Fluid inclusion depth and thickness estimates using a Na nuclear reaction resonance and Si elastic scattering

International audienceAn important aspect of quantitative fluid inclusion analysis using X-ray emission techniques concerns a knowledge of fluid inclusion depth and geometry to establish reliable absorption correction procedures. The aim of this study is to assess the potential performance of the nuclear reaction 23Na(p, p′γ)23Na in estimating inclusion depth. Na was chosen because of its common occurrence in natural fluids. The nuclear reaction displays a characteristic, low energy resonance peak at 1.283 MeV in its cross-section which, together with recognition that the energy of the incident particles traversing matter decreases predictably with depth, allow estimation of the thickness of quartz traversed by the beam and hence the inclusion depth. Results of the calculation shows accuracy on estimated fluid inclusion depths commonly better than ±0.5 μm. In addition, following the same experimental protocol as defined for Na, we show how the use of the elastic scattering reaction 28Si(p, p)28Si can provide information on the fluid inclusion thickness

Iron distribution in cancer cells following doxorubicin exposure using proton and X-ray synchrotron radiation microprobes

International audienceChemical studies have shown that doxorubicin, a well-established anticancer agent, is a powerful iron chelator and the resultant iron - drug complex is an efficient catalyst of the conversion of hydrogen peroxide to the highly reactive hydroxyl radical. However, the intracellular complexation of doxorubicin with iron is still debated. Using nuclear microprobe analysis (NMPA), we previously observed in human ovarian cancer cells exposed to 20 μM iodo-doxorubicin (IDX) that iodine and iron cellular distributions were spatially correlated, suggesting a mechanism of intracellular iron chelation by the anthracycline compound. Because maximal plasma drug concentrations in patients are expected to be around 5 μM, NMPA and X-ray absorption near edge spectroscopy (XANES) experiments for iron speciation analysis were performed on cultured cells exposed to pharmacological doses of 2 μM IDX or doxorubicin

X-ray microspectroscopy of sulfur in basaltic glass inclusions. Inference on the volcanic sulfur emissions.

It is commonly accepted that sulfur is carried out as sulfide (S $\rm ^{II-}$) or/and sulfate (S $\rm ^{VI}$) by Earth mantlederived melts, before being released as SO 2 and/or H 2S in volcanic emissions. By analyzing reference compounds and a selection of minute glass inclusions in olivine crystals using $\mu$XANES (X-ray Near Edge Structure) spectroscopy at the sulfur K-edge, we demonstrated the ubiquitous presence of sulfite (S $\rm ^{IV}$) in addition to sulfate (S $\rm ^{VI}$) in these rare inclusions representative of oxidized and water rich-basaltic magmas, prior to loss of sulfur and water. The sulfide (S $\rm ^{II-}$) when exists is minor. We proposed that sulfite (S $\rm ^{IV}$) acts as an intermediate, metastable species which results in partitioning of sulfur into the volcanic gas emissions

Chromium mapping in male mice reproductive glands exposed to CrCl3 using proton and X-ray synchrotron radiation microbeams

Preconception exposure to certain chemicals may increase risk of tumors in offspring, especially with regard to occupational metals such as chromium. However, the mechanism of chromium trans-generation carcinogenicity remains unknown. Using scanning proton X-ray microanalysis we have been able to detect chromium in testicular tissue sections from mice treated by intraperitoneal injection of 1 mmol/kg CrCl3. Chromium concentration was about 5 μg/g dry mass in average, but higher concentrations were found within the limiting membrane of the testes, the tunica albuginea. In addition, synchrotron radiation X-ray fluorescence measurements, with microscopic resolution, clearly demonstrated the presence of chromium in the tunica albuginea but also within isolated cells from the interstitial connective tissue

Biological fluxes conversion and SXRF experiment with a new active biomonitoring tool for atmospheric metals and trace element deposition

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Silicate Glasses

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