Papers by Author: E. Reyes-Melo

Abstract: In this work, iron oxide nanoparticles (~5 nm) embedded in a chitosan polymer film, were synthesized. In order to obtain this nanostructured material, firstly a homogenous film of Fe(II)-chitosan was prepared. The resulting composite film has a thickness of ~140μm. Iron oxide nanoparticles were in-situ synthesized by treating the composite film with H2O2 under alkaline conditions. The morphological analysis by Transmission Electron Microscopy (TEM) shows the nanoparticles were embedded and stabilized in chitosan polymer film. The magnetic behavior was studied by magnetization measurements. The magnetization curves at room temperature showed that iron oxide nanoparticles have a superparamagnetic behavior.

Abstract: In the present work we discuss the self-affine properties of the fracture surfaces of sodalime glass obtained under quasi-static conditions. The fracture surfaces are generated using a threepoint bending system in normal room conditions and under high humidity conditions. The surfaces were recorded both by Scanning Electron Microscopy and Atomic Force Microscopy, and their selfaffine properties are characterized using the Variable Bandwidth method. For both conditions it is observed that the major part of the fracture surface is occupied by the mirror zone. On the other hand, the self-affine analysis reveals that for both conditions the roughness exponent has values centred at around 0.58 with moderate dispersion, in agreement with previous results. Our findings support the hypothesis of the existence of a characteristic roughness exponent for quasi-static fracture with a value that is significantly lower than the value of 0.8 reported for rapid fracture conditions.