Effect of the Method of Extraction on the Structural‐Group Composition of Naphthenic Concentrates from Naftalan Crude Oil

Naftalan crude oil is the only crude in the world with high therapeutic efficacy. Its therapeutic properties are due to the chemical composition and basic biologically active components, fossil hydrocarbons – naphthenes with isoprenoid chains, steranes, hopanes, etc. [1 – 8]. The necessity of scientifically substantiated refining and rational use of this crude oil makes the study of its chemical composition and the products made from it for medicine urgent.     

Production of 225Ac and 223Ra by irradiation of Th with accelerated protons

The possibility of producing ²²⁵Ac and ²²³Ra by irradiation of natural ²³²Th with medium-energy protons was examined. Thorium foils were irradiated with 90-, 110-, and 135-MeV protons at the accelerator of the Institute for Nuclear Research, Russian Academy of Sciences, in Troitsk (Moscow oblast). The cumulative production cross sections for ²²⁵Ac were 6.7 ± 0.9, 9.8 ± 1.9, and 13.9 ± 1.5 mb, and for ²²⁷Th (²²³Ra precursor), 43 ± 5, 37 ± 6, and 35 ± 4 mb, respectively. Based on the experimental data and theoretical calculations, the possible yields of ²²⁵Ac and ²²³Ra in irradiation of thick thorium targets at various accelerators were determined. An efficient procedure was suggested for isolating the products from the irradiated targets: ²²⁵Ac, by liquid extraction and extraction chromatography, and ²²³Ra, by sublimation from a thorium-lanthanum melt followed by thermochromatographic separation in metallic titanium columns and extraction-chromatographic isolation of radium. The procedure allows production of large (units of curies) amounts of radiochemically pure ²²⁵Ac and ²²³Ra, which is promising for wide use of these radionuclides in nuclear medicine.     

Thermal and electric conductivity of textured Ni-Cr-W alloy ribbon substrates for high-temperature superconductors

The electric and thermal conductivity, heat capacity, and thermal diffusivity of thin Ni_87.8Cr_9.3W_2.9 alloy ribbons have been measured. It is established that samples with a cubic texture possess better conducting properties than the nontextured ribbons. The electron and phonon components of thermal conductivity have been separated and their temperature dependence has been traced. Anomalies related to the transition of samples to a ferromagnetic state have been found.     

Artificial radioactivity of the White Sea

Vertical profiles of ¹³⁷Cs in bottom sediments collected from various sites of the White Sea are reported. From these profiles, the ¹³⁷Cs inventory in the bulk of sediment was estimated to be 270–3300 Bq m^?2, and the surface contamination of sediment, 7.1–46.5 Bq kg^?1. In the most of the sediment cores, ¹³⁷Cs was detected to a depth of >20 cm. The highest activity of ¹³⁷Cs was usually observed in the 1–2-cm layer. The mean specific radioactivity of ¹³⁷Cs in the seawater was 4.1 Bq m^?3.     

System SrGa2S4-LaGaS3

Phase relations in the SrGa₂S₄-LaGaS₃ system were studied by physicochemical analysis, and the SrGa₂S₄-LaGaS₃ phase diagram was mapped out. The system was found to contain the quaternary compound SrLaGa₃S₇, which melts congruently at 1290 K and has a tetragonal structure. The composition ranges of the SrGa₂S₄-and SrLaGa₃S₇-based solid solutions were determined.