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The polystyrene sulfonic acid resin catalysts were fabricated, containing elements of Cl and Mg through oxidization and impregnation, and they were characterized by EDS, FT-IR spectra, Py-IR spectra, UV spectra, XPS and TGA to investigate their physiochemical properties. The catalytic performances of these catalysts were examined in the esterification reaction of succinic acid with n-butanol, and the catalytic results showed that modified resins exhibited the highest catalytic activity and achieved a high yield of dibutyl succinate (91.6%) in addition, the modified resin generated new Lewis acid sites and showed significantly higher thermal stability. The experimental results demonstrated that the Mg2+ coordinated with a sulfonic acid group to form stable active sites, which effectively decreased the deactivation caused by the thermal degradation of sulfonic acid. Moreover, the monomer structures of polystyrene sulfonic acid resin and modified polystyrene sulfonic acid resin have been modelled using B3LYP/6-311G(d,p) approximation.

Tapu, una novela corta, dio comienzo a la fama de Liu Zhenyun y, en buena parte, mostró su sello personal. Tapu es un pueblo cuyo nombre deriva de una pagoda chueca, sin techo, en cuya cercanía está la escuela donde el personaje central y narrador de esta historia presenta el examen para entrar a la universidad. Tapu puede ser cualquier aldea china donde jóvenes campesinos en los finales de la década de los setenta depositaban todas sus esperanzas de un mejor futuro.