Cole Plots Research Articles

AC Impedance Analysis of Blend Polymer Electrolyte of PVP – PPA with Magnesium Salts as an Ionic Dopant for Potential Battery Applications

Abstract Solid polymer electrolyte films containing blend polymer electrolyte of Polyvinylpyrrolidone (PVP) and Poly p - amino benzoic acid (PPA) with varying ratios of magnesium salts were synthesized by solution casting method. Their conduction and relaxation mechanisms were studied by impedance spectroscopy (AC) at room temperature. The dependence of electrical data on frequency was analyzed by Cole – Cole plot and Jonscher’s power law. The semicircle seen in the plot represents the double relaxation process and shows how bulk electrolyte and the interfacial effect contribute to non-Debye and electrical conduction. The ac and dc conductivity values were calculated and the conductivity variation for the blend polymer PVP – PPA doped with different concentrations of magnesium salts was explained by the ionic contribution of the electrolytes. The dielectric constant and dielectric loss were measured by the dielectric investigations. The relaxation phenomenon of these electrolytes is provided by the dissipation factor analysis and electric modulus value. The conductivity of the system determines the suitability of the thin film concentration for potential battery applications as a polymer electrolyte.

Impedance Spectroscopy and Study of Electrical Properties of Pb(Zr<sub>0.52</sub>Ti<sub>0.48</sub>)<sub>1-x</sub>Fe<sub>x</sub>O<sub>3-x</sub> (0≤x≤0.20) Ceramics

Iron substituted Lead zirconate titanate nanoparticles Pb (Zr0.52Ti0.48) 1-x FexO3-x (PZTFx) (for (x=0.00, 0.025, 0.05, 0.075, 0.10, 0.15 and 0.20) was prepared using the sol-gel route in the morphotropic phase boundary (MPB) region. The X-ray diffraction data revealed the formation of both rhombohedral and tetragonal structures. The microstructural properties of the compounds were examined through the scanning electron microscopy (SEM) technique. The impedance spectroscopy and conductivity spectroscopy were carried out over a wide range of temperatures (RT–400°C) and frequencies (100 Hz–2 MHz) to investigate the grain and grain boundary effect on the electrical properties of PZTFx. The complex impedance analysis data have been presented in the Nyquist plot which is used to identify the corresponding equivalent circuit and fundamental circuit parameters. Cole– Cole plots indicate Debye-type dielectric relaxation and the grain boundaries resistance is dominant at room temperature. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR) character of PZTFx ceramics. The dielectric properties of (PZTFx) ceramics as a function of temperature are studied and displayed a resonance phenomenon for all samples. Temperature-dependent conductivity behavior indicated an Arrhenius type of thermally activated process in the low-temperature region. Activation energy has been calculated from the temperature-dependent DC electrical conductivity measurements for all the samples.

Development of Bioimpedance Spectroscopy Technology in Medical Decision Support Systems

The purpose of research – development of bioimpedance spectroscopy methods to develop on their basis objective and realistically accessible criteria for assessing the severity and prognosis of diseases, as well as evaluating the effectiveness of treatment methods, developing criteria for the use of conservative therapy options and surgical interventions in severe patients.Methods. The proposed method involves the use of a recurrent modified Voigt model as a biomaterial segment impedance model. For each model of a biomaterial segment, a Cole plot is plotted in a given frequency range. At the stage of determining the parameters of each of the models, a recurrent procedure is performed, which is the solution of systems of nonlinear equations, starting from one link of the Voight model with a subsequent increase in their number at each iteration step, until the value of the approximation error by the Voight model of the Cole experimental plot reaches allowed value.Results. As a result of the study, fundamentally new results have been obtained that allow creating intelligent decision support systems for diagnosing socially significant diseases. A bioimpedance analysis model based on multifrequency bioimpedance measurement has been created, which makes it possible to decompose the biomaterial impedance into structural elements, on the basis of which to determine descriptors for neural network classifiers of medical risk. In the work, an analysis of classifier errors was carried out in classifying the risk of acute destructive pancreatitis, which showed that the maximum value of the quality indicators of various classifier models was 78%, the minimum was 62%, demonstrating close values to the quality indicators of the ultrasound diagnostic method.Conclusion. The use of multifrequency sensing and modified Voight models in neural network classifiers of medical risk makes it possible to build clinical decision support systems for diagnosing socially significant diseases, as well as the ability to improve classification quality indicators and expand the functionality of intelligent medical decision-making systems.

A Bio-Electrochemical Calculation Model for Color Decline Kinetics of Bruised “Shine Muscat” Fruit During Storage

Physical damage of fruits and vegetables during distribution accelerate their decline in quality during storage. This study was aimed to analyze the quality degradation that takes injuries into consideration by using estimation models. Estimation models for bruised “Shine Muscat” grapes during storage were investigated based on bio-electrochemical theory. An electrical indicator, LTO, defined as the length from the origin of the coordinate at the top of the circular arc of the Cole−Cole plot, was demonstrated to effectively quantify the degree of a bruise with high accuracy (r2 > 99). The color-change kinetics constant increased as LTO decreased, and a strong correlation was confirmed between these two parameters (p < 0.01). These results demonstrate that the LTO parameter can be used to characterize physical damage incurred by the fruit, and it may be used as an injury parameter to calculate their color-change kinetics constant during storage after physical damage.

On the Correlation of Rheology and Morphology of Bimodal Polypropylene Reactor Blends Synthesized by Homogeneous Binary Metallocene/Metallocene Catalysts

ABSTRACTIn this study, morphological and rheological characteristics of bimodal polypropylene reactor blends synthesized by binary catalysts based on I: rac-Me2Si(2-Me-4-PhInd)2ZrCl2 and II: (2-PhInd)2ZrCl2 at different molar ratios were investigated. Gel permeation chromatography, scanning electron microscopy, and rheometry analysis were performed to evaluate the effect of molar ratio of catalyst II, responsible for the formation of elastomeric stereoblock polypropylene with low molecular weight, to catalyst I, responsible for production of high molecular weight isotactic (i) polypropylene, on the molecular weight, molecular weight distribution, morphological characteristics and rheological behavior of the synthesized products. The gel permeation chromatography results indicated that once a hybrid of the two catalysts is used, a broad and bimodal molecular weight distribution would be obtained, and the molar ratio of the catalysts governs the values of molecular weight and molecular weight distribution. 13C NMR results suggest that the different polypropylene tacticity resulting from the two catalysts (stereoblock vs. isotactic) is hardly influenced using a binary system. The effect of molecular weight enhancement and molecular weight distribution broadening was confirmed through the linear rheological data (G′ at lower frequencies, crossover modulus and crossover frequency) due to the impeded molecular motions of chains with high molecular weights which play an important role in the elasticity of chains. The zero shear rate viscosity and relaxation time, determined by fitting the Carreau–Yasuda model, are in great conformity with the experimental data at low-frequency region. Likewise, the miscibility and increased level of heterogeneity of microstructure, which is a result of changing the molar ratios of catalysts II/I, are confirmed through the Cole–Cole and Han plots and were further corroborated through the obtained scanning electron microscopy results.

Circadian variation of extracellular and intracellular resistance of the leg, arm, and trunk in healthy humans: a segmental bioimpedance spectroscopy study

Objective. The aim of the current study was to examine circadian variation of segmental resistance using segmental bioimpedance spectroscopy (BIS). Approach. Eight healthy men participated, and BIS was used to measure the resistance of the whole body (wrist-to-ankle model), and the arm, trunk, and leg every 2 h from 0700 to 2300 (nine points). Circumferences of the forearm, upper arm, thigh, and lower leg were also measured. Subjects consumed breakfast (0730), lunch (1130), and dinner (1930) ad libitum. Resistance of the extracellular and intracellular components (Re and Ri, respectively) was calculated from the Cole plot. Main results. Re of the arm increased at 1900 and 2100 compared with the value at 0700 (P < 0.05). Re and Ri of the leg decreased continuously toward the end of the day compared with the values at 0700 (P < 0.05). The lower leg circumference increased at 1700, 1900, and 2100 compared with the value at 0700 (P < 0.05). Significance. Resistance in the arm and leg show different circadian variation, which is probably associated with a systemic response to meals and body water redistribution between segments affected by gravity.

Aquifer Detection and Characterisation Using Material Balance: A Case Study of Reservoirs A, B, C and D

Oil and gas production needs energy, sufficient enough to drive the produced hydrocarbon to the surface of the well. Usually some of this required energy is supplied by nature. The hydrocarbon fluids are under pressure because of their depth. The gas and water in petroleum reservoirs under pressure are the two main sources that help move oil to the well bore and sometimes up to the surface. Depending on the original characteristics of hydrocarbon reservoirs, the type of drive energy is different. The material balance equation has been a very useful tool in analyzing these mechanisms. If none of the terms in the material balance equation can be neglected, then the reservoir can be described as having a combination drive in which all possible sources of energy contribute a significant part in producing the reservoir fluids, and determining the primary recovery factor. For this to happen, the water must be produced from an aquifer. The aquifer water expands slightly, displacing the oil or gas from the reservoir towards the borehole as pressure drops around the borehole. Most literatures have been able to call attention to the analysis of strong and partial water drive. This study was able to bring to light the aquifer characteristics based on weak water drives. Knowledge of the cumulative water influx is also important to the reservoir engineer. This study also goes ahead to add to aquifer detection and characterization, the cumulative water influx of each reservoir. The whole process entailed analyzing reservoirs A,B,C and D using the method proposed by Cole and Campbell. The plots showed a weak water drive for all reservoirs. The water influx for all the reservoirs were calculated and results obtained. The Cole and Campbell plots were proven to be more accurate method of detecting and characterizing aquifer and water drive strength.

Dilational Properties of Anionic Gemini Surfactants with Polyoxyethylene Spacers at Water−Air and Water−Decane Interfaces

The dilational properties of anionic gemini surfactants (oligooxa)-alpha,omega-bis(m-octylbenzene sulfonate) (C(8)E(x)C(8)) with polyoxyethylene spacers at the water-air and water-decane interfaces were investigated via the oscillating barriers method. The influences of oscillating frequency and bulk concentration on dilational properties were explored. The interfacial tension relaxation method was employed to obtain dilational parameters in a reasonably broad frequency range. The experimental results show that the number of ethylene oxide groups is one of the principal factors to control the nature of the interfacial film. With an increase of ethylene oxide groups, the dilational modulus of C(8)E(8)C(8) shows two maxima with the increasing concentration. Furthermore, the dilational moduli at the water-decane interface are remarkably lower than those at the water-air interface for C(8)E(1)C(8) and C(8)E(4)C(8), while the dilational modulus at the water-decane interface is close to that at the water-air interface for C(8)E(8)C(8), which indicates that the structure of the adsorption sublayer plays a more important role. Possible schematic diagrams of adsorbed molecules with different polyoxyethylene spacers at the water-air and water-decane interfaces are proposed. The results of relaxation experiments and Cole-Cole plots can support our provided mechanism strongly.

Direct Electron Transfer of Thiol-Derivatized Tetraphenylporphyrin Assembled on Gold Electrodes in an Aqueous Solution

Self-assembled monolayers (SAMs) of thiol-derivatized tetraphenylporphyrin (SH-TPP) and cobalt tetraphenylporphyrin (SH-CoTPP) have been prepared to examine the structure and direct electron transfer (ET) on a gold electrode in an aqueous solution. The cyclic voltammetry peaks of the porphyrin were obviously observed in aqueous solution. An interesting phenomenon was that direct ET cannot occur in phosphate-buffered solutions when a highly oriented and tightly packed monolayer is in existence, but the relatively low-density SH-TPP SAMs exhibited good electrochemical response. The electron transfer rate constants were obtained from the impedance spectra (Cole−Cole plot), upon application of different biasing potentials to the modified electrode. We propose a new kinetic model of the ET processes of SAMs of thiol-derivatized porphyrin and apply the density functional theory (DFT) to study the ET of porphyrin molecules on Au surfaces.

Crystal chemical and dielectric properties of Pb0.5(5-x)LaxNb5-xFexO15system with “tetragonal tungsten bronze” structural type

The lanthanum-lead and iron-niobium coupled substitution in PbNb 2 O 6 have allowed to isolate new materials of a general formula Pb 0.5(5-x) La x Nb 5-x Fe x O 15 crystallising with the tetragonal tungsten bronze structural type. The resulting influence on the lattice parameters, the ferroelectric Curie temperature and Cole - Cole plots are presented. A typical ferroelectric - paraelectric behaviour occurs in the composition range 0 ≤ x ≤ 0.33 while, a relaxor behaviour is observed in the composition range 0.33 < x < 1.

Electrical Conduction in Polycrystalline CVD Diamond: Temperature Dependent Impedance Measurements

In this paper, we report the first measurement of impedance on freestanding diamond films from 0.1 Hz to 10 MHz up to 300 °C. A wide range of CVD materials have been investigated, but here we concentrate on ‘black’ diamond grown by MWPECVD. The Cole–Cole (Z′ via Z″) plots are well fitted to a RC parallel circuit model and the equivalent resistance and capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 kΩ at 300 °C, with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 102 pF up to 300 °C, suggesting that the diamond grain boundaries are dominating the conduction. At 400 °C, the impedance at low frequencies shows a linear tail, which can be explained that the ac polarization of diamond/Au interface occurs.

Measurement of the Rate of Adsorption of Electroactive Cytochrome c to Modified Gold Electrodes by Electrochemical Impedance Spectroscopy

The electrochemistry of a system containing a surface-confined electroactive species is characterized by electrochemical impedance spectroscopy, and the results are displayed on a Cole−Cole plot. The rate of adsorption of electroactive horse-heart cytochrome c to a carboxythiol-modified gold electrode is experimentally monitored by continuously measuring the change in the magnitude of the pseudocapacitance, which is directly proportional to the amount of adsorbed protein. The time dependence of the adsorption of cytochrome c to the thiol-modified gold electrode shows a significant period of diffusion-controlled behavior. Limitations on the frequency of measurement are outlined in relationship to the magnitude of the standard rate constant of the electron-transfer reaction.

Simultaneous Observation of Coherent GaSb-like and AlSb-like Longitudinal Optical Phonons in GaSb/AlSb Superlattices

We have investigated coherent longitudinal optical (LO) phonons in GaSb/AlSb superlattices. The coherent AlSb-like LO phonon in the barrier layer and the coherent GaSb-like LO phonon in the well layer have been simultaneously observed. The GaSb-like LO phonon exhibits a cosine-type oscillation, which is the dominant signal. We have analyzed the initial phase of the AlSb-like LO phonon by plotting the imaginary part of the Fourier-transform components as a function of the real part, the so-called Cole–Cole's plot. We have found from this plot that the difference in the initial phase between the GaSb-like and AlSb-like LO phonons is about 90 degrees: The AlSb-like LO phonon has a sine-type oscillation. This difference in the initial phase indicates the difference in the generation mechanism between the coherent GaSb-like and AlSb-like LO phonons. We discuss the generation mechanism based on some proposed models.

Change in Viscoelastic Behaviors Due to Phase Transition of the Assembly Comprising Cetyltrimethylammonium Chloride/Cetyl Alcohol/Water

The phase transition process of molecular assembly comprising cetyltrimethylammonium chloride (C16CA), cetyl alcohol (C16OH), and water was analyzed on the basis of dynamic viscoelasticity, mainly by using Cole−Cole plots. The assembly prepared at 75 °C showed onionlike multilamellar vesicles (0.2−5 μm in diameter) immediately after preparation but transformed on aging into a rosary network of vesicles and finally fused into lamellae via polyhedra. The dynamic modulus (G‘) of the assembly monotonically increased with frequency, while the loss modulus (G‘ ‘) showed 2 peaks. The change in the angle parameters (αL, αS) calculated from Cole−Cole plots indicate the long and short time relaxation mechanisms, corresponding to the network of coagulated vesicles and lamellae, respectively.

Extraction of electrical characteristics from pixels of multifrequency EIT images

Computer modelling has shown that electrical characteristics of individual pixels may be extracted from within multiple-frequency electrical impedance tomography (MFEIT) images formed using a reference data set obtained from a purely resistive, homogeneous medium. In some applications it is desirable to extract the electrical characteristics of individual pixels from images where a purely resistive, homogeneous reference data set is not available. One such application of the technique of MFEIT is to allow the acquisition of in vivo images using reference data sets obtained from a non-homogeneous medium with a reactive component. However, the reactive component of the reference data set introduces difficulties with the extraction of the true electrical characteristics from the image pixels. This study was a preliminary investigation of a technique to extract electrical parameters from multifrequency images when the reference data set has a reactive component. Unlike the situation in which a homogeneous, resistive data set is available, it is not possible to obtain the impedance and phase information directly from the image pixel values of the MFEIT images data set, as the phase of the reactive reference is not known. The method reported here to extract the electrical characteristics (the Cole - Cole plot) initially assumes that this phase angle is zero. With this assumption, an impedance spectrum can be directly extracted from the image set. To obtain the true Cole - Cole plot a correction must be applied to account for the inherent rotation of the extracted impedance spectrum about the origin, which is a result of the assumption. This work shows that the angle of rotation associated with the reactive component of the reference data set may be determined using a priori knowledge of the distribution of frequencies of the Cole - Cole plot. Using this angle of rotation, the true Cole - Cole plot can be obtained from the impedance spectrum extracted from the MFEIT image data set. The method was investigated using simulated data, both with and without noise, and also for image data obtained in vitro. The in vitro studies involved 32 logarithmically spaced frequencies from 4 kHz up to 1 MHz and demonstrated that differences between the true characteristics and those of the impedance spectrum were reduced significantly after application of the correction technique. The differences between the extracted parameters and the true values prior to correction were in the range from 16% to 70%. Following application of the correction technique the differences were reduced to less than 5%. The parameters obtained from the Cole - Cole plot may be useful as a characterization of the nature and health of the imaged tissues. Keywords: multifrequency EIT, tissue characterization, Cole - Cole plot

Dynamic Viscoelasticity of an Aqueous System of a Poly(ethylene oxide)−Poly(propylene oxide)−Poly(ethylene oxide) Triblock Copolymer during Gelation

Viscoelastic properties during thermo-induced gelation of a binary poloxamer (Pluronic F68)/water system have been determined by oscillatory shear and shear stress relaxation measurements. The polymer concentration has been kept constant at 35 wt %. A sol−gel transition is observed in the range 34−37 °C. The oscillatory shear data at temperatures around the gel temperature reveal a complex pattern of behavior. The results cannot be described by a single Maxwell element behavior as demonstrated by converting the data to Cole−Cole plots. Shear stress relaxation experiments show that the stress relaxation at the lowest temperatures of measurement (34 and 35 °C) can be described initially by a single exponential followed at longer times by a stretched exponential profile. At 36 °C and higher temperatures, a new relaxation mode in the form of a power law enters at intermediate times, between the exponential and stretched exponential domains. The power law part of the relaxation function has its maximum time wi...

Higher-order cumulants in the study of reorientational molecular motions

The relation between angular velocity and reorientational correlation functions gives the base to study reorientational molecular motion in terms of the angular velocity stochastic process (ω process) using a cumulant expansion. As ω process the process which satisfies the second order stochastic differential equation has been chosen ??? such a model the second and fourth cumulants have been ???. The influence of higher cumulants on the behav??? Cole plots is briefly discussed.

A self-consistent theory of rotational diffusion

The effect of long range Coulomb and dipolar forces on the collective tumbling of rigid linear dipoles is considered. It is shown that the Debye relaxation times are modified by the presence of these long range forces in important ways. Explicit expressions for these relaxation times are derived for polar and electrolyte solutions. It is shwon that for dense solutions there are significant deviations from the Debye semicircle in the Cole−Cole plot.

Cole and cole plots and distribution functions of decay times. A new general relation between α and Δ τ/τ0

physica status solidi (a)Volume 24, Issue 1 p. K19-K22 Short Note Cole and cole plots and distribution functions of decay times. A new general relation between α and Δ τ/τ0 A. Le Traon, A. Le Traon Laboratoire de Ferroélectricité, Faculté des Sciences de RennesSearch for more papers by this author A. Le Traon, A. Le Traon Laboratoire de Ferroélectricité, Faculté des Sciences de RennesSearch for more papers by this author First published: 16 July 1974 https://doi.org/10.1002/pssa.2210240141Citations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume24, Issue116 July 1974Pages K19-K22 RelatedInformation

Dielectric Anomaly of Ammonium Nitrate in Low Frequency Region

Dielectric measurements are made on a pressed sample of ammonium nitrate powder in the frequency region from 25 c/s to 50 kc/s. Two main dispersions are found, one in the extremely low frequency region, supposed to be the blocking space charge effect, and the other in the slightly high frequency region, represented fairly well by a circular are in the Cole plot. The activation energy of the dipole orientation related to the latter relaxation is estimated to be about 0.58 ev for the phase III. The phase changes (IV\(\rightleftarrows\)III\(\rightleftarrows\)II) give no significant effect on the nature of such abnormal dispersion in the qualitative point of view. A model based on the co-operative action of ion pairs which are connected to each other by hydrogen bonds, is proposed for the explanation of the mechanism of this low frequency dispersion. The dielectric constant of the phase II is much larger than that of the phase III even for the measurement at a high frequency. This fact suggests the existence of large anomaly at a frequency much higher than 50 kc/s. The co-operative orientation of NO 3 ions in the neighbouring cells are suggested as a possible model in this case.