New cyclopentadienylethylphosphane chelate complexes with unsymmetrical phosphane substitution

The syntheses, characterization, and some reactions of (phosphanylethyl) cyclopentadienyl chelate complexes of cobalt, rhodium, iridium, nickel, and chromium with unsymmetrical substitution at the phosphorus atom are described. The ligand systems were prepared by nucleophilic ring opening of spiro[2.4]hepta-4,6-diene with lithium tert-butylphenylphosphide or lithium tert-butylcyclohexylphosphide. The anionic ligands give the respective chelate complexes by treatment with metal halide reagents. In three cases it was possible to obtain X-ray crystal structure analyses. The cobalt chelate complex undergoes oxidative addition with a dihydrosilane, the reaction results in the formation of products with three stereogenic centers at phosphorus, cobalt, and silicon, which show dynamic behavior as indicated by VTNMR. The rhodium chelate complex undergoes oxidative addition of iodomethane with diastereoselective formation of the respective Rh(iii) chelate. While diastereoselectivity caused by a planar chiral indenyl ligand or by a stereogenic carbon center in the chelate backbone has earlier been observed, this is the first case of a stereoinduction by the stereogenic phosphorus ligand. Activation energies for the rotation of cobalt and rhodium chelates have also been determined by VTNMR. © 2011 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique

Das Proteom und Transkriptom von Clostridium acetobutylicum bei unterschiedlichen pH-Werten im Chemostaten

Das Bakterium Clostridium acetobutylicum wurde in einem systematischen Ansatz erstmals hinsichtlich des Wachstums, des Proteoms und des Transkriptoms bei unterschiedlichen pH-Werten vergleichend analysiert. Dabei wurden Markerproteine oder Gene des Stoffwechsels aufgedeckt und eine "Knock-Out"-Mutante eines potentiellen Schlüsselproteins des Hauptstoffwechsels näher analysiert. Insgesamt liefert diese Arbeit einen globalen Überblick über das Protein- und Transkriptmuster von C. acetobutylicum bei unterschiedlichen pH-Werten und gibt neue Einblicke in den komplexen Wechsel des Metabolismus

Exploring land-sea interactions: Insights for shaping territorial space

The interactions between land and sea are fundamental to human wellbeing. Within Europe, the 2014 Directive establishing a framework for maritime spatial planning (MSP Directive), which requires EU coastal member states to have marine spatial plans in place by 2021, also requires that MSP authorities should explicitly take into account land-sea interactions. This has stimulated a new phase of investigation into land-sea interactions in Europe. This paper aims to contribute to marine and coastal planning debates by reflecting on one of these investigations, the Maritime Spatial Planning and Land Sea Interactions (MSP-LSI) project. The paper starts by providing a historical overview of the growing attention being paid to LSI within the context of European policy making. This sets the context for the MSP-LSI project and the approach to exploring land-sea interactions it developed is outlined. The paper then uses examples from the project’s case study investigations to highlight and illustrate some of the wider insights the project revealed, both in relation to the extensive spatial footprint associated with selected maritime sectors and how marine space is being shaped by, and contributing to landward activity and governance agendas. It concludes by presenting a case not only for adopting a ‘one space’ perspective in MSP, but in territorial spatial planning and management regimes more generally.</jats:p

Critical behavior of the (2+1)-dimensional Thirring model

We investigate chiral symmetry breaking in the (2+1)-dimensional Thirring model as a function of the coupling as well as the Dirac flavor number Nf with the aid of the functional renormalization group. For small enough flavor number Nf < Nfc, the model exhibits a chiral quantum phase transition for sufficiently large coupling. We compute the critical exponents of this second order transition as well as the fermionic and bosonic mass spectrum inside the broken phase within a next-to-leading order derivative expansion. We also determine the quantum critical behavior of the many-flavor transition which arises due to a competition between vector and chiral-scalar channel and which is of second order as well. Due to the problem of competing channels, our results rely crucially on the RG technique of dynamical bosonization. For the critical flavor number, we find Nfc ~ 5.1 with an estimated systematic error of approximately one flavor.Comment: 28 pages, 14 figure

A systems biology approach to investigate the effect of pH-induced gene regulation on solvent production by Clostridium acetobutylicum in continuous culture

<p>Abstract</p> <p>Background</p> <p><it>Clostridium acetobutylicum </it>is an anaerobic bacterium which is known for its solvent-producing capabilities, namely regarding the bulk chemicals acetone and butanol, the latter being a highly efficient biofuel. For butanol production by <it>C. acetobutylicum </it>to be optimized and exploited on an industrial scale, the effect of pH-induced gene regulation on solvent production by <it>C. acetobutylicum </it>in continuous culture must be understood as fully as possible.</p> <p>Results</p> <p>We present an ordinary differential equation model combining the metabolic network governing solvent production with regulation at the genetic level of the enzymes required for this process. Parameterizing the model with experimental data from continuous culture, we demonstrate the influence of pH upon fermentation products: at high pH (pH 5.7) acids are the dominant product while at low pH (pH 4.5) this switches to solvents. Through steady-state analyses of the model we focus our investigations on how alteration in gene expression of <it>C. acetobutylicum </it>could be exploited to increase butanol yield in a continuous culture fermentation.</p> <p>Conclusions</p> <p>Incorporating gene regulation into the model of solvent production by <it>C. acetobutylicum </it>enables an accurate representation of the pH-induced switch to solvent production to be obtained and theoretical investigations of possible synthetic-biology approaches to be pursued. Steady-state analyses suggest that, to increase butanol yield, alterations in the expression of single solvent-associated genes are insufficient; a more complex approach targeting two or more genes is required.</p