Scientific publications

In recent years, there has been increasing interest in studying listening effort. Research on listening effort intersects with the development of active theories of speech perception and contributes to the broader endeavor of understanding speech perception within the context of neuroscientific theories of perception, attention, and effort. Due to the multidisciplinary nature of the problem, researchers vary widely in their precise conceptualization of the catch-all term listening effort. Very recent consensus work stresses the relationship between listening effort and the allocation of cognitive resources, providing a conceptual link to current cognitive neuropsychological theories associating effort with the allocation of selective attention. By linking listening effort to attentional effort, we enable the application of a taxonomy of external and internal attention to the characterization of effortful listening. More specifically, we use a vectorial model to decompose the demand causing listening effort into its mutually orthogonal external and internal components and map the relationship between demanded and exerted effort by means of a resource-limiting term that can represent the influence of motivation as well as vigilance and arousal. Due to its quantitative nature and easy graphical interpretation, this model can be applied to a broad range of problems dealing with listening effort. As such, we conclude that the model provides a good starting point for further research on effortful listening within a more differentiated neuropsychological framework.

3D bioprinting is a booming method to obtain scaffolds of different materials with predesigned and customized morphologies and geometries. In this review we focus on the experimental strategies and recent achievements in the bioprinting of major structural proteins (collagen, silk, fibrin), as a particularly interesting technology to reconstruct the biochemical and biophysical composition and hierarchical morphology of natural scaffolds. The flexibility in molecular design offered by structural proteins, combined with the flexibility in mixing, deposition, and mechanical processing inherent to bioprinting technologies, enables the fabrication of highly functional scaffolds and tissue mimics with a degree of complexity and organization which has only just started to be explored. Here we describe the printing parameters and physical (mechanical) properties of bioinks based on structural proteins, including the biological function of the printed scaffolds. We describe applied printing techniques and cross-linking methods, highlighting the modifications implemented to improve scaffold properties. The used cell types, cell viability, and possible construct applications are also reported. We envision that the application of printing technologies to structural proteins will enable unprecedented control over their supramolecular organization, conferring printed scaffolds biological properties and functions close to natural systems.

This work reports an in vivo approach for identifying the function of biomineralization-related proteins. Synthetic sequences of n16N, OC-17 and perlucin with signal peptides are produced in a novel Gateway expression system for Dictyostelium under the control of the [ecmB] promoter. A fast and easy scanning electron microscopic screening method was used to differentiate on the colony level between interplay effects of the proteins expressed in the extracellular matrix (ECM). Transformed Dictyostelium, which migrated as multicellular colonies on calcite crystals and left their ECM remnants on the surface were investigated by scanning electron microscopy. Calcium minerals with and without phosphorous accumulated very frequently within the matrix of the Dictyostelium colonies when grown on calcite. Magnesium containing phosphorous granules were observed when colonies were exposed on silica. The absence of calcium EDX signals in these cases suggests that the external calcite crystals but not living cells represent the major source of calcium in the ECM. Several features of the system provide first evidence that each protein influences the properties of the matrix in a characteristic mode. Colonies transformed with perlucin produced a matrix with cracks on the length scale of a few microns throughout the matrix patch. For colonies with OC-17, almost no cracks were observed, regardless of the length scale. The non-transformed Dictyostelium (Ax3-Orf+) produced larger cracks. The strategy presented here develops the first step towards an efficient eukaryotic screening system for the combinatorial functionalization of materials by bioengineering in close analogy to natural biomineralization concepts.

This paper reports a rapid HILIC-ESI–MS assay to quantify dipalmitoylphosphatidylcholine (DPPC) as component of lung surfactant for nanosafety studies. The technique was used to investigate the concentration-dependent sorption of DPPC to two-sizes of amorphous SiO2 nanoparticles (SiO2-NPs) in a MeOH:H2O (50/50 v/v) mixture and in cell culture medium. In MeOH:H2O (50/50 v/v), the sorption of DPPC was positively correlated with the nanoparticles concentration. A substantial affinity of small amorphous SiO2-NPs (25 nm) to DPPC standard solution compared to bigger SiO2-NPs (75 nm) was not confirmed for biological specimens. After dispersion of SiO2-NPs in DPPC containing cell culture medium, the capacity of the SiO2-NPs to bind DPPC was reduced in comparison to a mixture of MeOH:H2O (50/50 v/v) regardless from the nanoparticles size. Furthermore, HILIC-ESI–MS revealed that A549 cells internalized DPPC during growth in serum containing medium complemented with DPPC. This finding was in a good agreement with the potential of alveolar type II cells to recycle surfactant components. Binding of lipids present in the cell culture medium to amorphous SiO2-NPs was supported by means of HILIC-ESI–MS, TEM and ICP-MS independently.

In this study, we report p-coumaric acid as novel and effective response marker for indirectly measuring the levels of hypoxia in normal primary bronchial epithelial cells. We developed a simple and rapid technique based on hydrophilic interaction chromatography-electrospray ionization-mass spectrometry (HILIC-ESI–MS). During 168 h of hypoxia without induction of reactive oxygen species (ROS), an almost linear increase of p-coumaric acid levels was observed. We interpret the increasing p-coumaric acid concentrations during hypoxia as a result of cell damage, triggered by reduced co-enzyme Q10 levels, because the oxidative cascade was not able to supply sufficient energy. The HILIC-ESI–MS assay within p-coumaric acid exhibited a linear dynamic range from 60 to 610 ng/μL with correlation coefficient of 0.9998. The precision of the assay was ≤15% RSD and method accuracies between 97 and 108%.

In this study, a simple, rapid and inexpensive approach for the screening of heavy metals with photometric reagents was developed based on porous, anodic aluminium oxide (AAO) films, with detection limits of 0.45 mg L-1 (Co2+), 0.25 mg L-1 (Pb2+) and 0.59 mg L-1 (Ni2+). Noble metal ions Ag+ and Pd2+, as well as Cu2+, formed nanoparticles within the AAO channels during micro-solid phase extraction driven by galvanic electroless displacement followed by UV detection.

We report a simple fast, practical and effective method for the replication of the complex venation patterns of natural leaves into PDMS with accuracy down to a lateral size of 500 nm. Optimising the amount of crosslinker enabled the replication and sealing of the microvascular structures to yield enclosed microfluidic networks. The use of plant leaves as templates for soft lithography was demonstrated across over ten species and included reticulate, arcuate, pinnate, parallel and palmate venation patterns. SEM imaging revealed replication of the plants microscopic and sub-microscopic topography into the PDMS structures, making this method especially attractive for mimicking biological structures for in vitro assays. Flow analysis revealed that the autonomous liquid transport velocity in 1st-order microchannel was 1.5-2.2 times faster than that in the 2nd-order microchannels across three leaf types, with the sorptivity rule surprisingly preserved during self-powered flow through leaf-inspired vascularity from Carpinus betulus.

Anisotrope Partikel sind eine Materialklasse, die es erlaubt, multifunktionelle Eigenschaften in einen partikulär aufgebauten Festkörper zu induzieren. Dadurch können unterschiedliche Funktionen in ein und dasselbe Partikel eingebaut werden, beispielsweise unterschiedliche Polaritäten oder magnetische und optische Eigenschaften. Durch ihre außergewöhnliche Struktur, mit zwei unterschiedlichen Kompartimenten an der Oberfläche, erhielt diese Partikelart den Namen Janus-Partikel. Für die Chemie besteht die Herausforderung in der Synthese solcher Partikel. Es muss dafür gesorgt werden, dass die Reaktionsräume auf der Längenskala der Partikel so differenziert werden, dass es zu einer Anisotropie von Wachstums- oder Funktionalisierungsprozessen kommt. Hierbei spielen insbesondere Reaktionen an Phasengrenzen eine wichtige Rolle. Mittlerweile ist eine Vielzahl an unterschiedlichen Janus-Materialkombinationen bekannt und die ersten Systeme werden in technologischen Anwendungen verwendet.
Anisotropic particles are a materials class, which allows to induce multifunctional properties in a particular solid. This approach presents the possibility that different functions are packed in one particle, for example different surface polarities or optical and magnetic properties. The extraordinary structure of this particle consisting of two different compartments is expressed by the name Janus-Particles. The chemical challenge is the synthetic approach to such particle structures. The reaction rooms on the length scale of the particle have to be differentiated in such a way that an anisotropy of growth and functionalization processes is generated. In this regard reactions at interphases play a major role. Meanwhile many different Janus-material combinations are established and the first systems are transferred to technological processes.

Classical hydrodynamic models predict that infinite work is required to move a three-phase contact line, defined here as the line where a liquid/vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap-shaped polystyrene microdroplets, with nonequilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using in situ atomic force microscopy. We find that slip has a strong influence on the droplet evolutions, both on the transient nonspherical shapes and contact line dynamics. The observations are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition.

We study the effect of long-term habituation signatures of auditory selective attention reflected in the instantaneous phase information of the auditory event-related potentials (ERPs) at four distinct stimuli levels of 60, 70, 80, and 90 dB SPL. The analysis is based on the single-trial level. The effect of habituation can be observed in terms of the changes (jitter) in the instantaneous phase information of ERPs. In particular, the absence of habituation is correlated with a consistently high phase synchronization over ERP trials. We estimate the changes in phase concentration over trials using a Bayesian approach, in which the phase is modeled as being drawn from a von Mises distribution with a concentration parameter which varies smoothly over trials. The smoothness assumption reflects the fact that habituation is a gradual process. We differentiate between different stimuli based on the relative changes and absolute values of the estimated concentration parameter using the proposed Bayesian model.