O espalhamento da luz pelos componentes fundamentais da matéria é o processo básico que torna visíveis os objetos. Dependendo da densidade dos elementos espalhadores, pode existir um cancelamento ou não da luz espalhada. Uma das manifestações do espalhamento é o denominado Efeito Tyndall, o qual consiste no espalhamento de luz por partículas em escala nanométrica dispersas num meio líquido. Este trabalho propõe explorar as características do espalhamento de luz através da análise do Efeito Tyndall produzido por nanopartículas de prata dispersas em água.

Light scattering is the physical phenomenon responsible among other things, of the blue color of the sky, the glow when fog is illuminated by a headlight, and basically the motive why we see every illuminated object. The density of the scatterers determines if the scattered light is canceled out or not. The Tyndall Effect is the scattering by objects with sizes smaller that the wavelength of light dispersed in a fluid. In this work we explore the properties of the scattered light through the Tyndall Effect observed with silver nanoparticles dispersed in water.

O presente estudo teve como objetivo a caracterização físico-química de amostras de mel de Apis mellifera coletadas nos municípios de Santa Helena e Terra Roxa, localizados na região oeste do Estado do Paraná, Brasil. Foram coletadas 40 amostras de mel, sendo 20 do município de Santa Helena e 20 de Terra Roxa (PR), coletadas diretamente com os apicultores, as quais foram submetidas a análises físico-químicas de umidade, acidez, pH, cinzas, condutividade elétrica e cor, a fim de verificar se as mesmas apresentavam-se em conformidade com a legislação nacional vigente (Instrução Normativa nº 11), além de conhecer o perfil físico-químico do mel das diferentes localidades, na safra 2008/2009. Os dados encontrados foram submetidos à análise de variância e teste F a 5% de significância. Os resultados apresentaram diferença significativa (P<0,05) apenas entre os valores de acidez, tendo o mel oriundo de Terra Roxa apresentado valor mais alto (33,45±7,7meq.kg-1) que o de Santa Helena (24,53±6,3meq.kg-1). Em sua maioria, as amostras analisadas encontraram-se dentro das especificações determinadas pela legislação para as características físico-químicas, com exceção do parâmetro de umidade, que, apesar de não ter apresentado diferença significativa entre os valores encontrados para os dois municípios, estavam acima do limite estabelecido pela legislação (20%) em 8 amostras do município de Santa Helena e em 7 de Terra Roxa, totalizando 37,5% das amostras. Essa característica pode ter deixado o produto mais susceptível à fermentação e pode ter sido ocasionada pela colheita imatura do mel.

This study aimed to physicochemically characterize the honey samples of Apis mellifera collected in Santa Helena and Terra Roxa counties, located in the western region of Paraná State, Brazil. Forty honey samples were collected, 20 in Santa Helena and 20 in Terra Roxa (PR) counties, directly from beekeepers, and were subjected to physico-chemical analyzes of moisture, acidity, pH, ashes, electrical conductivity and color, to verify whether they were in accordance with the existing national legislation (Instruction No. 11), in addition to knowing the physicochemical profile of different sites during the 2008/2009 season. The data were submitted to analysis of variance and F test at 5% significance level. The results showed significant differences (P<0.05) between values of acidity, and the honey samples from Terra Roxa presented a higher value (33.45±7.7 meq.kg-1) than Santa Helena (24 = 53±6.3 meq.kg-1). Most of the analyzed samples were within the specifications prescribed in the legislation for the physico-chemical parameters except for moisture, which despite having presented a significant difference between values obtained from two counties, were above the limits established by the legislation (20%) in eight samples in Santa Helena and seven in Terra Roxa counties, totaling 37.5%. This characteristic may have made the product more susceptible to fermentation, and may have been caused by harvesting immature honey.

Objetivou-se com este trabalho verificar a fungitoxicidade in vitro de extratos alcoólicos de própolis (EAP) sobre a germinação de esporos de Phakopsora euvitis e Pseudocercospora vitis e também sobre o crescimento micelial e esporulação de esporos de Elsinoe ampelina. Para o ensaio de inibição de germinação o EAP foi utilizado nas concentrações de 0,025; 0,05; 0,1; 0,2; 0,25 e 0,5%. Como testemunhas utilizaram-se água destilada, etanol 0,35% e fungicida azoxystrobin. No ensaio de crescimento micelial e esporulação foram utilizadas as concentrações de 0,05; 0,1; 0,2; 0,4; 0,5 e 1,0% de EAP. As testemunhas foram o meio de cultura batata-dextrose-ágar (BDA), BDA + 0,7% de etanol e o fungicida azoxystrobin. Os resultados obtidos permitiram concluir que o EAP possui baixa atividade antifúngica in vitro contra P. euvitis, P. vitis e E. ampelina, para as concentrações testadas.

The objective of this work was to verify the in vitro effect of alcoholic extracts of propolis (AEP) on the germination of spores of Phakopsora euvitis and Pseudocercospora vitis, and also on the mycelial growth and sporulation of Elsinoe ampelina. For the germination assay the AEP was used at concentrations of 0.025; 0.05; 0.1; 0.2; 0.25 and 0.5%. Distilled water, ethanol at 0.35% and the fungicide azoxystrobin were used as control treatments. For mycelial growth and sporulation the concentrations 0.05; 0.1; 0.2; 0.4; 0.5 and 1.0% of AEP were used. The control treatments were potato-dextrose-agar (PDA) medium, PDA + 0.7% ethanol and the fungicide azoxystrobin. The results showed that AEP has a low in vitro antifungal activity against P. euvitis, P. vitis and E. ampelina, for the tested concentrations.

Lead has been shown to produce cognitive and motor deficits in young rats that could be mediated, at least in part, by inhibition of the zinc-containing heme biosynthetic enzyme delta-aminolevulinate dehydratase (ALA-D). In the present study we investigated the effects of lead and/or zinc treatment during the second stage of rapid postnatal brain development on brain, kidney and blood ALA-D specific activity, as well as the negative geotaxis behavior of rats. Eight-day-old Wistar rats were injected intraperitoneally with saline, lead acetate (8 mg/kg) and/or zinc chloride (2 mg/kg) daily for five consecutive days. Twenty-four hours after treatment, ALA-D activity was determined in the absence and presence of DL-dithiothreitol (DTT). The negative geotaxis behavior was assessed in 9- to 13-day-old rats. Treatment with lead and/or zinc did not affect body, brain or kidney weights or brain- or kidney-to-body weight ratios of the animals. In spite of the absence of effect of any treatment on ALA-D specific activity in brain, kidney and blood, the reactivation index with DTT was higher in the groups treated with lead or lead + zinc than in the control group, in brain, kidney and blood (mean ± SEM; brain: 33.33 ± 4.34, 38.90 ± 8.24, 13.67 ± 3.41; kidney: 33.50 ± 2.97, 37.60 ± 2.67, 15.80 ± 2.66; blood: 63.95 ± 3.73, 56.43 ± 5.93, 31.07 ± 4.61, respectively, N = 9-11). The negative geotaxis response behavior was not affected by lead and/or zinc treatment. The results indicate that lead and/or zinc treatment during the second stage of rapid postnatal brain growth affected ALA-D, but zinc was not sufficient to protect the enzyme from the effects of lead in brain, kidney and blood.