A series of GaN:Mg structures were grown in molecular beam epitaxy, using either one or two rf nitrogen sources, and in metalorganic chemical vapor deposition systems with varying Mg flux. Acceptor energies were measured using the Hall effect and admittance spectroscopy techniques. The acceptor energies were found to be different for the two methods, i.e., 135–155 meV for the Hall effect measurement and 80–115 meV for the admittance spectroscopy measurement. The apparently small acceptor energies from the admittance spectroscopy measurement were explained, through a simulation process, by the combined effects of (1) high Mg acceptor concentration with no other free carrier sources, and (2) the Mg emission kinetics assisted by the Frenkel–Poole field effect in the GaN:Mg structures.

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To improve the quality of boiled rice after storage in rice cookers, temperature was controlled at a lowered condition (45~65 o C repeated temperature cycling), compared to the present commercial rice cookers (75 o C). The effect of lowered temperature cycling on the microbial growth, color of rice, and reducing sugar production was measured. The bacteria Bacillus cereus and B. subtilis were killed at 75 o C and 45~65 o C cycling. The temperature cycling at 45~65 o C prevented an increase in colony forming unit of E. coli more than the steady temperature at 75 o C. Browning during storage was significantly decreased at 45~65 o C cycling, compared to 75 o C. The yellowness increase (Δb value of CIE parameters of the colorimeter) after the 3-day storage was 2.18 at 45~65 o C cycling whereas 9.12 at 75 o C. Reducing sugar was not produced at 75 o C and 45~65 o C cycling but produced at 30 o C because of the microbial growth. In conclusion, the temperature cycling at 45~65 o C can improve the quality of stored boiled rice by decreasing the browning and inhibiting the microbial growth.