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21.
Kazunori Yamamoto Takatsugu Wakahara Takeshi Akasaka 《Progress in Nuclear Energy》2005,47(1-4):616-623
A carbon nanoencapsulate has a polyhedral outer shell of nested, concentric layers of carbon. The shell defines an internal cavity where a metal is encapsulated. Although the rare-earth carbides readily hydrolyze in moist air, the carbides in these carbon shells did not degrade after exposure to air for considerable lengths of time. This means that the carbide particle is physically enclosed within the carbon cavity completely, and the cavity protects it perfectly against attack of water molecules. Considering intrinsic chemical stability of carbon under oxygen free condition, this structure may be a perfect barrier to extremely long-term release of radionuclides. Because encapsulation of LaC2 within carbon nanoparticles increased drastically from by-product to major product, it would be possible to find the optimized condition that complete encapsulation is achieved. Intrinsic stability of carbon and carbon coated waste nanoparticles may provide an improved barrier to radionuclide release by groundwater. 相似文献
22.
Simultaneous extraction by microwave-irradiation and crystallisation were performed in the same pot of solvent of 70% (v/v) aqueous ethanol for isolation of hesperidin from thinned immature fruit peels of Citrus unshiu as refining of Citrus waste biomass. The hesperidin content in immature fruits peels was about 3.2-fold higher than that of mature fruit. After microwave-assisted extraction (MAE), the yield of hesperidin reached 58.6 mg/g, which was comparable to the amount obtained after extraction using DMSO:methanol (1:1, v/v) as a solvent for 30 min at room temperature. Heating temperature and time for isolation of hesperidin crystallites were optimised as 140 °C and 8 min by using response surface methodology. Under this optimal condition, 86.8% (47.7 mg/g) of total hesperidin was isolable by MAE and low-temperature storage (5 °C, 24 h). 相似文献
23.
24.
在Ad hoc网络中,AODV等路由协议在选择路由路径时没有考虑节点的能量,可能造成部分节点的能量过度使用从而导致网络分割等问题。以AODV为基础,提出了一种基于节点剩余能量和网络稳定性的路由算法ECAODV。该算法在路由发现过程中,不仅要综合考虑路径上的节点的剩余能量和路由跳数,而且考虑路径中间节点对网络稳定性的影响。通过仿真验证该算法有较好的性能。 相似文献
25.
Kazunori Komatani Shinichi Ueno Tatsuya Kawahara Hiroshi G. Okuno 《User Modeling and User-Adapted Interaction》2005,15(1-2):169-183
We address the issue of appropriate user modeling to generate cooperative responses to users in spoken dialogue systems. Unlike
previous studies that have focused on a user’s knowledge, we propose more generalized modeling. We specifically set up three
dimensions for user models: the skill level in use of the system, the knowledge level about the target domain, and the degree of urgency. Moreover, the models are automatically derived by decision tree learning using actual dialogue data collected by the system.
We obtained reasonable accuracy in classification for all dimensions. Dialogue strategies based on user modeling were implemented
on the Kyoto City Bus Information System that was developed at our laboratory. Experimental evaluations revealed that the
cooperative responses adapted to each subject type served as good guides for novices without increasing the duration dialogue
lasted for skilled users. 相似文献
26.
Thermodynamic evaluation of Cu–Cu3P system has been conducted by applying subregular solution model with Gibbs energy of Cu3P formation that was newly determined by means of triple Knudsen cell mass spectrometry. Both the calculated vapor pressure of phosphorus and phase diagram of Cu–P system are excellently consistent with the literature data in the composition range of Cu–Cu3P, indicating that there is no significant thermodynamic inconsistency between the present work based on the Gibbs energy of Cu3P formation determined and the literature data. 相似文献
27.
Three samples of LaCoO3 were prepared by two different methods and calcined at 800 or 1000 °C. They had BET areas of 1, 12, and 16 m2/g and all of them showed pure perovskite X-ray diffraction patterns with identical unit cell dimensions. In a series of experiments the oxide, having larger surface area, was stepwise reduced in hydrogen at temperatures between 60 and 500 °C. The XPS spectra, taken at room temperature after evacuation at 400 °C at each reduction level, showed that the surface concentration of Co° was very low up to 300 °C but increased sharply between 300 and 350 °C (9–75%). This concentration further increased to 100% after 10 min reduction at 450 °C, but upon heating in hydrogen for an additional 10 min at 500 °C it decreased again to 75%. In another series of experiments the mixed oxide was reoxidized after each reduction. A fresh sample was reduced to 350 and 400 °C by contacting with hydrogen for 1 hr and evacuated at temperatures between 400 and 500 °C. Both high evacuation temperatures and reduction at 400 °C during 1 hr produced a sharp decrease in Co° surface concentration. These results are consistent with the catalytic behavior of this perovskite reported earlier by E. A. Lombardo et al. (4–7). A model is proposed to interpret the reduction of LaCoO3. 相似文献
28.
Hiromi Nakano Keigo Suzuki Kazunori Kizima 《Journal of the American Ceramic Society》2006,89(4):1461-1464
The thermal behavior of nanoparticles BaTiO3 , prepared by a radio-frequency plasma chemical vapor deposition (RF-plasma CVD) method, was characterized by various analysis methods. The BaCO3 phase was included in the powder as byproducts, which is also observed in hydrothermal BaTiO3 powder. The BaCO3 phase decomposed and disappeared by annealing at 873 K for 30 min. H2 O, N2 , CO2 and H2 , were detected by a thermal desorption spectra measurement from BaTiO3 powder. The annealed powder became well-crystallized particles without grain growth, although as-prepared powder included polycrystalline particles. We successfully observed in-situ grain growth for BaTiO3 nanoparticles by thermal transmission electron microscope. At the initial step of normal grain growth, very fine particles with 40–60 nm diameters started to merge into the larger grains around 1083 K. The migration rate was measured by video images and a grain boundary diffusion coefficient Dgb was calculated. 相似文献
29.
Satoshi Nogami Katsuhiko Minoura Nao Kiminami Yui Kitaura Hiromasa Uchiyama Kazunori Kadota Yuichi Tozuka 《Advanced Powder Technology》2021,32(5):1750-1756
Although curcumin is considered to have various therapeutic effects, its use as a functional food or supplement is restricted owing to its low water solubility and bioavailability. To increase the solubility of curcumin in water, the use of polyvinylpyrrolidone (PVP) and vinylpyrrolidone-vinyl acetate copolymers with a pyrrolidone skeleton was noted to be promising. In particular, the bi-component formulations of curcumin/PVP prepared through spray drying exhibited an amorphous state in powder X-ray diffraction observations and temporally increased the apparent solubility of curcumin to over 5000 times that of untreated curcumin; nevertheless, after 24 h, the solubility decreased owing to the unstable supersaturated state of curcumin. The addition of α-cyclodextrin (α-CyD) in the bi-component curcumin/PVP formulation helped maintain the supersaturated state of curcumin, whereas the addition of β- and γ-CyD led to the collapse of the supersaturated state. The addition of α-CyD can likely help inhibit the nucleation and crystal growth of curcumin, through the interaction among the solubilized units of curcumin/PVP and α-CyD. 相似文献
30.