Open Access

Die Wissenschaft der Akustik mit ihrer Vielfallt und Interdisziplinarität bietet hervorragende Möglichkeiten an beruflichen Betätigungsfeldern und hat viele von uns in ihren Bann gezogen. Ausbildung in der Akustik bedeutet mehr als Studierenden nur Wissen und Fähigkeiten zu vermitteln. Eigentlich ist nach dem Studium auch der Lernprozess nicht abgeschlossen, sondern wie viele Akustiker:innen meinen, fängt dieser erst dann richtig an. Um eine sehr gute Ausbildung zu gestalten, bedarf es neben Vorbildern an Personen auch Lehrformate, Methoden und Tools. Die folgenden sechs Kurzbeiträge sind Beispiele gelungener Maßnahmen in der Ausbildung der Akustik und sollen anregen, die Qualität in der Lehre stetig zu verbessern.

The development of new materials that mimic cartilage and its function is an unmet need that will allow replacing the damaged parts of the joints, instead of the whole joint. Polyvinyl alcohol (PVA) hydrogels have raised special interest for this application due to their biocompatibility, high swelling capacity and chemical stability. In this work, the effect of post-processing treatments (annealing, high hydrostatic pressure (HHP) and gamma-radiation) on the performance of PVA gels obtained by cast-drying was investigated and, their ability to be used as delivery vehicles of the anti-inflammatories diclofenac or ketorolac was evaluated. HHP damaged the hydrogels, breaking some bonds in the polymeric matrix, and therefore led to poor mechanical and tribological properties. The remaining treatments, in general, improved the performance of the materials, increasing their crystallinity. Annealing at 150 °C generated the best mechanical and tribological results: higher resistance to compressive and tensile loads, lower friction coefficients and ability to support higher loads in sliding movement. This material was loaded with the anti-inflammatories, both without and with vitamin E (Vit.E) or Vit.E + cetalkonium chloride (CKC). Vit.E + CKC helped to control the release of the drugs which occurred in 24 h. The material did not induce irritability or cytotoxicity and, therefore, shows high potential to be used in cartilage replacement with a therapeutic effect in the immediate postoperative period.

Hypericin has large potential in modern medicine and exhibits fascinating structural dynamics, such as multiple conformations and tautomerization. However, it is difficult to study individual conformers/tautomers, as they cannot be isolated due to the similarity of their chemical and physical properties. An approach to overcome this difficulty is to combine single molecule experiments with theoretical studies. Time-dependent density functional theory (TD-DFT) calculations reveal that tautomerization of hypericin occurs via a two-step proton transfer with an energy barrier of 1.63 eV, whereas a direct single-step pathway has a large activation energy barrier of 2.42 eV. Tautomerization in hypericin is accompanied by reorientation of the transition dipole moment, which can be directly observed by fluorescence intensity fluctuations. Quantitative tautomerization residence times can be obtained from the autocorrelation of the temporal emission behavior revealing that hypericin stays in the same tautomeric state for several seconds, which can be influenced by the embedding matrix. Furthermore, replacing hydrogen with deuterium further proves that the underlying process is based on tunneling of a proton. In addition, the tautomerization rate can be influenced by a λ/2 Fabry–Pérot microcavity, where the occupation of Raman active vibrations can alter the tunneling rate.

The isothermal curing of melamine resin is investigated by in-line infrared spectroscopy at different temperatures. The infrared spectra are decomposed into time courses of characteristic spectral patterns using Multivariate Curve Resolution (MCR). It was found that depending on the applied curing temperature, melamine films with different spectral fingerprints and correspondingly different chemical network structures are formed. The network structures of fully cured resin films are specific for the applied curing temperatures used and cannot simply be compensated by changes in the curing time. For industrial curing processes, this means that cure temperature is the main system determining factor at constant M:F ratio. However, different MF resin networks can be specifically obtained from one and the same melamine resin by suitable selection of the curing time and temperatures profiles to design resin functionality. The spectral fingerprints after short curing time as well as after long curing time reflect the fundamental differences in the thermoset networks that can be obtained with industrial short-cycle and multi-daylight presses.

Characterization of brain tumours requires neuropathological expertise and is generally performed by histological evaluation and molecular analysis. One emerging technique to assist pathologists in future tumour diagnostics is multimodal optical spectroscopy. In the current clinical routine, tissue preprocessing with formalin is widely established and suitable for spectroscopic investigations since degradation processes impede the measurement of native tissue. However, formalin fixation results in alterations of the tissue chemistry and morphology for example by protein cross-linking. As optical spectroscopy is sensitive to these variations, we evaluate the effects of formalin fixation on multimodal brain tumour data in this proof-of-concept study. Nonfixed and formalin-fixed cross sections of different common human brain tumours were subjected to analysis of chemical variations using ultraviolet and Fourier-transform infrared microspectroscopy. Morphological changes were assessed by elastic light scattering microspectroscopy in the visible wavelength range. Data were analysed with multivariate data analysis and compared with histopathology. Tissue type classifications deduced by optical spectroscopy are highly comparable and independent from the preparation and the fixation protocol. However, formalin fixation leads to slightly better classification models due to improved stability of the tissue. As a consequence, spectroscopic methods represent an appropriate additional contrast for chemical and morphological information in neuropathological diagnosis and should be investigated to a greater extent. Furthermore, they can be included in the clinical workflow even after formalin fixation.