ESTUDO DO ENVELHECIMENTO ACELERADO DE UM NOVO ÓLEO VEGETAL ISOLANTE, À BASE DE PINHÃO-MANSO, PARA USO EM TRANSFORMADORES ELÉTRICOS

O presente trabalho foca na avaliação de um novo fluido isolante vegetal para transformadores elétricos de potência à base do óleo de Jatropha curcas. Foi proposta uma metodologia para ensaios de envelhecimento acelerado do óleo, a fim de verificar o comportamento deste em condições extremas, comparando-o com fluido comercial BIOTEMP®. Utilizou-se óleo de Jatropha curcas extraído e processado neste estudo, cujas propriedades preencheram todas as especificações das normas ASTM D6871 e ABNT NBR 15422 para óleos vegetais isolantes novos para transformador. Os ensaios de envelhecimento acelerado foram realizados utilizando os dois óleos em diferentes condições: sem aditivos; com a adição de fio de cobre e papel Kraft; e com a adição destes dois componentes mais  antioxidantes. Os antioxidantes utilizados foram o ácido ascórbico, BHT (di-terc-butil-metilfenol) e TBHQ (terc-butil hidroquinona). O melhor resultado para o óleo de Jatropha curcas (menor viscosidade e menor variação do índice de acidez) foi obtido na presença de TBHQ 2 %m/m óleo, fio de cobre e papel kraft. No entanto, o BIOTEMP® foi mais estável do que o óleo de Jatropha curcas. Este estudo indicou que o óleo de Jatropha curcas tem potencial para ser usado em transformadores de potência. No entanto, os testes de envelhecimento acelerado precisam ser refinados

Devulcanization of styrenebutadiene (SBR) waste tire by controlled oxidation

This work describes the devulcanization of vulcanized SBR (Styrene Butadiene Rubber) based on controlled oxidation with nitric acid. IR, ¹H and 13C-NMR, CHN elemental analyses, TG, GPC and TPD-MS (Temperature Programmed Decomposition-Mass Spectrometry) experiments suggest that nitric acid promotes two processes: (i) devulcanization by oxidation of the sulfide crosslinks and (ii) oxidation of the carbon framework leading to the formation of -COOH and -NO2 groups. Under aggressive conditions (HNO3, reflux) the polymer chain is strongly oxidized and fragmented to a highly oxygenated low molecular weight fraction, which is soluble in water

Changes in the essential oil composition of leaves of Echinodorus macrophyllus exposed to

Leaves of Echinodorus macrophyllus (Kunth) Micheli, Alismataceae, were exposed to different doses of γ-radiation (0.00, 1.00, 3.00, 5.00, 10.00, and 20.00 kGy) and the chemical composition of their essential oils was investigated. The extractive process of the essential oil was more favored when the leaves were irradiated. The essential oil components were identified by correlation between GC-FID data and retention parameters obtained from the Kováts method. Moreover, GC-MS analyses of the essential oils were correlated with fragmentation profiles in the NIST standard mass fragmentation data bank. The essential oil of E. macrophyllus contains biologically active constituents of different chemical classes. Acyclic monoterpenes and sesquiterpenes showed increase in concentration when the leaves were exposed to γ-radiation. On the other hand, the component concentrations of some chemical classes were lightly decreased, i.e., for bicyclic monoterpenes, diterpenes, triterpenes, carboxylic esters, and carotenoid derivatives

Changes in the essential oil composition of leaves of Echinodorus macrophyllus exposed to γ-radiation

Abstract: Leaves of Echinodorus macrophyllus (Kunth) Micheli, Alismataceae, were exposed to different doses of γ-radiation (0.00, 1.00, 3.00, 5.00, 10.00, and 20.00 kGy) and the chemical composition of their essential oils was investigated. The extractive process of the essential oil was more favored when the leaves were irradiated. The essential oil components were identified by correlation between GC-FID data and retention parameters obtained from the Kováts method. Moreover, GC-MS analyses of the essential oils were correlated with fragmentation profiles in the NIST standard mass fragmentation data bank. The essential oil of E. macrophyllus contains biologically active constituents of different chemical classes. Acyclic monoterpenes and sesquiterpenes showed increase in concentration when the leaves were exposed to γ-radiation. On the other hand, the component concentrations of some chemical classes were lightly decreased, i.e., for bicyclic monoterpenes, diterpenes, triterpenes, carboxylic esters, and carotenoid derivatives

Effect of Arrabidaea chica extracts on the Ehrlich solid tumor development

The aim of this study was to investigate the effect of Arrabidaea chica (Humb. & Bonpl.) B. Verl., Bignoniaceae, extracts on Ehrlich solid tumor development in Swiss mice. Leaves of A. chica were extracted with two distinct solvents, ethanol and water. The phytochemical analysis of the extracts indicated different classes of secondary metabolites like as anthocyanidins, flavonoids, tannins and saponins. Ethanol (EE) and aqueous (AE) extracts at 30 mg/kg reduced the development of Ehrlich solid tumor after ten days of oral treatment. The EE group presented increase in neutrophil count, α1 and β globulin values, and decrease of α2 globulin values. Furthermore, EE reduced the percentage of CD4+ T cells in blood but did not alter the percentage of inflammatory mononuclear cells associated with tumor suggesting a direct action of EE on tumor cells. Reduced tumor development observed in AE group was accompanied by a lower percentage of CD4+ T lymphocytes in blood. At the tumor microenvironment, this treatment decreased the percentage of CD3+ T cells, especially due to a reduction of CD8+ T subpopulation and NK cells. The antitumor activity presented by the AE is possibly related to an anti-inflammatory activity. None of the extracts produced toxic effects in animals. In conclusion, the ethanol and aqueous extracts of A. chica have immunomodulatory and antitumor activities attributed to the presence of flavonoids, such as kaempferol. These effects appear to be related to different mechanisms of action for each extract. This study demonstrates the potential of A. chica as an antitumor agent confirming its use in traditional popular medicine

Chemical profile, toxicity, anti-acetylcholinesterase and antimicrobial activity of essential oil from hyptis dilatata leaves

The aim of this study was to evaluate the influence of seasonality on the chemical composition of the essential oil from Hyptis dilatata leaves, to perform biological activity assays such as antimicrobial, inhibition of acetylcholinesterase enzyme and to evaluate the toxicity of the essential oil using Artemia salina as indicator on the test. Hyptis dilatata leaves were collected in rainy and dry seasons, in the morning, in the afternoon and in the evening. It was extracted by hydrodistillation using the extractor of Clevenger condenser double Spell model. The essential oil analysis resulted in 22 chemical components. The major constituents of the dry and rainy periods were a-pinene (18.7% in the night and 12.9% in the afternoon), 3-carene (26.5% and 19.9% in the night), fenchone (43% and 33.7% in the morning) and ß-caryophyllene 9.1% in the afternoon and 6.1% in the morning. The essential oil in vitro inhibited the acetylcholinesterase enzyme in 99.9% in the afternoon (rainy period) and 96.4% in the morning (dry period). Between the dry and rainy seasons, the lowest LC50 microbial activity in vitro was obtained for leaves collected during rainy season, in the morning period tested against the bacterium Staphylococcus aureus (LC50 78.1 mg mL-1). The cytotoxic activity of the essential oil of H. dilatata on Artemia salina showed LC50 results below 100 µg mL-1 and in the afternoon during the rainy period and at night in the dry period the results are above this value. Therefore, the chemical characterization and biological activities tests of essential oils showed promising results in the search for new active substances and the development of bioproducts of vegetable origin. Copyright © 2018, AIDIC Servizi S.r.l