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arXiv 2021年

作者： Hu, Chongze Li, Yanwen Yu, Zhiyang Luo, Jian Department of Nanoengineering University of California La Jolla San DiegoCA92093 United States Program of Materials Science and Engineering University of California La Jolla San DiegoCA92093 United States State Key Laboratory of Photocatalysis on Energy and Environment College of Chemistry Fuzhou University Fujian Fuzhou350002 China Department of Physics Southern University of Science and Technology Guangdong Shenzhen518055 China

Computing the grain boundary (GB) counterparts to bulk phase diagrams represents an emerging research direction. Using a classical embrittlement model system Ga-doped Al alloy, this study demonstrates the feasibility of computing temperature- and composition-dependent GB diagrams to represent not only equilibrium thermodynamic and structural characters, but also mechanical properties. Specifically, hybrid Monte Carlo and molecular dynamics (MC/MD) simulations are used to obtain the equilibrium GB structure as a function of temperature and composition. Simulated GB structures are validated by aberration-corrected scanning transmission electron microscopy. Subsequently, MD tensile tests are performed on the simulated equilibrium GB structures. GB diagrams are computed for not only GB adsorption and structural disorder, but also interfacial structural and chemical widths, MD ultimate tensile strength, and MD tensile toughness. This study suggests a research direction to investigate GB composition–structure–property relationships via computing GB diagrams of thermodynamic, structural, and mechanical (or potentially other) properties. © 2021, CC BY.

关键词： Grain boundaries

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Additive manufacturing of fatigue resistant materials: Avoiding the early life crack initiation mechanisms during fabrication 30

Additive manufacturing of fatigue resistant materials: Avoid...

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30th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2019

作者： Pegues, Jonathan Roach, Michael Shamsaei, Nima Department of Mechanical Engineering Auburn University AuburnAL United States Auburn University AuburnAL United States Department of Biomedical Materials Science University of Mississippi Medical Center JacksonMS United States

The full potential of additive manufacturing (AM) has been limited by the process induced defects within the fabricated materials. Defects such as lack of fusions and gas entrapped pores act as stress concentrators and result in premature fatigue crack initiation, severely limiting the applicability of AM in fatigue-critical applications. However, by understanding the failure mechanisms associated with AM materials and leveraging the intimate localized thermal input (i.e. process conditions), the failure mechanisms for some materials may be avoided during the fabrication process. This study investigates the crack initiation behavior of an AM austenitic stainless steels subjected to fatigue testing. The microstructural features responsible for fatigue crack initiation are captured at the surface by ex-situ electron backscatter diffraction. Results show that the higher cooling rates during AM offer the opportunity to fabricate fatigue resistant austenitic stainless steel parts by avoiding the microstructural features that are most detrimental to fatigue performance. © Solid Freeform Fabrication 2019: Proceedings of the 30th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2019. All rights reserved.

关键词： Additives

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Dehydration Sensing of a Polyvinyl Alcohol Film via Plasmonic Nanoparticles

Dehydration Sensing of a Polyvinyl Alcohol Film via Plasmoni...

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MRS Advances

作者： Lisunova, Milana O. School of Materials Science and Engineering School of Chemistry and Biochemistry Georgia Institute of Technology AtlantaGA30332 United States MicroElectronics-Photonics Program Institute for Nanoscience and Engineering Ralph E. Martin Department of Chemical Engineering 3202 Bell Engineering Center University of Arkansas FayettevilleAR72701 United States

In situ, real-time monitoring of a dehydration of poly(vinyl alcohol) (PVA) film is researched. The technique based on the incorporation plasmonic nanocages (NCs) between the two identical layers of PVA, (PVA)/NCs/(PVA) film, and its sensitivity to the variation of the refractive index of the surrounding PVA film via desorption water. The dehydration time increases from 180 (s) to 1800 (s) as the content of the PVA in the films increases twice, from (PVA)/NCs/(PVA) to (PVA)2/NCs/(PVA)2. Such effect could be explained by different rate of the molecules desorption from the PVA based films. Specifically, the dehydration rate is of 0.22 (vol% per s) and 0.026 (vol% per s) for (PVA)/NCs/(PVA) and (PVA)2/NCs/(PVA)2 films, respectively. The dehydration rate constant reduces from -50×10-4 (s-1) to -4.3 ×10-4 (s-1) as the content of PVA increases from (PVA)/NCs/(PVA) to (PVA)2/NCs/(PVA)2 films, respectively. © materials Research Society 2019.

关键词： Plasmonics

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Phase transformation path in aluminum under ramp compression;simulation and experimental study

Research Square

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Research Square 2021年

作者： He, Lijie Polsin, Danae Zhang, Shuai Collins, Gilbert W. Abdolrahim, Niaz Materials Science Program University of Rochester RochesterNY14627 United States Departments of Mechanical Engineering University of Rochester RochesterNY14627 United States Laboratory for Laser Energetics University of Rochester RochesterNY14623 United States Department of Physics and Astronomy University of Rochester RochesterNY14627 United States

Identifying structure phase transformation path is essential but challenging in plastic deformation under high-pressure high-strain rate experiments. In this paper, we adopt a framework based on non-equilibrium molecular dynamics and virtual diffraction to reproduce the phase transformation event observed in laser-driven ramp compression. Our simulation results reveal the detailed phase transformation pathway with atomic-level deformation physics while the simulated stress-density response and virtual diffraction patterns match the experimental observation with great accuracy. © 2021, CC BY.

关键词： Plastic deformation

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Argonaute(AGO)proteins play an essential role in mediating BMP9-induced osteogenic signaling in mesenchymal stem cells(MSCs)

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Genes & Diseases 2021年第6期8卷 918-930页

作者： Yukun Mao Na Ni Linjuan Huang Jiaming Fan Hao Wang Fang He Qing Liu Deyao Shi Kai Fu Mikhail Pakvasa William Wagstaff Andrew Blake Tucker Connie Chen Russell R.Reid Rex C.Haydon Sherwin H.Ho Michael J.Lee Tong-Chuan He Jian Yang Le Shen Lin Cai Hue H.Luu Departments of Spine Surgery and Musculoskeletal Tumor and NeurosurgeryZhongnan Hospital of Wuhan UniversityWuhanHubei Province430072PR China Molecular Oncology Laboratory Department of Orthopaedic Surgery and Rehabilitation MedicineThe University of Chicago Medical CenterChicagoIL 60637USA Ministry of Education Key Laboratory of Diagnostic Medicine and the School of Laboratory MedicineChongqing Medical UniversityChongqing400016PR China Departments of Nephrology and Obstetrics and GynecologyThe First Affiliated Hospital of Chongqing Medical UniversityChongqing400016PR China Department of Spine Surgery Second Xiangya HospitalCentral South UniversityChangshaHunan Province410011PR China Department of Orthopaedic Surgery Union Hospital of Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei Province430022PR China Section of Plastic Surgery and Laboratory of Craniofacial Biology and Development and Section of Surgical ResearchDepartment of SurgeryThe University of Chicago Medical CenterChicagoIL 60637USA Department of Biomedical Engineering Materials Research InstituteThe Huck Institutes of the Life SciencesThe Pennsylvania State UniversityUniversity ParkPA 16802USA

As multipotent progenitor cells,mesenchymal stem cells(MSCs)can renew themselves and give rise to multiple lineages including osteoblastic,chondrogenic and adipogenic ***’s previously shown that BMP9 is the most potent BMP and induces osteogenic and adipogenic differentiation of ***,the molecular mechanism through which BMP9 regulates MSC differentiation remains poorly *** evidence indicates that noncoding RNAs,especially microRNAs,may play important roles in regulating MSC differentiation and bone *** highly conserved RNA binding proteins,Argonaute(AGO)proteins are essential components of the multi-protein RNA-induced silencing complexes(RISCs),which are critical for small RNA ***,we investigate possible roles of AGO proteins in BMP9-induced lineage-specific differentiation of *** first found that BMP9 upregulated the expression of Ago1,Ago2 and Ago3 in *** engineering multiplex siRNA vectors that express multiple siRNAs targeting individual Ago genes or all four Ago genes,we found that silencing individual Ago expression led to a decrease in BMP9-induced early osteogenic marker alkaline phosphatase(ALP)activity in ***,we demonstrated that simultaneously silencing all four Ago genes significantly diminished BMP9-induced osteogenic and adipogenic differentiation of MSCs and matrix mineralization,and ectopic bone ***,our findings strongly indicate that AGO proteins and associated small RNA biogenesis pathway play an essential role in mediating BMP9-induced osteogenic differentiation of MSCs.

关键词： Argonaute(AGO)proteins BMP9 Bone formation Lineage-specific differentiation Mesenchymal stem cells miRNA biogenesis Osteogenic signaling

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Alternation of Magnetic Anisotropy Accompanied by Metal-Insulator Transition in Strained Ultrathin Manganite Heterostructures

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Physical Review Applied 2021年第6期15卷 064019-064019页

作者： Masaki Kobayashi Le Duc Anh Masahiro Suzuki Shingo Kaneta-Takada Yukiharu Takeda Shin-ichi Fujimori Goro Shibata Arata Tanaka Masaaki Tanaka Shinobu Ohya Atsushi Fujimori Department of Electrical Engineering and Information Systems The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan Center for Spintronics Research Network The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan Institute of Engineering Innovation Graduate School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan PRESTO JST 4-1-8 Honcho Kawaguchi Saitama 332-0012 Japan Department of Physics The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-0033 Japan Materials Sciences Research Center Japan Atomic Energy Agency Sayo-gun Hyogo 679-5148 Japan Department of Applied Physics Tokyo University of Science Katsushika Tokyo 125-8585 Japan Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima 739-8530 Japan Department of Applied Physics Waseda University Okubo Shinjuku Tokyo 169-8555 Japan

A fundamental understanding of the interfacial magnetic properties in ferromagnetic heterostructures is essential for utilizing ferromagnetic materials for spintronic device applications. Here, we investigate the interfacial magnetic and electronic structures of epitaxial single-crystalline LaAlO3(LAO)/La0.6Sr0.4MnO3(LSMO)/Nb:SrTiO3(Nb:STO) heterostructures with varying LSMO layer thicknesses, in which the magnetic anisotropy strongly changes with the LSMO thickness due to the delicate balance between strains originating from both the Nb:STO and LAO layers, using x-ray magnetic circular dichroism and photoemission spectroscopy. We successfully detect the clear change of the magnetic behavior of the Mn ions concomitant with the thickness-dependent metal-insulator transition. Our results suggest that the double-exchange interaction induces ferromagnetism in the metallic LSMO film under tensile strain caused by the STO substrate, while the superexchange interaction determines the magnetic behavior in the insulating LSMO film under compressive strain originating from the top LAO layer. The change in strain, depending on LSMO layer thickness, is confirmed by scanning transmission electron microscopy. Based on those findings, the formation of a magnetic dead layer near the LAO/LSMO interface is attributed to competition between the superexchange interaction via Mn 3d3z2−r2 orbitals under compressive strain and the double-exchange interaction via the 3dx2−y2 orbitals. These findings provide key aspects of ferromagnetic oxide heterostructures for the development of spintronic device applications.

关键词： Electronic structure Ferromagnetism Magnetic anisotropy Metal-insulator transition Spintronics Transition metal oxides Photoemission spectroscopy X-ray magnetic circular dichroism

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Bridging the gap between simulated and experimental ionic conductivities in lithium superionic conductors

arXiv

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arXiv 2021年

作者： Qi, Ji Banerjee, Swastika Zuo, Yunxing Chen, Chi Zhu, Zhuoying Likhit, H.C. Manas Li, Xiangguo Ong, Shyue Ping Materials Science and Engineering Program University of California San Diego Mail Code 0448 9500 Gilman Dr San DiegoCA92093-0448 United States Department of NanoEngineering University of California San Diego Mail Code 0448 9500 Gilman Dr San DiegoCA92093-0448 United States

Lithium superionic conductors (LSCs) are of major importance as solid electrolytes for next-generation all-solid-state lithium-ion batteries. While ab initio molecular dynamics have been extensively applied to study these materials, there are often large discrepancies between predicted and experimentally measured ionic conductivities and activation energies due to the high temperatures and short time scales of such simulations. Here, we present a strategy to bridge this gap using moment tensor potentials (MTPs). We show that MTPs trained on energies and forces computed using the van der Waals optB88 functional yield much more accurate lattice parameters, which in turn leads to accurate prediction of ionic conductivities and activation energies for the Li0.33La0.56TiO3, Li3YCl6 and Li7P3S11 LSCs. NPT MD simulations using the optB88 MTPs also reveal that all three LSCs undergo a transition between two quasi-linear Arrhenius regimes at relatively low temperatures. This transition can be traced to an expansion in the number and diversity of diffusion pathways, in some cases with a change in the dimensionality of diffusion. This work presents not only an approach to develop high accuracy MTPs, but also outlines the diffusion characteristics for LSCs which is otherwise inaccessible through ab initio computation. © 2021, CC BY.

关键词： Solid electrolytes

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Structural modification of carbon black for improving the dielectric performance of epoxy based composites

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Advanced Industrial and engineering Polymer Research 2018年第1期1卷 111-117页

作者： Wang, Xin Li, Zewei Chen, Zhiwu Zeng, Lanying Sun, Luyi School of Materials Science and Engineering South China University of Technology Guangzhou China Polymer Program Institute of Materials Science and Department of Chemical & Biomolecular Engineering University of Connecticut Storrs CT United States

To explore a feasible strategy for improving the dielectric properties of carbon black (CB)/epoxy composites, CB@TiO2 core-shell particles and CB-SiO2 hybrid particles were prepared and incorporated into epoxy. The microstructures of CB, CB@TiO2, and CB-SiO2 particles, as well as the dielectric properties of their epoxy-based composites were investigated. The results showed that the composites containing CB-SiO2 hybrid particles possessed a higher dielectric constant than the ones containing pristine CB. The dielectric constant of the composite with 20.0 vol% CB-SiO2 reached 52.68 (1 kHz), which was ca. 4 times greater than that of the one containing 20.0 vol% pristine CB. Meanwhile, the composites containing CB@TiO2 core-shell particles exhibited suppressed values of dielectric loss. The permittivity of the composite with 20.0 vol% CB@TiO2 reached 19.52 (1 kHz), while its dielectric loss remained low (0.047 at 1 kHz). These results indicated that the dielectric properties of epoxy composites could be enhanced with the introduction of modified fillers. © 2018 Kingfa SCI. & TECH. CO., LTD.

关键词： Carbon black

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Curvy surface conformal ultra-thin transfer printed Sioptoelectronic penetrating microprobe arrays

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npj Flexible Electronics 2018年第1期2卷 8-13页

作者： Kyoseung Sim Zhoulyu Rao Yanbin Li Dong Yang Cunjiang Yu Materials Science and Engineering Program University of HoustonHoustonTX 77204USA Department of Mechanical Engineering University of HoustonHoustonTX 77204USA Department of Electrical and Computer Engineering University of HoustonHoustonTX 77204USA Department of Biomedical Engineering University of HoustonHoustonTX 77204USA

Penetrating neural probe arrays are powerful bio-integrated devices for studying basic neuroscience and applied neurophysiology,underlying neurological disorders,and understanding and regulating animal and human *** paper presents a penetrating microprobe array constructed in thin and flexible fashion,which can be seamlessly integrated with the soft curvy *** function of the microprobes is enabled by transfer printed ultra-thin Si *** a proof-of-concept device,microprobe array with Si photodetector arrays are demonstrated and their capability of mapping the photo intensity in space are *** design strategies of utilizing thin polyimide based microprobes and supporting substrate,and employing the heterogeneously integrated thin optoelectronics are keys to accomplish such a *** experimental and theoretical investigations illustrate the materials,manufacturing,mechanical and optoelectronic aspects of the *** this paper primarily focuses on the device platform development,the associated materials,manufacturing technologies,and device design strategy are applicable to more complex and multi-functionalities in penetrating probe array-based neural interfaces and can also find potential utilities in a wide range of bio-integrated systems.

关键词： optoelectronic arrays transfer

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Psychometric Evaluation of Multi-Point Bone-Conducted Tactile Stimulation on the Three Bony Landmarks of the Elbow

Psychometric Evaluation of Multi-Point Bone-Conducted Tactil...

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IEEE/RAS-EMBS International Conference on biomedical Robotics and Biomechatronics (BioRob)

作者： Raphael M. Mayer Alireza Mohammadi Ying Tan Gursel Alici Peter Choong Denny Oetomo Human Robotics Laboratory The University of Melbourne Australia School of Mechanical Materials Mechatronic and Biomedical Engineering University of Wollongong Australia ARC Centre of Excellence for Electromaterials Science Department of Surgery The University of Melbourne Australia

ISBN: (数字)9781728159072

ISBN: (纸本)9781728159089

Sensory feedback is highly desirable in upper limb prostheses as well as in human robot interaction and other human machine interfaces. Bone conduction as sensory feedback interface is a recently studied approach showing promising properties. A combination of different feedback information is often necessary for prosthetic grasping, thus multiple feedback channels are required for effective sensory feedback. The use of multiple bone conduction stimulation sites simultaneously has not yet been studied. In this paper, the psychometric evaluation of multiple stimulation sites on the physiologically given bony landmarks on the elbow is investigated. The proposed approach is evaluated on human-subject experiments with six able-bodied subjects and one subject with transradial amputation. Vibrotactile transducers are placed on the bony landmarks of the elbow to determine the identification rate of each stimulation point separately as well as the identification rate of the number of active stimulation points for different frequencies. The outcomes show high identification rates for a frequency range from 100 to 750 Hz whilst performance deteriorates to at chance level at higher frequencies. A decreasing performance in identifying the number of active stimulation sites for an increasing number of simultaneous active transducers was observed. The obtained good performance in location identification suggests that information can be encoded via the location of the stimulation.

关键词： Bones Transducers Robot sensing systems Elbow Prosthetics Skin Force

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