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A Variable Pitch Comb Fixture for Rayleigh Wave Generation and Reception

AIP Conference Proceedings 2007年第1期894卷 1684-1690页

作者： Daniel J. Barnard Materials and Engineering Physics Program Ames Laboratory USDOE Ames IA 50011

Several methods are available for the generation and reception of Rayleigh waves on a part surface. The use of the so‐called “comb” is one method, where the comb elements or “fingers” contact the surface with a spacing between adjacent fingers equal to the Rayleigh wavelength of the substrate for a given frequency. Although efficient and simple, a fixed pitch comb is typically useful only at one frequency for a particular substrate. A simple “parallel link” fixture has been developed where the pitch of the fingers can be varied over a range of spacings, allowing the operator to set the comb pitch for a particular material/frequency at will. The comb elements may be glued to the wear plate of a longitudinal transducer or simply fluid coupled. Elements of the fixture and tests results of the fixtures used for generating Rayleigh waves on aluminum and steel substrates are shown.

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Extreme Damping in Composite materials with a Negative Stiffness Phase

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Physical Review Letters 2001年第13期86卷 2897-2897页

作者： R. S. Lakes Department of Engineering Physics Engineering Mechanics Program Materials Science Program University of Wisconsin 147 ERB 1500 Engineering Drive Madison Wisconsin 53705

Composites with negative stiffness inclusions in a viscoelastic matrix are shown to have higher stiffness and mechanical damping tanδ than that of either constituent and exceeding conventional bounds. The causal mechanism is a greater deformation in and near the inclusions than the composite as a whole. Though a block of negative stiffness is unstable, negative stiffness inclusions in a composite can be stabilized by the surrounding matrix. Such inclusions may be made from single domains of ferroelastic material below its phase transition temperature or from prebuckled lumped elements.

关键词： .Bulk Formulas inclusions Unstable shear modulus volume fraction composite materials ferroelastic HASHIN-SHTRIKMAN Negative Stiffness transition temperature positive stiffness mechanical damping tand single domains

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Tribological characteristics of AIMgB14 and nanocomposite AIMgB14-TiB2 superhard coatings

Tribological characteristics of AIMgB14 and nanocomposite AI...

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2008 STLE/ASME International Joint Tribology Conference, IJTC 2008

作者： Qu, Jun Blau, Peter J. Zhu, Dong Cook, Bruce A. Elmoursi, Alaa A. Materials Science and Technology Division Oak Ridge National Laboratory United States Innovation Center Eaton Corporation United States Materials and Engineering Physics Program Ames Laboratory United States

ISBN: (纸本)9780791843369

This study investigated the friction and wear characteristics of two super-hard coatings on M2 steel. One was A1MgB14, produced by pulsed laser deposition (PLD), and the other was a nanocomposite of A1MgB 14-TiB2 produced by physical vapor deposition (PVD). Tests were conducted under unidirectional and reciprocating sliding against AISI 52100 bearing steel in both dry and oil-lubricated conditions. The A1MgB 14, coating exhibited an encouraging but short-lived low friction stage (μ = 02) in dry sliding. The A1MgB14-TiB2 coating reduced the wear rates by one order of magnitude relative to the M2 steel and three orders of magnitude for the counterface in dry sliding. This nanocomposite coating also demonstrated significant extension (>***) of the low friction (non-scuffing) stage when sliding under starved lubrication. Copyright © 2008 by ASME.

关键词： Tribology

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Application of numerical method and statistical analysis in the integrated intensity calculation of the peaks from the X-ray diffraction (XRD) pattern of α-iron 8th

Application of numerical method and statistical analysis in ...

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8th International Conference on materials Science and Technology, MSAT 2014

作者： Chakartnarodom, Parinya Kongkajun, Nuntaporn Senthongkaew, Payoon Department of Materials Engineering Faculty of Engineering Kasetsart University Chatuchak Bangkok10900 Thailand Materials Science Program Department of Physics Faculty of Science and Technology Thammasat University KlongLuang Prathumthani12121 Thailand Materials Innovation Center Faculty of Engineering Kasetsart University Chatuchak Bangkok10900 Thailand

ISBN: (纸本)9783038355526

The aim of this work is to analyze the error of the calculated integrated intensity of the xray peaks of a-iron (BCC-Fe) powder from x-ray diffraction (XRD) pattern by using the numerical method and the statistical analysis. The a-Fe powder was characterized by the x-ray diffractometer using step scan mode, step sizes 0.03° 2θ and 0.05° 2θ, and preset times from 0.1 to 3.5 s. The integrated intensity (Iint) of an x-ray peak and its error (ΔIint) were calculated using numerical method. The correlation between the relative error ((ΔIint/Iint) × 100) and the preset time or step size were analyzed by the statistical analysis methods which are linear regression and statistical hypothesis testing. The results from the statistical analysis at significance level of 0.05 show that the relative error (y = (ΔIint/Iint) × 100) correlate with x = preset time or integrated intensity by y = a1/xa2 when a1 and a2 are the positive constants. From the mathematical model, for this work, the step size does not affect the relative error. However, the increasing of preset time reduces relative error on integrated intensity calculation. To minimize the error on XRD analysis, the preset time should be greater than one second. Moreover, on a XRD pattern, the lower integrated intensity peak has the higher relative error. © (2015).

关键词： X ray diffraction

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Study of the bio-interaction of nitrogen-doped graphene quantum dots with human serum albumin aiming a quantification method

Nano Trends

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Nano Trends 2025年 9卷

作者： Soto-Chochocca, Rocio de Farias, Renan Lira Gutierrez-Beleño, Luis Miguel Letichevsky, Sonia Freire-Jr, Fernando Lázaro Serge-Correales, York E. Gonçalves, Rogéria R. Pedrozo-Peñafiel, Marlin Aucelio, Ricardo Q. Postgraduate Program in Metrology (PósMQI) Pontifical Catholic University of Rio de Janeiro (PUC-Rio) RJ Brazil Department of Chemistry Pontifical Catholic University of Rio de Janeiro (PUC- Rio) RJ Rio de Janeiro Brazil Department of Chemical and Materials Engineering Pontifical Catholic University of Rio de Janeiro (PUC- Rio) RJ Rio de Janeiro Brazil Department of Physics Pontifical Catholic University of Rio de Janeiro (PUC- Rio) RJ Rio de Janeiro Brazil Department of Chemistry University of São Paulo (USP) SP São Paulo Brazil

In recent years, carbon-based nanomaterials, such as graphene quantum dots (GQDs), have garnered significant attention due to their remarkable physicochemical and biological properties. This work presents a study evaluating the interaction between N-doped GQDs, produced from a mixture of citric acid and urea (referred here as GQDs-U), with human serum albumin (HSA). The GQDs-U were characterized using spectroscopic techniques, and their concentration was expressed in terms of total carbon content in aqueous dispersion. They present average diameter of about 8 nm, with average hydrodynamic diameter of around 12 nm, and a surface charge of -7 mV at pH 7.4. Assays revealed that a progressive increase in GQDs-U concentration led to the quenching of HSA fluorescence with quenching directly correlated with temperature, also indicating a mixed quenching mechanism with a predominance of the dynamic type, suggesting mutual conformational rearrangements of HSA/GQDs-U before reaching thermodynamic equilibrium. Additionally, it was shown that GQDs-U could be used as a probe to quantify HAS with the increase in photoluminescence of GQDs-U upon the addition of HSA demonstrating effective energy transfer, as GQDs-U were found to promote quenching in HSA photoluminescence. This study indicated sound evidence of stability of the nanomaterial, in aqueous dispersions, in terms of optical and morphological properties. The stability over time suggests the viability of GQDs-U as analytical probes for HSA even after a long period (30 days) of GQDs-U aging. The work also enhanced the understanding of the complex time-structure-activity relationship in this biomolecule/nanomaterial system. © 2025 The Authors

关键词： Graphene quantum dots HSA quantification Human serum albumin Photoluminescence Stability study

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Migration and proliferation drive the emergence of patterns in co-cultures of differentiating vascular progenitor cells

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Mathematical Biosciences and engineering 2024年第8期21卷 6731-6757页

作者： Zamora Alvarado, Jose E. McCloskey, Kara E. Gopinathan, Ajay School of Engineering University of California Merced MercedCA95343 United States Graduate Program in Materials and Biomaterials Science and Engineering University of California Merced MercedCA95343 United States Department of Physics University of California Merced MercedCA95343 United States

Vascular cells self-organize into unique structures guided by cell proliferation, migration, and/or differentiation from neighboring cells, mechanical factors, and/or soluble signals. However, the relative contribution of each of these factors remains unclear. Our objective was to develop a computational model to explore the different factors affecting the emerging micropatterns in 2D. This was accomplished by developing a stochastic on-lattice population-based model starting with vascular progenitor cells with the potential to proliferate, migrate, and/or differentiate into either endothelial cells or smooth muscle cells. The simulation results yielded patterns that were qualitatively and quantitatively consistent with experimental observations. Our results suggested that post-differentiation cell migration and proliferation when balanced could generate between 30–70% of each cell type enabling the formation of vascular patterns. Moreover, the cell-to-cell sensing could enhance the robustness of this patterning. These findings computationally supported that 2D patterning is mechanistically similar to current microfluidic platforms that take advantage of the migration-directed self-assembly of mature endothelial and mural cells to generate perfusable 3D vasculature in permissible hydrogel environments and suggest that stem or progenitor cells may not be fully necessary components in many tissue formations like those formed by vasculogenesis. ©2024 the Author(s)

关键词： Endothelial cells

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Enhanced terahertz emission from SI-GaAs with a sub-wavelength 1D metal array 11

Enhanced terahertz emission from SI-GaAs with a sub-waveleng...

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11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015

作者： Faustino, Maria Angela B. Lopez, Lorenzo P. Afalla, Jessica Muldera, Joselito Felix, Mark Jayson Salvador, Arnel A. Somintac, Armando S. Estacio, Elmer S. Materials Science and Engineering Program University of the Philippines Diliman Quezon City Philippines National Institute of Physics University of the Philippines Diliman Quezon City Philippines

Terahertz emission enhancement in SI-GaAs, having a deposited periodic 1D metal array, is reported. The one order enhancement is currently attributed to the localization of the terahertz electromagnetic field at the G... 详细信息

ISBN: (纸本)9781467371094

关键词： Gallium arsenide

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Chiral phonon-induced magnetization in cerium fluorides

Chiral phonon-induced magnetization in cerium fluorides

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

作者： Luo, Jiaming Lin, Tong Zhang, Junjie Chen, Xiaotong Blackert, Elizabeth R. Xu, Rui Yakobson, Boris I. Zhu, Hanyu Department of Materials Science and Nano Engineering Rice University Houston United States Applied Physics Graduate Program Rice University Houston United States

We report that circularly polarized terahertz light pulses can drive chiral phonons, which then induce an effective quasi-static magnetic field on the order of 1 tesla to polarize the paramagnetic cerium fluoride. ... 详细信息

ISBN: (纸本)9781957171395

关键词： Phonons

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Increased terahertz emission from SI-GaAs deposited with sub-wavelength spacing metal line array 40

Increased terahertz emission from SI-GaAs deposited with sub...

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40th International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2015

作者： Faustino, Maria Angela B. Lopez, Lorenzo P. Afalla, Jessica Pauline Muldera, Joselito Felix, Mark Jayson Salvador, Arnel A. Somintac, Armando S. Estacio, Elmer S. Materials Science and Engineering Program University of the Philippines Quezon City1101 Philippines National Institute of Physics University of the Philippines Quezon City1101 Philippines

ISBN: (纸本)9781479982721

Increased terahertz (THz) emission of surface modified semi-insulating gallium arsenide (SI-GaAs) is reported. A metal line array with sub-wavelength spacing was fabricated via e-beam deposition and THz measurements were done in the transmission excitation geometry. Results show an order of magnitude THz broadband emission enhancement. Pump-power dependent measurements were also utilized which shows a nonlinear dependence with the THz integrated intensity. This broadband enhancement is currently attributed to super transmission owing to a non-linear optical effect that may be related to surface plasmon resonance. © 2015 IEEE.

关键词： Surface plasmon resonance

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Coupling of mechanical deformation and electromagnetic fields in biological cells

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Reviews of Modern physics 2022年第2期94卷 025003-025003页

作者： Mehdi Torbati Kosar Mozaffari Liping Liu Pradeep Sharma Departments of Mechanical Engineering Physics and the Materials Science and Engineering Program University of Houston Houston Texas 77204 USA

The cell, as the most fundamental unit of life, is a microcosm of biology in which the confluence of nearly all aspects of classical physics (mechanics, statistical physics, condensed matter, and electromagnetism) plays out. This leads to a rich and complex emergent behavior that determines the entire gamut of biological functions. Specifically, at the cellular scale, mechanical forces and deformations are inextricably linked to electrical fields (and, to a lesser degree, magnetic fields). This in turn is responsible for phenomenology such as cell-cell communication, morphological evolution, cell fusion, self-assembly, cell fission, magnetoreception, endocytosis, and adhesion, among others. From the viewpoint of biomedicine, cellular response to the combined influence of electrical, magnetic, and mechanical fields has applications in cancer treatment, targeted transfer of medicine, gene therapy, and wound amelioration. As an example of the profound influence of the combined electrical-mechanical coupling, one needs to take cognizance only of the operation of ion channels that form the basis for our sensing system (such as hearing, sight, and tactile sense). The coupled mechanical and electromagnetic behavior of a cell is a highly interdisciplinary endeavor and this review provides a distillation of both the theoretical underpinnings of the subject and the pertinent biological interpretation. The key developments pertaining to this topic are reviewed, a unified mathematical framework that couples nonlinear deformation and electromagnetic behavior as germane for soft biological entities is summarized, gaps in current knowledge are pointed out, and the central issues that are pertinent to future research are commented upon.

关键词： Electromagnetism Mechanical deformation

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