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arXiv 2024年

作者： Rennich, Emily Sung, Suk Hyun Agarwal, Nishkarsh Gates, Maya Kerns, Robert Hovden, Robert Baggari, Ismail El The Rowland Institute at Harvard Harvard University CambridgeMA02142 United States Department of Mechanical Engineering University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Michigan Center for Materials Char-acterization University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States

Cryogenic transmission electron microscopy has revolutionized structural biology and materials science, but achieving temperatures below the boiling point of liquid nitrogen remains a long-standing aspiration. We introduce an ultra-cold liquid helium transmission electron microscope specimen holder, featuring continuous cryogen flow and vibration decoupling. This instrument is compatible with modern aberration-corrected microscopes and achieves sub-25 K base temperature, ±2 mK thermal stability over many hours, and atomic resolution—setting the stage for a new era of cryogenic electron microscopy. © 2024, CC BY.

关键词： High resolution transmission electron microscopy

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Local and global measures of the shear moduli of jammed disk packings

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Physical Review E 2023年第5期107卷 054903-054903页

作者： Shiyun Zhang Weiwei Jin Dong Wang Ding Xu Jerry Zhang Mark D. Shattuck Corey S. O'Hern Department of Physics University of Science and Technology of China Hefei Anhui 230026 China Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA Graduate Program in Computational Biology and Bioinformatics Yale University New Haven Connecticut 06520 USA

Strain-controlled isotropic compression gives rise to jammed packings of repulsive, frictionless disks with either positive or negative global shear moduli. We carry out computational studies to understand the contributions of the negative shear moduli to the mechanical response of jammed disk packings. We first decompose the ensemble-averaged, global shear modulus as 〈G〉=(1−F−)〈G+〉+F−〈G−〉, where F− is the fraction of jammed packings with negative shear moduli and 〈G+〉 and 〈G−〉 are the average values from packings with positive and negative moduli, respectively. We show that 〈G+〉 and 〈|G−|〉 obey different power-law scaling relations above and below pN2∼1. For pN2>1, both 〈G+〉N and 〈|G−|〉N∼(pN2)β, where β∼0.5 for repulsive linear spring interactions. Despite this, 〈G〉N∼(pN2)β′ with β′≳0.5 due to the contributions from packings with negative shear moduli. We show further that the probability distribution of global shear moduli P(G) collapses at fixed pN2 and different values of p and N. We calculate analytically that P(G) is a Γ distribution in the pN2≪1 limit. As pN2 increases, the skewness of P(G) decreases and P(G) becomes a skew-normal distribution with negative skewness in the pN2≫1 limit. We also partition jammed disk packings into subsystems using Delaunay triangulation of the disk centers to calculate local shear moduli. We show that the local shear moduli defined from groups of adjacent triangles can be negative even when G>0. The spatial correlation function of local shear moduli C(r⃗) displays weak correlations for pnsub2<10−2, where nsub is the number of particles within each subsystem. However, C(r⃗) begins to develop long-ranged spatial correlations with fourfold angular symmetry for pnsub2≳10−2.

关键词： Jamming Packing & jamming problems Granular materials

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Structural, optical, and electronic properties of barium titanate: experiment characterisation and first-principles study

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materials and Processing Report 2022年第14期37卷 2995-3005页

作者： Mohammed Tihtih Jamal Eldin F. M Ibrahim Mohamed A. Basyooni Walid Belaid László A. Gömze István Kocserha a Institute of Ceramic and Polymer Engineering University of Miskolc Miskolc Hungary b Department of Nanotechnology and Advanced Materials Graduate School of Applied and Natural Science Selçuk University Konya Turkeyc Science and Technology Research and Application Center (BITAM) Necmettin Erbakan University Konya Turkey d Department of Physics Faculty of Science Selçuk University Konya Turkey a Institute of Ceramic and Polymer Engineering University of Miskolc Miskolc Hungarye Department of Mechanics of Deformed Solids National Research Tomsk State University Tomsk Russia

ABSTRACTABSTRACTTo study the structural, electronic, and optical properties of lead-free Barium titanate BaTiO3(BT) ferroelectric material in its tetragonal structure, a combination of experimental and theoretical studies has been used and the obtained results were discussed. The studied BT compound was prepared via the sol–gel technique. The calculated bandgap energy (Eg) and structural parameters of BT are determined using four types of exchange–correlation functionals (PBE, PBEsol, LDA, and PW91) in the perspective of the density functional theory (DFT). XRD and Raman analysis have shown that BT ceramic exhibits a tetragonal phase structure without any trace of impurity phases. The UV–vis investigation showed that BT has a bandgap energy of 3.19 eV, which is larger than the theoretically calculated values. The computed lattice parameter c is overestimated (as large as ~1% deviation) when using the LDA approximation. In contrast, PBEsol proved that those lattice constants were close to the experimental values (a deviation of less than 1%).

关键词： BaTiO3 sol-gel DFT spectroscopy band structure

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Thermal Conductivity of Water at Extreme Conditions

arXiv

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arXiv 2023年

作者： Zhang, Cunzhi Puligheddu, Marcello Zhang, Linfeng Car, Roberto Galli, Giulia Pritzker School of Molecular Engineering University of Chicago ChicagoIL60637 United States Materials Science Division Center for Molecular Engineering Argonne National Laboratory LemontIL60439 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Department of Chemistry Department of Physics Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08544 United States Department of Chemistry University of Chicago ChicagoIL60637 United States

Measuring the thermal conductivity (κ) of water at extreme conditions is a challenging task and few experimental data are available. We predict κ for temperatures and pressures relevant to the conditions of the Earth mantle, between 1,000 and 2,000 K and up to 22 GPa. We employ close to equilibrium molecular dynamics simulations and a deep neural network potential fitted to density functional theory data. We then interpret our results by computing the equation of state of water on a fine grid of points and using a simple model for κ. We find that the thermal conductivity is weakly dependent on temperature and monotonically increases with pressure with an approximate square-root behavior. In addition we show how the increase of κ at high pressure, relative to ambient conditions, is related to the corresponding increase in the sound velocity. Although the relationships between the thermal conductivity, pressure and sound velocity established here are not rigorous, they are sufficiently accurate to allow for a robust estimate of the thermal conductivity of water in a broad range of temperatures and pressures, where experiments are still difficult to perform. Copyright © 2023, The Authors. All rights reserved.

关键词： Thermal conductivity

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Suppression of thermal postbuckling and nonlinear panel flutter motions of variable stiffness composite laminates using piezoelectric actuators

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Journal of Central South University 2021年第12期28卷 3757-3777页

作者： TAO Ji-xiao YI Sheng-hui DENG Ya-jie HE Xiao-qiao Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen 518055China Centre for Advanced Structural Materials City University of Hong Kong Shenzhen Research InstituteShenzhen 518057China School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China Department of Architecture and Civil Engineering City University of Hong KongTat Chee AvenueKowloonHong KongChina

Variable stiffness composite laminates(VSCLs)are promising in aerospace engineering due to their designable material properties through changing fiber angles and stacking *** to control the thermal postbuckling and nonlinear panel flutter motions of VSCLs,a full-order numerical model is developed based on the linear quadratic regulator(LQR)algorithm in control theory,the classical laminate plate theory(CLPT)considering von Kármán geometrical nonlinearity,and the first-order Piston *** critical buckling temperature and the critical aerodynamic pressure of VSCLs are parametrically *** location and shape of piezoelectric actuators for optimal control of the dynamic responses of VSCLs are determined through comparing the norms of feedback control gain(NFCG).Numerical simulations show that the temperature field has a great effect on aeroelastic tailoring of VSCLs;the curvilinear fiber path of VSCLs can significantly affect the optimal location and shape of piezoelectric actuator for flutter suppression;the unstable panel flutter and the thermal postbuckling deflection can be suppressed effectively through optimal design of piezoelectric patches.

关键词： active control finite element method linear quadratic regulator algorithm nonlinear flutter thermal postbuckling variable stiffness composite laminates

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Nernst-Ettingshausen effect in thin Pt and W films at low temperatures

arXiv

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arXiv 2023年

作者： Luo, Renjie Legvold, Tanner J. Chen, Liyang Natelson, Douglas Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States

As spin caloritronic measurements become increasingly common techniques for characterizing material properties, it is important to quantify potentially confounding effects. We report measurements of the Nernst-Ettingshausen response from room temperature to 5 K in thin film wires of Pt and W, metals commonly used as inverse spin Hall detectors in spin Seebeck characterization. Johnson-Nyquist noise thermometry is used to assess the temperature change of the metals with heater power at low temperatures, and the thermal path is analyzed via finite-element modeling. The Nernst-Ettingshausen response of W is found to be approximately temperature-independent, while the response of Pt increases at low temperatures. These results are discussed in the context of theoretical expectations and the possible role of magnetic impurities in Pt. Copyright © 2023, The Authors. All rights reserved.

关键词： Inverse problems

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Constructing conjugated microporous polymers containing triphenylamine moieties for high-performance capacitive energy storage

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Polymer 2023年 264卷

作者： Samy, Maha Mohamed Gamal Mohamed, Mohamed Sharma, Santosh U. Chaganti, Swetha V. Hassan Mansoure, Tharwat Lee, Jyh-Tsung Chen, Tao Kuo, Shiao-Wei Department of Materials and Optoelectronic Science College of Semiconductor and Advanced Technology Research Center for Functional Polymers and Supramolecular Materials National Sun Yat-Sen University Kaohsiung804 Taiwan Chemistry Department Faculty of Science Assiut University Assiut71515 Egypt International PhD Program for Science National Sun Yat-sen University Kaohsiung80424 Taiwan Department of Chemistry National Sun Yat-Sen University Kaohsiung80424 Taiwan Ningbo Institute of Material Technology and Engineering Chinese Academy of Science Ningbo315201 China Department of Medicinal and Applied Chemistry Kaohsiung Medical University Kaohsiung807 Taiwan

In this research we developed two triphenylamine (TPA)-linked conjugated microporous polymers (CMPs), TPA-TAB and TPA-TBN, through Suzuki couplings of tris(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)amine (TPA-BO) with the aryl bromides tetrakis(4-bromophenyl)benzidine (TAB-Br4) and 2,7,10,15-tetrabromotetrabenzonaphthalene (TBN-Br4), respectively. These CMPs, which have substantial surface surfaces and outstanding thermal stability, could be employed as electrode materials in supercapacitor (SC) devices. In a three-electrode SC, the TPA-TAB CMP exhibited ultrahigh specific capacitance (684 F g−1 at 0.5 A g−1) and long-term stability, with a capacitance retention of 99.5% after 5000 cycles (at 10 A g−1). Moreover, a two-electrode symmetric SC incorporating TPA-TAB CMP presented a capacitance of 117 F g−1 and a high retention of 98% when subjected to 5000 cycles at 10 A g−1. This exceptional performance resulted from was achieved through the use of redox-active TPA units and a large BET surface area (490 m2 g−1). Accordingly, such TPA-CMPs appear to have promise for use in charge and energy storage applications. © 2022 Elsevier Ltd

关键词： Supercapacitor

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A Tendon-Driven Origami Hopper Triggered by Proprioceptive Contact Detection 3

A Tendon-Driven Origami Hopper Triggered by Proprioceptive C...

引用

3rd IEEE International Conference on Soft Robotics, RoboSoft 2020

作者： Chen, Wei-Hsi Misra, Shivangi Caporale, J. Diego Koditschek, Daniel E. Yang, Shu Sung, Cynthia R. University of Pennsylvania Department of Electrical and Systems Engineering United States University of Pennsylvania Department of Computer and Information Science United States University of Pennsylvania Department of Mechanical Engineering and Applied Mechanics United States University of Pennsylvania Department of Materials Science and Engineering United States

ISBN: (纸本)9781728165707

We report on experiments with a laptop-sized (0.23m, 2.53kg), paper origami robot that exhibits highly dynamic and stable two degree-of-freedom (circular boom) hopping at speeds in excess of 1.5 bl/s (body-lengths per second) at a specific resistance O(1) while achieving aerial phase apex states 25% above the stance height over thousands of cycles. Three conventional brushless DC motors load energy into the folded paper springs through pulley-borne cables whose sudden loss of tension upon touchdown triggers the release of spring potential that accelerates the body back through liftoff to flight with a 20W powerstroke, whereupon the toe angle is adjusted to regulate fore-aft speed. We also demonstrate in the vertical hopping mode the transparency of this actuation scheme by using proprioceptive contact detection with only motor encoder sensing. The combination of actuation and sensing shows potential to lower system complexity for tendon-driven robots. © 2020 IEEE.

关键词： Antennas

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Efficient First-Principles Framework for Overdamped Phonon Dynamics and Anharmonic Electron-Phonon Coupling in Superionic materials

arXiv

引用

arXiv 2025年

作者： Wang, Yuxuan Zacharias, Marios Zhang, Xiao Pant, Nick Even, Jacky Poudeu, Pierre F.P. Kioupakis, Emmanouil Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Univ Rennes INSA Rennes CNRS Institut FOTON - UMR 6082 RennesF-35000 France Applied Physics Program University of Michigan Ann ArborMI48109 United States Oden Institute for Computational Engineering and Sciences The University of Texas at Austin AustinTX78712 United States

Relying on the anharmonic special displacement method, we introduce an ab initio quasistatic polymorphous framework to describe local disorder, anharmonicity, and electron-phonon coupling in superionic conductors. Using the example of cubic Cu2Se, we show that positional polymorphism yields extremely overdamped anharmonic vibrations while preserving transverse acoustic phonons, consistent with experiments. We also demonstrate well-defined electronic band structures with large band gap openings due to polymorphism of 1.0 eV and calculate anharmonic electron-phonon renormalization, yielding band gap narrowing with increasing temperature in agreement with previous measurements. Our approach opens the way for efficient ab initio electronic structure calculations in superionic crystals to elucidate their compelling high figure-of-merit. © 2025, CC BY-NC-ND.

关键词： Energy gap

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Rapidly Reversible Superwettability on Textured Metallic Surfaces

SSRN

引用

SSRN 2024年

作者： Zou, Xianrui Zhang, Yongguang Fang, Wei Jiang, Hui Yang, Zhilu Li, Qunyang Wu, Shuilin Wang, Hongshui Wang, Donghui Zhou, Huan Yang, Tai Xia, Dan Liu, Ning Yang, Qiang Yang, Lei Feng, Xiqiao Liang, Chunyong Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology School of Materials Science and Engineering Hebei University of Technology Tianjin300130 China Applied Mechanics Laboratory Department of Engineering Mechanics Institute of Biomechanics and Medical Engineering Tsinghua University Beijing100084 China School of Materials Science and Engineering Tianjin University Tianjin300350 China Tianjin Key Laboratory of Composite and Functional Materials Tianjin300350 China Key Laboratory of Advanced Ceramics and Machining Technology Ministry of Education Tianjin300350 China Tianjin Key Laboratory of Molecular Optoelectronic Sciences Tianjin300350 China Dongguan Key Laboratory of Smart Biomaterials and Regenerative Medicine The Tenth Affiliated Hospital of Southern Medical University Guangdong Dongguan523059 China Guangdong Provincial Key Laboratory of Cardiac Function and Microcirculation Guangdong Guangzhou510080 China Department of Cardiology Third People's Hospital of Chengdu Affiliated to Southwest Jiaotong University Sichuan Chengdu610031 China State Key Laboratory of Tribology in Advanced Equipment Tsinghua University Beijing100084 China School of Materials Science & Engineering Peking University Beijing100871 China Biomedical Materials Engineering Research Center Hubei Key Laboratory of Polymer Materials Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials School of Materials Science & Engineering State Key Laboratory of Biocatalysis and Enzyme Engineering Hubei University Wuhan430062 China Center for Health Science and Engineering Hebei Key Laboratory of Biomaterials and Smart Theranostics School of Health Sciences and Biomedical Engineering Hebei University of Technology Tianjin300130 China Department of Spine Surgery Tianjin Hospital Tianjin University Tianjin30021 China

Reversible superwettability on non-coated metallic surfaces has a broad range of engineering applications, yet achieving a rapid reverse of superwettability is still technically challenging on different metals. Here we show that rapid transition between superhydrophobicity (SHB) and superhydrophilicity (SHL) within tens of minutes can be achieved on femtosecond laser-treated Al and Ti surfaces with the assistance of ultraviolet (UV) irradiation and direct-current (DC) sputtering. The extremely high wettability conversion rate on metal surfaces was found to be related to the formation of textured amorphous metal oxides, whose relative content of oxygen vacancies (OVs) could be altered by UV irradiation and DC sputtering. Our findings provide a versatile approach for designing metal surfaces with rapidly reversible superwettability, enabling various applications such as oil-water separations and the controlled release of hydrophilic drugs. © 2024, The Authors. All rights reserved.

关键词： Femtosecond lasers

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