The application of the Mössbauer spectroscopy for the study of the contaminants in the double circuit water heat-carrier nuclear power plant

The iron containing corrosion products from water heat-carrier and deposits of the second circuit of the nuclear power plant were investigated by means of absorption Mössbauer spectroscopy. The nonstoichiometric magnetite and paramagnetic (superparamagnetic) iron oxide particles were found to be the main corrosion products. The fraction of the magnetically ordered phase varied in the range 0–100% depending on the location in the second circuit.     

Mössbauer study of hydrothermally-treated ferrosilica gels

Mössbauer spectroscopy and x-ray phase analysis have been used to examine the structural states and grain sizes of the iron-bearing phase in ferrosilica gels in the initial state and after hydrothermal treatment at 673 K. The component ratio has a substantial effect on the phase composition. The specific surface is also related to the phase composition.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 5, pp. 647–651, September–October, 1987.     

RNA—PROTEIN CROSSLINK AND RNA CHAIN BREAK FORMATION ON UV-IRRADIATION OF TOBACCO MOSAIC VIRUS

Abstract— The ability of UV-irradiation (254 nm) to induce formation of RNA-protein crosslinks in tobacco mosaic virus (TMV) particles have been studied by Cs₂SO₄ density gradient centrifugation, analytical centrifugation, nitrocellulose filter binding and two-dimensional peptide mapping. RNA-protein crosslinks were found to be formed on UV-irradiation of TMV, but the parallel process of UV-induced RNA chain breakage complicated their quantitation. Using speciall devised equations, the quantum yield of RNA-protein crosslink formation was found to be 0.65 × 10⁻⁵ and that of RNA chain break formation 0.95 × 10⁻⁵.     

Classical and Generalized Solutions of a Mixed Problem for a Nonhomogeneous Wave Equation

Doklady Mathematics - A.N. Krylov’s ideas concerning convergence acceleration for Fourier series are used to obtain explicit expressions for the classical solution of a mixed problem for a...     

Studies of concentration and temperature dependences of precipitation kinetics in iron-copper alloys using kinetic Monte Carlo and stochastic statistical simulations

The previously developed ab initio model and the kinetic Monte Carlo method (KMCM) are used to simulate precipitation in a number of iron-copper alloys with different copper concentrations x and temperatures T. The same simulations are also made using an improved version of the previously suggested stochastic statistical method (SSM). The results obtained enable us to make a number of general conclusions about the dependences of the decomposition kinetics in Fe-Cu alloys on x and T. We also show that the SSM usually describes the precipitation kinetics in good agreement with the KMCM, and using the SSM in conjunction with the KMCM allows extending the KMC simulations to the longer evolution times. The results of simulations seem to agree with available experimental data for Fe-Cu alloys within statistical errors of simulations and the scatter of experimental results. Comparison of simulation results with experiments for some multicomponent Fe-Cu-based alloys allows making certain conclusions about the influence of alloying elements in these alloys on the precipitation kinetics at different stages of evolution.     

Generalized Ginzburg-Landau functionals for studies of phase transformations between FCC,BCC, and HCP structures in metals and alloys

Generalized Ginzburg-Landau functionals describing transitions between bcc, fcc, and hcp structures are studied using four weakly nonuniform transformation parameters: three tensile strains along the principal crystallographic axes and a “phonon” parameter describing relative slip of close-packed planes. Several versions of transformation paths indicated for each of the three transformations considered, which appear to be the most realistic; explicit expressions for atomic displacements are given for each of these paths. It is shown that the gradient terms in these functionals can be explicitly expressed in terms of the dynamic matrix of the crystal on a transformation path; these dynamic matrices can be determined using interpolations of experimental data on phonon spectra between the initial and final phases. The results are used for estimating the characteristics of interphase boundaries between ferrite and cementite in steels. It is found that the width of such interfaces considerably exceeds the interatomic distance, while the estimated values of the gradient terms are in reasonable agreement with the available experimental data.     

Riesz Bases of Eigenfunctions of an Integral Operator with a Variable Limit of Integration

We prove a theorem on the Riesz basis property in the space L ₂[0,1] of the eigenfunctions and associated functions of an integral operator whose kernel possesses a derivative discontinuous on the line $t = 1 - x$ .     

Correlation between the morphological characteristics and extinction spectra of sodium nanoparticles and modification of nanoparticles through photoatomic emission

The morphological characteristics of ensembles of metal nanoparticles on transparent dielectric substrates have been studied by the methods of hole-burning and linear absorption spectroscopy. The size and shape of particles were changed under the exposure to the optical radiation that induced photodetachment of atoms and their photostimulated diffusion over the surface of nanoparticles. The correlation between holes burned in different absorption bands is explained by the morphological features of the island film. The relaxation times of individual modes of collective plasma oscillations and the shape parameters of particles modeled by three-axial ellipsoids have been determined.     

Comparative investigation of the effect of heat and optical radiation on the structure of island metal films by optical fluctuation microscopy

Variations in the structural parameters of island sodium films on the quartz surface, caused by heating or exposure to optical radiation, are investigated by the optical method proposed earlier. A correct scheme of processing the measured data is developed. It is shown that to determine the structure parameters, the measurements of both the mean values and fluctuations of transmission and reflection coefficients of the film and of their correlator are required. It is also demonstrated that under a number of assumptions, it is possible to determine the character of the process of evaporation of islands and to reveal the evolution of the distribution function by using the data of measurements. It was found experimentally that variations in the structural parameters of a film during its evaporation caused by heating of the substrate or irradiation by light can noticeably differ. This fact is explained by a difference in the mechanisms of action of heating and irradiation on an island.