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61.
Jinnouchi R Kodama K Hatanaka T Morimoto Y 《Physical chemistry chemical physics : PCCP》2011,13(47):21070-21083
A first principles-based mean field model was developed for the oxygen reduction reaction (ORR) taking account of the coverage- and material-dependent reversible potentials of the elementary steps. This model was applied to the simulation of single crystal surfaces of Pt, Pt alloy and Pt core-shell catalysts under Ar and O(2) atmospheres. The results are consistent with those shown by past experimental and theoretical studies on surface coverages under Ar atmosphere, the shape of the current-voltage curve for the ORR on Pt(111) and the material-dependence of the ORR activity. This model suggests that the oxygen associative pathway including HO(2)(ads) formation is the main pathway on Pt(111), and that the rate determining step (RDS) is the removal step of O(ads) on Pt(111). This RDS is accelerated on several highly active Pt alloys and core-shell surfaces, and this acceleration decreases the reaction intermediate O(ads). The increase in the partial pressure of O(2)(g) increases the surface coverage with O(ads) and OH(ads), and this coverage increase reduces the apparent reaction order with respect to the partial pressure to less than unity. This model shows details on how the reaction pathway, RDS, surface coverages, Tafel slope, reaction order and material-dependent activity are interrelated. 相似文献
62.
Ryosuke Hyakuna Masayoshi Tsutsumi 《NoDEA : Nonlinear Differential Equations and Applications》2011,18(3):309-327
We consider the Cauchy problem for the nonlinear Schrödinger equations $ \begin{array}{l} iu_t + \triangle u \pm |u|^{p-1}u =0, \qquad x \in \mathbb{R}^d, \quad t \in \mathbb{R} \\ u(x,0)= u_0(x), \qquad x \in \mathbb{R}^d \end{array} $ for 1 < p < 1 + 4/d and prove that there is a ${\rho (p ,d) \in (1,2)}We consider the Cauchy problem for the nonlinear Schr?dinger equations
l iut + \triangle u ±|u|p-1u = 0, x ? \mathbbRd, t ? \mathbbR u(x,0) = u0(x), x ? \mathbbRd \begin{array}{l} iu_t + \triangle u \pm |u|^{p-1}u =0, \qquad x \in \mathbb{R}^d, \quad t \in \mathbb{R} \\ u(x,0)= u_0(x), \qquad x \in \mathbb{R}^d \end{array} 相似文献
63.
Issei Otsuka Ryosuke Sakai Toshifumi Satoh Ryohei Kakuchi Harumi Kaga Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2005,43(23):5855-5863
A poly(phenylacetylene) bearing a polycarbohydrate ionophore as a graft chain (copolymer 4 ) was synthesized by the copolymerization of end‐functionalized (1→6)‐2,5‐anhydro‐3,4‐di‐O‐ethyl‐D ‐glucitol with a 4‐ethynylbenzoyl group (macromonomer 2 ) with phenylacetylene. Copolymer 4 showed a split‐type circular dichroism (CD) in the long absorption region of the conjugated polymer backbone (280–500 nm), and the CD pattern varied in response to external stimuli, such as the solvents and temperature. This suggested that 4 had a predominantly one‐handed helical conformation in the polyacetylene backbone. The CD pattern of 4 was completely inverted by the formation of a complex between the macromolecular ionophore units and the selected metal cations, that is, Ba2+, Pb2+, Sr2+, Na+, and Li+. This suggested that copolymer 4 underwent a helix–helix transition through the host–guest complexation with achiral inorganic metal cations. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5855–5863, 2005 相似文献
64.
It is well known that the determinant of a matrix can only be defined for a square matrix. In this paper, we propose a new definition of the determinant of a rectangular matrix and examine its properties. We apply these properties to squared canonical correlation coefficients, and to squared partial canonical correlation coefficients. The proposed definition of the determinant of a rectangular matrix allows an easy and straightforward decomposition of the likelihood ratio when given sets of variables are partitioned into row block matrices. The last section describes a general theorem on redundancies among variables measured in terms of the likelihood ratio of a partitioned matrix. 相似文献
65.
Shiro Kobayashi Ryosuke Itoh Hidekazu Morii Shun-Ichi Fujikawa Shunsaku Kimura Masashi Ohmae 《Journal of polymer science. Part A, Polymer chemistry》2003,41(22):3541-3548
Hyaluronic acid and chondroitin were successfully synthesized as representative molecules of glucosaminoglycans and galactosaminoglycans found in a glycosaminoglycan family via enzymatic polymerization catalyzed by testicular hyaluronidases. A newly designed N-acetylhyalobiuronate oxazoline derivative with a β-D -glucuronyl-(1→3)-N-acetyl-D -glucosamine disaccharide structure served as a transition-state analogue substrate monomer for the enzyme, giving rise to artificial hyaluronic acid in 52% yields with a number-average molecular weight of 1.35 × 104 through ring-opening polyaddition in a perfect regioselective and stereoselective manner. A novel N-acetylchondrosine oxazoline derivative with a β-D -glucuronyl-(1→3)-N-acetyl-D -galactosamine disaccharide structure also acted as a transition-state analogue substrate monomer for the enzyme, yielding artificial chondroitin in 35% yields with a number-average molecular weight of 2.5 × 103. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3541–3548, 2003 相似文献
66.
Membrane potential is determined by the combination of the properties of ions and of the membrane. There is, therefore, a possibility that the properties of ions can be reflected on the membrane potential more effectively by artificially modifying the membrane properties. In this paper, the membrane is assumed to have no charge but to adsorb cations or anions selectively, and the effect of Langmuir-type adsorption of ions on the membrane potential is investigated theoretically. The variation of the amount of adsorbed ions affects not only the surface potential but also the diffusion potential within the membrane. The membrane potential shows a minimum or a maximum with the variation of the ion concentration in the bulk solution. This phenomenon results from the variation of the amount of ions adsorbed onto the membrane surfaces. Therefore, information on both the adsorption coefficient of a given ion and the amount of saturation of absorption of the ion is obtained from an analysis of the membrane potential. The theory is applied to the analysis of the affinity membrane potential, which can be used for the determination of blood type, and it is shown that the theory is in good agreement with experimental data. 相似文献
67.
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69.
Three novel 22-beta-O-spirostanol oligoglycosides, torvosides J (1), K (2) and L (3) have been isolated from the fruits of Solanum torvum SWARTZ and their chemical structures have been characterized based on the spectroscopic means. They are worth of note as rare 22-beta-O-spirostanol glycosides. 相似文献
70.
Niikura K Kamitani R Kurogochi M Uematsu R Shinohara Y Nakagawa H Deguchi K Monde K Kondo H Nishimura S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(13):3825-3834
We have developed an effective and practical trap-and-release method based on chemoselective ligation of carbohydrates with reactive aminooxyl groups attached to the surface of nanoparticles (referred to as glycoblotting nanoparticles). These glycoblotting nanoparticles were synthesized by UV irradiation of diacetylene-functionalized lipids that contain the aminooxyl group. The glycoblotting nanoparticles captured carbohydrates in aqueous solution under mild conditions and were collected by simple centrifugation. The trapped carbohydrates were effectively released from the nanoparticles under acidic conditions to give pure oligosaccharides. This glycoblotting process reduced the time required for the purification process of carbohydrates to less than 6 h, compared to the several days needed for conventional chromatographic techniques. The oligosaccharides (N-glycan) were released from ovalbumin (glycoprotein) by PNGase F after tryptic digestion. MALDI-TOF mass spectra before purification did not show any significant signals corresponding to N-glycans because these signals were hidden by the large signals of the abundant peptides. However, after purification with the glycoblotting nanoparticles, only signals corresponding to oligosaccharides appeared. We also demonstrated a clear analysis of the oligosaccharides contained in the mice dermis by means of glycoblotting. 相似文献
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