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Inhibition of BET selectively eliminates undifferentiated pluripotent stem cells

Science Bulletin 2018年第8期63卷 477-487页

作者： Jung hyun Im Seon In Hwang Jong-Wan kim soon-Jung Park Kyu-ree Kang Jueng Soo You Kee pyo kim Sung-Hwan Moon Hyuk-Jin Cha hyung-Min Chung Hans R. Scholer Jung Keun hyun DongWook Han Department of Stem Cell Biology School of Medicine Konkuk University Seoul 05029 Republic of Korea Department of Nanobiomedical Science Dankook University Graduate School Cheonan 330714 Republic of Korea Department of Biochemistry School of Medicine Konkuk University Seoul 05029 Republic of Korea Department of Cell and Developmental Biology Max Planck Institute for Molecular Biomedicine 48149 Munster Germany Department of Life Sciences College of Natural Sciences Sogang University Seoul 04107 Republic of Korea KU Open-lnnovation Center. Institute of Biomedical Science & Technology Konkuk University Seoul 05029 Republic of Korea Department of Advanced Translational Medicine School of Medicine Konkuk University Seoul 05029 Republic of Korea

Embryonic stem cells （ESCs） maintain their cellular identity through the systematic regulation of master transcription factors and chromatin remodeling complexes. Recent work has shown that the unusually large-scale enhancers-namely super-enhancers （SEs）, on which BRD4, a member of the bromodomain and extraterminal domain （BET） family is highly enriched-could regulate pluripotency-related transcrip- tion factors. Moreover, inhibition of BRD4 binding on SEs has been shown to induce the differentiation of ESCs. However, the underlying mechanism of BRD4 inhibition-mediated stern cell differentiation remains elusive. Here we show that both mouse and human ESCs lose their capacity for self-renewal upon treat- ment with JQ1, a selective inhibitor of BET family including BRD4, with rapid suppression of pluripotency-associated genes. Notably, a high concentration of JQI could selectively eliminate ESCs via apoptosis, without affecting the functionality of differentiated somatic cells from ESCs, suggesting that inhibition of BET may have a beneficial effect on the development of pluripotent stem cell-based cell therapy.

关键词： Bromodomain and extraterminal domain (BET) JQ1 Pluripotent stem cells

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Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief

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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

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Yolk-shell-structured （***.s）9S8 solid-solution powders：Synthesis and application as anode materials for Na-ionbatteries

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Nano Research 2017年第9期10卷 3178-3188页

作者： Jung hyun kim Yun Chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea

Multicomponent metal sulfide materials with a yolk–shell structure and a single phase were studied for the first time as anode materials for sodium-ion batteries. Yolk–shell-structured Fe–Ni–O powders with a molar ratio of iron and nickel components of 1/1 were prepared via one-pot spray pyrolysis. The prepared Fe–Ni–O powders were transformed into yolk–shell-structured (Fe0.5Ni0.5)9S8 solid-solution powders via a sulfidation process. The initial discharge and charge capacities of the (Fe0.5Ni0.5)9S8 powders at a current density of 1 A·g−1 were 601 and 504 mA·h·g−1, respectively. The discharge capacities of the (Fe0.5Ni0.5)9S8 powders for the 2nd and 100th cycle were 530 and 527 mA·h·g−1, respectively, and their corresponding capacity retention measured from the 2nd cycle was 99%. The (Fe0.5Ni0.5)9S8 powders had high initial discharge and charge capacities at a low current density of 0.1 A·g−1, and the reversible discharge capacity decreased slightly from 568 to 465 mA·h·g−1 as the current density increased from 0.1 to 5.0 A·g−1. The synergetic effect of the novel yolk–shell structure and the multicomponent sulfide composition of the (Fe0.5Ni0.5)9S8 powders resulted in excellent sodium-ion storage performance.

关键词： metal sulfide multicomponent sulfide yolk–shell sodium-ion batteries spray pyrolysis

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Effects of Polymeric Stabilizers on the Synthesis of Gold Nanoparticles

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Journal of Materials Science & Technology 2014年第2期30卷 107-111页

作者： Eun Jung kim Jeong hyun Yeum Jin hyun Choi Department of Advanced Organic Materials Science and Engineering Kyungpook National University Department of Bio-fibers and materials Science Kyungpook National University

Gold nanoparticles （AuNPs） stabilized with sodium alginate （SA）, glycol chitosan （GC）, polyvinyl alcohol （PVA）, and polyethyleneimine （PEI） were synthesized in aqueous solutions at room temperature. Different sizes and size distributions of AuNPs were obtained according to the polymeric stabilizers. The mean particle diameters of AuNPs synthesized with GC and PVA as stabilizers were about 5.1 and 5.3 nm, respectively, while those of AuNPs stabilized with SA and PEI were 8.4 and 10.8 nm, respectively. When SA was used, relatively large particles aggregated to form large clusters. In the case of GC, a number of small particles built up large clusters. When PVA was used, the size and the number of nanoperticles were estimated small with a low weight content of Au. For this reason, the PVA-stabilized AuNPs formed clusters with a small hydrodynamic size. The AuNPs synthesized in the aqueous solution of PEI without a reducing agent, sodium borohydride, were uniform in size and formed the smallest nanoclusters （67.4 nm）. In this case, the highest Au content was obtained. Sufficiently grown nanoparticles with a high Au content and a limited hydrodynamic size are considered to be suitable for a variety of applications.

关键词： Gold nanoparticles Sodium alginate Glycol chitosan Polyvinyl alcohol Polyethyleneimine

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Laboratory investigation of the anisotropic confinement-dependent brittle-ductile transition of a Utah coal

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International Journal of Mining Science and Technology 2021年第1期31卷 51-57页

作者： Bo-hyun kim Mark K.Larson Mine Safety Branch CDC/NIOSH/SMRDSpokaneWA 99207USA

This paper was developed as part of an effort by the National Institute for Occupational Safety and Health(NIOSH)to identify risk factors associated with bumps in the prevention of fatalities and accidents in highly stressed,bump-prone ground *** of failure mechanism with increasing confinement,from extensional-to shear-dominated failure,are widely observed in the rupture of intact specimens at the laboratory scale and in rock *** the previous analysis conducted in 2018,both unconfined and triaxial compressive tests were conducted to investigate the strength characteristics of some specimens of a Utah coal,including the spalling limits,the ratio of apparent unconfined compressive strength(AUCS)to unconfined compressive strength(UCS),the damage characteristics,and the postyield *** mechanical characteristics were found to be strongly anisotropic as a function of the orientation of the cleats relative to the loading ***,the transition from extensional to shear failure at the given confinements was not clearly *** this study,a total of 20 specimens were additionally prepared from the same coal sample used in the previous study and then tested under both unconfined and triaxial compressive *** different confining stresses are used as analogs for different width-to-height(W/H)ratios of pillar *** the W/H ratios of the specimens were not directly considered during testing,the equivalent W/H ratios of a pillar as a function of the confining stresses were estimated using an existing empirical *** to this relationship,theW/H atwhich in-situ pillar behavior would be expected to transition from brittle to ductile is identified.

关键词： Bump-prone ground conditions A Utah coal Anisotropic Equivalent W/H ratios of a pillar

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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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Anti-obesity Effects of Ginsenosides in High-Fat Diet-Fed Rats

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Chinese Journal of Integrative Medicine 2019年第12期25卷 895-901页

作者： hyun-Jung Park Ji hyun kim Insop Shim Department of Physiology College of MedicineKyung Hee UniversitySeoul(130-701)Republic of Korea Department of Food Science&Biotechnology College of Science and EngineeringSuwon-si(16227)Republic of Korea

Objective: To examine the anti-obesity effects of ginsenosides in Korea Red Ginseng(KRG, Panax ginseng) in rats fed with a high-fat diet(HFD). Methods: Twenty-five 4-week-old obesity rats after receiving an HFD for 5 weeks;subsequently, they were additionally treated with ginsenosides Rb1, Rd, Rg1, or Re(10 mg/kg, intraperitoneal injection) for a further 3 weeks(n=5 in each group). The control rats were fed a normal diet. The food consumption, body weight, locomotor activity, serum lipids, adipose tissues, nitric oxide(NO) expression, leptin, neuropeptide Y(NPY), cholecystokinin(CCK) in the brains were measured. Results: In the HFD-fed rats, body weight, body fat mass, serum levels of leptin and NO were significantly higher than in the control rats(P<0.05 or P<0.01). However, the treatment of Rd, Re, and Rb1 markedly decreased body fat mass and body weight(P<0.05). The serum level of leptin and NO in ginsenoside-treated rats were markedly lower than the control group(P<0.01). The expression of NPY and CCK in the hypothalamic nuclei showed insignificant difference among groups. However, the expression of NPY immunoreactive neurons in the hypothalamus was significantly reduced in the Rb1-treated group(P<0.05). Conclusion: PD-type ginsenoside Rb1 from the crude saponins of KRG may be a useful compound for the treatment of obesity and related disorders through the modulation of peripheral and central appetite-regulating signals.

关键词： Panax ginseng ginsenosides hypothalamus obesity

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Microstructure and Mechanical Properties of Hyper-eutectic Al-Si Alloys Fabricated by Spray Casting

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Journal of Materials Science & Technology 2008年第1期24卷 48-50页

作者： Min Ryou Chul-hyun kim Myung-Ho kim School of Materials Science and Engineering Inha University 253 Yonghyun-DongNam-GuIncheon 402-751Korea Dong Yang Piston Co. LTD 1050Singil-DongDonwon-GuAnsanKyungki-DoKorea

Microstructure and mechanical properties of hyper-eutectic Al-Si alloy fabricated by spray casting were in- vestigated and then these results were compared with those by squeeze *** spray-cast specimen was found to have finer Si particles （～5μm） compared to the squeeze-cast specimen （10-25μm）.The tensile strength and elongation of the spray-cast specimen are also higher than those of the squeeze cast *** was considered that the increased mechanical properties of the spray-cast specimen were mainly due to finer size of the Si particles distributed in Al matrix.

关键词： Hyper-eutectic Al-Si alloy Squeeze casting Spray casting

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Direct synthesis of highly conductive poly（3,4- ethylenedioxythiophene）：poly（4-styrenesulfonate）（PEDOT：PSS）/graphene composites and their applications in energy harvesting systems

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Nano Research 2014年第5期7卷 717-730页

作者： Dohyuk Yoo Jeonghun kim Jung hyun kim Department of Chemical and Biomolecular Engineering Yonsei University 50 Yonsei-ro Seodaemun-gu Seou1120-749 Republic of Korea Electronic Materials Division R&D Center Dongjin Semichem Co. Ltd. 625-3 Yodang-Ri Yanggam-Myeon Hwaseong-Gun Gyeonggi-Do Republic of Korea

We report for the first time highly conductive poly（3,4-ethylenedioxythiophene）： poly（4-styrenesulfonate）（PEDOT：PSS）/graphene composites fabricated by in situ polymerization and their applications in a thermoelectric device and a platinum （Pt）-free dye-sensitized solar cell （DSSC） as energy harvesting systems. Graphene was dispersed in a solution of poly（4-styrenesulfonate）（PSS） and polymerization was directly carried out by addition of 3,4-ethylenedioxythiophene （EDOT） monomer to the dispersion. The content of the graphene was varied and optimized to give the highest electrical conductivity. The composite solution was ready to use without any reduction process because reduced graphene oxide was used. The fabricated film had a conductivity of 637 ***-1, corresponding to an enhancement of 41%, after the introduction of 3 wt.% graphene without any further complicated reduction processes of graphene being required. The highly conductive composite films were employed in an organic thermoelectric device, and the device showed a power factor of 45.7 μW·m^-1K^-2 which is 93% higher than a device based on pristine PEDOT：PSS. In addition, the highly conductive composite films were used in Pt-free DSSCs, showing an energy conversion efficiency of 5.4%, which is 21% higher than that of a DSSC based on PEDOT：PSS.

关键词： direct synthesis conductive polymer graphene composite thermoelectric material dye-sensitized solar cell

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Boosting overall water splitting by incorporating sulfur into NiFe(oxy)hydroxide

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Journal of Energy Chemistry 2022年第1期31卷 364-371,I0010页

作者： Chiho kim Seong hyun kim Seunghun Lee Ilyeong Kwon Seong hyun kim Shinho kim Changgyu Seok Yoo Sei Park Yangdo kim Department of Materials Science and Engineering Pusan National UniversityBusan 46241Republic of Korea BK21 Four Innovative Graduate Education Program for Global High-tech Materials&PartsPusan National UniversityBusan 46241Republic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH).Pohang 37673Republic of Korea

Developing highly active and cost-effective electrocatalysts for enhancing the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a significant challenge for overall water ***-incorporated nickel iron(oxy)hydroxide(S-NiFeOOH)nanosheets were directly grown on commercial nickel foam using a galvanic corrosion method and a hydrothermal *** incorporation of sulfur into NiFeOOH enhanced the catalytic activity for the HER and OER in 1 M KOH *** enhanced catalytic activity is attributed to the change in the local structure and chemical states due to the incorporation of *** performance for overall water splitting was achieved with an alkaline water *** was realized by employing S-NiFeOOH as a bifunctional electrocatalyst,thereby outperforming a water electrolyzer that requires the usage of precious metal electrocatalysts(i.e.,Pt/C as the HER electrocatalyst and IrO_(2) as the OER electrocatalyst).Moreover,when driven by a commercial silicon solar cell,an alkaline water electrolyzer that uses S-NiFeOOH as a bifunctional electrocatalyst generated hydrogen under natural *** study shows that S-NiFeOOH is a promising candidate for a large-scale industrial implementation of hydrogen production for overall water splitting because of its low cost,high activity,and *** addition,the solar-driven water electrolyzer using S-NiFeOOH as a bifunctional electrocatalyst affords the opportunity for developing effective and feasible solar power systems in the future.

关键词： Overall water splitting Hydrogen production Sulfur incorporated NiFe(oxy)hydroxide Electrocatalysts Solar-driven water splitting

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