Membrane chromatography was investigated as an alternative method to packed-bed chromatography for protein recovery. The purification of lysozyme from egg white with Natrix adseptTM weak cation-exchange membranes was investigated under two different binding configurations: (1) a non-flow, static set-up with variable pH and sodium chloride (NaCl) concentrations during the binding and elution steps, and (2) a dynamic, cross-flow set-up with recycle at pH 7.5 and no NaCl addition during binding. The weak cation-exchange membrane consisted of a carboxylic acid-based, environmentally-responsive hydrogel layer bonded to a polymer matrix. Lysozyme was chosen to illustrate protein-membrane binding interactions due to its well-characterized nature and positive surface charge over a large pH range. For the static binding set-up, two sources of lysozyme were studied: pure lysozyme and egg whites treated with 60 % (v/v) ethanol (ESEW). Elution of bound protein was performed with 1 M NaCl under two pH strategies: binding and elution at a constant pH, and binding at pH 4.5 and variable elution pH. The highest maximum total protein binding capacity for pure lysozyme and ESEW was observed at pH 4.5 with no NaCl addition; however, poor total protein and lysozyme activity recovery were achieved during separation. As well, other egg white proteins, such as ovomucoid, were observed to bind to the membrane surface at pH 4.5, despite possessing similar charge polarity to the anionic membrane surface, indicating a non-electrostatic binding mechanism during operation below the membrane’s pKa (4.7). Based on the conditions tested, the highest total protein and lysozyme activity recovery was demonstrated for the separation of lysozyme from ESEW at pH 7.5 binding and elution and no NaCl addition. In the dynamic binding study, very high pure lysozyme dynamic binding capacity was achieved at 10 % breakthrough (167.3 mg/ml membrane for a 0.35 mg/ml lysozyme solution). The lysozyme dynamic binding capacity was 2.2 times greater than the static binding capacity under similar conditions, significantly higher than published results for other cation-exchange membranes. The separation of lysozyme from four lysozyme sources was tested: pure lysozyme, ESEW, and aqueous egg whites with (ASEW) and without (AEW) 100 mM NaCl. The highest lysozyme activity recovery during separation and lysozyme purity was achieved from the ESEW feed. Lysozyme separation from aqueous egg whites was not as effective, likely due to a high concentration of negatively-charged protein impurities fouling the surface of the membrane. Competitive binding to the membrane limited lysozyme binding and reduced the purity of the recovery elution stream. The application of feed-side pressure during the separation of ESEW produced a high purity, high recovery lysozyme elution stream with a significant reduction in processing time; however, protein aggregates were observed to form on the membrane surface, limiting the applicability of high-pressure operation and reducing protein functionality in the elution stream. The weak cation-exchange membrane system was shown to successfully separate out a target protein from a low concentration protein mixture through electrostatic interactions, and may be further applied to other protein systems.

Membrane chromatography was investigated as an alternative method to packed-bed chromatography for protein recovery. The purification of lysozyme from egg white with Natrix adseptTM weak cation-exchange membranes was investigated under two different binding configurations: (1) a non-flow, static set-up with variable pH and sodium chloride (NaCl) concentrations during the binding and elution steps, and (2) a dynamic, cross-flow set-up with recycle at pH 7.5 and no NaCl addition during binding. The weak cation-exchange membrane consisted of a carboxylic acid-based, environmentally-responsive hydrogel layer bonded to a polymer matrix. Lysozyme was chosen to illustrate protein-membrane binding interactions due to its well-characterized nature and positive surface charge over a large pH range. For the static binding set-up, two sources of lysozyme were studied: pure lysozyme and egg whites treated with 60 % (v/v) ethanol (ESEW). Elution of bound protein was performed with 1 M NaCl under two pH strategies: binding and elution at a constant pH, and binding at pH 4.5 and variable elution pH. The highest maximum total protein binding capacity for pure lysozyme and ESEW was observed at pH 4.5 with no NaCl addition; however, poor total protein and lysozyme activity recovery were achieved during separation. As well, other egg white proteins, such as ovomucoid, were observed to bind to the membrane surface at pH 4.5, despite possessing similar charge polarity to the anionic membrane surface, indicating a non-electrostatic binding mechanism during operation below the membrane’s pKa (4.7). Based on the conditions tested, the highest total protein and lysozyme activity recovery was demonstrated for the separation of lysozyme from ESEW at pH 7.5 binding and elution and no NaCl addition. In the dynamic binding study, very high pure lysozyme dynamic binding capacity was achieved at 10 % breakthrough (167.3 mg/ml membrane for a 0.35 mg/ml lysozyme solution). The lysozyme dynamic binding capacity was 2.2 times greater than the static binding capacity under similar conditions, significantly higher than published results for other cation-exchange membranes. The separation of lysozyme from four lysozyme sources was tested: pure lysozyme, ESEW, and aqueous egg whites with (ASEW) and without (AEW) 100 mM NaCl. The highest lysozyme activity recovery during separation and lysozyme purity was achieved from the ESEW feed. Lysozyme separation from aqueous egg whites was not as effective, likely due to a high concentration of negatively-charged protein impurities fouling the surface of the membrane. Competitive binding to the membrane limited lysozyme binding and reduced the purity of the recovery elution stream. The application of feed-side pressure during the separation of ESEW produced a high purity, high recovery lysozyme elution stream with a significant reduction in processing time; however, protein aggregates were observed to form on the membrane surface, limiting the applicability of high-pressure operation and reducing protein functionality in the elution stream. The weak cation-exchange membrane system was shown to successfully separate out a target protein from a low concentration protein mixture through electrostatic interactions, and may be further applied to other protein systems.

Scientists always face difficulties dealing with disjointed information. There is a need for a standardized and robust way to represent and exchange knowledge. Ontology has been widely used for this purpose. However, since research involves semantics and operations, we need to conceptualize both of them. In this thesis, we propose ReShare to provide a solution for this problem. Maximizing utilization while preserving the semantics is one of the main challenges when the heterogeneous knowledge is combined. Therefore, operational annotations were designed to allow generic object modeling, binding and representation. Furthermore, a test bed is developed and preliminary results are presented to show the usefulness and robustness of our approach. Moreover, two aggregation techniques for fusing ontology matchers are investigated as an initial work for building an algorithm which converts descriptive ontologies into operational ones.

Role-based approaches gain more and more interest for modeling and implementing variable software systems. Role models clearly separate static behavior represented by players and dynamic behavior modeled as roles which can be dynamically bound and unbound to players at run time. To support the execution of role-based systems, a dynamic binding mechanism is required. Especially, since instances of the same player type can play different roles in a single context, the binding mechanism is required to operate at instance level. In this paper, we introduce a mechanism called dynamic instance binding for implementing a runtime for role-based systems. It maintains a look-up table that allows the run-time system to determine and invoke the currently active role binding at instance level. We explain dynamic instance binding mechanism in detail and demonstrate that it is flexible enough to support both adaptation and evolution of software systems at run time.

This Master’s Thesis examines and documents challenges related to the flexible interchange of web services within a cross-cloud Service Oriented Computing scenario (SOC).Starting with a theoretical approach, hypotheses are defined and processed to create testing scenarios for a practical examination. Both examinations are used to identify possible challenges. Next, encountered challenges are described, discussed and classified. Lastly, solution approaches to identified challenges are presented. The solution approaches concern related topics, such as service standardization, semantic methods, heuristics, and security/trust mechanisms. Several approaches to different challenges are reviewed in this particular context, to present an overview for future research on the subject.It is remarkable that there will be more service standardization in the future, but to achieve full automation it will be, on the long run, necessary to evolve and adopt more sophisticated solution approaches such as semantic methods or heuristics.This work is embedded into the framework of a research co-operation between the Linnaeus University Växjö and the University of Applied Sciences Karlsruhe. Results however are also applicable to other research scenarios.

La chromatographie membranaire est une alternative à la chromatographie classique sur résine basée sur le transport convectif des solutés à travers une membrane microporeuse plutôt que par le transport diffusif des solutés dans les particules de résines. Cette technique présente les avantages de diminuer les phénomènes de diffusion, de réduire les temps de séjour et les pertes de charge, et de permettre la purification rapide de quantités importantes de molécules. La chromatographie membranaire connaît un fort succès commercial. Une gamme importante de membranes chromatographiques mettant en jeu différents mécanismes de rétention (échange d’ions, affinité, etc.) et différentes géométries (feuille, spirale, etc.) est actuellement commercialisée. Malgré ce succès, différents aspects relatifs à la chromatographie membranaire restent mal connus. Cette thèse de doctorat se propose de répondre à certaines questions relatives à cette technique / Membrane chromatography (MC) is an alternative to traditional resin packed columns chromatography. The solute mass transport in the membrane occurs in convective through-pores rather than in stagnant fluid inside the pores of the resins particles, which is limited by the slow diffusive transport. MC offers the main advantage of reducing diffusion phenomena, shorter residence time and lowered pressures drops, and thus, facilitates rapid purification of large quantities of molecules. A wide range of chromatographic membranes involving different molecules retention mechanisms (ion exchange, affinity, etc...) is now commercialized. Despite their success, the influence of the geometry of the membrane chromatography devices remains relatively unexplored from a theoretical point of view. This doctoral thesis is aimed to clarify some ambiguous points related to this technique