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In this article, STEM-EELS methodology is described to investigate the composition of sensitive crystalline Silicon/amorphous aluminum oxide (c-Si/a-AlOx) interface of an a AlOx/amorphous hydrogenated silicon nitride (a-AlOx/a-SiNx:H) passivation stack of a c-Si solar cell. In this stack, a-AlOx has the distinctive characteristic to provide both chemical and field effect passivation, which need further research to be more controlled in order to improve solar cell efficiency. a-AlOx is known to be unstable under the electron-beam, so we first present a detailed study on the electron-beam radiation damage to c-Si/a-AlOx interface. This interface can indeed undergo several electron-beam irradiation damage like sputtering, knock-on or radiolysis if precautions are not taken. Radiolysis damage has been found to be the dominant radiation damage. Thus, several STEM-EELS acquisition parameters like acceleration voltage, electron dose and scan orientation were taken into account and modified to limit this radiolysis damage. Once the irradiation was limited, STEM-EELS investigation was conduct using DualEELS on the Si and Al L2,3 and OK edge fines structures. The interface was found to be composed of a-SiOx and non-stoichiometric aluminum silicate with a predominance of tetrahedrally coordinated Al in its first layer.

International audience; CuO is an attractive photocatalytic material for water splitting due to its high earth abundance and low cost. In this paper, we report the deposition of CuO thin films by sol–gel dip-coating process. Sol deposition has attractive advantages including low-cost solution processing and uniform film formation over large areas with a fairly good control of the film stoichiometry and thickness. Pure CuO phase was obtained for calcination temperatures higher than 360 °C in air. The CuO photocurrents for hydrogen evolution depend on the crystallinity and the microstructure of the film. Values of −0.94 mA cm−2 at pH = 8 and 0 V vs. RHE were achieved for CuO photoelectrodes annealed at 400 °C under air. More interestingly, the stability of the photoelectrode was enhanced upon the sol–gel deposition of a TiO2 protective layer. In this all sol–gel CuO/TiO2 photocathode, a photocurrent of −0.5 mA cm−2 is achieved at pH = 7 and 0 V vs. RHE with a stability of ~100% over 600 s.

International audience; To accelerate the conversion to more sustainable lubricants, there is a need for an improved understanding of the adsorption at the solid/liquid interface. As a first step, the DFT computed adsorption energies can be used to screen the ability of additives to cover a surface. Analogously to what has been found in catalysis with the universal scaling relations, we investigate here if a general universal ranking of additives can be found, independently of the surface considered. We divided our set of 25 diverse representative molecules into aprotic and protic molecules. We compared their adsorption over alumina and hematite, which are models of surface oxidized aluminum and steel, respectively. The adsorption energy ranking of our set is not strongly affected by alumina hydration. In contrast, adsorption on hematite is more strongly affected by hydration since all exposed Fe Lewis acid sites are converted into hydroxylated Brønsted basic sites. However, the ranking obtained on hydrated hematite is close to the one obtained on dry alumina, paving the road to a fast screening of additives. In our library, protic molecules are more strongly adsorbed than non-protic molecules. In particular, methyl and dimethyl phosphates are the most strongly adsorbed ones, followed by Nmethyldiethanolamine, succinimide and ethanoic acid. Additives combining these functional groups are expected to strongly adsorb at the solid/liquid interface and, therefore, likely to be relevant components of lubricant formulations.

International audience; Photovoltaic power stations are developing worldwide as they emit no greenhouse gases while producing electricity. In France, industries such as Total plan to install such stations in fields surrounding their chemical and refining plants. The risk analyses performed for these plants often highlighted Unconfined Vapor Cloud Explosions scenarios, related to heavy gases releases, for which characteristic overpressure effect distances were computed The present work aims at quantifying the impact of the presence of a photovoltaic power station in a potential flammable cloud. It is nevertheless limited to a station geometry provided by Total. The problem is not straightforward as two main physical trends appear: flame acceleration due to panels obstruction and flame extinction when the flame reaches the top of the flammable cloud. It has first to be determined if explosion runaway is possible, this one due to the obstacles repetition on the flame path. Then, characteristic overpressure effects distances can be computed for photovoltaic power plants of any size. To this goal, a CFD-based method is proposed and detailed. The open-source CFD code OpenFoam is used as well as phenomenological considerations for computing characteristic overpressure effects distances.

Pool evaporation is a major source of flammable vapour clouds. Predicting the evaporation rate of a liquid hydrocarbon pool is therefore a key issue of dispersion modelling for safety concerns. This paper presents small- and medium-scale experiments of pool evaporation carried out with liquid hydrocarbons (pentane, heptane), hydrocarbon “gasoline-like” mixtures and gasoline. Liquid mass loss was measured and the evaporation rate deduced with its evolution in time. Other observations are highlighted, regarding the evolution of liquid temperatures, mixture compositions, and scale effects like the influence of pool length on surface evaporation rate. Comparisons with well-known correlations are then shown. The authors finally suggest a new semi-empirical correlation with a set of parameters fitted on the performed experiments.

International audience; As renewables are progressively displacing thermal plants in the power generation scene worldwide, the vocation of stationary Gas Turbines (GT) is deeply evolving. In this irreversible move GT plants are called upon to become cycling units with increasingly variable load profiles. This is dictated by the need to compensate for the fluctuations of renewable energy sources and secure the spinning reserve that is indispensable for the stability of the grids. This new scenario creates a serious challenge for gas turbine designers and operators in terms of investment policy, plant management and equipment lifetime. Indeed, operating a gas turbine at part, variable load requires reducing its firing temperature and possibly its air flow. While part load operation entails efficiency losses with respect to the full load mode, load variations cause maintenance penalties due the premature component ageing tied namely with thermal and low cycle fatigue effects on machine materials. As far as efficiency is concerned, an exergy analysis of a contemporary, air-based Brayton cycle is useful for quantifying and comparing the losses incurred by the various engine components. Such study reveals the high sensitivity of compressor efficiency to load decreases. Among possible countermeasures , heating the air at the compressor intake represents a simple mitigation measure, as it enables reducing the air flow rate while preserving to some extent the efficiency of the compressor and consequently GT efficiency.

New high-quality multibeam and high-resolution seismic data reveal new observations on sediment transfer and distribution and margin morphometrics in the uppermost slope of Northeastern Little Bahama Bank between 20 and 300 m water depth. The echofacies/backscatter facies show an alongslope sediment distribution forming successive strips. The upper part of the uppermost slope corresponds to the alternation of several submerged coral terraces and escarpments that could be related to Late Quaternary sea-level variations. The terraces could either be related to periods of stagnating sea-level or slow-down in sea-level change and therefore increased erosion by waves, or periods of accelerated sea-level rise since the Last Glacial Maximum. Terraces could therefore be related to coral construction and drowing. The medium part corresponds to the marginal escarpment, a steep cemented area. The lower part of the uppermost slope shows a discontinuous Holocene sediment wedge with varying thickness between 0 and 35 m. It is separated from the upper part by a zone of well-cemented seafloor associated with the marginal escarpment. Passing cold fronts result in sediment export caused by density cascading. The associated sediment fall-out and convective sedimentation can generate density currents that form this wedge and eventually flow through linear structures on the upper slope. The survey reveals the presence of recently active channels that extend over the entire uppermost slope and interrupt the wedge. The channels connect shallow tidal channels to submarine valleys connected to the proximal part of canyons. They directly feed the canyons with platform-derived sediment forming low-density turbidity currents and could supply the deepest part of the system with coarse-grained sediment directly exported from the carbonate platform.

International audience; Understanding processes of formation of accretionary wedges requires studying young and well preserved examples. The Lengguru wedge (West Papua) is younger than 10 Myr and is a result of oblique and fast subduction (11 cm/yr) of the Bird's Head (a part of the Australian margin beneath the Melanesian Arc). Thus, the rapid formation of this wedge (actually a Fold and Thrust Belt) may be attributed to a single tectonic event. High pressure (HP) metabasic and metasedimentary rocks have been discovered in the core of the wedge in the Wandamen peninsula. Locally, these rocks are overprinted by migmatization during the decompression. Field relationships indicate that migmatites and anatectic leucogranite crosscut the HP metamorphic rocks. This paper reports characterization of petrology and thermobarometry of metasediments and metabasic samples, all included in a former mélange-type rock association, as well as geochronology of metasediments. Pressure–Temperature (P–T) conditions highlight two stages of metamorphism within a small time bracket. In metasediments, a first stage of relatively HP (~ 13–17 kbar) is observed as attested by a first paragenesis of garnet–kyanite–phengite. Garnet, kyanite and phengite are then destabilized in favor of biotite during the decompression (5–12 kbar and > 550 °C). Late fractures filled with chlorite and a second generation of white mica crosscut the foliation (< 7 kbar and 500–600 °C). In metabasic rocks, the peak of pressure is reached from 17 to 23 kbar and from 700 to 800 °C. Geochronological study was conducted using U–Pb dating (LA-MC-ICPMS) on zircons from the metasedimentary and migmatitic rocks. Some zircon cores often present high Th/U ratio typical for magmatic origin, as confirmed by trace element signature of metasediments, and recorded ages older than 300 Ma, witness of the activity of a volcanic arc on the former margin of the Australian craton. Most other zircons present a low Th/U ratio attesting their metamorphic origin, confirmed by inclusions of kyanite. The metamorphic zircons are dated between 5.61 ± 0.04 Ma and 8.1 ± 1.1 Ma. These very young metamorphic ages attest for a rapid subduction and exhumation event.

International audience

International audience; The amalgamation of Gondwana and its subsequent fragmentation has been a subject of several studies over the past five decades, yet the very important question of the initial geometry of the supercontinent remains enigmatic. Current reconstruction models of the Indian Ocean are characterized by large gaps, overlaps and misfits of major structural and Cratonic bodies in their fit, and positions of tectonic blocks that are inconsistent with field observations, a phenomenon sustained by inadequate data, long standing debates and a lack of consensus on the nature of major structures and basins in the ocean. Past attempts to reconstruct the initial fit of the ocean has led to varied and complex models, with their own logic and different geographical limits, whose validity and underlying assumptions require testing in the light of current global geological and geophysical data. Our analysis of these models and their consequences on the continental passive margins brings to the fore critical scientific questions and the incoherencies that exist between them. This paper presents a compressive study of the structure of the Precambrian basement, Paleozoic marginal and rift basins of the plates constituting the Indian Ocean, examining the architecture and geochronological composition of their composing Cratons and crustal blocks, and delineating important structural markers to juxtapose them in full-fit reconstructions. We introduce a new holistic model from Gondwana’s initial geometry to Chron 34, achieved through a combination of onshore and offshore geological and geophysical data. Our new model is coherent with current data interpretations of major structures across the Indian Ocean. Consistent with the interpretation of the Beira High as continental crust, and recent seismic refraction interpretation of the Pamela MOZ3-5 expedition in the Northern Mozambique Ridge and Northern Natal Valley. The model also permits full extent of major cratonic, volcanic and sedimentary structures within the supercontinent, and presents a new synthesis upon which further work may be projected.

The ecological and economic importance of fish act as a brake on the development of chemical dispersants as operational instruments following oil spills. Although a valuable and consistent body of knowledge exists, its use in spill response is limited. The objective of the present study was to increase current knowledge base to facilitate the translation of published data into information of operational value. Thus we investigated the dose-response relationship between dispersant-treated oil exposure and ecologically relevant consequences by combining laboratory and field experiments. Effects were examined over almost a year using juveniles of the slowly growing, commercially important European sea bass (Dicentrarchus labrax). A reliable interpretation of biomarker responses requires a complete knowledge of the factors likely to affect them. Interpopulational variability is of particular importance in environmental impact assessment because biomarker responses from a population collected in an impacted area are classically compared with those collected in a clean site. Our study revealed no effect of the exposure to dispersant-treated oil on fish hypoxia tolerance and temperature susceptibility at 1 and 11 mo post exposure. Similarly, no effect of the exposure was observed on the ability of the fish to cope with environmental contingencies in the field, regardless of the dose tested. Thus we feel confident to suggest that a 48-h exposure to chemically treated oil does not affect the ability of sea bass to cope with mild environmental contingencies. Finally, investigation of interpopulation variability revealed large differences in both hypoxia tolerance and temperature susceptibility among the 2 populations tested, suggesting that this variability may blur the interpretation of population comparisons as classically practiced in impact assessment. Environ Toxicol Chem 2019;38:210-221. © 2018 SETAC.

Selective laser ablation of dielectric layers on crystalline silicon wafers was investigated for solar cell fabrication. Laser processing was performed on Al 2 O 3 , and bi-layers Al 2 O 3 /SiN X :H with a nanosecond UV laser at various energy densities ranging from 0.4 to 2 J cm −2 . Ablation threshold was correlated to the simulated temperature at the interface between the dielectric coatings and the silicon substrate. Laser-induced damage to the silicon substrate was evaluated by time-resolved photoluminescence. The minority carrier lifetime deduced from time-resolved photoluminescence was related to the depth of the heat affected zone in the substrate.

International audience; Rifts are often associated with ancient traces of hotspots, which are supposed to participate to the weakening of the lithosphere. We investigated the expected past trajectories followed by three hotspots (Afar, East-Africa and Lake-Victoria) located around the Red Sea. We used a hotspot reference frame to compute their location with respect to time, which is then compared to mantle tomography interpretations and geological features. Their tracks are frequently situated under continental crust, which is known to strongly filter plume activity. We looked for surface markers of their putative ancient existence, such as volcanism typology, doming, and heat-flow data from petroleum wells. Surface activity of the East-Africa hotspot is supported at 110 Ma, 90 Ma and 30 Ma by uplift, volcanic activity and rare gas isotopic signatures, reminiscent of a deep plume origin. The analysis of heat-flow data from petroleum wells under the Arabian plate shows a thermal anomaly that may correspond to the past impact of the Afar hotspot. According to derived hotspot trajectories, the Afar hotspot, situated (at 32 Ma) 1000 km north-east of the Ethiopian–Yemen traps, was probably too far away to be accountable for them. The trigger of the flood basalts would likely be linked to the East-Africa hotspot. The Lake-Victoria hotspot activity appears to have been more recent, attested only by Cenozoic volcanism in an uplifted area. Structural and thermal weakening of the lithosphere may have played a major role in the location of the rift systems. The Gulf of Aden is located on inherited Mesozoic extensional basins between two weak zones, the extremity of the Carlsberg Ridge and the present Afar triangle, previously impacted by the East-Africa hotspot. The Red Sea may have opened in the context of extension linked to Neo-Tethys slab-pull, along the track followed by the East Africa hotspot, suggesting an inherited thermal weakening.

National audience; Hybrid organic-inorganic halide perovskites {ABX3 with A = CH3NH3 (MA), NH2CHNH2 (FA), Cs, Rb ; B = Pb and X = Cl, Br or I} have become a very important class of materials for low-cost photovoltaic applications in the past few years. In 2016, the efficiency of a single-junction perovskite solar cell has reached 22.1% , getting close to the average efficiency of Al-BSF silicon cells in a short amont of time. Nevertheless, many issues are still worthwhile working on to obtain a non-toxic stable photovoltaic device. For instance, the presence of lead has led the community to search for alternative materials, which are both stable, earth abondant and environment-friendly. Replacing Pb with elements from the same periodic group (Sn, Ge…) has been widely investigated, but the instability of Sn 2+ and Ge 2+ based compounds is a serious obstacle for the development of lead-free architectures. More recently, double halide perovskites {A2B I B III X6 with A = Cs, MA ; B I = K, Ag, In, Tl etc ; B III = Bi, Al, Ga, In etc and X = Cl, Br etc} have opened a new path for the study of lead free perovskites systems .

International audience; Although long-term evolutions of isolated shallow-water carbonate platforms and demise episodes leading to guyot formation have been the subject of numerous studies during the last decades, their driving processes are still the subject of active debates. The Mozambique Channel (SW Indian Ocean) is characterized by several flat-topped seamounts ranging from 11°S to 21°S in latitudes. Based on a comprehensive geomorphologic study and on dredged samples analysis, we show that these features correspond to tropical isolated shallow-water carbonate platforms. Coupling strontium isotopy and foraminifera biostratigraphy, well-constrained chronostratigraphy results indicate that shallow-water carbonate production started in the Mozambique Channel during distinct Cenozoic periods ranging from Paleocene to Early Miocene. Our data also demonstrate that these carbonate platforms were subsequently characterized by different evolutions locally marked by tectonic and rejuvenated volcanism. While some of them kept developed until present days, forming modern carbonate systems, some others were drowned during Late Neogene and subsided to form guyots. Although different factors can be discussed, tectonic and volcanism appear as good potential triggers for demise episodes during Late Miocene-Early Pliocene times. Chronology and location of this geodynamical activity tend to emphasize influence of East African rift system until southern Mozambique Channel.

International audience; The post-rift (20-0 Ma) vertical movements of the Provence Basin (West Mediterranean) are quantified on itsboth conjugate (the Gulf of Lion and the West Sardinia) margins. This work is based on the stratigraphic studyof sedimentary markers using a large 3D grid of seismic data, correlations with existing drillings and refractiondata. The post-rift subsidence is measured by the direct use of sedimentary geometries analysed in 3D [Gorini etal., 2015; Rabineau et al., 2014] and validated by numerical stratigraphic modelling. Three domains were found:on the platform (1) and slope (2), the subsidence takes the form of a seaward tilting with different amplitudes,whereas the deep basin (3) subsides purely vertically [Leroux et al., 2015a]. These domains correspond to thedeeper crustal domains respectively highlighted by wide angle seismic data. The continental crust (1) and thethinned continental crust (2) are tilted, whereas the intermediate crust, identified as lower continental exhumedcrust [Moulin et al., 2015, Afhilado et al., 2015] (3) sagged. The post-break-up subsidence re-uses the initial hingelines of the rifting phase. This striking correlation between surface geologic processes and deep earth dynamicprocesses emphasizes that the sedimentary record and sedimentary markers is a window into deep geodynamicprocesses and dynamic topography.Pliocene-Pleistocene seismic markers enabled high resolution quantification of sediment budgets over the past6 Myr [Leroux et al., in press]. Sediment budget history is here completed on the Miocene interval. Thus, thecontrolling factors (climate, tectonics and eustasy) are discussed.Afilhado, A., Moulin, M., Aslanian, D., Schnürle, P., Klingelhoefer, F., Nouzé, H., Rabineau, M., Leroux,E. & Beslier, M.-O. (2015). Deep crustal structure across a young 1 passive margin from wide-angle and reflectionseismic data (The SARDINIA Experiment) - II. Sardinia’s margin. Bull. Soc. géol. France, 186, ILP Spec. issue,4-5, 331-351.Gorini, C., Montadert, L., Rabineau, M., (2015) New imaging of the salinity crisis: Dual Messinian lowstandmegasequences recorded in the deep basin of both the eastern and western Mediterranean, Marine and PetroleumGeology (2015), doi: 10.1016/j.marpetgeo.2015.01.009.Leroux, E., Aslanian, D., Rabineau, M., Moulin, M., Granjeon, D., Gorini C. & Droz, L. (2015a). Sedimentarymarkers in the Provençal basin (Western Mediterranean): a window into deep geodynamic processes. Terra Nova,27(2), 122-129.Leroux, E., Rabineau, M., Aslanian, D., Gorini, C., Molliex, S., Bache, F., Robin, C., Droz, L., Moulin, M.,Poort, J., Rubino, J.-L. & Suc, J.P. (2016, in press). High resolution evolution of terrigenous sediment yieldsin the Provence Basin during the last 6 Ma: relation with climate and tectonic. Basin Research, xx, xx-xx (ID:4759575-1545130).Moulin, M., Klingelhoefer, F., Afiladho, A., Aslanian, D., Schnürle, P., Nouze, H., Beslier, M.-O. & Feld, A.(2015). Deep crustal structure across an young passive margin from wide-angle and reflection seismic data (TheSARDINIA Experiment) - I. Gulf of Lion’s margin, Bull. Soc. géol. France., 186, ILP Spec. issue, 4-5,309-330.Rabineau, M., Leroux, E., Aslanian, D., Bache, F., Gorini, C., Moulin, M., Molliex, S., Droz, L., Reis, T. D.,Rubino, J.-L., Guillocheau, F. & Olivet, J.-L. (2014). Quantifying subsidence and isostatic readjustment usingsedimentary markers (example in the Gulf of Lion). Earth and Planetary Science Letters, 388, 1-14

International audience; Both surface photovoltage and photocurrent enable to assess the effect of visible light illumination on the electrical behavior of a solar cell. We report on photovoltage and photocurrent measurements with nanometer scale resolution performed on the cross section of an epitaxial crystalline silicon solar cell, using respectively Kelvin probe force microscopy and conducting probe atomic force microscopy. Even though two different setups are used, the scans were performed on locations within 100-μm distance in order to compare data from the same area and provide a consistent interpretation. In both measurements, modifications under illumination are observed in accordance with the theory of PIN junctions. Moreover, an unintentional doping during the deposition of the epitaxial silicon intrinsic layer in the solar cell is suggested from the comparison between photovoltage and photocurrent measurements.

This paper presents a prospective study for identifying selected parameters of the modified Cam-Clay model representing the behaviour of heavy oil reservoirs. The first part shows that the plastic compressibility, which controls the main recovery mechanism of such reservoirs, can be accurately determined, simultaneously with other parameters, by an inverse analysis of pressure–strain curves. The conditions of the identification procedure mainly involve two tests conducted under different drainage conditions or at different strain rates. The numerical study also establishes the sequence of an original in situ experimental program, in which three dilatometer tests at a relatively great depth (several hundreds of metres) were carried out. The comparison of the experimental data with the numerical computations reveals a significant over-consolidation ratio which does not allow the plastic compressibility to be determined but supports the findings regarding the geological erosion of the site. Copyright © 2006 John Wiley & Sons, Ltd.

International audience

International audience; The development of a hydrogen economy will need a transportation infrastructure to deliver hydrogen from production sites to end users. For the specific case of hydrogen, pipelines networks compete with other hydrogen carriers: compressed gas trucks and liquid cryogenic trucks. In this paper, we deal with the determination of the temporal deployment of a new hydrogen transportation infrastructure. Starting from the expected final horizon pipelines network, we propose a backward heuristic approach. The proposed approach is illustrated on a French regional hydrogen transportation network tacking into account two scenarios for hydrogen penetration into the fuel markets. We showed that for the mid term perspective and low market share, the trucks are the most economical options. However, for the long term, the pipeline option is considered as an economical viable option as soon as the hydrogen energy market share for the car fueling market reaches 10%.

The number and impact of extreme natural events year after year are amplified. Complex systems must be protected against their violence. The process of risk management is a common methodology to different industrial sectors: characterization of extreme natural events, followed by introduction of devices to prevent the impact of extreme natural events, and to manage the crisis. Although legal texts are a common framework, the definition of these devices is specific to each industry that must adapt to the specificity of its activities and their own type of risk. This results in a lack of homogeneity which may limit the effectiveness of the device as a whole., Le nombre et l’impact des événements naturels extrêmes s’amplifient d’année en année. Les systèmes complexes doivent être protégés face à leur violence. La démarche de maîtrise des risques relève d’une méthodologie commune aux différents secteurs industriels : caractérisation des événements naturels extrêmes, suivie d’une mise en place de dispositifs visant à prévenir l’impact des événements naturels extrêmes, et à gérer la crise. Même si les textes légaux sont un cadre commun, la définition de ces dispositifs est propre à chaque secteur d’activité qui se doit de les adapter à la spécificité de son domaine et de sa propre typologie de risques. Il en résulte un manque d’homogénéité qui peut limiter l’efficacité du dispositif dans sa globalité.

International audience; This work considers the problem of the optimal design of an hydrogen transmission network. This design problem includes the topology determina tion and the pipelines dimensioning problem. We define a local search method that simultaneously looks for the least cost topology of the network and for the optimal diameter of each pipe. These two problems were generally solved separately these last years. The application to the case of development of future hydrogen pipeline networks in France has been conducted at the local, regional and national levels. We compare the proposed approach with another using Tabu search heuristic.