Now showing 1 - 10 of 90699
  • Publication
    Impedance-based in vitro eye irritation testing enables the categorization of diluted chemicals
    ( 2024-12)
    Weissinger, Hannah
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    Knetzger, Nicola
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    Cleve, C.
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    Products containing chemicals with eye irritation potential need to be labeled with the respective hazard symbol. To avoid the testing of numerous dilutions of chemicals on animals, their labeling is directed by a theoretical approach. In this report, a previously described in vitro tissue model of the cornea based on human epithelial cells was used for eye irritation testing of dilutions. As a sensitive and non-destructive method to analyze the barrier function of the epithelium, impedance spectroscopy was applied. Moreover, the morphology and viability of the epithelial models were assessed. We tested four chemicals that, neatly, cause severe damage to the eye: tetrahydrofuran, acetic acid, diethylethanolamine, and benzalkonium chloride. With our test method, we were able to determine the concentrations of the chemicals which are critical for the integrity of the cornea. The threshold was < 0.1% for the most and > 5% for the least toxic substance. The described test system is not only an alternative for animal models but also for the theoretical examination of the hazard potential of diluted chemicals. By using the advantages of tissue engineering and non-destructive analysis tools, we can achieve more precise and safer labeling of the eye irritation potential of products.
  • Publication
    Correlation between laboratory and outdoor soiling experiments with anti-soiling coatings
    ( 2024-06-01)
    Khan, Muhammad Zahid
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    Abuelseoud, Ahmed
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    Lange, Katja
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    Willers, Guido
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    Bahattab, Mohammed A.
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    Qasem, Hussam
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    Gottschalg, Ralph
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    Dust deposition on PV module surfaces is a complex issue influenced by various factors such as weather conditions, dust composition, and surface properties. Outdoor soiling experiments experience fluctuations in environmental conditions, leading to natural inconsistencies and difficulties in reproducibility. On the other hand, laboratory experiments can be conducted in a well-controlled environment and provide rapid results. This study aims to analyze and correlate outdoor and indoor soiling experiments using different anti-soiling coated glass samples. The outdoor experiments, conducted over a year at eight locations in Saudi Arabia, revealed significant variations in soiling behaviour. These were evaluated by assessing light transmission loss through optical transmission analysis. Indoor experiments were conducted in a controlled soiling test chamber and analyzed by optical microscopy to replicate the outdoor behaviour observed with different coating types. Dry laboratory tests followed by wind blow tests showed a strong correlation (Average Pearson r = 0.65) with outdoor soiling results for most locations. In contrast, heavy dew tests showed an anti-correlation with the outdoor soiling results. Therefore, it was also concluded that the resuspension is the primary removal mechanism affecting the performance of the Anti-Soiling Coatings (ASCs) in the dry environments.
  • Publication
    Freeze-thaw, chloride penetration and carbonation resistance of natural and recycled aggregate concrete containing rice husk ash as replacement of cement
    ( 2024-06-01)
    Ma, Wenzhuo
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    Lv, Bodong
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    Wang, Yutong
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    Huang, Liang
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    This study investigated the effect of using rice husk ash (RHA) as replacement of cement (i.e., replacement ratios of 0%, 10%, 20% and 30%) on the durability of natural aggregate concrete (NAC) and recycled aggregate concrete (RAC). We examined the freeze-thaw resistance, chloride penetration resistance, and carbonation resistance of NAC and RAC (with 50% recycled coarse aggregate replacement ratio). It was found that during the freeze-thaw process, both NAC and RAC showed an overall weight increase, which was further enhanced by the addition of RHA. Meanwhile, the compressive strength of NAC was reduced more obviously than that of RAC after 100 freeze-thaw cycles. A replacement of 10% cement with RHA resulted in larger reduction in strength loss for NAC (by 36%) compared to RAC (by 4%). As the RHA replacement ratio increased, the chloride penetration resistance of RACs was improved more rapidly than that of NACs, and the difference in the total charge passed between NACs and RACs also decreased considerably. In addition, an increase in the RHA replacement ratio led to an increase in the carbonation coefficient of NAC. Conversely, in the case of RAC, the carbonation coefficient displayed an initial decrease at a 10% RHA replacement ratio, followed by a subsequent upward trend, indicating a positive impact of RHA on preventing carbonation for RAC.
  • Publication
    Adhesion strength of ductile thin film determined by cross-sectional nanoindentation
    Cross-sectional nanoindentation (CSN) is a powerful tool for measuring the adhesion strength of thin films. However, a quantitative assessment of interfacial properties for metal thin films on brittle substrates remains a challenge due to thin film ductility. In this work, we present a hierarchical analysis method to account for plastic dissipation during delamination. According to our observations, the CSN-induced wedge geometry is more complex than what is currently presented in literature. Therefore, we develop a three-dimensional finite element (FE) modelling strategy to simulate CSN-induced delamination. Furthermore, we present the mode mixity distribution during CSN measurement based on our simulation results. We find that a purely experimental assessment of adhesion strength by CSN for ductile thin films is imprecise due to the adhesion strength-dependent stress-state in this characterization technique. By using our combined experimental and numerical approach, the adhesion strength of EBPVD-deposited Al thin film on SiO2/Si substrate is determined as 0.577 J/m2 and an additional 20 nm thick Ti adhesion layer enhances its adhesion strength to 16.4 J/m2.
  • Publication
    Short-term test for the toxicogenomic assessment of ecotoxic modes of action in Myriophyllum spicatum
    ( 2024-05-10)
    Hanfland, Jost
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    Lousberg, Joëlle
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    Ringbeck, Benedikt
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    In environmental risk assessment of substances, the 14-day growth inhibition test following OECD test guideline 239 is employed to assess toxicity in the macrophyte Myriophyllum spicatum. Currently, this test evaluates physiological parameters and does not allow the identification of the mode of action (MoA) by which adverse effects are induced. However, for an improved ecotoxicity assessment of substances, knowledge about their ecotoxic MoA in non-target organisms is required. It has previously been suggested that the identification of gene expression changes can contribute to MoA identification. Therefore, we developed a shortened three-day assay for M. spicatum including the transcriptomic assessment of global gene expression changes and applied this assay to two model substances, the herbicide and photosynthesis inhibitor bentazone and the pharmaceutical and HMG-CoA reductase inhibitor atorvastatin. Due to the lack of a reference genome for M. spicatum we performed a de novo transcriptome assembly followed by a functional annotation to use the toxicogenomic results for MoA discrimination. The gene expression changes induced by low effect concentrations of these substances were used to identify differentially expressed genes (DEGs) and impaired biological functions for the respective MoA. We observed both concentration-dependent numbers and differentiated patterns of DEGs for both substances. While bentazone impaired genes involved in the response to reactive oxygen species as well as light response, and also genes involved in developmental processes, atorvastatin exposure led to a differential regulation of genes related to brassinosteroid response as well as potential metabolic shifts between the mevalonate and methyl erythritol 4-phosphate pathway. Based on these responses, we identified biomarker candidates for the assessment of MoA in M. spicatum. Utilizing the shortened assay developed in this study, the investigation of the identified biomarker candidates may contribute to the development of future MoA-specific screening approaches in the ecotoxicological hazard prediction using aquatic non-standard model organisms.
  • Publication
    Results of an international interlaboratory study on dioxin-like activities in drinking-, river surface- and wastewater using DR CALUX bioassay
    ( 2024-04-10)
    Behnisch, Peter Alexander
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    Besselink, Harrie
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    Suzuki, Go
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    Buchinger, Sebastian
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    Reifferscheid, Georg
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    Lukas, Marcus
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    Wollenweber, Marc
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    Wollenweber, Simone
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    Hollert, Henner
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    Kunisue, Tatsuya
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    Tue Nguyen, Minh
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    Alijagic, Andi
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    Larsson, Maria
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    Engwall, Magnus
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    Ohno, Kayo
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    Brouwer, Abraham
    Aquatic animals and consumers of aquatic animals are exposed to increasingly complex mixtures of known and as-yet-unknown chemicals with dioxin-like toxicities in the water cycle. Effect- and cell-based bioanalysis can cover known and yet unknown dioxin and dioxin-like compounds as well as complex mixtures thereof but need to be standardized and integrated into international guidelines for environmental testing. In an international laboratory testing (ILT) following ISO/CD 24295 as standard procedure for rat cell-based DR CALUX un-spiked and spiked extracts of drinking-, surface-, and wastewater were validated to generate precision data for the development of the full ISO-standard. We found acceptable repeatability and reproducibility ranges below 36 % by DR CALUX bioassay for the tested un-spiked and spiked water of different origins. The presence of 17 PCDD/Fs and 12 dioxin-like PCBs was also confirmed by congener-specific GC-HRMS analysis. We compared the sum of dioxin-like activity levels measured by DR CALUX bioassay (expressed in 2,3,7,8-TCDD Bioanalytical Equivalents, BEQ; ISO 23196, 2022) with the obtained GC-HRMS chemical analysis results converted to toxic equivalents (TEQ; van den Berg et al., 2013).
  • Publication
    Speicherzugriffsgeleitetes Fuzzing mit Zugriffspositionsanalyse
    ( 2024-04-01)
    Bürger, Thomas
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    Kolvenbach, Philipp
  • Publication
    Managing artificial intelligence applications in healthcare: Promoting information processing among stakeholders
    ( 2024-04)
    Hofmann, Peter
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    Lämmermann, Luis
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    AI applications hold great potential for improving healthcare. However, successfully operating AI is a complex endeavor requiring organizations to establish adequate management approaches. Managing AI applications requires functioning information exchange between a diverse set of stakeholders. Lacking information processing among stakeholders increases task uncertainty, hampering the operation of AI applications. Existing research lacks an understanding of holistic AI management approaches. To shed light on AI management in healthcare, we conducted a multi-perspective literature analysis followed by an interview study. Based on the organizational information processing theory, this paper investigates AI management in healthcare from an organizational perspective. As a result, we develop the AI application management model (AIAMA) that illustrates the managerial factors of AI management in healthcare and its interrelations. Furthermore, we provide managerial practices that improve information processing among stakeholders. We contribute to the academic discourse by providing a conceptual framework that increases the theoretical understanding of AI's management factors and understanding of management interrelations. Moreover, we contribute to practice by providing management practices that promote information processing and decrease task uncertainty when managing AI applications in healthcare.
  • Publication
    Microwave-based removal of polyurethane and epoxy floor coatings
    ( 2024-04)
    Ruf, Maximilian
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    Hillebrand, Georg
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    Schneider, Jan-Pierre
    A new debonding technique based on microwave stimulation is being investigated in epoxy and polyurethane floor coatings by combining specific microwave absorbers with temperature-induced blowing agents. Current methods, including mechanical processes such as grinding, typically produce materials with multiple fractions, impeding recycling and the establishment of a circular economy. The microwave method facilitates mono-fraction materials and enhances accessibility to commonly used recycling techniques, particularly in solvolytic processes such as polyurethane recycling. Consequently, a standard two-layer coating system is used, consisting of an epoxy primer and a polyurethane overlay. Various microwave absorbers, such as carbon black and carbon fibres, as well as blowing agents based on thermally expanding particles are investigated. The influence of the additives on the thermo-mechanical properties is studied to identify suitable combinations. The modified materials are later evaluated for their mechanical properties. Two microwave antennas, operating at a frequency of 2.45 GHz and power of 1 kW, are used and compared to activate the modified coating systems. The technology has been successfully integrated into the formulation to allow mono-fraction recovery of the materials. No significant negative effects on material quality were observed. However, due to the extended processing time required for the debonding, further optimisation is necessary. Nevertheless, the feasibility of utilising a laboratory-based microwave approach has been substantiated.
  • Publication
    Recovery of Cerium from Automotive Catalytic Converters
    ( 2024-03-24) ;
    Fehn, Thomas
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    Berninger, Burkhard
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    Kunz, Werner
    Platinum group metals (PGM) and cerium as one of the rare-earth elementsare considered as critical raw materials, thus their recycling and re-use is ofutmost importance. Among the PGMs, platinum (Pt), palladium (Pd), andrhodium (Rh) are the basic and most valuable metals used in catalytic con-verters. Due to the high price of PGMs, there are already recycling routes inEurope and especially in Germany. For PGM and rare-earth elements, re-search is focusing on greener, plain recovery techniques, which utilize milderreagents, offer better energy efficiency, and replace the existing recyclingroutes. In this work, a hydrometallurgical process is proposed to add ahydrometallurgy method to the mostly pyrometallurgical industrial recyclingroutes, resulting in recovery rates for cerium and PGMs of 63.21% and only1.03% with sulfuric acid, respectively. With hydrochloric acid, the leachingefficiency for cerium is even lower, and for PGM it is comparable. In themethod proposed in the present paper, the main PGMs remain in monolithsand can be recycled in existing recycling routes like pyrometallurgical recycling.