Levantamento quantitativo de microrganismos solubilizadores de fosfatos na rizosfera de gramíneas e leguminosas forrageiras na Amazônia

After choosing a selective enrichment medium suitable for most phosphate solubilizing microorganisms, a quantitative survey of these was made in the rhizosphere of: Brachiaria decumbens, B. humidicola. Andropogon gayanus, Paspalum plicatum, Hyparrhenia rufa, Panicum maximum, Desmodium ovalifolium, Pueraria phaseoloides, Zornia sp., Stylosanthes capitata, S. guianensis (CIAT 136). and S. guianensis (IKE 1022, with and without fertilisers. The largest numbers of phosphate solubilizing bacteria (above 1 x 107/g rhizosphere) occurred in the rhizosphere of the leguminous species a nd small numbers (Belw 1 x 107/g rhizosphere) in grasses without fertilisers, except H. rufa and P. maximum. From all the fodder plants analysed, Zornia sp. (Leguminosae) with fertilizer, had the greatest number as phosphate solubilizers. The total number of microorganisms was greater in the treatments without fertilizer in all grasses analysed; but for the leguminous species it was greater for treatments with fertilizer except in S. capitata. Phosphore solubilizing fungi were not considered in this study because they present only in small numbers.Após a escolha de um meio de enriquecimento seletivo a um maior número de microrganismos solubilizadores de fosfatos, foi feito um levantamento quantitativo dessas bactérias na rizosfera de Brachiaria decumbens, B. humidicola; Andropogon gayanus, Paspalum plicatum, Hyparrhenia rufa, Panicum maximum, Desmodium ovalifolium, Pueraria phaseoloides, Zornia sp. Stylosanthes capitata, S. guianensis (ClAT 136) e S. guianensis (IRI 1022), adubadas e não adubadas. De um modo geral, números maiores de bactérias solubilizadoras de fosfatos (superior a 1 x 107/g rizosfera) ocorreram na rizosfera de leguminosas. adubadas e não adubadas, e os números mais baixos nas gramíneas (inferior a 1 x 107/g rizosfera). com exceção de H. rufa e P. maximum, sem adubação. De todas as forrageiras analisadas, a rizosfera de Zornia sp. adubada, foi a que melhor se apresentou tanto em número quanto em porcentagem de bactérias solubilizadoras. O número total de microrganismos foi maior nos tratamentos não adubados para todas as gramíneas analisadas e maior nos tratamentos adubados para todas as leguminosas com exceção de S. capitata. Os fungos solubilizadores de fosfatos, não foram considerados, uma vez que estavam presentes em quantidades bem pequenas

High Efficiency Thermoacoustic Loudspeaker Made with a Silica Aerogel Substrate

The extremely low thermal effusivity of the silica aerogel is exploited to develop a high efficiency thermoacoustic (TA) loudspeaker with solid substrate. The deposition of the electrically conductive, low heat capacity active film on the silica aerogel surface is achieved with both the spray coating of silver nanowires and the sputter coating of gold films. The uniform spray coating of the hydrophobic silica aerogel is enabled by a low pressure plasma treatment, which however impairs its robustness. The spray-coated samples prove to be fragile when subjected to elevated temperatures and thus not suitable for TA applications. Sputter coating, not requiring any treatment of the aerogel surface, allows the fabrication of working TA loudspeaker samples with a 100 nm gold active film. The electroacoustic response of the gold-sputtered silica aerogel TA loudspeaker is characterized at different input power levels. The experimental results are compared with those present in literature, showing an improved efficiency with respect to the other TA loudspeakers with solid substrate