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arXiv 2023年

作者： Zhang, Hongmin Meng, Fanchao Meng, Haoyan Tong, Yang Liaw, Peter K. Yang, Xiao Zhao, Lei Wang, Haizhou Gao, Yanfei Chen, Shuying Institute for Advanced Studies in Precision Materials Yantai University Shandong Yantai264005 China Department of Materials Science and Engineering The University of Tennessee KnoxvilleTN37996 United States Key Laboratory of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing100190 China Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Key Laboratory of Metal Materials Characterization Central Iron and Steel Research Institute Beijing100081 China

The present work reported a novel L12-strengthening NiCoCrAlTi high entropy alloy (HEA) with an outstanding synergy of tensile strength and ductility at both ambient and high temperatures. Transmission electron microscopy (TEM) characterization revealed a high density of rod-like and spheroidal L12 precipitates distributing in the micro/nanograins and non-recrystallized regions in the annealed specimens. The tremendously high yield stress, ultimate tensile stress (UTS), and ductility of the HEA at 600 °C were ~1060 MPa, 1271 MPa, and 25%, respectively, which were significantly superior to most reported HEAs and Co- and Ni-based superalloys to date. Systematic TEM analysis unveiled that the cooperation among L12 precipitation, extensive stacking faults (SFs), deformation twins (DTs), immobile Lomer-Cottrell (L-C) locks formed from interactions between SFs and SFs/DTs, hierarchical SFs/DTs networks, as well as hetero-deformation-induced strengthening dominated the plastic deformation at 600 °C. Such a unique deformation mechanism enabled extremely high tensile strength and sustained ductility of the HEA at a high temperature. © 2023, CC BY-NC-ND.

关键词： Stacking faults

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Possible Kondo Physics near a Metal-Insulator Crossover in the A-Site Ordered Perovskite CaCu3Ir4O12

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Physical Review Letters 2013年第17期111卷 176403-176403页

作者： J.-G. Cheng J.-S. Zhou Y.-F Yang H. D. Zhou K. Matsubayashi Y. Uwatoko A. MacDonald J. B. Goodenough Materials Science and Engineering Program and Texas Materials Institute University of Texas at Austin Austin Texas 78712 USA Institute for Solid State Physics University of Tokyo Kashiwa 277-8581 Japan Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996 USA Department of Physics and Texas Materials Institute University of Texas at Austin Austin Texas 78712 USA

The A-site ordered perovskite (AA3′)B4O12 can accommodate transition metals on both A′ and B sites in the crystal structure. Because of this structural feature, it is possible to have narrow-band electrons interacting with broadband electrons from different sublattices. Here we report a new A-site ordered perovskite (CaCu3)Ir4O12 synthesized under high pressure. The coupling between localized spins on Cu2+ and itinerant electrons from the Ir-O sublattice makes Kondo-like physics take place at a temperature as high as 80 K. Results from the local density approximation calculation have confirmed the relevant band structure. The magnetization anomaly found at 80 K can be well rationalized by the two-fluid model.

关键词： METAL insulator semiconductors PEROVSKITE TRANSITION metals CRYSTAL structure ELECTRONS MAGNETIZATION

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Integrated Semiconductor Optical Sensors for Chronic, Minimally-Invasive Imaging of Brain Function

Integrated Semiconductor Optical Sensors for Chronic, Minima...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Thomas T. Lee Ofer Levi Jianhua Cang Megumi Kaneko Michael P. Stryker Stephen J Smith Krishna V. Shenoy James S. Harris Department of Electrical Engineering University of Stanford Stanford CA USA Departments of Electrical Engineering and Applied Physics University of Stanford Stanford CA USA Department of Physiology University of California San Francisco USA Department of Molecular and Cellular Physiology and the Neurosciences Program University of Stanford Stanford CA USA Department of Electrical Engineering and the NeurosciencesProgram University of Stanford Stanford CA USA Departments of Electrical Engineering Applied Physics and Materials Science and Engineering University of Stanford Stanford CA USA

Intrinsic optical signal (IOS) imaging is a widely accepted technique for imaging brain activity. We propose an integrated device consisting of interleaved arrays of gallium arsenide (GaAs) based semiconductor light sources and detectors operating at telecommunications wavelengths in the near-infrared. Such a device will allow for long-term, minimally invasive monitoring of neural activity in freely behaving subjects, and will enable the use of structured illumination patterns to improve system performance. In this work we describe the proposed system and show that near-infrared IOS imaging at wavelengths compatible with semiconductor devices can produce physiologically significant images in mice, even through skull

关键词： Optical sensors Optical imaging Gallium arsenide Brain Optical arrays Sensor arrays Light sources Minimally invasive surgery Monitoring Lighting

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Unnecessary risks created by uncontrolled rocket reentries

arXiv

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arXiv 2022年

作者： Byers, Michael Wright, Ewan Boley, Aaron Byers, Cameron Department of Political Science University of British Columbia VancouverBC Canada Interdisciplinary Studies Graduate Program University of British Columbia VancouverBC Canada Department of Physics and Astronomy University of British Columbia VancouverBC Canada Bachelor of Engineering Program University of Victoria VictoriaBC Canada

In 2020, over 60% of launches to low Earth orbit resulted in one or more rocket bodies being abandoned in orbit and eventually returning to Earth in an uncontrolled manner. When they do so, between 20 and 40% of their mass survives the heat of atmospheric reentry. Many of the surviving pieces are heavy enough to pose serious risks to people, on land, at sea, and in airplanes. There is no international consensus on the acceptable level of risk from reentering space objects. This is sometimes a point of contention, such as when a 20 tonne Long March 5B core stage made an uncontrolled reentry in May 2021. Some regulators, including the US, France, and ESA, have implemented a 1 in 10, 000 acceptable casualty risk (i.e., statistical threat to human life) threshold from reentering space objects. We argue that this threshold ignores the cumulative effect of the rapidly increasing number of rocket launches. It also fails to address low risk, high consequence outcomes, such as a rocket stage crashing into a high-density city or a large passenger aircraft. In the latter case, even a small piece could cause hundreds of casualties. Compounding this, the threshold is frequently ignored or waived when the costs of adherence are deemed excessive. We analyse the rocket bodies that reentered the atmosphere from 1992-2021 and model the associated cumulative casualty expectation. We then extrapolate this trend into the near future (2022-2032), modelling the potential risk to the global population from uncontrolled rocket body reentries. We also analyse the population of rocket bodies that are currently in orbit and expected to deorbit soon, and find that the risk distribution is significantly weighted to latitudes close to the equator. This represents a disproportionate burden of casualty risk imposed on the countries of the Global South by major spacefaring countries. Modern rockets have reignitable engines, allowing controlled reentries into remote areas of the oceans. This, combine

关键词： Rockets

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Bioethanol Production from Microalgae Biomass at High Solid Loadings

SSRN

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SSRN 2022年

作者： Condor, Billriz E. de Luna, Mark Daniel G. Chang, Yu-Han Chen, Jih-Heng Leong, Yoong Kit Chen, Po-Ting Chen, Chun-Yen Lee, Duu-Jong Chang, Jo-Shu Energy Engineering Program National Graduate School of Engineering University of the Philippines Diliman Quezon City1101 Philippines Department of Chemical Engineering College of Engineering University of the Philippines Diliman Quezon City 1101 Philippines Department of Chemical Engineering National Cheng Kung University Tainan701 Taiwan Research Center for Smart Sustainable Circular Economy Tunghai University Taichung Taiwan Department of Chemical and Materials Engineering Tunghai University Taichung Taiwan Department of Biotechnology and Food Technology Southern Taiwan University of Science and Technology Tainan71005 Taiwan University Center for Bioscience and Biotechnology National Cheng Kung University Tainan701 Taiwan Department of Mechanical Engineering City University of Hong Kong Kowloon Tang Hong Kong Department of Chemical Engineering and Materials Science Yuan Ze University Chung-Li32003 Taiwan

Industrial adoption of microalgae biofuel technology has always been hindered by its economic viability. To increase the feasibility of bioethanol production from microalgae, fermentation was applied to Chlorella vulgaris FSP-E biomass at high-solid-loading conditions. First, Chlorella vulgaris FSP-E was cultivated to produce microalgae biomass with high carbohydrate content. Next, different ethanol-producing microorganisms were screened. Saccharomyces cerevisiae FAY-1 showed no inhibition when fermenting high initial glucose concentrations and was selected for the fermentation experiments at high solids loading. Optimization of acid hydrolysis at high biomass loading was also performed. The fermentation of microalgal biomass hydrolysate produced a final ethanol concentration and yield higher than most reported literature using microalgae feedstock. In addition, the kinetics of bioethanol fermentation of microalgae hydrolysate under high solid loading were evaluated. These results show the potential of fermenting microalgae biomass at high solids loading in improving the viability of microalgae bioethanol production. © 2022, The Authors. All rights reserved.

关键词： Microalgae

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Reconfigurable on-chip photoconductive switches

arXiv

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arXiv 2019年

作者： Fang, Cheng-Yi Lin, Hung-Hsi Alouini, Mehdi Fainman, Yeshaiahu Amili, Abdelkrim El University of California San Diego Materials Science & Engineering Program La JollaCA92093 United States University of California San Diego Department of Electrical & Computer Engineering La JollaCA92093 United States Institut FOTON University of Rennes 1 CNRS Campus de Beaulieu Rennes France

Microwave photonics uses light to carry and process microwave signals over a photonic link. However, light can instead be used as a stimulus to microwave devices that directly control microwave signals. Such optically controlled amplitude and phase-shift switches are investigated for use in reconfigurable microwave systems, but they suffer from large footprint, high optical power level required for switching, lack of scalability and complex integration requirements, restricting their implementation in practical microwave systems. Here, we report Monolithic Optically Reconfigurable Integrated Microwave Switches (MORIMSs) built on a CMOS compatible silicon photonic chip that addresses all of the stringent requirements. Our scalable micrometer-scale switches provide higher switching efficiency and require optical power orders of magnitude lower than the state-of-the-art. Also, it opens a new research direction on silicon photonic platforms integrating microwave circuitry. This work has important implications in reconfigurable microwave and millimeter wave devices for future communication networks. Copyright © 2019, The Authors. All rights reserved.

关键词： Silicon photonics

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Machine learning moment tensor potential for modeling dislocation and fracture in L10−TiAl and D019−Ti3Al alloys

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Physical Review materials 2023年第10期7卷 103602-103602页

作者： Ji Qi Z. H. Aitken Qingxiang Pei Anne Marie Z. Tan Yunxing Zuo M. H. Jhon S. S. Quek T. Wen Zhaoxuan Wu Shyue Ping Ong Materials Science and Engineering Program University of California San Diego 9500 Gilman Dr Mail Code 0448 La Jolla California 92093-0448 USA Institute of High Performance Computing (IHPC) Agency for Science Technology and Research (A*STAR) 1 Fusionopolis Way Connexis #16-16 Singapore 138632 Republic of Singapore Department of NanoEngineering University of California San Diego 9500 Gilman Dr Mail Code 0448 La Jolla California 92093-0448 USA Department of Mechanical Engineering The University of Hong Kong Hong Kong SAR China Department of Materials Science and Engineering City University of Hong Kong Hong Kong SAR China Hong Kong Institute for Advanced Study City University of Hong Kong Hong Kong SAR China

Dual-phase γ-TiAl and α2−Ti3Al alloys exhibit high strength and creep resistance at high temperatures. However, they suffer from low tensile ductility and fracture toughness at room temperature. Experimental studies show unusual plastic behavior associated with ordinary and superdislocations, making it necessary to gain a detailed understanding on their core properties in individual phases and at the two-phase interfaces. Unfortunately, extended superdislocation cores are widely dissociated beyond the length scales practical for routine first-principles density-functional theory (DFT) calculations, while extant interatomic potentials are not quantitatively accurate to reveal mechanistic origins of the unusual core-related behavior in either phases. Here, we develop a highly accurate moment tensor potential (MTP) for the binary Ti-Al alloy system using a DFT dataset covering a broad range of intermetallic and solid solution structures. The optimized MTP is rigorously benchmarked against both previous and new DFT calculations, and unlike existing potentials, is shown to possess outstanding accuracy in nearly all tested mechanical properties, including lattice parameters, elastic constants, surface energies, and generalized stacking fault energies (GSFE) in both phases. The utility of the MTP is further demonstrated by producing dislocation core structures largely consistent with expectations from DFT-GSFE and experimental observations. The new MTP opens the path to realistic modeling and simulations of bulk lattice and defect properties relevant to the plastic deformation and fracture processes in γ-TiAl and α2−Ti3Al dual-phase alloys.

关键词： Interatomic & molecular potentials Alloys Machine learning

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Characterization of the Root Surface of a Friction Stir Welded Uns S32760 Super Duplex Stainless Steel: Insights into its Microstructure and Corrosion Resistance

SSRN

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SSRN 2023年

作者： Vacchi, G.S. de Carvalho, Willian S. Meinhardt, C.P. Bergmann, Luciano A. Amancio-Filho, Sergio T. Rovere, C.A.D. Munir Rachid Corrosion Laboratory Department of Materials Engineering Federal University of São Carlos Rodovia Washington Luis Km 235 SP São Carlos13565-905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering Brazil Graz University of Technology – TU Graz Institute of Materials Science Joining and Forming BMK Endowed Professorship for Aviation Kopernikusgasse 24/1 Graz8010 Austria Federal University of Pampa Department of Mechanical Engineering Avenida Tiarajú 810 RS Alegrete Brazil Helmholtz-Zentrum Hereon Institute of Materials Mechanics Solid State Materials Processing Max-Planck-Straße 1 Geesthacht Germany

The root surface of a friction stir welded super duplex stainless steel (UNS S32760) was thoroughly characterized in this study. The findings revealed a refined grain structure and a conspicuous increase of 50 HV0.3 in the Root's hardness. Interestingly, the volume fraction of the ferrite phase remained largely unchanged. Rapid cooling in the welding process led to the Cr2N precipitation at the ferrite/ferrite grain boundaries in the root area, significantly increasing sensitization, reducing localized corrosion resistance under high potentials in a neutral pH saline environment, and adversely affecting root passivity in a hydrochloric acid environment compared to the base metal. © 2023, The Authors. All rights reserved.

关键词： Friction stir welding

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All-dielectric metasurfaces

All-dielectric metasurfaces

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Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim)

作者： Yuanmu Yang Parikshit Moitra Ivan. I. Kravchenko Daryl. P. Briggs Jason Valentine Interdisciplinary Materials Science Program Vanderbilt University Nashville Tennessee USA Oak Ridge National Laboratory Oak Ridge TN US Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak Ridge Tennessee USA Department of Mechanical Engineering Vanderbilt University Nashville Tennessee USA

In this talk, I will discuss our recent efforts to develop purely dielectric metamaterials possessing low absorption loss at optical frequencies. I will discuss implementations ranging from wavefront control to high Q... 详细信息

ISBN: (纸本)9781467371100

关键词： Optical resonators Dielectrics Optical variables control Absorption Optical losses Optical vortices Optical reflection

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Comparison of PM-HIP to Forged SA508 Pressure Vessel Steel Under High-Dose Neutron Irradiation

arXiv

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arXiv 2023年

作者： Jiang, Wen Zhao, Yangyang Lu, Yu Wu, Yaqiao Frazer, David Guillen, Donna P. Gandy, David W. Wharry, Janelle P. School of Materials Engineering Purdue University West LafayetteIN United States Micron School of Materials Science & Engineering Boise State University BoiseID United States Center for Advanced Energy Studies Idaho FallsID United States Idaho National Laboratory Idaho FallsID United States Electric Power Research Institute CharlotteNC United States

Powder metallurgy with hot isostatic pressing (PM-HIP) is an advanced manufacturing process that is envisioned to replace forging for heavy nuclear components, including the reactor pressure vessel (RPV). But PM-HIP products must at least demonstrate comparable irradiation tolerance than forgings in order to be qualified for nuclear applications. The objective of this study is to directly compare PM-HIP to forged SA508 Grade 3 Class 1 low-alloy RPV steel at two neutron irradiation conditions: ~0.5-1.0 displacements per atom (dpa) at ~270ºC and ~370ºC. PM-HIP SA508 experiences greater irradiation hardening and embrittlement (total elongation) than forged SA508. However, uniform elongation and approximate toughness are comparable across all irradiated materials, suggesting irradiated PM-HIP SA508 exhibits superior ductility at maximum load-bearing capacity. The irradiation hardening mechanism is linked to composition rather than fabrication method. Since PM-HIP SA508 has higher Mn and Ni concentration, it is more susceptible to irradiation-induced nucleation of Mn-Ni-Si-P (MNSP) nanoprecipitates and dislocation loops, which both contribute to hardening. Conversely, the forged material nucleates fewer MNSPs, causing dislocation loops to control irradiation hardening. These results show promise for the irradiation performance of PM-HIP SA508 and can motivate future nuclear code qualification of PM-HIP fabrication for RPVs. © 2023, CC BY-NC-ND.

关键词： Neutron irradiation

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