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2D reduced graphene oxide-titania nanocomposites synthesized under different hydrothermal conditions for treatment of hazardous organic pollutants

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Particuology 2018年第1期16卷 165-173页

作者： Migyeong kim won-Hwa Hong Woong kim Sung Hyuk Park Wan-Kuen Jo Department of Environmental Engineering Kyungpook National University Daegu 702-701 Republic of Korea School of Architecture Kyungpook National University Daegu 702-701 Republic of Korea Department of Materials Science and Metallurgical Engineering Kyungpook National University Daegu 702-701 Republic of Korea

Two-dimensional reduced graphene oxide-titania （RGO-TiO2） composites were prepared using a single- step hydrothermal method under various hydrothermal reaction conditions. The morphological and surface characteristics of the RGO-TiO2 composites and reference materials were determined. The RGO-TiO2 composites showed photocatalytic activity for the decomposition of two target pollutants that was superior to both pure TiO2 and RGO under fluorescent daylight lamp illumination. The photo- catalytic activity of the RGO-TiO2 composite increased as the hydrothermal treatment time increased from 1 to 24 h, but then it decreased as the time increased to 36 h, which indicated the presence of an optimal treatment time. RGO-TiO2 composites activated by violet light-emitting diodes （LEDs） displayed lower decomposition efficiency than those activated by a daylight lamp, likely because of the lower light intensity of violet LEDs （0.2 mW/cm2） when compared with that of the daylight lamp （1.4mW/cm2）. However, the photocatalytic decomposition of the target pollutants using the RGO-TiO2 composite was more energy-efficient using the violet LEDs. The photocatalytic reaction rates increased as the residence time decreased, whereas the reverse was true for the decomposition efficiency.

关键词： TiO2 composite Continuous-flow mode Hydrothermal time VioletLight emitting diode

Hepatitis B virus pre S1 deletion is related to viral replication increase and disease progression

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World Journal of Gastroenterology 2015年第16期21卷 5039-5048页

作者： Seoung-Ae Lee Ki-Jeong kim Hong kim won-Hyuk Choi Yu-Sub won Bum-Joon kim Department of Biomedical Sciences Microbiology and Immunologyand Liver Research InstituteSeoul National University College of Medicine Department of Microbiology School of MedicineChung-Ang University Department of Internal Medicine Konkuk University

AIM:To investigate the clinical implications of hepatitis B virus(HBV) pre S1 ***:We developed a fluorescence resonance energy transfer-based real-time polymerase chain reaction(RT-PCR) that can detect four genotypes(wild type, 15-bp, 18-bp and 21-bp deletion).The PCR method was used in two cohorts of Korean chronic HBV subjects with genotype C *** Ⅰ included 292 chronic HBV subjects randomly selected from Cheju National University Hospital(Jeju, South Korea) or Seoul National University Hospital(Seoul, South Korea), and cohort Ⅱ included 90 consecutive chronic HBV carriers recruited from Konkuk University Hospital(Seoul, South Korea); the cohort Ⅱ patients did not have hepatocellular carcinoma or liver ***:The method proposed in this study identified 341 of 382 samples(89.3%).Deletion variants were identified in 100(29.3%) of the 341 detected *** both cohorts, the subjects with deletions had a significantly higher Hepatitis B virus e antigen(HBe Ag)-positive seroprevalence [cohort Ⅰ, wild(51.0%) vs deletion(75.0%), P < 0.001; cohort Ⅱ, wild(69.2%) vs deletion(92.9%), P = 0.002] and higher HBV DNA levels [cohort Ⅰ, wild(797.7 pg/m L) vs deletion(1678.9 pg/m L), P = 0.013; cohort Ⅱ, wild(8.3 × 108 copies/m L) vs deletion(2.2 × 109 copies/m L), P = 0.049], compared to subjects with wild type ***:HBV genotype C pre S1 deletion may affect disease progression in chronic HBV subjects through an extended duration of HBe Ag seropositive status and increased HBV replications.

关键词： Hepatitis B virus PreS1 start codon deletion Hepatitis B virus e antigen Hepatocellular carcinoma Genotype C

Microstructure and Tensile Behavior of a Nano-Structured Al-Fe Based Alloy

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Journal of Rare Earths 2004年第Z2期22卷 65-68页

作者： won-Yong kim Jae-Sung Park Mok-Soon kim Tae-Yeub Ra Advanced Materials R&D Center Korea Institute of Industrial Technology # 472Kajwa-dongSuh-guIncheon 404-254Korea School of Materials Science and EngineeringInha University # 253Yonghyun-dongNam-guIncheon 402-751Korea School of Materials Science and EngineeringInha University # 253Yonghyun-dongNam-guIncheon 402-751Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology # 472Kajwa-dongSuh-guIncheon 404-254Korea

Room temperature deformation behavior of A1-8Fe-2Mo-2V-1Zr alloy produced by spray forming and subsequent warm-extrusion at 693 K and/or rolling at 423 K was investigated in terms of tensile test and microstructural *** the specimen processed by spray forming and warm extrusion, the microstructure consisting of equiaxed grains with the average grain size of 500 nm in the matrix phase and uniformly dispersed fine intermetallic A13(Fe, Mo, V, Zr) and A16(Fe, Mo, V, Zr) phases less than 100 nm was characterized. It was revealed that subsequent warm rolling after warm extrusion promotes precipitation of a fine dispersoid from the supersaturated matrix phase. Warm rolling was found to be effective to increase the yield and tensile strength in the high strain rate regime. Elongation of the warm rolled specimen showed highe r value than extruded specimen over the whole strain rate region studied.

关键词： microstructure tensile deformation A1-Fe based alloy spray forming extrusion warm rolling precipitation strain rate sensitivity

Flexible thermocouple using a thermoelectric graphene fiber with a seamless junction

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Journal of Materials Science & Technology 2024年第5期172卷 15-22页

作者： Seungwon kim Soomook Lim Myeong Hee Jeong wonjoon kim Seunghyun Baik Ji won Suk School of Mechanical Engineering Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea Department of Smart Fab.Technology Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea SKKU Advanced Institute of Nanotechnology(SAINT) Sungkyunkwan UniversitySuwonGyeonggi-do 16419Republic of Korea

Temperature is an important physical variable that indicates the condition of the human body and artificial *** wearable applications require the development of temperature sensors with different form *** this study,a fiber-shaped thermoelectric temperature sensor is fabricated using a continuous graphene fiber whose two halves possess different reduction states.A seamless junction is formed by partially reducing a wet-spun graphene oxide fiber with hydroiodic acid(HI)solutions of different ***-half of the fiber is mildly reduced with 0.97 wt%HI,while the other half is highly reduced with 30.6 wt%*** different reduction states of the graphene composite fiber result in different Seebeck coefficients,allowing for the fabrication of a fiber-shaped graphene thermocou-ple without any laborious *** flexible graphene thermocouple exhibits high sensitivity with a thermopower of 12.5μV K^(-1)in the temperature range of room temperature to∼70℃.Furthermore,it exhibits high linearity with a correlation coefficient exceeding 0.995 and fast response with a time constant of 0.24 *** to its mechanical robustness and flexibility,the stand-alone graphene ther-mocouple can be knitted into a cotton fabric glove,which presents a fast response to environmental changes without any external power *** work offers a unique fabrication method for producing a high-performance,flexible thermocouple that features a seamless and clear junction without the use of additional *** alternative method eliminates the complicated assembly processes typically required for conventional thermocouples.

关键词： Graphene fiber Thermocouple Reduced graphene oxide Flexible temperature sensor Seebeck coefficient

Sarcopenia in the prognosis of cirrhosis: Going beyond the MELD score

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World Journal of Gastroenterology 2015年第25期21卷 7637-7647页

作者： Hee Yeon kim Jeong won Jang Division of Hepatology Department of Internal Medicine Seoul St. Mary’s Hospital College of Medicine the Catholic University of Korea

Estimating the prognosis of patients with cirrhosis remains challenging, because the natural history of cirrhosis varies according to the cause, presence of portal hypertension, liver synthetic function, and the reversibility of underlying disease. Conventional prognostic scoring systems, including the Child-Turcotte-Pugh score or model for endstage liver diseases are widely used; however, revised models have been introduced to improve prognostic performance. Although sarcopenia is one of the most common complications related to survival of patients with cirrhosis, the newly proposed prognostic models lack a nutritional status evaluation of patients. This is reflected by the lack of an optimal index for sarcopenia in terms of objectivity, reproducibility, practicality, and prognostic performance, and of a consensus definition for sarcopenia in patients with cirrhosis in whom ascites and edema may interfere with body composition analysis. Quantifying skeletal muscle mass using cross-sectional abdominal imaging is a promising tool for assessing sarcopenia. As radiological imaging provides direct visualization of body composition, it is useful to evaluate sarcopenia in patients with cirrhosis whose body mass index, anthropometric measurements, or biochemical markers are inaccurate on a nutritional assessment. Sarcopenia defined by cross-sectional imaging-based muscular assessment is prevalent and predicts mortality in patients with cirrhosis. Sarcopenia alone or in combination with conventional prognostic systems shows promise for a cirrhosis prognosis. Including an objective assessment of sarcopenia with conventional scores to optimize the outcome prediction for patients with cirrhosis needs further research.

关键词： Liver cirrhosis Model for end-stage liverdiseases score Mortality Prognosis Sarcopenia

Reaction mechanism and additional lithium storage of mesoporous MnO_(2) anode in Li batteries

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Journal of Energy Chemistry 2021年第2期30卷 276-284,I0010页

作者： Jaesang Yoon Woosung Choi Taewhan kim Hyunwoo kim Yun Seok Choi Ji Man kim won-Sub Yoon Department of Energy Science Sungkyunkwan UniversitySuwon 16419South Korea Department of Chemistry Sungkyunkwan UniversitySuwon 16419South Korea

Nanostructured transition metal oxides,employed as anode materials for lithium-ion batteries,exhibit a higher capacity than the theoretical capacity based on the conversion *** date,the reasons behind this phenomenon are *** the one-step evolution of anode material for lithium-ion batteries,it is essential to understand the lithium storage reaction mechanism of the anode ***,we provide a detailed report on the lithium storage and release mechanism of MnO2,using synchrotron-based X-ray techniques.X-ray diffraction and X-ray absorption spectroscopy results indicate that during the first discharge,MnO2 is reduced in the order of MnO2→LixMnO2(1

关键词： Mesoporous MnO_(2) Reaction mechanism Electrolyte-derived surface layer Synchrotron-based X-ray techniques Anode Li battery

Effects of TiN film coating on electrochemical behaviors of nanotube formed Ti-xHf alloys

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中国有色金属学会会刊：英文版 2009年第4期19卷 857-861页

作者： Kang LEE won-Gi kim Joo-Young CHO Sang-won EUN Han-Cheol CHOE Department of Dental Materials & Research Center of Nano-Interface Activation for Biomaterials College of DentistryChosun University Department of Applied Advanced Materials Korea Polytechnic Ⅴ Colleges

Ti-xHf(x=10%,20%,30% and 40%,mass fraction) alloys were prepared by arc melting,and the microstructure was controlled for 24 h at 1 000 ℃ in argon *** formation of nanotube was conducted by anodizing on Ti-Hf alloys in 1.0 mol/L H3PO4 electrolytes with small amounts of NaF at room *** then TiN coatings were coated by DC-sputtering on the anodized *** and nanotube morphology of the alloys were examined by field emission scanning electron microscopy(FE-SEM) and X-ray diffractometry(XRD).The corrosion properties of the specimens were examined through potentiodynamic test(potential range from -1 500 to 2 000 mV) in 0.9 % NaCl solution by *** microstructure shows the acicular phase and α' phase with Hf *** amorphous oxide surface is transformed to crystalline anatase *** coated nanotube surface has a good corrosion resistance.

关键词：氮化钛涂层合金制备纳米管电化学行为薄膜包衣 0.9%NaCl溶液扫描电子显微镜微观结构

Permo-Triassic high-pressure metamorphism in the central western Korean Peninsula, and its link to Paleo-Tethyan Ocean closure: Key issues revisited

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Geoscience Frontiers 2018年第5期9卷 1325-1335页

作者： Hyeong Soo kim Sanghoon Kwon Sung won kim M.Santosh Department of Earth and Environmental Sciences Korea University Department of Earth System Sciences Yonsei University Geology Division Korea Institute of Geoscience and Mineral Resources School of Earth Sciences and Resources China University of Geosciences Centre for Tectonics Resources and Exploration Department of Earth Sciences University of Adelaide

Permo-Triassic high-pressure(HP) mafic granulites, together with the Bibong retrogressed eclogite,preserved along the central western Korean Peninsula provide important insights into the Late Permian to Triassic collisional orogeny in northeast Asia. The metamorphic pressureetemperatureetime(P-T-t)paths of these rocks, however, remain poorly constrained and even overestimated, owing to outdated geothermobarometers and inaccurate isopleth techniques. Here we evaluate the metamorphic Pe T conditions of Triassic HP mafic granulites including those in Baekdong, Sinri and Daepan and the Bibong Triassic retrogressed eclogite in the Hongseong area, and the Permo-Triassic Samgot mafic granulite in the Imjingang Belt of the central western Korean Peninsula through the application of modern phase equilibria techniques. The Baekdong and Samgot mafic granulites and the Bibong retrogressed eclogite yield a range of 12.0 -16.0 kbar and 800 -900℃, representing HP granulite facies conditions. The Sinri and Daepan granulites from the Hongseong area show relatively lower grade metamorphic conditions between HP granulite and normal granulite facies, and are characterized by sub-isothermal decompression during exhumation. The similarities in the metamorphic ages and the post-collisional igneous activity from the central western Korean Peninsula indicate that the Triassic ages represent the retrograde stage of the metamorphic Pe T paths. In contrast, the Late Permian metamorphic ages, which are older than protolith ages of the post-collisional igneous rocks, correspond to the possible prograde stage of metamorphism. The P-T-t paths presented in this paper, together with the metamorphic ages and post-orogenic igneous events reported from these areas suggest trace of the subduction, accretion and exhumation history, and indicate a tectonic linkage among the northeast Asian continents during the Paleo-Tethyan Ocean closure.

关键词： HP granulite Retrogressed eclogite Petrology and phase equilibria Metamorphic P-T-t paths Central western Korean Peninsula

Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector

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Nano Research 2021年第6期14卷 1967-1972页

作者： Ui Yeon won Boo Heung Lee Young Rae kim won Tae Kang Ilmin Lee Ji Eun kim Young Hee Lee Woo Jong Yu Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Republic of Korea Center for Integrated Nanostructure Physics Institute for Basic Science(IBS)Suwon16419Republic of Korea

Graphene(Gr)/Si-based optoelectronic devices have attracted a lot of academic attention due to the simpler fabrication processes,low costs,and higher performance of their two-dimensional(2D)/three-dimensional(3D)hybrid interfaces in Schottky junction that promotes electron-hole ***,due to the built-in potential of Gr/Si as a photodetector,the Iph/Idark ratio is often hindered near zero-bias at relatively low illumination *** is a major drawback in self-powered *** this study,we have demonstrated a self-powered van der Waals heterostructure photodetector in the visible range using a Gr/hexagonal boron nitride(h-BN)/Si structure and clarified that the thin h-BN insertion can engineer asymmetric carrier transport and avoid interlayer coupling at the *** dark current was able to be suppressed by inserting an h-BN insulator layer,while maintaining the photocurrent with minimal decrease at near *** a result,the normalized photocurrent-to-dark ratio(NPDR)is improved more than 104 ***,both Iph/Idark ratio and detectivity,increase by more than 104 times at−0.03 V drain *** proposed Gr/h-BN/Si heterostructure is able to contribute to the introduction of next-generation photodetectors and photovoltaic devices based on graphene or silicon.

关键词： graphene hexagonal boron nitride van der Waals heterostructure self-powered Research