Formation of periodic patterns during coalescence of reactive sessile droplets

International audienc

On precipitation during the coalescence of reactive droplets

International audienc

Structured solvent effects on precipitation

The synthesis of cerium oxalate, a reaction intermediate in the preparation of high performance ceramics, is studied in sessile droplets. We compare here the effect of alcoholic solvents with the usage of structured solvents, namely ultra-flexible microemulsions in the water-rich and oil-rich configurations. The nucleation and the growth of cerium oxalate particles are the result of local mixing by the Marangoni flow of droplets loaded with oxalic acid and cerium nitrate. The morphology of the particles is very different depending on the composition of the solvent and on the mixing process. We show that the variation of the particle morphology results from the difference of the structured solvent microphases during the precipitation process. When the precipitation occurs in a water continuous phase, usual needle-like oxalate particles precipitate. When the precipitate is formed in the dispersed phase of the emulsion, structured aggregates, as close-packed aggregates of needles, are compacted by microcapillarity effects

Pediatr Blood Cancer

BACKGROUND: In order to evaluate at the population level the impact of the actions developed in France since 2004 to organize the care of adolescents and young adults (AYAs) with cancer, we conducted the present study to provide an unbiased view of the pathway of care of these patients. METHODS: Using a population-based registry, we conducted a review of all cases of cancer diagnosed during 2012 and 2013 in 15- to 24-year-old patients living in nineteen French administrative areas. RESULTS: The median times for diagnosis and treatment of the 993 included AYAs were 9 weeks (3-22) and 1 day (0-20), respectively. Delays in diagnosis were significantly longer in young adults than in adolescents, especially for soft-tissue sarcomas (48.7 weeks vs. 15.4 weeks, P = 0.04) and bone tumors (21.4 weeks vs. 10.1 weeks, P = 0.04). The first physicians seen by patients were mostly general practitioners (67.4%). Most patients (77.5%) were treated in adult units. Management decisions were taken within the context of a multidisciplinary team (MDT) in 85.3% of cases. MDT meetings that involved both pediatric and adult oncologists were uncommon (15.7% of patients). Twenty-six percent of patients were included in randomized or nonrandomized clinical studies. The proportion of inclusion was significantly higher in adolescents (39.5%) than in young adults (16.8%). CONCLUSION: In France, pathways of care for AYAs are heterogeneous. It is necessary to organize a national network of expert centers with adequate medical skills and specific psychosocial support and facilities to provide the best possible care for these patients

Physicochemical hydrodynamics of droplets out of equilibrium

Droplets abound in nature and technology. In general, they are multicomponent, and, when out of equilibrium, have gradients in concentration, implying flow and mass transport. Moreover, phase transitions can occur, in the form of evaporation, solidification, dissolution or nucleation of a new phase. The droplets and their surrounding liquid can be binary, ternary or contain even more components, with several in different phases. Since the early 2000s, rapid advances in experimental and numerical fluid dynamical techniques have enabled major progress in our understanding of the physicochemical hydrodynamics of such droplets, further narrowing the gap from fluid dynamics to chemical engineering and colloid and interfacial science, arriving at a quantitative understanding of multicomponent and multiphase droplet systems far from equilibrium, and aiming towards a one-to-one comparison between experiments and theory or numerics. This Perspective discusses examples of the physicochemical hydrodynamics of droplet systems far from equilibrium and the relevance of such systems for applications