Synchrotron X-ray Fluorescence Mapping Research Articles

Influence of fracturing fluids on shale matrix permeability and micro-mechanical properties after chemical interactions

Geochemical interactions between shale and hydraulic fracture fluids (HFFs), principally mineral dissolution and precipitation, can result in alteration of matrix permeability and tendency of proppant embedment, ultimately impacting hydrocarbon migration through the shale formation. This study aimed to quantify changes of core permeability and micromechanical properties after shale-HFF chemical interactions. Extent of chemical alteration of the solid phase was characterized by synchrotron X-ray fluorescence mapping, micro-computed tomography, and scanning electron microscopy. Post-reaction brine was evaluated for elemental concentrations. Both low-carbonate and high-carbonate shale exhibited carbonate dissolution, an iron oxidation zone, and barite precipitates partially infilling secondary porosity. These reactions were more obvious in the high-carbonate shale but extended further into the low-carbonate shale. Pulse-decay permeability measurements generally revealed increase in permeability after reactions, whereas hardness and modulus reduction were observed only in reaction zones of high carbonate shale. Inevitable heterogeneity of natural shale samples resulted in large deviations in hydromechanical measurements both on the core scale and on the microscale.

An uneven distribution of strontium in the coccolithophore Scyphosphaera apsteinii revealed by nanoscale X-ray fluorescence tomography.

Coccolithophores are biogeochemically and ecologically important phytoplankton that produce a composite calcium carbonate-based exoskeleton - the coccosphere - comprised of individual platelets, known as coccoliths. Coccoliths are stunning examples of biomineralization; their formation featuring exceptional control over both biomineral chemistry and shape. Understanding how coccoliths are formed requires information about minor element distribution and chemical environment. Here, the first high-resolution 3D synchrotron X-ray fluorescence (XRF) mapping of a coccolith is presented, showing that the lopadoliths of Scyphosphaera apsteinii display stripes of different Sr concentration. The presence of Sr stripes is unaffected by elevated Sr in the culture medium, macro-nutrient concentration, and light intensity, indicating that the observed stripiness is an expression of the fundamental coccolith formation process in this species. Current Sr fractionation models, by contrast, predict an even Sr distribution and will have to be modified to account for this stripiness. Additionally, nano-XANES analyses show that Sr resides in a Ca site in the calcite lattice in both high and low Sr stripes, confirming a central assumption of current Sr fractionation models.

Arsenic sorption and oxidation by natural manganese-oxide-enriched soils: Reaction kinetics respond to varying environmental conditions

Manganese-oxides are some of the strongest oxidants and sorbents in the environment, which impact many geochemical processes. However, nearly all our understanding of manganese-oxides’ reaction kinetics is based on laboratory-synthesized minerals. This study quantifies the oxidative kinetics and adsorptive capacity of five soils rich in pedogenic manganese- and iron-oxides through arsenite oxidation batch reactions over a range of pHs and temperatures to mimic diverse environmental conditions. The two A horizons were less reactive and enriched in manganese(IV), compared to the B horizons, particularly the subsoil containing the manganese-rich wad material. The reaction kinetics fit a pseudo-first-order reaction with distinct fast and slow phases. The baseline reactions were pH 7.2 at 23 °C. Adjusting pH to 4.5 or 9.0 increased the reaction rates. Decreasing the temperature to 4.0 °C reduced the reaction kinetics, while raising the temperature to 40 °C increased the arsenite oxidation rate. pH and temperature changes alter the reaction kinetics due to shifts related to the point of zero charge, the total system energy, and surface passivation from adsorbing arsenic and manganese species. Synchrotron X-ray fluorescence mapping indicates arsenic only penetrates the surficial layers of most manganese-oxide-containing nodules found in the soil. After the arsenite oxidation reaction in the pedogenically weathered subsoil, X-ray absorption spectroscopy demonstrates significant differences in the average manganese oxidation number between the nodules’ outer layers compared to the soil matrix and nodule centers. The kinetic and sorption parameters give critical insight into determining the mobility and species of arsenic and other redox-sensitive contaminants in manganese-containing environmental systems over appropriate timescales.

Cobalt and Chromium Ions Impair Macrophage Response to Staphylococcus aureus Infection.

Cobalt-chromium-molybdenum (CoCrMo) alloys are routinely used in arthroplasty. CoCrMo wear particles and ions derived from arthroplasty implants lead to macrophage-driven adverse local tissue reactions, which have been linked to an increased risk of periprosthetic joint infection after revision arthroplasty. While metal-induced cytotoxicity is well characterized in human macrophages, direct effects on their functionality have remained elusive. Synchrotron radiation X-ray microtomography and X-ray fluorescence mapping indicated that peri-implant tissues harvested during aseptic revision of different arthroplasty implants are exposed to Co and Cr in situ. Confocal laser scanning microscopy revealed that macrophage influx is predominant in patient tissue. While in vitro exposure to Cr3+ had only minor effects on monocytes/macrophage phenotype, pathologic concentrations of Co2+ significantly impaired both, monocyte/macrophage phenotype and functionality. High concentrations of Co2+ led to a shift in macrophage subsets and loss of surface markers, including CD14 and CD16. Both Co2+ and Cr3+ impaired macrophage responses to Staphylococcus aureus infection, and particularly, Co2+-exposed macrophages showed decreased phagocytic activity. These findings demonstrate the immunosuppressive effects of locally elevated metal ions on the innate immune response and support further investigations, including studies exploring whether Co2+ and Cr3+ or CoCrMo alloys per se expose the patients to a higher risk of infections post-revision arthroplasty.

Micro-scale structural and chemical characterisation of deformed rocks with simultaneous in-situ synchrotron X-ray fluorescence and backscatter diffraction mapping

In-situ measurements of structural and chemical information on deformed rocks are required to understand microphysical deformation mechanisms, the relative timing of tectono-metamorphic events, and the interplay between deformation, fluid flow, and mineral reactions. Scanning-electron microscopy is commonly used for this purpose, because it can provide compositional information (via energy- or wavelength-dispersive spectroscopy and backscattered electron imaging) and crystallographic orientation data (via electron backscatter diffraction) for large fractions of thin sections down to nanometre resolution. However, elemental and crystal-structural data are usually acquired independently, introducing the need for registration of maps with different information and increasing instrument time. In addition, measuring element concentrations to levels below 1000 ppm increases acquisition times significantly, rendering the mapping of centimetre-scale areas with micrometre-resolution or below time-costly. Here, we introduce an alternative method using coeval synchrotron X-ray fluorescence microscopy (XFM) and X-ray backscatter diffraction mapping (XBDM) for the rapid acquisition of structural and compositional information down to the ppb level on whole rock sections with a spatial resolution down to ∼1 μm per pixel. We illustrate the principles of XFM/XBDM mapping on a sample of granitic mylonite. As example for the scientific potential of the new method, it is shown that the Ti distribution in quartz and feldspar can be accurately correlated with physical structure. A discussion of the limitations and opportunities of XFM/XBDM mapping for studying deformed rocks concludes this article.

Thorium speciation in ilmenite concentrates from the Mandena deposit, Madagascar: Implications for environmental remediation and thorium beneficiation

Placer ilmenite deposits are important sources for titanium dioxide production but are often radioactive due to elevated thorium and uranium contents, posing significant challenges to their upgrading and downstream commercial applications. In this contribution, we have investigated ilmenite concentrates containing 133 ppm Th and 12.8 ppm U from the Mandena deposit, Madagascar, using a wide range of analytical techniques: powder X-ray diffraction, electron microprobe analysis, quantitative evaluation of materials by scanning electron microscopy, inductively coupled plasma mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, synchrotron X-ray absorption spectroscopy, microbeam synchrotron X-ray fluorescence mapping, and microbeam synchrotron Laue X-ray diffraction analysis. Our data show that monazite-(Ce), mainly as discrete grains, accounts for ∼55% of Th in the Mandena ilmenite concentrates. Thorianite hosting the remaining Th at ∼45% is revealed by synchrotron Th LIII edge X-ray absorption near-edge structure and extended X-ray absorption fine structure analyses and is correlated with the degree of ilmenite alteration. These results suggest that thorianite probably formed from the alteration of ilmenite and precipitated on the surface of altered ilmenite. The presence of monazite-(Ce) and thorianite in the Mandena ilmenite concentrates is further supported by principal component analysis of trace elements. Our results suggest that combined magnetic separation and acid leaching are effective for reducing the Th (and U) abundances in the Mandena ilmenite concentrates, via the removal of Th-bearing minerals. These findings have important implications for both Th remediation and beneficiation. Moreover, the precipitation of thorianite on the surface of altered ilmenite is an effective method for attenuating the common radionuclide Th in surficial environments.

Flash NanoPrecipitation as an Agrochemical Nanocarrier Formulation Platform: Phloem Uptake and Translocation after Foliar Administration.

The increasing severity of pathogenic and environmental stressors that negatively affect plant health has led to interest in developing next-generation agrochemical delivery systems capable of precisely transporting active agents to specific sites within plants. In this work, we adapt Flash NanoPrecipitation (FNP), a scalable nanocarrier (NC) formulation technology used in the pharmaceutical industry, to prepare organic core-shell NCs and study their efficacy as foliar or root delivery vehicles. NCs ranging in diameter from 55 to 200 nm, with surface zeta potentials from -40 to +40 mV, and with seven different shell material properties were prepared and studied. Shell materials included synthetic polymers poly(acrylic acid), poly(ethylene glycol), and poly(2-(dimethylamino)ethyl methacrylate), naturally occurring compounds fish gelatin and soybean lecithin, and semisynthetic hydroxypropyl methylcellulose acetate succinate (HPMCAS). NC cores contained a gadolinium tracer for tracking by mass spectrometry, a fluorescent dye for tracking by confocal microscopy, and model hydrophobic compounds (alpha tocopherol acetate and polystyrene) that could be replaced by agrochemical payloads in subsequent applications. After foliar application onto tomato plants with Silwet L-77 surfactant, internalization efficiencies of up to 85% and NC translocation efficiencies of up to 32% were observed. Significant NC trafficking to the stem and roots suggests a high degree of phloem loading for some of these formulations. Results were corroborated by confocal microscopy and synchrotron X-ray fluorescence mapping. NCs stabilized by cellulosic HPMCAS exhibited the highest degree of translocation, followed by formulations with a significant surface charge. The results from this work indicate that biocompatible materials like HPMCAS are promising agrochemical delivery vehicles in an industrially viable pharmaceutical nanoformulation process (FNP) and shed light on the optimal properties of organic NCs for efficient foliar uptake, translocation, and delivery.

Flexible design in the stomatopod dactyl club.

The stomatopod is a fascinating animal that uses its weaponized appendage dactyl clubs for breaking mollusc shells. Dactyl clubs are a well studied example of biomineralized hierarchical structures. Most research has focused on the regions close to the action, namely the impact region and surface composed of chitin and apatite crystallites. Further away from the site of impact, the club has lower mineralization and more amorphous phases; these areas have not been as actively studied as their highly mineralized counterparts. This work focuses on the side of the club, in what is known as the periodic and striated regions. A combination of laboratory micro-computed tomography, synchrotron X-ray diffraction mapping and synchrotron X-ray fluorescence mapping has shown that the mineral in this region undergoes the transition from an amorphous to a crystalline phase in some, but not all, clubs. This means that this side region can be mineralized by either an amorphous phase, calcite crystallites or a mixture of both. It was found that when larger calcite crystallites form, they are organized (textured) with respect to the chitin present in this biocomposite. This suggests that chitin may serve as a template for crystallization when the side of the club is fully mineralized. Further, calcite crystallites were found to form as early as 1 week after moulting of the club. This suggests that the side of the club is designed with a significant safety margin that allows for a variety of phases, i.e. the club can function independently of whether the side region has a crystalline or amorphous mineral phase.

Microbial Activity and Neomorphism Influence the Composition and Microfabric of Ooids From Great Salt Lake, UT

The sediment along the shorelines of Great Salt Lake (GSL), Utah is dominated by ooids, concentrically-coated carbonate sand grains. Two characteristics differentiate GSL ooids from typical modern marine ooids: well-developed radial aragonite microfabrics and the ubiquitous occurrence of a Mg-silicate phase. The radial microfabrics have formed the basis of conceptual models applied to understand the formation of radial fabrics in ancient ooids, but the formation of the Mg-silicates, and the relationship between Mg-silicates and radial aragonite crystals have received little attention. The occurrence of Mg-silicates in GSL ooids is surprising because GSL lake water pH is ~8.3, too low for Mg-silicate precipitation (requires pH>8.7). We use transmitted light microscopy, element mapping via wavelength-dispersive x-ray spectroscopy with electron microprobe, scanning electron microscopy, and synchrotron x-ray fluorescence (XRF) mapping and sulfur K-edge absorption spectroscopy to explore the spatial relationships between the mineral phases in GSL ooids. We observe large euhedral aragonite crystals penetrating Mg-silicate zones and cutting across laminar cortices, suggesting that the characteristic radial aragonitic fabrics in GSL ooids, traditionally interpreted as a primary structure, are enhanced, or in some cases entirely created via neomorphism. XRF maps reveal that Mg-silicate zones co-occur with elemental sulfur (S0), which we interpret as a metabolic intermediate of microbial sulfur cycling. This co-occurrence supports our hypothesis that microbial sulfur cycling plays a key role in the formation of GSL ooids by locally shifting pH beyond the threshold for Mg-silicate precipitation. This compositional fingerprint could serve as a biosignature in ancient lacustrine strata where Mg-silicates co-occur with carbonate minerals.

Natural nanoparticles of the critical element tellurium

Tellurium (Te) is a Critical Element that is toxic to microorganisms and humans alike, most notably in its soluble oxyanionic forms. To date, the biogeochemical behaviour of Te in Earth’s surface environment is largely unknown. Here, we report the discovery of elemental Te nanoparticles (Te NPs) in regolith samples using Single-Particle Inductively Coupled Plasma Mass Spectroscopy. Tellurium NPs were detected in both proximal and distal locations (bulk concentrations >4 ppm) relative to weathering Te ores. Synchrotron X-ray Fluorescence Mapping and X-ray Absorption Spectroscopy showed that bulk Te in the regolith is generally associated with Fe (oxyhydr)oxides and clay minerals, and mostly found in the oxidation states +IV and +VI. Although Te NPs account for less than 2 mol‰ of Te in our samples, their detection provides evidence for the active biogeochemical cycling of Te in surface environments. Te NPs are reactive and are likely to have formed in situ in distal samples, most likely via microbially-mediated reduction. Hence, the presence of Te NPs indicates the potential for release of toxic soluble forms of Te even in environments where most Te is “fixed” in forms such as Fe (oxyhydr)oxides that have low solubility and poor bioavailability.

Core characterisation and predicted CO2 reactivity of sandstones and mudstones from an Australian oil field

CO2 geological storage has been proposed as one method to mitigate climate change. Storage of CO2 in depleted oil or gas fields is one option, potentially following enhanced recovery. Understanding the potential impacts of CO2 water rock reactions is an important aspect of storage feasibility studies. Drill core samples of sandstones and mudstones from the Jurassic Moonie oil field, Australia, were characterised. In the Precipice Sandstone reservoir samples pore throats had broad size distributions, with mercury intrusion porosities 6.2 to 14.6%. Evergreen Formation samples were more variable with 1.2 to 16.1% porosity. Porosities measured by QEMSCAN were in reasonable agreement at 8.6 to 15.3% for Precipice Sandstones, and 0.6 to 21.5 for the Evergreen Formation. Sandstones had larger pore throat sizes and lower threshold pressures indicative of good reservoir rocks. Calcite cemented sandstones had truncated pore throat distributions, and the coal and clay rich mudstones had pore throats <0.1 μm with higher threshold pressures likely to seal or baffle CO2. Quartz grains were naturally fractured, with silica, apatite, rutile, calcite, and siderite cements filling porosity in some samples. Feldspars had been weathered producing secondary porosity but also resulting in kaolinite and illite filling intergranular porosity. Pyrite and barite were mainly associated with coals. Synchrotron X-ray fluorescence mapping showed Sr was mainly hosted in calcite cement, apatite and barite; with Rb in both plagioclase and K-feldspars. Calcite mainly hosted Mn; while Zn and Cu were mainly in sulphides. Sulphide minerals in coal also hosted As in one core. Kinetic geochemical CO2-water-rock modelling using the characterisation data over 30 or 1000 years indicated reaction of carbonate minerals where present, and alteration of mainly plagioclase, K-feldspar and chlorite. Net precipitation of ankerite, calcite or siderite mineral trapped 0.23 to 1.28 kg/m3 of CO2 after 1000 years in the different rock packages and was highest in Evergreen Formation rocks. The predicted pH was in the range 5.0 to 5.4 after 1000 years, or higher at 5.2 to 7.1 in lower CO2 fugacity models. Sandstone reactivity was overall low over 30 years indicating a low likelihood of reservoir scaling which would be favourable, with mineral trapping likely in the overlying Evergreen Formation.

Extreme-resolution synchrotron X-Ray fluorescence mapping of ore samples

In order to maximise profit and sustainability of a mining operation, knowledge of the chemistry, mineralogy, texture, and structure of the ore is essential. Continuous advancements in analytical techniques enable studying these features with increasing detail. Synchrotron radiation X-ray fluorescence is unparalleled in its simultaneously high spatial resolution and detection range. Yet, its application in ore geology research and the mining industry is still in its infancy. This study investigated opportunities of extreme-resolution synchrotron X-ray fluorescence mapping of ore samples. Analysis was performed at the NanoMAX beamline at the MAX IV synchrotron facility in Lund, Sweden. The samples investigated are from the Liikavaara Östra Cu-(W-Au) deposit, northern Sweden. Analysis covered areas of several hundreds of μm2 in grains of molybdenite, pyrite, and native Bi. Key results included successful mapping of the lattice-bound distribution of Re, Se, and W in molybdenite at 200 nm spot/step size and detection of nanometre inclusions of Au in native Bi at 50 nm spot/step size. Challenges were encountered concerning data acquisition and processing. In order to achieve satisfactory resolution of both light and heavy elements and to limit mapping artefacts, repeated scans of the same area with varied experimental parameters and very thin (quasi-2d) samples are required. For complex geological samples, the software used for analysing spectral data (PyMCA) requires a considerable degree of human examination, which may be a source of error. Overall, synchrotron X-ray fluorescence mapping has a strong analytical potential for ore geology research, in analysing and imaging trace elements that would constitute potential by-products in mining operations. Detailed knowledge of how trace elements occur in the ores will inform the development of appropriate metal extraction programs thus ensuring that a larger part of the ore may then be utilized.

Arabidopsis thaliana zinc accumulation in leaf trichomes is correlated with zinc concentration in leaves

Zinc (Zn) is a key micronutrient for plants and animals, and understanding Zn homeostasis in plants can improve both agriculture and human health. While root Zn transporters in plant model species have been characterized in detail, comparatively little is known about shoot processes controlling Zn concentrations and spatial distribution. Previous work showed that Zn hyperaccumulator species such as Arabidopsis halleri accumulate Zn and other metals in leaf trichomes. To date there is no systematic study regarding Zn accumulation in the trichomes of the non-accumulating, genetic model species A. thaliana. Here, we used Synchrotron X-Ray Fluorescence mapping to show that Zn accumulates at the base of trichomes of A. thaliana. Using transgenic and natural accessions of A thaliana that vary in bulk leaf Zn concentration, we demonstrate that higher leaf Zn increases total Zn found at the base of trichome cells. Our data indicates that Zn accumulation in trichomes is a function of the Zn status of the plant, and provides the basis for future studies on a genetically tractable plant species to understand the molecular steps involved in Zn spatial distribution in leaves.

Developing a system for in vivo imaging of maize roots containing iodinated contrast media in soil using synchrotron XCT and XRF

AimsWe sought to develop a novel experimental system which enabled application of iodinated contrast media to in vivo plant roots intact in soil and was compatible with time-resolved synchrotron X-ray computed tomography imaging. The system was developed to overcome issues of low contrast to noise within X-ray computed tomography images of plant roots and soil environments, the latter of which can complicate image processing and result in the loss of anatomical information.MethodsTo demonstrate the efficacy of the system we employ the novel use of both synchrotron X-ray computed tomography and synchrotron X-ray fluorescence mapping to capture the translocation of the contrast media through root vasculature into the leaves.ResultsWith the application of contrast media we identify fluid flow in root vasculature and visualise anatomical features, which are otherwise often only observable in ex vivo microscopy, including: the xylem, metaxylem, pith, fibres in aerenchyma and leaf venation. We are also able to observe interactions between aerenchyma cross sectional area and solute transport in the root vasculature with depth.ConclusionsOur novel system was capable of successfully delivering sufficient contrast media into root and leaf tissues such that anatomical features could be visualised and internal fluid transport observed. We propose that our system could be used in future to study internal plant transport mechanisms and parameterise models for fluid flow in plants.

Uranyl binding mechanism in microcrystalline silicas: A potential missing link for uranium mineralization by direct uranyl co-precipitation and environmental implications

Genetic models for the formation of uranium deposits almost invariably invoke the reduction of U(VI) to U(IV) as the deposition mechanism. However, the questions of when and how this reduction occurred are often not clear in most uranium deposits. For example, mineralization in the giant Olympic Dam Cu-U-Au-Ag deposit (Australia) occurs mainly in hematite-rich breccias of the oxidizing hematite-quartz-barite assemblage. Similarly, unconformity-related uranium deposits in the Athabasca Basin (Canada) are accompanied by extensive and intensive hematite- and quartz-rich alteration halos, pointing to a possible linkage between uranium mineralization and silicification. However, this linkage is not understood due to the lack of knowledge about the speciation and mechanism of uranium incorporation in microcrystalline and macrocrystalline silicas. In this contribution, microcrystalline silicas (agate and opal-CT) containing 27–137 ppm U have been investigated by microbeam synchrotron X-ray fluorescence mapping, microbeam synchrotron X-ray diffraction analysis, synchrotron X-ray absorption spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and electron paramagnetic resonance spectroscopy. These data unravel the binding mechanism of uranyl silicate complexes in microcrystalline silicas and suggest a new mechanism of uranium deposition involving uranyl co-precipitation without the putative reduction process, providing a potential missing link between uranium mineralization and silicification for the formation of uranium deposits. In addition, new data on the uptake and long-term retention of elevated uranyl contents in microcrystalline silicas extend previous findings from their amorphous counterparts on these materials as an effective sink for uranium attenuation to higher temperatures, important to the storage and disposal of heat-generating nuclear waste in deep geological repositories.

Visualizing mineralization processes and fossil anatomy using synchronous synchrotron X-ray fluorescence and X-ray diffraction mapping

Fossils, including those that occasionally preserve decay-prone soft tissues, are mostly made of minerals. Accessing their chemical composition provides unique insight into their past biology and/or the mechanisms by which they preserve, leading to a series of developments in chemical and elemental imaging. However, the mineral composition of fossils, particularly where soft tissues are preserved, is often only inferred indirectly from elemental data, while X-ray diffraction that specifically provides phase identification received little attention. Here, we show the use of synchrotron radiation to generate not only X-ray fluorescence elemental maps of a fossil, but also mineralogical maps in transmission geometry using a two-dimensional area detector placed behind the fossil. This innovative approach was applied to millimetre-thick cross-sections prepared through three-dimensionally preserved fossils, as well as to compressed fossils. It identifies and maps mineral phases and their distribution at the microscale over centimetre-sized areas, benefitting from the elemental information collected synchronously, and further informs on texture (preferential orientation), crystallite size and local strain. Probing such crystallographic information is instrumental in defining mineralization sequences, reconstructing the fossilization environment and constraining preservation biases. Similarly, this approach could potentially provide new knowledge on other (bio)mineralization processes in environmental sciences. We also illustrate that mineralogical contrasts between fossil tissues and/or the encasing sedimentary matrix can be used to visualize hidden anatomies in fossils.

Overexpression of the manganese/cadmium transporter OsNRAMP5 reduces cadmium accumulation in rice grain.

Rice is a major dietary source of the toxic metal cadmium (Cd), and reducing its accumulation in the grain is therefore important for food safety. We selected two cultivars with contrasting Cd accumulation and generated transgenic lines overexpressing OsNRAMP5, which encodes a major influx transporter for manganese (Mn) and Cd. We used two different promoters to control the expression, namely OsActin1 and maize Ubiquitin. Overexpression of OsNRAMP5 increased Cd and Mn uptake into the roots, but markedly decreased Cd accumulation in the shoots, whilst having a relatively small effect on Mn accumulation in the shoots. The overexpressed OsNRAMP5 protein was localized to the plasma membrane of all cell types in the root tips and lateral root primordia without polarity. Synchrotron X-ray fluorescence mapping showed that the overexpression lines accumulated more Cd in the root tips and lateral root primordia compared with the wild-type. When grown in three Cd-contaminated paddy soils, overexpression of OsNRAMP5 decreased concentration of Cd in the grain by 49-94% compared with the wild type. OsNRAMP5-overexpression plants had decreased Cd translocation from roots to shoots as a result of disruption of its radial transport into the stele for xylem loading, demonstrating the effect of transporter localization and polarity on ion homeostasis.

Imaging trace-element zoning in pyroxenes using synchrotron XRF mapping with the Maia detector array: Benefit of low-incident energy

Abstract Trace-element zoning in igneous phenocrysts and cumulus phases is an informative record of magmatic evolution. The advent of microbeam X-ray fluorescence (XRF) mapping has allowed rapid chemical imaging of samples at thin section to decimeter scale, revealing such zoning patterns. Mapping with synchrotron radiation using multidetector arrays has proved especially effective, allowing entire thin sections to be imaged at micrometer-scale resolution in a matter of hours. The resolution of subtle minor element zoning, particularly in first-row transition metals, is greatly enhanced in synchrotron X-ray fluorescence microscopy (XFM) images by scanning with input beam energy below the FeKα line. In the examples shown here, from a phenocryst rich trachybasalt from Mt Etna (Italy) and from a Ni-Cu-PGE ore-bearing intrusion at Norilsk (Siberia), the zoning patterns revealed in this way record aspects of the crystallization history that are not readily evident from XFM images collected using higher incident energies and that cannot be obtained at comparable spatial resolutions by any other methods within reasonable scan times. This approach has considerable potential as a geochemical tool for investigating magmatic processes and is also likely to be applicable in a wide variety of other fields.

Quantitative temporally and spatially resolved X-ray fluorescence microprobe characterization of the manganese dissolution-deposition mechanism in aqueous Zn/α-MnO2 batteries

Operando, spatiotemporal resolved synchrotron X-ray fluorescence mapping measurements on a custom aqueous Zn/α-MnO2 cell provided direct, quantitative evidence of a Mn dissolution-deposition faradaic mechanism that governs the electrochemistry.

Synchrotron X-ray fluorescence mapping of Ca, Sr and Zn at the neonatal line in human deciduous teeth reflects changing perinatal physiology

ObjectivesOur first objective was to review the evidence describing the appearance and microstructure of the neonatal line in human deciduous teeth and to link this with known changes in neonatal physiology occurring at and around birth. A second objective was to explore ways to improve identification of the neonatal line by mapping the pre- and postnatal distribution of Ca, Sr and Zn in deciduous cuspal enamel and superimposing these maps onto transmitted light micrographs that included a clear true section of the neonatal line. Materials and methodsWe used synchrotron X-ray fluorescence to map elemental distributions in pre- and postnatal enamel and dentine. Two deciduous canines and 5 deciduous molars were scanned with an X-ray beam monochromatised to 17.0 keV at either 10.0, 2.5 or 1.0 μm resolution and 10 ms integration time. ResultsCalcium maps distinguished enamel and dentine but did not clearly demarcate tissues formed pre- or postnatally. Strontium maps reflected presumed pre- and postnatal maternal serum levels and what are likely to be diet-dependent regions of Sr enrichment or depletion. Prenatal Zn maps, particularly for dentine, mirror elevated levels in the fetus and in colostrum during the first few days of life. ConclusionsThe neonatal line, enamel dentine junction and surface enamel were all Zn-rich. Within the neonatal line Zn may be associated with increased crystallinity but also with caries resistance, both of which have been reported previously. Elemental mapping may improve the identification of ambiguous NNLs and so be useful in forensic and archaeological studies.