分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-03-04
Su, Ning
Liu, Yuanyuan
Wang, Li
Zhang, Jianjie
Zhou, Zhi
Zhao, Xin
Ding, Wenwan
Zheng, Peng
Cheng, Jianping
摘要： Cosmic-ray muons are suitable for non-destructive imaging of large-scale objects. However, due to the low statistics of cosmic-ray muons and the complicated surroundings of transmission muography experiments, trans#2;mission muography often faces challenges such as noise and incomplete data, posing certain difficulties for 3D image reconstruction. This paper applies the SIRT-TV algorithm to muon tomography, conducting a 3D image reconstruction simulation study based on a QinShiHuang tomb phantom. The results indicate that compared to the conventional SIRT algorithm, the SIRT-TV algorithm can effectively suppress artifacts in the reconstructed image, allowing for a more accurate reconstruction of the underground palace. The geometric similarity of the walls reconstructed by SIRT-TV is nearly tripled compared to that of SIRT. This study also discusses the impact of TV-minimization algorithm parameters, and the measurement configurations and durations on the quality of the reconstructed image, providing a reference point for future experiments.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Dong-Wei Bao
Michael S. Brotherton
Pu Du
Jacob N. McLane
T. E. Zastrocky
Kianna A. Olson
Feng-Na Fang
Shuo Zhai
Zheng-Peng Huang
Kai Wang
Bi-Xuan Zhao
Sha-Sha Li
Sen Yang
Yong-Jie Chen
Jun-Rong Liu
Zhu-Heng Yao
Yue-Chang Peng
Wei-Jian Guo
Yu-Yang Songsheng
Yan-Rong Li
摘要： In this third paper of the series reporting on the reverberation mapping (RM) campaign of active galactic nuclei with asymmetric H$\beta$ emission-line profiles, we present results for 15 Palomar-Green (PG) quasars using spectra obtained between the end of 2016 to May 2021. This campaign combines long time spans with relatively high cadence. For 8 objects, both the time lags obtained from the entire light curves and the measurements from individual observing seasons are provided. Reverberation mapping of 9 of our targets has been attempted for the first time, while the results for 6 others can be compared with previous campaigns. We measure the H$\beta$ time lags over periods of years and estimate their black hole masses. The long duration of the campaign enables us to investigate their broad line region (BLR) geometry and kinematics for different years by using velocity-resolved lags, which demonstrate signatures of diverse BLR geometry and kinematics. The BLR geometry and kinematics of individual objects are discussed. In this sample, the BLR kinematics of Keplerian/virialized motion and inflow is more common than outflow.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
摘要： Long noncoding RNAs (IncRNAs), which have emerged in recent years as a new and crucial layer of gene regulators, regulate various biological processes such as carcinogenesis and metastasis. HOTAIR (Hox transcript antisense intergenic RNA), a lncRNA overexpressed in most human cancers, has been shown to be an oncogenic lncRNA. Here, we explored the role of HOTAIR in HeLa cells and searched for proteins regulated by HOTAIR. To understand the mechanism of action of HOTAIR from a systems perspective, we employed a quantitative proteomic strategy to systematically identify potential targets of HOTAIR. The expression of 170 proteins was significantly dys-regulated after inhibition of HOTAIR, implying that they could be potential targets of HOTAIR. Analysis of this data at the systems level revealed major changes in proteins involved in diverse cellular components, including the cytoskeleton and the respiratory chain. Further functional studies on vimentin (VIM), a key protein involved in the cytoskeleton, revealed that HOTAIR exerts its effects on migration and invasion of HeLa cells, at least in part, through the regulation of VIM expression. Inhibition of HOTAIR leads to mitochondrial dysfunction and ultrastructural alterations, suggesting a novel role of HOTAIR in maintaining mitochondrial function in cancer cells. Our results provide novel insights into the mechanisms underlying the function of HOTAIR in cancer cells. We expect that the methods used in this study will become an integral part of functional studies of IncRNAs.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Lv, Xiaoxuan
Hu, Cheng
Gao, Feng
Li, Jiasong
Liu, Xiaohong
Deng, Kai
Zheng, Peng
Gong, Weimin
Wang, Jiangyun
Lv, Xiaoxuan
Hu, Cheng
Gao, Feng
Li, Jiasong
Liu, Xiaohong
Deng, Kai
Zheng, Peng
Gong, Weimin
Wang, Jiangyun
Zhou, Meng
Xia, Andong
摘要： Electron transfer (ET) is widely used for driving the processes that underlie the chemistry of life. However, our abilities to probe electron transfer mechanisms in proteins and design redox enzymes are limited, due to :the lack of methods to site-specifically insert electron acceptors into proteins in vivo. Here we describe the synthesis and genetic incorporation of 4-fluoro-3-nitrophenylalanine (FNO(2)Phe), which has similar reduction potentials to NAD(P)H and ferredoxin, the most important biological reductants. Through the genetic incorporation of FNO2Phe into green fluorescent:protein (GFP) and femtosecond transient absorption measurement, we show that photoinduced electron transfer (PET) from the GFP chromophore to FNO2Phe occurs very fast (within 11 ps), which is comparable to that of the first electron transfer step in photosystem I, from P700* to A(0). This genetically encoded, low-reduction potential unnatural amino acid (UAA) can significantly in-Trove our ability to investigate electron transfer mechanisms in complex reductases and facilitate the design of miniature proteins that mimic their functions.
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