STED nanoscopy : A novel way to image the pore space of geological materials

STED nanoscopy (Stimulated Emission Depletion). which can resolve details far below the diffraction barrier has been applied hitherto preferentially to life sciences. The method is however also ideal for the investigation of geological matrices containing transparent minerals, an application tested here, to our knowledge, for the first time. The measurements on altered granitic rock and sedimentary clay rock, both containing very fine-grained phases, were conducted successfully. The STED fluorophore was dissolved in C-14-labelled methylmethacrylate (C-14-MMA) monomer which was polymerised within the rock matrix, thereby labelling the pore space in the geomaterials. Double labelling provided by the C-14-labelled MMA enables autoradiography and scanning electron microscopy (SEM), providing necessary complementary information for characterisation and quantification of porosity distributions and mineral and structure identification. Promising perspectives for further investigations of geological matrices by using different fluorophores and the optimisation of measuring procedures or even higher resolution are discussed. The combination of these different methods enlarges the observation scale of porosity from nanometre to centimetre scale.Peer reviewe

Mapping U-238 decay chain equilibrium state in thin sections of geo-materials by digital autoradiography and microprobe analysis

A new approach is proposed in order to spatially localize and determine the equilibrium state of natural decay chains on hand-scale geological samples, thanks to a combination of three techniques: 1) Elementary chemical mapping by microprobe; 2) Alpha autoradiograph by gaseous detectors and 3) bulk alpha particle spectrometry. The quantitative nature of alpha autoradiograph and its comparison with U chemical maps allows to locate radioactive equilibrium state in four samples. This equilibrium state was confirmed by alpha spectrometry analysis.Peer reviewe

FLIM FRET Technology for Drug Discovery: Automated Multiwell-Plate High-Content Analysis, Multiplexed Readouts and Application in Situ**

A fluorescence lifetime imaging (FLIM) technology platform intended to read out changes in Förster resonance energy transfer (FRET) efficiency is presented for the study of protein interactions across the drug-discovery pipeline. FLIM provides a robust, inherently ratiometric imaging modality for drug discovery that could allow the same sensor constructs to be translated from automated cell-based assays through small transparent organisms such as zebrafish to mammals. To this end, an automated FLIM multiwell-plate reader is described for high content analysis of fixed and live cells, tomographic FLIM in zebrafish and FLIM FRET of live cells via confocal endomicroscopy. For cell-based assays, an exemplar application reading out protein aggregation using FLIM FRET is presented, and the potential for multiple simultaneous FLIM (FRET) readouts in microscopy is illustrated

Minéralogie, porosité et diffusion des solutés dans l'argilite du Callovo-Oxfordien de Bure (Meuse, Haute-Marne, France) de l'échelle centimétrique à micrométrique

A l échelle mésoscopique (~cm- m), la diffusion des solutés ioniques dans l argilite du Callovo-Oxfordien de Bure (Meuse/Haute Marne, France) dépend de l organisation spatiale de la porosité et des minéraux (principalement argiles, carbonates et quartz). L'obtention de cartes minérales 2-D (microscopie électronique) ou 3-D (microtomographie de rayons X) est rendu possible par le développement de techniques de segmentation spécifiques. Les cartes de porosité obtenues par la méthode 3H-PMMA sont clairement corrélées à la minéralogie. Elles démontrent que les porosités locales (~ m) et globales (~cm) dépendent principalement de la teneur en minéraux argileux, les quartz et les carbonates pouvant être considérés comme non poreux. La diffusion des solutés a été modélisée à partir de la distribution spatiale 3-D réelle des minéraux et de la porosité. Cette approche a permis de quantifier le rôle des minéraux non poreux sur la géométrie des chemins de diffusion dans l argilite. Le facteur de géométrie des chemins de diffusion a été corrélé à la teneur et la morphologie des minéraux non poreux. Les résultats obtenus ont mis en évidence une anisotropie de diffusion due à l orientation préférentielle des grains de quartz et de carbonates dans le plan de sédimentation. A partir de méthodes de cartographies élémentaires, la distribution spatiale de l ion Cu2+ et des minéraux a été acquise à l échelle mésoscopique après une expérience de diffusion. Les résultats expérimentaux confirment les liens existant entre diffusion et minéralogie.In Bure Callovo-Oxfordian argillite (Meuse/Haute Marne, France), the spatial organisation of porosity and minerals (mainly quartz, carbonates, and clays) controls the solute diffusion at mescoscopic scale (~cm- m). New developments in the field of image analysis were devoted to extract mineral maps from 2-D (scanning electron microscopy) and 3-D (X-ray microtomography) imaging techniques. The porosity maps provided by the 3H-PMMA method demonstrate that porosity and mineral distributions are clearly correlated. The local (~ m) and global (~cm) porosity depend mainly on clay mineral content, carbonates and quartz being unporous. Solute diffusion was modelled from actual 3-D mineral and porosity spatial distribution. Using this numerical approach, diffusion pathways were quantified according to the mineral distribution. The geometry factor was correlated to the fraction and the morphology of unporous mineral. A diffusion anisotropy due to the preferential orientation of carbonates and quartz was also underlined by this approach. In an experimental way, Cu2+ diffusion and mineral was visualised and quantify at mescoscopic scale from elemental mapping methods. These techniques provide various relationships between Copper distribution and mineralogy.POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Pétrographie et pétrophysique des matrices granitique (relation entre porosité et propriétés de transport)

Le stockage de déchets nucléaires en milieux géologiques profonds est une méthode permettant d'isoler ces déchets de l'environnement. L'objet de cette étude est la détermination de deux paramètres importants (porosité, diffusion) permettant de retarder le passage des radionucléides dans la biosphère. Différentes expériences (MEB, autoradiographie) ainsi que des méthodes d'analyses d'images ont été mises en place afin d'étudier la porosité en fonction de la minéralogie des granitoïdes non altérés et altérés de Charroux-Civray par une approche multi-échelle. Puis, des expériences de perméabilité et de diffusion ont été réalisées sur les roches non altérés de manière à mesurer des paramètres ne prenant pas en compte l'hétérogénéité de la roche. Finalement, l'expérience d'out-diffusion a été modélisée par la méthode TDD. En utilisant l'autoradiographie, il est possible de calculer par inversion des coefficients de diffusion locaux en ajustant la simulation numérique à la courbe expérimentale.Disposal in deep, stable bedrock is currently one concept for isolating high-level nuclear wastes from the environment. This work deals with the determination of two important parameters (porosity and diffusion) that control over the ability of granitoid matrices to retain the radionucleides if they escape from the repository into the bedrock. Different experimental methods (SEM, Autoradiography) and image analysis methods are performed to study porosity of unaltered and altered Charroux-Civray granitoid in relationship with the mineralogy from the decimeter scale to the infra-micrometer scale. Then, different transport experiments are performed (permeability, in- and out-diffusion) with unaltered sample in order the measure bulk parameters. Moreover, the out-diffusion experiment is modelled using a particle tracking method. Using autoradiograph and the mineral map, an inversion procedure is performed in order to adjust the numerical simulation to the experimental out-diffusion curve.POITIERS-BU Sciences (861942102) / SudocSudocFranceF