Effect of Sliding Contact on the Structure of Cu-X Nanolaminates

Structural metallic nanolaminates (coatings consisting of alternating layers of different metals) are being explored for applications ranging from high strength foils to wear resistant coatings due to their relatively high hardness. This study seeks to explore how the nanolaminate structure evolves after deposition due to sliding contact. Using two-component Cu-Nb and Cu-Ag model systems (with 20 and 100 nm individual layers), the scratch and wear behavior was characterized using linear reciprocating deformation testing. It was shown that the damage due to sliding (depth of wear track) and coefficient of friction both increased with increasing layer thickness

Data from: Comparative limb bone loading in the humerus and femur of the tiger salamander Ambystoma tigrinum: testing the 'mixed-chain' hypothesis for skeletal safety factors

Locomotion imposes some of the highest loads upon the skeleton, and diverse bone designs have evolved to withstand these demands. Excessive loads can fatally injure organisms; however, bones have a margin of extra protection, called a ‘safety factor’ (SF), to accommodate loads that are higher than normal. The extent to which SFs might vary amongst an animal's limb bones is unclear. If the limbs are likened to a chain composed of bones as ‘links’, then similar SFs might be expected for all limb bones because failure of the system would be determined by the weakest link, and extra protection in other links could waste energetic resources. However, Alexander proposed that a ‘mixed-chain’ of SFs might be found amongst bones if: 1) their energetic costs differ, 2) some elements face variable demands, or 3) SFs are generally high. To test if such conditions contribute to diversity in limb bone SFs, we compared the biomechanical properties and locomotor loading of the humerus and femur in the tiger salamander (Ambystoma tigrinum). Despite high SFs in salamanders and similar sizes of the humerus and femur that would suggest similar energetic costs, the humerus had lower yield stresses, higher mechanical hardness, and larger SFs. SFs were greatest in the anatomical regions where yield stresses were highest in the humerus and lowest in the femur. Such intraspecific variation between and within bones may relate to their different biomechanical functions, providing insight into the emergence of novel locomotor capabilities during the invasion of land by tetrapods

Data from: Comparative limb bone loading in the humerus and femur of the tiger salamander: testing the ‘mixed-chain’ hypothesis for skeletal safety factors

Locomotion imposes some of the highest loads upon the skeleton, and diverse bone designs have evolved to withstand these demands. Excessive loads can fatally injure organisms; however, bones have a margin of extra protection, called a ‘safety factor’ (SF), to accommodate loads that are higher than normal. The extent to which SFs might vary amongst an animal's limb bones is unclear. If the limbs are likened to a chain composed of bones as ‘links’, then similar SFs might be expected for all limb bones because failure of the system would be determined by the weakest link, and extra protection in other links could waste energetic resources. However, Alexander proposed that a ‘mixed-chain’ of SFs might be found amongst bones if: 1) their energetic costs differ, 2) some elements face variable demands, or 3) SFs are generally high. To test if such conditions contribute to diversity in limb bone SFs, we compared the biomechanical properties and locomotor loading of the humerus and femur in the tiger salamander (Ambystoma tigrinum). Despite high SFs in salamanders and similar sizes of the humerus and femur that would suggest similar energetic costs, the humerus had lower yield stresses, higher mechanical hardness, and larger SFs. SFs were greatest in the anatomical regions where yield stresses were highest in the humerus and lowest in the femur. Such intraspecific variation between and within bones may relate to their different biomechanical functions, providing insight into the emergence of novel locomotor capabilities during the invasion of land by tetrapods

Ambystoma Bone Load Stress Components Data

Data for the components of bone stress from the biomechanical model of bone loading during the terrestrial locomotion of salamander

Ambystoma Bone Load Safety Factor Data

Vickers hardness and safety factor data for the biomechanical model of bone loading during the terrestrial locomotion of salamander

Ambystoma Bone Load Kinematic Data

Kinematic data for the biomechanical model of bone loading during the terrestrial locomotion of salamander

README

README.rtf describes the metadata for all files in "Data from: Comparative limb bone loading in the humerus and femur of the tiger salamander: testing the ‘mixed-chain’ hypothesis for skeletal safety factors

Ambystoma Bone Load Stress Data

Bone stress data from the biomechanical model of bone loading during the terrestrial locomotion of salamander

Ambystoma Bone Load Peak Net GRF Data

Peak net ground reaction force data for the biomechanical model of bone loading during the terrestrial locomotion of salamander