The influence of Hofmeister salts was investigated on the cloud point of three poly(2-oxazoline)s, namely poly(2-ethyl-2-oxazoline) [PEtOx], poly(2-n-propyl-2-oxazoline) [PnPropOx], and poly(2-isopropyl-2-oxazoline) [PiPropOx]. In addition, a comb polymer based on oligo-2-ethyl-2-oxazoline side chains and a methacrylate backbone (POEtOxMA) was included in this investigation. It was found that the ionic response of the poly(2-oxazoline)s strongly depends on their hydrophilicity. The comb polymer POEtOxMA revealed a strikingly similar response to the salts as linear PEtOx even though the cloud points of the polymers in water differ. This indicates that the architecture does not significantly influence the effect of the Hofmeister ions, even though there is a difference in the absolute cloud point.

With the development of ultrafast electron and X-ray sources it is becoming possible to study structural dynamics with atomic-level spatial and temporal resolution. Because of their short mean free path, electrons are particularly well suited for investigating surfaces and thin films, such as the challenging and important class of membrane proteins. To perform single-shot diffraction experiments on protein crystals, an ultracold electron source was proposed, based on near-threshold photoionization of laser-cooled atoms, which is capable of producing electron pulses of both high intensity and high coherence. Here we show that high coherence electron pulses can be produced by femtosecond photoionization, opening up a new regime of ultrafast structural dynamics experiments. The transverse coherence turns out to be much better than expected on the basis of the large bandwidth of the femtosecond ionization laser pulses. This surprising result can be explained by analysis of classical electron trajectories.

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Vibrational signatures of Ac-Phe-AA-NH dipeptides are recorded and analysed in the far IR/THz spectral domain (100-800 cm, 3-24 THz), with the 'AA' amino acid chosen within the series 'AA' = Gly, Ala, Pro, Cys, Ser, Val. Phe stands for phenylalanine. IR-UV ion dip experiments are conducted on the free electron laser FELIX and combined with DFT-based molecular dynamics simulations for the calculation of the dynamical anharmonic vibrational spectra. The excellent agreements between the experimental and theoretical spectra of the Ac-Phe-AA-NH series allow us to make detailed and unambiguous mapping of the vibrational motions into three main domains: 700-800 cm for C-H waggings, 400-700 cm for N-H waggings, with a one-to-one signature per amide N-H backbone group, 0-400 cm for delocalized and large amplitude collective motions over the dipeptide backbone, with backbone torsional motions arising <100 cm.