Signification géodynamique des calcaires de plate-forme en cours de subduction sous l'arc des Nouvelles-Hébrides (Sud-Ouest de l'océan Pacifique)

Note présentée par Jean DercourtInternational audienceThe analysis of carbonates from New Hébrides Trench shows that three main épisodes of shallow water carbonate déposition occurred during Late Eocene,Late Oligocene-Early Miocène,Mio-Pliocene-Quaternary, controlled by eustatism and tectonic.L'analyse de carbonates issus de la fosse des Nouvelles-Hébrides a permis de reconnaître trois périodes favorables au développement de plates-formes(Éocène supérieur,Oligocène supérieur-Miocène inférieur,Mio-Pliocène-Quaternaire)contrôlé par l'eustatisme et la tectonique

Facies and faunal assemblage changes in response to the Holocene transgression in the Lagoon of Mayotte (Comoro Archipelago, SW Indian Ocean)

This paper documents the facies change in response to the Holocene transgression within five sediment cores taken in the lagoon of Mayotte, which contain a Type-1 depositional sequence (lowstand, transgressive and highstand deposits underlain by an erosive sequence boundary). Quantitative compositional analysis and visual examination of the bioclasts were used to document the facies changes. The distribution of the skeletal and non-skeletal grains in the lagoon of Mayotte is clearly controlled by (1) the rate and amplitude of the Holocene sea-level rise, (2) the pre-Holocene basement topography and (3) the growth-potential of the barrier reef during sea-level rise, and the changes in bathymetry and continuity during this period. The sequence boundary consists of the glacial karst surface. The change-over from the glacial lowstand is marked by the occurrence of mangrove deposits. Terrigenous and/or mixed terrigenous-carbonate muds to sandy muds with a mollusc or mollusc-ostracod assemblage dominate the transgressive deposits. Mixed carbonate-siliciclastic or carbonate sand to gravel with a mollusc-foraminifer or mollusc-coral-foraminifer assemblage characterize the early highstand deposits on the inner lagoonal plains. The early highstand deposits in the outer lagoonal plains consist of carbonate muds with a mollusc-foraminifer assemblage. Late highstand deposits consist of terrigenous muds in the nearshore bays, mixed terrigenous-carbonate sandy muds to sands with a mollusc-foraminifer assemblage on the inner lagoonal plains and mixed muds with a mollusc-foraminifer assemblage on the outer deep lagoonal plains. The present development stage of the individual lagoons comprises semi-enclosed to open lagoons with fair or good water exchange with the open ocean

Późnoalbskie - wczesno/środkowocenomańskie małżoraczki z Płaskowyżu Pólnocnej Galali (Egipt)

Middle Cretaceous ostracodes from two sections in the Northern Galala Plateau, western coastal Gulf of Suez (Egypt) are presented. 30 species have been recorded, of which 4 are new: Asciocythere galalaensis, Perissocytheridea ignota, Eocytheropteron pecteniferum and ?Spinoleberis calcalifera. Most of the species have been known so far from the Albian and/or Cenomanian of the South Tethys, especially the Near East. No species common for these ages from the North and South Tethys i.e. Africa and Europe, have been found. Ostracode associations probably show the late Albian to early/mid-Cenomanian age. The distribution is related to fluctuating conditions within the studied area, from euhaline to brackish/shallow water environments.Opracowano małżoraczki z osadów środkowej kredy, występujących na zachodnim brzegu Zatoki Suezkiej (Egipt). Małżoraczki pochodzą z dwóch odsłonięć (Ras El Abd i Khashm El Galala) (figs. 1—3) z osadów, których dolna część zaliczana jest do facji Piaskowców. Nubijskich, a górna część — do formacji Galala. W oparciu o otwornice Abd-Elshafy i Atta (w druku a, b) zaliczyli dolną część osadów do dolnego cenomanu natomiast górną do górnego cenomanu. Opisano 30 gatunków małżoraczków, w tym 4 nowe: Asciocythere galalaensis, Perissocytheridea ignota, Eocytheropteron pecteniferum i Spinoleberis calcalifera. Analiza ilościowego i jakościowego rozprzestrzenienia małżoraczków pozwoliła wydzielić 2 zespoły (jeden zdominowany przez Cytherella, drugi zdominowany przez Perissocytheridea), występujące przemiennie w badanych profilach (fig. 4) i pozwalające wydzielić 4 ekozony. Uważa się, że wydzielone ekozony są odbiciem fluktuacji w zasoleniu, dynamice i głębokości zbiornika; ekozona z wyraźną obecnością Cytherella odpowiada środowisku morskiemu (euhalinowemu), natomiast ekozona z Perissocytheridea charakteryzuje środowisko brakiczne. Wyróżnione ekozony pokrywają się w znacznym stopniu z biozonami wyróżnionymi w badanych odsłonięciach w oparciu o otwornice (Abd-Elshafy i Atta, w druku b). Małżoraczki sugerują jednak nieco starszy wiek osadów (figs. 2, 3), tj. górnoalbski — wczesno/środkowocenomański. Uznaje się, że ekozona 1 (w oparciu o małżoraczki zaliczona do albu) reprezentuje środowisko regresywne, natomiast ekozona 2 (?3) (na podstawie małżoraczków zaliczona do cenomanu) wyraża stopniowe tendencje w kierunku otwartego morza. Sugerowane tendencje w rozwoju środowiska środkowokredowego są w zgodzie z proponowanymi „krzywymi transgresji-regresji” dotyczącymi albu-turonu na Środkowym i Dalekim Wschodzie opracowanymi przez Riché i Přestat (1980). Z rozprzestrzenienia regionalnego badanych małżoraczków wynika, że są one ograniczone do Afryki północnej i Bliskiego Wschodu, wykazując większe podobieństwo do synchronicznych małżoraczków z tego drugiego obszaru. Należą one zatem do północnoafrykańsko-bliskowschodniej prowincji małżoraczkowej wydzielonej przez Babinot (1985)

Sensibilité de trois espèces de Chironomus (Diptera) à huit insecticides utilisés en démoustication

Des expérimentations de terrain en parcelles limitées ont permis, à partir de piégeages d'adultes, d'évaluer l'impact de huit insecticides sur des populations larvaires composées de 82 % de Chironomus salinarius, de 12 % de Chironomus halophilus et de Chironomus plumosus et 6 % d'autres espèces non identifées. Le diflubenzuron et les toxines de Bacillus thuringiensis H 14 et Bacillus sphaericus n'ont pas d'effet marqué aux doses détruisant les larves de moustiques. A ces mêmes doses, le fénitrothion, le téméphos et la deltaméthrine limitent fortement l'émergence. Le chlorpyrifos et le S 31183 (juvénoïde Sumitomo) sont très toxiques

Harnessing biopolyesters in the design of functional materials for biomedical applications

The present contribution illustrates the versatility of poly(3-hydroxyalkanoate)s (PHAs) in the design of a wide variety of biodegradable and/or biocompatible macromolecular architectures with controlled degradability. Firstly, functionalized PHAs were prepared from unsaturated PHAs. Pendant double bonds have been turned into carboxyl, hydroxyl, alkyne or epoxy groups. These reactive functions were used for further grafting hydrolyzable polylactide (PLA) or poly(ε-caprolactone) (PCL) as well as hydrophilic poly(ethylene glycol) (PEG). Additionally, block copolymers with a PLA, PCL or PEG segment have been prepared by ring-opening polymerization or "click" chemistry from a PHA oligomeric macroinitiator. Functional PHAs represent biodegradable aliphatic polyesters with many possibilities to tune physico-chemical characteristics, such as hydrophilicity and degradation rate, thus making the resulting materials suitable as devices for drug delivery or as scaffolds for tissue engineering. Herein, we address the recent trends in the synthesis of these polymeric materials and their applications in controlled drug delivery and tissue engineering

Correlation of sedimentary events during the Latest Cenomanian from the Basque Basin to the Castilian Ramp (Northern Spain)

Sedimentologic, biostratigraphic and geochemical analyses of the Late Cenomanian - Early Turonian series of the deep Basque Basin and of the Navarre-Cantabrian distal Ramp and Castilian proximal Ramp, allow: V to correlate sedimentary events such as the sedimentation of thin layers of organic matter-bearing laminated black shales in the Basque Basin and as the formation of glauconitic-pyritic bioturbated hardgrounds on the Navarre-Cantabrian and Castilian Ramps, 2) to date these events from the Archaeocretacea Zone, 3) to interpret them as evidence of anoxia in the basin and hypoxia on the ramps, and as results of major marine deepening and transgressionEstudios sedimentológicos, bioestratigráficos y geoquímicos de series de edad Cenomanense superior - Turonense inferior de la Cuenca profunda Vasca, de la Rampa distal Navarro-Cantábrica y de la Rampa somera Castellana han permitido: V correlacionar la deposición de arcillas negras laminadas (black shales) en la Cuenca Vasca con la formación de superficies endurecidas (hardgrounds) glauconíticas en las Rampas Navarro-Cantábrica y Castellana, 2) situar estos eventos en la Zona de Archaeocretacea, 3) interpretar dichos depósitos como indicadores de anoxia en la cuenca profunda y de hipoxia sobre las rampas, resultado de una profundi'¿ación y transgresión marina mayo

Photoactivable Surface of Natural Poly(3-hydroxybutyrate- co

International audienc

Photoinduced modification of the natural biopolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microfibrous surface with anthraquinone-derived dextran for biological applications

A straightforward and versatile method for immobilizing polysaccharides on the surface of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) electrospun fibers is developed with the objective of designing a new functional biomaterial having a significant effect on cell proliferation. The approach relies on a one-step procedure: UV grafting of a photosensitive dextran (AQ-Dext) on the surface of PHBHV fibers according to a "grafting onto" method, with the use of an anthraquinone derivative. The photografting is conducted through a photoinduced free radical process employing an anthraquinone-based photosensitizer in aqueous medium. Under appropriate conditions, AQ-Dext reacts with C-H sigma-bonds of the polymer substrate (PHBHV) to produce a semianthraquinone radical according to an H-abstraction reaction. This radical recombines together with the alkylradical (R-center dot) formed at the surface of PHBHV fibers via the oxygen atom of the anthraquinone photolinker. The photochemical mechanism of the AQ-Dext photolysis is entirely described for the first time by an electron spin resonance technique and laser flash photolysis. The modified PHBHV microfibrous scaffolds are extensively characterized by water contact angle measurements, XPS analysis and atomic force microscopy, confirming the covalent grafting of dextran on PHBHV fibers. Finally, a primary investigation demonstrates that dextran modified PHBHV fibers are permissive for optimized cell colonization and proliferation. The cell morphologies are described by SEM micrographs, revealing a significant affinity and favorable interactions for adherence of human mesenchymal stem cells (hMSCs) on scaffolds provided by dextran chemical structure. Moreover, the proliferation rate of hMSCs increases on this new functionalized biomaterial associated with a higher extra-cellular matrix production after 5 days of culture in comparison with native PHBHV fibers

Photoactivable Surface of Natural Poly(3-hydroxybutyrate-<i>co</i>-3-hydroxyvalerate) for Antiadhesion Applications

A green photoinduced method for the modification of a biodegradable and biocompatible polymer, Poly­(3-hydroxybutyrate-<i>co</i>-3-hydroxyvalerate) (PHBHV) has been successfully carried out using two types of monomers with potential antibacterial effects, i.e., 2-[(methacryloyloxy)-ethyl] trimethylammonium chloride (META) and an ampicillin-derived monomer. The photografting process is conducted through a photoinduced free-radical process employing a thiocarbamate-based photoinitiator in an aqueous medium. Under appropriate conditions, radicals are generated from the PHBHV surface, thus initiating the UV-mediated photopolymerization of methacrylate or methylacrylamide-derived monomers from the surface of PHBHV films. The photochemical mechanism of the thiocarbamate photolysis is entirely described by the electron spin resonance/spin-trapping technique and laser flash photolysis, and the modified-PHBHV films are extensively characterized by fluorescence experiments, water contact angle, and XPS measurements. Finally, a primary investigation is conducted to support the antibacterial property of the new functionalized films against <i>Escherichia coli</i> and <i>Staphylococcus aureus,</i> and their cytocompatibility with NIH-3T3 fibroblastic cells is evaluated