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The industrial chemical 1,3-butadiene (BD) is a potent carcinogen in mice and a weak one in rats. This difference is generally related to species-specific burdens by the metabolites 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 3,4-epoxy-1,2-butanediol (EBD), which are all formed in the liver. Only limited data exist on BD metabolism in the rodent liver. Therefore, metabolism of BD, its epoxides, and the intermediate 3-butene-1,2-diol (B-diol) was studied in once-through perfused livers of male B6C3F1 mice and Sprague-Dawley rats. In BD perfusions, predominantly EB and B-diol were found (both species). DEB and EBD were additionally detected in mouse livers. Metabolism of BD showed saturation kinetics (both species). In EB perfusions, B-diol, EBD, and DEB were formed with B-diol being the major metabolite. Net formation of DEB was larger in mouse than in rat livers. In both species, hepatic clearance (Cl(H)) of EB was slightly smaller than the perfusion flow. In DEB perfusions, EBD was formed as a major metabolite. Cl(H) of DEB was 61% (mouse) and 73% (rat) of the perfusion flow. In the B-diol-perfused rat liver, EBD was formed as a minor metabolite. Cl(H) of B-diol was 53% (mouse) and 34% (rat) of the perfusion flow. In EBD-perfused rat livers, Cl(H) of EBD represented only 22% of the perfusion flow. There is evidence for qualitative species differences with regard to the enzymes involved in BD metabolism. The first quantitative findings in whole livers showing intrahepatic first-pass metabolism of BD and EB metabolites will improve the risk estimation of BD.

Improving manganese oxides as cathodic catalysts in direct methanol/hydrogen peroxide fuel cells by incorporation of Cu and Fe to promote oxygen reduction (OR) and hydrogen peroxide reduction (HPR) is reported. The Cu‐incorporated and Fe‐incorporated MnxOy were prepared by impregnation and solvothermal processes. From XRD, XPS, and XAS analyses, the obtained MnxOy consisted of MnO2 and mixed phases of Mn3O4 and Mn2O3 from impregnation and solvothermal methods, respectively. The Cu‐incorporated and Fe‐incorporated MnxOy included CuO and Fe2O3, respectively, through both methods. Addition of Cu and Fe decreased the BET surface area and increased the pore sizes as compared to the pristine MnO2. With the Fe : Mn molar ratio of 0.20 : 1, the Fe‐incorporated MnxOy from the solvothermal method presented the highest cathodic peaks under the cyclic voltammogram of HPR and OR at around 0.59 V of 11.59 mA cm−2 and −0.59 V of −12.33 mA cm−2, respectively. Compared to the Cu‐incorporated ones, the highest HPR peak at 0.68 V of 9.20 mA cm−2 and the highest OR peak at −0.59 V of −6.99 mA cm−2 were obtained from the Cu‐incorporated MnxOy prepared through the solvothermal method at the Cu : Mn molar ratio of 0.15 : 1. Incorporating Cu or Fe into MnO2 brought the improvement of electrocatalytic activity for HPR and OR. The Cu‐incorporated and Fe‐incorporated MnxOy from both methods showed a higher power density of μ‐DMFC than the pristine MnO2.