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Low-Velocity-Favored Transition Radiation

Physical Review Letters 2023年第11期131卷 113002-113002页

作者： Jialin Chen Ruoxi Chen Fuyang Tay Zheng Gong Hao Hu Yi Yang Xinyan Zhang Chan Wang Ido Kaminer Hongsheng Chen Baile Zhang Xiao Lin Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center College of Information Science & Electronic Engineering Zhejiang University Hangzhou 310027 China International Joint Innovation Center the Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Department of Electrical and Computer Engineering Technion-Israel Institute of Technology Haifa 32000 Israel Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas 77005 USA School of Electrical and Electronic Engineering Nanyang Technological University Singapore 639798 Singapore Department of Physics University of Hong Kong Hong Kong 999077 China Key Lab of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua 321099 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing 312000 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore Centre for Disruptive Photonic Technologies Nanyang Technological University Singapore 637371 Singapore

When a charged particle penetrates through an optical interface, photon emissions emerge—a phenomenon known as transition radiation. Being paramount to fundamental physics, transition radiation has enabled many applications from high-energy particle identification to novel light sources. A rule of thumb in transition radiation is that the radiation intensity generally decreases with the decrease of particle velocity v; as a result, low-energy particles are not favored in practice. Here, we find that there exist situations where transition radiation from particles with extremely low velocities (e.g., v/c<10−3) exhibits comparable intensity as that from high-energy particles (e.g., v/c=0.999), where c is the light speed in free space. The comparable radiation intensity implies an extremely high photon extraction efficiency from low-energy particles, up to 8 orders of magnitude larger than that from high-energy particles. This exotic phenomenon of low-velocity-favored transition radiation originates from the interference of the excited Ferrell-Berreman modes in an ultrathin epsilon-near-zero slab. Our findings may provide a promising route toward the design of integrated light sources based on low-energy electrons and specialized detectors for beyond-standard-model particles.

关键词： Atom or molecule scattering from surfaces Atomic & molecular collisions Cherenkov radiation Crystal optics Electron beams & optics Light-matter interaction Optical sources & detectors Optical transient phenomena Plasmonics

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Molecular engineering of Azobenzene-Based Anolytes Towards High-Capacity Aqueous Redox Flow Batteries

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Advanced Materials 2020年第49期132卷 22347-22354页

作者： Zu, Xihong Zhang, Leyuan Qian, Yumin Zhang, Changkun Yu, Guihua Materials Science and Engineering Program and Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States School of Chemical Engineering and Light Industry Guangdong University of Technology Guangdong Guangzhou510006 China

Aqueous redox flow batteries (RFBs) are promising alternatives for large-scale energy storage. However, new organic redox-active molecules with good chemical stability and high solubility are still desired for high-performance aqueous RFBs due to their low crossover capability and high abundance. We report azobenzene-based molecules with hydrophilic groups as new active materials for aqueous RFBs by utilizing the reversible redox activity of azo groups. By rationally tailoring the molecular structure of azobenzene, the solubility is favorably improved from near zero to 2 M due to the highly charged asymmetric structure formed in alkaline environment. DFT simulations suggest that the concentrated solution stability can be enhanced by adding hydrotropic agent to form intermolecular hydrogen bonds. The demonstrated RFB exhibits long cycling stability with a capacity retention of 99.95% per cycle over 500 cycles. It presents a viable chemical design route towards advanced aqueous RFBs. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

关键词： Hydrogen bonds

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On-chip unidirectional waveguiding for surface acoustic waves along a defect line in a triangular lattice

arXiv

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arXiv 2021年

作者： Zhou, Yun Zhang, Naiqing Bisharat, Diaaaldin J. Davis, Robert J. Zhang, Zichen Friend, James Bandaru, Prabhakar R. Sievenpiper, Daniel F. Department of Mechanical Engineering University of California San Diego La Jolla CA92093-0411 United States Department of Electrical Engineering University of California San Diego La Jolla CA92093-0411 United States Program in Materials Science University of California San Diego La Jolla CA92093-0411 United States

The latest advances in topological physics have yielded a rich toolset to design highly robust wave transfer systems, for overcoming issues like beam steering and lateral diffraction in surface acoustic waves (SAWs). However, presently used designs for topologically protected SAWs have been largely limited to spin or valley-polarized phases, which rely on non-zero Berry curvature effects. Here we propose and experimentally demonstrate a highly robust SAW waveguide on lithium niobate (LiNbO3), based on a line defect within a true triangular phononic lattice, which instead employs an intrinsic chirality of phase vortices and maintains a zero Berry curvature. The guided SAW mode spans a wide bandwidth (Equation presented) and shows confinement in the lateral direction with 3 dB attenuation within half of the unit-cell length. SAW routing around sharp bends has been demonstrated in such waveguide, with less than ~4% reflection per bend. The waveguide has also been found robust for defect lines with different configurations. The fully on-chip system permits unidirectional SAW modes that are tightly bound to the waveguide, which provides a compact footprint ideal for miniaturization of practical applications and offers insight into the possibility of manipulating highly focused SAW propagation. Copyright © 2021, The Authors. All rights reserved.

关键词： Acoustic waves

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Fabrication of PDMS-Stabilized porous silver films derived from recovered silver sources as flexible conductive materials

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Journal of Industrial and engineering Chemistry 2025年

作者： Natsuda Muankhajorn Sanong Ekgasit Akira Baba Wisansaya Jaikeandee Porapak Suriya Taveesak Janduang Kanet Wongravee Sensor Research Unit (SRU) Department of Chemistry Faculty of Science Chulalongkorn University Bangkok 10330 Thailand Program in Petrochemistry and Polymer Science Faculty of Science Chulalongkorn University Pathumwan Bangkok 10330 Thailand Graduate School of Science and Technology and Faculty of Engineering Niigata University 8050 Ikarashi 2-nocho Nishi-ku Niigata 950-2181 Japan Public Administration Faculty of Science Chulalongkorn University Pathumwan Bangkok 10330 Thailand

This study presents a straightforward and efficient approach for the fabricating flexible conductive materials by integrating porous silver films onto a PDMS substrate. The process involves oxidative acetoxylation of silver into silver acetate (AcOAg) using ethyl acetate, followed by thermal decomposition to generate a porous silver structure on the PDMS suitable for flexible electronics. The impact of different silver sources including pure silver beads and recovered silver microstructures (irregular sphere and plate-like shape from spent button batteries) on acetoxylation process was investigated. Regardless of the initial silver morphology, rod-shaped silver acetate (RS-AcOAg) formed consistently, demonstrating the silver acetoxylation reaction independence from the silver source. Upon thermal decomposition, RS-AcOAg transformed into porous silver films, but uncontrolled sintering resulted in rigid structures that degraded electrical properties. To improve conductive activities, the introduction of PDMS as a surface stabilizing agent effectively suppressed sintering, preserving porous structure. Electrical characterization revealed that non-PDMS-coated silver strips exhibited high relative resistance change (Δ R / R 0 ) values with irreversible behavior due to internal cracking, whereas PDMS-coated porous silver films demonstrate lower Δ R/R 0 values with excellent reversibility under mechanical strain (stretching and bending). These findings confirm that PDMS-stabilized porous silver films offer a promising route for flexible conductive materials, with enhanced structural integrity and mechanical durability.

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Asymmetric response of the Western North Pacific tropical cyclone genesis to symmetric CO2 pathway

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npj Climate and Atmospheric science 2025年第1期8卷 1-15页

作者： Hyunsuk Yoon Seok-Woo Son Jong-Seong Kug Jaeyeon Lee Hyeong-Seog Kim Chao Liu Soon-Il An Seung-Ki Min Sang-Wook Yeh School of Earth and Environmental Sciences Seoul National University Seoul South Korea Interdisciplinary Program in Artificial Intelligence Seoul National University Seoul South Korea Atmospheric and Oceanic Sciences Program Princeton University Princeton NJ USA Ocean Science and Technology School Korea Maritime and Ocean University Busan South Korea Department of Atmospheric Sciences Yonsei University Seoul South Korea Division of Environmental Science and Engineering Pohang University of Science and Technology (POSTECH) Pohang South Korea Institute for Convergence Research and Education in Advanced Technology Yonsei University Seoul South Korea Department of Marine Science and Convergence Engineering Hanyang University Ansan South Korea

The responses of the western North Pacific (WNP) tropical cyclone (TC) genesis and associated large-scale atmospheric environment to varying CO2pathways are investigated using an idealized CO2removal experiment. In the experiment, CO2concentration is first increased at the rate of 1% year−1until quadrupled and then decreased at the same rate until it reaches the initial level. Our results indicate asymmetric changes in WNP peak-season (July–September) TC genesis between CO2ramp-up and ramp-down periods, showing a significant reduction of TC genesis over the Philippine Sea and landfalling TCs in East Asia when the CO2concentration is reduced. Such TC activity changes are attributed to the development of WNP anticyclonic circulation in the ramp-down period, in association with an El Niño-like delayed response in sea surface temperature. This asymmetric response of WNP TC activities to symmetric CO2pathway may provide a reference for regional TC disaster prevention and preparations under mitigation conditions.

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Impact of mining on land use land cover change and water quality in the Asutifi North District of Ghana, West Africa

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Environmental Challenges 2022年 6卷

作者： Gbedzi, Divine Dodzi Ofosu, Eric Antwi Mortey, Eric Mensah Obiri-Yeboah, Abena Nyantakyi, Emmanuel Kwesi Siabi, Ebenezer Kwadwo Abdallah, Faisal Domfeh, Martin Kyereh Amankwah-Minkah, Anna Department of Civil and Environmental Engineering University of Energy and Natural Resources Sunyani Ghana Earth Observation Research and Innovation Centre (EORIC) University of Energy and Natural Resources Sunyani Ghana Department of Civil Engineering Kumasi Technical University Kumasi 00233 Ghana Faculty of Science and Techniques Doctoral Research Program in Climate Change and Energy (DRP-CCE) of the West African Science Service Center on Climate Change and Adapted Land Use (WASCAL) Université Abdou Moumouni P.O. Box 10662 Niamey 8000 Niger

Surface and groundwater are important resources for human life and health. Land use changes and mining activities, however, have the potential to compromise the safety of these resources. This study aims to investigate the land cover conditions before and during mining activities and assess the impact on forests, surface, and groundwater resources in the Asutifi North District, Ghana. Landsat data of 30 m resolution was used to assess the land cover change from 2000 to 2020. A cross-sectional analysis of data between April to June 2004 to 2019 was used to assess water quality. The overall accuracy of the land cover classification ranged between (91.33–99.41)% and (78.01–85.95)% respectively for ground-truth validation and validation using the MODIS annual 500 m land cover dataset. Forest cover decreased by 11.47% while agriculture doubled from 12.13% to 24.06% between 2000 and 2020. The introduction of mining is responsible for major land cover changes including the conversion of forest to agricultural land through shifting cultivation. For a general assessment of water quality, the percentage of pH, TB, TDS, NH₃, Mg and SO₄ measurements outside the EPA admissible limits for drinking water is 16.67%, 83.33%, 0.69%, 0%, 10.42%, and 16.67% respectively. Turbidity is the most impacted water quality parameter affected by land cover changes while NH₃ is the least impacted parameter. The incidences of water quality outside EPA/WHO limits for drinking water at all monitoring points call for education and collective action to safeguard water sources from further deterioration. It is necessary mining companies adhere to environmental protection guidelines. © 2022

关键词： Groundwater Illegal mining Land use land cover change Surface water Sustainable Development Goals (SDGs)

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In-Situ Determination of Moisture- and Temperature-Driven Deflection of an Encapsulated Si Photovoltaic Cell

SSRN

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SSRN 2022年

作者： Slauch, Ian M. Gandhi, Hir Kumar, Rishi E. Sidawi, Tala Tracy, Jared Choudhury, Roy Kaushik Meier, Rico Fenning, David P. Bertoni, Mariana I. Arizona State University Fulton School of Engineering 650 E Tyler Mall TempeAZ United States University of California San Diego Materials Science Program La Jolla CA United States University of California San Diego Department of Nanoengineering La Jolla CA United States DuPont Photovoltaic and Advanced Materials WilmingtonDE United States

Module reliability and service lifetime are critical factors in improving photovoltaic system performance and reducing the levelized cost of electricity (LCOE). Soldering and lamination of the cell impart residual stresses that persist over time and superimpose additional loads during operation. This paper demonstrates the use of X-ray Topography (XRT) to image in-situ the dynamic response of a glass/backsheet mini-module upon drying at elevated temperature after saturation at humidity levels used in accelerated testing. The local water content in the encapsulant is also determined in-situ over time via Water Reflectometric Detection (WaRD), with diffusion of water in the front (glass side) and rear (backsheet side) resolved. As water diffuses out from the back of the glass/backsheet module, the cell curves towards the backsheet concomitantly. The local cell deflections (changes in cell orientation) are correlated with the dynamic loss of water in the backside encapsulant. We conclude that the observed cell deflections are the result of hygroscopic stress induced by the encapsulant upon moisture outdiffusion. Therefore, the cell experiences a continually changing stress state and curvature dependent on local humidity and temperature. Depending on cell architecture and interconnection, this "breathing" mode of the cell may affect the disconnection of cracked pieces or cause wear out and fatigue of the interconnects, especially as elevated operating temperature allows a greater amount of water into the encapsulant. © 2022, The Authors. All rights reserved.

关键词： Glass

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Hybrid Vesicles Enable Mechano-Responsive Hydrogel Degradation

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Angewandte Chemie 2023年第41期135卷

作者： Sung-Won Hwang Chung-Man Lim Prof. Cong Truc Huynh Hossein Moghimianavval Prof. Nicholas A. Kotov Prof. Eben Alsberg Prof. Allen P. Liu Department of Chemical Engineering University of Michigan Ann Arbor MI 48109 USA Department of Materials Science and Engineering University of Michigan Ann Arbor MI 48109 USA Department of Biomedical Engineering University of Illinois Chicago Chicago IL 60612 USA Department of Mechanical Engineering University of Michigan Ann Arbor MI 48109 USA Departments of Biomedical Engineering Macromolecular Science and Engineering Biointerfaces Institute University of Michigan Ann Arbor MI 48109 USA Departments of Orthopedic Surgery Pharmacology and Regenerative Medicine and Mechanical and Industrial Engineering University of Illinois Chicago Chicago IL 60612 USA Departments of Biomedical Engineering Biophysics Cellular and Molecular Biology Program Applied Physics Program University of Michigan Ann Arbor MI 48109 USA

Stimuli-responsive hydrogels are intriguing biomimetic materials. Previous efforts to develop mechano-responsive hydrogels have mostly relied on chemical modifications of the hydrogel structures. Here, we present a simple, generalizable strategy that confers mechano-responsive behavior on hydrogels. Our approach involves embedding hybrid vesicles, composed of phospholipids and amphiphilic block copolymers, within the hydrogel matrix to act as signal transducers. Under mechanical stress, these vesicles undergo deformation and rupture, releasing encapsulated compounds that can control the hydrogel network. To demonstrate this concept, we embedded vesicles containing ethylene glycol tetraacetic acid (EGTA), a calcium chelator, into a calcium-crosslinked alginate hydrogel. When compressed, the released EGTA sequesters calcium ions and degrades the hydrogel. This study provides a novel method for engineering mechano-responsive hydrogels that may be useful in various biomedical applications.

关键词： Block Copolymers Functional Material Stimuli-Responsive Hydrogel Stress-Induced Degradation Vesicles

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Deactivation/Regeneration Studies in Structured Monolithic Ni-Based Catalysts Applied in Dry Reforming of Methane

SSRN

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SSRN 2022年

作者： de Araújo, Ítalo R.S. Ribeiro, André T.S. Garcia, Ramón R.P. Sales, Deivson C.S. Almeida, Luciano C. Department of Chemical Engineering Technology and Geoscience Center Federal University of Pernambuco PE Recife50740-521 Brazil Polytechnic School of Pernambuco University of Pernambuco Rua Benfica 455 Madalena PE Recife50720-001 Brazil Materials Science and Engineering Graduate Program Federal University of Piauí PI Teresina Brazil Federal Rural University of Pernambuco Academic Unit of Cabo de Santo Agostinho PE Cabo de Santo Agostinho Brazil

In this work, the Ni/γ-Al2O3 (Ni/Al) and Ni/LA2O3-γ-Al2O3 (Ni/La-Al) catalysts were synthesized by the all-in-one method and used in the Dry Reforming of Methane (DRM). The catalysts were characterized and a smaller Ni crystallite size for the La-promoted catalyst was observed. The effects of the feed ratio (CH4:CO2), the use of La as a promoter of the catalyst support, and the use of the structured system in DRM reaction were investigated. Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were applied to investigate the catalytic deactivation effects. The deactivation of the structured catalysts was also evaluated by applying different weight hourly space velocities (WHSV): 20, 30, and 40 L gcat-1 h-1. Besides that, the regeneration of the catalysts was developed through the comparison of the treatment with CO2 and H2 atmospheres. The catalytic study of the powder samples showed that the lower the CH4:CO2 ratio the higher reactants conversion for both catalysts. It was also noted that the CH4:CO2 feed ratio of 4 provided a conversion 10 % higher for the Ni/La-Al catalyst in comparison with the Ni/Al catalyst. The analogy between the powder and structured systems implied greater conversion for the structured system. Furthermore, the greater and the lower deactivation of the structured systems were identified for the WHSV values of 40 and 20 L gcat-1 h-1, respectively. Finally, the regeneration treatment with CO2 showed to be more efficient than the treatment with H2 © 2022, The Authors. All rights reserved.

关键词： Carbon dioxide

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Research on matching accuracy of underwater terrain matching algorithm based on unscented kalman filter 2019

Research on matching accuracy of underwater terrain matching...

引用

4th International Conference on Mathematics and Artificial Intelligence, ICMAI 2019

作者： Lu, Xiong Jian, Shen Xiaowen, Bi Department of Radar System OrdnanceNCO. Academy Army engineering university Wuhan China Post-doctoral program on control science and engineering Naval University of Engineering Wuhan China

ISBN: (纸本)9781450362580

UT transform is the core step of unscented kalman filter (UKF) algorithm. The Sigma sampling type of UT transform has great influence on the computational complexity, state estimation accuracy and computational efficiency of UKF-based terrain matching algorithm. In order to obtain the high precision terrain matching method which is suitable for engineering application, the Comparative analysis of three kinds of UKF-based terrain matching algorithms was carried out in this paper. Firstly, the UKF-based underwater terrain matching model was given. Secondly, the principle and the performance characteristics of scaled sampling method, Cubature sampling method, Gauss- Hermite sampling methods were analyzed. The filtering precision factors of symmetric unscented Kalman filter(SUKF), Cubature unscented Kalman filter(CKF), Gauss-Hermite Kalman Filter(GHKF) was studied from the algorithm principle, Thirdly, The computer simulation was performed using univariate nonstationary growth model(UNGM) to test the previous analysis conclusions. Finally underwater terrain matching simulation model was established, and the comparative analysis of matching acuraccy was carried out based on SITAN, SUKF, CKF and GHKF, the matching effect of underwater terrain matching algorithm is obtained. The simulation results show that the UKF algorithm based on symmetric sampling strategy has better filtering precision and less computational complexity which is suitable for the filtering core of underwater terrain matching algorithm. © 2019 Association for Computing Machinery.

关键词： Kalman filters

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