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搅拌头机械载荷在搅拌摩擦焊接中的作用的数值分析

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金属学报 2009年第8期45卷 994-999页

作者：鄢东洋史清宇吴爱萍 juergen Silvanus 清华大学机械工程系北京100084 European Aeronautic Defence and Space Company (EADS) Innovation Works Munich 81663 Germany

利用数值模拟技术分析搅拌头机械载荷在焊接过程中的作用,通过对比只考虑热载荷、考虑热载荷和搅拌头的下压力,综合考虑热载荷、搅拌头下压力和工作扭矩三种条件下的应力、应变和变形,结果发现,搅拌头下压力使焊后残余应力值大幅下降:... 详细信息

利用数值模拟技术分析搅拌头机械载荷在焊接过程中的作用,通过对比只考虑热载荷、考虑热载荷和搅拌头的下压力,综合考虑热载荷、搅拌头下压力和工作扭矩三种条件下的应力、应变和变形,结果发现,搅拌头下压力使焊后残余应力值大幅下降:搅拌头的工作扭矩是焊后残余应力、应变不对称分布的重要影响因素;并且搅拌头机械载荷使得薄板焊后残余变形的模式发生了完全相反的变化,由不考虑搅拌头载荷时的马鞍状变成了反马鞍状.

关键词：搅拌摩擦焊数值模拟残余应力残余应变残余变形

Hepatitis B virus replication

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World Journal of Gastroenterology 2007年第1期13卷 48-64页

作者： juergen Beck Michael Nassal Department of Internal Medicine II/Molecular Biology University Hospital FreiburgGermany

Hepadnaviruses, including human hepatitis B virus （HBV）, replicate through reverse transcription of an RNA intermediate, the pregenomic RNA （pgRNA）. Despite this kinship to retroviruses, there are fundamental differences beyond the fact that hepadnavirions contain DNA instead of RNA. Most peculiar is the initiation of reverse transcription： it occurs by protein-priming, is strictly committed to using an RNA hairpin on the pgRNA, ε, as template, and depends on cellular chaperones; moreover, proper replication can apparently occur only in the specialized environment of intact nucleocapsids. This complexity has hampered an in-depth mechanistic understanding. The recent successful reconstitution in the test tube of active replication initiation complexes from purified components, for duck HBV （DHBV）, now allows for the analysis of the biochemistry of hepadnaviral replication at the molecular level. Here we review the current state of knowledge at all steps of the hepadnaviral genome replication cycle, with emphasis on new insights that turned up by the use of such cellfree systems. At this time, they can, unfortunately, not be complemented by three-dimensional structural information on the involved components. However, at least for the ~ RNA element such information is emerging, raising expectations that combining biophysics with biochemistry and genetics will soon provide a powerful integrated approach for solving the many outstanding questions. The ultimate, though most challenging goal, will be to visualize the hepadnaviral reverse transcriptase in the act of synthesizing DNA, which will also have strong implications for drug development.

关键词： Chaperone-mediated reverse transcription HBV cccDNA Hepadnavirus, P protein Pregenomic RNA Protein-priming reverse transcriptase RNA encapsidation signal

Sensitivity and specificity of different staining methods to monitor apoptosis induced by oxidative stress in adherent cells

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Chinese Medical Journal 2003年第12期116卷 1923-1929页

作者：赵进顺 Alexandra Schmid-Kotsas Hans-juergen Gross Adolf Gruenert Max G. Bachem Department of Occupational and Environmental Medicine Department of Clinical Chemistry and Pathobiochemistry

Objective To study the sensitivity and specificity of different staining methods to monitor apoptosis induced by oxidative stress in adherent *** Sensitivity and specificity of several common methods for apoptosis determination were evaluated (Apo2.7-expression, Annexin V-binding, TUNEL-reaction, poly-(ADP-ribose)-polymerase-(PARP) cleavage and single-stranded-DNA (ssDNA) staining). Apoptosis was induced by oxidative stress generated by hydrogen peroxide in 3 cultured cells types growing as adherent monolayer (MiaPaCa-2, Hep-G2 and human skin fibroblasts), necrosis was induced by depletion of cellular ATP using sodium azide. Cells positively stained by the respective apoptosis assay were quantified and alterations of cell morphology were monitored by fluorescence microscopy. The date was analyzed by one-way analysis of variance and significance test of correlation *** One hour after apoptosis induction significant cell fractions were positively stained for ssDNA (33% with MiaPaCa-2 cells, 35% with Hep-G2 cells, 56% with human skin fibroblasts). PARP-cleavage was less sensitive compared to the ssDNA-staining. Apo2.7-expression, Annexin V-binding and TUNEL-reaction were not applicable to detect early apoptosis induced by oxidative stress (below 2 hours), but were efficiently monitoring late apoptosis. Specificity of ssDNA-staining was complete with each cell type even 4 hs after induction of necrosis by the highest sodium azide concentration. In contrast, the same experimental conditions resulted in 50%-90% positively stained necrotic cells by using Apo2.7-expression, TUNEL-reaction or AnnexinV-binding. Surprisingly, specificity of PARP-cleavage was highly depending on the respective cell *** Our study prove that among the five methods investigated only ssDNA-staining allowed to completely differentiate apoptosis from necrosis, and is thus suitable to reliably detect early as well as late apoptosis. Therefore, the ssDNA-stainin

关键词： apoptosis staining method sensitivity specificity oxidative stress adherent cell

Angiogenesis and vascular malformations:Antiangiogenic drugs for treatment of gastrointestinal bleeding

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World Journal of Gastroenterology 2007年第45期13卷 5979-5984页

作者： juergen Bauditz Herbert Lochs Charité University Hospital 4th Department of Medicine Berlin Germany

Treatment of gastrointestinal bleeding in patients with angiodysplasias and Osler’s disease (hereditary hemorrhagic teleangiectasia) is clinically challenging. Frequently, vascular malformations occur as multiple disseminated lesions, making local treatment an unfavorable choice or impossible. After local therapy, lesions often recur at other sites of the intestine. However, as there are few therapeutic alternatives, repeated endoscopic coagulations or surgical resections are still performed to prevent recurrent bleeding. Hormonal therapy has been employed for more than 50 years but has recently been shown to be ineffective. Therefore, new therapeutic strategies are required. Understanding of the pathophysiology of angiogenesis and vascular malformations has recently substantially increased. Currently, multiple inhibitors of angiogenesis are under development for treatment of malignant diseases. Experimental and clinical data suggest that antiangiogenic substances, which were originally developed for treatment of malignant diseases, may also represent long-awaited specif ic drugs for the treatment of vascular malformations. However, antiangiogenics display significantly different actions and side-effects. Although antiangiogenics like thalidomide seem to inhibit gastrointestinal bleeding, other substances like bevacizumab can cause mucosal bleeding. Therefore differential and cautious evaluation of this therapeutic strategy is necessary.

关键词： Angiodysplasias Osler's disease Angio-genesis Gastrointestinal bleeding Vascular endothelialgrowth factor

Typical Refractory Wear Phenomena in Copper Vessels and Novel Monitoring Technologies

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China's Refractories 2021年第2期30卷 16-21页

作者： Dean GREGUREK Katja REINHARTER juergen SCHMIDL Christine WENZL Alfred SPANRING RHI Magnesita Leoben 8700Austria RHI Magnesita Wien 1120Austria

Copper smelting furnaces are typically lined with magnesia-chromite refractories,which are exposed to multiple and complex *** selection of the processing route,furnace type,and slag system is dictated by the specific ore type available;which will determine the individual refractory *** paper evaluates the common refractory wear mechanisms as observed in the copper Peirce-Smith converter and in the copper anode *** chemical factors include corrosion caused by fayalite type slag and sulphur supply,as well as by Cu-oxide *** in the temperature during the furnace operation(thermal shock)create stresses in the brick lining which can only be absorbed to a limited *** factors include erosion,caused primarily by the movement of the metal bath,slag and charging material,as well as stresses in the brickwork due to ***,improper lining procedures can also affect the service *** these wear parameters lead to severe degeneration of the brick microstructure and a decreased lining life,and in the worst case overheated furnace structures and possibly dangerous hot spots or even ***,a detailed investigation and understanding of the wear mechanisms through“post-mortem studies”together with thermochemical calculations by FactSageTM software is an important prerequisite for the refractory *** on these research results,combined with specific process knowledge,appropriate brick lining solutions for copper processing furnaces can be *** addition to the described efforts to investigate refractory wear and optimise lining qualities,it is also essential to monitor the process and the effect on the refractories to further improve both safety and *** this purpose,technologies using sensors and novel digital solutions can be applied.

关键词： wear phenomena copper vessel monitoring technologies

Treatment of nonalcoholic fatty liver disease

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World Journal of Gastroenterology 2006年第14期12卷 2161-2167页

作者： juergen Siebler Peter R Galle Department of Internal Medicine University Hospital of Mainz Langenbeckstr.155131 MainzGermany

Nonalcoholic fatty liver disease （NAFLD） is the most common cause for elevated liver enzymes in the developed nations. Beyond prevention programs which are of particular interest because of the increasing number of overweight children, treatment should be focussed on the most important risk factors, obesity and insulin resistance. As a consequence of elucidating the pathomechanisms of NAFLD, the number of potential therapeutic options increased. However, many studies investigating the therapeutic effect show shortcomings in at least one of the following points： lack of a serial liver biopsy, short term of treatment and limited number of included patients. The second generation insulin sensitizer pioglitazone and rosiglitazone show the most promising improvements in NAFLD, but weight gain and potential hepatotoxidty calls for attention. In conclusion, a general recommendation for the application of specific drugs cannot be given. Besides controlled clinical trials, weight reduction and physical activity to improve insulin sensitivity in obese patients should be the priority objective.

关键词： Nonalcoholic fatty liver disease Treatment

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相图热力学在能源材料中的应用（英文）

中国材料进展 2015年第4期34卷 289-296,316页

作者： Hans juergen Seifert 卡尔斯鲁厄理工学院应用材料物理研究所德国埃根施泰因莱奥波尔茨港76344

CALPHAD结合关键实验可以探究能源材料体系的多元多相反应。介绍了4个基于不同应用背景的合金体系的评估工作:液相烧结的Si C(LPSSi C)体系、转换型锂离子电池体系、掺杂Cr的Ti Al基合金体系以及Zr基热障涂层体系。研究结果显示:CALPHA... 详细信息

CALPHAD结合关键实验可以探究能源材料体系的多元多相反应。介绍了4个基于不同应用背景的合金体系的评估工作:液相烧结的Si C(LPSSi C)体系、转换型锂离子电池体系、掺杂Cr的Ti Al基合金体系以及Zr基热障涂层体系。研究结果显示:CALPHAD热力学计算结果可以用于指导关键实验设计,从而进一步明确研究体系的相图和热力学性质。获得的实验数据又可以作为精炼CALPHAD模型和改进模型参数的输入条件。精炼后的模型参数构成的热力学数据库可用于计算各种相图(包括等温截面、垂直截面、可以用来计算可信的相图(等温截面、垂直截面及波动图)及液相面投影图。

关键词：能源材料 CALPHAD LPSSiC 锂离子电池 TiAl基合金热障涂层

Growth of Large-Area Single- and Bi-Layer Graphene by Controlled Carbon Precipitation on Polycrystalline Ni Surfaces

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Nano Research 2009年第6期2卷 509-516页

作者： Alfonso Reina Stefan Thiele Xiaoting Jia Sreekar Bhaviripudi Mildred S.Dresselhaus juergen A.Schaefer Jing Kong Department of Materials Science and Engineering Massachusetts Institute of TechnologyCambridgeMassachusetts 02139USA Institut für Physik and Institut für Mikro-und Nanotechnologien Technische Universität IlmenauIlmenau 98684Germany Department of Electrical Engineering and Computer Science Massachusetts Institute of TechnologyCambridgeMassachusetts 02139USA Department of Physics Massachusetts Institute of TechnologyCambridgeMassachusetts 02139USA

We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition(CVD).Controlling both the methane concentration during CVD and the substrate cooling rate during graphene growth can signifi cantly improve the thickness *** a result,one-or two-layer graphene regions occupy up to 87%of the fi lm *** layer coverage accounts for 5%11%of the overall fi *** regions expand across multiple grain boundaries of the underlying polycrystalline Ni fi *** number density of sites with multilayer graphene/graphite(>2 layers)is reduced as the cooling rate *** fi lms can also be transferred to other substrates and their sizes are only limited by the sizes of the Ni fi lm and the CVD ***,we demonstrate the formation of fi lms as large as 1 in^(2).These fi ndings represent an important step towards the fabrication of large-scale high-quality graphene samples.

关键词： Graphene chemical vapor deposition nickel catalyst carbon nanomaterials

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焊接数值模拟中以温度为控制变量的高效算法

焊接学报 2009年第8期30卷 77-80页

作者：鄢东洋史清宇吴爱萍 Silvanus juergen 清华大学机械工程系北京100084 EADS Company Innovation Works Munich 81663

对焊接数值模拟中的各种加速计算方法进行了细致研究,并在分段热源法的基础上提出了温度函数法.和分段热源法相比较,温度函数法将焊接数值模拟中的控制变量由热量转变为温度,增加了焊接温度场的可控制性,并提高了模拟温度场在模型宽度... 详细信息

对焊接数值模拟中的各种加速计算方法进行了细致研究,并在分段热源法的基础上提出了温度函数法.和分段热源法相比较,温度函数法将焊接数值模拟中的控制变量由热量转变为温度,增加了焊接温度场的可控制性,并提高了模拟温度场在模型宽度和厚度方向与实际焊接温度场的一致性.文中通过铝合金薄板搅拌摩擦对焊的模型对温度函数法进行验证.结果表明,温度函数法得到的残余应力和变形结果与移动热源方法得到的结果具有一致性,并且和实际试验测量结果吻合,计算效率有大幅度的提高,能够达到工程应用的需要.

关键词：焊接数值模拟快速计算分段热源