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Segmented tomographic evaluation of structural degradation of carbon support in proton exchange membrane fuel cells

Journal of Energy Chemistry 2022年第11期31卷 359-367,I0010页

作者： Jung A.Hong Min-Hyoung Jung sung Yong Cho Eun-Byeol Park Daehee Yang Young-Hoon Kim Sang-Hyeok Yang woo-sung jang Jae Hyuck jang Hyo June Lee sungchul Lee Hu Young Jeong Young-Min Kim Department of Energy Science Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Fuel Cell Core Parts Development Cell Hyundai Mobis Co.Ltd.Uiwang 16082Republic of Korea Electron Microscopy&Spectroscopy Team Korea Basic Science Institute(KBSI)Daejeon 34133Republic of Korea Graduate School of Semiconductor Materials and Devices Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919Republic of Korea

The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon *** increasing degradation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells(PEM-FCs).This phenomenon can be explained by performing 3D tomographic analysis at the ***,conventional tomographic approaches which present limited experimental feasibility,cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus ***,a reliable methodology is required for the 3D geometrical evaluation of the carbon ***,we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high *** approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area,pore size distribution,and their 3D *** geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced *** information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the development of stable PEM-FC electrodes.

关键词： Electron tomography Fuel cell Proton exchange membrane Membrane electrode assembly Carbon corrosion

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Ionizing terahertz waves with 260 MV/cm from scalable optical rectification

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Light(Science & Applications) 2024年第6期13卷 1075-1087页

作者： Hyeongmun Kim Chul Kang Dogeun jang Yulan Roh Sang Hwa Lee Joong wook Lee Jae Hee sung Seong Ku Lee Ki-Yong Kim Advanced Photonics Research Institute GISTGwangju61005Korea Department of Physics and Optoelectronics Convergence Research Center Chonnam National UniversityGwangju61186Korea Pohang Accelerator Laboratory POSTECHPohang37673Korea Center for Relativistic Laser Science Institute for Basic ScienceGwangju61005Korea Institute for Research in Electronics and Applied Physics Department of PhysicsUniversity of MarylandCollege ParkMaryland20742USA

Terahertz(THz)waves,known as non-ionizing radiation owing to their low photon energies,can actually ionize atoms and molecules when a sufficiently large number of THz photons are concentrated in time and ***,we demonstrate the generation of ionizing,multicycle,15-THz waves emitted from large-area lithium niobate crystals via phase-matched optical rectification of 150-terawatt laser pulses.A complete characterization of the generated THz waves in energy,pulse duration,and focal spot size shows that the field strength can reach up to 260 megavolts per *** particular,a single-shot THz interferometer is employed to measure the THz pulse duration and spectrum with complementary numerical *** intense THz pulses are irradiated onto various solid targets to demonstrate THz-induced tunneling ionization and plasma *** study also discusses the potential of nonperturbative THz-driven ionization in gases,which will open up new opportunities,including nonlinear and relativistic THz physics in plasma.

关键词： optical interferometer matched

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Unraveling the Harmonious Coexistence of Ruthenium States on a Self-Standing Electrode for Enhanced Hydrogen Evolution Reaction

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Energy & Environmental Materials 2024年第6期7卷 303-311页

作者： Joonhee Ma Jin Hyuk Cho Chaehyeon Lee Moon sung Kang sungkyun Choi Ho Won jang Sang Hyun Ahn Seoin Back Soo Young Kim Department of Materials Science and Engineering Korea UniversitySeoul 02841Korea Department of Chemical and Biomolecular Engineering Institute of Emergent MaterialsSogang UniversitySeoul 04107Korea Department of Cogno-Mechatronics Engineering College of Nanoscience and NanotechnologyPusan National UniversityBusan 46241Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Korea School of Chemical Engineering and Material Science Chung-Ang UniversitySeoul 06974Korea

The development of cost-effective,highly efficient,and durable electrocatalysts has been a paramount pursuit for advancing the hydrogen evolution reaction(HER).Herein,a simplified synthesis protocol was designed to achieve a self-standing electrode,composed of activated carbon paper embedded with Ru single-atom catalysts and Ru nanoclusters(ACP/Ru_(SAC+C))via acid activation,immersion,and high-temperature *** initio molecular dynamics(AIMD)calculations are employed to gain a more profound understanding of the impact of acid activation on carbon ***,the coexistence states of the Ru atoms are confirmed via aberration-corrected scanning transmission electron microscopy(AC-STEM),X-ray photoelectron spectroscopy(XPS),and X-ray absorption spectroscopy(XAS).Experimental measurements and theoretical calculations reveal that introducing a Ru single-atom site adjacent to the Ru nanoclusters induces a synergistic effect,tuning the electronic structure and thereby significantly enhancing their catalytic ***,the ACP/Ru_(SAC+C)exhibits a remarkable turnover frequency(TOF)of 18 s^(−1)and an exceptional mass activity(MA)of 2.2 A mg^(−1),surpassing the performance of conventional Pt *** self-standing electrode,featuring harmoniously coexisting Ru states,stands out as a prospective choice for advancing HER catalysts,enhancing energy efficiency,productivity,and selectivity.

关键词： electrocatalysis electronic coupling effect hydrogen evolution reaction selfstanding electrode

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Dimensionality-driven metal to Mott insulator transition in two-dimensional 1T-TaSe2

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National Science Review 2024年第3期11卷 108-118页

作者： Ning Tian Zhe Huang Bo Gyu jang Shuaifei Guo Ya-Jun Yan Jingjing Gao Yijun Yu Jinwoong Hwang Cenyao Tang Meixiao Wang Xuan Luo Yu Ping Sun Zhongkai Liu Dong-Lai Feng Xianhui Chen sung-Kwan Mo Minjae Kim Young-woo Son Dawei Shen Wei Ruan Yuanbo Zhang State Key Laboratory of Surface Physics New Cornerstone Science Laboratory and Department of PhysicsFudan University Shanghai Qi Zhi Institute Shanghai Research Center for Quantum Sciences Institute for Nanoelectronic Devices and Quantum Computing Fudan University Zhangjiang Fudan International Innovation Center Fudan University State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology(SIMIT)Chinese Academy of Sciences School of Physical Science and Technology ShanghaiTech University Korea Institute for Advanced Study School of Emerging Technology and Department of Physics University of Science and Technology of China Advanced Light Source Lawrence Berkeley National Laboratory ShanghaiTech Laboratory for Topological Physics Key Laboratory of Materials Physics Institute of Solid State Physics Hefei Institutes of Physical ScienceChinese Academy of Sciences High Magnetic Field Laboratory Hefei Institutes of Physical Science Chinese Academy of Sciences Collaborative Innovation Centre of Advanced Microstructures Nanjing University Department of Physics University of Science and Technology of China and Key Laboratory of Strongly Coupled Quantum Matter Physics Chinese Academy of Sciences National Synchrotron Radiation Laboratory University of Science and Technology of China

Two-dimensional materials represent a major frontier for research into exotic many-body quantum phenomena. In the extreme two-dimensional limit, electron-electron interaction often dominates over other electronic energy scales, leading to strongly correlated effects such as quantum spin liquid and unconventional *** dominance is conventionally attributed to the lack of electron screening in the third dimension. Here, we discover an intriguing metal to Mott insulator transition in 1T-TaSe2that defies conventional wisdom. Specifically, we find that dimensionality crossover, instead of reduced screening, drives the transition in atomically thin 1T-TaSe2. A dispersive band crossing the Fermi level is found to be responsible for the bulk metallicity in the material. Reducing the dimensionality,however, effectively quenches the kinetic energy of these initially itinerant electrons, and drives the material into a Mott insulating *** dimensionality-driven metal to Mott insulator transition resolves the long-standing dichotomy between metallic bulk and insulating surface of 1T-TaSe2. Our work further reveals a new pathway for modulating two-dimensional materials that enables exploring strongly correlated systems across uncharted parameter space.

关键词： two-dimensional materials 1T-TaSe2 dimensionality crossover metal to Mott insulator transition

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Harnessing SARS-CoV-2-specific CD8^(+)T cells to kill target tumor cells for cancer immunotherapy

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Cancer Communications 2024年第1期44卷 173-177页

作者： Keunok Jung Deok-Han Ko Jeong-Yun jang Young Rong Kim Jung Yeon Heo Yong-sung Kim Department of Allergy and Clinical Immunology Ajou University School of MedicineSuwonRepublic of Korea Department of Molecular Science and Technology Ajou UniversitySuwonRepublic of Korea Department of Infectious Diseases Ajou University School of MedicineSuwonRepublic of Korea

Dear Editor,During the coronavirus disease 2019(COVID-19)pan-demic era,many individuals were naturally infected with or vaccinated against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),resulting in the p... 详细信息

关键词： acute respiratory immunotherapy

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Regulation of sleep by astrocytes in the hypothalamic ventrolateral preoptic nucleus

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Neural Regeneration Research 2025年第4期20卷 1098-1100页

作者： Jae-Hong Kim Ruqayya Afridi Il-sung jang Maan Gee Lee Kyoungho Suk Brain Korea 21 four KNU Convergence Educational Program of Biomedical Sciences for Creative Future Talents School of MedicineKyungpook National UniversityDaeguRepublic of Korea Department of Pharmacology School of MedicineKyungpook National UniversityDaeguRepublic of Korea Department of Pharmacology School of DentistryKyungpook National UniversityDaeguRepublic of Korea Brain Science&Engineering Institute Kyungpook National UniversityDaeguRepublic of Korea

Astrocytes are functionally dynamic cells that support neurons in multiple ways throughout an organism’s *** astrocytic regulation of neuronal activity has been increasingly recognized in recent *** are now recognized as playing a more complex role than mere bystanders in the central nervous ***,their role in regulating the sleep neurocircuitry is not well *** this perspective,we highlight the role of astrocytes in sleep modulation,with a particular focus on regulatory mechanisms related to the ventrolateral preoptic nucleus(VLPO)of the *** briefly discuss recent literature reporting the role of VLPO astrocytes in regulating sleep-associated behaviors.

关键词： sleep ventrolateral astrocytes

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Enhancing BiVO_(4)photoanode performance by insertion of an epitaxial BiFeO_(3)ferroelectric layer

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Journal of Energy Chemistry 2024年第2期89卷 71-78,I0003页

作者： Haejin jang Yejoon Kim Hojoong Choi Jiwoong Yang Yoonsung Jung sungkyun Choi Donghyeon Lee Ho Won jang Sanghan Lee School of Materials Science and Engineering Gwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea

BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical ***,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical *** address this,various modifications have been attempted,including the use of ferroelectric *** materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole *** this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of *** self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge *** a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)*** results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.

关键词： Photoelectrochemical Photoanode BiVO_(4) Ferroelectric materials BiFeO_(3)

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Non-interleaved chiral metasurfaces and neural networks enhance the spatial resolution of polarimetry

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Light(Science & Applications) 2024年第3期13卷 396-398页

作者： Jaewon jang Minsu Park Yeonsang Park Department of Physics Chungnam National UniversityDaejeon 34134Korea Institute of Quantum Systems Chungnam National UniversityDaejeon 34134Korea

Non-interleaved chiral metasurfaces for high-spatial-resolution polarimetry are proposed and ***,a convolutional neural network is incorporated to analyze interferometric images with the polarization state of light,an... 详细信息

关键词： parameters chiral resolution

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Real-Time Tunable Gas Sensing Platform Based on SnO_(2) Nanoparticles Activated by Blue Micro-Light-Emitting Diodes

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Nano-Micro Letters 2024年第12期16卷 103-119页

作者： Gi Baek Nam Jung-El Ryu Tae Hoon Eom Seung Ju Kim Jun Min Suh Seungmin Lee sungkyun Choi Cheon woo Moon Seon Ju Park Soo Min Lee Byungsoo Kim sung Hyuk Park Jin wook Yang Sangjin Min Sohyeon Park sung Hwan Cho Hyuk Jin Kim Sang Eon Jun Tae Hyung Lee Yeong Jae Kim Jae Young Kim Young Joon Hong Jong-In Shim Hyung-Gi Byun Yongjo Park Inkyu Park Sang-Wan Ryu Ho Won jang Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Research Laboratory of Electronics Department of Mechanical EngineeringMassachusetts Institute of TechnologyCambridgeMA 02139USA Ming Hsieh Department of Electrical and Computer Engineering University of Southern CaliforniaLos AngelesCA 90089USA Department of Display Materials Engineering Soonchunhyang UniversityAsan 31538Republic of Korea Department of Photonics and Nanoelectronics BK21 FOUR ERICA-ACE CenterHanyang University ERICAAnsan 15588Republic of Korea Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Department of Electronics Information and Communication EngineeringKangwon National UniversitySamcheok 25913Republic of Korea Advance Institute of Convergence Technology Seoul National UniversitySuwon 16229Republic of Korea Department of Mechanical Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Department of Physics Chonnam National UniversityGwangju 500-757Republic of Korea

Micro-light-emitting diodes(μLEDs)have gained significant interest as an activation source for gas sensors owing to their advantages,including room temperature operation and low power ***,despite these benefits,challenges still exist such as a limited range of detectable gases and slow *** this study,we present a blueμLED-integrated light-activated gas sensor array based on SnO_(2)nanoparticles(NPs)that exhibit excellent sensitivity,tunable selectivity,and rapid detection with micro-watt level power *** optimal power forμLED is observed at the highest gas response,supported by finite-difference time-domain ***,we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO_(2)*** noble metals induce catalytic interaction with reducing gases,clearly distinguishing NH3,H2,and ***-time gas monitoring based on a fully hardwareimplemented light-activated sensing array was demonstrated,opening up new avenues for advancements in light-activated electronic nose technologies.

关键词： Micro-LED Gas sensor array Low power consumption Metal decoration Real-time detection

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Two-dimensional magnetic materials for spintronic applications

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Nano Research 2024年第2期17卷 743-762页

作者： Shivam N.Kajale Jad Hanna Kyuho jang Deblina Sarkar MIT Media Lab Massachusetts Institute of TechnologyCambridgeMA 02139USA Department of Information Technology and Electrical Engineering ETH ZürichZürich8092Switzerland

Spintronic devices are driving new paradigms of bio-inspired,energy efficient computation like neuromorphic stochastic computing and in-memory *** have also emerged as key candidates for non-volatile memories for embedded systems as well as alternatives to persistent *** meet the growing demands from such diverse applications,there is need for innovation in materials and device designs which can be scaled and adapted according to the ***-dimensional(2D)magnetic materials address challenges facing bulk magnet systems by offering scalability while maintaining device integrity and allowing efficient control of *** this review,we highlight the progress made in experimental studies on 2D magnetic materials towards their integration into spintronic *** provide an account of the various relevant material discoveries,demonstrations of current and voltage-based control of magnetism and reported device systems,while also discussing the challenges and opportunities towards integration of 2D magnetic materials in commercial spintronic devices.

关键词： spintronics van der Waals magnetic tunnel junction(MTJ) spin-orbit torque magnetism

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