The influence of the chemical composition of silicon nitride films on their thermal oxidation parameters

The thermal dry-oxygen oxidation of Si₃N₄ films prepared by the ammonolysis of monosilane was investigated. Multiple internal reflection and simple transmission spectroscopy at IR wavelengths were used to determine the chemical composition of the films. The decrease in the thickness of the Si₃N₄ films after each oxidation run was measured by an ellipsometric technique using a hollow quartz prism. The parameters of the parabolic equation for oxidation at 1100°C were calculated for films deposited in the temperature range 750–1100°C. It was found that the oxidation rate depended on the concentration of N—H bonds in the film material. The diffusion of oxygen through the overlying SiO₂ film was found to be the limiting step of the process. The activation energy of the process was 52 kcal mol^-1.     

Fusibility diagram of the BaAl2O4-Ba2SiO4-BaZrO3 system

Conclusions New types of cement were developed from the BaAl₂O₄-Ba₂SiO₄-BaZrO₃ system. The cements are characterized by high refractoriness (over 1800°C) and cold-crushing strength (up to 885 kgf/cm²) and a high content of BaO (up to 66%).A statistical method of extremum experiments was used to plot the fusibility diagram of this system. The analytically predicted data agree well with the measured quantities.Translated from Ogneupory, No. 3, pp. 48–50, March, 1978.     

High-intensive femtosecond singular pulses in Kerr dielectrics

The nonlinear dynamics of a high-power femtosecond singular pulse in Kerr media are analyzed numerically upon optically induced ionization. We examine the plasma inertia impact to stable propagation of optical vortices. Multifoci behavior of vortices in medium are revealed. Next we numerically demonstrate that inertial character of plasma formation provides a quasi-soliton regime of vortex propagation resistant to symmetry-breaking perturbation.     

Nutrition of boys aged 14-15 years from 2 regions of Moscow]

Representative sampling of boys (n-577) aged 14-15 years was used to study their nutrition structure. The results obtained have evidenced the atherogenic character of nutrition due to insufficient consumption of vegetable oils, complex carbohydrates, excessive consumption of animal fats and sugar. These data can be used as the basis of nutrition correction for prevention of such risk factors of atherosclerosis as arterial hypertension, excessive body mass, dyslipoproteinemia.