The role of readily hydrolyzable polysaccharides of larch wood in manufacture of board materials

Role of readily hydrolyzable polysaccharides of larch wood in production of board materials is studied.     

Hydrolytic degradation and thermal stability of poly(naphthylimides) based on naphthalene-1,4,5,8-tetracarboxylic dianhydride and bis(naphthalic anhydrides)

The molecular properties of a number of new poly(naphthylimides) derived from naphthalene-1,4,5,8-tetracarboxylic dianhydride and bis(naphthalic anhydrides) have been studied. On the basis of hydrodynamic studies of the polymers at various stages of their thermal degradation in 96% H₂SO₄ and thermogravimetric measurements, the hydrolytic stability and thermooxidative resistance of the polymers have been compared. A correlation between the experimental data and the chemical structure of molecular chains has been established.     

Asymptotics in the Baum—Katz formula for random fields

In 1996, D. Deng established an analog of the Baum—Katz theorem on the convergence rate in the law of large numbers for multi-indexed random variables. The series describing the convergence rate depends, in a natural way, on the parameter characterizing the excess of the normalized sums over some level. In this paper, we find the precise asymptotics of the sum of this series with respect to the above-mentioned parameter. Thus, a generalization of a recent result due to A. Gut and A. Spataru is obtained.     

Influence of the prehistory of NaNbO3-Gd1/3NbO3 ceramics and single crystals on their dielectric properties

The dielectric properties of a ceramic and a single crystal of the same composition 0.9NaNbO₃-0.1Gd_1/3NbO₃ (NNG10) with different prehistories of the material are investigated in the low-and infralow-frequency ranges. It is revealed that the dielectric aging of the material based on the NaNbO₃ antiferroelectric with a smeared phase transition differs in character from similar phenomena observed in relaxor ferroelectrics.     

Quadratic differentials in problems of the product of inner radii of nonoverlapping domains

We study applications of the theory of quadratic differentials to the solution of new extremal problems of nonoverlapping domains with free poles on rays and generalize known results to a certain class of open sets. __________ Translated from Neliniini Kolyvannya, Vol. 10, No. 4, pp. 435–442, October–December, 2007.     

Surface morphology of electrolytic deposits of vanadium, cobalt, and manganese oxides

The surface morphology of V₂O₅, Co₂O₃, and MnO₂ electroplated under different electrolysis conditions was studied. The nature of the electrocrystallization of these materials was suggested on the basis of the analysis results.     

Changes in the supramolecular structure of heat-resistant polyimide fibers in the course of thermal treatment

Changes in the supramolecular structure of heat-resistant fibers based on polyimide PM were studied by X-ray diffraction analysis and NMR spectroscopy.     

Adhesion of polyimide films to microelectronic article components

Reactions between polypyromellitamido acid and component materials of microelectronic articles were examined by thermogravimetric analysis. Modes of modification of the surfaces of semiconductor structures to be used in formation of a system of interconnections with polyimide as interlayer insulator to obtain a high adhesion between the layers via their chemical reactions.     

On the convergence rate and optimization of a numerical method with splitting of boundary conditions for the stokes system in a spherical layer in the axisymmetric case: Modification for thick layers

The convergence rate of a fast-converging second-order accurate iterative method with splitting of boundary conditions constructed by the authors for solving an axisymmetric Dirichlet boundary value problem for the Stokes system in a spherical gap is studied numerically. For R/r exceeding about 30, where r and R are the radii of the inner and outer boundary spheres, it is established that the convergence rate of the method is lower (and considerably lower for large R/r) than the convergence rate of its differential version. For this reason, a really simpler, more slowly converging modification of the original method is constructed on the differential level and a finite-element implementation of this modification is built. Numerical experiments have revealed that this modification has the same convergence rate as its differential counterpart for R/r of up to 5 × 10³. When the multigrid method is used to solve the split and auxiliary boundary value problems arising at iterations, the modification is more efficient than the original method starting from R/r ～ 30 and is considerably more efficient for large values of R/r. It is also established that the convergence rates of both methods depend little on the stretching coefficient η of circularly rectangular mesh cells in a range of η that is well sufficient for effective use of the multigrid method for arbitrary values of R/r smaller than ～ 5 × 10³.     

Simulation of structure formation in disperse systems

The main rules governing the redistribution of microparticles in disperse systems were revealed by computer simulation. These rules predetermine the character and properties of the structure being formed, which opens up the possibility to control the properties of disperse materials, including sorbents and catalysts based on high-dispersity solid phases.