Robust multi-dimensional model order estimation using LineAr Regression of Global Eigenvalues (LaRGE). - In: IEEE transactions on signal processing, ISSN 1941-0476, Bd. 70 (2022), S. 5751-5764
The efficient estimation of an approximate model order is very important for real applications with multi-dimensional low-rank data that may be corrupted by additive noise. In this paper, we present a novel robust to noise method for model order estimation of noise-corrupted multi-dimensional low-rank data based on the LineAr Regression of Global Eigenvalues (LaRGE). The LaRGE method uses the multi-linear singular values obtained from the HOSVD of the measurement tensor to construct global eigenvalues. In contrast to the Modified Exponential Test (EFT) that also exploits the approximate exponential profile of the noise eigenvalues, LaRGE does not require the calculation of the probability of false alarm. Moreover, LaRGE achieves a significantly improved performance in comparison with popular state-of-the-art methods. It is well suited for the analysis of noisy multidimensional low-rank data including biomedical signals. The excellent performance of the LaRGE method is illustrated via simulations and results obtained from EEG recordings.
https://doi.org/10.1109/TSP.2022.3222737
C60 fullerene attenuates muscle force reduction in a rat during fatigue development. - In: Heliyon, ISSN 2405-8440, Bd. 8 (2022), 12, e12449, S. 1-9
C60 fullerene (C60) as a nanocarbon particle, compatible with biological structures, capable of penetrating through cell membranes and effectively scavenging free radicals, is widely used in biomedicine. A protective effect of C60 on the biomechanics of fast (m. gastrocnemius) and slow (m. soleus) muscle contraction in rats and the pro- and antioxidant balance of muscle tissue during the development of muscle fatigue was studied compared to the same effect of the known antioxidant N-acetylcysteine (NAC). C60 and NAC were administered intraperitoneally at doses of 1 and 150 mg kg−1, respectively, daily for 5 days and 1 h before the start of the experiment. The following quantitative markers of muscle fatigue were used: the force of muscle contraction, the level of accumulation of secondary products of lipid peroxidation (TBARS) and the oxygen metabolite H2O2, the activity of first-line antioxidant defense enzymes (superoxide dismutase (SOD) and catalase (CAT)), and the condition of the glutathione system (reduced glutathione (GSH) content and the activity of the glutathione peroxidase (GPx) enzyme). The analysis of the muscle contraction force dynamics in rats against the background of induced muscle fatigue showed, that the effect of C60, 1 h after drug administration, was (15-17)% more effective on fast muscles than on slow muscles. A further slight increase in the effect of C60 was revealed after 2 h of drug injection, (7-9)% in the case of m. gastrocnemius and (5-6)% in the case of m. soleus. An increase in the effect of using C60 occurred within 4 days (the difference between 4 and 5 days did not exceed (3-5)%) and exceeded the effect of NAC by (32-34)%. The analysis of biochemical parameters in rat muscle tissues showed that long-term application of C60 contributed to their decrease by (10-30)% and (5-20)% in fast and slow muscles, respectively, on the 5th day of the experiment. At the same time, the protective effect of C60 was higher compared to NAC by (28-44)%. The obtained results indicate the prospect of using C60 as a potential protective nano agent to improve the efficiency of skeletal muscle function by modifying the reactive oxygen species-dependent mechanisms that play an important role in the processes of muscle fatigue development.
https://doi.org/10.1016/j.heliyon.2022.e12449
Structure and origin of antiphase domains and related defects in thin GaP epilayers on As-modified Si(100). - In: Crystal growth & design, ISSN 1528-7505, Bd. 22 (2022), 12, S. 7040-7049
We study the origin and formation of antiphase domains (APDs) and related defects in 7 nm thin, lattice-matched GaP buffer layers deposited by metal-organic chemical vapor deposition (MOCVD) on well-defined, nearly single-domain, double-layer stepped, low-miscut Si(100) substrates obtained by specific treatment with arsenic. Using dark-field imaging modes in low-energy electron microscopy (LEEM), the minority reconstruction domains of Si(100):As and the APDs of the deposited GaP epilayer are identified, quantified, and compared. We show that residual (2x1)-reconstructed terraces of the minority domain on the Si substrate cause the formation of APDs and that the fraction of the minority domain of the substrate (≅0.07) entails a comparable fraction of APDs in thin GaP epilayers. The topographies of APDs are revealed by atomic force microscopy (AFM) and by scanning tunneling microscopy (STM). We observe two very different APD-related defects in the GaP epilayer, both pinned to residual monolayer steps of the substrate. GaP growth on minority domain terraces with widths in the range of 40-100 nm gives rise to APDs of comparable lateral dimensions. Minority domain terraces of the substrate with widths <20 nm cause the formation of 7-20 nm wide trenches in the GaP layer with rampart-like mounds along their rims. Using nanoscale Auger electron spectroscopy (AES), we provide evidence that these trenches extend through the GaP layer down to the exposed, uncovered Si substrate. We conclude that nucleation of GaP on small minority domain terraces is largely inhibited as most Ga and P atoms deposited on these terraces diffuse across the domain boundary and side walls of emerging trenches to adjacent majority domain terraces where they form the observed mounds. Nucleation of GaP does take place on minority domain terraces with widths ≥40 nm and leads to the growth of APDs.
https://doi.org/10.1021/acs.cgd.2c00697
Methodology for virtual prediction of vehicle-related particle emissions and their influence on ambient PM10 in an urban environment. - In: Atmosphere, ISSN 2073-4433, Bd. 13 (2022), 11, 1924, S. 1-14
As a result of rising environmental awareness, vehicle-related emissions such as particulate matter are subject to increasing criticism. The air pollution in urban areas is especially linked to health risks. The connection between vehicle-related particle emissions and ambient air quality is highly complex. Therefore, a methodology is presented to evaluate the influence of different vehicle-related sources such as exhaust particles, brake wear and tire and road wear particles (TRWP) on ambient particulate matter (PM). In a first step, particle measurements were conducted based on field trials with an instrumented vehicle to determine the main influence parameters for each emission source. Afterwards, a simplified approach for a qualitative prediction of vehicle-related particle emissions is derived. In a next step, a virtual inner-city scenario is set up. This includes a vehicle simulation environment for predicting the local emission hot spots as well as a computational fluid dynamics model (CFD) to account for particle dispersion in the environment. This methodology allows for the investigation of emissions pathways from the point of generation up to the point of their emission potential.
https://doi.org/10.3390/atmos13111924
High adsorption graphene oxide prepared by graphite anode from spent lithium-ion batteries for methylene blue removal. - In: Batteries, ISSN 2313-0105, Bd. 8 (2022), 11, 249, S. 1-13
Limited by the service life, a large amount of spent lithium-ion batteries (LIBs) have been produced in recent years. Without proper disposal, spent LIBs can cause environmental pollution and waste of resources. In this paper, we focus on the recycling of the graphite anode (GA) in spent LIBs. GAs from spent LIBs were converted to graphene oxide (GO) through a modified Hummers method. Then the prepared GO was applied to absorb methylene blue in dyeing wastewater under different reaction conditions. The experimental results indicate that GO can quickly and effectively adsorb methylene blue, which also exhibits thermal stability. The maximum adsorption capacity and removal rate are about 833.11 mg/g and 99.95%, respectively. The adsorption kinetics and isotherms were investigated; the adsorption process of GO is more consistent with the pseudo-second-order adsorption kinetic model while the isotherm is close to the Langmuir isotherm. This study is of great significance for the economy and environment. The reaction can turn waste into wealth and is a win-win approach for both spent LIBs recycling and dyeing wastewater cleaning.
https://doi.org/10.3390/batteries8110249
Optical detection of void formation mechanisms during impregnation of composites by UV-reactive resin systems. - In: Journal of composites science, ISSN 2504-477X, Bd. 6 (2022), 11, 351, S. 1-15
During the impregnation of reinforcement fabrics in liquid composite molding processes, the flow within fiber bundles and the channels between the fiber bundles usually advances at different velocities. This so-called “dual-scale flow” results in void formation inside the composite material and has a negative effect on its mechanical properties. Semi-empirical models can be applied to calculate the extent of the dual-scale flow. In this study, a methodology is presented that stops the impregnation of reinforcement fabrics at different filling levels by using a photo-reactive resin system. By means of optical evaluation, the theoretical calculation models of the dual-scale flow are validated metrologically. The results show increasingly distinct dual-scale flow effects with increasing pressure gradients. The methodology enables the measurability of microscopic differences in flow front progression to validate renowned theoretical models and compare simulations to measurements of applied injection processes.
https://doi.org/10.3390/jcs6110351
High-frequency contactless sensor for the detection of heparin-induced thrombocytopenia antibodies via platelet aggregation. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 23 (2022), 22, 14395, S. 1-13
Heparin-induced thrombocytopenia (HIT), a severe autoimmune disorder, occurs in patients undergoing heparin therapy. The presence of platelet-activating antibodies against platelet factor 4/Heparin in the blood confirms patients suffering from HIT. The most widely used methods for HIT diagnosis are immunoassays but the results only suit to rule out HIT as the assays provide only around 50% specificity. To confirm HIT, samples with positive results in immunoassays are retested in functional assays (>98% specificity) that track platelet-activating antibodies via platelet aggregation. However, the protocols in functional assays are either time-consuming (due to the requirement of the detection of serotonin release) or require highly trained staff for the visualization of platelets. Here, we applied a cheap and easy-to-use contactless sensor, which employs high-frequency microwaves to detect the changes in the resonant frequency caused by platelet aggregation/activation. Analysis of change in conductivity and permittivity allowed us to distinguish between HIT-like (KKO) and non-HIT-like (RTO) antibodies. KKO caused a stronger reduction of conductivity of platelet samples than RTO. Our results imply that the high-frequency contactless sensor can be a promising approach for the development of a better and easier method for the detection of HIT.
https://doi.org/10.3390/ijms232214395
Drug delivery with a pH-sensitive star-like dextran-graft polyacrylamide copolymer. - In: Nanoscale advances, ISSN 2516-0230, Bd. 4 (2022), 23, S. 5077-5088
The development of precision cancer medicine relies on novel formulation strategies for targeted drug delivery to increase the therapeutic outcome. Biocompatible polymer nanoparticles, namely dextran-graft-polyacrylamide (D-g-PAA) copolymers, represent one of the innovative non-invasive approaches for drug delivery applications in cancer therapy. In this study, the star-like D-g-PAA copolymer in anionic form (D-g-PAAan) was developed for pH-triggered targeted drug delivery of the common chemotherapeutic drugs - doxorubicin (Dox) and cisplatin (Cis). The initial D-g-PAA copolymer was synthesized by the radical graft polymerization method, and then alkaline-hydrolyzed to get this polymer in anionic form for further use for drug encapsulation. The acidification of the buffer promoted the release of loaded drugs. D-g-PAAan nanoparticles increased the toxic potential of the drugs against human and mouse lung carcinoma cells (A549 and LLC), but not against normal human lung cells (HEL299). The drug-loaded D-g-PAAan-nanoparticles promoted further oxidative stress and apoptosis induction in LLC cells. D-g-PAAan-nanoparticles improved Dox accumulation and drugs’ toxicity in a 3D LLC multi-cellular spheroid model. The data obtained indicate that the strategy of chemotherapeutic drug encapsulation within the branched D-g-PAAan nanoparticle allows not only to realize pH-triggered drug release but also to potentiate its cytotoxic, prooxidant and proapoptotic effects against lung carcinoma cells.
https://doi.org/10.1039/D2NA00353H
Three mechanisms of room temperature dynamic nuclear polarization occur simultaneously in an ionic liquid. - In: Physical chemistry, chemical physics, ISSN 1463-9084, Bd. 24 (2022), 44, S. 27004-27008
Dynamic nuclear polarization is a versatile approach to increasing the sensitivity of NMR measurements and is achieved by any of four different mechanisms which dominate for either liquids or solids, depending on temperature and radical density. In this work, we unequivocally demonstrate for the first time the coexistence, at a comparable magnitude, of several mechanisms, namely the Overhauser effect, solid effect, and cross-effect/thermal mixing in a viscous ionic liquid at ambient temperatures.
https://doi.org/10.1039/D2CP03437A
Abscheidung von Aluminiumlegierungen aus ionischen Flüssigkeiten. - In: Galvanotechnik, ISSN 0016-4232, Bd. 113 (2022), 10, S. 1299-1304
Umweltfreundliche Schichten aus Aluminiumlegierungen werden gegenüber Schichten aus bedenklichen Metallen wie Cadmium zunehmend interessanter. Allerdings können sie mittels galvanischer Verfahren nur aus aprotischen Elektrolyten, wie ionischen Flüssigkeiten, abgeschieden werden. Um eine hohe Prozessstabilität zu erzielen, können Multianoden eingesetzt werden.