Sb2O3 nanoparticles anchored on N-doped graphene nanoribbons as improved anode for sodium-ion batteries.

Sodium-ion batteries (SIBs) are emerging as a promising alternative to conventional lithium-ion technology, due to the abundance of sodium resources. Still, major drawbacks for the commercial application of SIBs lie in the slow kinetic processes and poor cycling performance of the devices. In this work, a hybrid nanocomposite of Sb2O3 nanoparticles anchored on N-doped graphene nanoribbons (GNR) is implemented as anode material in SIBs. The obtained Sb2O3/N-GNR anode delivers a reversible specific capacity of 642 mA h g-1 after 100 cycles at 0.1 A g-1 and exhibits a good rate capability. Even after 500 cycles at 5 A g-1, the specific capacity is maintained at about 405 mA h g-1. Such good Na storage performance is mainly ascribed to the beneficial effect of N doping for charge transfer and to the improved microstructure that facilitates the Na+ diffusion through the overall electrode.

Microbiome differences between river-dwelling and cave-adapted populations of the fish Astyanax mexicanus (De Filippi, 1853).

Symbiotic relationships between host and microbiome can play a major role in local adaptation. Previous studies with freshwater organisms have shown that microbiome performs numerous important biochemical functions for the host, playing a key role in metabolism, physiology or health. Experimental studies in fish groups have found an effect of enzymatic activity of gut microbiota on a variety of metabolic processes. The goal of this study was to compare stomach microbiome from cave and surface Astyanax mexicanus, in order to evaluate the potential response of microbiota to contrasting environmental conditions and physiological adaptations of the host. Stomach microbiota was obtained from three different populations: Pachón cave, and two surface rivers (Rascón and Micos rivers). The stomach microbiome was analyzed using the Ion 16S Metagenomic kit considering seven variable regions: V2, V3, V4, V6-7, V8 and V9. A high diversity was observed across samples, including 16 phyla, 120 families and 178 genera. Gammaproteobacteria, Firmicutes, Bacteroidetes and Betaproteobacteria were the most abundant phyla across the samples. Although the relative abundance of the core OTUs at genus level were highly contrasting among populations, we did not recover differences in stomach microbiome between contrasting habitats (cave vs. surface rivers). Rather, we observed a consistent association between ß-diversity and dissolved oxygen concentration in water. Therefore, and unexpectedly, the microbiota of A. mexicanus is not linked with the contrasting conditions of the habitat considered here but is related to water parameters.