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How Does Economic Policy Uncertainty Impact a Country's Position in Global Value Chains?

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China & World Economy 2024年第5期32卷 28-52页

作者： Jiaxuan Zhang Hongsheng Zhang Xuhang Shen bo meng Institute of Economics School of Social SciencesTsinghua UniversityChina China Academy of Digital Trade Zhejiang UniversityChina HSBC Business School Peking UniversityChina Institute of Developing Economies Japan External Trade OrganizationJapan Collaborative Innovation Center for Emissions Trading System Co-constructed by the Province and Ministry Hubei University of EconomicsChina

Economic globalization in the 21st century has been characterized by the rise and spread of global value chains(GVCs).It faces significant challenges due to increasing domestic and international policy uncertainty in the context of emerging mega risks like geopolitical tensions and climate *** paper begins by constructing a theoretical model for an open economy to study how risk-averse firms make decisions regarding the sourcing of intermediate inputs in an uncertain *** model solution proposes that firms will source fewer intermediate inputs from countries with more economic *** increase in domestic and foreign uncertainty will have opposite impacts on a country's position in *** this sense,we argue that a country tends to move downstream along GVCs if its own economic policies become more uncertain,and it tends to move upstream with an increase in the uncertainty of its trading partner *** regression analyses,based on data including the World Input-Output Database,World Development Indicators,the UN Comtrade database,and the Economic Policy Uncertainty Index,provide empirical support for this model-based *** findings highlight that a nation must consider foreign economic policy uncertainty and maintain domestic policy stability to participate in GVCs.

关键词： economic policy uncertainty global value chain GVC participation GVC position

Computer Simulation Study on Adsorption and Conformation of Polymer Chains Driven by External Force

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Chinese Journal of Polymer Science 2021年第2期39卷 258-266,I0009页

作者： He-Bei Gao Hong Li Xiao-Qin Zhang Xiang-Hong Wang Chao-Yang Li meng-bo Luo Department of Information Wenzhou PolytechnicWenzhou 325035China College of Computer Science and Artificial Intelligence Wenzhou UniversityWenzhou 325035China Department of Physics Hangzhou Normal UniversityHangzhou 310036China Department of Physics Zhejiang UniversityHangzhou 310027China

In this work,Monte Carlo simulations are used to study the critical adsorption behaviors of flexible polymer chains under the action of an external driving force F parallel to an attractive flat *** critical adsorption temperature Tc decreases linearly with increasing F,indicating that the driving force suppresses the adsorption of *** conformation of polymer is also affected by the driving ***,the effect of F is dependent on the competition between the driving force and *** strong force or at low temperature,the polymer is stretched along the direction of the force,while under weak force or at high temperature,the polymer is not *** the force is comparable to the temperature,the polymer may be stretched perpendicular to the driving force,and below Tc,we observe conformational transitions from parallel to perpendicular and again to parallel by decreasing the *** found that the perpendicular stretched conformation leads the polymer chain to synchronously move along the direction of the driving ***,the conformational transitions are attributed to the competition and cooperation between the driving force and the temperature.

关键词： Critical adsorption Polymer Driving force Conformation Monte Carlo simulation

Driven injection of a polymer into a spherical cavity:A Langevin dynamics simulation study

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Chinese Physics B 2021年第10期30卷 645-650页

作者： Chao Wang Fan Wu Xiao Yang Ying-Cai Chen meng-bo Luo Department of Physics Taizhou UniversityTaizhou 318000China Department of Physics Zhejiang UniversityHangzhou 310027China

The injection of a self-avoiding flexible polymer into a spherical cavity under a driving force is studied by using Langevin dynamics *** given polymer length(N)and driving force(f),the polymer can be completely injected into the cavity only when the radius of the cavity is larger than a transition radius(ReC).The dependence of ReC on N and f can be described by a scaling relation ReC∝N ^(1/3) f−δ.The value ofδchanges from 4/15 in the small f region to 1/6 in the moderate f region due to the screening of the excluded-volume interaction between *** find the complete injection time(τ)decreases monotonously with increasing the cavity radius or decreasing the polymer *** simulation results are in good agreement with the theoretical predictions from the free energy analysis and a simple kinetic model.

关键词： polymer injection simulation free energy

Stable isotope tracers identify sources and transformations of mercury in rice (Oryza sativa L.) growing in a mercury mining area

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Fundamental Research 2021年第3期1卷 259-268页

作者： Jiang Liu bo meng Alexandre.J.Poulain Qiyi meng Xinbin Fenga State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550002China Biology Department University of Ottawa30 Marie CurieOttawa ON K1N 6N5Canada Center for Excellence in Quaternary Science and Global Change Chinese Academy of SciencesXi'an 710061China

Methylmercury (MeHg) contaminated rice is a global issue, particularly in mercury-polluted areas, posing a potential threat to human health. The sources and transformations of mercury (Hg) species in rice are critical points that are not yet fully understood. In this study, field experimental pots together with a stable Hg isotope tracing technique were used to provide direct evidence of the sources and transformations of Hg species in rice plants. Enriched inorganic Hg (IHg) isotope (200Hg(NO3)2) was spiked into paddy soils, and the concentrations of inorganic Hg tracer (I200Hg), MeHg tracer (Me200Hg), and ambient Hg species (IHg and MeHg) were measured in the tissues of rice plants and their corresponding soil samples during the rice growing season. Here, we show that, in addition to the atmosphere, the soil is an important source of IHg to rice grains and was previously largely underestimated. We also show that MeHg is formed in paddy soil via microbial IHg methylation, absorbed through the rice root, translocated from the root to above-ground parts, and finally accumulated in rice grains. Although in vivo methylation of IHg in rice plants is unlikely to occur during the rice growing season, we observed in vivo demethylation of MeHg in the above-ground parts of rice plants, possibly via photolytic demethylation. Promoting in vivo demethylation of MeHg may be an effective approach to mitigate MeHg accumulation in rice grains.

关键词： Rice Hg isotope tracer Source Translocation Methylation/demethylation

Distribution and speciation of mercury in the Hongfeng Reservoir,Guizhou Province, China

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Chinese Journal Of Geochemistry 2008年第1期27卷 97-103页

作者： HE Tianrong FENG Xinbin GUO Yanna QIU Guangle YAN Haiyu meng bo State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China Graduate School of the Chinese Academy Sciences Beijing 100039 China

The water, pore water, sediment, and fish samples were collected from the Hongfeng Reservoir in No- vember 2003 and February 2004 in accordance with trace metal protocols. The average concentrations of total mer- cury (THg), dissolved mercury (DHg), reactive mercury, dissolved gaseous mercury, total methylmercury, and dis- solved methylmercury in the water columns were 8.00, 5.70, 0.63, 0.05, 0.16, and 0.07 ng/L, respectively. THg and DHg in the water columns, THg in pore water and THg in lake sediments of the Hongfeng Reservoir showed the level of mercury in the Hongfeng Reservoir was higher than in other natural waters in the world due to the loading of a lot of waste water with relatively high concentrations of mercury, whereas methylmercury concentrations in fish (wet weight) varied from 1.73–51.00 ng/g, much lower than in most remote lakes and reservoirs reported in northern Europe and North America. Methylmercury distributions in pore water and sediments showed methylation oc- curred mainly in the upper several centimeters of sediment cores in the Hongfeng Reservoir. The concentrations of dissolved organic carbon, total suspended particles, total Hg, and methylmercury were higher at Houwu than those at Daba in November 2003. It is suggested that other pollutants such as N and P from fishing farm and other waste water at Houwu,which resulted in deterioration of water quality, affected the concentrations and distributions of mercury species in the reservoir.

关键词：水银物种生物环境中国化合物

A quantitative analysis method for contact force of mechanism with a clearance joint based on entropy weight and its application in a six-bar mechanism

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Chinese Physics B 2022年第4期31卷 394-403页

作者： Zhen-Nan Chen meng-bo Qian Fu-Xing Sun Jia-Xuan Pan Department of Mechanical Engineering Zhejiang A&F UniversityHangzhou 311300China

Contact force in a clearance joint affects the dynamic characteristics and leads to nonlinear response of the *** is necessary to assess the nonlinearity of contact force ***,a new method named contact-force entropy weight is proposed in this *** method presents a comprehensive description of the judgment matrix in the X,Y,and Z *** assess the influence degrees of different clearances and angular velocities on the contact force,the method is applied to numerical calculation and simulation of a six-bar mechanism with a clearance joint to illustrate its application and investigate the influence degree of angular velocity and clearance on the contact *** combining the simulation results and theoretical calculations,the influence degrees of different clearances and angular velocities on the contact-force entropy weight of the six-bar mechanism with a clearance joint are *** is found that the angular velocity has a significant influence on the contact force entropy weight of the clearance joint,showing that the contact-force entropy weight is a feasible new method of assessing non-linearity of contact force *** method gives a theoretical reference for quantitatively analyzing the nonlinear dynamics.

关键词： clearance joint entropy weight six-bar mechanism quantitative analysis

Polybrominated Diphenyl Ethers in Surface Sediment from Songhua River Basin,Northeast of China

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Journal of Harbin Institute of Technology(New Series) 2015年第3期22卷 63-68页

作者： bo meng Liyan Liu Wanli Ma Wenlong Li Weiwei Song Yifan Li International Joint Research Center for Persistent Toxic Substances ( IJRC-PTS) State Key Laboratory of Urban Water Resource and EnvironmentSchool of Municipal and Environmental EngineeringHarbin Institute of Technology School of Science Harbin University

Sixty sediment samples were collected from the main Songhua River in three years. Twelve polybrominated diphenyl ether( PBDE) congeners( BDE17,28,47,66,99,100,153,154,138,183,and BDE-209) were detected to state the pollution situation. The results showed that the total concentration of total PBDEs ranges from 0. 424 to 23. 0 ng / g dry weight,with the mean of 3. 02 ng / g,and the total PBDEs concentration is at relative low level compared with those worldwide. The congener profile showed that BDE-209 is the dominant congener that accounts for more than 80. 1% of total PBDEs in sediments,followed by BDE-47 and BDE-99. These profiles are consistent with a high consumption of Deca-BDEs for the brominated flame retardant market in China. The results of spatial and seasonal observations indicated that local sources,temperature variation, and hydrologic conditions are significant factors on PBDEs concentrations. Hazard quotients suggested that PBDEs pose no potential risk to benthic organisms in detected area at present.

关键词： polybrominated diphenyl ether(PBDE) Songhua River sediment source risk assessment

Brain ischemia induces serine phosphorylation of neuronal nitric oxide synthase by Ca2+/calmodulin-dependent protein kinase II in rat hippocampus

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Acta Pharmacologica Sinica 2004年第5期25卷 75-80页

作者： Xue-bo YAN, Fan-jie meng, bo SONG, Guang-yi ZHANG2Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Xuzhou 221002, China Research Center for Biochemistry and Molecular Biology Xuzhou Medical College

AIM: To investigate whether brain ischemia induces serine phosphorylation of neuronal nitric oxide synthase(nNOS) by Ca2+/calmodulin-dependent protein kinase II (CaMKII) and the interaction between CaMKIIa and nNOSin rat hippocampus. METHODS: Brain ischemia was induced by bilateral carotid artery occlusion *** and the interaction of proteins were studied by immunoprecipitation and immunoblotting. Weinvestigated during brain ischemia serine phosphorylation and amount of nNOS in crude membranes fraction (P)and cytosolic fraction (S), interaction between CaMKIIa and nNOS, and the effects of 1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN-62, a selective inhibitor of CaMKII) on phos-phorylation and the interaction of proteins in P. RESULTS: Serine phosphorylation of nNOS in P increased persis-tently during brain ischemia, and 15 min ischemia-induced serine phosphorylation of nNOS was attenuated signifi-cantly by KN-62. But there was no serine phosphorylation of nNOS in S. The distributions of nNOS were notaffected by ischemia and KN-62. However, the binding levels of both CaMKIIa with nNOS and Thr286autophosphorylated CaMKIIa with nNOS increased after ischemia, and were diminished by KN-62. CONCLUSION:CaMKII interacted with nNOS and regulated serine phosphorylation of nNOS during brain ischemia.

关键词： serine phosphorylation nitric oxide synthase calmodulin kinase KN 62 brain ischemia hippo-campus

Continuous suture of the pancreatic stump and Braun enteroenterostomy in pancreaticoduodenectomy

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World Journal of Gastroenterology 2015年第9期21卷 2731-2738页

作者： Hong-bo meng bo Zhou Fan Wu Jie Xu Zhen-Shun Song Jian Gong Mahbuba Khondaker Bin Xu Department of General Surgery Shanghai 10th People’s HospitalTongji University School of Medicine Department of Obstetrics and Gynecology Shanghai 10th People’s HospitalTongji University School of Medicine GI Division Renji HospitalShanghai Institute of Digestive DiseasesShanghai Jiao-Tong University School of Medicine Tongji University School of Medicine

AIM:To investigate a new modification of pancreaticoduodenectomy(PD)-a mesh-like running suturing of the pancreatic remnant and Braun's ***:Two hundred and three patients underwent PD from 2009 to 2014 and were classified into two groups:Group A(98 patients),who received PD with a mesh-like running suturing for the pancreatic remnant,and Braun's enteroenterostomy; and Group B(105 patients),who received standard *** data,intraoperative findings,postoperative morbidity and perioperative mortality between the two groups were compared by univariate and multivariate ***:Demographic characteristics between Group A and Group B were *** were no significant differences between the two groups concerning perioperative mortality,and operative blood loss,as well as the incidence of the postoperative morbidity,including reoperation,bile leakage,intraabdominal fluid collection or infection,and postoperative *** relevant postoperative pancreatic fistula(POPF) and delayed gastric emptying(DGE) were identified more frequently in Group B than in Group *** A(PD with a mesh-like running suturing of the pancreatic remnant and Braun's enteroenterostomy) was independently associated with decreased clinicallyrelevant POPF and DGE,with an odds ratio of 0.266(95%CI:0.109-0.654,P =0.004) for clinically relevant POPF and 0.073(95%CI:0.010-0.578,P =0.013) for clinically relevant ***:An additional mesh-like running suturing of the pancreatic remnant and Braun's enteroenterostomy during PD decreases the incidence of postoperative complications and is beneficial for patients.

关键词： Pancreaticoduodenectomy Delayed gastric emptying B