Search

In the field of tissue engineering, there is an increasing demand for non-destructive methods to quantify the synthesis of extracellular matrix (ECM) components such as collagens, elastin or sulphated glycosaminoglycans (sGAGs) in vitro as a quality control before clinical use. This thesis has investigated a new, non-invasive method for monitoring the synthesis of elastin, one of the most important structural components of ECM in cardiovascular tissue engineering. It was shown that the measurement of tropoelastin as marker of elastin synthesis correlated with the amount of elastin retained in fibrin gels with a Pearson correlation coefficient of 0.99. Even though this experiment does not include the whole complexity of elastin synthesis, the results found here are encouraging for further studies in this field. In a next step dynamic cultivation conditions and more complex tissue constructs should be investigated. An important question left is whether tropoelastin can be detected in commonly used amounts of bioreactor mediums in tissue engineered heart valves and/or vascular grafts. It is also of particular interest whether mechanical stimulation during dynamic cultivation leads to a significant increase of elastin synthesis in comparison to statically cultivated fibrin gels. In conclusion, a comprehensive evaluation of ECM synthesis is not possible only by assessing the synthesis of tropoelastin: as ECM components interact concerning synthesis and tissue development, the synthesis of sulphated glycosaminoglycans and collagens is also of fundamental interest.

Seitliche Korrekturen von Prepreg Tows während eines Automated Fiber Placement Prozesses können zur Einhaltung beziehungsweise Erhöhung der geforderten Bauteilqualität dienen. Die dabei auftretenden Scherkräfte zwischen Werkzeugoberfläche, Material und Kompaktierungsrolle beeinflussen das Materialverhalten während des Korrekturprozesses. Dieses Verhalten in Abhängigkeit verschiedener Ablegeparameter wie Anpresskraft, Korrekturwinkel oder Ablegegeschwindigkeit wurde hier untersucht. Mit Hilfe eines Faserkantendetektors konnte die Qualität des abgelegten Materials bezüglich Position, Geometrie oder Defekte erfasst werden. Die Versuche haben gezeigt, dass eine Variation der Parameter erhebliche Einflüsse auf das abgelegte Material haben kann und dass es aufgrund der seitlichen Auslenkungen zu Abweichungen zwischen der real abgelegten Bahn und der Sollbahn kommt. Erst durch die hier ermittelten Erkenntnisse über das Materialverhalten kann eine online Bahnkorrektur erfolgreich durchgeführt werden und die Qualität des Ablegeprozesses im Vergleich zur aktuellen Fertigungstechnologien gesteigert werden.

In the practice of software development contexts have been only implicitly modeled and transformed in fixed part of software. The information about context is dispersed in objects across the application. Each context change leads to modification or new development of the software. The context modeling helps developer to separate context objects from contextdependent objects. It allows better reuse of analysis, design and implementation models, if the context of certain objects is changed. The context modeling is interesting and necessary, when the software should be agile - i.e. when the environment and the condition of the software could be changed permanently, e.g. in case of platform for virtual enterprises. The paper introduces a novel approach to support processes within generic platforms for virtual enterprises: the context-based approach. The main advantage of the approach lies in its generic capacity, which allows the users to define processes flexibly to support their own enterprises. In this paper, we discuss further the phenomenon of extra-context logic, its modeling and its application case. The information of extra-context logic provides not only the better understanding of application domain, but also can be used by a wizard to support the interaction of users working with multiple systems.