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Some dietary fibers originated from insects such as silkworm (Sericin) and others along with constituents of several representative seaweeds such as wakame Undaria pinnatifida; hijiki Hizikia fusifome; and kombu Laminaria japonica, were found to have fairly large reaction rates determined by quenching experiments of emission spectra in the near-infrared region lambdamax 1270 nm for singlet oxygen 1O2, Cypridina luminescence method for superoxide, and peroxide value (POV) for autoxidation. The determined reaction rates are between 10(3)-10(5) (g/L)(-1) s(-1) for the insect and the plant dietary fibers; the larger ones are as large as that of ascorbic acid, 1.93 x 10(4) (g/L)(-1) s(-1) for singlet oxygen. Most of these seaweed constituents also showed antioxidative activity against autoxidation and superoxide as well as their immunological enhancing activity. These results suggest a possibility that dietary fibers that are supposed to prevent the large-intestine cancer by their physical properties may prevent the cancer, at least in parts, by their chemical, antioxidative activity.

The dehydration of 1,3-butanediol was investigated over CeO 2 -ZrO 2 catalysts prepared by impregnation at temperatures of 325-375°C. Pure CeO 2 selectively catalyzed the dehydration of 1,3-butanediol to form 3-buten-2-ol and 2-buten-1-ol, while pure ZrO 2 , which was less active than pure CeO 2 , catalyzed the dehydration to 3-buten-1-ol. In the CeO 2 /ZrO 2 catalyst in which CeO 2 was supported on zirconia, the presence of a small amount of CeO 2 suppressed the formation of 3-buten-1-ol and induced the dehydration of 1,3-butanediol to form 3-buten-2-ol and 2-buten-1-ol and the subsequent dehydrogenation of 3-buten-2-ol to form 3-buten-2-one and butanone. The activity would be related to the redox features of CeO 2 . The monoclinic phase of zirconia support decreased while the cubic CeO 2 phase increased as CeO 2 content was increased. In contrast, in the ZrO 2 /CeO 2 catalyst in which ZrO 2 was supported on cubic CeO 2 , only the cubic CeO 2 phase was observed and ZrO 2 species appeared in the form of a solid solution of CeO 2 -ZrO 2 with fluorite structure. Regardless of zirconia loading, ZrO 2 species did not affect the catalytic activity of ZrO 2 /CeO 2 , which was controlled by CeO 2 species.

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