The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
E P George - One of the best experts on this subject based on the ideXlab platform.
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thermal expansion behavior of a Directionally solidified nial mo composite investigated by neutron diffraction and dilatometry
Journal of Applied Physics, 2005Co-Authors: E P George, G M Pha, Hah Choo, Wallace D Porte, M A M OurkeAbstract:The thermal expansion of Directionally solidified NiAl–Mo eutectic alloys consisting of nanoscale Mo Fibers embedded in a NiAl matrix was analyzed by neutron diffraction and dilatometry. From room temperature to 800°C, perpendicular to the Fiber Direction, the NiAl and Mo phases expand independently with average coefficients of thermal expansion (CTEs) of 16.0×10−6°C−1 and 5.8×10−6°C−1, respectively. Parallel to the Fiber Direction, they coexpand up to 650°C with an average CTE of 12.8×10−6°C−1, but above this temperature the Mo Fibers expand more than the NiAl matrix. This anomalous behavior is the result of the load transfer to the Mo Fibers when the NiAl matrix softens. The average CTE of the composite parallel to the Fiber Direction was determined by dilatometry to be 13.0×10−6°C−1, which is approximately 11% lower than the value predicted by a simple rule of mixtures using the CTEs of the constituent phases.
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Thermal-expansion behavior of a Directionally solidified NiAl–Mo composite investigated by neutron diffraction and dilatometry
Journal of Applied Physics, 2005Co-Authors: Hongbin Bei, E P George, Donald W. Brown, George M. Pharr, Hahn Choo, W. D. Porter, Mark A.m. BourkeAbstract:The thermal expansion of Directionally solidified NiAl–Mo eutectic alloys consisting of nanoscale Mo Fibers embedded in a NiAl matrix was analyzed by neutron diffraction and dilatometry. From room temperature to 800°C, perpendicular to the Fiber Direction, the NiAl and Mo phases expand independently with average coefficients of thermal expansion (CTEs) of 16.0×10−6°C−1 and 5.8×10−6°C−1, respectively. Parallel to the Fiber Direction, they coexpand up to 650°C with an average CTE of 12.8×10−6°C−1, but above this temperature the Mo Fibers expand more than the NiAl matrix. This anomalous behavior is the result of the load transfer to the Mo Fibers when the NiAl matrix softens. The average CTE of the composite parallel to the Fiber Direction was determined by dilatometry to be 13.0×10−6°C−1, which is approximately 11% lower than the value predicted by a simple rule of mixtures using the CTEs of the constituent phases.
Mark A.m. Bourke - One of the best experts on this subject based on the ideXlab platform.
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Thermal-expansion behavior of a Directionally solidified NiAl–Mo composite investigated by neutron diffraction and dilatometry
Journal of Applied Physics, 2005Co-Authors: Hongbin Bei, E P George, Donald W. Brown, George M. Pharr, Hahn Choo, W. D. Porter, Mark A.m. BourkeAbstract:The thermal expansion of Directionally solidified NiAl–Mo eutectic alloys consisting of nanoscale Mo Fibers embedded in a NiAl matrix was analyzed by neutron diffraction and dilatometry. From room temperature to 800°C, perpendicular to the Fiber Direction, the NiAl and Mo phases expand independently with average coefficients of thermal expansion (CTEs) of 16.0×10−6°C−1 and 5.8×10−6°C−1, respectively. Parallel to the Fiber Direction, they coexpand up to 650°C with an average CTE of 12.8×10−6°C−1, but above this temperature the Mo Fibers expand more than the NiAl matrix. This anomalous behavior is the result of the load transfer to the Mo Fibers when the NiAl matrix softens. The average CTE of the composite parallel to the Fiber Direction was determined by dilatometry to be 13.0×10−6°C−1, which is approximately 11% lower than the value predicted by a simple rule of mixtures using the CTEs of the constituent phases.
M A M Ourke - One of the best experts on this subject based on the ideXlab platform.
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thermal expansion behavior of a Directionally solidified nial mo composite investigated by neutron diffraction and dilatometry
Journal of Applied Physics, 2005Co-Authors: E P George, G M Pha, Hah Choo, Wallace D Porte, M A M OurkeAbstract:The thermal expansion of Directionally solidified NiAl–Mo eutectic alloys consisting of nanoscale Mo Fibers embedded in a NiAl matrix was analyzed by neutron diffraction and dilatometry. From room temperature to 800°C, perpendicular to the Fiber Direction, the NiAl and Mo phases expand independently with average coefficients of thermal expansion (CTEs) of 16.0×10−6°C−1 and 5.8×10−6°C−1, respectively. Parallel to the Fiber Direction, they coexpand up to 650°C with an average CTE of 12.8×10−6°C−1, but above this temperature the Mo Fibers expand more than the NiAl matrix. This anomalous behavior is the result of the load transfer to the Mo Fibers when the NiAl matrix softens. The average CTE of the composite parallel to the Fiber Direction was determined by dilatometry to be 13.0×10−6°C−1, which is approximately 11% lower than the value predicted by a simple rule of mixtures using the CTEs of the constituent phases.
Can A. Yucesoy - One of the best experts on this subject based on the ideXlab platform.
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Principles of the Mechanism for Epimuscular Myofascial Loads Leading to Non-uniform Strain Distributions Along Muscle Fiber Direction: Finite Element Modeling.
Frontiers in physiology, 2020Co-Authors: Uluç Pamuk, Alican Onur Cankaya, Can A. YucesoyAbstract:Sarcomere lengths and their changes are key determinants of muscle active force production. Recent studies indicate inhomogeneity of sarcomere lengths within the muscle. Studies utilizing magnetic resonance imaging (MRI) analyses for quantifying local muscle tissue strains and diffusion tensor imaging (DTI) analyses allowing for determination of their components along muscle fascicles show that those length changes can be non-uniform. Specifically, two questions arise regarding the muscle's length change heterogeneities along the muscle Fiber Direction: (1) How can a passively lengthened muscle show shortened regions? (2) How can an isometric contracting muscle show lengthened parts? Using finite element modeling and studying principles of the mechanism of strain heterogeneity along the muscle Fiber Direction, the aim was to test the following hypothesis: epimuscular myofascial loads can lead locally to strains opposing those elsewhere within the muscle that are determined by the globally imposed conditions. The geometry of the model was defined by the contour of a longitudinal slice of the rat extensor digitorum longus (EDL) muscle belly. Three models were studied: (1) isolated muscle (muscle modeled fully isolated from its surroundings) and models aiming at representing the principles of a muscle in its in vivo context including (2) extramuscularly connected muscle (muscle's connections to non-muscular structures are modeled exclusively) and (3) epimuscularly connected muscle (additionally muscle's connections to neighboring muscle are modeled). Three cases were studied: passive isometric muscle with imposed relative position change (Case I), passive lengthened muscle (Case II), and active isometric muscle with imposed relative position change (Case III). The findings indicated non-uniform strains for all models except for zero strain in model (1) in Case I, but models (2) and (3) also showed strains opposing the imposed effect. Case I: model (3) showed shortened and lengthened sections (up to 35.3%), caused exclusively by imposed relative position change. Case II: models (2) and (3) showed shortened sections (up to 12.7 and 19.5%, respectively) in addition to lengthened sections. Case III: models (2) and (3) showed lengthened sections (up to 5 and 23.4%, respectively) in addition to shortened sections. These effects get more pronounced with stiffer epimuscular connections. Assessments of forces exerted on the muscle by the epimuscular connections showed that such strain heterogeneities are ascribed to epimuscular myofascial loads determined by muscle relative position changes.
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combined magnetic resonance and diffusion tensor imaging analyses provide a powerful tool for in vivo assessment of deformation along human muscle Fibers
Journal of The Mechanical Behavior of Biomedical Materials, 2016Co-Authors: Uluç Pamuk, Cengizhan Ozturk, Agah Karakuzu, Burak Acar, Can A. YucesoyAbstract:Muscle Fiber Direction strain provides invaluable information for characterizing muscle function. However, methods to study this for human muscles in vivo are lacking. Using magnetic resonance (MR) imaging based deformation analyses and diffusion tensor (DT) imaging based tractography combined, we aimed to assess muscle Fiber Direction local tissue deformations within the human medial gastrocnemius (GM) muscle. Healthy female subjects (n=5, age=27±1 years) were positioned prone within the MR scanner in a relaxed state with the ankle angle fixed at 90°. The knee was brought to flexion (140.8±3.0°) (undeformed state). Sets of 3D high resolution MR, and DT images were acquired. This protocol was repeated at extended knee joint position (177.0±1.0°) (deformed state). Tractography and Demons nonrigid registration algorithm was utilized to calculate local deformations along muscle fascicles. Undeformed state images were also transformed by a synthetic rigid body motion to calculate strain errors. Mean strain errors were significantly smaller then mean Fiber Direction strains (lengthening: 0.2±0.1% vs. 8.7±8.5%; shortening: 3.3±0.9% vs. 7.5±4.6%). Shortening and lengthening (up to 23.3% and 116.7%, respectively) occurs simultaneously along individual fascicles despite imposed GM lengthening. Along-Fiber shear strains confirm the presence of much shearing between fascicles. Mean Fiber Direction strains of different tracts also show non-uniform distribution. Inhomogeneity of Fiber strain indicates epimuscular myofascial force transmission. We conclude that MR and DT imaging analyses combined provide a powerful tool for quantifying deformation along human muscle Fibers in vivo. This can help substantially achieving a better understanding of normal and pathological muscle function and mechanisms of treatment techniques.
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Assessment of in-vivo skeletal muscle mechanics during joint motion using multimodal magnetic resonance imaging based approaches
2014 18th National Biomedical Engineering Meeting, 2014Co-Authors: Agah Karakuzu, Cengizhan Ozturk, Uluç Pamuk, Can A. YucesoyAbstract:The aim of this study is to quantify local deformations in the Direction of muscle Fibers occurred during joint motion by using specific Magnetic Resonance Imaging (MRI) sequences and post-processing tecniques.Data acquisition was performed within the body of preliminary study with the participaton of a 23 years old healthy male subject. Diffusion Tensor (DT) and Phase Contrast (PC) image sets are acquired during the cyclic ankle movement within the 80°-110° ankle angle range (10° dorsiflexion and 20° plantarflexion) and at the frequency of 0.5 Hz. Post processing techniques were used to quantify Fiber Direction strain distribution for both of the m. Gastrocnemius and m. Soleus. Fiber Direction peak lengthening and shortening values for the m. Gastrocnemius were calculated as 7.1% and 30.8%, respectively. However a significant lengthening was not observed for m. Soleus, Fiber Direction peak shortening value was calculated as 24.6% for the same muscle. In consideration of this findings, it is noticed that the Fiber Direction strain distribution is significantly heterogeneous.Moreover, coexistence of the local lengthenings and local shortenings within the Fiber Direction strain distribution is found to be remarkable. From the clinical perspective,these quantified parameters have a significance to understand movement limitations caused by spasticity and contractures which may occur concominantly.
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Demonstration of Fiber Direction glycogen in the rat EDL muscle with longitudinal sections: Histological assessment
2010 15th National Biomedical Engineering Meeting, 2010Co-Authors: Zeynep F. Susam, Filiz Ateş, Can A. YucesoyAbstract:In this study, the distribution of glycogen in Fiber Direction is examined histologically in rat EDL muscle in order to investigate the intramuscular mechanism of botox. The muscle was not exposed to any physical activity or electrical stimulation; it was directly subjected to histological study. The longitudinal sections obtained from the paraffin-embedded tissue was stained by Periodic Acid and Schiff (PAS) solutions, afterwards hematoxylin Mayer's and bluing agent was added. Under the influence of PAS, the areas containing glycogen was observed as blue and the nuclei was dark blue. Furthermore, Fiber Directions were also determined with the contribution of the second step. As a result of these studies it was observed that glycogen was distributed among the whole muscle in the Fiber Direction. Utilizing the obtained findings, botox injected muscle will be stained with PAS and paralyzed muscle Fiber patterns will be determined. The mechanical effects of botox will be examined intramuscularly and the first results will be presented in the congress.
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Magnetic resonance imaging shows that muscle myofascial force transmission causes substantial sarcomere length heterogeneity in human muscles, in vivo
2010 15th National Biomedical Engineering Meeting, 2010Co-Authors: Alper Yaman, Guus C. Baan, Peter A. Huijing, Cengizhan Ozturk, Can A. YucesoyAbstract:In this study, it is aimed to show, using magnetic resonance imaging (MRI), effects of epimuscular myofascial force transmission (EMFT) on sarcomere length distribution in human muscles in lower leg in vivo. The ankle angle of the subjects was fixed and 3D MR image sets were acquired for two different knee angles. Intensity based non-rigid demon algorithm was used to calculate displacement fields and Green-Lagrange strain for each voxel. To calculate the strain in local Fiber Direction diffusion tensor images (DTI) were acquired. It was showed that m. gastrocnemius crossing the knee has major strain distribution (0.125 ± 0.010 in proximal and 0.073 ± 0.014 distal) in local Fiber Direction. Despite remaining isometric during the experiment, synergistic m. soleus (e.g. 0.088 ± 0.017 in proximal, 0.078 ± 0.019 in distal) and even antagonistic muscles (0.157 ± 0.070, 0.108 ± 0.037) also show major strain distribution in the local Fiber Direction.
Hongbin Bei - One of the best experts on this subject based on the ideXlab platform.
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Thermal-expansion behavior of a Directionally solidified NiAl–Mo composite investigated by neutron diffraction and dilatometry
Journal of Applied Physics, 2005Co-Authors: Hongbin Bei, E P George, Donald W. Brown, George M. Pharr, Hahn Choo, W. D. Porter, Mark A.m. BourkeAbstract:The thermal expansion of Directionally solidified NiAl–Mo eutectic alloys consisting of nanoscale Mo Fibers embedded in a NiAl matrix was analyzed by neutron diffraction and dilatometry. From room temperature to 800°C, perpendicular to the Fiber Direction, the NiAl and Mo phases expand independently with average coefficients of thermal expansion (CTEs) of 16.0×10−6°C−1 and 5.8×10−6°C−1, respectively. Parallel to the Fiber Direction, they coexpand up to 650°C with an average CTE of 12.8×10−6°C−1, but above this temperature the Mo Fibers expand more than the NiAl matrix. This anomalous behavior is the result of the load transfer to the Mo Fibers when the NiAl matrix softens. The average CTE of the composite parallel to the Fiber Direction was determined by dilatometry to be 13.0×10−6°C−1, which is approximately 11% lower than the value predicted by a simple rule of mixtures using the CTEs of the constituent phases.