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Latest cosmological constraints on Cardassian expansion models including the updated gamma-ray bursts

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Research in Astronomy and astrophysics 2011年第9期11卷 1019-1030页

作者： nan liang Pu-Xun Wu Zong-Hong Zhu department of Astronomy Beijing Normal University Beijing 100875 China center for High Energy physics Peking University Beijing 100871 China center of Nonlinear Science and department of physics Ningbo University Ningbo 315211 China

We constrain the Cardassian expansion models from the latest observa- tions, including the updated Gamma-ray bursts （GRBs）, which are calibrated using a cosmology independent method from the Union2 compilation of type Ia supernovae （SNe Ia）. By combining the GRB data with the joint observations from the Union2 SNe Ia set, along with the results from the Cosmic Microwave Background radia- tion observation from the seven-year Wilkinson Microwave Anisotropy Probe and the baryonic acoustic oscillation observation galaxy sample from the spectroscopic Sloan Digital Sky Survey Data Release. we find significant constraints on the model oarameters of the original Cardassian model ΩM0=0.282-0.014^0.015,n=0.03-0.05^＋0.05 and n=-0.16-3.26^＋0.25,β=0.76-0.58^＋0.34 of the modified polytropic Cardassian model, which are consistent with the ACDM model in a l-or confidence region. From the reconstruction of the deceleration parameter q（z） in Cardassian models, we obtain the transition redshift ZT = 0.73 ± 0.04 for the original Cardassian model and ZT = 0.68 ± 0.04 for the modified polytropic Cardassian model.

关键词： gamma-rays bursts -- cosmology cosmological parameters

Alloy strategy to synthesize Pt-early transition metal oxide interfacial catalysts

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nano Research 2024年第4期17卷 3390-3397页

作者： Shi-Long Xu Hang nan Wanqun Zhang Yue Lin Sheng-Qi Chu Hai-Wei liang Hefei National Research center for Physical Sciences at the Microscale Department of ChemistryUniversity of Science and Technology of ChinaHefei 230026China School of Materials and Chemical Engineering Anhui Jianzhu UniversityHefei 230601China Institute of High Energy physics Chinese Academy of SciencesBeijing 100049China

Metal oxide supported metal catalysts show promising catalytic performance in many industry-relevant ***,the enhancement of performance is often limited by the insufficient metal/metal oxide *** this work,we demonstrate a general synthesis of Pt-early transition metal oxide(Pt-MO_(x),M=Ti,Zr,V,and Y)catalysts with rich interfacial sites,which is based on the air-induced surface segregation and oxidation of M in the supported Pt-M alloy *** characterizations verify the dynamic structural response of Pt-M alloy catalysts to air and the formation of Pt-MO_(x) catalysts with abundant interfacial *** prepared Pt-TiO_(x) interfacial catalysts exhibit improved performance in hydrogenation reactions of benzaldehyde,nitrobenzene,styrene,and furfural,as a result of the heterolytic dissociation of H_(2) at Pt-metal oxide interfacial sites.

关键词： Pt-early transition metal oxide interfacial catalyst alloy oxidation strategy interfacial sites hydrogenation reactions heterolytic dissociation

Spin Evolution of the Magnetar SGR J1935+2154

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Research in Astronomy and astrophysics 2024年第1期24卷 201-211页

作者： Ming-Yu Ge Yuan-Pei Yang Fang-Jun Lu Shi-Qi Zhou Long Ji Shuang-nan Zhang Bing Zhang liang Zhang Pei wang Kejia Lee Weiwei Zhu Jian Li Xian Hou Qiao-Chu Li Key Laboratory of Particle astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China South-Western Institute For Astronomy Research Yunnan UniversityKunming 650504China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China Key Laboratory of Stellar and Interstellar physics and School of physics and Optoelectronics Xiangtan UniversityXiangtan 411105China School of physics and Astronomy Sun Yat-Sen UniversityZhuhai 519082China university of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China Nevada center for astrophysics University of NevadaLas VegasNV 89154USA department of physics and Astronomy University of NevadaLas VegasNV 89154USA National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China department of Astronomy Peking UniversityBeijing 100871China CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China Yunnan Observatories Chinese Academy of SciencesKunming 650216China School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key laboratory of Modern Astronomy and astrophysics Nanjing UniversityNanjing 210023China

Fast radio bursts(FRBs)are short pulses observed in radio frequencies usually originating from cosmological *** discovery of FRB 200428 and its X-ray counterpart from the Galactic magnetar SGR J1935+2154suggests that at least some FRBs can be generated by ***,the majority of X-ray bursts from magnetars are not associated with radio *** fact that only in rare cases can an FRB be generated raises the question regarding the special triggering mechanism of *** we report long time spin evolution of SGR J1935+2154 until the end of *** to v and v,the spin evolution of SGR J1935+2154 could be divided into two *** first stage evolves relatively steady evolution until 2020 April *** the burst activity in2020,the spin of SGR J1935+2154 shows strong variations,especially for *** the burst activity in 2022October,a new spin-down glitch with△v/v=(-7.2±0.6)×10^(-6)is detected around MJD 59876,which is the second event in SGR J1935+*** the end,spin frequency and pulse profile do not show variations around the time of FRB 200428 and radio bursts 221014 and 221021,which supply strong clues to constrain the trigger mechanism of FRBs or radio bursts.

关键词： (stars:)pulsars:general (stars:)pulsars:individual(SGR J1935+2154) X-rays:bursts

Testing the distance-duality relation with a combination of cosmological distance observations

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Research in Astronomy and astrophysics 2011年第10期11卷 1199-1208页

作者： Shuo Cao nan liang department of Astronomy Beijing Normal University Beijing 100875 China center for High Energy physics Peking University Beijing 100871 China

We propose an accurate test of the distance-duality （DD） relation, η = DL（z）（1 ＋ z）^-2/DA（z） = 1 （where DL and DA are the luminosity distances and angular diameter distances, respectively）, with a combination of cosmological observational data of Type Ia Supernovae （SNe Ia） from the Union2 set and the galaxy cluster sample under an assumption of the spherical model. In order to avoid bias brought on by redshift non-coincidence between observational data and to consider redshift error bars of both clusters and SNe Ia in the analysis, we carefully choose the SNe Ia points which have the minimum acceptable redshift difference of the galaxy cluster sample （│△Z│min = σz,SN ＋σz,cluster）. By assuming η to be a constant and defined as functions of the redshift parameterized by six different expressions, we find that there exists no observable evidence for variations in the DD relation based on the collected data, since related statistical tests are well satisfied within the 1σ confidence level for most cases. Further, considering different values of △z as constraints, we also find that the choice of △z may play an important role in this model-independent test of the DD relation for the spherical sample of galaxy clusters.

关键词： distance scale -- galaxies clusters general -- supernovae general

The In-Flight Realtime Trigger and Localization Software of GECAM

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Research in Astronomy and astrophysics 2024年第10期24卷 11-24页

作者： Xiao-Yun Zhao Shao-Lin Xiong Xiang-Yang Wen Xin-Qiao Li Ce Cai Shuo Xiao Qi Luo Wen-Xi Peng Dong-Ya Guo Zheng-Hua An Ke Gong Jin-Yuan Liao Yan-Qiu Zhang Yue Huang Lu Li Xing Wen Fei Zhang Jing Duan Chen-Wei wang Dong-Li Shi Peng Zhang Qi-Bin Yi Chao-Yang Li Yan-Bing Xu Xiao-Hua liang Ya-Qing Liu Da-Li Zhang Xi-Lei Sun Fan Zhang Gang Chen Huan-Yu wang Sheng Yang Xiao-Jing Liu Min Gao Mao-Shun Li Jin-Zhou wang Xing Zhou Yi Zhao wang-Chen Xue Chao Zheng Jia-Cong Liu Xing-Bo Han Jin-Ling Qi Jia Huang Ke-Ke Zhang Can Chen Xiong-Tao Yang Dong-Jie Hou Yu-Sa wang Rui Qiao Xiang Ma Xiao-Bo Li Ping wang Xin-Ying Song Li-Ming Song Shi-Jie Zheng Bing Li Hong-Mei Zhang Yue Zhu Wei Chen Jian-Jian He Zhen Zhang Jin Hou Hong-Jun wang Yan-Chao Hao Xiang-Yu wang Zong-Yuan Yang Zhi-Long Wen Zhi Chang Yuan-Yuan Du Rui Gao Xiao-Fei Lan Yan-Guo Li Gang Li Xu-Fang Li Fang-Jun Lu Hong Lu Bin Meng Feng Shi Hui wang Hui-Zhen wang Yu-Peng Xu Jia-Wei Yang Xue-Juan Yang Shuang-nan Zhang Chao-Yue Zhang Cheng-Mo Zhang Zhi-Cheng Tang Cheng Cheng Key Laboratory of Particle astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China university of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China School of Information Science and Technology Southwest Jiaotong UniversityChengdu 611756China Key Laboratory of Stellar and Interstellar physics and department of physics Xiangtan UniversityXiangtan 411105China physics and Space Science College China West Normal UniversityNanchong 637002China department of Astronomy Beijing Normal UniversityBeijing 100875China Innovation Academy for Microsatellites of CAS Shanghai 201203China Changchun university of Science and Technology Changchun 130022China Chinese Academy of Sciences South America center for Astronomy National Astronomical ObservatoriesCASBeijing 100101China

Realtime trigger and localization of bursts are the key functions of GECAM,an all-sky gamma-ray monitor launched on 2020 December *** developed a multifunctional trigger and localization software operating in the CPU of the GECAM Electronic *** onboard software has the following features:high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation,dedicated localization algorithm optimized for both short and long bursts,and low time latency of the trigger information which is downlinked through the Global Short Message Communication service of the global BeiDou navigation *** paper provides a detailed description of the design and development of the trigger and localization software system for *** covers the general design,workflow,the main functions,and the algorithms used in the *** paper also includes on-ground trigger tests using simulated gamma-ray bursts generated by a dedicated X-ray tube,as well as an overview of the performance for real celestial bursts during its in-orbit operation.

关键词： telescopes instrumentation:detectors methods:observational

Graph deep learning accelerated efficient crystal structure search and feature extraction

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npj Computational Materials 2023年第1期9卷 524-532页

作者： Chuan-nan Li Han-Pu liang Xie Zhang Zijing Lin Su-Huai Wei department of physics University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China beijing Computational Science Research center Beijing 100193China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China

Structural search and feature extraction are a central subject in modern materials design,the efficiency of which is currently limited,but can be potentially boosted by machine learning(ML).Here,we develop an ML-based prediction-analysis framework,which includes a symmetry-based combinatorial crystal optimization program(SCCOP)and a feature additive attribution model,to significantly reduce computational costs and to extract property-related structural *** method is highly accurate and predictive,and extracts structural features from desired structures to guide materials *** first test SCCOP on 35 typical compounds to demonstrate its *** a case study,we apply our approach to a two-dimensional B-C-N system,which identifies 28 previously undiscovered stable structures out of 82 compositions;our analysis further establishes the structural features that contribute most to energy and *** to conventional approaches,SCCOP is about 10 times faster while maintaining a comparable *** framework is generally applicable to all types of systems for precise and efficient structural search,providing insights into the relationship between ML-extracted structural features and physical properties.

关键词： structural crystal precise

Electric-field control of topological spin textures in BiFe_(O3)/La_(0.67)Sr_(0.33)MnO_(3)heterostructure at room temperature

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Rare Metals 2023年第2期42卷 399-405页

作者： Ai-Ji wang liang Yang Jian Ge Gong-Xun Deng Yu-Ben Yang Jing-Di Lu Yue-Lin Zhang Yin-Shu wang Hai-Ming Yu Ling-Fei wang Ce-Wen nan Jin-Xing Zhang department of physics Beijing Normal UniversityBeijing100875China Hefei National Research center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei230026China Fert beijing Institute MIIT Key Laboratory of SpintronicsSchool of Integrated Circuit Science and EngineeringBeihang UniversityBeijing100191China State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Electric-field control of topological magnetic states in thinfilm heterostructures is promising for applications in nextgeneration memory or logic devices with ultrahigh density and low-power *** materials,where spin and polar degrees of freedom coexist,provide a versatile playground to manipulate magnetism(converse magnetoelectric effect).Here,we report that the topological spin textures can be controlled by electric field in rhombohedral BiFeO_(3)/monoclinic La_(0.67)Sr_(0.33)MnO_(3)thin-film heterostructure at room temperature.

关键词： temperature textures field

Shear banding-inducedslip enables unprecedented strength-ductility combination of laminated metallic composites

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Journal of Materials Science & Technology 2022年第15期110卷 260-268页

作者： Shuang Jiang Ru Lin Peng Kristián Máthis Hai-Le Yan Gergely Farkas Zoltán Hegedues Ulrich Lienert Johan Moverare Xiang Zhao liang Zuo nan Jia Yan-Dong wang Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang 110819China Division of Engineering Materials Department of Management and EngineeringLinköping UniversityLinköping 58183Sweden department of physics of Materials Faculty of Mathematics and PhysicsCharles UniversityKe Karlovu 5Prague 12116Czech Republic Nuclear physics Institute of the Czech Academy of Sciences Rež130Husinec-ˇRež25068Czech Republic Deutsches Elektronen-Synchrotron(DESY) Notkestr.85Hamburg 22607Germany beijing Advanced Innovation center for Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083China

Shear bands in metallic materials have been reported to be catastrophic because they normally lead to non-uniform plastic deformation. Ductility of laminated metallic composites deteriorates with increasing processing strain, particularly for those having hexagonal-close-packed(hcp) constituents due to inadequate slip systems and consequently prominent shear banding. Here, we propose a design strategy that counterintuitively tolerates the bands with localized strains, i.e. the shear banded laminar(SBL) structure, which promotes dislocation activation in hcp metals and renders unprecedented strengthductility combination in hcp-metal-based composites fabricated by accumulative roll bonding(ARB). The SBL structure is characterized with one soft hcp metal constrained by adjacent hard metal in which dislocations have been accumulated near the bimetal interfaces. High-energy X-ray diffraction astonishingly reveals that more than 90% of dislocations are non-basal in Ti layers of the SBL Ti/Nb composite processed by eight ARB cycles. Moreover, dislocations occupy a high fraction of ~30%, promoting further cross slip. The unique stress field tailored by both shear banding and heterophase interface-mediated deformation accommodation triggers important slip. This SBL design is of significance for developing hcp-based laminates and other heterostructured materials with high performances.

关键词： Shear band Laminated metallic composites Ductility High-energy X-ray diffraction Dislocation slip

Determining the contribution of Mo single atoms components in MoO_(2)nanocatalyst in transfer hydrogenation

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nano Research 2023年第2期16卷 2302-2310页

作者： Ze-nan Hu Yongjian Ai Yan Zhao Yiming wang Kelong Ding Wenhui Zhang Rongxiu Guo Xinyue Zhang Xiangbin Cai Ning wang Jianshe Hu Qionglin liang Hongyang Liu Fei Huang Limin Wu Jiangwei Zhang Hong-bin Sun School of Environmental Engineering and Chemistry Luoyang Institute of Science and TechnologyLuoyang 471023China department of Chemistry Northeastern UniversityShenyang 110819China MOE Key Laboratory of Bioorganic Phosphorus Chemistry&Chemical Biology Beijing Key Lab of Microanalytical Methods&InstrumentationDepartment of ChemistryCenter for Synthetic and Systems BiologyTsinghua UniversityBeijing 100084China College of Energy Material and Chemistry Inner Mongolia UniversityHohhot 010021China department of physics and center for Quantum Materials Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong SARChina Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

nanocatalysts are likely to contain undetected single-atom components,which may have been ignored but have significant effect in catalytic ***,we report a catalyst composed of Mo single atoms(SAs)and MoO_(2)nanoparticles(NPs)(MoSAs-MoO_(2)@NC),which is an exact model to understand how the SAs contribute to the *** experimental results and the density functional theory calculations reveal that Mo SAs on nitrogen-doped carbon provides the reaction zone for nitro reduction,while MoO_(2)is the active site for decomposing hydrazine hydrate to produce H*.Thanks to the synergy between Mo SAs and MoO_(2)NPs,this catalyst exhibits noble metal-like catalytic activity(100%conversion at 4 min)for the dechlorination-proof transfer ***,the hydrogen migration on the catalyst is verified by the electrochemical tests in the absence of a hydrogen *** work provides a model for further study on the coexistence of single atoms in nanoparticle catalysts.

关键词： synergistic effect Mo single atoms MoO_(2)nanocatalyst transfer hydrogenation nitroarenes