Synthesis of 1,4-Dihydropyrano[2,3-<Emphasis Type="Italic">c</Emphasis>]pyrazole Derivatives

In reaction of 2-(2-thienyl)- and 2-(2-furyl)acrylonitriles with 3-methyl-1-phenyl-5-pyrazolone in the presence of basic catalysts 4-thienyl- and 4-furyl derivatives of 3,5-dimethyl-1,7-diphenyl-4,8-dihydropyrano-[2,3-c, 5,6-c]dipyrazole were obtained.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 756–758.Original Russian Text Copyright © 2005 by Vasyun’kina, Bykova, Plotkin, Ramsh.     

Action-type axiomatizable classes of group representations

The paper adjoins the work of B. I. Plotkin and S. M. Vovsi, Varieties of Representations of Groups (Zinatne, Riga (1983)), and turns out to be, in a sense, its continuation. In the former, the varieties of representations have been considered. As a matter of fact, the varieties under consideration are action-type varieties. This paper studies other classes of representations, axiomatizable in a special action-type logic. __________ Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 2, pp. 73–85, 2005.     

Study of the structural and mechanical properties of biotechnical system of porous titanium nikelide-bone tissue

The stress-strain state of an implant of a porous titanium nickelide was studied in its placement instead of damaged bone tissue. A value of open porosity of a titanium nickelide sample was determined by the data obtained in processing of SEM images as well as by the liquid saturation method. The applicability of the technique for assessing the open porosity according to scanning electron microscopy was demonstrated. The physico-mechanical parameters of composites of titanium nickelide-connective bone tissue and titanium nickelide-spongy bone tissue were determined. In a SolidWorks software package a volume model of an implant-bone system was developed, and calculations of stresses and shears were carried out. It was found that upon bone tissue ingrowth into the porous structure of TiNi a stress distribution in the composite and bone tissue is leveled.     

Accelerator-driven sub-critical reactor system (ADS) for nuclear energy generation

In this talk we present an overview of accelerator-driven sub-critical reactor systems (ADS), and bring out their attractive features for the elimination of troublesome long-lived components of the spent fuel, as well as for nuclear energy generation utilizing thorium as fuel. In India, there is an interest in the programmes of development of high-energy and high-current accelerators due to the potential of ADS in utilizing the vast resources of thorium in the country for nuclear power generation. The accelerator related activities planned in this direction will be outlined.     

Effect of polarization on population transfer in H2 by stimulated Raman transition with partially overlapping laser pulses

Polarization effects on population transfer by stimulated Raman transition using overlapping time dependent pump and Stokes laser pulses from the ground X ¹Σ _g ^/+ (v _g=0, J _g=1) level of H₂ to the final X ¹Σ _g ^/+ (v _f=1, J _f=1) level via the intermediate B ¹Σ _u ^/+ (v _i=14, J _i=0,2), C ¹Π _u ^/+ (v _i=3, J _i=2) and C ¹Π _u ^/− (v _i=3, J _i=1) levels have been theoretically investigated by applying the density matrix formalism. We have studied in detail the dependence of the population transfer on time delay between two pulses for the cases of on-resonance excitations considering linear parallel and same-sense circular polarizations of the fields. The pump and Stokes fields are taken as having Gaussian pulse shapes with peak intensities I _P ^/0 (I _S ^/0 )=2 × 10⁶ and 1 × 10⁷ W/cm². Density matrix equations have been solved for each value of the magnetic quantum number M _g(0, ±1) of the initial ground level taking into account the M _g dependence of the Rabi frequencies. M _g — averaged population transfer to the final level has also been calculated. For resonance excitations to the B(14, 0) or C(3, 1) levels, appreciable population transfer is achieved for intuitive pulse order for some particular values of M _g and M _i (magnetic quantum number of the resonant intermediate level) depending on the nature of polarizations. The calculated values of M _g — averaged population transfer for the two cases of polarizations show that for on-resonance excitation to the B(14, 0) or the C(3, 1) level, linear parallel polarization of the laser fields yield more transfer efficiency whereas for resonance excitation to the B(14, 2) level, larger population transfer results from the same-sense circular polarizations. For resonance excitation to the C(3, 2) level, M _g — averaged population is found to be almost polarization independent. The calculations for the six-level H₂ system reveal some interesting features of polarization effects on the population transfer efficiency.     

Production of thick YBa2Cu3O7-δ films on sapphire with a cerium oxide sublayer

The feasibility of producing high-quality films of the high-temperature superconducting material YBa₂Cu₃O_7-δ with thicknesses up to 2.6 μm by dc magnetron sputtering is demonstrated. It is found that inclusions consisting of CuO and YBa₂Cu₃O₈ coexist with the growing film and are “sinks” for defects, nonstoichiometric atoms, and mechanical stresses. X-ray diffraction and Rutherford backscattering studies show that the structural perfection of the films increases as the thickness is increased in the proposed production regime. Zh. Tekh. Fiz. 69, 132–136 (September 1999)     

Pellet freezing of in vitro produced bovine embryos using dry ice

In vitro produced bovine embryos were frozen by pellet freezing or vitrification method. In the pellet freezing method, the embryos were cooled on the dry ice and then frozen as pellets. At warming, the pellets were immersed directly into 0.5 M sucrose. The survival rates of blastocysts frozen by the pellet freezing method were higher (P<0.01) in 40% ethylene glycol (EG) than those in the lower concentrations (20 and 30% EG). Higher survival rates of blastocysts frozen by the pellet freezing method were obtained but the development rates did not differ, as compared with those by the vitrification method. There were no significant differences between the pellet freezing and vitrification method in the frequencies of post-thaw survival of hatched blastocysts. These results demonstrate that the pellet freezing method using dry ice can be used successfully for the cryopreservation of blastocysts.     

Steady streaming around a spherical drop displaced from the velocity antinode in an acoustic levitation field

The steady (acoustic) streaming associated with a sphericaldrop displaced from the velocity antinode of a standing waveis studied. The ratio of the particle size to the acoustic wavelengthis treated as small but non-zero, and the solution is developedin the form of a two-term expansion in terms of the correspondingsmallness parameter. The drop viscosity is assumed to be muchhigher than that of the surrounding fluid, which is the casefor a drop in a gas medium. There are essentially three distinctregions where the steady streaming flow is analysed: insidethe drop (internal circulation), in the Stokes shear-wave layerat the surface on the gas side, and the gas outside the Stokeslayer (the outer streaming region). Solutions for the internalcirculation and the outer streaming are obtained in the limitof small Reynolds number. Despite the gas-to-liquid viscosity ratio being small, the outerstreaming may be dramatically affected by the fact that thesphere is liquid as opposed to solid. The parameter that measuresthe effect of liquidity is essentially the viscosity ratio dividedby the relative (to the particle size) thickness of the Stokeslayer. The case of a solid sphere is recovered by letting thisparameter go to zero.     

Model of thermal fatigue of a copper surface under the action of high-power microwaves

The accelerating structures of modern supercolliders, as well as the components of high-power microwave electron devices operated in strong cyclic electromagnetic fields should have long lifetimes. Along with the electric breakdown, the surfaces of these microwave components deteriorate and their lifetimes decrease due to thermal strains and subsequent mechanical loads on the surface metal layer. The elementary theory of thermal fatigue was developed in the 1970s. In particular, a model of metal as a continuous medium was considered. Within the framework of this model, thermal fatigue is caused by the strains arising between the hot surface layer and the cold internal layer of the metal. However, this theory does not describe all the currently available experimental data. In particular, the notion of “safe temperature” of the heating, i.e., temperature at which the surface is not destroyed during an arbitrarily long series of pulses, which was proposed in the theoretical model, is in poor agreement with the experiment performed in the Stanford Linear Accelerator Center (SLAC, USA). In this work, the thermal-fatigue theory is developed on the basis of consideration of the copper polycrystalline structure. The necessity to take it into account was demonstrated by the results of the SLAC experiment, in which a change in the mutual orientation of copper grains and the formation of cracks at their boundaries was recorded for the first time. The developed theory makes it possible to use the experimental data to refine the coefficients in the obtained formulas for the lifetime of the metal surface and to predict the number of microwave pulses before its destruction as a function of the radiation power, the surface-temperature increase at the pulse peak, and the pulse duration.