Deep Green
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/12328
Browse
9 results
Search Results
Item Open Access Li‐Ion storage and diffusivity in sulfurized polybutadiene containing covalently bound sulfur as a polysulfide shuttle‐free cathode material for Li-S batteries(2024) Muduli, Sadananda; Boecker, Marcel; Prädel, Leon; Neumann, Christof; Du, Qian; Buchmeiser, Michael R.In this work, a new polymer has been explored as a cathode host for lithium‐sulfur batteries (LSBs). Sulfurized polybutadiene materials were synthesized by a single‐step, scalable, and easily tailored heat treatment method. The optimized synthesis process allows for high sulfur loadings of up to 50 wt %. Thermogravimetric analysis‐mass spectrometry (TGA‐MS) and X‐ray photoelectron spectroscopy (XPS) studies confirm that the sulfur is covalently bound to the polymeric backbone, which overcomes the otherwise common capacity‐fading polysulfide shuttle effect of lithium‐sulfur (LSBs) batteries. The absence of free elemental sulfur in the synthesized active materials allows for a stable capacity of up to 1200 mAh g -1 at a rate of C/20. The porous polymer networks reduce the pulverization of the cathode during cycling, resulting in long‐term cycling stability of 1500 continuous galvanostatic charge/discharge (GCD) cycles. Capacity contribution studies depict that at a scan rate of 1 mV s -1 , the sulfurized polybutadiene cathode‐based cells have 65 % capacitive and 35 % diffusive contribution of the total charge stored. A comprehensive study on Li‐ion storage with capacity contribution and diffusion studies of polysulfide shuttle‐free sulfurized polybutadiene cathode material for LSBs is presented.Item Open Access Pressure-temperature-time evolution of a polymetamorphic paragneiss with pseudomorphs after jadeite from the HP-UHP gneiss‐eclogite unit of the Variscan Erzgebirge crystalline complex, Germany(2024) Massonne, Hans‐JoachimA quartz‐rich paragneiss from the Variscan Erzgebirge Crystalline Complex (ECC) was studied in detail because of abundant millimetre‐sized and clearly oriented pseudomorphs after a sodic mineral interpreted to have been jadeite. This mineral, or pseudomorphs after it, is rarely found in extensive high‐pressure (HP)-ultrahigh‐pressure (UHP) terranes worldwide despite reported pressure-temperature (P-T) conditions suitable for the formation of jadeite in common paragneisses and orthogneisses. In the studied rock, which contains abundant large and oriented potassic white mica flakes and minor millimetre‐sized garnet grains, the pseudomorphs consist of clusters of small albite grains with thin phengitic muscovite flakes in between. X‐ray maps for Ca and Mg in garnet demonstrate that an early generation of this mineral (Gt1) was corroded and subsequently overgrown by a Ca‐richer generation (Gt2). White mica is phengite with maximum Si contents of 3.42 atoms per formula unit. P-T conditions of 0.85 GPa and 650°C and 1.7 GPa and 660°C were derived for the formation of Gt1 and Gt2 rim + Si‐rich phengite, respectively, using pseudosection modelling. The latter conditions representing the pressure peak experienced by the paragneiss are compatible with the original presence of jadeite and possibly paragonite as well. This metamorphic peak occurred at 338.4 ± 2.3 (2σ) Ma based on in situ dating of monazite grains with the electron microprobe. A single monazite age of 386.4 ± 10.5 (2σ) Ma is related to the formation of Gt1. Thus, a Late Devonian metamorphism is suggested here for the first time to have occurred in ECC gneisses before the major HP event in the Early Carboniferous. Furthermore, the study demonstrates that the eclogite‐facies gneisses of the Gneiss‐Eclogite Unit of the ECC experienced peak pressures of not more than 2 GPa in contrast to recent proposals of an extensive UHP area in this unit. In addition, it is suggested that the localized occurrence of UHP rocks surrounded by other lithologies otherwise lacking evidence for UHP conditions should be interpreted with caution with respect to their regional extent and significance.Item Open Access Anforderungen für Take-Back Systeme im Zeitalter der digitalen Nachhaltigkeit(2024) Petrik, Dimitri; Truckses, Dana; Strobel, GeroDer Übergang zur nachhaltigen Wertschöpfung ist ein wichtiges gesamtgesellschaftliches Ziel. Insbesondere in ressourcenintensiven Domänen gehen die Organisationen und ganze Wertschöpfungsketten zunehmend dazu über, ihre Prozesse an den Prinzipien der Kreislaufwirtschaft (Circular Economy) auszurichten. Zur Realisierung der Kreislaufwirtschaft sind Produktrücknahmesysteme (Take-Back Systems) von grundlegender Bedeutung. Sie konzentrieren sich auf die Rückgewinnung von Ressourcen durch die Rücknahme von Produkten. Vor diesem Hintergrund zeigt dieser Artikel die Rolle von Informationssystemen (IS) bei der Realisierung von Take-Back Systemen auf. Dazu sollen spezifische Aspekte identifiziert werden, wie IS in Bezug auf die Effizienz, Transparenz und Effektivität von Take-Back Systemen von Produkten zur Förderung der Kreislaufwirtschaft beitragen können. Die Analyse dieser Informationen dient der Ableitung von Anforderungen für IS zur Unterstützung von Take-Back Systemen. Zur Ableitung der Anforderungen wurde eine systematische Literaturanalyse durchgeführt, um einen detaillierten Überblick über die Aspekte von Take-Back Systemen zu erhalten und in IS-Funktionen zu überführen. Diese Analyse resultiert in einem Anforderungskatalog für IS zur Unterstützung von Take-Back Systemen. Der Anforderungskatalog wurde von vier Experten evaluiert und erweitert. Abschließend werden die gesammelten Erkenntnisse aus der Literaturrecherche und den Expertengesprächen genutzt, um die Implikationen für die Enterprise-Softwarelandschaften zu diskutieren. Insgesamt verdeutlichen die Ergebnisse die fundamentale Rolle der digitalen Nachhaltigkeit und zeigen, wie digitale Technologien und IS bei der Unterstützung von Take-Back Systemen zur Ressourcenschonung beitragen können. Entsprechend helfen die Ergebnisse dieses Artikels bei der Ausrichtung von Unternehmenssoftware für den Übergang von einer linearen Wirtschaft zu einer Kreislaufwirtschaft.Item Open Access Assessing advanced propulsion systems using the impact monitor framework(2025) Gupta, Utkarsh; Riaz, Atif; Brenner, Felix; Lefebvre, Thierry; Ratei, Patrick; Alder, Marko; Prakasha, Prajwal Shiva; Weber, Lukas; Pons-Prats, Jordi; Markatos, DionysiosPresented in this paper is the Impact Monitor framework and interactive Dashboard Application (DA) validated through a use case, focusing on investigating the viability and competitiveness of future propulsion architectures for next-generation aircraft concepts. This paper presents a novel collaborative framework for integrated aircraft-level assessments, focusing on secure, remote workflows that protect intellectual property (IP) while enabling comprehensive and automated analyses. The research addresses a key gap in the aerospace domain: the seamless matching and sizing of aircraft engines within an automated workflow that integrates multiple tools and facilitates real-time data exchanges. Specifically, thrust requirements are iteratively shared between aircraft and engine modeling environments for synchronized sizing. Subsequently, the fully defined aircraft data are transferred to other tools for trajectory analysis and emissions and other assessments. The Impact Monitor framework and Dashboard Application demonstrate improved efficiency and data security, promoting effective collaboration across institutions and industry partners.Item Open Access Exploring Phaeodactylum tricornutum for nutraceuticals : cultivation techniques and neurotoxin risk asssessment(2025) Ebbing, Tobias; Kopp, Lena; Frick, Konstantin; Simon, Tabea; Würtz, Berit; Pfannstiel, Jens; Schmid-Staiger, Ulrike; Bischoff, Stephan C.; Tovar, Günter E. M.This study investigates the potential of the diatom Phaeodactylum tricornutum (PT) as a sustainable and nutritionally valuable food source, focusing on its ability to produce bioactive compounds such as eicosapentaenoic acid, fucoxanthin, chrysolaminarin (CRY) and proteins. PT was cultivated in a flat-plate airlift photobioreactor (FPA-PBR) illuminated with LEDs from two sides. The study aimed to monitor and minimize β-methylamino-L-alanine (BMAA) levels to address safety concerns. The data showed that the selected FPA-PBR setup was superior in biomass and EPA productivity, and CRY production was reduced. No BMAA was detected in any biomass sample during cultivation. By adjusting the cultivation conditions, PT biomass with different compositional profiles could be produced, enabling various applications in the food and health industries. Biomass from nutrient-repleted conditions is rich in EPA and Fx, with nutritional and health benefits. Biomass from nutrient-depleted conditions accumulated CRY, which can be used as dietary fiber. These results highlight the potential of PT as a versatile ingredient for human consumption and the effectiveness of FPA-PBRs with artificial lighting in producing high-quality biomass. This study also provides the basis for future research to optimize photobioreactor conditions to increase production efficiency and to tailor the biomass profiles of PT for targeted health-promoting applications.Item Open Access Adapting e-Genius for next-level efficient electric aerotow with high-power propulsion and automatic flight control system(2025) Zistler, Stefan; Shi, Dalong; Fichter, Walter; Strohmayer, AndreasAiming to reduce energy demand and carbon footprint, minimize noise impact, and enhance flight safety and efficiency during aerotow operations, this study integrates an electric propulsion system and an automatic flight control system (AFCS) into the electric research aircraft e-Genius. An advanced propulsion system is developed using high-performance batteries and available electric drive components, while the AFCS is designed following a systematic process of developing flight control algorithms. Flight tests are then conducted to evaluate the performance of individual components and the overall system. The test results demonstrate that the upgraded propulsion system provides sufficient power to launch sailplanes, even with the maximum takeoff mass, while significantly reducing energy demand when compared to contemporary fossil fueled towplanes. Additionally, the AFCS proves to be stable and robust, successfully following specified commanded states, executing path tracking, and performing aerotow operations.Item Open Access Crystal structure of rac-(6R,1'R)-6-(1',2'-diacetoxyethyl)-2-phenyl-5,6-dihydro-4H-1,3-oxazine, (C6H5)C4H5NO[C2H3(OCOCH3)2](2014) Peters, K.; Peters, E.-M.; Kugler, Rolf; Jäger, VolkerC16H19NO5, triclinic, P‾1 (No. 2), a = 9.211(1) Å, b = 9.259(2) Å, c = 9.796(2) Å, α = 84.36(1)°, β = 85.26(1)°, γ = 69.21(1)°, V = 776.2 Å3, Ζ = 2, Rgt(F) = 0.069, Rw(F) = 0.069, Τ = 293 Κ.Item Open Access The role of spacer length in macrocyclization reactions under confinement(2024) Nandeshwar, Muneshwar; Weisser, Kilian; Ziegler, Felix; Frey, Wolfgang; Buchmeiser, Michael R.We studied the influence of the distance of olefin metathesis catalysts from the inner surface of a mesoporous support on macrocyclization and Z‐selectivity under confinement. For these purposes, the cationic molybdenum imido alkylidene N‐heterocyclic carbene (NHC) catalysts [Mo(N‐(2‐tBu‐C6H4)(1‐mesityl‐3‐(3‐trimethoxysilylprop‐1‐yl)‐imidazol‐2‐ylidene)(CHCMe2Ph)(MeCN)Br+ B(ArF)4-] Mo2, [Mo(N‐(2‐tBu‐C6H4)(1‐mesityl‐3‐(3‐trimethoxysilylprop‐1‐yl)‐imidazol‐2‐ylidene)(CHCMe2Ph)(MeCN)OTf+ B(ArF)4-] Mo3, [Mo(N‐(2,6‐Me2‐C6H3)(1‐mesityl‐3‐(3‐trimethoxysilylprop‐1‐yl)‐imidazol‐2‐ylidene)(CHCMe2Ph)(MeCN)Br+ B(ArF)4-] Mo5, and [Mo(N‐(2,6‐iPr2‐C6H3)(1‐mesityl‐3‐(3‐trimethoxysilylprop‐1‐yl)‐imidazol‐2‐ylidene)(CHCMe2Ph)(MeCN)+Br B(ArF)4-] Mo7 (B(ArF)4 = tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate), all containing a trimethoxysilylpropyl tether, were selectively immobilized inside the mesopores of SBA‐15. Under confinement, both macro(mono)cyclization (MMC) and Z‐selectivity were higher than in solution but lower than with catalysts directly bound to the surface of the mesoporous supports. These findings are in agreement with existing theoretical models on substrate and product distribution in mesopores, which suggest that the highest substrate concentration is found at the pore wall and that it increases with decreasing pore diameter.Item Open Access Controlling grain boundary segregation to tune the conductivity of ceramic proton conductors(2024) Kindelmann, Moritz; Povstugar, Ivan; Kuffer, Severin; Jennings, Dylan; Ebert, Julian N.; Weber, Moritz Lukas; Zahler, Pascal; Escolastico, Sonia; Almar, Laura; Serra, Jose M.; Kaghazchi, Payam; Bram, Martin; Rheinheimer, Wolfgang; Mayer, Joachim; Guillon, OlivierAcceptor‐doped barium zirconates are of major interest as proton‐conducting ceramics for electrochemical applications at intermediate operating temperatures. However, the proton transport through polycrystalline microstructures is hindered by the presence of a positive space charge potential at grain boundaries. During high‐temperature sintering, the positive charge acts as a driving force for acceptor dopant segregation to the grain boundary. Acceptor segregation to grain boundaries has been observed in sintered ceramics, but the fundamental relationship between the segregation kinetics and the protonic conductivity is poorly understood. Here, a comprehensive study of the influence of acceptor dopant segregation on the electrochemical properties of grain boundaries in barium zirconate ceramics is presented. An out‐of‐equilibrium model material that displays no detectable Y segregation at its grain boundaries is explicitly designed. This model material serves as a starting point to measure the kinetics of segregation and the induced changes in grain boundary conductivity upon varying thermal histories. Furthermore, the electrochemical results from impedance spectroscopy to atomic resolution transmission electron microscopy, atom probe tomography, and DFT simulations are correlated. It is discovered that acceptor dopant segregation drastically increases the proton conductivity in both the model system and several other application‐relevant compositions.