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61.
Yellow-emitting Vibrio fischeri Y1 modulates its bioluminescence (BL) depending on the dissolved O2 concentration. On supplying O2 to the cells under anaerobiosis, the cells begin to emit striking yellow BL peaking around 535 nm. The enhanced yellow emission reverts reversibly to the original level after O2 is consumed. Moreover, the reversible rise and fall of the yellow emission occurs repeatedly in accord with the repeating cycles of aeration on and off. This indicates that an increase in the cellular amount of yellow fluorescent protein (YFP) is not an immediate cause of the yellow emission enhancement. One suggested explanation is that the activity of YFP originating from its highly fluorescent property is altered by redox interaction with the respiratory components, including the soluble cytochrome c. Under the O2-limited conditions, the cellular YFP molecules, in part, seem to lose the fluorescent property possibly because of being reduced via redox interaction with some respiratory components in reduced form. On stimulating aerobic respiration with O2 supply, the reduced YFP seems to retrieve its fluorescent property via oxidation possibly with both O2, diffused across the cell membrane, and ferricytochrome c, generated during the respiratory turnover. The suggested redox interactions seem primarily to cause the reversible BL modulation. 相似文献
62.
Toshikazu Kaise Hiroshi Yamauchi Yoshiya Horiguchi Takayuki Tani Shigenobu Watanabe Teruhisa Hirayama Shozo Fukui 《应用有机金属化学》1989,3(3):273-277
The acute toxicity of methylarsonic acid, CH3AsO(OH)2 (MAA), dimethylarsininc acid, (CH3)2AsO(OH) (DMAA), and trimethylarsine oxide, (CH3)3AsO (TMAO), were examined in mice with oral administration. The LD50 values of MAA, DMAA and TMAO were 1.8, 1.2 and 10.6 g kg?1 respectively. The toxicity of MAA and DMAA was very much lower than that for inorganic arsenic compounds. It was shown that TMAO has a similar acute toxicity to arsenobetaine. On the other hand, when the mice were administered 14.4 g kg?1 of TMAO once only orally, a garlic-like odor (trimethylarsine, (CH3)3As) was definitely detectable in the exhalation of the animals by the human olfactory sense within about a few minutes. 相似文献
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66.
G. Dujardin L. Philippe M. Rose T. Hirayama M.J. Ramage G. Comtet L. Hellner 《Applied Physics A: Materials Science & Processing》1998,66(5):527-538
Received: 16 June 1997/Accepted: 26 October 1997 相似文献
67.
A significant temperature effect on the new photochemical reactions of 9-α-bromopropionylanthracene has been noted. In comparison to the temperature effect on the fluorescence intensity of 9-propionylanthracene, it was suggested that the rotation of the carbonyl group on photo-excitation might operate as an enhancing factor in the intersystem crossing process. 相似文献
68.
We studied on the radio‐frequency molecular beam epitaxial (RF‐MBE) growth of GaN/AlGaN quantum cascade (QC) structure grown on a metal organic chemical vapor deposition (MOCVD)‐GaN template by employing the droplet elimination by thermal annealing (DETA) technique, in order to realize the successful fabrication of a QC structure with a large number of periods and to increase the radiant intensity from terahertz‐quantum cascade lasers (THz‐QCL) sample. DETA is a technique in which the metal droplets that form on the surface are evaporated and eliminated by temporarily increasing the substrate temperature, utilizing the property whereby the equilibrium vapor pressures of the metal components (Ga, Al) are larger than those of the resulting nitrides (GaN, AlN). DETA is a useful method which not only makes it possible to increase the number of periods in the QC structure, but also to improve the surface and structural properties of the QC structure. We could successfully increase the radiant intensity from a THz‐QCL sample by increasing the number of periods in the stacked QC structure by using the DETA technique. 相似文献
69.
S. Anceau P. Lefebvre T. Suski L. Konczewicz H. Hirayama Y. Aoyagi 《physica status solidi (a)》2005,202(4):642-646
The competition between radiative and nonradiative recombination of electron‐hole pairs in (Al,In,Ga)N/(Al,In,Ga)N quantum wells of two different compositions and various well widths was investigated in order to understand the microscopic mechanisms of the highly intense light emission from this type of structures. By using time‐resolved photoluminescence, we have verified that one can adjust the compositions of the quaternaries so as to optimize the confinement effects and to minimize the built‐in electric field which is present in such hexagonal group‐III nitride based QWs. The role of local potential fluctuations in the quaternary alloy on the localization of carriers was studied and analyzed by measuring the photoluminescence energy, intensity and dynamics versus temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
70.
We investigate nonequilibrium transport in the absence of spin-flip energy relaxation in a few-electron quantum dot artificial atom. Novel nonequilibrium tunneling processes involving high-spin states, which cannot be excited from the ground state because of spin blockade, and other processes involving more than two charge states are observed. These processes cannot be explained by orthodox Coulomb blockade theory. The absence of effective spin relaxation induces considerable fluctuation of the spin, charge, and total energy of the quantum dot. Although these features are revealed clearly by pulse excitation measurements, they are also observed in conventional dc current characteristics of quantum dots. 相似文献