Refine
Year of publication
Document Type
- Article (35101)
- Doctoral Thesis (6450)
- Monograph/Edited Volume (5509)
- Postprint (3218)
- Review (2280)
- Part of a Book (978)
- Other (869)
- Preprint (566)
- Conference Proceeding (526)
- Part of Periodical (450)
Language
- English (29913)
- German (25766)
- Spanish (362)
- French (329)
- Italian (113)
- Russian (112)
- Multiple languages (65)
- Hebrew (36)
- Portuguese (25)
- Polish (24)
Keywords
- Germany (195)
- climate change (171)
- Deutschland (136)
- European Union (78)
- Sprachtherapie (77)
- diffusion (74)
- machine learning (74)
- Patholinguistik (73)
- patholinguistics (73)
- morphology (72)
Institute
- Institut für Biochemie und Biologie (5346)
- Institut für Physik und Astronomie (5314)
- Institut für Geowissenschaften (3536)
- Institut für Chemie (3436)
- Wirtschaftswissenschaften (2634)
- Historisches Institut (2482)
- Department Psychologie (2309)
- Institut für Mathematik (2128)
- Institut für Romanistik (2105)
- Sozialwissenschaften (1882)
A polymer analogous reaction for the formation of imidazolium and NHC based porous polymer networks
(2013)
A polymer analogous reaction was carried out to generate a porous polymeric network with N-heterocyclic carbenes (NHC) in the polymer backbone. Using a stepwise approach, first a polyimine network is formed by polymerization of the tetrafunctional amine tetrakis(4-aminophenyl)methane. This polyimine network is converted in the second step into polyimidazolium chloride and finally to a polyNHC network. Furthermore a porous Cu(II)-coordinated polyNHC network can be generated. Supercritical drying generates polymer networks with high permanent surface areas and porosities which can be applied for different catalytic reactions. The catalytic properties were demonstrated for example in the activation of CO2 or in the deoxygenation of sulfoxides to the corresponding sulfides.
4-Phenol diazonium salts undergo Pd-catalyzed Heck reactions with various styrenes to 4’-hydroxy stilbenes. In almost all cases higher yields and fewer side products were observed, compared to the analogous 4-methoxy benzene diazonium salts. In contrast, the reaction fails completely with 2- and 3-phenol diazonium salts. For these substitution patterns the methoxy-substituted derivatives are superior.
Under standard conditions the cross metathesis of allyl alcohols and methyl acrylate is accompanied by the formation of ketones, resulting from uncontrolled and undesired double bond isomerization. By conducting the CM in the presence of phenol, the catalyst loading and the reaction time required for quantiative conversion can be reduced, and isomerization can be suppressed. On the other hand, consecutive isomerization can be deliberately promoted by evaporating excess methyl acrylate after completing cross metathesis and by adding a base or silane as chemical triggers.
We present and discuss the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of five tetrachloridocuprate(II) complexes to supply a useful tool for the structural characterisation of the [CuCl4]2− moiety in the liquid state, for example in ionic liquids, or in solution. Bis(benzyltriethylammonium)-, bis(trimethylphenylammonium)-, bis(ethyltriphenylphosphonium)-, bis(benzyltriphenylphosphonium)-, and bis(tetraphenylarsonium)tetrachloridocuprate(II) were synthesised and characterised by elemental, IR, EPR and X-ray analyses. The results of the crystallographic analyses show distorted tetrahedral coordination geometry of all [CuCl4]2− anions in the five complexes and prove that all investigated complexes are stabilised by hydrogen bonds of different intensities. Despite the use of sterically demanding ammonium, phosphonium and arsonium cations to obtain the separation of the paramagnetic Cu(II) centres for EPR spectroscopy no hyperfine structure was observed in the EPR spectra but the principal values of the electron Zeeman tensor, g∥ and g⊥, could be determined. With these EPR data and the crystallographic parameters we were able to carry out a correlation study to anticipate the structural situation of tetrachloridocuprates in different physical states. This correlation is in good agreement with DFT calculations.
Intracellular photoactivation of caged cGMP induces myosin II and actin responses in motile cells
(2013)
Cyclic GMP (cGMP) is a ubiquitous second messenger in eukaryotic cells. It is assumed to regulate the association of myosin II with the cytoskeleton of motile cells. When cells of the social amoeba Dictyostelium discoideum are exposed to chemoattractants or to increased osmotic stress, intracellular cGMP levels rise, preceding the accumulation of myosin II in the cell cortex. To directly investigate the impact of intracellular cGMP on cytoskeletal dynamics in a living cell, we released cGMP inside the cell by laser-induced photo-cleavage of a caged precursor. With this approach, we could directly show in a live cell experiment that an increase in intracellular cGMP indeed induces myosin II to accumulate in the cortex. Unexpectedly, we observed for the first time that also the amount of filamentous actin in the cell cortex increases upon a rise in the cGMP concentration, independently of cAMP receptor activation and signaling. We discuss our results in the light of recent work on the cGMP signaling pathway and suggest possible links between cGMP signaling and the actin system.
I. Einführung
II. Die Kreaturwürde im schweizerischen
Recht – Entstehung und Konzeption
III. Inhalt und Bedeutung der Kreaturwürde
IV. Die besondere Herausforderung:
Würde der Pflanze
V. Kreaturwürde und Menschenwürde
VI. Kreaturwürde in der Gentechnologie
VII. Kreaturwürde im Tierschutz
VIII. Reflexion