Porosity determination of ceramic materials by digital image analysis--a critical evaluation.

Measuring the porosity of materials by digital image analysis of micrographs is a well-established and convenient method for the testing of metallic samples. However, when applied to ceramic materials, this method has been shown to be much less reliable and poorly reproducible. The purpose of this present work is to clarify the reason for this deficiency, involving many porosity measurements, performed on plasma-sprayed zirconia, under systematically varied microscopic imaging conditions, and the porosities being calculated using various evaluation methods.

PROPHIS: parabolic trough-facility for organic photochemical syntheses in sunlight.

The PROPHIS facility is an efficient tool for the synthesis of chemicals with moderately concentrated sunlight on a semi-technical scale. The feasibility of selected solar photochemical reaction classes--including heterogeneous and homogeneous reactions--has been demonstrated using various set-ups of the plant. This paper outlines the potential of solar photochemistry by representative examples.

Paper mill wastewater detoxification by solar photocatalysis.

In the WATER project the German Aerospace Center, and the Universidade Federal de Uberlândia, analyse the possibilities of treating paper mill effluents by solar photocatalysis for the paper mill of the Brazilian paper producer Votorantim Celulose e Papel, VCP, at Luiz Antônio, SP, Brazil. The degradation of the bio-polymer lignin is a vast problem in paper production. The tests have shown that treatment by the photocatalyst TiO2 and solar radiation is an ecological future oriented approach to solve this problem.