The absorption cross section of a number of calcium salts has been assessed at the calcium L edge by measuring the total electron yield (TEY) at the NSLS U13UA beamline. TEY was used because of distortions introduced by instrumentation when using a transmission signal. The effect of these distortions has been evaluated and is presented. The TEY signal was normalized to the incident beam using the signal from a new beam monitor which is detailed here. Comparative spectra are presented for some calcium salts associated with osteoarthritis.
Orthopaedic surgery often involves the insertion of a prosthetic implant. For successful and rapid healing, it is important for the prosthesis to make a close and well integrated bond with the bone tissue. To assist this integration, a number of “biomaterials” are on trial as components in the prosthetic implants. Much work is in progress to determine the phase, composition and density of bone mineral at the bone/biomaterial interface. It is expected that the results of this work can be used to develop synthetic calcium phosphates which can be incorporated in prosthetic implants. The composition of bone and biomaterials has been investigated using techniques such as x-ray diffraction, Infra-red, NMR and EXAFS on homogenized samples. However, these studies do not determine the spatial distribution of the bone mineral, its density, localized mineral phase or cellular integration with biomaterials. Electron microscopy with electron probe microanalysis, light and Infra-red microscopy can indicate the presence of mineral in relation to the tissue morphology, but do not give a spatial measure of the density or chemical phase of the mineral at the sub micron level.
Ultra-thin unstained sections of femoral neck bone from normal and ovariectomised mice were imaged in a scanning transmission x-ray microscope. The images were formed using soft x-ray energies at the calcium L and carbon K edges. The aim of the study was to quantitatively map the calcium, protein and embedding medium in normal and ovariectomised (osteoporotic) mice to compare the quantity and distribution of mineral (via calcium), collagen (via protein) and hydrated content (via embedding medium substitution).A set of seven images were taken of both the normal and ovariectomised mouse sections. These images were processed using x-ray optical constants to produce mass thickness maps. The thickness of the sections from the normal mouse and ovariectomised mice were 205nm and 375nm respectively. The images show embedding medium, protein and calcium maps of near complete sections of the majority of the femoral neck at equivalent neck positions in the normal (la, 2a & 3a) and ovariectomised (lb, 2b & 3b) mouse bone sections.
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