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Improvement of oxidation resistance in graphite for MgO-C refractory through surface modification

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Transactions of Nonferrous Metals Society of China 2014年第S1期24卷 119-124页

作者： Geun-Ho CHO Eun-Hee KIM Jing LI Je-Hyun LEE yeon-gil jung Yun-Ki BYEUN Chang-Yong JO School of Materials Engineering Changwon National University Technical Research Laboratories Pohang Research Laboratory Steelmaking Research Group POSCOPhohang Gyeongbuk 790-300 Korea High Temperature Materials Research Group Korea Institute of Materials Science Changwon Gyeongnam 641-831 Korea

Graphite, used as a carbon source in a conventional magnesia-carbon(MgO-C) refractory, was modified with an acid reagent, resulting in a negative charge on the surface of graphite, to enhance the coating efficiency of aluminum(Al) phase, which was compared to the pristine graphite through its dispersibity and oxidation behavior. The graphite particles with and without surface modification were added, respecticely, in an Al(NO3)3 suspension used as a coating reagent, and then filtered at room temperature. The modified graphite shows better disperbility than the pristine graphite, indicating that the coating efficiency of Al precursor is enhanced in the modified graphite. With respect to oxidation behavior, the modified graphite without the coating layer is totally reacted with oxygen at heat treatment of 900 °C in air. However, the Al-coated graphite starts to react with oxygen at heat treatment of 900 °C and fully reacted with oxygen at heat treatment of 1000 °C, showing the gray and white colors, respectively. It is verified that the Al layer is individually and uniformly formed on the surface of graphite and the oxidation resistance of graphite is enhanced owing to the increased coating efficiency of Al precursor.

关键词： refractory graphite surface modification aluminum coating

Structural basis of DNA binding by the NAC transcription factor ORE1,a master regulator of plant senescence

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Plant Communications 2023年第3期4卷 139-150页

作者： Inseop Chun Hyo jung Kim Sunghyun Hong yeon-gil Kim Min-Sung Kim Department of Life Sciences Pohang University of Science and Technology(POSTECH)PohangGyeongbukRepublic of Korea Center for Plant Aging Research Institute for Basic ScienceDaeguRepublic of Korea Center for Genome Engineering Institute for Basic ScienceDaejeonRepublic of Korea Pohang Accelerator Laboratory Pohang University of Science and TechnologyPohangRepublic of Korea

Plants use sophisticated mechanisms of gene expression to control senescence in response to environmental stress or ***1(Arabidopsis thaliana NAC092)is a master regulator of senescence that belongs to the plant-specific NAC transcription factor protein ***1 has been reported to bind to multiple DNA targets to orchestrate leaf senescence,yet the mechanistic basis for recognition of the cognate gene sequence remains ***,we report the crystal structure of the ORE1-NAC domain alone and its DNA-binding *** structure of DNA-bound ORE1-NAC revealed the molecular basis for nucleobase recognition and phosphate backbone *** showthat local versatility in the DNA-binding site,in combination with domain flexibility of the ORE-NAC homodimer,is crucial for the maintenance of binding to intrinsically flexible *** results provide a platformfor understanding other plant-specific NAC protein-DNA interactions as well as insight into the structural basis of NAC regulators in plants of agronomic and scientific importance.

关键词： NAC transcription factor crystal structure DNA complex senescence regulator

Synthesis and electrochemical performance of (100-x)Li7P3S11-xLi2OHBr composite solid electrolyte for all-solid-state lithium batteries

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Journal of Energy Chemistry 2020年第8期29卷 307-316,I0011页

作者： Su-yeon jung Rajesh Rajagopal Kwang-Sun Ryu Department of Chemistry University of UlsanDoowang-dongNam-gu 44776UlsanSouth Korea

Li7P3S11solid electrolytes with high lithium-ion conductivity are promising candidates for use in all-solidstate lithium ***,this electrolyte’s poor interfacial compatibility with lithium electrodes causes unstable *** this study,in order to address this problem,(100-x)Li7P3S11-xLi2OHBr(x=0,2,5,10,20,30,40,and 50)electrolytes are prepared by a high energy ball-milling technique and heat-treatment *** resulting(100-x)Li7P3S11-xLi2OHBr(x=2,5,10,20,30,40,and 50)electrolytes provide improved electrochemical performance with good cycling stability and a wide electrochemical window of up to 10 V(***/Li+).Moreover,these electrolytes have high ionic conductivity of 10-4–10-5S/cm at room ***,the 90Li7P3S11-10Li2OHBr electrolyte displays the highest conductivity of 4.4×10-4S/cm at room temperature as well as improved ***,90Li7P3S11-10Li2OHBr shows decreased interfacial resistance between the solid electrolyte and cathode electrode,which was revealed by Electrochemical Impedance Spectroscopy(EIS)*** initial discharge capacity of 90Li7P3S11-10Li2OHBr was found to be 135 m Ah/g when used in a In|solid electrolyte|Li(Ni0.6Co0.2Mn0.2)O2 all-solid-state lithium battery(ASSLB).Thus,we can conclude the addition of Li2OHBr into the Li7P3S11results in enhanced electrochemical properties.

关键词： All-solid-state lithium battery Solid electrolyte Solid sulfide electrolyte Li2OHBr Antiperovskite

Prediction of Nitrogen Diffusivity in α-ferrite Based on Thermodynamics

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Journal of Iron and Steel Research International 2015年第8期22卷 743-745页

作者： Jae-gil jung Seok-jae LEE Light Metal Division Korea Institute of Materials Science Division of Advanced Materials Engineering Research Center for Advanced Materials Development Chonbuk National University

A thermodynamic based equation to predict the diffusivity of nitrogen in α-ferrite was investigated in consideration of the equilibrium nitrogen concentration. The temperature-dependent jump distance calculated from the lattice parameter of ferrite was used to derive the frequency factor as a function of temperature. The calculation accuracy for nitrogen diffusivity using the proposed thermodynamic based equation was improved by comparing the calculation results using previous empirical equations based on Arrhenius type relationship with measured diffusivity of nitrogen for α-ferrite at different temperatures.

关键词： nitrogen diffusivity ct-ferrite thermodynamics prediction

Ventral hernia after high-intensity focused ultrasound ablation for uterine fibroids treatment:A case report

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World Journal of Clinical Cases 2022年第30期10卷 11204-11209页

作者： jung-Woo Park Hwa yeon Choi Department of Obstetrics and Gynecology Dong-A University College of MedicineBusan 49201South Korea

BACKGROUND High-intensity focused ultrasound(HIFU) ablation is a minimally invasive approach in gynecology that is used to manage uterine *** this procedure is safe and effective,adverse outcomes are becoming a major *** SUMMARY We present a case of ventral hernia that occurred as a rare and delayed complication of HIFU ablation for uterine fibroids *** patient came to the hospital with abdominal bloating that occurred 6 mo after ultrasound-guided HIFU ablation for managing uterine *** ventral hernia,which occurred due to atrophied muscle layers following the procedure,was confirmed by imaging studies and intraoperative *** required a hernia repair with mesh and hysterectomy for definitive treatment of uterine *** High-intensity ultrasound ablation should be performed only on appropriate *** should be educated about potential complications of the procedure and the possibility of subsequent ***-procedural long-term follow-up for detecting delayed adverse effects is important.

关键词： Uterine fibroids High-intensity focused ultrasound ablation Conservative treatment Ventral hernia Complication Case report

Influence of the preparation method on the catalytic activity of Mg-Al hydrotalcites as solid base catalysts

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Green Energy & Environment 2019年第3期4卷 287-292页

作者： Sungjae Park Dahye Kwon Ji yeon Kang Ji Chul jung Department of Chemical Engineering Myongji University

Mg-Al hydrotalcites were synthesized using different preparation methods(a co-precipitation method, a urea method, and a simple one) to analyze their effect on the catalytic activity of these solid base catalysts. The method strongly affected the structure of their layers(e.g., the growth and stacking of the layers, and the type of intercalated anions) and, accordingly, their catalytic activity. The Mg-Al hydrotalcite prepared by co-precipitation showed the best catalytic performance in the isomerization of glucose into fructose, due to the small crystallite size and sand rose morphology enhancing the exposure of surface active sites to reactants.

关键词： Mg-Al hydrotalcite Preparation method Base catalyst Glucose isomerization Fructose

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

Effect of an oxygen-free atmosphere during heating on anthocyanin,organic acid,and color of strawberry puree

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Food Bioscience 2022年第6期50卷 695-703页

作者： Ah-Na Kim Kyo-yeon Lee Chae-yeon Han Hyun-Jin Kim Sung-gil Choi Division of Applied Life Science Gyeongsang National UniversityJinju52828South Korea Research Group of Safety Distribution Korea Food Research InstituteWanju-gun55365Republic of Korea Division of Food Science and Technology (Institute of Agriculture and Life Sciences) Gyeongsang National UniversityJinju52828South Korea

Strawberries were ground and heated under oxygen-free condition using a specially designed device,and compared with the berries processed at atmospheric *** complete inactivation of oxidative enzymes and microorganisms were found in both *** heating without oxygen led to higher concentrations of anthocyanins and organic acids than with oxygen,resulting in higher redness and antioxidant ***,the greatest effect of anaerobic condition was observed in delphinidin-3-glycoside and ascorbic acid which are the most sensitive to oxidation in presence of ***,some nutrients which are low dependence on oxygen were degraded regardless of insufficient *** was considered that anaerobic condition may inhibit the deterioration related to only oxidation,not non-oxidative reaction during *** results implicated that dissolved oxygen in tissues may cause continuous oxidative *** summary,oxygen-free condition can confer better oxidative stability of antioxidants and color during heating of berry products.

关键词： Thermal processing Oxygen Vacuum Anthocyanin Strawberry Oxidation

Influence of undissolved second-phase particles on dynamic recrystallization behavior of Mg–7Sn–1Al–1Zn alloy during low-and high-temperature extrusions

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Journal of Materials Science & Technology 2021年第12期71卷 87-97页

作者： Hyun Ji Kim Sang-Cheol Jin Jae-gil jung Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea Implementation Research Division Korea Institute of Materials ScienceChangwon51508Republic of Korea

This study investigates the effects of fine and coarse undissolved particles in a billet of the Mg–7 Sn–1 Al–1 Zn(TAZ711)alloy on the dynamic recrystallization(DRX)behavior during hot extrusion at low and high temperatures and the resultant microstructure and mechanical properties of the *** this end,partially homogenized(PH)and fully homogenized(FH)billets are extruded at temperatures of250 and 450°*** PH billet contains fine and coarse undissolved Mg_(2) Sn particles in the interdendritic region and along the grain boundaries,*** fine particles(<1μm in size)retard DRX during extrusion at 250°C via the Zener pinning effect,and this retardation causes a decrease in the area fraction of dynamically recrystallized(DRXed)grains of the extruded *** addition,the inhomogeneous distribution of fine particles in the PH billet leads to the formation of a bimodal DRXed grain structure with excessively grown grains in particle-scarce *** contrast,in the FH billet,numerous nanosized Mg_(2) Sn precipitates are formed throughout the material during extrusion at 250°C,which,in turn,leads to the formation of small,uniform DRXed grains by the grain-boundary pinning effect of the *** the PH billet is extruded at the high temperature of 450°C,the retardation effect of the fine particles on DRX is weakened by their dissolution in theα-Mg matrix and the increased extent of thermally activated grain-boundary *** contrast,the coarse Mg_(2) Sn particles in the billet promote DRX during extrusion through the particle-stimulated nucleation phenomenon,which results in an increase in the area fraction of DRXed *** both low and high extrusion temperatures,the extruded material fabricated using the PH billet,which contains both fine and coarse undissolved particles,has a lower tensile strength than that fabricated using the FH billet,which is virtually devoid of second-phase *** lower strength of the former is attributed mai

关键词： Mg–Sn alloy Second-phase particle Extrusion Homogenization Dynamic recrystallization