Ultrasonic drawing of tungsten wire for incandescent lamps production

An influence of ultrasonic treatment (drawing) on structure, high temperature durability, evaporation and creep behaviours of tungsten single crystal and wires were investigated. A relation of tungsten wires properties with dislocation distribution was determined.     

Optical vortex solitons in parametric wave mixing

We analyze two-component spatial optical vortex solitons supported by parametric wave mixing processes in a nonlinear bulk medium. We study two distinct cases of such localized waves, namely, parametric vortex solitons due to phase-matched second-harmonic generation in an optical medium with competing quadratic and cubic nonlinear response, and vortex solitons in the presence of third-harmonic generation in a cubic medium. We find, analytically and numerically, the structure of two-component vortex solitons, and also investigate modulational instability of their plane-wave background. In particular, we predict and analyze in detail novel types of vortex solitons, a "halo-vortex," consisting of a two-component vortex core surrounded by a bright ring of its harmonic field, and a "ring-vortex" soliton which is a vortex in a harmonic field that guides a ring-like localized mode of the fundamental-frequency field.     

Synthesis of nitrogen- and oxygen-containing macrocycles by palladium-catalyzed amination of 3,24-bis(6-chloropyridin-2-yloxy)cholane

3,24-Bis(6-chloropyrdin-2-yloxy)cholane prepared from cholane-3,24-diol by the Mitsunobu reaction was successfully used to synthesize various polyaza macrocycles via palladium-catalyzed amination with linear polyamines. The contribution of side formation of cyclic oligomers was found to depend on the polyamine nature.     

Surface-activated and matrix-assisted laser desorption/ionization mass spectrometry of organotellurium compounds

Various types of ionization of organotellurium compounds in mass-spectrometric study are considered, with diphenyl telluroxide as example. The mass spectra of diphenyl telluroxide are presented. The possibility of applying surface-activated and matrix-assisted laser desorption/ionization mass spectrometry to organotellurium compounds is examined.     

Arylation of adamantanamines: II. Palladium-catalyzed amination of dihalobenzenes with adamantylalkanamines

Palladium-catalyzed arylation of various (1-adamantyl)alkanamines with isomeric (ortho, meta, and para) bromochloro- and dibromobenzenes was studied. Optimal catalytic systems were found for the synthesis of mono- and diamination products, and the dependences of their yields on the nature of the initial amine and dihalobenzene and on the amount of base were examined. Side amination products were isolated, and paths of their formation were analyzed.     

Isothiocyanates as derivatization reagents in the determination of 1, 1-dimethylhydrazine by gas chromatography coupled with mass spectrometry

Alkyl isothiocyanates were proposed for the determination of 1, 1-dimethylhydrazine (DMH) in the form of 4-alkyl-l, l-dimethylthiosemicarbazides by gas chromatography coupled with mass spectrometry (GC-MS). 4-Alkyl-l, l-dimethylthiosemicarbazides are selectively formed under mild conditions in the absence of catalysts. During the chromatography, these thiosemicarbazides are efficiently resolved from excess of alkyl isothiocyanates. A possibility of identification of DMH derivatives on the basis of the chromatographic retention parameters and fragmentation data under electron ionization conditions was demonstrated.     

First non-zero terms for the Taylor expansion at 1 of the Conway potential function

The Conway potential function ∇ _L (t ₁,...,t _l ) of an ordered oriented link L = L ₁ ∪ L ₂ ∪ ... ∪ L _l ⊂ S ³ is considered. In general, this function is not determined by the linking numbers and the Conway potential functions of the components. However, the first two nonzero terms of the Taylor expansion at the point 1 of the function ∇ _L are determined by the linking numbers only. We give the explicit formulas for these terms using summation over trees with l vertices.     

Interaction of Ytterbium Trifluoride with Zirconium in a NaF-ZrF4 Molten Mixture

The interaction of ytterbium trifluoride with zirconium in a molten mixture of sodium and zirconium fluorides have been studied by differential thermal analysis, X-ray diffraction, and electronic and IR spectroscopy. In the temperature range 440–640°C, zirconium reduces YbF₃ to ytterbium. The reaction products also contain low-valence zirconium and ytterbium compounds.     

Electronic structures and reactivities of derivatives of 1,4-dihydropyridines. 3. Enthalpies of elementary processes in the 1,4-dihydronicotinamide series

The heat effects of the elementary processes involved in electron and hydrogen transfer with the participation of 1,4-dihydropyridines were calculated by the semiempirical MINDO/3 method. The effect of a number of side and parallel processes on the kinetic principles is discussed in the case of the oxidation of 1-methyl-1,4-dihydronicotinamide. The calculated and experimental data are compared.See [1] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 63–66, January, 1988.