Drying Mechanisms in Plasticized Latex Films: Role of Horizontal Drying Fronts.

This article presents studies on the drying kinetics of latexes with particles made progressively softer by adding increasing amounts of a plasticizer, in relation to speeds of horizontal drying fronts and particle deformation mechanisms. Global drying rates were measured by gravimetry, and speeds of the horizontal fronts were recorded using a video camera and image processing. Particle deformation mechanisms were inferred using the deformation map established by Routh and Russel (RR). This required precise measurements of the rheological properties of the polymers using a piezorheometer. The results show that latexes with softer particles dry slowly, but in our systems, this is not due to skin formation. A correlation between global drying rates and speeds of horizontal fronts could be established and interpreted in terms of the evolution of mass transfer coefficients of water in different areas of the drying system. The speeds of the horizontal drying fronts were compared with the RR model. A remarkable qualitative agreement of the curve shapes was observed; however, the fit could not be considered good. These results call for further research efforts in modeling and simulation.

[Fetomaternal hemorrhage: practitioner's point of view]. / Hémorragie foetomaternelle : le point de vue du clinicien.

Fetomaternal hemorrhage is known to have a wide spectrum of clinical presentations. This large variability probably explains why there are still neither consensual classification nor management recommendations. Nevertheless, fetomaternal hemorrhage is a serious condition, which may cause life-threatening fetal anemia. Fetal tolerance mainly depends on the quantity of fetal blood loss as well as the rate at which it occurs. Decrease in perceived fetal movements represents the main clinical sign of fetomaternal hemorrhage and justify use of diagnostic tests such as the Kleihauer-Betke test. Large fetomaternal hemorrhages can also induce fetal hydrops and stillbirth. In this review, we emphasize the clinical and biological features of fetomaternal hemorrhages and we highlight the circumstances associated with false-negative and false-positive results of the Kleihauer-Betke test. We also propose an original algorithm for the management of fetomaternal hemorrhages.