Processing of Rare-Earth Elements from Loparite

Distribution of REEs and Th in extraction from chloride solutions with primary carboxylic acids C₇-C₉, 2-ethylhexanoic acid, and a crude mixture of higher branched carboxylic acids was studied. Thorium can be separated by extraction with carboxylic acids. The decay products were recommended to be precipitated after extraction of REEs. The radioactivity of loparite processing products considerably decreases with time.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 77–79.Original Russian Text Copyright © 2005 by Lebedev, Rudenko.     

Investigation of Stress-Strain Relations of initially anisotropic metals under proportional and nonproportional loading

In plasticity theories–applied in practical calculations- are usually based on the assumption of materials isotropy. Commercially obtained structural metallic materials however are originally anisotropic due to various kinds of thermal and mechanical treatments. Aluminium, titanium and magnesium alloys are typical anisotropic structural materials. The wide application of these materials in different fields of engineering demands more accurate mechanical behaviour predictions for these alloys under various conditions of loadings. In the aper, a simple theory of plasticity for anisotropic metals is proposed which is based on the results of experimental investigations into elasto-plastic deformation of initially anisotropic aluminium alloys subjected to simple (proportional) loading as well as under loading along stress path with a corner.     

Use of GTÉ-65 gas turbine power units in the thermal configuration of steam-gas systems for the refitting of operating thermal electric power plants

Thermal configurations for condensation, district heating, and discharge steam-gas systems (PGU) based on the GTé-65 gas turbine power unit are described. A comparative multivariant analysis of their thermodynamic efficiency is made. Based on some representative examples, it is shown that steam-gas systems with the GTé-65 and boiler-utilizer units can be effectively used and installed in existing main buildings during technical refitting of operating thermal electric power plants. Translated from élektricheskie stantsii, No. 6, June 2008, pp. 15–25.     

Kinetics of the hydrotreatment of rapeseed oil fatty acid triglycerides under mild conditions

To establish principal regularities of the hydrotreatment of rapeseed oil fatty acid triglycerides (FATs), the kinetics of this process has been studied at temperatures of 300–380°C, contact times of 0.38–0.10 h, and a hydrogen pressure of 1.0 MPa in a flow fixed-bed reactor. The process is performed over nonsulfided nickel catalysts, which are of great practical interest for the production of green diesel. The kinetic scheme of the process with consideration for target products (alkanes) and all oxygen-containing by-products has been proposed. The quantitative estimate, which enables the prediction of the composition of products for other process conditions, has been obtained for the principal paths of the hydrotreatment of rapeseed oil FATs.     

On the relationship between radiation-stimulated photoluminescence and nitrogen atoms in p-4H-SiC

Photoluminescence (PL) appearing in p-4H-SiC upon its electron irradiation has been studied. A model that accounts for the dependence of the PL intensity on the irradiation dose is suggested. The conclusion is drawn that nitrogen–radiation defect donor–acceptor pairs are PL activators.     

Irradiation of 4<Emphasis Type="Italic">H</Emphasis>-SiC UV detectors with heavy ions

Ultraviolet (UV) photodetectors based on Schottky barriers to 4H-SiC are formed on lightly doped n-type epitaxial layers grown by the chemical vapor deposition method on commercial substrates. The diode structures are irradiated at 25°C by 167-MeV Xe ions with a mass of 131 amu at a fluence of 6 × 10⁹ cm^?2. Comparative studies of the optical and electrical properties of as-grown and irradiated structures with Schottky barriers are carried out in the temperature range 23–180°C. The specific features of changes in the photosensitivity and electrical characteristics of the detector structures are accounted for by the capture of photogenerated carriers into traps formed due to fluctuations of the conduction-band bottom and valence-band top, with subsequent thermal dissociation.     

Efficient photogeneration of charge carriers in silicon nanowires with a radial doping gradient

by performing electrodeless time-resolved microwave conductivity measurements, the efficiency of charge carrier generation, their mobility, and the decay kinetics on photoexcitation were studied in arrays of Si nanowires grown by the vapor-liquid-solid mechanism. Large enhancements in the magnitude of the photoconductance and charge carrier lifetime are found depending on the incorporation of impurities during the growth. They are explained by the internal electric field that builds up, due to higher doped sidewalls, as revealed by detailed analysis of the nanowire morphology and chemical composition.     

Study of the ice sublimation processEtude du processus de sublimation de la glaceUntersuchung des EissublimationsprozessesИccлeдoвaниe пpoцecca cyблимaции льдa

The basic transfer equations for evaporation of a solid body into vacuum are considered. Experimental results on ice sublimation with thermoradiative and conductive heat supply as well as on sublimation in drying processes and continuous sublimation process from a permeable plate are presented. These studies explain the peculiarities of the sublimation mechanism for different energy supplies and under periodic and continuous conditions of the process. With ice sublimation from a porous permeable plate near a surface, a stepwise change in temperature is observed at a distance of several lengths of the mean free path of vapour molecules.     

3D simulation of electrodynamics of a microwave low pressure discharge

The structure of microwave fields in a discharge chamber used for obtaining electrode microwave discharge is investigated. It is shown that 3D-simulation allows quantitatively determining the optimumal structural parts of the discharge chamber for discharge generation. The represented results of self-consistent simulation of the discharge in nitrogen and hydrogen at a pressure of 1 torr are qualitatively consistent with experimental results.