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Modeling asymmetric fracture mechanics of Mg alloy wire in drawing process

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Journal of Magnesium and Alloys 2024年第5期12卷 2057-2069页

作者： Sunghoon choi Jongwon Shin Joung sik Suh Dongchoul Kim Department of Mechanical Engineering Sogang UniversitySeoul04107Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

In this study,a numerical analysis was conducted on the ductile fracture of a 2-mm diameter Mg-1Zn-0.5Mn-0.5Sr-0.1Ca alloy wire during *** hexagonally close-packed crystal structure of Mg alloys causes asymmetric fracture behavior,especially in the compression *** aim of this study is to develop a comprehensive damage model for Mg alloy wire that accurately predicts ductile fracture,with a focus on the compression region.A novel experimental method was introduced to measure the ductile fracture of Mg alloy wires under different stress *** wire drawing process was simulated using the Generalized Incremental Stress-State dependent damage(GISSMO)Model and the Semi-Analytical Model for Polymers(SAMP)*** damage model's prediction and the experimental results were found to be in excellent agreement,especially in determining crack *** analysis established a safe zone diagram for die angle and reduction ratio,and experimental validation confirmed the feasibility of this *** proposed damage model can provide a practical and reliable analysis for optimizing the drawing process of Mg alloy wire.

关键词： Mg alloy Wire drawing Finite element method Damage model Safe zone diagram

Unravelling the role of the combined effect of metallic charge transfer channel and SiO_(x) overlayer in the Zr/Si-Fe_(2)O_(3):Au:SiO_(x) nanorod arrays to boost photoelectrochemical water splitting

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Journal of Energy Chemistry 2024年第3期90卷 370-379,I0009页

作者： Tae sik Koh Periyasamy Anushkkaran Love Kumar Dhandole Mahadeo A.Mahadik Weon-sik Chae Hyun Hwi Lee Sun Hee choi Jum Suk Jang Division of Biotechnology SafetyEnvironment and Life Science InstituteCollege of Environmental and Bioresource SciencesJeonbuk National UniversityIksan 54896Republic of Korea Department of Integrative Environmental Biotechnology College of Environmental and Bioresource SciencesJeonbuk National UniversityIksan 54596Republic of Korea Extreme Materials Research Center Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Daegu Center Korea Basic Science InstituteDaegu 41566Republic of Korea Pohang Accelerator Laboratory Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea

Hematite(α-Fe_(2)O_(3)) based photoanodes have been extensively studied due to various intriguing features that make them viable candidates for a photoelectrochemical(PEC) water splitting ***,we propose a Zr-doped Fe_(2)O_(3) photoanode decorated with facilely spin-coated Au nanoparticles(NPs) and microwave-assisted attached Si co-doping in conjunction with a SiO_(x) overlayer that displayed a remarkable photocurrent density of 2.01 mA/cm^(2) at 1.23 V *** kinetic dynamics at the photoelectrode/-electrolyte interface was examined by employing systematic electrochemical *** Au NPs played a dual role in increasing PEC water ***,the Schottky interface that was formed between Au NPs and Zr-Fe_(2)O_(3) lectrode ensured the prevention of electron flow from the photoanode to the metal,increasing the number of available charges as well as suppressing surface charge ***,Au extracted photoholes from the bulk of the Zr-Fe_(2)O_(3) and transported them to the outer SiO_(x) overlayer,while the SiO_(x) overlayer efficiently collected the photoholes and promoted the hole injection into the ***,Si co-doping enhanced bulk conductivity by reducing bulk charge transfer resistance and improving charge carrier *** study outlines a technique to design a metallic charge transfer path with an overlayer for solar energy conversion.

关键词： Hematite Microwave attachment Au nanoparticles SiO_(x) overlayer Water splitting

Absence of enhancement in a lesion does not preclude primary central nervous system T-cell lymphoma:A case report

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World Journal of Clinical Cases 2024年第2期12卷 374-382页

作者： Chan-Seop Kim Chi-Hoon choi Kyung sik Yi Yook Kim Jisun Lee Chang Gok Woo Young Hun Jeon Department of Radiology Chungbuk National University HospitalChungbuk National University College of MedicineCheongju-si 28644Chungcheongbuk-doSouth Korea Department of Pathology Chungbuk National University HospitalChungbuk National University College of MedicineCheongju-si 28644Chungcheongbuk-doSouth Korea Department of Radiology Seoul National University HosptialSeoul 03080South Korea

BACKGROUND Primary central nervous system lymphoma(PCNSL)is a non-Hodgkin lymphoma that originates in the central nervous system(CNS)and is exclusively limited to the *** most PCNSLs are diffuse large B-cell lymphomas,primary CNS T-cell lymphomas(PCNSTLs)are *** typically demonstrate some degree of enhancement on contrast-enhanced magnetic resonance imaging(MRI).To the best of our knowledge,non-enhancing PCNSTL has not been reported *** SUMMARY A 69-year-old male presented to the neurology department with complaints of mild cognitive impairment and gradual onset of left lower leg weakness over a span of two *** MRI showed asymmetric T2-hyperintense lesions within the *** enhancement was observed on the contrast-enhanced T1 *** initial diagnosis was neuro-Behçet’s *** high-dose steroid therapy,no alterations in the lesions were identified on initial *** patient’s symptoms deteriorated *** MRI performed one month after the initial scan revealed an increased lesion ***,brain biopsy confirmed the diagnosis of *** patient underwent definitive combined ***,the patient developed bacteremia and died of septic shock approximately three months after *** The absence of enhancement in the lesion did not rule out PCNSTL.A biopsy approach is advisable for pathological confirmation.

关键词： Central nervous system neoplasms Non-Hodgkin Lymphoma T-cell Lymphoma Primary central nervous system lymphoma Primary central nervous system T-cell lymphoma Case report

Clinical significance of surgical resection for hepatocellular carcinoma with portal vein invasion:a nationwide cohort study

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Hepatobiliary Surgery and Nutrition 2024年第5期13卷 814-823,I0006-I0008页

作者： Hye-Sung Jo Pyoung-Jae Park Young-Dong Yu Yoo Jin choi Se Hyeon Yu Dong-sik Kim Korean Liver Cancer Association Division of HBP Surgery and Liver Transplantation Department of SurgeryKorea University College of MedicineSeoulRepublic of Korea Division of Transplantation and Vascular Surgery Department of SurgeryKorea University Guro HospitalKorea University College of MedicineSeoulRepublic of Korea

Background:Hepatocellular carcinoma(HCC)with portal vein invasion(PVI)is considered an advanced stage with a poor *** current guidelines recommend systemic treatment for HCC with PVI,surgical resection could produce acceptable outcomes in selected *** study aimed to identify the clinical significance of surgical resection for HCC with PVI patients using a large-scale nationwide ***:This retrospective,multicenter,observational cohort analyzed data from the Korean Primary Liver Cancer Registry.A total of 16,781 patients who were newly diagnosed with HCC between 2008 and 2018 were enrolled in this *** with worse Child-Turcotte-Pugh scores(≥7)or performance status(≥2)were *** them,998 patients who received treatment for HCC with PVI were included in the analysis and were divided into two groups:resection group of 151(15.1%)and palliative group of 847(84.9%)who received transarterial and systemic therapy according to the treatment *** matching the number and size of the tumors and model for end-stage liver disease(MELD)score between the groups,the final study cohort for analysis comprised 151(26.6%)patients in the resection group and 417(73.4%)in the palliative *** primary endpoints were overall survival(OS)and cancer-specific survival(CSS).Results:The number and maximum size of HCC did not differ between the resection and palliative groups after matching[1(range,1-5)vs.1(range,1-6),P=0.11 and 5.5(range,1.2-20.6)vs.6.0(range,1.0-20.5)cm,P=0.24,respectively].Tumor markers,including alpha-fetoprotein(AFP)and protein induced by vitamin K absence or antagonist-II(PIVKA-II),also did not differ between the groups(P=0.29 and P=0.36,respectively).The 5-year OS and CSS rates of the resection and palliative groups were 44.8%and 17.4%(P<0.001)and 47.7%and 18.6%(P<0.001),*** analysis showed that palliative treatment intent was the most significant risk factor for OS and CSS[odds ratio(OR

关键词： Hepatocellular carcinoma(HCC) portal vein invasion(PVI) overall survival(OS) cancer-specific survival(CSS) surgical resection

Ex situ aging effect on sulfonated poly(ether ether ketone) membrane:Hydration-dehydration cycling and hydrothermal treatment

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Journal of Energy Chemistry 2022年第7期31卷 583-592,I0014页

作者： Seung-Young choi Kyeong sik Jin Polymer&Materials Chemistry Department of ChemistryLund UniversitySE-22100Sweden Center for Hydrogen·Fuel Cell Research Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Pohang Accelerator Laboratory Pohang University of Science and Technology(POSTECH)PohangKyungbuk 37673Republic of Korea

Prolonged hydrothermal treatment for sulfonated poly(ether ether ketone) membranes induces mechanical degradation and developing hydrophilic-hydrophobic phase separation, simultaneously. The enhanced phase separation provides incremental proton conductivity to the membranes, whereas mechanical degradation drastically reduces device stability. On this basis, we describe here the effects of two different ex situ aging processes on sulfonated poly(ether ether ketone) membranes: hydrationdehydration cycling and prolonged hydrothermal treatment. Both aged membranes exhibited enhanced phase separation under the hydrated conditions, as characterized by small angle X-ray ***, when the aged membranes were dried again, the nanostructure of the membranes aged via the hydration-dehydration cycling was recoverable, whereas that of the membranes aged via prolonged hydrothermal treatment was irreversible. Furthermore, the two differently aged membranes showed clear differences in thermal, mechanical, and electrochemical properties. Finally, we implemented both aged membranes in fuel cell application. The sample aged via hydration-dehydration cycling maintained its improved cell performance, whereas the sample aged via hydrothermal treatment showed drastically reduced cell performance after durability test for 50 h.

关键词： Sulfonated poly(ether ether ketone) Humidity cycle test Ex situ aging Proton exchange membrane Fuel cell

Evaluation of esophageal function in patients with esophageal motor abnormalities using multichannel intraluminal impedance esophageal manometry

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World Journal of Gastroenterology 2006年第39期12卷 6349-6354页

作者： Yu Kyung Cho myung-Gyu choi Jae myung Park Jung Hwan Oh Chang Nyol Paik Joon Wook Lee In Seok Lee Sang Woo Kim In-sik Chung Division of Gastroenterology Department of Internal Medicine The Catholic University of Korea Seoul Korea

AIM: To evaluate the functional aspect of esophageal motility in healthy subjects and in patients who were referred for esophageal function testing using multichannel intraluminal impedance-esophageal manometry (MII-EM), and to assess the clinical utility of MII-EM. METHODS: From September 2003 to January 2004, we performed the MII-EM on healthy volunteers and all the patients who were referred for esophageal function testing. Each patient received 10 liquid and 10 viscous swallows. We analyzed the results, the impedance and the manometric findings. Some of the subjects had additional ambulatory 24-h pH study performed to diagnose gastroesophageal reflux disease (GERD). RESULTS: Among 89 studied subjects, the MII-EM findings showed normal esophageal motility in 50 (56.17%), ineffective esophageal motility (IEM) in 17 (19.10%), nutcracker esophagus in 7 (7.86%), achalasia in 4 (4.49%), and scleroderma esophagus in 11 (12.35%) cases. The completeness and the speed of bolus transit were in the order of nutcracker esophagus, normal manometry and IEM. Some of the swallows showing normal manometry and IEM had incomplete transit. In the achalasia and scleroderma esophagus, almost all the swallows had incomplete transit. The body amplitudes were higher for the swallows with complete transit than for the swallows with incomplete transit. There was not a significant difference in the manometric and impedance findings between the subjects with and without GERD. CONCLUSION: MII-EM is a useful tool in assessing theesophageal function in the patients having esophageal motility abnormality. The primary factors influencing the bolus transit are the amplitude of the esophageal body and normal peristalsis.

关键词： Impedance manometry Esophageal function Motility Bolus transit

Clinical outcomes of self-expandable metal stents in palliation of malignant anastomotic strictures caused by recurrent gastric cancer

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World Journal of Gastroenterology 2009年第28期15卷 3523-3527页

作者： Yu Kyung Cho Sang Woo Kim Kwan Woo Nam Jae Hyuck Chang Jae myung Park Jeong-Jo Jeong In Seok Lee myung-Gyu choi In-sik Chung Department of Internal Medicine The Catholic University of Korea

AIM： To examine the technical feasibility and clinical outcomes of the endoscopic insertion of a selfexpandable metal stent （SEMS） for the palliation of a malignant anastomotic stricture caused by recurrent gastric cancer. METHODS： The medical records of patients, who had obstructive symptoms caused by a malignant anastomotic stricture after gastric surgery and underwent endoscopic insertion of a SEMS from January 2001 to December 2007 at Kangnam St Mary＇s Hospital, were reviewed retrospectively. RESULTS： Twenty patients （15 male, mean age 63 years） were included. The operations were a total gastrectomy with esophagojejunostomy （n = 12）, subtotal gastrectomy with Billroth-Ⅰ reconstruction （n = 2） and subtotal gastrectomy with Billroth- Ⅱ reconstruction （n = 8）. The technical and clinical success rates were 100% and 70%, respectively. A small bowel or colon stricture was the reason for a lack of improvement in symptoms in 4 patients. Two of these patients showed improvement in symptoms after another stent was placed. Stent reobstruction caused by tumor ingrowth or overgrowth occurred in 3 patients （15%） within 1 mo after stenting. Stent migration occurred with a covered stent in 3 patients who underwent a subtotal gastrectomy with Billroth-Ⅱ reconstruction. Two cases of partial stent migration were easily treated with a second stent or stent repositioning. The median stent patency was 56 d （range, 5-439 d）. The median survival was 83 d （range, 12-439 d）. CONCLUSION： Endoscopic insertion of a SEMS provides safe and effective palliation of a recurrent anastomotic stricture caused by gastric cancer, A meticulous evaluation of the presence of other strictures before inserting the stent is essential for symptom improvement.

关键词： Stents Surgical anastomosis Stricture Endoscopic gastrointestinal surgery Stomach neoplasms

Meso-porous silicon-coated carbon nanotube as an anode for lithium-ion battery

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Nano Research 2016年第7期9卷 2174-2181页

作者： Won-sik Kim Jonghyun choi Seong-Hyeon Hong Department of Materials Science and Engineering and Research Institute of Advanced Materials Seoul National University Seoul 151-744 Republic of Korea

Meso-porous Si-coated carbon nanotube （CNT） composite powders were prepared by combining a sol-gel method and the magnesiothermic reduction process. Meso-porous Si-coated CNT electrodes exhibit excellent cycle and rate performances as anodes in Li-ion batteries （LIBs）, which can be attributed to the efficient accommodation of volume change from meso-porous Si structure and the enhanced electrical conductivity from CNT core. This simple synthesis and subsequent reduction process provide a scalable route for the large-scale production of Si-C composite nanostructures, which can be utilized in a variety of applications, such as in photocatalysis, photoelectrochemical cells （PECs）, and LIBs.

关键词： meso-porous carbon nanotube (CNT) magnesiothermic reduction battery

Chronic gastrointestinal symptoms and quality of life in the Korean population

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World Journal of Gastroenterology 2008年第41期14卷 6388-6394页

作者： Jeong-Jo Jeong myung-Gyu choi Young-Seok Cho Seung-Geun Lee Jung-Hwan Oh Jae-myung Park Yu-Kyung Cho In-Seok Lee Sang-Woo Kim Sok-Won Han Kyu-Yong choi In-sik Chung Department of Internal Medicine the Catholic University of Korea Department of Biostatistics University of North Carolina at Chapel Hill NC

AIM： To evaluate the prevalence of chronic gastroin- testinal symptoms and their impact on health-related quality of life （HRQOL） in the Korean population. METHODS： A cross-sectional survey, using a reliable and valid Rome I] based questionnaire, was per- formed on randomly selected residents, between 18 and 69 years in age. All respondents were interviewed at their homes or offices by a team of interviewers. The impact of chronic gastrointestinal symptoms on HRQOL was assessed using the Korean version of the 36-item Short-Form general health survey （SF-36）. RESULTS： Of the 1807 eligible subjects, 1417 （78.4%： male 762; female 655） were surveyed. Out of the respondents, 18.6% exhibited at least one chronic gastrointestinal symptom. The prevalence of gastro- esophageal reflux disease （GERD）, defined as heart- burn and/or acid regurgitation experienced at least weekly, was 3.5% （95% CI, 2.6-4.5）. The prevalence of uninvestigated dyspepsia, irritable bowel syndrome （IBS） and chronic constipation based on Rome Ⅱ criteria were 11.7% （95% CI, 10.1-13.5）, 2.2% （95% CI, 1.5-3.1）, and 2.6% （95% CI, 1.8-3.5） respectively. Compared with subjects without chronic gastrointesti- nal symptoms （n = 1153）, those with GERD （n = 50）, uninvestigated dyspepsia （n = 166） and IBS （n = 31） had significantly worse scores on most domains of the SF-36 scales. CONCLUSION： The prevalence of GERD, uninvesti- gated dyspepsia and IBS were 3.5%, 11.7% and 2.2% respectively, in the Korean population. The health- related quality of life was significantly impaired in subjects with GERD, uninvestigated dyspepsia and IBS in this community.

关键词： Chronic gastrointestinal symptom Gastroesophageal reflux disease Dyspepsia Irritable bowel syndrome Qaulibl of life