Dielectric Spectra and d-bands Structure of Germanium,Tin, and Lead Tellurides

Russian Physics Journal - The known experimental absorption spectra were used to calculate the dielectric spectra of GeTe, SnTe, and PbTe crystals in the region of electron transitions from the...     

Reaction of 2-trifluoroacetyl-1,8-Bis(dimethylamino)naphthalene with strong organic bases: Deprotonation of 1-NMe2 group resulting in the formation of Benzo[g]indole derivatives versus nucleophilic addition to CO group

A novel approach to pyrrole ring closure in 2-trifluoroacetyl- and 2-ethoxycarbonyl-1,8-bis(dimethylamino)naphthalenes via treatment with 2-lithium-1,8-bis(dimethylamino)naphthalene producing the corresponding benzo[g]indole derivatives, was examined with different alkyl- and aryllithium compounds as well as with LDA. It was found that the highest yields of benzo[g]indoles (up to 70%) are obtained with aryllithium reagents when they contain NMe₂ group in ortho-position to the carbanionic centre. In all other cases the formation of acyclic alcohol arising from ordinary intermolecular addition of the carbanion to the CO group strongly prevails. The dramatic facilitation of deprotonation of the N-Me group in substrate followed by pyrrolic cyclization in the case of 2-lithium-N,N-dimethylanilines was explained through a specific structure of the reaction transition state.     

Yttria stabilized zirconia solid electrolyte surface modification with ZrO<Subscript>2</Subscript>, Y<Subscript>2</Subscript>O<Subscript>3</Subscript>, and ZrO<Subscript>2</Subscript> + 9 mol % Y<Subscript>2</Subscript>O<Subscript>3</Subscript> films

The surface of ceramic electrolyte ZrO₂ + 9 mol % Y₂O₃, hereinafter referred to as YSZ (abbreviated yttria stabilized zirconia), was modified with 0.1 to 0.2 μm oxide films of ZrO₂, Y₂O₃, and YSZ (same composition as substrate) by dip coating in alcohol solutions of the relevant salts and further annealing. The results of scanning electronic microscopy and X-ray diffraction evidence epitaxial film growth. By means of impedance spectroscopy at the temperatures of 500 to 600°C, the effect of YZS electrolyte surface modification with ZrO₂, Y₂O₃, and YSZ films to the polarization resistance of silver electrode was studied.     

Fixation of micelle structure by monomer polymerization: Hydrodynamic properties of polymerized micelles

Polymerized and nonpolymerized micelles of N-acryloyl-11-aminoundecanoic acid and its sodium salt in water and dimethylformamide are studied by viscometry, isothermal diffusion, and dynamic light scattering. It is revealed that the hydrodynamic sizes of polymerized micelles (PMs) obtained via polymerization of the surfactants in aqueous solutions at low concentrations of the latter are significantly larger than those of the starting surfactant micelles. In dimethylformamide, as the surfactant concentration at which the synthesis is carried out is increased, the hydrodynamic size of PMs, which is calculated in terms of the cylindrical particle model, rises from 25 to 220 nm. The formation of additional internal crosslinks reduces the equilibrium rigidity of the PM chains by a factor of 1.5–2.     

Comparison between the parameters of a one-phase arc with copper and steel electrodes ignited in nitrogen and in air

The characteristics of an open one-phase arc with gas stabilization in electrode units are studied. The arc is ignited between copper and steel electrodes in nitrogen and in air. The amplitude values of the current and voltage reach 9–10 A and 650–1600 V, respectively. Current and voltage oscillograms, as well as dynamic I–V characteristics, are presented. The time variation of the conductivity, the discharge power, and the spectral composition and integral radiation losses of the arc column are compared when the electrodes are made of copper and steel.     

Groups whose lattice of centralizers is a sublattice of the subgroup lattice

An earlier conjecture suggests that the lattice of centralizers is modular in the title groups. We prove it to hold for two classes of groups whose lattice of centralizers has finite length — groups with the normalizer condition and locally finite groups.Translated fromAlgebra i Logika, Vol. 33, No. 5, pp. 475–513, September–October, 1994.     

Renormalization group in the theory of developed turbulence. The problem of justifying the Kolmogorov hypotheses for composite operators

In this paper, the stochastic theory of developed turbulence is considered within the framework of the quantum field renormalization group and operator expansions. The problem of justifying the Kolmogorov-Obukhov theorem in application to the correlation functions of composite operators is discussed. An explicit expression is found for the critical dimension of a general-type composite operator. For an arbitrary UV-finite composite operator, the second Kolmogorov hypothesis (the viscosity-independence of the correlator) is proved and the dependence of various correlators on the external turbulence scale is determined. It is shown that the problem involves an infinite number of Galilean-invariant scalar operators with negative critical dimensions. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 110, No. 1, pp. 122–136, January, 1997.     

Experimental study of the discrete component in the noise spectrum of supersonic flows

The discrete component in the noise spectrum of an inefficient supersonic stream flowing into a flooded space is studied experimentally. The effect of a discrete tone on the average parameters of the initial and main portions of the stream is examined. It is found that the lengthl ₀ of the supersonic part of the stream decreases linearly as the level L* of the discrete component acting on the base of the stream is increased. It is also shown experimentally that the oscillations in the density jumps at the ends of the first and second cells of the stream take place out of phase.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 163–166, July–August, 1976.     

Nonsteady supersonic flow over spiked bodies

In longitudinal supersonic flow over spiked cylinders nonsteady regimes can occur in which a separation zone is periodically generated at the spike, grows vigorously in size, and then vanishes. Several authors [1–6] have investigated the physical pattern of flow with separation zone fluctuations (using shadowgraphs) and have determined the boundaries of existence of the nonsteady regime as a function of the ratio between the spike length and diameter of the cylinder. The authors, however, did not systematically study the dependence of the pulsation frequency on the freestream Mach and Reynolds numbers or on the relative diameter and tip angle of the spike. We have undertaken such an investigation. We are concerned primarily with the influence of the dimensionless parameters on the Strouhal number Sh of the separation zone pulsations at a spike attached to the front of a flat-ended cylinder. Earlier investigations [4–6] have been carried out using motion pictures with film speeds up to 32·10³ frames/sec. In the present study we used high-speed motion pictures with a speed of 6.25· 10⁵ frames/sec. This speed allowed us to determine the precise sequence of phases of the pulsations and their relative durations, as well as the speed at which the boundaries of the separation zone move.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 118–124, September–October, 1976.