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arXiv 2024年

作者： Guo, Yucheng Wang, Zehao Xie, Fang Huang, Yuefei Gao, Bin Oh, Ji Seop Wu, Han Liu, Zhaoyu Ren, Zheng Fang, Yuan Biswas, Ananya Zhang, Yichen Yue, Ziqin Hu, Cheng Jozwiak, Chris Bostwick, Aaron Rotenberg, Eli Hashimoto, Makoto Lu, Donghui Kono, Junichiro Chu, Jiun-Haw Yakobson, Boris I. Birgeneau, Robert J. Si, Qimiao Dai, Pengcheng Yi, Ming Department of Physics and Astronomy Rice University HoustonTX77005 United States Advanced Light Source Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States Department of Physics University of California BerkeleyCA94720 United States Department of Physics University of Washington Washington98105 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo ParkCA94025 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States

In the quest for novel quantum states driven by topology and correlation, kagome lattice materials have garnered significant interest due to their distinctive electronic band structures, featuring flat bands (FBs) arising from the quantum destructive interference of the electronic wave function. The tuning of the FBs to the chemical potential would lead to the possibility of liberating electronic instabilities that lead to emergent electronic orders. Despite extensive studies, direct evidence of FBs tuned to the chemical potential and their participation in emergent electronic orders have been lacking in bulk quantum materials. Here using a combination of Angle-Resolved Photoemission Spectroscopy (ARPES) and Density Functional Theory (DFT), we reveal that the low-energy electronic structure of the recently discovered Cr-based kagome metal superconductor CsCr3Sb5 is dominated by a pervasive FB in close proximity to, and below the Fermi level. A comparative analysis with orbital-projected DFT and polarization dependence measurement uncovers that an orbital-selective renormalization mechanism is needed to reconcile the discrepancy with the DFT calculations, which predict the FB to appear 200 meV above the Fermi level. Furthermore, we observe the FB to shift away from the Fermi level by 20 meV in the low-temperature density wave-ordered phase, highlighting the role of the FB in the emergent electronic order. Our results reveal CsCr3Sb5 to stand out as a promising platform for further exploration into the effects of FBs near the Fermi level on kagome lattices, and their role in emergent orders in bulk quantum materials. © 2024, CC BY.

关键词： Density functional theory

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Diversification of the Carbodicarbene Class by Embedding an Anionic Component in its Scaffold

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Chemistry - A European Journal 2023年第71期29卷 e202302886页

作者： Yu, Cheng-Han Au-Yeung, Ka-Chun Liu, Ruiqin Lee, Chao-Hsien Jiang, Dandan Semagne Aweke, Bamlaku Wu, Chia-Hung Wang, Yu-Jou Wang, Ting-Hsuan Voon Kong, Kien Yap, Glenn P. A. Chen, Wen-Ching Frenking, Gernot Zhao, Lili Ong, Tiow-Gan Institute of chemistry Academia Sinica Taipei115201 Taiwan School of Chemistry and Molecular Engineering State Key Laboratory of Materials-Oriented Chemical Engineering Nanjing Tech University Nanjing China Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Strasse MarburgD-35043 Germany Department of Chemistry and Biochemistry University of Delaware NewarkDE United States Department of Chemistry National Taiwan University Taipei Taiwan Department of Applied Chemistry National Yang Ming Chiao Tung University Hsinchu Taiwan Sustainable Chemical Science and Technology Taiwan International Graduate Program Academia Sinica Taipei Taiwan Corporate R&D Center LCY Chemical Corporation Kaohsiung Taiwan Department of Medicinal and Applied Chemistry Kaohsiung Medical University Kaohsiung Taiwan

Carbodicarbene (CDC) has become an emerging ligand in many fields due to its strong σ-donating ability. 2- moiety within the framework to leverage the electronic feature of carbon carbone. The elucidation of X-ray crystal structures, ligand competition as well as transmetallation experiments suggest that the anionic moiety has enhanced the overall donor strength of the traditional neutral CDC. Importantly, this anionic scaffold exhibits a facile second coordination toward Au(I), Ag(I) and Pd(II) without any external ligand assistance, whereas previously reported neutral pincer CDC complexes do not possess a two-fold donor capacity. The analysis of the bonding situation via theoretical methods shows that the description of the anionic CDC moieties in terms of dative bonding is preferred over the model of delocalized positive charge, as it accounts for the two-fold donor ability of the divalent carbon atom, preserving a characteristic feature of a carbone. © 2023 Wiley-VCH GmbH.

关键词： Scaffolds

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Numerical and experimental investigation on the residual stresses generated by scanning induction hardening

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Procedia CIRP 2022年 108卷 827-832页

作者： Maialen Areitioaurtena Unai Segurajauregi Martin Fisk Mario J. Cabello Eneko Ukar Ikerlan Technology Research Centre Basque Research and Technology Alliance (BRTA). Paseo J.M. Arizmendiarrieta 2 20500 Arrasate-Mondragon Spain Department of Materials Science and Applied Mathematics. Malmö University Malmö Sweden Division of Solid Mechanics Lund University P.O. Box 118 SE-221 00 Lund Sweden Department of Mechanical Engineering University of the Basque Country Alameda Urquijo s/n 48013 Bilbao Spain

Induction hardening is widely used in the industry as a surface heat treatment that improves the surface and the subsurface hardness of components greatly. The hardened case, which usually is a few mm, highly impacts the surface and structural integrity of the component. In this work, we simulate the scanning induction hardening process by means of finite element modeling. The computed hardness, microstructure, and residual stress profile are compared with experimentally measured data using several surface and subsurface characterization techniques. A very good agreement is found between the simulated and experimentally measured residual stresses, which were characterized by the incremental hole drilling technique.

关键词： Induction hardening residual stresses numerical simulation

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Enhanced Superconducting Qubit Performance Through Ammonium Fluoride Etch

arXiv

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arXiv 2024年

作者： Kopas, Cameron J. Goronzy, Dominic P. Pham, Thang Torres Castanedo, Carlos G. Cheng, Matthew Cochrane, Rory Nast, Patrick Lachman, Ella Zhelev, Nikolay Z. Vallières, André Murthy, Akshay A. Oh, Jin-Su Zhou, Lin Kramer, Matthew J. Cansizoglu, Hilal Bedzyk, Michael J. Dravid, Vinayak P. Romanenko, Alexander Grassellino, Anna Mutus, Josh Y. Hersam, Mark C. Yadavalli, Kameshwar Rigetti Computing BerkeleyCA United States Department of Materials Science and Engineering Northwestern University EvanstonIL United States Center for Applied Physics and Superconducting Technologies Northwestern University EvanstonIL United States Department of Physics and Astronomy Northwestern University EvanstonIL United States Department of Physics University of Oregon EugeneOR United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Fermi National Accelerator Laboratory BataviaIL United States Ames Laboratory U.S. Department of Energy AmesIA United States Northwestern University EvanstonIL United States Department of Chemistry Northwestern University EvanstonIL United States Department of Electrical and Computer Engineering Northwestern University EvanstonIL United States

The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. The dominant sources of these losses are believed to originate from amorphous materials and defects at interfaces and surfaces, likely as a result of fabrication processes or ambient exposure. Here, we explore a novel wet chemical surface treatment at the Josephson junction-substrate and the substrate-air interfaces by replacing a buffered oxide etch (BOE) cleaning process with one that uses hydrofluoric acid followed by aqueous ammonium fluoride. We show that the ammonium fluoride etch process results in a statistically significant improvement in median T1 by ∼ 22% (p = 0.002), and a reduction in the number of strongly-coupled TLS in the tunable frequency range. Microwave resonator measurements on samples treated with the ammonium fluoride etch prior to niobium deposition also show ∼ 33% lower TLS-induced loss tangent compared to the BOE treated samples. As the chemical treatment primarily modifies the Josephson junction-substrate interface and substrate-air interface, we perform targeted chemical and structural characterizations to examine materials’ differences at these interfaces and identify multiple microscopic changes that could contribute to decreased TLS. © 2024, CC BY-NC-ND.

关键词： Fluorine compounds

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Gas sensor array to classify the chicken meat with E. coli contaminant by using random forest and support vector machine

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Biosensors and Bioelectronics: X 2021年 9卷

作者： Astuti, Suryani Dyah Tamimi, Mohammad H. Pradhana, Anak A.S. Alamsyah, Kartika A. Purnobasuki, Hery Khasanah, Miratul Susilo, Yunus Triyana, Kuwat Kashif, Muhammad Syahrom, Ardiyansyah Department of Physics Faculty of Science and Technology Universitas Airlangga Surabaya60115 Indonesia Biomedical Engineering Magister Program Faculty of Science and Technology Universitas Airlangga Surabaya60115 Indonesia Department of Biology Faculty of Science and Technology Universitas Airlangga Surabaya60115 Indonesia Department of Chemistry Faculty of Science and Technology Universitas Airlangga Surabaya60115 Indonesia Faculty of Engineering-Universitas Dr Soetomo Indonesia Surabaya60118 Indonesia Department of Physics Faculty of Matematic and Natural Science Universitas Gadjah Mada Yogyakarta Indonesia Department of Applied Mechanics and Design Faculty of Mechanical Engineering Universiti Teknologi Malaysia Johor Bahru81310 Malaysia

Microbes such as Escherichia coli (E. coli) can easily contaminate raw chicken meat in clean conditions, causing decay and unpleasant scents. This study aims to characterize gas patterns by comparing fresh chicken meat and E. coli bacteria contaminated chicken meat based on shelf life using a Gas Sensor Array (GSA) system (MQ2, MQ3, MQ7, MQ8, MQ135, and MQ136) on electronic nose. The findings revealed GSA capability to detect a variety of typical gas patterns formed by the samples. This gas detection property is indicated by the appearance of the variance in the sensors output voltage pattern for each sample variation. The data for fresh and contaminated samples were classified by the random forest (RF) classifier with 99.25% and 98.42% precision, respectively. Furthermore, the support vector machine (SVM) classifier correctly identified the fresh and contaminated samples with 98.61% and 86.66% accuracy, respectively. This finding offers insight for GSA capability in classifying chicken meat contaminated with E. coli using an RF and SVM. © 2021 The Author(s)

关键词： Support vector machines

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A Tendon-Driven Origami Hopper Triggered by Proprioceptive Contact Detection

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

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IEEE International Conference on Soft Robotics (RoboSoft)

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

ISBN: (数字)9781728165707

ISBN: (纸本)9781728165714

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.

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Unique material modifications of Ga2O3 enabled by ultrafast laser irradiation 11

Unique material modifications of Ga2O3 enabled by ultrafast ...

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Oxide-based materials and Devices XI 2020

作者： Ahn, Minhyung Sarracino, Alex Ansari, Abdul Torralva, Ben Yalisove, Steven Phillips, Jamie Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Climate and Space Sciences and Engineering University of Michigan Ann ArborMI48109 United States Materials Science and Engineering Department University of Michigan Ann ArborMI48109 United States

ISBN: (纸本)9781510633254

Ultrafast (femtosecond pulse) laser irradiation provides unique laser-material interactions associated with high instantaneous electric fields and short timescales that lead to a nonequilibrium state between excited electrons and phonons. These interactions result in material modifications that differ from conventional chemical, physical, and thermal processing at much longer timescales, and an opportunity to address material and device processing challenges associated with wide-bandgap materials such as Ga2O3. In this work, we explore ultrafast laser irradiation (Ti:sapphire, 150 fs pulse width) of bulk (010) Sn-doped β-Ga2O3 under two different wavelengths, fundamental (780 nm) and frequency-doubled (390 nm), and a range of laser fluences. We identified a regime for laser-induced damage threshold resulting in material ablation, thermally-induced straight crack formation, and recrystallization. Rastering on a β-Ga2O3 substrate created surface nanostructures including laser-induced periodic surface structures at a high spatial frequency (period ∼250 nm). These highly aligned periodic structures can be controlled by laser polarization and wavelength, presenting a means for direct writing of surface nanostructures. Enhanced atomic movement associated with a transient metallic state can provide a means for intentional generation of point defects via the laser irradiation. These point defects may offer a means of electrical modification, which was demonstrated as more than five orders of the magnitude enhancement of lateral conductance on rastered β-Ga2O3. Moreover, a hydrophobic surface of β-Ga2O3was achieved by ultrafast laser irradiation. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Hydrophobicity

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Landau Polaritons in a Full-Dielectric Three-Dimensional Photonic-Crystal Cavity

Landau Polaritons in a Full-Dielectric Three-Dimensional Pho...

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CLEO: science and Innovations, S and I 2022

作者： Tay, Fuyang Mojibpour, Ali Liang, Shuang Baydin, Andrey Ahmadivand, Arash Peraca, Nicolas Marquez Xu, Hongjing Gardner, Geoff C. Manfra, Michael J. Hagenmüller, David Kono, Junichiro Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States Birck Nanotechnology Center Purdue University West LafayetteIN47907 United States Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Microsoft Quantum Purdue Purdue University West LafayetteIN47907 United States School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States School of Materials Engineering Purdue University West LafayetteIN47907 United States Université de Strasbourg CNRS Strasbourg67000 France Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States

ISBN: (纸本)9781557528209

We fabricated a full-dielectric three-dimensional photonic-crystal cavity containing an ultrahigh-mobility two-dimensional electron gas. By applying a strong perpendicular magnetic field, we created Landau polaritons originating from the ultrastrong coupling of electrons with cavity modes. © Optica Publishing Group 2022, © 2022 The Author(s)

关键词： Polariton

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Unveiling a new shear stress transfer mechanism in composites with helically wound hierarchical fibres

arXiv

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arXiv 2021年

作者： Cutolo, A. Carotenuto, A.R. Palumbo, S. Bosia, F. Pugno, N. Fraldi, M. Department of Structures for Engineering and Architecture University of Napoli Federico II Italy Department of Applied Science and Technology Politecnico di Torino Italy Laboratory of Bio-inspired Bionic Nano MetaMaterials & Mechanics Department of Civil Environmental and Mechanical Engineering University of Trento Italy Griffith Theory Centenary Lab School of Engineering and Materials Science Queen Mary University of London United Kingdom

The mechanical performance of reinforced composites is strongly influenced at different scales by the stress transferred at the matrix-fibre interfaces and at any surface where material discontinuity occurs. In particular, the mechanical response of elastomeric composites where the reinforcement is composed by cords with helically wound fibres is heavily compromised by fatigue and delamination phenomena occurring at cord-rubber as well as at the ply interfaces, since rubber and polymeric matrices are mainly vulnerable to the accumulation of deviatoric energy due to the shear stresses transferred across the surfaces. Despite the large diffusion of composites in a vast field of applications and the mature knowledge of their behaviour, some key mechanical aspects underlying failure mechanisms are still partially unclear. For example, stress amplification and strain localization are often difficult to predict by means of analytical solutions and averaging techniques that usually conceal stress gradients. In this work, we analyse coupling between torsional and tensile loads in twisted cords, which are adopted in many cases to reinforce composites and rubbers in tire applications. We provide a model characterized by an enriched cord-matrix mechanical interplay able to theoretically explain and predict actual stress distributions responsible for the onset of delamination and fatigue-guided phenomena that are experimentally observed in these composites. In particular, we demonstrate that the assumption of a monoclinic/trigonal behaviour for the mechanical response of the hierarchical strands allows to estimate, by means of analytical formulas and a homogenization approach, hitherto neglected shear stresses at the matrix-reinforcement interface. These stresses are transferred to the neighbouring regions, leading to post-elastic behaviour and failure events. Finite Element results for rubber/cord composites under various boundary conditions highlight the discrepancies in mech

关键词： Shear stress

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Emerging contact force heterogeneity in ordered soft granular media

arXiv

引用

arXiv 2021年

作者： Li, Liuchi Karapiperis, Konstantinos Andrade, José E. Earth and Environmental Science Area Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Mechanics & Materials Lab Department of Mechanical and Process Engineering ETH Zürich Zürich8092 Switzerland Division of Engineering and Applied Science California Institute of Technology PasadenaCA91125 United States

Under external perturbations, inter-particle forces in disordered granular media are well known to form a heterogeneous distribution with filamentary patterns. Better understanding these forces and the distribution is important for predicting the collective behavior of granular media, the media second only to water as the most manipulated material in global industry. However, studies in this regard so far have been largely confined to granular media exhibiting only geometric heterogeneity, leaving the dimension of mechanical heterogeneity a rather uncharted area. Here, through a FEM contact mechanics model, we show that a heterogeneous interparticle force distribution can also emerge from the dimension of mechanical heterogeneity alone. Specifically, we numerically study inter-particle forces in packing of mechanically heterogeneous disks arranged over either a square or a hexagonal lattice and under quasi-static isotropic compression. Our results show that, at the system scale, a hexagonal packing exhibit a more heterogeneous inter-particle force distribution than a square packing does;At the particle scale, for both packing lattices, preliminary analysis shows the consistent coexistence of outliers (i.e., softer disks sustaining larger forces while stiffer disks sustaining smaller forces) in comparison to their homogeneous counterparts, which implies the existence of nonlocal effect. Further analysis on the portion of outliers and on spatial contact force correlations suggest that the hexagonal packing shows more pronounced nonlocal effect over the square packing under small mechanical heterogeneity. However, such trend is reversed when assemblies becomes more mechanically heterogeneous. Lastly, we confirm that, in the absence of particle reorganization events, contact friction merely plays the role of packing stabilization while its variation has little effect on inter-particle forces and their distribution. © 2021, CC BY.

关键词： Deformation

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