Résultats de recherche

Conférence de Chimie donnée par le Dr. Thomas Boltje de l'Université de Radboud de Nimègue.Bienvenue à tous.

Jury Prof. Gaëlle PONTAROTTI (Université de Namur), présidenteProf. Claire DIEDERICH (Université de Namur), secrétaireProf. Christel MOONS (Université de Gand)Prof. Karin HANNES (KULeuven)Prof. Franck MEIJBOOM (Universiteit Utrecht)Prof. Saskia ARNDT (Universiteir Utrecht)Dr Claudia HIRTENFELDER (Independent Researcher)Dr Trudy SHARP (Department of Regional NSW, Australia) Résumé Le rapport 2018 des Nations Unies World Urbanization Prospects prévoit que d’ici 2050, 68 % de la population humaine vivra en zone urbaine, ce qui causera une augmentation des interactions entre les humains et les animaux non humains. Jusqu’à présent, la recherche sur le bien-être des animaux s’est principalement concentrée sur les environnements contrôlés tels que les laboratoires, la production animale industrielle et les zoos. Cependant, dans les milieux urbains, la complexité des écosystèmes et les effets des interactions homme-animal doivent être pris en compte. L’argumentation de cette thèse est que la science du bien-être animal devrait être élargie pour inclure et répondre aux défis spécifiques des contextes urbains. En effet, la biopolitique urbaine actuelle privilégie principalement les intérêts humains et ignore souvent les perspectives et les besoins des animaux domestiques et commensaux.La thèse présente cinq publications, qui examinent le développement, la mise en oeuvre et la perception publique de la gestion gouvernementale qui influence le bien-être des animaux urbains. Deux questions de recherche sont élaborées sur la base des lacunes identifiées afin d’étudier les aspects éthiques, scientifiques et politiques du bien-être des animaux urbains en Belgique. D’une part, comment la politique gouvernementale et sa mise en oeuvre influencent-elles le bien-être des animaux urbain (domestiques et commensaux), avec une attention particulière pour les chats, chiens, pigeons, renards, souris et rats ? D’autre part, quelles stratégies peuvent améliorer la coexistence harmonieuse urbaine de ces animaux avec les humains du point de vue du bien-être animal ? Les réponses à ces questions seront fournies lors de la défense publique. Abstract The 2018 UN World Urbanization Prospects report predicts that by 2050, 68% of the human population will live in urban areas, which will lead to an increase in interactions between humans and non-human animals. Animal welfare research has hitherto mainly focused on controlled environments such as laboratories, animal industry and zoos. In urban environments, on the other hand, the complexity of ecosystems and the effects of human-animal interactions must be taken into account. The thesis in this dissertation is that animal welfare science should be further developed to tackle the specific challenges of urban contexts. In addition, current urban biopolitics gives priority to human interests and often ignores the perspectives and welfare needs of both domestic and commensal animals.The dissertation presents five publications, looking at the development, implementation and public perception of governmental policy and management that influences the welfare of urban animals. Two research questions are developed based on the identified research gaps in order to study the ethical, scientific and policy-related aspects of urban animal welfare in Belgium. On the one hand, how do governmental policy and its implementation influence the welfare of urban animals (domestic and commensal), with particular attention to cats, dogs, pigeons, foxes, mice and rats? On the other hand, what strategies can enhance the harmonious urban coexistence of these animals and humans from the point of view of animal welfare? Answers to these questions will be provided during the public defense.

JuryProf. DE BOLLE Xavier (UNamur), PresidentProf. VINCENT Stéphane (UNamur), SecretaryProf. BOLTJE Thomas (Radboud University)Prof. GUIANVARC’H Dominique (Paris-Saclay University)Prof. WOUTERS Johan (UNamur)AbstractMannose is a carbohydrate that we can naturally find in some bacterial cell envelope, more precisely in lipopolysaccharide core. To explore the metabolic route of this natural sugar: Metabolic Gylcoengineering (MGE) has been employed for studying biomolecules in living systems. We aim to chemically modify the cell surfaces to install unnatural monosaccharides that are metabolically transformed and incorporated by microorganisms. The metabolic incorporation into glycans pathway can be visualized by biorthogonal click reactions with fluorescent reporters that can bind to unnatural carbohydrates. In this project, the strategy is to synthesize several mannose derivatives to target the metabolic route of D-mannose and explore the glycosylation pathway in Gram-negative bacteria.On top of that, another application is to apply this clickable mannose as an interesting building block to synthesize nucleotide sugar for antibodies (Ab) functionalization. Indeed, antibody-drug conjugates (ADC) constitute a new emerging class of highly potent pharmaceutical drugs, especially in cancer therapy. The aim is to perform regioselective modification in antibody’s subunit containing glycan chains from GDP-mannose derivative. This latter must be synthesized and tested as unnatural mannose donors for glycosyltransferase that catalyzes the transfer of sugar moiety to mannose acceptor in specific site of the antibody. 

Au programme 13h30 | Exposés des lauréats13h30 | Luca Dorio (UMons)14h05 | Guillaume Gégo (UMons)14h40 | Manon Lenoir (UCLouvain)15h15 | Madeleine Martinussen (UCLouvain)16h00 | Camille Ponsard (UNamur)16h35 | Baptiste Vincent (UCLouvain)17h10 | Délibération du jury18h00 | Attribution des deux prix suivie d'une réception à l'espace Bauchau

Cet événement est ouvert à tous, jeunes et seniors, partenaires académiques et industriels, avec une priorité aux doctorants pour les conférences. Nous souhaitons encourager les directeurs de thèse à faire de cet événement un succès en invitant tous leurs étudiants à y participer. La langue de la réunion sera l'anglais.   Trois orateurs principaux sont prévus :Vincent Rodriguez (Université de Bordeaux, France) | Utilisation de la lumière polarisée linéairement pour sonder l'activité chiroptique non linéaire des molécules et des foldamères d'oligoamides aromatiquesProf. Tatjana N. Parac-Vogt (KU Leuven) | Enzymes artificielles basées sur des grappes d'oxydes métalliques : des espèces discrètes aux matériaux étendusChristophe Copéret (ETH Zürich, Suisse) | Contenu préliminaire « Moitié catalyse et moitié RMN ». Différents créneaux pour 10 short talks (15 mins de présentation + 5 mins de Q/A) ainsi que 10 flashs posters (2 mins) seront disponibles pour les doctorants. Les doctorants et les chercheurs post-doctorants auront également la possibilité de présenter leurs travaux lors de sessions de posters. Les meilleures présentations orales et affichées seront récompensées.La participation est gratuite mais l'inscription est obligatoire via ce formulaire... 

JuryProf. Yoann OLIVIER (UNamur), PresidentProf. Luc HENRARD (UNamur), SecretaryProf. Ken HAENEN (UHasselt)Prof. Danny VANPOUCKE (UHasselt)Prof. Paulius POBEDINSKAS (UHasselt)Prof. Rozita ROUZBAHANI (UHasselt)Prof. Audrey VALENTIN (Université Sorbonne Paris-Nord)Prof. Anke KRÜGER (Universität Stuttgart)Dr Michael SLUYDTS (ePotentia)RésuméRadical attack and recombination are thought to play an important role in the atomic-scale mechanisms driving the growth of diamond. Unfortunately, accurate ab-initio calculations of the growth mechanisms are scarce. This work presents an analysis of growth-related reactions, including the ones involving hydrogen and methyl radicals, on (100), (111) and (113) H-passivated diamond surface. The reactions investigated here include the migrations of different species. The reactions between the intermediate growth steps of the nucleation (including some etching mechanisms) are characterised through their reaction rate coefficients.The (climbing) nudged elastic band method is used to identify the minimum energy path of the reactions, which reveals either a tight or a loose transition state depending on the presence or absence of an energy barrier.  Following the determination of the energy profile a given reaction, the vibrational spectra of its reactants, products and transition state is computed to derive its reaction rate coefficient by means of (variational) transition state theory calculations. These temperature- and pressure-dependent reaction rate coefficient have great potential: using multi-scale methods (e.g. kinetic Monte-Carlo), they provide insights into the best conditions to grow single crystal diamond. Temperature, pressure and radical densities in the reactor influence both the rate and quality of the growth, and the versatility of the results presented herein allows to account for these factors. The approach used in this work can be generalised to any crystallographic orientation of diamond, and even to other semiconductor surfaces.

JuryProf. Thierry ARNOULD (UNamur), présidentProf. Benoît MUYLKENS (UNamur), secrétaireProf. Sébastien PFEFFER (Université de Strasbourg)Prof. René REZSOHAZY (UCLouvain)Prof. Catherine SADZOT (ULiège)Prof. Dr Benedikt KAUFER (Freie Universität Berlin)Prof. Carine VAN LINT (ULB)Dr Damien COUPEAU (UNamur),RésuméLes ARN existent sous diverses formes dans la cellule : les ARN messagers (ARNm), les ARN de transfert (ARNt) et ribosomaux (ARNr) et les petits ARN régulateurs (ARNsn, miARN, snoARN). Les ARN circulaires (ARNcirc) jouent également un rôle clé en servant de matrice pour la traduction, en inhibant des ARN régulateurs par interaction de séquence, ou en recrutant des protéines pour moduler leur activité.L’herpèsvirus des gallinacés, plus connu sous le nom de virus de la maladie de Marek (MDV), provoque un lymphome agressif chez le poulet, entrainant sa mort dans un délai de quelques semaines. Ceci est dû aux nombreux facteurs de virulence qu’il produit. Notamment, MDV produit un facteur de transcription, Meq, qui induit la transformation des cellules dans lesquelles le gène est exprimé. Ce projet de thèse s’intéresse à un ARNcirc dérivé de ce gène.Cette étude a d'abord identifié de nombreux ARNcirc encodés par MDV, notamment lors de la lymphomagenèse, à partir de quatre principaux locus viraux : l'OriLyt, vTR, LAT et Meq. Le développement du programme vCircTrappist a montré que des virus apparentés encodent également des ARNcirc similaires, reliant la circularisation des transcrits viraux à un mécanisme inconnu.Focalisée sur circMeq, l'étude a révélé que cet ARNcirc atténue la virulence de MDV, en contraste avec le rôle précédemment attribué à Meq. Cette conclusion repose sur l'inhibition sélective de circMeq ou de linMeq via des mutations dans le génome viral.Cette thèse a révélé des propriétés insoupçonnées du gène Meq, ouvrant la voie à des recherches futures, notamment des expériences in vivo pour explorer le rôle de circMeq dans la transmission de MDV. 

JuryProf. Alexandre MAUROY (UNamur), présidentProf. Timoteo CARLETTI (UNamur), promoteur et secrétaireProf. Malbor ASLLANI (Florida State University)Prof. Renaud LAMBIOTTE (Oxford Mathematical Institute)Prof. Filippo COLOMO (Università degli studi di Firenze)Prof. Christian WALMSLEY HAGENDORF (UCLouvain)RésuméFlocks of birds, people clapping in unison or the World Wide Web are some instances of complex systems in which a large number of entities interact with each other and produce some emergent phenomena. In this thesis, we pay special attention to two such complex systems, namely crowded random walks on networks, and domino tilings and vertex models. In recent years, networks and generalizations thereof have emerged as an efficient tool to model the pattern of interactions among a set of entities. Examples include social networks, transportation networks and ecological networks. A cornerstone of network science is the interplay between network structure and dynamics on networks. Among those dynamical processes, random walks play a central role. In the first part of this thesis, we study the dynamics of multiple random walkers moving across the nodes of the network, assuming the latter to be endowed with limited available space. We characterize, both analytically and numerically, the stationary states, and we subsequently apply the latter framework to a real ecological network. In the second part of the thesis, we move on to the study of the arctic curve phenomenon arising in domino tilings of double Aztec rectangles and configurations of the six-vertex model with partial domain wall boundary conditions. The latter two models manifest in the scaling limit a spatial phase separation between ordered regions and a central disordered region. We compute the arctic curve of the aforementioned models using the tangent method.

Consanguinity refers to the offspring produced from the union of two closely related individuals who share at least one common ancestor (Temaj et al. 2022). Some communities have high rates of consanguineous marriages, especially in the Middle East, where consanguinity rates of first-cousin marriages vary in Gulf countries from 20 to 50 % (Ben-Omran et al. 2020). This high rate of consanguineous marriages is due to cultural, geographical, historical, financial, political, or religious reasons (Temaj et al. 2022) (Ben-Omran et al. 2020).Consanguinity increases the chance/risk/probability to be homozygous for rare mutations in the general population (Temaj et al. 2022). These mutations can cause recessive autosomal pathologies that may be extremely rare known as rare diseases (Temaj et al. 2022). In many Middle Eastern populations, consanguineous relationships are very common, providing geneticists with a valuable source for discovering "new" genes and identifying their functions (Ben-Omran et al. 2020). Identifying these genes can help carry out diagnostic and predictive tests (genetic counseling) in affected families (Ben-Omran et al. 2020; Temaj et al. 2022). In some cases, understanding the pathophysiological mechanisms involved in diseases can also lead to new therapeutic strategies (Salzberg 2018).In recent years, the development of Next Generation Sequencing (NGS) technologies has led to a faster identification of genes involved in rare diseases (Lal et al. 2016). Sequencing the entire genome (Whole Genome Sequencing, WGS) or the exome (Whole Exome sequencing, WES) can be achieved quickly and inexpensively (Salzberg 2018).Rare diseases are Mendelian monogenic diseases, that result from specific pathogenic variants in single genes, called germline mutations. These mutations occurring in the coding or the non-coding regions in the gene, can be inherited in dominant, recessive, or X-linked transmission modes within a family (Tukker et al. 2021). Coding sequences, known as exons, directly encode the amino acid sequence of proteins essential for various cellular functions, including enzymatic reactions, cell signaling, and structural support. Pathogenic variants within coding sequences can lead to significant disruptions and alterations in the protein structure, function, and stability (Li et al. 2013).  However non-coding sequences that represents around 98% of the entire human genome, include introns, enhancers, promotors, and regulatory elements that regulate genes’ expression. The presence of a pathogenic variant in one of these regions can alter mRNA processing and gene expression and disrupt the delicate balance of gene regulation. REFERENCEWhile coding regions, constitutes around 1 to 2% of the entire genome, , the precise functions of non-coding regions are still unraveled (Moyon et al. 2022).Our project has two main objectives.A) Firstly, to identify the pathogenic variant responsible for a syndromic neurodevelopmental disorder (NDD) in a young boy from a consanguineous Lebanese family. This step was achieved in 2020 and our results were published in Clinical Genetics. Indeed, a homozygous stop gain mutation in the BOD1 gene (p.R151*) was identified and was shown to be involved in the disease observed in this family. BOD1 is a crucial protein that inhibits the PP2A-B56 phosphatase at the kinetochore, which regulates the recruitment of various proteins (such as PLK1: Polo like Kinase 1 ) to ensure proper chromosome orientation during mitosis (Porter et al. 2013). Additionally, BOD1 is a part of a cytosolic variant of the SET1B/COMPASS complex, which affects the expression of genes related to fatty acid metabolism (Wang et al. 2017). Studies in Drosophila have shown that BOD1 depletion in neurons causes synapse morphological abnormalities and learning defects (Esmaeeli-Nieh et al. 2016). Moreover, BOD1 was described to be responsible for ataxic-like behaviors in mice with conditional in what tissue? Knock-Out (KO) of exon 2 of this gene in the lobes IV-V of the cerebellum  (Liu et al. 2022). On another note, a homozygous nonsense mutation in BOD1 gene (p.R112*) was identified in two related Iranian females, who were diagnosed with moderate form of ID (Intellectual Disability) and primary/secondary amenorrhea (Esmaeeli-Nieh et al. 2016).B) Secondly, we aimed to study the effect of the p.R151* mutation in BOD1 gene on protein expression. To achieve this, we used the CRISPR-Cas9 genome editing technique to create a knock-in (KI) of the mutation in HEK293T cells. We then analyzed the effect of this mutation on the expression of Bod1 protein using Western blot technique. Furthermore, we wanted to investigate the physiological and developmental function of the BOD1 gene. For this purpose, we have generated a conditional knock-out cKO mouse model.

Entrez dans l’univers fascinant de la Space Week Namur 2024 ! Préparez-vous à un voyage extraordinaire à travers les étoiles et les mystères de l’espace. Voici le programme de cette semaine cosmique : Expositions “Objectif étoiles” : Avec cette exposition d'astrophotographie, plongez dans un océan d’étoiles scintillantes et laissez vous émerveiller par les secrets de notre galaxie. “Stellar Scape” :  Une aventure immersive où l'art et les sciences vous transporteront au cœur des paysages stellaires, où chaque étoile raconte une histoire. Événements "Mission ISS : Improvisation Space Station" :  Un spectacle de l’ImproNam, le kot-à-projet namurois d’improvisation théâtrale."Rencontre des astronautes" : Une chance unique pour les jeunes explorateurs de rencontrer des héros de l’espace et d’écouter leurs récits d’aventures au-delà de notre monde. “Mercredi des Savoirs” : Des ateliers interactifs pour les jeunes esprits curieux, prêts à découvrir les merveilles de la science.“Chill & Sciences” : Un moment convivial pour discuter avec un chercheur et un artiste, et explorer les mystères de l’univers. "Premier contact - Arrival" : Un ciné-rencontre proposé par le Caméo et Le Pavillon. "5 ans de l'Observatoire astronomique Antoine Thomas"Visites Visite de l’Observatoire astronomique Antoine Thomas : Une expédition guidée pour percer les secrets de l’observation astronomique et contempler les merveilles du cosmos. Ne manquez pas cette opportunité de plonger dans un univers fantastique et de partager des moments inoubliables avec des passionnés de tous horizons. Rendez-vous à Namur du 7 au 12 octobre 2024 pour la Space Week ! 🚀✨  Cliquez ici pour télécharger le programme et pour vous inscrire aux activités

Jury Prof. Benoît CHAMPAGNE (UNamur), présidentProf. Carmela APRILE (UNamur), secrétaireProf. Eric GAIGNEAUX (UCLouvain)Prof. Sonia FIORILLI (Politecnico di Torino)Prof. Wouter MARCHAL (UHasselt) Abstract Heterogeneous acid catalysts became over the years essential to our modern industrial world. Among the possible forms of solid materials with acidic properties, porous silica-based structures embedding active single-sites showed highly promising catalytic activity for various reactions. The insertion of heteroelements inside the SiO2 network is known to introduce a combination of Brønsted and Lewis acid sites which depends on the nature of the element and influences the catalytic properties of the solid. The present thesis investigates the link between the Brønsted/Lewis acid balance introduced by different elements (Al, Ga, In, Ti, Zr, Hf) inserted or finely dispersed in/onto the structure of extra-small silica nanospheres and the catalytic performances of the solids for two distinct biomass derivatives valorization reactions (i.e. conversion of glycerol to solketal and of ethyl levulinate to γ-valerolactone).The optimizations of the syntheses were particularly focusing on the insertion of the element inside the SiO2 matrix to maximize the number of acid sites. In-depth characterizations were conducted on the different substituted nanospheres to probe their morphological, structural, and textural features. A special attention was dedicated to the characterization of the surface acidity. These results were put into perspective with the catalytic performances of the materials. At the end of the investigations, we were able to explain the difference in terms of catalytic activity between the different studied solids and identify the optimal acid properties for the targeted reactions. The stability and recyclability of the best working solids were also assessed, an acute tuning of reaction conditions enabled to reach significatively high conversions, and their performances were tested in challenging conditions (i.e. close to crude feedstock).The knowledge unveiled through these investigations will give precious insight to design new silica-based catalysts with the appropriate acidity for a wide variety of acid-catalyzed reactions.

Jury Prof. Catherine MICHAUX (UNamur), PrésidenteProf. Yoann OLIVIER (UNamur), secrétaireProf. Piotr DE SILVA (Technical University of Denmark)Prof. Daniel ESCUDERO MASA (KULeuven)Prof. Benoît CHAMPAGNE (UNamur)Prof. Luc HENRARD (UNamur) Abstract Organic Light Emitting Diodes (OLEDs) are now a well-established technology in modern electronic devices, from flexible TV screens to lighting applications. Each time we use our smartphone, billions of tiny molecules are electrically stimulated to emit the colorful light reaching our eyes. The ability of these molecules to convert electricity into light is the core principle of an OLED, and understanding the mechanisms behind this process can help improve their performance.Recently, two new families of triangular-shaped organic molecular systems, known as Multi-Resonant (MR) and Inverted Singlet-Triplet (INVEST) compounds, have shown promising features for OLED applications.In my PhD research, I used computational chemistry to explore the quantum mechanical effects that define the peculiar features of these systems.The first part of my thesis focused on identifying the correct computational protocol to properly describe the energy and nature of the singlet and triplet excited states of the INVEST compounds, highlighting the importance of methods including double excitations.  With this information in our hands, we combined quantum chemistry and group theory to design new light-emitting INVEST compounds. Finally, we applied both static and dynamic approaches to describe the spin conversion processes in MR and INVEST systems, providing a comprehensive picture of their electronic and photophysical properties for next generation OLED applications.