检索结果-内蒙古大学图书馆

SSRN 2023年

作者： Santos, Ian Daniell Hofmann, Mario Tjarks, Patrick Muthu, Jeyavelan Lin, You-Chen Yen, Zhi-Long Chand, Pradyumna Kumar Raman, Radha Rouhani, Mehdi Jeng, Yeau-Ren Nguyen, Dinh-Tuan Hsieh, Ya-Ping Department of Physics National Taiwan University Taipei106 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica National Taiwan University Taiwan Institute of Physics Academia Sinica Taipei106 Taiwan Institute for Atomic and Molecular Sciences Academia Sinica Taipei106 Taiwan Department of Chemistry National Taiwan University Taipei106 Taiwan Department of Physics National Central University Taoyuan320 Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica National Central University Taiwan Department of Materials Science and Engineering National Cheng Kung University Tainan70101 Taiwan

We here demonstrate the strengthening of graphene, an atomically thin carbon allotrope, by out-of-plane folding. Through lateral confinement of graphene at the water-air interface, buckling was induced in suspended flakes leading to an unexpected folding transition beyond a critical surface pressure. The emergence of folding was confirmed by in-situ reflectivity and ex-situ microscopy and imparts graphene assemblies with a unique "z-laminated" morphology. Molecular dynamics simulations indicate an enhanced adhesion between neighboring flakes compared to lateral sliding which was confirmed by a surface pressure hysteresis during the folding process. Mechanical testing reveals superior Young’s modulus and Yield strength when compared to conventional graphene assemblies and even compared to composites. We demonstrate the potential of folding for graphene-based structural materials, tribological layers, and functional electrochemical coatings. Finally, the complete recyclability of z-laminated graphene opens up new routes towards sustainable nanostructured materials. © 2023, The Authors. All rights reserved.

关键词： Graphene

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The Influence of Nbb Inoculation on Dendritic Spacing and Grain Size of an Aluminum 2017 Alloy at Different Cooling Rates

SSRN

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SSRN 2022年

作者： Silva, Argos Soares de Albuquerque Sousa, Sarah Maria de Gouveia, Guilherme Lisboa Garcia, Amauri Spinelli, José Eduardo Department of Materials Engineering Federal University of São Carlos UFSCar SP São Carlos13565-905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil Department of Manufacturing and Materials Engineering University of Campinas SP Campinas13083-860 Brazil

The Al-4Cu-Mg 2017 alloy is a significant Al extrusion alloy. As a result, knowing its behavior in terms of grain refining during casting stages becomes critical for the next processing steps. In the face of the shortcomings exhibited by TiB inoculants, the addition of NbB could be tested for this alloy as an alternative. The present article investigates the effects of NbB addition on grain size (GS), on secondary dendrite arm spacing (λ2) and on hardness of centrifugally cast (CC) and directionally solidified (DS) 2017 alloy samples, encompassing a broad range of cooling rates and solidification conditions. The λ2 did not change much as a result of the NbB inoculation, either for DS or CC samples, decreasing from 7.2 μm to 7.0 μm in the case of the 4 mm-thick CC samples and increasing from 17.0 μm to 22.5 μm in the case of the DS samples. The average GS, on the other hand, reduced from 293 μm to 136 μm for the NbB-containing CC samples and from 756 μm to 313 μm for the DS samples associated with cooling rates of 10 K/s. Both processes can achieve nearly the same GS reduction ratio, namely 2.2 for the CC and 2.5 for the DS. This implies that GS reduction ratio was barely affected if similar cooling rates were compared while taking the experimental range for both processes into account. Moreover, Vickers hardness results revealed that GS had little influence on this property for both alloys studied. The experimentally obtained data translated a variety of solidification condition outlines for the 2017 alloy. Through this data, understanding of an alternative inoculant in a significant Al alloy series advanced significantly. © 2022, The Authors. All rights reserved.

关键词： Solidification

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Influence of the Cooling Rate on the Solidification Path and Microstructure of a Alcocrfeni2.1

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SSRN 2023年

作者： Oliveira, Pedro Henrique Fernandes Mancilha, Pedro Henrique Siqueira Reyes, Rodrigo André Valenzuela de Gouveia, Guilherme Lisboa Bolfarini, Claudemiro Spinelli, José Eduardo Coury, Francisco Gil Department of Materials Engineering Federal University of São Carlos Rod. Washington Luís Km 235 SP São CarlosCEP 13565-905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luís Km 235 SP São CarlosCEP 13565-905 Brazil

The AlCoCrFeNi2.1 alloy is a promising eutectic high entropy alloy which may act as an in-situ composite, showing a trade-off between mechanical properties and ductility. Controlling the microstructure formation is crucial for achieving the best balance since it is closely related to the cooling rates during solidification. Hence, the present study determined the relationship between different cooling rates and the formed microstructures. As such, the AlCoCrFeNi2.1 alloy was subjected to a directional solidification process so that samples solidified at different cooling rates could be generated. The examined samples corresponded to a range from 1 to 6 °C/s, which resulted in microstructures composed of primary dendrites and uncoupled eutectic, with varying secondary dendritic spacings from 18 to 54 mm and eutectic spacings from 4.5 to 10 mm. . The use of CALPHAD, XRD, SEM-EDS, and EBSD phase mapping enabled to determine that the primary FCC dendrites formed in all samples enveloped by the FCC+B2 eutectic. Moreover, the solidification cooling rate affected both dendritic (primary phase) and eutectic length-scales. Finally, the solidification sequence path was able to be changed, and the primary FCC dendrites were also able to form, due to the non-equilibrium nature of the solidification process, which imposed particular segregation and growth conditions. © 2023, The Authors. All rights reserved.

关键词： Solidification

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Spectroscopic and Interferometric Sum-Frequency Imaging of Strongly Coupled Phonon Polaritons in SiC Metasurfaces

arXiv

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arXiv 2023年

作者： Niemann, Richarda Mueller, Niclas S. Wasserroth, Sören Lu, Guanyu Wolf, Martin Caldwell, Joshua D. Paarmann, Alexander Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6 Berlin14195 Germany Department of Mechanical Engineering Vanderbilt University NashvilleTN37235 United States Interdisciplinary Materials Science Graduate Program Vanderbilt University NashvilleTN37235 United States

Phonon polaritons enable waveguiding and localization of infrared light with extreme confinement and low losses. The spatial propagation and spectral resonances of such polaritons are usually probed with complementary techniques such as near-field optical microscopy and far-field reflection spectroscopy. Here, we introduce infrared-visible sum-frequency spectro-microscopy as a tool for spectroscopic imaging of phonon polaritons. The technique simultaneously provides sub-wavelength spatial resolution and highly-resolved spectral resonance information. This is implemented by resonantly exciting polaritons using a tunable infrared laser and wide-field microscopic detection of the upconverted light. We employ this technique to image hybridization and strong coupling of localized and propagating surface phonon polaritons in metasurfaces of SiC micropillars. Spectro-microscopy allows us to measure the polariton dispersion simultaneously in momentum space by angle-dependent resonance imaging, and in real space by polariton interferometry. Notably, we directly visualize how strong coupling affects the spatial localization of polaritons, inaccessible with conventional spectroscopic techniques. We further observe the formation of edge states at excitation frequencies where strong coupling prevents polariton propagation into the metasurface. Our approach is applicable to the wide range of polaritonic materials with broken inversion symmetry and can be used as a fast and non-perturbative tool to image polariton hybridization and propagation. © 2023, CC BY.

关键词： Polariton

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Zwitterionic modified and freeze-thaw reinforced foldable hydrogel as intraocular lens for posterior capsule opacification prevention

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Biomaterials 2024年 309卷 122593-122593页

作者： Yang, Cheng-Jui Huang, Wei-Lun Yang, Yu Kuan, Chen-Hsiang Tseng, Ching-Li Wang, Tzu-Wei Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan Department of Ophthalmology National Taiwan University Hospital Hsin-Cchu Branch Hsinchu Taiwan Interdisciplinary Program of Life Science and Medicine National Tsing Hua University Hsinchu Taiwan Division of Plastic Surgery Department of Surgery National Taiwan University Hospital Taipei Taiwan Graduate Institute of Clinical Medicine College of Medicine National Taiwan University Taipei Taiwan Research Center for Developmental Biology and Regenerative Medicine National Taiwan University Taipei Taiwan Graduate Institute of Biomedical Materials and Tissue Engineering Taipei Medical University Taipei Taiwan

Posterior capsule opacification (PCO) is a predominant postoperative complication, often leading to visual impairment due to the aberrant proliferation and adhesion of lens epithelial cells (LECs) and protein precipitates subsequent to intraocular lens (IOL) implantation. To address this clinical issue, a foldable and antifouling sharp-edged IOL implant based on naturally-derived cellulose hydrogel is synthesized. The mechanical strength and transparency of the hydrogel is enhanced via repeated freeze-thaw (FT) cycles. The incorporated zwitterionic modifications can remarkably prevent the incidence of PCO by exhibiting proteins repulsion and cell anti-adhesion properties. The graft of dopamine onto both the haptic and the periphery of the posterior surface ensures the adhesion of the hydrogel to the posterior capsule and impedes the migration of LECs without compromising transparency. In in vivo study, the zwitterionic modified foldable hydrogel exhibits uveal and capsular biocompatibility synchronously with no signs of inflammatory response and prevent PCO formation, better than that of commercialized and PEG-modified IOL. With foldability, endurability, antifouling effect, and adhesive to posterior capsule, the reported hydrogel featuring heterogeneous surface design displays great potential to eradicate PCO and attain post-operative efficacy after cataract surgery. © 2024 Elsevier Ltd

关键词： Hydrogels

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Picosecond optical-to-x-ray (Cd,Mg)Te radiation detectors

Picosecond optical-to-x-ray (Cd,Mg)Te radiation detectors

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Conference on Lasers and Electro-Optics (CLEO)

作者： J. Cheng I. Komissarov G. Chen D. Chakraborty S. Kutcher H. Chen S. Trivedi Roman Sobolewski Materials Science Graduate Program University of Rochester Rochester New York USA Laboratory for Laser Energetics University of Rochester Rochester New York USA Department of Electrical and Computer Engineering University of Rochester Rochester New York USA Brimrose Technology Corp Sparks Maryland USA

We developed a dual optical/x-ray ultrafast photodetector based on in-house grown Cd 0.97 Mg 0.03 Te single crystals. The detector is characterized by ~200 ps full-width-at-half-maximum, readout-electronics limited p... 详细信息

ISBN: (纸本)9781957171258

关键词： Femtosecond lasers Photodetectors Photon counting Pump probe spectroscopy Radiation detectors Ti:sapphire lasers

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Microwave Synthesis of Nanostructured High Entropy Spinel

SSRN

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SSRN 2022年

作者： Gunnewiek, Rodolfo Foster Klein Cardoso, André L.F. Perdomo, Claudia P.F. Foschiani, Beatriz G. Xaraba, Julia A. Zabotto, Fabio L. Federal University of Sao Carlos Graduate Program in Materials Science and Engineering SP Sao Carlos Brazil Federal University of Sao Carlos Department of Materials Engineering SP São Carlos Brazil Federal University of Sao Carlos Department of Physics SP São Carlos Brazil

A single-phase cubic high entropy spinel (HES) (CoCrFeMnNi)3O4 was microwave synthesized by a polymer-based method. The complete microwave-synthesis took no longer than 2 hours. The HEŚs were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS). After calcination of 800 and 900 °C, the powders showed nanostructured cubic single-phases. The band gap energy (Eg) of the microwave irradiated HES was 2.2 eV compared to the 2.45 eV of the conventionally calcined. These Eg values indicate application possibilities in the field of catalytic reforming of carbon dioxide as a promising catalyst with tunable properties. © 2022, The Authors. All rights reserved.

关键词： Entropy

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Coherent Acoustic Phonons in Bi2Se3 Ultrathin Films Probed by Femtosecond, Optical Pump-Probe Spectroscopy

Coherent Acoustic Phonons in Bi2Se3 Ultrathin Films Probed b...

引用

CLEO: Fundamental science, CLEO:FS 2024 - Part of Conference on Lasers and Electro-Optics, CLEO 2024

作者： Cheng, Jing Niherysh, Kiryl A. Francis, Peter Chakraborty, Debamitra Lombardi, Floriana Erts, Donats Prischepa, Serghej L. Laszcz, Adam Komissarov, Ivan V. Sobolewski, Roman Materials Science Graduate Program University of Rochester RochesterNY14627 United States Laboratory for Laser Energetics University of Rochester RochesterNY14623-1299 United States Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden Institute of Chemical Physics University of Latvia Riga Latvia Department of Electrical and Computer Engineering University of Rochester RochesterNY14627 United States Dipartimento di Fisica "E.R. Caianiello" Università degli Studi di Salerno Sa FiscianoI-84084 Italy Lukasiewicz Research Network Institute of Microelectronics and Photonics WarszawaPL-02668 Poland

ISBN: (纸本)9781957171395

The dynamics of coherent acoustic phonons in the Bi2Se3 layered crystal system are investigated. The findings reveal that the frequency evolution of breathing modes with the number of the material quintuple layers and the dispersion relation both can be explained by a modified chain model with a nonuniform coupling force. © Optica Publishing Group 2024, © 2024 The Author(s)

关键词： Ultrathin films

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Machine-learned molecular surface and its application to implicit solvent simulations

arXiv

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arXiv 2021年

作者： Wei, Haixin Zhao, Zekai Luo, Ray Departments of Materials Science and Engineering Molecular Biology and Biochemistry Chemical and Biomolecular Engineering and Biomedical Engineering Graduate Program in Chemical and Materials Physics University of California IrvineCA92697 United States

Implicit solvent models, such as Poisson-Boltzmann models, play important roles in computational studies of biomolecules. A vital step in almost all implicit solvent models is to determine the solvent-solute interface, and the solvent excluded surface (SES) is the most widely used interface definition in these models. However, classical algorithms used for computing SES are geometry-based, thus neither suitable for parallel implementations nor convenient for obtaining surface derivatives. To address the limitations, we explored a machine learning strategy to obtain a level-set formulation for the SES. The training process was conducted in three steps, eventually leading to a model with over 95% agreement with the classical SES. Visualization of tested molecular surfaces shows that the machine-learned SES overlaps with the classical SES on almost all situations. We also implemented the machine-learned SES into the Amber/PBSA program to study its performance on reaction field energy calculation. The analysis shows that the two sets of reaction field energies are highly consistent with 1% deviation on average. Given its level-set formulation, we expect the machine-learned SES to be applied in molecular simulations that require either surface derivatives or high efficiency on parallel computing platforms. © 2021, CC BY.

关键词： Solvents

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Identifying the minimal sets of distance restraints for FRET-assisted protein structural modeling

arXiv

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arXiv 2024年

作者： Liu, Zhuoyi Grigas, Alex T. Sumner, Jacob Knab, Edward Davis, Caitlin M. O’Hern, Corey S. Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Department of Chemistry Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

Proteins naturally occur in crowded cellular environments and interact with other proteins, nucleic acids, and organelles. Since most previous experimental protein structure determination techniques require that proteins occur in idealized, non-physiological environments, the effects of realistic cellular environments on protein structure are largely unexplored. Recently, Förster resonance energy transfer (FRET) has been shown to be an effective experimental method for investigating protein structure in vivo. Inter-residue distances measured in vivo can be incorporated as restraints in molecular dynamics (MD) simulations to model protein structural dynamics in vivo. Since most FRET studies only obtain inter-residue separations for a small number of amino acid pairs, it is important to determine the minimum number of restraints in the MD simulations that are required to achieve a given root-mean-square deviation (RMSD) from the experimental structural ensemble. Further, what is the optimal method for selecting these inter-residue restraints? Here, we implement several methods for selecting the most important FRET pairs and determine the number of pairs Nr that are needed to induce conformational changes in proteins between two experimentally determined structures. We find that enforcing only a small fraction of restraints, Nr/N 0.08, where N is the number of amino acids, can induce the conformational changes. These results establish the efficacy of FRET-assisted MD simulations for atomic scale structural modeling of proteins in vivo. © 2024, CC BY.

关键词： Conformations

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