Biogeomorphic succession in a fluvial-lacustrine delta of the Middle Paraná River (Argentina): Feedbacks between vegetation and morphodynamics.

The Leyes' Delta lies at the Middle Paraná River, the second-largest fluvial system in South America, and it is being quickly formed into the Setúbal fluvial lake, Argentina. In the context of the Fluvial Biogeomorphic Succession theory, our aim was to better understand interactions between physical and biotic processes contributing to the formation of the Leyes' Delta. We studied the genesis, morphologic development, and vegetation in three groups of its deltaic islands with contrasting formation ages.

Towards conductive textiles: coating polymeric fibres with graphene.

Conducting fibres are essential to the development of e-textiles. We demonstrate a method to make common insulating textile fibres conductive, by coating them with graphene. The resulting fibres display sheet resistance values as low as 600 Ωsq, demonstrating that the high conductivity of graphene is not lost when transferred to textile fibres.

Effects of fullerene addition on the thermo-optical properties of smectic liquid crystals at the vicinity of the nematic-smectic-A phase transition.

The present work is devoted to the study of the thermo-optical properties of liquid crystals doped with traces of fullerene C(60) at the vicinity of the nematic-smectic-A phase transition. By using the time-resolved Z-scan technique, we measure the temperature dependence of the thermo-optical coefficient and the thermal diffusivity. Our results reveal that the critical behavior of the thermal diffusivity is strongly affected by the fullerene addition.

Elastic mediated force between nanoparticles adsorbed on smectic films under an external field.

Within the harmonic approximation, we analytically determine the elastic-mediated interaction between colloidal nanoparticles adsorbed on the surface of smectic films under the influence of an external field. Both cases of free-standing films and films deposited over a solid substrate are considered. We show that the asymptotic decay (1/R in free-standing and exponential in deposited films) is not altered by the external field.

Crossover from tricritical to critical end point behavior in free-standing smectic films.

We study the smectic to nematic (SmA-N) phase transition taking place at the center of a free-standing film that exhibits enhanced surface order due to the anchoring promoted by a surrounding gas. The usual McMillan mean-field approach predicts that the SmA-N transition in bulk samples can be continuous or discontinuous (first or second order) depending on the molecular geometry, with a tricritical point separating these two regimes. Here we show that the additional orientational order imposed by the surface anchoring stabilizes the surface-induced smectic and nematic phases, leading to the breakdown of the tricritical point and to the emergence of a critical end point.

Field-induced layer thinning transition on free-standing smectic films.

Strongly anchored free-standing smectic films usually present a stepwise reduction of the number of layers when the temperature is raised above the smectic-isotropic bulk transition temperature. Here, we demonstrate that a field-induced layer thinning transition can take place in smectic films with a negative dielectric anisotropy even below the bulk transition temperature. Using an extended McMillan's model, we provide the phase diagram of this layering transition and show that, when the field is raised above the bulk transition field, the film thickness reduction is well described by a power law with an exponent that depends on the temperature and the aspect ratio of the liquid-crystal molecule.

[Signs, meanings, and actions associated with Chagas disease].

An anthropological approach was employed to investigate the universe of representations (ways of thinking) and behaviors (ways of acting) associated with Chagas disease in a group of public service workers in Belo Horizonte (both infected and not infected with Trypanosoma cruzi). An attempt was also made to evaluate the repercussions of this universe of representations and behaviors on the lives of the infected individuals. The collection and analysis of the data followed the "systems of signs, meanings, and actions" model developed by Corin et al.