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First-principles calculations in the framework of the generalized gradient approximation together with Uon-site Coulomb corrections in the GGA + U approach to density functional theory (DFT) are performed to investigate the structural stability, magnetic order, and magnetocrystalline anisotropy of one-dimensional (1D) cobalt-oxide chains on Rh(553) step-surfaces. We found that the chains’ magnetic and structural stability strongly depends on the oxygen concentration, η. It is determined that there exist competing direct ferromagnetic and indirect antiferromagnetic exchange interactions in the doped-oxygen 1D linear chains, and in general, the oxygen doping stabilizes the antiferromagnetism. For pure Co linear chains and low oxygen concentrations, in which η ≤ 0.1 monolayers (ML), the ferromagnetic solution is the ground-state magnetic configuration. For η > 0.2 ML, the antiferromagnetic arrangement stabilizes through superexchange interactions. The strong influence regarding the oxygen-doping on the Co linear chains’ structural properties is evidenced when a small dimerization between the Co atoms at low O concentrations emerges. In contrast, dimerization in the Co chains is suppressed when the system is “oxygen-free” or η > 0.2 ML. The increase of oxygen concentration strengthens the pdhybridization between Co d-states and O p-states, leading to an electronic redistribution of the majority and minority bands of the Co d-states. Such a redistribution yields to the formation of more localized bands. A significant reduction of the local magnetic moment in the Co atoms is followed. The robustness of the DFT + U results is also discussed to some extent. Throughout a perturbative analysis, we also investigate the oxygen dependence on the magnetocrystalline anisotropy energy (MAE) for the Co-oxide chains, which ranges from 0.4 to 1.2 meV. Interestingly, magnetization directions canted to the wires’ direction or perpendicular to the Rh terrace are determined. Their origins are discussed in terms of the local contributions to the MAE.

Abstract: The present work is aimed at solving an urgent scientific problem of creation of high-strength and water-resistant dielectric glass-reinforced hot pressed glasses using bi- and polyfunctional epoxy amine binders and fiberglasses from alkalineless, quartz, and silica glasses, as well as their use in shipbuilding.

Abstract: The paper summarizes the experience of development and application of high-speed sliding bearings for centrifugal pumps of ship energy units, thermal electric stations, and nuclear power plants. The operation of sliding bearings involves superheated water to temperatures of 200°С and at sliding velocities of 20–40 m/s. Unlike metals, these sliding bearings need no additional oil lubrication. Two antifriction carbon plastics, namely, phenolic type FUT-B and new polyphenylene sulfide type UPFS, are discussed.

Abstract—Heat resistance of fiberglass plastics depends mostly on heat resistance of the polymer matrix (binder) and technological modes of production. Increasing the heat resistance and strength of electric insulation makes it possible to improve the properties of electric machines and prolong their working life. Hot pressing technology was developed and fiberglass plastic articles for electric insulation of parts of the ship propulsion complex (main and servicing diesel generators, turbo generators, electric motors) were manufactured. Exploitation modes were settled for electric insulation from different types of binders and reinforcing materials based on alkali-free, quartz, and siliceous high modulus and high strength glass fibers.

For the first time in Russia new antifriction carbon plastics based on super-thermoplastic matrix, made of polyheteroarylenes, have been developed by CRISM “Prometey”. These carbon plastics combine high strength and wear resistance at friction with lubricants made of water, including overheated up to 200°C, aggressive liquids, condensed gases, gasoline, oils, and in some cases without lubricants. The important advantage of new antifriction carbon plastics is the significant range of working temperatures from cryogenic (–240°C) up to 200°C. The paper describes successful experience of sliding bearings exploitation in centrifugal “hot” pumps of ship energy machines and vapor turbines.

Abstract: In order to study the effects of aging on the response of cells of the immune system to a proinflammatory (oxidative) agent, we examined the influence of peroxynitrite at a concentration of 30 μM on the structure of the surface layer of the cytoskeleton of thymocytes in rats of different ages. In the absence of a proinflammatory agent, we did not observe any substantial differences in morphological or topological features of thymocytes in 3- and 8-month animals. Atomic force microscopy revealed that peroxynitrite activated actin structure assembly in the cytoskeleton of thymocytes of 3-month animals whereas, in 8-month animals, it induced disassembly of cytoskeleton structures. Our data improve understanding of age-related differences in the response of the immune system to inflammatory processes in the body.

Efficient procedures were developed for N-deethylation of lappaconitine to give N(20)-deethyllappaconitine. Alkyl derivatives of N(20)-deethyllappaconitine, including labeled lappaconitine, and N(20)-acetoxy-N(20)-deethyllappaconitine were prepared for the first time. The assignments of the signals for the carbon atoms in the 13C NMR spectra of lappaconitine and related lappaconine were refined using 13C—13C 2D INADEQUATE and 2D 13C—1H correlation experiments.

Without Abstract:

GaN is a promising wide-band-gap semiconductor for the production of blue and UV emitters. The main problem for the advancement of GaN device technology is the absence of GaN substrates. SiC may be used as a substrate for GaN because of its reasonably low lattice mismatch (∼ 3%) and high electrical conductivity. We report here on the properties of GaN layers grown on SiC by metalorganic chemical vapor deposition (MOCVD). The GaN layer thicknesses ranged from 0.5 to 4 μm, and the growth rate was ∼ 2 μm h−1. Surface characteristics, crystal quality, optical, and electrical properties of GaN layers grown on SiC substrates were investigated. The first GaN light emitters formed on SiC substrates were fabricated.

The local and integral characteristics of flat MHD channels are studied with allowance for longitudinal and transverse edge effects and heterogeneities in the distributions of conductivity and stream velocity. An analysis is made of the effect of the finite dimensions of the insulating inserts in the longitudinal edge effect and of the modular construction of the side wall in the transverse edge effect on the output parameters of MHD channels. The solution of the problem is based on reduction of the initial quasilinear elliptical equation for the electrical potential with allowance for Ohm's law to an integral equation of the Fredholm type relative to the current density.

Abstract: We investigated silicon carbide (SiC) epitaxial layers grown by liquid phase epitaxy (LPE). The layers were grown on 6H-SiC and 4H-SiC well-oriented (0001) 35 mm diameter commercial wafers as well as on 6H-SiC Lely crystals. A few experiments were also done on off-axis 6H-SiC and 4H-SiC substrates. Layer thickness and growth rate ranged from 0.5 to 50 microns and 0.5 to 10 �m/h, respectively. Layers were investigated by x-ray diffraction, x-ray topography, and selective chemical etching in molten KOH. It was found that dislocation and micropipe density in LPE grown epitaxial layers were significantly reduced compared with the defect densities in the substrates.

Two large (dorsal mantle length 42.5 and 47.5 cm), mated spent females of circum-Antarctic bathypelagic cranchiid squid Galiteuthis glacialis were caught early in March 1992 at the surface of the ice hole in the western Weddell Sea over depths 1915-1920 m by the team of the U.S.A.-Russian Ice Station Weddell-I. The structure of the reproductive system of adult females is described for the first time in detail. Both were gelatinous, devoid of tentacles, with empty or almost empty stomachs. The empty spermatangia (sperm reservoirs of spermatophores) 30-35 mm in length were distributed in the mantle tissues parallel to the mantle surface and to each other in the dorso-anterior part of the mantle: 13 in one female, parallel to the body axis, and 20 in the other, parallel (13) or perpendicular (7) to the body axis. In the latter case, they represented probably two mating events. The spermatangia lay nearer to the inner than the outer mantle side and opened by a round window on the inner side; the skin with chromatophores above them remained intact. The spermatozoa had one flagellum and rod-like heads, length 5.0-5.3 μm, width 1.2-1.5 μm. The most characteristic features are: a very simple type of blood vessel branching making each micro-gonad currant-like, not grape-like; a very compact disposition of oviducal, nidamental glands and gill, forming a united complex located on both sides of the mantle cavity; and an ovary connected by mesentery along all its length with the continuation of the stomach from the caecum to the end of the gastrogenital ligament. Only immature degenerating trophoplasmatic oocytes, length 0.9-1.4, av. 1.0-1.2 mm, were contained in ovaries; only one mature egg (length 3.3 mm, width 2.4-2.5 mm) was found in each female. The absence of oocytes <0.9 mm and 1.5-3.2 mm indicates that the maturation of oocytes proceeds rather synchronously, one large portion of eggs (some tens of thousands) matures in a short time while others degenerate. The residual fecundity is assessed to be approximately 20,000 eggs. It is hypothesized that mating occurs shortly before spawning and that mature males do not undergo gelatinous degeneration and do not lose tentacles. Spermatophores are placed on the inner side of the female's mantle with the aid of the male's tentacles and/or arms (less probably by the penis), but the exact mode of implantation is unclear. Spawning probably occurs at depths of adult habitat (approx. 500±2500m), may be multiportional but short; the exhausted female loses neutral buoyancy, rises to the surface and dies. Rising to the surface after spawning is a common feature of females of many meso- and bathypelagic squids undergoing gelatinous degeneration during maturation (Onychoteuthidae, Gonatidae, Histio-teuthidae, Cranchiidae, etc.) and may explain the common occurrence of large deep-water squids in the stomachs of seabirds, including those incapable of diving, and marine mammals.

Abstract: 6H-SiC/GaN pn-heterostructures were grown by subsequent epitaxial growth of p-SiC by low temperature liquid phase epitaxy (LTLPE) and n-GaN by hydride vapor phase epitaxy (HVPE). For the first time, p-type epitaxial layers grown on 6H-SiC wafers were used as substrates for GaN HVPE growth. The GaN layers exhibit high crystal quality which was determined by x-ray diffraction. The full width at a half maximum (FWHM) for the ω-scan rocking curve for (0002) GaN reflection was ∼120 arcsec. The photoluminescence spectra for these films were dominated by band-edge emission. The FWHM of the edge PL peak at 361 nm was about 5 nm (80K).

1.A batch low-temperature rectification plant has been designed for obtaining methane of purity not less than 99.7 vol. %, and ethane of purity 99.5 vol. %.2.The operating conditions for obtaining these products on a pilot-plant scale have been selected.

Abstract: A study has been performed of the crystalline structure and optical characteristics of single crystals of gallium nitride (GaN). The crystals were grown from a gallium-based flux. X-ray structural analysis showed that the crystals have wurzite structure 2H-GaN. From their luminescence characteristics and optical absorption spectra the crystals are similar to 2H-GaN epitaxial layers described in the literature.

The effect of isobaric hyperoxia (99% oxygen, exposure for 3 h daily for 2 weeks) on the respiratory function of the blood was investigated in adult cats. An increase in the reticulocyte count (by 170%) and a decrease in the methemoglobin concentration in the blood (by 33%), in the affinity of hemoglobin for oxygen (by 13%), and in Hill's constant (by 16%) were found. After dialysis of hemoglobin solutions the differences in affinity between the control and experimental animals disappeared. No changes could be found in the number of hemoglobin fractions or in their mobility by electrophoresis on agar. It is concluded that the reaction of cat erythrocytes to hyperoxia is typical self-regulation, on the basis of which the affinity of the hemoglobin for oxygen falls in the presence of an excess of this gas.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.