65 research outputs found

    Aging mechanism in tunable Pickering emulsion

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    We study the stability of a model Pickering emulsion system. A special counter-flow microfluidics set-up was used to prepare monodisperse Pickering emulsions, with oil droplets in water. The wettability of the monodisperse silica nanoparticles (NPs) could be tuned by surface grafting and the surface coverage of the droplets was controlled using the microfluidics setup. A surface coverage as low as 23%\% is enough to stabilize the emulsions and we evidence a new regime of Pickering emulsion stability where the surface coverage of emulsion droplets of constant size increases in time, in coexistence with a large amount of dispersed phase. Our results demonstrate that the previously observed limited coalescence regime where surface coverage tends to control the average size of the final droplets must be put in a broader perspective

    Assessment of team training in management of adverse acute events occurring during cardiopulmonary bypass procedure: a pilot study based on an animal simulation model (Fouilloux, Team training in cardiac surgery)

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    Successful cardiac surgery is highly dependent upon effective and efficient teamwork. Practical training and development will further enhance the team ability to react to a series of low-frequency occurring adverse events during cardiopulmonary bypass (CPB). One of our specialized educational programs focuses on training the whole team. This training is based on an original animal simulation model. The objective of this pilot study was to assess our method of training and learning in an attempt to optimize and improve team management and functioning. Methods: Four members of the same cardiac surgery team joined our program. They performed a common procedure, with a cardiopulmonary bypass (CPB) circuit set up to produce several adverse incidents. Events management was ana¬lyzed and debriefed in technical and non-technical perspectives. Results: Management of the adverse events was significantly improved. Discussion and debriefing time was fundamental in identifying the most appropriate management for each event. Rescue procedures were assimilated and team training was found to be effective, with the time reduced by up to 50% for 3 events and by up to 70% for air embolism. Conclusion: Our pilot program is an innovative, low-cost tool for the improvement of the management of adverse events occurring during CPB. It includes the different components of surgical education and training. Such an educational tool might be relevant for training. To confirm those encouraging results, it should be assessed in a larger surgical team panel. Further investigations are required for assessing efficiency in real conditions

    Evaporation of an emulsion trapped in a yield stress fluid

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    The present work deals with emulsions of volatile alkanes in an aqueous clay suspension, Laponite, which forms a yield stress fluid. For a large enough yield stress (i.e. Laponite concentration), the oil droplets are prevented from creaming and the emulsions are thus mechanically stabilized. We have studied the evaporation kinetics of the oil phase of those emulsions in contact with the atmosphere. We show that the evaporation process is characterized by the formation of a sharp front separating the emulsion from a droplet-free Laponite phase, and that the displacement of the front vs. time follows a diffusion law. Experimental data are confronted to a diffusion-controlled model, in the case where the limiting step is the diffusion of the dissolved oil through the aqueous phase. The nature of the alkane, as well as its volume fraction in the emulsion, has been varied. Quantitative agreement with the model is achieved without any adjustable parameter and we describe the mechanism leading to the formation of a front

    Should transcatheter closure of atrial septal defects with inferior-posterior deficient rim still be attempted?

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    International audienceBackground: Transcatheter closure for atrial septal defect (ASD) with inferior-posterior rim deficiency hasbeen scarcely reported with proper identification of the indications and limits. We aimed to assess the safetyand feasibility of transcatheter closure of ASDs with deficient rims, paying particular attention to cases withinferior-posterior rim deficiency.Methods: From January 2008 to January 2013, 241 patients underwent transcatheter ASD closure,including 50 cases (20.7%) with deficient rims, other than the anterior-superior one. Eighteen patients(12 females) presented inferior-posterior rim deficiency. Their median age was 8 (1.4–85) years and theirmedian weight was 24 [9–97] kg. Transcatheter closure was performed in all cases under transesophageal echocardiography (TEE) guidance in children and intracardiac echocardiography (ICE) guidance in adults.Results: Out of 18 patients with inferior-posterior rim deficiency, only 8 underwent successful immediate transcatheter closure. Four cases failed to be closed. Major complications occurred in 6 patients, including 4 device embolizations, 1 pericardial effusion and 1 complete atrioventricular block that resolved after surgical removal of the device. During a median follow up of 54±13 months, a residual right-to-left shuntwas documented in 2 more cases, requiring surgery in one case because of cyanosis. Transcatheter closure was successfully performed in the rest of the 223 patients, including in the 32 cases with deficient rims other than inferior-posterior.Conclusions: Transcatheter closure of ASDs with inferior-posterior rim deficiency cannot b
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