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VG-Wort-Vergütungen bei Lesungen: Alle Fakten im Überblick : für Lesungen in Bibliotheken müssen in der Regel Vergütungen an die Verwertungsgesellschaft gezahlt werden ; die Rechtsexperten Arne Upmeier und Eric Steinhauer klären die wichtigsten Fragen
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Three-Dimensional Settling Dynamics of Environmental Microplastics
No full textResolving the three-dimensional settling dynamics of microplastic (MP) particles is essential for developing comprehensive models of MP transport in rivers─both vertically within the water column and laterally across the channel. While previous research has largely examined one-dimensional vertical settling velocities, little is known about the lateral drifting, settling paths, and horizontal velocities of MPs. To address this, we investigated the full three-dimensional settling behavior of environmental MPs collected from rivers and ocean water, as well as from estuarine and ocean sediment. Geometric properties of 127 environmental MPs were quantified by a dynamic particle image analyzer, and their settling trajectories were recorded and reconstructed via a multicamera tracking algorithm. This enabled quantification of a particle’s horizontal drift, tortuosity, amplitude and settling pattern, as well as vertical and horizontal velocities. Results showed that spherical MPs settled with minimal lateral displacement, whereas elongated particles, such as rod- and blade-shaped MPs, displayed pronounced lateral movements, reaching up to 65 times their equivalent diameter and averaging more than twice that of spheres. These dynamics suggest that elongated MPs may have a greater probability for wider lateral dispersion in rivers, increasing their likelihood for interactions with riverbanks and channel boundaries compared to more spherical shaped MPs
Convection Velocities of Passive Scalar and Velocity Fluctuations in Wall-Bounded Turbulence
No full textTaylor’s hypothesis of frozen turbulence is applied to many experimental use cases to
convert time series into spatial field data. To do so, the concept of a convection velocity
is needed, which characterises the velocity at which coherent turbulent structures move
within the considered flow. This thesis uses a definition of convection velocity from the
literature to analyse the convection behaviour of different quantities in wall-bounded
turbulence. Therefore, a deeper understanding of the underlying physical mechanisms is
gained, which can be used to apply Taylor’s hypothesis more sophisticated. The considered
quantities are structures of all three velocity components as well as passive scalar structures
at three different Prandtl numbers. Direct numerical simulations of periodic channels
at three different Reynolds numbers are conducted to generate data. To validate these
data, typical turbulence statistics are retraced, which show good agreement with results
from the literature. Next, a transport equation analysis is conducted, revealing where
and why Taylor’s hypothesis might not be applicable. The results of this analysis are in
good agreement with data from the literature in the case of turbulent velocity structures.
Therefore, trustworthy insights can be gained from the remaining analyses on the behaviour
of passive scalar structures. In the following step, the convection velocities of all structures
considered are inspected regarding their dependency on the wall distance. To validate
these results, known statistics from the literature are used. In addition, new findings
regarding the influence of the Prandtl and Reynolds numbers, different-sized structures,
and physical driving mechanisms are made. Finally, a spectral analysis of the convection
velocity distribution in the Fourier space is performed. The insights resulting from this
provide fundamental information on the physical behaviour, which was shown by the
previous analyses
Optically detected nuclear magnetic resonance of coherent spins in a molecular complex
No full textNuclear magnetic resonance is a powerful tool for applications ranging from chemical analysis to quantum information processing. Achieving optical initialization and detection of molecular nuclear spins promises new opportunities—including improved nuclear magnetic resonance signals at low magnetic field, sensitivity down to the single-molecule level and full access to atomically precise molecular architectures for quantum technologies. Here we report the optical read-out of coherently controlled nuclear spins in a europium-based molecular crystal. By harnessing ultranarrow optical transitions, we achieve the optical initialization and detection of nuclear spin states. Through radio-frequency driving, we address two nuclear quadrupole resonances, characterized by narrow inhomogeneous linewidths and a distinct correlation with the optical transition frequency. We implement Rabi oscillations, spin echo and dynamical decoupling techniques, achieving nuclear spin quantum coherence with a lifetime of up to 2 ms. These results highlight the capabilities of optically detected nuclear magnetic resonance and underscore the promise of molecular nuclear spins for quantum information processing
Data-driven core-collapse supernova multilateration with first neutrino events
No full textA Galactic core-collapse supernova (CCSN) is likely to be observed in neutrino detectors around the world minutes to hours before the electromagnetic radiation arrives. The SuperNova Early Warning System (SNEWS2.0) network of neutrino and dark matter detectors aims to use the relative arrival times of the neutrinos at the different experiments to point back to the supernova so as to facilitate follow-up observation. One of the simplest methods to estimate the CCSN direction is to use the first neutrino events detected through the inverse decay (IBD) process, νe p → eþn. We will consider neutrino detectors sensitive to IBD interactions with low backgrounds. The difference in signal arrival times between a large and a small detector will be biased, however, with the first event at the smaller detector, on average, arriving later than that at the larger detector. This bias can be mitigated by using these first events in a data-driven approach without recourse to simulations or models. The resulting method requires, at minimum, only the times of the first events at most detectors, along with a longer time series of events from one larger detector to act as a reference lightcurve. In this article, we demonstrate this method and its uncertainty estimate using pairs of detectors of different sizes and with different supernova distances. Finally, we use this method to calculate probability skymaps using four detectors currently in operation, Super-Kamiokande, Jiangmen Underground Neutrino Observatory (JUNO), Large Volume Detector (LVD), and SNO+, and show that the calculated probabilities yield appropriate confidence intervals for all supernova directions. The area of the 68% confidence interval varies by distance and direction, but is expected to be a few thousand square degrees. The resulting skymaps should be useful for the multimessenger community as a rapid, initial pointing to follow up on the SNEWS2.0 Galactic CCSN neutrino alert
Scaling-up electro-organic synthesis: challenges and approaches
No full textThe electrosynthetic preparation of organic compounds experiences a strongly increasing attention and evolves into a future methodology. The scalability of these synthetic approaches generated several electrolyzer concepts, including monopolar, bipolar, and rotating electrode setups. With such strategies, scaling into the hectogram and kilogram range is readily viable
Ölmobilität in Haselnusspasten: Einfluss der Inhaltsstoffe und Prozesstechnik
No full textHazelnut pastes consist of sugar, cocoa, milk powder and ground nuts, which are dispersed within a quasi-continuous oil and fat phase mainly composed of hazelnut oil. The mobility of this oil fraction contributes to oil separation on the surface and oil migration within the matrix. The mechanisms underlying these phenomena, as well as the factors influencing them, are not yet fully understood.
The aim of this study is to investigate systematically how compositional and processing parameters affect oil mobility in hazelnut pastes. Specifically, the work examines (1) the effect of different physicochemical properties of oils and fats on oil mobility, (2) oil immobilization induced by solid particles typically present in nut pastes, (3) the influence of grinding and mixing processes on oil mobility in hazelnut pastes, and (4) the immobilization of hazelnut oil within oleogel networks.
The results show that oil mobility is influenced, on the one hand, by the composition of the ingredients – particularly the specific surface area, particle size and -shape, and surface hydrophobicity of the solids –, as well as the viscosity of oils. On the other hand, grinding and mixing conditions have a substantial impact on mobility in nut pastes. The effects of composition and processing cannot be considered independently, as they are closely interrelated. A finer grinding of pure hazelnut pastes increases oil mobility due to the destruction of oleosomes, whereas in hazelnut-sucrose or nougat pastes it leads to a smaller oil mobility as a result of the larger relative surface area and the formation of densely packed structures with entrapped oil. Furthermore, oleogelation represents an effective approach to reduce the mobility of hazelnut oil.
Across all model systems, oil mobility is primarily governed by two mechanisms: adsorption of oil onto surfaces of solids and physical entrapment or geometric hindrance within interparticle voids or densely packed particle structures. The interpretation of oil mobility measurements strongly depends on the investigated material system, the applied measurement method and the considered length scale.
The results of this work contribute to a deeper understanding of the mechanisms governing oil mobility in nut-based systems and provide a scientific basis for optimizing their stability and shelf life
Adapted Feeding Strategies Enable Efficient Growth and Lipid Accumulation Using Untreated Crude Glycerol in Transition Scale with Cutaneotrichosporon oleaginosum ATCC 20509
No full textYeasts such as Cutaneotrichosporon oleaginosum can convert low-value side streams into
single-cell oils with fatty acid profiles comparable to vegetable oils. Crude glycerol (CG), a
byproduct of biodiesel production, offers a cost-effective substrate, but its variable impurity
load often causes strong growth inhibition. In this study, two untreated industrial CG
batches were characterized and evaluated in 2.5 L and 19 L stirred-tank fermentations.
Direct batch cultivation on CG resulted in no measurable growth, whereas an adapted step-
wise feeding strategy effectively mitigated early inhibition and restored biomass formation,
metabolic activity, and lipid accumulation. In 2.5 L cultivations, apparent growth rates up
to 0.51 h−1 and volumetric productivities up to 0.22 g L−1 h−1 were achieved, with lipid
contents of ~30% and oleate-dominated fatty acid profiles. Fatty acid profiles remained
oleate-dominated (~53–55% C18:1). Transition-scale (19 L) repeated-batch fermentations
confirmed process robustness across > 640 h of operation, during which lipid content (~30–
36%) and fatty acid composition (oleate ~51–53%) remained stable despite pronounced
substrate-batch variability and increasing nitrogen limitation. These results demonstrate
that untreated CG can be reliably valorized for lipid production using scalable feeding
strategies without prior detoxification. This closes a gap between laboratory-scale feasi-
bility studies and process-oriented, multi-cycle operation on industrial-grade feedstocks,
confirming that feeding-driven inhibition control can ensure robust performance without
substrate purification