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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

Ag-GST/HfO_(x)-based unidirectional threshold switching selector with low leakage current and threshold voltage distribution for high-density cross-point arrays

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Rare Metals 2024年第1期43卷 280-288页

作者： Kyoung-Joung Yoo dae-Yun Kang Nahyun kim Ho-Jin Lee Ta-Hyeong kim Taeho kim Tae Geun kim School of Electrical Engineering Korea UniversitySeoul 02841Republic of Korea

The use of electrochemical-metallization-based volatile threshold switching selectors in cross-point arrays has been widely explored owing to their high on-off ratios and simple ***,these devices are unsuitable for cross-point architectures because of the difficulty in controlling the random filament formation that results in large fluctuations in the threshold voltage during *** this study,we investigated the unidirectional threshold transition characteristics associated with an Ag/GST/HfO_(x)/Pt-based bilayer selector and demonstrated the occurrence of a low leakage current(<1×10^(-11) A) and low distribution of the threshold voltage(Δ0.11 V).The bilayer structure could control the filament formation in the intermediate state through the insertion of an HfO_(x) tunneling *** stacking a bilayer selector with NiO_(x)based resistive random-access memory,the leakage and programming currents of the device could be significantly *** the crossbar array configuration,we performed equivalent circuit analysis of a one-selector oneresistor(1S1R) devices and estimated the optimal array size to demonstrate the applicability of the proposed *** maximum acceptable crossbar array size of the 1S1R device with the Ag/GST/HfO_(x)/Pt/Ti/NiO_(x)/Pt structure was 5.29×10^(14)(N^(2),N=2.3×10^(7)).

关键词： Selector device Tunneling barrier Threshold switching Sputtering 1S1R Cross-point array

Dual in-situ observation of tribochemical and morphological evolution of single-layer WS_(2)and multi-layer WS_(2)/C coatings

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Friction 2024年第7期12卷 1580-1598页

作者： Yuzhen LIU Jae-Ho HAN Shusheng XU Young Chan JUNG dae-Eun kim State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Department of Mechanical Engineering Yonsei UniversitySeoul03722Republic of Korea Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai Yantai 264000China Yantai Zhongke Research Institute of Advanced Materials and Green Chemical Engineering Yantai 264000China

The outstanding tribological performance of transition metal dichalcogenides(TMDs)is attributed to their unique sandwich microstructure and low interlayer shear *** advantageous structure allows TMDs to demonstrate exceptional friction reduction ***,the incorporation of TMDs and amorphous carbon(a-C)in multi-layer structures shows excellent potential for further enhancing tribological and anti-oxidation *** carbon,known for its high ductility,chemical inertness,and excellent wear resistance,significantly contributes to the overall performance of these multi-layer *** gain an in-depth understanding of the tribological mechanism and evolution of TMDs’multi-layer coatings,a dual in-situ analysis was carried out using a tribometer equipped with a 3D laser microscope and a Raman *** innovative approach allowed for a comprehensive evolution of the tribological,topographical,and tribochemical characteristics of both single-layer WS_(2)and multi-layer WS_(2)/C coatings in real *** findings from the dual in-situ tribotest revealed distinct failure characteristics between the single-layer WS_(2)coating and the multi-layer WS_(2)/C *** single-layer WS_(2)coating predominantly experienced failure due to mechanical removal,whereas a combination of mechanical removal and tribochemistry primarily influenced the failure of the multi-layer WS_(2)/C *** tribological evolution process of these two coatings can be classified into four stages on the basis of their tribological behavior:the running-in stage,stable friction stage,re-deposition stage,and lubrication failure *** stage represents a distinct phase in the tribological behavior of the coatings and contributes to our understanding of their behavior during sliding.

关键词： In-situ analysis multi-layer coating tribology tribochemistry

Vertical plane depth-resolved surface potential and carrier separation characteristics in flexible CZTSSe solar cells with over 12% efficiency

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Carbon Energy 2024年第3期6卷 36-52页

作者： dae-Ho Son Ha Kyung Park dae-Hwan kim Jin-Kyu Kang Shi-Joon Sung dae-Kue Hwang Jaebaek Lee Dong-Hwan Jeon Yunae Cho William Jo Taeseon Lee JunHo kim Sang-Hoon Nam Kee-Jeong Yang Division of Energy Technology DGISTDaeguRepublic of Korea Research Center for Thin Film Solar Cells DGISTDaeguRepublic of Korea Department of Physics Ewha Womans UniversitySeoulRepublic of Korea Department of Physics Incheon National UniversityIncheonRepublic of Korea Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMassachusettsUSA

Cu2ZnSn(S,Se)4(CZTSSe)solar cells have resource distribution and economic *** main cause of their low efficiency is carrier loss resulting from recombination of photo-generated electron and *** overcome this,it is important to understand their electron-hole behavior *** determine the carrier separation characteristics,we measured the surface potential and the local current in terms of the absorber *** elemental variation in the intragrains(IGs)and at the grain boundaries(GBs)caused a band edge shift and bandgap(Eg)*** the absorber surface and subsurface,an upward Ec and Ev band bending structure was observed at the GBs,and the carrier separation was *** the absorber center,both upward Ec and Ev and downward Ec-upward Ev band bending structures were observed at the GBs,and the carrier separation was *** improve the carrier separation and suppress carrier recombination,an upward Ec and Ev band bending structure at the GBs is desirable.

关键词： carrier separation CZTSSe flexible solar cell local current surface potential

N, P co-doped 3D porous carbon with self-assembled morphological control via template-free method for potassiumion battery anodes

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Rare Metals 2024年第9期43卷 4243-4252页

作者： Jeehoon Yu dae Kyom kim Hong Geun Oh Seung-Keun Park Youngjae Yoo Department of Advanced Materials Engineering Chung-Ang University

The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries （PIBs）,resulting in comparatively poor rate performance and cycle ***,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous *** as-prepared N,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without *** obtained electrode N3P1 exhibits a reversible specific capacity of 258 m Ah·g-1at a current density of 0.1A·g-1and a good long-term cycle performance (96.1%capacity retention after 800 cycles at 0.5 A·g-1).Kinetic investigations show that the N3P1 electrode with the welldeveloped porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by N and P ***-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural stability and reversibility owing to the expanded interlayer *** suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy storage materials.

关键词： 3D porous structures Amorphous carbons Nitrogen and phosphorous co-doping Potassium-ion batteries

Benefit in physical function and quality of life to nonsurgical treatment of varicose veins: Pilot study

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World Journal of Clinical Cases 2024年第3期12卷 517-524页

作者： Gwon-Min kim BoKun kim Minwoo Jang Jong-Hwan Park Miju Bae Chung Won Lee Jong Won kim up Huh Medical Research Institute Pusan National University School of MedicineYangsan 50612South Korea Future Convergence Research Institute Changwon National UniversityChangwon 51140South Korea Department of Convergence Medical Science School of MedicinePusan National UniversityYangsan 50612South Korea Health Convergence Medicine Laboratory Biomedical Research InstitutePusan National University HospitalBusan 49241South Korea Department of Thoracic and Cardiovascular Surgery Pusan National University School of MedicineBiomedical Research InstitutePusan National University HospitalBusan 49241South Korea

BACKGROUND Studies on varicose veins have focused its effects on physical function;however,whether nonsurgical treatments alter muscle oxygenation or physical function remains ***,the differences in such functions between individuals with varicose veins and healthy individuals remain *** To investigate changes in physical function and the quality of life(QOL)following nonsurgical treatment of patients with varicose veins and determine the changes in their muscle oxygenation during *** We enrolled 37 participants(those with varicose veins,n=17;healthy individuals,n=20).We performed the following measurements pre-and post-nonsurgical treatment in the varicose vein patients and healthy individuals:Calf muscle oxygenation during the two-minute step test,open eyes one-leg stance,30 s sit-to-stand test,visual analog scale(VAS)for pain,Pittsburgh sleep quality index,physical activity assessment,and QOL *** Varicose veins patients and healthy individuals differ in most variables(physical function,sleep quality,and QOL).Varicose veins patients showed significant differences between pre-and post-nonsurgical treatment—results in the 30 sit-to-stand test[14.41(2.45)to 16.35(4.11),P=0.018],two-minute step test[162.29(25.98)to 170.65(23.80),P=0.037],VAS for pain[5.35(1.90)to 3.88(1.73),P=0.004],and QOL[39.34(19.98)to 26.69(17.02),P=0.005];however,no significant difference was observed for muscle *** Nonsurgical treatment improved lower extremity function and QOL in varicose veins patients,bringing their condition close to that of healthy *** studies should include patients with severe varicose veins requiring surgery to confirm our findings.

关键词： Varicose vein Nonsurgical treatment Physical function Quality of life Near infrared spectroscopy

Development of immature ovarian teratoma after mature teratoma in a girl with familial ovarian teratoma:A case report

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World Journal of Clinical Cases 2024年第8期12卷 1442-1447页

作者： U Chul Ju Woo dae Kang Seok Mo kim Department of Obstetrics and Gynecology Chonnam National University Medical SchoolGwangju 61469South Korea

BACKGROUND Immature ovarian teratoma is a rare and aggressive neoplasm that affects young *** report is the first to describe the development of immature teratoma after ovarian cystectomy for mature teratoma of the ovary in an adolescent female with a family history of ovarian *** SUMMARY A 16-year-old girl who had undergone bilateral ovarian cystectomy for mature teratomas 3 years ago showed bilateral adnexal tumors during her regular ultrasonography follow-up every 6 *** received laparoscopic bilateral ovarian cystectomy,and final histopathology showed grade-1 immature teratoma of the left ovary and mature teratoma of the right *** left salpingo-oophorectomy and staging procedures were performed *** mother,maternal aunt,and maternal grandmother had also received surgeries for mature ovarian *** It is important to have guidance on management of patient and family members with familial ovarian teratomas.

关键词： Familial ovarian teratomas Adolescent female Immature ovarian teratoma Management Case report

Low temperature-mediated repression and far-red light-mediated induction determine morning FLOWERING LOCUS T expression levels

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Journal of Integrative Plant Biology 2024年第1期66卷 103-120页

作者： Hayeon kim Hye Won Kang dae Yeon Hwang Nayoung Lee Akane Kubota Takato Imaizumi Young Hun Song Department of Agricultural Biotechnology Seoul National UniversitySeoul 08826Korea Department of Biology Ajou UniversitySuwon 16499Korea Plant Genomics and Breeding Institute Seoul National UniversitySeoul 08826Korea Graduate School of Science and Technology Nara Institute of Science and TechnologyIkomaNara 630‐0192Japan Department of Biology University of WashingtonSeattleWA 98195USA Institute of Agricultural Life Sciences Seoul National UniversitySeoul 08826Korea

In order to flower in the appropriate season,plants monitor light and temperature changes and alter downstream pathways that regulate florigen genes such as Arabidopsis(Arabidopsis thaliana)FLOWERING LOCUS T(FT).In Arabidopsis,FT messenger RNA levels peak in the morning and evening under natural long-day conditions(LDs).However,the regulatory mechanisms governing morning FT induction remain poorly *** morning FT peak is absent in typical laboratory LDs characterized by high red:far-red light(R:FR)ratios and constant ***,we demonstrate that ZEITLupE(ZTL)interacts with the FT repressors TARGET OF EATs(TOEs),thereby repressing morning FT expression in natural *** LDs with simulated sunlight(R:FR=1.0)and daily temperature cycles,which are natural LD-mimicking environmental conditions,FT transcript levels in the ztl mutant were high specifically in the morning,a pattern that was mirrored in the toe1 toe2 double *** night-to-morning temperatures increased the inhibitory effect of ZTL on morning FT expression by increasing ZTL protein levels early in the ***-red light counteracted ZTL activity by decreasing its abundance(possibly via phytochrome A(phyA))while increasing GIGANTEA(GI)levels and negatively affecting the formation of the ZTL-GI complex in the ***,the phyA-mediated high-irradiance response and GI play pivotal roles in morning FT *** findings suggest that the delicate balance between low temperature-mediated ZTL activity and the far-red light-mediated functions of phyA and GI offers plants flexibility in fine-tuning their flowering time by controlling FT expression in the morning.

关键词： far-red light FLOWERING LOCUS T flowering time GIGANTEA low night-to-morning temperature natural long days phytochrome A red to far-red ratio ZEITLupE

Anode surface engineering of zinc-ion batteries using tellurium nanobelt as a protective layer for enhancing energy storage performance

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Journal of Energy Chemistry 2024年第5期92卷 113-123页

作者： Soobeom Lee Yeonjin Je Boeun Seok Hyun Tae kim Yong-Ryun Jo Soong Ju Oh Byoungyong Im dae Guen kim Sang-Soo Chee Geon-Hyoung An Department of Energy System Engineering Gyeongsang National UniversityJinju 52725Republic of Korea Nano Convergence Materials Center Korea Institute of Ceramic Engineering and Technology(KICET)Jinju 52851Republic of Korea Department of Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea School of Materials Science and Engineering Gyeongsang National UniversityJinju 52828Republic of Korea GIST Advanced Insitute of Instrumental Analysis(GAIA) Electron Microscopy LaboratoryGwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Center for Advanced Materials and Processing Institute for Advanced EngineeringYongin 17180Republic of Korea Department of Energy Engineering Gyeongsang National UniversityJinju 52725Republic of Korea

Over the years,zinc-ion batteries(ZIBs)have attracted attention as a promising next-generation energy storage technology because of their excellent safety,long cycling performance,eco-friendliness,and high-power ***,issues,such as the corrosion and dissolution of the Zn anode,limited wet-tability,and lack of sufficient nucleation sites for Zn plating,have limited their practical *** introduction of a protective layer comprising of tellurium(Te)nanobelts onto the surface of Zn anode has emerged as a promising approach to overcome these limitations and improve the electrochemical behav-ior by enhancing the safety and wettability of ZIBs,as well as providing numerous nucleation sites for Zn *** the presence of a Te-based protective layer,the energy power density of the surface-engineered Zn anode improved significantly(ranging from 310 to 144 W h kg^(-1),over a power density range of 270 to 1,800 W kg^(-1)),and the lifespan capability was *** results demonstrate that the proposed strategy of employing Te nanobelts as a protective layer holds great promise for enhancing the energy storage performance of zIBs,making them even more attractive as a viable energy storage solution forthefuture.

关键词： Zn ion battery Anode Protective layer Tellurium Nanobelt