Measurements of Chemical and Mechanical Properties of Rats and Mice Bones under Simulated Space-Like Environment

Changes in elemental composition and mechanical properties of leg bones were determined following hind-limb suspension (HLS) and irradiation of rats and mice. Tibia and Femur were bent with an applied force and corresponding elastic modulus determined. The bones were cross sectioned for elemental composition using Scanning Electron Microscopy with Energy Dispersive capabilities (EDX). The effect of microgravity on bones was evident after 4 days of suspension. There was a strong relationship between the compositional ratios of calcium, carbon, phosphorus and oxygen with the location on the leg. Two methods were used to measure mechanical strength of the bones; a LASER based bending setup (Cantilever) and a 3-point bending setup with sensor to measure bending steps and stepping mechanism. Results showed that the femur bones had Young's modulus between 6 and 18 GN/m. For control groups, it was ~2.5 times larger than that for the HLS group. This clearly points to a less elastic nature of leg bones exposed to ...