Efeito da época da queima na dinâmica de campo sujo de Cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo da cinética de degradação da resina benzoxazina e seus compósitos nanoestruturados

The benzoxaxine resin is a new class of thermoset phenolic resin, which is presenting, in the lasts decades, a great application in the aircraft industry due mainly to its excellent mechanical and thermal properties. This resin associates the mechanical properties of epoxy resin with the thermal and flame retardant properties of phenolic resin. In this context, they are considered polymers of high performance and they are excellent candidates to replace the current thermoset matrices used in the processing of high performance composites. Thus, in this study nanostructured composites Benzoxazine/CNT were produced at different concentrations of functionalized and non-functionalized CNT (0,1%; 0,5% and 1,0% w/w). The thermal stability of the benzoxazine resin and its nanostructured composites was studied using thermogravimetry (TGA) and degradation kinetic model Ozawa-Wall-Flynn (O-W-F). The thermal characterization also included differential scanning calorimetry (DSC) and dynamic-mechanical analysis, infrared spectroscopy with Fourier transform (FTIR) and scanning electron microscopy (SEM).The introduction of non-functionalized CNT at low concentrations resulted in nanostructured composites with better thermal properties in relation to the neat resin. For all cases, however, the dispersion of CNT in the matrix was ineffective

Termometria em chamas utilizando a técnica de espalhamento Rayleigh

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo da qualidade da gasolina tipo A e sua composição química empregando análise de componentes principais

The type A gasoline samples were analyzed by gas chromatography with flame ionization detector (GC-FID) which allowed quantifying and classifying of the various compounds into different classes of hydrocarbons. Several physicochemical parameters were evaluated according to the official methods in order to compare the results obtained against the limits established by the Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (ANP, 2011). Additionally, principal component analysis (PCA) was applied to discriminate the samples studied, which revealed the separation of four groups according to their chemical composition determined in samples collected from the eight fuel distributors in the State of Pará.

Estudo morfológico do efeito radioprotetor da vitamina E (dl-alfa-tocoferil) na reparação tecidual em ratos

Esta pesquisa teve por finalidade avaliar a ação da vitamina E como radioprotetora no processo de reparação tecidual em ratos, após sofrerem um procedimento cirúrgico, que consistiu da produção de uma ferida na região dorsal anterior. Os animais foram divididos em cinco grupos: grupo CO (controle) - constituído de animais em que foi produzida somente a ferida; grupo VE - pré-tratamento com vitamina E (90 UI); grupo IR - irradiação três dias após a cirurgia; grupo VEIR - pré-tratamento com 90 UI de vitamina E e irradiação de suas bordas três dias após a cirurgia; grupo OIR - pré-tratamento com óleo de oliva e irradiação de suas bordas três dias após a cirurgia. A ação radioprotetora da vitamina E foi avaliada pela coloração por hematoxilina-eosina para análise morfológica do tecido de granulação, aos 4, 7, 14 e 21 dias após a cirurgia. A análise dos resultados mostrou que o retardo no processo de reparação tecidual causado por 6 Gy de radiação de elétrons com feixe de 6 MeV não ocorreu no grupo de animais que recebeu vitamina E, mostrando-se esta substância efetiva como radioprotetora.

Efeito da época da queima na dinâmica de campo sujo de Cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo da cinética de degradação da resina benzoxazina e seus compósitos nanoestruturados

The benzoxaxine resin is a new class of thermoset phenolic resin, which is presenting, in the lasts decades, a great application in the aircraft industry due mainly to its excellent mechanical and thermal properties. This resin associates the mechanical properties of epoxy resin with the thermal and flame retardant properties of phenolic resin. In this context, they are considered polymers of high performance and they are excellent candidates to replace the current thermoset matrices used in the processing of high performance composites. Thus, in this study nanostructured composites Benzoxazine/CNT were produced at different concentrations of functionalized and non-functionalized CNT (0,1%; 0,5% and 1,0% w/w). The thermal stability of the benzoxazine resin and its nanostructured composites was studied using thermogravimetry (TGA) and degradation kinetic model Ozawa-Wall-Flynn (O-W-F). The thermal characterization also included differential scanning calorimetry (DSC) and dynamic-mechanical analysis, infrared spectroscopy with Fourier transform (FTIR) and scanning electron microscopy (SEM).The introduction of non-functionalized CNT at low concentrations resulted in nanostructured composites with better thermal properties in relation to the neat resin. For all cases, however, the dispersion of CNT in the matrix was ineffective

Termometria em chamas utilizando a técnica de espalhamento Rayleigh

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Polycyclic aromatic hydrocarbons and petroleum biomarkers in Sao Sebastiao Channel, Brazil: Assessment of petroleum contamination

Polycyclic aromatic hydrocarbons (PAHs) and non-aromatic hydrocarbons (NAHs), including n-alkanes, isoprenoids and petroleum biomarkers (terpanes, hopanes, steranes and diasteranes), were quantified by gas chromatography with flame ionization and mass spectrometer detectors in sediment samples collected from the Sao Sebastiao Channel (SSC), Brazil, where the largest Brazilian maritime petroleum terminal is located The concentrations of total PAHs. total n-alkanes and petroleum biomarkers ranged from below the detection limits to 370 ng g(-1,) 28 mu g g(-1), 2200 ng g(-1) (dry weight), respectively. The analysis of PAN distribution suggested combustion sources of PAHs as the main input for these compounds with smaller amount from petroleum contamination The distribution of petroleum biomarkers undoubtedly demonstrated petroleum as a source of anthropogenic contamination throughout the region. The assessment of petrogenic sources of contamination in marine sediment is more challenging if only PAH analysis were carried out, which demonstrates that more stable hydrocarbons such as petroleum biomarkers are useful for investigating potential presence of petroleum (C) 2009 Elsevier Ltd. All rights reserved.

Speciation of butyltin derivatives in surface sediments of three southern Brazilian harbors

For the first time, organotin compounds were determined in surface sediment samples collected from Sao Francisco do Sul, Itajai-Navegantes and Imbituba Harbors, located in Santa Catarina State, Brazil. Butyltins (BTs) were determined by gas chromatography with a pulsed flame photometric detector (GC-PFPD) after being modified using the Grignard derivatization method. The concentrations of BTs derivatives ranged from n.d. to 1136.6 ng (Sn) g(-1) of dry weight (dw) sediment for tributyltin (TOT), n.d. to 394.4 ng (Sn)g(-1) dw for dibutyltin (DOT) and n.d. to 312.2 ng (Sn)g(-1) dw for monobutyltin (MBT). The highest concentration of total BTs was found at the Itajai-Acu River dockyard, indicating intense inputs of antifouling paints to the environment. The relative difference in the BTs levels is a particular characteristic of sediments from harbors and may be related to the shipyards and the boat traffic which still use TBT-based antifouling paints.

Results from a 15-year study on hydrocarbon concentrations in water and sediment from Admiralty Bay, King George Island, Antarctica

Admiralty Bay on the King George Island hosts the Brazilian, Polish and Peruvian research stations as well as the American and Ecuadorian field stations. Human activities in this region require the use of fossil fuels as an energy source, thereby placing the region at risk of hydrocarbon contamination. Hydrocarbon monitoring was conducted on water and sediment samples from the bay over 15 years. Fluorescence spectroscopy was used for the analysis of total polycyclic aromatic hydrocarbons (PAHs) in seawater samples and gas chromatography with flame ionization and/or mass spectrometric detection was used to analyse individual n-alkanes and PAHs in sediment samples. The results revealed that most sites contaminated by these Compounds are around the Brazilian and Polish research stations due to the intense human activities, mainly during the summer. Moreover, the sediments revealed the presence of hydrocarbons from different sources, suggesting a mixture of the direct input of oil or derivatives and derived from hydrocarbon combustion. A decrease in PAH concentrations occurred following improvement of the sewage treatment facilities at the Brazilian research station, indicating that the contribution from human waste may be significant.

Motor Activity and Depression Severity in Adolescent Outpatients

Objectives: The present study investigated the association between motor activity and severity of depression in 6 depressed adolescent outpatients. Method: Motor activity was assessed by actigraphy and the severity of depression was assessed weekly using the CDRS-R. The levels of motor activity were analyzed by considering activity parameters. Results: Among the parameters of motor activity studied, the mean total activity, the mean 24-hour activity levels, the mean waking activity, and the mean activity level between 12:00 and 18:00 h were inversely correlated with severity of depression. The means of the 10 most active hours tended toward a negative correlation with the depressive severity score. Conclusion: The results seem to suggest an association between motor activity level and severity of depression in adolescents. Nevertheless, in order to reach a more conclusive understanding, it would be necessary to replicate this study using a larger number of individuals as well as a longer observation period. Copyright (C) 2009 S. Karger AG, Basel

An Alternative Method for the Simultaneous Determination of Copper and Lead for Quality Control of Sugar Cane Spirit using a Nanotube-Based Sensor

The development of an electroanalytical method for simultaneous determination of copper and lead ions in sugar cane spirit (cachaca) using carbon paste electrode modified with ascorbic acid and carbon nanotubes (CPE-AaCNT) is described. Squarewave voltammetry (SWV) with anodic stripping was employed, and this technique was optimized with respect to the following parameters: frequency (50 Hz), amplitude (100 mV) and scan increment (9 mV). The analytical curves were linear in the range from 0.0900 to 7.00 mg L-1 for lead and copper. The limits of detection were 48.5 and 23.9 mu g L-1 for lead and copper, respectively. The developed method was applied to the simultaneous determination of copper and lead in five commercial samples of sugar cane spirit. The results were in good agreement with those obtained by F AAS/GF AAS (flame atomic absorption spectrometry/graphite furnace atomic absorption spectrometry) and showed that CPE-AaCNT can be successfully employed in the simultaneous determination of these metals in real sugar cane spirit samples.

From Sample Processing to Quantification: A Full Electrochemical Approach for Neutral Analyte Derivatization, Capillary Electrophoresis Separation, and Contactless Conductivity Detection

A thin-layer electrochemical flow cell coupled to capillary electrophoresis with contactless conductivity detection (EC-CE-(CD)-D-4) was applied for the first time to the derivatization and quantification of neutral species using aliphatic alcohols as model compounds. The simultaneous electrooxidation of four alcohols (ethanol, 1-propanol, 1-butanol, and 1-pentanol) to the corresponding carboxylates was carried out on a platinum working electrode in acid medium. The derivatization step required 1 min at 1.6 V vs. Ag/AgCl under stopped flow conditions, which was preceded by a 10 s activation at 0 V. The solution close to the electrode surface was then hydrodynamically injected into the capillary, and a 2.5 min electrophoretic separation was carried out. The fully automated flow system operated at a frequency of 12 analyses per hour. Simultaneous determination of the four alcohols presented detection limits of about 5 x 10(-5) mol As a practical application with a complex matrix, ethanol concentrations were determined in diluted pale lager beer and in nonalcoholic beer. No statistically significant difference was observed between the EC-CE-(CD)-D-4 and gas chromatography with flame ionization detection (GC-FID) results for these samples. The derivatization efficiency remained constant over several hours of continuous operation with lager beer samples (n = 40).

Positive effects of zinc supplementation on growth, GH, IGF1, and IGFBP3 in eutrophic children

Zinc is an essential micronutrient for growth and development. Its deficiency causes growth retardation in children and adolescents. The present study analyzes the effect of zinc on growth hormone (GH) secretion, insulin-like growth factor 1 (IGF1), and insulin-like growth factor-binding protein 3 (IGFBP3) in normal children before puberty. Thirty normal children were studied, 15 boys and 15 girls, aged 6-9 years. They were orally supplemented with 5 mg Zn/day for 3 months and 0.06537 mg Zn/kg body weight was injected before and after oral supplementation. Dietary intake and anthropometric measurements were assessed at baseline and end of study. Plasma GH levels increased during intravenous zinc administration and IGF1 and IGFBP3 increased after oral zinc supplementation. There was a positive correlation between the areas under the curves of GH and zinc after oral supplementation. Zinc supplementation was possibly effective in improving the body zinc status of the children, secretory levels of IGF1 and IGFBP3, GH potentialization, and height.