Deep Green
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/12328
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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 Multi-objective optimization of a folding photovoltaic-integrated light shelf using non-dominated sorting genetic algorithm III for enhanced daylighting and energy savings in office buildings(2025) Cheraghzad, Tanin; Zamani, Zahra; Hakimazari, Mohammad; Norouzi, Masoud; Karimi, AlirezaThis study developed a novel folding light shelf system that integrates reflectors, photovoltaic (PV) modules, and adaptive louvers that adjust based on solar altitude, aiming to improve daylight distribution, minimize glare, and reduce energy consumption in office buildings. The research employed an advanced optimization approach, utilizing Non-dominated Sorting Genetic Algorithm III (NSGA-III) and Latin Hypercube Sampling, a highly effective method suitable for managing complex multi-objective scenarios involving numerous variables, to efficiently identify high-performance configurations with increased precision. Key design variables across all three components of the system included angle, width, distance, and the number of folds in the light shelf, along with the number of louvers. The proposed method successfully integrates PV technology into light shelves without compromising their functionality, enabling both daylight control and energy generation. The optimization results demonstrate that the system achieved up to a 15% improvement in useful daylight illuminance (UDI) and a 16% reduction in cooling energy consumption. Furthermore, the PV modules generated 509.5 kWh/year, ensuring improved efficiency and sustainability in building performance.Item Open Access Biodegradable, antibacterial TCP implant coatings with magnesium phosphate‐based supraparticles(2025) Lanzino, Maria Carolina; Höppel, Anika; Le, Long‐Quan R. V.; Morelli, Stefania; Killinger, Andreas; Rheinheimer, Wolfgang; Mayr, Hermann O.; Dembski, Sofia; Al‐Ahmad, Ali; Mayr, Moritz F.; Gbureck, Uwe; Seidenstuecker, MichaelThis work highlights the potential of porous, bioactive coatings to advance implant technology and address critical clinical challenges. A key issue in implant coatings is to achieve the balance between infection prevention and successful osseointegration. Although titanium implants are widely used due to their mechanical strength and biocompatibility, their bioinert nature limits integration with bone tissue. To address these issues, porous calcium phosphate (CaP) coatings have been developed to enhance cell attachment and bone growth. However, CaP, especially in the widely used form of hydroxyapatite (HAp), has a low resorption rate, which often leads to prolonged coating stability and impairs natural bone remodeling. To overcome this limitation, magnesium phosphate (MgP), an underexplored but promising biomaterial with high biocompatibility and osteogenic potential, can be introduced. Another innovative strategy is the doping of biomaterials with antibacterial ions, among which copper (Cu) has attracted particular attention. The incorporation of Cu into the coating matrix can significantly reduce the risk of post‐operative infection while promoting angiogenesis, a key factor for rapid and stable implant integration. This study presents bone implant coatings composed of tricalcium phosphate (TCP) and Cu‐doped MgP clustered nanoparticles (supraparticles) fabricated via high‐velocity suspension flame spraying (HVSFS). This particle system addresses current challenges in bone tissue regeneration by synergistically combining the high biodegradability of MgP, the bone‐mimicking properties of CaP, and the antibacterial capabilities of Cu. In addition, the HVSFS process enables the creation of thin layers with porous microstructures. Biocompatibility of the prepared coatings was assessed using MG63 osteosarcoma cells, while the antibacterial efficacy was tested against Staphylococcus aureus and Escherichia coli . The incorporation of Cu‐doped MgP supraparticles (MgPCu and MgPCu HT) into TCP coatings resulted in high Cu release and pronounced antibacterial efficacy compared to the TCP reference, while the addition of Cu‐doped FT supraparticles (FTCu) led to high cell proliferation.Item Open Access Co‐doping approach for enhanced electron extraction to TiO2 for stable inorganic perovskite solar cells(2025) Gries, Thomas W.; Regaldo, Davide; Köbler, Hans; Putri Hartono, Noor Titan; Harvey, Steven P.; Simmonds, Maxim; Frasca, Chiara; Härtel, Marlene; Sannino, Gennaro V.; Félix, Roberto; Hüsam, Elif; Saleh, Ahmed; Wilks, Regan G.; Zu, Fengshuo; Gutierrez‐Partida, Emilio; Iqbal, Zafar; Loghman Nia, Zahra; Yang, Fengjiu; Delli Veneri, Paola; Zhu, Kai; Stolterfoht, Martin; Bär, Marcus; Weber, Stefan A.; Schulz, Philip; Puel, Jean‐Baptiste; Kleider, Jean‐Paul; Unger, Eva; Wang, Qiong; Musiienko, Artem; Abate, AntonioInorganic perovskite CsPbI3 solar cells hold great potential for improving the operational stability of perovskite photovoltaics. However, electron extraction is limited by the low conductivity of TiO2, representing a bottleneck for achieving stable performance. In this study, a co‐doping strategy for TiO2 using Nb(V) and Sn(IV), which reduces the material's work function by 80 meV compared to Nb(V) mono‐doped TiO2, is introduced. To gain fundamental understanding of the processes at the interfaces between the perovskite and charge‐selective layer, transient surface photovoltage measurements are applied, revealing the beneficial effect of the energetic and structural modification on electron extraction across the CsPbI3/TiO2 interface. Using 2D drift‐diffusion simulations, it is found that co‐doping reduces the interface hole recombination velocity by two orders of magnitude, increasing the concentration of extracted electrons by 20%. When integrated into n-i-p solar cells, co‐doped TiO2 enhances the projected TS80 lifetimes under continuous AM1.5G illumination by a factor of 25 compared to mono‐doped TiO2. This study provides fundamental insights into interfacial charge extraction and its correlation with operational stability of perovskite solar cells, offering potential applications for other charge‐selective contacts.Item Open Access Polycondensation‐derived high‐molecular weight lignin as nonblended precursor for carbon fibers(2024) Clauss, Manuel M.; Frank, Erik; Bauch, Volker; Kuske, Lisa; Buchmeiser, Michael R.A new concept for the controlled chain‐extension of lignin has been developed. A mixture of trioxane as formaldehyde source, resorcinol as chain extender, and lignin allows to prepare high molecular weight precursor fibers by melt‐spinning, which can be spun on a semitechnical scale. Chain extension with resorcinol bridged by methylene groups is achieved during the stabilization process of the precursor fiber. After carbonization, carbon fibers (CFs) with an average diameter of 18 µm show an average tensile strength of 0.78 GPa and a Young's modulus of 106 GPa. A maximum tensile strength of 2.44 GPa and a Young's modulus of 294 GPa are reached with fibers 9.7 µm in diameter.Item Open Access Direct air capture via counter‐current NaOH absorption system : evolution of pH for subsequent plasma‐enhanced CO₂ utilization(2025) Seithümmer, Valentin Benedikt; Dubiel, Christoph; Kaufmann, Samuel Jaro; Chinnaraj, Haripriya; Rößner, Paul; Birke, Kai PeterDirect air capture (DAC) technologies offer a promising approach to mitigate anthropogenic climate change by enabling net negative emissions. CO2 absorption using NaOH represents an efficient solution within the proposed BlueFire carbon cycle, which integrates DAC with plasma technology for syngas production. Optimizing a DAC plant control relies on understanding the pH profile as a key parameter. A bubble column absorption model with pure CO2 was experimentally adapted for a counter‐current flow setup with ambient air, reproducing a staged pH decrease. An optimal absorption endpoint was determined by identifying the maximum slope of the pH decline, indicating high reaction progress. X‐ray diffraction analysis of the absorption products validated the theoretical model of carbonate formation.Item Open Access Physical interpretation of interwell partitioning tracer tests for estimation of remaining oil saturation in layered carbonate reservoirs(2025) Fontalvo, Samuel D.; Yutkin, Maxim P.; Hassanizadeh, S. Majid; Radke, Clayton J.; Patzek, Tadeusz W.Interwell partitioning tracer tests (IPTTs) are conducted in mature oil fields to estimate remaining oil in place, which is crucial for subsequent economic analyses and decisions regarding further field development. An IPTT involves the simultaneous injection of two types of tracers: conservative and partitioning, that probe the aqueous and oil phases, respectively. Although this test requires time, it probes the entire fluid flow path, not just the near-wellbore area, as is the case with other methods such as single-well tests. Accurate interpretation of interwell tracer test data is of critical importance for the oil and gas industry. Published IPTT case studies lack physical justification for the choice of tracer flow models. In this study, we provide such justifications along with guidelines for selecting appropriate tracer flow models. First, we review existing models for the transport of partitioning and conservative tracers and demonstrate their applicability range based on mass conservation analysis. Based on this analysis, we propose a refined model of partitioning tracer flow with Robin boundary conditions that accounts for non-equilibrium partitioning. Such analysis is missing in the literature. Next, we illustrate errors in estimating remaining oil if an inappropriate model is used for data interpretation. Notably, the choice of an incorrect model can lead to either underestimation or overestimation of the remaining oil, with the latter being of greater financial concern. Finally, we apply the non-equilibrium partitioning model to a published IPTT dataset from a layered carbonate reservoir and compare our remaining oil estimates with results of the original study. To the best of our knowledge, analysis of such cases with non-equilibrium partitioning has not been documented in the literature.Item Open Access What makes a branched aromatic compound a crystallization chaperone? Insights from a comparison of three organic scaffolds(2025) Hartenfels, Jan; Berking, Tim; Rebelo, Ruben Pereira; Tsimopoulou, Katerina; Schiele, Stefanie; Stark, Leon; Frey, Wolfgang; Richert, ClemensSome tetraaryladamantane (TAA) octa‐ and tetraethers have the ability to crystallize into well‐ordered lattices without full desolvation. In many cases, the solvates then yield high‐resolution X‐ray crystal structures of the encapsulated liquids. To shed light on this unusual effect of TAAs as crystallization chaperones, we have synthesized a series of spirobiflourene and porphyrin derivatives with four phenyl arms also found in TAA chaperones. Despite the structural similarity, neither of the non‐TAA compounds showed promising crystallization properties. Six new X‐ray crystal structures were obtained, but neither gave a high‐resolution structure of an encapsulated guest. Quantum chemical computations suggest that conformational changes have low activation barriers for the TAAs, which may help to adapt to the structures of guest molecules in tightly packed arrangements. These findings on supramolecular chemistry in the crystalline state may help to design new chaperones with improved properties.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.