Local structure of divalent silver complexes in fluorite crystals as seen by EPR method

The analytical expressions for spin-Hamiltonian parameters of Jahn-Teller paramagnetic centres [AgF2F6]6- in fluorite crystals are deduced. Comparison with the experimental EPR data for CdF2, CaF2 and SrF2 yields information about the local structure of centres [AgF2F6]6-. It is found that two Ag2+-F- bonds of the centre (along the 〈111〉 direction) are shorter than the rest six bonds by factor 1.1. Euler angles of six non-axial fluorines are almost the same as those in the undistorted fluorite structure. © Springer-Verlag 1998 Printed in Austria

Subsidence deformations of the foundations of hydraulic structures

One of the most important tasks in designing and constructing reclamation network structures on loess subsidence soils is to ensure their long-term trouble-free operation. The improvement of methods for the design of hydraulic structures on subsidence foundations requires further study of very complex physical processes occurring in the foundations of structures during their construction and operation. This is confirmed by the fact that even if all the requirements and recommendations of regulatory documents for the design of irrigation systems on subsiding soils are observed, the deformations of the foundations of structures often significantly exceed the calculated ones, which can cause a loss of serviceability of irrigation structures. This determines the need for further study peculiarities of interaction of irrigation structures with their subsidence bases. This article is devoted to this problem, in particular, to the study of the influence of stress redistribution in wetted subsidence foundations of hydraulic structures on the stressed state of their elements and the stress-strain state of loess subsidence foundations on the models of float bets of hydraulic structures in the Karshi steppe

Calculation of concentration of aerosol particles around a slot sampler

A mathematical model and numerical procedure are proposed for investigation of aspiration efficiency and the particle concentration field around a slot sampler in a moving gas. A potential-flow model for the carrier gas and a Lagrangian method for calculation of particle trajectories and concentration are employed. The particle concentration patterns around the slot and at the sampler inlet are studied. The dependence of the aspiration efficiency on the ratio of the wind and sampling velocities is analyzed. It is shown that the local aspiration efficiency calculated on the symmetry axis of the slot gives satisfactory approximation for the integral aspiration efficiency. © 2007 Elsevier Ltd. All rights reserved

Some Remarks on Combining Forms in English-Japanese Dictionaries

© 2016, Pleiades Publishing, Inc.Previously unknown isononylcalix[8]arene was synthesized from commercially available isononylphenol. The properties of the product (solubility, extraction ability, tendency to aggregation) were compared with those of the known tert-butylcalix[8]arene. The extraction of 137Cs, 99mTc, and 241Am from alkaline carbonate solutions with solutions of p-alkylcalix[8]arenes (alkyl = tert-butyl, isononyl) in tetrachloroethylene was studied. The dependence of the distribution ratios on pH of the aqueous phase in the interval from 11 to 13.9 and on the nature of functional groups in the calixarene core was determined. The composition of extractable solvates of cesium and americium with calix[8]arenes was found. Calix[8]arenes extract cesium from alkaline solutions more efficiently than p-tert-butylphenol, their nonmacrocyclic analog, does. tert-Butylcalix[8]arene exhibits the highest performance, which may be due to formation of aggregates 5.7 ± 0.8 nm in diameter in the organic phase at pH 13.5 of the aqueous phase. The isononyl derivative exists in the monomeric form (particle diameter 1.9 ± 0.5 nm)

Aerosol aspiration into a cylindrical sampler from a low-velocity downward flow and from calm air

The problem of aerosol aspiration into a two-dimensional cylindrical sampler from a low-velocity downward flow and from calm air is solved. A simple analytical model for the velocity field of the carrier medium in the vicinity of the sampler with allowance for the finite size of the input orifice is proposed. Parametric studies of the aspiration factor as a function of the Stokes number for different ratios of the free-stream and aspiration velocities and different gravity-induced sedimentation velocities for two positions of the sampler are performed. Sedimentation of particles on the lower side of the cylinder for the sampler with a downward-oriented orifice is discussed. © 2005 Springer Science+Business Media, Inc

Numerical adiabatic potentials of orthorhombic Jahn-Teller effects retrieved from ultrasound attenuation experiments. Application to the SrF2:Cr crystal

A methodology is worked out to retrieve the numerical values of all the main parameters of the six-dimensional adiabatic potential energy surface (APES) of a polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from ultrasound experiments. The method is based on a verified assumption that ultrasound attenuation and speed encounter anomalies when the direction of propa- gation and polarization of its wave of strain coincides with the characteristic directions of symmetry breaking in the JTE. For the SrF2:Cr crystal, employed as a basic example, we observed anomaly peaks in the temperature dependence of attenuation of ultrasound at frequencies of 50-160 MHz in the temperature interval of 40-60 K for the wave propagating along the [110] direction, for both the longitudinal and shear modes, the latter with two polarizations along the [001] and [110] axes, respectively. We show that these anomalies are due to the ultrasound relaxation by the system of non-interacting Cr2+ JT centers with orthorhombic local distortions. The interpretation of the ex- perimental findings is based on the T2g (eg +t2g) JTE problem including the linear and quadratic terms of vibronic interactions in the Hamiltonian and the same-symmetry modes reduced to one interaction mode. Combining the experimental results with a theoretical analysis we show that on the complicated six-dimensional APES of this system with three tetragonal, four trigonal, and six orthorhombic extrema points, the latter are global minima, while the former are saddle points, and we estimate numerically all the main parameters of this surface, including the linear and quadratic vibronic coupling constants, the primary force constants, the coordinates of all the extrema points and their energies, the energy barrier between the orthorhombic minima, and the tunneling splitting of the ground vibrational states.Comment: 8 pages, 3 figure

Dependence of the wetting rate of the loess base on the moisture conditions

The increasing demand for improved irrigation systems in the world requires a more comprehensive and widespread study of the reliability and safety of hydraulic structures. In this regard, increasing the reliability during the operation of hydraulic structures of irrigation systems, especially on collapsible soils, is very important because loess subsidence soils are widespread globally, a significant part of loess rocks are also found in Central Asia, including the Republic of Uzbekistan. This article discusses the study of the features of the joint work of full-scale irrigation structures with their loess subsidence bases and the intense - deformative state of subsidence foundations during their joint work with hydraulic structures on irrigation canals of the Kashkadarya region

A numerical study of calm air sampling with a blunt sampler

The performance of an idealized spherical sampler facing both vertically upwards and downwards in calm air is studied numerically. To describe the air flow around the sampler, both potential and viscous flow models have been adopted. The equations of particle motion are then solved to calculate the aspiration efficiency. The dependence of the aspiration efficiency upon the various parameters of importance in calm air sampling are investigated and compared where possible with the experimental work of Su and Vincent (2003, 2004a, b). It is found that in the case of upwards sampling the bluntness of the sampler only has a significant effect upon aspiration for large sampling velocities, values that would not generally be physically realistic. In the case of downwards sampling an important non-dimensional quantity, B 2RC, is identified, where B represents the sampler bluntness and RC represents the gravitational effects. This quantity determines the physical conditions for which aspiration will not occur and also the limiting values of the aspiration efficiency when aspiration does occur. In the case of low sampling velocities a difference is noted between experimental and numerical results for aspiration efficiency raising the need for more experimental data in this area. For both upwards and downwards sampling the semi-empirical models of Su and Vincent (2004b) have been modified to account for the information gained from the study. This is particularly important in the downwards sampling case where the modified model is found to agree particularly well with the results obtained. Copyright © American Association for Aerosol Research

The fully Lagrangian approach to the analysis of particle/droplet dynamics: Implementation into ansys fluent and application to gasoline sprays

The fully Lagrangian approach (FLA) to the calculation of teh number density of inertial partucles in dilute gas-particles flows was incorporated into teh CFD code ANSYS Flunet. The new verion of ANSYS Fluent was applied to moedling dilute gas-particle flow around a cylinder and liquid droplets in a gasoline fuel spray. In a steady-state case, thre predictions of the FLA for the flow around a cylinder and those based on teh equilibrium Eulerian method (EE) are almost the same for small Stokes number (Stk) and small Reynolds number (Re). FLA predicts higher values of the gradients of particle number densities in front of the cylinder compared with the ones predicted by the EE for larger values of Stk and Re. Application of FLA to a direct injection gasoline fuel spray has concentrated on the computation of the number densities of droplets. Results revelaed good agreement between the numerical simulation and exeperimental data