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Measuring nanoscale friction at graphene step edges

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Friction 2020年第4期8卷 802-811页

作者： Zhe CHEN seong H.kim Department of Chemical Engineering and Materials Research Institute Pennsylvania State UniversityUniversity ParkPA 16802USA

Although graphene is well known for super-lubricity on its basal plane, friction at its step edge is not well understood and contradictory friction behaviors have been reported. In this study, friction of mono-layer thick graphene step edges was studied using atomic force microscopy (AFM) with a Si tip in dry nitrogen atmosphere. It is found that, when the tip slides over a'buried' graphene step edge, there is a resistive force during the step-up motion and an assistive force during the step-down motion due to the topographic height change. The magnitude of these two forces is small and the same in both step-up and step-down motions. As for the'exposed' graphene step edge, friction increases in magnitude and exhibits more complicated behaviors. During the step-down motion of the tip over the exposed step edge, both resistive and assistive components can be detected in the lateral force signal of AFM if the scan resolution is sufficiently high. The resistive component is attributed to chemical interactions between the functional groups at the tip and step-edge surfaces, and the assistive component is due to the topographic effect, same as the case of buried step edge. If a blunt tip is used, the distinct effects of these two components become more prominent. In the step-up scan direction, the blunt tip appears to have two separate topographic effects–elastic deformation of the contact region at the bottom of the tip due to the substrate height change at the step edge and tilting of the tip while the vertical position of the cantilever (the end of the tip) ascends from the lower terrace to the upper terrace. The high-resolution measurement of friction behaviors at graphene step edges will further enrich understanding of interfacial friction behaviors on graphene-covered surfaces.

关键词： friction graphene step edge atomic force microscopy tip bluntness

Electrochemical Characteristics in Seawater for Cold Thermal Spray-Coated Al-Mg Alloy Layer

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 727-734页

作者： Il-Cho Park seong-Jong kim Division of Marine Engineering Mokpo National Maritime University

For corrosion protection of carbon steel in a marine environment,cold arc thermal spray coating was applied to the surface with Al and Al-Mg alloy *** surface hardness of Al and Al-Mg thermal spray coatings increased with Mg *** the various electrochemical experiments were carried out to evaluate corrosion damage characteristics of the thermal spray coating *** Al and Al-Mg thermal spray coating layers presented negative potentials compared to carbon steel in corrosion potential *** an anodic polarization experiment revealed a tendency of activation polarization with no ***,the corrosion damage of the thermal spray coating layer in galvanostatic experiment was observed mainly at the defect area,and the Al-3Mg thermal spray coating layer presented less surface damages than *** addition,the Al-3Mg thermal spray coating layer showed the lowest corrosion rate while having a sufficient driving voltage for cathodic corrosion ***,it is an optimal thermal spray material for sacrificial anode.

关键词： Corrosion protection Carbon steel Arc thermal spray coating Al-Mg alloy Marine environment

Corrosion characteristics of steel in seawater containing various chloride concentrations generated by electrochemical method

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中国有色金属学会会刊：英文版 2009年第B9期19卷 50-55页

作者： seong-Jong kim Seok-Ki JANG Division of Marine Engineering Mokpo Maritime University

The electro-clean system (ECS), a ballast water management system that eliminates harmful aquatic organisms in ship ballast water via electrochemically produced chloride, was developed. The current density for potentiostatic experiments subjected to seawater with an applied potential (-0.1 V) at various TRC concentrations (2×10-6, 6×10-6, 10×10-6, and 15×10-6) have similar results. The current density at -0.1 V has the highest value compared with that at -0.7 V and -0.4 V. For all concentrations, the current density increases with increasing applied potential.

关键词：含氯化物电化学方法腐蚀特性浓度海水船舶压载水钢铁电流密度

Successful living donor liver transplantation with a graft-to-recipient weight ratio of 0.41 without portal flow modulation:A case report

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World Journal of Clinical Cases 2022年第16期10卷 5414-5419页

作者： seong Hoon kim Center for Liver Cancer National Cancer CenterGoyang 10408GyeonggidoSouth Korea

BACKGROUND There have been numerous efforts to lower the limit of minimum graft size to meet the metabolic demand of recipients in adult-to-adult living donor liver transplantation(LDLT).We experienced a successful case of LDLT using a verysmall-for-size graft without portal flow modulation such as splenectomy or portocaval *** SUMMARY A 49-year-old man(weighing 91 kg)suffering hepatocellular carcinoma accompanied with hepatitis B virus related cirrhosis underwent *** one and only voluntary donor was his 17-year-old daughter whose body weight was 50 kg with a body mass index(BMI)of *** procured right liver graft was 411 g with a real graft-to-recipient weight ratio(GRWR)of 0.41%,the smallest to be reported in the *** the recipient and donor had an uneventful recovery and were discharged on days 15 and 8,respectively,with normal liver *** father and daughter have had no complication so far and are still in good health with normal liver function 81 mo after *** Satisfactory outcomes can be achieved in LDLT with a GRWR as low as 0.41%even without using portal flow modulation in highly selected patients.

关键词： Small-for-size graft Living donor liver transplantation Graft-to-recipient weight ratio Case report

Ultimate strength of single shear bolted connections with cold-formed ferritic stainless steel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第2期14卷 120-136页

作者： Jin-seong LIM Tae-soo kim Seung-hun kim Department of Architectural Engineering Hanbat National UniversityDaejeon 305-719Korea

This paper is focused on the structural behavior of the single shear bolted connections with thin-walled ferritic stainless *** purpose of this study is to investigate the ultimate behaviors,such as ultimate strength and fracture mode of the single shear bolted connections of thin-walled ferritic stainless steel(low cost steel) rather than austenitic stainless steel(high cost steel).Bolt arrangement and end distance parallel to the direction of applied load are considered as main variables of the test specimens for bolted *** have a constant dimension of edge distance perpendicular to the loading direction,bolt diameter,pitch,and gauge.A monotonic tensile test for specimens has been carried out and some bolted connections with long end distance showed curling(out of plane deformation) occurrence which led to strength *** ultimate behaviors such as fracture mode,ultimate strength are compared with those predicted by current design ***,conditions of curling occurrence and the strength reduction due to curling are investigated and modified strength equations are suggested considering the curling effect.

关键词： Cold-formed ferritic stainless steel Bolted connection Bolt arrangement End distance Curling Strength reduction

Boosting overall water splitting by incorporating sulfur into NiFe(oxy)hydroxide

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Journal of Energy Chemistry 2022年第1期31卷 364-371,I0010页

作者： Chiho kim seong Hyun kim Seunghun Lee Ilyeong Kwon seong Hyun kim Shinho kim Changgyu Seok Yoo Sei Park Yangdo kim Department of Materials Science and Engineering Pusan National UniversityBusan 46241Republic of Korea BK21 Four Innovative Graduate Education Program for Global High-tech Materials&PartsPusan National UniversityBusan 46241Republic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH).Pohang 37673Republic of Korea

Developing highly active and cost-effective electrocatalysts for enhancing the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a significant challenge for overall water ***-incorporated nickel iron(oxy)hydroxide(S-NiFeOOH)nanosheets were directly grown on commercial nickel foam using a galvanic corrosion method and a hydrothermal *** incorporation of sulfur into NiFeOOH enhanced the catalytic activity for the HER and OER in 1 M KOH *** enhanced catalytic activity is attributed to the change in the local structure and chemical states due to the incorporation of *** performance for overall water splitting was achieved with an alkaline water *** was realized by employing S-NiFeOOH as a bifunctional electrocatalyst,thereby outperforming a water electrolyzer that requires the usage of precious metal electrocatalysts(i.e.,Pt/C as the HER electrocatalyst and IrO_(2) as the OER electrocatalyst).Moreover,when driven by a commercial silicon solar cell,an alkaline water electrolyzer that uses S-NiFeOOH as a bifunctional electrocatalyst generated hydrogen under natural *** study shows that S-NiFeOOH is a promising candidate for a large-scale industrial implementation of hydrogen production for overall water splitting because of its low cost,high activity,and *** addition,the solar-driven water electrolyzer using S-NiFeOOH as a bifunctional electrocatalyst affords the opportunity for developing effective and feasible solar power systems in the future.

关键词： Overall water splitting Hydrogen production Sulfur incorporated NiFe(oxy)hydroxide Electrocatalysts Solar-driven water splitting

Effects of solution heat treatment on corrosion resistance of 5083F Al alloy

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中国有色金属学会会刊：英文版 2009年第4期19卷 887-891页

作者： seong-Jong kim Seok-Ki JANG Division of Marine Engineering Mokpo Maritime University

Aluminum alloys are used as substitutes for fiber reinforced polymer(FRP) in ships and ***,ships constructed with 5000-series Al alloy suffer a little corrosion in the marine environment,when they run in high speed,and high flow rate,***,solution heat treatment was carried out to prevent *** optimal heat treatment involved heating specimens for 120 min at 420 ℃ and then cooling them in *** addition,the optimal ageing condition involved ageing specimens for 240 min at 180 ℃.The slow strain rate test(SSRT) in a seawater revealed that heat treatment under optimal conditions produced improved elongation,time-to-fracture and amount of dimples compared with the as-received specimen.

关键词：铝合金腐蚀性固溶处理热处理生产纤维增强聚合物电阻慢应变速率海洋环境

Iksan526 Rice Callus Extract Induces Dedifferentiation of Rabbit Articular Chondrocytes via ERK1/2 and PI-3K/Akt Pathways

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Rice science 2020年第6期27卷 504-514页

作者： seong-Hui EO Song Ja kim Department of Biological Sciences College of Natural SciencesKongju National UniversityGongju 32588Republic of Korea

The resveratrol-enriched transgenic rice line Iksan526(IS526),first developed by the Rural Development Administration of Korea using genetic engineering techniques,shows beneficial health effects in mitigating metabolic syndrome and ***,the effects of IS526 on the differentiation of chondrocytes and the underlying mechanism have not been investigated in *** this study,the effects and cellular regulatory mechanisms of IS526 on rabbit articular chondrocytes were *** IS526 callus extract treatment,the expression levels of differentiation-related proteins were detected via western blotting,Alcian blue staining and immune-luorescence ***526 decreased the type Ⅱ collagen and proteoglycan levels in dose-and time-dependent *** further analyzed the effects of IS526 on skeleton genesis in zebrafish larvae using Alcian blue staining,which showed a reduction in cartilage formation along with increased production of matrix metalloproteinase(MMP)-***526 also increased the phosphorylation of ERK1/2 and p38 kinase but inhibited the phosphorylation of *** inhibition of MMP-13 blocked the IS526-induced decrease in type Ⅱ collagen *** of p38 kinase or PI-3K/Akt with SB203580 and LY294002 enhanced the suppression of type Ⅱ collagen,but the blockage of ERK-1/2 by PD98059 rescued IS526-induced *** results suggested that IS526 regulates type Ⅱ collagen and MMP-13 expression via the ERK1/2 and PI-3K/Akt pathways in rabbit articular chondrocytes.

关键词： rice chondrocyte typeⅡcollagen matrix metalloproteinase-13 rice callus extract

Electrophoretic deposition of a supercapacitor electrode of activated carbon onto an indium-tin-oxide substrate using ethyl cellulose as a binder

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Journal of Materials Science & Technology 2020年第23期58卷 188-196页

作者： Taeuk kim seong-Hoon Yi Sang-Eun Chun School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

A transparent energy storage device is an essential component for transparent *** increasing demand for high-power devices stimulates the development of transparent supercapacitors with high power density.A transparent electrode for such supercapacitors can be assembled via the electrophoretic deposition of an active material powder with a binder onto a transparent *** properties of the binder critically influence the electrochemical behavior and performance of the resulting *** cellulose(EC)is known as an eco-friendly,transparent,flexible,and inexpensive ***,we fabricated an electrode film with EC binder via electrophoretic deposition on an indium tin oxide(ITO)substrate instead of using the conventional polytetrafluoroethylene(PTFE)*** assembled electrodes with EC and PTFE were compared to investigate the feasibility of EC as a binder from different perspectives,including homogeneity,wettability,electrochemical behavior,and mechanical *** EC enabled the formation of a homogeneous film composed of smaller particles and with a higher specific capacitance compared with films prepared with *** annealing improved the adhesion strength of the EC because of its glass transition;however,its hydrophobic nature limited utilization of the active material for charge *** electrochemical activation improved the wettability of the electrode,resulting in an increased capacitance of 60 F g^(-1).Furthermore,even with the lower wettability of EC compared with that of PTFE,better rate performance was possible with the EC *** increased mechanical stability after the annealing process ensured an excellent cycle life of 95%capacitance retention for 15,000 cycles.

关键词： Electrophoretic deposition Transparent electrode Activated carbon Ethyl cellulose Indium tin oxide