Nanoscale relationships between uranium and carbonaceous material in alteration halos around unconformity-related uranium deposits of the Kiggavik camp, Paleoproterozoic Thelon Basin, Nunavut, Canada

International audienceConcentrations of 7% U and 1% Cu were identified in massive, brecciated, and amorphous carbonaceous materials (CM) characterized by strongly negative values of carbon stable isotopes (δ13C = − 39.1‰ relative to PDB). The anomalies are restricted to clay alteration halos developed in Neoarchean Woodburn Lake group metagreywacke that is the predominant host of unconformity-related uranium (U) deposits in the Kiggavik exploration camp. Petrographic and microstructural analyses by SEM, X-Ray Diffraction, HR-TEM and RAMAN spectroscopy identified carbon veils, best described as graphene-like carbon, upon which nano-scale uraninite crystals are distributed. CM are common in U systems such as the classic Cretaceous roll-front deposits and the world-class Paleoproterozoic unconformity-related deposits. However, the unusual spatial and textural association of U minerals and CM described herein raises questions on mechanisms that may have been responsible for the precipitation of the CM followed by crystallization of U oxides on its surfaces. Based on the characteristics presented herein, the CMs at Kiggavik are interpreted as hydrothermal in origin. Furthermore, the nanoscale organization and properties of these graphene-like layers that host U oxide crystallites clearly localized U oxide nucleation and growth

Micropollutants removal in tertiary moving bed biofilm reactors (MBBRs): Contribution of the biofilm and suspended biomass

The performance of tertiary moving bed biofilm reactors (MBBRs) was evaluated in terms of micropollutants (MPs) removal from secondary-treated municipal wastewater. After stepwise establishment of a mature biofilm, monitored by scanning electron and confocal microscopies, abiotic and biotic removals of MPs were deeply studied. Since no MPs reduction was observed by the both photodegradation and volatilization, abiotic removal of MPs was ascribed to the sorption onto the biomass. Target MPs i.e. Naproxen, Diclofenac, 17ß-Estradiol and 4n-Nonylphenol, arranged in the ascending order of hydrophobicity, abiotically declined up to 2.8%, 4%, 9.5% and 15%, respectively. MPs sorption onto the suspended biomass was found around two times more than the biofilm, in line with MPs’ higher sorption kinetic constants (ksor) found for the suspended biomass. When comparing abiotic and biotic aspects, we found that biotic removal outperformed its counterpart for all compounds as Diclofenac, Naproxen, 17ß-Estradiol and 4n-Nonylphenol were biodegraded by 72.8, 80.6, 84.7 and 84.4%, respectively. The effect of the changes in organic loading rates (OLRs) was investigated on the pseudo-first order degradation constants (kbiol), revealing the dominant biodegradation mechanism of co-metabolism for the removal of Diclofenac, Naproxen, and 4n-Nonylphenol., while 17ß-Estradiol obeyed the biodegradation mechanism of competitive inhibition. Biotic removals and kbiol values of all MPs were also seen higher in the biofilm as compared to the suspended biomass. To draw a conclusion, a quite high removal of recalcitrant MPs is achievable in tertiary MBBRs, making them a promising technology that supports both pathways of co-metabolism and competitive inhibition, next to the abiotic attenuation of MPs

Impact of fermentation conditions on the production of bioactive compounds with anticancer, anti-inflammatory and antioxidant properties in kombucha tea extracts

The production of natural bioactive compounds through the fermentation of plants has increased in recent years. The biological activities of the extracts obtained from the fermentation of black tea with the kombucha consortium were evaluated. To improve the productivity of these compounds two different vessel geometries were used and successive extractions with solvents of increasing polarity were performed. Forty-seven compounds were identified by GC–MS, including several organic acids and phenolic compounds. Total phenolic content, pH value, and antioxidant, antiproliferation and anti-inflammatory activities were measured after 21 days of fermentation. A higher surface/height (s/h) ratio seemed to enhance the anti-inflammatory activity of kombucha tea, resulting in IC50 value of 9.0 ± 0.1 μg/mL compared to 24.3 ± 0.2 μg/mL with the lowest ratio. Regarding the anticancer activity, the highest inhibition percentage of 55.3% at 50 μg/mL against the HCT-116 human colon carcinoma cell line was obtained with the ethyl acetate extract after 21 days of fermentation compared to the value of 8% obtained with the same extraction solvent using the non-fermented black tea. These results showed that fermentation may improve the biological activities of the tea and that the production of bioactive compounds can vary depending on the fermentation condition

40 exercices ludiques pour la formation : savoir impliquer les apprenants /

2e éd.Bibliogr

Surprendre en formation : 45 outils ludopédagogiques - Donner envie d'apprendre

4e édition 2017Comprend un inde

Radioactivity recorded by clay minerals in the Shea Creek area, Athabasca Basin (Canada): Implications for uranium transfers and exploration

International audienceThe understanding of uranium mobility in the geosphere is a prerequisite for the modelling of high-level nuclear waste repositories and economic uranium deposit genesis. To complement more classical geochemical and mineralogical approaches, this understanding can be improved by measuring the record of past cumulative radioactivity as stable radiation-induced defects in clay mineral structure. This study focuses on world-class unconformity-related uranium deposits of the Athabasca Basin (Canada) for which the source, timing, and paths of the uranium-bearing fluids are still matters of debate. A set of 46 samples collected from the Athabasca Group sandstones in the Shea Creek area of the western Athabasca Basin, up to 634 m above either the unconformity (barren drill hole) or uranium mineralization, was selected in order to locate the paleo-occurrences of radio-elements. A relevant three-dimensional view is shown by plotting (i) the concentrations of radiation-induced defects (RID's) in clay minerals, (ii) the present dose rate, and (iii) the distance to the mineralization or un-conformity. The results clearly reveal different cases, such as geochemical background, equilibrated dose rate, late accumulations of radioelements, and/or records of their past temporary occurrence. Noticeable paleo-occurrences , now leached away, are revealed within 100 m of the structures hosting present-day mineralized bodies, which is in line with a recent model of long range lateral paleofluid flow in a basinal permeable formation , and may be useful for exploration, albeit within a proximal range. Such results rely on the detection of RID's in clay minerals, as chemical analysis or gamma counting alone detect only the present concentration of radioelements and are unable to distinguish between accumulations, equilibration of transfers, or temporary occurrences of uranium. This study represents a first step toward spatial 3D quantitative reconstruction of U transfers, which will require time constraints and artificial dosimetry to improve models of genesis of high-grade unconformity-related deposits and to identify paleo-pathways of U migration

The thermal stability of radiation-induced defects in illite

International audienc

Ti2AlN thin films synthesized by annealing of (Ti plus Al)/AlN multilayers

Single-phase Ti2AlN thin films were obtained by annealing in vacuum of (Ti + Al)/AIN multilayers deposited at room temperature by magnetron sputtering onto single-crystalline (0001) 4H-SiC and (0001) Al2O3 substrates. In-situ X-ray diffraction experiments combined with ex-situ cross-sectional transmission electron microscopy observations reveal that interdiffusion processes occur in the multilayer at a temperature of similar to 400 degrees C leading to the formation of a (Ti, Al, N) solid solution, having the hexagonal structure of alpha-Ti, whereas the formation of Ti2AlN occurs at 550-600 degrees C. Highly oriented (0002) Ti2AlN thin films can be obtained after an annealing at 750 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.Funding Agencies|University of Poitiers; European Research Council under the European Communitys Seventh Framework Programme/ERC [335383]; Swedish Foundation for Strategic Research through the Future Leaders 5 program</p

eLite-HTS : un outil TAL pour la génération de synthèse HMM en français

Nous proposons une démonstration du service web eLite-HTS disponible à l’adresse http ://cental.uclouvain.be/elitehts/v1 qui génère, à partir d’un texte, un fichier de description linguistique contenant les informations nécessaires pour l’entraînement et la génération d’un système desynthèse vocale HMM en français, basé sur l’outil HTS. Les informations linguistiques sont générées automatiquement grâce à une adaptation du module TAL intégré dans le synthétiseur vocal eLite