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Parabolic trough collector (PTC) systems, often deployed in arid regions, are vulnerable to dust accumulation (soiling), which reduces mirror reflectivity and energy output. This study presents a physically based soiling forecast algorithm (SFA) designed to estimate soiling levels. The model was calibrated and validated using three meteorological data sources—numerical forecasts (YR), METAR observations, and on-site measurements—from a PTC facility in Limassol, Cyprus. Field campaigns covered dry, rainy, and red-rain conditions. The model demonstrated robust performance, particularly under dry summer conditions, with normalized root mean square errors (NRMSE) below 1%. Sedimentation emerged as the dominant soiling mechanism, while the contributions of impaction and Brownian motion varied according to site-specific environmental conditions. Under dry deposition conditions, the reflectivity change rate during spring and autumn was approximately twice that of summer, indicating a need for more frequent cleaning during transitional seasons. A red-rain event resulted in a pronounced drop in reflectivity, showcasing the model’s ability to capture abrupt soiling dynamics associated with extreme weather episodes. The proposed SFA offers a practical, adaptable tool for reducing soiling-related losses and supporting seasonally adjusted maintenance strategies for solar thermal systems.
Cardiovascular diseases require fast and precise treatment, often involving angiography for diagnosis and intervention. However, training in angiographic procedures often entails exposure to ionizing radiation, which carries inherent risks. To reduce this exposure and enhance training realism, we developed AngioSim—a novel augmented-reality angiography simulation system combined with a vascular silicone simulator. This study evaluates the realism, effectiveness, and potential benefits of AngioSim for neurointerventional training. AngioSim was tested during neurointerventional training sessions with 24 physicians at RWTH Aachen University Hospital. Participants completed a questionnaire assessing realism, usefulness, and preferences compared to other simulators using a Likert scale. Responses were converted to binary categories and McNemar tests were applied for paired comparisons. A total of 92% of physicians rated guidewire and catheter visibility during fluoroscopy as sufficient, while 86% found RM and DSA simulations realistic. AngioSim was preferred over camera-based silicone simulators by 93%, and 96% of physicians rated it necessary for training—significantly more than other simulators (p < 0.05). These results demonstrate the high acceptance and perceived realism of the system and suggest that AngioSim offers advantages over existing training methods. AngioSim offers a realistic, cost-effective, and radiation-free training solution while maintaining the benefits of silicone models. It showed high utility for training purposes, making it a promising addition to neurointerventional programs.
Background: The aim of this study was to assess the agreement between different analysis protocols for the determination of retinal vessel dilation response to flicker light (FL) and its relation to static and metabolic parameters of retinal vessels in healthy subjects.
Methods: In total, 24 right eyes of 24 healthy controls (mean age: 36.04 ± SD 14.4 years) who underwent dynamic and static retinal diameter and oxygen saturation measurements on a Retinal Vessel Analyzer (RVA, Imedos, Jena, Germany) were included. Using repeated video analyses, responses to FL were measured with RVA. These measurements were conducted at three specific retinal locations: within the superotemporal area—within a distance of less than one optic disk (OD) diameter to optic nerve head (ONH) (group 1); greater than one OD diameter to ONH (group 2); and areas near the ONH within the VesselMap region (group 3). For comparability, the static and oxygen saturation parameters were also calculated in the superotemporal peripapillary area using the VesselMap tool of the RVA and were evaluated in relation to the corresponding dynamic area (group 3).
Results: In all groups, the vascular FL response of arteries was less pronounced compared to venules (p = 0.0014). Even though FL responses (mean ± SD: FL-A; FL-V) in group 1 were more pronounced (3.36 ± 2.31; 4.42 ± 1.69) compared to those in group 2 (2.97 ± 2.40; 4.08 ± 1.55) and group 3 (2.84 ± 2.29; 4.21 ± 2.03), they did not reach statistically significant values. The mean flicker response of venules (VDil) in all groups showed negative correlations to the corresponding static parameter: central retinal venous equivalent (CRV) (r = −0.0437; p = 0.015). The mean flicker response of arteries (ADil) in all groups showed negative correlations to the corresponding metabolic parameter: arterio-venous oxygen extraction fraction (r = −0.101; p = 0.041).
Conclusions: Our study confirms that the flicker light response, despite slight variations in its duration and location, allows for reliable measurements, proving the Retinal Vessel Analyzer to be a valuable diagnostic tool. Furthermore, we were able to highlight the relationship between the dynamic and metabolic components of retinal supply, which enables early diagnosis concerning the development of diseases within this spectrum.
This study evaluated Lolium perenne press juice as a sustainable substrate for Single-Cell Protein (SCP) production using Kluyveromyces marxianus. Key fermentation parameters were systematically optimized, including microbial reduction, dilution ratios, temperature, and nutrient supplementation. Pasteurization at 75 °C preserved essential nutrients better than autoclaving, resulting in a 27.8% increase in biomass yield. A 1:2 dilution of press juice enhanced fermentation efficiency, achieving 20.2% higher biomass despite a lower initial sugar content. Cultivation at 30 °C enabled sustained substrate utilization and outperformed 40 °C fermentation, increasing final biomass by 43.4%. Nutrient supplementation with yeast extract, peptone, and glucose led to the highest biomass yield, with a 71% increase compared to unsupplemented juice. Press juice from the tetraploid variety, Explosion, consistently outperformed the diploid Honroso, especially when harvested early, reaching up to 16.62 g·L−1 biomass. Early harvests promoted faster growth, while late harvests exhibited higher biomass yield coefficients due to improved sugar-to-biomass conversion. Compared to a conventional YM medium, fermentation with L. perenne press juice achieved up to a threefold increase in biomass yield. These findings highlight the potential of grass-based substrates for efficient SCP production and demonstrate how agricultural parameters like variety and harvest timing influence both quantity and quality. The approach supports circular bioeconomy strategies by valorising underutilized biomass through microbial fermentation.
The aim of this work is to study the metabolism of Actinobacillus succinogenes in greater detail with the aim of optimizing succinate production and creating a metabolic model. The inhibitory properties of various substances were first investigated. It was found that the nature and availability of the gas can have a strong influence on metabolism. By studying the effects of different gas sources, it was found that when A. succinogenes lacks a CO2 source, the metabolism completely switches to the C3 pathway. This also completely changes the path within the pathway. In the presence of CO2, significantly more formate (2.44 ± 0.04 g L−1) and significantly less acetate (1.63 ± 0.03 g L−1) was produced. In contrast, in the absence of CO2, the formate concentration was 1.94 ± 0.12 g L−1, and the acetate concentration was 2.73 ± 0.15 g L−1. In addition, larger amounts of ethanol (1.34 ± 0.28 g L−1) were produced in the absence of CO2, whereas hardly any ethanol was produced otherwise. All these results show that, in the absence of a CO2 source, the organism has to regenerate much more NADH to NAD+ via the C3 pathway. In the subsequent investigation of the CO2 source, an increase in product concentration from 1.55 ± 0.13 g L−1 to 6.11 ± 0.09 g L−1 was achieved by combining gaseous CO2 with NaHCO3. It was shown that a microaerobic environment is not sufficient to influence the metabolism of the organism towards lactate formation. Using the model, it was possible to verify the main metabolic pathways observed during experimental bioreactor runs on a 2-L scale. By conducting further modification, it is now possible to use the model to predict the effects of an external electron supply on the redox metabolism.
A user-friendly, portable, low-cost readout system for the on-site or point-of-care characterization of chemo- and biosensors based on an electrolyte–insulator–semiconductor capacitor (EISCAP) has been developed using a thumb-drive-sized commercial impedance analyzer. The system is controlled by a custom Python script and allows to characterize EISCAP sensors with different methods (impedance spectra, capacitance-voltage, and constant-capacitance modes), which are selected in a user interface. The performance of the portable readout system was evaluated by pH measurements and the detection of the antibiotic penicillin, hereby using EISCAPs consisting of Al/p-Si/SiO₂/Ta₂O₅ structures and compared to the results obtained with a stationary commercial impedance analyzer. Both the portable and the commercial systems provide very similar results with almost perfectly overlapping recorded EISCAP signals. The new portable system can accelerate the transition of EISCAP sensors from research laboratories to commercial end-user devices.
The SAMLER-KI (Semi-autonomous Micro Rover for Lunar Exploration using Artificial Intelligence) project aims to open up further potential for future lunar micro rover missions. The focus is on the conceptual design of a micro rover with a higher level of autonomy and the ability to survive the lunar night. Achieving this capability requires a sophisticated thermal design to endure the harsh lunar environment and maintain acceptable temperatures not only during the extreme cold of the lunar night but also while addressing the power demands of autonomous exploration activities during daytime operations. Simultaneously, the structural design must withstand the vibration loads experienced during rocket launch. The design process is challenged by the conflicting requirements between the structural and thermal subsystems, further compounded by the mission’s mass requirement of 20 kg. An initial rover design has been developed in alignment with these requirements and the overall mission scenario. This paper presents a structural and thermal assessment of the preliminary rover design concept under mission-relevant load conditions. The analyses identify critical design weaknesses, including major parasitic thermal pathways and structurally vulnerable components. Although the current design does not yet meet the imposed requirements, the findings provide essential insights into critical areas that show potential for improvement. These results are expected to guide future iterations towards achieving a feasible and robust thermal and structural design.
The increasing demand for bio-based chemicals and sustainable materials has placed biomass-derived lactic acid in the spotlight as a key building block for biodegradable polylactic acid (PLA). Perennial ryegrass (Lolium perenne) is a promising feedstock due to its high dry matter (DM) yield, adaptability, and widespread agricultural use. This study investigates an integrated lactic acid–silage cascade process, focusing on how pH regulation, harvest timing, and biomass characteristics influence lactic acid production while maintaining agronomic efficiency. The results highlighted the crucial role of pH management and silage duration in optimizing lactic acid production. A silage period of 21 days was found to be optimal, as peak lactic acid yields were consistently observed at this stage. Maintaining a pH range of 4.5 to 6 proved essential for stabilizing fermentation, with citrate buffering at pH 6 leading to the highest lactic acid yields and minimizing undesirable by-products. Harvest timing also significantly affected lactic acid yield per hectare. While later harvesting increased total DM yield, it led to a decline in lactic acid concentration per kg DM. Tetraploid ryegrass (Explosion) maintained stable lactic acid yields due to higher biomass accumulation, whereas diploid varieties (Honroso) experienced a net reduction. From an agronomic perspective, optimizing harvest timing and variety selection is key to balancing biomass yield and fermentation efficiency. While tetraploid varieties offer greater flexibility, diploid varieties require precise harvest timing to avoid losses. These findings contribute to sustainable forage management, improving lactic acid production, silage efficiency, and agricultural resource use.
The paper at hand evaluates the necessity of depicting topographic features like boulders on the lunar environment in thermal analyses for a size of up to 6.5 m in diameter. The question regarding the thermal influence becomes relevant when analysing a technical system within the lunar environment. This influence on the thermal behaviour of a test object is investigated in sensitivity studies. It is shown that the local surroundings can significantly alter a system’s net heat flux and can lead to overheating or critically cooling down instead of theoretically surviving when not considering local topographic features. Especially for small and lightweight systems ≤20 kg, like micro rovers, the effect of the surrounding on the system’s temperature becomes critical due to the low thermal capacity. Thus, it is a substantial aspect to be accounted for during the design phase as well as in mission operation.
