The preparation and oxygen permeability of composites of Ce0.8Gd0.2O2-ö (GDC) and spinel-type ferrites, MFe2O4 (M = Co and Mn) have been investigated. The composites of GDC -x vol% MFe2O4, where x ranged from 5 to 65, were prepared by a citrate-based liquid-mix technique. The composites were found to be almost fully densified by sintering at 1300 °C for 2 h. From TEM observations, the grain size of GDC and spinel-type phases was found to be less than 0.5 μm. In the case of M = Co, GDC - 25 vol% CoFe2O4 with a membrane thickness of 1.0 mm exhibited an oxygen flux density of 0.21 μmol·cm-2·s-1 under the P(O2) difference between He (20 sccm) and air at 1000 °C. Under reducing atmosphere of Ar-5%H2, the oxygen flux density of this composite increased up to 1.3 μmol·cm-2·s-1. Moreover, under Ar-10%CH4 gas flow, GDC - 15 vol% MnFe2O4 with a membrane thickness of 0.24 mm exhibited the oxygen flux density of 2 and 7 μmol·cm- · s- at 800 and 1000 °C, respectively.

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Effects of Light and gibberellic acid (GA3) application on the germination of Dioscorea tokoro Makino and Dioscorea tenuipes Franch. et Savat. were observed. For complete germination, seeds of both species required prechilling in moist condition before incubation at a higher temperture. Red Ught irradiation during the incubation after the prechilling promoted germination; blue, green, or far red light markedly inhibited the germination of both species.Application of GA3 induced complicated changes in the germination of both species in relation to light quality. In the germination of D. tokoro, GA3 inhibited in the dark and red; however, i promoted germination in blue and far red light. GA3 promoted germination of D. tenuipes in the dark and in blue, green, or far red lght. These phenomena are explainable by assuming two counteractive reactions (germination-promoting and germination-inhibiting) which are both activated by applied GA3.Gibberellin is well known to break dormancy of seeds and buds in many plants (3,11). However, in bulbils of Begonia evansiana (2,(4)(5)(6)(7)9) and also bulbils and subterranean dormant organs of some species in the genus Dioscorea (8, 10), dormancy is induced by endogenous and exogenous gibberellin. Sprouting in winter buds of some woody plants is also retarded by applied gibberellin (1, 12). In seeds, however, no information about the germination-inhibiting effect of gibberellin seems to have been published.We have studied comparative physiology in dormancy of seeds and buds of many species of the genus Dioscorea, perennial monocotyledonous herbaceous plants, which range from the tropics to the cold temperate zones. In the present paper, we tested light and temperature effect on germination and GA3-induced germination inhibition in seeds of Dioscorea tokoro and Prefecture) of Japan, dried at room temperature, and then stored in a desiccator containing silica gel until used. In germination experiments, 40 to 70 seeds were placed in a 9-cm Petri dish on a thin layer of absorbent cotton moistened with distilled H20 or aqueous solutions of GA3 (gift from Kyowa Fermentation Industries, Tokyo) and allowed to stand under various light conditions at 25 or 26 C in D. tokoro and 20 C in D. tenuipes. In some experiments, prior to incubation at the above conditions, the seeds were placed under 5 C in the dark in a Petri dish on a thin layer of absorbent cotton moistened with distilled H20 (prechilling).White light of 1,500 lux was obtained from real daylight (40-D-SDL, Toshiba, Tokyo) fluorescent lamps. Blue, green, and red light were obtained by filtering the radiations from colored fluorescent lamps (FL-20BF, FL-20GF, and FL-20RF, respectively, Mitsubishi, Tokyo) through a 1-mm thickness of blue, green, and red vinyl resin plates, respectively. For far red irradiation, light from medical IR incandescent lamps (Toshiba) was filtered through 10-cm of distilled H20 and a 1-mm thickness of red and blue vinyl resin plates. Approximate wavelength of peak and half-bandwidth of colored light...

Undoped and Tb3+ -doped HfO2 spherical particles were prepared by a sol-gel method, by using hafnium tetra-t-butoxide (Hf(O-t-C4H9)4) as a precursor of hafnium dioxide, SPAN85 ® as a surfactant, mixed solvent of C2H5OH and n-C4H9OH, and H2O, followed by investigation of their structural and optical properties. Spherical particles with good morphology and comparatively high dispersibility were obtained from solutions with the molar ratio SPAN85 ® :H2O = 1:8-17.5, their sizes being 0.2-5 μm in diameter. Particles became small and aggregated when the molar ratio of H2O was more than 17.5, but became large when it was less than 8. Spherical particles heat treated at 400°C or below were amorphous, and those heat treated at 600°C or above were crystallized. Tb 3+ -doped HfO2 spherical particles showed green luminescence due to the 5 D4→ 7 FJ (J = 6, 5, 4, 3) transitions of the Tb 3+ ion, and relatively strong luminescence was observed both in dried gel particles and particles heat treated at 1000°C. These Tb 3+ -doped HfO2 spherical particles can be expected for new optical materials.