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Norikazu Nishiyama Yong-Rong Dong Tao Zheng Yasuyuki Egashira Korekazu Ueyama 《Journal of membrane science》2006,280(1-2):603-609
Microporous carbon membranes were prepared on an -alumina support by a pyrolysis of cationic tertiary amine/anionic polymer composites. The precursor solutions contain a thermosetting resorcinol/formaldehyde (RF) polymer and a cationic tertiary amine. Three types of cationic tertiary amines with different chain lengths were used, such as tetramethlammonium bromide (TMAB), tetrapropylammonium bromide (TPAB) and cetyltrimethylammonium bromide (CTAB). A porous structure was produced by a decomposition of the amine and the resulting pores assisted the further gasification of the RF polymer at high temperature. The carbon/alumina membranes have thin and continuous carbon top layers with a thickness of 1 μm. Gas permeation tests were performed using single gases of CO2, O2, N2, CF4, n-C4H10 and i-C4H10, as well as binary mixtures of CH4/n-C4H10 and N2/CF4 at different temperatures between 23 and 150 °C. The carbon membrane prepared using TMAB showed separation factors higher than 650 for the CH4/n-C4H10 mixtures and higher than 8100 for the N2/CF4 mixture. From the permeation of pure gases with different molecular sizes, the pore sizes of the carbon membrane prepared using TMAB, TPAB and CTAB are estimated to be 4.0, 5.0 and larger than 5.5 Å, respectively, indicating that the micropore size of the carbon membranes is controllable by using different amines. 相似文献
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Abstract— The self-sensitized photooxidation of quercetin was not suppressed by superoxide dismutase (SOD), but suppressed by ascorbate. During the suppression of quercetin photooxidation, ascorbate was oxidized. These results suggest the reduction of oxidized quercetin to quercetin by ascorbate. Quercetin photooxidation in the presence of both riboflavin and EDTA was suppressed by SOD by about 90%. The result suggests the participation of O2 - in the photooxidation of quercetin. The participation of O2 - in the quercetin oxidation was confirmed by a xanthine-xanthine oxidase system. Based on these results the physiological and pharmacological functions of quercetin are discussed. 相似文献
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Pinacol-type coupling reaction products presenting a high meso-diastereoselectivity (the ratio dl/meso was 4/96 up to 1/99) were obtained in fair to good yields (24–69%) using several aromatic aldehydes as starting materials and aluminium powder/copper sulfate as catalysts, in water, under reflux conditions. 相似文献
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Takeshi Kakibe Nobuko Yoshimoto Minato Egashira Masayuki Morita 《Electrochemistry communications》2010,12(11):1630-1633
A series of imidazolium cation-based ionic liquids (ILs) have been synthesized and examined as ionic solvents for rechargeable magnesium batteries. The electrolyte solutions consist of these ILs dissolving methylmagnesium bromide with tetrahydrofuran (MeMgBr/THF). The chemical structure of imidazolium cation much influenced the ionic conductivity and the electrochemical window of the system. A reversible process of cathodic deposition and anodic dissolution of magnesium has been successfully achieved at room temperature. The highest value of anodic peak current for magnesium dissolution was obtained in an optimized-structure IL with allyl and methoxyethyl groups as the substituents. 相似文献
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One of the challenges of cellular automaton research is finding models with a low complexity and at the same time a rich dynamics. A measure of low complexity is the number of states in the model and the number of transition rules to switch between those states. In this paper, we propose a 2-dimensional 2-state cellular automaton that-though governed by a single simple transition rule-has a sufficiently rich dynamics to be computationally universal. According to the transition rule, a cell’s state is determined by the sum of the states of the cells at orthogonal or diagonal distances one or two from the cell (distance-2 Moore neighbourhood), but not by the previous state of the cell itself. Notwithstanding its simplicity, this model is able to generate a great variety of patterns, including several types of stable configurations, oscillators and patterns that move over cellular space (gliders). We prove the computational universality of the model by constructing a universal set of logic gates (NOT and AND) from these patterns. A key element in this proof is the shifting of phases and positions of signals such that they meet the input requirements of the logic gates. Similarities of the model with classical spin systems are also discussed. 相似文献
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Shuntaro Mataka Kouichiro Shigaki Tsuyoshi Sawada Yoshihara Mitoma Masahiko Taniguchi Thies Thiemann Kazuya Ohga Naoyoshi Egashira 《Angewandte Chemie (International ed. in English)》1998,37(18):2532-2534
Through clever bridging of orthocyclophanes (in this case by acetalization), molecules such as 1 can be formed with four benzene rings in a stacked face-to-face arrangement. UV/Vis spectroscopic and electrochemical properties of 1 are governed by π–π through-space interactions within the molecule. 相似文献
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H. Akagi H. Ohba K. Yokoyama A. Yokoyama K. Egashira Y. Fujimura 《Applied physics. B, Lasers and optics》2009,95(1):17-21
We have proposed a laser isotope separation method, utilizing rotational coherence of a simple molecule. In the scheme, photoexcited
molecules are isotopically separated by difference of rotational period between them. To illustrate this method, two-pulse
photodissociation of mixed 79Br2/81Br2 isotopes has been investigated theoretically. The photodissociation probabilities of 79Br2 and 81Br2 have been calculated as functions of time delay between the photoexcitation and dissociation laser pulses. We have demonstrated
that isotope enrichment factor of 79Br relative to 81Br can be changed from 0.34 to 1.8, by simply changing the time delay only by 0.2 ns. Additionally, we have shown that this
method is effective for heavy isotopes, based on mass dependence of the isotope enrichment factor. 相似文献