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81.
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
82.
Evaluation of R-curve behavior of ceramic-metal functionally graded materials by stable crack growth
Keiichiro Tohgo Takafumi Suzuki Hiroyasu Araki 《Engineering Fracture Mechanics》2005,72(15):2359-2372
This paper deals with the fracture toughness and R-curve behavior of ceramic-metal functionally graded materials (FGMs). A possibility of stable crack growth in a three-point-bending specimen is examined based on the driving force and resistance for crack growth in FGMs, and the distribution of fracture toughness or R-curve behavior is evaluated on FGMs fabricated by powder metallurgy using partially stabilized zirconia (PSZ) and stainless steel (SUS 304). The materials have a functionally graded surface layer (FGM layer) with a thickness of 1 mm or 2 mm on a SUS 304 substrate. Three-point-bending tests are carried out on a rectangular specimen with a very short crack in the ceramics surface. On the three-point-bending test, a crack is initiated from a short pre-crack in unstable manner, and then it propagates in stable manner through the FGM layer with an increase in the applied load. From the relationship between applied load and crack length during the stable crack growth in the FGM layer, the fracture toughness is evaluated. The fracture toughness increases with an increase in a volume fraction of SUS 304 phase. 相似文献
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84.
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
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87.
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
88.
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
89.
Kenji Imai Koji Takai Tatsunori Hanai Makoto Shiraki Yusuke Suzuki Hideki Hayashi Takafumi Naiki Youichi Nishigaki Eiichi Tomita Masahito Shimizu Hisataka Moriwaki 《International journal of molecular sciences》2014,15(7):11294-11306
Obesity-related metabolic abnormalities, including adipokine imbalance and chronic inflammation, are involved in liver carcinogenesis. Chemerin, a novel adipokine, plays a critical role in adipogenesis, energy metabolism, and inflammation. We evaluated the impact of serum chemerin levels on liver functional reserves in hepatocellular carcinoma (HCC) patients and on the recurrence and prognosis of HCC. This study included 44 patients with any stage of HCC who underwent curative treatment at Gifu Municipal Hospital (Gifu, Japan) between 2006 and 2007. Recurrence-free survival and overall survival were estimated using the Kaplan-Meier method. Serum albumin levels (Pearson’s correlation coefficient; r = 0.3110, p = 0.0399), platelet counts (r = 0.4159, p = 0.0050), and prothrombin times (r = 0.3775, p = 0.0115) were significantly correlated with serum chemerin levels in patients with HCC, and they were inversely correlated with Child-Pugh scores (r = −0.3732, p = 0.0126), serum alanine aminotransferase levels (r = −0.3864, p = 0.0105), and total bilirubin levels (r = −0.4023, p = 0.0068). Among these variables, a multiple comparison test identified that platelet counts and total bilirubin levels were associated with serum chemerin levels (p < 0.0083). No significant correlation was found between serum chemerin levels and recurrence-free survival (p = 0.3691) or overall survival (p = 0.7916). In HCC patients, serum chemerin concentrations were correlated with liver functional reserves and platelet counts, but not with recurrence or prognosis. 相似文献
90.
Takafumi Ishii Takuya Maie Naofumi Kimura Yuki Kobori Yasuo Imashiro Jun-ichi Ozaki 《International Journal of Hydrogen Energy》2017,42(23):15489-15496
The use of carbon cathode catalysts in polymer electrolyte fuel cells instead of the current platinum catalysts is attracting increasing attention. We claim that two factors are important for enhancing the activity of carbon cathode catalysts in the oxygen reduction reaction (ORR): the formation of a nanoshell structure and co-doping with boron and nitrogen. Herein, we investigate the preparation and characterization of active ORR carbon catalysts that combine the above factors. Boron and nitrogen (BN)-doped nanoshell-containing carbon (BN-NSCC) was prepared by carbonizing a mixture of poly(furfuryl alcohol), cobalt phthalocyanine, melamine, and a trifluoroborane–methanol complex at 1000 °C. Transmission electron microscopy and X-ray photoelectron spectroscopy revealed the formation of nanoshell structures with distorted graphitic layers and the introduction of boron and nitrogen atoms, respectively. The ORR activity was evaluated in oxygen-saturated 0.5 mol dm?3 H2SO4 using Koutecky–Levich analysis. The BN-NSCC showed an eight to ten times higher ORR activity than undoped NSCC, with an increased number of electrons participating in the reaction. Tafel analysis revealed a change in the rate-determining step caused by BN-doping. Thus, the combination of a nanoshell structure and co-doping with boron and nitrogen was found to improve the ORR activity of carbon catalysts. 相似文献