Numerical Investigations of Shape Memory Alloy Fatigue

This work deals with numerical investigations of the functional and structural fatigue on shape memory alloys (SMAs). A thermodynamically consistent, three-dimensional constitutive model is employed, adopting a continuum damage perspective. Fatigue life is predicted by considering a macroscopic model. Numerical simulations are compared with experimental data taken from the literature to demonstrate the model’s ability to capture the general thermomechanical behavior of SMAs subjected to different loading conditions. Uniaxial and torsion tests are discussed; thermal loads are also analyzed considering the influence of the maximum temperature on the fatigue life of SMAs. Cyclic degradation of the shape memory effect is investigated in the sequence. Results show that numerical simulations are in good agreement with the experimental data, including the fatigue life estimation.

Degradation mechanism of hybrid tin-based perovskite solar cells and the critical role of tin (IV) iodide

Tin perovskites have emerged as promising alternatives to toxic lead perovskites in next-generation photovoltaics, but their poor environmental stability remains an obstacle towards more competitive performances. Therefore, a full understanding of their decomposition processes is needed to address these stability issues. Herein, we elucidate the degradation mechanism of 2D/3D tin perovskite films based on (PEA)0.2(FA)0.8SnI3 (where PEA is phenylethylammonium and FA is formamidinium). We show that SnI4, a product of the oxygen-induced degradation of tin perovskite, quickly evolves into iodine via the combined action of moisture and oxygen. We identify iodine as a highly aggressive species that can further oxidise the perovskite to more SnI4, establishing a cyclic degradation mechanism. Perovskite stability is then observed to strongly depend on the hole transport layer chosen as the substrate, which is exploited to tackle film degradation. These key insights will enable the future design and optimisation of stable tin-based perovskite optoelectronics.

A Composite Material of Hydrothermal Prepared Blue Fescue-Like CQDs/Sn-Doped ZnO with Enhanced Visible Light-Driven Photocatalytic Activity

Novel Blue Fescue-like CQDs/Sn-doped ZnO composite photocatalyst was successfully synthesized via a gentle hydrothermal method. The hierarchical CQD/Sn-doped ZnO samples are assembled by many hexagonal prism-shaped nanoneedles. In addition, the photocatalytic performance of all samples was obtained by degrading rhodamine B(RhB) under visible light irradiation. The degradation results indicate that the photocatalytic activity of CQDs/Sn-doped ZnO is better than Sn-doped ZnO, CQDs/ZnO, pure CQDs and pure ZnO. The stability and reusability of CQDs/Sn-doped ZnO were confirmed by cyclic degradation experiments. It can be considered that the effective photocatalytic performance is attributed to the adsorption and transfer of electrons by CQDs.

Cycling in degradation of organic polymers and uptake of nutrients by a litter-degrading fungus

SummaryWood and litter degrading fungi are the main decomposers of lignocellulose and thus play a key role in carbon cycling in nature. Here we provide evidence for a novel lignocellulose degradation strategy employed by the litter degrading fungus Agaricus bisporus (known as the white button mushroom). Fusion of hyphae allows this fungus to synchronize the activity of its mycelium over large distances (50 cm). The synchronized activity has an 13-hour interval that increases to 20 h before becoming irregular and is associated with a 3.5-fold increase in respiration while compost temperature increases up to 2 °C. Transcriptomic analysis of this burst-like phenomenon supports a cyclic degradation of lignin, deconstruction of (hemi-) cellulose and microbial cell wall polymers, and uptake of degradation products during vegetative growth of A. bisporus. Cycling in expression of the ligninolytic system, enzymes involved in saccharification, and nutrient uptake is proposed to provide an efficient way for degradation of substrates such as litter.