The purification of pepsinogen from the stomach of red perch using aqueous two phase systems (ATPS) formed by polyethylene glycol (PEG) and salt at 4°C was optimized. Salt type, salt concentration, PEG molecular weight and PEG concentration had significant effects on total volume (TV), volume ratio (VR), enzyme activity (AE), protein content (CP), specific activity (SA), purification fold (PF) and recovery yield (RY). (NH4)2SO4 at 15% w/w concentration was selected as the optimum salt type and concentration. PEG 1500 at 18% w/w concentration was selected as the optimum PEG molecular weight and concentration. 15% (NH4)2SO4-18% PEG 1500, the optimal ATPS, was compared with ammonium sulfate fractionation (ASF). ATPS gave better partition of pepsinogen (SA of 5.40 U/mg, PF of 5.20 and RY of 86.6%) than ASF (SA of 2.55 U/mg, PF of 2.46, RY of 70.4%). / This is the electronic copy of partition of pepsinogen in aqueous two phase system method.

Carvone is a flavor and fragrance compound that is prominent in nature and is found in the essential oils of many plants. Carvone exists as two enantiomers, (R)-(-)-carvone which has a spearmint aroma and (S)-(+)-carvone which has a caraway aroma and can be used in a variety of applications: as a common food additive, as an antimicrobial/antifungal agent and as a potato sprout inhibitor. Carvone is currently produced by the extraction of essential oils from plants where the yield and quality of the extracted oil depends largely on successful agricultural production of dill, spearmint and caraway plants. Biotechnological production can offer a constant supply of carvone that is independent of several agricultural limitations. In this study, it was confirmed that the substrate and product of the microbial biotransformation of trans-carveol to (R)-(-)-carvone by Rhodococcus erythropolis DCL14 can be inhibitory to the cells at high concentrations. As such, a two phase partitioning bioreactor was employed where the function of the second phase (immiscible organic solvent or solid polymer beads) was to partition the inhibitory substrate into the aqueous phase at a rate governed by the metabolic demand of the cells and uptake the inhibitory product as it accumulated in the aqueous phase. Rational selection strategies were employed when determining the appropriate organic solvent and solid polymer to be used as the second phase. The performance of the reactor was evaluated based on volumetric productivity, length of biotransformation and total volume of substrate added to the reactor. The most successful reactor configuration was one in which styrene/butadiene copolymer beads were used as a second phase in the reactor and the fermentation medium was continuously circulated through an external extraction column packed with Hytrel® 8206 polymer beads. The volumetric productivity, length of biotransformation and total volume of substrate added to this reactor were 99 mg/L.h, 48.75 h and 35 mL, respectively whereas in the single phase benchmark reactor the performance indicators were only 31 mg/L.h, 15.25 h and 5 mL, respectively. These results clearly show the advantage of employing a partitioning bioreactor configuration for the biotechnological production of high value chemical species that exhibit cytotoxicity. / Thesis (Master, Chemical Engineering) -- Queen's University, 2008-01-24 10:20:09.589

In the present work, experimental data is obtained for the amount of air entrained by water and sugar solutions, of viscosities 3.6 and 4.7 centipoises, flowing down pipes of diameters 1.0, 1.5 and 2.0 inches. The dynamics of vapour entraining flow is discussed, and a method for calculating liquid flow rate at which pipe flows full is suggested. The experimental results have been presented in terms of some of the common dimensionless groups used in fluid mechanics in an attempt to develop an overall correlation scheme.

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Large amplitude interfacial waves are an important feature of annular gas-liquid two-phase flow. They act as a source of entrainment for liquid droplets. They occur for liquid flow rates above a critical value which depends on the gas flow rate. This thesis examines the formulation of a mathematical model to describe the behaviour of these nonlinear waves. Attention is focussed on the case of vertical upwards flow with reference to the experimental conditions for the rig at AERE Harwell. A comprehensive account is given of the limitations and similarities of mathematical models proposed by earlier research workers and their applicability to vertical two-phase flow. The most suitable approaches are found to be kinematic wave theory and an integral method. Experiments have been carried out at AERE Harwell to determine the relationship between liquid flux and film thickness required by kinematic wave theory and also to test some of the theory's predictions. There is a discussion of the difficulties involved in modelling the stresses exerted by the turbulent gas core on disturbance waves. The applicability of Benjamin's 'quasi-laminar' theory is considered. A linear stability analysis indicates that the interface is always unstable. The linear theory cannot provide a criterion for disturbance wave inception. Alternative explanations for wave inception are suggested. The SMAC (Simplified Marker And Cell) numerical method has been developed to model the time dependent behaviour of large amplitude waves in vertical annular two-phase flow. Finally, it is proposed that any realistic mathematical model for disturbance waves should be based upon kinematic wave theory and should take account of wave-breaking.