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Enhanced strength and ductility in Al-Zn-Mg-Cu alloys fabricated by laser powder bed fusion using a synergistic grain-refining strategy

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Journal of Materials Science & Technology 2022年第29期124卷 41-52页

作者： Xiaohui liu Yunzhong liu Zhiguang Zhou Qiangkun zhan National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510641China

Grain refinement is critical to surpassing the bottlenecks of inherent hot tearing of high-strength aluminum alloys fabricated by additive manufacturing(AM).In this study,a synergistic grain-refining strategy including heterogeneous nucleation,solute-driven growth restriction and nanoparticle-induced growth restriction was introduced to control the microstructure of Al-Zn-Mg-Cu alloys during the laser powder bed fusion(LPBF)***-free Al-Zn-Mg-Cu alloys with significantly refined grains were safely fabricated via LPBF by coincorporation of Ti C and ***-situ L1-AlTi particles were produced to promote the heterogeneous *** grain growth was restricted by adding Ti solute,while introduced TiC nanoparticles(NPs)improved the density of heterogeneous nucleation sites and blocked grain growth *** resultant elimination of columnar grains and hot cracks in the(1 wt.%)TiC-and(0.8 wt.%)TiH-modified Al-Zn-Mg-Cu alloy resulted in excellent ultimate tensile strength(UTS)of 593±24 MPa,yield strength(YS)of 485±41 MPa and elongation(EL)of 10.0%±2.5%under the T6 *** study provides new insights into improving the grain microstructure and mechanical properties of high-strength aluminum alloys during LPBF.

关键词： Grain refinement High-strength aluminum alloys Laser powder bed fusion(LPBF) Al-Zn-Mg-Cu alloy

Application of hepatitis B virus replication mouse model

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World Journal of Gastroenterology 2010年第16期16卷 1979-1985页

作者： Gao, zhan liu, Feng-Jun liu, Li Zhou, Tao-You Lei, Jun Xu, Lu liu, cong Dai, Jie Chen, En-Qiang Tang, Hong W China Hosp Sichuan Univ Ctr Infect Dis Chengdu 610041 Sichuan Prov Peoples R China Sichuan Univ Div Infect Dis State Key Lab Biotherapy Chengdu 610041 Sichuan Prov Peoples R China N Sichuan Med Coll Affiliated Hosp Dept Infect Nanchong 637000 Sichuan Prov Peoples R China

AIM:To evaluate the value of the hepatitis B virus(HBV) replication mouse model with regard to several aspects of the study of HBV ***:To evaluate the HBV replication mouse model in detecting the efficacy of anti-HBV agents,the interferon inducer polyinosinic-polytidylin acid(polyIC) and nucleotide analogues adefovir and entecavir were administered to mice injected with wild type pHBV4.1,and the inhibiting effect of these agents on HBV DNA replication was *** identify the model's value in a replication ability study of HBV drug-resistant mutants and a HBx-minus mutant,telbivudine resistance mutants(rtM204I,ayw subtype),adefovir resistance mutants(rtA181V + rtN236T,ayw subtype) and HBxminus mutants were injected respectively,and their corresponding HBV DNA replication intermediates in mouse liver were ***:Compared with the wild type HBV replication mouse model without antiviral agent treatment,the HBV DNA replication intermediates of the polyICtreated group were decreased 1-fold;while in the entecavir-and adefovir-treated groups,the levels of HBV DNA replication intermediates were inhibited 13.6-fold and 1.4-fold,*** the mouse models injected with telbivudine resistance mutant,adefovir resistance mutant and HBx-minus mutant,HBV DNA replication intermediates could still be detected,but the levels of HBV DNA replication intermediates of these mutants decreased 4.5-fold,5.6-fold and 2.9-fold respectively,compared with the mouse model with wild type HBV ***:The HBV replication mouse model we established was a useful and convenient tool to detect the efficacy of antiviral agents and to study the replication ability of HBV mutants in vivo.

关键词： Hepatitis B virus Antiviral agents Drug resistance Mutants Mouse model

Disturbance observer based time-varying sliding mode control for uncertain mechanical system

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Journal of Systems Engineering and Electronics 2012年第1期23卷 108-118页

作者： Binglong cong Xiangdong liu Zhen Chen School of Automation Beijing Institute of Technology Beijing 100081 P. R. China Key Laboratory for Intelligent Control ＆ Decision on Complex Systems Beijing Institute of Technology Beijing 100081 P. R. China

It is now well known that the time-varying sliding mode control （TVSMC） is characterized by its global robustness against matched model uncertainties and disturbances. The accurate tracking problem of the mechanical system in the presence of the parametric uncertainty and external disturbance is addressed in the TVSMC framework. Firstly, an exponential TVSMC algorithm is designed and the main features are analyzed. Especially, the control parameter is obtained by solving an optimal problem. Subsequently, the global chattering problem in TVSMC is considered. To reduce the static error resulting from the continuous TVSMC algorithm, a disturbance observer based time-varying sliding mode control （DOTVSMC） algorithm is presented. The detailed design principle and the stability of the closed-loop system under the composite controller are provided. Simulation results verify the effectiveness of the proposed algorithm.

关键词： mechanical system time-varying sliding mode control (TVSMC) global sliding phase global chattering disturbance observer.

Effects of Mo on phase structure and up-conversion emissions of Er:Al_2O_3 nanocrystals

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Science China(Physics,Mechanics & Astronomy) 2012年第8期55卷 1417-1421页

作者： liu Dan cong Yan School of Physics and Materials Engineering Dalian Nationalities University Dalian 116600 China

A simple and efficient approach was presented to enhance up-conversion emissions significantly for the Er：Al2O3 nanocrystals by Mo support （Er-Mo：Al2O3） with a 976 nm laser diode excitation. Mo support had evident effects on the phase structure and up-conversion emissions for the Er：Al2O3 nanocrystals, which promoted the θ-（Al,Er）2O3 transformed to α-（Al,Er,Mo）203 phase, Compared with the Er：Al2O3, the maximal green and red up-conversion emissions intensities increased about 3×10^3 and 1.4×10^2 times for the Er-Mo：Al2O3 nanocrystals, respectively. It suggests that the enhancement of up-conversion emissions is caused by the high excited state energy transfer process from [4115/2, 3T2） state of the Er3＋-MoO2- dimer to the 4F7/2 level of E3＋.

关键词： Er doped Al2O3 up-conversion emissions Mo support sol-gel method

An Efficient Nanoparticle-Supported and Magnetically Recov-erable Copper(I)Catalyst for Synthesis of Furans from Ene-yne-ketone

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Chinese Journal of Chemistry 2015年第2期33卷 175-180页

作者： Yi liu zhan liu Yingde Cui School of Materials Science and Engineering Northwestern Polytechnical UniversityXi'anShaanxi 710072China Departmenl of Chemistry and Chemical Engineering Huaihua UniversityHuaihuaHunan 418000China Guangzhou Vocational College of Science and Technology GuangzhouGuangdong 510550China

A magnetic nano-supported Cu(I)catalyst was prepared and showed high activity for cyclization of ene-yne-ketone to synthesize *** catalyst was easily recovered from the reaction by using external magnets and reused 8 ... 详细信息

关键词： furans ene-yne-ketone magnetic nano-supported copper(I)catalyst cyclization

Microstructure refinement and work hardening in a machined surface layer induced by turning Inconel 718 super alloy

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International Journal of Minerals,Metallurgy and Materials 2018年第8期25卷 937-949页

作者： Xiao-ping Ren zhan-qiang liu School of Mechanical Engineering Shandong University Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of EducationShandong University

The microstructural changes in the machined surface layer of Ni-based super alloys essentially determine the final performance of the structural components of aerospace engines in which these alloys are *** this work,multiscale metallurgical observations using scanning electron microscopy,electron-backscatter diffraction microscopy,and transmission electron microscopy were conducted to quantitatively characterize the microstructure of the machined ***,to elucidate the factors that affect the formation of the refinement microstructure,the distributions of the deformation parameters(strain,strain rate,and temperature) in the machined subsurface were analyzed.A dislocation–twin interaction dynamic recrystallization mechanism for grain refinement during machining of Inconel 718 is ***,microhardness evolution induced by grain refinement in the machined surface is *** results suggest that the gradient microstructure and the work hardening can be optimized by controlling the cutting parameters during turning of Inconel 718.

关键词： grain refinement dislocation–twin interaction work hardening turning Inconel 718

Efficacy of the hypoxia-activated prodrug evofosfamide (TH-302) in nasopharyngeal carcinoma in vitro and in vivo

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Cancer Communications 2018年第1期38卷 179-187页

作者： Yan Huang Ying Tian Yuanyuan Zhao cong Xue Jianhua zhan Lin liu Xiaobo He Li zhang State Key Laboratory of Oncology in South China Collaborative Innovation Center for Cancer MedicineGuangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and TherapySun Yat-sen University Cancer CenterGuangzhou 510060GuangdongP.R.China Department of Medical Oncology Sun Yat-sen University Cancer CenterGuangzhou 510060GuangdongP.R.China Department of Experimental Research Sun Yat-Sen University Cancer CenterGuangzhou 510060GuangdongP.R.China Department of Medical Oncology The Fifth Affiliated HospitalSun Yat-Sen UniversityZhuhai 519000GuangdongP.R.China Department of Radiation Oncology The Fifth Affiliated HospitalSun Yat-Sen UniversityZhuhai 519000GuangdongP.R.China

Background:Tumor hypoxia is considered an important factor in metastasis and disease *** is a hypoxia-activated prodrug that selectively targets the hypoxic regions of solid *** hypoxia-inducible factor-1α(HIF-1α)is overexpressed in nasopharyngeal carcinoma(NPC)tissues,we performed the present study to evaluate the efficacy profile of evofosfamide in ***:We evaluated the efficacy of evofosfamide as a single agent or combined with cisplatin(DDP)in the NPC cell lines CNE-2,HONE-1 and HNE-1,and in nude mouse xenograft tumor ***:Evofosfamide exhibited hypoxia-selective cytotoxicity in NPC cell lines,with 50%inhibition concentration(IC50)values of 8.33±0.75,7.62±0.67,and 0.31±0.07μmol/L under hypoxia in CNE-2,HONE-1 and HNE-1 cells,*** sensitization ranged from ninefold to greater than 300-fold under hypoxia compared with normoxia *** combination of evofosfamide with DDP had a synergistic effect on cytotoxicity in the NPC cell lines by combination index values *** cycle G2 phase was arrested after treated with 0.05μmol/L evofosfamide under *** H2AX phosphorylation(γH2AX)(a marker of DNA damage)expression increased while HIF-1αexpression suppressed after evofosfamide treatment under hypoxic *** the HNE-1 NPC xenograft models,evofosfamide exhibited antitumor activity both as a single agent and combined with *** regions in xeno-graft tissue were reduced after both evofosfamide monotherapy and combined therapy with ***:Our results present preclinical evidence for targeting the selective hypoxic portion of NPC by evofosfa-mide as a single agent and combined with DDP and provide rationale for the potential clinical application of evofosfa-mide for the treatment of nasopharyngeal carcinoma.

关键词： Nasopharyngeal carcinoma(NPC) Hypoxia-induced factor-1α(HIF-1α) Hypoxia-activated prodrug Chemotherapy Xenograft tumor models

Fourier time spectral method for subsonic and transonic flows

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Acta Mechanica Sinica 2016年第3期32卷 380-396页

作者： Lei zhan Feng liu Dimitri Papamoschou School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Department of Mechanical and Aerospace Engineering University of CaliforniaIrvineCA 92697USA

The time accuracy of the exponentially accurate Fourier time spectral method（TSM） is examined and compared with a conventional 2nd-order backward difference formula（BDF） method for periodic unsteady flows. In particular, detailed error analysis based on numerical computations is performed on the accuracy of resolving the local pressure coefficient and global integrated force coefficients for smooth subsonic and non-smooth transonic flows with moving shock waves on a pitching airfoil. For smooth subsonic flows, the Fourier TSM method offers a significant accuracy advantage over the BDF method for the prediction of both the local pressure coefficient and integrated force coefficients. For transonic flows where the motion of the discontinuous shock wave contributes significant higherorder harmonic contents to the local pressure fluctuations,a sufficient number of modes must be included before the Fourier TSM provides an advantage over the BDF *** Fourier TSM, however, still offers better accuracy than the BDF method for integrated force coefficients even for transonic flows. A problem of non-symmetric solutions for symmetric periodic flows due to the use of odd numbers of intervals is uncovered and analyzed. A frequency-searching method is proposed for problems where the frequency is not known a priori. The method is tested on the vortex shedding problem of the flow over a circular cylinder.

关键词： Fourier time spectral method(TSM) Pitching airfoil Transonic flow Non-symmetric solution Computational efficiency Vortex shedding flow Frequency search

Multi-performance evaluation of high-throughput accelerated corrosion test for high-strength low-alloy 921A steel

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Journal of Iron and Steel Research International 2024年第5期31卷 1260-1278页

作者： cong-cong Du Ming-hua Qin zhan-fang Wu Dong-ling Li Lei Zhao Xiang-yang Li Hai-zhou Wang Beijing Advanced Innovation Center for Materials Genome Engineering National Center for Materials Service SafetyUniversity of Science and Technology BeijingBeijing100083China China Iron and Steel Research Institute Group Co. Ltd.Beijing100081China Beijing Advanced Innovation Center for Materials Genome Engineering Central Iron and Steel Research InstituteBeijing100081China

The corrosion behavior of high-strength low-alloy 921A steel in a simulated marine atmospheric environment was studied using a high-throughput experimental *** corrosion behavior,corrosion morphology,and corrosion products of 921A steels were analyzed using various techniques,including corrosion mass loss method,polarization curve,white-light interferometry,scanning electron microscopy,energy-dispersive spectrometry,microbeam X-ray fluorescence spectrometry,X-ray diffraction technique,and X-ray photoelectron *** test results indicated that 921A steel exhibits better corrosion resistance than Q450NQR1 steel in simulated harsh atmospheric environments,as evidenced by a lower corrosion mass loss rate throughout the corrosion *** corrosion products of both steels consisted ofα-FeOOH,Fe_(3)O_(4),andγ-FeOOH,withα-FeOOH being more prevalent in the rust layer of 921A steel than in Q450NQR1 *** inner rust layer of 921A steel also exhibited an appositional enrichment region of Cr,Ni,Mo,and V,leading to its superior corrosion resistance compared to that of Q450NQR1 *** efficacy of high-throughput accelerated corrosion experimental methods was highlighted for evaluating the corrosion resistance of steel materials in harsh environmental *** findings suggest that 921A steel exhibits better corrosion resistance compared to Q450NQR1 steel and has the potential to be more suitable in harsh marine atmospheric *** characterization of the rust layer structures and composition reveals the parallel enrichment of certain elements in the inner rust layer of 921A steel,which enhances its corrosion resistance.

关键词： Atmospheric corrosion High-throughput experimental method High-strength low-alloy steel Corrosion characteristics Rust layer Element enrichment