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Surface Resistance (surface + resistance)

Distribution by Scientific Domains

Engineering	42%
Chemistry	42%

Selected Abstracts

Surface Resistance and Potentiometric Response of Polymeric Membranes Doped with Nonionic Surfactants

ELECTROANALYSIS, Issue 19 2004
Liya Muslinkina
Abstract The influence of lipophilic, electrically neutral surfactants added to the membrane on the ion transfer resistance between an aqueous sample and a polymeric ion-selective membrane has been studied by electric impedance spectroscopy and potentiometry. An increase in the surface resistance and a shift of the apparently super-Nernstian response to lower sample ion activities has been observed when using the nonpolar bis(2-ethylhexyl) sebacate as plasticizer. [source]

Generating heat from conducting polypyrrole-coated PET fabrics

ADVANCES IN POLYMER TECHNOLOGY, Issue 3 2005
Akif Kaynak
Abstract Heating effects in polypyrrole-coated polyethyleneterephthalate (PET)-Lycra® fabrics were studied. Chemical synthesis was employed to coat the PET fabrics by polypyrrole using ferric chloride as oxidant and antraquinone- 2-sulfonic acid (AQSA) and naphthalene sulfonic acid (NSA) as dopants. The coated fabrics exhibited reasonable electrical stability, possessed high electrical conductivity, and were effective in heat generation. Surface resistance of polypyrrole-coated fabrics ranged from approximately 150 to 500 ,/square. Different connections between conductive fabrics and the power source were examined. When subjected to a constant voltage of 24 V, the current transmitted through the fabric decreased about 10% in 72 h. An increase in resistance of conductive fabrics subjected to constant voltage was observed. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24: 194,207, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20040 [source]

Surface Resistance and Potentiometric Response of Polymeric Membranes Doped with Nonionic Surfactants

Metal Ion Implantation for the Fabrication of Stretchable Electrodes on Elastomers

ADVANCED FUNCTIONAL MATERIALS, Issue 3 2009
Samuel Rosset
Abstract Here, the use of low-energy metal ion implantation by filtered cathodic vacuum arc to create highly deformable electrodes on polydimethylsiloxane (PDMS) membranes is reported. Implantation leads to the creation of nanometer-size clusters in the first 50,nm below the surface. When the elastomer is stretched, these small clusters can move relative to one another, maintaining electrical conduction at strains of up to 175%. Sheet resistance versus ion dose, resistance versus strain, time stability of the resistance, and the impact of implantation on the elastomer's Young's modulus are investigated for gold, palladium, and titanium implantations. Of the three tested metals, gold has the best performance, combining low and stable surface resistance, very high strain capabilities before loss of electrical conduction, and low impact on the Young's modulus of the PDMS membrane. These electrodes are cyclically strained to 30% for more than 105 cycles and remain conductive. In contrast, sputtered or evaporate metals films cease to conduct at strains of order 3%. Additionally, metal ion implantation allows for creating semi-transparent electrodes. The optical transmission through 25-µm-thick PDMS membranes decreases from 90% to 60% for Pd implantations at doses used to make stretchable electrodes. The implantation technique presented here allows the rapid production of reliable stretchable electrodes for a number of applications, including dielectric elastomer actuators and foldable or rollable electronics. [source]

Evapotranspiration rates and crop coefficients for a restored marsh in the Sacramento,San Joaquin Delta, California, USA,

HYDROLOGICAL PROCESSES, Issue 6 2008
Judy Z. Drexler
Abstract The surface renewal method was used to estimate evapotranspiration (ET) for a restored marsh on Twitchell Island in the Sacramento,San Joaquin Delta, California, USA. ET estimates for the marsh, together with reference ET measurements from a nearby climate station, were used to determine crop coefficients over a 3-year period during the growing season. The mean ET rate for the study period was 6 mm day,1, which is high compared with other marshes with similar vegetation. High ET rates at the marsh may be due to the windy, semi-arid Mediterranean climate of the region, and the permanently flooded nature of the marsh, which results in very low surface resistance of the vegetation. Crop coefficient (Kc) values for the marsh ranged from 0·73 to 1·18. The mean Kc value over the entire study period was 0·95. The daily Kc values for any given month varied from year to year, and the standard deviation of daily Kc values varied between months. Although several climate variables were undoubtedly responsible for this variation, our analysis revealed that wind direction and the temperature of standing water in the wetland were of particular importance in determining ET rates and Kc values. Published in 2007 by John Wiley & Sons, Ltd. [source]

A new approach to measuring the aerodynamic resistance to evaporation within a northern peatland using a modified Bellani plate atmometer

HYDROLOGICAL PROCESSES, Issue 19 2006
Nicholas Kettridge
Abstract This study considers evaporation from northern peatlands, which are important global stores of soil carbon. Evaporation is commonly simulated using the Penman,Monteith model. The model incorporates the aerodynamic resistance to vapour transfer (ra), which can currently only be measured using expensive, labour intensive micro-meteorological methods. A new approach to measuring ra is presented. The approach involves accurately measuring the evaporation from a modified Bellani plate atmometer, of known surface resistance and temperature. With knowledge of basic meteorological parameters, ra can then be calculated. The approach is compared to modelled resistances within a northern peatland: no significant difference was found between modelled and measured ra. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Modeling of conductor losses in capacitors with rectangular and circular plates

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2009
A. Deleniv
Abstract Analytic models are developed for the losses in the plates of MIM capacitors. The formulas are derived for the equivalent loss tangent and resistance of the arbitrary thick rectangular electrodes. An equivalent surface resistance is introduced for an arbitrary thick conductor. The accuracy of the model is demonstrated by comparison with rigorous Sonnet simulation and available alternative approach. The formula for the resistance of electrically thick circular electrodes is obtained. The derived expressions are verified via comparison with rigorous HFSS (high frequency structure simulator) simulations using eigenmode solver. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source]