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SSRN 2023年

作者： Pimentel, Dyvison Pedreira Campinas São Paulo13083-859 Brazil Federal Institute of Maranhão IFMA-PPGEM Avenida Getúlio Vargas 4 MA São LuísCEP 65030-005 Brazil PPGCM-Materials Science and Engineering Graduate Program UFPI-Federal University of Piaui PI Teresina64049-550 Brazil

In this work magnetization measurements in oxidized CuCl are presented. Two magnetic transitions are clearly observed, one around 6.4 K and the other around 18 K. Such magnetic transitions are closely related to Clinoatacamite Cu2Cl(OH)3. Interestingly, another transition is observed at 16 K which is also very difficult to know its origin. The apparent "diamagnetism" observed in the ZFC measurements is due to the exchange bias effect, leading to the conclusion that our CuCl samples are in a highly frustrated state due to the presence of clinoatacamite. X-ray diffractograms at different time intervals of exposure to air of the virgin CuCl sample to determine the appearance of new phases in the material composition were carried out. The results obtained show us that an exposure prolonged exposure to air, air humidity and oxygen actually leads to the gradual transformation of CuCl to Clinoatacamite. © 2023, The Authors. All rights reserved.

关键词： Copper compounds

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Magnetically tuned continuous transition from weak to strong coupling in terahertz magnon polaritons

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Physical Review Research 2023年第1期5卷 L012039-L012039页

作者： Andrey Baydin Kenji Hayashida Takuma Makihara Fuyang Tay Xiaoxuan Ma Wei Ren Guohong Ma G. Timothy Noe, II Ikufumi Katayama Jun Takeda Hiroyuki Nojiri Shixun Cao Motoaki Bamba Junichiro Kono Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Smalley-Curl Institute Rice University Houston Texas 77005 USA Division of Applied Physics Graduate School of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan Department of Physics and Astronomy Rice University Houston Texas 77005 USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas 77005 USA Department of Physics International Center of Quantum and Molecular Structures and Materials Genome Institute Shanghai University 200444 Shanghai China Department of Physics Graduate School of Engineering Science Yokohama National University Yokohama 240-8501 Japan Institute for Materials Research Tohoku University Sendai 980-8577 Japan The Hakubi Center for Advanced Research Kyoto University Kyoto 606-8502 Japan Department of Physics I Kyoto University Kyoto 606-8502 Japan PRESTO Japan Science and Technology Agency Kawaguchi 332-0012 Japan Department of Materials Science and NanoEngineering Rice University Houston Texas 77005 USA

Depending on the relative rates of coupling and dissipation, a light-matter coupled system is either in the weak- or strong-coupling regime. Here, we present a unique system where the coupling rate continuously increases with an externally applied magnetic field while the dissipation rate remains constant, allowing us to monitor a weak-to-strong coupling transition as a function of magnetic field. We observed a Rabi splitting of a terahertz magnon mode in yttrium orthoferrite above a threshold magnetic field of ∼14 T. Based on a microscopic theoretical model, we show that with increasing magnetic field the magnons transition into magnon polaritons through an exceptional point, which will open up new opportunities for in situ control of non-Hermitian systems.

关键词： Antiferromagnetism High magnetic fields Magneto-optics Magnons Polaritons Non-Hermitean systems Terahertz time-domain spectroscopy Transfer matrix method

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Effect of Surface Activation on the Corrosion Resistance of a MAO/Ni-P Composite Coating on LZ91 Magnesium Alloy

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Journal of the Taiwan Institute of Chemical Engineers 2023年第1期147卷

作者： Chen, Chi-An Lee, Jeou-Long Jian, Shun-Yi Lee, Chia-Yu Ger, Ming-Der Combination Medical Device Technology Division Medical Devices R&D Service Department Metal Industries Research & Development Centre Kaohsiung802 Taiwan Department of Chemical and Materials Engineering Lung Hwa University of Science and Technology Taoyuan330 Taiwan Department of Material Engineering Ming Chi University of Technology New Taipei City Taiwan Center for Plasma and Thin Film Technologies Ming Chi University of Technology New Taipei Taiwan Graduate School of Defense Science Chung Cheng Institute of Technology National Defense University Taoyuan Taiwan Department of Chemical & Materials Engineering Chung Cheng Institute of Technology National Defense University Taoyuan Taiwan System Engineering and Technology Program National Chiao Tung University Hsin-Chu Taiwan

Background: LZ91 Magnesium alloy with a dual-phase structure has improved mechanical properties and a low density of about 1.48 g/cm3 but their limited resistance to corrosion limits their application. Therefore, it is a great challenge to increase the stability of LZ91 alloys under corrosive factors and environments. Methods: This study uses micro-arc oxidation (MAO) and an electroless nickel-phosphorus (Ni-P) plated composite film to increase the corrosion resistance of LZ91 magnesium alloy. Before electroless Ni-P plating, the MAO layers are activated by palladium catalysts at different pH values to produce composite coatings. SEM, EDS and Image J are used to determine the surface properties and elemental composition of the samples. The corrosion resistance is measured using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. Findings: The results show that the MAO coating is activated by an acid catalyst and the surface is obviously corroded. The electroless Ni-P plating grows into the MAO coating and the substrate corrodes. Therefore, corrosive medium (chloride ion) easily enter to the substrate and pitting corrosion occurred. On the contrary, activation by a neutral catalyst (pH=7) maintains the original structure of the MAO coating and provides a good bonding interface for the Ni-P coating. Form the potentiodynamic analysis can be finds that the corrosion potential for the neutral catalyst treated sample is -0.35V and the corrosion current density value is 1.77×10−6 A/cm2, so the corrosion characteristic become better than the acid catalyst treated samples. In terms of the long-term resistance after 48 h, EIS analysis shows that the resistance value remains at about 7.6×104 Ω•cm2. A composite coating that is compact and with excellent resistance to corrosion resistance is produced, which provides better protection for LZ91 magnesium alloys. © 2023 Taiwan Institute of Chemical Engineers

关键词： Corrosion resistance

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Evidence for Two-Stage Hardening in an Al-Zn-Mg-Cu Alloy Processed by High-Pressure Torsion

SSRN

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SSRN 2022年

作者： dos Santos, Igor Cuzzuol Mazzer, Eric M. Figueiredo, Roberto B. Langdon, Terence G. Rodrigues Pereira, Pedro Henrique Graduate Program in Metallurgical Materials and Mining Engineering Universidade Federal de Minas Gerais MG Belo Horizonte31270-901 Brazil Department of Materials Science and Engineering Universidade Federal de São Carlos SP São Carlos13565-905 Brazil Department of Metallurgical and Materials Engineering Universidade Federal de Minas Gerais MG Belo Horizonte31270-901 Brazil Materials Research Group Department of Mechanical Engineering University of Southampton SouthamptonSO17 1BJ United Kingdom

Experiments were conducted to assess the effect of torsional straining on the microstructural evolution of an Al-5.7Zn-1.8Mg-2.1Cu alloy containing dispersed second phase particles prior to deformation. The results show that the material exhibits two distinct and consecutive hardening stages when processed through 1/8, 1, 5, 30, 50 and 100 turns in high-pressure torsion (HPT). There is an initial increase in the Vickers hardness from ~120 Hv in the unprocessed state to ~240 Hv after 1 turn. In this first stage, hardening occurs primarily through the accumulation and rearrangement of dislocations into fine cells/subgrains. A quasi-stationary condition is achieved with further straining where the microhardness remains nearly constant and the grain size is ~140 nm up to 30 revolutions. Thereafter, the microstructure consists of ultrafine and slightly elongated grains but the second phases are continuously fragmented. This fragmentation produces a new hardening stage and the development of a uniform array of highly elongated grains with an average size of ~93 nm after 100 HPT turns. It is shown that this two-stage hardening is consistent with conventional Hall-Petch strengthening and the development of the second stage is attributed to a reduction in grain boundary mobility due to the segregation of solutes. © 2022, The Authors. All rights reserved.

关键词： Aluminum alloys

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Anomalous properties of spark plasma sintered boron nitride solids

arXiv

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arXiv 2024年

作者： Biswas, Abhijit Serles, Peter Alvarez, Gustavo A. Schimpf, Jesse Hache, Michel Kong, Jonathan Demingos, Pedro Guerra Yuan, Bo Pieshkov, Tymofii S. Li, Chenxi Puthirath, Anand B. Gao, Bin Gray, Tia Zhang, Xiang Murukeshan, Jishnu Vajtai, Robert Dai, Pengcheng Singh, Chandra Veer Howe, Jane Zou, Yu Martin, Lane W. Clancy, James Patrick Tian, Zhiting Filleter, Tobin Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Department of Mechanical & Industrial Engineering University of Toronto 5 King’s College Road TorontoM5S 3G8 Canada Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Materials Science and Engineering University of California Berkeley United States Department of Materials Science and Engineering University of Toronto 184 College St TorontoM5S 3E4 Canada Department of Physics and Astronomy McMaster University HamiltonL8S 4M1 Canada Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Materials Sciences Division Lawrence Berkeley National Laboratory United States

Hexagonal boron nitride (h-BN) is brittle, however, its atomic-scale structural engineering can lead to unprecedented physical properties. Here we report the bulk synthesis of high-density crystalline h-BN solids by using high-temperature spark plasma sintering (SPS) of micron size h-BN powders. In addition to the high mechanical strength and ductile response of such materials, we have obtained anomalous values of dielectric constant beyond theoretical limits, high thermal conductivity, and exceptional neutron radiation shielding capability. Through exhaustive characterizations we reveal that SPS induces non-basal plane crystallinity, twisting of layers, and facilitates inter-grain fusion with a high degree of in-plane alignment across macroscale dimensions, resulting in near-theoretical density and anomalous properties. Our findings highlight the importance of material design, via new approaches such as twisting and interconnections between atomically thin layers, to create novel ceramics with properties that could go beyond their intrinsic theoretical predictions. © 2024, CC BY.

关键词： Spark plasma sintering

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Nonlocal phase-change metaoptics for reconfigurable nonvolatile image processing

arXiv

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arXiv 2024年

作者： Yang, Guoce Wang, Mengyun Lee, June Sang Farmakidis, Nikolaos Shields, Joe de Galarreta, Carlota Ruiz Kendall, Stuart Bertolotti, Jacopo Moskalenko, Andriy Huang, Kairan Alù, Andrea Wright, C. David Bhaskaran, Harish Department of Materials University of Oxford Parks Road OX1 3PH United Kingdom Department of Engineering University of Exeter ExeterEX4 QF United Kingdom Photonics Initiative Advanced Science Research Center City University of New York New York United States Physics Program Graduate Center City University of New York New York United States

The next generation of smart imaging and vision systems will require compact and tunable optical computing hardware to perform high-speed and low-power image processing. These requirements are driving the development of computing metasurfaces to realize efficient front-end analog optical pre-processors, especially for edge-detection capability. Yet, there is still a lack of reconfigurable or programmable schemes, which may drastically enhance the impact of these devices at the system level. Here, we propose and experimentally demonstrate a reconfigurable flat optical image processor using low-loss phase-change nonlocal metasurfaces. The metasurface is configured to realize different transfer functions in spatial frequency space, when transitioning the phase-change material between its amorphous and crystalline phases. This enables edge detection and bright-field imaging modes on the same device. The metasurface is compatible with a large numerical aperture of ~0.5, making it suitable for high resolution coherent optical imaging microscopy. The concept of phase-change reconfigurable nonlocal metasurfaces may enable emerging applications of artificial intelligence-assisted imaging and vision devices with switchable multitasking. © 2024, CC BY.

关键词： Image enhancement

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A Novel Method for the Fabrication of Antibacterial Stainless Steel with Uniform Silver Dispersions by Silver Nanoparticle/Polyethyleneimine Composites

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materials 2023年第10期16卷 3719-3719页

作者： Chih, Yu-Kun You, Jhu-Lin Lin, Wei-Hsuan Chang, Yen-Hao Tseng, Chun-Chieh Ger, Ming-Der Graduate School of Defense Science Chung Cheng Institute of Technology National Defense University Taoyuan335 Taiwan Department of Chemical and Materials Engineering Chung Cheng Institute of Technology National Defense University Taoyuan335 Taiwan System Engineering and Technology Program National Chiao Tung University Hsinchu300 Taiwan Combination Medical Device Technology Division Medical Devices and Opto-Electronics Equipment Department Metal Industries Research & Development Centre Kaohsiung821 Taiwan

Only a few studies have so far focused on the addition of silver to SS316L alloys by conventional sintering methods. Unfortunately, the metallurgical process of silver-containing antimicrobial SS is greatly limited due to the extremely low solubility of silver in iron and its tendency to precipitate at the grain boundaries, resulting in an inhomogeneous distribution of the antimicrobial phase and loss of antimicrobial properties. In this work, we present a novel approach to fabricate antibacterial stainless steel 316L by functional polyethyleneimine-glutaraldehyde copolymer (PEI-co-GA/Ag catalyst) composites. PEI is a highly branched cationic polymer, which makes it exhibit very good adhesion on the surface of the substrate. Unlike the effect of the conventional silver mirror reaction, the introduction of functional polymers can effectively improve the adhesion and distribution of Ag particles on the surface of 316LSS. It can be seen from the SEM images that a large number of silver particles are retained and well dispersed in 316LSS after sintering. PEI-co-GA/Ag 316LSS exhibits excellent antimicrobial properties and does not release free silver ions to affect the surrounding environment. Furthermore, the probable mechanism for the influence of the functional composites on the enhancement of adhesion is also proposed. The formation of a large number of hydrogen bonds and van der Waals forces, as well as the negative zeta potential of the 316LSS surface, can effectively enable the formation of a tight attraction between the Cu layer and the surface of 316LSS. These results meet our expectations of designing passive antimicrobial properties on the contact surface of medical devices. © 2023 by the authors.

关键词： Silver nanoparticles

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Unveiling the Bioactivities and Bioaccessibility of Phenolic Compounds from Organic Coffee Husks Using an in Vitro Digestion Model

SSRN

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SSRN 2023年

作者： Abreu, Thaianaly Leite Estévez, Mario de Carvalho, Leila Moreira de Medeiros, Lorena Lucena da Silva Pereira, Valquíria Cardoso Salu, Bruno Ramos Vilela Oliva, Maria Luiza Madruga, Marta Suely Alencar Bezerra, Taliana Kênia Post-Graduate Program in Food Science and Technology Department of Food Engineering Technology Centre Federal University of Paraiba PB João Pessoa58051-900 Brazil Research Institute of Meat and Meat Products IPROCAR TECAL Research Group Universidad de Extremadura Cáceres10003 Spain Department of Biochemistry Federal University of São Paulo SP São Paulo Brazil

The large amounts of by-products generated in the coffee industry are a problem for a sustainable agro-industry. The aim of this work was to investigate the occurrence of phenolic compounds in organic coffee husks and to evaluate their potential as a source of bioactive dietary components. To achieve this objective, three extracts were prepared, namely extractable polyphenols (EP), hydrolyzable non-extractable polyphenols (HNEP) and non-extractable polyphenols (NEP). These extracts were characterized and evaluated for their bioactive properties after simulated gastrointestinal digestion. The results show that the extraction process affects the occurrence of phenols from coffee peels, especially for caffeic acid, gallic acid, and chlorogenic acid. The condensed phenols and polyphenols found in the extracts and digests not only showed antioxidant properties against ABTS, FRAP and DPPH radicals, but also had remarkable bioavailability and anticoagulant potential. These results highlight the potential health benefits of phytochemicals from coffee husks and open new perspectives for the use of such compounds in dietary supplements. © 2023, The Authors. All rights reserved.

关键词： Antioxidants

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Structural, optical, and thermal properties of BN thin films grown on diamond via pulsed laser deposition

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Physical Review materials 2023年第9期7卷 094602-094602页

作者： Abhijit Biswas Gustavo A. Alvarez Tao Li Joyce Christiansen-Salameh Eugene Jeong Anand B. Puthirath Sathvik Ajay Iyengar Chenxi Li Tia Gray Xiang Zhang Tymofii S. Pieshkov Harikishan Kannan Jacob Elkins Robert Vajtai A. Glen Birdwell Mahesh R. Neupane Elias J. Garratt Bradford B. Pate Tony G. Ivanov Yuji Zhao Zhiting Tian Pulickel M. Ajayan Department of Materials Science and Nanoengineering Rice University Houston Texas 77005 USA Sibley School of Mechanical and Aerospace Engineering Cornell University Ithaca New York 14853 USA Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas 77005 USA DEVCOM Army Research Laboratory RF Devices and Circuits Adelphi Maryland 20783 USA Naval Research Laboratory Chemistry Division Washington District of Columbia 20375 USA

Heterostructures based on ultrawide-bandgap (UWBG) semiconductors (bandgap>4.0eV), such as BN and diamond, hold significant importance for the development of high-power electronics in the next generation. However, achieving in situ heteroepitaxy of BN/diamond or vice versa remains exceptionally challenging due to the complex growth kinetics involved. In this work, we grew BN thin film on (100) single-crystal diamonds using pulsed laser deposition and investigated its structural, magnetic, optical, and thermal properties. The structural analyses confirmed the growth of BN films, which exhibited diamagnetic behavior at room temperature. Notably, the film demonstrated anisotropic refractive index characteristics within the visible-to-near-infrared wavelength range. The room-temperature cross-plane thermal conductivity of BN is 1.53 ± 0.77 W/mK, while the thermal conductance of the BN/diamond interface is 20±2MW/m2K. These findings have significant implications for a range of device applications based on UWBG BN/diamond heterostructures.

关键词： Growth Thermal conductivity Boron nitride Thin films Wide band gap systems Film deposition Laser ablation Thermoreflectance

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Characterizing the mechanical response of metallic glasses to uniaxial tension using a spring network model

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Physical Review materials 2023年第7期7卷 073605-073605页

作者： Aya Nawano Weiwei Jin Jan Schroers Mark D. Shattuck Corey S. O'Hern 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

A coarse-grained spring network model is proposed for the prediction of the mechanical response of metallic glasses as a function of the microstructure prior to loading. This model describes the mechanical response of metallic glasses using a network of parallel springs that can break and reform, mimicking atomic rearrangements during deformation. We compare predictions of the spring network model for stress versus strain to results from numerical simulations of athermal quasistatic, uniaxial tensile deformation of Cu50Zr50 metallic glasses using Lennard-Jones (LJ) and embedded atom method (EAM) atomic interactions. We show that both the LJ and EAM models possess qualitatively similar stress σ versus strain γ curves. By specifying five parameters [ultimate strength, strain at ultimate strength, slopes of σ(γ) at γ=0 and at large strain, and strain at fracture where σ=0], we demonstrate that the spring network model can accurately describe the form of the stress-strain curves during uniaxial tension for the computational studies of Cu50Zr50, as well as recent experimental studies of several Zr-based metallic glasses.

关键词： Alloys Amorphous materials Glasses Packing & jamming problems Molecular dynamics

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