We have used self-assembled monolayers (SAMs) prepared from omega-terminated alkanethiols on gold to generate model surfaces and examine the effect of surface composition on the adsorption of Photosystem I (PSI), stabilized in aqueous solution by Triton X-100. Triton-stabilized PSI adsorbs to high-energy surfaces prepared from HO- and HO2C-terminated alkanethiols but does not adsorb to low-energy surfaces. The inhibition of PSI adsorption at low-energy surfaces is consistent with the presence of a layer of Triton X-100 that adsorbs atop the hydrophobic SAM and presents a protein-resistant poly(ethylene glycol) (PEG) surface. While the presence of the PEG surface prevents the adsorption of PSI, the displacement of the inhibiting layer of Triton X-100 by dodecanol, a more active surfactant, greatly enhances the adsorption of PSI. This inhibiting effect by Triton X-100 can be extended to other protein systems such as bovine serum albumin.

Kinetic studies were made in a differential flow reactor of the hydrogenation of a-methylstyrene with the liquid trickling over a bed of catalyst pellets countercurrent to a stream of hydrogen. The catalysts consisted of palladium, platinum, rhodium, ruthenium, and nickel supported on the external surfaces of alumina pellets.With palladium at pressures above 3 atm. the apparent rate-controlling step was a surface reaction between dissociated hydrogen and a-methylstyrene both adsorbed on different types of active sites. Below 3 atm. pressure the reactants competed for similar active sites. With platinum the apparent rate-controlling step was a surface reaction between dissociated hydrogen and a-methylstyrene on similar active sites. Rhodium and nickel catalyzed the polymerization a-methylstyrene together with slow hydrogenation. Ruthenium had negligible activity for catalyzing the hydrogenation under the moderate conditions used in this work.In all cases mass transfer resistances were negligible.

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