Zeitschriftenaufsätze ab 2018

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Luo, Wenjun; Xuan, Xinmiao; Shen, Jinfeng; Cheng, Pengfei; Wang, Dong; Schaaf, Peter; Zhang, Zhang; Liu, Junming
High performance photothermal carbon nanotubes/nanostructured hydrogel for solar electricity production and solar water sterilization. - In: Applied surface science, Bd. 643 (2024), 158680

Solar energy is a promising renewable energy source with the potential to contribute to sustainable development. Efficient photothermal conversion is critical for solar energy acquisition and conversion. Here, carbon nanotubes (CNTs) were gelatinized to obtain the nanostructured CNT/hydrogel, and then highly light-absorbing CNT/n-hydrogels with surface texture were obtained by replicating the micrometer structure from the black silicon (b-Si) surface onto CNT/hydrogels by using a PDMS mold. Through the synergistic effect of both surface texture and nanostructures, it demonstrates high efficiency of solar electricity production and solar sterilization. A small thermoelectric (TE) module with an area of 4 × 4 cm2 is integrated with CNT/n-hydrogel absorber for the investigation of photo-thermoelectric conversion. The output power of the CNT/n-hydrogel TE device is 1.42 W•m−2 under 1 sun. And by connecting four devices in series, it has successfully demonstrated for charging mobile phones under two different solar illuminations. This work provides a cost-effective and easy fabrication method for opening up the hydrogel as a photothermal absorber, which is low-cost, reproducible, high-efficiency solar water sterilization and high photothermal conversion efficiency.



https://doi.org/10.1016/j.apsusc.2023.158680
Supreeti, Shraddha; Fischer, Michael; Fritz, Mathias; Müller, Jens
High-resolution patterning on LTCC by transfer of photolithography-based metallic microstructures. - In: International journal of applied ceramic technology, ISSN 1744-7402, Bd. 21 (2024), 2, S. 1180-1190

The growing applications and constant miniaturization of electronic devices and of low-temperature co-fired ceramics (LTCC) in various fields, such as aviation, telecommunications, automotive, satellite communications, and military, have led to an increase in the demand for LTCC. Such prospects arise due to the continuous scaling down of components and high-density interconnection in electronics packaging. This paper reports a technique for the transfer of high-resolution microstructures from silicon substrates to LTCC. In this method, gold and copper patterns were formed by photolithography, electrodeposition, and residual layer stripping on silicon substrate. Lithography provides the opportunity to create and transfer complex patterns for use in several different applications and electroplating enables the use of pure metal for excellent electrical properties. The developed structures were transferred onto a top layer of LTCC tape using hot embossing. Then, the subsequent layers were stacked, laminated, and sintered. A resolution of 1.5 μm after free sintering and 4.5 μm after pressure-assisted sintering was achieved. This distinctive method can be useful for several applications requiring high-resolution and superior electrical properties.



https://doi.org/10.1111/ijac.14569
Zheng, Niannian; Luan, Xiaoli; Shardt, Yuri A. W.; Liu, Fei
Dynamic-controlled principal component analysis for fault detection and automatic recovery. - In: Reliability engineering & system safety, ISSN 1879-0836, Bd. 241 (2024), 109608

To effectively implement the prognostic and health management for industrial processes, a dynamic-controlled principal component analysis (DCPCA) for pattern extraction and deviation diagnosis is proposed under the framework of multivariate statistical modelling, which can accurately detect and automatically rectify the faults. Significantly, the geometric properties of DCPCA are analysed, revealing the spatial structure relationships of different variables and how the data space is partitioned. In addition, the model relationships in DCPCA are explored, including the dynamic characteristics of time-series variables and the algebraic ones of static variables. Based on these results, statistics are derived for monitoring both the dynamic and static relationships of the process, and under the abnormal circumstance, by diagnosing the deviations between the fault pattern and the setpoint, a fault regulator for automatic recovery is designed. The case study of prognostic and health management for an industrial distillation column illustrates the advantages of DCPCA in fully extracting the process dynamics into pattern, as well as fault detection and automatic recovery.



https://doi.org/10.1016/j.ress.2023.109608
Xu, Lin; Han, Ze-feng; Karcher, Christian; Wang, En-gang
Melt flow, heat transfer and solidification in a flexible thin slab continuous casting mold with vertical-combined electromagnetic braking. - In: Journal of iron and steel research, international, ISSN 2210-3988, Bd. 31 (2024), 2, S. 401-415

During continuous casting of steel slabs, the application of electromagnetic braking technology (EMBr) provides an effective tool to influence solidification by controlling the pattern of melt flow in the mold. Thus, the quality of the final product can be improved considerably. A new electromagnetic braking (EMBr) method, named vertical-combined electromagnetic braking (VC-EMBr), is proposed to be applied to a flexible thin slab casting (FTSC) mold. To evaluate the beneficial effects of the VC-EMBr, the melt flow, heat transfer, and solidification processes in the FTSC mold are studied by means of numerical simulations. In detail, a Reynolds-averaged Navier-Stokes turbulence model together with an enthalpy-porosity approach was used. The numerical findings are compared with respective simulations using the traditional Ruler-EMBr. The results demonstrate that the application of the VC-EMBr contributes significantly to preventing relative slab defects. In contrast to the Ruler-EMBr, the additional vertical magnetic poles of the VC-EMBr preferentially suppress the direct impact of jet flow on the narrow face of FSTC mold and considerably diminish the level fluctuation near the meniscus region. For instance, by applying a magnetic flux density of 0.3 T, the maximum amplitude of meniscus deflection reduces by about 80%. Moreover, the braking effect of the VC-EMBr effectively improves the homogeneity of temperature distribution in the upper recirculation region and increases the solidified shell thickness along the casting direction. On this basis, the newly proposed VC-EMBr shows a beneficial effect in preventing relative slab defects for FTSC thin slab continuous casting.



https://doi.org/10.1007/s42243-023-01062-9
Li, Pan-Xin; Luo, Xiao-Hong; Chen, Lu; Song, Jia-Jun; Li, Ben-Wen; Karcher, Christian
Numerical research for the effect of magnetic field on convective transport process of molten salt in Rayleigh-Bénard system. - In: International journal of thermal sciences, ISSN 1778-4166, Bd. 195 (2024), 108605, S. 1-21

The effects of external applied magnetic field on heat and momentum transfer of Rayleigh-Bénard convection in a closed cavity filled with electrically conductive molten salt are investigated by direct numerical simulation. Such arrangements are of strong interest in the context of thermal energy storage systems from renewable resources. To discretize the governing equations, the Chebyshev collocation spectral method is developed. A series of numerical results for 5000 ≤ Ra ≤ 10^6, 5 ≤ Pr ≤ 20 and 0 ≤ Ha ≤ 150 are obtained. First, we conduct two-dimensional numerical simulations to investigate the effect of Pr without and with magnetic field and find that Pr has little influence on heat and momentum transfer. Then, taking Pr as a fixed value of 7 and considering the effects of Ra and Ha, 2D and 3D direct numerical simulations are conducted. From both 2D and 3D numerical results, we conclude that, the heat and momentum transfer are enhanced with Ra at Ha = 0 and the fluid motion is stabilized by magnetic field at Ha 0. More phenomena of heat transfer and fluid flow, together with scaling correlations of Nu ∼ Ra, Nu ∼ Re for Rayleigh-Bénard convection without magnetic field, and, Nu ∼ RaHa and Re ∼ RaHa for Rayleigh-Bénard convection with magnetic field, are revealed under specified ranges of Ra and Ha.



https://doi.org/10.1016/j.ijthermalsci.2023.108605
Grebinyk, Anna; Prylutska, Svitlana; Grebinyk, Sergii; Prylutskyy, Yuriy; Ritter, Uwe; Matyshevska, Olga; Dandekar, Thomas; Frohme, Marcus
Toward photodynamic cancer chemotherapy with C60-Doxorubicin nanocomplexes. - In: Nanomaterials for photodynamics therapy, (2023), S. 489-522

Recent progress in nanotechnology has attracted interest to a biomedical application of the carbon nanoparticle C60 fullerene (C60) due to its unique structure and versatile biological activity. The dual functionality of C60 as a photosensitizer and a drug nanocarrier sets an opportunity to improve the efficiency of chemotherapeutic drugs for cancer cells. Pristine C60 demonstrates time-dependent accumulation with predominant mitochondrial localization in cancer cells. Nanomolar amounts of C60-drug nanocomplexes in 1:1 and 2:1 molar ratios improve the efficiency of cell treatment, complementing it with photodynamic approach. The cooperative enhancement interactions between mechanisms of chemo- and photodynamic therapies contribute to the obtained synergistic effect (namely “1+1>2”). A strong synergy of treatments arising from the combination of C60-mediated drug delivery and C60 photoexcitation indicates that a combination of chemo- and photodynamic treatments with C60-drug nanoformulations could provide a promising synergetic approach for cancer treatment.



https://doi.org/10.1016/B978-0-323-85595-2.00005-0
Walter, Uwe; Brandt, Stephan A.; Förderreuther, Stefanie; Günther, Albrecht; Hansen, Hans-Christian; Haueisen, Jens; Salih, Farid; Weise, David
Recommendations of the German Society for Clinical Neurophysiology and Functional Imaging for the diagnosis of irreversible loss of brain function :
Empfehlungen der Deutschen Gesellschaft für Klinische Neurophysiologie und Funktionelle Bildgebung (DGKN) zur Diagnostik des irreversiblen Hirnfunktionsausfalls. - In: Klinische Neurophysiologie, ISSN 1439-4081, Bd. 54 (2023), 4, S. 221-230

Im Zuge der Fünften Fortschreibung der Richtlinie der Bundesärztekammer zur Feststellung des irreversiblen Hirnfunktionsausfalls, gültig seit September 2022, wurden die Empfehlungen der Deutschen Gesellschaft für Klinische Neurophysiologie und Funktionelle Bildgebung (DGKN) zu den ergänzenden elektrophysiologischen und Doppler-sonografischen Untersuchungen aktualisiert. Die hier präsentierten Empfehlungen der DGKN beinhalten die Indikationen, Voraussetzungen und die Durchführung dieser Zusatzverfahren bei Kindern und Erwachsenen.



https://doi.org/10.1055/a-2069-3379
Lüdge, Kathy;
Photonic reservoir computing for energy efficient and versatile machine learning application. - In: Proceedings of the Royal Society of Victoria, Bd. 135 (2023), 2, S. 38-40

Time-multiplexed reservoir computing is a machine learning concept which can be realised in photonic hardware systems using only one physical node. The concept can be used for various problems, ranging from classification problems to time-series prediction tasks, while being fast and energy efficient. Here, a theoretical analysis of a reservoir computer realised via delay-coupled semiconductor lasers is presented and the role of the internal system time-scales and the bifurcation structure is discussed. It is further shown that optimal performance can be reached by tailoring the coupling delays to the specific memory requirements of the given task.



https://doi.org/10.1071/rs23006
Labus Zlatanovic, Danka; Bergmann, Jean Pierre; Baloš, Sebastian; Janjatoviâc, Petar; Rajnoviâc, Dragan; Šidjanin, Leposava
Influence of strain rate on metallurgical and mechanical properties of friction stir spot welded aluminium joints. - In: Advanced technologies and materials, ISSN 2620-147X, Bd. 48 (2023), 2, S. 37-43

Nowadays, the substitution of copper with aluminium is widely pursued in order to save weight and material costs, for battery components and wire connectors. Additionally, cost reductions can be further enhanced with effective reduction of energy consumption through efficient manufacturing. Therefore, friction stir spot welding as a solid-state welding technique is a potential choice with low energy demands and high joining performances. However, the joining of aluminium and its alloys with solid-state welding techniques is still a challenging task due to a persistent and chemically stable aluminium oxide layer formed at the sheets prior to the welding, due to the reaction between aluminium and atmospheric oxygen. In this paper, the influence of strain rate induced during friction stir spot welding process on the metallurgical, mechanical and electrical properties of friction stir spot welding of AA 5754-H111 was studied. The strain rate was calculated according to the rotational speed of the tool and the effective (average) radius and depth of the stir zone. It was observed that the specimens welded with a lower strain rate endured a 15 % higher average strain failure load compared to the specimens welded at a higher share rate. The microhardness profiles of the specimens obtained at low strain rates imply strain hardening mechanisms in the weld zone, while the microhardness of specimens welded at high strain rates expressed thermal softening. It was also found that the friction welded sheets, regardless of the strain rate, show increased electrical resistance compared to the base material, however, it decreases with an increase in strain rate. Microstructural analysis reveals a stress-induced metallurgical transformation in the narrow zone around the weld-faying interface.



https://doi.org/10.24867/ATM-2023-2-001
Hiller, Benedikt T.; Azzi, Julia L.; Rennert, Mirko
Improvement of the thermo-oxidative stability of biobased poly(butylene succinate) (PBS) using biogenic wine by-products as sustainable functional fillers. - In: Polymers, ISSN 2073-4360, Bd. 15 (2023), 11, 2533, S. 1-23

Biobased poly(butylene succinate) (PBS) represents one promising sustainable alternative to petroleum-based polymers. Its sensitivity to thermo-oxidative degradation is one reason for its limited application. In this research, two different varieties of wine grape pomaces (WPs) were investigated as fully biobased stabilizers. WPs were prepared via simultaneous drying and grinding to be used as bio-additives or functional fillers at higher filling rates. The by-products were characterized in terms of composition and relative moisture, in addition to particle size distribution analysis, TGA, and assays to determine the total phenolic content and the antioxidant activity. Biobased PBS was processed with a twin-screw compounder with WP contents up to 20 wt.-%. The thermal and mechanical properties of the compounds were investigated with DSC, TGA, and tensile tests using injection-molded specimens. The thermo-oxidative stability was determined using dynamic OIT and oxidative TGA measurements. While the characteristic thermal properties of the materials remained almost unchanged, the mechanical properties were altered within expected ranges. The analysis of the thermo-oxidative stability revealed WP as an efficient stabilizer for biobased PBS. This research shows that WP, as a low-cost and biobased stabilizer, improves the thermo-oxidative stability of biobased PBS while maintaining its key properties for processing and technical applications.



https://doi.org/10.3390/polym15112533