Variations of Cosmogenic Radionuclide Production Rates in Chondrites of Known Orbits

Doklady Physics - The results of multiyear investigations of cosmogenic radionuclide production rates along the orbits of 42 chondrites that fell to the Earth between 1959 and 2016 are presented....     

Effects of the diffusive acceleration of particles by shock waves in the primordial matter of the solar system

The effects of the shock wave diffusive acceleration of particles are considered in the case of formation of isotopic relations of the anomalous Xe-HL component of xenon in relic grains of nanodiamonds in chondrites. It is shown that this component could be formed and captured simultaneously with the nanodiamond synthesis in the conditions of the explosive shock wave propagation from supernova outbursts. The specificity of isotopic composition of Xe-HL is due to the high hardness of the spectrum of nuclear-active particles at the shock wave front and its enrichment with heavy isotopes. The spallogenic nature of both the anomalous and normal components of xenon is ascertained, and the role of the subsequent evolutionary processes in the change of their isotopic systems is shown. Experimental evidence of the formation of the power law spectrum of particles with the spectral index γ ∼ 1 by the supersonic turbulence during the carbon-detonation supernova SnIa explosion is obtained; this perhaps opens new perspectives in studying the problem of the origin of cosmic rays. It is shown that at the stage of free expansion of the explosive shock wave, the degree of compression of the matter at the wave front was σ = 31 (the corresponding Mach number M ∼ 97); this led to a 31-fold increase of the magnetic field as well as of the maximum energy of accelerated particles, so that even the energy of protons reached ∼ 3 × 10¹⁵ eV, i.e., the “knee” region.     

Selective Phosphorylation of Hydroximidates with Phosphorus Oxychloride

Russian Journal of General Chemistry -     

Facile synthesis of 6-aryl-3-pyridyl-1,2,4-triazines as a key step toward highly fluorescent 5-substituted bipyridines and their Zn(II) and Ru(II) complexes

A wide series of substituted bipyridines were obtained through the synthesis of 1,2,4-triazines and their aza Diels-Alder reactions. The reported method facilitates the synthesis of functionally diverse bipyridines that provides fine-tuning of photophysical properties of new ligands and their Zn(II) and Ru(II) complexes. Some of substituted bipyridines exhibit ‘off-on’ fluorescence response toward Zn²⁺ cations.     

Structure and the electrical and magnetic properties of perovskite-like Gd x Cu3V4O12 oxide

A new perovskite-like compound Gd _x Cu₃V₄O₁₂ (x = 0.67?0.73) is synthesized under high pressures (P = 4?9 GPa) and at high temperatures (T = 1000°C). Its structure (space group Im3, Z = 2, a = 7.2930(5) ?) is estrablished by X-ray analysis. The bond lengths and bond angles are determined. The temperature dependences of electrical resistivity (10?C300 K) and magnetic susceptibility are studied. The high-pressure Gd _x Cu₃V₄O₁₂ phase is found to have a semi-conductor type of conductivity and paramagnetic properties.     

Anodic stripping determination of Pt(IV) based on the anodic oxidation of In from electrochemically deposited Pt–In alloy phases

A simple, rapid, and sensitive anodic stripping voltammetric method for the determination of Pt (IV) is described. It is based on depositing an intermetallic indium–platinum alloy phase on the surface of a modified graphite electrode, and recording the oxidation peak of indium from that alloy phase with the help of linear scan voltammetry. A systematic study of the behavior of different In–Pt phases revealed that the peak potential of indium oxidation from the different phases can be explained on the basis of simple thermodynamic considerations. Different alloy phases have characteristic peak potentials. For the purpose of analysis, it is possible to choose such conditions that only one specific alloy phase forms, viz. PtIn. This is the case for a concentration (milligrams per liter) ratio of In(III)/Pt(IV)?=?50,000:1, at least.     

Synthesis of 3-Substituted Arylpyrazole-4-carboxylic Acids

A method was suggested for preparing previously unknown 3-aryl-substituted pyrazole-4-carboxylic acids, involving Vilsmeier formylation of semicarbazones of 26 available mono- and disubstituted acetophenones and 2-acetylthiophene followed by oxidation of the resulting 3-aryl-substituted pyrazole-4-carboxaldehydes under the action of potassium permanganate. The mechanism of the formylation reaction is discussed. The method successfully works even with acetophenones containing alkyl substituents. In the latter case, an additional stage that involves isolation of pyrazole-4-carboxylic acids as their silyl esters is used.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 829–835.Original Russian Text Copyright © 2005 by Lebedev, Lebedeva, Sheludyakov, Kovaleva, Ustinova, Kozhevnikov.