Browsing by Author "Ruben, G"

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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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    Micro-computed tomography beamline of the Australian synchrotron: micron-size spatial resolution X-ray imaging
    (MDPI, 2023-01-18) Arhatari, BD; Stevenson, AW; Thompson, D; Walsh, A; Fiala, T; Ruben, G; Afshar, N; Ozbilgen, S; Feng, TT; Mudie, ST; Tissa, P
    The first new beamline of the BRIGHT project—involving the construction of eight new beamlines at the Australian Synchrotron—is the Micro-Computed Tomography (MCT) beamline. MCT will extend the facility’s capability for higher spatial resolution X-ray-computed tomographic imaging allowing for commensurately smaller samples in comparison with the existing Imaging and Medical Beamline (IMBL). The source is a bending-magnet and it is operating in the X-ray energy range from 8 to 40 keV. The beamline provides important new capability for a range of biological and material-science applications. Several imaging modes will be offered such as various X-ray phase-contrast modalities (propagation-based, grating-based, and speckle-based), in addition to conventional absorption contrast. The unique properties of synchrotron radiation sources (high coherence, energy tunability, and high brightness) are predominantly well-suited for producing phase contrast data. An update on the progress of the MCT project in delivering high-spatial-resolution imaging (in the order of micron size) of mm-scale objects will be presented in detail with some imaging results from the hot-commissioning stage. © 2023 The Authors.