Zeitschriftenaufsätze ab 2018 bis 2021

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Radivoievych, Aleksandar; Kolp, Benjamin; Grebinyk, Sergii; Prylutska, Svitlana; Ritter, Uwe; Zolk, Oliver; Glökler, Jörn Felix; Frohme, Marcus; Grebinyk, Anna
Silent death by sound: C60 fullerene sonodynamic treatment of cancer cells. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 24 (2023), 2, 1020, S. 1-17

The acoustic pressure waves of ultrasound (US) not only penetrate biological tissues deeper than light, but they also generate light emission, termed sonoluminescence. This promoted the idea of its use as an alternative energy source for photosensitizer excitation. Pristine C60 fullerene (C60), an excellent photosensitizer, was explored in the frame of cancer sonodynamic therapy (SDT). For that purpose, we analyzed C60 effects on human cervix carcinoma HeLa cells in combination with a low-intensity US treatment. The time-dependent accumulation of C60 in HeLa cells reached its maximum at 24 h (800 ± 66 ng/106 cells). Half of extranuclear C60 is localized within mitochondria. The efficiency of the C60 nanostructure’s sonoexcitation with 1 MHz US was tested with cell-based assays. A significant proapoptotic sonotoxic effect of C60 was found for HeLa cells. C60′s ability to induce apoptosis of carcinoma cells after sonoexcitation with US provides a promising novel approach for cancer treatment.

Herrmann, Andreas; Zekri, Mohamed; Maâlej, Ramzi; Rüssel, Christian
The effect of glass structure on the luminescence spectra of Sm3+-doped aluminosilicate glasses. - In: Materials, ISSN 1996-1944, Bd. 16 (2023), 2, 564, S. 1-12

Peralkaline Sm3+-doped aluminosilicate glasses with different network modifier ions (Mg2+, Ca2+, Sr2+, Ba2+, Zn2+) were investigated to clarify the effect of glass composition and glass structure on the optical properties of the doped Sm3+ ions. For this purpose, the Sm3+ luminescence emission spectra were correlated with the molecular structure of the glasses derived by molecular dynamics (MD) simulations. The different network modifier ions have a clear and systematic effect on the peak area ratio of the Sm3+ emission peaks which correlates with the average rare earth site symmetry in the glasses. The highest site symmetry is found for the calcium aluminosilicate glass. Glasses with network modifier ions of lower and higher ionic radii show a notably lower average site symmetry. The symmetry could be correlated to the rare earth coordination number with oxygen atoms derived by MD simulations. A coordination number of 6 seems to offer the highest average site symmetry. Higher rare earth coordination probabilities with non-bridging oxygen result in an increased splitting of the emission peaks and a notable broadening of the peaks. The zinc containing glass seems to play a special role. The Zn2+ ions notably modify the glass structure and especially the rare earth coordination in comparison to the other network modifier ions in the other investigated glasses. The knowledge on how glass structure affects the optical properties of doped rare earth ions can be used to tailor the rare earth absorption and emission spectra for specific applications.

Saeidi, Hamidreza; Mozaffari, Morteza; Ilbey, Serhat; Dutz, Silvio; Zahn, Diana; Azimi, Gholamhassan; Bock, Michael
Effect of europium substitution on the structural, magnetic and relaxivity properties of Mn-Zn ferrite nanoparticles: a dual-mode MRI contrast-agent candidate. - In: Nanomaterials, ISSN 2079-4991, Bd. 13 (2023), 2, 331, S. 1-19

Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn-Zn ferrite (Mn0.6Zn0.4EuxFe2−xO4, x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for x = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high r2 relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to x = 0.15, r1 relaxivity increased significantly. On the contrary, europium substitution decreased r2 relaxivity due to a reduction in saturation magnetization. The ratio of r2/r1 decreased from 152 for the europium-free sample to 11.2 for x = 0.15, which indicates that Mn0.6Zn0.4Eu0.15Fe1.85O4 is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher r1 and lower r2 relaxivities than those of pluronic F127-coated samples.

Zhao, Junping; Wang, Yahui; Qian, Yudan; Jin, Huile; Tang, Xinyue; Huang, Zaimei; Lou, Jiayi; Zhang, Qingcheng; Lei, Yong; Wang, Shun
Hierarchical design of cross-linked NiCo2S4 nanowires bridged NiCo-hydrocarbonate polyhedrons for high-performance asymmetric supercapacitor. - In: Advanced functional materials, ISSN 1616-3028, Bd. 33 (2023), 4, 2210238, S. 1-14

Engineering core-shell materials with rationally designed architectures and components is an effective strategy to fulfill the high-performance requirements of supercapacitors. Herein, hierarchical candied-haws-like NiCo2S4NiCo(HCO3)2 core-shell heterostructure (NiCo2S4@HCs) is designed with NiCo(HCO3)2 polyhedrons being tightly strung by cross-linked NiCo2S4 nanowires. This rational design not only creates more electroactive sites but also suppresses the volume expansion during the charge-discharge processes. Meanwhile, density functional theory calculations ascertain that the formation of NiCo2S4@HCs heterostructure simultaneously facilitates OH− adsorption/desorption and accelerates electron transfer within the electrode, boosting fast and efficient redox reactions. Ex situ X-ray diffraction and Raman measurements reveal that gradual phase transformations from NiCo(HCO3)2 to NiCo(OH)2CO3 and then to highly-active NiCoOOH take place during the cycles. Therefore, NiCo2S4@HCs demonstrates an ultrahigh capacitance of 3178.2 F g−1 at 1 A g−1 and a remarkable rate capability of 2179.3 F g−1 at 30 A g−1. In addition, the asymmetric supercapacitor NiCo2S4@HCs//AC exhibits a high energy density of 69.6 W h kg−1 at the power density of 847 W kg−1 and excellent cycling stability with 90.2% retained capacitance after 10 000 cycles. Therefore, this novel structural design has effectively manipulated the interface charge states and guaranteed the structural integrity of electrode materials to achieve superior electrochemical performances.

Tan, Xinu; Liu, Yushun; Li, Feitao; Qiu, Risheng; Liu, Qing
Formation of nanocrystalline γ-ZrH in Zr-Nb alloy: crystal structure and twinning. - In: Micron, ISSN 1878-4291, Bd. 167 (2023), 103414

In the present work, the lattice parameter and the twins of γ-ZrH hydride in Zr-2.5Nb-1Si were characterized using high resolution electron microscopy. The lattice parameters of γ-ZrH (P42/mmc, Zr2H2 unit cell) is determined to be a= 0.336nm, c=0.508nm. Twinning γ-ZrH hydride ({011}<0̅11> type) is for the first time reported in zirconium alloys, whose orientation relationship with α-Zr is [100]γ-twins // [1̅210]α and (011)γ-twins // (0002)α. The formation process of γ-ZrH twins is also discussed based on a ‘grow-in’ mechanism during the transformation from α-Zr to γ-ZrH hydride.

Sachs, Sebastian; Ratz, Manuel; Mäder, Patrick; König, Jörg; Cierpka, Christian
Particle detection and size recognition based on defocused particle images: a comparison of a deterministic algorithm and a deep neural network. - In: Experiments in fluids, ISSN 1432-1114, Bd. 64 (2023), 2, 21, S. 1-16

The systematic manipulation of components of multimodal particle solutions is a key for the design of modern industrial products and pharmaceuticals with highly customized properties. In order to optimize innovative particle separation devices on microfluidic scales, a particle size recognition with simultaneous volumetric position determination is essential. In the present study, the astigmatism particle tracking velocimetry is extended by a deterministic algorithm and a deep neural network (DNN) to include size classification of particles of multimodal size distribution. Without any adaptation of the existing measurement setup, a reliable classification of bimodal particle solutions in the size range of 1.14 μm–5.03 μm is demonstrated with a precision of up to 99.9 %. Concurrently, the high detection rate of the particles, suspended in a laminar fluid flow, is quantified by a recall of 99.0 %. By extracting particle images from the experimentally acquired images and placing them on a synthetic background, semi-synthetic images with consistent ground truth are generated. These contain labeled overlapping particle images that are correctly detected and classified by the DNN. The study is complemented by employing the presented algorithms for simultaneous size recognition of up to four particle species with a particle diameter in between 1.14 μm and 5.03 μm. With the very high precision of up to 99.3 % at a recall of 94.8 %, the applicability to classify multimodal particle mixtures even in dense solutions is confirmed. The present contribution thus paves the way for quantitative evaluation of microfluidic separation and mixing processes.

Piekarz, Ilona; Sorocki, Jakub; Górska, Sabina; Bartsch, Heike; Rydosz, Artur; Smolarz, Robert; Wincza, Krzysztof; Gruszczynski, Slawomir
High sensitivity and selectivity microwave biosensor using biofunctionalized differential resonant array implemented in LTCC for Escherichia coli detection. - In: Measurement, Bd. 208 (2023), 112473, insges. 8 S.

A novel method for label-free detection of Escherichia coli relying on microwave sensing is proposed. A transmission-type differential resonator array biosensor covered with polyclonal anti-Escherichia coli antibodies is introduced providing a robust response with high sensitivity for detecting bacteria presence due to resonant operation combined. The high selectivity is given by the presence of specific bacteria-binding antibodies. Low-Temperature Co-Fired Ceramics technology is proposed to be used for implementation to take advantage of its quasi-three-dimensional fabrication capability. The proposed sensing structure operates in a frequency range of 4 - 6 GHz with five distinct resonances increasing the probability of bacteria detection presence. The developed sensor was experimentally validated by measurements of various concentrations of Escherichia coli along with measurement of a non-specific high concentration of Lactobacillus rhamnosus LOCK 0919. The obtained results prove the performance and suitability of the proposed biosensor for biomedical applications.

Miegel, Konrad; Fröhlich, Thomas; Pätz, Joachim
Strahlungsfehler bei Lufttemperaturmessungen: Minimierung des Fehlers durch ein neues Referenzsystem und Vergleich mit konventionellen Messsystemen, Tages- und Jahresgang ihres Fehlers in Abhängigkeit von Strahlung und Windgeschwindigkeit :
Radiation error of air temperature measurements: minimization of the error by a new reference system and comparison with conventional measurement systems, diurnal and annual variation of their errors as a function of radiation and wind speed. - In: Technisches Messen, ISSN 2196-7113, Bd. 90 (2023), 1, S. 65-78

The measurement of air temperature is associated with inaccuracies resulting from radiation errors. Liquid thermometers and automatic sensors are therefore housed in screens. Mechanical ventilation also helps to increase the accuracy of readings. Nonetheless, temperature measurements are not completely accurate. This spurred the development of a measuring system that features improved radiation protection and a modified mechanical ventilation system through a new type of screen. Parallel measurements with this new measurement system and two conventional screens of multiple plastic cones were taken at a location in north-east Germany with a temperate climate. Of the two traditional screens, one was ventilated and the other not. Based on previous findings concerning the seasonality of radiation errors, our analysis of their dependency on global radiation and wind speed was focused on the months of May to August, when global radiation is at its strongest. It was found that the not insignificant differences in Δ T\Delta T display a characteristic diurnal variation. With the new measurement system, in comparison with the two conventional measurung systems, the average air temperature of the four surveyed months during daylight hours was 0.43 K and 0.58 K lower. The differences in Δ T\Delta T are greatest not in the middle of the day but when the sun is low in the sky, as radiation is then reflected into the screen. The findings contribute to the understanding of the temporal variability of radiation errors in modern weather stations in dependence on global radiation and wind speed. The technical innovations presented here allow radiation errors to be largely avoided.

Charfi, Bilel; Zekri, Mohamed; Herrmann, Andreas; Damak, Kamel; Maâlej, Ramzi
Atomic scale network structure of a barium aluminosilicate glass doped with different concentrations of rare-earth ions explored by molecular dynamics simulations. - In: Computational materials science, Bd. 218 (2023), 111965

Molecular dynamics (MD) simulation is employed for exploring the coordination of atoms in peralkaline BaO-Al2O3-SiO2 glasses of variable Gd3+ doping concentrations between 1 and 3.8 mol% Gd2O3. For this the MD simulation procedure of inherent structure sampling was used which provides statistically robust information on the local atomic surrounding of the doped rare earth ions. Distributions of Si/Al/Ba/Gd cations in the first, second and third coordination spheres are investigated. Special focus is laid on the effect of Gd3+ doping concentration on the local surrounding of the Gd3+ ions, i. e. rare earth clustering, and general glass structure. The simulations show that SiOAl bonds are preferred in comparison to SiOSi and AlOAl connections with respect to the random model predictions. Deviations from a statistical Si/Al distribution around the BaOp and GdOq polyhedra are observed. The network modifier ions are preferably surrounded by other network modifier ions, rather than by network formers. It is shown that the incorporation of Gd does not affect radial distribution functions, cumulative radial distribution function curves and the coordination sphere of Gd for Gd2O3 doping concentrations of up to 3.8 mol%, i.e. no rare earth clustering is observed. However, increasing Gd2O3 concentrations decrease the number of bridging oxygen and increase the number of non-bridging oxygen (NBO) species in the glass structure. Charge compensation of the additional non-bridging oxygen species is achieved by increasing NBO coordination numbers with Ba2+.

Santhakumaran, Sarmilan; Shardt, Yuri A. W.
Data-driven nonlinear system identification of blood glucose behaviour in Type I diabetics. - In: Control engineering practice, ISSN 1873-6939, Bd. 132 (2023), 105405

Data-driven nonlinear system identification with sparse regression is a promising method to represent nonlinear dynamics in the form of a rigorous model description. Therefore, nonlinear functional structure identification and parameter estimation are performed simultaneously. Classical identification methods require functional structures that are manually derived using process knowledge either from first principles or practical experience. However, the effort required to provide these structures is time-consuming, labour-intensive, and in connection with operational trials in production plants, also associated with high costs. In addition, the latest sparse regression solution for nonlinear system identification does not offer an analytical solution due to the properties of the L1 norm. For this reason, sparse regression with smoothed L1 regularisation is proposed for nonlinear system identification. For this purpose, a nonlinear library function is first constructed based on the extended dynamic mode decomposition theory (eDMD), which contains all possible nonlinear bijective function candidates. For the process description, the most suitable functions with the related weighting parameters are selected using the regularisation properties. The performance of the method is demonstrated using the blood glucose behaviour from Type I Diabetes. The validation of the method is performed for a simulation study with and without noise influence and applied to experimental data of two patients in a Python simulation. It can be shown that the identification is successful for both studies with a performance limit for a signal-to-noise ratio (SNR) of 0.45 (3.46 dB).