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Chiral exceptional point enhanced active tuning and non reciprocity in micro-resonators

光：科学与应用（英文版） 2025年第2期14卷 401-410页

作者： Hwaseob Lee Lorry Chang Ali Kecebas Dun Mao Yahui Xiao Tiantian Li Andrea Alù Sahin K.Özdemir Tingyi Gu Department of Electrical and Computer Engineering University of DelawareNewarkDelaware 19716USA Department of Engineering Science and Mechanics Pennsylvania State UniversityUniversity ParkPA 16802USA Photonics Initiative Advanced Science Research CenterCity University of New YorkNew YorkNY 10031USA Physics Program Graduate CenterCity University of New YorkNew YorkNY 10016USA Department of Engineering Science and Mechanics Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Electrical and Computer Engineering Saint Louis UniversitySaint LouisMO 63103USA

Exceptional points(EPs)have been extensively explored in mechanical,acoustic,plasmonic,and photonic ***,little is known about the role of EPs in tailoring the dynamic tunability of optical devices.A specific type of EPs known as chiral EPs has recently attracted much attention for controlling the flow of light and for building sensors with better responsivity.A recently demonstrated route to chiral EPs via lithographically defined symmetric Mie scatterers on the rim of resonators has not only provided the much-needed mechanical stability for studying chiral EPs,but also helped reduce losses originating from nanofabrication imperfections,facilitating the in-situ study of chiral EPs and their contribution to the dynamics and tunability of ***,we use asymmetric Mie scatterers to break the rotational symmetry of a microresonator,to demonstrate deterministic thermal tuning across a chiral EP,and to demonstrate EP-mediated chiral optical nonlinear response and efficient electro-optic *** results indicate asymmetric electro-optic modulation with up to 17 dB contrast at GHz and CMOS-compatible voltage *** wafer-scale nano-manufacturing of chiral electro-optic modulators and the chiral EP-tailored tunning may facilitate new micro-resonator functionalities in quantum information processing,electromagnetic wave control,and optical interconnects.

关键词： active point micro chiral enhanced exceptional reciprocity resonators tuning

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Analysis of Partial Discharges in Oil-Impregnated Transformer Paper Insulation and PET-G Insulation

IEEE Open Journal of Instrumentation and Measurement

引用

IEEE Open Journal of Instrumentation and Measurement 2025年 4卷

作者： Kameli, Sayed Mohammad Abuelrub, Abdelaziz AlShaikh Saleh, Mohammad Refaat, Shady S. Ghrayeb, Ali Abu-Rub, Haitham Olesz, Marek Texas A&M University at Qatar Electrical and Computer Engineering Department Doha Qatar Texas A&M University Department of Electrical and Computer Engineering College StationTX77843 United States University of Hertfordshire School of Physics Engineering and Computer Science Department of Engineering HatfieldAL10 9EU United Kingdom Hamad Bin Khalifa University Qatar Foundation Electrical and Computer Engineering Program in College of Science and Engineering Doha Qatar Gdańsk University of Technology Department of Electrical Power Engineering Gdańsk80-233 Poland

Partial discharge (PD) is a widespread phenomenon instigated in power transformer (PT) insulation systems. PDs are triggered by voids that vary in size and position within the PT insulation. The electrical characteristics of those damaging, PD-causing cavities must be well understood, to accelerate the development of advanced PD detection techniques. Thus, the impact of varying the radius and position of spherical air voids on the characteristics of PDs in PTs is examined using a 3-D finite element analysis (FEA) model designed in COMSOL Multiphysics. The spherical voids are positioned between two windings of a 512 kV, three-phase (3φ ) PT. The peak electric field (EF) and aggregate energy in the FEA model are used in conjunction with laboratory measurements of the apparent discharge magnitude, for detailed analysis of Polyethylene Terephthalate Glycol (PET-G)-based cylindrical voids with different heights. Simulations demonstrate that the inception of PD activity in the PT model occurs for spherical voids with a radius exceeding 1 mm. Furthermore, the most severe PDs occur within the press-board insulation, adjacent to the uppermost part of the innermost windings. Experiments demonstrate that a significant increase in PD activity was observed for PET-G-based cylindrical voids with heights exceeding 1 mm. © 2022 IEEE.

关键词： Partial discharges

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Development of Flexible Sendust Composite Sheets with Enhanced Magnetic Permeability for Microwave Absorbers and Antennas

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IEEE Transactions on Magnetics 2025年

作者： Whalen, Matthew P. Plouff, David T. Shevchenko, Nicholas B. Mirotznik, Mark Xiao, John Q. University of Delaware Quantum Science and Engineering Program NewarkDE19716 United States University of Delaware Department of Physics and Astronomy NewarkDE19716 United States University of Delaware Center for Composite Materials NewarkDE19716 United States University of Delaware Department of Electrical and Computer Engineering NewarkDE19716 United States

The demand for high-frequency soft magnetic composites with elevated permeability and flexibility is growing for applications in microwave absorbers and magnetodielectric antennas. However, balancing high permeability with mechanical flexibility remains challenging. This study presents flexible Sendust (FeSiAl) composite sheets, fabricated with a hot-pressing technique that aligns flakes within an acrylic rubber and epoxy resin matrix. The alignment significantly enhances relative permeability at high frequencies, achieving single-layer film properties of μr' = 14.8 and μr"= 20.4 at 1 GHz, alongside high saturation magnetization (118 eμg) and high hesitivity (44.7 kΩ m-1), outperforming commonly used materials such as NiZn ferrite. Our method supports customizable thickness without sacrificing permeability, establishing a versatile platform for advanced conformal microwave absorber and antenna applications. © 2025 IEEE.

关键词： Saturation magnetization

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Evaluation of Maternal and Fetal S-Values from Iodine Isotopes in Nuclear Medicine Using the Monte Carlo Method

SSRN

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SSRN 2025年

作者： Coelho, Nathalia B.M. Alves, Arthur de Souza Borges Zuchet Santos, Carla J. Neves, Lúcio P. Perini, Ana P. Belinato, Walmir Ferreira, José Rafael S. Santos, William S. Postgraduate Program in Biomedical Engineering Faculty of Electrical Engineering Federal University of Uberlândia Uberlândia Brazil Institute of Physics Federal University of Uberlândia Uberlândia Brazil Federal Institute of Bahia - IFBA BA Vitória da Conquista Brazil Department of Physics Federal University of Sergipe São Cristóvão Brazil Universidade Federal da Bahia Brazil

The use of radionuclides for therapeutic and diagnostic purposes is the primary function of nuclear medicine. Among these radionuclides, the iodine family stands out as isotopes that can serve various purposes, including brachytherapy, scintigraphy, and research. The internal dosimetry of these nuclides becomes even more important when considering high-risk groups such as pregnant patients, as it involves concerns for both the mother and the fetus. This study aims to use Monte Carlo simulations to calculate S-values for a set of target organs in both the pregnant woman and the fetus, considering different source organs in the mother and three iodine isotopes: 131I, 125I, and 123I. The results indicated that 131I, with the highest emission energy, presented a high dose deposition pattern in target organs farther from the source organs, while 125I, with the lowest energy, showed a localized dose absorption pattern in adjacent organs. The highest S-values (all in mGy/MBq.s) were obtained for the pregnant woman, with values of 5.8E-05 in the thyroid using 123I and 125I, and 3.7E-04 in the bladder using 131I. For fetal organs, the most irradiated were the brain and skull using 131I, with values of 6.3E-06 and 5.6E-06, respectively, while the lowest values were associated with the use of 125I in source organs distant from the target organ, with contributions as low as 1E-12 for the thyroid as a source. This work presents a qualitative and quantitative study of the internal dosimetry of a pregnant patient and her fetus, addressing variables such as radioactive isotope and source and target organs, serving as a reference for dosimetric calculations deemed necessary in clinical practices to minimize the dose received by this critical group. © 2025, The Authors. All rights reserved.

关键词： Nuclear medicine

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Topological wave phenomena in photonic time quasicrystals

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Physical Review B 2025年第12期111卷 125421-125421页

作者： Xiang Ni Shixiong Yin Huanan Li Andrea Alù School of Physics Central South University Changsha 410083 China Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Department of Electrical Engineering City College of The City University of New York New York 10031 USA MOE Key Laboratory of Weak-Light Nonlinear Photonics School of Physics Nankai University Tianjin 300071 China Physics Program Graduate Center City University of New York New York New York 10016 USA

Time interfaces consist of abrupt and spatially uniform changes in the optical properties of a medium. Their periodic occurrence forms photonic time crystals, which offer opportunities to tailor classical and quantum light-matter interactions. Here we explore one-dimensional photonic time quasicrystals, formed when time interfaces occur in a quasiperiodic fashion featuring long-range order. We unveil the emergence of topological phases and Hofstadter butterfly spectra in these systems, and demonstrate that their temporal response emulates the localization of topological edge states, enabling the temporal analog of topological Thouless pumping. Our findings open avenues for topological photonics leveraging time as a synthetic dimension, with functionalities that go beyond their spatial counterparts.

关键词： Quasicrystals

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Multistate Control of Nonlinear Photocurrents in Optoferroelectrics via phase manipulation of light field

arXiv

引用

arXiv 2025年

作者： Kazempour, Ali Sisakht, Esmaeil Taghizadeh Okyay, Mahmut Sait Jiang, Xiao Sato, Shunsuke Park, Noejung Department of physics Payame Noor University PO BOX Tehran119395-3697 Iran Department of Physics Ulsan National Institute of Science and Technology Ulsan689-798 Korea Republic of Materials Science and Engineering Program Department of Chemical and Environmental Engineering University of California-Riverside RiversideCA92521 United States Center for Computational Sciences University of Tsukuba Tsukuba305-8577 Japan

Ultrafast optical control of ferroelectricity based on short and intense light can be utilized to achieve accurate manipulations of ferroelectric materials, which may pave a basis for future breakthrough in nonvolatile memories. Here, we demonstrate that phase manipulation of electric field in the strong field sub-cycle regime induces a nonlinear injection current, efficiently coupling with the topology of band structure and enabling dynamic reversal of both current and polarization. Our time-dependent first-principles calculations reveal that tuning the phase of linearly or circularly polarized light through time-varying chirp, or constant carrier envelop phases within sub-laser-cycle dynamics effectively breaks the time-reversal symmetry, allowing the control over current and electronic polarization reversal over multi-ferroelectric states. Our time- and momentum-resolved transverse current analysis reveal the significance of Berry curvature higher order poles in the apparent association between the odd (even) orders of Berry curvature multipoles to odd (even) pseudo-harmonics in driving polarization dynamics reversal. We suggest that these phase manipulations of short pulse waveform may lead to unprecedented accurate control of nonlinear photocurrents and polarization states, which facilitate the development of precise ultrafast opto-ferroelectric devices. © 2025, CC BY.

关键词： Ferroelectricity

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Investigation of radiation shielding properties using MCNPX simulation and scintillation properties of Ce3+-ions doped silicate glass system

引用

Radiation physics and Chemistry 2025年 235卷

作者： Khan, I. Mukammil, S. Khan, N. Ifseisi, Ahmad A. Assal, Mohamed E. Shoaib, M. Ullah, I. Rooh, G. Lixian, Xiao YongTai, He Kaewkhao, J. Department Department of Physics Abdul Wali Khan University Mardan23200 Pakistan School of Physics and Electrical Energy Engineering Chuxiong Normal University Chuxiong675000 China Chemistry Department College of Science King Saud University P.O. 2455 Riyadh11451 Saudi Arabia Physics Program Faculty of Science and Technology Nakhon Pathom Rajabhat University Nakhon Pathom73000 Thailand Nakhon Pathom Rajabhat University Nakhon Pathom73000 Thailand

In this study the physical, structural, optical and radiation shielding characteristics of (50-x)SiO2–40Li2O–05BaO:05Gd2O3-xCeF3 (x = 0.00, 0.05, 0.1, 0.5, 1.0, 1.5 mol%) were investigated. The x-ray diffraction analysis confirms the amorphous nature of S-sample. The density and refractive index increase with Ce3+ concentration in host glasses. The molar volume is rised with Ce3+ contents in host glass from S1–S6 confirm the less compact glass structure. The shielding parameters were determined using MCNPX simulation. The linear attenuation of glass samples increase with increase of cerium oxide contents while decrease with increase of energy from 0.01 to 15 MeV. The Half Value Layer (HVL) and Tenth Value Layer (TVL) values increase with energy, indicating more thicker glass is needed to reduce radiation flux at higher energy. The effective atomic number varies randomly with energy representing different photon matter interactions in specific energy ranges. The mean free path is increased with rise of energy. Under λexc = 275 nm, two emission spectra were observed that are positioned at 312 nm and 375 nm and belong to Gd3+-ions (6P7/2 to 8S7/2) and Ce3+-ions (5d-4f) transition, respectively. The results of XEL spectra are similar to PL spectra. The integral-scintillation efficiency of LBS-Gd/Ce0.1 glass is 10.01 % that of BGO scintillator. Based on these results the developed glasses can be employed as a choice of radiation shielding material for x-rays and γ-rays in the field of medicine, hospitals, nuclear physics and has the potential for scintillator applications. © 2025 Elsevier Ltd

关键词： Gamma rays

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Leveraging ROTI map derived from Indonesian GNSS receiver network for advancing study of Equatorial Plasma Bubble in Southeast/East Asia

引用

Earth and Planetary physics 2025年第1期9卷 101-116页

作者： Prayitno Abadi Ihsan N.Muafiry Teguh N.Pratama Angga Y.Putra Suraina Gatot H.Pramono Sidik T.Wibowo Febrylian F.Chabibi Umar A.Ahmad Wildan P.Tresna Asnawi Research Center for Climate and Atmosphere Indonesian National Research and Innovation Agency(BRIN)BandungIndonesia School of Electrical Engineering Telkom UniversityBandungIndonesia Directorate of Laboratory Management Facilities and Science and Technology Park Indonesian National Research and Innovation Agency(BRIN)PontianakIndonesia Geophysics Laboratory Master Program in PhysicsUniversitas Gadjah Mada(UGM)YogyakartaIndonesia Research Center for Space Indonesian National Research and Innovation Agency(BRIN)BandungIndonesia Indonesian Geospatial Information Agency(BIG) JakartaIndonesia Research Center for Photonics Indonesian National Research and Innovation Agency(BRIN)Tangerang SelatanIndonesia Department of Earth and Planetary Sciences Hokkaido UniversitySapporoJapan

This paper highlights the crucial role of Indonesia’s GNSS receiver network in advancing Equatorial Plasma Bubble(EPB)studies in Southeast and East Asia,as ionospheric irregularities within EPB can disrupt GNSS signals and degrade positioning *** by the Indonesian Geospatial Information Agency(BIG),the Indonesia Continuously Operating Reference Station(Ina-CORS)network comprises over 300 GNSS receivers spanning equatorial to southern low-latitude ***-CORS is uniquely situated to monitor EPB generation,zonal drift,and dissipation across Southeast *** provide a practical tool for EPB research,by sharing two-dimensional rate of Total Electron Content(TEC)change index(ROTI)derived from this *** generate ROTI maps with a 10-minute resolution,and samples from May 2024 are publicly available for further scientific *** preliminary findings from the ROTI maps of Ina-CORS are ***,the Ina-CORS ROTI maps reveal that the irregularities within a broader EPB structure persist longer,increasing the potential for these irregularities to migrate farther ***,we demonstrate that combined ROTI maps from Ina-CORS and GNSS receivers in East Asia and Australia can be used to monitor the development of ionospheric irregularities in Southeast and East *** have demonstrated the combined ROTI maps to capture the development of ionospheric irregularities in the Southeast/East Asian sector during the G5 Geomagnetic Storm on May 11,*** observed simultaneous ionospheric irregularities in Japan and Australia,respectively propagating northwestward and southwestward,before midnight,whereas Southeast Asia’s equatorial and low-latitude regions exhibited irregularities *** sharing ROTI maps from Indonesia and integrating them with regional GNSS networks,researchers can conduct comprehensive EPB studies,enhancing the understanding of EPB behavior across Southeast and East Asia and contributing significantly to ionosphe

关键词： Equatorial Plasma Bubble(EPB) GNSS receivers’network Indonesia Continuously Operating Reference Station(Ina-CORS) ionospheric map Rate of TEC change index(ROTI)map

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Sodium niobate with high photocatalytic activity for the removal of organic dye and inactivation of Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae bacteria: the effect of Zn doping on these properties

引用

Ceramics International 2025年

作者： Fernandes, Daiane Raubach, Cristiane Trassante, Carla Dias, Vagner Melo, Luize Silveira, Marcelle Carvalho, Ramon Moreira, Mario Jardim, Pedro Ferrer, Mateus Giongo, Janice Vaucher, Rodrigo Longo, Elson Cava, Sergio Post-Graduate Program in Materials Science and Engineering Federal University of Pelotas RS Pelotas96010-610 Brazil Post-Graduate Program in Microbiology and Parasitology Federal University of Pelotas RS Capão do Leão96160-000 Brazil Post-Graduate Program in Physics Federal University of Pelotas RS Capão do Leão96160-000 Brazil Functional Materials Development Center São Carlos Federal University SP São Carlos13565-905 Brazil

NaNbO3 doped with Zn (0.00, 0.02, and 0.05 mmol) was synthesized by the microwave-assisted hydrothermal method. Photocatalytic and antibacterial activities were investigated. X-ray diffraction revealed the coexistence of two orthorhombic symmetries (P21ma and Pbma), with doping promoting a progressive increase in the Pbma fraction. All samples exhibited a fiber-like shape (diameter of ∼200 nm), which remained unchanged with doping. The low Zn content (0.02 mmol) reduced the band gap energy from 3.08 to 2.95 eV. As a result, this sample exhibited superior photocatalytic activity, achieving 100 % RhB dye degradation within 45 min, under UV light. Scavenger tests revealed that hydroxyl radicals, holes, and superoxide radical anions were the main active species involved in the photocatalytic reaction. Additionally, the photocatalyst demonstrated excellent recyclability over three consecutive cycles. Pure NaNbO3 exhibited strong antibacterial activity, completely inhibiting the growth of S. aureus, E. coli, and K. pneumoniae at the tested concentrations. Although the Zn-doped sample also demonstrated antibacterial action, the response was concentration-dependent. This study is the first report on Zn doping in NaNbO3, as well as the first investigation of its antibacterial activity against K. pneumoniae and S. aureus. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Escherichia coli

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Dynamical evolution of critical fluctuations with second-order baryon diffusion coupled to chiral condensate

arXiv

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arXiv 2025年

作者： Sakai, Azumi Murase, Koichi Fujii, Hirotsugu Hirano, Tetsufumi Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan Department of Physics Sophia University Chiyoda Tokyo102-8554 Japan Department of Physics Tokyo Metropolitan University Hachioji Tokyo192-0397 Japan Yukawa Institute for Theoretical Physics Kyoto University Sakyo Kyoto606-8502 Japan International Politics and Economics Nishogakusha University Chiyoda Tokyo102-8336 Japan Institute of Physics Unviversity of Tokyo Meguro Tokyo153-8902 Japan

We develop a dynamical model to describe critical fluctuations in heavy-ion collisions, incorporating the baryon diffusion current and chiral condensate as dynamical degrees of freedom, to address their nontrivial scale separation. The model couples fluctuations of the chiral condensate σ with baryon density fluctuations n and the diffusion current ν based on a second-order diffusion equation with a finite relaxation time of the baryon diffusion τR. We analyze the spacetime evolution and these correlation functions of the fluctuations in one-dimensionally expanding background. We confirm that an appropriate relaxation time τR ensures causality. We show that propagating waves with finite τR split into two modes at the critical temperature due to a rapid change of kinetic coefficients. In the correlation functions, we find that dynamical σ blurs the structure and peak around the critical temperature. With finite τR, the effect of the critical fluctuations persists longer into the later stages of the evolution. These findings suggest importance of dynamical effects of the chiral condensate and baryon diffusion current in identifying critical-point signals in heavy-ion collisions, where the scale separation is nontrivial. Copyright © 2025, The Authors. All rights reserved.

关键词： Heavy ions

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