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排序方式: 共有387条查询结果,搜索用时 31 毫秒
181.
We investigated a novel oxidation reaction with surface-oxygen and lattice-oxygen induced using a non-equilibrium electric discharge at ambient temperature. We employed MgO, ZrO2, and TiO2 for this novel reaction. Methane was oxidized easily and converted into H2, CO, and CO2 by the surface-oxygen and lattice-oxygen of oxide with activation of discharge at ambient temperature without gas-phase oxygen. The oxide itself was stable after the reaction. Among these oxides, the tetragonal phase and amorphous phase of ZrO2 showed remarkably high activity for methane oxidation. Consequently, up to 8% of surface and lattice oxygen of the oxide was consumed by methane oxidation induced by electric discharge. The non-equilibrium electric discharge activated both the surface-oxygen and the lattice-oxygen of the oxides and methane molecules in the gas phase. After these reactions, the oxide surface vacant sites were recovered partially through steam post-treatment. Hydrogen formed simultaneously with steam decomposition. Other reactions were also studied by changing the reaction gas: methane into carbon monoxide, carbon monoxide with oxygen, and carbon monoxide with steam. Furthermore, the correlation of reactivity between the feed gas and surface oxygen was studied. Emission spectra under a CH4 atmosphere with electric discharge showed complex peaks caused by carbon monoxide formation at 280-500 nm at 0-4 min, suggesting that surface oxygen on oxides was probably consumed within 4 min from the start of the reaction. 相似文献
182.
M. Machida T. Kano T. Koyama M. Kato T. Ishida 《Journal of Low Temperature Physics》2008,151(1-2):58-63
We perform large-scale numerical simulations on the non-equilibrium superconducting dynamics after a neutron capture at the
superconducting transition edge in MgB2 by solving the time-dependent Ginzburg-Landau equation coupled with the Maxwell and the heat diffusion equations. The simulations
are carried out under the current-biased condition in order to explain experimental results made in the JAEA reactor JRR-3,
and the time scale of the obtained voltage signal is found to be almost consistent with the experiments. Moreover, the time
evolution of the voltage signal is connected with that of the spatial profile of the superconducting order parameter.
相似文献
183.
SMKT (salt-mediated killer toxin), a killer toxin produced by the halotolerant yeast, Pichia farinosa, kills yeasts of several genera, including Saccharomyces cerevisiae. To elucidate the killing mechanism of SMKT, we examined the interaction of SMKT with membranes using liposomes. Leakage of calcein from calcein-entrapped liposomes was observed in the presence of SMKT. Destruction of liposomes was observed by dark-field microscopy. Comparison of intact S. cerevisiae cells with SMKT-treated cells by dark-field microscopy indicated that the spherical cell membrane is disrupted by SMKT. Using sodium carbonate extraction, we obtained direct evidence for the first time that SMKT is associated with the membrane of sensitive cells. Our results indicate that SMKT kills sensitive S. cerevisiae by interacting with the yeast cell membrane. 相似文献
184.
Koichi Onodera Takayo Ogawa Hitoshi Itagaki Hiroshi Machida Satoshi Wada 《Optical Materials》2004,26(4):343
Single crystals of neodymium-doped gadolinium orthovanadate (Nd:GdVO4) were successfully grown by the floating zone method (FZ) with an infrared convergence type heater. These crystal quality and optical properties are sufficient for application to a laser host. Distribution of (Nd/Nd + Gd) concentration by 50 mm in the growth direction was 0.20 ± 0.02 against a target concentration of 0.20. Distribution of extinction ratio at 633 nm by 50 mm in the growth direction was 51 ± 2 dB. Laser performance for these crystals with a-cut were measured. The maximum slope efficiency was 65% and the maximum output power was 3.4 W with continuous wave at 808 nm. 相似文献
185.
Recentemploymentofcommunicationdevices ,(e .g .,mobiletelephones ,intelligenttransportsys tems ,electronictollcollectionsystems ,localareanet worksystemsandradarsystems)hasrapidlyexpand ed .Therefore ,seriouselectromagneticinterference(EMI)problemshaveworsened .Concernfortheseproblemshaspromptedthestudyofelectromagneticwaveabsorbingmaterialswithanti electromagneticin terferencecoatings ,self concealingtechnologyandmicrowavedarkroomsforthecivilandmilitaryapplica tions .Formagneticelectromagnet… 相似文献
186.
187.
The reaction between hydrogen and NO was studied over 1 wt.% Pd supported on NOx-sorbing material, MnOx–CeO2, at low temperatures. The result of pulse mode reactions suggest that NOx adsorbed as nitrate and/or nitrite on MnOx–CeO2 was reduced by hydrogen, which was spilt-over from Pd catalyst. The NOx storage and reduction (NSR) cycles were carried out over Pd/MnOx–CeO2 in a conventional flow reactor at 150 °C. In a storage step, NO was removed by the oxidative adsorption from a stream of 0.04–0.08% NO, 5–10% O2, and He balance. This was followed by a reducing step, where a stream of 1% H2/He was supplied to ensure the conversion of nitrate/nitrite to N2 and thus restore the adsorbability. It was revealed that the NSR cycle is much more suitable for the H2–deNOx process in excess O2, compared to a conventional steady state reaction mode. 相似文献
188.
Transport Properties of Hybrids with Ferromagnetic MnAs Nanoclusters and Their Potential for New Magnetoelectronic Devices
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Granular hybrid structures containing ferromagnetic nanoclusters embedded in a semiconducting matrix are an interesting class of materials as their properties can be tuned in a wide range. Hybrids are a promising alternative to dilute magnetic semiconductors in the field of spintronics and magnetoelectronics, because the nanoclusters can show ferromagnetic behavior even at room temperature. In this review, it is focused on the rather well investigated dilute magnetic semiconductor (Ga,Mn)As with MnAs inclusions. Different preparation methods are presented which were developed over the last two decades in order to obtain MnAs nanoclusters in the semiconducting matrix and to tune the structural and magnetic properties of these clusters. Recent results on the influence of the nanoclusters on the hybrids' transport properties as well as first approaches to use hybrids with a random nanocluster distribution in new spintronic devices are discussed. In addition, the perspective of using single MnAs nanoclusters as well as ordered arrangements of a few nanoclusters in new planar magnetoelectronic devices is illustrated. 相似文献
189.
Preliminary study on sustained arc due to plasma excited by hypervelocity impact of space debris on the solar array coupon 总被引:1,自引:0,他引:1
T. Harano Y. Machida S. Fukushige T. Koura S. Hosoda M. Cho Y. Akahoshi 《International Journal of Impact Engineering》2006,33(1-12):326-334
Recently, solar array has become higher in potential and larger in capacitance. Therefore, possibility of collision between space debris and enlarged solar array has been pointed out. Many debris and dust impacts were confirmed on fuselage of the retrieved satellite space flyer unit (SFU) and solar array paddle of satellite Eureca. If space debris collides with the solar array of an orbiting satellite, it may cause generation of high-density plasma by debris impact-induced dielectric breakdown of satellite component and the phenomenon called discharge. This discharge short circuits the solar array and current will not flow into pay load of the satellite. And the very worst event by this discharge is the operational end of the satellite. However, any events of discharge phenomenon by debris impact cannot be yet confirmed. But we cannot ignore such possibility of discharge by debris impact. The purpose of the present paper is to investigate discharge condition due to debris impact which yields us reduction of electric power of solar array, and to reduce influence of the impact on satellite missions. In this study, a solar array coupon was tested under hypervelocity impact in which a projectile was launched by a two-stage light gas gun installed in Kyushu Institute of Technology (KIT). As a result, we verified discharge event in the hypervelocity impact ground test. 相似文献
190.
Nobuhara H. Tanaka K. Yamamoto T. Machida T. Fujii T. Wakao K. 《Photonics Technology Letters, IEEE》1993,5(9):961-962
We investigated the influence of the band gap wavelength of barrier layers and separate confinement heterostructure (SCH) layers λSCH on the high-temperature operation of InGaAs/InGaAsP compressive-strained quantum-well (QW) lasers. The optimum λSCH was 1.2 μm, at which carriers were sufficiently confined into quantum wells. The QW laser with λSCH = 1.2 μm exhibited low threshold currents of 2.3 mA at 20°C and 9.7 mA at 100°C and CW lasing up to 150°C 相似文献