Electric properties of single-crystalline nickel films deposited by the method of chemical transport reactions

The conditions for obtaining single-crystalline nickel films with a high resistivity ratio at room temperature and at 4.2 K (up to 1000) are described. The thicknesses of the films studied fall in the range 0.7–10 m. The meanfree path length of the carriers (6–7 m) and the specularity parameter (0.05) are determined using the Fuks-Sondheimer method.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 12–15, April, 1986.     

Observation of a new surface state on4He crystal interfaces

The equilibrium shape ofhcp ⁴He crystals has been studied at temperatures 0.05≤T≤0.7 K by means of a high precision optical interferometer. We find that the profile of the interfacial boundary, close to an almost horizontal c-facet, has a well-defined slope discontinuity separating two angular regions with different behavior of the surface stiffness. For surfaces tilted by an angle ϕ≤100 μrad with respect to the c-facet, we obtain, contrary to the linear angular dependence predicted by current theories.     

Steady-state acceleration of alkali plasma in external crossed electric and magnetic fields

The results of an experimental investigation of the electromagnetic acceleration of an alkali plasma in single- and double-stage E,H-accelerators are discussed. The nature of the discharge in accelerators with ceramic and metallic walls is investigated. The number of elements of the metallic wall necessary for preventing breakdown is determined. The thrust and efficiency of different constructions are determined, and their efficiencies and effectiveness are compared.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 20–30, November–December, 1974.The authors thank Yu. A. Tetyukhin, M. G. Shevtsov, V. G. Mikhalev, and B. S. Dimanov for participation in the experiments.     

Electrohydraulic effect in heterodisperse water-plant systems. II. Chemical nature of the suspended particles

On the basis of the results of acid hydrolysis, chromatographic analysis of the hydrolysates, and a study of IR spectra, it has been established that the suspended particles liberated under the action of electrohydraulic shocks on heterodisperse water—plant systems consist of small fragments of the lignocarbohydrate complex of the plant tissue.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. FAX (3712) 62 73 48. Division of Wood Chemistry, Irkutsk Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences. Institute of Solar and Terrestrial Physics, Siberian Division of the Russian Academy of Sciences, Irkutsk, FAX (395-3) 46 25 57. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 435–439, May–June, 1994.     

Quantitative1H and13C NMR spectroscopy of lignins from an aqueous ethanolic cook of aspen wood

General and comparative characteristics obtained by¹H and¹³C NMR spectroscopy of the lignins from aqueous ethanolic cooks are presented. It is shown that degradation of the lignin macromolecule takes place during the digestion of aspen wood. The mean length of the lignin side chains decreases and ether bonds are cleaved, while the degree of condensation of the substances increases.Irkutsk State University. Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 277–285, March–April, 1993.     

Mechanical and physicochemical properties of matrices for fiber reinforced plastics based on low-melting phthalonitrile monomers

The mechanical properties of cured phthalonitrile matrices for fiber reinforced plastics (FRP) based on low-melting phenylmethylsilanediyl-bis[oxymethylene(1,4-phenylene-4’-oxyphthalodinitrile)] (1) or its mixture with 1,3-phenylene-bis(oxy-4-phthalodinitrile) (2, comonomer) were studied. The flexural strength, Young’s modulus, fracture toughness, and some other characteristics of the cured resins based on monomer 1 (PN-1) and the mixture of monomers 1 and 2 (PN-1m) were determined. It is noted that the PN-1 resin can be processed by vacuum infusion and the PN-1m resin can be processed by compression injection molding. The developed resins are promising as materials for high-tech aerospace applications.     

Role of hydroxyl production and heat release in the two-zone fuel-rich adiabatic dimethyl ether/air flames at atmospheric pressure

Fuel-rich laminar adiabatic flames of premixed dimethyl ether/air mixtures at a high initial temperature and atmospheric pressure have been studied by numerical simulation and sensitivity analysis. These flames, having two heat release zones, are of great interest as an unusual and little-studied subject. We have investigated the chemical processes occurring in the two zones and analysed the mechanism of heat release in the flame. It has been found that the key reactions that have a significant influence on the flame speed are those involving dimethyl ether and the products of its incomplete oxidation. Calculation of the heat release rate confirms the presence of two heat release zones in the flame. A comparison of the reactions making a major contribution to the heat release with those significantly affecting the flame speed indicates that the main factor determining the flame speed is the formation of hydroxyls, rather than heat release. Analysis of the flame speed sensitivity shows that in the case of a two-zone structure of the flame, its speed is mainly determined by the reactions taking place in the low-temperature zone. That is, the cool zone with a higher temperature gradient is the leading one.     

Determination of the effective nuclear charge for free ions of transition metals from experimental spectra

The refined set of values of the effective nuclear charge (\(\bar Z_{ef} \)) and the set of one-electron spin-orbital constants (ξ _3d ^teor ) are obtained for ions of transition metals with the help of a semiempirical method of calculation of the spectrum of free ions with allowance for the spin-orbital interaction. The effective nuclear charge, which is a variable theoretical parameter, was determined from a comparison of theoretically calculated ion absorption spectra with experimental ones. The form of the potential for the calculation of the spin-orbital constant was chosen such that the calculated value ξ _3d ^teor would coincide with the experimental one ξ _3d ^exp . The calculated set of values \(\bar Z_{ef} \), ξ _3d ^teor } can be used in semiempirical calculations of energy levels of 3d ions (ions with an incomplete 3d shell).