Radioactivity in technological NPP waste

Concentrations of radionuclides in liquid and solid technological waste of the South-Ukrainian Nuclear Power Plant were studied. It is shown that correlated variation in radionuclide content of all samples is observed. Simple relations are derived for evaluating concentrations of radionuclides from the data on the ⁶⁰Co and ¹³⁷Cs activities. Original Russian Text ? M.D. Bondar’kov, A.M. Maksimenko, I.N. Vishnevskii, V.A. Zheltonozhskii, M.V. Zheltonozhskaya, L.V. Sadovnikov, S.V. Il’ichev, V.V. Boyarishchev, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 2, pp. 279–282.     

Radon transform and kinetic equations in the tomographic representation

Statistical properties of classical random processes are considered in the tomographic representation. The Radon integral transform is used to construct the tomographic form of the kinetic equations. The relationship between the probability density on the phase space for classical systems and the tomographic probability distribution is elucidated. Examples of simple kinetic equations like the Liouville equations for one and many particles are studied in detail.     

Integrable equations for the model with <Emphasis Type="Italic">N</Emphasis> sources and <Emphasis Type="Italic">n</Emphasis>-1 modes

We consider simplified models of coupling charged matter to radiation resonance modes generalizing the well-known Jaynes-Cummings and Dicke models. We find that these new models are integrable for arbitrary numbers of dipole sources and resonance modes of the radiation field. We discuss the problem of explicitly diagonalizing the corresponding Hamiltonians.     

A special set of eigenvectors for the hyperbolic Sutherland systems

We construct the integrals of motion for Sutherland hyperbolic quantum systems of particles with internal degrees of freedom (su(n) spins) interacting with an external field of the Morse potential of an arbitrary strength τ ² . These systems are confined if certain constraints are imposed on τ, the pair coupling constant λ, and the number of particles. The ground state is described by a wave function of the Jastrow form.     

Atomic Displacements in the α–β Phase Transition in Ag 2 S and in Ag 2 S/Ag Heterostructure

Orientation relationships between low-temperature monoclinic semiconductor α-Ag2S acanthite and high-temperature body-centered β-Ag2S argentite are determined. It is shown that, in cubic argentite, possible distances between silver atoms are too small for the sites of the metal sublattice to be occupied by Ag atoms with probability equal to one. With regard to the possible arrangement of Ag atoms, it is shown that, during the “acanthite–argentite” transformation, the jump of a silver ion from site (e) of monoclinic acanthite to site (j) of cubic argentite is the most probable process. It is established that the acanthite–argentite transformation in Ag2S/Ag heteronanostructure is accompanied by the formation of a conductive channel of silver Ag and β-Ag2S argentite under the application of an external voltage. The on-to-off-state current ratio in the synthesized Ag2S/Ag heteronanostructure is approximately equal to 670. For the Ag2S/Ag heteronanostructure, the energy barrier for the hopping of an Ag+ ion from an atomic site of monoclinic acanthite to a site of cubic argentite is estimated.     

Argentite-Acanthite Transformation in Silver Sulfide as a Disorder-Order Transition

An alternative model has been proposed for the phase transition from cubic argentite ß-Ag₂S to monoclinic acanthite α-Ag₂S in silver sulfide as a disorder–order transition. It has been shown that, as the temperature decreases below the transition temperature T_trans, S atoms equiprobably occupying the sites of the body centered cubic (bcc) nonmetal sublattice of argentite are concentrated at four sites of the monoclinic nonmetal sublattice, whereas the other sites remain vacant. A disorder-order transition channel including three superstructure vectors of k₉ and k₄ stars has been determined. The distribution function of sulfur atoms in monoclinic acanthite α-Ag₂S has been calculated. It has been shown that displacements of sulfur atoms distort the bcc nonmetal sublattice of argentite, forming a monoclinic lattice, where silver atoms are spaced by quite large distances and occupy their crystallographic positions with a probability of 1. The region of allowed values of the long-range order parameters η₉ and η₄ for the model monoclinic ordered phase α-Ag₂S has been determined.

     

Estimating the filtration characteristics of reservoirs from data of nonstationary studies of horizontal wells

Regularization methods are used to construct computational algorithms for the interpretation of results from hydrodynamic studies of horizontal wells that provide estimates of the reservoir anisotropy, reservoir pressure, and the dependence of the in-place permeability on pressure. In contrast to graphic analytic methods, the proposed approach does not require the identification of flow regimes.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 2, pp. 109–114, March–April, 2005.     

Micro-Raman Spectroscopy of Nanostructured Silver Sulfide

Nanostructured silver sulfide powder with an average particle size of about 45 nm, an acanthite α-Ag₂S monoclinic structure (space group P2₁/c), and nonstoichiometric composition Ag_1.93S has been synthesized by the chemical deposition method. The silver sulfide nanopowder has been studied by Raman spectroscopy. According to the Raman scattering data, heating the nanopowder with high-power laser radiation in air leads to photoinduced decomposition of the Ag_1.93S nanopowder to give silver metal. The Raman spectrum of the silver sulfide nanopowder shows a series of bands in the low-frequency range from 90 to 260 cm^–1 associated with vibrations of silver atoms, Ag–S bonds, and symmetric Ag–S–Ag longitudinal modes. Raman spectroscopy confirmed an acanthite monoclinic structure of synthesized silver sulfide nanopowder.     

Kinetic consequences of displacement adsorption in heterogeneous catalysis

Kinetic analysis of the simple reaction scheme of the heterogeneously catalyzed reaction AB has been made for the classical Langmuir adsorption and the Ipateev displacement adsorption. It has been shown that the only kinetic consequence of displacement adsorption is the different physical meaning of the parameters of the rate equation. Its form remains the same for both adsorption modes. This conclusion seems to be general also for other reaction schemes.

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AB . , . . .

     

Gas-chromatographic determination of trace <Emphasis Type="Italic">S</Emphasis>-[2-(<Emphasis Type="Italic">N,N</Emphasis>)-diethylamino)ethyl]methylphosphonothioic acid in water

A procedure is proposed for the gas-chromatographic determination of S-[2-(N,N)-diethylamino) ethyl]methylphosphonothioic acid (monothiol) in water at a level of 5 × 10^?5%. The procedure is based on the extraction of monothiol from water by liquid-liquid extraction, treatment of the extract with isopropanol in the presence of AgNO₃ and with diazomethane to obtain O-isopropyl-O-methyl methylphosphonate, and the chromatographic detection of the derivative obtained with a flame-photometric detector. The relative error of determining monothiol in water does not exceed 35%; the time of analysis is 60 min.