Aspartate aminotransferase from cotton seeds

Chemistry of Natural Compounds - Using fractionation with ammonium sulfate and ion-exchange chromatography on CM- and DEAE-celluloses, two fractions with aspartate aminotransferase activity have...     

Basicity and structure of 5-hydroxybenzimidazoles in nitromethane

Examination of the acid-base properties of 5-hydroxybenzimidazoles has shown them to exist in nitromethane as the 5-hydroxy-tautomers. Substituents in the 2-position have a predominantly inductive effect on the basicity of the 3-nitrogen, rationalized as in other nitrogen heterocycles by the proximity of the substituents to the reaction center.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. The Research Institute for Intermediates and Dyes, 103787 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 421–425, February, 1992.     

Synthesis and electrophysical characteristics of VO2-based nanostructures with a complicated architecture on a silicon surface

Nanofilms of complicated architecture based on VO₂ and containing chromium were synthesized by the molecular layering method. The study of electrophysical characteristics of vanadium dioxide nanocrystallites and of VO₂-containing chromium has shown that semiconductor-metal phase transitions appear in the ranges of 130–160 and 100–110 K, respectively. The introduction of a transition-element ion in the nanostructures based on VO₂ affects the phase transition characteristics.     

Adhesion-strong polymeric layers on polyethylene terephthalate films modified by irradiation with accelerated electrons

Regular trends in variation of the functional group composition, surface energy, and amorphous-crystalline structure of oriented polyethylene terephthalate films modified by irradiation with accelerated electrons to the absorbed dose in the range 25–300 kGy were studied by the methods of surface tension, indicator dye adsorption, and X-ray diffraction. The possibility of preparing gelatin emulsion layers exhibiting high adhesion strength was examined.     

Thermal stability of modified chromium dioxide nanopowders with various magnetic properties obtained by hydrothermal route

Melt modification is a method commonly used when enhancing mechanical and microstructural properties of various alloys. The addition of heterogeneous nucleation sites generally refines the given microstructure and enhances the toughness of the material. Ferroalloys based on high-melting elements require a longer incubation time in the melt which makes them liable candidates for modification agents. A research on the effect of melt modification was conducted on an indefinite chill cast iron alloy commonly used for working layers in rolls. The goal of the research was to determine the effect of ferrovanadium and ferrotungsten melt treatment with the use of thermal analysis along with thermodynamic modelling using the CALPHAD approach. The results show a decrease in the measured liquidus temperature of the modified alloy along with a possible second eutectic reaction hidden inside the main graphite/cementite eutectic reaction. Scanning electron microscopy revealed small and evenly distributed MC type carbides rich in V with W and other carbide-forming elements. The results presented in this work enable a better understanding of the impact melt modification has on the development of microstructure and subsequently the improvement in mechanical properties of the alloy.     

The structure of electron beam-modified cellulose triacetate

The structure, relaxation, and surface properties of cellulose triacetate (CTA) fibers and films modified by electron-beam irradiation in the absorbed dose range of D = 0−1000 kGy have been studied. The relation of the glass transition and melting temperatures of the irradiated CTA samples with the local density and the fractal dimensionality of the macrochain has been revealed. It has been shown that the radiation-chemical processes associated with the rupture of acetal bonds and the hydrolysis of CTA acetate groups predetermine the change in the structural and relaxation characteristics of the irradiated samples, as well as a nonmonotonic form of the dependence of the density and the surface energy of the films upon the absorbed dose near the threshold value of D = 75 kGy.