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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Sonderforschungsbereiche 1595

Aktuellste Veröffentlichungen

Sample size calculation under nonproportional hazards using average hazard ratios
(Wiley, 2024-08-12) Dormuth, Ina; Pauly, Markus; Rauch, Geraldine; Herrmann, Carolin
Many clinical trials assess time-to-event endpoints. To describe the difference between groups in terms of time to event, we often employ hazard ratios. However, the hazard ratio is only informative in the case of proportional hazards (PHs) over time. There exist many other effect measures that do not require PHs. One of them is the average hazard ratio (AHR). Its core idea is to utilize a time-dependent weighting function that accounts for time variation. Though propagated in methodological research papers, the AHR is rarely used in practice. To facilitate its application, we unfold approaches for sample size calculation of an AHR test. We assess the reliability of the sample size calculation by extensive simulation studies covering various survival and censoring distributions with proportional as well as nonproportional hazards (N-PHs). The findings suggest that a simulation-based sample size calculation approach can be useful for designing clinical trials with N-PHs. Using the AHR can result in increased statistical power to detect differences between groups with more efficient sample sizes.
Shape‐complementary multicomponent assembly of low‐symmetry Co(III)salphen‐based coordination cages
(Wiley, 2024-04-04) Zhang, Bo; Lee, Haeri; Holstein, Julian J.; Clever, Guido H.
While metal-mediated self-assembly is a popular technique to construct discrete nanosized objects, highly symmetric structures, built from one type of ligand at a time, are dominating reported systems. The tailored integration of a set of different ligands requires sophisticated approaches to avoid narcissistic separation or formation of statistical mixtures. Here, we demonstrate how the combination of three structure-guiding effects (metal-templated macrocyclization, additional bridging ligands and shape-complementarity) based on Co(III)salphen metal nodes allows for a rational and high-yielding synthesis of structurally complex, lantern-shaped cages with up to four differentiable bridges. Three new heteroleptic coordination cages based on dinuclear Co(III)salphen macrocycles were synthesized in a one-pot reaction approach and fully characterized, including single crystal X-ray analyses. One cage groups two of the same ligands, another two different ligands around a symmetric Co2-bis-salphen ring. In the most complex structure, this ring is unsymmetric, rendering all four connections between the two metal centers distinguishable. While heteroleptic assembly around Pd(II) nodes has been shown to be dynamic, beneficial for cage-to-cage transformations, assembly cascades and adaptive systems, the herein introduced cages based on kinetically more inert Co(III)salphen will be advantageous for applications in enzyme-like catalysis and molecular machinery that require enhanced structural and chemical stability.
Shape sensitivity analysis of history‐dependent materials for dynamic structures
(Wiley, 2024-12-30) Ghasemi, Seyed Ali; Barthold, Franz‐Joseph
This work presents a sensitivity analysis of inelastic material behavior within dynamic structures. The primary focus is on using the direct differentiation method to derive sensitivity matrices for displacement, velocity, acceleration, and history variables. These methods are validated through a detailed academic example.
More durable modular expansion joint constructions for road bridges
(Wiley, 2024-09-11) Ungermann, Dieter; Brune, Bettina; Diener, Michael
Relevant aspects in the design of modular expansion joints are the high fatigue stress caused by heavy load traffic and the corrosion protection. Currently, corrosion damage is often not limited to the traversable surface. Therefore, more durable expansion joints are highly desirable to extend their service life. The FOSTA research project P1574 resulted from the need for durable expansion joints and thus is aimed at hot-dip galvanized structures. In this project about 14.000 individual damages on 6.300 modular expansion joints were evaluated, relevant hot-dip-galvanizing parameters were investigated and recommendations for hot-dip galvanizing-compatible constructions were made. In addition, the fatigue strength of existing constructions has been evaluated with regard to the current and upcoming version of Eurocode 1993-1-9. This evaluation will be verified in the course of cyclic tests and numerical investigations. A monitoring concept is to be designed according to the requirements of the modular expansion joints and the corresponding neuralgic points.
Supramolecular interactions as key in racemic resolution
(Wiley, 2024-09-02) Kirchhoff, Jan‐Lukas; Strohmann, Carsten
A highly selective approach with high yields of two diastereomeric silicon-stereogenic menthoxysilanes, (RSi)-3 and (SSi)-3, introduced by Sommer et al., could be established as well as investigated in detail using different analytical tools. Single-crystal X-ray diffraction analysis was used to examine the different crystallization rates while Hirshfeld surface analysis was applied to extend supramolecular interactions in the solid state which showed stronger hydrogen bridges for the faster crystallizing diastereomer (SSi)-3. In addition, similar ground-state energies haven been found for both diastereomers by DFT calculations. Subsequent NMR studies showed stable Si-configurations wherein epimerization only started after more than 4 hours at 110 °C. Access to both diastereomers with opposite configuration at the stereogenic silicon center is achievable in high yields and high stereochemical purity using only naturally occurring (−)-menthol as a reagent.