Acrylonitrile copolymer nanofibers and their structural characteristics

Nanofibers of an acrylonitrile copolymer (acrylonitrile-methacrylate-itaconic acid) are obtained by the electrospinning method from 51.5% NaSCN aqueous solutions at a voltage of 15 kV. The structural characteristics of these nanofibers are investigated. It is shown that, during electrospinning, the interplanar distance decreases and reflections in the range 2θ ≈ 29.5° become narrower; sorption ability likewise decreases relative to that of microfibers.     

Almost Everywhere Convergence of Multiple Trigonometric Fourier Series of Functions from Sobolev Classes

Mathematical Notes - In this paper, we study the almost everywhere convergence of spherical partial sums of multiple Fourier series of functions from Sobolev classes. It is proved that almost...     

Simulation of fractal cluster growth on a substrate under ion bombardment

Ion-stimulated growth of a fractal cluster on the substrate is simulated in regimes that are intermediate between diffusion- and reaction-limited aggregations. It is shown that the fractal dimension of a growing cluster and the type of formed epitaxial structure are due to the sequence of ion-stimulated processes with different fractal dimensions. The algorithm for revealing the ion stimulation mechanism of processes based on fractal laws is proposed.     

Complexes of acetic acid α-(N-benzoxazolin-2-one) with Zn(II), Cu(II), and Co(II): Syntheses and crystal structures

The results of syntheses and X-ray diffraction analyses of mononuclear complexes [ML₂(H₂O)₄] (M = Co²⁺(I), Cu²⁺(II), and Zn²⁺(III)) containing water molecules and anions of acetic acid α-(N-benzoxazolin-2-one) (L = C₉H₆O₄) are presented. The crystals of complexes I–III are isostructural (space group P2₁/n, Z = 2) and are built of discrete neutral complex molecules. The crystallographic data are as follows: for complex I, a = 6.1470(5), b = 5.3310(3), c = 30.5894(17) Å, β = 95.056(6)°, V = 998.50(11) ų; for complex II, a = 5.9661(6) Å, b = 5.1414(4) Å, c = 32.672(2) Å, β = 92.395(6)°, V = 1001.33(14) ų; and for complex III, a = 6.1404(3) Å, b = 5.3476(2) Å, c = 30.5865(12) Å, β = 94.708(4)°, V = 1000.96(7) ų. The metal atoms (M) of the complexing agents are localized in the crystallographic symmetry centers and have a distorted octahedral environment due to two oxygen atoms of the carboxy groups of two monodentate ligands (L) and four water molecules. The M-O(1w)(H₂O) and M-O(2w)(H₂O) bond lengths for the indicated complexes are 2.088(3) and 2.118(3), 2.446(3) and 1.971(3), and 2.113(4) and 2.093(3) Å for M = Co²⁺, Cu²⁺, and Zn²⁺, respectively. The crystal structures are formed due to packing of chains built of inter-molecular hydrogen bonds O-H…O.     

Crystal and molecular structure of β-(N-benzoxazoline-2-thione) propionic acid and its salts

The crystal and molecular structures of β-(N-benzoxazoline-2-thione)propionic acid, its monoethanolammonium (NН₂(CH₂)₂OH) and ethylenediammonium (NН₂(CH₂)₂NH₂) salts are studied. In the salts the monoethyleneamine amine group participates in the deprotonation of one ethylenediamine–two β-(N-benzthiazolin-2-one)propionic acid molecules. The geometry of the molecules and intermolecular hydrogen and donor-acceptor bonds in crystals are analyzed. In the crystal structures weak interactions form a two-dimensional layer whose thickness corresponds to unit cell sizes.     

Stability of a vacuum arc discharge on surfaces of hot-rolled steels and its frequency characteristics

The stability of a vacuum arc discharge (VAD) with allowance made for the parameters of an external circuit and a deduced equation of the heterogeneous kinetics of elementary cathode spots (ECSs) in the group cathode spot with one-dimensional configuration is analyzed. It is theoretically and experimentally shown that a VAD with a rising voltage-current characteristic (VCC) is stable independently of the parameters of the external circuit. Stability conditions for a VAD with falling VCC are found.     

Effect of the cathode spots of a vacuum arc on the properties of the surface layer of structural materials

The application of vacuum-arc discharge provides great opportunities for metallic-surface cleaning and the development of products with the required functional surface properties. The effect of vacuumarc treatment on the roughness of the surface, its mechanical properties, and the structure and composition of the surface layer is studied. The processing and cleaning of the surface of steel samples by cathode spots of a vacuum-arc discharge form a structurally changed layer with a thickness of up to 10 μm and a microhardness exceeding the initial one by 1.4–1.5 times. The deposition of 20% solution of KOH and NaOH alkalis (substances which reduce the electronic work function of the scale surface) on the processed steel surface reduces the specific power inputs of vacuum-arc cleaning by a factor of 1.5–2.4. The depletion of the surface layer of low-grade steels by impurity elements enhances its anticorrosion properties.     

Brightening in the UV region of GSGG crystals after γ-irradiation

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 48, No. 1, pp. 124–127, January, 1988.