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New insights on thermal ageing of electrical insulating oils as revealed from photoluminescence and absorption spectroscopy

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High Voltage 2024年第5期9卷 1033-1045页

作者： Hesham S.Karaman Eman G.Atiya Diaa-Eldin A.Mansour Mohsen Ghali Z.M.S.Elbarbary Manal M.Emara Department of Electrical Engineering Faculty of Engineering at ShoubraBenha UniversityCairoEgypt Department of Electrical Power and Machines Engineering Faculty of EngineeringTanta UniversityTantaEgypt Department of Electrical Power Engineering Faculty of EngineeringEgypt-Japan University of Science and Technology(E-JUST)New Borg El-Arab CityAlexandriaEgypt Department of Energy Materials Institute of Basic and Applied ScienceEgypt-Japan University of Science and Technology(E-JUST)New Borg El-Arab CityAlexandriaEgypt Department of Physics Faculty of ScienceKafrelsheikh UniversityKafrelsheikhEgypt Department of Electrical Engineering College of EngineeringKing Khalid UniversityAbhaSaudi Arabia Center for Engineering and Technology Innovations King Khalid UniversityAbhaSaudi Arabia Department of Electrical Engineering Faculty of EngineeringKafrelsheikh UniversityKafrelsheikhEgypt

Recently,significant efforts have been exerted to replace mineral oil with environmentally friendly oils due to safety and environmental ***,there is a need to clarify the physical mechanisms behind the ageing impact of these *** authors use advanced optical spectroscopy techniques in correlation with dielectric measurements to understand the ageing processes in environmentally friendly oils as well as mineral ***,different samples of environmentally friendly oils and mineral oil were utilised to investigate the ageing *** samples were subjected to different ageing periods using a thermal accelerated ageing ***,the severity of the produced byproducts due to the oil degradation is examined based on several measured properties representing macroscopic and microscopic *** macroscopic category was evaluated through dielectric properties,including breakdown voltage,dielectric permittivity,and dissipation *** microscopic category,on the other hand,was assessed using techniques such as ultraviolet-visible absorption spectroscopy and photoluminescence *** techniques enabled a deep understanding of the molecular-level changes occurring in the oil under ageing conditions,thereby getting new insights into oil ageing *** is worth mentioning that natural ester oil demonstrated the most favourable performance across various properties under ageing conditions.

关键词： absorption thermal spectroscopy

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Axial coordinated iron-nitrogen-carbon as efficient electrocatalysts for hydrogen evolution and oxygen redox reactions

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Chinese Chemical Letters 2025年第1期36卷 637-642页

作者： Yanan Zhou Li Sheng Lanlan Chen Wenhua Zhang Jinlong Yang School of Material Science and Chemical Engineering Institute of Mass SpectrometryNingbo UniversityNingbo 315211China Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China Department of Material Science and Engineering University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory for Physical Sciences at the Microscale CAS Key Laboratory of Materials for Energy Conversion and Synergetic Innovation Centre of Quantum Information and Quantum PhysicsUniversity of Science and Technology of ChinaHefei 230026China

Designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy ***,based on density functional theory(DFT)calculations,we systematically investigate the catalytic activity of iron-nitrogen-carbon based covalent organic frameworks(COF)monolayers with axially coordinated ligands(denotes as Fe N_(4)-X@COF,X refers to axial ligand,X=-SCN,-I,-H,-SH,-NO_(2),-Br,-ClO,-Cl,-HCO_(3),-NO,-ClO_(2),-OH,-CN and-F).The calculated results demonstrate that all the catalysts possess good thermodynamic and electrochemical *** different ligands axially ligated to the Fe active center could induce changes in the charge of the Fe center,which further regulates the interaction strength between intermediates and catalysts that governs the catalytic ***,FeN_(4)-SH@COF and Fe N_(4)-OH@COF are efficient bifunctional catalysts for HER and OER,FeN_(4)-OH@COF and FeN_(4)-I@COF are promising bifunctional catalysts for OER and *** findings not only reveal promising bifunctional HER/OER and OER/ORR catalysts but also provide theoretical guidance for designing optimum ironnitrogen-carbon based catalysts.

关键词： Axial coordinated ligands DFT calculation Hydrogen evolution reaction Oxygen evolution reaction Oxygen reduction reaction

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Large Photoinduced Tuning of Ferroelectricity in Sliding Ferroelectrics

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Physical Review Letters 2024年第19期133卷 196801页

作者： Lingyuan Gao Laurent Bellaiche Smart Ferroic Materials Center Physics Department and Institute for Nanoscience and Engineering Department of Materials Science and Engineering

Stacking nonpolar, monolayer materials has emerged as an effective strategy to harvest ferroelectricity in two-dimensional (2D) van der Waals (vdW) materials. At a particular stacking sequence, interlayer charge transfer allows for the generation of out-of-plane dipole components, and the polarization magnitude and direction can be altered by an interlayer sliding. In this work, we use ab initio calculations and demonstrate that in prototype sliding ferroelectrics rhombohedrally-stacked bilayer transition metal dichalcogenides MoS2, the out-of-plane electric polarization can be robustly tuned by photoexcitation in a large range for a given sliding. Such tuning is associated with both a structural origin—i.e., photoinduced structural distortion—and a charge origin, namely, the distribution of photoexcited carriers. We elucidate different roles that photoexcitation plays in modulating sliding ferroelectricity under different light intensities, and we highlight the pivotal role of light in manipulating polarization of 2D vdW materials.

关键词： Electric polarization Ferroelectricity Light-matter interaction Photoinduced effect Two-dimensional electron system Density functional calculations

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Precipitation and coarsening kinetics of H-phase in NiTiHf high temperature shape memory alloy

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Journal of materials science & Technology 2022年第19期114卷 90-101页

作者： A.Shuitcev Y.Ren B.Sun G.V.Markova L.Li Y.X.Tong Y.F.Zheng Institute of Materials Processing and Intelligent Manufacturing College of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China Center of Testing and Analysis College of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China Physics of Metal and Material Science Department Tula State UniversityTula 300012Russian Federation School of Materials Science and Engineering Peking UniversityBeijing 100871China

Precipitate hardening is the most easiest and effective way to enhance strain recovery properties in NiTiHf high-temperature shape memory *** paper discusses the precipitation,coarsening and age hardening of H-phase precipitates in Ni_(50)Ti_(30)Hf_(20)alloy during isothermal aging at temperatures between 450℃and 650℃for time to 75 *** H-phase mean size and volume fraction were determined using transmission electron *** kinetics was analyzed using the Johnson-Mehl-Avrami-Kolmogorov equation and an Arrhenius type *** these analyses,a Time-Temperature-Transformation diagram was *** evolution of H-phase size suggests classical matrix diffusion limited Lifshitz-Slyozov-Wagner coarsening for all considered *** coarsening rate constants of H-phase precipitation have been determined using a modified coarsening rate equation for nondilute *** size of H-phase precipitates for breaking down the precipitate/matrix interface coherency was estimated through a combination of age hardening and precipitate size evolution ***,time-temperature-hardness diagram was constructed from the precipitation and coarsening kinetics and age hardening of H-phase precipitates in Ni_(50)Ti_(30)Hf_(20)alloy.

关键词： High temperature shape memory alloys NiTiHf Time-temperature-transformation diagram Coarsening kinetics H-phase

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Cyclic-anion salt for high-voltage stable potassium-metal batteries

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National science Review 2022年第10期9卷 177-187页

作者： Yanyao Hu Ling Fan Apparao M.Rao Weijian Yu Caixiang Zhuoma Yanhong Feng Zhihui Qin Jiang Zhou Bingan Lu School of Physics and Electronics Hunan University Department of Physics and Astronomy Clemson Nanomaterials Institute Clemson University School of Materials Science and Engineering Central South University

Electrolyte anions are critical for achieving high-voltage stable potassium-metal batteries(PMBs).However,the common anions cannot simultaneously prevent the formation of 'dead K' and the corrosion of Al current collector,resulting in poor cycling ***,we demonstrate cyclic anion of hexafluoropropane-1,3-disulfonimide-based electrolytes that can mitigate the 'dead K' and remarkably enhance the high-voltage stability of ***,even using low salt concentration(0.8 M) and additive-free carbonate-based electrolytes,the PMBs with a high-voltage polyanion cathode(4.4 V) also exhibit excellent cycling stability of 200 cycles with a good capacity retention of 83%.This noticeable electrochemical performance is due to the highly efficient passivation ability of the cyclic anions on both anode and cathode *** cyclic-anion-based electrolyte design strategy is also suitable for lithium and sodium-metal battery technologies.

关键词： cyclic anion low concentration additive-free electrolyte high-voltage potassium-metal batteries solid–electrolyte interface

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Polyetheretherketone (PEEK) Implant Functionalization with Magnetron-Sputtered SrTiO3 for Regenerative Medicine

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Plasma Medicine 2023年第3期13卷 53-67页

作者： Harumningtyas, Anjar Anggraini Ito, Tomoko Ikuta, Masato Kaito, Takashi Hamaguchi, Satoshi International Priority Graduate Program on Applied and Engineering Physics Division of Precision Engineering and Applied Physics Osaka University Osaka Japan Yogyakarta Indonesia Division of Materials and Manufacturing Science Graduate School of Engineering Osaka University Osaka Japan Department of Orthopaedic Surgery Osaka University Graduate School of Medicine Osaka Japan

Polyetheretherketone (PEEK) is a polymer widely used for artificial bone implants but exhibits a low affinity for bone tissue and lacks osteoconductivity and osseointegration. Because strontium (Sr) is known to enhance bone growth, PEEK implants coated with strontium titanate [SrTiO3 (STO)] are expected to improve the bone growth around them. In this study, STO was deposited on model PEEK implants by magnetron sputtering deposition and its ability to release Sr2+ ions to a surrounding phosphate-buffered saline (PBS) solution was examined. It was found that, in the early stage of the deposition process, STO on a PEEK surface exhibits irregular surface structures with many holes. The amount of Sr stored in the STO film increases with the increasing film thickness but the release rate of Sr2+ ions from the STO film to the surrounding PBS also increases with the film thickness, limiting the duration of effectiveness of the STO-coated PEEK films. It was found, however, that a three-layer titanium (Ti)-STO-Ti film deposited on PEEK allows a steady release of Sr2+ ions to the surrounding PBS for an extended period. © 2023 by Begell House, Inc. ***.

关键词： Titanium compounds

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Effect of Plasma Treatment on Ice Plant Germination and Physicochemical Surface Using Dielectric Barrier Discharge

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IEEE Transactions on Plasma science 2023年第2期51卷 444-450页

作者： Chen, Tzu-Ling Lai, Yuan-Tai Hsu, Sheng-Yu Chang, Shou-Yi Hung, Hsueh-Hsing Duh, Jenq-Gong National Tsing-Hua University Department of Materials Science and Engineering Hsinchu30013 Taiwan National Tsing-Hua University Department of Physics Hsinchu30013 Taiwan

Atmospheric pressure plasma treatment on seeds has recently become a valuable technique to improve germination. This work treated Mesembryanthemum crystallinum (ice plant) seeds by the dielectric barrier discharge (DBD) atmospheric pressure plasma at room temperature. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) indicate that after plasma treatment, the N-H stretching vibration of proteins ( \sim 3340 cm ^{-1} ) is introduced into the seed surface, increasing the nitrogen content on the surface of the ice plant. Therefore, the seed germination rate increased significantly by 15.2%. However, prolonged plasma treatment reduces seed germination. Because the operating surrounding temperature increases with the treatment time, the wax on the surface of the seed is evaporated, resulting in a significant increase water uptake of seeds. Excess water uptake hinders oxygen diffusion to the embryo, affecting germination. A feasible mechanism and effects of plasma treatment on ice plants are proposed in this study. DBD plasma-treated ice plants significantly increase germination rates, showing excellent potential in the agricultural field. © 1973-2012 IEEE.

关键词： Dielectric devices

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Electric-field-induced controlled motion of polar meron in epitaxially strained BiFeO3 thin film

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Physical Review materials 2024年第10期8卷 104406页

作者： Sukriti Mantri Sergei Prokhorenko Yousra Nahas Laurent Bellaiche Smart Ferroic Materials Center Physics Department and Institute for Nanoscience and Engineering Department of Materials Science and Engineering

Using first principles–based effective Hamiltonian, electric field–controlled (reversible and repeatable) motion of spontaneously created topological charge particle across the thickness of a (001)-oriented epitaxially strained BiFeO3 thin film is studied. It is shown that the electric field below a critical value moves this topological particle reversibly and gradually up and down across the film thickness, while the field higher than the critical value moves it from the bottom of the thin film straight to the top and back under alternating positive and negative fields. These field-controlled mobile topological charge particles are shown to be chiral and have topological charge corresponding to a meron. These electric-field-controlled meron motions can provide inspiration for the future of topological entity–based ferroelectric memory devices.

关键词： Defects Electric polarization Ferroelectricity Topological materials Vortex interactions Multiferroics Thin films Monte Carlo methods

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Dynamics of Polar Vortex Crystallization

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Physical Review Letters 2024年第9期133卷 096801页

作者： S. Rijal Y. Nahas S. Prokhorenko L. Bellaiche Smart Ferroic Materials Center Physics Department and Institute for Nanoscience and Engineering Department of Materials Science and Engineering

Vortex crystals are commonly observed in ultrathin ferroelectrics. However, a clear physical picture of origin of this topological state is currently lacking. Here, we show that vortex crystallization in ultrathin Pb(Zr0.4,Ti0.6)O3 films stems from the softening of a phonon mode and can be described as a Z2×SU(1) symmetry-breaking transition. This result sheds light on the topology of the polar vortex patterns and bridges polar vortices with smectic phases, spin spirals, and other modulated states. Finally, we predict a resonant switching of the vortex tube orientation driven by midinfrared laser light which could enable new technologies.

关键词： Electric polarization Ferroelectric domains Ferroelectricity Order parameters Phase transitions Phonons Topological materials Ultrathin films Molecular dynamics

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Designing artificial ion channels with strict K+/Na+ selectivity toward next-generation electric-eel-mimetic ionic power generation

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National science Review 2023年第12期10卷 193-202页

作者： Jipeng Li Linhan Du Xian Kong Jianzhong Wu Diannan Lu Lei Jiang Wei Guo State Key Laboratory of Marine Resource Utilization in South China Sea School of Materials Science and Engineering Hainan University Department of Chemical Engineering Tsinghua University South China Advanced Institute for Soft Matter Science and Technology Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices School of Emergent Soft MatterSouth China University of Technology Department of Chemical and Environmental Engineering University of California Research Institute for Frontier Science Beihang University Center for Quantum Physics and Intelligent Sciences Department of Physics Capital Normal University

A biological potassium channel is> 1000 times more permeable to K+than to Na+and exhibits a giant permeation rate of ～10～8 ions/*** is a great challenge to construct artificial potassium channels with such high sele ctivity and ion conduction ***,we unveil a long-overlo oked structural feature that underpins the ultra-high K+/Na+*** carrying out massive molecular dynamics simulation for ion transport through carbonyl-oxygen-modified bi-layer graphene nanopores,we find that the twisted carbonyl rings enable strict potassium selectivity with a dynamic K+/Na+selectivity ratio of 1295 and a K+conduction rate of 3.5 × 10～7 ions/s,approaching those of the biological ***,atomic trajectories of K+permeation events suggest a dual-ion transport mode,*** like-charged potassium ions are successively captured by the nanopores in the graphene bi-layer and are interconnected by sharing one or two interlayer water *** dual-ion behavior allows rapid release of the exiting potassium ion via a soft knock-on mechanism,which has previously been found only in biological ion *** a proof-of-concept utilization of this discovery,we propose a novel way for ionic power generation by mixing KCl and NaCl solutions through the bi-layer graphene nanopores,termed potassium-permselectivity enabled osmotic power generation（PoPee-OP G）.Theoretically,the biomimetic device achieves a very high power density of> 1000 W/m2with graphene sheets of <1% *** study provides a blueprint for artificial potassium channels and thus paves the way toward next-generation electric-eel-mimetic ionic power generation.

关键词： artificial ion channel bi-layer graphene dehydrated ion transport bio-inspired materials energy conversion

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