Antioxidants mitigate radiation-induced lethality when started soon after radiation exposure, a delivery time that may not be practical due to difficulties in distribution and because the oral administration of such agents may require a delay beyond the prodromal stage of the radiation syndrome. We report the unexpected finding that antioxidant supplementation starting 24 h after total-body irradiation resulted in better survival than antioxidant supplementation started soon after the irradiation. The antioxidant dietary supplement was L-selenomethionine, sodium ascorbate, Nacetyl cysteine, α-lipoic acid, α-tocopherol succinate, and co-enzyme Q10. Total-body irradiation with 8 Gy in the absence of antioxidant supplementation was lethal by day 16. When antioxidant supplementation was started soon after irradiation, four of 14 mice survived. In contrast, 14 of 18 mice receiving antioxidant supplementation starting 24 h after irradiation were alive and well 30 days later. The numbers of spleen colonies and blood cells were higher in mice receiving antioxidant supplementation starting 24 h after irradiation than in mice receiving radiation alone. A diet supplemented with antioxidants administered starting 24 h after total-body irradiation improved bone marrow cell survival and mitigated lethality, with a radiation protection factor of approximately 1.18.
Pyrolyzed Fe/N/C,
a promising nonprecious-metal catalyst for oxygen reduction reaction
(ORR), usually relies on abundant micropores, which can host a large
amount of active sites. However, microporous structure suffers from
severe water flooding to break the triple-phase interface where ORR
occurs, especially in a direct methanol fuel cell (DMFC) fed with
liquid fuel. Current studies about the fabrication of a triple-phase
interface are mainly limited on a Pt/C catalyst layer, where mesopores
and macropores are concerned. Here, we successfully constructed a
triple-phase interface in micropores of Fe/N/C catalysts by controlling
the distribution of a hydrophobic additive, dimethyl silicon oil (DMS),
just partially penetrating into the micropores. The elaborately constructed
Fe/N/C-based DMFC can deliver high power density (102 and 130 mW cm–2 at 60 and 80 °C, respectively) and durability
comparable to that of Pt/C-based DMFC. This study presents a new avenue
to engineer catalyst microporous channels to boost the performance
of nonprecious-metal catalysts for fuel cells.
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