Résultats de recherche

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.

Rejoignez-nous lors de cette journée scientifique organisée en l'honneur du Professeur Yves Poumay, afin de célébrer sa remarquable carrière de chercheur dans le domaine de la biologie et physiopathologie cutanée. Au programme: des conférences scientifiques données par des orateurs invités, des communications orales et des posters présentés par des jeunes chercheurs, une rétrospective de la carrière d’Yves Poumay, des discours et, pour clôturer en beauté, un drink festif suivi d’un walking dinner.Un appel à abstract est ouvert ! Les jeunes chercheurs actifs dans le domaine de la recherche cutanée sont invités à soumettre un abstract pour une courte communication orale ou la présentation d'un poster.  Plus d'infos sur la page web sur le site de l'Institut NARILIS (voir ci-dessous). Conférenciers invités •    Laure DUMOUTIER, UCLouvain, Institut de Duve•    Gilles LEMAITRE, Université d'Evry/Paris Saclay, Laboratoire de Génomique et Radiobiologie de la Kératinopoïèse•    Bernard MIGNON, Université de Liège, Unité de Recherche de la Faculté de Médecine vétérinaire (FARAH)•    Abdallah MOUND, Université Hassan II de Casablanca, Faculté de Médecine et de Pharmacie•    Arjen NIKKELS, Université de Liège, CHU du Sart Tilman, Service de dermatologie•    Michel SIMON, Université de Toulouse, Institut toulousain des maladies infectieuses et inflammatoires (INFINITY)Nos sponsorsLabconsult | Technigen | MLS | CliniSciences Le comité organisateur Charles Nicaise, Catherine Lambert de Rouvroit, Emilie Faway, Bastien Tirtiaux, Eléa Denil et Valérie De Glas En savoir plus

Programme 8:50 | Welcome, registration, and poster setup9:20 | Welcome speechFirst morning session 9:30 | Vladimir N. Uversky - University of South Florida, USA - "Dancing protein clouds: strange biology and chaotic physics of intrinsically disordered proteins" 10:15 | Marie Skepö - Lunds Universitet, Sweden - "Structural and conformation properties of IDPs: computer simulations in combination with experiments"       11:00 | Coffee breakSecond morning session11:30 | Peter Tompa - Vrije Universiteit Brussel, Belgium - "Fuzzy interactions of IDPs driving biomolecular condensation"12:15 | Sonia Longhi - Aix-Marseille Université, France - "Intrinsic disorder, phase transitions, and fibril formation by the Henipavirus V and W proteins"   13:00 | Lunch and poster sessionAfternoon session14:30 | Sigrid Milles - Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Germany - "Intrinsically disordered proteins in endocytosis: an NMR and single molecule fluorescence perspective"     15:15 | Jean-François Collet - Université Catholique de Louvain, Belgium - "How disorder controls the transport of lipoproteins in the cell envelope of Gram-negative bacteria"    16:00 | Closing speech16:10 | Networking Beer Time at "Le Chapitre"VenueUniversity of Namur, auditorium Pedro Arrupe (PA02), rue de Bruxelles, 65-67 - 5000 Namur (#21 on the campus map) Download the programme (PDF) Download the campus map Registration guidelines Registration feeStudents (PhD students included): 25 €Seniors: 40 €Payment - Bank transferPayable before 6 December on the account:Name: Université de Namur – ASBLIBAN: BE10 2500 0740 2704BIC: GEBABEBB Please mention your name/CPO4136330 /e-mail in the payment communication. Abstract guidelines Send us your abstract before 6 December by email: pdid.meeting@unamur.be Format: Word document, maximum 1 page A4, Times New Roman  Registration All deadlines (registration, payment, abstracts) : 6 December 2024

JuryProf. Francesca CECCHET (UNamur), présidenteProf. Luc HENRARD (UNamur), promoteur et secrétaireProf. Gian-Marco RIGNANESE (UCLouvain), co-promoteur Prof. Vincent LIEGEOIS (UNamur)Prof. Xavier GONZE (UCLouvain) Prof. Humbert BERNARD (Université de Nantes)AbstractSensing technologies are critical across scientific, industrial, and medical domains, enabling the detection and analysis of various (bio)chemicals. Vibrational spectroscopies, such as Raman spectroscopy and infrared absorption spectroscopy, offer powerful and non-destructive means to characterize these molecular structures and their interactions. However, their application is often limited by inherently small cross-sections, curbing the analysis of low concentration. Surface-enhanced vibrational spectroscopies (SEVS), including surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA), address these limitations by using electromagnetic field enhancements associated with localized surface plasmon resonances (LSPR) in nanostructured metal substrates. The resonant coupling between plasmons and molecular vibrations significantly enhances spectroscopic signals, facilitating trace molecule detection and real-time chemical reaction monitoring.Despite experimental success, the theoretical understanding of SEVS remains incomplete, presenting a challenge in simulating plasmonic responses and molecular vibrational modes within a unified framework. This thesis aims to bridge this gap using a combination of Discrete Dipole Approximation (DDA) and Self-Consistent Field Hartree-Fock (SCF-HF) methods, focusing on SEIRA to complement existing SERS studies.Our work begins with isolated gold particles analysed via DDA, benchmarked against Mie theory. We then explore coupled disk systems, revealing hot spots and polarization-dependent extinction cross-sections. The study of nanorods with infrared plasmonic resonances demonstrates that the observed SEIRA effect is driven by the strong coupling between plasmon excitations and molecular vibrations, rather than by the local field response of molecules. This insight shifts the focus towards designing plasmonic systems sensitive to environmental changes rather than merely enhancing the local field.RésuméLes technologies de détection sont cruciales dans les domaines scientifique, industriel et médical, permettant la détection et l'analyse de divers produits chimiques. Les spectroscopies vibrationnelles, telles que la spectroscopie Raman et l'absorption infrarouge, offrent des moyens puissants de caractériser les structures et les interactions moléculaires. Cependant, leur application est souvent limitée par des sections efficaces intrinsèquement petites, en particulier pour les molécules à faible concentration ou dans des environnements complexes. Les spectroscopies vibrationnelles exaltées en surface (SEVS), incluant la spectroscopie Raman exaltée en surface (SERS) et l'absorption infrarouge exaltée en surface (SEIRA), répondent à ces limitations en utilisant les renforcements du champ électromagnétique associés aux résonances plasmoniques de surface localisées (LSPR) dans les substrats métalliques nanostructurés. Le couplage résonant entre les plasmons et les vibrations moléculaires améliore considérablement les signaux spectroscopiques, facilitant la détection de molécules à l'état de trace et la surveillance en temps réel des réactions chimiques.Malgré leur nombreuse preuve expérimentale, la compréhension théorique des SEVS reste incomplète, posant un défi pour la simulation des réponses plasmoniques et des modes vibratoires moléculaires dans un cadre unifié. Cette thèse vise à combler cette lacune en utilisant une combinaison de l'Approximation des Dipôles Discrets (DDA) et de la méthode deHartree-Fock (SCF-HF), en se concentrant sur le SEIRA pour compléter les études existantes sur le SERS.Notre travail commence par l'analyse de particules d'or isolées via DDA, comparées à la théorie de Mie. Nous explorons ensuite des systèmes de disques couplés, révélant des hot spots et des sections efficaces d'extinction dépendant de la polarisation. L'étude de nanorods avec des résonances plasmoniques infrarouges démontre que l'effet SEIRA observé est dû à un fort couplage entre les excitations plasmoniques et les vibrations moléculaires, plutôt qu'à la réponse au champ local des molécules. Cette découverte suggère d’orienter la conception de systèmes plasmoniques vers une sensibilité aux changements environnementaux plutôt que vers le simple renforcement du champ local. 

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.

Comprendre et lutter contre la sécrétion anormale de protéines et combattre l’enveloppe des bactéries pathogènes : tels sont les deux axes de deux nouveaux projets UNamur sélectionnés dans le cadre du  7ème appel à projets FRFS-Welbio. Parmi les 22 dossiers sélectionnés, Alison Forrester, chercheuse qualifiée FNRS, a obtenu un Starting Grant et Xavier De Bolle, Professeur ordinaire, a obtenu un Advanced Grant. Ils sont tous les deux Investigateurs du WEL Research Institute et membres du Namur Research Institute for Life Sciences (NARILIS). 

La CIAP propose un service gratuit de consultation méthodologique. Cet accompagnement se fait sous la forme d’entretiens individuels en présentiel ou via Teams. Ce service est ouvert à tous les étudiants de l’Université de Namur, quelles que soient leur orientation et leur année d’études.