What is OPUS?
Siegen University Library provides a free of charge repository named OPUS Siegen (OPUS = Online PUblication Server) with the purpose to publish, archive and retrieve electronical documents produced at the University of Siegen.
What will you find here?
You will find Open-Access-Publications from all faculties of Siegen University and from the "universi" publishing house. The University Library applies acknowledged quality standards and offers support for publishing your documents.
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For uploading documents, sign on to OPUS via Shibboleth using your ZIMT-Account.
Recently published
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Publication Open Access KI-basierte Entscheidungsunterstützungssysteme für die Antibiotikatherapie im Krankenhaus: Determinanten für die Implementierung aus Perspektive beteiligter Versorgungsakteure(2026-04-04)Background: The potential of artificial intelligence (AI) and AI-based systems for healthcare has steadily increased in recent years. AI-based clinical decision support systems (CDSS) make it possible to rapidly identify patterns within large datasets and generate robust predictions to support clinical decision-making – including in the context of antibiotic therapy. However, hospitals in Germany currently make little use of AI-based CDSS, partly because their implementation is complex. Objective and methods: The aim is to examine the requirements for successful implementation of AI-based CDSS for antibiotic therapy in hospitals from the perspective of healthcare stakeholders, and to derive future research and action needs. Four studies examined determinants of implementation using both quantitative and qualitative research methods. All peer-reviewed publications draw on the structuring elements of the Human–Organization–Technology(HOT)-fit model and to systematically outline facilitators and barriers that determine the implementation process of AI-based CDSS. Results: The imple-mentation of AI-based CDSS involves organizational, user-related, and technology-related measures, with the characteristics of the systems themselves representing key determining factors. In particular, usability, interoperability, recommendation quality, and system transparency set the course for successful implementation. At the organizational level, real-time-capable infrastructures, readiness for change, resources, as well as political and regulatory frameworks concerning education, responsibility, and financing constitute central requirements. Insufficient readiness for change often results from situational factors, including a perceived lack of need or the complexity of new technologies being considered too high. This may also reflect underlying fears or feelings of being overwhelmed. In addition, the attitudes, knowledge, and perceived clinical benefit among potential users are crucial. At the same time, the boundary between decision support and decision-making requires AI-specific competencies and an ongoing discourse on normative and professional-ethical issues. Conclusion: Implementation processes must take into account organizational structures, cultural and professional norms, as well as social and political factors such as guidelines, laws, and regulations. Interdisciplinary and transdisciplinary approaches are necessary to identify problem areas at an early stage and to anticipate practical as well as ethical challenges.Source Type: - Some of the metrics are blocked by yourconsent settings
Publication Open Access Auslegung eines Hybridverbunds aus UD-faserverstärktem, duroplastischem und kurzfaserverstärktem, thermoplastischem Kunststoff am Beispiel eines hoch beanspruchten Fahrwerkbauteils(2026-06-24)The development of lightweight structures is a complex and interdisciplinary process that inte-grates the fields of design, materials science, and manufacturing engineering. Increasing re-quirements due to e-mobility influence the subcomponents of the chassis directly - higher loads and demands for such lightweight structures with unchanged cost pressure. Hybrid structures were proven to be effective within this context. In the state of the art, different metal-plastic hybrids are presented. The objective of this work is to further advance such hybrid systems by substituting steel with a unidirectional glass-fiber-reinforced thermoset (UD-GFRP). Owing to its high specific strain energy and simultaneously high strength, UD-GFRP is well suited for load-path-optimized structural components. How-ever, the introduction of load transfer elements into such structures is both complex and often accompanied by a reduction in structural performance. By combining the continuously fiber-reinforced thermoset carrier structure with thermoplastic injection-molded material to form a hybrid component, these disadvantages can be largely mitigated. Nevertheless, research gaps remain with respect to the interfacial adhesion of thermoplastic–thermoset hybrids and the influence of surface pretreatment methods. The combination of dissimilar materials in a hybrid structure inherently leads to residual stresses due to differences between the curing or bonding temperature 𝑇𝐻 and the operating temperature 𝑇𝐸. These residual stresses may result in a reduction of the overall bond strength within the hybrid system. For thermoset–thermoplastic hybrids, thermally induced residual stresses have so far only been insufficiently investigated. The intrinsic hybrid structure developed in this work – consisting of a thermoset serving as a stiffening element and a thermoplastic serving as a load introduction element – is designed for application in highly loaded components. The development focuses on three main aspects: First, the bond between thermoset and thermoplastic is examined with particular attention to the adhesion mechanisms and potential methods for their improvement. The second part of the study investigates the residual stresses arising during the thermal manufacturing process are investigated, which result from the mismatch in the coefficients of thermal expansion of the constituent materials. In the final part, the interaction within the hybrid composite is examined using an application-oriented demonstrator. Specifically, it is assessed whether residual stresses can be relieved and how this affects the demonstrator’s service life. Based on the findings, a recommendation for an optimal interface between the thermoplastic and thermoset materials will be provided. Finally, a recommendation is derived for an optimized interface de-sign between thermoplastic and thermoset materials.2 6 - Some of the metrics are blocked by yourconsent settings
Publication Open Access Zirconia Nanotubes as a Potential Coating on Implant Systems for Controlled Drug Release and Bioactivity(2026-07-21)Implant-associated infections and insufficient tissue integration remain central challenges in the development of multifunctional biomaterials. These challenges have driven the need for modern implant systems to evolve from initially bioinert devices into regenerative tools for tissue engineering. It is well established that the implant surface plays a critical role in addressing these challenges. Consequently, significant research efforts have been directed toward optimizing implant surfaces to improve biological performance. The use of nanostructured metal oxides as coatings on implant surfaces has attracted considerable interest in this regard. Increasing evidence suggests that such nanotopographies can enhance cellular responses and act as reservoirs for controlled drug release. This thesis aims to develop and investigate zirconia nanotubes (ZrNTs) based surface coatings as multifunctional implant interfaces, with a focus on controlled drug delivery, antibacterial functionality, and host cell response interactions. ZrNTs with designed morphologies were fabricated via electrochemical anodization by systematically varying anodization parameters. Several simple yet novel structural and chemical modifications were made to the fabricated ZrNT to improve drug-delivery performance, antibacterial properties, and cell-interaction behavior. Structural and chemical characterization was performed using mainly scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time of flight secondary ion mass spectrometry (ToF-SIMS). The main results of this dissertation include ZrNT with a modulated diameter (i.e., a bottleneck-like structure), which was successfully developed to mitigate initial burst drug release and enable an extended-release profile. Incorporation of silver nanoparticles via straightforward anodization of Zr-Ag alloys resulted in ZrNTs with broad–spectrum antibacterial activity. Protein adsorption studies revealed that surface chemistry (specifically, functionalization with hydroxyapatite) and morphology influence protein orientation and denaturation, which, in turn, affect cell–surface interactions. The findings of this thesis demonstrate novel, simple, yet effective approaches toward optimizing the interface between the implant surface and the host environment to meet the critical requirements of biocompatibility and antibacterial properties. This work contributes to the design of smart, multifunctional biomaterials for improved implant performance. It introduces the potential of zirconia nanotubes as a versatile, tunable coating for bioactive, controlled drug-releasing implant surfaces.Source Type:5 4 - Some of the metrics are blocked by yourconsent settings
Publication Open Access Na-K-Sb photocathodes-synthesis, characterization and application in photoinjector(2026-06-12)State-of-the-art and future accelerators such as energy recovery linacs (ERLs), free electron lasers (FELs) and ultra-fast electron diffraction (UED) facilities have increasing demands on the brightness and robustness of the electron source. To meet these requirements, photocathodes are employed in a variety of material systems. Among them, multi-alkali antimonide photocathodes are promising candidates for high-brightness applications due to their high quantum efficiency (QE) and low intrinsic emittance in the visible range. Na–K–Sb photocathodes exhibit QE values comparable to Cs–K–Sb in the visible range, reaching several percent in the green region, while offering superior thermal robustness—a critical attribute for many applications, especially ERLs. Despite these advantages, the widespread adoption of Na–K–Sb photocathodes has been hindered by poor reproducibility and low success rates, stemming from three fundamental challenges: (1) an exceptionally narrow stoichiometric window for high QE, (2) the extremely low equilibrium vapor pressure of sodium required for the high-QE Na2KSb phase, and (3) insufficient control over key deposition parameters, particularly alkali metal flux rates. In this work, these challenges are systematically addressed through the design and commissioning of a new preparation chamber and the development of an optimized triple evaporation method. Through detailed spectral response and X-ray photoelectron spectroscopy (XPS) characterization, the reproducible growth of Na2KSb photocathodes under highly controlled conditions is demonstrated for the first time on substrates suitable for electron accelerators. A control variable approach establishes clear correlations between growth parameters, stoichiometry, and photoemissive properties. Comprehensive analysis of QE homogeneity, supported by a growth model, enables rapid and precise tuning of photoemissive performance. Furthermore, an extensive XPS database is compiled from over 35 Na–K–Sb photocathodes based on their stoichiometry. Finally, the successful operation of a superconducting radio-frequency (SRF) photoinjector using a Na2KSb photocathode is reported, achieving first beam in the SEALab SRF photoinjector.9 5 - Some of the metrics are blocked by yourconsent settings
Publication Open Access Disability and Social Protection in Ghana(2026)The book offers valuable insights into contemporary debates on disability and the development of social protection systems in Ghana and other countries of the so-called Global South, addressing perspectives that have received limited attention in existing scholarship. By integrating historical perspectives and contemporary philosophical debates on African conceptions of community, personhood, reciprocity, and social justice with resource theories and empirical evidence, the author develops a nuanced framework for understanding the relationship between public and indigenous social protection. Based on the experiences and perspectives of users with disabilities, the study offers new insights into the complementarity of state and indigenous social protection structures and their significance for inclusive development. Over the past decades, public social protection has emerged as a critical pillar of the international development discourse. Social protection programmes in countries of the so-called Global South have undergone systematic expansion, driven by multilateral and bilateral development agencies. This trajectory is also evident in Ghana, where a neoliberal approach to social protection, centred primarily on targeted transfers for specific groups, was established in the wake of structural adjustment programmes in the 1980s and 90s. Among other critiques, it has been challenged for isolating vulnerability from the broader systemic processes that have produced the very conditions it seeks to address. At a practical level, this meta-critique is closely connected to the issue of context responsiveness in social protection schemes, a concern that lies at the core of this study's research focus. Ghana’s current social protection schemes operate predominantly as economic interventions, often overlooking other forms of resources that complement economic support and are essential for sustaining livelihoods. This study focuses on these diverse resource forms, as well as the dynamics and institutional rules that govern their access, exchange and conservation. While social protection interventions are typically designed on the assumption that they align with the individual resource arrangements and needs of their intended beneficiaries, empirical evidence suggests only a weak correlation between externally defined resource perspectives and individuals’ subjective assessments of their resource situations. This discrepancy poses a significant challenge for the design and implementation of social protection schemes. The study examines selected public social protection programmes in Ghana – the Disability Common Fund, Livelihood Empowerment Against Poverty (LEAP), and the National Health Insurance Scheme (NHIS) – and their implications for the livelihoods of persons with disabilities. Drawing on qualitative interviews with programme users, disability advocates, and social welfare practitioners, it explores the explicit and implicit assumptions about beneficiaries’ individual resource arrangements that shape design and implementation practices of these programmes. It analyses the demands these assumptions place on recipients and assesses the extent to which they align with beneficiaries’ lived realities and perspectives.6 6
