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Auf dem Weg zur oberflächenverstärkten homogenen Katalyse: Maßgeschneiderte Anreicherung von Metallkomplexen an der Oberfläche von ionischen Flüssigkeiten
No full textSustainable co-production of H2 and lactic acid from lignocellulose photoreforming using Pt-C3N4 single-atom catalyst
No full textAdvancing Na-Based Batteries through Structural Deep Dives: Insights from P2-Cathodes and Anode-Free Functional Materials
No full textSeed Fund OpTooGlu - Optogenetic Toolbox for Two-color Light-controlled Gene Expression in the Acetic Acid Bacterium Gluconobacter oxydans
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Bridging the Nanoscale Gap: Multimodal Electron Microscopyfor Advancing Electrolyzer Technologies
No full textThe transition to a sustainable energy future is inseparably linked to the development of efficient and reliable hydrogen production technologies. Electrolysis, encompassing both low-temperature (PEM/AEM) and high-temperature (SOFC/SOEC) approaches, holds immense promise. However, a significant hurdle remains: a comprehensive understanding of the complex electrochemical processes at the nanoscale and how that translates to macro-scale performance and durability. This presentation shows how advanced electron microscopy can address this challenge.Overall our research aims to correlate fundamental nanoscale mechanisms with device performance in both low- and high-temperature electrolysis by developing and implementing a comprehensive multimodal electron microscopy strategy. We emphasize visualizing nanoscale dynamics using in-situ transmission electron microscopy (TEM) and correlating these observations with the microstructural changes in lab or large-scale cells during long-term operation via a multimodal approach. Specifically, the low- and high-temperature electrolysis present distinct microscopy challenges. Beam-sensitive AEM and PEM electrolytes and catalysts necessitate low-dose TEM and cryo-sample preparation. Maintaining critical hydration states during imaging is crucial for accurate degradation mechanism analysis. Furthermore, the limitations of single-chamber MEMS-based in-situ TEM cells for gas/liquid phase reactions require careful consideration of electrochemical processes to maximize the information gained. Finally, the limited field of view and thin sample requirements of TEM necessitate careful consideration of broader relevance.Thus, we combine laser scanning microscopy (LSM) for large-scale context, (cryo) plasma FIB for precise TEM sample preparation or obtaining high-resolution 3D information to construct a comprehensive picture of the material's structure and behavior. Then, employ well though in-situ TEM investigation in (environmental) TEM to obtain necessary nanoscale process information. This presentation will showcase unique degradation processes observed in PEM electrolysis and the nano-exsolution process and its long-term stability in high-temperature electrolysis. These nanoscale insights are crucial for the rational design and optimization of next-generation electrolyzers, accelerating the transition to a hydrogen-based economy
Can ePDF Detect Water in Silicon Nitride Liquid Cells?
No full textRecent developments in in situ and environmental TEM have significantly advanced our ability to study dynamic processes at the nanoscale. Innovations in liquid and gas cell TEM have enabled real-time imaging of chemical reactions, material transformations, and biological processes under realistic conditions. Many of these processes are inherently heterogeneous and involve precipitation or crystallization. The most straightforward method for detecting early crystallization states in a liquid phase is the analysis of the electron Pair Distribution Function (ePDF).Amorphous silicon nitride is one of the most widely used materials for in situ TEM liquid cells. As a result, the contribution of the membrane signal is inevitably present in the diffraction data of the sample. It is therefore crucial to analyze and understand the contributions of both the Si3N4 membrane and water as a solvent to accurately assign evolving structural features and distinguish them from the signal of the reaction species.Detecting water in the presence of Si3N4 is not a trivial task, as most interatomic distances in their respective Pair Distribution Functions overlap. Consequently, rather than tracing the appearance of additional peaks, we must analyse the distribution of intensities, which are generally less reliable in ePDF due to multiple scattering.Here, we present our results on the ePDF analysis of water-filled Si3N4 chips, demonstrating the information that can be extracted from ePDF data and discussing the limitations of the procedure
Genotypic variation in root and shoot traits of wheat suggesting an indirect effect of breeding on nitrogen efficiency
No full textWheat (Triticum aestivum) production in Europe relies heavily on nitrogen fertilizer inputs, negatively affecting soil, air, and water quality. An approach to reduce agriculturally caused nitrogen emissions is breeding of nitrogen-efficient crop cultivars. To investigate whether breeding approaches in recent decades have already indirectly targeted nitrogen efficiency in wheat, a collection of winter wheat cultivars released over a period of 50 years was examined under control and nitrogen-deficient conditions. Selected cultivars were grown in soil-filled rhizotrons for 15 days under greenhouse conditions to enable phenotyping of root and shoot growth at the seedling stage. During the experimental period, plants were phenotyped every two to three days for root and shoot traits. Additionally, physiological measurements were taken once before the end of the experimental period to quantify chlorophyll content, leaf-level spectral reflectance and the photosynthetic trait quantum yield of photosystem II. After the plants were harvested, root and shoot biomass were assessed destructively. Generally, all cultivars showed a reduction of shoot growth in favor of root growth in response to nitrogen deficiency. Genotypic variation was observed for physiological parameters under both control and nitrogen deficiency. Multivariate analysis, considering morphological and physiological shoot and root traits, revealed clustering of the cultivars roughly according to their year of release. In summary, our phenotypic data hint towards improved nitrogen efficiency in younger cultivars, which implies an indirect selection of genotypes with high nitrogen efficiency in wheat breeding progress over the last few decades
Influence of Contact Map Topology on RNA Structure Prediction
No full textThe available sequence data of RNA molecules have greatly increased in the past years. Unfortunately, while computational power is still under exponential growth, the computer prediction quality from sequence to final structure is still inferior to labour-intensive experimental work. Although a reliable end-to-end procedure has already been developed for proteins since Alphafold2, while its successor AlphaFold3 can also predict RNA, its confidence, in particular for novel sequences and folds, still appears limited. Another strategy entails two steps: (i) predicting potential contacts in the form of a contact map from evolutionary data; and (ii) simulating the molecule with a physical force field while using the contact map as restraint. However, the quality of the structure prediction crucially depends on the quality of the contact map. Until now, only the proportion of true positive contacts was considered as a quality characteristic. We propose to also include the distribution of these contacts, and have done so in our recent studies. We observed that the clustering of contacts, as is common for many artificial intelligence algorithms, has a negative impact on prediction quality. In contrast, a more distributed topology is beneficial. We have applied these findings from computer experiments to current algorithms and introduced a measure of distribution, the Gaussian score