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Friction characteristics of mechanically exfoliated and CVD-grown single-layer MoS_2

Friction 2018年第4期6卷 395-406页

作者： Dinh Le Cao KY Bien-Cuong TRAN KHAC Chinh Tam LE yong soo kim Koo-Hyun CHUNG School of Mechanical Engineering University of Ulsan Department of Physics and Energy Harvest Storage Research Center University of Ulsan

In this work, the friction characteristics of single-layer MoS2 prepared with chemical vapor deposition （CVD） at three different temperatures were quantitatively investigated and compared to those of single-layer MoS2 prepared using mechanical exfoliation. The surface and crystalline qualities of the MoS2 specimens were characterized using an optical microscope, atomic force microscope （AFM）, and Raman spectroscopy. The surfaces of the MoS2 specimens were generally flat and smooth. However, the Raman data showed that the crystalline qualities of CVD-grown single-layer MoS2 at 800 ℃ and 850 ℃ were relatively similar to those of mechanically exfoliated MoS2 whereas the crystalline quality of the CVD-grown single-layer MoS2 at 900 ℃ was lower. The CVD-grown single-layer MoS2 exhibited higher friction than mechanically exfoliated single-layer MoS2, which might be related to the crystalline imperfections in the CVD-grown MoS2. In addition, the friction of CVD-grown single-layer MoS2 increased as the CVD growth temperature increased. In terms of tribological properties, 800 ℃ was the optimal temperature for the CVD process used in this work. Furthermore, it was observed that the friction at the grain boundary was significantly larger than that at the grain, potentially due to defects at the grain boundary. This result indicates that the temperature used during CVD should be optimized considering the grain size to achieve low friction characteristics. The outcomes of this work will be useful for understanding the intrinsic friction characteristics of single-layer MoS2 and elucidating the feasibility of single-layer MoS2 as protective or lubricant layers for micro- and nano-devices.

关键词： atomic force microscope chemical vapor deposition grain boundary friction mechanical exfoliation MoS2

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Expression of apoptosis-related factors in chronic cyclosporine nephrotoxicity after cyclosporine withdrawal

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Acta Pharmacologica Sinica 2004年第4期25卷 3-13页

作者： Sun-woo LIM,Bo-kyung SUN,Bum-soon CHOI,Sylvia GLOWACKA,Alison J COX,Darren J KELLY,yong-soo kim,Jin kim,Byung-kee BANG,Chul-woo YANG Departments of Internal Medicine the Catholic University of Korea Seoul137-040 Korea Departments of Internal Medicine the Catholic University of Korea Seoul137-040 Korea Departments of Internal Medicine the Catholic University of Korea Seoul137-040 Korea Department of Medicine St Vincent’s Hospital Fitzroy University of Melbourne Australia Department of Medicine St Vincent’s Hospital Fitzroy University of Melbourne Australia Department of Medicine St Vincent’s Hospital Fitzroy University of Melbourne Australia Departments of Internal Medicine the Catholic University of Korea Seoul137-040 Korea Departments of Anatomy the Catholic University of Korea Seoul137-040 Korea Departments of Internal Medicine the Catholic University of Korea Seoul137-040 Korea Departments of Internal Medicine the Catholic University of Korea Seoul137-040 Korea MD PhD

AIM: To examine whether the reversibility of chronic cyclosporine A (CsA) nephrotoxicity is associated with apoptotic cell death and its regulatory factors. METHODS: Chronic CsA nephrotoxicity was induced in Sprague- Dawley rats by administering CsA (15 mg/kg, sc) for 5 weeks, and then withdrawing it for 5 or 10 weeks. The effect of CsA withdrawal on apoptotic cell death was evaluated by an in situ TdT-mediated deoxyuridine triphos- phate-biotin nick end-labeling (TUNEL) assay and the expression of pro-apoptotic [(transforming growth factor- beta1 (TGF-β1) and Fas] and anti-apoptotic [epidermal growth factors (EGF) and Bcl-2] factors. RESULTS: Discontinuation of CsA induced significant decreases in TUNEL-positive cells in a time-dependent manner and the reduction in TUNEL-positive cells was correlated with the tubulointerstitial fibrosis score (r=0.919, P<0.01). Upregulation of TGF-β1 and Fas expression in CsA-treated rat kidneys was decreased significantly after with- drawal of CsA. In contrast, downregulated EGF and Bcl-2 expression returned to normal or supernormal levels. CONCLUSION: CsA withdrawal is associated with a decrease in apoptotic cell death and with changes in the expression of pro-apoptotic and anti-apoptotic molecules involved in renal wound repair. This may constitute one of the mechanisms underlying the reversibility of chronic CsA nephrotoxicity.

关键词： cyclosporine apoptosis bcl-2 fas epidermal growth factor transforming growth factor-beta fibrosis

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Direct vapor phase growth process and robust photoluminescence properties of large area MoS2 layers

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Nano Research 2014年第12期7卷 1759-1768页

作者： V. Senthilkumar Le C. Tam yong soo kim Yumin Sim Maeng-Je Seong Joon. I. Jang Department of Physics and Energy Harvest Storage Research Center (EHSRC) University ofUIsan Ulsan 680-749 South Korea Department of Physics Applied Physics and Astronomy Binghamton University New York 13902 USA Department of Physics Chung-Ang University Seoul 156-756 South Korea

There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining large area thin films of MoS2 for future device applications still remains a challenge. In the present study, the amounts of the precursors （S and MOO3） were varied systematically in order to optimize the growth of highly crystalline and large area MoS2 layers by the chemical vapor deposition method. Careful control of the amounts of precursors was found to the key factor in the synthesis of large area highly crystalline flakes. The thickness of the layers was confirmed by Raman spectroscopy and atomic force microscopy. The optical properties and chemical composition were studied by photoluminescence （PL） and X-ray photoelectron spectroscopy. The emergence of strong direct excitonic emissions at 1.82 eV （A-exciton, with a normalized PL intensity of -55 × 10^3） and 1.98 eV （B-exciton, with a normalized PL intensity of -5 × 10^3） of the sample at room temperature clearly indicates the high luminescence quantum efficiency. The mobility of the films was found to be 0.09 cm^2/（V.s） at room temperature. This study provides a method for the controlled synthesis of high-quality two-dimensional （2D） transition metal dichalcogenide materials, useful for applications in nanodevices, optoelectronics and solar energv conversion.

关键词： molybdenum disulfide CVD growth large area Raman photo-luminescence field-effect ransistor (FET)

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Clinical implications of fatty pancreas:Correlations between fatty pancreas and metabolic syndrome

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World Journal of Gastroenterology 2009年第15期15卷 1869-1875页

作者： Jun Seok Lee Sang Heum kim Dae Won Jun Jee Hye Han Eun Chul Jang Ji Young Park Byung Kwan Son Seong Hwan kim Yoon Ju Jo Young sook Park yong soo kim Department of Internal Medicine Eulji University School of Medicine Department of Radiology Eulji University School of Medicine Department of Family Medicine Eulji University School of Medicine Department of Occupational and Environmental Medicine College of MedicineSoonchunhyang University Department of Radiology Hanyang University School of Medicine

AIM:To investigate the clinical implications of lipid deposition in the pancreas(fatty pancreas). METHODS:The subjects of this study were 293 patients who had undergone abdominal computed tomography(CT)and *** pancreas was diagnosed by sonographic findings and subdivided into mild,moderate,and severe fatty pancreas groups comparing to the retroperitoneal fat echogenicity. RESULTS:Fatty pancreas was associated with higher levels for visceral fat,waist circumference,aspartate aminotransferase(AST),alanine aminotransferase (ALT),total cholesterol,triglyceride,high density lipoprotein,free fatty acid,γ-GTP,insulin,and the homeostasis model assessment of insulin resistance (HOMA-IR)than the control group(P<0.05).HOMAIR,visceral fat,triglyceride,and ALT also tended to increase with the degree of fat deposition in the pancreas on *** a multivariate logistic regression analysis,HOMA-IR,visceral fat,and ALT level were independently related to fatty pancreas after adjustment for age,body mass index,and lipid *** incidence of metabolic syndrome in the fatty pancreas group was significantly higher than in the control group,and the numbers of metabolic syndrome parameters were significantly higher in the fatty pancreas group(P<0.05).CONCLUSION:Sonographic fatty pancrease showed higher insulin resistance,visceral fat area,triglyceride, and ALT levels than normal *** pancreas also showed a strong correlation with metabolic syndrome.

关键词： Fatty pancreas Metabolic syndrome Insulin resistance

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Numerical Analysis of Two-Phase Flow in Inclined Channel with Downward- Facing Heated Wall

Numerical Analysis of Two-Phase Flow in Inclined Channel wit...

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The Fifth China-Korea Workshop on Nuclear Reactor Thermal Hydraulics

作者： Hae-Kyun Park Wan-Sik Yeon Kwang-Hyun Bang Jungsoo Suh yong soo kim Department of Mechanical and Energy Systems Engineering Korea Maritime University 1 Dongsam-dong Yeongdo-gu Busan 606-791 S.Korea Advanced Power Plant Development Office KHNP Central Research Institute Korea Hydro & Nuclear Power Co.25-1 Jang-dong Yuseong-gu Daejeon 305-343 S.Korea

Wall boiling and bubble population balance equations combined with a two-fluid model are employed to predict boiling two-phase flow in an inclined channel with downward- facing heated wall. For vertical flow, these models have been highlighted by the mechanistic formulation of bubble nucleation on a vertical heated wall by the bubble sliding and lift-off formulations. For downward-facing heated wall in an inclined channel, however, the bubble nucleation and departure behaviors are affected by the large bubbles near the heated wall as vapor accumulates near the upper wall of the inclined channel. In order to observe the boiling behavior on the inclined, downward-facing heated wall, a visualization experiment was carried out with a 100 mm x 100 mm of the cross section, one meter long rectangular channel, inclined by 10 o from the horizontal plane. The size of the heated wall was 50 mm by 750 mm and the heat flux was provided by the Joule heating of the heated wall using the DC electrical current. High speed video images showed the bubble nucleation and growth, sweeping of these bubbles by a large bubble sliding near the wall. For these circumstances of wall boiling and two-phase flow in the inclined channel, the existing wall boiling model encompassing bubble growth and sliding were modified by considering the influence of large bubbles near the heated wall. Using the model developed, boiling two-phase flow in a 3 m long, inclined channel with downward-facing heated wall was analyzed.

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Prominent cycling reversibility and kinetics enabled by CaTiO3 protective layer on Zn metal for aqueous Zn-ion batteries

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Journal of Energy Chemistry 2025年第1期100卷 245-258页

作者： Gaeun Lee yong Nam Ahn Seongjoon So Chanwoo Park Jong-Seong Bae Taehyun Park Il Tae kim Jaehyun Hur School of Chemical Biological and Battery Engineering Gachon University Seongnam Busan Center Korea Basic Science Institute

Aqueous Zn-ion batteries （AZIBs） have received considerable attention owing to their various advantages such as safety,low cost,simple battery assembly conditions,and high ionic ***,they still suffer from serious problems,including uncontrollable dendrite growth,corrosion,hydrogen evolution reaction （HER） from water decomposition,electrode passivation,and unexpected *** creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these ***,we propose the use of a perovskite CaTiO3（CTO） protective layer on Zn（CTO@Zn） as a promising approach for improving the performance of *** CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant （εr=180） and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn2+ions in the CTO *** avoiding the direct contact of the Zn anode with the electrolyte solution,the uneven dendrite growth,corrosion,parasitic side reactions,and HER are mitigated,while CTO retains its mechanical and chemical robustness during ***,CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare ***@Zn shows steady overpotential （～68 m V） for 1500 h at 1 mA cm-2/0.5 mA h cm-2,excelling bare ***,when paired with the V2O5-C cathode,the CTO@Zn//V2O5-C full battery delivers 148.4 mA h g-1（based on the mass of the cathode） after 300 *** study provides new insights into Zn metal anodes and the development of high-performance AZIBs.

关键词： Artificial layer Dielectric constant Zn metal anode Zinc aqueous battery

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Apolipoprotein A-I binding protein-mediated neuroprotection in glaucomatous neuroinflammation and neurodegeneration

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Neural Regeneration Research 2025年第5期20卷 1414-1415页

作者： Sinwoo Hwang Seunghwan Choi soo-Ho Choi Keun-Young kim Yury I.Miller Won-Kyu Ju Hamilton Glaucoma Center and Shiley Eye Institute The Viterbi Family Department of OphthalmologyUniversity of California San DiegoLa JollaCAUSA Department of Medicine University of California San DiegoLa JollaCAUSA National Center for Microscopy and Imaging Research Department of NeurosciencesUniversity of California San DiegoLa JollaCAUSA

Glaucoma is a multifactorial eye disorder that can cause vision loss and irreversible blindness,affecting individ uals aged 40 to 80 yea rs *** to the aging population,it is expected that the number of people affected by glaucoma will surpass 111 million by 2040 as the disease becomes more *** primarily contributes to optic nerve axon loss and the progressive degeneration of retinal ganglion cells (RGCs),subsequently leading to vision impairment.

关键词： irreversible pass primarily

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Distinctive clinical features of spontaneous pneumoperitoneum in neonates: A retrospective analysis

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World Journal of Clinical Cases 2022年第23期10卷 8124-8132页

作者： soo-Hong kim yong-Hoon Cho Hae-Young kim Department of Surgery Pusan National University Yangsan HospitalPusan National University School of MedicineYangsan 50612South Korea Research Institute for Convergence of Biomedical Science and Technology Pusan National University Yangsan HospitalYangsan 50612South Korea

BACKGROUND Spontaneous pneumoperitoneum(SP) without gastrointestinal perforation rarely occurs in neonates, with most SP cases being idiopathic. Although SP usually follows a benign clinical course with favorable prognosis, it can become lifethreatening in certain situations. In these cases, urgent surgical intervention may be required. Therefore, it may be difficult to decide when or how to perform prompt *** To demonstrate the distinct clinical features of SP to guide appropriate management by comparing characteristics between SP and typical pneumoperitoneum secondary to gastrointestinal *** We retrospectively reviewed electronic medical records and identified 37 neonates with radiological evidence of pneumoperitoneum who were treated at our institution. Clinical variables were compared between neonates with SP without gastrointestinal perforation(Group A) and those with pneumoperitoneum secondary to gastrointestinal perforation(Group B). Clinical variables between groups were compared using Student’s t-test and the chi-square test. The risk factors related to mortality were examined using multi-logistic regression *** Group A comprised 35.1%(13/37) of the patients. The frequency of persistent pulmonary hypertension(53.8%) and pneumothorax(46.2%) before the development of pneumoperitoneum was significantly higher in group A than in group B(P =0.004). Platelet count and partial pressure of arterial oxygen(PaO) were significantly lower in group A(P = 0.015 and 0.025, respectively). Overall mortality was significantly higher in group A than in group B(76.9% vs 16.7%, P = 0.001). Only preterm infants were significantly associated with high mortality(P = 0.041;odds ratio = 18.0). Accompaniment with persistent pulmonary hypertension and pneumothorax were also significantly high(P = 0.004) in group A, but these were not strongly associated with high *** This study identified a higher mortality rate in patients w

关键词： Spontaneous pneumoperitoneum Thrombocytopenia Persistent pulmonary hypertension Pneumothorax Preterm

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Characteristics of machined surface controlled by cutting tools and conditions in machining of brittle material

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中国有色金属学会会刊：英文版 2009年第B9期19卷 194-201页

作者： yong-Woo kim soo-Chang CHOI Jeung-Woo PARK Deug-Woo LEE Department of Nano Fusion Technology Pusan National University Department of Mechanical Design Engineering Chosun University Department of Nanosystem and Nanoprocess Engineering Pusan National University

One of the ultra-precision machining methods was adapted for brittle material as well as soft material by using multi-arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because the particles of grinding tools are irregular size and material can be fragile. Therefore, we were able to design tool paths and machine controlled pattern on surface by multi-arrayed diamond tips with uniform size made in MEMS fabrication and high speed spindle, and the maximum speed was about 3×105 r/min. We defined several parameters that can affect the machining surface. Those were multi-array of diamond tips (n×n), speed of air spindle and feeding rate. The surface roughness and surface texture can be controlled by those parameters for micro machining.

关键词：加工表面脆性材料条件控制刀具路径表面粗糙度特征高速主轴加工方法

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Surgical perspectives of symptomatic omphalomesenteric duct remnants: Differences between infancy and beyond

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World Journal of Clinical Cases 2021年第36期9卷 11228-11236页

作者： Ayoung Kang soo-Hong kim yong-Hoon Cho Hae-Young kim Department of Surgery Pusan National University Yangsan HospitalYangsan 50612South Korea Department of Surgery Pusan National University School of MedicineYangsan 50612South Korea Research Institute for Convergence of Biomedical Science and Technology Pusan National University Yangsan HospitalYangsan 50612South Korea

BACKGROUND The clinical manifestations of omphalomesenteric duct remnant(OMDR)can vary with the age at diagnosis,from asymptomatic incidental findings to symptoms related to gastrointestinal *** lifelong complication rates are reported as 4%-34%,and complications are more common in patients younger than 2 years of *** authors attempted to identify different clinical features and management for the various pediatric age *** To find surgical perspectives for the pediatric age-related variants of OMDR and make recommendations for optimal *** The medical records of pediatric patients diagnosed with OMDR were reviewed *** patients diagnosed based on incidental findings during other surgeries were *** patients were divided into two groups based on age:12 mo(beyond infancy).We analyzed the demographic characteristics,clinical manifestations,diagnostic tools,surgical procedures,and clinical outcomes of the patients and compared them for the age ***-squared and Fisher's exact tests were used for nominal scales and a Mann-Whitney test was used for ratio *** A total of 35 patients(7 infants,28 children beyond infancy)were finally *** both groups,Meckel's diverticulum(MD)was the most common type of OMDR,while umbilical lesions were more common in the infant group(P=0.006).Hematochezia and abdominal pain were common in the beyond infancy group,while umbilical lesions were the most frequent symptoms in the infant *** diagnostic tools were used,but Meckel's scan was most useful in diagnosing OMDR in patients with painless rectal *** invasive surgery was more commonly performed for children than for infants(P=0.016).Single-incision laparoscopic surgery(SILS)was performed for fifteen patients who underwent laparoscopic *** were only three cases of postoperative complications,and all patients survived in good *** The cli

关键词： Omphalomesenteric duct remnant Age Surgical Meckel's diverticulum Single-incision laparoscopic surgery Children

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