Diffusional metallization of graphite powders

Summary It was established that coatings can be formed on graphite in powders of the impregnating metal and its halide. Carbides are formed in the surface layer during the chromium, titanium, molybdenum, and tungsten impregnation of graphite. The growth of the coating layer thickness obeys a parabolic law.     

Histochemical study of sodium nucleinate-activated peritoneal macrophages

The activity of various enzyme groups and the levels of protein and glycogen in the peritoneal macrophages of CBA mice treated intraperitoneally with sodium nucleinate were determined histochemically with the use of cytophotometry. A significant increase in the activity of the lysosomal enzymes, such as acid phosphatase and nonspecific esterases and an increase in the activity of lactate, malate, glutamate, alpha-glycerophosphate, and beta-hydroxybutyrate dehydrogenases. NAD.H- and NADF.H-diaphorases accompanied by an increase in the level of the total protein and glycogen were observed. Analysis of the changes was indicative of an increase in the inherent physiological metabolic and functional level under the effect of sodium nucleinate. It is suggested that the macrophage sub-populations with an increased metabolic activity appeared in the peritoneal exudate of the stimulated animals. Participation of the host low molecular DNA in the maintenance of the physiological level of th nonspecific antiinfectious resistance is suggested.     

Graded carrier concentration materials for thermoelectric coolers

We have optimized the compositions of p-and n-type graded thermoelectric materials based on solid solutions between bismuth and antimony chalcogenides with high thermoelectric efficiency in the temperature range 100–400 K. Czochralski-grown graded single crystals have been used to fabricate graded legs 2.5 mm in height and 1.4 × 1.4 mm² in cross-sectional area for different stages of thermoelectric coolers. Pilot thermoelectric modules have been fabricated using homogeneous and graded legs, and the maximum temperature difference across the modules has been measured from 100 to 300 K. The efficiency of the modules with graded legs is shown to exceed that of the modules with homogeneous legs, especially at low temperatures.     

Extruded materials for thermoelectric coolers

We have optimized the compositions of p-type thermoelectric materials based on solid solutions between bismuth and antimony tellurides with high thermoelectric figures of merit in different temperature ranges between 100 and 300 K. The materials have been prepared by extrusion and have been characterized by microstructural analysis. Their thermoelectric properties have been studied in the range 100–400 K.     

Structural and electrical properties of layered tetradymite-like compounds in the GeTe—Bi2Te3 and GeTe—Sb2Te3 systems

Analysis of the available crystallographic data shows that the GeTe-Bi₂Te₃ and GeTe-Sb₂Te₃ pseudobinary systems contain a wide variety of many-layered, long-period compounds belonging to the nGeTe · mBi₂Te₃ and nGeTe · mSb₂Te₃ homologous series. The Hall coefficient, thermoelectric power, and electrical conductivity of some of these compounds were measured over a wide temperature range. The temperature-dependent carrier mobility data suggest that both acoustic phonons and point defects contribute to the scattering of charge carriers. The lattice thermal conductivity of the many-layered, long-period compounds studied, κ_ph = 6–8 mW/(cm K), is notably lower than that of the constituent tellurides