The sequence to hydrogenate coronene cations:A journey guided by magic numbers

The understanding of hydrogen attachment to carbonaceous surfaces is essential to a wide variety of research fields and technologies such as hydrogen storage for transportation, precise localization of hydrogen in electronic devices and the formation of cosmic H2. For coronene cations as prototypical Polycyclic Aromatic Hydrocarbon (PAH) molecules, the existence of magic numbers upon hydrogenation was uncovered experimentally. Quantum chemistry calculations show that hydrogenation follows a site-specific sequence leading to the appearance of cations having 5, 11, or 17 hydrogen atoms attached, exactly the magic numbers found in the experiments. For these closed-shell cations, further hydrogenation requires appreciable structural changes associated with a high transition barrier. Controlling specific hydrogenation pathways would provide the possibility to tune the location of hydrogen attachment and the stability of the system. The sequence to hydrogenate PAHs, leading to PAHs with magic numbers of H atoms attached, provides clues to understand that carbon in space is mostly aromatic and partially aliphatic in PAHs. PAH hydrogenation is fundamental to assess the contribution of PAHs to the formation of cosmic H2.</p

Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix

The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix

Promotion of avian endothelial cell differentiation by GATA transcription factors

AbstractIn the avian embryo, endothelial cells originate from several sources, including the lateral plate and somite mesoderm. In this study, we show that Gata transcription factors are expressed in the lateral plate and in vasculogenic regions of the avian somite and are able to promote a vascular endothelial fate when ectopically expressed in somite precursors. A fusion of GATA4 to the transcriptional activator VP16 promoted endothelium formation, indicating that GATA transcription factors promote vasculogenesis via activation of downstream targets, while a fusion of GATA4 to the transcriptional repressor engrailed repressed expression of Vascular Endothelial Growth Factor Receptor 2, a marker of endothelial precursors. These findings indicate a role for GATA transcription factors in the differentiation of the endothelium

Lymphoepithelioma-like carcinoma of the vulva, an underrecognized entity? Case report with a single inguinal micrometastasis detected by sentinel node technique

This report describes an unusual EBV-negative lymphoepithelioma-like carcinoma of the vulva in a 73-year-old patient. The lesion was localised at the right minor labium and was resected by partial vulvectomy. A synchronous sentinel lymph node biopsy revealed a single micrometastasis in the right inguinal region, which prompted local radiotherapy. Follow-up nine months later showed only slight vulvar atrophy, without signs of local recurrence or distant metastases

Modèle de dépot, evolution diagénétique, propriétés physiques et analyse de sismique quantitative du réservoir carbonaté de gaz de Yadana (Offshore Birmanie)

The Yadana carbonate buildup is a mature gas field, located in the Andaman Sea, offshore Myanmar and producing since 1998. The reservoir is an isolated carbonate platform, Oligocene to Miocene in age, sealed below 1200 m of siliciclastic sediments. Predicting hydrocarbon resources and water flows during the production has become a major challenge for such mature carbonate gas fields. The present PhD work involves the implementation of a methodology that allows the construction of a detailed reservoir architecture that accounts for significant heterogeneity. The work is multiscale and multidisciplinary, covering discipline such as sedimentology, diagenesis, geochemistry, rock physics, geophysics and based on a large and comprehensive dataset including, cores, well logs, petrophysical measurements, production data and seismic data. First, three types of carbonate factory produced sediment on top of the platform under prevailing oligophotic to mesophotic conditions and periods of varying particulate organic matter supplies. The limited lateral changes in facies and the layer-cake depositional architecture inferred from well correlations, and the seismic expression suggest a deposition on a flat shelf. Carbonate production and accumulation were mainly controlled by light penetration, nutrient content and hydrodynamic conditions which are related to changes in monsoonal intensity, terrestrial runoff during the early Miocene in the Andaman Sea. Secondly, with an average porosity of 28%, the diagenesis is an important controlling factor of the reservoir properties. Mud-supported, coral-rich sediments record significant early marine dissolution of aragonite and early lithification of the matrix and a major decrease in porosity (up to10%) below the gas-water contact suggests a major phase of porosity evolution during and/or after the hydrocarbon emplacement. By modifying drastically porosity and pore networks, the diagenesis largely controls the acoustic architecture and seismic expression of the reservoir. The well-to-seismic tie allowed to precisely evidencing the origin of the main seismic reflectors. They may form, within the gas zone, at the boundary between two diagenetic/acoustic units or result from the interference between reflection at the base and top of such intervals. Early marine lithification of coral-rich intervals generates high amplitude and continuous reflectors and a stratigraphy-cross-cutting reflector forming at a major and laterally continuous shift in porosity relates differential diagenetic evolution between the gas and the water zones. Finally, because the scattering of the elastic properties at a given porosity in carbonate is mainly relative to pore type variations, a rock physics inversion scheme based on DEM approaches (Differential Effective Medium modeling; Xu and Payne 2009) has been developed to quantify the pore type effect from the well log and the seismic elastic properties. After the calibration of the method to the real pore type geometry from rock data, the inversion is performed (upscaling) on the 3D seismic data to map the geobodies relative to pore type variations. This approach allows a relevant prediction of geological seismic scale heterogeneity impacting for example the fluid flows and the water rises in the reservoir during the production.Providing a robust framework for the characterization of the Yadana gas reservoir, the thesis gives further insights into the understanding of geological and environmental factors controlling Cenozoic isolated carbonate systems in South East Asia. This work highlights the interdependence existing between geology and seismic imaging and demonstrates that an integrated geological/geophysical characterization of carbonate reservoirs are essential for both the exploration and the production of hydrocarbon resources.La plateforme carbonatée de Yadana est le réservoir principal d’un champ de gaz en Mer d’Andaman, au large des côtes Birmanes produisant depuis 1998. Le réservoir est d’âge Oligocène-Miocène et est scellé par 1200 m de sédiments silicoclastiques. Prédire les ressources en hydrocarbure et les mouvements des fluides durant la production est un challenge majeur pour ce champ devenu mature. Le présent travail de thèse met en place une méthodologie aboutissant à la construction détaillée de l’architecture du réservoir. Ce travail est multi-échelle, intégratif, multidisciplinaire couvrant des domaines tels que la sédimentologie, la diagenèse, la géochimie, la physique des roches, la géophysique et se base sur un large et complet jeu de données incluant des carottes, des diagraphies, des mesures petrophysiques, des données de production ainsi que des données de sismique 3D. D’un point de vue sédimentologique, trois types d’usines à carbonates ont été identifiés, produisant les sédiments au sommet de la plateforme dans des conditions oligophotiques à mésophotiques. Les faibles modifications latérales de facies et l’architecture de dépôt en couches stratifiées déduite des corrélations de puits et de l’imagerie sismique suggèrent un dépôt sur un haut-fond à faible relief. La production et l’accumulation des carbonates étaient, au début du Miocène principalement contrôlé par la pénétration de la lumière, la teneur en éléments nutritifs et les conditions hydrodynamiques elles-mêmes liées aux variations d’intensité de la mousson, aux apports terrigènes et à l’activité des courants d’upwelling en mer d’Andaman.Avec une porosité moyenne de 28%, la diagenèse est un facteur de contrôle important des propriétés réservoir. Les sédiments riches en coraux enregistrent une dissolution marine de l’aragonite ainsi qu’une lithification précoce de la matrice. L’analyse géochimique suggère que le hiatus de dépôt au sommet de la plateforme est lié à un ennoiement de la plate-forme. La diminution importante de la porosité (jusqu’à 10%) en dessous du contact gaz-eau suggère une phase majeure d’évolution de la porosité pendant et/ou après la mise en place des hydrocarbures. En modifiant considérablement la porosité et le réseau poreux, la diagenèse contrôle en grande partie l’architecture acoustique et sismique du réservoir. La calibration puits sismique a permis de mettre en évidence l’origine des réflecteurs sismiques. Ils se forment ainsi, dans la zone à gaz, à la limite entre deux unités diagénétiques ou résultent d’interférences entre les réflexions de la base et du sommet de ces intervalles. La lithification marine précoce des intervalles à coraux génère des réflecteurs de fortes amplitudes, continus, et assimilables à des lignes-temps chronostratigraphiques. En revanche, un réflecteur diachrone, recoupant la stratigraphie, est généré au niveau d’un contraste de porosité au voisinage du contact eau-hydrocarbure. Enfin, une méthode d’inversion pétrophysique basée sur une approche DEM (Differential Effective Medium theory) a été développée et appliquée sur les données de sismique 3D. Cette approche a permis de prédire de manière pertinente les hétérogénéités géologiques ayant une incidence sur les écoulements de fluide et la montée du niveau d’eau dans le réservoir. Fournissant un cadre géologique robuste à la caractérisation du réservoir de Yadana, la présente thèse apporte également des informations supplémentaires sur la compréhension des facteurs géologiques et environnementaux contrôlant les systèmes de carbonates isolés cénozoïques en Asie du Sud-Est. Ce travail met en évidence l’interdépendance existante entre la géologie et l’imagerie sismique et démontre que les caractérisations paléoenvironnementale et diagénétique sont essentielles à la fois en phase d’exploration, mais aussi en phase d’évaluation et de production d’hydrocarbures

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Le réservoir de gaz de Yadana est localisé en mer d'Andaman, au large des cotes de Birmanie et est en production depuis 1998. Le réservoir est une plateforme carbonaté d'âge Oligocène-Miocène scellé sous 1200 m de sédiments fluviatiles. Dans ce réservoir devenu mature, la prédiction des réserves ultimes d'hydrocarbures ainsi que la compréhension des mouvements d'eau dans le réservoir pendant la production sont des challenges majeurs pour les géologues pétrolier. La présente thèse propose de développer une méthode de travail permettant la construction d'un modèle réservoir détaillé qui prends en comptes diverses hétérogénéités. Ce travail est multidisciplinaire et multi-échelles et couvre à la fois des aspects de sédimentologie, de stratigraphie, de diagénèse, de géochimie, de pétrophysique, de géophysique et se base sur un large jeu de données incluant des données de roches, de diagraphies et de données sismiques.Fournissant un cadre géologique robuste pour la caractérisation du gisement du champ de Yadana, la thèse fournit des informations supplémentaires sur la compréhension des facteurs géologiques et environnementaux contrôlant les systèmes de carbonates isolés du Cénozoïque en Asie du Sud-Est.Ces travaux soulignent une nouvelle fois l’interdépendance existant entre la géologie et l’imagerie sismique et démontrent qu’une caractérisation géologique / géophysique intégrée des réservoirs carbonatés reste cruciale pour l’exploration, l’évaluation et la production de ressources en hydrocarbures.The Yadana gas field is located in the Andaman Sea, offshore Myanmar and producing gas since 1998. The reservoir is an isolated carbonate buildup, Miocene in age, sealed below 1200 m of siliciclastic sediments. Predicting the ultimate hydrocarbon resources and the water flows during the production has become a major challenge for such mature gas field. The PhD work involves the implementation of a methodology allowing the construction of a detailed reservoir architecture that accounts various types of heterogeneities. The work is multiscale and multidisciplinary, covering disciplines such as sedimentology, stratigraphy, diagenesis, geochemistry, rock physics, geophysics and based on a large and comprehensive dataset including, cores, well-logs, petrophysical measurements, production and 3D/4D seismic data. Providing a robust geological framework for the reservoir characterization of the Yadana field, the thesis gives further insights into the understanding of geological and environmental factors controlling Cenozoic isolated carbonate systems in South East Asia. This work highlights once again the interdependence existing between geology and seismic imaging and demonstrates that an integrated geological/geophysical characterization of carbonate reservoirs remains crucial for both the exploration, the evaluation and the production of hydrocarbon resource

Origin of seismic reflections in a carbonate gas field, Lower Miocene, offshore Myanmar

International audienc

Performance indices and selection of thin hard coatings on soft substrates for indentation and scratch resistance

A generic mechanical framework has been developed for assessing the indentation and scratch resistance of hard films on soft substrates. Analytical expressions for the critical loads leading to filmcracking or substrate yielding are proposed based on closed form plate bending models and on finite element simulations. These models lead to the definition of performance indices for the ranking of “hard-film-on-soft-substrate” systemswith respect to the resistance to indentation and scratch failure under the constraint of minimizing film thickness. These performance indices show that the hardest coating is not always the best choice and that other material properties of the film and the substrate have to be taken into account. An illustrative material property chart is proposed in order to compare the protective ability of some usual thin coatings. These results constitute a guide for the development of layered systems in order to avoid time consuming and expensive trial and error campaigns