Hydrodesulphurization of thiophene by coal mineral matter and a cobalt-molybdate catalyst in a pulse reactor

A pulse reactor was used to compare the catalytic activity of a commercial desulphurization catalyst (Nalco 471) and of mineral matter from Western Kentucky coal. Hydrodesulphurization of thiophene, a model coal sulphur compound, was the reaction studied. Mineral matter was obtained from the coal in its least altered state by a low-temperature, oxygen-plasma technique commonly referred to as low-temperature ashing. Conversion is determined from the C₄ gases which are separated in a two-column Chromatographic system. At 748 K it was found that thiophene conversion with mineral matter was 12% of that with the commercial catalyst. Relative activities of hydrogenation of intermediate butenes to butane, the effect of presulphiding, and that of pyridine poisoning were also determined.     

Synthesis of iron-dispersed carbons by pressure pyrolysis of divinylbenzene-vinylferrocene copolymer

Versatile carbons with finely dispersed iron were synthesized by pressure pyrolysis of a copolymer prepared from divinylbenzene and vinylferrocene at temperatures below 680? C and pressures of 125 MPa. The pyrolysis conditions of the copolymer were found to influence the final morphology of carbons to give fibrils, spheres and polyhedra. The resulting carbons contained uniformly fine particles of cementite (Fe₃C) which were less than 30 nm in size, whereas the magnetite was dispersed in the carbon matrix by pressure pyrolysis in the presence of water. Highly dispersed cementite in carbon was found to decompose into metallic iron by further heat treatment above 850? C. Porous spherulitic carbons were also synthesized by heat treatment of magnetite containing carbon spherulites.     

Synthesis and properties of magnetite-dispersed carbon by pressure pyrolysis of divinylbenzene-vinylferrocene with water

Magnetite-dispersed carbon was synthesized by pressure pyrolysis of the divinylbenzene-vinylferrocene system in the presence of water at 125 MPa below 700°C. Supercritical water influenced the phase separation of oligomers formed during the pyrolysis to give carbons with various morphologies, such as spherulitic, coalescing spherulitic and polyhedral carbon, depending upon the concentration of water. Carbon spherulites from 5 to 10 μm diameter dispersed with magnetite particles (<100 nm) were synthesized by pyrolysis of divinylbenzene-5.1 mol% vinylferrocene and 20.0 wt% water at 550°C and 125 MPa. The specific area of magnetite-dispersed carbon synthesized at 600°C and 125 MPa was 92 m²g⁻¹ after heat treatment at 800°C for 1 h. The specific area of the carbon specimen increased with decreasing pyrolysis temperature of the parent copolymers from 700 to 550°C. The Curie temperature of magnetite-dispersed carbon was 585°C. Magnetite dispersed in the carbon matrix was reduced to wüstite during the further heat treatment in vacuum. The saturation magnetization of magnetite-dispersed carbon was 79% of the theoretical value, and changed in proportion to the concentration of iron in the carbon matrix.     

Effect of Partially Substituting Ca with Mischmetal on the Microstructure and Mechanical Properties of Extruded Mg-Al-Ca-Mn-Based Alloys

Mg-2Al-1.2Ca-0.2Mn(at%)-based alloys with Ce-rich mischmetal(MM) substitution of 0–0.6 at% for Ca were hot extruded at 400 °C. The effect of MM substitution on the microstructure and mechanical properties of the extruded alloys was investigated. The as-cast Mg-2Al-1.2Ca-0.2Mn alloy is mainly composed of a-Mg, Mg_2Ca and(Mg,Al)_2Ca phases and Al_8Mn_5 precipitates, whereas the substitution of MM brings about the formation of Al_(11)MM_3, Al_2MM phases and Al_(10)MM_2Mn_7 particles with the absence of (Mg,Al)_2Ca phase. The volume fraction of MM-containing phases increases with increasing MM contents. All of the extruded alloys exhibit bimodal microstructure comprising fine dynamically recrystallized grains with almost random orientation and coarse deformed grains with strong basal texture. Dense nanosized planar Al_2Ca and spherical Al–Mn phases precipitate inside the deformed grains. High tensile yield strengths of~ 350 MPa and moderate elongations to failure of 12% are obtained in all extruded alloys; the MM substitution induces negligible difference in the tensile properties at ambient temperature, while the highest MM substitution improves the strength at 180 °C due to the better thermal stability of the fragmented MM-containing phases.     

Adiabatic efficiency and Joule dissipation in supersonic Faraday MHD generator

The adiabatic efficiency of a supersonic Faraday MHD (magnetohydrodynamic) generator and its relation to Joule dissipation in the MHD channel were studied in a shock tube experiment. An adiabatic efficiency of 39.7% was obtained at enthalpy extraction of 8.3%. A dissipation process, which reduces the adiabatic efficiency, is examined by evaluating loading parameters and entropy production caused by Joule dissipation. At low load resistance, large Faraday currents in the channel upstream cause extremely large Joule dissipation in both the main flow and the region near the electrodes. It is confirmed experimentally that a high loading parameter yields a high adiabatic efficiency because Joule dissipation is small throughout the MHD channel. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 47–54, 1999     

Effects of fluid flow on the performance of a subsonic nonequilibrium disk MHD generator

The fluid flow and performance of a nonequilibrium disk MHD generator with subsonic flow are examined by time‐dependent two‐dimensional r–z numerical simulations. It is found that the development of the boundary layer is enhanced with increasing load resistance, as is the case in supersonic generators. The development of the boundary layer affects not only the performance of the generator but the thermal input to it, in contrast to supersonic generators. These facts lead to considerable departures from the performance predicted by a quasi‐one‐dimensional simulation and suggest that two‐dimensional design of the generator channel, taking account of boundary layer development, is necessary in order to assure high performance of a subsonic generator. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 18–25, 2000     

The Transition from Transient Oxide to Protective Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Scale on Fe–Cr–Al Alloys During Heating to 1000 °C

The transition behavior of an Al-rich amorphous oxide layer to an external Al₂O₃ layer on Fe–(4, 24)Cr–(6, 10)Al (at.%) alloys was investigated during heating to 1000 °C at a heating rate of 50 °C/min, by means of in situ high-temperature X-ray diffraction measurement and TEM observation. In the alloy containing 6Al, internal amorphous Al₂O₃ was initially developed below the Al-rich amorphous surface layer. The amorphous internal precipitates transformed to be crystalline and grew laterally with time. The internal precipitates subsequently connected with each other to form a continuous α-Al₂O₃ scale. In the case of 10Al alloy, an Al-rich amorphous layer transitioned to a crystalline α-Al₂O₃ layer from the interface between transient/amorphous layers during heating. The Al₂O₃ scale developed on high Al alloys contained Fe and Cr with relatively higher contents, but that formed on low Al alloy contained low Fe and Cr. The effect of Cr on promoting an external Al₂O₃ scale formation was found to be weaker for alloys with higher Al content compared to the alloys with lower Al content, if Al₂O₃ scale was directly transitioned from the amorphous layer.     

D-阿洛酮糖生产工艺研究进展

D-阿洛酮糖是一种超低能量的稀有单糖,具有独特的生理功能特性,主要通过D-阿洛翻糖3-差向异构酶发酵获得.本文阐述了D-阿洛酮糖生产工艺的研究进展.     

Practical color barrier‐free illumination for deuteranopia using LEDs

Here, we propose a color barrier‐free illumination consisting of white, red, and blue LEDs for people with deuteranopia‐type defects in color perception. Color perceptions of 20 volunteers with normal vision and four examinees of deuteranopia were evaluated by both the Ishihara test for color blindness and the Farnsworth Panel D‐15 test under color barrier‐free illumination. The illumination was comparably effective, not only for discriminating between red and green but also for discrimination of the hues on a color chip continuously. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 218–223, 2015     

The Effect of Cr on the Lifetime of Al-Rich Amorphous Oxide Layer Formed on Fe–Cr–Al Alloys at 650 °C

The oxidation behavior of Fe–6Al with different Cr contents (0–24 at.%) at 650 °C in air was investigated so as to clarify the role of Cr in the oxidation resistance of the Al-rich amorphous oxide layer. The time to breakdown of the Al-rich amorphous layer was found to increase with increasing alloy Cr content. This corresponds to the time to increase the rate of oxidation by formation of Fe₃O₄. Such a beneficial effect of Cr to maintain the protective Al-rich amorphous layer for a longer oxidation time is attributed to the enhancement of outward diffusion flux of Al by positive “cross-term effect” of Cr in the Al- and Cr-depleted zone.