Combined Effects of Fluoride and Dietary Seleno-L-Methionine at Environmentally Relevant Concentrations on Female Zebrafish (Danio rerio) Liver: Histopathological Damages, Oxidative Stress and Inflammation.

Fluoride, a global environmental pollutant, is ubiquitous in aquatic environments and coexists with selenium, which can cause complex effects on exposed organisms. However, data on the interaction of fluoride and selenium remain scarce. In this study, female zebrafish (Danio rerio) were exposed to fluoride (80 mg/L sodium fluoride) and/or dietary selenomethionine (Se-Met) for 30, 60 and 90 days, the effects on the liver of zebrafish were investigated. The results indicated that an increase in fluoride burden, inhibited growth and impaired liver morphology were recorded after fluoride exposure. Furthermore, fluoride alone caused oxidative stress and inflammation in the liver, as reflected by the increase in ROS and MDA contents, the reduction of anti-oxidative enzymes, the altered immune related enzymes (ACP, AKP, LZM and MPO) and the expression of IL-6, IL-1ß, TNF-α, IL-10 and TGF-ß. In contrast, co-exposure to fluoride and Se-Met decreased fluoride burden and restored growth. Furthermore, dietary Se-Met alleviated oxidative stress, inflammation and impaired morphology in liver trigger by fluoride. However, dietary Se-Met alone increased the activities of SOD and CAT. These results demonstrate that the protective effect of dietary Se-Met against chronic fluoride toxicity at a certain level.

One-Dimensional Frenkel Chain Defects in CsBi4Te6.

Understanding the detailed process of spontaneous formation of intrinsic defects and their ability to tune the electronic structures in functional materials has become a key prerequisite for their technological applications. Here, by using in situ scanning tunneling microscopy, we report the observation of one-dimensional Frenkel chain defects on the cleaved CsBi4Te6 surface due to the migration of Te atoms for the first time. Further scanning tunneling spectroscopy measurements clearly revealed a self-electron doping effect of the Frenkel chain defects, which could directly affect their thermoelectric and superconducting properties. The unique one-dimensional Frenkel tellurium atomic chain defect and its doping effect on the electronic structure observed here not only shed light on tuning the electric properties of a series of tellurides but also possess profound implications for enriching the microscopic details of defect chemistry and materials science.

Large-area, periodic, and tunable intrinsic pseudo-magnetic fields in low-angle twisted bilayer graphene.

A properly strained graphene monolayer or bilayer is expected to harbour periodic pseudo-magnetic fields with high symmetry, yet to date, a convincing demonstration of such pseudo-magnetic fields has been lacking, especially for bilayer graphene. Here, we report a definitive experimental proof for the existence of large-area, periodic pseudo-magnetic fields, as manifested by vortex lattices in commensurability with the moiré patterns of low-angle twisted bilayer graphene. The pseudo-magnetic fields are strong enough to confine the massive Dirac electrons into circularly localized pseudo-Landau levels, as observed by scanning tunneling microscopy/spectroscopy, and also corroborated by tight-binding calculations. We further demonstrate that the geometry, amplitude, and periodicity of the pseudo-magnetic fields can be fine-tuned by both the rotation angle and heterostrain. Collectively, the present study substantially enriches twisted bilayer graphene as a powerful enabling platform for exploration of new and exotic physical phenomena, including quantum valley Hall effects and quantum anomalous Hall effects.