Effect of Oxide Preparation Prehistory on Reduction in the System Al2O3-TiO2-nC and Properties of Al2O3-TiC Powder Formulation

The influence exerted by the dispersity and composition of the starting powder and by the temperature and time of treatment on the properties of Al₂O₃-TiC powder formulation was studied.     

Certain properties of bitopological spaces

Some connections and interrelations between T_i-separation axioms (i=1,2,3) for bitopological spaces are considered. In particular, four different versions of the definition of the pairwise Hausdorff separation axion are discussed. Bibliography: 3 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 231, 1995, pp. 135–140. Translated by O. A. Ivanov.     

The effect of oxygen on the excition spectra of A2B6 compounds

The exciton cathode luminescence and reflection spectra are studied for pure ZnSe with deviation from stoichiometry within a bilateral homogeneity region and a sharp change in the oxygen concentration from 3·10¹⁸ to 2·10²⁰ cm⁻³. It is confirmed that the exciton b and is not shifted and, consequently, that the forbidden band does not change with the oxygen concentration. This effect is interpreted on the basis of the interaction of oxygen with intrinsic point defects. It is found that dissolution, of oxygen enhances the excitonphonon interaction, which results in additional absorption within the A_ex-1LO or A_ex-2LO spectral region. It is shown that this effect is also characteristic of other compounds A₂B₆. Moscow Institute of Power Engineering, 14, Krasnokazarmennaya St., 111250, Moscow B-250, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 394–399, May–June, 1998.     

Mechanism of Nitrogen-Containing Cyclic Polymerization

Abstract

The comprehensive polymerization mechanism of the nitrogen-containing cycles 1-azobicyclo (3,1,0)-hexane (ABH), conidine, quinuclidine, and triethylenediamine under the action of quaternary ammonium salts, ammonium salts, and BF₃ complex with conidine is studied. Polymerization is of the living polymers type, and the active centers of monomer polymerization are ions and ion pairs: the activity of the latter is comparable to and exceeds that of the free ions. The effects of the nature of the counterion, cation, and medium polarity on the reaction rate are investigated. The polymerization rate is found to depend on the nature of the counterion in the polymerization of ion pairs, but not to depend on the counterion in the polymerization of free ions. The reaction rate is proportional to the counterion size in the polymerization of ion pairs. In the case of conidine K₊ = 0.2, K_±(Cl^?) = 0.28, K_±(Br^?) = 0.36, K_±(I^?) = 0.51, and K_±(ClO₄ ^?) = 0.62 (liter)/(mole)(min). The heats of nitrogen-cyclic polymerization are measured and correlated with the activation energy.     

Gas-chromatographic determination of traces of <Emphasis Type="Italic">O</Emphasis>-isopropyl methylphosphonofluoridate (sarin) in soils using its diastereomers

A procedure was developed for determining traces of O-isopropyl methylphosphonofluoridate (sarin) in soils at a level of 2 × 10⁻⁴ mg/kg. The procedure is based on solvent extraction with a hexane-benzene mixture, the preconcentration of the extract to a small volume, the synthesis of dialkyl esters using secondary alcohol aluminates, and gas-chromatographic separation on an HP-1 column with a flame ionization detector. The determination error does not exceed 29%; the time of analysis is 1 h.     

Saturated Vapor Pressure and Crystal Structure of Bis-(2-imino-4-pentanonato)copper(II)

A comprehensive study of copper(II) bis-ketoiminate including tensimetric analysis of sublimation and structure solution has been carried out. The temperature dependence of saturated vapor pressure over Cu(ki)₂ crystals derived by the flow method is expressed by the equation lnP_(atm)} = 25.31-13750/T, H _subl = -114.2 ± 1.3 kJ· mole^-1, S_subl =210.2 ± 3.0> J· mole^-1 · K^-1. Crystal data for CuO₂N₂C₁₀H₁₆: a=15.143(3), b=16.681(8), c=13.795(32) , space group Ccca, Z=12, d _calc = 1.47 g/cm³, R=0.029. The structure is molecular and consists of crystallographically independent Cu(ki)₂ complexes of two types, one with a cis structure and the other with a cis–trans disordering. The copper atom has a plane square environment of two oxygen and two nitrogen atoms. In the cis isomer, Cu–O 1.938 and Cu–N 1.895 ; in the disordered complex, all four Cu–O(N) distances are 1.901 .     

Studies on pyrazoles

A number of -amino acids of the pyrazole series have been synthesized by the direct Rodionov reaction and have been characterized by their UV spectra, electrophoretic mobility, and paper chromatography.For part LVIII, see [1].