PhD, EngD, MPhil and MSc by research theses (CDS)
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Browsing PhD, EngD, MPhil and MSc by research theses (CDS) by Supervisor "Beckett, Sophie"
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Item Open Access The physical characterisation and composition of archaeological dental calculus(2017) Cooper, K. A.; Beckett, Sophie; Marquez-Grant, NicholasDental calculus is a complex biological material that has been found to provide significant evidence of past population diet, health and habitual activity. It is composed of mineral phases, trace elements, organic species and can have inclusions such as starch granules and microfossils incorporated into its structure. This composition has been found to vary among individuals, although the reasons for this are poorly understood. Despite this, there is a wealth of knowledge that can be gained from analysing this biomineral, especially from archaeological remains. In past populations, the variables that affect composition, such as pharmaceuticals and diet are reduced compared to modern populations. As such the reliance on clinical studies that have investigated dental calculus from modern individuals, may be flawed when considering past populations. The focus of this study was to provide insight about the variation in physical characterisation and composition of archaeological dental calculus. Despite there being an abundance of archaeological dental calculus research, this is the first large scale compositional study of specimens from three separate past populations. In addition, this research is the first study to adopt a non-destructive to destructive approach to archaeological dental calculus analysis. As well, it is the first application of nanocomputed tomography to dental calculus from past populations. Consequently, this study demonstrates the first evidence of accumulation layering that has been detected using non- estructive nano-computed tomography. Furthermore, this research has identified three types of layering in archaeological dental calculus. Due to these findings, it is expected that this research will impact the future of dental calculus analysis, especially when considering dental calculus as a method of mapping an individual’s health, diet or lifestyle in the weeks or months prior to death. The overall results of this thesis demonstrate that some aspects of the morphological, mineralogical and elemental analysis of archaeological dental calculus are inconsistent with clinical literature. The results have also shown that there are some differences between the dental calculus from different archaeological populations which can be related to post-mortem burial conditions.Item Open Access Physiochemical modifications to bone mineral(2016-10-05) Greenwood, Charlene; Rogers, Prof K.; Beckett, SophieBone is a complex composite material consisting of three main components: a mineral phase structurally similar to calcium hydroxyapatite (HAp), an organic matrix containing collagenous and non-collagenous proteins and, water. The complexity of bone has led to an abundance of literature across a wide range of disciplines, which have endeavoured to provide a greater understanding of this material. In particular, heated bone studies are prevalent in biomedicine where heat treatment is often used to sterilise bone material required for xeno– and allo- grafts, in forensic science where species differentiation of unknown heated bone specimens would prove invaluable and in archaeology, where heated bone material often provides information about the cooking and funeral practices of our ancestors. Unfortunately, many of these studies are largely observational and some of the processes and mechanisms associated with heated bone are largely assumed and in some instances ambiguous. Over 1000 biological and synthetic HAp specimens were utilised during this research to investigate the fundamental processes and mechanisms associated with unheated and heated bone. In particular, three controversial areas of bone research were considered: - in vivo HAp crystal size control, the relationship between the organic and mineral components of bone during heat treatment and the confounding effects of cooling on bone mineral during heat treatment. This was achieved by considering the chemical composition of unheated biological and synthetic HAp specimens, and heated bone specimens from various species including human. The results of this thesis demonstrate that an intrinsic rather than extrinsic source may be responsible for in vivo biological HAp crystal size control, a concept which has not previously be considered. The results have also shown bone mineral crystallisation during heat treatment is promoted by the organic matrix and, cooling has an impact on both crystallisation and thermal decomposition of HAp during heat treatment. This research has also questioned the use of current X-ray diffraction (XRD) refinement techniques with nanocrystalline materials such as bone, to determine crystalline size and strain. Further interpretation of the results questioned whether heated bone data is comparable between research groups, whether it was possible to create a time and temperature predictive model for heated bone and whether human bone is statistically different from other bone types when dynamically heated. Due to the fundamental nature of this research, it is expected the results will have an impact across a wide range of disciplines including biomedicine, forensic science and archaeology.