ABSTRACT
The advent of graphene has renewed the interest in other 2D carbon-based materials. In particular, new structures have been proposed by combining hexagonal and other carbon rings in different ways. Recently, Bhattacharya and Jana have proposed a new carbon allotrope, composed of different polygonal carbon rings containing 4, 5, 6, and 10 atoms, named tetra-penta-deca-hexagonal-graphene (TPDH-graphene). This unusual topology results in interesting mechanical, electronic, and optical properties with several potential applications, including UV protection. Like other 2D carbon structures, chemical functionalizations can be used to tune TPDH-graphene's physical/chemical properties. In this work, we investigate the hydrogenation dynamics of TPDH-graphene and its effects on its electronic structure, combining DFT and fully atomistic reactive molecular dynamics simulations. Our results show that H atoms are mainly incorporated on tetragonal ring sites (up to 80% at 300 K), leading to the appearance of well-delimited pentagonal carbon stripes. The electronic structure of the hydrogenated structures shows the formation of narrow bandgaps with the presence of Dirac cone-like structures, indicative of anisotropic transport properties.
ABSTRACT
OBJECTIVE: To investigate the frequency and perform a qualitative analysis of spin bias in publications of controlled trials assessing the therapeutic use of cannabis derivatives and their synthetic analogues. STUDY DESIGN AND SETTING: Meta-epidemiologic study carried out at the Universidade Federal de São Paulo, Brazil. RESULTS: A total of 65 publications with at least one efficacy primary outcome were considered. The results analysis for the primary outcome indicated statistically significant effects in 44.6% (29/65) of the publications, and 70.7% (45/65) of the conclusions were considered favorable to the intervention. Among the 36 publications that found statistically nonsignificant results for the primary outcome, 44.4% (16/36) presented conclusions favorable to or recommending the intervention, which represents spin bias according to the definition adopted in this study. Qualitative analysis of the 16 studies with spin bias showed selective outcomes reporting (elevating secondary outcomes that had positive results or reporting only subgroup results), deviations from the planned statistical analysis, and failure to consider or report uncertainty in the estimates of treatment effects. CONCLUSION: The frequency of spin bias among publications of controlled trials with statistically nonsignificant results assessing the therapeutic use of cannabis derivatives and their synthetic analogues reached 44.4%. When not observed by readers, such deviation can lead to misconduct in clinical practice through the adoption of interventions that are not effective or whose effectiveness is uncertain.