Thermoelectric performance of weakly coupled granular materials

We study thermoelectric properties of inhomogeneous nanogranular materials for weak tunneling conductance between the grains, g_t < 1. We calculate the thermopower and figure of merit taking into account the shift of the chemical potential and the asymmetry of the density of states in the vicinity of the Fermi surface. We show that the weak coupling between the grains leads to a high thermopower and low thermal conductivity resulting in relatively high values of the figure of merit on the order of one. We estimate the temperature at which the figure of merit has its maximum value for two- and three-dimensional samples. Our results are applicable for many emerging materials, including artificially self-assembled nanoparticle arrays.Comment: 4 pages, 3 figure

Thermoelectric performance of granular semiconductors

We study thermoelectric properties of granular semiconductors with weak tunneling conductance between the grains, g_t < 1. We calculate the thermopower and figure of merit taking into account the shift of the chemical potential and the asymmetry of the density of states in the vicinity of the Fermi surface due to n- or p-type doping in the Efros-Shklovskii regime for temperatures less than the charging energy. We show that for weakly coupled semiconducting grains the figure of merit is optimized for grain sizes of order 5nm for typical materials and its values can be larger than one. We also study the case of compensated granular semiconductors and show that in this case the thermopower can be still finite, although two to three orders of magnitude smaller than in the uncompensated regime.Comment: 4 pages, 4 figure

Capability assessment for application of clay mixture as barrier material for irradiated zirconium alloy structure elements long-term processing for storage during decommissioning of uranium-graphite nuclear reactors

The radionuclide composition and the activity level of the irradiated zirconium alloy E110, the radionuclide immobilization strength and the retention properties of the mixed clay barrier material with respect to the radionuclides identified in the alloy were investigated to perform the safety assessment of handling structural units of zirconium alloy used for the technological channels in uranium-graphite reactors. The irradiated zirconium alloy waste contained the following activation products:{93m}Nb and the long-lived {94}Nb, {93}Zr radionuclides. Radionuclides of {60}Co, {137}Cs, {90}Sr, and actinides were also present in the alloy. In the course of the runs no leaching of niobium and zirconium isotopes from the E110 alloy was detected. Leach rates were observed merely for {60}Co and {137}Cs present in the deposits formed on the internal surface of technological channels. The radionuclides present were effectively adsorbed by the barrier material. To ensure the localization of radionuclides in case of the radionuclide migration from the irradiated zirconium alloy into the barrier material, the sorption properties were determined of the barrier material used for creating the long-term storage point for the graphite stack from uranium-graphite reactors

The Tunka Experiment: Towards a 1-km^2 Cherenkov EAS Array in the Tunka Valley

The project of an EAS Cherenkov array in the Tunka valley/Siberia with an area of about 1 km^2 is presented. The new array will have a ten times bigger area than the existing Tunka-25 array and will permit a detailed study of the cosmic ray energy spectrum and the mass composition in the energy range from 10^15 to 10^18 eV.Comment: 3 pages, 2 figures, to be published in IJMP

Primary Energy Spectrum and Mass Composition Determined with the Tunka EAS Cherenkov Array

New results of 300 hours of operation of the Tunka array are presented. An improved parametrization of the Cherenkov light lateral distribution function (LDF), based on CORSIKA Monte Carlo simulations and the experiment QUEST, has been used for the reconstruction of EAS parameters. The corrected energy spectrum in the knee region is obtained. The mean depth of the EAS maximum has been derived both from the analysis of LDF steepness and the FWHM of Cerenkov light pulse. The mean mass composition around the knee is estimated.Comment: 3 pages, 3 figures, to be published in IJMP

The Lake Baikal neutrino experiment: selected results

We review the present status of the lake Baikal Neutrino Experiment and present selected physical results gained with the consequetive stages of the stepwise increasing detector: from NT-36 to NT-96. Results cover atmospheric muons, neutrino events, very high energy neutrinos, search for neutrino events from WIMP annihilation, search for magnetic monopoles and environmental studies. We also describe an air Cherenkov array developed for the study of angular resolution of NT-200.Comment: 25 pages, 12 figures. To appear in the Procrrdings of International Conference on Non-Accelerator New Physics, June 28 - July 3, 1999, Dubna, Russi

Antioxidants and Cognitive-Behavioral Therapy in Patients with Functional Dyspepsia

Аim: development of an algorithm for the use of antioxidant cognitive-behavioral therapy in adult patients with functional dyspepsia.Material and methods. The study included 112 adult patients with functional dyspepsia receiving the antioxidant drug Cytoflavin containing succinic acid, inosine, nicotinamide and riboflavin, and cognitive behavioral therapy according to the method of Beck and Jacobson in addition to the main therapy (prokinetics, proton pump inhibitors, psychotropic drugs).Results. Of the total group, 74 patients had an optimal response to the inclusion of an antioxidant and psychotherapy in the treatment regimen (increased quality of life and reduced anxiety) and 38 patients had the insignificant response. It has been established that the main predictors of the successful use of an extended treatment regimen are the patient's disadaptation in relation to the disease, a recent stress factor, the duration of functional dyspepsia, the presence of an overlap syndrome (combination with other functional gastrointestinal disorders).Conclusions. Based on the collection of a small amount of anamnestic information (the duration of functional dyspepsia, the presence of an acute stress factor in the anamnesis), the assessment of the presence of an overlap syndrome and disadaptation in relation to the patient to his illness, the value of the discriminant function is calculated. After comparing it with a threshold, the probability of a positive response to a combination of antioxidant and cognitive-behavioral therapy is estimated. The developed prediction algorithm is valid (sensitivity — 91 %, specificity — 73 %, accuracy — 84.8 %) and allows to optimize the definition of treatment tactics for a patient with functional dyspepsia

IMPROVING THE QUALITY OF NON-FERROUS METAL CONCENTRATES WITH EDDY CURRENT SEPARATION OF CABLE SCRAP

Growth in the amount of waste containing non-ferrous metals leads to environmental pollution. An enormous amount of electrical cable is disposed of as scrap each year. The article shows the possibility of recovering residual copper from aluminum concentrate, obtained from crushed waste electrical cables.Рост количества отходов, содержащих цветные металлы, приводит к загрязнению окружающей среды. Огромное количество электрического кабеля утилизируется в виде лома каждый год. В статье показана возможность извлечения остаточной меди из алюминиевого концентрата, полученного из измельченных отходов электрических кабелей