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The GECAM ground search system for gamma-ray transients

Science China(physics,Mechanics & Astronomy) 2025年第3期68卷 161-174页

作者： Ce Cai Yan-Qiu Zhang Shao-Lin Xiong Ping Wang Jian-Hui Li Xiao-Bo Li Cheng-Kui Li Yue Huang Shi-Jie Zheng Li-Ming Song Shuo Xiao Qi-Bin Yi Yi Zhao Sheng-Lun Xie Rui Qiao Yan-Qi Du Zhi-Wei Guo Wang-Chen Xue Chao Zheng Jia-Cong Liu Chen-Wei Wang Wen-Jun Tan Yue Wang Jin-Peng Zhang Chao-Yang Li Guo-Ying Zhao Xiao-Yun Zhao Xiao-Lu Zhang Zhen Zhang Wen-Xi Peng Xiang Ma Jing-Yan Shi Dong-Ya Guo Jin Wang Xin-Qiao Li Xiang-Yang Wen Zheng-Hua An Fan Zhang college of physics and Hebei Key Laboratory of Photophysics Research and Application Hebei Normal UniversityShijiazhuang050024China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing100049China University of Chinese Academy of Sciences Beijing100049China School of physics and Electronic Science Guizhou Normal UniversityGuiyang550001China guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang550001China School of physics and Optoelectronics Xiangtan UniversityXiangtan411105China School of Computer and Information Dezhou UniversityDezhou253023China institute of Astrophysics Central China Normal UniversityWuhan430079China

In the era of time-domain,multi-messenger astronomy,the detection of transient events on the high-energy electromagnetic sky has become more important than *** gravitational wave high-energy electromagnetic counterpart all-sky monitor(GECAM)is a dedicated mission to monitor gamma-ray transients,launched in December,2020.A real-time on-board trigger and location software,using the traditional signal-to-noise ratio(SNR)method for blind search,is constrained to relatively bright signals due to the limitations in on-board computing resources and the need for real-time *** this work,we developed a ground-based pipeline for GECAM to search for various transients,especially for weak bursts missed by on-board *** pipeline includes both automatic and manual mode,offering options for blind search and targeted *** targeted search is specifically designed to search for interesting weak bursts,such as gravitational wave-associated gamma-ray bursts(GRBs).From the ground search of the data in the first year,GECAM has been triggered by 54 GRBs and other transients,including soft gamma-ray repeaters,X-ray binaries,solar flares,terrestrial gamma-ray *** report the properties of each type of triggers,such as trigger time and light *** this search pipeline and assuming a soft Band spectrum,the GRB detection sensitivity of GECAM is increased to about 1.1×10^(-8)erg cm^(-2)s^(-1)(10-1000 ke V,burst duration of 20 s).These results demonstrate that the GECAM ground search system(both blind search and targeted search)is a versatile pipeline to recover true astrophysical signals which were too weak to be found in the on-board search.

关键词： gamma-ray sources gravitational waves data analysis gamma-ray telescopes

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A new exceptionally preserved corystosperm wood from the Jurassic of East Asia

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Science China Earth Sciences 2025年第3期68卷 803-810页

作者： Zikun JIANG Ning TIAN Yongdong WANG Fangyu LI Junling PEI Dieter UHL Ya LI Hao WU Zhenguo NING Ruiying HAO Chinese Academy of Geological Sciences college of Palaeontology Shenyang Normal University Nanjing institute of Geology and Palaeontology Chinese Academy of Sciences college of Resources and Environmental Engineering Guizhou University East China University of Technology Senckenberg Research institute and Natural History Museum Frankfurt Zhejiang Museum of Natural History Department of Natural Resources of Shandong Province

Corystosperms, an extinct group of “seed ferns” that lived from the late Permian to the Cretaceous or Eocene, are significant for seed plant phylogeny for their unique roles in partially resolving the long-standing question of angiosperm origins.A new fossil wood taxon, Fengweioxylon sinense gen. et sp. nov. is reported here based on exceptionally preserved wood material from the Jurassic in western Liaoning, China, whose peculiar wood structure enables it to be recognized as the first unequivocal fossil wood record of a corystosperm plant in Laurasia. The anatomical structures of this corystosperm wood show gymnospermous characters. The discovery of the new specimen will provide more anatomical evidence for understanding the systematic and affinity of this seed plants.

关键词： Corystosperms Fossil wood Laurasia Jurassic

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Probing the special angle in twisted bilayer MoS_(2)via angle-dependent scanning tunneling microscopy studies

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Science China(physics,Mechanics & Astronomy) 2025年第2期68卷 153-160页

作者： Xueying Liu Shiying Liu Yulong Xiao Chang Xu Jiaxin Wu Kaihui Li Si-Yu Li Anlian Pan Key Laboratory for Micro-Nano physics and Technology of Hunan Province Hunan Institute of Optoelectronic Integration and College of Materials Science and EngineeringHunan UniversityChangsha410082China School of physics and Electronics Hunan Normal UniversityChangsha410081China

Twisted transition metal dichalcogenides(TMDs)homo-bilayers host unique quantum properties,which can be tuned by interlayer twist angleθ.However,the systematic evolution of their typical electronic properties with respect to the twist angleθ,which is crucial for identifying the“special angle”analogous to the“magic angle”of twisted bilayer graphene in correlation physics studies,remains incompletely ***,via scanning tunneling microscopy(STM)and spectroscopy(STS),we investigate the variation of the moirépotential,flat band,and layer polarization characteristics across a wide range of twist angleθin twisted bilayer MoS_(2)(TB-MoS_(2)).The moirépotential of the valence band exhibits a non-monotonic variation withθ,peaking at a maximum value up to 204 me Vatθ~1.7°.Concurrently,at the sameθ,the bandwidth of the flat band at theΓ_(V)point of the valence band attains its minimum,precisely signifying the“special angle”θ_(c)~1.7°in TB-MoS_(2).Interestingly,layer polarization in the moirésuperlattice is spatially visualized through the distribution of local density of states(LDOS)at the energies of bothΓ_(V)and K_(V)points of the valence band,where the polarization degree at theΓ_(V)point demonstrates a close dependency onθ.Our findings deepen understanding of twist-angle effect in TMDs,advancing both fundamental physics and practical application.

关键词： twisted bilayer MoS_(2) flat band moirépotential twist-angle dependence scanning tunneling microscopy

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Effect of acid fracturing fluid modifying coal microstructure stimulated by ultrasonic

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International Journal of Mining Science and Technology 2025年第2期35卷 275-293页

作者： Shaojie Zuo Rui Gan Zhijie Wen Liang Zhang Zhizhong Jiang Fuping Zhao Chengwei Liu Kun Li Zhiyuan Xu college of Mining Guizhou UniversityGuiyang 550025China Shandong Key Laboratory of Mining Disaster Prevention and Control Shandong University of Science and TechnologyQingdao 266590China School of Emergency Management Xihua UniversityChengdu 610039China guizhou Research institute of Oil&Gas Exploration and Development Engineering Guiyang 550022China Liupanshui normal University Liupanshui 553000China

The combination of ultrasonic and acid fracturing fluid can strengthen the modification effect on the micropore structure of the coal matrix,thereby enhancing the efficiency of the acid fracturing *** this research,acetic acid was utilized to formulate acid fracturing fluids with varying concentrations,and the evolutionary traits of both the acid fracturing fluids and ultrasonic waves in relation to coal samples were *** functional group structure,mineral composition,micropore structure and surface morphology of coal samples were characterized by FTIR,XRD,N_(2)adsorption at low temperature and *** results showed that aromatics(I)and branching parameters(CH_(2)/CH_(3))were reduced by 81.58%and 88.67%,respectively,after 9%acetic acid *** acid can dissolve carbonates and clay minerals in coal,create new pores,and increase porosity,pore volume and pore fractal *** modification by 7%acetic acid,the pore volume increased by 5.7 *** observation shows that the diameter of coal surface holes increases,EDS scanning shows that the content of mineral elements in coal decreases,the connectivity of coal holes increases,and the holes *** findings of this research offer theoretical direction for optimizing ultrasonic-enhanced acid fracturing fluid modification.

关键词： Acidic fracturing fluid Ultrasonic Coalbed methane Microstructure

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Compact source for quadripartite deterministically entangled optical fields

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Fundamental Research 2025年第1期5卷 132-137页

作者： Yanhong Liu Yaoyao Zhou Liang Wu Jiliang Qin Zhihui Yan Xiaojun Jia Department of physics Taiyuan Normal UniversityJinzhong 030619China institute of Computational and applied physics Taiyuan Normal UniversityJinzhong 030619China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China college of Information Engineering Shanxi Vocational University of Engineering Science and TechnologyJinzhong 030619China

Since entangled multiple optical fields were identified as the building blocks of quantum networks,the quadripartite entangled optical fields have been produced by using four degenerate optical parametric amplifiers or two nondegenerate optical parametric amplifiers(NOPAs).However,realizing an efficient and compact source for multiple quantum users has remained an outstanding challenge,hindering their practical ***,we proposed a compact and feasible scheme to deterministically entangle four spatially separated optical fields,employing only a single ***,two-sided output NOPA-based optical fields were coupled on a beam splitter network to form the quadripartite entangled state,causing the deterministic generation of both the Greenberger–Horne–Zeilinger(GHZ)and the linear cluster states in this compact entanglement *** also obtained the optimal experimental parameters based on the simulation results,thereby providing a direct reference for experimental *** findings propose that the resultant GHZ and linear cluster states can be potentially applied in quantum-enhanced information science,specifically in quantum secret sharing,controlled quantum teleportation networks,and quantum-entangled atomic ensemble networks.

关键词： Quadripartite entanglement Single NOPA Compact source GHZ state Cluster state

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Holographic images of a charged black hole in Lorentz symmetry breaking massive gravity

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Science China(physics,Mechanics & Astronomy) 2025年第2期68卷 59-72页

作者： Xiao-Xiong Zeng Li-Fang Li Pan Li Bo Liang Peng Xu college of physics and Electronic Engineering Chongqing Normal UniversityChongqing 401331China Department of Mechanics Chongqing Jiaotong UniversityChongqing 400074.China Center for Gravitational Wave Experiment National Microgravity LaboratoryInstitute of MechanicsChinese Academy of SciencesBeijing 100190China Lanzhou Center of Theoretical physics Lanzhou UniversityLanzhou 730000China

Using the AdS/CFT correspondence,this paper investigates the holographic images of a charged black hole within the context of Lorentz symmetry breaking massive *** photon rings,luminosity-deformed rings,or light points from various observational perspectives are *** also study the influences of both the chemical potential and temperature on the Einstein *** the previous work,which primarily examines the effect of chemical potential on ring radius at high temperatures and find no change in the radius with varying chemical potential,we also investigate the effect of chemical potential on the ring radius at low temperature besides at high *** findings indicate that at low temperatures,the photon ring radius decreases with increasing of chemical potential,while at high temperatures,the results are consistent with previous ***,we explore the impact of the model parameterλon the Einstein ring radius and find the the ring radius increases as the model parameterλ*** interestingly,for the large chemical potential,u=1,the temperature dependence of the photon ring radius is reversed forλ=2 andλ=***,for a small chemical potential u=0.1,the temperature dependence of the Einstein ring stays the same asλ=2 andλ=4.

关键词： AdS/CFT correspondence holographic images massive gravity black holes

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Visible-light-responsive homologous heterostructure of oxynitrides constructed to boost charge separation and water splitting

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Science China Chemistry 2025年第1期68卷 186-191页

作者： Hai Zou Yunfeng Bao Xueshang Xin Yu Qi Tengfeng Xie Fuxiang Zhang State Key Laboratory of Catalysis Dalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China School of Chemistry and Chemical Engineering Liaoning Normal UniversityDalian 116029China college of Chemistry Jilin UniversityChangchun 130012China

Constructing typeⅡheterostructures represents a widely recognized strategy for enhancing charge separation and photocatalytic efficiency,but it remains challenging to fabricate homologous heterostructures based on visible-light-responsive semiconductors,especially for popularly investigated(oxy)nitrides with low thermal ***,we synthesized a homologous heterostructure(denoted as YTON_H)based on the oxynitrides of YTaO_(4-x)N_(y)and YTa ON_(2).This heterostructure exhibits type Ⅱ band structure alignment and intimate interface achieved through a magnesium(Mg)powder-assisted nitridation *** with widely reported heterologous heterostructures,the as-obtained YTON_H homologous heterostructure could similarly exhibit enhanced charge separation as well as photocatalytic water splitting performance with respect to its counterparts(YTaO_(4-x)N_(y)and YTaON_(2)).Meanwhile,detailed structural characterizations and spectroscopy analysis have been made to confirm the formation of heterostructure and promotion of spatial charge separation.

关键词： charge separation heterostructure oxynitride photocatalysis visible light

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Extended observer-based consensus tracking control for MASs with external disturbance and dynamic event-triggered strategy

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Science China Technological Sciences 2025年第3期68卷 232-242页

作者： Jian LIAO Kai MAO Bin XIN Jing HE Yaoqing ZHANG Jun CHENG Delin LUO Shaolei ZHOU college of physics and Electronic Information Gannan Normal University Shenzhen institute of Advanced Technology Chinese Academy of Sciences college of Basic Science Naval Aviation University School of Automation Beijing Institute of Technology School of Aerospace Engineering Xiamen University

This article explores the leader-following consensus tracking(LFCK) control issues of multi-agent systems(MASs)in the presence of external disturbances and general directed fixed communication topology. Its purpose is to enable all follower agents to achieve consensus tracking for the leader agent. Firstly, this article introduces an extended state observer for estimating each follower agent's unknown state and external disturbance. Subsequently, on the basis of the above-extended state observer and a dynamic event-triggered strategy, a distributed consensus tracking control protocol with disturbances restraint is developed,which can reduce the MAS's update frequency on the premise of ensuring the control protocol's effectiveness. Furthermore,the MAS's stability and the absence of Zeno behavior are analyzed and proved by the established Lyapunov functional and linear matrix inequality theory. Finally, the validity and feasibility of the proposed approach are validated through a group of comparative numerical simulation experiments.

关键词： leader-following consensus tracking (LFCK) dynamic event-triggered strategy external disturbances state observer multi-agent systems

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Investigations of liquid-liquid transitions in metallic melts by fast differential scanning calorimetry

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Science China(physics,Mechanics & Astronomy) 2025年

作者： Qi Cheng Yonghao Sun Weihua Wang Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Peking University School of physics and Electronic Information Anhui Normal University institute of physics Chinese Academy of Sciences Songshan Lake Materials Lab

Liquid-liquid transition in metallic melts is an intriguing phenomenon often confused with liquid-liquid separation, oxidation or precipitation. Here, we employ a state-of-the-art ultrafast chip-based differential scanning calorimeter to investigate the thermal behavior of six metallic melts, ranging from unary to quinary systems, at temperatures above their liquidus. Calorimetric signals of liquid-liquid transition vary across systems: Sn melts showed no direct endothermic or exothermic events, though liquid-liquid transition influenced solidification and melting temperatures, while Yb-Zn melts exhibited an exothermic peak during cooling,indicating liquid-liquid transition. Thermal signals in other systems including Li, Pd-Ni-P, Yb-Mg-Zn-Cu and Au-Ag-Pd-Cu-Si,are primarily driven by compositional changes. Our in-situ analysis provides new insights into the structural and compositional evolution of metallic melts, offering significant implications for the design and processing of novel materials.

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Primordial black holes and scalar induced density perturbations: the effects of probability density functions

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Chinese physics C 2025年第02期 206-212页

作者：周敬之况宇庭常哲张旭坤朱庆华 Center for Joint Quantum Studies and Department of physics School of ScienceTianjin University institute of High Energy physics Chinese Academy of Sciences University of Chinese Academy of Sciences college of physics and Information Engineering Shanxi Normal University Department of physics and Chongqing Key Laboratory for Strongly Coupled physics Chongqing University

We investigate the second order energy density perturbation δ（2）induced by small-scale Gaussian and local-type non-Gaussian primordial curvature *** relative abundance of primordial black holes（PBHs） is calculated in terms of the probability density functions（PDFs） of the total energy density perturbation δr=δ（1）+1/2δ（2）.The effects of the second order density perturbation greatly reduce the upper bounds of small-scale power spectra of primordial curvature perturbations by one to two orders of *** a log-normal primordial power spectrum,its amplitude Aζis constrained to be approximately Aζ～3×10-3,and for the local-type non-Gaussianity with fNL=10,the upper bound of Aζis approximately 2.5×10-4.

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