Novel strategies for regenerating or reconstructing damaged bone tissues are of urgent necessity, because of limitations in conventional therapies for trauma, congenital defects, cancer, and other bone diseases. The tissue engineering approach to repair and regeneration is founded upon the use of biodegradable polymer scaffolds, which may manipulate bone cell functions, encourage the migration of bone cells from border areas to the defect site, and provide a source of inductive factors to support bone cell differentiation. During the past decades, scaffolds from natural biodegradable polymers such as collagen, gelatin, fibrin, and alginates, or synthetic biodegradable polymers such as polyglycolide, polylactides, and copolymers of glycolide with lactides have been extensively explored. On the other hand, it has been confirmed that the bonelike apatite layer, deposited spontaneously on the biomaterial surfaces, can enhance osteoconductivity. The presence of such bone-like apatite layers is also believed to be a prerequisite to conduction of osteogenic cells into various porous scaffolds or onto the surface of bioactive glasses. The formation of such bone-like apatite is favored by the cooperative behavior of a hydrated silica or titania gel surface Si–OH or Ti–OH groups as well as calcium ions to be released into the body fluid when implanted. Thus, hybrid materials derived from the integration of biodegradable polymers with bioactive inorganic species may construct a new group of scaffolds appropriate for tissue engineering. Moreover, tissue engineering approach depends on the use of porous scaffolds that serve to support and reinforce the regenerating tissue. Controlled porous structures of these scaffolds allow cell attachment, and migration, tissue generation, or vascularization. The synthesis of novel chitosan-silicate hybrids derived from the integration of chitosan and γ-glycidoxypropyltrimethoxysilane (GPTMS) has been studied. Some of the results on this hybrid for biomedical application are introduced.

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In this study, carbon nanofibers (CNFs) having different amounts of defect were prepared by acid-treating for 0.5, 1 and 5 h and were combined with alumina. Then, the influence of the amount of defect on the CNFs on microstructure development of the CNFs/alumina composites and relationship between the fracture toughness and the average alumina grain size was investigated. The intensity ratio of D-band to G-band (D/G) in Raman spectra of the CNFs increased from 0.34 for pristine CNFs to 0.95 for the CNFs acid-treated for 5 h with the acid-treatment time, which indicates that the amount of defect on the CNFs increased with the acid-treatment time. The alumina grain growth in the dense composites sintered at 1200–1300°C was not influenced by the amount of defect on the CNFs, however, the composite containing CNFs having the moderate amount of defect (D/G = 0.56) showed the slowest alumina grain growth rate at 1350–1450°C. The fracture toughness of the composites containing the CNFs acid-treated for 0.5 h increased with a decrease in average alumina grain size and reached 5.6 MPa·m^0.5 at the average alumina grain size of 0.84 µm, which was 60% higher value compared to monolithic alumina (3.5 MPa·m^0.5). However, fracture toughness of the composites containing CNFs acid-treated for 1 and 5 h increased with a decrease in average alumina grain size, showed the maximum values of 5.0 and 4.5 MPa·m^0.5 at average alumina grain sizes of 1.3 and 1.6 µm, respectively, and decreased as the average alumina grain size decreased further. The maximum fracture toughness of the composite containing the CNFs acid-treated for 5 h was lower than that of the composite containing the CNFs acid-treated for 1 h.

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Hydroxyapatite (HA) ceramics have been recognized as bone substitute materials in orthopedic and dental applications because of their chemical and biological similarity to human bone. Porous HA ceramics can be used as scaffold materials, if their microstructure is controlled in terms of pore size and porosity. The objective of the present work was to produce tubular-shaped HA scaffolds for biomedical applications using the cost-effective technique of electrophoretic deposition (EPD) which enables various 3D shapes to be produced. Nano HA powders were produced and mixed with multi-walled carbon nanotubes (MWCNTs) by a hydrothermal process. Calcium acetate (Ca(CH₃COO)₂), and phosphoric acid (H₃PO₄) were used as starting materials for the synthesis of the nano HA powders. Porous HA coatings were deposited on carbon rods by EPD at 60 V using a butanol suspension mixture containing nano HA powders and MWCNTs. Nano composite coatings produced were sintered at 1200°C for 60 min to burn-out the carbon rod and MWCNTs. It was shown that MWCNTs provided crack-free coating layers after coating and a porous structure after sintering. The porous HA coatings obtained were coated using different EPD parameters in terms of applied voltage and deposition time. EPD provides a coating thickness of ~310 µm for a deposition time of 480 s. This method enabled the formation of coatings with variable thickness, depending on the duration of coating and applied DC voltage. Hydrothermal mixing of HA/MWCNTs and the mechanism of deposition are also discussed. The methods can produce 3D-shaped HA scaffolds for clinical applications. The results demonstrate that the HA tubes obtained are candidate materials as scaffolds for bone repairing and generation.

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Mullite-SiC composite refractories were prepared using mullite, α-SiC, Si and Al₂O₃ as starting materials via carbonization reaction sintering by buried in coarse coal particles. The phase composition and mechanical properties of the composite refractories were studied. Results showed that main phases in the composite refractories consisted of mullite, α-SiC, β-SiC and a small amount of cristobalite. Both bulk density and flexural strength of the samples increased with the increase of silicon addition. The samples prepared at 1400°C, with 12 mass % of silicon content added in the initial raw materials, had better properties compared with the other samples, with bulk density of 2.28 g/cm³, flexural strength of 32.63 MPa, and retained flexural strength of 35.92 MPa after thermal shock by 5 times water quenching from 1200°C to room temperature. The slight increasing of flexural strength after 5 times thermal shock trials is arose from the protective oxidation of α/β-SiC and the second-sintering of samples.

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Well-dispersed zinc ferrite (ZnFe₂O₄) nanoparticles were successfully prepared by a novel salt-assisted solution combustion process. The effects of types and amounts of the added salt on the properties of the products were investigated by XRD, SEM, and BET nitrogen adsorption techniques. The results indicated that the introduction of salt into reaction system facilitate the formation of well-dispersed spinel zinc ferrite and increase specific surface area of the resultants from 7.14 to 88.34 m²·g⁻¹ when KCl/M ratio is 2/3. A visible-light-active ZnFe₂O₄/TiO₂ photocatalyst was prepared by physically grinding the ZnFe₂O₄ nanoparticles with TiO₂ (P25) at ambient temperature, and it exhibited excellent photocatalytic activity for the mineralization of rhodamine B. With increasing of ZnFe₂O₄ amount from 0 to 3wt %, the activity of ZnFe₂O₄/TiO₂ composite increased. The maximum photoactivity is observed when the amount of ZnFe₂O₄ is 3 wt % and more than 97% of rhodamine B disappears after 4 h visible-light irradiation.

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Two kinds of silica sols prepared by different methods were used to investigate effects on properties of zeolite/silica sol deposits formed by the electrophoretic deposition (EPD). Hy type silica sol, prepared by hydrolysis of tetraethyl orthosilicate (TEOS) with NaOH aqueous solution, consisted of fine (<0.1 µm) and strongly agglomerative particles. These sol particles inhibited the EPD rate of this system and the silica sol content was limited up to 14.2 percent of the deposit. On the other hand, St type silica sol, prepared by hydrolysis of TEOS with NH₃ aqueous solution (Stöber’s method), was composed of mono-dispersive spherical particles with an average diameter of 0.59 µm. The St-sol enhanced the EPD rate and proportionally increased the sol content with the starting EPD composition. Both silica sols showed substantial binding strength as durable property of the zeolite/silica-sol deposits against peeling from the surface of the substrate in agitating water. The prepared zeolite/silica sol deposit using both types of silica sols showed adsorption of Pb²⁺ ions from an aqueous solution, which suggest prepared modules will be useful for removing hazardous cations from polluted solutions.

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This paper presents a new type of surface modification of titanium to promote osseointegration. A double-layer coating was designed to endow titanium with enhanced osteoconductivity; a gelatin layer, that offers an environment for the attachment of osteoblast cells, was covalently bonded to the surface of titanium, after which a calcium phosphate layer composed of octacalcium phosphate and low-crystallinity hydroxyapatite was deposited onto specimens at 310 K with the mediation of urease. Although it has been difficult to combine gelatin and calcium phosphate because there has never been an appropriate technique to do so, a newly developed technique employing urease has made possible to deposit calcium phosphate at 310 K. The calcium phosphate layer was approximately 20 to 30 µm thick and adhered well to the titanium/gelatin substrate. The gelatin/calcium phosphate layer promoted the proliferation of osteoblast-like MC3T3-E1 cells and subsequent calcification. Additionally, an implant test in GK rats suggested that the layer may enhance the formation of new bone and new blood vessels. The surface modification presented herein may be a promising technique for dental and orthopedic implants.

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La_1–xSr_xMn_0.8Cu_0.2O_3–δ (LSMCu, 0.1 ≤ x ≤ 0.4) powders were prepared using the EDTA-citrate complexing process. The synthesized LSMCu powders were a pure perovskite phase, whereas the composition with x = 0.4 has second phases. The unit cell volumes decreased with increasing Sr²⁺ content because substituted Sr ions cause an increase in Mn⁴⁺ ions, which has a smaller ionic radius than Mn³⁺. The electrical conductivity also improved with increasing Sr addition in 0.1 ≤ x ≤ 0.3, revealing a small polaron hopping mechanism. The oxidation state of Mn ions increased with the addition of Sr ions in 0.1 ≤ x ≤ 0.3 but the oxidation state of Cu ions was unchanged in 0.1 ≤ x ≤ 0.3. The addition of Sr ions in the A-site of LSMCu can lead to a contraction of the lattice volume because of the decreased Mn–O bond length and increased Mn⁴⁺ ions, which can enhance the electrical conductivity.

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Browning after heating under vacuum has been studied on bismuth borate glasses. It was found that the reaction of water with glass surfaces was a necessary step for browning and that browning occurred at the surface of glass. The fraction of Bi atoms forming Bi metal was about 1%. It was deduced that browning was caused by the formation of Bi metal particles through the dehydration of hydrated layer of the glass surface.

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We have synthesized several kinds of porous carbon material by template method using 2 kinds of natural allophanic soil purchased in Japan as template materials. To determine the hydroscopic properties of the templated porous carbon specimens, we measured their water adsorption and desorption isotherms around room temperature (283, 293 and 298 K). We also measured porous and chemical properties of the templated porous carbon specimens, and investigated the relationships between pore development and their water isotherms. The features of the isotherm curves of the templated porous carbon specimens were different from those of common activated carbon used as a reference, and the features in this study were dependent on template materials rather than carbon ingredients. Some of the templated porous carbon specimens had water adsorption isotherms that rose sharply at approximately 80% relative humidity (RH), and the desorption isotherms dropped off at 60% RH. The results indicate the possibility of application of these specimens as effective adsorbents that are not susceptible to moisture as compared with common activated carbon. The specimens are also assumed to be useful as humidity control materials.

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PbMoO₄ nanoparticles and pagodalike microcrystals have been controllably prepared by a simple sonochemical method without any surfactants. The as-prepared powders were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the pH played a crucial role on the controllable synthesis of PbMoO₄. Pagodalike microcrystals could be formed on acid condition, and nanocrystals were obtained in the case of pH 7 and pH 14. The synthesis mechanism was also discussed.

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This report discloses the electro-optic (EO) properties of a lead-free Bi_0.5(K_0.33Na_0.67)_0.5TiO₃ (33BKNT) single crystal. The 33BKNT single crystal has near zero initial birefringence at room temperature and is optically isotropic. Moreover, the temperature dependence of the crystal’s dielectric permittivity reveals its relaxor behavior. The 33BKNT single crystal shows a quadratic EO effect with an EO coefficient (Kerr coefficient) of 16 × 10⁻¹⁷ m²/V², which is higher than the Kerr coefficient in other lead-free EO materials at room temperature.

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