Carbon Layer Formation on Hexagonal Boron Nitride by Plasma Processing in Hydroquinone Aqueous Solution.

Although hexagonal boron nitride (hBN) is a thermally conductive and electrically insulating filler in composite materials, surface modification remains difficult, which limits its dispersibility and functionalization. In this study, carbon layer formation on hBN particles by plasma processing in hydroquinone aqueous solution was investigated as a surface modification technique. Carbon components with features of polymeric hydrogenated amorphous carbon were found to be uniformly distributed on the hydroquinone-aided plasma-modified hBN (HQpBN) particles.

Soft X-ray emission spectroscopy for the electronic state of water molecules influenced by plasma-treated multi-walled carbon nanotubes.

In this study, soft X-ray emission spectroscopy of an aqueous colloidal dispersion of multi-walled carbon nanotubes modified via the plasma process in an aqueous solution was performed for investigating the electronic state of water molecules on the colloidal particles. In the aqueous dispersion, reconstruction of the hydrogen-bonded network was implied by the O 1s spectral changes in the 1b1' and 1b1'' peaks. Furthermore, the O 1s spectral intensity around the 3a1 state was enhanced to an unusually broad energy range in comparison with previous studies.

Thermal Decomposition Behavior of Prussian Blue in Various Conditions.

Prussian blue analogs (PBA) are widely studied for radioactive cesium decontamination. However, there are fewer works related to their post use storage. Considering the oxidative stabilization of the material after the selective uptake of Cs, the thermogravimetric properties in powder and bead form, with various Cs and other alkali metal ions adsorbed, and various heating rates were studied.

Dynamics of solvated electrons during femtosecond laser-induced plasma generation in water.

We studied the dynamics of solvated electrons in the early stage of plasma generation in water induced with an intense femtosecond laser pulse. According to the decay kinetics of solvated electrons, a fast recombination process of solvated electrons (geminate recombination) occurred with a more prolonged lifetime (500 ps to 1 ns) than that observed in previous pulse photolysis studies (10-100 ps). This unusually longer lifetime is attributed to additional production of solvated electrons due to abundant free electrons generated with the laser-induced plasma, implying significant influence of free electrons on the dynamics of solvated electrons.

Slide-Ring Material/Highly Dispersed Graphene Oxide Composite with Mechanical Strength and Tunable Electrical Conduction as a Stretchable-Base Substrate.

The development of stretchable elastomer composites with considerable mechanical strength and electrical conductivity is desired for future applications in communication tools, healthcare, and robotics. Herein, we have developed a novel stretchable elastomer composite by employing a slide-ring (SR) material as a matrix for restoration and graphene oxide (GO) as a precursor for a conductive filler. Highly dispersed GO in an organic solvent, prepared via a new method developed by the authors, allowed the uniform dispersion of GO into the matrix by simply mixing the solvent and SR.

Production of water-dispersible reduced graphene oxide without stabilizers using liquid-phase photoreduction.

We successfully produced water-dispersible reduced graphene oxide (rGO) by pH tuning liquid-phase photoreduction. In this method, the stabilizers and chemical modification usually used for dispersing rGO are not required. The stable carboxyl groups continue to ionize throughout the photoreduction process under alkaline conditions and continue to provide water-dispersible rGO.

Historical Pigment Exhibiting Ammonia Gas Capture beyond Standard Adsorbents with Adsorption Sites of Two Kinds.

Prussian blue is a historical pigment synthesized for the first time at the beginning of 18th century. Here we demonstrate that the historical pigment exhibits surprising adsorption properties of gaseous ammonia. Prussian blue shows 12.

Application of Prussian blue nanoparticles for the radioactive Cs decontamination in Fukushima region.

Cs decontamination efficiencies of the composites of iron hexacyanoferrate nanoparticles were investigated in comparison with commercial Prussian blue and natural zeolite. In pure water solution, the adsorption rate varied with sizes. In ash extract, where Cs adsorbing ability of zeolite was sharply dropped due to its poor selectivity, the impact of coexisting ions was negligible for FeHCF.

Oxygen diffusion and nonstoichiometry in BiFeO3.

Leakage current is a serious problem for the use of ferroelectricity in room-temperature multiferroics BiFeO3, and oxygen nonstoichiometry is considered as one of its principal origins. In order to establish a method to control oxygen content in the compound, we investigated the annealing process of stoichiometric BiFeO3 grains in air and revealed that oxygen diffusion occurs in two steps: (1) the weight of the sample decreases in a short time, which originates from the generation of oxygen deficiency near the surface of the grains; and then (2) it increases gradually and slowly, which originates from oxygen diffusion toward equilibrium in the inner part of the grains, introducing excess oxygen there. Step 1 causes the leakage current, and step 2 tends to cause inhomogeneity of oxygen content as well as the leakage current.

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.

Near-infrared spectroscopic study of a water-in-supercritical CO2 microemulsion as a function of the water content.

A water-in-supercritical CO(2) microemulsion is a reverse micelle encapsulating a nanometer-size water droplet dispersed in supercritical CO(2). In the microemulsion solution, water exists not only in the reverse micelle but also in the solvent CO(2). For quantitative analysis of the water distribution, near-infrared spectra of water + CO(2) and water + surfactant + CO(2) mixtures were measured over a wide range of water/CO(2) ratios from 0.

Hydrothermal Synthesis of Metal Oxide Nanoparticles in Supercritical Water.

This paper summarizes specific features of supercritical hydrothermal synthesis of metal oxide particles. Supercritical water allows control of the crystal phase, morphology, and particle size since the solvent's properties, such as density of water, can be varied with temperature and pressure, both of which can affect the supersaturation and nucleation. In this review, we describe the advantages of fine particle formation using supercritical water and describe which future tasks need to be solved.

Hydrothermal synthesis of crystalline rectangular titanoniobate particles.

Potassium titanoniobate (KTiNbO5) crystalline powders possessing rectangular particle shapes and large surface areas which are prerequisite for high photocatalytic performance have been successfully synthesized by a novel hydrothermal method.

Synthesis of Ag and AgI quantum dots in AOT-stabilized water-in-CO2 microemulsions.

Silver and silver iodide nanocrystals have been synthesized in the water-in-CO(2) reverse microemulsions formed by the commonly used surfactant, sodium bis(2-ethylhexyl)sulfosuccinate (AOT), in the presence of 2,2,3,3,4,4,5,5-octafluoro-1-pentanol as cosurfactant. The nanometer-sized aqueous domains in the microemulsion cores not only act as nanoreactors, but the surfactant interfacial monolayer also helps the stabilization of the metal and semiconductor nanoparticles. The transmission electron microscopy results show that silver and silver iodide nanocrystals with average diameters of 6.