Current discontinuities on superconducting cosmic strings

The propagation of current perturbations on superconducting cosmic strings is considered. The conditions for the existence of discontinuities similar to shock waves have been found. The formulas relating the string parameters and the discontinuity propagation speed are derived. The current growth law in a shock wave is deduced. The propagation speeds of shock waves with arbitrary amplitudes are calculated. The reason why there are no shock waves in the case of time-like currents (in the “electric” regime) is explained; this is attributable to the shock wave instability with respect to perturbations of the string world sheet.     

Interaction of a bispyrazole-based ligand with metal cations in ethanol

A new ligand based on two pyrazole cycles linked with each other was synthesized. Its interaction with Cu(II), Ni(II), Co(II), Mn(II), Cr(III), Zn(II), and Cd(II) cations in ethanol was studied by the spectrophotometric method.     

On the depth of the storage access function

We consider the synthesis problem for the storage access function, which often appears as a component of integrated circuits and is also used in theoretical investigations. The precise value of the depth of the storage access function depending on n address variables, where 1 ⩽ n ⩽ 5 or n ⩾ 20, is established over the standard basis under the assumption that the conjunction and disjunction gates have the depth 1 and that the negation gates have the depth 0. For the rest of the values of n the upper and the lower bounds for the specified depth are proven.     

Mechanism for Conversion of the Conductivity Type in Arsenic-Doped p-CdxHg1–xTe Subject to Ionic Etching

Based on an analysis of chemical diffusion of mercury in p-Cd _x Hg_1–x Te:As narrow-band solid solutions, a mechanism for conversion of the conductivity type upon ionic etching is suggested. It is shown that the n–p conversion of the conductivity in this case is due to the formation of a donor complex between arsenic in the Te sublattice and an interstitial Hg atom. Moreover, the electron concentration in the converted layer corresponds to the concentration of the implanted arsenic impurity. The theoretical results are confirmed by the experimental investigation of the electron concentration distribution over the n-layer of a p-Cd _x Hg_1–x Te:As epistructure converted upon ionic etching.     

Photocyclization of 2-azido-1-(4-<Emphasis Type="Italic">tert</Emphasis>-butylphenoxy)-9,10-anthraquinone in the presence of substituted phenols

New types of phototransformations in the quinone series, viz., photocyclizations of 1-aryloxy-2-azido-9,10-anthraquinone in the presence of phenols, were studied. The photolysis affords mainly 5H-naphtho[2,3-c]phenoxazine-8,13-diones, in which the nitrogen atom is covalently bound to the phenyl ring of the attached phenol. As a result, complex polycyclic derivatives of phenoxazines were prepared in high yields in one step. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1089–1093, June, 2007.     

Mathematical modelling of actinide extraction equilibria and extraction processes

Progress is reviewed in the authors' works on actinide extraction equilibria (including activity coefficient evaluation from extraction data) and their mathematical modelling (including Tc influence on Pu/U separation).     

Investigation of a dense,chemically reacting plasma by the high-frequency probe potential modulation method

A method is proposed for investigating a chemically reacting plasma by means of an electric probe whose potential is modulated by a high-frequency sinusoidal voltage. The method is based on the use of a numerical solution of the problem of an electric probe introduced under negative potential into a steady-state low-temperature plasma formed in a mixture of chemically reacting molecular gases. The conditions under which the charged particle concentration in the region undisturbed by the probe is constant as a result of equilibrium between the ionization and recombination rates are examined.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 114–119, November–December, 1987.     

Electrochemical properties of photocurable membranes for all-solid-state chemical sensors

The development of ion-selective electrodes with inner solid contact is described using photocurable acrylated polyurethane matrices and electron-ion exchanger (EI), which provides a reversible transition from electrical conductivity in the metal to ionic conductivity in the membrane phase. The application of a photocurable polymer matrix gives the possibility to use modern photolithographic techniques for the formation of all-solid-state chemical sensors. The influence of the polymer matrix and of the preparation of the membrane on the electro-chemical properties of calcium-selective membrane sensors is shown. For carbonate-selective membranes the possibility of improvement of electrochemical characteristics by incorporation of the anionic additive tetrakis (4-chlorophenyl) borate was studied. Received: 14 June 1997 / Revised: 23 September 1997 / Accepted: 9 October 1997