The Experts below are selected from a list of 17124 Experts worldwide ranked by ideXlab platform
Tony M. Keaveny - One of the best experts on this subject based on the ideXlab platform.
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Nonlinear Behavior of Trabecular Bone at Small Strains
Journal of biomechanical engineering, 2000Co-Authors: Elise F. Morgan, Oscar C. Yeh, Wesley C. Chang, Tony M. KeavenyAbstract:Study of the behavior of trabecular bone at Strains below 0.40 Percent is of clinical and biomechanical importance. The goal of this work was to characterize, with respect to anatomic site, loading mode, and apparent density, the subtle concave downward stress-Strain nonlinearity, that has been observed recently for trabecular bone at these Strains. Using protocols designed to minimize end-artifacts, 155 cylindrical cores from human vertebrae, proximal tibiae, proximal femora, and bovine proximal tibiae were mechanically tested to yield at 0.50 Percent Strain per second in tension or compression. The nonlinearity was quantified by the reduction in tangent modulus at 0.20 Percent and 0.40 Percent Strain as compared to the initial modulus. For the pooled data, the mean +/- SD Percentage reduction in tangent modulus at 0.20 Percent Strain was 9.07+/- 3.24 Percent in compression and 13.8 +/- 4.79 Percent in tension. At 0.40 Percent Strain, these values were 23.5 +/- 5.71 and 35.7+/- 7.10 Percent, respectively. The magnitude of the nonlineari't depended on both anatomic site (p < 0.001) and loading mode (p < 0.001), and in tension was positively correlated with density. Calculated values of elastic modulus and yield properties depended on the Strain range chosen to define modulus via a linear curve fit (p < 0.005). Mean Percent differences in 0.20 Percent offset yield Strains were as large as 10.65 Percent for some human sites. These results establish that trabecular bone exhibits nonlinearity at low Strains, and that this behavior can confound intersite comparisons of mechanical properties. A nonlinear characterization of the small Strain behavior of trabecular bone was introduced to characterize the initial stress-Strain behavior more thoroughly.
Elise F. Morgan - One of the best experts on this subject based on the ideXlab platform.
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Nonlinear Behavior of Trabecular Bone at Small Strains
Journal of biomechanical engineering, 2000Co-Authors: Elise F. Morgan, Oscar C. Yeh, Wesley C. Chang, Tony M. KeavenyAbstract:Study of the behavior of trabecular bone at Strains below 0.40 Percent is of clinical and biomechanical importance. The goal of this work was to characterize, with respect to anatomic site, loading mode, and apparent density, the subtle concave downward stress-Strain nonlinearity, that has been observed recently for trabecular bone at these Strains. Using protocols designed to minimize end-artifacts, 155 cylindrical cores from human vertebrae, proximal tibiae, proximal femora, and bovine proximal tibiae were mechanically tested to yield at 0.50 Percent Strain per second in tension or compression. The nonlinearity was quantified by the reduction in tangent modulus at 0.20 Percent and 0.40 Percent Strain as compared to the initial modulus. For the pooled data, the mean +/- SD Percentage reduction in tangent modulus at 0.20 Percent Strain was 9.07+/- 3.24 Percent in compression and 13.8 +/- 4.79 Percent in tension. At 0.40 Percent Strain, these values were 23.5 +/- 5.71 and 35.7+/- 7.10 Percent, respectively. The magnitude of the nonlineari't depended on both anatomic site (p < 0.001) and loading mode (p < 0.001), and in tension was positively correlated with density. Calculated values of elastic modulus and yield properties depended on the Strain range chosen to define modulus via a linear curve fit (p < 0.005). Mean Percent differences in 0.20 Percent offset yield Strains were as large as 10.65 Percent for some human sites. These results establish that trabecular bone exhibits nonlinearity at low Strains, and that this behavior can confound intersite comparisons of mechanical properties. A nonlinear characterization of the small Strain behavior of trabecular bone was introduced to characterize the initial stress-Strain behavior more thoroughly.
Andrew A. Peterson - One of the best experts on this subject based on the ideXlab platform.
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High Elastic Strain Directly Tunes the Hydrogen Evolution Reaction on Tungsten Carbide
Journal of Physical Chemistry C, 2017Co-Authors: Alireza Khorshidi, Pradeep R Guduru, Andrew A. PetersonAbstract:Elastic Strain provides a direct means to tune a material’s electronic structure from both computational and experimental vantage points and can thus provide insights into surface reactivity via changes induced by electronic structure shifts. Here we investigate the role of elastic Strain on the catalytic activity of tungsten carbide (WC) in the hydrogen evolution reaction. WC makes an interesting material for such investigations as it is an inherently promising catalyst that can sustain larger elastic Strains (e.g., −1.4 to 1.4%) than common transition-metal catalysts, such as Pt or Ni (e.g., −0.4 to 0.4%). On the basis of density functional theory calculations, a compressive uniaxial Strain is expected to cause weakening of the surface–hydrogen interaction of 10–15 meV per Percent Strain, while a tensile Strain is calculated to strengthen the surface–hydrogen interaction by a similar magnitude. Sabatier analysis suggests that weakening of the surface-hydrogen interaction would enhance catalysis. We prep...
François Léonard - One of the best experts on this subject based on the ideXlab platform.
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Many-body effects on the electronic and optical properties of Strained semiconducting carbon nanotubes
Physical Review B, 2013Co-Authors: Catalin D. Spataru, François LéonardAbstract:We present many-body \textit{ab initio} calculations of the electronic and optical properties of semiconducting zigzag carbon nanotubes under uniaxial Strain. The GW approach is utilized to obtain the quasiparticle bandgaps and is combined with the Bethe-Salpeter equation to obtain the optical absorption spectrum. We find that the dependence of the electronic bandgaps on Strain is more complex than previously predicted based on tight-binding models or density-functional theory. In addition, we show that the exciton energy and exciton binding energy depend significantly on Strain, with variations of tens of meVs per Percent Strain, but that despite these strong changes the absorbance is found to be nearly independent of Strain. Our results provide new guidance for the understanding and design of optomechanical systems based on carbon nanotubes.
Lorna J. Gibson - One of the best experts on this subject based on the ideXlab platform.
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Microdamage accumulation in bovine trabecular bone in uniaxial compression.
Journal of biomechanical engineering, 2001Co-Authors: T. L. Arthur Moore, Lorna J. GibsonAbstract:In this study we investigated how microdamage accumulated with increasing compressive Strain in bovine trabecular bone. We found that little damage is created in the linear elastic region, up to -0.4 Percent Strain. At an average Strain of -0.76 Percent +/-0.25 Percent, the stress-Strain curve became nonlinear, and peaked at -1.91 Percent +/-0.55 Percent Strain. Microdamage increases rapidly during the peak of the stress-Strain curve, and a localized band of damage formed. At Strains beyond the ultimate Strain, the damaged band widened and the density of damage within the band increased. Microdamage occurred as groupings of cracks; the majority of damage occurred as regions of cross-hatching. All microdamage parameters increased with increasing maximum compressive Strain. We also observed exponential relationships between crack numerical density and damage (1(o) - (o)Esec/E0) and between crack length density and damage.