Small-angle x-ray scattering in a carbon-sulfur nanocomposite produced from bulk nanoporous carbon

A new nanocomposite material containing approximately 50 vol % S is prepared by filling pores of bulk nanoporous carbon samples with sulfur. The initial nanoporous carbon samples are synthesized from polycrystalline α-SiC through the chemical reaction. A comparative investigation of small-angle x-ray scattering (SAXS) is performed for the prepared nanocomposite and the initial material. The possible changes in the scattering power of the initial material upon filling of its pores with sulfur are considered in the framework of a simple model. The regularities revealed are used to interpret the experimentally observed changes in the scattering power. The size distribution functions of incorporated sulfur nanoclusters in the nanocomposite (or filled nanopores in the initial material) are determined within the Guinier approximation. It is demonstrated that the smallest sized pores (8–16 Å) remain unfilled, whereas the filling factor for larger sized pores can reach several ten percent by volume. The conditions favorable for small-angle x-ray scattering upon filling of the nanopores are analyzed.     

Effect of surface catalytic activity on nonequilibrium heat transfer in a subsonic jet of dissociated nitrogen

The present paper investigates experimentally and numerically the effect of the heterogeneous recombination of atoms on the heat transfer of models in a subsonic jet of dissociated nitrogen for the conditions of an experiment in the VGU-2 plasma generator and determines the effective probabilities of the heterogeneous recombination of nitrogen atoms for a number of materials at high temperatures.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 166–172, May–June, 1985.     

Opportunity for magnetic field spatial‐time correlation research using a μSR^2‐method

It is theoretically shown that in rare gases at P < /100 atm the external electric fields of the order of 100 V/cm could significantly change the value of electron density in the region of μ^- or μ⁺ stopping point and affect the muonic atoms formation in plasma‐chemical reactions. The kinetic model of processes which might explain the results of μSR‐experiments for μ^- in Ne and Ar both with and without external electric field is proposed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Investigation of the extent, rate, and mechanisms of electron-stimulated modification of the C60 fullerite by EELS

A parameter representing the intensity ratio of the two features in the characteristic electron energy loss spectrum that are most sensitive to electron irradiation is proposed for use in characterizing the extent of electron-stimulated modification of fullerite. By normalizing this parameter, we succeeded in obtaining a universal scale for the extent of modification that can be unambiguously related to the π-electron density. The dose dependence of this parameter is shown to be described by one exponential, thus permitting one to conclude that both the polymerization and amorphization of the fullerite are dominated by one mechanism, namely, the formation of intermolecular chemical bonds, which is stimulated by valence-electron excitation. The rate of the electron-stimulated modification, or the dose susceptibility of the material, is defined through the derivative of this parameter. The dependence of this rate on the incident electron energy is obtained. It is shown that structural changes are mainly due to a swarm of numerous secondary and decelerated electrons rather than to the primary electron.     

Photoluminescence spectra of ultradisperse diamond

The first study of materials based on ultradisperse diamond produced by detonation is reported. A luminescence band in the visible has been observed, and some of its structural features have been interpreted by analogy with the known luminescence bands of centers in synthetic and natural diamonds. A comparison of the spectra obtained from ultradisperse diamond samples with the surface modified by different chemical treatments suggests that their pattern is governed to a considerable extent by the presence of a graphitic layer on the grain surface. Fiz. Tverd. Tela (St. Petersburg) 39, 2156–2158 (December 1997)     

Synthesis of 1h-pyridazin-4-one derivatives from acetylagetone through its difluoroboryl chelate

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, p. 1690, July, 1988.