The use of microsensors to study the role of the loading rate and surface velocity on the growth and the composition of nitrifying biofilms

The good composition and activity of biofilms are very important for successful operation and control of fixed-film biological reactors employed in liquid effluents treatment. During the last decade, microsensors have been applied to study microbial ecology. These sensors could provide information regarding the microbial activity concerning nitrification and denitrification that occur inside biofilms. Other techniques of molecular biology, such as fluorescence in situ hybridization (FISH), have also contributed to this matter because their application aids in the identification of the bacterial populations that compose the biofilms. The focus of this paper was to study the loading rate and surface velocity to promote the development of nitrifying biofilms in three distinct flow cells that were employed in the post treatment of a synthetic wastewater simulating the effluent from a UASB (Upflow Anaerobic Sludge Blanket) reactor. Using the FISH technique, it was found that the population of ammonia-oxidizing-bacteria was greater than that of nitrite-oxidizing-bacteria; this was also supported by the lower production of nitrate determined by physicochemical and microsensor analyses. It was verified that the loading rate and surface velocity that promoted the greatest nitrogen removal were 0.25 g N-amon m(-2)biofilm day(-1) and 1 m h(-1), respectively.

Elderly Mexican women's perceptions of exercise and conflicting role responsibilities

The purpose of this pilot study was to explore elderly Mexican women's readiness to exercise, and their multiple roles. Fifty older women were sampled from two separate neighborhoods of low socio-economic status. Readiness to exercise was examined using the Stages of Change - Exercise instrument with six categories: precontemplation nonbelievers, precontemplation believers, contemplation, preparation, action, and maintenance. Time devoted to the following functional roles was explored: wife, household, grandmother, personal care, and recreational. Women fell mainly under the first three stages of change both, precontemplation nonbelievers and believers, and the contemplation stage. The stages of change scale and role commitments were not significantly related. Nevertheless, precontemplators devoted less time in all the roles than the women in the other categories of stage of change.