Synchrotron-Based High Angle Resolution and High Lateral Resolution X-ray Diffraction: Revealing Lead White Pigment Qualities in Old Masters Paintings.

Microsamples collected on 27 major paintings by Old European Masters dating from the 14th to the late 19th centuries were analyzed using synchrotron-based X-ray diffraction. Two complementary analytical configurations were used at beamlines ID22 (high angle resolution) and ID21 (high lateral resolution), in order to highlight markers of the different grades of the lead white pigments (mixture of cerussite PbCO3 and hydrocerussite Pb3(CO3)2(OH)2). Rietveld analysis and crystalline phases mapping at the microscale revealed the composition and microstructure of the pigments, shedding light on the preparation recipes and pigment choices of the artists through History.

Bifunctional silica nanoparticles for the exploration of biofilms of Pseudomonas aeruginosa.

Luminescent silica nanoparticles are frequently employed for biotechnology applications mainly because of their easy functionalization, photo-stability, and biocompatibility. Bifunctional silica nanoparticles (BSNPs) are described here as new efficient tools for investigating complex biological systems such as biofilms. Photoluminescence is brought about by the incorporation of a silylated ruthenium(II) complex. The surface properties of the silica particles were designed by reaction with amino-organosilanes, quaternary ammonium-organosilanes, carboxylate-organosilanes and hexamethyldisilazane. BSNPs were characterized extensively by DRIFT, (13)C and (29)Si solid state NMR, XPS, and photoluminescence. Zeta potential and contact angle measurements exhibited various surface properties (hydrophilic/hydrophobic balance and electric charge) according to the functional groups. Confocal laser scanning microscopy (CLSM) measurements showed that the spatial distribution of these nanoparticles inside a biofilm of Pseudomonas aeruginosa PAO1 depends more on their hydrophilic/hydrophobic characteristics than on their size. CLSM observations using two nanosized particles (25 and 68 nm) suggest that narrow diffusion paths exist through the extracellular polymeric substances matrix.

Synchrotron-based X-ray spectromicroscopy used for the study of an atypical micrometric pigment in 16th century paintings.

Grünewald is a famous German painter of the 16th century, whose celebrity is associated with his unique skill in handling colors. This article presents the analysis of materials used to render a metallic aspect in the Isenhein Altarpiece and the Basel's Crucifixion. Such samples are challenging objects for microanalysis due to both chemical and physical complexity. Their study by synchrotron-based X-ray microscopy techniques was made possible thanks to recent developments carried out at the ID21 beam line (European Synchrotron Radiation Facility, ESRF). A submicron X-ray fluorescence probe revealed the main presence of lead, sulfur, antimony, and calcium. The fluorescence-line interferences (in particular K-lines of sulfur with M-lines of lead, and K-lines of calcium with L-lines of antimony) were resolved with the fitting program, PyMCA. 2D-mapping highlighted the presence of micrometer grains of sulfur and antimony into a lead matrix. XANES measurements were performed at both the sulfur K-edge and the antimony L-edge to refine information from an atomic to a molecular level. Beam stability was a key point in this study to selectively probe micrometer pigment grains, dispersed in the lead matrix. They confirm that the grains are made of stibnite (antimony sulfide), a very atypical pigment. Chemical mapping of sulfides is perfectly correlated with antimony mapping and provides a clear visualization of the stibnite pigments, in addition to their identification. Besides its artistic relevancy, this work aims at illustrating developments of synchrotron X-ray microprobe methods for the chemical characterization and observation of complex and micrometer-scale materials.

Noninvasive fetal RHD genotyping from maternal plasma. Use of a new developed Free DNA Fetal Kit RhD.

Fetal RHD genotyping from maternal plasma was performed by real-time PCR amplification of exons 7 and 10 of the RHD gene and the amplified products were detected either with SYBR Green I dye according to our previously published method [Mol Diagn 8 (2004) 23-31] or with hydrolysis probes in a new Free DNA Fetal Kit RhD((R)). Plasma specimen from 300 RhD-negative pregnant women (between 10 to 34 weeks of gestation) were analysed and validation of the results was ascertained either by RHD genotyping on amniotic cells or by blood typing of the neonate at birth. We found 100% concordant results when comparing the two methods. Two false-positive but no false-negative results were found. Thus, the sensitivity of the assay was 100% and the specificity superior than 99%. These data confirm the accuracy of fetal RHD genotyping on maternal plasma using the Free DNA Fetal Kit RhD, thus allowing to propose non invasive PCR-based fetal RHD genotyping for all RhD-negative pregnant women and to restrict the use of anti-D immunoglobulins only to those bearing an RhD-positive fetus.

Triethoxysilyl-substituted aminoethanethiol ligands for zinc and cadmium complexes and aminoethanethiol-modified silica gel. Evaluation of the corresponding supported molecular trap for metallic pollutant uptake (Cd2+, Hg2+ and Pb2+).

The reaction of 2-[3-(triethoxysilyl)propylamino]ethanethiol (LH, a) and 1-methyl-2-[3-(triethoxysilyl)propylamino]ethanethiol (LH, b) with ZnX2 and CdX2 (X = Cl, Br, I, NO3) in tetrahydrofuran (THF) or CH2Cl2 gives several complexes depending on the experimental conditions. Elemental analyses, IR, Raman, 13C[1H], 1H NMR and mass spectroscopies indicated the formation of mononuclear and dinuclear complexes. In the absence of NEt3 as proton quencher, the protonated ligands react in their zwitterionic form giving dinuclear [M(LH)X2]2 [M = Zn (1), Cd (2); LH = a, b; X = Cl, Br, I] or mononuclear M(NO3)2(LH)2 [M = Zn (5), Cd (6); LH = a] complexes. In both cases, coordination occurs through the S atoms, the ligands acting as terminal and bridging species. With NEt3, the deprotonated ligands are chelated through their N and S atoms and bridging occurs through the S atoms in [MLX]2 [M = Zn (3), Cd (4); LH = a; X = Cl, Br] complexes. The LH ligand is chemically grafted onto silica, the procedure optimized and the resulting material characterized by 13C and 29Si cross-polarization, magic-angle spinning (CP-MAS) NMR and DRIFT. This material is evaluated as a supported molecular trap for binding heavy metals (Cd2+, Hg2+, Pb2+) in aqueous solution. In both batch and column processes, it appears that Hg2+ and Pb2+ are trapped more than Cd2+, but in all cases values lower than those allowed were obtained.

The role of computed tomography in the management of acute pancreatitis.

Sixty-three patients with the clinical diagnosis of acute pancreatitis were submitted to contrast enhanced CT examination. As compared to Ranson's objective clinical parameters, CT grading according to Hill et al. as modified by Balthazar et al. was found to reflect accurately the severity of acute pancreatitis. Evaluation of serial CT examination did not reveal any significant progression in classification during the course of acute pancreatitis. The presence of hypodense areas in the pancreas as a single parameter seems to have a distinct prognostic value. In only one out of five pancreatic abscesses was the presence of gas bubbles observed on CT. It is concluded that contrast enhanced CT has a definite place in the management of acute pancreatitis.