The 20th Annual Biochemical Engineering Symposium was held at Kansas State University on April 21,1990. The objectives of the symposium were to provide: (i) a forum for informal discussion of biochemical engineering research being conducted at the participating institutions and (ii) an opportunity for students to present and publish their work.

Twenty-eight papers presented at the symposium are included in this proceedings. Some of the papers describe the progress of ongoing projects, and others contain the results of completed projects. Only brief summaries are given of the papers that will be published in full elsewhere. The program of the symposium and a list of the participants are included in the proceedings.

Contents
Cell Separations and Recycle Using an Inclined Settler, Ching-Yuan Lee, Robert H. Davis and Robert A. Sclafani

Micromixing and Metabolism in Bioreactors: Characterization of a 14 L Fermenter, K.S. Wenger and E.H. Dunlop

Production, Purification, and Hydrolysis Kinetics of Wild-Type and Mutant Glucoamylases from Aspergillus Awamori, Ufuk Bakir, Paul D. Oates, Hsiu-Mei Chen and Peter J. Reilly

Dynamic Modeling of the Immune System, Barry Vant-Hull and Dhinakar S. Kompala

Dynamic Modeling of Active Transport Across a Biological Cell: A Stochastic Approach, B.C. Shen, S.T. Chou, Y.Y. Chiu and L.T. Fan

Electrokinetic Isolation of Bacterial Vesicles and Ribosomes, Debra T.L. Hawker, Robert H. Davis, Paul W. Todd, and Robert Lawson

Application of Dynamic Programming for Fermentative Ethanol Production by Zymomonas mobilis, Sheyla L. Rivera and M. Nazmul Karim

Biodegradation of PCP by Pseudomonas cepacia, R. Rayavarapu, S.K. Banerji, and R.K. Bajpai

Modeling the Bioremediation of Contaminated Soil Aggregates: a Phenomenological Approach, S. Dhawan, L.E. Erickson and L.T. Fan

Biospecific Adsorption of Glucoamylase-I from Aspergillus niger on Raw Starch, Bipin K. Dalmia and Zivko L. Nikolov

Overexpression in Recombinant Mammalian Cells: Effect on Growth Rate and Genetic Instability, Jeffrey A. Kern and Dhinakar S. Kompala

Structured Mathematical Modeling of Xylose Fermentation, A.K. Hilaly, M.N. Karim, I. C. Linden and S. Lastick

A New Culture Medium for Carbon-limited Growth of Bacillus thuringiensis, W. -M. Liu and R.K. Bajpai

Determination of Sugars and Sugar Alcohols by High Performance Ion Chromatography, T. J. Paskach, H.-P. Lieker, P.J. Reilly, and K. Thielecke

Characterization of Poly-Asp Tailed B-Galactosidase, M.Q. Niederauer, C.E. Glatz, l.A. Suominen, C.F. Ford, and M.A. Rougvie

Computation of Conformations and Energies of cr-Glucosyl Disaccharides, Jing Zepg, Michael K. Dowd, and Peter J. Reilly

Pentachlorophenol Interactions with Soil, Shein-Ming Wei, Shankha K. Banerji, and Rakesh K. Bajpai

Oxygen Transfer to Viscous Liquid Media in Three-Phase Fluidized Beds of Floating Bubble Freakers, Y. Kang, L.T. Fan, B.T. Min and S.D. Kim

Studies on the Invitro Development of Chick Embryo, A. Venkatraman and T. Panda

The Evolution of a Silicone Based Phase-Separated Gravity-Independent Bioreactor, Peter E. Villeneuve and Eric H. Dunlop

Biodegradation of Diethyl Phthalate, Guorong Zhang, Kenneth F. Reardon and Vincent G. Murphy

Microcosm Treatability of Soil Contaminated with Petroleum Hydrocarbons, P. Tuitemwong, S. Dhawan, B.M. Sly, L.E. Erickson and J.R. Schlup