1,829 research outputs found
Entropy of Pairs of Dual Attractors in 6D/7D
We study the attractor mechanism of dual pairs of black brane bounds in N=2
supergravity in six and seven dimensions. First, we consider the effective
potentials of the 6D and 7D black branes as well as their entropies. The
contribution coming from the SO(1,1) factor of the moduli spaces M_{6D} and
M_{7D} of these theories is carefully analyzed and it is used to motivate the
study of the dual black branes bounds; which in turn allow to fix the critical
value of the dilaton at horizon. The attractor eqs of the black branes and the
bound pairs are derived by combining the criticality conditions of the
corresponding effective potentials and the Lagrange multiplier method capturing
constraints eqs on the fields moduli.Comment: 55 pages, 2 figures, To appear in JHE
HyperKhaler Metrics Building and Integrable Models
Methods developed for the analysis of integrable systems are used to study
the problem of hyperK\"ahler metrics building as formulated in D=2 N=4
supersymmetric harmonic superspace. We show, in particular, that the constraint
equation and its
Toda like generalizations are integrable. Explicit solutions together with the
conserved currents generating the symmetry responsible of the integrability of
these equations are given. Other features are also discussedComment: Latex file, 12 page
Effects of sulfonation process on thermal behavior and microstructure of sulfonated polysulfone membranes as a material for Proton Exchange Membrane (PEM)
This paper reports the effect of sulfonation processon thermal behavior and microstrucutre of sulfonated polysulfone membrane. Various degree of sulfonation reactin has been conducted and the sulfonated membranes were characterized by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), x-ray diffraction (XRD) and scanning electron microscopy (SEM). Modifications of the origin polysulfone polymer resulted in an increment value of glass transition temperature (Tg) due to the introduction of sulfonic acid group to the polymer backbone. However, due to some hindrance such as trace amount of organic solvent left during solvent evaporation and high hydrophilicity of the produced sulfonated membranes resulted in decreasing values of Tg. The polymer membrane showed lower degradation temperature as a function of degree of sulfonation. From XRD analysis, it was found that the membrane shows slight crystalline behavior after the sulfonation reaction. Detail discussions and observation of the alteration in microstructure of the sulfonated membrane were supported by SEM micrograph
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