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Eric A. Nauman - One of the best experts on this subject based on the ideXlab platform.
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds.
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metal™) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 × 10−10 to 4.8 × 10−10 m2 and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure–function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metaltrade mark) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 x 10(-10) to 4.8 x 10(-10) m(2) and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure-function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material.
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds
Journal of Biomedical Materials Research, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metal) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 x 10 - 1 0 to 4.8 x 10 - 1 0 m 2 and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure-function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material.
Daniel A. Shimko - One of the best experts on this subject based on the ideXlab platform.
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds.
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metal™) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 × 10−10 to 4.8 × 10−10 m2 and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure–function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metaltrade mark) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 x 10(-10) to 4.8 x 10(-10) m(2) and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure-function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material.
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds
Journal of Biomedical Materials Research, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metal) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 x 10 - 1 0 to 4.8 x 10 - 1 0 m 2 and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure-function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material.
David H Cohen - One of the best experts on this subject based on the ideXlab platform.
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the Effect of Porosity on x ray emission line profiles from hot star winds
The Astrophysical Journal, 2006Co-Authors: S P Owocki, David H CohenAbstract:We investigate the degree to which the nearly symmetric form of X-ray emission lines seen in Chandra spectra of early-type supergiant stars could be explained by the possibly porous nature of their spatially structured stellar winds. Such Porosity could Effectively reduce the bound-free absorption of X-rays emitted by embedded wind shocks, and thus allow a more similar transmission of redshifted and blueshifted emission from the back and front hemispheres, respectively. To obtain the localized self-shielding that is central to this Porosity Effect, it is necessary that the individual clumps be optically thick. In a medium consisting of clumps of size l and volume filling factor f, we argue that the general modification in Effective opacity should scale approximately as κeff ≈ κ/ , where, for a given atomic opacity κ and mean density ρ, the clump optical thickness scales as τc = κρl/f. For a simple wind structure parameterization in which the "Porosity length" h ≡ l/f increases with local radius r as h = h'r, we find that a substantial reduction in wind absorption requires a quite large Porosity scale factor, h' 1, implying large Porosity lengths h r. The associated wind structure must thus have either a relatively large scale l r, or a small volume filling factor f ≈ l/r 1, or some combination of these. We argue that the relatively small-scale, moderate compressions generated by intrinsic instabilities in line driving are unlikely to give such large Porosity lengths. This raises questions about whether Porosity Effects could play a significant role in explaining nearly symmetric X-ray line profiles, leaving the prospect of instead having to invoke a substantial (approximately a factor of 5) downward revision in the assumed mass-loss rates.
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the Effect of Porosity on x ray emission line profiles from hot star winds
arXiv: Astrophysics, 2006Co-Authors: S P Owocki, David H CohenAbstract:We investigate the degree to which the nearly symmetric form of X-ray emission lines seen in Chandra spectra of early-type supergiant stars could be explained by a possibly porous nature of their spatially structured stellar winds. Such Porosity could Effectively reduce the bound-free absorption of X-rays emitted by embedded wind shocks, and thus allow a more similar transmission of red- vs. blue-shifted emission from the back vs. front hemispheres. For a medium consisting of clumps of size l and volume filling factor f, in which the `Porosity length' h=l/f increases with local radius as h = h' r, we find that a substantial reduction in wind absorption requires a quite large Porosity scale factor h' > 1, implying large Porosity lengths h > r. The associated wind structure must thus have either a relatively large scale l~ r, or a small volume filling factor f ~ l/r << 1, or some combination of these. The relatively small-scale, moderate compressions generated by intrinsic instabilities in line-driving seem unlikely to give such large Porosity lengths, leaving again the prospect of instead having to invoke a substantial (ca. factor 5) downward revision in assumed mass-loss rates.
Patrick Dangla - One of the best experts on this subject based on the ideXlab platform.
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Effect of Porosity on thermal expansion coefficient of cement pastes and mortars
Construction and Building Materials, 2012Co-Authors: Qiang Zeng, Teddy Fen-chong, Patrick DanglaAbstract:The thermal expansion coefficient (TEC) is studied for air-entrained cement pastes and mortars with different Porosity. The results show that the Porosity has significant Effect on the thermal deformation and TEC decreases with Porosity. The relation between TEC and Porosity observes a power law, αd = α0(1 − ϕ)C, and the exponents C for pastes/mortars are respectively 2.66/2.38 in terms of total Porosity, and 3.74/2.69 in terms of air void content. The gravimetry and MIP measurements on the Porosity and pore size distribution (PSD) indicate that the entrained air voids have not significant influence on the capillary Porosity, but change the PSD curves measured by MIP. Three characteristic pore ranges are identified on these PSD curves and air voids are found to interfere with the mercury intrusion process above the scale of 50 nm. Thermal gravity analysis shows that the composition of hydration products and cement hydration degree for both pastes and mortars are almost the same. The decreased TEC with air-entrainment can probably be attributed to the existence of dense shell structures around the air voids.
Edward A. Sander - One of the best experts on this subject based on the ideXlab platform.
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds.
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metal™) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 × 10−10 to 4.8 × 10−10 m2 and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure–function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metaltrade mark) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 x 10(-10) to 4.8 x 10(-10) m(2) and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure-function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material.
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Effect of Porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds
Journal of Biomedical Materials Research, 2005Co-Authors: Daniel A. Shimko, Valerie Franz Shimko, Edward A. Sander, Kyle F. Dickson, Eric A. NaumanAbstract:In many cases of traumatic bone injury, bone grafting is required. The primary source of graft material is either autograft or allograft. The use of both material sources are well established, however, both suffer limitations. In response, many grafting alternatives are being explored. This article specifically focuses on a porous tantalum metal grafting material (Trabecular Metal) marketed by Zimmer. Twenty-one cylindrical scaffolds were manufactured (66% to 88% porous) and tested for Porosity, intrinsic permeability, tangent elastic modulus, and for yield stress and strain behavior. Scaffold microstructural geometries were also measured. Tantalum scaffold intrinsic permeability ranged from 2.1 x 10 - 1 0 to 4.8 x 10 - 1 0 m 2 and tangent elastic modulus ranged from 373 MPa to 2.2 GPa. Both intrinsic permeability and tangent elastic modulus closely matched Porosity-matched cancellous bone specimens from a variety of species and anatomic locations. Scaffold yield stress ranged from 4 to 12.7 MPa and was comparable to bovine and human cancellous bone. Yield strain was unaffected by scaffold Porosity (average = 0.010 mm/mm). Understanding these structure-function relationships will help complete the basic physical characterization of this new material and will aid in the development of realistic mathematical models, ultimately enhancing future implant designs utilizing this material.