Exchange Process in the Dielectric Loss of Molecular and Macromolecular Ionic Conductors in the Interfacial Layers Formed by Electrode Polarization Effects.

Here we report a first analytical approach to determine the spectral dependence of the complex permittivity function of molecular and macromolecular ionic conductors in the interfacial layers formed by electrode polarization effects. We show that a previous model of electrode polarization effects that was successfully applied for describing the dielectric behavior of ionic liquids ( Serghei, A.; Tress, M.; Sangoro, J. R.; Kremer, F. Electrode polarization and charge transport at solid interfaces. Phys. Rev. B 2009 , 80 , 184301 ) can be now generalized and applied for polymer/ionic liquid blends as well as for poly(ionic liquid)s. The determined dielectric function of the interfacial layers reveals a dramatic change in the charge transport process manifested by a large decrease in conductivity. Our approach brings the first evidence for a relaxation peak detected in the dielectric loss of the interfaces, which is attributed to an exchange process between the interface and the bulk. This study gives new insights into the mechanism of charge transport at interfaces and could thus contribute to a better correlation between the dielectric properties of ion conducting materials and their electrochemical behavior at interfaces.

[Cancers arising from burn scars: 62 cases]. / Cancers sur cicatrice de brûlure: 62 cas.

INTRODUCTION: The development of cancer from burn scars is rare but not exceptional since 1 to 2 p. 100 of cutaneous cancers develop on burn scars. PATIENTS AND METHODS: We report a retrospective study of 62 cases arising from burn scars that account for 25 years at the Institute Salah Azaiez in Tunis. The epidemiological, clinic and prognosis characteristics of these cancers are discussed. RESULTS: Forty-five patients were male and seventeen were female. Their age varied from 22 to 83 years, with a mean age of 51.5 years. Limbs were affected in 85 p. 100 of the cases and the lower limbs in 58 p. 100. The mean size of the tumour was of 97 mm. Squamous cell carcinomas were the most frequent cancers arising from burn scar (95 p. 100). Basal cell carcinoma is arising only in two cases and malignant melanoma in one case. The treatment was curative for 49 patients: surgery and radiotherapy (31 cases), surgery only (14 cases) and radiotherapy (4 cases). The overall survival at 2 years, 3 years and 5 years was respectively 49.5 p. 100; 41.5 p. 100 and 37 p. 100. DISCUSSION: The improvement of prognosis depends not only on an earlier diagnosis and treatment, but also on the appropriate management of burns when they occurred.

[Skin aging]. / Le vieillissement cutané.

The skin aging is the result of the association of seven factors; chronological factor, genetic factors, exposure to ultraviolet rays (photodamage), behaviour factors, endocrinous, catabolics and mechanics factors. The treatment combine sun protection measures, topical treatment, dermatological and surgical techniques (peelings, resurfacing laser, injections of collagen, botulic toxin...). The authors intend to study clinical and anatomy-physiology aspect of skin aging, as well as different treatments.