Chemical Engineering @ChemengFiles.Com

For aerosol Brownian coagulation in the transition regime of Knudsen number in the presence of an interparticle potential, the Fokker-Planck equation is solved by using the Grad's 13-moment method. The mass and energy accommodation coefficients that are used to describe the results of collisional processes are appropriately defined and interfaced with the Fokker-Planck moment equations. Analytical and numerical solutions of the number and energy flux profiles for the potential-free, power-law potential, van der Waals potential, and Coulombic potential situations are obtained. The results are in good agreement with those predicted by the flux-matching method of Fuchs. The present fundamental approach, therefore, provides theoretical support of the coagulation coefficient expression obtained by the empirical flux-matching method.

Cellectricon announced the signing of a cooperation agreement with The Automation Partnership (TAP) in the UK, manufacturers of advanced automated systems for cell culture, treatment, and sample applications for exploration of high performance. Under the agreement, TAP will jointly develop and manufacture the system Dynaflow (R) HT, the platform for exploration of ion channel and high-performance next generation of Cellectricon. Dynaflow (R) HT will be launched and
marketed in 2009. Advertisement

The objective of my work was to prepare heterogeneous catalysts that can perform cooperative catalysis. Cooperative catalysis occurs when the presence of two or more functional groups provide an acceleration of a chemical reaction beyond what is possible when either of the two species is used independently. New catalytic materials were synthesized by functionalizing mesoporous silica (SBA-15) with two different functional groups with the groups distributed either randomly or arranged into heterodimeric pairs. The dependence of catalytic activity and selectivity on the surface arrangement (random vs. paired, distance between paired species) was investigated for several different condensation reactions.

Catalysts featuring both sulfonic acid and thiol groups were investigated for the synthesis of various bisphenols. Paired alkylsulfonic acid/thiol catalysts outperformed randomly-distributed catalysts in the synthesis of bisphenol A and bisphenol Z. The distance between the two groups in the acid/thiol pair was varied and the activity and selectivity were found to diminish rapidly as the acid/thiol distance grows. Paired arylsulfonic acid/thiol catalysts outperformed randomly-distributed catalysts in the synthesis of bisphenol Z, whereas the synthesis of bisphenol A was insensitive to spatial arrangement.