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Particle-in-cell simulation for effect of anode temperature on discharge characteristics of a Hall effect thruster

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Plasma Science and Technology 2018年第12期20卷 96-106页

作者： Hong LI Xingyu LIU Zhiyong GAO Yongjie DING liqiu wei Daren YU Xiaogang wang Plasma Propulsion Laboratory Harbin Institute of TechnologyHarbin 150001People's Republic of China AECC Harbin Dongan Engine(Group)Corporation Ltd Harbin 150066People's Republic of China Department of Physics Harbin Institute of TechnologyHarbin 150001People's Republic of China

Propellant gas flow has an important impact on the ionization and acceleration process of Hall effect thrusters （HETs）. In this paper, a particle-in-cell numerical method is used to study the effect of the anode temperature, i.e., the flow speed of the propellant gas, on the discharge characteristics of a HET. The simulation results show that, no matter the magnitude of the discharge voltage, the calculated variation trends of performance parameters with the anode temperature are in good agreement with the experimental ones presented in the literature. Further mechanism analysis indicates that the magnitude of the electron temperature is responsible for the two opposing variation laws found under different discharge voltages. When the discharge voltage is low, the electron temperature is low, and so is the intensity of the propellant ionization; the variation of the thruster performance with the anode temperature is thereby determined by the variation of the neutral density that affects the propellant utilization efficiency. When the discharge voltage is high, the electron temperature is large enough to guarantee a high degree of the propellant utilization no matter the magnitude of the anode temperature. The change of the thruster performance with the anode temperature is thus dominated by the change of the electron temperature and consequently the electron-neutral collisions as well as the electron cross-field mobility that affect the current utilization efficiency.

关键词： Hall effect thruster anode temperature neutral flow discharge characteristics particle-in-cell simulation

New Trends in Internal Migration in China： Profiles of the New-generation Migrants

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China & World Economy 2018年第1期26卷 18-41页

作者： liqiu Zhao Shouying Liu wei Zhang School of Labor and Human Resources Renmin University of China China School of Economics Renmin University of China China School of Marxism Tang Scholar Tsinghua University China

Three decades since the first wave of rural-urban migration, the new generation of migrant workers has become the main force of internal migration in China. The present paper comprehensively explores the profiles of the new generation of migrant workers in urban China. We find that the ＂new generation＂ migrants are more educated and skilled, and are likely to work in manufacturing and service industries than in the construction industry. Moreover, they tend to allocate more time to non-farm activities and have more months away from home per year in urban areas. In contrast to their predecessors, they tend to migrate to urban areas with their spouses, consume more in urban areas and send less money back home. Our findings suggest that the differences in features between the new generation of rural migrants and urban residents have become smaller and the integration of rural migrants into urban China has taken place gradually.

关键词： internal migration new generation of migrant workers rural-urban integration

1例FGA基因c.2185G>A变异所致遗传性异常纤维蛋白原血症并发深静脉血栓的分析

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临床检验杂志 2024年第2期42卷 117-120页

作者：潘晓浩何卫黄建芳郑晓勇温州市中西医结合医院检验科浙江温州325001 温州医科大学附属第一医院医学检验中心浙江温州325015

目的对1例遗传性异常纤维蛋白原血症(CD)患者出现深静脉血栓形成(DVT)进行分析,探讨CD与DVT的关系。方法临床资料收集及家系调查(共2代3人)。检测患者及其家系成员相关凝血指标。提取外周血基因组DNA进行PCR扩增,采用DNA直接测序法分析... 详细信息

目的对1例遗传性异常纤维蛋白原血症(CD)患者出现深静脉血栓形成(DVT)进行分析,探讨CD与DVT的关系。方法临床资料收集及家系调查(共2代3人)。检测患者及其家系成员相关凝血指标。提取外周血基因组DNA进行PCR扩增,采用DNA直接测序法分析患者纤维蛋白原(Fg)的FGA、FGB和FGG基因所有外显子、侧翼序列、5′和3′端非翻译区序列,及家系成员相应的变异位点区域。用PyMol软件构建基因变异前后蛋白模型。结果患者为行子宫肌瘤切除术入院,术后3天出现DVT。术前凝血指标检查显示患者的凝血酶原时间(PT)、凝血酶时间(TT)、Fg活性(Fg:C)和Fg抗原(Fg:Ag)分别为14.9 s、33.3 s、0.94 g/L和2.10 g/L;其母亲上述4项指标分别为14.7 s、32.8 s、0.97 g/L和2.35 g/L。DNA测序发现患者及其母亲的FGA基因第6号外显子均存在c.2185G>A杂合错义变异(***729Lys)。蛋白模型分析显示,***729Lys变异使Fg结构发生了改变。结论该先证者FGA基因第6号外显子c.2185G>A(NM_000508)杂合错义变异与其Fg:C减低有关,可能也是该患者出现DVT的原因之一。

关键词：遗传性异常纤维蛋白原血症基因变异深静脉血栓形成

Morphological control of SnTe nanostructures by tuning catalyst composition

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Nano Research 2015年第9期8卷 3011-3019页

作者： Yichao Zou Zhigang Chen Jing Lin xiaohao Zhou wei Lu John Drennan Jin Zou Materials Engineering The University of Queensland Brisbane QLD 4072 Australia National Laboratory for Infrared Physics Shanghai Institute of Technical Physics Chinese Academy of Sciences 500 Yu-Tian Road Shanghai 200083 China Centre for Microscopy and Microanalysis The University of Queensland Brisbane QLD 4072 Australia

A method of controlling the morphology of SnTe nanostructures produced by a simple chemical vapor deposition is presented, in which Au-containing catalysts with different Au concentrations are used to induce specific growth behavior. Triangular SnTe nanoplates with a {100} dominated surface and {100}, {111} and {120} side facets were induced by AuSn catalysts, whereas 〈010〉 SnTe nanowires with four nonpolar {100} side-facets were produced using AusSn catalysts. Through detailed structural and chemical characterization, coupled with surface energy calculations, it is found that nanowire growth is thermodynamically controlled via a vapor-solid-solid growth mechanism, whereas nanoplate growth is kinetically controlled via a vapor-liquid-solid growth mechanism. Therefore, this study provides a fundamental understanding of the catalyst＇s role in the growth of IV-VI compound nanostructures.

关键词： tin telluride,chemical vapor deposition,morpholog'ficatalyst composition,topological insulator,thermoelectrics

Numerical study of the effect of aft-loaded magnetic field on multiple ionizations in Hall thruster

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Plasma Science and Technology 2022年第7期24卷 45-52页

作者： Demai ZENG Hong LI Jinwen LIU Yongjie DING liqiu wei Daren YU wei MAO Lab of Plasma Propulsion Harbin Institute of TechnologyHarbin 150001People's Republic of China Key Laboratory of Aerospace Plasma Propulsion Ministry of Industry and Information TechnologyHarbin 150001People's Republic of China Qingdao Haier Smart Technology Qingdao 266100People's Republic of China Beijing Institute of Control Engineering Beijing 100190People's Republic of China

It is assumed that the shift of a strong magnetic field region with a positive gradient from exit plane to outside, namely the transit from a normal loaded magnetic field to an aft-loaded one, enhances the multiple ionization process in the magnetically shielded Hall thruster. To confirm this conjecture, a comparative study is carried out numerically with a particle-in-cell method. The simulation results prove that compared with the normal loaded magnetic field, the application of aft-loaded magnetic field enhances the multiple ionization process. This study further analyzes the ionization characteristics of the transition from low-charged ions to high-charged ions under two magnetic field conditions and the influence of the magnetic strength of aft-loaded magnetic field on the multiple ionization characteristics. The study described herein is useful for understanding the discharge characteristics of Hall thruster with an aft-loaded magnetic field.

关键词： Hall thruster aft-loaded magnetic field multiple ionization electron temperature

Advertisement Call Variability in the Black-spined Toad Bufo melanostictus (Anura: Bufonidae) during the Breeding Season in Lishui, Zhejiang, China

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Asian Herpetological Research 2012年第2期3卷 157-162页

作者： Li wei Lihua ZHAO xiaohao MA Xiaoli FAN Xiaomei MA Zhihua LIN School of Life and Environmental Sciences Hangzhou Normal University College of Ecology Lishui University

Advertisement calls play an important role in influencing female mate choice and are regarded as one of the key characters responsible for reproductive isolation and speciation events in frogs and toads. The black-spined toad, Bufo melanostictus, is one of the most common amphibians in Southeast Asia and is frequently observed in human habitations throughout its distributional range. The advertisement calls of the toad have not been well described. Here, we report the advertisement calls of this species from Lishui, Zhejiang, China during its breeding season. The advertisement calls of B. melanostictus are composed of single notes with a single harmonic frequency emitted sporadically. The call parameters recorded in this study were highly variable across recording times and with different body sizes. Dominant frequency was negatively correlated with body size. Comparing the calls of the B. melanostictus population from Lishui with the populations from five other localities(Bangkok, Thailand; Coorg, India; Burma, Myanmar; Bali, Indonesia; Halimun-Salak National Park, Indonesia), we found that call structure was similar among five different populations with no harmonics, while the Halimun-Salak National Park population contained two clear harmonics. Dominant frequency was similar between Bali(1.56 kHz) and Coorg(1.6 kHz) populations, while it was highly variable among other populations. Besides call duration, call interval and pulse/call rate may also be significantly different among the comparing populations. Pooling the available data, we observed some similarities and differences in call parameters among the six populations.

关键词： Anura vocalization Bufo melanostictus acoustic parameters advertisement call artificial pond

Investigation of short-channel design on performance optimization effect of Hall thruster with large height–radius ratio

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Plasma Science and Technology 2022年第2期24卷 1-9页

作者： Haotian FAN Yongjie DING Chunjin MO liqiu wei Hong LI Daren YU Plasma Propulsion Lab Institute of Advanced PowerHarbin Institute of TechnologyHarbin 150001People's Republic of China Key Laboratory of Aerospace Plasma Propulsion Ministry of Industry and Information TechnologyHarbin 150001People's Republic of China

In this study,the neutral gas distribution and steady-state discharge under different discharge channel lengths were studied via numerical *** results show that the channel with a length of 22 mm has the advantage of comprehensive discharge *** this time,the magnetic field intensity at the anode surface is 10%of the peak magnetic field *** analysis shows that the high-gas-density zone moves outward due to the shortening of the channel length,which optimizes the matching between the gas flow field and the magnetic field,and thus increases the ionization *** outward movement of the main ionization zone also reduces the ion loss on the wall ***,the propellant utilization efficiency can reach a maximum of 96.8%.Moreover,the plasma potential in the main ionization zone will decrease with the shortening of the *** excessively short-channel will greatly reduce the voltage utilization *** thrust is reduced to a minimum of 46.1 m ***,because the anode surface is excessively close to the main ionization zone,the discharge reliability is also difficult to *** was proved that the performance of Hall thrusters can be optimized by shortening the discharge channel appropriately,and the specific design scheme of short-channel of HEP-1350 PM was defined,which serves as a reference for the optimization design of Hall thruster with large height–radius *** shortchannel design also helps to reduce the thruster axial dimension,further consolidating the advantages of lightweight and large thrust-to-weight ratio of the Hall thruster with large height–radius ratio.

关键词： Hall thruster large height-radius ratio short-channel design discharge performance numerical simulation

When Students Become“Prisoners”:A Game Theory Analysis of Internship by Beijing College Students

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ECNU Review of Education 2018年第2期1卷 44-73页

作者： xiaohao Ding wei Ha Le Kang W.John Morgan Graduate School of Education Peking University Cardiff University

Purpose-The oversupply of college graduates and increasing competition in the Chinese urban labor market have forced college students to undertake internships much earlier and to a greater intensity in the hope of boosting their employment *** may be argued that the considerable time and energy thus spent on internships is deleterious to their university *** paper considers the factors that determine the intensity of an internship ***/Approach/Methods-Building on a Cobb-Douglas utility function,the paper constructs a Prisoners’Dilemma game to model the internship behavior of Chinese college students,and then examines the determinants of internship using data from a 2011 survey of approximately 10,000 Chinese college students from 47 higher education institutions in the Beijing metropolitan area and multivariate regression ***-Empirical results confirm three key hypotheses derived from our model:first,students’perceptions of higher differentials across available jobs in the labor market entice them to intern excessively;second,the improving quality of college teaching and the consequent benefit for knowledge acquisition mitigates the need for excessive internship;third,student preferences for fundamental knowledge acquisition also tilts the balance towards more study and less ***/Value-These findings suggest that in the context of a tight graduate labor market,improving the quality of college teaching provides a viable alternative to excessive internship by students.

关键词： Prisoners’dilemma game theory Cobb-Douglas utility function college student internship

地菍总黄酮抗2型糖尿病作用机制的网络药理学研究及实验验证

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现代药物与临床 2024年第1期39卷 23-33页

作者：莫烨云朱盼唐雨菲李笑笑杨秋莉李金燕韦丽秋李丽广西中医药大学药学院广西高校中药神经–代谢及免疫药理重点实验室广西南宁530200

目的利用网络药理学方法研究地菍总黄酮抗2型糖尿病的作用机制,通过动物实验对靶点进行验证。方法通过文献检索收集地菍总黄酮的化学成分,并在Swiss Target Prediction平台进行筛选;依据Swiss Target Prediction、GeneCards、TTD、Dru... 详细信息

目的利用网络药理学方法研究地菍总黄酮抗2型糖尿病的作用机制,通过动物实验对靶点进行验证。方法通过文献检索收集地菍总黄酮的化学成分,并在Swiss Target Prediction平台进行筛选;依据Swiss Target Prediction、GeneCards、TTD、DrugBank数据库预测和筛选地菍总黄酮成分治疗2型糖尿病的作用靶点;由Cytoscape3.7.1构建“成分–疾病–靶点”网络;String数据库构建靶点蛋白相互作用(PPI)网络;R语言对靶点基因进行基因本体(GO)富集分析及京都基因和基因组百科全书(KEGG)通路富集分析。以高脂饮食诱导和ip链脲佐菌素(STZ)方法构建2型糖尿病模型大鼠,将2型糖尿病模型造模成功的40只大鼠随机分成模型组,二甲双胍组(0.2 g/kg)组,地菍总黄酮(0.34、0.45、0.60 g/kg)组,每组8只,继续提供高脂饲料喂养,另设对照组。各组每天ig相应药物,1次/d,对照组和模型组ig 0.5%CMC-Na溶液,连续给药5周。记录大鼠体质量、饮水量和摄食量,检测大鼠血糖及血脂的相关指标,运用q PCR法检测地菍总黄酮对2型糖尿病大鼠肝组织中磷脂酰肌醇-3-激酶(PI3K)、蛋白激酶B(Akt)、腺苷酸活化蛋白激酶(AMPK)作用靶点的调控作用。Western blotting法检测各组大鼠肝脏中Akt、AMPK、固醇调节元件结合蛋白-1C(SREBP-1C)的蛋白相对表达量。结果从地菍总黄酮成分中筛选得到槲皮素、芹菜素、柚皮素等8种活性成分,作用于98个2型糖尿病靶点,GO功能与KEGG富集分析表明,地菍总黄酮抗糖尿病主要通过调节PI3K/Akt信号通路、AMPK相关信号通路等来发挥抗2型糖尿病的作用。动物实验证实,地菍总黄酮可降低2型糖尿病大鼠的空腹血糖(FBG),抑制血脂升高,上调2型糖尿病大鼠肝脏PI3K、Akt、AMPK m RNA表达,显著增加Akt、AMPK蛋白表达含量,降低SREBP-1C蛋白表达含量(P<0.01、0.05),对糖、脂代谢紊乱均具有改善作用,具有良好的抗2型糖尿病作用。结论验证了地菍总黄酮多成分、多靶点、多途径治疗2型糖尿病的特点,其抗糖尿病的作用机制可能与调节PI3K、Akt、AMPK、SREBP-1C靶点的表达水平,从而改善糖脂代谢紊乱有关,为后续更进一步研究作用机制提供参考。

关键词：地菍总黄酮 2型糖尿病网络药理学验证槲皮素芹菜素柚皮素磷脂酰肌醇-3-激酶蛋白激酶B 固醇调节元件结合蛋白-1C