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1

Estimating depth to argillic soil horizons using apparent electrical conductivity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maps of apparent electrical conductivity (ECa) of the soil profile are widely used in precision agriculture practice and research. A number of ECa sensors are commercially available, each with a unique response function (i.e., the relative contribution of soil at each depth to the integrated ECa rea...

2

MAPPING, MONITORING, AND ASSESSMENT OF SALINITY USING APPARENT SOIL ELECTRICAL CONDUCTIVITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Geo-referenced measurements of apparent soil electrical conductivity (ECa) provide a potential means of characterizing soil spatial variability. It is the objective to present the practical technology, methodology, and guidelines for measuring, monitoring, mapping, and assessing soil salinity (and ...

3

Estimating Depth to Argillic Soil Horizons using Apparent Electrical Conductivity Response Functions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maps of apparent electrical conductivity (ECa) of the soil profile are widely used in precision agriculture practice and research. A number of ECa sensors are commercially available, each with a unique response function (i.e., the relative contribution of soil at each depth to the integrated ECa rea...

4

Effect of Soil Water on Apparent Soil Electrical Conductivity and Texture Relationships in a Dryland Field.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Precision farming (PF) research has shown that when high salinity levels are not present, apparent soil electrical conductivity (ECa) is usually strongly correlated with soil texture. Mapping ECa has been promoted as a means for identifying management zones that are needed for variable application ...

5

APPARENT ELECTRICAL CONDUCTIVITY AS A TOOL FOR DELINEATING SPATIAL PATTERNS IN INHERENT SOIL PROPERTIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil properties affecting crop yield exhibit spatial variability. Apparent electrical conductivity (ECa) can be economically measured and is well correlated with many soil properties. Methods for processing ECa survey data and determining the relationship between ECa and soil properties are needed. ...

6

Relating apparent electrical conductivity to soil properties across the north-central USA  

Microsoft Academic Search

Apparent electrical conductivity (ECa) of the soil profile can be used as an indirect indicator of a number of soil physical and chemical properties. Commercially available ECa sensors can efficiently and inexpensively develop the spatially dense datasets desirable for describing within-field spatial soil variability in precision agriculture. The objective of this research was to relate ECa data to measured soil

K. A. Sudduth; N. R. Kitchen; W. J. Wiebold; W. D. Batchelor; G. A. Bollero; D. G. Bullock; D. E. Clay; H. L. Palm; F. J. Pierce; R. T. Schuler; K. D. Thelen

2005-01-01

7

Soil Properties Assessment using Apparent Electric Conductivity (ECa) in semi-arid Environments of Northern Tanzania  

NASA Astrophysics Data System (ADS)

Semi-arid environments such as in Northern Tanzania are characterized by a variety of degradation processes due to long dry periods and short but intensive rainfall events. High potential evaporation, high run-off rates, and low water holding capacities are typical for the present soils. The area is mainly covered by semi-arid savannah, the dominating crop is maize and extensive grazing is conducted. Soil properties and their spatial distribution play a critical role for hydrologic processes. To assess the spatial distribution of these soil properties we utilized a Electromagnetic Induction (EMI) device that induce an electromagnetic field into the soil, creating an electric current. The strength of a resulting secondary electromagnetic field is recorded as the apparent electric conductivity (ECa), measured in mS/m. ECa can provide an indirect indicator of important soil properties. Factors that influence ECa include soil salinity, clay content and cation exchange capacity (CEC), clay mineralogy, soil pore size and distribution, soil moisture content, and temperature. However, in non-saline soils, conductivity variations are primarily a function of soil texture, moisture content, and CEC. There are few studies, related to EMI measurements, conducted in semi-arid environments. In this study we conducted field measurements with the GSSI Profiler EMP-400. Soil physical characteristics were also measured in field on typical soil profiles to get the respective calibration data, validation was done by lab analysis. We analyzed the spatial pattern of the soil ECa maps to determine relationships with soil properties, with a focus on soil texture. The regionalization was carried out using stochastic models. In this study we tested classification and regression trees as well as advanced stochastic gradient boosting methods.

Märker, M.; Quénéhervé, G.

2012-04-01

8

Spatial interpolation of soil organic carbon using apparent electrical conductivity as secondary information  

NASA Astrophysics Data System (ADS)

Soil organic carbon (SOC) spatial characterization is necessary to evaluate under what circumstances soil acts as a source or sink of carbon dioxide. However, at the field or catchment scale it is hard to accurately characterize its spatial distribution since large numbers of soil samples are necessary. As an alternative, near-surface geophysical sensor-based information can improve the spatial estimation of soil properties at these scales. Electromagnetic induction (EMI) sensors provide non-invasive and non-destructive measurements of the soil apparent electrical conductivity (ECa), which depends under non-saline conditions on clay content, water content or SOC, among other properties that determine the electromagnetic behavior of the soil. This study deals with the possible use of ECa-derived maps to improve SOC spatial estimation by Simple Kriging with varying local means (SKlm). Field work was carried out in a vertisol in SW Spain. The field is part of a long-term tillage experiment set up in 1982 with three replicates of conventional tillage (CT) and Direct Drilling (DD) plots with unitary dimensions of 15x65m. Shallow and deep (up to 0.8m depth) apparent electrical conductivity (ECas and ECad, respectively) was measured using the EM38-DD EMI sensor. Soil samples were taken from the upper horizont and analyzed for their SOC content. Correlation coefficients of ECas and ECad with SOC were low (0.331 and 0.175) due to the small range of SOC values and possibly also to the different support of the ECa and SOC data. Especially the ECas values were higher in the DD plots. The normalized ECa difference (?ECa), calculated as the difference between the normalized ECas and ECad values, distinguished clearly the CT and DD plots, with the DD plots showing positive ?ECa values and CT plots ?ECa negative values. The field was stratified using fuzzy k-means (FKM) classification of ?ECa (FKM1), and ECas and ECad (FKM2). The FKM1 map mainly showed the difference between CT and DD plots, while the FKM2 map showed both differences between CT and DD and topography-associated features. Using the FKM1 and FKM2 maps as secondary information accounted for 30% of the total SOC variability, whereas plot and management average SOC explained 44 and 41%, respectively. Cross validation of SKlm using FKM2 reduced the RMSE by 8% and increased the efficiency index almost 70% as compared to Ordinary Kriging. This work shows how ECa can improve the spatial characterization of SOC, despite its low correlation and the small size of the plots used in this study.

Martinez, G.; Vanderlinden, K.; Ordóñez, R.; Muriel, J. L.

2009-04-01

9

Apparent Electrical Conductivity of Porous Titanium Prepared by the Powder Metallurgy Method  

NASA Astrophysics Data System (ADS)

Porous titanium is produced by the powder metallurgy method. Dependence of the electrical conductivity on the porosity and pore size is investigated and the experimental results are compared with a number of models. It is found that the minimum solid area model could be successfully applied to describe the relationship between the electrical conductivity and the porosity of porous titanium. This kind of conductivity increases with increasing pore sizes.

Li, Cheng-Feng; Zhu, Zhen-Gang

2005-10-01

10

Characterizing the spatial variability of soil infiltration using apparent electrical conductivity  

NASA Astrophysics Data System (ADS)

Implementation of irrigation systems and models of water flow and solute transport, requires continuous and accurate hydrological information. Apparent electrical conductivity (ECa) has been used to characterize the spatial behavior of soil properties. The objective was to characterize the spatial variability of soil infiltration at farm scale using ECa measurements. ECa measurements of a 42 ha farm were collected for the top 0-30cm (ECa(s)) and 0-90cm (ECa(d)) soil using the Veris® 3100. ECa maps were generated for both depths, using geostatistical interpolation techniques. From these maps, three general areas were delineated, named High, Medium, and Low ECa zones. At each zone, three sub samples were collected. Infiltration, altimetry (Alt) and effective depth (ED) were measured. Soil samples were taken at two depths 0-30 (Sh) and 30-60 (Dp). Bulk density (?b), clay content and organic matter (OM) were analyzed. Infiltration rate (i) was estimated using a disc infiltrometer. Soil series were Petrocalcic Paleudoll and Typic Argiudoll. Spatial variability of soil properties were analyzed by descriptive statistics. High ECa zones showed greater Alt and lesser ED. Likewise, Sh and Dp soil samples had greater ?b and clay content, and lesser OM content. Medium and Low ECa zones were situated at similar areas of Alt and ED. Likewise, ?b and OM content showed similar values at the two studied depths. In the Medium ECa zone, clay content was higher in Sh sampler. In general, the lowest i was in the High ECa zone, while in Medium and Low ECa zones, i values were similar. ECa was associated with clay content and OM, therefore with ?b and i. It is concluded that spatial variability of soil infiltration could be characterized through ECa.

Castro Franco, Mauricio; Domenech, Marisa; Aparicio, Virginia; Costa, José Luis

2013-04-01

11

CHARACTERIZATION OF APPARENT SOIL ELECTRICAL CONDUCTIVITY VARIABILITY IN IRRIGATED SANDY AND NON-SALINE FIELDS IN COLORADO  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent advances in apparent soil electrical conductivity (ECa) sensor technology have provided the opportunity to rapidly map the nature of soil spatial variability for site-specific management. Characterizing (or identifying the causes of) the ECa variability, however, has remained difficult with ...

12

Modeling Baseflow from an Alluvial Aquifer Using Hydraulic-Conductivity Data Obtained from a Derived Relation with Apparent Electrical Resistivity  

NASA Astrophysics Data System (ADS)

In order to accurately quantify the water flux entering the Netherlands from Belgium via the Meuse River and its alluvial plain, the Belgian Ministry of Public Works has supported hydrological and hydrogeological studies in the area between the city of Liège (Belgium) and the Dutch border. The groundwater fluxes from the Albert Canal to the Meuse River and those passing around the weir-lock systems within the alluvial gravel deposits are not measured by the existing surface-water gauging system; therefore, detailed quantitative hydrogeological studies of the groundwater fluxes in these alluvial deposits were needed. A detailed three-dimensional finite-element numerical model was used to compute these fluxes. Previous hydrogeological studies involving piezometers, pumped wells, and electrical soundings provided, respectively, data for potentiometric maps, local values of hydraulic condictivity, and more than 200 measurements of the apparent geoelectrical resistivity of the gravel deposits. From this data set, a new correlation between geoelectrical resistivity and hydraulic conductivity was used to define a spatially distributed set of hydraulic-conductivity values to be entered in the model. Maps and measured potentiometric heads were used as references for the calibration of the model, and features of the model, such as layer geometry, external sink and source terms, and boundary conditions, were selected on the basis of all available information. Four non-horizontal layers were discretized as 2,356 elements. On the basis of the model, the additional flow crossing to the Netherlands via the alluvial aquifer and the Meuse River is about 5.4 3/s during the summer.

Dassargues, A.

1997-03-01

13

Spatial variability of soil apparent electrical conductivity(ECa) and the water table depth in an alluvial valley under different uses.  

NASA Astrophysics Data System (ADS)

The apparent soil electrical conductivity (ECa), measured by contact or by electromagnetic induction (EMI), has been widely used as a variable that is correlated with physical and chemical soil properties. Therefore this property is used as a parameter in precision agriculture, to enable assessment of soil spatial variability and defining management units, allowing obtaining information about other soil properties like texture, salinity, water content, among others. These conditions are adequate to study spatial variability of data with the help of geostatistics, which models the spatial variability of soil properties, allowing the construction of spatial variability maps unbiased and with minimum variance. Thus, the goal this work was assess the variability special of electrical conductivity apparent soil (ECa) and the water table level in an alluvial valley in the brazilian semi-arid adopting different uses. The studied alluvial valley is located in Pesqueira (Pernambuco State, Brazil) and has 421.0 hectares. The main soil types occurring in the valley are: Fluvic Neosols , litholic Neossols and regolithic Neosols . Climate according to Koppen's classification is BSsh type, with total annual rainfall average of 730mm. The attributes evaluated in this study were sampled at 88 piezometric wells. The apparent soil electrical conductivity (ECa) was measured by electromagnetic induction with the EM38 device (Geonics Ltd) in vertical dipole (effective depth 1.5m). The ground water table was determined in piezometric wells with the aid of a measuring tape. Data were analyzed by using descriptive statistics and geostatistical tools. The land use map was constructed using field verification and spatialized by means of GIS. The attributes analyzed showed Normal frequency distribution. ECa readings ranged between 8 and 79 mS m-1. The major differences between the ECa values are due to the variation of water content in soil and distance from the water table at the soil surface. The water table in the study area ranged from 0.8 to 3.8 m deep. The Pearson linear correlation found for the data in the study was zero (r = -0.0185). The Gaussian model was the best fit to the data, and the water table had the highest range value (a = 500.00 m). The maps of spatial variability of water table and ECa have similar spatial behavior, indicating that where the water table is deeper at places with the lowest ECa.

Siqueira, G. M.; Fontes Júnior, R. V. P.; Montenegro, A. A. A.; Barros, Y. L.; Silva, E. F. F.

2012-04-01

14

Effectiveness of apparent electrical conductivity surveys at varying soil water contents for assessing soil and water dynamics across a rainfed mountain olive orchard in SW Spain.  

NASA Astrophysics Data System (ADS)

Knowledge and understanding of the spatio-temporal variability of soil physical and chemical properties at the field or micro-catchment scale are of prime importance for many agricultural and environmental applications that aim at soil, water and carbon conservation. Geophysical methods, such as electromagnetic induction (EMI), are nowadays a key tool to monitor these properties across relevant scales, as a result of their non-destructive nature and their capability to survey repeatedly large areas within a small time window. Geophysical instrument response depends on the electromagnetic properties of the subsoil and for EMI in particular moist soil conditions are generally considered as most suitable for data acquisition. In water-limited environments, such as those under Mediterranean climate, these conditions are not met during large periods of the year, apparently hampering the usefulness of the method in these regions. The aim of this study is to obtain a better understanding of the sensor response and the contribution of soil properties to the geophysical signals under varying water contents. An experimental micro-catchment in SW Spain under rainfed olive cultivation was surveyed for apparent electrical conductivity (ECa) on 11 moments in time using a Dualem-21S. In addition, ECa and soil water content (SWC) was measured at 48 locations throughout the catchment on each survey date. At each of these locations, soil profile samples were analyzed for texture, soil organic matter content (SOM), soil depth, gravel content, and bulk density. Overall, correlations between the different soil properties and ECa improved with increasing SWC, although the ECa patterns remained constant in time. Time-lapse imaging offers the most promising results under the conditions of this study, but still requires at least one survey under wet soil conditions. Despite the smaller correlations between ECa and soil properties under dry conditions, ECa patterns are still relevant for assessing soil and water dynamics at the field or micro-catchment scale.

Aura, Pedrera,; De Vijver, Ellen, Van; Karl, Vanderlinden,; Sergio, Martos-Rosillo; Meirvenne, Marc, Van; Espejo-Pérez, Antonio, J.; Encarnación V., Taguas,; Giráldez, Juan, V.

2013-04-01

15

Electrically conductive diamond electrodes  

DOEpatents

An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

Swain, Greg (East Lansing, MI); Fischer, Anne (Arlington, VA),; Bennett, Jason (Lansing, MI); Lowe, Michael (Holt, MI)

2009-05-19

16

Polymers that Conduct Electricity.  

ERIC Educational Resources Information Center

|Although polymers are regarded as electrical insulators, it was discovered that they can be made to conduct electricity. This discovery has opened vast new practical and theoretical areas for exploration by physicists and chemists. Research studies with these conducting polymers and charge-transfer salts as well as possible applications are…

Edelson, Edward

1983-01-01

17

Electrically conductive composite material  

DOEpatents

An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistant pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like.

Clough, Roger L. (Albuquerque, NM); Sylwester, Alan P. (Albuquerque, NM)

1989-01-01

18

Electrical Conduction Activity  

NSDL National Science Digital Library

This resource provides an introductory activity on electrical conduction. As the module states, "electrical conduction, the movement of electrical charges, is a mechanism for passing energy and signals from one place to another." The activity covers concepts such as insulators, conductors, semiconductors, superconductors, and ballistic conduction at nanoscale. This module allows students to test their knowledge as they go.The other educational modules in this series can be found here. Instructors and students are encouraged to sign up with the Electron Technologies site here before starting to use these materials.

2012-10-02

19

Electrically conductive material  

DOEpatents

An electrically conductive material for use in solid oxide fuel cells, electrochemical sensors for combustion exhaust, and various other applications possesses increased fracture toughness over available materials, while affording the same electrical conductivity. One embodiment of the sintered electrically conductive material consists essentially of cubic ZrO.sub.2 as a matrix and 6-19 wt. % monoclinic ZrO.sub.2 formed from particles having an average size equal to or greater than about 0.23 microns. Another embodiment of the electrically conductive material consists essentially at cubic ZrO.sub.2 as a matrix and 10-30 wt. % partially stabilized zirconia (PSZ) formed from particles having an average size of approximately 3 microns.

Singh, Jitendra P. (Bollingbrook, IL); Bosak, Andrea L. (Burnam, IL); McPheeters, Charles C. (Woodridge, IL); Dees, Dennis W. (Woodridge, IL)

1993-01-01

20

Electrically conductive material  

DOEpatents

An electrically conductive material is described for use in solid oxide fuel cells, electrochemical sensors for combustion exhaust, and various other applications possesses increased fracture toughness over available materials, while affording the same electrical conductivity. One embodiment of the sintered electrically conductive material consists essentially of cubic ZrO[sub 2] as a matrix and 6-19 wt. % monoclinic ZrO[sub 2] formed from particles having an average size equal to or greater than about 0.23 microns. Another embodiment of the electrically conductive material consists essentially at cubic ZrO[sub 2] as a matrix and 10-30 wt. % partially stabilized zirconia (PSZ) formed from particles having an average size of approximately 3 microns. 8 figures.

Singh, J.P.; Bosak, A.L.; McPheeters, C.C.; Dees, D.W.

1993-09-07

21

Relationship between apparent soil electrical conductivity (ECa) and soil attributes at an experimental parcel under pasture in a region of Galicia, Spain.  

NASA Astrophysics Data System (ADS)

Spatial characterization of the variability of soil properties is a central point in site-specific agricultural management and precision agriculture. Geospatial measures of geophysical attributes are useful not only to rapidly characterize the spatial variability of soil properties but also for soil sampling optimization. This work reports partial results obtained at an experimental parcel under pasture located at Castro de Ribeira do Lea (Lugo/ Galicia/ Spain). An ECa automated survey was conducted in September 2011 employing an EM-38 DD (Geonics Ltd.) installed in a nonmetallic car, according to parallel lines spaced 10m one from each other and oriented at the east-west direction. The ECa values were recorded every second with a field computer and the locations were geo-referenced using a GPS. The entire survey was carried out in 1hour and 45 minutes and corrections due to differences in temperature were made. A total of 9.581 ECa registers were retained, configuring a sampling intensity of approximately 1 register per 1.5 m2. Employing the software ESAP 2.35 and the computational tool ESAP-RSSD, eighty positions were selected at the field to extract disturbed and undisturbed soil samples at two depths: 0.0-0.2m, 0.2-0.4m. Ten physical attributes (clay, silt, total sand, coarse sand and fine sand contents, soil bulk density, particle density, total porosity, soil water content, percentage of gravels) and 17 chemical attributes (soil organic matter-SOM, pH, P, K, Ca, Mg, Al, H+Al, Sum of bases-S, Cation exchange capacity-CEC, Base saturation-V%, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were determined. The relationship between the geophysical variables and the soil attributes was performed using statistical and spatial analysis. There were significant correlations (p<0.01) between the geophysical variables and the textural attributes clay, silt, total sand and coarse sand contents. The biggest correlation (0.5623) was between ECa-V (vertical component) and clay content. Also, significant correlations (p<0.05) were found between the ECa-V and soil bulk density, total porosity, percentage of gravels and soil water content. Considering the chemical attributes, significant correlations (p< 0.01) were found between ECa-V and SOM and Cd, and between ECa-H (horizontal component) and SOM and Fe. Other significant correlations (p<0.05) were found between ECa-V and 6 soil chemical attributes: P, Ca, S, Fe, Ni and Pb. The biggest correlation was between ECa-V and SOM (-0.5942). In resume, clay content, SOM, Cd and Fe are the soil attributes better correlated with the observed variation of the ECa at the field. Additional analysis should be performed to compare the spatial patterns of these soil attributes and the ECa as a tool to proper define management zones in the area. Acknowledgements: This work was funded in part by Spanish Ministry of Science and Innovation (MICINN) in the frame of project CGL2009-13700-C02. Financial support from CAPES/GOV., Brazil, is also acknowledged by Prof. M. de A. Marinho.

Marinho, Mara de A.; Dafonte, Jorge D.; Armesto, Montserrat V.; Paz-González, Antonio; Raposo, Juan R.

2013-04-01

22

Electrical conductive composite lubricants  

SciTech Connect

In power and electronic systems, electrical contact resistance is a major issue. For mechanical connections and sliding contacts, power losses and electrical noise are critical concerns. These issues are of particular interest to all industrial members of the Auburn CCDS. Research has been conducted to develop a variety of contact materials, both for solid lubricant films and composite paper lubricants. A combination of low electrical resistance, good lubricating properties, long wear-life, and low sliding electrical noise was achieved using a metal-cellulose composite paper with dichalcogenide powders entrapped in the porous paper matrix. Advancements in developing these conductive lubricants can increase contact lifetime and reliability in many space and terrestrial applications. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

Tatarchuk, B.J.; Wehrman, K.A.; Yang Zhang; Teh-Shing Lee; Krishnagopalan, G.A. [Department of Chemical Engineering, Auburn University, Alabama 36849-5127 (United States)

1995-01-25

23

Wildfire plume electrical conductivity  

NASA Astrophysics Data System (ADS)

Wildfires are weakly ionized gas. The ionization is mainly due to plant's inorganic ash content species (more especially potassium), that are emitted from thermally decomposing plant structure into the flame during combustion. The amount of ionization in flames with potassium impurities is influenced by both the temperature and the amount potassium impurities in the flame. A numerical experiment was conducted using a local thermal equilibrium-based model to study the influence of inorganic wildfire contents on wildfire electrical conductivity. Simulated very high intensity wildfires (21-90 MWm-1) were used to quantify steady-state electrical conductivity. Its variation with wildfire plume height is important for high voltage power flashover research. In the simulation, vegetation potassium content was varied from 0.50% to 3.0% on dry weight basis, a reflection of its content in natural vegetation. The model predicted a maximum conductivity of 0.053 mhom-1 in 90 MWm-1 crown fire in vegetation with 3.0% potassium content. A 90 MWm-1 crown fire in vegetation with potassium content of 0.5% was predicted to produce a maximum conductivity of 0.022 mhom-1. Electrical conductivities were lower for a shrub fire with an intensity of 21 MWm-1. The model predicted conductivities of 0.0021 and 0.0009 mhom-1 for potassium content of 3.0 and 0.5% in vegetation, respectively.

Mphale, Kgakgamatso; Heron, Malcom

2007-09-01

24

Electrical Conduction Assessment  

NSDL National Science Digital Library

This brief assessment on Electrical Conduction is intended to be used after students have completed the introductory activity on the topic, which may be located here. The assessment consists of 8 multiple choice and short answer questions. The other educational modules in this series can be found here. Instructors and students are encouraged to sign up with the Electron Technologies site here before starting to use these materials.

2012-10-02

25

Electrically conductive ceramic powders  

NASA Astrophysics Data System (ADS)

Electrically conductive ceramic powders were investigated in this project. There are three ways to produce those materials. The first is doping alkali metal into the titanium dioxides in an inert or reducing atmosphere. The second is reducing un-doped titanium dioxide, forming a non-stoichiometric composition in a hydrogen atmosphere. The third is to coat a conductive layer, reduced titanium dioxide, on an insulating core such as alumina. Highly conductive powders have been produced by all these processes. The conductivity of powder compacts ranged between 10-2 and 10° S/cm. A novel doping process was developed. All samples were doped by a solid-vapor reaction instead of a solid state reaction. Titanium dioxide was doped with alkali metals such as Na or Li in this study. The alkali metal atom contributes an electron to the host material (TiO2), which then creates Ti 3+ ion. The conductivity was enhanced by creating the donor level due to the presence of these Ti3+ ions. The conductivity of those alkali doped titanium oxides was dependent on the doping level and charge mobility. Non-stoichiometric titanium oxides were produced by reduction of titanium dioxide in a hydrogen atmosphere at 800°C to 1000°C for 2 to 6 hours. The reduced titanium oxides showed better stability with respect to conductivity at ambient condition when compared with the Na or Li doped samples. Conductive coatings were prepared by coating titanium precursors on insulating core materials like SiO2, Al2O3 or mica. The titania coating was made by hydrolysis of titanyl sulfate (TiOSO 4) followed by a reduction procedure to form reduced titanium oxide. The reduced titanium oxides are highly conductive. A uniform coating of titanium oxides on alumina cores was successfully produced. The conductivity of coated powder composites was a function of coating quantity and hydrolysis reaction temperature. The conductivity of the powder as a function of structure, composition, temperature, frequency and moisture was studied. Three classifications of structure were identified for alkali-doped titanium oxides: (1) Pure titanium dioxide phase with alkali ions located in interstitial positions. (2) The titanium bronze phases. (3) Alkali-doped titanium oxides. Highly conductive powders were obtained in the first and second classifications with conductivity of 10-2 to 10° S/cm. Materials in the third classification had poor conductivity below 10-3 S/cm. The conductivity of a powder was determined mainly by the grain conductivity and the grain contact conductivity. The present results of impedance spectroscopy suggested that the grain contact resistance was a major factor of the electrical resistance of the samples. The aging effect at different moisture conditions was also caused by an increase of the contact resistance. Both sodium-doped and reduced titanium oxides showed re-oxidation at elevated temperature (above 140°C) in air, which is most probably caused by oxidizing the Ti3+ ions under those conditions. Lithium doped titanium oxides did not show this re-oxidation at temperatures up to 200°C. Theoretical models were applied to describe the effects of porosity, contact configuration and grain surface on conductivity of powder compacts. Percolation theory was used in the present study to demonstrate the effect of mixtures of conductive and non-conductive powders, which is one of applications for conductive ceramic powders when they are used as filler materials in paper, paints or plastics.

Lu, Yanxia

1999-11-01

26

Measurement of Apparent Thermal Conductivity by the Thermal Probe Method  

Microsoft Academic Search

ABSTRACT: Three thermal,probes were,constructed,in accor- dance with ASTM D 5334 and calibrated using heat-flow metre data. The temperature-time response,of the thermal probes for de- termining apparent thermal conductivity Aunder transient state con- ditions was logged at 1 s intervals. The instrumentation,used re- duced,the determinate,error associated with voltage and current measurements,to a negligibly small value that made,the uncertainty in,A dependent,on the

RE Link; K Manohar; DW Yarbrough; JR Booth

2000-01-01

27

Estimation of volumetric myocardial apparent conductivity from endocardial electro-anatomical mapping.  

PubMed

Estimating patient-specific electrical tissue parameters is of considerable benefit towards personalization of cardiac biophysical models. In this paper, an adaptive inverse parameter estimation algorithm is proposed to estimate the myocardial apparent conductivity from endocardial electrical potential measurements. The forward electrophysiology problem is posed as an Eikonal model and is solved using an anisotropic fast marching method. The conductivity estimation algorithm is validated on patient data obtained using hybrid X-ray/magnetic resonance imaging. Future directions towards improving such estimation procedures are also indicated. PMID:19964788

Chinchapatnam, Phani; Rhode, Kawal S; Ginks, Matthew; Mansi, Tommaso; Peyrat, Jean-Marc; Lambiase, Pier; Rinaldi, C; Razavi, Reza; Arridge, Simon; Sermesant, Maxime

2009-01-01

28

Electrically conducting carbon fiber sorbents  

Microsoft Academic Search

A new class of carbon fiber materials has been developed: electrically conducting fiber sorbents. Studies have been made on\\u000a the effects from ACFM production parameters on the porosity, pore structure, bulk resistivity, and electrical capacity. This\\u000a enables one to forecast the properties of electrically conducting ACFM over wide ranges and to make sorbents with given sorption\\u000a and electrophysical characteristics.

A. A. Lysenko; O. V. Astashkina; V. A. Lysenko; L. E. Vinogradova

2008-01-01

29

Electrical conductivity of compressed argon  

SciTech Connect

The authors report calculations of the electrical conductivity of solid argon as a function of compression within the density functional local density approximation formulation for a norm-conserving pseudopotential using both electron-phonon coupling and molecular dynamics techniques.

Bauer, R. [Univ. Regensburg (Germany); Windl, W.; Collins, L.; Kress, J.; Kwon, I. [Los Alamos National Lab., NM (United States)

1997-10-01

30

Influence of surface conductivity on the apparent zeta potential of amorphous silica nanoparticles.  

PubMed

Zeta potential is a physicochemical parameter of particular importance in describing ion adsorption and double layer interactions between charged particles. However, for metal-oxide nanoparticles, the conversion of electrophoretic mobility measurements into zeta potentials is difficult. This is due to their very high surface electrical conductivity, which is inversely proportional to the size of the particle. When surface conductivity is similar to or higher than the electrical conductivity of bulk water, it can significantly lower the electrophoretic mobility of the particles. It follows that the magnitude of the apparent zeta potential determined from the Smoluchowski equation (disregarding surface conductivity) can be grossly underestimated. We use a basic Stern model to describe the electrochemical properties and to calculate the true zeta potential of amorphous silica nanoparticles immersed in NaCl solution. The parameters of our surface complexation model are adjusted by potentiometric titration and electrophoretic mobility measurements at high salinity (10(-1)M NaCl). Electrophoretic mobilities are calculated using Henry's electrokinetic transport model with specific surface conductivities and zeta potentials estimated by our surface complexation model. The very good agreement of calculated and measured electrophoretic mobilities confirms that the true zeta potential corresponds to the electrical potential at the outer Helmholtz plane (OHP). Consequently, the shear plane might be located close to the OHP. The assumption of the presence of a stagnant diffuse layer at the amorphous silica/water interface is therefore not required. PMID:24011560

Leroy, Philippe; Devau, Nicolas; Revil, André; Bizi, Mohamed

2013-08-16

31

Electrical Conductivity of Cryolite Melts  

NASA Astrophysics Data System (ADS)

This paper proposes an equation for the electrical conductivity of multicomponent cryolite-based mixtures. The equation is based on a physical model which assumes that the conductivity is proportional to the number density of the effective electric charges in the melt. The various authors in the available literature show a great discrepancy in conductivity data of cryolite-based melts. The equation based on the physical model enables determination of which set of data is preferable. Special consideration in this respect is given to the influence of magnesium flouride and lithium flouride additions to the melt.

Fellner, P.; Grjotheim, K.; Kvande, H.

1985-11-01

32

Electrically conductive polymer concrete coatings  

DOEpatents

A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

Fontana, Jack J. (Shirley, NY); Elling, David (Centereach, NY); Reams, Walter (Shirley, NY)

1990-01-01

33

Electrically conductive polymer concrete coatings  

DOEpatents

A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

Fontana, J.J.; Elling, D.; Reams, W.

1990-03-13

34

Electrically conductive polymer concrete coatings  

DOEpatents

A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin with 3.5 wt% modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag. 4 tabs.

Fontana, J.J.; Elling, D.; Reams, W.

1988-05-26

35

Electrically conductive polymer concrete coatings  

SciTech Connect

The corrosion of reinforcing steel embedded in concrete causes cracks and delamination in the concrete. The application of impressed current cathodic protection utilizing electrically conductive polymer concrete to distribute the current across concrete bridge deck surfaces is gradually becoming a standard practice in the highway industry. In order to protect the bridge substructures, a sprayable electrically conductive polymer concrete coating is being developed. This thin coating has a very low resistivity and can distribute the cathodic protection current across the concrete surfaces that are to be protected.

Fontana, J.J.

1985-10-01

36

Electrically conductive polymer concrete overlays  

NASA Astrophysics Data System (ADS)

The use of cathodic protection to prevent the corrosion of reinforcing steel in concrete structures has been well established. Application of a durable, skid-resistant electrically conductive polymer concrete overlay would advance the use of cathodic protection for the highway industry. Laboratory studies indicate that electrically conductive polymer concrete overlays using conductive fillers, such as calcined coke breeze, in conjunction with polyester or vinyl ester resins have resistivities of 1 to 10 ohm-cm. Both multiple-layer and premixed mortar-type overlays were made. Shear bond strengths of the conductive overlays to concrete substrates vary from 600 to 1300 psi, with the premixed overlays having bond strengths 50 to 100% higher than the multiple-layer overlays.

Fontana, J. J.; Webster, R. P.

1984-08-01

37

Electrically conductive polymer concrete overlays  

SciTech Connect

The use of cathodic protection to prevent the corrosion of reinforcing steel in concrete structures has been well established. Application of a durable, skid-resistant electrically conductive polymer concrete overlay would advance the use of cathodic protection for the highway industry. Laboratory studies indicate that electrically conductive polymer concrete overlays using conductive fillers, such as calcined coke breeze, in conjunction with polyester or vinyl ester resins have resistivities of 1 to 10 ohm-cm. Both multiple-layer and premixed mortar-type overlays have been made. Shear bond strengths of the conductive overlays to concrete substrates vary from 600 to 1300 psi, with the premixed overlays having bond strengths 50 to 100% higher than the multiple-layer overlays.

Fontana, J.J.; Webster, R.P.

1984-08-01

38

Electrically conductive rigid polyurethane foam  

DOEpatents

A rigid, moldable polyurethane foam comprises about 2 to 10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

Neet, T.E.; Spieker, D.A.

1983-12-08

39

Dynamics of electrically conducting fluids  

NASA Astrophysics Data System (ADS)

Electrically conducting fluids are described by the magneto-hydrodynamic (MHD) formalism that combines the classical laws of fluid mechanics and electromagnetism. After a brief review of this formalism, several examples of electrically conducting fluids will be discussed. For instance, liquid metal flows are important in several industrial applications including the steel industry as well as in the description of geophysical flows and laboratory experiments on the dynamo effect. Also, plasmas represent an important class of electrically conductive fluids when they are treated in the limit of continuous media. Plasma physics is relevant in the study of various astrophysical systems as well as in laboratory experiments on magnetic confinement fusion. The importance of MHD effects for the ITER (International Thermonuclear Experimental Reactor) experiment will also be briefly discussed. Numerical simulations of the MHD equations play an increasingly important role in the description of electrically conducting fluids. Recent numerical results will be presented and MHD turbulence will be analyzed in terms of energy transfers, locality functions as well as sub-grid scale modeling in large eddy simulations.

Carati, Daniele

2010-11-01

40

Conduction of Electricity in Gases  

Microsoft Academic Search

The conduction of electricity through gases has played ubiquitous roles in science and technology. It was responsible for many of the fundamental discoveries in atomic and molecular physics; gas discharge lighting is essential to every night operations; gas discharge lasers are still important in research and manufacturing; and all of advanced microelectronics depends on plasma enhanced processing. To a large

Alan Garscadden

2006-01-01

41

Influence of surface conductivity on the apparent zeta potential of TiO2 nanoparticles.  

PubMed

Zeta potential is a physico-chemical parameter of particular importance in describing ion adsorption and electrostatic interactions between charged particles. Nevertheless, this fundamental parameter is ill-constrained, because its experimental interpretation is complex, particularly for very small and charged TiO(2) nanoparticles. The excess of electrical charge at the interface is responsible for surface conductance, which can significantly lower the electrophoretic measurements, and hence the apparent zeta potential. Consequently, the intrinsic zeta potential can have a larger amplitude, even in the case of simple 1:1 electrolytes like NaCl and KCl. Surface conductance of TiO(2) nanoparticles immersed in a NaCl solution is estimated using a surface complexation model, and this parameter and particle size are incorporated into Henry's model in order to determine a constrained value of the zeta potential from electrophoresis. Interior conductivity of the agglomerates is calculated using a differential self-consistent model. The amplitude of estimated zeta potential is greater than that derived from the von Smoluchowski equation and corresponds to the electric potential at the outer Helmholtz plane calculated by our surface complexation model. Consequently, the shear plane may be located close to the OHP, contradicting the assumption of the presence of a stagnant diffuse layer at the TiO(2)/water interface. PMID:21316693

Leroy, Philippe; Tournassat, Christophe; Bizi, Mohamed

2011-01-11

42

The Electrical Conductivity of Molybdenite  

Microsoft Academic Search

Electrical conductivity of molybdenite (MoS2) as a function of voltage and temperature.-Measurements of the currents through narrow flat strips cut perpendicular to the crystallographic c-axis gave results for the range from 0° to about 200° C, in agreement with the equation: i=KVbe-kT, where, for the mineral in the ordinary state, k is about 3,000 and b generally about 1.6. When

A. T. Waterman

1923-01-01

43

The instantaneous apparent resistivity tensor: a visualization scheme for LOTEM electric field measurements  

NASA Astrophysics Data System (ADS)

Long-offset transient electromagnetic (LOTEM) data have traditionally been represented as early- and late-time apparent resistivities. Time-varying electric field data recorded in a LOTEM survey made with multiple sources can be represented by an `instantaneous apparent resistivity tensor'. Three independent, coordinate-invariant, time-varying apparent resistivities can be derived from this tensor. For dipolar sources, the invariants are also independent of source orientation. In a uniform-resistivity half-space, the invariant given by the square root of the tensor determinant remains almost constant with time, deviating from the half-space resistivity by a maximum of 6 per cent. For a layered half-space, a distance-time pseudo-section of the determinant apparent resistivity produces an image of the layering beneath the measurement profile. As time increases, the instantaneous apparent resistivity tensor approaches the direct current apparent resistivity tensor. An approximate time-to-depth conversion can be achieved by integrating the diffusion depth formula with time, using the determinant apparent resistivity at each instant to represent the resistivity of the conductive medium. Localized near-surface inhomogeneities produce shifts in the time-domain apparent resistivity sounding curves that preserve the gradient, analogous to static shifts seen in magnetotelluric soundings. Instantaneous apparent resistivity tensors calculated for 3-D resistivity models suggest that profiles of LOTEM measurements across a simple 3-D structure can be used to create an image that reproduces the main features of the subsurface resistivity. Where measurements are distributed over an area, maps of the tensor invariants can be made into a sequence of images, which provides a way of `time slicing' down through the target structure.

Caldwell, T. Grant; Bibby, Hugh M.

1998-12-01

44

The apparent power of electric circuits with switching elements in single-phase systems  

Microsoft Academic Search

This paper presents calculation of the apparent power of electric circuits with switching elements and various loads in single-phase systems. Attention is paid to the difference between such fundamental concepts as ldquothe electromotive force (EMF) of a voltage sourcerdquo and ldquothe input voltage of an electric circuitrdquo causing the electric current to flow. On that ground, an analysis of apparent

Oleksandr Osnach

2009-01-01

45

Electrical Conductivity of Tin Chalcogenide Melts.  

National Technical Information Service (NTIS)

It was demonstrated that in the molten tin sulphide, polarisation phenomena characteristic of ionic melts were lacking, while the electrical conductivity polytherms had a positive temperature coefficient. A drop of electrical conductivity at the crystalli...

V. V. Malinovskij A. A. Velikanov P. P. Sevcuk

1974-01-01

46

Study on Electrical Conductivity of Coal.  

National Technical Information Service (NTIS)

One of the engineering techniques in underground coal gasification is the electrical linking of holes drilled into the coal seam. The magnitude of electrical conductivity is one of the factors that will determine whether electrical linking is appropriate....

H. Ohuchi J. Soma T. Isobe

1968-01-01

47

Characterization of electrically conducting oxides  

SciTech Connect

This report discusses some of the highlights and publications of this years work. Listed below are the areas of interest and progress within the program: The studies of the Ba{sub 2}YCu{sub 3}O{sub 7-x} system have shown that the conduction processes (metallic or small polaron) have little temperature dependence and are almost entirely a function of oxygen stoichiometry. The substitution of 10 to 20 m% Ca and Co into LaCrO{sub 3} has enabled the system to be sintered to >95% TD at 1400{degree}C without deterioration of either the electrical conductivity or high temperature stability of the resulting dense ceramics. An elucidation of the structure of the high temperature (1400{degree}C) phases of La substitute SrTiO{sub 3} has demonstrated our abilities to determine small changes in structure as well as to determine cation defect concentrations using x-ray powder diffraction methods. In this study we were able to show that the oxidized state of Sr{sub 1-x}La{sub x}TiO{sub 3} contained cation vacancies. The studies in the Y{sub 1-x}Ca{sub x}CrO{sub 3} system also are yielding some important results. They are showing that this oxide system is more stable toward reduction than LaCrO{sub 3}. The construction of dual high temperature controlled atmosphere dilatometer has been completed. An effective-medium theory of hopping transport in binary systems is explaining the conductivity changes that occur when Mn is substituted into LaCrO{sub 3}.

Anderson, H.U.; Sparlin, D.M.

1989-01-01

48

INCREASING INFORMATION WITH MULTIPLE SOIL ELECTRICAL CONDUCTIVITY DATASETS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maps of apparent electrical conductivity (ECa) of the soil profile are widely used in precision agriculture practice and research. Because ECa is often strongly related to clay content, soil water holding capacity, and other soil physical properties that also relate to crop productivity, ECa maps ca...

49

Electrical Conductivity of Serpentinized Rocks to 6 Kilobars  

Microsoft Academic Search

Electrical conductivity of serpentinized rocks from the Indian Ocean ridge is 3-4 orders of magnitude higher than that of serpentine-free peridotitc, hornblende gabbro, and basalt from the same area and from the Tonga trench. The enhanced conduction is apparently characteristic of many but not all serpentine-rich rocks and may be due in part to high porosity and in part to

R. M. Stesky; W. F. Brace

1973-01-01

50

Electrical Conductivity of a Partially Ionized Gas  

Microsoft Academic Search

Electron velocity distribution functions for a partially ionized gas in a weak, steady electric field are obtained by solving the Boltzmann-Fokker-Planck equation numerically. As in the case of a fully ionized gas, the electron-electron interactions in a partially ionized gas affect the velocity distribution function and, consequently, the electrical conductivity. Electrical conductivities are calculated for a variety of assumed electron-molecule

L. C. Johnson

1967-01-01

51

Electrically conductive connection for an electrode  

DOEpatents

An electrically conductive connection for an electrode assembly of an electrolyte cell in which aluminum is produced by electrolysis in a molten salt is described. The electrode assembly comprises an electrode flask and a conductor rod. The flask has a collar above an area of minimum flask diameter. The electrically conductive connection comprises the electrode flask, the conductor rod and a structure bearing against the collar and the conductor rod for pulling the conductor rod into compressive and electrical contact with the flask.

Hornack, Thomas R. (Lower Burrell, PA); Chilko, Robert J. (Lower Burrell, PA)

1986-01-01

52

Prediction of unsaturated soil hydraulic conductivity with electrical conductivity  

Microsoft Academic Search

Soil hydraulic conductivity (K) varies greatly with matric potential (h) and exhibits a high variability at the field scale. However, this key property for estimating water flux in soils is difficult to measure. In contrast, soil electrical conductivity (?) is easier to measure and is influenced by the same parameters affecting K. We derive a simple relationship between ? and

Claude Doussan; Stéphane Ruy

2009-01-01

53

Sprayable electrically conductive polymer concrete coatings  

NASA Astrophysics Data System (ADS)

A sprayable electrically conductive polymer concrete coating for vertical and overhead applications has been developed. The technology, in conjunction with impressed current cathodic protection, can be used to prevent corrosion of the embedded reinforcing steel in concrete girders, piers, columns, and beams. A formulation of an electrically conductive polymer concrete, which holds the conductive filler in suspension and can be sprayed in thin uniform coatings, was developed.

Fontana, J. J.; Reams, W.; Elling, D.

1985-08-01

54

Electrical conduction through a monatomic surface step  

Microsoft Academic Search

We have succeeded in measuring resistance across a single atomic step at electrical conduction through a monatomic-layer metal on a crystal surface. Using independent methods of direct electrical conductivity measurement with four-tip scanning tunneling microscope probes and scanning tunneling spectroscopy observation, the conductivity across a monatomic step was found to be about 5 × 103 Omega -1m-1. Through analyses of

I. Matsuda; T. Hirahara; M. Ueno; R. Hobara; S. Hasegawa

2006-01-01

55

Electrical Conductivity in Narrow Energy Bands  

Microsoft Academic Search

The electrical conductivity for a system of electrons described by the single-band Hubbard Hamiltonian is studied. An expression for the electrical conductivity that is applicable in the narrow-band regime, i.e., the bandwidth Delta, much smaller than intra-atomic Coulomb repulsion I is derived. It is shown that the conductivity vanishes at T=0 to first order in DeltaI for one electron per

Robert A. Bari; David Adler; Robert V. Lange

1970-01-01

56

Theory of electrical conductivities of ferrogels  

Microsoft Academic Search

Conductive organic polymers can be formulated with polymers that incorporate fine dispersed metallic particles. In this work, we present a general model for ferrogels which are chemically cross-linked polymer networks swollen with a ferrofluid. Our aim is to study the effect of the shape and\\/or material (conductivity) anisotropy on the effective electrical conductivity of the ferrogel in the presence of

J. P. Huang

2004-01-01

57

Electrical conductivity of tetragonal stabilized zirconia  

Microsoft Academic Search

The electrical conductivity change on annealing for tetragonal stabilized zirconia (TZP) was studied with the help of a.c. impedance dispersion analysis techniques. The dependences of the conductivity on annealing time at 1000 ° C and on temperature cycling between room temperature and 1000 ° C were investigated. A decrease in conductivity of about 30% at 1000 ° C of TZP

O. Yamamoto; Y. Takeda; R. Kanno; K. Kohno

1990-01-01

58

Electrical conductivity effects in polyethylene terephthalate films  

NASA Astrophysics Data System (ADS)

Electrical conductivity effects in biaxially stretched polyethylene terephthalate (PET) films of 6 ?m thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range 10-2-106 Hz and at temperatures higher than the glass transition temperature (~85 °C) up to 190 °C. The formalisms of complex permittivity, electric modulus, and impedance were employed to analyze the experimental data. The results are discussed in terms of dc conductivity, conductivity current relaxation, interfacial Maxwell-Wagner-Sillars polarization, ? peak, space-charge polarization, and electrode polarization. They are compared with the predictions of models for the electrical and dielectric properties of ion-conducting polymers. The dc conductivity values determined from dc measurement, from ac conductivity plots and from complex impedance plots agree well with each other. Their temperature dependence is described by the Vogel-Tammann-Fulcher equation and classifies PET as a fragile system.

Neagu, E.; Pissis, P.; Apekis, L.

2000-03-01

59

Laboratory Electrical Conductivity Measurement of Mantle Minerals  

Microsoft Academic Search

Electrical conductivity structures of the Earth’s mantle estimated from the magnetotelluric and geomagnetic deep sounding\\u000a methods generally show increase of conductivity from 10?4–10?2 to 100 S\\/m with increasing depth to the top of the lower mantle. Although conductivity does not vary significantly in the lower\\u000a mantle, the possible existence of a highly conductive layer has been proposed at the base of

Takashi Yoshino

2010-01-01

60

Electrical Resistance Measurement of Conductive Flooring.  

National Technical Information Service (NTIS)

Methods for measuring the electrical resistance of conductive flooring at hospitals and ordnance activities are discussed. It is recommended that the method of the National Fire Protection Association Standard 56A be used, with minor modifications, for al...

P. J. Hearst

1973-01-01

61

Characterization of High Temperature Electrically Conducting Oxides.  

National Technical Information Service (NTIS)

The goal of the investigation reported on herein was to study the interrelationships between electrical conductivity, oxidation-reduction kinetics, defect structure, and composition of n- and p-type binary and ternary transition metal oxides. The experime...

H. U. Anderson D. M. Sparlin

1984-01-01

62

Improvement in Electrical Conductivity of Polypyrrole.  

National Technical Information Service (NTIS)

Preparation and stretching of highly stretchable polypyrrole films were studied in an attempt to enhance their electrical conductivity. The films were prepared by electrochemical oxidation of pyrrole in 99% aqueous propylene carbonate containing tetraethy...

K. Iwata

1984-01-01

63

Wire Assembly for Electrically Conductive Circuits.  

National Technical Information Service (NTIS)

A wire assembly for electrically conductive circuits, the assembly comprising a circuit conductor wire having a coating of insulative material thereon, a shielding foil wrapped at least partially around the coating and having a leg portion extending outwa...

W. T. Schneider

1992-01-01

64

Electrical conductivity of the continental crust  

NASA Astrophysics Data System (ADS)

Geophysical measurements indicate that the Earth's continental lower crust has a high electrical conductivity for which no simple cause has been found. Explanation usually relies on either saline fluids saturating the pores, or interconnected highly conducting minerals such as graphite, Fe/Ti oxides and sulfides, providing conducting pathways. Attempts in the laboratory to clarify the problem have, hitherto, been unable to recreate conditions likely to be present at depth by controlling the confining pressure and pore fluid pressure applied to a rock saturated with saline fluids at temperatures between 270 C and 1000 C. Here we report conductivity data obtained using a cell designed to make such measurements on rocks saturated with saline fluids. Our results show that the conductivity of saturated samples of acidic rocks is explicable entirely in terms of conduction through the pore fluid whereas the conductivity of saturated basic rocks requires the presence of an additional conduction mechanism(s). We have used the experimental data to construct electrical conductivity/depth profiles for the continental crust, which, when compared with profiles obtained from magnetotelluric observations, demonstrate that a mid to lower crust composed of amphibolite saturated with 0.5 M NaCl shows electrical conductivities sufficient to explain conductivity/depth profiles for the continental crust inferred from geophysical measurements.

Glover, Paul W. J.; Vine, F. J.

1994-11-01

65

Electrically conductive and thermally conductive materials for electronic packaging  

NASA Astrophysics Data System (ADS)

The aim of this dissertation is to develop electrically or thermally conductive materials that are needed for electronic packaging and microelectronic cooling. These materials are in the form of coatings and are made from pastes. The research work encompasses paste formulation, studying the process of converting a paste to a conductive material, relating the processing conditions to the structure and performance, and evaluating performance attributes that are relevant to the application of these conductive materials. The research has resulted in new information that is valuable to the microelectronic industry. Work on electrically conductive materials emphasizes the development of electrical interconnection materials in the form of air-firable glass-free silver-based electrically conductive thick films, which use the Ti-Al alloy as the binder and are in contrast to conventional films that use glass as the binder. The air-firability, as enabled by minor additions of tin and zinc to the paste, is in contrast to previous glass-free films that are not firable. The recommended firing condition is 930°C in air. The organic vehicle in the paste comprises ethyl cellulose, which undergoes thermal decomposition during burnout of the paste. The ethyl cellulose is dissolved in ether, which facilitates the burnout. Excessive ethyl cellulose hinders the burnout. A higher heating rate results in more residue after burnout. The presence of silver particles facilitates drying and burnout. Firing in air gives lower resistivity than firing in oxygen. Firing in argon gives poor films. Compared to conventional films that use glass as the binder, these films, when appropriately fired, exhibit lower electrical resistivity (2.5 x 10-6 O.cm) and higher scratch resistance. Work on thermally conductive materials addresses thermal interface materials, which are materials placed at the interface between a heat sink and a heat source for the purpose of improving the thermal contact. Heat dissipation is the most critical problem in the microelectronic industry. This work emphasizes the development of thermal interface materials in the form of phase change materials, namely paraffin wax, which melts at 48°C. The addition of boron nitride particles to the wax improves the performance, as indicated by the thermal contact conductance between copper surfaces. The melting of the wax improves the conformability of the thermal interface material, thereby enhancing the conductance. Pressure applied in the direction perpendicular to the plane of the interface also enhances the conductance. With 15 wt. % BN and a pressure of 0.3 MPa, a thermal contact conductance comparable to that attained by using solder (applied in the molten state) as the thermal interface material has been attained.

Liu, Zongrong

66

Electrically conductive connection for an electrode  

DOEpatents

An electrically conductive connection for an electrode assembly of an electrolyte cell in which aluminum is produced by electrolysis in a molten salt is described. The electrode assembly comprises an electrode flask and a conductor rod. The flask has a collar above an area of minimum flask diameter. The electrically conductive connection comprises the electrode flask, the conductor rod and a structure bearing against the collar and the conductor rod for pulling the conductor rod into compressive and electrical contact with the flask. 2 figs.

Hornack, T.R.; Chilko, R.J.

1986-09-02

67

Silver migration control in electrically conductive adhesives  

Microsoft Academic Search

Although conductive adhesives have been studied for many years as a lead-free alternative in electronic industry, applications of electrically conductive adhesives (ECAs) for electronic interconnect are limited to low voltage display driver devices. This is due to the serious concerns associated with the long-term reliability and high voltage application issues caused by the silver migration. In this study, a novel

Yi Li; C. P. Wong

2006-01-01

68

Electrical conduction in amorphous titanium nitride films  

Microsoft Academic Search

Charge transport measurements in disordered semiconductors and insulators have been of considerable interest because they can provide information regarding the electronic structure of these materials [1-3]. The study of direct current conduction in thin dielectric films is of importance in thin film applications. Exhaustive work has been done on electrical conduction phenomena in a variety of amorphous and crystalline dielectrics

Bellan Babuji; C. Balasubramanian; M. Radhakrishnan

1983-01-01

69

Electrical conductivity in sprite streamer channels  

NASA Astrophysics Data System (ADS)

We study the electrical conductivity of a sprite streamer channel at three different altitudes (63 km, 70 km and 80 km). We discuss the hypothesis that the electrical conductivity stays constant along the full length of a streamer channel, contrary to expectations based on scaling laws. We then apply this hypothesis and extrapolations from a numerical electrodynamical simulation to study the air plasma kinetics after the passage of a streamer. We test two possible scenarios for the physical origin of trailing sprite emissions: a single pulse and a single pulse with a delayed re-enhancement of the electric field up to the breakdown value. Our simulations show that VLF observations agree with persistent electric fields in the sprite that last several milliseconds and that associative detachment of O- ions may significantly affect the atmospheric conductivity in the presence of sprites.

Gordillo-Vázquez, F. J.; Luque, A.

2010-08-01

70

Electrical conductivity of acidic chloride solutions  

NASA Astrophysics Data System (ADS)

The electrical conductivities of aqueous solutions in the system HCl-MCln (where M = K, Na, Mg, Ni, or Cd) were measured at different temperatures. The equivalent electrical conductivity of H+ was calculated on the basis of simple assumptions for these solutions, and show an inverse relationship with water activity in these solutions. The results obtained by varying temperatures, solute ratios, and ionic strength on the electrical conductivity were found to be consistent with a proton jump mechanism for the H+ ion, where the activity of water is the most significant parameter affecting its equivalent conductance, and a viscous (Stokes’ law) drag mechanism (i.e., Walden’s rule is obeyed) for other ions found in acidic solutions.

Majima, Hiroshi; Peters, Ernest; Awakura, Yasuhiro; Park, Sung Kook; Aoki, Masami

1988-02-01

71

Theory of Electrical Conductivities of Ferrogels  

Microsoft Academic Search

Conductive organic polymers can be formulated with polymers that incorporate\\u000afine dispersed metallic particles.\\u000a In this work, we present a general model for ferrogels which are chemically\\u000across-linked polymer networks swollen with a ferrofluid. Our aim is to study\\u000athe effect of the shape and\\/or material (conductivity) anisotropy on the\\u000aeffective electrical conductivity of the ferrogel in the presence of

J. P. Huang; Max Planck

2004-01-01

72

Electric conducting cable insensitive to nuclear radiation  

SciTech Connect

Electrical conducting cable which is insensitive to nuclear radiation comprising at least one conductive core, at least one layer of an insulating substance surrounding said conductive core and at least one conductive sheath surrounding said insulating layer, wherein the diameter phi D of the sheath, the diameter phi B of the conductive core, the diameter of phi C of the insulating layer are linked by the equation: f1 representing the beta - radiation fraction from the core reaching the sheath, f2 representing the beta - radiation fraction from the sheath which reaches the core, the insulating substance being constituted by a mixture of at least two metal oxides.

Petitcolas, H.

1982-08-17

73

How to Understand Apparent Scale-Effects in the Hydraulic Conductivity  

NASA Astrophysics Data System (ADS)

As noted in the session description, field-scale hydraulic conductivity measurements tend to yield increasing K with increasing system size. It is possible, however, to prove that the connectivity of highly conducting regions can not increase with increasing system size (producing the increase in K), as this would imply that relevant correlation functions would increase with scale, or that probabilities less than or equal to one could be multiplied together with an increase in value. Continuum percolation theory can be applied to demonstrate that the hydraulic conductivity is actually independent of scale, at best. Two examples are given: 1) fractal media, and 2) upscaling with nested heterogeneity. The reasons for conclusions opposite to theory (or experimental results) relate typically in case 1) to biased or incomplete statistics, and in case 2) to incorrect theoretical inference from using, e.g., stochastic theories, such as the Matheron conjecture or related results. A simple explanation for the apparent results is that percolation on a continuum (from the pore scale to geologic scales) is guaranteed with critical volume fractions between ca. 3% and 20%, meaning that the effective K of a medium is defined by a value, which, in the 80th to the 97th percentile, may be far into the tail of the distribution. If this tail is inappropriately sampled or weighted, there is no easy way to predict the large value of the effective K.

Hunt, A. G.

2002-12-01

74

Electrical conductivity of high-purity zinc  

Microsoft Academic Search

Summary  Electrical conductivity properties of high-purity zinc (better than 99.9999%) have been studied at low temperatures. By analysing\\u000a the resistivity ratiovs. temperature curve, it has been possible to deduce an approximate value of 175 °K for the Debye temperature of zinc. From\\u000a the data deduced by the study of thickness effect on electron scattering a number of electricity carriers of 0.25±0.05

A. Desalvo; P. Gondi; F. A. Levi; F. Zignani

1964-01-01

75

Electrical Characterization of Organic Conducting Polymers  

NASA Astrophysics Data System (ADS)

As Moore's Law drives the silicon semiconductor industry to its limits, organic conducting polymers have been explored on a small scale as a possible solution to the breakdown of silicon. Here, the electrical properties of two organic polymers were measured using nanopore and micron-sized devices. In this electrical characterization, polypyrrole was found to exhibit hopping conduction, and both polypyrrole and polyaniline yield nonlinear I-V curves and degradation after sweeps of high voltage. Consequently, these organic polymers and possibly others may have only limited applications in the future semiconductor industry.

Windsor, Lindsay

2006-03-01

76

Electrically conductive containment vessel for molten aluminum  

DOEpatents

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Holcombe, Cressie E. (Knoxville, TN); Scott, Donald G. (Oak Ridge, TN)

1985-01-01

77

Electrically conductive containment vessel for molten aluminum  

DOEpatents

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal 10 borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Holcombe, C.E.; Scott, D.G.

1984-06-25

78

Partial-melt electrical conductivity: Influence of melt composition  

SciTech Connect

The electrical conductivity of a partial melt is influenced by many factors, including melt conductivity, crystalline conductivity, and melt fraction, each of which is influenced by temperature. We have performed measurements of bulk conductivity as a function of temperature of an Fo{sub 80}-basalt partial melt between 684{degree} and 1244{degree}C at controlled oxygen fugacity. Melt fraction and composition variations with temperature calculated using MELTS [Ghiorso and Sack, 1995] indicate that the effect on melt conductivity of changing melt composition is balanced by changes in temperature (T). Thus bulk conductivity as a function of T or melt fraction in this system can be calculated assuming a constant melt conductivity. The bulk conductivity is well modeled by simple parallel calculations, by the Hashin-Shtrikman upper bound, or by Archie{close_quote}s law ({sigma}{sub partial melt}/{sigma}{sub melt}=C{sub 1}X{sub m}{sup n}). We estimate apparent values of the Archie{close_quote}s law parameters between 1150{degree} and 1244 {degree}C as C{sub 1}=0.73{plus_minus}0.02 and n=0.98{plus_minus}0.01. Estimates of the permeability of the system are obtained by using an electrical conductivity-critical scale length relationship and range from {approximately}10{sup {minus}14} to 10{sup {minus}18} m{sup 2}, comparing favorably with previously published values. {copyright} 1999 American Geophysical Union

Roberts, J.J. [Lawrence Livermore National Laboratory, Livermore, California (United States); Tyburczy, J.A. [Department of Geology, Arizona State University, Tempe (United States)

1999-04-01

79

Ionic surface electrical conductivity in sandstone  

NASA Astrophysics Data System (ADS)

Recent analyses of complex conductivity measurements have indicated that high-frequency dispersions encountered in rocks saturated with low-salinity fluids are due to ionic surface conduction and that the form of these dispersions may be dependent upon the nature of the pore and crack surfaces within the rock (Ruffet et al., 1991). Unfortunately, the mechanisms of surface conduction are not well understood, and no model based on rigorous physical principles exists. This paper is split into two parts: an experimental section followed by the development of a theoretical description of adsorption of ions onto mineral surfaces. We have made complex conductivity measurements upon samples of sandstone saturated with a range of different types and concentrations of aqueous solution with a frequency range of 20 Hz to 1 MHz. The frequency dependence of complex conductivity was analyzed using the empirical model of Cole and Cole (1941). The 'fractal' surface models of Le Mehaute and Crepy (1983), Po Zen Wong (1987), the Ruffet el at. (1991) were used to calculate apparent fractal pore surface dimensions for samples saturated with different solution types and concentrations. These showed a pronounced decrease of apparent fractal surface dimension with decreasing electrolyte concentration and a decrease of apparent fractal dimension with increasing relative ionic radius of the dominant cation in solution. A model for ionic surface concentration (ISCOM I) has been developed as the first step in producing a rigorous physicochemical model of surface conduction in quartz-dominated rocks. The results from ISCOM I show that quartz surfaces are overwhelmingly dominated by adsorbed Na(+) when saturated with NaCl solutions of salinities and pH found in actual geological situations. ISCOM I also shows that the concentration threshold for dominance of surface conduction over bulk conduction is aided by depletion of ions from the bulk fluid as a result of their adsorption onto the mineral surfaces as well as by changes in the ionic mobility in the surface conduction double-layer as the wetting solution becomes more dilute.

Glover, Paul W. J.; Meredith, Philip G.; Sammonds, Peter R.; Murrell, Stanley A. F.

1994-11-01

80

Towards electrically conductive, self-healing materials  

Microsoft Academic Search

A novel class of organometallic polymers comprising N-heterocyclic carbenes and transition metals was shown to have potential as an electrically conductive, self-healing material. These polymers were found to exhibit conductivities of the order of 10K3 Sc mK1 and showed structurally dynamic characteristics in the solid-state. Thin films of these materials were cast onto silicon wafers, then scored and imaged using

Kyle A. Williams; Andrew J. Boydston; Christopher W. Bielawski

2007-01-01

81

Electrical conductance of some cellulose derivatives  

Microsoft Academic Search

The interrelation between the electrical conductance, s and some chemically modified cellulose molecule produced through partial substitution of the hydroxyl groups by different groups namely, acetate, methoxyl, carboxymethyl and sodium carboxymethyl has been studied in the temperature ranges 283–333 k. The results show that s of the examined samples change in the descending order: sodium carboxymethyl cellulose >carboxymethyl cellulose >methyl

Mohamed M. Abdel Moteleb

1992-01-01

82

Electric conductivity measurement of oxides melts  

NASA Astrophysics Data System (ADS)

In spite of the variety of existing processes of the oxide induction skull melting, electric and thermal properties of oxides melts are practically unknown. On the other hand, liquid-phase synthesis of Hi-Tech oxide materials such as new ceramics, single crystals and glasses requires the knowledge of melt properties up to 3700 K. Since the electric conductivity is a main physical property, which influences the melt power consumption at induction heating, the study of the electric conductivity temperature dependence is necessary. The principle and the technical realization of electric conductivity measurements in melts are presented. The approach is based on the induction melting by the cold crucible technology and on an inverse electromagnetic problem solution. Analysis of the method accuracy with reference to input data errors is presented. To enhance the Ill-posed problem, a set of equations is solved. The conductivity of aluminium oxide melts for temperatures up to 3223 K is also considered. Tables 2, Figs 6, Refs 17.

Poznyak, I.; Pechenkov, A.; Shatunov, A.

2007-06-01

83

DC electrical conductivity study of cerium doped conducting glass systems  

NASA Astrophysics Data System (ADS)

The glass samples of composition 60V2O5-5P2O5-(35-x)B2O3-xCeO2, (1 <= x <= 5) were prepared by the conventional melt quench method. The samples were characterized by X-ray diffraction and thermo gravimetric-differential thermal analysis. The glass transition temperature and crystallization temperature determined from TG-DTA analysis. The DC electrical conductivity has been carried out in the temperature range 303-473 K. The maximum conductivity and minimum activation energy were found to be 0.039 Scm-1 and 0.15 eV at 473 K for x=1, respectively.

Barde, R. V.; Waghuley, S. A.

2013-06-01

84

Dislocation electrical conductivity of synthetic diamond films  

SciTech Connect

A relationship between the electric resistance of single-crystal homoepitaxial and polycrystalline diamond films and their internal structure has been investigated. It is established that the electrical conductivity of undoped homoepitaxial and polycrystalline diamond films is directly related to the dislocation density in them. A relation linking the resistivity {rho} ({approx}10{sup 13}-10{sup 15} {omega} cm) with the dislocation density {gamma} ({approx}10{sup 14}-4 x 10{sup 16} m{sup -2}) is obtained. The character of this correlation is similar for both groups of homoepitaxial and polycrystalline diamond films. Thin ({approx}1-8 {mu}m) homoepitaxial and polycrystalline diamond films with small-angle dislocation boundaries between mosaic blocks exhibit dislocation conductivity. The activation energy of dislocation acceptor centers was calculated from the temperature dependence of the conductivity and was found to be {approx}0.3 eV. The conduction of thick diamond films (h > 10 {mu}m) with the resistivity {rho} {approx} 10{sup 8} {omega} cm is determined by the conduction of intercrystallite boundaries, which have a nondiamond hydrogenated structure. The electronic properties of the diamond films are compared with those of natural semiconductor diamonds of types IIb and Ic, in which dislocation acceptor centers have activation energies in the range 0.2-0.35 eV and are responsible for hole conduction.

Samsonenko, S. N., E-mail: snsamsonenko@mail.ru; Samsonenko, N. D. [Donbass National Academy of Civil Engineering and Architecture (Ukraine)

2009-05-15

85

Electrical conductivity of metal powders under pressure  

NASA Astrophysics Data System (ADS)

A model for calculating the electrical conductivity of a compressed powder mass consisting of oxide-coated metal particles has been derived. A theoretical tool previously developed by the authors, the so-called `equivalent simple cubic system', was used in the model deduction. This tool is based on relating the actual powder system to an equivalent one consisting of deforming spheres packed in a simple cubic lattice, which is much easier to examine. The proposed model relates the effective electrical conductivity of the powder mass under compression to its level of porosity. Other physically measurable parameters in the model are the conductivities of the metal and oxide constituting the powder particles, their radii, the mean thickness of the oxide layer and the tap porosity of the powder. Two additional parameters controlling the effect of the descaling of the particle oxide layer were empirically introduced. The proposed model was experimentally verified by measurements of the electrical conductivity of aluminium, bronze, iron, nickel and titanium powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases.

Montes, J. M.; Cuevas, F. G.; Cintas, J.; Urban, P.

2011-12-01

86

Electrical conductivity of acidic sulfate solution  

NASA Astrophysics Data System (ADS)

The electrical conductivities of the aqueous solution system of H2SO4-MSO4 (involving ZnSO4, MgSO4, Na2SO4, and (NH4)2SO4), reported by Tozawa et al., were examined in terms of a (H2O) and H+ ion concentration. The equations to compute the concentrations of various species in aqueous sulfuric acid solutions containing metal sulfates were derived for a typical example of the H2SO4-ZnSO4-MgSO4-(Na2SO4)-H2O system. It was found that the H+ ion concentrations in concentrated sulfuric acid solutions corresponding to practical zinc electrowinning solutions are very high and remain almost constant with or without the addition of metal sulfates. The addition of metal sulfates to aqueous sulfuric acid solution causes a decrease in electrical conductivity, and this phenomenon is attributed to a decrease in water activity, which reflects a decrease in the amount of free water. The relationship between conductivity and water activity at a constant H+ ion concentration is independent of the kind of sulfates added. On the other hand, any increase in H+ ion concentration results in an increase in electrical conductivity. A novel method for the prediction of electrical conductivity of acidic sulfate solution is proposed that uses the calculated data of water activity and the calculated H+ ion concentration. Also, the authors examined an extension of the Robinson-Bower equation to calculate water activity in quarternary solutions based on molarity instead of molality, and found that such calculated values are in satisfactory agreement with those determined experimentally by a transpiration method.

Majima, Hiroshi; Peters, Ernest; Awakura, Yasuhiro; Park, Sung Kook

1987-03-01

87

Electric conductance of highly selective nanochannels  

NASA Astrophysics Data System (ADS)

We consider electric conductance through a narrow nanochannel in the thick-double-layer limit, where the space-charge Debye layers adjacent to the channel walls overlap. At moderate surface-charge densities the electrolyte solution filling the channel comprises mainly of counterions. This allows to derive an analytic closed-form approximation for the channel conductance, independent of the salt concentration in the channel reservoirs. The derived expression consists of two terms. The first, representing electromigratory transport, is independent of the channel depth. The second, representing convective transport, depends upon it weakly.

Schnitzer, Ory; Yariv, Ehud

2013-05-01

88

Electric conductance of highly selective nanochannels.  

PubMed

We consider electric conductance through a narrow nanochannel in the thick-double-layer limit, where the space-charge Debye layers adjacent to the channel walls overlap. At moderate surface-charge densities the electrolyte solution filling the channel comprises mainly of counterions. This allows to derive an analytic closed-form approximation for the channel conductance, independent of the salt concentration in the channel reservoirs. The derived expression consists of two terms. The first, representing electromigratory transport, is independent of the channel depth. The second, representing convective transport, depends upon it weakly. PMID:23767659

Schnitzer, Ory; Yariv, Ehud

2013-05-09

89

Mechanism of electrical conductivity of jet fuels  

Microsoft Academic Search

The temperature dependence of the electrical conductivity and dynamic viscosity of jet fuels has been investigated for commercial jet fuels RT, TS-1, T-1, and T-6, all of which have initial crystallization temperatures below -60 degrees C. The data show that in the range from -35 degrees to +80 degrees C, for the RT, TS-1, and T-1 fuels, this relationship is

A. I. Belousov; E. M. Bushueva

1986-01-01

90

Wire assembly for electrically conductive circuits  

NASA Astrophysics Data System (ADS)

A wire assembly for electrically conductive circuits is described. The assembly is comprised of a circuit conductor wire having a coating of insulative material thereon, a shielding foil wrapped at least partially around the coating and having a leg portion extending outwardly from the coating, a shield conductor wire fixed to the shielding foil, and an insulative outer layer enclosing the shielding foil and the shield conductor wire.

Schneider, Walter T.

1992-04-01

91

Electrical conductivity of metal powders under pressure  

Microsoft Academic Search

A model for calculating the electrical conductivity of a compressed powder mass consisting of oxide-coated metal particles\\u000a has been derived. A theoretical tool previously developed by the authors, the so-called ‘equivalent simple cubic system’,\\u000a was used in the model deduction. This tool is based on relating the actual powder system to an equivalent one consisting of\\u000a deforming spheres packed in

J. M. Montes; F. G. Cuevas; J. Cintas; P. Urban

92

Damage Detection in Electrically Conductive Structures  

NASA Astrophysics Data System (ADS)

High-technology systems are in need of structures that perform with increased functionality and a reduction in weight, while simultaneously maintaining a high level of performance and reliability. To accomplish this, structural elements must be designed more efficiently and with increased functionality, thereby creating multifunctional structures (MFS). Through the addition of carbon fibers, nanotubes, or particles, composite structures can be made electrically conductive while simultaneously increasing their strength and stiffness to weight ratios. Using the electrical properties of these structures for the purpose of damage detection and location for health and usage monitoring is of particular interest for aerospace structures. One such method for doing this is Electrical Impedance Tomography (EIT). With EIT, an electric current is applied through a pair of electrodes and the electric potential is recorded at other monitoring electrodes around the area of study. An inverse solution of the governing Maxwell equations is then required to determine the conductivities of discrete areas within the region of interest. However, this method is nearly ill-posed and computationally intensive as it focuses on imaging small changes in conductivity within the region of interest. For locating damage in a medium with an otherwise homogeneous conductivity, an alternative approach is to search for parameters such as the damage location and size. Towards those ends, this study develops an Artificial Neural Network (ANN) to determine the state of an electrically conductive region based on applied reference current and electrical potentials at electrodes around the periphery of the region. A significant benefit of the ANN approach is that once trained, the solution of an inverse problem does not require costly computations of the inverse problem. This method also takes advantage of the pattern recognition abilities of neural networks and is a robust solution method in the presence of signal noise. The network is based on a two-tier approach where the coarse location of the damage is first located within given regions using a Learning Vector Quantization (LVQ) network. Once the approximate location is known, the second step is to apply a more refined feed-forward back-propagation (FFBP) ANN that utilizes the current and electric potential electrodes that focus on that region. In this manner, the resolution of the prediction scheme is increased. To train both the LVQ and FFBP networks, instead of time consuming and perhaps for large space structures, unfeasible experiments, a computational model is developed. The training function for the ANN is based on a finite element solution of the region and the applied boundary conditions. The inputs to the network are thus the location of the current electrodes and the corresponding electric potential values around the periphery and the network targets are the damage location and size. Future work will focus on the further development of the two-tier ANN, extension of the scheme for plural defects, and on the experimental validation of the computational training model for materials with isotropic and anisotropic conductivity.

Anderson, Todd A.

2002-12-01

93

The electrical conductivity of sodium polysulfide melts  

SciTech Connect

The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na{sub 2}S{sub 4} and Na{sub 2}S{sub 5} were measured as a function of temperature (range: 300 to 360{degree}C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.

Meihui Wang.

1992-06-01

94

Electrical Noise in Individual Conducting Polymer Nanowires  

NASA Astrophysics Data System (ADS)

Electrical property characterizations of conducting polymer nanostructures have been limited primarily to resistance measurements. Electrical noise is one aspect that is usually overlooked, yet critical to their device performance. Moreover, electrical noise is more sensitive to the polymer doping and microstructure than resistance, which makes it particularly interesting for sensor applications. In this talk, we will present the results on the electrical noise measurements of individual multisegmented electrodeposited nanowires based on Poly(3,4-ethylenedioxythiophene (PEDOT) [1]. The polymer was electrochemically doped with either poly(4-styrenesulfonic acid) (PSS) or perchlorate (ClO4). The nanowires had gold contacts on both ends and were measured in four-point and two-point configurations. We found that the electrical noise behavior is typical of 1/f noise, with a spectral density that depends on the polymer structure and is affected by the ambient conditions. Our data show that the contact noise represents a significant contribution to the total noise level. We will discuss the interpretation of these results assuming that the polymer is a disordered conductor. [1] Cao et al., Nano Letters Article ASAP

Kovalev, Alexey; Cao, Yanyan; Mayer, Theresa; Mallouk, Thomas

2009-03-01

95

[The electrical conductivity of triggered lightning channel].  

PubMed

Spectra of return strokes for artificial triggered lightning were obtained by optical multi-channel analyzer (OMA) in Shandong region. Compared with previous spectra of natural lightning, additional lines of ArI 602.5 nm and ArII 666.5 nm were observed. Under the model of local thermodynamic equilibrium, electronic temperatures of the lightning channel plasma were obtained according to the relative line intensities. Meanwhile, with semi-empirical method the electron density was obtained by Halpha line Stark broadening. In combination with plasma theory, electrical conductivity of the lightning channel has been calculated for the first time, and the characteristic of conductivity for lightning channel was also discussed. The relation between the electrical conductivity of channel and the return stroke current was analyzed, providing reference data for further work on computing return stroke current. Results show that the lightning channel is a good conductor, and electrons are the main carrier of channel current. The brightness of artificial triggered lightning channel is usually higher than that of natural lightning, and its current is smaller than that of the natural lightning. PMID:18306764

Zhang, Hua-ming; Yuan, Ping; Su, Mao-gen; Lü, Shi-hua

2007-10-01

96

NOVEL GRAPHITE SALTS AND THEIR ELECTRICAL CONDUCTIVITIES  

SciTech Connect

A set of novel first stage graphite salts of general formula C{sub 8}{sup +}MF{sub 6}{sup -} has been prepared (M = Os, Ir, As). Single crystal X-ray diffraction studies indicate that these salts are hexagonal with a {approx} 4.9 and c {approx} 8.1 {angstrom}. The unit cell volume indicates that the anions are closely packed in the galleries. Platinum hexafluoride, which is the most powerful oxidizer of the third transition series, forms a first stage compound, which analytical, structural, and magnetic studies establish as C{sub 12}{sup 2+}PtF{sub 6}{sup 2-}. In this salt the anions are not close packed, but the electron withdrawal from the graphite planes is greater than for the C{sub 8}{sup +}MF{sub 6}{sup -} series. The variation in the electrical conductivity (in the a-b plane), as a function of composition, has been investigated with the OsF{sub 6}, IrF{sub 6}, PtF{sub 6} and AsF{sub 5} intercalates. For OsF{sub 6} and IrF{sub 6}, the conductance per plane of graphite is found to be a maximum at approximately C{sub 24}MF{sub 6} (second stage); the conductivity being an order of magnitude greater than that of the parent material. Intercalation beyond C{sub 24}MF{sub 6} leads to a marked decrease in conductivity. C{sub 8}MF{sub 6} is comparable in conductivity with the parent graphite. This behavior contrasts with the graphite/AsF{sub 5} system in which a steady increase in conductance per graphite plane with increasing AsF{sub 5} content is observed. For the PtF{sub 6} system, the second as well as the first stage materials are poorly conducting.

Bartlett, N.; McCarron, E.M.; McQuillan, B.W.; Thompson, T.E.

1980-02-01

97

Electrical Conductivity Calculations from the Purgatorio Code  

SciTech Connect

The Purgatorio code [Wilson et al., JQSRT 99, 658-679 (2006)] is a new implementation of the Inferno model describing a spherically symmetric average atom embedded in a uniform plasma. Bound and continuum electrons are treated using a fully relativistic quantum mechanical description, giving the electron-thermal contribution to the equation of state (EOS). The free-electron density of states can also be used to calculate scattering cross sections for electron transport. Using the extended Ziman formulation, electrical conductivities are then obtained by convolving these transport cross sections with externally-imposed ion-ion structure factors.

Hansen, S B; Isaacs, W A; Sterne, P A; Wilson, B G; Sonnad, V; Young, D A

2006-01-09

98

Optical and Electrical Properties of Conducting Electrodes  

NASA Astrophysics Data System (ADS)

Recent advances in infrared device technology require transparent conducting electrodes (TCE's) for a variety of applications. In addition to being transparent in the infrared, these electrodes need to have good dc conductivity on the order of 100 ?/square. The presence of a strong plasma edge in the near IR makes Indium-Tin Oxide, the standard TCE for the visible, not suitable for these applications. We have studied the optical and electrical properties of promising materials, such as NiRh_2O_4, InO_x, CuAlO_2, on several substrates, including glass, Sapphire, ZnSe, and Si. We make combined transmittance and reflectance measurements over the whole spectral range from far infrared through the visible, and extract the optical conductivity of these materials. Our results indicate that two materials, NiRh_2O4 and InO_x, have good IR transmission out to the limit of the ZnSe window, in addition to adequate dc conductivity.

Tache, Nacira; Drozdova, Olga; Nikolou, Maria; Tanner, David B.; Mitra, Partha; Hebard, Arthur F.; Exarhos, Gregory J.; Windisch, Charles F., Jr.; Owings, Robert R.; Holloway, Paul H.

2003-03-01

99

Electrical-conductivity testing of latex gloves  

SciTech Connect

There is an increasing awareness in the healthcare field that gloves worn for protection from hazards associated with body fluids do not always afford the protection desired. Gloves may have defects, such as holes, as they come from the manufacturer or distributor, or they may become defective during storage or use. While the numbers vary widely, failure rates for new gloves, defined as detectable holes in gloves prior to use, for unused examination gloves are reported as high as 58%. Rates as high as 7% have been reported for sterile latex gloves. Incidences of breaching the latex barrier during use vary with procedure but have been reported as high as 50%. In recent years, a number of devices have been developed to detect holes in latex gloves as they are being worn. Detection of increased electrical conductivity that takes place through the holes in the gloves is used to activate an audible alarm. The primary purpose of this research was to investigate the validity of this method for hole detection. This evaluation was accomplished with both basic laboratory equipment and commercially available instruments. We did not evaluate or critically compare the individual devices. We also investigated the use of electrical conductivity as a quality assurance (QA) procedure, and the degradation of latex gloves due to storage and exposure to laboratory atmospheres and disinfectants.

Stampfer, J.F.; Salazar, J.A.; Trujillo, A.G.; Harris, T.; Berardinelli, S.P.

1994-11-01

100

Electrical conductivity of individual carbon nanotubes  

NASA Astrophysics Data System (ADS)

THE interest in carbon nanotubes has been greatly stimulated by theoretical predictions that their electronic properties are strongly modulated by small structural variations1-8. In particular, the diameter and the helicity of carbon atoms in the nanotube shell are believed to determine whether the nanotube is metallic or a semiconductor. Because of the enormous technical challenge of making measurements on individual nanotubes, however, experimental studies have been limited mainly to bulk measurements9, which indicate only that a fraction of the nanotubes are metallic or narrow-band semiconductors10. Recently, measurements of the magneto-conductance of a single multi-shell nanotube in a two-probe configuration showed that the transport is characterized by disorder and localization phenomena11. To avoid possible ambiguities due to poor sample contacts, four-probe measurements are needed. Here we report four-probe measurements on single nanotubes made by lithographic deposition of tungsten leads across the tubes. We find that each multi-shell nanotube has unique conductivity properties. Both metallic and non-metallic behaviour are observed, as well as abrupt jumps in conductivity as the temperature is varied. The differences between the electrical properties of different nanotubes are far greater than expected. Our results suggest that differences in geometry play a profound part in determining the electronic behaviour.

Ebbesen, T. W.; Lezec, H. J.; Hiura, H.; Bennett, J. W.; Ghaemi, H. F.; Thio, T.

1996-07-01

101

An assessment of expressions for the apparent thermal conductivity of cellular materials  

Microsoft Academic Search

Diverse expressions for the thermal conductivity of cellular materials are reviewed. Most expressions address only the conductive contribution to heat transfer; some expressions also consider the radiative contribution. Convection is considered to be negligible for cell diameters less than 4 mm. The predicted results are compared with measured conductivities for materials ranging from fine-pore foams to coarse packaging materials. The

P. G. Collishaw; J. R. G. Evans

1994-01-01

102

High electric field conduction in aromatic hydrocarbons: effects of the polymerization  

Microsoft Academic Search

The electrical conduction of purified toluene in the negative tip-plane electrode geometry was studied for high electric field. Mean current-voltage characteristics and current pulses (apparent charge, frequency) were measured for different tip radii. Above a threshold electric field of 4.2±0.6 MV\\/cm, the results depended greatly on the previous use of the tip. For the first measurements made with a given

Marwan Brouche; Jean Pierre Gosse

1996-01-01

103

Electrical conductivity and thermopower of metallic helium  

NASA Astrophysics Data System (ADS)

The pair effective interionic interaction, electrical resistance, and thermopower of liquid metallic helium have been calculated over wide temperature and density ranges using the perturbation theory for the potential of electron-ion interaction. For conduction electrons, the random-phase approximation has been used taking into account the exchange interaction and correlations in the local-field approximation. The nuclear subsystem has been described by the hard-sphere model. The sphere diameter is the only parameter of the theory. The diameter and the system density at which helium is transformed from the singly ionized to doubly ionized state have been estimated based on an analysis of the pair effective interaction between helium nuclei. The case of doubly ionized helium atoms has been considered. The numerical calculations have been performed taking into account the perturbation theory in terms up to the third order. In all cases, the role of the third-order correction is significant. In the case of metallic helium, the values of the electrical resistance and its temperature dependence are characteristic of divalent simple liquid metals, as well as the dependences of the thermopower on the density and temperature.

Shvets, V. T.; Kozitskii, S. V.

2013-04-01

104

Thermal and Electrical Conductivities of Biological Fluids and Tissues.  

National Technical Information Service (NTIS)

Experimental electrical conductivities of human gastric juices, urine and bovine aqueous and vitreous humours were determined. Special cells for the determination of electrical conductivities for tissues has been designed, constructed, and tested. Experim...

H. F. Poppendiek N. D. Greene J. E. Chambers L. V. Feigenbutz P. M. Morehouse

1965-01-01

105

Form Invariant Sommerfeld Electrical Conductivity in Generalised d Dimensions  

NASA Astrophysics Data System (ADS)

The Sommerfeld electrical conductivity is calculated in d dimensions following Boltzmann kinetic approach. At T = 0, the mathematical form of the electrical conductivity is found to remain invariant in any generalised spatial (d) dimensions.

Muktish, Acharyya

2011-11-01

106

Electrically conductive, immobilized bioanodes for microbial fuel cells  

NASA Astrophysics Data System (ADS)

The power densities of microbial fuel cells with yeast cells as the anode catalyst were significantly increased by immobilizing the yeast in electrically conductive alginate electrodes. The peak power densities measured as a function of the electrical conductivity of the immobilized electrodes show that although power increases with rising electrical conductivity, it tends to saturate beyond a certain point. Changing the pH of the anode compartment at that point seems to further increase the power density, suggesting that proton transport limitations and not electrical conductivity will limit the power density from electrically conductive immobilized anodes.

Ganguli, R.; Dunn, B.

2012-07-01

107

Autumnal leaf conductance and apparent photosynthesis by saplings and sprouts in a recently disturbed northern hardwood forest  

Microsoft Academic Search

Summary  Leaf surface conductance and apparent photosynthesis were measured during late summer and autumn on saplings and sprouts of\\u000a pin cherry (Prunus pensylvanica), yellow birch (Betula alleghaniensis), American beech (Fagus grandifolia), and sugar maple (Acer saccharum) naturally revegetating a site in the northern hardwood forest 5 years following a commercial whole-tree harvest. Prior to\\u000a the disturbance (i.e., the harvest) the site

Jeffrey S. Amthor; David S. Gill; F. Herbert Bormann

1990-01-01

108

New method for electrical conductivity temperature compensation.  

PubMed

Electrical conductivity (?) measurements of natural waters are typically referenced to 25 °C (?25) using standard temperature compensation factors (?). For acidic waters (pH < 4), this can result in a large ?25 error (??25). The more the sample temperature departs from 25 °C, the larger the potential ??25. For pH < 4, the hydrogen ion transport number becomes substantial and its mode of transport is different from most other ions resulting in a different ?. A new method for determining ? as a function of pH and temperature is presented. Samples with varying amounts of H2SO4 and NaCl were used to develop the new ?, which was then applied to 65 natural water samples including acid mine waters, geothermal waters, seawater, and stream waters. For each sample, the ? and pH were measured at several temperatures from 5 to 90 °C and ?25 was calculated. The ??25 ranged from -11 to 9% for the new method as compared to -42 to 25% and -53 to 27% for the constant ? (0.019) and ISO-7888 methods, respectively. The new method for determining ? is a substantial improvement for acidic waters and performs as well as or better than the standard methods for circumneutral waters. PMID:23895179

McCleskey, R Blaine

2013-08-15

109

Magnetic flowmeter for electrically conductive liquid  

DOEpatents

A magnetic flowmeter includes first and second tube sections each having ls of non-magnetic material. The first tube is suitably connected to a process for passing a flow of an electrically conductive fluid to be measured. The second tube is established as a reference containing a still medium and is maintained at the same temperature as the first tube. A rotatable magnet assembly is disposed between the two tubes with at least two magnets attached to radially extending arms from a central shaft. Each magnet includes an air gap suitably sized to pass astraddle the diameter along a portion of the length of each of the two tubes. The magnets are provided in matched pairs spaced 180.degree. apart such that signals will be simultaneously generated in signal leads attached to each of the two tubes. By comparing the signals from the two tubes and varying the rotating speed of the magnet assembly until the signals are equal, or attain a maximum, the flow velocity of the fluid within the first tube can be determined. Through temperature monitoring and appropriate heaters, the two tubes are maintained at the same temperature.

Skladzien, Stanley B. (Elmhurst, IL); Raue, Donald J. (Naperville, IL)

1982-01-01

110

Magnetic flowmeter for electrically conductive liquid  

DOEpatents

A magnetic flowmeter includes first and second tube sections each having walls of non-magnetic material. The first tube is suitably connected to a process for passing a flow of an electrically conductive fluid to be measured. The second tube is established as a reference containing a still medium and is maintained at the same temperature as the first tube. A rotatable magnet assembly is disposed between the two tubes with at least two magnets attached to radially extending arms from a central shaft. Each magnet includes an air gap suitably sized to pass astraddle the diameter along a portion of the length of each of the two tubes. Two magnets are provided in matched pairs spaced 180/sup 0/ apart such that signals will be simultaneously generated in signal leads attached to each of the two tubes. By comparing the signals from the two tubes and varying the rotating speed of the magnet assembly until the signals are equal, or attain a maximum, the flow velocity of the fluid within the first tube can be determined. Through temperature monitoring and appropriate heaters, the two tubes are maintained at the same temperature.

Skladzien, S.B.; Raue, D.J.

1980-08-18

111

Electrically conductive polymer nanocomposites as deformation sensors  

Microsoft Academic Search

This work is related to in situ measurements of the a.c. electrical properties under large strain of composites strongly contrasted in relation to their electrical and mechanical properties. First, a RC type model has been developed to model the electrical properties of strongly heterogeneous material by the use of an improvement in the R and C models developed in the

L. Flandin; Y. Bréchet; J.-Y. Cavaillé

2001-01-01

112

Apparent intermediate K conductance channel hyposmotic activation in human lens epithelial cells.  

PubMed

This study explores the nature of K fluxes in human lens epithelial cells (LECs) in hyposmotic solutions. Total ion fluxes, Na-K pump, Cl-dependent Na-K-2Cl (NKCC), K-Cl (KCC) cotransport, and K channels were determined by 85Rb uptake and cell K (Kc) by atomic absorption spectrophotometry, and cell water gravimetrically after exposure to ouabain +/- bumetanide (Na-K pump and NKCC inhibitors), and ion channel inhibitors in varying osmolalities with Na, K, or methyl-d-glucamine and Cl, sulfamate, or nitrate. Reverse transcriptase polymerase chain reaction (RT-PCR), Western blot analyses, and immunochemistry were also performed. In isosmotic (300 mosM) media approximately 90% of the total Rb influx occurred through the Na-K pump and NKCC and approximately 10% through KCC and a residual leak. Hyposmotic media (150 mosM) decreased K(c) by a 16-fold higher K permeability and cell water, but failed to inactivate NKCC and activate KCC. Sucrose replacement or extracellular K to >57 mM, but not Rb or Cs, in hyposmotic media prevented Kc and water loss. Rb influx equaled Kc loss, both blocked by clotrimazole (IC50 approximately 25 microM) and partially by 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34) inhibitors of the IK channel KCa3.1 but not by other K channel or connexin hemichannel blockers. Of several anion channel blockers (dihydro-indenyl)oxy]alkanoic acid (DIOA), 4-2(butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)oxybutyric acid (DCPIB), and phloretin totally or partially inhibited Kc loss and Rb influx, respectively. RT-PCR and immunochemistry confirmed the presence of KCa3.1 channels, aside of the KCC1, KCC2, KCC3 and KCC4 isoforms. Apparently, IK channels, possibly in parallel with volume-sensitive outwardly rectifying Cl channels, effect regulatory volume decrease in LECs. PMID:18184876

Lauf, Peter K; Misri, Sandeep; Chimote, Ameet A; Adragna, Norma C

2008-01-09

113

Development of an angular scanning system for sensing vertical profiles of soil electrical conductivity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Apparent soil electrical conductivity (EC**a**) is typically mapped to define soil spatial variability within an agricultural field. Knowledge of the vertical variability of EC**a** is desired to define site-specific behavior of the soil profile. A Pneumatic Angular Scanning System (PASS) was develo...

114

CHARACTERIZING FIELD-SCALE SOIL VARIABILITY ACROSS THE MIDWEST WITH SOIL ELECTRICAL CONDUCTIVITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Apparent profile soil electrical conductivity (ECa) can be an indirect indicator of a number of soil physical and chemical properties. Commercially available ECa sensors can be used to efficiently and inexpensively develop the spatially dense datasets desirable for describing within-field spatial so...

115

SPATIAL SOIL VARIABILITY MAPPING USING ELECTRICAL CONDUCTIVITY SENSOR FOR PRECISION FARMING OF RICE  

Microsoft Academic Search

Accurate and inexpensive methods for measuring soil properties are required to enhance interpretation of yield maps and improve planning for precision farming strategies. The conventional soil sampling is time consuming and requires intensive laboratory analysis. Hence mapping of apparent profile of soil electrical conductivity (ECa) was developed to identify areas of contrasting soil properties. Such ECa values are surrogate measures

M. S. M. Amin; W. Aimrun; S. M. Eltaib; C. S. Chan

116

Electrical conductivity of ion-doped graphite\\/polyethersulphone composites  

Microsoft Academic Search

The electrical conductivity of polyethersulphone (PES) insulating polymer was improved by incorporation of electrically conductive graphite and ions. An initial conducting pathway of the PES\\/graphite composites was formed at lower than 3wt.% of the filler content. LiCl was found to be an effective dopant for the improvement of the electrical conductivities of the PES\\/graphite composites. By doping with 0.06wt.% of

J. Jin; S. Leesirisan; M. Song

2010-01-01

117

Development of electrically\\/thermally conducting polymer-matrix composites  

Microsoft Academic Search

Polymer-matrix composites that are (i) electrically conducting or (ii) thermally conducting but electrically insulating were developed. A goal was to enhance the conductivity, while maintaining good mechanical properties. An in-situ technology for forming an electrically conducting network in a polymer-matrix composite during composite fabrication was developed. One variation of this technology involved the use of a particulate filler that melted

Lin

1993-01-01

118

Spatial Variability of Electrical Conductivity in North Mississippi Loamy Soils  

Microsoft Academic Search

The use of non-contact electrical geophysical methods, such as electromagnetic induction (EM), to characterize and quantify spatial and temporal variations in soil properties is appealing due to low operational costs, rapid measurements, and device mobility. These methods are sensitive to soil electrical conductivity, which can vary with soil moisture, clay content, soil salinity, and the presence of electrically conductive minerals.

J. E. Twombly; C. W. Fancher; M. D. Sleep; M. S. Aufman; J. V. Holland; R. M. Holt; J. S. Kuszmaul

2004-01-01

119

The thermal and electrical conductivities of metals at high temperatures  

Microsoft Academic Search

A method of investigating the electrical and thermal conductivities of metals at high temperatures is described. The theory of the method depends upon the application of ideas which are fundamental in the study of electrical contact phenomena. The ratio of the thermal to the electrical conductivity of platinum has been determined from 1200° C to the melting point (1773° C)

M. R. Hopkins

1957-01-01

120

Electrical Conduction through Nerve and DNA  

Microsoft Academic Search

The aim of the present study was to analyse electric resistivity at different ambient temperatures between 300 to 20K in the frog sciatic nerve and salmon sperm DNA. When the electrical contacts were leaned just into the sciatic nerve, an increase of the sciatic nerve resistivity was observed for 240 K < T < 300 K and a rise of

H. Abdelmelek; A. El-May; Ben Hamouda; M. Ben Salem; J. M. Pequignot; M. Sakly

2003-01-01

121

Effective electrical and thermal conductivity of multifilament twisted superconductors  

NASA Astrophysics Data System (ADS)

The effective electrical and thermal conductivity of composite wire with twisted superconducting filaments embedded into normal metal matrix is calculated using the extension of Bruggeman method. The resistive conductivity of superconducting filaments is described in terms of symmetric tensor, whereas the conductivity of a matrix is assumed to be isotropic and homogeneous. The dependence of the resistive electrical conductivity of superconducting filaments on temperature, magnetic field, and current density is implied to be parametric. The resulting effective conductivity tensor proved to be non-diagonal and symmetric. The non-diagonal transverse-longitudinal components of effective electrical conductivity tensor are responsible for the redistribution of current between filaments. In the limits of high and low electrical conductivity of filaments the transverse effective conductivity tends to that of obtained previously by Carr. The effective thermal conductivity of composite wires is non-diagonal and radius-dependent even for the isotropic and homogeneous thermal conductivities of matrix and filaments.

Chechetkin, V. R.

2013-06-01

122

Electrically conductive articles and processes for their fabrication  

Microsoft Academic Search

This patent describes a electrically conductive articles and processes for their fabrication. They comprise a refractory substrate, a flexible electrically conductive crystalline cuprate layer, a release layer interposed between the flexible conductive cuprate layer and the substrate, the release layer being comprised of at least on of the metals of groups 8 to 11 and periods 5 and 6 of

J. M. Mir; L. S. Hung

1991-01-01

123

Electrical conductivity of fruits and meats during ohmic heating  

Microsoft Academic Search

The design of effective ohmic heaters depends on the electrical conductivity of foods. Electrical conductivities of six different fresh fruits (red apple, golden apple, peach, pear, pineapple and strawberry) and several different cuts of three types of meat (chicken, pork and beef) were determined from room temperature through to the sterilization temperature range (25–140°C). In all cases, conductivities increased linearly

Sanjay Sarang; Sudhir K. Sastry; Lynn Knipe

2008-01-01

124

The significance of terrestrial electrical conductivity variations  

Microsoft Academic Search

Induction processes are examined and the radial variation of conductivity within the earth is considered. A description of regional studies is presented, taking into account array observations, geomagnetic depth sounding, magnetotelluric surveys, controlled-source experiments, measurements at sea, and the application of linear inverse theory. Mineral and rock conductivities are discussed. Ionic conduction occurs in fluids occupying fractures and pore spaces,

G. D. Garland

1981-01-01

125

Electrical conductivity of packed particle beds  

Microsoft Academic Search

The dependence of conductivity on particle size is derived for the case of insulating particles exhibiting surface conductivity and particle-to-particle contact resistance. Experimental results obtained on glass particle beds agree well with the physical model that emphasizes surface conductivity as a controlling factor. The proportionality of the DC resistivity to the particle size proposed in the present report was verified

JAN BARES

1988-01-01

126

Partial melting and electrical conductivity anomalies in the upper mantle  

Microsoft Academic Search

For mantle regions of anomalously high electrical conductivity (greater than 0.1 S\\/m) the bulk conductivity is modeled by effective medium theory as a basalt melt fraction within a mainly olivine matrix. In order for the highly conducting melt to affect the bulk conductivity it must form interconnections, so that the very existence of mantle conductivity anomalies constitutes evidence for such

T. J. Shankland; H. S. Waff

1977-01-01

127

Thermal and Electrical Contact Conductance Studies.  

National Technical Information Service (NTIS)

Prediction of electrical and thermal contact resistance for pressed, nominally flat contacts is complicated by the large number of variables which influence contact formation. This is reflected in experimental results as a wide variation in contact resist...

S. W. Vansciver M. Nilles

1985-01-01

128

Electrical conductivity measurement on DKDP Crystals with different deuterated degrees  

NASA Astrophysics Data System (ADS)

Ten DKDP single crystals with deuterated degrees ranging from 0 to 90 % were grown by a rapid growth method. The electrical conductivities of these crystals were measured along a and c directions at room temperature. The electrical conductivity increases with the increase for deuterium content. Also, the electrical conductivities of certain crystals were measured at various temperatures ranging from 20 to 130 °C. The values of activation energy decrease as the increase of deuterium content. The present study indicates that the deuterium tunneling frequency is smaller than that of hydrogen, which may be the reason why the variation of electrical conductivity happens after the substitution of hydrogen for deuterium in KDP crystal.

Liu, Baoan; Yin, Xin; Zhao, Minglei; Zhang, Qinghua; Xu, Mingxia; Ji, Shaohua; Zhu, Lili; Zhang, Lisong; Sun, Xun; Xu, Xinguang

2012-10-01

129

Optical and Electrical Properties of Conducting Electrodes  

Microsoft Academic Search

Recent advances in infrared device technology require transparent conducting electrodes (TCE's) for a variety of applications. In addition to being transparent in the infrared, these electrodes need to have good dc conductivity on the order of 100 Omega\\/square. The presence of a strong plasma edge in the near IR makes Indium-Tin Oxide, the standard TCE for the visible, not suitable

Nacira Tache; Olga Drozdova; Maria Nikolou; David B. Tanner; Partha Mitra; Arthur F. Hebard; Gregory J. Exarhos; Charles F. Windisch Jr.; Robert R. Owings; Paul H. Holloway

2003-01-01

130

The electrical conductivity of human cerebrospinal fluid at body temperature  

Microsoft Academic Search

The electrical conductivity of human cerebrospinal fluid (CSF) from seven patients was measured at both room temperature (25 C) and body temperature (37 C). Across the frequency range of 10Hz-10 kHz, room temperature conductivity was 1.45 S\\/m, but body temperature conductivity was 1.79 S\\/m, approximately 23% higher. Modelers of electrical sources in the human brain have underestimated human CSF conductivity

Stephen B. Baumann; David R. Wozny; Shawn K. Kelly; Frank M. Meno

1997-01-01

131

Electrical conductivity of synthetic iron-bearing olivine  

Microsoft Academic Search

The electrical conduction in synthetic, dry polycrystalline, iron-bearing olivine (Fo90) was investigated as a first-order approach to the electrical conductivity in the upper mantle. This fundamental study is\\u000a of great importance to better understand the charge-transport mechanisms seen in olivine. Conduction processes in synthetic\\u000a samples are not influenced by a complex geological history in contrast to conductivity in natural olivine.

Robert J. M. Farla; C. J. Peach; S. M. ten Grotenhuis

2010-01-01

132

An Elastic Electrically-Conductive Strain Cable.  

National Technical Information Service (NTIS)

The cable includes bundles of plastic-impregnated nylon fibers acting both as strain members and strain accumulators. An inner core bundle is wound with an electrical conductor that stretches with the fibers when the cable is tensioned. The winding pitch ...

F. H. Fisher V. C. Anderson

1977-01-01

133

Electrical safety of conducted electrical weapons relative to requirements of relevant electrical standards.  

PubMed

Introduction: TASER(®) conducted electrical weapons (CEW) deliver electrical pulses that can inhibit a person's neuromuscular control or temporarily incapacitate. TASER X26, X26P, and X2 are among CEW models most frequently deployed by law enforcement agencies. The X2 CEW uses two cartridge bays while the X26 and X26P CEWs have only one. The TASER X26P CEW electronic output circuit design is equivalent to that of any one of the two TASER X2 outputs. The goal of this paper was to analyze the nominal electrical outputs of TASER X26, X26P, and X2 CEWs in reference to provisions of several international standards that specify safety requirements for electrical medical devices and electrical fences. Although these standards do not specifically mention CEWs, they are the closest electrical safety standards and hence give very relevant guidance. PMID:24110943

Panescu, Dorin; Nerheim, Max; Kroll, Mark

2013-07-01

134

High pressure electrical conductivity studies of acid doped polybenzimidazole  

Microsoft Academic Search

Electrical conductivity studies of acid doped poplybenzimidazole (PBI) and 85% phosphoric acid have been carried out. The PBI contained about 600mol% of 85% phosphoric acid and the electrical conductivity was deduced from complex impedance studies which were made at frequencies from 10 to 107Hz. Measurements were made at pressures up to 0.25 GPa and temperatures of about 25, 50 and

J. J Fontanella; M. C Wintersgill; J. S Wainright; R. F Savinell; M Litt

1998-01-01

135

SOIL AGGREGATE AND UNCERTAINTY EFFECTS ON ELECTRICAL CONDUCTIVITY SPECTRA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Vector network analyzers have been used to determine permittivity and electrical conductivity spectra in the kilohertz to gigahertz range. The objectives of this study were to determine uncertainty in the complex electrical conductivity spectra, and to examine the effect of aggregation on the spectr...

136

Electrical conductivity of carbon-nanotube/cellulose composite paper  

NASA Astrophysics Data System (ADS)

We fabricated multiwalled carbon-nanotube/cellulose composite papers and measured their temperature dependences of electrical conductivity. The dependences were described with the Sheng's fluctuation-induced tunneling (FIT) model. A possible mechanism of the electrical conduction in the composite paper was discussed in the context of the FIT model.

Tanaka, Tomo; Sano, Eiichi; Imai, Masanori; Akiyama, Kousuke

2010-03-01

137

Electrically Conductive Coatings with High Thermal Oxidative Stability and Low Thermal Conduction.  

National Technical Information Service (NTIS)

The present invention is directed to electrically conductive coatings of carbon that have high thermal oxidative stability and low thermal conduction. Coatings of the invention provide a surface resistivity to the coated substrate of 10(sup 2) ohms/square...

P. J. Glatkowski

2004-01-01

138

Models proposed to explain the electrical conductivity of mixtures made of conductive and insulating materials  

Microsoft Academic Search

The electrical conductivity of mixtures of conductive and insulating materials is reviewed. In general, the conductivity of such mixtures increases drastically at a certain concentration of the conductive component, the so-called percolation concentration. Among the parameters influencing the percolation concentration, the filler distribution, filler shape, filler\\/matrix interactions and the processing technique are the most important ones. On the basis of

F. Lux

1993-01-01

139

Partial melt in the mantle: evidence from electrical conductivity  

Microsoft Academic Search

For mantle regions of anomalously high electrical conductivity (0.1 to 1.0 S\\/m) the conductivity is modeled by effective medium theory as a basalt melt fraction within a mainly olivine matrix. In order for the highly conducting melt to affect the bulk conductivity it must form interconnections; thus the very existence of mantle conductivity anomalies constitutes evidence for such interconnections. Petrological

T. J. Shankland; H. S. Waff

1976-01-01

140

Electrically conductive lines on cellulose nanopaper for flexible electrical devices  

NASA Astrophysics Data System (ADS)

Highly conductive circuits are fabricated on nanopapers composed of densely packed 15-60 nm wide cellulose nanofibers. Conductive materials are deposited on the nanopaper and mechanically sieved through the densely packed nanofiber networks. As a result, their conductivity is enhanced to the level of bulk silver and LED lights are successfully illuminated via these metallic conductive lines on the nanopaper. Under the same deposition conditions, traditional papers consisting of micro-sized pulp fibers produced very low conductivity lines with non-uniform boundaries because of their larger pore structures. These results indicate that advanced, lightweight and highly flexible devices can be realized on cellulose nanopaper using continuous deposition processes. Continuous deposition on nanopaper is a promising approach for a simple roll-to-roll manufacturing process.

Hsieh, Ming-Chun; Kim, Changjae; Nogi, Masaya; Suganuma, Katsuaki

2013-09-01

141

Grain size effect on the electrical conductivity of clinopyroxene  

NASA Astrophysics Data System (ADS)

Complex impedance spectra of polycrystalline samples (with grain size fractions ~5-63, 63-160 and 160-250 ?m) and a single crystal sample (with orientation parallel to b), prepared from a natural megacryst augite, were measured in a piston cylinder apparatus at 10 kbar and 500-1,000°C and with a Solartron 1260 Impedance/Gain Phase analyzer over a frequency range of 0.1-106 Hz. The main charge carriers are attributed to small polarons, and the activation enthalpy is 83 ± 3 to 90 ± 3 kJ/mol. The measured electrical conductivity shows no difference between the polycrystalline and single crystal samples, suggesting independence of electrical conductivity on grain size given a change above ~5 ?m. The electrical conductivity of augite is much higher than that of olivine, indicating that, if regionally enriched, augites may lead to zones of high electrical conductivity and electrical anisotropy in the deep lithosphere.

Yang, Xiaozhi; Heidelbach, Florian

2012-06-01

142

Mantle Electrical Conductivity and the Deep Carbon Cycle  

Microsoft Academic Search

Electrical conductivity of mantle regions where volatiles are entrained at depth by subduction or where volatiles ascend from depth at hotspot and mid-ocean ridge displays anomalously high values, which exceed the conductivity expected from laboratory measurements on fluid-free mantle rocks. There is little doubt that such anomalously conductive regions image the flux of mantle fluids, which directly impacts on the

Fabrice Gaillard

2010-01-01

143

Electrical Conductivity in a Mixed-Species Biofilm  

PubMed Central

Geobacter sulfurreducens can form electrically conductive biofilms, but the potential for conductivity through mixed-species biofilms has not been examined. A current-producing biofilm grown from a wastewater sludge inoculum was highly conductive with low charge transfer resistance even though microorganisms other than Geobacteraceae accounted for nearly half the microbial community.

Lau, Joanne; Nevin, Kelly P.; Franks, Ashley E.; Tuominen, Mark T.; Lovley, Derek R.

2012-01-01

144

Electrical Conductivity in High Pressure, Dense Liquid Oxygen  

Microsoft Academic Search

Electrical conductivities of fluid oxygen were measured between 30 and 200 GPa at a few 1000 K. These conditions were achieved with a reverberating shock wave technique. The measured conductivities were several orders of magnitude lower than measured previously on the single shock Hugoniot because of lower temperatures achieved under shock reverberation. Also the measured conductivities in the shock reverberation

Marina Bastea; A. C. Mitchell; W. J. Nellis

2000-01-01

145

Assembly for electrical conductivity measurements in the piston cylinder device  

SciTech Connect

An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

Watson, Heather Christine (Dublin, CA); Roberts, Jeffrey James (Livermore, CA)

2012-06-05

146

Electrical Conductance, Density, and Viscosity in Mixtures of Alkali-Metal Halides and Glycerol  

Microsoft Academic Search

This paper presents the results of density, viscosity, and electrical conductivity measurements for glycerol solutions of some alkali-metal halides at 25°C. The apparent and partial molar volumes (VF and V1) in mixtures of KCl, NaCl, KBr, KI, and glycerol were calculated from the density data. The Debye–Hückel limiting law was assumed to be valid at low concentrations, and values of

A. Hammadi

2004-01-01

147

The effect of water on the electrical conductivity of olivine.  

PubMed

It is well known that water (as a source of hydrogen) affects the physical and chemical properties of minerals--for example, plastic deformation and melting temperature--and accordingly plays an important role in the dynamics and geochemical evolution of the Earth. Estimating the water content of the Earth's mantle by direct sampling provides only a limited data set from shallow regions (<200 km depth). Geophysical observations such as electrical conductivity are considered to be sensitive to water content, but there has been no experimental study to determine the effect of water on the electrical conductivity of olivine, the most abundant mineral in the Earth's mantle. Here we report a laboratory study of the dependence of the electrical conductivity of olivine aggregates on water content at high temperature and pressure. The electrical conductivity of synthetic polycrystalline olivine was determined from a.c. impedance measurements at a pressure of 4 GPa for a temperature range of 873-1,273 K for water contents of 0.01-0.08 wt%. The results show that the electrical conductivity is strongly dependent on water content but depends only modestly on temperature. The water content dependence of conductivity is best explained by a model in which electrical conduction is due to the motion of free protons. A comparison of the laboratory data with geophysical observations suggests that the typical oceanic asthenosphere contains approximately 10(-2) wt% water, whereas the water content in the continental upper mantle is less than approximately 10(-3) wt%. PMID:17066032

Wang, Duojun; Mookherjee, Mainak; Xu, Yousheng; Karato, Shun-ichiro

2006-10-26

148

The electrical conductivity of in vivo human uterine fibroids.  

PubMed

The purpose of this study was to determine the value of electrical conductivity that can be used for numerical modelling in vivo radiofrequency ablation (RFA) treatments of human uterine fibroids. No experimental electrical conductivity data have previously been reported for human uterine fibroids. In this study electrical data (voltage) from selected in vivo clinical procedures on human uterine fibroids were used to numerically model the treatments. Measured versus calculated power dissipation profiles were compared to determine uterine fibroid electrical conductivity. Numerical simulations were conducted utilising a wide range of values for tissue thermal conductivity, heat capacity and blood perfusion coefficient. The simulations demonstrated that power dissipation was insensitive to the exact values of these parameters for the simulated geometry, treatment duration, and power level. Consequently, it was possible to determine tissue electrical conductivity without precise knowledge of the values for these parameters. Results of this study showed that an electrical conductivity for uterine fibroids of 0.305?S/m at 37°C and a temperature coefficient of 0.2%/°C can be used for modelling Radio Frequency Ablation of human uterine fibroids at a frequency of 460?kHz for temperatures from 37°C to 100°C. PMID:21501027

DeLonzor, Russ; Spero, Richard K; Williams, Joseph J

2011-01-01

149

Conductivity  

NSDL National Science Digital Library

Students make a simple conductivity tester using a battery and light bulb. They learn the difference between conductors and insulators of electrical energy as they test a variety of materials for their ability to conduct electricity.

Integrated Teaching And Learning Program

150

“SIGMELTS”: A web portal for electrical conductivity calculations in geosciences  

NASA Astrophysics Data System (ADS)

Electrical conductivity measurements in the laboratory are critical for interpreting geoelectric and magnetotelluric profiles of the Earth's crust and mantle. In order to facilitate access to the current database on electrical conductivity of geomaterials, we have developed a freely available web application (SIGMELTS) dedicated to the calculation of electrical properties. Based on a compilation of previous studies, SIGMELTS computes the electrical conductivity of silicate melts, carbonatites, minerals, fluids, and mantle materials as a function of different parameters, such as composition, temperature, pressure, water content, and oxygen fugacity. Calculations on two-phase mixtures are also implemented using existing mixing models for different geometries. An illustration of the use of SIGMELTS is provided, in which calculations are applied to the subduction zone-related volcanic zone in the Central Andes. Along with petrological considerations, field and laboratory electrical data allow discrimination between the different hypotheses regarding the formation and rise from depth of melts and fluids and quantification of their storage conditions.

Pommier, A.; Le-Trong, E.

2011-09-01

151

Electrical Conductivities of Liquid Egg Products and Fruit Juices Exposed to High Pulsed Electric Fields  

Microsoft Academic Search

Electrical conductivity can be used to monitor important changes in a food product during pulsed electric field (PEF) processing. Electrical conductivities of selected fruit juices (namely apple, orange, and pineapple juices) and liquid egg products (namely whole egg, yolk, and egg white) were determined online during a PEF treatment. The property was measured at broad processing temperatures ranging from 5

Malek Amiali; Michael O. Ngadi; Vijaya G. S. Raghavan; D. H. Nguyen

2006-01-01

152

Microstructure, electrical conductivity, and piezoelectric properties of bismuth titanate  

Microsoft Academic Search

A study was conducted on the effects of microstructure, atmosphere, and several dopants on the electrical conductivity of bismuth titanate (BiâTiâOââ, BIT). Increased grain size increased the conductivity in undoped BIT as did acceptor dopants that substituted for either Bi (Ca and Sr) or Ti(Fe). A donor dopant (Nb) decreased the conductivity in BIT by as much as 3 orders

Holly S. Shulman; Martin Testorf; Dragan Damjanovic; Nava Setter

1996-01-01

153

Electric Conductivity of Ferroelectric Pb5Ge3O11  

Microsoft Academic Search

Electric conductivity of ferroelectric Pb5Ge3O11 single crystal was measured near the Curie point, thetaf{=}177°C. An a.c. method was adopted at very low frequency range of several Hz. At the low frequency limit the conductivity represents approximately the bulk d.c. conductivity. Near and above the Curie point, the crystal is semiconductive, sigma˜10-6 Omega-1m-1. Activation energies estimated from the conductivity data taken

Yoshihiro Goto; Etsuro Sawaguchi

1979-01-01

154

Electrical conductivity of detonation-deposited hard-alloy coatings  

Microsoft Academic Search

A study was made of the electrical conductivity of WC-base detonation coatings at 20–900°C. It is demonstrated that such spray-deposited coatings have a laminar structure, which accounts for the anisotropy of their conductivity. Phase changes occurring in a coating affect mainly its conductivity measured in a direction perpendicular to the deposition axis. Data on anisotropy of conductivity can be utilized

Ts. A. Kanevskaya; S. Yu. Sharivker; A. P. Garda; E. A. Astakhov; T. G. Kutsenok

1975-01-01

155

A high accuracy technique to measure the electrical conductivity of liquids using small test samples  

SciTech Connect

A large quantity of a sample is usually required in electrical conductivity measurements of fluids. If precise electrical conductivity measurements are to be performed while using small test samples, it is necessary to study the effects of both fringe electric fields and interfacial properties. These effects were investigated here by using a novel technique termed the triangular waveform voltage method. The results using this technique revealed: (1) the fringe electric fields may be identified as an increase in apparent electrode area; and (2) the interfacial effects may be simply treated as an interfacial resistance. It was found that the increase of the electrode area due to the fringe electric fields may be reduced to below 1% at small electrode separations; the interfacial resistance is largely dependent of measurement frequency, electrode separation, and the electrical conductivity of the liquid. In general we show that the impact of interfacial resistance can be significantly reduced and the error in the electrical conductivity measurements for small liquid samples can be reduced from 40% to become less than {+-}1% in the tested NaCl(aq) solutions, spanning three decades of concentration, by adopting this new method.

Wu, Jianping; Stark, J. P. W. [Engineering Department, Queen Mary, University of London, London E1 4NS (United Kingdom)

2007-03-01

156

Improving electrical conductivity in polycarbonate nanocomposites using highly conductive PEDOT/PSS coated MWCNTs.  

PubMed

We describe a strategy to design highly electrically conductive polycarbonate nanocomposites by using multiwalled carbon nanotubes (MWCNTs) coated with a thin layer of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate), a conductive polymer. We found that this coating method improves the electrical properties of the nanocomposites in two ways. First, the coating becomes the main electrical conductive path. Second, the coating promotes the formation of a percolation network at a low filler concentration (0.3 wt %). To tailor the electrical properties of the conductive polymer coating, we used a polar solvent ethylene glycol, and we can tune the final properties of the nanocomposite by controlling the concentrations of the elementary constituents or the intrinsic properties of the conductive polymer coating. This very flexible technique allows for tailoring the properties of the final product. PMID:23758203

Zhou, Jian; Lubineau, Gilles

2013-06-25

157

Structure and electrical conductivity of ultrathin Ni-Cu films  

SciTech Connect

The structure, phase composition, morphology, and electrical conductivity of Ni-Cu alloy ultrathin films having a thickness of d = 1-10 nm and a Cu concentration of 10-95 at % have been studied. All films are shown to be fcc Ni-Cu alloys; they have an island structure with an island size of 1.5-2 nm in the as-deposited films and of about 20 nm in the films annealed to 700 K. The electrical conductivity of the films depends on their thickness and morphology. For films with d {approx} 1 nm, the electrical conductivity is thermally activated with an activation energy E{sub a} {approx} 0.086-0.095 eV. Films with d > 3 nm exhibit the metallic temperature dependence of electrical conductivity with a positive temperature coefficient of resistivity.

Loboda, V. B., E-mail: loboda@sspu.sumy.ua; Khursenko, S. N. [Sumy State Pedagogical University (Ukraine)

2006-11-15

158

Electrical conductivity of rocks in the heating and cooling cycle  

Microsoft Academic Search

Summary The values of the electrical conductivity, recorded during the heating and cooling cycle, of eclogites and basalts are compared. The observed difference in the values is explained by reversible and irreversible changes which take place in the samples.

Marcela Lastovicková; F. Janák

1978-01-01

159

Measurement of electrical conductivity for a biomass fire.  

PubMed

A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The burner was equipped with thermocouples to measure fuel surface temperature and used as a cavity for microwaves with a laboratory quality 2-port vector network analyzer to determine electrical conductivity from S-parameters. Electrical conductivity for vegetation material flames is important for numerical prediction of flashover in high voltage power transmission faults research. Vegetation fires that burn under high voltage transmission lines reduce flashover voltage by increasing air electrical conductivity and temperature. Analyzer determined electrical conductivity ranged from 0.0058 - 0.0079 mho/m for a fire with a maximum temperature of 1240 K. PMID:19325812

Mphale, Kgakgamatso; Heron, Mal

2008-08-13

160

Measurement of Electrical Conductivity for a Biomass Fire  

PubMed Central

A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The burner was equipped with thermocouples to measure fuel surface temperature and used as a cavity for microwaves with a laboratory quality 2-port vector network analyzer to determine electrical conductivity from S-parameters. Electrical conductivity for vegetation material flames is important for numerical prediction of flashover in high voltage power transmission faults research. Vegetation fires that burn under high voltage transmission lines reduce flashover voltage by increasing air electrical conductivity and temperature. Analyzer determined electrical conductivity ranged from 0.0058 - 0.0079 mho/m for a fire with a maximum temperature of 1240 K.

Mphale, Kgakgamatso; Heron, Mal

2008-01-01

161

Electrically Conductive Polycrystalline Diamond and Particulate Metal Based Electrodes.  

National Technical Information Service (NTIS)

An electrically conducting and dimensionally stable diamond (12, 14) and metal particle (13) electrode produced by electrodepositing the metal on the diamond is described. The electrode is particularly useful in harsh chemical environments and at high cur...

G. M. Swain J. Wang

2005-01-01

162

Ion and Temperature Dependence of Electrical Conductance for Natural Waters.  

National Technical Information Service (NTIS)

Four empirical equations describing the temperature dependence of electrical conductance of aqueous solutions are compared for the case of single electrolytes. The best method uses a modified Walden product where the log of the ratio between the conductan...

J. A. Sorensen G. E. Glass

1987-01-01

163

Electrical conductivity of nanocrystalline ceria and zirconia thin films  

Microsoft Academic Search

The results of studies of the preparation, structure and electrical conductivity of ZrO2:16% Y and CeO2 thin films are presented. Dense films with grain size controlled in the region of 1–400 nm have been obtained on monocrystalline sapphire and polycrystalline Al2O3 substrates using a polymeric precursor spin coating method. The electrical conductivity of nanocrystalline thin films has been studied as

Igor Kosacki; Toshio Suzuki; Vladimir Petrovsky; Harlan U Anderson

2000-01-01

164

Electric conductance of DNA molecules with adjustable number itinerant electrons  

NASA Astrophysics Data System (ADS)

Electric transport of DNA is closely related to the itinerant ?-electrons due to the soft characteristic of DNA molecules. We suggest a model with adjustable number itinerant electrons (ANIE). The density of states (DOS), the transmission coefficient and the electric conductance were studied. It was found that the conductance depends sensitively upon the number of the itinerant electrons. Resistivity of Poly(dG)-Poly(dC) was obtained, which is well consistent with the experimental data.

Gao, Xu-Tuan; Fu, Xue; Liu, De-Sheng; Xie, Shi-Jie

2006-01-01

165

Influential factors on deicing performance of electrically conductive concrete pavement  

Microsoft Academic Search

The deicing experiment of carbon fiber reinforced electrically conductive concrete (CFRC) slab was conducted in laboratory\\u000a at first, then the deicing process of CFRC pavement was analyzed by means of finite element method (FEM). At last, based on\\u000a the energy conservation law and the computing results of finite element method, the influential factors including the setting\\u000a of electric heating layer,

Tang Zuquan; Qian Jueshi; Li Zhuoqiu; Wu Chuanming

2006-01-01

166

Electrical conductivity of the burning surface of ammonium perchlorate  

SciTech Connect

The authors perform experimental measurements of the electrical conductivity of the surface of ammonium perchlorate during its combustion in order to gain insight into its combustion kinetics. Samples with additions of 5% copper salicylate and sodium salicylate were also investigated. Both additives were found to substantially increase the combustion rate. Electrical conductivity was found to depend heavily on temperature and pressure. Ionized combustion products are also analyzed. A full description of the experimental method and instrumentation is given.

Ivashchenko, Yu.S.; Sadyrin, A.L.; Pavlenko, V.L.

1987-01-01

167

Electrical stunning of fish: the relationship between the electric field strength and water conductivity  

Microsoft Academic Search

The electric field in water required to stun trout is investigated experimentally. The results show how the electric field depends on water conductivity. The electric fields in water required to generate permanent insensibility in trout following exposure durations of 15, 30 and 60 s are identified. A mathematical model of the electric field in the stunning tank is constructed and

Jeff Lines; Steve Kestin

2004-01-01

168

Electrical-Impedance Tomography for Opaque Multiphase Flows in Metallic (Electrically-Conducting) Vessels.  

National Technical Information Service (NTIS)

A novel electrical-impedance tomography (EIT) diagnostic system, including hardware and software, has been developed and used to quantitatively measure material distributions in multiphase flows within electrically-conducting (i.e., industrially relevant ...

S. G. Liter J. R. Torczynski K. A. Shollenberger S. L. Ceccio

2002-01-01

169

Electrical conductivity measurement of iron at high static pressure  

NASA Astrophysics Data System (ADS)

The knowledge of the thermal conductivity of the core constrains the heat flow and the amount of radiogenic elements in the core [1]. The electrical conductivity of iron has been measured by shock compression experiments. The thermal conductivity can be then calculated using the Wiedemann-Franz law. Stacey and Loper [2] estimated the thermal conductivity of outer core liquid and suggested the absence of radiogenic heat source. However, no conductivity measurement has been carried out under core pressures by static experiments. In this study, we have conducted the electrical conductivity measurements of pure iron under high static pressure at room temperature in a diamond-anvil cell. The sample resistance was obtained by the four-terminal method. The results demonstrated that the conductivity increased with increasing pressure and dropped at ~15 GPa across phase transition from bcc to hcp structure. It then increased again with pressure up to 65 GPa. The electrical conductivity was determined to be about 1E7 S/m at 65 GPa. We estimated the electrical conductivity of iron under the CMB pressure and temperature condition to be ~ 1E6 S/m, which is comparable to the previous estimate by Stacey and Anderson [3]. The details of the experiments will be reported at the presentation. [1] Stevenson, D.J., 2003. Planetary magnetic fields. Earth Plan. Sci. Lett. 208, 1-11. [2] Stacey, F.D., Loper, D.E., 2007. Physics of the Earth Plan. Int. 161, 13-18. [3] Stacey, F.D., Anderson, O.L., 2001. Electrical and thermal conductivities of Fe-Ni-Si alloy under core conditions. Phys. Earth Planet. Inter. 124, 153-162.

Gomi, H.; Ohta, K.; Hirose, K.

2010-12-01

170

Predicting plot-scale water infiltration using the correlation between soil apparent electrical resistivity and various soil properties  

NASA Astrophysics Data System (ADS)

The identification of runoff source areas is essential for Integrated Water and Resources Management (IWRM). Although direct methods for the determination of steady-state water infiltration in soils (Inf) do exist, these are tedious and time-consuming. Geophysical techniques offer an alternative, however, geophysical data are often misinterpreted, especially in terms of the inter-relationships between soil apparent electrical resistivity (Rho) and Inf and several other soil physical or chemical properties. This paper evaluates the magnitude of the extend Rho measurements might allow prediction of Inf. This study was conducted in the Kwazulu-Natal province of South Africa where surface runoff arising from the steep slopes has a large impact in land degradation. Measurements of Rho with an RM-15 resistance meter were taken within a 10 × 30 m plot showing similar sandy-loam Acrisols but different proportions of soil surface coverage by plants (from 0-5% to 75-100%), depth to the clayey Bw horizon (D2B), top-soil (0-0.1 m) water content (?) and bulk density (BD). There was a low correlation between Rho and Inf obtained under controlled conditions of rainfall (30 mm h-1during 45 min) at fifteen 1 m2 micro-plots (r2 = 0.30). However, the correlation with the normalized Rho (Rhon) as if D2B, ?, and BD were constant over the study plot and equal to their average value, was much higher (r2 = 0.66), pointing out the need to consider the complex and multiple correlations between soil properties and Rho in an attempt to map the spatial variations of Inf. Finally, the use of Rhon as a co-kriging co-variate appeared to significantly improve the short range spatial prediction of water infiltration in soils and thus IWRM implementation.

Chaplot, Vincent; Jewitt, Graham; Lorentz, Simon

171

Evolving concepts on the electrical conductivity of the continental crust  

Microsoft Academic Search

Several decades of geophysical research have established that the middle and lower crust are typically much more electrically conductive than the upper crust and orders of magnitude more so than either dry crystalline rocks or rock-forming silicate minerals at similar conditions. The high conductivities at depth were originally ascribed to the presence of saline fluids. Two problems with this view

E. A. Mathez

2002-01-01

172

ION AND TEMPERATURE DEPENDENCE OF ELECTRICAL CONDUCTANCE FOR NATURAL WATERS  

EPA Science Inventory

Four empirical equations describing the temperature dependence of electrical conductance of aqueous solutions are compared for the case of single electrolytes. The best method uses a modified Walden product where the log of the ratio between the conductances at two temperatures i...

173

Electrical conductivity: a useful technique in teaching geomorphology  

Microsoft Academic Search

The electrical conductivity of a water sample is proportional to its total dissolved solids content. Since conductivity can be measured easily and quickly by commercially available meters it is admirably suited to geomorphological field work on the dissolved solids content of natural waters. The technique lends itself to exercises involving work in the field, the classroom and the laboratory and

Brian Finlayson

1979-01-01

174

Electrical and mechanical characterization of carbon nanotube filled conductive adhesive  

Microsoft Academic Search

Electronic assemblies rely heavily on soldering to attach components to the interconnect wiring on printed circuit boards and other types of substrates. In response to environmental legislation, the lead-tin alloys commonly used for soldering are being replaced with lead-free alloys and electrically conductive adhesives. Isotropic conductive adhesives (ICA) filled with metal particles are an alternative to solder reflow processing. ICA

Jing Li; Janet K. Lumpp

2006-01-01

175

Distinguishability of Conductivities by Electric Current Computed Tomography  

Microsoft Academic Search

We give criteria for the distinguishability of two different conductivity distributions inside a body by electric current computed tomography (ECCT) systems with a specified precision. It is shown in a special case how these criteria can be used to determine the measurement precision needed to distinguish between two different conductivity distributions. It is also shown how to select the patterns

David Isaacson

1986-01-01

176

Density, speed of sound, and electrical conductance of ionic liquid 1-hexyl-3-methyl-imidazolium bromide in water at different temperatures  

Microsoft Academic Search

Densities, speeds of sound, and electrical conductances in the aqueous solutions of room temperature ionic liquid, 1-hexyl-3-methyl-imidazolium bromide, [HMIm]Br were measured at temperatures T=(283.15 to 308.15)K and atmospheric pressure. Apparent molar volumes V?, isentropic compressibilities ?S, apparent molar isentropic compressibilities ??, and molar conductivities ? were determined. The corresponding limiting apparent molar quantities were found by extrapolation to infinite dilution

Hemayat Shekaari; Yagoub Mansoori; Rahmat Sadeghi

2008-01-01

177

Electric field enhanced conductivity in strongly coupled dense metal plasma  

SciTech Connect

Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field ({approx}6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

Stephens, J.; Neuber, A. [Center for Pulsed Power and Power Electronics, Texas Tech University, Lubbock, Texas 79409 (United States)

2012-06-15

178

Lorentz force sigmometry: A contactless method for electrical conductivity measurements  

NASA Astrophysics Data System (ADS)

The present communication reports a new technique for the contactless measurement of the specific electrical conductivity of a solid body or an electrically conducting fluid. We term the technique ``Lorentz force sigmometry'' where the neologism ``sigmometry'' is derived from the Greek letter sigma, often used to denote the electrical conductivity. Lorentz force sigmometry (LoFoS) is based on similar principles as the traditional eddy current testing but allows a larger penetration depth and is less sensitive to variations in the distance between the sensor and the sample. We formulate the theory of LoFoS and compute the calibration function which is necessary for determining the unknown electrical conductivity from measurements of the Lorentz force. We conduct a series of experiments which demonstrate that the measured Lorentz forces are in excellent agreement with the numerical predictions. Applying this technique to an aluminum sample with a known electrical conductivity of ?Al=20.4MS/m and to a copper sample with ?Cu=57.92MS/m we obtain ?Al=21.59MS/m and ?Cu=60.08MS/m, respectively. This demonstrates that LoFoS is a convenient and accurate technique that may find application in process control and thermo-physical property measurements for solid and liquid conductors.

Uhlig, Robert P.; Zec, Mladen; Ziolkowski, Marek; Brauer, Hartmut; Thess, André

2012-05-01

179

UV-induced surface electrical conductivity jump of polymer nanocomposites  

SciTech Connect

A method of improving the electrical conductivity of polymer nanocomposites under UV irradiation was described. An anatase TiO{sub 2}-grafted carbon nanotube could function as a conductive filler and a photocatalyst when it compounds with a poly(L-lactide) to produce a composite. After UV irradiation, the decomposition of the polymer only occurred on the surface of a poly(L-lactide)/TiO{sub 2} grafted carbon nanotube composite and not on bulk, resulting in an electrical conductivity jump as high as six orders of magnitude.

Chen Guangxin [College of Materials Science and Engineering, Beijing University of Chemical Technology, P.O. Box 206, Beijing 100029 (China); Miyauchi, Masahiro; Shimizu, Hiroshi [Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

2008-05-19

180

Electric conduction mechanism in conjugated polymers studied using flicker noise spectroscopy  

NASA Astrophysics Data System (ADS)

Spectroscopy of Stochastic Signals (3S) has been used to study conduction behavior in electrochemically deposited conductive polymers (CP) using as example polyaniline and poly(3-methyl thiophene). Within the 3S approach, the conduction process is considered as a stochastic process in heterogeneous disordered system rather than as some classical conduction mechanisms like Schottky or Poole-Frenkel emission. We have been able to distinguish several modes of the conduction process in conducting polymers using the 3S methodology. Particularly, we have established that the transport of charge carriers in highly doped CPs is much less correlated than in non-doped ones, that is, at low doping levels elementary processes involved in the conduction are more correlated than in highly doped polymer. By increasing applied electric field we also achieve lower correlation in a sequence of elementary events contributing to the conductivity of CP. Apparently, the change in the correlation length corresponds to changing mechanism of the electrical conduction. The lower correlation in highly doped sample can be attributed to various factors including change in CP conformation, enhancement in inter-chain charge transfer and generation of polaron lattice. The obtained results show the high informative potential of the 3S method in studying conduction mechanism in conducting polymers.

Parkhutik, Vitali P.; Patil, Rahul; Harima, Yutaka

2003-05-01

181

High temperature electrical conductivity of rigid polyurethane foam  

NASA Astrophysics Data System (ADS)

The temperature dependence of the electrical conductivity of three rigid polyurethane foams prepared using different formulations was measured to approx. 320 C. The materials exhibit similar conductivity characteristics, showing a pronounced increase in conductivity with increasing temperature. The insulating characteristics to approx. 200 C are better than that for phenolic materials (glass fabric reinforced), and are similar to those for silicone materials (glass microsphere reinforced). At higher temperatures (500 to 600 C), the phenolics and silicones are better insulators.

Johnson, R. T., Jr.

1984-03-01

182

Variations in electrical conductivity of rocks above metamorphic conditions  

Microsoft Academic Search

This study of the electrical conductivity of metamorphic rocks as a function of temperature highlights the importance of conductivity variations associated with dehydration. We observed conductivity changes for anhydrous rocks and hydrous amphibolites up to 1100K at 0.5GPa. Our experimental results revealed that dehydration takes place and that there is a non-linear variation above metamorphic temperatures. To evaluate the observed

Kiyoshi Fuji-ta; Tomoo Katsura; Masahiro Ichiki; Takuya Matsuzaki; Tomoyuki Kobayashi

2011-01-01

183

The role of acids in electrical conduction through ice  

NASA Astrophysics Data System (ADS)

Electrical conduction through meteoric polar ice is controlled by soluble impurities that originate mostly from sea salt, biomass burning, and volcanic eruptions. The strongest conductivity response is to acids, yet the mechanism causing this response has been unclear. Here we elucidate conduction mechanisms in ice using broadband dielectric spectroscopy of meteoric polar ice cores. We find that conduction through polycrystalline polar ice is consistent with Jaccard theory for migration of charged protonic point defects through single ice crystals, except that bulk DC conduction is impeded by grain boundaries. Neither our observations nor modeling using Archie's Law support the hypothesis that grain-boundary networks of unfrozen acids cause significant electrolytic conduction. Common electrical logs of ice cores (by electrical conductivity measurement [ECM] or dielectric profiling [DEP]) and the attenuation of radio waves in ice sheets thus respond to protonic point defects only. This response implies that joint interpretation of electrical and chemical logs can determine impurity partitioning between the lattice and grain boundaries or inclusions. For example, in the Greenland Ice Core Project (GRIP) ice core from central Greenland, on average more than half of the available lattice-soluble impurities (H+, Cl-, NH4+) create defects. Understanding this partitioning could help further resolve the nature of past changes in atmospheric chemistry.

Stillman, David E.; MacGregor, Joseph A.; Grimm, Robert E.

2013-03-01

184

Effects of contact resistance on electrical conductivity measurements of SiC-based materials  

NASA Astrophysics Data System (ADS)

A combination 2/4-probe method was used to measure electrical resistances across a pure, monolithic CVD-SiC disc sample with contact resistance at the SiC/metallic electrode interfaces. By comparison of the almost simultaneous 2/4-probe measurements, the specific contact resistance (Rc) and its temperature dependence were determined for two types (sputtered gold and porous nickel) electrodes from room temperature (RT) to ˜973 K. The Rc-values behaved similarly for each type of metallic electrode: Rc > ˜1000 ? cm2 at RT, decreasing continuously to ˜1-10 ? cm2 at 973 K. The temperature dependence of the inverse Rc indicated thermally activated electrical conduction across the SiC/metallic interface with an apparent activation energy of ˜0.3 eV. For the flow channel insert application in a fusion reactor blanket, contact resistance potentially could reduce the transverse electrical conductivity by about 50%.

Youngblood, G. E.; Thomsen, E. C.; Henager, C. H.

2013-11-01

185

The electrical conduction variation in stained carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes become stained from coupling with foreign molecules, especially from adsorbing gas molecules. The charge exchange, which is due to the orbital hybridization, occurred in the stained carbon nanotube induces electrical dipoles that consequently vary the electrical conduction of the nanotube. We propose a microscopic model to evaluate the electrical current variation produced by the induced electrical dipoles in a stained zigzag carbon nanotube. It is found that stronger orbital hybridization strengths and larger orbital energy differences between the carbon nanotube and the gas molecules help increasing the induced electrical dipole moment. Compared with the stain-free carbon nanotube, the induced electrical dipoles suppress the current in the nanotube. In the carbon nanotubes with induced dipoles the current increases as a result of increasing orbital energy dispersion via stronger hybridization couplings. In particular, at a fixed hybridization coupling, the current increases with the bond length for the donor-carbon nanotube but reversely for the acceptor-carbon nanotube.

Sun, Shih-Jye; Wei Fan, Jun; Lin, Chung-Yi

2012-01-01

186

Spatial interpolation of soil organic carbon using apparent electrical conductivity as secondary information  

Microsoft Academic Search

Soil organic carbon (SOC) spatial characterization is necessary to evaluate under what circumstances soil acts as a source or sink of carbon dioxide. However, at the field or catchment scale it is hard to accurately characterize its spatial distribution since large numbers of soil samples are necessary. As an alternative, near-surface geophysical sensor-based information can improve the spatial estimation of

G. Martinez; K. Vanderlinden; R. Ordóñez; J. L. Muriel

2009-01-01

187

SOYBEAN ROOT DISTRIBUTION RELATED TO CLAYPAN SOIL PROPERTIES AND APPARENT SOIL ELECTRICAL CONDUCTIVITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soybean [Glycine max (L.)] yield in claypan soils varies as a result of systematic relationships with soil properties and landscape position. This variability is likely caused by soil-landscape interactions with soybean roots. While much data exists on the landscape variability of yield, field obser...

188

ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Apparently Negative Electric Polarization in Shaped Graded Dielectric Materials  

NASA Astrophysics Data System (ADS)

By using a first-principles approach, we investigate the pathway of electric displacement fields in shaped graded dielectric materials existing in the form of cloaks with various shapes. We reveal a type of apparently negative electric polarization (ANEP), which is due to a symmetric oscillation of the paired electric permittivities, satisfying a sum rule. The ANEP does not occur for a spherical cloak, but appears up to maximum as a/b (the ratio between the long and short principal axis of the spheroidal cloak) is about 5/2, and eventually disappears as a/b becomes large enough corresponding to a rod-like shape. Further, the cloaking efficiency is calculated for different geometrical shapes and demonstrated to closely relate to the ANEP. The possibility of experiments is discussed. This work has relevance to dielectric shielding based on shaped graded dielectric materials.

Fan, Chun-Zhen; Gao, Yin-Hao; Gao, Yong; Huang, Ji-Ping

2010-05-01

189

Electrical conductivity of chromate conversion coating on electrodeposited zinc  

NASA Astrophysics Data System (ADS)

For certain applications of galvanized steel protected with conversion coatings it is important that the surface is electrically conductive. This is especially important with mating surfaces for electromagnetic compatibility. This paper addresses electrical conductivity of chromate conversion coatings. A cross-matrix study using different zinc plating techniques by different labs showed that the main deciding factor is the type of zinc-plating bath used rather than the subsequent chromating process. Thus, chromated zinc plate electrodeposited from cyanide baths is non-conductive while that from alkaline (non-cyanide) and acid baths is conductive, even though the plate from all the bath types is conductive before conversion coating. The results correlate well with the microscopic structure of the surfaces as observed with scanning electron microscopy (SEM) and could be further corroborated and rationalized using EDX and Auger spectroscopies.

Tencer, Michal

2006-09-01

190

Microwave measurement of the electrical conductivity of an elementary grain of a conducting powder  

NASA Astrophysics Data System (ADS)

Radar-absorbing materials can be obtained by combining a conducting powder with a dielectric matrix. The microwave electrical conductivity of an elementary grain of the powder is a key parameter for modeling such composites. In this paper, a calculation is made of the effective complex magnetic permeability of a dielectric/conducting powder composite as a function of the composition and the elementary-grain conductivity. Then an open-cavity method for measuring the complex magnetic permeability is presented. The results obtained make it possible to directly relate the cavity-resonance characteristics to the elementary-grain conductivity.

Guillot, T.; Bobillot, G.

191

Multi-rate flowing Wellbore electric conductivity logging method  

SciTech Connect

The flowing wellbore electric conductivity logging method involves the replacement of wellbore water by de-ionized or constant-salinity water, followed by constant pumping with rate Q, during which a series of fluid electric conductivity logs are taken. The logs can be analyzed to identify depth locations of inflow, and evaluate the transmissivity and electric conductivity (salinity) of the fluid at each inflow point. The present paper proposes the use of the method with two or more pumping rates. In particular it is recommended that the method be applied three times with pumping rates Q, Q /2, and 2Q. Then a combined analysis of the multi-rate data allows an efficient means of determining transmissivity and salinity values of all inflow points along a well with a confidence measure, as well as their inherent or far-field pressure heads. The method is illustrated by a practical example.

Tsang, Chin-Fu; Doughty, Christine

2003-04-22

192

Electrical conductivity of rigid polyurethane foam at high temperature  

NASA Astrophysics Data System (ADS)

The electrical conductivity of rigid polyurethane foam, used for electronic encapsulation, was measured during thermal decomposition to 3400 C. At higher temperatures the conductance continues to increase. With pressure loaded electrical leads, sample softening results in eventual contact between electrodes which produces electrical shorting. Air and nitrogen environments show no significant dependence of the conductivity on the atmosphere over the temperature range. The insulating characteristics of polyurethane foam below approx. 2700 C are similar to those for silicone based materials used for electronic case housings and are better than those for phenolics. At higher temperatures (greater than or equal to 2700 C) the phenolics appear to be better insulators to approx. 5000 C and the silicones to approx. 6000 C. It is concluded that the Sylgard 184/GMB encapsulant is a significantly better insulator at high temperature than the rigid polyurethane foam.

Johnson, R. T., Jr.

1982-08-01

193

Effect of humidity on electrical conductivity of zinc stearate nanofilms  

Microsoft Academic Search

In this work, stearic acid (StAc) and zinc stearate (ZnSt2) nanofilms were deposited on glass and silver substrates using Langmuir–Blodgett (LB) film technique and their structural and electrical properties were investigated. X-ray diffraction and IR techniques revealed that more crystalline and better films were obtained from ZnSt2 compare to StAc. Electrical conductivity of ZnSt2 LB films with 13 layers having

Serdar Ozturk; Devrim Balkose; Salih Okur; Junzo Umemura

2007-01-01

194

THE SENSING OF ELECTRICAL CAPACITANCES BY WEAKLY ELECTRIC MORMYRID FISH: EFFECTS OF WATER CONDUCTIVITY  

Microsoft Academic Search

Summary Weakly electric fish can perceive electric properties of objects by monitoring the responses of their epidermal electroreceptors (mormyromasts) to their own electric organ discharges (EOD), a process known as active electrolocation. Mormyrid fish can distinguish capacitative from resistive properties of objects. It is mainly animate objects that possess capacitative properties. Water conductivity is a critical environmental factor that varies

GERHARD VON DER EMDE

1993-01-01

195

Electrical and thermal conductivity of hybrid nanocomposites with giant strain  

NASA Astrophysics Data System (ADS)

The prospect of electronic circuits that are stretchable and bendable promises tantalizing applications such as skin-like electronics, conformable sensors, and lightweight solar cells. The optimization of electronic, thermal, and mechanical properties of conductive and extensible materials is necessary for the application of energy device. Here we demonstrate the theoretical prediction for the electrical conductivity of the nanocomposites compared with experimental results. Also, we present the giant dependence of electrical conductivity on strain and the large positive thermal expansion that can be expected for the elastomer matrix. The percolation threshold (26 vol% of Ag, average interparticle distance model) and Poisson's ratio (Vt=0.33, Vw=0.2) of nanocomposites are significant factors that can determine the electrical and thermal conductivity with giant strain. The thermal conductivity for the electronically conducting elastomeric film is relatively high at the zero-strain state, and shows a non-metallic temperature dependence consistent with phonon transport. The observed combinational property of a very small dependence of conductivity on temperature with an exponential dependence can be suitable for for the mechanical strain sensing.

Chun, Kyoung-Yong; Kim, Shi Hyeong; Shin, Min Kyoon; Spinks, Geoffrey M.; Aliev, Ali E.; Baughman, Ray H.; Kim, Seon Jeong

2013-04-01

196

Corrosion-protective coatings from electrically conducting polymers  

SciTech Connect

In a joint research effort involving the Kennedy Space Center and the Los Alamos National Laboratory, electrically conductive polymer coatings have been developed as corrosion-protective coatings for metal surfaces. At the Kennedy Space Center, the launch environment consists of marine, severe solar, and intermittent high acid/elevated temperature conditions. Electrically conductive polymer coatings have been developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

Thompson, K.G.; Bryan, C.J. [National Aeronautics and Space Administration, Cocoa Beach, FL (United States). John F. Kennedy Space Center; Benicewicz, B.C.; Wrobleski, D.A. [Los Alamos National Lab., NM (United States)

1991-12-31

197

Corrosion-protective coatings from electrically conducting polymers  

SciTech Connect

In a joint research effort involving the Kennedy Space Center and the Los Alamos National Laboratory, electrically conductive polymer coatings have been developed as corrosion-protective coatings for metal surfaces. At the Kennedy Space Center, the launch environment consists of marine, severe solar, and intermittent high acid/elevated temperature conditions. Electrically conductive polymer coatings have been developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

Thompson, K.G.; Bryan, C.J. (National Aeronautics and Space Administration, Cocoa Beach, FL (United States). John F. Kennedy Space Center); Benicewicz, B.C.; Wrobleski, D.A. (Los Alamos National Lab., NM (United States))

1991-01-01

198

Instrumentation development for electrical conductivity imaging in polycrystalline diamond cutters  

NASA Astrophysics Data System (ADS)

We previously reported on an electrical conductivity non-destructive inspection methodology for polycrystalline diamond cutters. These cylindrical cutters for oil and gas drilling feature a thick polycrystalline diamond layer on a tungsten carbide substrate. We use electrical impedance tomography to image the conductivity in the diamond table. In this paper we report on progress in preparing this instrument for factory deployment. Instrument enhancements include an adjustable part holder, a field-swappable sensor and GPU-enabled software capable of rapidly acquiring images.

Bogdanov, G.; Wiggins, J.; Rhodes, J.; Bertagnolli, K.; Ludwig, R.

2013-01-01

199

Electrically conductive doped block copolymer of polyacetylene and polyisoprene  

DOEpatents

An electrically conductive block copolymer of polyisoprene and polyacetyl and a method of making the same are disclosed. The polymer is prepared by first polymerizing isoprene with n-butyllithium in a toluene solution to form an active isoprenyllithium polymer. The active polymer is reacted with an equimolar amount of titanium butoxide and subsequently exposed to gaseous acetylene. A block copolymer of polyisoprene and polyacetylene is formed. The copolymer is soluble in common solvents and may be doped with I.sub.2 to give it an electrical conductivity in the metallic regime.

Aldissi, Mahmoud (Los Alamos, NM)

1985-01-01

200

Contamination from electrically conductive silicone tubing during aerosol chemical analysis  

SciTech Connect

Electrically conductive silicone tubing is used to minimize losses in sampling lines during the analysis of airborne particle size distributions and number concentrations. We report contamination from this tubing using gas chromatography-mass spectrometry (GC-MS) of filter-collected samples as well as by particle mass spectrometry. Comparison of electrically conductive silicone and stainless steel tubing showed elevated siloxanes only for the silicone tubing. The extent of contamination increased with length of tubing to which the sample was exposed, and decreased with increasing relative humidity.

Yu, Yong; Alexander, M. L.; Perraud, Veronique; Bruns, Emily; Johnson, Stan; Ezell, Michael J.; Finlayson-Pitts, Barbara J.

2009-06-01

201

Electrical conductivity of niobium-containing oxide-fluoride melts  

Microsoft Academic Search

The effect of Nb2O5 on electrical conductivity of metals based on CaF2 and CaF2-30% Al2O3 at T = 1500–1900 K in an oxidizing atmosphere is investigated using an ac bridge at the frequency 5 kHz. It is found that, as\\u000a the Nb2O5 concentration increases from 0 to 25%, the electrical conductivity of the melts decreases, while the activation energy of

S. A. Istomin; S. A. Krasikov; E. A. Pastukhov; V. V. Ryabov

2007-01-01

202

Electrical Conductivity at the Core of a Magnetar  

NASA Astrophysics Data System (ADS)

An expression for the electrical conductivity at the core of a magnetar is derived using Boltzmann kinetic equation with the relaxation time approximation. The rates for the relevant scattering processes, e.g., electron-electron and electron-proton scattering processes are evaluated in presence of strong quantizing magnetic fields using tree level diagrams. It is found that in the presence of a strong quantizing magnetic field, electrical conductivity behaves like a second rank tensor. However, if the zeroth Landau levels are only level occupied by the charged particles, it again behaves like a scalar of a one-dimensional system.

Ghosh, Sutapa; Goswami, Kanupriya; Chakrabarty, Somenath; Goyal, Ashok; Ghosh, Sanchayita; Ruffini, R.

203

Electrical conduction in 7 nm wires constructed on ?-DNA  

NASA Astrophysics Data System (ADS)

We examine the morphological and electrical characteristics of nanowires fabricated on DNA templates via palladium (Pd) reduction. ?-DNA molecules were stretched and aligned on a mica surface using a molecular combing technique, followed by an electroless deposition of palladium, resulting in formation of nanowires with nominal width of 7 nm. We investigated the size distribution of nanowires with atomic force microscopy and made electrical connections to the wires by metal evaporation through multiple shadow masks. Electrical characterization of the nanowires under various bias conditions, variable temperature, and with different contact metal work functions revealed a conduction mechanism resembling that of granular metals.

Lund, John; Dong, Jianchun; Deng, Zhaoxiang; Mao, Chengde; Parviz, Babak A.

2006-06-01

204

Carbonatite melts and electrical conductivity in the asthenosphere.  

PubMed

Electrically conductive regions in Earth's mantle have been interpreted to reflect the presence of either silicate melt or water dissolved in olivine. On the basis of laboratory measurements, we show that molten carbonates have electrical conductivities that are three orders of magnitude higher than those of molten silicate and five orders of magnitude higher than those of hydrated olivine. High conductivities in the asthenosphere probably indicate the presence of small amounts of carbonate melt in peridotite and can therefore be interpreted in terms of carbon concentration in the upper mantle. We show that the conductivity of the oceanic asthenosphere can be explained by 0.1 volume percent of carbonatite melts on average, which agrees with the carbon dioxide content of mid-ocean ridge basalts. PMID:19039132

Gaillard, Fabrice; Malki, Mohammed; Iacono-Marziano, Giada; Pichavant, Michel; Scaillet, Bruno

2008-11-28

205

Experiment of electrical conductivity at low temperature (preliminary measurement)  

SciTech Connect

A muon collider needs very large amount of RF power, how to reduce the RF power consumption is of major concern. Thus the application of liquid nitrogen cooling has been proposed. However, it is known that the electrical conductivity depends on many factors and the data from different sources vary in a wide range, especially the data of conductivity of beryllium has no demonstration in a real application. Therefore it is important to know the conductivity of materials, which are commercially available, and at a specified frequency. Here, the results of the preliminary measurement on the electrical conductivity of copper at liquid nitrogen temperature are summarized. Addressed also are the data fitting method and the linear expansion of copper.

Zhao, Y.; Wang, H.

1998-07-01

206

The Electrical Conductivity and Thermoelectric Power of Bismuth Telluride  

Microsoft Academic Search

The electrical conductivity and thermoelectric power of the semiconductor Bi2Te3 have been measured between 150°K and 300°K. n-type and p-type samples with a wide range of carrier concentration have been included. Most samples have shown extrinsic conduction and have been partially degenerate over at least part of the temperature range, so it has been necessary to use Fermi-Dirac statistics in

H J Goldsmid

1958-01-01

207

Electrical conductivities of multi-wall carbon nano tubes  

Microsoft Academic Search

Electrical conductivities of individual multi-wall carbon nano tubes have been measured using a micro manipulator by two probe method. The nano tubes are 15~50 nm in diameter and longer than 20 ?m in length. The resistance of tubes is several k? per ?m, which gives the average conductivity as 1,000~2,000 S\\/cm. The current-voltage characteristics at high field are also studied

K. Kaneto; M. Tsuruta; G. Sakai; W. Y. Cho; Y. Ando

1999-01-01

208

The Electrical Conductivity of Strontium-Barium Niobate  

NASA Astrophysics Data System (ADS)

We propose an explanation for the high electrical conductivity of the ferroelectric strontium-barium niobate. As the temperature T approaches the ferroelectric transition T c, the static dielectric constant \\varepsilon(0) diverges when a soft mode occurs. This divergence of \\varepsilon(0) reduces the donor binding energy, and increases the effective Bohr radius of the donor. The electrons bound to the donors become unbound, and the material becomes conductive.

Mahan, G. D.; Sofo, J. O.

2013-07-01

209

Electrical Conductivity of Thick Films Made from Silver Methylcarbamate Paste  

NASA Astrophysics Data System (ADS)

We have explored the electrical conductivity of thick films made from silver methylcarbamate paste using metallic silver as the electrically conductive phase. The paste was composed of 30 wt.% to 90 wt.% organic vehicle and 10 wt.% to 70 wt.% functional phase precursor (silver methylcarbamate). After the paste was sintered, films with thickness of 4.50 ?m to 12.70 ?m were obtained, in which the elemental percentage of silver varied from about 5 wt.% to above 99 wt.%. Experiments showed that both the electrical conductivity and the elemental percentage were mainly affected by the initial silver content in the paste and the parameters of the sintering process. For given sintering conditions, higher initial silver content led to higher elemental percentage of silver, improving the electrical conductivity of the thick film. The conditions of the sintering process had a significant influence on the evaporation and decomposition rates of the paste components, the elemental percentage of silver, and the microstructure of the thick film. Higher temperatures, longer times, lower heating rates, and more oxygen-rich sintering atmospheres were found to accelerate the evaporation and decomposition and increase the elemental percentage of silver, both of which served to enhance the electrical conductivity. For initial silver contents less than about 10 wt.%, the lowest electrical resistivity of the thick film only reached the order of 10-4 ? cm, irrespective of the sintering conditions. For contents between 10 wt.% and 25 wt.%, it was possible to attain lowest resistivity values on the order of 10-5 ? cm. Above 25 wt.%, the lowest resistivity could reach 10-6 ? cm, comparable to that of bulk silver.

Liu, Jianguo; Jiang, Min; Zeng, Xiaoyan

2013-10-01

210

Electrical conductivity of olivine, a dunite, and the mantle  

SciTech Connect

Laboratory studies of the electrical conductivity of rocks and minerals are vital to the interpretation of electromagnetic soundings of the Earth's mantle. To date, the most reliable data have been collected from single crystals. The authors have extended these studies with electrical conductivity measurements on a dunite from North Carolina, in the temperature range of 600-1,200 C and under controlled oxygen fugacity. Observations of conductivity as a function of oxygen fugacity and temperature demonstrate that conduction in the dunite is indistinguishable from conduction in single olivine crystals. Thus the common practice of exaggerating the single-crystal conductivities to account for conduction by grain boundary phases in the mantle is unnecessary. Because the dunite conductivity is consistent with that published for single crystals under similar conditions, the authors have made a combined analysis of these data. Conductivity as a function of temperature between 600 and 1,450 C displays three conduction mechanisms whose activation energies may be recovered by nonlinear least squares fitting, yielding activation energies of 0.21 {plus minus} 2.56 {times} 10{sup {minus}19} J below 720 C, 2.56 {plus minus} 0.02 {times} 10{sup {minus}19} J between 720 C and 1,500 C and 11.46 {plus minus} 0.90 {times} 10{sup {minus}19} J above 1,500 C. The behavior of conductivity as a function of oxygen fugacity is well explained by a model in which an f{sub O{sub 2}}-independent population of charge carriers is supplemented at high oxygen fugacities with a population that is proportional to f{sub O{sub 2}}{sup 0.3}. This parametrization produces a clear correlation of the f{sub O{sub 2}} dependent term with iron content, which is otherwise obscured by variations in conductivity among olivines.

Constable, S. (Scripps Inst. of Oceanography, La Jolla, CA (United States)); Duba, A. (Lawrence Livermore National Lab., CA (United States))

1990-05-10

211

An antiresonance theory in weakly electrically conducting ferromagnets  

Microsoft Academic Search

A macroscopic theory of the antiresonance effect (AR) was investigated in weakly electrically conducting ferromagnetic metals in the parallel configuration by solving the Maxwell equations (including the displacement current) and the Landau-Lifschitz equation of motion (including a weak magnetocrystalline anisotropy). The analytical expressions for the AR conditions, the dispersion relations, the surface impedance, the line width and the AR transmission

Ngoc Chan; D. Fraitová

1982-01-01

212

Ion induced electrical conductivity versus chemical doping in polyaniline (PANI)  

Microsoft Academic Search

The effect of ion implantation on the electrical conducting behavior of neutral polyaniline (EB) has been studied and this is compared with the result of chemical doping (ES). The damage caused by ion implantation was analyzed with 4He+ Rutherfold backscattering spectroscopy. The experimental results indicate that the value of the resistivity in the carbon-rich layer of EB resulted from the

Zhi Shen Tong; Mei Zhen Wu; Jiu Long Ding; Qun Hua Hu; Min Zhu; Lei Chen; Xing Long Xu; Mei Xiang Wan; Huai Xia Zhou

1992-01-01

213

Image theory for electric dipoles above a conducting anisotropic earth  

Microsoft Academic Search

New image representations for vertical electric dipoles (VED) above an imperfectly conducting and axially anisotropic earth are developed. These include multidiscrete images at different depths below the air-earth interface and multipole image sources. It is shown that, in contrast with the available image representations in the literature, the developed ones predict the correct behavior of the fields in the far

S. F. Mahmoud

1984-01-01

214

Identification of contaminated soils by dielectric constant and electrical conductivity  

Microsoft Academic Search

To develop effective decontamination methods, characterization and identification of contaminated soils are needed. However, current methods of environmental soil characterization involve either soil sampling and analysis for targeted species in the laboratory or soil electrical conductivity measurements. Soil sampling and analyzing in the laboratory involves the risk of sample contamination during handling and testing. Furthermore, it is destructive. To overcome

Abidin Kaya; Hsai-Yang Fang

1997-01-01

215

Temperature dependence of electrical conductivity and the probability density function  

Microsoft Academic Search

The temperature dependence of electrical conductivity for many materials is shown to follow a function G(E, T) that is the derivative of the Fermi function with respect to temperature. It is noted that the Fermi function is a cumulative probability function. It then follows that the probability density function that is used in the calculation of the electron density in

P. Love

1983-01-01

216

Dimensionality switching in electric conduction in FeS  

Microsoft Academic Search

Orbital degree of freedom plays an essential role in the properties of strongly correlated systems, and will be a key function in the next generation. The orbital state, namely, shape of electron cloud, can affect some macroscopic properties such as transport properties. We have indeed observed a dimensionality change in electric conduction in stoichiometric iron sulfide, FeS, as a consequence

Tomohiro Takayama; Kohshi Takenaka; Hidenori Takagi

2006-01-01

217

Terahertz-wave Scattering by Perfectly Electrical Conducting Objects  

Microsoft Academic Search

The prediction of radar cross section (RCS) to perfectly electrical conducting (PEC) objects in the Terahertz band has been discussed in this paper. Since the integral equation solvers cannot offer the ability to compute RCS in such high frequencies, the physical optics (PO) method has been applied. Through properly manipulating to the double integration appeared in PO, the exact integration

X. J. Zhong; T. J. Cui; Z. Li; Y. B. Tao; H. Lin

2007-01-01

218

Dielectric permittivity and electrical conductivity of polycrystalline materials  

Microsoft Academic Search

This paper examines the influence of composition, structure, and size factor on the dielectric permittivity and electrical\\u000a conductivity of polycrystalline materials. We demonstrate that, if the 3D structure of a substance remains unchanged, reducing\\u000a the grain size increases its permittivity, up to 105–106 for nanocrystalline powders.

S. S. Batsanov; V. I. Galko; K. V. Papugin

2010-01-01

219

Structure and electrical conduction properties of phthalocyanine thin films  

Microsoft Academic Search

The structure and the dc and ac electrical conduction properties of evaporated phthalocyanine thin films are critically reviewed.Results of various structural studies on phthalocyanine single crystals and thin films performed using X-ray diffraction methods are described, and reported unit cell dimensions are given for several phthalocyanines in both the metastable ? and the stable ? forms: reported unit cell dimensions

R. D. Gould

1996-01-01

220

Characterization of electrically conductive transition metal dichalcogenide lubricant films  

Microsoft Academic Search

Groups VB and VIB transition metal dichalcogenides with layered structures, are intrinsic solid lubricants, and constitute a class of materials with unique and unusual properties based on their extreme anisotropy. The primary objective of this investigation was to conduct a comprehensive study on the tribological and electrical properties of burnished and sputtered transition metal dichalcogenide films, and characterize the performance

Harish C. Waghray

1997-01-01

221

Modeling the passive cardiac electrical conductivity during ischemia  

Microsoft Academic Search

A geometrical model of cardiac tissue was used to compute the bidomain conductivities. We simulated ischemic conditions by adapting the geometrical model to morphological and electrical changes reported in literature. The simulated changes included 1) expansion of capillaries 2) cell swelling and 3) the closure of gap junctions, which coincide with changes associated with the three phases of ischemia reported

Jeroen G. Stinstra; Shibaji Shome; Bruce Hopenfeld; Rob S. Macleod

222

Unconventional approaches to combine optical transparency with electrical conductivity  

Microsoft Academic Search

The combination of electrical conductivity and optical transparency in the same material - known to be a prerogative of only a few oxides of post-transition metals, such as In, Sn, Zn and Cd - manifests itself in a distinctive band structure of the transparent conductor host. While the oxides of other elements with s2 electronic configuration, for example, Mg, Ca,

J. E. Medvedeva

2007-01-01

223

Electrical Conductivity of Lambda DNA-Pd Wire  

Microsoft Academic Search

We investigated the electric conduction of lambda DNA molecules covered with Pd colloids using micromachined DNA tweezers that has a pair of opposing probes for retrieving DNA molecules. The molecules were retrieved from a solution containing lambda DNA by applying RF power between the probes in the solution. The retrieved molecules were then soaked in a colloidal solution containing cationic

Maho Hosogi; Gen Hashiguchi; Masa-aki Haga; Tetsu Yonezawa; Kuniyuki Kakushima; Hiroyuki Fujita

2005-01-01

224

High temperature electrical conductivity of rigid polyurethane foam  

SciTech Connect

The temperature dependence of the electrical conductivity of three rigid polyurethane foams prepared using different formulations has been measured to approx. 320/sup 0/C. The materials exhibit similar conductivity characteristics, showing a pronounced increase in conductivity with increasing temperature. The insulating characteristics to approx. 200/sup 0/C are better than that for phenolic materials (glass fabric reinforced), and are similar to those for silicone materials (glass microsphere reinforced). At higher temperatures (500 to 600/sup 0/C), the phenolics and silicones are better insulators.

Johnson, R.T. Jr.

1984-03-01

225

Electrical conductivity and dielectric property of fly ash geopolymer pastes  

NASA Astrophysics Data System (ADS)

The electrical conductivity and dielectric property of fly ash geopolymer pastes in a frequency range of 100 Hz-10 MHz were studied. The effects of the liquid alkali solution to ash ratios (L/A) were analyzed. The mineralogical compositions and microstructures of fly ash geopolymer materials were also investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The 10 mol sodium hydroxide solution and sodium silicate solution at a sodium silicate-to-sodium hydroxide ratio of 1.0 were used in making geopolymer pastes. The pastes were cured at 40°C. It is found that the electrical conductivity and dielectric constant are dependent on the frequency range and L/A ratios. The conductivity increases but the dielectric constant decreases with increasing frequency.

Hanjitsuwan, Sakonwan; Chindaprasirt, Prinya; Pimraksa, Kedsarin

2011-02-01

226

Contactless electrical conductivity measurement of electromagnetically levitated metallic melts  

SciTech Connect

The electrical conductivity {sigma} of metallic liquids is of obvious importance to many liquid metal processing operations, because it controls the melt flow under the influence of electromagnetic fields, e.g. during casting processes, or in crystal growth furnaces. A facility for noninvasive measurements of the electrical conductivity of liquid metals above and below the melting temperature is presented. It combines the containerless positioning method of electromagnetic levitation with the contactless technique of inductive conductivity measurement. Contrary to the conventional measurement method, the sample is freely suspended within the measuring field and, thus, has no exactly predefined shape. This made a new theoretical basis necessary with implications on the measurement and levitation fields. Furthermore, the problem of the mutual inductive interactions between the levitation and the measuring coils had to be solved.

Richardsen, T.; Lohoefer, G.

1999-07-01

227

On the question of the interrelation between variations in crustal electrical conductivity and geodynamical processes  

NASA Astrophysics Data System (ADS)

The behavior of the variations in the crustal electrical conductivity in a wide range of periods is studied from the data of magnetotelluric soundings (MTS) during the Kambarata experiment (a strong industrial explosion to construct the blast-fill dam on the Naryn river), as well as at Aksu, a stationary geophysical monitoring point. The concept of the interrelation between the stress-strain state of the medium and the change in the apparent electrical resistivity, which is based on the idea of the redistribution of mineralized solutions between the crack networks, is confirmed experimentally. A procedure of azimuthal monitoring is developed, which allowed us not only to identify the anomalous changes in the module and phase of apparent resistivity but also to establish the directions of their maximum increases and decreases (the axes of compression and tension). For 34 points of deep MTS in the territory of Central Tien Shan, the depth intervals in the upper crust that are most sensitive to the changes in the stress-strain state of the medium are established. The variations in the electrical conductivity are compared with the solar-lunar tidal impacts. It is shown that by analyzing the recorded time series, it is possible to recognize the characteristic signs of the changes in the stress-strain state of the medium that are caused by seismic events.

Bataleva, E. A.; Batalev, V. Yu.; Rybin, A. K.

2013-05-01

228

Linear temperature dependence of conductivity in the apparent insulating regime of dilute two-dimensional holes in GaAs  

Microsoft Academic Search

The conductivity of extremely high mobility dilute two-dimensional holes in GaAs changes linearly with temperature in the insulating side of the metal-insulator transition. Hopping conduction, characterized by an exponentially decreasing conductivity with decreasing temperature, is not observed when the conductivity is smaller than e2\\/h. We suggest that strong interactions in a regime close to the Wigner crystallization must be playing

Hwayong Noh; M. P. Lilly; D. C. Tsui; J. A. Simmons; L. N. Pfeiffer; K. W. West

2003-01-01

229

In vivo electrical conductivity measurements during and after tumor electroporation: conductivity changes reflect the treatment outcome  

NASA Astrophysics Data System (ADS)

Electroporation is the phenomenon in which cell membrane permeability is increased by exposing the cell to short high-electric-field pulses. Reversible electroporation treatments are used in vivo for gene therapy and drug therapy while irreversible electroporation is used for tissue ablation. Tissue conductivity changes induced by electroporation could provide real-time feedback of the treatment outcome. Here we describe the results from a study in which fibrosarcomas (n = 39) inoculated in mice were treated according to different electroporation protocols, some of them known to cause irreversible damage. Conductivity was measured before, within the pulses, in between the pulses and for up to 30 min after treatment. Conductivity increased pulse after pulse. Depending on the applied electroporation protocol, the conductivity increase after treatment ranged from 10% to 180%. The most significant conclusion from this study is the fact that post-treatment conductivity seems to be correlated with treatment outcome in terms of reversibility.

Ivorra, Antoni; Al-Sakere, Bassim; Rubinsky, Boris; Mir, Lluis M.

2009-10-01

230

Electrical conductivity in lipid bilayer membranes induced by pentachlorophenol.  

PubMed Central

Electrical conductivity induced in thin lipid bilayer membranes by pentachlorophenol has been studied. The membranes were formed from phosphatidyl choline, phosphatidyl ethanolamine, or phosphatidyl glycerol and various amounts of cholesterol. The position and the magnitude of the maximum of the conductivity vs. pH curve depend on the type of lipids and cholesterol content. At low pentachlorophenol concentrations and low pH the concentration dependence of conductivity is quadratic and becomes linear at higher pH. Above 10(-5) M of pentachlorophenol the concentration dependence of the membrane conductivity tends to saturate. Presence of pentachlorophenol enhances membrane transport of nonactin-K+ complex. Increase of cholesterol content increases pentachlorophenol induced conductivity in all membranes and shifts the conductivity toward lower pH. For phosphatidyl choline the largest rate of change of membrane conductivity with cholesterol occurs at 1:1 phospholipid to cholesterol molar ratio. Pentachlorophenol is found to be a class II uncoupler and the experimental results are consistent with the hypothesis that the membrane permeable species are dimers formed by combination of neutral and dissociated pentachlorophenol molecules. Several schemes of membrane conduction, including dimer formation in the aqueous phase as well as at the membrane-water interface have been considered. Arguments are given in favor of the formation of dimers within the membrane surface.

Smejtek, P; Hsu, K; Perman, W H

1976-01-01

231

Electrical Conductivity Measurements on Hydrous Carbonate Melts at Mantle Pressure  

NASA Astrophysics Data System (ADS)

Electromagnetic methods image mantle regions in the asthenosphere with elevated conductivity (0.1 to 1 S.m-1), which constrasts with the conductivity of dry olivine (10-2 to 10-3 S.m-1). A correct interpretation of the petrological nature of the conductive mantle is critical for our understanding of mantle geodynamics because such conductive regions indicate mantle rocks with physical and chemical properties that importantly deviates from the canonical peridotites. For decades, such anomalously high mantle conductivities have been attributed to mineralogical defects associated to few tens of ppm water incorporated in olivine. Most recent experimental surveys, however, refute this hydrous olivine model. Conductive mantle regions could then reflect partial melting. The presence of melts in the Earth's mantle has long been proved by geochemical observations and experimental petrology on peridotite rocks. The requirement for melting in the asthenospheric mantle is the presence of volatile species (water, carbon dioxide, halogens). Small melt fractions are then produced by small volatile contents and they are the first liquids produced by melting magma. This study reports electrical conductivity measurements on such melts at mantle pressure and temperature. We investigated on melt chemical compositions produced by melting of peridotite that would interact with CO2-H2O and Cl. Such melts are carbonatite melts, carbonated silicate melts, hydrous carbonate melts, hydrous basalts. A new system allowing in situ electrical conductivity measurements in piston cylinder has been deployed. This design has been specifically adapted to perfom measurements on liquid samples with elevated electrical conductivities. The chemical compositions investigated are pure liquid CaCO3 and CaMg(CO3)2, to which, cloride (as salts), silicate (as basalts) and water (as brucite) have been added. Experiments have been realized at 1.5 and 2.7 GPa pressure and temperature of 1000-1700° C. Impedance spectrometry measurements are realized using a Solartron gainphase analyser. In the liquid state, which was identified at T varying from 1000-1700° C depending on chemical compositions, all investigated samples are extremely conductive, i.e. >100 S.m-1. It is 10,000 times more conductive than mantle olivine at similar P and T. The conductivities of samples increase with temperature and Arrhenius relationships can be adjusted. Activation energies depend on chemical compositions and vary from 40 to 80 kJ.mol-1. Conductivity of melts increases in the following sequence: CaCO3 < MgCa(CO3)2 < (MgCa(CO3)2)0.9 (NaCl)0.1 < (CaCO3)0.45 (NaCl)0.1 (MgH2O2)0.45. The latter melt composition is a simplified synthetic analogue of fluid inclusions entrapped in diamonds. Its electrical conductivity increases to >200 S.m-1 at 1410° C and 2.7 GPa. An electromagnetic survey (Tarits et al, this session) identifies a conductive mantle underneath mid-ocean ridge from 100 to nearly 500 km of depth. The determined conductivity, 0.1 S.m-1, is obtained considering 0.07 volume % of hydrous carbonated melts in peridotite rocks. This is equivalent to a peridotite with 175 ppm CO2 and 67 ppm water stored as small melt fraction wetting grain boundaries. Geochemical and geodynamic implications are discussed by Gaillard (this session).

Sifre, D.; Gaillard, F.

2012-04-01

232

Investigation of Electrical Conduction in Vanadate Based Glasses  

NASA Astrophysics Data System (ADS)

The binary glassy systems 60V2O5-(40-x)P2O5 -xB2O3 were prepared by melt quenching technique. The mole of B2O3 was varies from 5 to 20 mol % with constant mol % of V2O5 during preparation of glass samples. The dc electrical conductivity of samples was measured in temperature range 303-473 K and found to be higher for sample 60 V2O5-20P2O5 -20B2O3. Using the Arrhenius equation of conductivity, the activation energy of conduction is estimated. The conduction in these glasses is takes place by phonon-assisted hopping between the localized states.

Barde, R. V.; Waghuley, S. A.

233

Effect of Cerium on Mechanical Performance and Electrical Conductivity of Aluminum Rod for Electrical Purpose  

Microsoft Academic Search

The effect of rare earth element Ce on mechanical performance and electrical conductivity of aluminum rod for electrical purpose were studied under industrial production condition. Using optical microscope, SEM, TEM, EDS and X-ray diffractometer, the microstructure and phase composition of aluminum rod were measured and analyzed. The results indicate that the content of rare earth element Ce is between 0.05%

Li Pengfei; Wu Zhigang; Wang Yunli; Gao Xizhu; Wang Zaiyun; Li Zhiqiang

2006-01-01

234

Electrical conductivity of the roof of electric arc steel melting furnaces  

SciTech Connect

The authors test for the relationship between temperature and electrical conductivity in the refractory liners of arc furnaces used by the steel industry in the Soviet Union in order to minimize the degradation of these refractories by electrical and thermal processes, to maximize their service life, and to optimize their insulating properties and the consequent efficiency of the furnaces in which they are utilized.

Osipenko, V.D.; Garbuz, S.S.; Khromov, A.P.

1987-01-01

235

The bedrock electrical conductivity map of the UK  

NASA Astrophysics Data System (ADS)

Airborne electromagnetic (AEM) surveys, when regionally extensive, may sample a wide-range of geological formations. The majority of AEM surveys can provide estimates of apparent (half-space) conductivity and such derived data provide a mapping capability. Depth discrimination of the geophysical mapping information is controlled by the bandwidth of each particular system. The objective of this study is to assess the geological information contained in accumulated frequency-domain AEM survey data from the UK where existing geological mapping can be considered well-established. The methodology adopted involves a simple GIS-based, spatial join of AEM and geological databases. A lithology-based classification of bedrock is used to provide an inherent association with the petrophysical rock parameters controlling bulk conductivity. At a scale of 1:625k, the UK digital bedrock geological lexicon comprises just 86 lithological classifications compared with 244 standard lithostratigraphic assignments. The lowest common AEM survey frequency of 3 kHz is found to provide an 87% coverage (by area) of the UK formations. The conductivities of the unsampled classes have been assigned on the basis of inherent lithological associations between formations. The statistical analysis conducted uses over 8 M conductivity estimates and provides a new UK national scale digital map of near-surface bedrock conductivity. The new baseline map, formed from central moments of the statistical distributions, allows assessments/interpretations of data exhibiting departures from the norm. The digital conductivity map developed here is believed to be the first such UK geophysical map compilation for over 75 years. The methodology described can also be applied to many existing AEM data sets.

Beamish, David

2013-09-01

236

Evaluation of electrical conductivity of Cu and Al through sub microsecond underwater electrical wire explosion  

NASA Astrophysics Data System (ADS)

Sub-microsecond timescale underwater electrical wire explosions using Cu and Al materials have been conducted. Current and voltage waveforms and time-resolved streak images of the discharge channel, coupled to 1D magneto-hydrodynamic simulations, have been used to determine the electrical conductivity of the metals for the range of conditions between hot liquid metal and strongly coupled non-ideal plasma, in the temperature range of 10-60 KK. The results of these studies showed that the conductivity values obtained are typically lower than those corresponding to modern theoretical electrical conductivity models and provide a transition between the conductivity values obtained in microsecond time scale explosions and those obtained in nanosecond time scale wire explosions. In addition, the measured wire expansion shows good agreement with equation of state tables.

Sheftman, D.; Shafer, D.; Efimov, S.; Krasik, Ya. E.

2012-03-01

237

On the correlation of electrical conductivity and heat flow in Middle Valley, Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

The near-surface electrical conductivity has been mapped within an area of Middle Valley, a sediment-filled axial valley at the northern end of the Juan de Fuca ridge. The conductivity in the uppermost 20 m of sediment was determined by analyzing the magnetic field signal transmitted between a source coil and a receiver that were towed along the seafloor. The instrument is a version of a time domain electromagnetic (TDEM) sounding system. The heat flow pattern within Middle Valley, with a large central anomaly above a basement high, is reproduced by the conductivity measurements, the result of enhanced pore fluid electrical conductivity due to higher near-surface temperatures in the high heat flow regions. The high correlation between heat flow and conductivity requires that porosity as inferred from Archie's law must be nearly uniform in the central part of the study area. Porosities derived from the conductivity measurements are in close agreement with measurements from the Ocean Drilling Project (ODP) boreholes. Higher near-surface porosities are required in the eastern part of the valley to match the observed heat flow, consistent with the higher porosity seen at ODP site 855. A small region of apparently lower porosity was detected to the west of the center of the valley.

Webb, Spahr C.; Edwards, R. Nigel

1995-11-01

238

Grain size-dependent electrical conductivity of polycrystalline cerium oxide  

Microsoft Academic Search

The electrical conductivity of polycrystalline cerium oxide was investigated in the nanometer and micrometer size range. Nanocrystalline samples of different grain size were prepared by uniaxial hot-pressing of nanocrystalline powder at various temperatures and pressures. Additional annealing at high temperatures was employed in order to obtain microcrystalline samples. An equivalent-circuit analysis of ac-impedance spectra based on the brick-layer model was

A. Tschöpe; E. Sommer; R. Birringer

2001-01-01

239

Electrical conductivity for warm, dense aluminum plasmas and liquids  

NASA Astrophysics Data System (ADS)

The electrical conductivity of warm, dense aluminum plasmas and liquids is calculated using ab initio molecular dynamics and the Kubo-Greenwood formula. The density range extends from near solid to one-hundredth of solid density, and the temperature range extends from 6000 K to 30 000 K. This density and temperature range allows direct comparison with experimental results obtained with the tamped exploding wire technique.

Desjarlais, M. P.; Kress, J. D.; Collins, L. A.

2002-08-01

240

Electrically Conductive Metal Polymer Nanocomposites for Electronics Applications  

Microsoft Academic Search

An electrically conductive nanocomposite composed of thermoplastic elastomer and nanosized silver particles was developed.\\u000a Nanosized silver particles were produced by the liquid flame spraying method. Nanocomposites were produced employing a batch\\u000a mixing process in the melt state. The percolation curve and the minimum resistivity as a function of silver content were defined.\\u000a A plasticized styrene block-copolymer was used as the

Mikko Karttunen; Pekka Ruuskanen; Ville Pitkänen; Willem M. Albers

2008-01-01

241

Effects of interface on electrical conduction in epoxy resin composites  

Microsoft Academic Search

The effects of the epoxy-resin interface on electronic conduction were studied by using photocurrent and thermally stimulated current techniques. The electrical properties of epoxy-filler composites are greatly affected by the interfaces in various ways depending on applied field, temperature, carrier species, and mechanical stress. At low temperature, electronic carriers transported from the epoxy layer in epoxy-alumina composites can pass through

A. Kawamoto; Y. Suzuoki; T. Ikejiri; T. Mizutani; M. Ieda

1991-01-01

242

Synthesis and applications of electrically conducting polymer nanocomposites  

Microsoft Academic Search

This research focuses on the synthesis and applications of electrically conducting polymer nanocomposites through molecular self-assembly. Two different classes of polymers, polyaniline (PANI) and polyacetylenes have been synthesized by biomimetic catalysis and spontaneous polymerization method. For gas barrier materials, commercially available polymers, poly(allylamine hydrochloride) (PAH) and poly (acrylic acid) (PAA), have also been used and thermally cross-linked. The morphological, optical

Bon-Cheol Ku

2005-01-01

243

Electrical conductivity and total dissolved solids in urine  

Microsoft Academic Search

The objective of this paper is to study the relevance of electrical conductivity (EC) and total dissolved solids (TDS) in\\u000a early morning and random samples of urine of urinary stone patients; 2,000 urine samples were studied. The two parameters\\u000a were correlated with the extent of various urinary concrements. The early morning urine (EMU) and random samples of the patients\\u000a who

Y. M. Fazil Marickar

2010-01-01

244

Anisotropy of the Electrical Conductivity in Bismuth Telluride  

Microsoft Academic Search

The anisotropy of the electrical conductivity of Bi2Te3 at room temperature has been determined by a four-probe method. The anisotropy ratio for undoped p-type material is close to 3.0; for iodine-doped n-type material it is appreciably higher and increases with the impurity concentration. Measurements of the galvanomagnetic effects in highly doped n-type Bi2Te3 have shown that the observed variation of

R T Delves; A E Bowley; D W Hazelden; H J Goldsmid

1961-01-01

245

Nanotube Networks in Polymer Nanocomposites: Rheology and Electrical Conductivity  

Microsoft Academic Search

Single-walled carbon nanotube (SWNT)\\/poly(methyl methacrylate) (PMMA) nanocomposites were prepared via our coagulation method providing uniform dispersion of the nanotubes in the polymer matrix. Optical microscopy, Raman imaging, and SEM were employed to determine the dispersion of nanotube at different length scales. The linear viscoelastic behavior and electrical conductivity of these nanocomposites were investigated. At low frequencies, Gbecomes almost independent of

Fangming Du; Robert C. Scogna; Wei Zhou; Stijn Brand; John E. Fischer; Karen I. Winey

2004-01-01

246

Electrical conduction in some sol-gel silicate glasses  

Microsoft Academic Search

Measurements are reported for the electrical conductivity of different compositions of silicate glasses containing copper and vanadium in the temperature range 200-500 K. The experimental results for the two systems are found to be very similar and are analyzed with respect to theoretical models existing in the literature. At high temperatures, Mott's model of phonon-assisted small-polaron hopping between nearest neighbors

A. Ghosh; D. Chakravorty

1993-01-01

247

The effects of oxidation on the electrical conduction of polyethylene  

Microsoft Academic Search

The effects of oxidation on the electrical conduction of low- and high-density polyethylene (LD-PE and HD-PE) have been studied. It has been found that oxidation enhances the carrier mobility in LD-PE, but lowers that in HD-PE. A qualitative explanation of these opposing effects is given, based on the assumption that carbonyl groups introduced in the amorphous regions of PE act

T. Mizutani; T. Tsukahara; M. Ieda

1980-01-01

248

An Overview of Earth's Global Electric Circuit and Atmospheric Conductivity  

Microsoft Academic Search

The Earth's global atmospheric electric circuit depends on the upper and lower atmospheric boundaries formed by the ionosphere and the planetary surface. Thunderstorms and electrified rain clouds drive a DC current (˜1 kA) around the circuit, with the current carried by molecular cluster ions; lightning phenomena drive the AC global circuit. The Earth's near-surface conductivity ranges from 10-7 S m-1

Michael J. Rycroft; R. Giles Harrison; Keri A. Nicoll; Evgeny A. Mareev

2008-01-01

249

Electrical conductivity of dense nanocrystalline ceria under humidified atmosphere  

Microsoft Academic Search

This paper describes the water adsorption behavior and electrical conductivity of Sm-doped ceria nanoparticles under humidified atmosphere. Single nano-sized 6 mol% Sm-doped ceria was prepared by either homogeneous precipitation using hexamethylenetetramine (HMTA) or ultraviolet (UV) laser irradiation. For the ceria nanoparticles prepared by HMTA, weakly-bundled agglomerates with pores were formed; as a result, approximately 3 mass% of water adsorption and capillary

Hitoshi Takamura; Naomi Takahashi

2010-01-01

250

DC electrical conductivity of polydithiooxamide–metal complexes  

Microsoft Academic Search

Five polymer–metal complexes of iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) were prepared from the reaction of dithiooxamide with metal salts. Elemental analysis, UV–VIS and IR investigations were carried out for the polymer complexes. The temperature variation of the DC electrical conductivity was measured in the range 298–498 K for the five polymer complexes. The proposed mechanism for the variation is

Ali El-Shekeil; Maarib A Khalid; Hussein Al-Maydama; Ashour Al-Karbooly

2001-01-01

251

The Electrical Conductivity of Packed Beds Containing Macroporous Cation Exchanger  

Microsoft Academic Search

The electrical conductivity of packed beds containing macroporous Duolite C-25 polystyrene sulfonate cation exchanger equilibrated with aqueous solutions of a single electrolyte (NaCl or HCl) has been measured over a range of electrolyte concentrations. The results are interpreted in terms of a two-phase model for the resin particle involving (1) the resin matrix, with the conventional properties of polystyrene sulfonate

Darryl G. Howery; Sugihiko Tada

1969-01-01

252

Unconventional approaches to combine optical transparency with electrical conductivity  

Microsoft Academic Search

The combination of electrical conductivity and optical transparency in the same material – known to be a prerogative of only\\u000a a few oxides of post-transition metals, such as In, Sn, Zn and Cd – manifests itself in a distinctive band structure of the\\u000a transparent conductor host. While the oxides of other elements with s2 electronic configuration, for example, Mg, Ca,

J. E. Medvedeva

2007-01-01

253

On the electrical conductivity of Ti-implanted alumina  

NASA Astrophysics Data System (ADS)

Ion implantation of metal species into insulators provides a tool for the formation of thin, electrically conducting, surface layers with experimenter-controlled resistivity. High energy implantation of Pt and Ti into alumina accelerator components has been successfully employed to control high voltage surface breakdown in a number of cases. In the work described here we have carried out some basic investigations related to the origin of this phenomenon. By comparison of the results of alumina implanted with Ti at 75 keV with the results of prior investigations of polymers implanted with Pt at 49 eV and Au at 67 eV, we describe a physical model of the effect based on percolation theory and estimate the percolation parameters for the Ti-alumina composite. We estimate that the percolation dose threshold is about 4 × 1016 cm-2 and the maximum dose for which the system remains an insulator-conductor composite is about 10 × 1016 cm-2. The saturation electrical conductivity is estimated to be about 50 S/m. We conclude that the observed electrical conductivity properties of Ti-implanted alumina can be satisfactorily described by percolation theory.

Salvadori, M. C.; Teixeira, F. S.; Cattani, M.; Nikolaev, A.; Savkin, K. P.; Oks, E. M.; Park, H.-K.; Phillips, L.; Yu, K. M.; Brown, I. G.

2012-03-01

254

Electrical conduction in ammonium and alkali metal perchlorates  

NASA Astrophysics Data System (ADS)

Experimental results on the temperature and frequency dependence of the ac electrical conductivity of rubidium perchlorate (RbP) and cesium perchlorate (CsP) are presented. Studies were carried out in the temperature range from ambient to approximately 300 C and at frequencies ranging from 50 Hz to 1 kHz. Both nominally pure compounds and those doped with Cr4(2-), SO4(-2), and Mn(2+) were studied. The electrical conduction behavior of these materials is compared with that previously observed in this laboratory for potassium perchlorate (KP) with a view to highlight some common features. Results previously reported on an analogous material - ammonium perchlorate (AP) - are critically examined in light of the present data. A unified defect-structure model is fully presented. This model emphasizes similarities in the electrical conduction behavior of the above compounds. The experimental results on AP seem to be more consistent with this model than with the currently accepted proton transfer mechanism.

Rajeshwar, K.; Nottenburg, R.; Dubow, J.; Pai Verneker, V. R.

1980-06-01

255

On the electrical conductivity of Ti-implanted alumina  

SciTech Connect

Ion implantation of metal species into insulators provides a tool for the formation of thin, electrically conducting, surface layers with experimenter-controlled resistivity. High energy implantation of Pt and Ti into alumina accelerator components has been successfully employed to control high voltage surface breakdown in a number of cases. In the work described here we have carried out some basic investigations related to the origin of this phenomenon. By comparison of the results of alumina implanted with Ti at 75 keV with the results of prior investigations of polymers implanted with Pt at 49 eV and Au at 67 eV, we describe a physical model of the effect based on percolation theory and estimate the percolation parameters for the Ti-alumina composite. We estimate that the percolation dose threshold is about 4 x 10{sup 16} cm{sup -2} and the maximum dose for which the system remains an insulator-conductor composite is about 10 x 10{sup 16} cm{sup -2}. The saturation electrical conductivity is estimated to be about 50 S/m. We conclude that the observed electrical conductivity properties of Ti-implanted alumina can be satisfactorily described by percolation theory.

Salvadori, M. C.; Teixeira, F. S.; Cattani, M. [Institute of Physics, University of Sao Paulo, C.P. 66318, CEP 05315-970, Sao Paulo S.P. (Brazil); Nikolaev, A.; Savkin, K. P.; Oks, E. M. [High Current Electronics Institute, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Park, H.-K.; Phillips, L. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Yu, K. M.; Brown, I. G. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2012-03-15

256

Method for electrically isolating an electrically conductive member from another such member  

DOEpatents

The invention relates to methods for electrically isolating a first electrically conductive member from another such member by means of an electrically insulating medium. In accordance with the invention, the insulating medium is provided in the form of MgO which contains a dopant selected from lithium, copper, cobalt, sodium, silver, gold and hydrogen. The dopant is present in the MgO in an amount effective to suppress dielectric breakdown of the MgO, even at elevated temperatures and in the presence of electrical fields.

Tsang, K.L.; Chen, Y.

1984-02-09

257

Electrical conductivity of shock-compressed PVDF films  

NASA Astrophysics Data System (ADS)

Time-dependent conductivity of unpolarized PVDF films has been studied over a wide range of shock pressures. Two types of PVDF films were investigated. They were a 30-micron uni-axially-stretched modified PVDF film (4% tetrafluoroethylene) and a 25-micron bi-axially-stretched pure PVDF film. Shock wave experiments were performed on two conductivity cell configurations. The first represented four layers of the film clamped between two metal electrodes in the geometry of a parallel-plate capacitor. The second was a gauge arrangement with a pattern similar to that used by Bauer of ISL, France, mounted in Teflon for the tests. Observations were made for 1 to 2 microseconds after shock arrival. The onset of electrical conductivity was detected at 10 GPa for the modified film, whereas, this event was detected at approximately 28 GPa for the pure film.

Yakushev, V. V.; Yakusheva, T. I.

1998-07-01

258

Using High Resolution Complex Electrical Conductivity Measurements of Heterogeneous Rocks  

NASA Astrophysics Data System (ADS)

The complex electrical resistivity of a slab of Berea sandstone was measured using a four electrode probe in the frequency range of 1 Hz to 1 kHz. The measurements where made in the context of the development of a new high resolution methodology for the laboratory characterization of hydro-geophysical properties on core and field samples. Electrical conductivity maps with millimeter-scale resolution and measured at different pore fluid salinities are used to constrain dual conduction models (e.g. Waxman-Smits, 1968) that allow us to separate the contribution of electrical conduction through the pore fluid from surface conduction along mineral grain surfaces. Measured resistivity variations are observed to be structured in distinct layers at the scale of millimeters to centimeters and are well correlated with fine scale layering observed in thin section. The data is analyzed in conjunction with petrophysical maps of permeability and velocity variations. The maps of permeability, resistivity, and velocity all indicate that Berea sandstone contains measurable structural anisotropy at a variety of scales. The heterogeneities in petrophysical properties are in general rather weak, with permeability varying by a factor of 3 and velocity and resistivity varying by 7% and 19% respectively. Analyzed collectively, the data provides insights into the physical causes of the observed resistivity anomalies and allows us to interpret them as due to localized pore-scale variations in grain size, pore structure, and mineralogy. Correlations among these petrographic variables lead to the discovery that surface conductivity of the rock is negatively correlated with the conductivity due to the free electrolyte. Using this integrated petrophysical data-set, we build a predictive model of the meter-scale petrophysical properties that honors the intrinsic heterogeneity of the sample. The data and models are used as the foundation for a physically-based upscaling approach for understanding how petrophysical properties relate to flow and transport processes at scales difficult to measure in the laboratory. Through application of effective media and numerical models we show that the observed small-scale heterogeneity leads to anisotropy in electrical properties that correlates with anisotropy in relative permeability. The anisotropy is found to be a complex function of scale, salinity, and saturation.

Boitnott, G. N.; Bussod, G. Y.

2009-12-01

259

An Overview of Earth's Global Electric Circuit and Atmospheric Conductivity  

NASA Astrophysics Data System (ADS)

The Earth’s global atmospheric electric circuit depends on the upper and lower atmospheric boundaries formed by the ionosphere and the planetary surface. Thunderstorms and electrified rain clouds drive a DC current (˜1 kA) around the circuit, with the current carried by molecular cluster ions; lightning phenomena drive the AC global circuit. The Earth’s near-surface conductivity ranges from 10-7 S m-1 (for poorly conducting rocks) to 10-2 S m-1 (for clay or wet limestone), with a mean value of 3.2 S m-1 for the ocean. Air conductivity inside a thundercloud, and in fair weather regions, depends on location (especially geomagnetic latitude), aerosol pollution and height, and varies from ˜10-14 S m-1 just above the surface to 10-7 S m-1 in the ionosphere at ˜80 km altitude. Ionospheric conductivity is a tensor quantity due to the geomagnetic field, and is determined by parameters such as electron density and electron-neutral particle collision frequency. In the current source regions, point discharge (coronal) currents play an important role below electrified clouds; the solar wind-magnetosphere dynamo and the unipolar dynamo due to the terrestrial rotating dipole moment also apply atmospheric potential differences. Detailed measurements made near the Earth’s surface show that Ohm’s law relates the vertical electric field and current density to air conductivity. Stratospheric balloon measurements launched from Antarctica confirm that the downward current density is ˜1 pA m-2 under fair weather conditions. Fortuitously, a Solar Energetic Particle (SEP) event arrived at Earth during one such balloon flight, changing the observed atmospheric conductivity and electric fields markedly. Recent modelling considers lightning discharge effects on the ionosphere’s electric potential (˜+250 kV with respect to the Earth’s surface) and hence on the fair weather potential gradient (typically ˜130 V m-1 close to the Earth’s surface. We conclude that cloud-to-ground (CG) lightning discharges make only a small contribution to the ionospheric potential, and that sprites (namely, upward lightning above energetic thunderstorms) only affect the global circuit in a miniscule way. We also investigate the effects of mesoscale convective systems on the global circuit.

Rycroft, Michael J.; Harrison, R. Giles; Nicoll, Keri A.; Mareev, Evgeny A.

2008-06-01

260

The effect of electrical conductivity on pore resistance and electroporation  

NASA Astrophysics Data System (ADS)

Electroporation is an elegant means to gain access to the cytoplasm, and to deliver molecules into the cell while simultaneously maintaining viability and functionality. In this technique, an applied electric pulse transiently permeabilizes the cell membrane, through which biologically active agents such as DNA, RNA, and amino acids can enter the cell, and perform tasks such as gene and cancer therapy. Despite wide applications, current electroporation technologies fall short of desired efficiency and reliability, in part due to the lack of fundamental understanding and quantitative modeling tools. This work focuses on the modeling of cell membrane conductance due to the formation of aqueous conducting pores. An analytical expression is developed to determine effective pore resistance as a function of the membrane thickness, pore size, and intracellular and extracellular conductivities. The availability of this expression avoids empirical or ad hoc specification of the conductivity of the pore-filling solution which was adopted in previous works. Such pore resistance model is then incorporated into a whole-cell electroporation simulation to investigate the effect of conductivity ratio on membrane permeabilization. The results reveal that the degree of permeabilization strongly depends on the specific values of the extracellular and intracellular conductivities.

Li, Jianbo; Lin, Hao

2008-11-01

261

Electrically conductive gold- and copper-metallized DNA origami nanostructures.  

PubMed

This work demonstrates the use of a circuit-like DNA origami structure as a template to fabricate conductive gold and copper nanostructures on Si surfaces. We improved over previous results by using multiple Pd seeding steps to increase seed uniformity and density. Our process has also been characterized through atomic force microscopy, particle size distribution analysis, and scanning electron microscopy. We found that four successive Pd seeding steps yielded the best results for electroless metal plating on DNA origami. Electrical resistance measurements were done on both Au- and Cu-metallized nanostructures, with each showing ohmic behavior. Gold-plated DNA origami structures made under optimal conditions had an average resistivity of 7.0 × 10(-5) ?·m, whereas copper-metallized structures had a resistivity as low as 3.6 × 10(-4) ?·m. Importantly, this is the first demonstration of electrically conductive Cu nanostructures fabricated on either DNA or DNA origami templates. Although resistivities for both gold and copper samples were larger than those of the bulk metal, these metal nanostructures have the potential for use in electrically connecting small structures. In addition, these metallized objects might find use in surface-enhanced Raman scattering experiments. PMID:23419143

Geng, Yanli; Pearson, Anthony C; Gates, Elisabeth P; Uprety, Bibek; Davis, Robert C; Harb, John N; Woolley, Adam T

2013-03-01

262

The bedrock electrical conductivity structure of Northern Ireland  

NASA Astrophysics Data System (ADS)

An airborne geophysical survey of the whole of Northern Ireland has provided over 4.8 M estimates of the bedrock conductivity over the wide range of geological formations present. This study investigates how such data can be used to provide additional knowledge in relation to existing digital geological map information. A by-product of the analysis is a simplification of the spatially aggregated information obtained in such surveys. The methodology used is a GIS-based attribution of the conductivity estimates using a lithological classification of the bedrock formations. A 1:250k geological classification of the data is performed leading to a 56 unit lithological and geostatistical analysis of the conductivity information. The central moments (medians) of the classified data are used to provide a new digital bedrock conductivity map of Northern Ireland with values ranging from 0.32 to 41.36 mS m-1. This baseline map of conductivities displays a strong correspondence with an existing 4 quadrant, chrono-geological description of Northern Ireland. Once defined, the baseline conductivity map allows departures from the norm to be assessed across each specific lithological unit. Bulk electrical conductivity is controlled by a number of petrophysical parameters and it is their variation that is assessed by the procedures employed. The igneous rocks are found to display the largest variability in conductivity values and many of the statistical distributions are multi-modal. A sequence of low-value modes in these data are associated with intrusives within volcanic complexes. These and much older Neoproterzoic rocks appear to represent very low porosity formations that may be the product of rapid cooling during emplacement. By way of contrast, extensive flood basalts (the Antrim lavas) record a well-defined and much higher median value (12.24 mS m-1) although they display complex spatial behaviour in detail. Sedimentary rocks appear to follow the broad behaviours anticipated by standard theoretical descriptions of rock electrical properties that allow for a term due to grain surface conduction (e.g. the presence of clay). Single lithology sedimentary rocks are represented by an increasing set of conductivities through the sequence sandstone (4.91 mS m-1), limestone (8.41 mS m-1) and mudstone (17.85 mS m-1) with argillaceous rocks providing a conductivity of 41.1 mS m-1. In the case of both sandstone and limestone, the single lithology conductivities are significantly less than their mixed lithology counterparts. Mudrocks display a bimodal statistical distribution and an extended analysis of these rocks is carried out across a Carboniferous basin. The results clearly indicate that non-shale mudstones are distinctly less conductive than their shale counterparts. Shale formations display rapid and large movements in conductivity and it is suggested that the observed sensitivity may be due to competing surface conduction effects due to clay and organic material. A study of the variation of conductivity with geological period is also performed. Both a decreasing trend with age and a modulation that peaks in the Triassic period are observed.

Beamish, David

2013-08-01

263

Miniatuization of the flowing fluid electric conductivity loggingtec hnique  

SciTech Connect

An understanding of both the hydraulic properties of the aquifer and the depth distribution of salts is critical for evaluating the potential of groundwater for conjunctive water use and for maintaining suitable groundwater quality in agricultural regions where groundwater is used extensively for irrigation and drinking water. The electrical conductivity profiles recorded in a well using the flowing fluid electric conductivity logging (FEC logging) method can be analyzed to estimate interval specific hydraulic conductivity and estimates of the salinity concentration with depth. However, irrigation wells that are common in agricultural regions have limited access into them because these wells are still in operation, and the traditional equipment used for FEC logging cannot fit through the small access pipe intersecting the well. A modified, miniaturized FEC logging technique was developed such that this logging method could be used in wells with limited access. In addition, a new method for injecting water over the entire screened interval of the well was developed to reduce the time required to perform FEC logging. Results of FEC logging using the new methodology and miniaturized system in two irrigation wells are also summarized.

Su, Grace W.; Quinn, Nigel W.T.; Cook, Paul J.; Shipp, William

2005-10-19

264

Effect of water on the electrical conductivity of lower crustal clinopyroxene  

Microsoft Academic Search

Electrical conductivity measurement of lower crustal clinopyroxeneH largely enhances the electrical conductivity of lower crustal clinopyroxeneLower crustal high conductivity may be caused by the main assemblages themselves

Xiaozhi Yang; Hans Keppler; Catherine McCammon; Huaiwei Ni; Qunke Xia; Qicheng Fan

2011-01-01

265

Transparent electrical conducting films by activated reactive evaporation  

DOEpatents

Process and apparatus for producing transparent electrical conducting thin films by activated reactive evaporation. Thin films of low melting point metals and alloys, such as indium oxide and indium oxide doped with tin, are produced by physical vapor deposition. The metal or alloy is vaporized by electrical resistance heating in a vacuum chamber, oxygen and an inert gas such as argon are introduced into the chamber, and vapor and gas are ionized by a beam of low energy electrons in a reaction zone between the resistance heater and the substrate. There is a reaction between the ionized oxygen and the metal vapor resulting in the metal oxide which deposits on the substrate as a thin film which is ready for use without requiring post deposition heat treatment.

Bunshah, Rointan (Los Angeles, CA); Nath, Prem (Troy, MI)

1982-01-01

266

Molecular conductivity switching of two benzene rings under electric field  

NASA Astrophysics Data System (ADS)

A molecular transistor based on torsion-angle conformation change driven by gate electric field is designed and studied using ab initio calculations. This transistor consists of a SH-C6H2F(CH3)C6H2(CH3)F-SH molecule sandwiched between two Au(111) electrodes, where the interaction between the molecular dipole and a gate voltage induced electric field will cause the molecule to twist along its c-axis, changing the quantum conductivity of the molecule. The effect of thermal fluctuation on the molecular conformation is studied, so is the ability of the transistor to shut off its current. The advantages and challenges of using such molecular conformation change as a mechanism for transistor gating are discussed.

Vergniory, M. G.; Granadino-Roldan, J. M.; Garcia-Lekue, A.; Wang, Lin-Wang

2010-12-01

267

Transparent electrical conducting films by activated reactive evaporation  

DOEpatents

Process and apparatus for producing transparent electrical conducting thin films by activated reactive evaporation is disclosed. Thin films of low melting point metals and alloys, such as indium oxide and indium oxide doped with tin, are produced by physical vapor deposition. The metal or alloy is vaporized by electrical resistance heating in a vacuum chamber, oxygen and an inert gas such as argon are introduced into the chamber, and vapor and gas are ionized by a beam of low energy electrons in a reaction zone between the resistance heater and the substrate. There is a reaction between the ionized oxygen and the metal vapor resulting in the metal oxide which deposits on the substrate as a thin film which is ready for use without requiring post deposition heat treatment. 1 fig.

Bunshah, R.; Nath, P.

1982-06-22

268

Ionospheric electrical conductances produced by auroral proton precipitation  

NASA Astrophysics Data System (ADS)

From incoherent scatter radar observations and space-borne particle detector data, it appears that energetic proton precipitation can sometimes, for some locations, be a major source of ionization in the auroral ionosphere and contribute significantly to the electrical conductances. Here we propose a simple parameterization for the Pedersen and Hall conductances produced by proton precipitation. The derivation is based on a proton transport code for computing the electron production rate and on an effective recombination coefficient for deducing the electron density. The atmospheric neutral densities and temperatures and the geomagnetic-field strength are obtained from standard models. The incident protons are assumed to have a Maxwellian distribution in energy with a mean energy in the 2-40 keV range and an energy flux Q0. The parameterized Pedersen and Hall conductances are functions of and Q0, as well as of the geomagnetic-field strength. The dependence on these quantities is compared with those obtained for electron precipitation and for solar EUV radiation. To add the contribution of proton precipitation to the total conductances for electrodynamic studies in auroral regions, the conductances produced by electron and proton precipitations can be combined by applying a root-sum-square approximation.

Galand, Marina; Richmond, Arthur D.

2001-01-01

269

Electrical Conductivities of Liquid Transition Metal-Te Alloys  

NASA Astrophysics Data System (ADS)

The electrical conductivities of liquid Fe-Te, Co-Te and Ni-Te systems increase with increasing transition metal (TM) concentration. The values of conductivity obtained at 1200°C are 2980, 3780 and 5260 ohm-1\\cdotcm-1 for the composition FeTe, CoTe and NiTe, respectively. However, the conductivities of liquid Ti-Te, V-Te and Cr-Te alloys decrease with increasing TM concentration. Moreover, the liquid Mn-Te system exhibits a sharp minimum at the composition MnTe. The values of conductivity obtained at 1200°C are 1710 and 22 ohm-1\\cdotcm-1 for the composition CrTe and MnTe, respectively. The corresponding data for magnetic susceptibility indicate that the density of d-like states at the Fermi level EF is fairly large for liquid CoTe and NiTe and small for liquid MnTe. The conductivities of liquid TM-Te alloys are closely related to the density of d-like states at EF.

Okada, Tatsuya; Ohno, Satoru

1987-03-01

270

Electrical conduction in chalcogenide glasses of phase change memory  

NASA Astrophysics Data System (ADS)

Amorphous chalcogenides have been extensively studied over the last half century due to their application in rewritable optical data storage and in non-volatile phase change memory devices. Yet, the nature of the observed non-ohmic conduction in these glasses is still under debate. In this review, we consolidate and expand the current state of knowledge related to dc conduction in these materials. An overview of the pertinent experimental data is followed by a review of the physics of localized states that are peculiar to chalcogenide glasses. We then describe and evaluate twelve relevant transport mechanisms with conductivities that depend exponentially on the electric field. The discussed mechanisms include various forms of Poole-Frenkel ionization, Schottky emission, hopping conduction, field-induced delocalization of tail states, space-charge-limited current, field emission, percolation band conduction, and transport through crystalline inclusions. Most of the candidates provide more or less satisfactory fits of the observed non-linear IV data. Our analysis calls upon additional studies that would enable one to discriminate between the various alternative models.

Nardone, M.; Simon, M.; Karpov, I. V.; Karpov, V. G.

2012-10-01

271

Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes  

SciTech Connect

Carbon nanotubes (CNT) based polymer composites have emerged as the future multifunctional materials in view of its exceptional mechanical, thermal and electrical properties. One of the major interests is to develop conductive polymer composites preferably at low concentration of CNT utilizing their high aspect ratio (L/D) for numerous applications, which include antistatic devices, capacitors and materials for EMI shielding. In this context, polymer blends have emerged as a potential candidate in lowering the percolation thresholds further by the utilization of 'double-percolation' which arises from the synergistic improvements in blend properties associated with the co-continuous morphology. Due to strong inter-tube van der Waals' forces, they often tend to aggregate and uniform dispersion remains a challenge. To overcome this challenge, we exploited sodium salt of 6-aminohexanoic acid (Na-AHA) which was able to assist in debundlling the multiwall carbon nanotubes (MWNT) through 'cation-{pi}' interactions during melt-mixing leading to percolative 'network-like' structure of MWNT within polyamide6 (PA6) phase in co-continuous PA6/acrylonitrile butadiene styrene (ABS) blends. The composite exhibited low electrical percolation thresholds of 0.25 wt% of MWNT, the lowest reported value in this system so far. Retention of 'network-like structure' in the solid state with significant refinement was observed even at lower MWNT concentration in presence Na-AHA, which was assessed through AC electrical conductivity measurements. Reactive coupling was found to be a dominant factor besides 'cation-{pi}' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.

Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India)

2008-10-23

272

Control of electrical conduction in DNA using hole doping  

Microsoft Academic Search

Control of electrical conduction in DNA using hole doping H.Y.Lee1, M.Taniguchi1, K.H.Yoo2, Y.Otsuka1 H.Tanaka1 and T.Kawai1 1The Institute of Scientific and Industrial Research(ISIR), Osaka University, Osaka, Japan. 2Department of Physics, Younsei University, Seoul, Korea Possible applications of DNA molecules in electronic devices and biosensors were suggested almost ten years ago A DNA structure containing a single type of base pair

Hea-Yeon Lee; Masateru Taniguchi; K. H. Yoo; Youichi Otsuka; Hidekazu Tanaka; Tomoji Kawai

2002-01-01

273

Electrical conductivity of orthopyroxene and plagioclase in the lower crust  

Microsoft Academic Search

The electrical conductivities of lower crustal orthopyroxene and plagioclase, as well as their dependence on water content,\\u000a were measured at 6–12 kbar and 300–1,000°C on both natural and pre-annealed samples prepared from fresh mafic xenolith granulites.\\u000a The complex impedance was determined in an end-loaded piston cylinder apparatus by a Solarton-1260 Impedance\\/Gain Phase analyzer\\u000a in the frequency range of 0.1–106 Hz.

Xiaozhi Yang; Hans Keppler; Catherine McCammon; Huaiwei Ni

2011-01-01

274

Electrical Conductivity of Lambda DNA-Pd Wire  

NASA Astrophysics Data System (ADS)

We investigated the electric conduction of lambda DNA molecules covered with Pd colloids using micromachined DNA tweezers that has a pair of opposing probes for retrieving DNA molecules. The molecules were retrieved from a solution containing lambda DNA by applying RF power between the probes in the solution. The retrieved molecules were then soaked in a colloidal solution containing cationic Pd particles, which results in a DNA-Pd wire bridged between the tweezer probes. Current-voltage curves for the DNA-Pd wire can be measured between the DNA tweezers probes, and the resistivity of the DNA-Pd wire was approximately 74 ? cm.

Hosogi, Maho; Hashiguchi, Gen; Haga, Masa-aki; Yonezawa, Tetsu; Kakushima, Kuniyuki; Fujita, Hiroyuki

2005-07-01

275

Stimulation of Neurite Outgrowth Using an Electrically Conducting Polymer  

NASA Astrophysics Data System (ADS)

Damage to peripheral nerves often cannot be repaired by the juxtaposition of the severed nerve ends. Surgeons have typically used autologous nerve grafts, which have several drawbacks including the need for multiple surgical procedures and loss of function at the donor site. As an alternative, the use of nerve guidance channels to bridge the gap between severed nerve ends is being explored. In this paper, the electrically conductive polymer--oxidized polypyrrole (PP)--has been evaluated for use as a substrate to enhance nerve cell interactions in culture as a first step toward potentially using such polymers to stimulate in vivo nerve regeneration. Image analysis demonstrates that PC-12 cells and primary chicken sciatic nerve explants attached and extended neurites equally well on both PP films and tissue culture polystyrene in the absence of electrical stimulation. In contrast, PC-12 cells interacted poorly with indium tin oxide (ITO), poly(L-lactic acid) (PLA), and poly(lactic acid-coglycolic acid) surfaces. However, PC-12 cells cultured on PP films and subjected to an electrical stimulus through the film showed a significant increase in neurite lengths compared with ones that were not subjected to electrical stimulation through the film and tissue culture polystyrene controls. The median neurite length for PC-12 cells grown on PP and subjected to an electrical stimulus was 18.14 ? m (n = 5643) compared with 9.5 ? m (n = 4440) for controls. Furthermore, animal implantation studies reveal that PP invokes little adverse tissue response compared with poly(lactic acid-coglycolic acid).

Schmidt, Christine E.; Shastri, Venkatram R.; Vacanti, Joseph P.; Langer, Robert

1997-08-01

276

Electrical-Impedance Tomography for Opaque Multiphase Flows in Metallic (Electrically-Conducting) Vessels  

Microsoft Academic Search

A novel electrical-impedance tomography (EIT) diagnostic system, including hardware and software, has been developed and used to quantitatively measure material distributions in multiphase flows within electrically-conducting (i.e., industrially relevant or metal) vessels. The EIT system consists of energizing and measuring electronics and seven ring electrodes, which are equally spaced on a thin nonconducting rod that is inserted into the vessel.

SCOTT G. LITER; JOHN R. TORCZYNSKI; KIM A. SHOLLENBERGER; STEVEN L. CECCIO

2002-01-01

277

Electrical conduction in some sol-gel silicate glasses  

NASA Astrophysics Data System (ADS)

Measurements are reported for the electrical conductivity of different compositions of silicate glasses containing copper and vanadium in the temperature range 200-500 K. The experimental results for the two systems are found to be very similar and are analyzed with respect to theoretical models existing in the literature. At high temperatures, Mott's model of phonon-assisted small-polaron hopping between nearest neighbors is consistent with the data, while at low temperatures the variable-range-hopping model appears to be valid. The generalized polaron-hopping model of Schnakenberg and the percolation model applied to the small-polaron-hopping regime of Triberis and Friedman can also predict the temperature dependence of the conductivity data. The various model parameters obtained from the best fits are found to be consistent with the glass compositions.

Ghosh, A.; Chakravorty, D.

1993-08-01

278

Electrical conductivity of noble gases at high pressures  

SciTech Connect

Theoretical results for the electrical conductivity of noble gas plasmas are presented in comparison with experiment. The composition is determined within a partially ionized plasma model. The conductivity is then calculated using linear response theory, in which the relevant scattering mechanisms of electrons from ions, electrons, and neutral species are taken into account. In particular, the Ramsauer-Townsend effect in electron-neutral scattering is discussed and the importance of a correct description of the Coulomb logarithm in electron scattering by charged particles is shown. A detailed comparison with recent experiments on argon and xenon plasmas is given and results for helium and neon are also revisited. Excellent agreement between theory and experiment is observed, showing considerable improvement upon previous calculations.

Adams, J. R.; Reinholz, H.; Redmer, R.; Mintsev, V. B.; Shilkin, N. S.; Gryaznov, V. K. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany) and School of Physics, University of Western Australia, Crawley WA 6009 (Australia); Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Institute of Problems of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region (Russian Federation)

2007-09-15

279

Electrical conductivity of FeSi under pressure  

NASA Astrophysics Data System (ADS)

Chemical arguments suggest that FeSi can result from the reaction of the Fe-rich perovskite and post-perovskite in the D" layer with the Fe of the liquid core [1]. FeSi could thus accumulate in the lower parts of D", in particular the ultra-low velocity zones (ULVZ). Physical arguments (high density) and seismological arguments (low velocities) plead for its existence in these regions [2]. We compute the temperature-dependent electronic conductivity of FeSi from density-functional perturbation theory. From the phonons and electron-phonon coupling we solve the Boltzmann transport equations to the lowest order to give the electrical and thermal conductivities [3]. We find that the electrical resistivity of FeSi at lower mantle and outer core conditions is on the order of 3.5-4.0 micro Ohm m at 2500-3000K. This is about twice the resistivity of Fe in the same conditions, which is similar to the assumed resistivity of the outer core. If present in significant amounts, then the large values of the conductivity computed here suggest FeSi as the major conducting phase in the D" and ULVZ, and the mineral that would ensure the electromagnetic coupling between the mantle and the core. [1] E. Knittle and R. Jeanloz, Science, 251, 1438 (1991). [2] R. Caracas and R.M. Wentzcovitch, Geophys. Res. Lett. 31, No. 20, 10.1029/2004GL020601 (2004) [3] S.Y. Savrasov and D.Y. Savrasov, Phys. Rev. B, 54, 16487 (1996).

Verstraete, M.; Caracas, R.

2007-12-01

280

Apparent receptor-mediated activation of Ca2+-dependent conductive Cl- transport by shark-derived polyaminosterols.  

PubMed

The shark liver antimicrobial polyaminosterol squalamine is an angiogenesis inhibitor under clinical investigation as an anti-cancer agent and as a treatment for the choroidal neovascularization associated with macular degeneration of the retina. The related polyaminosterol MSI-1436 is an appetite suppressant that decreases systemic insulin resistance. However, the mechanisms of action of these polyaminosterols are unknown. We report effects of MSI-1436 on Xenopus oocytes consistent with the existence of a receptor for polyaminosterols. MSI-1436 activates bidirectional, trans-chloride-independent Cl- flux in Xenopus oocytes. At least part of this DIDS-sensitive Cl- flux is conductive, as measured using two-electrode voltage-clamp and on-cell patch-clamp techniques. MSI-1436 also elevates cytosolic Ca2+ concentration ([Ca2+]) and increases bidirectional 45Ca2+ flux. Activation of Cl- flux and elevation of cytosolic [Ca2+] by MSI-1436 both are accelerated by lowering bath Ca2+ and are not acutely inhibited by extracellular EGTA. Elevation of cytosolic [Ca2+] by MSI-1436 requires heparin-sensitive intracellular Ca2+ stores. Although injected EGTA abolishes the increased conductive Cl- flux, that Cl- flux is not dependent on heparin-sensitive stores. In low-bath Ca2+ conditions, several structurally related polyaminosterols act as strong agonists or weak agonists of conductive Cl- flux in oocytes. Weak agonist polyaminosterols antagonize the strong agonist, MSI-1436, but upon addition of the conductive Cl- transport inhibitor DIDS, they are converted into strong agonists. Together, these properties operationally define a polyaminosterol receptor at or near the surface of the Xenopus oocyte, provide an initial description of receptor signaling, and suggest routes toward further understanding of a novel class of appetite suppressants and angiogenesis inhibitors. PMID:16109810

Chernova, Marina N; Vandorpe, David H; Clark, Jeffrey S; Williams, Jon I; Zasloff, Michael A; Jiang, Lianwei; Alper, Seth L

2005-08-18

281

Electrical impedance tomography of complex conductivity distributions with noncircular boundary.  

PubMed

Electrical impedance tomography (EIT) uses low-frequency current and voltage measurements made on the boundary of a body to compute the conductivity distribution within the body. Since the permittivity distribution inside the body also contributes significantly to the measured voltages, the present reconstruction algorithm images complex conductivity distributions. A finite element model (FEM) is used to solve the forward problem, using a 6017-node mesh for a piecewise-linear potential distribution. The finite element solution using this mesh is compared with the analytical solution for a homogeneous field and a maximum error of 0.05% is observed in the voltage distribution. The boundary element method (BEM) is also used to generate the voltage data for inhomogeneous conductivity distributions inside regions with noncircular boundaries. An iterative reconstruction algorithm is described for approximating both the conductivity and permittivity distributions from this data. The results for an off-centered inhomogeneity showed a 35% improvement in contrast from that seen with only one iteration, for both the conductivity and the permittivity values. It is also shown that a significant improvement in images results from accurately modeling a noncircular boundary. Both static and difference images are distorted by assuming a circular boundary and the amount of distortion increases significantly as the boundary shape becomes more elliptical. For a homogeneous field in an elliptical body with axis ratio of 0.73, an image reconstructed assuming the boundary to be circular has an artifact at the center of the image with an error of 20%. This error increased to 37% when the axis ratio was 0.64. A reconstruction algorithm which used a mesh with the same axis ratio as the elliptical boundary reduced the error in the conductivity values to within 0.5% of the actual values. PMID:9353984

Jain, H; Isaacson, D; Edic, P M; Newell, J C

1997-11-01

282

Density, viscosity and electrical conductivity of protic alkanolammonium ionic liquids.  

PubMed

Ionic liquids are molten salts with melting temperatures below the boiling point of water, and their qualification for applications in potential industrial processes does depend on their fundamental physical properties such as density, viscosity and electrical conductivity. This study aims to investigate the structure-property relationship of 15 ILs that are primarily composed of alkanolammonium cations and organic acid anions. The influence of both the nature and number of alkanol substituents on the cation and the nature of the anion on the densities, viscosities and electrical conductivities at ambient and elevated temperatures are discussed. Walden rule plots are used to estimate the ionic nature of these ionic liquids, and comparison with other studies reveals that most of the investigated ionic liquids show Walden rule values similar to many non-protic ionic liquids containing imidazolium, pyrrolidinium, tetraalkylammonium, or tetraalkylphosphonium cations. Comparison of literature data reveals major disagreements in the reported properties for the investigated ionic liquids. A detailed analysis of the reported experimental procedures suggests that inappropriate drying methods can account for some of the discrepancies. Furthermore, an example for the improved presentation of experimental data in scientific literature is presented. PMID:21298175

Pinkert, André; Ang, Keng L; Marsh, Kenneth N; Pang, Shusheng

2011-02-07

283

Stationary cylindrical vortex in a viscous electrically conducting fluid  

NASA Astrophysics Data System (ADS)

An exact solution of the magnetohydrodynamic equations is constructed which describes steady vortex flow in a stationary cylinder on the axis of which a conductor carrying a known current is located. The solution is obtained under the assumption that the fluid is viscous and has finite electrical conductivity and that the magnetic field has only the axial and azimuthal components in a cylindrical coordinate system. It is found that the action of the Lorentz force is compensated by changing the pressure. Fluid flow occurs from the periphery to the axis of the cylinder under a pressure gradient, with flow rotation and swirling. The fluid flow causes a concentration of the magnetic lines near the axis of the cylinder, providing an exponential decrease in the magnetic field strength with distance from the axis. This flow can be considered as a model of a local increase in the magnetic field strength due to the transfer of its force lines by the flow of the electrically conducting fluid.

Baikin, A. N.; Golovin, S. V.

2013-07-01

284

Recyclable and electrically conducting carbon nanotube composite films  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT) composite films possess unique electrical, mechanical and thermal properties. In particular, some research has shown that CNT-polymer composite films greatly enhance the performance of organic light-emitting diodes. Therefore, CNT composite films have been intensively fabricated and applied. However, recent research has shown that CNTs carry carcinogenic risks in vivo. Therefore, how to collect and treat damaged or trashed CNT composite films are considerable tasks for scientists working in this area. From the viewpoint of environmental protection and saving resources, recycling the CNT composite films is the most efficient way to solve these problems. Here, we employ a benign water-soluble polymer, polyethyleneimine (PEI), to disperse CNTs and a general spin-coating process to prepare the homogeneous CNT composite films. The prepared CNT composite films exhibit good water-soluble properties and recyclability, i.e. they can be formed and dissolved in water. In addition, the long CNTs and high loading in the PEI matrix facilitates good electric conductivity in these CNT composite films. A significant improvement in the conductivity of the composite films is observed as the concentration of CNTs in the PEI increases, reaching as high as 43.73 S cm-1 when the CNT concentration is equal to 3%.

Zou, Guifu; Jain, Menka; Yang, Hao; Zhang, Yingying; Williams, Darrick; Jia, Quanxi

2010-03-01

285

Magnetoresistance, electrical conductivity, and Hall effect of glassy carbon  

SciTech Connect

These properties of glassy carbon heat treated for three hours between 1200 and 2700/sup 0/C were measured from 3 to 300/sup 0/K in magnetic fields up to 5 tesla. The magnetoresistance was generally negative and saturated with reciprocal temperature, but still increased as a function of magnetic field. The maximum negative magnetoresistance measured was 2.2% for 2700/sup 0/C material. Several models based on the negative magnetoresistance being proportional to the square of the magnetic moment were attempted; the best fit was obtained for the simplest model combining Curie and Pauli paramagnetism for heat treatments above 1600/sup 0/C. Positive magnetoresistance was found only in less than 1600/sup 0/C treated glassy carbon. The electrical conductivity, of the order of 200 (ohm-cm)/sup -1/ at room temperature, can be empirically written as sigma = A + Bexp(-CT/sup -1/4) - DT/sup -1/2. The Hall coefficient was independent of magnetic field, insensitive to temperature, but was a strong function of heat treatment temperature, crossing over from negative to positive at about 1700/sup 0/C and ranging from -0.048 to 0.126 cm/sup 3//coul. The idea of one-dimensional filaments in glassy carbon suggested by the electrical conductivity is compatible with the present consensus view of the microstructure.

Baker, D.F.

1983-02-01

286

EFFECTS OF TRITIUM GAS EXPOSURE ON ELECTRICALLY CONDUCTING POLYMERS  

SciTech Connect

Effects of beta (tritium) and gamma irradiation on the surface electrical conductivity of two types of conducting polymer films are documented to determine their potential use as a sensing and surveillance device for the tritium facility. It was shown that surface conductivity was significantly reduced by irradiation with both gamma and tritium gas. In order to compare the results from the two radiation sources, an approximate dose equivalence was calculated. The materials were also sensitive to small radiation doses (<10{sup 5} rad), showing that there is a measurable response to relatively small total doses of tritium gas. Spectroscopy was also used to confirm the mechanism by which this sensing device would operate in order to calibrate this sensor for potential use. It was determined that one material (polyaniline) was very sensitive to oxidation while the other material (PEDOT-PSS) was not. However, polyaniline provided the best response as a sensing material, and it is suggested that an oxygen-impermeable, radiation-transparent coating be applied to this material for future device prototype fabrication. A great deal of interest has developed in recent years in the area of conducting polymers due to the high levels of conductivity that can be achieved, some comparable to that of metals [Gerard 2002]. Additionally, the desirable physical and chemical properties of a polymer are retained and can be exploited for various applications, including light emitting diodes (LED), anti-static packaging, electronic coatings, and sensors. The electron transfer mechanism is generally accepted as one of electron 'hopping' through delocalized electrons in the conjugated backbone, although other mechanisms have been proposed based on the type of polymer and dopant [Inzelt 2000, Gerard 2002]. The conducting polymer polyaniline (PANi) is of particular interest because there are extensive studies on the modulation of the conductivity by changing either the oxidation state of the main backbone chain, or by protonation of the imine groups [de Acevedo, 1999]. There are several types of radiation sensors commercially available, including ionization chambers, geiger counters, proportional counters, scintillators and solid state detectors. Each type has advantages, although many of these sensors require expensive electronics for signal amplification, are large and bulky, have limited battery life or require expensive materials for fabrication. A radiation sensor constructed of a polymeric material could be flexible, light, and the geometry designed to suit the application. Very simple and inexpensive electronics would be necessary to measure the change in conductivity with exposure to radiation and provide an alarm system when a set change of conductivity occurs in the sensor that corresponds to a predetermined radiation dose having been absorbed by the polymer. The advantages of using a polymeric sensor of this type rather than those currently in use are the flexibility of sensor geometry and relatively low cost. It is anticipated that these sensors can be made small enough for glovebox applications or have the ability to monitor the air tritium levels in places where a traditional monitor cannot be placed. There have been a few studies on the changes in conductivity of polyaniline specifically for radiation detection [de Acevedo, 1999; Lima Pacheco, 2003], but there have been no reports on the effects of tritium (beta radiation) on conducting polymers, such as polyaniline or polythiophene. The direct implementation of conducting polymers as radiation sensor materials has not yet been commercialized due to differing responses with total dose, dose rate, etc. Some have reported a large increase in the surface conductivity with radiation dose while others report a marked decrease in conductive properties; these differing observations may reflect the competing mechanisms of chain scission and cross-linking. However, it is clear that the radiation dose effects on conducting polymers must be fully understood before these materials can be used

Kane, M.; Clark, E.; Lascola, R.

2009-12-16

287

Synthesis and applications of electrically conducting polymer nanocomposites  

NASA Astrophysics Data System (ADS)

This research focuses on the synthesis and applications of electrically conducting polymer nanocomposites through molecular self-assembly. Two different classes of polymers, polyaniline (PANI) and polyacetylenes have been synthesized by biomimetic catalysis and spontaneous polymerization method. For gas barrier materials, commercially available polymers, poly(allylamine hydrochloride) (PAH) and poly (acrylic acid) (PAA), have also been used and thermally cross-linked. The morphological, optical and electrical properties of amphiphilic polyacetylenes have been studied. Furthermore, barrier properties, permselectivity, pervaporation properties of polyacetylenes/aluminosilicate nanocomposites have been investigated. For processability and electrical properties of carbon nanotube and conducting polymers, substituted ionic polyacetylenes (SIPA) have been covalently incorporated onto single-walled carbon nanotubes (SWNT) using the "grafting-from" technique. In the first study, a nanocomposite film catalyst has been prepared by electrostatic layer-by-layer (ELBL) self-assembly of a polyelectrolyte and a biomimetic catalyst for synthesis of polyaniline. Poly(dimethyl diallylammonium chloride) (PDAC) and hematin have been used as polycation and counter anions, respectively. The absorption spectra by UV-vis-NIR spectroscopy showed that conductive form polyaniline was formed not only as a coating on the surface of the ELBL composites but was also formed in solution. Furthermore, it was found that the reaction rate was affected by pH and concentration of hematin in the multilayers. The feasibility of controlled desorption of hematin molecules from the LBL assembly was explored and demonstrated by changing the pH and hematin concentration. The polymerization rate of aniline in solution was enhanced with decreasing pH of the solutions due to increased desorption of hematin nanoparticles from the multilayers. These ELBL hematin assemblies demonstrated both a way to functionalize surfaces with conductive polyaniline and a potential method of reusability of the catalyst for improved cost effectiveness. For fabrication of multifunctional nanocomposite membranes, (P2EPy-R/Saponite) n on NafionRTM substrate was demonstrated by electrostatic layer-by layer assembly technique. (Abstract shortened by UMI.)

Ku, Bon-Cheol

288

Application of electrical and electromagnetic depth sounding in highly conductive sediments: The concept of vertical electrical anisotropy  

NASA Astrophysics Data System (ADS)

“Nördlinger Ries” is a meteorite crater in the Bavarian ‘Alb’ of Germany that was formed 15 million years ago, and subsequently filled with salty water. Evaporation resulted in an approximately 300 meter thick layer of young, highly conductive sediments. Audio-frequency Magnetotelluric (AMT) and geoelectric depth sounding (VES) techniques were used to analyze the electrical properties of these sediments. The apparent resistivities measured by the two methods are different, which can be explained by vertical electrical anisotropy (horizontal layering). Applying a joint forward modelling technique with resistivity variations found by a Monte Carlo method results in a best fit model containing a large number of layers, while separate inversions of the two data sets yield 3-layer models. Comparisons of the coefficient of anisotropy with drilling core samples demonstrate the reliability of the results. One difficulty of the AMT method is the low signal-to-noise ratio, because of the source’s deadband. Some suggestions for an “intelligent” processing are presented. Kerch (this session) is employing the result of the integrated conductivity as an input for 3D modelling of collected MT data.

Köhler, A.; Bahr, K.

2010-12-01

289

Electrical Conductivity and Dielectric Studies of Hydraulic Cements  

NASA Astrophysics Data System (ADS)

Electrical properties of portland cements and other non-portland cementitious materials have been studied at two different stages of hydration. The following relationships have been observed:. Higher water/cement (w/c) ratio (0.5 compared to 0.4) resulted in an increase of the relative permittivity and electrical conductivity of early stage hydrating materials. The relative permittivity values were close to 10('7). The phenomena giving rise to changes in electrical conductivity have been related to the heat of hydration. Higher alkali ion concentration resulted in higher electrical conductivity and relative permittivity values in cement pastes. Cations of inorganic admixtures were found to increase maximum peak of electrical conductivity and relative permittivity in the order: Ca('++) > Mg('++) > Sr('++) and K('+) (TURNEQ) Na('+) > Li('+). Dielectric properties of pressed hardened materials cured over water for 1 day with w/c = 0.20 and heat treated to 500(DEGREES)C prepared with type I, type III, and a microfine calcium silicate (MC500) cement have been compared as a function of temperature and frequency. The relative permittivity for type I hardened materials at 30(DEGREES)C was found to range from 12.5 to 9.4 at frequencies from 1 KHz to 2 MHz. The dissipation factor was found to range from 0.122 to 0.014. The relative permittivity and dissipation factors for type III hardened materials were found to range from 17.8 to 13.0 and from 0.035 to 0.071, respectively, and for MC500 hardened materials were determined to range from 7.6 to 6.9 and from 0.033 to 0.002, respectively. The activation energies determined from Arrhenius plots for the relaxation mechanism operating in these materials correspond to 0.33, 0.30, and 0.46 eV for type I, type III, and MC500 densified hardened materials, respectively. Cement/polymer composites have been prepared using 1.76 wt.% methyl cellulose polymer and a w/c ratio of 0.17. The relative permittivity and loss factor the samples cured over water range from 7.5 to 7.3 and from 0.001 to 0.005, respectively, at frequencies from 10 KHz to 1 MHz, while for the materials cured under sealed conditions, the values range from 5.6 to 5.4 and from 0.007 to 0.004. The heat-treated hardened MC500 cement based materials containing 60 vol.% silica microspheres have the lowest relative permittivity when compared to other materials prepared. The relative permittivity and loss factor of these materials ranged from 5.4 to 5.1 and from 0.035 to 0.012.

Pena, Marianela Perez

290

Electrical resistivity imaging of conductive plume dilution in fractured rock  

NASA Astrophysics Data System (ADS)

Electrical resistance tomography (ERT) was used to monitor a conductive plume dilution experiment that was conducted in fractured basalt in order to assess its applications in this type of fractured-rock environment. Tap water was injected into an injection well for 34 days to dilute a pre-existing potassium chloride (KCl) plume at a site in Idaho, USA. No further fluids were introduced artificially during a 62-day monitoring period. Both surface ERT and cross-borehole ERT were used to monitor dilution and displacement of the plume. A square grid of land-surface electrodes was used with the surface ERT. Three-dimensional images of surface ERT delineated areas of increased and decreased resistivities. Increasing resistivities are attributed to dilution/displacement of the KCl solution by tap-water invasion or the influx of seasonal recharge. Decreasing resistivities resulted from redistribution of residual KCl solution. Cross-borehole ERT was conducted between the injection well and each of seven surrounding monitoring wells. Polar plots of the injection-well resistivity data in the direction of each monitoring well delineate specific locations where tap water seeped from the injection well via preferential flow paths determined by time-dependent resistivity increases. Monitoring-well data indicate locations of clustered and isolated regions of resistivity changes.

Nimmer, Robin E.; Osiensky, James L.; Binley, Andrew M.; Sprenke, Kenneth F.; Williams, Barbara C.

2007-08-01

291

Reduction Kinetics and Electrical Conductivity in Lead Disilicate Glasses.  

NASA Astrophysics Data System (ADS)

Reduced lead silicate based glasses constitute the active element in night vision devices. The thermochemical reduction of these glasses is necessary to render them electronically conducting. In this thesis some of the more important reduction parameters and their influence on the post-reduction have been identified. The aim of this work was to establish the conduction mechanism(s) responsible in these glasses. The samples were reduced in hydrogen of varying moisture content, in the temperature range of 330-500 ^circC for various times. X-ray diffraction and thermogravimetric measurements clearly established that the reduction resulted in the formation of metallic lead islands with a diameter of ~4 nm, with an inter-island spacing of ~ 3.4 nm. In contrast to the electrical conductivity, the microstructure was found to be a weak function of reduction parameters. No coarsening of the microstructure was observed even after extended anneals at high temperatures, strongly suggesting that the final lead-island size was dictated by the size of the holes either present in the parent glass or formed as a result of reduction, in an otherwise rigid glass network. The electronic conductivity was found to go through a minimum with reduction temperature. Increasing the moisture content of the reducing gas resulted in an increase in the post-reduction resistance and in the sharpness of the minimum. The post-reduction activation energies were measured to be ~0.09 eV and found to be independent of all reduction variables, indicating that a single conduction mechanism was operative in all cases. The variation in conductivity was ascribed to variation in the number of mobile carriers. The mechanism of conduction was proposed to be that of a bipolaron hopping between Pb^{4+} and Pb ^{2+} ions, the former forming as a result of a disproportionation reaction that takes place during reduction and/or cooling of the samples from the reduction temperature. The electron transport is believed to take place by double valence fluctuation between the Pb^{4+} and Pb^{2+}, mediated by O _2^{2-} ions. The {[ Pb^{+2} ] over [ Pb^{+4 }] } ratio is believed to control the resistance of the reduced samples. The model qualitatively explains most of the observations made in this study.

Kumar, Sajal

292

Spectroscopic and Electrical Conductivity Studies of Some Semicarbazide Hydrochloride Complexes  

NASA Astrophysics Data System (ADS)

The infrared and electronic absorption spectra of semicarbazide hydrochloride and its complexes with anthracene, tetracyanoquinodimethane TCNQ, Na-fluorescein and cupferron were recorded in the regions 200-4000cm-1 and 200-400nm. The new bands that appeared in the complex spectra were assigned. The effect of the complex formation on the frequency and intensity of the active vibrational bands was also studied. The internal energy changes of the complexes were calculated in a new line of calculation to give a clear insight about the stability of the investigated complexes. The electrical conductivity of the complexes was measured in the temperature range 25-130°C. The activation energy E was calculated and discussed on the basis of the spectroscopic information.

Fadly, M.; El-Manakhly, H.

1998-11-01

293

Electrically Conductive and Optically Active Porous Silicon Nanowires  

PubMed Central

We report the synthesis of vertical silicon nanowire array through a two-step metal-assisted chemical etching of highly doped n-type silicon (100) wafers in a solution of hydrofluoric acid and hydrogen peroxide. The morphology of the as-grown silicon nanowires is tunable from solid nonporous nanowires, nonporous/nanoporous core/shell nanowires, and entirely nanoporous nanowires by controlling the hydrogen peroxide concentration in the etching solution. The porous silicon nanowires retain the single crystalline structure and crystallographic orientation of the starting silicon wafer, and are electrically conductive and optically active with visible photoluminescence. The combination of electronic and optical properties in the porous silicon nanowires may provide a platform for the novel optoelectronic devices for energy harvesting, conversion and biosensing.

Qu, Yongquan; Liao, Lei; Li, Yujing; Zhang, Hua; Huang, Yu; Duan, Xiangfeng

2009-01-01

294

Polymeric salt bridges for conducting electric current in microfluidic devices  

SciTech Connect

A "cast-in-place" monolithic microporous polymer salt bridge for conducting electrical current in microfluidic devices, and methods for manufacture thereof is disclosed. Polymeric salt bridges are formed in place in capillaries or microchannels. Formulations are prepared with monomer, suitable cross-linkers, solvent, and a thermal or radiation responsive initiator. The formulation is placed in a desired location and then suitable radiation such as UV light is used to polymerize the salt bridge within a desired structural location. Embodiments are provided wherein the polymeric salt bridges have sufficient porosity to allow ionic migration without bulk flow of solvents therethrough. The salt bridges form barriers that seal against fluid pressures in excess of 5000 pounds per square inch. The salt bridges can be formulated for carriage of suitable amperage at a desired voltage, and thus microfluidic devices using such salt bridges can be specifically constructed to meet selected analytical requirements.

Shepodd, Timothy J. (Livermore, CA); Tichenor, Mark S. (San Diego, CA); Artau, Alexander (Humacao, PR)

2009-11-17

295

High-Temperature Measurement of Seebeck Coefficient and Electrical Conductivity  

NASA Astrophysics Data System (ADS)

We have developed a system for simultaneous measurement of the electrical conductivity and Seebeck coefficient for thermoelectric samples in the temperature region of 300 K to 1000 K. The system features flexibility in sample dimensions and easy sample exchange. To verify the accuracy of the setup we have referenced our system against the NIST standard reference material 3451 and other setups and can show good agreement. The developed system has been used in the search for a possible high-temperature Seebeck standard material. FeSi2 emerges as a possible candidate, as this material combines properties typical of thermoelectric materials with large-scale fabrication, good spatial homogeneity, and thermal stability up to 1000 K.

de Boor, J.; Stiewe, C.; Ziolkowski, P.; Dasgupta, T.; Karpinski, G.; Lenz, E.; Edler, F.; Mueller, E.

2013-07-01

296

TIME DOMAIN REFLECTOMETRY CALIBRATION IN TERMS OF TRAVEL TIME, BULK ELECTRICAL CONDUCTIVITY, AND EFFECTIVE FREQUENCY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Many calibrations of conventional time domain reflectometry (TDR) have been done with the apparent electrical permittivity as the independent variable and water content as the dependent variable (or vice versa). Since the apparent permittivity is calculated as a function of the TDR pulse two-way tra...

297

Saline conducted electric coagulation (SCEC): original experience in experimental hepatectomy  

PubMed Central

Objective: To evaluate the feasibility and superiority of a new coagulating and hemostatic method named “saline conducted electric coagulation (SCEC)”. Methods: The Peng's multifunction operative dissector (PMOD) was modified to enable saline to effuse persistently out of its nib at a constant speed. In a group of six New Zealand rabbits, two hepatic lobes of each rabbits were resected respectively by SCEC and conventional electric coagulation (EC). The features of SCEC were recorded by photo and compared with conventional EC. After 7 d, the coagulating depth was measured in each residual hepatic lobe. Hepatic tissue was dyed by hematoxylin and eosin (HE) and studied under a microscope. Results: The coagulating depth increased with the continuation of SCEC time. Hepatectomies were performed successfully, no rabbit died in the perioperative period. The incisal surface of SCEC was gray-white with no red bleeding point. There was a thick solidified layer at the margin and a thin red-white intermittent layer between the solidified layer and normal hepatic tissue at the vertical section of SCEC. The mean coagulating depth of SCEC was 1.8 cm vs. 0.3 cm of conventional EC. Pathological examination showed a mild inflammatory reaction by SCEC. Conclusions: SCEC is a feasible and safe method for surgical hemostasis. As a new technique for liver resection, SCEC shows better coagulating effect and milder inflammatory reaction than conventional EC. Our study shows bloodless liver resection can also be performed by SCEC, especially for liver malignant tumor.

Ding, Guo-ping; Cao, Li-ping; Liu, Da-ren; Que, Ri-sheng

2012-01-01

298

Ventricular fibrillation risk estimation for conducted electrical weapons: critical convolutions.  

PubMed

The TASER® Conducted Electrical Weapon (CEW) is used by law enforcement agencies about 900 times per day worldwide and has been shown to reduce suspect and officer injuries by about 65%. However, since a CEW delivers rapid electrical pulses through injected probes, the risk of inducing ventricular fibrillation (VF) has been considered. Animal studies have shown that the tip of the probe must come within a few millimeters of the surface of the heart for the CEW to induce VF in a typical animal application. Early calculations of the CEW VF risk in humans used sophisticated 3-D chest models to determine the size of the probe landing areas that had cardiac tissue within a given distance of the inner surface of the ribs. This produced a distribution of area (cm(2)) vs. mm of depth. Echocardiography was then used to determine the shortest distance from the skin surface to the cardiac surface. This produced a population distribution of skin-to-heart (STH) distances. These 2 distributions were then convolved to arrive at a probability of inducing VF for a typical human CEW application. With 900, 000 probe-mode field uses to date, epidemiological results have shown that these initial VF risk estimates were significant overestimates. We present model refinements that take into account the gender and body-mass-index (BMI) of the target demographics and produce VF risk estimates concordant with the epidemiological results. The risk of VF is estimated at 0.4 per million uses with males. PMID:22254302

Kroll, Mark W; Lakkireddy, Dhanunjaya; Rahko, Peter S; Panescu, Dorin

2011-01-01

299

Initial results from the thermal and electrical conductivity probe (TECP) on Phoenix  

Microsoft Academic Search

The thermal and electrical conductivity probe (TECP), a component of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA), was included on the Phoenix Lander to conduct in situ measurements of the exchange of heat and water in the Martian polar terrain. TECP measured regolith thermal conductivity, heat capacity, temperature, electrical conductivity, and dielectric permittivity throughout the mission. A relative humidity sensor

Aaron P. Zent; Michael H. Hecht; Doug R. Cobos; Stephen E. Wood; Troy L. Hudson; Sarah M. Milkovich; Lauren P. DeFlores; Michael T. Mellon

2010-01-01

300

Estimating Dirichlet'S Integral and Electrical Conductance for Systems Which Are Not Self-Adjoint.  

National Technical Information Service (NTIS)

In simple electrical flow problems the Dirichlet integral of the potential function gives the electrical conductance. Moreover the Dirichlet integral of an arbitrary function satisfying the boundary condition gives an upper bound for the conductance. This...

R. J. Duffin

1968-01-01

301

Ion and temperature dependence of electrical conductance for natural waters  

SciTech Connect

Four empirical equations describing the temperature dependence of electrical conductance of aqueous solutions are compared for the case of single electrolytes. The best method uses a modified Walden product where the log of the ratio between the conductances at two temperatures is assumed to be proportional to the log of the corresponding ratio of viscosities, that is, log (X/sub t/sub 1///X/sub t/sub 2//) = K log (eta/sub t/sub 2///eta/sub t/sub 1//). A basis for predicting the constant of proportionality for mixed systems given the ion concentrations is proposed and the dependence of ionic strength effects and ion association is discussed. The value of K may also be estimated from the hydrogen ion concentration (in micromoles per liter) where K = 0.941 - 0.00639(H/sup +/) as found by regression of data for 692 lakes. A case study of time trend data for lakes is presented.

Sorensen, J.A.; Glass, G.E.

1987-07-01

302

DNA origami metallized site specifically to form electrically conductive nanowires.  

PubMed

DNA origami is a promising tool for use as a template in the design and fabrication of nanoscale structures. The ability to engineer selected staple strands on a DNA origami structure provides a high density of addressable locations across the structure. Here we report a method using site-specific attachment of gold nanoparticles to modified staple strands and subsequent metallization to fabricate conductive wires from DNA origami templates. We have modified DNA origami structures by lengthening each staple strand in select regions with a 10-base nucleotide sequence and have attached DNA-modified gold nanoparticles to the lengthened staple strands via complementary base-pairing. The high density of extended staple strands allowed the gold nanoparticles to pack tightly in the modified regions of the DNA origami, where the measured median gap size between neighboring particles was 4.1 nm. Gold metallization processes were optimized so that the attached gold nanoparticles grew until gaps between particles were filled and uniform continuous nanowires were formed. Finally, electron beam lithography was used to pattern electrodes in order to measure the electrical conductivity of metallized DNA origami, which showed an average resistance of 2.4 k? per metallized structure. PMID:22578334

Pearson, Anthony C; Liu, Jianfei; Pound, Elisabeth; Uprety, Bibek; Woolley, Adam T; Davis, Robert C; Harb, John N

2012-05-11

303

The effect of Holstein phonons on the electrical conductivity of doped monolayer graphene  

NASA Astrophysics Data System (ADS)

Electrical conductivity of graphene sheets is studied in the presence of coupling between lattice optical vibrations and electrons. Green's function approach is implemented to find the temperature behavior of electrical conductivity. Moreover, the effect of electronic doping on the electrical conductivity of graphene with electron-phonon interaction is investigated. Our results show that electrical conductivity increases as a function of temperature at low temperature and gets a maximum value and then decays at high temperature.

Rezania, Hamed

2013-12-01

304

Experimental and theoretical characterization of electrical contact in anisotropically conductive adhesive  

Microsoft Academic Search

Electrical conduction through anisotropically conductive adhesive (ACA) is caused by deformation of metal fillers under pressure and heat. In this work, the hardness of the electrical particles under various deformation degrees was determined by nano-indentor measurements and the electrical resistance of the electrical contacts was measured under various deformation degrees. Theoretical model and simulation have been developed for the microscopic

Ying Fu; Yanli Wang; Xitao Wang; Johan Liu; Zonghe Lai; Guoliang Chen; Magnus Willander

2000-01-01

305

Thermal and electrical conductivity of iron at Earth's core conditions.  

PubMed

The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles--unlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core. PMID:22495307

Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario

2012-04-11

306

D-H Interdiffusion Coefficients in Olivine: Implications for Electrical Conductivity in the Upper Mantle  

NASA Astrophysics Data System (ADS)

Knowledge about hydrogen diffusivity in mantle minerals is critical for understanding point defects and defect dominated processes such as creep and electrical conductivity. Hydrogen chemical diffusion coefficients have been used to constrain diffusivities of small polarons and Mg vacancies (Kohlstedt and Mackwell, 1998). Furthermore chemical diffusion coefficients have been used to calculate hydrogen contribution to electrical conductivity in olivine (Karato, 1990), however hydrogen self diffusion coefficients are more appropriate. In this study we use +{2}H as a traceable species of hydrogen to simulate the process of hydrogen self diffusion. Deuterium (+{2}H, sometimes referred to as D) was interdiffused into hydrogen (+{1}H) saturated, oriented, single crystal San Carlos olivine. We measured +{2}H and +{1}H profiles across samples from each of these experiments and fit interdiffusion coefficients (D_{D-H}). For olivine between 750-900 °C at 2 GPa we measured D_{D-H, [100]} = 10+{(-5.0 +/- 1.4)}*e+{(-135 +/- 30 kJ/mol)/(RT)} m+{2}/s. This value is 1 order of magnitude lower than D_{Exch, [100]}, the chemical diffusion coefficient for +{1}H based redox exchange in San Carlos olivine (Kohlstedt and Mackwell, 1998). Activation energies for D_{Exch, [100]} and D_{D-H, [100]} are very similar. We measured D_{D-H, [001]} = 10+{-12.0 +/- 0.2} m+{2}/s at 900 °C and 2 GPa; however only upper bound estimates for D_{D-H, [010]} and for D_{D-H, [001]} at lower temperatures could be determined with D_{D-H, [010]} D_{D-H, [001]} < 10+{-13} m+{2}/s. From comparison of D_{D-H} and D_{Exch} we calculate small polaron diffusion coefficients associated with redox exchange reactions (D_{h, [100]} = 10+{(-4.9 +/- 1.4)}*e+{(-135 +/- 30 kJ/mol)/(RT)} m+{2}/s) and confirm previous estimates of metal vacancy diffusion coefficients (D_{V(Me)} = D_{Incorp}/3). These +{2}H-+{1}H interdiffusion coefficients are used with the Nernst-Einstein relation to calculate electrical conductivity in hydrous olivine for comparison to experimental values. These calculations incorporate polaron and metal vacancy mobility estimates from anhydrous conductivity experiments. For 100 ppmw H_{2}O, 2 GPa and 900 °C, the calculated electrical conductivity by hydrogen is 0.7-2.4 log units lower and activation energy is 60% higher than reported electrical conductivity measurements (Wang et al., 2006; Yoshino et al., 2006; Yoshino et al., 2009, Poe et al., 2010). Thus current estimates of defect concentrations and mobilities from diffusion experiments and measured dry and wet electrical conductivities are not mutually consistent. The calculation presented here would require unrealistically high amounts of H_{2}O to account for high electrical conductivity anomalies measured at asthenosphere depths. However, the apparent differences in activation energy suggest that multiple types of hydrogen defects/species may occur and would need to be considered in the relationship between hydrogen diffusion and conduction in olivine.

Du Frane, W. L.; Tyburczy, J. A.; Sharp, T. G.

2010-12-01

307

Effect of Electric Field on Conductivity and Vickers Hardness of an Al-Li Alloy  

NASA Astrophysics Data System (ADS)

Static electric fields were applied on an aluminium-lithium alloy during solution treatment. The conductivity and Vickers hardness of the quenched Al-Li alloy is changed with the effect of electric field. The Vickers hardness increases with the applied electric field for a certain solutionizing time but decreases with the time under an electric field. In the absence of the electric field, the Vickers hardness and the conductivity increase synchronously, while reversed after electric field treatment. Positive and negative electric fields had the similar effect. The change of the local electron density in alloy caused by electric field is presented to explain the effect.

Liu, Bing; Chen, Da-Rong; Chen, Zheng; Wang, Yong-Xin; Li, Xiao-Ling

2003-11-01

308

Fracture criterion for conductive cracks in soda-lime glass under combined mechanical and electrical loading  

Microsoft Academic Search

Fracture tests of electrically conductive cracks on pre-notched four-point bending soda-lime glass samples were conducted\\u000a under combined mechanical and electrical loading. The experimental results show that the critical stress intensity factor\\u000a at fracture is reduced if an electric field is applied, thereby indicating that the electric field makes contributions to\\u000a the fracture of conductive cracks. Base on the charge-free zone

Dong-Jun Yan; Hai-You Huang; Chi-Wai Cheung; Tong-Yi Zhang

2010-01-01

309

Measurements of electrical conductivity of ceramics under electron irradiation in a high voltage electron microscope  

Microsoft Academic Search

A specimen holder for in-situ measurements of electrical conductivity in a high voltage electron microscope (HVEM) was developed. The performance of newly developed holder was checked by measuring the temperature dependence of the electrical conductivity in ZrO23mol%Y2O3 (YSZ) and the radiation induced conductivity was subsequently measured in YSZ, ?-Al2O3 and MgAl2O4 during irradiation with 1 MeV electrons. The electrical conductivity

Kenichi Shiiyama; Tadahiro Izu; Chiken Kinoshita; Masanori Kutsuwada

1996-01-01

310

Electrical conductivity and total dissolved solids in urine.  

PubMed

The objective of this paper is to study the relevance of electrical conductivity (EC) and total dissolved solids (TDS) in early morning and random samples of urine of urinary stone patients; 2,000 urine samples were studied. The two parameters were correlated with the extent of various urinary concrements. The early morning urine (EMU) and random samples of the patients who attended the urinary stone clinic were analysed routinely. The pH, specific gravity, EC, TDS, redox potential, albumin, sugar and microscopic study of the urinary sediments including red blood cells (RBC), pus cells (PC), crystals, namely calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD), uric acid (UA), and phosphates and epithelial cells were assessed. The extent of RBC, PC, COM, COD, UA and phosphates was correlated with EC and TDS. The values of EC ranged from 1.1 to 33.9 mS, the mean value being 21.5 mS. TDS ranged from 3,028 to 18,480 ppm, the mean value being 7,012 ppm. The TDS levels corresponded with EC of urine. Both values were significantly higher (P < 0.05) in the EMU samples than the random samples. There was a statistically significant correlation between the level of abnormality in the urinary deposits (r = +0.27, P < 0.05). In samples, where the TDS were more than 12,000 ppm, there were more crystals than those samples containing TDS less than 12,000 ppm. However, there were certain urine samples, where the TDS were over 12,000, which did not contain any urinary crystals. It is concluded that the value of TDS has relevance in the process of stone formation. PMID:19921168

Fazil Marickar, Y M

2009-11-17

311

High thermal conductivity connector having high electrical isolation  

DOEpatents

A method and article for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection. The connection method involves clamping, by thermal interference fit, an electrically isolating cylinder between an outer metallic ring and an inner metallic disk. The connection provides durable coupling of a heat sink and a heat source.

Nieman, Ralph C. (Downers Grove, IL); Gonczy, John D. (Oak Lawn, IL); Nicol, Thomas H. (St. Charles, IL)

1995-01-01

312

Influences of thickness and electrode materials on electrical conduction in polyethylene films  

Microsoft Academic Search

In this paper, influences of some factors on the electrical conduction in high-density polyethylene (HDPE) films are studied. HDPE samples with different thickness have been prepared. Their differences in DC electrical conduction are reported and discussed. It's found that the samples with different thickness have different DC conduction properties, the current density increases and then decreases with the increase of

Ninghua Wang; Yuanxiang Zhou; Xidong Liang; Zhicheng Guan

2003-01-01

313

Preparation and characterization of highly electrically and thermally conductive polymeric nanocomposites  

Microsoft Academic Search

The conducting polymers and polymeric composites have attracted considerable attention in recent years because of their potential applications in advanced technologies, for example, in antistatic coatings, electromagnetic shielding. The introduction of electrically conductive fillers such as graphite, carbon black, metal and metal oxide powders into the polymeric matrix is a promising approach to fabricate electrically conductive polymeric materials. The recent

Volkan Çeçen; I. Özdemir; Alparslan Turgut; Igor Krupa; Maria Omastova; Igor Novak

314

Electrical conductivity of fluidized bed electrodes: its significance and some experimental measurements  

Microsoft Academic Search

By applying a mathematical model (developed by Newman and Tobias for porous electrodes) to a fluidized bed electrode it can be concluded that the effective electrical conductivity of the bed is a key parameter affecting bed performance. Poor current and power efficiencies and operational difficulties are predicted for beds with low electrical conductivities and it is suggested that high conductivities

B. J. Sabacky; J. W. Evans

1978-01-01

315

The electrical conductivity of fluidized bed electrodes---its significance and some experimental measurements  

Microsoft Academic Search

By applying a mathematical model (developed by Newman and Tobias for porous electrodes) to a fluidized bed electrode it can be concluded that the effective electrical conductivity of the bed is a key parameter affecting bed performance. Poor current and power efficiencies and operational difficulties are predicted for beds with low electrical conductivities and it is suggested that high conductivities

B. J. Sabacky; J. W. Evans

1977-01-01

316

Laboratory measurements of electrical conductivities of hydrous and dry Mount Vesuvius melts under pressure  

Microsoft Academic Search

Quantitative interpretation of MT anomalies in volcanic regions requires laboratory measurements of electrical conductivities of natural magma compositions. The electrical conductivities of three lava compositions from Mount Vesuvius (Italy) have been measured using an impedance spectrometer. Experiments were conducted on both glasses and melts between 400 and 1300°C, at both ambient pressure in air and high pressures (up to 400

A. Pommier; F. Gaillard; M. Pichavant; B. Scaillet

2008-01-01

317

Recent Developments in Mixed Ionic and Electronic Conducting Electrodes for the Alkali Metal Thermal Electric Converter (AMTEC)  

NASA Astrophysics Data System (ADS)

Mixed ionic and electronic conducting electrodes (MIECEs) have recently gained more attention in the development of the Alkali Metal Thermal Electric Converter (AMTEC). The advantage of MIECEs, as their name implies, is that they allow both electronic transport and ionic transport within the matrix of their materials. This lowers charge transport resistances, which lowers overall electrical resistances of the electrochemical system, and, thus, can improve reaction rates for a given apparent or superficial surface area of the electrode. The AMTEC system is a self-contained, self-regenerating compact technology that electrochemically converts heat directly to electricity. Our latest developments for AMTEC MIECEs are presented. These include electrodes formulated from various blends of titanium nitride or molybdenum with titanium dioxide. The general formulation, application, processing and testing methods for these electrodes are presented. Measured power densities of selected MIECEs are given. The physical morphology, and composition of our MIECEs are also described. Finally, a possible operational mechanism for these electrodes is proposed.

Fletcher, Robert W.; Schwank, Johannes W.

2003-01-01

318

Studies of electrical conduction in pyroelectric DTGS: PVDF composites  

NASA Astrophysics Data System (ADS)

The AC and DC conductivities of pyroelectric composite, deuterated triglycine sulfate (DTGS): polyvinylidene fluoride (PVDF) having 15%, 20%, and 40% DTGS content (by weight) have been measured at temperature ranging from room temperature to 55 °C. The ac conductivity of composites at 1 MHz shows very weak temperature dependence. The dc conductivity for 20% and 40% DTGS content (by weight) composites shows activated behavior.

Batra, Ashok K.; Simmons, M.; Guggilla, Padmaja; Aggarwal, M. D.; Lal, R. B.

2004-06-01

319

Protonic conduction in oxide glasses: Simple relations between electrical conductivity, activation energy, and the OH bonding state  

Microsoft Academic Search

Simple relations between protonic conductivity (sigma) and the peak wave number (nuOH) of O-H infrared absorption band, and between activation energy for the electrical conduction and the wave number (nuOH) were found in oxide glasses containing no alkali- and\\/or transition-metal ions. The present investigation enables one to evaluate the protonic conductivity and the activation energy at a unit proton concentration

Yoshihiro Abe; Hideo Hosono; Yoshio Ohta; L. L. Hench

1988-01-01

320

Electrical conductivity of hydrous mantle minerals, with implications for the conductivity structure of the mantle transition zone  

NASA Astrophysics Data System (ADS)

Water plays an important role in the electrical conductivity of the mantle transition zone. For example, high conductivity values were observed in the mantle transition zone beneath the Philippine Sea. Recent laboratory electrical conductivity measurements focused on wadsleyite and ringwoodite. However, it is difficult to explain high conductivity in the transition zone, although proton conduction in these minerals can enhance the conductivity. Most of water was transported into the mantle by hydrous minerals with descending slab. Some dense hydrous magnesium silicates (DHMS) can be stable in the descending slab (e.g. super hydrous phase B and phase D), which are expected to exhibit high conductivity due to the high water content in the crystal structure. However, the contribution of DHMS to the electrical conductivity has not been investigated. Here we report the electrical conductivities of brucite, phase A and super hydrous phase B under high pressure condition and the pressure effect on the conductivity of brucite. The electrical conductivity of brucite, phase A and super hydrous phase B (suB) ploycrystals, were measured by means of impedance spectroscopy in the frequency range 10-2-106 Hz at pressures of 3 GPa, 10 GPa and 18 GPa, respectively, and in the temperature range of 500-775 K. The increase of electrical conductivity with temperature follows the Arrhenian formula: ? =?0exp(-?H/kT). The pre-exponential factors and activation enthalpies of brucite, phase A and suB yield values of 149.7 S/m and 0.90 eV, 4.88 S/m and 0.74 eV, 292 S/m and 0.83 eV, respectively. The electrical conductivities of brucite (water content of 30.9 wt.%) at 3 GPa was about one order lower of magnitude compared with those of suB (water content of 5.8 wt.%) at 18 GPa, and slightly higher than those of phase A at 10 GPa (water content of 11.9 wt.%) in the measured temperature range. For brucite, effect of pressure on the electrical conductivity was also investigated in the pressure range of 2.2-14.4 GPa. Electrical conductivity of brucite polycrystals was enhanced around one order of magnitude with increasing pressure from 2.2 GPa to 14.4 GPa. The pre-exponential factor, activation energy and the activation volume were determined to be 55 S/m, 0.45 eV and -0.35 cm3/mol. If we extrapolate the results of suB to a condition of 18 GPa and 1500 K (within the stability field of suB, but much lower than the normal mantle geotherm), the conductivity is 5X10-1 S/m, which is higher than currently available 1-D conductivity-depth profiles obtained from geoelectromagnetic studies (Kuvshinov et al., 2005). If the dense hydrous magnesium silicates have the negative activation volume as well as brucite, the electrical conductivity of super hydrous phase B, phase E and phase D at higher pressure would become higher. The high conductivity of the cold mantle transition zone, such as stagnant slab, can be well explained by the presence of dense hydrous magnesium silicate.

Guo, X.; Yoshino, T.

2011-12-01

321

Origin of High Electrical Conductivity in the Lower Continental Crust: A Review  

Microsoft Academic Search

Electromagnetic measurements have demonstrated that the lower continental crust has remarkable electrical anomalies of high conductivity and electrical anisotropy on a global scale (probably with some local exceptions), but their origin is a long-standing and controversial problem. Typical electrical properties of the lower continental crust include: (1) the electrical conductivity is usually 10-4 to 10-1 S\\/m; (2) the overlying shallow

Xiaozhi Yang

2011-01-01

322

Electrical conductivity of high-strength Cu-Nb microcomposites  

SciTech Connect

The conductivity of Cu-Nb microcomposites was studied as a function of the composition and the parameters of the microstructure varying with the degree of deformation. The effect of heat treatment on conductivity of Cu and composites is also considered. The conductivity of Cu-Nb composites with the reduction in area lnA{sub 0}/A < 4.9 is well described by the Landauer formula allowing for conductivity and the volume fraction of the components. The influence of the principal scattering mechanisms on conductivity of Cu in the composite is treated on the grounds of the experimental results obtained in this work and the analysis of the literary data. The linear correlation between strength and conductivity is obtained for the specimens heat treated at temperatures up to 600 C. This correlation is violated, however, for the specimens subjected to heat treatment at temperatures above 600 C.

Kozlenkova, N.I.; Pantsyrnyi, V.I.; Nikulin, A.D.; Shikov, A.K.; Potapenko, I.I. [A.A. Bochvar All-Russia Inst. of Inorganic Materials, Moscow (Russian Federation)

1996-07-01

323

Constraints on Mantle Electrical Conductivity from Field and Laboratory Measurements  

Microsoft Academic Search

both in terms of magnitude and distribution of data residuals. Smooth models in the sense of minimum first and second derivatives of log(conductivity) with log(depth) show conductivities increasing from 0.01 S\\/m 200 km deep to 2 S\\/m at a depth of 2000 km. Geotherms inferred from these conductivities using a laboratory model for the temperature dependence of dry sub- solidus

Steven Constable

1993-01-01

324

Electrical conductivity of polyvinyl alcohol-multiwall carbon nanotubes composites  

NASA Astrophysics Data System (ADS)

The dc and ac conductivity of polyvinyl alcohol (PVA)-multiwalled carbon nanotube (MWNT) nanocomposites prepared by solution casting were investigated by employing dielectric relaxation spectroscopy in broad frequency range (0.1 Hz-10 MHz) at room temperature as a function of the conductive weight fraction (p) ranging from 0 to 2wt.%. The frequency dependence of the measured conductivity obeys the universal dynamic response (UDR); a dc plateau followed, by the power law above a critical frequency (fc).

Amrin, Sayed; Deshpande, V. D.

2013-06-01

325

Electrical Transport in Semiconductor Nanoparticle Arrays: Conductivity, Sensing and Modeling  

NASA Astrophysics Data System (ADS)

Electrical properties of nanoparticle ensembles are dominated by interparticle transport processes, mainly due to particle-particle and particle-contact interactions. This makes their electrical properties dependent on the network properties such as porosity and particle size and is a main prerequisite for solid- state gas sensors, as the surrounding gas atmosphere influences the depletion layer surrounding each particle. Different kinds of nanoparticle arrays such as pressed pellets, printed layer, and thin films prepared by molecular beam-assisted deposition are characterized with respect to their electrical transport properties. Experimental results are shown for the electrical and sensing properties of several metal oxide nanoparticle ensembles and the influence of porosity is investigated during compaction of nanoparticle powders exposed to an external force. A model describing these properties is developed and it is shown that for a given material only porosity, geometry, and particle size influence the overall electrical properties. The model developed for the description of current transport in particulate matter can also be utilized to describe current-assisted sintering.

Hartner, Sonja; Schwesig, Dominik; Plümel, Ingo; Wolf, Dietrich E.; Lorke, Axel; Wiggers, Hartmut

326

Temperature and Structure of the Moon According to Electrical Conductivity Data on Its Interior.  

National Technical Information Service (NTIS)

Based on the familiar temperature dependence of conductivity, which relates electrical conductivity to parameters characterizing the petrological composition of rocks, a temperature estimate of the lunar interior was obtained: the temperature within the m...

A. Okulesskiy

1975-01-01

327

Water Chemistry and Electrical Conductivity Database for Rivers in Yellowstone National Park, Wyoming.  

National Technical Information Service (NTIS)

This study aims to quantify relations between solute concentrations (especially chloride) and electrical conductivity for several rivers in Yellowstone National Park (YNP), by using automated samplers and conductivity meters. Norton and Friedman (1985) fo...

H. P. Heasler J. B. Lownestern L. E. Clor M. A. Huebner R. B. McCleaskey

2012-01-01

328

Preparation of Electrically Conductive Polystyrene/Carbon Nanofiber Nanocomposite Films  

ERIC Educational Resources Information Center

|A simple and effective approach to prepare conductive polystyrene/carbon nanofiber (PS/CNF) nanocomposite films via a solution dispersion method is presented. Inexpensive CNF, which has a structure similar to multi-walled carbon nanotubes, is chosen as a nanofiller in this experiment to achieve conductivity in PS films. A good dispersion is…

Sun, Luyi; O'Reilly, Jonathan Y.; Tien, Chi-Wei; Sue, Hung-Jue

2008-01-01

329

Measurements of the Electrical Conductivities of Air over Hot Water  

Microsoft Academic Search

Measurements of the conduction current between two electrodes in air over recently boiled water have been interpreted by Carlon as indicating that the humidified air became highly conductive and that large numbers of ions were produced in the air after it was saturated with water vapor. These interpretations have been questioned because it is possible that the insulators used in

C. B. Moore; B. Vonnegut

1988-01-01

330

Electric conductance of metal nanowires at mechanically controllable break junctions under electrochemical potential control  

Microsoft Academic Search

We have developed the mechanically controllable break junction setup with an electrochemical cell (EC–MCBJ) to measure the electric conductance of metal nanowires under electrochemical potential control. The electric conductance of Au nanowires was investigated in 0.1M Na2SO4 solution using EC–MCBJ. The conductance of the Au nanowires was quantized in units of G0 (=2e2\\/h), showing clear features in the conductance histogram.

Manabu Kiguchi; Nobuo Sekiguchi; Kei Murakoshi

2007-01-01

331

Different clinical electrodes achieve similar electrical nerve conduction block.  

PubMed

Objective. We aim to evaluate the suitability of four electrodes previously used in clinical experiments for peripheral nerve electrical block applications. Approach. We evaluated peripheral nerve electrical block using three such clinical nerve cuff electrodes (the Huntington helix, the Case self-sizing Spiral and the flat interface nerve electrode) and one clinical intramuscular electrode (the Memberg electrode) in five cats. Amplitude thresholds for the block using 12 or 25 kHz voltage-controlled stimulation, onset response, and stimulation thresholds before and after block testing were determined. Main results. Complete nerve block was achieved reliably and the onset response to blocking stimulation was similar for all electrodes. Amplitude thresholds for the block were lowest for the Case Spiral electrode (4 ± 1 Vpp) and lower for the nerve cuff electrodes (7 ± 3 Vpp) than for the intramuscular electrode (26 ± 10 Vpp). A minor elevation in stimulation threshold and reduction in stimulus-evoked urethral pressure was observed during testing, but the effect was temporary and did not vary between electrodes. Significance. Multiple clinical electrodes appear suitable for neuroprostheses using peripheral nerve electrical block. The freedom to choose electrodes based on secondary criteria such as ease of implantation or cost should ease translation of electrical nerve block to clinical practice. PMID:23986089

Boger, Adam; Bhadra, Narendra; Gustafson, Kenneth J

2013-08-28

332

Magnetic susceptibility and electrical conductivity of the highest chromium germanide  

Microsoft Academic Search

Results are given of measurements over the temperature range 80 1000 ° K of the magnetic susceptibility (chi) and the electrical resistivity (varrho) of the highest chromium germanide Cr11Ge19. A ferromagnetic spin ordering is indicated at T < 86 ° K. From the varrho(T) dependence and the values of the resistivity, thermo-emf and Hall constant, it is concluded that the

V. L. Zagryazhskii; P. V. Gel'D; A. K. Shtol'Ts

1968-01-01

333

Magnetic susceptibility and electrical conductivity of the highest chromium germanide  

Microsoft Academic Search

Results are given of measurements over the temperature range 80–1000 ° K of the magnetic susceptibility (?) and the electrical resistivity (?) of the highest chromium germanide Cr11Ge19. A ferromagnetic spin ordering is indicated at T < 86 ° K. From the ?(T) dependence and the values of the resistivity, thermo-emf and Hall constant, it is concluded that the compound

V. L. Zagryazhskii; P. V. Gel'd; A. K. Shtol'ts

1968-01-01

334

Different clinical electrodes achieve similar electrical nerve conduction block  

NASA Astrophysics Data System (ADS)

Objective. We aim to evaluate the suitability of four electrodes previously used in clinical experiments for peripheral nerve electrical block applications. Approach. We evaluated peripheral nerve electrical block using three such clinical nerve cuff electrodes (the Huntington helix, the Case self-sizing Spiral and the flat interface nerve electrode) and one clinical intramuscular electrode (the Memberg electrode) in five cats. Amplitude thresholds for the block using 12 or 25 kHz voltage-controlled stimulation, onset response, and stimulation thresholds before and after block testing were determined. Main results. Complete nerve block was achieved reliably and the onset response to blocking stimulation was similar for all electrodes. Amplitude thresholds for the block were lowest for the Case Spiral electrode (4 ± 1 Vpp) and lower for the nerve cuff electrodes (7 ± 3 Vpp) than for the intramuscular electrode (26 ± 10 Vpp). A minor elevation in stimulation threshold and reduction in stimulus-evoked urethral pressure was observed during testing, but the effect was temporary and did not vary between electrodes. Significance. Multiple clinical electrodes appear suitable for neuroprostheses using peripheral nerve electrical block. The freedom to choose electrodes based on secondary criteria such as ease of implantation or cost should ease translation of electrical nerve block to clinical practice.

Boger, Adam; Bhadra, Narendra; Gustafson, Kenneth J.

2013-10-01

335

Variational theory of electrical conductivity and kinetic tearing modes  

Microsoft Academic Search

A variational theory for Ohm's law is presented, which is valid for arbitrary collision frequency for a slab geometry using a pitch angle scattering collision operator, and includes the effects of a spatial inhomogeneity and temperature gradients. The theory is a generalization of the work of Hazeltine et al. (1975) to include the effects of magnetic shear in the electrical

C. S. Chang; R. R. Dominguez; R. D. Hazeltine

1981-01-01

336

Synthesis of Electrically Conducting Polymers Synthese Elektrisch Leitfaehiger Polymerer.  

National Technical Information Service (NTIS)

The most important publications with the exception of the patents in the intensively researched field of the synthesis of aliphatic and aromatic polymers with pi electron conjugation as well as their doping to highly conducting materials are presented. Fo...

H. Naarmann

1982-01-01

337

Probing electrical conduction behavior of BaSnO3  

Microsoft Academic Search

The ac conductivity, sigmaac of BaSnO3 has been measured in the temperature range 310-520 K and frequency range 100 Hz-1 MHz. Below 420 K the conductivity is almost independent of temperature while between 420 and 520 K it is temperature dependent. At 100 kHz the activation energy of these two regions is 0.08 and 0.35 eV, respectively. It has been

Shail Upadhyay; Ashok Kumar Sahu; Devendra Kumar; Om Parkash

1998-01-01

338

Electrical conductivity and dielectric properties of sulfamic acid doped polyaniline  

Microsoft Academic Search

The temperature and frequency dependence of dielectric constant (??) and dielectric loss (??) is studied for different samples of polyaniline (PANI), doped with different concentration of sulfamic acid in the frequency range (10–100kHz) and temperature range (300–400K). The dc conductivity has also been measured to see the effect of sulfamic acid and the conduction mechanism has been explained by the

Sadia Ameen; Vazid Ali; M. Zulfequar; M. Mazharul Haq; M. Husain

2007-01-01

339

Dielectric properties and electrical conduction in yttrium iron garnet (YIG)  

Microsoft Academic Search

The dielectric properties (dielectric constant and loss) of a single crystal of yttrium iron garnet (Y3Fe5O12) were measured in the temperature range 77–725 K and in the frequency range 100 Hz-1 MHz. AC conductivity was derived from\\u000a dielectric constant and loss. DC conductivity was measured in the temperature range 30–725 K. Thermoelectric power (TEP) was\\u000a measured from 77–800 K. On

Lalitha Sirdeshmukh; K Krishna Kumar; S Bal Laxman; A Rama Krishna; G Sathaiah

1998-01-01

340

Physical property and electrical conductivity of electroless Ag-plated carbon fiber-reinforced paper  

Microsoft Academic Search

The addition of a large amount of conductive filler to paper in order to increase electrical conductivity adversely affects some physical properties of the paper. Hence, it is desirable that conductive paper can be manufactured by adding only a small amount of conductive filler. Reinforced paper was manufactured by adding (1) electroless Ag-plated carbon fiber or (2) activated carbon fiber

Joon Jang; Seung Kon Ryu

2006-01-01

341

Mapping a 3-D conductivity anomaly using a vertical electric source: Field results  

Microsoft Academic Search

A method for monitoring an enhanced oil recovery (EOR) process is the mapping of electrical conductivity changes due to injection of steam or other fluids. Since the conductivity change will be three-dimensional (3-D) in character, it is necessary to develop techniques to map 3-D conductivity distributions. At the Richmond test site, near Berkeley California, we conducted a field experiment to

L. C. Bartel; G. A. Newman

1991-01-01

342

THE ELECTRICAL CONDUCTIVITY OF SOLUTIONS OF ALKALI METALS IN THEIR MOLTEN HALIDES  

Microsoft Academic Search

The electrical conductivity of alkali metal solutions in their molten ; halides has been measured by means of a synthetic sapphire conductance cell. The ; specific conductance increases with increasing metal concentration. The ; equivalent conductance of K, A K, in both KCl and KBr also increases, namely, ; from 2800 ohm⁻¹ cm² (K--KCl, 820 deg ), 6100 (K--KBr, 760

H. R. Bronstein; M. A. Bredig

1958-01-01

343

The high-temperature electrical conductivity of a model catalyst containing conducting and insulating oxides  

Microsoft Academic Search

DC conductivity of catalysts comprising insulating high-alumina cement and semi-metallic Fe3O4 was studied between 300 and 800K in an inert atmosphere. The activation energy of the thermally promoted conductivity decreased rapidly with increasing content of the conducting component. The high-temperature activation energy falls exponentially with increasing Fe3O4 content between about 0.1 and 0.7 volume fraction, approaching the value for pure

A. Ovenston; J. R. Walls

1985-01-01

344

Measurements of the Electrical Conductivities of Air over Hot Water.  

NASA Astrophysics Data System (ADS)

Measurements of the conduction current between two electrodes in air over recently boiled water have been interpreted by Carlon as indicating that the humidified air became highly conductive and that large numbers of ions were produced in the air after it was saturated with water vapor. These interpretations have been questioned because it is possible that the insulators used in the high-humidity experiments allowed leakage currents to flow and these were treated as though they were conduction currents through the air.We repeated these measurements with the use of a conventional, Gerdien cylinder conductivity-measuring apparatus that had insulators heated to temperatures above the dew point of the water vapor in the air being measured so that the insulators maintained high resistances. The results from the heated Gerdien cylinder experiments contradict the suggestions of high conductivities in humid air, for the measured conductivities of air were repeatedly observed to decrease by about 50% when recently boiled, hot water was brought in contact with the air.

Moore, C. B.; Vonnegut, B.

1988-03-01

345

ELECTRICAL CONDUCTIVITY SPECTRA OF SMECTITES AS INFLUENCED BY SATURATING CATION AND HUMIDITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Electrical conductivity is an important soil property related to salinity, and is often used for delineating other soil properties. The purpose of this study was to examine the influence of smectite properties on the complex electrical conductivity spectra of hydrated smectites. Four reference smect...

346

Measurement of soil water content and electrical conductivity by time domain reflectometry: a review  

Microsoft Academic Search

Non-destructive measurement of soil water content and electrical conductivity has been desired for many years. Recent development of time domain reflectometry (TDR) enables us to simultaneously obtain soil water content and electrical conductivity using a single probe with a minimal disturbance of soil. Research on water and solute transport in porous media using TDR has flourished in the last few

K. Noborio

2001-01-01

347

Design of electrically and thermally conductive polymer composites for electronic packaging  

Microsoft Academic Search

In designing electrically and thermally conductive polymer composites, one must know the fundamental knowledge of their macroproperty-microstructure relations. The macroproperties of interest in this study are the effective electrical and thermal conductivities. The key microstructural factors include filler shape, size, size distribution and geometric arrangement of fillers. The main tasks consist of processing, characterization and analytical modeling of silver flake\\/polymer

Woo-Jin Kim

1998-01-01

348

Dynamic and quantitative exploration on technology evolution mechanism: The case of electrical conducting polymer nanocomposite  

Microsoft Academic Search

This study aims to obtain global overview on electrical conducting polymer nanocomposite development along time horizon as well as to obtain dynamic and quantitative exploration on technology evolution mechanism, a total of 1421 electrical conducting polymer related nanocomposite patents are retrieved from USPTO patent database and patent citation network is generated by combing both patent citation and social network analysis.

Hsin-Ning Su; Pei-Chun Lee

2009-01-01

349

Measurement of the Electrical Conductivity and Dielectric Constant without Contacting Electrodes  

Microsoft Academic Search

A method is developed whereby electrical conductivity and dielectric constant of semiconducting and dielectric materials without contacting electrodes can be measured. The principle of this method is that a specimen suspended in a rotating field with a fine fiber is rotated by the torque proportional to the electrical conductivity or the imaginary part of its complex dielectric constant, and the

Tomoya Ogawa

1961-01-01

350

Spatial and Temporal Variations in Electrical Conductivity in North Mississippi Loamy Soils  

Microsoft Academic Search

The use of electromagnetic induction (EM) to characterize and quantify spatial and temporal variations in soil properties is appealing due to low operational costs, rapid measurements, and device mobility. EM methods are sensitive to soil electrical conductivity, which can vary with soil moisture, clay content, soil salinity, and the presence of electrically conductive minerals. We are evaluating the controls on

M. S. Aufman; R. M. Holt

2005-01-01

351

Electrical and thermal conductivity of A319 and A356 aluminum alloys  

Microsoft Academic Search

A rotational contactless inductive measurement technique has been used to measure the electrical resistivity of A319 and A356 aluminum alloys at both solid and liquid states. The method is based on the phenomena that when a conducting material rotates in a magnetic field, circulating eddy currents are induced and generate an opposing torque, which is proportional to the electrical conductivity

S. I. Bakhtiyarov; R. A. Overfelt; S. G. Teodorescu

2001-01-01

352

Electrical Conductivity and Anisotropy in Pacific Lithosphere: CSEM Results from APPLE  

Microsoft Academic Search

Emplacement of the sheeted dyke complex and strain associated with plate formation at mid-ocean ridge spreading centers may influence electrical conductivity at various depths in the lithosphere, and may leave an anisotropic fabric frozen in place. By measuring lithospheric electrical conductivity and anisotropy as a function of depth, insight may be gained regarding the formation and evolution of oceanic crust

J. Behrens; S. Constable; L. MacGregor; M. Everett

2002-01-01

353

Electrical Conductivity and Anisotropy in Pacific Lithosphere: CSEM Results from APPLE  

Microsoft Academic Search

Strain associated with plate formation at mid-ocean ridge spreading centers may influence electrical conductivity at various depths in the lithosphere, and may leave an anisotropic fabric frozen in place. By measuring lithospheric electrical conductivity and anisotropy, insight may be gained regarding the formation and evolution of oceanic crust and mantle. Controlled-source electromagnetic (CSEM) sounding of 35 Ma Pacific lithosphere was

J. Behrens; S. Constable; M. Everett; L. MacGregor

2003-01-01

354

Electrical conductivity of thermoresponsive shape-memory polymer with embedded micron sized Ni powder chains  

Microsoft Academic Search

The electrical resistivity of a thermoresponsive polyurethane shape-memory polymer (SMP) filled with micron sized Ni powders is investigated in this letter. We show that, by forming conductive Ni chains under a weak static magnetic field (0.03 T), the electrical conductivity of the SMP composite in the chain direction can be improved significantly, which makes it more suitable for Joule heat

J. S. Leng; X. Lan; Y. J. Liu; S. Y. Du; W. M. Huang; N. Liu; S. J. Phee; Q. Yuan

2008-01-01

355

Dominant role of tunneling resistance in the electrical conductivity of carbon nanotube-based composites  

Microsoft Academic Search

The effect of nanotube\\/nanotube contact resistance on the electrical conductivity of carbon nanotube-based nanocomposites is studied. The tunneling resistance due to an insulating film of matrix material between crossing nanotubes is calculated by assuming a rectangular potential barrier in the insulating film. Monte Carlo simulations indicate that the tunneling resistance plays a dominant role in the electrical conductivity of composites,

Chunyu Li; Erik T. Thostenson; Tsu-Wei Chou

2007-01-01

356

Electrical Conductivity of Solid Oxides. Xi. La2O3-CaO System.  

National Technical Information Service (NTIS)

In view of the previously investigated electrical conductivity of a solid solution with the fluorite-type lattice, the subject of this study was to determine the effect of the change of the crystal structure of the electrolyte on electrical conductivity. ...

S. F. Palguev Z. S. Volchenkova

1968-01-01

357

Effect of the water-steam phase transition on electrical rock conductivity  

Microsoft Academic Search

The effect of the water-steam phase transition on electrical conductivity was experimentally investigated for four specimens of volcanic rocks from Icelandic geothermal reservoirs and one Fontainebleau sandstone sample. The measurements were performed at simulated in-situ conditions: The pore fluid chemistry was chosen to be similar in composition and electrical conductivity to the reservoir fluid; confining pressure, pore pressure, and temperature

H. Milsch; L. H. Kristinsdóttir; E. Spangenberg; D. Bruhn; O. G. Flóvenz

2009-01-01

358

Electrical Conductivity during XPS of Heated PMMA: Detection of Core Line and Valence Band Tacticity Effects.  

National Technical Information Service (NTIS)

Electrical conductivity during the XPS of approximately 100 nm thick films of PMMA on silicon was induced by heating to above 100 degrees C. Rapid x-ray induced depolymerization set in at about the same temperature. The electrical conductivity allowed acq...

G. Beamson D. T. Clark D. S. L. Law

1998-01-01

359

Electrical conduction mechanism in conjugated polymers studied using Flicker noise spectroscopy  

Microsoft Academic Search

We have performed detailed analysis of the fluctuations of the electrical current in electrochemically deposited conductive polymers (CP) using as example polyaniline and poly(3-methylthiophene). These heterogeneous and disordered materials cannot be analyzed in terms of classical conduction mechanisms (like Schottky or Poole–Frenkel emission). Instead, the electrical transport in CPs is to be considered as a stochastic process with large component

Vitali Parkhutik; Rahul Patil; Yutaka Harima; Eugenia Matveyeva

2006-01-01

360

Fracturing in saturated rocks undergoing triaxial deformation using complex electrical conductivity measurements: experimental study  

Microsoft Academic Search

Frequency dependent complex electrical conductivity measurements have been made on sandstones saturated with distilled water during triaxial deformation in both drained and undrained regimes. The resulting electrical and mechanical data show how the rock undergoes compaction, followed by dilatancy due to new crack formation, crack growth, interlinkage and failure as axial strain is increased. Electrical data are particularly good at

Paul W. J. Glover; Javier B. Gómez; P. G. Meredith

2000-01-01

361

Sea salt dependent electrical conduction in polar ice  

SciTech Connect

A 45 m length of ice core from Dolleman Island, Antarctic Peninsula has been dielectrically analyzed at 5 cm resolution using the dielectric profiling (DEP) technique. The core has also been chemically analyzed for major ionic impurities. A statistical analysis of the measurements shows that the LF (low frequency) conductivity is determined both by neutral salt and acid concentrations. The statistical relationships have been compared with results from laboratory experiments on ice doped with HF (hydrogen fluoride). Salts (probably dispersed throughout the ice fabric) determine the dielectric conductivity. The salt conduction mechanism is probably due to Bjerrum L defects alone, created by the incorporation of chloride ions in the lattice. Samples of ice from beneath the Filchner-Ronne Ice Shelf were also measured and display a similar conduction mechanism below a solubility limit of about 400 [mu]M of chloride. The temperature dependence of the neutral salt, acid and pure ice contributions to the LF conductivity of natural ice between [approximately] 70[degrees]C and 0[degrees]C is discussed. These results allow a comprehensive comparison of dielectric and chemical data from natural ice.

Moore, J.; Paren, J. (Natural Environment Research Council, Cambridge (United Kingdom)); Oerter, H. (Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany))

1992-12-10

362

Evaluation of electrical conductivity and equations of state of non-ideal plasma through microsecond timescale underwater electrical wire explosion  

SciTech Connect

Experimental and simulation results of underwater electrical Cu, Al, and W wire explosions in the microsecond timescale are presented. It was shown that the electrical conductivity results for Cu and Al agree well with modified Lee-More and quantum molecular dynamic models for temperatures above 10 kK. The equation of state (EOS) values based on SESAME tables for Cu and Al were slightly modified for intermediate temperatures in order to obtain fitting between experimental and simulated exploding wire radial expansion. Also, it was shown that the electrical conductivity results and the EOS evaluation differ significantly from the results obtained in nanosecond timescale experiments. Finally, it was found that underwater electrical W wire explosion is characterized by the appearance of non-uniformities along the z-axis of the wire. This phenomena adds uncertainty to the possibility of applying this type of experiments for evaluation of the electrical conductivity and EOS of W.

Sheftman, D.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

2011-09-15

363

Role of black carbon electrical conductivity in mediating hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) transformation on carbon surfaces by sulfides.  

PubMed

Recent research has demonstrated that black carbons catalyze the transformation of a range of nitrated explosives sorbed to the carbon surfaces in the presence of sulfides. Although surface oxygenated functional groups, particularly quinones, and electrical conductivity have both been hypothesized to promote these reactions, the importance of these properties has not been tested. In this work, the importance of electrical conductivity was addressed by producing chars of increasing electrical conductivity via pyrolysis of wood shavings at increasing temperature. The reactivity of chars with respect to transformation of the explosive RDX in the presence of sulfides correlated with electrical conductivity. Oxygenated functional groups were apparently not involved, as demonstrated by the elimination of reactivity of an activated carbon after ozone treatment or sorption of model quinones to the activated carbon surface. Although RDX transformation correlated with char electrical conductivity, no RDX transformation was observed when RDX was physically separated from sulfides but electrically connected through an electrochemical cell. RDX transformation occurred in the presence of a surface-associated sulfur species. The correlation with char electrical conductivity suggests that sulfides are oxidized on carbon surfaces to products that serve as potent nucleophiles promoting RDX transformation. PMID:23725551

Xu, Wenqing; Pignatello, Joseph J; Mitch, William A

2013-06-14

364

Local electrical conduction in polycrystalline La-doped BiFeO3 thin films  

NASA Astrophysics Data System (ADS)

Local electrical conduction behaviors of polycrystalline La-doped BiFeO3 thin films have been investigated by combining conductive atomic force microscopy and piezoelectric force microscopy. Nanoscale current measurements were performed as a function of bias voltage for different crystal grains. Completely distinct conducting processes and resistive switching effects were observed in the grain boundary and grain interior. We have revealed that local electric conduction in a grain is dominated by both the grain boundary and ferroelectric domain, and is closely related to the applied electric field and the as-grown state of the grain. At lower voltages the electrical conduction is dominated by the grain boundary and is associated with the redistribution of oxygen vacancies in the grain boundary under external electric fields. At higher voltages both the grain boundary and ferroelectric domain are responsible for the electrical conduction of grains, and the electrical conduction gradually extends from the grain boundary into the grain interior due to the extension of the ferroelectric domain towards the grain interior. We have also demonstrated that the conduction dominated by the grain boundary exhibits a much small switching voltage, while the conduction of the ferroelectric domain causes a much high switching voltage in the grain interior.

Zhou, Ming-Xiu; Chen, Bo; Sun, Hai-Bin; Wan, Jian-Guo; Li, Zi-Wei; Liu, Jun-Ming; Song, Feng-Qi; Wang, Guang-Hou

2013-06-01

365

Local electrical conduction in polycrystalline La-doped BiFeO? thin films.  

PubMed

Local electrical conduction behaviors of polycrystalline La-doped BiFeO3 thin films have been investigated by combining conductive atomic force microscopy and piezoelectric force microscopy. Nanoscale current measurements were performed as a function of bias voltage for different crystal grains. Completely distinct conducting processes and resistive switching effects were observed in the grain boundary and grain interior. We have revealed that local electric conduction in a grain is dominated by both the grain boundary and ferroelectric domain, and is closely related to the applied electric field and the as-grown state of the grain. At lower voltages the electrical conduction is dominated by the grain boundary and is associated with the redistribution of oxygen vacancies in the grain boundary under external electric fields. At higher voltages both the grain boundary and ferroelectric domain are responsible for the electrical conduction of grains, and the electrical conduction gradually extends from the grain boundary into the grain interior due to the extension of the ferroelectric domain towards the grain interior. We have also demonstrated that the conduction dominated by the grain boundary exhibits a much small switching voltage, while the conduction of the ferroelectric domain causes a much high switching voltage in the grain interior. PMID:23637078

Zhou, Ming-Xiu; Chen, Bo; Sun, Hai-Bin; Wan, Jian-Guo; Li, Zi-Wei; Liu, Jun-Ming; Song, Feng-Qi; Wang, Guang-Hou

2013-05-01

366

Morphological control of the electrochemical polymerization of electrically conducting polymers  

SciTech Connect

Unique morphologies have been found when pyrrole and 3-methylthiophene were electrochemically polymerized on two porous substrates, [open quotes]Nuclepore[close quotes] and stainless steel mesh. Polypyrrole formed highly oriented tubular fibrils on Nuclepore with striations along the direction of growth having conductivities between 2000 and 3000 S cm[sup [minus]1], higher than those observed in typical preparations of polypyrrole films. On the other hand, poly(3-methylthiophene) formed braided and spiralled fibrils. With the electrodes arranged horizontally, spiralled poly(3-methylthiophene) possessed temperatures independent conductivities.

Cahalane, W.F. Jr.

1993-01-01

367

Reversible temperature regulation of electrical and thermal conductivity using liquid-solid phase transitions  

PubMed Central

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions.

Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

2011-01-01

368

Electrical conductivity and discharge in spacecraft thermal control dielectrics  

Microsoft Academic Search

Engineering data on the radiation-induced and delayed conductivity in several common spacecraft dielectrics under conditions that approximate space exposure is presented. Direct measurements of discharge propagation velocity on Kapton, Teflon and Mylar is reported. Glass, and occasionally Mylar, exhibited discharges which propagated faster than 2 x 10⁸ cm\\/s, but persist at approx. =10⁻⁷ s.

B. C. Passenheim; R. Kitterer; J. D. Riddell; V. A. J. Van Lint

1982-01-01

369

Detecting Water Stress in Trees Using Stem Electrical Conductivity Measurements  

Microsoft Academic Search

Using time domain refl ectometry (TDR), we studied stem water content (?stem), stem elec- trical conductivity (?stem), and their ratio for 220 d in stressed, installation-cured, living trees of four species. Lysimeter-grown mango (Mangifera indica L.), banana (Musa acuminata Colla), date (Phoenix dactylifera L.), and olive (Olea europaea L.) were subjected to several types of mild (intensity and duration) water

Arie Nadler; Eran Raveh; Uri Yermiyahu; Marcos Lado; Ahmed Nasser; Mordechai Barak; Steve Green

2008-01-01

370

Temperature Dependence of Electrical Conductivity in Granular Metals.  

National Technical Information Service (NTIS)

A calculation is done to determine the range of temperature for hopping conduction (with a Log sigma equivalent Tsup(-1/2) law) and the average metallic grain size in granular metals. It is shown that the correlation between the separation of nearest neig...

G. Olivier M. Mostefa

1983-01-01

371

Correlation of mechanical and electrical relaxation phenomena in superionic conducting glasses  

SciTech Connect

The phenomenon of mechanical and electrical relaxation due to fast diffusing ions in glasses is placed in the context of relaxing dipolar and ionic liquids, and observation made at constant temperature are compared with those made at constant frequency. With this background several questions provoked by the apparent relations between mechanical and electrical responses are posed and answered within the limitations of currently available experimental data. Comparisons of average relaxation times, and of widths and shapes of relaxation spectra, are made. Finally, the authors present unifying plots which relate relaxational to vibrational responses for both electrical and mechanical stresses, the latter, they believe, for the first time.

Angell, C.A. (Purdue Univ., West Lafayette, IN (United States))

1989-01-01

372

Photoinduced extrinsic electrical conduction of nematic liquid crystal  

NASA Astrophysics Data System (ADS)

During recent years the interest in media with strong nonlinear response is growing. These media allow the user to observe different nonlinear optic effects using small intensities of light. It is well known that liquid crystals are rather promising media for this research. This paper is devoted to the experimental research of the photoinduced conduction of a mixture of a nematic liquid crystal and a dye. Dependence of the conduction on the intensity of light was studied for different concentrations of a dye added to the nematic crystal. Also the problem of the optimum type of a dye for observing the photorefractive nonlinearity using Ar+- ion laser was considered. We made the experiments using the following available laser dyes: rhodamine '6G,' rhodamine 'G,' rhodamine 'C' and two ocsasine-type dyes also. The mixture of the nematic crystal 5CB and a dye was placed in a cell of 100 micrometer width, with the plates filmed with the transparent electrodes of SnO2. The dc voltage on the order of magnitude 1 V was applied to decrease the influence of the cell capacity on the conduction measurements of the samples. We used the light of two wavelengths: lambda1 equals 488 nm, lambda2 equals 514.5 nm. The best dyes for these wavelengths were the rhodamine- type dyes. Taking the other two dyes we observed much smaller effect of influence of the laser radiation on conduction of the samples. Maybe the reason was that the pump wavelength of ocsasine dyes is too far way from the wavelength of the radiation used. So the optimum dye must have the wavelength of the pump near to the wavelength used. Using rhodamine 'C' we obtained the dependencies of the induced conduction on laser light intensity for three different concentrations of the dye.

Dedov, O. V.; Krivoschekov, V. A.

1996-05-01

373

Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2  

NASA Astrophysics Data System (ADS)

High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN2). Electrical conductivity of PPLP in LN2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

2013-11-01

374

Electrical conductivity and TSDC study of the thermal aging in conductive polypyrrole\\/polyaniline blends  

Microsoft Academic Search

The thermal aging of conducting polypyrrole\\/polyaniline (PPy\\/PA) blends heated at 70°C for up to about 600 hours was studied by d.c. conductivity measurements and by thermally stimulated depolarization current (TSDC) spectroscopy in the temperature range from 80 to 300 K. The composition of the samples varied from pure polypyrrole to pure polyaniline with the PA content increasing in steps of

S. Sakkopoulos; E. Vitoratos; J. Grammatikakis; A. N. Papathanassiou; E. Dalas

2002-01-01

375

Ceramic probe for measuring the thermal conductivity of an electrically conductive liquid by the transient hot wire method  

NASA Astrophysics Data System (ADS)

A new ceramic probe has been developed for measuring the thermal conductivity of an electrically conductive liquid by using the transient hot wire method. A wire was fabricated on a 10-mm-thick alumina substrate using a cofiring technique. To avoid leakage of the current to the liquid, the metallized wire was insulated with a 60-micron-thick alumina layer. Also developed for this probe is a method of compensating for the measurement error caused by increases in the resistance of metallized electrodes. The thermal conductivity of mercury was measured with this probe at temperatures of 300-382 K.

Nakamura, Shin; Hibiya, Taketoshi; Yamamoto, Fumio

1988-12-01

376

Electrical-Impedance Tomography for Opaque Multiphase Flows in Metallic (Electrically-Conducting) Vessels  

SciTech Connect

A novel electrical-impedance tomography (EIT) diagnostic system, including hardware and software, has been developed and used to quantitatively measure material distributions in multiphase flows within electrically-conducting (i.e., industrially relevant or metal) vessels. The EIT system consists of energizing and measuring electronics and seven ring electrodes, which are equally spaced on a thin nonconducting rod that is inserted into the vessel. The vessel wall is grounded and serves as the ground electrode. Voltage-distribution measurements are used to numerically reconstruct the time-averaged impedance distribution within the vessel, from which the material distributions are inferred. Initial proof-of-concept and calibration was completed using a stationary solid-liquid mixture in a steel bench-top standpipe. The EIT system was then deployed in Sandia's pilot-scale slurry bubble-column reactor (SBCR) to measure material distributions of gas-liquid two-phase flows over a range of column pressures and superficial gas flow rates. These two-phase quantitative measurements were validated against an established gamma-densitometry tomography (GDT) diagnostic system, demonstrating agreement to within 0.05 volume fraction for most cases, with a maximum difference of 0.15 volume fraction. Next, the EIT system was combined with the GDT system to measure material distributions of gas-liquid-solid three-phase flows in Sandia's SBCR for two different solids loadings. Accuracy for the three-phase flow measurements is estimated to be within 0.15 volume fraction. The stability of the energizing electronics, the effect of the rod on the surrounding flow field, and the unsteadiness of the liquid temperature all degrade measurement accuracy and need to be explored further. This work demonstrates that EIT may be used to perform quantitative measurements of material distributions in multiphase flows in metal vessels.

LITER, SCOTT G.; TORCZYNSKI, JOHN R.; SHOLLENBERGER, KIM A.; CECCIO, STEVEN L.

2002-10-01

377

Electrical and surface properties of clay-conducting polymer composites  

NASA Astrophysics Data System (ADS)

Organic guests such as aniline, pyrrole and thiophene polymerize on the surface and in the intergallery regions of smectite clays which contain exchangeable transition metal cations such as Cu2+ and Fe3+. We monitor these reactions in thin films of smectite clays using electron spin resonance (ESR) and impedance spectroscopies. Polymers that form on the surface and in the interlayer region are studied by scanning force microscopy (SFM). ESR studies have shown that the transition metal ions are reduced during the polymerization process. Impedance measurements indicate that the formation of conducting polymer in the interlayer region of dry, Cu2+ exchanged hectorite thin films results in a dramatic reduction in observed impedance. SFM scans indicate that the conducting polymers can adopt a variety of morphologies on the surfaces of the films and within the intergalleries of the host framework. These studies have applications in the development of advanced materials including microsensors and novel nanocomposites.

Eastman, M. P.; Hagerman, M. E.; Porter, T. L.; Parnell, R. A.; Attuso, J. L.; Bradley, M.; Thompson, D.

1997-08-01

378

Intermolecular electrical conductance in self-assembled monolayers  

NASA Astrophysics Data System (ADS)

Intermolecular interaction was investigated by measuring the properties of self-assembled monolayers (SAMs) in the lateral direction. We formed SAMs of octadecyltrichlorosilane (OTS) and phenethyltrichlorosilane with Ag- or Au-patterned electrodes on mica surfaces and measured the conductance under various bias voltages. Using an atomic force microscope with a conductive cantilever, we could not detect current through the SAMs in the vicinity of the electrodes about 85 nm from the edge. The resistivity of the OTS film measured using the substrates with interdigitated (comb) electrodes was strongly dependent on the humidity. From the result in a dry N2 atmosphere, the resistivity of a SAM of OTS in a lateral direction was estimated to be 9×1010 ?cm.

Inoue, A.; Mizutani, W.; Ishida, T.; Tokumoto, H.

379

Electrical conductivity of cationized ferritin decorated gold nanoshells  

NASA Astrophysics Data System (ADS)

We report on a novel method of controlling the resistance of nanodimensional, gold-coated SiO2 nanoparticles by utilizing biomolecules chemisorbed to the nanoshell surface. Local electronic transport properties of gold-coated nanoshells were measured using scanning conductance microscopy. These results were compared to transport properties of identical gold nanoshells biofunctionalized with cationized ferritin protein both with and without an iron oxide core (apoferritin). Measured resistances were on the order of mega-ohms. White light irradiation effects on transport properties were also explored. The results suggest that the light energy influences the nanoshells' conductivity. A mechanism for assembly of gold nanoshells with cationized ferritin or cationized apoferritin is proposed to explain the resistivity dependence on irradiation.

Cortez, Rebecca; Slocik, Joseph M.; Van Nostrand, Joseph E.; Halas, Naomi J.; Naik, Rajesh R.

2012-06-01

380

The electrical conductivity of fluidized bed electrodes—its significance and some experimental measurements  

Microsoft Academic Search

By applying a mathematical model (developed by Newman and Tobias for porous electrodes) to a fluidized bed electrode it can\\u000a be concluded that the effective electrical conductivity of the bed is a key parameter affecting bed performance. Poor current\\u000a and power efficiencies and operational difficulties are predicted for beds with low electrical conductivities and it is suggested\\u000a that high conductivities

B. J. Sabacky; J. W. Evans

1977-01-01

381

Electronic Processes in Solutions of Alkali Metals in Liquid Ammonia. II. Electrical Conductivity  

Microsoft Academic Search

An attempt has been made to account for the electrical conductivity in sodium\\/liquid-ammonia solutions throughout the entire range of concentrations. The conductivity in dilute solutions is calculated from the Onsager—Kim theory, adjusted for the effective concentrations of conducting species. In the intermediate concentration range a conduction mechanism is proposed, according to which the conduction proceeds by the jumping of electrons

Emil Arnold; Andrew Patterson Jr.

1964-01-01

382

Simple Method for Estimating the Electrical Conductivity of Oxide Melts with Optical Basicity  

NASA Astrophysics Data System (ADS)

The electrical conductivity of oxide melts is an important physicochemical property for designing the electric smelting furnaces. Although the data of many slag systems have been measured, the quantitative relationships of electrical conductivity to slag composition and temperature are still limited. In this article, a model is proposed based on the optical basicity corrected for the cations required for the charge balance of {{AlO}}_{ 4}^{ 5- } , in which Arrhenius Law is used to describe the relationship between electrical conductivity and temperature. In this model, the activation energy is expressed as a linear function of the corrected optical basicity. Successful applications to CaO-MgO-Al2O3-SiO2 and CaO-Al2O3-SiO2 systems indicate that this model can work well in the electrical conductivity estimation.

Zhang, Guo-Hua; Chou, Kuo-Chih

2010-02-01

383

Silver-polyaniline-epoxy electrical conductive adhesives - a percolation threshold analysis  

Microsoft Academic Search

Electrical conductive adhesives (ECA) find extensive applications in electronic manufacturing and packaging industries. Compared to the soldering technology, adhesives joining offer numerous advantages including mild processing conditions, fewer processing steps (reducing process cost), and especially, the fine pitch capability due to the availability of small size conductive fillers. ECAs function based on the conductive fillers, typically 1–10µm in size, supported

Sarang P. Gumfekar; Alex Chen; Boxin Zhao

2011-01-01

384

In situ electrical conductivity measurement of select liquid foods under hydrostatic pressure to 800 MPa  

Microsoft Academic Search

Electrical conductivity of select liquid foods and salt solutions was measured in situ during high pressure processing using a specially designed parallel electrode conductivity cell. Cell constants at atmospheric pressure were determined with KCl standards and calculated against standard data, while cell constants under pressure were estimated assuming isotropic compression. Measured conductivities of NaCl solutions under pressure were within 5.7%

Stephen Min; S. K. Sastry; V. M. Balasubramaniam

2007-01-01

385

High frequency electrical conduction block of the pudendal nerve  

NASA Astrophysics Data System (ADS)

A reversible electrical block of the pudendal nerves may provide a valuable method for restoration of urinary voiding in individuals with bladder-sphincter dyssynergia. This study quantified the stimulus parameters and effectiveness of high frequency (HFAC) sinusoidal waveforms on the pudendal nerves to produce block of the external urethral sphincter (EUS). A proximal electrode on the pudendal nerve after its exit from the sciatic notch was used to apply low frequency stimuli to evoke EUS contractions. HFAC at frequencies from 1 to 30 kHz with amplitudes from 1 to 10 V were applied through a conforming tripolar nerve cuff electrode implanted distally. Sphincter responses were recorded with a catheter mounted micro-transducer. A fast onset and reversible motor block was obtained over this range of frequencies. The HFAC block showed three phases: a high onset response, often a period of repetitive firing and usually a steady state of complete or partial block. A complete EUS block was obtained in all animals. The block thresholds showed a linear relationship with frequency. HFAC pudendal nerve stimulation effectively produced a quickly reversible block of evoked urethral sphincter contractions. The HFAC pudendal block could be a valuable tool in the rehabilitation of bladder-sphincter dyssynergia.

Bhadra, Narendra; Bhadra, Niloy; Kilgore, Kevin; Gustafson, Kenneth J.

2006-06-01

386

Latent synthesis of electrically conductive surface-silvered polyimide films.  

PubMed

A facile ambient temperature route to the fabrication of surface silver-metallized polyimide films is described. Silver(I) trifluoromethanesulfonate or silver(I) nitrate and a polyimide, derived from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and an equimolar amount of 4,4'-oxydianiline and 3,5-diaminobenzoic acid, were dissolved together in dimethylacetamide. Silver(I)-doped films were prepared at thicknesses of 25-40 microm and depleted of solvent by evaporation at ambient temperature and low humidity. The silver(I)-ion-containing films were then treated with aqueous solutions of the reducing agents hydrazine hydrate and hydroxylamine, which brought forth surface-silvered films exhibiting conductivity on the order of bulk polycrystalline silver accompanied by modest-to-high specular reflectivity. PMID:20355773

Davis, Luke M; Abelt, Christopher J; Scott, Joseph L; Orlova, Evguenia; Thompson, David W

2009-01-01

387

Electrical conductivity of hydrous basaltic melts: implications for partial melting in the upper mantle  

Microsoft Academic Search

The Earth’s uppermost asthenosphere is generally associated with low seismic wave velocity and high electrical conductivity.\\u000a The electrical conductivity anomalies observed from magnetotelluric studies have been attributed to the hydration of mantle\\u000a minerals, traces of carbonatite melt, or silicate melts. We report the electrical conductivity of both H2O-bearing (0–6 wt% H2O) and CO2-bearing (0.5 wt% CO2) basaltic melts at 2 GPa and 1,473–1,923 K

Huaiwei Ni; Hans Keppler; Harald Behrens

2011-01-01

388

Simultaneous measurements of thermal conductivity and electrical conductivity of micro-machined Silicon films  

Microsoft Academic Search

The in-plane effective thermal conductivity of free-standing Si thin films with periodic micropores was measured at -100 to 0 °C. The Si thin films with micropores were prepared from silicon-on-insulator (SOI) wafers by standard microfabrication processes. The dimensions of the free-standing Si thin films were 200?m×150?m×2 ?m, with staggered 4 ?m pores having an average pitch of 4 mm. The

H Hagino; Y Kawahara; A Goto; K Miyazaki

2012-01-01

389

Electrical conductivity of talc aggregates at 0.5 GPa: influence of dehydration  

NASA Astrophysics Data System (ADS)

Electrical conductivity of talc was measured at 0.5 GPa and ~473 to ~1,300 K by using impedance spectroscopy both before and after dehydration. Before dehydration, the electrical conductivity of talc increased with temperature and is ~10-4 S/m at 1,078 K. After dehydration, most of the talc changed to a mixture of enstatite and quartz and the total water content is reduced by a factor 6 or more. Despite this large reduction in the total water content, the electrical conductivity increased. The activation enthalpy of electrical conductivity (~125 kJ/mol) is too large for the conduction by free water but is consistent with conduction by small polaron. Our results show that a majority of hydrogen atoms in talc do not enhance electrical conductivity, implying the low mobility of the hydrogen atoms in talc. The observed small increase in conductivity after dehydration may be attributed to the increase in oxygen fugacity that enhances conductivity due to small polaron.

Wang, Duojun; Karato, Shun-ichrio

2013-01-01

390

Effects of electrical conductivity of irrigation water on the growth and production of Solanum lycopersicum L. var. cerasiforme grown in greenhouse  

Microsoft Academic Search

Tomato (Solanum lycopersicum L.) is commonly considered moderately tolerant to salinity and its tolerance varies in relation to genotype and the plant's organ. With regard to the latter aspect, it was found that the negative effects of salinity become apparent with electrical conductivity values of the circulating solution starting from 2.5 - 3.0 dS m-1 for the fruits, from 4.5

M. Marchese; R. Tuttobene; A. Restuccia; A. M. G. Longo; G. Mauromicale; G. Restuccia

391

Iodine doped carbon nanotube cables exceeding specific electrical conductivity of metals  

PubMed Central

Creating highly electrically conducting cables from macroscopic aggregates of carbon nanotubes, to replace metallic wires, is still a dream. Here we report the fabrication of iodine-doped, double-walled nanotube cables having electrical resistivity reaching ?10?7??.m. Due to the low density, their specific conductivity (conductivity/weight) is higher than copper and aluminum and is only just below that of the highest specific conductivity metal, sodium. The cables exhibit high current-carrying capacity of 104?105?A/cm2 and can be joined together into arbitrary length and diameter, without degradation of their electrical properties. The application of such nanotube cables is demonstrated by partly replacing metal wires in a household light bulb circuit. The conductivity variation as a function of temperature for the cables is five times smaller than that for copper. The high conductivity nanotube cables could find a range of applications, from low dimensional interconnects to transmission lines.

Zhao, Yao; Wei, Jinquan; Vajtai, Robert; Ajayan, Pulickel M.; Barrera, Enrique V.

2011-01-01

392

Iodine doped carbon nanotube cables exceeding specific electrical conductivity of metals  

NASA Astrophysics Data System (ADS)

Creating highly electrically conducting cables from macroscopic aggregates of carbon nanotubes, to replace metallic wires, is still a dream. Here we report the fabrication of iodine-doped, double-walled nanotube cables having electrical resistivity reaching ~10-7 ?.m. Due to the low density, their specific conductivity (conductivity/weight) is higher than copper and aluminum and is only just below that of the highest specific conductivity metal, sodium. The cables exhibit high current-carrying capacity of 104~105 A/cm2 and can be joined together into arbitrary length and diameter, without degradation of their electrical properties. The application of such nanotube cables is demonstrated by partly replacing metal wires in a household light bulb circuit. The conductivity variation as a function of temperature for the cables is five times smaller than that for copper. The high conductivity nanotube cables could find a range of applications, from low dimensional interconnects to transmission lines.

Zhao, Yao; Wei, Jinquan; Vajtai, Robert; Ajayan, Pulickel M.; Barrera, Enrique V.

2011-09-01

393

Improvement of Electrical Contact Reliability by Conductive Polymer Coated Elastomer Structure in Woven Electronic Textiles  

NASA Astrophysics Data System (ADS)

This article presents an improvement in the stability and durability of the electrical contacts employed in flexible devices. A coating of poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) in form of a solid conductive layer on a silicone elastomer structure is employed in creating an electrical circuit embedded into the fabric of a woven electronic textile, where the coating serves as an electrical contact between weft and warp ribbons. When the contact load increases to 1 mN, then, due to the flexibility of the structure, an electric current begins to flow through the circuit. The structure can sextuplicate the life of the electrical contact.

Yamashita, Takahiro; Takamatsu, Seiichi; Miyake, Koji; Itoh, Toshihiro

2012-12-01

394

Synthesis and electric conductivity of a NASICON-type electrolyte  

SciTech Connect

The purpose of this work was to study the sequence of solid-phase reactions in the synthesis of the solid electrolyte, corresponding to the stoichiometric composition Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/. The solid-phase reaction of the mixture ZrO(NO/sub 3/)/sub 2/ x 2H/sub 2/O, Na/sub 2/CO/sub 3/, NH/sub 4/H/sub 2/PO/sub 4/ and amorphous SiO/sub 2/ proceeds through the stage of dehydration of zirconium oxide-nitrate, decomposition of ammonium dihydrophosphate, and formation and decomposition of ammonium and sodium nitrates. The intermediate products of the reaction are sodium and zirconium phosphates, and part of the ZrO/sub 2/ participates in the reaction in the form of an amorphous or metastable tetragonal modification, while part transforms into a stable monoclinic modification. The formation of NASICON starts near 1000/sup 0/C, and in addition silicon dioxide, which can first transform from the amorphous state into the mixture of tridymite and ..cap alpha..-cristobalite, participates in the reaction only at this stage. After annealing at 1230/sup 0/C the single-phase solid electrolyte Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/, having a conductivity of 0.14 S/cm at 300/sup 0/C and 0.00028 S/cm at 25/sup 0/C, is obtained.

Bukun, N.G.; Domashnev, I.A.; Moskvina, E.I.; Ukshe, E.A.

1988-08-01

395

Origin of High Electrical Conductivity in the Lower Continental Crust: A Review  

NASA Astrophysics Data System (ADS)

Electromagnetic measurements have demonstrated that the lower continental crust has remarkable electrical anomalies of high conductivity and electrical anisotropy on a global scale (probably with some local exceptions), but their origin is a long-standing and controversial problem. Typical electrical properties of the lower continental crust include: (1) the electrical conductivity is usually 10-4 to 10-1 S/m; (2) the overlying shallow crust and underlying upper mantle are in most cases less conductive; (3) the electrical conductivity is statistically much higher in Phanerozoic than in Precambrian areas; (4) horizontal anisotropy has been resolved in many areas; and (5) in some regions there appear to be correlations between high electrical conductivity and other physical properties such as seismic reflections. The explanation based on conduction by interconnected, highly conductive phases such as fluids, melts, or graphite films in grain boundary zones has various problems in accounting for geophysically resolved electrical conductivity and other chemical and physical properties of the lower crust. The lower continental crust is dominated by mafic granulites (in particular beneath stable regions), with nominally anhydrous clinopyroxene, orthopyroxene, and plagioclase as the main assemblages, and the prevailing temperatures are mostly 700-1,000°C as estimated from xenolith data, surface heat flow, and seismic imaging. Pyroxenes have significantly higher Fe content in the lower crust than in the upper mantle (peridotites), and plagioclase has higher Na content in the lower crust than in the shallow crust (granites). Minerals in the lower continental crust generally contain trace amounts of water as H-related point defects, from less than 100 to more than 1,000 ppm H2O (by weight), with concentrations usually higher than those in the upper mantle. Observations of xenolith granulites captured by volcano-related eruptions indicate that the lower continental crust is characterized by alternating pyroxene-rich and plagioclase-rich layers. Experimental studies on typical lower crustal minerals have shown that their electrical conductivity can be significantly enhanced by the higher contents of Fe (for pyroxenes), Na (for plagioclase), and water (for all minerals) at thermodynamic conditions corresponding to the lower continental crust, e.g., to levels comparable to those measured by geophysical field surveys. Preferred orientation of hydrous plagioclase, e.g., due to ductile flow in the deep crust, and alternating mineral fabrics of pyroxene-rich and plagioclase-rich layers can lead to substantial anisotropy of electrical conductivity. Electrical conductivity properties in many regions of the lower continental crust, especially beneath stable areas, can mostly be accounted for by solid-state conduction due to the major constituents; other special, additional conduction mechanisms due to grain boundary phases are not strictly necessary.

Yang, Xiaozhi

2011-11-01

396

Ab initio determination of electrical and thermal conductivity of liquid aluminum  

NASA Astrophysics Data System (ADS)

We present here a technique to compute electronic thermal conductivity of fluids using quantum-molecular dynamics and the formulation of Chester-Tellung for the Kubo-Greenwood formula. In order to validate our implementation, the electrical and thermal conductivities of liquid aluminum were determined from 70K above the melting point up to 10000K . Results agree well with experimental data for Al at 1000K . The Lorentz number, defined as K/?T , where K is the thermal conductivity, ? is the electrical conductivity, and T is the temperature, is close to the ideal value of 2.44×10-8 for metals, and the Wiedemann-Franz law is verified.

Recoules, Vanina; Crocombette, Jean-Paul

2005-09-01

397

Update of Thermal Conductivity and Electrical Resistivity of Electrolytic Iron, Tungsten, and Stainless Steel.  

National Technical Information Service (NTIS)

An update is given of the thermal conductivity and electrical resistivity of the metals: electrolytic iron, tungsten, and stainless steel. This document describes the measurement effort that has occurred since the establishment of these SRM's. New data ar...

J. G. Hust A. B. Lankford

1984-01-01

398

Temperature and Electrical Conductivity of the Lunar Interior from Magnetic Transient Measurements in the Geomagnetic Tail.  

National Technical Information Service (NTIS)

Magnetometers have been deployed at four Apollo sites on the moon to measure remanent and induced lunar magnetic fields. Measurements from this network of instruments have been used to calculate the electrical conductivity, temperature, magnetic permeabil...

P. Dyal C. W. Parkin W. D. Daily

1973-01-01

399

Temperature and Electrical Conductivity of the Lunar Interior from Magnetic Transient Measurements in the Geomagnetic Tail.  

National Technical Information Service (NTIS)

Magnetometers were deployed at four Apollo sites on the moon to measure remanent and induced lunar magnetic fields. Measurements from this network of instruments were used to calculate the electrical conductivity, temperature, magnetic permeability, and i...

P. Dyal C. W. Parkin W. D. Daily

1974-01-01

400

Electrical conductivity and viscosity of melts of products of the reaction of zirconium with potassium halides  

SciTech Connect

The authors report results of a study of the electrical conductivity and viscosity of melts of products of the reaction of zirconium with potassium chloride and fluoride in binary and ternary mixtures composed of these substances.

Trifonov, K.I.; Zagidulin, S.M.; Katyshev, S.F.; Desyatnik, V.N.

1986-12-20

401

Electrical and heat conduction mechanisms of GeTe alloy for phase change memory application  

NASA Astrophysics Data System (ADS)

GeTe alloy has drawn much attention as one of the promising candidates for phase change memory application. In this work, the electrical resistivities and thermal conductivities of GeTe alloy have been determined as functions of temperature by the four-terminal method and hot strip method, respectively. The electrical resistivity increases and the thermal conductivity decreases monotonically with increasing temperature, and thus it is likely that free electron dominates the thermal conduction. The electrical resistivity increases slowly with time during holding at 773 K, and the thermal conductivity decreases corresponding to the change of the electrical resistivity, which suggests that small amount of high temperature phase might exist in the samples.

Lan, Rui; Endo, Rie; Kuwahara, Masashi; Kobayashi, Yoshinao; Susa, Masahiro

2012-09-01

402

USSR Certificate of Authorship No. 755,772. A Method of Preparing an Electrically Conductive Composition.  

National Technical Information Service (NTIS)

A method is described for preparing an electrically conducting composition for the purpose of metallizing unfired piezoceramic material, including the preparation of a paste based on silver, characterized by the fact that in order to prevent the burning-o...

V. D. Rogozin A. F. Trudov V. V. Lebedev A. V. Popov

1981-01-01

403

The Effect of Electrical Conductivity Variations on the Characteristics of Arc Discharges.  

National Technical Information Service (NTIS)

Algebraically calculated current-voltage characteristics of arc discharges are obtained with a canal model for planar and cylindrical arcs and electrical conductivity given as a power of the heat flux potential. For slower than linear variation, the curre...

A. M. Whitman I. M. Cohen

1973-01-01

404

Magnetic Flowmeter for Electrically Conductive Fluids: Improved accuracy is provided with minimum recalibration requirements.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. Fluid velocity of electrically conductive liquids, such as liquid metals, is measured more accurately and efficiently with a calibrated magnetic flowmeter that opera...

1984-01-01

405

Electrical Conductivity in Polymer Composites Containing Metal Nanowires: Simulation and Experiment  

NASA Astrophysics Data System (ADS)

The study of rod percolation behavior has resurfaced in recent years, because it explains electrical conductivity in polymer nanocomposites containing carbon nanotubes and metal nanowires. Common processing techniques result in fillers with L/D < 50, so traditional models, which are only strictly correct in the limit of L/D ˜?, are ineffective at predicting percolation in these systems. We present a simulation that constructs percolated networks of finite-aspect ratio rods and calculates their electrical conductivity. We will compare our simulation results with polymer composites containing silver nanowires with aspect ratios of ˜10 and ˜30. Finally, we will present the temperature-dependent electrical conductivity of these composites and interpret the results using the thermal expansion coefficients of polystyrene and silver. These materials act as ``thermal switches,'' wherein electrical conductivity of certain composites can be manipulated by several orders of magnitude over the temperature range from 80K-425 K.

White, Sadie; Vemulkar, Tarun; Fischer, John; Winey, Karen

2009-03-01

406

Low temperature electrical conductivity of low-density polyethylene/carbon black composites  

NASA Astrophysics Data System (ADS)

The study deals with the electrical characteristics of carbon black/low-density polyethylene (CB/LDPE) composites of various CB filler concentrations (10, 15, and 20% wt.). DC-electrical conductivity was studied as a function of filler concentration in the low temperature range 25--285K. It was found that the composites exhibit a negative temperature coefficient of resistivity (TCR) at low temperatures and a high enhancement in electrical conductivity with both temperature and carbon black concentration. The observed increase of conductivity with the filler concentration was interpreted through percolation theory. The dependence of the electrical conductivity of the given composites on temperature (25--285 K) was analyzed in terms of a formula consistent with the Mott hopping mechanism.

Tawalbeh, Tarek; Saq'an, Subhi; Yasin, Shadi; Zihlif, Awwad; Ragosta, Giuseppe

2011-03-01

407

Electrical conduction of high-conductivity layers near the surfaces in hydrogenated homoepitaxial diamond films  

NASA Astrophysics Data System (ADS)

In order to clarify the origin of high-conductivity layers (HCL) near the surfaces of hydrogenated diamond films, we have studied the relationship between HCL and surface structure in B-doped homoepitaxial (001) diamond films. Samples annealed in nitrogen environment at various temperatures have been characterized by Hall-effect measurements and reflection high-energy electron diffraction. It was found that HCL disappeared in the films annealed at a temperature higher than 350°C, but the (001)-2×1 surface-structures observed in hydrogenated films remained at 350°C. This indicates that HCL is not related directly with the (001)-2×1 surface-structure. The origin of HCL will be discussed on the basis of the present results.

Yamanaka, S.; Takeuchi, D.; Watanabe, H.; Okushi, H.; Kajimura, K.

2000-06-01

408

Nerve Growth Factor-Immobilized Electrically Conducting Fibrous Scaffolds for Potential Use in Neural Engineering Applications  

Microsoft Academic Search

Engineered scaffolds simultaneously exhibiting multiple cues are highly desirable for neural tissue regeneration. To this end, we developed a neural tissue engineering scaffold that displays submicrometer-scale features, electrical conductivity, and neurotrophic activity. Specifically, electrospun poly(lactic acid-co-glycolic acid) (PLGA) nanofibers were layered with a nanometer thick coating of electrically conducting polypyrrole (PPy) presenting carboxylic groups. Then, nerve growth factor (NGF) was

Jae Y. Lee; Chris A. Bashur; Craig A. Milroy; Leandro Forciniti; Aaron S. Goldstein; Christine E. Schmidt

2012-01-01

409

Electrical conductivity and dielectric response of poly(vinylidene fluoride)–graphite nanoplatelet composites  

Microsoft Academic Search

Poly(vinylidene fluoride)\\/graphite nanoplatelets (PVDF\\/GNP) composites were fabricated using solution mixing followed by compression molding. The electric conducting and dielectric behavior of such nanocomposites were determined over a wide frequency range from 102 to 107. The results showed that the electrical behavior of PVDF\\/GNP nanocomposites can be well described by the percolation theory. Both conductivity and dielectric constant were found to

Y. C. Li; S. C. Tjong; R. K. Y. Li

2010-01-01

410

Electrical conductivity of ?-Al 2O 3 at atmospheric pressure under dehydrating\\/hydrating conditions  

Microsoft Academic Search

Changes of electrical conductance and capacity of ?-Al2O3 were studied in situ during dehydration\\/rehydration in gas flow. The measurements were performed at atmospheric pressure by following a standard protocol of experiments, and were coupled with simultaneous monitoring of the composition of the inlet\\/effluent gas.The electrical properties are dominated by the protonic conduction. It was shown that at low temperature this

M. Caldararu; G. Postole; C. Hornoiu; V. Bratan; M. Dragan; N. I. Ionescu

2001-01-01

411

Light transmissive electrically conductive oxide electrode formed in the presence of a stabilizing gas  

SciTech Connect

A light transmissive, electrically conductive oxide is doped with a stabilizing gas such as H[sub 2] and H[sub 2]O. The oxide is formed by sputtering a light transmissive, electrically conductive oxide precursor onto a substrate at a temperature from 20 C to 300 C. Sputtering occurs in a gaseous mixture including a sputtering gas and the stabilizing gas. 7 figs.

Tran, N.T.; Gilbert, J.R.

1992-08-04

412

Quasi-DC Terahertz Electrical Conductivity Measurements of Dense Aluminum Plasma  

Microsoft Academic Search

We report on our investigation of electrical transport in ultrashort laser-heated aluminum. By measuring the complex electrical conductivity at terahertz (THz = 10^12 Hz) frequencies, we explore the dependence of electrical transport across the material phase transition from the cold solid to the dense plasma state. Using optical-pump, terahertz-probe spectroscopy, we measure the phase shifts and absorption of terahertz probe

George Rodriguez; Balakishore Yellampalle; James Glownia; Antoinette Taylor; Ki-Yong Kim

2007-01-01

413

Near Surface Electrical Characterization of Hydraulic Conductivity: From Petrophysical Properties to Aquifer Geometries—A Review  

Microsoft Academic Search

This paper reviews the recent geophysical literature addressing the estimation of saturated hydraulic conductivity (K) from static low frequency electrical measurements (electrical resistivity, induced polarization (IP) and spectral induced\\u000a polarization (SIP)). In the first part of this paper, research describing how petrophysical relations between electrical properties\\u000a and effective (i.e. controlling fluid transport) properties of (a) the interconnected pore volumes and

Lee Slater

2007-01-01

414

Influence of Wetted-Phase Structure on the Electrical Conductivity-Moisture Content Relationship  

Microsoft Academic Search

Knowledge of the relationship between the soil bulk electrical conductivity (EC) and moisture content is required to quantify subsurface moisture variations using electrical resistance tomography (ERT). Repacked field samples are typically used to establish the EC-moisture content relationship, because of difficulty removing and analyzing intact samples. However internal sample structure can influence EC measurements, as complicated wetted-phase structures can evolve

R. M. Holt; E. D. Mattson

2002-01-01

415

Characteristics of convection of an electrically conducting liquid in an additional external force field  

SciTech Connect

The authors analyze, theoretically and experimentally, the combined effects of gravitational and electric fields along with inertial forces on convective heat and mass transfer in liquid metals undergoing vortex flow in the presence of constant magnetic fields. The experimental data are derived for a eutectic indium-gallium-tin alloy. The flow model incorporates electrical conductivity and Hartmann number as well as other properties.

Mikel'son, A.E.; Karklin, Ya.Kh.

1987-07-01

416

Quality factor of an electrically small antenna radiating close to a conducting plane  

Microsoft Academic Search

Expressions are derived for the smallest achievable radiation quality factor (Q) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. The contribution of non-propagating energy

J. C.-E. Sten; A. Hujanen; P. K. Koivisto

2001-01-01

417

Field and temperature dependence of the small polaron hopping electrical conductivity in 1D disordered systems  

Microsoft Academic Search

We investigate the effect of the electric field and the temperature on the electrical conductivity of one-dimensional disordered systems due to phonon assisted hopping of small polarons. The microscopic transport mechanism is treated within the framework of the generalized molecular crystal model and the Kubo formula, while percolation theoretical arguments lead to analytical expressions for the macroscopic behavior of the

G. P. Triberis; M. Dimakogianni

2009-01-01

418

Cardiovascular and Physiologic Effects of Conducted Electrical Weapon Discharge in Resting Adults  

Microsoft Academic Search

Objectives: The TASER is a conducted electrical weapon (CEW) that has been used on people in custody. Individuals occasionally die unexpectedly while in custody, proximal to the application of a CEW. In this study, the authors sought to examine the effects of CEW application in resting adult volunteers to deter- mine if there was evidence of induced electrical dysrhythmia or

Jeffrey D. Ho; James R. Miner; Dhanunjaya R. Lakireddy; Laura L. Bultman; William G. Heegaard

2006-01-01

419

Effects of surface-active demulsifiers on electrical conductivity of emulsions of water in crude oil  

Microsoft Academic Search

This article examines the effects of various emulsifiers on the electrical conductivity (EC) of emulsions of water in crude oil under conditions approaching the conditions prevailing in crude oil demulsification in electrocoalescing vessels. It is assumed that the EC of inverse hydrocarbon emulsions depends on the strength of the electric field. Beginning at a field strength of some hundreds of

A. A. Yunusov; G. M. Akhmadiev; G. A. Babalyan

1984-01-01

420

Influence of temperature on the electrical conductivity of leachate from municipal solid waste.  

PubMed

A bioreactor landfill is designed to manage municipal solid waste, through accelerated waste biodegradation, and stabilisation of the process by means of the controlled addition of liquid, i.e. leachate recirculation. The measurement of electrical resistivity by Electrical Resistivity Tomography (ERT) allows to monitor water content present in the bioreactors. Variations in electrical resistivity are linked to variations in moisture content and temperature. In order to overcome this ambiguity, two laboratory experiments were carried out to establish a relationship between temperature and electrical conductivity: the first set of measurements was made for leachate alone, whereas the second set was made with two different granular media saturated with leachate. Both experiments confirm a well known increase in conductivity of about 2% degrees C(-1). However, higher suspended matter concentrations lead to a lower dependence of electrical conductivity on temperature. Furthermore, for various porous media saturated with an identical leachate, the higher the specific surface of the granular matrix, the lower the effective bulk electrical conductivity. These observations show that a correct understanding of the electrical properties of liquids requires the nature and (in particular) the size of the electrical charge carriers to be taken into account. PMID:16600494

Grellier, Solenne; Robain, Henri; Bellier, Gérard; Skhiri, Nathalie

2006-04-05

421

Quantitative evaluation of the electrically conductive internal network in CFRP composites  

NASA Astrophysics Data System (ADS)

The electrical resistance change of CFRP composite under mechanical loading condition can be used as an effective parameter to evaluate the accumulated internal damage. The internal electrically conductive network, which is constructed by the contacts between conductive carbon fibers, is very important in correlating the resistance change to mechanical damage state. The electrical ineffective length (delta) ec, the mean distance between adjacent contact points, can be used as a useful parameter to evaluate the internal conductive network. In this study, a new methodology for the evaluation of the internal conducting network is proposed. For this purpose, the electrically anisotropic characteristics of the CFRP composite are measured using the DC 4 probe and the DC 6 probe methods and the values of (delta) ec are estimated using the mechanical tensile test for various fiber volume fractions. Based on the experimental results, the empirical relationship between the electrical anisotropy and (delta) ec is established. We also conduct the DC network circuit analysis using Kirchhoff's rule and the Monte Carlo simulation of the contact point distribution, and calculate the (delta) ec for various contact configurations. By comparing the analytical and experimental results, the distribution configuration and the number of contact points, which constitute the internal electrically conductive network of CFRP composites, can be evaluated quantitatively.

Park, Jae B.; Okabe, Tomonaga; Yoshimura, Akinori; Takeda, Nobuo; Curtin, William A.

2002-06-01

422

Electrical Conductivity Response toward Ketone Vapors of Poly(Para-Phenylene Vinylene)/Zeolite Y Composites  

NASA Astrophysics Data System (ADS)

Investigation of the effect of 3 different types of cation types in Zeolite Y; Zeolite Y(Si/Al=5.1, Na+), Zeolite Y(Si/Al=5.1, NH3+), Zeolite Y(Si/Al=5.1, H+) on the electrical conductivity sensitivity when exposed to the 3 different types of ketone vapors (Acetone, Methyl Ethyl Ketone(MEK) and Methyl Iso Buthyl Ketone(MIBK)), which are flammable and toxic components in order to improve the selectivity and sensitivity of dPPV/Zeolite Y and the interactions between the ketone molecules and the composites with respect to the electrical conductivity sensitivity are investigated though the infrared spectroscopy(FTTIR). All composites show definite positive responses towards the ketone vapors (Acetone, Methyl Ethyl Ketone (MEK), Methyl Iso-Buthyl Ketone (MIBK)). The electrical conductivity sensitivities of the composites increase linearly with increasing surface area of the Zeolite Y. The highest electrical conductivity sensitivity is obtained with the dPPV_/Zeolite Y (Si/Al = 5.1, NH4+), higher than those of dPPV_/Zeolite Y (Si/Al = 5.1, Na+) and dPPV_/Zeolite Y (Si/Al = 5.1, H+) when exposed to acetone. Amongst the Ketone vapors, acetone induces the highest electrical conductivity sensitivity, whereas MIBK induces the lowest electrical conductivity sensitivity.

Kamonsawas, Jirarat; Sirivat, Anuvat

2012-02-01

423

Optimization of Electrical Conductivity for Composite Bipolar Plates in PEM Fuel Cell  

NASA Astrophysics Data System (ADS)

Composites with high electrical conductivity are favourite candidates to replace the traditional graphite bipolar plate in polymer electrolyte membrane (PEM) fuel cell. Efforts to develop these composites started with the understanding of the mechanism of electrical conduction in them. Melt compounding was adopted mainly in this work for the preparation of composite material formulations which were then compression moulded to obtain plate specimens. Polypropylene-graphite, PP/G, composites were found to have the disadvantage of relatively low electrical conductivity of only up to 7 S/cm at 80 wt.% G. Combining other conductive fillers such as carbon black (CB) increased conductivity many times. Optimization of the material and processing parameters can lead to PP/G/CB composites which meet the requirement for viable application in PEM fuel cell.

Dweiri, R.; Sahari, J.; Mousa, A.

2010-03-01

424

Electrokinetic sample transport in a microchannel with spatial electrical conductivity gradients.  

PubMed

Studies of the sample transport in a microchannel with the electrical conductivity gradient are critical to develop techniques for on-chip sample transport control. A numerical model presented in this paper, consisting of the electrical potential equation, full Navier-Stokes equation and species conservation equation, is used to simulate sample transport in a microchannel with the consideration of the conductivity gradient. There are two situations studied here, sample pumping (where sample separation is minimized by employing a high-conductivity buffer in the sample region), and sample stacking (where sample separation is expedited by using a low-conductivity buffer as the sample carrier). The effects of applied electrical potential, sample diffusion coefficient and the ratio of conductivity of the driving buffer over the sample carrying buffer are investigated by using the developed model. PMID:16125716

Ren, Carolyn L; Li, Dongqing

2005-08-25

425

Investigating Electricity: Testing for Electrical Conductivity (Conductors and Insulators) Using a Variety of Materials  

NSDL National Science Digital Library

In this lab, the students will test a variety of materials to discover which items are conductors and which items are insulators. They will discuss, classify, record data, and develop new questions relating to electricity.

426

Inertial effects on electrically conducting fluids in the presence of transverse magnetic fields: An example problem  

Microsoft Academic Search

When an electric current flowing within a conducting fluid crosses magnetic field lines, a body force is created, which may significantly affect the motion of the fluid. This paper treats the flow of a conducting fluid in a toroidal duct. A transverse magnetic field is present, and a portion of one surface of the toroidal duct serves as an electrode.

K. A. Cliffe

1998-01-01

427

Ionospheric conductivities, electric fields and currents associated with auroral substorms measured by the EISCAT radar  

Microsoft Academic Search

The conductivity changes during substorm growth, onset, and expansion phases for seven substorms occurring in the local evening sector are studied using E-region electron density profiles measured by the EISCAT incoherent scatter radar. All-sky photographs and images from the Viking satellite are used to identify auroral features. Conductances and electric fields in the zone of diffuse aurora corresponding to the

Sheila Kirkwood; Hermann Opgenoorth; J. S. Murphree

1988-01-01

428

Vertex corrections to the electrical conductivity in models with elastically scattered electrons  

NASA Astrophysics Data System (ADS)

We study quantum coherence of elastically scattered lattice fermions. We calculate vertex corrections to the electrical conductivity of electrons scattered either on thermally equilibrated or statically distributed random impurities. We demonstrate that the sign of the vertex corrections to the Drude conductivity is in both cases negative. Quantum coherence due to elastic back scatterings always leads to diminution of diffusion.

Janiš, V.; Pokorný, V.

2010-04-01

429

Multi-organ effects of Conducted Electrical Weapons (CEW) — A review  

Microsoft Academic Search

Since the introduction of the Conducted Electrical Weapons (CEW) several studies have been conducted and multiple reports have been published on safety of these devices from a medical point of view. Use of these devices in different situations and reported deaths attracts media attention and causes general anxiety around these devices. These devices have several limitations- such as rate of

Mazda Biria; Sudharani Bommana; Mark Kroll; Dorin Panescu; Dhanunjaya Lakkireddy

2010-01-01

430

Effects of molecular structure on electrical conduction in low-density polyethylene above its melting point  

Microsoft Academic Search

The electrical conduction of various kinds of low-density polyethylene (LDPE) has been studied above the melting point. LDPEs are characterized by the amount and types of branches, double bonds, and oxygen-containing groups. Two components of conduction currents were found: one obeyed Ohm's law in the low field range and the other was proportional to the square of the field at

K. Iida; J. S. Kim; S. Nakamura; G. Sawa

1992-01-01

431

Effect of the onset of southwest monsoon on the atmospheric electric conductivity over the Arabian Sea  

Microsoft Academic Search

Measurements of the atmospheric electric conductivity and small, intermediate, and large ion concentrations made at four locations over the Arabian Sea onboard ORV Sagarkanya in the premonsoon and monsoon seasons during the Arabian Sea Monsoon Experiment in 2002–2003 are reported. Observations show a threefold increase in the daily average value of conductivity over a period of ?10 days preceding the

S. D. Pawar; Devendraa Siingh; V. Gopalakrishnan; A. K. Kamra

2005-01-01

432

Effect of the onset of southwest monsoon on the atmospheric electric conductivity over the Arabian Sea  

Microsoft Academic Search

Measurements of the atmospheric electric conductivity and small, intermediate, and large ion concentrations made at four locations over the Arabian Sea onboard ORV Sagarkanya in the premonsoon and monsoon seasons during the Arabian Sea Monsoon Experiment in 2002-2003 are reported. Observations show a threefold increase in the daily average value of conductivity over a period of ~10 days preceding the

S. D. Pawar; Devendraa Siingh; V. Gopalakrishnan; A. K. Kamra

2005-01-01

433

Correlation between Electrical Conductivity and Total Dissolved Solids in Natural Waters  

Microsoft Academic Search

The study aims at establishing the correlation ratio between Total Dissolved Solids (TDS )and Electrical Conductivity ( EC ) for natural waters such as fresh water , sea water and tender coconut .The EC value can be obtained from in situ conductivity measurements since it is quick reliable and relatively of low cost . Twenty four fresh water , fifteen

S. Thirumalini; Kurian Joseph

2009-01-01

434

Electrical Contact Resistance Theory for Anisotropic Conductive Films Considering Electron Tunneling and Particle Flattening  

Microsoft Academic Search

This study models the electrical contact resistance (ECR) between two surfaces separated by an anisotropic conductive film. The film is made up of an epoxy with conductive spherical particles(metallic) dispersed within. In practical situations the particles are often heavily loaded and will undergo severe plastic deformation and may essentially be flattened out. In between the particles and the surfaces there

Robert L. Jackson; Lior Kogut

2007-01-01

435

Voltage-gated cation conductance channel from fragmented sarcoplasmic reticulum: Steady-state electrical properties  

Microsoft Academic Search

Summary The interaction of fragmented sarcoplasmic reticulum (SR) with an artificial planar phospholipid membrane under conditions known to induce fusion of phospholipid vesicles raises the conductance of the planar bilayer by several orders of magnitude. Measurements of steady-state electrical properties of bilayers thus modified by SR show that two types of conductance pathways are present. One is a voltage-independent pathway

Christopher Miller

1978-01-01

436

Estimating the electrical conductivity of cement paste pore solutions from OH ?, K + and Na + concentrations  

Microsoft Academic Search

A proposed method for estimating the electrical conductivity of cement paste pore solution at 25 °C is based on the concentrations of OH?, K+ and Na+. The approach uses an equation that is a function of the solution ionic strength, and requires a single coefficient for each ionic species. To test the method, the conductivity of solutions containing mixtures of

K. A. Snyder; X. Feng; B. D. Keen; T. O. Mason

2003-01-01

437

Electrical and morphological properties of PP and PET conductive polymer fibers  

Microsoft Academic Search

Conductive fibers were obtained using two experimental processes (melt spinning and coating process). In melt spinning process, polyaniline (PANI), polypyrrole (PPy) and graphite were used in order to obtain conductive polypropylene (PP) based fibers with specific electrical and mechanical properties. PANI was treated using dodecylbenzene sulfonic acid (DBSA) to improve the solubility and the dispersion of PANI in xylene. PANI

Bohwon Kim; Vladan Koncar; Eric Devaux; Claude Dufour; Pierre Viallier

2004-01-01

438

Measurement of the electrical conductivity of metallic tubes by studying magnetic screening at low frequency  

NASA Astrophysics Data System (ADS)

We discuss a technique for measuring the electrical conductivity in metallic tubes based on Faraday's induction law. A detailed study of magnetic screening in the low frequency approximation leads to expressions that relate the screening coefficient to the geometry, magnetic permeability, and conductivity of the metallic tubes. We discuss experimental results for different tubes.

Íñiguez, J.; Raposo, V.; Flores, A. G.; Zazo, M.; Hernández-López, A.

2005-03-01

439

INFLUENCE OF MASHED POTATO DIELECTRIC PROPERTIES AND CIRCULATING WATER ELECTRIC CONDUCTIVITY ON RADIO FREQUENCY HEATING  

Microsoft Academic Search

Experiments and computer simulations were conducted to systematically investigate the influence of mashed potato dielectric properties and circulating water electric conductivity on electromagnetic field distribution, heating rate, and heating pattern in packaged food during radio frequency (RF) heating processes in a 6 kW, 27 MHz laboratory scale RF heating system. Both experimental and simulation results indicated that for the selected

Jian Wang; Robert G. Olsen; Juming Tang; Zhongwei Tang

440

Use of fathometers and electrical-conductivity probes to monitor riverbed scour at bridge piers  

USGS Publications Warehouse

Two methods, a fathometer system and an electrical- conductivity probe system, were developed to monitor scour at bridge piers. The scour-monitoring systems consisted of a sensor (fathometer or electrical- conductivity probe), power supply, data logger, relay, and system program. The fathometer system was installed and tested at a bridge over the Leipsic River at Leipsic, Delaware, and at a bridge over Sinepuxent Bay near Ocean City. Maryland. Field data collected indicate that fathometers can be used to identify and monitor the riverbed elevation if post processing of the data and trends in the data are used to determine the riverbed location in relation to the transducer. The accuracy of the system is approximately the same as the resolution of the fathometer. Signal scatter can be a major source of error in the data. The electrical- conductivity probe system was installed and tested at a bridge over the Pamunkey River near Hanover, Virginia. The approximate elevation of the riverbed is determined by comparing conductivities of the surface-water flow with conductivities of submerged bed material from sensors located in each. Field data collected indicate that an electrical- conductivity probe, as tested, has limited usefulness in identifying and monitoring the riverbed elevation during high flows. As the discharge increases, the concentration of sediment in the surface-water flow increases, especially near the riverbed. Conductivities, measured at the sensors in the surface-water flow could not be distinguished from conductivities measured at the shallowest sensor in the submerged bed material.

Hayes, D. C.; Drummond, F. E.

1995-01-01

441

Working hypothesis to explore novel wide band gap electrically conducting amorphous oxides and examples  

Microsoft Academic Search

A working hypothesis for exploring optically transparent and electrically conducting amorphous oxides is proposed on the basis of simple considerations concerning chemical bonding. The hypothesis predicts that amorphous oxides composed of heavy metal cations with an electronic configuration of (n ? 1)d10ns0 may be converted into transparent conducting amorphous oxides when doped by Li ion implantation or heating at temperatures

Hideo Hosono; Naoto Kikuchi; Naoyuki Ueda; Hiroshi Kawazoe

1996-01-01

442

Electrical-impedance spectroscopy of sedimentary rocks: prediction of hydraulic conductivity and soil water retention curves  

Microsoft Academic Search

The broadband electrical-impedance response of rocks and soils is a complex function of the pore solution chemistry, the sample microgeometry, and the surface chemical properties of the system. The conductivity and dielectric responses, which are obtained from impedance measurements, are also strong functions of the measurement frequency. The dispersion in the conductivity and dielectric responses is controlled by physiochemical polarization

D. Lesmes

2003-01-01

443

Electrical conductivity and photoluminescence of diamond films grown by downstream microwave plasma CVD  

SciTech Connect

Electrical conductivity measurements and photoluminescence (PL) were used to study the effects that sample distance from the plasma during growth has on the carrier transport properties of undoped CVD diamond. The films were grown by downstream microwave plasma chemical vapor deposition at distances from 0.5 to 2.0 cm from the edge of plasma glow. Electrical conductivity measurements were performed between room temperature and 1000[degree] C and then complimented with Raman spectroscopy and PL studies in an attempt to gain a better understanding of the CVD growth process and the resulting electrical and optical properties of the diamond films. Room temperature electrical conductivity was found to vary by over 5 orders of magnitude with increasing growth distance from the plasma, while only moderate changes were observed in the luminescence spectra. 15 refs., 9 figs.

Stoner, B.R.; Glass, J.T.; Bergman, L.; Nemanich, R.J. (North Carolina State Univ., Raleigh, NC (United States)); Zoltal, L.D.; Vandersande, J.W. (California Inst. of Technology, Pasadena, CA (United States))

1992-06-01

444

Field and temperature dependence of the small polaron hopping electrical conductivity in 1D disordered systems.  

PubMed

We investigate the effect of the electric field and the temperature on the electrical conductivity of one-dimensional disordered systems due to phonon assisted hopping of small polarons. The microscopic transport mechanism is treated within the framework of the generalized molecular crystal model and the Kubo formula, while percolation theoretical arguments lead to analytical expressions for the macroscopic behavior of the electrical conductivity at high (multi-phonon assisted hopping) and low (few-phonon assisted hopping) temperatures under the influence of moderate electric fields. The theoretical results are successfully applied to recent experimental findings for a wide temperature range and from low up to moderate electric fields. Comparison is made with other theories. PMID:21832371

Triberis, G P; Dimakogianni, M

2009-08-27

445

Electronmagnetic induction probe calibration for electrical conductivity measurements and moisture content determination of Hanford high level waste  

SciTech Connect

Logic of converting EMI measured electrical conductivity to moisture with expected uncertainty. Estimates from present knowledge, assumptions, and measured data. Archie`s Law has been used since the 1940`s to relate electrical conductivity in porous media to liquid volume fraction. Measured electrical conductivity to moisture content uses: Porosity, Interstitial liquid electrical conductivity, Solid particle density,Interstitial liquid density, and interstitial liquid water content. The uncertainty of assumed values is calculated to determine the final moisture wt.% result uncertainty.

Wittekind, W.D., Westinghouse Hanford

1996-05-23

446

Electronmagnetic induction probe calibration for electrical conductivity measurements and moisture content determination of Hanford high level waste  

Microsoft Academic Search

Logic of converting EMI measured electrical conductivity to moisture with expected uncertainty. Estimates from present knowledge, assumptions, and measured data. Archie`s Law has been used since the 1940`s to relate electrical conductivity in porous media to liquid volume fraction. Measured electrical conductivity to moisture content uses: Porosity, Interstitial liquid electrical conductivity, Solid particle density,Interstitial liquid density, and interstitial liquid water

Wittekind; Westinghouse Hanford

1996-01-01

447

On the dielectric relaxation of biological cell suspensions: the effect of the membrane electrical conductivity.  

PubMed

Due to the mismatch of the electrical parameters (the permittivity ?' and the electrical conductivity ?) of the membrane of a biological cell with the ones of the cytosol and the extracellular medium, biological cell suspensions are the site, under the influence of an external electric field, of large dielectric relaxations in the radiowave frequency range. However, a point still remains controversial, i.e., whether or not the value of membrane conductivity ?(s) might be extracted from the de-convolution of the dielectric spectra or otherwise if it would be more reasonable to assign to the membrane conductivity a value equal to zero. This point is not to be considered with superficiality since it concerns an a priori choice which ultimately influences the values of the electrical parameters deduced from this technique. As far as this point is concerned, the opinion of the researchers in this field diverges. We believe that, at least within certain limits, the membrane conductivity can be deduced from the shape of the relaxation spectra. We substantiate this thesis with two different examples concerning the first a suspension of human normal erythrocyte cells and the second a suspension of human lymphocyte cells. In both cases, by means of an accurate fitting procedure based on the Levenberg-Marquardt method for complex functions, we can evaluate the membrane conductivity ?(s) with its associated uncertainty. The knowledge of the membrane electrical conductivity will favor the investigation of different ion transport mechanisms across the cell membrane. PMID:21334862

Di Biasio, A; Cametti, C

2011-02-02

448

Development of a high pressure electrical conductivity probe for experimental studies of gas hydrates in electrolytes  

NASA Astrophysics Data System (ADS)

We previously reported the development of a high pressure automated lag time apparatus and a high pressure video cell for experimental study of nucleation and growth of gas hydrates. Here we report the development of a high pressure electrical conductivity probe that monitors the electrical conductivity of an electrolyte that is subjected to a linear cooling ramp at elevated hydrate-forming-gas pressures. The electrical conductivity steadily decreases as the linear cooling progresses because of the increasing viscosity of the electrolyte and the consequently decreasing mobility of the ions. The onset of the formation of methane-propane mixed gas hydrate films at the gas-electrolyte interface is marked by an upward spike in the electrical conductivity. The physical mechanisms behind this phenomenon remain to be elucidated. Continued cooling of the electrolyte to, and subsequent holding of, the temperature at 273 K eventually results in decreased electrical conductivity. This conductivity signal can be used for the detection of the onset of the formation of gas hydrates in optically opaque samples that contain electrolytes.

Maeda, Nobuo

2013-01-01

449

Development of a high pressure electrical conductivity probe for experimental studies of gas hydrates in electrolytes.  

PubMed

We previously reported the development of a high pressure automated lag time apparatus and a high pressure video cell for experimental study of nucleation and growth of gas hydrates. Here we report the development of a high pressure electrical conductivity probe that monitors the electrical conductivity of an electrolyte that is subjected to a linear cooling ramp at elevated hydrate-forming-gas pressures. The electrical conductivity steadily decreases as the linear cooling progresses because of the increasing viscosity of the electrolyte and the consequently decreasing mobility of the ions. The onset of the formation of methane-propane mixed gas hydrate films at the gas-electrolyte interface is marked by an upward spike in the electrical conductivity. The physical mechanisms behind this phenomenon remain to be elucidated. Continued cooling of the electrolyte to, and subsequent holding of, the temperature at 273 K eventually results in decreased electrical conductivity. This conductivity signal can be used for the detection of the onset of the formation of gas hydrates in optically opaque samples that contain electrolytes. PMID:23387698

Maeda, Nobuo

2013-01-01

450

Electrical conductivities of aluminum, copper, and tungsten observed by an underwater explosion  

SciTech Connect

Conductivities of dense aluminum, copper, and tungsten are evaluated using exploding wire discharges in water. Evolutions of the radius and the electrical resistance of exploding wire are measured together with direct pyrometric estimation of the temperature. The conductivities are evaluated based on the measurements and their density dependence is compared with theoretical predictions at a fixed temperature. The results indicate that regardless of materials, the conductivity has a minimum around 3% of solid density at temperature of 5000 K.

Sasaki, Toru [Department of Electrical Engineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka, Niigata 940-2188 (Japan); Nakajima, Mitsuo; Kawamura, Tohru; Horioka, Kazuhiko [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8502 (Japan)

2010-08-15

451

Electrically Conductive Space-Durable Polymeric Films for Spacecraft Thermal and Charge Control  

Microsoft Academic Search

There is a significant requirement for an electrically conductive thermal control film for the dissipation of spacecraft charging. The present state-of-the-art technology for charge control is based upon thin vapour-deposited indium tin oxide (ITO) conductive coatings on Teflon or Kapton films. These ITO coated films suffer from a range of problems, including no bulk conductivity, poor space durability and a

John Lennhoff; George Harris; Jason Vaughn; David Edwards; James Zwiener

1999-01-01

452

Reliability of Mutil-Layer ceramic capacitor and its conduction mechanism under high electric field  

Microsoft Academic Search

The temperature-dependent DC conduction mechanism in BaTiO3-based multilayer ceramic capacitors has been discussed in this paper. In the high electric field, BaTiO3- based Multi-Layer Ceramic Capacitor (MLCC) showed different DC conduction mechanism in room-temperature, Curie- temperature, and high-temperature regions. The DC conduction mechanisms at room and high temperature are Schottky effect and ionic flow, respectively. However, the mechanism at Curie

Yudong Lu; Yunfei En; Ming Wan; Xin Wang

2011-01-01

453

Nonlinear conductivity of lower-hybrid-wave heated plasma in the presence of an electric field  

Microsoft Academic Search

A new conductivity for lower-hybrid-wave heated plasmas is derived. This induced conductivity shows a nonlinear behavior in the presence of an electric field and can represent the plasma as an active element. The role of runaway electrons produced is important on this nonlinear conductivity. The new expression may be important for radio frequency current drive ramp-up and current drive efficiency

E. Farshi; K. N. Sato

2001-01-01

454

Relative contribution of ionospheric conductivity and electric field to the auroral electrojets  

SciTech Connect

Data from continuous scans of the Chatanika radar beam along the magnetic meridian plane are used to the determine the latitudinal profile of height-integrated ionospheric conductivities and horizontal electric fields, from which the latitudinal distribution of ionospheric currents is deduced. The observations cover invariant latitudes between 62/sup 0/ and 68/sup 0/, where the IMS Alaska meridian chain of magnetometers was also in operation. Although the conductivities and the electric fields are interrelated, the relative importance of the two in driving the eastward and westward auroral electrojet currents can be assessed. It is found that for moderate and large current densities (i.e., > or approx. =0.2 A/m), the northward electric field strength increases as the magnitude of the eastward electrojet in the evening sector increases. The height-integrated Hall conductivity stays generally at the level of 10 mhos even when the current density becomes as large as 1 A/m. However, when the eastward electrojet is small, substantial electric fields of 10-20 mV/m may still exist as if the magnetosphere has a persistent voltage source. There appear to be two distinct components to the westward electrojet. In the midnight and early morning sestors (>0300 MLT) intensity is characterized by a weak southward electric field and a high Hall conductivity, whereas its late morning portion (>0300 MLT) is dominated by a strong southward electric field.

Kamide, Y.; Vickrey, J.F.

1983-10-01

455

Upper mantle electrical conductivity for seven subcontinental regions of the Earth  

USGS Publications Warehouse

Spherical harmonic analysis coefficients of the external and internal parts of the quiet-day geomagnetic field variations (Sq) separated for the 7 continental regions of the observatories have been used to determine conductivity profiles to depths of about 600 km by the Schmucker equivalent substitute conductor method. The profiles give evidence of increases in conductivity between about 150 and 350 km depth, then a general increase in conductivity thereafter. For South America we found a high conductivity at shallow depths. The European profile showed a highly conducting layer near 125 km. At the greater depths, Europe, Australia and South America had the lowest values of conductivity. North America and east Asia had intermediate values whereas the African and central Asian profiles both showed the conductivities rising rapidly beyond 450 km depth. The regional differences indicate that there may be considerable lateral heterogeneity of electrical conductivity in the Earth's upper mantle. -Authors

Campbell, W. H.; Schiffmacher, E. R.

1988-01-01

456

Nerve Conduction Block Using Combined Thermoelectric Cooling and High Frequency Electrical Stimulation  

PubMed Central

Conduction block of peripheral nerves is an important technique for many basic and applied neurophysiology studies. To date, there has not been a technique which provides a quickly initiated and reversible “on-demand” conduction block which is both sustainable for long periods of time and does not generate activity in the nerve at the onset of the conduction block. In this study we evaluated the feasibility of a combined method of nerve block which utilizes two well established nerve blocking techniques in a rat and cat model: nerve cooling and electrical block using high frequency alternating currents (HFAC). This combined method effectively makes use of the contrasting features of both nerve cooling and electrical block using HFAC. The conduction block was initiated using nerve cooling, a technique which does no