No abstract available

No abstract available

[en] Relative densities and relative massic heat capacities have been measured for aqueous solutions of Y(ClO₄)₃, Yb(ClO₄)₃, Dy(ClO₄)₃, and Sm(ClO₄)₃ at T=(288.15,298.15,313.15, and 328.15) K and p=0.1 MPa. These measurements were made in the concentration range 0.01624≤m/(mol·kg^-1)≤0.41822 using a Sodev 02D Vibrating Tube Densimeter and a Picker Microflow Calorimeter, respectively. To counter the potential effects of hydrolysis, aqueous solutions of the investigated salts were acidified with perchloric acid. After correcting for the presence of the acid, the measured properties were used to calculate apparent molar volumes and apparent molar heat capacities for solutions of the perchlorate salts in water. The calculated apparent molar properties were modeled at each investigated temperature using Pitzer ion interaction equations to produce estimates of apparent molar volumes and heat capacities at infinite dilution. In addition, the temperature dependences of the apparent molar properties of each salt were found to be well modeled by temperature dependent Pitzer ion interaction equations. The Helgeson, Kirham, and Flowers equations of state were incorporated into the Pitzer ion interaction equations in order to model the infinite dilution properties of the salts. Single ion volumes and heat capacities of the investigated trivalent metal cations have been calculated and compared to previously reported values

[en] The polarographic behaviour of tetravalent uranium, neptunium and plutonium solvates (U(ClO₄)₄x9DMSO, Np(ClO₄)₄x8DMSO and Pu(ClO₄)₄x8DMSO) in dimethylsulfoxide on mercury drop electrode (m.d.e.) and rotating platinum electrode (r.p.e.) has been studied. All the three compounds undergo two-stage reduction, first to the three-valent state and then to an amalgam (on m.d.e.). On the r.p.e. there is one wave corresponding to the process An⁴⁺ + e → An³⁺. All the uranium reduction waves are irreversible. On the m.d.e. neptunium shows a reversible wave of reduction of Np⁴⁺ to Np³⁺. On the r.p.e. the waves of Np⁴⁺ and Pu⁴⁺ are almost reversible. Chloride-ions did not affect the reduction tetravalent U, Np and Pu. The potential shift of ion pairs U⁴⁺/U³⁺, Np⁴⁺/Np³⁺ and Pu⁴⁺/Pu³⁺ in DMSO as against water is explained in terms of pronounced solvation of tertravalent actinoid ions

[en] Influence of solvent (methanol, acetonitrile, dioxane, DMFA) on complex formation of Np(5) with U(6), Th(4) and Fe(3) is studied. It is established that stability of Np(5) complexes with U(6) and Th(4) increases with donor number decrease. The highest stability is observed in complexes with Fe(3) which has low donor and acceptor numbers. It is noted that solvent molecules located in the NpO₂ equatorial plane influence to some extent electron plane shift from neptunium to oxygen atoms, i.e. anion charge

[en] The changes of activity coefficients of cadmium ions in perchlorate solutions of lithium, sodium, magnesium, calcium, barium and cadmium and silver ions inperchlorate solutions of lithium and calcium are studied at 25 deg C using potentiometric method. It is established that in the given solutions the changes of activity coefficients of cadmium and silver ions are connected only with their hydration. The numbers of hydration for the ions are calculated

[en] In the present study, field amplified sample stacking (FASS) techniques in the nonaqueous capillary electrophoresis method (NACE) were introduced for the on-line concentration of the acrylamide to improve acrylamide detection at 210 nm by diode-array detection. Acetonitrile (ACN) as a nonaqueous solvent permits acrylamide to be protonated through the change of its acid-base chemistry, allowing capillary electrophoretic separation of this compound. Choosing 30 mmol L^-1 HClO₄, 20 mmol L^-1 NaClO₄, 218 mmol L^-1 CH₃COOH in ACN as the separation electrolyte and employing sample stacking methods, the LOD value of acrylamide was decreased to 2.6 ng mL^-1 with electrokinetic injection and 4.4 ng mL^-1 with hydrodynamic injection. Optimized stacking conditions were applied to the determination of acrylamide in several foodstuffs. The method is simple, rapid, inexpensive, and widely applicable for the determination of acrylamide in food samples

[en] Kinetics of Np(5) oxidation with pentavalent vanadium in the HClO₄-NaClO₄ solution at the ion force μ=2-4 is studied. The reaction rate is expressed with the equation -d[Np(5)]dt=k₁[Np(5)][V(5)][H⁺], where k₁=118+-10M^-2xmin^-1 at μ=4 and 25.5 deg C. The energy and entropy of activation are 13.5 kcal/mol and - 14 entr. units respectively. The reaction mechanism includes a slow stage of electron transfer between NpO₂⁺ and VO³⁺ ions

No abstract available

[en] The stability constants (K₁) of the complex compounds of rare-earth perchlorates with benzimidazole have been determined by pH-metric titrations. Nonmonotonic variation of log K₁ as the atomic number of the rare-earth element is increased has been discovered. 9 refs., 1 fig., 1 tab