He holds a B.S. degree in Chemistry from Boston College and a Ph.D. degree in Chemistry from Notre Dame. Dr. Callen is a member of ACS, ASMS, and Sigma XL His primary research interests have been centered on the development of gas and liquid chromatographic techniques for the analysis of hydrocarbon process streams. Charles A. Simpson is a senior research chemist in the Composition and Structure Research Group. He received his Ph.D. degree in Analytical and Physical Chemistry from the University of Delaware in 1958. His primary research activities are the identification and analysis of complex mixtures, including petroleum residua and related substances. Dr. Simpson is a member of ACS.Joseph G. Bendoraitis is a research associate in the Composition and Structure Research Group. His current interests lie in the development of procedures for the analysis of petroleum and coal-derived materials using mass spectrometry, nuclear resonance, and gas chromatography. He holds a B.S. degree in Chemistry from Wilkes College, an M.S. degree in Chemistry from Lehigh University, and a Ph.D. in Chemistry from Temple University. Dr. Bendoraitis is a member of ACS, ASMS, ASTM, and Sigma XL He has numerous publications in the areas of petroleum analysis, petroleum geochemistry, and radiolysis of hydrocarbons.Sterling E. Voltz is a research associate in the Process Research and Development Section. He is currently working on processes for synthetic fuels. His past industrial experience includes positions at General Electric, Sun Oil, and Houdry Process. Dr. Voltz obtained a Ph.D. in Physical Chemistry from Temple University and he also did graduate work at the University of Pennsylvania. He has numerous patents and publications in catalysis, surface chemistry, kinetics, petroleum and petrochemical processing, synthetic fuels, and automotive emission control. He is a member of ACS, Catalysis Society and Sigma Xi.