Browsing by Author "Ryan, CG"

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    The application of synchrotron radiation induced X-ray emission in the measurement of zinc and lead in Wistar rat ameloblasts
    (Elsevier, 2007-10) Arora, M; Kennedy, BJ; Ryan, CG; Boadle, RA; Walker, DM; Harland, CL; Lai, B; Cai, ZH; Vogt, S; Zoellner, H; Chan, SWY
    The development of analytical techniques for the measurement of trace elements in cellular compartments of developing teeth remains an important methodological issue in dental research. Recent advances in third generation synchrotron facilities have provided high brilliance X-ray sources that can be effectively used to study trace element distributions in small spatial regions with low detection limits. The present study describes for the first time the application of synchrotron radiation induced X-ray emission (SRIXE) in measuring the distribution of zinc and lead in the ameloblasts of developing Wistar rat teeth. Wistar rats were fed a standard rat diet, containing the normal dietary requirements of zinc, ad libitum and exposed to 100ppm of lead in drinking water. Resin embedded sections of first mandibular molars were analysed using a 13.3keV incident monochromatic X-ray beam focussed to a 0.2μm spot. Characteristic X-rays arising from the entire thickness of the sample were measured using an energy dispersive detector for quantitative analysis of elemental concentrations. The results showed that intranuclear concentrations of zinc were greater than levels in the cytoplasm. Furthermore, nuclear and cytoplasmic concentrations of zinc in the maturation stage (742±27 and 424±25ppm, respectively) were significantly higher than the zinc levels observed in the nucleus and cytoplasm of presecretory stage ameloblasts (132±10 and 109±10ppm, respectively) (p<0.05). A clear lead signal above the background was not detected in the ameloblasts and lead concentrations could only be reliably measured in the developing enamel. Overall, SRIXE was an effective method of studying the spatial distribution of zinc in the cells of developing teeth and offered a unique combination of sub-micron spatial resolution and parts-per-million detection limits (0.8–1 and 0.6–1ppm for zinc and lead, respectively). © 2007, Elsevier Ltd.
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    Direct imaging of endogenous biometal distributions within millimetre-scale organisms at micrometre resolution – x-ray fluorescence tomography
    (Australian Microscopy and Microanalysis Society, 2016-02-04) de Jonge, MD; Ruben, G; Mayo, SS; Ryan, CG; Kirkham, R; Howard, DL; Paterson, DJ
    First-row transition metals are required for all forms of life on earth. The high reactivity of these elements means that an array of mechanisms has evolved to regulate key processes governing their transport and binding action. Tracking metals within biological tissue is non-trivial; tagging approaches suffer from lack of specificity, and can fail to find strongly-bound species; in addition, tags can interfere with normal biochemistry. Electron microscopy provides stupendous resolution, but probes miniscule volumes due to the short penetration of electrons. With μM sensitivity, X-ray Fluorescence Microscopy (XFM) can probe endogenous metal concentrations at resolutions at the μm length scale. Elemental maps are quantitative. With penetration depth and depth of field well matched at around 0.5 mm, the method can be up-scaled to 3-D visualisations via tomography. Here we report on our application of X-ray fluorescence tomography of Zn, Cu, Fe, and Mn in C. elegans and discuss recent progress in developing self-absorption corrections that will enable accurate mapping of light elements.
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    Germanium speciation in experimental and natural sphalerite: Implications for critical metal enrichment in hydrothermal Zn-Pb ores
    (Elsevier, 2023-02-01) Liu, WH; Mei, Y; Etschmann, BE; Glenn, M; MacRae, CM; Spinks, SC; Ryan, CG; Brugger, J; Paterson, DJ
    The critical metal germanium (Ge) is recovered as a by-product of mining other commodities, such as zinc and thermal coal. We investigated the Ge incorporation mechanism in sphalerite synthesized under hydrothermal conditions like those of sediment-hosted Zn-Pb deposits. Sphalerite ± galena ± barite formed via reactions of Ge ± Fe ± Cu ± Ba-bearing brine with calcite and reduced sulfur at 200 °C and water vapor-saturated pressure. The products were examined using backscattered electron (BSE) imaging, electron probe microanalysis (EPMA), electron backscattered diffraction (EBSD), synchrotron X-ray fluorescence (SXRF) and micro-X-ray absorption near-edge structure (μ-XANES). We show that Ge(IV) is incorporated into sphalerite and bonded with reduced sulfur, both in the experimental sphalerite and in natural zinc ore samples from the MacArthur River Zn-Pb-Ag deposits, Australia. Copper K-edge XANES spectra show that copper occurs as Cu(I) in the experimental sphalerite, consistent with previous studies on Cu in natural sphalerite. The experiments reveal that Ge(IV) substitution in sphalerite occurs with and without the presence of other metal ions (e.g., Cu(I)), indicating that Ge(IV) substitution can be accommodated via charge balance by vacancies as well as by coupled substitution in the synthesized sphalerite. Ab initio quantum chemical simulations confirm that sphalerite can readily accommodate Ge via charge balance by vacancies and by coupled substitutions, with the crystal structure and average Zn-S, Zn-Zn, S-S distances retained when replacing > 3 mol% of the Zn sites with Ge(IV), Ge(II), Cu(I) or Fe(II), demonstrating the resilience and flexibility of the sphalerite crystal structure. These Ge incorporation mechanisms explain the previous observations of multiple ways of Ge incorporation in natural sphalerite. The study provides experimental and molecular simulation insights for understanding the processes related to the formation and extraction of Ge in zinc ores. 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-NDlicense
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    Microspectroscopy beamline at the Australian Synchrotron
    (American Institute of Physics, 2007-01-19) Paterson, DJ; Boldeman, JW; Cohen, DD; Ryan, CG
    This dedicated beamline will provide sub‐micron spatial resolution with the highest flux possible and an energy tuning range of 4.7–25 keV using an in‐vacuum undulator source. It will combine 2D mapping with μ‐XRF, μ‐XANES and μ‐XAFS for elemental and chemical analysis to solve scientific problems that can only be understood using sub‐micron resolutions. The primary beamline design goal is to achieve sub‐micron spatial resolution, 100–200 nm, at energy resolutions approaching 1/10000. This spatial resolution will be achieved without a major compromise to the flux, as the beamline will simultaneously achieve detection sensitivities to sub‐ppm levels. The beamline will have the flexibility to trade‐off one parameter against gains in certain attributes, as dictated by the needs of the application. Fresnel zone plates are intended for the highest resolution applications, while the KB mirrors are shall be used for applications where achromatic focusing and high sensitivity are required. The beamline design will accommodate a diverse range of applications with greatly contrasting sample formats, sample composition and anticipated detector count rates. © 2007 American Institute of Physics.
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    Microspectroscopy beamline at the Australian synchrotron: design and capabilities
    (XRM Conference, 2008-07) Paterson, DJ; de Jonge, MD; McKinlay, J; Ryan, CG; Cohen, DD
    A hard x-ray micro-nanoprobe is being constructed at the Australian Synchrotron [1] to provide sub-micron spatial resolution across an energy range of 4.5–25 keV. The SXM will combine 2D mapping with μ-XRF, μ-XANES and μ-XAFS for elemental and chemical microanalysis. The primary design goal is to achieve sub-100 nm spatial resolution with DE/E ~10-4, and sub-ppm elemental sensitivity. The optical design is a novel “all horizontal” scheme [2]. Interchangeable Fresnel zone plates and Kirkpatrick-Baez mirrors will be used. An advanced fluorescence detector developed by BNL [3] and CSIRO [4] featuring a large solid-angle planar silicon array will enable count rates up to 108 events/sec and real-time processing with deconvoluted image projection. A differential phase contrast detection scheme [5] will be employed for quantitative measurement of soft matter [6]. The Microspectroscopy Beamline will commence operation in late 2008 and will accommodate a diverse range of environmental, biological and materials science applications to cater for the broad requirements of the Australian community. The design, anticipated performance and research applications will be discussed.
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    Polycrystalline materials analysis using the Maia pixelated energy-dispersive x-ray area detector
    (Cambridge University Press, 2017-09-26) Kirkwood, HJ; De Jonge, MD; Howard, DL; Ryan, CG; van Riessen, GA; Hofmann, F; Rowles, MR; Paradowska, AM; Abbey, B
    Elemental, chemical, and structural analysis of polycrystalline materials at the micron scale is frequently carried out using microfocused synchrotron X-ray beams, sometimes on multiple instruments. The Maia pixelated energy-dispersive X-ray area detector enables the simultaneous collection of X-ray fluorescence (XRF) and diffraction because of the relatively large solid angle and number of pixels when compared with other systems. The large solid angle also permits extraction of surface topography because of changes in self-absorption. This work demonstrates the capability of the Maia detector for simultaneous measurement of XRF and diffraction for mapping the short- and long-range order across the grain structure in a Ni polycrystalline foil. Copyright © International Centre for Diffraction Data 2017
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    Simultaneous X-ray diffraction, crystallography and fluorescence mapping using the Maia detector
    (Elsevier, 2018-02-01) Kirkwood, HJ; de Jonge, MD; Muránsky, O; Hofmann, F; Howard, DL; Ryan, CG; van Riessen, GA; Rowles, MR; Paradowska, AM; Abbey, B
    Interactions between neighboring grains influence the macroscale behavior of polycrystalline materials, particularly their deformation behavior, damage initiation and propagation mechanisms. However, mapping all of the critical material properties normally requires that several independent measurements are performed. Here we report the first grain mapping of a polycrystalline foil using a pixelated energy-dispersive X-ray area detector, simultaneously measuring X-ray fluorescence and diffraction with the Maia detector in order to determine grain orientation and estimate lattice strain. These results demonstrate the potential of the next generation of X-ray area detectors for materials characterization. By scanning the incident X-ray energy we investigate these detectors as a complete solution for simultaneously mapping the crystallographic and chemical properties of the sample. The extension of these techniques to broadband X-ray sources is also discussed. © 2017 Acta Materialia Inc. Published by Elsevier Ltd.