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Showing 1 to 20 of 21 for “"dielectric relaxation"”.
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Dielectric relaxation time spectroscopy for tissue characterisation
… Experimental observations of the existence of dielectric dispersions caused by distributions of dielectric relaxation time (DRT) constants were made on different types of biological material. It is postulated that widely used approaches for modelling these electrical properties are …
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Dielectric relaxation behavior of poly(3-hydroxybutyrate)
… blending with other polymers which possess high relaxation behavior at room temperature seems attractive. Prior to such development, the fundamental characterization of the relaxation behavior of PHB itself is extremely important in order to assess the effect of any attempt to improve the …
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The dielectric relaxation of chlorostyrene polymers in solution
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1960.
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Conformational analysis and dielectric relaxation of polycarbosilanes and related materials
… mean-square radius of gyration. In addition, the dielectric relaxation behaviour of two samples of poly(2,2,5,5-tetramethyl-1-oxa-2,5-disilapentane) with molar masses Mw = 28000 and Mw = 46000 respectively, have been studied as a function of temperature (179K-205K) and frequency (100-105Hz). …
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Dielectric Relaxation Processes at Apical Membranes of Frog Skin: Changes of Capacitance and Sodium Ion Channel Density
… spectrum of apical membranes exhibited multiple relaxation processes, where some membranes exhibited two relaxation processes while others exhibited three relaxation processes. Each relaxation process could be described by the Cole-Cole equation (1941), consisting of a static capacitance …
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Part One: Extensions of the E and C Equation. Part Two: Measurements of Dielectric Relaxation in Strontium Doped Lanthanum Orthoferrites Using Dielectric Time Domain Spectroscopy
Part One. The relationships between the Kamlet-Taft $\beta$-$\pi\sp\*$ solvation approach and the E and C equation are investigated. The breakup of solvation effects into nonspecific ($\pi\sp\*$) and specific Lewis base interactions ($\beta$) is found to be consistent with the E and C approach. The …
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Cluster kinetics modeling of glassforming materials
… a new model relating temperature and pressure to dielectric relaxation or viscosity of a glassformer is developed. The model is based upon cluster kinetics, reaction-like mechanisms describing interactions between glassformer monomers and their clusters. Mathematical solutions of population …
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Conduction noise in sliding charge-density waves
… saturation occurs when fo exceeds the material's dielectric relaxation frequency; and the size of the noise in blue bronze increases linearly with specimen length. The principal conclusions of this work are: randomness is central to CDW dynamics; the rms voltage is a reliable and precise …
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Electromagnetic radiation calorimetry of thermoplastics, elastomers and composites systems
… Low frequency dynamic mechanical and dielectric frequency-temperature spectra were obtained on the materials and combined to conveniently extrapolate structure-property relationships into the GHz region. A correlation was found between the dielectric properties of various polymers and …
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Microstructure and Electrical Properties of Mocvd-Derived Perovskite Lead Zirconium(x) Titanium(1-X) Oxygen(3) and Lead (Scandium Tantalum)(1-X) Titanium(x) Oxygen(3) Thin Films on Lanthanum Nickel Oxide Electrode-Buffered Silicon
… ferroelectric thin film was characterized by its dielectric dispersion. Moreover, effect of an AC field on the dielectric relaxation behavior of the relaxor PSTT thin films was studied. The results were qualitatively explained by the current theories of relaxor ferroelectrics. Pyroelectric …
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The development of micro-sample electrical impedance analysis for freeze-drying process development
… prediction of freezing/drying rate, (3) study dielectric relaxation of ice and sugar solutions using interdigitate electrode and evaluate using electrical circuit elements. Method: The initial stage of the project involved a comprehensive study of water/ice using the broadband frequency range …
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Through Vial Impedance Spectroscopy (TVIS): A novel process analytical technology for investigating the thawing of frozen cell suspensions.
… that has attempted to explore the application of dielectric spectroscopy to an understanding of cryopreservation mechanisms; which is surprising given that the dielectric relaxation of ice may be measured in relatively simply experimental studies of bulk suspensions of cells. Such studies have …
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Low Frequency Dielectric Investigations on Hydrated Pharmaceutical Powders
Measurements of dielectric properties on hydrated systems at low frequencies, present particular difficulties with regard to the phenomenon of electrode polarisation, which can mask the dielectric properties of the sample. The reproducibility of DRS measurements on powdered systems has also been …
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Interaction of Metal Salts with Polyethers
The dielectric properties of pure low to medium molecular weight poly(ethylene glycol) and poly(propylene glycol) and a variety of their salt complexes have been studied through the measurement of the dielectric permittivity and dielectric loss over a range of frequency and temperature. The major …
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A dielectric study of systems exhibiting molecular association.
… and micellar solutions of nonionic surfactants. Dielectric relaxation studies have shown that addition of water to an alcohol causes a reduction in the relaxation time of the principal dispersion which for all compositions is Debye-type. The relaxation behaviour has been interpreted using a model …
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Asymptotic and numerical analysis of time-dependent wave propagation in dispersive dielectric media that exhibit fractional relaxation
… pulse propagation through anomalously dispersive dielectric media. The Havriliak-Negami (H-N) and Cole-Cole (C-C) models capture the non-exponential nature of such dielectric relaxation phenomena, which is manifest in a variety of dispersive dielectric media. In the C-C model, the dielectric …
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Coupling of the electrical, mechanical and optical response in polymer/liquid-crystal composites
… The anchoring effect is studied by means of dielectric relaxation spectroscopy. Two dispersion regions are observed in the dielectric spectra of the pure P(VDF-TrFE) film. They are related to the glass transition and to a charge-carrier relaxation, respectively. In PDLC films containing 10 …
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A study of the mechanisms of milling-induced enhancement of solubility and dissolution rate of poorly soluble drugs
… techniques, specifically, SEM, DSC, TGA, THz and dielectric spectroscopy. The second aim of the project was to investigate the impact of milling and co-milling on the solubility and dissolution rate of ibuprofen after co-milling with a variety of excipients (polymer and surfactants). The principle …
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Transistor-based biosensing: expanding the functionality of field effect transistors
… These fringing electric fields can be used for dielectric relaxation of water molecules to generate heat for DNA denaturation as discussed in chapter 3, or to generate a transmembrane potential across a cellular membrane for ultra-localized cell lysis as discussed in chapter 4. These methods …
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Synthesis and Properties of Ion-Containing Block and Segmented Copolymers and Their Composites
… reduced imidazolium hard segment Tg. Dielectric relaxation spectroscopy demonstrated that ionic conductivity of imidazolium-containing segmented polyurethanes increased by five orders of magnitude upon incorporation of 30 wt% EMIm ES. Imidazolium-containing sulfonated pentablock …
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