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31.
32.
Liu J Itoh J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(2):455-459
A kinetic method performed on a flow injection system is described for the determination of ascorbic acid by using its catalytic effect on the complexation reaction of Cu(II) with 5,10,15,20-tetrakis(4-N-trimethyl-aminophenyl)porphyrin. The characteristic spectrum of porphyrin (Soret band), which shows intense absorption around 400 nm (epsilon>2.0 x 10(5) cm(-1)M(-1)), was used first time for determining ascorbic acid. By incorporating the complexation reaction into a flow injection system, ascorbic acid could be determined either over a broad dynamic range of 0.1-1000 microg/ml or at a trace level below 5 ng/ml. Good repeatability was also achieved by testing a working standard of 0.1 microg/ml with 10 injections at a throughput of 35 h(-1), obtaining a relative standard deviation of 0.11%. Substances like amino acids, vitamins, sugars, organic acids and metal ions, showed no or little interference even present at high concentrations. The method was validated in the determination of ascorbic acid contents of some commercially available soft drinks by comparison with the official 2,6-dichloroindophenol method with reasonable agreement. 相似文献
33.
Saito S Shimidzu J Yoshimoto K Maeda M Aoyama M 《Journal of chromatography. A》2007,1140(1-2):230-235
A highly sensitive and selective capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF) for Al(3+) and Ga(3+) was developed using a calcein 4',5'-isomer as a pre-capillary complexing agent. Direct fluorescent detection without an agent added to the carrier buffer provided the notable detection limits of 3.9x10(-10) and 4.6x10(-10)moldm(-3) for Al and Ga, respectively. By applying this system successfully to a river water sample, its potential for practical applications was ascertained. A comparison of three aromatic polyaminocarboxylate ligands related to the coordination structure and the distance between the fluorophore and the chelating moiety, revealed some interesting factors regarding their selectivity. 相似文献
34.
Shingo Sato Hironobu Kumagai Shigeru Matsuba Toshihiro Kumazawa Jun-Ichi Onodera Masanobu Suzuki 《Journal of heterocyclic chemistry》1999,36(5):1345-1347
A flavanone, in which a hydroxyl group at the 5-position was protected with a methyl group, converted to the corresponding 5-methoxy-2-phenyl-4-quinolone via flavylium salt under mild conditions. Flavanone-O-rhamnoglucoside, naringin, was also converted to 5-methoxy-2-phenyl-4-quinolon-7-O-rhamnoglucoside in the same way in an overall 25% yield. 相似文献
35.
The effect of stoichiometry on various features of III-V compounds are investigated. It is shown experimentally that the optimum vapor pressure of V elements minimizes the deviation from the stoichiometric composition. Vapor pressure control technology is applied not only to the liquid phase epitaxy and bulk crystal growth but also to the surface reaction in molecular layer epitaxy. The surface reaction and kinetic phenomena of GaAs mono-molecular layer growth by using chemical adsorption of Ga(CH3)3 (trimethyl gallium: TMG) and arsine (AsH3) was investigated. The growth feature was strongly influenced by the surface stoichiometry of arsenic during growth. For example, the diffusion of the doped impurity is affected by the AsH3 amount of supply, the diffusion was prevented by controlling the stoichiometry. The control of stoichiometry was examined systematically and was applied for the device fabrication such as ballistic transistor. 相似文献
36.
Jun-Ichi Aihara Sumio Oe Mitsuho Yoshida Eiji Ōsawa 《Journal of computational chemistry》1996,17(12):1387-1394
Thermodynamic and kinetic stabilities of 73 C84 fullerene isomers were estimated from the MM3 heats of formation and the recently defined bond resonance energies (BREs), respectively. The BRE represents the contribution of a given π bond in a molecule to the topological resonance energy (TRE). All π bonds shared by two pentagons turned out to be highly reactive without exceptions. C84 fullerene isomers with such π bonds must be incapable of survival during harsh synthetic processes. Thus, the isolated pentagon rule (IPR) proved to be applicable to such large fullerene cages. For sufficiently large fullerenes like C84, some isolated-pentagon isomers are also predicted to be very unstable with highly antiaromatic π bonds. © 1996 by John Wiley & Sons, Inc. 相似文献
37.
M Tada S Zhang S Malwadkar N Ishiguro J Soga Y Nagai K Tezuka H Imoto S Otsuka-Yao-Matsuo S Ohkoshi Y Iwasawa 《Angewandte Chemie (International ed. in English)》2012,51(37):9361-9365
Breaking news: A unique discontinuous property and an active phase of Ni/ordered Ce(2) Zr(2) O(x) (x=7-8) solid-solution catalysts were observed during methane steam reforming. The catalytic performance of Ni/Ce(2) Zr(2) O(x) strongly depended on the phase and oxygen content of the Ce(2) Zr(2) O(x) support. 相似文献
38.
Kim Seok-Jun Sakai Takaaki Oda Hiroyuki Okuyama Yuji Mizutani Yumi Hamagami Jun-Ichi Matsuka Maki Ishihara Tatsumi Matsumoto Hiroshige 《Journal of Solid State Electrochemistry》2012,16(11):3587-3592
Journal of Solid State Electrochemistry - The long-term stability in water was investigated for an inorganic proton conductor based on sulfated hydrous titania electrolyte in water electrolysis.... 相似文献
39.
To investigate the π bonding electron contribution to N-HO[double bond, length as m-dash]C hydrogen-bond (H-bond) formation, we applied IR cavity ringdown spectroscopy to jet-cooled pyrrole-acetone (Py-Ac) binary clusters. The observed NH stretching vibrations were analyzed by density functional theory (DFT), in which the energetically optimized structures, harmonic frequencies, and interaction energies were calculated for various sizes of binary clusters. We observed three NH stretching vibrations, ascribed to binary clusters at 3406, 3388, and 3335 cm(-1). These were assigned to H-bonded NH stretches of the Py(2)-Ac(1), Py(1)-Ac(1), and Py(1)-Ac(2) clusters, respectively. The Py(1)-Ac(1) cluster has a single N-HO[double bond, length as m-dash]C H-bonded structure with C(s) symmetry, while the Py(1)-Ac(2) cluster has a cyclic structure formed by a single N-HO[double bond, length as m-dash]C H-bond, dipole-dipole interactions, and weak CH H-bonds. A natural bond orbital (NBO) analysis was performed to reveal the H-bond strength in Py-Ac binary clusters. For the Py(1)-Ac(2) cluster, we found that the donor-acceptor interactions are not only the n →σ* type (O atom lone pair to the NH anti-bonding orbitals), but also the π→σ* type (the CO π bonding to the NH anti-bonding orbitals). By analyzing the relationship between the frequency shift and the stabilization energy in donor-acceptor interactions, we concluded that larger red-shift of the NH stretching vibration in the Py(1)-Ac(2) can be explained by not only the lone pair and the π electron contributions to the N-HO[double bond, length as m-dash]C H-bond, but also the dipole-interaction between Py and non-H-bonded Ac. We also discussed the structures of Py(2)-Ac(1) clusters. 相似文献
40.
Masami Kurano Masami Yasuda Jun-Ichi Nakagami Yuji Yoshida 《Fuzzy Optimization and Decision Making》2004,3(4):367-374
Stimulated by Zadeh's paper (Journal of Statistical Planning and Inference,2002, 105, 233--264), we will try to consider a perceptive analysis of the optimal stopping problem. In this paper, the fuzzy perception value of the expectation of the optimal stopped reward is characterized and calculated by a new recursive equation. Also, a numerical example described by triangular fuzzy numbers is given. 相似文献