The Investigation of Recrystallization Processes of Ni Films

Electron diffraction and resistance methods are used to study the recrystallization process in nickel films. Recovery process, initial, and secondary recrystallization are observed in films in annealing. Unlike bulk deformed materials the distortions in films are produced in the process of their evaporation. The duration and sequence of stages of recrystallization are determined by the temperature of substrate in obtaining films and by the temperature of subsequent annealing. At temperatures of substrate above 150°C the reflexes due to recrystallized grains are observed just after evaporation of films. Temperature intervals of initial and secondary recrystallization of nickel films are calculated at temperatures of substrate equal to 130°C and 200°C. Correlation between the width of diffraction line, depending on the degree of lattice distortions, electrical resistance, measured at temperature of annealing and the number of recrystallized grains is noted. For reasons given it can be concluded that electron scattering in films takes place in lattice distortions in the crystallite and in their boundaries. The results obtained are of great interest in choosing optimum conditions for preparing films with given characteristics.     

New tetrasubstituted thioureas containing the 1-iminoethyl moiety

The reactions of 1,1,3-trisubstituted thioureas with acetonitrile afforded the corresponding tetrasubstituted thioureas containing the N-(1-iminoethyl) moiety.     

Crystal and molecular structure of N-(1-silatranylmethyl)phthalimide

By X-ray diffraction the crystal and molecular structure of N-(1-silatranylmethyl)phthalimide (SMP) is determined. The coordination polyhedron of the silicon atom in SMP, as in all silatranes, is a trigonal bipyramide; the phthalimide cycle is planar. The data presented indicate that the silatranylmethyl group almost does not affect the geometry of the phthalimide moiety.     

Triterpene saponins from Thalictrum minus. VI. Structure of thalicoside C

From the epigeal part ofThalictrum minus L. (Ranuncluaceae) we have isolated a minor cycloartane trisdesmoside — thalicoside C — 3,16,22(S),29-tetrahydroxy-9,19-cyclo-20(S)-lanost-24-ene 3-O--galactopyranoside 22,29-di-O--D-glucopyranoside. Its structure was established from the results of chemical transformations and of FAB-mass and NMR spectroscopies (¹H₁,¹³C,¹H-¹H₁, and¹³C-¹H).Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedeninii, No. 1, pp. 103–109, January–February, 1993.     

Properties of Flax Cellulose Solutions in Tertiary Amine N-Oxides and of Films Thereof

The solubility of flax fibers differing in the degree of purity in triethylamine N-oxide monohydrate was studied. The size and amount of the associates in equiconcentrated solutions were estimated from the turbidity spectra. Rheological properties of solutions of cotton and flax cellulose were compared. Hydrated cellulose films were obtained from solutions, and their physicomechanical properties were studied. The films were characterized by IR spectroscopy.     

Double Phosphinoboration of CO2: A Facile Route to Diphospha-Ureas

The reactions of CO₂ with a series of phosphinoboranes, including R₂PBpin (R=Ph, tBu; pin=pinacol), R₂PBMes₂ (R=Ph, tBu; Mes=2,4,6-Me₃-C₆H₂), and R₂PBcat (R=Ph, tBu, Mes; cat=catechol) are described. Although R₂PBpin and R₂PBMes₂ afford products of the form R₂PCO₂Bpin (R=Ph 1 , tBu 4 ) and R₂PCO₂BMes₂ (R=Ph 2 , tBu 3 ), respectively, R₂PBcat lead to further reaction affording the diphospha-ureas, (R₂P)₂CO (R=Ph 5 , tBu 6 , Mes 7 ), together with O(Bcat)₂. Computational studies provide insight into the mechanism, revealing an intermediate derived from double phosphinoboration of CO₂.     

Comparison of chemical effects of UV radiation from spark discharge in air and a low-pressure mercury lamp

The chemical effects of UV radiation from atmospheric-pressure spark discharge and a DBK-9 low-pressure mercury lamp in distilled water and aqueous solutions of hydrogen peroxide and tryptophan have been studied. Reactive species generated in water by the both radiation sources are HO ₂ ^· radicals, acid residue ions NO ₂ ^? and NO ₃ ^? , and ammonium ions. The yield of HO ₂ ^· radicals has appeared to be the same for both sources, (1.1–1.2) × 10^?6 mol L^?1 s^?1. This is confirmed by measurements of the degradation kinetics of tryptophan, which can be destroyed by HO ₂ ^· radicals. The pH of water monotonically decreases with time during the spark discharge treatment. In the case of the mercury lamp, the pH varies insignificantly because of the competition of NH ₄ ⁺ alkali ions with the acid residues. UV radiation plays the major role in the decomposition of hydrogen peroxide.     

Kinetics and mechanism of the photodecomposition of trifluorobromomethane and tetrafluorodibromoethane under the action of light with a wavelength of 253.7 nm

The kinetics of photodecomposition of Halons CF₃Br and C₂F₄Br₂ was studied at different times of the irradiation of a mixture of these substances with oxygen at the wavelength λ = 253.7 nm. Kinetic data were obtained from changes in the absorption spectra in the region of Halon absorption and at a wavelength of 416 nm, which corresponds to the absorption maximum of molecular bromine. Kinetic schemes were proposed for the photodecomposition of CF₃Br and C₂F₄Br₂ at λ = 253.7 nm, and the quantum yields of their photodecomposition at this wavelength were determined.     

Complex compounds of zinc and copper(ii) ions with dihydroquercetin and their antiviral activity

Russian Chemical Bulletin - Complex compounds of zinc and copper(ii) with trans-2R,3R-dihydro-2-(3,4-dihydroxy-phenyl)-3,5,7-trihydroxy-4H-1-benzopyran-4-one (dihydroquercetin) were synthesized...