Eldorado - Repositorium der TU Dortmund

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Fach- und Universitätsübergreifendes 1320
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Sonderforschungsbereiche 1595

Aktuellste Veröffentlichungen

Torn between realism and guidance in entrepreneurship education
(2026) Wenzel, Anna; Liening, Andreas; Geiger, Jan-Martin
Although experiential entrepreneurship education requires balancing realism and instructional guidance, it remains unclear how these elements should be designed and how concrete design decisions shape individual learning processes. This dissertation examines the design and effects of metaverse-enhanced realism and AI-supported guidance in business simulation games. Drawing on five studies combining Action Design Research, value-added research, and complexity-informed analytics, the findings show that enhanced realism and adaptive guidance do not automatically improve learning processes. Rather, their effects depend on learner characteristics, contextual conditions, and temporal dynamics. Synthesizing these insights, the dissertation develops a Synergetic Model of Experiential Learning Dynamics in Entrepreneurship Education, conceptualizing entrepreneurial learning as a complex, non-linear process emerging from interactions between instructional design, individual learner charactierstics, and context over time.
Essays on expectations and beliefs in labor markets
(2026) Jost, Gregor Bodo; Buchheim, Lukas; Balleer, Almut
This dissertation studies how expectations and beliefs shape labor market behavior and the labor market outcomes that result from this behavior. It focuses on three specific behavioral margins: wage-setting decisions by firms, job application decisions of job seekers, and on-the-job search and job-to-job transition behavior of workers. Across the three chapters, the dissertation combines theoretical models with empirical or experimental analyses that assess central predictions of the models. Chapter 1 studies the pass-through from expected inflation into wage growth in the presence of downward nominal wage rigidity. The chapter develops a model in which firms set wages under uncertainty about future inflation and face constraints on nominal wage cuts. The model shows that downward nominal wage rigidity and inflation uncertainty can reduce the pass-through from expected inflation into wage growth below the level predicted by benchmark wage-setting models. Using survey data from German firms, the chapter provides evidence consistent with the central predictions of the model: the pass-through from expected inflation into expected wage growth is low, decreases with uncertainty about future inflation, and tends to increase with expected long-run inflation. Chapter 2 studies the role of overconfidence in the gender application gap. The chapter develops a model in which job seekers face vacancies that differ in the wages they offer. Overconfidence affects application decisions because it changes perceived hiring chances. The model predicts that gender differences in overconfidence can contribute to gender differences in applications to high-wage vacancies through a direct and an indirect channel. A laboratory experiment provides evidence consistent with the direct mechanism. Chapter 3 studies how present bias affects on-the-job search, job offer acceptance behavior, and wage outcomes. The chapter develops a model in which workers can search for better jobs while employed but face immediate search costs. Present-biased workers search less than time-consistent workers because they overweight current search costs relative to future wage gains. The model also shows that awareness of future present bias affects job offer acceptance behavior. Sophisticated present-biased workers may demand larger wage increases to switch jobs, while naive present-biased workers may accept relatively low offers because they overestimate future search. Descriptive survey evidence is consistent with the predicted differences in acceptance behavior across types.
Development of Zn(II) complexes for efficient triplet emission
(2026) Mitra, Mousree; Steffen, Andreas; Henke, Sebastian
In the recent past, luminophores based on zinc(II) have gained increasing attention as a promising alternative to expensive 4d and 5d metal-based luminophores due to its abundant availability, cost-effectiveness, and stable d10 electron configuration. Despite these advantages, the number of literature-known zinc(II) luminescent complexes that involve emission from triplet excited states is very limited.[1,2] Recent studies on cyclic (alkyl)(amino) carbene (cAAC) complexes of zinc(II) halides demonstrate ultra-long phosphorescence associated with LLCT states.[3] However, these complexes undergo fast photo-induced transformations under continuous high-energy UV irradiation at room temperature, which are linked to asymmetric rotation of the carbene ligand and photo-chemical transformations such as halide dissociation. This doctoral thesis focuses on the chemical modification of cAAC-based zinc halide complexes, such as [Zn2Cl4(MecAAC)2] (41a), to improve photostability and modulate their photophysical properties through halide abstraction and halide exchange routes. Halide abstraction from 41a using a triethylsilylium-like reagent, [Et3Si][B(C6F5)4], results in the formation of a stable tetrameric cluster [(MecAAC)4Zn(μ-Cl)6][B(C6F5)4]2 (42a), while treatment with acetylacetonate or related congeners yields a monomeric complex of the type [(MecAAC)Zn(acac)(Cl)] (43). Both new structural motifs exhibit phosphorescence, but, more importantly, their photostability is significantly improved compared to the starting dimeric structure. These promising results highlight the high structural versatility and tunability of the photophysical properties of rare phosphorescent zinc(II) complexes based on cAAC chromophore ligands. In the second project, an electron-rich dithiophenolate ligand (benzene-1,2-dithiolate) was employed to synthesize the dimeric [(MecAAC)2Zn2(bdt)2] (45), where the dithiophenolate ligand coordinates to the metal center in a bridging mode, providing high stability toward air and moisture.[4] The complex exhibits visible light emission when incorporated into polymer matrices, with a very high radiative rate constant of 1.5×105 s-1. Variable-temperature lifetime measurements reveal TADF emission with a small singlet-triplet energy gap, ∆E_((S_1-T_1 ) )= 79 meV. The long-lived excited state was also explored for its potential in Dexter energy transfer, and it was found to be faster than the standard [Ru(bpy)3]2+ in the photo-isomerization of E-stilbene. Although the major disadvantage of this complex lies in its weak photo-efficiency, with the highest value of photoluminescence quantum yield being only 0.10 in a PMMA matrix, it still shows potential for further optimization. To overcome the drawbacks of the previous dimeric Zn(II)-bridged dithiophenolate complex, sterically more demanding menthyl-substituted cAAC ligands were employed to synthesize the next generation of zinc(II) TADF emitters, referred to as CZTs (carbene-zinc-thiolate).[5] The CZTs exhibit bright yellow-orange luminescence in the solid state, with photo-efficiency enhanced by 6-15 times compared to the previous dimer. Additionally, structural control over the excited-state properties of CZTs is achieved by isolating different polymorphs of CZT3. Detailed photophysical studies and quantum mechanical calculations reveal that the dihedral angle (Ω) between the carbene and the S-Zn-S unit controls the relative rates of kISC and krISC, thus influencing the TADF efficiency. The tilted conformation (Ω= 33-36°) in CZT3 is found to be the most efficient orientation, leading to a radiative rate constant (kᵣ) of up to 1.2×106 s-1 at room temperature — a record value for zinc(II)-based emitters, even competitive with well-established rare-metal-based emitters. The next work presents a systematic development of Zn(II)-based carbene–thiolate complexes as efficient thermally activated delayed fluorescence (TADF) emitters using rigid bicyclic (BicAAC) ligands. Structural tuning from monomeric to dimeric architectures enables control over geometry, rigidity, and ligand-to-ligand charge transfer (LLCT) excited states. The complexes exhibit weak emission in solution but show near-unity quantum yield (ΦPL up to 0.9) in the solid state due to suppressed non-radiative decay. Temperature- and environment-dependent studies confirm efficient TADF governed by small singlet–triplet energy gaps and optimal dihedral angles.
Systematic investigation of Natural Killer cell stimulation by different activating ligands
(2026) Kröll, Luca; Watzl, Carsten; Zimmer, Philipp
Natural Killer (NK) cells play a pivotal role in immune responses against virally infected or transformed cells. Their activation depends on the stimulation of a broad range of receptors. In the presented work, different aspects of NK cell activity were investigated following co-incubation with murine NIH3T3 cells expressing defined human NK cell ligands to identify the role of individual receptor-ligand interactions. B7H6, MICA, and CD20-bound obinutuzumab engaging NKp30, NKG2D, and CD16, respectively, were revealed to be potent inducers of NK cell activity. Combination with 2B4-ligand CD48 significantly increased degranulation and cytokine secretion in engaged NK cells. Following co-incubation with respective targets, expression levels of multiple receptors were down-regulated in a ligand-specific manner, while CD16 and NKp46 surface levels were reduced based on NK cell activation by any ligand. Co-stimulation via 2B4 in combination with either NKp30, NKG2D, or CD16 significantly enhanced the frequencies of serially degranulating NK cells. Taken together, this systematic investigation provides vital insights into NK cell stimulation that may contribute to the development o
Nucleosome remodelling during resection of genomic DSBs and deprotected telomeres in yeast
(2026) Deiser, Anja; Pfander, Boris; Mutschler, Hannes
DNA end resection is a decisive step in the repair of DNA double-strand breaks (DSBs): degradation of the 5′-terminated strands generates 3′ single-stranded DNA (ssDNA) and commits repair to homologous recombination. The core resection enzymes are well characterised, but how resection proceeds through chromatin remains incompletely understood. This thesis investigated how nucleosome remodellers influence long-range resection at AsiSI-induced DSBs and at deprotected telomeres in budding yeast. Strand-specific sequencing was used to measure resection at AsiSI-induced DSBs in yeast strains deficient in nucleosome editing. To compare the mutant strains, cutting efficiencies need to be similar. Therefore, a nanopore-based workflow was used to quantify AsiSI cutting efficiency in parallel. The arp8Δ strain, in which INO80 activity is impaired, showed similar cutting efficiency compared to the control and no significant changes in resection were observed. Data of a strain deficient in SWR1 complex activity and H2A.Z remains inconclusive,as DSB induction was insufficient. Upon complete loss of nucleosome editing activity, cutting efficiency was restored and resection was found to be similar as in control cells. Therefore, nucleosome editing seems to be dispensable for resection. To analyse resection independently of restriction-enzyme cutting, the temperature sensitive cdc13-1 system was used. In cdc13-1 mutants, telomeres get deprotected at restrictive temperatures, leading to activation of the DNA damage response. By quantification of singlestranded DNA (QAOS), we showed that besides Exo1 also Dna2 contributes to long-range resection at telomeres. Thus, long-range resection appeared to be similar at telomeres and DSBs and we investigated the influence of nucleosome remodeller mutants on long-range resection at deprotected telomeres. Depletion of the nucleosome-eviction complexes RSC or SWI/SNF strongly impaired resection, whereas impaired INO80 function or combined loss of SWR1 and H2A.Z had no significant effect. Together, these findings indicate that nucleosome eviction, rather than histone-variant exchange, is critical for efficient long-range resection and establish cdc13-1 telomere deprotection as a complementary model for studying long-range resection.