Ultra-low-frequency dust-electromagnetic modes in self-gravitating magnetized dusty plasmas

Obliquely propagating altra-low-frequency dust-electromagnetic waves in a self-gravitating, warm, magnetized, two fluid dusty plasma system have been investigated. Two special cases, namely, dust-Alfvén mode propagating parallel to the external magnetic field and dustmagnetosonic mode propagating perpendicular to the external magnetic field have also been considered. It has been shown that effects of self-gravitational field, dust fluid temperature, and obliqueness significantly modify the dispersion properties of these ultra-low-frequency dust-electromagnetic modes. It is also found that in parallel propagating dust-Alfvén mode these effects play no role, but in obliquely propagating dust-Alfvén mode or perpendicular propagating dust-magnetosonic mode the effect of self-gravitational field plays destabilizing role whereas the effect of dust/ion fluid temperature plays stabilizing role.     

Influence of Thermal Treatment of Ti–45Nb Alloy in Ultrafine-Grained State on Its Structural Parameters and Heat Capacity

Russian Physics Journal - The effect of heat treatment of the Ti – 45 wt.% Nb alloy in the ultrafine- and coarse-grained states on its structural parameters (lattice parameters, volumetric...     

Synthesis of the europium organic phosphate and phosphoramide complexes

Organic phosphates and phosphoramidates containing alkoxysilyl group were synthesized and used to obtain the corresponding europium complexes. The latter are shown to be applicable for the formation of organic-inorganic hybrids with the components connected with each other through a chemical bond.     

Femtosecond dynamics of intramolecular photoinduced proton transfer in <Emphasis Type="Italic">N</Emphasis>-substituted 2-(2-aminophenyl)-4H-3,1-benzoxazin-4-ones

Femtosecond dynamics of processes in the excited state of 2-(2-aminophenyl)-4H-3,1-benzoxazin-4-ones has been studied by femtosecond absorption spectroscopy. The rate constants of intramolecular photoinduced proton transfer (IPPT) have been determined for the N-substituted derivatives (0.7–11 ps⁻¹). The IPPT rate constant depends on the inductive constant of the substituent and the potential barrier height, which was calculated by a quantum-chemical method (TDDFT). The multiexponential character of the kinetics of photoinduced absorption by the compounds with a low inductive constant of the N-substituent in the spectral region of the S₁ → S_N absorption and the stimulated emission of the IPPT product is explained by the rapid (∼10 ps⁻¹) relaxation process preceding the IPPT.     

Production of nanodisperse particles of doped yttrium-aluminum garnet by a sol-gel process

Method for synthesis of nanodisperse yttrium-aluminum garnet powders activated with cerium and silicon ions was developed. The method is based on a combination of sol-gel synthesis and coprecipitation of hydroxides of the corresponding metals. The process modes were optimized and the structural, physicochemical, and spectral-luminescent characteristics of the samples obtained were studied.     

Thermochemical synthesis of luminescent materials in the Y<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZnO system doped with Eu<Superscript>3+</Superscript> ions

Powders were synthesized in the yttrium oxide + zinc oxide system doped with europium oxide by the method of redox combustion of a mixture of yttrium, zinc, and europium nitrates in the presence of saccharose (fuel). The structure and the physicochemical and luminescent properties of the particles being formed and of a ceramic on their basis were examined.     

Photochemical synthesis of 1,3-dithiolane derivatives by Wolff rearrangement of 5-diazo-1,3-dithiane-4,6-dione

Russian Journal of Organic Chemistry -     

Peculiarities of exited state intramolecular proton transfer in 2-amino-3-(2′-benzazolyl)-quinolines

It has been shown that a low fluorescence quantum yield of 2-amino-3-(2′-benzoxazolyl)-quinoline (ABO) and 2-amino-3-(2′-benzothiazolyl)-quinoline (ABT) is due to the relaxation process caused by excited state intramolecular proton transfer (ESIPT). Quantum-chemical calculations have revealed that ESIPT in these compounds is characterized by overcoming a potential barrier, with the lower basicity of the proton-accepting moiety in ABO resulting in a higher barrier than in ABT and, thereby, determining a substantial difference in their fluorescence quantum yields.     

Trifluoroacetic Acid as a New Effective Catalyst for Preparing Monolithic Silica Gel by the Sol-Gel Process

Trifluoroacetic acid was proposed as a new effective catalyst for organic sol-gel synthesis. The influence of the solvent (polar or nonpolar, protic or aprotic) on the sol-gel process was studied.     

Nuclear57Fe relaxation in Fe2+-containing NiFe2O4 and CoFe2O4 single crystals

Spin-lattice (T ₁) and spin-spin (T ₂) relaxation times of ⁵⁷Fe nuclei in the single-crystal NiFe₂O₄ and CoFe₂O₄ ferrites containing Fe²⁺ ions have been studied in the temperature range of 4.2–100 K by a spin-echo technique. The peaks of relaxation rates T ₁ ^?1 and T ₂ ^?1 caused by the presence of Fe²⁺ ions were observed for both ferrites in the ranges 38–42 and 28–32 K, respectively. The analysis of the results obtained with invocation of the data on ferromagnetic resonance and the measurements of the temperature dependence of resistivity shows that the mechanism of nuclear relaxation responsible for “impurity” peaks and is a slow relaxation process caused by electron exchange Fe²⁺ ? Fe³⁺, characterized by a low activation energy.