Graphene-based textured surface by pulsed laser deposition as a robust platform for surface enhanced Raman scattering applications

International audienceWe have developed a surface enhanced Raman scattering (SERS)-active substrate based on gold nanoparticles-decorated few-layer (fl) graphene grown by pulsed laser deposition. Diamond-Like Carbon film has been converted to fl-graphene after thermal annealing at low temperature. The formation of fl-graphene was confirmed by Raman spectroscopy, and surface morphology was highlighted by scanning electron microscopy. We found that textured fl-graphene film with nanoscale roughness was highly beneficial for SERS detection. Rhodamine 6G and p-aminothiophenol proposed as test molecules were detected with high sensitivity. The detection at low concentration of deltamethrin, an active molecule of a commercial pesticide was further demonstrated

Stratigraphic records and variability of incised valleys and estuaries along French coasts

International audienceSome of the striking results of the papers published in the special publication "French Incised valleys, estuaries and lagoons" of the Bulletin de la Société géologique de France are presented and compared. The selection of papers within this volume focuses exclusively on the recent progress made on modern French incised valleys, estuaries and lagoons around the coasts of France. Those papers together with abundant papers recently published on modern French incised valleys provide new insights for the knowledge on these sedimentary systems. The large amount of new results obtained is indebted to an extensive exploration within a large variety of estuaries, lagoons and coastal areas, from macrotidal tide-dominated, to microtidal wave-dominated, with also meso- to macrotidal mixed tide- and wave-dominated estuaries. These data allow comparing incised valleys within the same setting of tectonically stable and sediment starved margins, but showing contrasted conditions of hydrodynamics, sediment supply and bedrock control. At a stratigraphic level, sea-level variation is the main parameter controlling incised valley formation and sediment fill. The first-order controlling factor explaining the observed variations in valley fills is hydrodynamics. Three valley-fill categories are highlighted: tide-dominated, mixed tide-and-wave and wave-dominated, that match the classification based on hydrodynamics and morphology of present-day estuaries or lagoons. The second-order controlling factor explaining the observed variations in valley fills is the antecedent morphology of the bedrock, which in turn controls hydrodynamics and sediment supply. Finally, a promising result is the demonstration of the potential of incised valley fills to record high frequency environmental changes related to climate events and human activities

The Bonifacio Formation (Miocene of corsica): transition from a wave- to tide-dominated coastal system in mixed carbonate-siliciclastic setting

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Transition tempête-tidal dans un système côtier mixte carbonaté clastique: l'exemple de la formation miocène de Bonifacio (Corse du Sud)

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Synthesis of large area graphene layers by pulsed laser deposition

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Irradiance influence on the multicolor photochromism of mesoporous TiO2 films loaded with silver nanoparticles

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From accretion to forearc basin initiation: The case of SW Ecuador, Northern Andes

International audienceThe SW of Ecuador offers a great opportunity to study the long-term behavior of an almost entire forearc system, from the external accretionary prism to the landward limit of the forearc basin. A combination of field observations, LA-ICP-MS UPb dating on zircon and interpretation of different vintages of unpublished industrial seismic records are used to study the evolution of the forearc system of SW Ecuador including the accretionary prism and the forearc depocenter. The youngest dates, obtained from UPb dating on zircon grains believed to be derived from the arc, define the best estimate for the age of sedimentation and permits a clear description of the temporal and spatial evolution of the accretionary, post accretionary and forearc basin series between 60 Ma and 10 Ma. This reinforces the idea that forearc sediments can be dated by UPb on zircon provided that the arc is active at the moment of sedimentation. The Azúcar Formation reflects the accretion of SW Ecuador against the South American continental margin from 61 Ma to 55 Ma. This event is post-dated by the formation of an accretionary prism which may have started at circa 55 Ma. Deformation of the accretionary prism may have been less active during sedimentation of the Ancón Group from ~54 Ma (?) to ~40 Ma which shows evidence of normal faulting and other extensional processes. The transition from the Azúcar Formation to the Ancón Group is marked by a significant decrease of the topographic profile, which in turn resulted in sedimentary series that shallow upwards. The forearc basin sensu strictu develops coevally with the uplift of the outer forearc high (Estancia Hills) and the sedimentation of the Zapotal Formation at 32–30 Ma; the latest marking a significant differentiation in the sedimentary style of the area to shallower and even continental environments. From 30 Ma to 10 Ma the forearc basin was defined by shallow water deposits, progressively influenced by tidal dynamics, most likely related to a protected triangular bay symbolizing the shape of the forearc basin. Evidence presented here suggests the existence of a stable outer forearc high limiting the forearc depocenter for at least 20 My and creating, at least in part, the accommodation necessary for an ~3 km thick forearc sedimentary package. The architecture of SW Ecuador is typical of a forearc basin setting including an accretionary prism and an outer forearc high such as those observed in the Kumano (Japan) and the Coast Range and Great Valley basins (USA). The Estancia Hills may correspond to one of the best preserved exposures of an ancient outer forearc high worldwide

Etude de la variabilité climatique à haute résolution dans des sédiments de l’Atlantique Nord

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