Browsing by Author "Rogers, Keith D."
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Item Open Access Age related changes of rib cortical bone matrix and the application to forensicage-at-death estimation(Nature Publishing Group, 2021-01-22) Bonicelli, Andrea; Zioupos, Peter; Arnold, Emily; Rogers, Keith D.; Xhemali, Bledar; Kranioti, Elena F.Forensic anthropology includes, amongst other applications, the positive identification of unknown human skeletal remains. The first step in this process is an assessment of the biological profile, that is: sex, age, stature and ancestry. In forensic contexts, age estimation is one of the main challenges in the process of identification. Recently established admissibility criteria are driving researchers towards standardisation of methodological procedures. Despite these changes, experience still plays a central role in anthropological examinations. In order to avoid this issue, age estimation procedures (i) must be presented to the scientific community and published in peer reviewed journals, (ii) accurately explained in terms of procedure and (iii) present clear information about the accuracy of the estimation and possible error rates. In order to fulfil all these requirements, a number of methods based on physiological processes which result in biochemical changes in various tissue structures at the molecular level, such as modifications in DNA-methylation and telomere shortening, racemization of proteins and stable isotopes analysis, have been developed. The current work proposes a new systematic approach in age estimation based on tracing physicochemical and mechanical degeneration of the rib cortical bone matrix. This study used autopsy material from 113 rib specimens. A set of 33 parameters were measured by standard bio-mechanical (nanoindentation and microindentation), physical (TGA/DSC, XRD and FTIR) and histomorphometry (porosity-ImageJ) methods. Stepwise regressions were used to create equations that would produce the best ‘estimates of age at death’ vs real age of the cadavers. Five equations were produced; in the best of cases an equation counting 7 parameters had an R2 = 0.863 and mean absolute error of 4.64 years. The present method meets all the admissibility criteria previously described. Furthermore, the method is experience-independent and as such can be performed without previous expert knowledge of forensic anthropology and human anatomy.Item Open Access Combined X-ray diffraction and absorption tomography using a conical shell beam(2019-07-15) Shevchuk, Alex; Evans, J. Paul O.; Dicken, A. J.; Elarnaut, D.; Downes, D.; Godber, S. X.; Rogers, Keith D.We combine diffraction and absorption tomography by raster scanning samples through a hollow cone of pseudo monochromatic X-rays with a mean energy of 58.4 keV. A single image intensifier takes 90x90 (x,y) snapshots during the scan. We demonstrate a proof-of-principle of our technique using a heterogeneous three-dimensional (x,y,z) phantom (90x90x170 mm3) comprised of different material phases, i.e., copper and sodium chlorate. Each snapshot enables the simultaneous measurement of absorption contrast and diffracted flux. The axial resolution was ~1 mm along the (x,y) orthogonal scan directions and ~7 mm along the z-axis. The tomosynthesis of diffracted flux measurements enable the calculation of d-spacing values with ~0.1 Å full width at half maximum (FWHM) at ~2 Å. Thus the identified materials may be color-coded in the absorption optical sections. Characterization of specific material phases is of particular interest in security screening for the identification of narcotics and a wide range of homemade explosives concealed within complex “everyday objects.” Other potential application areas include process control and biological imaging.Item Open Access Conical shell X-ray beam tomosynthesis and micro-computed tomography for microarchitectural characterisation(Springer Nature, 2023-12-06) Arnold, Emily; Elarnaut, Farid; Downes, David; Evans, J. Paul O.; Greenwood, Charlene; Rogers, Keith D.Bone quality is commonly used to diagnose bone diseases such as osteoporosis, with many studies focusing on microarchitecture for fracture prediction. In this study a bovine distal femur was imaged using both micro-computed tomography (µCT) and tomosynthesis using focal construct geometry (FCG) for comparison of microarchitectural parameters. Six regions of interest (ROIs) were compared between the two imaging modalities, with both global and adaptive methods used to binarize the images. FCG images were downsampled to the same pixel size as the µCT images. Bone morphometrics were determined using BoneJ, for each imaging modality, binarization technique and ROI. Bone area/total area was found to have few significant differences between FCG and µCT (p < 0.05 for two of six ROIs). Fractal Dimension had only one significant difference (p < 0.05 for one of six ROIs) between µCT and downsampled FCG (where pixel size was equalized). Trabecular thickness and trabecular spacing were observed to follow trends as observed for the corresponding µCT images, although many absolute values were significantly different (p < 0.05 for between one and six ROIs depending on image types used). This study demonstrates the utility of tomosynthesis for measurement of microarchitectural morphometrics.Item Open Access Investigating pair distribution function use in analysis of nanocrystalline hydroxyapatite and carbonate-substituted hydroxyapatite(International Union of Crystallography, 2022-04-14) Arnold, Emily; Keeble, Dean S.; Evans, J. Paul O.; Greenwood, Charlene; Rogers, Keith D.Hydroxyapatite (HA) is a complex material, which is often nanocrystalline when found within a biological setting. This work has directly compared the structural characteristics derived from data collected using a conventional laboratory-based X-ray diffractometer with those collected from a dedicated pair distribution function (PDF) beamline at Diamond Light Source. In particular, the application of PDF analysis methods to carbonated HA is evaluated. 20 synthetic samples were measured using both X-ray diffraction (XRD) and PDFs. Both Rietveld refinement (of laboratory XRD data) and real-space refinement (of PDF data) were used to analyse all samples. The results of Rietveld and real-space refinements were compared to evaluate their application to crystalline and nanocrystalline hydroxyapatite. Significant relationships were observed between real-space refinement parameters and increasing carbonate substitution. Understanding the local order of synthetic hydroxyapatite can benefit several fields, including both biomedical and clinical settings.Item Open Access New insights into the application of pair distribution function studies to biogenic and synthetic hydroxyapatites(Springer, 2020-11-11) Arnold, Emily; Keeble, Dean S.; Greenwood, Charlene; Rogers, Keith D.Biogenic and synthetic hydroxyapatites are confounding materials whose properties remain uncertain, even after years of study. Pair distribution function (PDF) analysis was applied to hydroxyapatites in the 1970’s and 1980’s, but this area of research has not taken full advantage of the relatively recent advances in synchrotron facilities. Here, synchrotron X-ray PDF analysis is compared to techniques commonly used to characterise hydroxyapatite (such as wide angle X-ray scattering, Fourier-transform infrared spectroscopy and thermogravimetric analysis) for a range of biogenic and synthetic hydroxyapatites with a wide range of carbonate substitution. Contributions to the pair distribution function from collagen, carbonate and finite crystallite size were examined through principal component analysis and comparison of PDFs. Noticeable contributions from collagen were observed in biogenic PDFs when compared to synthetic PDFs (namely r < 15 Å), consistent with simulated PDFs of collagen structures. Additionally, changes in local structure were observed for PDFs of synthetic hydroxyapatites with differing carbonate content, notably in features near 4 Å, 8 Å and 19 Å. Regression models were generated to predict carbonate substitution from peak position within the PDFs.Item Open Access Thermally dynamic examination of local order in nanocrystalline hydroxyapatite(Elsevier, 2022-08-13) Arnold, Emily; Gosling, Sarah; Davies, Samantha K.; Cross, Hannah L.; Evans, Paul; Keeble, Dean S.; Greenwood, Charlene; Rogers, Keith D.The main mineral component of bone is hydroxyapatite, a commonly nanocrystalline material which presents many challenges for those trying to characterize it. Here, local structure is analyzed using X-ray total scattering for synthetic samples, to enable a better understanding of the nanocrystalline nature of hydroxyapatite. Two samples were measured dynamically during heat treatment from 25°C to 800°C, and were analyzed using small box modelling. Analysis of sequential measurements when dwelling at key temperatures showed a significant relationship between time and temperature, indicating a process occurring more slowly than thermal expansion. This indicates a decrease in B-type CO32- substitution between 550°C and 575°C and an increase in A-type CO32- substitution above 750°C. A greater understanding of local, intermediate, and long-range order of this complex biomineral during heat treatment can be of interest in several sectors, such as in forensic, biomedical and clinical settings for the study of implant coatings and bone diseases including osteoporosis and osteoarthritis.Item Open Access The use of μCT and fractal dimension for fracture prediction in osteoporotic individuals(Elsevier, 2019-12-11) Arnold, Emily; Clement, John; Rogers, Keith D.; Garcia-Castro, Fabio; Greenwood, CharleneOsteoporosis (OP) is a widespread condition with commonly associated fracture sites at the hip, vertebra and wrist. This study examines the effects of age and osteoporosis on bone quality by comparing the efficacy of using parameters which indicate bone quality (both traditional clinical parameters such as bone mineral density (BMD), as well as apparent Young's modulus determined by finite element analysis, among others) to predict fracture. Non-fracture samples were collected from the femoral heads of 83 donors (44 males, 39 females), and fracture samples were obtained from the femoral heads of 17 donors (female). Microarchitectural parameters (Bone Volume/Total Volume [BV/TV], Bone Surface/Bone Volume [BS/BV], Tissue Mineral Density [TMD, etc.]) were measured from μCT of each sample as well as 2D and 3D fractal dimension (D2D and D3D respectively). A cube was cropped from μCT images and an isotropic hexahedral element was assigned to each voxel. Finite element analysis was used to calculate the Young's modulus for each sample. Overall, values for microarchitectural characteristics, fractal dimension measurements and Young's Modulus were consistent with values within literature. Significant correlations are observed between age and BV/TV for non-fracture males and females, as well as between age and volumetric BMD (vBMD) for the same groups. Significant differences are present between age-matched non-fracture and fracture females for BV/TV, BS/BV, vBMD, TMD, D2D, D3D, (p < 0.01 for all). Properties which are not age dependent are significantly different between age-matched non-fracture and fracture specimens, indicating OP is a disease, and not just an accelerated aging process.