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arXiv 2022年

作者： Qin, Mingde Shivakumar, Sashank Luo, Jian Department of NanoEngineering Program of Materials Science and Engineering University of California San Diego La Jolla CA92093 United States

Nanocrystalline alloys (nanoalloys) are prone to grain growth. It is known that grain boundary segregation and precipitation can stabilize nanoalloys, but the stabilization becomes less effective at high temperatures and adding grain growth inhibitors often reduces sinterability. Herein, we have simultaneously achieved improved sinterability and exceptional high-temperature stability for a class of MoNbTaTiW-based refractory high-entropy nanoalloys (RHENs). Bulk pellets of RHENs were fabricated through planetary ball milling and spark plasma sintering, achieving 93-96% relative densities with 50-100 nm grain sizes for three compositions. For example, Mo17.8Nb17.8Ta17.8Ti17.8W17.8Ni6Zr5 sintered at 1300 °C attained ~96% relative density with ~55 nm mean grain size. Moreover, these RHENs exhibited exceptional stability at 1300 °C. Both Ti17.8Nb17.8Mo17.8Ta17.8W17.8Ni6Zr5 and Mo18.8Nb18.8Ta18.8Ti18.8W18.8Ni6 retained 96% of the theoretical densities after five hours annealing at 1300 °C. Notably, the addition of Ni, a well-known sintering aid for activated sintering of refractory metals such as W and Mo, in high-entropy MoNbTaTiW can promote sintering while maintaining high-temperature stability against rapid grain growth, which can be explained by hypothesized effects of high-entropy grain boundaries. These RHENs possess some of the highest temperature stability achieved for nanoalloys and ultrafine-grained metals. © 2022, CC BY.

关键词： Grain boundaries

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!D-architected gratings for polarization-sensitive, nature-inspired structural color

arXiv

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arXiv 2024年

作者： Ibarra Miranda, Moisés H. Osterberg, Lars W. Shah, Dev H. Regulagadda, Kartik Poulikakos, Lisa V. Department of Mechanical and Aerospace Engineering Program of Materials Science and Engineering University of California San Diego La Jolla CA United States Program of Materials Science and Engineering University of California San Diego La Jolla CA United States Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla CA United States Laboratory for Multiphase Thermofluidics and Surface Nanoengineering Department of Mechanical Engineering University of California BerkeleyCA United States

Structural coloration, a color-generation mechanism often found in nature, arises from light-matter interactions such as diffraction, interference and scattering, with micro- and nanostructured elements. Herein, we systematically study anisotropic,:D-architected grating structures with polarization-tunable optical properties, inspired by the vivid blue of Morpho butterfly wings. Using two-photon lithography, we fabricate multilayered gratings, varying parameters such as height (through scanning speed and laser power), periodicity, and number of layers. In transmission, significant color transitions from blue to brown were identified when varying structural parameters and incident light polarization conditions (azimuthal angle and ellipticity). Based on thin film diffraction efficiency theory in the Raman-Nath regime, optical characterization results are analytically explained, evaluating the impact of each parameter variation. Overall, these findings contribute to technological implementations of polarization-sensitive,:D-architected gratings for structural color applications. Copyright © 2024, The Authors. All rights reserved.

关键词： Color

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Plasticity Encoding and Mapping during Elementary Loading for Accelerated Mechanical Properties Prediction

arXiv

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arXiv 2025年

作者： Calvat, Mathieu Bean, Chris Anjaria, Dhruv Wang, Haoren Vecchio, Kenneth Stinville, J.C. Materials Science and Engineering Department University of Illinois Urbana-Champaign UrbanaIL United States Department of NanoEngineering University of California La Jolla San DiegoCA United States

Encoding metal plasticity captured from high-resolution digital image correlation (DIC) can be leveraged to predict a wide range of monotonic and cyclic macroscopic properties of metallic materials. To capture the spatial heterogeneity of plasticity that develops in metals, latent space features describing plasticity of a small region are spatially mapped across a large field of view while maintaining the same spatial relationships as the experimental measurements. Latent space feature maps capture the complexity and heterogeneity of metal plasticity as a low-dimensional representation. These feature maps are then used to train a convolutional neural network-based model to predict monotonic and cyclic macroscopic properties. The approach is demonstrated on a large set of face-centered cubic metals, enabling rapid and accurate property prediction. The effects of hyperparameters and training strategies are analyzed, and the extension of the proposed approach to a broader range of metallic materials and loading conditions is discussed. © 2025, CC BY-NC-SA.

关键词： Plasticity

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An expandable chamber for safe brain retraction: new technologies in the field of transcranial endoscopic surgery

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Journal of Zhejiang University-science B(Biomedicine & Biotechnology) 2023年第4期24卷 326-335页

作者： Elena ROCA Anna GOBETTI Giovanna CORNACCHIA Oscar VIVALDI Barbara BUFFOLI Giorgio RAMORINO Head and Neck Department NeurosurgeryIstituto Ospedaliero Fondazione Poliambulanza25124 BresciaItaly Technology for Health PhD Program University of Brescia25124 BresciaItaly Materials Science and Technology at Department of Mechanical and Industrial Engineering University of Brescia25123 BresciaItaly Metallurgy at Department of Mechanical and Industrial Engineering University of Brescia25123 BresciaItaly Anatomy and Physiopathology Division Department of Clinical and Experimental SciencesUniversity of Brescia25123 BresciaItaly

Neurosurgery is a highly specialized field:it often involves surgical manipulation of noble structures and cerebral retraction is frequently necessary to reach deep-seated brain *** are still no reliable methods preventing possible retraction *** objective of this study was to design work chambers well suited for transcranial endoscopic surgery while providing safe retraction of the surrounding brain *** chamber is designed to be inserted close to the intracranial point of interest;once it is best placed it can be *** should guarantee an appreciable workspace similar to that of current neurosurgical *** experimental aspect of this study involved the use of a force sensor to evaluate the pressures exerted on the brain tissue during the retraction *** pterional craniotomy,pressure measurements were made during retraction with the use of a conventional metal spatula with different *** that,although the force values necessary for retraction and exerted on the spatula by the neurosurgeon are the same,the local pressure exerted on the parenchyma at the edge of the spatula at different inclinations varied greatly.A new method of cerebral retraction using a chamber retractor(CR)has been designed to avoid any type of complication due to spatula edge overpressures and to maintain acceptable pressure values exerted on the parenchyma.

关键词： Brain retraction Spatula Brain retractor design Brain retraction injury Retraction complication Transcranial endoscopic surgery

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Phase Prediction, Microstructure and Mechanical Property of Spark Plasma Sintered Titanium Aluminide-Based High-Entropy Alloys

SSRN

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SSRN 2024年

作者： Anamu, Ufoma Silas Ayodele, O.O. Olorundaisi, Emmanuel Odetola, P.I. Jen, T.-C. Olubambi, Peter Apata Centre for Nanoengineering and Advanced Materials School of Mining Metallurgy and Chemical Engineering University of Johannesburg Johannesburg2092 South Africa Department of Mechanical Engineering Science University of Johannesburg South Africa

Four novel septenary high-entropy alloys (HEAs) were developed as follows: an equiatomic Ti14.286Al14.286Cr14.286Nb14.286Ni14.286Cu14.286Co14.286 (A), Ti20Al20Cr5Nb5Ni19Cu12Co19 (B), Ti20Al20Cr5Nb5Ni18Cu14Co18 (C) and Ti20Al20Cr5Nb5Ni17Cu16Co17 (D) alloys. The HEAs were designed theoretically by thermo-physical calculations and CALPHAD-based tool (Thermo-Calc) to predict the thermodynamic properties and the phases’ stability in the alloys prior to the experimentation process. After high-energy ball-milling of the elemental powders at 10 hrs milling time, spark plasma sintering (SPS) technique was employed for the fabrication of the HEAs at a sintering temperature of 900 oC, heating rate of 100 oC/min, pressure of 50 MPa, and a dwelling time of 5 min. X-ray diffractometer, scanning electron microscope, and Vickers micro-hardness tester were used to investigate the distinct phase constituents, microstructures and hardness property of the fabricated HEAs. The ThermoCalc simulation reveals the presence of primarily five stable phases, namely- BCC(B2), FCC(L12), Sigma, Heusler and C15(Laves). High consolidation and appropriate inter-particle bonding of the admixed powder aggregate, and equiaxed crystal structure was observed in the SPSed HEAs depicted in the micrographs. Alloy B exhibits an optimum micro-hardness of 859 HV/0.3, with a nano crystallite size of 10.3764 µm and, a micro-strain value of 0.3045. An increase in the composition of the Cu at the expense of Ni and Co stabilizes the FCC structure, and this translates to a subsequent decrease in the hardness value from alloy B to D. A comparison of the phases and micro-hardness results from the experimental procedure follows a similar trend with that obtained from the Thermo-Calc simulation. © 2024, The Authors. All rights reserved.

关键词： Spark plasma sintering

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Na-22 for Safeguarding and Mass Accounting of Molten Salt Systems

Na-22 for Safeguarding and Mass Accounting of Molten Salt Sy...

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2023 Transactions of the American Nuclear Society Winter Conference and Expo, ANS 2023

作者： Zile, Matthew Van Kauffman, Andrew Herminghuysen, Kevin Li, Shelly Simpson, Michael Kandlakunta, Praneeth Cao, Guoping Cao, Lei R. Nuclear Engineering Program Department of Mechanical and Aerospace Engineering Ohio State University United States Nuclear Reactor Laboratory College of Engineering Ohio State University United States Department of Materials Science and Engineering University of Utah.Idaho National Laboratory United States

The Na-22based radioactive tracer dilution (RTD) technique has been previously demonstrated for mass accounting in small quantities of clean molten salt for bench top testing. While the concept of RTD has proven to be a promising method, it has lacked further validation in large-scale quantities and in fuel-bearing salt. Towards that end, two research initiatives are on-going at The Ohio State University (OSU) and Idaho National Laboratory (INL) to address these challenges. Current work at OSU is focused on evaluating the RTD using the full gamma-ray spectrum of fission products produced by irradiating fuel bearing salt, i.e., UCl3-MgCl2-KCl in a 500-kW research reactor. The INL team has successfully demonstrated the RTD for mass determination using an 8-kg LiCl-KCl-UCl3salt for uranium electrorefining and is currentlyseeking to validate the tracer method with large(about 60 kg)molten salt system(bearing fission products) in an oxide reduction (OR) facility for spent nuclear fuel (SNF) reprocessing. © 2023 American Nuclear Society. All rights reserved.

关键词： Fission products

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Design of the Continuous Gravity-Driven Multiple-Effect Thermal System (G-METS) for Efficient Low-Cost Magnesium Recycling

Design of the Continuous Gravity-Driven Multiple-Effect Ther...

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Magnesium Technology Symposium held during the 152nd TMS Annual Meeting and Exhibition, TMS 2023

作者： Sehar, Daniel Mcarthur Espinosa, Gabriel Telgerafchi, Armaghan Ehsani Chinwego, Chinenye Lynch, Keira Perrin, Benjamin Powell, Adam Materials Science and Engineering Program Department of Mechanical Engineering Worcester Polytechnic Institute WorcesterMA United States Department of Mechanical Engineering Worcester Polytechnic Institute WorcesterMA United States 100 Institute Rd WorcesterMA01609 United States

ISBN: (纸本)9783031226458

Recent global supply shortages, combined with need for light-weight structural components for efficient transportation, have led to very high prices for magnesium due to its low density and high part stiffness/weight. This study continues prior work on magnesium recycling using multiple-effect distillation with gravity as the parameter to create the pressure difference between effects, called G-METS. The long-term vision is for continuous distillation, but experiments to date have only used batch distillers with maximum rate of 1 kg/h. and minimum energy consumption of 2 kWh/kg. This study presents the design of laboratory-scale continuous distiller including a custom-made furnace to sustain a high-power density and temperature gradient for rapid boiling and efficient recovery of magnesium. © The Minerals, Metals & materials Society 2023.

关键词： Distillation

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A physics-constrained deep learning surrogate model of the runaway electron avalanche growth rate

arXiv

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arXiv 2024年

作者： Arnaud, Jonathan Mark, Tyler McDevitt, Christopher J. Nuclear Engineering Program Department of Materials Science and Engineering University of Florida GainesvilleFL32611 United States

A surrogate model of the runaway electron avalanche growth rate in a magnetic fusion plasma is developed. This is accomplished by employing a physics-informed neural network (PINN) to learn the parametric solution of the adjoint to the relativistic Fokker-Planck equation. The resulting PINN is able to evaluate the runaway probability function across a broad range of parameters in the absence of any synthetic or experimental data. This surrogate of the adjoint relativistic Fokker-Planck equation is then used to infer the avalanche growth rate as a function of the electric field, synchrotron radiation and effective charge. Predictions of the avalanche PINN are compared against first principle calculations of the avalanche growth rate with excellent agreement observed across a broad range of parameters. © 2024, CC BY.

关键词： Fokker Planck equation

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Self-Attenuating Graphene-Based Antennas Utilizing Polyvinylidene Fluoride (PVDF) Substrates

Self-Attenuating Graphene-Based Antennas Utilizing Polyvinyl...

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Microwave and Antenna Symposium (IMAS), International

作者： Josef Frankhouse Evans Addo-Mensah Uche Wejinya Department of Mechanical Engineering University of Arkansas - Fayetteville Materials Science and Engineering Graduate Program University of Arkansas - Fayetteville

ISBN: (数字)9798350356359

ISBN: (纸本)9798350356366

In this study, a Terahertz (THz) band antenna which can regulate its own resonant frequency without the requirement of manual adjustment is simulated. A polyvinylidene fluoride (PVDF) substrate is applied onto a rectangular graphene patch antenna. With a voltage potential applied onto the PVDF, the patch antenna can attenuate its frequency by physically changing the shape of the antenna, and in turn its resonant frequency. These antennas are within a 0.1 THz band between 1.32 THz to 1.22 THz measured from a radial bend of a flat surface to r = 75 μm, fitting into a return loss (S11) above -30 dB. Although the return loss did not show consistency, the resonating frequency shifted at a linear rate relative to the cylindrical bending.

关键词： Microwave antennas Patch antennas Graphene Resonant frequency Prototypes Bandwidth Bending Loss measurement Substrates Terahertz communications

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Superhydrophobic fluoride conversion coating on bioresorbable magnesium alloy——fabrication,characterization,degradation and cytocompatibility with BMSCs

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Journal of Magnesium and Alloys 2021年第4期9卷 1252-1266页

作者： Chunyan Zhanga Shiyu Zhang Dongwei Sun Jiajia Lin Fancheng Meng Huinan Liu School of Materials Science&Engineering Chongqing University of TechnologyNo.69 Hongguang AvenueChongqing 400054China Department of Bioengineering and the Materials Science and Engineering ProgramUniversity of CaliforniaRiverside900 University AvenueMSE 205RiversideCA 92521USA

A micro-nano structure CaF_(2)chemical conversion layer was prepared on fluoride-treated AZ31 alloy,then the composite fluoride conversion film(CaF_(2)/MgF_(2))was modified by stearic acid(SA)and fabricated a superhydrophobic *** fluoride-treated magnesium,fluoride conversion film and superhydrophobic coating were characterized by SEM,EDS,XRD and *** properties of coatings1 adhesion and corrosion resistance were evaluated via tape test and electrochemical *** cytocompatibility of the MgF_(2),CaF_(2)and superhydrophobic CaF_(2)/SA surface was investigated with bone marrow-derived mesenchymal stem cells(BMSCs)by direct culture for 24 *** results showed that the superhydrophobic fluoride conversion coating composed of inner MgF_(2)layer and the outer CaF_(2)/SA composite layer had an average water contact angle of 152°.SA infiltrated into the micro-nano structure CaF_(2)layer and formed a strong adhesion with CaF_(2)***,the super-hydrophobic coating showed higher barrier properties and corrosion resistance compared with the fluoride conversion film and fluoride-treated AZ31 *** BMSC adhesion test results demonstrated MgF_(2)CaF_(2)and CaF_(2)/SA coatings were all nontoxic to *** the condition of in direct contact with cells,MgF_(2)showed higher cell density and enhanced the BMSCs proliferation,while CaF_(2)and CaF_(2)/SA coating showed no statistically difference in cell density compared with glass reference but the CaF_(2)and CaF_(2)/SA coating were not conducive to BMSCs adhesion.

关键词： Biodegradable Magnesium alloy Superhydrophobic Fluoride conversion film Cytocompatibility

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