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Electrochemical atomic force microscopy (EC-AFM) experiments, including simultaneous linear polarization resistance (LPR) tests and in situ AFM imaging, under a CO2 atmosphere, were performed to investigate the adsorption characteristics and inhibition effects of a tetradecyldimethylbenzylammonium corrosion inhibitor model compound. When the inhibitor bulk concentration was at 0.5 critical micelle concentration (CMC), in situ AFM results indicated nonuniform tilted monolayer formation on the mica surface and EC-AFM results indicated partial corrosion of the UNS G10180 steel surface. At 2 CMC, a uniform tilted bilayer or perpendicular monolayer was detected on mica, and corrosion with UNS G10180 steel was uniformly retarded. Consistently, simultaneous LPR tests showed that corrosion rates decreased as the inhibitor concentration increased until it reached the surface saturation value (1 and 2 CMC). Molecular simulations have been performed to study the formation of the inhibitor layer and its molecular-level structure. Simulation results showed that at the initiation of the adsorption process, islands of adsorbed inhibitor molecules appear on the surface. These islands grow and coalesce to become a complete self-assembled layer.

International audience; ToF-SIMS and XPS are combined to study the adsorption of tetradecyl-benzyldimethyl-ammonium (BDA-C14) bromide corrosion inhibitor on carbon steel surface. BDA-C14 forms a protective layer with N-containing polar head group interacting with carbon steel surface. The adsorbed inhibitor surface coverage strongly depends on immersion time and inhibitor concentration. A maximum and uniform coverage is found for sufficiently long exposure times at a critical inhibitor concentration of about 25 ppm w. The uniform adsorbed inhibitor layer formed on the surface mitigates the formation of iron chloride/hydroxide intermediates and thus enhances the corrosion protection of carbon steel in aggressive environment.

International audience; An enzymatic biofuel cell cathode was elaborated by nano-structuration and functionalization of graphite using two consecutive plasma treatments before immobilization of laccase as a biocatalyst to perform oxygen reduction reaction (ORR) by direct electron transfer ((DET). Nano-structuration of graphite surfaces by synthesis of vertical graphen-like carbon nanowalls (CNWs) was performed by microwave excited plasma enhanced chemical vapor deposition (PECVD). Atmospheric pressure plasma jet (APPJ) system was then used to functionalize chemically the CNWs surface via a rapid and dry route. A partial fractional design evidenced two significant parameters of the APPJ treatment in terms of ORR current density: the treatment time and the inter-distance between the plasma jet and the surface of the carbon material. With the optimized APPJ treatment parameters, a four-fold enhancement of the ORR current density (-440 ± 70 µA/cm2) could be obtained on CNWs, compared to graphite electrodes. The best current density obtained was about −1 mA/cm2 with oxidized laccase covalently immobilized on the electrode without any agitation of the solution, confirming the main importance of enzyme orientation on the electrode surface for efficient DET transfer, the relevance of electrode nanostructuration and the advantage of covalent linking of the protein on the electrode surface.

Les enjeux des 26èmes journées du longitudinal (JDL) étaient d’examiner les formes de la sélection, ainsi que leurs évolutions et leurs articulations, d’interroger l’expérience de celles et de ceux qui sont sélectionnés et de celles et de ceux qui sélectionnent et de distinguer les ressemblances et les dissemblances entre les deux univers scolaire et professionnel. L’approche longitudinale requise pour ces journées a permis d’analyser les sélections successives au fil des parcours, dans le système éducatif puis vers et sur le marché du travail, ceci notamment en examinant les déterminants qui conduisent à accéder ou non à telle ou telle position dans le système éducatif (niveau, filière, spécialité, etc.) ou sur le marché du travail (qualification, secteur, etc.). À cette fin, les contributions se sont appuyées sur des méthodes quantitatives, via des enquêtes nationales ou locales, ou qualitatives, par des entretiens biographiques et/ou des interrogations répétées. Ces journées ont été organisées par le centre associé au Céreq de Toulouse du Laboratoire CERTOP (UMR-CNRS et Université Jean-Jaurès), avec la participation des laboratoires EFTS (UMR Université Jean-Jaurès et ENSFEA) et LPS-DT (EA Université Jean-Jaurès). Elles se sont déroulées en visioconférences, les 12 et 13 novembre 2020, et ont bénéficié du soutien financier de l’Université Jean-Jaurès Toulouse 2, de l’Institut national de la jeunesse et de l’éducation populaire (INJEP), du Céreq et des trois laboratoires organisateurs. Depuis plus de 20 ans, les JDL sont organisées par le Céreq ou un de ses centres régionaux associés. Elles regroupent une centaine de chercheur·e·s autour d’une thématique inscrite dans une approche longitudinale de l’analyse de la relation formation-emploi. Les actes des rencontres sont édités tous les ans par le Céreq.

Le décret du 1er octobre 2013 lance l’expérimentation de la Garantie jeunes (GJ) et charge la Direction générale de l’emploi et la formation professionnelle (DGEFP) de la piloter et les missions locales de les mettre en œuvre. Le déploiement de la GJ sur l’ensemble du territoire se déroule en plusieurs temps : Novembre 2013 : 10 territoires expérimentaux ; 2015 72 nouveaux territoires volontaires avec des entrées par vague en janvier, avril et septembre ; 2016 : 19 départements supplémentaire...

In this contribution, the influence of the adsorption of dodecylsulfate, an anionic surfactant, on the stability of colloidal aqueous dispersions containing ceria (CeO2) nanoparticles (NPs) was investigated using zetametry, UV-visible spectrophotometry, and potentiometry involving an ionic surfactant-selective electrode (ISSE). In particular, thanks to absorbance follow-ups carried out as a function of time, aqueous dispersions containing a given loading of CeO2 NPs were found simultaneously to stabilize more quickly with time and to adopt a higher opacity and a more pronounced light-yellow color as the sodium dodecylsulfate (SDS) concentration increased. Knowing that this absorbance was attributed undoubtedly to CeO2 NPs, the fact that the measured absorbance is lower for a higher amount of CeO2 NPs in suspension, as revealed by a higher opacity of the studied dispersions, is somewhat counterintuitive. Besides the higher opacity of the dispersions, a shield effect of the adsorbed SDS layer toward UV-visible light may also explain this observation. The adsorption of dodecylsulfate on CeO2 NPs was indeed demonstrated using zetametry measurements in the presence of SDS and the potentiometric method combined with an ISSE. This latter method did not only allow the accurate determination of impoverishment in freely diffusing dodecylsulfate (DS) anions resulting from DS adsorption on CeO2 NPs but it also showed that this latter obeys a Freundlich isotherm.

Background Rapid detection of the anticoagulant effect of oral factor Xa (FXa) inhibitors may be essential in several emergency clinical situations. Specific assays quantifying the drugs are performed in plasma and require a turnaround time that is too long to be useful in emergency situations. Rotational thromboelastometry (ROTEM) is a whole blood coagulation assay of blood viscoelasticity and could be of interest for FXa inhibitor detection in emergency. However, conventional ROTEM reagents only detect high amounts of inhibitors. Objective The aim of this study was first to assess the effect of whole blood components on the viscoelastic measurement of the effects of FXa inhibitors, and second to evaluate whether a modified ROTEM, triggered with a low amount of tissue factor and a saturating amount of phospholipid vesicles, can reliably detect low levels of FXa inhibitor activity in whole blood. Design Diagnostic test study. Settings A university research laboratory. From November 2014 to April 2016. Patients Sixty-six patients: 30 treated with rivaroxaban, 17 with apixaban and 19 without treatment. Intervention ROTEM was triggered with 2.5 pmol l of tissue factor and 10 μmol l of phospholipid vesicles. Main outcome measures Modified ROTEM parameters were measured in different experimental conditions: platelet-poor plasma (PPP), platelet-rich plasma, PPP supplemented with fibrinogen and reconstituted whole blood with various haematocrit levels adjusted between 30 and 60%. Modified ROTEM was further validated using whole blood from patients who were either treated or not treated with FXa inhibitors. Results Modified ROTEM allowed detection of as little as 25 ng ml FXa inhibitors in PPP, with at least a 1.4-fold increase of the clotting time (P ≤ 0.02). Neither changes of fibrinogen concentration nor variations of platelet count or haematocrit precluded FXa inhibitor detection. A lengthened modified ROTEM clotting time of more than 197 s allowed detection of FXa inhibitor concentrations above 30 ng ml in whole blood with 90% sensitivity and 85% specificity. Conclusion Modified ROTEM may be applicable in emergency situations for the detection of FXa inhibitors in whole blood.

In the petroleum industry, organic surfactant type inhibitors have been widely applied in the oil and gas industry considering their high efficiency. Carbon steels with various carbide contents have also been used extensively as pipeline materials during the transport and storage of crude oil due to their excellent mechanical properties and low cost. The previous investigation of inhibition mechanism on carbon steel is limited by lack of surface characterization techniques at a molecular level. Atomic force microscopy (AFM) can not only provide localized visual observation, but can also achieve the detection of mechanical properties of an inhibitor film. In this study, in situ AFM contact mode friction imaging and in situ AFM tapping mode phase imaging techniques have been applied to investigate the influence of the ferritic-pearlitic microstructure of carbon steel on inhibitor adsorption mechanisms during CO2 corrosion under different inhibitor concentrations. At concentration above surface saturation, AFM contact mode friction images show a large friction contrast between inhibitor covered cementite structures and ferrite structures, while in the absence of inhibitor, this friction contrast almost disappears, indicating the inhibitor adsorption induced this difference. AFM tapping mode phase images indicate uniform adsorption of inhibitor on both cementite and ferrite structures.The differences observed in these AFM analyses indicate that the adhesion force of inhibitor molecules on cementite could be smaller than on ferrite, or the molecular orientations of inhibitor molecules adsorbed on cementite and ferrite structures could be different. The special adsorption behavior of inhibitor molecules on cementite means the carbide component of the microstructure could directly influence inhibitor adsorption and may decrease inhibitor efficiency. Simultaneous linear polarization resistance tests in electrochemical AFM (EC-AFM) cell indicates a maximum inhibition efficiency at concentration above saturation. Keywords : Contact mode AFM, friction contrast, tapping mode AFM, phase contrast, cementite, ferrite, organic inhibitor, adhesion force. Statement of importance: Studies related to inhibitor adsorption mechanisms on ferritc-pearlitic carbon steels can be connected with the practical issues that iron carbide can impair the corrosion inhibitor performance on carbon steels. This AFM work connects the corrosion inhibition effect with the carbon steel components at a molecular level for the first time. Physical explanations regarding the interactions between inhibitor molecules and carbon steel microstructures can also be provided with the assistance of molecular simulations. Figure caption: Contact and tapping mode AFM images of inhibitor film formed on UNS G1018 steel at 2 CMC (100ppm) tetradecyldimethylbenzylammonium inhibitor + 1 wt% NaCl. The contact mode friction image indicates a large friction contrast between inhibitor covered cementite and ferrite structure, while the tapping mode phase image indicates a negligible softness contrast between cementite and ferrite structure. Figure 1

International audience; This study presents the use of new kind of carbon electrode materials as ultramicroelectrodes (UMEs) in the field of electrochemical DNA biosensors which has already been proven to be effective in protocols to DNA sequences hybridization. In contrast to other carbon materials such as diamond like carbon, that are difficult to integrate in microfluidic devices due to their high temperature deposition, amorphous carbon nitride (a-CNx) is easily synthesized at room temperature on various materials using sputtering techniques. Here, we report a-CNx use as microband electrodes in Glass/PDMS microfluidic devices. a-CNx electrodes were activated and then biofuntionalized by covalent grafting of a DNA probe as self-assembled monolayer (SAM) with a view to future development of a detection platform targeting circulating DNA or RNA sequences in microfluidic channels.