Methane oxidative coupling on the Au/La2O3/CaO catalyst in the presence of hydrogen peroxide

Methane oxidative coupling in the presence of the catalyst 1% Au/5% La₂O₃/CaO and gas-phase initiator hydrogen peroxide at the temperature 700–800°C under normal pressure has been studied. It has been shown that hydrogen peroxide remarkably increases the yield of C₂₊ products without the loss of selectivity. The maximal yield of C₂₊ products under the conditions studied was 27% with the formation of a noticeable quantity of benzene. It has been proposed, that the observed effect is due to hydroxyl radical formation from hydrogen peroxide, which could be essential under definite conditions also in a conventional catalytic methane oxidative coupling.     

High coercivity magnetic multi-wall carbon nanotubes for low-dimensional high-density magnetic recording media

Fe-embedded multi-wall carbon nanotubes (MWCNTs) were fabricated using Fe-catalyst by the chemical deposition method. Microscopic characterizations showed that the well-aligned MWCNTs were ～ 80 mm in length, with outer diameter of 20–50 nm and inner diameter of 10–20 nm. Magnetic properties were characterized in temperatures of 5 K and 305 K, which revealed that the MWCNTs exhibited high coercivity of 2600 Oe at 5 K and 732 Oe at 305 K. These values are much higher than that of bulk iron (～ 0.9 Oe) and Fe/Co/Ni nanoparticles or nano-wire arrays (～ 200–500 Oe) at the room temperature. This high coercivity and the structure of single-domain Fe nanoparticles isolated by anti-ferromagnetic MWCNTs make it a promising candidate for low-dimensional high-density magnetic recording media.     

Wear of Chromium Carbide-Copper Composites with Continuous Phases

A tribological study has been carried out on a new type of carbide-metal composite, in which the two phases form a continuous skeleton microstructure interwoven throughout the body. The composites' resistance to two-body abrasion is evaluated in a pin-on-drum set-up with diamond and SiC abrasive papers. Also sliding wear and friction tests with steel and alumina as counter materials were undertaken. The composites show promising tribological properties, comparable to those of established wear resistant materials. Scanning electron microscopy was used to study the worn surfaces. The implications of the skeleton microstructure on the abrasive wear resistance are discussed on the basis of a wear model for multiphase materials.     

Experimental evaluation of losses in magnetic components for powerconverters

A very versatile experimental method for measuring losses in magnetic components is presented. This is not subject to the bandwidth constraints associated with the direct wattmeter method. The proposed method features accurate measurement of conduction losses, separation of core and conduction losses, measurement at high frequencies, and scale modeling of magnetic components. The experimental measurements are compared with theoretical predictions of components as applicable to certain power electronic converters     

Optimum nonlinear turn-off snubbers: design and application

The optimization of the general turn-off snubber, consisting of a nonlinear saturable snubber capacitor with an energy recovery circuit, is done in terms of minimum total energy loss in the power electronic turn-off circuit. To analyze this nonlinear circuit without a computer simulation, a two-step piecewise-linear approximation of the capacitor's capacitance-voltage curve is presented. Results regarding the total energy loss in the circuit during the switch turn-off indicate that the nonlinear capacitor as a snubber element is superior to the normal linear capacitor even if the ceramic capacitor is used only up to its specified voltage value     

Improving the sensitivity and line edge roughness in inorganic positive electron beam resist

Need for inorganic electron beam resist with higher sensitivity and resolution is indisputable. We have developed such a resist that also shows lower line edge roughness. It is pre-baked at 300 °C. By using 4 kV EB we have delineated 40 nm lines pattern and honeycomb structure Photonic crystal pattern.     

Seasonal variations of pH and electrical conductivity in a snow-firn pack on Glacier No. 1, eastern Tianshan,China

Analyses of pH and electrical conductivity (EC) in surface snow and snow-firn pack samples collected successively in a weekly basis during September 2002 to September 2004 on the east branch of Glacier No. 1, eastern Tianshan, China is presented. pH and EC in surface snow show obvious seasonal variations. pH and EC values are high in spring and early summer, and they are low in late summer; moreover, pH value indicates more and less alkalinity in spring and winter, respectively. In addition, both pH and EC peaks strongly coincide with the corresponding period of greatest NE and ENE wind velocity. After deposition, pH and EC in snow-firn pack display diverse features and seasonal trends, which correlate with snow compaction, dry deposition, precipitation and temperature, and so on. Furthermore, both pH and EC peaks occur above dust layers, and are adjacent to dust layers in some snow-firn packs. This implies that dust layers may have an influence on the elution process of soluble ions. In addition, linear correlation analyses among major chemical species (Na⁺, K⁺, Ca²⁺, Mg²⁺, NH₄⁺, Cl⁻, SO₄²⁻, NO₃⁻, pH and EC) in surface snow indicate that Ca²⁺ is the key ion determining pH and EC in the study area.     

Rural electrification systems based on renewable energy: The social dimensions of an innovative technology

Many areas in rural non-Western regions are installing electrification systems based on renewable energy. Although these projects are usually welcome, they sometimes fail. Explanations for failures often cite technical reasons. In this research, partly based on the results of the SOPRA_RE project, we focus on the users, studying the relationships between technology and society. By analysing potential sources of failures, we identify the root of the problem as how a new technology is received by the local society. In this paper we introduce dimensions that we consider to be especially important in the process of technology integration. We defend the importance of combining the technical outlook with the sociological one, based on the idea that the latter is often indispensable as a complementary element of technical explanations of system failures, which in turn provides a better basis for solving them. We use specific examples to bolster our insistence on the need to achieve convergence between the technical and the sociological outlooks.