Environmentally friendly coloured materials: cellulose/titanium dioxide/inorganic pigment composite spherical microbeads prepared by viscose phase-separation method

In order to develop environmentally friendly coloured materials, cellulose composite spherical microbeads hybridised with titanium dioxide (TiO₂) particles and inorganic pigment were prepared by a phase-separation method using viscose and an aqueous solution containing sodium polyacrylate. Findings regarding the relationships between cellulose xanthate and the electronic characteristics of TiO₂ particles used in the cellulose/inorganic material composite sphering process are also reported. These findings suggest that the location of TiO₂ particles in cellulose microbeads is related to electrical repulsion between the xanthate (CSS⁻) group and TiO₂. The use of TiO₂ powder as colour pigment is limited, as its colour is white. The cellulose composite spherical microbeads covered with TiO₂ and Fe₂O₃ particles were developed by addition of iron oxide (Fe₂O₃). Their surfaces were viewed by laser microscope and using SEM images. These composite microbeads retained the photocatalytic property of TiO₂. Cellulose/TiO₂/Fe₂O₃ composite spherical microbeads with both colour function and photocatalytic properties were successfully prepared.     

Strength and Phase Stability of Yttria-Ceria-Doped Tetragonal Zirconia/Alumina Composites Sintered and Hot Isostatically Pressed in Argon–Oxygen Gas Atmosphere

Yttria-ceria-doped tetragonal zirconia (Y,Ce)-TZP)/alumina (Al₂O₃) composites were fabricated by hot isostatic pressing at 1400° to 1450°C and 196 MPa in an Ar–O₂ atmosphere using the fine powders prepared by hydrolysis of ZrOCl₂ solution. The composites consisting of 25 wt% Al₂O₃ and tetragonal zirconia with compositions 4 mol% YO_1.5–4 mol% CeO₂–ZrO₂ and 2.5 mol% YO_1.5–5.5 mol% CeO₂–ZrO₂ exhibited mean fracture strength as high as 2000 MPa and were resistant to phase transformation under saturated water vapor pressure at 180°C (1 MPa). Postsintering hot isostatic pressing of (4Y, 4Ce)-TZP/Al₂O₃ and (2.5Y, 5.5Ce)-TZP/Al₂O₃ composites was useful to enhance the phase stability under hydrothermal conditions and strength.     

Anatase-Type TiO2 and ZrO2-Doped TiO2 Directly Formed from Titanium(III) Sulfate Solution by Thermal Hydrolysis: Effect of the Presence of Ammonium Peroxodisulfate on their Formation and Properties

Anatase-type TiO₂ powder containing sulfur with absorption in the visible region was directly formed as particles with crystallite in the range 15–88 nm by thermal hydrolysis of titanium(III) sulfate (Ti₂(SO₄)₃) solution at 100°–240°C. Because of the presence of ammonium peroxodisulfate ((NH₄)₂S₂O₈), the yield of anatase-type TiO₂ from Ti₂(SO₄)₃ solution was accelerated, and anatase with fine crystallite was formed. Anatase-type TiO₂ doped with ZrO₂ up to 9.8 mol% was directly precipitated as nanometer-sized particles from the acidic precursor solutions of Ti₂(SO₄)₃ and zirconium sulfate in the presence and the absence of (NH₄)₂S₂O₈ by simultaneous hydrolysis under hydrothermal conditions at 200°C. By doping ZrO₂ into TiO₂ and with increasing ZrO₂ content, the crystallite size of anatase was decreased, and the anatase-to-rutile phase transformation was retarded as much as 200°C. The anatase-type structure of ZrO₂-doped TiO₂ was maintained after heating at 1000°C for 1 h. The favorable effect of doping ZrO₂ to anatase-type TiO₂ on the photocatalytic activity was observed.     

Phase separation behavior and morphology development of phenolic resin/PMMA/hexamethylenetetrarnine blends

Summary In order to obtain materials with nanopores which will be applicable for many fields, the structures of the cured blends of phenolic resin (PhN), poly(methyl methacrylate) (PMMA) and curing agent were studied. After PMMA was extracted from cured blends, the structures of cured phenolic resins were observed with SEM. As a results, it was found that nanosized continuous pore structures were formed in extremely wide composition region if curing temperature was high.     

Proton conducting acid-base mixed materials under water-free condition

In recent years, a lot of attentions have been paid for a development of water-free polymer electrolyte membranes fuel cells (PEMFC) at intermediate temperatures (above 100 °C) because of many technological advantages of higher temperature operation. However, the proton conductivity of conventional polymer membranes under water-free condition is usually very low and the polymeric membranes are not stable at higher temperatures. So, the development of non-hydrous proton conducting membrane under water-free condition has been a state of the art issue in the advanced PEMFC technology. In this study, non-hydrous protonic conducting material was prepared by the mixing of acidic surfactant of mono-dodecylphosphate (MDP) and organic base of benzimidazole (BnIm). The proton conductivity and thermal stability of MDP-BnIm mixed material increased with the mixing ratio of BnIm. Maximum proton conductivity of MDP-BnIm mixed material (BnIm mixing ratio of 200 wt.%. vs. MDP) was found to be 1×10⁻³ S cm⁻¹ at 150 °C under water-free condition.     

Measurement of self-diffusion coefficients in Li ionic conductors by using the short-lived radiotracer of 8Li

For the effective use of short-lived radioactive beams, soon to be available at the Tokai Radioactive Ion Accelerator Complex, the authors have developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound βLiAl using an α-emitting radiotracer of ⁸Li (T_1/2=0.84 s). It was found that the time-dependent yields of the α particles from the diffusing ⁸Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in βLiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects (i.e., the existence of the atomic vacancies of Li and the defects in Ga sites that are replaced by Li).     

Excitations bound to a vortex line in layered superconductors

Using Bogoliubov-de Gennes equation, we study quasiparticle excitations in layered superconductors in the presence of a straight vortex line which is parallel to the layers. The lowest bound state is shown to have energy eigenvalue of the order of magnitude , the energy gap, in contrast to the corresponding value ²/E_F when the line is perpendicular to the layers.     

Metal Single-Atom Cocatalyst on Carbon Nitride for the Photocatalytic Hydrogen Evolution Reaction: Effects of Metal Species

Single-atom (SA) catalysts exhibit high activity in various reactions because there are no inactive internal atoms. Accordingly, SA cocatalysts are also an active research fields regarding photocatalytic hydrogen (H₂) evolution which can be generated by abundant water and sunlight. Herein, it is investigated whether 10 transition metal elements can work as an SA on graphitic carbon nitride (g-C₃N₄; i.e., gCN), a promising visible-light-driven photocatalyst. A method is established to prepare SA-loaded gCN at high loadings (weight of ≈3 wt.% for Cu, Ni, Pd, Pt, Rh, and Ru) by modulating the photoreduction power. Regarding Au and Ag, SAs are formed with difficulty without aggregation because of the low binding energy between gCN and the SA. An evaluation of the photocatalytic H₂-evolution activity of the prepared metal SA-loaded gCN reveals that Pd, Pt, and Rh SA-loaded gCN exhibits relatively high H₂-evolution efficiency per SA. Transient absorption spectroscopy and electrochemical measurements reveal the following: i) Pd SA-loaded gCN exhibits a particularly suitable electronic structure for proton adsorption and ii) therefore they exhibit the highest H₂-evolution efficiency per SA than other metal SA-loaded gCN. Finally, the 8.6 times higher H₂-evolution rate per active site of Pd SA is achieved than that of Pd-nanoparticles cocatalyst.     

Review of the International Symposium on Artificial Life and Robotics (AROB)

In this article, we review the growth of AROB conferences, and assess the various contributions, which have covered digital life, the artificial brain, artificial society, and evolutionary robots, etc. We analyze the relations between artificial life, complexity, and intelligent robots, and finally give our view of the expected future of AROB. This work was presented in part at the 5th International Symposium on Artificial Life and Robotics, Oita, Japan, January 26–28, 2000     

Detection of environmental changes from network structure

We studied the networks of the temperature record in the atmosphere. They are made by the strength of the synchronization, including the delay between temperatures at locations on Earth. We consider these locations as nodes, and we consider a pair of locations as a link if the synchronization between them is stronger than a threshold. The network is scale-free, which is thought to contribute to the stability of the climate. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007