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arXiv 2023年

作者： Das, Suchandrima Sand, Andrea Hofmann, Felix Department of Mechanical Engineering University of Bristol Bristol United Kingdom Department of Applied Physics Aalto University Finland Department of Engineering Science University of Oxford Oxford United Kingdom

The interaction of edge dislocation with helium-implantation-induced defects in tungsten is investigated using molecular dynamics. Following prior investigations, we consider defects with two helium ions in a vacancy with a self-interstitial bound to it (He2V-SIA). Our observations suggest 3-10 He2V-SIA cluster together, with their pinning strength on glide dislocations increasing with size. For all cluster sizes, the dislocation bows around the cluster, until it gets unpinned, carrying the SIAs with it and leaving behind a helium-vacancy complex and newly created vacancies in its wake. The remnant helium-vacancy complex has little pinning effect, highlighting the "defect-clearing" process. A total solute hardening force for a distribution of clusters of different sizes, induced by 3000 appm of helium, is found to be ~700 MPa. This is in good agreement with the corresponding value of 750 MPa estimated in a previously developed crystal plasticity model simulating the deformation behaviour of the helium-implanted tungsten. © 2023, CC BY.

关键词： Molecular dynamics

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Robust Design of ATHENA ISM Parallel Manipulator 16th

Robust Design of ATHENA ISM Parallel Manipulator

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16th International Federation of Theory of Machines and Mechanisms World Congress, IFToMM WC 2023

作者： Múgica, Jorge Zubia, Joseba Illarramendi, M. Asunción Campo, Pablo Taubmann, Gonzalo Department of Electro-Mechanical Systems SENER Aerospace Avda. Zugazarte 56 Las Arenas48930 Spain Department of Communications Engineering UPV/EHU Ingeniero Torres Quevedo Plaza 1 Bilbao48013 Spain Department of Applied Physics UPV/EHU Ingeniero Torres Quevedo Plaza 1 Bilbao48013 Spain

ISBN: (纸本)9783031457692

Observational astrophysics in orbit requires a high accuracy in the pointing and positioning of optical systems as well as a high thermal stability. This work exposes the robust kinematic design process followed for the Instrument Selection Mechanism parallel manipulator for European Space Agency’s ATHENA X-ray observatory. The ISM is a parallel manipulator actuated with 6 rotatory actuators in charge of positioning ATHENA’s 3-m diameter mirror in 6 degrees of freedom. The main function of the ISM parallel manipulator is the focusing of the X-rays to each of the detectors the spacecraft carries in the focal plane. Each of the 6 rotary actuators used have a positioning error due to quantization and hysteresis. An interactive graphical method has been developed to minimize the errors on the 6 degrees of freedom of the mirror. This method obtains a set of geometrical parameters that characterize the mechanism. These parameters prevent the mechanism from blocking in all the range of motion and can provide the specified resolution even in the presence of a 10 K temperature increment in the mirror. The obtained mirror positioning and pointing accuracies are compliant with the requirements even in the worst-case scenario. The method developed permits fast iteration on the design to have a high adaptability to subsequent changes in the requirements along the project. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Kinematics

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The abundance and localization of environmental microplastics in gastrointestinal tract and muscle of Atlantic killifish (Fundulus heteroclitus): a pilot study

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Microplastics and Nanoplastics 2024年第1期4卷 23页

作者： Pitt, Jordan A. Gallager, Scott M. Youngs, Sarah Michel, Anna P. M. Hahn, Mark E. Aluru, Neelakanteswar Biology Department Woods Hole Oceanographic Institution Woods Hole 02543 MA United States Massachusetts Institute of Technology (MIT) – Woods Hole Oceanographic Institution (WHOI) Joint Graduate Program in Oceanography and Oceanographic Engineering Woods Hole 02543 MA United States CoastalOceanVision Inc 10 Edgerton Drive North Falmouth 02556 MA United States Department of Applied Ocean Physics and Engineering Woods Hole Oceanographic Institution Woods Hole 02543 MA United States

Microplastics (MPs) have been found in a diverse range of organisms across trophic levels. While a majority of the information on organismal exposure to plastics in the environment comes from gastrointestinal (GI) data, the prevalence of MP particles in other tissues is not well understood. Additionally, many studies have not been able to detect the smallest, most prevalent, MPs (1 µm – 5 mm) that are the most likely to distribute to tissues in the body. To address these knowledge gaps, MPs in the GI tract and muscle of Atlantic killifish (Fundulus heteroclitus) collected from two sites (Falmouth and Bourne) on Buzzards Bay, Cape Cod, MA were quantified down to 2 µm in size. Eight fish from Falmouth and 10 fish Bourne site were analyzed. Fourier-transform infrared spectroscopy and Raman spectroscopy were used to identify all particles. The mean concentrations of MPs in the GI tract and muscle from fish collected from Falmouth was 85.5 ± 70.2 and 11 ± 12.5 particles per gram wet weight, respectively. Fish collected from Bourne site had mean particle concentrations of 12.2 ± 18.1 and 1.69 ± 5.36 particles per gram wet weight. Of the 2,008 particles analyzed in various fish tissue samples, only 3.4% (69 particles) were identified as plastic;polymers included nylon, polyethylene, polypropylene, and polyurethane. MPs detected in the GI tract samples also tended to be more diverse in both size and polymer type than those found in the muscle. We found that MPs < 50 µm, which are often not analyzed in the literature, were the most common in both the GI tract and muscle samples. There was not a significant correlation between the MP content in the muscle compared to the GI tract, indicating that GI tract MP abundance cannot be used to predict non-GI tract tissue MP content;however, MP abundance in muscle correlated with fish total length, suggesting potential bioaccumulation of these small MPs. © The Author(s) 2024.

关键词： Bioaccumulation Fish Fourier-transform infrared spectroscopy Microplastics Raman spectroscopy Translocation

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Quantum Wrapper Networking: Investigating the Noise Impact of Classical Headers on the Quantum Payload

Quantum Wrapper Networking: Investigating the Noise Impact o...

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2024 Frontiers in Optics, FiO 2024

作者： Gül, Gamze On, Mehmet Berkay Tan, Shannon G. Proietti, Roberto Kanter, Gregory S. Yoo, S.J. Ben Kumar, Prem Graduate Program in Applied Physics Northwestern University 2145 Sheridan Road EvanstonIL60208 United States Department of Electrical and Computer Engineering University of California Davis DavisCA95616 United States Center for Photonic Communication and Computing Dept. of Electrical and Computer Eng. Northwestern University EvanstonIL60208 United States Department of Electronics and Telecommunications Engineering Politecnico di Torino Italy

We study the impact in time and frequency domains of classical headers on quantum payloads in quantum wrapper networking. We identify and characterize in-fiber scattering processes that produce noise photons degrading...

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An overview of the machinability of alloy steel

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Materials Today: Proceedings 2022年 62卷 3771-3781页

作者： Kumar Wagri, Naresh Petare, Anand Agrawal, Abhishek Rai, Ravi Malviya, Rajkumar Dohare, Sunil Kishore, Kamal Department of Applied Physics and Electronics Umeå University Umeå SE-90187 Sweden Central Workshop Indian Institute of Technology Indore Simrol 453552 MP India Department of Mechanical Engineering University Institute of Technology RGPV MP Bhopal 462033 India Energy Centre Maulana Azad National Institute of Technology MP Bhopal 462003 India Advanced Construction Engineering Research Centre Department of Civil Engineering GLA University Mathura 281406 India

Machinability is an important aspect for the machining of any materials. In general, it is controlled by means of tool life, surface roughness, power consumption, chip morphology, cutting forces, cutting fluid and material removal rate. Furthermore, it is also affected the microstructure, grain size, hardness, yield, tensile strength and chemical composition of the work piece material and tool materials. Advanced materials such as alloy steel, structural ceramics, and hardened steel are difficult to machine using conventional tool materials. The machining parameters such as depth of cut, cutting velocity and feed rate play a very important role to achieve high quality of surface finish on the machined surface. High interface temperatures at the tool tip and work piece material resulted poor surface finish and increases cutting forces and tool wear. A high cutting speeds with high feed and depth of cut causes high heat generation which reduces the tool substrates bonding strength resulting in accelerated tool wear and reducing tool life. In this article influence of heat treatment to enhance machinability alloy steel reviewed in terms of tool life, surface roughness, cutting forces and chip morphology. This article will be very useful for the students, research scholar and industrialist working in the area of machining. © 2022

关键词： Surface roughness

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Measuring kinetic inductance and superfluid stiffness of two-dimensional superconductors using high-quality transmission-line resonators

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Physical Review Research 2024年第4期6卷 043245-043245页

作者： Mary Kreidel Xuanjing Chu Jesse Balgley Abhinandan Antony Nishchhal Verma Julian Ingham Leonardo Ranzani Raquel Queiroz Robert M. Westervelt School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Department of Applied Physics and Applied Mathematics Columbia University New York New York 10027 USA Department of Mechanical Engineering Columbia University New York New York 10027 USA Department of Physics Columbia University New York New York 10027 USA RTX BBN Technologies Quantum Engineering and Computing Group Cambridge Massachusetts 02138 USA Center for Computational Quantum Physics Flatiron Institute New York New York 10010 USA Department of Physics Harvard University Cambridge Massachusetts 02138 USA

The discovery of van der Waals superconductors in recent years has generated a lot of excitement for their potentially novel pairing mechanisms. However, their typical atomic-scale thickness and micrometer-scale lateral dimensions impose severe challenges to investigations of pairing symmetry by conventional methods. We demonstrate an improved technique that employs high-quality-factor superconducting resonators to measure the kinetic inductance—up to one part per million—and loss of a van der Waals superconductor. We analyze the equivalent circuit model to extract the kinetic inductance, superfluid stiffness, penetration depth, and ratio of imaginary and real parts of the complex conductivity. We validate the technique by measuring aluminum and finding excellent agreement in both the zero-temperature superconducting gap as well as the complex conductivity data when compared with BCS theory. We then demonstrate the utility of the technique by measuring the kinetic inductance of multilayered niobium diselenide and discuss the limits to the accuracy of our technique when the transition temperature of the sample, NbSe2 at 7.06 K, approaches our Nb probe resonator at 8.59 K. Our method will be useful for practitioners in the growing fields of superconducting physics, materials science, and quantum sensing, as a means of characterizing superconducting circuit components and studying pairing mechanisms of the novel superconducting states which arise in layered two-dimensional materials and heterostructures.

关键词： Quantum circuits Superconducting order parameter Superconductivity 2-dimensional systems Van der Waals systems Methods in superconductivity Microwave techniques

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Control of skyrmion lattice order in the van der Waals ferromagnet Fe3GeTe2 16

Control of skyrmion lattice order in the van der Waals ferro...

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Spintronics XVI 2023

作者： Li, Yue McCray, Arthur R.C. Wang, Wei Basnet, Rabindra Pandey, Krishna Ma, Xuedan Hu, Jin Petford-Long, Amanda K. Phatak, Charudatta Materials Science Division Argonne National Laboratory LemontIL60439 United States Applied Physics Program Northwestern University EvanstonIL60208 United States Center for Nanoscale Materials Argonne National Laboratory LemontIL60439 United States Department of Physics University of Arkansas FayettevilleAR72701 United States Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States

ISBN: (纸本)9781510665262

Van der Waals ferromagnets are an intersting class of materials for exploring fundamental physics of magnetic order in the 2D limit as well as for technological applicaitons due to possibility of creating novel heterostructures. These materials have shown to host magnetic skyrmion lattices with their organization controlled by the magnetic properties such as anisotropy, exchange, and Dzyaloshinkii-Moriya interaction. For technological applications, it is also necessary to understand to the behavior of skyrmions in response to electric currents. In this work, we show the effect of electric current pulses on the magnetic skyrmions formed in Fe3GeTe2which has a Curie temperature of 220 K. We demonstrate via real-space in situ imaging using Lorentz transmission electron microscopy (LTEM) the effect of temperture and pulse width. © 2023 SPIE.

关键词： High resolution transmission electron microscopy

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Evaporation-Driven Cellular Patterns in Confined Hyperelastic Hydrogels

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Physical Review Letters 2023年第11期131卷 118202-118202页

作者： Baudouin Saintyves Romain Pic L. Mahadevan Irmgard Bischofberger Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA James Franck Institute and Department of Physics The University of Chicago Chicago Illinois 60637 USA John A. Paulson School of Engineering and Applied Sciences Department of Physics Department of Organismic and Evolutionary Biology Harvard University Cambridge Massachusetts 02138 USA

When a hyperelastic hydrogel confined between two parallel glass plates begins to dry from a lateral boundary, the volume lost by evaporation is accommodated by an inward displacement of the air-hydrogel interface that induces an elastic deformation of the hydrogel. Once a critical front displacement is reached, we observe intermittent fracture events initiated by a geometric instability resulting in localized bursts at the interface. These bursts relax the stresses and irreversibly form air cavities that lead to cellular networks. We show that the spatial extent of the strain field prior to a burst, influenced by the air-hydrogel interfacial tension and the confinement of the gel, determines the characteristic size of the cavities.

关键词： Elastic deformation Elasticity Evaporation Pattern formation Hydrogels

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Evidence of near-ambient superconductivity in a N-doped lutetium hydride

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Nature 2023年第7951期615卷 244-250页

作者： Nathan Dasenbrock-Gammon Elliot Snider Raymond McBride Hiranya Pasan Dylan Durkee Nugzari Khalvashi-Sutter Sasanka Munasinghe Sachith E Dissanayake Keith V Lawler Ashkan Salamat Ranga P Dias Department of Physics and Astronomy University of Rochester Rochester NY USA. Department of Mechanical Engineering School of Engineering and Applied Sciences University of Rochester Rochester NY USA. Unearthly Materials Inc. Rochester NY USA. Department of Physics and Astronomy University of Rochester Rochester NY USA. rdias@rochester.edu. Department of Mechanical Engineering School of Engineering and Applied Sciences University of Rochester Rochester NY USA. rdias@rochester.edu.

The absence of electrical resistance exhibited by superconducting materials would have enormous potential for applications if it existed at ambient temperature and pressure conditions. Despite decades of intense research efforts, such a state has yet to be realized. At ambient pressures, cuprates are the material class exhibiting superconductivity to the highest critical superconducting transition temperatures (T), up to about 133 K (refs. ). Over the past decade, high-pressure 'chemical precompression' of hydrogen-dominant alloys has led the search for high-temperature superconductivity, with demonstrated T approaching the freezing point of water in binary hydrides at megabar pressures. Ternary hydrogen-rich compounds, such as carbonaceous sulfur hydride, offer an even larger chemical space to potentially improve the properties of superconducting hydrides. Here we report evidence of superconductivity on a nitrogen-doped lutetium hydride with a maximum T of 294 K at 10 kbar, that is, superconductivity at room temperature and near-ambient pressures. The compound was synthesized under high-pressure high-temperature conditions and then-after full recoverability-its material and superconducting properties were examined along compression pathways. These include temperature-dependent resistance with and without an applied magnetic field, the magnetization (M) versus magnetic field (H) curve, a.c. and d.c. magnetic susceptibility, as well as heat-capacity measurements. X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and theoretical simulations provide some insight into the stoichiometry of the synthesized material. Nevertheless, further experiments and simulations are needed to determine the exact stoichiometry of hydrogen and nitrogen, and their respective atomistic positions, in a greater effort to further understand the superconducting state of the material.

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Negative thermal expansion and phase transition of low-temperature Mg_(2)NiH_(4)

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Journal of Magnesium and Alloys 2023年第9期11卷 3338-3349页

作者： Qun Luo Qi Cai Qinfen Gu Yu Shi Bin Liu Xuan Quy Tran Syo Matsumura Tong-Yi Zhang Kazuhiro Nogita Tao Lyu Qian Li Fusheng Pan State Key Laboratory of Advanced Special Steel&Shanghai Key Laboratory of Advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Materials Genome Institute Shanghai UniversityShanghai 200444China Australian Synchrotron ANSTO800 Blackburn RoadClaytonVictoria 3168Australia Department of Applied Quantum Physics and Nuclear Engineering Kyushu UniversityFukuoka 819-0395Japan Nihon Superior Centre for the Manufacture of Electronic Materials(NS CMEM) School of Mechanical and Mining EngineeringThe University of QueenslandBrisbaneQueensland 4072Australia National Engineering Research Center for Magnesium Alloy Chongqing UniversityChongqing 400044China

The negative thermal expansion(NTE) phenomenon is of great significance in fabricating zero thermal expansion(ZTE) materials to avoid thermal shock during heating and cooling. NTE is observed in limited groups of materials, e.g., metal cyanides, oxometallates, and metalorganic frameworks, but has not been reported in the family of metal hydrides. Herein, a colossal and continuous negative thermal expansion is firstly developed in the low-temperature phases of LT1-and LT2-Mg_(2)NiH_(4) between 488 K and 733 K from in-situ transmission electron microscope(TEM) video, with the volume contraction reaching 18.7% and 11.3%, respectively. The mechanisms for volume contraction of LT1 and LT2 phases are elucidated from the viewpoints of phase transformation, magnetic transition, and dehydrogenation, which is different from common NTE materials containing flexible polyhedra units in the structure. The linear volume shrinkage of LT2 in the temperature of 488-553 K corresponds to the phase transition of LT2→HT with a thermal expansion coefficient of -799.7 × 10^(-6) K^(-1) revealed by in-situ synchrotron powder X-ray diffraction. The sudden volume contraction in LT1 between 488 and 493 K may be caused by the rapid dehydrogenation of LT1 to Mg_(2)Ni. The revealed phenomenon in single composite material with different structures would be significant for preparing zero thermal expansion materials by tuning the fraction of LT1 and LT2 phases.

关键词： Negative thermal expansion Mg_(2)NiH_(4) Phase transformation In situ TEM In situ XRD

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