Jill Guo

This paper, co-authored by undergraduate students and their instructor part of an educational psychology seminar, describes a participatory curriculum design approach for preservice teacher education that focuses on the use of the principles of second-order cybernetics to teach about teaching and learning. Using elements of an Open Source Educational Processes framework, our Spring ESEPSY2309 section created project-based collective hive minds of preservice teachers, relying on a cybernetic approach at the crossroads of Gregory Bateson and Gordon Pask's theories. The classroom community used four innovative tool-mediated pillars to guide collaborative activity: 1) Live-chatting using the Reddit social media platform, 2) observation of the lives, strategies, and practices used by teachers and students in their own social networks through Soundcloud podcasting to expand their own perceptions of pedagogies and best practices that they could employ in their careers, 3) open-ended paper writing, exploring sources beyond the object language provided by the textbook through extensive dyadic conversations with the instructor, and 4) training in the use of the Alice 3 game creation tool for block programming enabling the accumulation of competence in designing classroom systems that may treat students these undergraduates would soon teach as active historical agents in learning environments, combining skills from varied subjects into transdisciplinary educational experiences. We showcase outcomes of our class projects using a narrative inquiry to describe podcast episodes, a topic network analysis to illustrate the expansive nature of Open Source writing activity, and a visual depiction of our class Alice 3 games.

© 2016, Nature Publishing Group. All rights reserved.Interest in hydrogen fuel is growing for automotive applications; however, safe, dense, solid-state hydrogen storage remains a formidable scientific challenge. Metal hydrides offer ample storage capacity and do not require cryogens or exceedingly high pressures for operation. However, hydrides have largely been abandoned because of oxidative instability and sluggish kinetics. We report a new, environmentally stable hydrogen storage material constructed of Mg nanocrystals encapsulated by atomically thin and gas-selective reduced graphene oxide sheets. This material, protected from oxygen and moisture by the rGO layers, exhibits exceptionally dense hydrogen storage. As rGO is atomically thin, this approach minimizes inactive mass in the composite, while also providing a kinetic enhancement to hydrogen sorption performance. These multilaminates of rGO-Mg are able to deliver exceptionally dense hydrogen storage and provide a material platform for harnessing the attributes of sensitive nanomaterials in demanding environments.

Lithium/sulfur cells have attracted much attention due to their higher theoretical specific capacity and energy compared to those of current lithium-ion cells. However, the application of Li/S cells is still hampered by short cycle life. Sulfur-graphene oxide nanocomposites have shown promise as cathode materials for long-life Li/S cells because oxygen-containing functional groups on the surface of graphene oxide were successfully used as sulfur immobilizers by forming weak bonds with sulfur and polysulfides. While S-GO showed much improved cycling performance, the capacity decay still needs to be improved for commercially viable cells. In this study, we attempt to understand the capacity fading mechanism based on an ex situ study of the structural and chemical evolution of S-GO nanocomposite cathodes with various numbers of cycles using scanning electron microscopy, near edge X-ray absorption fine structure and X-ray photoelectron spectroscopy. It is found that both the surface morphologies and chemical structures of the cathode materials change considerably with increasing number of cycles. These changes are attributed to several unexpected chemical reactions of lithium with S-GO nanocomposites occurring during the discharge-charge processes with the formation of Li2CO3, Li2SO3, Li 2SO4, and COSO2Li species. These reactions result in the loss of recyclable active sulfur on the surface of the electrode, and thus capacity fades while coulombic efficiency is near 100%. Moreover, the reaction products accumulate on the cathode surface, forming a compact blocking insulating layer which may make the diffusion of Li ions into/out of the cathode difficult during the discharge-charge process and thus lead to lower utilization of sulfur at higher rates. We think that these two observations are significant contributors to the capacity and rate capability degradation of the Li/S-GO cells. Therefore, for the rechargeable Li/S-GO cells, we suggest that the content of oxygen-containing functional groups on GO should be optimized and more stable functional groups need to be identified for further improvement of the cycling performance. The information we gain from this study may provide general insights into the fundamental understanding of the degradation mechanisms of other rechargeable Li/S cells using similar oxygen-containing functional groups as sulfur immobilizers. © the Partner Organisations 2014.