A simple and scalable electrospinning process followed by thermal treatment was used to fabricate carbon nanofibers (CFs). The asprepared CFs were investigated as anode materials for sodium ion batteries (SIBs). Remarkably, due to their weakly ordered turbostratic structure and a large interlayer spacing between graphene sheets, the CFs exhibit a dominant adsorption/insertion sodium storage mechanism that shows high reversibility. As a result, the CFs show excellent electrochemical performance, especially cycle stability (97.7% capacity retention ratio over 200 cycles). Reversible capacities of 233 and 82 mA h g À1 are obtained for the CFs at a current density of 0.05 A g À1 and even a high current density of 2 A g À1 , respectively. The excellent cycle performance, high capacity and good rate capability make the CFs promising candidates for practical SIBs.

This experiment was conducted to evaluate the effects of protein levels on the growth performance, digestive capacity and amino acid metabolism of juvenile Jian carp. Brown fish meal was used as the sole protein source in the present study. Six isoenergetic experimental diets containing 14.4 MJ kg−1 of digestible energy and 220–495 g crude protein kg−1 diets were fed to triplicate groups of 50 fish with a mean initial weight of 16.67 ± 0.01 g for 45 days. Per cent weight gain (PWG) and feed efficiency ratio (FER) improved with an increase in the dietary protein levels up to 330 g kg−1 diet. The condition factor, relative gut length, intestinal folds height, hepatopancreas and intestine protein content improved with an increase in the protein levels up to 330–385 g kg−1 diet. Trypsin, creatinkinase, Na+, K+‐ATPase and alkaline phosphatase activities generally followed the same tendency as that of growth parameters. Amylase and γ‐glutamyl transpeptidase (γ‐GT) activities were negatively correlated with increasing protein levels from 220 to 330 g kg−1 diet, and no differences were found thereafter. Lipase activity was unaffected by protein levels. Lactobacillus amount was increased with protein levels up to 275 g kg−1 diet, while Aeromonas amount followed the opposite pattern. Escherichia coli amount was not influenced by dietary protein levels. Glutamate–oxaloacetate transaminase (GOT) activities in the hepatopancreas and plasma ammonia concentration (PAC) were not influenced by protein levels between 220 and 275 g kg−1 diet, but significantly increased with increasing protein levels from 275 to 440 g kg−1 diet, and remained similar thereafter. Glutamate–pyruvate transaminase (GPT) activities significantly increased with protein levels >275 g kg−1 diet. Based on the broken‐line model, the dietary protein requirement for PWG of Jian carp (16.7–55.0 g) was estimated to be 341 g kg−1 diet with a digestible energy of 14.4 MJ kg−1 diet.

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