Direct Evidence of the Exfoliation Efficiency and Graphene Dispersibility of Green Solvents toward Sustainable Graphene Production.

Achieving a sustainable production of pristine high-quality graphene and other layered materials at a low cost is one of the bottlenecks that needs to be overcome for reaching 2D material applications at a large scale. Liquid phase exfoliation in conjunction with N-methyl-2-pyrrolidone (NMP) is recognized as the most efficient method for both the exfoliation and dispersion of graphene. Unfortunately, NMP is neither sustainable nor suitable for up-scaling production due to its adverse impact on the environment. Here, we show the real potential of green solvents by revealing the independent contributions of their exfoliation efficiency and graphene dispersibility to the graphene yield. By experimentally separating these two factors, we demonstrate that the exfoliation efficiency of a given solvent is independent of its dispersibility. Our studies revealed that isopropanol can be used to exfoliate graphite as efficiently as NMP. Our finding is corroborated by the matching ratio between the polar and dispersive energies of graphite and that of the solvent surface tension. This direct evidence of exfoliation efficiency and dispersibility of solvents paves the way to developing a deeper understanding of the real potential of sustainable graphene manufacturing at a large scale.

National survey to identify subspecialties at risk for physician shortages in Canadian academic radiology departments.

PURPOSE: To identify subspecialty fields in Canadian academic radiology departments that are at risk for future manpower shortages. To determine reasons for the potential shortages and suggest potential solutions. METHODS: An anonymous online survey was sent by e-mail to radiology residents and academic radiology department heads in Canada. The survey was open from April 1 to August 1, 2006. Statistical analysis by using the SAS Frequency Procedure was performed on the results. RESULTS: Interventional radiology, neuroradiology, mammography, cardiac imaging, and pediatric radiology were identified as areas in which there will be increasing workforce demands. Mammography, pediatric radiology, and cardiac imaging were identified as areas in which there will be a potential decrease in supply. Of the residents, 65.83% intended on pursuing subspecialty training. Priorities were interesting work, job availability, and work schedule. Nuclear medicine, mammography, pediatric radiology, and interventional radiology were identified as the top 4 areas in which residents specifically did not want to pursue further subspecialty training. Only 15% of resident respondents received career counseling during residency, and only 50% of those residents thought it was adequate. CONCLUSIONS: Our survey results indicate that mammography, cardiac imaging, and pediatric radiology are at risk for manpower shortages, and interventional radiology may be at risk. Increased efforts to recruit trainees may be necessary to ensure that these subspecialties maintain their presence in the future. Only 15% of the surveyed residents received career counseling during residency. This is a relatively untapped forum that academic staff could use to help recruit new trainees into these underserved subspecialties.