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Renormalized bosonic interaction of excitons

Physical Review B 2000年第4期61卷 2863-2863页

作者： Jun-ichi Inoue Tobias Brandes Akira Shimizu Core Research for Evolutional Science and Technology JST Honcho 4-1-8 Japan Department of Basic Science University of Tokyo Komaba 3-8-1 Japan

An effective bosonic Hamiltonian of 1s excitons with “spin” degrees of freedom in two dimensions is obtained through a projection procedure, starting from a conventional electron-hole Hamiltonian Heh. We first demonstrate that a straightforward transformation of Heh into a Hamiltonian of bosonic excitons does not give the two-body interaction between an “up-spin” exciton and a “down-spin” exciton, which are created by the left- and right-circularly polarized light beams, respectively. We then show that this interaction is generated through a projection procedure onto the subspace spanned by 1s excitons, as a renormalization effect coming from higher exciton states. The projection also renormalizes the interaction between 1s excitons with the same spins by a large amount. These renormalization effects are crucial for the polarization dependence of the optical responses from semiconductors. The present theory gives the microscopic foundation of the phenomenology that was successfully applied to the analysis of four-wave mixing experiments in GaAs quantum wells strongly coupled to the radiation field in a high-Q microcavity.

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BH4 domain of antiapoptotic Bcl-2 family members closes voltage-dependent anion channel and inhibits apoptotic mitochondrial changes and cell death (vol 97, pg 3100, 2000)

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PROCEEDINGS OF THE NATIONAL ACADEMY OF scienceS OF THE UNITED STATES OF AMERICA 2000年第16期97卷 9347-9347页

作者： Shimizu, S Konishi, A Kodama, T Tsujimoto, Y Osaka University Graduate School of Medicine Biomedical Research Center Department of Medical Genetics and Core Research for Evolutional Science and Technology (CREST) of Japan Science and Technology Corporation 2-2 Yamadaoka Suita.

A change of mitochondrial membrane permeability is essential for apoptosis, leading to translocation of apoptogenic cytochrome c and apoptosis-inducing factor into the cytoplasm. We recently showed that the Bcl-2 family of proteins regulate cytochrome c release and the mitochondrial membrane potential (Deltapsi) by directly modulating the activity of the voltage-dependent anion channel (VDAC) through binding. Here we investigated the biochemical role of the conserved N-terminal homology domain (BH4) of Bcl-x(L), which has been shown to be essential for inhibition of apoptosis, with respect to the regulation of mitochondrial membrane permeability and found that BH4 was required for Bcl-x(L) to prevent cytochrome c release and Deltapsi loss. A study using VDAC liposomes revealed that Bcl-x(L), but not Bcl-x(L) lacking the BH4 domain, inhibited VDAC activity. Furthermore, BH4 oligopeptides of Bcl-2 and Bcl-x(L), but not mutant peptides, were able to inhibit both VDAC activity on liposomes even in the presence of Bax and apoptotic Deltapsi loss in isolated mitochondria. It was also shown that the BH4 domain, fused to the protein transduction domain of HIV TAT protein (TAT-BH4), efficiently prevented apoptotic cell death. These results indicate that the BH4 of Bcl-2/Bcl-x(L) is essential and sufficient for inhibiting VDAC activity, which in turn prevents apoptotic mitochondrial changes, and for preventing apoptotic cell death. Finally, the data suggest that the TAT-BH4 peptide is potentially useful as a therapeutic agent for diseases caused by accelerated apoptosis.

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Transient nondegenerate four-wave mixing signal induced by exciton-exciton interactions in a self-organized quantum-well material

Transient nondegenerate four-wave mixing signal induced by e...

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Nonlinear Optics: Materials, Fundamentals and Applications

作者： J. Ishi Y. Kato H. Kunugita K. Ema T. Ban T. Kondo Department of Physics Sophia University Chiyoda Tokyo Japan Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Japan Department of Material Science University of Tokyo Bunkyo Tokyo Japan

ISBN: (纸本)1557526451

Polarization-dependent nondegenerate four-wave-mixing signal on a self-organized quantum-well material is measured and analyzed with seven-level density matrix description accounting for phase-space filling, excitation-induced dephasing and biexciton formation effects. It reveals these exciton-exciton interactions significantly influence polarization dependence.

关键词： Four-wave mixing Optical films Nonlinear optics Optical mixing Optical network units Optical filters Materials science and technology Optical polarization Excitons Optical pulses

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Self-Consistent Density Functional Calculation of Field Emission Currents from Metals

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Physical Review Letters 2000年第8期85卷 1750-1750页

作者： Y. Gohda Y. Nakamura K. Watanabe S. Watanabe Department of Materials Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation Japan Department of Physics Science University of Tokyo 1-3 Kagurazaka Shinjuku-ku Tokyo 162-8601 Japan

We have developed a fully self-consistent method which is suitable to examine field emission currents, on the basis of the density functional theory. In our method, the nearby counterelectrode is not necessary. By using this method, we have investigated field emission currents from a biased metallic surface represented by the jellium model. We have found that the energy barrier between the jellium and vacuum becomes lower than the Fermi energy under strong electric fields (e.g., 10 V/nm for rs=4 bohr). In this situation, the slope of the Fowler-Nordheim plot becomes flatter than that under a weaker field.

关键词： Field emission cathodes

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Synchrotron x-ray-diffraction study of orbital ordering in YVO3

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Physical Review B 2000年第14期62卷 R9271(R)-R9271(R)页

作者： M. Noguchi A. Nakazawa S. Oka T. Arima Y. Wakabayashi H. Nakao Y. Murakami Institute of Materials Science University of Tsukuba Tsukuba 305-8573 Japan Photon Factory Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukuba 305-0801 Japan Core Research for Evolutional Science and Technology (CREST) Tsukuba 305-0047 Japan

Synchrotron x-ray-diffraction experiments have been carried out in a perovskite-type vanadium oxide YVO3 to elucidate orbital ordering of the system. The change from C- to G-type orbital ordering at the lower magnetic transition temperature was strongly suggested. The long-range orbital ordering appears also in the high-temperature paramagnetic phase. Azimuthal-angle dependence of orbital superlattice reflections indicates that for both orbital-ordering phases the orbital occupation is approximately the dxy1dyz1 and dxy1dzx1 configuration in two sublattices, respectively. These results are in good agreement with a theoretical prediction.

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Generation of coherent phonon oscillations in PbI/sub 2/ thin films

Generation of coherent phonon oscillations in PbI/sub 2/ thi...

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Nonlinear Optics: Materials, Fundamentals and Applications

作者： Y. Hirobe N. Ogawa H. Kunigita K. Ema T. Ban T. Kondo Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Japan Department of Physics Sophia University Chiyoda Tokyo Japan Jochi Daigaku Chiyoda-ku Tokyo JP Department of Mureriul Science University of Tokyo Bunkyo Tokyo Japan

We performed pump-probe transient absorption measurements around the exciton resonance in PbI/sub 2/ thin films. Coherent phonon oscillations corresponding to A/sub 1/ lattice mode were clearly observed at the excitat... 详细信息

关键词： Phonons Transistors Optical films Ultrafast optics Resonance Optical pulses Excitons Optical pumping Optical materials Semiconductor materials

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Precise time-resolved mid-infrared radiometry of shocked CCl4

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AIP Conference Proceedings 2000年第1期505卷 959-962页

作者： Oleg V. Fat’yanov Toshiyuki Ogura Malcolm F. Nicol Ken-ichi Kondo 1Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation 4-1-3 Hon-machi Kawaguchi Saitama 332-0012 Japan 2Materials and Structures Laboratory Tokyo Institute of Technology 4259 Nagatsuta Midori Yokohama 226-8503 Japan 3High Pressure Science and Engineering Center Departments of Chemistry and Physics University of Nevada Las Vegas Las Vegas Nevada 89154-4002

We present the first accurate time-resolved infrared (IR) radiance measurements in two slightly overlapping bands, approximately 7 to 9.5 μm and 9 to 12 μm, for a shock compressed partially transparent inert liquid, CCl4. The main features of the two-channel radiometer were fast liquid N2 cooled, reverse-biased HgCdTe photovoltaic detectors with cut-off frequencies of 100 MHz at 3 dB. Careful analysis of radiance histories based on detailed spectral information allowed us to derive values of the temperature, average absorption coefficients for the shocked material, and reflectivity of the shock front. Shock pressures varied from 3.3 to 9.4 GPa, and the corresponding temperatures ranged from 680 to 1370 K with an uncertainty of 2.5–3% except the lowest temperature which was accurate to ±4.5%. Our equilibrium vibrational temperatures are very consistent with results other groups obtained by pyrometry in the visible and near-infrared. The dependence of the temperature and linear absorption coefficients on pressure clearly indicate the chemical decomposition threshold at 7 GPa reported earlier by other research groups from the data on electrical conductivity and visible light absorption measurements.

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Equation of state for CCl4

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AIP Conference Proceedings 2000年第1期505卷 117-120页

作者： Oleg V. Fat’yanov Malcolm F. Nicol Toshiyuki Ogura Ken-ichi Kondo 1Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation 4-1-3 Hon-machi Kawaguchi Saitama 332-0012 Japan 2Materials and Structures Laboratory Tokyo Institute of Technology 4259 Nagatsuta Midori Yokohama 226-8503 Japan 3High Pressure Science and Engineering Center Departments of Chemistry and Physics University of Nevada Las Vegas Las Vegas Nevada 89154-4002

Thorough analysis of the Us vs. Up principal Hugoniot data for liquid CCl4 shows that our values along with all the data reported by other groups except the low pressure results of Dick can be described by the single smooth function proposed by Woolfolk et al. with the following coefficients: Us/C0=(2.08±0.07)+(1.34±0.04)Up/C0−(1.08±0.07)exp((−1.2±0.2)Up/C0). This satisfies the boundary condition Us=C0=926 m/s at Up=0 and gives the same asymptotic linear relationship as the best-fit expression reported by Dick at shock pressures above ∼16 GPa. On-Hugoniot temperatures calculated using the EOS of Cowperthwaite and Shaw and the revised Us vs. Up are in good agreement with the results of our infrared (IR) measurements and reported optical pyrometry data. The maximum discrepancy does not exceed 5% in the 3.3 to 7 GPa and 10 to 15 GPa shock pressure ranges and is less than 10% for other pressures below 20 GPa. Within the accuracy of our data, the behavior of single-shocked CCl4 does not contradict to the predictions of the constant (∂P/∂T)v model, at least between 3.3 and 7 GPa. All reliable experimental results suggest only two singularities along the principal Hugoniot of CCl4: the threshold of chemical reactions at 7 GPa and complete decomposition at 20 GPa.

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Synthesis and properties of poly(1-naphthylacetylene) and poly(9-anthrylacetylene)

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Journal of Polymer science 2000年第3期37卷

作者： Kazunari Nanjo S. M. Abdul Karim Ryoji Nomura Tatsuo Wada Hiroyuki Sasabe Toshio Masuda Department of Polymer Chemistry Kyoto University Kyoto 606-8501 Japan Core Research for Evolutional Science and Technology (CREST) JST and Frontier Research Program The Institute of Physical and Chemical Research (RIKEN) 2-1 Hirosawa Wako Saitama 351-0198 Japan

Polymerizations of 1-naphthylacetylene (1-NA) and 9-anthrylacetylene (9-AA) by various transition metal catalysts were studied, and properties of the polymers were clarified. 1-NA polymerized with WCl 6 -based catalysts to offer dark purple polymers in good yield. Especially, a binary catalyst composed of WCl 6 and Ph 3 Bi gave a polymer with high molecular weight ( M w = 140×10 3 ) and sufficient solubility in common solvents. The use of Mo and Rh catalysts, in contrast, resulted in the formation of insoluble red poly(1-NA)s. 9-AA gave insoluble polymers by both WCl 6 - and MoCl 5 -based catalysts in moderate to good yields. Copolymerization of 9-AA with 1-NA by WCl 6 –Ph 3 Bi provided a soluble copolymer which exhibited the largest third-order nonlinear optical susceptibilities (χ (3) (−3ω; ω, ω, ω) = 40×10 −12 ) among all the substituted polyacetylenes synthesized so far. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 277–282, 1999

关键词： metathesis polymerization poly(arylacetylene) conjugated polymer tungsten catalyst molybdenum catalyst nonlinear optical property

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Corrigendum to: prediction of human cDNA from its homologous mouse full-length cDNA and human shotgun database

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FEBS letters 2000年第2-3期471卷 261页

作者： Yoshifumi Fukunishi Harukazu Suzuki Masayasu Yoshino Hideaki Konno Yoshihide Hayashizaki Laboratory for Genome Exploration Research Group Genomic Sciences Center (GSC) and Genome Science Laboratory Tsukuba Life Science Center The Institute of Physical and Chemical Research (RIKEN) 3-1-1 Koyadai Tsukuba Ibaraki 305-0074 Japan CREST (Core Research for Evolutional Science and Technology) of Japan Science and Technology Corporation (JST) 3-1-1 Koyadai Tsukuba Ibaraki 305-0074 Japan

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