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71.
Akira Nakayama Shinji Nambu Masahiro Inagaki Masahiko Miyauchi Nobuyuki Itoh 《Journal of the American Ceramic Society》1996,79(6):1453-1456
Complex permittivity of polycrystalline AlN was measured over the frequency range 100 MHz to 13 GHz using reflection coefficient and cavity resonator methods. Dielectric relaxation peaks of loss tangent were observed in the frequency range 200 MHz to 3 GHz. The maximum value of loss tangent was ∼200 × 10−4 . Relative permittivities decreased by ∼4% with increased frequency at the region of relaxation peaks. It was shown that these dispersion frequencies were inversely proportional to the grain sizes of AlN and independent of purities and processes. Model calculations for elastic vibration of a single-crystal grain of AlN were performed to investigate the origin of the dielectric dispersion due to piezoelectric effect. The calculated results of elastic sphere and 14-faced-polyhedron models showed a good quantitative agreement with the observed dispersion frequencies, which suggested that the dispersion was due to a piezoelectric vibration of a single grain of AlN ceramics at microwave frequencies. 相似文献
72.
M. Kobayashi Y. Usuki M. Ishii M. Itoh M. Nikl 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2005,540(2-3):381-394
Since we presented our preliminary result (Nucl. Instr. and Meth. A 486 (2002) 170) at SCINT2001, we have continued our efforts to increase the light yield (LY) of PbWO4 scintillators by extending different dopings with an aim to find a possibility of using PbWO4 successfully in Positron Emission Tomography (PET). Overall result obtained for single doping as well as double and tripple co-dopings are summarized, including decay characteristics and radiation hardness. The LY in non-doped PbWO4 crystals with a size of 10×10×(20–30) mm3 is 25–35 photolectrons/MeV (phe/MeV) corresponding to 3–4% of the LY in BGO, when measured with a bialkali photomultiplier during a gate of 1 μs. The maximum LY increased to 49 phe/MeV for single doping with Mo6+, 80 phe/MeV for double co-doping of Mo6++Sb5+, and 85 phe/MeV for tripple co-doping of Mo6++Cd2++Sb5+. The radiation hardness is larger than 105 Gy for each of the samples co-doped with Mo6++Sb5+ and Mo6++Cd2++Sb5+, while it is much poorer in PWO:Mo6+. In each of these co-doped samples, a medium-speed green emission in the microsecond range is created besides the fundamental fast (a few nanoseconds range) blue one, giving a peak at 500 nm in the radioluminescence spectrum similarly as in PWO:Mo6+. 相似文献
73.
Y. Iwadate K. Fukushima Y. Seki K. Itoh T. Fukunaga M. Misawa H. Matsuura A. Kajinami N. Ohtori N. Umesaki H. Kofuji M. Myochin 《Science and Technology of Advanced Materials》2004,5(5-6):683
Although the melt structure of glass-forming ZnCl2 has so far been well studied, there exists quite little information on the structural change due to anion-substitution. In the present work, the short-range structure of ZnCl2–ZnBr2 mixture melts was analyzed systematically by time-of-flight pulsed neutron diffraction techniques, Raman spectroscopy, molecular orbital calculations, and molecular dynamics simulations. According to radial distribution analysis, it was found that there were tetrahedral structural units of ligand-substituted [ZnClnBr4−n]2− (n=0–4) in these melts, not implying the simple mixing of [ZnCl4]2− and [ZnBr4]2− units. Further detailed estimation indicated that the ligand-substituted complex anions were linked with each other by sharing a common anion. 相似文献
74.
Yasuhiro Itoh Takamasa Oshita Kohki Satoh Hidenori Itoh 《Electrical Engineering in Japan》2014,186(1):26-33
The decomposition characteristics of an artificial biogas, which is a mixture of CH 4, CO 2, and H 2 S, using a low‐pressure DC glow discharge have been investigated. It is found that H 2, CO, C 2 H 2, H 2 O, CS 2, and COS are produced from the artificial biogas in the glow discharge. About 65% of the hydrogen atoms in CH 4 are converted into H 2 at an input energy of 800 J, at which CH 4 is completely decomposed, and the decomposition characteristics of the artificial biogas are minimally dependent on the H 2 S additive. Further, H 2 S has a tendency to be decomposed earlier than the other components of the artificial biogas. When the glow discharge is generated in the artificial biogas with H 2 S, some of the carbon atoms are found to deposit on the electrodes and the wall of the discharge chamber. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 26–33, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22304 相似文献
75.
Today many people store music media files in personal computers or portable audio players, thanks to recent evolution of multimedia technologies. The more music media files these devices store, the messier it is to search for tunes that users want to listen to. We propose MusCat, a music browser to interactively search for the tunes according to features, not according to metadata (e.g. title, artist name). The technique firstly calculates features of tunes, and then hierarchically clusters the tunes according to the features. It then automatically generates abstract pictures, so that users can recognize characteristics of tunes more instantly and intuitionally. It finally visualizes the tunes by using abstract pictures. MusCat enables intuitive music selection with the zooming user interface. 相似文献
76.
Ryo Mitsugi Tomoo Itoh Ryoichi Fujiwara 《International journal of molecular sciences》2015,16(7):14997-15008
The human DNAJB3 gene encodes a DNAJ (Heat shock protein 40; Hsp40) homolog, subfamily B, member 3 chaperone protein (DNAJB3), which can be down-regulated in disease conditions, as observed in decreased expression of DNAJB3 mRNA in peripheral blood mononuclear cells (PBMC) of obese patients. Recently, humanized UDP-glucuronosyltransferase (UGT) 1 mice (hUGT1 mice) were developed, in which the introduced human UGT1 gene contained a gene encoding human DNAJB3. In the present study, we analyzed the expression of human DNAJB3 mRNA in hUGT1 mice. Among the examined tissues, the testis had the highest expression of human DNAJB3 mRNA, while the lowest expression was observed in the liver. We found that the pattern of tissue-specific expression of mouse Dnajb3 in hUGT1 mice was very similar to that of human DNAJB3. We further demonstrated that the expression of human DNAJB3 in the liver was significantly reduced in high-fat-diet-fed hUGT1 mice compared to the expression level in the control mice, indicating that the expression of human DNAJB3 in hUGT1 mice could be similarly regulated in disease conditions such as obesity. Humanized UGT1 mice might therefore be useful to investigate the physiological role of human DNAJB3 in vivo. 相似文献
77.
Mary Ann O. Torio Takafumi Itoh Roberta N. Garcia Nobuyuki Maruyama Shigeru Utsumi Evelyn Mae Tecson-Mendoza 《Food research international (Ottawa, Ont.)》2012,45(1):277-282
Sulfhydryl groups and disulfide bond were introduced in mungbean's major storage protein, 8Sα globulin, by protein engineering to improve structural stability and functional properties. Five modified proteins or mutants (F59C, I99C, A213C, one free sulfhydryl group; I99C/A213, one disulfide bridge; F59C/I99C/A213C, one free sulfhydryl group and one disulfide linkage) were expressed in Escherichia coli at a yield similar to that of the unmodified protein or wild type (WT) in soluble form (38%). The number of introduced groups in the mutants was confirmed by Ellman analysis. Mutant and WT proteins exhibited similar elution patterns on gel filtration indicating their trimeric native conformation. Mutants had 2 to 3.8 °C higher Tm values than WT and were digested by chymotrypsin at 52–58% in 60 min but exhibited different digestion patterns. All mutants showed greater hardness of heat-induced gels than WT, especially I99C/A213C and F59C/I99C/A213C. Results indicate the improved structural stability of the modified 8Sα globulin. 相似文献
78.
Hideyuki Inui Toshimasa Itoh Keiko Yamamoto Shin-Ichi Ikushiro Toshiyuki Sakaki 《International journal of molecular sciences》2014,15(8):14044-14057
Polychlorinated dibenzo-p-dioxins (PCDDs) and coplanar polychlorinated biphenyls (PCBs) contribute to dioxin toxicity in humans and wildlife after bioaccumulation through the food chain from the environment. The authors examined human and rat cytochrome P450 (CYP)-dependent metabolism of PCDDs and PCBs. A number of human CYP isoforms belonging to the CYP1 and CYP2 families showed remarkable activities toward low-chlorinated PCDDs. In particular, human CYP1A1, CYP1A2, and CYP1B1 showed high activities toward monoCDDs, diCDDs, and triCDDs but no detectable activity toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD). Large amino acids located at putative substrate-recognition sites and the F-G loop in rat CYP1A1 contributed to the successful metabolism of 2,3,7,8-tetraCDD. Rat, but not human, CYP1A1 metabolized 3,3'',4,4'',5-pentachlorobiphenyl (CB126) to two hydroxylated metabolites. These metabolites are probably less toxic than is CB126, due to their higher solubility. Homology models of human and rat CYP1A1s and CB126 docking studies indicated that two amino acid differences in the CB126-binding cavity were important for CB126 metabolism. In this review, the importance of CYPs in the metabolism of dioxins and PCBs in mammals and the species-based differences between humans and rats are described. In addition, the authors reveal the molecular mechanism behind the binding modes of dioxins and PCBs in the heme pocket of CYPs. 相似文献
79.
Ozone molecules present in high-purity oxygen as a feed gas interact with surfaces and oxygen molecules in an enclosed container. Therefore, some of the ozone molecules are destroyed and the density of ozone decreases with time. An experimental system has been constructed to monitor the temporal decrease in ozone density in a container based on the HgI 254 nm photoabsorption method. Our investigation is focused on the dependence of the effective lifetime of ozone on the wall material at various gas pressures. During the experiments, distortion of the measured decay curves often caused by instabilities in the mercury lamp intensity. We thus attempted to build a simple setup that eliminates the effect of long-term intensity drift. This setup is based on light source intensity monitoring by a separate photodetector and data correction software. This article describes the setup of the experimental apparatus, the results including some preliminary experiments and the temporal variation of the surface loss rate of ozone by repeated measurement along with inspections of the wall surface by Auger electron spectroscopy. 相似文献
80.