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991.
Henryk Bala Martyna Dymek Lidia Adamczyk Krystyna Giza Henryk Drulis 《Journal of Solid State Electrochemistry》2014,18(11):3039-3048
Meticulous analysis of galvanostatic charge/discharge dependencies of the LaNi5-based, powder composite electrode, in terms of determination of characteristic kinetic parameters of hydrogen storage electrode materials working in concentrated alkaline solution has been carried out. A special attention has been paid to the precise determination of charge and discharge times. The cathodic curves reveal their stepwise nature which allows to receive information of hydride material corrosion phenomena and determine the real time of atomic hydrogen absorption. The graphical way of determining of reduction times, based on differential cathodic curves is proposed. The knowledge of hydrogen absorption and desorption times allows to determine hydrogen diffusivity within the tested material with acceptable accuracy. The effect of external pressure (0.5–4 bar) on hydrogen absorption ability of LaNi5-based material is also discussed. The exchange current density of H2O/H2 system distinctly increases with external pressure, at the same time, kind of gas atmosphere (Ar or H2) scarcely affects the exchange current on the LaNi5 electrode. The hydrogen capacity increases when the charge/discharge rate decreases. The reduction times of oxide phases formed during electrode discharge can be a measure of material corrosion rate. It is shown that the rate of LaNi5 corrosion process strongly increases with the electrode cycling. 相似文献
992.
Dr. Yasar Akdogan Dr. Wei Wei Dr. Kuo‐Ying Huang Dr. Yoshiyuki Kageyama Eric W. Danner Dusty R. Miller Nadine R. Martinez Rodriguez Prof. Dr. J. Herbert Waite Prof. Dr. Songi Han 《Angewandte Chemie (International ed. in English)》2014,53(42):11253-11256
Sessile marine mussels must “dry” underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force‐free approach to measuring molecular‐level interaction through surface‐water diffusivity, different mussel foot proteins were found to have different abilities to evict hydration layers from surfaces—a necessary step for adsorption and adhesion. It was anticipated that DOPA would mediate dehydration owing to its efficacy in bioinspired wet adhesion. Instead, hydrophobic side chains were found to be a critical component for protein–surface intimacy. This direct measurement of interfacial water dynamics during force‐free adsorptive interactions at solid surfaces offers guidance for the engineering of wet adhesives and coatings. 相似文献
993.
The First Heteropentanuclear Extended Metal‐Atom Chain: [Ni+Ru25+Ni2+Ni2+(tripyridyldiamido)4(NCS)2]
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Dr. Min‐Jie Huang Dr. Shao‐An Hua Dr. Ming‐Dung Fu Dr. Gin‐Chen Huang Prof. Caixia Yin Chih‐Hung Ko Dr. Ching‐Kuo Kuo Chia‐Hung Hsu Dr. Gene‐Hsiang Lee Kuan‐Yi Ho Dr. Chia‐Hsin Wang Prof. Yaw‐Wen Yang Prof. I‐Chia Chen Prof. Shie‐Ming Peng Prof. Chun‐hsien Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4526-4531
This study develops the first heteropentametal extended metal atom chain (EMAC) in which a string of nickel cores is incorporated with a diruthenium unit to tune the molecular properties. Spectroscopic, crystallographic, and magnetic characterizations show the formation of a fully delocalized Ru25+ unit. This [Ru2]‐containing EMAC exhibits single‐molecule conductance four‐fold superior to that of the pentanickel complex and results in features of negative differential resistance (NDR), which are unobserved in analogues of pentanickel and pentaruthenium EMACs. A plausible mechanism for the NDR behavior is proposed for this diruthenium‐modulated EMAC. 相似文献
994.
Selectfluor and NFSI exo‐Glycal Fluorination Strategies Applied to the Enhancement of the Binding Affinity of Galactofuranosyltransferase GlfT2 Inhibitors
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Dr. Lidia Dumitrescu Dr. Guillaume Eppe Abdellatif Tikad Dr. Weidong Pan Sandy El Bkassiny Sudagar S. Gurcha Dr. Ana Ardá Prof. Jesús Jiménez‐Barbero Prof. Gurdyal S. Besra Prof. Stéphane P. Vincent 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15208-15215
Two complementary methods for the synthesis of fluorinated exo‐glycals have been developed, for which previously no general reaction had been available. First, a Selectfluor‐mediated fluorination was optimized after detailed analysis of all the reaction parameters. A dramatic effect of molecular sieves on the course of the reaction was observed. The reaction was generalized with a set of biologically relevant furanosides and pyranosides. A second direct approach involving carbanionic chemistry and the use of N‐fluorobenzenesulfonimide (NFSI) was performed and this method gave better diastereoselectivities. Assignment of the Z/E configuration of all the fluorinated exo‐glycals was achieved based on the results of HOESY experiments. Furthermore, fluorinated exo‐glycal analogues of UDP‐galactofuranose were prepared and assayed against GlfT2, which is a key enzyme involved in the cell‐wall biosynthesis of major pathogens. The fluorinated exo‐glycals proved to be potent inhibitors as compared with a series of C‐glycosidic analogues of UDP‐Galf, thus demonstrating the double beneficial effect of the exocyclic enol ether functionality and the fluorine atom. 相似文献
995.
Nanoarchitectured Graphene‐Based Supercapacitors for Next‐Generation Energy‐Storage Applications
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Rahul R. Salunkhe Ying‐Hui Lee Kuo‐Hsin Chang Jing‐Mei Li Patrice Simon Jing Tang Nagy L. Torad Prof. Dr. Chi‐Chang Hu Prof. Dr. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):13838-13852
Tremendous development in the field of portable electronics and hybrid electric vehicles has led to urgent and increasing demand in the field of high‐energy storage devices. In recent years, many research efforts have been made for the development of more efficient energy‐storage devices such as supercapacitors, batteries, and fuel cells. In particular, supercapacitors have great potential to meet the demands of both high energy density and power density in many advanced technologies. For the last half decade, graphene has attracted intense research interest for electrical double‐layer capacitor (EDLC) applications. The unique electronic, thermal, mechanical, and chemical characteristics of graphene, along with the intrinsic benefits of a carbon material, make it a promising candidate for supercapacitor applications. This Review focuses on recent research developments in graphene‐based supercapacitors, including doped graphene, activated graphene, graphene/metal oxide composites, graphene/polymer composites, and graphene‐based asymmetric supercapacitors. The challenges and prospects of graphene‐based supercapacitors are also discussed. 相似文献
996.
In this study, novel bio-based hydroxyl-end-capped (co)polyesters from dimethyl-2,5-furandicarboxylate (DMF), 2,3-butanediol, and a variety of comonomers viz. glycerol, pentaerythritol or trimethylolpropane are prepared using a solvent-free, bulk polycondensation technique. Extensive molecular and thermal characterization was performed to elucidate the properties of these materials. The materials showed suitable properties for solvent-borne coating applications in terms of their molecular weight, functionality and thermal characteristics, and coatings were prepared using the isocyanurate of hexamethylene diisocyanate as a cross-linker. The resulting coatings, having thicknesses between 30 and 55 μm, were hard but rather brittle. All the coatings have good solvent resistance, pointing to sufficient network formation. It is clear that the presented DMF-based polyesters show promise as bio-based coating resins. 相似文献
997.
Cu2ZnSnSe4 (CZTSe) films for solar cell devices were fabricated by sputtering of a Cu-Zn-Sn target followed by post-selenization at 500–600 °C for 1 h in the presence of single or double compensation discs to supply Se vapor. The optimized selenization conditions avoided the Se deficiency and enhanced the grain growth of CZTSe films. The 600 °C-selenized CZTSe films adjacent with double discs obtained the large grains of 2–5 μm and had a [Cu]/([Zn]+[Sn]) ratio of 0.94 and a [Zn]/[Sn] ratio of 1.34. In order to fabricate the device on Mo-coated glass substrates, a TiN reaction barrier layer was coated before the Cu-Zn-Sn sputtering coating. The TiN-CZTSe device had 3.7 % efficiency (η), as compared to 0.58 % for the TiN-free one. The efficient device had the CZTSe layer with hole concentration (n p) of 3.4 × 1017 cm?3, Hall mobility (μ) of 54 cm2 V?1 s?1, and electrical conductivity (σ) of 2.9 Ω?1 cm?1. 相似文献
998.
999.
采用普通的打印纸经过简单工艺制作出纸太赫兹半波片。使用太赫兹时域光谱(THzTDS)技术,测量了纸波片在200 GHz~400 GHz的折射率、吸收系数、频谱、消光比、参数C等光学特性随纸波片取向的变化关系,将实验结果与理论分析相结合,发现该纸波片是对频率为282.5 GHz的半波片。 相似文献
1000.
The generation structure of quarks and leptons is studied in a series of extended electroweak models. They are gauge models constructed from subgroups of left-right symmetric SU(4) × SPL(6) × SPR(6). In particular, SUC(3) × SPL(6) × UY(1), as well as SUC(3) × SUL(3) × SUR(3) × UX(1), are investigated in greater detail. It is shown that models based on such subgroups yield massless first generation fermions at the tree level. They acquire masses from those of the third generation via two-loop radiative corrections. Moreover, since such corrections are induced by charged scalar fields, it is found that there is a natural correlation between the two apparently conflicting inequalities mu < md and mt > mb. 相似文献