ED Sciences Chimiques
Drying of silicone oil emulsions on absorbent substrates
by Allan SALEM (Centre de Recherche Paul Pascal)
The defense will take place at 14h00 - Amphithéatre 100 4 Allée Emile Monso, Campus INP - ENSIACET, 31400 Toulouse
in front of the jury composed of
- Véronique SCHMITT - Directrice de recherche - Université de Bordeaux - Directeur de these
- Camille DUPRAT - Directrice de recherche - Ecole polytechnique - Rapporteur
- Kevin ROGER - Chargé de recherche - Université de Toulouse, INP Toulouse - CoDirecteur de these
- Lorène CHAMPOUGNY - Chargée de recherche - Université de Toulouse, INP Toulouse - Examinateur
- Isabelle CAPRON - Directrice de recherche - INRAE - Rapporteur
- Laurence TALINI - Directrice de recherche - CNRS - Examinateur
This work aims to determine the drying and destabilization mechanisms of silicone oil emulsions deposited on paper. The system under study comprises water, silicone oil and either surfactants or polymers. The objective is to understand how a collection of droplets in contact with paper, a porous substrate capable of absorbing water and oil and whose fibers swell with water, leads to the formation of a more or less continuous silicone oil film on its surface. The study begins with the formulation of direct emulsions stabilized by surfactants or polymers, followed by coalescence testing under various conditions. Subsequently, the wetting and imbibition of the different fluids (water, surfactant solutions and oil) are measured to identify penetration pathways within the paper's porous matrix. Finally, Confocal Raman Microscopy, a powerful and versatile spectroscopic tool, is employed to probe the chemical composition both at the surface and through the thickness of the paper. This technique allows for the real-time monitoring of water content within the fibers and the composition of the fluid thin film at the air/water interface during the drying process. The final morphology of the cross-linked silicone oil film is then characterized using the same experimental setup. By probing the surface and the first ten micrometers of the paper, the amount of oil and cellulose per unit of volume is quantified, allowing for a 3D reconstruction of the film through volume rendering.
ED Sciences et environnements
Bugs beneath the sand: reconstruction of anthropic activities and paleoenvironments of the Aquitaine coastline via the archaeoentomological approach, from the Neolithic to Antiquity (L'Amélie, Soulac-sur-Mer, Gironde).
by Lisa RICHELMI (De la Préhistoire à l'Actuel : Culture, Environnement, Anthropologie)
The defense will take place at 14h00 - Amphithéâtre du bâtiment B6 Avenue des Facultés, 33600 Pessac
in front of the jury composed of
- Jean-Bernard HUCHET - Ingénieur de recherche - Université de Bordeaux - Directeur de these
- Philippe PONEL - Directeur de recherche émérite - Université Aix-Marseille - Rapporteur
- Allison BAIN - Professeure - Université Laval - Rapporteur
- Christine COUTURE-VESCHAMBRE - Professeure - Université de Bordeaux - Examinateur
- Frédérique EYNAUD - Maîtresse de conférences - Université de Bordeaux - Examinateur
- Olivier MONTREUIL - Maître de conférences - Muséum national d'Histoire naturelle - Examinateur
- Jean-Denis VIGNE - Directeur de recherche émérite - Muséum national d'Histoire naturelle - Examinateur
The site of l'Amélie (Soulac-sur-Mer) spans two kilometres of the French Atlantic coastline and faces rapid erosion and coastline retreat. Analysis of nearly 200 litres of sediment from nine archaeological structures and two environmental contexts, dated from the Middle Neolithic (4 000 BCE) to Late Antiquity (7th century CE), revealed thousands of insect remains, remarkably well preserved in anaerobic, waterlogged sediments. Owing to their close ecological specialisation and high diversity, the 250 identified insect species enabled a precise reconstruction of past palaeoenvironments and human activities. Belonging to multiple ecological and functional groups, they reveal a mosaic of habitats dominated by grasslands and pastures and characterised by the presence of numerous water sources. The earliest periods of occupation are distinguished by numerous forest species, indicating the persistence of tree cover. In contrast, later contexts yielded an open-environment fauna, reflecting deforestation that began as early as the Neolithic. For the first time in France, forest cover can be reconstructed over millennia, revealing the effects of deforestation on the local entomofauna from a diachronic perspective. The proportions of dung-associated beetles indicate a remarkably high concentration of grazing animals from the Neolithic. Until now, such an approach had only been applied in Great Britain, where comparable concentrations are attested only from the Bronze Age. Herd sizes fluctuated over time, and their distribution was constrained by both pasture availability and the salinity of water sources. The evolution of coprophagous entomofauna shows the decline, and in some cases the disappearance, of certain species, illustrating the impact of human activity and climate change on insect biodiversity. Several archaeological structures had different functions (salt production, wells, storage), as shown by their specialised insect assemblages. The processes of Neolithisation are examined in detail, including the massive expansion of pastures with the replacement of forest taxa by fauna typical of agricultural landscapes, as well as the development of long-distance exchange networks, evidenced by the presence of non-native beetles. This PhD thesis proposes a novel methodology for studying insect remains, adapted to intertidal environments. The use of statistical methods and the integration of spectrometric techniques constitute a truly innovative and interdisciplinary approach.