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排序方式: 共有553条查询结果,搜索用时 15 毫秒
81.
Lee S Teshima K Mori C Suzuki S Yubuta K Endo M Shishido T Oishi S 《Journal of nanoscience and nanotechnology》2012,12(2):1530-1534
Unique Ni compound nanocrystals were successfully grown on carbon nanotubes (CNTs) by cooling a mixed chloride flux. Cup-stacked CNTs (CSCNTs) were used as the nanocarbon materials because of their structural features. The grown nanocrystals had a nanosheet structure, which was densely assembled and had a ribbon-like morphology. Therefore, the nanocrystal/CSCNT composites were expected to have a highly active surface area for the catalyst composites. The selected area electron diffraction pattern and the related radial intensity profiles indicated that the grown nanocrystals were Ni(OH)2. When the pristine CSCNTs were used as a starting material, the formation efficiency of the nanocrystal/CSCNT composites decreased because the pristine CSCNTs were not dispersed in the KCl-LiCl flux. Therefore, functionalization of the CSCNTs was carried out with VUV light irradiation. The dispersibility of the VUV light-treated CSCNTs increased in the KCl-LiCl flux in comparison with the pristine CSCNTs because oxygen-containing functional groups, such as -COOH and -CO, were introduced onto the surfaces of the CSCNTs. 相似文献
82.
Yasushi Abe Kunio Matsubara Kiyoaki Sasagawa Kouki Matsuse 《IEEJ Transactions on Electrical and Electronic Engineering》2008,3(1):113-119
This paper presents a medium‐voltage inverter applying series connected general‐purpose 1.2 kV insulated gate bipolar transistors (IGBTs) as a switching device to achieve low switching losses compared to inverters applying high‐voltage IGBTs with over 3 kV rating. Gate signal synchronization, which is essential to keep the balance of collector‐emitter voltages across the IGBTs, is achieved by magnetically coupling all gate lines using a simple two‐windings transformer. In order to obtain better voltage balancing, influence of stray capacitance distribution associated with an insulating substrate in a two‐in‐one IGBT module on the voltage sharing is investigated, and an optimized layout of heat sinks for the IGBT modules is proposed. To validate some performances concerning the device losses and the voltage sharing, a 170 kVA inverter based on three 1.2 kV IGBTs connected in series is built and evaluated. The experimental results are shown. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
83.
Recently thermal utilizations of sewage sludge, especially pyrolysis and gasification, are regarded as promising technologies due to efficient utilization of fuel gas. In this study, characteristics of tar and NOx precursors were investigated during the pyrolysis of sewage sludge. Moreover, absorption performance for tar and NOx precursors were also studied by using four kinds of scrubbing mediums: cooking oil, diesel oil, BDF and water. The results showed that nitrogenous light PAHs were the major components of nitrogenous tar produced from the pyrolysis of sewage sludge. As for gravimetric tar and major nitrogenous tar compounds removal, cooking oil was the most suitable absorbent. With respect to NOx precursors, it was concluded that HCN, sharing of about 39.5% of total nitrogen of the sewage sludge, was the main NOx precursor gas whereas NH3 content could be neglected. Absorption capacity of hydrophobic scrubbing mediums against NOx precursor gases could be arranged as followed: diesel oil > cooking oil > BDF. 相似文献
84.
1100 kV气体绝缘双断口断路器的开发与产品化 总被引:1,自引:0,他引:1
开发了一种用于气体绝缘组合电器(GIS)的1100kV50kASF6气体双断口断路器(GCB)。研究了这种断路器的各种特性,并成功完成了在绝缘、开断和机械性能等方面的型式试验。实现了GCB的小型化和轻量化。这种新开发的GCB已应用在中国特高压交流示范工程的GIS中,并已于2009年年初投入使用。 相似文献
85.
Bulk glass having a calcium-mica composition (Ca0.5Mg3AlSi3O10F2) is homogeneous glass. The crystallization mechanism of the mica is surface crystallization and transparency is lost completely when crystallization occurs on the surface. In this study, by decreasing SiO2 and increasing CaO and Al2O3 from the chemical composition of Ca0.5Mg3AlSi3O10F2, and moreover by replacing a small amount of K2O instead of CaO, the phase separation appears in the glasses. Because of this phase separation, the mica begins to be crystallized not only on the surface but also in the bulk at lower temperatures. Consequently, the novel transparent machinable mica glass-ceramic can be obtained by heating the glasses having the chemical composition of Ca0.6Mg3Al1.2Si2.8O10F2 and K0.01Ca0.595Mg3Al1.2Si2.8O10F2. As a larger amount of calcium-mica is separated, the bending strength decreases and the fracture toughness increases. Furthermore, by replacing K+ ion instead of Ca2+ ion in the interlayer of calcium-mica, the interlayer bonding strength becomes high, resulting in the increase of the bending strength. 相似文献
86.
Influences of supersaturation in a tetraethyl orthotitanate (TEOT) solution on the degree of crystallinity of product particles in the case of a hydrolysis reaction of TEOT were indicated and the crystallization phenomena of anatase titanium dioxide (TiO2) were discussed. Changes in saturation ratios with experimental durations were examined for the various amount of acetylacetone added into a TEOT solution. At the initial stages of TEOT hydrolysis operations, the degree of crystallinity of product particles was lower for the longer hydrolysis durations but the degrees became almost constant in the later stages of TEOT hydrolysis operations, although the supersaturation of titanium oxide in a TEOT solution was remained. Rapid increase in supersaturation of titanium oxide in a TEOT solution and consequent nucleation of amorphous titanium oxide would be restrained by addition of acetylacetone into a TEOT solution because the concentrations of titanium oxide in a saturated TEOT solution increased with the amount of acetylacetone. 相似文献
87.
Suzuki S Teshima K Lee S Yubuta K Ishizaki T Shishido T Oishi S 《Journal of nanoscience and nanotechnology》2011,11(7):6335-6340
Carbon nanotubes (CNTs) are promising catalyst supports for fuel cell applications. Metal oxide/CNT nanocomposites are also being studied for dye-sensitized solar-cell, photocatalyst, and sensor applications. The fabrication of nanocomposites consisting of highly crystalline NbOx nanotubes and cup-stacked carbon nanotubes (CSCNTs) is reported herein. The CSCNTs were selected for the carbon materials because of their distinctive structure. The CSCNTs were photochemically treated with vacuum ultraviolet light, which increased the amount of oxygen-containing functional groups therein. NbOx nanotubes with no defects were successfully prepared with the chemical treatment of highly crystalline, layered, flux-grown K4Nb6O17 crystals. First, K4Nb6O17 crystals were grown from a KCl flux at a holding temperature of 800 degrees C. Next, NbOx nanosheets were prepared from the layered K4Nb6O17 crystals via a two-step exfoliation process, which consists of proton exchange in an acid solution and intercalation of the tetrabutylammonium ions. The NbOx nanosheets were rolled up into nanotubes with diameters of about 20 nm and lengths of 100-500 nm on the surfaces of the CSCNTs; thus, unique and complex NbOx/CSCNT nanocomposites were successfully fabricated. 相似文献
88.
Application of microbial genes to recalcitrant biomass utilization and environmental conservation 总被引:3,自引:0,他引:3
Recent papers concerning the application of microbial genes to recalcitrant biomass utilization and environmental conservation are reviewed. Microbial genes have been integrated and expressed in plants and microorganisms. When cellulose-degrading enzyme genes are expressed in rice plants, the transgenic plants exhibit swollen cell walls which increases the digestibility of rice straw in the rumen. When genes encoding aromatic compound-degrading enzymes are expressed in plants, it is expected that aromatic compounds contaminating soil would be degraded during the growth of the transgenic plants. The former transgenic plants are utilized as feed and the latter for phytoremediation. Dockerin and cohesin interactions occurring in the cellulase complex, cellulosome, are applied to the construction of artificial enzyme complexes and protein purification by expressing the genes in transformed bacteria and/or silkworms, respectively. In the case of the forced expression of bacterial genes encoding chitinase and/or hydrogenase in the wild-type bacteria, chitin degradation and hydrogen gas production in the transformed bacteria occur at much higher rates than in the wild type. 相似文献
89.
90.
We report here a simple method to identify the ‘emerging topics’ in life sciences. First, the keywords selected from MeSH
terms on PubMed by filtering the terms based on their increment rate of the appearance, and, then, were sorted into groups
dealing with the same topics by ‘co-word’ analysis. These topics were defined as ‘emerging topics’. The survey of the emerging
keywords with high increment rates of appearance between 1972 to 2006 showed that emerging topics changed dramatically year
by year, and that the major shift of the topics occurred in the late 90s; the topics that cover technical and conceptual aspects
in molecular biology to the more systematic ‘-omics’-related and nanoscience-related aspects. We further investigated trends
in emerging topics within various sub-fields in the life sciences. 相似文献