Biomedical subjects

Toshinari Ichihashi

Publications and source records attributed to Toshinari Ichihashi.

3 recordsLinked to original sources

PubMed2005

Controlling the incorporation and release of C60 in nanometer-scale hollow spaces inside single-wall carbon nanohorns.

We succeeded in large-scale preparation of single-wall carbon nanohorns (SWNH) encapsulating C60 molecules in a liquid phase at room temperature using a "nano-precipitation" method, that is, complete evaporation of the toluene from a C60-SWNH-toluene mixture. The C60 molecules were found to occupy 6-36% of the hollow space inside the SWNH, depending on the initial quantity of C60. We showed that the C60 in C60@SWNHox was quickly released in toluene, and the release rate decreased by adding ethanol to toluene. Numerical analysis of the release profiles indicated that there were fast and slow release processes. We consider that the incorporation quantity and the release rate of C60 were controllable in/from SWNHs because SWNHs have large diameters, 2-5 nm.

Journal Article↗

PubMed2004

In situ observation of carbon-nanopillar tubulization caused by liquidlike iron particles.

The tubulization process of amorphous carbon nanopillars was observed in situ by transmis-sion electron microscopy. Amorphous carbon nanopillars were transformed into graphitic tubules by annealing at 650-900 degrees C in the presence of iron nanoparticles. A molten catalyst nanoparticle penetrated an amorphous carbon nanopillar, dissolving it, and leaving a graphite track behind. An iron nanoparticle moved with its shape changing like an earthworm. We concluded that the tubulization mechanism is a solid-(quasiliquid)-solid mechanism where the carbon phase transformation is a kind of liquid phase graphitization of amorphous carbon catalyzed by liquefied metal-carbon alloy nanoparticles.

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PubMed2002

Energy-filtered electron diffraction and high-resolution electron microscopy on short-range ordered structure in GaAs(0.5)Sb(0.5).

Characteristic intensity distribution of diffuse scattering in III-V alloy semiconductor GaAs(0.5)Sb(0.5) epitaxially grown was observed by the energy-filtered electron diffraction method with [110] incidence. The diffuse scattering situates at the one-third positions between the fundamental reflections extending parallel to the q002 direction in the reciprocal space. A high-resolution electron microscope image shows weak contrast modulation corresponding to the diffuse scattering. The image processed with the Fourier transform by selecting the diffuse scattering and a fundamental reflection shows small regions consisting of bright dots being elongated along the (111) planes and aligning on the (002) planes, which are considered to result from the ordering of As and Sb during the growth process. The effect of including the fundamental reflection for imaging the ordered regions in the image processing method is also discussed. Finally, based on the results obtained by energy-filtered electron diffraction and high-resolution electron microscopy, a simple structure model for the short-range ordered structure in GaAs(0.5)Sb0.5 is proposed.

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