I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[15475, 15215, 12700]
Open Access
Abstract: The agricultural soils of West Limerick, Ireland, contain very localised, extremely high natural Se concentrations that reach levels that are very toxic to grazing livestock. The Carboniferous shales that formed in anoxic deep-water marine environments are the source of the selenium, which, along with the other redox-sensitive elements of molybdenum, uranium, arsenic and vanadium, were mobilised and reprecipitated in post-glacial anoxic marshes. The result has been a history of selenosis and molybdenosis in livestock in this important dairy province. Soils collected at 10–20 cm from five different agricultural sites were analysed, and all yielded concentrations greatly in excess of the safe Se limits of 3–10 mg kg−1; the highest value recorded was 1265.8 mg kg−1 Se. The highest recorded value for Mo in these soils was 1627.5 mg kg−1, and for U, 658.8 mg kg−1. There was a positive correlation between Se, Mo U and organic matter in the soils. Analysis of non-accumulator pasture grasses (Lolium perenne (perennial ryegrass), Festuca arundinacea (tall fescue), Dactylis glomerata (cocksfoot) and Phleum pretense (timothy grass)) revealed the shoot/leaf to contain up to 78.05 mg kg−1 Se while Trifolium repens (white clover) leaves contained 296.15 mg kg−1 Se. An in situ growing experiment using the Se accumulator species Brassica oleracea revealed 971.2 mg kg−1 Se in the leaves of premier kale, which also contained 1000.4 mg kg−1 Mo. Translocation factors (TFs) were generally higher for Mo than Se across all plant species. Combined X-ray absorption near edge spectroscopy (XANES) with micro-X-ray fluorescence (μ-XRF) showed the Se was present in the soil predominantly as the reduced immobile phase, elemental Se (Se0), but also as bioavailable organoselenium species, mainly selenomethionine (SeMet). SeMet was also the main species identified within both the Se non-accumulator and Se accumulator plants. The Se soil–plant system in West Limerick is dominated by SeMet, and uptake into the cattle pasture results in selenosis in the grazing dairy herds. The hyperaccumulating Brassica oleracea species could be used to extract both the Se and Mo to reduce the toxicity of the blighted fields.
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Mar 2023
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[15947]
Open Access
Abstract: The alteration of olivine-rich rocks to serpentine minerals, (hydr)oxides, and aqueous hydrogen through serpentinization is long thought to have influenced the distribution of habitable environments on early Mars and the evolution of the early Martian hydrosphere and atmosphere. Nevertheless, the planetary importance of Martian serpentinization has remained a matter of debate. To constrain the process and products of Martian serpentinization, we studied serpentinized iron-rich olivines from the 1.1-billion-year Duluth Complex. These data indicate that serpentinized iron-rich olivine would have been accompanied by a fivefold increase in hydrogen production relative to serpentinized terrestrial mantle peridotites. In contrast to previous expectations, this style of serpentinization yields hisingerite as the dominant iron serpentine mineral at comparatively low temperature and pH, consistent with meteorite mineralogy and in situ rover data. The widespread occurrence of oxidized iron-bearing phyllosilicates in highly magnetized regions of the Martian crust supports the hypothesis that serpentinization was more pervasive on early Mars than currently estimated.
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Feb 2023
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E01-JEM ARM 200CF
E02-JEM ARM 300CF
I14-Hard X-ray Nanoprobe
I18-Microfocus Spectroscopy
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Open Access
Abstract: Phyllosilicate minerals in the carbonaceous chondrites provide insights into processes in primitive parent bodies of the early Solar System. It is widely agreed that the CM- and CI-type carbonaceous chondrites underwent aqueous alteration on their parent bodies, resulting in phyllosilicate-rich matrices, where the dominant mineral phase is serpentine. There are many previous studies investigating phyllosilicate structure in carbonaceous chondrites, however, the presence of sulfur in these minerals and its effect on crystal lattice structure has not been studied in detail. We are investigating how the presence of sulfur (up to ≃9-10 wt% SO3) in serpentine phyllosilicate regions effects basal lattice spacing measurements of serpentine-like minerals in CM- and CI-type chondritic and related asteroidal material.
Four specimens are being studied for this work: Winchcombe and Aguas Zarcas (CM-type), and Ryugu samples (A0058-C2001-08, A0104-00200502 and A0104-01700602) from Hayabusa2 and Ivuna (CI-type). All samples are TEM wafers. We have used a multi-technique approach to study the samples, with the E01 JEOL ARM200CF and E02 JEOL ARM300CF electron microscopes at the ePSIC facility at Diamond Light Source in Harwell, UK. EDS compositional data has been collected using the E01 microscope, whilst HRTEM and HAADF imaging data has been collected at E02. At E02 we are also applying a new 4D-STEM nano-diffraction technique in order to collect lattice spacing data to correlate with our other HRTEM results. Fe-K XANES analyses on Winchcombe and Ryugu have been carried out using the I18 microprobe and I14 hard x-ray nanoprobe respectively, also at Diamond Light Source, to constrain Fe3+/ΣFe. By combining these techniques we aim to better understand the physical and chemical structure of serpentine-like minerals in carbonaceous chondrites.
Initial analyses have shown that sulfur presence in carbonaceous chondrite phyllosilicates reduces the basal lattice spacings of serpentine-like minerals. In these sulfur-bearing regions, we have been finding lattice spacings in the range ~0.60-0.74nm for the CM-type chondrites. For the CI-type, these range between ~0.65-0.76nm. Differences in the reduced lattice spacing ranges are likely related to the redox state of the sulfur. In Ryugu and other carbonaceous chondrites the sulfur appears reduced; its content in serpentine is low and we see FeS grains. Comparatively, in Winchcombe (and others) more of the sulfur seems to be in the serpentine structure.
We can conclude that in serpentine-like minerals, the presence of sulfur appears to reduce basal lattice spacing values compared to the expected d-spacing value of 0.70nm for serpentine. Possible reasons for this include further investigations into the valency of the sulfur ions, the bonding environment within serpentine layers, and the location of sulfur in either the octa- or tetrahedral lattice sites.
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Feb 2023
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[28784]
Open Access
Abstract: The local bonding environment of chlorine in silicate melts has a profound influence over the thermodynamic properties and structure of a melt, affecting the viscosity, rheology, and volatile degassing potential. To constrain the bonding environment of Cl in natural silicate melts, we have determined Cl K-edge X-ray absorption fine structure (XAFS) spectra for 44 experimentally produced silicate glasses in both the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions. In the pre-edge region, the presence of a pre-edge peak indicates covalent bonding of chlorine with silicon. Addition of divalent cations suppresses this pre-edge feature, and its centroid shifts to higher energy, indicating a change to increasingly more ionic bonding. In the XANES region the main absorption edge energy, E0, and the energy of maximum intensity, EMax, are also compositionally dependent. SiO2- rich glasses have relatively low values of E0 and EMax while the addition of 2+ ions increases both to values close to those found in the end-member chlorides CaCl2, MgCl2, and FeCl2. In two Na-rich glasses, E0 and EMax are close to corresponding energies in NaCl. It appears, therefore that bonding in the glasses is closely related to that found in the simple chlorides. This may be due to clustering which generates Casingle bondCl, Mgsingle bondCl, Fesingle bondCl and Nasingle bondCl linkages either in the melts themselves or in the glasses due to rearrangements during quenching.
The EXAFS parts of the glass spectra confirm the conclusions derived from the XANES region. These show that, as expected from the XANES region, addition of Ca and Fe2+ leads to R-space peaks which are closely related to those found in anhydrous CaCl2 and FeCl2 respectively.
In order to determine if the spectra depend on pressure, temperature or chlorine fugacity of synthesis, 9 experiments were conducted using a single starting composition (Fe-free haplobasalt, An50Di28Fo22) across a range of temperatures (1300–1400 °C), pressures (5–20 kbar), chlorine fugacities (f(Cl2)) (1.38E−03 to 1.66E−06), and water contents (expected 0–8 wt% H2O). The results show that there is almost no change in the spectra across the XANES and EXAFS regions, indicating either that chlorine bonding is independent of the intensive parameters of the experiment or that all melts quench to glasses with the same local structure around the Cl atoms.
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Dec 2022
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I14-Hard X-ray Nanoprobe
I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[12477, 29965]
Open Access
Abstract: Synchrotron radiation (SR) techniques, which use high-energy photon beams to create high-resolution images and spectra of a sample, are valuable analytical methods that have long benefited physical, geological, and biochemical research. Recent developments in synchrotron infrastructure have allowed SR techniques to become a more accessible resource for studying ecological and evolutionary phenomena at the micro- or nanoscale. Here we provide a synthesis to SR techniques, how they compare with other analytical techniques, how they have been used, and then discuss how this technology has significant potential for future applications within ecology and evolution research. A literature review demonstrates the growing use of SR techniques within environmental and ecological research communities, alongside the variety of organisms and target elements that have been prioritized since 2000. Clear gaps still exist within the imaging of lighter, biologically relevant elements (e.g., C, N, and P) for assessing their cycling within organisms, and also in the study of a wider range of microbial, vertebrate, and invertebrate species. While different organism types and target elements may require different sample preparation strategies, the selection of an appropriate elemental fixation method (chemical or cryogenic), embedding material, sample thickness, and mounting material is particularly important. We demonstrate the opportunities that SR techniques present to those in the fields of environmental biology, ecology, and evolutionary science who may be unfamiliar, while demystifying the caveats and sample preparation considerations that must be addressed to acquire high-quality data. While these techniques are currently mainly employed within the context of environmental pollution and ecotoxicology studies, we argue that elemental imaging, X-ray microscopy and spectroscopic analysis have a huge, largely untapped potential within agri-ecology, paleoclimatology, and comparative and functional morphology studies.
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Dec 2022
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[23705]
Abstract: Background: Contrast agents (CA) are administered in magnetic resonance imaging (MRI) clinical exams to measure tissue perfusion, enhance image contrast between adjacent tissues, or provide additional biochemical information in molecular MRI. The efficacy of a CA is determined by the tissue distribution of the agent and its concentration in the extracellular space of all tissues. Methods: In this work, micro-synchrotron radiation x-ray fluorescence (µ-SRXRF) was used to examine and characterize a gadolinium-based zinc-sensitive agent (GdL2) currently under development for detection of prostate cancer (PCa) by MRI. Prostate tissue samples were collected from control mice and mice with known PCa after an MRI exam that included injection of GdL2. The samples were raster scanned to investigate trends in Zn, Gd, Cu, Fe, S, P, and Ca. Results: Significant Zn and Gd co-localization was observed in both healthy and malignant tissues. In addition, a marked decrease in Zn was found in the lateral lobe of the prostate obtained from mice with PCa. Conclusion: 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 are described.
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Dec 2022
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I18-Microfocus Spectroscopy
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Abstract: In this work, x-ray and optical techniques were utilized to analyze tissue for two main applications in cancer: intraoperative breast cancer margin assessment and contrast agent development for prostate cancer magnetic resonance imaging (MRI). A clinically compatible combined time-resolved fluorescence and diffuse reflectance (TRF-DR) spectroscopy system was used to measure breast tissue from 80 patients with invasive ductal carcinoma (IDC). A procedure was developed to compare extracted optical parameters with histological analysis. Trends in optical parameters between breast tumor, adipose, and fibroglandular tissue were investigated. Optical parameters that showed statistically significant differences between tissue groups were used in multivariate analysis and tissue modelling. Tissue classification using the combined system resulted in tumor detection sensitivity and specificity of 83.9% and 96.2%, respectively. Further work studying more fibroglandular tissue and tissue of mixed composition would develop this system for intraoperative use for tumor margin detection. In addition, micro-synchrotron radiation x-ray fluorescence (μ-SRXRF) was used to determine the efficacy of a novel gadolinium-based contrast agent for zinc-targeting in prostate cancer imaging. Trends in elements of interest such as Gd, Zn, Fe, Cu, and S between mice with prostate cancer, castrate-resistant prostate cancer, and normal mice were observed. Raster scans were collected of large regions of the prostate as well as within the lateral lobe specifically. Significant Zn and Gd co-localization was observed in both healthy and malignant tissues. Also, a marked decrease in Zn was found in the lateral lobe of the prostate obtained from mice with prostate cancer. The sample preparation and processing procedure outlined in this work provide a feasible and effective method of assessing the efficacy of MRI contrast agents in vivo. With the ability to use a beam as small as 5μm × 5μm, this optimized technique also lends itself to the investigation of other elements and contrast agents in biological tissue.
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Dec 2022
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I08-Scanning X-ray Microscopy beamline (SXM)
I18-Microfocus Spectroscopy
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Agnieszka
Dybowska
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Paul
Schofield
,
Laura
Newsome
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Richard
Herrington
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Julian F. W.
Mosselmans
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Burkhard
Kaulich
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Majid
Kazemian
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Tohru
Araki
,
Thomas J.
Skiggs
,
Jens
Kruger
,
Anne
Oxley
,
Rachel L.
Norman
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Jonathan R.
Lloyd
Diamond Proposal Number(s):
[14882, 14908, 17882]
Open Access
Abstract: The Piauí laterite (NE Brazil) was initially evaluated for Ni but also contains economic concentrations of Co. Our investigations aimed to characterise the Co enrichment within the deposit; by understanding the mineralogy we can better design mineral processing to target Co recovery. The laterite is heterogeneous on the mineralogical and lithological scale differing from the classic schematic profiles of nickel laterites, and while there is a clear transition from saprolite to more ferruginous units, the deposit also contains lateral and vertical variations that are associated with both the original intrusive complex and also the nature of fluid flow, redox cycling and fluctuating groundwater tables. The deposit is well described by the following six mineralogical and geochemical units: SAPFE, a clay bearing ferruginous saprolite; SAPSILFE, a silica dominated ferruginous saprolite; SAPMG, a green magnesium rich chlorite dominated saprolite; SAPAL, a white-green high aluminium, low magnesium saprolite; saprock, a serpentine and chlorite dominated saprolite and the serpentinite protolith. Not all of these units are ‘ore bearing’. Ni is concentrated in a range of nickeliferous phyllosilicates (0.1–25 wt%) including serpentines, talc and pimelite, goethite (up to 9 wt%), magnetite (2.8–14 wt%) and Mn oxy-hydroxides (0.35–19 wt%). Lower levels of Ni are present in ilmenites, chromites, chlorite and distinct small horizons of nickeliferous silica (up to 3 wt% Ni). With respect to Co, the only significant chemical correlation is with Mn, and Mn oxy-hydroxides contain up to 14 wt% Co. Cobalt is only present in goethite when Mn is also present, and these goethite grains contain an average of 0.19 wt% Co (up to a maximum of 0.65 wt%). The other main Co bearing minerals are magnetite (0.41–1.89 wt%), chlorite (up to 0.45 wt%) and ilmenite (up to 0.35 wt%). Chemically there are three types of Mn oxy-hydroxide, asbolane, asbolane-lithiophorite intermediates and romanechite. Spatially resolved X-ray absorption spectroscopy analysis suggests that the Co is present primarily as octahedrally bound Co3+ substituted directly into the MnO6 layers of the asbolane-lithiophorite intermediates. However significant levels of Co2+ are evident within the asbolane-lithiophorite intermediates, structurally bound along with Ni in the interlayer between successive MnO6 layers. The laterite microbial community contains prokaryotes and few fungi, with the highest abundance and diversity closest to ground level. Microorganisms capable of metal redox cycling were identified to be present, but microcosm experiments of different horizons within the deposit demonstrated that stimulated biogeochemical cycling did not contribute to Co mobilisation. Correlations between Co and Mn are likely to be a relic of parent rock weathering rather than due to biogeochemical processes; a conclusion that agrees well with the mineralogical associations.
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Oct 2022
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[31047, 26697]
Open Access
Abstract: Semiconductors in their optical-fiber forms are desirable. Single-crystal organometallic halide perovskites have attractive optoelectronic properties and therefore are suitable fiber-optic platforms. However, single-crystal organometallic perovskite optical fibers have not been reported before due to the challenge of one-directional single-crystal growth in solution. Here, we report a solution-processed approach to continuously grow single-crystal organometallic perovskite optical fibers with controllable diameters and lengths. For single-crystal MAPbBr3 (MA = CH3NH3+) perovskite optical fiber made using our method, it demonstrates low transmission losses (<0.7 dB/cm), mechanical flexibilities (a bending radius down to 3.5 mm), and mechanical deformation–tunable photoluminescence in organometallic perovskites. Moreover, the light confinement provided by our organometallic perovskite optical fibers leads to three-photon absorption (3PA), in contrast with 2PA in bulk single crystals under the same experimental conditions. The single-crystal organometallic perovskite optical fibers have the potential in future optoelectronic applications.
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Sep 2022
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[25932]
Open Access
Abstract: The doping of functionalized graphene oxide (GO) in the membranes becomes a promising method for improving the performance of high-temperature proton exchange membrane fuel cells (HT-PEMFC). Phosphonated graphene oxide (PGO) with a P/O ratio of 8.5% was quickly synthesised by one-step electrochemical exfoliation based on a 3D printed reactor and natural graphite flakes. Compared with the GO prepared by the two-step electrochemical exfoliation method, the PGO synthesized by the one-step electrochemical exfoliation can better improve the performance of the membrane-electrode-assembly (MEA) based on the Polybenzimidazole (PBI) membrane in the HT-PEMFC. The doping of 1.5 wt% GO synthesised by electrochemical exfoliation with the 2-step method or reactor method in PBI increased the peak power density by 17.4% or 35.4% compared to MEA based on pure PBI membrane at 150 ℃, respectively. In addition, the doping of PGO in PBI improves its durability under accelerated stress test (AST).
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Sep 2022
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