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Jiang, Xingfen,Xiu, Qinglei,Zhou, Jianrong,Yang, Jianqing,Tan, Jinhao,Yang, Wenqin,Zhang, Lianjun,Xia, Yuanguang,Zhou, Xiaojuan,Zhou, Jianjin,Zhu, Lin,Teng, Haiyun,Yang, Gui-an,Song, Yushou,Sun, Zhiji Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6
Gadolinium oxysulfide (GOS) is regarded as a novel scintillator for the realization of ultra-high spatial resolution in neutron imaging. Monte Carlo simulations of GOS scintillator show that the capability of its spatial resolution is towards the micron level. Through the time-of-flight method, the light output of a GOS scintillator was measured to be 217 photons per captured neutron, ~100 times lower than that of a ZnS/LiF:Ag scintillator. A detector prototype has been developed to evaluate the imaging solution with the GOS scintillator by neutron beam tests. The measured spatial resolution is ~36 ㎛ (28 line pairs/mm) at the modulation transfer function (MTF) of 10%, mainly limited by the low experimental collimation ratio of the beamline. The weak light output of the GOS scintillator requires an enormous increase in the neutron flux to reduce the exposure time for practical applications.
Yuxin Pan,Xingfen Wang,Hengwei Liu,Guiyin Zhang,Zhiying Ma 한국식물학회 2010 Journal of Plant Biology Vol.54 No.5
UDP-xylose (UDP-Xyl) is a nucleotide sugar used as substrate for producing non-cellulose materials, e. g., hemicellulose and pectic polysaccharide, in the fibers of cotton (Gossypium). Its biosynthesis is catalyzed from UDP-glucuronic acid (UDP-GlcA) by UDP-glucuronate decarboxylase (UXS). Here, we first cloned GhUXS1 in Gossypium hirsutum and Gossypium barbadense based on a transcript-derived fragment that originated from our cDNA–AFLP transcriptome profiling in cotton. GhUXS2and GhUXS3 were also isolated via homology-based cloning. GhUXS nucleotide sequences were identical between the two species, and the deduced amino acid residues had the conserved motif of the UXS family, i.e.,GxxGxxG, Ser residues, and YxxxK. GhUXS1 was expressed in Escherichia coli and generated UXS activity that converted UDP-GlcA to UDP-Xyl. Semiquantitative RT-PCR results showed that GhUXSs transcripts were preferentially expressed during fiber development, from elongation through the stage of secondary cell wall synthesis. Although at the same number of days postanthesis they were more abundant in G. hirsutum, expression was sustained for a longer period in G. barbadense. These different patterns of expression may affect quality and partially explain why the latter species has better fiber strength.
A novel ceramic GEM used for neutron detection
Zhou, Jianrong,Zhou, Xiaojuan,Zhou, Jianjin,Jiang, Xingfen,Yang, Jianqing,Zhu, Lin,Yang, Wenqin,Yang, Tao,Xu, Hong,Xia, Yuanguang,Yang, Gui-an,Xie, Yuguang,Huang, Chaoqiang,Hu, Bitao,Sun, Zhijia,Chen, Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6
A novel ceramic Gas Electron Multiplier (GEM) has been developed to meet the demand of high counting rate for the neutron detection which is an alternative to <sup>3</sup>He-based detector at China Spallation Neutron Source (CSNS). An experiment was performed to measure the neutron transmittance of ceramic-GEM and FR4-GEM at the small angle neutron scattering (SANS) instrument. The result showed the ceramic-GEM has higher transmittance and less self-scattering especially for cold neutrons. One single ceramic GEM could give a gain of 10<sup>2</sup>-10<sup>4</sup> in the mixture gas of Ar and CO<sub>2</sub> (90%:10%) and its energy resolution was about 27.7% by using <sup>55</sup>Fe X ray of 5.9 keV. A prototype has been developed in order to investigate the performances of the ceramic GEM-based neutron detector. Several neutron beam tests, including detection efficiency, spatial resolution, two-dimensional imaging, and wavelength spectrum, were carried out at CSNS and China Mianyang Research Reactor (CMRR). The results show that the ceramic GEM-based neutron detector is a good candidate to measure the high intensity neutrons.
Yang, Jianqing,Zhou, Jianrong,Zhang, Lianjun,Tan, Jinhao,Jiang, Xingfen,Zhou, Jianjin,Zhou, Xiaojuan,Hou, Linjun,Song, Yushou,Sun, XinLi,Zhang, Quanhu,Sun, Zhijia,Chen, Yuanbo Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7
The <sup>n</sup>MCP (Neutron sensitive microchannel plate) combined with advanced readout electronics is widely used in energy selective neutron imaging because of its good spatial and timing resolution. Neutron detection efficiency is a crucial parameter for the <sup>n</sup>MCP. In this paper, a mathematical model based on the oblique cylindrical channel and elliptical pore was established to calculate the neutron absorption probability, the escape probability of charged particles and overall detection efficiency of <sup>n</sup>MCP and analyze the effects of neutron incident position, pore diameter, wall thickness and bias angle. It was shown that when the doping concentration of the <sup>n</sup>MCP was 10 mol%, the thickness of <sup>n</sup>MCP was 0.6 mm, the detection efficiency could reach maximum value, about 24% for thermal neutrons if the pore diameter was 6 ㎛, the wall thickness was 2 ㎛ and the bias angle was 3 or 6°. The calculated results are of great significance for evaluating the detection efficiency of the <sup>n</sup>MCP. In a subsequent companion paper, the mathematical model would be extended to the case of the spatial resolution and detection efficiency optimization of the coating <sup>n</sup>MCP.