Artigos
URI permanente para esta coleçãohttps://repositorio.fei.edu.br/handle/FEI/800
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Artigo 0 Citação(ões) na Scopus Development of highly resistant fibers for use in solid phase micro extraction (SPME)(2010-01-05) RODRIGUES, J. C.; LEITE, D. W.; LANCAS, F. M.The commercially available fibers for solid-phase microextraction (SPME) made of optical fibers are fragile and can be easily broken. Thus, there is a clear need for the development of efficient, simple and highly resistant SPME fibers. This work describes the preparation of highly resistant fibers in which a polymer is coated onto an open tubular fused silica capillary tubing (0.360 mm O.D.) fitted with a stainless steel wire (0.200 mm O.D.) previously inserted and cemented into the capillary tube opening to guarantee higher mechanical resistance. The fiber was coated with 70-μm poly (dimethyl siloxane) (PDMS) and evaluated for the extraction of polycyclic aromatic hydrocarbons.Artigo 23 Citação(ões) na Scopus Composition and screening of antifungal activity against Cladosporium sphaerospermum and Cladosporium cladosporioides of essential oils of leaves and fruits of Piper species(2010-09-05) Andreia de Araújo Morandim Giannetti; PIN, A. R.; PIETRO, N. A. S.; ALECIO, A. C.; KATO, M. J.; YOUNG, C. M.; OLIVEIRA, J. E. DE; FURLAN, M.This study investigated the composition and antifungal activity against Cladosporium sphaerospermum and Cladosporium cladosporioides of essential oils of leaves of Piper cernuum, Piper diospyrifolium, Piper crassinervium, Piper solmsianum and Piper umbelata and fruits of P. cernuum and P. diospyrifolium. The essentials oils were analyzed by GC-MS and submitted of the antifungal activity tests. The essential oils of fruits from P. cernuum and leaves of P. crassinervium and P. solmsianum showed potential antifungal activity against C. sphaerospermum and C. cladosporioides. In addition, this is the first report of the composition of essential oils of fruits of P. cernuum and P. diospyrifolium. © 2010 Academic Journals.Artigo 34 Citação(ões) na Scopus Composition and antifungal activity against candida albicans, candida parapsilosis, candida krusei and cryptococcus neoformans of essential oils from leaves of piper and peperomia species(2010-09-04) Andreia de Araújo Morandim Giannetti; PIN, A. R.; PIETRO, N. A. S.; OLIVEIRA, H. C. DE; MENDES-GIANNINI, M. J. S.; ALECIO, A. C.; KATO, M. J.; OLIVEIRA, J. E. DE; FURLAN, M.This study was addressed to investigate the composition and antifungal activity of essential oils from leaves of Piperaceae species (Piper aduncum, Piper amalago, Piper cernuum, Piper diospyrifolium, Piper crassinervium, Piper gaudichaudianum, Piper solmsianum, Piper regnellii, Piper tuberculatum, Piper umbelata and Peperomia obtusifolia) against Candida albicans, C. parapsilosis, C. krusei and Cryptococcus neoformans. The essential oils from P. aduncum, P. gaudichaudianum and P. solmsianum showed the highest antifungal activity against Cryptococcus neoformans with the MIC of 62.5, 62.5 and 3.9 mg.mL-1, respectively. The oil from P. gaudichaudianum showed activity against C. krusei with MIC of 31.25 mg.mL-1. © 2010 Academic Journals.Artigo 6 Citação(ões) na Scopus Study of salmonella typhimurium mutagenicity assay of (z)-piplartine by the ames test(2011-06-15) Andreia de Araújo Morandim Giannetti; Cotinguiba F.; REGASINI, L. O.; FRIGIERI, M. C.; VARANDA, E. A.; COQUEIRO, A.; KATO, M. J.; BOLZANI, V. S.; FURLAN, M.Phytochemical studies carried out with Piperaceae species have shown great diversity of secondary metabolites among which are several displayed considerable biological activities. The species Piper tuberculatum has been intensively investigated and a series of amides have been described. For instance, (E)-piplartine showed significant cytotoxic activity against tumor cell lines, especially human leukemia cell lines; antifungal activity against Cladosporium species; trypanocidal activity and others. Considering the popular use of P. tuberculatum and the lack of pharmacological studies regarding this plant species, the mutagenic and antimutagenic effect of (Z)-piplartine was evaluated by the Ames test, using the strains TA97a, TA98, TA100 and TA102 of Salmonella typhimurium. No mutagenic activity was observed for this compound. © 2011 Academic Journals.- Optimization of the transesterification reaction in biodiesel production and determination of density and viscosity of biodiesel/diesel blends at several temperatures(2011-05-12) SANTOS, R. O.; COMPRI, T. G.; Andreia de Araújo Morandim Giannetti; Ricardo TorresWaste frying oil has been used to optimize the production of biodiesel. Biodiesel was prepared through sodium ethoxide catalyzed methanolysis from the transesterification of recycled waste frying oil. Optimization of the transesterification reaction for biodiesel production was carried out by means of statistical analyses using ANOVA. The optimum conditions for reaction were the following: a oil-methanol mole ratio of 1:9, temperature of 50 °C, catalyst mass fraction of 0.9 %, and reaction time of 40 min, which enabled a yield of 98.7 % determined by gas chromatography/mass spectrometry (GC/MS) analysis. The density and viscosity of biodiesel/diesel blends have been determined as a function of composition at several temperatures. © 2011 American Chemical Society.
- Effect of lubricant on mechanical and rheological properties of compatibilized PP/sawdust composites(2013-05-15) BETTINI, S. H. P.; JOSEFOVICH, M. P. P. M.; MUNOZ, P. A. R.; LOTTI, C.; MATTOSO, L. H. C.An investigation was performed regarding the effect of compatibilizer and lubricant concentrations on the mechanical and rheological properties of polypropylene/sawdust composites using two-level factorial central composite design. Maleic anhydride grafted PP (PP-g-MA) was used as compatibilizer and the lubricant used was Struktol TPW 113. Composites without these additives were also prepared. Processing was carried out in a co-rotating twin-screw extruder coupled to a Haake rheometer. Mechanical properties were assessed from tensile tests and rheological properties were evaluated by oscillatory measurements and melt flow index (MFI) test. Tensile strength improved with increasing compatibilizer concentration in the composites and reached a maximum value in the absence of lubricant. When both additives were present tensile strength decreased, suggesting a possible interaction between lubricant and compatibilizer, reducing efficiency of the latter. The general trend observed for rheological results was a decrease in complex viscosity, storage modulus and MFI when both additives were present. © 2013 Elsevier Ltd.
- Network flows modeling applied to the natural gas pipeline in Brazil(2013-09-05) VASCONCELOS, C. D.; LOURENÇO, S. R.; GRACIAS, A. C.; CASSIANO, D. A.The use of natural gas during the last decades has been growing, and this trend will continue until 2030, according to the Brazilian energy plan issued by Ministry of Mines and Energy (2007a). However, the capacity of transportation is one of the important elements of the supply chain in response to the distribution market. In this context, the present study aims at identifying, in a regional and integrated way, the transportation capacity of the natural gas pipeline network. Therefore, a database and a mathematical model were developed to calculate the network maximum flow in order to enable analysis of the natural gas flow in the national network. The complex natural gas flow and the forecast of increasing demand justify the study of this issue, and the development of tools to help analyze the feasibility of implanting the decennial energy plan. The mathematical model used considers a linear programming to calculate the flows in the network. Data were collected about the operating companies, existing pipelines, handling capacity, historical flow and demand forecast. The delivery capacity in the consumer markets is also analyzed by means of economic and population index compared to the 2020 target. The results show a maximum nominal capacity of 213MMm3 per day at reception points, and 227MMm3 per day at delivery points. Idleness was found in the networks of the Northeast and Espírito Santo area (14% and 6.1%), and lack of capacity was found in the Southeast and South networks (11.6% and 9%), compared with the economic index of consumer centers near the networks. In comparison to the current flow, 75% of idleness was found. Idleness was identified in the networks of the Northeast and Espírito Santo areas (55% and 68%), and lack of capacity was identified in the Southeast and South networks (7% and 74%), in comparison to the 2020 target. In the analysis of the 2020 target, compared to the capacity in the metropolitan areas, lack of capacity was found in the metropolitan areas of Sao Paulo, Belo Horizonte, Fortaleza and South area (68%, 5%, 59% and 74%) and idleness was found in the areas of Vitória, Recife, Rio de Janeiro, Maceió, Aracaju, Salvador and Natal (85%, 72%, 40%, 93%, 8%, 58% and 17%). © 2013 Elsevier B.V.
- An overview of heavy oil properties and its recovery and transportation methods(2014-07-01) SANTOS, R. G.; LOH, W.; BANNWART, A. C.; TREVISAN, O. V.© 2014, Assoc. Brasiliera de Eng. Quimica / Braz. Soc. Chem. Eng. All rights reserved.Unconventional oils - mainly heavy oils, extra heavy oils and bitumens - represent a significant share of the total oil world reserves. Oil companies have expressed interest in unconventional oil as alternative resources for the energy supply. These resources are composed usually of viscous oils and, for this reason, their use requires additional efforts to guarantee the viability of the oil recovery from the reservoir and its subsequent transportation to production wells and to ports and refineries. This review describes the main properties of high-viscosity crude oils, as well as compares traditional and emergent methods for their recovery and transportation. The main characteristics of viscous oils are discussed to highlight the oil properties that affect their flowability in the processes of recovery and pipeline transportation. Chemical composition is the starting point for the oil characterization and it has major impact on other properties, including key properties for their dynamics, such as density and viscosity. Next, enhanced oil recovery (EOR) methods are presented, followed by a discussion about pipeline and transportation methods. In addition, the main challenges to achieve viable recovery and transportation of unconventional oils are compared for the different alternatives proposed. The work is especially focused on the heavy oils, while other hydrocarbon solid sources, such as oil sands and shale oil, are outside of the scope of this review.
- Copper nanoparticles synthesized by thermal decomposition in liquid phase: the influence of capping ligands on the synthesis and bactericidal activity(2014) EFFENBERGER, F. B.; SULCA, M. A.; MACHINI, M. T.; COUTO, R. A.; KIYOHARA. P. K.; MACHADO. G.; ROSSI, L. M.© 2014, Springer Science+Business Media Dordrecht.We explored here the synthesis of copper nanoparticles (CuNPs) by thermal decomposition of copper(II) acetate in diphenyl ether in the presence of different capping ligands. To look for any specific role in thermal decomposition, we performed reactions in the presence of oleic acid, oleylamine, and 1,2-octanediol, or in the presence of different combinations of these capping ligands, or in the absence of them. The CuNPs obtained in the presence of oleic acid and oleylamine (in the presence or absence of 1,2-octanediol) were stabilized as Cu(0) NPs, and the “naked” NPs prepared in solvent only easily oxidized to CuO. Therefore, both oleic acid and oleylamine can act as capping ligands to prepare air-stable Cu(0) NPs. The 1,2-alkyldiol is not necessary for metal reduction during the synthesis, but its presence improves size and morphology control. The presence of capping ligands significantly reduced the bactericidal activity exhibited by the Cu NPs against the gram-negative bacteria Escherichia coli.
- Thermal analysis and combustion kinetic of heavy oils and their asphaltene and maltene fractions using accelerating rate calorimetry(2014-11-05) Ronaldo Santos; VIDAL, V. J. A.; TREVISAN. O. V.© 2014 American Chemical Society.This work presents an experimental study on the thermal and kinetic parameters of the oxidation reaction of heavy crude oils to support the in-situ combustion oil recovery technique. An accelerated rate calorimeter was used to investigate the thermal behavior of two Brazilian heavy oils in an open system under constant pressure and continuous heating to 550 °C. The goal was to identify and characterize several oxidation regions and to obtain the activation energy and reaction order. The temperature-time curves showed three clearly distinct regions. During the heating, autoignition was found to have started at 180-220 °C. Then, the reaction curves exhibit a strong exothermic behavior up to 250-350 °C, which represents the low-temperature oxidation. Asphaltenes were found to play a crucial role in the kinetic behavior of the crude oils. The results show that oxygen-addition reactions are dominant from 200 to 300 °C and that bond-scission reactions are dominant above 350 °C. Although the presence of sand and clay improves the contact between the oil and oxygen and accelerates both of these reactions, it has a greater impact on the oxygen-addition reactions. The results provide helpful data for the screening of crude oils as candidates for recovery by in-situ combustion.