Copolymerization of vinyl chloride with 1-(vinyloxyalkoxy)propylene oxides-2,3: Solvophobic effects of solvents

The influence of solvophobic effects of aprotic solvents on the reactivity of 1-(vinyloxyalkoxy)propylene oxides-2,3 in free-radical copolymerization with vinyl chloride has been studied by dynamic light scattering. It has been shown that the association of copolymer macromolecules in aprotic solvents results in the reduced reactivity of 1-(vinyloxyalcoxy)propylene oxides-2,3. This effect can be explained by a decrease in their local concentration in the vicinity of the reaction center.     

Spin-controlled Mott-Hubbard bands in LaMnO3 probed by optical ellipsometry

Spectral ellipsometry is used to determine the dielectric function of an untwinned crystal of LaMnO3 in the range 0.5-5.6 eV at temperatures 50相似文献   

Synthesis of 2-aminomethyl derivatives of dihydrothiazolo[2,3-f]xanthine

2-Aminomethyl derivatives of dihydrothiazolo[2,3-f]xanthine were obtained by the reaction of 8-halo-7-(2,3-epithiopropyl)xanthines with amines.Fifteenth Anniversary of the All-Union Lenin Young Communist League Bashkir State Medical Institute, Ufa 450000. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 840–842, June, 1991.     

Reaction of carbon tetrachloride with hydrogen peroxide

Reaction of carbon tetrachloride with aqueous hydrogen peroxide in the presence of anhydrous iron(III) chloride was studied. Optimal conditions for the preparation of phosgene were found on the basis of analysis of the kinetic data and mechanism of the process. The reaction rate and yield (the latter reaching 95% in the stationary mode) are determined mainly by the amount of the heterogeneous catalyst. According to the experimental data, the reaction follows a radical mechanism.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1455–1458.Original Russian Text Copyright © 2004 by Tatarova, Trofimova, Gorban, Khaliullin.     

3,5-dibromo-1-(1,1-dioxothietanyl-3)-1,2,4-triazole, new reagent for preparation of substituted thietane 1,1-dioxides

A new reagent, 3,5-dibromo-1-(1,1-dioxothietanyl-3)-1,2,4-triazole, was introduced for the synthesis of 3-substituted thietane 1,1-dioxides that were treated with sodium alcoholates and phenolates to prepare 3-alkoxyand 3-aryloxythietane 1,1-dioxides.     

Spin polaron theory for the photoemission spectra of layered cobaltates

Recently, strong reduction of the quasiparticle peaks and pronounced incoherent structures have been observed in the photoemission spectra of layered cobaltates. Surprisingly, these many-body effects are found to increase near the band-insulator regime. We explain these unexpected observations in terms of a novel spin-polaron model for CoO2 planes, which is based on a fact of the spin-state quasidegeneracy of Co3+ ions in oxides. Scattering of the photoholes on spin-state fluctuations suppresses their coherent motion. The observed "peak-dip-hump" type line shapes are well reproduced by the theory.     

Enhanced pairing correlations near oxygen dopants in cuprate superconductors

Recent experiments on Bi-based cuprate superconductors have revealed an unexpected enhancement of the pairing correlations near the interstitial oxygen dopant ions. Here we propose a possible mechanism--based on local screening effects--by which the oxygen dopants do modify the electronic parameters within the CuO2 planes and strongly increase the superexchange coupling J. This enhances the spin pairing effects locally and may explain the observed spatial variations of the density of states and the pairing gap.