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Einstein Probe discovery of EP240408a: A peculiar X-ray transient with an intermediate timescale

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 222-240页

作者： Wenda Zhang Weimin Yuan Zhixing Ling Yong Chen Nanda Rea Arne Rau Zhiming Cai Huaqing Cheng Francesco Coti Zelati Lixin Dai Jingwei Hu Shumei Jia Chichuan Jin Dongyue Li Paul O’Brien Rongfeng Shen Xinwen Shu Shengli Sun Xiaojin Sun Xiaofeng wang Lei Yang Bing Zhang Chen Zhang Shuang-Nan Zhang Yonghe Zhang Jie An David Buckley Alexis Coleiro Bertrand Cordier Liming Dou Rob Eyles-Ferris Zhou Fan Hua Feng Shaoyu Fu Johan P.U.Fynbo Lluis Galbany Saurabh W.Jha Shuaiqing Jiang Albert Kong Erik Kuulkers Weihua Lei Wenxiong Li Bifang Liu Mingjun Liu Xing Liu Yuan Liu Zhu Liu Chandreyee Maitra Alessio Marino Itumeleng Monageng Kirpal Nandra Jeremy Sanders Roberto Soria Lian Tao Junfeng wang song wang Tinggui wang Zhongxiang wang Qingwen Wu Xuefeng Wu Dong Xu Yanjun Xu Suijian Xue Yongquan Xue Zijian Zhang Zipei Zhu Hu Zou Congying Bao Fansheng Chen Houlei Chen Tianxiang Chen Wei Chen Yehai Chen Yifan Chen Chenzhou Cui Weiwei Cui Yanfeng Dai Dongwei Fan Ju Guan Dawei Han Dongjie Hou Haibo Hu Maohai Huang Jia Huo Zhenqing Jia Bowen Jiang Ge Jin Chengkui Li Junfei Li Longhui Li Maoshun Li Wei Li Zhengda Li Tianying Lian Congzhan Liu Heyang Liu Huaqiu Liu Fangjun Lu Laidan Luo Jia Ma Xuan Mao Haiwu Pan Xin Pan Liming song Hui Sun Yunyin Tan Qingjun Tang Yihan Tao Hao wang Juan wang Lei wang Wenxin wang Yilong wang Yusa wang Qinyu Wu Haitao Xu Jingjing Xu Xinpeng Xu Yunfei Xu Zhao Xu Changbin Xue Yulong Xue Ailiang Yan Haonan Yang Xiongtao Yang Yanji Yang Juan Zhang Mo Zhang Wenjie Zhang Zhen Zhang Zhen Zhang Ziliang Zhang Donghua Zhao Haisheng Zhao Xiaofan Zhao Zijian Zhao Hongyan Zhou Yilin Zhou Yuxuan Zhu Zhencai Zhu National Astronomical Observatories Chinese Academy of Sciences School of Astronomy and Space Sciences University of Chinese Academy of Sciences Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Institute of Space Sciences (ICE) CSIC Institut d’Estudis Espacials de Catalunya (IEEC) Max Planck Institute for Extraterrestrial Physics Innovation Academy for Microsatellites Chinese Academy of Sciences Department of Physics University of Hong Kong School of Physics and Astronomy University of Leicester School of Physics and Astronomy Sun Yat-sen University Department of Physics Anhui Normal University Shanghai Institute of Technical Physics Chinese Academy of Sciences Physics Department Tsinghua University Nevada Center for Astrophysics University of Nevada Las Vegas Department of Physics and Astronomy University of Nevada Las Vegas South African Astronomical Observatory Department of Astronomy University of Cape Town Department of Physics University of the Free State Université Paris Cité CNRS Astroparticule et Cosmologie Université Paris Cité CEA Paris-Saclay IRFU/DAp-AIM Department of Astronomy Guangzhou University Cosmic Dawn Center (DAWN) Niels Bohr Institute University of Copenhagen Department of Physics and Astronomy Rutgers the State University of New Jersey Institute for Cosmic Ray Research The University of Tokyo ESA/ESTEC Department of Astronomy School of Physics Huazhong University of Science and Technology INAF-Osservatorio Astrofisico di Torino Sydney Institute for Astronomy School of Physics The University of Sydney Department of Astronomy Xiamen University Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Department of Astronomy University of Science and Technology School of Astronomy and Space Sciences University of Science and Technology of China Institute of Deep Space Sciences Deep Space Exploration Laboratory Department of Astronomy School of Physics and Astronomy Yunnan University Shanghai Astronomical Observatory Chi

We report the discovery of a peculiar X-ray transient,EP240408a,by Einstein Probe （EP） and follow-up studies made with EP,Swift,NICER,GROND,ATCA and other ground-based multiwavelength *** new transient was first detected with Wide-field X-ray Telescope （WXT） on board EP on April 8th,2024,manifested in an intense yet brief X-ray flare lasting for *** flare reached a peak flux of 3.9×10-9erg cm-2s-1in 0.5-4 ke V,～300 times brighter than the underlying X-ray emission detected throughout the *** and more precise follow-up observations by EP/FXT,Swift and NICER confirmed the finding of this new *** X-ray spectrum is non-thermal in 0.5-10 ke V,with a power-law photon index varying *** X-ray light curve shows a plateau lasting for ～4 d,followed by a steep decay till becoming undetectable ～10 d after the initial *** on its temporal property and constraints from previous EP observations,an unusual timescale in the range of 7-23 d is found for EP240408a,which is intermediate between the commonly found fast and long-term *** counterparts have been found in optical and near-infrared,with the earliest observation at 17 h after the initial X-ray detection,suggestive of intrinsically weak emission in these *** demonstrate that the remarkable properties of EP240408a are inconsistent with any of the transient types known so far,by comparison with,in particular,jetted tidal disruption events,gamma-ray bursts,X-ray binaries and fast blue optical *** nature of EP240408a thus remains an *** suggest that EP240408a may represent a new type of transients with intermediate timescales of the order of～10 *** detection and follow-ups of more of such objects are essential for revealing their origin.

关键词： X-ray transients ${\bm~{Einstein~~Probe}}$

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Steric Hindrance Ligand Strategy to Aluminum Porphyrin Catalyst for Completely Alternative Copolymerization of CO_2 and Propylene Oxide

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Chinese Journal of Polymer Science 2018年第2期36卷 252-260页

作者： Chun-Wei Zhuo Yu-Sheng Qin Xian-Hong wang Fo-song wang Key Laboratory of Polymer Ecomaterial Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China Hefei 230026China

Aluminum porphyrin complexes are heavy-metal-free and soil-tolerant green catalysts for the copolymerization of CO2 and propylene oxide（PO）, but they suffer from relatively poor poly（propylene carbonate）（PPC） selectivity. Herein, steric hindrance porphyrin ligand was used to enhance the PPC selectivity. Typically, a bulky anthracene-like group was incorporated into the porphyrin ring to form 5,10,15,20-tetra（1,2,3,4,5,6,7,8-octahydro-1,4：5,8-dimethanoanthracen-9-yl）porphyrin, the aluminum porphyrin complex with this ligand, in combination with bis（triphenylphosphine）iminium chloride as a co-catalyst, produced completely alternate PPC. Additionally, the obtained PPC showed high regioselectivity, with a head-to-tail linkage content（HT） of 92%. Therefore, we demonstrated that introduction of bulky steric ligand into the porphyrin ring could reduce the propylene oxide homopolymerization activity leading to excellent PPC selectivity, and improve regioselectivity for the PO ring-opening during the copolymerization.

关键词： Carbon dioxide Propylene oxide Porphyrin Aluminum Steric hindrance

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IVMS:An immersive virtual meteorological sandbox based on WYSIWYG

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Visual Informatics 2023年第4期7卷 100-109页

作者： Hao Hu song wang Yonghui Chen School of Computer Science and Technology Southwest University of Science and TechnologyChina

A novel approach to visually represent meteorological data has emerged with the maturation of Immersive Analytics(IA).We have proposed an immersive meteorological virtual sandbox as a solution to the limitations of 2D analysis in expressing and perceiving *** innovative visual method enables users to interact directly with data through non-contact aerial gestures(NCAG).Referring to the“What you see is what you get”concept in scientific visualization,we proposed a novel approach for the visual exploration of meteorological data that aims to immerse users in the analysis *** hope this approach can inspire immersive visualization techniques for other types of geographic data as ***,we conducted a user questionnaire to evaluate our system and *** evaluation results demonstrate that our system effectively reduces cognitive burden,alleviates mental workload,and enhances users’retention of analysis findings.

关键词： Immersive Analytics WYSIWYG Virtual sanbox Non-contact aerial gestures Immersive meteorological visualization

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Sharp Chandra View of ROSAT All-Sky Survey Bright Sources I. Improvement of Positional Accuracy

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Research in Astronomy and Astrophysics 2016年第12期16卷 67-74页

作者： Shuang Gao song wang Ji-Feng Liu Department of Astronomy Beijing Normal University Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences College of Astronomy and Space Sciences University of Chinese Academy of Sciences

The ROSAT All-Sky Survey （RASS） represents one of the most complete and sensitive soft X- ray all-sky surveys to date. However, the deficient positional accuracy of the RASS Bright Source Catalog （BSC） and subsequent lack of firm optical identifications affect multi-wavelength studies of X-ray sources. The widely used positional errors σpos based on the Tycho Reference Catalog （Tycho-1） have previously been applied for identifying objects in the optical band. The considerably sharper Chandra view covers a fraction of RASS sources, whose ~rpos could be improved by utilizing the sub-arcsec positional accuracy of Chandra observations. We cross-match X-ray objects between the BSC and Chandra sources extracted from the Advanced CCD Imaging Spectrometer （ACIS） archival observations. A combined list of counter- parts （BSCxACIS） with Chandra spatial positions weighted by the X-ray flux of multiple counterparts is employed to evaluate and improve the former identifications of BSC when used with other surveys. Based on these identification evaluations, we suggest that the point-source likeness of BSC sources and INS （iso- lated neutron star） candidates should be carefully reconsidered.

关键词： catalogs -- surveys -- X-rays: general -- X-rays: stars

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Gaia calibrated UV luminous stars in LAMOST

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Research in Astronomy and Astrophysics 2018年第12期18卷 123-130页

作者： Yu Bai Ji-Feng Liu song wang Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences College of Astronomy and Space Sciences University of Chinese Academy of Sciences

We take advantage of Gaia Data Release 2 to present 275 and 1774 ultraviolet luminous stars in the far ultraviolet(FUV) and near ultraviolet(NUV), *** stars exceed their expected values by 5σ with respect to over one million ultraviolet stars in the log g *** extinction is corrected with a 3 D dust *** order to limit the Lutz-Kelker bias to an insignificant level, we select stars with relative uncertainties in luminosity less than 40% and trigonometric parallaxes less than 20%.We cross-identified our sample with the catalogs of RR Lyr stars and possible white dwarf main-sequence binaries, and find they compose ～62% and ～16% of our sample in the FUV and NUV, *** catalog provides a unique sample to study stellar activity, spectrally unresolved compact main-sequence binaries and variable stars.

关键词： stars:activity stars:general ultraviolet:stars

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Chinese Marine Economy Development: Dynamic Evolution and Spatial Difference

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Chinese Geographical Science 2018年第1期28卷 111-126页

作者： SUN Caizhi LI Xin ZOU Wei wang song wang Zeyu Center for Studies of Marine Economy and Sustainable Development Liaoning Normal University School of Foreign Languages Liaoning Normal University

This study focuses on China's coastal area and its marine economic development. Applying the information diffusion method, the study establishes a kernel density function and its decomposition using a marine economic per capita as the index of the model to depict the dynamic evolution law and the internal influential factors of the Chinese marine economy during 1996–2013. The relative development rate was introduced to analyze the spatial differences in the marine economy's development. In this way, space and time dimensions fully characterized the evolution of the Chinese marine economy. Additionally, the influence of growth and inequality in the process of its development can be analyzed. The study shows that the Chinese marine economy as a whole has been growing, and regional marine economic development is relatively coordinated. In addition, the marine economy began to develop even more rapidly after 2004. There are three factors affecting the dynamic evolution of China's marine economy: first, the most influential mean effect, followed by, second, the variance effect, and third, the least influential residual effect. The biggest influence on the dynamic evolution of the marine economy is the improvement of the development level of the marine economy in the coastal area. Meanwhile, due to the existence of inequality, provinces at higher development levels are more dispersed. Furthermore, the existence of the residual effect weakens the influence of the mean effect, and the influence on the dynamic evolution of the marine economy continuously increases. In the analysis of the influencing factors of the evolution and spatial difference of marine economic development, the level of opening to the outside world, the level of investment in fixed assets and the industrial structure have a positive role in promoting economic development. However, capital investment in scientific human research has a negative correlation with economic development, and does not pass the s

关键词： information diffusion kernel density function decomposition marine economic output per capita coastal area

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Analysis of landslide damage caused by the 2008 Wenchuan earthquake using strong motion data: A case study in the Beichuan county town

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Earthquake Science 2012年第4期25卷 307-313页

作者： Xiuying wang Gaozhong Nie song wang Institute of Crustal Dynamics China Earthquake Administration Institute of Geology China Earthquake Administration China Earthquake Networks Center

The county town of Beichuan county, China, experienced catastrophic destruction due to landslides induce by the 2008 Wenchuan earthquake. In consideration of the special location of the county town, this paper selected the landslides induced in the town as representative of large-scale near-rupture landslides, and quantitatively analyzed why the landslide damage was so destructive in the town by using strong motion data obtained from the Wenchuan earthquake in the Longmenshan area. Three methods were employed to estimate the landslide damage using strong motion data. （1） Peak ground accelerations （PGAs） on the hanging wall were used to evaluate the PGAs on the landslide sites in the town. The evaluated average PGAs were all greater than I g, indicating that the ground motion intensity was very strong during the earthquake. （2） Acceleration time histories, from another station with similar geological conditions to the town, were used to evaluate the critical acceleration changing range, and the estimated values showed the geological conditions were very susceptible to earthquakes. （3） Acceleration time histories, from two stations on the hanging and foot walls of the rupture, and near the town, were used to calculate the Newmark displacements, and all the evaluated displacements indicated that landslides were very likely. The results show that the slopes, susceptible to earthquakes in the Beichuan county town, were easily triggered under such strong ground-motion intensity and developed into large-scale catastrophic events.

关键词： Wenchuan earthquake landslide strong motion evaluation critical acceleration

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Precipitation process and its effects on properties of aging Cu–Ni–Be alloy

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Rare Metals 2013年第4期32卷 332-337页

作者： Li-Jun Peng Bai-Qing Xiong Guo-Liang Xie Qiang-song wang song-Bai Hong State Key Laboratory of Nonferrous Metals & Process General Research Institute for Nonferrous Metals Yingtan Shine Electric Metal Material Co. Ltd

The precipitation process of aged Cu-Ni-Be alloy was investigated by X-ray diffraction （XRD）, trans- mission electron microscopy （TEM）, and high-resolution transmission electron microscopy （HRTEM）. The tensile strength, yield strength, and electronic conductivity of this alloy after aging were also studied. The precipitation sequence of the C17510 alloy aged at 525 ℃ is supersat-urated solid solution→G.P zones→ γ″-γ′→ γ. This transformation can be achieved by the accumulation of Be-atom layers. The G.P zones are composed of disk-shaped monolayers of Be atoms, which are formed on （001） matrix planes. The intermediate γ″ precipitate is nucleated in the G.P zones. The γ″ and γ′ precipitates have the same orientation relationship with matrix, e.g., （110）p｜｜（100）M,[001]p｜｜[001]M. The tensile strength of specimen shows a maximum during the aging process and then continuously decreases if the specimen is over aged. The strengthening effect of γ′ phase precipitated in aging at 525 ℃ for 4 h is calculated to be 436 MPa according to the Orowan strengthening, which is quite consistent with the experimental data.

关键词： Precipitation process C17510 alloy Metastable phases Strengthening mechanism

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SYNERGISTIC EFFECTS OF NOVOLAC-BASED CHAR FORMER WITH A PHOSPHORUS/NITROGEN-CONTAINING FLAME RETARD ANT IN POLYAMIDE 6

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Chinese Journal of Polymer Science 2012年第1期30卷 72-81页

作者： Wei-cheng Xiong Li Chen De-yi wang Fei song Yu-zhong wang Center for Degradation an-d Flame--Retardant Polymeric Materials College of-Chemistry State Key Laboratory of Polymer Materials Engineering National Engineering Laboratory of Eco-Friendly Polymeric Materials （Sichuan） Sichuan University Chengdu 610064 China

The synergistic effect of phosphorus oxynitride（PON） with a novolac-based char former modified by salification （NA-metal salt） on the flame retardance of polyamide 6（PA6） was *** this purpose,various flame-retardant PA6 systems were melt-compounded with PON,PON/NA,PON/NA-V_2O_5 and PON/NA-Fe_2O_3,and their flame retardance was evaluated by measuring the limiting oxygen index（LOI） values and UL-94 vertical burning *** results showed that,compared with the PA6/PON/NA system,the combination of two char formers（NA-V_2O_5,NA-Fe_2O_3） with PON could obviously improve the char formation and flame retardance of *** flame retardance and cone calorimetric analyses showed the stronger synergism as well as the better flame retardant performance of PON/NA-Fe_2O_3 flame retardant system. The effects of different char formers on the flame retardance and thermal stability of this system were also discussed.

关键词： Polyamide Flame retardance Novolac resin Synergistic effect

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ELECTROSTATIC INTERACTION HYBRIDS FROM WATER-BORNE CONDUCTIVE POLYANILINE AND INORGANIC PRECURSOR CONTAINING CARBOXYL GROUP

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Chinese Journal of Polymer Science 2007年第2期25卷 181-186页

作者： Jing Luo Xian-hong wang Ji Li Xiao-jiang Zhao Fo-song wang State Key Laboratory of Polymer Physicsand Chemistry Changchun Institute of Applied Chermstry Graduate School of Chinese Academy of Sciences Changchun 130022 China

Electrostatic interaction conductive hybrids were prepared in water/ethanol solution by the sol-gel process from inorganic sol containing carboxyl group and water-borne conductive polyaniline （cPANI）. The electrostatic interaction hybrids film displayed 1-2 orders of magnitude higher electrical conductivity in comparison with common hybrids film, showing remarkable conductivity stability against water soaking. Most strikingly, it displayed ideal electrochemical activity even in a solution with pH = 14, which enlarged the conducting polyaniline application window to strong alkaline media.

关键词： Water-borne conductive polyaniline Sol-gel Electrostatic interaction.

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