ED Sciences Chimiques
Abiotic synthesis of organic molecules from simple gases and vent-related catalytic minerals under hydrothermal vent conditions.
by Grégoire BOE (Institut des Sciences Moléculaires)
The defense will take place at 13h30 - amphi 2 / Bat A9,b Bâtiment A9 - 351 Cours de la Libération 33405 TALENCE cedex
in front of the jury composed of
- Thierry TASSAING - Directeur de recherche - Institut des Sciences Moléculaires - Directeur de these
- Frédéric FOUCHER - Ingénieur de recherche - CEMHTI - Rapporteur
- Denis TESTEMALE - Chargé de recherche - Institut Néel - Rapporteur
- Vassilissa VINOGRADOFF - Chargée de recherche - PIIM - Examinateur
- Samuel MARRE - Directeur de recherche - ICMCB - Examinateur
- Sophie SOBANSKA - Directrice de recherche - ISM - Examinateur
The formation of prebiotic molecules in submarine hydrothermal vents, including both “black” and “white smoker” systems, constitutes a central hypothesis in origin-of-life scenarios. The objective of this thesis is to simulate in the laboratory, starting from simple gases and natural minerals, the physicochemical conditions observed in such hydrothermal environments. First, a quantitative co-localized infrared/Raman analytical method was developed, enabling the in situ investigation of the thermodynamics of complex fluid phases (CO₂, H₂, N₂, H₂O) under high-pressure conditions (20 MPa) as a function of temperature (40–320 °C). In addition, in order to more closely reproduce the physicochemical conditions of hydrothermal systems, the thesis aimed to design an original high-pressure “continuous flow” reactor based on flow induced by a thermal gradient, thereby mimicking the natural circulation of hydrothermal fluids. This reactor was designed to simulate both the extreme conditions (temperature between 15 and 300 °C at 20 MPa pressure) and the chemical complexity of these environments (aqueous solution in the presence of mixed gases (H₂/N₂/CO₂) and natural “catalytic” minerals such as olivine, magnetite, and pyrite). Equipped with sapphire windows, this reactor allows in situ monitoring by IR/Raman spectroscopy of the temporal evolution of the system. In parallel, batch reactor experiments were performed with gas–water mixtures in the presence of minerals, focusing primarily on the formation of oxalates as a function of pH, temperature, and gas-phase composition. Finally, a second experimental setup was developed, involving a high-pressure (15 MPa) sapphire tubular reactor for the continuous-flow mixing of a metal salt solution with an alkaline solution, thereby synthesizing tubular and porous mineral structures of variable composition under controlled pressure and temperature. The formation of these mineral structures, which could be observed directly, provides models of hydrothermal chimneys. These structures were subsequently analyzed by various techniques (SEM, µCT, XRD, Raman, IR) in order to determine the influence of the investigated parameters on their properties (composition, morphology, etc.). Taken together, these studies broaden the possibilities for reactor-based investigations under extreme conditions, provide new insights into organic synthesis processes in hydrothermal systems, and contribute more broadly to a deeper understanding of these environments.
ED Entreprise Economie Société
Crowdfunding criteria and the funding intention of entrepreneurial projects: A cross-country comparative study of Egypt and France
by Yousra AHMED ABDELMONEIM ABDELWAHED (IRGO - Institut de Recherche en Gestion des Organisations)
The defense will take place at 10h00 - Salle C 107 IAE, PUSG Université de Bordeaux 35 avenue Abadie 33000 Bordeaux
in front of the jury composed of
- JOHANNES SCHAAPER - Maître de conférences - Université de Bordeaux - Directeur de these
- Sophie NIVOIX - Professeure des universités - Université de Poitiers - Rapporteur
- Jacques JAUSSAUD - Professeur émérite - Université de Pau et des Pays de l'Adour - Rapporteur
- Bruno AMANN - Professeur des universités - Université de Toulouse - Examinateur
Crowdfunding is an increasingly important source of entrepreneurial finance, providing new opportunities beyond traditional funding channels. This doctoral thesis examines crowdfunding awareness, participation intentions, project and platform evaluation criteria, and cognitive motivational drivers in two different economic contexts—Egypt (a developing African market) and France (a developed European market) Comprising three interrelated studies, the research adopts a mixed-methods approach, combining quantitative surveys, regression analysis, and t-tests to uncover cross-national variations in crowdfunding behavior. The first study examines the potential of crowdfunding in both countries, with the objective of understanding how awareness and intention shape perceptions of crowdfunding potential. Using exploratory survey data and comparative analysis, the study shows that awareness and intention are key factors in explaining perceived crowdfunding potential, while their influence varies between the two contexts. T-tests further reveal significant differences between Egyptian and French respondents in terms of awareness, intention, and perceived potential. The second study develops a theoretical framework grounded in signaling theory and venture capital literature to identify six key signals to support crowdfunding projects: (1) project development stage, (2) reward nature, (3) positive externalities, (4) popularity, (5) market growth potential, and (6) platform quality. This research fills a critical gap by offering the first comparative analysis of funding criteria across these contexts. The third study investigates cognitive motivators through the lens of self-determination theory, demonstrating that Egyptian funders are influenced by self-worth, performance expectancy, and social norms, whereas French funders prioritize performance expectancy and self-value. These findings underscore how different cultural and economic settings shape participation psychology. Finally, the thesis develops an integrated model of crowdfunding intention, linking awareness, evaluative signals, and psychological motivations across Egypt and France. Beyond enriching theory, this thesis highlights practical implications for entrepreneurs, platforms, and policymakers in both mature and emerging ecosystems.
ED Sociétés, Politique, Santé Publique
MULTI-OMICS AS A TOOL TO EXPLORE THE LIFETIME IMPACT OF CEREBRAL SMALL VESSEL DISEASE ON DEMENTIA
by Constance BORDES (Bordeaux Population Health Research Center)
The defense will take place at 14h00 - Amphi Louis Université de Bordeaux - Campus Carreire - ISPED, 146 Rue Léo Saignat, 33000 Bordeaux
in front of the jury composed of
- Claudia SATIZABAL - Associate Professor - Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, The University of Texas Health Science Center at San Antonio - Rapporteur
- Guillaume PARé - Professor - McMaster University - Rapporteur
- Céline BELLENGUEZ - Chargée de recherche - Institut Pasteur de Lille - Examinateur
- Stéphanie BOMBOIS - Praticienne hospitalière - UMR S 1127, Department of Neurology, AP‐HP, Hôpital de la Pitié Salpêtrière - Examinateur
- Christophe TZOURIO - Professeur des universités - praticien hospitalier - Bordeaux Population Health, INSERM U1219, Université de Bordeaux - Examinateur
- Thierry COUFFINHAL - Professeur des universités - praticien hospitalier - INSERM U1034, Université de Bordeaux - Examinateur
Preserving brain health is a major challenge in the context of rapid demographic aging and the growing burden of age-related neurological diseases such as dementia and stroke. Alzheimer's disease (AD) is the leading cause of dementia, while cerebral small vessel disease (cSVD) is its main vascular contributor. Although their interactions are increasingly recognized, the pathophysiological mechanisms linking vascular and neurodegenerative processes remain poorly understood. The objective of this thesis is to explore the impact of cSVD on neurodegenerative mechanisms related to dementia, through three complementary research axes. In the first axis, we explored the phenomic profile of genetic determinants of cSVD identified in the general population. More than 50 loci were found to be associated with different MRI markers of cSVD, with nearly one-third shared across multiple markers. The genetics of cSVD highlight both the importance of genes related to extracellular matrix structure and function (EFEMP1, FBN2, VCAN) and an overlap with genes implicated in AD (APOE, MAPT, SH3PXD2A), suggesting shared biological pathways. Second, we used Mendelian randomization to examine the causal relationships between white matter hyperintensities (WMH), an MRI marker of cSVD, and AD endophenotypes, using individual-level data (UK Biobank, i-Share) and summary statistics from large international cohorts. Our findings provide evidence for a causal effect of greater WMH volume on lower cerebrospinal fluid (CSF) amyloid-β (Aβ) levels and on regional cortical thinning, particularly in the entorhinal cortex, frontal pole, and insula, with signals detectable as early as young adulthood in the entorhinal cortex. Moreover, we observed a bidirectional relationship: WMH were associated with CSF Aβ, and conversely, Aβ measured in CSF, PET, and post-mortem neuropathology was associated with WMH, with effects largely mediated by the APOE locus, the major genetic risk factor for AD. No robust associations were observed with tau protein. These results support the hypothesis of a vascular origin of neurodegenerative mechanisms and point to bidirectional interactions between amyloid proteinopathy and cSVD. Third, we investigated the role of signaling and peroxidized lipids in brain aging using metabolomic data from more than 3,000 individuals in the general population (3C-Dijon and Rotterdam cohorts). We identified 19 lipids significantly associated with greater WMH volume and smaller hippocampal volume, including a lysophospholipid (LPA(14:0) and an oxylipin (15-HETE) linked to both markers. Notably, LPA(14:0) was also associated with an increased risk of dementia and AD. A diet rich in plant-based foods and fish was associated with lower levels of deleterious lipids, suggesting an anti-inflammatory effect via the reduction of oxidative stress markers and inflammation-related metabolites. These lipids also showed genetic heritability (up to 33%) and associations with the gut microbiome, reinforcing their relevance as potential targets for intervention. Overall, this thesis highlights that vascular mechanisms contribute causally and complementarily to neurodegenerative proteinopathies, and that specific bioactive lipids are implicated in brain aging processes, modulated by genetic, nutritional, and microbial factors. These findings open perspectives for the identification of early biomarkers and the development of preventive strategies jointly targeting vascular and neurodegenerative mechanisms to slow down, or even prevent, the progression to AD and dementia.