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More interesting than the reaction of the aromatic compounds on the (0001 )-Zn polar surface was their reaction on the (OOOl)-O polar surface. Unlike the through C3 oxygenates and the alkynes, which did not react on the (OOOl)-O surface, the aromatic oxygenates were found to react on this surface. Benzoic acid, benzaldehyde, and phenol decomposed on the (0001 )-0 polar surface at high temperatures to produce CO, C02, H2, and H20. The XPS results clearly demonstrated that these aromatic compounds were stabilized on the (OOOl)-O surface via a direct interaction of the aromatic ring with the surface. This result serves to illustrate further the effects of surface crystallographic and electronic structure in determining the reactivity of metal oxide surfaces and suggests that different surface structures can lead to the activation of different functional groups.

Publication costs assisted by the National Science FoundationFrom measurements of the angular dissymmetry and autocorrelation function of laser light scattered from 2 g/dL aqueous solutions of sodium dodecyl sulfate (SDS) in 0.6 M NaCl, we have deduced both the mean radius of gyration, R,, and mean hydrodynamic radius, R h , of SDS micelles over a wide temperature range (15-85 "C) including the supercooled region below the critical micellar temperature (cmt). Above 40 "C, values of the angular dissymmetry function, d(O), defined as the ratio of scattered intensities Z(0)/Z(180° -0) (30" 5 0 5 go"), are less than 1.05 implying that R, is smaller than 100 A. Below 40 "C, d(0) values increase appreciably as the temperature is lowered and R, is found to increase from 121 8, at 30 "C to 380 A at 15.7 "C, indicating a substantial growth of micellar size. This growth is also reflected by an increase in the R h values from 101 to 195 A. A deduction of micellar shape is made by comparing the measured dependence of R, on R h with theoretical calculations, assuming either spherical, disklike or rodlike micellar growth. The data are found to be in excellent agreement with the predictions based on a rodlike micellar shape, a finding which confirms the previous conclusion of Mazer et al.

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PurposeTo develop models for rabbit, monkey, and human that enable prediction of the clearance after intravitreal (IVT) injections in one species from experimental results obtained in another species.MethodsAnatomically accurate geometric models were constructed for rabbit, monkey, and human that enabled computational fluid dynamic simulation of clearance of an IVT injected bolus. Models were constructed with and without the retrozonular space of Petit. Literature data on clearance after IVT injection of substances spanning a range of molecular weight up to 157 kDa were used to validate the rabbit model.ResultsThe space of Petit had a significant increase on the clearance of slowly diffusing substances cleared by the anterior pathway by reducing the bottleneck for drug efflux. Models that did not include this zone could not accurately predict the clearance of slowly diffusing substances whose clearance was accelerated by intraocular pressure-driven convection.ConclusionsThe ocular anatomy must be carefully reconstructed in the model to enable accurate predictions of clearance. This method offers an alternative means for scaling experimental data from one species to another that may be more appropriate than other simple approaches based entirely upon scaling of compartment volumes and flow rates.