Modern Methods of Intensifying the Processes of Heat and Mass Transfer in Contact Reactors with a Packing

Theoretical Foundations of Chemical Engineering - Instrumental and technological methods of intensifying the processes of heat and mass transfer in the column reactors with a packing are...     

Characteristics of heat-insulating refractories produced by some foreign companies

Conclusions Studies were made of heat insulating aluminosilicate products produced by certain companies. The articles are divided into four groups. It is found that within the limits of any one group there is a substantial spread in the properties: strength, apparent density, and temperature of deformation.The main form of raw material for producing insulating products is kaolin, including beneficiated kaolin. Out of 22 specimens investigated eight contained no more than 0.64% Fe₂O₃, which is important for the service of the products in reducing atmospheres; the semiacid and kaolin products contained iron oxide varying in the range 1.0–1.5%.The use of pure kaolins and low-ash combustible additives in the production of insulating refractories contributes to the production of refractories with a low concentration of fusible impurities.Translated from Ogneupory, No. 8, pp. 57–59, August, 1972.     

Photoluminescence and Transmission Electron Microscopy Methods for Characterization of Super-Multiperiod A3B5 Quantum Well Structures

Semiconductors - Promising semiconductor devices, such as quantum-cascade lasers and similar to them heterostructures with multiple strongly-coupled quantum wells, may contain hundreds and even...     

Symmetry analysis of magnetic structures possible in TbNi2Si2-TbMn2Si2 solid solutions

TbNi₂Si₂-TbMn₂Si₂ solid solutions have been studied by neutron diffraction to reveal magnetic structures with wave vectors {k ₈} = μ(b ₁–b ₂) + b ₃/2 = 2π [(1–2μ)/2, (1 + 2μ)/2, 0]/a, {k ₁₃} = b ₃/2 = 2π(1/2, 1/2, 0)/a, and {k ₁₄} = 0. The method of calculation is described and the results of calculations are given for the basis functions of irreducible representations of the space group D _4h ¹⁷ (14/mmm) that are used for the most rational search for a real model of the magnetic structure of these solid solutions. The compositions of the magnetic representations for each of the above-mentioned wave vectors and the possible variants of the mutual orientation of atomic magnetic moments in the crystallographic positions in which the magnetically active atoms (Tb, Ni, Mn) are located have been determined.     

The structure and magnetic properties of a heat-resistant nickel-base alloy after a high-temperature deformation

The structure of a turbine blade made of the ChS-70V alloy has been studied after operation in an experimental regime at 880°C. A considerable change in the structural state of the alloy indicates the presence of an extremely high level of stresses in the material. During the operation, the magnetic susceptibility of the alloy increases by two orders of magnitude. The possible structure objects responsible for a change in the magnetic susceptibility are the complexes of superstructure intrinsic stacking faults inside the intermetallic phase.     

Density distribution at the detonation front of cylindrical charges of small diameter

A synchrotron radiation based technique is use to study the density distribution at the detonation front and its neighborhood for condensed explosives. Particular data are obtained on the structure of the detonation front in TNT, RDX, and an alloy of TNT with RDX; a comparison of the data with those obtained using different techniques confirms the correctness of the technique. It is concluded that adequate information on the structure of the chemical-reaction zone can be obtained for charges of small diameter. At the same time, it is shown that the Chapman-Jouguet parameters for such charges are far from their predicted values for an infinite medium. The results of the work, including those on the curvature of the detonation front in charges of small diameter, supplement the existing knowledge of the detonation transformation in condensed explosives. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 2, pp. 91–99, March–April, 2007.     

The influence of an In<Subscript>0.52</Subscript>Al<Subscript>0.48</Subscript>As transition layer design on the transport characteristics of a metamorphic high-electron-mobility transistor

We have used the atomic force microscopy and Hall effect measurements to study the influence of In_0.52Al_0.48As transition layer design on the electron mobility in the InAlAs/InGaAs/GaAs channel of a highelectron- mobility transistor (HEMT) with the metamorphic buffer. The optimum buffer layer favors suppression of the misfit dislocation threading into upper layers of the HEMT heterostructure and prevents development of the surface microrelief.     

Anisotropy of the Thermal Conductivity of Parahydrogen Crystals

The anisotropy of thermal conductivity of parahydrogen crystals has been observed for the first time. The thermal conductivity measurements have been made on samples of different diameters at the temperature range from 2 to 8 K.     

Granulometric Analysis of Powder Materials Used for Producing Samples by Method of Selective Laser Melting

Metallurgist - The paper discusses the aspects of granulometric and morphological analysis of powders used in the technology of selective laser melting. Studies have been carried out to obtain...