Photochemistry of tetraalkylammonium tetrachlorocuprates in low-temperature matrices

The product composition and the principles of photochemical transformations of tetrahexylammonium tetrachlorocuprate [(RH)₄N⁺]₂[Cu^IICl₄]²⁻ (RH = C₆H₁₃) in 2-chlorobutane at 77 K have been found out by ESR spectroscopy. It has been shown that the photolysis of [(RH)₄N⁺]₂ [Cu^IICl₄]²⁻ results in the formation of alkyl radicals (R^⊙), presumably, anions [Cu^ICl₃]²⁻ and organic copper(II) compounds {Cu^IIR}. A reduction in the quantum yield of primary photolysis products during the reaction, nonequivalence of the quantum yield of the buildup of paramagnetic photolysis products to that of [Cu^IICl₄]²⁻ consumption, and a decrease in the total number of paramagnetic particles in the system during the photolysis have been revealed. A photolysis mechanism involving both photochemical and thermal processes is proposed.     

Neutrino oscillations in a homogeneous moving medium

The quasi-classical equation that describes both neutrino flavor oscillations and spin rotation in dense matter is obtained in the framework of quantum field theory. The solution of this equation for homogeneous medium is found. The probabilities of the spin-flavor transitions in unpolarized moving matter are calculated in the two-flavor model. We show that if the medium is at rest the neutrino helicity is conserved and the flavor transition probabilities are equal to those obtained using the phenomenological approach.     

Experimental and numerical study of heat transfer enhancement in a turbulent bubbly flow in a sudden pipe expansion

Results of an experimental and numerical simulation of heat transfer in an upward bubbly flowin a sudden pipe expansion are presented. The experimental study of the heat transfer has been performed using infrared thermography. The measurements of the bubble size before the pipe expansion area were carried out by the shadow photographymethod. The numerical simulation of the bubbly flow structure in the sudden pipe expansion has been performed using the Eulerian approach in the presence of heat transfer between the two-phase flow and the wall surface. The model uses the system of Reynolds-averaged Navier–Stokes equations in an axisymmetric approximation, written with consideration of the back effect of bubbles on the averaged and pulsation characteristics of the flow. It has been experimentally and numerically shown that addition of air bubbles causes a significant (up to 3-fold) increase in the heat transfer intensity, these effects growing with bubble concentration. The largest rise in the heat transfer has been revealed in the region of flow relaxation downstream of the flow attachment point.     

Investigation of the ferroelastic phase transition in the SrMgF4 pyroelectric crystal

A SrMgF₄ compound has been synthesized and a high optical-quality crystal has been grown. Optical-polarization observations, X-ray diffraction analysis, and the measurement of the birefringence Δn _i (t) in the SrMgF₄ crystal have been carried out in the temperature range of 90–1200 K. A second-order improper ferroelastic phase transition accompanied by birefringence anomalies and the symmetry change P112₁ (Z = 12) ? Cmc2₁ (Z = 4) has been discovered at T ₀ = 478 ± 1 K. The crystal remains pyroelectric in both phases. Considerable contributions of the fluctuations of the order parameter have been observed in the temperature ranges of (T ₀ ? T) < 15 K and (T ? T ₀) < 60 K.     

Lattice reorientation in the shear bands of {112}〈131〉 crystallites in an Fe-3%Si alloy

Subregions (0.1 μm) with the {110}〈113〉 orientation form in shear bands in grains with the {112}〈131〉 orientation in a deformed (? ≈ 50%) polycrystalline Fe-3%Si alloy sample. The relationship between the matrix and the subregions in the shear bands is described by a special misorientation close to Σ5. It is assumed that the subregions that have a {110}〈hhl〉 orientation and special misorientation Σ5 with the surrounding matrix and form in the shear bands of crystallites with orientations other than {111}〈112〉 can serve as anomalous growth nuclei during heat treatment because of a high density of special Σ5 boundaries.     

Stable bright and vortex solitons in photonic crystal fibers with inhomogeneous defocusing nonlinearity

We predict that a photonic crystal fiber whose strands are filled with a defocusing nonlinear medium can support stable bright solitons and also vortex solitons if the strength of the defocusing nonlinearity grows toward the periphery of the fiber. The domains of soliton existence depend on the transverse growth rate of the filling nonlinearity and nonlinearity of the core. Remarkably, solitons exist even when the core material is linear.     

Nonstationary Vibrations of Plates Under Periodic Loading

The problem on the nonstationary vibrations of plates under periodic loading is formulated with regard for the damping factor and the initial conditions. A technique for solution of the problem is proposed. It is based on the method of integral Laplace transformations, the theory of residues, and the method of asymptotic approximations. Examples related to the change of the extinction coefficient are considered for different plate materials. A general formula for bending of the plate has been derived     

Polymer nanoparticles loaded with FeCl-tetraphenylporphyrin for binary catalytic therapy of neoplasms

Russian Chemical Bulletin - In order to study the possibility of using a metal complex of the porphyrin series, FeIIICl-tetraphenylporphyrin (FeClTPP), and its polymeric form as antitumor agents...     

Multiple Upsets Induced by Protons and Neutrons in Electronic Devices

Technical Physics - 90-nm SRAM memory integrated circuits and CCD- and CMOS-matrices have been irradiated by nucleon beams of the synchrocyclotron at the Konstantinov Petersburg Nuclear Physics...     

Phonons in Ge/Si quantum dot structures: influence of growth temperature

In this paper we present the results of a Raman study of Ge/Si quantum dot (QD) superlattices grown with different thicknesses of a Si interlayer and at different substrate temperatures. The built-in strain and atomic intermixing in the QDs are deduced from an analysis of optical phonon frequencies of the QDs obtained from Raman spectra of the structures.