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Fast efficient photon deceleration in plasmas by using two laser pulses at different frequencies

matter and Radiation at Extremes 2024年第3期9卷 11-18页

作者： Y.x.wang x.L.Zhu S.m.Weng P.Li x.F.Li H.Ai H.R.Pan Z.m.Sheng Key Laboratory for Laser Plasmas(moe) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA Shanghai Jiao Tong UniversityShanghai 200240China Research Center of Laser Fusion of China Academy of Engineering Physics MianyangSichuan 621900China State key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Tsung-dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

The generation of ultrashort high-power light sources in the mid-infrared(mid-IR)to terahertz(THz)range is of interest for applications in a number of fields,from fundamental research to biology and medicine.Besides conventional laser technology,photon deceleration in plasma wakes provides an alternative approach to the generation of ultrashort mid-IR or THz pulses.Here,we present a photon deceleration scheme for the efficient generation of ultrashort mid-IR or THz pulses by using an intense driver laser pulse with a relatively short wavelength and a signal laser pulse with a relatively long wavelength.The signal pulse trails the driver pulse with an appropriate time delay such that it sits at the front of the second wake bubble that is driven by the driver pulse.Owing to its relatively long wavelength,the signal pulse will be subjected to a large gradient of the refractive index in the plasma wake bubble.Consequently,the photon deceleration in the plasma wake becomes faster and more efficient for signal pulses with longer wavelengths.This greatly enhances the capacity and efficiency of photon deceleration in the generation of ultrashort high-power light sources in the long-wavelength IR and THz spectral ranges.

关键词： laser ultrashort photon

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Processing, microstructure and mechanical Properties of Ti6Al4V Particles-Reinforced mg matrix Composites

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Acta metallurgica Sinica(English Letters) 2016年第10期29卷 940-950页

作者： x.m.wang x.J.wang x.S.Hu K.Wu m.Y.Zheng School of materials Science and Engineering Harbin Institute of Technology

Novel Ti6Al4V particles-reinforced AZ91 mg matrix composites were successfully fabricated by stir casting method. The stirring time in semisolid condition directly affected the particle distribution and the quality of the ingots. Furthermore, the optimal speed of the heating and the liquid stirring could overcome particle settlement caused by the density difference between the matrix and the particles. Ti6Al4V particles distributed uniformly in the composites with different particle contents. The average grain size decreased with the increase in the particle contents. The Ti6A14V particles bonded pretty well with the alloy matrix. In addition, there were some interfacial reactions in the composites. There were rod-like A13Ti phases at the interface. The precipitates extended from the particle surface to the matrix, and they might improve the interfacial bonding strength. The ultimate tensile strength, yield strength and elastic modulus were enhanced as the particle contents increased, and the elongation was much better than that of the same matrix material reinforced with SiC particles. Thus, the novel composites exhibit better comprehensive mechanical properties.

关键词： magnesium matrix composites Ti6Al4V particles Stir casting microstructure mechanicalproperties

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machine learning guided automatic recognition of crystal boundaries in bainitic/martensitic alloy and relationship between boundary types and ductile-to-brittle transition behavior

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Journal of materials Science & Technology 2021年第25期84卷 49-58页

作者： x.C.Li J.x.Zhao J.H.Cong R.D.K.misra x.m.wang x.L.wang C.J.Shang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Department of metallurgical Materials and Biomedical EngineeringUniversity of Texas at El Paso500 W.University AvenueEl PasoTX 79968USA

Gradient boosting decision tree(GBDT)machine learning(mL)method was adopted for the first time to automatically recognize and conduct quantitative statistical analysis of boundaries in bainitic microstructure using electron back-scatter diffraction(EBSD)data.In spite of lack of large sets of EBSD data,we were successful in achieving the desired accuracy and accomplishing the objective of recognizing the boundaries.Compared with a low model accuracy ofxis-angle pair as characteristic features,the accuracy of the model was significantly enhanced to about 88%when the Euler angle was converted to overall misorientation angle(OmA)and specific misorientation angle(SmA)and considered as important features.In this model,the recall score of prior austenite grain(PAG)boundary was~93%,high angle packet boundary(OmA>40°)was~97%,and block boundary was~96%.The derived outcomes of mL were used to obtain insights into the ductile-to-brittle transition(DBTT)behavior.Interestingly,mL modeling approach suggested that DBTT was not determined by the density of high angle grain boundaries,but significantly influenced by the density of PAG and packet boundaries.The study underscores that mL has a great potential in detailed recognition of complex multi-hierarchical microstructure such as bainite and martensite and relates to material performance.

关键词： machine learning Feature engineering Automatic recognition Lath structure Crystallography

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12.6μm-Thick Asymmetric Composite Electrolyte with Superior Interfacial Stability for Solid-State Lithium-metal Batteries

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Nano-micro Letters 2024年第9期16卷 397-409页

作者： Zheng Zhang Jingren Gou Kaixuan Cui xin Zhang Yujian Yao Suqing wang Haihui wang Beijing Key Laboratory for membrane materials and Engineering Department of Chemical EngineeringTsinghua UniversityBeijing 100084People’s Republic of China School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510000People’s Republic of China

Solid-state lithium metal batteries(SSLmBs)show great promise in terms of high-energy-density and high-safety performance.However,there is an urgent need to address the compatibility of electrolytes with high-voltage cathodes/Li anodes,and to minimize the electrolyte thickness to achieve highenergy-density of SSLmBs.Herein,we develop an ultrathin(12.6μm)asymmetric composite solid-state electrolyte with ultralight areal density(1.69 mg cm^(−2))for SSLmBs.The electrolyte combining a garnet(LLZO)layer and a metal organic framework(mOF)layer,which are fabricated on both sides of the polyethylene(PE)separator separately by tape casting.The PE separator endows the electrolyte with flexibility and excellent mechanical properties.The LLZO layer on the cathode side ensures high chemical stability at high voltage.The mOF layer on the anode side achieves a stable electric field and uniform Li flux,thus promoting uniform Li^(+)deposition.Thanks to the well-designed structure,the Li symmetric battery exhibits an ultralong cycle life(5000 h),and high-voltage SSLmBs achieve stable cycle performance.The assembled pouch cells provided a gravimetric/volume energy density of 344.0 Wh kg^(−1)/773.1 Wh L^(−1).This simple operation allows for large-scale preparation,and the design concept of ultrathin asymmetric structure also reveals the future development direction of SSLmBs.

关键词： Solid-state lithium metal batteries Composite solid-state electrolyte Ultrathin asymmetric structure Pouch cells

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High-responsivity on-chip waveguide coupled germanium photodetector for 2 μm waveband

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Photonics Research 2024年第1期12卷 115-122页

作者： JIANING wang xI wang YIHANG LI YANFU YANG QINGHAI SONG KE xU Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic materials and Intelligent Photonic Systems Harbin Institute of TechnologyShenzhen 518055China Department of Electronic&Information Engineering Harbin Institute of TechnologyShenzhen 518055China Department of Science Harbin Institute of TechnologyShenzhen 518055China

Recently,the emerging 2μm waveband has gained increasing interest due to its great potential for a wide scope of applications.Compared with the existing optical communication windows at shorter wavelengths,it also offers distinct advantages of lower nonlinear absorption,better fabrication tolerance,and larger free carrier plasma effects for silicon photonics,which has been a proven device technology.While much progress has been witnessed for silicon photonics at the 2μm waveband,the primary challenge still exists for on-chip detectors.Despite the maturity and compatibility of the waveguide coupled photodetectors made of germanium,the 2μm regime is far beyond its cutoff wavelength.In this work,we demonstrate an efficient and high-speed on-chip waveguidecoupled germanium photodetector operating at the 2μm waveband.The weak sub-bandgap absorption of epitaxial germanium is greatly enhanced by a lateral separation absorption charge multiplication structure.The detector is fabricated by the standard process offered by a commercial foundry.The device has a benchmark performance with responsivity of 1.05 A/W and 3 dB bandwidth of 7.12 GHz,which is able to receive high-speed signals with up to 20 Gbit/s data rate.The availability of such an efficient and fast on-chip detector circumvents the barriers between silicon photonic integrated circuits and the potential applications at the 2μm waveband.

关键词： waveguide responsivity wave

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Grain refinement of mg-Ca alloys by native mgO particles

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Journal of magnesium and Alloys 2024年第3期12卷 980-996页

作者： Shihao wang Yun wang Quentin m.Ramasse Zhongyun Fan Super STEm Laboratory SciTech Daresbury CampusDaresbury WA44ADUK School of Chemical and Process Engineering University of LeedsLeeds LS29JTUK BCAST Brunel University LondonUxbridgeMiddlesex UB83PHUK

In mg-Ca alloys the grain refining mechanism,in particular regarding the role of nucleant substrates,remains the object of debates.Although native mgO is being recognised as a nucleating substrate accounting for grain refinement of mg alloys,the possible interactions of mgO with alloying elements that may alter the nucleation potency have not been elucidated yet.Herein,we design casting experiments of mg-xCa alloys varied qualitatively in number density of native mgO,which are then comprehensively studied by advanced electron microscopy.The results show that grain refinement is enhanced as the particle number density of mgO increases.The native mgO particles are modified by interfacial layers due to the co-segregation of Ca and N solute atoms at the mgO/mg interface.Using aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy,we reveal the nature of these Ca/N interfacial layers at the atomic scale.Irrespective of the crystallographic termination of mgO,Ca and N co-segregate at the mgO/mg interface and occupy mg and O sites,respectively,forming an interfacial structure of a few atomic layers.The interfacial structure is slightly expanded,less ordered and defective compared to the mgO matrix due to compositional deviations,whereby the mgO substrate is altered as a poorer template to nucleate mg solid.Upon solidification in a TP-1 mould,the impotent mgO particles account for the grain refining mechanism,where they are suggested to participate into nucleation and grain initiation processes in an explosive manner.This work not only reveals the atomic engineering of a substrate through interfacial segregation but also demonstrates the effectiveness of a strategy whereby native mgO particles can be harnessed for grain refinement in mg-Ca alloys.

关键词： mg-Ca alloy Grain refinement mgO Interfacial segregation STEm/EELS Solidification.

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Stress triggering effect on the 2022 Honghe m_(S)5.0 earthquake with historical strong earthquakes

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Geodesy and Geodynamics 2024年第2期15卷 107-113页

作者： mingce wang Zifeng Liu Ruijie Luo Yunnan Earthquake Agency Kunming 650224China School of Earth Sciences Yunnan UniversityKunming 650504China

The 2022 Honghe m_(S)5.0 seismic event is intriguing due to its occurrence in the south of the Red River Fault,an area historically lacking seismic activities greater than m_(S)5.0.To elucidate the seismogenic mechanism and scrutinize stress-triggered interactions,we calculated co-seismic and post-seismic Coulomb stress alterations induced by nine historical seismic events(m≥6.0).The analysis reveals that these substantial seismic events provoked co-seismic stress augmentations of 1.409 bar and postseismic stress increments of 0.159 bar.Noteworthy seismic events,such as the 1833 Songming,1877Shiping,1913 Eshan,and 1970 Tonghai earthquakes,catalyzed the occurrence of the Honghe earthquake.Areas of heightened future seismic risk include the southern region of the Red River Fault and the eastern segments of the Shiping-Jianshui and Qujiang faults.Additionally,we assessed the correlation between the spatial distribution of aftershocks and the Coulomb stress shift triggered by the mainshock,taking into account the influence of calculation parameter settings.

关键词： Honghe ms5.0 earthquake Coulomb failurestress Stress triggering Historical strongearthquakes

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Coseismic Coulomb stress changes induced by a 2020-2021 m_(W)>7.0 Alaska earthquake sequence in and around the Shumagin gap and its influence on the Alaska-Aleutian subduction interface

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Geodesy and Geodynamics 2024年第1期15卷 1-12页

作者： Lei Yang Jianjun wang Caijun xu School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Collaborative Innovation Center of Geospatial Technology Wuhan 430079China Key Laboratory of Geospace Environment and Geodesy Ministry of EducationWuhan UniversityWuhan 430079China

Three m_(W)>7.0 earthquakes in 2020-2021 occurred in the Shumagin seismic gap and its adjacent area of the Alaska-Aleutian subduction zone,including the mw7.8 Simeonof thrust earthquake on July 22,2020,the m_(W)7.6 Sand Point strike-slip earthquake on October 19,2020,and the m_(W)8.2 Chignik thrust earthquake on July 29,2021.The spatial and temporal proximity of these three earthquakes prompts us to probe stress-triggering effects among them.Here we examine the coseismic Coulomb stress change imparted by the three earthquakes and their influence on the subduction interface.Our results show that:(1)The Simeonof earthquake has strong loading effects on the subsequent Sand Point and Chignik earthquakes,with the Coulomb stress changes of 3.95 bars and 2.89 bars,respectively.The Coulomb stress change caused by the Sand Point earthquake at the hypocenter of the Chignik earthquake is merely around 0.01 bars,suggesting the negligible triggering effect on the latter earthquake;(2)The triggering effects of the Simeonof,Sand Point,and Chignik earthquakes on aftershocks within three months are not well pronounced because of the triggering rates of 38%,14%,and 43%respectively.Other factors may have played an important role in promoting the occurrence of these aftershocks,such as the roughness of the subduction interface,the complicated velocity structure of the lithosphere,and the heterogeneous prestress therein;(3)The three earthquakes caused remarkable coseismic Coulomb stress changes at the subduction interface nearby these mainshocks,with an average Coulomb stress change of 3.2 bars in the shallow region directly inwards the trench.

关键词： The 2020-2021 Alaska earthquake sequence Coseismic Coulomb stress change mainshock-aftershock triggering The Alaska-Aleutian subduction interface The Shumagin gap

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A Label-Free Deoxyribozyme Sensor for m^(6)A Demethylase Activity Detection

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Chinese Journal of Chemistry 2024年第9期42卷 951-956页

作者： xiuyuan wang Shusheng Yu Yuqiu He Fuan wang xiaoqing Liu College of Chemistry and molecular Sciences Wuhan UniversityWuhanHubei 430072China

A label-free deoxyribozyme(DNAzyme)biosensor for m^(6) demethylase activity detection is developed.When demethylase FTO(Fat mass and obesity-associated protein),an important m^(6) demethylase of ALKBH demethylase family is present,the m^(6) group is specifically demethylated,and the cleavage activity of DNAzyme is restored.This allows the cleavage product that contains G-quadruplex sequence to bind to thioflavin T(ThT)and generate fluorescence signals.The biosensor shows high specificity and sensitivity,and fast reaction speed.Our study demonstrates a new design of allosteric DNAzyme for sensing.This method represents the first label-free nucleic acid biosensor for FTO assay,providing a feasible route towards inhibitors screening.

关键词： DNAzyme Analytical methods Biosensing m^(6)A demethylation Fluorescence

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Advances of high-performance LiNi_(1-x-y)Co_(x)m_(y)O_(2) cathode materials and their precursor particles via co-precipitation process

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Particuology 2024年第3期86卷 67-85页

作者： Wenbiao Liang Yin Zhao Liyi Shi Zhuyi wang Yi wang meihong Zhang Shuai Yuan School of materials Science and Engineering Shanghai UniversityShanghai200444China Research Center of Nanoscience and Nanotechnology Shanghai UniversityShanghai200444China Emerging Industries Institute Shanghai UniversityJiaxingZhejiang314006China

Layered LiNi_(1-x-y)Co_(x)m_(y)O_(2)(m=mn or Al)is a promising cathode material for lithium-ion batteries due to its high specific capacity and acceptable manufacturing cost.However,the polycrystalline LiNi_(1-x-y)Co_(x)m_(y)O_(2) cathode material suffers from disordered orientation of primary particles and poor geometric symmetry of secondary particles,which severely hampers the migration of Lit ions.Furthermore,the resulting anisotropy accelerates the disintegration of the secondary particle structure,significantly affecting the electrochemical performance of the polycrystalline cathode.In spite of less grain boundary,the single-crystal LiNi_(1-x-y)Co_(x)m_(y)O_(2) cathodes still suffer from severe microcracks generated by repeated planar gliding during cycling,which poses a great challenge to the cycling stability of single-crystal materials.It's worth noting that the microstructure of the cathode material is mainly inherited from its precursor.Therefore,it is necessary to deeply understand the influence of the microstructure of Ni_(1-x-y)Co_(x)m_(y)(OH)2 on the electrochemical properties of LiNi_(1-x-y)Co_(x)m_(y)O_(2) cathode materials,so as to optimize the production process of preparing high-performance cathode precursors.In this review,we summarize recent advances in the research and development of Ni-rich cathode precursor materials.Firstly,the challenges faced by the Ni-rich hydroxide precursor materials are presented,including the effect of primary particle morphology and arrangement on the electrochemical performance of cathode materials,the influence of secondary particle morphology on lithium insertion reactions in cathode,and the effect of particle size on the microcracking of single-crystal particles.Secondly,the presentation of the conventional co-precipitation reactor,the mechanism of precursor particle growth,and the influence of coprecipitation parameters are described in detail.Finally,the strategies are systematically discussed to solve the challenges of hydroxide precursors,such as the inno

关键词： Lithium-ion batteries Cathode materials Co-precipitation Ni-rich layered oxides Single crystal Precursor particles

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