Seroprevalence of anti-SARS-CoV-2 IgG at the first epidemic peak in French Guiana, July 2020.

Funder: National Research AgencyFunder: Regional Health Agency of French GuianaFunder: Institut Pasteur Urgence COVID-19 fundraisingBACKGROUND: While Latin America has been heavily affected by the pandemic, only a few seroprevalence studies have been conducted there during the first epidemic wave in the first half of 2020. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional survey was performed between 15 July 2020 and 23 July 2020 among individuals who visited 4 medical laboratories or 5 health centers for routine screening or clinical management, with the exception of symptomatic suggestive cases of covid-19. Samples were screened for the presence of anti-SARS-CoV-2 IgG directed against domain S1 of the SARS-CoV-2 spike protein using the anti-SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) from Euroimmun. CONCLUSIONS/SIGNIFICANCE: The overall seroprevalence was 15.4% [9.3%-24.4%] among 480 participants, ranging from 4.0% to 25.5% across the different municipalities. The seroprevalence did not differ according to gender (p = 0.19) or age (p = 0.51). Among SARS-CoV-2 positive individuals, we found that 24.6% [11.5%-45.2%] reported symptoms consistent with COVID-19. Our findings revealed high levels of infection across the territory but a low number of resulting deaths, which can be explained by French Guiana's young population structure

Orofacial reactivity to the sight and smell of food stimuli. Evidence for anticipatory liking related to food reward cues in overweight children.

International audienceWhether food liking may be a risk factor of overconsumption and overweight/obesity remains a controversial issue. So far, most studies used subjective reports to assess consummatory behavior, approaches that might overlook subtle or implicit hedonic changes to sensory properties of foods. Therefore, we used a cue-exposure approach by recording different measures of hedonic processes (orofacial reactivity, self-rated pleasantness, food preference) in 6-11 years old overweight (n=20) and normal-weight (n=20) children. Children were exposed to the smell and sight of high and low-energy density food stimuli and to non-food stimuli during pre- and post-prandial states. Their facial and verbal responses were videotaped and parent's reports of children's eating styles and appetitive traits were collected using the Children's Eating Behavior Questionnaire (CEBQ). Results showed that orofacial reactivity, as an objective measure of anticipatory liking, was more discriminative than self reports, with overweight children displaying more lip sucking than normal-weight children when exposed to high energy food pictures and to food odorants. Orofacial reactivity to food cues was also associated with BMI and children's eating styles (food responsiveness, emotional overeating, and desire to drink). Finally, overweight children classified more frequently non-food odorants as members of the food category during the pre-prandial state than during the post-prandial state, suggesting a possible influence of affective/motivational bias on odor categorization. Our findings suggest that orofacial responsiveness may be relevant to assess the sensitivity to energy-dense food reward cues in overweight children and for signaling, as an index of anticipatory liking, a potential risk for the development of overweight/obesity

Protection électrochimique appliquée en présence d'armatures de précontrainte

L'application de méthodes électrochimiques de protection contre la corrosion (protection cathodique et déchloruration) en présence d'armatures de précontrainte est susceptible de provoquer une production d'hydrogène et par conséquent un possible phénomène de fragilisation par hydrogène de l'acier. Des essais permettant de déterminer l'influence d'une surprotection électrochimique sur des câbles de précontraintes dans des solutions corrosives simulant le milieu cimentaire environnant ont été réalisés. Les paramètres étudiés au cours de ces essais sont la densité de courant imposé, la composition et la concentration de la solution corrosive. L'analyse et l'appréciation de la dégradation des armatures et notamment le phénomène de fragilisation par hydrogène sont ensuite réalisés au moyen d'essais de type mécanique, électrochimique et de dosage d'hydrogène. Cet article présentera les premiers résultats obtenus et les premières conclusions mettant en avant la fragilisation par hydrogène dans l'acier

Better understanding of tide's influence on half-cell potential and electrical resistivity measurements for reinforced concrete in marine environment

40th IABSE Symposium : Tomorrow's Megastructures, NANTES, FRANCE, 19-/09/2018 - 21/09/2018Main damage occurring on reinforced concrete (RC) structures can be attributed to the corrosion of the rebar. Chloride ions penetration and/or carbonation, as major causes of RC corrosion, are well understood for onshore structures. When dealing with structures in marine environment, more parameters must be considered, as the different exposure zones (tidal, splash and atmospheric) will have a significant influence on the corrosion behavior. This article deals with the corrosion diagnosis of the piers of the ile de Ré bridge. The objective is to provide an effective method to identify the different exposure zones based on the non-destructive measurements (half-cell potential) that are modelled taking into account the influence of the tide

Presentation of the French Project DéCoF-Ré

40th IABSE Symposium Tomorrow's Megastructures, NANTES, FRANCE, 19-/09/2018 - 21/09/2018A relevant knowledge of the state of the reinforced concrete is the basis for a successful management of the structures such as civil engineering bridges. To provide answers, IFSTTAR (coordinator), Cerema, Nantes University and Capacité SAS, SIXENSE-Concrete Company and the Département de la Charente-Maritime have contributed and funded a collaborative research project from 2015 to 2018. The French Project DéCoF-Ré meaning Decision Corrosion and Reliability of the ile de Ré Bridge has two main objectives. The first objective is to perform a reliable corrosion diagnosis of the piers of a bridge in a marine environment by means of non-destructive tests such as half-cell potential and resistivity. The second objective is to determine the durability of the concrete cover of the piers in terms of durability indicators. The aim of this paper is to present the Project DéCoF-Ré and to give some preliminary results.Savoir caractériser l'état d'une structure en béton armé est la base pour assurer la gestion des ouvrages du génie civil tels que les ponts par exemple. Avec pour ambition de répondre à cette problématique, l'Ifsttar (coordinateur, le Cerema, l4université de Nantes et sa filiale Capacités, l'entreprise Concrete et le Département de la Charente Maritime ont collaboré et financé un projet de recherche de 2015 à 2018. Le projet français DéCoF-Ré Décision Corrosion Fiabilité du diagnostic de corrosion sur le pont de l'ile de Ré a deux objectifs majeurs. Le premier est d'élaborer un diagnostic de corrosion fiabilisé sur les piles d'un ouvrage en milieu marin à l'aide de contrôles non destructifs tels que les potentiels et les résistivités. Le second objectif est de déterminer la durabilité du béton d'enrobage des piles en termes d'indicateurs de durabilité et de témoins de durée de vie. Cet article a pour vocation la présentation du projet DéCoF-Ré et de certains résultats préliminaires

Better understanding of tide's influence on half-cell potential and electrical resistivity measurements for reinforced concrete in marine environment

40th IABSE Symposium : Tomorrow's Megastructures, NANTES, FRANCE, 19-/09/2018 - 21/09/2018Main damage occurring on reinforced concrete (RC) structures can be attributed to the corrosion of the rebar. Chloride ions penetration and/or carbonation, as major causes of RC corrosion, are well understood for onshore structures. When dealing with structures in marine environment, more parameters must be considered, as the different exposure zones (tidal, splash and atmospheric) will have a significant influence on the corrosion behavior. This article deals with the corrosion diagnosis of the piers of the ile de Ré bridge. The objective is to provide an effective method to identify the different exposure zones based on the non-destructive measurements (half-cell potential) that are modelled taking into account the influence of the tide

Presentation of the French Project DéCoF-Ré

40th IABSE Symposium Tomorrow's Megastructures, NANTES, FRANCE, 19-/09/2018 - 21/09/2018A relevant knowledge of the state of the reinforced concrete is the basis for a successful management of the structures such as civil engineering bridges. To provide answers, IFSTTAR (coordinator), Cerema, Nantes University and Capacité SAS, SIXENSE-Concrete Company and the Département de la Charente-Maritime have contributed and funded a collaborative research project from 2015 to 2018. The French Project DéCoF-Ré meaning Decision Corrosion and Reliability of the ile de Ré Bridge has two main objectives. The first objective is to perform a reliable corrosion diagnosis of the piers of a bridge in a marine environment by means of non-destructive tests such as half-cell potential and resistivity. The second objective is to determine the durability of the concrete cover of the piers in terms of durability indicators. The aim of this paper is to present the Project DéCoF-Ré and to give some preliminary results.Savoir caractériser l'état d'une structure en béton armé est la base pour assurer la gestion des ouvrages du génie civil tels que les ponts par exemple. Avec pour ambition de répondre à cette problématique, l'Ifsttar (coordinateur, le Cerema, l4université de Nantes et sa filiale Capacités, l'entreprise Concrete et le Département de la Charente Maritime ont collaboré et financé un projet de recherche de 2015 à 2018. Le projet français DéCoF-Ré Décision Corrosion Fiabilité du diagnostic de corrosion sur le pont de l'ile de Ré a deux objectifs majeurs. Le premier est d'élaborer un diagnostic de corrosion fiabilisé sur les piles d'un ouvrage en milieu marin à l'aide de contrôles non destructifs tels que les potentiels et les résistivités. Le second objectif est de déterminer la durabilité du béton d'enrobage des piles en termes d'indicateurs de durabilité et de témoins de durée de vie. Cet article a pour vocation la présentation du projet DéCoF-Ré et de certains résultats préliminaires

On-site Corrosion Monitoring - Reliability

International RILEM Conference on Materials, Systems and Structures in Civil Engineering Conference segment on Electrochemistry in Civil Engineering, LYNGBY, DANEMARK, 22-/08/2016 - 24/08/2016The European countries have a great number of reinforced concrete bridges and many of them are suffering from corrosion. Prior to define a repair strategy, a precise and reliable diagnosis of the corrosion state of the reinforcing bars is mandatory. In order to carry out this inspection, many challenges remain especially for the RC structures exposed to a marine environment. The assessment strategy is based on the choice of Non Destructive Techniques taking into account their precision, location, number of measurements, the environmental conditions and duration. Currently, more empirical approaches are used by structure's owners and we propose to implement statistical methods as well as data mining for a more reliable and optimal diagnosis.Within the DéCoF-Ré project, the diagnosis tools and the evaluations made afterwards are established from data obtained on different piers of a real bridge, based on NDT such as visual inspection of the degradations, rebar's localization, half-cell potential mapping, electrical concrete resistivity mapping and corrosion rate measurements performed in 2015. The first results are presented. They concern the effect of environment on the reliability of diagnosis. An additional durability study based on the analysis of durability indicators (such as chloride profiles) will be conducted in 2016

Uncertainty assessment and decision from concrete electrical resistivity measurements on a coastal large bridge

40th IABSE Symposium : Tomorrow's Megastructures, NANTES, FRANCE, 19-/09/2018 - 21/09/2018For RC structures exposed to marine environments, chloride-induced corrosion leads to deteriorations that can be associated to different exposure conditions: tidal, splash and atmospheric. The on-site assessment of the corrosion condition of the reinforcement in concrete relies on a corrosion diagnosis which consists in different techniques and among them non destructive techniques such as half-cell potential, resistivity and corrosion measurements. Although the two first techniques are commonly used, variability and uncertainties in NDT condition assessment remain factors that need to be better understood in order to increase the reliability of the diagnosis particularly in the case of marine structures (in comparison with atmospheric structures for which literature is more important). The objectives of the Project DéCoF-Ré (2014-2017) were to study both the concrete durability and the corrosion state of the piers of the Ile de Ré bridge which is located in the French Atlantic coast. Concerning the corrosion study, visual inspections, rebar localization, half-cell potential mapping, electrical concrete resistivity mapping and corrosion rate measurements were performed during three years in order to analyse the influence of the measurement procedures, the investigated zones (pier number, side, height) and the environments (tide level, climatic conditions). This paper focuses on the resistivity measurements conducted with a four electrodes arrangement probe (Wenner type) on the piers of the Ile de Ré bridge using a vessel. Although resistivity values cannot directly provide an information on the passive/active state of the rebar because the measurement qualifies the electrical resistivity of the concrete cover (and not the resistivity of the steel/concrete interface which is usually obtained by Linear Polarisation Resistance measurements), it is a useful non destructive technique to point out the areas where the corrosion might be strongest. The purpose of this paper is to outline the errors made while measuring the resistivity given the uncertainty assessment based on both (i) the repeatability tests and (ii) the material local anisotropy and measurement's variability. Moreover, a model based on the evaluation of Probability of Wrong Assessment is proposed to help the owner of the bridge in taking a decision