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Facile synthesis of fully ordered L10-FePt nanoparticles with controlled Pt-shell thicknesses for electrocatalysis

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Nano Research 2017年第8期10卷 2866-2880页

作者： Yonghoon Hong Hee Jin Kim Daehee Yang Gaehang Lee Ki Min nam Myung-Hwa Jung Young-Min Kim Sang-II choi Won Seok Seo Department of Chemistry Sogang University Seou104107 Republic of Korea Department of Chemistry and Green-Nano Materials Research Center Kyungpook National University Daegu 41566 Repubfic of Korea Korea Basic Science Institute and University of Science and Technology Daejeon 34133 Republic of Korea Department of Chemistry Mokpo National University Jeonnam 58554 Republic of Korea Department of Physics Sogang University Seoul 04107 Republic of Korea Center for Integrated Nanostructure Physics Institute for Basic Science (IBS) Suwon 16419 Repubfic of Korea Department of Energy Science Sungkyunkwan University (SKKU) Suwon 16419 Republic of Korea

We report a simple one-step approach for the synthesis of -4 nm uniform and fully L10-ordered face-centered tetragonal （fct） FePt nanoparticles （NPs） embedded in -60 nm MCM-41 （fct-FePt NPs@MCM-41）. We controlled the Pt-shell thickness of the fct-FePt NPs by treating the fct-FePt NPs@MCM-41 with acetic acid （HOAc） or hydrochloric acid （HC1） under sonicafion, thereby etching the surface Fe atoms of the NPs. The fct-FePt NPs deposited onto the carbon support （fct-FePt NP/C） were prepared by mixing the fct-FePt NPs@MCM-41 with carbon and subsequently removing the MCM-41 using NaOH. We also developed a facile method to synthesize acid-treated fct-FePt NP/C by using a HF solution for simultaneous surface-Fe etching and MCM-41 removal. We studied the effects of both surface-Fe etching and Pt-shell thickness on the electrocatalytic properties of fct-FePt NPs for the methanol oxidation reaction （MOR）. Compared with the non-treated fct-FePt NP/C catalyst, the HOAc-treated and HCl-treated catalysts exhibit up to 34% larger electrochemically active surface areas （ECASAs）; in addition, the HCl-treated fct-FePt NP （with -1.0 nm Pt shell）/C catalyst exhibits the highest specific activity. The HF-treated fct-FePt NP/C exhibits an ECASA almost 2 times larger than those of the other acid-treated fct-FePt NP/C catalysts and shows the highest mass activity （1,435 mA·mgPt^-1, 2.3 times higher than that of the commercial Pt/C catalyst） and stability among the catalysts tested. Our findings demonstrate that the surface-Fe etching for the generation of the Pt shell on fct-FePt NPs and the Pt-shell thickness can be factors for optimizing the electrocatalysis of the MOR.

关键词： FePt face centered tetragonal bimetallic methanol oxidation reaction electrocatalysts

Effects of electrochemical synthetic conditions on surface property and photocatalytic performance of copper and iron-mixed p-type oxide electrodes

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Journal of Materials Science & Technology 2018年第9期34卷 1503-1510页

作者： sun Hee Yoon Dong Suk Han Unseock Kang Seung Yo choi Wubulikasimu Yiming Ahmed Abdel-Wahab Hyunwoong Park Chemical Engineering Program Texas A&M University at Qatar School of Energy Engineering Kyungpook National University Department of Mechanical Engineering Texas A&M University at Qatar

Earth-abundant copper and iron-mixed oxide（CuO/CuFeO_2; CFO） film electrodes are synthesized using an electrochemical deposition（ED） technique at two different ED potentials（-0.36 and-0.66 V vs saturated calomel electrode（SCE）; denoted as ED-1 and ED-2, respectively）. Then, their surface morphologies are compared, and the photo（electro）catalytic activities for the reduction of Cr（VI） are examined in aqueous solutions at pH 7 under simulated sunlight（AM 1.5 G; 100 mW cm（-2））. The degree of the electrical potential applied to the ED process significantly affects the thickness of the synthesized electrode film and the intensity ratio of the diffraction peaks of CuO（111） and CuFeO_2（012）. A 200 μm thick ED-2 sample with a distinct stacking of CuO on CuFeO_2 exhibits a larger broadband absorption spectrum than the 50-μm thick ED-1 with less separate stacking. Furthermore, the ED-2 sample has a higher intensity ratio of the diffraction peaks of CuO（111） and CuFe02（012） than ED-1. As-synthesized ED-2 samples produce larger photocurrents, leading to faster Cr（VI） reduction on the surface under given potential bias（-0.5 V vs SCE）or bias-free conditions. The energy levels（i.e., flatband potential） for the two samples are almost the same（only 10 mV difference）, presumably supposing that the enhanced photoactivity of the ED-2 sample for Cr（VI） reduction is due to the facilitated charge transfer. The time-resolved photoluminescence emission spectra analysis reveal that the lifetime（r） of the charge carriers in the ED-1 sample is 0.103 ns, which decreases to 0.0876 ns in the ED-2. The ED-2 sample synthesized at a high negative potential is expected to contribute greatly to the application of other solar-to-fuel energy conversion fields as a highly efficient electrode material.

关键词： Artificial photosynthesis Solar fuel Delafossites Morphology Charge transfer

Vertically Integrated Thermo-Optic Waveguide Switch Using Optical Polymers

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光学学报 2003年第S1期23卷 359-360页

作者： Ki-Hong Kim Sang-Yung Shin Doo-sun choi Dept. of EECS Korea Advanced Institute of Science and Technology 373-1 Kusong-dong Yusong-gu Daejeon Republic of Korea.Dept. of EECS Korea Advanced Institute of Science and Technology 373-1 Kusong-dong Yusong-gu Daejeon Republic of Korea.Dept of. Intelligence and precision machine Korea Institute of Machinery and Materials 171 Jang-dong Yusong-gu Daejeon Republic of Korea.

We propose and fabricate a vertically integrated thermo-optic waveguide switch. It controls the optical path between two vertically stacked waveguides using the thermo-optic effect of optical polymer. The measured cro... 详细信息

关键词： mode in heat it than Vertically Integrated Thermo-Optic Waveguide Switch Using Optical Polymers of

Inhibitory Mechanisms of Water Extract of Oplopanax elatus on Lipopolysaccharide-lnduced Inflammatory Responses in RAW 264.7 Murine Macrophage Cells

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Chinese Journal of Integrative Medicine 2020年第9期26卷 670-676页

作者： Ki sun Kwon Hyun Lim Yong Soo Kwon Myong Jo Kim Ji Hye Yoo nam Ho Yoo Hyun Pyo Kim College of Pharmacy Kangwon National UniversityChuncheon(24341)Republic of Korea Department of Bio-Resource Sciences Kangwon National UniversityChuncheon(24341)Republic of Korea Bioherb Research Institute Kangwon National UniversityChuncheon(24341)Republic of Korea

Objective:To study the anti-inflammatory action and cellular mechanism of Oplopanax ***:A hot water extract of OE(WOE)was prepared and a major constituent,syringin,was successfully *** content in WOE was found to be 214.0 p.g/g dried plant(w/w).Their anti-inflammatory activities were examined using RAW 264.7 macrophages and a mouse model of croton oil-induced ear ***:In lipopolysaccharide(LPS)-treated RAW 264.7 cells,a mouse macrophage cell line,WOE was found to significantly and strongly inhibit cyclooxygenase-2(COX-2)-induced prostaglandin E2(PGE2)production[half maximal inhibitory concentration(IC50)=135.2μg/mL]and inducible nitric oxide synthase(iNOS)-induced NO production(IC50=242.9μg/mL).In the same condition,WOE was revealed to inhibit NO production by downregulating iNOS expression,mainly by interrupting mitogen activated protein kinases(MAPKs)/activator protein-1(AP-1)*** activation of all three major MAPKs,p38 MAPK,extracellular signal-regulated kinase(ERK),and c-Jun N-terminal kinase,was inhibited by WOE(50-300μg/mL).On the other hand,WOE reduced PGE2 production by inhibiting COX-2 enzyme activity,but did not affect COX-2 expression *** addition,WOE inhibited the production of proinflammatory cytokines such as interleukin-6 and tumor necrosis factor-α.In croton oil-induced ear edema in mice,oral administration of WOE(50-300 mg/kg)dose-dependently inhibited edematic ***:Water extract of OE exhibited multiple anti-inflammatory action mechanisms and may have potential for treating inflammatory disorders.

关键词： Oplopanax elatus Chinese medicine stem syringin anti-inflammation RAW 264.7

Geochemistry of rare earth elements in the mid-late Quaternary sediments of the western Philippine Sea and their paleoenvironmental significance

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Science China Earth Sciences 2014年第4期57卷 802-812页

作者： XU ZhaoKai LI TieGang WAN ShiMing YIN XueBo JIANG FuQing sun HanJie JinYong choi DhongIl LIM Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of Sciences Department of Oceanography Kunsan National University South Sea Institute Korea Institute of Ocean Science and Technology

Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics in- creased during interglacial periods. Changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon （EAWM） as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian materi- al on sedimentation in the western Philippine Sea since 700 ka.

关键词： eolian dust sediment provenance rare earth elements East Asian winter monsoon glacial/interglacial cycle western Philippine Sea

Production of Transgenic Korean Native Cattle Expressing Enhanced Green Fluorescent Protein Using a FIV-Based Lentiviral Vector Injected into MII Oocytes

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Journal of Genetics and Genomics 2013年第1期40卷 37-43页

作者： Yong-Nan Xu Sang-Jun Uhm Bon-Chul Koo Mo-sun Kwon Ji-Yeol Roh Jung-Seok Yang Hyun-Yong choi Young-Tae Heo Xiang-Shun Cui Joon-Ho Yoon Dae-Hwan Ko Teoan Kim nam-Hyung Kim Department of Animal Sciences Chungbuk National University361-763Republic of Korea Department of Animal Science and Biotechnology Sangji Youngseo College220-713Republic of Korea Department of Physiology Catholic University of Daegu School of Medicine712-702Republic of Korea Department of Animal Resources Community KongJu National University340-702Republic of Korea

The potential benefits of generating and using transgenic cattle range from improvements in agriculture to the production of large quantities of pharmaceutically relevant proteins. Previous studies have attempted to produce transgenic cattle and other livestock by pronuclear injection and somatic cell nuclear transfer, but these approaches have been largely ineffective; however, a third approach, lentivirus-mediated transgenesis, has successfully produced transgenic livestock. In this study, we generated transgenic （TG） Korean native cattle using perivitelline space injection of viral vectors, which expressed enhanced green fluorescent protein （EGFP） systemically. Two different types of lentiviral vectors derived from feline immunodeficiency virus （FIV） and human immunodeficiency virus （HIV） carrying EGFP were injected into the perivitelline space of MII oocytes. EGFP expression at 8-cell stage was significantly higher in the FIV group compared to the HIV group （47.5% ± 2.2% v.s. 22.9% 4± 2.9%）. Eight-cell embryos that expressed EGFP were cultured into blastocysts and then transferred into 40 heifers. Ten heifers were successfully impregnated and delivered 10 healthy calves. All of these calves expressed EGFP as detected by in vivo imaging, PCR and Southern blotting. In addition, we established an EGFP-expressing cell line from TG calves, which was followed by nuclear transfer （NT）. Recloned 8-cell embryos also expressed EGFP, and there were no differences in the rates of fusion, cleavage and development between cells derived from TG and non-TG calves, which were subsequently used for NT. These results illustrate that FIV-based lentiviruses are useful for the production of TG cattle. Moreover, our established EGFP cell line can be used for additional studies that involve induced pluripotent stem cells.

关键词： Transgenic cattle Lentiviral vector Perivitelline space injection Enhanced green fluorescent protein

Measurement and evaluation of whole body vibration of agricultural tractor operator

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International Journal of Agricultural and Biological Engineering 2017年第1期10卷 248-255页

作者： Md.Shaha Nur Kabir sun-Ok Chung Yong-Joo Kim nam-Seok sung Soon-Jung Hong Department of Biosystems Machinery Engineering Chungnam National UniversityDaejeon 34134Korea Department of Agricultural and Industrial Engineering Hajee Mohammad Danesh Science and Technology UniversityDinajpur 5200Bangladesh Rural Human Development Center Rural Development AdministrationJeonju 54875Korea

Exposure of whole body vibration(WBV)influences performance,comfort,and long term health risks of tractor ***,measurement and evaluation of WBV parameters should be carried out to find probable effects on the health of tractor *** this study,a system was designed to measure the WBV of agricultural tractor operators and evaluated the hazard risks on operator’s body according to the ISO standards,and implementation of the WBV test in the official testing station was also suggested.A tri-axial accelerometer was employed to measure vibrations transmitted to the seated operator body as a whole through the supporting surface of the buttock on four typical farm roads under different *** vector sum A(8)exposures on the rough tracks(earthen and grassland roads)exceeded the action limits of 0.5 m/s2 at a 10.9 km/h forward speed and reached to the action limit value at a 16.0 km/h forward speed on the concrete *** vector sum of VDV(8)exposures did not exceed the action limits of 9.1 m/s1.75 and was greater on the grassland *** vector sum Sed(8)exposures values exceeded the moderate probability of an adverse health limit of 0.5 MPa on all farm roads at high forward speeds and exceeded the high probability of an adverse health limit of 0.8 MPa on asphalt,concrete,and grassland roads which should be lower than the exposure limit values as suggested by the ISO and EC *** WBV evaluation procedure should be considered for implementation at the official tractor test station,which would response to domestic and international tractor test regulations and improve the market competitiveness.

关键词： agricultural tractor whole body vibration tractor operator driving safety ride comfort test standard health risk

Collision tumor of hepatocellular carcinoma and neuroendocrine carcinoma involving the liver: Case report and review of the literature

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World Journal of Gastroenterology 2016年第41期22卷 9229-9234页

作者： Gyu Ho choi sun Young Ann Soon Il Lee Suk BaeKim Il Han Song Dankook University College of Medicine Cheonan 31116South Korea

Primary hepatic neuroendocrine carcinoma(NEC) with concurrent occurrence of hepatocellular carcinoma(HCC) of the liver is very rare. Only 8 cases have been reported in the literature. Concurrent occurrence of HCC and NEC in the liver is classified as combined type or collision type by histological distributional patterns; only 2 cases have been reported. Herein, we report a case of collision type concurrent occurrence of HCC and NEC, in which primary hepatic NEC was in only a small portion of the nodule, which is different from the 2 previously reported cases. A 72-year-old male with chronic hepatitis C was admitted to our hospital for a hepatic mass detected by liver computed tomography(CT) at another clinic. Because the nodule was in hepatic segment 3 and had proper radiologic findings for diagnosis of HCC, including enhancement in the arterial phase and wash-out in the portal and delay phases, the patient was treated with laparoscopic left lateral sectionectomy. The pathology demonstrated that the nodule was 2.5 cm and was moderately differentiated HCC. However, a 3 mm-sized focal neuroendocrine carcinoma was also detected on the capsule of the nodule. The tumor was concluded to be a collision type with HCC and primary hepatic NEC. After the surgery, for follow-up, the patient underwent a liver CT every 3 mo. Five multiple nodules were found in the right hepatic lobe on the follow-up liver CT 6 mo post-operatively. As the features of the nodules in the liver CT and MRI were different from that of HCC, a liver biopsy was performed. Intrahepatic recurrent NEC was proven after the liver biopsy, which showed the same pathologic features with the specimen obtained 6 mo ago. Palliative chemotherapy with a combination of etoposide and cisplatin has been administered for 4 months, showing partial response.

关键词： Collision tumor Hepatocellular carcinoma Neuroendocrine carcinoma Chronic hepatitis C

Dual function of a high-contrast hydrophobic-hydrophilic coating for enhanced stability of perovskite solar cells in extremely humid environments

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Nano Research 2017年第11期10卷 3885-3895页

作者： Jin sun Yoo Gill Sang Han Seongha Lee Min Cheol Kim Mansoo choi Hyun Suk Jung Jung-Kun Lee School of Advanced Materials Science amp Engineering Sungkyunkwan University Suwon 440-746 Republic of Korea Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical and Aerospace Engineering Seoul National University Seoul 08826 Republic of Korea

In spite of a continuous increase in their power conversion efficiency （PCE） and an economically viable fabrication process,organic-inorganic perovskite solar cells （PSCs） pose a significant problem when used in practical applications：They show fast degradation of the PCE when exposed to very humid *** this study,the stability of PSCs under very humid conditions is greatly enhanced by coating the surface of the PSC devices with a multi-layer film consisting of ultrahydrophobic and relatively hydrophilic layers.A hydrophobic composite of poly（methyl methacrylate）（PMMA）,polyurethane （PU）,and SiO2 nanoparticles successfully retards the water molecules from very humid ***,the hydrophilic layer with moderately PMMA captures the residual moisture within the perovskite layer;subsequently,the perovskite layer *** dual function of the coating film keeps the PCE of PSCs at 17.3% for 180 min when exposed to over 95% humidity.

关键词： perovskite solar cell stability surface coating ultrahydrophobic self-recovery