Preparation of Fluorescent Carbon-Based Dots from Waste Tire Pyrolysis
JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
Authors: Parra, Juliana B.; Silva, Karina C.; Valezin, Pedro A. S.; Martins, Raphael G.; Gomes, Rodolfo R.; Pereira, Rafael S.; de Melo, Fernando M.; Morandim-Giannetti, Andreia de A.; dos Santos, Ronaldo G.; Panzarini, Luz Consuelo G. A.; Toyama, Marcos M.
Abstract
The pyrolysis of waste tire has been proposed as an alternative route to its recycling producing residual oils that can be used as fuels. In this work, a physicochemical process to obtain carbon-based dots (CBD) from carbon black (CBL) derivatives of tires is described. For this, the CBL was treated with different acids to produce CBL1 and CBL2 particles suspension. The pH of the suspension was adjusted to 5.6 to precipitate remaining impurities. Afterwards, the supernatant was ultra-centrifuged and the yellow pale solid, the purified CBD obtained by roto evaporation, was characterized by ultraviolet-visible spectrophotometer (UV-Vis), photoluminescence (PL) at 320-380 nm, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared microscopy (mu FTIR), and X-ray photoelectron spectroscopy (XPS). This material showed the typical excitation wavelength dependent emission and a PL quantum yield of 19.29% and was constituted by a well-defined spherical shaped and single sheets of "graphene quantum dots" with undefined shape, with potential applications in optoelectronic and fluorescence imaging devices.
Effects of peer-led debriefing using simulation with case-based learning: Written vs. observed debriefing
NURSE EDUCATION TODAY
Authors: Ha, Eun-Ho
Abstract
Background: Peer-led written debriefing (PLWD) and peer-led observed debriefing (PLOD) are types of peer-led debriefing. Despite their advantages, these methods are sparingly used among debriefing experts. Objective: To identify effects of peer-led debriefing (written versus observed) using simulation with case-based learning (CBL) and compare levels of satisfaction with CBL, debriefing, and simulation-based learning (SBL) between the two groups. Design: Quasi-experimental study used a pretest-posttest non-equivalent control group. Setting: Department of Nursing in C province, South Korea. Participants: Sixty-nine third-year undergraduate nursing students (PLWD, n = 33; PLOD, n = 36). Methods: Differences in clinical performance competency, and satisfaction of CBL, SBL, and debriefing between the PLWD and PLOD groups were determined. Results: Clinical performance competency scores of posttest in both the PLWD and PLOD groups were significantly higher than those of pretest. There were no significant differences in any item except for item of 'communication' (t = -2.150, p = .047) between the PLWD and PLOD groups. There were no significant differences in satisfaction with CBL (t = -0.874, p = .385), simulation (t = -0.701, p = .485), or debriefing (t = -1.024, p = .309) between the two groups. Conclusion: This study suggests that both the PLWD and PLOD could be used to achieve students' learning outcomes when debriefing experts are unavailable.