SUMMARY

Calcium ferrite oxides were prepared by calcining a mixture powder of iron-and calcium oxide. The 57 Fe-Mössbauer spectra of the calcium ferrites oxides were measured, revealing that the products should be Ca 2 Fe 2 O 5 and CaFe 2 O 4 , the ratio of which was dependent of the Fe/Ca atomic ratio of the mixture powder.

No abstract

Several types of calcium ferrite base catalysts (Ca/Fe = 0.33-3) for propylene (C 3 H 6 ) combustion were prepared. Calcium ferrite catalyst with brownmillerite crystal structure provided catalytic activity for C 3 H 6 combustion in the temperature range of 250-450°C. The brownmillerite phase (Ca 2 Fe 2 O 5 ) was responsible for the formation of oxygen adspecies (O 2 ) ) in the surface layer below 450°C.

While neurons in the lateral prefrontal cortex (PFC) encode spatial information during the performance of working memory tasks, they are also known to participate in subjective behavior such as spatial attention and action selection. In the present study, we analyzed the activity of primate PFC neurons during the performance of a free choice memory-guided saccade task in which the monkeys needed to choose a saccade direction by themselves. In trials when the receptive field location was subsequently chosen by the animal, PFC neurons with spatially selective visual response started to show greater activation before cue onset. This result suggests that the fluctuation of firing before cue presentation prematurely biased the representation of a certain spatial location and eventually encouraged the subsequent choice of that location. In addition, modulation of the activity by the animal's choice was observed only in neurons with high sustainability of activation and was also dependent on the spatial configuration of the visual cues. These findings were consistent with known characteristics of PFC neurons in information maintenance in spatial working memory function. These results suggest that precue fluctuation of spatial representation was shared and enhanced through the working memory network in the PFC and could finally influence the animal's free choice of saccade direction. The present study revealed that the PFC plays an important role in decision making in a free choice condition and that the dynamics of decision making are constrained by the network architecture embedded in this cortical area.