Über die Darstellung von S2O5F2 aus Fluorsulfonsäure

Zusammenfassung Während die Umsetzung von HSO₃F mit P₂O₅ zu POF₃ führt, kann die Reaktion mit As₂O₅ AsF₅ oder ein flüchtiges Arsenfluoridfluosulfonat ergeben, welches sich zu Pyrosulfuryl-fluorid zersetzen läßt. S₂O₅F₂ ist thermisch in Glas bis über 300° stabil.Herrn Prof. Dr.A. Klemenc zum 70. Geburtstag gewidmet.     

Ultrafast thulium-doped fiber-oscillator with pulse energy of 4.3 nJ

A femtosecond fiber laser based on thulium-doped double-clad silica fiber with an internal dispersion compensation is presented that generates pulses at a center wavelength of 1976 nm with an energy of 4.3 nJ and a duration of 1.2 ps. The dechirped pulse duration is 294 fs. The pulse energy is more than 2 orders of magnitude above the pulse energy demonstrated previously. Mode locking is achieved using additive pulse mode locking, and dispersion compensation is facilitated by a grating stretcher arrangement.     

The oxygen-resistant [FeFe]-hydrogenase CbA5H harbors an unknown radical signal

[FeFe]-hydrogenases catalyze the reversible conversion of molecular hydrogen into protons and electrons with remarkable efficiency. However, their industrial applications are limited by their oxygen sensitivity. Recently, it was shown that the [FeFe]-hydrogenase from Clostridium beijerinckii (CbA5H) is oxygen-resistant and can be reactivated after oxygen exposure. In this work, we used multifrequency continuous wave and pulsed electron paramagnetic resonance (EPR) spectroscopy to characterize the active center of CbA5H, the H-cluster. Under oxidizing conditions, the spectra were dominated by an additional and unprecedented radical species. The generation of this radical signal depends on the presence of an intact H-cluster and a complete proton transfer pathway including the bridging azadithiolate ligand. Selective ⁵⁷Fe enrichment combined with isotope-sensitive electron-nuclear double resonance (ENDOR) spectroscopy revealed a spin density distribution that resembles an H-cluster state. Overall, we uncovered a radical species in CbA5H that is potentially involved in the redox sensing of CbA5H.

Electron paramagnetic resonance spectroscopy revealed an unprecedented radical species in the oxygen-resistant [FeFe]-hydrogenase CbA5H. Analysis of the isotope-sensitive data suggests that it is related to the active site, the H-cluster.     

Comment on “Solitons in the Heimburg–Jackson model of sound propagation in lipid bilayers are enabled by dispersion of a stiff membrane” by M. Drab et al.

The European Physical Journal E - Inference problems for two-dimensional snapshots of rotating turbulent flows are studied. We perform a systematic quantitative benchmark of point-wise and...