Tohru Kawamoto

Simple synthesis of three primary colour nanoparticle inks of Prussian blue and its analogues

Historic Prussian blue (PB) pigment is easily obtained as an insoluble precipitate in quantitative yield from an aqueous mixture of Fe3+ and [FeII(CN)6]4? (Fe2+ and [FeIII(CN)6]3?). It has been found that the PB pigment is inherently an agglomerate of 10?20?nm nanoparticles, based on powder x-ray diffraction (XRD) line broadenings and transmission electron microscopy (TEM) images. The PB pigment has been revived as both organic-solvent-soluble and water-soluble nanoparticle inks. Through crystal surface modification with aliphatic amines, the nanoparticles are stably dispersed from the insoluble agglomerate into usual organic solvents to afford a transparent blue solution. Identical modification with [Fe(CN)6]4? yields water-soluble PB nanoparticles. A similar ink preparation is applicable to Ni-PBA and Co-PBA (nickel and cobalt hexacyanoferrates). The PB (blue), Ni-PBA (yellow), and Co-PBA (red) nanoparticles function as three primary colour inks.

Adsorption removal of cesium from drinking waters: a mini review on use of biosorbents and other adsorbents.

Radiocesium (Cs) removal from waters becomes an emerging issue after the Fukushima Daiichi Nuclear Power Plant Disaster, during which a total of approximately 3.3×10(16) Bq Cs was released to contaminate the environment. This mini-review provided a summary on literature works to develop efficient adsorbent for removing Cs from waters. Adsorbent made of raw and modified minerals, composites particles, and biosorbents that are highly specific to Cs in the presence of other alkali and alkali earth metals were summarized. Development of Prussian blue (PB) nanoparticles on Cs removal and its potential use in drinking waterworks was discussed. This review is a unique report for adsorption removal of Cs from contaminated waters.

Dealing with the aftermath of Fukushima Daiichi nuclear accident: decontamination of radioactive cesium enriched ash.

Environmental radioactivity, mainly in the Tohoku and Kanto areas, due to the long living radioisotopes of cesium is an obstacle to speedy recovery from the impacts of the Fukushima Daiichi Nuclear Power Plant accident. Although incineration of the contaminated wastes is encouraged, safe disposal of the Cs enriched ash is the big challenge. To address this issue, safe incineration of contaminated wastes while restricting the release of volatile Cs to the atmosphere was studied. Detailed study on effective removal of Cs from ash samples generated from wood bark, household garbage, and municipal sewage sludge was performed. For wood ash and garbage ash, washing only with water at ambient conditions removed radioactivity due to (134)Cs and (137)Cs, retaining most of the components other than the alkali metals with the residue. However, removing Cs from sludge ash needed acid treatment at high temperature. This difference in Cs solubility is due to the presence of soil particle originated clay minerals in the sludge ash. Because only removing the contaminated vegetation is found to sharply decrease the environmental radioactivity, volume reduction of contaminated biomass by incineration makes great sense. In addition, need for a long-term leachate monitoring system in the landfill can be avoided by washing the ash with water. Once the Cs in solids is extracted to the solution, it can be loaded to Cs selective adsorbents such as Prussian blue and safely stored in a small volume.

Novel Mechanism of Photoinduced Reversible Phase Transitions in Molecule-Based Magnets

A novel microscopic mechanism of bidirectional structural changes is proposed for the photoinduced magnetic phase transition in Co-Fe Prussian blue analogs on the basis of ab initio quantum chemical cluster calculations. It is shown that the local potential energies of various spin states of Co are sensitive to the number of nearest neighbor Fe vacancies. As a result, the forward and backward structural changes are most readily initiated by excitation of different local regions by different photons. This mechanism suggests an effective strategy to realize photoinduced reversible phase transitions in a general system consisting of two local components.

Pancreatic carcinoma: Correlation between E-cadherin and α-catenin expression status and liver metastasis

Dysfunction of the E‐cadherin/catenin‐mediated cell‐cell adhesion system has been associated with invasiveness and poor differentiation of human carcinomas. However, its importance in the genesis of liver metastasis has not been examined sufficiently.

Electrochromic Thin Film of Prussian Blue Nanoparticles Fabricated using Wet Process

Electrochromic thin films of Prussian blue nanoparticles were developed using wet processing. The resultant alkyl-ligand covered nanoparticles disperse well in organic solvents. Consequently, various conventional coating and printing methods can be used in high-quality micro-fabrication to prepare electronic devices. We examined electrochromic properties of the thin film fabricated using spin-coating method. Electrochromism of the thin film on an indium tin oxide (ITO) electrode was observed. The color changes from blue to colorlessness reversibly at potentials between +0.6 to -0.4 V. Furthermore, various patterns were printed on ITO substrates using photolithography, indicating potential application of this approach to information displays and smart windows.

Electrochromic Thin Film Fabricated Using a Water-Dispersible Ink of Prussian Blue Nanoparticles

We dispersed nanoparticles of Prussian blue (PB) in water using surface modification of the PB nanoparticles. Using spin-coating method, a thin film is easily fabricated with water dispersible ink of PB nanoparticles. The PB film thickness was estimated as 40–430 nm. The PB nanoparticle film on an indium tin oxide glass substrate showed a stable electrochromic response: the color changed repeatedly between blue and colorless without any post-treatment.

A theoretical model for ferromagnetism of TDAE-C60

Abstract A new mechanism to cause for ferromagnetism of C60 complexes with tetrakis(dimethylamino)ethylene (TDAE) is proposed. This mechanism is based on charge-transfer induced intramolecular Jahn-Teller (CTJT) distortion and intermolecular cooperative Jahn-Teller (CJT) distortion, and ferromagnetism is caused by orbital ordering. The magnitude of CTJT distortion has been estimated by semi-empirical molecular orbital (MO) calculations for a single C60 anion. The CJT distortion and ferromagnetism have been investigated with use of exact diagonalization procedure for one-dimensional multi-band Hubbard Hamiltonian. Finally we propose possible JT-distorted crystal structures which are likely to exhibit three-dimensional ferromagnetic ordering. We also suggest certain measurements which may confirm the proposed model.

Rapid measurement of radiocesium in water using a Prussian blue impregnated nonwoven fabric

We developed a rapid method for concentrating and measuring radiocesium (134Cs and 137Cs) dissolved in fresh water using nonwoven fabric impregnated with Prussian blue (PB) as a radiocesium absorber in combination with gamma-ray spectrometry using a germanium (Ge) detector. Utilizing this method, dissolved radiocesium in a 20–100 L freshwater sample could be concentrated within a period of 20–60 min by passing the sample through 10–12 columns, connected in series, that had been fitted with nonwoven fabric disks impregnated with PB. Laboratory tests using water samples containing known amounts of radiocesium confirmed that the overall recovery rate of the isotope was 100%–108%, and that the first six columns recovered 84%–97% of the isotope. The detection limit of this method was determined to be 0.002 Bq/L with a sample of 100 L and measurement time of 43,200 s. In comparison with traditional methods using ion-exchange resin, co-precipitation with ammonium phosphomolybdate, etc., our method has the advantages of reduced cost and a significantly shorter concentration time. Since water samples can be treated in short periods of time, it is now possible to conduct radiocesium pre-concentration in situ, thus eliminating the need to transport large-volume water samples to laboratories.

Preparation of electrochromic Prussian blue nanoparticles dispersible into various solvents for realisation of printed electronics

An insoluble solid of historic Prussian blue (PB) was transformed into dispersible PB nanoparticles in water and various hydrophilic and hydrophobic organic solvents. Via hybrid surface modification using Na4[FeII(CN)6] and short-chain alkylamines, the insoluble PB was successfully dispersed in hydrophilic-and-hydrophobic boundary alcohols, such as n-butanol. The n-butanol-dispersible PB nanoparticles afforded homogeneous spin-coated thin films on various substrates. The chemisorbed shorter-chain alkylamines, n-propylamines, of the PB nanoparticles were thermally released at 100 °C from their surfaces to present stubborn electrochromic PB thin films adhering to the substrate via mutual coordination-bonding networks.