Synthesis and Photocatalytic Activity of Poly(triazine imide)

Poly(triazine imide) was synthesized with incorporation of Li⁺ and Cl^? ions (PTI/Li⁺Cl^?) to form a carbon nitride derivative. The synthesis of this material by the temperature‐induced condensation of dicyandiamide was examined both in a eutectic mixture of LiCl–KCl and without KCl. On the basis of X‐ray diffraction measurements of the synthesized materials, we suggest that a stoichiometric amount of LiCl is necessary to obtain the PTI/Li⁺Cl^? phase without requiring the presence of KCl at 873 K. PTI/Li⁺Cl^? with modification by either Pt or CoO_x as cocatalyst photocatalytically produced H₂ or O₂, respectively, from water. The production of H₂ or O₂ from water indicates that the valence and conduction bands of PTI/Li⁺Cl^? were properly located to achieve overall water splitting. The treatment of PTI/Li⁺Cl^? with [Pt(NH₃)₄]²⁺ cations enabled the deposition of Pt through ion exchange, demonstrating photocatalytic activity for H₂ evolution, while treatment with [PtCl₆]^2? anions resulted in no Pt deposition. This was most likely because of the preferential exchange between Li⁺ ions and [Pt(NH₃)₄]²⁺ cations.     

Observation of long-distance radial correlation in toroidal plasma turbulence

This Letter presents the discovery of macroscale electron temperature fluctuations with a long radial correlation length comparable to the plasma minor radius in a toroidal plasma. Their spatiotemporal structure is characterized by a low frequency of ～1-3 kHz, ballistic radial propagation, a poloidal or toroidal mode number of m/n=1/1 (or 2/1), and an amplitude of ～2% at maximum. Nonlinear coupling between the long-range fluctuations and the microscopic fluctuations is identified. A change of the amplitude of the long-range fluctuation is transmitted across the plasma radius at the velocity which is of the order of the drift velocity.     

Preparation and characterization of hydrophobic calcium hydroxyapatite particles grafting oleylphosphate groups

Grafting of oleylphosphate (OP) molecules to the surface of calcium hydroxyapatite particles (HAP) was carried out by a coprecipitation method with a Ca(OH)₂–H₃PO₄ system in the presence of disodium oleylphosphate (DSOP). All the particles exhibited a single-crystal nature with rod-like shape and were elongated along c-axis from 36 to 122 nm in particle length with an increase in the concentration of DSOP. It was suggested that 084% of the phosphate ions exposed on the ac or bc faces of the HAP particles are exchanged with phosphate ions of DSOP molecules directing oleyl groups outward. The hydrophobicity of OP-grafted HAP particles was enhanced with an increase in the DSOP concentration. This high surface hydrophobicity was further confirmed by water adsorption experiments. The materials with the surface oleyl groups adsorbed much less water than the HAP particles produced without DSOP.     

Unconventional pairing originating from disconnected Fermi surfaces in the iron-based superconductor

For the iron-based high T_c superconductor LaFeAsO_1?xF_x, we construct a minimal model, where all of the five Fe d bands turn out to be involved. We then investigate the origin of superconductivity with a five-band random-phase approximation by solving the Eliashberg equation. We conclude that the spin fluctuation modes arising from the nesting between the disconnected Fermi pockets realise, basically, an extended s-wave pairing, where the gap changes sign across the nesting vector.     

Relation of gas permeability with structure of aromatic polyimides II

We investigated relations between diffusivities on polyimides and physical parameters with mobilities of segments and examined viscoelasticity of polyimides on introducing the parameter as an index of mobilities of polymer chains.     

Thermal behavior of poly(bisphenol A carbonate) in the presence of phosphorus compounds

To clarify the interaction between poly(bisphenol A carbonate) (PBAC) and phosphorus compounds such as triphenylphosphine oxide (TPPO), triphenyl phosphate (TPP), and resorcinol bis(diphenyl phosphate) (RDP), PBAC was heated in the presence of these phosphorus compounds at 240 °C for 2 h, and the resulting polymers were analyzed by ¹H NMR spectroscopy and gel permeation chromatography. When heated in the presence of TPPO, the PBAC sample decomposed extensively, resulting in a substantial decrease in molecular weight. On the other hand, thermal treatment in the presence of the phosphates increased the molecular weight. In both cases the molecular weight distribution became narrower. Thermal treatment of PBAC in the presence of both TPPO and TPP allowed us to control the molecular weight with a narrower distribution. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1069–1074, 2004     

Application of an electrochemical membrane reactor to the thermochemical water splitting IS process for hydrogen production

The Bunsen reaction (SO₂ + I₂ + 2H₂O = H₂SO₄ + 2HI) in the thermochemical IS process to produce hydrogen was successfully employed using an electrochemical membrane reactor. H₂SO₄ and HI were concentrated in the anode side and the cathode side of the reactor, respectively. I₂ is the dominant bulk of the recycling chemicals in this process, and I₂ concentration at the outlet of the reactor was reduced ca. 93% by using this technique. The electric energy consumption for the reaction was about 50% smaller by reducing the concentration of I₂ indicating that the IS process can be operate efficiently at low I₂ concentration. The reaction was carried out for 4 h, and the HI concentration was increased by 26%. This amount was the same within 10% as the values calculated from the total loaded electricity. In order to decrease the overpotential at the anode side, small amount of HI was added to the anode side solution. The total voltage was reduced by 0.03 V by the addition of HI.     

Ion-exclusion chromatography of aliphatic car☐ylic acids on a cation-exchange resin by elution with polyvinyl alcohol

Ion-exclusion chromatography of aliphatic car☐ylic acids of different acidity (pK_a) and hydrophobicity was investigated on a polystyrene-divinylbenzene (PS-DVB) based strongly acidic cation-exchange resin in the H⁺ form and conductivity detection by elution with polyvinyl alcohol (PVA). When water was used as an eluent, the resolution of the car☐ylic acids was very low and the peak accompanied a fronting depending on their hydrophobicities. Therefore, to improve the peak shape and the peak resolution, aqueous eluents containing PVAs (degrees of polymerization, n=500, 1500and2000) with many OH groups were tested for the ion-exclusion chromatographic separation of the car☐ylic acids. When aqueous eluents containing PVA were used, the fronting was decreased dramatically by the effect of increased hydrophilicity of the PS-DVB cation-exchange resin surface due to adsorption of OH group in PVA. The high resolution ion-exclusion chromatographic separation without the fronting and highly sensitive conductimetric detection of the car☐ylic acids was accomplished successfully by elution with a 0.2% PVA (n=1500)-10% methanol-water.