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Polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) may pose a worldwide pollution problem because of their persistence, long-range transport capability, and predisposition to bioaccumulate. The ubiquitous presence of PBBs and PBDEs has heightened interest in determination of their fate. We report results for a fugacity-based dynamic environmental and bioaccumulation model of the fate of hexabromobiphenyl (hexaBB) discharged into the Saginaw Bay region of Lake Huron, USA. We calculated transient fugacity profiles of hexaBB in Lake Huron and Lake Erie water and sediment during the 1970s, 1980s, and 1990s. The hexaBB concentrations in the environmental compartments were used as inputs for a dynamic bioaccumulation model of Lake Huron and Lake Erie aquatic biota. The model results indicate that the sediment compartments of Lakes Huron and Erie serve as reservoirs for the accumulation and slow transfer of hexaBB to the food web constituents of these lakes. We present bioaccumulation factors (BAFs) and compare the predicted hexaBB concentrations in lake trout from the bioaccumulation model with measurements during the period 1980 to 2000. An uncertainty analysis for this model suggests that errors associated with input parameter uncertainty can be reduced by refining estimates of the sediment degradation half-life of hexaBB. The corroborated PBB model has carryover application for modeling the fate of polybrominated diphenyl ether (PBDE) contaminants in the Great Lakes. By fitting model outputs to field measurement data using the transformed least square fit method, we report estimations of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) emission rates into the Lake Huron and Lake Erie watershed areas. Environ. Toxicol. Chem. 2011; 30:1018–1025. © 2011 SETAC

Stable alternative catalyst supports to replace conventional carbon-based materials in polymer electrolyte membrane fuel cells (PEMFCs) are being explored to achieve dramatic improvements in the performance and durability of fuel cells. Herein, conductive Ti3+ self-doped and carbon-coated TiO2-reduced graphene oxide (rGO) hollow nanosphere-supported Pt nanoparticles (Pt/rGO/TiO2) are investigated as cathode electrocatalysts for PEMFCs. Importantly, the rGO/TiO2 hollow nanospheres display excellent electrochemical stability under high potential cycling (1.2–1.7 V) compared with conventional carbon black (CB) support materials that normally induce electrochemical corrosion during fuel cell operation. The Pt/rGO/TiO2 is tested to establish its catalytic activity and stability using accelerated durability testing that mimics the conditions and degradation modes encountered during long-term fuel cell operation. The Pt/rGO/TiO2 cathode catalyst demonstrates comparable catalytic activity toward oxygen reduction and exhibits much higher stability than the Pt/CB one at high potentials in terms of minimal loss of the Pt electrochemical surface area. More importantly, Pt/rGO/TiO2 displays a negligible voltage drop over long-term cycling during practical fuel cell operation. The high stability of the Pt/rGO/TiO2 electrocatalyst synthesized in this investigation offers a new approach to improve the reliability and durability of PEMFC cathode catalysts.

Benzaldehyde (I) forms a Pt-bound pyrylium with PtCl2 that undergoes intermolecular [3 + 2] cycloaddition with alkenes to form oxygen-bridged intermediates with good stereoselectivity.