Nanocomposite Polymer Electrolyte Membranes: Methanol Crossover and Conductivity

Commercial Nafion® 117 membranes were successfully modified by in-situ reactions (sol-gel of TEOS and/or polymerization of aniline) within Nafion structures. Water-methanol permeability and proton conductivity were investigated in order to determine the potential performance of these membranes for DMFC systems. Silica-polyaniline modification resulted in 84% methanol crossover reduction, from 2.45x10^-5 cm2.s^-1 for conventional Nafion membranes to 3.71x10^-6 cm2.s^-1 for the modified silica-polyaniline composite membrane at 75 degrees C. In addition, conductivity was not hindered, as the polyaniline-Nafion membrane increased from 12.2 to 15 mS.cm^-1 as compared to Nafion, while a reduction of 11% was observed for silica-polyaniline-Nafion composite membrane. The results in this work strongly suggest the potential of polyaniline nanocomposites to enhance the performance of DMFCs.

Examining the influence of biological and psychological factors on cognitive performance in chronic fatigue syndrome: A randomized, double-blind, placebo-controlled, crossover study

The pathophysiology of chronic fatigue syndrome (CFS) remains unclear; however, both biological and psychological factors have been implicated in establishing or maintaining this condition. People with CFS report significant and disabling cognitive difficulties such as impaired concentration that in some cases are exacerbated by exposure to chemical triggers. The aim of this study was to determine if neuropsychological deficits in CFS are triggered by exposure to chemicals, or perceptions about the properties of these substances. Participants were 36 people with a primary diagnosis of CFS, defined according to Centers for Disease Control (CDC) criteria. A randomized, double-blind, placebo-controlled, crossover design was used, with objective assessment of neuropsychological function and participant rating of substance type, before and after exposure to placebo or chemical trigger. Results showed decrements in neuropsychological tests scores on three out of four outcome measures when participants rated the substance they had been exposed to as chemical. No change in performance was found based on actual substance type. These results suggest that cognitive attributions about exposure substances in people with CFS may be associated with worse performance on neuropsychological tasks. In addition, these findings suggest that psychological interventions aimed at modifying substance-related cognitions may reduce some symptoms of CFS.