Crystal Structure of Monohydrate of γ-Modification of Rubidium Uranoniobate

The compound γ-RbNbUO₆·H₂O was prepared for the first time as single crystals, which were studied by X-ray diffraction. Crystal data: rhombic system, space group Pcab, a = 7.614(2), b = 11.219(2), c = 16.510(3) Å, Z = 8. The crystal structure is built from uranium-containing layers of the composition [NbUO₆] _2∝ ^δ? , infinite in two directions. The water molecules and rubidium atoms distributed over two randomly occupied positions are accommodated between the layers.     

Investigation of the Dynamics of Evaporation of Condensed Bodies on the Basis of the Law of Spectral‐Radiation Intensity of Particles

The fundamentals of radiation theory and the mechanism of evaporation of condensed bodies are presented. The distribution functions of particles of a body by energies and by the intensity of their transition from one energy level to another in the process of evaporation have been obtained based on the law of spectralradiation intensity of the body particles. The temperature dependence of the resulting vapor flow on the outer surface of a massive condensed body and a thin layer in equilibrium and nonequilibrium states, which, in the limit, transforms to the known Hertz–Knudsen formula, has been found.     

Magnetothermal Analysis of Nanocrystallization of Amorphous and Relaxations of Nanocrystalline Materials

For a few years it has been realized that nanocrystalline phases can be formed during crystallization of amorphous alloys annealed isothermally below the crystallization temperature of usual heating experiments. Data of this transformation monitored by the measurement of magnetic susceptibility are presented. A method using a magnetic balance with electronic stabilisation and combined computer facilities is applied. Constant heating and cooling rates as well as isothermal heat treatments are used. Magnetic measurements are able to detect the onset of the transformation of amorphous Ni-P alloys much earlier than was possible with differential scanning calorimetry. The transformation kinetics can be analyzed by means of the Avrami plot based on the Johnson-Mehl-Avrami equation.The kinetics of solid state reactions in the nanostructured material can be investigated similarly. Formation of a Ni-phase in a nanostructured Hf-Ni alloy could be detected in a very early stage, where calorimetric methods are not sensitive. Segregation phenomena could be detected from the experiments even after long time. The sensitivity of the applied method is not dependent on the heating rate as the sensitivity of scanning calorimetry is     

Analysis of clusters and uniformity of distribution of states of polarization on the Poincaré sphere

An analysis of the clusters and the uniformity of distribution of states of polarization on the surface of a Poincaré sphere generated by rotating wave plates is given. The analysis of clusters of the states of polarization is based on a spherical radial distribution function. For uniform analysis of the distribution, two methods are proposed. The first method is based on calculation of the correlation coefficient; the second method is based on calculation of the angles between pairs of the states of polarization on the Poincaré sphere. For polarization scramblers consisting of eight or more rotating wave plates, nonclustered and near-uniform distribution of states of polarization is obtained.     

Influence of Temperature‐Time Parameters of Heat Treatment on the Process of Planarization of the Surface Relief of Microelectron Structures

The authors consider the process of fusion of phosphorosilicate and borophosphorosilicate glasses in planarization of the surface of integrated microcircuits under the conditions of both isothermal and pulse heat treatment. An expression for calculating the angle of fusion of the relief step as a function of the concentration of doping impurities in a glass and the time and temperature of heat treatment is obtained.     

Brief Outline of the Metallurgy Department of Kunming Institute of Technology

The metallurgy department of Kunm-ing Institute of Technology,with its empha-sis on nonferrous metallurgy,is one of themajor academic and technical centres underthe China National Nonferrous Metals In-dustry Corporation(CNNC).The province of Yunnan,of whichKunming is the capital city,is very rich withresources of nonferrous metals,such as     

Measurement of the activity of individual subunits of single molecules of the tetrameric enzyme β-galactosidase

Escherichia coli β-galactosidase was incubated in the presence of the slow-release inhibitor D-galactal for 30 min at a concentration of 70 times its K(i). The sample was then diluted 20000-fold into buffer containing the fluorogenic substrate 9H-(1,3-dichloro-9,9-dimethylacridin-2-on-7-yl) β-D-galactoside, reducing the inhibitor concentration to K(i)/280. The sample was subjected to a capillary electrophoresis continuous flow single enzyme molecule assay. As the inhibitor dissociated while the enzyme traveled the length of the capillary, a fraction of molecules showed stepwise increases in activity. This was due to the activation of individual subunits within single molecules. The changes in activity can be largely explained in terms of each molecule containing subunits of indistinguishable activity.     

Inhomogeneity of Grain Boundaries of ZnO Varistor

The zinc oxide varistor with a low threshold voltage and large grain size was derived with ZnO crystalline seeds from a molten salt process The chemical composition and I-V characteristics of single grains and single grain boundaries were determined by means of energy dispersive spectrum (EDS) and microcontact measurement respectively. Temperatu re dependence of dielectric loss at various frequencies and voltage dependence of capacitance were carefully measured. Based on these experimental data. the barrier heights of giain boundaries are estimated to be 0.2. 0.5 and 0.6 eV respectively corresponding to thick, th in and direct contact grain boundaries. In addition. a computerized electrical circuit simufation is employed in simulating I-V characteristics of single grain boundary within ZnO varistor. By adjustjng parameters of resistor and diode, a general agreement between the measured data and simulated curves is achieved     

Modeling of the Process of Electric‐Discharge Sintering of Metal Powders

Consideration has been given to the process of electricdischarge sintering (EDS) of a powder fill in passing an electric current through it. The dependences for calculation of the heat release, the efficiency of an EDS unit, the resistance of a powder fill, and the temperature in the contact zone have been obtained. An algorithm for calculation of the technological parameters of the process of EDS has been given.     

The Establishment of National TC of Superconduction

National standardization technical committee of superconduction was established on Aug 26th, 2003. Tmittee contains 22 experts, of which the percentage of professors and researchers reaches up to 77.3%mention there are four academician consultants, Gan Zizhao, Zhao Zhongxian and Yang Guozhen fromAcademy of Sciences, and Zhou Lian from China Academy of Engineering. The four academicians had ed earlier in the 7th Academic Seminar of Superconduction in April that the high-tech superconduct…     

Modeling of Microimprinting of Bulk Metallic Glasses

A finite element analysis （FEA） model has been developed to analyze microimprinting of bulk metallic glasses （BMG） near the glass transition temperature （Tg）. The results reveal an approximately universal imprinting response for BMG, independent of surface feature length scale. The scale-independent nature of BMG imprinting derives from the flow characteristics of BMG in the temperature range above Tg. It also shows that the lubrication condition has a mild influence on BMG imprinting in the temperature range above Tg.     

A Study of the Spread Surface of Polymeric Dispersions of Eudragit®

The rheology of non-Newtonian fluid systems is complex. Their experimental study is difficult because of the existence of many dependent variables. In the present work, a mathematical equation is proposed to calculate the spread surface from a simple viscosimetric study in a theoretical way. It was determined for multiple parameters. The spread surface has to be marked because of its direct relation to the shear stress; this fact enabled us to connect one variable dependent on the compression deformation with another dependent on the shear deformation. At the same time, the viscoelastic phenomenon can be evidenced by applying this mathematical equation.     

Effect of addition of tin on the microstructure and machinability of α-brass

This study was aimed at developing lead-free brass alloys with the goal of substituting lead element with tin. For this purpose, lead-free alloys with tin were developed and the microstructure, hardness and machining behaviour of the Cu–30%Zn alloy was compared with Cu–30%Zn–x%Sn (x?= 1.2, 3.2, 5.4, 8, 11.4, 13.9, 17.4). The results showed that the addition of Sn to single-α phase brass led to the formation of duplex (α?+?β′) brass and then the formation of (β′?+?? ) brass both with increased hardness. In addition, the addition of Sn to Cu–30%Zn alloy led to the decrement of equivalent machining forces (F_m), surface roughness and also the promotion of chip fragmentation due to the formation of the β′ phase, which is an improvement in machinability.     

Specific Features of In-Service Failures of Parts of the Landing Gear of AN-124 “Ruslan” Aircrafts

We present the results of investigation of the axles of wheels of AN-124 Ruslan aircrafts after failures occurring either in service or in the process of resource testing. It is shown that, in service, the axles fail according to the intergranular mechanism. At the same time, in the course of stand tests, we observe fatigue fracture. On the basis of the analysis of the structure of landing gear and the results of investigation of external factors, we propose a model of formation and propagation of cracks in the axle of a wheel. We also propose several procedures aimed at the prevention of failures.     

Diameters of the Liquid–Liquid Coexistence Curves of Aqueous Solutions of Tetrahydrofuran

The diameters of the coexistence curves of aqueous solutions of tetrahydrofuran and two quasibinary, isotopically related mixtures near their lower consolute points are analyzed in terms of different composition variables including mole, mass, and volume fractions, using various possible definitions of the reduced temperature. A (1–) anomaly is observed for all choices of the temperature and concentration variables. In terms of mole fraction the diameters are free from a regular contribution as well as from a spurious 2 contribution arising from the inappropriate choice of the order parameter. The mass and volume fractions lead to an apparent symmetrization of the coexistence curve, but cause significant 2 contributions to the diameter that could mask the 1– anomaly. A reduced temperature that accounts for the presence of both upper and lower critical consolute points is found to be preferable, although the second critical point is 80 K away.     

Effect of the Nature of Fluid and Structure of β-Diketone on Supercritical Extraction of Metal β-Diketonate Complexes

Extraction of uranium with trifluoromethyl alkyl diketones differing in the length of the alkyl chain was studied. The size of the alkyl group only slightly affects the extraction. Extraction of complexes formed by uranyl nitrate with -diketones in pentafluoroethane (Freon-125) was studied. The complexes are efficiently extracted with both super- and subcritical Freon-125. In contrast to extraction of these complexes in supercritical CO₂, in extraction with Freon-125 the complexes do not decompose.     

Computerized Simulation of Structure of NaAIO_2 Melt

The structure of NaAlO_2 melt has been studied by computerized simulation using Monte Carlomethod.The radial distribution functions and Local structure of this melt are calculated.It has beenfound that NaAlO_2 melt contains ionic clusters formed by corner-sharing AlO_4 tetrahedra,sodiumions and xNa~+.yO~(2-) ionic clusters.