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Étude pharmacocinétique de l'amoxicilline durant la gestion, sur le modèle de la brebis gravide
Get PDFL’amoxicilline est un antibiotique fréquemment prescrit durant la grossesse chez la femme, mais les connaissances sur sa pharmacocinétique et sa distribution au fœtus sont limitées. L’objectif de cette thèse était donc d’étudier la pharmacocinétique de l’amoxicilline chez la brebis gravide. Des prélèvements sanguins maternels et fœtaux ont été réalisés sur 39 brebis gravides proches du terme, 24 et 48h après l’administration par voie intramusculaire d’amoxicilline longue action (LongAmox®). Un échantillon de liquide amniotique a également été prélevé 24h après l’injection. A partir des dosages d’amoxicilline réalisés sur ces milieux, une extrapolation a été proposée pour estimer les concentrations en amoxicilline qui pourraient être atteinte dans le plasma fœtal lors de deux protocoles d’antibiothérapie proposés chez la femme enceinte. Les concentrations ont ensuite été comparées aux concentrations minimales inhibitrices des principaux agents pathogènes
The control of hydroxyl density on glass particulates surface: Application to anionic polymerization of polyamide 6
Get PDFMonomer polymerization after the impregnation of reinforcements is a relevant option for the manufacturing of thermoplastic composites by liquid processes (infusion or RTM). In the case of polyamide 6 (PA6) synthesized by this process, the system is composed of the monomers, the catalyst, and the activator, which react within the fibrous environment. Therefore, controlling the chemistry of the fiber surface is crucial because it influences not only the polymerization and crystallization processes, but it also controls the fiber-matrix adhesion and the resulting mechanical properties. However, the hydroxyl groups typically present on the glass fiber surface inhibit the polymerization process. The objective of this project is to adapt and control the surface chemistry of glass particulate reinforcements in order to promote the polymerization and crystallization processes of PA6. This work was carried out with glass microbeads comparable in size to the diameter of glass fibers. First, the evolution of the hydroxyl groups surface density on the glass beads, as a function of calcination time, was monitored by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The hydroxyl groups surface density was then tuned in order to allow thesynthesis of anionic polyamide 6 (PA6), which was monitored by differential scanning calorimetry (DSC). Next, in order to further promote the polymerization and crystallization of PA6, and to improve interfacial adhesion between the PA6 and glass particulates, the grafting process of an amino-silane coupling agent at the particulates surface was investigated by TGA and FTIR. The results demonstrate that the competition between re-hydroxylation and condensation of the silane on the surface during the grafting process needs to be carefully balanced in order to maintain fast polymerization kinetics, as revealed by DSC analysis. Overall, the systematic methodology presented in this work can be adapted for various combinations of reactive resins and solid fillers, allowing for the preparation of high performance (nano)composite materials
Hardening Techniques for Image Sensors
No full textDr. Vincent Goiffon, ISAE-SUPAERO, University of Toulouse, will provide an overview of the main radiation-induced degradations in solid state image sensors and present mitigation techniques to improve their radiation hardness and enable their use in harsh radiation environments. Among the wide variety of radiation effects relevant for pixel arrays and detectors, radiation-induced leakage currents in PN junctions are by far the main factor limiting the performances of these mixed signal integrated circuits when exposed to fields of high energy particles. How Total Ionizing Dose affects these leakages and how design and process optimizations can reduce the dark current in irradiated sensors will be discussed. What can enhance or reduce the sensitivity of an image sensor to more specific effects such as displacement damage and radiation induced random telegraph signal will also be addressed. The presentation will primarily focus on the CMOS Image Sensor technology, but will also explore the applicability of the presented concepts to other solid state image sensor technologies, as well as the similarities with other leakage sensitive devices such as DRAMs. This presentation will conclude by an overview of the relevant pixel radiation hardening techniques to use depending on the application requirements: from Earth observation space instruments to the exploration of the Jovian system and nuclear fusion instrumentation
Network hydration, ordering and composition interplay of chemical vapor deposited amorphous silica films from tetraethyl orthosilicate
Get PDFThe chemical or mechanical performance of amorphous SiO2 films depend on intrinsic physicochemical properties, which are intimately linked to atomic and molecular arrangements in the Si–O–Si network. In this context, the present work focuses on a comprehensive description of SiO2 films deposited from a well-established chemical vapor deposition process involving tetraethyl-orthosilicate, oxygen and ozone, and operating at atmospheric pressure in the range 400–550 °C. The connectivity of the silica network is improved with increasing the deposition temperature (Td) and this is attributed to the decreased content of hydrated species through dehydration-condensation mechanisms. In the same way, the critical load of delamination increases with increasing Td thanks to the silicon substrate oxidation. The utilization of a O2/O3 oxidizing atmosphere involving the oxidation of intermediates species by O2, O3 and O., allows increasing the deposition rate at moderate temperatures, while minimizing carbon, H2O and silanol contents to extremely low values (4.5 at.% of H). The SiOx stoichiometry and Td interplay reveals two distinct behaviors before and above 450 °C. The best corrosion resistance of these films to standard P-etching test is obtained for the minimum silanol content and the best network molecular ordering, with an etching rate of 4.0 ± 0.1 Å/s at pH = 1.5. The elastic modulus and hardness of the films remain stable in the investigated range of deposition temperature, at 64.2 ± 1.7 and 7.4 ± 0.3 GPa respectively, thanks to the low content in silanol groups
Anomaly detection for replacement model in hyperspectral imaging
Get PDFIn this paper we consider Anomaly Detection in the hyperspectral context, and we extend the popular RX detector, initially designed under the standard additive model, to the replacement model case. Indeed, in this more realistic framework, the target, if present, is supposed to replace a part of the background. We show how to estimate this background power variation to improve the standard RX scheme. The obtained Replacement RX (RRX) is shown to be closed-form and outperforms the standard RX on a real data benchmark experiment
Towards the moon and beyond: preparing for the future of cislunar and solar system exploration
Get PDFA new era of space exploration has begun, as the Artemis program marks a fundamental step for human spaceflight. All eyes are on the Moon: NASA has recently proposed a Lunar Orbital Platform-Gateway concept as the basis for future space exploration. The Moon and the cislunar environment will serve as training grounds for extra-terrestrial settlements, hosting the next developments of the space industry. Such ambitious objectives require a dedicated framework of innovative methods and operational strategies. Researchers of the Space Advanced Concepts Laboratory (SaCLaB) at the Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO) develop state of the art tools and methodologies to push the limits of cislunar exploration. To prepare for tomorrow, one must strive for innovation at all stages of mission design: this paper discusses the vision of the SaCLaB about access to the cislunar environment and to the Moon, in-orbit operations and exploitation of lunar resources. Rethinking our journey to the Moon and beyond is an essential part of the equation. Natural properties of multi-body dynamics create low-energy transport pathways to our natural satellite and further regions of the solar system. Near Rectilinear Halo orbits, future hosts of the Gateway, have stability and accessibility properties suited for human presence and staging missions, but they require dedicated system dynamics methodologies for mission analysis and operational purposes. Low-thrust propulsion will play a major role to ensure more sustainable mission profiles for cargo, maintenance, and resupplying missions to lunar settlements. In-orbit operations and servicing are essential for repeated lunar access and surface exploration. Rendezvous and Docking operations are paramount for assembly, servicing, and crew/cargo exchange activities. Station-keeping and orbit maintenance in Lagrangian point orbits are also challenges to be overcome for extended human presence in the region. Multi-body dynamics theory and autonomous guidance and control systems can ensure that such operations are optimized in terms of fuel consumption and duration while complying with the safety requirements and standards of tomorrow. Repeated access to the lunar surface requires new transfer vehicles and modules dedicated to transporting crew and cargo between lunar settlements and lunar orbits. Such systems will benefit greatly from recent advances in multidisciplinary optimization and reusability studies. Finally, lunar surface operations, logistics for ISRU, energy management, and life support systems are presented as building blocks for a future lunar settlement
Immersed granular collapse: from viscous to free-fall unsteady granular flows
Get PDFThe collapse of a granular column in a liquid is investigated using numerical simulations. From previous experimental studies, it has been established that the dynamics of the collapse is mostly influenced by the Stokes number St, comparing grain inertia and viscous fluid dissipation, and the initial volume fraction of the granular column φi. However, the full characterization of the collapse in the (St, φi) plane is still missing, restricting its modelling as a physical process for geophysical applications. Only numerical tools can allow the variation over the parameter space (St, φi) that is hardly reachable in experiments as well as a full description of the granular phase that plays a major role in dense granular flows. For this purpose, a dedicated numerical model is used including a discrete element method to resolve the granular phase. The specific objectives of the paper are then twofold: (i) the characterization of the dynamics of the collapse and its final deposit with respect to (St, φi) to complement available experimental data, and (ii) the description of the granular rheology according to these two dimensionless numbers including dilatancy effects. A simple predictive model stems from the obtained results, allowing one to explain the evolution of the final deposit with (St, φi)
Detection of precursors of combustion instability using convolutional recurrent neural networks
Get PDFMany combustors are prone to Thermoacoustic Instabilities (TAI). Being able to avoid TAI is mandatory to efficiently operate a system without sacrificing neither performance nor safety. Based on Deep Learning techniques, and more specifically Convolutional Recurrent Neural Networks (CRNN)1, this study presents a tool able to detect and translate precursors of TAI in a swirled combustor for different fuel injection strategies. The tool is trained to use only time-series recorded by a few sensors in stable conditions to predict the proximity of unstable operating points on a mass flow rate / equivalence ratio operating map, offering a real-time information on the margin of the system versus TAI. This allows to change operating conditions, and detect the directions to avoid in order to remain in the stable domain
Degradation of ibuprofen by photo-based advanced oxidation processes: exploring methods of activation and related reaction routes
Get PDFSeveral homogeneous photo-based advanced oxidation processes - namely photolysis, photo- oxidation and photo-Fenton oxidation - were investigated for the elimination of ibuprofen in water. The effects of several operating parameters, such as the lamp type (low or medium pressure mercury, xenon-arc), the concentration of hydrogen peroxide (0.5 to 7 times the stoichiometric amount required for mineralization) and the concentration of Fenton reagent, were quantified. Photo-Fenton oxidation was also combined with low-frequency sonication to investigate possible synergistic interactions. Ibuprofen degradation under ultraviolet photolysis and ultraviolet/hydrogen peroxide oxidation followed pseudo-first-order kinetics with respect to the pollutant concentration and the apparent rate constant increased with lamp power (6-10 W) and oxidant concentration. Photo-Fenton oxidation under ultraviolet light (L1 lamp, 254 nm, 6 W) and visible light (L2 lamp, 360-740 nm, 150 W) led to complete ibuprofen removal after 3 h, but the mineralization yield of the L1/Fenton process (82%) was higher than that of the L2/Fenton process (59%) because of the effects of ultraviolet/hydrogen peroxide oxidation in the former. Coupling L2/Fenton with sonication improved the degradation rate of the molecule at low Fenton reagent concentration, but the beneficial effect of ultrasound on ferrous iron regeneration vanished when the iron to ibuprofen molar ratio was close to 1. An overall reaction scheme for ibuprofen degradation is proposed based on the transformation products detected during these processes
Raffinement adaptatif du processus d'assimilation de données par méthodes de Kalman d'ensemble pour des problèmes non linéaires.
Get PDFLe filtrage par filtre de Kalman d'ensemble (EnKF) pour des systèmes dynamiques non-linéaires nécessite de raffiner l'algorithme initial pour obtenir de bonnes performances. Les indicateurs de qualité de prévision « Forecast Sensitivity Observation Impact » (FSOI) permettent ces améliorations. En suivant cette voie, cette thèse propose d'utiliser et comparer de nouveaux indicateurs inspirés des FSOI, pour formuler des stratégies d'assimilation consistant à sélectionner les instants des étapes d'analyse et le nombre d'observations assimilées pour chacune. Les indicateurs a priori se calculent à l'arrivée d'une observation et les indicateurs a posteriori après l'étape d'analyse. Leurs coûts numériques sont calculés et discutés, montrant une utilisation possible pour des algorithmes type ETKF. Les indicateurs sont testés sur des systèmes emblématiques de petite dimension et un système industriel. Nous montrons la possibilité de sélectionner pour l'assimilation les observations les plus importantes, et les instants d'assimilation les plus opportuns pour un système fortement observé. Cela valide les indicateurs pour des essais sur des systèmes industriels plus complexes. Des perspectives sont données pour leur insertion dans les filtres d'ensemble itératifs, la réduction de leur coût numérique, et des applications industrielles possible