Thermal stability of nickel structure obtained by high-pressure torsion in liquid nitrogen

Using transmission electron microscopy and durometry, the structural evolution of commercially pure nickel (99.6%) under high-pressure torsion (HPT) in liquid nitrogen and subsequent annealings in the temperature range 100–400°C has been investigated. In this nickel, at cryogenic temperature, HPT gives rise to a nanocrystalline structure with the record high microhardness (6200 MPa) and average crystallite size ～80 nm. The obtained structure is stable at room temperature and possesses a relatively low thermal stability, since recrystallization occurs at lower temperatures than after conventional deformation or HPT at room temperature.     

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.     

铅锌尾矿重金属释放影响因素的探讨

铅锌尾矿废渣若不经过处理,会通过风蚀、径流对环境造成重金属污染,对尾矿废渣污染的研究一直是大家关注的方向。多年来,pH被证实是影响重金属释放的重要因素。本文通过实验,研究了浸提方法、pH和盐度对铅锌尾矿废渣重金属元素释放的影响。结果表明,Pb、Zn、Cd、As在pH值呈酸性和碱性时浸出率都较高,Cu、Ni则在pH值为碱性时浸出率更高,盐度对Pb的释放影响效果更为明显。     

Progress towards a methodology for high throughput 3D reconstruction of soot nanoparticles via electron tomography

The aim of this work is to make progress towards the development of 3D reconstruction as a legitimate alternative to traditional 2D characterization of soot. Time constraints are the greatest opposition to its implementation, as currently reconstruction of a single soot particle takes around 5–6 h to complete. As such, the accuracy and detail gains are currently insufficient to challenge 2D characterization of a representative sample (e.g. 200 particles). This work is a consideration of the optimization of the steps included within the computational reconstruction and manual segmentation of soot particles. Our optimal process reduced the time required by over 70% in comparison to a typical procedure, whilst producing models with no appreciable decrease in quality.     

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.     

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.