Mikiya Matsuura

Synthetic models for the active site of cytochrome P450

Abstract As cytochrome P450 models, two kinds of iron porphyrins were synthesized, each of which has an alkanethiolate axial ligand and hydroxyl groups inside the molecular cavities. The stable dioxygen adducts were obtained by the reaction of the ferric complexes with KO 2 under an oxygen atmosphere. This study first demonstrated a hydrogen bond to bound dioxygen in an oxy form of a thiolate-coordinated heme model system. These results are discussed in relation to the process of dioxygen binding and activation in cytochrome P450.

Novel block copolymer templates for tuning mesopore connectivity in cage-type mesoporous silica films

Mesoporous silica films with large spherical mesopores are synthesized using new laboratory-made polystyrene-block-polybutadiene-block-polystyrene based triblock copolymers in which the polystyrene block is functionalized with hydrophilic sulfonic groups. When the relative weight of the copolymer to silica source is in the range from 10 to 70 mass%, spherical mesopores with uniform sizes can be formed in the films. In addition, when the ratio is lower than 20 mass%, spherical mesopores are separated by thick silica walls in the films. Nevertheless, owing to the presence of small-sized mesopores in the silica walls, all the spherical mesopores are accessible from the outside. With the gradual increase of the chosen copolymer/silica ratios, the distance between neighboring mesopores is reduced without a significant change of the original mesopore size, which has not been observed in previous reports using other block copolymers as templates.

Synthesis of mesoporous antimony-doped tin oxide (ATO) thin films and investigation of their electrical conductivity

Mesoporous antimony-doped tin oxide (ATO) thin films with crystallized frameworks are synthesized by using a laboratory-made thermally-stable triblock copolymer (named as ‘sulfonated HmSEBmS’) as the template at optimized conditions. The porous structure is strongly affected by the amount of copolymer, which causes variation in the electrical conductivity of the synthesized ATO films.

Measurement of swallowing using flexible polymer sensor

We proposed a new method to measure swallowing in this study. A flexible polymer sensor was used to measure human swallowing. Electromyogram (EMG) of suprahyoid muscles were measured as a reference of swallowing. We also developed a measurement system for the flexible polymer sensor, which consists of two measurement circuits; the 1st one measures the voltage of flexible polymer sensor, and the 2nd one EMG of suprahyoid muscles. We conducted measurement experiments focused on human swallowing to confirm the ability of this sensor. At the experiment one subject was asked to sit in three different postures and to drink a cup of water. Results show that human swallowing can be detected by this flexible polymer sensor.

Tuning wall thicknesses in mesoporous silica films for optimization of optical anti-reflective properties

This work reports the fabrication of mesoporous silica films with controllable wall thicknesses by spin coating of precursor solutions consisting of polystyrene-block-polybutadiene-block-polystyrene based triblock copolymers (Hydrogenated methyl Styrene Ethylene Butadiene methyl Styrene, HmSEBmS) and tetraethyl orthosilicate (TEOS) followed by calcination in air at 600 °C, for optical anti-reflection films. By changing the relative weight of the triblock polymer to TEOS, the pore-to-pore distance in the mesoporous silica film can be controlled without significantly affecting the size of the mesopores, thus, enabling effective control of the refractive index and porosity of the films. In terms of optical properties, the transmittance of the fabricated mesoporous silica film is approximately 3.3% higher than that of the uncoated glass substrate in the wavelength range of 400 to 750 nm.