Éditeur(s) : Université Paris 7 – Denis Diderot
Résumé : Sea surface salinity (SSS) influences numerous oceanic phenomena, for instance surface water ventilation, deep water formation and thermohaline circulation. SSS also controls some ocean-atmosphere coupled processes, such as the intensity of freshwater flux and the penetration of heat flux and turbulence. Salinity is more difficult to measure than temperature from in situ surveys, which results in 20 times less data being currently available. Moreover, sea surface temperature (SST) is routinely estimated from satellites, which is not possible yet for SSS. Two space missions will fill this gap soon: SMOS from the European Space Agency and Aquarius/SAC-D from NASA and CONAE. To contribute to the SMOS project, we propose a method for estimating SSS from current satellite observations and for studying the mechanisms governing its variability. We developed a simplified model of the ocean mixed layer, based on the "slab mixed layer" formulation (Frankignoul et Hasselmann, 1977). This 2D horizontal model is implemented over the global ocean, using a near 100 km resolution, and integrated during a climatological year. Air-sea fluxes are taken from the ECMWF meteorological model (ERA40 reanalysis) and the surface currents are provided by altimeter data (SSALTO-DUACS analysis). The mixed layer depth (MLD) is derived from SST observations, using an original inversion technique. The MLD fields obtained from this inversion are well correlated to in situ estimates. This effective depth represents the air-sea fluxes penetration and ensures consistency between fluxes, les currents and SST. We first validate the simulation through examination of the heat balance in north-eastern Atlantic, by comparing to measurements and models from the POMME experiment. Then we study the salinity balance in the global domain, in terms of its geographical distribution and seasonal evolution. Equilibrium between the various processes appears generally more complex than for temperature. Noteworthy, the role of atmospheric flux is less predominant (22%), while geostrophic advection (33%) and diapycnal mixing (22%) contribute more strongly. Our results indicate this model succeeds in reconstructing SSS variability over most of the oceans. Daily SSS variations are also simulated, whereas they are not represented in current observed data at a global scale. Owing to its simplicity and fast computation, the model will be useful to the SMOS mission. It can help for the measurement calibration/validation and provide a first guess estimate to the sophisticated algorithm required for SSS restitution.
La salinité de surface des océans (SSS) influence de nombreux phénomènes océaniques, parmi lesquels la ventilation des eaux de surface, la formation d'eaux profondes et la circulation thermohaline. Elle détermine aussi certains processus couplés océan-atmosphère, notamment l'intensité du flux d'eau douce, la pénétration du flux de chaleur et de la turbulence. La mesure in situ de salinité est plus compliquée que celle de température, si bien qu'on dispose actuellement de 20 fois moins de données pour cette propriété. De plus, la température de surface (SST) est couramment estimée par satellite, ce qui n'est pas encore le cas de la SSS. Deux missions spatiales vont prochainement combler cette lacune : le satellite SMOS de l'Agence Spatiale Européenne et le satellite Aquarius/SAC-D de la NASA et de la CONAE. En préparation du projet SMOS, nous proposons une méthode pour estimer la SSS à partir des observations satellitaires actuelles et étudier les mécanismes de sa variabilité. Nous avons développé un modèle simplifié de couche mélangée océanique, basé sur la formulation "slab mixed layer" (Frankignoul et Hasselmann, 1977). Ce modèle 2D horizontal est implémenté sur l'océan global, avec une résolution proche de 100 km, et intégré au cours d'une année climatologique. Les flux air-mer proviennent du modèle météorologique ECMWF (réanalyse ERA40) et les courants de surface sont issus de l'altimétrie (analyse SSALTO-DUACS). La profondeur de la couche mélangée (MLD) est dérivée des observations de SST, grâce à une technique d'inversion originale. La MLD obtenue par inversion est bien corrélée aux estimations basées sur des données in situ. Cette profondeur effective représente la pénétration des flux air-mer et assure la cohérence entre les flux, les courants et la SST. La simulation est d'abord validée en examinant le bilan de chaleur dans l'Atlantique Nord-Est, par comparaison aux mesures et aux modèles de l'expérience POMME. Puis le bilan de salinité est étudié dans le domaine global, en termes de distribution géographique et d'évolution saisonnière. L'équilibre entre les différents processus est généralement plus complexe que pour la température. Notamment, le rôle du flux atmosphérique est moins prépondérant (22%), tandis que l'advection géostrophique (33%) et le mélange diapycnal (22%) contribuent fortement. Nos résultats montrent que ce modèle parvient à restituer la variabilité de la SSS sur la majeure partie des océans. Le modèle simule aussi les variations journalières de SSS, qui ne sont pas représentées à l'échelle globale dans les observations actuelles. Grâce à sa simplicité et à sa rapidité, le modèle pourra être utile dans le cadre de SMOS. Il pourra aider à la calibration/validation de la mesure et fournir une estimation a priori pour l'algorithme complexe nécessaire à la restitution de la SSS.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/these-2302.pdf
http://archimer.ifremer.fr/doc/00000/2302/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : 51 pages; 15figures; 3 tables, accepted for publication in PloS ONE
International audience
We present a study about AFM imaging of living, moving or self-immobilized, bacteria in their genuine physiological liquid medium. No external immobilization protocol, neither chemical nor mechanical, was needed. For the first time, the native gliding movements of Gram-negative Nostoc cyanobacteria upon the surface, at speeds up to 900microns/h, were studied by AFM. This was possible thanks to an improved combination of a gentle sample preparation process and an AFM procedure based on fast and complete force-distance curves made at every pixel, drastically reducing lateral forces. No limitation in spatial resolution or imaging rate was detected. Gram-positive and non-motile R. wratislaviensis bacteria were studied as well. From the approach curves, Young modulus and turgor pressure were measured for both strains at different gliding speeds and are ranging from 20±3 to 105±5MPa and 40±5 to 310±30kPa depending on the bacterium and the gliding speed. For Nostoc, spatially limited zones with higher values of stiffness were observed. The related spatial period is much higher than the mean length of Nostoc nodules. This was explained by an inhomogeneous mechanical activation of nodules in the Nostoc. We also observed the presence of a soft extra cellular matrix (ECM) around the Nostoc. Both strains left a track of polymeric slime with variable thicknesses. For R. wratislaviensis, it is equal to few hundreds of nanometers, likely to promote its adhesion to the sample. While gliding, the Nostoc secretes a slime layer the thickness of which is in the nanometer range and increases with the gliding speed.
ISSN: 1932-6203

hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765v3/document
https://hal.archives-ouvertes.fr/hal-00769765/file/REsubmission_In-situ_determination_Dhahri_Plos_One_R2_Hal.pdf

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
This article is intended as a preliminary report on the implementation of a finite volume multilevel scheme for the discretization of the incompressible Navier-Stokes equations. As is well known, the use of staggered grids (e.g., MAC grids [M. Perić, R. Kessler and G. Scheuerer, Comput. & Fluids 16 (1988), no. 4, 389-403; Zbl 0672.76018]) is a serious impediment for the implementation of multilevel schemes in the context of finite differences. This difficulty is circumvented here by the use of a colocated finite volume discretization [S. Faure, J Laminie and R. Temam, "Colocated finite volume schemes for fluid flows'', submitted; M. Perić, R. Kessler and G. Scheuerer, op. cit.], for which the algebra of multilevel methods is much simpler than in the context of MAC type finite differences. The general ideas and the numerical simulations are presented in this article in the simplified context of a two-dimensional Burgers equation; the two- and three-dimensional Navier-Stokes equations, which introduce new difficulties related to the incompressibility condition and the time discretization, will be considered elsewhere [see S. Faure, J Laminie and R. Temam, op. cit.; "Finite volume discretization and multilevel methods for the Navier-Stokes equations'', in preparation].
ISSN: 0885-7474

hal-00730193
https://hal.archives-ouvertes.fr/hal-00730193

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
The effect of trace concentrations of Ti on the rate and mechanism of hydrogen diffusion in pure forsterite was investigated experimentally. Forsterite doped with 350–400 ppm Ti (predominantly octahedral Ti3+, minor tetrahedral Ti4+) was prepared by diffusing Ti into pure synthetic forsterite at high temperature (1500 °C), very low oxygen fugacity (~QFM-5) at atmospheric pressure. The Ti-doped forsterite was then diffusively hydroxylated in a piston-cylinder apparatus at much lower temperatures (650–1000 °C) and higher oxygen fugacities, at 1.5–2.5 GPa, with chemical activities buffered by forsterite-enstatite or forsterite-periclase and partial pressure of H2O equal to total pressure. This produced hydrogen concentration-distance profiles of several hundred micrometers in length. Diffusion of hydrogen through the Ti-doped forsterite, even at very high Embedded Image , does not lead to redox re-equilibration of the high Ti3+/ΣTi ratio set during the synthesis of the starting material at extremely reducing conditions—the metastable point defects are partially preserved.Three main hydroxylated point defects are observed; hydroxyl is associated with Ti4+ (titano-clinohumite point defects), Ti3+ (and possibly other trivalent cations), and M-site vacancies. Concentration-distance profiles represent an interplay between diffusion and reaction (i.e., site rearrangement) to form the observed point defects. In all experiments, the concentration-distance profiles of the hydroxylated Ti defects coincide with the concentration-distance profiles of the M-site vacancy substitution, with the same crystallographic anisotropy. This suggests that the macroscopic movement of hydrogen through the crystal is due to one diffusion mechanism (the diffusion of hydroxylated M-site vacancies). The net H diffusion coefficient [logD(ΣH)], between 650–1000 °C, is Embedded Image where the values of logD0(ΣH) parallel to [100] and [001] directions are −3.0 ± 0.4 and −2.2 ± 0.4, respectively; diffusion is therefore around one order of magnitude faster along the c axis than along the a axis. The diffusion of hydrogen is slightly faster in Ti-doped forsterite than in pure forsterite. There is no effect of chemical activity or oxygen fugacity on the rate of diffusion. Hydrogen diffusion profiles represent a complex interplay between the movement of H through the crystal lattice and point-defect reactions to maintain charge balance.
ISSN: 0003-004X

hal-01467402
https://hal.archives-ouvertes.fr/hal-01467402
DOI : 10.2138/am-2016-55681571

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Carbonised template silica membranes were synthesised and investigated for water desalination for brackish (0.3wt%), sea water (3.5wt%) and brine (7.5wt%) NaCl solutions at temperatures range from 22 to 60°C. The membranes were prepared by a two-step base catalysed sol-gel method using tetraethyl orthosilicate TEOS as the silica precursor and triblock copolymer of Pluronic® P123 as the templating agent. The P123 silica membranes calcined under vacuum only produced high quality membranes by the interlayer-free method. The membranes were stable during testing of up to 250h under different thermal and salt concentration solutions, always delivering very high salt rejections >99.5%. It was found that by increasing the template concentration in the silica matrix from 5 to 50wt%, salt concentration polarisation was greatly reduced. As such, high water fluxes were measured up to 8.5kgm-2h-1 for brackish water and 6.6kgm-2h-1 for brine water. © 2014 Elsevier B.V.
ISSN: 0376-7388

hal-01683210
https://hal.univ-antilles.fr/hal-01683210
DOI : 10.1016/j.memsci.2014.10.026

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Four fibers from banana-trees (leaf, trunk) and coconut-tree (husk, fabric) were examined before their incorporation in cementitious matrices, in order to prepare insulating material for construction. Their botanical compositions have been determined following a method described previously. Thermal degradation of these fibers were studied between 200 and 700 °C under nitrogen gas flow. Temperature of pyrolysis was the experimental parameter investigated. The solid residues obtained were analyzed by classical elemental analysis, Fourier Transform Infra Red (FTIR) spectroscopy and were observed by Scanning Electron Microscopy (SEM). This study has shown (1) the relation between botanical, chemical composition with both localization of fibers in the tree and type of tree; (2) the rapid and preferential decomposition of banana fibers with increasing temperature of pyrolysis and (3) the rough samples are made of hollow fibers.
ISSN: 0960-8524

hal-00809780
https://hal.univ-antilles.fr/hal-00809780
DOI : 10.1016/j.biortech.2005.11.030

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Mesoporous cobalt oxide silica matrices and membranes were successfully prepared using a dual acid-base catalysed sol-gel and interlayer-free approach for desalination applications. The effects of cobalt addition (0-35 mol%) on the structure-property relationship of the silica materials and membrane performance were systematically studied as a function of feed salt concentration (0.3-7.5 wt.% NaCl) and temperature (22-60 °C). As cobalt concentration increases beyond 5 mol%, the concentration of tricobalt tetroxide and proportion of silica mesopores were found to increase within the matrices. Silica membranes with high amount of tricobalt tetroxide (35 mol%) were found to be highly mesoporous with water fluxes of 20, 11.3 and 7.7 kg m-2 h-1 for the 0.3, 3.5 and 7.5 wt.% solutions at 60 °C, respectively, with >99.7% salt rejection at all times. This is attributed to the high pore volume (mesopores formation) and structural robustness of the silica network provided by the presence of tricobalt tetroxide. Even higher performance was achieved for low tricobalt tetroxide (mol%) silica membranes with water fluxes of 47.6 (0.3 wt.%) and 31.5 (3.5 wt.%) kg m-2 h-1 at 60 °C, respectively, though with reduced salt rejections of 90%. © 2015 Elsevier B.V.
ISSN: 0011-9164

hal-01683209
https://hal.univ-antilles.fr/hal-01683209
DOI : 10.1016/j.desal.2015.02.034

Éditeur(s) : HAL CCSD
Résumé : Ghost fishing and its consequences are little known in the French West Indies. In Guadeloupe, no allegation concerning ghost fishing was made public to date. In the absence of objective studies about this phenomenon, it is impossible to quantify the impact of these lost gears on the resource (Chaves et al. 2006). However, the characteristics of small-scale fishing existing in this area let think that it happens indeed that fishing machines are lost: - weather constraints, sometimes of catastrophic type (storms, hurricanes). The fishermen fix less racks (traps) during the period preceding the hurricane season in preparation for possible loss (Komla-Soukha and Bouchereau 2007). Of the 40 000 Caribbean traps around Guadeloupe, about 20 000 are lost each year during hurricane season, but continue to catch fish for many months (Burke and Maidens 2004); - accidents (most common causes after the literature) occurring during a fishing operation are events already well orally brought back (Macfayden et al. 2009); - the voluntary abandonment at sea of material by the fisherman for convenience reasons; - the consequences of conflicts of use (thefts, destruction of fishing gears, boardings of ships). It is the case in the Caribbean area in connection with the interactions related to the stake on resources exploitation (Blanchet et al. 2002).
Coastal Zone Asia-Pacific Conference-World Small-Scale Fisheries Congress
Bangkok, Thailand

hal-00755291
https://hal.univ-antilles.fr/hal-00755291
https://hal.univ-antilles.fr/hal-00755291/document
https://hal.univ-antilles.fr/hal-00755291/file/WSFC2010_Proceedings_Bouchereau.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : Our objective was to compare fruit morphology, physico-chemistry and bioactive compounds content ofthe edible pulp of six Mammea americana accessions. The results showed that this fruit was rather big,weighing on average 600 to 1100 g depending on the accession, and spherical to oblate-shaped. The pulprepresented between 50 and 70% of the weight of the whole fruit. The pulp adhered only partially to theseeds in 5 of the 6 accessions studied, while the last one exhibited full adherence. The fresh pulp wasacidic, sweet, succulent and crunchy. The fruits studied had a variety of qualities, providing variousopportunities for post-harvest uses: fruit salads, nectar preparation, jams and jellies, or export. We haveestablished for the first time the total phenolic compounds and total flavonoids contents in the pulp ofmamey apple fruits. The pulp colour was highly correlated with total phenolic compounds and total carotenoidscontents.
ISSN: 0308-8146

hal-01606022
https://hal.archives-ouvertes.fr/hal-01606022
DOI : 10.1016/j.foodchem.2017.04.145
PRODINRA : 395676

Éditeur(s) : Université de Montpellier II
Résumé : The sea bass, Dicentrarchus labrax, has been subjected to intensive aquaculture on the Mediterranean cost for ten years. Marine fish hatcheries are key factors in the aquaculture field, and face different pathologies, especially one of viral origin (nodavirus) that could challenge their feasibility. Consequently, we have tried to provide some data on larvae and spawning stocks. Firstly, we have studied the immunoglobulins, components of the specific humoral immunity, and their role as antibodies. On adult basses, these immunoglobulins are tetrameric molecules with high molecular weight (850 kD), made of heavy (H) - 80 kD and light (L) - 26 kD chains. In the eggs, simplest forms such as monomeric or dimeric are brought to the fore; they are located under the chorionic membrane. Secondly, we have studied the development of the immunity system on larvae, preparing IgM assays with ELISA method, the study on the organogenesis of the main lymphoid organs, and using flow cytometry for the ontogenesis of IgM producing cell. Based on this experience, we can propose a date for the immunocompetence onset of the bar, i.e. from the 54th day of the hatchery phase. Finally, we made the most of these different results to study a viral pathology (nodavirus) in spawners and larvae. We defined an experimental contamination model for larvae and eggs, and we highlighted that eggs born from vaccinated hen fishes were protected against the nodavirus.
Le bar, Dicentrarchus labrax, fait l'objet d'une aquaculture intensive sur le littoral Méditerranéen depuis une dizaine d'années. Les écloseries marines représentent un des maillons clefs de cette filière aquacole, et sont confrontées à différentes pathologies, dont une d'origine virale (nodavirus), pouvant remettre en cause leur faisabilité. Aussi, nous avons tenté d'apporter quelques données concernant la protection des larves et des géniteurs reproducteurs. Dans un premier temps, nous avons étudié les immunoglobulines, éléments de l'immunité spécifique humorale ainsi que leur rôle anticorps. Chez les bars adultes ces immunoglobulines sont des molécules tétramériques de haut poids moléculaire (850 kD), composées de chaînes lourdes (H) de 80 kD et légères (L) de 26 kD. Dans les oeufs, des formes plus simples, monomériques ou dimériques, sont mises en évidence et sont localisées sous la membrane chorionique. Dans un second temps, nous avons étudié la mise en place du système immunitaire spécifique chez les larves, en effectuant le dosage des IgM par ELISA, l'étude de l'organogenèse des principaux organes lymphoïdes, puis celle de l'ontogenèse des cellules productrices d'IgM par cytométrie de flux. L'ensemble de cette étude nous permet de proposer une date d'acquisition de l'immunocompétence à partir du 54ème jour d'élevage chez le bar. Enfin, ces différents résultats ont été mis à profit dans le cadre d'une pathologie virale (nodavirus) touchant les reproducteurs et les larves. Après avoir défini un modèle de contamination expérimental des larves et des oeufs, nous avons mis en évidence une protection des oeufs lorsque ceux-ci proviennent d'une femelle vaccinée (vaccin expérimental) contre le nodavirus.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1997/these-1265.pdf
http://archimer.ifremer.fr/doc/00000/1265/

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
This work investigates the structural formation and analyses of titania membranes (TM) prepared using different vacuum exposure times for molecular weight (MW) cut-off performance and oil/water separation. Titania membranes were synthesized via a sol-gel method and coated on macroporous alumina tubes followed by exposure to a vacuum between 30 and 1200 s and then calcined at 400 °C. X-ray diffraction and nitrogen adsorption analyses showed that the crystallite size and particle size of titania increased as a function of vacuum time. All the TM membranes were mesoporous with an average pore diameter of ~3.6 nm with an anatase crystal morphology. Water, glucose, sucrose, and polyvinylpyrrolidone with 40 and 360 kDa (PVP-40 kDa and PVP-360 kDa) were used as feed solutions for MW cut-off and hexadecane solution for oil filtration investigation. The TM membranes were not able to separate glucose and sucrose, thus indicating the membrane pore sizes are larger than the kinetic diameter of sucrose of 0.9 nm, irrespective of vacuum exposure time. They also showed only moderate rejection (20%) of the smaller PVP-40 kDa, however, all the membranes were able to obtain an excellent rejection of near 100% for the larger PVP-360 kDa molecule. Furthermore, the TM membranes were tested for the separation of oil emulsions with a high concentration of oil (3000 ppm), reaching high oil rejections of more than 90% of oil. In general, the water fluxes increased with the vacuum exposure time indicating a pore structural tailoring effect. It is therefore proposed that a mechanism of pore size tailoring was formed by an interconnected network of Ti-O-Ti nanoparticles with inter-particle voids, which increased as TiO2 nanoparticle size increased as a function of vacuum exposure time, and thus reduced the water transport resistance through the TM membranes. © 2016 by the authors.
ISSN: 1996-1944

hal-01683214
https://hal.univ-antilles.fr/hal-01683214
DOI : 10.3390/ma9110938

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
: Indoor dust samples cannot always be analyzed immediately after collection. However, little information is currently available on how storage conditions may affect measurements. This study was designed to determine how sample storage conditions may affect the concentration of semi-volatile organic compounds (SVOCs) in the dust. A composite dust was prepared using a Standard Reference Material (SRM 2585) with real indoor dust samples. The composite dust was stored in various types of packaging, at different temperatures (-18°C, 5°C, 20°C and 35°C) and in different light conditions. The concentration of SVOCs was measured after various storage durations. No effect on SVOC concentrations was observed for the composite dust stored in an amber glass vial at -18°C for 36 months. At 5°C, 20°C and 35°C, losses occurred for the more volatile compounds. The experimental storage conditions clearly showed that temperature and duration affected the concentrations of SVOCs in the composite dust. The type of packaging material (polyethylene zip bag or polyethylene garbage bag) did not seem to have a systematic effect on the preservation of SVOCs in the composite dust. Maximum storage duration times are proposed for each compound at various temperatures. For most compounds, samples can be stored for two months at 20°C. For samples that cannot be analyzed immediately, we recommend to store them in the dark at -18°C to ensure a good recovery of all tested compounds. This article is protected by copyright. All rights reserved.
ISSN: 0905-6947

inserm-00866171
http://www.hal.inserm.fr/inserm-00866171
DOI : 10.1111/ina.12066
PUBMED : 24033516

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Outbreaks of the corallivorous crown-of-thorns seastar Acanthaster planci (COTS) represent one of the greatest disturbances to coral reef ecosystems in the Indo-Pacific, affecting not only coral reefs but also the coastal communities which rely on their resources. While injection approaches are increasingly used in an attempt to control COTS densities, most of them display severe drawbacks including logistical challenges, high residual environmental impacts or low cost-effectiveness. We tested a new alternative control method based upon acidic injections of cheap, 100% natural products. We investigated the lethal doses, intra-and inter-specific disease transmission and immune responses of COTS when injected with fresh lime juice (extracted from local Citrus arantifolia) and white spirit vinegar. High COTS mortality was achieved with small volumes: 10–20 ml per seastar induced death in 89%/ 97% of injected specimens after an average 34.3 h/29.8 h for lime juice and vinegar respectively. Highest efficiency was reached for both solutions with double shots of (2 × 10 ml) in two different areas on the body: 100% mortality occurred within 12–24 h, which is similar or faster compared with other current injection methods. Multiple immune measures suggested that death was very likely caused by pH stress from the acidic solutions rather than a bacterial infection. Contagion to either conspecifics or a variety of other reef species was not observed, even at COTS densities 15 times higher than the highest naturally reported. 10 to 20 l lime juice/vinegar could kill up to a thousand COTS at a cost of less than 0.05 USD per specimen; no permits or special handling procedures are required. We conclude that injections of lime juice and vinegar offer great advantages when compared to current best practises and constitute a cheap and natural option for all reefs affected by COTS.
ISSN: 1932-6203

Droits : http://creativecommons.org/licenses/by/
hal-01208272
https://hal-univ-perp.archives-ouvertes.fr/hal-01208272
https://hal-univ-perp.archives-ouvertes.fr/hal-01208272/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01208272/file/journal.pone.0137605.pdf
DOI : 10.1371/journal.pone.0137605

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Abstract View references (35)La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) hollow fibres were prepared by a phase inversion/sintering method using polyetherimide as a binder. In order to overcome surface exchange kinetics limitation, LSCF hollow fibres were coated with ∼200nm palladium (Pd) nanoparticles. The O2 flux of best performing membranes increased by up to 350% in comparison to unmodified LSCF hollow fibres. Optimal enhancement was achieved with a single Pd coating. Additional coatings resulted in reduced O2 fluxes, thus counter acting the beneficial spill-over effect of the catalyst. Long term stability testing in atmospheric air at 850°C showed that a LSCF membrane modified with a single Pd coating continually outperformed a pure LSCF hollow fibre for over 400h, though the level of enhancement was reduced over time. A dramatic reduction in performance of more than 45% occurred within the first 24h of testing, which was attributed to the coalescence and aggregation of Pd catalyst particles to ∼1000nm size at the LSCF grain boundaries. This greatly reduced the available area for the oxygen species to spill-over onto the LSCF surface and thus reduced the overall O2 flux. © 2011 Elsevier B.V.
ISSN: 0376-7388

hal-01683196
https://hal.univ-antilles.fr/hal-01683196
DOI : 10.1016/j.memsci.2011.07.008

Éditeur(s) : HAL CCSD Elsevier
Résumé : In the context of an ongoing monitoring study on the impacts of gold-mining activities on critical ecosystem processes, we explored the use of soil Denitrifying Enzyme Activity (DEA) and Substrate Induced Respiration (SIR) as ecosystem indicators in tropical rainforests of French Guiana. We also propose DEA/SIR ratio as ecosystem attribute able to describe the state of an ecosystem and to reflect changes in ecological processes. With this purpose, we measured SIR, DEA and DEA/SIR ratio in five gold-mining areas and five surrounding natural reference rainforests. We also measured indicators in two conditions of spontaneous regeneration of vegetation (stratified or not) and two conditions of soil rehabilitation (prior preparation of soils or not). We showed a high variability of DEA, SIR and DEA/SIR ratio in the natural reference forests. This pointed out the necessity to identify relevant reference systems - i.e. proving a close match in all relevant ecological dimensions - to compare with closed perturbed systems in order to assess the levels of alterations after disturbances. Results showed a high impact of gold mine on microbial processes with a strong decrease of DEA (10-fold lower), SIR (2-fold lower) and DEA/SIR ratio (8-fold lower) in perturbed areas in comparison with natural reference forests. The type of spontaneous vegetation (stratified or not) influenced the values of indicators as well as prior rehabilitation of soils, demonstrating the capacity of DEA. SIR and DEA/SIR ratio to respond in proportion to the perturbation (robustness) and to the different levels of restoration (sensitivity). The systematic decrease of the ratio DEA/SIR observed in the studied perturbed situations demonstrates clearly that the structure of microbial communities has been also modified. The ratio DEA/SIR proved to be robust and sensitive, and able to describe in fairly fine way changes of soil microbial communities in terms of structure and function in gold mine areas and during processes of restoration. We propose to use DEA, SIR and DEA/SIR ratio as bioindicators of both structural and functional aspects of C and N cycling in soils. Together with others bioindicators based on key supporting functions in soils, these indicators should accurately evaluate the ecological potential of natural ecosystems and the levels of degradation in case of land-use changes. (C) 2012 Elsevier Ltd. All rights reserved.
ISSN: 1470-160X

hal-01190730
https://hal.archives-ouvertes.fr/hal-01190730
DOI : 10.1016/j.ecolind.2012.01.021
PRODINRA : 213639

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Depuis le passage du cyclone Hugo en 1989, la Guadeloupe est plus ou moins préparée à affronter un nouvel évènement cyclonique (alerte météo, abris anti-cycloniques, etc.). En revanche, pour ce qui concerne les tsunamis, ce n’est que depuis quelques années (après le tsunami de 2004 dans l’océan indien, le séisme de Haïti de 2010 et le tsunami du Japon de 2011) qu’une prise de conscience du risque encouru dans la Caraïbe et plus particulièrement dans l’archipel guadeloupéen s’est faite. Des projets d’évaluation de ces risques ont alors vu le jour et c’est dans le cadre de l’un d’eux (projet INTERREG IV TSUNAHOULE) que l’étude de l’aléa submersion marine pour la réserve naturelle de Petite-Terre a été réalisée. Au travers de 3 scénarios extrêmes choisis en accord avec les connaissances météorologiques et géologiques de la région, les impacts modélisés d’un tsunami, d’une houle de nord longue période et d’un cyclone de catégorie 4-5 sont présentés et discutés distinctement après avoir dressé un bilan des différents enjeux de la réserve, ce qui mène à une réflexion sur la vulnérabilité des occupants de la réserve face à ces aléas naturels.
Since the tropical hurricane Hugo devastated Guadeloupe Archipelago in 1989, the island is more or less prepared to face another cyclonic event (alerts, shelters, etc.). On the other hand, tsunamis have only become a great concern in the Caribbean and more particularly in Guadeloupe for a couple of years (after the 2004 Indian Ocean tsunami, the 2010 Haiti earthquake and the 2011 Japan tsunami). Thus research projects have been led to try to assess marine submersion hazards as the INTERREG IV TSUNAHOULE project in which this study of the natural sanctuary of Petite-Terre has been done. Through 3 extreme scenarios chosen in agreement with meteorological and geological knowledge in the region, the modeled impact of a tsunami, a long period north swell, and a 4-5 category hurricane are presented and discussed separately after having detailed the different stakes of the sanctuary, which leads to start on thought about the vulnerability of its inhabitants, temporary or not, in front of those natural hazards.
Guadeloupe
Petite-Terre

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.6643
http://journals.openedition.org/etudescaribeennes/6643

Résumé : La Norvège a toujours passé, avec quelque raison, semble-t-il, en France tout au moins, comme l'un des pays où l'industrie de la pêche est le plus développée. A diverses reprises, nous lui avons emprunté ses engins et ses méthodes. Aussi, paraît-il indispensable pour quelqu'un, dont le rôle est de faire et de diriger dans nos colonies, les études scientifiques et appliquées se rapportant à l'industrie du poisson, de visiter avec soin la Norvège, pour y étudier d'une façon aussi complète que possible, les engins, les méthodes de travail, les bateaux de pêche, la préparation des produits et aussi des sous-produits, qui intéressent d'une façon si considérable nos colonies, dont les besoins en matières azotées alimentaires et agricoles sont très grands. Nous avions pensé pouvoir accomplir notre voyage d'études en 1914 ou 1915, mais le déchaînement de la guerre mondiale, nous a, comme tant d'autres, dirigé d'un autre côté. Nous avons pu l'année dernière, reprendre notre projet, et grâce à la bienveillance de M. le Ministre des Colonies, à la générosité des grands Gouvernements généraux et de l'Office Scientifique et Technique des Pêches Maritimes, nous avons pu accomplir un voyage utile, qui, nous l'espérons, sera d'un certain profit pour la France métropolitaine, et aussi surtout, pour la France coloniale, vers laquelle nous dirigeons depuis de longues années déjà, nos constants et patients efforts.
Notes et mémoires, 1922 , Vol. 16

Droits : 1922 OSTPM
http://archimer.ifremer.fr/doc/00016/12755/9687.pdf
http://archimer.ifremer.fr/doc/00016/12755/

Éditeur(s) : HAL CCSD Taylor & Francis
Résumé : International audience
This work evaluates the influence of three different intensities of refinement of sisal pulp and the effect of accelerated aging cycles on the behavior of composites. Fiber-cements were prepared by the slurry de-watering method and pressing as a crude simulation of the Hatschek process. Mechanical behavior of composites was evaluated by four-point bending test at 28 days, and after 50 and 100 wet/dry cycles. Refinement of pulp and aging have increased the strength and bulk density of composites and decreased the toughness and porosity. The best mechanical performance after aging was achieved for samples with highly refined fibers.
ISSN: 1042-6914

hal-00809817
https://hal.univ-antilles.fr/hal-00809817
DOI : 10.1080/10426910601062065

Éditeur(s) : HAL CCSD Cold Spring Harbor Laboratory Press
Résumé : International audience
Meiotic DNA double-stranded breaks (DSBs) initiate genetic recombination in discrete areas of the genome called recombination hotspots. DSBs can be directly mapped using chromatin immunoprecipitation followed by sequencing (ChIP-seq). Nevertheless, the genome-wide mapping of recombination hotspots in mammals is still a challenge due to the low frequency of recombination, high heterogeneity of the germ cell population, and the relatively low efficiency of ChIP. To overcome these limitations we have developed a novel method--single-stranded DNA (ssDNA) sequencing (SSDS)--that specifically detects protein-bound single-stranded DNA at DSB ends. SSDS comprises a computational framework for the specific detection of ssDNA-derived reads in a sequencing library and a new library preparation procedure for the enrichment of fragments originating from ssDNA. The use of our technique reduces the nonspecific double-stranded DNA (dsDNA) background >10-fold. Our method can be extended to other systems where the identification of ssDNA or DSBs is desired.
ISSN: 1088-9051

hal-00877675
https://hal.archives-ouvertes.fr/hal-00877675
DOI : 10.1101/gr.130583.111
PUBMED : 22367190

Éditeur(s) : HAL CCSD IOP Publishing
Résumé : The Bureau International des Poids et Mesures (BIPM), Sevres, France, hosted the 7th International Comparison of Absolute Gravimeters (ICAG) and the associated Relative Gravity Campaign (RGC) from August to September 2005.;ICAG 2005 was prepared and performed as a metrological pilot study, which aimed:;(1) To determine the gravity comparison reference values;;(2) To determine the offsets of the absolute gravimeters; and;(3) As a pilot study to accumulate experience for the CIPM Key Comparisons.;This document presents a complete and extensive review of the technical protocol and data processing procedures. The 1st ICAG-RGC comparison was held at the BIPM in 1980-1981 and since then meetings have been organized every 4 years.;In this paper, we present an overview of how the meeting was organized, the conditions of BIPM gravimetric sites, technical specifications, data processing strategy and an analysis of the final results. This 7th ICAG final report supersedes all previously published reports.;Readings were obtained from participating instruments, 19 absolute gravimeters and 15 relative gravimeters. Precise levelling measurements were carried out and all measurements were performed on the BIPM micro-gravity network which was specifically designed for the comparison.
ISSN: 0026-1394

hal-00644529
https://hal.archives-ouvertes.fr/hal-00644529
DOI : 10.1088/0026-1394/48/5/003