Structural control of surface layer proteins at electrified interfaces investigated by in situ Fourier transform infrared spectroscopy

In situ Fourier Transform Infrared (FTIR) Spectroscopy complemented by Electrochemical Quartz Microbalance (EQMB) investigations allowed a detailed insight into the influence of the electrode potential on competing adsorption processes and bonding mechanisms of buffer ions and S-layer protein molecules of Lysinibacillus sphaericus CCM2177 at an electrified liquid/gold interface. The S-layer proteins adsorb on gold polarized positively of the point of zero charge by displacing perchlorate anions in the Helmholtz plane by their carboxylate groups. This is indicated by an increase of the peptide and carboxylate infrared absorption signals accompanied by a decrease of the perchlorate signal. S-layers interlinked laterally with Ca(2+) ions, positive of the point of zero charge, resulted in the formation of a crystalline layer participating in the Helmholtz layer. In contrast to the absence of the Ca(2+)-linkers, S-layers remain structurally intact also in the negative polarization domain where the Helmholtz layer is solely sustained by mainly solvated cations without participation of the negatively charged protein carboxylate functions.     

Melt Electrospinning

Melt electrospinning is relatively under‐investigated compared to solution electrospinning but provides opportunities in numerous areas, in which solvent accumulation or toxicity are a concern. These applications are diverse, and provide a broad set of challenges to researchers involved in electrospinning. In this context, melt electrospinning provides an alternative approach that bypasses some challenges to solution electronspinning, while bringing new issues to the forefront, such as the thermal stability of polymers. This Focus Review describes the literature on melt electrospinning, as well as highlighting areas where both melt and solution are combined, and potentially merge together in the future.     

Broadband-cascaded four-wave mixing in a photonic crystal fiber around 1 μm

To our knowledge, efficient generation of broadband four-wave mixing cascades centered at 1 μm and spanning 600 nm is experimentally demonstrated for the first time. This frequency comb is generated from a two-tone seed with a maximum peak power of 25 W in a low-dispersion photonic crystal fiber. It consists of up to 44 new idler waves generated symmetrically around the seed.     

Laser-based modification of wettablility for carbon fiber reinforced plastics

This paper presents a laser-based technique for surface preparation of carbon fiber reinforced plastics (CFRP) for bonded repair. Ablative and non-ablative treatment of the surface is produced by variation of laser power and the resulting surface energy determined by goniometric measurements. Wettability has been directly related to a calculated wetting envelope. The investigations show an additional major influence of the surface topography on the shear strength of the joint. The direction of the applied laser lines in relation to the fiber direction was identified as an essential influence for this roughness. A ns IR-laser demonstrates high potential for surface preparation as well as for selective ply removal. The laser prepared surfaces are examined through optical microscopy, scanning electron microscope (SEM), and contact angle measurements. The wettability studies show a significant increment in surface energy after laser treatment, in relation to non-treated as well as surface grinding samples.