Impact of Graphene Quantum Dot Edge Shapes on High-Performance Energy Storage Devices

Graphene quantum dots (GQDs) are a promising electrode material for the advancement of energy storage devices due to their fast-moving charge carriers, high surface area to volume ratio and controllable bandgaps. However, the differences between the electronic properties of zigzag and armchair-edged graphene quantum dots (GQDs) have not yet been well defined and are explored in detail in this work. Nitrogen-doped GQDs with zigzag (ZZ) and armchair (AC) edges were synthesised hydrothermally and electrochemically, respectively. Surface (XRD, TEM, UV-Vis) characterisation was conducted on the synthesised GQDs. It was found that the bandgap of ZZ GQDs is controllable through pH variation and size variations dictated by synthetic reaction times, while this is not the case for AC GQDs. ZZ and AC GQDs were electrodeposited on the surface of carbon fibre electrodes. Electrochemical characterisation (cyclic voltammetry, electrical impedance spectroscopy) was carried out on these electrodes. The specific capacitance of all carbon fibre electrodes increased upon the deposition of GQDs, with the greatest increase observed to be a 275 % improvement in specific capacitance upon the addition of 5 nm zigzag GQDs. Carbon fibre electrodes with deposited ZZ GQDs display a more significant increase in capacitance values (specific capacitance, electrical double layer capacitance, pseudocapacitance and quantum capacitance) due to a greater affinity for edge site doping and a larger surface area compared to AC GQD carbon fibre electrodes. ZZ GQDs are therefore more beneficial for energy storage devices than AC GQDs

Paddling A Trail

Paddling A Trail documents construction of the first water trail in Arkansas. The 15 minute film is narrated by Arkansas Canoe Club Conservation Chair Debbie Doss. It follows Doss, and other volunteers as they mark the Wattensaw Bayou Trail in Hazen, Arkansas. The film is co-narrated by Kristen Bartlow of the Arkansas Game and Fish Commission. The footage was shot over three days, in two different locations. These were the White River in Northwest Arkansas and Wattensaw Bayou in Hazen, AR. The film illustrates the positive role trails can have on the environment and local economies. More importantly, the film uses Doss’s personal account to show how environmental deterioration and its results often go unnoticed

School socio-economic context and student achievement in Ireland: an unconditional quantile regression analysis using PISA 2018 data

© 2023. The authors. This document is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by /4.0/ This document is the published version of a Published Work that appeared in final form in Large-scale Assessments in Education. To access the final edited and published work see https://doi.org/10.1186/s40536-023-00171-xBackground: The existence of a multiplier, compositional or social context efect is debated extensively in the literature on school efectiveness and also relates to the wider issue of equity in educational outcomes. However, comparatively little attention has been given to whether or not the association between student achievement and school socio-economic composition may vary across the achievement distribution. Furthermore, with limited exception, comparatively little use has been made of unconditional quantile modelling approaches in the education literature. / Methods: This paper uses Irish data from the Programme for International Student Assessment 2018 and employs ordinary least squares regression and unconditional quantile regression empirical approaches to examine the association between school socio-economic composition and achievement. Reading and mathematics achievement are used as outcome variables and models control for a rich set of school and student characteristics. / Results: Findings from the ordinary least squares regression show that, on average, there is a signifcant negative relationship between school socio-economic disadvantage and student achievement in reading and mathematics having controlled from a range of individual and school-level variables. From a distributional perspective, unconditional quantile regression results show variation in the strength of the relationship between school socio-economic disadvantage and student achievement, particularly in reading, with a stronger association at the lower end of the achievement distribution. Findings illustrate the need to give nuanced consideration to how students with varying levels of achievement may experience a socio-economically disadvantaged context at school. Our fndings also draw attention to the beneft of examining variation in the association between achievement and explanatory variables across the achievement distribution and underscore the importance of moving beyond an exclusive focus on the mean of the distribution. Finally, we emphasise the importance of drawing population-level inferences when using the unconditional quantile regression method