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Porous anodic alumina are well known to be fabricated by anodic oxidation using direct current (DC). In this work, nano laminated structures of alumina were fabricated by controlling the power supply condition of alternating current (AC) oxidation. In particularly, laminated alumina with terraced cones, which are similar to spiral-shaped shells, were prepared by controlling the AC condition

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Thin film with one-dimensional oxide nanomaterials has attracted extensive interest due to their importance in basic scientific research and potential technological applications. Here, we report our bio-inspired strategies for silica/titania thin film with tunable surface nanostructure on arbitrary substrates, with the silica/titania mineralization occurring in aqueous media under room temperature with a high rate (i.e. 10 min). Linear polyethyleneimine (LPEI) shows the unique ability to self-assemble into nanostructured matrix layer on the substrates, which acts as biomimetic template to give nanotextured oxide films. Following modification of the oxides films with low-surface energy compound resulted in super-liquid-repelling silica nanosurface and photoresponsive titania nanosurface.

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Linear poly(ethyleneimine) (LPEI) is highly crystalline polymer and forms fibrous aggregates after cooling processes in hot aqueous solution, which can be used as templates for the silica deposition to afford silica replicas with the same morphology. Some additives affect the crystallization processes of LPEI to change the shape of LPEI templates, which results in variously-shaped silica corresponding to the template morphologies. In addition, the LPEI crystallization on the glass substrates and successive silica duplications lead to hierarchical silica thin films with grass-like or network structures, which are not formed in the water phases.

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[in Japanese]

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We have successfully synthesized the phosphor specimens of [Ca_0.99 Eu²⁺_0.01][Al_1-xSi_1+x]N_3-xC_x (0 ≤ x ≤ 0.6), which were prepared by adding a few SiC compound to the raw materials of CaAlSiN₃:Eu²⁺. Regent-grade chemicals of Ca₃N₂, AlN, Si₃N₄, SiC, EuN were well mixed using a mortar under nitrogen atmosphere. The mixed powder specimens were charged into BN crucibles, which was heated at 1600 °C for 2 h and subsequently at 1800 °C for 4 h under nitrogen pressure of 1 MPa. Diffuse reflectance of [Ca_0.99Eu²⁺_0.01][Al_1-xSi_1+x]N_3-xC_x was, regardless of the x-value, necessarily higher than that of CaAlSiN₃:Eu²⁺, indicating that the doping of carbon atoms into the anion sites in the crystal structure of CaAlSiN₃:Eu²⁺ effectively decreases the reabsorption of photoluminescence.

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CdSe-related quantum dots (QDs) are expected to be used for various applications. We have prepared several thin-glass coated QDs by changing their preparation conditions. When the amount of QDs is optimized, the surface is uniformly coated by glass-layer. This is related to the surface silanization of the QDs. This silanization affects the stability of the QDs, and is probably related to the size of QD assembly when they are transferred to water phase.

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Second dopant of A site such as Sr²⁺, Mg²⁺ and Zn²⁺ and that of B site such as Ti⁴⁺ and Sn⁴⁺ co-doped CaZrO₃ : Eu³⁺ were synthesized by the solid state reaction method. The XRD patterns of the synthesized samples were composed of perovskite type orthorhombic structure. Lattice constant was decreased by co-doping Mg²⁺ having larger ionic radius relative to Ca²⁺. The PL intensities were increased with the decrease of lattice constant by the Mg²⁺.

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Ca_0.6Sr_0.4TiO₃:Pr phosphor thin films were prepared by a sol-gel method on quartz glass or SrTiO3:Nb single crystalline substrates. The prepared thin films showed red photoluminescence by band gap excitation of Ca_0.6Sr_0.4TiO₃. The optical properties and electrical properties of the prepared thin films were investigated in relation to the preparation conditions for application to thin film EL devices.

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Mixed metal nitride, CaAlSiN3:Ce3+, was synthesized from an appropriate mixture of CaCN2, CaCO3, AlN, Si3N4, and CeF3 by using the carbothermal process in a N2 gas flow: 1/2 CaCN2 + 1/2(1-2x) CaCO3 + AlN + 1/3 Si3N4 + x CeF3  (Ca1-xCex)AlSiN3. The obtained phosphor indicated efficient yellow-orange emission for LED illumination and low thermal quenching effect. In addition, the saturated chromaticity coordinates also showed that resultant phosphor was possibly used as a potential candidate for the phosphor-converted white LEDs.

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A series of samples in Ca-Sr-Eu-Si-S systems has been prepared by an advanced chemical method to explore for new compounds for phosphor applications. It led us to find a new phosphor with a composition, (Ca, Sr, Eu)₃Si₂S₇. This phosphor showed a broad emission band with a maximum at 613 nm with the corresponding excitation maximum at 420 nm.

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Zinc oxide (ZnO) is known to be a widegap semiconductor exhibiting green phosphorescence. The bandgap energy can be extended by the formation of ZnO-MgO solid solution so as to blueshift visible phosphorescence. However, Mg solubility is limited to be about 4% in solid-state reaction. In this study, we prepared Zn_1-xMg_xO nanocrystals to pyrolyze Zn-Mg oxalic salts synthesized by a hydrothermal method. And here we shall report the influence of Mg doping on the crystal structure and optical properties (optical bandgap and PL).

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Direct-current (dc) inorganic EL devices were prepared with ZnO layers doped with a rare-earth (RE) as the luminescent center. The RE-ZnO layers were formed on a polycrystalline YSZ, MgO, or Al₂O₃ substrate by a dip-coating technique. The characterization indicated that the crystallinity and electric properties were strongly affected by a substrate type. The specific EL to Tm³⁺ and Eu³⁺ was observed from the dc-driven Tm-ZnO and Eu-ZnO layers, respectively.

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Effect of water on the structure and deformation of 22Na2O 11Al2O3 67SiO2 glass was investigated by molecular dynamics simulation. The hydrous glass was prepared by substituting H for Na (NH glass) and adding H2O molecules in the glass network (NMH glass). In NH glass, the water showed three patterns such as Onb-H, Ob-H, and Onb-2H. In NMH glass, there was Onb-2H bond when the glass relaxed at 300 K and Onb-H bond when the glass relaxed at 1000 K besides H2O molecule. Under compression and tension, hydrous glass deformed easily compared with anhydrous glass, due to the breakage of Si or Al-O bond by OH and H2O.

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Three dimensional atomic configurations of MgSiO₃ and Mg₂SiO₄ glasses were derived by reverse Monte Carlo simulation on the basis of diffraction data. We found that Mg₂SiO₄ glass (low glass formation ability) shows topological order in the size-distribution of rings consist of SiO₄ and MgO_x (x=4-6, 5 is major). Furthermore the RMC atomic configurations were optimized by DFT simulation and Mg-O coordination number was discussed with special attention to bond order, which can explain the discrepancy between diffraction data and NMR data.

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Basicity is a measure of electron donating ability, which is associated with electron density of a material, and it is hence expected that physical and chemical properties are correlated with atomic structure of materials through basicity. In this presentation, various studies concerning basicity which have been done in the author's research group will be introduced. The research outcomes, such as, basicity evaluation by XPS, relation between basicity and glass structure, material and process design based on basicity are shown.

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Drop calorimetry measurements were carried out between 575 and 1300 ̊C for SiO2-B2O3-Al2O3-CaO-Na2O melts. Partial molar heat capacity of B2O3 (CpB2O3) in borosilicate melts was determined by combining measured heat capacity and previously reported values of partial molar Cp for other oxides. In the Na2O bearing borosilicate melts, the CpB2O3 decreases with increasing temperature, and the decrease in CpB2O3 is enhanced by an addition of CaO or Al2O3. Large temperature dependence of the heat capacity for radioactive waste melt can be explained by the temperature and compositional variations of the CpB2O3.

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The immiscibility of melts and glasses are well-known phenomenon in various oxide systems such as silicate and borate, which are called phase separation and widely studied especially in research field of glass. This phenomenon has been applied to prepare various functional composite materials which consisted of not only two different glass phases but also the crystalline fine particles and the glass matrix. In this study, some silicate phase-separated glasses and glass ceramics were prepared by using their stable immiscibility above their liquidus temperatures. Their photocatalytic, photoluminescence, magnetic and magneto electric properties were investigated.

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To establish standard method for cell migration into porous bioceramics, we carried out round robin test of novel evaluation method for cell migration using 6 porous bioceramics including 4 practically used ones provided by manufacturers. Sample previously vacuum deaerated in cell culture medium was steadily placed on confluent cell layer and cultured for 3 and 7 days with medium change every 2 days. After the period, the sample was harvested and fixed with 2% glutaraldehyde and cut into two pieces. These pieces were stained with Giemsa staining, observed with optical microscope. Cell migration distance was measured from optical microscopic photograph. Trend of cell migration distance among samples was the same even the culture period and/or cell type was different. This method could be useful for cell migration test and could be promising method for the international standard. (This study in part was supported by METI, Japan.)

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Siloxane-containing vaterite/poly(lactic acid) composites with cotton-like structure were prepared with a modified electrospinning method. Compressing and heating treatments were performed to the cotton-like structures to control their fiber densities. MC3T3-E1 cells were seeded onto the composite materials at a density of 5.0x10⁴ cells/ml. Proliferation of the cells on the cotton-like structures was superior to that on the fibermat. The cotton-like structured composite is expected to be useful for bone tissue engineering.

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The silicon-containing apatite (Si-HAp) powders with desired Si contents (0, 0.4, 0.8, 1.6, and 2.4 mass%) were prepared via an aqueous precipitation reaction and then surface-modified with inositol phosphate (IP6) (IP6-Si-HAp). The IP6-Si-HAp cements with various Si contents were fabricated by mixing with pure water at the powder/liquid ratio of 1/0.4 [w/w]. In order to clarify the cytotoxicity of the IP6-Si-HAP cements, MC3T3-E1 cells as a model of osteoblalst were seeded on the cement specimens. The numbers of cells cultured on the IP6-Si-HAp cements were more than those on pure HAp cement without silicon. Especially, the IP6-Si-HAp cement with the Si content of 2.4 mass% showed excellent cell proliferation among examined specimens.

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The biological efficacy of a double-layer coating of gelatin and calcium phosphate (g/CaP coating) was evaluated by means of MC3T3-E1 culture tests and animal implantation tests. The cell culture tests revealed a considerable extent of calcification on g/CaP coatings while almost no calcification on highly-crystalline HA coatings. When the g/CaP-coated titanium was implanted in the cranial bone defects in GK rats, new bone formation was observed in contact with the implant. On the other hand, the control specimens were surrounded with fibrous tissue. The g/CaP coating promoted bone formation and osseointegration within a short time period even in diabetic rats.

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Fluorescence imaging in the near-infrared (NIR) region allows acquisition of deeper and clearer images in vivo, because light scattering and absorption are minimal and tissue autofluorescence is diminished. We synthesized NIR fluorescent ring-shaped silica nanoparticles with a high tetrakis(4-carboxyphenyl)porphyrin (TCPP) content, or silica/TCPP hybrid nanorings (HNRs), by means of the one-pot sol-gel reaction using a TCPP-binding silica precursor for tumor imaging. The HNRs were functionalized with amino groups and were therefore easily modified with PEG. The PEG-modified HNRs accumulated in tumor locally over 6 h after intravenous injection and enabled clear detection of the tumor.

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External fixation pins with a fibroblast growth factor (FGF)-2-apatite composite layer (Ap-FGF pins) contribute to reduce pin-tract infection rate. So, a translational research for the Ap-FGF pins was carried out. Preparation and quality control methods of Ap-FGF pins were summarized as protocols in consideration of good manufacturers practice (GMP). According to the protocols, Ap-FGF pins conforming to a standard can be prepared successfully. The phase I/IIa clinical study of the Ap-FGF pins was approved by ethical committees in both university of Tsukuba and AIST, and has just started from December, 2011.

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Ceramic biomaterials are widely used for biomedical applications, such as artificial bone due to their biological affinity to living bone. Fundamental understanding of the reaction between ceramics and simulated body fluid leads to development of highly functionalized biomaterials through techniques implying surface modification of titanium metals for providing bioactivity, synthesis of bioactive organic-inorganic hybrids, biomimetic synthesis of composites, and fabrication of calcium phosphates with designed microstructure through hydrothermal and gel-mediated methods.

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