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The organic interprismatic layers of the mollusc Pinctada margaritifera are studied using a variety of highly spatially-resolved techniques to establish their composition and structure. Our results show that both the interlamellar sheets of the nacre and interprismatic envelopes form layered structures. Additionally, these organic layers are neither homogeneous in composition, nor continuous in their structure. Both structures play a major role in the biomineralization process and act as a boundary between mineral units. [ABSTRACT FROM AUTHOR]

To investigate the potential of synchrotron-based X-ray Absorption Near-Edge Structure spectroscopy (XANES) at the sulphur (S) K-edge for a discrimination of adsorbed and precipitated sulphate in soils and soil particles, XANES spectra of ionic sulphate compounds and Al/Fe hydroxy sulphate minerals were compared with spectra of SO42− adsorbed to ferrihydrite, goethite, haematite, gibbsite or allophane. Ionic sulphate and hydroxy sulphate precipitates had broader white-lines (WL) at 2482.5 eV (full width at half maximum (FWHM) of edge-normalized spectra, 2.4–4.2 eV; Al hydroxy sulphates, 3.0 eV) than SO42− adsorbed to Al/Fe oxyhydroxides or allophane (FWHM, 1.8–2.4 eV). The ratio of the white-line (WL) height to the height of the post-edge feature at 2499 eV (WL/PEF) was larger for SO42− adsorbed to Al/Fe oxyhydroxides or allophane (8.1–11.9) than for Al/Fe hydroxy sulphates and ionic sulphates (3.9–5.7). The WL/PEF ratio of edge-normalized S K-edge XANES spectra can be used to distinguish adsorbed from precipitated SO42− in soils and also at microsites of soil particles. The contribution of adsorbed and precipitated SO42− to the total SO42− pool can be roughly quantified. Adsorbed ester sulphate may result in overestimation of precipitated SO42−. The spectra of most soils could be fitted by linear combination fitting (LCF), yielding a similar partitioning between adsorbed and precipitated SO42− as an evaluation of the WL/PEF ratio. The SO42− pool of German forest soils on silicate parent material in most cases was strongly dominated by adsorbed SO42−; however, in three German forest soils subject to elevated atmospheric S deposition, a considerable portion of the SO42− pool was precipitated SO42−, most likely Al hydroxy sulphate. The same is true for Nicaraguan Eutric and Vitric Andosols subject to high volcanogenic S input. In the subsoil of the Vitric Andosol, adsorbed SO42− and Al hydroxy sulphate coexist on a micron scale. [ABSTRACT FROM AUTHOR]

Microorganisms were searched for among the complex microstructures observed on the surface of a fragment of the Tatahouine meteorite inherited from the Tunisian soil in which they were buried. In this view, the chemical compositions, particularly the nitrogen, phosphorus, and sulphur compositions, including the sulphur speciation, were investigated using scanning electron microscopy (SEM), electron probe microanalysis (EPMA) mapping, and scanning X-ray microscopy (SXM). A few 2-μm-thick filaments, partly covered by patches of calcite ensuring they were not deposited by a laboratory contamination, were observed by SEM. The EPMA maps show that the portions free of calcite of the filaments have low but constant contents of nitrogen, sulphur, and phosphorus. The SXM maps were recorded at 2473.5, 2478, and 2482.2 eV, which are respectively characteristic for amino acid linked sulphur, sulphite (SO32−), and sulphate (SO42−). The portions of the filaments detected by EPMA are also those that are enriched in amino acid linked sulphur. The calculated (N/S) elemental ratio is consistent with the one of the dehydrated Escherichia coli matter, contrary to the much lower (P/S) elemental ratio. In living cells, the bulk N and S elements are mainly located in large polymers by covalent bonds, whereas a significant amount of P belongs to small and reactive molecules. We thus can propose that the observed microstructures are dehydrated microorganisms, in which most of the elements that were composing the polymers were retained, whereas the small electrolytes and molecules were removed. [Copyright &y& Elsevier]

The role of the Toll-like receptor (TLR)-2 in the generation of protective immunity to Mycobacterium avium was evaluated using gene-disrupted mice. TLR-2−/− mice were more susceptible than wild-type C57Bl/6 mice to M. avium strains that were able to proliferate in vivo before the development of protective immunity and mycobacteriostasis. In contrast, the elimination of non-virulent strains was not affected by the mutation. The generation of interferon-γ (IFN-γ)-producing T cells and the expression of the interleukin-12 p40 gene were reduced in TLR-2-deficient mice as compared to C57Bl/6 mice early during infection with M. avium strain 2447. The generation of protective CD4+ T cells was also compromised in the mutated mice as compared with the controls. Our data show that TLR-2 is required for optimal immunity against certain virulent M. avium strains. [ABSTRACT FROM AUTHOR]

The host cells from endomycorrhizas of Ophrys lutea Cav, contain many coated vesicles associated with dictyosomes, with a membrane system (probably partially coated reticulum) and with the host's sequestration plasmalemma. The contents of coated vesicles stain with neither the PATAg test for polysaccharides nor with ruthenium red. The involvement of coated vesicles in the host/endophyte interactions during the establishment of O. lutea endomycorrhizas is discussed. [ABSTRACT FROM AUTHOR]

In this work we report the successful assembly and characterization of a TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber solar cell. Nanostructured TiO2 deposited by screen printing on an ITO substrate was used as an n-type electrode. An ∼80 nm extremely thin layer of the system In2S3-Sb2S3 deposited by successive ionic layer adsorption and a reaction (silar) method was used as an absorber. The voids were filled with p-type CuSCN and the entire assembly was completed with a gold contact. The solar cell fabricated with this heterostructure showed an energy conversion efficiency of 4.9%, which is a promising result in the development of low cost and simple fabrication of solar cells. [ABSTRACT FROM AUTHOR]

This work shows a promising N-doped carbon catalyst for the oxidation of oxalic acid by catalytic wet oxidation, which is able to compete with the traditional noble metal and metal oxide catalysts used in the process. After preliminary studies conducted in batch mode, the catalytic performance of the metal-free carbon nanotubes, both in powder form and supported on a macrostructured carrier (a cordierite monolith), was evaluated under continuous operating conditions. The ability of the N-functionalities to promote activation and chemisorption of oxygen led not only to fast oxalic acid mineralization under batch mode (5 min of reaction to reach full mineralization), but also to good performance under continuous operation (more than 90% conversion of oxalic acid in the steady state, using the powder and around 55% using the catalyst immobilized on a honeycomb cordierite monolith). [ABSTRACT FROM AUTHOR]

To reduce the environmental impacts from sodium silicate synthesis, a ceramic method was suggested, with sugarcane bagasse ash (SCBA) as the source of silicon dioxide and sodium carbonate. Although the production of sodium silicate is carried out on a large scale, it should be noted that its process requires temperatures above 1000 °C; it also requires the use of highly corrosive agents such as sodium hydroxide and chlorine gas to neutralize the remaining sodium hydroxide. In the present study, the synthesis temperatures were reduced to 800 °C with a reaction time of 3 h by pressing equimolar mixtures of previously purified SCBA and sodium carbonate; then, heat treatment was carried out under the indicated conditions. The resulting materials were analyzed with Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Among the crystalline phases, calcium disodium silicate was identified, in addition to sodium silicate; thus, it was inferred that the other components of the ash can interfere with the synthesis of silicate. Therefore, in order to obtain the highest composition of sodium silicate, a leaching treatment of the SCBA is required. [ABSTRACT FROM AUTHOR]

Sensitization of nanoporous TiO 2 with Sb 2 S 3 , Bi 2 S 3 , and In 2 S 3 thin films deposited at the room temperature by using the simple and inexpensive SILAR method is presented. Structural, morphological, and optical characterization of thin films prepared by this method were conducted by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS). The photocurrent response of the thin films was studied with a three electrode photoelectrochemical cell. The influence of the number of deposition cycles on the optical properties of the thin films was investigated, and the structural and morphological studies revealed the formation of polycrystalline thin films with an orthorhombic structure for Sb 2 S 3 and Bi 2 S 3 system, whereas a cubic structure was found for the In 2 S 3 , which had a cluster-like surface morphology and uniform distribution. Optical studies showed that enhancing TiO 2 light absorption in the visible range is possible by the incorporation of antimony, bismuth, and indium sulfides. Photocurrent measurements showed that photons are absorbed by metal sulfide and electrons injected to TiO 2 . [ABSTRACT FROM AUTHOR]

Abstract: Very little is known about the sub-cellular distribution of metal ions in cells. Some metals such as zinc, copper and iron are essential and play an important role in the cell metabolism. Dysfunctions in this delicate housekeeping may be at the origin of major diseases. There is also a prevalent use of metals in a wide range of diagnostic agents and drugs for the diagnosis or treatment of a variety of disorders. This is becoming more and more of a concern in the field of nanomedicine with the increasing development and use of nanoparticles, which are suspected of causing adverse effects on cells and organ tissues. Synchrotron-based X-ray and Fourier-transformed infrared microspectroscopies are developing into well-suited sub-micrometer analytical tools for addressing new problems when studying the role of metals in biology. As a complementary tool to optical and electron microscopes, developments and studies have demonstrated the unique capabilities of multi-keV microscopy: namely, an ultra-low detection limit, large penetration depth, chemical sensitivity and three-dimensional imaging capabilities. More recently, the capabilities have been extended towards sub-100nm lateral resolutions, thus enabling sub-cellular chemical imaging. Possibilities offered by these techniques in the biomedical field are described through examples of applications performed at the ESRF synchrotron-based microspectroscopy platform (ID21 and ID22 beamlines). [Copyright &y& Elsevier]

In the present research, self-supported hierarchical nanocomposites of Ni3Se2/Ni(OH)2/Ni and Ni3Se2/Ni were developed and their performance as a hydrogen evolution reaction (HER) catalyst for alkaline electrolytic water splitting was demonstrated. The composite Ni3Se2/Ni(OH)2/Ni was obtained through a hydrothermal process and subsequent selenization reaction by heat treatment, while the Ni3Se2/Ni was synthesized only through a selenization reaction by heat treatment. The materials were characterized by confocal microscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy. The results that displayed different structures were grown on the Ni-foam, such as Ni(OH)2 nanoleaflets, Ni3Se2 nanosticks composed of spheres, and Ni3Se2 nanowires between Ni(OH)2 nanoleaflets, for Ni(OH)2/Ni, Ni3Se2/Ni, and Ni3Se2/Ni(OH)2/Ni composites, respectively. The catalysts exhibited an excellent hydrogen evolution reaction activity with overpotentials of 170.0 and 194.8 mV at a current density of 10 mA cm−2, with a Tafel slope of 123.5 and 127.3 mV decade−1 for Ni3Se2/Ni and Ni3Se2/Ni(OH)2/Ni, respectively. Graphical abstract [ABSTRACT FROM AUTHOR]

In this paper, we develop a methodological approach combining macro-X-ray fluorescence and synchrotron radiation-based techniques (μXRF, full-field XANES and μXRD) to determine the composition and microstructure of underglaze decors of Qinghua porcelains (Ming dynasty). Various transition metal elements (Fe, Mn, Co) are present in the blue decoration of these ceramics and the approach proposed allows for establishing the feature of each. Thus it shows that Fe ions are distributed homogeneously over the whole glaze without any significant difference in blue and white parts. They do not play a significant role in the color. In contrast, Co ions exhibit a heterogeneous distribution with CoAl 2 O 4 particles close to the body/glaze interphase. These particles play a key role in the blue color and, the hue variations seem in greater part to link to their density and repartition. Co dispersed in the glassy matrix is also bivalent and mainly in tetragonal coordination, leading also to a blue color. Mn ion distribution is similar to the one of Co but without presenting local high concentrations associated to Mn based particles. Mn affects the darkness of the color and for the sample without CoAl 2 O 4 particle; it is the main color contribution. The presence of CoAl 2 O 4 crystals was confirmed by μXRD, which revealed, in addition, a variation of cell parameters certainly linking to a Co partial substitution. [ABSTRACT FROM AUTHOR]

The chemical and physical alterations of cadmium yellow (CdS) paints in Henri Matisse's The Joy of Life (1905-1906, The Barnes Foundation) have been recognized since 2006, when a survey by portable X-ray fluorescence identified this pigment in all altered regions of the monumental painting. This alteration is visible as fading, discoloration, chalking, flaking, and spalling of several regions of light to medium yellow paint. Since that time, synchrotron radiation-based techniques including elemental and spectroscopic imaging, as well as X-ray scattering have been employed to locate and identify the alteration products observed in this and related works by Henri Matisse. This information is necessary to formulate one or multiple mechanisms for degradation of Matisse's paints from this period, and thus ensure proper environmental conditions for the storage and the display of his works. This paper focuses on 2D full-field X-ray Near Edge Structure imaging, 2D micro-X-ray Diffraction, X-ray Fluorescence, and Fourier Transform Infra-red imaging of the altered paint layers to address one of the long-standing questions about cadmium yellow alteration-the roles of cadmium carbonates and cadmium sulphates found in the altered paint layers. These compounds have often been assumed to be photo-oxidation products, but could also be residual starting reagents from an indirect wet process synthesis of CdS. The data presented here allow identifying and mapping the location of cadmium carbonates, cadmium chlorides, cadmium oxalates, cadmium sulphates, and cadmium sulphides in thin sections of altered cadmium yellow paints from The Joy of Life and Matisse's Flower Piece (1906, The Barnes Foundation). Distribution of various cadmium compounds confirms that cadmium carbonates and sulphates are photo-degradation products in The Joy of Life, whereas in Flower Piece, cadmium carbonates appear to have been a [(partially) unreacted] starting reagent for the yellow paint, a role previously suggested in other altered yellow paints. [ABSTRACT FROM AUTHOR]

Abstract: Total reflection X-ray fluorescence (TXRF) and grazing emission X-ray fluorescence (GEXRF) are surface sensitive techniques and can be used for detailed surface studies of different materials, including ultra-low concentration contamination or the lateral and depth distributions of elements. The calibration procedure typically used involves placing a micro-droplet of the standard solution onto a silicon wafer (or quartz backing). After evaporation of the solvent, the residual amount of elements is used as a reference standard. Knowledge of the distribution of residue material on the substrate surface is crucial for precise quantification. In the present work the investigation of the lateral distribution of elements in the multielemental calibrating samples, containing the 23 most commonly studied elements, by using the synchrotron radiation based micro X-ray fluorescence is presented. The goal of this project was the study of a uniformity of the elemental distributions and determination of the residual elements morphology depending on the temperature of the drying process. The X-ray images were compared with optical and SEM images. Paper presents in details the experimental setup, sample preparation procedures, measurements and results. In the analysis of the X-ray images of the sample dried in high temperature the censoring approach was applied improving the quality of statistical analysis. The information on the elements distribution in the calibrating samples can be useful for developing more accurate calibration procedures applied in quantitative analysis of surface sensitive TXRF and GEXRF techniques. [Copyright &y& Elsevier]

In this study, the local atomic structure of highly homogeneous Ga1-xMnxN alloy films (0.03

The microstructure and composition, including chemical speciation of sulphur (S), of two mollusc shells were investigated using a combination of scanning electron microscopy, X-ray absorption near-edge structure spectroscopy (XANES) and electron probe microanalysis (EPMA). The shell of Pinna is composed of monocrystalline, and Pinctada, of polycrystalline, calcite prisms separated by organic-rich walls. Sulphur speciation information from XANES spectra using a scanning X-ray microscope showed that the protein S content of the interprismatic walls is higher than the SO4 content, whereas the reverse is true for the intraprismatic structures. High-spatial-resolution XANES maps for the different S species across adjacent calcite prisms confirm their distinctive distributions in the molluscan shells and illustrate the presence of narrow, submicron transverse growth features. On a larger scale, a series of wider growth zones, incorporating the submicron zones, are aligned parallel to each other and cross-cut many calcite prisms. EPMA element maps for magnesium (Mg) and S demonstrate that these growth increments are compositionally zoned, comprising alternating layers of high mineral (Mg-rich) and high organic (S-rich) components. Additionally, these maps confirm that the organic interprismatic walls have lower Mg and higher S than the intraprismatic structures. [ABSTRACT FROM AUTHOR]

New information about calcium status in human scalp hair shaft, deduced from X-ray micro-fluorescence imaging, including its distribution over the hair section, the existence of one or several binding-types and its variation between people, is presented. The existence of two different calcium types is inferred. The first one corresponds to atoms (or ions) easily removable by hydrochloric acid, located in the cortex (granules), in the cuticle zone and also in the core of the medulla, which can reasonably be identified as calcium soaps. The second type consists of non-easily removable calcium atoms (or ions) that are located in the medulla wall, probably also in the cuticle, and rather uniformly in the cortex; these calcium atoms may be involved in Ca2+-binding proteins, and their concentration is fairly constant from one subject to another. In addition to its nonuniform distribution across the hair section, the second striking feature of the first type calcium content is its high variability from one subject to another, by up to a factor 10. We expect this information to be useful for analyzing in more detail the relationship between hair calcium and environmental and medical factors. [Copyright &y& Elsevier]