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As a two-dimensional carbon nanomaterial, graphene has a high surface area and good chemical stability; therefore, its potential applicability in composite materials and as a catalyst support is high. Here, we report a facile process to decorate graphene sheets with well-dispersed Pd nanoparticles. By the in situ formation and adhesion of Pd nanoparticles to the thermally exfoliated graphene (TEG) sheets suspended in a solvent, a Pd/TEG composite was prepared and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer−Emmett−Teller (BET) surface area analysis. The migration and aggregation of Pd nanoparticles on the graphene sheets was directly observed by scanning transmission electron microscopy. As the composite was heated to 700 °C, there was little movement of the Pd nanoparticles; on heating to 800 °C, well below the melting temperature, the Pd nanoparticles began to migrate, coalesce, and agglomerate to form larger particles. The aggregation behavior was further confirmed by X-ray diffraction analysis of the Pd/TEG composite before and after being annealed at 800 °C. The graphene sheets provided a real-time imaging platform with nanometer-scale thickness to study the thermal stability and migratory behavior of nanoscale materials. [ABSTRACT FROM AUTHOR]

Continued growth is a way of growing nanotubes targeted to produce continuous and chirality-controlled single-walled carbon nanotube (SWNT) materials. This growth method strongly depends on efficient preparation of open-ended SWNT substrates. Nanoscopically flat open-ended SWNT substrates have been prepared by cutting the SWNT spun fiber with a focused ion beam cutting technique and followed by etching schemes for cleaning amorphous carbon and opening the ends of the SWNTs. The open ends were effectively characterized through selective etch back of open SWNT ends by carbon dioxide gas at 950 °C. High density continued growth was demonstrated from these nanoscopically flat open-ended substrates. [ABSTRACT FROM AUTHOR]

A wide-field four-channel fluorescence imager has been developed. The instrument uses four expanded laser beams to image a large section (6 mm×9 mm). An object can be sequentially illuminated with any combination of 408-, 532-, 658-, and 784-nmlasers for arbitrary (down to 1 ms) exposure times for each laser. Just two notch filters block scattered light from all four lasers. The design approach described here offers great flexibility in treatment of objects, very good sensitivity, and a wide field of view at low cost. There appears to be no commercial instrument capable of simultaneous fluorescence imaging of a wide field of view with four-laser excitation. Some possible applications are following events such as flow and mixing in microchannel systems, the transmission of biological signals across a culture, and following simulations of biological membrane diffusion. It can also be used in DNA sequencing by synthesis to follow the progress of the photolytic removal of dye and terminator. Without utilizing its time resolution, it can be used to obtain four independent images of a single tissue section stained with four targeting agents, with each coupled to a different dye matching one of the lasers. [ABSTRACT FROM AUTHOR]