I08-Scanning X-ray Microscopy beamline (SXM)
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Dawn M.
Buchanan
,
Laura
Newsome
,
Jonathan R.
Lloyd
,
Majid
Kazemian
,
Burkhard
Kaulich
,
Tohru
Araki
,
Heath
Bagshaw
,
John
Waters
,
Gerrit
Van Der Laan
,
Alpha
N’diaye
,
Victoria S.
Coker
Diamond Proposal Number(s):
[17626]
Open Access
Abstract: Cobalt is an essential element for life and plays a crucial role in supporting the drive to clean energy, due to its importance in rechargeable batteries. Co is often associated with Fe in the environment, but the fate of Co in Fe-rich biogeochemically-active environments is poorly understood. To address this, synchrotron-based scanning X-ray microscopy (SXM) was used investigate the behaviour of cobalt at the nanoscale in Co-Fe(III)-oxyhydroxides undergoing microbial reduction. SXM can assess spatial changes in metal speciation and organic compounds helping to elucidate the electron transfer processes occurring at the cell-mineral interface and inform on the fate of cobalt in redox horizons. G. sulfurreducens was used to reduce synthetic Co-ferrihydrite as an analogue of natural cobalt-iron-oxides. Magnetite [Fe(II)/Fe(III)3O4] production was confirmed by powder X-ray diffraction (XRD), SXM and X-ray magnetic circular dichroism (XMCD) data, where best fits of the latter suggested Co-bearing magnetite. Macro-scale XAS techniques suggested Co(III) reduction occurred and complementary SXM at the nanoscale, coupled with imaging, found localised biogenic Co(III) reduction at the cell-mineral interface via direct contact with outer membrane cytochromes. No discernible localised changes in Fe speciation were detected in the reordered cobalt-iron-oxides that were formed and at the end point of the experiment only 11% Co and 1.5% Fe had been solubilised. The solid phase retention, alongside the highly localised and preferential cobalt bioreduction observed at the nanoscale is consistent with retention of Co in redox zones. This work improves our fundamental molecular-scale understanding of the fate of Co in complex environmental systems and supports the development of biogenic Co-doped magnetite for industrial applications from drug delivery systems to magnetic recording media.
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May 2022
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I08-Scanning X-ray Microscopy beamline (SXM)
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A.
Steele
,
L. G
Benning
,
R.
Writh
,
A.
Schreiber
,
T.
Araki
,
F. M.
Mccubbin
,
M. R.
Fries
,
L. R.
Nittler
,
J.
Wang
,
L. J.
Hallis
,
P. G.
Conrad
,
C.
Conley
,
S.
Vitale
,
A. C.
O'Brien
,
V.
Riggi
,
K.
Rogers
Diamond Proposal Number(s):
[2444]
Abstract: Water-rock interactions are relevant to planetary habitability, influencing mineralogical diversity and the production of organic molecules. We examine carbonates and silicates in the martian meteorite Allan Hills 84001 (ALH 84001), using colocated nanoscale analyses, to characterize the nature of water-rock reactions on early Mars. We find complex refractory organic material associated with mineral assemblages that formed by mineral carbonation and serpentinization reactions. The organic molecules are colocated with nanophase magnetite; both formed in situ during water-rock interactions on Mars. Two potentially distinct mechanisms of abiotic organic synthesis operated on early Mars during the late Noachian period (3.9 to 4.1 billion years ago).
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Jan 2022
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I08-Scanning X-ray Microscopy beamline (SXM)
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Giovanni
De Giudici
,
Carlo
Meneghini
,
Carla
Buosi
,
Ilaria
Carlomagno
,
Giuliana
Aquilanti
,
Tohru
Araki
,
Diana E.
Bedolla
,
Maria Antonietta
Casu
,
Antonietta
Cherchi
,
Alessandra
Gianoncelli
,
Antonella
Iadecola
,
Andrei C.
Kuncser
,
V. Adrian
Maraloiu
,
Olivier
Mathon
,
Valentina
Rimondi
,
Pierpaolo
Zuddas
,
Daniela
Medas
Diamond Proposal Number(s):
[16496]
Abstract: Biominerals are widespread in Nature and they precipitate to respond to different physiological purposes. A broad knowledge of their chemical and structural properties offers a unique opportunity to improve our capability to reconstruct actual and paleoenvironment. In this work, we show two case studies, bivalves and foraminifera grown in polluted sites that were characterized by applying different and complementary synchrotron radiation-based investigation techniques, mainly focused on the investigation of Zn incorporation in the biomineralized shells. Using scanning transmission X-ray microscopy (STXM) and X-ray micro-fluorescence (µ-XRF), we found the colocalization of elements across the shells, while we obtained information on chemical speciation of Zn by applying X-ray absorption spectroscopy (XAS). Noticeably, instead of metal dispersion in the Ca-carbonate shells, we found traces of several independent phases, in particular for Zn, dispersed generally as microscopic minerals. This work provides fundamental insight into the structural properties, coordinative and chemical environment of some marine biominerals. This new knowledge is fundamental to understand the biogeochemical processes and to develop effective environmental proxies.
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May 2021
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I08-Scanning X-ray Microscopy beamline (SXM)
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Diamond Proposal Number(s):
[20900]
Open Access
Abstract: We report on the detection of primordial organic matter within the carbonaceous chondrite Maribo that is distinct from the majority of organics found in extraterrestrial samples. We have applied high-spatial resolution techniques to obtain C-N isotopic compositions, chemical, and structural information of this material. The organic matter is depleted in 15N relative to the terrestrial value at around δ15N ~ -200‰, close to compositions in the local interstellar medium. Morphological investigations by electron microscopy revealed that the material consists of µm- to sub-µm-sized diffuse particles dispersed within the meteorite matrix. Electron energy loss and synchrotron X-ray absorption near-edge structure spectroscopies show that the carbon functional chemistry is dominated by aromatic and C=O bonding environments similar to primordial organics from other carbonaceous chondrites. The nitrogen functional chemistry is characterized by C-N double and triple bonding environments distinct from what is usually found in 15N-enriched organics from aqueously altered carbonaceous chondrites. Our investigations demonstrate that Maribo represents one of the least altered CM chondrite breccias found to date and contains primordial organic matter, probably originating in the interstellar medium.
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Nov 2020
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I08-Scanning X-ray Microscopy beamline (SXM)
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Open Access
Abstract: This study explores the delivery of phosphorus to the upper atmospheres of Earth, Mars, and Venus via the ablation of cosmic dust particles. Micron-size meteoritic particles were flash heated to temperatures as high as 2900 K in a Meteor Ablation Simulator (MASI), and the ablation of PO and Ca recorded simultaneously by laser induced fluorescence. Apatite grains were also ablated as a reference. The speciation of P in anhydrous chondritic porous Interplanetary Dust Particles was made by K-edge X-ray absorption near edge structure (XANES) spectroscopy, demonstrating that P mainly occurs in phosphate-like domains. A thermodynamic model of P in a silicate melt was then developed for inclusion in the Leeds Chemical Ablation Model (CABMOD). A Regular Solution model used to describe the distribution of P between molten stainless steel and a multicomponent slag is shown to provide the most accurate solution for a chondritic-composition, and reproduces satisfactorily the PO ablation profiles observed in the MASI. Meteoritic P is moderately volatile and ablates before refractory metals such as Ca; its ablation efficiency in the upper atmosphere is similar to Ni and Fe. The speciation of evaporated P depends significantly on the oxygen fugacity, and P should mainly be injected into planetary upper atmospheres as PO2, which will then likely undergo dissociation to PO (and possibly P) through hyperthermal collisions with air molecules. The global P ablation rates are estimated to be 0.017 t d−1 (tonnes per Earth day), 1.15 × 10−3 t d−1 and 0.024 t d−1 for Earth, Mars and Venus, respectively.
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Apr 2020
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B22-Multimode InfraRed imaging And Microspectroscopy
I08-Scanning X-ray Microscopy beamline (SXM)
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Diamond Proposal Number(s):
[15050, 14953]
Open Access
Abstract: Precambrian fossils of fungi are sparse, and the knowledge of their early evolution and the role they played in the colonization of land surface are limited. Here, we report the discovery of fungi fossils in a 810 to 715 million year old dolomitic shale from the Mbuji-Mayi Supergroup, Democratic Republic of Congo. Syngenetically preserved in a transitional, subaerially exposed paleoenvironment, these carbonaceous filaments of ~5 μm in width exhibit low-frequency septation (pseudosepta) and high-angle branching that can form dense interconnected mycelium-like structures. Using an array of microscopic (SEM, TEM, and confocal laser scanning fluorescence microscopy) and spectroscopic techniques (Raman, FTIR, and XANES), we demonstrated the presence of vestigial chitin in these fossil filaments and document the eukaryotic nature of their precursor. Based on those combined evidences, these fossil filaments and mycelium-like structures are identified as remnants of fungal networks and represent the oldest, molecularly identified remains of Fungi.
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Jan 2020
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I08-Scanning X-ray Microscopy beamline (SXM)
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Alastair J. M.
Lough
,
Douglas P.
Connelly
,
William B.
Homoky
,
Jeffrey A.
Hawkes
,
Valerie
Chavagnac
,
Alain
Castillo
,
Majid
Kazemian
,
Ko-Ichi
Nakamura
,
Tohru
Araki
,
Burkhard
Kaulich
,
Rachel A.
Mills
Diamond Proposal Number(s):
[12738]
Open Access
Abstract: Iron (Fe) limits primary productivity and nitrogen fixation in large regions of the world’s oceans. Hydrothermal supply of Fe to the global deep ocean is extensive; however, most of the previous work has focused on examining high temperature, acidic, focused flow on ridge axes that create “black smoker” plumes. The contribution of other types of venting to the global ocean Fe cycle has received little attention. To thoroughly understand hydrothermal Fe sources to the ocean, different types of vent site must be compared. To examine the role of more diffuse, higher pH sources of venting, a hydrothermal plume above the Von Damm vent field (VDVF) was sampled for Total dissolvable Fe (unfiltered, TDFe), dissolved Fe (<0.2 μm, dFe) and soluble Fe (<0.02 μm, sFe). Plume particles sampled in situ were characterized using scanning electron microscopy and soft X-ray spectromicroscopy. The VDVF vents emit visibly clear fluids with particulate Fe (TDFe-dFe, >0.2 μm) concentrations up to 196 nmol kg–1 comparable to concentrations measured in black smoker plumes on the Mid-Atlantic Ridge. Colloidal Fe (cFe) and sFe increased as a fraction of TDFe with decreasing TDFe concentration. This increase in the percentage of sFe and cFe within the plume cannot be explained by settling of particulates or mixing with background seawater. The creation of new cFe and sFe within the plume from the breakdown of pFe is required to close the Fe budget. We suggest that the proportional increase in cFe and sFe reflects the entrainment, breakdown and recycling of Fe bearing organic particulates near the vents. Fe plume profiles from the VDVF differ significantly from previous studies of “black smoker” vents where formation of new pFe in the plume decreases the amount of cFe. Formation and removal of Fe-rich colloids and particles will control the amount and physico-chemical composition of dFe supplied to the deep ocean from hydrothermal systems. This study highlights the differences in the stabilization of hydrothermal Fe from an off-axis diffuse source compared to black smokers. Off-axis diffuse venting represent a potentially significant and previously overlooked Fe source to the ocean due to the difficulties in detecting and locating such sites.
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Jul 2019
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I08-Scanning X-ray Microscopy beamline (SXM)
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Abstract: Primitive CO3 carbonaceous chondrite meteorites provide a detailed record of the geological processes and events that have shaped our solar system over the last 4.5 billion years. They contain a fine-grained (≤ 1 μm) matrix (> 50 vol%) of amorphous and crystalline silicates, oxides, sulphides and metals that have remained largely unaltered since the time they accreted into an asteroid. The matrix of CO3 carbonaceous chondrites also contains ~5 wt% carbon in a wide variety of organic materials including soluble molecules, kerogen-like insoluble organic matter (IOM), and carbonaceous nanoglobules. The formation and evolution of the organic materials and their relationship to the mineralogy remains poorly understood mainly because of the fine-grained and heterogeneous nature of the matrix. However, new analytical techniques are now making it possible to study the relationship between organics and minerals in extra-terrestrial materials in-situ at high spatial resolution. Here, we present C K-edge X-ray absorption near edge structure (XANES) analyses of carbonaceous phases in the CO chondrites DOM 08006, NWA 7892 and Moss.
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Dec 2018
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I08-Scanning X-ray Microscopy beamline (SXM)
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Daniela
Medas
,
Ilaria
Carlomagno
,
Carlo
Meneghini
,
Giuliana
Aquilanti
,
Tohru
Araki
,
Diana
Bedolla
,
Carla
Buosi
,
Maria Antonietta
Casu
,
Alessandra
Gianoncelli
,
Andrei C.
Kuncser
,
V. Adrian
Maraloiu
,
Giovanni
De Giudici
Diamond Proposal Number(s):
[16496]
Abstract: Zinc incorporation into marine bivalve shells belonging to different genera (Donax, Glycymeris, Lentidium, and Chamelea) grown in mine-polluted seabed sediments (Zn up to 1% w/w) was investigated using x-ray diffraction (XRD), chemical analysis, soft x-ray microscopy combined with low-energy x-ray fluorescence (XRF) mapping, x-ray absorption spectroscopy (XAS), and transmission electron microscopy (TEM). These bivalves grew their shells, producing aragonite as the main biomineral and they were able to incorporate up to 2.0–80 mg/kg of Zn, 5.4–60 mg/kg of Fe and 0.5–4.5 mg/kg of Mn. X-ray absorption near edge structure (XANES) analysis revealed that for all the investigated genera, Zn occurred as independent Zn mineral phases, i.e., it was not incorporated or adsorbed into the aragonitic lattice. Overall, our results indicated that Zn coordination environment depends on the amount of incorporated Zn. Zn phosphate was the most abundant species in Donax and Lentidium genera, whereas, Chamelea shells, characterized by the highest Zn concentrations, showed the prevalence of Zn-cysteine species (up to 56% of total speciation). Other Zn coordination species found in the investigated samples were Zn hydrate carbonate (hydrozincite) and Zn phosphate. On the basis of the coordination environments, it was deduced that bivalves have developed different biogeochemical mechanisms to regulate Zn content and its chemical speciation and that cysteine plays an important role as an active part of detoxification mechanism. This work represents a step forward for understanding bivalve biomineralization and its significance for environmental monitoring and paleoreconstruction.
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Oct 2018
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I08-Scanning X-ray Microscopy beamline (SXM)
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Abstract: Fluoroacetate (FA), a plant toxin and intermediate product of anticancer agents, integrates itself into the Krebs cycle by substituting for acetate to form fluorocitrate. The function of this key metabolic cycle in glucose metabolism is disabled when fluorocitrate binds to aconitase. FA purportedly disrupts the Krebs cycle selectively in non-neuronal cells, i.e. glia/astrocytes, making it the substance of choice by which to assess the importance of glia for brain function in the living animal. However, since acetate, considered a marker of glial oxidative metabolism, can also be transported into neurons begs the question whether FA uptake, metabolism, and compartmentation is glial-selective in vivo, and whether this can be experimentally imaged; as important, is whether the first phase of brain glucose metabolism, i.e. glycolysis is affected. Dynamic cerebral 18FDG (glucose) PET in the living rat, and low energy x-ray fluorescence chemical imaging of such brains, albeit freeze substitution-fixed and epon infiltrated, were implemented to address these questions, and enabled testing our working hypothesis that sexual dimorphism of brain structure and function extends to metabolism as well.
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Aug 2018
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