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The nitrogen doping effect on the Ge–Sb–Te recording layer was quantitatively examined. We succeeded in the quantitative analysis of the nitrogen concentration in the Ge–Sb–Te–(N) recording layer by secondary ion mass spectrometry (SIMS) observation. The nitrogen concentration could be finely controlled at a high deposition rate of 4.7 nm/s. The addition of a small amount of nitrogen remarkably improved the overwrite cycle numbers. We found that the most suitable nitrogen concentration was from 2 to 3 at%. We proposed a model to explain the nitrogen atom function in the recording layer. The nitrogen atoms produced nitrides, which are condensed near the grain boundaries of Ge–Sb–Te microcrystals. This resulted in the formation of very thin wrappings, which wrap the crystal grain in a manner similar to that of the peel of a peach and suppressed the micro-material flow. We achieved 8×105 overwrite cycles at λ=790 nm, N A=0.50 and using the pit position modulation (PPM) recording method where the minimum bit length is 0.87 µm.

The antioxidant activity of feruloyl arabinose, a model substance of cereal cell-wall fragments, in the LDL autoxidation system by CuSO 4 and its absorption were studied. Ferulic acid added as free acid showed little suppressive effect on LDL oxidation. However, ferulic acid sugar esters showed a positive effect. This fact indicated that affinity of LDL particle and free or bound ferulic acid is important for the suppressive effect. The HPLC analysis showed that in rats administered feruloyl arabinose, two peaks were detected with retention times lower than those of feruloyl arabinose and ferulic acid, which appeared upon β-glucuronidase/sulfatase treatment. The study showed that the absorbed form of FAA could be a more polar compound, possibly a conjugated form.

Phase-change random access memory (PRAM) technology is reviewed. PRAM uses the phase change between the amorphous state and the crystalline state caused by Joule heating as its memory mechanism. A change in electrical resistance owing to a phase change is detected by a small electric current. The merits of this approach are that the resistance change is more than one order of magnitude, and its simple structure decreases the number of steps in the manufacturing process. Suppression of reset current for the change from the lowresistance crystalline state to the amorphous state and an improvement in durability against set-reset cycles and high-temperature operation will ultimately be achieved.

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