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Effects of homogenization temperature on microstructure and mechanical properties of high-speed-extruded Mg–5Bi–3Al alloy

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Journal of Magnesium and Alloys 2022年第10期10卷 2833-2846页

作者： jae Won Cha Sang-Cheol Jin jae-gil jung Sung Hyuk Park School of Materials Science and Engineering Kyungpook National University80 DaehakroDaegu 41566Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effects of billet homogenization temperature on the dynamic recrystallization behavior during high-speed extrusion and resultant microstructure and tensile properties of the Mg–5Bi–3Al(BA53,wt%)*** billets homogenized at 350 and450℃(350H and 450H billets)are extruded at a high speed of 69 m/*** 350H billet has a relatively smaller grain size and a higher abundance of fine Mg3Bi2particles compared to the 450H *** extrusion of the 350H billet,enhanced dynamic recrystallization occurs as a result of its finer grains and abundance of particles,while the growth of recrystallized grains is suppressed by the grain-boundary pinning effect of ***,the extruded 350H material is characterized by smaller grains,relatively greater number of Mg3Bi2particles,and a higher internal strain energy than the extruded 450H *** tensile strength of the extruded 350H material is higher than that of the extruded 450H material owing to stronger grain-boundary hardening,particle hardening,and strain hardening *** extruded 350H material also exhibits a higher tensile elongation as its smaller grains inhibit the formation of crack-inducing undesirable twins during *** results from this study demonstrate that a decrease in the homogenization temperature from 450 to 350℃leads to improved strength and ductility in the high-speed-extruded BA53 material.

关键词： Mg–Bi–Al alloy High-speed extrusion Homogenization Dynamic recrystallization Tensile properties

Influence of undissolved second-phase particles on dynamic recrystallization behavior of Mg–7Sn–1Al–1Zn alloy during low-and high-temperature extrusions

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Journal of Materials Science & Technology 2021年第12期71卷 87-97页

作者： Hyun Ji Kim Sang-Cheol Jin jae-gil jung Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea Implementation Research Division Korea Institute of Materials ScienceChangwon51508Republic of Korea

This study investigates the effects of fine and coarse undissolved particles in a billet of the Mg–7 Sn–1 Al–1 Zn(TAZ711)alloy on the dynamic recrystallization(DRX)behavior during hot extrusion at low and high temperatures and the resultant microstructure and mechanical properties of the *** this end,partially homogenized(PH)and fully homogenized(FH)billets are extruded at temperatures of250 and 450°*** PH billet contains fine and coarse undissolved Mg_(2) Sn particles in the interdendritic region and along the grain boundaries,*** fine particles(<1μm in size)retard DRX during extrusion at 250°C via the Zener pinning effect,and this retardation causes a decrease in the area fraction of dynamically recrystallized(DRXed)grains of the extruded *** addition,the inhomogeneous distribution of fine particles in the PH billet leads to the formation of a bimodal DRXed grain structure with excessively grown grains in particle-scarce *** contrast,in the FH billet,numerous nanosized Mg_(2) Sn precipitates are formed throughout the material during extrusion at 250°C,which,in turn,leads to the formation of small,uniform DRXed grains by the grain-boundary pinning effect of the *** the PH billet is extruded at the high temperature of 450°C,the retardation effect of the fine particles on DRX is weakened by their dissolution in theα-Mg matrix and the increased extent of thermally activated grain-boundary *** contrast,the coarse Mg_(2) Sn particles in the billet promote DRX during extrusion through the particle-stimulated nucleation phenomenon,which results in an increase in the area fraction of DRXed *** both low and high extrusion temperatures,the extruded material fabricated using the PH billet,which contains both fine and coarse undissolved particles,has a lower tensile strength than that fabricated using the FH billet,which is virtually devoid of second-phase *** lower strength of the former is attributed mai

关键词： Mg–Sn alloy Second-phase particle Extrusion Homogenization Dynamic recrystallization

Prediction of grain structure in direct-chill cast Al–Zn–Mg–Cu billets using cellular automaton-finite element method

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Progress in Natural Science:Materials International 2021年第3期31卷 434-441页

作者： Min-Seok Kim Sang-Hwa Lee jae-gil jung Kwangjun Eah Department of Materials Science and Engineering Gachon University Metallic Materials Division Korea Institute of Materials Science Department of Materials Science and Engineering Yonsei University

A cellular automaton-finite element(CA-FE) model was used to predict the solidification grain structure of permanent mold cast A7086 alloy. In this model, a Gaussian distribution of nucleation sites was adopted, and the Kurz-Giovanola-Trivedi model was extended to a multicomponent Al–Zn–Mg–Cu alloy system to determine the growth kinetics of the dendrite tip. For describing the Gaussian distribution of nucleation sites on the mold surface, an empirical relationship between the initial cooling rate of the melt and the nucleation density was proposed. Under various casting conditions, the calculated grain structures agreed well with the experimental results. Subsequently, the model was applied to the direct-chill(DC) cast billets, and the simulated grain structures reproduced well the experimental results. This confirmed that the current CA-FE model can be used practically and effectively in DC casting processes.

关键词： Cellular automaton-finite element (CA-FE) model Direct-chill casting Al–Zn–Mg–Cu alloy A7068 alloy Grain structure

Comparison of macular changes according to the etiology of optic neuritis:a cross-sectional study

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International Journal of Ophthalmology(English edition) 2024年第4期17卷 686-692页

作者： Yeji Moon Sung-Min Kim jae Ho jung Department of Ophthalmology Asan Medical CenterUniversity of Ulsan College of MedicineSeoul 05505Republic of Korea Department of Neurology Seoul National University HospitalSeoul 03080Republic of Korea Department of Ophthalmology Seoul National University HospitalSeoul 03080Republic of Korea Department of Ophthalmology Seoul National University College of MedicineSeoul 03080Republic of Korea

AIM:To compare the macular structure including foveal thickness among patients with optic neuritis(ON)according to the etiology and to investigate the possible correlation between structural and visual outcomes METHODS:In this retrospective cross-sectional study,the clinical data of patients with aquaporin-4 immunoglobulin G-related ON(AQP4 group,40 eyes),myelin oligodendrocyte glycoprotein IgG-related ON(MOG group,31 eyes),and multiple sclerosis-related ON(MS group,24 eyes)were *** retinal thickness of the foveal,parafoveal and perifoveal regions were *** acuity(VA),visual field index and mean deviation were measured as visual ***:The AQP4 group showed a significantly thinner fovea(226.4±13.4μm)relative to the MOG(236.8±14.0μm,P=0.015)and MS(238.9±14.3μm,P=0.007)*** thickness in the parafoveal area also was thinner in the AQP4 group,though the difference in perifoveal retinal thickness was not *** thickness was correlated with VA in the AQP4 group(coefficientρ=-0.418,P=0.014),but not in the MOG and MS groups(P=0.218 and P=0.138,respectively).There was no significant correlation between foveal thickness and visual field test in all three ***:The significant thinning in the fovea and parafoveal areas in the AQP4 group compared to the MOG and MS groups are ***,macular changes in AQP4-ON show a significant correlation with *** results provide the possibility that retinal structural damage could reflect functional damage in AQP4-ON,distinct from MOGON and MS-ON.

关键词： foveal thickness optic neuritis aquaporin-4 immunoglobulin myelin oligodendrocyte glycoprotein multiple sclerosis

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

Exploring treatment options for biliary tract cancers:moving beyond the era of gemcitabine and platinum doublet

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Hepatobiliary Surgery and Nutrition 2024年第3期13卷 562-565页

作者： jung Sun Kim Hong jae Chon Department of Medical Oncology CHA Bundang Medical CenterCHA University School of MedicineSeongnamRepublic of Korea

Biliary tract cancers(BTCs)refer to invasive adenocarcinomas arising from the bile duct(intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma)and gallbladder(gallbladder cancer).Patients with BTCs typically present at an advanced stage due to a lack of early detection methods and non-specific symptoms;systemic chemotherapy is the cornerstone of treatment for these advanced *** plus cisplatin(GC)has been the standard treatment since the pivotal ABC-02 randomized phase 3 trial conducted in 2010(1).Moving beyond the era of GC,several triplet combination regimens have been proposed in recent years(Table 1).The combination of nab-paclitaxel(nab-P)and GC showed promising survival outcomes in a phase 2 trial(2),although it eventually failed to meet the primary endpoint of overall survival(OS)in a randomized phase 3 trial(3).Around the same time,TOPAZ-1(5)demonstrated that the programmed death ligand 1(PD-L1)inhibitor durvalumab combined with GC significantly improved the median OS[11.5 vs.12.8 months;hazard ratio(HR),0.80;95%confidence interval(CI):0.66–0.97;P=0.021]and median progression-free survival(PFS)(5.7 vs.7.2 months;HR,0.75;95%CI:0.63–0.89;P=0.001),with an objective response rate(ORR)of 26.7%.Moreover,KEYNOTE-966(6)found that the addition of programmed death-1(PD-1)inhibitor pembrolizumab also improved median OS(10.9 vs.12.7 months;HR,0.83;95%CI:0.72–0.95;P=0.0034),whereas the median PFS only showed numerical improvements(5.6 vs.6.5 months;HR,0.86;95%CI:0.75–1.00;P=0.023),with an ORR of 29%.Consequently,the combination of PD-1/PD-L1 inhibitors and GC has become the new standard of care for first-line treatment of patients with BTCs,establishing the new era of triplet combinations.

关键词： Biliary tract cancer cholangiocarcinoma gallbladder cancer

Self-assembly of tau fragments as a key pathologic event in tauopathies

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Neural Regeneration Research 2024年第12期19卷 2565-2566页

作者： Ly Thi Huong Luu Le jung Hoon Lee Min jae Lee Department of Biochemistry and Molecular Biology Seoul National University College of MedicineSeoulKorea

Tau protein is encoded by the microtubuleassociated protein tau(MAPT)gene and stabilizes microtubules in the *** has unique biophysical properties that make it both highly water-soluble and positively *** tau is an intrinsically disordered protein lacking defined secondary structures,it can acquire highly organized-sheet structures and stack into a filamentous inclusion such as a paired helical filament(PHF).

关键词： tau pathologic assembly

Significantly Improved High-Temperature Energy Storage Performance of BOPP Films by Coating Nanoscale Inorganic Layer

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Energy & Environmental Materials 2024年第2期7卷 30-38页

作者： Tiandong Zhang Hainan Yu Young Hoon jung Changhai Zhang Yu Feng Qingguo Chen Keon jae Lee Qingguo Chi School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 350701Korea

Biaxially oriented polypropylene(BOPP)is one of the most commonly used commercial capacitor films,but its upper operating temperature is below 105℃due to the sharply increased electrical conduction loss at high *** this study,growing an inorganic nanoscale coating layer onto the BOPP film's surface is proposed to suppress electrical conduction loss at high temperature,as well as increase its upper operating *** kinds of inorganic coating layers that have different energy band structure and dielectric property are grown onto the both surface of BOPP films,*** effect of inorganic coating layer on the high-temperature energy storage performance has been systematically *** favorable coating layer materials and appropriate thickness enable the BOPP films to have a significant improvement in high-temperature energy storage ***,when the aluminum nitride(AIN)acts as a coating layer,the AIN-BOPP-AIN sandwich-structured films possess a discharged energy density of 1.5 J cm^(-3)with an efficiency of 90%at 125℃,accompanying an outstandingly cyclic *** the discharged energy density and operation temperature are significantly enhanced,indicating that this efficient and facile method provides an important reference to improve the high-temperature energy storage performance of polymer-based dielectric films.

关键词： coating layer energy storage interfacial barrier polymer films

Utilization of biomarkers for the prognostic prediction of cardiac arrest survivors using a multi-modal approach

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World Journal of Emergency Medicine 2024年第2期15卷 131-134页

作者： Changshin Kang Yeonho You jung Soo Park Byeong Kwon Park jae Kwang Lee Byung Kook Lee Department of Emergency Medicine College of MedicineChungnam National UniversityDaejeon 35015Republic of Korea Department of Emergency Medicine Chungnam National University HospitalDaejoen 35015Republic of Korea Department of Emergency Medicine Konyang University HospitalCollege of MedicineDaejeon 35015Republic of Korea Department of Emergency Medicine Chonnam National University Medical SchoolChonnam National University HospitalGwangju 61469Republic of Korea

International guidelines for post-cardiac arrest care recommend using multi-modal strategies to avoid the withdrawal of life-sustaining therapy(WLST)in patients with the potential for neurological recovery.[1]However,a clear methodology for multi-modal approaches has yet to be ***-specific enolase(NSE)is currently the only recommended biomarker,and the European Resuscitation Council(ERC)and the European SocietyofIntensiveCareMedicine(ESICM)have proposed a cutoff value of 60μg/L at 48 and/or 72 h after the return of spontaneous circulation(ROSC)as a multimodal prognostic tool for predicting poor neurological outcomes.

关键词： cardiac modal return