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Friction 2023年第7期11卷 1292-1306页

作者： Kuk-jin SEO hyun-Joon KIM Dae-Eun KIM Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Precision Mechanical Engineering Kyungpook National UniversitySangju 37224Republic of Korea Department of Advanced Science and Technology Convergence Kyungpook National UniversitySangju 37224Republic of Korea

This work shows that a soft,thin film comprising randomly aligned carbon nanotubes(CNTs)can reduce surface wear more effectively than a homogeneous thin film because of enhanced elastic recoverability and contact stress relief originating from its mesh *** investigate the wear characteristics of the mesh structure compared to those of the homogeneous thin film,multi-walled CNTs(MWCNTs)and diamond-like carbon(DLC)thin films were prepared to conduct nanoscale tribological experiments using the atomic force microscopy(AFM).The MWCNT thin film showed unmeasurably low wear compared with the DLC thin film under a certain range of normal *** demonstrate the wear reduction mechanism of the MWCNT thin film,its indentation and frictional behaviors were *** indentation behavior of the MWCNT thin film revealed repetitive elastic deformation with a wide strain range and a significantly lower elastic modulus than that of the DLC thin *** permanent deformation of the MWCNT thin film was observed through frictional experiments under relatively high normal load *** results are expected to provide insights into the design of highly wear-resistant surfaces using nanostructures.

关键词： carbon nanotube(CNT) thin film wear friction elastic recovery

Adhesive ginsenoside compound K patches for cartilage tissue regeneration

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Regenerative Biomaterials 2023年第1期10卷 1442-1450页

作者： Jun-Ho Yang hyun Ho Shin Donghyeon Kim Ji hyun Ryu Eun-Jung jin Department of Biological Sciences College of Health SciencesWonkwang UniversityIksanJeonbuk 54538South Korea Department of Chemical Engineering Wonkwang UniversityIksanJeonbuk 54538South Korea Department of Carbon Convergence Engineering Wonkwang UniversityIksanJeonbuk 54538South Korea Integrated Omics Institute Wonkwang UniversityIksanJeonbuk 54538South Korea

Biomaterial-based drug delivery systems have been developed to expedite cartilage regeneration;however,challenges related to drug recovery,validation,and efficient drug delivery *** instance,compound K(CK)is a major metabolite of ginsenosides that is known to protect against joint degeneration by inhibiting the production of inflammatory cytokines and the activation of immune ***,its effects on cartilage degradation and tissue regeneration remain ***,tissue-adhesive drug delivery depots that stably adhere to cartilage defects are required for CK *** this study,CK-loaded adhesive patches were reported to seal cartilage defects and deliver CK to defect sites,preventing cartilage degradation and accelerating cartilage tissue *** patches are stable and suitable for application in surgical procedures under physiological conditions and show excellent adhesiveness to cartilage *** addition,there were no significant differences in the adhesive polymeric networks before and after CK ***-loaded hydrocaffeic acid-conjugated chitosan patches significantly inhibited the stimulation of cartilage-degrading enzymes and apoptosis in osteoarthritic cartilage by releasing CK in cartilage ***,the NFkB signaling pathway of released CK from the adhesive patches in the treatment of osteoarthritis is ***,the CK-loaded adhesive patches are expected to significantly contribute to cartilage regeneration.

关键词： ginsenoside compound K adhesive patch drug delivery hydrocaffeic acid-conjugated chitosan osteoarthritis

Acceleration of aging behavior and improvement of mechanical properties of extruded AZ80 alloy through(10–12) twinning

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Journal of Magnesium and Alloys 2023年第2期11卷 671-683页

作者： hyun Ji Kim Ye jin Kim Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

The effects of pre-existing {10–12} extension twins on the precipitation behavior of an extruded AZ80 material during aging and on its mechanical properties after peak aging are investigated. The material containing {10–12} twins-which are formed by compression before aging(twinned material)-has a finer grain size and higher dislocation density than the extruded material. Although the peak hardnesses of the twinned and extruded materials are almost the same, the time to reach the peak hardness is considerably shorter in the former material than in the latter(4 h and 24 h, respectively). In the twinned material, the high dislocation density of the {10–12} twins promotes continuous precipitation, which results in the formation of numerous fine Mg17Al12precipitates within the twins in the early stage of *** formation of these continuous precipitates reduces the driving force for discontinuous precipitation, which consequently suppresses the formation and growth of coarse Mg17Al12precipitates at the grain boundaries. Despite its shorter peak-aging time, the 4 h-peak-aged twinned material shows higher tensile strength and elongation than the 24 h-peak-aged extruded material. These higher mechanical properties of the former material are attributed primarily to the presence of more abundant fine continuous precipitates, which are effective in strengthening the material, and less abundant coarse discontinuous precipitates, which can act as crack initiation sites. These results demonstrate that the introduction of {10–12} twins into wrought Mg–Al-based alloys can accelerate the Mg17Al12precipitation kinetics considerably and improve the strength and ductility of the peak-aged alloys simultaneously.

关键词： AZ80 alloy Twin Aging Precipitation Tensile properties

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Gene expression profiling reveals sequential changes in gastric tubular adenoma and carcinoma in situ

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World Journal of Gastroenterology 2005年第13期11卷 1937-1945页

作者： Chang-Hee Lee Seung-hyun Bang Seung-koo Lee Kyu-Young Song In-Chul Lee Asan Institute for Life Sciences Department of Biochemistry Department of Pathology

AIM: To analyze the expression profiles of premalignant and/or preclinical lesions of gastric ***: We analyzed the expression profiles of normal gastric pit, tubular adenoma and carcinoma in situ using microdissected cells from routine gastric biopsies. For the DNA microarray analysis of formalin-fixed samples,we developed a simple and reproducible RNA extraction and linear amplification procedure applying two polymerasebinding sites. The amplification procedure took only 8 h and yielded comparable DNA microarray data between formalin-fixed tissues and unfixed ***: In comparison with normal pit, adenoma/carcinoma showed 504 up-regulated and 29 down-regulated genes at the expected false significance rate 0.15%. The differential expression between adenoma and carcinoma in situ was subtle: 50 and 22 genes were up-, and down-regulated in carcinomas at the expected false significance rate of 0.61%, respectively. Differentially expressed genes were grouped according to patterns of the sequential changes for the 'tendency analysis' in the gastric mucosaadenoma-carcinoma ***: Groups of genes are shown to reflect the sequential expression changes in the early carcinogenic steps of stomach cancer. It is suggested that molecular carcinogenic pathways could be analyzed using routinely processed biopsies.

关键词： Premalignant lesion Predinical lesion Gastric cancer

Pharmacokinetics and tissue distribution of a novel PDE5 inhibitor,SK-3530,in rats

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Acta Pharmacologica Sinica 2007年第8期28卷 1247-1253页

作者： Hye-hyun YOO Nam-sun KIM Guang-jin Im Dong-hyun KIM Bioanalysis and Biotransformation Research Center Korea Institute of Science & Technology Seoul 136-791Korea Life Science RD Center SK ChemicalsGyeonggi-do 440-300Korea

Aim:To investigate the pharmacokinetic profile and tissue distribution of a novelphosphodiesterase type 5 inhibitor,5-ethyl-2-{5-[4-（2-hydroxy-ethyl）-piperazine-1-sulfonyl]-2-propoxy-phenyl}-7-propyl-3,5-dihydro-pyrrolo（3,2-d）pyrimidin-4-one（SK-3530）,in rats after administration of the14C-labeled ***:The pharmacokinetic parameters of SK-3530 were measured based on the totalradioactivity and parent SK-3530 concentration in rat plasma after intravenousand oral *** tissue distribution of total radioactivity after a singleoral administration of[14C]SK-3530 at a dose of 40 mg/kg was *** protein binding rates of SK-3530 were assessed by in vitro and ex ***:The total radioactivity profiles showed linear *** maximum plasma concentration and area under the curve of the parent SK3530were 10%-20% compared to those of the total *** the oral admin-istration of[14C]SK-3530,the radioactivity was widely distributed in all tissues,and the tissue/plasma ratio of the radioactivity 1 h after administration was calcu-lated as 0.5-2.6 with the exception of excretory organs.A relatively high penetra-tion was shown in the adrenal glands,liver,and *** vitro and ex vivo plasmaprotein binding assay by ultrafiltration showed a considerably high binding rateof more than 97%.Conclusion:SK-3530 was relatively well absorbed in the gas-trointestinal tract and showed linear pharmacokinetics over the investigated ***-3530 had low oral bioavailability due to a high,first-pass metabolism.

关键词： SK-3530 PDE5 inhibitor pharmacokinetics tissue distribution rats

What is the appropriate strategy for diagnosing NAFLD using ultrasonography in obese children?

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World Journal of Pediatrics 2017年第3期13卷 248-254页

作者： Jee hyun Lee Su jin Jeong Department of Pediatrics Ansan HospitalKorea University Medical CenterCollege of MedicineKorea University Department of Pediatrics Bundang CHA Medical CenterCHA University School of MedicineKorea

Background:The aim of this study is to identify obese children who are candidates for a potential diagnosis of non-alcoholic fatty liver disease (NAFLD).Methods:We enrolled 242 obese children (122 boys and 120 girls) aged 7-16 years who were examined with abdominal ultrasonography in our pediatric obesity *** compared patients in the normal group with those in the NAFLD group (mild disease,moderate to severe disease) and identified the optimal anthropometric parameters among height,weight,body mass index (BMI),waist circumference,hip circumference,waist to height ratio (WHtR),and waist to hip ratio to predict NAFLD using a receiver operating characteristic curve *** also investigated risk factors associated with NAFLD for the anthropometric parameters and the biochemical model using logistic ***:The high-and low-risk groups for hepatic steatosis relative to a WHtR of 0.56 as the standard point showed significant differences in hepatic steatosis severity grade (P0.56 (2.25,1.05-4.81),and waist circumference >90th percentile (20.22,9.21-44.36) in the anthropometric parameter model and elevated alanine aminotransferase levels (boys >25.8 U/L,girls >22.1 U/L) (6.93,2.52-19.03),hypertriglyceridemia (>110 mg/dL) (3.80,1.23-11.75),and triglyceride to HDL cholesterol ratio >3 (9.23,2.95-8.83) in the biochemical parameter ***:A diagnostic approach to hepatic steatosis is recommended as part of the proper screening and stratification of risk factors in obese *** is a simple and convenient method of effectively identifying obese children who are candidates for hep

关键词： hepatic steatosis non-alcoholic fatty liver disease obesity waist-to-height ratio

Relationship between early structural changes at cornea incision sites and surgical outcomes after phacoemulsification

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International Journal of Ophthalmology(English edition) 2019年第7期12卷 1139-1145页

作者： Kyung hyun jin Tae Gi Kim Department of Ophthalmology Kyung Hee University Medical Center Kyung Hee University Seoul 02447 Korea Department of Ophthalmology Kyung Hee University Hospital at Gangdong Kyung Hee University Seoul 05278 Korea

AIM: To assess the early structural changes at clear corneal cataract incision sites and surgical outcomes using anterior segment optical coherence tomography(AS-OCT).METHODS: We evaluated 80 eyes of 59 patients who underwent phacoemulsification with a clear corneal incision. All incisions were evaluated 1 wk, 1, and 3 mo postoperatively using AS-OCT and analyzed regarding angle, length of the incision, maximal corneal thickness at the incision, and if present, corneal endothelial gap length and incision gap area. The patients were divided into two groups according to whether or not an endothelial gap was present at 1 wk postoperatively(endothelial gap, group 1;no endothelial gap, group 2). We analyzed the difference in patient and surgical factors between the two groups, and compared the surgical outcome and the refractive ***: An endothelial gap was observed in 56(70.0%) of 80 eyes at 1 wk postoperatively but not at 3 mo postoperatively. The mean patient age was significantly higher in group 1 than in group 2. The longer the length of the corneal incision and the steeper the incision angle, the greater the length and area of the endothelial gap. In group 1, the mean change in mean keratometry of the anterior cornea was significantly greater than in group 2, and the spherical equivalent(SE) and mean numerical error indicated significant myopic changes at 1 wk postoperatively. CONCLUSION: The risk of an endothelial gap increases with patient age and a long corneal incision and steep incision angle. The presence of an endothelial gap aftersurgery may affect the early postoperative corneal curvature and SE.

关键词： corneal incision structure phacoemulsification corneal curvature corneal endothelial gap anterior segment optical coherence tomography

Enhanced refolding of lysozyme with imidazolium-based room temperature ionic liquids: Effect of hydrophobicity and sulfur residue

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Science China Chemistry 2012年第8期55卷 1657-1662页

作者： BAE Sang-Woo CHANG Woo-jin koo Yoon-Mo HA Sung Ho Department of Biological Engineering Inha University Incheon 402-751 Republic of Korea Department of Mechanical Engineering School of Freshwater Sciences University of Wisconsin-Milwaukee Milwaukee WI 53201-0413 USA Department of Chemical Engineering and Nano-Bio Technology Hannam University Daejeon 305-811 Republic of Korea

The expression of recombinant proteins in microorganism frequently leads to the formation of insoluble aggregates, inclusion bodies （IBs）. Thus, the additional in vitro protein refolding process is required to convert inactive IBs into water-soluble active proteins. This study investigated the effect of sulfur residue and hydrophobicity of imidazolium-based room temperature ionic liquids （RTILs） on the refolding of lysozyme as a model protein in the batch dilution method which is the most commonly used refolding method. When lysozyme was refolded in the refolding buffer containing [BF4]-based RTILs with a systematic variety of alkyl chain on cations varying from two to eight, less hydrophobic imidazolium cations having shorter alkyl chains were effective to facilitate lysozyme refolding. Compared to the conventional refolding buffer, 2 times higher lysozyme re- folding yield was obtained in l-ethyl-3-methylimidazolium tetrafluoroborate （[EMIM][BF4]） containing refolding buffer. The refolding yield of lysozyme was even more increased by 2.5 times when 1-butyl-3-methylimidazolium methylsulfate （[BMIM][MS]） containing sulfur residue on anion was used. The sulfur residue in [BMIM][MS] is supposed to improve the refolding yield of lysozyme which has 4 intrarnolecular disulfide bonds. For dilution-based refolding of lysozyme, the opti- mum concentrations of RTILs in refolding buffer were found to be 1.0 M [EMIM][BF4] and 0.5 M [PMIM][MS], respectively. The optimum temperate for dilution-based refolding of lysozyme with RTILs was 4 ℃.

关键词： protein refolding room temperature ionic liquid dilution refolding lysozyme hydrophobicity sulfur

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Switching-on of serotonergic calcium signaling in activated hepatic stellate cells

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World Journal of Gastroenterology 2011年第2期17卷 164-173页

作者： Kyu-Sang Park Pyo-jin Sin Dong Hyeon Lee Seung-Kuy Cha Min-Jeong Kim Na-hyun Kim Soon-koo Baik Seong-Woo Jeong In Deok Kong Department of Physiology and Institute of Lifelong Health Yonsei University Wonju College of Medicine Department of Physiology College of MedicinePochon CHA University Department of Basic Nursing Science Keimyung University College of Nursing Department of Internal Medicine Yonsei University Wonju College of Medicine

AIM:To investigate serotonergic Ca 2+ signaling and the expression of 5-hydroxytryptamine(5-HT) receptors,as well as Ca 2+ transporting proteins,in hepatic stellate cells(HSCs) . METHODS:The intracellular Ca 2+ concentration([Ca 2+ ]i) of isolated rat HSCs was measured with a fluorescence microscopic imaging *** PCR was per-formed to determine the transcriptional levels of 5-HT receptors and endoplasmic reticulum(ER) proteins involved in Ca 2+ storage and release in cultured rat HSCs. RESULTS:Distinct from quiescent cells,activated HSCs exhibited[Ca 2+ ]i transients following treatment with 5-HT,which was abolished by U-73122,a phospholipase C *** of 5-HT2A and 5-HT2B receptors,but not 5-HT3,was prominent during trans-differentiation of *** with ritanserin,a 5-HT2 antagonist,inhibited[Ca 2+ ]i changes upon application of *** of type 1 inositol-5'-triphosphate receptor and type 2 sarcoplasmic/endoplasmic reticulum Ca 2+ ATPase were also increased during activation of HSCs and serve as the major isotypes for ER Ca 2+ storage and release in activated *** 2+ binding chaperone proteins of the ER,including calreticulin,calnexin and calsequestrin,were up-regulated following activation of HSCs. CONCLUSION:The appearance of 5-HT-induced[Ca 2+ ]i response accompanied by upregulation of metabotropic 5-HT2 receptors and Ca 2+ transporting/chaperone ER proteins may participate in the activating process of HSCs.

关键词： Hepatic stellate cells 5-hydroxytryptamine Intracellular Ca 2+ transient Sarcoplasmic/endoplasmic reticulum Ca 2+ ATPase Inositol-5’-triphosphate receptor Endoplasmic reticulum chaperone

Web Tension Regulation of Multispan Roll-to-Roll System using Integrated Active Dancer and Load Cells for Printed Electronics Applications

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 229-239页

作者： ZUBAIR Muhammad PONNIAH Ganeshthangaraj YANG Young jin CHOI Kyung hyun Department of Mechatronics Engineering Jeju National University

The mass production of primed electronics can be achieved by roll-to-roll（R2R） printing system, so highly accurate web tension is required that can minimize the register error and keep the thickness and roughness of printed devices in limits. The web tension of a R2R system is regulated by the use of integrated load cells and active dancer system for printed electronics applications using decentralized multi-input-single-output（MISO） regularized variable learning rate backpropagation artificial neural networks. The active dancer system is used before printing system to reduce disturbances in the web tension of process span. The classical PID control result in tension spikes with the change in roll diameter of winder and unwinder rolls. The presence of dancer in R2R system shows that improved web tension control in printing span and the web tension can be enhanced from 3.75 N to 4.75 N. The overshoot of system is less than ±2.5 N and steady state error is within ± 1 N where load cells have a signal noise of ±0.7 N. The integration of load cells and active dancer with self-adapting neural network control provide a solution to the web tension control of multispan roll-to-roll system.

关键词： roll-to-roll(R2R)system multispan printed electronics active dancer load cell artificial neural networks tension control,multi-input-single-output(MISO )

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