1,317 research outputs found

    Complex Pt/Al2O3 materials for small catalytic systems

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    This paper reports on the preparation of catalytic materials composed of a porous metallic preform containing winding microchannels whose surface is coated by a complex catalytic film. Al2O3 is deposited inside the pores by means of wet impregnation in a first step, in order to increase the surface and to serve as an intermediate layer on which Pt nanoparticles are deposited in a second step. The latter deposition takes place by means of forced metalorganic chemical vapour infiltration (F-MOCVI). Pt(acac)2, is used in appropriate low pressure operating conditions, to allow for a process with low thermal budget, compatible with the geometrical and physical characteristics of the porous substrate. The results are evaluated by means of BET, SIMS, SEM/EDX and FEG/SEM. The catalytic material is finally being tested following the oxidation of carbon monoxide, a model reaction with high industrial interest

    Transition de l’enseignement primaire spécialisé vers l’enseignement ordinaire au cycle d’orientation: analyse du vécu de 5 jeunes ayant effectué cette transition

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    Le thème de ce travail de bachelor est celui de la transition entre l’école primaire et le cycle d’orientation des élèves issus de l’enseignement spécialisé. Le but principal de ce travail est donc de comprendre de quelle manière ces élèves parviennent ou ne parviennent pas à s’adapter à leur nouvel envir;nnement sc;laire. Ce travail permettra également de voir si ces élèves s’intègrent ou ne s’intègrent pas au sein de leur nouvelle école. Du point de vue théorique, cette transition est décrite comme une rupture qui oblige les élèves à vivre une transition, un changement nécessaire pour reconstruire un nouvel équilibre

    Image-guided multipolar radiofrequency ablation of liver tumours: initial clinical results

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    The local effectiveness and clinical usefulness of multipolar radiofrequency (RF) ablation of liver tumours was evaluated. Sixty-eight image-guided RF sessions were performed using a multipolar device with bipolar electrodes in 53 patients. There were 45 hepatocellular carcinomas (HCC) and 42 metastases with a diameter ≤3cm (n = 55), 3.1-5cm (n = 29) and >5cm (n = 3); 26 nodules were within 5mm from large vessels. Local effectiveness and complications were evaluated after RF procedures. Mean follow-up was 17 ± 10months. Recurrence and survival rates were analysed by the Kaplan-Meier method. The primary and secondary technical effectiveness rate was 82% and 95%, respectively. The major and minor complication rate was 2.9%, respectively. The local tumour progression at 1- and 2-years was 5% and 9% for HCC nodules and 17% and 31% for metastases, respectively; four of 26 nodules (15%) close to vessels showed local progression. The survival at 1year and 2years was 97% and 90% for HCC and 84% and 68% for metastases, respectively. Multipolar RF technique creates ablation zones of adequate size and tailored shape and is effective to treat most liver tumours, including those close to major hepatic vessel

    Manual wheelchair's turning resistance: swivelling resistance parameters of front and rear wheels on different surfaces

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    Purpose: Daily locomotion with a manual wheelchair includes curvilinear movements. However, little is known about the resisting forces in play during turning manoeuvres where the wheels are generally both rolling and swivelling. This study aimed at quantifying the swivelling resistance parameters of several wheels on different surfaces and to evaluate the effect of the curvature radius on these parameters. Materials and methods: A specific test bench was designed allowing the swivelling resistance parameters of a wheel rolling while swivelling to be determined. Seven wheels (3 front and 4 rear wheels), three surfaces (plywood, linoleum and carpet), two loads (25 and 45 kg) and five curvature radii (from 0 to 0.4 m) were tested through a full factorial design experiment. Results: Results showed that the wheel type was the most influential factor on swivelling resistance parameters, followed by the surface and the curvature radius. The effect of the load on swivelling resistance parameters was found negligible when compared to the influence of other factors. A predictive model for swivelling resistance parameters of the different wheel/surface combinations was proposed, as a function of the curvature radius. Conclusion: This study allowed the swivelling resistance parameters of different wheel/surface combinations to be quantified, as a function of the curvature radius of the wheel trajectory. Combined with data on rolling resistance, these data could now be used to assess energy losses during real life ambulation or to achieve more realistic behaviour in virtual rehabilitation environment. Implications for rehabilitation Swivelling resistances are increased by carpet surfaces compared to tile surfaces. Conversely to rolling resistance, castors wheels are less prone to swivelling resistance than rear wheels The swivelling resistance of a wheel rolling while swivelling is decreased compared to a pure swivelling movement. Combined with data on rolling resistance, these data on swivelling resistance would allow energy loss during daily life activity to be determined or as input data for the control of wheelchair simulator in virtual environment used for rehabilitation

    Phenotypes induced by NM causing α-skeletal muscle actin mutants in fibroblasts, Sol 8 myoblasts and myotubes

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    <p>Abstract</p> <p>Background</p> <p>Nemaline myopathy is a neuromuscular disorder characterized by the presence of nemaline bodies in patient muscles. 20% of the cases are associated with α-skeletal muscle actin mutations. We previously showed that actin mutations can cause four different biochemical phenotypes and that expression of NM associated actin mutants in fibroblasts, myoblasts and myotubes induces a range of cellular defects.</p> <p>Findings</p> <p>We conducted the same biochemical experiments for twelve new actin mutants associated with nemaline myopathy. We observed folding and polymerization defects. Immunostainings of these and eight other mutants in transfected cells revealed typical cellular defects such as nemaline rods or aggregates, decreased incorporation in F-actin structures, membrane blebbing, the formation of thickened actin fibres and cell membrane blebbing in myotubes.</p> <p>Conclusion</p> <p>Our results confirm that NM associated α-actin mutations induce a range of defects at the biochemical level as well as in cultured fibroblasts and muscle cells.</p

    Assessment of power losses due to ground contact forces during usual manual wheelchair movements

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    The aim of this study was to quantify the energy lost during typical daily living activities with a manual wheelchair.‘Fondation du sport français - Henri Sérandour

    Miniature probe for the delivery and monitoring of a photopolymerizable material

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    Photopolymerization is a common method to cure materials initially in a liquid state, such as dental implants or bone or tissue fillers. Recent advances in the development of biocompatible gel- and cement-systems open up an avenue for in situ photopolymerization. For minimally invasive surgery, such procedures require miniaturized surgical endoscopic probes to activate and control photopolymerization in situ. We present a miniaturized light probe in which a photoactive material can be (1) mixed, pressurized, and injected, (2) photopolymerized/photoactivated, and (3) monitored during the chemical reaction. The device is used to implant and cure poly(ethylene glycol) dimethacrylate-hydrogel-precursor in situ with ultraviolet A (UVA) light (365 nm) while the polymerization reaction is monitored in real time by collecting the fluorescence and Raman signals generated by the 532 nm excitation light source. Hydrogels could be delivered, photopolymerized, and monitored by the probe up to a curing depth of 4 cm. The size of the photopolymerized samples could be correlated to the fluorescent signal collected by the probe, and the reproducibility of the procedure could be demonstrated. The position of the probe tip inside a bovine caudal intervertebral disc could be estimated in vitro based on the collected fluores- cence and Raman signal

    Improved estimation of the left ventricular ejection fraction using a combination of independent automated segmentation results in cardiovascular magnetic resonance imaging

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    —This work aimed at combining different segmenta-tion approaches to produce a robust and accurate segmentation result. Three to five segmentation results of the left ventricle were combined using the STAPLE algorithm and the reliability of the resulting segmentation was evaluated in comparison with the result of each individual segmentation method. This comparison was performed using a supervised approach based on a reference method. Then, we used an unsupervised statistical evaluation, the extended Regression Without Truth (eRWT) that ranks different methods according to their accuracy in estimating a specific biomarker in a population. The segmentation accuracy was evaluated by focusing on the left ventricular ejection fraction (LVEF) estimate resulting from the LV contour delineation using a public cardiac cine MRI database. Eight different segmentation methods, including three expert delineations, were studied, and sixteen combinations of the five automated methods were investigated. The supervised and unsupervised evaluations demonstrated that in most cases, STAPLE results provided better estimates of the LVEF than individual automated segmentation methods. In addition, LVEF obtained with STAPLE were within inter-expert variability. Overall, combining different automated segmentation methods improved the reliability of the segmenta-tion result compared to that obtained using an individual metho
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