The steady state hole transport properties of GaSb were investigated by the Ensemble Monte Carlo method (EMC). In our model we taken in to account heavy and light hole valence bands, and the following scattering mechanisms: inelastic acoustic phonon; polar optical phonon; nonpolar optical; ionized impurity. The theoretical calculations are compared with available experimental results for the GaSb hole mobility shown good agreement with temperatures from 90K up to 300K.

The main focus of this thesis is the IR spectral regime, which since the 70's and 80's has revolucionised our understanding of the Universe. A multi-wavelength analysis on Extremely Red Galaxy populations is rst presented in one of the most intensively observed patch of the sky, the Chandra Deep Field South. By adopting a purely statistical methodology, we consider all the photometric and spectroscopic information available on large samples of Extremely Red Objects (EROs, 553 sources), IRAC EROs (IEROs, 259 sources), and Distant Red Galaxies (DRGs, 289 sources). We derive general properties: redshift distributions, AGN host fraction, star-formation rate densities, dust content, morphology, mass funtions and mass densities. The results point to the fact that EROs, IEROs, and DRGs all belong to the same population, yet seen at di erent phases of galaxy evolution. The second part of this thesis is dedicated to the AGN selection in the IR, with particular relevance to the soon to be launched James Webb Space Telescope in 2014. We develop an improved IR criterion (using K and IRAC bands) as an alternative to existing IR AGN criteria for the z . 2:5 regime, and develop another IR criterion which reliably selects AGN hosts at 0 < z < 7 (using K, Spitzer-IRAC, and Spitzer-MIPS24 m bands, KIM). The ability to track AGN activity since the end of reionization holds great advantages for the study of galaxy evolution. The last chapter of this thesis focus on the importance of dust. Based on deep IR data on the Cosmological Survey, we derive rest-frame 1.6, 3.3, and 6.2 m luminosity functions and their dependency on redshift. We estimate the dust contribution to those wavelengths and show that the hot dust luminosity density evolves since z = 12 with a much steeper drop than the star-formation history of the Universe.

Toxicity tests with aquatic organisms constitute an effective tool in the evaluation, prediction and detection of the potential effect of pollutants from environmental samples in living organisms. Vinasse, a highly colored effluent, is a sub-product rich in nutrients, mainly organic matter, with high pollutant potential when disposed in the environment. Assays for vinasse decolorization were performed using the fungus Pleurotus sajor-caju CCB020 in vinasse biodegradation study, were occurred reductions of 82.8% in COD, 75.3% in BOD, 99.2% in the coloration and 99.7% in turbidity. The vinasse toxicity reduction was determined by the exposition to the following organisms: Pseudokirchneriella subcapitata, Daphnia magna, Daphnia similis and Hydra attenuata. This work concluded that the systematic combination of P. sajor-caju and vinasse can be applied in the bioprocess of color reduction and degradation of complex vinasse compounds, with reduction in the toxicity and improving its physical–chemical properties.

Physicochemical and ecotoxicological measurements were employed to appraise the water quality of the Corumbataí River raw water (RW) intake, and that of its filtered (FW) and treated (TW) waters, processed by the Water Treatment Plant (WTP) of Piracicaba (SP,Brazil) during 2010. Some herbicides: ametrine, atrazine, simazine and tebuthiuron, were measured, with levels ranging from 0.01 to 10.3 µg L-1. These were lower than those required to produce ecotoxicological effects to aquatic life based on published literature. Similarly, trihalomethanes, such as chloroform and bromodichloromethane produced as a result of the WTP process were also shown to be present in concentrations that would neither harm environmental nor human health. Elevated free chlorine concentrations found in FW and TW were credibly responsible for toxicity effects observed in algae and daphnids. (Pseudokirchneriella subcapitata and Daphnia magna). In contrast, results of toxicity testing conducted with Hydra attenuata suggested that this organism is resistant to free chorine and could be used for drinking water evaluations. Coupling bioassays with chemical analyses proved valuable to uncover putative cause-effect relationships existing between physical, chemical and toxic results, as well as in optimizing data interpretation of water quality.