John A. Quinn

Professor Emeritus
Chemical and Biomolecular Engineering

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Honors and Awards:
Allan P. Colburn Award - American Institute of Chemical Engineers – 1966, S. Reid Warren - Jr. Award for Distinguished Teaching - University of Pennsylvania – 1974, National Academy of Engineering – 1978, Robert D. Bent Professorship - University of Pennsylvania – 1978, Alpha Chi Sigma Award - American Institute of Chemical Engineers – 1978, Sixth Mason Lecturer - Stanford University – 1981, Organization of American States Lecturer - Argentina – 1981, M. Van Winkle Lecturer - University of Texas – 1983, D.L. Katz Lectureship - University of Michigan – 1985, Sherman Fairchild Distinguished Scholar - California Institute of Technology – 1985, Irish-American Technology Exchange Programme Lecturer - University College Dublin – 1986, Reilly Lectureship - University of Notre Dame – 1987, John C. and Florence W. Holtz Lecturer - Johns Hopkins University – 1991, American Academy of Arts and Sciences – 1992, Merck Distinguished Lecturer - Rutgers University – 1993, Alan S. Michaels Lectureship in Biological and Biomedical Engineering - Massachusetts Institute of Technology - Inaugural Symposium – 1995, Distinguished Research Lecturer in Chemical Engineering - Carnegie Mellon University - 1997

Research Expertise:
Membrane Science and Engineering
We are exploring a number of phenomena related to the fabrication, characterization and use of engineered membranes in chemical processing, especially bioprocesses. Recent studies have included membrane reactors that couple chemical conversion and permselectivity to accomplish separation and enrichment in a single composite structure. We are using monolayer assembly techniques to prepare ultrathin membranes; we propose to incorporate functional components into these structures to facilitate specific transport properties. With recent advances in untrathin-film technology, it is possible to engineer - at the molecular level - films with different architecture - both in composition and in spatial arrangement or order - and associated permeation properties. In particular, we hope to show how transport across these layers is governed by molecular orientation: the geometry and stacking of molecular layers and the population and placement of well-defined "holes" or defects within the film. These latter studies (joint with Professor Vanderlick) are conducted using Langmuir-Blodgett deposition methods.

Cell Adhesion and Surface Motility
Problems of cell adhesion and motility are central to the manipulation and separation of particular cell types. We are studying cell adhesion using a radial flow detachment assay in which we examine the adherence of various cell types to ligand-coated surfaces; our aim is to identify and analyze the controlling parameters such as receptor/ligand densities and their equilibrium and dynamic interactions. Our motility studies involve the migration of large vessel endothelial cells over uniform and nonuniform surfaces - a form of haptotaxis. Here, too, we are attempting to make fundamental observations under known conditions which will contribute to our understanding of cell locomotion on surfaces. Ongoing studies include the attachment of bacteria to immobilized species-or-strain-specific antibodies fixed on the surface of the radial flow chamber. We are studying strains of E. coli [joint with Professor H. Goldfine, Department of Microbiology] that express Type 1 pili (fimbriae) that bind to fibronectin and whose adhesion is inhibited by mannose and its derivatives; we hope to use our assay to provide a quantitative measure of the relative effectiveness of adhesion blocking agents.

Transport Behavior of Motile Bacteria
Here we are examining the random and directed (chemotaxis) motility of bacteria at both the macroscopic (population) and microscopic (single cell) level. We hope to devise simple, reliable methods of measuring motility coefficients and chemotactic parameters to interpret the behavior of bacteria in various environments with possible applications to bioremediation as well as environmental studies. At this time we are investigating the movement of bacteria in confined geometries - channels in which the size of the bacteria and channel are comparable. Using techniques of videomicroscopy, microfabrication and image analysis, we have made measurements of interaction between the swimming bacteria and the confining walls. Based on this information we are developing computer models which simulate the observed behavior of the motile bacteria.

Education:
B.S., Chemical Engineering, University of Illinois, 1954
Ph.D., Chemical Engineering, Princeton University, 1959

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