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Directed self-assembly of the organic semiconductor C8-BTBT-C8 in anodic aluminum oxide nanopores
No full textControlling the self-assembly of organic semiconductors at the nanoscale is critical for advancing high-performance electronic and photonic devices, yet it remains challenging due to their intrinsic anisotropic crystallization and sensitivity to processing conditions. Here, we demonstrate that cylindrical nanoconfinement within anodic aluminum oxide membranes provides a versatile platform to precisely tune the molecular orientation and phase behavior of the prototypical organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT-C8). Combining temperature-dependent high-resolution synchrotron X-ray scattering with optical birefringence measurements, we uncover that confinement geometries (pore diameters 25–180 nm) and surface chemistry govern the emergence of distinct smectic A textures, featuring molecular layers either parallel or perpendicular to the pore axis. The competition between axial and radial smectic layering is modulated by pore size, surface hydrophilicity, and thermal history, enabling reversible control over domain orientations and transitions between liquid crystalline and crystalline states. Notably, nanoconfinement stabilizes the smectic phase over an expanded temperature range compared to bulk, while inducing complex multidomain configurations owing to geometric constraints and anchoring conditions. Our results elucidate fundamental mechanisms by which anisotropic nanoscale confinement directs the self-organization of highly conjugated organic molecules, with implications for optimizing directional charge transport and anisotropic optical responses in organic–inorganic hybrid nanoarchitectures. This study establishes nanoconfinement as a powerful strategy to engineer morphology and functional properties in organic semiconducting materials with nanoscale precision
Adaptive tolerances for staggered solution algorithms in fluid-structure interaction
No full textStaggered solution algorithms are a well-known alternative to monolithic approaches for solving strongly coupled multi-field problems. A coupling between the subproblems is achieved by exchanging coupling quantities between the solvers. Implicit coupling schemes are realized by letting the solvers solve each load or time step repeatedly until convergence up to a given coupling tolerance is achieved. In fluid-structure interaction as well as a variety of other problem classes, the equations governing the individual fields are nonlinear. Accordingly, each solver performs an inner iterative solution procedure that terminates once an inner tolerance is reached. The basic idea of this work builds on the possibility to adaptively adjust these inner tolerances based on carefully designed rules while preserving the black-box nature of the solvers. The resulting coupling scheme yields significant improvements in computational efficiency compared to classical schemes where the inner solver tolerances are held fixed. This is demonstrated in several numerical examples. The idea is tested in combination with state-of-the-art convergence acceleration schemes and can be realized within any staggered solution approach by only minor modifications to the participating solvers.</jats:p
Back to the Roots: Assessing Mining Techniques for Java Vulnerability-Contributing Commits
No full textContext: Vulnerability-contributing commits (VCCs) are code changes that introduce vulnerabilities. Mining historical VCCs relies on SZZ-based algorithms that trace from known vulnerability-fixing commits. Objective: Although these techniques have been used, e.g., to train just-in-time vulnerability predictors, they lack systematic benchmarking to evaluate their precision, recall, and error sources. Method: We empirically assessed 12 VCC mining techniques in Java repositories using two benchmark datasets (one from the literature and one newly curated). We also explored combinations of techniques, through intersections, voting schemes, and machine learning, to improve performance. Results: Individual techniques achieved at most 0.60 precision but up to 0.89 recall. The precision rose to 0.75 when the outputs were combined with the logical AND, at the expense of recall. Machine learning ensembles reached 0.80 precision with a better precision–recall balance. Performance varied significantly by dataset. Analyzing “fixing commits” showed that certain fix types (e.g., filtering or sanitization) affect retrieval accuracy, and failure patterns highlighted weaknesses when fixes involve external data handling. Conclusion: Such results help software security researchers select the most suitable mining technique for their studies and understand new ways to design more accurate solutions
Transparent reporting of AI in systematic literature reviews: development of the PRISMA-trAIce checklist
No full textBackground: Systematic literature reviews (SLRs) build the foundation for evidence synthesis, but they are exceptionally demanding in terms of time and resources. While recent advances in artificial intelligence (AI), particularly large language models, offer the potential to accelerate this process, their use introduces challenges to transparency and reproducibility. Reporting guidelines such as the PRISMA-AI (Preferred Reporting Items for Systematic Reviews and Meta-Analyses–Artifi-cial Intelligence Extension) primarily focus on AI as a subject of research, not as a tool in the review process itself. Objective: To address the gap in reporting standards, this study aimed to develop and propose a discipline-agnostic checklist extension to the PRISMA 2020 statement. The goal was to ensure transparent reporting when AI is used as a methodological tool in evidence synthesis, fostering trust in the next generation of SLRs. Methods: The proposed checklist, named PRISMA-trAIce (PRISMA–Transparent Reporting of Artificial Intelligence in Comprehensive Evidence Synthesis), was developed through a systematic process. We conducted a literature search to identify established, consensus-based AI reporting guidelines (eg, CONSORT-AI [Consolidated Standards of Reporting Trials–Arti-ficial Intelligence] and TRIPOD-AI [Transparent Reporting of a Multivariable Prediction Model of Individual Prognosis or Diagnosis–Artificial Intelligence]). Relevant items from these frameworks were extracted, analyzed, and thematically synthesized to form a modular checklist that integrated with the PRISMA 2020 structure. Results: The primary result of this work is the PRISMA-trAIce checklist, a comprehensive set of reporting items designed to document the use of AI in SLRs. The checklist covers the entire structure of an SLR, from title and abstract to methods and discussion, and includes specific items for identifying AI tools, describing human-AI interaction, reporting performance evaluation, and discussing limitations. Conclusions: PRISMA-trAIce establishes an important framework to improve the transparency and methodological integrity of AI-assisted systematic reviews, enhancing the trust required for the responsible application of AI-assisted systematic reviews in evidence synthesis. We present this work as a foundational proposal, explicitly inviting the scientific community to join an open science process of consensus building. Through this collaborative refinement, we aim to evolve PRISMA-trAIce into a formally endorsed guideline, thereby ensuring the collective validation and scientific rigor of future AI-driven research
Mechanical behavior of nanoporous gold functionalized with surface oxide and organic films
No full textThis thesis investigates functional mechanical properties of smart stimuli-sensitive hybrids based on nanoporous gold and organic layers. As a metal skeleton, unimodal and hierarchical nanoporous nested networks fabricated via an electrochemical dealloying were employed. Three electrochemistry-inspired approaches are integrated to surface modification of nanoporous gold – reversible capacitive assembly of ionic charges in the electric double layer, electrosorption of oxygen-species, and chemisorption of electroactive ferrocene-terminated alkanethiol self-assembled monolayers. To probe functionalities such as actuation and tunable stiffness, in situ experiments are carried out in electrochemical environment. In situ dilatometry is employed to investigate the impact of the electrochemicallycontrolled interface on the actuation behavior of the hybrids. The findings demonstrate remarkable differences in the strain responses of the materials with respect to the pore morphology and surface state. The contribution of the surface stress to the reproducible macroscopic actuation is experimentally confirmed for all hybrids under study. The negative values of the electrocapillary coupling parameters are determined pointing to the compressive surface stress in the metal surface upon the capacitive charging and
electrosorption of oxygen-species. In nanoporous gold modified with the ferrocene-bearing self-assembled molecules, the actuation strain non-linearly scales with the ferrocene surface fraction testifying to the impact of the redox-events in the monolayer on the macroscopic actuation of the nanoporous network. The estimation of the mean actuation coefficient in the hybrids
with the electroactive self-assembled monolayers pointed out to an enhanced strain response compared to those induced by conductive polymers. Along with actuation, the thesis explores the size-dependence of the effective elastic modulus of the hybrids via in situ dynamic mechanical analysis. Experimental observations in this study at a structural size below 100 nm support a hypothesis that the effective elastic behavior is dominated by the surface excess elasticity at this scale when specific adsorption is involved. Subsequently, the electro-elastic coupling parameters
have been estimated for bulk nanoporous networks. Overall, this thesis discusses the electro-chemo-mechanical coupling in the nanoporous hybrids. It demonstrates that hierarchical nanoporous gold serves as a robust platform for enhancing the functional properties of nanoporous materials. Incorporating organic films allows nanoporous gold to convert chemical processes into mechanical motion, paving the way for further research and practical applications of nanoscale materials with tunable properties.In dieser Arbeit wird die elektrochemisch-mechanische Kopplung in nanoporösem Gold mit unterschiedlicher Porosität erforscht, das mit anodischen Oxiden und redoxaktiven ferrocenhaltigen selbstorganisierten Alkanethiol-Monolagen modifiziert ist. Die mechanische Betätigung und die schaltbare Steifigkeit dieser Hybride werden durch in situ Experimente in Elektrolyt untersucht. Die Ergebnisse zeigen signifikante Unterschiede in den Reaktionen in Abhängigkeit von einem nanoporösen Metallskelett und seinem Oberflächenzustand. Die Ursprünge dieser Phänomene werden in der Dissertation diskutiert. Insgesamt unterstreicht diese Arbeit das Potenzial des hierarchischen nanoporösen Goldes, das mit elektroaktiven Monoschichten modifiziert wird, als vielseitige Plattform für die Verbesserung der funktionellen Eigenschaften von Materialien im Nanomaßstab und eröffnet Wege für innovative Anwendungen in reizempfindlichen Systemen.Deutsche Forschungsgemeinschaft (DFG
Interface engineering and Oxygen vacancy control in SrTiO₃-TiO₂ eutectics
No full textThe development of highly efficient semiconducting materials is essential for achieving the high-yield and stable hydrogen and/or oxygen evolution reactions (HER/OER) in photoelectrochemical (PEC) water splitting reactions. The SrTiO₃-TiO₂ eutectic compound has recently emerged as a perspective material with extraordinary activities in the PEC field due to the unique crystallographic and electronic properties caused by the large number of oxygen vacancies in the bulk. In the present study, different experimental techniques (XPS, SEM/EDX, TEM/EDX) are used to provide a detailed investigation of the changes in the structural and electronic properties of the SrTiO3-TiO2 eutectic upon annealing under various gaseous environments (in vacuum, air, oxygen, argon). These results demonstrate that thermal annealing in different environments significantly enhances the formation of a sharp interface between the two crystalline phases and allows to control the concentration of the oxygen vacancies within the eutectic material
Single sided water absorption in thick GFRP structures: Mechanical effects and diffusion monitoring by integrated smart sensors
No full textIn many application scenarios, such as the wind energy industry, fibre-reinforced polymers undergo atmospheric ageing due to prevailing environmental conditions. As a result, moisture gradients are often present in the material, which influence the material behaviour and mechanical properties. Reliable determination of the current moisture condition at various points in the component and knowledge of the effects of moisture on the mechanical behaviour of the structure can extend the service life and prevent failure. Consequently, this work presents a method for monitoring local moisture absorption and moisture-induced damage in thick GFRP laminates. Therefore, an integrated sensor system based on single carbon fibre (CF) rovings and impedance measurements was developed. Water absorption leads to a change in the dielectric properties of the GFRP, resulting in a significant increase in the phase angle and a simultaneous decrease in the amplitude of the electrical impedance, especially when local fibre-matrix debonding occurs. In addition, the mechanical effects of non-symmetric water absorption are evaluated using four-point bending and interlaminar shear strength tests. The mechanical performance of the aged laminates decreased significantly, even though the water infiltrated the laminates by less than 25 % of the thickness
Increasing tree canopy lowers urban air temperature by up to 1.5 °C in heat-prone areas
No full textUrban heat islands (UHIs) exacerbate thermal stress, disproportionately affecting communities with limited tree cover. While satellite-derived land surface temperature (Ts) is widely used to assess urban heat, it often overestimates conditions compared to air temperature (Ta)—the metric more relevant to human thermal comfort. Despite this discrepancy, relatively few studies have leveraged Ta to quantify the cooling effect of tree canopy in heat-prone areas. Using a citywide network of high-accuracy air temperature sensors and high-resolution satellite data during a heatwave, we first show that surface UHI (SUHI) overestimates urban heat by a factor of two, with SUHI averaging 8.9 °C ± 1.2 vs 4.6 °C ± 1.1 for canopy UHI. We find that tree canopy cover is the dominant cooling factor, explaining 67% of the spatial variation in Ta. Notably, a 10% increase in tree canopy reduces air temperature by 0.8 °C, while a 30% increase lowers it by as much as 1.5 °C. These findings underscore the essential role of urban greening in mitigating extreme heat, reinforcing the need for targeted tree-planting strategies in vulnerable neighborhoods. By bridging remote sensing with in-situ temperature observations, our study highlights the urgency of integrating air temperature–based UHI assessments into urban planning and climate adaptation policies. Expanding tree canopy coverage is a scalable, nature-based solution for enhancing urban resilience, and this work directly quantifies its impacts
6G sub-networks: from use cases and requirements to concept and architecture
No full textThe 6th generation of wireless mobile networks (6G) is envisioned to extend the capabilities of cellular communication networks into new dimensions, such as sensing, integration of artificial intelligence, and integration of other networking technologies. In addition, 6G is often described as the generation that will be the “Network of Networks” (NoN). One of the NoN building blocks is provisioning of local connectivity by so called 6G Sub-networks (SNs). Despite the fact that the term “Sub-networks for 6G” is already widely used, it still lacks a clear technical definition. This article aims to address this gap by providing contextualization and a description of the concept from various relevant perspectives such as legacy, autonomy, and topology. Moreover, a concept for an architecture is proposed, including Sub-networks, their interaction with associated user equipment, other Sub-networks and “Parent Networks” (PNs). These concepts are then mapped to a variety of use cases from relevant vertical domains, like vehicular Sub-networks, Sub-networks for collaborative and autonomous robots in factories, remote operation of aircrafts, airplane onboard systems and emergency services. Finally, a comparison of the described Sub-network concept with existing approaches in 3rd Generation Partnership Project (3GPP) is provided, stating similarities, differences, and future requirements for standardization
On the efficiency of explicit and semi-explicit immersed boundary finite element methods for wave propagation problems
No full textImmersed boundary methods have attracted substantial interest in the last decades due to their potential for computations involving complex geometries. Often these cannot be efficiently discretized using boundary-fitted finite elements. Immersed boundary methods provide a simple and fully automatic discretization based on Cartesian grids and tailored quadrature schemes that account for the geometric model. It can thus be described independently of the grid, e.g., by image data obtained from computed tomography scans. The drawback of such a discretization lies in the potentially small overlap between certain elements in the grid and the geometry. These badly cut elements with small physical support pose a particular challenge for nonlinear and/or dynamic simulations. In this work, we focus on problems in structural dynamics and acoustics and concentrate on solving them with explicit time-marching schemes. In this context, badly cut elements can lead to unfeasibly small critical time step sizes. We investigate the performance of implicit-explicit time marching schemes and two stabilization methods developed in previous works as potential remedies. While these have been studied before with regard to their effectiveness in in-creasing the critical time step size, their numerical efficiency has only been considered in terms of accuracy per degree of freedom. In this paper, we eval-uate the computation time required for a given accuracy, which depends not only on the number of degrees of freedom but also on the selected spatial dis-cretization, the sparsity patterns of the system matrices, and the employed time-marching scheme