65 research outputs found

    Embedded arrays of vertically aligned carbon nanotube carpets and methods for making them

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    According to some embodiments, the present invention provides a system and method for supporting a carbon nanotube array that involve an entangled carbon nanotube mat integral with the array, where the mat is embedded in an embedding material. The embedding material may be depositable on a carbon nanotube. A depositable material may be metallic or nonmetallic. The embedding material may be an adhesive material. The adhesive material may optionally be mixed with a metal powder. The embedding material may be supported by a substrate or self-supportive. The embedding material may be conductive or nonconductive. The system and method provide superior mechanical and, when applicable, electrical, contact between the carbon nanotubes in the array and the embedding material. The optional use of a conductive material for the embedding material provides a mechanism useful for integration of carbon nanotube arrays into electronic devices

    Selective functionalization of carbon nanotubes

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    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations

    Single Wall Carbon Nanotube Fibers Extruded from Super-Acid Suspensions: Preferred Orientation, Electrical and Thermal Transport

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    Fibers of single wall carbon nanotubes extruded from super-acid suspensions exhibit preferred orientation along their axes. We characterize the alignment by x-ray fiber diagrams and polarized Raman scattering, using a model which allows for a completely unaligned fraction. This fraction ranges from 0.17 to 0.05±0.02 for three fibers extruded under different conditions, with corresponding Gaussian full widths at half-maximum (FWHM) from 64o to 44o±2o. FWHM, aligned fraction, electrical and thermal transport all improve with decreasing extrusion orifice diameter. Resistivity, thermoelectric power and resonant-enhanced Raman scattering indicate that the neat fibers are strongly p-doped; the lowest observed ρ is 0.25mΩcm at 300 K. High temperature annealing increases ρ by more than 1 order of magnitude and restores the Raman resonance associated with low-energy van Hove transitions, without affecting the nanotube alignment

    Macroscopic Neat Single-Walled Carbon Nanotubes Fibers

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    The first-ever well-aligned continuous macroscopic neat single-walled carbon nanotube (SWNT) fibers were produced using conventional spinning techniques. Neat SWNT fibers, containing no surfactant or polymer, were made by spinning dispersions of SWNTs in 102% sulfuric acid into different coagulants. The critical role of sulfuric acid in dispersing and aligning SWNTs during fiber formation has been explored. Characterization shows alignment greater than any other macroscopic neat SWNT material reported to-date while providing insight into the fundamental hierarchy and nature of SWNT fiber formation. Electrical, thermal, and mechanical measurements indicate that neat SWNT fibers hold tremendous potential for future applications

    Human Cytomegalovirus IE1 Protein Elicits a Type II Interferon-Like Host Cell Response That Depends on Activated STAT1 but Not Interferon-Ξ³

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    Human cytomegalovirus (hCMV) is a highly prevalent pathogen that, upon primary infection, establishes life-long persistence in all infected individuals. Acute hCMV infections cause a variety of diseases in humans with developmental or acquired immune deficits. In addition, persistent hCMV infection may contribute to various chronic disease conditions even in immunologically normal people. The pathogenesis of hCMV disease has been frequently linked to inflammatory host immune responses triggered by virus-infected cells. Moreover, hCMV infection activates numerous host genes many of which encode pro-inflammatory proteins. However, little is known about the relative contributions of individual viral gene products to these changes in cellular transcription. We systematically analyzed the effects of the hCMV 72-kDa immediate-early 1 (IE1) protein, a major transcriptional activator and antagonist of type I interferon (IFN) signaling, on the human transcriptome. Following expression under conditions closely mimicking the situation during productive infection, IE1 elicits a global type II IFN-like host cell response. This response is dominated by the selective up-regulation of immune stimulatory genes normally controlled by IFN-Ξ³ and includes the synthesis and secretion of pro-inflammatory chemokines. IE1-mediated induction of IFN-stimulated genes strictly depends on tyrosine-phosphorylated signal transducer and activator of transcription 1 (STAT1) and correlates with the nuclear accumulation and sequence-specific binding of STAT1 to IFN-Ξ³-responsive promoters. However, neither synthesis nor secretion of IFN-Ξ³ or other IFNs seems to be required for the IE1-dependent effects on cellular gene expression. Our results demonstrate that a single hCMV protein can trigger a pro-inflammatory host transcriptional response via an unexpected STAT1-dependent but IFN-independent mechanism and identify IE1 as a candidate determinant of hCMV pathogenicity

    Swept Under the Rug? A Historiography of Gender and Black Colleges

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