We attempted to fabricate and evaluate a new nitrogen oxides (NO_x) decomposition electrochemical cell with the additional NO_x adsorbent and investigated a cell operating method to achieve a low temperature operation in the presence of excess O₂. To clarify the arrangement that improves the effect of NO_x absorbent on NO_x decomposition property at low temperature range, we carried out the NO_x decomposition measurements on three kinds of electrochemical cells. As a result, NO_x absorbent have drastically improved the NO gas decomposition properties though the current values of each cell were almost the same. The NO gas decomposition by a GDC (10 mol % Gd doped CeO₂) based cell with the NO_x adsorbent took onset around 225°C. Highly effective NO gas decomposition at a low temperature range (<300°C) has been possible by using the electrochemical cell which saturated aqueous solution of KNO₃ penetrated into the catalytic layer electrodes after the cell operation. It was clarified that the frequency characteristic was different depending on the cell-operating mode of applied AC voltage.

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Thermal transformations in ceramic products at high temperatures were studied for admixture of Cretaceous and Mio-Pliocene clays, either carbonatic or with plastic behaviour, used for Lab-tiles and factory biscuits with amounts (25%) of quartz-sand added as temper. Clay admixtures contained illites, smectites series, interstratified I/S species and kaolinite. Firing steps of pastes in the factory took place in a tunneled gas kiln at 1080°C; whereas, tiles used for laboratory experiments were fired in an electric kiln (600–1050°C). SEM and XRD patterns help identify minerals disseminated in a glassy matrix as well as idiomorphic crystals formed in pored ceramic tiles, including feldspars (anorthite, sanidine), wollastonite, diopside and melilite (gehlenite). In the fired products, minerals form preferably in pores and crystal genesis is mainly controlled by melt flow. Wollastonite, diopside and gehlenite appear at 800°C. Gehlenite amounts remain nearly constant or may diminish slightly above 1000°C. Enough calcite amounts favor formation of anorthite, gehlenite and wollastonite; whereas gehlenite doesn’t appear necessarily as a precursor for anorthite. It is worthy of noting that gehlenite persists at 1100°C and coexists with anorthite. The later crystallizes above 850°C and its amounts increase abruptly above 1000°C. Following mineral crystallization at elevated temperature, the melt precursor can be either completely consumed or remains as relicts in biscuits.

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Porous spherical granules of β-tricalcium phosphate (β-TCP) composed of rod-shaped particles were prepared via a hydrothermal route. The biological significance of implantation of the spherical β-TCP granules for healing of bone defects was analyzed by implantation into 2 mm diameter and 3 mm deep defects created in tibiae of 9-week-old Wistar rats. Implantation of spherical β-TCP contributed to regeneration of bone tissue. At 2 and 4 weeks after implantation, numerous alkaline phosphatase-positive cells appeared around the implant and newly formed bone. At 8 weeks after implantation, residual implants were mostly embedded in bone tissue. Without implantation, bone defects healed with a much lower amount of bone. In addition, bone marrow adipocytes were considerably fewer in tibiae with implants compared to tibiae without implants at 4 and 8 weeks after the operation. These data suggested that implanted β-TCP granules worked as scaffolds to maintain alkaline phosphatase-positive cells and also resulted in less fatty change of bone marrow.

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We have investigated the multi color density photochromism in reduced tridymite BaMgSiO₄ (BMS-H) semiconductors, which can utilize green light, blue light, sunlight and ultraviolet light. It is found that BMS-H is one of visible light photochromic material with high response. BMS-H changes color from white to pink by sunlight irradiation or 405 nm light. The colored BMS-H is irradiated with 532 nm light, and the sample is substantially bleached. Furthermore, the colored BMS-H changes bright pink by 365 nm light irradiation. The pink color density of BMS-H strongly depends on the wavelength of irradiation lights. After heat treatment of 250°C for three minute in air, the sample is substantially bleached, and the bleached sample regains its color on light irradiation. BMS-H shows high reversibility in the coloring–bleaching processes. The pink color of BMS-H irradiated 365 nm light could be observed by visual confirmation after 22 days. The photogenerated colored state is comparatively stable in air at room temperature.

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The load dependence of densification during a Vickers indentation test was investigated for three commercial glass compositions, soda-lime silicate glass, aluminoborosilicate glass, and lead borosilicate glass, each of which exhibits markedly different susceptibility to crack initiation. The contribution of densification to the total deformation due to indentation was evaluated as the ratio of the depths of indentation before and after heat treatment measured with an atomic force microscope (AFM). For the soda-lime silicate and aluminoborosilicate glasses, the contribution of densification decreases with increasing applied load, but the rate of the decrease is less for the alumonoborosilicate glass than for the soda-lime silicate glass. For the lead borosilicate glass, the contribution of densification is low throughout the range of loads investigated. The residual stress can be estimated from the contribution of densification, and the variation of load dependence of the residual stress is considered to result in a large difference in the crack initiation load among the glasses.

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A flow-micro-reactor system was employed to fabricate hydroxyapatite (HAp) in order to mimic the interface between calcium and phosphate solutions on a wet chemical procedure. The mixing ratio of calcium nitrate tetrahydrate and diammonium hydrogenphosphate solution was set to the stoichiometric atomic ratio HAp, 1.67, while pH value of the product suspension was varied from 6.4 to 10.0. The product morphology was changed from nano-sheet type to nano-particle type via nano-rod one, while their size was decreased from 100–500 nm to 50 nm. All as-prepared samples, irrespective of pH value of the resultant suspension, consisted of HAp, predominant phase, octacalcium phosphate (OCP), and dicalcium phosphate dihydrate (DCPD) or dicalcium phosphate anhydrate (DCPA). A batch system using the same solutions yielded very similar results, which confirmed that the reactions in this micro-reactor well reproduced a large-scale mixing system. Calcining sample obtained from pH 6.4 suspension for 2 h at lower temperatures (<400°C) lead to decomposition of DCPD, DCPA, and OCP. Trace tricalcium phosphate (TCP) appeared on calcination above 400°C. HAp remained the predominant phase throughout the process. After calcination at 600°C, no other phases than HAp and TCP were present in the product. The analyzed ratio Ca/P (1.38) implied that those crystalline phases were highly Ca-deficient, and that amorphous calcium phosphates were involved in both as-prepared and calcined sample pH 6.4.

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The adhesion of human erythrocytes settled for different times (15, 30 and 45 min) onto opaque zirconia surfaces of different surface roughness (R_a 0.08, 0.8 and 1.0 µm) was investigated with detachment experiments. The parallel plate/laminar flow experimental set up was employed, whereby the cells were subjected to increasing shear stress, applied via controlled flow of phosphate buffer solution (PBS), and gradually detached. The experimental results showed that the critical shear stress, τ_s,c, corresponding to 50% detachment, was about 15 dyn/cm². The distribution curves of attachment suggested that smoother surfaces and longer settling times favoured strengthening of cells adherence, but the influence of settling time was sounder in smoother than in rougher surfaces. Assuming that the cells’ shape relaxes over prolonged settling time, a geometric model, providing satisfactory interpretation of the experimental results, is consistent with the prediction that the surface morphology precisely determines the maximum extent of erythrocyte/surface contacting area and consequently the adhesion strength.

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In this study, carbon nanotubes were formed from camphor oil decomposition on Fe/Ni/Mg catalysts at 650°C by fluidized floating catalyst method. X-ray diffraction (XRD) was used to examine the characteristics of carbon nanotubes. The carbon nanotubes were also examined both by FESEM and Raman spectroscopy to define their appearance and structure which revealed that dense bundle of mixed multi-walled and single-walled carbon nanotubes. The diameters of the single-walled carbon nanotubes were estimated to be around 0.86–2.31 nm. Little amount of carbon nanotubes were found on the Fe/Ni/Mg catalyst surface at 550°C; while a significant amount of carbon nanotubes were observed at 650°C. According to the XRD spectrum, there was carbon and graphite present in the deposited samples. Raman spectroscopy revealed two peaks at 1347–1357 cm⁻¹ (D band, disorder mode, amorphous carbon) and 1572 cm⁻¹ (G band, graphite sp² structure). FESEM results indicated the Fe/Ni/Mg could catalyze the camphor oil decomposition to form carbon nanotubes even at a lower temperature.

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Fully dense nanostructured SiC ceramics were fabricated by spark plasma sintering of nanosized β-SiC powder with 40 nm in diameter through liquid-phase sintering at the total content of 10 vol % of sintering additives composed of 95 mol % AlN and 5 mol % Y₂O₃. The dense SiC ceramics sintered at 1900°C for 300 s consisted of equiaxed grains with the mean grain size of 70 nm without significant grain growth during the sintering. The full densification (>99% of theoretical) of the nanosized β-SiC powder was achieved at more than 5 vol % of the AlN–Y₂O₃ additive. The grain size decreased with increasing total amount of AlN–Y₂O₃ additive and decreasing holding time at 1900°C.

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We studied the effects of residual pores on the transparency of cubic zirconia ceramics by applying Mie scattering theory. The optical haze value H, defined as the diffuse transmission divided by the total forward transmission, was calculated as a function of the pore size (r_pore) and the porosity of residual pores (V_pore) with sample thickness (t) = 1 mm. Even a small amount of pores critically affect the transparency; V_pore < 5 ppm is required to maintain H value within 1%, when r_pore = 0.05 µm is assumed. The theoretical study also revealed that the acceptable amount of residual pores for H = 1% gradually degreases with an increase in the refractive index of the materials.

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A facile processing strategy based on a simple pressing and heat-treatment at 800°C in air or argon was successfully demonstrated for fabricating encapsulated ZnO in porous polysiloxane-derived ceramic matrix. The composite samples contain ZnO crystallites with wurtzite structure embedded in amorphous SiO₂ or SiOC matrix and have 51–58% porosity depending on the starting polysiloxane content and heat-treatment atmosphere. For the samples heat-treated in air, the one with more ZnO content in the batch composition showed higher green-emission intensity as well as lower excitonic-emission intensity in photoluminescence (PL) spectrum compared to the one with less ZnO content. The result can be understood in terms of the amount of defects such as oxygen vacancies in the ZnO crystallites: the former has higher defect density than the latter. Raman spectra for the two samples support the interpretation. The samples heat-treated in argon exhibit weaker PL strength compared to the air-treated ones in the whole photon-energy range, attributable to the secondary phase (ZnSiO₃) formation.

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Several studies have demonstrated the use of biomimetic approaches in the synthesis of a variety of inorganic materials. In this study, a low-temperature and natural pH procedure for the synthesis of silica was developed using hydrolytic enzymes. For the preparation of silica particles at room temperature and pH 7, a screening test for enzyme-catalyzing direct hydrolysis and polycondensation of tetraethoxysilane by using 5 types of hydrolases; pepsin, trypsin, esterase, and two lipases were chosen as biocatalysts; moreover, these enzymes can promote the precipitation of silica within 3 days. The ²⁹Si nuclear magnetic resonance (NMR) measurements indicated that the enzyme activity in ionic liquids was higher than that in aqueous buffer solutions, and that the obtained silica particles were highly polycondensed. Under ionic liquid conditions, it was observed that enzymes were effectively encapsulated in the sol–gel silica material. In addition, for siloxane bond formation the catalytic activity of silica–enzyme composites was higher than that of free solution enzymes.

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Recently, the number of published papers on the sintering technologies activated by current have increased exponentially. In particular, it has been reported that the application of electric field as high as 120 V/cm permitted the instantaneous full densification of yttria stabilized tetragonal zirconia at the unusual low temperature of 850°C. The mechanisms of the so called flash sintering phenomenon are elucidated by analyzing the temperature distribution of the bulk sample under the application of the electric field.

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