RESUMO
This study assessed the treatment of domestic wastewater to find the optimum vertical flow-constructed wetland (VFCW) configuration under tropical conditions. Eight pilot-scale configurations units were studied to compare between fine sand and medium gravel used as substrate, two feeding frequencies (20â pulses d-1 and 10â pulses d-1), and the presence or absence of tropical plants (Heliconia psittacorum). The results showed that the sand beds were significantly more efficient in the removal of organic matter, ammonia nitrogen, and total suspended solids than gravel beds, presenting average removal rates of 48 and 24â gâ m-2â d-1 of COD; 35 and 16â gâ m-2â d-1 of BOD5; 7 and 4â gâ m-2â d-1 of [Formula: see text]; 9 and 0â gâ m-2â d-1 for sand and gravel, respectively. The oxygen consumption rates were calculated and a value of 65â gâ m-2â d-1 was obtained for sand beds while for the gravel beds the consumption rate was 30â gâ m-2â d-1. The assessment of different kinds of nitrogen showed interesting dynamics in the nitrification processes. The presence of H. psittacorum showed positive effects in the total nitrogen (TN) removal. The different loading frequencies applied did not show significant statistical differences in the removal of the tested contaminants. Preliminary results were found in the pathogen removal, where the sand is favorable as the substrate. This work represents the first step in the research of optimum VFWC design and operation parameters for Colombia as well as the use of plants of the genus Heliconia.
Assuntos
Heliconiaceae , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Amônia/análise , Compostos de Amônio/análise , Análise da Demanda Biológica de Oxigênio , Colômbia , Desnitrificação , Enterobacteriaceae/isolamento & purificação , Nitrificação , Clima Tropical , Águas Residuárias/análise , Poluentes da Água/análiseRESUMO
The Helicobacter pylori CagA protein was the first bacterial oncoprotein to be identified as important in the development of human malignancies such as gastric cancer. It is not clear how it is able to deregulate a set of cell control mechanisms to induce carcinogenesis following translocation into human gastric epithelial cells. It is likely, however, that structural variations in the CagA sequence alter its affinity with the host proteins inducing differences in the pathogenicity of different H. pylori strains. Using the recently elucidated N-terminal 3D structure of H. pylori CagA, information on the full cagA gene sequence, and intrinsically disordered protein structure predictions methods we evaluated the interaction of different CagA variants with the kinase Src. An automated docking followed by molecular dynamics simulations were performed to explore CagA interaction modes with Src, one of its cellular partners. The computational approach let us establish that even in the presence of the same number and type of EPIYA motifs, CagA protein can reveal different spatial distributions. Based on the lowest affinity energy and higher number of interactions it was established that the principal forces governing the CagA-Src interaction are electrostatic. Results showed that EPIYA-D models presents higher affinity with some host proteins than EPIYA-C. Thus, we highlight the importance and advantage of the use of computational tools in combining chemical and biological data with bioinformatics for modeling and prediction purposes in some cases where experimental techniques present limitations.