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Abstract. The electrical conductivity in the ZrO2-Ln203 and ZrO2-MO2-Ln203(M = Hf, Ce, Ln = lanthanides) systems has been examined.The highest conductivity of 0.3 S/cm at 1000 ~ was found in the ZrO2-Sc203 system. The addition of MO2 into the ZrO2-Ln203(Ln = Sc, Y, Yb) systems showed the conductivity decreasing. The conduction mechanism in the zirconia based oxide ion conductors was discussed in view of the dopant ionic radius. The aging effect of the conductivity in the ZrO2-Ln203 systems has been measured in a temperature rang 800-1000 ~ ZrO2 with a high content of Ln203 showed no significant conductivity degradation.

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A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, . The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection.