For the development of biofunctional carbon nanotubes for biosensors, drug carriers, and nanobiocatalysts, their aggregation and biofouling in aqueous solutions are crucial problems because this behavior leads to a reduction of their excellent optical and electrical properties and nanoscale size effects. This paper presents a new method for enhancing the dispersibility of protein-carbon nanotube conjugates and for exfoliating the protein from the carbon nanotube sidewalls through controlling the concentration of guanidine hydrochloride (Gdn·HCl) in the solution. In medium concentrations (2-3 M) of Gdn·HCl, the dispersibility of protein-carbon nanotube conjugates was found to be substantially increased without denaturation or aggregation of the proteins. At higher concentrations (>6 M) of Gdn·HCl, pristine carbon nanotubes were precipitated instantly as a result of dissociation of the protein. These phenomena indicate that Gdn·HCl functions not only as a dispersion adjuvant for biofunctional protein-carbon nanotube conjugates, but also as a cleaning agent for the purification of biofouled carbon nanotubes. The dissociation concentrations of Gdn·HCl were higher than the midpoint of protein denaturation, suggesting that protein adsorption on carbon nanotubes is more stable than protein folding toward Gdn·HCl.

We demonstrated a new process for synthesizing a graphene sheet at the interface between solid amorphous carbon and liquid gallium. The insolubility of carbon in gallium strongly restricted the depth of graphitization, but a multilayered graphene sheet having four to six layers of graphene was produced over the entire area of the interface immediately beneath the liquid gallium. We also demonstrated the operation of an electric-field-effect device fabricated on the multilayered graphene with a back-gated configuration, and a maximum conductance modulation of 40% was observed for an applied gate voltage ranging from -100 to +100 V.

A method for fabricating single-crystalline nanogaps on Si substrates was developed. Polycrystalline Pt nanowires on Si substrates were broken down by current flow under various gaseous environments. The crystal structure of the nanogap electrode was evaluated using scanning electron microscopy and transmission electron microscopy. Nanogap electrodes sandwiched between Pt-large-crystal-grains were obtained by the breakdown of the wire in an O(2) or H(2) atmosphere. These nanogap electrodes show intense spots in the electron diffraction pattern. The diffraction pattern corresponds to Pt (111), indicating that single-crystal grains are grown by the electrical wire breakdown process in an O(2) or H(2) atmosphere. The Pt wires that have (111)-texture and coherent boundaries can be considered ideal as interconnectors for single molecular electronics. The simple method for fabrication of a single-crystalline nanogap is one of the first steps toward standard nanogap electrodes for single molecular instruments and opens the door to future research on physical phenomena in nanospaces.

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The authors found that an extremely thin resist pattern on a silicon dioxide can be directly transformed into a graphene channel through interfacial graphitization of liquid gallium. These patterned graphene field effect transistors show p-type field effect conductance characteristics and a maximum conductance modulation of 100% against an applied gate voltage range from −50 to +50 V at room temperature, which is almost identical to the on/off ratio of 2. These conductance modulation ratios improved with decreasing the initial resist thickness below 2 nm; however, the absolute value of the channel conductance also deteriorated with decreasing the resist thickness, suggesting that electron scattering at the domain boundary dominates the channel conductance.

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Abstract. We propose a web system called CiVo (City Voice) that is capable of visualizing public conversations on the Internet. It monitors the posting on the Twitter with respect to a set of specific phrases and displays the correspondent movie clips with cartoons on the time line on CiVo when it finds them. It extends the Twitter to a visual social medium that allows people to share what happens in the world at a glance. The main loop of CiVo runs on PHP while monitoring the Twitter using its API and it returns a specific SWF file to the HTTP clients for each GET request. The SWF file always updates its subSWFs reflecting the phrases found on the Twitter.