A murcha bacteriana, causada por Ralstonia solanacearum, é considerada uma doença de importância para a cultura da berinjela, sendo de difícil controle. O controle de doenças através de indução de resistência é um método que vêm se revelando como promissor. Basidiomas de Agaricus blazei e Lentinula edodes possuem substâncias do tipo antibiótico e outras substâncias capazes de atuarem como elicitoras da resposta de resistência em plantas, mostrando-se assim promissores no controle alternativo de fitopatógenos. O presente trabalho foi conduzido com o objetivo de estudar o efeito de extratos aquosos dos fungos e do indutor químico acibenzolar-S-metil (aSm) sobre o crescimento da bactéria in vitro e o controle da murcha bacteriana, bem como investigar seu efeito sobre a atividade de determinadas enzimas da planta. O efeito inibitório sobre o patógeno foi avaliado usando diferentes concentrações dos extratos aquosos. A indução de resistência foi estudada em plantas tratadas com o indutor biológico e químico, medindo-se a intensidade de murcha e determinando-se as alterações de algumas enzimas. Os resultados revelaram que os isolados de A. blazei e L. edodes, utilizados em diversas diluições, não exerceram efeito inibitório in vitro. Em relação à indução de resistência, extratos dos isolados Abl-11 e Abl-28 de A. blazei (15%, v/v) e o aSm (0,05 g/L) promoveram redução significativa na ocorrência de folhas murchas, quando aplicados dois dias antes da inoculação. O aumento na atividade de peroxidase foi verificado em plantas tratadas com extratos de Abl-11, Abl-28 e com suspensão de aSm. A atividade de quitinase, fenilalanina amônia-liase e polifenoloxidase não foi alterada nas plantas tratadas com extrato de Abl-28 e com o aSm. No entanto, plantas de berinjela tratadas com Abl-11 exibiram uma aumento na atividade de fenilalaniana amônia-liase e de polifenoloxidase, enquanto que a atividade de quitinase não foi alterada. Com base nos resultados, ficou evidenciado que o aSm e os isolados Abl-11 e Abl-28 de A. blazei apresentam potencial para induzir resistência em berinjela contra R. solanacearum.

The bacterial wilt, caused by Ralstonia solanacearum, is an important disease for eggplants, which control is difficult. Induction of resistance in plants is a promising method for disease control. Fruiting bodies of Agaricus blazei and Lentinula edodes have substances that exhibit antibiotic activity or are able of acting as elicitors of resistance in plants. The objectives of the present work were to verify the effect of aqueous extracts from the mushrooms and the plant activator acibenzolar-S-methyl (aSm) on in vitro bacterial growth and to control bacterial wilt as well as to investigate the activity of certain enzymes. The inhibitory effect on the pathogen was evaluated by using different concentrations of aqueous extracts. The induced resistance was studied in plants treated with the biological or chemical inducers, by measuring the intensity of wilt and alterations in some defense-related enzymes. The results showed that the isolates of A. blazei and L. edodes, used in several dilutions, did not inhibit in vitro bacterial growth. The extracts of the isolates Abl-11 and Abl-28 from A. blazei (15%, v/v) and aSm (0,05 g/L) caused significant reduction in the occurrence of wilted leaves, when applied two days before inoculation. Plants treated with aSm or aqueous extracts of Abl-11 and Abl-28 exhibited increased peroxidase activity. The chitinase, phenylalanine ammonia-lyase and polyphenoloxidase activities did not change in plants treated with Abl-28 and aSm. However, plants treated with Abl-11 exhibited increased phenylalanine ammonia-lyase and polyphenoloxidase activities, while the chitinase activity was not affected. Based upon the results, it was shown that the aSm and the isolates Abl-11 and Abl-28 of A. blazei exhibited a potential to induce resistance in eggplants against R. solanacearum.

Among the secondary detection effects in gamma-ray spectroscopy with HPGe detectors that reduce the peak area and must be properly taken into account in accurate measurements, the less well known is counting loss by beta and gamma-ray sum coincidence. The fraction of lost counts was estimated assuming that a photon detection event can sum either with the coincident beta-ray or its bremsstrahlung in the detector capsule or surrounding materials. The beta-ray was tracked through all the materials between source and detector. The result was calculated as a sequence of integral expressions evaluated numerically, without resorting to simulation. It is shown that the counting losses due to this effect are negligible for most calibration sources in typical detector arrangements.

The biggest constraint in the RPCs operation is the drop of their efficiency with the counting rate, consequence of charge gain decrease. This effect is normally attributed to the voltage drop on the dielectrics, although not supported by quantitative measurement. In this work we present the first results of a two-parameter analysis of the charge pulse height time variation from a cylindrical resistive detector, operating in proportional regime, under high irradiation rates. The dynamic behaviour of this detector was investigated through the determination of the time decay constants related to its stationary condition, where the charge gain becomes constant. To perform this study, a data acquisition system, which allows the users to observe in real-time the temporal variation of the energy spectrum, was specially designed. The fitting of the peak centroid position as a function of time, obtained for rates range from 220Hz up to 1230Hz, showed it can be described by a sum of two exponentials plus a constant term, what is in accordance to the dielectric delayed polarization processes.