A new approach for a microparts feeding system based on inertial force.

International audienceThis paper deals with the presentation of a new microparts feeding system based on inertial force and able to move microcomponents with various shapes and sizes. It is a part of our microfactory project, in which different modular elements work together in order to perform assembly tasks [1], [2], [3], [4]. We present the design and the experimental results of this new type of feeder based on the concepts of modularity and flexibility

Practical characterisation of the friction force for the positioning and orientation of Micro-Components.

International audienceThis paper deals with the description of a method for the measurement of friction force between a very small object (80 to 300 μm) and a support. The goal is to design a feeder based on controlled mechanical vibrations in order to drive microcomponents by breaking the friction force. The contact model is based on the Hertz theory and the Greenwood- Williamson multi-asperity model. The amplitude of the static friction force is measured in a clean environment with an AFM (Atomic Force Microscope) whose cantilever is placed in the vertical position. Using this setup and the modeling, we have estimated the interfacial shear stress between the microcomponent and the support

Recommendations for the application and follow-up of quality controls in medical laboratories

This is a translation of the paper “Recommendations for the application and follow-up of quality controls in medical biology laboratories” published in French in the journal Annales de Biologie Clinique (Recommandations pour la mise en place et le suivi des contrôles de qualité dans les laboratoires de biologie médicale. Ann Biol Clin (Paris). 2019;77:577-97.). The recommendations proposed in this document are the result of work conducted jointly by the Network of Accredited Medical Laboratories (LABAC), the French Society of Medical Biology (SFBC) and the Federation of Associations for External Quality Assessment (FAEEQ). The different steps of the implementation of quality controls, based on a risk analysis, are described. The changes of reagent or internal quality control (IQC) materials batches, the action to be taken in case of non-conform IQC results, the choice of external quality assessment (EQA) scheme and interpretation of their results as well as the new issue of analyses performed on several automatic systems available in the same laboratory are discussed. Finally, the concept of measurement uncertainty, the robustness of the methods as well as the specificities of near-patient testing and rapid tests are described. These recommendations cannot apply for all cases we can find in medical laboratories. The implementation of an objective alternative strategy, supported with documented evidence, might be equally considered

Conception et commande de systèmes d'alimentation en composants de petites tailles pour micro-usine d'assemblage de haute précision.

Feeding function is a major problem in the design of the production systems. A feeder has to guarantee the position and the orientation of the components it supplies to the assembly system. However, the more the objects are small the more the required precision is high. The presented works have been realised for the feeding of components of which range of size is from some millimetres to hundred of microns. Moreover, the design of the feeding systems has been thought in order to be used with a large range of size of components. The first contribution of the thesis consisted in elaborating a feeding strategy associating high accuracy and flexibility for millimetre-length components. This work has been done as a contribution for an European project of the 6th PCRD, the IP EUPASS (Evolvable Ultra Precision Assembly SystemS). To meet the standard of EUPASS, the proposed feeding system is flexible (it can transport all the test-bed components), modular (it is ?plug and produce?), highly accurate (micrometer range) and based on an opened control architecture. The second part of the work is dedicated to hundred micrometer size components. The objective was to move several kind of micro-objects on a surface until a given position. We have used controlled mechanical vibrations to move micro-objects by inertia. Because the friction force is not well characterized at the micrometer level, we have firstly proposed a method to calculate it in the case of a planar contact between the component and the surface of the feeder. Knowing this force, we where able to control precisely the vibrations of the feeding system in order to move the component. Using this method, a step by step displacement is obtained. The steps can be controlled to give the resolution of the system. Finally, a visual servoing allows controlling the movement of micro-objects until their final position.L'alimentation en composants est un problème majeur dans la conception des systèmes de production et plus particulièrement d'assemblage. Un système d'alimentation doit garantir la position et l'orientation des composants qu'il fournit au système d'assemblage, quelle que soit la taille des composants. En revanche, le niveau de précision sera généralement d'autant plus important que les composants sont petits. Nos travaux ont été réalisés dans le contexte de l'alimentation en composants de taille millimétrique à microscopique avec des objectifs de modularité et de haute précision de positionnement. La première contribution de la thèse a consisté à élaborer une stratégie pour l'alimentation de haute précision en composants millimétriques pour une architecture ouverte, flexible et standardisée, proposée par un projet européen EUPASS (Evolvable Ultra Precision ASembly System). Un système standard a ainsi été développé. Il est modulaire, reconfigurable pour différents types de minicomposants et permet leur maintien micrométrique. Sur la base de ces travaux, nous avons étendu notre étude aux systèmes de micro-assemblage (microusine). L'objectif était de déplacer dans un plan des micro-objets jusqu'à une position donnée. L'idée retenue se fonde sur l'utilisation des vibrations pour entraîner ces micro-objets par inertie. Il a donc été nécessaire de caractériser les interactions entre la surface du système d'alimentation et la surface du micro-objet. Pour cela nous avons élaboré une méthode pour évaluer directement la force concernée qui est la force de friction. Le contrôle des vibrations du système a ensuite été conçu. Le pas de déplacement d'un micro-objet en fonction de ses caractéristiques est alors maîtrisé. Enfin, une boucle d'asservissement permet de contrôler le déplacement des micro-objets jusqu'à une position consigne

Etude de l'ordre local dans les biopolymères par RMN du solide (applications aux traitements physico-chimiques de l'amidon)

L'acquisition de spectres RMN haute résolution du 13C sur des substrats amylacés bien définis - senù-cristallins (natifs) et recristallisés - et leurs décompositions spectrales ont montré l'existence de trois phases dans les anùdons natifs (amorphe, intermédiaire et cristalline) et de deux phases dans les amyloses recristallisées, indépendamment du type cristallin. Les rôles plastifiant/structurant de l'eau ont été nùs en évidence sur chacune des phases. La comparaison des taux de cristallinité déterminés par RMN et diffraction des rayons X montre que l'eau agit simultanément à deux échelles: une locale (nm) et une microscopique (mm). La multiplicité de phases non cristallines nous a alors amené à initier la première étude expérimentale de caractérisation locale des structures amorphes à base d'amidon. Sur des substrats amorphes préparés à partir 'd'amidon ou de ses constituants par différentes procédures, l'acquisition de spectres RMN haute résolution du 13C et leurs décompositions spectrales ont montré la nature hétérogène mais reproductible de ces structures amorphes. En effet, seuls 4 types de conformations bien identifiables et stables de liaisons a(I-4) composent ces substrats. De plus, deux de ces familles de conformations sont plus particulièrement sensibles à l'histoire de l'échantillon (méthode de préparation et structure intrinsèque primaire). En complément de la caractérisation par décomposition spectrale, une approche dynamique a été réalisée. Pour les substrats amorphes étudiés, la courbe d'aimantation en fonction du temps de contact en polarisation croisée de chacune des raies élémentaires nùses en évidence a été construite. La simulation de ces courbes nécessite l'utilisation d'un modèle de polarisation croisée à deux réservoirs de protons. Couplées à des expériences de RMN 2D WISE, la détermination et l'interprétation des paramètres du modèle à deux réservoirs de protons permettent d'obtenir des informations sur la répartition des molécules d'eau à l'intérieur des échantillons. De plus, cette approche dynamique a permis de confirmer certains résultats obtenus par décomposition spectrale. -Enfin, des calculs ab initio (Gaussian 98) ont été réalisés pour prédire l'anisotropie de déplacement chimique des carbones en fonction des angles de torsion (phi, psi) de la liaison glycosidique a(1-4). Nous avons également déterminé expérimentalement cette anisotropie par des expériences de RMN 2D de recouplage de déplacement chinùque. La comparaison de ces anisotropies a permis d'estimer les valeurs des angles glycosidiques associées à différents types de liaisons a(I-4). Les premiers résultats issus de cette méthode ont été discutés.LE MANS-BU Sciences (721812109) / SudocSudocFranceF

A generic approach for a micro parts feeding system.

International audienceThe paper propose a new approach in order to design a generic microparts feeder. The method based on a classification scheme allows to emerge the principal characteristics of each studies solutions. The different criteria take into account the specifities of the micro world and moreover the main characteristics for the feeding functions. Thus, we analyse three systems and confront them to find the generic and flexibility aspects

The IbeA protein from adherent invasive Escherichia coli is a flavoprotein sharing structural homology with FAD‐dependent oxidoreductases

International audienceInvasion of brain endothelium protein A (IbeA) is a virulence factor specific to pathogenic Escherichia coli. Originally identified in the K1 strain causing neonatal meningitis, it was more recently found in avian pathogenic Escherichia coli (APEC) and adherent invasive Escherichia coli (AIEC). In these bacteria, IbeA facilitates host cell invasion and intracellular survival, in particular, under harsh conditions like oxidative stress. Furthermore, IbeA from AIEC contributes to intramacrophage survival and replication, thus enhancing the inflammatory response within the intestine. Therefore, this factor is a promising drug target for anti‐AIEC strategies in the context of Crohn's disease. Despite such an important role, the biological function of IbeA remains largely unknown. In particular, its exact nature and cellular localization, i.e., membrane‐bound invasin versus cytosolic factor, are still of debate. Here, we developed an efficient protocol for recombinant expression of IbeA under native conditions and demonstrated that IbeA from AIEC is a soluble, homodimeric flavoprotein. Using mass spectrometry and tryptophan fluorescence measurements, we further showed that IbeA preferentially binds flavin adenine dinucleotide (FAD), with an affinity in the one‐hundred nanomolar range and optimal binding under reducing conditions. 3D‐modeling with AlphaFold revealed that IbeA shares strong structural homology with FAD‐dependent oxidoreductases. Finally, we used ligand docking, mutational analyses, and molecular dynamics simulations to identify the FAD binding pocket within IbeA and characterize possible conformational changes occurring upon ligand binding. Overall, we suggest that the role of IbeA in the survival of AIEC within host cells, notably macrophages, is linked to modulation of redox processes

O-acetylated gangliosides: Structure, biosynthesis, immunogenicity, functions and their potential for cancer immunotherapy

International audienceSialic acid O-acetylation is a developmentally regulated modification of gangliosides implicated in ontogeny and tumor progression. Their existence has been underestimated in the past because of their alkali-labile nature and their transient expression. New data indicates, however, that O-acetylated gangliosides perform important function in tumor malignancy. Best studied O-acetyl-GD3 blocks the pro-apoptotic activity of GD3 and promotes survival of cancer cells. In acute lymphoblastic leukaemia cells, O-acetyl-GD3 expression level also correlates with survival and drug resistance. The recent identification of the enigmatic O-acetyltransferase opens new experimental approaches for designing novel effective therapeutics targeting drug-resistant cancer cells in acute lymphoblastic leukaemia. In addition, O-acetylated gangliosides expressed at the tumor cell surface are accessible for specific monoclonal antibodies to inhibit cell growth, to induce apoptosis, and to inhibit tumor metastasis formation. Thus, passive immunotherapy using murine or murine/human chimeric monoclonal anti-O-acetylated ganglioside antibodies are currently being investigated. Particularly, targeting of O-acetyl-GD2 could reduce the acute toxicities currently associated with anti-GD2 therapeutic antibodies. This review summarizes the molecular mechanisms involved in the biosynthesis and the expression of O-acetylated gangliosides and presents the new experimental approaches that allow the characterization of their importance in tumor progression. The different strategies used by different teams to develop specific monoclonal antibodies against these poorly immunogenic glycolipids for therapeutic application are also discussed