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Diemar, Andreas; Gerth, Uwe; Lahmer, Tom; Teichert, Gerd; Könke, Carsten
Numerische Ermittlung von Zielgrößen und Prozessparametern des Einsatzhärtens unter Berücksichtigung des lokalen Beanspruchungszustandes versagensrelevanter Konstruktionsdetails :
Numerical determination of target values and process parameters of case hardening, taking into account the local stress state of failure-relevant construction details. - In: HTM - journal of heat treatment and materials, ISSN 2194-1831, Bd. 78 (2023), 6, S. 352-368

Through the thermochemical process of case hardening, the local material strength of steel components can be increased. In addition to the increase in stress due to the notch effect, the shape of construction details also has an effect on key component properties after case hardening, such as edge hardness and case hardening depth. The component-related specification of target values for case hardening is currently based on empirical values or expert knowledge. In addition, the effect of design details during case hardening is not taken into account when specifying process parameters in the control and regulation software of case hardening systems. This article presents a concept for the numerical determination of target values and process parameters for case hardening based on the stress state of the component. Compared to the empirically based determination of target values and process parameters for case hardening, the application of the concept makes it possible to adapt the case hardening of components to their stress in the failure range and thus significantly increase the energy and resource efficiency of case hardening.



https://doi.org/10.1515/htm-2023-0023
Hein, Matthias; Saccardi, Francesco
Automotive antenna measurements at VISTA. - In: Reviews of electromagnetics, ISSN 2709-4057, Bd. 2 (2023), S. 17-18
Enthalten in Roadmap paper: Antenna measurement challenges and opportunities, guest editors: Olav Breinbjerg and Manuel Sierra-Castañer

https://doi.org/10.53792/RoE/2023/23003
Bohm, Sebastian; Grunert, Malte; Schwarz, Felix; Runge, Erich; Wang, Dong; Schaaf, Peter; Chimeh, Abbas; Lienau, Christoph
Gold nanosponges: fascinating optical properties of a unique disorder-dominated system. - In: Journal of the Optical Society of America, ISSN 1520-8540, Bd. 40 (2023), 6, S. 1491-1509

Nanoporous gold is a three-dimensional bulk material that is percolated with a random network of nanometer-sized ligaments and made by selective corrosion of bimetallic alloys. It has intriguing geometric, catalytic, and optical properties that have fascinated scientists for many decades. When such a material is made into the form of small, 100-nm-sized particles, so-called nanosponges emerge that offer much flexibility in controlling their geometric, electronic, and optical properties. Importantly, these particles act as an antenna for light that can efficiently localize optical fields on a deep subwavelength scale in certain hotspots at the particle surface. This makes such nanosponges an interesting platform for plasmonic sensing, photocatalysis, and surface-enhanced Raman spectroscopy. Since the optical properties of these nanosponges can be controlled to a large degree by tuning their geometry and/or composition, they have attracted increasing attention in recent years. Here, we provide a concise overview of the current state of the art in this field, covering their fabrication, computational modeling, and specifically the linear and nonlinear optical properties of individual and hybrid nanosponges, for example, plasmon localization in randomly disordered hotspots with a size <10 nm and a long lifetime with an exceptionally high Purcell factor. The resulting nonlinear optical and photoemission properties are discussed for individual and hybrid nanosponges. The results presented have strong implications for further applications of such nanosponges in photonics and photocatalysis.



https://doi.org/10.1364/JOSAB.479739
Nguyen, Thi-Huong; Wang, Hanqing; Chen, Li-Yu; Echtermeyer, Danny; Pliquett, Uwe
Modulating SARS-CoV-2 spike protein reactivity through moderate electric fields: a pathway to innovative therapies. - In: ACS omega, ISSN 2470-1343, Bd. 8 (2023), 48, S. 45952-45960

In the quest for effective COVID-19 treatments and vaccines, traditional biochemical methods have been paramount, yet the challenge of accommodating diverse viral mutants persists. Recent simulations propose an innovative physical strategy involving an external electric field applied to the SARS-CoV-2 spike protein, demonstrating a reduced viral binding potential. However, limited empirical knowledge exists regarding the characteristics of the spike protein after E-field treatment. Our study addresses this gap by employing diverse analytical techniques to elucidate the impact of low/moderate E-field intensity on the binding of the SARS-CoV-2 spike protein to the ACE2 receptor. Through comprehensive analysis, we unveil a substantial reduction in the spike protein binding capacity validated via enzyme-linked immunosorbent assay and quartz crystal microbalance experiments. Remarkably, the E-field exposure induces significant protein structure rearrangement, leading to an enhanced negative surface zeta potential confirmed by dynamic light scattering. Circular dichroism spectroscopy corroborates these structural changes, showing alterations in the secondary protein structures. This study provides insights into SARS-CoV-2 spike protein modification under an E-field pulse, potentially paving the way for nonbiochemical strategies to mitigate viral reactivity and opening avenues for innovative therapeutic and preventive approaches against COVID-19 and its evolving variants.



https://doi.org/10.1021/acsomega.3c06811
Fischer, Gerald; Kofler, Markus; Baumgarten, Daniel
Implementation of N-Interval fourier transform analysis - application to compound action potentials. - In: MethodsX, ISSN 2215-0161, Bd. 11 (2023), 102441, S. 1-10

N-Interval Fourier Transform Analysis (N-FTA) allows for spectral separation of a periodic target signal from uncorrelated background interference. A N-FTA pseudo-code is presented. The spectral resolution is defined by the repetition rate of the near periodic signal. Acceptance criteria for spectral targets were defined such that the probability of accepting false positives is less than 1/1500. Simulated and recorded neural compound action potentials (CAPs) were investigated. Simulated data allowed for comparison with reference solutions demonstrating the stability of N-FTA at conditions being comparable to real world data. Background activity was assessed with small errors. Evoked target components were assessed down to power spectral density being approximately N times below the background level. Validation was completed investigating a measured CAP. In neurophysiological recordings, this approach allows for accurate separation of near periodic evoked activity from uncorrelated background activities for frequencies below 1kHz. • N-FTA allows for spectral separation of a periodic target signal from uncorrelated interference by analyzing a segment containing N target signal repetitions. • A MATLAB implementation of the algorithm is provided along with simulated and recorded data. • N-FTA was successfully validated using simulated and measured data for CAPs.



https://doi.org/10.1016/j.mex.2023.102441
Fiedler, Patrique; Graichen, Uwe; Zimmer, Ellen; Haueisen, Jens
Simultaneous dry and gel-based high-density electroencephalography recordings. - In: Sensors, ISSN 1424-8220, Bd. 23 (2023), 24, 9745, S. 1-12

Evaluations of new dry, high-density EEG caps have only been performed so far with serial measurements and not with simultaneous (parallel) measurements. For a first comparison of gel-based and dry electrode performance in simultaneous high-density EEG measurements, we developed a new EEG cap comprising 64 gel-based and 64 dry electrodes and performed simultaneous measurements on ten volunteers. We analyzed electrode-skin impedances, resting state EEG, triggered eye blinks, and visual evoked potentials (VEPs). To overcome the issue of different electrode positions in the comparison of simultaneous measurements, we performed spatial frequency analysis of the simultaneously measured EEGs using spatial harmonic analysis (SPHARA). The impedances were 516 ± 429 kOhm (mean ± std) for the dry electrodes and 14 ± 8 kOhm for the gel-based electrodes. For the dry EEG electrodes, we obtained a channel reliability of 77%. We observed no differences between dry and gel-based recordings for the alpha peak frequency and the alpha power amplitude, as well as for the VEP peak amplitudes and latencies. For the VEP, the RMSD and the correlation coefficient between the gel-based and dry recordings were 1.7 ± 0.7 μV and 0.97 ± 0.03, respectively. We observed no differences in the cumulative power distributions of the spatial frequency components for the N75 and P100 VEP peaks. The differences for the N145 VEP peak were attributed to the different noise characteristics of gel-based and dry recordings. In conclusion, we provide evidence for the equivalence of simultaneous dry and gel-based high-density EEG measurements.



https://doi.org/10.3390/s23249745
Kurniawan, Mario; Bund, Andreas
Photoelectrochemical water splitting with cuprous oxide. - In: Galvanotechnik, ISSN 0016-4232, Bd. 114 (2023), 11, S. 1396-1398

Enhancing the performance through the implementation of porous structures - an innovative and cost-effective fabrication technique that relies solely on electrodeposition.



Matos Scotti, Fernando; Pudenz, Maximilian; Perrin, Sarah; Siewert, Erwan; Bergmann, Jean Pierre
Heat input control in horizontal lap joint welding through active wire preheating in GMAW-P. - In: Welding in the world, ISSN 1878-6669, Bd. 0 (2023), insges. 12 S.

In gas metal arc welding (GMAW) the arc power, in general, increases when the wire feed speed is increased. Thus, controlling heat input into the workpiece becomes a challenge, especially when trying to increase productivity. Metal transfer modes such as pulsed and controlled short circuit have been successfully applied to allow smooth metal transfer with relatively low energy. The effect of increasing the electrified length of the electrode or decreasing wire diameter in reducing current has been known for years. However, to some extent, this effect is limited to the physical conditions when using a large distance from contact tip to workpiece. To further increase melting efficiency and reduce arc power the torch presented in this paper includes a second electric circuit into GMAW to preheat the wire by ohmic heating before it reaches the main circuit. In this context, the objective of this work was to verify the effects of active wire preheating in GMAW in lap joint case in terms of electric signal behavior, thermal behavior in the plate, and weld bead formation. By increasing the preheating current, significant reduction in arc power was achieved. This reflects on the resulting weld by avoiding molten pool sagging, reducing fused area, silicate formation, and backside oxidation. The reduction in heat input resulted finally in a smaller heat affected zone which had a finer microstructure. In conclusion, the use of active wire preheating in GMAW expands the potential for increasing productivity and controlling heat input into the workpiece.



https://doi.org/10.1007/s40194-023-01654-9
Hack, Jasmin; Jordan, Moritz; Schmitt, Alina; Raru, Melissa; Zorn, Hannes Sönke; Seyfarth, Alex; Eulenberger, Isabel; Geitner, Robert
Ilm-NMR-P31: an open-access 31P nuclear magnetic resonance database and data-driven prediction of 31P NMR shifts. - In: Journal of cheminformatics, ISSN 1758-2946, Bd. 15 (2023), 122, S. 1-12

This publication introduces a novel open-access 31P Nuclear Magnetic Resonance (NMR) shift database. With 14,250 entries encompassing 13,730 distinct molecules from 3,648 references, this database offers a comprehensive repository of organic and inorganic compounds. Emphasizing single-phosphorus atom compounds, the database facilitates data mining and machine learning endeavors, particularly in signal prediction and Computer-Assisted Structure Elucidation (CASE) systems. Additionally, the article compares different models for 31P NMR shift prediction, showcasing the database’s potential utility. Hierarchically Ordered Spherical Environment (HOSE) code-based models and Graph Neural Networks (GNNs) perform exceptionally well with a mean squared error of 11.9 and 11.4 ppm respectively, achieving accuracy comparable to quantum chemical calculations.



https://doi.org/10.1186/s13321-023-00792-y
Chen, Ting; Fu, Banglong; Shen, Junjun; Suhuddin, Uceu F. H. R.; Wiese, Björn; Huang, Yuanding; Wang, Min; Santos, Jorge F. dos; Bergmann, Jean Pierre; Klusemann, Benjamin
Application of novel constrained friction processing method to produce fine grained biomedical Mg-Zn-Ca alloy. - In: Journal of magnesium and alloys, ISSN 2213-9567, Bd. 0 (2023), 0, S. 1-14

In order to obtain Mg alloys with fine microstructures and high mechanical performances, a novel friction-based processing method, name as “constrained friction processing (CFP)”, was investigated. Via CFP, defect-free Mg-Zn-Ca rods with greatly refined grains and high mechanical properties were produced. Compared to the previous as-cast microstructure, the grain size was reduced from more than 1 mm to around 4 µm within 3 s by a single process cycle. The compressive yield strength was increased by 350% while the ultimate compressive strength by 53%. According to the established material flow behaviors by “tracer material”, the plastic material was transported by shear deformation. From the base material to the rod, the material experienced three stages, i.e. deformation by the tool, upward flow with additional tilt, followed by upward transportation. The microstructural evolution was revealed by “stop-action” technique. The microstructural development at regions adjacent to the rod is mainly controlled by twinning, dynamic recrystallization (DRX) as well as particle stimulated nucleation, while that within the rod is related to DRX combined with grain growth.



https://doi.org/10.1016/j.jma.2023.10.007