Double-exciton component of the cyclotron spin-flip mode in a quantum Hall ferromagnet

We report on the calculation of the cyclotron spin-flip excitation (CSFE) in a spin-polarized quantum Hall system at unit filling. This mode has a double-exciton component which contributes to the CSFE correlation energy but can not be found by means of a mean field approach. The result is compared with available experimental data.Comment: 9 pages, 2 figure

Impact of Cooling Character on Structure and CTE of Cast Invar Alloy Made From Secondary Raw Materials

Metallography analysis of invar alloys made from secondary raw materials and crystallized with different cooling rates has been carried out. The study has demonstrated that velocity of crystallization has an impact on the dispersity of graphite. The higher velocity of cooling, the more dispersive graphite is. The volume percentage of graphite in alloy, crystallized with high cooling rate, is lower than compared with low cooling rate. Crystallization with low cooling rate leads to the reduction of the amount of carbon into g-phase. The coefficient of thermal expansion is basically depends on the amount of carbon into g-phase. Keywords: invar, alloying, carbon

Sonozonation (sonication/ozonation) for the degradation of organic contaminants - A review.

Abstract Ozonation (OZ) is an important advanced oxidation process to purify water and wastewater. Because of the lower solubility and instability of ozone (O3), selective oxidation and dependence on pH value, the industrial applications of OZ have been hindered by the following disadvantages: incomplete removal of pollutants, lower mineralization efficiency and the formation of toxic by-products. Meanwhile, OZ seems to have higher processing costs than other technologies. To improve the treatment efficiency and O3 utilization, several combined processes, such as H2O2/O3, UV/O3, and Cavitation/O3, have been explored, while the combined method of ultrasonication (US) with OZ is a promising treatment technology with a complex physicochemical mechanism. In US alone, the sonolysis of water molecules can produce more powerful unselective oxidant hydroxyl radicals ( OH), and directly cause the sonochemical pyrolysis of volatile pollutants. In US/OZ, US can promote the mass transfer of O3, and also drive the chemical conversion of O3 to enhance the formation of OH. Various layouts of US/OZ devices and the interactive effects of US/OZ (synergism or antagonism) on the degradation of various organics are illustrated in this review. The main factors, including US frequency, pH value, and radical scavengers, significantly affect the mass transfer and decomposition of O3, the formation of OH and H2O2, the degradation rates of organics and the removal efficiencies of COD and TOC (mineralization). As a result, US can significantly increase the yield of OH, thereby improving the degradation efficiency and mineralization of refractory organics. However, US also enhances the decomposition of ozone, thereby reducing the concentration of O3 in water and impairing the efficiency of selective oxidation with O3 molecules

Influence of Silicon on Temperature Dependence of Thermal Conductivity of Al–Si–Fe Alloys

Temperature dependence analysis of thermal conductivity was carried out for series of aluminum alloys with 1% Fe (mass%) and different content of silicon starting from 0% to 6% (mass%). It is shown that the best alloy for heat exchange applications is alloy with 4% of silicon (mass%). Temperature dependence of thermal conductivity shows the strong decreasing character for silicon-alloyed samples in comparison to pure aluminum. Keywords: aluminum–silicon alloys, thermal conductivity, heat exchange, iron, cast alloys, structure, temperatur

Influence of Silicon on Thermal Conductivity at Room Temperature of Al–Si–Fe Alloys

The analysis of densities and thermal conductivities has been performed for cast experimentally made aluminum alloys containing different content of silicon starting from 0% to 12% (mass%). All alloys have been additionally supplemented by iron up to 1% mass for better casting properties. Results have shown a strong tendency of decrease in the thermal conductivity with increasing silicon content. The same character is found for densities behavior. Keywords: aluminum-silicon alloys, thermal conductivity, heat exchange, iron, cast alloys, structure, temperatur

Dynamics of development of investment processes in Belgorod Region

The present paper investigated results of an analysis of dynamics of changes in the investment structure of Belgorod region on the basis of private and integral indices characterizing the dynamics of structural changes. Structural changes in Belgorod region concerning investment capital were different from corresponding calculated figures in the Central Federal Distric. The revealed differences characterized features of the development in the investment processes and indicated changes in priorities of those investing in the economy of this regio

Towards diluted magnetism in TaAs

Magnetism in Weyl semimetals is desired to investigate the interaction between the magnetic moments and Weyl fermions, e.g. to explore anomalous quantum Hall phenomena. Here we demonstrate that proton irradiation is an effective tool to induce ferromagnetism in the Weyl semimetal TaAs. The intrinsic magnetism is observed with a transition temperature above room temperature. The magnetic moments from d states are found to be localized around Ta atoms. Further, the first-principles calculations indicate that the d states localized on the nearest-neighbor Ta atoms of As vacancy sites are responsible for the observed magnetic moments and the long-ranged magnetic order. The results show the feasibility of inducing ferromagnetism in Weyl semimetals so that they may facilitate the applications of this material in spintronics.Comment: 20 pages, 6 figure