Estudo da decomposição térmica de propelente sólido compósito de baixa emissão de fumaça

The thermal decomposition of hydroxyl-terminated polybutadiene (HTPB)/ammonium nitrate (AN) based propellants, so called smokeless formulations, and raw materials were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). The thermoanalytical profile of different components and of propellant were evaluated and the Arrhenius parameters for the thermal decomposition of the propellant sample were determined by the Ozawa method. The kinetic parameters of the thermal decomposition of propellant samples were determined by DSC measurements. The values obtained for activation energy (Ea) and pre-exponential factor were 163 kJ mol-1 and 1.94x10(6) min-1.

Composição química dos óleos essenciais das folhas de seis espécies do gênero Baccharis de "Campos de Altitude" da mata atlântica paulista

The essential oils from the leaves of six species of the Baccharis genus (B. dracunculifolia, B. microdonta, B. regnelli, B. schultzii, B. trimera, and B. uncinella), collected in the "Campos de Altitude" of the Atlantic Forest (SP), were extracted using hydrodistillation procedures and analyzed by GC and GC/MS. There was a predominance of sesquiterpenes in all studied oils as b-elemene in B. dracunculifolia and B. regnelli, a-humulene in B. trimera, g-gurjunene in B. schultzii, bicyclogermacrene in B. regnelli, d-cadinene in B. regnelli and B. uncinella, spathulenol in B. schultzii, caryophyllene oxide in B. microdonta and guaiol in B. uncinella. However, a high amount of monoterpenes was also observed in B. uncinella (a-pinene), B. regnelli (d-car-3-ene) and B. schultzii (limonene). The chemical compounds of the essential oils of B. schultzii, B. regnelli and B. microdonta are described for the first time in this work.

Efeito do 1-metilciclopropeno sobre a emissão dos ésteres voláteis de bananas ao longo do amadurecimento

Fresh green bananas (Musa sp., subgroup Prata) were treated with a dose of only 90 ηg g-1 of 1-MCP for 13 hours and the evolution of the volatile compounds along the ripeness was studied. A method to quantify the emission of esters was developed by cryogenic headspace and gas chromatography. Esters of acetate, butyrate, isobutyrate and isovalerate were found as major compounds. The application of the 1-MCP for 13 hours delayed the appearance of the coloration 8 of the peel for 3 days and decreased quantitatively in about 46% the total production of esters in the banana until the 15° day of harvested.

químicos das folhas de Qualea grandiflora: atribuição dos dados de RMN de dois flavonóides glicosilados acilados diastereoisoméricos

Phytochemical investigation from leaves of the Qualea grandiflora (Vochysiaceae) resulted in the isolation and identification of kaempferol-3-O-α-L-(4"-E-p-coumaroyl)-rhamnoside, kaempferol-3-O-α-L-(4"-Z-p-coumaroyl)-rhamnoside, squalene, phytol, lupeol, α-amyrin, β-amyrin, sitosterol, sitostenone, sitosterol-3-O-β-D-glucopyranoside, ursolic and oleanolic acids. The structures of the compounds were identified by 1D- and 2D-NMR experiments, mass and UV spectrometry and comparison with literature data.

Constituintes químicos e avaliação do potencial antiinflamatório e antioxidante de extratos das folhas de Chomelia obtusa Cham. & Schltdl. (Rubiaceae)

The phytochemical investigation of Chomelia obtusa leaves led to the isolation of four triterpenes (3-O-β-D-quinovopyranosyl-28-O-β-D-glycopyranosyl quinovic acid, 3-O-β-D-quinovopyranosyl-28-O-β-D-glycopyranosyl cincholic acid, and a mixture of ursolic and oleanolic acids), two flavonoids (3-O-β-D-glycopyranosyl quercetin, 3-O-[α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranoside] quercetin), besides bornesitol and a mixture of 3,5- and 4,5-O-dicaffeoyl quinic acids. The structures of the isolated compounds were assigned on the basis of spectroscopic data, including two-dimensional NMR methods. The anti-inflammatory and antioxidant activities of the crude methanolic extract and of its fractions were evaluated. This is the first report on the chemical and biological investigation of the Chomelia genus.

Flavonóides, norisoprenóides e outros terpenos das folhas de Tapirira guianensis

From hexane fraction of methanol extract of leaves of Tapirira guianensis (Anacardiaceae) were obtained lupeol, 24-methylenecycloartan-3-ol, phytol, α-amyrin, β-amyrin, sitosterol, sitostenone, glycosyl sitosterol, as well as sitosterol esterified with palmitic and stearic acids. Phytol, α-amyrin and β-amyrin esterified with fatty acids were also identified from same extract. The EtOAc extract besides the norisoprenoids (6S,7E,9S)-6,9-dihydroxy-megastigma-4,7-dien -3-one 9-O-β-glucopyranoside and (6S,7E,9R)-6,9-dihydroxy-megastigma-4,7-dien-3-one 9-O-β-glucopyranoside also afforded kaempferol 3-O-rhamnoside, kaempferol 3-O-arabinofuranoside, quercetin 3-O-rhamnoside, and kaempferol. The structural elucidation of isolated compounds were based on UV, IR, MS, ¹H and 13C NMR data analysis.

Técnica de bombeio e prova para medidas de absorção de estado excitado e de emissão estimulada, em materiais sólidos dopados com íons terras raras

Rare earth ion doped solid state materials are the most important active media of near-infrared and visible lasers and other photonic devices. In these ions, the occurrence of Excited State Absorptions (ESA), from long lived electronic levels, is commonplace. Since ESA can deeply affect the efficiencies of the rare earth emissions, evaluation of these transitions cross sections is of greatest importance in predicting the potential applications of a given material. In this paper a detailed description of the pump-probe technique for ESA measurements is presented, with a review of several examples of applications in Nd3+, Tm3+ and Er3+ doped materials.

Constituintes químicos voláteis das folhas e galhos de Zanthoxylum syncarpum Tull.

The essential oils of the leaves and twigs from Zanthoxylum syncarpum Tull. were examined by GC/MS and GC-FID. Variation in the oil composition relative to the harvesting time was also described. The major components in the leaves oils were limonene (23.1-47.3%) and myrcene (4.8-10.8%). In the oils of twigs, the main components were ar-curcumene (12.8-18.1%), E-β-farnesene (9.1-9.7%) and β-caryophyllene (9.2-9.3%). This paper describes for the first time the composition of the essential oil of the twigs from Z. syncarpum.

Atividade antioxidante de extratos e taninos condensados das folhas de Maytenus ilicifolia Mart. ex Reiss.

Maytenus ilicifolia (Celastraceae) is a native plant of South America and popularly known as "espinheira-santa". The aim of this study was to evaluate the antioxidant capacity of extracts and isolated compounds from this plant. The antioxidant activity of the crude and semipurified extracts and isolated compounds was evaluated through DPPH-radical and phosphomolybdenum-complex assays. By both methods, the ethyl-acetate fraction demonstrated better antioxidant capacity compared with vitamin C and trolox. In the compounds, the higher the number of hydroxyls, the greater the antioxidant activity. In addition, stereochemistry influenced antioxidant activity, i.e., compounds with 2R,3R showed greater activity than those with 2R,3S.

Salicilatos isolados de folhas e talos de Salix martiana Leyb. (Salicaceae)

Salix martiana Leyb. is an endemic species from the Amazon river floodplain areas (varzeas), of the State of Amazonas. Stems and leaves were extracted with dichloromethane, methanol and hydro-alcohol and these extracts were fractionated by using conventional chromatographic techniques. The major substances isolated, salicin and trichocarposide (6-0-p-coumaroyl salicin), were determined through analyses of NMR 1D (¹H and 13C) and NMR 2D (gHSQC and gHMBC). These compounds were isolated for the first time in Salix martiana Leyb. (Salicaceae). The percentage of these compounds in S. martiana is very high. The extracts were analyzed for their DPPH antioxidant capacity and the methanolic from the leaves and the hydro-alcoholic from the stems were the more active.

Constituintes químicos e atividade antioxidante de extratos das folhas de Terminalia fagifolia Mart. et Zucc

Phytochemical investigation of ethanolic leaves extracts of T. fagifolia led to the isolation of (+)-catechin, sitosterol-3-O-β-D-glucopyranoside, α- and β-tocopherol, a mixture of lupeol, α- and β-amyrin, sitosterol and a mixture of glicosid flavonoids (CP-13). The structures of these compounds were identified by ¹H and 13C NMR spectral analysis and comparison with literature data. Absolute configuration of the catechin was determinate by circular dichroism. Antioxidant activity (EC50), evaluated by 2,2-diphenyl-1-picrylhidrazyl (DPPH) assay system, decreased in the order: (+)-catechin > hydroalcoholic fraction > CP-13 > aqueous fraction > EtOH extract.

Concentrações de amônio na água da chuva e estimativa de emissão de amônia de rebanhos domésticos de Pinheiro e Viana, Baixada Maranhense

Rainwater samples (bulk deposition samples) were collected in Pinheiro and Viana. Rainwater pHs were higher than the range usually expected for unpolluted rain (5.0-5.6). The highest values were found in the beginning of the rainy season. High concentrations of ammonium found in the rainwater samples could probably explain the high pHs. Grazing animals and other human activities, combined with soil characteristics and climatic conditions can be the potential factors controlling the rainwater concentrations of ammonium in Baixada Maranhense.

Enriquecimento de compostos fenólicos de folhas de Inga edulis por extração em fase sólida: quantificação de seus compostos majoritários e avaliação da capacidade antioxidante

A phenolic fraction was obtained from of the acetone-water-acetic acid extract of Inga edulis leaves, by liquid-liquid partition and SPE-C18 cartridges. This method provided an increase of 108, 66, 51, 50 and 36% of flavonols, proanthocyanidins, total polyphenols, gallotannins and flavanols, respectively. The major phenolics in purified fraction were procyanidin B2, catechin and myricetin-3-O-α-L-rhamnopyranoside, which achieved increases of 111, 47 and 45%, respectively, after SPE. Acid hydrolysis confirmed the presence of procyanidins, prodelphinidins and glycosylated flavonoids.

Óleos essenciais das folhas de Vernonia Remotiflora e Vernonia Brasiliana: composição química e atividade biológica

The chemical composition of the essential oils, obtained by hidrodistillation, from leaves of two Vernonia species (V. remotiflora and V. brasiliana), was determined by GC-FID and GC-MS. Both essential oils were predominantly constituted by sesquiterpenes (92.0 - 93.4%). The main constituents of the oil from V. brasilana were (E)-caryophyllene (36.7%), germacrene D (35.5%), and α-humulene (11.7%), while (E)-caryophyllene (42.2%) and bicyclogermacrene (20.0%) were the major ones in the oil from V. remotiflora. Although with moderate activity both oils showed acetylcholinesterase and antibacterial activities.

Emissão de óxido nitroso de estação de tratamento de esgoto de lodos ativados por aeração prolongada - estudo preliminar

Nitrous oxide emissions from an activated sludge plant which serves a research institute in Rio de Janeiro city were estimated from six unit processes (grit tank, sand trap, aeration tank, secondary settling tank, sludge recirculation line and aerobic digester sludge tank) and also from the plant effluent. Total estimated annual flux was 3.2 x 10(4) g N2O yr-1 of which about 90% was from the aeration tank. Emission factors estimated from population served, wastewater flow and nitrogen load (conversion ratio) were 13 g N2O person-1 yr-1, 9.0 x 10-5 g N2O Lwastewater-1 and 0.14%.