Preparation and properties of viscose staple fibre modified by grafting polyvinyl chloride

Conclusions 1. The authors have obtained modified viscose fibres containing PVC in amounts reaching 25–230% of the weight of cellulose. The molecular weight of the grafted chain varies between 40,000 and 140,000; the degree of conversion of cellulose does not exceed 13–22%.2. It is shown that grafting of PVC increases the absolute strength and elongation of fibres, reduces the loss of wet strength, and reduces the resistance to repeated bending. A marked reduction of the fibre number reduces their strength.3. The results are explained by the probability that graft copolymerization takes place on a supramolecular level.Moscow Textile Institute. Translated from Khimicheskie Volokna, No. 5, pp. 30–32, September–October, 1969.     

The influence of mixing on the epitaxial synthesis of diamond

The effect of intermixing on the synthesis of two concurrent phases, i.e. diamond and graphite, is discussed. An experimental unit is described, and experimental results are presented.     

Crystal structure of the Np(IV) compound [Np(DMSO)7(NO3)](ClO4)3 (DMSO = dimethyl sulfoxide)

The Np(IV) complex [Np(DMSO)₇(NO₃)](ClO₄)₃ was synthesized and studied by single crystal X-ray structural analysis. The crystal structure contains three crystallographically independent formula units. The complex cations [Np(DMSO)₇(NO₃)]³⁺ contain bidentate chelate nitrate ions and DMSO molecules coordinated to the Np atom via O atom. The coordination polyhedra (CPs) of the two crystallographically independent Np atoms can be described as base-monocapped tetragonal antiprisms, whereas the CP of the third crystallographically independent Np atom should be described as a trigonal prism tricapped at lateral faces. In contrast to many other structures of dimethyl sulfoxide complexes of actinide and lanthanide perchlorates, the DMSO molecules and perchlorate ions in the structure under consideration show no disordering.     

Complexation of tetravalent actinides (Th, U, Np, Pu) with 2,6-pyridinedicarboxylic acid in aqueous solutions

The interaction of An(IV) ions (An = Th, U, Np, Pu) with 2,6-pyridinedicarboxylic acid (2,6-PDCA) in solutions was studied by spectrophotometry. The electronic absorption spectra of the individual complex species An(PDC)²⁺, An(PDC)₂, and An(PDC) ₃ ^2? (PDC^2? is 2,6-PDCA anion; An = U, Np, Pu) were obtained. At [2,6-PDCA] ? 3[An(IV)] + 0.01 M and [H⁺] ? 0.2 M, the prevalent An(IV) species are the complexes An(PDC) ₃ ^2? . Their overall stability constant exceeds 10²⁵ L³ mol^?3 and increases in the series from Th(IV) to Pu(IV) by ～8 orders of magnitude. Very high stability of An(IV) complexes with 2,6-PDCA anions leads to significant shifts of the redox potentials of couples involving An(IV). In particular, large difference in the stability of An(III) and An(IV) complexes is responsible for the fact that Pu(III) in the presence of 2,6-PDCA is readily oxidized with atmospheric oxygen to Pu(IV).     

Oxidation of Np(V) and Np(IV) with Fe(CN) 6 3− ions in carbonate solutions

The formal potential of the Fe(CN) ₆ ^3? /Fe(CN) ₆ ^4? couple in 1 M NaHCO₃ and 1–2 M Na₂CO₃ solutions was determined. It is equal to 505 and 510 mV, respectively, exceeding the potentials of the Np(VI)/(V) and Np(V)/(IV) couples in carbonate solutions. The equilibrium of the reaction Np(V) + Fe(CN) ₆ ^3? = Np(VI) + Fe(CN) ₆ ^4? was studied. Fe(CN) ₆ ^3? ions oxidize Np(IV) to Np(V) and then to Np(VI). The arising Np(VI) oxidizes Np(IV). The Np(IV) oxidation accelerates in going from NaHCO₃ to Na₂CO₃. An increase in [Na₂CO₃] or in the ionic strength (by adding neutral salts) decelerates the oxidation. Np(IV) introduced in an HCl solution reacts with Fe(CN) ₆ ^3? or with Np(VI) faster than Np(IV) introduced in a Na₂CO₃ solution. The activation energy of the reaction of Np(IV) with Fe(CN) ₆ ^4? in the range 20–45°C is 107 kJ mol^?1. The reaction mechanism involves formation of the activated complex from ions of Np(IV) hydroxocarbonate and oxidant.     

Reduction of neptunium(V) and uranium(VI) with iron(II) in bicarbonate solutions

Reaction of Np(VI) compounds with Fe(II) in bicarbonate solutions was studied. Reaction of Np(V) with Fe(II) in the presence of phthalate ions was briefly considered. Iron(II) compounds reduce Np(V) compounds in solutions saturated with Ar or CO₂ at any concentrations of bicarbonate ion. At [Na(K)HCO₃] > 0.86 M, Np(V) is reduced during mixing the reactants and recording the spectra. The reaction of Fe(II) with Np(V) in dilute bicarbonate solutions is substantially slower, probably owing to a sharp decrease in the solubility of the Np(V) carbonate complexes. The solubility of the Np(V) compounds increases after saturation of the dilute bicarbonate solutions with CO₂. However, in this case reduction remains slow. Uranium(VI) carbonate complexes are reduced with Fe(II) compounds in dilute bicarbonate solutions. The reaction products formed at elevated temperatures are UO₂ and FeOOH.     

Structure and Some Properties of a Double Neptunyl(V) Cesium Molybdate,Cs[NpO<Subscript>2</Subscript>MoO<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)]

A double neptunyl(V) cesium molybdate, Cs[NpO₂MoO₄(H₂O)], was studied by single crystal X-ray diffraction. Crystal data: rhombic system, a = 9.478(2), b = 7.900(1), c = 10.499(2) Å; space group Pnna, Z = 4, d = 5.05 g cm^?3, R = 0.030. The compound has a framework structure; the coordination polyhedron of the Np atom is a distorted pentagonal bipyramid with the equatorial positions occupied by four O atoms of four molybdate groups and an O atom of the coordinated water molecule. The IR and visible absorption spectra of this compound and of Cs₂[(NpO₂)₂Mo₂O₈] whose structure had been determined previously were measured. The NpO ₂ ⁺ stretching vibration frequencies in the IR spectra of these compounds virtually coincide. Incorporation of the O atom of the Mo-O-Mo bridge into the first coordination sphere of the neptunyl(V) ion in Cs₂[(NpO₂)₂Mo₂O₈] exerts the same disturbing effect on the electronic absorption spectrum as does the cation-cation interaction with one of the O atoms acting as a bridge between two Np atoms.     

Reconditioning of the pressure face of the waterworks facility on Sytykan River

The possibility of creation of a frozen-ground curtain in permeable soils with a permeability of 800 – 900 m-day with the help of a liquid system with forced circulation of kerosene is shown.Translated from Gidrotekhnicheskoe Stroitelstvo, No. 12, December 2004, pp. 14 – 22.