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Context Hyperaccumulator plants are of considerable interest for their extreme physiology. Stackhousia tryonii is a nickel (Ni) hyperaccumulator plant endemic to ultramafic outcrops in Queensland (Australia) capable of attaining up to 41 300 μg g−1 foliar Ni. Aims This study sought to elucidate the distribution of Ni in S. tryonii by using synchrotron X-ray fluorescence micro-computed tomography (XFM-CT), complemented with elemental maps acquired from physically sectioned plant organs. Its Ni-enriched cylindrical photosynthetic stems make them particularly well suited samples for synchrotron XFM-CT. Methods XFM-CT enables ‘virtual sectioning’ of a sample, avoiding artefacts arising from physical sample preparation. The method can be used on fresh samples that are frozen during the analysis, which preserves ‘life-like’ conditions by limiting radiation damage. It also prevents/minimises other artefacts. Key results The results showed that Ni is mainly concentrated in the apoplastic space surrounding epidermal cells, and in some epidermal cell vacuoles. This finding is significant because this ‘free’ solute Ni is likely to be lost during physical sectioning. Conclusions and implications This case study has highlighted the utility of the XFM-CT approach for visualising metals within intact plant organs, which may be used across the plant sciences.

Lead (Pb) is a well-known neurotoxicant and environmental hazard. Recent experimental evidence has linked Pb exposure with neurological deterioration leading to neurodegenerative diseases, such as Alzheimer’s disease. To understand brain regional distribution of Pb and its interaction with other metal ions, we used synchrotron micro-x-ray fluorescence technique (μ-XRF) to map the metal distribution pattern and to quantify metal concentrations in mouse brains. Lead-exposed mice received oral gavage of Pb acetate once daily for 4 weeks; the control mice received sodium acetate. Brain tissues were cut into slices and subjected for analysis. Synchrotron μ-XRF scans were run on the PETRA III P06 beamline (DESY). Coarse scans of the entire brain were performed to locate the cortex and hippocampus, after which scans with higher resolution were run in these areas. The results showed that: a) the total Pb intensity in Pb-exposed brain slices was significantly higher than in control brain; b) Pb typically deposited in localized particles of

Inhomogeneities and defects often limit the overall performance of thin-film solar cells. Therefore, sophisticated microscopy approaches are sought to characterize performance and defects at the nanoscale. Here, we demonstrate, for the first time, the simultaneous assessment of composition, structure, and performance in four-fold multi-modality. Using scanning X-ray microscopy of a Cu(In,Ga)Se2 (CIGS) solar cell, we measured the elemental distribution of the key absorber elements, the electrical and optical response, and the phase shift of the coherent X-rays with nanoscale resolution. We found structural features in the absorber layer—interpreted as voids—that correlate with poor electrical performance and point towards defects that limit the overall solar cell efficiency.

Materials 14(5), 1189 (2021). doi:10.3390/ma14051189, Published by MDPI, Basel

Histological analysis of biological structures in the avian beak is performed by means of large-scalehigh-resolutionmicro-X-ray fluorescence analysis using a Maia detector system. Element maps of S, K, Ca, Fe and Zn of square millimeter sizes show distinct cellular and subcellular tissue structures in semi-thin sections with a resolution at the (sub-)micrometer scale. Non-destructive qualitative and quantitative evaluation of the respective trace elements can be performed on the tissue samples. The elemental maps are compared with conventional differential histological stainings of parallel sections. This method is discussed as a pre-examination tool for subsequent analysis of selected structural sites by diffractive and spectroscopic X-ray nanoprobe techniques and, after additional ultrasectioning, also by transmission electron microscopy. Copyright © 2017 John Wiley & Sons, Ltd.

Plant and soil 457(1-2), 293 - 320 (2020). doi:10.1007/s11104-020-04714-x, AimsThis study aimed to establish elemental profiles and to spatially resolve the elemental distribution in five New Caledonian woody Ni hyperaccumulator plant species (Geissois pruinosa var. pruinosa, Homalium francii, Hybanthus austrocaledonicus, Psychotria gabriellae, and Pycnandra acuminata) originating from the Cunoniaceae, Salicaceae, Violaceae, Rubiaceae, and Sapotaceae families respectively.MethodsUsing synchrotron-based micro-X-ray Fluorescence (��XRF) imaging of different plant tissues, from the roots to the shoots and reproductive organs, this study aimed to clarify how distribution patterns of nickel, and other physiologically relevant elements, differ between these species.ResultsThe results show that the tissue-level and cellular-level distribution of nickel in P. gabriellae, H. austrocaledonicus, G. pruinosa var. pruinosa, and H. francii conform with the majority of studied Ni hyperaccumulator plant species globally, including (temperate) herbaceous species, with localization mainly in epidermal cells and phloem bundles. However, P. acuminata has nickel-rich laticifers, which constitute an independent network of cells that is parallel to the vascular bundles and are the main sink for nickel.ConclusionsSynchrotron-based micro-X-ray Fluorescence (��XRF) is a powerful method for investigating how metal hyperaccumulation influences acquisition and spatial distribution of a wide range of elements. This non-invasive method enables investigation into the in vivo distribution of multiple elements and the structure and organisation of cells (e.g. laticifers)., Published by Springer Science + Business Media B.V, Dordrecht [u.a.]

Plant and soil 455, 289 ��� 303 (2020). doi:10.1007/s11104-020-04629-7, $Aims$Knowledge on the ecophysiology of cobalt hyperaccumulator species is limited. The nickel hyperaccumulator Rinorea cf. bengalensis from Borneo can accumulate high concentrations of cobalt in nature. This study investigates the cobalt accumulation potential of Rinorea cf. bengalensis in relation to nickel concentrations in soils and the subsequent tissue and cellular-level distributions of cobalt, nickel and major cations.$Methods$Seedlings of Rinorea cf. bengalensis were grown in mixed treatments on ultramafic soil containing a high concentration of available nickel. Cobalt and nickel salts were then added to the soil to study their interactions. The tissue and cellular-level distributions of cobalt, calcium, nickel, and potassium were investigated using synchrotron-based X-ray fluorescence microscopy.$Results$The maximum foliar cobalt concentration reached 1200 ��g g$^{���1}$. Accumulation of cobalt competed with nickel accumulation although nickel seems to stimulate cobalt phloem translocation. Plants suffered toxicity in the treatment with the highest soil cobalt concentration. Cobalt and nickel have contrasting distribution patterns in the leaves of Rinorea cf. bengalensis, with cobalt mainly excreted on the surface of the leaves, whereas nickel is localised in foliar epidermal cells.$Conclusions$Rinorea cf. bengalensis can accumulate high concentrations of cobalt, but is intrinsically more tolerant to nickel. It does not rely on a similar sequestration mechanism for both metals, which could explain the lesser tolerance for cobalt. Nickel appears to be essential for the plant to tolerate high cobalt concentrations. Further studies intending to develop agronomic practices are needed to determine the viability of Rinorea cf. bengalensis for nickel-cobalt agromining., Published by Springer Science + Business Media B.V, Dordrecht [u.a.]

The fern Dicranopteris linearis (Gleicheniaceae) from China is a hyperaccumulator of rare earth element (REE), but little is known about the ecophysiology of REE in this species. This study aimed to clarify tissue-level and organ-level distribution of REEs via synchrotron-based X-ray fluorescence microscopy (XFM). The results show that REEs (La + Ce) are mainly colocalized with Mn in the pinnae and pinnules, with the highest concentrations in necrotic lesions and lower concentrations in veins. In the cross sections of the pinnules, midveins, rachis, and stolons, La + Ce and Mn are enriched in the epidermis, vascular bundles, and pericycle (midvein). In these tissues, Mn is localized mainly in the cortex and mesophyll. We hypothesize that the movement of REEs in the transpiration flow in the veins is initially restricted in the veins by the pericycle between vascular bundle and cortex, while excess REEs are transported by evaporation and cocompartmentalized with Mn in the necrotic lesions and epidermis in an immobile form, possibly a Si-coprecipitate. The results presented here provide insights on how D. linearis regulates high concentrations of REEs in vivo, and this knowledge is useful for developing phytotechnological applications (such as REE agromining) using this fern in REE-contaminated sites in China.

ACS nano 13(11), 12949 - 12956 (2019). doi:10.1021/acsnano.9b05535, The biomineralization of bone remains apuzzle. During Haversian remodeling in the dense humancortical bone, osteoclasts excavate a tunnel that is then filledin by osteoblasts with layers of bone of varying fibrilorientations, resulting in a lamellar motif. Such bonerepresents an excellent possibility to increase our understandingof bone as a material as well as bonebiomineralization by studying spatio/temporal variations inthe biomineral across an osteon. To this end, fluorescencecomputed tomography and diffraction scattering computedtomography with sub-micrometer resolution is applied toobtain position resolved fluorescence spectra and diffractionpatterns in a 3D volume. The microstructural properties ofthe apatite biomineral are not homogeneous but depend critically on the time point at which it was laid down. Thisindicates that the nature of bone biomineral is highly dependent on the microenvironment during bone formation andremodeling., Published by Soc., Washington, DC

To date, compound refractive X-ray lenses made out of Beryllium (Be CRLs) have been seldom applied for full-field microscopy with high spatial resolution, which was probably due to residual aberrations of these optics. However, in combination with the recent development of made-to-measure phase plates, the typical spherical aberration of beryllium compound refractive lenses (Be CRLs) can now be completely removed. In this way, distortion-free images of a sample are obtained, which is especially important for tomographic applications. First full-field imaging experiments with aberration-corrected Be CRLs were carried out at beamline P06 at the synchrotron radiation X-ray source PETRA III (DESY Hamburg, Germany). In order to maximize the magnification of the X-ray microscope for full-field microscopy, the full length of the beamline combining the micro- and nanohutch was utilized, enabling a large sample-to-detector distance. In this contribution, we present first imaging results, demonstrating the potential of Be CRLs for direct high-resolution X-ray tomography.

Archives of oral biology 104, 90 - 102 (2019). doi:10.1016/j.archoralbio.2019.05.024, Objectives: Our first objective was to review the evidence describing the appearance and microstructure of theneonatal line in human deciduous teeth and to link this with known changes in neonatal physiology occurring atand around birth. A second objective was to explore ways to improve identification of the neonatal line bymapping the pre- and postnatal distribution of Ca, Sr and Zn in deciduous cuspal enamel and superimposingthese maps onto transmitted light micrographs that included a clear true section of the neonatal line.Materials and methods: We used synchrotron X-ray fluorescence to map elemental distributions in pre- andpostnatal enamel and dentine. Two deciduous canines and 5 deciduous molars were scanned with an X-ray beammonochromatised to 17.0 keV at either 10.0, 2.5 or 1.0 μm resolution and 10 ms integration time.Results: Calcium maps distinguished enamel and dentine but did not clearly demarcate tissues formed pre- orpostnatally. Strontium maps reflected presumed pre- and postnatal maternal serum levels and what are likely tobe diet-dependent regions of Sr enrichment or depletion. Prenatal Zn maps, particularly for dentine, mirrorelevated levels in the fetus and in colostrum during the first few days of life.Conclusions: The neonatal line, enamel dentine junction and surface enamel were all Zn-rich. Within the neonatalline Zn may be associated with increased crystallinity but also with caries resistance, both of which havebeen reported previously. Elemental mapping may improve the identification of ambiguous NNLs and so beuseful in forensic and archaeological studies., Published by Elsevier Science, Amsterdam [u.a.]

Parboiled rice is known to contain higher levels of nutrients than its non-parboiled counterpart. In order to study the diffusion of micronutrients into the starchy endosperm of the parboiled rice kernel, the parboiled paddy samples were prepared by combining different hydrothermal treatments (hydrated only, steamed-only, hydrated then steamed) employing two hydration temperatures (60 °C and 90 °C). The rice kernels were sectioned longitudinally into 90 μm thick sections after hydrothermal treatment, drying and milling. These rice kernels sections were analysed by Synchrotron X-Ray Fluorescence Microscopy (S-XFM) to determine the distribution of iron (Fe), manganese (Mn), potassium (K) and zinc (Zn). The S-XFM results showed that the bran and germ were rich in these minerals whereas the endosperm had a low concentration. Hydrothermal treatment of kernels increased the mineral diffusion into the endosperm from the bran layer and germ. The highest diffusion of Fe, Zn and Mn was observed in the sample treated with high temperature hydration for a longer time followed by steaming. However, K did not appear to diffuse into the endosperm as much as other the minerals.

Spectrochimica acta / B 157, 53 - 62 (2019). doi:10.1016/j.sab.2019.05.005, As many metals are essential for plants, excess or deficiency of them or alteration of their uptake, translocation, sequestration or physiological use can have severe consequences for plant growth and fitness. Therefore, investigating the distribution and speciation of metals in tissues is essential to understand plant physiology. We present a method based on non-destructive Synchrotron X-ray microtomography combined with microspectroscopy for studying metal distribution and speciation in plant tissues. By using the Maia detector system and the high flux of the undulator beam at the P06 beamline of the PETRA III synchrotron (at DESY), it was possible to record micro X-ray Absorption Near Edge Structure (μXANES) for every voxel of a tomogram. The metal coordination in regions of interest within the tissue samples could be determined by comparing the XANES with spectra of relevant reference compounds. Metal distribution and coordination were measured in shock frozen hydrated plant leaves in a cryostream, avoiding sample preparation artefacts like liquid cell content redistribution that occurs with other preparation methods, unequal distribution of stains in staining assays, sample degradation by beam damage and thawing, etc. A spatial resolution of 5 μm was selected, which is sufficient to resolve all leaf tissues (epidermis, palisade mesophyll, spongy mesophyll, veins), larger cells and biomineralization hotspots.As an application example, we studied the effect of infection with Turnip Yellow Mosaic Virus (TYMV) on the Zn distribution and the Zn speciation in duplicates of Noccaea ochroleucum. This non-accumulator plant grown with 100 μM Zn had enough metal to allow collecting significant spectroscopic data. We found that the TYMV infected samples formed biomineralization crystallites, showing strong spectroscopic similarity to Zn silicate., Published by Elsevier, Amsterdam [u.a.]

The fern Pteris vittata has been the subject of numerous studies because of its extreme arsenic hyperaccumulation characteristics. However, information on the arsenic chemical speciation and distribution across cell types within intact frozen-hydrated Pteris vittata fronds is necessary to better understand the arsenic biotransformation pathways in this unusual fern. While 2D X-ray absorption spectroscopy imaging studies show that different chemical forms of arsenic, As(III) and As(V), occur across the plant organs, depth-resolved information on arsenic distribution and chemical speciation in different cell types within tissues of Pteris vittata have not been reported. By using a combination of planar and confocal μ-X-ray fluorescence imaging and fluorescence computed μ-tomography, we reveal, in this study, the localization of arsenic in the endodermis and pericycle surrounding the vascular bundles in the rachis and the pinnules of the fern. Arsenic is also accumulated in the vascular bundles connecting into each sporangium, and in some mature sori. The use of 2D X-ray absorption near edge structure imaging allows for deciphering arsenic speciation across the tissues, revealing arsenate in the vascular bundles and arsenite in the endodermis and pericycle. This study demonstrates how different advanced synchrotron X-ray microscopy techniques can be complementary in revealing, at tissue and cellular levels, elemental distribution and chemical speciation in hyperaccumulator plants.

Hyperaccumulator plants present the ideal model system for studying the physiological regulation of the essential (and potentially toxic) transition elements nickel and zinc. This study used synchrotron X-ray Fluorescence Microscopy (XFM) elemental imaging and spatially resolved X-ray Absorption Spectroscopy (XAS) to elucidate elemental localization and chemical speciation of nickel and zinc in the hyperaccumulators Noccaea tymphaea and Bornmuellera emarginata (synonym Leptoplax emarginata). The results show that in the leaves of N. tymphaea nickel and zinc have contrasting localization, and whereas nickel is present in vacuoles of epidermal cells, zinc occurs mainly in the mesophyll cells. In the seeds Ni and Zn are similarly localized and strongly enriched in the cotyledons in N. tymphaea. Nickel is strongly enriched in the tip of the radicle of B. emarginata. Noccaea tymphaea has an Fe-rich provascular strand network in the cotyledons of the seed. The chemical speciation of Ni in the seeds of N. tymphaea is unequivocally associated with carboxylic acids, whereas Zn is present as the phytate complex. The spatially resolved spectroscopy did not reveal any spatial variation in chemical speciation of Ni and Zn within the N. tymphaea seed. The dissimilar ecophysiological behaviour of Ni and Zn in N. tymphaea and B. emarginata raises questions about the evolution of hyperaccumulation in these species.

Journal of cereal science 90, 102843 - (2019). doi:10.1016/j.jcs.2019.102843, Iron (Fe) and zinc (Zn) in wheat are mainly present as insoluble phytates in the aleurone cells. Phytate breakdown during steeping and germination of wheatenhances their bio-accessibility. However, the accompanying redistribution within the grain and changes in speciation are still unclear. We unravelled these changesusing a combination of wheat fractionation by pearling, X-ray fluorescence microscopy mapping and X-ray absorption near-edge structure imaging. A significantfraction of Zn and Fe migrates to radicles and coleoptiles during germination. The remainder has low water extractability (≤8%). The high water extractability(26–27%) of Zn in the radicle and coleoptile indicates its mobility in the seedling. Zn migrates from the aleurone to the pericarp and embryonic tissues, while Fe isdominantly present in the scutellum tissue attached to the seedling. The co-localisation of Zn and sulfur (S) in the developing embryo suggests that translocated Zn isbound to S-containing peptides. In aleurone cells Fe remains phytate bound and although Zn is phytate and S-bound, slight changes in its speciation occur duringgermination. This study partially explains the impact of steeping and germination on mineral bio-accessibility and opens possibilities for enhancing nutritionalquality during food processing., Published by Academic Press, London

International audience; Manganese (Mn) is an essential metal that can be neurotoxic when elevated exposition occurs leading to parkinsonian-like syndromes. Mutations in the Slc30a10 gene have been identified in new forms of familial parkinsonism. SLC30A10 is a cell surface protein involved in the efflux of Mn and protects the cell against Mn toxicity. Disease-causing mutations block the efflux activity of SLC30A10, resulting in Mn accumulation. Determining the intracellular localization of Mn when disease-causing SLC30A10 mutants are expressed is essential to elucidate the mechanisms of Mn neurotoxicity. Here, using organelle fluorescence microscopy and synchrotron X-ray fluorescence (SXRF) imaging, we found that Mn accumulates in the Golgi apparatus of human cells transfected with the disease-causing SLC30A10-Δ105–107 mutant under physiological conditions and after exposure to Mn. In cells expressing the wild-type SLC30A10 protein, cellular Mn content was low after all exposure conditions, confirming efficient Mn efflux. In nontransfected cells that do not express endogenous SLC30A10 and in mock transfected cells, Mn was located in the Golgi apparatus, similarly to its distribution in cells expressing the mutant protein, confirming deficient Mn efflux. The newly developed SXRF cryogenic nanoimaging (

Coordination chemistry underlies the structure/function of biological metal complexes. Contextualising this chemical information within an organism's physiology is critical for enhancing the understanding of bioinorganic chemistry but few high-fidelity probes are available. Here we develop fluorescence X-ray absorption near-edge structure tomography as a means for studying the spatial arrangement of biological coordination chemistry within intact organisms, and demonstrate the approach by mapping the distribution of cuprous and cupric complexes within Drosophila melanogaster.

A portrait of Henry VIII on oak panel c. 1535 has recently undergone technical examination to inform questions regarding authorship and the painting’s relationship to a group of similar works in the collections of the National Portrait Gallery, London, and the Society of Antiquaries. Due to previous conservation treatments of the painting, the conventional transmission X-radiograph image was difficult to interpret. As a result, the painting underwent high-definition X-ray fluorescence (XRF) elemental mapping on the X-ray fluorescence microscopy beamline of the Australian Synchrotron. Scans were conducted at 12.6 and 18.5 keV, below and above the lead (Pb) L edges, respectively. Typical scan parameters were 120 μm pixel size at 7 ms dwell time, with the largest scan covering an area 545 × 287 mm2 collected in 23 h (10.8 MP). XRF mapping of the panel has guided the conservation treatment of the painting and the revelation of previously obscured features. It has also provided insight into the process of making of the painting. The informative and detailed elemental maps, alongside ultra-high-definition scans of the painting undertaken before and after varnish and over-paint removal, have assisted in comparison of the finely painted details with the London paintings. The resolution offered by the combination of imaging techniques identifies pigment distribution at an extremely fine scale, enabling a new understanding of the artist’s paint application.

The journal of physical chemistry / C 122(43), 24801 - 24808 (2018). doi:10.1021/acs.jpcc.8b07863, The preparation of bimetallic nanoporous networks (BNNs) that combine the high surface area and thermal stability of inorganic nanostructures with the unique catalytic properties of bimetallic systems is highly desirable. Here we show a simple and highly versatile approach for synthesis of Pt–Re BNN and demonstrate the influence of preparation conditions on the BNN structure, composition, and catalytic reactivity. Pt–Re BNN was prepared by reduction of double complex [Pt(NH3)4][Re(Cl6)] salt crystals, in which two oppositely charged metal complexes are evenly distributed in each unit cell in a 1:1 ratio. Exposure of the salt crystals to reducing conditions induced the evaporation of the inorganic ligands, collapse of the salt structure, and reduction of the metal ions for the formation of high-surface-area Pt–Re BNNs. Single-particle X-ray fluorescence tomography and various ensemble-based spectroscopy measurements (X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy) identified that the bulk and surface compositions of the bimetallic structure and the oxidation state of the two metals can be tuned by adjusting the reduction temperature of the bimetallic salt. Pt–Re BNN showed reactivity in deoxydehydration reaction of glycerol toward the selective formation of allyl alcohol. Combination of reactivity and spectroscopic measurements revealed that enhanced reactivity was correlated to the presence of highly oxidized Re species (mostly Re7+) and equal distribution of Pt and Re on the BNN surface., Published by ACS, Washington, DC

Interface 15(138), 20170626 (2018). doi:10.1098/rsif.2017.0626, Cementum and the incremental markings it contains have been widely studied as a means of ageing animals and retrieving information about diet and nutrition. The distribution of trace elements in great ape and fossil hominin cementum has not been studied previously. Synchrotron X-ray fluorescence (SXRF) enables rapid scanning of large tissue areas with high resolution of elemental distributions. First, we used SXRF to map calcium, phosphorus, strontium and zinc distributions in great ape dentine and cementum. At higher resolution, we compared zinc and strontium distributions in cellular and acellular cementum in regions where clear incremental markings were expressed. We then mapped trace element distributions in fossil hominin dentine and cementum from the 1.55–1.65 million year old site of Koobi Fora, Kenya. Zinc, in particular, is a precise marker of cementum increments in great apes, and is retained in fossil hominin cementum, but does not correspond well with the more diffuse fluctuations observed in strontium distribution. Cementum is unusual among mineralized tissues in retaining so much zinc. This is known to reduce the acid solubility of hydroxyapatite and so may confer resistance to resorption by osteoclasts in the dynamic remodelling environment of the periodontal ligament and alveolar bone., Published by The Royal Society, London

Food chemistry 264, 367 - 376 (2018). doi:10.1016/j.foodchem.2018.04.125, Chelation of iron and zinc in wheat as phytates lowers their bio-accessibility. Steeping and germination (15 °C, 120 h) lowered phytate content from 0.96% to only 0.81% of initial dry matter. A multifactorial experiment in which (steeped/germinated) wheat was subjected to different time (2–24 h), temperature (20–80 °C) and pH (2.0–8.0) conditions showed that hydrothermal processing of germinated (15 °C, 120 h) wheat at 50 °C and pH 3.8 for 24 h reduced phytate content by 95%. X-ray absorption near-edge structure imaging showed that it indeed abolished chelation of iron to phytate. It also proved that iron was oxidized during steeping, germination and hydrothermal processing. It was further shown that zinc and iron bio-accessibility were respectively 3 and 5% in wheat and 27 and 37% in hydrothermally processed wheat. Thus, hydrothermal processing of (germinated) wheat paves the way for increasing elemental bio-accessibility in whole grain-based products., Published by Elsevier, New York, NY [u.a.]

The Maia large solid-angle detector array and imaging system is capable of collecting high-resolution images of up to ∼100 M pixels in size with dwell times of less than 0.2 ms per pixel and thus it is possible to document variation in textures associated with trace element chemistry by collecting quantified elemental maps of geological samples on the scale of entire thin sections in a short time frame (6–8 hr). The analysis is nondestructive and allows variation to be recognised on a centimetre scale while also recognising zonations at the micron scale. Studies of ore systems require microanalysis of samples to collect information on mineral chemistry in order to understand physiochemical conditions during ore genesis and alteration. Such studies contribute to the debate on whether precious metals are remobilised or introduced in multiple hydrothermal events. In this study we demonstrate the microanalytical capabilities of the Maia large solid-angle detector array and imaging system on the X-ray fluorescence microscopy beamline at the Australian Synchrotron to provide data for these studies. We present a series of case studies from orogenic gold deposits that illustrate the power of the Maia detector for constraining chemical zonations in sulphides and associated alteration minerals, which can be used to decipher ore-forming processes associated with gold deposition. A series of large-area (

International Conference X-Ray Microscopy, XRM2018, Saskatoon, Canada, 19 Aug 2018 - 24 Aug 2018; Microscopy and microanalysis 24(S2), 390 - 391 (2018). doi:10.1017/S143192761801423X, The nature of retinal shielding pigment in the larval eyes of the midge Clunio marinus was studied by high resolution scanning X-ray fluorescence (XRF) analysis correlated with light microscopy and scanning coherent X-ray diffractive imaging (Ptychography). Clunio is known as a unique model system to decipher mechanisms underlying the complex moon-related rhythms. Shielding pigment granules within the photoreceptor cells of their primitive eyes (ocelli) have been shown to change appearance in the same rhythm [1]. The larvae are equipped with simple pigment-cup eyes (ocelli) in which the dense shielding pigment permits light access to the photosensitive rhabdomers only through a narrow pinhole resulting in a diffuse image of the environment. The pigment cup of these eyes becomes transparent during full moon [2]. Within the photoreceptor cells of the ocelli, melanin containing melanosomes form shielding pigment granules. Melanin is a nearly universally occurring pigment in different organisms and organ systems with several known functions; not only as shield against bright light (especially UV-light), but also as reservoir or sink of excessive amounts of metals, and as a component of the immune system [3]. Trace metals have been shown to be indicators of certain steps of melanogenesis. The aim of this study is to combine different non-destructive microscopy techniques to analyse the process of melanogenesis with single melanin granule-resolution., Published by Cambridge University Press, New York, NY

• Accumulation of arsenic (As) within plant tissues represents a human health risk, but there remains much to learn regarding the speciation of As within plants. • We developed synchrotron-based fluorescence-X-ray absorption near-edge spectroscopy (fluorescence-XANES) imaging in hydrated and fresh plant tissues to provide laterally resolved data on the in situ speciation of As in roots of wheat (Triticum aestivum) and rice (Oryza sativa) exposed to 2 μM As(V) or As(III). • When exposed to As(V), the As was rapidly reduced to As(III) within the root, with As(V) calculated to be present only in the rhizodermis. However, no uncomplexed As(III) was detected in any root tissues, because of the efficient formation of the As(III)-thiol complex - this As species was calculated to account for all of the As in the cortex and stele. The observation that uncomplexed As(III) was below the detection limit in all root tissues explains why the transport of As to the shoots is low, given that uncomplexed As(III) is the major As species transported within the xylem and phloem. • Using fluorescence-XANES imaging, we have provided in situ data showing the accumulation and transformation of As within hydrated and fresh root tissues.

The aim of this study was to analyse the tissue surrounding the University of Melbourne's (UOMs) multi-channel cochlear implant electrode array and cochlear limited replacements, after long-term implantations. In particular, it aimed to identify the particulate material in the fibrous tissue capsule of the arrays implanted in 1978, 1983, and 1998, by using the Australian Synchrotron for X-ray fluorescence microscopy (XFM) to reveal the characteristic spectrum of metal, in particular platinum. This also helped to determine its format and chemical state. Tissue was retrieved following the recipient's death in 2007.Tissue was fixed and sections taken across the UOM and Cochlear Corporation (CI-22 and CI-24) electrode tracks. These were stained with Masson's trichrome. The Australian Synchrotron enabled XFM to accurately identify platinum from its characteristic fluorescence spectrum.There was a fibrous tissue capsule (about 100-µm thick) and small regions of calcification around the UOM and CI-22 arrays, but a thinner capsule (40-60-µm thick) around CI-24, and a greater degree of calcification. Dark particulate matter was observed within macrophages and especially in fibrous tissue in proximity to the UOM and CI-22 arrays. This was identified as platinum using X-ray fluorescence. There was also diffusion of platinum into the tissue surrounding the UOM and CI-22 electrodes and fine particles had penetrated the spiral ligament.The larger particulate matter in the tissue around the UOM and CI-22 arrays suggested that it had flaked off in the manufacturing of the UOM electrodes. The more diffuse spread of platinum in the tissue around the UOM and CI-22 electrodes was likely due to electrolysis, probably from charge imbalance with the bipolar pulses from the UOM implant. This did not occur with the Cochlear CI-24 device. Furthermore, the widespread fine particles of platinum could have also been due to corrosion, especially from the UOM electrodes.

All possible iron environments with respect to nearest neighbour vacancies in vacancy-ordered and vacancy-disordered maghemite have been evaluated and used as the foundation for a crystallographically-based analysis of the published NMR spectra of maghemite. The spectral components have been assigned to particular configurations and excellent agreement obtained in comparing predicted spectra with published spectra taken in applied magnetic fields. The broadness of the published NMR lines has been explained by calculations of the magnetic dipole fields at the various iron sites and consideration of the supertransferred hyperfine fields.

Magnetic microspheres, with mean particle sizes from 23 to 32 μm were produced by the ultrasonic atomisation of a suspension of magnetite particles, of approximately 200 nm diameter, in a solution of poly– l –lactic acid (PLLA). The mean particle diameter and the width of the particle diameter distribution both increased with increasing magnetite concentration. The particles appear to be suitable for magnetic hyperthermic treatment of liver cancers, with the hysteresis loop areas increasing linearly with nominal magnetite concentration up to 30 wt% magnetite.

X-ray fluorescence (XRF) was used to image 40 histological cross-sections of bovine ovaries (n=19), focusing on structures including: antral follicles at different stages of growth or atresia, corpora lutea at three stages of development (II–IV), and capillaries, arterioles, and other blood vessels. This method identified three key trace elements [iron (Fe), zinc (Zn), and selenium (Se)] within the ovarian tissue which appeared to be localized to specific structures. Owing to minimal preprocessing of the ovaries, important high-resolution information regarding the spatial distribution of these elements was obtained with elemental trends and colocalizations of Fe and Zn apparent, as well as the infrequent appearance of Se surrounding the antrum of large follicles, as previously reported. The ability to use synchrotron radiation to measure trace element distributions in bovine ovaries at such high resolution and over such large areas could have a significant impact on understanding the mechanisms of ovarian development. This research is intended to form a baseline study of healthy ovaries which can later be extended to disease states, thereby improving our current understanding of infertility and endocrine diseases involving the ovary.

Vector-field electron tomography (VFET) reconstructs electromagnetic vector fields of magnetic nanomaterials using transmission electron microscopy. The theory behind this reconstruction process is well established, but the practical implications of experimental errors and how they affect the accuracy of the reconstructed vector fields is not well understood, hindering progress in the use of these techniques for routine magnetic characterization of nanomaterials. Here, we present an analysis of the propagation of stochastic errors through a VFET algorithm. A method for determining the contribution of image noise to errors in a reconstructed vector potential is derived. Simulations are performed to test the validity of this method when applied to shot noise, which shows good agreement with theory.

X-ray fluorescence images acquired using the Maia large solid-angle detector array and integrated real-time processor on the X-ray Fluorescence Microscopy (XFM) beamline at the Australian Synchrotron capture fine detail in complex natural samples with images beyond 100M pixels. Quantitative methods permit real-time display of deconvoluted element images and for the acquisition of large area XFM images and 3D datasets for fluorescence tomography and chemical state (XANES) imaging. This paper outlines the Maia system and analytical methods and describes the use of the large detector array, with a wide range of X-ray take-off angles, to provide sensitivity to the depth of features, which is used to provide an imaging depth contrast and to determine the depth of rare precious metal particles in complex geological samples.

Our group is concerned with addressing the limitations of current x‐ray imaging devices for Coherent X‐ray Diffractive Imaging (CXDI). CCDs are well established in this area of research. However the signal to noise ratio and dynamic range of integrating devices are sub‐optimal for CXDI. For successful CXDI image reconstruction the recorded signal should be accurately measured over a wide dynamic range. This is best achieved by measuring precisely the number of photons registered by a pixel. Accurate data sets allow reconstruction algorithms to converge in a shorter time than if noisy estimates of the intensities are used. Using modern very large scale integrated circuit (VLSI) technology complex pixel readout circuitry can be fabricated with a footprint of less than 100 microns square. Placing an x‐ray sensitive material above such a circuit matrix and electrically or optically connecting to it, produces a versatile and accurate x‐ray detector. The name given to such a device is a hybrid pixel detector (HPD). We have chosen the MEDIPIX2 HPD to assess against the demands of CXDI. This paper reports on laboratory tests of a device with a 300 micron thick silicon as the x‐ray converter, and an array of 256×256 pixels each of 55 microns square.

Electric field gradient (EFG) lattice sums for the vacancy-disordered and vacancy-ordered forms of maghemite were evaluated using a point charge model. The calculated EFGs produced a wide range of magnitudes and principal directions for the quadrupole interaction for both forms of maghemite. Small perturbations of the crystallographic parameters were shown to have a significant effect on the quadrupole shift. The effects observed were significant enough to show that quadrupole shifts should be considered when fitting the Mössbauer spectra of maghemite.