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排序方式: 共有802条查询结果,搜索用时 15 毫秒
41.
42.
Microdosimetry of neutron field for boron neutron capture therapy at Kyoto university reactor 总被引:1,自引:0,他引:1
Endo S Onizuka Y Ishikawa M Takada M Sakurai Y Kobayashi T Tanaka K Hoshi M Shizuma K 《Radiation protection dosimetry》2004,110(1-4):641-644
Microdosimetric single event spectrum in a human body simulated by an acrylic phantom has been measured for the clinical BNCT field at the Kyoto University Reactor (KUR). The recoil particles resulting from the initial reaction and subsequent interactions, namely protons, electrons, alpha particles and carbon nuclei are identified in the microdosimetric spectrum. The relative contributions to the neutron dose from proton, alpha particles and carbon are estimated to be about 0.9, 0.07 and 0.3, respectively, four depths between 5 and 41 mm. We estimate that the dose averaged lineal energy, yD decreased with depth from 64 to 46 keV microm(-1). Relative biological effectiveness (RBE) of this neutron field using a response function for the microdosimetric spectrum was estimated to decrease from 3.6 to 2.9 with increasing depth. 相似文献
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Production of L-erythrose via L-erythrulose from erythritol using microbial and enzymatic reactions 总被引:4,自引:0,他引:4
Mizanur RM Takeshita K Moshino H Takada G Izumori K 《Journal of Bioscience and Bioengineering》2001,92(3):237-241
A rare aldotetrose, L-erythrose, was produced from erythritol via a two-step reaction. In the first step, complete oxidation of erythritol to L-erythrulose was achieved by using Gluconobacter frateurii IFO 3254. Washed cell suspension of the strain grown on tryptic soy broth (TSB) supplemented with 1% d-sorbitol was used to carry out the transformation reaction at 30 degrees C with shaking at 170 rpm. At 10% substrate concentration, 98% erythritol was converted to L-erythrulose within 48 h. The produced L-erythrulose was then used as a substrate for the production of L-erythrose. The isomerization of L-erythrulose to L-erythrose was carried out using constitutively produced L-ribose isomerase (l-RI) from the mutant strain Acinetobacter sp. DL-28 grown on D-lyxose mineral salt medium. At equilibrium, the yield of L-erythrose from L-erythrulose was 18% and finally 1.7 g L-erythrose was obtained from 10 g erythritol. After a number of simple purification steps, the product was isolated from the reaction mixture by ion-exchange column chromatography (Dowex 50W-X2, Ca2+). The structure of the product was determined after NaBH4 reduction from Infrared (IR) and 13C nuclear magnetic resonance (NMR) spectra. 相似文献
45.
A novel 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS)-vapor annealing method was developed for improving the mechanical strength of porous silica films with a low dielectric constant. TMCTS molecules react with Si-OH groups on the pore wall surfaces to form the polymer network which results in the high hydrophobicity and reinforcement of the silica wall. This method can be used to recover plasma damages induced by etching and ashing in fabricating Cu/low-k interconnects. 相似文献
46.
Hirose T. Saito K. Kojima S. Yao B. Ohsono K. Sato S. Takada K. Ikushima A.J. 《Electronics letters》2007,43(8):443-445
Long-period fibre grating (LPFG) writing by a CO2 laser-annealing using a fibre-drawing process is demonstrated. The fibre in the drawing process was irradiated periodically by a CO2 laser to modify the refractive index. An LPFG with transmission loss of -10 dB and full width at half-maximum of 13 nm has been fabricated. Results show that the refractive index change was induced by stress at the moment of laser annealing 相似文献
47.
Yamazaki E. Inuzuka F. Yonenaga K. Takada A. Koga M. 《Photonics Technology Letters, IEEE》2007,19(1):9-11
A scheme that compensates the waveform distortion induced by nonlinear interchannel crosstalk such as four-wave mixing (FWM) and cross-phase modulation as well as self-phase modulation in phase-locked wavelength-division-multiplexing transmission systems is proposed. Reduction of FWM-induced waveform distortion by controlling the phase relationship between neighbouring channels and its cancellation by precompensation is successfully demonstrated 相似文献
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Abstract We consider two-stage estimation for a fixed-span confidence region about a linear function of mean vectors from π i : N p (μ i , Σ i ), i = 1,…,k (≥2), when Σ i 's have some structures. The purpose of this article is to investigate asymptotic efficiency of the estimation up to the second order in terms of the sample size. An adjustment of the design constant and a proper choice of the initial sample size appearing in the two-stage estimation are proposed to have asymptotic second-order efficiency. Some simulations are carried out to see moderate sample size performances of the proposed two-stage estimation. An example is given for a demonstration. 相似文献