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351.
Density functional theory (DFT) was used to study the electrolyte solution effects on the oxygen reduction reaction (ORR) on Pt(111). To model the acid electrolyte, an H(5)O(2)(+) cluster was used. The vibrational proton oscillation modes for adsorbed H(5)O(2)(+) computed at 1711 and 1010 cm(-1), in addition to OH stretching and H(2)O scissoring modes, agree with experimental vibrational spectra for proton formation on Pt surfaces in ultrahigh vacuum. Using the H(5)O(2)(+) model, protonation of adsorbed species was found to be facile and consistent with the activation barrier of proton transfer in solution. After protonation, OOH dissociates with an activation barrier of 0.22 eV, similar to the barrier for O(2) dissociation. Comparison of the two pathways suggests that O(2) protonation precedes dissociation in the oxygen reduction reaction. Additionally, an OH diffusion step following O protonation inhibits the reaction, which may lead to accumulation of oxygen on the electrode surface. 相似文献
352.
Cecconi D Tessari M Willé DR Zoli M Domenici E Righetti PG Carboni L 《Electrophoresis》2008,29(7):1525-1533
Nicotine dependence is known to induce long‐term neural adaptations in brain. The purpose of this study was to verify whether specific protein patterns related to nicotine self‐administration states could also be detected in a peripheral tissue. A serum proteomic analysis was performed by 2‐DE on samples taken at six time points: N, naïve; P, priming; S, self‐administration; W, withdrawal; E, extinction; R, relapse. After image analysis, spot volume values were submitted to a principal component analysis and relevant comparisons were selected. In N versus S; S versus W; E versus R; S versus R and S versus E comparisons a clear separation between groups could be observed, suggesting that each self‐administration state correlates with a specific protein expression pattern. Partial least squares discriminant analysis was adopted to rank proteins by the contribution to the overall separation. A number of spots were identified; among them, C reactive protein and haemopexin displayed a significant reduction after nicotine administration; two haemopexin isoforms were decreased in the S state and antithrombin III was increased in the E phase. This study showed that specific protein patterns related to the nicotine self‐administration states exist in serum. Further development of this approach may provide biomarkers to assess dependence states of drug‐taking individuals. 相似文献
353.
Uzma Shaheen Terence W. Turney Kei Saito Will P. Gates Antonio F. Patti 《Journal of polymer science. Part A, Polymer chemistry》2016,54(15):2421-2429
Nanocomposites of sodium smectite with polyether‐ and polystyrene‐containing pendant cyclic carbonates offer a novel approach to improving hydraulic barrier properties of Na‐smectite liners to saline leachates. The cyclic carbonate polyethers were prepared by cationic ring opening polymerization of a cyclic carbonate‐containing epoxide, whilst polystyrene polymers having pendant cyclic carbonate groups were obtained from radical photopolymerization of styrene. Na‐smectite nanocomposites of these polymers were formed via clay in situ polymerization and solution intercalation methods. X‐ray diffraction (XRD) and FT‐IR analysis confirmed that the polyether can be intercalated within the layers of smectite via in situ as well as solution intercalation of the pre‐formed polymer. The cyclic carbonate polyether nanocomposite was more resistant to leaching in 3M aqueous sodium chloride than its respective cyclic carbonate. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2421–2429 相似文献
354.
α‐boron is the most simple structure of all boron modifications having one B12 icosahedron per (rhombohedral) unit cell. The conventional, free atom crystal structure refinement with R = 6.2% indicates considerable charge redistribution into covalent bonding. In a high order‐low order and multipole refinement the R value could be reduced to 1.19%. The ensuing deformation difference density maps reveal bonding between the boron atoms, in the icosahedra and between the icosahedra. 相似文献
355.
Marijke WA de Backer Maike AD Brans Mieneke CM Luijendijk Keith M Garner Dianne MA van den Heuvel R Jeroen Pasterkamp Roger AH Adan 《BMC neuroscience》2010,11(1):94
Background
Multiple neuropeptides, sometimes with opposing functions, can be produced from one precursor gene. To study the roles of the different neuropeptides encoded by one large precursor we developed a method to overexpress minigenes and establish local secretion. 相似文献356.
Ostwald Cohen Kohlrausch Heydweiller van't Hoff A. Naumann A. Rücker Arrhenius Walker Shields J. Walker E. Aston C. Kullgren Bredig Fraenkel W. E. Pawloff D. G. Gerassimoff Seth E. Moody R. W. Wood Will Koelichen M. Le Blanc K. Novotny Gernez H. Goldschmidt O. Girard Hantzsch Sebald G. Wiedemann B. E. Moore Dibbits W. Müller und A. Birnbaum 《Fresenius' Journal of Analytical Chemistry》1907,46(2-3):159-165
Ohne Zusammenfassung 相似文献
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