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Microstructure analyses and phase-field simulation of partially divorced eutectic solidification in hypoeutectic Mg-Al Alloys

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Journal of Magnesium and Alloys 2022年第6期10卷 1672-1679页

作者： joo-Hee Kang Jiwon Park Kyung song Chang-seok Oh Oleg Shchyglo Ingo Steinbach Korea Institute of Materials Science Changwon 51508Republic of Korea Interdisciplinary Centre for Advanced Materials Simulation Ruhr-University Bochum44801 BochumGermany

In this study the partially divorced eutectic microstructure ofα-Mg andβ-Mg17Al12was investigated by electron backscatter diffraction,transmission electron microscopy,and phase-field modeling in hypoeutectic Mg-Al *** orientation relationships between the individual eutecticαgrains,eutecticβphase,and primaryαgrains were *** the amount of eutectic morphology is primarily determined by the Al content,the in-depth microstructure analyses and the phase-field simulation suggest non-interactive nucleation and growth of eutecticαphase in theβphase grown on the interdendritic primaryα***,phase-field simulations showed a preferred nucleation sequence where theβphase nucleates first and subsequently triggers the nucleation of eutecticαphase at the movingβphase solidification front,which supports the microstructural analysis results.

关键词： Mg-Al alloy Partially divorced eutectic Solidification Electron backscatter diffraction Phase-Field modeling

Early expressions of hypoxia-inducible factor 1alpha and vascular endothelial growth factor increase the neuronal plasticity of activated endogenous neural stem cells after focal cerebral ischemia

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Neural Regeneration Research 2014年第9期9卷 912-918页

作者： Seung song Jong-Tae Park joo Young Na Man-seok Park Jeong-Kil Lee Min-Cheol Lee Hyung-seok Kim Department of Forensic Medicine Chonnam National University Medical School Department of Neurology Chonnam National University Medical School Department of Neurosurgery Chonnam National University Medical School Department of Pathology Chonnam National University Medical School

Endogenous neural stem cells become ＂activated＂ after neuronal injury, but the activation sequence and fate of endogenous neural stem cells in focal cerebral ischemia model are little known. We evaluated the relationships between neural stem cells and hypoxia-inducible factor-1α and vascular endothelial growth factor expression in a photothromobotic rat stroke model using immunohistochemistry and western blot analysis. We also evaluated the chronological changes of neural stem cells by 5-bromo-2′-deoxyuridine（BrdU） incorporation. Hypoxia-inducible factor-1α expression was initially increased from 1 hour after ischemic injury, followed by vascular endothelial growth factor expression. Hypoxia-inducible factor-1α immunoreactivity was detected in the ipsilateral cortical neurons of the infarct core and peri-infarct area. Vascular endothelial growth factor immunoreactivity was detected in bilateral cortex, but ipsilateral cortex staining intensity and numbers were greater than the contralateral cortex. Vascular endothelial growth factor immunoreactive cells were easily found along the peri-infarct area 12 hours after focal cerebral ischemia. The expression of nestin increased throughout the microvasculature in the ischemic core and the peri-infarct area in all experimental rats after 24 hours of ischemic injury. Nestin immunoreactivity increased in the subventricular zone during 12 hours to 3 days, and prominently increased in the ipsilateral cortex between 3–7 days. Nestin-labeled cells showed dual differentiation with microvessels near the infarct core and reactive astrocytes in the peri-infarct area. BrdU-labeled cells were increased gradually from day 1 in the ipsilateral subventricular zone and cortex, and numerous BrdU-labeled cells were observed in the peri-infarct area and non-lesioned cortex at 3 days. BrdU-labeled cells rather than neurons, were mainly co-labeled with nestin and GFAP. Early expressions of hypoxia-inducible factor-1α and vascular endothelial gr

关键词： nerve regeneration brain ischemia neural stem cell neural precursor cell hypoxia-inducible factor 1α vascular endothelial growth factor microenvironment photothrombosis neural regeneration

Pyruvate dehydrogenase kinase is a negative regulator of interleukin-10 production in macrophages

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Journal of Molecular Cell Biology 2020年第7期12卷 543-555页

作者： Yi Rang Na Daun Jung Juha song Jong-Wan Park Jung joo Hong Seung Hyeok seok Macrophage Lab Department of Microbiology and Immunology and Institute of Endemic DiseaseSeoul National University College of MedicineChongno-guSeoul 03080Republic of Korea Department of Biomedical Science BK21-Plus Education ProgramSeoul National University College ofMedicineJongno-guSeoul 03080Republic of Korea Department of Pharmacology Seoul National University College of MedicineJongno-guSeoul 03080Republic of Korea Cancer Research Institute and Ischemic/Hypoxic Disease Institute Seoul National University College ofMedicineJongno-guSeoul 03080Republic of Korea National Primate Research Center Korea Research Institute of Bioscience and BiotechnologyCheongju 28116Republic of Korea

Interleukin-10(IL-10)is the most potent anti-inflammatory cytokine in the body and plays an essential role in determining outcomes of many inflammatory *** metabolism is a critical determinant of immune cell function;however,it is currently unclear whether metabolic processes are specifically involved in IL-10 *** this study,we aimed to find the central metabolic molecule regulating IL-10 production of macrophages,which are the main producers of *** analysis identified that metabolic changes were predominantly enriched in Kupffer cells at the early inflammatory phase of a mouse endotoxemia *** them,pyruvate dehydrogenase kinase(PDK)-dependent acute glycolysis was negatively involved in IL-10 *** or knockdown of PDK selectively increased macrophage IL-10 ***,PDK inhibition increased IL-10 production via profound phosphorylation of adenosine monophosphate(AMP)-activated protein kinase alpha 1(AMPKα1)by restricting glucose uptake in lipopolysaccharide-stimulated ***α1 consequently activated p38 mitogen-activated protein kinase,c-Jun N-terminal kinase,and cyclic AMP-responsive element-binding protein to regulate IL-10 *** study uncovers a previously unknown regulatory mechanism of IL-10 in activated macrophages involving an immunometabolic function of PDK.

关键词： macrophage pyruvate dehydrogenase kinase AMP-activated protein kinase interleukin-10

Application of artificial intelligence in gastroenterology

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World Journal of Gastroenterology 2019年第14期25卷 1666-1683页

作者： Young joo Yang Chang seok Bang Department of Internal Medicine Hallym University College of Medicine

Artificial intelligence(AI) using deep-learning(DL) has emerged as a breakthrough computer technology. By the era of big data, the accumulation of an enormous number of digital images and medical records drove the need for the utilization of AI to efficiently deal with these data, which have become fundamental resources for a machine to learn by itself. Among several DL models, the convolutional neural network showed outstanding performance in image analysis. In the field of gastroenterology, physicians handle large amounts of clinical data and various kinds of image devices such as endoscopy and ultrasound. AI has been applied in gastroenterology in terms of diagnosis,prognosis, and image analysis. However, potential inherent selection bias cannot be excluded in the form of retrospective study. Because overfitting and spectrum bias(class imbalance) have the possibility of overestimating the accuracy,external validation using unused datasets for model development, collected in a way that minimizes the spectrum bias, is mandatory. For robust verification,prospective studies with adequate inclusion/exclusion criteria, which represent the target populations, are needed. DL has its own lack of *** interpretability is important in that it can provide safety measures, help to detect bias, and create social acceptance, further investigations should be performed.

关键词： Artificial intelligence Convolutional neural network Deep-learning Computer-assisted Gastroenterology Endoscopy

Effects of an Urban Park and Residential Area on the Atmospheric CO_2 Concentration and Flux in Seoul,Korea

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Advances in Atmospheric Sciences 2013年第2期30卷 503-514页

作者： Moon-Soo PARK Seung Jin joo Chang seok LEE Center for Atmospheric and Environmental Modeling Seoul 151 919Korea Life and Environmental Engineering Seoul Women's UniversitySeoul 139 774Korea

The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 2011）, and the late-growing season （22-24 September 2011） were analyzed. The CO2 concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season （early spring） and a minimum value during the growing season （summer）. The CO2 flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO2 flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600-1000 LST and 1800-2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.

关键词： C02 concentration C02 flux Seoul urban forest urban residential region

Highly Stable Silicon–Carbon–Nitrogen Composite Anodes from Silsesquiazane for Rechargeable Lithium-Ion Battery

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Journal of Materials Science & Technology 2016年第3期32卷 195-199页

作者： Yong seok Kim Yong L.joo Young-Je Kwark School of Chemical & Biomolecular Engineering Cornell University Department of Organic Materials and Fiber Engineering Soongsil University

Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.

关键词： Polymer-derived ceramics Silsesquiazane Lithium ion battery Lithium ion conductivity

Destruction of methylphosphonic acid in a supercritical water oxidation bench-scale double wall reactor

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Journal of Environmental Sciences 2011年第4期23卷 545-552页

作者： Bambang Veriansyah Eun-seok song Jae-Duck Kim Supercritical Fluid Research Laboratory Korea Institute of Science and Technology (KIST) 39-1 Hawolgok-dong Seoungbuk-gu Seoul 136-791 Korea

The destruction of methylphosphonic acid （MPA）, a final product by hydrolysis/neutralization of organophosphorus agents such as sarin and VX （O-ethyl S-[2-（diisopropylamino）ethyl] methylphosphonothionate）, was investigated in a a bench-scale, continuous concentric vertical double wall reactor under supercritical water oxidation condition. The experiments were conducted at a temperature range of 450–600°C and a fixed pressure of 25 MPa. Hydrogen peroxide was used as an oxidant. The destruction efficiency （DE） was monitored by analyzing total organic carbon （TOC） and MPA concentrations using ion chromatography on the liquid effluent samples. The results showed that the DE of MPA up to 99.999% was achieved at a reaction temperature of 600°C, oxygen concentration of 113% storichiometric requirement, and reactor residence time of 8 sec. On the basis of the data derived from experiments, a global kinetic rate equation for the DE of MPA and DE of TOC were developed by nonlinear regression analysis. The model predictions agreed well with the experimental data.

关键词： supercritical water oxidation destruction efficiency methylphosphonic acid reaction kinetic nonlinear regression

A dynamic infiltration technique to synthesize nanolayered cathodes for high performance and robust solid oxide fuel cells

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Journal of Energy Chemistry 2022年第7期31卷 201-210,I0006页

作者： Saeed Ur Rehman Ho-Seon song Hye-Sung Kim Muhammad Haseeb Hassan Dong-Woo Joh Rak-Hyun song Tak-Hyoung Lim Jong-Eun Hong seok-joo Park Seung-Bok Lee High Temperature Energy Conversion Laboratory Korea Institute of Energy Research152Gajeong-roYuseong-gu.Daejeon34129.Republic of Korea Department of Advanced Energy and System Engineering University of Science and Technology.217 Gajeong-ro.Yuseong-gu.Daejeon 34113.Republicof Korea

Solution infiltration is a popular technique for the surface modification of solid oxide fuel cell(SOFC)***,the synthesis of nanostructured SOFC cathodes by infiltration is a tedious process that often requires several infiltration and high temperature(≥500℃)calcination ***,fabricating large-area nanostructured cathodes via infiltration still requires serious ***,we propose a facile and scalable urea assisted ultrasonic spray infiltration technique for nanofabrication of SOFC *** is demonstrated that by using urea as a precipitating agent,the calcination after each infiltration cycle can be omitted and the next infiltration can be performed just after a drying step(≤100℃).Finally,the precipitates can be converted into a desired catalyst phase in single calcination thus,a nanostructured cathode can be fabricated in a much faster *** is also shown that the low calcination temperature of the cathode(≤900℃)can produce highly durable SOFC performance even without employing a Ce_(0.9)Gd_(0.1)O_(2)(GDC)diffusion barrier layer which provides the ease of SOFC *** coupling with an ultrasonic spray technique,the urea assisted infiltration can be scaled up for any desired cathode ***_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3) nanolayered cathode was fabricated and it was characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),and transmission electron microscopy(TEM)*** showed the formation of a nanolayer cathode just after 5 cycles of the urea assisted infiltration while the XRD and TEM confirmed the phase and stoichiometric uniformity of the 100 nm cathode *** effectiveness of the newly developed technique was further verified by the stable operation of a GDC buffer layer free SOFC having an active cathode area of 25 cm^(2) during a 1200 h durability *** research outcomes propose urea assisted ultrasonic spray infiltration as a facile,scalable,and commercially viable method

关键词： Solid oxide fuel cell(SOFC) Cathode Infiltration Nanolayer Nanofabrication GDC barrier layer free SOFC

Recent Advances in Carbon-Based Current Col lectors/Hosts for Alkali Metal Anodes

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Energy & Environmental Materials 2023年第5期6卷 112-141页

作者： Guanyao Wang Chan song Jiaqi Huang Ho seok Park School of Chemical Engineering Sungkyunkwan University2066SeoburoJangan-guSuwon 440-746Korea School of Chemistry and Molecular Engineering Nanjing Tech UniversityNanjing 211816China School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Department of Health Sciences and Technology Samsung Advanced Institute for Health Sciences and Technology(SAIHST)Sungkyunkwan University2066SeoburoJangan-guSuwon 440-746Korea SKKU Advanced Institute of Nano Technology(SAINT) Sungkyunkwan University2066SeoburoJangan-guSuwon 440-746Korea

The urgent demand for high-energy-density storage systems evokes the research upsurge on the alkali metal batteries with high theoretical ***,the utilization of alkali metal anodes,including Li,Na,and K,is significantly hindered by notorious dendrite growth,undesirable corrosion,and unstable solid electrolyte *** order to resolve these issues,the carbon materials for the rational design of current collector/host that can regulate the plating/stripping behavior of alkali metal have been *** carbon-based current collectors/hosts are featured with many pivotal advantages,including mechanical integrity to accommodate the volume change,superior electronic/ionic conductivity,large available surface area,and rich functionalization chemistries to increase the affinity to alkali *** this review,the recent progress on various dimensional carbon-based current collectors/hosts with different chemical components in stabilizing the alkali metal anodes through the regulation of initial deposition and subsequent growth behavior during plating/stripping process is *** nanostructured carbon scaffolds with self-affinity to alkali metals,as well as the carbon frameworks with internal/external affinitive sites to alkali metals,catalogued by various dimensions,are discussed in this ***,these appealing strategies based on the carbon-based current collectors/hosts can provide a paradigm for the realization of high-energy-density alkali metal batteries.

关键词： carbon-based materials current collectors energy density hosts metal anodes