Metal-oxide solid solutions for light alkane sensing

Sensing of light alkanes via chemoresistive gas sensors has been addressed. Screen-printed films of a solid solution of mixed Sn and Ti oxides have been selected for the purpose. We demonstrate that the films sensitively detect 100ppm of such gases and 500ppm of methane, two levels which are by far lower than the alarm limits for these gases. Information about the working mechanism of chemical reactions at surface has been discussed under either dry or wet condition

Metal-oxide solid solutions for light alkane sensing

Sensing of light alkanes via chemoresistive gas sensors has been addressed. Screen-printed films of a solid solution of mixed Sn and Ti oxides have been selected for the purpose. We demonstrate that the films sensitively detect 100ppm of such gases and 500ppm of methane, the two levels being by far lower than the alarm limits for these gases. Information about the working mechanism of chemical reactions on the surface has been discussed under either dry or wet condition

Role of the synthesis of nanopowders in the gas sensing behavior of metal oxides

The atmospheric pollutant monitoring is a present need that pushes the development of reliable and cheap solid-state gas sensors. Very small concentrations of pollutants are able to dramatically deteriorate air quality, thus atmospheric monitoring methods should be able to evaluate very low gas concentration levels. Aim of this work is to compare the sensing performances of metal-oxides powders obtained by means of sol-gel (SG) and hydrothermal (HY) method. TiO2 and SnO2 are two of the most common materials able to sense gases upon variations of their energy barrier. One of the main factors enhancing the detection properties of these oxides is the grains dimension. Sharp increase in sensitivity is in fact expected when the grain size becomes smaller than the space charge width. The work is focused on the different methodology and on the outcome related to the two methods. The properties of TiO2 and SnO2 are investigated either as powders or as thick layers, the latter necessary to prepare thick film gas sensors. © 2007 Materials Research Society

The Use Of Intestinal Enema In Labor Preparation: Analysis Of Advantages And Disadvantages [o Uso Do Enteroclisma No Preparo Para O Parto: Análise De Suas Vantagens E Desvantagens.]

This study aimed at investigating the effects of intestinal cleansers on fecal contamination during labor and delivery amongst women assisted in a university hospital. The subjects were 90 pregnant women (43 normal births, 27 forceps and 20 caesarean sections). The population was divided in two randomized groups: with and without the use of intestinal cleansers. It was possible to conclude that intestinal cleansers did not provide faster labor and did not reduce fecal contamination. However, the women who had used an intestinal cleanser tended to regard it as positive.96495