Engenharia Química

URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/25

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Possible indirect measurement of diffusion coefficient from migration kinetic essay of food packaging
(2008-09-10) MANZOLI, J. E.; LEMOS, C.; PANZARINI, L. C. G. A.; FÉLIX, J. S.; MONTEIRO, M.
Diffusion coefficient is an important quantity that affects any migration process on food or nutritional systems. Special care has to be done to migration of undesirable substances from packaging into foods, if the diffusion is the only process involved in mass transfer. The Fick's equation resolution permits to describe the kinetic of migration from polymer packaging into food or simulant, once it was given the correct contour and initial conditions. Another important quantity is the partition coefficient, which quantifies the relation between the final or equilibrium concentrations in polymer and that in the food or simulant. Here it is proposed a simple procedure, based on numerical resolution of the Fick's equation, where the diffusion coefficient could indirectly be measured, if the kinetic of migration had been measured and the partition coefficient is known.
Use of hydrodynamic cavitation as an alternative for biodiesel production
(2009-08-30) SANTOS, S. L. DOS; FERREIRA, M. S.; Maristhela Passoni de Araújo Marin; Luis Novazzi
© 2009 by ABCM.Biodiesel is known as an alternative to conventional petrodiesel because of its renewability and better combustion performance, in addition to reducing emissions, harmful to the environment. Biodiesel production consists on the transesterification of triglycerides with an alcohol and the reaction is affected by the alcohol type, temperature, molar ratio of alcohol to oil and catalyst type and amount. Since this reaction is a heterogeneous one, reagent mixing is also of crucial importance and traditionally the blending is carried out by using mechanical mixers. In this work a different approach is proposed, where the mixing is induced by hydrodynamic cavitation provoked by an orifice plate connected to the suction of a centrifugal pump. Biodiesel production was carried out at 45°C with a 1:8 molar ratio of soybean oil to ethanol. It was observed that the method assisted by hydrodynamic cavitation promotes the enhancement of biodiesel yield in comparison to the conventional method that uses mechanical stirring. In comparative tests carried out from 0 to 40 minutes, the hydrodynamic cavitation always showed conversion rates larger than the mechanical agitation. Although specific energy consumption in biodiesel production is slightly higher for hydrodynamic cavitation when compared to conventional mechanical mixing, it was observed that in the alternative approach the equipment employed is simple and has a low acquisition cost, showing that it has a great potential to be scaled up and used in industrial processes.
Intraspecific variability of dihydrochalcone, chromenes and benzoic acid derivatives in leaves of Piper aduncum L. (Piperaceae)
(2009-05-18) Andreia de Araújo Morandim Giannetti; KATO, M. J.; CAVALHEIRO, A. J.; FURLAN, M.
Chemical analysis carried out in leaves of 18 specimens of Piper aduncum L. (Piperaceae) occurring at Ripasa Reserve, Araraquara, SP, Brazil indicated two distinct populations when investigated over a period of 14 months (January 2000 to February 2001) and then submitted to cluster analysis. The two groups were characterized by accumulation of prenylated benzoic acids, chromenes and dihydrochalcone, respectively. A total of seven compounds were identified by HPLC analysis and compared with standards including two prenylated benzoic acid [aduncumene (1) and 3-(3′-7′-dimethyl-2′-6′-octadienyl)- 4-methoxy-benzoic acid (5)], four chromenes [methyl 2,2-dimethyl-8-(3′- methyl-2′-butenyl)-2H-1-chromene-6-carboxylate (4), methyl 2,2-dimethyl-2H-1-chromene-6-carboxylate (2b), methyl 8-hydroxy-2,2-dimethyl-2H- 1-chromene-6-carboxylate (3) and 2,2-dimethyl-2H-1-chromene-6-carboxylic acid (2a)] and one dihydrochalcone [2′,6′-dihydroxy-4′-methoxy- dihydrochalcone (6)]. © 2009 Academic Journals.
Multivariable control of a heat exchanger with bypasses
(2009-07-15) Delatore, F.; DA CRUZ, J. J.; Fabrizio Leonardi; Luis Novazzi
A myriad of different multivariable control techniques, ranging from the simplest isolated PID controllers to the most sophisticated model predictive controls, are presented in the literature and applied to chemical plants. This work intends to present an intermediate control solution between the simplest and the most complex control design, with a relative simplicity, in combination with a superior performance when compared to traditional PID controllers. The proposed strategy, based on a Linear Quadratic Regulator (LQR), was applied to a heat exchanger with bypasses, which is a typical equipment in industries' processes. Even though the LQR is relatively straightforward to design, with a simple tuning procedure, some simulations' results demonstrated that the proposed approach leaded to a reasonable control performance, i.e., process variables became almost totally decoupled, no offset was observed and the output responses presented an small time constant.
Calorimetric measurement of the interface energy of pure and calcium doped magnesium oxide
(2009-10-29) CASTRO, R.; Ricardo Torres; GOUVEA, D.
Interface energetics is of key importance in understanding the evolution of nanoparticles during sintering. During this process, two types of interfaces control the driving forces: the surface and the grain boundary. The knowledge of their energies is therefore of major importance to obtain reliable sintered bodies. The objective of this work was to present a quantitative relationship between the grain boundary energy and the surface energy of MgO and Ca-doped MgO nanoparticles to provide data to better understand the sintering behavior of this system, in particular delineating the thermodynamic basis of using Ca as sintering add. Using a novel and convenient calorimetric procedure, the ratio between the grain boundary energy and the surface energy was determined to be 1.1 for pure MgO and 0.7 for Ca-doped MgO. Based on these, the grain boundary energy of pure MgO and Ca-doped MgO were estimated to be 1.2 J.m-2 and 0.4 J.m-2, respectively. The grain boundary energy decrease caused by calcium doping was attributed to its interface segregation and influenced the sintering behavior by changing the equilibrium dihedral angle in addition to diffusion parameters.
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.
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.
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.
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.
DMLM III device development for enzymes biochemical reactions in microgravity
(2011-05-22) LA NEVE, A.; BELLODI, M.; MELO, M. A. A.; FERREIRA, M.; PEREIRA, A. N.; LUCARINI, A. C.
The goal of this experiment was to investigate the invertase enzyme kinetics in microgravity to better understand the mechanism action inside and outside biological cells. To do this DMLM 111 device was developed, which is responsible for mixing liquids in microgravity. It consists of a mechanical part, with ten sets of reaction systems, and embedded electronics. Each reaction system consists of three chambers, for the enzyme, the substrate and the reaction inhibitor, and two valves to keep the liquids separated. When microgravity signal is triggered, enzyme and substrate are mixed to start the biochemical reaction. After five minutes the reaction is interrupted with the inhibitor. This experiment was embedded on a VSB-30 Brazilian sounding rocket, and payload remained in microgravity for approximately six minutes. Biochemical analyses of the samples are under way, and the results will be compared with the data obtained on earth, under similar conditions.

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