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A New X-Ray tidal Disruption Event Candidate with Fast Variability

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Research in Astronomy and Astrophysics 2022年第5期22卷 28-35页

作者： j.hampel S.Komossa j.Greiner t.h.Reiprich M.Freyberg t.Erben Argelander-Institut für Astronomie Aufdem Hugel 71D-53121 BonnGermany Max-Planck Institut für Radioastronomie Auf dem Hugel 69D-53121 BonnGermany National Astronomical Observatories Chinese Academy of ScienceBeijing 100101China Max-Planck Institute für Extraterrestrische Physik GieBenbachstrasse 1D-85748 GarchingGermany

During a close encounter between a star and a supermassive black hole,the star can get disrupted by the black hole’s tidal forces,resulting in a tidal disruption event(tDE).the accretion of the star’s material onto the black hole produces strong emission in different wavelength *** we report the discovery with the Roentgen Satellite(ROSAt)of an X-ray-selected transient source in an optically non-active *** the location R.A.:13h31m57s.66 and decl.:-32°43’19".7 a sudden rise in X-ray luminosity by a factor of 8 within 8 days has been ***,a very soft X-ray spectrum with a blackbody temperature kt=0.1 keV and a peak luminosity of at least 1×10^(43)erg s^(-1)suggests a tDE interpretation,and the observed properties are very similar to previously identified soft X-ray(ROSAt)*** optical spectrum taken of the galaxy at the position of RXj133157.6324319.7 six years after the X-ray outburst does not show any emission lines as would be expected from a persistent active galactic *** redshift of the galaxy is determined to be 0.051 based on absorption *** is therefore likely a member of the galaxy cluster *** rise in X-ray luminosity happens within 8 days and thus appears to be fast for such an *** X-ray emission was detected 170 days before and 165 days after the event,and none was detected 25 yr later with the Neil Gehrels Swift *** change in X-ray luminosity is at least a factor of 40.

关键词： accretion-black holes-galaxies-tidal disruption-X-ray sources

基于深度学习的MRI影像组学无创识别hER2低表达状态可预测乳腺癌病人的无病生存期

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国际医学放射学杂志 2024年第2期 252-253页

作者： Y.Guo X.t.Xie W.j.tang S.Y.Chen M.Y.Wang Y.h.Fan 侯唯姝

摘要目的建立基于深度学习的MRI影像组学（DLR）特征模型，以预测人表皮生长因子受体2(hER2)低表达状态，并进一步通过DLR模型验证乳腺癌病人在预后方面的

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Enhanced helium ion irradiation tolerance in a Fe-Co-Ni-Cr-Al-ti high-entropy alloy with L12 nanoparticles

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journal of Materials Science & technology 2023年第12期143卷 169-177页

作者： Y.L.Zhao F.L.Meng t.Yang j.h.Luan S.F.Liu G.M.Yeli W.t.Lin W.h.Liu X.j.Liu C.t.Liu j.j.Kai School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China School of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Materials Science and Engineering Mechanical Behavior Division of Shenyang National Laboratory for Materials ScienceCity University of Hong KongHong KongChina Department of Mechanical Engineering City University of Hong KongHong KongChina Institute of Nuclear&New Energy technology Tsinghua UniversityBeijing 100084China

L12-strengthened high entropy alloys(hEAs)with excellent room and high-temperature mechanical prop-erties have been proposed as promising candidates as structural materials for advanced nuclear ***,knowledge about their radiation response is fairly *** the present work,a novel hEA with a high density of L12 nanoparticles was irradiated with he ion at 500°*** electron microscope(tEM)and atom probe tomography(APt)were employed to study the evolution of mi-crostructural stability and radiation-induced *** to the single-phase FeCoNiCr hEA,the main microstructural features were numerous large faulted dislocation loops and helium *** the irradiation resistance of the present L12-strengthened hEA is much improved in terms of reduced bubble size,which could be attributed to the considerable he trapping efficiency of the coherent pre-cipitate/matrix interface and the enhanced capability of the interface for damage elimination when the matrix channel width is *** analysis revealed that an inverse-Kirkendall-mechanism-dominated radiation-induced segregation(RIS)occurs around bubbles,where a significant Co enrichment and Ni de-pletion can be clearly *** addition,the competing dynamics of ballistic mixing and elemental clustering that raised from the irradiation-enhanced diffusion in a highly supersaturated matrix,along with the low precipitation nucleation barrier due to the small lattice misfit,lead to a dynamical pre-cipitation dissolution and re-precipitation appears under *** a promising phenomenon is expected to promote a potential self-healing effect and could in turn provide a sustainable irradiation tolerance over the operational lifetime of a reactor.

关键词： L12 nanoparticles high-entropy alloy helium bubble Phase stability Radiation-induced segregation

Association of daily sitting time and leisure-time physical activity with body fat among ***

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journal of Sport and health Science 2024年第2期13卷 195-203页

作者： jingwen Liao Min hu Kellie Imm Clifton j.holmes jie Zhu Chao Cao Lin Yang Guangdong Provincial Key Laboratory of Physical Activity and health Promotion Guangzhou Sport UniversityGuangzhou 510500China Scientific Research Center Guangzhou Sport UniversityGuangzhou 510500China Division of Epidemiology&Genetics Department of Population and Public Health SciencesKeck School of Medicine of the University of Southern CaliforniaLos AngelesCA 90033USA Program in Physical therapy Washington University School of MedicineSt.LouisMO 63110USA Center for human Nutrition Washington University School of MedicineSt.LouisMO 63110USA Department of Plastic and Reconstructive Surgery Shanghai East HospitalTongji UniversityShanghai 200070China Department of Cancer Epidemiology and Prevention Research Alberta Health ServicesCalgary T2S 3C3Canada Department of Oncology and Community health Sciences University of CalgaryCalgary T2N 1N4Canada

Background:Prolonged sitting and reduced physical activity lead to low energy ***,little is known about the joint impact of daily sitting time and physical activity on body fat *** investigated the independent and joint associations of daily sitting time and physical activity with body fat among ***:this was a cross-sectional analysis of *** representative data from the National health and Nutrition Examination Survey2011-2018 among adults aged 20 years or *** sitting time and leisure-time physical activity(LtPA)were self-reported using the Global Physical Activity *** fat(total and trunk fat percentage)was determined via dual X-ray ***:Among 10,808 adults,about 54.6%spent 6 h/day or more sitting;more than one-half reported no LtPA(inactive)or less than 150 min/week LtPA(insufficiently active)with only 43.3%reported 150 min/week or more LtPA(active)in the past *** fully adjusting for sociodemographic data,lifestyle behaviors,and chronic conditions,prolonged sitting time and low levels of LtPA were associated with higher total and trunk fat percentages in both *** stratifying by LtPA,the association between daily sitting time and body fat appeared to be stronger in those who were inactive/insuufficiently *** the joint analyses,inactive/insuufficiently active adults who reported sitting more than 8 h/day had the highest total(female:3.99%(95%confidence interval(95%CI):3.09%-4.88%);male:3.79%(95%CI:2.75%-4.82%))and trunk body fat percentages(female:4.21%(95%CI:3.09%-5.32%);male:4.07%(95%CI:2.95%-5.19%))when compared with those who were active and sitting less than 4 h/***:Prolonged daily sitting time was associated with increased body fat among *** higher body fat associated with 6 h/day sitting may not be offset by achieving recommended levels of physical activity.

关键词： Adults Body fat distribution Physical activity Sitting time

Role of grain boundary character on Bi segregation-induced embrittlement in ultrahigh-purity copper

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journal of Materials Science & technology 2023年第28期159卷 52-61页

作者： Y.X.hua K.X.Song h.t.Liu j.W.Wang C.M.Zhang Y.j.Zhou B.Pang j.t.Song j.L.he h.L.Zhao School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang 471023China henan Academy of Sciences Zhengzhou 450000China henan Key Laboratory of Advanced Conductor Materials Zhengzhou 450046China Provincial and Ministerial Co-construction of Collaborative Innovation Center of Nonferrous New Materials and Advanced Processing technology Luoyang 471023China Center of Electron Microscopy and State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China College of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

Bismuth(Bi),as an impurity element in copper and copper-based alloys,usually has a strong tendency of grain boundary(GB)segregation,which depends on the GB ***,the influence of such a segregation on the properties of ultrahigh-purity copper has been rarely reported and the exact structural arrangements of Bi atoms at different GBs remain largely *** this study,we investigated the influ-ence of trace amounts of Bi(50-300 wt ppm)on the ductility of an ultrahigh-purity copper(99.99999%)in the range of room temperature to 900°*** tensile results show that the addition of Bi seriously damages the ductility of the ultrahigh-purity copper at temperatures of 450-900°C,which is due to the GB segregation of *** this basis,such a segregation behavior at different types of GBs,including high and low angle GBs(hAGBs/LAGBs),and twin boundaries(tBs),via the scanning electron microscope-electron backscattered diffraction(SEM-EBSD)and aberration-corrected scanning transmission electron microscope(AC-StEM)investigations,combined with the first-principles calculations were systematically *** atomistic characterizations demonstrate an anisotropic Bi segregation,where severe enrich-ment of Bi atoms typically occurs at the hAGBs,while the absence of Bi adsorption prevails at LAGBs or *** particular,the segregated Bi at random hAGBs exhibited the directional bilayer adsorption,while the special symmetrical7 hAGB presented a unique Bi-rich cluster *** findings pro-vide a comprehensive experimental and computational understanding on the atomic-scale segregation of impurities in metallic materials.

关键词： Grain boundary character Embrittlement Bi segregation Atomic configuration Ultrahigh-purity copper

Deep convolutional Ritz method: parametric PDE surrogates without labeled data

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Applied Mathematics and Mechanics(English Edition) 2023年第7期44卷 1151-1174页

作者： j.N.FUhG A.KARMARKAR t.KADEEthUM h.YOON N.BOUKLAS Sibley School of Mechanical and Aerospace Engineering Cornell UniversityNew York 14853U.S.A Geomechanics Department Sandia National LaboratoriesAlbuquerque 87123U.S.A.

the parametric surrogate models for partial differential equations(PDEs)are a necessary component for many applications in computational sciences,and the convolutional neural networks(CNNs)have proven to be an excellent tool to generate these surrogates when parametric fields are *** are commonly trained on labeled data based on one-to-one sets of parameter-input and PDE-output ***,residual-based deep convolutional physics-informed neural network(DCPINN)solvers for parametric PDEs have been proposed to build surrogates without the need for labeled *** allow for the generation of surrogates without an expensive *** this work,we present an alternative formulation termed deep convolutional Ritz method(DCRM)as a parametric PDE *** approach is based on the minimization of energy functionals,which lowers the order of the differential operators compared to residualbased *** on studies involving the Poisson equation with a spatially parameterized source term and boundary conditions,we find that CNNs trained on labeled data outperform DCPINNs in convergence speed and generalization *** surrogates generated from the DCRM,however,converge significantly faster than their DCPINN counterparts,and prove to generalize faster and better than the surrogates obtained from both CNNs trained on labeled data and *** hints that the DCRM could make PDE solution surrogates trained without labeled data possibly.

关键词： physics-informed constraint physics-informed neural network(PINN) deep energy network convolutional neural network(CNN)

Analysis of the anelastic deformation of high-entropy Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) metallic glass under stress relaxation and recovery

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journal of Materials Science & technology 2022年第12期107卷 82-91页

作者： Y.j.Duan L.t.Zhang t.Wada h.Kato E.Pineda D.Crespo j.M.Pelletier j.C.Qiao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China Department of Physics Institute of Energy TechnologiesUniversitat Politècnica de CatalunyaBarcelona 08019Spain Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Universitéde Lyon MATEISUMR CNRS5510Bat.B.PascalINSA-LyonF-69621 Villeurbanne CedexFrance

the anelastic deformation behavior of Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass was probed by monitoring the stress relaxation and recovery processes. the stress relaxation under consecutive strain steps can be described by the Kohlrausch-Williams-Watts(KWW) function. In addition, considering a hierarchy of relaxation processes related to the structural heterogeneity, a constitutive model is proposed in order to describe the whole process of stress relaxation and determine the contribution of different time scales. Moreover, a crossover from stochastic activation to percolation of flow defects with the ultimate strain can be observed during stress relaxation process. the anelastic recovery process after a strain step is studied as a function of the initial strain level and characterized by means of a direct spectrum analysis. the peaks in the recovery time-spectra revealed the evolution of flow defects in Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass. the understanding of the atomic free-volume zones effect and the anelastic deformation provides important insight into how atomic structural features affect the deformation behavior of high-entropy metallic glasses, and may provide a new avenue into the improvement of their mechanical properties.

关键词： high-entropy metallic glass Stress relaxation Anelastic deformation Flow defects Free-volume zones

Achieving ultrahigh strength and ductility in high-entropy alloys via dual precipitation

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journal of Materials Science & technology 2023年第35期166卷 67-77页

作者： j.M.Guo B.C.Zhou S.Qiu h.j.Kong M.C.Niu j.h.Luan t.L.Zhang h.Wu Z.B.jiao Department of Mechanical Engineering Research Institute for Advanced ManufacturingThe Hong Kong Polytechnic UniversityHong KongChina the hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China Department of Materials Science and Engineering City University of Hong KongHong KongChina State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

the strength-ductility trade-offhas been a longstanding dilemma in metallic *** we report an innovative approach to achieve a high strength-ductility synergy via dual precipitation of sheared and bypassed precipitates.(Ni_(2) Co_(2) FeCr)_(96-x) Al_(4) Nb_(x)(at.%)alloys strengthened by nanoscale L12 particles and Laves precipitates were selected as a model for this study,and their precipitate microstructures and mechanical properties were thoroughly *** dual-precipitation-strengthened alloys exhibit a yield strength of more than 1400 MPa,an ultimate tensile strength of over 1800 MPa,and a uniform elon-gation of 18%,thus achieving a high strength-ductility *** analysis reveals that the nanoscale L1_(2) precipitates contribute to the strength via the particle shearing mechanism,whereas the Laves phase provides the strengthening through the Orowan bypass *** study of deformation microstruc-tures shows that the L1_(2) precipitates are sheared by stacking faults,which facilitates long-range disloca-tion gliding through the *** a result,deformation induces the formation of hierarchical stacking fault networks and immobile Lomer-Cottrell locks,which effectively enhance the work hardening ca-pability and plastic stability,thereby resulting in a high ductility at high strength *** are piled-up against the interface between the Laves precipitates and matrix,which increases the work hardening capability at the early stages of plastic deformation but causes stress *** dual precipitation strategy may be useful for many other alloys for achieving superior mechanical properties for technological applications.

关键词： high-entropy alloy Dual precipitation Precipitation strengthening Deformation mechanism

Structure evolution of the Fe_(3)C/Fe interface mediated by cementite decomposition in cold-deformed pearlitic steel wires

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journal of Materials Science & technology 2022年第6期101卷 28-36页

作者： Y.t.Zhou X.h.Shao S.j.Zheng X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control technology School of Materials Science and EngineeringHebei University of TechnologyTianjin 300130China

Cold-drawn pearlitic steel wire is irreplaceably used in industry owing to its outstanding mechanical property which is dominated by the cementite/ferrite(Fe_(3)C/Fe) interfaces in the material. however, the fine structures of the Fe3C/Fe interfaces in the deformed wires are less known to date. In this work, transmission electron microscopic investigation was performed on the atomic structures of the interfaces with the Isaichev orientation relationship(OR) in the wires with progressive deformation strains. In addition to the effect of the dislocation/interface interactions, this work revealed that the deformation-induced partial decomposition of cementite plays an important role in the interface reconstruction during deformation. the interfacial carbon vacancies generated by cementite decomposition and particularly, the amorphization of cementite layers in the sample with ε > 1 could effectively annihilated the interfacial dislocations and consequently relaxed the interfacial stress. the correlations between the interface structure changes and the mechanical properties of the wires were discussed.

关键词： Pearlitic steel Cementite decomposition Interface structure Deformation transmission electron microscopy