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Niobium pentoxide (Nb 2 O 5 ) is a promising negative electrode for sodium ion batteries (SIBs). By engineering the morphology and crystallinity of nanochanneled niobium oxides (NCNOs), the kinetic behavior and charge storage mechanism of Nb 2 O 5 electrodes were investigated. Amorphous and crystalline NCNO samples were made by modulating anodization conditions (20-40 V and 140-180 °C) to synthesize nanostructures of varying pore sizes and wall thicknesses with identical chemical composition. The electrochemical energy storage properties of the NCNOs were studied, with the amorphous samples showing better overall rate performance than the crystalline samples. The enhanced rate performance of the amorphous samples is attributed to the higher capacitive contributions and Na-ion diffusivity analyzed from cyclic voltammetry (CV) and the galvanostatic intermittent titration technique (GITT). It was found that the amorphous samples with smaller wall thicknesses facilitated improved kinetics. Among samples with similar pore size and wall thickness, the difference in their power performance stems from the crystallinity effect, which plays a more significant role in the resulting kinetics of the materials for Na-ion batteries., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The cerebellum, even when not directly damaged, is potentially interesting for understanding the adaptive responses to brain injury. Cerebellar electrocortical activity (ECoG) in rats was studied using spectral and fractal analysis after single and repeated unilateral injury of the parietal cortex. Local field potentials of cerebellar paravermal cortex were recorded before brain injury, in the acute phase (up to 2.5 hours) after a first injury of anesthetized rats, and then before and after second, third, and, in some cases, fourth injury. Relative gamma power (32.1-128.0 Hz) and fractal dimension of ECoGs were temporarily increased after the first injury. However, there was a permanent mild increase in gamma activity and a mild increase in the fractal dimension of cerebellar activity as a chronic change after repeated remote brain injury. There was a negative linear correlation between the normalized difference in fractal dimensions and normalized difference in gamma powers of cerebellar activity only in the case of repeated brain injury. This is the first study showing that correlation between the parameters of spectral and fractal analyses of cerebellar activity can discriminate between single and repeated brain injuries, and is, therefore, a promising approach for identifying specific pathophysiological states.

With application of the Higuchi algorithm, fractal dimension (FD) values of the electrocortical activity of the rat parietal cerebral and paravermal cerebellar cortex were calculated, before and after unilateral discrete injury of the left parietal cortex. Immediately following the first acute injury, in a group of six rats, a reversible increase in mean FD was found at the left (ipsilateral side to the injury) cerebral cortex, from 1.38 to 1.59, and at the left cerebellar cortex from 1.51 to 1.73. In addition, an indication of plastic changes after repeated (third) injury was found as an irreversible increase in mean FD: 1.54 on the left and 1.48 on the right side of parietal cortex.

We investigated cerebellar electrocortical activity before and after unilateral brain injury in anesthetized rats. Spectral analysis of cerebellar activity was obtained by Fast Fourier Transformation. There was a dominance of delta frequency range, while the wide gamma range presented no more than 5% of the total mean power spectra of cerebellar activity before brain injury. A few minutes after brain injury and within the first 90 minutes, there was a decrease of total mean power spectra and a relative decrease of delta range power to about 30%, some increase of beta range, and an increase of gamma range to 20-25%. Relative increase of gamma range in the cerebellar mean power spectra was still present 120 min after the brain injury, while other changes started to diminish. We suggest that spectral changes within slow and fast (gamma) frequency ranges of cerebellar activity may be indicators of the brain state after acute injury.