Selective Area Band Engineering of Graphene using Cobalt-Mediated Oxidation

This study reports a scalable and economical method to open a band gap in single layer graphene by deposition of cobalt metal on its surface using physical vapor deposition in high vacuum. At low cobalt thickness, clusters form at impurity sites on the graphene without etching or damaging the graphene. When exposed to oxygen at room temperature, oxygen functional groups form in proportion to the cobalt thickness that modify the graphene band structure. Cobalt/Graphene resulting from this treatment can support a band gap of 0.30 eV, while remaining largely undamaged to preserve its structural and electrical properties. A mechanism of cobalt-mediated band opening is proposed as a two-step process starting with charge transfer from metal to graphene, followed by formation of oxides where cobalt has been deposited. Contributions from the formation of both CoO and oxygen functional groups on graphene affect the electronic structure to open a band gap. This study demonstrates that cobalt-mediated oxidation is a viable method to introduce a band gap into graphene at room temperature that could be applicable in electronics applications

Chaos, danger, and maternal parenting in families: Links with adolescent adjustment in low- and middle-income countries.

The current longitudinal study is the first comparative investigation across low‐ and middle‐income countries (LMICs) to test the hypothesis that harsher and less affectionate maternal parenting (child age 14 years, on average) statistically mediates the prediction from prior household chaos and neighborhood danger (at 13 years) to subsequent adolescent maladjustment (externalizing, internalizing, and school performance problems at 15 years). The sample included 511 urban families in six LMICs: China, Colombia, Jordan, Kenya, the Philippines, and Thailand. Multigroup structural equation modeling showed consistent associations between chaos, danger, affectionate and harsh parenting, and adolescent adjustment problems. There was some support for the hypothesis, with nearly all countries showing a modest indirect effect of maternal hostility (but not affection) for adolescent externalizing, internalizing, and scholastic problems. Results provide further evidence that chaotic home and dangerous neighborhood environments increase risk for adolescent maladjustment in LMIC contexts, via harsher maternal parenting