Open Access

Show Abstract ▼

Abstract: High-resolution nano-focus X-ray fluorescence microscopy using hard X-rays at the European Synchrotron Radiation Facility (ESRF) IDB16 beamline detected endogenous barium, bromine, calcium, chlorine, copper, iron, manganese, potassium, phosphorus, rubidium, sulphur, selenium, strontium and zinc, at tissue, cellular and subcellular level in the outer retinal complex of light adapted, 3-week-old, male C57BL6 mice. Fresh snap-frozen (20 μm) cryosections dried at room temperature were scanned at 1 μm, 300 nm and 50 nm spatial resolution by incident X-ray photons from the synchrotron beam. Analysis of 2D maps and 3D surface plots by PyMCA and ImageJ revealed elevated zinc concentrations in the choriocapillaris (CC) (mean 45, range 28–77 ppm), retinal pigment epithelium (RPE) layer (mean 47, range 20–76 ppm), photoreceptor inner segments (RIS) ellipsoid zone, outer limiting membrane (OLM) (mean 32, range < 1–44 ppm) and outer nuclear layer (ONL) in between photoreceptor cell bodies. Mūller cells processes in ONL and their interdigitations in RIS ellipsoid zone seem to contain zinc in the cell membrane. Iron was found at elevated amounts in RIS myoid zone (mean 38, range 14–68 ppm), RPE layer (52, range 24–143 ppm), and choroid (60, range 36–172 ppm). Copper was also detected in the CC (4.3, range 1.9–9.7 ppm), RPE layer (4.5, range 1.6–20.8 ppm), and RIS myoid zone (4.9, range 1.25–10.2 ppm). Calcium was found with granular/punctate distribution in OLM (159, range 49–962 ppm), RIS myoid zone (245, range 36-1370 ppm), RPE layer (1134, range 257–2503 ppm), and CC (1101, range 323–2090 ppm). The metalloid selenium was present in the CC (1.8, range < 1-4.7 ppm] and across the RPE (basal, central, apical) (2.4, range < 1-8.5 ppm). High resolution maps of the interface photoreceptor outer segments (ROS) and the RPE apical side revealed selenium-rich spherical structures (appr. 1 μm diameter) (mean 5.6, range 2.2–8.1 ppm), associated with calcium (mean 1057, range 619–1755 ppm), phosphorus (9924, range 6118–15058 ppm), and manganese (0.7, < 1–24 ppm), surrounded by a zinc-containing layer. This study presents the first nanoprobe X-ray fluorescence microscopy image analysis of adult mouse light adapted outer retinal complex from the whole tissue to subcellular structures. The high spatial resolution (location) and high sensitivity (metal quantity) findings, together with the information on biometals available in the literature, allowed us to propose a schematic model of possible selenium biological processes and their role in physiological activities in the outer retinal complex. We hypothesise there is a dedicated selenium-rich spherical structure with the ability to cross RPE cell membranes (i.e. the outer blood retinal barrier) and with potential roles in certain biological function(s) (e.g. ROS phagocytosis by RPE cell microvilli, trans-RPE transport).

Open Access

Show Abstract ▼

Abstract: As the demand for copper increases, processing increasingly low-grade ore has become a critical challenge. Most of these ores are dominated by aluminosilicate gangue minerals, among which Fe-bearing phyllosilicates are the most reactive. The effect of Fe-bearing minerals on the acid leaching of chalcopyrite, the most common primary Cu ore mineral was investigated by comparing mixtures of chalcopyrite with (i) chamosite, (ii) berthierine-chamosite, and (iii) pyrite. The lixiviant consisted of solutions with 0.1 m Fe2(SO4)3 + 0.3 m H2SO4, and the experiments were conducted in an orbital shaking water bath at 50°C for 43 days. The solution pH increased and Eh decreased for all systems, resulting in conditions that became less optimal for Cu recovery. Scanning electron microscope imaging highlighted the porous nature and variable elemental composition of the (partially) dissolved phyllosilicate minerals/amorphous-silica-residue after leaching. Micro X-ray Absorption Near Edge Structure (μXANES) measurements revealed that sulfur exists in multiple oxidation states both within the silicate gangue and around chalcopyrite, emphasising how the formation of an amorphous-silica-residue increased the complexity of the system. This complexity is related to the fact that (partial) dissolution of phyllosilicate gangue minerals during acid leaching results in the release of ions that change the solution chemistry; and form an amorphous-silica-residue, that contains numerous pores. These pores can act as local micro-reactors with non-equilibrium conditions and promote a heterogenous chemical composition. Subsequent mineral surface-fluid interactions in (partially) dissolved phyllosilicate/amorphous-silica-residue pores can vary, depending on the local chemical composition, making the leaching behaviour of chalcopyrite highly dependent on local conditions and on the mineralogical composition of the ores.

Open Access

Show Abstract ▼

Abstract: Despite being pivotal to the habitability of our planet, the process by which Earth gained its present-day hydrogen budget is unclear. Due to their isotopic similarity to terrestrial rocks across a range of elements, the meteorite group that is thought to best represent Earth's building blocks is the enstatite chondrites (ECs). Because of ECs' nominally anhydrous mineralogy, these building blocks have long been presumed to have supplied negligible hydrogen to the proto-Earth. However, recent bulk compositional measurements suggest that ECs may unexpectedly contain enough hydrogen to readily explain Earth's present-day water abundance. Together, these contradictory findings mean the contribution of ECs to Earth's hydrogen budget is currently unclear. As such, it is uncertain whether appreciable hydrogen is a systematic outcome of Earth's formation. Here, we explore the amount of hydrogen in ECs as well as the phase that may carry this element using sulfur X-ray absorption near edge structure (S-XANES) spectroscopy. We find that hydrogen bonded to sulfur is prevalent throughout the meteorite, with fine matrix containing on average almost 10 times more Hsingle bondS than chondrule mesostasis. Moreover, the concentration of the Hsingle bondS bond is linked to the abundance of micrometre-scale pyrrhotite (Fe1-xS, 0 < x < 0.125). This sulfide can sacrificially catalyse a reaction with H2 from the disk at high temperatures to create H2S, which could be dissolved in adjoining molten silicate-rich material. Upon rapid cooling, this assemblage would form pyrrhotite encased in submicron silicate-rich glass that carries trapped H2S. These findings indicate that hydrogen is present in ECs in higher concentrations than previously considered and could suggest that this element may have a systematic, rather than stochastic, origin on our planet.

Open Access

Show Abstract ▼

Abstract: Structural batteries utilise the bifunctionality of carbon fibres to act as a load-bearing structure, but also as a conductive current collector for a battery electrode. Lithium-ion transport during the cycling of structural battery cathodes coated with different morphologies is investigated using Iron X-Ray Absorption Near Edge Spectroscopy (Fe XANES) and correlated to electrochemical performance. Two contrasting morphologies were produced using slurry coating and electrophoretic deposition (EPD) of lithium-iron phosphate (LFP) onto continuous carbon fibres. The ability to study the different structural battery cathode morphologies operando allows for a comparative analysis of their impact on cycling performance. The EPD-coated fibres exhibited a more homogeneous, thinner coating around the fibre compared to the thick, one-sided coating produced using slurry coating. Despite a lower initial capacity and 30 % lithium re-intercalation loss in the first cycle, EPD-coated fibres exhibited more stable capacity retention over time compared to slurry-coated counterparts. Electrochemical Impedance Spectroscopy (EIS) revealed initially high ionic resistance for the EPD-coated fibres, but a larger increase in resistance in the slurry coated electrodes over multiple cycles. This study demonstrated an innovative and novel method of analysing in greater detail, the cycling ability of the coated cathode material on carbon fibres using synchrotron radiation.

Show Abstract ▼

Abstract: Prostate cancer (PCa) is the most diagnosed cancer in Canadian men, accounting for 20% of all new cancer cases in 2023[1]. With such high incidence, it is important that diagnostic tools advance for adequate treatment of the disease. Contrast agents (CA) are administered in magnetic resonance imaging (MRI) clinical exams to enhance image contrast between adjacent structures and tissues. The efficacy of a CA is determined by the distribution and concentration of the agent throughout organs of interest and in the extracellular space of all tissues. Micro-synchrotron radiation x-ray fluorescence (μ-SRXRF) is a non-destructive measurement technique that uses a tunable photon beam focused to the micron scale. In this work, μ-SRXRF was used to examine and characterize the co-localization of a gadolinium-based zinc-sensitive agent (GdL2) currently under development for detection of PCa by MRI. Prostate tissue samples were collected from control mice and transgenic adenocarcinoma of the mouse prostate (TRAMP) mice, an established prostate cancer model [2], after an MRI exam that included injection of GdL2. The samples were raster scanned to investigate trends in Gd, from the CA, and Zn, a biomarker for PCa diagnoses. Elements such as Cu, Fe, S, P, and Ca were also investigated. Significant Zn and Gd co-localization was observed in both healthy and malignant mouse tissues. In addition, a marked decrease in Zn was found in the lateral lobe of the prostate obtained from mice with PCa. We demonstrate here that μ-SRXRF is a useful tool for monitoring the distribution of several elements including Zn and Gd in animal models of cancer. The optimized procedures for tissue preparation, processing, data collection, and analysis will be described.