@phdthesis{Wattebled2006,
  author    = {Wattebled, Laurent},
  title     = {Oligomeric surfactants as novel type of amphiphiles : structure - property relationships and behaviour with additives},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12855},
  school      = {Universit{\"a}t Potsdam},
  year      = {2006},
  abstract  = {The properties of a series of well-defined new surfactant oligomers (dimers to tetramers)were examined. From a molecular point of view, these oligomeric surfactants consist of simple monomeric cationic surfactant fragments coupled via the hydrophilic ammonium chloride head groups by spacer groups (different in nature and length). Properties of these cationic surfactant oligomers in aqueous solution such as solubility, micellization and surface activity, micellar size and aggregation number were discussed with respect to the two new molecular variables introduced, i.e. degree of oligomerization and spacer group, in order to establish structure - property relationships. Thus, increasing the degree of oligomerization results in a pronounced decrease of the critical micellization concentration (CMC). Both reduced spacer length and increased spacer hydrophobicity lead to a decrease of the CMC, but to a lesser extent. For these particular compounds, the formed micelles are relatively small and their aggregation number decreases with increasing the degree of oligomerization, increasing spacer length and sterical hindrance. In addition, pseudo-phase diagrams were established for the dimeric surfactants in more complex systems, namely inverse microemulsions, demonstrating again the important influence of the spacer group on the surfactant behaviour. Furthermore, the influence of additives on the property profile of the dimeric compounds was examined, in order to see if the solution properties can be improved while using less material. Strong synergistic effects were observed by adding special organic salts (e.g. sodium salicylate, sodium vinyl benzoate, etc.) to the surfactant dimers in stoichiometric amounts. For such mixtures, the critical aggregation concentration is strongly shifted to lower concentration, the effect being more pronounced for dimers than for analogous monomers. A sharp decrease of the surface tension can also be attained. Many of the organic anions produce viscoelastic solutions when added to the relatively short-chain dimers in aqueous solution, as evidenced by rheological measurements. This behaviour reflects the formation of entangled wormlike micelles due to strong interactions of the anions with the cationic surfactants, decreasing the curvature of the micellar aggregates. It is found that the associative behaviour is enhanced by dimerization. For a given counterion, the spacer group may also induce a stronger viscosifying effect depending on its length and hydrophobicity. Oppositely charged surfactants were combined with the cationic dimers, too. First, some mixtures with the conventional anionic surfactant SDS revealed vesicular aggregates in solution. Also, in view of these catanionic mixtures, a novel anionic dimeric surfactant based on EDTA was synthesized and studied. The synthesis route is relatively simple and the compound exhibits particularly appealing properties such as low CMC and σCMC values, good solubilization capacity of hydrophobic probes and high tolerance to hard water. Noteworthy, mixtures with particular cationic dimers gave rise to viscous solutions, reflecting the micelle growth.},
  language  = {en}
}
@phdthesis{Wegewitz2007,
  author    = {Wegewitz, Uta Elke},
  title     = {Genetische und metabolische Regulation von Adiponectin : Resultate von in vitro und humanen in vivo Studien},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16062},
  school      = {Universit{\"a}t Potsdam},
  year      = {2007},
  abstract  = {{\"U}bergewicht, Diabetes oder Fettstoffwechselst{\"o}rungen sind mit erniedrigten Adiponectinspiegeln assoziiert. Eine Modulation des Adiponectins kann durch genetische und metabolische Gegebenheiten erfolgen. Das Ziel dieser Arbeit war die Analyse von Faktoren, welche die Adiponectinspiegel beeinflussen k{\"o}nnen, sowie eine Charakterisierung der Oligomerverteilung unter verschiedenen metabolischen Bedingungen. In der MeSyBePo-Kohorte waren die zirkulierenden Adiponectinspiegel mit den Promotorpolymorphismen ADIPOQ -11377 C/G und ADIPOQ -11391 G/A im Adiponectingen assoziiert. Im Hinblick auf die metabolischen Faktoren korrelierte Adiponectin eng mit Parametern des Glukose- und Fettstoffwechsels sowie dem {\"U}bergewicht. Innerhalb von hyperinsulin{\"a}mischen euglyk{\"a}mischen Clamps f{\"u}hrte eine akute Hyperinsulin{\"a}mie zu einer Abnahme der Adiponectinspiegel. Adiponectin zirkuliert im Serum als hochmolekulare (HMW), mittelmolekulare (MMW) und niedrigmolekulare (LMW) Spezies. Mit zunehmendem K{\"o}rpergewicht konnte eine Verlagerung von HMW-Spezies hin zu den LMW-Spezies beobachtet werden. Durch eine moderate Gewichtsabnahme erh{\"o}hten sich die Anteile an HMW- und MMW-Adiponectin wieder. W{\"a}hrend sich in Abh{\"a}ngigkeit vom Glukosemetabolismus keine Unterschiede in den Gesamtspiegeln ergaben, wurden bei Personen mit normaler Glukosetoleranz signifikant h{\"o}here Anteile an MMW-Adiponectin detektiert als bei Personen mit einem gest{\"o}rten Glukosestoffwechsel. Insgesamt scheinen die HMW- und MMW-Spezies gegens{\"a}tzlich zur LMW-Spezies reguliert zu werden. Die Arbeit unterstreicht die wichtige Rolle des Adiponectins im Glukose- und Fettstoffwechsel sowie bei einer Adipositas in vivo. Dabei waren {\"A}nderungen der Adiponectinspiegel bei Vorliegen von Insulinresistenz und Adipositas stets mit einer Umverteilung der Oligomerfraktionen verbunden. Vor allem die HMW- und MMW-Spezies des Adiponectins scheinen von entscheidender Bedeutung zu sein.},
  language  = {de}
}