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Fonte: wiley Publicador: wiley
Tipo: Artigo de Revista Científica
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An integrated, multi-analytical approach combining the high sensitivity of SR-mXRF, the light element capability of PIXE/PIGE under a helium flux and the spatial resolution of BSEM + EDS was used to characterize chemical composition and corrosion of glass samples(first to fourth centuries AD) from an important, but scarcely investigated, Roman region of south-west Iberia (southern Portugal). The geochemical trends and associations of major, minor and trace elements were investigated to shed light on production techniques, the provenance of raw materials and decay mechanisms. The results, while confirming a production technique common to Roman glasses throughout the Empire—that is, a silica-soda-lime low-Mg, low-K composition, with glass additives as colouring and/or decolouring agents (Fe,Cu, Mn, Sb)—show at one site high Zr–Ti contents, suggesting a more precise dating for these glasses to the second half of the fourth century. The Ti–Fe–Zr–Nb geochemical correlations in the pristine glass indicate the presence of minerals such as ilmenite, zircon, Ti-rich Fe oxides and columbite in the sands used as raw materials for the glass former: these minerals are typical of granitic-type source rocks. The unusually high K content in the corrosion layers is consistent with burial conditions in K-rich soils derived from the alteration of 2:1 clays in K-bearing rock sequences.

Spatial distribution of the trace elements zinc, strontium and lead in human bone tissue☆

Pemmer, B.; Roschger, A.; Wastl, A.; Hofstaetter, J.G.; Wobrauschek, P.; Simon, R.; Thaler, H.W.; Roschger, P.; Klaushofer, K.; Streli, C.
Fonte: Elsevier Science Publicador: Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em /11/2013 EN
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Trace elements are chemical elements in minute quantities, which are known to accumulate in the bone. Cortical and trabecular bones consist of bone structural units (BSUs) such as osteons and bone packets of different mineral content and are separated by cement lines. Previous studies investigating trace elements in bone lacked resolution and therefore very little is known about the local concentration of zinc (Zn), strontium (Sr) and lead (Pb) in BSUs of human bone. We used synchrotron radiation induced micro X-ray fluorescence analysis (SR μ-XRF) in combination with quantitative backscattered electron imaging (qBEI) to determine the distribution and accumulation of Zn, Sr, and Pb in human bone tissue.

Arsenic speciation in fluid inclusions using micro-beam X-ray absorption spectroscopy

James-Smith, J.; Cuazid, J.; Testemale, D.; Liu, W.; Hazemann, J.L.; Proux, O.; Etschmann, B.; Philippot, P.; Banks, D.; Williams, P.; Brugger, J.
Fonte: Mineralogical Soc Amer Publicador: Mineralogical Soc Amer
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
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Synchrotron radiation X-ray fluorescence (SR-XRF) was used to characterize As speciation within natural fluid inclusions from three deposits with different hydrogeochemical and geological settings. The studied samples represent different compositions of Au-bearing fluids: typical orogenic Au deposit (low-salinity, ~6 mol% CO2 ± CH4; Brusson, Western Italian Alps); brines from a Proterozoic (Fe)- Cu-Au deposit (Starra, Queensland, Australia); and an As-rich magmatic fluid with a bulk composition similar to that typical of orogenic gold (Muiane pegmatite, Mozambique). Arsenic K-edge X-ray absorption spectra (XAS) were obtained from fluid inclusions at temperatures ranging from 25 to 200°C, and compared with spectra of aqueous As(III) and As(V) solutions and minerals. X-ray absorption near edge structure (XANES) data show that initially the fluid inclusions from all three regions contain some As in reduced form [As(III) at Brusson and Muiane; As-sulfide or possibly As(0) at Starra]. However, this reduced As is readily oxidized under the beam to As(V). Therefore, extended X-ray absorption fine structure (EXAFS) spectra for the As(III) aqueous complex could be collected only on the sample from the Muiane pegmatite containing large fluid inclusions with high As concentrations (>>1000 ppm). Analysis of these EXAFS data shows that As(OH)3(aq) (coordination number of 3.0 ± 0.2 atoms...

Element distribution imaging in rat kidney using a 2D rapid scan EDXRF device

Figueroa,R.G.; Lozano,E.; Bongiovanni,G.
Fonte: Sociedad Mexicana de Física Publicador: Sociedad Mexicana de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2013 EN
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Visualization of elemental distributions of biological tissue is gaining importance in many disciplines of biological, forensic, and medical research. Furthermore, the maps of elements have wide application in archeology for the understanding of the pigments, modes of preservation and environmental context. Since major advances in relation to collimators and detectors have yielded micro scale images, the chemical mapping via synchrotron scanning micro-X-ray fluorescence spectrometry (SR-µXRF) is widely used as microanalytical techniques. However, the acquisition time is a limitation of current SR-µXRF imaging protocols, doing tedious micro analysis of samples of more than 1 cm and very difficult to study of larger samples such as animal organ, whole organisms, work of art, etc. Recently we have developed a robotic system to image the chemistry of large specimens rapidly at concentration levels of parts per million. Multiple images of distribution of elements can be obtained on surfaces of 100x100 mm and a spatial resolution of up to 0.2 mm² per pixel, with a spectral capture time up to 1 ms per point. This system has proven to be highly efficient for the XRF mapping of elements in large biological samples, achieving comparables results to those obtained by SR-µXRF. Thus...