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Carbon-Coated Three-Dimensional MXene/Iron Selenide Ball with Core–Shell Structure for High-Performance Potassium-Ion Batteries

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Nano-Micro Letters 2022年第1期14卷 278-294页

作者： Su Hyun Yang yun Jae lee Heemin Kang Seung-Keun Park yun Chan Kang Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul 136-713Republic of Korea Department of Advanced Materials Engineering Chung-Ang University4726 Seodong-daeroDaedeok-myeonAnseong-siGyeonggi-do 17546Republic of Korea

Two-dimensional(2D)MXenes are promising as electrode materials for energy storage,owing to their high electronic conductivity and low diffusion ***,similar to most 2D materials,MXene nanosheets easily restack during the electrode preparation,which degrades the electrochemical performance of MXene-based materials.A novel synthetic strategy is proposed for converting MXene into restacking-inhibited three-dimensional(3D)balls coated with iron selenides and *** strategy involves the preparation of Fe_(2)O_(3)@carbon/MXene microspheres via a facile ultrasonic spray pyrolysis and subsequent selenization *** 3D structuring effectively prevents interlayer restacking,increases the surface area,and accelerates ion transport,while maintaining the attractive properties of ***,combining iron selenides and carbon with 3D MXene balls offers many more sites for ion storage and enhances the structural robustness of the composite *** resultant 3D structured microspheres exhibit a high reversible capacity of 410 mAh g^(−1) after 200 cycles at 0.1 A g^(−1) in potassium-ion batteries,corresponding to the capacity retention of 97% as calculated based on 100 *** at a high current density of 5.0 A g^(−1),the composite exhibits a discharge capacity of 169 mAh g^(−1).

关键词： MXene Spray pyrolysis Iron selenide Potassium-ion batteries 3D structures

Performance of a New Ion Source for KSTAR Tokamak Plasma Heating

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Plasma Science and Technology 2014年第6期16卷 620-624页

作者： Tae-Seong KIM Seung Ho JEONG doo Hee CHANG Kwang Won lee Sang-Ryul IN Korea Atomic Energy Research Institute

In the experimental campaign of 2010 and 2011 on KSTAR, the NBI-1 system was equipped with one prototype ion source and operated successfully, providing a neutral beam power of 0.7-1.6 MW to the tokamak plasma. The new ion source planned for the 2012 KSTAR campaign had a much more advanced performance compared with the previous one. The target performance of the new ion source was to provide a neutral deuterium beam of 2 MW to the tokamak plasma. The ion source was newly designed, fabricated, and assembled in 2011. The new ion source was then conditioned up to 64 A/100 keV over a 2-hour beam extraction and performance tested at the NB test stand （NBTS） at the Korea Atomic Energy Research Institute （KAERI） in 2012. The measured optimum perveance at which the beam divergence is a minimum was about 2.5μP, and the minimum beam divergent angle was under 1.0° at 60 keV. These results indicate that the 2.0 MW neutral beam power at 100 keV required for the heating of plasma in KSTAR can be delivered by the installation of the new ion source in the KSTAR NBI-1 system.

关键词： NBI ion source KSTAR neutral beam plasma heating positive based ion

GIGANTEA Shapes the Photoperiodic Rhythms of Thermomorphogenic Growth in Arabidopsis

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Molecular Plant 2020年第3期13卷 459-470页

作者： Young-Joon Park Jae Young Kim June-Hee lee Byoung-doo lee Nam-Chon Paek Chung-Mo Park Department of Chemistry Seoul National UniversitySeoul 08826Korea Department of Plant Science Seoul National UniversitySeoul 08826Korea Plant Genomics and Breeding Institute Seoul National UniversitySeoul 08826Korea These authors contributed equally to this article

Plants maintain their internal temperature under environments with fluctuating temperatures by adjusting their morphology and architecture,an adaptive process termed ***,the rhythmic patterns of plant thermomorphogenesis are governed by day-length ***,it remains elusive how thermomorphogenic rhythms are regulated by ***,we show that warm temperatures enhance the accumulation of the chaperone GIGANTEA(Gl),which thermostabilizes the DELLA protein,REPRESSOR OF ga1-3(RGA),under long days,thereby attenuating PHYTOCHROME INTERACTING FACTOR 4(PIF4)-mediated *** contrast,under short days,when Gl accumulation is reduced,RGA is readily degraded through the gibberellic acid-mediated ubiquitination-proteasome pathway,promoting thermomorphogenic *** data indicate that the GI-RGA-PIF4 signaling module enables plant thermomorphogenic responses to occur in a day-length-dependent *** propose that the Gl-mediated integration of photoperiodic and temperature information shapes thermomorphogenic rhythms,which enable plants to adapt to diel fluctuations in day length and temperature during seasonal transitions.

关键词： thermomorphogenesis day length Gl RGA PIF4

Alleviating Interfacial Recombination of Heterojunction Electron Transport Layer via Oxygen Vacancy Engineering for Efficient Perovskite Solar Cells Over 23%

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Energy & Environmental Materials 2023年第2期6卷 311-322页

作者： Yohan Ko Taemin Kim Chanyong lee Changhyun lee Yong Ju yun Yongseok Jun Graduate School of Energy and Environment(KU-KIST Green School) Korea UniversitySeoul 02841Korea

Electron transport layer(ETL)is pivotal to charge carrier transport for PSCs to reach the Shockley-Queisser *** study provides a fundamental understanding of heterojunction electron transport layers(ETLs)at the atomic level for stable and efficient perovskite solar cells(PSCs).The bilayer structure of an ETL composed of SnO_(2) on TiO_(2) was examined,revealing a critical factor limiting its potential to obtain efficient *** of oxygen vacancies in the TiO_(2) underlayer via an annealing process is found to induce manipulated band offsets at the interface between the TiO_(2) and SnO_(2) ***-depth electronic investigations of the bilayer structure elucidate the importance of the electronic properties at the interface between the TiO_(2) and SnO_(2) *** apparent correlation in hysteresis phenomena,including current density-voltage(J-V)curves,appears as a function of the type of band *** functional theory calculations reveal the intimate relationship between oxygen vacancies,deep trap states,and charge transport efficiency at the interface between the TiO_(2) and SnO_(2) *** formation of cascade band alignment via control over the TiO_(2) underlayer enhances device performance and suppresses *** performance exhibits a power conversion efficiency(PCE)of 23.45%with an open-circuit voltage(V_(oc))of 1.184 V,showing better device stability under maximum power point tracking compared with a staggered bilayer under one-sun continuous illumination.

关键词： electron transport bilayer heterojunction bilayers interfacial defect oxygen vacancy engineering perovskite solar cells

The difference of morphological characteristics and population structure in PAO and DPAO granular sludges

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Journal of Environmental Sciences 2019年第2期31卷 388-402页

作者： Geumhee yun Hansaem lee Yongsuk Hong Sungpyo Kim Glen T.Daigger Zuwhan yun Department of Environmental Engineering Korea University Hyundai Engineering & Construction Co. Ltd. Department of Civil and Environmental Engineering University of Michigan

We examined how long-term operation of anaerobic–oxic and anaerobic–anoxic sequencing batch reactors(SBRs) affects the enhanced biological phosphorus removal(EBPR)performance and sludge characteristics. The microbial characteristics of phosphorus accumulating organism(PAO) and denitrifying PAO(DPAO) sludge were also analyzed through a quantitative analysis of microbial community structure. Compared with the initial stage of operation characterized by unstable EBPR, both PAO and DPAO SBR produced a stable EBPR performance after about 100-day operation. From day 200 days(DPAO SBR)and 250 days(PAO SBR) onward, sludge granulation was observed, and the average granule size of DPAO SBR was approximately 5 times larger than that of PAO SBR. The DPAO granular sludge contained mainly rod-type microbes, whereas the PAO granular sludge contained coccus-type microbes. Fluorescence in situ hybridization analysis revealed that a high ratio of Accumulibacter clade I was found only in DPAO SBR, revealing the important role of this organism in the denitrifying EBPR system. A pyrosequencing analysis showed that Accumulibacter phosphatis was present in PAO sludge at a high proportion of 6%,whereas it rarely observed in DPAO sludge. Dechloromonas was observed in both PAO sludge(3.3%) and DPAO sludge(3.2%), confirming that this organism can use both O_2 and NO_3^- as electron acceptors. Further, Thauera spp. was identified to have a new possibility as denitrifier capable of phosphorous uptake under anoxic condition.

关键词： Accumulibacter phosphatis Dechloromonas Granulation Pyrosequencing Thauera

RADIALLY SYMMETRIC SOLUTIONS FOR QUASILINEAR ELLIPTIC EQUATIONS INVOLVING NONHOMOGENEOUS OPERATORS IN AN ORLICZ-SOBOLEV SPACE SETTING

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Acta Mathematica Scientia 2020年第6期40卷 1679-1699页

作者： Jae-Myoung KIM yun-Ho KIM Jongrak lee Department of Mathematics Education Andong National UniversityAndong 36729Republic of Korea Department of Mathematics Education Sangmyung UniversitySeoul 03016Republic of Korea Department of Mathematics Jeju National UniversityJeju 63243Republic of Korea

We investigate the following elliptic equations:⎧⎩⎨−M(∫R Nϕ(|∇u|2)dx)div(ϕ′(|∇u|2)∇u)+|u|α−2 u=λh(x,u),u(x)→0,as|x|→∞,in R N,where N≥2,1 详细信息

We investigate the following elliptic equations:⎧⎩⎨−M(∫R Nϕ(|∇u|2)dx)div(ϕ′(|∇u|2)∇u)+|u|α−2 u=λh(x,u),u(x)→0,as|x|→∞,in R N,where N≥2,1

关键词： radial solution quasilinear elliptic equations variational methods Orlicz-Sobolev spaces

Potentiating activity of rhein in targeting of resistance genes in methicillin-resistant Staphylococcus aureus

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Asian Pacific Journal of Tropical Medicine 2019年第1期12卷 14-18页

作者： Ryong Gong Dae Young lee Jae Won lee doo Jin Choi Geum-Soog Kim Sang Hyuk lee Young-Seob lee Department of Herbal Crop Research National Institute of Horticultural & Herbal Science Rural Development Administration

Objective: To investigate the synergistic effect between rhein(RHE) and oxacillin against Staphylococcus aureus(MRSA) at the gene level. Method: A minimum inhibitory concentration and checkerboard dilution test were conducted to evaluate antibacterial activity. Reverse transcriptase polymerase chain reaction was conducted to investigate the gene expressions. Results: RHE exhibited a minimum inhibitory concentration of 62.5-250.0 μg/mL against various MRSA strains and the reference strain, respectively. As revealed by the checkerboard assay, a combination of RHE and oxacillin exhibited synergistic or partially synergistic effects against MRSA strains. RHE decreased the expressions of mecA/blaZ in a dose-dependent manner. RHE also decreased the expressions of the regulator genes mecI/blaI and mecR1/blaR1. Conclusions: We suggest that RHE affects the activity of mecR1/blaR1, which is located in the cell membrane of MRSA and results in the suppression of mecA/mecI/mecR1 and blaZ/blaI/blaR1 gene expressions.

关键词： Antimicrobials Mechanism of action Staphylococcus aureus Polymerase chain reaction

Unraveling the electrocatalytically active sites and stability of Co&Co oxides on nanocarbon for oxygen evolution reaction in acid solution

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Journal of Energy Chemistry 2020年第10期29卷 8-13页

作者： Yansong Zhu Tianran Zhang Tao An yun Zong Jim Yang lee Faculty of Pharmacy Shenyang Pharmaceutical UniversityShenyang 110016LiaoningChina Department of Chemical and Biomolecular Engineering National University of SingaporeSingapore Institute of Materials Research and Engineering(IMRE) Singapore

The oxygen evolution reaction(OER)in acid solution is a significant challenge for non-precious metal electrocatalysts based on the transition metals although they have shown good OER performance in alkaline *** this study,we synthesized the electrocatalysts containing two or three Co species(Co,CoO and Co3O4)nanoparticles on porous graphitic carbon(PGC)nanosheets which were prepared by a facile and low-cost synthesis where Co(NO3)2•6H2O and glucose were pyrolyzed in the presence of sodium chloride *** Co3O4-dominated catalyst as-prepared,Co3O4/PGC,is OER active in acid solution(1.74 V at a current density of 10 mA cm^−2).We identified the OER active sites in the catalyst to be the Co3O4 nanoparticles rather than carbon-coated *** comparative studies of the varied catalysts,we also proved that Co3O4 is catalytically more active than Co and *** Co3O4/PGC catalyst,however,lost almost of all its activity after 100 voltammetric cycles in the 1.2-1.8 V voltage *** the catalyst stability was examined potentiostatically at different potentials,the catalyst showed good stability at 1.4 *** stability study also revealed the mechanism of the catalyst instability in acid was caused by Co3O4 reduction below 1.4 V and by Co3O4 oxidation above 1.4 V.1.4 V is therefore a unique potential where Co3O4 nanoparticles are neither oxidized nor reduced to be susceptible to acid dissolution.

关键词： Non-precious metal Active sites Oxygen evolution reaction Acid Stability

Extraordinary Ultrahigh-Capacity and Long Cycle Life Lithium-Ion Batteries Enabled by Graphitic Carbon Nitride-Perylene Polyimide Composites

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