Whenever water interacts with another dipolar entity, a broadening of its dielectric relaxation occurs. Often this broadening can be described by the Cole-Cole (CC) spectral function. A new phenomenological approach has been recently presented [A. Puzenko, P. Ben Ishai, and Y. Feldman, Phys. Rev. Lett. 105, 037601 (2010)] that illustrates a physical mechanism of the dipole-matrix interaction underlying the CC behavior in complex systems. By considering the relaxation amplitude Δε, the relaxation time τ, and the broadening parameter α, one can construct a set of 3D trajectories, representing the dynamic behavior of different systems under diverse conditions. Our hypothesis is that these trajectories will contribute to a deeper understanding of the dielectric properties of complex systems. The paper demonstrates how the model describes the state of water in aqueous solutions of non-ionic solutes. For this purpose complex dielectric spectra for aqueous solutions of D-glucose and D-fructose are analyzed.
Composite-solid electrolytes, in which ion-conducting polymers are combined with superionic ceramics, could revolutionize electrochemical-energy-storage devices enabling higher energy density, providing greater stability during operation and enhanced safety. However, the interfacial resistance between the ceramic and polymer phases strongly suppresses the ionic conductivity and presents the main obstacle to the use of these materials. Here, we emphasize the need for a distinct focus on reducing energy barriers to interfacial ion transport and improving the cation transference number. To achieve this goal, it is essential to develop a fundamental understanding of the parameters that influence the interfacial barriers to ion transport in composite electrolytes, and to understand the effect of the type of ceramic (“active” and “inert”) and its content on ion-transport phenomena. We suggest that adapting the polymer chemistry, mainly directed on polymerized ionic liquids, (PolyILs), and combined with functionalization of the surface of ceramic nanoparticles is a promising route for overcoming the high-energy-barrier challenge. Owing to high content of ion-conducting ceramics and high t+ of PolyILs, the fractional contribution of the migrating cationic species to the total ionic conductivity of polymer-in-ceramic electrolytes via an interfacial percolation path, will be close to unity, thus eliminating complications that might arise from emerging concentration gradients during the operation of solid-state batteries.
The application of dielectric spectroscopy (DS) to the study of bacteriorhodopsin (bR)-containing purple membrane films is presented in this paper. Two types of bR membrane films, oriented and nonoriented, were investigated in a wide frequency range (10 -2 -3 × 10 9 Hz) and temperature interval (5-70 °C). Four relaxation processes were observed in this frequency range and ascribed to different mechanisms, related to the structural units of the system. A large nonreversibility of the dielectric response as a result of heating and cooling has been observed in the slow processes implicating a change in the structure of the membrane stacking depending on the history of cooling and heating of the sample. Significant changes as large as 3 orders of magnitude in the mobility have been observed in this time scale. Comparison of the oriented and nonoriented bR membrane films was performed, and it was found that the oriented purple membrane has a unique liquid crystal-like ferroelectric behavior.
In this contribution, we report the application of time domain dielectric spectroscopy from 500 kHz to 1 GHz and differential scanning calorimetry to bacteriorhodopsin containing purple membrane films. The results of these measurements unexpectedly show that the oriented purple membrane has a unique liquid-crystal-like ferroelectric behavior. The dielectric behavior can be considered as soft mode relaxation processes in ferro-electric liquid crystals near smectic-C*−smectic-A phase transition. Such a phenomenon has not been previously observed in biological systems.
Cooperative dynamics of three-component water-oil-surfactant microemulsions based on sodium bis͑2-ethylhexyl͒ sulfosuccinate surfactant were investigated near the percolation threshold. The measurements were made by means of the time domain dielectric spectroscopy method in the temperature interval 12°C-40°C, including the percolation range. The data treatment was carried out in time domain in terms of the macroscopic dipole correlation functions ͑DCFs͒ related to the structural and kinetic properties of the system. It is shown that the DCF can be described by the Kohlrausch-Williams-Watts ͑KWW͒ expression exp͓Ϫ͑t/͒ ͔ ͑where is the relaxation time and is the stretched parameter͒, reflecting the peculiarities of the dipole interactions in a self-similar medium. For a physical interpretation of the phenomenological parameters and , a generalization of the known model of the cooperative relaxation was made. The model developed was adjusted for a description of the relaxation in microemulsions that have a fractal nature in the percolation region. The results obtained testify that parameters and in the KWW function are related to the structure of the system and reflect the cooperative behavior of microemulsion droplets near the percolation threshold. It was shown also that the macroscopic law of the relaxation of the KWW type is insensitive to the microscopic details of charge transport in the system and that there is a limited temporal range for the applicability of the stretched law of relaxation in time domain. In order to extend the initial temporal interval of the applicability of the relaxation function the correlation to the KWW term was found. ͓S1063-651X͑96͒09511-6͔
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