Determination of Oxygen in Halide Fluorotantalate Melts by IR Spectroscopy

The possibility of determining oxygen as impurity in halide melts containing potassium heptafluorotantalate by IR spectroscopy was investigated. These melts are used for obtaining tantalum powders by the sodium–thermal method. It was found that a linear correlation exists between the oxygen concentration in the melt c _O(c _O= 0.05–1.0 wt %) and the ratio of intensities of IR absorption lines in the region of 1200–400 cm^–1. This correlation can be used for determining oxygen in the melt and for predicting the concentration of this element in sodium–thermal tantalum powders.     

The Coherent Production of the (K +π0) System by K + Beam on Copper Nuclei at the OKA Setup

Journal of Experimental and Theoretical Physics - On the statistics of ~1.7 × 108 interactions of positively charged kaons on copper nuclei, coherent events of the K+π0 system production...     

Influence of the particle size distribution of potassium heptafluorotantalate on the characteristics of sodium-reduced tantalum powders

Two versions of heterophase sodium-thermic reduction of potassium heptafluorotantalate were studied. One version implies initiation of the reaction in a homogeneous mixture of solid K₂TaF₇ and sodium flux, and the other, supply of solid K₂TaF₇ onto the surface of liquid sodium occurring above the molten halides. The surface area of the tantalum powder was correlated with the K₂TaF₇ particle size. The formation mechanisms for the tantalum powder particles were discussed for different reduction procedures. The conditions for preparation of powders with the specific surface area of ca. 4 m² g⁻¹ were identified.     

Diagnostics of the Degree of Calcification of Atherosclerotic Plaque by Laser-Induced Fluorescence

The luminescence of highly calcified atherosclerotic plaque in comparison with the luminescence of a normal wall of the vessel was studied in vitro (the luminescence was excited by a CW argon laser with λ = 488 nm or a pulsed nitrogen laser with λ = 337 nm). The mass-spectroscopy analysis of the plaque was carried out with a LAMMA-1000 system. It is ascertained that the specific shape of the luminescence spectrum with maximum at λ = 560 nm (under argon laser excitation) and λ = 485 nm (under nitrogen laser excitation) is typical of a highly calcified plaque (Ca content ≈38 %) and is similar to the luminescence spectrum of ordinary chalk.     

Tetracyclines Communication 34. Synthesis of the 6-demethyltetracycline analog 2-decarbamoyl-4-dedimethylamino-6,10,12-tridehydroxy-6-demethyl-11a,12-dihydrotetracycline

Summary A tetracyclic analog of 6-demethyltetracycline-2-decarbamoyl-4-dedimethylamino-6,10,12-tridehydroxy-6-demethyl-11a,12-dihydrotetracycline-was synthesized.For preliminary communication see [1].The authors thank L. B. Senyavina for the measurement of infrared spectra.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1039–1044, June, 1965     

Numerical integration methods for the Takagi-Taupin equations for crystals of rectangular cross section

Two independent methods for calculation of the rocking curves for laterally bounded crystals are developed. Numerical simulation of diffraction for crystals of different sizes is performed. The results obtained using the dynamical theory of diffraction are compared to those obtained in the kinematic approximation.     

Theory of X-ray diffraction from a nonideal crystal with a trapezoidal cross section

The theory of X-ray diffraction from a nonideal lateral crystal with a trapezoidal cross section in the Born (kinematical) approximation has been developed. Distortions of the crystal structure are caused by continuous (nonrandom) lattice strains and randomly distributed defects. Continuous lattice strain is a combination of elastic bending of atomic planes and a linear variation in the interplanar spacing with increasing distance from the crystal surface. Within the method of triple-crystal X-ray diffraction, numerical simulation of the angular intensity distribution of coherent and diffuse scattering has been performed for different continuous and random lattice strains in the lateral and vertical directions.