Metallic plate corrosion and uptake of corrosion products by nafion in polymer electrolyte membrane fuel cells.

Nafion contamination by ferrous-alloy corrosion products, resulting in dramatic drops of the Ohmic potential, is a suspected major failure mode of polymer electrolyte membrane fuel cells that make use of metallic bipolar plates. This study demonstrates the potential of scanning transmission X-ray microscopy combined with X-ray absorption and fluorescence microspectroscopy for exploring corrosion processes of Ni and Fe electrodes in contact with a hydrated Nafion film in a thin-layer cell. The imaged morphology changes of the Ni and Fe electrodes and surrounding Nafion film that result from relevant electrochemical processes are correlated to the spatial distribution, local concentration, and chemical state of Fe and Ni species.

Morphological spatial patterns in a reaction diffusion model for metal growth.

In this paper a reaction-diffusion system modelling metal growth processes is considered, to investigate - within the electrodeposition context- the formation of morphological patterns in a finite two-dimensional spatial domain. Nonlinear dynamics of the system is studied from both the analytical and numerical points of view. Phase-space analysis is provided and initiation of spatial patterns induced by diffusion is shown to occur in a suitable region of the parameter space.

The relevance of nonlinear stacking interactions in simple models of double-stranded DNA.

Single molecule DNA experiments provide interesting data that allow a better understanding of the mechanical interactions between the strands and the nucleotides of this molecule. In some sense, these experiments complement the classical ones about DNA thermal denaturation. It is well known that the original Peyrard-Bishop (PB) model by means of a harmonic stacking potential and a nonlinear substrate potential has been able to predict the existence of a critical temperature of full denaturation of the molecule.