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Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
Direct Imaging Of Human Swi/Snf-Remodeled Mono- And Polynucleosomes By Atomic Force Microscopy Employing Carbon Nanotube Tips, Gavin R. Schnitzler, Chin Li Cheung, Jason H. Hafner, Andrew J. Saurin, Robert E. Kingston, Charles M. Lieber
Direct Imaging Of Human Swi/Snf-Remodeled Mono- And Polynucleosomes By Atomic Force Microscopy Employing Carbon Nanotube Tips, Gavin R. Schnitzler, Chin Li Cheung, Jason H. Hafner, Andrew J. Saurin, Robert E. Kingston, Charles M. Lieber
Barry Chin Li Cheung Publications
Chromatin-remodeling complexes alter chromatin structure to facilitate, or in some cases repress, gene expression. Recent studies have suggested two potential pathways by which such regulation might occur. In the first, the remodeling complex repositions nucleosomes along DNA to open or occlude regulatory sites. In the second, the remodeling complex creates an altered dimeric form of the nucleosome that has altered accessibility to transcription factors. The extent of translational repositioning, the structure of the remodeled dimer, and the presence of dimers on remodeled polynucleosomes have been difficult to gauge by biochemical assays. To address these questions, ultrahigh-resolution carbon nanotube tip atomic …
Structural And Functional Imaging With Carbon Nanotube Afm Probes, J. H. Hafner, Chin Li Cheung, A. T. Woolley, C. M. Lieber
Structural And Functional Imaging With Carbon Nanotube Afm Probes, J. H. Hafner, Chin Li Cheung, A. T. Woolley, C. M. Lieber
Barry Chin Li Cheung Publications
Atomic force microscopy (AFM) has great potential as a tool for structural biology, a field in which there is increasing demand to characterize larger and more complex biomolecular systems. However, the poorly characterized silicon and silicon nitride probe tips currently employed in AFM limit its biological applications. Carbon nanotubes represent ideal AFM tip materials due to their small diameter, high aspect ratio, large Young’s modulus, mechanical robustness, well-defined structure, and unique chemical properties. Nanotube probes were first fabricated by manual assembly, but more recent methods based on chemical vapor deposition provide higher resolution probes and are geared towards mass production, …
Energy Gaps In “Metallic” Single-Walled Carbon Nanotubes, Min Ouyang, Jin-Lin Huang, Chin Li Cheung, Charles Lieber
Energy Gaps In “Metallic” Single-Walled Carbon Nanotubes, Min Ouyang, Jin-Lin Huang, Chin Li Cheung, Charles Lieber
Barry Chin Li Cheung Publications
Metallic single-walled carbon nanotubes have been proposed to be good one-dimensional conductors. However, the finite curvature of the graphene sheet that forms the nanotubes and the broken symmetry due to the local environment may modify their electronic properties. We used low-temperature atomically resolved scanning tunneling microscopy to investigate zigzag and armchair nanotubes, both thought to be metallic. “Metallic” zigzag nanotubes were found to have energy gaps with magnitudes that depend inversely on the square of the tube radius, whereas isolated armchair tubes do not have energy gaps. Additionally, armchair nanotubes packed in bundles have pseudogaps, which exhibit an inverse dependence …
Atomically Resolved Single-Walled Carbon Nanotube Intramolecular Junctions, Min Ouyang, Jin-Lin Huang, Chin Li Cheung, Charles M. Lieber
Atomically Resolved Single-Walled Carbon Nanotube Intramolecular Junctions, Min Ouyang, Jin-Lin Huang, Chin Li Cheung, Charles M. Lieber
Barry Chin Li Cheung Publications
Intramolecular junctions in single-walled carbon nanotubes are potentially ideal structures for building robust, molecular-scale electronics but have only been studied theoretically at the atomic level. Scanning tunneling microscopy was used to determine the atomic structure and electronic properties of such junctions in single-walled nanotube samples. Metal-semiconductor junctions are found to exhibit an electronically sharp interface without localized junction states, whereas a more diffuse interface and low-energy states are found in metal-metal junctions. Tight-binding calculations for models based on observed atomic structures show good agreement with spectroscopy and provide insight into the topological defects forming intramolecular junctions. These studies have important …