Mass Transfer in Free Convection Developing in a Magnetic Field

The interaction of a charged hydrated particle with an external magnetic field is analyzed under conditions of diffusion and convective mass transfer. A model of forming local space charge regions in the bulk of a solution is suggested. The model is used to study the feasibility of changing the velocity and redistribution of charged particles in an aqueous medium. The results of theoretical calculations are tested experimentally by quantitative estimation of the rate of the convective liquid flow developed in crossed electric and magnetic fields.     

Influence of the silver ions on the physicochemical properties of methyl methacrylate-methacrylic acid copolymer films

The effect of silver ions on the physicochemical properties of methyl methacrylate-methacrylic acid copolymer films, namely, film-forming properties and resistance to fluorine-containing plasma, acid etchers, and temperature, was studied by lithography, derivatography, atomic-force microscopy, and optical spectroscopy. The activation energies were calculated for thermal transformations in the copolymer with and without silver ion additions, when heated in air to 300°C.     

Copper containing photocatalyst based on F-TiO2 for hydroden production from water and water organic solution

Work is dedicated to preparation and research of copper-containing mixed oxides systems based on F-dopped titanium dioxide for photocatalytic hydrogen extraction from water and water-organic medium. F-TiO₂ was obtained by titanium isopropoxide hydrolysis over NH₄F. Copper was added to the system in two ways: impregnation of its salt solution and directly in the process of titanium dioxide synthesis. Composition and structure of obtained systems were studied, as well as their optical and photocatalytic properties in specified process. It was established that the photocatalyst modified by copper injection at material synthesis stage has maximum activity.     

Thermal lens spectrometry for the synthesis and study of nanocomposites on the basis of silver salts absorbed by a polyacrylate matrix

Thermal lens spectrometry is applied to determine the absorption of transparent nanocomposite materials, which are produced by the thermal decomposition of silver salts absorbed in the bulk of a polymethacrylate matrix. The high spatial resolution of determination, corresponding to the size of laser beams, makes it possible to evaluate the homogeneity for the distribution of coloration in the matrix. The advantages of thermal lens spectrometry over spectrophotometry include the weak effect of sample scattering on the results of its absorption determination and a higher sensitivity of determination, which may exceed that of spectrophotometry by one or two orders of magnitude. The possibility of achieving local syntheses of nanosized particles in the bulk of the matrix by virtue of the photoinduced decomposition of silver salts in initial polyacrylate materials is shown. Thermal lens experiments also allow the combination of the synthesis of silver nanoparticles and control of the absorbance for the prepared structural units.     

Study of sorption and catalytic activity of peat-based composition material in relation to organic pollutants in waters

The effect exerted by modifying iron(III) chloride additive on the sorption and catalytic activity of granulated iron-containing peat composition in removal of oxalic acid was studied depending on the conditions of the solution treatment (ozone, UV radiation, and hydrogen peroxide). The conditions for virtually complete absorption of oxalic acid from model solutions were chosen.     

Mixed problems for the string vibration equation with nonlocal conditions of the general form at the right endpoint and with an inhomogeneous condition at the left endpoint

We consider four mixed problems for the string vibration equation with zero initial conditions, with a Bitsadze–Samarskii boundary condition of the general form at the right endpoint, and with an inhomogeneous Neumann or Dirichlet condition at the left endpoint. We prove the uniqueness of a generalized solution (in the sense of Il’in) of these problems and obtain an analytic representation of these solutions. The solution of each of the problems is represented in the form of a linear combination of functions constructed from the problem data, and recursion formulas for the coefficients of this linear combination are obtained.     

Sensitive solid-state optical sensible materials for photothermal determination of trace metals

Methods of photothermal (thermal-lens) determination of iron and mercury on the basis of solid polymer matrices with immobilized reagents are developed. These methods combine selective and efficient preconcentration of trace elements to be analyzed on a transparent polymer matrix, the sensitivity of determination with the reliable and traceable photometric procedures and highly sensitive thermal-lens detection (enhanced in polymers compared to solutions). The advantage of this approach is in the use of sensitive organic reagents previously developed for spectrophotometry. In this study, transparent polymethacrylate matrices modified with copper dithizonate and 1,10-phenanthroline were applied to the determination of mercury(II) and iron(II), respectively.     

Experimental setup for ground-based measurements in preparing cosmic experiments to study nuclear planetology

An experimental laboratory setup combining various gamma spectrometers and neutron generators that is intended for operating at the experimental nuclear-planetology facility deployed at the Joint Institute for Nuclear Research (Dubna, Russia) in order to perform physical calibrations of active gamma and neutron spectrometers is described.