Abstract in English:This work presents results of the preparation and characterization of small unilamellar liposomes for entrapping allergenic proteins extracted from the biomass of Dreschlera (Helminthosporium) monoceras cultivated by solid fermentation. Protein was entrapped by the dehydration-rehydration method, using lyophilization of preformed liposomes in order to prevent their degradation The reconstitution of lyophilized liposomes by hydration, their capacity for entrapping allergenic proteins and their stability in plasma were analyzed. Liposomes were reconstituted in size by including trehalose sugar in the formulation. The protection of the liposomal membrane by trehalose was characterized by differential scanning calorimetry and X-ray diffraction. The reconstituted membrane had an osmotic behavior similar to that of nondehydrated ones. Allergenic proteins ranging in molecular weight from 14 to 170 kDa were entrapped in the lipid matrix with an efficiency of approximately 80%. These results are promising for producing liposomes by entrapping allergenic proteins from mold extracts, which can be useful for allergy therapy.
Abstract in English:Partial hydrolysis of whey proteins by enzymes immobilized on an inert support can either change or evidence functional properties of the produced peptides, thereby increasing their applications. The hydrolysis of sweet cheese whey proteins by alcalase, which is multipoint-immobilized on agarose gel, is studied here. A Michaelis-Menten model that takes into account competitive inhibition by the product was fitted to experimental data. The influence of pH on the kinetic parameters in the range 6.0 to 11.0 was assessed, at 50ºC. Initial reaction-rate assays in a pHstat at different concentrations of substrate were used to estimate kinetic and Michaelis-Menten parameters, k and K M. Experimental data from long-term batch assays were used to quantify the inhibition parameter, K I. The fitting of the model to the experimental data was accurate in the entire pH range.
Abstract in English:The methylotrophic yeast Pichia pastoris was used to produce the recombinant Pisum sativum defensin (rPsd1), a small peptide from pea seeds that has a high level of antifungal activity. The plasmid rPsd1/pPIC9 was integrated into the yeast genome and methanol was used to induce expression and secretion of the recombinant Psd1, at 30º C in a fed-batch mode. The effects of different pH conditions and process scale-up were evaluated using a Monod-type model where dissolved oxygen was considered the limiting substrate. Parameter estimation showed that the process could be improved by expressing rPsd1 in a 1000 mL bioreactor at pH 4. Structural and functional analyses revealed that the recombinant Psd1 is very similar to the native one.
Abstract in English:Due to the role of interleukin-2 (IL-2) in the mediation of immune response, this cytokine has been used in the treatment of some types of cancer and infectious diseases. However, relatively high levels of this cytokine are required to achieve significant activity. The aim of this work was to study a culture medium composition designed to increase the production of IL-2 by suspended murine EL-4 cells. The cultivations were carried out aiming at producing IL-2 in stirred bioreactors. The effects of concentration of glutamine, phorbol-12-myristate-13-acetate (PMA), concanavalin A (Con A), Pluronic F68, and fetal calf serum (FCS) on cell viability and IL-2 production were evaluated. PMA alone was more efficient in IL-2 production than it was in association with Con A. The maximum IL-2 production was around 162 ng/mL with 856 ng/mL PMA and 1.45% (v/v) FCS.
Abstract in English:A bench-scale, continuous vortex flow reactor (VFR), with a radius ratio, h, equal to 0.48 and an aspect ratio, G, equal to 11.19 was studied. This reactor may be used in the enzymatic hydrolysis of polypeptides obtained from sweet cheese whey with enzymes immobilized on agarose gel. Operational conditions were 2410 < Re q < 11793 and 30-min residence time for glycerol-water, 14% w/w, 27ºC (Re ax = 1.1) and for water, 38ºC (Re ax = 1.5). Residence time distributions (RTDs) were obtained after pulse injections of different tracers (including dyed solid particles). Mass transfer coefficients of a lumped-parameter model of the reactor were estimated from these data. Model fitting to experimental data was accurate. Working conditions were selected so that transport properties of the fluids would be similar to the ones in the actual process at the final stages of whey hydrolysis.
Abstract in English:Cell growth and retamycin production in Streptomyces olindensis So20 were studied at different dissolved oxygen levels during fermentation. The profiles for cell growth and retamycin production in an experiment with dissolved oxygen control at 5% air saturation during production were similar to those in an experiment without dissolved oxygen control. However, despite slower cell growth, a twofold increase in the final retamycin concentration was achieved when dissolved oxygen was controlled at 100% during the growth phase, compared to a base experiment (no DO control). Therefore, the results revealed that retamycin production was dependent on dissolved oxygen concentration during the growth phase, even with sufficient oxygen. On the other hand, a large oxygen supply during the production phase did not contribute to an improvement in retamycin production.
Abstract in English:This work studied the influence of calcination conditions on basic properties and catalytic performance of Mg,Al-mixed oxides derived from a hydrotalcite sample (Al/(Al+Mg)=0.20). Various heating rates, calcination atmospheres and lengths of calcination at 723K were evaluated. TPD of CO2 and retroaldolization of diacetone alcohol (DAA) were used to determine the basic properties of the mixed oxides. The basic site density determined by TPD of CO2 showed a better correlation with catalytic activity for acetone/citral aldol condensation than the relative basicity obtained from retroaldolization of DAA. Calcination atmosphere was the parameter that influenced most the basic and the catalytic properties of the Mg,Al-mixed oxides, with calcination under dry air being the best choice.
Abstract in English:The effect of the addition of Mg and Ca to Ni/ a-Al2O3 catalysts was investigatedstudied, aiming to detail the promotion mechanismaddress their role as promoters in the steam reforming reaction. Temperature- programmed reduction and H2 and CO temperature-programmed desorption experiments indicated that Mg interacts with the metallic phase. Mg-promoted catalysts showed a greater difficulty for Ni precursors reduction besides different probe molecules (H2 and CO) adsorbed states. In the conversion of cyclohexane, Mg inhibited the formation of hydrogenolysis products. Nonetheless, the presence of Ca did not influence the metallic phase.
Abstract in English:In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose of producing aromatic aldehydes in continuous regime, a three-phase fluidized reactor was built, and it was operated using atmospheric air as the oxidizer. The best yield in aromatic aldehydes was of 12%. The experimental results were compatible with those values obtained by the pseudo-heterogeneous axial dispersion model (PHADM) applied to the liquid phase.
Abstract in English:An experimental study was carried out aiming to evaluate the performance of a three-phase fluidized bed bioreactor (FBBR) used to treat milk wastewater. In this study three different concentrations of milk wastewater substrate (462, 825 and 1473 mg O2/L) were tested. Using the same number of support particles, the results demonstrate that the average efficiency of COD removal decreased as the concentration of organic load in the substrate was increased. The growth of microorganism in the FBBR was followed by a count of viable cells in both liquid phase and the biofilms attached to the support. An increased number of viable cells were observed inside the reactor when it was used to degrade higher organic loads, with most of the cells on the support. The higher concentration of active biomass was responsible for achieving a relatively high absolute degradation of the wastewater containing the high organic load.
Abstract in English:The aim of this work was to develop a mathematical model for a continuously operating flotation tank to provide the scale-up and optimization of the separation system. The fluid dynamic of the tank was assumed to be a perfect mixture and the flotation kinetics to be a first-order reaction, as suggested by the batch operation. The experiments were carried out in a continuously operating 60 L tank, used in the treatment of a synthetic dairy waste at its isoelectric point. A mathematical model that describes the behavior of a continuously operating flotation tank used in the treatment of a synthetic dairy waste at its isoelectric point is not only proposed, but also validated with experimental data.
Abstract in English:Recently, increasing concern about pollution of groundwater by organic chemicals has led to research on the use of various adsorbents. This study addressed the sorption of phenol and organic compounds by two organoclays and a coal/mineral complex (ARO). The organoclays used were a bentonite from Brazil (SVC) and Wyoming bentonite (SWy) with quaternary ammonium salt (ABDMA). Swelling capacity of the sorbents in toluene, diesel, gas, Varsol and kerosene were measured. Absorption of organic compounds served as an ASTM D 281-95 base, which resulted in the following order for ABDMA-SVC: gas > toluene > kerosene > diesel > Varsol. ABDMA-SWy absorbed in the following order: gas > toluene > Varsol > diesel > kerosene. ARO absorbed: gas > toluene >diesel > Varsol > kerosene. Sorption of phenol followed the order of ABDMA-SVC > ABDMA-SWy > ARO. The adsorption data show that the materials prepared were effective in sorbing phenol, and that the Brazilian clay was the most efficient of the three materials.
Abstract in English:Stearic acid was incorporated into whey protein through emulsification to produce films. Whey protein films were prepared by dispersing 6.5% protein in distilled water. Glycerol was the plasticizer agent. Stearic acid was added at different levels (0.0 to 1.0%) and the films were analyzed at different pHs (5.0, 6.0, 7.0 and 9.0). The emulsion films were evaluated for mechanical properties, water vapor permeability and protein solubility. It was observed that water vapor permeability and protein solubility values for the film decreased with increasing fatty acid content in the film, but the mechanical properties also decreased.
Abstract in English:Polymeric materials are increasingly replacing metallic materials as a result of their properties. In this work a composite of phenolic resin and sugar cane pulp was developed. The sugar cane pulp has been previously alkalinised, dried, and milled and the particles had been classified in a range of grain sizes. Experimental assays were performed, varying the proportion of the resin and the reinforcement and the size of the cane pulp fibre, keeping the pressure and moulding temperature constant. These composites were characterised according to physical and chemical properties, through test bodies produced in moulds according to ASTM standards. The experiments performed showed that the use of sugar cane pulp as reinforcement in polymeric composites represents an option for reducing costs in industrial applications, thus suggesting a significant industrial applicability of the product.
Abstract in English:The objective of this research was to develop and characterize composite biofilms produced using wheat gluten and cellulose acetate phthalate. Biofilms act as barriers to moisture and oxygen diffusion through the film. The films were prepared with different thicknesses and component concentrations and were analyzed for water vapor and oxygen permeabilities, water and acid solubilities and mechanical properties. Results showed that the mixture improved film characteristics more than each of the individual components alone. The 1:1 mixture had properties of better permeability to water and oxygen. The composite films were completely soluble in water and acid, with the exception of the film with the highest gluten concentration, which was 50% soluble in water and acid. An increase in gluten concentration in the composite films resulted in a decrease in tensile strength. There was no significant difference in elongation at break between the composite films. No difference in thickness was detected either. Results showed that the mixture improved the characteristics more than of the individual components alone.
Abstract in English:Recently, thermoanalytic methods have frequently been used in the characterization of oils and fats. In this work, thermoanalytic and kinetic parameters of sunflower oils, with and without antioxidants, were evaluated using thermogravimetry / derivative thermogravimetry and differential scanning calorimetry. The thermogravimetric profiles for the sunflower oils had similar characteristics, showing a level stretch indicative of stability up to about 200ºC. Thermal decomposition of these oils occurred in three stages, related to the decomposition of polyunsaturated, monounsaturated and saturated fatty acids, respectively. DSC curves show two events that characterize the polymerization and decomposition of triglycerides. The heat capacities of the sunflower oils, obtained by DSC, showed a good correlation and were dependent on the composition of fatty acids. The kinetic parameters, obtained by non isothermal thermogravimetry by the Coats and Redfern, Madhusudanan, Horowitz and Metzger and Van Krevelen methods, were dependent on the antioxidant used. Increasing the frying time produced a decrease in the onset of thermal decomposition temperature in the sunflower oils analyzed.
Abstract in English:Performance of a wire-plate electrostatic precipitator in the removal of particles with a wide particle size distribution was evaluated. The experimental rig utilized consisted of a set of three precipitators whose dimensions could be varied. It was observed that precipitator performance increased with an increase in the gap between the collecting plates, which resulted in a substantial increase in energy consumption per volume of cleaned gas. The grade efficiency predicted by correlations from the literature did not match the experimental measurements, and a new correlation is proposed.
Abstract in English:Although it is still used very little by industry, the process of essential oil extraction from vegetable matrices with supercritical CO2 is regarded as a potentially viable technique. The operation of separating the extract from the solvent is carried out by reducing the pressure in the system. Separation by membranes is an alternative that offers lower energy consumption and easier operation than traditional methods of separation. Combining the processes essential oil extraction with supercritical CO2 and separation by membranes permits the separation of solvent and oil without the need for large variations in extraction conditions. This results in a large energy savings in the case of solvent repressurisation and reuse. In this study, the effectiveness of reverse osmosis membranes in separating lemongrass essential oil from mixtures with supercritical CO2 was tested. The effects of feed oil concentration and transmembrane pressure on CO2 permeate flux and oil retention were studied for three membrane models.
Abstract in English:This work is concerned with the coupled estimation of the heat generated by the reaction (Qr) and the overall heat transfer parameter (UA) during the terpolymerization of styrene, butyl acrylate and methyl methacrylate from temperature measurements and the reactor heat balance. By making specific assumptions about the dynamics of the evolution of UA and Q R, we propose a cascade of observers to successively estimate these two parameters without the need for additional measurements of on-line samples. One further aspect of our approach is that only the energy balance around the reactor was employed. It means that the flow rate of the cooling jacket fluid was not required.
Abstract in English:In this work an enzymatic lactose biosensor composed of the immobilized enzymes b-galactosidase and glucose oxidase was developed. Oxygen consumption during the reaction catalyzed by these enzymes was detected. The biosensor was integrated into an FIA (flow injection analysis) system that allows measurement of lactose on-line in less than three minutes. This biosensor was used to monitor lactose concentration during the production of b-galactosidase by the yeast Kluyveromyces marxianus from cheese whey. The sensor showed good stability after four months and after almost 7000 measurements had been performed. The analytical curve was linear in the range of lactose concentration from 1 to 30 g/L.
Abstract in English:Unsaturated, nitrogenated and sulfured compounds may reach undesirable levels in lubricant base oils, requiring hydrotreatment (HDT) at high temperatures and pressures. HDT processes are well known for their high capital and operational costs due to the use of hydrogen, compressors and multistage heterogeneous reactors. Process costs are thus highly dependent on the applied conditions. An oversized process entails unnecessary costs and capital investment. On the other hand, mild reaction conditions lead to unspecified products. This work analyzes the process using a compositional modeling and a kinetic framework developed previously (Barbosa et al., 2002) for the HDT of lubricant base oils. The industrial reactor is rigorously modeled on an adiabatic and multistage configuration. For the remaining equipment in the flowsheet, we adopt shortcut models for compressors and exchangers. The process is then optimized in terms of its variables subject to product specification constraints.
Abstract in English:The objective of this work was to study the coating of microcrystalline cellulose with a polymeric suspension in a fluidized bed. The coating operation was carried out using a fluidized bed with top spraying by a double-fluid nozzle. The fluidized bed consists of a cylindrical column made of plexiglass with a height of 0.6 m and an inner diameter of 0.14 m. The polymeric coating suspension was formulated using Eudragit® as the basic component. As the quality of the coating product is greatly affected by the spraying characteristics, the influence of the flow rate of the coating suspension and the moisture content of the particles on the agglomeration index and efficiency of the process of coating microcrystalline cellulose was analyzed.
Abstract in English:The Venturi scrubber is a device which uses liquid in the form of droplets to efficiently remove fine particulate matter from gaseous streams. Droplet size is of fundamental importance for the scrubber performance. In the present experimental study, a laser diffraction technique was used in order to measure droplet size in situ in a Venturi scrubber with a rectangular cross section. Droplet size distribution was measured as a function of gas velocity (58.3 to 74.9 m/s), liquid-to-gas ratio (0.07 to 0.27 l/m³), and distance from liquid injection point (64 to 173 mm). It was found that all these variables significantly affect droplet size. The results were compared with the predictions from correlations found in the literature.
Abstract in English:Aiming at simulating air-heating systems, two algorithms were developed for the calculation of finned elliptical-tube heat exchangers, whose basic difference lies in the kind of hot fluid employed: saturated steam or hot liquid. In both cases, a crossflow unit, in which the cold fluid is mixed and always flows on the shell side, is considered. The hot fluid may exhibit multiple passes in the tubes and is assumed unmixed, except for the region between the passes. A comparison between calculated results and operating data on industrial exchangers indicated the adequacy of the algorithms developed. The codes were then introduced into the ASPEN Plus shell, enabling simulation of the steady-state operation of the whole drying-air heating system of a powdered milk plant. Moreover, a sensitivity analysis of this system was conducted for one of its operating parameters and the existence of an optimal value for this variable was clearly shown.