82 research outputs found
Quatre lettres inédites d'Ange Goudar au marquis de Sade
No full textAnge Goudar : Four unpublished letters to the Marquis de Sade, presented by Maurice Lever.
Sade met Pierre-Ange Goudar, writer and adventurer, in 1775 during his flight to Italy after the "little girls" affair. An exchange of letters followed ; four of them, from the Sade family archives, are published here. Goudar expresses his opinions of Rome, Naples and Florence, his reflections on Cardinal Bernis and the Count of Saint-Germain, and speaks about his wife Sarah and his own writings. These unpublished pages reveal a hitherto totally unknown literary friendship between the author of Justine and another libertine called Goudar.Lever Maurice. Quatre lettres inédites d'Ange Goudar au marquis de Sade. In: Dix-huitième Siècle, n°23, 1991. Physiologie et médecine. pp. 223-232
Integrated Continuous Biomanufacturing: Perspectives from the Manufacturing Floor
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Computer programs for modeling mammalian cell batch and fed-batch cultures using logistic equations
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Special Section on Continuous Bioprocessing and Welcome Professor Liu to the Editorial Board
No full textBioprocess optimization for recombinant protein production from mammalian cells
No full textMammalian cells are being increasingly used to manufacture complex therapeutic proteins given their ability to properly fold and glycosylate these proteins. However, protein yields are low and process enhancements are necessary to ensure economically viable processes. Methods for yield improvement, bioprocess development acceleration and rapid quantification and monitoring of cell metabolism were investigated in this study. Recognizing the adverse effect of high PCO₂ on cell growth, metabolism and protein productivity, a novel PCO₂ reduction strategy based on NaHCO₃ elimination was investigated that decreased PCO₂ by 65-72%. This was accompanied by 68-123% increases in growth rate and 58-92% increases in productivity. To enable rapid and robust data analysis from early stage process development experiments, logistic equations were used to effectively describe the kinetics of batch and fed-batch cultures. Substantially improved specific rate estimates were obtained from the logistic equations when compared with current modeling approaches. Metabolic flux analysis was used to obtain quantitative information on cellular metabolism and the validity of using the balancing method for flux estimation was verified with data from isotope tracer studies. Error propagation from prime variables into specific rates and metabolic fluxes was quantified using Monte-Carlo analysis which indicated 8-22% specific rate error for 5-15% error in prime variable measurement. While errors in greater metabolic fluxes were similar to those in the corresponding specific rates, errors in the lesser metabolic fluxes were extremely sensitive to greater specific rate errors such that lesser fluxes were no longer representative of cellular metabolism. The specific rate to metabolic flux error relationship could be accurately described by the corresponding normalized sensitivity coefficient. A framework for quasi-real-time estimation of metabolic fluxes was proposed and implemented to serve as a bioprocess monitoring and early warning system. Methods for real-time oxygen uptake and carbon dioxide production rate estimation were developed that enabled rapid flux estimation. This framework was used to characterize cellular response to pH and dissolved oxygen changes in a process development experiment and can readily be applied to a manufacturing bioreactor. Overall, the approaches for protein productivity enhancement and rapid metabolism monitoring developed in this study are general with potential for widespread application to laboratory and manufacturing-scale perfusion and fed-batch mammalian cell cultivations.Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat
Accurate kinetic parameter estimation during progress curve analysis of systems with endogenous substrate production
No full textCoherent structures in turbulence: Their generation, identification, and contribution to tracer particle dispersion
No full textTurbulence is implicitly present or explicitly desired in many natural and industrial processes, such as, flow over solid surfaces, cloud formation, pollination, combustion, and chemical mixing. Hence, a better understanding of turbulence can aid in fuel saving by reducing drag in the case of flow over solid surfaces, namely, cars, airplanes, and ships. Furthermore, cloud formation models for refining weather modeling as well as the modeling of chemical mixing and combustion can be enhanced. However, there are different approaches to understand turbulence and in this thesis, turbulence is studied in terms of coherent structures..
Pair dispersion statistics and coherent structures
No full textPair dispersion is studied to model scalar transport in many natural and industrial applications. The link between the particle pair dispersion and coherent flow structures is explored in this work. This was done by kinematically simulating tracer particles in an ideal flow structure [4] extracted from an isotropic turbulent flow. It was found that the variation of the mean and the mean square separation lengths with time were qualitative similar to the results in actual turbulent flows. It was also observed that the quantitative results matched till 4-5 Kolmogrov time units. Ideal structure with two vortices and a shear layer was able to emulate the qualitative results. Is the combination of shear layer and one/two vortices is sufficient or necessary to emulate pair dispersion statistics needs to be studied in the future.Process and EnergyMechanical, Maritime and Materials Engineerin
Self-Sustaining Mechanisms in Wall Bounded Turbulence: Merging & auto-generation of vortices
No full textFor channel flow, we explore how a hairpin eddy may reach a threshold strength required to produce additional hairpins by means of auto-generation. This is done by studying the evolution of two eddies with different initial strengths (but both below the threshold strength), initial sizes and initial stream-wise spacing between them. The numerical procedure followed is similar to Zhou et al [1999]. The two eddies were found to merge into a single stronger eddy in case of a larger upstream and a smaller downstream eddy placed within a certain initial stream-wise separation distance. Subsequently, the resulting stronger eddy was observed to auto-generate new eddies. Merging of eddies thus is a viable explanation for the creation of the threshold strength eddies.Solid and Fluid MechanicsProcess and EnergyMechanical, Maritime and Materials Engineerin
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