Eldorado - Repositorium der TU Dortmund

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Bei diesem Service handelt es sich um das Institutionelle Repositorium der Technischen Universität Dortmund. Hier werden Ressourcen aus und für Lehre, Studium und Forschung gespeichert, erschlossen und der Öffentlichkeit zugänglich gemacht.

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Aktuellste Veröffentlichungen

Integrating artificial intelligence in investigating magneto-bioconvection flow of oxytactic microorganisms and nano-enhanced phase change material in H-type cavity
(2024-03-01) Hussain, Shafqat; Aly, Abdelraheem M.; Alsedias, Noura; Çolak, Andaç Batur
Nano-enhanced phase change materials is an effective way to improve the thermal characteristics and to minimize energy consumption. The bioconvection flow of nano-enhanced phase change materials is gaining more attention in recent investigations due to its significant applications in engineering and medical sciences. The present study aims to numerically explore magneto-bioconvection flow of nano-enhanced phase change materials in H-type cavity including oxytactic microorganisms. The cavity is constantly heated from the left and a right wall is maintained at cold temperature. The major focus of the current investigation is analyzing the flow and thermal features of the suspension of nano-enhanced phase change materials and a host fluid. The governing system is reduced to the dimensionless form by applying the appropriate transformation. Impact of pertinent parameters, porosity, cavity aspect ratio, Darcy, Hartmann, Lewis, Rayleigh, bioconvection Rayleigh numbers, radiation parameter, and Péclet number on bioconvection flow of oxytactic microorganisms in H-type cavity has been analyzed. Six various artificial neural network models are explored in order to estimate critical parameters with an artificial intelligence approach. It is found that the variations of a cavity aspect ratio are enhancing the bioconvection flow and phase change material. Increasing Hartmann number reduces the nanofluid velocity and distributions of oxygen and microorganisms. The Rayleigh and bioconvection Rayleigh numbers are playing an importance role in enhancing bioconvection flow and varying phase change material.As Ha increases from 10 to 100, at γ=900, there is a 1.67% decrease in the values of Nuavg and a 0.247% increase in Shavg. Among the study findings, the developed artificial neural networks can predict each parameter with high accuracy.
Investigating the influence of B, C, and N on the tribo-mechanical properties of the chemically complex TiSiBCN thin films using design of experiments
(2024-12-10) Tillmann, Wolfgang; Urbanczyk, Julia; Ebady, Ahmad Zahid; Thewes, Alexander; Bräuer, Günter; Lopes Dias, Nelson Filipe
TiSiBCN thin films show promising properties like high hardness and improved tribological behavior. Adjusting the chemical composition can tailor the properties of these thin films. To investigate this influence, usually one element is varied. However, the interplay and influence of especially the light elements B, C, and N on the tribo-mechanical properties of chemical complex TiSiBCN thin films remain unclear. Therefore, a design of experiment using a central composite design (CCD) was employed to investigate the influences of these light elements on the tribo-mechanical properties of TiSiBCN thin films. TiSiBCN with varying chemical compositions were grown in a magnetron sputtering process by adjusting the cathode power of TiB2/TiSi2 composite targets and the gas flow rates of C2H2 and N2. X-ray diffraction (XRD) analysis revealed crystalline phases based on Ti, TiN, TiC, and TiB, with varying degrees of crystallinity dependent on the chemical composition, where the TiSiBCN thin films demonstrate a broad spectrum of mechanical properties, with hardness and elastic modulus ranging from 20.2 to 39.7 GPa and from 222.3 to 405.0 GPa, respectively. Notably, the B content significantly affects the mechanical properties, with the highest hardness and elastic modulus observed at 46.0 at.-% B. In tribometer tests against an Al2O3 ball under dry friction at room temperature, the TiSiBCN thin films also exhibit a broad spectrum of tribological properties, with the coefficients of friction (CoF) between 0.62 and 0.89 and wear rates between 6.4 × 10−5 and 12.2 × 10−5 mm3/Nm. The lowest CoF of 0.62 with a wear rate of 7.7 × 10−5 mm3/Nm is obtained for TiSiBCN with high amounts of 31.1 at.-% C and 33.5 at.-% N, while high 31.7 at.-% C and low 11.2 at.-% N contents favor the lowest wear rate of 6.4 × 10−5 mm3/Nm with a CoF of 0.74. The tribological results reveal the significant influence of C and N on friction and wear, with TiSiBCN displaying reduced friction and wear tending to have lower hardness. Consequently, TiSiBCN thin films with either high hardness or enhanced friction and wear performance are attainable by adjusting the chemical composition. Depending on the application requirements, the content of the light elements is decisive for the properties of TiSiBCN thin films. The CCD provides insights into the intricate interplay between the chemical composition and tribo-mechanical performance of TiSiBCN. Adjusting the concentrations of B, C, and N within TiSiBCN is crucial for tailoring the tribo-mechanical behavior to meet the specific requirements of applications.
Incumbent responses to anticipated discontinuous regulatory change: the case of Scope 3 CO2 reporting in the European steel industry
(2024-10-28) Hettler, Maximilian; Graf-Vlachy, Lorenz
Regulatory change can be highly discontinuous for organizations. Yet, despite the vast discontinuous change and institutionalism literatures, our understanding of incumbent behavior in response to anticipated discontinuous regulatory change is limited. To address this issue, we conducted a qualitative analysis in the European steel industry, which is facing prospective discontinuous regulatory change on Scope 3 reporting. Our findings offer new insights into this understudied field by elaborating on incumbents' expectations for the future, their ensuing motivations, and their taken or planned actions. We find evidence for heterogenous adaptation behavior that manifests in three motivational patterns: Incentives for early movers, reasons for hesitation, and disincentives preventing implementation. These patterns are a result of incumbents’ varying expectations of future circumstances, opportunities, and risks, and they lead to different actions incumbents plan or take in response to the anticipated change. Our study contributes to the theoretical understanding of regulatory change as a distinct form of discontinuous change, sheds light on incumbent behavior at an early stage of a discontinuous change prior to its actual occurrence, and highlights that adaptation to a discontinuous regulatory change can have both positive and negative effects on incumbents. Our process model enables practitioners to make more informed decisions in the context of discontinuous regulatory change and policymakers may use our findings to improve the regulatory design process and subsequent compliance. Finally, our study opens up numerous pathways for future research.
Multidimensional strategy enables scalable metabolome diversity in microbial fermentations
(2026-01-29) Lindig, Anton; Fataeri, Makram; Hubmann, Georg; Lütz, Stephan
Natural products (NPs) are critical sources of new drug leads, but their biosynthesis is highly sensitive to bioprocess parameters and environmental conditions, making NP discovery especially susceptible to challenges in achieving robust scalability and reproducibility of the metabolome across various cultivation systems. Here, we identified key factors that improved the metabolic footprint overlap of Streptomyces griseochromogenes across three cultivation systems, i.e. baffled shake flasks (BSF), 48 flower plates (48 FP), and a stirred tank bioreactor (STR), by 50 %. Using the classical scale-up criterion of constant oxygen availability, the metabolic footprints were found to differ considerably, with only an 18 % overlap in mass feature (MF) number. Efforts to improve overlap by varying ethanol concentration in culture medium and oxygen availability resulted in an 18 % increase. Factor analysis of 80 cultivations including variations in bioprocess conditions, growth, and MF detection identified morphology and total MF number, mainly influenced by the cultivation systems, as key factors in metabolic footprint reproducibility. Molecular network analysis revealed that 48 FP and STR share the highest number of molecular clusters. Our findings reveal that only multidimensional optimization unlocks robust metabolome scalability and reproducibility across cultivation systems, paving the way for the discovery of novel NPs.
Light‐activatable ubiquitin for studying linkage‐specific ubiquitin chain formation kinetics
(2024-12-24) Banerjee, Sudakshina; Cakil, Zeyneb Vildan; Gallant, Kai; Boom, Johannes van den; Palei, Shubhendu; Meyer, Hemmo; Gersch, Malte; Summerer, Daniel
Ubiquitination is a dynamic post-translational modification governing protein abundance, function, and localization in eukaryotes. The Ubiquitin protein is conjugated to lysine residues of target proteins, but can also repeatedly be ubiquitinated itself, giving rise to a complex code of ubiquitin chains with different linkage types. To enable studying the cellular dynamics of linkage-specific ubiquitination, light-activatable polyubiquitin chain formation is reported here. By incorporating a photocaged lysine at specific sites within ubiquitin through amber codon suppression, light-dependent activation of ubiquitin chain extension is enabled for the monitoring of linkage-specific polyubiquitination. The studies reveal rapid, minute-scale ubiquitination kinetics for K11, K48, and K63 linkages. The role of individual components of the ubiquitin-proteasome system in K48-initiated chain synthesis is further studied by small molecule inhibition. The approach expands current perturbation strategies with the ability to control linkage-specific ubiquitination with high temporal resolution and should find broad application for studying ubiquitinome dynamics.