The occurrence of benzene, toluene, ethylbenzene, and xylenes (BTEX) in some public areas of Curitiba-PR, Brazil, was evaluated. Their concentrations were then related to the vegetation's density in each area. Average benzene concentrations varied from 3.9 to 6.1 μg m-3, with higher values occurring in poorly dense vegetation areas. For toluene, average concentrations ranged from 6.5 to 7.2 μg m-3. The effect of such pollutants was evaluated by means of a bio indicator, Tillandsia stricta. Variation in total chlorophyll content and in stomatic density were detected in some samples and may be related to the BTEX concentrations found in the studied areas.

Pequenas partículas de fase peroviskita de BaMnO3 foram preparadas por dois métodos: a rota da coprecipitação convencional (RCC) e o método convencional de microemulsão (MCM). As técnicas instrumentais utilizadas para caracterizar as amostras foram: microscopia eletrônica de varredura (SEM), difratometria de raios X (XRD), termogravimetria (TG) e análise térmica diferencial (DTA). A síntese de materiais em sistemas coloidais auto-organizados tem por objetivo aumentar a homogeneidade de tamanho e forma das partículas. Nos últimos anos aumentou a busca por materiais mais uniformes visando o aperfeiçoamento da microestrutura. A rota de microemulsão é um método alternativo para a síntese de materiais porque permite o controle da relação entre as concentrações de água e do tensoativo, (w), o qual controla o tamanho das gotículas de microemulsão denominadas microreatores. Peroviskita pura obtida de microemulsão forma-se em temperatura menor do que a fase precipitada, e resulta.em partículas com distribuição de tamanho mais adequada, de aproximadamente 0,1 mm de diâmetro comparado com a média de 0,5 mm das partículas coprecipitadas.

The present work focuses on the synthesis of small particles of the perovskite phase of BaMnO3 through the route of conventional coprecipitation (RCC) and the method of conventional microemulsion (MCM). The techniques used for samples characterization were: scanning electron microscopy (SEM), X-ray diffraction patterns (XRD), thermogravimetry (TG) and differential thermal analysis (DTA). The synthesis of materials in self-organized colloidal system has as main objective to increase the shape and size homogeneity of the particles. In the last years it has been intensified the search for more homogeneous materials. The microemulsion route is an alternative method for the synthesis of more homogeneous material because it allows for controlling the relationship of water to surfactante concentrations, (w), which controls the average size of the microemulsion drops. Pure perovskite BaMnO3 phase obtained from microemulsion appears at smaller temperature than the precipitated one, and results in a better size distribution of the particles, around 0,1 mm in diameter compared to 0,5 mm obtained by coprecipitation.