Carbon-supported Fe–N x /C catalysts were synthesized at several pyrolysis temperatures such as 600, 700, 800, and 900 °C in the effort to investigate the temperature effect on the catalyst structures. The Fe contents in the synthesized catalysts were found to be about 1 wt % more than that in the Fe–TPPZ/C precursor complex (5 wt %), indicating that both the carbon support and complex ligand might be decomposed during the pyrolysis. X-ray diffraction (XRD) analysis revealed that the samples at 600–800 °C had no iron species segregation, while that formed at 900 °C showed the formation of Fe3C and Fe3O4, confirmed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and energy dispersive X-ray analysis (EDX) measurements. TEM images clearly showed that the large sizes of Fe3C and Fe3O4 species with a diameter of about 500 nm were wrapped up by a thin carbon layer. For Fe states, X-ray photoelectron spectroscopy (XPS) data revealed that Fe3+ was the dominant Fe species in the Fe–N x /C sample. Several nitrogen-containing species such as pyridinic N, the Fe–N(pyr) bond, quaternary N,N-oxides, as well as graphitic nitrogen were identified by XPS in the catalyst samples. Electrochemical characterization revealed a reversible Fe(III)–N x /Fe(II)–N x redox wave at 0.63 V vs RHE, which is believed to be the active sites for the oxygen reduction reaction (ORR). The density of this active site was found to be dependent on the pyrolysis temperature, and high densities were obtained in the temperature range of 700–800 °C. In addition, the morphology of the catalyst samples was also analyzed using the change of double-layer charge with the potential scan rate. Furthermore, the Fe–N x /C catalysts were found to have strong catalytic activity toward oxygen reduction reaction with an overall electron transfer number of 3.6.

Using the Glew-Hildebrand saturation technique, the solubilities of bis (2,2,6,6-tetramethyl-4-piperidinyl) maleate in hexane, heptane, octane, m-xylene, and tetrahydrofuran at temperatures from 253.15 K to 310.15 K were measured with the help of the classical equilibrium method. The experimental data were correlated with the modified Apelblat equation.

Using a laser monitoring observation technique, the solubilities of p-aminophenol in sulfuric acid + water have been determined experimentally from 286.15 K to 362.80 K. The experimental data were correlated with the modified Apelblat equation. The calculated results showed good agreement with the experimental data.

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This paper starts with a self-contained discussion of the so-called Akulov-Volkov action S AV , which is traditionally taken to be the leading-order action of Goldstino field. Explicit expressions for S AV and its chiral version S ch AV are presented. We then turn to the issue on how these actions are related to the leading-order action S NL proposed in the newly proposed constrained superfield formalism. We show that S NL may yield S AV /S ch AV or a totally different action S KS , depending on how the auxiliary field in the former is integrated out. However, S KS and S AV /S ch AV always yield the same S-matrix elements, as one would have expected from general considerations in quantum field theory.

Recently, the Fermi-LAT collaboration reported upper limits on the GeV gamma-ray flux from nearby clusters of galaxies. Motivated by these limits, we study corresponding constraints on gamma-ray emissions from two specific decaying dark matter models, one via grand unification scale suppressed operators and the other via R-parity violating operators. Both can account for the PAMELA and Fermi-LAT excesses of e ± . For GUT decaying dark matter, the gamma-rays from the M49 and Fornax clusters, with energy in the range of 1 to 10 GeV, lead to the most stringent constraints to date. As a result, this dark matter is disfavored with conventional model of e ± background. In addition, it is likely that some tension exists between the Fermi-LAT e ± excess and the gamma-ray constraints for any decaying dark matter model, provided conventional model of e ± background is adopted. Nevertheless, the GUT decaying dark matter can still solely account for the PAMELA positron fraction excess without violating the gamma-ray constraints.For the gravitino dark matter model with R-parity violation, cluster observations do not give tight constraints. This is because a different e ± background has been adopted which leads to relatively light dark matter mass around 200 GeV. *

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