Biodiesel is obtained from a renewable source and has been used as an alternative to fossil fuels. It has unsaturated fatty acid methyl esters that can degrade due to oxidation of the double bonds. The instability of biodiesel during storage may cause problems regarding the maintenance and operation of motors. This work evaluated the effect of several variables on the storage conditions of biodiesel:diesel blends. The study was performed using an experimental design, and the variables were water content in biodiesel (0.01, 0.05 and 0.09%), biodiesel content in diesel (5.0, 7.5 and 10.0%), time (15, 30 and 45 days) and temperature (30, 40 and 50 °C). The levels simulated actual Brazilian storage conditions. The degradation was evaluated based on direct measurement of methyl linoleate and methyl oleate in the blends by gas chromatography-mass spectrometry. These unsaturated fatty acid methyl esters are target compounds in the oxidation process. All experiments were carried out in sealed flasks. The results suggest that the restriction of oxygen limited the degradation of biodiesel in blends with higher percentage of the biofuel. The variables temperature, time and water content in biodiesel individually did not affect the degradation process within the range investigated at 95% confidence interval.

Importantes agentes para defesa contra armas de guerra química são reativadores da acetilcolinesterase humana (huAChE) inibida por compostos organofosforados neurotóxicos (OP), e precisam de uma permeabilidade razoável pela barreira hematoencefálica (HB). Neste trabalho, oximas neutras, que penetram HB melhor do que as oximas catiônicas atualmente utilizadas como agentes de defesa, foram testadas como reativadores da huAChE inibida com paraoxon usando o método de Ellman modificado e pralidoxima (2-PAM) como padrão positivo. A oxima neutra mais ativa foi a 2-tiofenoaldoxima, que reativou 93% da huAChE inibida, sendo 12% mais eficiente do que a 2-PAM. Os resultados mostraram que oximas neutras simples possuem potencial para atuarem como antídotos para intoxicação com OPs neurotóxicos, sugerindo maior investigação no desenvolvimento de agentes de defesa neutros.

Important defense agents against chemical warfare weapons, which are reactivators of human acetylcholinesterase (huAChE) inhibited by neurotoxic organophosphorus compounds (OP), need a reasonable permeation of the hematoencephalic barrier (HB). In this work, neutral oximes, which permeate HB better than the cationic oximes currently used as defense agents, were tested as reactivators of huAChE inhibited with paraoxon using the modified Ellman test with pralidoxime (2-PAM) as positive standard. The most active neutral oxime was (thiophen-2-yl)aldoxime, which reactivated 93% of the inhibited huAChE and was 12% more effective than 2-PAM. The results showed that simple neutral oximes have potential to function as antidotes for intoxication with neurotoxic OPs, suggesting further research on the development of neutral defense agents.

Investigou-se a influência da sazonalidade na composição do óleo essencial de folhas frescas de Eugenia neonitida Sobral e Eugenia rotundifolia Casar. (Myrtaceae) coletadas trimestralmente, assim como a atividade antioxidante do óleo essencial de folhas secas e a histoquímica foliar. Os componentes majoritários do óleo essencial de E. neonitida foram biciclogermacreno, germacreno D e β-cariofileno e os de E. rotundifolia foram n, β-pineno e β-cariofileno. Os óleos essenciais de ambas as espécies apresentaram principalmente hidrocarbonetos e álcoois cíclicos, sendo o óleo essencial de E. neonitida composto principalmente por sesquiterpenos e o de E. rotundifolia por monoterpenos. A precipitação parece influenciar na composição dos óleos essenciais de ambas as espécies. O óleo essencial de folhas secas apresentou baixa atividade antioxidante. Os testes histoquímicos evidenciaram que as cavidades secretoras armazenam soluções complexas e contêm, além dos óleos essenciais, outras classes de lipídeos.

The seasonality influence on the essential oil composition of trimestrially collected fresh leaves of Eugenia neonitida Sobral and Eugenia rotundifolia Casar. (Myrtaceae) was investigated, as well as the antioxidant activity of dried leaves essential oils, and the leaf histochemistry. Eugenia neonitida essential oil major compounds were bicyclogermacrene, germacrene D, and β-caryophyllene. Eugenia rotundifolia major compounds were α-pinene, β-pinene, and β-caryophyllene. The essential oils of both species were mainly composed by cyclic hydrocarbons and alcohols; sesquiterpenes in E. neonitida and monoterpenes in E. rotundifolia. Precipitation appears to influence both species essential oils composition. Essential oils from dried leaves exhibited weak antioxidant activities. Both species have presented secretory cavities filled with a complex solution of essential oils and other lipid classes, according to histochemical tests.