Modelling And Adaptive Control Of L-asparaginase Reactor

Tubular reactors are non-linear and time-varying distributed parameter systems with complex dynamics so that it is difficult to have high performance and safe operation when conventional classic control procedures are employed. In this work, an adaptive controller based on state space approach is developed and tested for the control of a biochemical reactor, using L-Asparaginase attached on the internal open nylon tube. It is shown that the control algorithm is adequate to maintain the system in a specified operational conditions even when significant disturbances takes place as well as the set-point changes. Furthermore, an adequated operational strategy and a good control scheme improved the stability of the system and make the L-asparaginase reactor to be an efficient method in the treatment of leukaemia.18SUPPLS693S69

A spreadsheet for calculation of ingredients for standardization of requeijão cremoso Planilha eletrônica para cálculos de ingredientes visando à padronização de requeijão cremoso

The standardization of requeijão cheese quality characteristics is a processing stage which is directly influenced by the chemical composition of the raw material. Fat and water concentrations are the main factors that cause variation in quality properties of the requeijão and, when not thoroughly controlled, may cause a lack in standardization of the food. Calculations of ingredients for effective standardization must be made in relation to the final product through of iterative calculations, which makes the manual process unfeasible. Thus, the objective of the present study was to develop a spreadsheet for ingredient calculation, with restrictions being the different concentrations of fat and water in order to standardize the final products. The spreadsheet was developed using the Excel 2007® Solver function, with just four input data: quantity of mass, water and fat content of the mass and fat content of the cream. The optimal solution was that which maximizes the amount of final product while meeting the stipulated constraints of fat and water. Results obtained with the spreadsheet were validated by processing the requeijão cheeses and comparison of the theoretical and practical parameters using the t-test. There was no significant difference between fat and water contents (p>0.10) estimated and verified in practice. Therefore, the use of the spreadsheet proved to be efficient for standardization of requeijão formulations.A padronização das características de qualidade do requeijão é uma etapa do processamento, a qual é diretamente influenciada pela composição química da matéria-prima. Os teores de gordura e água são os principais fatores que acarretam variação nas propriedades de qualidade do requeijão e, quando não controlados minuciosamente, causam despadronização do alimento. Os cálculos de ingredientes para efetiva padronização devem ser realizados em relação ao produto final, por meio de cálculos iterativos, o que inviabiliza o processo manual. Nesse contexto, o presente trabalho teve por objetivo desenvolver uma planilha eletrônica para cálculo de ingredientes, tendo como restrições diferentes teores de gordura e água, visando à padronização dos produtos. A planilha foi desenvolvida utilizando-se o suplemento Solver do Excel2007®, sendo que os únicos parâmetros de entrada após a implementação da planilha foram: quantidade de massa, teor de gordura e de água na massa e teor de gordura do creme. A solução ótima foi a maximização da quantidade do produto final que satisfizesse as restrições dos teores de gordura e água estipulados. Os resultados obtidos pela planilha foram validados por meio do processamento dos requeijões e da comparação dos parâmetros teóricos e práticos utilizando-se o teste t. Não houve diferença significativa entre os teores de gordura e de água (p>0,10) estimados e verificados na prática. Portanto, a utilização da planilha eletrônica se apresenta eficiente para padronização de formulações de requeijão cremoso

A spreadsheet for calculation of ingredients for standardization of requeijão cremoso

The standardization of requeijão cheese quality characteristics is a processing stage which is directly influenced by the chemical composition of the raw material. Fat and water concentrations are the main factors that cause variation in quality properties of the requeijão and, when not thoroughly controlled, may cause a lack in standardization of the food. Calculations of ingredients for effective standardization must be made in relation to the final product through of iterative calculations, which makes the manual process unfeasible. Thus, the objective of the present study was to develop a spreadsheet for ingredient calculation, with restrictions being the different concentrations of fat and water in order to standardize the final products. The spreadsheet was developed using the Excel 2007® Solver function, with just four input data: quantity of mass, water and fat content of the mass and fat content of the cream. The optimal solution was that which maximizes the amount of final product while meeting the stipulated constraints of fat and water. Results obtained with the spreadsheet were validated by processing the requeijão cheeses and comparison of the theoretical and practical parameters using the t-test. There was no significant difference between fat and water contents (p>0.10) estimated and verified in practice. Therefore, the use of the spreadsheet proved to be efficient for standardization of requeijão formulations

Use of response surface methodology to evaluate the extraction of Debaryomyces hansenii xylose reductase by aqueous two-phase system

In this work, to identify the most suitable operating conditions for purification of Debaryomyces hansenii UFV-170 XR, a 2^2 central composite design face-centeredwas used, varying temperature and tie-line length as the independent variables. The results collected for four response variables, specifically the XR partition coefficient, purification factor in the top phase, activity yield and selectivity, were analyzed by Response Surface Methodology

Liquid-liquid Equilibrium For Ternary Systems Containing A Sugar + A Synthetic Polymer + Water

This paper presents phase equilibrium data for ternary liquid mixtures containing glucose or maltose + poly(propylene glycol)s or block copolymers of ethylene oxide and propylene oxide units + water. The nonrandom two-liquid (NRTL) and the universal quasi-chemical activity coefficient (UNIQUAC) models were employed to model phase equilibrium, allowing the calculation of phase compositions. Good agreement between the experimental data and the model results was achieved.47613461350Albertsson, P.A., (1971) Partition of Cell Particles and Macromolecules 2nd Ed., , John Wiley: New YorkZaslavsky, B.Y., (1995) Aqueous Two-Phase Partitioning, , Marcel Dekker: New YorkMolyneaux, P., (1983) Water Soluble Synthetic Polymers: Properties and Behavior, , CRC: Boca Raton, FLPersson, J., Kaul, A., Tjerneld, F., Polymer recycling in aqueous two-phase extractions using thermoseparating ethylene oxide-propylene oxide copolymers (2000) J. Chromatogr. B, 743, pp. 115-126Johansson, H.-O., Karlström, G., Tjerneld, F., Temperature induced phase partitioning of peptides in water solutions of ethylene oxide and propylene oxide random copolymers (1997) Biochim. Biophys. Acta, 1335, pp. 315-325Silva, L.H.M., Meirelles, A.J.A., Phase equilibrium in aqueous mixtures of maltodextrin with polypropylene glycol (2001) Carbohydr. Polym., 46, pp. 267-274Silva, L.H.M., Meirelles, A.J.A., Phase equilibrium in polyethylene glycol/maltodextrin aqueous two-phase systems (2000) Carbohydr. Polym., 42, pp. 273-278Wu, Y.-T., Lin, D.-Q., Zhu, Z.-Q., Thermodynamics of aqueous two-phase systems-the effect of polymer molecular weight on liquid-liquid equilibrium phase diagrams by the modified NRTL Model (1998) Fluid Phase Equilib., 147, pp. 25-43Kang, C.H., Sandler, S.I.A., Thermodynamic model for two-phase aqueous polymer systems (1988) Biotechnol. Bioeng., 32, pp. 1158-1164Renon, H., Prausnitz, J.M., Estimation of parameters for the NRTL equation for excess gibbs energies of strongly nonideal liquid mixtures (1969) Ind. Eng. Chem. Process Des. Dev., 3, pp. 413-419Abrams, D.S., Prausnitz, J.M., Statistical thermodynamics of liquid mixtures: A new expression for the excess gibbs energy of partly or completely miscible systems (1975) AIChE J., 21, pp. 116-128Stragevitch, L., D'Avila, S.G., Application of a generalised maximum likelihood method in the reduction of multicomponent liquid-liquid equilibrium data (1997) Braz. J. Chem. Eng., 14, pp. 41-5

Statistical investigation of Kluyveromyces lactis cells permeabilization with ethanol by response surface methodology

The aim of our study was to select the optimal operating conditions to permeabilize Kluyveromyces lactis cells using ethanol as a solvent as an alternative to cell disruption and extraction. Cell permeabilization was carried out by a non-mechanical method consisting of chemical treatment with ethanol, and the results were expressed as \uf062-galactosidase activity. Experiments were conducted under different conditions of ethanol concentration, treatment time and temperature according to a central composite rotatable design (CCRD), and the collected results were then worked out by response surface methodology (RSM). Cell permeabilization was improved by an increase in ethanol concentration and simultaneous decreases in the incubation temperature and treatment time. Such an approach allowed us to identify an optimal range of the independent variables within which the beta-galactosidase activity was optimized. A maximum permeabilization of 2,816 mmol L-1 oNP min-1 g-1 was obtained by treating cells with 75.0% v/v of ethanol at 20.0\ub0C for 15.0 min. The proposed methodology resulted to be effective and suited for K. lactis cells permeabilization at a lab-scale and promises to be of possible interest for future applications mainly in the food industry

Use of response surface methodology to predict optimal conditions of Kluyveromyces lactis permeabilization by a physical method

Kluyveromyces lactis is an important commercial source of \u3b2-galactosidase, an enzyme of major concern for dairy industry. Among the methods for \u3b2-galactosidase recovery, cell permeabilization is the best alternative, but it is influenced by a number of operating conditions that need to be optimized. Aim of this study was to determine the best experimental conditions for yeast cells permeabilization by physical disruption with glass beads. Influence of glass beads and dry biomass amounts and process time was investigated varying these independent variables according to a central composite rotatable experimental design. A third order polynomial equation was fitted to the experimental data of permeabilized cells \u3b2-galactosidase activity, and the Response Surface Methodology employed for optimization. Optimum permeabilization conditions (0.90 g glass beads, 2.00 g dry biomass and 8.0 min of treatment) ensured a maximum \u3b2-galactosidase activity (6,434 mmol L-1 oNP min-1 g-1) in reasonable agreement with the yield reproduced under the same conditions (5,585.40 mmol L-1 oNP min-1 g-1)