Poly(ethyl methacrylate-co-hydroxyethyl acrylate) random co-polymers: Dielectric and dynamic-mechanical characterization

[EN] The conformational mobility in poly(ethyl methacrylate-co-hydrxyethyl acrylate) co-polymers was studied by dielectric relaxation spectroscopy, thermally stimulated depolarization currents and dynamic-mechanical experiments. The relaxation strength and the shape of the dielectric relaxation spectra of the homopolymer and co-polymer networks were analyzed using the Havriliak-Negami equation. The dependence of the relaxation strength on co-polymer composition and temperature was analyzed taking into account the merging of the main and the secondary relaxation processes. The shape of the epsilon" versus frequency plots led to the conclusion that the distribution of relaxation times was broader in the co-polymers with intermediate composition than in the homopolymers, a feature that can be explained by the inhomogeneity produced at molecular scale by the sequence distribution of the monomeric units along the chain. Master curves were built both for the elastic modulus and the mechanical loss tangent, and the temperature dependence of the relaxation times was deduced from the shift factors. The fit to the Vogel equation permitted the calculation of the strength parameter, which is higher in the co-polymers that the simple average of the values of the homopolymers, a feature that can be related to the broadness of the distribution of relaxation times.The authors are grateful for the support given by the Spanish Science and Technology Ministry through the MAT2003-05391-C03-01 project and by the Valencian Regional Government (Generalitat Valenciana) through the GRUPOS03/018 project. We would like to thank the R + D + i Linguistic Assistance Office at the Universidad Polite´cnica de Valencia for their help in revising this paperGómez-Tejedor, JA.; Rodríguez Acosta, T.; Gómez Ribelles, JL.; Polizos, G.; Pissis, P. (2007). Poly(ethyl methacrylate-co-hydroxyethyl acrylate) random co-polymers: Dielectric and dynamic-mechanical characterization. Journal of Non-Crystalline Solids. 353(3):276-285. https://doi.org/10.1016/j.jnoncrysol.2006.11.003S276285353

Advanced intrahepatic cholangiocarcinoma in hepatitis C virus-related decompensated cirrhosis: case report and review of the literature

A 75-year-old man with no known previous liver disease was admitted to our institution because of right pleural effusion, backache, and pain in the upper right quadrant. Physical and laboratory work-up revealed decompensated liver cirrhosis. Spiral computed tomography (CT) showed a 6-cm tumour in the right liver lobe. Serum levels of aminotransferases, prothrombin time, total bilirubin, alphafetoprotein and carcinoembryonic antigen were within normal limits. However, the patient had elevated cholestatic enzymes, diffuse hypergammaglobulinaemia, a six-fold increase in carbohydrate antigen 19-9 (CA 19-9), cryoglobulinaemia, and reactivity against hepatitis C virus (anti-HCV). Although hepatocellular carcinoma is the most common cancer in a cirrhotic patient with chronic viral hepatitis, the investigation revealed the presence of intrahepatic cholangiocarcinoma (ICC). This is a less frequently occurring primary liver tumour, the aetiology and pathogenesis of which remain unclear in the majority of cases. The coexistence of HCV liver disease and ICC might be an incidental finding, but recently some reports have shown a relatively high incidence of this tumour in patients with HCV-related cirrhosis. The current aspects regarding ICC prevalence in HCV patients, the possible aetiopathogenetic links between this tumour and HCV, and the importance for ICC detection and characterization using the enhancement patterns with quadruple-phase spiral CT scan are also discussed