Studien Über die Saponine aus der Arznei-Ginseng-Wurzel: Massenspektren von Ginsenoside-Rg1-Decaacetat und Verwandten Verbindungen

Mass spectra of ginsenoside-Rg1 deca-acetate

1 Siehe Lit.2.

and the related dammaran-type triterpene saponin acetates have been studied and a comment is given on the structure of panaxoside A (=ginsenoside-Rg1) proposed by Elyakov, et al .     

Dielectric relaxation in the paracrystalline phase in polyacrylonitrile

Thermal expansion and dielectric relaxation of polyacrylonitrile were measured in the temperature range from ?75 to 152°C. at frequencies from 30 cps to 3 Mc./sec. The thermal expansion curve and the temperature dependence of logarithmic relaxation time both show an inflection at 85°C. An x-ray study by Bohn reveals that this inflection comes from the thermal expansion of the paracrystalline phase of this polymer, and consequently the transition at 85°C. and the associated relaxation are ascribed to molecular motion in the paracrystalline phase. The relaxation strength increases with increasing temperature above this point. The transition is caused by freezing of the bending vibration of chains whereas the relaxation results from rotational vibration. The length of segments in this phase is roughly estimated to be ca. 100 A. by comparing the observed relaxation strength with the theory developed on the basis of the above considerations.