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M. Roy, Arunabha. "Evolution of Martensitic Nanostructure in NiAl Alloys: Tip Splitting and Bending". Material Science Research India 17, SpecialIssue1 (1.08.2020): 03–06. http://dx.doi.org/10.13005/msri.17.special-issue1.02.
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A phase-field (PF) model for the phase transformation (PT) between austenite and martensite and twinning between two martensite is presented where PT is described by a single order parameter. Such a description helps us to obtain the analytical solution of interface energetics and kinetics. PF-elasticity problems are solved for cubic-to-tetragonal PT in NiAl. The stress and temperature-induced PT and corresponding twinning and growth of the martensitic phase inside a nanocrystal are simulated. It reproduces nontrivial experimentally observed nanostructure such as splitting and bending of martensitic nanostructure as well as twins crossing. The evolution and morphology of such interesting nanostructures are discussed.
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Chowdhury, R., S. Adhikari i F. Scarpa. "Elasticity and piezoelectricity of zinc oxide nanostructure". Physica E: Low-dimensional Systems and Nanostructures 42, nr 8 (czerwiec 2010): 2036–40. http://dx.doi.org/10.1016/j.physe.2010.03.018.
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ISLAM, Z. M., P. JIA i C. W. LIM. "TORSIONAL WAVE PROPAGATION AND VIBRATION OF CIRCULAR NANOSTRUCTURES BASED ON NONLOCAL ELASTICITY THEORY". International Journal of Applied Mechanics 06, nr 02 (17.03.2014): 1450011. http://dx.doi.org/10.1142/s1758825114500112.
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The presence of size effects represented by a small nanoscale on torsional wave propagation properties of circular nanostructure, such as nanoshafts, nanorods and nanotubes, is investigated. Based on the nonlocal elasticity theory, the dynamic equation of motion for the structure is formulated. By using the derived equation, simple analytical solutions for the relation between wavenumber and frequency via the differential nonlocal constitutive relation and the numerical solutions for a discrete nonlocal model via the integral nonlocal constitutive relation have been obtained. This results not only show that the dispersion characteristics of circular nanostructures are greatly affected by the small nanoscale and the classical theory overestimates the stiffness of nanostructures, but also highlights the significance of the integral nonlocal model which is able to capture some boundary characteristics that do not appear in the differential nonlocal model.
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Dindarloo, Mohammad Hassan, Li Li, Rossana Dimitri i Francesco Tornabene. "Nonlocal Elasticity Response of Doubly-Curved Nanoshells". Symmetry 12, nr 3 (16.03.2020): 466. http://dx.doi.org/10.3390/sym12030466.
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In this paper, we focus on the bending behavior of isotropic doubly-curved nanoshells based on a high-order shear deformation theory, whose shape functions are selected as an accurate combination of exponential and trigonometric functions instead of the classical polynomial functions. The small-scale effect of the nanostructure is modeled according to the differential law consequent, but is not equivalent to the strain-driven nonlocal integral theory of elasticity equipped with Helmholtz’s averaging kernel. The governing equations of the problem are obtained from the Hamilton’s principle, whereas the Navier’s series are proposed for a closed form solution of the structural problem involving simply-supported nanostructures. The work provides a unified framework for the bending study of both thin and thick symmetric doubly-curved shallow and deep nanoshells, while investigating spherical and cylindrical panels subjected to a point or a sinusoidal loading condition. The effect of several parameters, such as the nonlocal parameter, as well as the mechanical and geometrical properties, is investigated on the bending deflection of isotropic doubly-curved shallow and deep nanoshells. The numerical results from our investigation could be considered as valid benchmarks in the literature for possible further analyses of doubly-curved applications in nanotechnology.
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Zhang, Y., L. J. Zhuo i H. S. Zhao. "Determining the effects of surface elasticity and surface stress by measuring the shifts of resonant frequencies". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 469, nr 2159 (8.11.2013): 20130449. http://dx.doi.org/10.1098/rspa.2013.0449.
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Both surface elasticity and surface stress can result in changes of resonant frequencies of a micro/nanostructure. There are infinite combinations of surface elasticity and surface stress that can cause the same variation for one resonant frequency. However, as shown in this study, there is only one combination resulting in the same variations for two resonant frequencies, which thus provides an efficient and practical method of determining the effects of both surface elasticity and surface stress other than an atomistic simulation. The errors caused by the different models of surface stress and mode shape change due to axial loading are also discussed.
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Elbourne, Aaron, James Chapman, Amy Gelmi, Daniel Cozzolino, Russell J. Crawford i Vi Khanh Truong. "Bacterial-nanostructure interactions: The role of cell elasticity and adhesion forces". Journal of Colloid and Interface Science 546 (czerwiec 2019): 192–210. http://dx.doi.org/10.1016/j.jcis.2019.03.050.
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Tamm, Aile, Tauno Kahro, Helle-Mai Piirsoo i Taivo Jõgiaas. "Atomic-Layer-Deposition-Made Very Thin Layer of Al2O3, Improves the Young’s Modulus of Graphene". Applied Sciences 12, nr 5 (27.02.2022): 2491. http://dx.doi.org/10.3390/app12052491.
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Nanostructures with graphene make them highly promising for nanoelectronics, memristor devices, nanosensors and electrodes for energy storage. In some devices the mechanical properties of graphene are important. Therefore, nanoindentation has been used to measure the mechanical properties of polycrystalline graphene in a nanostructure containing metal oxide and graphene. In this study the graphene was transferred, prior to the deposition of the metal oxide overlayers, to the Si/SiO2 substrate were SiO2 thickness was 300 nm. The atomic layer deposition (ALD) process for making a very thin film of Al2O3 (thickness comparable with graphene) was applied to improve the elasticity of graphene. For the alumina film the Al(CH3)3 and H2O were used as the precursors. According to the micro-Raman analysis, after the Al2O3 deposition process, the G-and 2D-bands of graphene slightly broadened but the overall quality did not change (D-band was mostly absent). The chosen process did not decrease the graphene quality and the improvement in elastic modulus is significant. In case the load was 10 mN, the Young’s modulus of Si/SiO2/Graphene nanostructure was 96 GPa and after 5 ALD cycles of Al2O3 on graphene (Si/SiO2/Graphene/Al2O3) it increased up to 125 GPa. Our work highlights the correlation between nanoindentation and defects appearance in graphene.
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Ivanova, Elena P., Denver P. Linklater, Marco Werner, Vladimir A. Baulin, XiuMei Xu, Nandi Vrancken, Sergey Rubanov i in. "The multi-faceted mechano-bactericidal mechanism of nanostructured surfaces". Proceedings of the National Academy of Sciences 117, nr 23 (26.05.2020): 12598–605. http://dx.doi.org/10.1073/pnas.1916680117.
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The mechano-bactericidal activity of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, particularly in the current era of emerging antibiotic resistance. This work demonstrates the effects of an incremental increase of nanopillar height on nanostructure-induced bacterial cell death. We propose that the mechanical lysis of bacterial cells can be influenced by the degree of elasticity and clustering of highly ordered silicon nanopillar arrays. Herein, silicon nanopillar arrays with diameter 35 nm, periodicity 90 nm and increasing heights of 220, 360, and 420 nm were fabricated using deep UV immersion lithography. Nanoarrays of 360-nm-height pillars exhibited the highest degree of bactericidal activity toward both Gram stain-negativePseudomonas aeruginosaand Gram stain-positiveStaphylococcus aureusbacteria, inducing 95 ± 5% and 83 ± 12% cell death, respectively. At heights of 360 nm, increased nanopillar elasticity contributes to the onset of pillar deformation in response to bacterial adhesion to the surface. Theoretical analyses of pillar elasticity confirm that deflection, deformation force, and mechanical energies are more significant for the substrata possessing more flexible pillars. Increased storage and release of mechanical energy may explain the enhanced bactericidal action of these nanopillar arrays toward bacterial cells contacting the surface; however, with further increase of nanopillar height (420 nm), the forces (and tensions) can be partially compensated by irreversible interpillar adhesion that reduces their bactericidal effect. These findings can be used to inform the design of next-generation mechano-responsive surfaces with tuneable bactericidal characteristics for antimicrobial surface technologies.
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Taghvaei, Mohammad Mahdi, Hossein Mostaan, Mahdi Rafiei, Hamid Reza Bakhsheshi-Rad i Filippo Berto. "Nanoscale Tribological Properties of Nanostructure Fe3Al and (Fe,Ti)3Al Compounds Fabricated by Spark Plasma Sintering Method". Metals 12, nr 7 (23.06.2022): 1077. http://dx.doi.org/10.3390/met12071077.
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Nanostructured powder particles of Fe3Al and (Fe,Ti)3Al phases were produced using mechanical alloying. These intermetallic phases with a nearly complete density were consolidated by spark plasma sintering. The mechanical properties of the bulk samples, i.e., elasticity modulus, hardness, and plasticity index, and also their tribological behavior were investigated using nanoindentation and nano-scratch tests. It was found that both Fe3Al and (Fe,Ti)3Al phases can be synthesized after 30 h of high-energy ball milling. In addition, no phase evolution was observed after spark plasma sintering. An analysis of the atomic force microscope images obtained from the nanoindentation tests showed a higher elasticity modulus, higher hardness, and lower plasticity index due to the addition of Ti to the Fe3Al system. (Fe,Ti)3Al displayed better tribological properties as compared with Fe3Al. A smaller volume of the scratched line was clearly seen in the atomic force microscope images of the nanostructured (Fe,Ti)3Al compound.
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Hashemzadeh, Allahverdi, Ghorbani, Soleymani, Kocsis, Fischer, Ertl i Naderi-Manesh. "Gold Nanowires/Fibrin Nanostructure as Microfluidics Platforms for Enhancing Stem Cell Differentiation: Bio-AFM Study". Micromachines 11, nr 1 (30.12.2019): 50. http://dx.doi.org/10.3390/mi11010050.
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Organ-on-a-chip technology has gained great interest in recent years given its ability to control the spatio-temporal microenvironments of cells and tissues precisely. While physical parameters of the respective niche such as microchannel network sizes, geometric features, flow rates, and shear forces, as well as oxygen tension and concentration gradients, have been optimized for stem cell cultures, little has been done to improve cell-matrix interactions in microphysiological systems. Specifically, detailed research on the effect of matrix elasticity and extracellular matrix (ECM) nanotopography on stem cell differentiation are still in its infancy, an aspect that is known to alter a stem cell’s fate. Although a wide range of hydrogels such as gelatin, collagen, fibrin, and others are available for stem cell chip cultivations, only a limited number of elasticities are generally employed. Matrix elasticity and the corresponding nanotopography are key factors that guide stem cell differentiation. Given this, we investigated the addition of gold nanowires into hydrogels to create a tunable biointerface that could be readily integrated into any organ-on-a-chip and cell chip system. In the presented work, we investigated the matrix elasticity (Young’s modulus, stiffness, adhesive force, and roughness) and nanotopography of gold nanowire loaded onto fibrin hydrogels using the bio-AFM (atomic force microscopy) method. Additionally, we investigated the capacity of human amniotic mesenchymal stem cells (hAMSCs) to differentiate into osteo- and chondrogenic lineages. Our results demonstrated that nanogold structured-hydrogels promoted differentiation of hAMSCs as shown by a significant increase in Collagen I and II production. Additionally, there was enhanced calcium mineralization activity and proteoglycans formation after a cultivation period of two weeks within microfluidic devices.
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Brusnitsina, Evgenia, Razilia Muftakhetdinova, Grigoriy Yakovlev i Victor Grokhovsky. "Nanoindentation of Phase and Structural Components of Pallasite Seymchan (PMG)". KnE Engineering 1, nr 1 (15.04.2019): 34. http://dx.doi.org/10.18502/keg.v1i1.4388.
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Determination of mechanical properties in multiphase bodies of extraterrestrial originis a fundamental task. In this work the hardness and Young’s modulus in the Seymchanpallasite were determined in kamacite α-Fe (Ni, Co), taenite γ-Fe (Ni, Co), plessite (α+γ),tetrataenite FeNi using nanoindentation technique. For the first time, the hardness andmodulus of elasticity of a two-phase nanostructure of cloudy zone FeNi+α-Fe(Ni,Co),formed as a result of very slow cooling (about 1 K/Myr), was determined.
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Florini, Nikoletta, George P. Dimitrakopulos, Joseph Kioseoglou, Nikos T. Pelekanos i Thomas Kehagias. "Strain field determination in III–V heteroepitaxy coupling finite elements with experimental and theoretical techniques at the nanoscale". Journal of the Mechanical Behavior of Materials 26, nr 1-2 (25.04.2017): 1–8. http://dx.doi.org/10.1515/jmbm-2017-0009.
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AbstractWe are briefly reviewing the current status of elastic strain field determination in III–V heteroepitaxial nanostructures, linking finite elements (FE) calculations with quantitative nanoscale imaging and atomistic calculation techniques. III–V semiconductor nanostructure systems of various dimensions are evaluated in terms of their importance in photonic and microelectronic devices. As elastic strain distribution inside nano-heterostructures has a significant impact on the alloy composition, and thus their electronic properties, it is important to accurately map its components both at the interface plane and along the growth direction. Therefore, we focus on the determination of the stress-strain fields in III–V heteroepitaxial nanostructures by experimental and theoretical methods with emphasis on the numerical FE method by means of anisotropic continuum elasticity (CE) approximation. Subsequently, we present our contribution to the field by coupling FE simulations on InAs quantum dots (QDs) grown on (211)B GaAs substrate, either uncapped or buried, and GaAs/AlGaAs core-shell nanowires (NWs) grown on (111) Si, with quantitative high-resolution transmission electron microscopy (HRTEM) methods and atomistic molecular dynamics (MD) calculations. Full determination of the elastic strain distribution can be exploited for band gap tailoring of the heterostructures by controlling the content of the active elements, and thus influence the emitted radiation.
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Fatahian, E., Ebrahim Hosseini i H. Fatahian. "A review on recent research studies on vibration analysis of fluid-conveying nanotubes". International Journal of Engineering Technology and Sciences 7, nr 2 (23.09.2020): 42–54. http://dx.doi.org/10.15282/ijets.7.2.2020.1004.
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Nanotube (such as carbon and boron nitride nanotubes) is a key component of modern technology applications of nanostructures due to their unique mechanical, electrical, and physical characteristics such as high elasticity modulus, suitable heat transfer, and electrical conductivity. Carbon and boron nitride nanotubes are among the promising choices in nano-fluidic, gas storage, and drug delivery systems due to their hollow cylindrical shape and appropriate chemical, mechanical, and physical properties. Thermal vibration assessment should be conducted on fluid-conveying carbon nanotubes since the effect of thermal fluctuations on the mechanical characteristics of nanostructure are significant. Previous studies have revealed that when thermal vibration is taken into account, quantum effects can become extremely important in nanoscale electronics and structures. Hence, the present review focuses mostly on previous work on fluid-conveying nanotubes and the dynamical characteristics of size-dependent vibration and non-local strain gradient theory of fluid-conveying nanotubes. Furthermore, a special effort is made to address recent and rare investigations on the vibration of fluid-conveying nanotubes in thermal environment, as well as thermal vibration concerns of carbon nanotubes.
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Zhang, Lele, Jing Zhao i Guoquan Nie. "Shear Horizontal Surface Waves in a Layered Piezoelectric Nanostructure with Surface Effects". Micromachines 13, nr 10 (11.10.2022): 1711. http://dx.doi.org/10.3390/mi13101711.
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This work aims to provide a fundamental understanding on the dispersive behaviors of shear horizontal (SH) surface waves propagating in a layered piezoelectric nanostructure consisting of an elastic substrate and a piezoelectric nanofilm by considering the surface effects. Theoretical derivation based on the surface piezoelectricity model was conducted for this purpose, and analytic expressions of the dispersion equation under the nonclassical mechanical and electrical boundary conditions were obtained. Numerical solutions were given to investigate the influencing mechanism of surface elasticity, surface piezoelectricity, surface dielectricity, as well as the surface density upon the propagation characteristics of SH surface waves, respectively. The results also reveal the size-dependence of dispersive behaviors, which indicates that the surface effects make a difference only when the thickness of the piezoelectric nanofilm stays in a certain range.
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Sakhaee-Pour, A., M. T. Ahmadian i A. Gerami. "Development of an equation to predict radial modulus of elasticity for single-walled carbon nanotubes". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, nr 6 (1.06.2008): 1109–15. http://dx.doi.org/10.1243/09544062jmes751.
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Finite element (FE) method is used to model radial deformation of single-walled carbon nanotube (SWCNT) under hydrostatic pressure. Elastic deformation of the nanostructure is simulated via elastic beams. Properties of the beam element are calculated by considering the stiffness of the covalent bonds between the carbon atoms in the hexagonal lattice. By applying the beam elements in a three-dimensional space, elastic properties of the SWCNT in transverse direction are obtained. In this regard, influences of diameter and tube wall thickness on the radial and circumferential elastic moduli of zigzag and armchair SWCNTs are considered. It is observed that there is a good agreement between the FE results and data available in the literatures. The FE data are employed to develop a predictive equation through a statistical non-linear regression model.
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Arefi, M., MH Zamani i M. Kiani. "Smart electrical and magnetic stability analysis of exponentially graded shear deformable three-layered nanoplate based on nonlocal piezo-magneto-elasticity theory". Journal of Sandwich Structures & Materials 22, nr 3 (28.02.2018): 599–625. http://dx.doi.org/10.1177/1099636218760667.
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The present research deals with magnetic and electric buckling loads of three-layered elastic nanoplate with exponentially graded core and piezomagnetic face-sheets. Material properties of the nano-graphene core obey the exponential function along the thickness direction. The governing equations based on first-order shear deformation theory are deduced using variational method. The influence of nanoscale is considered by employing nonlocal piezo-magneto-elasticity theory. The governing equations of nanostructure are solved analytically. Eventually the effect of significant parameters such as length-scale parameter, in-homogenous index, geometrical characteristics and parameters of foundation on the magneto-electro responses of problem is numerically investigated.
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Le, Minh Tai, i Shyh Chour Huang. "Modeling and Analysis the Effect of Helical Carbon Nanotube Morphology on the Mechanical Properties of Nanocomposites Using Hexagonal Representative Volume Element". Applied Mechanics and Materials 577 (lipiec 2014): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amm.577.3.
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Carbon nanotubes (CNTs) are the ultimate reinforcing materials for the development of an entirely new class of composites. However, they have the complicated shapes and do not usually appear as straight reinforcements when introduced in polymer matrices. This decreases nanotube’s effectiveness in enhancing the matrix mechanical properties. In this paper, nanostructure having hexagonal representative volume element (RVE), theory of elasticity of anisotropic materials and finite element method (FEM) are used to investigate the effect of helical CNT morphology on effective mechanical properties of nanocomposites. CNT with different helical angles are modeled to estimate the nanocomposite mechanical properties. The results of helical nanotube models are compared with the effective mechanical properties of nanocomposites reinforced with straight nanotubes.
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Ti, C., J. G. McDaniel, A. Liem, H. Gress, M. Ma, S. Kyoung, O. Svitelskiy i in. "Dynamics of NEMS resonators across dissipation limits". Applied Physics Letters 121, nr 2 (11.07.2022): 023506. http://dx.doi.org/10.1063/5.0100318.
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The oscillatory dynamics of nanoelectromechanical systems (NEMS) is at the heart of many emerging applications in nanotechnology. For common NEMS, such as beams and strings, the oscillatory dynamics is formulated using a dissipationless wave equation derived from elasticity. Under a harmonic ansatz, the wave equation gives an undamped free vibration equation; solving this equation with the proper boundary conditions provides the undamped eigenfunctions with the familiar standing wave patterns. Any harmonically driven solution is expressible in terms of these undamped eigenfunctions. Here, we show that this formalism becomes inconvenient as dissipation increases. To this end, we experimentally map out the position- and frequency-dependent oscillatory motion of a NEMS string resonator driven linearly by a non-symmetric force at one end at different dissipation limits. At low dissipation (high Q factor), we observe sharp resonances with standing wave patterns that closely match the eigenfunctions of an undamped string. With a slight increase in dissipation, the standing wave patterns become lost, and waves begin to propagate along the nanostructure. At large dissipation (low Q factor), these propagating waves become strongly attenuated and display little, if any, resemblance to the undamped string eigenfunctions. A more efficient and intuitive description of the oscillatory dynamics of a NEMS resonator can be obtained by superposition of waves propagating along the nanostructure.
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Kot, Marcin, Tomasz Moskalewicz, Bogdan Wendler, Aleksandra Czyrska-Filemonowicz i Wiesław Rakowski. "Micromechanical and Tribological Properties of Nanocomposite nc-TiC/a-C Coatings". Solid State Phenomena 177 (lipiec 2011): 36–46. http://dx.doi.org/10.4028/www.scientific.net/ssp.177.36.
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The nanocomposite coatings composed of nanocrystalline TiC grains embedded in hydrogen free amorphous carbon a-C matrix (nc-TiC/a-C) were deposited by magnetron sputtering on the two substrates, oxygen hardened Ti-6Al-4V alloy and heat treated VANADIS 23 steel. The Ti-6Al-4V alloy was oxygen hardened by plasma glow discharge. Micro-mechanical and tribological properties as well as coating adhesion to the substrates were investigated. Micro/nanostructure of the coatings and the substrates were examined using scanning- and transmission electron microscopy methods as well as X-ray diffractometry. Nano-, microhardness tests performed for the coated materials showed average hardness 13.4-14.7 GPa and modulus of elasticity 160 GPa. Scratch test revealed good adhesion of coatings to the both substrates. The nanocomposite coatings significantly improved tribological properties of the titanium alloy and steel, increased wear resistance and decreased friction coefficient.
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Keivani, M., A. Koochi i M. Abadyan. "A New Bilayer Continuum Model Based on Gurtin-Murdoch and Consistent Couple-Stress Theories for Stability Analysis of Beam-Type Nanotweezers". Journal of Mechanics 33, nr 2 (1.07.2016): 137–46. http://dx.doi.org/10.1017/jmech.2016.45.
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AbstractNano-scale beams might not be considered uniform isotropic since the energy of the surface layer and microstructure of the bulk part highly affect the mechanical characteristics of the beams. Herein, the impact of the energy of the surface layer and the microstructure of the bulk on the mechanical stability of beam-type nanotweezers are investigated. A new bilayer continuum model has been developed which incorporates the strain energy of the surface atoms as well as the microstructure-dependent strain energy of the bulk material. The recently-developed consistent couple stress elasticity (CCSE) in combination with the Gurtin-Murdoch surface theory is applied to derive the governing equation. The nonlinear governing equation was solved using numerical generalized differential quadrature (GDQ). Effects of various parameters including characteristics of the surface layer, microstructure of the bulk and external forces on the static and dynamic stability threshold of the nanostructure are demonstrated.
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Javanbakht, Mahdi, Mohammad Sadegh Ghaedi, Emilio Barchiesi i Alessandro Ciallella. "The effect of a pre-existing nanovoid on martensite formation and interface propagation: a phase field study". Mathematics and Mechanics of Solids 26, nr 1 (6.08.2020): 90–109. http://dx.doi.org/10.1177/1081286520948118.
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In the present work, the effect of a pre-existing nanovoid on martensitic phase transformation (PT) is investigated using the phase field approach. The nanovoid is created as a solution of the coupled Cahn–Hilliard and elasticity equations. The coupled Ginzburg–Landau and elasticity equations are solved to capture the martensitic nanostructure. The above systems of equations are solved using the finite element method and COMSOL code. The austenite ( A)–martensite ( M) interface propagation is investigated without the nanovoid and with it for different nanovoid misfit strains and different temperatures. With the nanovoid, the evolution of the moving interface is changed even before it reaches the nanovoid surface due to the nanovoid stress concentration. It is also found that for small misfit strains, pre-transformation occurs near the nanovoid. For larger misfit strains, martensite nucleates and grows near the nanovoid surface and coalesces with the moving interface. The nanovoid shows a promotive effect on the PT with an increase in the rate of transformation, which is discussed based on the transformation work distribution. The effect of the nanovoid is more pronounced on a curved interface. The nanovoid-induced martensitic growth is mainly dependent on the transformation strain tensor. Examples for different transformation strains are presented where a stable non-complete transformed sample with no void becomes unstable in the presence of the nanovoid. The presented model and results will help to develop an interaction model between nanovoids and multiphase structures at the nanoscale.
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Yeo, Giselle C., Anna Tarakanova, Clair Baldock, Steven G. Wise, Markus J. Buehler i Anthony S. Weiss. "Subtle balance of tropoelastin molecular shape and flexibility regulates dynamics and hierarchical assembly". Science Advances 2, nr 2 (5.02.2016): e1501145. http://dx.doi.org/10.1126/sciadv.1501145.
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The assembly of the tropoelastin monomer into elastin is vital for conferring elasticity on blood vessels, skin, and lungs. Tropoelastin has dual needs for flexibility and structure in self-assembly. We explore the structure-dynamics-function interplay, consider the duality of molecular order and disorder, and identify equally significant functional contributions by local and global structures. To study these organizational stratifications, we perturb a key hinge region by expressing an exon that is universally spliced out in human tropoelastins. We find a herniated nanostructure with a displaced C terminus and explain by molecular modeling that flexible helices are replaced with substantial β sheets. We see atypical higher-order cross-linking and inefficient assembly into discontinuous, thick elastic fibers. We explain this dysfunction by correlating local and global structural effects with changes in the molecule’s assembly dynamics. This work has general implications for our understanding of elastomeric proteins, which balance disordered regions with defined structural modules at multiple scales for functional assembly.
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Polonina, Elena, Olaf Lahayne, Josef Eberhardsteiner i Sergey Leonovich. "Nanoindentation of cement stone samples". E3S Web of Conferences 212 (2020): 02013. http://dx.doi.org/10.1051/e3sconf/202021202013.
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The preliminary results of the studied cement samples were obtained by the nanoindentation method. It was revealed that the elastic modulus M increases in samples that contain a complex additive containing nanosized particles. The effect is also observed with the introduction of an additive containing only one type of nanoparticles (nanosilica sol SiO2 or carbon nanomaterial MCNT). The selection of the parameters of the nanoindentation method, which ensured the obtaining of the final consistent results, was performed. These results are presented by histograms of the distribution of nanoindentation points in modulus of elasticity M and hardness H and distributions in M and H in the horizontal XY plane perpendicular to the motion of the nanoindentor. The results obtained indicate that there is a change in the nanostructure of the C – S – H gel, which is compared with an increase in strength, Young’s moduli and shear, upon the introduction of SiO2 nanoparticles and MCNT nanoparticles.
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Lopez-Sanchez, Patricia, Ali Assifaoui, Fabrice Cousin, Josefine Moser, Mauricio R. Bonilla i Anna Ström. "Impact of Glucose on the Nanostructure and Mechanical Properties of Calcium-Alginate Hydrogels". Gels 8, nr 2 (22.01.2022): 71. http://dx.doi.org/10.3390/gels8020071.
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Alginate is a polysaccharide obtained from brown seaweed that is widely used in food, pharmaceutical, and biotechnological applications due to its versatility as a viscosifier and gelling agent. Here, we investigated the influence of the addition of glucose on the structure and mechanical properties of alginate solutions and calcium-alginate hydrogels produced by internal gelation through crosslinking with Ca2+. Using 1H low-field nuclear magnetic resonance (NMR) and small angle neutron scattering (SANS), we showed that alginate solutions at 1 wt % present structural heterogeneities at local scale whose size increases with glucose concentration (15–45 wt %). Remarkably, the molecular conformation of alginate in the gels obtained from internal gelation by Ca2+ crosslinking is similar to that found in solution. The mechanical properties of the gels evidence an increase in gel strength and elasticity upon the addition of glucose. The fitting of mechanical properties to a poroelastic model shows that structural changes within solutions prior to gelation and the increase in solvent viscosity contribute to the gel strength. The nanostructure of the gels (at local scale, i.e., up to few hundreds of Å) remains unaltered by the presence of glucose up to 30 wt %. At 45 wt %, the permeability obtained by the poroelastic model decreases, and the Young’s modulus increases. We suggest that macro (rather than micro) structural changes lead to this behavior due to the creation of a network of denser zones of chains at 45 wt % glucose. Our study paves the way for the design of calcium-alginate hydrogels with controlled structure for food and pharmaceutical applications in which interactions with glucose are of relevance.
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Vilaça, Helena, André Carvalho, Tarsila Castro, Elisabete M. S. Castanheira, Loic Hilliou, Ian Hamley, Manuel Melle-Franco, Paula M. T. Ferreira i José A. Martins. "Unveiling the Role of Capping Groups in Naphthalene N-Capped Dehydrodipeptide Hydrogels". Gels 9, nr 6 (6.06.2023): 464. http://dx.doi.org/10.3390/gels9060464.
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Self-assembled peptide-based hydrogels are archetypical nanostructured materials with a plethora of foreseeable applications in nanomedicine and as biomaterials. N-protected di- and tri-peptides are effective minimalist (molecular) hydrogelators. Independent variation of the capping group, peptide sequence and side chain modifications allows a wide chemical space to be explored and hydrogel properties to be tuned. In this work, we report the synthesis of a focused library of dehydrodipeptides N-protected with 1-naphthoyl and 2-naphthylacetyl groups. The 2-naphthylacetyl group was extensively reported for preparation of peptide-based self-assembled hydrogels, whereas the 1-naphthaloyl group was largely overlooked, owing presumably to the lack of a methylene linker between the naphthalene aromatic ring and the peptide backbone. Interestingly, dehydrodipeptides N-capped with the 1-naphthyl moiety afford stronger gels, at lower concentrations, than the 2-naphthylacetyl-capped dehydrodipeptides. Fluorescence and circular dichroism spectroscopy showed that the self-assembly of the dehydrodipeptides is driven by intermolecular aromatic π–π stacking interactions. Molecular dynamics simulations revealed that the 1-naphthoyl group allows higher order aromatic π–π stacking of the peptide molecules than the 2-naphthylacetyl group, together with hydrogen bonding of the peptide scaffold. The nanostructure of the gel networks was studied by TEM and STEM microscopy and was found to correlate well with the elasticity of the gels. This study contributes to understanding the interplay between peptide and capping group structure on the formation of self-assembled low-molecular-weight peptide hydrogels. Moreover, the results presented here add the 1-naphthoyl group to the palette of capping groups available for the preparation of efficacious low-molecular-weight peptide-based hydrogels.
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Li, Yan, Mingzhu Yao, Chen Liang, Hui Zhao, Yang Liu i Yifeng Zong. "Hemicellulose and Nano/Microfibrils Improving the Pliability and Hydrophobic Properties of Cellulose Film by Interstitial Filling and Forming Micro/Nanostructure". Polymers 14, nr 7 (23.03.2022): 1297. http://dx.doi.org/10.3390/polym14071297.
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In this paper, nano/microfibrils were applied to enhance the mechanical and hydrophobic properties of the sugarcane bagasse fiber films. The successful preparation of nano/microfibrils was confirmed by scanning electron microscope (SEM), X-ray diffraction (XRD), fiber length analyzer (FLA), and ion chromatography (IC). The transparency, morphology, mechanical and hydrophobic properties of the cellulose films were evaluated. The results show that the nanoparticle was formed by the hemicellulose diffusing on the surface of the cellulose and agglomerating in the film-forming process at 40 °C. The elastic modulus of the cellulose film was as high as 4140.60 MPa, and the water contact angle was increased to 113°. The micro/nanostructures were formed due to hemicellulose adsorption on nano/microfilament surfaces. The hydrophobicity of the films was improved. The directional crystallization of nano/microfibrous molecules was found. Cellulose films with a high elastic modulus and high elasticity were obtained. It provides theoretical support for the preparation of high-performance cellulose film.
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Emel’yanov, V. I. "The 3D Kuramoto-Sivashinsky Equation for Nonequilibrium Defects Interacting through Self-Consisting Strain and Nanostructuring of Solids". ISRN Nanomaterials 2013 (21.10.2013): 1–6. http://dx.doi.org/10.1155/2013/981616.
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It is shown that the bulk defect-deformational (DD) nanostructuring of isotropic solids can be described by a closed three-dimensional (3D) nonlinear DD equation of the Kuramoto-Sivashinsry (KS) type for the nonequilibrium defect concentration, derived here in the framework of the nonlocal elasticity theory (NET). The solution to the linearized DDKS equation describes the threshold appearance of the periodic self-consistent strain modulation accompanied by the simultaneous formation of defect piles at extremes of the strain. The period and growth rate of DD nanostructure are determined. Based on the obtained results, a novel mechanism of nanostructuring of solids under the severe plastic deformation (SPD), stressing the role of defects generation and selforganization, described by the DDKS, is proposed. Theoretical dependencies of nanograin size on temperature and shear strain reproduce well corresponding critical dependencies obtained in experiments on nanostructuring of metals under the SPD, including the effect of saturation of nanofragmentation. The scaling parameter of the NET is estimated and shown to determine the limiting small grain size.
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Li, Cheng, C. W. Lim i Zhong Kui Zhu. "Vibration Analysis of Axially Compressed Nanobeams and its Critical Pressure Using a New Nonlocal Stress Theory". Applied Mechanics and Materials 105-107 (wrzesień 2011): 1788–92. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1788.
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The transverse vibration of a nanobeam subject to initial axial compressive forces based on nonlocal elasticity theory is investigated. The effects of a small nanoscale parameter at molecular level unavailable in classical mechanics theory are presented and analyzed. Explicit solutions for natural frequency, vibration mode shapes are derived through two different methods: separation of variables and multiple scales. The respective numerical solutions are in close agreement. Validity of the models and approaches presented in the work are verified. Unlike the previous studies for a nonlocal nanostructure, this paper adopts the effective nonlocal bending moment instead of the pure traditional nonlocal bending moment. The analysis yields an infinite-order differential equation of motion which governs the vibrational behaviors. For practical analysis and as examples, an eight-order governing differential equation of motion is solved and the results are discussed. The paper presents a complete nonlocal nanobeam model and the results may be helpful for the application and design of various nano-electro-mechanical devices, e.g. nano-drivers, nano-oscillators, nano-sensors, etc., where a nanobeam acts as a basic element.
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Batyuk, Liliya, i Natalya Kizilova. "Rheological models of biological cells". Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, nr 2 (2022): 37–41. http://dx.doi.org/10.17721/1812-5409.2022/2.4.
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The most important experimental methods of studying the mechanical properties of cells, as well as the most common rheological models, among which the discrete models of the micro/nanostructure of the cell and continuous models that allow calculating the modulus of elasticity and viscosity of the cell in normal and pathological conditions are discussed. A review of continuous models is given with an indication of their features and differences. A new continuum model of the cell as a multi-layer shell filled with a viscoelastic fluid is proposed. Equations of the model and their solutions for cases of isotonic, isometric and dynamic experiments are obtained. Peculiarities of the mechanical behavior of the models depending on the identified parameters are investigated. A comparison with the data of experimental measurements is given. It is shown that the proposed multi-layer model allows evaluation of separate contribution of the mechanical properties of the cytoskeleton, membrane, adsorbed substances and the hydrated shell, which is important for clinical diagnosis of diseases by measuring the mechanical parameters of cells.
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Jankowski, Piotr. "On the Nonlocal Interaction Range for Stability of Nanobeams with Nonlinear Distribution of Material Properties". Acta Mechanica et Automatica 16, nr 2 (18.04.2022): 151–61. http://dx.doi.org/10.2478/ama-2022-0019.
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Abstract The present study analyses the range of nonlocal parameters’ interaction on the buckling behaviour of nanobeam. The intelligent nonhomogeneous nanobeam is modelled as a symmetric functionally graded (FG) core with porosity cause nonlinear distribution of material parameters. The orthotropic face-sheets are made of piezoelectric materials. These kinds of structures are widely used in nanoelectromechanical systems (NEMS). The nanostructure model satisfies the assumptions of Reddy third-order beam theory and higher-order nonlocal elasticity and strain gradient theory. This approach allows to predict appropriate mechanical response of the nanobeam regardless of thin or thick structure, in addition to including nano-sized effects as hardening and softening. The analysis provided in the present study focuses on differences in results for nanobeam stability obtained based on classical and nonlocal theories. The study includes the effect of diverse size-dependent parameters, nanobeams’ length-to-thickness ratio and distributions of porosity and material properties through the core thickness as well as external electro-mechanical loading. The results show a dependence of nonlocal interaction range on geometrical and material parameters of nanobeam. The investigation undertaken in the present study provides an interpretation for this phenomenon, and thus aids in increasing awareness of nanoscale structures’ mechanical behaviour.
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Ghaedi, Mohammad Sadegh, i Mahdi Javanbakht. "Effect of a thermodynamically consistent interface stress on thermal-induced nanovoid evolution in NiAl". Mathematics and Mechanics of Solids 26, nr 9 (18.01.2021): 1320–36. http://dx.doi.org/10.1177/1081286520986603.
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In the present work, the effect of a thermodynamically consistent inelastic interface stress on nanovoid evolution in NiAl is studied. Such interface stress is introduced for the solid–gas interface of nanovoids within the concept of the phase field approach. The Cahn–Hilliard (CH) equation using the Helmholtz free energy describes the evolution of nanovoid concentration. The interface stress changes the total stress distribution and affects the elastic stress field. Thus, due to the significant effect of the elastic energy on nanovoid dynamics, it can indirectly affect nanovoid nucleation and growth. The highly nonlinear coupled CH and elasticity equations are solved using the finite element method and the COMSOL code. The coupling appears due to the presence of the nonlinear nanovoid inelastic strain in the total strain, the presence of the nonlinear inelastic interface stress in the stress tensor and the presence of elastic energy in the Helmholtz free energy. Several examples of thermal-induced nanovoid evolutions are presented to investigate the effect of the solid–gas interface stress. The obtained results show the significant effect of the interface stress on the total stress distribution, and consequently a different distribution of thermodynamic driving force which can affect the nanostructure evolution and the deformation. Mainly, the interface stress represents a promotive effect on nanovoid growth which results in a faster nanovoid growth and a larger nanovoid concentration and region.
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M Sobamowo, Gbeminiyi, Olorunfemi O Isaac, Suraju A Oladosu i Rafiu O Kuku. "On the dynamic behaviour of carbon nanotubes conveying fluid resting on elastic foundations in a magnetic-thermal environment: effects of surface energy and initial stress". Aeronautics and Aerospace Open Access Journal 7, nr 1 (4.04.2023): 26–34. http://dx.doi.org/10.15406/aaoaj.2023.07.00167.
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In this article, simultaneous impacts of surface elasticity, initial stress, residual surface tension and nonlocality on the nonlinear vibration of single-walled carbon conveying nanotube resting on linear and nonlinear elastic foundation and operating in a thermo-magnetic environment are studied. The developed equation of motion is solved using Galerkin’s decomposition and Temini and Ansari method. The studies of the impacts of various parameters on the vibration problems revealed that the ratio of the nonlinear to linear frequencies increases with the negative value of the surface stress while it decreases with the positive value of the surface stress. The surface effect reduces for increasing in the length of the nanotube. Ratio of the frequencies decreases with increase in the strength of the magnetic field, nonlocal parameter and the length of the nanotube. Increase in temperature change at high temperature causes decrease in the frequency ratio. However, at room or low temperature, the frequency ratio of the hybrid nanostructure increases as the temperature change increases. The natural frequency of the nanotube gradually approaches the nonlinear Euler–Bernoulli beam limit at high values of nonlocal parameter and nanotube length. Nonlocal parameter reduces the surface effects on the ratio of the frequencies. Also, the ratio of the frequencies at low temperatures is lower than at high temperatures. It is hoped that the present work will enhance the control and design of carbon nanotubes operating in thermo-magnetic environment and resting on elastic foundations.
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Shilov, М. А., S. V. Fomin, A. A. Britova i P. V. Korolev. "Investigation of Physical and Mechanical Properties of Rubbers Reinforced by Carbon Nanostructured Components". Liquid Crystals and their Application 20, nr 4 (29.12.2020): 93–98. http://dx.doi.org/10.18083/lcappl.2020.4.93.
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The work presents investigation results of physical and mechanical properties of rubber mixtures based on SKI-3 and SKS-30-ARKM-15 rubbers reinforced with hybrid filler carbon black/carbon nanotubes (CB/CNT). Elasticity, hardness and strength were measured according to standard procedures presented in GOST. The content of the carbon nanotubes in rubber mixtures was 0,5 wt. %. parts per 100 wt. parts of rubber. According to experiments, it was found that the introduction of CB/CNT masterbatches into the structure of both investigated rubbers reduces their elasticity and increases Shore A hardness. During uniaxial tension of the tested rubbers, it was found that the presence of the nanostructured CB/CNT filler in the rubber structure leads to an increase in the nominal strength for SKI-3-based rubber by 19,6 %, and on SKS-30-ARKM-15 by 22,5 %. Therefore, the use of CB/CNT nanostructures as a rubber filler is a promising method of improving rubber performance characteristics.
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Colombo, Luciano, i Stefano Giordano. "Nonlinear elasticity in nanostructured materials". Reports on Progress in Physics 74, nr 11 (14.10.2011): 116501. http://dx.doi.org/10.1088/0034-4885/74/11/116501.
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Duan, Jingbo, Dapeng Zhang i Wenjie Wang. "Flutter and Divergence Instability of Axially-Moving Nanoplates Resting on a Viscoelastic Foundation". Applied Sciences 9, nr 6 (15.03.2019): 1097. http://dx.doi.org/10.3390/app9061097.
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Moving nanosystems often rest on a medium exhibiting viscoelastic behavior in engineering applications. The moving velocity and viscoelastic parameters of the medium usually have an interacting impact on the mechanical properties of nanostructures. This paper investigates the dynamic stability of an axially-moving nanoplate resting on a viscoelastic foundation based on the nonlocal elasticity theory. Firstly, the governing partial equations subject to appropriate boundary conditions are derived through utilizing the Hamilton’s principle with the axial velocity, viscoelastic foundation, nonlocal effect and biaxial loadings taken into consideration. Subsequently, the characteristic equation describing the dynamic characteristics is obtained by employing the Galerkin strip distributed transfer function method. Then, complex frequency curves for the nanoplate are displayed graphically and the effects of viscoelastic foundation parameters, small-scale parameters and axial forces on divergence instability and coupled-mode flutter are analyzed, which show that these parameters play a crucial role in affecting nanostructural instability. The presented results benefit the designation of axially-moving graphene nanosheets or other plate-like nanostructures resting on a viscoelastic foundation.
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Sherstyukova, E. A., V. A. Inozemtsev, A. P. Kozlov, O. E. Gudkova i V. A. Sergunova. "Atomic force microscopy in the assessment of erythrocyte membrane mechanical properties with exposure to various physicochemical agents". Almanac of Clinical Medicine 49, nr 6 (8.12.2021): 427–34. http://dx.doi.org/10.18786/2072-0505-2021-49-059.
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Background: Mechanical properties of cell membranes and their structural organization are considered among the most important biological parameters affecting the functional state of the cell. Under the influence of various pathogenic factors, erythrocyte membranes lose their elasticity. The resulting changes in their biomechanical characteristics is an important, but poorly studied topic. It is of interest to study the deformation of native erythrocytes to a depth compatible with their deformation in the bloodstream.Aim: To investigate the patterns of deep deformation and the particulars of structural organization of native erythrocyte membranes before and after their exposure to physicochemical agents in vitro.Materials and methods: Cell morphology, nanostructure characteristics, and membrane deformation of native erythrocytes in a solution of hemoconservative CPD/SAGM were studied with atomic force microscope NTEGRA Prima. Hemin, zinc ions (Zn2+), and ultraviolet (UV) radiation were used as modifiers. To characterize the membrane stiffness, we measured the force curves F(h), hHz (the depth to which the probe immersion is described by interaction with a homogeneous medium), and the Young's modulus values of the erythrocyte membrane.Results: Exposure to hemin, Zn2+ and UV radiation led to transformation of the cell shape, appearance of topological defects and changes in mechanical characteristics of erythrocyte membranes. Under exposure to hemin, Young's modulus increased from 10±4 kPa to 27.2±8.6 kPa (p<0.001), exposure to Zn2+, to 21.4±8.7 kPa (p=0.002), and UV, to 18.8±5.6 kPa (p=0.001). The hHz value was 815±210 nm for the control image and decreased under exposure to hemin to 420±80 nm (p<0.001), Zn2+, to 370±90 nm (p<0.001), and UV, to 614±120 nm (p=0.001).Conclusion: The results obtained contribute to a deeper understanding of interaction between membrane surfaces of native erythrocytes and small vessel walls. They can be useful in clinical medicine as additional characteristics for assessment of the quality of packed red blood cells, as well as serve as a basis for biophysical studies into the mechanisms of action of oxidative processes of various origins.
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Mizubayashi, H., K. Fujita, K. Fujiwara i H. Tanimoto. "Elasticity Study of Nanostructured Copper Thin Films". Journal of Metastable and Nanocrystalline Materials 24-25 (wrzesień 2005): 61–64. http://dx.doi.org/10.4028/www.scientific.net/jmnm.24-25.61.
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Sambani, Kyriaki, Stylianos Vasileios Kontomaris i Dido Yova. "Atomic Force Microscopy Imaging of Elastin Nanofibers Self-Assembly". Materials 16, nr 12 (11.06.2023): 4313. http://dx.doi.org/10.3390/ma16124313.
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Elastin is an extracellular matrix protein, providing elasticity to the organs, such as skin, blood vessels, lungs and elastic ligaments, presenting self-assembling ability to form elastic fibers. The elastin protein, as a component of elastin fibers, is one of the major proteins found in connective tissue and is responsible for the elasticity of tissues. It provides resilience to the human body, assembled as a continuous mesh of fibers that require to be deformed repetitively and reversibly. Thus, it is of great importance to investigate the development of the nanostructural surface of elastin-based biomaterials. The purpose of this research was to image the self-assembling process of elastin fiber structure under different experimental parameters such as suspension medium, elastin concentration, temperature of stock suspension and time interval after the preparation of the stock suspension. atomic force microscopy (AFM) was applied in order to investigate how different experimental parameters affected fiber development and morphology. The results demonstrated that through altering a number of experimental parameters, it was possible to affect the self-assembly procedure of elastin fibers from nanofibers and the formation of elastin nanostructured mesh consisting of naturally occurring fibers. Further clarification of the contribution of different parameters on fibril formation will enable the design and control of elastin-based nanobiomaterials with predetermined characteristics.
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Naskar, Supriyo, i Prabal K. Maiti. "Mechanical properties of DNA and DNA nanostructures: comparison of atomistic, Martini and oxDNA models". Journal of Materials Chemistry B 9, nr 25 (2021): 5102–13. http://dx.doi.org/10.1039/d0tb02970j.
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Bull, S. J. "Nanomechanics of Coatings for Electronic and Optical Applications". Solid State Phenomena 159 (styczeń 2010): 11–18. http://dx.doi.org/10.4028/www.scientific.net/ssp.159.11.
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In most coating applications damage resistance is controlled by the mechanical properties of the coating, interface and substrate. For electronic and optical applications the design of coating-substrate systems has been predominantly controlled by their functional properties but more recently the mechanical response of the system has been used to enhance functional properties, as in the case of strained silicon/SiGe microelectronic devices where tensile strain has been used to enhance mobility and increase device speed. As coatings become more complex, with multilayer and graded architectures now in widespread use, it is very important to obtain the mechanical properties (such as hardness, elastic modulus, fracture toughness, etc.) of individual coating layers for use in design calculations and have failure-related design criteria which are valid for such multilayer systems. Nanoindentation testing is often the only viable approach to assess the damage mechanisms and properties of very thin coatings (<m) since it can operate at the required scale and provides fingerprint of the indentation response of the coating/substrate system. If coating properties are to be assessed, the key point is to ensure any measured value is free from the influence of the deforma-tion of the substrate or lower coating layers. Finite element analysis of indentation load displace-ment curves can be used to extract materials properties for design; as coating thicknesses decrease it is observed that the yield strength required to fit the curves increases and scale-dependent materials properties are essential for design. Since plasticity is less likely, non-linear elasticity is increasingly important as the size of a nanostructure is reduced. Similarly the assessment of fracture response of very thin coatings requires modeling of the indentation stress field and how it is modified by plas-ticity during the indentation cycle. An FE approach using a cohesive zone model has been used to assess the locus of failure and demonstrates the complexity of adhesive failure around indentations for multilayer coatings. Finally the mechanical design of a metallization stress sensor based on na-noindentation-derived materials properties, non-linear elastic and plastic behavior and the treatment of geometrical non-linearities (stress stiffening) is discussed.
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Barretta, Raffaele, Francesco Marotti de Sciarra i Marzia Sara Vaccaro. "Nonlocal Elasticity for Nanostructures: A Review of Recent Achievements". Encyclopedia 3, nr 1 (27.02.2023): 279–310. http://dx.doi.org/10.3390/encyclopedia3010018.
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Recent developments in modeling and analysis of nanostructures are illustrated and discussed in this paper. Starting with the early theories of nonlocal elastic continua, a thorough investigation of continuum nano-mechanics is provided. Two-phase local/nonlocal models are shown as possible theories to recover consistency of the strain-driven purely integral theory, provided that the mixture parameter is not vanishing. Ground-breaking nonlocal methodologies based on the well-posed stress-driven formulation are shown and commented upon as effective strategies to capture scale-dependent mechanical behaviors. Static and dynamic problems of nanostructures are investigated, ranging from higher-order and curved nanobeams to nanoplates. Geometrically nonlinear problems of small-scale inflected structures undergoing large configuration changes are addressed in the framework of integral elasticity. Nonlocal methodologies for modeling and analysis of structural assemblages as well as of nanobeams laying on nanofoundations are illustrated along with benchmark applicative examples.
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Belyaev, Leonid V., Aleksey V. Zhdanov i Valentin V. Morozov. "Application of the Nanostructured Carbon Coatings for Improvement of Functional Properties of Medical Polyurethanes". Advanced Materials Research 1088 (luty 2015): 3–7. http://dx.doi.org/10.4028/www.scientific.net/amr.1088.3.
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Results of researches of structure and properties of the nanostructured carbon coatings deposited on a polyurethane substrate are presented in article. Possibility of application of the scanning probe microscope methods and sklerometry for quality control of the nanostructured carbon coatings is shown. The results of researches showing are given that the nanostructured carbon coatings deposited on polyurethane have high degree of adhesion to a substrate, reduce porosity of surface and increase its durability and wear resistance, increase elasticity and coefficient of elastic restoration at deformation.
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Li, Cheng, i Wei Guo Huang. "Nonlocal Size Dependence of a Softness Nanobeam with Large Axial Tension under Various Boundary Conditions". Advanced Materials Research 490-495 (marzec 2012): 3226–30. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.3226.
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The transverse dynamical behaviors of softness Euler-Bernoulli nanobeams subjected to a biggish initial axial force based on nonlocal elasticity theory are investigated in this paper. The size-dependent theory is considered and a small intrinsic length scale parameter unavailable in classical continuum mechanics is adopted into the problem model as a size parameter. The linear partial differential governing equation is derived from the Newton’s second law and the ordinary equation and its dispersion relation are gained from by the method of separation of variables. Five sets of supporting conditions are presented respectively including simply supported, fully clamped, flexible fixed ends, sliding supports ends and completely free ends. Vibration frequencies are obtained approximately and correlations between the natural frequency and the dimensionless small scale parameter are also analyzed and discussed in detail. It shows that an increase in small scale parameter and dimensionless initial axial tension causes natural frequency to increase, while an increase in the dimensionless stiffness of nanostructures causes natural frequency to decrease, or the nanostructural bending stiffness is enhanced when nonlocal effects are considered.
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Dolbin, Igor V., Gusein M. Magomedov i Georgii V. Kozlov. "The Influence of Phases Division Surface in Nanocomposites Polymer/2D-Nanofiller on their Reinforcement Degree - The Percolation Model". Key Engineering Materials 869 (październik 2020): 516–23. http://dx.doi.org/10.4028/www.scientific.net/kem.869.516.
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The simple percolation model, in which critical indices are defined by the form of a reinforcing component of nanostructured composite structure, was proposed for the description of reinforcement degree for nanostructured composites polymer/2D-nanofiller. The indicated critical indices are close by absolute values to standard percolation indices. The form of reinforcing component controls the type of nanostructured composite. It has been shown that reinforcement degree of these nanomaterials is independent on modulus of elasticity of nanofiller, but is defined by its structure (aggregation level), created in polymer matrix. The percolation indices of a percolation model, which are due to the form of reinforcing component and nanocomposite type, are defined by its main characteristic – the fraction of phases division surface in overall sample volume and are the basic factor, controlling reinforcement degree of nanostructured composites.
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Roca, Antoni, Jordi Llumà, Jordi Jorba i Núria Llorca-Isern. "Measurement of Elastic Constants on Nanostructured Iron and Copper". Materials Science Forum 638-642 (styczeń 2010): 1772–77. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1772.
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Measurements of the elasticity modulus and Poisson’s ratio on nanostructured iron obtained by mechanical milling and on nanostructured copper obtained by severe plastic deformation (ECAP) have been carried out. Iron powder was severely deformed in a planetary ball milling. Powder compaction was done in a testing machine, obtaining cylinders that were compacted at temperatures between 425°C and 500°C. Commercial Cu of 99.98 wt % purity was processed at room temperature by Equal-Channel Angular Pressing (ECAP) following the route Bc. Heavy deformation was introduced in the samples after a considerable number of ECAP passes, from 1 to 16. A significant grain refinement was observed after processing the samples. The most important microstructural and mechanical changes were introduced in the first ECAP pass. Elasticity modulus and Poisson’s ratio were determined in iron and copper samples by ultrasonic measurement using an ultrasonic pulser-receiver and two transducers appropriate to the tested materials for pulse-echo sound velocity measurement in longitudinal and shear modes.
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Petryk, Ivan, Yuriy Lutsiuk i Valeriy Kramar. "Frequency spectrum and group velocities of acoustic phonons in PbI2 nanofilms". Physics and Chemistry of Solid State 23, nr 3 (24.08.2022): 478–83. http://dx.doi.org/10.15330/pcss.23.3.478-483.
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Using the elastic continuum approach, an energy spectrum and spectral dependences of a group velocities of confined acoustic phonons in planar quasi-two-dimensional nanostructures (nanofilms) of hexagonal symmetry of the 2H-PbI2 type were studied by methods of the theory of elasticity. It is shown that the energy and propagation velocity of vibrational modes for all branches of the phonon spectrum in these type nanostructures are nonlinear functions of a magnitude of a wave vector and a thickness of the nanofilm. The obtained results can be used to analyze an influence of acoustic phonons on a course of phenomena of thermal and electrical conductivity, carrier scattering and optical absorption in nanostructures, components of which are thin layers of lead iodide.
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Kabe, Yoshio, Hisanori Tanimoto i Hiroshi Mizubayashi. "Elasticity Study of Nanostructured Al and Al-Si(Cu) Films". MATERIALS TRANSACTIONS 45, nr 1 (2004): 119–24. http://dx.doi.org/10.2320/matertrans.45.119.
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Di Lorenzo, F., i S. Seiffert. "Nanostructural heterogeneity in polymer networks and gels". Polymer Chemistry 6, nr 31 (2015): 5515–28. http://dx.doi.org/10.1039/c4py01677g.
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Many polymer gels display network defects and crosslinking inhomogeneity. This review reflects and interrelates investigations on the characterization of such polymer-network heterogeneity and on its impact on the swelling, elasticity, and permeability of polymer gels.
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Ebrahimi, Farzad, i Mohammad Reza Barati. "Modeling of smart magnetically affected flexoelectric/piezoelectric nanostructures incorporating surface effects". Nanomaterials and Nanotechnology 7 (1.01.2017): 184798041771310. http://dx.doi.org/10.1177/1847980417713106.
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In this article, electromechanical buckling behavior of size-dependent flexoelectric/piezoelectric nanobeams is investigated based on nonlocal and surface elasticity theories. Flexoelectricity represents the coupling between the strain gradients and electrical polarizations. Flexoelectric/piezoelectric nanostructures can tolerate higher buckling loads compared with conventional piezoelectric ones, especially at lower thicknesses. Nonlocal elasticity theory of Eringen is applied for analyzing flexoelectric/piezoelectric nanobeams for the first time. The flexoelectric/piezoelectric nanobeams are assumed to be in contact with a two-parameter elastic foundation which consists of infinite linear springs and a shear layer. The residual surface stresses which are usually neglected in modeling of flexoelectric nanobeams are incorporated into nonlocal elasticity to provide better understanding of the physics of the problem. Applying an analytical method which satisfies various boundary conditions, the governing equations obtained from Hamilton’s principle are solved. The reliability of the present approach is verified by comparing the obtained results with those provided in literature. Finally, the influences of nonlocal parameter, surface effects plate geometrical parameters, elastic foundation, and boundary conditions on the buckling characteristics of the flexoelectric/piezoelectric nanobeams are explored in detail.
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Khalikov, R. M., O. V. Ivanova, L. N. Korotkova i D. A. Sinitsin. "Supramolecular impactmechanism of polycarboxylate superplasticizers on controlled hardening building nanocomposites". Nanotechnologies in Construction A Scientific Internet-Journal 12, nr 5 (30.10.2020): 250–55. http://dx.doi.org/10.15828/2075-8545-2020-12-5-250-255.
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Introduction. The use of modifying nano-additives in the production of binding building materials is one of the most effective ways to control the technological parameters of concrete by conducting good control of the rheological characteristics reliability. Plasticizing additives increase the water-holding capacity of building compositions, which leads to the dispersed nanosystems stability. This article is focused on examining the physical and chemical mechanisms of the supramolecular effects of polycarboxylate ethers on technological and rheological characteristics of cement nanobinders. Methods and materials. This study describes controlled hardening processes of concrete nanocompositions with demanded technological characteristics in the presence of highly effective plasticizers. Moreover, this paper carries out the analysis of the innovative trends in regulating the consistency of building nanocomposites with the use of new comb-like polycarboxylate esters, which as superplasticizers allow to purposefully influence the kinetics of structure formation of cement nanocomposites. Results. Electrostatic and steric repulsion mechanisms, as well as the dispersing effects of innovative and traditional plasticizing nanoparticles, affect the adsorption and diffusion layers of the hydrated cement nanobinders ultrastructure. The most effective plasticizing properties are shown by comb-like polycarboxylate esters (CPE) with a linear chain molecular weight of ≈12000 g/mol and a length of side branches which correspond to a molecular weight of ≈750 g/mol. The supramolecular mechanism of nanosteric van der Waals repulsive forces begins to be detected at a distance of ≈11 nm, and the elasticity of the lateral branches of innovative CPE is ≈ 5 nm. Individual segments of CPE macromolecules enter the diffuse layer of dispersed nanosystems due to lateral interactions of anions of functional groups, hydrophobic fragments, etc.; they enhance the plasticizing effect of cement binders in concrete nanocompositions. Discussion. When using superplasticizing CPE, the density of concrete nanocomposites can be increased by reducing the amount of water mass to the cement mass ratio to the optimal 0.3; at the same time, technological pumpability and reliability control of the joint hardening kinetics with fillers are preserved within the framework of the technological problems system solutionsconcept. Supramolecular interaction of «anchoring» functional groups of polyacrylic acid containing solid phase cations of cement microparticles, fractal clusters of calcium hydrosilicates and simultaneous steric stabilization of polyethylene glycol radicals give the necessary rheological characteristics to construction nanocompositions and allow the construction of high-strength 55÷80 MPa building materials. Conclusions. The branched comb-like nanostructure of polycarboxylate esters exhibits effective technological characteristics of superplasticizers for concrete, building mortars and dry building mixes