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Holly L. S. Salerno Frederick L. Beyer Yossef A. Elabd 《Journal of Polymer Science.Polymer Physics》2012,50(8):552-562
Robust hydroxide conducting membranes are required for long‐lasting, low‐cost solid alkaline fuel cells (AFCs). In this study, we synthesize Nafion‐based anion exchange membranes (AEMs) via amination of the Nafion precursor membrane with 1,4‐dimethylpiperazine. This initial reaction produces an AEM with covalently attached dimethylpiperazinium cations neutralized with fluoride anions, while a subsequent ion exchange reaction produces a hydroxide ion conducting membrane. These AEMs possess high thermal stability and different thermal transition temperatures compared to Nafion, while small‐angle X‐ray scattering reveals a similar ionic morphology. The hydroxide ion conductivity of the Nafion‐based AEM is fivefold lower than the proton conductivity of Nafion at 80 °C and 90% relative humidity. More importantly, the hydroxide conductivity is insensitive to drying and rehydrating the membrane, which is atypical of other AEMs with quaternary ammonium cations. The high chemical and thermal stability of this hydroxide conducting Nafion‐based AEM provides a promising alternative for AFCs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
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Mean field calculations of the Peierls instability have been carried out for arbitrary bandfilling both in the case of free electrons as well as for the tightbinding approximation. New expressions for Δ(0) and Tp are derived which change the experimentally derived λ to a more reasonable value. Δ(0)/kBTp may differ significantly from the BCS value 1.76 in the tightbinding approximation. 相似文献
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G. Beyer A. Jasiński O. Knotek H.-G. Ortlepp H.-U. Siebert R. Arlt E. Herrmann G. Musiol H. Tyrroff 《Nuclear Physics A》1976,260(2):269-286
Radioactive sources of 123, 125, 127, 129Ba obtained in the spallation reaction have been studied with Ge(Li), Si(Li), NaI(Tl) and plastic detectors. On the basis of γ-ray energies, intensities, energy sums and coincidence information, the decay scheme has been proposed for 127Ba. No high-spin isomer of 127Ba has been observed. The lifetimes of + → + transitions in 123, 125, 127, 129Cs have been measured. No evidence for the shape isomerism in 127Cs has been found. 相似文献
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J. Herion M. Tapiero J. P. Zielinger N. Benjelloun-Saki W. Beyer 《Fresenius' Journal of Analytical Chemistry》1989,333(4-5):531-534
Summary Photo-induced current transient spectroscopy (PICTS) was performed for thin films of undoped hydrogenated amorphous silicon (a-SiH). Existing theoretical models i.e. the standard model of PICTS (the transient currents are limited by thermal emission of carriers from localized to mobile states) and the recombination model due to Rose (the transient currents are limited by recombination) fail to describe the experimental data. It is concluded that the recombination model has to be extended to arbitrary distributions of the density of states in order to be applicable to the present case.
Untersuchung tiefer Zustände in dünnen Schichten von wasserstoffhaltigem amorphem Silicium mit Hilfe der Photostrom-Transienten-Spektroskopie相似文献