OPUS - Publikationenserver der Technischen Hochschule Nürnberg Georg Simon Ohm
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Insight into the formation of carbon-doped titanate nanotubes
No full textThe formation of carbon-doped titanate nanotubes has been studied by using a simplified synthesis approach and extracting samples at different stages during the formation. The hydrothermal synthesis was conducted in a rotary evaporator with a PFA flask under ambient conditions. The resulting samples have been analyzed regarding their morphology, structure and surface area using X-ray diffraction, scanning electron microscopy and gas adsorption measurements. The results show the formation of high surface area nanosheets after a synthesis time as short as 2 h. Even though the surface area at this stage has already reached 212 m2/g, a change in morphology to elongated structures is not observed until 4 h of synthesis, suggesting the formation of the nanotubes during this phase. From that moment on, the d100 value, corresponding to the layer spacing between the nanotube layers, is further decreasing. Additionally, the formation of bundles with longer synthesis times was observed. This effect is discussed to be caused by a self-assembly process of nanotubes assisted by the continuous rotation of the flask in the rotary evaporator. The analysis of the final sample after 24 h revealed remaining carbon shells from the precursor powder. The presence of Ti–O–C bonds observed by X-ray photoelectron spectroscopy proved the incorporation of carbon in the nanotube structure
Spatially Resolved Differentiation of Functional Degradation and Perforating Structural Defects in Membrane Electrode Assemblies Using Diffusion-Cell Coupled DC-SECM
No full textIn order to increase the lifetime of polymer electrolyte membrane (PEM) fuel cells (PEMFCs) and water electrolyzers (PEMWEs), understanding local degeneration processes in membrane electrode assemblies (MEAs) is crucial. By a combination of scanning electrochemical microscopy (SECM) with a flow-through diffusion cell (DiffC-DC-SECM) and ferrocyanide and protons as redox mediators, a spatially resolved analytical method was developed that can differentiate between different functional and structural degeneration phenomena in the aging process of a membrane. An SECM scan at cathodic potential detects the diffusion of protons through the membrane and thus its through-plane proton conductivity, while a second SECM scan at anodic potential visualizes the diffusion of the iron complex through the membrane, thus perforating structural damage such as cracks and holes. The method was successfully validated for the spatially resolved differentiation of membrane
damage in pristine PEMs and catalyst-coated membranes (CCMs) with artificial holes, chemically aged CCMs, and MEAs in fully assembled operational PEMFCs aged by an open-circuit voltage membrane accelerated stress test. DiffC-DC-SECM thus provides a powerful technique with high local resolution for membrane integrity testing under realistic operation conditions to develop long-term durable materials for PEMFCs and PEMWEs
SafeRoute: Adaptive Model Selection for Efficient and Accurate Safety Guardrails in Large Language Models,
No full textDeploying large language models (LLMs) in real-world applications requires robust safety guard models to detect and block harmful user prompts. While large safety guard models achieve strong performance, their computational
cost is substantial. To mitigate this, smaller distilled models are used, but they often underperform on “hard” examples where the larger model provides accurate predictions. We observe that many inputs can be reliablyhandled by the smaller model, while only a small fraction require the larger model’s capacity. Motivated by this, we propose SafeRoute, a binary router that distinguishes hard examples from easy ones. Our method selectively applies the larger safety guard model to the data that the router considers hard, improving efficiency while maintaining accuracy compared to solely using the larger safety guard model. Experimental results on multiple benchmark datasets demonstrate that our adaptive model selection significantly enhances the trade-off between computational cost and safety performance, outperforming relevant baselines
Nutzendenperspektiven auf das Intelligente Hochschulassistenzsystem HAnS: Ergebnisse der qualitativen Evaluation
No full textReducing the child penalty by incentivizing maternal part-time work?
No full textGovernments worldwide are discussing ways to increase maternal labor market participation and to reduce the child penalty. This study analyzes the long run effects of a paid parental leave reform in Germany, a country characterized by high rates of maternal part-time employment after childbirth. The reform introduced additional financial incentives for mothers to engage in part-time work during the first two years following childbirth. Using German social security records, we exploit the fact that only mothers whose child is born in or after July 2015 are eligible for the new part-time parental leave option in a Difference-in-Differences strategy. We find that the policy increased the probability that high-income mothers return to work during the first year after child birth by 2.1–2.8 percentage points ( 15%–20%). However, the policy does not affect maternal employment along the extensive or intensive margin (part-time or full-time work) in the long run (i.e. up to 4.5 years after child). This indicates that while the reform successfully encourages early part-time return to work among high-income mothers, it does not significantly reduce the child penalty. However, it does also not trap mothers in part-time employment
Simulation und Leistungsprognose eines geschlossenen Loop-Tiefengeothermiesystems im Großraum Nürnberg
No full textAusgehend vom geschlossenen Tiefengeothermie-Schema auf dem Deckblatt untersucht diese Arbeit die stationäre Wärmeleistung eines 8 km langen Doppelbohr-Loops unter Nürnberger Randbedingungen. Ein numerisches 1-D-Modell koppelt den radialen Wärmestrom des Untergrunds mit der Rohrströmung und berechnet Temperaturprofile für Speicherradien von 35 m und 70 m. Bei einem thermosiphontauglichen Massenstrom von 36 kg/s liefert der Loop rund 16 MW Nutzwärme; bis etwa 60 kg/s wächst die Leistung nahezu proportional, danach flacht die Kennlinie deutlich ab. Die Vergrößerung des Betrachtungsradius erhöht das verfügbare Felsvolumen um das Vierfache, senkt aber die Momentanleistung nur marginal. Damit kann das System wahlweise auf maximale Laufzeit oder minimierten Ausbauaufwand optimiert werden und erfüllt in beiden Fällen die Fernwärme-Vorgabe von 15 MW
Zur Personalsituation in der niedrigschwelligen Wohnungslosenhilfe als anerkennungsloser und unterschätzter Raum Sozialer Arbeit
No full textDer Beitrag beleuchtet die Personalsituation in der niedrigschwelligen Wohnungslosenhilfe auf Basis qualitativer Interviews mit Fach- und Hilfskräften. Im Zentrum steht die ambivalente Funktion (pädagogischer) Hilfskräfte, die in Folge personeller Unterausstattung zentrale Aufgaben der Sozialen Arbeit übernehmen – etwa Beziehungsarbeit, Beratung und Krisenintervention – dabei jedoch häufig schutzlos, allein und ohne professionelle Anleitung agieren. Die Autor*innen zeigen, dass die Hilfskräfte in einem Raum tätig sind, der von gesellschaftlicher, politischer und organisationaler Nicht-Anerkennung geprägt ist, gleichzeitig aber durch kreative, nicht formalisierte Praxen im Mangel aufrechterhalten wird. Die niedrigschwellige Wohnungslosenhilfe erscheint so als ein paradoxes Feld: prekär ausgestattet, aber von hoher professioneller Bedeutung – mit der Gefahr der Deprofessionalisierung und dem Potenzial zur Neuverhandlung professioneller Standards. Der Beitrag versteht sich als Plädoyer für mehr strukturelle Absicherung und fachliche Anerkennung dieser zentralen Unterstützungsform Sozialer Arbeit
Influence of different stress types on the mechanochemical CaCO3-synthesis
No full textMechanochemistry is considered a green alternative to conventional wet-chemistry. Several reactions have been reported to be feasible via the mechanochemical route, while detailed insight in the mechanistic background of mechanochemical reactions is still elusive. Certain is a significant role of the mechanical stress applied, but the influence of the stress type is rarely addressed. This study uses different simple setups to apply isolated impact,
compressive and shear stress to the reactants of the mechanochemical CaCO3-synthesis. Measuring of the energy inputs and modelling of the stressing conditions allowed correlation of the specific energies in the setups with the chemical conversion of the inorganic model reaction. For the same specific energy, impact stressing was found to be most successful in yielding product and the stress intensity could be identified to play a crucial role. A lower stress intensity was beneficial during initiation of the reaction, whereas a progressed reaction state could take advantage of higher stress intensities. This change is ascribed to the energy utilisation, which is limited in the
beginning, but rises in an advanced reaction state due to the formation of product layers and an increased local temperature. Based on the results, a hypothesis on the influencing factors and procedure of the mechanochemical
CaCO3-synthesis was formulated
The implementation of take-home naloxone: Lessons learned from a 3-year take-home naloxone project in Germany
No full textBackground
Take-home naloxone (THN) can prevent deaths related to opioid overdoses. Despite the first THN project in Germany in 1998, the availability of naloxone for people who use opioids (PWUO) is still scarce. We present the results of the German-wide THN-project NALtrain, which aimed to implement THN nationwide. Firstly, we present data collected during NALtrain and secondly, we use this data to critically reflect on the project and thereby draw conclusions that could inform future THN projects.
Method
NALtrain was conducted between July 2021 and June 2024. Descriptive statistical analysis of the documentation of 74 train-the-trainer events and following naloxone trainings conducted by the trained staff were carried out.
Results
864 staff members from approximately 373 organizations (mainly harm reduction services) participated in 74 train-the-trainer courses. Of the 373 organizations 123 conducted 784 naloxone trainings for PWUO and reached 2,333 PWUO, of whom 1,451 received THN. The goal of training 800 staff members was met, while the goals of reaching 400 organizations and 10,000 PWUO were missed. The implementation of THN is unevenly distributed across the German federal states, especially concentrated in Bavaria. The core learnings are that the prescription-only status of THN leads to extra organizational efforts and hinders the availability of THN for individuals with the highest risk of overdose.
Conclusion
Considering the proportion of organizations offering THN, they can still be classified as “early adopters”. These may serve as role models for the broader majority. Free available THN and centrally coordinated support of implementation including recurring follow-up can be key to a broader availability of THN in Germany. In future initiatives physicians and medical settings should be prioritized