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Enhanced Oxidation Resistance of Iron Nanoparticles via Surface Modification in Chemical Vapor Condensation Process

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Journal of Materials Science & Technology 2010年第4期26卷 367-370页

作者： Dong-Won Lee ji-Hun Yu Taesuk Jang Byoung-kee Kim Korea Institute of Materials Science Changwon 641-831 Korea Department of Electronic Materials Sunmoon University Asan 336-708 Korea 不详

In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance in ordinary condition, iron nanoparticles synthesized by a chemical vapor condensation method were directly soaked in hexadecanethiol solution to coat them with a polymer layer. Oxygen content in the polymer-coated iron nanoparticles was significantly lower than that in usual air-passivated particles possessing iron-core/oxide-shell structure. Accordingly, oxidation resistance of the polymer-coated particles at an elevated temperature below 130℃ in air was 10-40 times higher than that of the normally passivated particles.

关键词： Powder technology Nano materials Iron Chemical vapor condensation

Complications of common bile duct stones: A risk factors analysis

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Hepatobiliary & Pancreatic Diseases International 2021年第4期20卷 361-365页

作者： Dong Jun Oh ji Hyung Nam Dong kee Jang Jun Kyu Lee Department of Internal Medicine Dongguk University Ilsan HospitalGoyang 10326Korea

Background: The latest guidelines recommended that common bile duct stones(CBDSs) should be removed, preferably endoscopically, regardless of the presence of symptoms or complications. However, the removal of CBDSs may not be feasible in very old patients or those with co-morbidities. In these cases, it is important to understand the risk factors for the development of CBDSs-related complications to decide whether or not to treat high-risk patients. Herein, we aimed to identify the risk factors for the development of complications after the diagnosis of CBDSs. Methods: The medical records of patients with CBDSs between October 2005 and September 2019 were retrospectively analyzed. All patients with radiologically-diagnosed CBDSs, including those who received treatment and those who did not, were analyzed. Results: A total of 634 patients were included and 95(15.0%) patients had CBDS-related complications during the mean follow-up period of 32.6 months. Forty-four(6.9%) high-risk patients remained asymptomatic and did not receive treatment during the follow-up period. In multivariate analyses, size of CBDSs ≥ 5 mm and no treatment within 30 days were independent risk factors for the development of complications. The spontaneous passage of CBDSs was proved radiologically in 9 out of 81(11.1%) patients within 30 days. Conclusions: It is recommended treating CBDSs within 30 days from the diagnosis, even in high-risk patients, especially if the size is larger than 5 mm.

关键词： Common bile duct stone Risk factors Obstructive jaundice Pancreatitis Cholangitis

Stable Zn Metal Anodes with Limited Zn-Doping in MgF_(2) Interphase for Fast and Uniformly Ionic Flux

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Nano-Micro Letters 2022年第3期14卷 169-183页

作者： ji Young Kim Guicheng Liu Ryanda Enggar Anugrah Ardhi jihun Park Hansung Kim Joong kee Lee Energy Storage Research Center Korea Institute of Science and TechnologyHwarang‑ro 14‑gil 5Seongbuk‑guSeoul 02792Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei‑roSeodaemun‑guSeoul 03722Republic of Korea Department of Physics Dongguk UniversitySeoul 04620Republic of Korea APC Technology 10868 Gangbyeonyeok‑ro‑4‑gilGwangjin‑guSeoul 05116Republic of Korea Department of Energy and Environmental Engineering KIST SchoolKorea University of Science and TechnologyHwarang‑ro 14‑gil 5Seongbuk‑guSeoul 02792Republic of Korea

The practical applications of aqueous Zn metal batteries are currently restricted by the inherent drawbacks of Zn such as the hydrogen evolution reaction,sluggish kinetics,and dendrite *** address these problems,herein,a limitedly Zn-doped MgF_(2)interphase comprising an upper region of pure,porous MgF_(2)and a lower region of gradient Zn-doped MgF_(2)is achieved via radio frequency sputtering *** porous MgF_(2)region is a polar insulator whose high corrosion resistance facilitates the de-solvation of the solvated Zn ions and suppression of hydrogen evolution,resulting in Zn metal electrodes with a low interfacial *** Zn-doped MgF_(2)region facilitates fast transfer kinetics and homogeneous deposition of Zn ions owing to the interfacial polarization between the Zn dopant and MgF_(2)matrix,and the high concentration of the Zn dopant on the surface of the metal substrate as fine ***,a symmetric cell incorporating the proposed Zn metal exhibits low overpotentials of~27.2 and~99.7 mV without Zn dendrites over 250 to 8000 cycles at current densities of 1.0 and 10.0 mA cm−2,*** developed Zn/MnO2 full cell exhibits superior capacity retentions of 97.5%and 84.0%with average Coulombic efficiencies of 99.96%after 1000 and 3000 cycles,respectively.

关键词： Zinc metal battery MgF_(2)layer Limited zinc doping Ion-transfer kinetic Deposition guidance

Reversible Zn/polymer heterogeneous anode

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Carbon Energy 2023年第6期5卷 82-91页

作者： Lingyun Xiong Hao Fu Kai Yang ji Young Kim Ren Ren Joong kee Lee Woochul Yang Guicheng Liu Department of Physics Dongguk UniversitySeoulRepublic of Korea School of Energy Power and Mechanical Engineering North China Electric Power UniversityBeijingChina Energy Storage Research Center Clean Energy InstituteKorea Institute of Science and Technology(KIST)Seongbuk‐guSeoulRepublic of Korea Department of Materials Science and Engineering City University of Hong KongKowloonHong KongChina

Commercialization of Zn-metal anodes with low cost and high theoretical capacity is hindered by the poor reversibility caused by dendrites growth,side reactions,and the slow Zn^(2+)-transport and reaction ***,a reversible heterogeneous electrode of Zn-nanocrystallites/polyvinylphosphonic acrylamide(Zn/PPAm)with fast electrochemical kinetics is designed for the first time:phosphonic acid groups with strong polarity and chelation effect ensure structural reversibility and stability of the threedimensional Zn-storage-host PPAm network and the Zn/PPAm hybrid;hydrophobic carbon chains suppress side reactions such as hydrogen evolution and corrosion;weak electron-donating amide groups constitute Zn^(2+)-transport channels and promote“desolvation”and“solvation”effects of Zn^(2+)by dragging the PPAm network on the Zn-metal surface to compress/stretch during Zn plating/stripping,respectively;and the heterostructure and Zn nanocrystallites suppress dendrite growth and enhance electrochemical reactivity,***,the Zn/PPAm electrode shows cycle reversibility of over 6000 h with a hysteresis voltage as low as 31 mV in symmetrical cells and excellent durability and flexibility in fiber-shaped batteries.

关键词： dendrite-free electrode process kinetics fiber-shaped battery reversible metal/polymer heterostructure Zn-metal anode

An inducible CRISPR-ON system for controllable gene activation in human pluripotent stem cells

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Protein & Cell 2017年第5期8卷 379-393页

作者： jianying Guo Dacheng Ma Rujin Huang jia Ming Min ye Kehkooi kee Zhen Xie jie Na Department of Basic Medical Sciences School of Medicine Center for Stem Cell Biology Tsinghua University Beijing 100084 China MOE Key Laboratory of Bioinformatics and Bioinformatics Division Center for Synthetic and System Biology TNLIST/ Department of Automation Tsinghua University Beijing 100084 China

Human pluripotent stem cells （hPSCs） are an important system to study early human development, model human diseases, and develop cell replacement therapies. However, genetic manipulation of hPSCs is challenging and a method to simultaneously activate multiple genomic sites in a controllable manner is sorely needed. Here, we constructed a *** system to efficiently upregulate endogenous genes in hPSCs. A doxycycline （Dox） inducible dCasg-VP64-p65-Rta （dCas9-VPR） transcription activator and a reverse Tet transactivator （rtTA） expression cassette were knocked into the two alleles of the AAVS1 locus to generate an iVPR hESC line. We showed that the dCas9-VPR level could be precisely and reversibly controlled by the addition and withdrawal of Dox. Upon transfection of multiplexed gRNA plasmid targeting the NANOG pro- moter and Dox induction, we were able to control NANOG gene expression from its endogenous locus. Interestingly, an elevated NANOG level promoted naive pluripotsnt gene expression, enhanced cell survival and clonogenicity, and enabled hESCs to integrate with the inner cell mass （ICM） of mouse blastocysts in vitro. Thus, iVPR cells provide a convenient platform for gene function studies as well as high-throughput screens in hPSCs.

关键词： CRISPR transcription activation humanpluripotent stem cells NANOG pluripotency

Turbulent vortex trains in narrow square arrayed rod bundles of a dual-cooled nuclear reactor

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Science China(Technological Sciences) 2013年第9期56卷 2143-2149页

作者： KIM Taehwan KIM Kyung Min BAE ji-yeul SHIN Chang Hwan IN Wang-kee CHO Hyung Hee School of Mechanical Engineering Yonsei University Korea Atomic Energy Research Institute

The dual-cooled nuclear reactor is currently considered for improving the designs of current/future nuclear reactors. Investigation of the thermal-hydraulic characteristics of the nuclear reactor via experiments is essential for commercializing the dual-cooled nuclear reactor. In this paper, the turbulent flow in square arrayed six-rod bundles in the form of magnified copies of the dual-cooled and current OPR-1000 nuclear reactor is experimentally investigated by means of hot-wire anemometry and smoke-wire generation methods. Vortex trains which do not exist in an ordinary reactor subchannel are presented in the subchannel of the dual-cooled reactor. The vortices are induced by a span-wise velocity gradient. This flow pulsation phenomenon increases the inter-channel mixing of the subchannel. To understand the periodic feature of the pulsation, axial/cross velocities are measured and the periodic characteristic frequencies are obtained by a Fast Fourier Transform (FFT) analysis. The peak frequency that represents the quasi-periodic pulsation of the flow is increased with an increase in the axial velocity while the wavelength of the pulsation remains constant within a tested range of the Reynolds number (9000 51000). The vortex trains are highly synchronized with each other, as confirmed by means of visualization.

关键词： dual-cooled nuclear reactor vortex train flow pulsation turbulent mixing rod bundles

Foliations associated to harmonic maps on some complex two ball quotients

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Science China Mathematics 2017年第6期60卷 1137-1148页

作者： yeUNG Sai-kee Department of Mathematics Purdue University West Lafayette IN 47907 USA

This article is an attempt to understand harmonic and holomorphic maps between two bounded symmetric domains in special situations. We study foliations associated to a lattice-equivariant harmonic map of small rank from a complex ball to another. The result is related to rigidity of some complex two ball *** open questions are raised as well.

关键词： harmonic maps foliations rigidity

Efficient Flexible M-Tree Bulk Loading Using FastMap and Space-Filling Curves

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Computers, Materials & Continua 2021年第2期66卷 1251-1267页

作者： Woong-kee Loh Department of Software Gachon UniversitySeongnam13120South Korea

Many database applications currently deal with objects in a metric *** of such objects include unstructured multimedia objects and points of interest(POIs)in a road *** M-tree is a dynamic index structure that facilitates an efficient search for objects in a metric *** have been conducted on the bulk loading of large datasets in an ***,because previous algorithms involve excessive distance computations and disk accesses,they perform poorly in terms of their index construction and search *** study proposes two efficient M-tree bulk loading *** algorithms minimize the number of distance computations and disk accesses using FastMap and a space-filling curve,thereby significantly improving the index construction and search *** second algorithm is an extension of the first,and it incorporates a partitioning clustering technique and flexible node architecture to further improve the search *** the use of various synthetic and real-world datasets,the experimental results demonstrated that our algorithms improved the index construction performance by up to three orders of magnitude and the search performance by up to 20.3 times over the previous algorithm.

关键词： M-tree metric space bulk loading FastMap space-filling curve

Clinical and ABCB11 profiles in Korean infants with progressive familial intrahepatic cholestasis

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World Journal of Gastroenterology 2016年第20期22卷 4901-4907页

作者： ji Sook Park Jae Sung Ko Jeong kee Seo jin Soo Moon Sung Sup Park Department of Pediatrics Seoul National University College of Medicine Department of Pediatrics Gyeongsang National University School of Medicine Department of Laboratory Medicine Seoul National University College of Medicine

AIM: To investigate clinical profiles and mutations of ABCB11 in Koreans with progressive familial intrahepatic cholestasis 2 and review the differences between Koreans and ***: Of 47 patients with neonatal cholestasis, five infants had chronic intrahepatic cholestasis with normal γ-glutamyl transpeptidase. Direct sequencing analyses of ABCB11, including exons and introns, were performed from peripheral ***: Living donor-liver transplantation was performed in four patients because of rapidly progressive hepatic failure and hepatocellular carcinoma. Three missense mutations were found in two patients: compound heterozygous 677C>T(S226L)/3007G>A(G1003R) and heterozygous 2296G>A(G766R). The mutations were located near and in the transmembranous space. CONCLUSION: Alterations in the transmembrane of the bile salt export pump in the Korean infants were different from those previously reported in Chinese, Japanease, Taiwan Residents, and European patients.

关键词： Hepatocellular carcinoma Progressive familial intrahepatic cholestasis ABCB11 Bile salt export pump