HAL Portal UO (Université d'Orléans)
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Hardened properties of 3D printable mortars with full replacement of natural sand by recycled sand
No full textInternational audienceUsing recycled aggregates in concrete and mortar reduces environmental impact by minimizingboth natural aggregate consumption and construction waste disposal. 3D printing offers innovative, costefficient construction methods, but it heavily relies on cement and sand. This research aims to investigate the hard properties of 3D printing mortars made with 100% substitution of natural sand by recycled sand. The effects of sand substitution and 3D printingprocess on the hard properties of printable mortars are studied. The mechanical strength of moulded and printed specimens of printable mortars based on recycled sand were studied and compared with those made from a reference printable mortar based on natural sand. Additionally, the microstructure of mortars, namely the density of the interfacial transition zonein these specimens was analysed to understand the mechanical strength results. The results showed that both the incorporation of recycled sand and the 3D printing process had little effect on the mechanical strength. This could be attributed to the decrease in the density of the interfacial transition zone caused by both the incorporation of recycled sand and the mortarprinting process. Furthermore, the study investigated also the effect of incorporating recycled sand on autogenous, drying, and total shrinkage. It was observed that this incorporation reduces the autogenous shrinkage at an early age, while it increases both dry and total shrinkage
Développement de nouvelles céramiques transparentes dans le diagramme pseudo-ternaire Gd2O3-Ga2O3-Nb2O5 pour des applications LASER
No full textThis thesis is devoted to the development of novel transparent glass-ceramics within the Gd2O3 - Ga2O3 - Nb2O5 pseudoternary diagram. Such materials are expected to have low phonon energies, facilitating transparency in the near/mid infra-red with applications as new laser-gain media. The use of aerodynamic levitation (ADL) coupled with CO2 laser heating, permitted vitrification in the diagram for the first time. Additionally, the use of ADL facilitated the synthesis of new transparent ceramics by direct crystallisation of the supercooled liquid from the Gd3(GdxNb1-x)O7-x (0<x<0.4) solid solution, which itself was discovered as part of this work. Electron back scattering diffraction experiments revealed a highly unusual single-crystal like microstructure which explained the sample's transparency. From a crystallographic perspective, the basic fluorite cation sublattice is respected throughout the solid-solution. However, three types of short-range ordering are observed depending on the composition, as shown by synchrotron X-ray diffraction and single-crystal X-ray diffraction. The x = 0.4 member is a complex, but still transparent, nanocomposite due to coherent interfaces between ordered and disordered domains, as seen by atomic resolution HAADF-STEM.Cette thèse est consacrée au développement de nouvelles (vitro)-céramiques transparentes dans le diagramme pseudo-ternaire Gd2O3 - Ga2O3 - Nb2O5. Ces matériaux sont susceptibles de posséder de faibles énergies de phonon, facilitant la transparence dans l'infrarouge proche/moyen pour des applications en tant que nouveaux milieux amplificateurs laser. L'utilisation de la lévitation aérodynamique (ADL) couplée au chauffage par laser CO2 a permis la vitrification des certaines compositions au sein du diagramme pour la première fois. En outre, l'utilisation de l'ADL a facilité la synthèse de nouvelles céramiques transparentes par cristallisation directe du liquide surfondu dans la solution solide Gd3+xNb1-xO7-x (0<x<0,4), qui a elle-même été découverte dans le cadre de ce travail de thèse. Les expériences de diffraction des électrons rétrodiffusés ont révélé une microstructure du type monocristal très inhabituelle qui explique la transparence des échantillons. D'un point de vue cristallographique, le sous-réseau cationique de base de la fluorine est respecté dans toute la solution solide, mais il existe trois types différents types de mise en ordre à courte distance en fonction de la composition, comme le montrent la diffraction des rayons X synchrotron et la diffraction des rayons X sur monocristal. L'échantillon x = 0,4 est un nanocomposite complexe avec une interface cohérente entre les deux types de domaines qui assure la transparence, comme montré par HAADF-STEM
Maltodextrin-modified lipoplexes for enhanced mucosal penetration and efficient mRNA delivery
No full textInternational audienceEfficient delivery of messenger ribonucleic acid (mRNA) to mucosal tissues represents a promising approach for localized protein production in the nasal and respiratory tract. Here, we investigate the use of maltodextrin (MDX) as a surface modifier to enhance the delivery of mRNA-loaded histidylated lipoplexes (LXs) to airway epithelial cells. By reducing hydrophobicity, MDX facilitates better penetration through the mucus layer, enabling effective mRNA delivery. MDX-coated LXs improve mRNA delivery and expression in vitro by increasing cellular uptake and supporting sustained protein production. Additionally, MDX incorporation stabilizes in-house-formulated lipoplexes and modulates their interactions with mucin-covered cells. Notably, MDX-coated mRNA LXs display a four-fold increased transfection efficiency, and the protein expression is maintained up to 48 h post-transfection. Furthermore, intranasal administration of MDX-LXs results in efficient gene expression in vivo. Overall, our findings reveal that integrating MDX into mRNA lipoplexes is a promising strategy to advance nasal delivery for gene therapy and protein replacement applications
Explaining software and computational methods
No full texthttps://blog.khinsen.net/How can we document software and computational analyses in such a way that others can convince themselves of their validity, and build on them for their own work? The question has been around for many years, and a number of attempts have been made to provide partial answers. This post provides a brief review and describes my own tentative answer, inviting you to play with it. Explainable AI is a hot topic today
Improvement of tribological behavior of stainless steels in food cleaning process by sodium hydrogen carbonate
No full textInternational audienceStainless steel pumps in food industries are prone to seizure during sanitation operations. To understand the tribocorrosion phenomena induced during the cleaning routine, tribological and tribocorrosion tests were carried out using three inexpensive, eco-friendly domestic cleaning solutions: 8 % acetic acid, and 5 % sodium hydrogen carbonate. Some tests were conducted in demineralized water, which served as a reference medium. High friction and wear were observed with AISI 316 L stainless steel in vinegar and water, consistent with current observations in food cleaning processes. However, in sodium hydrogen carbonate, an unprecedented tribological behavior was recorded under specific test conditions. Worn surface analysis results indicate that this phenomenon is associated with the formation of a passive film composed of chromium oxides/hydroxides and iron oxides/hydroxides, with the emergence of a nickel-rich sublayer. The electrical activity of the passive film demonstrated its insulating behavior. Due to the synergistic interactions between the mechanical wear of the passive film and chemical reactions of AISI 316L stainless steel in sodium hydrogen carbonate, significant improvement in the frictional properties of AISI 316L has been found, which can play an important role in increasing the mechanical life of equipment and energy efficiency
Vérification Déductive de Programmes Réactifs Synchrones
No full textNational audienceCe poster décrit un travail en cours sur le développement d'une technique de vérification de propriétés de programmes réactifs. Ces programmes s'exécutant en continu afin de réagir à leur environnement, leur spécification doit décrire leur comportement dans le temps sous forme de propriétés temporelles.Le standard pour la vérification de ces propriétés est le model-checking: on considère des modèles qui représentent de manière abstraite le comportement des programmes. Ces modèles sont des systèmes de transitions finis. Comme la spécification caractérise l'ensemble des comportements corrects, le but est de vérifier de manière automatique que les comportements du programme sont inclus dans ceux de la spécification. Cependant, cette technique comporte deux inconvénients : Premièrement, il faut s'assurer que le modèle est bien une abstraction (sûr-approximation) du programme. Deuxièmement, les programmes complexes amènent rapidement à une explosion combinatoire ayant pour conséquence des durées de vérification déraisonnables. Après 30 ans d'existence, de nombreux travaux ont eu pour but de combattre ces faiblesses (model-checking symbolique, raffinement de modèle, parallélisme, heuristiques de recherche…). Cependant, à partir du moment où les programmes manipulent des domaines infinis, il n'est possible que de vérifier des sous-domaines finis.Contrairement au model-checking, la vérification déductive fait le lien direct entre la syntaxe du programme, sa sémantique et sa spécification. Elle nécessite de prouver un ensemble de théorèmes afin de garantir la conformité du programme. De plus, alors que le model-checking peut être vu comme une façon de faire du test, généralement incomplet, la preuve permet de mener un raisonnement sur l'entièreté du domaine, qu'il soit fini ou infini. Il n'est néanmoins pas possible en général d'espérer trouver automatiquement une preuve. Aussi, la vérification déductive a principalement été étudiée dans le cadre de programmes qui terminent, c'est-à-dire pour lesquels on ne s'intéresse pas au comportement dans le temps.Avec notre approche, nous désirons adapter la vérification déductive aux programmes réactifs : à partir d'un programme annoté, un ensemble de théorèmes sont générés. Ces théorèmes peuvent être prouvés automatiquement où par l'utilisateur, l'intention étant de ne faire intervenir celui-ci que pour des théorèmes non triviaux nécessitant une connaissance profonde du programme à vérifier.</div
Going for robustness: science
No full texthttps://blog.khinsen.net/This is a follow-up to my earlier post entitled "Going for robustness", focusing on scientific research
Going for robustness
No full texthttps://blog.khinsen.net/I suspect that most people in the Western world (at least) are realizing that we are living in interesting times. News of floodings, droughts, and wildfires are ever more frequent. We hear that this is due to climate change, which most governments promise to fight, but don't. Our economies keep growing, but our quality of life is not improving. Digital tools are ever more prominent in our lives, but don't make us happy either
Etude de cas : Les enjeux de l’IA au service de la gestion des risques dans un SDIS
No full textInternational audienc
Negative moment of inertia of large- gluons on a ring
No full textInternational audienceWe study SU() Yang-Mills theory in dimensions at finite temperature on a spatial ring that rotates uniformly in a plane. We show that the effect of rotation results only in a simple kinematic enhancement of the gauge coupling , which becomes rescaled by a Lorentz factor corresponding to the tangential rotational velocity of the ring. Using well-established analytic results in Yang-Mills theory in the 't Hooft limit of an infinite number of colors, we demonstrate that the moment of inertia of the large- gluon plasma on the ring is negative. This counterintuitive conclusion is, however, in agreement with recent first-principle numerical simulations of hot dimensional SU(3) Yang-Mills theory that also reported a negative moment of inertia for gluon plasma in an experimentally relevant window of temperatures above the deconfinement transition. Furthermore, we argue that our picture provides a qualitative explanation for three other intriguing features observed in lattice simulations of vortical QCD: the emergence of a spatially inhomogeneous mixed phase, the inconsistency of its spatial structure with a standard picture dictated by the Tolman-Ehrenfest law, and the enhancement of the critical deconfining temperature by rotation