Optimization of Mass Transfer Processes in the Zone of the Air Electrode of a Fuel Cell with a Solid Polymer Electrolyte

A two-dimensional mathematical model for the transport of reactants in a fuel cell with a solid polymer electrolyte is developed. The model is used for analyzing spatial distributions of the concentration of reactants and current density over the cell. The effect of the catalytic-layer activity, reactant speed, bipolar-plate geometry, thickness and porosity of current collector and/or gas-diffusion sublayer, and the reaction mixture composition on the fuel cell efficiency is estimated theoretically and experimentally.     

Coulomb integrals in Liouville theory and Liouville gravity

The four-point correlation function has been studied in Liouville field theory. If one of the fields is degenerate, such a function is described in terms of Coulomb integrals. Some nontrivial relations for these integrals have been found that can be used to obtain new exact results in conformal field theory. In particular, a four-point correlation function has been calculated in minimal quantum gravity. The result agrees with the results obtained recently by different methods [A. A. Belavin and A. B. Zamolodchikov, JETP Lett. 82, 7 (2005); Theor. Math. Phys. 147, 729 (2006); A. B. Zamolodchikov, Theor. Math. Phys. 142, 183 (2005); I. K. Kostov and V. B. Petkova, Theor. Math. Phys. 146, 108 (2006)]. The text was submitted by the authors in English.     

Transformations of [Au(CN)2]− at the contact with activated carbon surface

We have studied the processes occurring when alkaline aqueous solution of Na[Au(CN)₂] is brought in contact with activated carbon surface. It has been shown that the adsorption of the gold cyanide complex occurs via several independent routes, one of them being accompanied with the partial breakdown of the inner sphere of the compound and free cyanide ions release into the solution. The latter process decreases the gold recovery by aqueous NaOH during the high-temperature (150°C) desorption. A prolonged storage of the adsorbent saturated with [Au(CN)₂]^? in air produces a similar result. The reasons of the observed phenomena have been discussed.     

Construction and testing of the ALICE TRD chambers at LHE,JINR

The current status of construction and testing of Transition Radiation Detectors (TRD) for ALICE at LHE, JINR, is presented. The main purpose of this detector is electron identification at intensive pion background. The whole ALICE TRD system is comprised of 540 wire chambers of total sensitive area ∼750 m². Each chamber consists of drift and amplifying gaps and a radiator. One hundred such TRD chambers will be constructed at LHE, JINR. The text was submitted by the authors in English.     

Current Trends in Laser Separation of Isotopes in Monatomic Vapors

A comparative analysis of the techniques of laser isotope separation in monatomic vapors is presented. The restraints inherent in the conventional isotope separation technique AVLIS (atomic vapor laser isotope separation) are discussed as applied to the large-scale production of various isotopes. The requirements that should be met by the chemical reactions are formulated for the use of these reactions in isotope separation. The photochemical technique was shown to be quite competitive with the AVLIS.     

Explosive ice instability

Explosive ice instability under strong uniaxial compression at high pressures is observed over a wide temperature range from 244 K down to 100 K. The critical dependence of the threshold instability pressure on temperature in the region of expected Ih-II and IX-VI transitions displays features with minima. It is conjectured that explosive instabilities may occur on cosmic bodies such as the Jupiter satellites Europa and Ganymede.     

Study of the reduction of silicon monoxide in arc plasma

The results of study aimed to reveal the existence of kinetic limitations on the reduction of silicon monoxide with methane carbon in arc plasma in relation to the potential use of this process in the proposed advanced technology for manufacturing pure silicon are reported. It was concluded that the amount of silicon monoxide should be two times its stoichiometric amount required for the complete consumption of the methane carbon and there are no kinetic constraints on the process of silicon monoxide reduction over a time of τ = 4–5 ms at atmospheric pressure and a temperature of T = 2240–2350 K.     

Life tests of lithium/fluorocarbon cells

Long-term (15 years) tests of lithium/fluorocarbon cells (Li-CF _x ) are performed using the full-scale and accelerated storage in a wide temperature range. Regularities governing the capacity loss of the cells in different storage modes are discovered. The self-discharge rate constants are determined for different temperatures. A mechanism is proposed, which explains the cell self-discharge by the occurrence of a number of chemical reactions that lead to the loss of active fluorine and the electrode passivation. The activation energy for the self-discharge process is determined     

Terahertz excitation of the higher-order plasmon modes in field-effect transistor arrays with common and separate two-dimensional electron channels

Using a rigorous electrodynamic approach, the spectra of the terahertz response of periodically ordered arrays of field-effect transistors with two-dimensional electron channel were calculated. It was shown that the higher-order plasmon resonances can be excited in such structures at frequencies above 10 THz.