Protective Properties of Zinc-Rich Coatings: An Impedance Method Estimate

The impedance of zinc-rich polymer coatings on steel in a 3-% NaCl solution is studied. The electrochemical behavior of the electrode is satisfactorily described by an equivalent circuit that contains a constant-phase element, which reflects fractal properties of the zinc surface in the binder. From the results of calculations of the circuit elements for metal-rich electrodes with different zinc contents computed are fractions of the active area of the surface of the coating and its fractal dimensionality.     

Quinones

A number of 2-methyl-3-carbethoxy-5-hydroxy-6-arylindole derivatives were obtained by the condensation of aryl-p-benzoquinones with -aminocrotonate esters and N-substituted -aminocrotonate esters. The position of the aryl substituent was established by means of the NMR spectra.See [8] for Communication XLVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1634–1636, December, 1970.     

Separation of pesticides by high-performance liquid chromatography with amperometric detection

The possibility of the amperometric detection of a number of pesticides, such as benomyl, thiram, linuron, metoxuron, desmedipham, dicuron, lenacil, and fludioxonil, widely used in agrochemical practice was studied. The effect of the working electrode material (glassy carbon, nickel, and gold) and the type of the electrochemical cell on the value of the analytical signal was studied using the example of thiram. It was found that the optimum potential of the working electrode in analyzing a pesticide mixture was 1400 mV. The dependence of the analytical signal on the pesticide concentration was shown to be linear. The detection limits for the analytes were calculated. Using a 100-μL sample loop, all of the studied pesticides can be determined at the level of the maximum permissible concentration (MPC). The amperometric determination of seven pesticides at the level of MPC in real samples was shown by the examples of model mixtures dissolved in tap water and beetroot juice.     

Separation of cationic and anionic conductivity constituents in solid polymer electrolytes comprising a copolymer of acrylonitrile and butadiene (40:60) and lithium hexafluoroarsenate

A technique for separating cationic and anionic constituents of the ionic conductivity of amorphous solid polymer electrolytes in the region of low salt concentrations is proposed. The technique employs model equations for separately describing transport of cations and anions that differently interact with the polymer matrix. It is shown that the temperature dependences of the anionic conductivity obey the Vogel-Tamman-Fulcher equation and those of the cationic conductivity, the Miyamoto-Shibayama equation. By separating the overall ionic conductivity into constituents, cationic transport numbers are evaluated in broad ranges of salt concentrations and temperatures in the system comprising a copolymer of acrylonitrile and butadiene (40:60) and lithium hexafluoroarsenate. At nearly ambient temperatures the anionic constituent is predominant. Two different cation transport mechanisms are established at elevated temperatures.     

New lithium salts in electrolytes for lithium-ion batteries (Review)

The properties of electrolyte systems based on standard nonaqueous solvent composed of a mixture of dialkyl and alkylene carbonates and new commercially available lithium salts potentially capable of being an alternative to thermally unstable and chemically active lithium hexafluorophosphate LiPF₆ in the mass production of lithium-ion rechargeable batteries are surveyed. The advantages and drawbacks of electrolytes containing lithium salts alternative to LiPF₆ are discussed. The real prospects of substitution for LiPF₆ in electrolyte solutions aimed at improving the functional characteristics of lithium-ion batteries are assessed. Special attention is drawn to the efficient use of new lithium salts in the cells with electrodes based on materials predominantly used in the current mass production of lithium-ion batteries: grafitic carbon (negative electrode), LiCoO₂, LiMn₂O₄, LiFePO₄, and also solid solutions isostructural to lithium cobaltate with the general composition LiMO₂ (M = Co, Mn, Ni, Al) (positive electrode).     

Ab initio calculation of the structure and optical properties of lead oxyhalides Pb<Subscript>3</Subscript>O<Subscript>2</Subscript><Emphasis Type="Italic">X</Emphasis><Subscript>2</Subscript> (<Emphasis Type="Italic">X</Emphasis> = Cl,Br, I)

Using ab initio methods, we obtained information on the crystal structure, calculated the phonon spectra, and determined the optical properties of oxyhalides Pb₃O₂Br₂ and Pb₃O₂I₂. A compound of Pb₃O₂Br₂ is synthesized, and its phonon spectra are recorded. The experimentally observed vibrational bands are assigned. A comparative analysis of the crystal lattice parameters, the phonon spectra, and the anisotropy parameters of lead oxyhalides Pb₃O₂ X ₂ (X = Cl, Br, I) is performed.     

Deterministic Quadrature Formulas for SDEs Based on Simplified Weak Itô–Taylor Steps

We study the problem of approximating the expected value \({\mathbb E}f(X(1))\) of a function f of the solution X of a d-dimensional system of stochastic differential equations (SDE) at time point 1 based on finitely many evaluations of the coefficients of the SDE, the integrand f and their derivatives. We present a deterministic algorithm, which produces a quadrature rule by iteratively applying a Markov transition based on the distribution of a simplified weak Itô–Taylor step together with strategies to reduce the diameter and the size of the support of a discrete measure. We essentially assume that the coefficients of the SDE are s-times continuously differentiable and the diffusion coefficient satisfies a uniform non-degeneracy condition and that the integrand f is r-times continuously differentiable. In the case \(r \le (\lfloor s/2 \rfloor - 1) \cdot 2d/(d + 2)\), we almost achieve an error of order \(\min (r, s)/d\) in terms of the computational cost, which is optimal in a worst-case sense.     

Phase formation in near-morphotropic region of the PbZr1 ? xTixO3 system, structural defects, and electromechanical properties of the solid solutions

Ceramics of PbZr_{1 − x} Ti _x O₃ solid solutions were systematically studied in the range 0.37 ≤ x ≤ 0.57. The x-T phase diagram (T = 25°C) is constructed containing in single-phase regions isosymmetric states characterized by different concentration dependences of the structural and electrophysical parameters. There are also regions where these states coexist, with their unit cell volume remaining unchanged. The existence of these states is interpreted in terms of the real (defect) structure of the ceramics. Several reasons are indicated that are responsible for the appearance of the phase states and related to the crystallochemical peculiarities of the solid solutions: the alternate valence of titanium ions; the infinitely adaptive structure of titanium dioxide; and the formation, ordering, and rotation of the planes of crystallographic shear. It is shown that the transition from the rhombohedral to tetragonal phase occurs indirectly, through two intermediate phases with lower symmetry whose appearance is favored by the defects in the solid solutions. Original Russian Text ? L.A. Reznichenko, L.A. Shilkina, O.N. Razumovskaya, E.A. Yaroslavtseva, S.I. Dudkina, O.A. Demchenko, Yu.I. Yurasov, A.A. Esis, I.N. Andryushina, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 5, pp. 958–965.