Periodic Grain Boundaries Formed by Thermal Reconstruction of Polycrystalline Graphene Film

Grain boundaries consisting of dislocation cores arranged in a periodic manner have well-defined structures and peculiar properties and can be potentially applied as conducting circuits, plasmon reflectors and phase retarders. Pentagon-heptagon (5–7) pairs or pentagon-octagon-pentagon (5–8–5) carbon rings are known to exist in graphene grain boundaries. However, there are few systematic experimental studies on the formation, structure and distribution of periodic grain boundaries in graphene. Herein, scanning tunneling microscopy (STM) was applied to study periodic grain boundaries in monolayer graphene grown on a weakly interacting Cu(111) crystal. The periodic grain boundaries are formed after the thermal reconstruction of aperiodic boundaries, their structures agree well with the prediction of the coincident-site-lattice (CSL) theory. Periodic grain boundaries in quasi-freestanding graphene give sharp local density of states (LDOS) peaks in the tunneling spectra as opposed to the broad peaks of the aperiodic boundaries. This suggests that grain boundaries with high structural quality can introduce well-defined electronic states in graphene and modify its electronic properties

Studying Edge Defects of Hexagonal Boron Nitride Using High-Resolution Electron Energy Loss Spectroscopy

Studying the phonons of hexagonal boron nitride (h-BN) is important for understanding its thermal, electronic, and imaging applications. Herein, we applied high-resolution electron energy loss spectroscopy (HREELS) to monitor the presence of edge defects in h-BN films. We observed an edge phonon at 90.5 meV with the initial formation of island-like domains on Ru(0001), which subsequently weakens with respect to the bulk phonon as the islands congregate into a film. The presence of a weak edge phonon peak even at full surface coverage of the h-BN film indicates the sensitivity of HREELS in detecting line defects. A shoulder peak at ∼160 meV assignable to sp³ bonded modes was attributed to grain boundaries arising from misaligned domains. In addition, the strengths of substrate interaction and the rippling of the h-BN film can be judged from the shift in the phonon energy of the out-of-plane TO_⊥ mode

Additional file 1 of Chemotherapy and targeted therapy for advanced biliary tract cancers: an umbrella review

Additional file 1

Additional file 3 of Chemotherapy and targeted therapy for advanced biliary tract cancers: an umbrella review

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Additional file 4 of Chemotherapy and targeted therapy for advanced biliary tract cancers: an umbrella review

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Lattice Relaxation at the Interface of Two-Dimensional Crystals: Graphene and Hexagonal Boron-Nitride

Heteroepitaxy of two-dimensional (2D) crystals, such as hexagonal boron nitride (BN) on graphene (G), can occur at the edge of an existing heterointerface. Understanding strain relaxation at such 2D laterally fused interface is useful in fabricating heterointerfaces with a high degree of atomic coherency and structural stability. We use in situ scanning tunneling microscopy to study the 2D heteroepitaxy of BN on graphene edges on a Ru(0001) surface with the aim of understanding the propagation of interfacial strain. We found that defect-free, pseudomorphic growth of BN on a graphene edge “substrate” occurs only for a short distance (<1.29 nm) perpendicular to the interface, beyond which misfit zero-dimensional dislocations occur to reduce the elastic strain energy. Boundary states originating from a coherent zigzag-linked G/BN boundary are observed to greatly enhance the local conductivity, thus affording a new avenue to construct one-dimensional transport channels in G/BN hybrid interface

Additional file 2 of Chemotherapy and targeted therapy for advanced biliary tract cancers: an umbrella review

Additional file 2

Electrochemical Delamination of CVD-Grown Graphene Film: Toward the Recyclable Use of Copper Catalyst

The separation of chemical vapor deposited (CVD) graphene from the metallic catalyst it is grown on, followed by a subsequent transfer to a dielectric substrate, is currently the adopted method for device fabrication. Most transfer techniques use a chemical etching method to dissolve the metal catalysts, thus imposing high material cost in large-scale fabrication. Here, we demonstrate a highly efficient, nondestructive electrochemical route for the delamination of CVD graphene film from metal surfaces. The electrochemically delaminated graphene films are continuous over 95% of the surface and exhibit increasingly better electronic quality after several growth cycles on the reused copper catalyst, due to the suppression of quasi-periodical nanoripples induced by copper step edges. The electrochemical delamination process affords the advantages of high efficiency, low-cost recyclability, and minimal use of etching chemicals

The forest for detection of ACA and LA as risk factors for RVO.

<p>The forest for detection of ACA and LA as risk factors for RVO.</p

The forest for detection of APLA as a risk factor for RVO.

<p>The forest for detection of APLA as a risk factor for RVO.</p