Search

The search for light sources with targeted characteristics motivates the work of a large part of the photonics community. One topical subject in this area is the study of Random Lasers (RLs), which use as feedback mechanism the light scattering in a random medium instead of a Fabry-Perot cavity [1]. A large variety of RLs and a diversity of applications have already been demonstrated, as reviewed in [1]. Of interest in many applications are RLs based on flexible hosts-which act not only as mechanical support-but also as scattering agent. Such host can be obtained, for example, by electrospinning fibers made by environment-friendly materials [3].

Fractal growth of polypyrrole results in the production of organic material matrix with improved surface area and electrical properties. The interaction of different surfactants and progressive polymerization of monomers of pyrrole during electrochemical process improve fractal growth mechanisms and contribute with development of material with superior response. In addition to high level of conductivity, high surface area and low cost of production, resulting polymeric matrix presents a strong action as bactericidal agent against Staphylococcus aureus and Klebsiella pneumoniae.

Nanocomposites of conducting polymers /metal nanoparticles (NC) have been considered important candidates for different applications involving determination and quantification of DNA due to their novel properties, viz. electronic, mechanical and optical response. The interaction of components with DNA is a critical step in the optimization of diagnostic applications. In this work, we have studied mechanisms of interaction of polyaniline - gold nanoparticle (PANI-Au) with DNA molecules by optical and electrical impedance spectroscopy. In both responses (absorbance at 318 nm and emission at 440 nm) a similar behavior with variation in the corresponding [P]DNA/[N]PANI-Au ratio is established, in agreement with EIS data, in a strong indication that EIS can be explored as an alternative technique for description of PANI-Au / DNA interactions.

The efficiency in the electricity generation provided by microbial fuel cells represents an important aspect to be improved in the development of new devices. In this work, we have explored a simple and low cost microbial fuel cell activated by Escherichia coli, which is immersed in nutrients (tryptic soy broth) with electron transfer mediated by methylene blue. Dual chamber reactor has compartments connected using different cation exchange membranes (Nafion and poly (methyl metacrylate)). The kinetics of energy generation was characterized by measurement of voltage between electrodes and power output as a function of concentration of mediator and type of cation exchange membrane.