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Effects of laminar shear stress versus resveratrol on the citrulline-NO cycle in endothelial cells

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Advances in Biological Chemistry 2013年第1期3卷 18-25页

作者： Sue Im Jang yong chool boo Department of Molecular Medicine Cell and Matrix Research Institute BK21 Medical Education Program for Human Resources School of Medicine Kyungpook National University Daegu Korea

Laminar shear stress (LSS) due to pulsatile blood flow enhances endothelial function by multiple mechanisms including NO production. Red wine and its constituent, resveratrol, have also been postulated to provide vascular protective effects. The aim of the present study was to compare the effects of mechanical LSS and pharmacological resveratrol treatments on the endothelial citrulline-NO cycle. Human umbilical vein endothelial cells (HUVECs) were treated with LSS (12 dyn·cm-2) or resveratrol (25 - 100 μM). The expressions of argininosuccinate synthetase 1 (ASS1), argininosuccinate lyase (ASL), nitric oxide synthase 3 (NOS3) and cationic amino acid transporter 1 (CAT1), and the production of NO were determined. The expressions of Kruppel-like factor (KLF) 2 and KLF4 as upstream regulators of ASS1 and NOS3 were also analyzed. LSS strongly increased the mRNA levels of ASS1 (8.3 fold) and NOS3 (5.4 fold) without significant effects on ASL and CAT1 mRNAs. Resveratrol increased the ASS1 mRNA level in a dose-dependent manner up to 3.8 fold at 100 μM. The effects of resveratrol on the expressions of KLF2 and KLF4 mRNAs were smaller than those of LSS. Protein levels of ASS1 and NOS3, and NO production were markedly increased by LSS but resveratrol (50 μM) increased only ASS1 protein level. The results of the current study showed that LSS had greater effects on the citrulline-NO cycle activity leading to NO production, compared to resveratrol. Because resveratrol was not so effective at stimulating the endothelial citrulline-NO cycle, further studies are needed to find more potent drugs that increase the expression of ASS1 and NOS3 genes.

关键词： Citrulline-Nitric Oxide Cycle Endothelial Cells Laminar Shear Stress Resveratrol

Fabrication of SiC_p/AA5083 composite via friction stir welding

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中国有色金属学会会刊：英文版 2012年第S3期22卷 634-638页

作者： Byung-Wook AHN Don-Hyun CHOI yong-Hwan KIM Seung-boo JUNG School of Advanced Materials Science and Engineering Sungkyunkwan University

Microstructure and mechanical properties of SiCp /AA5083 composite fabricated by friction stir welding (FSW) were *** influence of the number of FSW passes on the distribution of SiC particles and mechanical properties in the joint was *** one pass,the SiC particles were entangled in the upper side of the stir zone (SZ).However,the particle distribution became more uniform after two passes due to the repeated stirring of the *** the SiC particles facilitate the grain refinement in the SZ by the pinning effect,the particle including region has much smaller grain size than the SZ without SiC *** SiCp /AA5083 composite region exhibits a Vickers hardness of HV90,which is much higher than the value of HV80 in the SZ produced by FSW without SiC particles.

关键词： metal matrix composite SiC particle friction stir welding mechanical property

Microstructure and mechanical property of A356 based composite by friction stir processing

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Transactions of Nonferrous Metals Society of China 2013年第2期23卷 335-340页

作者： Don-Hyun CHOI yong-Hwan KIM Byung-Wook AHN yong-Il KIM Seung-boo JUNG School of Advanced Materials Science and Engineering Sungkyunkwan University300 Cheoncheon-dong Jangan-gu Suwon Gyeonggi-do 440-746 Korea MEPL Sungkyunkwan University 300 Cheoncheon-dong Jangan-gu Suwon Gyeonggi-do 440-746 Korea

Friction stir processing （FSP） was used to incorporate SiC particles into the matrix of A356 Al alloy to form composite material. Constant tool rotation speed of 1800 r/min and travel speed of 127 mm/min were used in this study. The base metal （BM） shows the hypoeutectic Al-Si dendrite structure. The microstructure of the stir zone （SZ） is very different from that of the BM. The eutectic Si and SiC particles are dispersed homogeneously in primary Al solid solution. The thermo-mechanically affected zone （TMAZ）, where the original microstructure is greatly deformed, is characterized by dispersed eutectic Si and SiC particles aligned along the rotational direction of the tool. The hardness of the SZ shows higher value than that of the BM because some defects are remarkably reduced and the eutectic Si and SiC particles are dispersed over the SZ.

关键词： friction stir processing A356 alloy SiC powder eutectic Si

Comparison of hepatic venous pressure gradient and endoscopic grading of esophageal varices

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World Journal of Gastroenterology 2016年第11期22卷 3212-3219页

作者： Eun Ji Lee yong Jae Kim Dong Erk Goo Seung boo Yang Hyun-Joo Kim Jae Young Jang Soung Won Jeong Department of Radiology Soonchunhyang University Seoul Hospital Department of Radiology Soonchunhyang University Gumi Hospital Department of Gastroenterology Soonchunhyang University Seoul Hospital

AIM: To determine the correlation between the hepatic venous pressure gradient and the endoscopic grade of esophageal ***: From September 2009 to March 2013, a total of 176 measurements of hepatic venous pressure gradient (HVPG) were done in 146 patients. Each transjugular HVPG was measured twice, first using an end whole catheter (EH-HVPG), and then using a balloon catheter (B-HVPG). The HVPG was compared with the endoscopic grade of esophageal varices (according to the general rules for recording endoscopic findings of esophagogastric varices), which was recorded within a month of the measurement of ***: The study included 110 men and 36 women, with a mean age of 56.1 years (range, 43-76 years). The technical success rate of the pressure measurements was 100% and there were no complication related to the procedures. Mean HVPG was 15.3 mmHg as measured using the end hole catheter method and 16.5 mmHg as measured using the balloon catheter method. Mean HVPG (both EH-HVPG and B-HVPG) was not significantly different among patients with different characteristics, including sex and comorbid factors, except for cases with hepatocellular carcinoma (B-HVPG, P = 0.01; EH-HVPG, P = 0.02). Portal hypertension (> 12 mmHg HVPG) occurred in 66% of patients according to EH-HVPG and 83% of patients according to B-HVGP, and significantly correlated with Child’s status (B-HVPG, P < 0.000; EH-HVGP, P < 0.000) and esophageal varies observed upon endoscopy (EH-HVGP, P = 0.003; B-HVGP, P = 0.006). One hundred and thirty-five endoscopies were performed, of which 15 showed normal findings, 27 showed grade 1 endoscopic esophageal varices, 49 showed grade 2 varices, and 44 showed grade 3 varices. When comparing endoscopic esophageal variceal grades and HVPG using univariate analysis, the P value was 0.004 for EH-HVPG and 0.002 for ***: Both EH-HVPG and B-HVPG showed a positive correlation with the endoscopic grade of esophag

关键词： Hepatic venous pressure gradient Liver cirrhosis Esophageal varices Endoscopic grade of esophageal varices Balloon catheter measurement End hole catheter measurement

Hybrid Friction Stir Welding of High-carbon Steel

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Journal of Materials Science & Technology 2011年第2期27卷 127-130页

作者： Don-Hyun Choi Chang-yong Lee Byung-Wook Ahn Jung-Hyun Choi Yun-Mo Yeon Keun Song Seung-Gab Hong Won-Bae Lee Ki-Bong Kang Seung-boo Jung School of Advanced Materials Science and Engineering Sungkyunkwan University 300 Cheoncheon-dongJangan-guSuwonGyeonggi-do 440-746South Korea Department of Mechanical Engineering Korea Advanced Institute of Science and Technology 335 GwahangnoYuseong-guDaejeon 305-701South Korea Department of Advanced Materials Application Suwon Science College 9-10Botong-liJeongnam-myeonHwasungGyeonggi-do 445-742South Korea Technical Research Lab POSCO Corp.Goedong-dongNam-guPohangGyeongbuk790-785South Korea

A high-carbon steel joint,SK5（0.84 wt% C）,was successfully welded by friction stir welding（FSW）,both without and with a gas torch,in order to control the cooling rate during *** welding,the weld zone comprised gray and black regions,corresponding to microstructural variation：a martensite structure and a duplex structure of ferrite and cementite,*** volume fraction of the martensite structure and the Vickers hardness in the welds were decreased with the using of the gas torch,which was related with the lower cooling rate.

关键词： Friction stir welding High-carbon steel Transformation Martensite

Effect of SiC particles on microstructure and mechanical property of friction stir processed AA6061-T4

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中国有色金属学会会刊：英文版 2012年第S3期22卷 614-618页

作者： Don-Hyun CHOI yong-Il KIM DAE-Up KIM Seung-boo JUNG School of Advanced Materials Science and Engineering Sungkyunkwan University MEPL Sungkyunkwan University KITECH 838-11Palbok-dong 2-gaDeokjin-guJeonju-cityJeollabuk-do 561-844Korea

Friction stir processing of AA6061-T4 alloy with SiC particles was successfully carried *** particles were uniformly dispersed into an AA6061-T4 *** SiC particles promoted the grain refinement of the AA6061-T4 matrix by *** mean grain size of the stir zone (SZ) with the SiC particles was obviously smaller than that of the stir zone without the SiC *** microhardness of the SZ with the SiC particles reached about HV80 due to the grain refinement and the distribution of the SiC particles.

关键词： friction stir processing AA6061-T4 SiC particles pinning effect

The Application of Maturity Method on Whitetopping Construction

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Journal of Civil Engineering and Architecture 2011年第3期5卷 233-240页

作者： Jung Jong Suk Park yong boo Jun Myoung Hoon Sohn Jeong Rak Department of Construction Technology Research Senior Research Land ＆ Housing Research Institute Daejeon City 305-731South Korea

The primary objective of this study was to assess the use of the maturity method to determine the joint sawing window and the traffic opening time on whitetopping construction in Korea. To determine joint sawing time, it was necessary to find the minimum strength not to cause raveling and to identify the time to the occurrence of drying shrinkage. This study found that the minimum compressive strength for joint sawing was 4.41MPa （45kg/cm2） and drying shrinkage occurred just after the concrete temperature reached at the peak. To develop the relationship between compressive strength and maturity values, thermachron i-buttons were inserted into the top and mid-depth of the fresh concrete in the test slabs. The results of the laboratory tests indicated that the Arrhenius equation better fitted the relationship between the compressive strength and maturity values than did the Nurse-Saul equation. However, the Nurse-Saul function estimated in-place strength quite well in this study. Therefore, the Nurse-Saul equation was used to determine the joint sawing window and the traffic opening time for whitetopping construction.

关键词： Maturity Nurse-Saul function Arrhenius equation whitetopping

FINITE ELEMENT ANALYSIS OF DDEFORMATION AND RESTORATION FOR CYLINDRICAL BEAM STRUCTURE

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FINITE ELEMENT ANALYSIS OF DDEFORMATION AND RESTORATION FOR ...

第十八届国际反应堆结构力学大会

作者： Myung Hwan boo Chi-yong Park Jin Won Kim Nuclear Mechanical ＆ Material Group KEPRI （Korea Electric Power Research Institute） Nuclear Mechanical ＆ Material Group KEPRI （Korea Electric Power Research Institute） Dept. of Nuclear Engineering Chosun University

＜正＞ 1 INTRODUCTION In plant industry, machine structure or machinery maintains its function by combination or co-relation of many structural parts. When a part of machine structure takes a severe damage by external forces, it can be exchanged by new parts. Before repair working process of the structure, integrity of damaged structure should be evaluated at deformed status. Also, after restoration by suitable work process, repaired structure has to be confirmed safety of structure. In this study, when a part of large size cylindrical structure is plastically deformed by external force, residual stress of structure was evaluated during deformation and restoration process by the finite element analysis.

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氯化胆碱-尿素体系中锌镍合金的电沉积研究

表面技术 2024年第14期53卷 128-138页

作者：孙海静刘爽王贺崔家宁周欣谭勇孙杰沈阳理工大学环境与化学工程学院沈阳110159

目的探究在低共熔溶剂氯化胆碱-尿素(ChCl-Urea DES)体系电沉积Zn-Ni合金的电化学行为、成核机制和耐蚀性。方法通过循环伏安曲线测试(CV)研究了Zn-Ni合金的电化学行为,用计时电流曲线测试(CA)探究了Zn-Ni合金电沉积的形核/生长机制。... 详细信息

目的探究在低共熔溶剂氯化胆碱-尿素(ChCl-Urea DES)体系电沉积Zn-Ni合金的电化学行为、成核机制和耐蚀性。方法通过循环伏安曲线测试(CV)研究了Zn-Ni合金的电化学行为,用计时电流曲线测试(CA)探究了Zn-Ni合金电沉积的形核/生长机制。使用扫描电镜(SEM)对合金镀层表面的微观形貌进行观察,结合能量色散谱仪(EDS)、X-ray衍射(XRD)以及X-ray光电子能谱(XPS)研究镀层的化学成分以及物相的组成,阻抗(EIS)测试和极化测试(Tafel)评估了Zn-Ni合金镀层的抗腐蚀性能。结果Zn-Ni合金在氯化胆碱-尿素的体系中表现出正常的共沉积,与水溶液中的异常共沉积不同。镍的含量高于锌的含量,且Zn-Ni合金的成核方式是三维瞬时成核。从扫描电镜观察的结果来看,当沉积电位从‒0.70 V负向移动时,镍含量有规律地降低,但镍始终高于锌的含量,与循环伏安结果一致。XRD和XPS分析表明,镀层中含有镍,并且确实存在Zn元素。耐蚀性的测试结果表明,在沉积电位为‒0.85 V时,制得的Zn-Ni合金镀层展示出更强的耐腐蚀性。这可能是因为该镀层结构致密,晶粒尺寸小而且在表面均匀分布。结论Zn-Ni合金在ChCl-Urea DES体系下经历扩散控制的不可逆电极过程,呈现正常共沉积,镍的含量高于锌。其成核机制为三维瞬时生长,扩散限制了生长过程。在‒0.85 V的沉积电位下镀得的Zn-Ni合金镀层由于致密性好、晶粒尺寸细小且均匀分布,具备良好的耐腐蚀性。

关键词：低共熔溶剂 ChCl-Urea Zn-Ni合金电沉积成核机制耐蚀性能