Wavevector scaling,surface critical behavior,and wetting in the 2-d, 3-state chiral clock model

The controversial 2-d, 3-state chiral Potts model is studied using transfer matrix finite size scaling. at =0, we find dq _N/dN ^–4/5, whereq is the wavevector, the chiral field, andN the strip width (N=4–10). The result is consistent with den Nijs's crossover exponent =1/6. With surface fields on the infinite free boundaries, exponents associated with bulk magnetizationy _H, surface magnetizationy _H, and surface susceptibility are computed vs. ; results are similar for or to the infinite direction. Preliminary results are given for the bulk specific heat critical amplitudes, to test the universality of amplitude ratios. The interface wetting line is located for 01/4 using simple transfer matrix calculations of surface tensions in the solid-on-solid approximation. Overhangs or bubbles seem relatively unimportant at all temperatures.     

Syntheses of Retinol Glycosides Using β-glucosidase in SCCO<Subscript>2</Subscript> Media

β-Glucosidase isolated from sweet almond catalyzed syntheses of water soluble retinol glycosides were carried out in SCCO₂ media with carbohydrates—D-glucose 2, D-galactose 3, D-mannose 4, D-fructose 5, and D-sorbitol 6. Retinol glycosides yields were in the 9–34% range. Reaction with D-fructose 5 gave a highest yield of 34%. Excellent regioselectivity was observed with D-mannose 4 and D-sorbitol 6 which gave exclusively C1β-mannoside and C1-D-sorbitolide.     

Extended fine structure analysis using electron beams

Appearance potential spectroscopy has found use primarily as a core level probe of the electronic structure of solid surfaces. The observation of extended fine structure above appearance potential edges, analogous to that observed above X-ray adsorption edges, gives promise that atomic spacings in the surface region may also be determined. Most previous studies of appearance potentials have depended on observing changes in the soft X-ray yield. Poor detection efficiencies and low flourescence yields have limited the usefulness of this approach. Using the secondary electron yield, however, we have recently succeeded in observing fine structure extending more than 400 eV above appearance potential edges. We are currently employing this approach to study the structure of SiO₂ films on Si substrates. Initial attempts at Fourier inversion and problems due to diffraction of the incident electron beam and multiple scattering effects will be discussed.