Preparation of Polyoxometalate-Stabilized Colloidal Solutions of Palladium Metal and Catalysts Supported on Them

Sols containing Pd(0) clusters with polyoxo anions are prepared by the reduction of colloidal solutions of polyhydroxo complexes of Pd(II) in the presence of Mo(VI), W(VI), V(V), and Nb(V) polyoxo anions. The cluster sizes varied within the limits of 1–10 nm depending on the nature of the polyoxo anion. The stability of sols toward coagulation depends on the ratio between the palladium and polyoxo anion amounts in solution and on the composition of the solvent. Supported Pd catalysts are obtained by the adsorption of particles from sols; Pd can exist in these catalysts as individual particles or associates or form filamentary structures.     

Heat effect of pulsed laser radiation on the real structure of CdTe single crystals

Real structure modification of CdTe single crystals exposed to pulsed radiation of ruby and Nd: YAG lasers is investigated using X-ray diffraction topography in the reflection configuration. The changes are mostly due to effects of heat in a thin surface layer. Depending on the incident laser energy, the following significant changes in the real structure of the crystal surface layer are observed: (1) integral improvement of the surface structure due to microstress relaxation; (2) the formation, development, and degradation of an ordered twin structure in the process of recrystallization; and (3) the formation of a fine-mesh dislocation structure. All these changes barely affect the bulk of the crystal. Mechanisms of the modifications are discussed, along with possibilities for their monitoring and control.     

Scattering of solitons in the formalism of the Darboux transform

By means of the technique of Darboux transformations formulas are obtained which describe the scattering of solitons in the Kadomtsev-Petviashvili equations; the KdV equation, the nonlocal KdV equation, the two-dimensionalized Toda lattice and its periodic reductions, and, in particular, the sine-Gordon equation.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 12, pp. 136–141, 1982.     

Study of selective Fischer-Tropsch catalysts synthesized by the destruction of bimetallic carbonyl complexes on activated γ-Al2O3 support

The bimetallic catalysts obtained by the deposition of a Fe?Co binuclear cluster on the dehydroxylated γ-Al₂O₃ are studied and compared to some other relative systems. These bimetallic catalysts are found to be active and selective in olefin synthesis. This is connected with the formation of Fe?Co contact which is detectable by Mössbauer spectroscopy.     

Effect of γ radiation on the polarization properties of polyethylene oxide

The effect of γ radiation on the dielectric properties of polyethylene oxide is investigated by the polarization-current method. It is found that polarization currents in a γ-irradiated sample decrease in magnitude, which indicates a lower probability of forming a crystalline phase.