Abstract
Materials Science![Figure][1] CREDIT: J. T. ROBINSON The properties of bilayer graphene films depend on the relative orientation or twist of the two layers. Robinson et al. grew single-layer graphene on copper surfaces and then performed two transfers of these films onto silica-coated silicon substrates to create bilayer regions. Because these films are polycrystalline, a variety of twist angles between the layers were created across the surface and resulted in a patchwork of colored regions that appeared red, yellow, or blue. Raman spectroscopy was used to characterize the twist angles; the enhancement of the G peak at ∼1600 cm−1 occurred at optical excitation wavelengths that differed for the red and yellow regions, and the extent of enhancement corresponded to the deviation of the orientation of the layers from a distinctive critical twist angle. The twist angles were also confirmed by low-energy electron diffraction studies. The coupling could be minimized by chemical functionalization: fluorination of the top graphene layers with XeF2 quenched the colors, which could be recovered by thermally desorbing the fluorine atoms. ACS Nano 10.1021/nn304834p (2012). [1]: pending:yes
Highlights
The properties of bilayer graphene films depend on the relative orientation or twist of the two layers
Tracing the pathways that lead to neuronal differentiation is important both for understanding neurodevelopment and because of the implications for developing therapeutics for degenerative diseases such as Parkinson’s and Alzheimer’s disease
Recent experiments have demonstrated that a group of transcription factors are capable of converting fibroblasts into neuronal cells in vitro and that the process involves microRNAs
Summary
The properties of bilayer graphene films depend on the relative orientation or twist of the two layers. Robinson et al grew single-layer graphene on copper surfaces and performed two transfers of these films onto silica-coated silicon substrates to create bilayer regions. Because these films are polycrystalline, a variety of twist angles between the layers were created across the surface and resulted in a patchwork of colored regions that appeared red, yellow, or blue. Recent experiments have demonstrated that a group of transcription factors are capable of converting fibroblasts into neuronal cells in vitro and that the process involves microRNAs. To better understand the process, Xue et al studied the role of a particular polypyrimidine-tract–binding protein (PTB) that is repressed during normal brain development by a microRNA, miR124, and is known to be involved in the regulation of splicing of mRNA.
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