美因茨约翰内斯·古腾堡大学

Strätlingite (Ca2Al2SiO2(OH)10·2.25H2O), a mineral rarely found in nature, which is believed to be responsible for their long-term stability due to its lamellar microstructure that hinders crack propagation along the interfaces between the constituents of concrete. However, the identification of the mineral during early hydration times is often complicated by low crystallinity and absence of a reliable disorder-free structural model. Published crystal structures of strätlingite often contain positionally-disordered atoms in both brucite-like layer and half-occupied double-tetrahedra (DT) layers. In this work we reinvestigate the average structure of strätlingite combining bulk high resolution powder X-ray diffraction (XRPD) and 3D electron diffraction (3D-ED), demonstrating that the R3¯ space group describes the brucite-like layer of strätlingite more appropriately than R3¯m, without positional disorder of the oxygen atoms. Partial occupation in the DT-layer is addressed via solid state nuclear magnetic resonance (ssNMR) and pair distribution function (PDF) analysis, showing that the condensation of Si(Al)O4 tetrahedra is best described by a Q3 configurational arrangement in the form of deformed double six-membered rings, exhibiting local displacements within the ab-plane.

Herein, we thoroughly investigate the (photo)physical properties and the geometry of the first reported Coulombic dyad, composed of dicationic tris(1,10-phenanthroline)ruthenium(II) and tetraanionic 1,3,6,8-pyrenetetrasulfonate. The mixed dynamic and static quenching behavior of the photoexcited ruthenium complex by the pyrene derivative in water was investigated by time-resolved (laser flash photolysis as well as time-correlated single photon counting) and steady-state emission spectroscopy, highlighting their differences and the importance of accurate models to determine the association constant. Temperature-dependent measurements revealed a decrease in dynamic and static quenching efficiency at elevated temperatures and provided the enthalpy and entropy of ion-pair formation in water. The time constant for intra-ion-pair Dexter energy transfer from the triplet excited state of the metal complex to the organic chromophore was determined to be similar to 87 ps using femtosecond transient absorption spectroscopy. Structural insights were obtained from single-crystal X-ray crystallography and molecular dynamics simulations. The simulations revealed a high persistence of the ion-pair in the ground-state and a dynamic yet geometrically well-defined association. A structural similarity was found between solution and solid-state arrangements, indicating pi-interactions besides Coulombic interactions between the ions. These interactions enable sufficient orbital overlap, rationalizing the observed efficient Dexter energy transfer, which is as fast as in many covalently linked donor-acceptor systems. These in-depth investigations provide a comprehensive picture of structure-property relationships in Coulombic dyads, offering valuable insights for their future design and applications.

Informed citizens play a critical role in deliberative democracy. However, contemporary challenges in the political information environment, including digitalization, fragmentation, and misinformation, can contribute to political information avoidance. This study investigates the predictors of the decision-making process leading to disengagement from information about populism. The Theory of Motivated Information Management (TMIM) was applied to examine the manner in which uncertainty discrepancies give rise to political information avoidance through emotions such as anxiety and hope, as well as citizens' efficacy and outcome assessments. The results of an online survey of 456 German residents indicated that anxiety and hope were indirectly associated with information avoidance through efficacy assessments. In contrast, outcome expectancies were not associated with political information avoidance. This research sheds light on the decision-making processes underlying political information avoidance, providing a promising starting point for theory specification.

Fluorosurfactants are an integral part of many industrial processes due to their unparalleled surface activity and high water and oil repellency and can be found in a wide range of consumer products. However, their lack of biodegradability causes great environmental concern and has led to increased regulatory action in recent years. In the search for alternatives, perfluoropropyl vinyl ether was recently identified as a promising building block with an improved ecological profile regarding degradation and accumulation. Here, we utilized short-chain perfluoropropyl vinyl ether (PPVE) or perfluoromethyl vinyl ether (PMVE) as precursors to construct polyether-based fluorosurfactants through copolymerization with hydrophilic comonomers. Surfactant properties and overall fluorine content per molecule could be easily adjusted by changing the comonomer feed. The surface activity was investigated in aqueous solution via tensiometry and was found to be competitive with both legacy PFAS such as perfluorooctanesulfonic acid and current state-of-the-art small molecule fluorosurfactants (gamma stat >= 20.35 mN m-1). These findings illustrate the potential of amphiphilic copolymers as a modular, straightforward, and versatile platform for next-generation fluorosurfactants as an alternative to long-chain legacy PFAS.

Prospective memory (PM) refers to the ability to remember to carry out intended actions at a future point in time. Despite extensive research on the cognitive underpinnings of PM, the role of environmental factors, such as parent-child interaction through scaffolding, remains largely unexplored. The present study examined the relations between parental PM performance, parental scaffolding, and 8- to 10-year-old children's PM performance. A total of 42 German parent-child dyads participated in the study and completed the Virtual Week task as a measure of laboratory-based PM. Virtual Week comprises regular (repeating) and irregular (one-off) PM tasks. Further, parents completed questionnaires assessing their scaffolding behavior, their own everyday PM, and their perception of their children's everyday PM, while children provided self-ratings of their everyday PM performance. Parents' performance on regular PM tasks predicted children's laboratory-based PM, but parental metacognition did not. In addition, parents' scaffolding behavior was positively associated with children's performance on regular PM tasks, suggesting that more active scaffolding supports the development of children's everyday prospective remembering. Overall, these findings highlight the importance of social and environmental factors in shaping children's PM development and point to potential avenues for future research and intervention targeting parent-child interactions.