An approach to numerical modeling of the dynamics of reacting gases in nozzles

An approach is proposed to computer simulation of gas-dynamic processes in chemically nonequilibrium flows in supersonic nozzles. An algorithm for the solution of the problem is developed. Convergence of iterative processes and stability of the linearized problem are investigated.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 58, pp. 89–95, 1986.     

Correlation between the substrate roughness and light loss for interference mirror coatings

The correlation between the parameters of multilayer mirror coatings used in ring laser gyroscopes with the roughness height of the substrate and top surface of mirror coating is investigated. A complex approach is applied to analysis of the roughness of substrates and mirror coatings, which is based on the use of atomic force microscopy and X-ray scattering. A correlation between the roughness of substrates and mirror coatings is established. In addition, the correlation between the scattering coefficient, reflectance, and transmittance of multilayer mirror coatings and the roughness of the substrates used is investigated.     

Particular artifacts of topographic images of dielectrics in atomic-force microscopy

Particular artifacts of atomic-force microscopy (AFM) images of dielectrics, which are related to the presence of a static charge on the surface, are described. Artificial climate control with the use of a TRACKPORE ROOM-02 climatic box during measurements makes it possible to remove the static charge, owing to which the quality of AFM images and reliability of measured metric surface characteristics increase. Comparative analysis of the surface roughness measured under conventional conditions of microscope operation (static charge is present on a dielectric surface) and under the conditions of controlled artificial climate (static charge is completely removed) is performed. It is established that, in the presence of a static charge on the surface, roughness measurements may yield both overestimated and underestimated values; the largest increase in error is observed in measurements of micro-and nanosized surface areas.     

Synthesis,Molecular, and Crystal Structure of a Complex of Pentacoordinated Zinc with Chloride Ions and Pyridine-2-Carbaldehyde Hemiacetal

The reaction between pyridine-2-carbaldehyde and zinc chloride in wet MeCN yielded a zinc chelate complex with hemiacetal formed in situ from the hydrated pyridine-2-carbaldehyde and the second molecule of pyridine-2-carbaldehyde. According to X-ray diffraction data, the pentacoordinated environment of the zinc ion is formed by two chlorine atoms and the N,N',O-tridentate ligand. In the crystal, molecules are combined into a 3D supramolecular framework due to the intermolecular hydrogen bonds O–H···Cl, C–H···Cl, and π–π stacking interactions between pyridine rings.     

The structure and spontaneous orientational order in surface layers of water-soluble methyl- and hydroxypropylmethyl cellulose films

The structure of the surface layers of thin films cast from water-soluble derivatives of cellulose—methyl cellulose and hydroxypropyl methylcellulose—has been studied by the methods of an oblique polarized beam and molecular hydrodynamics. It has been demonstrated that the molecular chains of the polymers under study are characterized by a high degree of order in surface film layers. The orientational order of molecular chains demonstrates a strong molecular mass dependence. This effect is associated with the concentration of terminal segments whose orientational order parameter relative to the film surface differs from the corresponding value of internal segments composing the molecular chain. The quantitative estimates of the orientational order parameter of terminal and internal segments have been performed.     

Controlled Formation of β-Si3N4 on Native Oxidized Silicon Wafers in Ammonia Flow

Crystallography Reports - The formation of β-Si3N4 for subsequent growth of AlGaN and GaN heterostructures of silicon wafers has been studied. It is established that the native oxide layer...