Betriebsverhalten einer Wärmepumpenanlage mit Luftkollektor und Erdspeicher

This study is concerned with the investigation of the performance of a heat pump system with solar air heater and earth storage as a source of heat. After the experimental check of the collector and the earth storage a complete heating system was constructed and studied over a heating period. The heating system was simulated by a computer program. This program treats the solar air collector and the earth storage by the measured characteristics of their performance. A house simulation program used the ambient temperature, the solar radiation and wind speed to calculate the heating load of a residental house. The calculations resulting from the simulation program showed the performance of the system under the different weather conditions of Jülich and Hamburg as well as the suitable regulation and the right dimensions of the mean components

Bioartifizielles Pankreas Schlussbericht

Within the co-ordinating program 'Bioartificial Pancreas' of the institutions mentioned above methods were developed to isolate islets of Langerhans from the pancreas of various species and to transplant them in order to treat an experimentally induced diabetes in rats, mice or pigs. For the prevention of the immunological rejection of the recipient organism the islets were either placed into hollow fibres or transplanted as microcapsules within alginates. The program was very successful in establishing the technology for isolation and purification of several 100,000 of islets from the pancreas of bigger animals and of humans. Within the period of support one female patient was transplanted with allogene free islets which resulted in long-lasting insulin independence. In the meantime further patients have been successfully transplanted. With the help of microencapsulated islets it was possible to induce long-lasting (>100 days) normoglycemia in diabetic rats or mice. Similar success did not yet occur in the treatment of pigs. Hollow fibres were not found useful to induce normoglycemia in diabetic rodents. So far, immunoprotection of islets of Langerhans with alignate microencapsulation seems to be possible in principle. However, further progress in membrane technology is necessary for the use of the method in bigger animals and in men. (orig.)SIGLEAvailable from TIB Hannover: F98B862 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Bonn (Germany)DEGerman

Betriebsverhalten einer Waermepumpenanlage mit Luftkollektor und Erdspeicher

TIB: RA 831 (2030) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Biocompatibility and immunology in the encapsulation of islets of Langerhans (bioartificial pancreas)

Successful transplantation of encapsulated islets (bioartificial pancreas) would circumvent problems of islet availability and rejection in the treatment of insulin-dependent diabetes with biological organ replacement. Alginates are widely used as a hydrogel matrix or membrane for immunoprotected transplantation. A major problem in the use of diffusion-based devices is the biocompatibility of the material used. The foreign body reaction after implantation of empty microcapsules into different compartments in rats, dogs and pigs is evaluated in this article. However, biocompatibility of the bioartificial pancreas has three different aspects: reaction of the entrapped islet to the encapsulation technique and material; reaction of the recipient against the incorporated device (= foreign body reaction); and finally the reaction of the recipient against the encapsulated islet (= immunology of bioartificial pancreas). It is obvious from different experiments that even ii foreign body reactions (reactions against material):are almost abolished the recipient may react against material released from the encapsulated islet. in conclusion, transplantation of encapsulated islets induces various morphological reactions (i.e. inflammation and fibrosis) as a result of a variety of donor and recipient related factors. Therefore, the use of an adequate animal model that reflects the human situation is essential for progress in the development of a bioartificial pancreas