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101.
A fractal approach is adopted to describe the dynamic behavior of a circulating fluidized bed. Two times series, differential pressure fluctuations along the riser height and solids momentum fluctuations along the radial direction, are measured and analyzed in terms of fractal dimensions. The influences of operating conditions and axial/radial positions on the fractal dimension are discussed. Attempts are also made to interpret the flow structure in the bed in terms of the fractal dimension. It is found that fractal analysis can provide a useful tool for understanding the characteristics of gas-solids flow in circulating fluidized beds. 相似文献
102.
Poly[(methyl methacrylate)-co-acrylamide] of various compositions were previously prepared by the radical copolymerization reaction of methyl methacrylate and the acrylamide monomer in a solvent. The copolymers were modified through a resonating salt by the addition reaction of a chlorotitanium-triisopropoxide; the modified resins are called Ti hybrid copolymers. The chemical structure of acrylamide side chain groups in the Ti hybrid copolymers was confirmed by the ash weight after combustion, the characteristic absorption band determined by Fourier transform infrared spectrophotometry (IR) and elementary analysis (EA). The curing temperature and time of the resins were determined from the change in the insoluble resin weight when the extraction was done with a mixture of acetone and methanol using the curing resin samples. The thermal stability of the Ti hybrid copolymers was evaluated using both the thermal-degradation temperature (Tx) measured by thermogravimetric analysis and the thermal degradation at 130 °C for 720 h. The cured resins improved the weight loss of the resins at the Tx, and exhibited a high thermal stability. 相似文献
103.
Koichiro Kato 《应用聚合物科学杂志》1975,19(4):951-957
Polyethylene films were irradiated in air by ultraviolet light. 2,4-Dinitrophenylhydrazine was reacted on the irradiated films. The changes in amounts of carbonyl groups and 2,4-dinitrophenynlhydrazones formed in the films were inferred by comparing their absorptions in the infrared and ultraviolet spectra, respectively. It seems that the contents of carbonyl groups formed in the amorphous regions in the high-density polyethylene films by the irradiation were larger than the contents of carbonyl groups formed in the amorphous regions in the low-density polyethylene films. The decreases in contact angles of water on the high-density polyethylene films by the irradiation were larger than the decreases in the contact angles on the low-density polyethylene films. The amounts of 2,4-dinitrophenylhydrazones formed in the irradiated high-density polyethylene films were less than the amounts of 2,4-dinitrophenylhydrazones formed in the irradiated low-density polyethylene films. 相似文献
104.
Tsugio Sato Kenji Dosaka Toshiaki Yoshioka Akitsugu Okuwaki Kazuo Torii Yoshiro Onodera 《Journal of the American Ceramic Society》1992,75(3):552-556
Amorphous CeO2 –ZrO2 gels were prepared by coprecipitation in ammonia solutions. The onset of crystallization of the gels, from calcining in air, was 420°C, while 200° to 250°C in the presence of water and organic solvents such as methanol and ethanol. The sintering behaviors of CeO2 –ZrO2 powders were sensitive to the crystallizing conditions, since hard agglomerates formed when the precipitated gels were crystallized by normal calcination in air, whereas soft agglomerates formed when they were crystallized in water or organic solvents. CeO2 –ZrO2 powders crystallized in methanol and water at 250°C were sintered to full theoretical density at 1150° and 1400°C, respectively, whereas that crystallized by calcination in air at 450°C was sintered to only 95.2% of theoretical density, even at 1500°C. 相似文献
105.
K. Sakata K. Kato Y. Iwase H. Okada K. Ina Y. Machiguchi 《Journal of chemical ecology》1991,17(1):185-193
Phagostimulant activity of glycerolipids such as digalactosyldiacylglycerol (DGDG), 6-sulfoquinovosyldiacylglycerol (SQDG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), etc., have been examined using the Avicel plate method for three kinds of marine herbivorous gastropods, the abaloneHaliotis discus, the turban shellTurbo cornutus, and the topshellOmphalius pfeifferi. DGDG showed strong activity for all the test animals. SQDG was much less active than the other glycerolipids for abalone. The turban shell and the top shell responded more or less sensitively to all tested glycerolipids at doses of 10–20g/sample zone.Chemical Studies on Phagostimulants for Marine Gastropods. Part VIII. For Part VII, see Sakata et al. (1988a). 相似文献
106.
Poly(p-phenylene terephthalamide) (PPTA) was blended with poly(vinyl chloride) (PVC) by solution-blending method. PPTA was metalated for dissolving in dimethyl sulfoxide. Dimethyl sulfoxide was used as a common solvent. In PPTA/PVC composite, PPTA accelerated the thermal degradation of PVC. PPTA molecules are aggregated as microfibrillar form in PVC matrix. Such microfibrils are dispersed homogeneously in PVC matrix, according to polarizing microscopic observation. The average diameter of the microfibrils becomes smaller in the composite with lower content of PPTA. In the surface region of PPTA microfibrils the intermolecular hydrogen bonds between C? Cl of PVC and N? H of PPTA are formed. Young's modulus and the yield stress at room temperature were higher in the composites than those in PVC. The modulus of the composites was higher, especially at the high temperatures above their glass transition temperatures, than that in PVC. The temperature dependence of modulus can be calculated by using the mechanical model equivalent to the quasi-3-dimensional microfibrillar model which will be approximately applied to the composite structure. It becomes apparent that the modulus of the PPTA microfibrils evaluated by using the mechanical model is higher in the higher molecular weight PPTA. 相似文献
107.
Carbon molecular sieve membranes for gas separation prepared using poly(phenylene oxide) (PPO) as precursor have been examined. The PPO precursor was modified by introducing a trimethylsilyl (TMS) substituent and its effect on the gas transport property of the resulting carbon membrane was examined. TMS-substituted PPO (TMSPPO) was prepared in a high yield by a simple one-step reaction, and its carbon membrane was successfully fabricated. The modification improved the gas permeability of the resulting membrane which also exhibited excellent O2/N2 and CO2/CH4 separation performance comparable to those of polyimide-derived carbon membranes. From the analysis of the microstructure of the TMSPPO carbon membranes, it is believed that the TMS groups improve gas diffusivity by increasing the micropore volume. 相似文献
108.
Fumiaki Kobayashi Toru Ogawa Mitsuo Akabori Yoshio Kato 《Journal of the American Ceramic Society》1995,78(8):2279-2281
Uranium-plutonium nitride is a candidate fuel for fast reactors, but its major drawback is 14 C formation from natural nitrogen. One would probably have to use highly 15 N-enriched nitrogen. A pyrochemical process with molten-salt electroreflning has been proposed as a means to increase the nuclear proliferation resistance of the fuel cycle. Molten-salt electroreflning could also be applied to nitride fuels to make possible the recycling of 15 N. The anodic dissolution behavior of UN in LiCI-KCI melt was studied to provide the basis for a feasibility study of electroreflning of irradiated nitride fuels. 相似文献
109.
Influence of tetrabutyl-, tetrapentyl- and tetraisopentylammonium ions on the reduction of nickel(II) in thiocyanate solutions at the dropping mercury electrode has been investigated. These tetraalkylammonium ions, at their low concentrations, inhibit the reduction of nickel(II). However, at their high concentrations, the strong inhibiting effect disappers with the formation of a new wave corresponding to the reduction of a negatively charged nickel(II) thiocyanate complex, which is stabilized by the formation of ion pair with tetraalkylammonium cation. The variation of the reduction current with tetraalkalylammonium concentration was explained by taking into consideration both the change of the total charge of nickel(II) thocyanate complex involved in the reduction process and the simultaneous adsorption of tetraalkylammonium and thiocyanate ions on the mercury electrode. 相似文献
110.
Momoji Kubo Tsuguo Kubota Changho Jung Minako Ando Satoshi Sakahara Kenji Yajima Kotaro Seki Rodion Belosludov Akira Endou Seiichi Takami Akira Miyamoto 《Catalysis Today》2004,89(4):479-493
Recently, we introduced a concept of combinatorial chemistry to computational chemistry and proposed a new method called “combinatorial computational chemistry”, which enables us to perform a theoretical high-throughput screening of catalysts. In the present paper, we reviewed our recent application of our combinatorial computational chemistry approach to the design of new catalysts for high-quality transportation fuels. By using our combinatorial computational chemistry techniques, we succeeded to predict new catalysts for methanol synthesis and Fischer–Tropsch synthesis. Moreover, we have succeeded in the development of chemical reaction dynamics simulator based on our original tight-binding quantum chemical molecular dynamics method. This program realizes more than 5000 times acceleration compared to the regular first-principles molecular dynamics method. Electronic- and atomic-level information on the catalytic reaction dynamics at reaction temperatures significantly contributes the catalyst design and development. Hence, we also summarized our recent applications of the above quantum chemical molecular dynamics method to the clarification of the methanol synthesis dynamics in this review. 相似文献