Now showing 1 - 10 of 92641
  • 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
    Author Correction: Automated real-time monitoring of human pluripotent stem cell aggregation in stirred tank reactors
    ( 2024-12-01)
    Schwedhelm, Ivo
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    Zdzieblo, Daniela
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    Berger, Constantin
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    Schmitz, Tobias
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    Schuldt, Bernhard
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    Franke, Andre
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    Müller, Franz-Josef
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    Pless, Ole
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    Schwarz, Thomas
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    Wiedemann, Philipp
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    Walles, Heike
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    Hansmann, Jan
    Correction to: Scientific Reportshttps://doi.org/10.1038/s41598-019-48814-w, published online 23 August 2019 This Article contains an error. In the Materials and Methods section, the automated cell counter ‘NucleoCounter®’ and the manufacturer ‘ChemoMetec’ were incorrectly given as ‘Nucelocounter’ and ‘Chemometec’, respectively. "Viable cell concentrations were assessed using an automated cell counting system (Nucelocounter NC-200, Chemometec, Denmark)." should read, “Viable cell concentrations were assessed using an automated cell counting system (NucleoCounter® NC-200TM, ChemoMetec, Denmark).”
  • Publication
    Food for future: Exploring cutting-edge technology and practices in vertical farm
    ( 2024-07-01)
    Erekath, Swathi
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    Schreiner, Monika
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    With the growing urbanized population, vertical farming becomes indispensable in eradicating hunger and ensuring food security for the future. Food security has become a major challenge for the future owing to the scarcity of land, rising global population, urbanization, and polluted soil and water resources. In this scenario, vertical farming as an innovative food production technology caters increased productivity with limited resources and improved carbon footprint. The review begins with a brief introduction to the concept of vertical farming, its opportunities and implications on the economy, environment, and society as a whole, following with an in-depth qualitative analysis of the cutting-edge innovations/technologies are presented in detail. Contrary to the numerous research focusing on mere analysis of economic viability and statistical analysis, the aim is to introduce real cutting-edge technologies that address the challenges of vertical farms such as lack of technical skills or energy requirements. The recent advances of vertical farms includes construction of outer vertical structure and growing shelves using light weight and transparent polymer composites, engineered and tunable LEDs lightings, 3-D printed and recyclable growing substrates, AI-integrated IoTs for environment control, harvesting materials for renewable energy storage etc. Such material innovations with inclusion of AI and robotics transform automated vertical farming into ‘state of the art’ agricultural technology. Production shelf fabricated using UV cured GBOV-glass fiber composite with 60% transparency can overcome the material weight limitation, corrosion, light obstructions etc. associated with the conventional steel shelves. Replacing non-renewable fossil fuels using renewable energy harvested by carbon dots, fluorescent materials, and perovskite solar cells is recommended to minimize the high capital investments associated with energy as well as to reduce the environmental impact. Smart materials such as phase change materials and thermoresponsive windows control the amount of energy expended whereas smart substrate promotes resource management. Application of the newest technology AI in vertical farming facilitates precise control of environment, early pest detection, automation of farming processes, data-driven decision making and precision agriculture. In short, vertical farms utilizing modern innovations of science and technology caters enhanced productivity, improved quality, reduced cost, resource management and sustainability. Hence, automated and sustainable vertical farms promoting global food security and circularity have the potential to transform into burgeoning technology of future.
  • Publication
    Diffusion kinetics and perfusion times in tissue models obtained by bioorthogonal Raman μ-spectroscopy
    ( 2024-06-12)
    Altmaier, Saskia
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    The penetration kinetics of small-molecule compounds like nutrients, drugs, and cryoprotective agents into artificial cell aggregates are of pivotal relevance in many applications, from stem cell differentiation and drug screening through to cryopreservation. Depending on compound and tissue properties as well as aggregate size and shape, the penetration behavior can differ vastly. Here, we introduce bioorthogonal Raman microspectroscopy as a contactless technique to investigate the penetration of various compounds into spheroids, organoids, and other tissue models in terms of diffusion coefficients and perfusion times. We showcase the potential of the method by applying it to the radial perfusion of neural stem cell spheroids with the prevalent cryopreservation additive dimethyl sulfoxide. Employing a diffusion model for spherical bodies, the spectroscopic data were quantitatively analyzed. Perfusion times were obtained for spheroids in the sub-mm region, and interesting findings about the spheroid-size dependence of the diffusion coefficient are reported.
  • Publication
    Towards Improving Accountability in Sensitive-Disclosure Scenarios
    ( 2024-06)
    Matzutt, Roman
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    Wagner, Eric
    Public transparency has become increasingly important to uphold trust in government agencies and private companies alike, e.g., by establishing police accountability and proving abiding to ethical supply chain practices. Oftentimes, however, this public interest conflicts with the need for confidentiality of ongoing processes. In this paper, we investigate these sensitive-disclosure scenarios and the requirements for technical solutions to support the data dissemination in these scenarios. We identify translucent blockchains as a promising building block to provide transparency in sensitive-disclosure scenarios with fine-granular access control.
  • 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
    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
    Utilizing waste heat from data centers with adsorptive heat transformation - Heat exchanger design and choice of adsorbent
    ( 2024-06) ; ;
    Stahlhut, Maximilian
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    Mayer, Thomas
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    Herrmann, Ralph
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    Urbaneck, Thorsten
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    The electricity and water consumption of data centers is growing on a global scale. A shift towards liquid cooled racks in combination with thermally driven cooling can help to reduce the electricity and water demand associated with the necessary heat rejection. To quantify the potential of adsorptive heat transformation devices in reducing the electricity and water demand, the prediction of thermal efficiency, heat flow rates and energy efficiency ratio is required. To this end, a numerical model is newly developed using basic adsorption heat exchanger theory. This model can predict the necessary performance indicators with respect to temperatures and volume flow rates, heat exchanger design and adsorbent. The full performance map of a market-available adsorption chiller (71 points) and own measurements are used for calibration and rigorous validation of the model. An average deviation (experiment vs. calculation) of 8.3 % in terms of thermal efficiency and 7.2 % in terms of heat flow rates is achieved, indicating a very good agreement for a wide range of temperatures. At a moderate liquid cooled rack outlet temperature of 50 °C, a heat rejection temperature of 26 °C and a cold aisle inlet temperature of 18 °C the cooling power of the silica gel reference chiller of 5.3 kW can be increased by 59 % to 8.5 kW at a partial energy efficiency ratio (pumps and control, no fans) of > 20 by assuming MIL-100(Fe) as adsorbent on a flat-tube lamella heat exchanger. The model can be used in subsequent annual system simulations to quantify the savings in electrical power and water consumption, which strongly depend on the ambient conditions.
  • Publication
    Towards Access Control for Machine Learning Embeddings
    ( 2024-06)
    Matzutt, Roman
    In this work, we explore the potential to make embeddings, which are becoming an integral part of machine-learning pipelines, shareable with the general public while providing self-contained access control. To this end, we apply attribute-based encryption and discuss a potential application for supply chain management.
  • Publication
    Precision Glass Molding of Fused Silica Optics
    ( 2024-05-28)
    Karimova, Albina
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    Fused silica glass products have exceptional properties that make them ideal for optical components in cutting-edge technologies. The traditional manufacturing process has limitations in scalability and cost. Glass molding offers a sustainable solution for series production of optical components. However, the transferability of glass molding to mass production is challenging due to high forming temperatures. This research focuses on enabling a high temperature molding process for fused silica optics through material screening, numerical simulation, and real experiments. The findings contribute to the development of a high temperature molding process for mass production.