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Mechanical strength and corrosion resistance of Al-additive friction stir welded AZ31B joints

Journal of Magnesium and Alloys 2023年第5期11卷 1519-1535页

作者： Jae-Yeon kim Eun-Woo kim Dong-O kim Eun-Kyo ju Ji-Eun Lee Jaeheon Lee Jai-Won Byeon Mining Engineering Department Colorado School of MinesGoldenCO 80401USA Department of Materials Science and Engineering Seoul National University of Science and TechnologySeoul 01811Republic of Korea

Compared to other structural alloys,magnesium alloys have a relatively poor corrosion resistance and low mechanical strength,which can be further deteriorated when these alloys are subjected to joining processes using the existing joining ***,we propose for the first time an additive friction stir-welding(AFSW)using fine Al powder as an additive to improve the mechanical strength as well as corrosion resistance of AZ31B weld *** is a solid-state welding method of forming a high-Al AZ31B joint via an in-situ reaction between pure Al powders filled in a machined groove and the AZ31B *** optimize the process parameters,AFSW was performed under different rotational and transverse speeds,and number of passes,using tools with a square or screw *** particular,to fabricate a weld zone,where the Al was homogenously dispersed,the effects of the groove shape were investigated using three types of grooves:surface one-line groove,surface-symmetric grooves,and inserted symmetric *** homogenous and defect-less AFS-welded AZ31B joint was successfully fabricated with the following optimal parameters:1400 rpm,25 mm/min,four passes,inserted symmetric grooves,and the tool with a square *** AFSW fully dissolved the additive Al intoα-Mg and in-situ precipitated Mg_(17)Al_(12)particles,which was confirmed via scanning electron microscopy,transmission electron microscope,and X-ray diffraction *** microhardness,joint efficiency,and elongation at the fracture point of the AFS-welded AZ31B joint were 80 HV,101%,and 8.9%,*** values are higher than those obtained for the FS-welded AZ31 joint in previous *** corrosion resistance of the AFS-welded AZ31B joint,evaluated via hydrogen evolution measurements and potentiodynamic polarization tests,was enhanced to 55%relative to the FS-welded AZ31B joint.

关键词： AZ31B magnesium alloy Additive friction stir-welding In-situ reaction Mg_(17)Al_(12)particles Joint efficiency Corrosion resistance

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Flexible and disposable paper-based gas sensor using reduced graphene oxide/chitosan composite

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Journal of Materials Science & Technology 2022年第6期101卷 165-172页

作者： Hyunjun Park woong kim Sang Won Lee Joohyung Park Gyudo Lee Dae Sung Yoon Wonseok Lee Jinsung Park Department of Control and Instrumentation Engineering Korea UniversitySejong 30019Republic of Korea School of Biomedical Engineering Korea UniversitySeoul 02841Republic of Korea Department of Biotechnology and Bioinformatics Korea UniversitySejong 30019Republic of Korea Department of Electrical Engineering Korea National University of TransportationChungju 27469Republic of Korea

Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by *** is related to various respiratory diseases such as pneumonia and sudden infant death ***,because the toxicity of nitrogen dioxide is high in overpopulated areas(i.e.,a capital or metropolis),the development of simple,practical,and facile sensors is highly *** work presents a flexible and disposable paper-based NO_(2)sensor based on a reduced graphene oxide/chitosan(r GO/CS)*** synthesized r GO/CS composite can be easily flexed and deformed into various shapes,which are attributed to chitosan molecules that function as a dispersion and reduction agent and support *** addition,this composite can be attached to paper owing to its adhesive property;hence it can be utilized in versatile applications in a disposable *** analyzing the conductive change of the r GO/CS composite when it reacts with NO_(2),we can detect nitrogen dioxide in a concentration range of 0–100 ppm with a detection limit of 1 ***,we performed NO_(2)detection in the exhaust gas released by automobiles using the r GO/CS composite for practical *** results indicated that the r GO/CS composite has the potential to be used in feasible gas sensing as a facile and disposable sensor under various conditions.

关键词： Reduced graphene oxide Chitosan Composite material Nitrogen dioxide Paper-based gas sensor Flexible and disposable sensor

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Alleviating Interfacial Recombination of Heterojunction Electron Transport Layer via Oxygen Vacancy Engineering for Efficient Perovskite Solar Cells Over 23%

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Energy & Environmental Materials 2023年第2期6卷 311-322页

作者： Yohan Ko Taemin kim Chanyong Lee Changhyun Lee Yong ju Yun Yongseok jun Graduate School of Energy and Environment(KU-KIST Green School) Korea UniversitySeoul 02841Korea

Electron transport layer(ETL)is pivotal to charge carrier transport for PSCs to reach the Shockley-Queisser *** study provides a fundamental understanding of heterojunction electron transport layers(ETLs)at the atomic level for stable and efficient perovskite solar cells(PSCs).The bilayer structure of an ETL composed of SnO_(2) on TiO_(2) was examined,revealing a critical factor limiting its potential to obtain efficient *** of oxygen vacancies in the TiO_(2) underlayer via an annealing process is found to induce manipulated band offsets at the interface between the TiO_(2) and SnO_(2) ***-depth electronic investigations of the bilayer structure elucidate the importance of the electronic properties at the interface between the TiO_(2) and SnO_(2) *** apparent correlation in hysteresis phenomena,including current density-voltage(J-V)curves,appears as a function of the type of band *** functional theory calculations reveal the intimate relationship between oxygen vacancies,deep trap states,and charge transport efficiency at the interface between the TiO_(2) and SnO_(2) *** formation of cascade band alignment via control over the TiO_(2) underlayer enhances device performance and suppresses *** performance exhibits a power conversion efficiency(PCE)of 23.45%with an open-circuit voltage(V_(oc))of 1.184 V,showing better device stability under maximum power point tracking compared with a staggered bilayer under one-sun continuous illumination.

关键词： electron transport bilayer heterojunction bilayers interfacial defect oxygen vacancy engineering perovskite solar cells

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Rare case of hepatocellular carcinoma metastasis to urinary bladder:A case report

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World Journal of Clinical Cases 2022年第16期10卷 5470-5478页

作者： Yohan kim Young Seok kim Jeong-ju Yoo Sang Gyune kim Susie Chin Ahrim Moon Department of Gastroenterology Soonchunhyang University Hospital BucheonBucheon B14200202Gyeonggi-doSouth Korea Division of Gastroenterology and Hepatology Department of Internal MedicineSoonchunhyang University Bucheon HospitalBucheon B14200202Gyeonggi-doSouth Korea Department of Pathology Soonchunhyang University Bucheon HospitalBucheon B14200202Gyeonggi-doSouth Korea Department of Pathology Soonchunhyang University Bucheon HospitalSoonchunhyang University College of MedicineBucheon B14200202Gyeonggi-doSouth Korea

BACKGROUND Hepatocellular carcinoma(HCC)is a primary liver cancer with high prevalence and *** are many cases of advanced HCC at the time of *** methods and prognosis are different depends on whether metastasis is ***,it is necessary to make an accurate evaluation at the time of *** metastases of HCC usually occur through hematogenous spread or through adjacent organs such as the *** to the urinary bladder alone is ***,we report a rare case of biopsy-proven solitary metastasis of HCC to the bladder in a 60-year-old *** SUMMARY A 60-year-old female patient was found to be positive for hepatitis B surface antigen by chance after abdominal ultrasonography showed abnormal ***,liver dynamic computed tomography(CT)was *** patient visited the hospital for further *** and CT showed 3.6 cm sized arterial enhancing mass in segment 5 and an infiltrative mass in segment *** patient was diagnosed with HCC through liver dynamic magnetic resonance imaging and liver ***,she underwent two transcatheter arterial chemoembolizations within five months for *** follow-up,a newly appeared bladder tumor was found on liver dynamic *** underwent transurethral resection of the bladder tumor for diagnosis and *** tissue was confirmed as metastatic *** Although rare,metastasis to urinary bladder from HCC can occur without evidence of other distant ***,regular follow-up imaging examination and clinical attention are required.

关键词： Hepatocellular carcinoma Metastasis Urinary bladder Case report

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Comparison Study and Forensic Analysis between Experiment and Coupled Dynamics Simulation for Submerged Floating Tunnel Segment with Free Ends under Wave Excitations

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Computer Modeling in Engineering & Sciences 2023年第10期137卷 155-174页

作者： Woo Chul Chung Chungkuk Jin Moo Hyun kim ju-young Hwang Division of Mechanical Engineering Korea Maritime&Ocean UniversityBusanSouth Korea Department of Ocean Engineering and Marine Sciences Florida Institute of TechnologyMelbourneFLUSA Department of Ocean Engineering Texas A&M UniversityCollege StationTXUSA Department of Civil Engineering Dong-Eui UniversityBusanSouth Korea

This paper presents dynamic-behavior comparisons and related forensic analyses of a submerged floating tunnel(SFT)between numerical simulation and physical experiment under regular and irregular *** experiments are conducted in the 3Dwave tank with 1:33.3 scale,and the corresponding coupled time-domain simulation tool is devised for *** entire SFT systemconsists of a long concrete tunnel and 12 tubular aluminummooring *** numerical simulation models,the Cummins equation with 3D potential theory including second-order wave-body interaction effects and the much simpler Morison-equation-based formula with the lumped-massbased line model,are designed and *** analyses for mooring-line adjustments in the simulation are carried out in view of the best representation of the physical *** that,the measured pre-tension distribution and systemstiffness of twelvemooring lines arewell reproduced in the ***,the dynamic responses and mooring tensions of the SFT are compared under regular and irregular *** measured and simulated results coincide reasonably well for both regular-and irregular-wave conditions.

关键词： Submerged floating tunnel comparative study forensic analysis mooring-line modeling dynamic response mooring tension

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CopE and TLR6 RNAi-mediated tomato resistance to western flower thrips

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Journal of Integrative Agriculture 2023年第2期22卷 471-480页

作者： Jelli VENKATESH Sung Jin kim Muhammad Irfan SIDDIQUE ju Hyeon kim Si Hyeock LEE Byoung-Cheorl KANG Department of Agriculture Forestry and BioresourcesResearch Institute of Agriculture and Life SciencesPlant Genomics Breeding InstituteCollege of Agriculture and Life SciencesSeoul National UniversitySeoul 08826Republic of Korea Department of Agricultural Biotechnology Seoul National UniversitySeoul 08826Republic of Korea Vegetable Research Division National Institute of Horticulture and Herbal ScienceRural Development AdministrationJeonju 55365Republic of Korea Research Institute of Agriculture and Life Sciences Seoul National UniversitySeoul 08826Republic of Korea

The western flower thrips(WFT;Frankliniella occidentalis)is a mesophyll cell feeder that damages many *** of WFT is complex due to factors such as high fecundity,short reproduction time,ability to feed on a broad range of host plants,and broad pesticide *** challenges have driven research into developing alternative pest control approaches for *** study analyzed the feasibility of a biological control-based strategy to manage WFT using RNA interference(RNAi)-mediated silencing of WFT endogenous *** the delivery of RNAi,we developed transgenic tomato lines expressing double-stranded RNA(dsRNA)of coatomer protein subunit epsilon(CopE)and Toll-like receptor 6(TLR6)from *** genes are involved in critical biological processes of WFT,and their dsRNA can be lethal to these insects when ingested *** WFT that fed on the transgenic dsRNAexpressing tomato flower stalk showed increased mortality compared with insects that fed on wild-type *** addition,WFT that fed on TLR6 and CopE transgenic tomato RNAi lines showed reduced levels of endogenous CopE and TLR6 transcripts,suggesting that their mortality was likely due to RNAi-mediated silencing of these ***,our findings demonstrate that transgenic tomato plants expressing dsRNA of TLR6 and CopE can be lethal to ***,suggesting that these genes may be deployed to control insecticide-resistant WFT.

关键词： coatomer protein subunit epsilon(CopE) Frankliniella occidentalis insect resistance RNA interference Toll-like receptor 6(TLR6) tomato transgenics

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Sperm hyaluronidase is critical to mammals'fertilization for its ability to disperse cumulus-oocyte complex layer

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Asian Journal of Andrology 2022年第4期24卷 411-415页

作者： Dong-Won Seol Sang Hoon Joo Young-Hyun kim Bong-Seok Song Bo-woong Sim Sun-Uk kim Soojin Park Gabbine Wee Ekyune kim Laboratory Animal Center Daegu-Gyeongbuk Medical Innovation Foundation(DGMIF)Daegu 41061Korea College of Pharmacy Catholic University of DaeguGyeongbuk 38430Korea National Primate Research Center(NPCR) Korea Research Institute of Bioscience and BiotechnologyChungcheongbuk-do 28116Korea Futuristic Animal Resource and Research Center Korea Research Institute of Bioscience and BiotechnologyChungcheongbuk-do 28116Korea Department of Biochemistry and Molecular Biology Melvin and Bren Simon Comprehensive Cancer CenterIndiana University School of MedicineIndianapolisIN 46202USA

Glycosylphosphatidylinositol-anchored sperm hyaluronidases have long been believed to assist in sperm penetration through the cumulus-oocyte complex(COC);however,their role in mammalian fertilization remains ***,we have shown that hyaluronidase 5(Hyal5)/Hyal7 double-knockout(dKO)mice produce significantly fewer offspring than their wild-type(WT)counterparts because of defective COC *** infertility is mainly caused by a low sperm *** can be further exacerbated by the deficiency of sperm hyaluronidase,which disperses the cumulus cells of the outer layer of the *** the current study,we evaluated the effects of a low count of Hyal-deficient sperm and conditions of ovulated oocytes on the fertilization rate using a mouse *** results demonstrated that a low sperm count further decreases the in vitro fertilization(IVF)rate of Hyal-deficient dKO *** addition,the dKO spermatozoa resulted in a fertilization rate of 12.5%upon fertilizing COCs with a thick cumulus layer,whereas the IVF rate was comparable to that of WT spermatozoa when oocytes with a thin or no cumulus layer were ***,we proved that the IVF rate of dKO spermatozoa could be recovered by adding rat spermatozoa as a source of sperm *** results suggest that a deficiency of proteins involved in fertilization,such as sperm hyal,has a vital role in fertilization.

关键词： HYAL5 HYAL7 cumulus-oocyte complex fertilization infertility sperm hyaluronidase

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Engineered NiCo-LDH nanosheets- and ZnFe_(2)O_(4) nanocubes-decorated carbon nanofiber bonded mats for high-rate asymmetric supercapacitors

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Green Energy & Environment 2022年第6期7卷 1228-1240页

作者： Jae-Gyoung Seong Tae Hoon Ko Danyun Lei woong-Ki Choi Yun-Su Kuk Min-Kang Seo Byoung-Suhk kim Department of Organic Materials&Fiber Engineering Jeonbuk National University567 Baekje-daeroDeokjin-guJeonju-siJeollabuk-do54896Republic of Korea Department of BIN Convergency Technology Jeonbuk National University567 Baekje-daeroDeokjin-guJeonju-siJeollabuk-do54896Republic of Korea Korea Institute of Carbon Convergence Technology Jeonju54852Republic of Korea Department of Environmental Biology and Water Engineering College of Urban ConstructionWuchang Shouyi UniversityWuhan430064China

In this work,we have prepared the hierarchically nanostructured core–shell NiCo layered double hydroxide(NiCo-LDH)nanosheets-and ZnFe_(2)O_(4) nanocubes-decorated polyacrylonitrile(PAN)/pitch-based carbon nanofibers(PPCNs)webs(NiCo-LDH@PPCNs as cathode and ZnFe_(2)O_(4)@PPCNs as anode materials)with the bonded network structure by a facile and scalable hydrothemal ***,the low-cost pitch with lower softening point(~90℃)as co-precursor was utilized to produce the PAN/pitch-based carbon nanofibers(PPCNs)with enhanced electrical *** obtained PPCNs with pitch content of 30%(PP30CNs)electrode material delivered higher specific capacitance(~67 F g^(-1))than that(~48 F g^(-1))of the PAN-based carbon nanofibers(PCNs)at 1 A g^(-1),due to the increased electrical conductivity and lower interfacial charge transfer resistance(RCT)of~0.16 ***,the NiCo-LDH-decorated PP30CNs(NiCoLDH@PP30CNs)as cathode material showed superior specific capacitance of 1162 F g^(-1) at 1.0 A g^(-1) and ultra-high retention rate of 91.56%at 10 A g^(-1).The ZnFe_(2)O_(4)@PP30CNs as anode material also showed higher specific capacitance of 282 F g^(-1) at 1 A g^(-1) and good rate capability with capacitance retention of 56.73%at 10 A g^(-1).The as-fabricated asymmetric NiCo-LDH@PP30CNs//ZnFe_(2)O_(4)@PP30CNs hybrid supercapacitor device delivered a specific capacitance of~98 F g^(-1) at 1 A g^(-1) and excellent capacitance retention of~88%after 5000 charge–discharge cycles.

关键词： Carbon nanofiber Pitch Asymmetric Rate capability Supercapacitor

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Effect of solid-solution strengthening on deformation mechanisms and strain hardening in medium-entropy V_(1-x)Cr_(x)CoNi alloys

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Journal of Materials Science & Technology 2022年第13期108卷 270-280页

作者： Hyun Chung Dae woong kim Woo Jin Cho Heung Nam Han Yuji Ikeda Shoji Ishibashi Fritz Körmann Seok Su Sohn Department of Materials Science and Engineering Korea UniversitySeoul 02841South Korea Center for High Entropy Alloys Pohang University of Science and TechnologyPohang 37673South Korea Department of Materials Science and Engineering and Research Institute of Advanced Materials Seoul National UniversitySeoul 08826South Korea Institute for Materials Science University of StuttgartPfaffenwaldring 55Stuttgart 70569Germany Computational Materials Design Max-Planck-Institut für Eisenforschung GmbHMax-Planck-Strabe 1Düsseldorf 40237Germany Research Center for Computational Design of Advanced Functional Materials(CD-Fmat) National Institute of Advanced Industrial Science and Technology(AIST)TsukubaIbaraki 305-8568Japan Department of Materials Science and Engineering Delft University of TechnologyMekelweg2Delft 2628 CDthe Netherlands

High-and medium-entropy alloys(HEAs and MEAs)possess high solid-solution *** investigations have been conducted on its impact on yield strength,however,there are limited reports regarding the relation between solid-solution strengthening and strain-hardening *** addition,no attempt has been made to account for the dislocation-mediated plasticity;most works focused on twinning-or transformation-induced plasticity(TWIP or TRIP).In this work we reveal the role of solidsolution strengthening on the strain-hardening rate via systematically investigating evolutions of deformation structures by controlling the Cr/V ratio in prototypical V_(1-x)Cr_(x)CoNi *** the TWIP of CrCoNi with the dislocation slip of V_(0.4)Cr_(0.6)CoNi,the hardening rate of CrCoNi was superior to slip-band refinements of V_(0.4)Cr_(0.6)CoNi due to the dynamic Hall-Petch ***,as V content increased further to V_(0.7)Cr_(0.3)CoNi and VCoNi,their rate of slip-band refinement in V_(0.7)Cr_(0.3)CoNi and VCoNi with high solid-solution strength surpassed that of *** it is generally accepted in conventional alloys that deformation twinning results in a higher strain-hardening rate than dislocation-mediated plasticity,we observed that the latter can be predominant in the former under an activated huge solid-solution strengthening *** high solid-solution strength lowered the cross-slip activation and consequently retarded the dislocation rearrangement rate,i.e.,the dynamic *** delay in the hardening rate decrease,therefore,increased the strain-hardening rate,results in an overall higher strain-hardening rate of V-rich alloys.

关键词： Medium-entropy alloy Tensile property Solid-solution strength Strain-hardening rate Stacking fault energy

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Absolute dominance of hydrogenotrophic methanogens in full-scale anaerobic sewage sludge digesters

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Journal of Environmental Sciences 2013年第11期25卷 2272-2280页

作者： Jaai kim woong kim Changsoo Lee School of Urban and Environmental Engineering Ulsan National Institute of Science and Technology Department of Chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology

Anaerobic digestion （AD） is gaining increasing attention due to the ability to covert organic pollutants into energy-rich biogas and, accordingly, growing interest is paid to the microbial ecology of AD systems. Despite extensive efforts, AD microbial ecology is still limitedly understood, especially due to the lack of quantitative information on the structures and dynamics of AD microbial communities. Such knowledge gap is particularly pronounced in sewage sludge AD processes although treating sewage sludge is among the major practical applications of AD. Therefore, we examined the microbial communities in three full-scale sewage sludge digesters using qualitative and quantitative molecular techniques in combination： denaturing gradient gel electrophoresis （DGGE） and real-time polymerase chain reaction （PCR）. Eight out of eleven bacterial sequences retrieved from the DGGE analysis were not affiliated to any known species while all eleven archaeal sequences were assigned to known methanogen species. Quantitative real-time PCR analysis revealed that, based on the 16S rRNA gene abundance, the hydrogenotrophic order Methanomicrobiales is the most dominant methanogen group （〉 94% of the total methanogen population） in all digesters. This corresponds well to the prevailing occurrence of the DGGE bands related to Methanolinea and Methanospirillum, both belonging to the order Methanomicrobiales, in all sludge samples. It is therefore suggested that hydrogenotrophic methanogens, especially Methanomicrobiales strains, are likely the major players responsible for biogas production in the digesters studied. Our observation is contrary to the conventional understanding that aceticlastic methanogens generally dominate methanogen communities in stable AD environments, suggesting the need for further studies on the dominance relationship in various AD systems.

关键词： anaerobic digestion hydrogenotrophic methanogens methanomicrobiales microbial community structure sewage sludge

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