Raman spectrum of graphene and graphene layers.
TL;DR: This work shows that graphene's electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers, and allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.
Abstract: Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process The G peak slightly down-shifts This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area
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TL;DR: In this paper, a reduced graphene oxide (RGO) on nickel hydroxide (Ni(OH)2) film was synthesized via a green and facile hydrothermal approach.
189 citations
TL;DR: Comparison with other pretreatment methods reveals the importance of copper surface morphology and the critical role of the melting-resolidification pretreatment and the effect of important growth process parameters is studied to determine their roles in achieving low nucleation density.
Abstract: We present a facile method to grow millimeter-size, hexagon-shaped, monolayer, single-crystal graphene domains on commercial metal foils. After a brief in situ treatment, namely, melting and subsequent resolidification of copper at atmospheric pressure, a smooth surface is obtained, resulting in the low nucleation density necessary for the growth of large-size single-crystal graphene domains. Comparison with other pretreatment methods reveals the importance of copper surface morphology and the critical role of the melting–resolidification pretreatment. The effect of important growth process parameters is also studied to determine their roles in achieving low nucleation density. Insight into the growth mechanism has thus been gained. Raman spectroscopy and selected area electron diffraction confirm that the synthesized millimeter-size graphene domains are high-quality monolayer single crystals with zigzag edge terminations.
189 citations
189 citations
TL;DR: In this article, the authors present a comprehensive study of graphene grown by chemical vapor deposition on copper single crystals with exposed (1, 0, 0), (1, 1, 0) and (1 1, 1, 1) faces, and report an exceptionally narrow 2D band width caused by the interaction between graphene and metallic substrate.
188 citations
Cites background from "Raman spectrum of graphene and grap..."
...there are still several debatable issues. The 2D band has been regarded as a single Lorentzian with FWHM of ~ 24 cm-1 for graphene on Si/SiO 2 or broader depending on the substrate and/or environment [34, 69]. As it turned out recently, free standing graphene exhibits narrower (~ 22 cm-1) 2D band with a bimodal lineshape [59, 70, 71]. 14 Similar subfeatures were observed also for the unstrained graphene o...
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...phonon wavevectors contributing to the 2D mode – along K-Γ (so called inner) or K-M (outer) high symmetry lines. Earlier works usually assumed a preferential contribution of the latter to the 2D mode [66, 68, 69], but recent works point to a larger importance of the inner phonons [62, 72, 73, 75]. However, the simple one-dimensional picture is now being superseded by a full two-dimensional description of the ...
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TL;DR: This work examines the structural and chemical changes of silk proteins systematically at temperatures above the onset of thermal degradation to provide a mechanism for the thermal transition of the protein and demonstrate a potential strategy for designing pyroproteins using a clean system with a catalyst-free aqueous wet process for in vivo applications.
Abstract: Silk proteins are of great interest to the scientific community owing to their unique mechanical properties and interesting biological functionality. In addition, the silk proteins are not burned out following heating, rather they are transformed into a carbonaceous solid, pyroprotein; several studies have identified potential carbon precursors for state-of-the-art technologies. However, no mechanism for the carbonization of proteins has yet been reported. Here we examine the structural and chemical changes of silk proteins systematically at temperatures above the onset of thermal degradation. We find that the β-sheet structure is transformed into an sp(2)-hybridized carbon hexagonal structure by simple heating to 350 °C. The pseudographitic crystalline layers grew to form highly ordered graphitic structures following further heating to 2,800 °C. Our results provide a mechanism for the thermal transition of the protein and demonstrate a potential strategy for designing pyroproteins using a clean system with a catalyst-free aqueous wet process for in vivo applications.
188 citations
References
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28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations