Pyrolysis final temperature effects on biochar stability.

Pyrolysis technology can be used for producing biochar and bio-oil simultaneously, as an effective and sustainable mean to produce renewable bioenergy and a carbon rich soil amendment that can be used for carbon sequestration and agronomic benefits. However, pyrolysis products yields and biochar stability are strongly affected by the feedstock and pyrolysis variables, especially the final temperature. This study was carried out to evaluate the effect of pyrolysis final temperature on biochar stability after thermochemical oxidation. For this experiment, two species of hardwood and two species of softwood with particle size between 0.5 and 2.0 mm were pyrolized at five different final temperatures (350, 400, 450, 500 and 550°C) for 60 min at an muffle furnace with limited supply of O2. Thermochemical oxidation was performed for the solid products (biochar). As pyrolysis final temperature increased, biochar stability increased as well, indicating that these materials would be more resistant to degradation when applied into soil

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A interação entre os conhecimentos de um professor atuante e de um aspirante como subsídio para a aprendizagem da docência Knowledge exchange by an experienced teacher and an inexperienced one as an aid in learning how to teach

A presente pesquisa traz alguns resultados obtidos com base em um processo de parceria entre um professor com experiência profissional docente e um professor aspirante, tendo o pesquisador como mediador. Toma-se, como eixo para análise, a 'base de conhecimentos para o ensino' de Shulman (1987), e como contexto para coleta dos dados, a elaboração, implementação e análise de um conjunto de aulas de Ciências dedicadas às séries iniciais do Ensino Fundamental. Os resultados apontam que a justaposição de professores não garante a troca de todo e quaisquer tipos de conhecimentos, até mesmo porque, dependendo do momento profissional em que o docente se encontra, são diferentes suas necessidades e a forma como se interpreta e dá significado à sua prática.<br>This research presents results obtained from a partnership between a veteran teacher, a teacher-to-be and the researcher, who acted as the mediator. The 'knowledge base of teaching' by Lee Shulman was the reference for analysis and the context, within which data was collected, and included the elaboration, implementation and analyses of a series of Natural Sciences Classes for the lower grades of Elementary School. The results point out that putting teachers together does not ensure complete or even partial exchange of knowledge, because teachers´ needs and the way they interpret and focus on their professional practice depend on their professional momentum