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Enhanced Grain Refining Effect of Mg–Zr Master Alloy on Magnesium Alloys via a Synergistic Strategy Involving Heterogeneous Nucleation and Solute‑Driven Growth Restriction

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1354-1366页

作者： Gang Zeng Hong liu Jing‑Peng Xiong jian‑long li Yong liu Key Laboratory of lightweight and High Strength Structural Materials of jiangxi Province School of Advanced ManufacturingNanchang UniversityNanchang 330031China

Zirconium(Zr)emerges as the most effective grain refiner for magnesium(Mg)alloys incorporating ***,Zr is introduced in the form of an Mg–Zr master ***,within Mg–Zr master alloys,Zr predominantly exists in a particle form,which tends to aggregate due to attractive van der Waals *** clustered Zr is prone to settling,thereby reducing its refining impact on Mg *** this work,a combined pretreatment process for Mg–Zr master alloys was proposed,encompassing the introduction of a physical field to intervene the agglomeration of particle Zr and the employ of high-temperature dissolution and peritectic reactions to promote the solid solution of *** results demonstrate that the particle Zr within the pretreated Mg–Zr master alloy is effectively dispersed and refined,and greater solute Zr levels can be *** subsequent grain refinement ability was studied on a typical Mg–6Zn–0.6Zr(wt%)*** outcome highlights that an improvement in the grain refinement efficacy(32.4%)of Mg–Zr master alloys was obtained with a holding time of 60 *** pretreated Mg–Zr master alloy significantly augments the efficiency of grain refinement for Mg alloys through a synergistic strategy involving heterogeneous nucleation and solute-driven growth *** crucial factor in achieving effective grain refinement of Zr in Mg alloys lies in regulating the presence and morphology of Zr in the Mg–Zr master alloy,distinguishing between particle Zr and solute *** study introduces a novel method for developing more efficient Mg–Zr refiners.

关键词： Magnesium alloy Mg-Zr master alloy Grain refinement Heterogeneous nucleation Solute-driven growth restriction Synergistic strategy

Robust time reversal processing for active detection of a small bottom target in a shallow water waveguide

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第5期11卷 401-406页

作者： Xiang PAN jian-long li Wen XU Xian-yi GONG Institute of lnformation and Communication Engineering Zhejiang University Hangzhou 310027 China Zhejiang Provincial Key Laboratory of Information Network Technology Hangzhou 310027 China

With the spatial-temporal focusing of acoustic energy,time reversal processing(TRP) shows the potential application for active target detection in shallow *** turn the ‘potential’ into a reality,the TRP based on a model source(MS) instead of a physical probe source(PS) is *** uncertain ocean environments,the robustness of TRP is discussed for the narrowband and broadband signal *** channel transfer function matrix is first constructed in the acoustic perturbation *** a steering vector for time reversal transmission is obtained by singular value decomposition(SVD) of the *** verification of the robust TRP,the tank experiments of time reversal transmission focusing and its application for active target detection are *** experimental results have shown that the robust TRP can effectively detect and locate a small bottom target.

关键词： Robustness Time reversal processing Bottom target detection Uncertain environment Sonar

Novel Synthesis of Sol-gel Derived Nanosized Mullite Powder

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Chinese Journal of Aeronautics 2006年第B12期19卷 71-73页

作者： liANG long li jian-bao liN Hong GUO Gang-feng HE Ming-sheng State Key Lab of New Ceramics and Fine Processing Dept of Materials Science and Engineering Tsinghua University Beijing 100084 China

Using hydrous aluminum chloride （AlCl3·6H2O） and silicon ethoxide （Si （OC2H5）4） as raw materials, a kind of nano-sized mullite powder was synthesized with the sol-gel process at the medium calcination temperature. The microstructures of the alumina-silica binary aerogel and calcined nano-sized materials were investigated by means of thermogravimetry-differential thermal analysis （TG-DTA）, scanning electron microscopy （SEM） and X-ray diffractometer （XRD）. The results show that the mullitization of Al2O3-SiO2 in gel starts from about 1 000℃ and its formation ofmullite takes place in the range of 1 100℃-1 250 ℃. The size of the nano-sized mullite powder calcined at 1 250 ℃ is measured to be about 30 nm.

关键词： mullite sol-gel synthesis temperature

Microstructure and texture evolution of Cu-Cr-Co-Ti alloys during the two-stage cryorolling

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Rare Metals 2024年第9期43卷 4535-4547页

作者： Jia-Jun Zhang long-jian li Zhi-Feng liu Zong-Ning Chen En-Yu Guo Hui-Jun Kang Ren-Geng li Tong-Min Wang Key Laboratory of Solidification Control and Digital Preparation Technology(liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Center of Hyper-Gravity Experimental and Interdisciplinary Research Zhejiang UniversityHangzhou 310058China Ningbo Institute of Dalian University of Technology Ningbo 315000China Key Laboratory for light-Weight Materials Nanjing Tech UniversityNanjing 210009China

This study entailed an investigation of the mechanical properties,microstructural and texture orientation evolutions of Cu-Cr-Co-Ti alloys prepared via twostage cryorolling and intermediate aging *** this end,X-ray diffraction and electron backscatter diffraction were *** results indicate that the two-stage cryorolling and intermediate aging treatments led to the development of profuse twin bundles and significantly enhanced the mechanical *** initial cryorolling led to coplanar slip and developed a strong Y({111})orientation,accelerating the formation of Goss({011})orientation and a Brass-type *** intermediate aging treatment relieved the restriction on dislocation slip and reoriented the grains toward the Copper({112})and Z({111})*** Z orientation,with a relatively high volume fraction,dominated the *** cryorolling intensified twinning and shear banding,transforming the Copper-type shear bands into Brass-type shear bands with rhomboidal prism *** areas inside the Brasstype shear bands exhibited a Y orientation,and the areas outside the shear bands exhibited a stable Brass-type *** evident decrease in the weighted Schmid factors demonstrated that the two-stage cryorolling and intermediate aging treatment can modify the texture evolution and aid the design of high-performance Cu alloys.

关键词： Copper alloys Two-stage cryorolling Macrotexture evolution Electron backscatter diffraction Schmid factor

C-reactive protein decreases interleukin-8 production in human endothelial progenitor cells by inhibition of p38 MAPK pathway

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Chinese Medical Journal 2009年第16期122卷 1922-1928页

作者： NAN Jing-long li jian-jun HE jian-guo Department of Cardiology Fu Wai Hospital Chinese Academy of Medical Sciences Peking Union Medical College Beijing 100037 China

Background C-reactive protein （CRP） has been reported to damage the vascular wall by inducing endothelial dysfunction and inflammation, and it is also speculated to have a role in attenuating angiogenic functions of human endothelial progenitor cells （EPCs）. Interleukin-8 （IL-8） is an important mediator of the paracrine mitogenic effect of EPCs which has direct angiogenic effects on mature endothelial cells. We, herein, investigated the direct effect of CRP on IL-8 production and gene expression in cultured human EPCs. Methods EPCs were isolated from the peripheral venous blood of healthy male volunteers. Cells were cultured in EndoCultTM liquid medium in the absence and presence of CRP at clinically relevant concentrations （5 to 25 μg/ml） for different durations （3 to 48 hours）. IL-8 protein and mRNA of cultured EPCs were evaluated using EliSA and real-time PCR. Results The results showed that CRP at a concentration of 10 μg/ml significantly reduced IL-8 secretion of cultured EPCs with a peak at 25 μg/ml, and also decreased mRNA expression in EPCs with a peak at 12 hours. In addition, preincubation of EPCs with SB203580, an inhibitor of p38 mitogen-activated protein kinase （MAPK） decreased CRP inhibition of IL-8 mRNA expression at 12 hours in EPCs. Conclusions Our study, for the first time, demonstrates that CRP directly inhibits EPCs IL-8 secretion, a key cytokine player of angiogenesis induced by EPCs. Inhibition occurred in part via an effect of CRP to active the p38 MAPK signal transduction pathway in EPC. The ability of CRP to inhibit EPCs IL-8 secretion may represent an important mechanism that further links inflammation to cardiovascular disease.

关键词： C-reactive protein endothelial progenitor cells interleukin-8

Generation of a curved plasma channel from a discharged capillary for intense laser guiding

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High Power Laser Science and Engineering 2023年第5期11卷 85-92页

作者： jian-long li Bo-Yuan li Xin-Zhe Zhu Ze-Wu Bi Xin-Hui Wen lin Lu Xiao-Hui Yuan Feng liu Min Chen Key Laboratory for Laser Plasmas(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghaiChina Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghaiChina Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghaiChina

Straight plasma channels are widely used to guide relativistic intense laser pulses over several Rayleigh lengths for laser wakefield ***,a curved plasma channel with gradually varied curvature was suggested to guide a fresh intense laser pulse and merge it into a straight channel for staged wakefield acceleration[***.120,154801(2018)].In this work,we report the generation of such a curved plasma channel from a discharged *** longitudinal and transverse density distributions of the plasma inside the channel were diagnosed by analyzing the discharging *** of the gas-filling mode,back pressure and discharging voltage on the plasma density distribution inside the specially designed capillary are *** show that a longitudinally uniform and transversely parabolic plasma channel with a maximum channel depth of 47.5µm and length of 3 cm can be produced,which is temporally stable enough for laser *** such a plasma channel,a laser pulse with duration of 30 fs has been successfully guided along the channel with the propagation direction bent by 10.4◦.

关键词： curved plasma channel discharging spectroscopy laser guiding

Influence of Material Properties on Analysis and Design of Pavements Using Shakedown Theory

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Journal of Shanghai Jiaotong University(Science) 2010年第3期15卷 329-333页

作者：孙阳沈水龙赵建立 School of Naval Architecture Ocean and Civil EngineeringShanghai Jiaotong University

Currently,traditional analysis and design methods are unreasonable in evaluating the performance and safety of *** characteristic of shakedown theory lends itself particularly to the analysis of *** on the lower bound shakedown theory,a simple and practical procedure for shakedown analysis of pavements has been developed using plastic strain energy as shakedown criteria via considering a special loading *** proposed method is verified by using a homogeneous isotropic half ***,the method is applied to analyze a two-layered *** dependence of shakedown limit on material properties of pavements is investigated in *** to the analysis results,some valuable references are suggested for the selection of materials for accurate evaluation of the bearing performance of pavement under traffic loading.

关键词： pavements shakedown material properties yield criterion finite element

Ginsenoside-Rg_6, a Novel Triterpenoid Saponin from the Stem-Leaves of Panax ginseng C. A. Mey.

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Chinese Chemical Letters 2000年第10期11卷 909-912页

作者： Xiu Wei YANG, long Yun li, jian Ming TIAN, Zhi Wei ZHANG, Jin Mei YE, Wei Fang Gu (National Research Laboratory of Natural & Biomimetic Drugs, Peking University, Beijing 100083) (Academy of Chinese Traditional Medicine and Materia Medica of Jilin Provinc Natl. Res. Lab. Nat. Biomimetic D. Peking University Beijing 100083 China Acad. Chinese Traditional Med. M. Changchun 130021 China

A novel dammarane-type triterpene oligoglycoside, named ginsenoside-Rg6 3, was isolated from the stem-leaves of Panax ginseng C. A. Mey., together with two known ones, 20(S)-ginsenoside-Rg2 1 and 20(R)-ginsenoside-Rg2 2. On the basis of chemical and physicochemical evidence , the structure of ginsenoside-Rg6 have been elucidated as 6-O-(-L-rhamnosyl-(1?2)-(-D-glucopyranosyl-dammarane-(E)-20(22), 24-diene-3(, 6(, 12(-triol.

关键词： Panax ginseng C. A. Mey. stem-leaves triterpenoid ginsenoside-Rg_6.

Plasma density transition-based electron injection in laser wake field acceleration driven by a flying focus laser

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Chinese Physics B 2023年第4期32卷 302-310页

作者：耿盼飞陈民安相炎刘维媛祝昕哲李建龙李博原盛政明 Key Laboratory for Laser Plasmas(Ministry of Education) School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center of IFSA(CICIFSA) Shanghai Jiao Tong UniversityShanghai 200240China

By using a high-intensity flying focus laser,the dephasingless[***.124134802(2020)]or phase-locked[***.14475(2020)]laser wakefield acceleration(LWFA)can be realized,which may overcome issues of laser diffraction,pump depletion,and electron dephasing which are always suffered in usual *** scheme thus has the potentiality to accelerate electrons to Te V energy in a single acceleration ***,the controlled electron injection has not been self-consistently included in such *** external injection was suggested in previous theoretical studies,which requires other accelerators and is relatively difficulty to ***,we numerically study the actively controlled density transition injection in phase-locked LWFA to get appropriate density profiles for amount of electron *** study shows that compared with LWFA driven by lasers with fixed focus,a larger plasma density gradient is *** experience both transverse and longitudinal loss during acceleration due to the superluminal group velocity of the driver and the variation of the wakefield ***,the periodic deformation and fracture of the flying focus laser in the high-density plasma plateau make the final injected charge also depend on the beginning position of the density *** studies show a possible way for amount of electron injection in LWFA driven by flying focus lasers.

关键词： density transition injection laser wakefield acceleration flying focus laser