Synthesis and investigation of the electronic structure of molybdenum tetrasulfide and its lithium intercalates

An X-ray amorphous phase of molybdenum tetrasulfide with the analytical formula MoS₄ has been sythesized. Quantum chemical modeling of the suggested local structure of MoS₄ and EHT calculation of the electronic structure of the basic (Mo₂S₄)⁴⁺ fragment are reported. The electronic structure of molybdenum tetrasulfide and its lithium intercalates was investigated by X-ray emission and X-ray photoelectron spectroscopy. It is shown that the change in the electronic structure of the starting molybdenum tetrasulfide to four lithium atoms per formula unit in the intercalate may be considered in the rigid band model. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 727–734, July–August, 1996. Translated by L. Smolina     

Chlorinated polyimides

Photoinitiated reaction of maleic anhydride with chlorobenzene and o-chlorotoluene in the presence of a sensitizer (benzophenone) was studied with the aim to prepare chlorinated tricyclodecenetetracarboxylic dianhydrides. New halogenated polyimides were prepared by the reactions of these products with various diamides in N-methyl-2-pyrrolidone in the presence of catalysts.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1853–1857.Original Russian Text Copyright © 2004 by Zhubanov, Kravtsova, Mukhamedova.     

Composites based on doped polyaniline and polyimide with tricyclodecene structures in the backbone

Conducting composites based on an alicyclic polyimide and polyaniline doped with nonylnaphthalenesulfonic acid or with undoped polyaniline were prepared. Their physicomechanical and electrical properties were studied. The accelerating effect of conducting polymers on the polycondensation was demonstrated.     

Determination of the local atomic structure of the active center of bromoperoxidase protein via the analysis of x-ray absorption spectra

The existing model of the active center of bromoperoxidase protein, which has been obtained via x-ray diffraction methods, is defined more precisely. The processes occurring in the active center of this protein interacting with hydrogen peroxide are studied. It is shown that the existing model of the active center of bromoperoxidase is not sufficiently accurate. To study the adequacy of certain structural parameters of the active center, the atomic structure has been optimized using electron density functional theory. A new model of the active center of bromoperoxidase protein is proposed.     

Study of local atomic and electronic structure of titanium-containing forsterite based on analysis of X-ray absorption spectra

The local atomic structure of titanium-containing forsterite is investigated based on analysis of X-ray absorption near-edge structure (XANES) spectra. The Ti K-XANES spectra of the mineral under study are calculated for several possible structural models. Theoretical analysis of the X-ray absorption spectra is performed based on the full-potential finite-difference method. The local geometry of the titanium environment is determined by comparing the experimental Ti K-XANES spectrum with the theoretical spectra calculated for different structural models. The structural model where titanium atoms substitute for silicon ones is found to be most likely for titanium-containing forsterite. The calculated partial densities of electron states of titanium near the bottom of the conduction band of titanium-containing forsterite are analyzed.     

Analysis of the polarization dependence of the N K edge X-ray absorption fine structure in InN

The polarization dependence of the x-ray absorption near-edge structure (XANES) of InN beyond the N K edge is calculated. The XANES calculations are performed for different values of the angle θ between the XY plane of crystalline indium nitride and the incident x-radiation (θ = 15°, 30°, 45°, 60°, 75°, and 90°). It is shown that, in the case of N K XANES for InN, a strong polarization dependence of the specific features of the spectrum is observed. The calculated spectra are compared with previously measured experimental spectra. The partial densities of the electronic states of InN are calculated near the top of the valence band and near the bottom of the conduction band.     

Preparation and Study of New Metal-Containing Polymer Compositions Based on an Alicyclic Polyimide

New film-forming metal-containing polymer compositions based on an alicyclic polyimide and on arylalicyclic copolyimides synthesized from tricyclodecene-, oxydiphenyl-, and benzophenonetetracarboxylic dianhydrides and oxydianiline in the presence of cobalt, nickel, iron, and copper salts in amide solvents were prepared, and their main properties were studied. Optimum synthesis conditions and compositions of metalcontaining composites with improved thermal, electrical, and other characteristics were found. The possibility of using the modified alicyclic polyimide films for fabricating integrated circuits by magnetron sputtering was examined. The samples prepared by sputtering of metals onto SPI-1 polyimide films with a chromium sublayer are characterized by high adhesion of the metal to the film surface.     

Numerical solution of the problem of the mixing of the boundary layers shed from the trailing edge of a wing

During the mixing of viscous incompressible flows with different velocities, in the vicinity of a trailing edge an interaction region with a three-layer structure is formed, similar to that in the case of symmetric shedding with equal velocities. The boundary layers developing on the upper and lower sides of the airfoil form a viscous mixing layer, or vortex sheet, which separates the flows downstream of the trailing edge. The boundary value problem corresponding to the flow in the viscous sublayer in the vicinity of the trailing edge of a flat plate is solved for high Reynolds numbers using an efficient numerical method for solving the equations of asymptotic interaction theory.