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The large public plazas of the ancient Maya were likely swept clear of debris and durable artifacts that could have provided evidence of the ancient anthropogenic activities. However, geochemical residues of food or mineral ores and pigments became affixed to soil and floor particles. These particles chemically bound so that natural movement of water is insufficient to cause them to move, leaving invisible geochemical signatures of ancient activities. This line of study is focused on the relationship between the geospatial distribution of element concentrations and ancient human activities using current laboratory techniques and isopleths, or chemical concentration contour maps, to identify activity areas. Surface samples were collected from ancient plazas at the sites of Kiuic and Sayil in the Puuc Hills of Yucatan and at the site of Caracol Belize. Mehlich II and DTPA extraction procedures were used to determine the elemental concentrations of P, Cu, Fe, Mn, Pb, and Zn. Total elemental levels of additional elements were determined by portable X-ray fluorescence. The objective was to discover geochemical evidence of economic exchange activities at these important site centers. The Kuche Plaza at Kiuic produced evidence of ancient food storage, consumption, or trade activities but such evidence was lacking from the largest open space at the site. The Mirador group at Sayil failed to produce compelling evidence of any market activities. In the Conchita plaza at Caracol there are significant chemical signatures of human activities including evidence of ancient food storage, consumption, or trade activities and evidence of workshop activities potentially including the use production or trade of pigments. Our results from the Conchita plaza suggest ancient marketplace activity, and a geospatial division for the use of the Conchita plaza at Caracol.

Iron is an essential nutrient for energy and DNA replication. Its homeostasis is commonly perturbed by chronic inflammatory mechanisms. Chronic inflammation upregulates a cytokine, hepcidin, that degrades the iron export protein ferroportin. Without a way to export iron into the bloodstream iron availability in blood becomes depleted. Iron depletion in the blood stream hinders erythropoiesis and is termed anemia. Herein I investigate and inhibit the mechanism of hepcidin activation. Inhibition of hepcidin activation has released iron from tissues and alleviated anemic conditions in a cancer model. I have laid the foundation to investigate this pathway in a 3D spheroid model. The results show that hepcidin-25 inhibition is a promising treatment for anemia of cancer. More work needs to be done to confirm efficacy in an in vivo model. In addition to anemia of cancer I have also worked with diabetic rats and investigated their anemic state using common anemia diagnostic methods. I found that in this high fat high sugar diet Wistar rat model anemia was not induced. In addition to my studies on anemia I have investigated the use of portable x-ray fluorescence (pXRF) as an accessible and affordable elemental analysis technique for lateral flow immunoassays and biological samples such as cell lysates and animal tissue. While pXRF shows promising results more work needs to be done to increase its sensitivity and pixel size.

Forensic anthropologists normally examine bone from a variety of medicolegal contexts. The skeletal remains may in some cases be highly fragmented or taphonomically modified, making it difficult to sort bone from non-bone material. In these cases, the forensic anthropologist may rely on microscopic or destructive chemical analyses to sort the material. However, these techniques are costly and time-intensive, prompting the use of nondestructive analytical methods in distinguishing bone and teeth from non-bone materials in a limited number of cases. The proposed analytical techniques are limited in that they rely on an examination of the major elements in the material, and do not sort out all materials with a similar chemical composition to bone/teeth. To date, no methods have been proposed for the use of handheld Xray fluorescence (HHXRF) spectrometry in discriminating human and nonhuman bone/teeth from non-bone materials. The purpose of this research was to develop a method for the use of HHXRF spectrometry in forensic anthropology specifically related to distinguishing human and nonhuman bone and teeth from non-bone materials of a similar chemical composition using multivariate statistical analyses: principal components analysis (PCA), linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), and hierarchical cluster analysis (HCA). This was accomplished in two phases. Phase 1 consisted of a Reliability Test and involved sampling a single human long bone in thirty locations. Multiple spectra were collected at each location to examine the reliability of the instrument in detecting the elements both within a single site and between multiple sites. The results of the Reliability Test indicated that HHXRF consistently detected the major and minor elements found on the surface of a human bone. iv These results were used for Phase 2, designated the Accuracy Test, which involved analyzing a set of materials compiled from the literature to test the accuracy of the technique in discriminating bone (human and nonhuman) and non-bone samples (other biological and nonbiological). The results of the Accuracy Test indicate that osseous and dental tissue can be distinguished from non-bone material of similar chemical composition with a high degree of accuracy (94%) when data is collected from several locations on a sample and analyzed separately during multivariate statistical analyses. Overall, it was not possible to discriminate rock apatite and synthetic hydroxyapatite (synthetic bone) from bone. However, this technique successfully discriminated other non-bone materials that are chemically similar to bone, such as ivory and octocoral, which previous methods focusing on only a comparison of Ca/P ratios were unable to distinguish from bone.

The Neolithic and late Iron Age pottery from the settlement site of Pool, Sanday, Orkney, was studied on two levels. Firstly, a morphological and technological study was carried out to establish a sequence for the site. Secondly an assessment was made of the usefulness of X-ray Fluorescence Analysis, Inductively Coupled Plasma Spectrometry and Petrological analysis to coarse ware studies, using the Pool assemblage as a case study. Recording of technological and typological attributes allowed three phases of Neolithic pottery to be identified. The earliest phase included sherds of Unstan Ware. This phase was followed by an assemblage characterised by pottery with incised decoration, which was stratified below a traditional Grooved Ware assemblage. The change in pottery styles and manufacturing methods with the Grooved Ware indicated that it evolved elsewhere. Grass tempered and burnished pottery characterised the Iron Age assemblage. Pottery samples from all phases of the site were analysed by XRF and ICPS. In addition, pottery from late Iron Age sites in the area was analysed for comparison with the Pool Iron Age pottery. XRF and ICPS analyses did not distinguish between either different phases at Pool or different Orcadian sites. This was attributed to the similarities in geological deposits over much of Orkney and the variations which can occur within a clay source. A clay survey was carried out in the vicinity of the site, and samples taken for comparison with the Pool pottery. Identification of rocks and minerals in thin section, and grain-size analysis, indicated that the Pool pottery was made locally to the site, and that both primary and secondary clays were used. It was concluded that petrological analysis is more suitable than elemental analysis in the study of coarse wares. / Science-based Archaeology'Committee of the Science and Engineering Research Council.

Trace elements are involved in many biological processes and serve important functions to maintain the normal development of the central nervous system (CNS). In the CNS, iron (Fe), copper (Cu), and zinc (Zn) are some of the most important elements that play critical roles as catalysts, cofactors, and structural components for many cellular enzymes and proteins. The deficiency or excess of these metals may lead to various neurological disorders. Demyelination is a condition of loss of myelin and leads to neurological diseases like Multiple Sclerosis. Myelin consists of transition metals and hence it would be interesting to study concentrations of these elements in normal and demyelinated models. X-Ray Fluorescence (XRF) is a popular non-destructive technique applied in trace element studies. The principle involves exciting a sample and detecting characteristic X-rays, which provide information on elemental concentrations in the sample. In the present studies the feasibility of XRF for trace element studies was explored. A total of 120 samples of brain and spinal cord tissues were collected from Long Evans (control) and Long Evans Shaker (dysmyelinated)–an incomplete formation of myelin sheaths–rats at ages of 3 weeks and 16 weeks. The samples were excited using x-rays from an Energy Dispersive X-Ray Diffraction (EDXRF) set-up. The spectral data was collected using an Silicon Drift Detector (SDD) and the resultant data were analysed to see if statistically significant changes in concentrations were present in the samples. The results were discussed and suggestions for future work were made. / Thesis / Master of Science (MSc)

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<p>Arsenic (As) is an element that is well known for its toxic capabilities. It is odorless and colorless and is known to contaminate the drinking water of populations in several parts of the world. Routine monitoring of arsenic exposure is usually performed with urine, hair or nail, where samples are collected for laboratory analysis. Arsenic’s strong affinity to keratin rich tissues make skin another possible measurement site, in addition to the latter two tissues mentioned above. In some cases, skin samples are extracted for analysis. This is painful and invasive and is not ideal for <em>in vivo</em> monitoring of arsenic. The ability to quantify elemental concentration non-destructively is the major calling card of x-ray fluorescence (XRF). To that end, work was started on development of XRF detection systems for arsenic. The technique has shown promise for other elements and dramatic improvements in As detection capabilities were previously found when going from a radioisotope-based x-ray source to an x-ray tube based approach.</p> <p>This thesis documents the comparison of three x-ray tube based detection systems intended for the measurement of arsenic in skin. Two benchtop systems were used, with a) extended development of the previously assembled system and b) the first use of a separate detection system. Two handheld x-ray analyzers (portable detection systems) were also investigated in stand mode, where they were attached to a purpose-built mounting stand, provided by the manufacturer, during all analysis. Polyester resin phantoms were used to model arsenic in skin and a nylon backing was used to represent as bulk tissue behind skin. During the course of the work, modifications were made to the laboratory setup associated with the benchtop approaches.</p> <p>A benchtop polychromatic Mo anode x-ray tube based x-ray fluorescence (XRF) detection system was the first system used in this work. Through modifications to the existing design of the system, the lowest minimum detection limit (MDL) achievable was found to be (0.611±0.001) ppm normalized to gross scatter, where ppm is ug of arsenic per gram of dry weight (resin). The measurement time was ~1800 seconds real time. The equivalent (skin) and whole body effective doses delivered were (19±3) uSv and (163±47) uSv respectively. The corresponding direct (un-normalized) MDL was (0.499±0.002) ppm, in agreement with that found previously. Modifications to the system allowed a reduction in the localized effective dose delivered, to achieve this MDL, from (0.64±0.03) uSv previously to (0.14±0.04) uSv here.</p> <p>Next, the current work investigated two handheld x-ray analyzers provided by InnovX. A PiN diode detector based Alpha 4000S model unit (W anode x-ray tube) and a Silicon Drift Detector (SDD) based Delta model (Au anode x-ray tube). Both units were operated in benchtop mode: they were mounted in a stand and a phantom was placed on a kapton exit window. The lowest gross-scatter normalized and direct detection limit with the Alpha 4000S unit was (1.649±0.002) ppm and (1.651±0.002) ppm respectively. The equivalent and whole body effective doses delivered were found to be (9.4±2.2) mSv and (94±22) uSv respectively. The localized effective dose was (6.4±1.5) X 10^-3 uSv. By comparison, the Delta unit produced a gross-scatter and direct normalized detection limit of (0.570±0.002) ppm and (0.558±0.002) ppm respectively. The equivalent dose delivered was found to be (19.0±9.0) mSv. The corresponding localized and whole body effective doses delivered were (9.7±4.6) X 10^-3 uSv and (190±90) uSv respectively.</p> <p>The last system used in the current research was a monochromatic Ag anode x-ray tube based XRF setup. A doubly curved crystal (DCC) was used to select the Ag K-alpha line and focused the beam to a spot size of mm² at the focal length. The phantoms were placed at a farther distance where the beam had expanded to a larger area. The lowest Compton scatter normalized detection limit with the Si(Li) detector was found to be (0.696±0.002) ppm. After characterizing its performance in a range of energies, a silicon drift detector was also used on this system. It had the benefit of higher throughput capabilities and superior resolution. The housing of the detector was sufficiently small that it could be placed closer to the phantom surface than the Si(Li) detector. The lowest Compton-scatter normalized detection limit with the SDD was (0.441±0.003) ppm in 1800 seconds real time. The equivalent dose was found to be (11±2) mSv and the localized and whole body effective doses were found to be (3.92±0.87) X 10^-3 uSv and (110±23) uSv respectively. A significantly lower system dead time was observed with the SDD. Finally, Monte Carlo simulations of the system were performed to evaluate the performance of three ratios when their phantom measurement values were compared against simulations of skin. Results were found to be in agreement to withinin vivo concentration of arsenic in skin (ICRP).</p> <p>Finally, EDXRF measurements were performed on bulk cores of skin, <em>ex vivo</em>. While it was not possible to detect arsenic in the samples, due to the samples being collected from members of the public as opposed to an exposed population, a depth profile of numerous skin samples, starting from the surface and running straight down, was obtained for calcium, iron and copper.</p> / Doctor of Philosophy (PhD)