SynopsisProtection against ultraviolet (UV) radiation is the major function of sunscreen lotions and UV-protective coatings for vehicles, homes, equipment and clothing. Sunscreen formulations have been optimized to become protective over a broader spectrum of UV radiation and maintain greater photostability. They are comprised of organic and inorganic components that act as chemical and physical UV protectors, respectively. Some of the organic components are limited by their spectrum of protection and photostability. Studies using solid lipid nanoparticles, recently explored organic molecules, inorganic components and antioxidants attempt to further optimize UV protection. In this review, we examine traditional and emerging nanoparticle components and highlight novel ideas in UV protection which may provide pathways for future studies. Ré suméLa protection contre les rayons ultraviolets (UV) est la principale fonction des crèmes solaires et des revêtements de protection UV pour les véhicules, les logements, les équipements et les vêtements. Les formulations solaires ont été optimisées pour devenir des protections de large spectre UV et pour maintenir une plus grande photo stabilité. Ils sont composés de matières organiques et inorganiques qui agissent comme des produits de protection respectivement chimique et physique contre les UV. Certains des composants organiques sont limités par leur spectre de protection et leur photo stabilité. Les études récentes de nanoparticules lipidiques solides (SLN) des molécules organiques, inorganiques et antioxydants, ont exploré des voies d'optimisation de protection UV. Dans cette revue, nous examinons les composants traditionnels et les nanoparticules émergentes ainsi que les idées de protection UV pour proposer de futures études.

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Flows of concentrated suspensions at low Reynolds number through an asymmetric T-junction bifurcation composed of rectangular channels are studied experimentally using nuclear magnetic resonance imaging. In contrast to the unequal division of a uniform concentration material, the suspension and the neutrally buoyant, noncolloidal particles are almost equally partitioned between downstream branches, and motion of particles across the dividing stream surface is deduced to occur at the bifurcation. We attribute the rearrangement of particles to enhanced spreading of high concentration ͑and therefore high local viscosity͒ regions of the suspension toward the side branch. The partitioning is accompanied by lateral asymmetry in the concentration and velocity profiles of the downstream branches, although the inlet profiles are symmetric. In the spanwise direction, inhomogeneous concentration distributions that develop upstream persist throughout the inlet and downstream channels. Overall, the fractions of the flow rate and cross-sectional area flowing into the side branch vary slightly with bulk particle volume fraction. Also, inertial effects likely cause an observed shift of the dividing streamline toward the side branch as the flow rate increases, while the flow rate and particle flux fractions entering the side branch hardly change. Finally, directional asymmetry is observed between diverging and converging flows.

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