Mussel mooring made mighty by metals
Mussels produce an exceptional proteinaceous adhesive so they can withstand waves and currents. Metal ions bound to modified tyrosine residues play an important role in reinforcing the adhesive. Priemel
et al
. brought together a variety of spectroscopy and microscopy techniques to study the cellular mechanisms involved in adhesive fabrication in mussels (see the Perspective by Wilker). They found that metal ion–rich vesicles are secreted alongside vesicles containing the adhesive protein and mix in a microfluidic-like process within interconnected microchannels found in the lateral duct of the mussel foot to create porous, adhesive plaque filaments. —MAF
The recently developed 3D micro X-ray fluorescence spectroscopy (3D Micro-XRF) enables three-dimensional resolved, nondestructive investigation of elemental distribution in samples in the micrometer regime. Establishing a reliable quantification procedure is the precondition to render this spectroscopic method into a true analytical tool. One prominent field of application is the investigation of stratified material. A procedure for the quantitative reconstruction of the composition of stratified material by means of 3D Micro-XRF is proposed and validated. With the procedure, it is now possible to determine nondestructively the chemical composition and the thickness of layers. As no adequate stratified reference samples were available for validation, stratified reference material has been developed that is appropriate for 3D Micro-XRF or other depth-sensitive X-ray techniques.
In this work, a novel laser-produced plasma source is presented which delivers pulsed broadband soft X-radiation in the range between 100 and 1200 eV. The source was designed in view of long operating hours, high stability, and cost effectiveness. It relies on a rotating and translating metal target and achieves high stability through an on-line monitoring device using a four quadrant extreme ultraviolet diode in a pinhole camera arrangement. The source can be operated with three different laser pulse durations and various target materials and is equipped with two beamlines for simultaneous experiments. Characterization measurements are presented with special emphasis on the source position and emission stability of the source. As a first application, a near edge X-ray absorption fine structure measurement on a thin polyimide foil shows the potential of the source for soft X-ray spectroscopy.
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