Chemical Engineering

novel research project combining the technologies of cell biology, electronic circuit fabrication and nanostructured substrates could eventually lead to advances in tissue engineering that allow researchers to grow replacement parts for the human body.

By combining their expertise, Materials Research Science and Engineering Center (MRSEC) researchers are developing new materials and fabrication methods leading to nanostructured surfaces that can be integrated into biological systems to direct and modulate the behavior of cells.

Assistant Professor Paul Nealey, Associate Professor of Electrical and Computer Engineering Amy Wendt and Professor of Ophthalmology Christopher Murphy are building 1-to-100nm-scale silicon scaffolds on which to grow corneal epithelial cells. These three-dimensional scaffolds mimic the topography of natural basement membranes upon which these cells grow in the human body. The team has preliminary evidence that the topography of the scaffold influences the direction and behavior of the cells. Until recently, most research in this area focused on the influence of surface chemistry alone.

This fundamental research is of great significance to tissue engineering in general. The lessons learned from corneal epithelial cells will likely be applied to cells throughout the body.

The effort involves experts from across the Madison campus, including post-doctoral researchers George Abrams and Xiaomin Yang, PhD student Ana Teixeira, research specialist Sean Campbell, and Ralph Albrecht, an expert in high-resolution imaging of surfaces and cells. Future studies will include Medical School Professor Paul Bertics, who will supervise investigations addressing intracellular signaling pathways involved in translating a bio-mechanical stimulus delivered at the cell membrane. (Top row, from left: Campbell, Murphy, Bertics, Nealey. Front row, from left: Abrams, Teixeira.)

Research to improve catalytic systems

Many reactions that industrial chemists would like to perform occur too slowly to be economically feasible, or are accompanied by side reactions that yield undesirable byproducts. Catalysts have been found for many reactions that activate molecular reactants, forming reactive intermediate compounds and transitional structures that guide the reaction down a particular path.

Professor Jim Dumesic and his research group are developing a better understanding of the fundamental mechanisms driving these catalytic processes and they are using these results to design new or improved catalytic systems. For example, Dumesic and chemical engineering researcher Randy Cortright recently patented a platinum/tin alloy catalyst that allows the selective conversion of isobutane to isobutylene, a chemical intermediate that can be used to produce higher-octane gasoline. Through a variety of microcalorimetric and spectroscopic studies, combined with quantum chemical calculations performed in collaboration with researchers at the Danish Technical University, Dumesic's group was able to show that tin exerts a strong electronic effect on platinum, altering the relative bond strengths of various species on the alloy surface. As a result, the alloy catalyst suppresses side reactions seen with platinum catalysts and prevents deactivation of the catalyst caused by accumulation of hydrocarbon residues.

Designing better control of chemical processes

New products in the chemical industry, especially high-value-added compounds such as pharmaceuticals, are increasingly complicated in chemical structure. Often a compound will exhibit multiple structures, only one of which may have the desired properties.

When producing or purifying such compounds, small, localized or transient variations in such factors as temperature, pressure, concentration of reactants, or the presence of impurities, which may be difficult or impossible to monitor in real time, may tip the balance from one form to another.

Working with a compound that exhibits two crystalline structures, Professor Jim Rawlings and PhD student Daniel Patience are exploring the use of in situ video microscopy and image analysis to provide instantaneous feedback on distributions of crystal size and shape in a batch crystallizer. They are developing models of the crystallization process that will use this information to allow real-time control of the process conditions affecting crystal morphology. Rawlings has established the Texas-Wisconsin Modeling and Control Consortium to promote collaborations with industry on this and other projects aimed at improving product quality, increasing efficiency and reducing waste through improved control of a wide variety of chemical processes.

James B. Rawlings, Chair
2014 Engineering Hall
1415 Engineering Drive
Madison, WI 53706-1691

Tel: 608/262-1092
Fax: 608/262-5434
E-mail: che@che.wisc.edu
www.engr.wisc.edu/che