observed consisted of a group of eleven breaks and a group of fourteen breaks. The large clusters were observed at the highest load, at sites with no prior breaks, indicating they occurred within a relatively narrow load range. No strong correlation was found between the location of matrix damage and fibre breaks. The data achieved has been made available online at www.materialsdatacentre.com/ for ongoing model development and validation.

Abstract:The relative roles of the superoxide and hydroxyl rad icals in oxidative stress-induced neuronal damage were investigated using organotypic hippocampal slice cultures. Cultures exposed to 100 ftM duroquinone, a superoxide-generating compound, for 3 h developed CAl -selective lesions over a period of 24 h. The damage accounted for '-64% of the CAl subfield, whereas CA3 showed just 6% damage, a pattern of damage comparable to that observed following hypoxia!ischaemia. Duroquinone-induced damage was attenuated by a spin-trap agent. In contrast, hydroxyl radical-mediated damage, generated by exposure to 30 jiM ferrous sulphate for 1 h, resulted in a CA3-dominant lesion. The damage developed over 24 h, similar to that observed with duroquinone, but with -45% damage in CA3 compared with only 7% in CAl. These data demonstrate a selective vulnerability of the CAl pyramidal neurones to superoxide-induced damage and suggest that of the free radicals generated following hypoxia/ischaemia, superoxide, rather than hydroxyl radical, is instrumental in producing neuronal damage.

This article presents the first use of synchrotron radiation computed tomography (SRCT) to achieve sub-micron resolution of damage in aerospace grade carbon fiber—epoxy composites. The structure and interaction of the damage can be visualized in 3-D on a scale not previously observed in practical engineering configurations. The ability to detect and accurately measure features down to individual fiber breaks provides a valuable platform for future research; from the rigorous evaluation of damage models to understanding the fundamental physical mechanisms governing crack growth in composites. In particular the key role of intra-laminar cracks and delaminations in localizing fiber fractures is unambiguously identified for the first time.

No abstract