Structure of a titanium-alloyed high-tin bronze obtained by the Osprey method

The titanium-alloyed bronzes with enhanced (14.5 and 15.5 wt %) tin content obtained by the Osprey method have been studied by the methods of optical, scanning, and transmission electron microscopy with the use of quantitative microanalysis in the initial state and after hot extrusion. These alloys have been employed as bronze matrices of multifilamentary superconducting Nb/Cu-Sn composites. An increase in the tin content in the bronze matrix makes it possible to enhance the critical current density of the multifilamentary composite owing to the improvement of the structure and composition of a superconducting Nb₃Sn compound that is formed upon diffusion annealing. It has been shown that the Osprey technology allows one to obtain bronzes with an enhanced Sn content and simultaneously to reduce the dendritic segregation characteristic of cast bronzes. The distribution of Sn and Ti in these alloys has been investigated. A more homogeneous structure in the initial state is characteristic of the alloy Cu-14.5Sn-0.24Ti (wt %). The increase in the tin content to 15.5 wt % leads to the formation of microregions of dendritic segregation with an (α + δ) eutectoid in the initial state, which slightly decreases plastic characteristics of this bronze.     

支持IP漫游的多跳接入组网设计及协议扩展

针对现有固定宽带有线、无线接入技术存在的不足,本文结合Ad hoc技术和移动IP技术,提出了一种支持IP漫游的多跳接入方式,包括组网设计及协议扩展。其组网方式为：边缘接入采用多跳Ad hoc技术,主干接入采用分层移动IPv6技术。多跳Ad hoc网络大大增加了网络的覆盖范围,减轻了网络铺设成本,且支持宽带接入;分层移动IPv6降低了域内切换的信令开销和时延。同时,对现有的分层移动IPv6协议进行扩展,实现了主干网络与边缘多跳网络的有机结合。移动用户不但能以较低的信令开销实现全局的IP漫游,还能保证进入同一MANET网络中的移动节点直接通信,减轻了主干网络的传输负担,也保证了突发情况下节点能通过边缘MANET网络保持链路畅通。     

Mechanical and thermomechanical properties of highly basic anion-exchange fibres based on polypropylene containing grafted-on polystyrene

Conclusion The dependence of the mechanical and thermomechanical properties of fibres from polypropylene containing grafted polystyrene and of the anion-exchange fibres based on them on the content of grafted polystyrene in the fibre has been examined.It has been shown that the observed decrease in strength and elastic modulus of the original polypropylene fibre on grafting polystyrene and subsequent polymer-analogous transformations of it is entirely caused by an increase in linear density of the fibres.The animated polystyrene grafted to the polypropylene ensures an increase in the softening point of the anion-exchange fibres of 80 to 100°C as compared with the softening point of the original polyproplene fibre.Translated from Khimicheskie Volokna, No. 4, pp. 28–30, July–August, 1985.     

Formation of active phases in MoVTeNb oxide catalysts for ammoxidation of propane

The method of drying, heat evaporation or spray drying, of the aqueous suspension of starting chemicals has a pronounced effect on the phase composition of the final MoVTeNb catalyst, which ultimately influences the catalytic properties in propane ammoxidation reaction. The sample synthesized by spray drying is active and selective; it contains two main crystalline phases, orthorhombic M1 and hexagonal M2. The activity of the sample prepared by heat evaporation is low. This sample does not contain the active M1 phase and consists of hexagonal M2, TeMo₅O₁₆, and Mo_5−x(V/Nb)_xO₁₄ phases. The different mechanisms of phase composition formation in the samples synthesized by heat evaporation or spray drying arise from the different chemical nature of corresponding solid precursors.     

Differentiated dietotherapy of patients with obesity and hyperuricemia

Asymptomatic hyperuricemia was recognized in 344 patients with obesity. The use of low-calorie diets led to a reduction in the body weight and made purine metabolism more normal. The correcting effect was most remarkable with the use of low-caloric diets with a low purine content. Inasmuch hyperuricemia of long standing plays an important role in the development of podarga, atherosclerosis, it is recommended that obese patients should be treated with the diets with a low content of food purines.     

Structure of Al-Ti-C master alloys

A binary Al-Ti master alloy of hyperperitectic composition, whose structural characteristics ensure high modifying efficiency, has been prepared by the aluminothermy method. The treatment of the alloy by low-frequency vibrations (LFVs) and its interaction with the carbon emitter of LFVs in the process of crystallization lead to the formation of a ternary Al-Ti-C alloy containing titanium aluminide Al₃Ti and titanium carbide TiC. The presence of these phases creates favorable conditions for the formation of solidification nuclei in the aluminum melt when using a ternary master alloy as a modifier. A comparison of the efficiency of the structure refinement when using experimental master alloys and the standard Al-Ti master alloy poured into a metallic chill mold has been performed.     

Relationship between zero-charge potentials,critical passivation potentials,and flat band potentials for transition metals of groups IV–VI of periodic table in neutral alcohol media

The possible relationship between the critical passivation potentials, zero-charge potentials, and flat band potentials for transition metals of groups IV–VI of the periodic table in a series of alcohol solvents; their adsorption on a metal surface results in the transition of the metal into the passive state upon a certain shift in the potential with respect to E _q = 0.     

Effect of Technetium on the Efficiency of Solid-Phase Isotope Exchange

Tritium-labeled hexadecane, glycine, and -aminocaproic acid were prepared in the presence of supported palladium catalysts (straight and impregnated with technetium). The degree of isotope exchange is strongly affected by the reaction conditions. In isotope exchange of gaseous tritium with hexadecane, the degree of exchange obtained with the technetium-impregnated catalysts exceeds that obtained with the monometallic catalysts. The nature of the synergism is discussed.