Estudo e desenvolvimento de sensores biomiméticos baseados em materiais carbonáceos modificados com ftalocianinacobalto (II) para detecção amperométrica de metribuzin

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ancoragem de complexos de rutênio com ligantes siliados em sílica mesoporosa obtida via pirólise de spray

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência dos parâmetros de processamento por RTM no volume de vazios em compósitos carbono/epóxi

Pós-graduação em Engenharia Mecânica - FEG

Detecção de anilinas substituídas, em filmes de hexacianoferratos, com microbalança de cristal de quartzo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Characterization and distribution of pyrogenic carbon in a fraction of archaeological black earth from Caxiuanã

This study aims to determine the atomic ratio of O/C in an archaeological black earth (ABE) profile of the Ilha de Terra site, a region of Caxiuanã in the Pará State, Brazil, to determine the types of pyrogenic carbon (PyC) particles and to infer the source of biomass and burning temperature necessary to produce the PyC. The O/C ratios were monitored using scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS). The results indicated atomic ratios for clay, silt and fine sand fractions that were between those registered for the PyC particles types: condensed combustion (CC) (0.09, 0.1, 0.13), charcoal (0.32, 0.31, 0.34) and char (0.43, 0.45, 0.52). CC is the predominant type of particle found because of the high firing temperature (> 350 °C), which is consistent with the probable biomass sources of wood, cellulose and lignin.

Effect of colloidal silica on the mechanical properties of fiber-cement reinforced with cellulosic fibers

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

Mineralization of poly(epsilon-caprolactone)/adipate modified starch blend in agricultural soil

The biodegradability properties of poly(epsilon-caprolactone) (PCL) and modified adipate-starch (AS) blends, using Edenol-3203 (E) as a starch plasticizer, were investigated in laboratory by burial tests of the samples in previously analyzed agricultural soil. The biodegradation process was carried out using the respirometric test according to ASTM D 5988-96, and the mineralization was followed by both variables such as carbon dioxide evolution and mass loss. The results indicated that the presence of AS-E accelerated the biodegradation rate as expected.

Fractografia quantitativa: correlação entre dimensão fractal e tenacidade à fratura em compósitos fibra de carbono/epóxi

The fracture surfaces express the sequence of events of energy release due to crack propagation by linking the relief of the fracture to the loading stresses. This study aims to evaluate the heterogeneity of the critical zone for the advancement of the crack along its entire length in a thermoset composite carbon fiber and epoxy matrix, fractured in DCB testing (Double Cantilever Beam) and ENF (End-Notched Flexure). Investigations were made from image stacks obtained by optical reflection of extended depth from focus reconstruction. The program NIH Image J was used to obtain elevation map and fully focused images of the fracture surface, whose topographies were quantitatively analyzed. The monofractal behavior for DCB samples was assessed as being heterogeneous along the crack front and along the crack for all the conditionings. For the samples fractured in ENF test, there was a strong positive correlation to the natural condition, considering the fibers at 0° for the monofractal dimension and structural dimension (Df and Ds). For fibers at 90° to crack propagation, there was a moderate positive correlation for the textural dimension of natural condition. However, for the samples under ultraviolet condition and those subjected to thermal cycles, there was no correlation between the fractal dimension and fracture toughness in mode II

Avaliação de sistemas de pultrudados com diferentes tipos de matrizes para aplicação em cabos condutores

In the last decades it has been observed a substantial developing of the electrical energy demand in the societies all over the World. In consequence the electrical energy distribution companies are increasing the quantity of electrical energy through the electrical energy conductor cables, which had grown the sag in the towers of energy transmission. Furthermore, the construction of more transmission towers brings a lot of troubles due environmental protection laws. In this way, looking forward to increase the quantity of electrical energy transmitted through electrical cables conductors, reduce the need of constructing new transmission towers and the sag in them, we suggest in this work the replace of the traditional core of the conductors cables commonly used, made of steel, by a core made by a composite material, which one is made by carbon fibers pultruded with polymeric resins as matrix. In a order to evaluate if the resins more commonly used in structural composites can be applied as matrix to make possible to use the composite material as a core, we made carbon fibers systems pultruded with epoxy, phenolic and polyester resins as matrix and a mechanic and physic-chemistry characterization was done on the systems by Tensile and Poisson tests, differential sprobe calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transformed infrared spectroscopy (FTIR), following their correspondents standards

SnO2 dense ceramic microwave sintered with low resistivity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chemical and morphological features of dental composite resin: influence of light curing units and immersion media

Aims: The study evaluated the influence of light curing units and immersionmedia on superficial morphology and chemistry of the nanofilled composite resin Supreme XT (3M)through the EDX analysis and SEM evaluation. Light curing units with different power densitiesand mode of application used were XL 3000 (480 mW/cm2), Jet Lite 4000 Plus (1230mW/cm2), andUltralume Led 5 (790 mW/cm2) and immersion media were artificial saliva, Coke1, tea and coffee,totaling 12 experimental groups. Specimens (10 mm 3 2 mm) were immersed in each respectivesolution for 5 min, three times a day, during 60 days and stored in artificial saliva at 378C 6 18Cbetween immersion periods. Topography and chemical analysis was qualitative. Findings: Groupsimmersed in artificial saliva, showed homogeneous degradation of matrix and deposition of calciumat the material surface. Regarding coffee, there was a reasonable chemical degradation with loss ofload particles and deposition of ions. For tea, superficial degradation occurred in specific areaswith deposition of calcium, carbon, potassium and phosphorus. For Coke1, excessive matrix degra-dation and loss of load particles with deposition of calcium, sodium, and potassium. Conclusion:Light curing units did not influence the superficial morphology of composite resin tested, but theimmersion beverages did. Coke1affected material’s surface more than did the other tested drinks.Microsc. Res. Tech. 73:176–181, 2010.

Inspeção de materiais compósitos utilizando ondas acústicas guiadas

Pós-graduação em Engenharia Elétrica - FEIS

Unravelling the reaction mechanism of matrix metalloproteinase 3 using QM/MM calculations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Managing soil carbon for multiple ecosystem benefits positive exemplars: Latin America (Brazil and Argentina)

Agriculture provides food, fibre and energy, which have been the foundation for the development of all societies. Soil carbon plays an important role in providing essential ecosystem services. Historically, these have been viewed in terms of plant nutrient availability only, with agricultural management being driven to obtain maximum benefits of this soil function. However, recently, agricultural systems have been envisioned to provide a more complete set of ecosystem services, in a win-win situation, in addition to the products normally associated with agriculture. The expansion and growth of agricultural production in Brazil and Argentina brought about a significant loss of soil carbon stocks, and consequently the associated ecosystem services, such as flooding and erosion control, water filtration and storage. There are several examples of soil carbon management for multiple benefits in Brazil and Argentina, with new soil management techniques attempting to reverse this trend by increasing soil carbon (C) stocks. One example is zero tillage, which has the advantage of reducing CO2 emissions from the soil and thus preserving or augmenting C stocks. Crop rotations that include cover crops have been shown to sequester significant amounts of C, both in Brazilian subtropical regions as well as in the Argentinean Pampas. Associated benefits of zero tillage and cover crop rotations include flood and erosion control and improved water filtration and storage. Another positive example is the adoption of no-burning harvest in the vast sugarcane area in Brazil, which also contributes to reduced CO2 emissions, leaving crop residues on the soil surface and thus helping the conservation of essential plant nutrients and improving water storage.

Determinação de fósforo em biodiesel utilizando eletrodo quimicamente modificado com nanopartículas de ferro

Once petroleum is na exhaustible source of energy, alternative fuels are having more prominence. A much discussed option for replacing fossil fuels is the use of biofuels derived from oils or fats, especially biodiesel. The biodiesel preparation is through a reaction named transesterification, a reaction of triglycerides with a short chain alcohol with a catalyst, producing a mixture of fatty acid esters and glycerol. According to ANP (National Petroleum Agency) specifications, biodiesel can have contaminants due to the catalyst or oil used on its synthesis, such as phosphorus, wich can damage the catalytic converter and cause significant increase in the particles emission. This project aims to develop na alternative method using chemically modified electrodes with iron nanoparticles for determination of phosphorus in biodiesel. For the formation of the iron nanoparticles film on the surface of a glassy carbon electrode, was used a iron sulfate solution. The film was formed after 10 successive cycles, with a scanning speed of 50 mV s-1 and a potential range of -0,9 to -1,25 V. To reduce possible oxides on the surface and activate the electrode, it has been subjected to a cathodic polarization with a potential of -1,25 V for 15 minutes in a sodium hydroxide solution. In cyclic voltammograms obtained in the study of the speed of scanning, there is an increase in the intensity of the anodic and cathodic current peaks. The cathodic peak current varied linearly with the square root of scan rate, showing that the electrode is controlled by diffusion. After successive additions of phosphate there is a linear variation in the current peak in the concentration range of 1,0 x 10-7 a 1,0 x 10-6 mol L-1. To determine if the concentration of phosphorus in real sample, the method of adding standard was used by adding aliquots of phosphate ions in the solution containing soy biodiesel extracted with ....