Vibration Properties of Thin Films of Transition 3d-Metals on the Cu (111) Surface

Russian Physics Journal - Using the potentials, generated by a tight binding approximation, the equilibrium atomic structure and the phonon spectra of Cr and Ni thin films (one monolayer) deposited...     

Optimization of Mass Transfer Processes in the Zone of the Air Electrode of a Fuel Cell with a Solid Polymer Electrolyte

A two-dimensional mathematical model for the transport of reactants in a fuel cell with a solid polymer electrolyte is developed. The model is used for analyzing spatial distributions of the concentration of reactants and current density over the cell. The effect of the catalytic-layer activity, reactant speed, bipolar-plate geometry, thickness and porosity of current collector and/or gas-diffusion sublayer, and the reaction mixture composition on the fuel cell efficiency is estimated theoretically and experimentally.     

Synthesis of N-β- trifluoroethyl derivatives of maleic and citraconic acids

Summary Halogen derivatives of the N-alkylmonoamides and N-alkylimides of maleic and citraconic acid containing the strongly electronegative group CF₃ in the alkyl radical, previously unreported in the literature, have been synthesized.     

Synthesis and nitration of NH- and N-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines

It has been shown that the most efficient catalysts for the synthesis of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine from 1,2,5-trimethylpyridin-4-one and acetylene under Trofimov conditions are rubidium and potassium hydroxides. Use of Triton B or a mixture of trimethylbenzylammonium chloride with rubidium hydroxide as catalyst gives O-alkylated oxime. Their configurations and conformations were established through separation of the individual isomers of 1-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines. Acetyl nitrate nitration of the cis isomer of this compound gave the 2- and 3-nitro derivatives. Similar nitration of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine gave the 2-nitro-7-hydroxy derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1375–1380, October, 1991.     

Synthesis and transformations of metallacycles. 30. Aluminacyclopentanes in the synthesis of secondary and tertiary alcohols

A method for the synthesis of secondary and tertiary alcohols was developed. The method is based on cycloalumination of olefins with trialkylalanes in the presence of Zr-containing catalysts followed by the CuCl-catalyzed in situ reaction of the corresponding aluminacyclopentanes with aldehydes or ketones.     

Biosynthesis of desosamine: construction of a new macrolide carrying a genetically designed sugar moiety

[formula: see text] The appended sugars in macrolide antibiotics are indispensable to the biological activities of these important drugs. In an effort to generate a set of novel macrolide derivatives, we have created a new analogue of methymycin and neomethymycin, antibiotics produced by Streptomyces venezuelae. This analogue 15 carrying a different sugar, D-quinovose, instead of D-desosamine, was constructed by taking advantage of targeted gene deletion combined with a specific pathway-independent C-3 reduction capability of the wild type S. venezuelae.