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41.
Hemin was physically adsorbed onto porous carbon felt (CF), a microelectrode ensemble of micro-carbon fiber (ca. 7 μm in diameter) and possessing a three-dimensional random structure. The hemin-CF exhibited a well-defined redox wave that is due to Fe(III)/Fe(II) redox process in hemin, with a formal potential of ?0.32 V (vs. Ag/AgCl) in deoxygenated buffer solution of pH 7.0. The surface coverage of the electroactive hemin molecules on the surface of the CF was calculated to be 5.0?×?10?11 mol cm?2, and the apparent heterogeneous electron transfer rate constant is 3.35 s?1. The hemin-CF electrode displays excellent electrocatalytic activity for the reduction of dissolved oxygen (DO), and the magnitude of the cathodic current increases with increasing concentrations of DO in the sample solution. The electrode was used as a flow-through detector for sensitive and rapid consecutive determination of DO. Deoxygenated pH 7.0 solutions were analyzed at a flow rate of 8.0 mL min?1 at an applied potential of ?0.2 V, and highly reproducible cathodic peak current responses to DO were observed in the 0.72 to 13.3 mg L?1 concentration range. The maximum throughput is 170 samples h?1. The hemin-CF-based amperometric flow-sensor was applied to determine the concentration of DO in environmental water samples. Graphical abstract
Hemin was physically adsorbed onto porous carbon felt (CF), a microelectrode ensemble of micro-carbon fiber (ca. 7 μm in diameter). The hemin-CF electrode was used as a flow-through detector for highly sensitive and rapid determination of dissolved oxygen. 相似文献
42.
Nobutaka Yamaoka Kohei Sumida Itsuki Itani Hiroko Kubo Yusuke Ohnishi Sho Sekiguchi Dr. Toshifumi Dohi Prof. Dr. Yasuyuki Kita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):15004-15011
Metal‐free oxidative C? C coupling by using polyalkoxybenzene‐derived diaryliodonium(III) salts as both the oxidant and aryl source has been developed. These salts can induce single‐electron‐transfer (SET) oxidation to yield electron‐rich arenes and subsequently transfer the polyalkoxyphenyl group into in situ generated aromatic radical cations to produce biaryl products. The reaction is promoted by a Lewis acid that activates the iodonium salts. It has been revealed that the reactivity of the salts under acidic conditions is quite different to their known behavior under basic conditions. The reactivity preference of a series of iodonium salts in the SET oxidation and their ligand transfer abilities have been systematically investigated and the results are summarized in this report. 相似文献
43.
Assembly of Na3V2(PO4)3 Nanoparticles Confined in a One‐Dimensional Carbon Sheath for Enhanced Sodium‐Ion Cathode Properties
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Dr. Satoshi Kajiyama Dr. Jun Kikkawa Junichi Hoshino Dr. Masashi Okubo Dr. Eiji Hosono 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(39):12636-12640
Structural and morphological control is an effective approach for improvement of electrochemical properties in rechargeable batteries. One‐dimensionally assembled structure composed of NASICON‐type Na3V2(PO4)3 nanoparticles were fabricated through an electrospinning method to meet the requirements for the development of efficient electrode materials in Na‐ion batteries. High‐temperature treatment of electrospun precursor fibers under an argon flow provides a nonwoven fabric of nanowires comprising crystallographically oriented nanoparticles of NASICON‐type Na3V2(PO4)3 within a carbon sheath. The mesostructure comprising NASICON‐type Na3V2(PO4)3 and carbon give a short sodium‐ion transport pass and an efficient electron conduction pass. Electrochemical properties of NASICON‐type Na3V2(PO4)3 are improved on the basis of one‐dimensional nanostructures designed in the present study. 相似文献
44.
Suzuki T Arai K Goto H Hanano M Watanabe J Tomono K 《Chemical & pharmaceutical bulletin》2002,50(6):741-743
Nifedipine-containing calcium phosphate cement (CPC) was prepared, and nifedipine (NF) release from this preparation was evaluated by the shaking method (SK), Japanese Pharmacopoeia XIV (JPXIV) paddle method (PD), and JPXIV flow-through cell method (FT). The release of NF from the CPC preparation continued for 7 d or longer by all these methods. This suggests that the release of NF can be controlled by preparing NF-containing CPC. The release pattern of NF from CPC in these tests was found to follow the Higuchi equation. However, the Higuchi constant differed among the three dissolution tests, probably because the apparent tortuosity of capillary system (tau) varied. 相似文献
45.
F(2) excimer-laser irradiation induces two major changes in SiO(2): OH glass impregnated with H(2) molecules. First, the vacuum-UV optical absorption edge is bleached, and the absorption at 157 nm decreases from 0.95 to 0.68 cm(-1) . Second, preexisting free SiOH groups and interstitial H(2) are photochemically converted to hydrogen-bonded hydroxyl groups. It is suggested that the bleaching of the UV-absorption edge is caused by a change of OH groups from a free to a hydrogen-bonded state and by photolysis of distorted Si-O bonds that are absorbing in the edge region. 相似文献
46.
47.
The ESR spectra of the 5s1 state of Cd+, induced with gamma-ray irradiation, were measured for polycrystalline CaO, β-Ca(PO3)2 and glassy Ca(PO3)2 matrices. It has been found out that one of the hyperfine absorptions due to the magnetic nuclei (111Cd and 113Cd) reflects very senstively the structural fluctuation around the center in terms of pronounced line broadening. Such a feature was explained reasonably well by introducing the distribution of the hyperfine coupling constant. It was emphasized that Cd2+, the precursor of Cd+, is a very suitable probe to study the local randomness around Ca2+ in solids. 相似文献
48.
Ikeda S Sanuki R Miyachi H Miyashita H Taniguchi M Odashima K 《Journal of the American Chemical Society》2004,126(33):10331-10338
A Ni(0)/ZnCl(2) system effectively promotes the coupling of enones and alkene-tethered alkynes. In the reaction with 1,6-enynes, the oxidative cyclization of Ni(0) species on enones across the alkyne part followed by ZnCl(2)-promoted cleavage generates alkenylnickel intermediates. Subsequent migratory insertion of the tethered alkene occurs with 5-exo-cyclization. When the resulting sigma-alkylnickel intermediates have beta-hydrogen atoms, the reaction terminates by beta-hydrogen elimination to provide cyclopentane derivatives. On the other hand, a sigma-alkylnickel intermediate that does not have beta-hydrogen atoms undergoes the insertion of a second alkene unit to cause a domino effect via a three-fold C-C bond formation process with and without the cleavage of one C-C bond. 相似文献
49.
The nanoporous main group oxide 12CaO.7Al(2)O3 (C12A7) can be transformed from a wide-gap insulator to an electride where electrons substitute anions in cages constituting a positive frame. Our ab initio calculations of the electronic structure of this novel material give a consistent explanation of its high conductivity and optical properties. They show that the electrons confined in the inert positive frame are localized in cages and undergo hopping between neighboring cages. The results are useful for the understanding of behavior of confined electron gas of different topology and electron-phonon coupling, and for designing new transparent conductors, electron emitters, and electrides. 相似文献
50.
Machida K Takehara E Kobayashi H Kikuchi M 《Chemical & pharmaceutical bulletin》2003,51(12):1417-1419
Two new iridoid glycosides, 7 beta,8 beta-epoxy-8 alpha-dihydrogeniposide (1) and 8-epiapodantheroside (2), were isolated, together with six known (3-8) and three artifact (9-11) iridoids, from the leaves of Gardenia jasminoides cv. fortuneana Hara. Their structures were established based on chemical and spectral data. 相似文献