分类： 物理学 >> 核物理学 提交时间： 2023-09-04
Li, Yunxiang
Meng, Lu
Huang, Zinan
Li, Song
Wang, Disi
Liu, Bo
Zhang, Youpeng
Peng, Tianji
Zhang, Lu
Su, Xingkang
Jiang, Wei
摘要：Steam generator tube rupture (SGTR) accident is an important scenario needed to be considered in the safety analysis of lead-based fast reactors. When the steam generator tube breaks close to the main pump, water vapor will enter the reactor core, resulting in a two-phase flow of heavy liquid metal and water vapor in fuel assemblies. The thermal-hydraulic problems caused by the SGTR accident may seriously threaten reactor core’s safety performance. In this paper, the open source CFD calculation software OpenFOAM was used to encapsulate the improved Euler method into the self-developed solver LBEsteamEulerFoam. By changing different heating boundary conditions and inlet coolant types, the two-phase flow in the fuel assembly with different inlet gas content was simulated under various accident conditions. The calculation results show that the water vapor may accumulate in edge and corner channels. With the increase of inlet water vapor content, outlet coolant velocity increases gradually. When the inlet water vapor content is more than 15%, the outlet coolant temperature rises sharply with strong temperature fluctuation. When the inlet water vapor content is in the range of 5% to 20%, the upper part of the fuel assembly will gradually accumulate to form large bubbles. Compared with the VOF method, Euler method has higher computational efficiency. However, Euler method may cause an underestimation of the void fraction, so it still needs to be calibrated with future experimental data of the two-phase flow in fuel assembly.
分类： 物理学 >> 核物理学 分类： 天文学 >> 天文仪器与技术 提交时间： 2023-08-29
Wan, Qiang
Guo, Jianhua
Xu, Xing
Wang, Shen
Zhang, Yongqiang
Hu, Yiming
Zhang, Yan
Pan, Xu
Li, Xiang
Yue, Chuan
Jiang, Wei
Cui, Yuxin
Chen, Dengyi
摘要：In the future, the Very Large Area gamma-ray Space Telescope (VLAST) is expected to observe high-energy electrons and gamma rays in the MeV to TeV range with unprecedented acceptance. As part of the detector suite, a high-energy imaging calorimeter (HEIC) is currently being developed as a homogeneous calorimeter that utilizes long bismuth germanate (BGO) scintillation crystals as both absorbers and detectors. To accurately measure the energy deposition in the BGO bar of HEIC, a high-dynamic-range readout method using a silicon photoMultiplier (SiPM) and multiphotodiode (PD) with different active areas has been proposed. A prototype readout system that adopts multichannel charge measurement ASICs was also developed to read out the combined system of SiPMs and PDs. Preliminary tests confirmed the feasibility of the readout scheme, which is expected to have a dynamic range close to 106.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Gao, Shijuan
Li, Jiandong
Song, Liping
Sheng, Chunjie
Liu, Dong
Jiang, Wei
Chen, Shuai
Huang, Wenlin
Wu, Jiaoxiang
Yao, Chen
Chen, Huiming
Liu, Ran-Yi
Chen, Shuai
Huang, Wenlin
Huang, Wenlin
Teng, Yan
摘要：Influenza A viruses (IAVs) rely on host factors to support their life cycle, as viral proteins hijack or interact with cellular proteins to execute their functions. Identification and understanding of these factors would increase our knowledge of the molecular mechanisms manipulated by the viruses. In this study, we searched for novel binding partners of the influenza A virus NS2 protein, the nuclear export protein responsible for overcoming host range restriction, by a yeast two-hybrid screening assay and glutathione S-transferase-pulldown and coimmunoprecipitation assays and identified AIMP2, a potent tumor suppressor that usually functions to regulate protein stability, as one of the major NS2-binding candidates. We found that the presence of NS2 protected AIMP2 from ubiquitin-mediated degradation in NS2-transfected cells and AIMP2 functioned as a positive regulator of IAV replication. Interestingly, AIMP2 had no significant effect on NS2 but enhanced the stability of the matrix protein M1. Further, we provide evidence that AIMP2 recruitment switches the modification of M1 from ubiquitination to SUMOylation, which occurs on the same attachment site (K242) on M1 and thereby promotes M1-mediated viral ribonucleoprotein complex nuclear export to increase viral replication. Collectively, our results reveal a new mechanism of AIMP2 mediation of influenza virus replication. IMPORTANCE Although the ubiquitination of M1 during IAV infection has been observed, the precise modification site and the molecular consequences of this modification remain obscure. Here, we demonstrate for the first time that ubiquitin and SUMO compete for the same lysine (K242) on M1 and the interaction of NS2 with AIMP2 facilitates the switch of the M1 modification from ubiquitination to SUMOylation, thus increasing viral replication.
分类： 物理学 >> 核物理学 分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2023-09-12
Yang, Gaole
An, Zhendong
Jiang, Wei
Li,Xiankai
Qiu, Weiwei
Liao, Zhengfa
Zhuang, Ziyue
Zhang, Xiaoping
Chen,Shengli
Xiao, Erxi
Fang,Xiao
Li,XinXiang
Hu, Xinrong
Jiang, Bing
Wang, Jincheng
Ren, Jie
Luo, Wen
Zhu, ZhiChao
Lan, Haoyang
Cao, Zongwei
摘要：The neutron capture cross sections (${n, upgamma}$) of Bromine was performed with the time-of-flight (TOF) technique at the Back-n facility of the China Spallation Neutron Source (CSNS). Prompt $ upgamma$-rays originating from neutron-induced capture events were detected by four C${}_6$D${}_6$ detectors. The pulse height weighting technique (PHWT) and the double-bunch unfolding method based on the Bayesian theory were used in the data analysis. To obtain reliable measurement results, background deductions, normalization, and corrections were carefully considered. The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the resolved resonance region (RRR). The average cross sections in unresolved resonance region the was obtained from 10 to 400 keV. The experimental results were compared with the data of several evaluated libraries and previous experiments in the resolved and unresolved resonance region. The TALYS code was used to describe the average cross sections in the unresolved resonance region. Astrophysical Maxwell average cross sections (MACSs) of ${}^{79,81}$Br from $ kT $ = 5 to 100 keV was calculated over a sufficiently wide range of neutron energies. At a thermal energy of $kT=30$ keV, the MACS value for ${}^{79}$Br 638$ pm$64 mb is in good agreement with the KADoNiS recommended value. By contrast, the value of 293$ pm$29 mb for ${}^{81}$Br is substantially higher than those of the evaluated database and the KADoNiS recommended value.
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