A comparison between the responses of neutral red and acridine orange: Acridine Orange should be preferential and alternative to neutral red as a dye for the monitoring of contaminants by means of biological sensors

The acridine orange (AO) and neutral red (NR) dyes, commonly used as probes to measure the internal pH in acidic vesicles, are compared in this article. The comparison between the two dyes (arising from calculations taking into account their analytical constants) illustrated that the use of AO is preferential to that of NR because the AO response is sensitive over the whole pH range between 4.0 and 7.4, whereas the NR response is effective only between pHs 4.0 and 6.0. In addition, it became evident from the mitochondrial respiration response that NR, unlike AO, is a protonophore. When taken into consideration, these two properties suggest that AO is more suitable than NR as an indicator of toxicity measurements in water samples because the environmental toxic compounds induce pH changes in the acidic vesicles of biological structures that are used as environmental biosensors

Improved bi-functional oxygen electrocatalytic performance of PteIr alloy nanoparticles embedded on MWCNT with Pt-enriched surfaces

Multi-walled carbon nanotube supported PteIr nanoparticles (PteIr/MWCNT) with different elemental ratios were synthesized by one-pot co-reduction approach under ambient conditions. The PteIr catalysts exhibit improved bi-functional activity towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and its electrocatalytic performance was clearly established using different physiochemical characterization techniques. The PteIr composition of 2:1 has a higher electrochemical surface area (ECSA) of about 85.3 m2 /g compared to other compositions (3:1 and 1:1) and Pt/MWCNT due to the effect of particle size distribution. The improved ORR/OER activity was found to be 139.4 and 740 mA/mg, respectively, for PteIr(2:1)/MWCNT with the potential difference of 760 mV for oxygen bi-functional activity. Furthermore, PteIr(2:1)/MWCNT showed much better stability for ORR compared to other compositions and Pt/MWNCT catalysts, i.e., around 76% of its initial ECSA retained with <20 mV shift in half-wave potential was obtained even after 10,000 potential cycles in acidic medium. It is believed that the Pt enriched surface, amount of Ir content, induced electronic and geometric effects play a vital role on the electrocatalytic activity enhancement of PteIr(2:1)/MWNCT as effective bi-functional oxygen electrode

Étude du comportement à court terme de produits chimiques flottants après leur déversement en mer et recherche d'un indicateur d'exposition biologique

L accroissement du trafic maritime des substances chimiques a justifié la mise en place de cette étude afin de mieux connaître le comportement en mer des produits chimiques en cas de déversements accidentels. Le naufrage du chimiquier Eiwa Maru (2002) contenant 5000 T de xylène à 20 milles au large de Tokyo, et, plus près de nos côtes, le naufrage de l levoli Sun (2000) et l accident du Bow Eagle (2002) viennent rappeler la réalité de ce besoin en soulignant l insuffisance des données disponibles et surtout des capacités à prédire rapidement et de façon fiable le comportement et le devenir de produits chimiques déversés en mer, ou encore contenus dans les cuves du navire, L objectif de cette thèse est de caractériser le comportement de produits chimiques en mer en étudiant tout particulièrement leurs cinétiques de dispersion naturelle, d émulsification et d évaporation ainsi qu en caractérisant leur aptitude à se disperser dans la colonne d eau. L ensemble de ce travail a été réalisé à trois échelles. Tout d abord détermination des principales caractéristiques physicochimiques des produits retenus au laboratoire par la mise en place d une méthodologie correspondant à nos besoins puis, études in situ (en rade abri de Brest) de leur comportement sur une période de 5 jours et enfin déterminaton de ces mêmes caractéristiques lors d une campagne en mer. Afin d étudier le plus complètement possible leur devenir dans l environnement marin, l impact du styrene sur la moule (mytilus edulis) a également fait l objet d un travail expérimental à l aide du biomarqueur d exposition NRRT.Large volumes of chemicals are produced each year. Shipment of these chemicals by boats and barge transiting along coastal marine route are numerous. Recent examples of chemical spiils as Fiwa Maru (2002) sinking with 5000 T of xylène from 20 nm of Tokyo and less far from our coastline the levoli Sun (2000) which sank and release 1000 T of styren has raised concern about the general lack of information of the fate of chemicals at sea. The goal of this study is to characterize the behaviour of some selected chemicals at sea in order to evaluate the cinetic of natural dispersion, emulsification and evaporation. This study is done in three scale in laboratory with a new methodologie created for this purpose, in a pilot scale (in Brest Harbour) and in open sea. In order to complete this physico chemical study, a biological test was also performed to evaluate the impact of chemicals on mussels (mytilus edulis), the lysosomal membrane stability is assessed by the NRRT assay.BREST-BU Droit-Sciences-Sports (290192103) / SudocPLOUZANE-Bibl.La Pérouse (290195209) / SudocSudocFranceF

Euro-Argo Final Report – January 2008 to June 2011

ARGO is an international global ocean observing system based on an array of some 3.000 autonomous floats drifting freely in the world’s oceans. Those floats, which probe the water to a depth of 2.000 m and report temperature and salinity data to land stations, constitute one of the essential components of the Global Climate Observing System. They also provide invaluable data in support of ocean and climate research, operational oceanography and ocean monitoring. The system is implemented by a large number of agencies and scientists in over 40 countries. A high level of coordination is necessary to organize efficiently the operations at sea, maintain the array, and to perform the required tasks of data management (e.g. collection, validation and quality control, distribution and availability, and safe keeping). The main objective of the EURO-ARGO consortium is to organize and consolidate the European contribution and to set up a research infrastructure in support of the global ARGO programme. Euro- ARGO having been endorsed by the ESFRI (European Strategic Forum on Research Infrastructures), the Preparatory Phase Project had several objectives to progress towards defining the appropriate legal framework, and to address several critical technical points related to instrumentation and sensors, data management, and array design. Capacity building and outreach have also been given due consideration. The most important results of the project can be summarized as follows: After extensive review of possible legal frameworks for the EURO-ARGO RI, it has been decided to adopt the ERIC status. Since this is a new concept (which was elaborated by the Commission during the course of the project) it has taken some time to obtain agreement by the project participants to join in the Consortium. The EURO- ARGO ERIC statutes have been drafted, including the governance structure, which consists of a Council, a Management Board, a Programme Office and a Scientific and Technical Advisory Group. The EURO- ARGO ERIC will include members and observers. Budgets have been proposed for the first five years, with an examination of the anticipated expenses and possible sources of national and international funding. It has been agreed that the research infrastructure will be distributed, with national activity centres and the Central research infrastructure (the ERIC) to be established in France at Ifremer. As of the end of the project, France, Germany, United Kingdom, Italy, Spain, Netherlands, Bulgaria and Greece will be members, and Ireland, Poland, Portugal will be observers. The draft statutes have been endorsed by the French ministries and forwarded to the Commission for review. The technical activities of the project considered the status of float technology and its likely evolution over the coming years (design, lifetime, cost, new sensors, improved telecommunications, etc...). A comparative evaluation has been made of new sensors like O2 and bio-geochemical sensors, ice sensing algorithms, vertical sampling strategy, transmission systems (Argos and Iridium), batteries etc. A comparison of the performances of different types of floats (Provor, Nemo and Apex) has also been made. Sampling strategies for the Nordic, Mediterranean, and Black seas have been examined. Four aspects of data processing and distribution system have been considered: enhancement of the mandatory functions related to ARGO Regional centres both in Nordic seas and in Mediterranean and Black seas; the development of new tools to help float deployment plans and monitor the behaviour at sea; definition of real-time quality control procedures for biochemical data; and improvements of the consistency of the ARGO dataset. Finally, a European ARGO user group has been set-up, outreach activities have been carried out in the Black sea; an educational web-site has been posted with pedagogical and illustrative material on ocean dynamics, observations, and the ARGO system

Synthèse et caractérisation de matériaux électrocatalytiques pour l'activation de la molécule d'eau (application dans une anode d'électrolyseur de type PEM)

Le stockage et la conversion d'énergie sont un défi scientifique majeur qui nécessite le développement de systèmes propres comme les piles à combustible. La production d'un combustible comme l'hydrogène par l'électrolyse de l'eau nécessite le développement de matériaux d'anode performants et efficaces pour diminuer les fortes surtensions observées et surtout les coûts liés à cette technologie. Ainsi des nanomatériaux d'anode à base d'oxydes de ruthénium, d'iridium et/ou d'un troisième métal non noble ont été synthétisés par deux méthodes qui sont, la méthode Pechini-Adams et la méthode polyol. Les caractérisations physico-chimiques prouvent l'existence d'oxydes métalliques et de grande surface spécifique, puis confirment la morphologie nanométrique et hétérogène des matériaux. Parmi les différentes compositions de nanomatériaux bimétalliques RuxIr1-xO2 synthétisées et étudiées, celle contenant x = 0,9 présente une bonne activité électrocatalytique pour l activation de la réaction d'oxydation de l eau. L'ajout d'un troisième métal comme le tantale, le titane, le niobium et l'étain a été bénéfique et montre que l'activité électrocatalytique peut être améliorée en diminuant la teneur en Ru et/ou en Ir. Ces nanomatériaux ont été optimisés et utilisés dans des électrolyseurs type PEM de 5 cm2 et de 25 cm2 de surface pour des tests de longue durée de plus de 1200 heures.The development of clean energy systems as fuel cells is one of the main challenges in the energy conversion and storage. The production of fuels as hydrogen by water electrolysis requires the development of efficient anode materials in order to decrease the high overpotential observed and the cost related to this technology. Anode oxide materials based on Ru, Ir and/or a third non noble metal are synthesized by Pechini-Adams and Polyol methods. The physico-chemical characterizations have confirmed the formation of oxide structure and their high specific surface area. Among the different compositions of bimetallic RuxIr1-xO2 materials studied, the sample Ru0.9Ir0.1 has presented the highest electrocatalytic activity with a long-term durability. The addition of the oxide of a third metal such as tantalum, titanium, tin and niobium has permitted to decrease the Ru and Ir contents but also to enhance the performance of the bimetallic electrocatalysts. The anode electrocatalysts synthesized to promote the water oxidation reaction were optimized and used for long-term durability tests in single 5 and 25 cm2 PEM electrolyzer cells over 1200 hours.POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Characterisation of the early events in atypical tomato root colonisation by a biocontrol agent, Pythium oligandrum.

International audienceThe specific oomycete-plant relationship established between a biological agent, Pythium oligandrum, and tomato (Lycopersicon esculentum Mill.) plants was examined over the first 48 h after inoculation of tomato roots with the antagonist. One of the most significant effects was the quick colonisation of cortical and vascular root areas by P. oligandrum (until 9 h post-inoculation); it was similar to invasions by the major pathogens of Pythium genus, and much faster than those by Pythium-minor pathogens. Despite the multiplication of hyphae in the root areas, fungal colonisation was associated with neither host wall disruption nor host cell alterations. The colonising hyphae looked healthy till the ninth hour after inoculation, then, they progressively became highly vacuolated. Cytological observations showed that, over the first 14 h of experiment, oomycete invasion was accompanied with rare host-induced defence reactions. Biochemical analysis evidenced an accumulation of phenolic compounds starting 3 h after inoculation. The 14th hour corresponded to the beginning of rishitin (phytoalexin) synthesis. Accumulation of biochemical host defence compounds was concomitant with early signs of hyphae alterations. During the next 34 h several host reactions were regularly amplified as evidenced by the plugging of invaded host cells with heterogeneous osmiophilic or high electron-dense (ED) materials. Fungal cell decay was accompanied with the formation of oogonia in the cortex, vascular parenchyma and xylem vessels. All these early events suggest a peculiar relationship established between P. oligandrum and the plant

Electrochemical activity of ruthenium and iridium based catalysts for oxygen evolution reaction

International audiencedecomposition process. The suitable heat treatment of the polymeric precursors allowed to recover metal oxides free from organic carbon, which can be oxidized to carbon dioxide during H2O splitting at elevated potentials. The materials were examined by various physicochemical techniques in order to understand their electrochemical behavior as anodes in a 5 cm(2) single proton exchange membrane water electrolyzer. Although the presence of Ir in the electrocatalyst composition contributes undoubtedly to its stability against ruthenium dissolution and the Faradaic efficiency of the PEM electrolysis cell, its great amount increases the overpotential value. The activity of the home made RuxIr1-xO2 anodes towards the oxygen evolution reaction occurs at ca. 1.5 Vat 25 degrees C