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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 369-379页

作者： mei z.ang Wenhao Li Yangfei Chen Yang Jiang Xiaofei Guo Han Dong School of Materials Science and Engineering Shanghai UniversityShanghai 200444China State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200444China

The microstructural evolution of a cold-rolled and intercritical annealed medium-Mn steel(Fe-0.10C-5Mn)was investigated during uniaxial tensile ***-situ observations under scanning electron microscopy,transmission electron microscopy,and X-ray diffraction analysis were conducted to characterize the progressive transformation-induced plasticity process and associated fracture initiation *** findings were discussed with the local strain measurements via digital image *** results indicated that Lüders band formation in the steel was limited to 1.5%strain,which was mainly due to the early-stage martensitic phase transformation of a very small amount of the less stable large-sized retained austenite(RA),which led to localized stress concentrations and strain hardening and further retardation of *** small-sized RA exhibited high stability and progressively transformed into martensite and contributed to a stably extended Portevin-Le Chatelier *** volume fraction of RA gradually decreased from 26.8%to 8.2%prior to *** the late deformation stage,fracture initiation primarily occurred at the austenite/martensite and ferrite/martensite interfaces and the ferrite phase.

关键词： medium-Mn steel retained austenite progressive transformation-induced plasticity effect local strain fracture initiation

Precise Large Deviations for Sums of Claim-size Vectors in a Two-dimensional Size-dependent Renewal Risk Model

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Acta Mathematicae Applicatae Sinica 2021年第3期37卷 539-547页

作者： Ke-ang FU Xin-mei SHEN Hui-jie LI Department of Statistics Zhejiang University City CollegeHangzhou 310015China School of Mathematical Sciences Dalian University of TechnologyDalian 116024China Shunfeng Express Shanghai 200120China

Consider a two-dimensional renewal risk model,in which the claim sizes{Xk;k≥1}form a sequence of *** of a non-negative random vector whose two components are *** that the claim sizes and inter-arrival times form a sequence of *** pairs,with each pair obeying a dependence structure via the conditional distribution of the inter-arrival time given the subsequent claim size being *** a precise large-deviation formula of the aggregate amount of claims is obtained.

关键词： consistent variation extended regular variation large deviations size-dependence two-dimensional risk model

Precise large deviations for sums of random vectors in a multidimensional size-dependent renewal risk model

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Applied Mathematics(A Journal of Chinese Universities) 2018年第4期33卷 491-502页

作者： SHEN Xin-mei FU Ke-ang zHONG Xue-ting School of Mathematical Sciences Dalian University of Technology School of Statistics and Mathematics Zhejiang Gongshang University

Consider a multidimensional renewal risk model, in which the claim sizes {Xk, k ≥1} form a sequence of independent and identically distributed random vectors with nonnegative components that are allowed to be dependent on each other. The univariate marginal distributions of these vectors have consistently varying tails and finite means. Suppose that the claim sizes and inter-arrival times correspondingly form a sequence of independent and identically distributed random pairs, with each pair obeying a dependence structure. A precise large deviation for the multidimensional renewal risk model is obtained.

关键词： Precise large deviation Size-dependent Consistent variation Multidimensional risk model Renewal counting process

Phase-field-lattice Boltzmann study for lamellar eutectic growth in a natural convection melt

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China Foundry 2017年第5期14卷 373-378页

作者： ang z.ang zhi-peng Guo Shou-mei Xiong School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Tsinghua UniversityBeijing 100084China

In the present study, the influence of natural convection on the lamellar eutectic growth is determined by a phase-field-lattice Boltzmann study for Al-Cu eutectic alloy. The mass difference resulting from concentration difference led to the fluid flow, and a robust parallel and adaptive mesh refinement algorithm was employed to improve the computational efficiency without any compromising accuracy. Results show that the existence of natural convection would affect the growth undercooling and thus control the interface shape by adjusting the lamellar width. In particular, by alternating the magnitude of the solute expansion coefficient, the strength of the natural convection is changed. Corresponding microstructure patterns are discussed and compared with those under no-convection conditions.

关键词： natural convection lamellar width phase field model lattice Boltzmann method

A study of metal/die interfacial heat transfer behavior of vacuum die cast pure copper

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China Foundry 2020年第3期17卷 206-211页

作者： Hong-mei Yang zhou-meng Pu zhi-peng Guo ang z.ang Shou-mei Xiong School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology(Ministry of Education) Beijing 100084China Yunnan Copper Die-casting Technology Co. Ltd.Kunming 650001China

High pressure die casting copper is used to produce rotors for induction motors to improve *** were carried out for a special"step-shape"casting with different step *** on the measured temperature inside the die,the interfacial heat transfer coefficient(IHTC)at the metal/die interface during vacuum die casting was evaluated by solving the inverse *** IHTC peak value was 4.5×10^3-11×10^3 W·m^-2·K^-1 under the basic operation *** influences of casting pressure,fast shot speed,pouring temperature and initial die surface temperature on the IHTC peak values were *** show that a greater casting pressure and faster shot speed could only increase the IHTC peak values at the location close to the *** increase of pouring temperature and/or initial die surface temperature significantly increases the IHTC peak values.

关键词： vacuum die casting interfacial heat transfer behavior inverse method copper metal/die interface

Fabrication of nanoreactors based on polyoxoperoxometalates and enhancement of their catalytic activity

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Chinese Chemical Letters 2011年第7期22卷 875-878页

作者： mei Jie Wei Chun Li z.ang Cong Liang Sun ang Li Xiao Hong Wang Key Lab of Polyoxometalate Science of Ministry of Education Faculty of Chemistry Northeast Normal University Changchun 130024 China

The nanoreactors were fabricated by reacting amphiphilic quaternary ammoniums and polyoxoperoxometalates Kn[PW12-xTix. O40-x（O2）x] （x = 1, 2 and 3; n =5, 7 and 9）（K5[PW11TiO39（O2）], KT[PWloTi2038（O2）2] and K9[PW9Ti3O37（O2）3]）. Fourier transform infrared spectroscopy （FT-IR）, transmission electron microscopy （TEM） were used to characterize the resulting samples. This kind of nanocatalysts could promote NH4SCN＇ degradation into simple inorganic compounds such as SO4^2-, HCO3^- and NO3^- only using oxygen as an oxidant under room conditions.

关键词： Catalytic wet air oxidation Thiocyanate Polyoxometalate Nanocatalysts

Phase-field modeling of dendritic growth of magnesium alloys with a parallel-adaptive mesh refinement algorithm

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China Foundry 2021年第6期18卷 541-549页

作者： Bing-hui Tian Meng-wu Wu ang z.ang zhi-peng Guo Shou-mei Xiong Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

A two-dimensional phase field(PF)model was developed to simulate the dendritic solidification in magnesium alloy with hcp crystal *** applying a parallel-adaptive mesh refinement(Para-AMR)algorithm,the computational efficiency of the numerical model was greatly *** on the PF model,a series of simulation cases were conducted and the results showed that the anisotropy coefficient and coupling coefficient had a great influence on the dendritic morphology of magnesium *** dendritic growth kinetics was determined by the undercooling and equilibrium solute partition coefficient.A significant finding is acquired that with a large undercooling,the maximum solute concentration is located on both sides of the dendrite tip in the liquid,whereas the maximum solute concentration gradient is located right ahead of the dendrite tip in the *** dendrite tip growth velocity decreases with the increase of the equilibrium solute partition coefficient,while the variation trend of the dendrite tip radius is the *** analysis was carried out relating to the dendritic morphology and growth kinetics,and the simulated results are consistent with the theoretical models proposed in the previously published works.

关键词： magnesium alloy dendritic growth phase-field modeling solidification

Changes in intestinal mucosal immune barrier in rats with endotoxemia

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World Journal of Gastroenterology 2009年第46期15卷 5843-5850页

作者： Chong Liu ang Li Yi-Bing Weng mei-Li Duan Bao-En Wang Shu-Wen z.ang Departmentof Critical Care Medicine Beijing Friendship Hospital Affiliatedto Capital Medical University Beijing 100050 China Liver Research Center Beijing FriendshipHospital Affiliated to Capital Medical University Beijing100050 China Department of Infectious Disease andCritical Care Medicine Beijing Friendship Hospital Affiliatedto Capital Medical University Beijing 100050 China

AIM： To investigate the dysfunction of the immunological barrier of the intestinal mucosa during endotoxemia and to elucidate the potential mechanism of this dysfunction. METHODS： Male Wistar rats were randomly distributed into two groups： control group and lipopolysaccharide （LPS） group. Endotoxemia was induced by a single caudal venous injection of LPS. Animals were sacrificed in batches 2, 6, 12 and 24 h after LPS infusion. The number of microfold （M）-cells, dendritic cells （DCs）, CD4＋ T cells, CD8＋ T cells, regulatory T （Tr） cells and IgA＋ B cells in the intestinal mucosa were counted after immunohistochemical staining. Apoptotic lymphocytes were counted after TUNEL staining. The levels of interleukin （IL）-4, interferon （IFN）-γ, and forkhead box P3 （Foxp3） in mucosal homogenates were measured by ELISA. The secretory IgA （sIgA） content in the total protein of one milligram of small intestinal mucus was detected using a radioimmunological ***： This research demonstrated that LPS-induced endotoxemia results in small intestinal mucosa injury. The number of M-cells, DCs, CD8~ T cells, and IgA~ B cells were decreased while Tr cell and apoptotic lymphocyte numbers were increased significantly. The number of CD4＋ T cells increased in the early stages and then slightly decreased by 24 h. The level of IL-4 significantly increased in the early stages and then reversed by the end of the study period. The level of IFN-T increased slightly in the early stages and then decreased markedly by the 24 h time point. Level of Foxp3 increased whereas sIgA level ***： Mucosal immune dysfunction forms part of the intestinal barrier injury during endotoxemia. The increased number and function of Tr cells as well as lymphocyte apoptosis result in mucosal immunode- ficiency.

关键词： Endotoxemia Rats Intestinal mucosa Immunity

Blue light is more essential than red light for maintaining the activities of photosystem Ⅱ and Ⅰ and photosynthetic electron transport capacity in cucumber leaves

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Journal of Integrative Agriculture 2016年第1期15卷 87-100页

作者： MIAO Yan-xiu W ang Xiao-zhuo G AO Li-hong C HEN Qing-yun QU mei Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops College of Agriculture and Biotechnology China Agricultural UniversityBeijing 100193P.R.China

Blue and red lights differently regulate leaf photosynthesis. Previous studies indicated that plants under blue light generally exhibit better photosynthetic characteristics than those under red light. However, the regulation mechanism of related photosynthesis characteristics remains largely unclear. Here, four light qualities treatments （300 μmol m-2 s-1） including white fluorescent light （FL）, blue monochromatic light （B, 440 nm）, red monochromatic light （R, 660 nm）, and a combination of red and blue light （RB, R：B=8：1） were carried out to investigate their effects on the activity of photosystem II （PSII） and photosystem I （PSI）, and photosynthetic electron transport capacity in the leaves of cucumber （Cucumis sativus L.） seedlings. The results showed that compared to the FL treatment, the R treatment significantly limited electron transport rate in PSII （ETR11） and in PSI （ETR1） by 79.4 and 66.3%, respectively, increased non-light induced non-photochemical quenching in PSII （q^No） and limitation of donor side in PSI （φND） and reduced most JIP-test parameters, suggesting that the R treatment induced suboptimal activity of photosystems and inhibited electron transport from PSII donor side up to PSI. However, these suppressions were effectively alleviated by blue light addition （RB）. Compared with the R treatment, the RB treatment significantly increased ETR, and ETR1 by 176.9 and 127.0%, respectively, promoted photosystems activity and enhanced linear electron transport by elevating electron transport from QA to PSI. The B treatment plants exhibited normal photosystems activity and photosynthetic electron transport capacity similar to that of the FL treatment. It was concluded that blue light is more essential than red light for normal photosynthesis by mediating photosystems activity and photosynthetic electron transport capacity.

关键词： cucumber photosystem II photosystem I electron transport

Refining constitutive relation by integration of finite element simulations and Gleeble experiments

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Journal of Materials Science & Technology 2019年第6期35卷 1039-1043页

作者： D.J. Yu D.S. Xu H. W ang z.B. zhao G.z. Wei R. Yang College of Sciences Northeastern University Shenyang 110004 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Thermo-mechanical coupled finite element calculations were carried out to simulate the Gleeble compression of the samples of a titanium alloy(Ti60), and the results are analyzed and compared with the actual compression tests conducted on a Gleeble 3800 thermo-mechanical simulator. The changes in temperature, stress and strain distribution in the samples and the source of error on the constitutive relations from Gleeble hot compression test were analyzed in detail. Both simulations and experiments showed that the temperature distribution in the specimen is not uniform during hot compression, resulting in significant deformation inhomogeneity and non-ignorable error in the flow stress strain relation,invalidating the uniform strain assumption commonly assumed when extracting the constitutive relation from Gleeble tests. Based on the finite element simulations with iterative corrections, we propose a scheme to refine the constitutive relations from Gleeble tests.

关键词： Titanium alloy Constitutive relation Finite element Compression Temperature distribution