of interest in this prob-
lem. The experimental conditions under which these
data were taken covered temperatures from 185 to
4450 C, pressures from 54 to 240 atm, and initial reac-
tant concentrations from about 50 to 12,000 ppm. It
included data obtained from both batch and plug-flow
laboratory reactors.
Because the data given to the students were real
experimental data taken directly from the literature,
they reflected experimental uncertainties, and they
contained occasional bad points. Furthermore, be-
cause I used different data sets taken by different
investigators under different experimental conditions
and interpreted using different assumptions, the col-
lection of data given to the students was not entirely
internally consistent. Thus, in interpreting their kine-
tics data and deriving reaction rate laws, the students
had to exercise judgment and decide which data sets
were the most reliable for their design calculations.

Reactor Configurations and Operating Conditions
Having obtained all the necessary flow rates, com-
positions, and kinetics data, the students next began
to consider the issues involved in selecting and design-
ing a wet-oxidation reactor. Because the New York
Times article described a vertical oxidation reactor


that descends 5,000 feet below the surface of the
earth, all of the student groups took this reactor con-
figuration as their starting point. Most groups began
trying to model such a reactor using a combination of
ideal reactors. Several groups contacted Oxidyne for
more information about their reactor systems and for
assistance in their modeling efforts. These initial mod-
eling activities revealed that the students perceived
their assignment to be sizing a vertical, underground
oxidation reactor. By unnecessarily confining them-
selves to a specific reactor configuration so early in
the solution process, however, they failed to see the
broader issues involved in the problem. Therefore, I
spent a few minutes of class time encouraging them
to think about the real problem (which was not neces-
sarily the same as the stated problem) in which the
CEO was interested. After some discussion along
these lines the students began to realize that the real
problem was not simply to size an underground oxida-
tion reactor, but rather for their company to make its
products without experiencing any adverse environ-
mental consequences. Upon identifying the real prob-
lem, many groups began to develop ideas such as mod-
ifying the manufacturing process to minimize the
amount of waste produced, developing new
technologies that generated less or more easily
treated wastes, separating and recovering the compo-
nents in the waste stream, and exploring alternate
means of wastewater treatment (e.g., ozonation,
biodegradation, and the use of catalysts). Not all
groups explored all these themes, of course, but all of
them did at least broaden their scope from the initially
narrow one that considered only the underground
After examining several alternative solutions to
the real problem, many groups concluded that because
the wastewater stream flow rate was low, and because
it was relatively dilute there were no real advantages
in using an underground reactor. These groups then
proceeded to design a conventional above-ground
reactor suitable for wet oxidation. They used either a
PFR or a CSTR as the basis for their design calcula-
The majority of the groups, however, decided that
an underground oxidation reactor remained as the
best possible solution. These groups sent memos to
the Technical Services Director requesting, among
other things, the location of the chemical plant that
generated the wastes, the composition of the earth's
crust at the plant site, the thermal diffusivity of the
ground, and the population density around the site. I
tried to keep the problem general and also minimize
the amount of data I had to manufacture by replying

that because the corporation was multinational it
sought a technology that could be implemented any-
where in the inhabited world.
Most groups demonstrated a reluctance to deviate
from the operating conditions of 2000 psi and 550F
(2880C) noted in the New York Times article, and their
final designs typically specified conditions near those.
Although the students realized that reaction rates in-
creased with temperature, they seemed quite hesitant
to specify higher reactor temperatures. Interestingly,
a few groups thought that the critical temperature of
water, which is 374C, posed some sort of ther-
modynamic barrier that dare not be crossed during
the reaction. These groups carefully designed their
reactors so as not to exceed this critical temperature.

After some discussion the students began
to realize that the real problem was not simply
to size an underground oxidation reactor, but
rather for their company to make its products
without experiencing any adverse
environmental consequences.

The origin of this mistaken impression is unclear, es-
pecially considering that the students were given ex-
perimental rate data taken at supercritical conditions
[13,14]. Several groups, fortunately, realized that the
critical temperature was not a barrier, and they
selected high temperatures that led to high reaction
rates. These groups, through reading the literature
[1,13-17], came to appreciate the unique advantages
that supercritical operation offers.

The fact that the assigned problem was truly open-
ended in the sense that multiple solutions existed was
verified by the diversity in final designs. Of the
twenty groups working on the problem, eleven se-
lected underground oxidation reactors such as the one
described in the New York Times article. Eight
groups decided that the underground reactor afforded
few advantages for this particular application, and
they selected a more conventional above-ground flow
reactor (e.g., PFR or CSTR). One group apparently
found the decision of reactor placement a difficult one,
so these students designed a reactor that they claimed
could be operated either horizontally above the
ground or vertically underground to meet the plant
manager's preference. It is interesting to note that
the majority of the groups retained the vertical, un-
derground design and the operating conditions high-
lighted in the brief New York Times article. I think it
is unlikely that any of these groups would have recom-


mended such a reactor configuration had they not first
read the newspaper clipping. Thus, in this case, the
final solution tended to reflect the initial information
given to the students.
The final reactor designs also exhibited tremend-
ous variety in their mode of operation (e.g., isother-
mal, adiabatic, and non-adiabatic reactors with heat
transfer were all recommended) and operating tem-
peratures (170 7270C). The calculated reactor vol-
umes varied by six orders of magnitude as the small-
est reactor volume was 0.845 liters (roughly the size
of a pop bottle) and the largest was 494,000 liters
(roughly the size of three large railroad tank cars).
The fact that different groups arrived at very differ-
ent final designs can be attributed primarily to the
different interpretations of the experimental kinetics
data, the different operating conditions and reactors
selected, and the different effluent concentrations
deemed to be acceptable.


This open-ended problem gave the students an op-
portunity to use and develop several different types
of skills. Indeed, a thorough solution to the problem
required the students to exercise their technical,
problem-solving, and communication skills.

Technical Skills Technical skills were developed
via the students' application of some of the key concepts of
chemical reaction engineering. Topics such as modeling ideal
reactors, obtaining and analyzing experimental rate data,
performing energy balances for an exothermic reaction, han-
dling situations with multiple reactions, and dealing with
transport effects in gas-liquid reaction systems were all com-
ponents of the open-ended problem solution. Several of the
groups also wrote computer programs to solve the simultane-
ous mole and energy balances that arise in this design prob-
Problem-Solving Skills In addition topracticing
the application of course-specific technical topics, the stu-
dents also exercised more generic problem-solving skills. For
example, they gained an appreciation for the importance of
problem identification and definition. The exercise in distin-
guishing between the real problem and the apparent prob-
lem, which incidently is unique to open-ended problems,
helped the students to generate alternative solutions to the
one initially identified by the CEO. This open-ended prob-
lem also forced the students to adopt and develop a problem
solving strategy. They had to identify the important issues
involved in the problem, plan a means of addressing those
issues, and plan an experimental program (or literature
search) for obtaining the required data. The problem also
allowed the students to be creative, innovative, and resource-
ful. Most of the students enjoyed this aspect of the problem
for they rarely have this freedom when solving more tradi-
tional homework exercises. Furthermore, through this open-
ended problem, the students gained an appreciation for the
issues involved in solving a complex problem. They realized
that a completely rigorous approach to the design of a wet-

oxidation reactor for a multicomponent mixture was beyond
their level of knowledge and beyond the scope of the course.
Thus, the students had to decide where they could make
assumptions that would simplify the problem without seri-
ously compromising the final solution. Not all groups were
equally adept at this task, however, and several groups seemed
perfectly comfortable making assumptions that simplified
the problem but did not reflect reality. One final skill that
this problem afforded the students was the opportunity to
sharpen their engineering judgement. The groups had to
decide what type of reactor to use, what operating conditions
to select, whether or not to use an underground reactor, and
how to analyze their ambiguous reaction rate data.
Communication Skills The structure of this se-
mester-long open-ended problem was such that it included a
large amount, and different types, of writing. For instance,
the students wrote one-page memos to the Technical Services
Director when they needed experimental data. They also
submitted a two-page (maximum) progress report around
the middle of the semester, and then a comprehensive final
report at the end of the semester. This emphasis on technical
writing was intentional. In fact, portions of two different
class lectures were devoted to a discussion of the key ele-
ments of good technical writing, and the students also had
an in-class exercise wherein they revised a poorly written
paragraph taken from one of their peers progress reports. To
provide the students with an additional resource, I also used
The Elements of Style by Strunk and White as a required
text for the course.
I encouraged the students to write each memo and
report thoughtfully by returning for revision any written
document that contained more than three grammatical or
stylistic errors (e.g., sentence fragments, lack ofsubject-verb
agreement, excessive use of passive voice, etc.). As expected,
revisions were frequent early in the semester. I wanted the
students to learn from their mistakes, however, and not nec-
essarily be punished for them. Therefore, revising a memo
did not affect the student's grade, but merely delayed their
receipt of experimental results from the Technical Services
Department. A revision of the progress report likewise car-
ried no penalty other than the extra work associated with
turning in the report a second time. Revision of the final
report, however, did lead to a ten percent reduction in the
group's score for the project. Only four of the twenty groups
had to revise their final reports, however, and even those
four reports showed signs of having been written carefully
and thoughtfully.


The open-ended problem described in this paper
provided a good opportunity for the students to apply
key elements of chemical reaction engineering in addi-
tion to developing more generic problem solving skills
and communication skills. Most of the students en-
joyed the problem and the departure it presented
from the more conventional homework exercises.
One point that resonated from the student evalua-
tions at the end of the semester was that the course,
as a whole, involved too much work. I recognized that
this open-ended problem would require a significant
effort from the students, so I covered one less chapter


in the text than I had previously covered in the
course. Apparently, however, the omission of this one
chapter did not compensate for the addition of the
open-ended problem. Therefore, care must be taken
to ensure that the incorporation of a major open-ended
problem is accompanied by the reduction of other as-
signments so that the students are not overloaded.
Fortunately, the open-ended problem described in
this paper is sufficiently flexible that it can be mod-
ified to suit an instructor's preferences and the time
available in the course. For instance, the amount of
student effort required can be reduced by providing
literature data [5, 9-14] for the kinetics, specifying the
desired concentration of organic in the effluent, or
specifying a single organic pollutant in the wastewater
stream rather than a multi-component mixture.

H. Scott Fogler initiated the departmental effort
to incorporate open-ended problems in the curriculum,
and Brice Carnahan originally identified the New York
Times article referenced in this paper as the basis for
a problem in reaction engineering. Tom Thornton per-
formed the literature search and obtained the kinetics
data used in this open-ended problem.

1. Titmas, J.A., "Method and Apparatus for Conducting Chemi-
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13. Yang, H.A., and C.A. Eckert, "Homogeneous Catalysis in
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Ind. Eng. Chem. Res., 27, 2009 (1988)
14. Wightman, T.J., "Studies in Supercritical Wet Air Oxida-
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15. Thomason, T.B., and M. Modell, "Supercritical Water De-
struction of Aqueous Wastes," Hazard. Waste., 1, 453 (1984)
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(1985) 1

book review

(Second Edition)
Raymond B. Seymour and Charles E. Carraher, Jr.
Marcel Dekker, Inc., New York, 10016
720 pages, $45.00 (1988)

Reviewed by
William J. Koros
The University of Texas

This book is an updated version of a text which
was first published some years ago by McGraw-Hill.
This second edition comprises the eleventh volume in
a series of undergraduate texts dealing with a broad
range of topics in chemistry. As is pointed out in the
forward to the book, written by Herman Mark, this
new edition is quite up-to-date in terms of topical
coverage, but without unnecessary complications. The
book is easily read and has an almost conversational
tone to it. One can imagine sitting across from the two
authors (whose broad knowledge of polymer science is
well-known) and having the book unfold in a casual,
but still logical, fashion.
The revised text includes a number of new top-
ics, and the authors note that the book meets the ACS
guidelines for topical coverage in an introductory
polymer chemistry course. A glossary and series of
questions related to the material is given at the end of
each chapter. The questions at the end of the chapter
are a plus for the book since it is difficult to obtain good
homework exercises in the polymer field without
actually synthesizing them oneself. Nevertheless,
while these exercises are useful, they are mostly
discussable in nature and do not satisfy the persistent
need for a really good compilation of computational
problems to illustrate principles discussed in a poly-
mer text.
As must be the case whenever one considers a
wide range of topics and is committed to keeping the
page-count within bounds, none ofthe topics is treated
in any detail. The title, Polymer Chemistry, is not
Continued on page 167.




An Educational Need

University of Dayton
Dayton, Ohio 45469

HEMICAL ENGINEERING is a dynamic discipline.
However, the petroleum and traditional chemical in-
dustries are no longer expanding and the result is
dwindling employment opportunities for chemical en-
gineers. Although chemical engineers will continue to
play a major role in these industries, the future of chem-
ical engineering can and should be enhanced by identify-
ing new areas in which students can be appropriately
trained. This would be mutually beneficial to both stu-
dents and industry since it would not only expand the
employment horizon for students but would also supply
industry with engineers for new technologies.
Several emerging technologies (including biochemi-
cal/biomedical engineering, microcomputer applications,
process control and safety, synfuels, and advanced ma-
terials) have been identified as natural extensions to
traditional chemical engineering [1,2]. This paper deals
mainly with incorporating the concepts and applications
of advanced composite materials into existing chemical
engineering programs. Ideally, the chemical engineer-
ing curricula should have at least four electives which
allow a concentration in one of the emerging
technologies listed above [3]. However, due to general
education requirements and/or other constraints, chem-
ical engineering programs do not allow much flexibility
for the selection of technical electives. The solution pro-
posed here would expose students to various areas of
composite materials, and that, in turn, would expand
their employment opportunities to the aerospace and
automotive industries.

This paper deals mainly with
incorporating the concepts and applications
of advanced composite materials into existing
chemical engineering programs.

Composite materials consist of reinforcing particu-
lates or fibers such as glass, graphite, metals, or
ceramics in a matrix that can be polymeric, metallic, or
ceramic. The type and composition of the constituents
and the processing procedure can be varied in order to
tailor the composite properties. These properties, which
are superior to those of the individual constituents, in-
clude a high strength-to-density ratio, a high stiffness-
to-density ratio, high or low conductivity, and resistance
to corrosion, fatigue, and stress rupture.
The industrial applications of composite materials
span a wide range from advanced satellites to the simple
golf club. Applications include aircraft components such
as wings, helicopter blades, satellites, missiles, and en-
gine components. In the automotive industry, body
panels, brackets, drive shafts, and springs are made of
composites. The consumer industry uses composites in
boats and in sporting goods such as racquets, golf clubs,
and fishing rods.
The processing methods vary depending on the type
of reinforcement and matrix. For thermoplastic mate-
rials, the techniques include injection molding, compres-
sion molding, and cold stamping. Thermoset processing
may employ contact molding, matched die molding,
reaction injection molding, pultrusion, filament winding,
or vacuum bag autoclave molding.

Tony E. Saliba is an assistantprofessor of chemical
and materials engineering at the University of Day-
ton. He has conducted research on contracts from
Wright Aeronautical Materials Laboratory, McDon-
nell Aircraft Company, The Edison Materials Tech-
nology Center, and Chrysler Motors Corporation. He
has over thirty publications in the area of process
modeling and control of advanced composite mate-

SC ChE D AS 1990
0 Copyyght ChE Division ASEE 1990

James A. Snide is Director of the Graduate Materi-
als Engineering program at the University of Dayton.
He served as a Visiting Scientist at the AFWAL
Materials Laboratory to help develop a laboratory
capability to conduct failure analyses of advanced
composite materials. His most recent work has been
in the evaluation of failure modes of composite
Materials used in automotive applications, and he
has compiled a book on materials and process


There is a critical need for personnel with some
training in the design and processing of composite mate-
rials. The current demand is estimated at eight hundred
engineers while the supply is only eighty to one hundred
fifty [4,5]. The composite industry is believed to be
growing at an annual rate of twenty percent [4]. A U.S.
Office of Technology Assessment report indicated that
22 million pounds of advanced composites were pro-
duced worldwide in 1984 and estimated that the produc-
tion would increase to 200 million pounds by year 2000
[4]. Most composite education is obtained in graduate
schools, with most of the graduates working in research
and development. Newly graduated BS engineers are
still needed for design and development, manufacturing,
and technical sales (where forty percent of the available
jobs are) [6].
One undergraduate program in composite mate-
rials engineering has been started at Winona State
University. However, this one program cannot meet
the demand in view of the tremendous growth of the
composite materials industry (raw materials usage by
the composite industry is projected to grow to $10
billion by 1992 [4]). Only a few other schools have
started similar programs, and most other programs
have curricula with only one, or no, technical elec-
tives. An alternative approach would be to incorpo-
rate the various concepts into existing classes with
example problems, lecture materials, and/or class pro-
Several traditional chemical engineering principles
are essential in the composite materials industry. The
processing of composites consists of applying heat and
pressure. The heat is needed to initiate chemical or
physical changes, and the pressure is needed to com-
pact the product to its final shape. Heat transfer
theories are needed to understand and to design the
various processes. Fluid flow theory is needed to pre-

First Chemical Engineering Introductory Class
1. Introduction to Composite Materials
A. Definition
B. Classes of composites
C. Industrial applications
D. Whycomposites
E. Specific properties
F. Brief history

2. Constituent Materials
A. Fibers/ Reinforcements
B. Matrix Materials

diet resin flow, which thus predicts suitable process-
ing parameters and results in appropriate fiber and
resin content and distribution. Mass transfer concepts
are necessary to study environmental effects of mois-
ture and solvents during the composite part as well as
to manage void formation and growth during the man-
ufacturing process. Chemical kinetics information is re-
quired to follow the chemical reactions in thermosets
and crystallization in thermoplastics as well as to de-
termine the heat generation rate. Traditional process
design principles can be applied to product, process,
and plant design. Many chemical engineering concepts
are used in composite materials engineering. Our
proposal is to introduce the students to examples de-
picting the application of basic engineering concepts
to composite materials and to encourage the students
to become familiar with the terminology, thus provid-
ing them with a starting point for further learning.

The application of chemical engineering principles
to composite materials design and manufacturing can
be included in several traditional chemical engineering
classes. As shown in Table 1, a brief introduction to
the role materials play in a typical chemical engineer-
ing assignment, followed by an introduction to compo-
site materials, can be covered in an introductory class
in chemical engineering.
The concepts outlined in Table 2 can be introduced

Transport Phenomena

I. FluidMechanics
1. Resin Flow During Autoclave Cure
A. Flow between parallel plates (University of Michigan Model)
B. Flow around plates and cylinders (McDonnell Douglas)
C. Flow through porous media (University of Dayton, MIT)
D. Resin loss, compaction rate, and fiber volume fraction
2. Other Processes
A. Pultrusion
B. Extrusion

II. Heat Transfer
1. Thermophysical Properties of Anisotropic Systems
A. Resistance analogy
B. Volume average
C. Empirical formula
D. Transport properties
2. Heat Transfer Codes
A. Modeling heat transfer in an autoclave convectivee BC)
B. Heat transfer in a press (temperature and heat flux BC)
C. Heatgeneration term due to exothermic chemical reactions
D. Coupled heat transfer and fluid flow in an extruder

Ill. Mass Transfer
1. Diffusion of Water/Solvents in Composites
2. Void Nucleation and Growth


in fluid mechanics, heat and mass transfer, or an equi-
valent transport phenomena class. The basic princi-
ples are still the same; the applications are different.
The topics cover modeling of the transport processes
and the determination of various composite ther-
mophysical and dimensional properties. In a transport
phenomena laboratory, measurement of composite
materials transport properties can be implemented as
shown in Table 3. Other experiments for temperature
and pressure measurements can also be incorporated.
The basic concepts pertaining to polymerization
and crystallization kinetics described in Table 4 can be
covered in a kinetics or a reactor design class. These
topics deal with reaction mechanisms as well as the
introduction of nucleation and growth rate effects on
the crystallization kinetics.
The composite manufacturing techniques listed in
Table 5 can be introduced in a unit operations class
and/or laboratory. Studying the effect of the various
process parameters on the properties of the final prod-
uct can help students become familiar with the unit
operation itself and manufacturing aspect of composite

Transport Phenomena Laboratory

In this laboratory, experiments related to composite materials can be
developed and used. These could include:

* Measurement of temperature distributions during the cure of a
composite material and comparison with predicted temperatures
from heat transfer calculations.

Estimation of the diffusion coefficient of moisture in composite
using percentweight gain measurements and available diffusion
codes. (This experiment will require several weeks.)

Viscosity measurement during the cure of composite materials
using rheometrics, dielectric monitoring or acoustic attenuation

Measurement of the apparent thermal conductivity of composite
materials using temperature and heat flow measurements.

Kinetics and Reactor Design

1. Polymer Kinetics
A. Polycondensation reactions
B. Free radical addition polymerization
C. Non-radical addition polymerization
D. Copolymerization
E. Available kinetic models

2. Crystallization Kinetics
A. Avrami equation
B. Avrami equation-based polymer crystallization models

Perhaps the most flexible area for the introduction
of composite materials applications is in the design
area. Most universities have two design classes. The
first design class, covering an overview of general de-
sign considerations and the use of economic factors
and optimization as applied to traditional chemical en-
gineering design problems, can remain unchanged.
The second design class can be modified to introduce
product and process design requirements as applied
to composite materials and to implement a composite
segment with applications in the aerospace, automo-
tive, and consumer industries. A design class is an
ideal place for a class project that incorporates and
summarizes the concepts learned in the first three
years. The project could consist of choosing a specific
novel application for an advanced composite. The
product requirements for the specific application, as
well as the manufacturing process, could then be iden-

Unit Operations

Unit operations used in composite materials manufacturing include:
1. Filiment Winding
2. Prepreg Layup
3. Autoclave Molding
4. Injection Molding
5. Compression Molding

Product and Process Design

1. Process Modeling and Optimization

2. Material Selection Criteria
A. Geometric considerations
B. Properties requirements
C. Cosmetic requirements
D. Processability/maintainability
E. Product quality
F. Cost

3. DesignConcepts
A. Cost of design and manufacturing
B. Coordination between design, tooling, and manufacturing
C. Product quality assessment and control
D. Mathematical analysis
E. Joint design
F. Design databases
G. Computer programs for design (LAMRANK, CLASSIC)
H. Life-cycle analysis

4. Project
A. Justification for using composite materials
B. Constituent materials selection
C. Manufacturing techniques chosen
D. Meeting design requirements
E. Quality assurance
F. Modifications and recommendations


tified [7,8]. The concepts covered in this class and the
project outline are listed in Table 6.
Finally, a seminar can be used to invite chemical
engineers from the composite industries to share their
experiences and to introduce the students to various
composite industry problems and solutions.


Both the mechanical behavior of composite mate-
rials and the effect of processing parameters on the
mechanical properties are important areas of compos-
ite materials manufacturing and design. Although the
mechanics of composites topics are more appropriate
in a mechanical engineering curriculum, chemical en-
gineering students might choose to take a strength of
materials class where the concepts of anisotrophy and
mechanical behavior are introduced.
Despite the importance of composite materials and
the essential need for engineers knowledgeable in this
emerging technology, introducing composite materials
topics into the existing curricula should be done with-
out compromising the basic engineering sciences. The
principles currently covered should remain intact, but
the examples and the application of these principles
could be tailored to composite materials.
In order to implement the plan, the department
should have faculty members working in the area of
composite materials who can bring their experience
and expertise to the classroom (our department has
five faculty members who work in the polymer/compos-
ite materials area). A department looking for a new
direction, but without expertise in the field, could re-
train faculty who have an interest in this area through
short courses, conferences, and industry/government
facility summer internships. Another mechanism for
implementation could be through the use of part-time
faculty who have extensive experience in the compos-
ite materials industry.


A strategy for introducing composite materials
concepts into existing classes has been proposed. Im-
plementing the application of basic chemical engineer-
ing principles to composite materials is necessary if
we are to meet the demand for chemical engineers
knowledgeable in this emerging technology. It is an
alternative that can be used in schools where concen-
trations in the areas of new technologies cannot be
introduced. Finally, this approach will not require re-
accreditation since classes and the basic principles re-
main the same; only the examples and the applications
would change.


1. Eisen, E.O., "A Survey on Emerging Technologies in Chemi-
cal Engineering," presented at the American Institute of
Chemical Engineers Annual Meeting, Chicago, IL (1985)
2. National Research Council, Frontiers in Chemical En-
gineering, Executive Summary and Recommendations, Na-
tional Academy Press, Washington, DC (1988)
3. Saliba, T.E., and J.A. Snide, "Introducing Concentrations in
Emerging Technologies in Traditional Disciplines," Univer-
sity of Dayton; to be published
4. Sponseller, M., "Cash in on the Composites Revolution,"
Graduating Engineer, McGraw-Hill, New York (1988)
5. Saliba, T.E., and J.T. Johnson, "Composite Materials: Edu-
cational Opportunites," presented at the 2YC3 Joint US/
Canada Conference, Toronto, Canada, June (1988)
6. U.S. Office of Technology Assessment, New Structural
Materials Technology, Washington, DC (1986)
7. Browning, C.E., "Composite Materials...," class notes, Uni-
versity of Dayton, Dayton, OH (1985)
8. Saliba, T.E., and J.M. Whitney, "Curriculum for a Bachelor
of Science in Composite Materials Engineering," Winona
State University, Winona, MN (19878) 0

books received

Advanced Inorganic Chemistry, 5th Edition, by F. A. Cotton and G.
Wilkinson; John Wiley & Sons, Inc., 1 Wiley Dr., Somerset,
NJ 08875-1272; (1988) 1455 pages, $44.95
Large Scale Cell Culture Technology, Edited by B. K. Lydersen;
Oxford University Press, 200 Madison Ave., New York, NY
10016; (1988) 252 pages $69.00
Plastics Additives, 2nd Edition, by Gachter and Muller; Oxford
University Press, 200 Madison Avenue., New York, NY
10157-0913; (1988) 754 pages $80.00
Active Carbon, by Bansal, Donnet, and Stoeckli; Marcel Dekker,
Inc., 270 Madison Ave., New York, NY 10016; (1988) 496
pages $125.00
Particulate Phenomena and Multiphase Transport (5 volumes),
Verizoglu(ed); Hemisphere Publishing Co., 79 MadisonAve.,
New York, NY 10016; (1988) 3072 pages, $700.00
Catalysis of Organic Reactions, by P. N. Rylander, H. Greenfield,
and R. L. Augustine (eds); Marcel Dekker, Inc., 270 Madison
Ave., New York, NY 10016; (1988) 456 pages, $99.75
HEDH, Heat Exchanger Design Handbook, Supplement 4, edited
by Schlunder; Hemisphere Publishing Co., 79 Madison Ave.,
New York, NY 10016-7892; (1988) 512 pages, $140.00
Innovation in Process Energy Utilization, edited by Rogers, Steel,
etal; Hemisphere Publishing Corporation, 79 Madison Ave.,
New York, NY 10016-7892; 445 pages, $98.50 (1988)
Fluid Mixing III, Edited by N. Harnby; Hemisphere Publishing
Co., 79 Madison Ave., New York, NY 10016; (1988)290 pages,
Advances in Thermal Modeling of Electronic Components and
Systems, Vol. 1, by Bar-Cohen and Kraus; Hemisphere Pub-
lishing Corporation, 79 Madison Ave., New York, NY 10016-
7892; 469 pages, $90.00 (1988)






Northeastern University
Boston, MA 02115

T INCREASINGLY APPEARS that high school stu-
dents who have the opportunity to take science
and mathematics courses which lead to careers in
technology fail to do so. This national dilemma may
stem, in part, from the fact that students simply have
no idea of the socially positive nature of technological
contributions. Those students who avoid taking the
most challenging mathematics and science courses
while in high school may not know how exciting the
practical results of their knowledge can be, or how
useful their contributions could be. Briefly, high
school students need to be given a more pragmatic
grasp and understanding of technology in addition to
guidance concerning their career paths. With some
practical understanding of technology, these same stu-
dents might then pursue advanced science and math
courses while in high school.

We have been investigating ways to introduce
applications of modern biotechnology to high school
students, with the objective of incorporating these ap-
plications into high school science courses. To date we
have carried out two quarters of a pilot program,
meeting after school with local ninth and tenth grad-
ers. The sessions in the first quarter were one hour
long and were of a "show and tell" nature. (About
twenty-five students began this first group and about
twenty completed the quarter). For the second quar-
ter, we held two-hour sessions in which we introduced
a topic and then conducted a demonstration which in-
cluded some measurement. This was followed by an
"experiment" conducted with groups of three to four
students. In all cases, the sessions closed with a writ-
Copyright ChE Dilision ASEE 1990

ten quiz and a discussion of the results of the quiz.
This second-quarter pilot program involved two
groups of students, and fifty-two out of sixty-four stu-
dents completed the program and received a certifi-
cate. Moreover, fifteen of the students volunteered to
continue with a summer internship project. We now
believe it is important to also work closely with the
teachers and are planning a summer session for high
school science teachers.
Our objective in conducting this exploratory pro-
ject was to learn how to introduce technology into
high schools. Biotechnology was selected as our theme
because of the background of several of our engineer-
ing faculty in this field, and because this technology
has recently attracted media attention and, we as-

I Donald L. Wise is Cabot Professor of Chemical
Engineering at Northeastern University and Direc-
tor, Center for Biotechnology Engineenng. He has
an industrial and academic background in applied
biotechnology, with specialization in biopolymers,
bioconversions, and bioelectronic systems. He is
the author of more than fifty papers and is the
editor of many reference texts.

Ralph A. Buonopane is an associate professor
and chairman of the department of chemical
engineering at Northeastern University. He has
provided a leadership role in the cooperative
educational program at Northeastern University,
especially working to ensure that the industrial
"co-op" experience of students provides special
on-the-job education.

David C. Blackman is an associate dean of the
college of engineering at Northeastern University
and directs the minorities program there. He has
worked to achieve the highest retention rate of
minority engineering students in the nation.


sumed, student interest. Moreover, biotechnology
cuts across essentially all standard career fields and
is most often interdisciplinary in practical implemen-

The first quarter of the pilot program was initiated
through an established program at Northeastern Uni-
versity which provides academic support to, primar-
ily, minority students. This first quarter of our "Appli-
cations of Biotechnology" program was offered to
tenth graders, and our one-hour session on the topic
was followed by one hour of mathematics for the same
students. Our retention through the quarter of about
twenty students out of the beginning twenty-five was
exceptional when compared to other attempts to pre-
sent topical issues to high school students.
Our pilot program for the second quarter was ini-
tiated when two professors visited a biology teacher
and one of his ninth grade classes at a local high
school. After discussing our plans for a second after-
school pilot course, the biology teacher (with the ap-
proval of his Headmaster) agreed to hand out an appli-
cation form and questionnaire. We had hoped to have
as many as fifteen students enroll but had anticipated
perhaps twelve. We were all surprised when sixty-
four students applied. The biology teacher and others
at the school tried to, but could not, pinpoint the "key"
words in the application that attracted the interest of
so many students.
At this point, because of the large number of appli-
cants, the Headmaster wanted to know what our
criteria would be for accepting the planned-for 12-15
students and rejecting the others. We then decided to
accept all of the applicants and to divide our second
pilot project into two classes to accommodate them.
Each class would have identical presentations and
would meet after school for two hours on Monday and

Our plan was to present approximately a one-hour
informal lecture on a topical subject, with as much
question-and-answer participation as possible. While
some of the classroom discussions also included show-
and-tell demonstrations, most of this first portion of
the two-hour session was used to introduce the techni-
cal topic of the day. As noted previously, we prepared
a typed quiz for the students to take. To save time,
the snack-break was coupled with the written quiz,
enabling an immediate review of the quiz. The second
portion of the session was then devoted to some type

S. high school students need to be given a
more pragmatic grasp and understanding of
technology in addition to guidance
concerning their career paths.

of "hands-on" experimental work which involved some
aspect of quantitative measurement.
A discussion of one particular session will be useful
here. In the session on pharmaceuticals, we demon-
strated "pan agglomeration" or "prilling" of "tiny time
capsules" to the class in the first portion of the session.
In the second portion, students were divided into
groups of three students each, and each group was
given three pairs of pre-pressed tablets, i.e., six tab-
lets, along with a beaker of water. The tablets con-
tained sodium bicarbonate and citric acid, so the reac-
tion, when dropped into water, was a visible efferves-
cent carbon dioxide. It surprised the students to learn
that the tablets had been prepared under 2,000, 4,000,
and 6,000 p.s.i. compression, and therefore they had
significantly different "release" times.
After measuring the timed release of these tablets,
we passed out similar tablets, but with a biopolymer
coating (also demonstrated by spray coating), to dem-
onstrate a long-acting, or "controlled release," sys-
tem. As expected, these time-capsules had a much
longer "lifetime."

A list of the topics covered in each session during
our pilot program follows.

Session 1
Bioconversion of Municipal Solid Waste
In this session we discussed the bioconversion of
municipal solid waste. Under appropriate conditions
certain microorganisms degrade wastes and produce
fuel gas, a valuable by-product. The magnitude of the
problem of disposing of municipal solid waste was re-
viewed using 35mm slides of "dump sites" in different
places throughout the world. Students seemed im-
pressed that substitute natural gas, used in some of
their own homes, could be produced from wastes-
through the action of microorganisms.

Session 2 *
Medical Applications of Plastics
In this session we discussed medical applications
of biopolymers. Biopolymers are special plastics that
are used, for example, as surgical staples, bone


"grout" (a putty-like material used for bone repair),
heart valves, bone splints, etc. We focused, in particu-
lar, on biodegradable plastics used as implantable
long-acting controlled release drug delivery systems.
For this application, a conventional drug (for example,
an antimalarial drug) is blended with a biodegradable
plastic. This drug/polymer matrix is then extruded
into a small thin rod, about the size of a pencil lead.
When this rod is implanted, the drug slowly diffuses
out and, as the polymer biodegrades, a continuous re-
lease of drug occurs, providing protection (in this
example case) against malaria. We used 35mm slides
to illustrate a number of controlled release drug deliv-
ery systems in model animal situations.

Session 3 *
Biopolymers in Concrete
The purpose of this session was to introduce a
novel application of biopolymers, i.e., using a
biopolymer in concrete with the objective of reducing
water permeability. The reasoning was that using a
water soluble plastic in making concrete would reduce
water penetration, resulting in an improved material
for pothole repair. Students, in groups of three, car-
ried out the preparation of concrete in the laboratory.
Samples were prepared with and without biopolymer.
Using similar samples of concrete (prepared earlier
for this class), students observed and recorded com-
pression strength testing on the Instron tester. Most
students were not aware of the technology involved
in considering an improved concrete.

Session 4 *
Production of Bread Yeast
Technology for producing yeast used in making
bread is similar to the technology for producing anti-
biotics and other pharmaceuticals and biologicals.
Using bakers yeast as a model, students carried out
the initial plating of the yeast (many came back the
following week to show their cultures), and they ob-
served the yeast growing in shake flasks and the pro-
duction of yeast in a pilot-plant fermenter. To stress
the importance of being able to measure key paramet-
ers, samples of yeast in the active growth phase were
taken, and students monitored the oxygen uptake
rates. The students showed an interest in actually ob-
serving microorganism-growing situations.

Session 5 *
Prevention of Acid Rain
"Acid rain" is generally believed to be caused by
burning coal which contains substantial amounts of

sulfur. Research work is under way to use enzymes
to clean the organic sulfur from coal. We presented a
demonstration of enzyme activity as well as measure-
ment of sulfur removal. The students recognize the
importance of reducing acid rain and were impressed
by the catalytic activity of enzymes.

Session 6 *
Preparing Pharmaceutical "Tiny Time Capsules"
The technology of pan agglomeration, or "prilling,"
was demonstrated, showing how "tiny time capsules"
are produced from a mixture of powdered phar-
maceutical chemicals. Components of commercial Alka
Seltzer (citric acid and sodium bicarbonate) were
used as a model system. After "prilling," the small
beads were coated or encapsulated with biopolymer,
thus providing for a longer-acting release of the active
ingredients. Prior to the class we had also prepared
(by compression) tablets of citric acid and sodium
bicarbonate, and each student group of three received
three tablets. After placing a tablet into a beaker of
water, the group would determine the time required
for complete dissolution. Since we had prepared the
tablets under different pressues (2000, 4000, and 6000
psi), the time for dissolution varied. The tablets
coated with a polymer were found to have much longer
lifetimes. The students were interested in observing
and learning how selected conventional pharmaceuti-
cals are produced.

Session 7 *
Field Trip to Sewage Treatment Plant
We took a field trip to the Massachusetts Water
Resources Authority sewage treatment plant located
on Deer Island. Plans for the new Boston harbor
cleanup, to be carried out from this facility, were also
reviewed. The tour was directed by a person inti-
mately familiar with all operations of the plant and it
involved site visits to all major aspects of the facility.
Students were impressed with the size of both the
treatment plant and the new composting pilot plant
(for converting sewage sludge residuals into a mate-
rial for organic gardening).

Session 8 *
Food Technology Applications
Three undergraduate chemical engineering stu-
dents presented brief overviews of their special as-
signment dealing with food technology. One student
presented the procedures for concentrating orange
juice, the central step of which is freeze crystalli-
zation. Comparisons were made between preparing


concentrated orange juice (freezing from water) and
shipping "not from concentrate." Another student
considered freeze drying of meat such as that used in
making certain soup mixes. There was a lively discus-
sion about food preservation techniques, including the
use of chemical preservatives and methods used in
other countries.

Session 9 *
Unit Operations
In this session, the students were introduced to
process systems and "scale-up," i.e., the consideration
of how chemical and biochemical products are man-
ufactured on a larger, more practical scale. Unit oper-
ations consist of singular processing units which, when
combined, make up essentially all chemical/biochem-
ical production plants. The classroom discussion
stressed the importance of measurements of fluid
flow, temperature, etc. The laboratory experiment,
using a completely computer-controlled humidification
unit, involved groups of students monitoring changes
in input variables and subsequent changes in the sys-
tem output.
Session 10
"CMA" Deicing Salt
Calcium magnesium acetate, or "CMA," is a non-
corrosion, non-polluting organic deicing salt (de-
veloped under sponsorship of the Federal Highway
Administration) that is produced from dolomitic lime-
stone and acetic acid. In this session we first reviewed
how microorganisms may be used to directly produce
many organic chemicals (lactic acid, ethanol, methane/
carbon dioxide, acetic acid, etc.). Using CMA as an
example, we discussed how further processing of the
fermentation product (acetic acid, in this case) may be
required. Following an overall description of the
conversion of organic wastes to CMA, liquid-liquid ex-
traction of acetic acid from fermenter broth was dem-
onstrated in the classroom. Then each group of three
students received a sample of the extracted acetic acid
along with some powdered calcium carbonate. Stu-
dents were able to observe the formation of product
calcium acetate. We concluded by discussing the ad-
vantages and disadvantages of both sodium chloride
and CMA as road salts. Students appeared unanimous
that reducing the cost of CMA was the most effective
way to achieve wide acceptance.

Session 11 *
"Focused" Microwave Applications
It is not often that you can bring together a strik-

ing example of both chemical and electrical engineer-
ing, but we did this in our session on "focused" micro-
wave applications. Specifically, we addressed the
problem of non-invasive cancer treatment, as well as
microwave sterilization. This topic was presented by
giving an overview of the technology, and following
up with a demonstration. The technology of cancer
treatment by microwaves centers on the fact that
cancer cells have high electrical conductivity and are
more sensitive to temperature increase than normal
tissue. Thus, techniques for focusing, or directing, the
microwaves enables heating of the cancer cells to the
point of cell death, without serious damage to adjacent
normal cells. We demonstrated this technique (using
a home microwave oven) by first showing that differ-
ent fluids (salt water, tap water, ethanol, salad oil,
aqueous solutions of the water soluble polymer poly-
vinylalcohol) have different electrical conductivities.
We then placed a small beaker of one fluid (saline,
modeling a tumor) in a larger flat tray containing
another fluid (salad oil, with much lower conductiv-
ity). We saw how the fluid in the beaker could be
elevated to a temperature substantially higher than
the one in the flat tray. We also explored how an air-
foamed material (whipped cream) absorbs micro-
waves, comparing that to beakers of selected fluids
placed in the foam.

Session 12 *
Organ Transplants
One of the leading researchers on immunosuppres-
sion for organ transplants gave an overview of this
topic, pointing out both the problems and the progress
in this area. We discussed the concepts of organ accep-
tance and rejection between donor and recipient. A
number of 35mm slides were used to illustrate, for
example, both healthy kidneys and those that had
been rejected. Because it is illegal to demonstrate
examples on live animals to high school students, we
could not illustrate the standard "skin patch" test.
However, we did take the students to the university
research operating room and showed them mice at
various stages of skin patch testing.

Session 13 *
Genetic Engineering and Production of Seaweeds
This session addressed the many uses of seaweeds
and the need for genetic engineering of new seaweed
strains. In addition to describing the objectives and
the methodology behind genetic engineering technol-
ogy in general, the global perspective of growing and
harvesting seaweeds (especially in developing coun-


tries) was presented. We demonstrated the "thicken-
ing" characteristics of agar and presented examples of
edible seaweed products. The session concluded with
a tour of the laboratory in which seaweeds are cul-
tured and grown.
Unfortunately, we did not survey the students be-
fore or after conducting our first pilot quarter. How-
ever, we did so for the second quarter. As noted
above, an application/questionnaire was given at the
initiation/conclusion of these sessions. Some overall
observations follow.
First, on the original application, only six students
indicated a serious interest in pursuing a career in
science or engineering (no one mentioned the word
"engineering"). On the concluding questionnaire, only
six students did not indicate the pursuit of science or
engineering as a career goal. Moreover, from their
responses on the final course evaluation form and on
the separate application form for a summer internship
program (completed by fifteen students), it appeared
that the students were more focused on technical in-
terests. While we cannot say if there was an earlier
unexpressed interest in the topical issues presented,
it is clear that these ninth (and some tenth) grade
students were sufficiently sophisticated to decide that
genetic engineering of seaweeds was exciting and that
investigating the use of biopolymers in concrete was
not exciting-or the reverse. Moreover, some stu-
dents expressed an interest in having demonstrations
and experiments with animals and in further pursuing
research on the topics we had discussed. (Note: Other
than showing an animal to the high school students,
demonstrating experiments by using live animals is
illegal in Massachusetts.)
At the conclusion of our second quarter pilot pro-
gram we devoted the last session to a buffet, followed
by the awarding of certificates. (An award was made
to students who missed three or fewer sessions.) Two
faculty members who had graduated from this school
spoke briefly, as did the dean of the college of en-
gineering. The students seemed to be pleased both
with the special awards session and with the opportu-
nity to complete a course evaluation form. In general,
throughout the pilot project we treated the students
as adults and found that they acted like adults.

Our future plans call for bringing together high
school science teachers and university professors to
plan the introduction of applications of modern
biotechnology into high school science courses. In our

first summer session, we anticipate that high school
science teachers will wish to learn more about modern
biotechnology, and especially its social applications.
Thus, a series of informal lectures and hands-on par-
ticipative demonstrations will be given by professors
who are well-established in selected areas of modern
biotechnology. Further, since the professors will need
to gain an understanding of what high school science
teachers believe is appropriate for presentation to high
school students, the high school teachers will present
informal seminars dealing with their experiences in
introducing the newer aspects of science and technol-
ogy into their courses.
Looking ahead, we also plan to initiate some of the
key recommendations from this summer study pro-
gram into a pilot program to be initiated during the
following academic year. This pilot program will in-
volve the introduction of key recommendations from
the summer study sessions into the high school class-
rooms and laboratories. We also anticipate that the
professors will give demonstrations and will involve
students in "show-and-tell" type experimental themes
coupled with measurement orientations (i.e., we wish
to integrate quantitation into all demonstrations).
Further, the pilot program will include regularly
scheduled monthly meetings with the professors and
the high school teachers in order to assess progress
and to discuss problems. [

REVIEW: Hazardous Waste
Continued from page 147

teaching and research, consulting, and governmental
experience to supplement his BS, MS, and PhD in
chemical engineering, and his MBA. Thus, he has real
design and management experience in waste treat-
ment technologies and has taught the material in the
classroom to engineering students. Moreover, he has
organized countless professional meetings dealing
with the HWM area for AIChE.

The text covers the entire field in 450 pages. It
begins with the basic definition of hazardous waste in
general terms and provides an historical background
for the field, both in the United States and Europe.
The latter is an important perspective because Euro-
pean concerns predate ours in many respects. Several
important case studies are provided to place the field
in its political context and to provide introductory
technical insight. Next, the process of risk assess-
ment is introduced with case studies. Then the author
provides two chapters which discuss the driving force
behind the HWM area: federal legislation.


The background begins with the Rivers and
Harbors Act of 1899 and includes explanatory pages
on the Atomic Energy Act, the National Environmental
Policy Act, the Occupational Safety and Health Act,
the Air Quality and Water Quality Acts, the Solid
Waste Disposal and Resource RecoveryActs, the Toxic
Substances Control Act (TSCA), the Resource Conser-
vation and Recovery Act (RCRA), the Comprehensive
Environmental Response, Compensation, and Liabili-
ties Act (CERCLA), and the Superfund Amendments
and Reauthorization Act (SARA) among others. The
final chapter of the introductory portion of the book
provides a detailed technical and legal definition of
hazardous waste.

The author then shifts to the technical side of the
field. First, he focuses on waste minimization, which is
perhaps the most important future concern in HWM.
This chapter treats the managerial portion of waste
minimization, including policy, benefits, priorities,
and tracking and auditing systems. This chapter does
not treat the engineering design aspects of waste
minimization, the heart ofwhich is chemical engineer-
ing, because the pedagogical aspects of this discipline
have not yet been developed and are rightfully the
subject of another book. Next, Wentz covers chemical,
physical, biological, and thermal treatment ofhazard-
ous waste in two excellent chapters which incorporate
both descriptive material and fundamental design
equations. Consistent with earlier portions of the text,
these chapters provide a legal standard context and
case studies.

In logical order, Wentz turns to the transporta-
tion of hazardous waste. Included are federal reg-
ulations, DOT and EPA procedures, definitions of
shippers and carriers, and the regulation of each.
Record-keeping, reporting, and manifesting are treated
with examples and the uniform manifest. State and
local regulations, with emphasis on notification, rout-
ing, emergency response procedures and equipment,
and right-to-know laws, are covered.

Finally, the text treats land disposal, ground-
water contamination, injection well disposal, process
siting and site remediation. Again, the author has
achieved comprehensive coverage ofhydrology, ground-
water chemistry, contamination, design ofmonitoring
wells, regulations, siting, and classification of wells,
with design equations and case studies. The Super-
fund law, the Hazard Ranking System (HRS), and
National Priority List (NPL), together with contain-
ment and treatment technologies and vitally impor-

tant financial strategies, play a role in the final chap-

Wentz has packed the text with important in-
formation needed by the practitioner, and he defi-
nitely achieves his stated goal in the preface "to in-
tegrate a broad field into a single book that deals with
all phases of this important subject." He provides
appendices of listed wastes and a surprising depth of
coverage despite the comprehensive nature of this
teaching text. The problems at the end ofeach chapter
could be more extensive, but are certainly at the right
level for the senior undergraduate or beginning gradu-
ate student for whom the text is intended. A solutions
manual is available.

This subject has and will continue to move
quickly, so much of the illustrative data in the early
chapters is already dated, but the need for this book
should warrant frequent updates. It is clearly a sur-
vey text, so that one should not expect in-depth
coverage of every topic; we continue to need other
texts, but Wentz has given us a start.

At Wayne state University, we offer several
dozen hazardous waste management courses as part
of our regular chemical and civil engineering degree
programs, but chemical engineering also administers
a Graduate Certificate Program [4] and a full MS in
Hazardous Waste Management [5,6]. Most schools
offering an extensive HWM program have a survey
course as the entry point [3]. For our introductory
course, we have adopted Wentz's Hazardous Waste
Management as the required text, but cannot cover
the text in a two-credit semester offering. One of the
highest compliments that I can pay to the text is that
our civil engineering faculty also use it for their
landfill course, which is well beyond the scope of our
introductory course.
1. Busch, P.L., "A Hazardous Waste Crises: Too Few People,"
Waste Age, September (1988)
2. Levine Associates, "Evaluating the Environmental Health
Workforce,"USDHHS Report 240-286-00076, January (1988)
3. Kummler, R.H., C.A. Witt, R.W. Powitz, and B. Stern, "A
Comprehensive Survey of Graduate Education in Hazardous
Waste Management," J. of the Air and Waste Management
Ass'n., 40, 32 (1990)
4. Powitz, R.W., J.H. McMicking, and R.H. Kummler, "A Gradu-
ate Certificate Program," J. Environ. Health, 52, 230 (1990)
5. Kummler, R.H., J.H. McMicking, and R.W. Powitz, "MS De-
gree in Hazardous Waste Management," ESD Tech., August
6. Kummler, R.H.,J.H. McMicking, and R.W. Powitz, "A Program
on Hazardous Waste Management," Chem. Eng. Ed., 23,222
(1989) 0


1B classroom



Part 3: Application

R. O. FOX, L. T. FAN
Kansas State University
Manhattan, KS 66506

IN THIS FINAL part of our three-part series on sto-
chastic modeling of chemical process systems, the
master equation derived in Part II is employed to model
a chemically-reacting system. The purpose is two-fold:
the first is to demonstrate the application of the master
equation, and the second is to show that fluctuations
will be negligible in a reacting system where the number
of discrete entities (molecules) is large. Nevertheless,
this is not always the case for a system with a relatively
small population, e.g., a bubbling fluidized-bed combus-
tor for large coal particles. Such a system also is not
uncommon at the outset and conclusion of any process;
these periods are the most critical from the standpoint
of operation, monitoring, and control.

For the reaction

B+XI X2+X3

its elementary steps can be expressed as

B+XI -- XX +X2

Xl+X2 X2,+X3

We shall assume that these reactions take place in a
well-mixed vessel of volume fl under isothermal condi-
tions. The proper modeling of concentration fluctuations
in the system requires knowledge of the elementary
(molecular) reaction mechanism. However, this informa-
tion is not known in many industrially relevant reac-
tions; thus, phenomenological kinetic models are em-
ployed [1]. Such phenomenological models, however, are
not sufficient to determine the exact nature of the inter-

Copyright ChE Division ASEE 1990

nal fluctuations.
We shall also assume that the feed stream to the
reactor contains only component Xi and that the system
has a mean residence time of Tr. Of the three compo-
nents involved in the reaction steps, X1 and X2 will be
variable, while B is assumed to be held at a constant
concentration. Finally, for deriving a stochastic model,
it will be assumed that each molecule behaves indepen-
dently and thus will react with a probability derivable
from the rate equations of chemical kinetics [2].

Rate of Transition Functions
If we define N1 and N2 as the numbers of molecules
of component X1 and X2, respectively, in the reaction
volume, the following rates of transition,
Wt(nl,n2g;A,k2), can be derived [2,3]:

Wt(n,,n2;1,0)= CfN (1)

W,(n,,n2;-1,0)= -+ -nln2 (2)

Wt (n,,n,;0,-1)=n- (3)

Wt(nl,n2;0,l)=Bkln, (4)

The first of these is due to the entrance of molecules
of X, into the reactor; hence, lCfNA/Ts is the number
of molecules of X, entering the reactor per unit time.
The second expression, Eq. (2), is due to molecules of
X, leaving the reactor and to the second chemical reac-
tion. The third, Eq. (3), corresponds to molecules of X2
leaving the reactor. Finally, the fourth expression cor-
responds to the first chemical reaction. Note that the k
is the second-order rate constant in terms of molecules
instead of moles with units of time (volume molecules).
The rate constant in terms of moles, k2, can be obtained
by multiplication of kg by the Avogadro number, NA.


Jump Moments
With the aid of Eqs. (9) and (11) in Part II, the jump
moments follow directly from Eqs. (1) through (4).
These are

1 CfNA 1n k
A, =2 nn2
T, -T Q

1 CfN, +n, knn

B,2 =B2,1 = 0

B22 n+Bkin1

The application of Eqs. (10) and (12) from Part II
followed by Eqs. (14) and (15) from Part II leads to the
coefficient matrices of the linearized Fokker-Planck
equation governing the fluctuations, i.e.,

A=[Aij]j= '

CfNA + + k2412
fB= p3ijI= 0

-k2 1


2 +Bkldl
t s

Average Value Equations
The zero-order terms in Eqs. (5) and (6) lead to the
following expressions for the average numbers of
molecules of the two components:

d (N,)= N N) k(N,)(N, (12)

(N2)=- (N) +Bk(NI) (13)
dt '

Dividing both sides of these expressions by ONA results
in the familiar rate equations for reactions in a well-
mixed reactor in terms of molar concentrations

d = (C -C,)-kC1C2 (14)
dt z,
C2 1 C +Bk C, (15)
dt Tg

In addition to the expressions for the average con-
centrations, the stochastic model also yields expressions

. the master equation is employed to model
a chemically-reacting system. The purpose is
two-fold: to demonstrate the application of the
master equation, and to show that fluctuations
will be negligible in a reacting system where the
number of discrete entities (molecules) is large.

(6) for the concentration fluctuations. The coefficient mat-
rices, Eqs. (10) and (11), are employed in conjunction
with Eq. (23) in Part II for this purpose.
When we divide both sides of the resultant expres-
sions by Ni, we obtain the following expressions in
terms of molar concentrations:

dVar[C]=-2 k2C2+ Var[C,]

-2kCCov[Ci,C,]+ +c+ +k2C,C2 (16)
(NA s 16)

S-Cov[C1,C2]= +k-C2 Cov[CC2
dt I
-k2CiVar[C2]+Bk1Var[CI] (17)

dVar[C2]=2BkCov[C,,C]-2 Var[C,]+ I C2+BkCI
dt N, RNA K

This set of coupled differential equations can be
solved for the covariance and variances of the fluctua-
tions. For our purposes, it suffices to note that the resul-
tant expressions will be proportional to (lNA)-'. Since
NA = 10?, we can safely conclude that unless f is very
small (=10-2), the concentration fluctuations will have
a standard deviation in the order of 10-12 mol/volume.
Such fluctuations, being imperceptible to most, if not
all, instruments commonly employed in practice, must
be considered negligible.

Correlation Functions
According to Eq. (25) in Part II, the expressions
for the auto- and cross-correlation functions are, re-

SKi,()= k- C+ + Ki,,(T)-k2C1K,2y(r),1 i=1,2 (19)

Ki,2(T)= Bk1Ki,1 ()- I-Ki,2(T), i=1,2 (20)

The initial conditions for these equations are the
steady-state covariances. Since these are proportional


to (fINA)-, so will be the correlation functions. The
real parts of the eigenvalues for the system of equa-
tions, Eqs. (19) and (20), are negative and, most im-
portant, functions of the macroscopic rate constants.
If the fluctuations were measurable, it would be possi-
ble to calculate the rate constants from steady-state
experiments. However, this is precluded in the chem-
ically-reacting system under consideration because of
the immeasurability of fluctuations due solely to the
stochastic combination of individual molecules.

We have seen that for a Markovian system, where
the rates of transition can be formulated, the master
equation can be solved approximately for the means
and correlation functions of the random variables of
interest. Thus it is possible to study the effects of
stochastic kinetics on the evolution of discrete popula-
tions and on the behavior of the system. This is impos-
sible to accomplish by the conventional deterministic
approach that leads to equations only for the means.
The master equation with the attendant System
Size Expansion offers advantages over other stochas-
tic formulations. For example, we have seen that the
well-known problem of coupling arises between mo-
ments of differing orders for a nonlinear system. In
most formulations this problem is circumvented by as-
suming independence among random variables or by
resorting to an ad hoc procedure. The System Size
Expansion follows a more rational pathway. Its power
series expansion retains a linear coupling between the
means and fluctuating components of the random vari-
ables-a coupling ignored or distorted when an ad hoc
approach is used. In a system where the System Size
Expansion is not applicable, the majority of the ad
hoc procedures are also invalid, and the system is best
handled by a simulation procedure, e.g., the Monte-
Carlo method.
The magnitude of internally-generated fluctuations
has been found to decrease as the number of independ-
ent entities increases. This, in turn, has led us to con-
clude that internal fluctuations due to molecular interac-
tions in a chemically-reacting system are negligible.
Nevertheless, it does not imply that the fluctuations in
a molecular system will be negligible in general. Indeed,
all systems are molecular, but fluctuations are often
present. Therefore, the key to modeling fluctuations is
the proper identification of their sources.
It is worth noting briefly that the auto- and cross-
correlation functions have characteristic time constants
which are functions of the macroscopic rate constants.

This observation should be of interest to the experimen-
talist wishing to determine the constants since the cor-
relation functions are measured for systems operating
at steady-state. It is known in physics as the fluctuation-
dissipation theorem and is used in measuring various
quantities, including diffusion coefficients.
In this series of articles we have concentrated on the
stochastic modeling of internal fluctuations in systems
amenable to a description involving a stochastic popula-
tion balance. Another important area of stochastic mod-
eling involving external fluctuations, i.e., fluctuations
generated by the environment of the system, is best
described by stochastic differential equations that have
not been discussed here. The reader will find details on
the formulation and solution of model equations for ex-
ternal noise systems in the monographs by van Kampen
[2], Gardiner [4], and Horsthemke and Lefever [5]. The
last gives an excellent introductory treatment of the
effects of multiplicative (noise terms appearing in the
governing equations multiplied by the dependent vari-
ables) and additive noise in single variable systems. It
is shown that additive noise does not change the steady-
state solution diagram in single variable systems (all
stable and unstable solutions exist at the same parame-
ter values), whereas multiplicative noise can lead to an
even richer steady-state solution diagram. New solution
branches are generated as the noise intensity increases.
Such behavior is known as a "noise induced transition"
to emphasize its dependency on the presence of external
multiplicative noise.
As remarked at the outset of this series, systems
with stochastic components are prevalent in chemical
engineering. Currently, several excellent treatises on
stochastic modeling stressing physical and chemical sys-
tems are available [2,4,5]. These sources are highly re-
commended to those wishing to expand their knowledge
of the subject. In addition, we feel that it is necessary
to obtain at least a rudimentary understanding of prob-
ability theory, random variables, and stochastic proces-
ses as presented in classical treatises such as Feller [6],
Karlin and Taylor [7], or, for the more mathematically
inclined, Gihman and Skorohod [8]. The reader in-
terested in stochastic differential equations will find an
understandable but rigorous presentation in the mono-
graph by Arnold [9]. The introduction of stochastic mod-
eling concepts into basic chemical engineering education
is an important step in furthering the ability of chemical
engineers to understand the complex systems they fre-
quently encounter. The wide availability of readable,
well-written material on stochastic modeling in the mod-
ern literature offers an excellent opportunity for chem-
ical engineers to incorporate new methods and fresh


ideas into the modeling of chemical process systems.


This material is mainly based upon work supported
under a National Science Foundation Graduate Fellow-
ship awarded to the first author.


Ai first jump moment
Ai,j coefficient in expansion of Ai
B concentration of component B
Bij second jump moment
Bij Bi,j /n
Cov [Ci, Cj] (CiCj)-(Ci)(Cj), cov ariance of Ci and Cj
Cf feed concentration of component X1
C1 concentration of component X1
C2 concentration of component X2
kl,k2 reaction rate constants
k reaction rate constant in units of molecules
Ki, (t) correlation matrix defined for Ci and Cj as

NA Avogadro number
Nj number of molecules of component j
expected value of random variable Ni
Wt({n)o,{n}l) rate of transition from state (n)o to state (n)l

Greek Letters
ti magnitude of change in random variable
', mean residence time
0i deterministic variable corresponding to
macroscopic behavior of Ni
n system volume


1. Villermaux, J., Genie de la Reaction Chimique: Conception et
Fonctionnement des Reacteurs, Technique et Documenta-
tion, Paris (1985)
2. van Kampen, N.G., Stochastic Processes in Physics and
Chemistry, North-Holland, New York (1981)
3. Fox, R.O., and L.T. Fan, "Application ofthe Master Equation
to the Bubble Population in a Bubbling Fluidized Bed,"
Chem. Eng. Sci., 42,1345-1358 (1986)
4. Gardiner, C.W., Handbook ofStochastic Methods, Springer,
New York (1983)
5. Horsthemke,W., andR. Lefever,Noise-Induced Transitions,
Springer, New York (1984)
6. Feller, W., An Introduction to Probability Theory and Its
Applications (2nd Ed.), Wiley, New York (1971)
7. Karlin, S., and H.M. Taylor, A First Course in Stochastic
Processes (2nd Ed.), Academic Press, New York (1975)
8. Gihman, I.I., and A.V. Skorohod, The Theory of Stochastic
Processes, Vols. I-II, Springer, New York (1974)
9. Arnold, L., Stochastic Differential Equations: Theory and
Applications, Wiley, New York (1974) O

REVIEW: Polymer Chemistry
Continued from page 153.
really descriptive since the authors seek to treat an
extremely large fraction of polymer science rather
than focussing on the narrower topic ofpolymer chem-
istry. It would be difficult to have included significant
computational problems in the present text because
the treatment is highly qualitative. Perhaps because
of my chemical engineering bias, some actual ex-
amples worked out in detail would have been attrac-
tive. For example, condensation and free radical po-
lymerization systems are important enough to merit
such treatment even in an overview book such as this.
The references given at the end of the chapters
are good, and, in fact, are some of the classics in the
various areas. Most of the references are rather old,
with only a sprinkling of new sources. While this is not
a particular problem for an introductory text, it cer-
tainly does not reflect the current literature in a way
needed for an introductory graduate (or even a more
advanced undergraduate) course.
While the light, easily-read approach is ideal for
many of the topics discussed in such an introductory
text, some topics might have benefitted from a de-
tailed treatment in order to give the student more
than a broad-brush appreciation of their importance
to the modern polymer field. It is likely that many
instructors would feel the need to supplement the
material in the areas of 1) polymer physical proper-
ties and their relationship to structure, 2) thermal
methods of analysis (DSC,TGA, etc.), and 3) reaction
kinetics for condensation and free radical systems.
Alternatively, of course, one could direct the student
to the original references given at the end of the
chapters to obtain sufficient detail to have a true
appreciation for these principles. If there is any topic
which comes close to being missed, it is the important
area ofpolymer-solvent and polymer-polymer thermo-
dynamics. Although the topic of solubility of polymers
in solvents is mentioned, the treatment and impor-
tance of solution thermodynamics is given practically
no coverage.
The authors indicate that the book could be
covered in a normal semester or in two quarter peri-
ods, and this seems reasonable. Even with supple-
mental information and exercises given in the areas
noted above, the easily-read style and frequent use of
drawings make the material easy to read and to
understand. Even if some of the more technological
topics covered in the last 40% of the book are not
discussed in class, they make useful reading for a
student seeking an overview of the field. C





A Laboratory Experiment

University of Colorado
Boulder, CO 80309-0424

OVER THE LAST FOUR YEARS, we have offered a
hands-on laboratory course in biotechnology [1]
which accompanies a lecture course on "Recent Ad-
vances in Biotechnology" for chemical engineering
seniors and entering graduate students. Of the seven
experiments normally conducted in this course, an ex-
periment on plasmid instability in recombinant cul-
tures pertains most directly to the modern biochemi-
cal engineering principles and the recent advances in
biotechnology discussed in the lecture course.
Further, the experiment is the most recently de-
veloped and will probably be more difficult to repro-
duce in other chemical engineering laboratories. It is
our objective here to discuss the important theoretical
and practical aspects in more detail so that this novel
experiment may be more easily duplicated in other
undergraduate laboratory courses.
Recombinant bacterial cultures are inherently un-
stable. Bacterial cells which harbor recombinant plas-
mids are commonly at a disadvantage when competing
with plasmid-free cells for essential nutrients. Since
the synthesis of a recombinant product depends en-
tirely on the stable maintenance of the plasmid-bear-
ing strain, a great body of research has dealt with the
mechanisms of plasmid instability. Many methods are
being pursued to genetically eliminate plasmid insta-
bility [2]. One technique, completely successful at the
laboratory level and employed in this experiment, is
to use selective media with an antibiotic resistance
marker on the plasmid vector. Two dominating factors
have been most often linked to the observed culture
instabilities: plasmid segregation and a "growth-rate

*Current Address: Department of Chemical and Nuclear Engineer-
ing, University of Maryland, College Park, MD.

differential" between plasmid-bearing and plasmid-
free cells. Plasmid segregation is a result of uneven
plasmid partitioning from the mother to daughter cells
upon cell division and therefore generates plasmid-
free from plasmid-bearing cells. The growth rate dif-
ferential is due to the redirection of cellular catabolic
and anabolic activity in the recombinant cells while
they synthesize the desired product. Consequently,
plasmid-bearing cells do not have full use of their own
resources and grow more slowly than those which are
plasmid-free. The plasmid-free cells born by plasmid
segregation are thus able to rapidly overtake the over-
all population.
This laboratory experiment is intended to
familiarize the student with microbiological tech-
niques as well as the analysis of exponential growth
in bioreactors. Further, students are introduced to
the experimental and theoretical characterization of
instabilities observed with recombinant bacteria as

William E. Bentley is presently an assistant profes-
sor of chemical engineering at the University of
Maryland and an assistant staff scientist at the
Maryland Biotechnology Institute. He received his
BS (1982) and his MEng (1983) from Cornell Univer-
sity, and his PhD (1989) from the University of
Colorado. His research interests are in the produc-
tion of heterologousproteins from recombinantmicro-
S- i organisms.

Dhinakar S. Kompala is an assistant professor of
chemical engineering at the University of Colorado.
He received his BTech (1979) from the Indian Insti-
tute of Technology, Madras, and his MS (1982) and
his PhD (1984) from Purdue University. His current
research interests are in fermentation of recombi-
nant bacterial, mycelial and hybridoma cells, and in
affinity separations of proteins and cells.

Copyright ChE Division ASEE 1990


The laboratory is designed so that the students are exposed to problem solving methods both as
individuals and as participants of a group. The handout is not a "cookbook" step-by-step account of
the lab procedure-such labs often lack meaningful educational value because they preclude active
student participation. Instead, the instructor should create an environment
containing appropriate tools without dictating the precise methods.

noted above. The laboratory is designed so that the
students are exposed to problem solving methods both
as individuals and as participants in a group. The stu-
dent lab handout (available from the authors) is not a
"cookbook" step-by-step account of the lab proce-
dure-such labs often lack meaningful educational
value because they preclude active student participa-
tion. Instead, the instructor should create an environ-
ment containing the appropriate tools without dictat-
ing the precise methods.
The pre-lab discussion emphasizes the theoretical
background and analysis in addition to the laboratory
techniques. Demonstrations for sterile serial dilu-
tions, plating, and optical density measurements are
given. Typically, the laboratory is divided into groups
of three or four students, while the written reports
are prepared on an individual basis. In this way, group
efforts are emphasized but each student is ultimately
responsible for his/her own work.

The pioneering theoretical work was a simple
model which could be employed to predict the popula-
tion dynamics of a mixed-population batch culture dur-
ing exponential growth [3]. This work is summarized
below. The growth of the plasmid-bearing, P, and
plasmid-free, N, subpopulations can be described

d =(1-p)1+P (1)

= pR+P+ -N (2)
where t is time (hr), p is the segregation coefficient
dimensionlesss), p is specific growth rate (hr-1), and
superscripts + and are cells with and without plas-
mid, respectively. By setting

P=P,, N=N, at t=0 (3)

from Eq. (1) and (3), we obtain

p poe(1-p)P t (4)
and from Eq. (2), (3) and (4), we obtain

N=N. e.'+ PR+Po e(l-P)+t_ e (5)
(1- p)p l-

Limiting Cases for Graphical Analysis of Eq. 7

Case Dominant Factor

I growth rate differential
II growth rate differential
III plasmid segregation
IV plasmid segregation

Initial Condition

No >0
No 0
No > 0
No= 0

The fraction of plasmid-bearing cells can then be writ-
ten as

P Po e('-P)' t
P+N Poe,(1_P)t + Neoe-t + PPo [e(- p)jpt- e-t
0(- p) -

We have linearized this expression for easier graphical
analysis of laboratory data

in +A-1 =In A+ --p) (7)

Eq. (7) can be applied to four separate cases so that
a slope and intercept can be obtained from the data
yielding an important experimental parameter which
characterizes the culture dynamics of any experimen-
tal plasmid/host system (see Table 1).
The culture instability for our experimental sys-
tem is dominated by the growth rate differential since
the plasmid exists at a high copy number (low segre-
gation probability). Therefore, we simplify Eq. (7) for
our experiment (Case I). If [+p < J- p+, then

A P< 1

In F 1) = (N + ( -)t (8)

so that the difference in growth rate between the plas-
mid-bearing and plasmid-free cells is the slope of this
linear relationship.


Materials and Methods

A. Culture Conditions

E. coli RR1, obtained from Bethesda Research
Laboratories (BRL), was transformed with the plas-
mid pBR329 (which infers resistance to tetracycline,
ampicillin, and chloramphenicol) also from BRL (ac-
cording to Maniatis, et al. [4]). E. coli RR1 is used as
the host bacterium because of its high transformation
efficiency. pBR329 is a model plasmid which exists at
high copy numbers, but could easily be replaced by
any ColEl-type plasmid. Experiments were per-
formed in shake flasks controlled at 37C in a water
bath shaker (New Brunswick Scientific Model RW-
650). Media (M9-a minimal media) was prepared ac-
cording to Maniatis, et al. [4]. The host bacterium re-
quires supplemental leucine, proline, and vitamin B1
in defined media. These were added at levels of 41,
164, and 0.166 IJg/ml respectively (Fisher Scientific).
Bacterial cultures, grown overnight, in the presence
of antibiotic (tetracycline, 12 [g/ml), were diluted
( 1/20 dilution) and grown again for approximately
one hour in several flasks containing media identical
to that used in the subsequent experiments. In this
way, we were assured that each inoculum was in the
exponential growth phase at conditions identical to
those of the experiments and hence, preculture
metabolic variation was eliminated. Each inoculum
was approximately 1 ml for every 100 ml of culture

B. Growth Rate Measurements

Optical density absorbancee at 600 nm) was meas-
ured in the linear range (0.05 to 0.25 OD units) on a
Beckman DU-50 Spectrophotometer. More dense
samples were diluted with sterile water to obtain OD
in the linear range. The OD was corrected for the
background absorbances of the differing sterile media.

C. Fraction Plasmid-bearing Cells, F

The fraction of plasmid-bearing cells was deter-
mined by replica painting. Samples were diluted in
sterile water until 40 jl contained approximately 100
to 300 cells. This quantity was spread on an LB agar
plate and incubated overnight. Sterile felt was used
to transfer the colonies from the original LB plate to
one plate each of LB and LB with tetracycline (12
pg/ml). The number of colonies on the LBtet plate
divided by the number on the second LB plate is the
fraction recombinant cells. Frequently, replica plating
was performed on LBamp plates in addition to LBtet
in order to confirm the plasmid structural stability.

Additional Precautions

Extra care must be taken to ensure the quality of
data so that statistical analysis can be performed on
the results. We conduct the growth experiments in a
modified minimal medium (M9, Maniatis, et al. [4]) so
that the growth-rate curve is linear for at least five
hours. Rich media should be avoided since the growth
rate continually decreases as some nutrients become
depleted. Three flasks are prepared: (1) E. coli RR1
(no plasmid), (2) E. coli RR1 with pBR329 (100% plas-
mid-bearing), and (3) a mixed culture of the previous
two. A detailed, step-by-step procedure is available
from the authors. However, a few more subtle points

It is advantageous to start the mixed culture (flask
3) at F = 0.9 or at F = 0.4, since the standard
deviation in replicate plating is nNP where n is

I -'

t5 A PI(N+P)
as -1.5

0 / E. coli RR1
S2 +* Mixed cunure
-2.5 V E. col RRI IpBR3291

11 13 15 17 19 21
Time of Day (hour)

FIGURE 1. Growth in shake flasks (a first attempt).


0 082 *
06 I

-2 04

S 10 12 14 16 18 20 22 24

V' E.Col RRi[pBR329]

Time of Day (hour)
FIGURE 2. Optical density versus time for three cultures:
plasmid-free, mixed, and plasmid-bearing. F is also in-
cluded from the mixed culture.


the number of colonies transferred [5] and is highest
around 50% plasmid-bearing.

The plasmid-bearing cells (grown overnight in media
containing antibiotics) must be washed in sterile
media containing no antibiotic before inoculating
the experiments. This ensures that (1) no antibiotic
is transferred to the mixed culture flask which
could kill the plasmid-free cells (see Figure 1), and
(2) the plasmid-bearing population will be free to
segregate so that '1 calculated from OD
measurements in this flask is accurately ascribed
to the plasmid-bearing cells (F should be measured
in this flask as well).

The washed cells should be equilibrated in 1 ml
sterile media for one hour at 37C before
inoculating the experiments so that the cells are

I .
0.9 N
S 0.5
S0.3 E Regression
0 Mixed Culture
0 1 3 5 7 9 1 13
Time (hours)
FIGURE 3. In (1/F-1) versus time. This is the reduced
form of Eq. (7) for Cases I and II. The slope of this line
is (A. Jp).

0 -U


O -2 Predicted Growth

Mixed Culture Data

43 *
8 10 12 14 16 18 20 22 24
Time of Day (hour)
FIGURE 4. Optical density versus time. Predicted values
are based on + (plasmid-bearing culture) and the re-
sults from Figure 3.

exponentially growing upon inoculation in the
experiment flasks and smooth data are obtained
from the start (see Figure 1 vs. Figure 2).

SAlthough it may seem cumbersome, take data
frequently (approximately every twenty minutes
for OD and every forty minutes for F) so that
statistical significance can be established.


Figure 1 is an example of a first attempt at this
experiment. None of the above mentioned points were
performed, and consequently this experiment was of
no value. Note that the mixed culture F actually in-
creased with time (the plasmid-free cells were killed
by residual antibiotic).
The experiment illustrated in Figure 2 was suc-
cessful. The growth rates of the cultures are listed in
Table 2.
In Figure 3, In(1/F 1) is plotted versus t. The
slope, (pL +), was 0.114 hr1 and 95% confidence
limits were + 0.024 hr-1. The measured difference was
0.094 hr-1 (0.511-0.417) which is within the 95% confi-
dence limits of (L- p- ) found from the plot in Figure
3. It is important to note that the value of p is there-
fore not significantly different than zero. The meas-
ured F from the E. coli RR1 [pBR329] culture was
always unity which also demonstrates that p 0. The
growth of the mixed culture can be predicted from the
growth rates of the other two flasks and the initial OD
(Po and No). The predicted growth of the mixed cul-
ture and the actual data are shown in Figure 4. Excel-
lent agreement between the experiment and predic-
tions is obtained during the exponential phase, for
which the model equations are appropriate.
A different experimental host/vector system (with
low copy number and small growth rate differential,
so that I+ p > RJ- ip., Cases III and IV) can lead
to an indirect measurement of the plasmid copy
number, Np. The data (F) are plotted using a slightly

Specific Growth Rates and 95% Confidence Limits for
the Three Shake Flask Cultures


E. ColiRR1
Mixed Culture
E. coliRR1 [pBR329]

9 95% limits
hr' on g




different simplification of Eq. (7):

In = In 1 J+ N + ( p)t (9)

where the slope yields p. Np can then be calculated
using the following results from Seo and Bailey [6]

p=lIn (2 ) and = 21-NP (10)
In (2)
The experimental measurement for Np is quite labor

This lab can provide an introduction to micro-
biological techniques, mathematical modeling, and
statistical methods while studying a problem of cur-
rent importance in biotechnology. As previously men-
tioned, two handouts are available from the authors:
one describes the mathematical and experimental pro-
cedures in detail, and the other is the pre-lab handout
for the students. Over the past three years, this labor-
atory has evolved into the present form and continues
to be enhanced from the student input which is re-
quested in their written reports.

1. Davis, R.H., and D.S. Kompala, "Biotechnology Laboratory
Methods, Chem. Eng. Ed., 23,182 (1989)
2. Imanaka, T.,Ann. N.Y.A.S., 506,212 (1987)
3. Imanaka, T., and S. Aiba, Ann. N.Y.A.S., 369,1 (1980)
4. Maniatis, T., E.F. Fritsch, and J. Sambrook, Molecular
Cloning: A Laboratory Manual, Cold Spring Harbor, NY
5. Caulcott, C.A., A. Dunn, H.A. Robertson, N.S. Cooper, M.E.
Brown, and P.M. Rhodes, J. Gen Micro., 133, 1881 (1987)
6. Seo, J., and J.E. Bailey, Biotech. Bioeng., 27,1668(1985) 1-

REVIEW: Physical Polymer Science
Continued from page 135.
American Chemical Society has taken action. The
ACS Committee on Professional Training has issued
guidelines for "approved degree programs" [Chem. &
Eng. News, p 49, May 1, 1989]. In addition to a core
curriculum of elementary, organic, and physical chem-
istry, the approved program in chemistry/polymers
calls for two semesters of polymer science (physical
and organic), laboratory work, and an advanced course.
Sperling has written a textbook which fits the
ACS criterion admirably. In general, the topics cov-
ered are those suggested for a course in Physical
Chemistry of Polymers in a syllabus issued by the
Joint Polymer Education Committee of the ACS
(Polymer Education Newsletter, Spring, 1989). Since

the book presupposes no previous knowledge of poly-
mers beyond the usual undergraduate organic and
physical chemistry courses, the first chapter is a brief
introduction on polymerization which mainly serves
to supply a vocabulary of basic polymer terminology.
In the first third of the book, a chapter on chain
structure and configuration includes discussion of
some methods of characterization. This is followed by
chapters describing concepts of molecular weight as
well as solution and phase behavior.
The remainder of the book emphasizes proper-
ties of bulk polymers. This includes chapters on crys-
tallinity, classes, and rubber elasticity. Viscoelasticity
and mechanical behavior (failure tests) complete the
The ACS Syllabus for a course in Physical Chem-
istry of Polymers is rather broad and includes some
topics not covered in Sperling's book. Many chemical
engineers would probably have been exposed to rhe-
ology in other courses so the omission of non-Newto-
nian flow (at the level of the power-law and the Ellis
model, for example) can be overlooked. The ACS
syllabus also suggests topics in polymer processing
(molding, extrusion, etc.) which are beyond the scope
of the present book.
In this day when most polymer books tend to be
collections of papers presented at meetings, a text-
book with a single author is something of a novelty.
The unified viewpoint and consistency oftreatment in
this book should make it very convenient to use as a
text. Each chapter concludes with a "Homework"
section containing both numerical and essay-type
questions which are useful for self-study or as class
assignments. In addition to the many specific refer-
ences in each chapter, there are suggestions for gen-
eral reading, most of which are authored (rather than
edited) books. The language of the text is quite easily
understood and the general organization is neat and
In addition to the chemistry/polymers topic, ap-
proved curricula in specialty areas of chemistry/bio-
chemistry and chemistry/education also have been
adopted by ACS. It is noteworthy that in commenting
on the usefulness of these new options, M.J. Caserio
of the ACS Professional Training Committee is quoted
as saying, "...90% of the graduates in chemistry who
enter the job market will find themselves working in
some area dealing with macromolecules." Those of us
who labor in the polymer vineyards of chemical engi-
neering have been saying the same thing about our
graduates for many years. This book is a welcome
addition to the expository literature for teachers and
students in the field of macromolecules. 7



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