Portail HAL UNIV-RENNES
Not a member yet
180610 research outputs found
Sort by
Environmental Degradation Study of Polypropylene Films Incorporating Pro-Oxidants: Comprehensive Analysis and Ecotoxicological Assessment
No full textInternational audienceOur research described in this paper investigated the environmental degradation of polypropylene (PP) films incorporating pro-oxidants and assessed their impact on the ecosystem. Weathering aging effects were monitored through Fourier-Transform Infrared (FTIR) analysis, revealing significant changes in carbonyl, hydroxyl and amorphous regions post-aging. The presence of pro-oxidants intensified these changes, indicating higher oxidation levels. Contact angle measurements demonstrated decreased hydrophobicity upon aging, particularly pronounced in pro-oxidant-containing films (initial contact angle: 87.79 degrees for PP/1% Co/1% Fe, sample (F6) decreased to 79.24 degrees after aging). Differential Scanning Calorimetric (DSC) analysis revealed decreased melting temperatures (initial Tm: 159.5 degrees C for F6 decreased to 148 degrees C after aging) and the crystallinity post-aging (initial chi: 73.25% for F6 decreased to 60.17% after aging), suggesting increased susceptibility to degradation. Thermogravimetric Analysis (TGA) showed decreased thermal stability after aging, especially in PP/pro-oxidant films; the Tonset (T5); 432.00 degrees C for F6, decreased to 268.00 degrees C after aging; where Tonset is the temperature corresponding to 5% weight loss. Biodegradation tests indicated enhanced biodegradability in the pro-oxidant-containing films, with cobalt and ferrous stearate mixtures showing the highest degradation degrees (e.g., PP/1% Co/1% Fe: approximate to 77% biodegradation after 140 days). Ecotoxicological evaluations, including microbial toxicity and plant germination and growth tests, revealed no inhibitory effects of the degradation products on soil flora or plant growth, confirming their nontoxic nature. Overall, we believe this comprehensive study provides insights into the environmental fate of PP films with pro-oxidants, highlighting their potential for accelerated degradation without adverse ecological impacts
Table-ronde : "Notre relation au vivant : comment accompagner le changement ?"
No full textInternational audienceDans le cadre de travaux menés pendant ma thèse, j’ai analysé des situations d’apprentissages permises par la « pédagogie par la nature » dans des écoles de la forêt avec différentes données : d’une part des ouvrages ressources et d’autre part de terrains en France, au Royaume-Uni, en République d’Irlande et en Allemagne. J’ai fait l’hypothèse que ces structures offraient des potentialités d’apprentissages scientifiques et j’ai mené pour cela une analyse didactique. On peut ressortir les éléments suivants : -Dans ces situations d’apprentissages les enfants sont amenés à s’intéresser à des êtres vivants, à des traces d’animaux, ou à leur relation avec la nature, et aussi à mener des réalisations de transformation et de construction à partir de matériaux naturels. Les savoirs scientifiques potentiels touchent majoritairement aux habitats, aux cycles de vie des êtres vivants, ainsi qu’à l’identification des espèces. Les enfants sont amenés à observer, à écouter, à se questionner et à discuter entre eux et avec les pédagogues par la nature. -La question de l’accompagnement par l’adulte est primordiale. Les analyses montrent que les enfants sont très peu accompagnés dans la construction de savoirs scientifiques. -Au-delà d’un rapport cognitif, c’est avant tout un rapport de type affectif que la pédagogie par la nature rend possible. Notamment, ce sont des rapports de contacts sensoriels, des relations d’échanges avec les êtres vivants, ainsi que des relations de protection. Si d’autres rapports comme la domination ou le rejet peuvent exister chez les enfants, les pédagogues par la nature cherchent à les modifier. La PPN est riche de situations d’apprentissages scientifiques potentiels, mais il semble que ce ne soit pas une priorité de l’institution et que les pédagogues eux-mêmes ne soient pas toujours conscients de cette richesse
La tourbière de Kernilien Vihan à Baud : un contexte environnemental aux occupations néolithiques. in : Aurélie Crowch, David Aoustin, Yoann Chantreau, Véronique Duigou, Annette Flageul, Brigitte Flageul, Mikaël Guiavarc’h, Loïc Goude, Gwenaëlle Hamon, Patrick le Flao, Chantal Leroyer, Laure Merceron, Simon Puaud, Estelle Yven, CFRA. Projet collectif de recherche - En remontant le fleuve...Paysages et sociétés du Blavet préhistorique. Région Bretagne / Département du Morbihan (56) - DGAECAT– DC – Service archéologie, p.57-63
No full textTowards CMC measurement using an inductive RF technique for non-ionic surfactants in complex media
No full textInternational audienceDue to their unique chemical feature – associating hydrophilic and lipophilic parts in thesame molecule, surfactants are strongly used in cosmetics applications. In particular, the stability of emulsions is due to their ability to reduce surface tension. When the concentration of surfactants is enough, the barrier that they form at interfaces being saturated, they begin to aggregate in spherical micelles which are also amphiphilic structures. The associated concentration is known as Critical Micellar Concentration (CMC). On their own, i.e. with surfactants in solution, the formation of micelles can help with active product delivery control or optimization of detergency properties.In order to measure the CMC value, most methods resort to surface tension, conductivity, or fluorescence measurements. However, those techniques can lead to inaccurate evaluations due to impurities, additional compounds necessary for the stability of the product, and even surfactant nature. The CMC is particularly difficult to obtain for a complex fluid containing multiple surfactants.This work proposes an alternative technique based on inductive measurement of the complexpermittivity at RF frequencies. This quantity is directly linked to the polarizability of the electriccharges dispersed around the micelles, as explained by Gouy-Chapman’s and Stern’s models.This inductive RF technique is tested with surfactants dispersed in water, thickened water,and oil. The results are compared with ones obtained from classic methodology using tensiometer.Furthermore, the assessment of CMC value of mixture is discussed. Results demonstrate that thetechnique is sensitive enough to measure the CMC of one or multiple surfactants in various media, anticipating the interest of the technique for complex fluids usually used in cosmetic field
Bioorthogonal Chemical Engineering of rAAV Capsid: Advancing Gene Therapy Targeting Using Proteins
No full textInternational audienceWe report the chemical conjugation of a recombinant Adeno Associated Virus (rAAV) capsid with various functionalities, including proteins, using a bioorthogonal strategy. rAAVs were azido-coated or dibenzylcyclooctyne (DBCO)-coated by chemically modifying lysine or tyrosine residues. Lysine residues were modified using a phenyl isothiocyanate anchor, and tyrosine residues using either an aryl diazonium salt or a N-methyl luminol derivative. We demonstrate anchor-dependent labeling levels, as observed with biochemical assays and mass spectrometry. Strain-promoted azide-alkyne cycloaddition (SPAAC) was then implemented and evaluated on the rAAV to append functionalities such as fluorescein, biotin, and carbohydrates to the azido-coated capsids. We confirmed the efficiency of the bioorthogonal reaction and observed a stronger reactivity with dibenzylcyclooctyne (DBCO) compared to bicyclononyne (BCN). The optimized SPAAC reaction was finally used to label the viral vectors with two relevant nanobodies targeting specific immune cell receptors (CD62L and CD45). In vitro transduction assays conducted with one rAAV-nanobody conjugate demonstrated the promising targeting properties of these chemically modified vectors. Thus, we anticipate that this strategy will positively impact the field of rAAV capsid engineering and contribute in tissue-specific targeting for the optimization of gene therapy treatments
La mémoire de l'hiver 1709 en France (1709 - 2025)
No full textCe travail met en lumière toutes les formes de mémoire de l'hiver 1709, de cet événement à 2025. Il s'agit de l'hiver de référence, bien qu'il ne soit pas le plus froid. La première strate de mémoire, celle des contemporains de l'hiver 1709, est très dense et riche grâce aux multiples sources. Ces dernières témoignent de l’aspect spectaculaire de cet hiver. La domination de la mémoire de l'hiver 1709 sur les autres hivers est déjà effective. Cependant, cette mémoire a lentement disparu de la mémoire collective spontanée. L'historiographie pallie à ce manque mais implique une certaine homogénéisation, des tendances historiographiques, la polarisation des exemples venus de la Cour, ainsi que la disparition de l’explication divine donnée par les contemporains de l’hiver à cet aléa naturel. Ce discours est repris par les journalistes, les blogueurs, youtubeurs… L’hiver 1709 sert aussi de prétexte pour la mémoire divertissante : la tonalité dramatique de cet hiver sert l’invention d’histoires romanesques. La mémoire particulière de l’hiver 1709 s’explique aussi par le contexte militaire et politique de 1709 très marquant. Pour d’autres, l'hiver 1709 est le dernier hiver meurtrier. Depuis cet événement, plusieurs utilisations politiques, économiques, sociales, expliquent que l’hiver 1709 est mis en valeur. Par exemple, il est aujourd’hui une étude de cas des conséquences climatiques sur la société et l’adaptation de celle-ci à son environnement
Anticoagulant management in emergency settings: 2024 guidelines from the French Society of Emergency Medicine (SFMU), the French Society of Anaesthesia and Intensive Care Medicine (SFAR), the French Society of Thrombosis and Haemostasis (SFTH) and the French Working Group on Perioperative Haemostasis (GIHP)*
No full textInternational audienc
Co-construire la science avec la société : suivi des effets à long terme du changement global sur les estrans rocheux intertidaux avec les sciences participatives
No full textInternational audienceMarine biodiversity is facing unprecedented global changes due to the phenomenon known as “Blue Acceleration,” and addressing this issue is a critical responsibility for human societies. Intertidal areas, particularly rocky shores, are especially vulnerable, as they are located at the interface between land and sea where they experience multiple anthropogenic pressures in addition to extreme variations in natural conditions. These areas are easily accessible, very frequented and deeply rooted in local culture. As such, they present a very promising opportunity to simultaneously investigate the impact of environmental change on intertidal biodiversity and engage human societies in these questions with citizen science programs.We present here the co-construction process of developing an existing citizen science program called BioLit to study the response of gastropod communities on French rocky shores to two drivers of global change (pollution and climate change) with the ESPOIRS project. This project follows a transdisciplinary ecology-sociology approach, involving citizen scientists throughout the whole scientific process with the aim of co-constructing citizen science-based bio-indicators. We implemented this process with two contrasted groups of volunteer citizens which were involved in designing and conceptualizing indicators, formulating their needs and use for such indicators, and tailoring changes in the citizen science protocol and in the sampling schemes to ensure adequate spatio-temporal monitoring effort. These choices vary between drivers of global change, as the investigation of pollution (specifically, eutrophication) requires mainly spatial planning, whereas climate change requires temporal planning. Our work presents a model of open, inclusive and non-top-down science, following a process of joint exploration, with organized meetings bringing together a diverse range of stakeholders. These carry different types of knowledge and value systems, but also different types of normativity depending on their practice, which require reconciliation through collective arbitration. Finally, we offer a reflection on the potential of this approach, rooted in real-world contexts, to promote the sustainability of marine indicators by involving citizens at every stage and simultaneously addressing challenges from data collection to indicator use. We advocate for integrative science that builds on the close interconnection between the ocean and human societies to produce knowledge on marine biodiversity, monitor its changes and enhance ecosystem protection
Shanoir Landscape 2025
No full textThe Shanoir landscape is edited once a year by the executive committee of the Shanoir consortium. The goal of this document is to look back at the activities of the previous year and provide an overview of the Shanoir open source software, instances as well as ongoing projects and contributors