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31.
K. Fujii T. Yoshizawa T. Ohyama K. Oto S. Takaoka K. Murase K. Gamo 《Superlattices and Microstructures》2000,27(5-6):353-357
In a vertically coupled dot, it is expected that generalized Kohn theorem is invalid. Then electron–electron interaction can be observed in far-infrared absorption. This interaction depends on the coupling between dots. We fabricated a vertically aligned double-dot array using a double heterostructure to investigate the coupling. The strength of the coupling depends on the confine potential of the dot. In far-infrared magneto-optical absorption measurements under pulsed photoexcitation, we observed peak shift of asymmetry states and increasing of absorption intensity of symmetry states of the dot. This is a result of the confined potential modulation by light. This indicates the possibility of optical control of the coupling. 相似文献
32.
Lawrence Asamoah Adutwum Naoya Kishikawa Kaname Ohyama Shiro Harada Kenichiro Nakashima Naotaka Kuroda 《Analytical and bioanalytical chemistry》2010,398(2):823-829
A sensitive and selective high performance liquid chromatography-peroxyoxalate chemiluminescence (PO-CL) method has been developed
for the simultaneous determination of chlorpheniramine (CPA) and monodesmethyl chlorpheniramine (MDCPA) in human serum. The
method combines fluorescent labeling with 4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl boronic acid using Suzuki coupling reaction with PO-CL detection. CPA and MDCPA were extracted from
human serum by liquid–liquid extraction with n-hexane. Excess labeling reagent, which interfered with trace level determination of analytes, was removed by solid-phase
extraction using a C18 cartridge. Separation of derivatives of both analytes was achieved isocratically on a silica column
with a mixture of acetonitrile and 60 mM imidazole-HNO3 buffer (pH 7.2; 85:15, v/v) containing 0.015% triethylamine. The proposed method exhibited a good linearity with a correlation coefficient of 0.999
for CPA and MDCPA within the concentration range of 0.5–100 ng/mL. The limits of detection (S/N = 3) were 0.14 and 0.16 ng/mL
for CPA and MDCPA, respectively. Using the proposed method, CPA could be selectively determined in human serum after oral
administration. 相似文献
33.
34.
Ohyama Kaname Oyamada Kana Kishikawa Naoya Arakawa Miyuki Ohba Yoshihito Kamino Masahiro Wada Mitsuhiro Nakashima Kenichiro Kuroda Naotaka 《Chromatographia》2009,70(9-10):1501-1504
A new class of chiral stationary phases (CSP) with peptide chiral selectors was prepared by solid-phase synthesis with a tert-butoxycarbonyl-L-amino acid on silica. The type of amino acid that is favorable for this class of CSP is discussed. Using the CSP with the phenylalanine peptide selector, the effect of peptide length on the enantioselectivity was investigated in normal-phase mode. The applicability of the CSP with a phenylalanine peptide to chiral ligand-exchange chromatography was also examined.
相似文献35.
H. Nakata T. Murakami K. Fujii T. Ohyama 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):296
We observed photoluminescence (PL) and photoluminescence excitation (PLE) spectra due to shake-up processes of recombination of two-dimensional electrons and free excitons in a modulation-doped GaAs quantum well at He temperatures. One of the processes is that when an electron recombines with a hole, another electron is excited from the conduction band in GaAs to that in AlGaAs. The other process is that a hole is excited from an acceptor level or the valence band in GaAs to the valence band in AlGaAs during recombination. The electron process is observed in both PL and PLE spectra while the hole process only in the PL spectra. The excitation-intensity dependence of the peak intensity of hole-excited PL is almost quadratic, indicating three-carrier process in the shake-up process. The band offsets of the conduction and valence bands are estimated to be 220 and 146 meV, respectively. 相似文献
36.
Multispectral Image Compression for Improvement of Colorimetric and Spectral Reproducibility by Nonlinear Spectral Transform 总被引:1,自引:0,他引:1
Shanshan Yu Yuri Murakami Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》2006,13(5):346-356
The article proposes a multispectral image compression scheme using nonlinear spectral transform for better colorimetric and
spectral reproducibility. In the method, we show the reduction of colorimetric error under a defined viewing illuminant and
also that spectral accuracy can be improved simultaneously using a nonlinear spectral transform called Labplus, which takes
into account the nonlinearity of human color vision. Moreover, we show that the addition of diagonal matrices to Labplus can
further preserve the spectral accuracy and has a generalized effect of improving the colorimetric accuracy under other viewing
illuminants than the defined one. Finally, we discuss the usage of the first-order Markov model to form the analysis vectors
for the higher order channels in Labplus to reduce the computational complexity. We implement a multispectral image compression
system that integrates Labplus with JPEG2000 for high colorimetric and spectral reproducibility. Experimental results for
a 16-band multispectral image show the effectiveness of the proposed scheme. 相似文献
37.
38.
Two new absorptions which are believed at least partially connected with magnetoplasma resonance within high density exciton drops are observed below 2.2.K in 35GHz cyclotron resonance at germanium under the configuration that E ∥ 〈100〉 and H ∥ 〈001〉. One of them appears very close to the light hole cyclotron resonance signal and is qualitatively interpreted in terms of a simplified magnetoplasma theory, while the other shoots up near zero magnetic field and remains yet unexplained. 相似文献
39.
Kishikawa N Ohkuma M Wada M Ohyama K Ikeda R Nakashima K Kuroda N 《Journal of chromatography. A》2011,1218(20):3002-3006
A novel fluorescent labeling method for alprenolol was developed based on Mizoroki-Heck coupling reaction. We designed and synthesized fluorescent aryl iodide, 4-(4,5-diphenyl-1H-imidazol-2-yl)iodobenzene (DIBI) as a labeling reagent. DIBI has a lophine skeleton carrying an iodide atom acting as fluorophore and reactive center, respectively. In order to evaluate the usefulness of DIBI, a high-performance liquid chromatography (HPLC) with fluorescence detection method was developed for the determination of alprenolol as a model compound of terminal double bond. The fluorescent labeling of alprenolol with DIBI was achieved in the presence of palladium acetate as a catalyst, and the labeled alprenolol was detected fluorometrically. In addition, it was found that the fluorescence of DIBI derivative increased and red shifted when compared with that of DIBI. Furthermore, the proposed method could be applied to determine the alprenolol concentration in rat plasma after administration of alprenolol without interferences from biological components. The detection limit (S/N=3) for alprenolol in rat plasma was 0.74 ng/mL (30 fmol on column). 相似文献
40.
Ohyama K Takemura M 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2008,84(1):17-23
We here describe in detail the characterization and molecular evolution of group II introns in the mitochondrial genome of the liverwort Marchantia polymorpha. We find that 18 introns of the 25 group II introns can be assigned by their similarities to six clusters, indicating an intra-genomic propagation of one ancestral intron each into the respective clusters in the liverwort mitochondrial genome. Interestingly, the intra-genomic propagation of some of these introns occurred only after the evolutionary separation of the bryophytes from the other clades of plants. Finally we report that the maturase-like sequences in the liverwort group II introns have further evolved by horizontal and independent transposition and substitution by analogous sequences from other fungal introns. 相似文献