Band 239, Heft 9 - Special Issue: From Nanostructure to Function; Guest Editors: Wolfgang Kautek, Giovanni Marletta and Eckart Ruhl

Ultrashort pulse laser sources are useful tools for micro- and nano-processing large band gap dielectric materials. One of the biggest advantages of these pulses is the possibility to reach high intensity peaks that promote absorption even in materials transparent to the laser wavelength. In addition, if the pulse temporal distribution is modified, energy absorption enables the ablation of small diameter holes with large depths. In this work, we present preliminary results that implement three types of pulses as precursors for glass dicing: Bandwidth-limited (30 fs at 785 nm), positively, and negatively dispersed Temporal Airy Pulses (TAP). The material of choice was 170 μm thick soda-lime glass, inscribed at 1 kHz repetition rate in tight (50× objective) and loose (20× objective) focusing conditions for different laser energies and scanning speeds. After laser processing, the glass was diced by mechanical stress, with a home built four-point bending stage. We analyzed the quality of the scribed lines at the surface and in cross-section after breaking, as well as the necessary breaking force for all three types of laser pulses. We report that positive TAP produced a neat, flat-cut edge on the glass samples compared with the other implemented pulses.

The study of patinas plays an important role in the field of cultural heritage. This review reports systematic investigations of European institutional co-operations. A stable patina relies on a certain atmospheric content of sulphur dioxide from industrial immissions. Since these are decreasing recently, patina phases change to aesthetically unsightly appearances. Analytical case studies are presented of selected bronze monuments and one bronze sculpture in Europe of the period from 1807 until 1934. These were the emperor Joseph II. Memorial (Vienna, Austria), the Maria Theresia Memorial (Vienna, Austria), the Gustav II Adolf Memorial (Gothenburg, Sweden), and the Marquês de Pombal Memorial (Lisbon, Portugal), as well as one Quadriga ensemble on the Austrian Parliament (Vienna, Austria). X-ray diffractometry (XRD), atomic absorption spectral analysis (AAS), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX), and optical microscopy provided insights into deterioration processes in urban and marine climates. On the basis of these findings suggestions are put forward for innovative conservation interventions on bronze and brass statuary monuments in open-air exposure including laser cleaning technologies which allow the selective removal of encrustations from original patinas.

Electrochemical synthesis is an effective method for ferrate ion (FeO 4 2− ) production. Ferrate ion production and oxygen evolution happen simultaneously during the transpassive anodic dissolution of iron and many iron-containing electrodes; the voltametric curves obtained during the experiments show only the total current produced by these two processes. Products from the aforementioned processes were examined in 45 % (m/m) aqueous NaOH solutions using the combination of dual dynamic voltammetry (DDV) with the rotating ring-disk electrode (RRDE) method (i.e., applying dynamic potential programs to the disk and the ring electrodes of the RRDE tip simultaneously). White cast iron (WCI) disk/Pt ring RRDE tips were used in the experiments. The electrode potential regions where ferrate ions and oxygen are formed could be efficiently identified by employing the DDV technique in conjunction with spectrophotometric data. The most suitable potential range for the electrochemical generation of ferrate ions in terms of current efficiency could also be determined. The results were compared to previous investigations using high-purity iron electrodes. The approach presented in this study indicated great potential for the concurrent detection of various dissolution products and offers opportunities for the initial assessment of the most favorable parameters in large-scale industrial operations through the utilization of small-scale systems.

Spontaneous and stimulated Raman spectromicroscopy is reported to investigate the cetuximab uptake in a head and neck cancer oral mucosa model and to unravel drug induced cellular changes in a label-free approach. Specifically, stimulated Raman spectromicroscopy is sensitive to probe the spatial distribution of cetuximab as well as drug-induced changes in spatial distributions of proteins, lipids, and DNA. The distinct vibrational bands of the CH 3 -stretch of proteins and the CH 2 -stretch of lipids indicate drug-induced cellular modifications, which are retrieved by a linear decomposition algorithm. Topical and systemic drug application pathways were studied, indicating an increased total protein content by a factor of ∼2 and ∼1.5, respectively, compared to an untreated control. Protein and lipid profiles as well as drug distributions were monitored, demonstrating the potential of Raman-based spectromicroscopy for probing changes induced by cetuixmab. Following cetuximab therapy, the relative protein content increases, while the lipid concentration decreases. Accumulation of lipid droplet-like structures near tumor cell membranes with less nucleic acid-like material in treated tumor oral mucosa models was also observed. The results are compared to related spectromicroscopy approaches involving fluorescence labels and label-free photothermal expansion indicating that stimulated Raman spectromicroscopy reveals sensitively biological post-treatment effects, while no reduction in tumor size occurs.

Chitin and keratin are naturally abundant biopolymers. They hold significant potential for sustainable applications due to their chemical structure, (nano)structural properties, biodegradability and nontoxicity. Chitin, a polysaccharide contained in exoskeletons of arthropods and the cell walls of fungi, forms strong hydrogen bonds that confer mechanical stability, which is ideal for use in protective structures and lightweight composites. Keratin, a fibrous protein found in vertebrate epithelial tissues such as wool, feathers and hair, is characterized by its high sulfur content and the formation of disulfide bonds, which provide both mechanical strength and flexibility. Utilizing chitin and keratin waste materials from the food industry, such as shrimp shells, chicken feathers and sheep wool, offers an eco-friendly alternative to synthetic materials and leverages their inherent biocompatibility. Additionally to the common macroscale reuse of chitin and keratin waste as fertilizer or livestock feed, using chitin and keratin as functional materials adds further uses for these versatile materials. The waste is increasingly being utilized specifically for its superior structural properties resulting from nanoscale functionalities. Chitin and keratin exhibit excellent thermal insulation properties, making them suitable for energy-efficient building materials. Their structural colours (e.g., in butterflies and birds), arising from micro- and nanoscale arrangements, offer non-fading colouration for textiles and coatings without the need for potentially harmful dyes. Additionally, these biopolymers provide lightweight yet strong materials ideal for packaging, consumer products, and – when smartly structured – even passive radiative cooling applications. Biomimetic designs based on chitin and keratin promise advancements across multiple fields by harnessing their natural properties and converting waste into high-value products, thereby addressing recycling issues and promoting sustainability.

Amyloids are protein aggregates involved in various protein condensation diseases. Our study aims to investigate the influence of glycine on the fibrillization mechanism of β -lactoglobulin (BLG), a model protein known to form amyloid fibrils from hydrolysed peptides in low pH aqueous solutions. We conducted atomistic molecular dynamics simulations of aqueous solutions of native and unfolded BLG in glycine buffer at pH 2.0. During the simulations we put our focus on analysing protein-protein/buffer interactions, structural electrostatic potential mapping, and the residence times of glycine and glycinium near specific amino acid residues. Glycinium cations were found to preferentially interact with specific protein residues potentially masking the outer disulfide bonds, affecting thiol deprotonation and influencing disulfide scrambling equilibrium. These interactions can potentially hinder hydrolysis and change the fibrillization pathway. Further investigations, such as constant pH MD simulations, simulations on disulfide bounded oligomers are warranted to validate these findings and deepen our understanding of protein aggregation mechanisms.