Hyperfine magnetic fields at sp-sites in Co2YZ Heusler alloys

The systematics of hyperfine magnetic fields at sp impurities on the Z-sites in Co based Heusler alloys are investigated. New TDPAC measurements of Cd hyperfine fields are reported.     

Gel electrophoresis as a means of detecting ternary complex formation of thymidylate synthetase

Polyacrylamide gel electrophoresis was used to resolve as many as three protein components from incubation mixtures containing the inhibitor, 5-fluoro-2′-deoxyuridylate, the cofactor, 5,10-methylene tetrahydrofolate, and thymidylate synthetase. In a series of mixtures containing excess 5,10-methylenetetrahydrofolate and constant levels of thymidylate synthetase, the relative amounts of the protein components were shown to be dependent on the concentration of the inhibitor. Evidence is presented which suggests that the three protein components correspond to (1) native enzyme, (2) an inhibitor-cofactor-enzyme complex in a 1:1:1 molar ratio, and (3) an inhibitorcofactorenzyme complex in a 2:2:1 molar ratio, respectively. Ternary complexes of thymidylate synthetase are stable to gel filtration and are shown to undergo a relatively slow rate of breakdown on storage at 25 °C.     

Solvents showing the external heavy atom effect in phosphorimetry

Ten solvents containing heavy atoms were examined for suitability for use in the external heavy atom effect for routine phosphorimetry. In previous work only iodine-containing solvent systems have been used, and the incongruity of enhancement results for structurally similar compounds suggests that the ultraviolet transmission characteristics of the solvent systems may be responsible for fractional enhancements. In this study the effect of chlorine-, bromine-, and iodine-containing solvent systems on phosphorescence and fluorescence intensities was investigated. Generally, chlorine-, and bromine-containing solvent systems showed a significant improvement in phosphorimetric enhancements with slightly longer lifetimes than in solvent systems containing iodine. As expected from their smaller spin-orbit coupling, chlorine-containing solvent systems yield smaller enhancements than bromine-containing solvent systems. Solvent systems containing bromine seem to offer the best compromise between ultraviolet transmission characteristics and large spin-orbit coupling constants.     

A chromatographic comparison of the pore structure of zirconia high performance liquid chromatographic materials made by the polymerization induced colloidal aggregation and the Oil Emulsion methods

Summary The pore structures of zirconium oxide particles prepared by two different methods (PICA and Oil Emulsion processes) are compared. Nitrogen sorptometry and size exclusion chromatography are used to characterize the two different types of particles. Significant and unexpected differences were found in the accessible pore volumes and the bed packing densities of the two materials. The PICA material was found to have a higher totally included and totally excluded volume than would be normally expected. The chromatographic method provides results which are more useful for the application of these materials to separation sciences.