Effect of preliminary radiation-oxidation treatment on electrophysical properties of zirconium

The effect of preliminary radiation-oxidation treatment on the current density and on the current-voltage characteristic of zirconium is studied. The contribution of the preliminary radiation-oxidation treatment to the change in the electrophysical characteristics is determined in heat and radiation-and-heat tests of zirconium in contact with water.     

Subunit stoichiometry of a core conduction element in a cloned epithelial amiloride-sensitive Na+ channel

The molecular composition of a core conduction element formed by the alpha-subunit of cloned epithelial Na+ channels (ENaC) was studied in planar lipid bilayers. Two pairs of in vitro translated proteins were employed in combinatorial experiments: 1) wild-type (WT) and an N-terminally truncated alphaDeltaN-rENaC that displays accelerated kinetics (tauo = 32 +/- 13 ms, tauc = 42 +/- 11 ms), as compared with the WT channel (tauc1 = 18 +/- 8 ms, tauc2 = 252 +/- 31 ms, and tauo = 157 +/- 43 ms); and 2) WT and an amiloride binding mutant, alphaDelta278-283-rENaC. The channels that formed in a alphaWT:alphaDeltaN mixture fell into two groups: one with tauo and tauc that corresponded to those exhibited by the alphaDeltaN-rENaC alone, and another with a double-exponentially distributed closed time and a single-exponentially distributed open time that corresponded to the alphaWT-rENaC alone. Five channel subtypes with distinct sensitivities to amiloride were found in a 1alphaWT:1alphaDelta278-283 protein mixture. Statistical analyses of the distributions of channel phenotypes observed for either set of the WT:mutant combinations suggest a tetrameric organization of alpha-subunits as a minimal model for the core conduction element in ENaCs.     

Interaction between multiply charged manganese nanoclusters and sulfur atoms in silicon

We have studied the interaction of manganese nanoclusters with sulfur atoms in silicon. The results indicate that both simultaneous and sequential codoping with manganese and sulfur has little effect on the electrical properties (resistivity, carrier mobility, and conductivity type) of silicon. There is no extrinsic photoconductivity in the IR spectral region, and the material has only a small positive magnetoresistance. According to electron paramagnetic resonance data, the material contains only atomic manganese. Sulfur atoms in the silicon lattice are assumed to facilitate the capture of doubly charged manganese interstitials (Mn²⁺) at negatively charged vacancies, resulting in the formation of a multicomponent impurity cluster of composition Si₂S²⁺Mn²⁻ in the silicon lattice throughout the crystal. The optimal thermal annealing conditions for the formation of such clusters are determined. The ability to produce Si₂S²⁺Mn²⁻ clusters with controlled concentration allows one to tailor the main fundamental parameters of silicon and opens up new possibilities for such materials in nano- and microelectronic device development.     

Heats of combustion of oil shale, bitumen, and their mixtures

The net calorific values of oil shale, tar oil, bitumen, and their mixtures were measured in a calorimetric bomb. It was found that mixtures of oil shale with tar oil (or bitumen) and coke exhibited the greatest net calorific values. A decrease in the ash content of these mixtures was found. The use of mixture components and ash residues as fuel and building material components, respectively, was proposed.     

Stabilizing mixture composition and properties in the serial production of cast-iron forgings

A balance model of replenishment permits stabilization of the composition of the sand-bentonite mixtures produced from local quartz sand and bentonite clay in the serial production of cast-iron forgings. A block diagram is presented for an automated system that is able to reduce the fluctuations in mixture composition and properties associated with frequent changes in the range of castings.     

Processing low-grade oxidized coal to produce effective carbon sorbents

High-porosity sorbents may be produced by carbonization of low-grade oxidized coal in the presence of alkali.     

Reflective light modulator based on epsilon-GaSe crystal

We report the results of investigating a low-voltage, polarization-insensitive, reflective-type modulator based on an epsilon-GaSe crystal and operated at the 1.960-eV line of a He-Ne laser. We demonstrate that the modulation in an Al-epsilon-GaSe-Cu device results mainly from the Franz-Keldysh effect. Relatively high speed and low operating voltage could make these modulators with Schottky-barrier contacts attractive devices in the red range of the spectrum.     

Optimal control of process of pyrolysis of paraffinic hydrocarbons C2-C4 and their mixtures

This paper describes the scheme that has been developed for the optimal control of the process of pyrolysis for different types of hydrocarbon feedstock in the four-flow pyrolysis furnace at the Sumgait Ethylene-Polyethylene plant; the scheme is based on the use of a complex parameter of the process, i.e., the pyrolysis intensity function. The algorithm for this control has been constructed. In the paper, the results of optimal control of the process of propane pyrolysis, ethane pyrolysis, and pyrolysis of ethane together with the butane-butylene fraction are presented in accordance with the scheme being developed using the intensity function that corresponds to each process. Optimal values of the intensity function were found from the results of calculations carried out using the mathematical model of each process. The extended expression for the intensity function has been formulated and, with its use, it is possible to control the process both in the case of the change in the flows of feedstock and steam and the change in the inlet temperature, as well as in the case of the change in the feedstock composition.     

Optimal assignment of dynamic priorities in queuing systems with two types of customers

We consider queuing systems with two types of customers. For such systems, we develop numerical procedures for computation of optimal dynamic priorities in the case of multiplicative priority functions. The optimality criterion is based on the total queue length for customers of both types. Our technique allows one to take into account waiting-time bounds. The optimization problem is formulated in the language of linear-fractional programming. To illustrate our technique, we present some numerical results at the end of the paper.