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排序方式: 共有1020条查询结果,搜索用时 46 毫秒
1.
Tomohiro Toigawa Yasuhiro Tsubata Takeshi Kai Takuya Furuta Yuta Kumagai Tatsuro Matsumura 《溶剂提取与离子交换》2021,39(1):74-89
ABSTRACT Absorbed-dose estimation is essential for evaluation of the radiation tolerance of minor-actinide-separation processes. We propose a dose-evaluation method based on radiation permeability, with comparisons of heterogeneous structures seen in the solvent-extraction process, such as emulsions forming in the mixture of the organic and aqueous phases. A demonstration of radiation-energy-transfer simulation is performed with a focus on the minor-actinide-recovery process from high-level liquid waste with the aid of the Monte Carlo radiation-transport code PHITS. The simulation results indicate that the dose absorbed by the extraction solvent from alpha radiation depends upon the emulsion structure, and that from beta and gamma radiation depends upon the mixer-settler-apparatus size. Non-negligible contributions of well-permeable gamma rays were indicated in terms of the plant operation of the minor-actinide-separation process. 相似文献
2.
Genki Saito Yuji Kunisada Takumi Watanabe Xuemei Yi Takahiro Nomura Norihito Sakaguchi Tomohiro Akiyama 《Journal of the American Ceramic Society》2019,102(1):524-532
Carbon-and-oxygen-doped AlN specimens were prepared by combustion synthesis using Al, graphite, and AlN. Graphite addition changed the product color from white to blue. By XRD, the lattice constant increased slightly with increasing carbon content. Blue AlN powder was synthesized with a molar ratio of the diluent AlN of 0.2-0.5 with a fixed graphite content of 0.05. At an AlN molar ratio exceeding 0.6, carbon was not successfully incorporated due to the lower reaction temperature. Calcination at 800°C in air removed residual graphite without changing the crystal structure or product color. Oxygen, nitrogen, and carbon analyses revealed that blue AlN powders contained 0.45-0.54 mass% carbon and 1.4-1.6 mass% oxygen, while the undoped AlN contained 0.021 mass% carbon and 0.94 mass% oxygen. The origin of the white-to-blue color change was investigated via reflection measurements. Blue AlN exhibits an absorption peak at 634 nm (1.96 eV). From first-principles electronic structure calculations, the C-doped AlN and carbon-and-oxygen-doped AlN with a 1:1 ratio could be classified as p-type, whereas the O-doped AlN and 1:3 carbon-and-oxygen-doped AlN were n-type. One reason for the absorption peak at 634 nm may be a transition from the conduction band to an upper unoccupied state. These results suggest the possible control of optical and electronic properties of AlN via carbon-and-oxygen doping. 相似文献
3.
Ultra thin (5 nm) silicon oxynitride (SiON) films were fabricated at a low temperature using nitrogen plasma generated by an inductively coupled plasma system. Effects of post-metalization annealing (PMA) of Al/SiON/Si MOS structure on the electrical properties of the SiON films were studied and correlations between the charge trapping states and the leakage current were established. Positive charge trapping by interface states generated by plasma damage was characterized by the hysteresis in high-frequency capacitance-voltage (C-V) characteristics. Hysteresis was observed to be completely removed by PMA while interface state density at the Si mid band gap reduced from 2.2×1013 to 3.7×1011/eV/cm2 and the oxide fixed charge density changed from 3.3×1012 to −4×1011/cm2. The leakage current also decreased significantly, by more than two orders of magnitude, with PMA. The analysis of the leakage current using trap assisted tunneling (TAT) mechanism indicated that with PMA, the trap energy level in the SiON film becomes shallower from 1.3 to 0.7 eV. The positive trapped charges were observed to be annihilated by PMA and the trapping sites became neutral trap centers in the SiON film. This could lead to the reduction in the leakage current component given rise to by TAT. 相似文献
4.
A high-performance liquid chromatographic (HPLC) separation of diacylglycerol acetates to quantitatite disaturated species
of lung phosphatidylcholine (PC) was studied. The diacylglycerol acetates were applied on a reversed phase column, eluted
by an isocratic solvent, acetonitrile/isopropanol/water (35:15:1, v/v/v) at a flow rate of 1 ml/min, and detected by differential
refractometry (RI). This isocratic HPLC method was useful to separate disaturated species from the others of lung PC.
The quantitative analysis of the molecular species separated by HPLC was studied by RI detection. Chroamtograms obtained by
RI detection and radioactivity determination of diacylglycerol [3H]acetates prepared by [3H]acetic anhydride were almost identical. The RI detector responsed in the same degree for different, authentic standards
of diacylglycerol acetates. The detection limit with RI detection was about 30 nmoles. Molecular species of PCs from human
lung and carcinoma tissues were analyzed by this HPLC method. The contents of disaturated species were very similar to those
reported previously. These results indicate that RI detection is very useful in the nmole range for the quantitative analysis
among the molecular species containing disaturated species. 相似文献
5.
Takayuki Honma Yuichiro Kuroki Tomoichiro Okamoto Masasuke Takata Yukihiro Kanechika Masanobu Azuma Hitofumi Taniguchi 《Ceramics International》2008,34(4):943-946
Aluminum nitride ceramics were prepared by sintering with 0–4.8 mass% of Ca3Al2O6 (C3A) as a sintering additive. The transmittance in the range of 260–550 nm increased with increasing amount of C3A. The cathodoluminescence intensity attributed to oxygen-induced defects decreased with increasing amount of C3A. From the results, the increase of the transmittance in the range of 260–550 nm was considered to be related to the decrease of the oxygen-induced defect density. 相似文献
6.
Keita Ikeue Shingo Ando Tomohiro Mitsuyama Yusuke Ohta Keishi Arayama Akiko Tsutsumi Masato Machida 《Topics in Catalysis》2008,47(3-4):175-180
Lanthanide-based oxysulfides and sulfide, LnTaO3.5S0.5, Ln10OS14 (Ln = La, Pr, Nd, Sm) and La4In5S13, were successively synthesized by sulfurization in a flowing H2S. The sulfurization decreased the band-gap energies from >4 eV to <3eV, because of the formation of occupied S3p orbitals
on the top of valence band. In accordance with the small band gap, the H2 evolution from a 0.01 M Na2S and 0.01 M Na2SO3 solution system was observed under irradiation of light up to >500 nm. The rate of H2 evolution under light irradiation of >500 nm increased in the order of Ni/LaTaO3.5S0.5 < Ru/La10OS14 < Pt/La4In5S13. 相似文献
7.
K Okawa T Aoki K Sano S Harihara A Kitano T Kuroki 《Canadian Metallurgical Quarterly》1998,93(12):2405-2410
OBJECTIVE: We examined the clinical characteristics of ulcerative colitis patients who demonstrated endoscopically discontinuous lesions at the mouth of the appendix. METHODS: Of patients with initial or recurrent active ulcerative colitis who underwent total colonoscopy during the past 3 yr at Osaka City General Hospital, we selected those who had skip lesions in the mouth of the appendix before treatment, and examined their gender, age, disease type, sites of lesions, inflammatory reaction, severity of disease, effects of treatment, and posttreatment course. RESULTS: Discontinuous lesions at the mouth of the appendix were found in 10 patients, who had the following common clinical features: the major lesion was usually present in the lower part of the large bowel including the rectum, many of the patients had suffered an initial attack only, all patients had mild disease, and many of the patients responded quite satisfactorily to treatment with salicylazosulfapyridine. CONCLUSION: Numerous patients with ulcerative colitis with discontinuous lesions at the mouth of the appendix were observed and their clinical characteristics were examined. Determination of the clinical significance of skip lesions in the appendix will contribute to elucidation of the pathogenesis of ulcerative colitis. 相似文献
8.
Toru Ikegami Hideyuki Negishi Dai Kitamoto Keiji Sakaki Tomohiro Imura Masayoshi Okamoto Yasushi Idemoto Nobuyuki Koura Tsuneji Sano Kenji Haraya Hiroshi Yanagishita 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(4):381-387
In order to produce highly concentrated bioethanol by pervaporation using an ethanol‐permselective silicalite membrane, techniques to suppress adsorption of succinic acid, which is a chief by‐product of ethanol fermentation and causes the deterioration in pervaporation performance, onto the silicalite crystals was investigated. The amount adsorbed increased as the pH of the aqueous succinic acid solution decreased. The pervaporation performance also decreased with decreasing pH when the ternary mixtures of ethanol/water/succinic acid were separated. Using silicalite membranes individually coated with two types of silicone rubber, pervaporation performance was significantly improved in the pH range of 5 to 7, when compared with that of non‐coated silicalite membranes in ternary mixtures of ethanol/water/succinic acid. Moreover, when using a silicalite membrane double‐coated with the two types of silicone rubber, pervaporation performance was stabilized at lower pH values. In the separation of bioethanol by pervaporation using the double‐coated silicalite membrane, removal of accumulated substances having an ultraviolet absorption maximum at approximately 260 nm from the fermentation broth proved to be vital for efficient pervaporation. Copyright © 2005 Society of Chemical Industry 相似文献
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