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Tuning the base properties of Mg–Al hydrotalcite catalysts using their memory effect

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Journal of Energy Chemistry 2020年第7期29卷 229-236,I0008页

作者： Dahye kwon ji Yeon Kang Suna An Inchan Yang ji Chul Jung Department of Chemical Engineering Myongji UniversityYongin 17058Republic of Korea

Herein,the relationship between the structure and base properties of Mg–Al hydrotalcite catalysts was comprehensively investigated in relation to heat treatment and rehydration processes,which are well known as memory effects of *** structure of Mg–Al hydrotalcites changed from layered double hydroxide(LDH)to mixed metal oxide and subsequently to a spinel structure during heat treatment,and it was returned from mixed metal oxide to a LDH structure by *** on various characterizations,we successfully proposed a detailed mechanism of memory *** also confirmed that the Mg–Al hydrotalcites had weak or strong base sites and that their base properties could be systematically tuned by heat treatment and *** prepared Mg–Al hydrotalcites were applied to a model reaction,isomerization of glucose to fructose,as base *** the catalysts tested,the rehydrated Mg–Al hydrotalcite efficiently produced fructose due to its appropriate base and structure *** finally concluded that the base sites of Mg–Al hydrotalcites can be designed as desired by heat treatment and ***,through systematic design of the base sites of Mg–Al hydrotalcites,these can be promising catalysts for various heterogeneous reactions over base catalysts,giving excellent catalytic performances.

关键词： Mg–Al hydrotalcite Structure Base properties Heat treatment Rehydration

Curvature range measurements of the arcuate fasciculus using diffusion tensor tractography

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Neural Regeneration Research 2013年第3期8卷 244-250页

作者： Dong Hoon Lee Cheol Pyo Hong Yong Hyun kwon Yoon Tae Hwang Joong Hwi Kim ji won Park Department of Radiological Science College of Health ScienceYonsei University Department of Physical Therapy Yeungnam College of Science & Technology Department of Physical Therapy Gangneung Yeongdong College Department of Physical Therapy College of Medical ScienceCatholic University of DaeguGyeongsan-si

Because Broca＇s area and Wernicke＇s area in the brain are connected by the arcuate fasciculus, understanding the anatomical location and morphometry of the arcuate fasciculus can help in the treatment of patients with aphasia. We measured the horizontal and vertical curvature ranges of the arcuate fasciculus in both hemispheres in 12 healthy subjects using diffusion tensor tractography. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus horizontal part were 121.13 ± 5.89 and 25.99 ± 3.01 degrees, respectively, and in the left hemisphere, the values were 121.83 ± 5.33 and 27.40 ± 2.96 degrees, respectively. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus vertical part were 43.97 ± 7.98 and 30.15 ± 3.82 degrees, respectively, and in the left hemisphere, the values were 39.39 ± 4.42 and 24.08 ± 4.34 degrees, respectively. We believe that the measured curvature ranges are important data for localization and quantitative assessment of specific neuronal pathways in patients presenting with arcuate fasciculus abnormalities.

关键词： neural regeneration neuroimaging clinical practice diffusion tensor tractography diffusion tensor imaging arcuate fasciculus direct curvature range indirect curvature range anatomical location quantitative information aphasia Broca’s area Wernicke’s area arched fiber grant-supported paper photographs-containing paper neuroregeneration

Electrochemical partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni via coupled oxidation of an interfacing NiAl intermetallic compound for robust hydrogen evolution

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Journal of Energy Chemistry 2023年第7期82卷 560-571,I0012页

作者： Young Hwa Yun Kwangsoo Kim Changsoo Lee Byeong-Seon An ji Hee kwon Sechan Lee MinJoong Kim Jongsu Seo Jong Hyeok Park Byung-Hyun Kim Hyun-Seok Cho Hydrogen Research Department Korea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Computational Science&Engineering Laboratory Korea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Analysis Center for Energy Research Korea Institute of Energy Research152 Gajeong-roYuseong-guDaejeon 34129Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea

Ni-based porous electrocatalysts have been widely used in the hydrogen evolution reaction(HER)in alkaline water electrolysis,and the catalysts are produced by selective leaching of Al from Ni-Al *** is well known that chemical leaching of Ni-Al intermetallic compound(IMC)generates a high surface area in Ni(OH)_(2).However,the Ni(OH)_(2) produced by leaching the Ni-Al intermetallic compound retards the hydrogen evolution reaction,which is attributed to its weak hydrogen adsorption *** this study,we controlled the chemical state of Ni using plasma vapor deposition(PVD)followed by heat treatment,selective Al leaching,and electrochemical reduction.X-ray diffraction(XRD),scanning microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive X-ray spectroscopy(EDS)were used to confirm the phase evolution of the electrocatalysts during *** reveal that the heat-treated Ni-Al alloy with a thick Ni2Al3surface layer underwent selective Al leaching and produced biphasic interfaces comprising Ni(OH)_(2) and NiAl IMCs at the edges of the grains in the outermost surface *** oxidation of the interfacing NiAl IMCs facilitated the partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni in the grains during electrochemical reduction,as confirmed by X-ray photoelectron spectroscopy(XPS).An electrocatalyst containing partially reduced Ni(OH)_(2)/Ni exhibited an overpotential of 54 mV at 10 mA/cm^(2) in a half-cell measurement,and a cell voltage of 1.675 V at 0.4 A/cm2for single-cell operation.A combined experimental and theoretical study(density functional theory calculations)revealed that the superior HER activity was attributed to the presence of partially reduced metallic Ni with various defects and residual Al,which facilitated water adsorption,dissociation,and finally hydrogen evolution.

关键词： Raney nickel HERChemical leaching Intrinsic activity Partial reduction

Amine axial ligand-coordinated cobalt phthalocyanine-based catalyst for flow-type membraneless hydrogen peroxide fuel cell or enzymatic biofuel cell

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Journal of Energy Chemistry 2021年第7期30卷 463-471页

作者： Heeyeon An Hyewon Jeon Jungyeon ji Yongchai kwon Yongjin Chung Department of Chemical and Biological Engineering Korea National University of Transportation50 Daehak-roChungjuChungbuk 27469Republic of Korea Graduate School of Energy and Environment Seoul National University of Science and Technology 232 Gongneung-roNowon-guSeoul 01811Republic of Korea Department of Chemical and Biomolecular Engineering Seoul National University of Science and Technology232 Gongneung-roNowon-guSeoul 01811Republic of Korea Department of ITÁEnergy Convergence(BK21 FOUR) Korea National University of Transportation50 Daehak-roChungjuChungbuk 27469Republic of Korea

In this study,an amine-coordinated cobalt phthalocyanine(CoPc)-based anodic catalyst was fabricated by a facile process,to enhance the performance of hydrogen peroxide fuel cells(HPFCs) and enzymatic biofuel cells(EBCs).For this purpose,polyethyleneimine(PEI) was added onto the reduced graphene oxide and CoPc composite(RGO/CoPc) to create abundant NH2 axial ligand groups,for anchoring the Co core within the *** to the PEI addition,the onset potential of the hydrogen peroxide oxidation reaction was shifted by 0.13 V in the negative direction(0.02 V) and the current density was improved by 1.92 times(1.297 mA cm^(-2)),compared to those for RGO/CoPc(0.15 V and 0.676 mA cm^(-2),respectively),due to the formation of donor-acceptor dyads and the prevention of CoPc from leaching *** biocatalyst using glucose oxidase(GOx)([RGO/CoPc]/PEI/GOx) showed a better onset potential and catalytic activity(0.15 V and 318.7 μA cm^(-2)) than comparable structures,as well as significantly improved operational durability and long-term *** is also attributed to PEI,which created a favorable microenvironment for the *** maximum power densities(MPDs) and open-circuit voltages(OCVs) obtained for HPFCs and EBCs using the suggested catalyst were 105.2±1.3 μW cm^(-2)(0.317±0.003 V) and 25.4±0.9 μW cm^(-2)(0.283±0.007 V),*** shows that the amine axial ligand effectively improves the performance of the actual driving HPFCs and EBCs.

关键词： Hydrogen peroxide fuel cell Enzymatic biofuel cell Amine axial ligand Hydrogen peroxide oxidation reaction Membraneless

Flexible micro-LED display and its application in Gbps multi-channel visible light communication

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npj Flexible Electronics 2022年第1期6卷 973-979页

作者： Luhing Hu Jaeyong Choi Sumin Hwangbo Do-Hoon kwon Bongkyun Jang Seunghyeon ji Jae-Hyun Kim Sang-Kook Han Jong-Hyun Ahn School of Electrical and Electronic Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of Nanomechanics Nano-Convergence Mechanical Systems Research DivisionKorea Institute of Machinery&Materials(KIMM)156 Gajeongbuk-roYuseong-guDaejeon 34103Republic of Korea

A flexible full-color micro-LED display with high mechanical robustness was fabricated by printing quantum dots(QDs)on a blue micro-LED array using standard *** red and green colors yielded from QDs exhibit a better color gamut than conventional color *** light conversion efficiency was enhanced by adding TiO2 nanoparticles to the QD-photoresist *** full-color micro-LED display was successfully mounted on various unusual substrates such as curved glass,fabrics,and human skin,enabling diverse optoelectronic *** addition,wireless multi-channel visible light communication(VLC)based on the wavelength-division-multiplexing orthogonal-frequency-division-multiplexing(WDM-OFDM)technique was demonstrated using a QD-based color micro-LED panel.A high data transmission rate of 1.9 Gbps was successfully obtained owing to the high electrical-optical modulation bandwidth of the QD-based micro-LED panel.

关键词： communication Gbps visible

On the factors of Bitcoin’s value at risk

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Financial Innovation 2021年第1期7卷 1855-1885页

作者： ji Ho kwon College of Business Gachon University1342 Seongnam‑daeroSujeong‑guSeongnam‑siGyeonggi‑doRepublic of Korea

This study investigates the factors of Bitcoin’s tail risk,quantified by Value at Risk(VaR).Extending the conditional autoregressive VaR model proposed by Engle and Manganelli(2004),I examine 30 potential drivers of Bitcoin’s 5%and 1%*** the 5%VaR,quantity variables,such as Bitcoin trading volume and monetary policy rate,were positively significant,but these effects were attenuated when new samples were *** 5%VaR responds positively to the Internet search index and negatively to the fluctuation of returns on commodity variables and the Chinese stock market *** the 1%VaR,variables related to the macroeconomy play a key *** consumer sentiment index exerts a strong positive effect on the 1%VaR.I also find that the 1%VaR has positive relationships with the US economic policy uncertainty index and the fluctuation of returns on the corporate bond index.

关键词： Bitcoin Value at risk CAViaR

Performance and genetic diversity of 23 provenances of northern red oak(Quercus rubra L.)after 25 years of growth in South Korea

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Journal of Forestry Research 2021年第5期32卷 2181-2188页

作者： Ki-won Kim Kyoung-Mi Lee Soon-Ho kwon ji-Min Park Yang-Gil Kim Hye-In Kang Da-Bin Yum Kyu-Suk Kang Department of Agriculture Forestry and BioresourcesSeoul National UniversitySeoul 08826Republic of Korea Department of Forest Bioresources National Institute of Forest ScienceSuwon 16631Republic of Korea Department of Plant Resource Research Korea National ArboretumPocheon 11186Republic of Korea Research Institute of Agriculture and Life Sciences CALS_SNUSeoul 08826Republic of Korea

Growth traits and genetic diversity of 23 provenances of Quercus rubra introduced from North America were analyzed in a provenance trial established with a randomized block design in Hwaseong,Gyeonggi,South Korea in *** variables and survival at age 25 were compared with results from early ***,DBH,volume and stem straightness of *** was better than those of the domestic oak(Quercus accutissima).Growth of the Dunham Island provenance from New York was the best among the 23 provenances that of the Eagle River provenance from Wisconsin was *** rate at age25 was on average 52%.The longitude of seed origin and growth of provenance were consistently significantly negatively correlated at all *** of coastal provenances was superior to that of the inland provenances,which were separated by the Appalachian *** diversity and genetic distance among the provenances were evaluated using micro satellite *** allelic frequencies showed high polymorphism in 10 microsatellite loci,and 292 alleles were *** 10 loci,two were commonly found in the 23 *** mean allelic diversity and heterozygosity observed among the provenances were similar to those from the native populations of *** in North ***’s genetic distance among the 23 was estimated and showed that a clear trend between geographic and genetic distances,indicating that some provenances have high genetic diversity with superior growth performance.

关键词： Introduction breeding Provenance test Adaptation Microsatellite marker Genetic distance

Multivalent network modifier upregulates bioactivity of multispecies biofilm-resistant polyalkenoate cement

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Bioactive Materials 2022年第8期7卷 219-233页

作者： ji-Yeong Kim Woojin Choi Utkarsh Mangal ji-Young Seo Tae-Yun Kang Joohee Lee Taeho Kim Jung-Yul Cha Kee-Joon Lee Kwang-Mahn Kim jin-Man Kim Dohyun Kim Jae-Sung kwon jinkee Hong Sung-Hwan Choi Department of Orthodontics Institute of Craniofacial DeformityYonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea BK21 FOUR Project Yonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Department of Chemical and Biomolecular Engineering Yonsei University50 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Department and Research Institute of Dental Biomaterials and Bioengineering Yonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea Johns Hopkins University 3400 N.Charles St.Mason HallBaltimoreMD 21218USA Department of Oral Microbiology and Immunology School of Dentistry and Dental Research InstituteSeoul National UniversitySeoul 08826Republic of Korea Department of Conservative Dentistry Oral Science Research CenterYonsei University College of Dentistry50-1 Yonsei-roSeodaemun-guSeoul 03722Republic of Korea

Polyalkenoate cement(PAC)is a promising material for regenerative hard tissue *** ionically rich glass component of PAC encourages bioactive interaction *** release of essential ***,PAC bioactivity is restricted owing to(i)structurally inherent cationic network formers and(ii)surface bacterial biofilm *** two factors cause a deficiency in ion release,further complicated by secondary infections and premature therapeutic ***,a multivalent zwitterionic network modifier(mZM)is presented for upregulation of ionic exchange and bioactivity *** introducing a non-zero charged mZM into PACs,an increase in the proportion of non-bridging oxygen *** network modification promotes ion channel formation,causing a multiple-fold increase in ion release and surface deposition of hydroxy-carbonate apatite(ca.74%).Experiments ex vivo and animal models also demonstrate the efficient remineralization ability of the ***,divalent cationic interaction results in bacterial biofilm reduction(ca.68%)while also influencing a shift in the biofilm species composition,which favors commensal ***,PAC modification with mZM offers a promising solution for upregulation of bioactivity,even aiding in customization by targeting site-specific regenerative therapy in future applications.

关键词： Multivalent network modifier Bioactive materials Glass polyalkenoate cement Ion release Remineralization Multispecies biofilm resistance

Anti-cancer effect of ethylacetate fraction from Orostachys japonicus on HT-29 human colon cancer cells by induction of apoptosis through caspase-dependent signaling pathway

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Asian Pacific Journal of Tropical Medicine 2018年第5期11卷 330-335页

作者： Deok-Seon Ryu Hyun-ji Lee ji-Hye kwon Dong-Seok Lee Department of Biomedical Laboratory Science Soonchunhyang University Department of Smart Foods and Drugs Graduate School of Inje University

Objective: To investigate the anti-colon cancer effects of ethylacetate fraction from Orostachys japonicus(0. japonicus) on HT-29 cancer cells. Methods: The viability of HT-29 cells was assayed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium(MTS) method. Apoptosis induction and cell cycle inhibition were confirmed by fluorescein isothiocyanate and propidium iodide staining using flow *** changes in the nucleus were observed, using a fluorescence microscope with4',6-diamidino-2-phenylindole(DAPI) nuclear staining. The expression levels of the upstream and downstream proteins involved in the anti-cancer mechanism were confirmed by Western blotting. Results: After treating HT-29 cells with different concentrations of ethylacetate fraction from O. japonicus, the viability of cells decreased in a concentration-dependent manner,while apoptosis induction and apoptotic body formation increased. Cell cycle analysis showed that the arrest occurred at the sub-G_1 and S phase. Among the upstream and downstream proteins involved in anti-cancer activity, the level of B cell lymphoma-2 decreased, and the bcl-2-associated x protein increased. The level of pro-caspase-3, pro-caspase-8, and pro-caspase-9 decreased, while the level of cleaved-caspase-3, cleaved-caspase-8, and cleaved-caspase-9 increased. Moreover, the phosphorylation, that is, activation of extracellular signal regulated kinase 1/2, Jun-N-terminal kinase, and p38 increased. Conclusions: Combining the above results, it is thought that the survival of HT-29 cells is suppressed by ethylacetate fraction from0. japonicus through mitochondrial regulation-induced caspase cascade activation, induction of apoptosis and cell cycle arrest.

关键词： Orostachys japonicus HT-29 human colon cancer cells Anti-cancer activity Apoptosis Caspase cascade