Properties of Some Chitosan-containing Blends and Films Therefrom

Mixed solutions of chitosan and polymers with different chain rigidities (polyvinyl alcohol and methyl cellulose) in 2% acetic acid, at various component ratios, were studied viscometrically. The compatibility of the components in solutions and in the solid phase was assessed, and the mechanical characteristics of films prepared from these blends were determined.     

New data on gas-phase radical reactions in the steam reforming of methane in the presence of catalysts: I. Nickel catalysts

Methane pyrolysis and steam reforming were studied over a series of nickel catalysts (Ni-Al₂O₃, Ni/MgO, and Ni/LiAlO₂) under the same conditions (650-750°C, P_CH4 = 0.001-0.03 MPa). Unlike heterogeneous reaction of pyrolysis, some of the steps of steam reforming of methane occur in the gas phase. When gasphase reactions were suppressed, the rate and activation energy of steam reforming are close to the corresponding kinetic characteristics for pyrolysis. Hypothetically, the rate-limiting step of the process is the dissociative adsorption of methane on nickel in this case.     

Catalytic Steam Reforming of Methane: New Data on the Contribution of Homogeneous Radical Reactions in the Gas Phase: II. A Ruthenium Catalyst

The kinetics of methane steam reforming and pyrolysis on Ru/Al₂O₃(T= 650–750°C, = 0.001–0.030 MPa) is studied. The values of the rates and activation energies are compared with the kinetic parameters for nickel catalysts. It was shown that steam reforming can occur on the ruthenium catalyst both heterogeneously and heterogeneously–homogeneously depending on the reaction conditions. Comparative activities of the Ru/Al₂O₃and Ni–Al₂O₃catalysts are discussed under the conditions of purely heterogeneous and heterogeneous–homogeneous steam reforming.     

Complete reorganization of the mode structure of the wave function of a channeled electron in a crystal with a superlattice

The dynamics of relativistic electrons subjected to planar channeling in distorted crystals is investigated using step-by-step numerical integration of the Schrödinger equation. It is shown that periodic distortion of a planar channel (the formation of a “superlattice”) can cause complete reorganization of the mode structure of the wave function. In the limit of weak perturbations of the crystal lattice, the simulation results are consistent with the analytical results from perturbation theory. The position of each line in the spontaneous emission spectrum in the case of resonant distortions depends on the length of the superlattice period.     

Physicochemical properties of ionic liquid mixtures containing choline chloride,chromium (III) chloride and water: effects of temperature and water content

The effects of water addition and temperature on some physicochemical properties of room temperature ionic liquids containing chromium chloride, choline chloride and water in the molar ratio of 1:2.5:x (where x = 6, 9, 12, 15 or 18) have been studied. The density, viscosity, surface tension and conductivity of the liquid mixtures were measured for the temperature range of 25 to 80 °C. Increasing both water content and temperature resulted in decreasing density, surface tension and viscosity and increasing electrical conductivity. The average void radii (hole sizes) for the liquid systems under study were calculated; they were in the range of 1.21 to 1.82 Å. The average hole size was stated to grow with increasing both temperature and water content in the mixture. The variation of the average void radii correlates with the change in viscosity and conductivity. The activation energies of viscous flow and conductivity diminishes with increasing water content in the liquid mixture. There is a strong linear correlation between conductivity and fluidity which indicates that the conductivity of the ionic liquid mixtures is generally controlled by the ionic mobility. A moderate viscosity and higher conductivity of the Cr(III)-containing ionic liquids with extra-water addition (at x > 9) make them suitable for the development of chromium electrodeposition processes.     

On the problem of an inhomogeneous sphere placed in a homogeneous alternating magnetic field

The results of a numerical analysis of the equivalent magnetic moment of a two-layered sphere magnetized by a homogeneous alternating magnetic field are reported. The particular case of a hollow sphere is examined. It is found that for values of the parameter 60, the hollow sphere has the same magnetic moment as a solid sphere.     

Researches on pyrazoles

The pyrazole ring is opened by sodamide to give the corresponding -iminonitriles.For Part L see [11].     

On the “supercollimation” of X-ray beams in rough interfacial channels

The transmission of x rays through rough submicron narrow channels is investigated by numerical simulation with diffraction and decay of coherence taken into account. It is found that transmission is strongly increased for directions within the diffraction limit λ/d (d is the channel width). For larger angles strong roughness scattering results in rapid decay of coherence and absorption of the x-ray beams. When the coherent part is a significant portion of the transmitted beam, its divergence is also within the diffraction limit, which can be an order of magnitude smaller than the Fresnel angle of total external reflection. The effects are explained with the statistical theory of x-ray scattering in a rough transitional layer. Such “supercollimation” can be used for fine angular discrimination of x radiation and for the production of very narrow diffraction-quality x-ray beams. Zh. éksp. Teor. Fiz. 69, No. 10, 686–690 (25 May 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Unsteady-state performance of NOx catalytic reduction by NH3

Experimental results of studying NO_x catalytic reduction by NH₃ under periodic reversals in the direction of filtration of the mixture purified in a catalyst bed are discussed.

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NO_x .