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Small villages and their sanitary infrastructure—an unnoticed influence on water quantity and a threat to water quality in headwater catchments
(2023-11-16)
In rural catchments, villages often feature their own, separate urban water infrastructure, including combined sewer overflows (CSOs) or wastewater treatment plants (WWTPs). These point sources affect the water quantity and quality of the receiving low order streams. However, the extent of this impact is rarely monitored. We installed discharge and water quality measurements at the outlet of two small, neighbouring headwater catchments, one that includes a village, a WWTP, and two CSOs, while the other is predominantly ...
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Transformation and Leaching Simulation of 6:2 and 8:2 diPAP and Related Metabolites in Unsaturated Soil Column Studies with MACRO
(2023-10-14)
PFAS (perfluoroalkyl substances) are widespread in the environment and are found in almost every medium. Besides persistent PFAS, their transforming precursors gained attention since they may be a reservoir for persistent PFAS in soil. Only little information is available about the behavior of these precursors and the simultaneous leaching of their transformation products. However, this information is urgently needed to improve estimates of contamination levels. For this purpose, two precursors and their non-degradable ...
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Controlled Ring Opening of a Tetracyclic Tetraphosphane with Twofold Metallocene Bridging
(2024-02-19)
A direct route to a doubly ferrocene bridged tetracyclic tetraphosphane 1 was developed via reductive coupling of Fe(CpPCl₂)₂ (2 a), where a chlorine terminated linear P₄-compound 3 could be identified as an intermediate. Selective P−P bond activation was further achieved by reacting 1 with elemental selenium or [Cp*Al]₄, where regioselective insertion of Se or Al atoms resulted in ferrocenylene bridged [P₄Se] (4) or [P₄Al] (7) moieties. Compound 7 can be transformed to a hydrogen terminated linear P₄ species, 8, ...
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Fluorescence microscopic investigation of PCE superplasticiser adsorption in calcined clay blended cement
(2024-03-31)
Global efforts to minimise carbon dioxide emissions are also leading to attempts to use calcined clays (CC) as a partial substitute for cement in concrete. While the hydration mechanism of such CC blended cements is now well understood, the range of effective admixtures like polycarboxylate ethers (PCE) is limited. There are PCE types that promise relatively high effectiveness, but the mechanisms of action are not yet sufficiently understood. For a detailed understanding of the adsorption of such PCEs, spatially ...
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Chitosan hydrogels enriched with bioactive phloroglucinol for controlled drug diffusion and potential wound healing
(2024-04)
We report a facile strategy to prepare chitosan (CS) hydrogels that eliminates the need for chemical crosslinking for advanced biomedical therapies. This approach gives controlled properties to the hydrogels by incorporating a natural bioactive phenolic compound, phloroglucinol (PG), into their microstructure. The adsorption of PG onto CS chains enhanced the hydrogels' antioxidant activity by up to 25 % and resulted in a denser, more entangled structure, reducing the pore size by 59 μm while maintaining porosity above ...
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Phospholanes via Twofold C-H-Addition to Phospholes
(2024-05-23)
A synthetic route towards phospholanes via twofold C−H-addition of a DMSO molecule to β-H substituted phospholes is described. The resulting fused phospholane oxothiolane system in case of symmetric α-substitution possesses four stereogenic centers or rather six in case of asymmetric α-substitution. The reaction conditions are shown to be applicable for a variety of phospholes with different P- or α-substituents always leading to stereoselective formation of the fused heterocyclic ring system. All phospholane derivatives ...
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Optimal photoelectron circular dichroism of a model chiral system
(2024-06-03)
We optimize the internuclear geometry and electronic structure of a model chiral system to achieve a maximal photoelectron circular dichroism (PECD) in its one-photon ionization by circularly polarized light. The electronic structure calculations are performed by the single center method, while the optimization is done using quantum alchemy employing a Taylor series expansion. Thereby, the effect of bond lengths and uncompensated charge distributions on the chiral response of the model is investigated theoretically ...
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At the limits of bisphosphonio-substituted stannylenes
(2023-12-13)
Donor stabilization of Sn(II) and Pb(II) halides with 1,1’-ferrocenylene bridged bisphosphanes has been explored for Fe(C₅H₄P(C6H₅)₂)₂ (dppf), and Fe(C₅H₄PH(C₄H9))₂. These bisphosphanes are reacted with SnBr₂ and PbCl₂ with and without additional Lewis acid (AlCl₃) forming acyclic and cyclic donor adducts from which the latter represent bisphosphoniotetrylenes. Since dynamic exchange in solution is observed, characterization includes solution and solid-state NMR in addition to SC-XRD, amended by DFT calculations.
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Yeast gene KTI13 (alias DPH8) operates in the initiation step of diphthamide synthesis on elongation factor 2
(2023-08-08)
In yeast, Elongator-dependent tRNA modifications are regulated by the Kti11•Kti13 dimer and hijacked for cell killing by zymocin, a tRNase ribotoxin. Kti11 (alias Dph3) also controls modification of elongation factor 2 (EF2) with diphthamide, the target for lethal ADP-ribosylation by diphtheria toxin (DT). Diphthamide formation on EF2 involves four biosynthetic steps encoded by the DPH1-DPH7 network and an ill-defined KTI13 function. On further examining the latter gene in yeast, we found that kti13Δ null-mutants ...
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Single-wall carbon nanotubes-chitosan nanocomposites: Surface wettability, mechanical and thermal properties
(2021-04-14)
Functionalized single-wall carbon nanotubes (f-SWCN) are dispersed in chitosan films by self-assembly of both components in aqueous media. This carbon form is a promising nanofiller to achieve nanocomposites with refined thermal, mechanical and surface features. In this study, we investigated the influence of functionalized single-wall carbon nanotubes concentration on the resulting properties of the nanocomposites structures. Functionalized single-wall carbon nanotubes are dispersed on a molecular scale in the ...