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Different Mathematical Models (different + mathematical_models)
Selected AbstractsComparison of different algorithms to calculate electrophoretic mobility of analytes as a function of binary solvent compositionELECTROPHORESIS, Issue 10 2003Abolghasem Jouyban Abstract Ten different mathematical models representing the electrophoretic mobility of analytes in capillary electrophoresis in mixed solvents of different composition have been compared using 32 experimental data sets. The solvents are binary mixtures of water-methanol, water-ethanol and methanol-ethanol, respectively. Mean percentage deviation (MPD), overall MPD (OMPD) and individual percentage deviation (IPD) have been considered as comparison criteria. The results showed that a reorganized solution model, namely the combined nearly ideal binary solvent/Redlich-Kister equation, is the most accurate model among other similar models concerning both correlation ability and prediction capability. [source] Protein purification using chromatography: selection of type, modelling and optimization of operating conditionsJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2009J. A. Asenjo Abstract To achieve a high level of purity in the purification of recombinant proteins for therapeutic or analytical application, it is necessary to use several chromatographic steps. There is a range of techniques available including anion and cation exchange, which can be carried out at different pHs, hydrophobic interaction chromatography, gel filtration and affinity chromatography. In the case of a complex mixture of partially unknown proteins or a clarified cell extract, there are many different routes one can take in order to choose the minimum and most efficient number of purification steps to achieve a desired level of purity (e.g. 98%, 99.5% or 99.9%). This review shows how an initial 'proteomic' characterization of the complex mixture of target protein and protein contaminants can be used to select the most efficient chromatographic separation steps in order to achieve a specific level of purity with a minimum number of steps. The chosen methodology was implemented in a computer- based Expert System. Two algorithms were developed, the first algorithm was used to select the most efficient purification method to separate a protein from its contaminants based on the physicochemical properties of the protein product and the protein contaminants and the second algorithm was used to predict the number and concentration of contaminants after each separation as well as protein product purity. The application of the Expert System approach was experimentally tested and validated with a mixture of four proteins and the experimental validation was also carried out with a supernatant of Bacillus subtilis producing a recombinant , -1,3-glucanase. Once the type of chromatography is chosen, optimization of the operating conditions is essential. Chromatographic elution curves for a three-protein mixture (, -lactoalbumin, ovalbumin and , -lactoglobulin), carried out under different flow rates and ionic strength conditions, were simulated using two different mathematical models. These models were the Plate Model and the more fundamentally based Rate Model. Simulated elution curves were compared with experimental data not used for parameter identification. Deviation between experimental data and the simulated curves using the Plate Model was less than 0.0189 (absorbance units); a slightly higher deviation [0.0252 (absorbance units)] was obtained when the Rate Model was used. In order to optimize operating conditions, a cost function was built that included the effect of the different production stages, namely fermentation, purification and concentration. This cost function was also successfully used for the determination of the fraction of product to be collected (peak cutting) in chromatography. It can be used for protein products with different characteristics and qualities, such as purity and yield, by choosing the appropriate parameters. Copyright © 2008 John Wiley & Sons, Ltd. [source] Modelling of air drying of Hac,haliloglu-type apricotsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2006Hakan Okyay Menges Abstract In this study a laboratory dryer was used for the thin layer drying of sulfured and non-sulfured apricots. The moisture ratio values throughout the drying process were calculated by 14 different mathematical models, namely Newton, Page, modified Page, modified Page-II, Henderson and Pabis, logarithmic, two-term, two-term exponential, Wang and Singh, Thompson, diffusion approximation, modified Henderson and Papis, Verma et al. and Midilli et al. models. Root mean square error, reduced chi-square, mean bias error, adjusted R -square and modelling efficiency were used as statistical parameters to determine the most suitable model among them. According to the results, the Page model was chosen to explain the thin layer drying behaviour of sulfured and non-sulfured apricots. The effects of drying air temperature (T) and velocity (V) on the constants and coefficients of the best moisture ratio model were determined by multiple regression analysis. The moisture ratio (MR) could be predicted by the Page model equation MR = exp(,ktn) with constants and coefficients k = 0.470893 + 0.078775V and n = 0.017786 exp(0.051935T) for sulfured apricots and k = 4.578252 + 1.144643T and n = 0.888040 + 0.145559V for non-sulfured apricots. It is possible to predict the moisture content of the product with the generalised Page model incorporating the effects of drying air temperature and velocity on the model constants and coefficients in the ranges T = 70,80 °C and V = 1,3 m s,1. This developed model showed acceptable agreement with the experimental results, explained the drying behaviour of the product and could also be used for engineering applications. Copyright © 2005 Society of Chemical Industry [source] Will the 13C-octanoic acid breath test ever replace scintigraphy as the gold standard to assess gastric emptying?NEUROGASTROENTEROLOGY & MOTILITY, Issue 10 2009K. Verbeke Abstract, The applicability of the 13C-octanoic acid breath test for the assessment of gastric emptying is discussed. In the current issue of this journal, Keller and her colleagues described the application of different mathematical models for analysis of the 13C-octanoic acid test in a very large patient population. [source] | ||||||||||