Effect of Heat Treatment of Molten Bi2O3 Containing 22 mol % SiO2 on the State of the Metastable δ*-Phase Forming during Solidification

Inorganic Materials - We have studied the effect of isothermal holding of a melt containing 78 mol % Bi2O3 and 22 mol % SiO2 and various melt cooling schedules on the morphology, microstructure,...     

Reconstruction of the parameters of a reflecting half-space

An inverse problem for a dielectric layer placed on a dielectric half-space is solved. Parameters of the layer and the half-space are reconstructed from the frequency dependence of the squared absolute value of the reflection coefficient known in a limited frequency interval.     

An Ultra-High-Speed Starter–Generator with a Magnetic Core of Amorphous Iron for Unmanned Aerial Vehicles

Results of research on an ultra-high-speed starter–generator with permanent magnets and tooth windings for unmanned aerial vehicles are presented. Technologies for manufacturing of a stator magnetic core of amorphous iron, as well as methods of selection of the number of pole pairs of an ultra-high-speed starter—generator, are studied, the advantages of amorphous iron are substantiated. A particular stage of the work is devoted to the problems of optimization of the slotted area of a starter–generator on the basis of the criterion of the presence of minimum losses in permanent magnets for eddy currents. To minimize these losses, a multicriterion optimization of the slotted area is performed using the genetic algorithms, as a result of which the losses were a quarter those of the initial variant. A cooling diagram of the synchronous machine in the structure of the turbojet engine is proposed. Thermal calculations are presented. A full-scale mockup with a capacity of 5 kW, rotation frequency of 60000 rpm, power density of 0.2 kg/kW, and coefficient of efficiency 96.4% was created to check the proposed design sequence, as well as to determine the efficiency of using amorphous iron. Initial tests of the experimental mockup backed up the theoretical conclusions and showed that the use of amorphous iron allows reducing the losses in the magnetic core of the stator by five to seven times.     

Processing sulfate viscose cellulose prepared using oxygen in bleaching

Conclusions -- Two lots of cellulose, from pine wood and from larch, have been developed; these were treated in the first stage of bleaching with oxygen in alkaline medium instead of by chlorination, under experimental conditions.-- From a preliminary evaluation, the process of viscose preparation and preparation of the viscose for spinning under experimental conditions took place without significant deviations from the accepted technological regime. Higher technological indices of the viscose from pine cellulose were noted.-- The process of spinning viscose fibre from experimental lots of viscose from larch wood and from pine took place in a stable fashion; no clogging of the spinnerets was observed.Translated from Khimicheskie Volokna, No. 5, pp. 17–19, September–October, 1990.     

Analysis of the possibilities to determine lunar soil characteristics with the help of bistatic radar

An opportunity of determining the lunar soil characteristics via bistatic radar involving high-power ground-based transmitters operating in meter and decameter wave ranges and receivers located aboard Moon satellite is analyzed. Direct and inverse problems concerning stratified soil sounding to a large depth, as well as algorithms for determining the regolith layer thickness, permittivity, radio wave absorption, and regolith and bedrock densities, are examined.     

Thermooxidative stability of celluloses prepared from leafy and from coniferous varieties of wood

Conclusions The thermooxidative stability of celluloses prepared from deciduous and evergreen varieties of wood has ben investigated by methods of thermal analysis.It has been found that deciduous celluloses are less stable to oxidation processes as compared with evergreen celluloses, since they have an increased content of low-molecular fractions.Translated from Khimicheskie Volokna, No. 5, pp. 48–49, September–October, 1986.     

An investigation on the influence of rotor geometry on axial forces in the magnetoelectric damper of a suspension system

The magnetoelectric-damper geometry and influence of mechanical parameters onthe axial forces and on the electromagnetic processes in the damper are investigated. An analytic method for determining the magnetoelectric-damper axial forces is developed, and bases are given for a rotor with projections designed for minimizing axial forces is proved. Magneto electric-damper three-dimensional computer modeling using the final-elements method was carried out to confirm the theoretical data.     

Space-based radar systems intended for subsurface sounding of Mars and Moon soils

Space-based radar systems intended for investigating the subsurface layers of Mars, Phobos, and Moon are discussed. The characteristics of domestic radar systems developed in preparing the space projects devoted to the study of Mars soils (Mars-96 mission), Phobos ground (Phobos 1 and 2 and Phobos-Grunt missions), and the Moon surface (Luna-Glob mission) are presented. The characteristics of a long-wave Mars advanced radar for subsurface and ionosphere sounding (MARSIS) (Mars Express project) and a long-wave shallow radar (ShaRad) system included in Mars Reconnaissance Orbiter, as well as the results of processing of radar measurement data, are presented.     

Tissue-Specific Knockdown of Genes of the Argonaute Family Modulates Lifespan and Radioresistance in Drosophila melanogaster

Small RNAs are essential to coordinate many cellular processes, including the regulation of gene expression patterns, the prevention of genomic instability, and the suppression of the mutagenic transposon activity. These processes determine the aging, longevity, and sensitivity of cells and an organism to stress factors (particularly, ionizing radiation). The biogenesis and activity of small RNAs are provided by proteins of the Argonaute family. These proteins participate in the processing of small RNA precursors and the formation of an RNA-induced silencing complex. However, the role of Argonaute proteins in regulating lifespan and radioresistance remains poorly explored. We studied the effect of knockdown of Argonaute genes (AGO1, AGO2, AGO3, piwi) in various tissues on the Drosophila melanogaster lifespan and survival after the γ-irradiation at a dose of 700 Gy. In most cases, these parameters are reduced or did not change significantly in flies with tissue-specific RNA interference. Surprisingly, piwi knockdown in both the fat body and the nervous system causes a lifespan increase. But changes in radioresistance depend on the tissue in which the gene was knocked out. In addition, analysis of changes in retrotransposon levels and expression of stress response genes allow us to determine associated molecular mechanisms.     

Luna-Glob project: Radio sounding of the lunar soil

The dielectric parameters of the lunar soil that has been obtained in the study of the available samples are presented. A method for the radio sounding of the lunar soil from a spacecraft orbit is proposed. The main parameters of the radar for the space experiments in the framework of the Luna-Glob project are presented.