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„Wenn du zwei Hasen hinterherläufst, dann fängst du keinen“ – Zum Erleben Innerer Differenzierung als Herausforderung in Vorbereitungsklassen
No full textUm den Lernvoraussetzungen und -bedürfnissen aller Schüler:innen gerecht zu werden, wird sowohl aus bildungspolitischer als auch schulpädagogischer Perspektive ein differenzierendes Arbeiten in Vorbereitungsklassen für neu zugewanderte Schüler:innen gefordert (vgl. BSB 2023; Benz/Aschenbrenner/Jeuk 2017). Der vorliegende Beitrag untersucht anhand von Interviewdaten mit einer Lehrerin einer Vorbereitungsklasse und gerahmt durch ethnographische Erkenntnisse, wie die Herausforderung der Inneren Differenzierung in Vorbereitungsklassen in der Praxis erlebt wird. Basierend auf der Beobachtung, dass die Lehrerin während der Corona-Pandemie auf eine Äußere Differenzierung zurückgriff und dies als Idealzustand skizziert, werden strukturelle Fragen zur Separation und Inklusion neu zugewanderter Schüler:innen aufgeworfen
Influence of TEMPO-oxidation on pulp fiber chemistry, morphology and mechanical paper sheet properties
No full textIn this contribution, we report on the TEMPO-mediated oxidation of pulp fibers used in the general context of papermaking and for the future design of tailor-made paper in advanced applications. We focus in our studies on properties of TEMPO-oxidized pulp fibers to explain the characteristics of the paper made thereof. 13C solid-state NMR analysis reveals that in particular amorphous regions of the fibers are being chemically oxidized, while at the same time the crystalline regions of the fibers are not significantly affected. Investigation of the fiber morphology before and after oxidation shows that the fiber length is not changed, yet the fibers do exhibit an increase in width if in contact with water, which is attributed to an increase in fiber swelling. In addition, fibrillation decreases due to the oxidative removal of loosely bound fines and fibrils, rendering the surface of the resulting oxidized fibers much smoother in comparison to the original fibers. Finally, we observe that both, dry and wet tensile strengths are also higher for paper made of oxidized fibers, most likely due to cross linkable aldehyde groups formed during oxidation (i.e. hemiacetal bond formation in the sheet during thermal drying). Our results of the oxidation of paper fibers thus offer a systematic study helpful for the design of tailor-made paper useful in several applications where a fiber-modification with fiber-immobilized functional motifs is crucial, such as for example in paper-based microfluidic sensors (µPADs) or lab-on a chip-devices
IDOVIR — Infrastructure for Documentation of Virtual Reconstructions: Towards a Documentation Practice for Everyone
No full textSource-based virtual reconstructions have become essential tools for communication and research in urban and architectural studies. While these reconstructions are often showcased through exhibition visualizations, the underlying knowledge is not always apparent or even documented. This raises concerns about their sustainability. Without transparent, publicly accessible documentation of the decision-making processes (known as paradata) that come with and support these digital reconstructions, there is a risk of losing both the knowledge embedded in them and their potential scientific value. To enhance transparency and allow for proper assessment and recognition of these reconstructions, thorough documentation and evaluation of the reconstruction processes are crucial. Although there are various approaches to documenting virtual reconstructions tailored to specific use cases, and while some focus on aspects like visualizing reliability, the overall process of documentation remains cumbersome and costly, making it an exception rather than the norm. Previous tools that claim to properly document virtual reconstructions either cover only part of the metadata and linked sources, are too complicated to use, or are no longer available. Currently, there is no universally accepted, straightforward, and easy-to-use workflow for this purpose. The IDOVIR project addresses this gap by offering a user-friendly, web-based platform designed specifically for documenting digital architectural reconstructions. We strive for achieving such a standardized workflow. To date, the platform has already been adopted by a large number of users, and many projects are publicly accessible
Zum 100. Geburtstag von Gerd Fesel
No full textWer sich am Campus Lichtwiese umschaut, wird schnell auf ein auffälliges Gebäude stoßen, das von außen fast gänzlich in den Farben Rot und Gelb gehalten ist: die Maschinenbauhalle. Ihre Farbgebung ist wohlbegründet. Ihre einzelnen Systeme sind Farben zugeordnet. So ist die Primärstruktur (das Tragwerk) in Blau gehalten, die Sekundärstruktur (konstruktive Teile nicht tragender Wände) ist schwarz; raumbildende, nicht tragende Innenwände sind weiß, die Füllungen der Außenwände sind außen rot und innen sandfarben, die Füllungen der Schächte sind orange, die Kranbahnen chrom-gelb und die Betonkerne neapel-gelb. Den Innenräumen gab der Architekt einen Überschuss an Gelb, um ein möglichst warmes Klima zu erzeugen
Managing High Groundwater Velocities in Aquifer Thermal Energy Storage Systems: A Three-Well Conceptual Model
No full textAquifer Thermal Energy Storage (ATES) is a promising technology for the seasonal storage of heat, thereby bridging the temporal gap between summer surpluses and peak winter demand. However, the efficiency of conventional ATES systems is severely compromised in aquifers with high groundwater flow velocities, as advective heat transport leads to significant storage losses. This study explores a novel three-well concept that implements an active hydraulic barrier, created by an additional extraction well upstream of the ATES doublet. This well effectively disrupts the regional groundwater flow, thereby creating a localized zone of stagnant or significantly reduced flow velocity, to protect the stored heat. A comprehensive parametric study was conducted using numerical simulations in FEFLOW. The experiment systematically varied three key parameters: groundwater flow velocity, the distance of the third well and its pumping rate. The performance of the system was evaluated based on its thermal recovery efficiency and a techno-economic analysis. The findings indicate that the hydraulic barrier effectively enhances heat recovery, surpassing twice the efficiency observed in a conventional two-well configuration (100 m/a). The analysis reveals a critical trade-off between hydraulic containment and thermal interference through hydraulic short-circuiting. The techno-economic assessment indicates that the three-well concept has the potential to generate significant cost and CO₂e savings. These savings greatly exceed the additional capital and operational costs in comparison to a traditional doublet system in the same conditions. In conclusion, the three-well ATES system can be considered a robust technical and economic solution for expanding HT-ATES to sites with high groundwater velocities; however, its success depends on careful, model-based design to optimize these competing effects
A Geothermal-Driven Zero-Emission Poly-Generation Energy System for Power and Green Hydrogen Production: Exergetic Analysis, Impact of Operating Conditions, and Optimization
No full textSince the hydrogen-production process is not yet fully efficient, this paper proposes a poly-generation system that is driven by a geothermal energy source and utilizes a combined Kalina/organic Rankine cycle coupled with an electrolyzer unit to produce, simultaneously, power and green hydrogen in an efficient way. A comprehensive thermodynamic analysis and an exergetic evaluation are carried out to assess the effect of key system parameters (geothermal temperature, high pressure, ammonia–water concentration ratio, and terminal thermal difference) on the performance of concurrent production of power and green hydrogen. Thereby, two configurations are investigated with/without the separation of turbines. The optimal ammonia mass fraction of the basic solution in KC is identified, which leads to an overall optimal system performance in terms of exergy efficiency and green hydrogen production rate. In both configurations, the optimal evaluation is made possible by conducting a genetic algorithm optimization. The simulation results without/with the separation of turbines demonstrate the potential of the suggested cycle combination and emphasize its effectiveness and efficiency. Exemplary, for the case without the separation of turbines, it turns out that the combination of ammonia–water and MD2M provides the best performance with net power of 1470 kW, energy efficiency of 0.1184, and exergy efficiency of 0.1258 while producing a significant green hydrogen amount of 620.17 kg/day. Finally, an economic study allows to determine the total investment and payback time of $3,342,000 and 5.37 years, respectively. The levelized cost of hydrogen (LCOH) for the proposed system is estimated at 3.007 USD/kg H₂, aligning well with values reported in the literature
Sandwich panels with functionally graded strut‐based lattice cores
No full textDue to their high mechanical performance, sandwich panels are widely utilized in many applications. Among the most frequently used cores in sandwich panels are honeycomb structures. Since the invention of additive manufacturing, new core structures like strut‐based lattices which are not possible by conventional manufacturing processes are also being considered as cores for sandwich panels. Depending on the given boundary conditions and load cases, core struts must transfer different loads. Particularly struts near load introduction points and support points are exposed to high local stresses. In the present study, a graded core is used to reduce the effect of local stress concentration near load introduction points and support points. In the graded core higher loaded areas show a higher relative density. In contrast, low loaded areas represent lower relative density, resulting in a reduction of the core weight and a uniform stress distribution. Only the strut diameters are varied. It is demonstrated that systematic optimization allows a well‐tailored core gradation and some valuable weight reduction
Computational Prediction of Single-Domain Immunoglobulin Aggregation Propensities Facilitates Discovery and Humanization of Recombinant Nanobodies
No full textBackground/Objectives: Single-domain immunoglobulins are small protein modules with specific affinities. Among them, the variable domains of heavy chains of heavy-chain-only antibodies (VHH) as the antigen-binding fragment of heavy-chain-only antibodies (also termed nanobodies) have been widely investigated for their applicability, e.g., therapeutics and immunodiagnostics. However, despite their advantageous biochemical and biophysical characteristics, protein aggregation throughout recombinant synthesis is a serious drawback in the development of nanobodies with application perspectives. Therefore, we aimed to develop a computational method to predict the aggregation propensity of VHH antibodies for the selection of promising candidates in early discovery. Methods: We employed a deep learning-based structure prediction for VHHs and derived from it likely biophysical and biochemical properties of the framework region 2 with relevance for aggregation. A total of 106 nanobody variants were produced by recombinant expression and characterized for their aggregation behavior using size exclusion chromatography (SEC). Results: Quantitative characteristics of framework region 2 patches were combined into a function that defines an aggregation score (AS) predicting the aggregation propensities of VHH variants. AS was evaluated for its capability to forecast recombinant VHH aggregation by experimentally studying VHH Fc-fusion proteins for their aggregation. We observed a clear correlation between the calculated aggregation score and the actual aggregation propensities of biochemically characterized VHHs Fc-fusion proteins. Moreover, we implemented an easily accessible pipeline of software modules to design nanobodies with desired solubility properties. Conclusions: AI-based prediction of VHH structures, followed by analysis of framework region 2 properties, can be used to predict the aggregation propensities of VHHs, providing a convenient and efficient tool for selecting stable recombinant nanobodies
Impact of Charge-Transfer Excitons on Unidirectional Exciton Transport in Lateral TMD Heterostructures
No full textLateral heterostructures built of monolayers of transition-metal dichalcogenides host a thin one-dimensional interface exhibiting a large energy offset. Recently, the formation of spatially separated charge-transfer (CT) excitons at the interface has been demonstrated, but their impact on technologically important exciton propagation across the interface has remained in the dark. In this theoretical work, we microscopically investigate the spatiotemporal exciton dynamics in the exemplary hBN-encapsulated WSe₂–MoSe₂ lateral heterostructure. We reveal a highly interesting interplay of energy-offset-driven unidirectional exciton drift across the interface and efficient capture into energetically lower CT excitons at the interface. This interplay triggers a counterintuitive thermal control of exciton transport with less efficient propagation at lower temperatures, opposite to conventional semiconductors. We predict clear signatures of this intriguing exciton propagation in both far- and near-field photoluminescence experiments. Our results present an advance in the microscopic understanding of technologically relevant unidirectional exciton transport in lateral heterostructures
Singularities of local models
No full textWe construct local models of Shimura varieties and investigate their singularities, with special emphasis on wildly ramified cases. More precisely, with the exception of odd unitary groups in residue characteristic 2 we construct local models, show reducedness of their special fiber, Cohen–Macaulayness and in equicharacteristic also (pseudo-)rationality. In mixed characteristic we conjecture their pseudo-rationality. This is based on the construction of parahoric group schemes over two dimensional bases for wildly ramified groups and an analysis of singularities of the attached Schubert varieties in positive characteristic using perfect geometry