Molecular Dynamics Simulation on Anelasticity under Tensile and Shearing Stresses in Single Component Amorphous Metal

In this study, the nanoscopic deformation behavior in single amorphous during loading-unloading process under tensile and shearing stresses were analyzed by the molecular dynamics method and were compared with the earlier experimental results where an anelastic behavior was not shown in tensile stress but in shearing stress. In this study a clear anelastic deformation was shown in the shearing stress. However, it didn't occur in the tensile stress. This corresponds to the earlier experimental result. When an abrupt strain increase in the stress-strain curve was exhibited, the potential energy and atomic volume has been increased suddenly. This result indicates that the anelastic response of the amorphous metal in the shearing stress was generated by local phase transformation

Mechanical properties of nerve roots and rami radiculares isolated from fresh pig spinal cords

No reports have described experiments designed to determine the strength characteristics of spinal nerve roots and rami radiculares for the purpose of explaining the complexity of symptoms of medullary cone lesions and cauda equina syndrome. In this study, to explain the pathogenesis of cauda equina syndrome, monoaxial tensile tests were performed to determine the strength characteristics of spinal nerve roots and rami radiculares, and analysis was conducted to evaluate the stress-strain relationship and strength characteristics. Using the same tensile test device, the nerve root and ramus radiculares isolated from the spinal cords of pigs were subjected to the tensile test and stress relaxation test at load strain rates of 0.1, 1, 10, and 100 s -1 under identical settings. The tensile strength of the nerve root was not rate dependent, while the ramus radiculares tensile strength tended to decrease as the strain rate increased. These findings provide important insights into cauda equina symptoms, radiculopathy, and clinical symptoms of the medullary cone

Tensile Test of Human Lumbar Ligamentum Flavum: Age-Related Changes of Stiffness

The most common cause of lumbar spinal canal stenosis is age-related degenerative changes. The ligamentum flavum is said to become thicker and stiffer with age, based on several histological and cadaver studies. However, there are no studies determining the age-related changes of the mechanical properties of the ligamentum flavum in live patients. We examined the mechanical properties of the ligamentum flavum of live patients and evaluated the age-related changes. A total of 44 patients undergoing decompression surgery due to lumbar disease at our institute were included. The ligamentum flavum was harvested from the decompression site as a part of a necessary procedure for decompression. The tensile test was performed for the harvested ligamentum flavum within 24 h of harvest. Age-related changes in the stiffness of the ligamentum flavum were evaluated. Age was the only factor that showed a significant correlation with stiffness on multiple regression analysis. We demonstrated that the mechanical properties of the ligamentum flavum change with age