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© 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. ; [EN] Water and protein dynamics in two globular protein-water systems, water-lysozyme and water-BSA (bovine serum albumine), were studied by differential scanning calorimetry (DSC), dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarization currents (TSDC) techniques. Water equilibrium sorption isotherms (ESI) measurements were also recorded at room temperature. The samples covered a wide range of composition, from practically dry solid pellets (2wt% of water) to dilute solutions (82wt% of water). Crystallization and melting events of water were studied by DSC and the amount of uncrystallized water was calculated. The evolution of dynamics with hydration level was followed for various dielectric relaxation processes, the emphasis being given to relaxation processes of polar groups on the surface of the proteins and of uncrystallized water molecules. A relationship between the formation of a conductive percolating water cluster and the saturation of the water process was found. ; This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Heracleitus II. Investing in knowledge society through the European Social Fund. ; Kyritsis, A.; Panagopoulou, A.; Pissis, P.; Sabater I Serra, R.; Gómez Ribelles, JL.; Shinyashiki, N. (2012). Water and protein dynamics in protein-water mixtures over wide range of composition. IEEE Transactions on Dielectrics and Electrical Insulation. 19(4):1239-1246. ...

1239 1246 19 4 ; S ; © 2012 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. [EN] Water and protein dynamics in two globular protein-water systems, water-lysozyme and water-BSA (bovine serum albumine), were studied by differential scanning calorimetry (DSC), dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarization currents (TSDC) techniques. Water equilibrium sorption isotherms (ESI) measurements were also recorded at room temperature. The samples covered a wide range of composition, from practically dry solid pellets (2wt% of water) to dilute solutions (82wt% of water). Crystallization and melting events of water were studied by DSC and the amount of uncrystallized water was calculated. The evolution of dynamics with hydration level was followed for various dielectric relaxation processes, the emphasis being given to relaxation processes of polar groups on the surface of the proteins and of uncrystallized water molecules. A relationship between the formation of a conductive percolating water cluster and the saturation of the water process was found. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Heracleitus II. Investing in knowledge society through the European Social Fund. Kyritsis, A.; Panagopoulou, A.; Pissis, P.; Sabater I Serra, R.; Gómez Ribelles, JL.; Shinyashiki, N. (2012). Water and protein dynamics in protein-water mixtures over wide range of composition. IEEE Transactions on Dielectrics and Electrical Insulation. 19(4):1239-1246. ...

[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 paper ; Gómez-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. ...