Current IL Research Articles

Effects of sintering temperature on microstructure and varistor performances of ZnO-SrCO3-Co2O3 ceramics

Sintering temperature is decisive for optimizing the grain boundary environment to obtain the high performance ZnO based varistor ceramic. In this work, the impacts of sintering temperature on microstructure and electrical properties of ternary Zn-Sr-Co varistor were investigated. It was found that the distribution of Sr, the critical factor to form grain boundary, was heavily sensitive to sintering temperature. The considerable Sr ions precipitated at grain boundaries and formed the clusters of SrZnO2 while the sintering temperature increases from 1150 °C to 1190 °C. Besides, the precipitation of Sr led to the large segregation of Co at grain boundaries. The enrichment behavior of Sr and Co contributed to the optimization of grain boundaries, resulting in the enhanced barrier height. As a result, the excellent nonlinear current-voltage performances, i.e., the high nonlinear coefficient of 56.47 and the low leakage current density of 0.73 μA/cm2 were obtained in the ternary ZnO-SrCO3-Co2O3 varistor sintered at 1190 °C. However, the grain boundary environment would be destroyed by the excessive temperature of 1210 °C, resulting in the degradation of grain boundary barrier and especially a surge in the leakage current IL from 0.73 to 92.19 μA/cm2. In addition, varying sintering temperature has the important effects on impedance and dielectric properties of the ZnO-SrCO3-Co2O3 varistors. The findings provide new perspectives for developing the high-performance ternary ZnO-SrCO3-Co2O3 varistor ceramics by optimizing the initial grain boundary environment at different sintering temperatures.

Impacts of SiO2 on phase composition, microstructure, and electrical properties of ZnO-SrCO3-Co2O3 ceramics

ZnO-SrCO3-Co2O3-SiO2 varistor ceramics were fabricated using the solid state method. Structural, morphological characterizations and varistor characteristics of samples were systematically studied. Average grain size is gradually reduced from 13.74 to 6.67 μm, resulting in a simultaneous increase of breakdown gradient E1 mA from 157.14 to 339.29 V mm−1. An increase of doping amount of SiO2 from 0 to 0.50 mol% contributes to the positive influences on double Schottky barrier of ZnO-SrCO3-Co2O3 varistors. The sample doped by 0.50 mol% SiO2 exhibits the highest height of double Schottky barrier φB of 2.99 eV resulting in the high nonlinear coefficient α equal to 76.83 and small value of leakage current density IL less than 0.29 μA cm−2 among the samples, which may be attributed to the solid solution reactions of SiO2 and Co2O3 in grain boundaries. The fabrication of ZnO-SrCO3-Co2O3-SiO2 represents the low-cost, sustainable development and environmental friendliness, providing a high performance candidate material for dominant ZnO-Bi2O3 based varistor ceramics.

Effect of Bi-Er-O addition on the electrical properties of ZnBiCoMnSb based varistor

In order to restrain the breakdown voltage gradient E1 mA at a low level and simultaneously improve nonlinear coefficient α, the rare earth element Er was doped into ZnBiCoMnSb based varistor ceramic in the form of Bi-Er-O phase. As a result, the excellent electrical performances including low E1 mA of 190 V/mm, high α of 55.6 as well as low leakage current IL of 2.5 μA/cm2 are obtained in 3 wt% Bi-Er-O phase modified ZnBiCoMnSb based varistor ceramic. It is found that the concentration of Er at grain boundaries is slightly higher than that in ZnO grains, while it is uniformly distributed throughout the bulk ceramic. This characteristic of element distribution mainly contributes to the enhancement of α by forming interface state densities and deep bulk traps at grain boundaries, rather than E1 mA. The reported herein strategy to restrain E1 mA and improve α at the same time on ZnBiCoMnSb based varistor ceramic can act as a reference for further fabrication of low-E1 mA varistor ceramics with excellent nonlinear performances by rare earth elements doping.

The effect of Gd on the microstructure and electrochemical properties of Mg-Ni-based alloys

The Mg-Ni-based alloys have been extensively investigated as negative electrode materials in Nickel-Metal Hydride (Ni-MH) batteries. In this work, two Mg-Ni-based samples (Mg71Ni29 and Mg72.6Ni25.3Gd1.1) were prepared by means of melting. The X-ray diffraction (XRD), scanning electron microscope (SEM), galvanostatic charging/ discharging and other electrochemical measurements were used for the investigation. The results show that the Mg71Ni29 and Mg72.6Ni25.3Gd1.1 alloys include the characteristic peaks of Mg2Ni and the less strong characteristic peaks of Mg and MgNi2 phases. The diffraction peak of the major phase Mg2Ni of the Mg72.6Ni25.3Gd1.1 alloy is shifted to a small angle and its unit cell volume increases. With the addition of Gd, the alloy electrodes exhibits better cycling stability. After 50 charge/ discharge cycles, the capacity retention rate of the alloy electrode increase from 16% (Mg71Ni29) to 22% (Mg72.6Ni25.3Gd1.1). However, the maximum discharge capacity of the alloy electrode decrease from 134.3 mAh/g (Mg71Ni29) to 91.9 mAh/g (Mg72.6Ni25.3Gd1.1). The Mg72.6Ni25.3Gd1.1 alloy possess lower limiting current density IL and exhibit relatively high corrosion resistance against the alkaline solution. After Gd doping, the charge transfer capacity of the Mg72.6Ni25.3Gd1.1 alloy surface is increased.

Low temperature preparation of YSZ-based thin-film limiting current type oxygen sensor

Oxygen sensors based on YSZ solid electrolyte thin films have great application prospects due to their advantages in miniaturization and integration. Here, we report the gas sensing performance of Pt/YSZ/Pt oxygen gas sensors with low preparing temperatures. YSZ thin films with (200) preferred orientation have been prepared by room temperature RF magnetron sputtering combined with annealing at a temperature of 650 °C. The 700 nm-thick YSZ films exhibit an obvious limiting current platform, and the limiting current IL shows a linear dependence on oxygen concentration X(O2) (in the range of 6%–21%). Moreover, the devices with 700 nm-thick YSZ films worked well at the temperature range from 500 to 650 °C, and a linear relationship between logIL and 1000/T has been observed. These results demonstrate that YSZ thin films prepared by low temperature magnetron sputtering combined with the annealing process can reduce the working temperature.

Environmental Autonomy

Abstract This article aims to get a new brand start to the autonomy debate by examining environmental autonomy (ea) as a new concept under international law (il). In this respect, firstly, it focuses on establishing why such a notion is needed, where the idea comes from, so, on which basis the article’s analysis has been built. Secondly, to conceptualise ea in legal terms, it makes research on two sub-debates involving the principle of self-determination and nonhuman rights approach. Finally, it concludes that although there is no tangible certain legal basis to apply such a concept under current il other than the terms of indigenous rights; developments in recent decades show that, ea debate, testing the boundaries of law, might truly have the potential to the development of literature beyond the anthropocentric paradigms; but also underlines the need for further work on its potential legal framework under il.

Hysteresis Based Quasi Fixed Frequency Current Control of Single Phase Full Bridge Grid Integrated Voltage Source Inverter

The traditional Fixed Band Hysteresis Current Control (FB-HCC) though being widely used for the current control of grid integrated voltage source inverter (GI-VSI), has the drawback of variable switching frequency. To overcome this drawback, Complex Programmable Logic Device (CPLD) based switching scheme is proposed in this paper. The proposed method calls for a single reference wave and the control concept is to terminate the rising and falling inductor current (iL) either by the comparator or by the CPLD, based on the nature of its slope. Termination of the iL with steeper slope by the comparator ensures lower current ripple, whereas the CPLD ensures constant switching frequency (fsw). However, the iL obtained with the proposed logic has a DC offset, which is corrected by modifying the reference. The basic concept, switching logic, and reference correction are thoroughly detailed. MATLAB/Simulink results are included to verify the proposed concept. The constant frequency operation of the proposed method is also validated in a 2 kW, 230 V, 50 Hz GI-VSI prototype.

Super-capacitor energy storage system to recuperate regenerative braking energy in elevator operation of high buildings

<span>In operating phases of elevators, accelerating, braking modes occur frequently, so braking energy recuperation of elevators has contributed considerably to decrease the total electric energy consumption for operating elevators in multi-floor buildings. In this paper, the supercapacitor energy storage system is used to recover regenerative braking energy of elevators when they operate down full-load and up no-load, reducing fluctuation of voltage on DC bus as well. Therefore, super-capacitor energy storage system (SCESS) will be parallel with line utility to recuperate regenerative braking energy in braking phase and support energy for acceleration phase. The surplus energy will be stored in the supercapacitors thanks to a DC-DC converter capable of exchanging energy bidirectionally in buck/boost modes, and designing control strategy including two control loops. Inner loop-current loop: controlling charge/discharge process of supercapacitors by current iL complying with operation characteristic of elevator; Outer loop-voltage loop: managing UDC-link at a fixed value. Simulation results with elevator system of the ten-floor building, Hanoi, Vietnam installed SCESS have been verified on MATLAB Simulink, SimPowerSystem with saving energy level about 30%.</span>

Schottky diode temperature sensor for pressure sensor

The small silicon chip of Schottky diode (0.8 × 0.8 × 0.4 mm3) with planar arrangement of electrodes (chip PSD) as temperature sensor, which functions under the operating conditions of pressure sensor, was developed. The forward current-voltage I–V characteristic of chip PSD is determined by potential barrier between Mo and n-Si (ND = 3 × 1015 cm−3). Forward voltage UF = 208 ± 6 mV and temperature coefficient TC = -1.635 ± 0.015 mV/°C (with linearity kT < 0.4 % for temperature range of -65 to +85 °C) at supply current IF =1 mA is achieved. The reverse I–V characteristic has high breakdown voltage UBR > 85 V and low leakage current IL < 5 μA at 25 °C and IL < 130 μA at 85 °C (UR = 20 V) because chip PSD contains the structure of two p-type guard rings along the anode perimeter. The application of PSD chip for wider temperature range from -65 to +115 °C is proved. The separate chip PSD of temperature sensor located at a distance of less than 1.5 mm from the pressure sensor chip. The PSD chip transmits input data for temperature compensation of pressure sensor errors by ASIC and for direct temperature measurement.

Synthesis and evaluation of nonionic surfactants based on dimethylaminoethylamine: Electrochemical investigation and theoretical modeling as inhibitors during electropolishing in-ortho-phosphoric acid

Three non-ionic surfactants had synthesized through one simple direct reaction between N, N-dimethylethylenediamine and three fatty acids: octanoic, palmitic and oleic acid. The chemical structures of the synthesized non-ionic surfactants had been confirmed by FTIR &1HNMR spectroscopy. The surface and thermodynamic behavior of the surfactant were determined at different temperatures based on surface tension (γ) measurments. The critical micelle concentration (CMC) is dependent on both of the hydrophobic chain length and solution temperature. The change in free energy of micellization (∆G°mic) and adsorption (∆G°ads) referring that the synthesized surfactants favor adsorption at interfaces than constructing a micelle. The performance of the synthesized surfactants on the dissolution behavior of carbon steel in 8 M H3PO4 acid have been investigated at temperature range 15 to 45 °C via weight loss and polarization measurements. The dissolution rate (limiting current IL) decreases with increasing the surfactants concentrations confirming a mass transport-controlled process and a salt-film mechanism. Polarization curves showed that the prepared surfactants are good anodic inhibitors and the adsorption on the carbon steel surface obeys the Langmuir isotherm. The examining the surface morphology, topography and brightness of the carbon steel in a 8 M H3PO4 containing the synthesized surfactants using scanning electron microscope (SEM), atomic force microscope (AFM) and gloss meter, disclosed the adsorption of the prepared inhibitors surfactant on the steel surface. The data obtained from theoretical calculations support empirical results.

Modeling of three-phase inverter power supply system in Simulink

A model of a three-phase electronic converter of electric energy for an autonomous power supply system has been studied. The objective is measuring the percentage of the higher harmonics in the output of the three-phase inverter voltage and the effect of adding a passive selective Notch filters. Their inclusion in the output circuit creates a model of the system with improved electromagnetic compatibility, and hence an increased power factor and efficiency. A virtual architecture of the three-phase inverter power supply system has been developed in Matlab - Simulink software environment. The invertor is built of separate functional blocks simulating the components that can be embedded in a real project. The schematic diagram includes three-phase symmetric loads with three-phase filters models. The main operation modes of the invertor are modeled and the effects of adding three-phase filters to the output circuit after the voltage inverter are analyzed. From the pulse with modulation simulation, the frequency spectrum for the output current IL and voltage UL has been synthesized.

Escalation portion of phase II study to evaluate the safety, pharmacokinetics, and clinical activity of the PI3K/mTOR inhibitor paxalisib (GDC-0084) in glioblastoma (GBM) with unmethylated O6-methylguanine-methyltransferase (MGMT) promotor status.

2550 Background: Paxalisib (previously GDC-0084) is a potent, oral, selective, brain-penetrant, small molecule inhibitor of class I phosphoinositide 3-kinase and mammalian target of rapamycin. The PI3K pathway is upregulated in ~85% of GBM cases and paxalisib has shown efficacy in preclinical models. A phase I study (NCT01547546) investigated paxalisib dosed once daily in 47 patients with recurrent high-grade gliomas and established a maximum tolerated dose (MTD) of 45mg once daily. The current phase Il study aims to explore the safety, tolerability, and clinical activity of paxalisib in newly diagnosed GBM and an unmethylated MGMT promotor following surgery and temozolomide chemoradiation per Stupp regimen. Methods: Part 1 of this study is an open-label, dose-escalation phase to assess the safety, tolerability and MTD. Dose-escalation started at 60mg and progressed in 15mg increments using a 3+3 design. Part 2 is an expansion cohort recruiting 20 patients randomized to administration in fed or fasted states at the MTD. Results: Part 1 is complete and reported here. Nine patients were recruited and an MTD of 60mg was determined. DLTs were hyperglycemia and oral mucositis. AEs were generally reversible and consistent with the PI3K inhibitor class with the most common events were rash, oral mucositis, and fatigue. PK at the MTD was broadly consistent with the data published for the phase 1 study. For eight response-evaluable patients in Part I the median progression-free survival (PFS) was 8.4 months, and 25% of patients remained progression free after 15 months of follow-up. Part 2 is ongoing. Conclusions: A higher MTD of 60mg was identified in newly diagnosed GBM with unmethylated MGMT promotor status than the 45mg MTD previously identified in recurrent high-grade glioma. An encouraging PFS signal is described in this poor-prognosis, unmethylated MGMT patient population. Clinical trial information: NCT03522298 .

Effects of dispersant content and pH on dispersion of suspension, microstructures and electrical properties of ZnO varistors

This article systematically studies the relationship between the dispersity of the mixed suspension, the microstructures and the electrical properties of the ZnO varistors by adjusting the dispersant content and the pH value. The suspension dispersity was measured by viscosity, zeta potential, particle size distribution and TEM observation. The structure of the as-prepared ZnO varistors was characterized by XRD and SEM. The electrical properties were investigated by testing E-J characteristics, breakdown voltage, leakage current, nonlinear coefficient, 8/20 μs waveform current impulse and accelerated aging performance. When the suspension reached the best dispersion condition of 0.3 wt% dispersant and the original pH value, the ZnO varistors had optimum electrical properties: breakdown voltage gradient of 299.95 V mm−1, leakage current IL of 0.33 μA, voltage ratio U5kA/U1mA of 1.686, nonlinear coefficient of 46.71, and a downward trend of power consumption in the accelerated aging test.

Effect of Ni2O3 Doping on the Electrical Properties and Intrinsic Defect Concentration of ZnO Varistor Ceramics

With the development of high voltage transmission, there is an urgent need to develop ZnO varistor ceramics with high anti-aging properties. The key is to manipulate the intrinsic defect concentration of ZnO varistor ceramics precisely. In this paper, ZnO varistor ceramics doped with different contents of Ni2O3 are taken to study the relationship between the microstructure and electrical properties, and the effect of ZnO varistor ceramics doped with different contents on intrinsic defect concentration is also considered. The results show that, best electrical performance is shown when the content of Ni2O3 is 1.2mol%, the electrical breakdown field E1mA is 356 V/mm, the nonlinear coefficient reaches 32, and the leakage current IL is 3.4 . While the amount of the doped Ni2O3 is more 0.8mol%, a new phase of Co2Cr5Sb5O4 phase is observed from X-ray diffraction. The SEM micrographs showed that the average grain size decreased monotonously from 14.56 m to 5.73 m with the amount of the doped Ni2O3 increased. According to the results of dielectric spectroscopy, the intrinsic defect concentration increased with the contents of the doped Ni2O3 increased. The increase of Zinc interstitial is much greater than that of Oxygen vacancies, which is harmful to Long-term aging characteristics of ZnO varistor ceramics.

Gadolinium as an Inhibitor of Ionic Currents in Isolated Rat Ventricular Cardiomyocytes.

The whole-cell patch-clamp technique was used to examine the effect of gadolinium Gd3+ (a non-specific blocker of mechanically gated current IMGCh, a component of late current IL) on ionic currents in insolated rat ventricular cardiomyocytes alone and in combination with the blockers of L-type calcium currents (ICaL) nifedipine (10 μM) or verapamil (1 μM). In K+in/K+out or Cs+in/Cs+out media, blockade of ICaL produced no effect on IL at negative potentials, but inhibited IL at positive ones. In K+in/K+out medium, Gd3+ (5 μM) decreased the net persistent current (Inp) at -45 mV from 198.6±6.4 to 96.7±9.5 pA over 15 min. Gd3+ alone or in combination with ICaL blockers shifted the reversal potential of IL to more negative values. At negative potentials, Gd3+ decreased IK1 and inward current including IMGCh. At positive potentials, Gd3+ alone or in combination with ICaL blockers decreased IL. When applied for 15 min in Cs+in/Cs+out medium at -45 mV, Gd3+ produced no effect on net current and inward and outward components of IL. Thus, Gd3+ can be viewed as a specific blocker of IMGCh only in Cs+ medium.

Mismatch Loss in Bifacial Modules Due to Nonuniform Illumination in 1-D Tracking Systems

We apply ray tracing to compute the light-generated current IL within each solar cell of a bifacial tracking module, and circuit modeling to quantify how the spatial variability in $I_{L}$ (i.e., current mismatch) reduces the module's output power P MP. We find that 10 million rays are required to accurately map $I_{L}$ for a central module in a photovoltaic (PV) system at a given insolation condition. The relative reduction in P MP is found to be 1) greatest in the middle of the day for sunny conditions, 2) independent of time for very cloudy conditions, 3) higher for edge modules than central modules, 4) higher for one-high portrait configurations than for two-high, and 5) higher when the ground albedo is higher. We trace 2 billion rays on 2000 parallel cores to solve a module's annual energy yield for a system located at Golden CO with a sandy soil. The yield reduction in a one-high configuration due to nonuniform illumination is 0.23% for a central module and 0.35% for an edge module. Thus, in this example, mismatch loss due to nonuniform illumination within an individual tracking module is relatively low, despite the rear of the module being shaded by a torque tube.

Investigation of the microstructure and the thermodynamic and kinetic properties of ball-milled CeMg12-type composite materials as hydrogen storage materials

In order to improve the electrochemical discharge and kinetics of CeMg12-type hydrogen storage materials, ball-milling was used and Ni was added to fabricate alloying materials with a nanocrystalline and amorphous structure. The phase composition and crystalline structure were characterized by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The electrochemical discharge performances were characterized by determining the discharge capacity and electrochemical cycling stability. High-rate dischargeability (HRD), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization were utilized to investigate the changes in electrochemical kinetics. The results indicate that the addition of Ni significantly enhances the glass-forming ability of the alloy samples during ball milling, which significantly improves the electrochemical cycling stability of the alloy samples. The maximum discharge capacity of the ball-milled composites monotonously increases from 41.7mAh/g to 485.5 mAh/g with an increment in the Ni content from 50 wt>% to 200 wt%. An increase in the Ni content results in a considerable reduction in the enthalpy (ΔH) from −106.2 kJ/molto −43.1 kJ/mol and in the entropy (ΔS) from −350.73 kJ/mol/K to −22.49 kJ/mol/K. The addition of Ni reduces the stability of the hydride and improves the electrochemical discharge capacity. With regard to the electrochemical kinetics, the addition of Ni can diminish the activation energy of the alloy samples from74.02 kJ/mol to 33.28 kJ/mol with an increase in the Ni content from 50 wt% to 200 wt%, which speeds up the charge-transfer reaction on the surface. The addition of Ni accelerates the hydrogen diffusion rate(which is related to the limiting current density IL) inside the alloy particles. These effects improve the electrochemical kinetics.

Varistor behavior in a ternary system based on SnO2 doped with a hexavalent donor: SnO2-MnO2-WO3

Pentavalent metals have been used as donors in tin dioxide, giving it varistor characteristics when associated with densifiers such as CoO or MnO2. However, attempts to obtain varistor behavior in SnO2-based ternary systems using hexavalent donors such as W6+ have been unsuccessful to date, leading to typical linear behavior. Here it is shown that one can achieve nonlinear behavior in this kind of system, given a suitable choice of densifier (MnO2). In order to get insights into the role of WO3 content on the potential barriers responsible for varistor properties, a combination of experimental and theoretical techniques was used. Measurements revealed two minor but relevant phases, Mn3O4, and MnWO4, whose presence was explained by theoretical calculations and whose amount was estimated as a function of WO3 content. This estimate revealed a correlation between Mn3O4 amount and varistor properties, interpreted with basis on Mn defects at SnO2/Mn3O4 interfaces. WO3 content was varied to optimize the varistor properties, resulting in nonlinear coefficient α≈ 6, breakdown electric field Eb> 10 kV/cm and leakage current Il≈ 200 μA. This finding is expected to stimulate further investigations on SnO2-based ternary systems containing hexavalent oxides, especially using other densifiers, such as CoO.

Built-in electric field promotes photoexcitation separation and depletion of most carriers in TiO2:C UV detectors

TiO2 has been widely used in ultraviolet (UV) photodetectors, but due to the large number of structural defects and strong band-to-band recombination of the exciton in TiO2, the devices usually have large dark current (Id) and low light current (Il), which seriously reduces the sensitivity and responsivity (R) of the TiO2 based devices. In this work, carbon (C) quantum dots (QDs) are introduced into TiO2 film to ameliorate these issues. Due to the difference of work function between TiO2 nanoparticles and C QDs, the built-in electric field (Ebi) can be formed, which effectively facilitates the photogenerated exciton dissociation in the TiO2 film under UV illumination. Meanwhile, the constructed depletion region in dark reduces the majority carrier density, thus decreasing the Id of the photodetector. Moreover, the Ebi and depletion region will also contribute to the faster charge collection under UV illumination and recombination of the electron in dark, which is beneficial for the improved response/recovery speed of the device.

Determining "Apparent" Diffusion of Electrons through a Nafion Membrane Using Hydrodynamic Voltammetry

Nafion is used extensively as a proton exchange membrane in PEM fuel cells. The membrane must be hydrated in order to function properly as an electrolyte and as a physical separation barrier between the anode and the cathode. In this project, potassium ferricyanide is added to the hydrating electrolyte solution and is shown to incorporate into the Nafion membrane. By using hydrodynamic voltammetry, the ferricyanide redox signals can be used as a diagnostic and an investigative tool to study the integrity and swelling properties of the Nafion membrane. When ferricyanide is absent from the hydrating solution, but present in the bulk electrolyte solution during the hydrodynamic voltammetry experiments, the signals produced (or lack thereof) can be used as a diagnostic tool for the physical integrity of the membrane. When ferricyanide is allowed to incorporate into the membrane, the properties of the hydrated membrane can be investigated. An new equation, known as the Tedford equation, was derived to determine the diffusion coefficient of the analyte in the bulk solution and an apparent diffusion of electrons within the membrane itself. The Tedford equation accounts for the dependence on the rotation rate as well as known membrane properties such as thickness and the concentration of the analyte incorporated into the membrane from the bulk solution during hydration.For a bare rotating disk electrode, the Levich equation can be used to determine the bulk diffusion coefficient (D) by plotting the diffusion limiting current (iL) against the square root of the rotation rate (ω). iL=0.62nFAD2/3 ν-1/6 C* ω1/2 (1) The slope is made up of the known variables where n is the number of electrons in the redox reaction, F is Faraday’s constant, A is the electroactive area of the electrode, ν is the kinematic viscosity of the solution, and C* is the concentration of the analyte in the bulk. The Dahms-Ruff equation can be used to determine the apparent diffusion coefficient of electrons (DE) and the current due to this apparent diffusion (iE).DE=D+kφ2 Cp* (π/4) (2) iE=(FADE Cp*)/δm (3) where k is the rate constant of the redox reaction, φ is the average distance between the redox centers in the membrane, Cp* is the total amount of analyte in the membrane, and δm is the membrane thickness. Equations 1 and 3 were combined to derive the Tedford equation in relation to the peak current (ip). ip=0.62nFAD2/3 v-1/6 ω1/2 (C*-Cm )+(nFADE Cm)/δ m (4) This equation can be used to determine the apparent diffusion coefficient of the electrons with the ferricyanide redox centers in the membrane. It can also be used to compare membranes with differing hydration times and possibly to study hydrating properties.