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arXiv 2025年

作者： Wang, Shaoyun Shao, Nan Chen, Hui Chen, Jiaji Qian, Honghua Wu, Qian Duan, Huiling Alù, Andrea Huang, Guoliang Department of Mechanical and Aerospace Engineering University of Missouri ColumbiaMO65211 United States Center for Mechanics Plus Under Extreme Environments School of Mechanical Engineering and Mechanics Ningbo University Ningbo315211 China Photonics Initiative Advanced Science Research Center City University of New York New YorkNY United States Physics Program Graduate Center City University of New York New YorkNY United States Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China

Wave reflection and refraction at a time interface follow different conservation laws compared to conventional scattering at a spatial interface. This study presents the experimental demonstration of refraction and reflection of flexural waves across a temporal boundary in a continuum-based mechanical metabeam, and unveils opportunities that emerge by tailoring temporal scattering phenomena for phononic applications. We observe these phenomena in an elastic beam attached to an array of piezoelectric patches that can vary in time the effective elastic properties of the beam. Frequency conversion and phase conjugation are observed upon a single temporal interface. These results are consistent with the temporal Snell’s law and Fresnel equations for temporal interfaces. Further, we illustrate the manipulation of amplitude and frequency spectra of flexural wave temporal refraction and reflection through multi-stepped temporal interfaces. Finally, by implementing a smooth time variation of wave impedance, we numerically and experimentally demonstrate the capabilities of the temporal metabeam to realize waveform morphing and information coding. Our findings lay the foundation for developing time-mechanical metamaterials and time-phononic crystals, offering new avenues for advanced phonon manipulation in both wave amplitude and frequency. © 2025, CC BY.

关键词： Phonons

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Gyromagnetic Angular Momentum Interconversion in Neutron Stars

arXiv

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arXiv 2025年

作者： Funaki, Hiroshi Sekino, Yuta Tajima, Hiroyuki Kisaka, Shota Yasutake, Nobutoshi Matsuo, Mamoru Kavli Institute for Theoretical Sciences University of Chinese Academy of Sciences Beijing100190 China RIKEN Saitama Wako351-0198 Japan Saitama Wako351-0198 Japan Saitama Wako351-0198 Japan Department of Physics School of Science The University of Tokyo Tokyo113-0033 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima739-8526 Japan 2-1-1 Shibazono Chiba Narashino275-0023 Japan Advanced Science Research Center Japan Atomic Energy Agency Tokai319-1195 Japan CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100190 China Saitama Wako351-0198 Japan

We propose a novel mechanism for angular momentum (AM) exchange between the crust and core of a neutron star (NS) via the gyromagnetic effect. Using extended hydrodynamics, we model the star by incorporating macroscopic AM and microscopic AM originating from neutron orbital and spin AM. We reveal that macroscopic dynamics in the crust can inform microscopic AM in the core leading to neutron spin polarization, and offer alternative scenario of (anti-)glitches. This work highlights the overlooked multi-scale AM interconversions in NS physics, paving the way for gyromagnetic astrophysics. Copyright © 2025, The Authors. All rights reserved.

关键词： Spin polarization

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Computational design of serine hydrolases

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science (New York, N.Y.) 2025年第6744期388卷 eadu2454页

作者： Lauko, Anna Pellock, Samuel J. Sumida, Kiera H. Anishchenko, Ivan Juergens, David Ahern, Woody Jeung, Jihun Shida, Alexander F. Hunt, Andrew Kalvet, Indrek Norn, Christoffer Humphreys, Ian R. Jamieson, Cooper Krishna, Rohith Kipnis, Yakov Kang, Alex Brackenbrough, Evans Bera, Asim K. Sankaran, Banumathi Houk, K.N. Baker, David Department of Biochemistry University of Washington Seattle WA United States Institute for Protein Design University of Washington Seattle WA United States Graduate Program in Biological Physics Structure and Design University of Washington Seattle WA United States Department of Chemistry University of Washington Seattle WA United States Graduate Program in Molecular Engineering University of Washington Seattle WA United States Paul G. Allen School of Computer Science and Engineering University of Washington Seattle WA United States Medical Scientist Training Program University of Washington Seattle WA United States Howard Hughes Medical Institute University of Washington Seattle WA United States Department of Chemistry and Biochemistry University of California Los Angeles CA United States

The design of enzymes with complex active sites that mediate multistep reactions remains an outstanding challenge. With serine hydrolases as a model system, we combined the generative capabilities of RFdiffusion with an ensemble generation method for assessing active site preorganization at each step in the reaction to design enzymes starting from minimal active site descriptions. Experimental characterization revealed catalytic efficiencies (kcat/Km) up to 2.2 × 105 M-1 s-1 and crystal structures that closely match the design models (Cα root mean square deviations <1 angstrom). Selection for structural compatibility across the reaction coordinate enabled identification of new catalysts remove with five different folds distinct from those of natural serine hydrolases. Our de novo approach provides insight into the geometric basis of catalysis and a roadmap for designing enzymes that catalyze multistep transformations.

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Active modulation of plasmonic signal with a subwavelength metal/nonlinear dielectric material/metal structure

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Chinese Optics Letters 2010年第6期8卷 584-587页

作者：王小蕾王沛陈春翀陈俊学鲁拥华明海詹其文 Department of Physics Anhui Key Laboratory of Optoelectronic Science and TechnologyUniversity of Science and Technology of China Electro-Optics Graduate Program University of Dayton300 College ParkDaytonOH 45469USA

Light propagation through a metal/nonlinear dielectric material/metal（M-NL-M） structure is numerically *** design parameters of the M-NL-M structure are found with the waveguide theory so that the structure only supports the symmetric surface plasmon polaritons（SPP（0）） mode and the antisymmetric surface plasmon polaritons（SPP（1）） *** coupling between the two modes within the M-NL-M structure is *** controlling the propagation constants of the two modes with the intensity-dependent dielectric constant of the nonlinear Kerr material,an effective all-optical control of plasmonic signal modulator can be realized with this M-NL-M structure.

关键词： Modulation Phonons Photons Quantum theory Solids

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Ion-Implantation, Epilayer Growth, and Lift-Off of High-Quality Diamond Films

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Advanced Functional Materials 2025年

作者： Zhang, Xiang Pieshkov, Tymofii S. Chen, Di Nonis, Suresh Ngan, Kinfung Oliveira, Eliezer F. Gray, Tia Biswas, Abhijit Puthirath, Anand B. Pate, Bradford B. Garratt, Elias J. Birdwell, A. Glen Neupane, Mahesh R. Ivanov, Tony Sun, Shuo Vajtai, Robert Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Texas Center for Superconductivity University of Houston HoustonTX77204 United States JILA and Department of Physics University of Colorado BoulderCO80309 United States SP Bauru17033-360 Brazil Chemistry Division Naval Research Laboratory WashingtonDC20375 United States DEVCOM Army Research Laboratory RF Devices and Circuits AdelphiMD20783 United States

The development of high-quality diamond films is pivotal for driving advances in quantum technology, power electronics, and thermal management. The ion implantation and lift-off technique has emerged as a crucial method for fabricating diamond films with controlled thickness and scalable production of large-area diamond wafers. This study advances the understanding of critical interface dynamics during diamond epilayer growth on ion-implanted commercial diamond substrates. Leveraging high-resolution cross-sectional electron microscopy and spectroscopic analyses, the direct transformation of the damaged diamond layer is revealed into a graphitic layer during epilayer overgrowth, eliminating the need for high-temperature annealing. Raman and photoluminescence spectroscopy mappings along the side section highlight the exceptional quality and purity of the epilayer, showcasing nitrogen-vacancy center densities comparable to electronic-grade diamond, making it highly suitable for quantum and electronic applications. Finally, the epilayer detaches efficiently via electrochemical etching, leaving a substrate with low surface roughness that is reusable for multiple growth cycles. These results provide valuable insights into refining the ion implantation and lift-off process, bridging critical gaps in interface evolution, and establishing a foundation for sustainable, high-performance diamond films across diverse technological applications. © 2025 Wiley-VCH GmbH.

关键词： Photoluminescence spectroscopy

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Enhancing Diagnostic Accuracy for Knee Osteoarthritis Using a Deep Learning Approach

Enhancing Diagnostic Accuracy for Knee Osteoarthritis Using ...

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International Symposium on Applied science 2024, ISAS 2024

作者： Raza, Aquib Ching, Congo Tak Shing Liu, Peng-Ta Phan, Thien-Luan Tran, Ngoc-Luan Nguyen, Ha Anh T. Rameez, Mohammad Li, Hung-Chung Linh, Dao Nguyen Phuong Van Hieu, Nguyen Tran, Trung Nghia National Taiwan University Taipei City10673 Taiwan Research Center for Information Technology Academia Sinica Taipei City11529 Taiwan Graduate Institute of Biomedical Engineering National Chung Hsing University Taichung402 Taiwan Department of Electrical Engineering National Chi Nan University Nantou County Taiwan Advanced Plant and Food Crop Biotechnology Center National Chung Hsing University Taichung402 Taiwan International Doctoral Program in Agriculture National Chung Hsing University Taichung402 Taiwan Fall Prevention Center Department of Physical Medicine & Rehabilitation Changhua Christian Hospital Changhua500 Taiwan Department of Physics and Electronic Engineering University of Science Vietnam National University - Ho Chi Minh City Ho Chi Minh City70000 Viet Nam Department of Computer Science University of York York HeslingtonYO10 5DD United Kingdom Undergraduate Program of Intellectual Creativity Engineering National Chung Hsing University Taichung402 Taiwan Ho Chi Minh City72409 Viet Nam HCMUT Vietnam National University Ho Chi Minh City Thu Duc Ho Chi Minh City71308 Viet Nam

This research introduces a deep learning framework that combines convolutional neural networks with autoencoders to improve the diagnostic accuracy of knee osteoarthritis. The study utilized a publicly available dataset from the Mendeley Data repository, where knee joint images were preprocessed using Contrast Limited Adaptive Histogram Equalization to enhance contrast and ensure consistent image sizing. Initially, an autoencoder was employed in an unsupervised manner to learn compressed representations of the data. These representations were then used to train a CNN to classify knee images into 'healthy' and 'osteoarthritic' categories. The model was trained using an 80:20 split for training and testing data, incorporating early stopping and data augmentation techniques to prevent overfitting and enhance generalization. Performance metrics such as accuracy, precision, recall, and the area under the Receiver Operating Characteristic curve (ROCAUC) were used to evaluate the model, resulting in a high test accuracy of 98.95%. The high precision and recall rates further confirmed the model's robustness in diagnosing KOA. To enhance interpretability, Gradient-weighted Class Activation Mapping (Grad-CAM) was applied to identify critical regions in the images that influenced the model's decisions. Additionally, t-Distributed Stochastic Neighbor Embedding (t-SNE) was used to visualize the high-dimensional encoded features in a two-dimensional space, providing deeper insights into how the model differentiates between classes. The promising results of this deep learning approach suggest its potential for broader applications in medical imaging diagnostics. By providing healthcare professionals with a tool that enhances diagnostic accuracy and operational efficiency, this framework lays the foundation for developing scalable, AI-driven diagnostic systems for various complex medical conditions. © 2025 Institute of physics Publishing. All rights reserved.

关键词： Joints (anatomy)

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Ultrafast carrier dynamics and layer-dependent carrier recombination rate in InSe

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Nanoscale 2023年第7期15卷 3169-3176页

作者： Wu, Ting-Hsuan Cheng, Hao-Yu Lai, Wei-Chiao Sankar, Raman Chang, Chia-Seng Lin, Kung-Hsuan Department of Physics National Taiwan University Taipei106319 Taiwan Institute of Physics Academia Sinica Taipei115201 Taiwan Nano-Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei115201 Taiwan

InSe layered semiconductors with high mobility have advantages over transition-metal dichalcogenides in certain device applications. Understanding the dynamics of carriers, especially around the major bandgaps, is not only of fundamental interest but also important for improving the performance of devices. We investigated ultrafast carrier dynamics in exfoliated InSe near the bandgap and found that the presence of photocarriers led to shrinkage in the optical bandgap. In addition, we observed that the carrier recombination rate increased when the thickness of the InSe nanoflakes was reduced and the process was dominated by surface recombination. For the same flakes, the recombination rate became lower after the freshly exfoliated InSe was exposed to air and oxidized. Using a free carrier diffusion model, layer-dependent surface recombination velocities were obtained. Our investigation reveals that the surface condition and the thickness of few-layer InSe play important roles in carrier lifetimes. © 2023 The Royal Society of Chemistry.

关键词： Energy gap

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Influence of Ba/Fe mole ratios on magnetic properties, crystallite size and shifting of X-ray diffraction peaks of nanocrystalline BaFe₁₂O₁₉ powder, prepared by sol gel auto combustion

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AIP Conference Proceedings 2011年第1期1454卷 238-241页

作者： Suastiyanti, Dwita Sudarmaji, Arif Soegijono, Bambang Graduate Program of Materials Science Department of Physics University of Indonesia Indonesia Multiferroic Laboratory Department of Physics University of Indonesia Indonesia

Barium hexaferrite BaFe12O19 (BFO) is of great importance as permanent magnets, particularly for magnetic recording as well as in microwave devices. Nano-crystalline BFO powders were prepared by sol gel auto combustion method in citric acid - metal nitrates system. Hence the mole ratios of Ba/Fe were variated at 1:12;1:11.5 and 1:11. Ratio of cation to fuel was fixed at 1:1. An appropriate amount of amonia solution was added dropwise to this solution with constant stirring until the PH reached 7 in all cases. Heating at 850oC for 10 hours for each sample to get final formation of BFO nanocrystalline. The data from XRD showing the lattice parameters a,c and the unit-cell volume V, confirm that BFO with ratio 1:12 has same crystall parameters with ratio 1:11. Ratio of Ba/Fe 1:12 and 1:11 have diffraction pattern similarly at almost each 2 Θ for each samples. Ratio of Ba/Fe 1: 11.5 has the finest crystallite size 22 nm. Almost diffraction pattern peaks of Ba/Fe 1:11.5 move to the left from of Ba/Fe 1:12 then return to diffraction pattern of Ba/Fe 1:12 for Ba/Fe 1:11. SEM observations show the particle size less than 100 nm and the same shape for each sample. Ratio of Ba/Fe 1: 12 gives the highest intrinsic coercive Hc = 427.3 kA/m. The highest remanent magnetization is at ratio 1:11 with Mr = 0.170 T. BFO with mole ratio 1:11.5 has the finest grain 22 nm, good magnetic properties and the highest value of best FoM 89%. © 2012 American Institute of physics.

关键词： Magnetic properties Nano crystalline barium hexaferrite Sol gel auto combustion

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Green synthesis of Ni, Co-based oxides for water oxidation applications

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Materials science in Semiconductor Processing 2025年 195卷

作者： Andrade, Verônica de M. Lopes, Sávio M. Raimundo, Rafael A. Alves, Ricardo F. Araújo, Allan J.M. Vieira, Pamala S. da Silva, Fausthon F. Morales, Marco A. Macedo, Daniel A. Fagg, Duncan P. Souza, Glageane da S. Academic Unit of Biology and Chemistry Federal University of Campina Grande PB Cuité58175-000 Brazil Materials Science and Engineering Graduate Program UFPB João Pessoa58051-900 Brazil TEMA - Centre for Mechanical Technology and Automation Department of Mechanical Engineering University of Aveiro Aveiro3810-193 Portugal Federal University of Paraíba Department of Mechanical Engineering PB João Pessoa58051-900 Brazil LASI - Intelligent Systems Associate Laboratory Guimarães4800-058 Portugal Materials Science and Engineering Postgraduate Program Federal University of Rio Grande do Norte Natal59078-970 Brazil Department of Chemistry Federal University of Paraíba Paraíba João Pessoa58051-900 Brazil Department of Theoretical and Experimental Physics Federal University of Rio Grande do Norte RN Natal59078-970 Brazil

This work reports new Ni,Co-oxides based nanoparticles as electrocatalysts for the Oxygen Evolution Reaction (OER), considering the growing demand for renewable energy, as well as the search for sustainable alternatives in the production of nanoparticle materials. Ni,Co-based nanoparticles were obtained via proteic sol-gel method, with Agar-Agar from red seaweed (Rhodophyta) as polymerizing agent, and characterized by using X-ray diffraction techniques (including Rietveld refinement), Field emission scanning electron microscopy and vibrational spectroscopy (infrared and Raman). All structural analyses indicated that the crystalline phases NiO, Ni0.9Co0.1O and (Ni,Co)O-Co3O4 were obtained. Electrochemical techniques were applied to investigate the OER electrocatalytic performance, with the (Ni,Co)O-Co3O4 electrocatalyst showing the lowest overpotential (356 mV vs. RHE at J = 10 mA cm−2) and a Turnover Frequency (TOF) of 9.97 × 10−3 mol O2 s−1 at just 500 mV vs. RHE. Furthermore, all prepared electrocatalysts showed excellent chemical stability up to 15 h, as indicated in chronopotentiometry data. © 2025 Elsevier Ltd

关键词： Rietveld refinement

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Synthesis and characterization of few-layered carbon nanotubes decorated with magnetic nanoparticles envisaging potential technological applications

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Surfaces and Interfaces 2025年 66卷

作者： da Silva, Wellington Marcos da Silva, Mauro Francisco Pinheiro de Souza, Rodrigo Nunes Silva, Alysson Martins Almeida Rodrigues, Alisson Mendes Santos, Alexandre Silva da Silva, SebastiãoWilliam Mohallem, Nelcy Della Santina Coaquira, José Antonio Huamaní Graduate Program in Materials Science (PPGCIMA) Faculty UnB Planaltina (FUP) University of Brasília DF Brasilia 73.345-010 Brazil International Center of Physics Institute of Physics Campus Universitário Darcy Ribeiro University of Brasilia DF Brasilia 70.910-900 Brazil Mechanical Engineering Department Faculty of Technology Campus Universitário Darcy Ribeiro University of Brasilia DF Brasilia 70.910-900 Brazil Institute of Physics University of Brasilia Campus Universitário Darcy Ribeiro DF Brasilia 70.910-900 Brazil Department of Chemistry Institute of Exact Sciences Federal University of Minas Gerais Belo Horizonte-MG MG 31270-901 Brazil

In this work, high-quality few-layered carbon nanotubes (CNTs) were synthesized using a novel iron-oxide/sulfur-based catalyst via the chemical vapor deposition method (CVD). To enable external magnetic control for potential technological applications, CNTs incorporating magnetic nanoparticles were also produced. An efficient synthesis route, employing a microwave-assisted reaction, was used to generate and integrate the iron oxide nanoparticles and CNTs. The synthesized nanomaterials were thoroughly characterized using X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA/DTA), transmission electron microscopy (TEM) and magnetic measurements. The results indicate that the few-layered CNTs (sample CNT-Ox) exhibit a magnetic response, which is further modified upon the incorporation of magnetic nanoparticles (sample CNT-Ox-Mag), suggesting an effective interaction between the CNTs and the magnetic nanoparticles. However, after a reduction process (sample CNT-Ox-Mag-Red), the magnetization increases approximately 20-fold compared to the other two samples. This significant enhancement reflects the presence of a substantial amount (∼48 %) of metallic iron primarily located within the CNTs channel. Raman spectroscopy revealed characteristic bands at 261 and 263 cm⁻¹, confirming the presence of single and few-layered CNTs. TEM images further demonstrate that the nanoparticles are encapsulated within the CNTs. These findings indicate the successful formation of a hybrid CNTs/magnetic nanoparticles system, which serve as a multifunctional platform with promising potential for technological applications. © 2025 Elsevier B.V.

关键词： Carbon nanotubes Magnetic nanoparticles Magnetic properties Novel catalyst Synthesis

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