The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Joseph M. Mansour - One of the best experts on this subject based on the ideXlab platform.
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scaffold free cartilage subjected to Frictional Shear Stress demonstrates damage by cracking and surface peeling
Journal of Tissue Engineering and Regenerative Medicine, 2017Co-Authors: Adam G Whitney, Karthik Jayaraman, James E. Dennis, Joseph M. MansourAbstract:Scaffold-free engineered cartilage is being explored as a treatment for osteoarthritis. In this study, Frictional Shear Stress was applied to determine the friction and damage behaviour of scaffold-free engineered cartilage, and tissue composition was investigated as it related to damage. Scaffold-free engineered cartilage Frictional Shear Stress was found to exhibit a time-varying response similar to that of native cartilage. However, damage occurred that was not seen in native cartilage, manifesting primarily as tearing through the central plane of the constructs. In engineered cartilage, cells occupied a significantly larger portion of the tissue in the central region where damage was most prominent (18 ± 3% of tissue was comprised of cells in the central region vs 5 ± 1% in the peripheral region; p < 0.0001). In native cartilage, cells comprised 1-4% of tissue for all regions. Average bulk cellularity of engineered cartilage was also greater (68 × 103 ± 4 × 103 vs 52 × 103 ± 22 × 103 cells/mg), although this difference was not significant. Bulk tissue comparisons showed significant differences between engineered and native cartilage in hydroxyproline content (8 ± 2 vs 45 ± 3 µg HYP/mg dry weight), solid content (12.5 ± 0.4% vs 17.9 ± 1.2%), Shear modulus (0.06 ± 0.02 vs 0.15 ± 0.07 MPa) and aggregate modulus (0.12 ± 0.03 vs 0.32 ± 0.14 MPa), respectively. These data indicate that enhanced collagen content and more uniform extracellular matrix distribution are necessary to reduce damage susceptibility. Copyright © 2014 John Wiley & Sons, Ltd.
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Scaffold-free cartilage subjected to Frictional Shear Stress demonstrates damage by cracking and surface peeling.
Journal of tissue engineering and regenerative medicine, 2014Co-Authors: G. Adam Whitney, Karthik Jayaraman, James E. Dennis, Joseph M. MansourAbstract:Scaffold-free engineered cartilage is being explored as a treatment for osteoarthritis. In this study, Frictional Shear Stress was applied to determine the friction and damage behaviour of scaffold-free engineered cartilage, and tissue composition was investigated as it related to damage. Scaffold-free engineered cartilage Frictional Shear Stress was found to exhibit a time-varying response similar to that of native cartilage. However, damage occurred that was not seen in native cartilage, manifesting primarily as tearing through the central plane of the constructs. In engineered cartilage, cells occupied a significantly larger portion of the tissue in the central region where damage was most prominent (18 ± 3% of tissue was comprised of cells in the central region vs 5 ± 1% in the peripheral region; p
Eiichi Yasuda - One of the best experts on this subject based on the ideXlab platform.
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Crack-bridging Processes and Fracture Resistance of a Discontinuous Fiber-reinforced Brittle Matrix Composite
Journal of Materials Research, 1999Co-Authors: Takashi Akatsu, Yasuhiro Tanabe, Eiichi YasudaAbstract:A simple bridging model is proposed for the toughening of a discontinuous fiber-reinforced brittle matrix composite, in which the Frictional bridging of fibers during, as well as after, the interfacial debonding is considered. The R-curve behavior and the work-of-fracture of the composite can be theoretically predicted by the computation of the bridging model applying material parameters, such as fiber volume fraction, size and shape of fibers, fiber tensile strength, elastic moduli of fibers and matrix, fracture toughness and work-of-fracture of matrix, and Frictional Shear Stress at interface. The experimental result obtained from a SiC-whisker-reinforced Al2O3 composite confirms the theoretical predictions of the present bridging model. Through the model calculation, the R-curve, crack profile, and bridging Stresses of the composite can be estimated correspondingly to the bridging processes.
James E. Dennis - One of the best experts on this subject based on the ideXlab platform.
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scaffold free cartilage subjected to Frictional Shear Stress demonstrates damage by cracking and surface peeling
Journal of Tissue Engineering and Regenerative Medicine, 2017Co-Authors: Adam G Whitney, Karthik Jayaraman, James E. Dennis, Joseph M. MansourAbstract:Scaffold-free engineered cartilage is being explored as a treatment for osteoarthritis. In this study, Frictional Shear Stress was applied to determine the friction and damage behaviour of scaffold-free engineered cartilage, and tissue composition was investigated as it related to damage. Scaffold-free engineered cartilage Frictional Shear Stress was found to exhibit a time-varying response similar to that of native cartilage. However, damage occurred that was not seen in native cartilage, manifesting primarily as tearing through the central plane of the constructs. In engineered cartilage, cells occupied a significantly larger portion of the tissue in the central region where damage was most prominent (18 ± 3% of tissue was comprised of cells in the central region vs 5 ± 1% in the peripheral region; p < 0.0001). In native cartilage, cells comprised 1-4% of tissue for all regions. Average bulk cellularity of engineered cartilage was also greater (68 × 103 ± 4 × 103 vs 52 × 103 ± 22 × 103 cells/mg), although this difference was not significant. Bulk tissue comparisons showed significant differences between engineered and native cartilage in hydroxyproline content (8 ± 2 vs 45 ± 3 µg HYP/mg dry weight), solid content (12.5 ± 0.4% vs 17.9 ± 1.2%), Shear modulus (0.06 ± 0.02 vs 0.15 ± 0.07 MPa) and aggregate modulus (0.12 ± 0.03 vs 0.32 ± 0.14 MPa), respectively. These data indicate that enhanced collagen content and more uniform extracellular matrix distribution are necessary to reduce damage susceptibility. Copyright © 2014 John Wiley & Sons, Ltd.
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Scaffold-free cartilage subjected to Frictional Shear Stress demonstrates damage by cracking and surface peeling.
Journal of tissue engineering and regenerative medicine, 2014Co-Authors: G. Adam Whitney, Karthik Jayaraman, James E. Dennis, Joseph M. MansourAbstract:Scaffold-free engineered cartilage is being explored as a treatment for osteoarthritis. In this study, Frictional Shear Stress was applied to determine the friction and damage behaviour of scaffold-free engineered cartilage, and tissue composition was investigated as it related to damage. Scaffold-free engineered cartilage Frictional Shear Stress was found to exhibit a time-varying response similar to that of native cartilage. However, damage occurred that was not seen in native cartilage, manifesting primarily as tearing through the central plane of the constructs. In engineered cartilage, cells occupied a significantly larger portion of the tissue in the central region where damage was most prominent (18 ± 3% of tissue was comprised of cells in the central region vs 5 ± 1% in the peripheral region; p
Karthik Jayaraman - One of the best experts on this subject based on the ideXlab platform.
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scaffold free cartilage subjected to Frictional Shear Stress demonstrates damage by cracking and surface peeling
Journal of Tissue Engineering and Regenerative Medicine, 2017Co-Authors: Adam G Whitney, Karthik Jayaraman, James E. Dennis, Joseph M. MansourAbstract:Scaffold-free engineered cartilage is being explored as a treatment for osteoarthritis. In this study, Frictional Shear Stress was applied to determine the friction and damage behaviour of scaffold-free engineered cartilage, and tissue composition was investigated as it related to damage. Scaffold-free engineered cartilage Frictional Shear Stress was found to exhibit a time-varying response similar to that of native cartilage. However, damage occurred that was not seen in native cartilage, manifesting primarily as tearing through the central plane of the constructs. In engineered cartilage, cells occupied a significantly larger portion of the tissue in the central region where damage was most prominent (18 ± 3% of tissue was comprised of cells in the central region vs 5 ± 1% in the peripheral region; p < 0.0001). In native cartilage, cells comprised 1-4% of tissue for all regions. Average bulk cellularity of engineered cartilage was also greater (68 × 103 ± 4 × 103 vs 52 × 103 ± 22 × 103 cells/mg), although this difference was not significant. Bulk tissue comparisons showed significant differences between engineered and native cartilage in hydroxyproline content (8 ± 2 vs 45 ± 3 µg HYP/mg dry weight), solid content (12.5 ± 0.4% vs 17.9 ± 1.2%), Shear modulus (0.06 ± 0.02 vs 0.15 ± 0.07 MPa) and aggregate modulus (0.12 ± 0.03 vs 0.32 ± 0.14 MPa), respectively. These data indicate that enhanced collagen content and more uniform extracellular matrix distribution are necessary to reduce damage susceptibility. Copyright © 2014 John Wiley & Sons, Ltd.
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Scaffold-free cartilage subjected to Frictional Shear Stress demonstrates damage by cracking and surface peeling.
Journal of tissue engineering and regenerative medicine, 2014Co-Authors: G. Adam Whitney, Karthik Jayaraman, James E. Dennis, Joseph M. MansourAbstract:Scaffold-free engineered cartilage is being explored as a treatment for osteoarthritis. In this study, Frictional Shear Stress was applied to determine the friction and damage behaviour of scaffold-free engineered cartilage, and tissue composition was investigated as it related to damage. Scaffold-free engineered cartilage Frictional Shear Stress was found to exhibit a time-varying response similar to that of native cartilage. However, damage occurred that was not seen in native cartilage, manifesting primarily as tearing through the central plane of the constructs. In engineered cartilage, cells occupied a significantly larger portion of the tissue in the central region where damage was most prominent (18 ± 3% of tissue was comprised of cells in the central region vs 5 ± 1% in the peripheral region; p
Stanislav N. Gorb - One of the best experts on this subject based on the ideXlab platform.
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Surface topography and contact mechanics of dry and wet human skin.
Beilstein Journal of Nanotechnology, 2014Co-Authors: Alexander Kovalev, Kirstin Dening, B N J Persson, Stanislav N. GorbAbstract:The surface topography of the human wrist skin is studied by using optical and atomic force microscopy (AFM) methods. By using these techniques the surface roughness power spectrum is obtained. The Persson contact mechanics theory is used to calculate the contact area for different magnifications, for the dry and wet skin. The measured friction coefficient between a glass ball and dry and wet skin can be explained assuming that a Frictional Shear Stress σf ≈ 13 MPa and σf ≈ 5 MPa, respectively, act in the area of real contact during sliding. These Frictional Shear Stresses are typical for sliding on surfaces of elastic bodies. The big increase in friction, which has been observed for glass sliding on wet skin as the skin dries up, can be explained as result of the increase in the contact area arising from the attraction of capillary bridges. Finally, we demonstrated that the real contact area can be properly defined only when a combination of both AFM and optical methods is used for power spectrum calculation.
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contact mechanics and friction on dry and wet human skin
Tribology Letters, 2013Co-Authors: B N J Persson, Alexander Kovalev, Stanislav N. GorbAbstract:The surface topography of the human wrist skin is studied using an optical method and the surface roughness power spectrum is obtained. The Persson contact mechanics theory is used to calculate the contact area for different magnifications, for both dry and wet condition of the skin. For dry skin, plastic yielding becomes important and will determine the area of contact observed at the highest magnification. The measured friction coefficient [M.J. Adams et al., Tribol Lett 26:239, 2007] on both dry and wet skin can be explained assuming that a Frictional Shear Stress σf ≈ 15 MPa acts in the area of real contact during sliding. This Frictional Shear Stress is typical for sliding on polymer surfaces, and for thin (nanometer) confined fluid films. The big increase in the friction, which has been observed for glass sliding on wet skin as the skin dries up, can be explained as resulting from the increase in the contact area arising from the attraction of capillary bridges. This effect is predicted to operate as long as the water layer is thinner than ∼14 μm, which is in good agreement with the time period (of order 100 s) over which the enhanced friction is observed (it takes about 100 s for ∼14 μm water to evaporate at 50% relative humidity and at room temperature). We calculate the dependency of the sliding friction coefficient on the sliding speed on lubricated surfaces (Stribeck curve). We show that sliding of a sphere and of a cylinder gives very similar results if the radius and load on the sphere and cylinder are appropriately related. When applied to skin the calculated Stribeck curve is in good agreement with experiment, except that the curve is shifted by one velocity-decade to higher velocities than observed experimentally. We explain this by the role of the skin and underlying tissues viscoelasticity on the contact mechanics.
