scholarly journals Combined Spectrophotometric— Electrochemical Impedance Imaging System for Biofilm Research

2005 ◽  
Vol 10 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Chirag Patel ◽  
Stanley Dunn ◽  
Paul Takhistov
Keyword(s):  
Electrochemical Impedance ◽  
Imaging System ◽  
Impedance Analysis ◽  
Low Frequencies ◽  
High Frequencies ◽  
Impedance Imaging ◽  
Noninvasive Analysis ◽  
A Cell ◽  
Computer Controlled ◽  
Automatic Scanning

We propose an automatic scanning microscope that is capable of analyzing the properties of the biofilm-associated cells by using optical and impedance spectroscopy. The operating principle of the instrument is based on measuring the electrical impedance of cell culture grown on a conductive substratum that is used as one of the electrodes. At low frequencies, the impedance analysis is capable of characterizing a biofilm at the macroscale, and at high frequencies it is capable of analyzing the peculiarities of a cell layer at the level of single microorganisms. The combination of these two techniques is sufficient to give a quantitative and structural composition of a biofilm at both levels. The developed instrument can be useful in the broad range of biofilmrelated research studies, providing the data for detailed, real-time, computer-controlled, noninvasive analysis of cell-to-cell and cell-to-surface interactions.

scholarly journals Further Understanding of Uncertainties in the Impedance Spectrum of the Polymer Electrolyte Fuel Cell due to Inductive Effects and Oxygen Diffusion Time Constant

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Samuel Cruz-Manzo ◽  
Keyword(s):  
Charge Transfer ◽  
Time Constant ◽  
Oxygen Diffusion ◽  
Electrochemical Impedance ◽  
Impedance Spectrum ◽  
Diffusion Time ◽  
Polymer Electrolyte Fuel Cell ◽  
Low Frequencies ◽  
High Frequencies ◽  
Eis Measurements

In this study, uncertainties during the assessment of the electrochemical impedance spectrum of the polymer electrolyte fuel cell (PEFC) attributed to inductive artefacts at high frequencies and inductive loops at low frequencies as well as oxygen diffusion time constant are discussed. A validated impedance model represented as an equivalent electrical circuit of a PEFC allowed the simulation of the effect of inductive artefacts, inductive loops and oxygen diffusion time constant on electrochemical impedance spectroscopy (EIS) measurements represented in the Nyquist plot. This study considers EIS measurements reported in previous studies and provides an insight into the EIS measurements with positive imaginary components at high frequencies attributed to the intrinsic inductance of the measurement cables during EIS tests and at low frequencies attributed to electrochemical mechanisms (e.g. side reactions with intermediate species) during PEFC operation. In addition, an overview of overlapping mechanisms (charge transfer and oxygen transport resistances during the oxygen reduction reaction) on the PEFC impedance spectrum attributed to oxygen diffusion across the cathode catalyst layer is presented. EIS measurements with positive imaginary components and with overlapping effects could yield to ambiguities when studying or relating electrochemical mechanisms (ion conduction, capacitance, charge transfer and mass transport resistances) of the PEFC through a defined single frequency or a single measured value represented in the Nyquist complex-impedance plot.

scholarly journals Performance of Photovoltaic Modules After an Accelerated Thermal Cycling Degradation Test

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Aramis Perez ◽  
Luis Gabriel Marin ◽  
Fernando Fuentes ◽  
Patricio Mendoza ◽  
Guillermo Jimenez ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Electrochemical Impedance ◽  
Low Frequencies ◽  
High Frequencies ◽  
Photovoltaic Modules ◽  
Pv Module ◽  
Pv Modules ◽  
Degradation Test ◽  
Accelerated Thermal Cycling ◽  
Eis Analysis

Typically, datasheets of photovoltaic (PV) modules state that the guaranteed power production remains constant for a certain period of time and after this point, a linear reduction begins reaching an estimated 80% of the original rated power. Moreover, literature reports that the degradation of PV modules reaches less than 1% per year. In this regard, after 20 years of operation a typical PV module will deliver approximately 20% less energy than a the beginning of its life. In this article, the results of an accelerated thermal cycling degradation test are compared to its brand new conditions. These results demonstrate that although the performance among the PV modules is variable when new, after the cycling test the performance of the degraded PV modules is similar. In this case, the power reduction of the degraded module varies from 1.4% up o 7.6% when compared to the initial condition. Furthermore, an Electrochemical Impedance Spectroscopy (EIS) analysis demonstrates that at high frequencies the results are practically the same regardless if the panel is new or degraded, but at low frequencies the variation of the impedance is notorious.

Characterizations of Synthetic 8mol% YSZ with Comparison to 3mol %YSZ for HT-SOFC

2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim
Keyword(s):  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Structural Information ◽  
Impedance Analysis ◽  
High Energy ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Powder Morphology ◽  
X Ray

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

2015 ◽  
Vol 804 ◽  
pp. 25-29 ◽  
Author(s):  
Wanlop Harnnarongchai ◽  
Kantima Chaochanchaikul
Keyword(s):  
Natural Rubber ◽  
Cell Size ◽  
Cell Morphology ◽  
Foam Cell ◽  
Adsorption Coefficient ◽  
Low Frequencies ◽  
Potassium Oleate ◽  
High Frequencies ◽  
Blowing Agent ◽  
Open Cell Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

Electrochemical Impedance Analysis of the Wear of Planographic Plates

CORROSION ◽  
1991 ◽  
Vol 47 (1) ◽  
pp. 67-73 ◽  
Author(s):  
M. W. Kendig ◽  
S. Breitweiser ◽  
E. Hudyma
Keyword(s):  
Electrochemical Impedance ◽  
Impedance Analysis

Hearing loss in diabetics

1993 ◽  
Vol 107 (3) ◽  
pp. 179-182 ◽  
Author(s):  
J. R. Cullen ◽  
M. J. Cinnamond
Keyword(s):  
Hearing Loss ◽  
Sensorineural Deafness ◽  
Insulin Dosage ◽  
Speech Discrimination ◽  
Low Frequencies ◽  
High Frequencies ◽  
History Of ◽  
Insulin Dependent ◽  
Stapedial Reflex ◽  
The Relationship

The relationship between diabetes and senbsorineural hearing loss has been disputed. This study compares 44 insulin-dependent diabetics with 38 age and sex matched controls. All had pure tone and speech audiometry performed, with any diabetics showing sensorineural deafness undergoing stapedial reflecx decat tests. In 14 diabetics stapedial reflex tests showed no tone decay in any patient, but seven showed evidence of recruitment. Analysis of vaiance showed the diabetics to be significantly deafer than the control population.The hearing loss affected high frequencies in both sexes, but also low frequencies in the male. Speech discrimination scores showed no differences. Further analysis by sex showed the males to account for most of the differences. Analysys of the audiograms showered mostly a high tone loss. Finally duration of disbetes, insulin dosage and family history of diabtes were not found to have a significant effect on threshold.

Electrochemical Impedance Imaging on Conductive Surfaces

2021 ◽  
Author(s):  
Yaping Shi ◽  
Guangxia Feng ◽  
Xiaoliang Li ◽  
Xu Yang ◽  
Abdulsattar H. Ghanim ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Impedance Imaging ◽  
Conductive Surfaces

Use of Measured Mobility to Improve SEA Predictions in the Mid-Frequency Range

1999 ◽  
Author(s):  
Jerome E. Manning
Keyword(s):  
Dynamic Systems ◽  
Broad Band ◽  
Measured Data ◽  
Hybrid Technique ◽  
Complex Dynamic ◽  
Low Frequencies ◽  
Large Variability ◽  
High Frequencies ◽  
Complex Dynamic Systems ◽  
Light Coupling

Abstract Statistical energy analysis provides a technique to predict acoustic and vibration levels in complex dynamic systems. The technique is most useful for broad-band excitation at high frequencies where many modes contribute to the response in any given frequency band. At mid and low frequencies, the number of modes contributing to the response may be quite small. In this case SEA predictions show large variability from measured data and may not be useful for vibroacoustic design. This paper focuses on the use of measured data to improve the accuracy of the predictions. Past work to measure the SEA coupling and damping loss factors has not been successful for a broad range of systems that do not have light coupling. This paper introduces a new hybrid SEA technique that combines measured mobility functions with analytical SEA predictions. The accuracy of the hybrid technique is shown to be greatly improved at mid and low frequencies.

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