Bildung, Phasentransfer und Toxizität halogenierter Desinfektionsnebenprodukte im Aufbereitungszyklus von Schwimmbeckenwasser - Schwerpunkt stickstoffhaltige Verbindungen

In dieser Dissertation wurden Bildungsbedingungen von stickstoffhaltigen Desinfektionsnebenprodukten (DNP) im Schwimmbeckenwasser und deren Verteilung in die Luft von Hallenschwimmbädern untersucht. Die Stoffklasse der Chloramine und vor allem die Verbindung Trichloramin spielten bei den Untersuchungen die Hauptrolle. Um das Auftreten und die Relevanz der DNP zu berücksichtigen wurden chemisch-analytische Verfahren und toxikologische Tests durchgeführt

Productivity of Services: An Explorative Study in the Electrical and Chemical Engineering Sector

Knowledge intensive, complex services play a crucial role in the economy and welfare of developed countries. However, service productivity management is not as much investigated as productivity in manufacturing. In this paper a literature based and empirically confirmed approach to a comprehensive description of service productivity is provided. Existing service productivity models are evaluated according to a literature based developed evaluation scheme and the results of 32 semi-structured interviews with service experts from two German companies are presented. The results will lay the foundation for the development of a novel comprehensive service productivity mode

In vitro effects of hydroxyapatite containing toothpastes on dentin permeability after multiple applications and ageing

Abstract This in vitro study evaluated the effect of toothpastes with different active ingredients on dentin permeability using an extended protocol including multiple applications and several thermal ageing cycles in the presence or absence of human saliva. The Null hypothesis was that dentin permeability of a hydroxyapatite containing toothpaste (BR), a potassium nitrate (SP) and an arginine and calcium carbonate (EH) containing toothpaste were similar. Dentin permeability was measured as hydraulic conductance using a commercially available capillary flow system (Flodec, Geneva) and results were expressed as % relative to matching controls. Without saliva, the ranking (best first) of dentin permeability was BR(61%) < SP(87%) < EH(118%), with saliva EH(63%) < SP(72%) < BR(88%). Saliva increased or decreased permeability dependent upon the test material. BR reduced dentin permeability significantly more in absence of saliva, with saliva EH was superior to BR. Repeated material application decreased and thermal ageing increased dentin permeability. The different tooth pastes reduced permeability differently, the best being BR without saliva, the least EH without saliva. The newly introduced test conditions (ageing, saliva, multiple applications) influenced single results significantly, and as they better simulate the in vivo situation they should be considered to be included in further in vitro permeability testing of desensitizing preparations