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Acta Geologica Sinica(English Edition) 2003年第1期77卷 116-124页

作者： LEE hyun koo Depatment of Geology Chungnam National University 220 Kungdong Yuseong Ku Taejon 305-764 Republic of Korea

A comprehensive contrast of ore-forming geological background and ore-forming fluid features, especially fluid ore-forming processes, has been performed between the Tianmashan and the Datuanshan ore deposits in Tongling, Anhui Province. The major reasons for the formation of the stratabound skarn Au-S ore deposit in Tianmashan and the stratabound skarn Cu ore deposit in Datuanshan are analyzed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au-bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the ore-forming fluids in Tianmashan are dominantly magmatic ones at the oxide and sulfide stages, but those with high content of Cu in Datuanshan are mainly groundwater fluids. In addition, differences in compositional evolution and physicochemical condition variation of the ore-forming fluids result in gradual dispersion

关键词： fluid inclusion fluid ore-forming process contrast in fluid metallogeny Au-S ore deposit Cu ore deposit magmatic fluid groundwater fluid Tongling Anhui Province

Extracellular Polysaccharides Matrix—An Often Forgotten Virulence Factor in Oral Biofilm Research

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International Journal of Oral Science 2009年第4期1卷 229-234页

作者： hyun koo Marlise I.Klein Eastman Department of Dentistry and Center for Oral Biology University of Rochester Medical CenterUSA

Oral diseases related to dental biofilms continue to afflict the majority of the world＇s population. Among them, dental caries continues to be the single most prevalent and costly oral infectious disease （Marsh, 2003; Dye et al., 2007）. Dental caries results from the interaction of specific bacteria with constituents of the diet within a dental biofilm known as plaque （Bowen, 2002）. Sucrose is considered to be the ＂arch criminal＂ from the dietary aspect because it serves as a substrate for synthesis of extracellular （EPS） and intracellular （IPS） polysaccharides in dental biofilm and is also fermentable （Bowen, 2002）.

关键词： An Often Forgotten Virulence Factor in Oral Biofilm Research Extracellular Polysaccharides Matrix oral

Biofilm three-dimensional architecture influences in situ pH distribution pattern on the human enamel surface

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International Journal of Oral Science 2017年第2期9卷 74-79页

作者： Jin Xiao Anderson T Hara Dongyeop Kim Domenick T Zero hyun koo Geelsu Hwang Eastman Institute for Oral Health University of Rochester Medical Center Department of Cariology Operative Dentistry and Dental Public HealthOral Health Research InstituteIndiana University School of Dentistry Biofilm Research Laboratories Levy Center for Oral HealthDepartment of Orthodontics and Divisions of Pediatric Dentistry & Community Oral HealthSchool of Dental MedicineUniversity of Pennsylvania

To investigate how the biofilm three-dimensional(3D) architecture influences in situ pH distribution patterns on the enamel surface. Biofilms were formed on human tooth enamel in the presence of 1% sucrose or 0.5% glucose plus 0.5% fructose. At specific time points, biofilms were exposed to a neutral pH buffer to mimic the buffering of saliva and subsequently pulsed with 1% glucose to induce re-acidification. Simultaneous 3D pH mapping and architecture of intact biofilms was performed using two-photon confocal microscopy. The enamel surface and mineral content characteristics were examined successively via optical profilometry and microradiography analyses. Sucrose-mediated biofilm formation created spatial heterogeneities manifested by complex networks of bacterial clusters(microcolonies). Acidic regions(pH<5.5) were found only in the interior of microcolonies,which impedes rapid neutralization(taking more than 120 min for neutralization). Glucose exposure rapidly re-created the acidic niches, indicating formation of diffusion barriers associated with microcolonies structure. Enamel demineralization(white spots),rougher surface, deeper lesion and more mineral loss appeared to be associated with the localization of these bacterial clusters at the biofilm-enamel interface. Similar 3D architecture was observed in plaque-biofilms formed in vivo in the presence of sucrose. The formation of complex 3D architectures creates spatially heterogeneous acidic microenvironments in close proximity of enamel surface, which might correlate with the localized pattern of the onset of carious lesions(white spot like) on teeth.

关键词： biofilms demineralization dental caries exopolysaccharides microcolonies pH microenvironments plaque Streptococcus mutans

Lubrication properties of silver-palladium alloy prepared by ion plating method for high temperature stud bolt

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 12-16页

作者： Jung-Dae KWON Sunghun LEE koo-hyun LEE Jong-Joo RHA Kee-Seok NAN Se-Hun KWON Materials Processing Division Korea Institute of Materials Science Changwon Gyeongnam 641-831 Korea National Core Research Center for Hybrid Materials Solution Pusan National University

As a solid lubricant, silver-palladium (Ag-Pd) alloy coating was investigated for the application to high temperature stud bolt. A glue layer nickel (Ni) film was deposited on the surface of the hex bolt sample and then Ag-Pd alloy coating was performed on it using ion plating method. The friction coefficient of Ag-Pd alloy film coated bolt was lower than that of N-5000 oil coated bolt by the result of axial force measurement. The cyclic test of heat treatment was conducted to evaluate the durability of Ag-Pd alloy film coated bolt. In a cycle, sample was assembled into the block using torque wrench, followed by heating and disassembling. It was not successful to disassemble the N-5000 oil coated bolt from the block after only one cycle. However, the Ag-Pd alloy film coated bolt was able to be disassembled softly till 12 cycles.

关键词： solid lubricant silver-palladium alloy ion plating

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

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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

Detection of early gastric cancer using hydro-stomach CT:Blinded vs unblinded analysis

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World Journal of Gastroenterology 2011年第8期17卷 1051-1057页

作者： Ki Jeong Park Min Woo Lee Ji hyun koo Yulri Park Heejung Kim Dongil Choi Soon Jin Lee Department of Radiol-ogy and Center for Imaging Science Samsung Medical Center Sungkyunkwan University School of Medicine

AIM:To evaluate the difference in diagnostic performance of hydro-stomach computed tomography(CT) to detect early gastric cancer(EGC) between blinded and unblinded analysis and to assess independent factors affecting visibility of cancer ***:Two radiologists initially blinded and then unblinded to gastroscopic and surgical-histological findings independently reviewed hydro-stomach CT images of 110 patients with single *** graded the visibility of cancer foci for each of three gastric segments(upper,middle and lower thirds) using a 4-point scale(1:definitely absent,2:probably absent,3:probably present,and 4:definitely present).The sensitivity and specificity for detecting an EGC were *** and interobserver agreements were *** visibility of an EGC was evaluated with regard to tumor size,invasion depth,gastric segments,histological type and gross morphology using univariate and multivariate ***:The respective sensitivities and specificities [reviewer 1:blinded,20%(22/110) and 98%(215/220);unblinded,27%(30/110) and 100%(219/220)/reviewer 2:blinded,19%(21/110) and 98%(216/220);unblinded,25%(27/110) and 98%(215/220)] were not significantly *** intraobserver agreements were good(weighted κ = 0.677 and 0.666),interobserver agreements were fair(blinded,0.371) or moderate(unblinded,0.558).For both univariate and multivariate analyses,the tumor size and invasion depth were statistically significant factors affecting ***:The diagnostic performance of hydrostomach CT to detect an EGC was not significantly different between blinded and unblinded *** tumor size and invasion depth were independent factors for visibility.

关键词： Stomach neoplasm Computed tomography Water Early detection of cancer Sensitivity

Nuclear and chloroplast genome diversity revealed by low-coverage whole-genome shotgun sequence in 44 Brassica oleracea breeding lines

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Horticultural Plant Journal 2021年第6期7卷 539-551页

作者： Sampath Perumal Nomar Espinosa Waminal Jonghoon Lee hyun-Jin koo Boem-soon Choi Jee Young Park Kyounggu Ahn Tae-Jin Yang Department of Agriculture Forestry and BioresourcesPlant Genomics and Breeding Instituteand Research Institute of Agriculture and Life SciencesCollege of Agriculture and Life SciencesSeoul National UniversitySeoul 08826Republic of Korea Global Institute for Food Security University of Saskatchewan421 Downey RoadSaskatoonSK S7N 4L8Canada Agriculture and Agri-Food Canada 107 Science PlaceSaskatoon S7N 0X2Canada Chromosome Research Institute Department of Life ScienceSahmyook UniversitySeoul 01795Republic of Korea Joeun Seeds.Co. LtdGoesan-GunChungcheongbuk-Do 367-833Republic of Korea Phyzen Genomics Institute 13Seongnam-daero 331beon-gilBundang-guSeongnam-siGyeonggi-do 13558Republic of Korea

Whole-genome shogun sequence(WGS)data generated by next-generation sequencing(NGS)platforms are a valuable resource for crop *** produced 5–6×WGS coverage of 44 Brassica oleracea breeding lines representing seven subspecies/morphotypes:cabbage,broccoli,cauliflower,kailan,kale,Brussels sprout,and kohlrabi to systematically evaluate the nuclear and chloroplast(Cp)diversity in the 44 *** breeding *** then exploited the impact of low-coverage NGS by evaluating nuclear genome diversity and assembly,annotation of complete chloroplast(Cp)genomes and 45 S nuclear ribosomal DNA(45S nrDNA)sequences,and copy number variation for major *** genome diversity analysis has revealed a total of 496463 SNPs and 37493 indels in the nuclear genome across the 44 ***,some SNPs showed subspecies enrichment at certain chromosomal *** assembly of complete Cp genomes contained 153361–153372 bp with 37 variants including SNPs and *** 45S nrDNA transcription unit was 5802 bp long with a total of 31 SNPs from the 44 *** phylogenetic tree inferred from the nuclear and Cp genomes coincided and clustered broccoli,cauliflower,and kailan in one group and cabbage,Brussels sprout,kale,and kohlrabi in another *** morphotypes diverged during the last 0.17 million *** Cp genome diversity reflected the unique cytoplasm of each subspecies,and revealed that the cytoplasm of many breeding lines was replaced and intermingled via inter-subspecies crosses during the breeding process *** polymorphic Cp markers provide a classification system for the cytoplasm types in ***,copy numbers of major transposable elements(TEs)showed high diversity among the 44 accessions,indicating that many TEs have become active ***,we demonstrated a comprehensive utilization of low-coverage NGS data and might shed light on the genetic diversity and evolution of diverse *** morphotypes.

关键词： Brassica oleracea subspecies Chloroplast genome Nuclear ribosomal DNA Genetic diversity Phylogeny

Influences of trans-trans farnesol,a membrane-targeting sesquiterpenoid,on Streptococcus mutans physiology and survival within mixed-species oral biofilms

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International Journal of Oral Science 2011年第2期3卷 98-106页

作者： Jae-Gyu Jeon Santosh Pandit Jin Xiao Stacy Gregoire Megan L. Falsetta Marlise I. Klein hyun koo Department of Preventive Dentistry School of Dentistry Chonbuk National University Jeonju 561756 Republic of Korea Institute of Oral Bioscience and BK 21 program Chonbuk National University Jeonju 561756 Republic of Korea Center for Oral Biology University of Rochester Medical Center Rochester New York 14620 USA Department of Microbiology and Immunology University of Rochester Medical Center Rochester New York 14620 USA State Key Laboratory of Oral Diseases Sichuan University Chengdu 610041 China

Trans-trans farnesol （tt-farnesol） is a bioactive sesquiterpene alcohol commonly found in propolis （a beehive product） and citrus fruits, which disrupts the ability of Streptococcus mutans （S. mutans） to form virulent biofilms. In this study, we investigated whether tt-farnesol affects cell-membrane function, acid production and/or acid tolerance by planktonic cells and biofilms of S. mutans UA159. Furthermore, the influence of the agent on S. mutans gene expression and ability to form biofilms in the presence of other oral bacteria （Streptococcus oralis （S. oralis） 35037 and Actinomyces naeslundii （.4. naeslundil） 12104） was also examined. In general, tt-farnesol （1 mmol-L-1） significantly increased the membrane proton permeability and reduced glycolytie activity of S. mutans in the planktonic state and in biofilms （P〈0.05）. Moreover, topical applications of 1 mmol-L＂l tt-farnesol twice daily （1 min exposure/treatment） reduced biomass accumulation and prevented ecological shifts towards S. mutans dominance within mixed-species biofilms after introduction of 1% sucrose. S. oralis （a non-cariogenie organism） became the major species after treatments with tt-farnesol, whereas vehicle-treated biofilms contained mostly S. mutans （〉90% of total bacterial population）. However, the agent did not affect significantly the expression of S. mutans genes involved in acidogenicity, acid tolerance or polysaccharide synthesis in the treated biofilms. Our data indicate that tt-farnesoi may affect the competi- tiveness of S. mutans in a mixed-species environment by primarily disrupting the membrane function and physiology of this bacterium. This naturally occurring terpenoid could be a potentially useful adjunctive agent to the current anti-biofilm/anti-caries chemotherapeutic strategies.

关键词： trans-trans farnesol acid production acid tolerance biofilms proton permeability Streptococcus mutans

Silver-palladium alloy deposited by DC magnetron sputtering method as lubricant for high temperature application

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中国有色金属学会会刊：英文版 2009年第4期19卷 1001-1004页

作者： Jung-Dae KWON Sung-Hun LEE koo-hyun LEE Jong-Joo RHA Kee-Seok NAM Sang-Hoon CHOI Dong-Min LEE Dong-Il KIM Materials Processing Division Korea Institute of Materials Science Technology Research & Development Institute Korea Plant Service and Engineering

The silver-palladium(Ag-Pd) alloy coating as a solid lubricant was investigated for its application to the high temperature stud bolts used in nuclear power plants.A hex bolt sample was prepared in the following steps:1) bolt surface treatment using alumina grit blasting for cleaning and increasing the surface area;2) nickel(Ni) film coating as a glue layer on the surface of the bolt;and 3) Ag-Pd alloy coating on the Ni *** films were deposited by using a direct current(DC) magnetron sputtering *** thickness and composition of the Ag-Pd alloy film have effect on the friction coefficient,which was determined using axial force measurement.A 500 nm-thick Ag-Pd(80-20,molar ratio) alloy film has the lowest friction coefficient of 0.109.A cyclic test was conducted to evaluate the durability of bolts coated with either the Ag-Pd(80-20) alloy film or N-5000 *** a cycle,the bolts were inserted into a block using a torque wrench,which was followed by heating and *** only one cycle,it was not possible to remove the bolts coated with the N-5000 oil from the ***,the bolts coated with the Ag-Pd(80-20) alloy could be easily removed up until 15 cycles.

关键词：银钯合金直流电高温润滑剂沉积磁控溅射法固体润滑涂层高温螺栓

Colonoscopy-induced ischemic colitis in patients without risk factors

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World Journal of Gastroenterology 2014年第13期20卷 3698-3702页

作者： Sang Ok Lee Sae Hee Kim Sung Hee Jung Chan Woong Park Min Ji Lee Jin A Lee hyun Cheol koo Anna Kim hyun-Young Han Dong-Wook Kang Division of Gastroenterology Department of Internal MedicineEulji University College of MedicineEulji University HospitalDaejeon 302-779South Korea Department of radiology Eulji University College of MedicineEulji University HospitalDaejeon 302-779South Korea Department of pathology Eulji University College of MedicineEulji University HospitalDaejeon 302-779South Korea

Ischemic colitis is the most common form of intestinal *** is a condition that is commonly seen in the elderly and among individuals with risk factors for *** predisposing conditions for ischemic colitis are major vascular occlusion,small vessel disorder,shock,some medications,colonic obstructions and hematologic *** colitis following colonoscopy is ***,we report two cases of ischemic colitis after a routine screening colonoscopy in patients without risk factors for ischemia.

关键词： Ischemic colitis Colonoscopy Hematochezia