Sara Olesiak | University of Colorado, Boulder (original) (raw)
Papers by Sara Olesiak
Mechanics of Time Dependent Materials, 2010
A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the ... more A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the common trapezoidal testing condition, consisting of constant loading---and unloading---rates with an intervening creep hold period. This full VEP model was applied to analyze nanoindentation test of three polymers and five different types of bone. The full VEP solution allows for direct determination of the viscous term as calculated from the creep hold, while the elastic and plastic material parameters were determined from a non-linear curve-fit of the unloading displacement-time data. Additionally, the use of the trapezoidal loading procedure permitted analysis of the unloading load-displacement data with traditional Oliver-Pharr analysis; the material properties from this analysis compared well with those obtained with VEP analysis. Using the full VEP solution and fitted material constants the loading and creep hold displacement-time curves were simulated and matched well to both polymer and bone experimental data. The full VEP solution shows great promise in for obtaining material parameters for many viscoelastic materials such as hydrated bone, polymers, and other biological tissues.
In Vivo, 2011
Background/Aim: Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MC... more Background/Aim: Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MCSF) are critical to skeletal homeostasis. We investigated the effects of combined IGF-1 plus MCSF on mice. Materials and Methods: C57BL/6J mice, aged 7 weeks, were assigned to baseline, vehicle, IGF-1, MCSF, or combined IGF-1 plus MCSF (1 mg/kg/day each, n=12-13/group, 28-day duration). Results: IGF-1 or MCSF had no effect on bone formation rate; however, IGF-1 plus MCSF produced a 169% increase in periosteal bone formation rate. Combined therapy increased femoral mechanical properties (+25% elastic force), while IGF-1, and MCSF alone did not. Combined therapy affected trabecular bone volume fraction (+40%), number (+13%), and spacing (−13%). MCSF produced similar trabecular changes, while IGF-1 had no effect. Combined therapy and MCSF alone increased bone mineral content. Conclusion: We have demonstrated the superior effects of combined IGF-1 and MCSF. Together, these agents may promote bone modeling to a greater extent than either therapy alone. Lloyd et al: Skeletal Effects of Combined IGF-1 and M-CSF
In vivo (Athens, Greece)
Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MCSF) are critical... more Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MCSF) are critical to skeletal homeostasis. We investigated the effects of combined IGF-1 plus MCSF on mice. C57BL/6J mice, aged 7 weeks, were assigned to baseline, vehicle, IGF-1, MCSF, or combined IGF-1 plus MCSF (1 mg/kg/day each, n=12-13/group, 28-day duration). IGF-1 or MCSF had no effect on bone formation rate; however, IGF-1 plus MCSF produced a 169% increase in periosteal bone formation rate. Combined therapy increased femoral mechanical properties (+25% elastic force), while IGF-1, and MCSF alone did not. Combined therapy affected trabecular bone volume fraction (+40%), number (+13%), and spacing (-13%). MCSF produced similar trabecular changes, while IGF-1 had no effect. Combined therapy and MCSF alone increased bone mineral content. We have demonstrated the superior effects of combined IGF-1 and MCSF. Together, these agents may promote bone modeling to a greater extent than either therapy alone.
Mechanics of Time-Dependent Materials, 2009
A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the ... more A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the common trapezoidal testing condition, consisting of constant loading-and unloading-rates with an intervening creep hold period. This full VEP model was applied to analyze nanoindentation test of three polymers and five different types of bone. The full VEP solution allows for direct determination of the viscous term as calculated from the creep hold, while the elastic and plastic material parameters were determined from a non-linear curve-fit of the unloading displacement-time data. Additionally, the use of the trapezoidal loading procedure permitted analysis of the unloading load-displacement data with traditional Oliver-Pharr analysis; the material properties from this analysis compared well with those obtained with VEP analysis. Using the full VEP solution and fitted material constants the loading and creep hold displacement-time curves were simulated and matched well to both polymer and bone experimental data. The full VEP solution shows great promise in for obtaining material parameters for many viscoelastic materials such as hydrated bone, polymers, and other biological tissues.
With Biological Applications, 2010
ASME 2010 Summer Bioengineering Conference, Parts A and B, 2010
MRS Proceedings, 2008
ABSTRACT A range of mineral content values and organization of the collagen and mineral phases ar... more ABSTRACT A range of mineral content values and organization of the collagen and mineral phases are possible contributors to the significant variance demonstrated within the nanomechanical behavior of mineralized tissues. A combined approach using nanoindentation, to assess nanomechanical behavior, and X-ray diffraction, for analysis of crystallinity and composition, were used to investigate a range of modern and fossilized bone samples. This work provides new insight into the functional role of organization and ...
ASME 2007 Summer Bioengineering Conference, 2007
ABSTRACT
Palaeogeography, Palaeoclimatology, Palaeoecology, 2010
Bone plays a key role in the paleontological and archeological records and can provide insight in... more Bone plays a key role in the paleontological and archeological records and can provide insight into the biology, ecology and the environment of ancient vertebrates. Examination of bone at the tissue level reveals a definitive relationship between nanomechanical properties and the local organic content, mineral content, and microstructural organization. However, it is unclear as to how these properties change following fossilization, or diagenesis, where the organic phase is rapidly removed and the remaining mineral phase is reinforced by the deposition of apatites, calcites, and other minerals. While the process of diagenesis is poorly understood, its outcome clearly results in the potential for dramatic alteration of the mechanical response of biological tissues. In this study, fossilized specimens of mammalian long bones, collected from Colorado and Wyoming, were studied for mechanical variations. Nanoindentation performed in both longitudinal and transverse directions revealed preservation of boneís natural anisotropy as transverse modulus values were consistently smaller than longitudinal values. Additionally, modulus values of fossilized bone from 35.0 to 89.1 GPa increased linearly with logarithm of the sampleís age. Future studies will aim to clarify what mechanical and material elements of bone are retained during diagenesis as bone becomes part of the geologic milieu.
MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS, 2007
Bone plays a key role in the paleontological and archeological records and can provide insight in... more Bone plays a key role in the paleontological and archeological records and can provide insight into the biology, ecology and the environment of ancient vertebrates. Examination of bone at the tissue level reveals a definitive relationship between nanomechanical properties and the local organic content, mineral content, and microstructural organization. However, it is unclear as to how these properties change following fossilization, or diagenesis, where the organic phase is rapidly removed and the ...
Mechanics of Time Dependent Materials, 2010
A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the ... more A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the common trapezoidal testing condition, consisting of constant loading---and unloading---rates with an intervening creep hold period. This full VEP model was applied to analyze nanoindentation test of three polymers and five different types of bone. The full VEP solution allows for direct determination of the viscous term as calculated from the creep hold, while the elastic and plastic material parameters were determined from a non-linear curve-fit of the unloading displacement-time data. Additionally, the use of the trapezoidal loading procedure permitted analysis of the unloading load-displacement data with traditional Oliver-Pharr analysis; the material properties from this analysis compared well with those obtained with VEP analysis. Using the full VEP solution and fitted material constants the loading and creep hold displacement-time curves were simulated and matched well to both polymer and bone experimental data. The full VEP solution shows great promise in for obtaining material parameters for many viscoelastic materials such as hydrated bone, polymers, and other biological tissues.
In Vivo, 2011
Background/Aim: Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MC... more Background/Aim: Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MCSF) are critical to skeletal homeostasis. We investigated the effects of combined IGF-1 plus MCSF on mice. Materials and Methods: C57BL/6J mice, aged 7 weeks, were assigned to baseline, vehicle, IGF-1, MCSF, or combined IGF-1 plus MCSF (1 mg/kg/day each, n=12-13/group, 28-day duration). Results: IGF-1 or MCSF had no effect on bone formation rate; however, IGF-1 plus MCSF produced a 169% increase in periosteal bone formation rate. Combined therapy increased femoral mechanical properties (+25% elastic force), while IGF-1, and MCSF alone did not. Combined therapy affected trabecular bone volume fraction (+40%), number (+13%), and spacing (−13%). MCSF produced similar trabecular changes, while IGF-1 had no effect. Combined therapy and MCSF alone increased bone mineral content. Conclusion: We have demonstrated the superior effects of combined IGF-1 and MCSF. Together, these agents may promote bone modeling to a greater extent than either therapy alone. Lloyd et al: Skeletal Effects of Combined IGF-1 and M-CSF
In vivo (Athens, Greece)
Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MCSF) are critical... more Insulin-like growth factor-1 (IGF-1) and macrophage colony-stimulating factor (MCSF) are critical to skeletal homeostasis. We investigated the effects of combined IGF-1 plus MCSF on mice. C57BL/6J mice, aged 7 weeks, were assigned to baseline, vehicle, IGF-1, MCSF, or combined IGF-1 plus MCSF (1 mg/kg/day each, n=12-13/group, 28-day duration). IGF-1 or MCSF had no effect on bone formation rate; however, IGF-1 plus MCSF produced a 169% increase in periosteal bone formation rate. Combined therapy increased femoral mechanical properties (+25% elastic force), while IGF-1, and MCSF alone did not. Combined therapy affected trabecular bone volume fraction (+40%), number (+13%), and spacing (-13%). MCSF produced similar trabecular changes, while IGF-1 had no effect. Combined therapy and MCSF alone increased bone mineral content. We have demonstrated the superior effects of combined IGF-1 and MCSF. Together, these agents may promote bone modeling to a greater extent than either therapy alone.
Mechanics of Time-Dependent Materials, 2009
A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the ... more A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the common trapezoidal testing condition, consisting of constant loading-and unloading-rates with an intervening creep hold period. This full VEP model was applied to analyze nanoindentation test of three polymers and five different types of bone. The full VEP solution allows for direct determination of the viscous term as calculated from the creep hold, while the elastic and plastic material parameters were determined from a non-linear curve-fit of the unloading displacement-time data. Additionally, the use of the trapezoidal loading procedure permitted analysis of the unloading load-displacement data with traditional Oliver-Pharr analysis; the material properties from this analysis compared well with those obtained with VEP analysis. Using the full VEP solution and fitted material constants the loading and creep hold displacement-time curves were simulated and matched well to both polymer and bone experimental data. The full VEP solution shows great promise in for obtaining material parameters for many viscoelastic materials such as hydrated bone, polymers, and other biological tissues.
With Biological Applications, 2010
ASME 2010 Summer Bioengineering Conference, Parts A and B, 2010
MRS Proceedings, 2008
ABSTRACT A range of mineral content values and organization of the collagen and mineral phases ar... more ABSTRACT A range of mineral content values and organization of the collagen and mineral phases are possible contributors to the significant variance demonstrated within the nanomechanical behavior of mineralized tissues. A combined approach using nanoindentation, to assess nanomechanical behavior, and X-ray diffraction, for analysis of crystallinity and composition, were used to investigate a range of modern and fossilized bone samples. This work provides new insight into the functional role of organization and ...
ASME 2007 Summer Bioengineering Conference, 2007
ABSTRACT
Palaeogeography, Palaeoclimatology, Palaeoecology, 2010
Bone plays a key role in the paleontological and archeological records and can provide insight in... more Bone plays a key role in the paleontological and archeological records and can provide insight into the biology, ecology and the environment of ancient vertebrates. Examination of bone at the tissue level reveals a definitive relationship between nanomechanical properties and the local organic content, mineral content, and microstructural organization. However, it is unclear as to how these properties change following fossilization, or diagenesis, where the organic phase is rapidly removed and the remaining mineral phase is reinforced by the deposition of apatites, calcites, and other minerals. While the process of diagenesis is poorly understood, its outcome clearly results in the potential for dramatic alteration of the mechanical response of biological tissues. In this study, fossilized specimens of mammalian long bones, collected from Colorado and Wyoming, were studied for mechanical variations. Nanoindentation performed in both longitudinal and transverse directions revealed preservation of boneís natural anisotropy as transverse modulus values were consistently smaller than longitudinal values. Additionally, modulus values of fossilized bone from 35.0 to 89.1 GPa increased linearly with logarithm of the sampleís age. Future studies will aim to clarify what mechanical and material elements of bone are retained during diagenesis as bone becomes part of the geologic milieu.
MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS, 2007
Bone plays a key role in the paleontological and archeological records and can provide insight in... more Bone plays a key role in the paleontological and archeological records and can provide insight into the biology, ecology and the environment of ancient vertebrates. Examination of bone at the tissue level reveals a definitive relationship between nanomechanical properties and the local organic content, mineral content, and microstructural organization. However, it is unclear as to how these properties change following fossilization, or diagenesis, where the organic phase is rapidly removed and the ...