On sets which are removable for quasiconformal space mappings

Siberian Mathematical Journal -     

Ferroelectric photonic crystals based on nanostructured lead zirconate titanate

The first results obtained in the synthesis of one-dimensional ferroelectric photonic crystals based on nanostructured lead zirconate titanate and porous silicon are reported. The samples synthesized are studied using linear reflection and second optical harmonic spectroscopy.     

Chemical Concept of Geodynamic Shocks in Coal Strata

A chemical concept of geodynamic shocks in coal strata, accompanied by ejection of coal dust and gas, is suggested.     

Bulk strain energy density in randomly reinforced polymer composites with antifriction dispersed additives

Bulk strain energy density was numerically simulated for epoxy-phenol-based composites randomly reinforced with short polyimide fibers, with antifriction dispersed polytetrafluoroethylene (PTFE) additives. A mathematical model was constructed using the notion of a stress concentration operator (fourth-rank tensor) that relates volume averaged, or external, stresses within a heterogeneous material with their local values within an individual heterogeneity. The simulation was based on a generalized singular approximation of random field theory used to solve a stochastic differential equation of equilibrium of an elastic medium. This approximation yields an explicit expression for stress concentration in a composite material. The explicit expression allows one to analyze the distribution of bulk strain energy density depending on the composition, structure, volume and mass fraction of heterogeneities, and on the type and value of applied load. We studied how the considered energy characteristic depends on the type of external mechanical loading and concentration of isotropic components in the model composites. It is shown that with the increasing concentration of polyimide fibers at a fixed concentration of PTFE inclusions, the bulk strain energy density values of all components decrease and approach each other independently of the type of external loading. The form of these dependences is nonlinear. A change in the mass fraction of dispersed PTFE inclusions in the model composites exerts little effect on local energy values of all components under any of the considered applied external loads.     

Changes in electrical and optical properties of polyimide films under the action of accelerated electrons

Changes in the structure and optical and electrical properties of Apical brand polyimide films under the action in air of accelerated electrons with an energy of 0.5 MeV and absorbed dose varied in the range 1–300 MGy were studied.     

IR spectrum of the closed form of indolinospironaphthooxazine

IR absorption spectra of indolinospironaphthooxazine (ISNO) are presented. The geometric structure and normal coordinates of the ISNO molecule have been calculated using a quantum mechanical DFT method. The IR spectrum of ISNO in its original spiro form has been interpreted for the first time. Four normal modes in the range 800–1200 cm^–1 with the largest amplitudes of C_spiro–O bond change are identified. The excited ISNO molecule spiro form may experience photoconversion to the merocyanine form through them.     

The theorem on convergence with a functional for integral functionals with p(x)- and p(x, u)-growth

We continue studying weak convergence for the integral functionals satisfying p(x)- and p(x, u)-growth conditions. We obtain the theorem on convergence with a functional and some results on the relation between integral functionals and their abstract lower semicontinuous extensions.     

The effect of composition and structure on dielectric characteristics of films based on poly(vinyl alcohol) cyano ether

The composition, bulk structure, and supramolecular structure of poly(vinyl alcohol) cyano ether are studied by the methods of IR and high-resolution NMR spectroscopy and by atomic force microscopy. According to the data on the parameter of blockiness (η = 1.03), this copolymer is characterized by a random structure; the content of residual acetate groups is below the detection level of the applied methods. When the films are formed by screen printing, owing to the high orientation of polymer in the direction perpendicular to the direction of the supporting plane, the dielectric permeability of the films is higher than that of the films prepared by film casting. Films with a thickness of 20–40 μm are prepared, and their dielectric permeability approaches 23.     

Intense shock waves in bubble media

Shock waves in bubble media are studied experimentally. Data are obtained on the structure, velocity of propagation, and pressure of shock waves incident on a solid boundary and reflected from it. The experimental data are compared with the results of calculation of shock wave parameters.     

Interactions between nanosecond laser radiation and a surface of single-crystal strontium titanate

Technical Physics - The formation of local structurally modified areas on the surface of single-crystal strontium titanate has been considered. To this end, the fields of elastic mechanical...