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Identification of chemical species at a subcellular level is a key to understand the mechanisms involved in the biology of chemical elements. When performed with a microbeam, X-ray absorption near-edge structure (micro-XANES) enables the direct speciation analysis of oxidation states in subcellular compartments avoiding cell fractionation and other preparation steps that might modify the chemical species. Here we report the principal characteristics in terms of spatial resolution, detection limit, reproducibility, and repeatability of a micro-XANES experimental setup based on Kirkpatrick--Baez X-ray focusing optics that maintains high flux of incoming radiation (> [10.sup.11] photons/s) at micrometric spatial resolution (1.5 x 4.0 [micro][m.sup.2]). Applications and limitations of this setup are illustrated by examples of iron and arsenic absorption spectra obtained from the cytosol, nucleus, and mito-chondrial network of cultured cells. A better repeatability and sensitivity with no oxidation state modification and minimal beam damage is achieved when cells are analyzed in a frozen hydrated state, as compared to freeze-dried cells. This original experimental setup can now be applied for the direct speciation analysis of most trace elements at the subcellular level.

Trace element imaging and speciation analysis in cells and subcellular compartments is a challenging and important objective for modern analytical chemistry in order to better understand the biological chemistry of essential and toxic elements. A focusing system based on Kirkpatrick--Baez design optics mounted on a synchrotron radiation scanning X-ray microscope has been developed at the ESRF and was used for trace element quantitative imaging in single cells. The focused microbeam (1.3 x 3.2 [micro][m.sup.2]) obtained in that way led to a photon flux as bright as 1.5 x [10.sup.11] photons/s at 14 keV. The absolute detection limit of this analytical probe, as measured on standard reference materials, was shown to be 2 x [10.sup.-17] g for most elements. Chemical maps of human carcinoma and of Saccharomyces cerevisiae cells were obtained for minor (P, S, Cl, K) and trace elements (Fe, Zn). Within human cancer cells, chemical elements are homogeneously distributed at the current spatial resolution and correlated with the sample's mass, except Fe, which shows micrometer-sized structures around the cell nucleus, and Zn, which slightly concentrates in the nucleus, while chemical maps of S. cerevisiae show homogeneous pattern distribution at the cellular level.

The propagation of a high amplitude surface acoustic wave in an Al thin film induces a large-scale electromigration activity resulting in a permanent etching of the acoustic field in the film. The etch patterns depend on the time of propagation and on the acoustic characteristics. Preliminary observations were conducted on a few grooved structures in Al films by various methods. A first explanation of this phenomenon based on dynamical Grinfeld instabilities is presented.

Redox processes activated by environmental factors have been identified as the main cause of the chromatic alterations of a number of artists' pigments, including the yellow pigment orpiment (As2S3). Although a general comprehension of the mechanisms has been provided through characterization of degradation compounds of As2S3, experimental evidences to prove how other paint components and how different environmental agents influence the formation pathways of specific secondary compounds are still lacking. Thus, it becomes fundamental to develop a methodological strategy which enable achieving a discrimination among the causes affecting the chemical stability of more heterogenous As2S3-based paints and defining the mechanism through which the alteration establishes and evolves, with the ultimate goal of optimizing the preventive conservation measures of unique masterpieces. In this paper, we propose a comprehensive multi-material and multi-method approach based on the combination of synchrotron radiation X-ray micro-analytical techniques (i.e., X-ray diffraction, X-ray fluorescence and X-ray absorption near edge structure spectroscopy at S K-/Ag L3-/As K-edges) and vibrational micro-spectroscopy methods to unveil the causes and mechanism of darkening of "fake-gilded" decorations in tempera paintings, originally consisting of an unusual mixture of As2S3 and metallic silver (Ag0). Such degradation process is a not yet understood phenomenon threatening a series of Old Master paintings, including those by the Italian painters Cimabue and Pietro Lorenzetti. The high specificity, sensitivity and lateral resolution of the employed analytical methods allowed providing first-time evidence for the presence of black acanthite (α-Ag2S), mimetite [Pb5(AsO4)3Cl] and syngenite [K2Ca(SO4)2·H2O] as degradation products of the "fake-gilded" decorations in the Maestà by Cimabue (Church of Santa Maria dei Servi, Bologna, Italy). Furthermore, the study of the painting combined with that of tempera paint mock-ups permitted to explore and define the environmental agents and internal factors causing the darkening, by proving that: (i) Ag0 and moisture are key-factors for triggering the transformation of As2S3 to α-Ag2S and As-oxides; (ii) S2--ions arising from the degradation of As2S3 are the main responsible for the formation of α-Ag2S; (iii) light exposure strengthens the tendency of the paint components towards alteration. Based on our findings, we finally propose a degradation mechanism of As2S3/Ag0-based tempera paints. [ABSTRACT FROM AUTHOR]

Theoretical and experimental studies of the space-time modulation of an X-ray beam in an ultrasonic superlattice by determining the total external reflection demonstrate the feasibility of construction of space-time modulated X-ray optical elements. Wavelength and amplitude of the surface acoustic waves (SAWS) control the X-ray diffraction. X-ray diffraction is also suitable for diagnostics of SAW devices.

Metallic implants are frequently used in medicine to support and replace degenerated tissues. Implant loosening due to particle exposure remains a major cause for revision arthroplasty. The exact role of metal debris in sterile peri‐implant inflammation is controversial, as it remains unclear whether and how metals chemically alter and potentially accumulate behind an insulating peri‐implant membrane, in the adjacent bone and bone marrow (BM). An intensively focused and bright synchrotron X‐ray beam allows for spatially resolving the multi‐elemental composition of peri‐implant tissues from patients undergoing revision surgery. In peri‐implant BM, particulate cobalt (Co) is exclusively co‐localized with chromium (Cr), non‐particulate Cr accumulates in the BM matrix. Particles consisting of Co and Cr contain less Co than bulk alloy, which indicates a pronounced dissolution capacity. Particulate titanium (Ti) is abundant in the BM and analyzed Ti nanoparticles predominantly consist of titanium dioxide in the anatase crystal phase. Co and Cr but not Ti integrate into peri‐implant bone trabeculae. The characteristic of Cr to accumulate in the intertrabecular matrix and trabecular bone is reproducible in a human 3D in vitro model. This study illustrates the importance of updating the view on long‐term consequences of biomaterial usage and reveals toxicokinetics within highly sensitive organs. [ABSTRACT FROM AUTHOR]

A helium mini‐cryostat has been developed for the hard X‐ray nanoprobe ID16B of the European Synchrotron to collect X‐ray excited optical luminescence and X‐ray fluorescence at low temperature (<10 K). The mini‐cryostat has been specifically designed to fit within the strong space restrictions and high‐demanding mechanical constraints imposed by the beamline to provide vibration‐free operation and maximal thermal stability. This paper reports the detailed design, architecture and technical requirements of the mini‐cryostat, and presents the first experimental data measured using the cryogenic equipment. The resulting cryo‐system features ultimate thermal stability, fast cool‐down and ultra‐low vibrations. The simultaneous X‐ray fluorescence and X‐ray excited optical luminescence data acquired from bulk GaN and core/shell InGaN/GaN multi‐quantum wells validated the excellent performance of the cryostat with ultimate resolution, stability and sensitivity. [ABSTRACT FROM AUTHOR]

We present a new diamond anvil cell design, hereafter called mBX110, that combines both the advantages of a membrane and screws to generate high pressure. It enables studies at large-scale facilities for many synchrotron X-ray techniques and has the possibility to remotely control the pressure with the membrane as well as the use of the screws in the laboratory. It is fully compatible with various gas-loading systems as well as high/low temperature environments in the lab or at large scale facilities. The mBX110 possesses an opening angle of 85° suitable for single-crystal diffraction or Brillouin spectroscopy and a large side opening of 110° which can be used for X-ray inelastic techniques, such as X-ray Raman scattering spectroscopy, but also for X-ray emission, X-ray fluorescence, or X-ray absorption. An even larger opening of 150° can be manufactured enabling X-ray imaging tomography. We report data obtained with the mBX110 on different beamlines with single-crystal diffraction of stishovite up to 55 GPa, X-ray powder diffraction of rutile-GeO2 and tungsten to 25 GPa and 280 GPa, respectively, X-Ray Raman spectra of the Si L-edge in silica to 95 GPa, and Fe Kβ X-ray emission spectra on a basalt glass to 17 GPa. [ABSTRACT FROM AUTHOR]

Synchrotron nanoprobe X-ray absorption (XAS) studies of a potent organo-osmium arene anticancer complex in ovarian cancer cells at subcellular resolution allow detection and quantification of both OsII and OsIII species, which are distributed heterogeneously in different areas of the cells. [ABSTRACT FROM AUTHOR]

Paleoceanographical reconstructions are often based on microfossil geochemical analyses. Coccoliths are the most ancient, abundant and continuous record of pelagic photic zone calcite producer organisms. Hence, they could be valuable substrates for geochemically based paleoenvironmental reconstructions but only Sr/Ca is exploited even if it remains poorly understood. For example, some murolith coccoliths species have very high Sr/Ca compared to the common 1-4 mmol/mol recorded in placolith coccoliths. In this study, we analyzed the elemental composition of the Middle Jurassic murolith Crepidolithus crassus by synchrotron-based nanoXRF (X-ray Fluorescence Spectroscopy) mapping focusing on Sr/Ca and compared the record to two placolith species, namely Watznaueria contracta and Discorhabdus striatus. In C. crassus, Sr/Ca is more than ten times higher than in both placoliths and seems higher in the proximal cycle. By comparison with the placoliths analyzed in the same analytical set-up and from the same sample, we exclude the impact of the diagenesis and seawater Sr/Ca to explain the high Sr/Ca in C. crassus. Based on comparisons to Pontosphaera discopora and Scyphosphaera apsteinii which also have high Sr/Ca, it seems more likely that high Sr/Ca in C. crassus is either due to the vertical elongation of the R-units of the proximal cycle or related to the action of the special polysaccharide controlling the growth of those vertically elongated R-units that may have affinities to Sr2+. In order to apply the Sr/Ca proxy to muroliths, further investigations are needed on cultured coccoliths.

The present work describes some new improvements concerning the analysis of cement hydration processes using `pencil-beam' synchrotron X-ray diffraction tomography. (i) A new filtering procedure, applied to the diffraction images, has been developed to separate the powder-like contribution from that of the grains in the diffraction images. (ii) In addition to improving the quality of the diffraction images for the subsequent analysis and tomographic reconstruction, the filtering procedure can also be used to perform a qualitative analysis of the crystallite size distribution, whenever the more standard approaches cannot be applied. (iii) Given the importance of the calcium silicate hydrate phase (C-S-H) in cements, a procedure to obtain its spatial distribution using the diffraction signal has been successfully applied, even though C-S-H is a highly disordered phase, almost amorphous to X-ray diffraction. (iv) The main result of this study has been to show that, in spite of the long measurement times required, it is possible to use in situ experiments at different aging times of cement pastes to monitor the cement evolution. This allowed the evolution of the microstructure during the acceleration and deceleration periods of the hydration process to be checked with unprecedented detail, since the quantitative spatial distribution of each phase (including C-S-H) dissolved or precipitated in the sample has been obtained. The reported approach opens up a range of opportunities for the investigation of complex multiphase systems and processes, including hydration and microstructural development in cements. [ABSTRACT FROM AUTHOR]

This report discusses the optimization strategy, the theoretical background and first experimental data of a new refractive lens for focusing X-rays. In order to reduce the absorption of X-rays in this transmission lens, optically passive material was removed from the necessarily concave lens shape in a highly regular pattern. The feature dimensions require lens production and replication by deep X-ray lithography, which allows shaping in only one dimension. Consequently such a lens can focus in one direction only, so a crossed lens pair is needed for two-dimensional focusing. The single lens is composed of two large prisms of millimeter size, which touch each other at one of the tips, like an old sand clock. Each large prism contains a highly regular structure of essentially identical prism-like smaller segments. The first lens prototypes focused an X-ray beam with a vertical size of 500 µm and a photon energy of 8 kev to a line with a width of only 2.8 µm. This is only slightly worse than the line width of 1.73 µm expected for its focal length of f = 2.18 m. The photon density enhancement in the focus was 25, but could have been larger as the lens can intercept a beam height of 2.6 mm. [ABSTRACT FROM AUTHOR]

The dynamical theory was used to model X-ray diffraction by the YZ-cut of an LiNbO3 crystal modulated by surface acoustic waves (SAWs). It includes both the calculation of the crystal lattice deformation, induced by a surface wave of Rayleigh type, and the simulation of X-ray wavefields in the crystal based on Takagi-Taupin equations. A detailed discussion is included on the effect of peak splitting occurring at high acoustic amplitudes. The developed theory entirely describes this effect and proves to be a powerful tool for understanding X-ray diffractometry and topography measurements by SAW-modulated crystals. [ABSTRACT FROM AUTHOR]

A hard x-ray beam of photon energy E=12.5 keV has been focused by a Kirkpatrick–Baez mirror system and coupled into the front side of a single-mode x-ray waveguide. The beam dimensions of 3.8×2.5 μm2 in the focus of the mirror system have thus been reduced in one direction to 32 nm, corresponding to the guiding layer thickness of the waveguide. At the same time the waveguide acts as a coherence filter and leads to a well-defined intensity distribution with steep tails in the near- and far-field regions. The total flux transmitted by the waveguide exceeded 108 photons/s while no significant contributions of radiation transmitted through the absorbing waveguide cladding have been observed. [ABSTRACT FROM AUTHOR]

Abstract: Zinc serves regulatory functions in cells and thus, several mechanisms exist for tight control of its homeostasis. One mechanism is storage in and retrieval from vesicles, so-called zincosomes, but the chemical speciation of zincosomal zinc has remained enigmatic. Here, we determine the intravesicular zinc-coordination in isolated zincosomes in comparison to intact RAW264.7 murine macrophage cells. In elemental maps of a cell monolayer, generated by microbeam X-ray fluorescence, zincosomes were identified as spots of high zinc accumulation. A fingerprint for the binding motif obtained by μXANES (X-ray absorption near edge structure) matches the XANES from isolated vesicles; zinc is not free, but present as a complexed form (average coordination; 1.0 sulfur, 2,5 histidines 30 and 1.0 oxygen), resembling regulatory or catalytic zinc sites in proteins. Such coordination enables reversible binding, acting as a ‘zinc sink’, facilitating the accumulation of high amounts of zinc against a concentration gradient. [Copyright &y& Elsevier]

When subjected to plastic deformation, grains within ductile face-centred cubic polycrystals fragment into “soft”, low dislocation density cells separated by “hard”, dislocation-rich walls. Using a narrow-bandwidth, sub-micrometre X-ray beam, we have mapped the deformation structure inside a single grain within a deformed Ni polycrystal. Dislocation multiplication and entanglement was found to vary depending on the physical dimensions of the grain. The method we use overcomes current limitations in classical X-ray topography allowing topographic images to be formed from small, highly deformed grains. [ABSTRACT FROM AUTHOR]