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81.
Enhancement of electronic excitation energy transfer in the colloidal crystals of colloidal silica suspensions doped with fluorescent dyes 总被引:1,自引:0,他引:1
Kiyoshi Shibata Hiroshi Kimura Akira Tsuchida Tsuneo Okubo 《Colloid and polymer science》2006,285(2):127-133
The efficiency of electronic excitation energy transfer from photo-excited rhodamine 110 (Rh110, energy donor) to rhodamine B (RhB, energy acceptor) in an exhaustively deionized colloidal silica suspension has been studied. This colloidal suspension shows Bragg reflection due to the formation of colloidal crystals and the Bragg-peak wavelength is controllable by the volume fraction of the silica spheres. When the Bragg-peak wavelength matches with the fluorescence band of Rh110, a depletion was observed in the Rh110 fluorescence spectrum. This means the fluorescence of Rh110 is partially trapped due to the Bragg reflection inside the crystal lattice. In the coexistence of RhB, the enhancement of RhB fluorescence intensity was observed. These facts clearly indicate the trapped photon energy of Rh110 is efficiently transferred to RhB within the colloidal crystals. The quantitative measurements showed that the enhancement of the transfer efficiency is 20% (or slightly more) in the present experimental conditions. 相似文献
82.
83.
An evaluation of LH- and FSH-RIA BEAD kits based on IRMA was carried out. The results obtained with the methods characterized by the use of monoclonal antibodies, i.e., one is linked to solid phase, and another is isotopically labeled, were compared with those determined by the Daiichi LH- and FSH-kits. Intra- and inter-assay precision, recovery, linearity, and specificity of both methods were favorable without exceptions. The cross reactivity of the LH kit to 5,000 mIU/ml hCG revealed within the range of less than 3 mIU/ml. Significant correlations were observed between the results derived from conventional Daiichi LH- and FSH-kits. The results from the conventional kits exhibited 30 to 40% of those from the Daiichi kits, considered to be mainly due to the difference in standard calibrations used. Among the individuals within the normal menstrual cycle, the serum LH- and FSH-levels determined by the present kits gave a typical pattern with a peak in the preovulatory phase. On the other hand, the LH- and FSH-values of individuals in normal pregnancy revealed strikingly decreased in comparison with those of non-pregnant women. 相似文献
84.
Kinetics of chemiluminescence reactions of 2-methyl-6-phenylimidazo[1,2-a]pyrazin-3(7H)-one (1c, Cypridina luciferin analogue) and substituent effects of the 6-aryl group of derivatives 1 strongly suggest that the rate-determining step is a single electron transfer from an anion derived from 1 to a triplet molecular oxygen (O2) in the oxygenation process. 相似文献
85.
K Sakai Y Miyazaki T Yamane Y Saitoh C Ikawa T Nishihata 《Chemical & pharmaceutical bulletin》1989,37(1):215-217
Some of the Zingiberaceae herbs are known to be useful as stomachics. Water extracts and methanol extracts of eight such herbs were examined in intact unanesthetized rabbits for their effect on gastric secretion. Oral administration of either water extracts or methanol extracts caused a significant decrease in gastric secretion. A significant effect of these extracts appeared at 3 h after administration. The effect of water extracts on gastric secretion was very similar to that of cimetidine, with a significant decrease in acid output. The effect of the methanol extracts was primarily observed as decreased pepsin output. 相似文献
86.
87.
The solubility of glycine,
-alanine,
-valine,
-leucine, and
-isoleucine in water was measured at 298.15 K and pressures up to 400 MPa. The standard deviation of the logarithm of the solubility is 0.001–0.003, equal to or better than the accuracy of atmospheric pressure measurement in the literature (0.001–0.05). A variety of solubility phenomena were observed. The solubility of glycine decreased with increasing pressure, whereas that of
-alanine increased. The
-valine and
-isoleucine have a solubility maximum at around 100 MPa, and
-leucine seems to exhibit a solid-phase phase transition at around 200 MPa. Pressure coefficient of the solubilities at 0.10 MPa is compared with that thermodynamically estimated in reference to aqueous density measurements of glycine and
-alanine at 298.15 K and 0.10 MPa, supporting a reliability of our high-pressure measurements. 相似文献
88.
89.
Yoshihiko Nishimori Katsuhiko Kanaizuka Dr. Masaki Murata Dr. Hiroshi Nishihara Prof. 《化学:亚洲杂志》2007,2(3):367-376
Films of linear and branched oligomer wires of Fe(tpy)2 (tpy=2,2′:6′,2′′‐terpyridine) were constructed on a gold‐electrode surface by the interfacial stepwise coordination method, in which a surface‐anchoring ligand, (tpy? C6H4N?NC6H4? S)2 ( 1 ), two bridging ligands, 1,4‐(tpy)2C6H4 ( 3 ) and 1,3,5‐(C?C? tpy)3C6H3 ( 4 ), and metal ions were used. The quantitative complexation of the ligands and FeII ions was monitored by electrochemical measurements in up to eight complexation cycles for linear oligomers of 3 and in up to four cycles for branched oligomers of 4 . STM observation of branched oligomers at low surface coverage showed an even distribution of nanodots of uniform size and shape, which suggests the quantitative formation of dendritic structures. The electron‐transport mechanism and kinetics for the redox reaction of the films of linear and branched oligomer wires were analyzed by potential‐step chronoamperometry (PSCA). The unique current‐versus‐time behavior observed under all conditions indicates that electron conduction occurs not by diffusional motion but by successive electron hopping between neighboring redox sites within a molecular wire. Redox conduction in a single molecular wire in a redox‐polymer film has not been reported previously. The analysis provided the rate constant for electron transfer between the electrode and the nearest redox‐complex moiety, k1 (s?1), as well as that for intrawire electron transfer between neighboring redox‐complex moieties, k2 (cm2 mol?1 s?1). The strong effect of the electrolyte concentration on both k1 and k2 indicates that the counterion motion limits the electron‐hopping rate at lower electrolyte concentrations. Analysis of the dependence of k1 and k2 on the potential gave intrinsic kinetic parameters without overpotential effects: k10=110 s?1, k20=2.6×1012 cm2 mol?1 s?1 for [n Fe 3 ], and k10=100 s?1, k20=4.1×1011 cm2 mol?1 s?1 for [n Fe 4 ] (n=number of complexation cycles). 相似文献
90.
Hiroshi Harada Kanichi Kamiya Hiroyuki Nasu Jun Matsuoka 《Journal of Sol-Gel Science and Technology》1997,10(3):291-300
The sodium dititanate, Na2O·2TiO2 glass was prepared by the sol-gel method. The structure of the glass, especially local environment of Ti4+ ions was examined using X-ray diffraction and X-ray absorption fine structure (XAFS) analyses, and was compared with that of the melt-derived glass with the same composition. It was found that Ti4+ ions are rather in five-fold coordination state, forming TiO5 pyramids with one doubly bonded Ti=O in the gel-glass, while they were in lower coordination state or four-fold coordination in the melt-derived glass. 相似文献