Anodic synthesis of Np(VII) compounds from acetate solutions

A procedure was suggested for the synthesis of Np(VII) compounds by electrochemical oxidation in acetate solutions. The conditions for preparing compounds of type MNpO₄·nH₂O, where M is a single-charged cation of alkali metals, ammonium, silver, guanidinium, or tetraalkylammonium, and of Np(VII) compounds with double-charged cations of alkaline-earth metals, Cu, Cd, and Zn were studied in detail. The compounds were characterized by chemical analysis and by IR and electronic spectroscopy.     

Synthesis and properties of complexes of hexavalent actinides with dimethyl sulfoxide [AnO<Subscript>2</Subscript>(DMSO)<Subscript>5</Subscript>](ClO<Subscript>4</Subscript>)<Subscript>2</Subscript> (An = U,Np, Pu)

The complexes [NpO₂(DMSO)₅](ClO₄)₂ (1) and [PuO₂(DMSO)₅](ClO₄)₂ (2), isostructural to the known uranyl complex, were synthesized in the form of single crystals. Their crystallographic characteristics were determined by single crystal X-ray diffraction. The IR and electronic absorption spectra of the crystalline U(VI), Np(VI), and Pu(VI) complexes were measured and analyzed.     

Speciation, stability, and reactions of Np(III–VII) in aqueous solutions

Published data on the structure of Np ions in acid and alkali solutions, on hydrolysis of Np ions and their complexation with anions and cations, on their redox reactions with water and with each other (disproportionation, reproportionation), and on the effect of anions on this process are analyzed. Possible directions of research in chemistry of Np ions are outlined.     

A Method for Determination of Alcohol Content in Dielectric Liquids by a Longitudinal-Slot Waveguide

A new method is proposed to determine the content of alcohol in dielectric liquids. The method is based on measuring the attenuation of a wave propagating in a rectangular waveguide with a longitudinal slot in its narrow wall, immersed in a liquid under test. The propagation constant of the H ₁₀ mode in such a waveguide is calculated numerically for various parameters of the medium and the waveguide. It is shown that the attenuation of the wave depends on the parameters of the dielectric medium outside the waveguide. Experiment is carried out on two different types of waveguide at frequencies from 29 to 37 GHz with a solution of ethyl alcohol in water as the external medium. The results of the measurements show that the method can be used for the on-line measurement of alcohol concentration during fermentation.     

Solid-phase synthesis of deuterium- and tritium-labeled dopamine using carbon nanomaterials

Various procedures for preparing dopamine labeled with deuterium (²H) and tritium (³H) were considered. The labeled dopamine into which the hydrogen isotopes were introduced by solid-phase halogenation contained, on the average, 2.8 ²H (³H) atoms. The labeled dopamine prepared by solid-phase isotope exchange using nanodiamonds as support contained, on the average, 4.8 ²H (³H) atoms. The process was accompanied by the substrate deamination; as a result, the yield of the labeled analog was low (7–10%). Mass spectrometric analysis shows that the phenolic fragments formed by the dopamine deamination undergo dimerization.     

Role of peroxynitrite in oxidation of f-element ions in HNO3 solutions

Published data on the kinetics of Ce(III) oxidation with ozone in HNO₃ solutions are analyzed. The formation of peroxynitrite in the course of ozonation of nitric acid solutions, hypothesized previously in the literature, is confirmed. Peroxynitrite is capable to oxidize Ce(III), but with time it decomposes to HNO₂ and H₂O₂, which reduce Ce(IV). Similar phenomenon is observed in ozonation of nitric acid solutions of berkelium.     

Influence of the origin of H2O2 on the rate of its reaction with Pu(VI) and Am(V) in acid solutions

Analysis of published data shows that H₂O₂ arising in radiolysis of acidic aqueous solutions is in the excited state and reacts with Pu(VI) and Am(V) faster than in the case when in it is introduced into the system with actinide ions from the outside.     

Synthesis, crystal and molecular structure, and spectral properties of guanidinium salt of complex uranyl 2-methoxybenzoate

A crystalline uranyl 2-methoxybenzoate, [C(NH₂)₃][UO₂L₃]·H₂O, was synthesized. Its structure was determined by single crystal X-ray diffraction, and the electronic and IR spectra were recorded. The coordination number of the U atom is 8, with methoxyl O atom not involved in coordination bonding with uranyl. The structure contains a system of hydrogen bonds with water molecule of crystallization and guanidinium cation acting as proton donors. The electronic absorption spectrum of the crystalline complex has a pronounced vibronic structure, whereas in the solution spectrum all the lines are strongly broadened. This may be due to dissociation of the complex anion in solution, which leads to superposition of several spectra. In the IR spectrum, there is a set of band characteristic of guanidinium cations. The uranyl group in [C(NH₂)₃][UO₂L₃]·H₂O has almost symmetrical structure. Therefore, only the band of its antisymmetric vibrations is observed in the IR spectrum.     

Upgrading the Design of Cruciform Fuel Elements to Increase their Heat-Engineering Characteristics

The change occurring in the heat-engineering characteristics of a cruciform fuel element in a SM reactor as a result of the change in the characteristic dimensions of the fuel element, such as the diameter of the circumscribing circle, the indentation radius, and the rounding radius of a lobe, and as a result of the presence of a central displacer in the element is examined. The optimal values of the indentation radius and rounding radius of a lobe are determined to be 0.5 mm. It is shown that the presence of a central displacer in a fuel element substantially decreases the maximum temperature of the kernel and decreases the coefficient of nonuniformity of the heat flux density. For the same maximum kernel temperature in a standard fuel element and a fuel element with a displacer, the maximum heat flux density in the latter element gives an additional margin up to the crisis of heat transfer.__________Translated from Atomnaya Energiya, Vol. 98, No. 4, pp. 274–280, April, 2005.