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Abstract: As shown previously in Chap. 7, U-containing material (alongside material of a wide range of other compositions) has been observed to exist distributed across the majority of Fukushima Prefecture. This U-rich atmospheric particulate was shown to be some of the smallest to exist (with a mean diameter of 1.07 µm), while containing the fewest additional elemental constituents (i.e. predominantly composed of just U and O).

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Abstract: Synchrotron nanoprobe X-ray absorption (XAS) studies of a potent organo-osmium arene anticancer complex in ovarian cancer cells at subcellular resolution allow detection and quantification of both OsII and OsIII species, which are distributed heterogeneously in different areas of the cells.

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Abstract: The local and systemic dissemination of implant-related derivatives into the body is of great interest to human health. Biological exposures of metal micro/nano-particles, complexes and soluble ions, generated as a consequence of in-service degradation of metallic prosthetics, can result in severe adverse tissues reactions. However, individual reactions are highly variable and are not easily predicted, due to in part a lack of understanding of the properties of the metalstimuli which dictates cellular interactions and toxicity. However, interrogating ultra-dilute metals within fragile, hydrated biological tissues without influencing the native physical and/or chemical composition is challenging. Therefore, a drive for more advanced characterisation techniques of the exogenous metallic particles is required. Here, synchrotron-based X-ray fluorescence spectroscopy (XRF) and X-ray absorption near edge structure (XANES) were deployed to investigate the quantitative spatial distribution and local chemistry of implant-related metal particles within soft tissues. Analytical and experimental steps were outlined and improved when using XRF for greater accuracy in quantification. This included the implications of the matrix composition, the effects of saturation and how the instability in the flux and beam profile affected the measurement. Two post-analytical algorithms were generated to reduce the effects of image artefacts observed frequently in micro-focus XRF images. These methodological advances will have significant positive impact on quantitative XRF. Specifically, the quantitative XRF imaging displayed within this thesis, combined in a multi-institution research effort, influenced the future use of specific metallic implants. The chemistry of exogenous implant-related particles was also investigated, for the first time, using a XANES mapping approach. This enabled twodimensional chemical imaging at a high spatial resolution, allowing superior chemical discrimination of small, isolated, heterogenous features. This method highlighted the unreported variability in metal chemistry associated with orthopaedic implants, which may alter the perceived toxicity of implant derivatives. The results shown within this thesis outline the advantages of using a XANES mapping approach over conventional spectroscopy methods and should be considered when interrogating chemical species of metals in biological environments. Finally, a novel approach to co-locative analysis between exogenous metal particles and the underlying cellular content was developed using a lanthanide-antibody conjugate with XRF. This allowed simultaneous imaging of the native elemental distributions and biological epitopes. The development of this imaging modality is promising for understanding spatial relationships between such components. Collectively, advances within these interrogation methods applied to implant- related products will ultimately help our understanding of associated immunological responses and will generate more appropriate biological exposure models. Additionally, the advantages reported from the development of these techniques can be applied to an array of samples types in many areas of science.

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Abstract: Recent progress has been made in paleontology with respect to resolving pigmentation in fossil material. Morphological identification of fossilized melanosomes has been one approach, while a second methodology using chemical imaging and spectroscopy has also provided critical information particularly concerning eumelanin (black pigment) residue. In this work we develop the chemical imaging methodology to show that organosulfur-Zn complexes are indicators of pheomelanin (red pigment) in extant and fossil soft tissue and that the mapping of these residual biochemical compounds can be used to restore melanin pigment distribution in a 3 million year old extinct mammal species (Apodemus atavus). Synchotron Rapid Scanning X-ray Fluorescence imaging showed that the distributions of Zn and organic S are correlated within this fossil fur just as in pheomelanin-rich modern integument. Furthermore, Zn coordination chemistry within this fossil fur is closely comparable to that determined from pheomelanin-rich fur and hair standards. The non-destructive methods presented here provide a protocol for detecting residual pheomelanin in precious specimens.

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Abstract: Iceland is a highly active source of natural dust. Icelandic dust has the potential to directly affect the climate via dust–radiation interaction and indirectly via dust–cloud interaction, the snow/ice albedo effect and impacts on biogeochemical cycles. The impacts of Icelandic dust depend on its mineralogical and chemical composition. However, a lack of data has prevented an accurate assessment of the role of Icelandic dust in the Earth system. Here, we collected surface sediment samples from five major Icelandic dust hotspots. Dust aerosols were generated and suspended in atmospheric chambers, and PM10 and PM20 fractions were collected for further analysis. We found that the dust samples primarily consist of amorphous basaltic materials ranging from 8 wt % (from the Hagavatn hotspot) to 60 wt %–90 wt % (other hotspots). Samples had relatively high total Fe content (10 wt %–13 wt %). Sequential extraction of Fe to determine its chemical form shows that dithionite Fe (Fe oxides such as hematite and goethite) and ascorbate Fe (amorphous Fe) contribute respectively 1 %–6 % and 0.3 %–1.4 % to the total Fe in Icelandic dust. The magnetite fraction is 7 %–15 % of total Fe and 1 %–2 wt % of PM10, which is orders of magnitude higher than in mineral dust from northern Africa. Nevertheless, about 80 %–90% of the Fe is contained in pyroxene and amorphous glass. The initial Fe solubility (ammonium acetate extraction at pH 4.7) is from 0.08 % to 0.6 %, which is comparable to low-latitude dust such as that from northern Africa. The Fe solubility at low pH (i.e. pH 2) is significantly higher than typical low-latitude dust (up to 30 % at pH 2 after 72 h). Our results revealed the fundamental differences in composition and mineralogy of Icelandic dust from low-latitude dust. We attribute these differences to the low degree of chemical weathering, the basaltic composition of the parent sediments and glacial processes. Icelandic dust contributes to the atmospheric deposition of soluble Fe and can impact primary productivity in the North Atlantic Ocean. The distinct chemical and mineralogical composition, particularly the high magnetite content (1 wt %–2 wt %), indicates a potentially significant impact of Icelandic dust on the radiation balance in the subpolar and polar regions.