Advantage of heat insulation made of materials with natural porosity

Various heat insulation materials produced at home and abroad are compared. The advantage of using natural nano-structured materials is substantiated. Translated from Novye Ogneupory, No. 7, pp. 41–44, July 2008.     

γ-Absorption express analysis of the moisture content of coal concentrate in coke production

Coal concentrate with minimum moisture content is used for coke production in metallurgy. At various enterprises, the moisture content is determined by weighing [1]. However, this method is slow and is undertaken in the laboratory. To reduce the loss of production, accelerated monitoring of the moisture content in industrial conditions is required.     

Study of medium-cement concrete based on mixed Chamotte-periclase chromite filler

The possibility is demonstrated of using an addition of periclase-chromite filler (PCF) prepared from PCF grade broken material articles in medium-cement concrete with chamotte filler. The effect of this addition on cement hardening duration, strength and heat resistance is considered. Translated from Novye Ogneupory, No. 8, pp. 42–46, August 2008.     

Reproducibility of plastic measurements: The need to modify State Standard GOST 1186-87

A very important characteristic of coking coal is its clinkering ability, i.e., its ability to form a nonvolatile solid residue, consisting of disparate grains, on heating in specific conditions. The clinkering ability of the coal is determined by the properties of its plastic mass. Various methods may be used to evaluate the plastic-ductile properties of the coal. However, since the 1930s, the main method used to evaluate the clinkering properties of coal, within the nations of the former Soviet Union, has been the Sapozhnikov-Bazilevich plastometric method, because it provides more information than competing approaches. For the same reason, the thickness of the plastic layer, which is one of the parameters determined by this method, is used for coal classification in State Standard GOST 25543-88 (Lignite, Coal, and Anthracite: Genetic and TEchnological Classification) and its Ukrainian counterpart DSTU 3472-96 (Lignite, Coal, and Anthracite: Classification). This explains the strict requirements on the accuracy and reliability of the plastometric characteristics.     

Introduction of microdoses of germanium and indium dopants into the bulk and surface layers of semiconductor materials

A technique is proposed for introducing microdoses (10^?5–10^?10 g) of germanium and indium metals into semiconductor compounds by coulometric titration in a solid electrolyte cell. The solid electrolytes that are reversible with respect to germanium cations (the GeSe-GeI₂ system containing 5 mol % GeI₂) and indium cations (the InCl₃-MgCl₂ system containing 15 mol % MgCl₂, the InCl₃-CdCl₂ system containing 1.5 mol % CdCl₂, and the In₂S₃-InCl₃ system containing 5 mol % InCl₃) are chosen, and their electric transport properties are characterized. The optimum conditions for electrochemical doping (temperature, current density), under which the current efficiency reaches 90–100%, are determined. The doping with germanium and indium is performed for nonstoichiometric compounds, such as lead monotelluride, indium sulfide, and ternary chalcogenide spinel Cd_{1 ± δ}Cr₂Se₄. The doping efficiency is controlled by measuring the electromotive force of the corresponding electrochemical cells and the Hall effect, as well as using the electrical conductivity method. The solid electrolytes that are reversible with respect to indium are used to determine the standard Gibbs energies of formation of a number of indium-containing semiconductors.     

Influence of protein and lipid concentration of the test lubricant on the wear of ultra high molecular weight polyethylene

To gain a better understanding of the ultra-high molecular weight polyethylene (UHMWPE) wear mechanism in the physiological environment, the effects of protein and lipid constituents of synovial fluid on the specific wear rate of UHMWPE were examined experimentally. The multidirectional sliding pin-on-plate wear tester was employed to simulate the simplified sliding condition of hip joint prostheses. Bovine serum γ-globulin and synthetic l--DPPC were used as model protein and lipid constituents of synovia, respectively. Results of the wear test indicated that the UHMWPE wear rate primarily depended on the protein concentration of the test lubricant. Lipids acted as a boundary lubricant and reduced polyethylene wear in the low protein lubricants. However, the polyethylene wear rate increased with increasing lipid concentrations if the protein concentration was within the physiological level. Increased interactions between protein and lipid molecules and lipid diffusion to polyethylene surface might be responsible for the increased wear.     

Generalized ACE Constrained Progressive Edge-Growth LDPC Code Design

In this letter, we propose a generalization of the progressive edge-growth (PEG) algorithm with the aim of designing LDPC code graphs with substantially improved approximated cycle extrinsic message degree (ACE) properties. The proposed realization of generalized PEG algorithm outperforms original PEG algorithm and its subsequent modification proposed by Xiao and Banihashemi.