The ordered structures in different doping levels (x = 0.1, 0.15, 0.2, 0.25, 0.3) of yttrium doped ceria (YDC, Ce(1−x)YxO2−δ) electrolytes were investigated by electron diffraction, high-resolution transmission electron microscopy (TEM), scanning TEM, and electron energy loss spectroscopy. Oxygen vacancy ordering was experimentally confirmed within the ordered structures. With increasing the doping level, the concentration of trivalent Ce cations was increased in YDC samples and such trivalent Ce cations were supposed to mainly exist in the ordered structures. Based on our electron microscopic observation and microanalysis, a crystal model for the ordered structures is proposed.

We performed pollen analysis and accelerator mass spectrometry (AMS) radiocarbon dating on cored sediments (KS0412-3) from Kashibaru Marsh, located in the western part of the Sefuri Mountains in northern Kyushu, southwestern Japan, to investigate environmental change around the marsh. Sediment accumulation began in this marsh around cal AD 1200 and continued with an estimated average sedimentation rate of about 4 mm/yr. Human rice cultivation at this location began around cal AD 1300 and was abandoned due to the deposition of a thick sand layer at around cal AD 1400. Since this event, the area has been maintained as a “natural” marsh.

Microstructural evolution in a CeO2-Gd2O3 system at atomic and nanoscale levels with increasing Gd concentration has been comprehensively investigated by transmission electron microscopy. When the Gd concentration was increased from 10 to 80 at.%, the phase transformation from ceria with fluorite structure to solid solution with C-type structure was not a sudden change but an evolution in the sequence of clusters, domains, and precipitates with C-type structure in the fluorite-structured matrix. Moreover, the ordering of aggregated Gd cations and oxygen vacancies in these microstructural inhomogeneities developed continuously with increasing Gd concentration. This microstructural evolution can be further described based on the development of defect clusters containing Gd cations and oxygen vacancies.

Nanosized incubational domain was observed in 10 at.% gadolinium-doped ceria (GDC) using high-resolution transmission electron microscopy. Dislocations were extensively observed in 10 at.% GDC instead of heavily doped 25 at.% GDC. By Fast Fourier Transform and Inverse Fast Fourier Transform analysis, it was noticed that the incubational domain existing in 10 at.% GDC has different lattice spacing and orientation from the neighboring ceria matrix. Furthermore, dislocations were usually observed in the interface region between the incubational domain and the ceria matrix. Based on experimental results, the formation mechanism of dislocation associated incubational domain in lightly gadolinium-doped ceria is rationalized.

YB22C2N is one of a series of rare earth borocarbonitrides and is potentially the long awaited n-type counterpart to boron carbide. We conducted studies on YB22C2N spark plasma sintered with additions of YB4 and YB25C, including the investigations of the densification process and the thermoelectric properties of the material. We discovered that a small amount of dopants can lower the starting temperature of densification during spark plasma sintering (SPS). Variations of pressure and temperature during the sintering process are also found to have an effect. Electrical conductivity of the dense samples has increased due to insertion of metal borides and also because of the improvement of the relative density. At the same time, only a slight reduction was observed for the Seebeck coefficient leading to an important improvement of power factor. The highest density of more than 95% was achieved with 5 wt% of YB25(C) dopant.

A platinum (Pt) on pure ceria (CeO2) supported by carbon black (CB) anode was synthesized using a combined process of precipitation and coimpregnation methods. The electrochemical activity of methanol oxidation reaction on synthesized Pt-CeO2/CB anodes was investigated by cyclic voltammetry and chronoamperometry experimentation. To improve the anode property on Pt-CeO2/CB, the influence of particle morphology and particle size on anode properties was examined. The morphology and particle size of the pure CeO2 particles could be controlled by changing the preparation conditions. The anode properties (i.e., peak current density and onset potential for methanol oxidation) were improved by using nanosize CeO2 particles. This indicates that a larger surface area and higher activity on the surface of CeO2 improve the anode properties. The influence of particle morphology of CeO2 on anode properties was not very large. The onset potential for methanol oxidation reaction on Pt-CeO2/CB, which consisted of CeO2 with a high surface area, was shifted to a lower potential compared with that on the anodes, which consisted of CeO2 with a low surface area. The onset potential on Pt-CeO2/CB at 60 °C became similar to that on the commercially available Pt-Ru/carbon anode. We suggest that the rate-determining steps of the methanol oxidation reaction on Pt-CeO2/CB and commercially available Pt-Ru/carbon anodes are different, which accounts for the difference in performance. In the reaction mechanism on Pt-CeO2/CB, we conclude that the released oxygen species from the surface of CeO2 particles contribute to oxidation of adsorbed CO species on the Pt surface. This suggests that the anode performance of the Pt-CeO2/CB anode would lead to improvements in the operation of direct methanol fuel cells at 80 °C by the enhancement of diffusion of oxygen species created from the surface of nanosized CeO2 particles. Therefore, we conclude that fabrication of nanosized CeO2 with a high surface area is a key factor for development of a high-quality Pt-CeO2/CB anode in direct methanol fuel cells.

Objectives: We have compared mortality and risk factors for late deaths in patients with tetralogy of Fallot undergoing surgical repair in 1972 and 1982 in a Japanese multicentric study, examining in particular the impact of time of repair. Background: There is limited information on the effect that time of repair, and our constantly changing approach to it, has on late outcome in repaired tetralogy of Fallot. Methods: We analysed the Japanese registry of deaths occurring after surgical repair of tetralogy of Fallot. We studied two postoperative 1-year cohorts of survivors of surgery performed in 12 centers. Of the patients, 122, aged 29 ± 12 years, had undergone repair in 1972, their age at repair being 9.6 years. An additional 186 patients, aged 23 ± 8.7 years, had been repaired in 1982 at the age of 7.7 years. Results: Annual mortality, as judged per 100,000 population of patients with tetralogy of Fallot, declined from 0.387 in 1972 to 0.196 in 1982. Significant differences were deaths following surgery (27% vs. 13%, p < 0.001), patching of the subpulmonary outflow tract (48% vs. 89%, p < 0.001), and transjunctional patching (13% vs. 63%, p < 0.001). Late death was observed in 6 vs. 3 patients (9/308, 2.9%). The actuarial rate of survival calculated over 14 years was 97% vs. 98%. Reoperation was performed in 5 vs. 9 patients (14/308, 4.5%). Risk factors for late death were age at repair (p = 0.01), and history of reoperation (p < 0.001). Transjunctional patching (p = 0.01) proved to be associated with late mortality only in patients repaired in 1972. Conclusions: Late survival was excellent, with a low incidence of reoperations in both groups of patients. The era of repair has a big influence on total and operative mortality, but has only a small impact on late mortality. Ongoing analysis of follow-up will possibly reveal subsequent changes with time.

High-energy protons are generated by focusing an ultrashort pulsed high intensity laser at the Advanced Photon Research Center, JAERI-Kansai onto thin (thickness <10 μm) Tantalum targets. The laser intensities are about 4 × 1018 W/cm2. The prepulse level of the laser pulse is measured with combination of a PIN photo diode and a cross correlator and is less than 10−6. A quarter-wave plate is installed into the laser beam line to create circularly polarized pulses. Collimated high energy protons are observed with CH coated Tantalum targets irradiated with the circularly polarized laser pulses. The beam divergence of the generated proton beam is measured with a CR-39 track detector and is about 6 mrad.

The photoluminescence (PL) and PL excitation spectra of the single-crystal samples of yttria-stabilized zirconia (YSZ) were measured. We found that the PL spectra of two samples for the 280-nm excitation significantly differ from one another in intensity, although the two samples have the same macrostructure and the same chemical composition. These results indicate that PL spectroscopy is a useful method for studying the microstructure of YSZ. The result of the trace-impurity analysis suggests that the large difference in PL intensity between the two samples can be explained by considering the influence of Nb in the YSZ sample. It seems that Nb in YSZ caused an yttria-associated defect. The broad emission band around 550 nm would be attributed to this defect. These results suggest that information can be obtained from its PL measurement not only on the yttria-associated defect, but also on the trace impurity in the YSZ.

A basic sulfate precursor [Sc(OH)SO4·2H2O] for well-sinterable Sc2O3 powders was precipitated from mixed solutions of scandium nitrate [Sc(NO3)3] and ammonium sulfate [(NH4)2SO4] at room temperature and which was subsequently converted to Sc2O3 via dehydroxylization and desulfurization at temperatures ≥900 °C. With the reactive powders synthesized in this work, polycrystalline Sc2O3 ceramics showing high inline transmittances of approximately 70% in the visible wavelength region (corresponding to ∼90% of the theoretical value of single crystals) have been fabricated via vacuum sintering at a relatively low temperature of 1700 °C.

Scandia (Sc2O3) is a ceramic material that shows interesting thermal and optical properties, but is difficult to grow as single crystals. As an alternative, in this work we fabricated polycrystalline Sc2O3 transparent ceramics via vacuum sintering, using powders thermally pyrolyzed at 1200 °C from a scandium sulfate salt, Sc2(SO4)3 · 7.8H2O, that we prepared. Characterization of the powders was achieved by differential thermal analysis/thermogravimetry, x-ray diffractometry, Brunauer–Emmett–Teller analysis, and field-emission scanning electron microscopy. Sintering behaviors of the Sc2O3 powders were studied in air via dilatometry. The sulfate salt transforms to oxide at temperatures ≥1000 °C, and the best pyrolysis temperature for transparent ceramics fabrication is 1200 °C, at which the resultant Sc2O3 powder is good in dispersion, ultrafine in particle size (∼80 nm), and almost free from residual sulfur. Transparent ceramics were fabricated from this powder via vacuum sintering at 1625 °C or above. The ceramics sintered at 1700 °C for 4 h exhibit an in-line transmittance of approximately 56–58% in the visible light region at a sample thickness of 1.0 mm.

Surface properties and photocatalytic oxidation reactions on the hollandite-type compound K2Ga2Sn6O16 (KGSO) were examined for photoinduced hydrophilicity and oxidative decomposition of an endocrine-disrupting chemical, pentachlorophenol (C6Cl5OH, PCP), under ultraviolet (UV) illumination. The thin films and mesoporous powders of hollandite were used for examination of surface properties and photocatalysis, respectively. The photoinduced surface property was examined by measurement of the contact angle of water, ortho-chlorophenol (o-C6H4ClOH), and toluene on the surface of KGSO. The contact angle of H2O and o-C6H4ClOH decreased to 0° under UV illumination. The toluene showed little change in contact angle under UV irradiation. It is concluded that the surface of KGSO shows photoinduced hydrophilicity for H2O and aromatic compounds with hydroxyl groups (−OH). In addition, KGSO clearly showed a photo-oxidative decomposition of PCP under weak UV illumination at room temperature. The decomposition speed of C6Cl5OH on KGSO was much faster than that on previous reported nano-sized SnO2 photocatalysts. It is expected that photo-oxidative decomposition of aromatic compound will be controlled by a combination of optimum composition of the hollandite phase and control of the morphology of the hollandite particles. This suggests that hollandite would be a promising photocatalyst for decomposition of aromatic compounds in endocrine-disrupting chemicals.

Monodispersed Sc2O3 precursor particles were synthesized by the urea-based homogeneous precipitation method, with an investigation into the effects of supporting anions (NO3−, Cl−, and SO4 2−) on powder properties. Characterizations of the powders were achieved by elemental analysis, x-ray diffractometry, Fourier transform infrared, differential thermal analysis/thermogravimetry, high-resolution scanning electron microscopy, and the Brunauer-Emmett-Teller method. Unlike other rare earths, Sc3+ does not precipitate as basic carbonate but instead forms hydrated γ-ScOOH from either nitrate or chloride solution. Particles of the hydrated γ-ScOOH are pumpkin-shaped (approximately 1.0 μm) and are made up of thin-platelike crystallites emanating from a common axis. The presence of complexing SO42− changes the reaction chemistry toward Sc2O3 powders, leading to basic sulfate [Sc(OH)1.6(SO4)0.7 η H2O] precursor particles having hexagonal morphology (approximately 10 μm in diameter and 0.5 μm in thickness). The hydrated γ-ScOOH directly converts to Sc2O3 by calcination at 400 °C or above, while the basic sulfate transforms to oxide at temperatures ≥ 900 °C via an amorphous state and a Sc2(SO4)3 intermediate. The effect of SO42− on powder morphologies and reaction chemistry is discussed. Nanocrystalline Sc2O3 powders comprising monodispersed particles were obtained via thermal decomposition of the precursors.

A carbonate coprecipitation method was used for the facile synthesis of highly reactive 10 mol%-Y2O3-doped CeO2 (20YDC) nanopowders, employing nitrates as the starting salts and ammonium hydrogen carbonate (AHC) as the precipitant. The AHC/RE3+ (RE = Ce + Y) molar ratio (R) and the reaction temperature (T) significantly affect the final yield and precursor properties, including chemical composition and particle morphology. Suitable processing conditions are T = 60 °C and R = 2.5 to 10, under which precipitation is complete, and the resultant precursors show ultrafine particle size, spherical particle shape, and good dispersion. The thus-processed precursors are basic carbonates with an approximate formula of Ce0.8Y0.2(OH)CO3 · 2H2O, which directly yield oxide solid solutions upon thermal decomposition at a very low temperature of approximately 400 °C. The 20YDC solid-solution powders calcined at 700 °C show excellent reactivity and were densified to >99% of theoretical via pressureless sintering at a very low temperature of 950 °C for 6 h.

The influence that trace concentrations of SiO2 have on improving grain-boundary conduction via precursor scavenging using additional heat treatment at 1200 °C for 40 h before sintering was investigated. At a SiO2-impurity level (SIL) ≤160 ppm by weight, the grain-boundary resistivity (ρgb) decreased to 20% of its value, while no improvement in grain-boundary conduction was found at a SIL ≥ 310 ppm. The correlation between the resistance per unit grain-boundary area, rgb, and average grain size indicated that the inhomogeneous distribution of the siliceous phase in the sample with a SIL ≥ 310 ppm hampered the scavenging reaction.

Stoichiometric yttrium aluminate garnet (Y3Al5O12) precursors with a wide range of chemical compositions were precipitated by dripping a mixed solution of ammonium aluminum sulfate and yttrium nitrate into ammonium bicarbonate solutions. The resultant precursors were characterized by chemical analysis, infrared spectroscopy, differential thermal analysis/thermogravimetry, x-ray diffractometry, and scanning electron microscopy. The effects of reaction temperature, precipitant concentration, dripping speed of the salt solution, and the molar ratio of precipitant/total-cations on the composition, thermal behavior, and particle morphology of the resultant precursors were investigated. The precipitation conditions that yield carbonate precursors composed of ammonium dawsonite [NH4Al(OH)2CO3] and yttrium normal carbonate [Y2(CO3)3 · 3H2O] were determined.

Ammonium hydrogen carbonate was used as the precipitant to synthesize yttrium aluminate garnet (YAG) precursors from a mixed solution of aluminum and yttrium nitrates via coprecipitation. The carbonate precursor, with an approximate composition of NH4AlY0.6(CO3)1.9(OH)2 · 0.8H2O, transformed to pure YAG at 900 °C without the formation of intermediate phases. Reactive YAG powder was produced by calcining the precursor at 1100 °C. The YAG powder densified to 99.8% of the theoretical density by vacuum sintering at 1500 °C for 2 h, and the sintered body showed transparency. Less agglomeration of the precursor and good dispersity of the resultant YAG powder were responsible for the excellent sinterability.

Carbonate precursors of Y3Al5O12 (YAG) were synthesized from a mixed solution of alum and yttrium nitrate using ammonium hydrogen carbonate as precipitant. Precipitation method (normal-strike or reverse-strike) and aging were found to have dramatic effects on cation homogeneity of the precursor, which in turn influenced the formation temperature of the YAG phase. Reactive YAG powders were produced from the reverse-strike-derived, as-synthesized precursors at temperatures ≤1200 °C. These powders densified to >98.0% of the theoretical density up to 1500 %C at a constant heating rate of 8 %C/min or to transparency by vacuum sintering at 1700 %C for 1 h without additives.

KxGaxSn8−xO16 (x ≤ 2) powders with hollandite structure were prepared by the sol-gel method using metal alkoxides. Dried gels, when being annealed at 973 K, changed to well-crystallized hollandite powders with about 22 m2/g in BET value which consisted of needle-like crystallites 25 nm wide and 65 nm long in average. The specific surface area was nearly 100 times larger than that of the hollandite produced at 1648 K by the conventional method, and the preparation temperature was lowered by 500 to 700 K. The powders obtained at 973 K were characterized as an attractive porous material showing a pore size distribution profile sharply monodispersed at 10.7 nm in the mesopore range.

Photoctalysis of a unique hollandite compound was investigated for the reductions of nitric oxide (NO) in gas phase and nitrate ion (NO3) in water with reducing agents under UV irradiation. Both NO and NO3 are hazardous chemicals to human. Recently, it was reported that titanium oxide (TiO2) photocatalyst perfomaed the oxidative decomposition of NO to NO3. However, an ideal photocatalytic removal of NO would be the reductive decomposition of NO to N2 and O2 without by-products. In this study, the surface activity of the unloaded hollandite, prepared by sol-gel method, was applied to the photocatalytic reaction. The present photocatalysis was quantitatively examined by using on-line mass spectrometry and ion chromatography, and the adsorption species on the hollandite surface was analyzed by in-situ IR spectroscopy. UV-ixradiated hollandite extu'bited high selectivity for the formation of N2 in the reductive decomposition of NO. Moreover, this catalyst also showed the reductive decomposition of NO3 to NO2 and N2 in water. In particular, the photocatalytic decomposition of NO3 would be a new pathway that has not been reported for popular photo-catalysts such as unloaded TiO2. Probably, this type compound is expected to have potentialities as a new type photocatalyst.