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Transport of ultraintense laser-driven relativistic electrons in dielectric targets

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high Power Laser Science and Engineering 2020年第1期8卷 7-15页

作者： X.h.Yang C.Ren h.xu Y.Y.Ma F.Q.Shao Department of Physics National University of Defense TechnologyChangsha 410073China Department of Mechanical Engineering University of RochesterNew York 14627USA IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityChangsha 410073China College of Computing Science National University of Defense TechnologyShanghai 200240China State Key Laboratory of NBC Protection for Civilian Beijing 102205China

Ultraintense laser-driven relativistic electrons provide a way of heating matter to high energy density states related to many applications. however, the transport of relativistic electrons in solid targets has not been understood well yet,especially in dielectric targets. We present the first detailed two-dimensional particle-in-cell simulations of relativistic electron transport in a silicon target by including the field ionization and collisional ionization processes. An ionization wave is found propagating in the insulator, with a velocity dependent on laser intensity and slower than the relativistic electron velocity. Widely spread electric fields in front of the sheath fields are observed due to the collective effect of free electrons and ions. The electric fields are much weaker than the threshold electric field of field ionization. Two-stream instability behind the ionization front arises for the cases with laser intensity greater than 5 × 1019W/cm^2 that produce high relativistic electron current densities.

关键词： ionization wave relativistic electrons transport ultraintense laser

Solidification pathway and phase transformation behavior in a beta-solidified gamma-TiAl based alloy

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Journal of Materials Science & Technology 2019年第11期35卷 2652-2657页

作者： h.xu X.B.Li W.W.Xing L.Shu Y.C.Ma K.Liu Institute of Metal Research Chinese Academy of SciencesShenyang 110016China MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology Engineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China

The phase transformation behavior of an as-cast Ti-42Al-5 Mn(at.%)alloy after subsequent quenching from 1380℃to 1000℃was investigated based on the differential thermal analysis(DTA),electron probe micro analyzer-backscattered electrons(EPMA-BSE),transmission electron microscope(TEM)and X-ray diffraction(XRD).The results show that,the solidification path can be summarized as follows:Liquid→Liquid+β→β→β→α→β+α+γ→βo+α2+γ→βo+γ+α2/γ→βo+γ+α2/γ+βo,sec,with the phase transformationα→βtemperature(Tβ)=1311℃,phase transformationγ→βtemperature of(Tγsolv)=1231℃,phase transformationα2→αorβo→βtemperature(Tα2→α/Tβo→β)=1168 C,eutectoid temperature(Teut)=1132℃and T(α2/γ→βo,sec)≈1120℃.In comparison with Ti-42 Al alloy,the Teut and Tγsolv are slightly increased while both the Tp is decreased obviously by 5%Mn *** quenched from the temperature of 1380-1260℃,the martensitic transformationβ→α'could occur to form the needlelike martensite structure inβ*** kind of martensitic structure is much obvious with the increase of temperature from 1260℃to 1380℃.When the temperature is below Tγsolv(1231℃),theγgrains would nucleate directly from theβ*** the temperature slightly lower than T(eut)(1132℃),the dottedβ(o,sec)phases could nucleate in the lamellar colonies besides theγlamellae precipitated withinα2 ***,at room-temperature(RT),the alloy exhibits(po+α2+γ)triple phase with microstructure ofβo+lamellae+γ,of which the lamellar structure consists ofα2,γandβo,sec *** phase transformation mechanisms in this alloy,involvingβ→α',β→γ,α2→α2/γandα2→βo,sec were discussed.

关键词： Titanium aluminides Quenching Phase transformation Microstructure βphase

Wafer-level SLID bonding for MEMS encapsulation

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Advances in Manufacturing 2013年第3期1卷 226-235页

作者： h.xu T.Suni V.Vuorinen J.Li h.heikkinen P.Monnoyer M.Paulasto-Krckel Department of Electronics School of Electrical EngineeringAalto University VTT Technical Research Centre of Finland

hermetic packaging is often an essential requirement to enable proper functionality throughout the device＇s lifetime and ensure the optimal performance of a micro electronic mechanical system （MEMS） device. Solid-liquid interdiffusion （SLID） bonding is a novel and attractive way to encapsulate MEMS devices at a wafer level. SLID bonding utilizes a low-melting-point metal to reduce the bonding process temperature; and metallic seal rings take out less of the valuable surface area and have a lower gas permeability compared to polymer or glass- based sealing materials. In addition, ductile metals can adopt mechanical and thermo-mechanical stresses during their service lifetime, which improves their reliability. In this study, the principles of Au-Sn and Cu-Sn SLID bonding are presented, which are meant to be used for wafer-level hermetic sealing of MEMS resonators. Seal rings in 15.24 cm silicon wafers were bonded at a width of 60 gin, electroplated, and used with Au-Sn and Cu-Sn layer structures. The wafer bonding temperature varied between 300 ℃ and 350 ℃, and the bonding force was 3.5 kN under the ambient pressure, that is, it was less than 0.1 Pa. A shear test was used to compare the mechanical properties of the interconnections between both material systems, in addition, important factors pertaining to bond ring design are discussed according to their effects on the failure mechanisms. The results show that the design ofmetal structures can significantly affect the reliability of bond rings.

关键词： (MEMS)bondingDefects Micro electronic mechanical systemSolid-liquid interdiffusion (SLID)Transient liquid-phase (TLP) bondingShear test Reliability

Phase diagrams of poiydisperse van der Waals fluids

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Phase diagrams of poiydisperse van der Waals fluids

A Dynamic Increamental hysteresis Model Incorporating Eddy Current Losses for Giant Magnetostrictive Materials

CCAST“液体物理和相关的问题”研讨会

作者： L.Bellier-Castella h.xu M.Baus Departement de Physique des Materiaur（UMR 5586 du CNRS）.Universite Claude Bernard-Lyonl.69622 Villeurbanne Cedex.France Departement de Physique des Materiaur（UMR 5586 du CNRS）.Universite Claude Bernard-Lyonl.69622 Villeurbanne Cedex.France Physique des Polymeres.Universile Libre de Bruxelles.Campus Plaine CP 223.B-1050 Brussels.Belgium

＜正＞The phase behavior of a system composed of spherical particles with a monomodal size distribution is investigated theoretically within the context of the van der Waals approximation for polydisperse fluids. It is shown how the binodals, spinodals, cloud-point and shadow curves as well as all the （polydispersity induced） critical points can be obtained for a variety of interaction potentials. The polydispersity induced modifications of the phase diagram （even for a polydispersity index / as small as I- 1.01） should be observable in some colloidal dispersions. （?） 2000 American Institute of Physics. [S0021 -9606（00）51842-X]

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A Dynamic Increamental Hysteresis Model Incorporating Eddy C...

Dissociation cross sections ofψ(3770),ψ(4040),ψ(4160),andψ(4415)mesons with nucleons

The 16th Annual Conference of hong Kong Society of Theoretical and Applied Mechanics 2012、The 1st Mainland-hong Kong Youth Forum on Mechanics 2012、The 8th Shanghai-hong Kong Forum on Mechanics and Its Application 2012

作者： Y.M.Pei h.xu D.N.Fang LTCS College of EngineeringPeking University

This paper addresses the deveolopment of a magneto-elastic coupling dynamic hysteresis model for giant magnetostrictive materials(GMMs).Firstly,a three-dimensional domain rotation mechanism is introduced to investigate how the magnetization and magnetostriction of GMMs change with stresses and applied magnetic *** eddy current effects are incorporated to predict the dynamic hystersis behaviour of *** study reveals that eddy current losses lead to increaseing magnetic hysteresis as the frequency *** model is validated by comparing the predicted results with experiment ***,the model is convenient to be used in engineering applications since the parameters referred to the model have definite physical meaning and can be easily determined by experiments.

关键词： Model A Dynamic Increamental hysteresis Model Incorporating Eddy Current Losses for Giant Magnetostrictive Materials

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Communications in Theoretical Physics 2024年第4期76卷 93-112页

作者： Ruo-Qing Ding Xiao-Ming xu h J Weber Department of Physics Shanghai UniversityBaoshanShanghai 200444China Department of Physics University of VirginiaCharlottesvilleVA 22904United States of America

We study the dissociation of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons in collision with nucleons, which takes place in high-energy proton-nucleus collisions. The quark interchange between a nucleon and a ■ meson leads to the dissociation of the ■ meson. We consider the reactions:■, and■, where R stands for ψ(3770), ψ(4040), ψ(4160), or ψ(4415). A reaction of a neutron and a ■ meson corresponds to a reaction of a proton and the ■ meson by replacing the up quark with the down quark and vice versa. Transition-amplitude formulas are derived from the S-matrix *** cross sections are calculated with the transition amplitudes for scattering in the prior form and in the post form. The cross sections relate to nodes in the radial wave functions of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons.

关键词： inelastic nucleon-charmonium scattering quark interchange relativistic constituent quark potential model

FAST Observations of an Extremely Active Episode of FRB 20201124A:Ⅰ.Burst Morphology

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Research in Astronomy and Astrophysics 2022年第12期22卷 54-69页

作者： D.J.Zhou J.L.han B.Zhang K.J.Lee W.W.Zhu D.Li W.C.Jing W.-Y.Wang Y.K.Zhang J.C.Jiang J.R Niu R Luo h.xu C.F.Zhang B.J.Wang J.W.xu P.Wang Z.L.Yang Y.Feng National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory of FAST NAOCChinese Academy of SciencesBeijing 100101China Department of Physics and Astronomy University of NevadaLas VegasNV 89154USA Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Department of Astronomy Peking UniversityBeijing 100871China CSIRO Space and Astronomy EppingNSW 1710Australia Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China

We report the properties of more than 600 bursts(including cluster-bursts)detected from the repeating fast radio burst(FRB)source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode on UTC 2021 September 25–28,in a series of four *** observations were carried out in the band of 1.0–1.5 Ghz by using the center beam of the L-band 19-beam *** monitored the source in sixteen1 hr sessions and one 3 hr session spanning 23 *** the bursts were detected during the first four *** this first paper of the series,we perform a detailed morphological study of 624 bursts using the two-dimensional frequencytime“waterfall”plots,with a burst(or cluster-burst)defined as an emission episode during which the adjacent emission peaks have a separation shorter than 400 *** duration of a burst is therefore always longer than 1 ms,with the longest up to more than 120 *** emission spectra of the sub-bursts are typically narrow within the observing band with a characteristic width of~277 *** center frequency distribution has a dominant peak at about 1091.9 Mhz and a secondary weak peak around 1327.9 *** bursts show a frequencydownwarddrifting *** on the drifting patterns,we classify the bursts into five main categories:downward drifting(263)bursts,upward drifting(3)bursts,complex(203),no drifting(35)bursts,and no evidence for drifting(121)*** are introduced based on the emission frequency range in the band(low,middle,high and wide)as well as the number of components in one burst(1,2,or multiple).We measured a varying scintillation bandwidth from about 0.5 Mhz at 1.0 Ghz to 1.4 Mhz at 1.5 Ghz with a spectral index of 3.0.

关键词： (stars:)pulsars:general Physical Data and Processes stars:individual(FRB 20201124A)

Aldehyde oxidase mediated enantioselective metabolic health risk of dinotefuran

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Science China Chemistry 2024年第6期67卷 2079-2091页

作者： Liwei xu Xinxin xu hua Kuang Chuanlai xu Xiaoling Wu State Key Laboratory of Food Science and Resources Jiangnan UniversityWuxi214122China International Joint Research Laboratory for Biointerface and Biodetection and School of Food Science and Technology Jiangnan UniversityWuxi214122China Collaborative Innovation center of Food Safety and Quality Control in Jiangsu Province Jiangnan UniversityWuxi214122China

Chiral pollutants often pose significant differential environmental health *** this study,the biotransformation of chiral dinotefuran(DIN)and its enantioselective metabolic toxicity mechanisms have been systemically ***,reversedphase chromatography-high resolution mass spectrometry was developed to quantify the content of DIN R/S chiral enantiomer with pg level sensitivity,revealing a lower elimination rate constant(K_(e))of S-DIN(0.730 h^(-1))than R-DIN(0.746 h^(-1)).Secondly,the interaction mechanism between DIN metabolism and important endogenous bioactive molecules,such as aldehyde oxidase(AOX)and neurotransmitters,was *** DIN nitro-group was converted into a guanidine group by the reducing site of nearby flavin adenine dinucleotide(FAD)in AOX with the preferred higher affinity of ***,the endogenous tryptophan(Trp)aldehyde metabolic intermediate,5-hydroxyindoleacetaldehyde(5-hIAL),provides a persistent electron donor for DIN reduction via the oxidation-catalyzed site in AOX,resulting in remarkable up-regulation of monoamine neurotransmitters such as serotonin and ***,the higher level of neurotransmitters further mediated dysregulation of oxylipin homeostasis via the serotonergic pathway,where S-DIN exhibited more pronounced liver lipid damage and environmental health risk with the accumulated lipid biomarkers,oxidized triglyceride(OxTG)and oxidized sphingomyelin(OxSM).This study elucidates the AOX-mediated enantioselectivity metabolic pathway of DIN,providing a new analytical method for chiral pollutants and paves the way for their health risk assessments.

关键词： neonicotinoid dinotefuran enantiomer aldehyde oxidase metabolomics health risk

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From 0D to 3D:hierarchical structured high-performance free-standing silicon anodes based on binder-induced topological network architecture

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Journal of Energy Chemistry 2024年第6期93卷 16-23,I0002页

作者： Yihong Tong Ruicheng Cao Guanghui xu Yifeng Xia hongyuan xu hong Jin hui xu Xi’an Jiaotong University Suzhou Academy Suzhou 215123JiangsuChina Nano Science and Technology Institute University of Science and Technology of ChinaSuzhou 215123JiangsuChina

Free-standing silicon anodes with high proportion of active materials have aroused great attention;however,the mechanical stability and electrochemical performance are severely ***,to resolve the appeal issues,a free-standing anode with a"corrugated paper"shape on micro-scale and a topological crosslinking network on the submicron and nano-scale is ***,an integrated three-dimensional electrode structure is constructed based on robust carbon nanotubes network with firmly anchored SiNPs via forming interlocking *** which,the hierarchical interlocking structure is achieved by directional induction of the binder,which ensures well integration during cycling so that significantly enhances mechanical stability as well as electronic and ionic conductivity of *** from it,this anode exhibits outsta nding performance under harsh service conditions including high Si loading,ultrahigh areal capacity(33.2 mA h cm^(-2)),and high/low temperatures(-15-60℃),which significantly extends its practical ***,the optimization mechanism of this electrode is explored to verify the crack-healing and structure-integration maintaining along cycling via a unique self-stabilization ***,from both the fundamental and engineering views,this strategy offers a promising path to produce high-performance free-standing electrodes for flexible device applications especially facing volume effect challenges.

关键词： Topological network Self-stabilization Flexibility Free-standing Silicon anode