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Harada Layse H. P. da Costa Aline C. Filho Rubens Maciel 《Applied biochemistry and biotechnology》2002,98(1-9):1009-1023
The objective of this work was to develop a model for an extractive ethanol fermentation in a simple and rapid way. This model
must be sufficiently reliable to be used for posterior optimization and control studies. A hybrid neural model was developed,
combining mass and energy balances with neural networks, which describe the process kinetics. To determine the best model,
two structures of neural networks were compared: the functional link networks and the feedforward neural networks. The two
structures are shown to describe well the process kinetics, and the advantages of using the functional link networks are discussed. 相似文献
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Nivea de Lima Da Silva Maria Regina Wolf Maciel César Benedito Batistella Rubens Maciel Filho 《Applied biochemistry and biotechnology》2006,130(1-3):405-414
The transesterification of castor oil with ethanol in the presence of sodium ethoxide as catalyst is an exceptional option for the Brazilian biodiesel production, because the castor nut is quite available in the country. Chemically, its oil contains about 90% of ricinoleic acid that gives to the oil some beneficial characteristics such as its alcohol solubility at 30°C. The transesterification variables studied in this work were reaction temperature, catalyst concentration and alcohol oil molar ratio. Through a star configuration experimental design with central points, this study shows that it is possible to achieve the same conversion of esters carrying out the transesterification reaction with a smaller alcohol quantity, and a new methodology was developed to obtain high purity biodiesel. 相似文献
66.
Patrícia Andrade Neves Paulo Alves de Lima Ferreira Márcia Caruso Bícego Rubens Cesar Lopes Figueira 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):407-414
Guajará Bay is an integral part of the Amazon Estuary system, and functions as the main receiver of urban and industrial wastes from the city of Belém, capital city of PA State (N Brazil). There is a lack of knowledge regarding quantitative measures of sedimentation, such as sedimentation rates, in the literature for this area of the Amazon Estuary. This study aimed the evaluation of recent (time range of 100 years) sedimentation rates in three sediment profiles collected in the coastal system of Guajará Bay with a radioanalytical approach of unsupported 210Pb and 137Cs modeling. The mean sedimentation rates for the cores obtained were 0.85 ± 0.12 cm year?1 for Anadim core, 1.02 ± 0.17 cm year?1 for Outeiro core and 0.53 ± 0.04 cm year?1 for Tucunduba core. With the use of three models of sedimentation rate models, it was observed that Anadim and Outeiro core presented constant sedimentation rates for the evaluated time range, but Tucunduba did not. This difference in sedimentation rates was probably due to their different sampling locations that present diverse hydrodynamic regime, with deposition of fine sediments in the upper area of the bay and stronger fluvial currents in the southernmost region. 相似文献
67.
Carlos L. P. Carone Geraldo L. Crossetti Nara R. S. Basso Álvaro G. O. Moraes João H. Z. dos Santos Rubens Bisatto Griselda B. Galland 《Journal of polymer science. Part A, Polymer chemistry》2007,45(22):5199-5208
The catalyst DADNi(NCS)2 (DAD = (ArN?C(Me)? C(Me)?ArN); Ar = 2,6‐C6H3), activated by methylaluminoxane, was tested in ethylene polymerization at temperatures above 25 °C and variable Al/Ni ratio. The system was shown to be active even at 80 °C and when supported on silica. However, catalyst activity decreased. The catalyst system was also tested in ethylene and 10‐undecen‐1‐ol copolymerization at different ethylene pressures. The best activities were obtained at low polar monomer concentration (0.017 mol/L), using triisopropylaluminum (Al‐i‐Pr3) to protect the polar monomer. The incorporation of the comonomer increased with the increase of polar monomer concentration. According to 13C NMR analyses, all the resulting polyethylenes were highly branched and the polar monomer incorporation decreased as ethylene pressure increased. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5199–5208, 2007 相似文献
68.
Gijs Ramakers Maarten Rubens Alexander Krivcov Hildegard Mbius Vanessa Trouillet Alexander Welle Tanja Junkers 《Journal of polymer science. Part A, Polymer chemistry》2019,57(18):2002-2007
The UV‐induced and catalyst‐free photoiniferter surface grafting using xanthate RAFT agents is studied. First, a novel silane containing a xanthate RAFT agent moiety is synthesized and successfully grafted onto a silicon wafer as confirmed by secondary ion mass spectrometry (SIMS). Next, using only methyl acrylate, solvent and UV light (365 nm) polymer brushes are grafted rapidly from the surface with film thicknesses up to 25 nm reached within half an hour. The obtained polymer films are thoroughly analyzed by X‐ray photoelectron spectroscopy (XPS), ToF‐SIMS, and AFM. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2002–2007 相似文献
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Fregolente LV Batistella CB Filho RM Wolf Maciel MR 《Applied biochemistry and biotechnology》2006,131(1-3):680-693
Monoglycerides (MG) are emulsifiers widely used in food and pharmaceutical industries. Current industrial processes for MG production consist of the interesterification of triglycerides with glycerol (GL), in the presence of inorganic catalysts at high temperatures (>200 degrees C). This reaction is known as glycerolysis and produces a mixture of approx 50% of MG. This level of concentration is suitable for many applications, although, for some specific uses like margarine, shortening, icing, and cream filling, require distilled MGs, which are purified MG (min. 90%) obtained by the molecular distillation process. Therefore, in this work, a 2(3) factorial design was employed to evaluate the effects of reaction parameters in the MG content after the interesterification reaction of refined soybean oil with GL in the presence of sodium hydroxide as catalyst. After that, the MG content in the reaction product was enhanced through the molecular distillation process in order to obtain distilled MG. 相似文献