ED Sciences Chimiques
Rational synthesis of metal-TiO2 nanoheterodimers: application to hydrogen generation by heterogeneous liquid-phase photocatalysis
by Eugénie PARIENTE (ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux)
The defense will take place at 14h00 - Amphithéatre de l'ICMCB 87 Avenue du Dr Albert Schweitzer, 33600 Pessac
in front of the jury composed of
- Marie-Hélène DELVILLE - Directrice de recherche - Institut de Chimie de la matière consensée de Bordeaux (ICMCB) - Directeur de these
- Jean-Pierre DELVILLE - Directeur de recherche - Laboratoire Onde et matière d'Aquitaine (LOMA) - CoDirecteur de these
- Sophie CASSAIGNON - Professeure - Sorbonne université - Institut de Science des Matériaux (iMAT) - Rapporteur
- Peter HESEMANN - Directeur de recherche - Université de Montpellier - Institut Charles Gerhardt Montpellier (ICGM) - Rapporteur
- Stéphane PAROLA - Professeur - Ecole Normale Suppérieure de Lyon (ENS) - Examinateur
- Laurence CROGUENNEC - Directrice de recherche - Institut de Chimie de la matière consensée de Bordeaux (ICMCB) - Examinateur
Colloidal metal-semiconductor (M-SC) nanocrystals represent a significant breakthrough in the field of photocatalysis, offering promising performance for converting solar energy into fuel. Their efficiency relies on two key aspects: optimal separation of photoexcited electrons and holes, and enhanced light harvesting. Among SCs, metal oxides such as TiO2 are chemically stable but face a limitation due to their wide band gap, which restricts their photocatalytic efficiency to only 4-5% of the solar spectrum, within the UV range. To overcome this issue, this work proposes combining a metal with TiO2 using laser photodeposition to produce M-TiO2 heterodimers. Unlike conventional techniques that involve a UV lamp, this approach uses a focused laser beam to photoactivate redox reactions at the surface of TiO2 nanoparticles (NPs), allowing precise control over the size and localization of the metals. The reaction medium consists of TiO2 NPs (either bipyramidal anatase with controlled {101} and {001} facets, or non-faceted ellipsoids) dispersed in a hydro-alcoholic mixture containing metal salts. The goal is then to use these dimers for hydrogen (H2) production and to compare their photochemical efficiency. Two types of TiO2 NPs were therefore synthesized and characterized: bipyramids, which enable regioselectivity of redox reactions through their {101} and {001} facets, and ellipsoids, used as a reference for comparative study. The photodeposited metals (gold (Au), platinum (Pt), and palladium (Pd)) form metallic nanodots (NDs) on both types of NPs. Their characterization relies on electron microscopy (TEM/HRTEM) to analyze ND size, morphology, and distribution, as well as UV-vis spectroscopy for optical properties. In the case of gold, the size and growth of a single nanodot per TiO2 nanoparticle are controlled by adjusting the illumination time and the ratios of precursors. Their localization occurs preferentially on the {101} facet of bipyramids, and precise prediction of their final size is achieved via a mass conservation criterion. For palladium, the number of nanodots can be controlled while maintaining their localization on the {101} facet, by adjusting the amount of sacrificial agent (methanol). For platinum, the distribution of nanodots varies depending on the presence or absence of MeOH, shifting from a uniform distribution (without MeOH) to preferential localization on a specific facet (with MeOH), though with no precise control over the number of nanodots. The performance of Au-TiO2, Pd-TiO2, and Pt-TiO2 systems in H2 production tests in the presence of methanol yielded the following results. For gold, where only a single nanodot is observed, deposition on bipyramids results in higher activity than on ellipsoids, attributed to the presence of TiO2 facets. For palladium, multiple nanodots allow investigation of the influence of nanodot number on H2 production for the same deposited metal mass. Platinum appears to be the most efficient co-catalyst. Finally, a new model was developed to better understand the mechanisms involved in H2 production reactions under conditions where either a single metallic nanodot or multiple nanodots are present. This model was also successfully compared with data from the literature, thereby reinforcing the obtained conclusions.
ED Droit
The Scope of Application of the EU Regulation of 20 May 2015 on Insolvency Proceedings
by Candice MICHEL (INSTITUT DE RECHERCHE EN DROIT DES AFFAIRES ET DU PATRIMOINE)
The defense will take place at 14h00 - Salle des thèses Avenue Léon Duguit Bâtiment C 33600 PESSAC
in front of the jury composed of
- Laura SAUTONIE-LAGUIONIE - Professeure des universités - Université de Bordeaux - Directeur de these
- David ROBINE - Professeur des universités - Université de Bordeaux - Examinateur
- Rémi DALMAU - Professeur des universités - Université de Lorraine - Rapporteur
- Cécile LISANTI - Professeure des universités - Université de Montpellier - Rapporteur
- Adrien TEHRANI - Professeur des universités - Université de Montpellier - Examinateur
Over the years, the number of insolvency proceedings with a cross-border dimension has increased significantly. Dealing with these specific proceedings proves to be more complex. While they pose the same risks as national proceedings – such as risks to employment and the economy, the liability of business leaders and market fragility – their international nature also leads to additional difficulties. These proceedings will produce effects in different countries that do not share the same approach to insolvency law. Dealing with them therefore requires coordination between different domestic legislations that may be concurrently applicable but also between numerous jurisdictions and practitioners. To ease the management of these European insolvency proceedings, the EU legislator adopted the Regulation 2015/848 on 20 May 2015. In force since 26 June 2017, the Insolvency Regulation approximates and coordinates domestic legislations by establishing uniform rules on conflicts of laws, the mutual recognition of judgements, and their enforcement. However, for these provisions to be useful, the Regulation must be applied effectively. This raises the fundamental yet practical question of its scope of application. National courts will be the first to address this issue, since the Regulation sets an obligation for them to assess their judicial competence according to its rules. Aside from this practical aspect, the scope of application of the Regulation is fundamental to both its efficiency and legitimacy. The former because its adequate application is crucial to ensure that the text meets its purpose. The latter because its application automatically excludes any other rule of international private law. Despite the various improvements it brings, particularly compared with the former Regulation 1326/2000 of 29 May 2000, several doubts still linger over the exact definition of the material and territorial scopes of the Regulation 2015/848. While its article 1, supposed address this issue, it fails to mark out the exact boundaries of its application. Defining them with precision thus required a thorough analysis of the Regulation as a whole, particularly certain key concepts such as cross-border effects, COMI, insolvency proceeding or even related actions, as well as a careful examination of the rulings of the ECJ, whose interpretation remains fundamental to clear understanding of this European legislation.
The legal framework for the economic intermediation activities of digital platforms in Côte d'Ivoire : study in light of french law
by Koffi YAPO (CENTRE EUROPÉEN DE RECHERCHES EN DROIT DES FAMILLES, DES ASSURANCES, DES PERSONNES ET DE LA SANTÉ)
The defense will take place at 14h00 - Salle 1 K Pôle juridique et judiciaire de l'université de Bordeaux 35 place pey berland 33000 bordeaux
in front of the jury composed of
- Laurent BLOCH - Professeur des universités - Université de Bordeaux - Directeur de these
- Bernard ADOUKO - Maitre de conférence agrégé - Université Alassane Ouattara - CoDirecteur de these
- Sophie HOCQUET-BERG - Professeure des universités - Université de Lorraine - Rapporteur
- Laura VITALE - Professeure des universités - Université de Lille - Rapporteur
- Aboudramane OUATTARA - Professeur Titulaire - Université Félix Houphouët-Boigny - Examinateur
With the recent establishment of platforms such as Yango and Jumia in Côte d'Ivoire, the local economy is confronted with new models of economic exchange organization, based on algorithmic intermediation and driven by digital platforms. These platforms connect multiple actors, called users, according to an economic model that is difficult to fit within the current Ivorian legal categories. Although presented as simple interfaces, they often decisively influence the contractual relationships between users. Moreover, they operate on a two-sided market that they create and for which they determine the economic, legal, and technical conditions of operation. The success of this market relies on the network externalities it generates and on the massive use of data and sophisticated algorithms, often opaque to users. Thus, because it deviates from the traditional economic models on which current Ivorian law is built, the economic intermediation activity of digital platforms raises numerous legal challenges, notably in determining the status of the actors and providing appropriate protection for users. Faced with platforms operated by economically powerful companies, users find themselves in a structurally unbalanced contractual relationship, exacerbated in Côte d'Ivoire by high illiteracy and poverty rates. This model also favors anti-competitive practices and complicates the state's ability to collect taxes. While these issues are universal, responses must take into account local socio-economic and legal realities. In Côte d'Ivoire, the legal framework remains fragmented, incomplete, and lacking an overall vision, allowing platforms to exploit loopholes and hindering the development of local initiatives. It is therefore necessary to propose a coherent framework adapted to this particular type of intermediation, ensuring user protection, market fairness, and contestability, while fostering the growth of the digital economy. To achieve this, it is essential to analyze the functioning of these platforms in depth in order to identify and precisely define the roles of all actors involved in this intermediation activity. Regarding platforms, two main categories will be distinguished: those falling within existing legal categories and those that do not, for which a specific status will be proposed. For users, the analysis will show their insufficient protection, due either to difficulties in classification or to the inadequacy of Ivorian law. Proposals will be made to address these gaps. A liability regime adapted to the functioning of platforms will also be proposed, taking into account their actual degree of involvement in user relationships. Ex ante accountability mechanisms, notably through compliance, will also be considered, after highlighting the shortcomings of current regimes in ensuring fair redress for damages. Finally, comparative law, mainly French and European, will enrich the analysis, allowing existing frameworks to be adapted to Ivorian realities without mechanical transposition. As the first study of this scale in Francophone Africa, this thesis aims to provide proposals that can be transposed to other similar African contexts.
ED Sciences et environnements
Grapevine susceptibility to esca: exploring the underlying mechanisms in a range of cultivars through a physiopathology-based approach.
by Pierre GASTOU (SAVE - Santé et Agroécologie du VignoblE)
The defense will take place at 9h30 - Amphithéâtre de l'ISVV Institut des Sciences de la Vigne et Vin 210 Chemin de Leysotte CS50008 - 33882 Villenave d'Ornon
in front of the jury composed of
- Chloé DELMAS - Directrice de recherche - INRAE - UMR SAVE - Directeur de these
- Hervé COCHARD - Directeur de recherche - INRAE - UMR PIAF - Rapporteur
- Katia GINDRO - Directrice de recherche - Agroscope - Groupe Mycologie - Rapporteur
- Eric GOMES - Professeur des universités - Université de Bordeaux - UMR EGFV - Examinateur
- Mireia GOMEZ-GALLEGO - Ingénieure de recherche - INRAE - UMR IAM - Examinateur
- Christophe MOUGEL - Directeur de recherche - INRAE - UMR IGEPP - Examinateur
Harnessing the high intraspecific diversity of woody plants in planting and breeding programs is a promising lever for sustainably managing their health. The biotic component of woody plant decline (in both wild and cultivated species) has been less studied than its abiotic counterpart. However, clear differences in susceptibility to such stresses exist among genotypes, probably linked to their physiological diversity and their interactions with microorganisms. In this work, we used esca, a complex vascular disease of major economic concern due to its role in grapevine decline and the scarcity and difficulty of implementing effective management strategies, as a model system. The objectives of this thesis, in which we used an integrated physiopathological approach, were: (i) to describe the susceptibility of 46 grapevine cultivars (Vitis vinifera L. ssp. vinifera) to esca and dieback; (ii) to identify varietal traits associated with esca susceptibility, and (iii) to compare the response to esca of cultivars with contrasting susceptibilities. First, between 2017 and 2023, we monitored the incidence and severity of esca and declining phenotypes (apoplexy, mortality) in these 46 cultivars grown in a common garden vineyard. We identified a broad varietal gradient in the incidence of esca foliar symptoms, consistent over time and correlated with the gradient observed at the national scale in France. Cultivars with low vigour and high water-use efficiency appeared to be weakly susceptible. We then compared hydraulic and anatomical properties, as well as physiological responses to esca, in a subset of cultivars. The least susceptible genotypes displayed the lowest stomatal and minimum leaf conductances. We identified a syndrome of responses to esca (vascular occlusions, reduced carbon assimilation and storage), common to all cultivars regardless of their susceptibility. We demonstrated that the accumulation of certain secondary metabolites (terpenes and phenylpropanoids, including glycosylated compounds) in esca-symptomatic stems was more pronounced in the most susceptible cultivars. At the trunk level, we investigated the influence of wood–microorganism interactions on esca expression. Among the types of necroses identified, only the abundance of white-rot necrotic wood was correlated with esca expression. Its abundance in esca-symptomatic plants was higher for the most susceptible cultivars. Microbial communities of healthy wood did not vary significantly along the gradient of susceptibility. However, the wood of susceptible cultivars was depleted in extractives and marginally enriched in hemicellulose. It also accumulated certain phenylpropanoids in response to esca, although to a lesser extent than stems. Overall, these results show that cultivars whose physiology favors wood degradability (through its composition), deregulated production of specific secondary metabolites, and their transport from trunk to leaves - via the sap flow - appear to be constitutively more susceptible to white-rot and foliar symptoms. The biological origin of these metabolites and their spatio-temporal dynamics within the plant remain to be explored to better understand the link between wood degradation and esca foliar symptom expression. More broadly, this thesis demonstrates the major role of physiological functioning in shaping intraspecific diversity of woody plant susceptibility to complex diseases. It paves the way for further integrative studies aiming to identify genotypes resilient to stresses and adapted to global change.
ED Sociétés, Politique, Santé Publique
Epidemiology of chronic respiratory diseases and environmental factors
by Nolwenn JESTIN-GUYON (Bordeaux Population Health Research Center)
The defense will take place at 14h00 - Amphithéâtre Louis PA Institut de Santé Publique d'Epidémiologie et de Développement (ISPED) Université de Bordeaux, Campus Carreire 146 Rue Léo Saignat 33000 Bordeaux France
in front of the jury composed of
- Chantal RAHERISON-SEMJEN - Professeure des universités - praticienne hospitalière - Université de Bordeaux - Directeur de these
- Nicolas ROCHE - Professeur des universités - praticien hospitalier - Université Paris Cité - Rapporteur
- Gaëtan DESLéE - Professeur des universités - praticien hospitalier - Université de Reims - Rapporteur
- Claire ANDREJAK - Professeure des universités - praticienne hospitalière - Université de Picardie Jules Verne - Examinateur
- Mathieu MOLIMARD - Professeur des universités - praticien hospitalier - Université de Bordeaux - Examinateur
- Isabelle BALDI - Professeure des universités - praticienne hospitalière - Université de Bordeaux - Examinateur
Symptoms of chronic obstructive pulmonary disease (COPD) and asthma appear at an early age. They result from multiple environmental exposures throughout life (air pollution, occupational exposures, etc.) in interaction with genetics factors. Considering the current and future worldwide burden of these diseases (especially among women), whose effects may be worsened due to climate change, the aim of this thesis work was to identify the importance of environmental factors in COPD and asthma, by proposing a global approach of their understanding. The 1st chapter aimed to investigate the relation between chronic exposure to biomass fuel and respiratory symptoms among 661 children (<15 years old) included in the madabiomasse cross-sectional study (2016>