Effect of the Structure of <Emphasis Type="Italic">o</Emphasis>-Methyleneoxyphenyldiphosphine Dioxides on Their Extractive Power and Selectivity in Nitric Acid Solutions

Extraction of trace amounts of Pu(IV), U(VI), Th(IV), Am(III), and REEs(III) from nitric acid solutions with o-methyleneoxyphenyldiphosphine dioxides with phenyl (I) and butyl (II) substituents at the phosphoryl group is studied. The stoichiometry of extractable complexes in dichloroethane is determined. Changing the butyl substituents for phenyl ones increases the effective extraction constants of Pu(IV), Th(IV), and Am(III) and decreases that of U(VI). In extraction from 3 M HNO³, the Pu(IV)/U(VI) and Th(IV)/U(VI) partition coefficients are higher with reagent I, and the Pu(IV)/Am(III) and U(VI)/Am(III) partition coefficients, with reagent II.     

Synthesis and Characteristics of Double Np(VI) Potassium and Pu(VI) Potassium Silicates K[(NpO2)(SiO3OH)]·H2O and K[(PuO2)(SiO3OH)]·H2O

K[(NpO₂)(SiO₃OH)]·H₂O (I) and K[(PuO₂)(SiO₃OH)]·H₂O (II) were prepared by hydrothermal synthesis at 120°C, and their IR and near-IR spectra were measured. The unit cell parameters of the compounds were determined from powder X-ray patterns [a = 7.068(1), b = 7.064(2), c = 6.640(1) Å. = 106.68(1)°, V = 317.6 ų (I); a = 7.102(1), b = 7.100(2), c = 6.637(1) Å, = 107.62(1)°, V = 318.9 ų (II)]. These compounds are isostructural with potassium boltwoodite K[(UO₂)(SiO₃OH)]·H₂O.     

Model of the (PuO2)2SiO4·2H2O Crystal Structure,Based on Powder X-ray Diffraction Data

Plutonyl orthosilicate dihydrate (PuO₂)₂SiO₄·2H₂O was prepared by a hydrothermal procedure at 180°C. Its powder diffraction pattern (Guinier camera, CuK ₁ radiation) was indexed in the tetragonal crystal system: a 6.912(3), c 18.563(3) Å, space group I4₁/amd. The structure of (PuO₂)₂SiO₄·2H₂O is similar to the known structures of (UO₂)₂SiO₄·2H₂O and (UO₂)₂GeO₄·2H₂O, but differs in the mutual orientation of the chains of coordination polyhedra of actinide atoms (pentagonal bipyramids) sharing common equatorial edges.     

Kinetic Features of Labeled Product Formation under the Action of Atomic Tritium on Frozen Solutions and Lyophilically Dried Mixtures of Amino Acids

Formation of labeled amino acids in reactions of their lyophilically dried mixtures and frozen solutions with atomic tritium generated by thermal activation was studied in relation to the reaction time and pressure of molecular tritium. The molar radioactivity of the amino acids is a complex function of the reaction time. At short reaction times, the radioactivity of the amino acid depends primarily on its concentration in the near-surface layer. At long labeling times, in the case of surfactants, the yield of labeled products can decrease owing to side reactions. The influence of water on the rate of formation of labeled products and its role in thermalization of hot tritium atoms in the target is discussed. An increase in the tritium pressure in the system increases the initial radioactivity of the target but affects the yield of the labeled amino acids insignificantly. Recommendations are formulated on optimizing the conditions for labeling of biological macromolecules in their structural studies by tritium planigraphy.     

Some two-dimensional heat-conduction problems with mixed boundary conditions

Successive application of a series of conformal mappings is used to determine the steady-state heat flow and temperature fields in two-dimensional rectangular configurations with mixed boundary conditions. A uniform medium is considered. The analytical solutions are compared with results obtained by means of an electro -hydrodynamic analog.     

Effect of ice content and cryogenic structure of frozen ground on the bearing capacity of a pile

Conclusions 1. The limit resistance of piles in permofrost, especially of driven and bored-driven piles, is determined not only by the amount of ice I_C but also by the character of ice distribution in the mass, i.e., by the cryogenic structure.2. Horizontally bedded structures as compared with vertically bedded and cellular, with like content of ice, provide higher bearing capacity of the piles (on an average, by 17%).3. The effect of structure in determining the bearing capacity of a pile may be considered by introducing the structure coefficient K_T into the formula for calculation; the values of this coefficient for horizontally bedded structure have been given in Table 1. For vertically bedded and cellular structures, K_T = 1 is recommended, and for massive soils, K_T = 0.Siberian Branch of the Scientific-Research Institute of Foundations and Underground Structures (SD NII Osnovanii) Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 20–21, November–December, 1976.