Fatigue and damage tolerance behaviour of corroded 2024 T351 aircraft aluminum alloy

The fatigue and damage tolerance behaviour of pre-corroded 2024 T351 aluminum alloy specimens has been investigated and compared to the behaviour of the uncorroded material. The experimental investigation was performed on specimens pre-corroded in exfoliation corrosion environment and included the derivation of S–N and fatigue crack growth curves as well as measurements of fracture toughness. The fatigue crack growth tests were performed for different stress ratios R. To obtain reference material behaviour all mechanical tests were repeated under the same conditions for uncorroded specimens. For the corroded material an appreciable decrease in fatigue resistance and damage tolerance was obtained. The results of the experimental investigation were discussed under the viewpoint of corrosion and corrosion-induced hydrogen embrittlement of the 2024 aluminum alloy. The need to account for the influence of pre-existing corrosion on the material’s properties in fatigue and damage tolerance analyses of components involving corroded areas was demonstrated.     

Photocatalytic Formic Acid Conversion on CdS Nanocrystals with Controllable Selectivity for H2 or CO

Formic acid is considered a promising energy carrier and hydrogen storage material for a carbon‐neutral economy. We present an inexpensive system for the selective room‐temperature photocatalytic conversion of formic acid into either hydrogen or carbon monoxide. Under visible‐light irradiation (λ>420 nm, 1 sun), suspensions of ligand‐capped cadmium sulfide nanocrystals in formic acid/sodium formate release up to 116±14 mmol H₂ g_cat^?1 h^?1 with >99 % selectivity when combined with a cobalt co‐catalyst; the quantum yield at λ=460 nm was 21.2±2.7 %. In the absence of capping ligands, suspensions of the same photocatalyst in aqueous sodium formate generate up to 102±13 mmol CO g_cat^?1 h^?1 with >95 % selectivity and 19.7±2.7 % quantum yield. H₂ and CO production was sustained for more than one week with turnover numbers greater than 6×10⁵ and 3×10⁶, respectively.     

Polymer Capsules as a Theranostic Tool for a Universal In Vitro Screening Assay—The Case of Lysosomal Storage Diseases

Lysosomal storage disorders are rare genetic diseases characterized by a lysosomal enzyme deficiency. The defect leads to an accumulation of normally degraded substrates within the lysosomes. The accumulation of polymeric capsules inside the lysosomes is exploited to create a universal in vitro theranostic tool for lysosomal storage disorders. The diagnostic ability of this tool based on pH‐sensitive fluorophores is demonstrated by monitoring the lysosomal pH in Krabbe‐disease cell models upon accumulation of the substrate psychosine. Krabbe‐affected cells maintain their normal pH, while the lysosomes of their healthy counterparts undergo alkalinization, which can be correlated to toxicity. The potential of this tool for therapy based on enzymes inside the capsules is evaluated within the context of enzyme replacement therapy. Enzymatic degradation of the capsules inside the lysosome leads to release of the encapsulated active enzyme and the prevention of adverse effects of accumulated psychosine upon capsule‐based delivery of the functional enzyme is confirmed. In Fabry‐affected cells the intracellular enzymatic activity of the drug Replagal released from capsules shows the same kinetics as the free enzyme, which constitutes the current therapy, although the activity is smaller. Encapsulating Replagal nevertheless represents an alternative to receptor‐mediated endocytosis, overcoming limitations such as low or absent receptor expression.     

On different notions of tameness in arithmetic geometry

The notion of a tamely ramified covering is canonical only for curves. Several notions of tameness for coverings of higher dimensional schemes have been used in the literature. We show that all these definitions are essentially equivalent. Furthermore, we prove finiteness theorems for the tame fundamental groups of arithmetic schemes.     

Über die Cumarine der Droge Semen Angelicae

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