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221.
Sasakura H Kuramitsu S Hayashi Y Tanaka K Akazaki T Hanamura E Inoue R Takayanagi H Asano Y Hermannstädter C Kumano H Suemune I 《Physical review letters》2011,107(15):157403
We experimentally demonstrate Cooper pairs' drastic enhancement of the band-to-band radiative recombination rate in a semiconductor. Electron Cooper pairs injected from a superconducting electrode into an active layer by the proximity effect recombine with holes injected from a p-type electrode. The recombination of a Cooper pair with p-type carriers dramatically increases the photon generation probability of a light-emitting diode in the optical-fiber communication band. The measured radiative decay time rapidly decreases with decreasing temperature below the superconducting transition temperature of the niobium electrodes. Our results indicate the possibility to open up new interdisciplinary fields between superconductivity and optoelectronics. 相似文献
222.
M. Hagiwara A. Fujii T. Hayashi T. Shima H. Deguchi 《Physica C: Superconductivity and its Applications》2011,471(21-22):693-697
Faint electric resistivity behavior is searched experimentally near and below intergrain ordering temperature of weakly sintered ceramic YBa2Cu4O8 (Y124). For this purpose, a new method to detect linear and nonlinear resistivity sensitively by combination of pulse delta method and numerical Fourier-transformation has been designed. Making use of the experimental system for several weak sintered Y124 samples, it is revealed that linear resistivity just above the intergrain ordering point first drops toward zero steeply with decreasing temperature, and then turns abruptly upward to forms faint maximum at lower temperature. Such a novel behavior of ‘revival of resistivity’ is confirmed to be reproducible, and considered to be an essential frustration effect for d-wave type grain system with irregular or inhomogeneous ceramic structure. 相似文献
223.
Hirokazu KitauraAkitoshi Hayashi Kiyoharu TadanagaMasahiro Tatsumisago 《Solid State Ionics》2011,192(1):304-307
To improve the electrochemical performance of an all-solid-state In/80Li2S⋅20P2S5 (electrolyte)/LiMn2O4 cell, a lithium-titanate thin film was used to coat LiMn2O4. The interfacial resistance between LiMn2O4 and the electrolyte (measured after initial charging) decreased when the LiMn2O4 particles were coated with lithium-titanate. A cell with lithium-titanate-coated LiMn2O4 had a higher capacity than a cell with noncoated LiMn2O4 for current densities in the range 0.064 to 2.6 mA cm− 2. Additionally, a cell with coated LiMn2O4 retained 96% of the 10th-cycle reversible capacity at a current density of 0.064 mA cm− 2 after 50 cycles. 相似文献
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Shin-ichiro Hayashi Munenori Yoshioka Shuji Usui Kiyofumi Haneda Takahiro Kondo Kim B. McAuley Takahiro Tominaga 《Radiation Physics and Chemistry》2010,79(7):803-808
In radiotherapy treatment, polymer gel dosimetry can be used for verifying three-dimensional (3D) dose distributions. Gelatin is generally used as a gelling agent in the dosimeters. In this paper, another role of gelatin in a methacrylic-acid-based gel dosimeter (MAGAT) is investigated. Temperature increases due to exothermic polymerization in the irradiated gel are measured directly. Dose–R2 responses are also obtained using MRI. It is shown that no appreciable increases in either temperature or R2 are observed in MAGAT dosimeters made without gelatin, and that significant temperature and R2 increases are observed when very low gelatin concentrations are used. These results indicate that gelatin is an important enabler for radiation-induced free-radical polymerization in methacrylic-acid-based gels. When gelatin is replaced by amino acids, changes in temperature are observed, along with small changes in R2. The resulting dosimeter solutions remain transparent because the polymer does not precipitate as it does in regular MAGAT dosimeters containing gelatin. When the amino acids are replaced by acids without amino groups, no temperature or R2 changes are observed, indicating that no polymer forms. These results show that amino groups (and possibly other functional groups) on the gelatin catalyze the radiation-induced free-radical polymerization that occurs in MAGAT dosimeters. 相似文献
229.
H. Roy-Poulsen E. Johnson A. Johansen L. Sarholt-Kristensen H. Hayashi 《Hyperfine Interactions》1986,29(1-4):1201-1204
Martensitic transformations have been analysed in a series of antimony implanted austenitic stainless steels using CEMS. The
implanted samples contain about 70 vols martensite, which is considerably more than can be formed conventionally by plastic
deformation or cooling below the martensite start temperature. CEM spectra from implantation induced martensite and from martensite
formed in conventional processes are virtually identical. In both cases the hyperfine field is ≈ 25T. 相似文献
230.
Ryoji Kurita Katsuyoshi Hayashi Keiichi Torimitsu Osamu Niwa 《Analytical sciences》2003,19(12):1581-1585
We first measured the effects of trace levels of an endocrine disruptor, tributyltin (TBT), on the secretion response from nerve cells using a microfabricated biosensor designed for the continuous measurement of L-glutamate and hydrogen peroxide. We observed higher and long-lasting glutamate and hydrogen peroxide concentrations from the cells when cultured rat cortical neurons were exposed to TBT. Glutamate and hydrogen peroxide release was induced even when we reduced the TBT concentration to 10 nM. This concentration is about two orders of magnitude lower than the concentration that induced apoptosis-like cell death. We also report on the effects of NMDA and non-NMDA receptor antagonists, which can help us to understand the mechanism of TBT neurotoxicity. 相似文献