Spinodal Decomposition in the Mg-Al-Fe-O System.

A supersaturated spinel solid solution having a nominal compositional ratio of Mg/Al/Fe = 0.5:1.0:1.5 was prepared using a conventional solid-state reaction at 1573 K in air followed by quenching in ice water. The formula of the resulting spinel structure compound (the spinel) was determined to be (Mg0.50AlFe0.262+Fe1.243+)0.97O4 based on a Rietveld refinement and thermogravimetry, indicating a cation-deficient spinel structure having mixed valences of Fe. This spinel was found to decompose to γ-Fe2O3 and a modified, Fe-poor spinel structure compound via a spinodal decomposition below 855 K. The spinodal temperature was estimated using the sidebands appearing in X-ray diffraction patterns in addition to the temperature dependence of magnetization values. This spinodal decomposition was accompanied by the oxidation of Fe2+ to Fe3+ and produced a unique grid-like microstructure (with a grid width of approximately 25 nm) along with enhancement of the saturated magnetization of the material. A sample cooled to room temperature in a furnace after heating at 1573 K in air had a lamella structure having a width of approximately 0.1 µm and comprised particles with a mixture of γ-Fe2O3 and the Fe-poor spinel compound on their surfaces. Subsequent heating of this same material to 1373 K in air formed ε-Fe2O3 in the particles. The crystallographic relationship between ε-Fe2O3 and the modified spinel structure compound was aε // [112̅]s, bε // [1̅10]s, and cε // [111]s (where ε and s indicate the ε-Fe2O3 and spinel, respectively).

[Intervention study using a fall prevention program to prevent functional decline of old-old elderly in a rural community].

The purpose of this study was to determine the effects of a fall prevention program for old-old elderly in a rural community in Japan. The subjects were 71 inhabitants aged 75 and over who used community health and welfare services such as day services and social activity classes. They were divided into two groups: 34 in the experimental group, and 37 controls. Physical therapists and care staff instructed the experimental group in fall prevention exercises once per two weeks from December 2000 to March 2001. The control group utilized the usual services without any special instructions. All subjects were evaluated by physical performance tests and a self-administered questionnaire before and after 4 months following the intervention. Collected data were analyzed by two-way ANOVA using intervention and time as independent variables, and physical performance tests as dependent variables. Twenty-three of the experimental group and 26 of the control group completed both baseline and follow-up surveys. There were no significant differences in physical ability between the two groups at the time of the baseline survey. The experimental group showed excellent compliance and participated in all sessions during the intervention period. Interaction effects on body mass index and Timed Up and Go Test were shown to be significant (F = 5.623, P < 0.01: F = 6.541, P < 0.05). There were no changes in terms of other physical and psychological factors. Our results showed specific exercises could improve some aspects of physical performance. Since the group exercise program can be effective for old-old elderly, it might contribute to decreasing falls and prolong independent living.