Esters of ethylphenylthioarsinic acid

Conclusions The authors have obtained certain esters of ethylphenylthioarsinic acid and studied their properties.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 715–718, March, 1969.     

Hydrogenation of the nanopowders that form in a carbon-helium plasma stream during the introduction of Ni and Mg

Composite nanoparticles consisting of magnesium, nickel, and carbon atoms are studied both theoretically and experimentally. The calculations performed in terms of the density functional theory show that the jump frequency of hydrogen atoms in nickel-containing magnesium hydride increases substantially near impurity nickel atoms; as a result, the rate of hydrogen absorption by magnesium also increases. Nickel on the magnesium surface is shown to be absorbed via an island growth mechanism. Composite Mg-C, Ni-C, and Mg-Ni-C powders are produced by plasmachemical synthesis in a carbon-helium plasma stream. Hydrogen is introduced into a chamber during synthesis. It is found by X-ray photoelectron spectroscopy and thermogravimetric analysis that, among these three composites, only Mg-Ni-C contains magnesium fixed in the MgH₂ compound. The process of such “ultrarapid” hydrogenation of magnesium, which occurs in the time of formation of composite nanoparticles, can be explained by the catalytic action of nickel, which is enhanced by a high temperature. Scanning electron microscopy micrographs demonstrate the dynamics of the dehydrogenation of Mg-Ni-C composite nanoparticles in heating by an electron beam.     

Optical and magnetic properties of iron garnet films with high defect density

We have used spectroscopic and magneto-optic methods to study the effect of defects on the transmission spectrum, thickness, refractive index, and period of the striated domain structure in thin iron garnet films exposed to fast neutron fluences of 4.5·10¹⁷ and 10¹⁹ cm^–2. We observed both a decrease in transmission and a smearing of the interference maxima. The decrease in the quality of the interference fringes was observed in the visible spectrum for these samples. It was due to increased diffuse scattering of light by nonuniformities whose dimensions were comparable to the wavelength of the scattered light. It was determined that radiation defect clusters had no influence on the film thickness, but they did significantly alter the wavelength dependence of the refractive index and increased the period of domain structure striations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 45–48, August, 1988.We wish to thank A. G. Shishkov for discussions of the experimental results.     

3-(4-Phosphoryl-4-methyl-2-oxopentyl)-3-hydroxyindolin-2-ones,the first phosphorus analogues of natural convolutamydines

1. Download high-res image (110KB)
2. Download full-size image

     

Model harmonic force fields of inorganic molecules and calculations of thermodynamic values of chemical compounds

In this article are discussed the methodical principles of the selection of inorganic groups of compounds and finding their force fields, the main feature of which is the requirement for a monotonic variation of each force constant of the force fields of groups of molecules in the K_i(ij)–N_E(X) coordinates, where K_i(ij) is the force constant, N_e(X) is the atomic number of the central (E) or peripheral (X) atom of the molecules in a given subgroup of the Periodic system. It was shown that the monotonicity of these dependences is maintained in isostructural and isoelectronic groups of molecules. Numerous data are given on the force constants and of normal vibration frequencies of molecules formed by atoms of the III, IV, VI, and VII groups of the Periodic system.GIPKh Scientific-Production Association. State Institute of Applied Chemistry. Moscow Municipal Association Tekhnokhim. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 83–93, January–February, 1993.     

Voltammetric stripping analysis of metal concentrates with polymers soluble in aqueous solutions

The conditions were worked out for the simultaneous stripping voltammetric determination of components of the ternary Pb(II)-Cu(II)-Cd(II) and binary Ag(I)-Cu(II) systems at a carbon-paste electrode in 2% aqueous solutions of the water soluble polymer polyethyleneimine (PEI) and its thiourea-containing derivative (TU-PEI). Water-soluble polymers are shown to reduce the mutual effects of the components of the binary and ternary system at the electrode surface. The different complex stability of Ag(I), Pb(II) or Cd(II) and Cu(II) with PEI and TU-PEI allows Ag(I), Pb(II) and Cd(II) to be determined in the presence of a large excess of Cu(II).     

Determination of selenium(IV) by cathodic stripping voltammetry using a copper-modified mercury-film electrode modified with copper

The behavior of selenium(IV) at a mercury-film electrode previously modified with copper was studied by cathodic stripping voltammetry using an automatic system for replacing solutions without opening the circuit. The effect of chemical (the composition and concentration of the supporting electrolyte, the concentrations of mercury (II) and copper(II)) and electrochemical parameters (the potential and time of electrolysis) on the analytical signal of selenium was studied at each stage of the stripping cycle (the formation of the mercury-film electrode modified with copper, the electrochemical preconcentration of selenium, and the subsequent stripping of the concentrate). The detection limit for selenium(IV) was found to be 40 ng/L (5.0 × 10^?10 M) at an electrolysis time of 10 min.     

Neutrino signal at Baikal from dark matter in the Galactic Center

We discuss neutrinos originating from dark matter in the Galactic Center and present sensitivity of Baikal Gigaton Volume Detector to this signal.