[(Cp*Fe)3{(η3-As3)Fe}As6] und [(Cp*Fe)3As6][FeCl3(THF)], zwei neue Eisen–Arsen-Cluster mit As6 und As3-Fragmenten

[(Cp*Fe)₃{(η³-As₃)Fe}As₆] and [(Cp*Fe)₃As₆][FeCl₃(THF)], Two New Ironarsenide Cluster Containing As₆ and As₃ Fragments The compounds [(Cp*Fe)₃{(η³-As₃)Fe}As₆] ( 1 ) and [(Cp*Fe)₃As₆][FeCl₃(THF)], ( 2 ) can be obtained in good yields through the reaction of As₇(SiMe₃)₃ with FeCl₂ and LiCp*. Both compounds have been characterized by mass spectroscopy and crystal structure analysis. The As₇ nortricyclane frame of As₇(SiMe₃)₃ is still recognizable in 1 . According to the Wade rules the cation of 2 has 20 valence electrons inside the clustercore. This leads to a structure very similar to closo-B₉H₉^2–.     

Biological basis of enzyme-catalyzed polyester degradation: 59 C-terminal amino acids of poly(3-hydroxybutyrate) (PHB) depolymerase a from pseudomonas lemoignei are sufficient for PHB binding

Biodegradable polyesters such as biologically produced poly[(R)-3-hydroxybutyric acid], (PHB) other polyhydroxyalkanoic acids and related chemosynthetic polyesters have attracted industrial interest, and bacterial produced PHB is commercially available since 1990. A large variety of polyester degrading microorganisms have been found to be present in environment. The microorganisms decompose the polymers by secretion of extracellular polyester depolymerases and utilize low molecular weight degradation products for growth. Microbial polyester depolymerases have the unique property to be water soluble and to be able to bind specifically to polyester surfaces. The objective of this contribution is a functional analysis of a bacterial PHB depolymerase polyester binding domain. In addition, a detailed summary of the present knowledge on the biochemistry of enzymatic polyester hydrolysis is provided.     

NGO ‐ Eine dritte Kraft?

Zu einer Dachorganisation von Institutionen und Nichtregierungsorgansiationen, die sich für den Erhalt der Umwelt einsetzen, wurde in den letzten 50 Jahren die „International Union for Conservation of Nature”︁. Ihr Generaldirektor erläutert vor Rio+10, welche Rollen die „Dritte Kraft”︁, die Politik, der Markt und die chemische Industrie spielen.     

Synthesis and characterization of semifluorinated polymers and block copolymers

The goal of the investigation presented here was to evaluate the influence of semifluorinated side chains on the bulk structure and the surface properties of polysulfones with different chain structure. Thus, segmented block copolymers consisting of polysulfone and semifluorinated aromatic polyester segments as well as polysulfones having semifluorinated side chains randomly distributed over the polymer backbone were synthesized and characterized. Oxydecylperfluorodecyl side chains were used because of their strong tendency for self-organization. The influence of the chain architecture on the self-organization as well as on the surface properties, particularly the wetting behavior, was examined. It could be shown that despite of the higher self-organizing tendency of block copolymers the surface properties of both polymer types are comparable and depend only on the concentration of side chains.     

Multiscale Considerations for Sound Generation in Low Mach Number Flows

Classical approaches in aeroacoustics are mainly based on analytical solutions of the linear wave equations which are valid in the far field. The sound generation is approximated by source terms obtained from a flow simulation. This procedure designated as the ‘acoustic analogy’ was initiated in the classical work of Lighthill. In order to tackle the sound generation problem at low Mach numbers, we consider a multiple scale asymptotic analysis. As we deal with a fluid flow generating the sound itself, the asymptotic ansatz uses one time scale given by the flow convection, but two space scales due to the difference in fluid and sound velocity. The insight given by this analysis is used to obtain source terms describing the sound generation and perturbation equations for the sound propagation. Numerical results are shown for the example of a co‐rotating vortex pair.