Structuring of polyacrylonitrile solutions

Mechanisms of orientation for the solutions of polyacrylonitrile synthesized under conditions of radical and anionic polymerization were studied. The effect of the fractal-matrix structuring agent developed by the AIRES foundation on the correlation parameters of the solution density and average squared fluctuation polarizability, which can be used to determine how the supramolecular structure changes by “self-orientation” and “induced orientation” mechanisms, was analyzed.     

Lie symmetries and exact solutions of nonlinear equations of heat conductivity with convection term

The Lie symmetries of nonlinear diffusion equations with convection term are completely described. The Lie ansatzes and exact solutions of a certain nonlinear generalization of the Murray equation are constructed. An example of the family of non-Lie solutions of the Murray equation is given.     

Two-Dimensional Excitons in Multiple GaN/AlN Monolayer Quantum Wells

JETP Letters - The decay kinetics of low-temperature exciton photoluminescence in a heterostructure with multiple GaN/AlN monolayer quantum wells, which is prepared by molecular beam epitaxy, is...     

Manifestation of oxygen desorption in photoluminescence spectra of ZnO

The influence of oxygen desorption on the photoluminescence of zinc oxide has been investigated. Photodesorption and thermal desorption of oxygen have been controlled using mass spectrometry. It has been found that the removal of oxygen from the ZnO surface leads to a manifold increase in the exciton photoluminescence intensity. The process has a reversible character. The mechanism of increase in the exciton luminescence intensity of ZnO during the oxygen desorption has been discussed.     

Effect of conditions of thermal treatment on the porous structure of an aluminum oxide-containing nanofibrous aerogel

The effect the conditions of thermal treatment have on a specific surface and the number of primary adsorption centers is studied. The relationship between changing adsorption characteristics and changes in the structure of nanofibrous aluminum oxide is considered.     

Optical and electrical properties of GaN: Si-based microstructures with a wide range of doping levels

The optical and electrical properties of silicon-doped epitaxial gallium nitride layers grown on sapphire have been studied. The studies have been performed over a wide range of silicon concentrations on each side of the Mott transition. The critical concentrations of Si atoms corresponding to the formation of an impurity band in gallium nitride (～2.5 × 10¹⁸ cm^?3) and to the overlap of the impurity band with the conduction band (～2 × 10¹⁹ cm^?3) have been refined. The maximum of the photoluminescence spectrum shifts nonmonotonically with increasing doping level. This shift is determined by two factors: (1) an increase in the exchange interaction leading to a decrease in the energy gap width and (2) a change in the radiation mechanism as the donor concentration increases. The temperature dependence of the exciton luminescence with participating optical phonons has been studied. The energies of phonon-plasmon modes in GaN: Si layers with different silicon concentrations have been measured using Raman spectroscopy.     

On the role of strong turbulence in low-pressure rf discharges in a magnetic field

The results of an experimental and theoretical investigation of strong turbulence produced by an external rf field in the plasma of a beam-plasma discharge are presented. The modulation instability of a rf electric field, perpendicular to a constant magnetic field, in the frequency range between the lower-hybrid and ionic Langmuir frequencies, has been investigated. It is shown that the low-frequency fields can be used to control beam relaxation. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 9, 608–612 (10 November 1996)     

Conditional invariance of the nonlinear wave equation

Conditional invariance of the nonlinear wave equation with respect to the infinite-dimensional, the conformai, and the Poincaré algebras is established.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 3, pp. 394–399, March, 1991.     

Optical sectioning in wide-field microscopy obtained by dynamic structured light illumination and detection based on a smart pixel detector array

Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing.