Ceramics from mining by-products and alumina production wastes

The possibility of obtaining chemically stable ceramics in plastic molding from pastes based on comprehensive use of mining by-products (plagioporphyry, quartz-biotite shale), alumina production wastes (red mud), and polymineral clay was demonstrated. The mechanism of enhancing paste sintering on addition of finely disperse grog-flux and increasing the alkali resistance of the material (to 95%) in molding of the crystalline hematite-anorthite-quartz system was examined. __________ Translated from Steklo i Keramika, No. 2, pp. 17–20, February, 2007.     

Cyclosporin A-sensitive release of Ca2+ from mitochondria in intact thymocytes

Release of Ca2+ from mitochondria into cytosol in intact thymocytes was studied using the fluorescent dye Fluo-3. It was shown that the release of Ca2+ induced by the dithiol cross-linking agent phenylarsine oxide or by uncoupler was strongly inhibited by cyclosporin A, a specific inhibitor of the permeability transition pore (PTP) in mitochondria. Oxidative stress sensitized the pore so even partial uncoupling caused rapid cyclosporin A-sensitive release of Ca2+. The experiments on digitonin-permeabilized cells confirmed that uncoupling induced opening of the PTP, which forms the major pathway for rapid release of Ca2+ from thymocyte mitochondria.     

Automated system of research in the field of experimental mechanics of materials

The article describes an automated system for scientific research Mekhanika devised at the Institute of the Strength of Materials, Academy of Sciences of the Ukraine; the system is suitable for almost complete automation of routine operations in data processing of mechanical experiments connected with the calculation of the state of stress and strain of the test specimen, presenting the results of the calculation in the form of tables and graphs, and with the calculation of the required mechanical characteristics of the material. In addition the system offers the user great possibilities in generalizing the results of experiments, constructing various analytical approximations of the obtained data. The results of experiments and calculations can be stored in a specialized data bank.Translated from Problemy Prochnosti, No. 3, pp. 71–79, March, 1993.     

Grain boundary effect on electron-beam-induced current in La3Ga5.5Ta0.5O14 crystal

La₃Ga_5.5Ta_0.5O₁₄ crystal recently attracted more attention due to its superior electromechanical properties and high Q × f product. We report that the first electron-beam-induced current experiment on La₃Ga_5.5Ta_0.5O₁₄ single crystal. This method is employed to study the effect of the crystal's grain boundary on the incident electron beam. The experimental results clearly show that when the electron beam scans over the grain boundary of the crystal, a fraction of the carriers recombine at the grain boundary and is unavailable for the current generation. This recombination rate will be enhanced when the electron beam was close to the boundary and cause a dip in the collected current. Although the crystal is an insulator, this effect still can be observed if the coating metal is proper to be chosen. It is also pointed out that the different diffusion lengths of the crystal might be due to the tilted grain boundary.     

Multipurpose electroslag remelting furnace for modern energy and heavy engineering industry

In 2011, a unique complex based on a multipurpose unit-type electroslag remelting (ESR) furnace is created to meet the demand for large high-quality solid and hollow billets for the products of power, atomic, petrochemical, and heavy machine engineering. This complex has modern low-frequency power supplies with a new control level that ensure a high homogeneity and quality of the billets and an increase in the engineering-and-economical performance of the production. A unique pilot ESR furnace is erected to adjust technological conditions and the main control system elements.     

Conversion of air mixture with ethanol and water vapors in nonequilibrium gas-discharge plasma

In search for an alternative fuel for internal combustion engines, we have studied the possibility of obtaining molecular hydrogen via the conversion of air mixture with ethanol and water vapors in a new plasma reactor. It is shown that, in agreement with experimental data, the H₂ concentration is a linear function of the discharge current and decreases with increasing gas flow rate in the interelectrode gap. It is established that the proposed approach provides higher molecular hydrogen concentrations as compared to those achieved with other methods.     

Modeling high-concentration L-band EDFA at high optical powersbased on inversion function

High-concentration erbium-doped fibers used in L-band erbium-doped fiber amplifier (EDFA) are known to experience additional losses due to effects of energy transfer between Er³⁺ ions and possibly quenchers (e.g., homogeneous and clustering-induced up-conversion, quenching, etc.). These interactions between Er³⁺ ions make modeling of inversion dynamics in L-band EDFA more complicated. We present a modeling approach for high-concentration doped fiber based on lumping of all complex phenomena of energy transfer in EDFA into a function of two variables hereafter referred to as the inversion function. The inversion function is evaluated for high optical powers (which constitutes a typical situation for fiber amplifiers) using a cluster expansion and assuming that upconversion is the leading loss mechanism. The modeling results show a close agreement with the measurement data for various input power conditions and inversion levels     

Stochastic approach to the modeling and optimization of thermal spray coating formation

Application of the stochastic process theory is proposed for the modeling and optimization of the thermal spray process (TSP). The advantages of the approach suggested are illustrated by estimation of the“integral” thermal conditions of TSP coating formation, as well as the formation characteristics of the first monolayer coating. Modeling results are in reasonable agreement with bond strength test data for the plasma-, arc-, and flame-spray processes as well as wear resistance data for arc-sprayed steel coatings.