The power of iron catalysis in diazo chemistry

The use of iron catalysis to enable reactions with diazo compounds has emerged as a valuable tool to forge carbon–carbon or carbon–heteroatom bonds. While diazo compounds are often encountered with toxic and expensive metal catalysts, such as Rh, Ru, Pd, Ir, and Cu, a resurgence of Fe catalysis has been observed. This short review will showcase and highlight the recent advancements in iron-mediated reactions of diazo compounds

Dosage des composés chlorofluorocarbonés et du tétrachlorure de carbone dans les eaux souterraines. Application à la datation des eaux.

Cahiers Techniques de Géosciences Rennes n°4Les chlorofluorocarbones (CFC) et le CCl4 sont dosés dans les eaux souterraines à laide de latechnique dite du Purge and Trap et dun chromatographe en phase gazeuse équipé dundétecteur ECD. Ils permettent destimer lâge de leau, cest à dire le temps depuis lequelleau a quitté le contact de latmosphère, ou la zone non saturée du sol. La méthode permetde dater des eaux de 1950 à nos jours. Les concentrations mesurées sont de lordre de lapicomole par litre deau et du pptv dans lair (partie par trillion de volume). Les techniques deprélèvement, déchantillonnage et de conservation ont été validées afin de ne pas contaminerles échantillons. La méthode développée permet datteindre des limites de détection de lordrede 0,01 picomole par litre deau (0,01*10-12 mole/L) pour le CFC-12. Les incertitudes sur lesâges déterminés peuvent être inférieures à quatre ans dans les cas favorables

Global and full-depth ocean temperature trends during the early twenty-first century from Argo and repeat hydrography

The early 21st century’s warming trend of the full-depth global ocean is calculated by combining the analysis of Argo (top 2000m) and repeat hydrography into a blended full-depth observing system. The surface-to-bottom temperature change over the last decade of sustained observation is equivalent to a heat uptake of 0.72 ± 0.09 W m?2 applied over the surface of the earth, 90% of it being found above 2000m depth. We decompose the temperature trend point-wise into changes in isopycnal depth (heave) and temperature changes along an isopycnal (spiciness) to describe the mechanisms controlling the variability. The heave component dominates the global heat content increase, with the largest trends found in the southern hemisphere’s extratropics (0 - 2000m) highlighting a volumetric increase of subtropical mode waters. Significant heave-related warming is also found in the deep North Atlantic and Southern Ocean (2000m - 4000m), reflecting a potential decrease in deep water mass renewal rates. The spiciness component shows its strongest contribution at intermediate levels (700m - 2000m), with striking localised warming signals in regions of intense vertical mixing (North Atlantic and Southern oceans). Finally, the agreement between the independent Argo and repeat hydrography temperature changes at 2000m provides an overall good confidence in the blended heat content evaluation on global and ocean scales, but also highlights basin scale discrepancies between the two independent estimates. Those mismatches are largest in those basins with the largest heave signature (Southern Ocean) and reflect both the temporal and spatial sparseness of the hydrography sampling

Reconciling strontium-isotope and K-Ar ages with biostratigraphy: the case of the Urgonian platform, Early Cretaceous of the Jura Mountains, Western Switzerland

During the late Early Cretaceous, the shallow-water domains of the western Tethys are characterized by the widespread deposition of Urgonian-type carbonates rich in rudists, corals and other oligotrophic, shallow-marine organisms. In the Helvetic Alps, the Urgonian occurrences have been dated by ammonite biostratigraphy as Late Barremian and Early Aptian. For the more proximal occurrences in the western Swiss Jura, a recent age model based on bio-, chemo- and sequence stratigraphy has been proposed, which allows for an improved correlation with the Helvetic counterparts. In order to corroborate the recently proposed age model for the Jura, a set of well-preserved rhynchonellids collected from five different lithostratigraphical formations and members ("Marnes bleues d'Hauterive”, "Marnes d'Uttins”, basal marly layers within the "Urgonien Jaune”, "Marnes de la Russille”, "Urgonien Blanc”) has been analysed for its strontium-isotope ratios (87Sr/86Sr). In addition, K-Ar dating was performed on well-preserved glauconite grains from two different levels ("Marnes d'Uttins” and a basal layer within the "Urgonien Jaune”). The correlation of the Sr-isotope data set with a belemnite-based, ammonite-calibrated reference curve provides an age model which is coherent with recently published ages based on calcareous nannofossil biostratigraphy and the correlation of trends in chemo- and sequence stratigraphy. K-Ar dating on well-preserved glauconite grains from the "Marnes d'Uttins” and lowermost part of the "Urgonien Jaune” delivered ages of 127.5±2.3 and 130.7±2.6Ma, respectively. Whereas the age of the glauconitic level near the base of the "Urgonien Jaune” is chronostratigraphically meaningful, the K-Ar age of the "Marnes d'Uttins” appears too young relative to the presently used time scale. This may be related to rejuvenation of the K-Ar chronometer due to post-depositional Ar loss, most likely during hardground formation. The ages obtained here confirm the Late Barremian age for the onset of the Urgonian platform, an age which is conform with ages obtained in the Helvetic Alps and elsewhere along the northern Tethyan margi

Inter-comparison exercises on dissolved gases for groundwater dating - (1) Goals of the exercise and site choice, validation of the sampling strategy

International audienceTwo international inter-comparison exercises devoted to dissolved gases and isotope analyses in groundwater, used as tools for groundwater dating were organized in 2012 in France (IDES- Université Paris Sud - CNRS and OSUR - Université Rennes 1- CNRS). The goal was to compare sampling and analytical protocols through results obtained by the community of groundwater dating laboratories. The two exercises were: GDAT1 on three supply boreholes in a homogeneous sand-aquifer of Fontainebleau (Paris Basin, France) and GDAT2 on two supply boreholes (shallow and deep) in a fractured rock aquifer in French Brittany. This twostep exercise is the first exercise which included a large number of gases and isotopes usually used in groundwater as dating tools and also permit to discuss the uncertainties related to sampling protocols issuing from each laboratory methods. The two tests allowed 31 Laboratories from 14 countries to compare their protocols for both sampling and analyses. This paper presents the participants and parameters measured, and focuses on the validation of the sampling strategy. Two laboratories analyzed CFC and SF6 samples collected at regular intervals during the sampling operations in order to verify water homogeneity. The results obtained by the two "reference" laboratories along with monitoring of field parameters showed no clear trend of gas concentration or physic-chemical properties. It can be concluded that the pumped groundwater composition remained constant during sampling. This study also shows the potential for relatively constant pumped groundwater composition from a specific well despite the complexity and/or mixing processes that may occur at a larger scale in the aquifer

High cadmium concentrations in Jurassic limestone as the cause for elevated cadmium levels in deriving soils: a case study in Lower Burgundy, France

Cadmium (Cd) is a highly toxic element and its presence in the environment needs to be closely monitored. Recent systematic surveys in French soils have revealed the existence of areas in eastern and central France, which show systematically high cadmium concentrations. It has been suggested that at least part of these anomalous levels are of natural origin. For the Lower Burgundy area in particular, a direct heritage from the Jurassic limestone bedrock is highly suspected. This potential relationship has been studied in several localities around Avallon and this study reports new evidence for a direct link between anomalously elevated cadmium contents of Bajocian and Oxfordian limestone and high cadmium concentrations in deriving soils. Soils in this area show cadmium concentrations generally above the average national population values, with contents frequently higher than the ‘upper whisker' value of 0.8μgg−1 determined by statistical evaluation. In parallel, limestone rocks studied in the same area exhibit cadmium concentrations frequently exceeding the mean value of 0.030-0.065μgg−1 previously given for similar rocks by one order of magnitude, with a maximum of 2.6μgg−1. Mean ratios between the cadmium concentrations of limestone bedrock and deriving soils (Cdsoil/Cdrock), calculated for different areas, range from 4.6 to 5.7. Calculations based on the analyses of both soils from a restricted area and fragments of bedrock sampled in the immediate vicinity of high-concentration soils are around 5.5-5.7. Cdsoil/Cdrock is useful in determining the potential of soils in Lower Burgundy to reflect and exacerbate the high concentrations of cadmium present in parent bedrock

Proteomic profile determination of autosomal aneuploidies by mass spectrometry on amniotic fluids

<p>Abstract</p> <p>Background</p> <p>Prenatal diagnosis of chromosomal abnormalities by cytogenetic analysis is time-consuming, expensive, and requires highly qualified technicians. Rapid diagnosis of aneuploidies followed by reassurance of women with normal results can be performed by molecular analysis of uncultured foetal cells. In the present study, we developed a proteomic fingerprinting approach coupled with a statistical classification method to improve diagnosis of aneuploidies, including trisomies 13, 18, and 21, in amniotic fluid samples.</p> <p>Results</p> <p>The proteomic spectra obtained from 52 pregnant women were compiled, normalized, and mass peaks with mass-to-charge ratios between 2.5 and 50 kDa identified. Peak information was combined together and analysed using univariate statistics. Among the 208 expressed protein peaks, 40 differed significantly between aneuploid and non aneuploid samples, with AUC diagnostic values ranging from 0.71 to 0.91. Hierarchical clustering, principal component analysis and support vector machine (SVM) analysis were performed. Two class predictor models were defined from the training set, which resulted in a prediction accuracy of 92.3% and 96.43%, respectively. Using an external and independent validation set, diagnostic accuracies were maintained at 87.5% and 91.67%, respectively.</p> <p>Conclusion</p> <p>This pilot study demonstrates the potential interest of protein expression signature in the identification of new potential biological markers that might be helpful for the rapid clinical management of high-risk pregnancies.</p

Sustainability of the new Argo mission

Report on the progress made on the sustainability of the new Argo missio

The Galactic Isotropic γ\gamma-ray Background and Implications for Dark Matter

We present an analysis of the radial angular profile of the galacto-isotropic (GI) $\gamma$-ray flux--the statistically uniform flux in circular annuli about the Galactic center. Two different approaches are used to measure the GI flux profile in 85 months of Fermi-LAT data: the BDS statistic method which identifies spatial correlations, and a new Poisson ordered-pixel method which identifies non-Poisson contributions. Both methods produce similar GI flux profiles. The GI flux profile is well-described by an existing model of bremsstrahlung, $\pi^0$ production, inverse Compton scattering, and the isotropic background. Discrepancies with data in our full-sky model are not present in the GI component, and are therefore due to mis-modeling of the non-GI emission. Dark matter annihilation constraints based solely on the observed GI profile are close to the thermal WIMP cross section below 100 GeV, for fixed models of the dark matter density profile and astrophysical $\gamma$-ray foregrounds. Refined measurements of the GI profile are expected to improve these constraints by a factor of a few.Comment: 20 pages, 15 figures, references adde