ED Sciences Physiques et de l'Ingénieur
Structural and optical properties of networked molecular emitters encapsulated in BNNTS, placed in mixed-dimensional heterostructures with 2D semiconductors
by Juliette LE BALLE (Laboratoire Photonique, Numérique & Nanosciences)
The defense will take place at h00 - Amphithéâtre 1 rue François Mitterrand 33400 Talence
in front of the jury composed of
- Etienne GAUFRES - Chargé de recherche - Université de Bordeaux - Directeur de these
- Sofie CAMBRE - Associate Professor - University of Antwerp - Rapporteur
- Hanako OKUNO - Directrice de recherche - Université de Grenoble Alpes, CEA, IRIG-MEM, Grenoble, France - Rapporteur
- Stephane CAMPIDELLI - Directeur de recherche - CEA-IRAMIS - Examinateur
- Yuichiro KATO - Associate Professor - Riken Nanoscale Quantum Photonics Laboratory - Examinateur
- Annick LOISEAU - Directrice de recherche - ONERA LEM - CoDirecteur de these
This thesis falls within the field of nanomaterials applied to optoelectronics. It involves the fabrication and study of optically active 0D-1D-2D mixed-dimensional heterostructures that are stable in their environment. These heterostructures will be presented as the assembly of two major components: emitting molecules (e.g. sexithiophene) or non-emitting molecules (e.g. anthracene) encapsulated inside boron nitride nanotubes (Mol@BNNT). The latter protect the molecules from the environment while allowing their optical properties to be studied since BNNTs are transparent in the visible spectrum. The second component will be flakes of exfoliated 2D TMDC materials. This thesis will be presented in three parts. First, the study of the effect of homogeneous (a single type of molecule) and heterogeneous (two types of molecules) encapsulation on the properties of the encapsulated molecules, such as their emission and radiative lifetime. In a second step, an in-depth S/TEM study involving imaging (STEM-DPC) and chemical analysis (STEM-EELS) will be conducted on the Mol@BNNTs to visualize their molecular organization as a function of BNNT diameter and encapsulation type (homogeneous VS heterogeneous). Finally, various mixed dimensional heterostructures will be fabricated and studied based on the deposition of Mol@BNNTs on the surface of WSe2 or MoS2 exfoliated flakes. The deposited Mol@BNNTs will present homogeneous properties (100% sexithiophene) or heterogeneous properties with the use of Mol@BNNTs resulting of different 6T:Anthracene encapsulation ratios. The optical properties of these heterostructures will be studied using photoluminescence, Raman spectroscopy and fluorescence lifetime analysis.
ED Sociétés, Politique, Santé Publique
Effects of transcutaneous vagus nerve stimulation on emotional control and executive functioning in Prader–Willi syndrome: STIM-PRADER
by Camille NAHON (Laboratoire de Psychologie)
The defense will take place at 9h00 - Amphithéâtre Pîtres Amphithéâtre Pîtres Faculté de Psychologie - Université de Bordeaux 3 TER place de la Victoire 33 000 BORDEAUX
in front of the jury composed of
- Virginie POSTAL - Professeure des universités - Université de Bordeaux - Directeur de these
- Emilie MONTASTIER - Professeure des universités - praticienne hospitalière - Université de Toulouse - Faculté de Santé - CoDirecteur de these
- Bruno QUINTARD - Professeur des universités - Université de Bordeaux - Examinateur
- Michèle GUIDETTI - Professeure émérite - Université de Toulouse Jean Jaurès - Rapporteur
- Philippe ALLAIN - Professeur des universités - Université d'Angers - Rapporteur
- Maïthé TAUBER - Professeure émérite - Université de Toulouse - Examinateur
Prader–Willi syndrome (PWS) is a rare genetic disorder characterized by a wide range of emotional, behavioural, cognitive, and metabolic disturbances that substantially affect individuals and their families. To date, no comprehensive therapeutic approach has been developed to address the full range of difficulties associated with PWS. Although first described in 1956, recent studies have suggested the presence of dysautonomia, associated with dysregulation of the autonomic nervous system, which plays a key role in maintaining the body's physiological homeostasis (Butler et al., 2023). The vagus nerve plays a central role in this regulation by connecting the central and peripheral nervous systems and innervating the majority of the body's organs (Brodal, 2010). The Neurovisceral Integration Model describes the involvement of the vagus nerve in emotional, behavioural, cognitive, and physiological regulation through a large network of reciprocally interconnected brain regions and neurons known as the central autonomic network (Smith et al., 2017; Thayer & Lane, 2009). Only two pilot studies (Manning et al., 2016, 2019) have investigated auricular transcutaneous vagus nerve stimulation (aVNT) to evaluate its effects on difficulties associated with PWS. Promising results have been reported, particularly regarding the temper outbursts characteristic of the syndrome. Given the relationship between behavioural disturbances and emotional difficulties in PWS (Nahon et al., submitted) and the modulatory potential of aVNT reported in the literature, this thesis aims to evaluate the safety, feasibility, and efficacy of daily 4-hour aVNT sessions administered over a 9-month period. A multicentre, single-blind, randomized controlled trial was conducted involving 24 adults with PWS and 24 of their caregivers (Nahon et al., under revision). This longitudinal study was the first to include a sham stimulation control condition. Group-level and individual-level analyses were performed using repeated measures of emotional control, together with neuropsychological assessments, computerized cognitive tasks, and questionnaires administered every three months. The study evaluated the effects of aVNT on emotional regulation, executive dysfunction, hyperphagia, depressive symptoms, and quality of life. No serious adverse events were observed, while protocol feasibility was moderate (difficulties maintaining electrode placement and the long daily stimulation duration), resulting in a high attrition rate (67%), with only eight participants completing the entire protocol. Although these limitations warrant cautious interpretation, the analyses revealed a significant improvement in emotional control during the post-treatment phase (Month 9) exclusively in the active stimulation group. These findings support the hypothesis of a gradual beneficial effect of aVNT on emotional regulation. A reduction in the functional impact of executive dysfunction, reported only by caregivers, was also observed in the active stimulation group, with improvements emerging as early as Month 3. In contrast, no significant improvements were found in executive functions assessed through computerized cognitive tasks (response inhibition, cognitive flexibility, working memory updating, and planning), depressive symptoms, hyperphagia, or quality of life. Nevertheless, trend-level effects and large effect sizes observed for the latter three outcomes may reflect insufficient statistical power related to the high attrition rate. Overall, this thesis provides encouraging evidence in support of aVNT in individuals with PWS. It also discusses the methodological limitations of the present study and the adaptations required to guide future research.