Abstract:In order to progress from the lab to commercial applications it will be necessary to develop industrially scalable methods to produce large quantities of defect-free graphene.Here we show that high-shear mixing of graphite in suitable, stabilizing liquids results in large-scale exfoliation to give dispersions of graphene nanosheets. XPS and Raman spectroscopy show the exfoliated flakes to be unoxidised and free of basal plane defects. We have developed a simple model which shows exfoliation to occur once the local shear rate exceeds 10 4 s -1 . By fully characterizing the scaling behaviour of the graphene production rate, we show that exfoliation can be achieved in liquid volumes from 100s of ml up to 100s of litres and beyond. The graphene produced by this method performs well in applications from composites to conductive coatings. This method can be applied to exfoliate BN, MoS2 and a range of other layered crystals. Main Text:Due to its ultra-thin, 2-dimensional nature and its unprecedented combination of physical properties, graphene has become the most studied of all nano-materials. In the next decade graphene is likely to find commercial applications in many areas from high-frequency electronics to smart coatings.

Multiple knowledges are available for utilisation in policy choice. The rank ordering of knowledges for use in decisionmaking is thus a fundamental predecision. This article shows how this predecision necessarily constrains the processes associated with a politics of ideas, using cases from American international commodity policy. Even when the supposed preconditions of this sort of politics are present, policy change did not occur when the proposed ideas arose from a knowledge accorded secondary status in policymaking circles. Several implications are discussed for the influence and the study of ideational politics. Ultimately, the politics of ideas, so often portrayed through cases of innovation, may be quite conservative, contained by knowledge hierarchies which reflect prior politicaxl circumstances.

Abstract:The covalent chemical functionalization of exfoliated hexagonal boron-nitride nanosheets (BNNSs) is achieved by the solution phase oxygen radical functionalization of boron atoms in the h-BN lattice. This involves a two-step procedure to initially covalently graft alkoxy groups to boron atoms and the subsequent hydrolytic defunctionalisation of the groups to yield hydroxyl-functionalized BNNSs (OHBNNSs). Characterization of the functionalized-BNNSs using HR-TEM, Raman, UV-Vis, FTIR, NMR, and TGA was performed to investigate both the structure of the BNNSs and the covalent functionalization methodology. OH-BNNSs were used to prepare polymer nanocomposites and their mechanical properties analyzed. The influence of the functional groups grafted to the surface of the BNNSs is investigated by demonstrating the impact on mechanical properties of both non-covalent and covalent bonding at the interface between the nanofiller and polymer matrices.

This article addresses the influence of politicians, managers, and the dispositions of streetlevel bureaucrats in shaping actions at the frontlines of policy implementation. We investigate these for the implementation of employment policy reforms in Denmark. Our findings show a large percentage of caseworkers emphasizing actions that are consistent with the national employment reform goal of getting clients into jobs quickly. The influence of politicians and managers in bringing this about is relatively limited in comparison to the influences of caseworkers' understanding of policy goals, their professional knowledge, and their policy predispositions. Our main contribution is an unpacking of the political and managerial influences on caseworkers' policy emphases. We find direct effects and, more notably, indirect effects that operate on the influence of caseworkers' perceptions of policy goals and their knowledge. These findings provide a more nuanced and positive assessment than much of the implementation literature of the way that higher level policies are translated into actions at the frontlines. Mette H. Skou and Mette Fjord Sørensen provided substantial research assistance in preparing this article.

We describe three related methods to disperse graphene in solvents with concentrations from 2 to 63 mg/mL. Simply sonicating graphite in N-methyl-2-pyrrolidinone, followed by centrifugation, gives dispersed graphene at concentrations of up to 2 mg/mL. Filtration of a sonicated but uncentrifuged dispersion gives a partially exfoliated powder that can be redispersed at concentrations of up to 20 mg/mL. However, this process can be significantly improved by removing any unexfolaited graphite from the starting dispersion by centrifugation. The centrifuged dispersion can be filtered to give a powder of exfoliated few-layer graphene. This powder can be redispersed at concentrations of at least 63 mg/mL. The dispersed flakes are ~1 μm long and ~3 to 4 layers thick on average. Although some sedimentation occurs, ~26-28 mg/mL of the dispersed graphene appears to be indefinitely stable.