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Effects of Ca(Y)-Si modifier on interface morphology and solute segregation during directional solidification of an austenite medium Mn steel

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Journal of University of Science and Technology Beijing 2005年第4期12卷 335-339页

作者： Gaofei Liang Zhenming xu jianguo Li School of Environmental Science and Engineering Shanghai Jiaotong University Shanghai 200240 China

The austenite medium Mn steel modified with controlled additions of Ca, Y, Si were directionally solidified using the vertical Bridgman method to study the effects of Ca（Y）-Si modifier on the solid-liquid （S-L） interface morphology and solute segregation. The interface morphology and the C and Mn segregation of the steel directionally solidified at 6.9 μtrn/s were investigated with an image analysis and a scanning electron microscope equipped with energy dispersive X-ray analysis. The 0.5wt% Ca-Si modified steel is solidified with a planar S-L interface. The interface of the 1.0wt% Ca-Si modified steel is similar to that of the 0.5wt% Ca-Si modified steel, but with larger nodes. The 1.5wt% Ca-Si modified steel displays a cellular growth parttern. The S-L interface morphology of the 0.5wt% Ca-Si＋1.0wt% Y-Si modified Mn steel appears as dendritic interface, and primary austenite dendrites reveal developed lateral branching at the quenched liquid. In the meantime, the independent austenite colonies are formed ahead of the S-L interface. A mechanism involving constitutional supercooling explains the S-L interface evolution. It depends mainly on the difference in the contents of Ca, Y, and Si ahead of the S-L interface. The segregation of C and Mn ahead of the S-L interface enhanced by the modifiers is observed.

关键词： austenite Mn steel modification solid-liquid (S-L) interface morphology solute segregation directional solidification

World Pest Day: Not for Pests, But for People

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China CDC weekly 2020年第24期2卷 429-430页

作者： jianguo xu Chinese Academy of Engineering Chinese Pest Control Association State Key Laboratory of Infectious Disease Prevention and Control National Institute for Communicable Disease Control and PreventionChina CDC

World Pest Day was inaugurated by the Chinese Pest Control Association and several organizations such as the Federation of Asian and Oceania Pest Managers Associations,the National Pest Management Association of US,Confederation of European Pest Management Associations,World Health Organization(WHO)Collaborating Centre for Vector Surveillance and Management,and State Key Laboratory of Infectious Disease Prevention and Control(China CDC).It was endorsed by 42 academicians from the Chinese Academy of Science and Chinese Academy of Engineering,as well as 21 Members of the National Political Consultative Committee of *** 6 is reserved annually to raise awareness among the public,government,and media about the important role that the pest control industry plays in protecting health,food,property and the environment from pest threats.

关键词： annually China. Pest

Thermal Error Modeling Method with the Jamming of Temperature-Sensitive Points'Volatility on CNC Machine Tools

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Chinese Journal of Mechanical Engineering 2017年第3期30卷 566-577页

作者： Enming MIAO Yi LIU jianguo xu Hui LIU school of instrument science and opto-electronics engineering hefei university of technologyHeifei 230009China

Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models＇ robustness is studied by regarding the Leaderway-V450 machining center as the object. Through the analysis of actual spindle air cutting experimental data on Leaderway-V450 machine, it is found that the temperature-sensitive points used for modeling is volatility, and this volatility directly leads to large changes on the collinear degree among modeling independent variables. Thus, the forecasting accuracy of multivariate regression model is severely affected, and the forecasting robustness becomes poor too. To overcome this effect, a modeling method of establishing thermal error models by using single temperature variable under the jamming of temperature-sensitive points＇ volatility is put forward. According to the actual data of thermal error measured in different seasons, it is proved that the single temperature variable model can reduce the loss of fore- casting accuracy resulted from the volatility of tempera- ture-sensitive points, especially for the prediction of cross quarter data, the improvement of forecasting accuracy is about 5 μm or more. The purpose that improving the robustness of the thermal error models is realized, which can provide a reference for selecting the modelingindependent variable in the application of thermal error compensation of CNC machine tools.

关键词： CNC machine tool Thermal error Temperature-sensitive points Forecasting robustnessUnivariate modeling

China＇s Internet Finance： A Critical Review

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China & World Economy 2017年第4期25卷 78-92页

作者： jianguo xu Associate Professor National School of Development and Institute of Digital Finance Peking University China

China＇s Internet finance industry developed explosively from 2012 to 2015. Undersupply of finaneial services, progress of information technology and accommodative regulations for Internet finance jointly explain the explosive development. Regulation tightened after the small-scale P2P lending crisis in 2015. The present paper discusses the role of information technology and mega data analysis in financial services, with particular attention paid to some popular misconceptions. The paper predicts that large financial institutions and information technology companies will play a dominant role in the future development of lnternet finance.

关键词： financial regulation financial repression information technology mega data analysis

Antarctic thermolabile uracil-DNA-glycosylase- supplemented multiple cross displacement amplification using a label-based nanoparticle lateral flow biosensor for the simultaneous detection of nucleic acid sequences and elimination of carryover contamination

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Nano Research 2018年第5期11卷 2632-2647页

作者： Yi Wang Hui Li Yan Wang Huaqing xu jianguo xu Changyun Ye State Key Laboratory of Infectious Disease Prevention and Control National Institute for Communicable Disease Control and Prevention Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases Chinese Center for Disease Control and Prevention Beijing 102205 China Department of Microbiology Guizhou Medical University Guiyang 550004 China The Sixth People's Hospital of Zhengzhou Zhengzhou 450000 China

Here, we report a novel and universal methodology,termed ＂ntarctic thermolabile uracil-DNA-glycosylase （AUDG）-supplemented nucleic acid amplification techniques （NAAs） using a labeled-based nanoparticle lateral flow biosensor （LFB）＂（AUDG-NAAs-LFB）, which merges enzymatic （AUDG） digestion of contaminant amplicons with different nucleic acid amplification techniques （NAAs）, and uses a lateral flow biosensor （LFB） for the rapid and visual confirmation of the presence of a target nucleic acid sequence. AUDG-NNAs-LFB is a one-pot, closedvessel assay, that can effectively eliminate false-positive signals arising from either carryover contaminants or the interaction between labeled primers. A new LFB was devised for detecting three targets （two amplicons generated from amplification of target sequences, and a chromatography control）, without the need for probe- hybridization or additional incubation steps. As a proof of concept, multiple cross displacement amplification （MCDA）, which is a specific, sensitive, and rapid isothermal amplification method, was selected as the model amplification technique to demonstrate the feasibility of AUDG-NAAs-LFB. As a result, we demonstrate the applicability of the AUDG-MCDA-LFB method for simultaneously detecting high-risk human papillomaviruses genotypes 16 and 18, which are the most and second-most prevalent strains of the virus reported in women worldwide. We also confirm the principle behind the AUDG-MCDA- LFB assay and validate its sensitivity, reproducibility, and specificity using serial dilutions of the type-specific plasmids, as well as clinical samples. This proof- of-concept method （AUDG-MCDA-LFB） can be easily reconfigured to detect various nudeic acid sequences by redesigning the specific MCDA primers.

关键词： Antarctic thermolabile uracil-DNA-glycosylase(AUDG) nucleic acid amplification techniques (NAAs) multiple cross displacement amplification (MCDA) lateral flow biosensor (LFB) limit of detection (LOD) human papillomaviruses(HPV)

Experimental and Numerical Studies on the Diffusion of CO2 from Oil to Water

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Journal of Thermal Science 2020年第1期29卷 268-278页

作者： LI Binfei ZHANG Qiliang CAO Aiqing BAI Hao xu jianguo School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China Beijing Oil&Gas Pipeline Control Center PetroChinaBeijing 100007China School of Mechanical and Electronic Engineering China University of Petroleum(East China)Qingdao 266580China Jilin Oilfield PetroChinaSongyuan 138000China

Injecting CO2 into oil reservoirs can improve the oil recovery,meanwhile achieve CO2 *** diffusion of CO2 in oil-water systems has a substantial impact on this *** interface significantly affects the mass transfer of CO2 between oil and water *** this paper,based on the determination of the CO2 diffusion coefficient in oil or water phases,the diffusion processes of CO2 from oil to water were experimentally investigated under different pressures.A numerical method was proposed to calculate the pressure drop and the diffusion coefficient in the process of CO2 diffusion from oil to *** experimental results indicated that the CO2 diffusion coefficient in oil or water increased rapidly with pressure up to the critical pressure of CO2 and gradually slowed down *** CO2 diffusion from oil to water was much slower than that in oil or *** diffusion coefficient of CO2 from oil to water was one magnitude lower than that in the single liquid phase of oil or water,and the effect of pressure was not *** on the diffusion coefficient of CO2 in a single liquid phase and the proposed numerical method,the pressure drop and the numerical diffusion coefficient in the process of CO2 diffusion from oil to water were *** relative errors between the experimental and numerical results were within 9%.Therefore,the numerical method proposed herein can be used to predict the diffusion process of CO2 from oil to water and the diffusion coefficient associated with this process.

关键词： CO2-oil-water system CO2 diffusion mass transfer pressure decay method numerical method

Reverse microbial etiology:A research field for predicting and preventing emerging infectious diseases caused by an unknown microorganism

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Journal of Biosafety and Biosecurity 2019年第1期1卷 19-21页

作者： jianguo xu State Key Laboratory of Infectious Disease Prevention and Control National Institute for Communicable Disease Control and PreventionChinese Center for Disease Control and PreventionChangpingBeijing 102206PR China

To predict,detect,prepare for,and prevent potential emerging infectious diseases caused by unknown microorganisms in the future,we have proposed the research field of reverse microbial *** isolate and classify unknown microorganisms and assesse their ability to cause infection,an outbreak,or *** suggest a list of potential pathogens and propose a preparation,prevention,and control strategy to protect global health and global economy and to ensure global security.

关键词： prevention diseases etiology

Crystal structure of cytotoxin protein suilysin from Streptococcus suis

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Protein & Cell 2010年第1期1卷 96-105页

作者： Lingfeng xu Bo Huang Huamao Du xuejun CZhang jianguo xu xuemei Li Zihe Rao National Laboratory of Biomacromolecules Institute of BiophysicsChinese Academy of Sciences15 Datun RoadBeijing 100101China College of Biotechnology Southwest UniversityChongqing 400715China State Key Laboratory for Infectious Disease Prevention and Control National Institute for Communicable Disease Control and PreventionBeijing 102200China Protein Studies Program Oklahoma Medical Research Foundation825 N.E.13th streetOklahoma CityOK 73104USA

Cholesterol-dependent cytolysins(CDC)are pore forming toxins.A prototype of the CDC family members is perfringolysin O(PFO),which directly binds to the cell membrane enriched in cholesterol,causing cell ***,an exception of this general observation is intermedilysin(ILY)of Streptococcus intermedius,which requires human CD59 as a receptor in addition to cholesterol for its hemolytic activity.A possible explanation of this functional difference is the conformational variation between the C-terminal domains of the two toxins,particularly in the highly conserved undecapeptide termed tryptophan rich ***,we present the crystal structure of suilysin,a CDC toxin from the infectious swine pathogen Streptococcus *** PFO,suilysin does not require a host receptor for hemolytic activity;yet the crystal structure of suilysin exhibits a similar conformation in the tryptophan rich motif to *** observation suggests that the current view of the structure-function relationship between CDC proteins and membrane association is far from complete.

关键词： suilysin cholesterol-dependent cytolysin crystal structure

Decision-making model for risk management of cascade hydropower stations

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Journal of Southeast University(English Edition) 2008年第S1期24卷 22-26页

作者： Pan, Bangchuan Chi, Hong xu, jianguo Qi, Mingliang Institute of Policy and Management Chinese Academy of Sciences Beijing 100190 China Graduate University Chinese Academy of Sciences Beijing 100049 China

In a medium-term electricity market,in order to reduce the risks of price and inflow uncertainties, the cascade hydropower stations may use the options contract with electricity supply companies. A profit-based model for risk management of cascade hydropower stations in the medium-term electricity market is presented. The objective function is profit maximization of cascade hydropower stations. In order to avoid the risks of price and inflow uncertainties, two different risk-aversion constraints: a minimum profit constraint and a minimum conditional value-at-risk, are introduced in the model. In addition, the model takes into account technology constraints of the generating units, which includes reservoir flow balance, reservoir capacity limits, water discharge constraints, etc. The model is formulated as a mixed integer nonlinear programming problem. Because the search space of the solution is very large, a genetic algorithm is used to deal with the problem.

关键词： cascade hydropower station mixed integer nonlinear programming risk management medium-term electricity market