Direct Observation of the Ethyl Radical in the Pyrolysis of Ethane

We report the first direct detection of ethyl radical in the pyrolysis of ethane. Observation of this vital intermediate was made possible in this extremely reactive environment by the use of a microreactor coupled with synchrotron radiation and photoelectron photoion coincidence (PEPICO) spectroscopy, despite its short lifetime and low concentration. Together with ab-initio master equation-calculated rates and fully coupled computational fluid dynamics simulations, our measurements show that even under the low pressures and short residence times in our experiment, ethyl formation can only be explained by bimolecular reactions; the most important is the catalytic attack of ethane by H atoms, which are then regenerated by decomposition of the nascent ethyl radicals. Our results complete the observation of all hypothesized intermediates in this industrially important process and highlight the need for further studies under additional conditions using similar methods to improve existing models and optimize process chemistries.     

Salt crystallization during evaporation: impact of interfacial properties

Salt damage in stone results in part from crystallization of salts during drying. We study the evaporation of aqueous salt solutions and the crystallization growth for sodium sulfate and sodium chloride in model situations: evaporating droplets and evaporation from square capillaries. The results show that the interfacial properties are of key importance for where and how the crystals form. The consequences for the different forms of salt crystallization observed in practice are discussed.     

Probing Cell-Surface Interactions in Fungal Cell Walls by High-Resolution 1H-Detected Solid-State NMR Spectroscopy

Solid-state NMR (ssNMR) spectroscopy facilitates the non-destructive characterization of structurally heterogeneous biomolecules in their native setting, for example, comprising proteins, lipids and polysaccharides. Here we demonstrate the utility of high and ultra-high field ¹H-detected fast MAS ssNMR spectroscopy, which exhibits increased sensitivity and spectral resolution, to further elucidate the atomic-level composition and structural arrangement of the cell wall of Schizophyllum commune, a mushroom-forming fungus from the Basidiomycota phylum. These advancements allowed us to reveal that Cu(II) ions and the antifungal peptide Cathelicidin-2 mainly bind to cell wall proteins at low concentrations while glucans are targeted at high metal ion concentrations. In addition, our data suggest the presence of polysaccharides containing N-acetyl galactosamine (GalNAc) and proteins, including the hydrophobin proteins SC3, shedding more light on the molecular make-up of cells wall as well as the positioning of the polypeptide layer. Obtaining such information may be of critical relevance for future research into fungi in material science and biomedical contexts.