Influence of Magnetic Field and Temperature on the Synthesis and Colloidal and Chemical Properties of Fe3O4

A magnetic field and temperature was shown to affect disperse composition, electrophoretic behavior, and aggregation stability of synthesized magnetite particles. When synthesis proceeds, a process of the nucleation of ultramicroscopic Fe₃O₄ particles prevails over a process of their aggregation. Here an electrostatic factor of stability of magnetite suspension plays an important role. An application of the magnetic field decreases the aggregation stability and increases the sedimentation rate of product particles.     

Heterogeneous-catalytic decomposition of ethylenediaminetetraacetic acid and its complexes with iron,nickel, and cobalt on carbon materials in nitrate media

Catalytic thermal destruction of ethylenediaminetetraacetic acid and its complexes with nickel, iron, and cobalt in nitrate solutions on carbon materials (activated unwoven material, sibunite, and BAU–A activated carbon) was studied. The activation energies of thermal destruction were calculated.     

Effect of density and disperse composition of solid particles on the structure of a developed fluidized bed

A method is described for the experimental study of the characteristics of the bubble phase in a developed fluidized bed in examples of disperse materials belonging to groups A and B in the well-known classification of Geldart [1], which distinguished four groups of fluidizable materials according to the densities and dimensions of the solid particles. The method developed makes it possible to determine the average and local characteristics of the phase of the bubbles in apparatus of arbitrary dimensions. Depending on whether the material belongs to group A or group B of the classification, the distributions are found of the bubbles in respect of their vertical dimensions and their velocities, as are also the relative numbers of occasions when agglomerates coalesce and form, and the relative times of contact between the inhomogeneities and a sensor in a flat fluidized bed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 71–76, September–October, 1987.     

Nonlinear deformation and stability of noncircular cylindrical shells under internal pressure and axial compression

Stability analysis of noncircular shells is performed with allowance for nonlinear subcritical deformation. Explicit expressions for the rigid displacements of elements of noncircular cylindrical shells are obtained and used to construct shape functions of an effective quadrilateral finite element of natural curvature. A finiteelement algorithm for solving problems of nonlinear deformation and stability of shells is developed. Stability problem of an elliptic cylindrical shell is considered. The effect of the ellipticity and subcritical nonlinear deformation of the shell on the critical load is studied. Results obtained are compared with available experimental data.     

The non-linear deformation and stability of elliptical cylindrical shells under transverse bending

A finite-element formulation of the solution of problems of the stability of non-circular cylindrical shells taking into account their bending moments and the non-linearity of their precritical stress-strain state in proposed. Explicit expressions for the displacements of the elements of non-circular cylindrical shells as rigid bodies are derived by integration of the equations obtained by equating the components of the linear strains to zero. These expressions are used to construct shape functions of an effective quadrilateral finite element of the natural curvature. An effective algorithm is developed for investigating the non-linear deformation and stability of the shells. The stability of a cylindrical shell of elliptical cross-section under transverse bending is investigated. The influence of the ellipticity and non-linearity of the deformation on the shell's stability is determined. The results of the analysis are compared with experimental data.     

Synthetic calcium aluminosilicates and their sorption properties with respect to Sr<Superscript>2+</Superscript> ions

Sorption characteristics of synthetic calcium aluminosilicates (CAS) obtained in the multicomponent CaCl₂–AlCl₃–KOH–SiO₂–H₂O system are presented. The isotherms of Sr²⁺ sorption on CAS from aqueous solutions containing no additional salts were measured for Sr²⁺ concentration from 0.5 to 11.1 mmol/L and solid to liquid phase ratio S: L = 1: 100. The maximum sorption capacity of synthetic CAS was determined, the phase distribution constants of Sr²⁺ ions at different S: L ratios were found. The recoveries of Sr²⁺ ions from solutions containing 0.01 mol/L Ca(NO₃)₂ and from a solution simulating water of the Mayak plant sewage pond No. 11 were determined.     

Synthesis and specific features of mesomorphic behavior of new polysubstituted triphenylenes

Previously unknown 2,3,6,7,10,11-hexakis(dodecyloxy)triphenylene and -(tetradecyloxy)triphenylene were synthesized. The structures of the synthesized compounds were proved by elemental analysis and spectral methods. Polymesomorphism was found for the first time and studied for substances of the hexaalkoxytriphenylene homologic series, as well as liotropic mesomorphism in a series of organic solvents.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1676–1681, August, 2004.     

Instrumental neutron activation determination of gold in mineral raw materials using a californium neutron source

A facility using a californium neutron source and a method for the neutron activation analysis of gold were developed. The sensitivity of the determination is 0.1 g/t. The sources of random and systematic errors have been studied. It has been concluded that in prospection and evaluation of gold ore deposits, the traditional test tube analysis for gold may be replaced with the developed method.     

Sorbents for Analytical Determination of Cesium-137 and Strontium-90 in Natural Objects

The problem of determination of small activities of cesium and strontium in natural waters can be successfully solved by as design of highly sensitive lowbackground devices as development of new efficient techniques of concentrating radionuclides from large volumes of natural waters. While the problem of cesium concentrating may be solved quite successfully by a number of sorbents,the strontium concentrating is rather complicated.