Browsing by Author "Jones, MWM"

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    Havre 2012 pink pumice is evidence of a short-lived, deep-sea, magnetite nanolite-driven explosive eruption
    (Goldschmidt, 2022-07-16) Knafelc, J; Byran, SE; Jones, MWM; Gust, D; Mallmann, G; Cathey, H; Berry, A; Ferré, EC; Howard, DL
    The Havre 2012 deep-sea eruption produced a massive pumice raft (~1.2 km3) at the sea surface from a volcano that sits 900 mbsl (~9.6 MPa) in the Kermadec Arc. Lava flows/domes and a field of sunken seafloor pumice were also emplaced across the summit during the eruption. Havre raft and seafloor pumice are considered to have erupted contemporaneously and as part of an effusive eruption due their similarity in appearance and bulk chemistry. A distinctive feature of the raft is the common occurrence of pink pumice. Pink pumice has been reported from subaerial explosive eruptions, and results from high-temperature atmospheric iron-oxidation (> 700 °C). The pink raft pumice therefore poses problems given the deep water setting that is assumed to prevent eruption explosivity and the effusive eruption model for the 2012 eruption. Here, pink pumice is experimentally produced by heating white Havre raft pumice for several minutes in air at temperatures between 675-900°C (Fig. 1). The degree of reddening in experimental pumices increases with increased temperatures and times, resulting in a similar spectrum of colouration observed in natural pink raft pumice. The origin of the pink colouration was then investigated using several microanalytical techniques including X-ray Fluorescence Microscopy (XFM), Fe X-ray Absorption Near Edge structures (Fe-XANES), EPMA, rock magnetics, and TEM imaging. We found that white and pink raft pumice contain abundant magnetite nanolites/microlites and higher amounts of hematite in the pink pumice. In contrast, no magnetite nanolites or hematite occurs in the seafloor pumice. Magnetite nanolites line vesicle walls of pink raft pumice where the colour is microscopically localized. This provides evidence the magnetite nanolites are oxidizing to hematite and also acted as nucleation sites for enhanced volatile exsolution. Our results demonstrate a short-lived but powerful explosive eruption phase occurred during the 2012 eruption that penetrated the water column allowing hot pyroclasts to oxidize in air (Fig. 2). In light of these results the known depth limits for explosive eruptions (~10 MPa) in the marine realm need to be reassessed and we suggest pink pumice can be an indicator of magnetite nanolite-driven explosive eruptions.
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    High speed free-run ptychography at the Australian Synchrotron
    (Australian Nuclear Science and Technology Organisation, 2021-11-26) Kewish, CM; Jones, MWM; van Rissen, GA; Phillips, NW; Hinsley, GN; Schrank, CE; Afshar, J; Reinhardt, J; de Jonge, MA
    The Australian Synchrotron X-ray Fluorescence Microscopy (XFM) beamline has recently implemented fast scanning ptychography, a scanning X-ray diffraction microscopy method. Ptychography creates super-resolution images from transmitted microdiffraction patterns acquired as the sample is scanned through the beam. Highspeed detectors and high-performance computers are required to iteratively reconstruct these complex images. The experimental methods and reconstruction algorithms have significantly evolved over the last decade and a half into a mature and user-friendly complementary imaging method to XFM. Here we present the implementation of high speed ptychography at the XFM beamline, which includes a free run data collection mode where detector dead time is eliminated, and the scan time is optimized. We show that free-run data collection is viable for fast and high-quality ptychography by demonstrating extremely high data rate acquisition covering areas up to 352,000 μm2 at up to 140 μm2/s, with 18× spatial resolution enhancement compared to the beam size. With these improvements, ptychography at velocities up to 250 μm/s is approaching speeds compatible with fast-scanning X-ray fluorescence microscopy. The combination of these methods provides morphological context for elemental and chemical information, enabling unique scientific outcomes. © The Authors
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    High-speed free-run ptychography at the Australian Synchrotron
    (International Union of Crystallography, 2022-03) Jones, MWM; van Riessen, GA; Phillips, NW; Schrank, CE; Hinsley, GN; Afshar, N; Reinhardt, J; de Jonge, MD; Kewish, CM
    Over the last decade ptychography has progressed rapidly from a specialist ultramicroscopy technique into a mature method accessible to non-expert users. However, to improve scientific value ptychography data must reconstruct reliably, with high image quality and at no cost to other correlative methods. Presented here is the implementation of high-speed ptychography used at the Australian Synchrotron on the XFM beamline, which includes a free-run data collection mode where dead time is eliminated and the scan time is optimized. It is shown that free-run data collection is viable for fast and high-quality ptychography by demonstrating extremely high data rate acquisition covering areas up to 352 000 μm2 at up to 140 μm2 s-1, with 13x spatial resolution enhancement compared with the beam size. With these improvements, ptychography at velocities up to 250 μm s-1 is approaching speeds compatible with fast-scanning X-ray fluorescence microscopy. The combination of these methods provides morphological context for elemental and chemical information, enabling unique scientific outcomes. © The Authors - Open Access CC-By Licence
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    Placental element content assessed via synchrotron-based x-ray fluorescence microscopy identifies low molybdenum concentrations in foetal growth restriction, postdate delivery and stillbirth
    (MDPI, 2024-08-03) Foteva, V; Maiti, K; Fisher, JJ; Qiao, Y; Paterson, DJ; Jones, MWM; Smith, R
    Placental health and foetal development are dependent upon element homeostasis. Analytical techniques such as mass spectroscopy can provide quantitative data on element concentrations in placental tissue but do not show spatial distribution or co-localisation of elements that may affect placental function. The present study used synchrotron-based X-ray fluorescence microscopy to elucidate element content and distribution in healthy and pathological placental tissue. The X-ray fluorescence microscopy (XFM) beamline at the Australian Synchrotron was used to image trace metal content of 19 placental sections from healthy term (n = 5, 37–39 weeks), foetal growth-restricted (n = 3, <32 weeks, birth weight <3rd centile), postdate (n = 7, >41 completed weeks), and stillbirth-complicated pregnancies (n = 4, 37–40 weeks). Samples were cryo-sectioned and freeze-dried. The concentration and distribution of fourteen elements were detected in all samples: arsenic, bromine, calcium, chlorine, copper, iron, molybdenum, phosphorous, potassium, rubidium, selenium, strontium, sulphur, and zinc. The elements zinc, calcium, phosphorous, and strontium were significantly increased in stillbirth placental tissue in comparison to healthy-term controls. Strontium, zinc, and calcium were found to co-localise in stillbirth tissue samples, and calcium and strontium concentrations were correlated in all placental groups. Molybdenum was significantly decreased in stillbirth, foetal growth-restricted, and postdate placental tissue in comparison to healthy-term samples (p < 0.0001). Synchrotron-based XFM reveals elemental distribution within biological samples such as the placenta, allowing for the co-localisation of metal deposits that may have a pathological role. Our pilot study further indicates low concentrations of placental molybdenum in pregnancies complicated by foetal growth restriction, postdate delivery, and stillbirth. © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
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    Probing the effect of Mg doping on triclinic Na2Mn3O7 transition metal oxide as cathode material for sodium-ion batteries
    (Elsevier, 2021-02-20) Siriwardena, DP; Fernando, JFS; Wang, T; Firestein, KL; Zhang, C; Brand, HEA; Jones, MWM; Kewish, CM; Berntsen, P; Jenkins, T; Lewis, CEM; von Treifeldt, JE; Dubal, DP; Golberg, DV
    Triclinic Na2Mn3O7 has been identified as a promising material for high-capacity sodium-ion batteries. However, the knowledge on the effect of doping of metal ions and structural transformations of Na2Mn3O7 during dis(charge) is limited. Integration of alkali metal-ions, specially Mg2+ can enhance the electrochemical properties in transition metal oxides. Herein, a series of Mg2+ doped triclinic Na2Mn3O7 cathode materials was explored for the first time. Electrochemical analysis revealed that Mg2+ improves specific capacities, and rate capabilities. Ex situ X-ray diffraction (XRD) and Galvanostatic charge discharge cycling (GCD) showed that the triclinic phase reversibly converts into two monoclinic phases at high Na+ insertion levels. Na+ extraction at high potentials is supported by another biphasic region which converts to a major triclinic phase at the end of the charge. GCD, cyclic voltammetry (CV) and ex situ X-ray absorption spectroscopy (XAS) documented that the capacity mainly evolved through a Mn4+/3+ redox couple and a reversible O2-/n− redox reaction. CV and Galvanostatic intermittent titration techniques (GITT) showed that Mg2+ reduces the Na+-vacancy ordering and improves the Na+ diffusion. The 2 mol.% Mg-doped material exhibited a high specific capacity of 143 mAh/g after 30 cycles and a rate capability of 93 mAh/g (at 500 mA/g). GCD analysis demonstrated that O2-/n− redox is remarkably stable up to at least 90 cycles. Full cells made using the 0.5 mol.% Mg-doped material displayed a promising discharge specific capacity of 80 mAh/g. The effects of cation doping into the complex crystal structures, phase transformations during Na+ de(intercalation) and the importance of O2-/n− redox for achieving high capacities were uncovered. The findings of this work will guide the design of novel cathode materials for sodium-ion batteries. ©2021 Elsevier Ltd.
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    Simultaneously localising biometals within the high resolution ultrastructure of whole C. elegans
    (Australian Microscopy and Microanalysis Society, 2016-02-04) Jones, MWM; McColl, G; van Riessen, GA; Phillips, NW; Vine, D; Abbey, B; de Jonge, MD
    Ptychography is a coherent diffraction imaging method where multiple overlapping diffraction frames are combined, providing high resolution images of the electron density of extended objects. Recently, X-ray ptychography has seen many efficiency improvements that allow large areas to be imaged rapidly, making simultaneous X-ray ptychography and fluorescence microscopy experimentally viable. Here we use simultaneous X-ray fluorescence microscopy and ptychography to image entire C. elegans, with sub-micron and sub 100 nm elemental and ultrastructure resolutions respectively. Rapid data collection allowed the entire 1 mm long animal to be imaged in only a few hours. With the information from both techniques, the elemental maps can be viewed in the context of the high resolution ultrastructure, allowing further insights into the localisation of the fluorescent signal.
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    A technique for preparing undecalcified osteochondral fresh frozen sections for elemental mapping and understanding disease etiology
    (Springer Nature, 2022-07-09) Fan, XW; Lee, KM; Jones, MWM; Howard, DL; Crawford, R; Prasadam, I
    The anatomy of the osteochondral junction is complex because several tissue components exist as a unit, including uncalcified cartilage (with superficial, middle, and deep layers), calcified cartilage, and subchondral bone. Furthermore, it is difficult to study because this region is made up of a variety of cell types and extracellular matrix compositions. Using X-ray fluorescence microscopy, we present a protocol for simultaneous elemental detection on fresh frozen samples. We transferred the osteochondral sample using a tape-assisted system and successfully tested it in synchrotron X-ray fluorescence. This protocol elucidates the distinct distribution of elements at the human knee’s osteochondral junction, making it a useful tool for analyzing the co-distribution of various elements in both healthy and diseased states. © The Author(s) 2022 - Open Access under a Creative Commons Attribution 4.0 International License,