On the performance of a dual-mode non-linear vibration energy harvesting device

The research trend for harvesting energy from the ambient vibration sources has moved from using a linear resonant generator to a non-linear generator in order to improve on the performance of a linear generator; for example, the relatively small bandwidth, intolerance to mistune and the suitability of the device for low-frequency applications. This article presents experimental results to illustrate the dynamic behaviour of a dual-mode non-linear energy-harvesting device operating in hardening and bi-stable modes under harmonic excitation. The device is able to change from one mode to another by altering the negative magnetic stiffness by adjusting the separation gap between the magnets and the iron core. Results for the device operating in both modes are presented. They show that there is a larger bandwidth for the device operating in the hardening mode compared to the equivalent linear device. However, the maximum power transfer theory is less applicable for the hardening mode due to occurrence of the maximum power at different frequencies, which depends on the non-linearity and the damping in the system. The results for the bi-stable mode show that the device is insensitive to a range of excitation frequencies depending upon the input level, damping and non-linearity.

Effect of Artemisia annua L. leaves essential oil and ethanol extract on behavioral assays

Artemisia annua tem sido utilizada tradicionalmente para o tratamento de malária e febre na China devido à presença do princípio ativo, artemisinina. O presente trabalho avaliou a atividade central de do óleo essencial obtido por hidrodestilação e do extrato etanólico bruto de folhas frescas de A. annua em modelo in vivo como parte de um screening farmacológico dessa espécie. Sono induzido por pentobarbital, nado forçado e o ensaio de campo aberto são modelos de estudo conhecidos para o estudo de fármacos sobre depressão induzida. A administração do óleo essencial ou extrato bruto etanólico de A. annua aumentaram o tempo de imobilidade no teste do nado forçado. Por outro lado, diminuíram outros parâmetros no campo aberto, como ambulação, exploração, o ato de lamber as patas ou se lamber. Ambos produtos aumentaram o tempo de sono induzido por pentobarbital, com o óleo essencial apresentando um efeito superior ao do extrato. Pela análise dos resultados, é possível sugerir que tanto o extrato bem como o óleo essencial podem atuar como depressores do Sistema Nervoso Central (SNC).

The mutagenic potential of Clusia alata (Clusiaceae) extract based on two short-term in vivo assays

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Assessment of the potential genotoxic risk of medicinal Tamarindus indica fruit pulp extract using in vivo assays

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alcohol use disorders in patients with obsessive-compulsive disorder: The importance of appropriate dual-diagnosis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Antigen otoxicity of Agaricus blazei mushroom organic and aqueous extracts in chromosomal aberration and cytokinesis block micronucleus assays in CHO-k1 and HTC cells

Agaricus blazei (Ab) has become popularly known for its medicinal properties. Scientifically, it has been tested with regard to its capacity to protect genetic material against damage. We examined different organic extracts (methanolic extract-ME, hexanic extract-HE and n-butanolic extract-BE) and an aqueous extract (AE) of Ab, for their capacity to induce DNA damage as well as for their protective effect. Genetic damage was determined by the chromosomal aberration assay (CA) in CHO-k1 cells for all extracts and the cytokinesis block micronucleus assay (CBMN) in non drug-metabolizing (CHO-k1) and drug-metabolizing (HTC) cell lines for extract BE only. The extracts did not show clastogenicity but showed anticlastogenicity. The greatest percent reduction obtained were with BE (105%) and AE (126%) treatments in CA. BE treatment did not display genotoxicity in CHO-k1, but was genotoxic in HTC. However, BE was shown to be antigenotoxic causing decreased micronucleus frequency in HTC and CHO-k1 cells. These results suggest that all the extracts contained protective substances, but in some cases they could show a genotoxic effect with regard to metabolism. Therefore, these findings warrant caution in the use of this mushroom by the population. (c) 2005 Elsevier Ltd. All rights reserved.

Urinary fluoride output in children following the use of a dual-fluoride varnish formulation

Objective: This study evaluated the bioavailability of fluoride after topical application of a dual-fluoride varnish commercially available in Brazil, when compared to Duraphat T. Material and methods: The urinary fluoride output was evaluated in seven 5-year-old children after application of the fluoride varnishes, in two different phases. In the first phase (I), children received topical application of the fluoride varnish Duofluorid XII (2.92% fluorine, calcium fluoride + 2.71% fluorine, sodium fluoride, FGM (TM)). After 1-month interval (phase II), the same amount (0.2 mL) of the fluoride varnish Duraphat (2.26% fluorine, sodium fluoride, Colgate T) was applied. Before each application all the volunteers brushed their teeth with placebo dentifrice for 7 days. Urinary collections were carried out 24 h prior up to 48 h after the applications. Fluoride intake from the diet was also estimated. Fluoride concentration in diet samples and urine was analyzed with the fluoride ion-specific electrode and a miniature calomel reference electrode coupled to a potentiometer. Data were tested by ANOVA and Tukey's post hoc test (p < 0.05). Results: There were significant differences in the urinary fluoride output between phases I and II. The use of Duofluorid XII did not significantly increase the urinary fluoride output, when compared to baseline levels. The application of Duraphat caused a transitory increase in the urinary fluoride output, returning to baseline levels 48 h after its use. Conclusions: The tested varnish formulation, which has been shown to be effective in in vitro studies, also can be considered safe.