TiO2 synthesis inspired by biomineralization: control of morphology, crystal phase, and light-use efficiency in a single process

Hydroxyapatite is mineralized along the long axis of collagen fiber during osteogenesis. Mimicking such biomineralization has great potential to control inorganic structures and is fast becoming an important next-generation inorganic synthesis method. Inorganic matter synthesized by biomineralization can have beautiful and functional structures that cannot be created artificially. In this study, we applied biomineralization to the synthesis of the only photocatalyst in practical use today, titanium dioxide (TiO(2)). The photocatalytic activity of TiO(2) mainly relates to three properties: morphology, crystal phase, and light-use efficiency. To optimize TiO(2) morphology, we used a simple sequential peptide as an organic template. TiO(2) mineralized by a β-sheet peptide nanofiber template forms fiber-like shapes that are not observed for mineralization by peptides in the shape of random coils. To optimize TiO(2) crystal phase, we mineralized TiO(2) with the template at 400 °C to transform it into the rutile phase and at 700 °C to transform it into a mixed phase of anatase and rutile. To optimize light-use efficiency, we introduced nitrogen atoms of the peptide into the TiO(2) structure as doped elemental material during sintering. Thus, this biomineralization method enables control of inorganic morphology, crystal phase, and light-use efficiency in a single process.     

A physical approach to specifically improve the mobility of alkane liquid drops

Seamless control of resistance to liquid drop movement for polar (water) and nonpolar alkane (n-hexadecane, n-dodecane, and n-decane) probe liquids on substrate surfaces was successfully demonstrated using molten linear poly(dimethylsiloxane) (PDMS) brush films with a range of different molecular weights (MWs). The ease of movement of liquid drops critically depended on polymer chain mobility as it relates to both polymer MW and solvent swelling on these chemically- and topographically identical surfaces. Our brush films therefore displayed lower resistances to liquid drop movement with decreasing polymer MW and surface tension of probe liquid as measured by contact angle (CA) hysteresis and tilt angle measurements. Subsequently, while mobility of water drops was inferior and became worse at higher MWs, n-decane drops were found to experience little resistance to movement on these polymer brush films. Calculating CA hysteresis as Δθ(cos) = cos θ(R) - cos θ(A) (θ(A) and θ(R) are the advancing and receding CAs, respectively) rather than the standard Δθ = θ(A) - θ(R) was found to be advantageous for estimation of the actual dynamic dewetting behavior of various probe liquids on an inclined substrate.     

An alternative scheme for calculating the unrestricted Hartree–Fock equation: Application to the boron and neon atoms

We present an alternative scheme for calculating the unrestricted Hartree–Fock (HF) equation. The scheme is based on the variational method utilizing the sophisticated basis functions that include no adjustable parameters. The validity of the present scheme is confirmed by actual calculations of the boron and neon atoms. The total energy of the present scheme is lower than that of the conventional restrictive HF equation, but higher than that of the CI method. Also, the resultant wave function satisfies the electron–nucleus cusp condition.     

Strong two-photon absorption and its saturation of a self-organized dimer of an ethynylene-linked porphyrin tandem

The two-photon absorption properties of a self-organized dimer of a free-base and zinc(II) porphyrins tandem linked with an ethynylene group and terminated by imidazolyl and phenylethynyl groups were investigated. The self-organized dimer was found to exhibit strong two-photon absorption and furthermore the saturation of the two-photon absorption owing to the intense transition.     

A vapoluminescent Eu-based metallo-supramolecular polymer

An Eu-based metallo-supramolecular polymer (polyEu) was prepared by self-assembly coordination polymerization. Unique vapoluminescence property of polyEu triggered by acid-base vapor was found and a photoluminescence display in switchable imaging by acid-base vapor was fabricated.     

Molecular engineering and solvent dependence of excitation energy hopping in self-assembled porphyrin boxes

It has been demonstrated that the direction and magnitude of transition dipole moments, and hence rates in the excitation energy hopping in the self-assembled porphyrin boxes can be tuned by insertion of ethynyl groups as well as the dielectric constant of solvent.     

Structure and dynamics of water: from ambient to supercritical

Our recent works on supercritical water are reviewed. In order to elucidate the hydrogen bonding state of supercritical water, the proton chemical shift of the water proton is measured at temperatures up to 400 °C and densities of 0.19, 0.29, 0.41, 0.49, and 0.60 g/cm³. The magnetic susceptibility correction is made in order to express the chemical shift relative to an isolated water molecule in dilute gas. The chemical shift is then related to the average number of hydrogen bonds in which a water molecule is involved. It is found that the hydrogen bonding persists at supercritical temperatures and that the average number of hydrogen bonds is at least one for a water molecule at the densities larger than the critical. The density dependence of the chemical shift at supercritical temperatures is analyzed on the basis of statistical thermodynamics. It is shown that the hydrogen bonding is spatially more inhomogeneous at lower densities. The dipole moment of water at supercritical states is also estimated from the number of hydrogen bonds. The dynamical counterpart of our structural study of supercritical water has been performed by NMR relaxation measurements. Using D₂O, we measured the spin-lattice relaxation time and determined the reorientational relaxation time as a function of the water density and temperature. It is then found that while the reorientational relaxation time decreases rapidly with the temperature in the subcritical condition, it is a weak function of the density in the supercritical conditions.     

Constituents of crinoidea. 2. Isolation and structure of the novel type gangliosides from the feather star Comanthus japonica.

Two novel type gangliosides CJP2 and CJP3 have been obtained from the feather star Comanthus japonica. On the basis of methylation linkage analysis combined with ammonolysis and other chemical and spectroscopic evidence, the chemical structures of CJP2 and CJP3 were determined to be alpha-9-O-Me-NeuGc-(2-->3)-inositolphosphoceramide and alpha-9-O-Me-NeuGc-(2-->11)-alpha-9-O-Me-NeuGc-(2-->3)-inositolphosphoceramide, respectively. These gangliosides are unique in that they are inositolphosphoceramide derivatives possessing sialic acid; such gangliosides have not previously been identified. The presence of 9-O-methyl-N-glycolyl-neuraminosyl residues is also unique in naturally occurring gangliosides.     

Precise measurement of the CP violation parameter sin2φ1 in B0→(cc¯)K0 decays

We present a precise measurement of the CP violation parameter sin2φ1 and the direct CP violation parameter A(f) using the final data sample of 772×10(6) BB[over ˉ] pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is reconstructed in a J/ψK(S)(0), ψ(2S)K(S)(0), χ(c1)K(S)(0), or J/ψK(L)(0) CP eigenstate and its flavor is identified from the decay products of the accompanying B meson. From the distribution of proper-time intervals between the two B decays, we obtain the following CP violation parameters: sin2φ1=0.667±0.023(stat)±0.012(syst) and A(f)=0.006±0.016(stat)±0.012(syst).     

Estimation of diffusion and permeability coefficients of CO2 in polymeric membranes by FTIR method

Infrared spectra of CO₂ sorbed in rubbery and glassy polymeric membranes were measured to examine the relationships between the spectroscopic data and the physical properties of the membranes. The two peaks observed in the spectra of CO₂ were attributed to the R branch and P branch of CO₂ sorbed in the membranes based on the consideration that both peaks were observed at a temperature above the glass transition temperature of the membranes. Apparent diffusion coefficients of CO₂ in the membranes were measured from the desorption kinetics of CO₂ detected by FTIR spectroscopy. The solubility coefficients of CO₂ were also estimated from absorbance spectra of CO₂ sorbed in the membranes using Lambert-Beer's rule. The permeability, solubility, and diffusion coefficients estimated by the FTIR method were found to correlate well with the coefficients obtained by conventional methods such as vacuum-pressure or sorption isotherm methods. © 1996 John Wiley & Sons, Inc.