Science.gov

Sample records for continuous electrical conductivity

  1. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Allen, Philip B.

    1979-01-01

    Examines Drude's classical (1900) theory of electrical conduction, details the objections to and successes of the 1900 theory, and investigates the Quantum (1928) theory of conduction, reviewing its successes and limitations. (BT)

  2. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  3. Electrically conductive cellulose composite

    DOEpatents

    Evans, Barbara R.; O'Neill, Hugh M.; Woodward, Jonathan

    2010-05-04

    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  4. Electrically conductive diamond electrodes

    DOEpatents

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

    2009-05-19

    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.

  5. Polymers that Conduct Electricity.

    ERIC Educational Resources Information Center

    Edelson, Edward

    1983-01-01

    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…

  6. Electrically conductive composite material

    DOEpatents

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

    1989-01-01

    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.

  7. Electrically conductive composite material

    DOEpatents

    Clough, R.L.; Sylwester, A.P.

    1989-05-23

    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 consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

  8. Electrically conductive composite material

    DOEpatents

    Clough, R.L.; Sylwester, A.P.

    1988-06-20

    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 consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

  9. Electrically conductive material

    DOEpatents

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

    1993-09-07

    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.

  10. Electrically conductive material

    DOEpatents

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

    1993-01-01

    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.

  11. Continuous production of conducting polymer

    E-print Network

    Gaige, Terry A. (Terry Alden), 1981-

    2004-01-01

    A device to continuously produce polypyrrole was designed, manufactured, and tested. Polypyrrole is a conducting polymer which has potential artificial muscle applications. The objective of continuous production was to ...

  12. Electrical Conductivity in Textiles

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Copper is the most widely used electrical conductor. Like most metals, though, it has several drawbacks: it is heavy, expensive, and can break. Fibers that conduct electricity could be the solutions to these problems, and they are of great interest to NASA. Conductive fibers provide lightweight alternatives to heavy copper wiring in a variety of settings, including aerospace, where weight is always a chief concern. This is an area where NASA is always seeking improved materials. The fibers are also more cost-effective than metals. Expenditure is another area where NASA is always looking to make improvements. In the case of electronics that are confined to small spaces and subject to severe stress, copper is prone to breaking and losing connection over time. Flexible conductive fibers eliminate that problem. They are more supple and stronger than brittle copper and, thus, find good use in these and similar situations. While clearly a much-needed material, electrically conductive fibers are not readily available. The cost of new technology development, with all the pitfalls of troubleshooting production and the years of testing, and without the guarantee of an immediate market, is often too much of a financial hazard for companies to risk. NASA, however, saw the need for electrical fibers in its many projects and sought out a high-tech textile company that was already experimenting in this field, Syscom Technology, Inc., of Columbus, Ohio. Syscom was founded in 1993 to provide computer software engineering services and basic materials research in the areas of high-performance polymer fibers and films. In 1999, Syscom decided to focus its business and technical efforts on development of high-strength, high-performance, and electrically conductive polymer fibers. The company developed AmberStrand, an electrically conductive, low-weight, strong-yet-flexible hybrid metal-polymer YARN.

  13. Electric field variations measured continuously in free air over a conductive thin zone in the tilted Lias-epsilon black shales near Osnabrück, Northwest Germany

    NASA Astrophysics Data System (ADS)

    Gurk, M.; Bosch, F. P.; Tougiannidis, N.

    2013-04-01

    Common studies on the static electric field distribution over a conductivity anomaly use the self-potential method. However, this method is time consuming and requires nonpolarizable electrodes to be placed in the ground. Moreover, the information gained by this method is restricted to the horizontal variations of the electric field. To overcome the limitation in the self-potential technique, we conducted a field experiment using a non conventional technique to assess the static electric field over a conductivity anomaly. We use two metallic potential probes arranged on an insulated boom with a separation of 126 cm. When placed into the electric field of the free air, a surface charge will be induced on each probe trying to equalize with the potential of the surrounding atmosphere. The use of a plasma source at both probes facilitated continuous and quicker measurement of the electric field in the air. The present study shows first experimental measurements with a modified potential probe technique (MPP) along a 600-meter-long transect to demonstrate the general feasibility of this method for studying the static electric field distribution over shallow conductivity anomalies. Field measurements were carried out on a test site on top of the Bramsche Massif near Osnabrück (Northwest Germany) to benefit from a variety of available near surface data over an almost vertical conductivity anomaly. High resolution self-potential data served in a numerical analysis to estimate the expected individual components of the electric field vector. During the experiment we found more anomalies in the vertical and horizontal components of the electric field than self-potential anomalies. These contrasting findings are successfully cross-validated with conventional near surface geophysical methods. Among these methods, we used self-potential, radiomagnetotelluric, electric resistivity tomography and induced polarization data to derive 2D conductivity models of the subsurface in order to infer the geometrical properties and the origin of the conductivity anomaly in the survey area. The presented study demonstrates the feasibility of electric field measurements in free air to detect and study near surface conductivity anomalies. Variations in Ez correlate well with the conductivity distribution obtained from resistivity methods. Compared to the self-potential technique, continuously free air measurements of the electric field are more rapid and of better lateral resolution combined with the unique ability to analyze vertical components of the electric field which are of particular importance to detect lateral conductivity contrasts. Mapping Ez in free air is a good tool to precisely map lateral changes of the electric field distribution in areas where SP generation fails. MPP offers interesting application in other geophysical techniques e.g. in time domain electromagnetics, DC and IP. With this method we were able to reveal a ca. 150 m broad zone of enhanced electric field strength.

  14. Continuous Measurements of Electrical Conductivity and Viscosity of Lherzorite Analogue Samples during Slow Increases and Decreases in Temperature: Melting and Pre-melting Effects

    NASA Astrophysics Data System (ADS)

    Sueyoshi, K.; Hiraga, T.

    2014-12-01

    It has been considered that transport properties of the mantle (ex. electrical conductivity, viscosity, seismic attenuation) changes dramatically during ascend of the mantle especially at around the mantle solidus. To understand the mechanism of such changes, we measured the electrical conductivity and viscosity of the lherzorite analogues during slow increases and decreases in temperature reproducing the mantle crossing its solidus. Two types of samples, one was forsterite plus 20% diopside and the other was 50% forsterite, 40% enstatite and 10% diopside with addition of 0.5% spinel, were synthesized from Mg(OH)2, SiO2, CaCO3 and MgAl2O4 (spinel) powders with particle size of <50 nm. Samples were expected to exhibit different manners in initiation of partial melt and amount of melt during the temperature change. We continuously measured electrical conductivity of these samples at every temperature during gradual temperature change, which crosses the sample solidus (~1380? and 1230? for forsterite + diopside sample and spinel-added samples, respectively). Sample viscosity were also measured under constant loads of 0.5~50 MPa. The electrical conductivity and viscosity at well below (>150?) the sample solidus exhibited linear distributions in their Arrhenius plots indicating that a single mechanism controls for each transport property within the experimental temperature ranges. Such linear relationship especially in the electrical conductivity was no longer observed at higher temperature regime exhibiting its exponential increase until the temperature reached the sample solidus. Such dramatic change with changing temperature has not been detected for the sample viscosity. Monotonic increase of electrical conductivity in accordance with increasing melt fraction was observed above the sample solidus.

  15. Electrical conduction in olivine

    SciTech Connect

    Schock, R. N.; Duba, A. G.; Shankland, T. J.

    1989-05-10

    This paper reports detailed measurements of electrical conductivitysigma and thermoelectric effect /ital S/ in the mineral olivine and in syntheticforsterite as functions of temperature in the range from 1000/degree/ to1500 /degree/C and oxygen partial pressure in the range from 10/sup /minus/10/ to10/sup 4/ Pa. The two most striking observations are strong conductivityanisotropy in forsterite and a sign change in /ital S/ in olivine at 1390 /degree/C.These results are interpreted to show that both materials have mixed ionic andextrinsic electronic conduction under these conditions. On the basis ofthese interpretations, we infer that forsterite conductivity is dominatedby electronic conduction in the /ital a/ and /ital b/ directions and probably bymovement involving magnesium vacancies in the /ital c/ direction, wherefar higher /ital P//sub O/sub 2//-independent conductivity is observed. Olivineappears to show mixed conduction under all the circumstances observed; at low temperature, electron holes dominate but are superseded bymagnesium vacancies at high temperatures./copyright/ American Geophysical Union 1989

  16. Electrically Conductive Porous Membrane

    NASA Technical Reports Server (NTRS)

    Burke, Kenneth Alan (Inventor)

    2014-01-01

    The present invention relates to an electrically conductive membrane that can be configured to be used in fuel cell systems to act as a hydrophilic water separator internal to the fuel cell, or as a water separator used with water vapor fed electrolysis cells, or as a water separator used with water vapor fed electrolysis cells, or as a capillary structure in a thin head pipe evaporator, or as a hydrophobic gas diffusion layer covering the fuel cell electrode surface in a fuel cell.

  17. Electrically conductive alternating copolymers

    DOEpatents

    Aldissi, M.; Jorgensen, B.S.

    1987-08-31

    Polymers which are soluble in common organic solvents and are electrically conductive, but which also may be synthesized in such a manner that they become nonconductive. Negative ions from the electrolyte used in the electrochemical synthesis of a polymer are incorporated into the polymer during the synthesis and serve as a dopant. A further electrochemical step may be utilized to cause the polymer to be conductive. The monomer repeat unit is comprised of two rings, a pyrrole molecule joined to a thienyl group, or a furyl group, or a phenyl group. The individual groups of the polymers are arranged in an alternating manner. For example, the backbone arrangement of poly(furylpyrrole) is -furan-pyrrole-furan-pyrrole- furan-pyrrole. An alkyl group or phenyl group may be substituted for either or both of the hydrogen atoms of the pyrrole ring.

  18. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  19. Electrically Conductive Anodized Aluminum Surfaces

    NASA Technical Reports Server (NTRS)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to < or = 10(exp 9) Omega-cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In comparison with these competing finishes, the present nanocomposite finishes are expected to cost 50 to 20 percent less and to last longer.

  20. Electrical conductivity of compressed argon

    SciTech Connect

    Bauer, R.; Windl, W.; Collins, L.; Kress, J.; Kwon, I.

    1997-10-01

    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.

  1. High temperature electrically conductive adhesives

    SciTech Connect

    Martinez, R.J.; Allen, C.; Kerr, C.; Walker, P.

    1987-06-23

    A non-proprietary electrically conductive, high-temperature adhesive has been developed. The base resin is a commercial bismaleimide resin with silver particles added to produce electrical conductivity. This adhesive has been formulated for use in our microelectronic area as a die-attach adhesive. Following a typical chip processing cycle (350/sup 0/C for one hour), the adhesive has a strength of 8.3 MPa and a volume resistivity of 10/sup -4/ ohm.cm.

  2. Calibration-free electrical conductivity measurements for highly conductive slags

    SciTech Connect

    MACDONALD,CHRISTOPHER J.; GAO,HUANG; PAL,UDAY B.; VAN DEN AVYLE,JAMES A.; MELGAARD,DAVID K.

    2000-05-01

    This research involves the measurement of the electrical conductivity (K) for the ESR (electroslag remelting) slag (60 wt.% CaF{sub 2} - 20 wt.% CaO - 20 wt.% Al{sub 2}O{sub 3}) used in the decontamination of radioactive stainless steel. The electrical conductivity is measured with an improved high-accuracy-height-differential technique that requires no calibration. This method consists of making continuous AC impedance measurements over several successive depth increments of the coaxial cylindrical electrodes in the ESR slag. The electrical conductivity is then calculated from the slope of the plot of inverse impedance versus the depth of the electrodes in the slag. The improvements on the existing technique include an increased electrochemical cell geometry and the capability of measuring high precision depth increments and the associated impedances. These improvements allow this technique to be used for measuring the electrical conductivity of highly conductive slags such as the ESR slag. The volatilization rate and the volatile species of the ESR slag measured through thermogravimetric (TG) and mass spectroscopy analysis, respectively, reveal that the ESR slag composition essentially remains the same throughout the electrical conductivity experiments.

  3. Groundwater discharge to wetlands driven by storm and flood events: Quantification using continuous Radon-222 and electrical conductivity measurements and dynamic mass-balance modelling

    NASA Astrophysics Data System (ADS)

    Gilfedder, B. S.; Frei, S.; Hofmann, H.; Cartwright, I.

    2015-09-01

    The dynamic response of groundwater discharge to external influences such as rainfall is an often neglected part of water and solute balances in wetlands. Here we develop a new field platform for long-term continuous 222Rn and electrical conductivity (EC) measurements at Sale Wetland, Australia to study the response of groundwater discharge to storm and flood events. The field measurements, combined with dynamic mass-balance modelling, demonstrate that the groundwater flux can increase from 3 to ?20 mm d-1 following storms and up to 5 mm d-1 on the receding limb of floods. The groundwater pulses are likely produced by activation of local groundwater flow paths by water ponding on the surrounding flood plains. While 222Rn is a sensitive tracer for quantifying transient groundwater discharge, the mass-balance used to estimate fluxes is sensitive to parameterisation of gas exchange (k) with the atmosphere. Comparison of six equations for calculating k showed that, based on parameterisation of k alone, the groundwater flux estimate could vary by 58%. This work shows that neglecting transient processes will lead to errors in water and solute flux estimates based on infrequent point measurements. This could be particularly important for surface waters connected to contaminated or saline groundwater systems.

  4. Electrically conductive polymer concrete coatings

    DOEpatents

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

    1988-05-26

    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.

  5. Electrically conductive polymer concrete coatings

    DOEpatents

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

    1990-03-13

    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.

  6. Electrically conductive polymer concrete coatings

    DOEpatents

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

    1990-01-01

    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.

  7. Electrically conductive polymer concrete overlays

    NASA Astrophysics Data System (ADS)

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

    1984-08-01

    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.

  8. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, Thomas E. (Grandview, MO); Spieker, David A. (Olathe, KS)

    1985-03-19

    A rigid, polyurethane foam comprises about 2-10 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.

  9. Electrically conductive rigid polyurethane foam

    DOEpatents

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

    1983-12-08

    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.

  10. Electrical Conductivity in Transition Metals

    ERIC Educational Resources Information Center

    Talbot, Christopher; Vickneson, Kishanda

    2013-01-01

    The aim of this "Science Note" is to describe how to test the electron-sea model to determine whether it accurately predicts relative electrical conductivity for first-row transition metals. In the electron-sea model, a metal crystal is viewed as a three-dimensional array of metal cations immersed in a sea of delocalised valence…

  11. Electrical conductivity of ice VII

    PubMed Central

    Okada, Taku; Iitaka, Toshiaki; Yagi, Takehiko; Aoki, Katsutoshi

    2014-01-01

    It was discovered that a peak appears near a pressure of Pc = 10?GPa in the electrical conductivity of ice VII as measured through impedance spectroscopy in a diamond anvil cell (DAC) during the process of compression from 2?GPa to 40?GPa at room temperature. The activation energy for the conductivity measured in the cooling/heating process between 278?K and 303?K reached a minimum near Pc. Theoretical modelling and molecular dynamics simulations suggest that the origin of this unique peak is the transition of the major charge carriers from the rotational defects to the ionic defects. PMID:25047728

  12. Electrical conduction through DNA molecule.

    PubMed

    Abdalla, S

    2011-09-01

    Several disorder parameters, inside the DNA molecule, lead to localization of charge carriers inside potential wells in the lowest unoccupied and highest occupied molecular orbits (LUMO and HOMO) which affects drastically the electrical conduction through the molecule, and demonstrates that the band carriers play an essential role in the conduction mechanism. So, a model is presented to shed light on the role of electrons of the LUMO in the electrical conduction through the DNA molecule. DC-, AC-conductivity and dielectric permittivity experimental data are well fitted with the presented model giving evidence that the free carriers in the LUMO and HOMO are responsible to make the DNA molecule conductor, insulator or semiconductor. The obtained results show that the localized charge carriers in the DNA molecule are characterized by four different types of relaxation phenomena which are thermally activated by corresponding four activation energies at 0.56 eV, 0.33 eV, 0.24 eV, and 0.05 eV respectively. Moreover, the calculations after the model, at room temperature, show that the time of the relaxation times of the current carriers are in the order of 5 × 10(-2)s, 1.74 × 10(-4)s, 5 × 10(-7)s, and 1.6 × 10(-10)s, respectively. PMID:21396395

  13. Electrically conductive gold nanowires on DNA scaffolds

    NASA Astrophysics Data System (ADS)

    Kundu, Subrata; Liang, Hong

    2009-08-01

    An electroless-microwave method is described here in order to synthesize electrically conductive gold nano-wires on a DNA. The electrical characterization shows that the gold wires were formed on the DNA. The nanowires were continuous, having low contact resistance, and exhibited the Ohmic behavior of electrodes. These nanowires were found to be in a few micrometers long having the diameter of 10-15 nm in solution and 20-30 nm in immobilized DNA with resistivity comparable to pure metal. The nanowires fabricated here could be used as building blocks for functional nanodevices, sensors, and optoelectronics.

  14. ELECTRICAL CONDUCTIVITY OF THE DEEP MANTLE

    E-print Network

    Cerveny, Vlastislav

    ELECTRICAL CONDUCTIVITY OF THE DEEP MANTLE Jakub Vel´imsk´y Department of Geophysics Faculty´imsk´y (CUP) Electrical conductivity of the deep mantle C2C Mari´ansk´e l´azne 2010 1 / 39 #12;Introduction Sensitivity of EMI data to 3-D conductivity in D" Conclusions J. Vel´imsk´y (CUP) Electrical conductivity

  15. Electric Conductivity of the QGP

    NASA Astrophysics Data System (ADS)

    Puglisi, Armando; Plumari, Salvatore; Greco, Vincenzo

    2015-05-01

    The transport coefficients of strongly interacting matter have attracted a great interest in the field of Quark-Gluon Plasma (QGP). In this work we compute electric conductivity ?el solving numerically the Relativistic Boltzmann Transport (RBT) equation in a uniform box with periodic boundary conditions considering 2—body scatterings. We compare numerical results obtained using two methods, Green-Kubo correlator and E-field method, with analytic formulas in Relaxation Time Approximation (RTA). We present results for the realistic case of the QGP system considering both a quasi-particle model tuned to lattice QCD thermodynamics as well as the case of a pQCD gas with a running coupling constant. Calculations based on RTA underestimate ?el of about 60%.

  16. Electrically-Conductive Polyaramid Cable And Fabric

    NASA Technical Reports Server (NTRS)

    Orban, Ralph F.

    1988-01-01

    Tows coated with metal provide strength and conductance. Cable suitable for use underwater made of electrically conductive tows of metal-coated polyaramid filaments surrounded by electrically insulating jacket. Conductive tows used to make conductive fabrics. Tension borne by metal-coated filaments, so upon release, entire cable springs back to nearly original length without damage.

  17. Electrical Conductivity of Ferritin Proteins by Conductive AFM

    NASA Technical Reports Server (NTRS)

    Xu, Degao; Watt, Gerald D.; Harb, John N.; Davis, Robert C.

    2005-01-01

    Electrical conductivity measurements were performed on single apoferritin and holoferritin molecules by conductive atomic force microscopy. Conductivity of self-assembled monolayer films of ferritin molecules on gold surfaces was also measured. Holoferritin was 5-25 times more conductive than apoferritin, indicating that for holoferritin most electron-transfer goes through the ferrihydrite core. With 1 V applied, the average electrical currents through single holoferritin and apoferritin molecules were 2.6 PA and 0.19 PA, respectively.

  18. Preparation of Electrically Conductive Polymeric Membranes

    NASA Astrophysics Data System (ADS)

    Encinas, J. C.; Castillo-Ortega, M. M.; Rodríguez, F.; Castaño, V. M.

    2015-10-01

    Cellulose acetate porous membranes, coated with polyaniline, were chemically modified with polyelectrolytes to produce films of varying and controlled porosity and electrical conductivity. The highest electrical conductivity was obtained in membranes prepared with poly(styrene sulfonate) with large pore sizes. The electrical properties as well as scanning electron microscopy (SEM) images are discussed.

  19. Dielectric constant and electrical conductivity of carbon black as an electrically conductive additive

    E-print Network

    Chung, Deborah D.L.

    Dielectric constant and electrical conductivity of carbon black as an electrically conductive) particles mixed with carbon black (CB, the most common electrically conductive additive) are reported;conductive additive used in practice is carbon black (CB) [16­ 20], although graphene, graphene oxide

  20. Electrically conductive polyimides containing silver trifluoroacetylacetonate

    NASA Technical Reports Server (NTRS)

    Rancourt, James D. (Inventor); Stoakley, Diane M. (Inventor); Caplan, Maggie L. (Inventor); St. Clair, Anne K. (Inventor); Taylor, Larry T. (Inventor)

    1996-01-01

    Polyimides with enhanced electrical conductivity are produced by adding a silver ion-containing additive to the polyamic acid resin formed by the condensation of an aromatic dianhydride with an aromatic diamine. After thermal treatment the resulting polyimides had surface conductivities in the range of 1.7.times.10.sup.-3 4.5 .OMEGA..sup.-1 making them useful in low the electronics industry as flexible, electrically conductive polymeric films and coatings.

  1. Electrically conducting polymers for aerospace applications

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Gaier, James R.; Good, Brian S.; Sharp, G. R.; Meador, Michael A.

    1991-01-01

    Current research on electrically conducting polymers from 1974 to the present is reviewed focusing on the development of materials for aeronautic and space applications. Problems discussed include extended pi-systems, pyrolytic polymers, charge-transfer systems, conductive matrix resins for composite materials, and prospects for the use of conducting polymers in space photovoltaics.

  2. Universal thermal and electrical conductivity from holography

    E-print Network

    Sachin Jain

    2010-11-15

    It is known from earlier work of Iqbal, Liu (arXiv:0809.3808) that the boundary transport coefficients such as electrical conductivity (at vanishing chemical potential), shear viscosity etc. at low frequency and finite temperature can be expressed in terms of geometrical quantities evaluated at the horizon. In the case of electrical conductivity, at zero chemical potential gauge field fluctuation and metric fluctuation decouples, resulting in a trivial flow from horizon to boundary. In the presence of chemical potential, the story becomes complicated due to the fact that gauge field and metric fluctuation can no longer be decoupled. This results in a nontrivial flow from horizon to boundary. Though horizon conductivity can be expressed in terms of geometrical quantities evaluated at the horizon, there exist no such neat result for electrical conductivity at the boundary. In this paper we propose an expression for boundary conductivity expressed in terms of geometrical quantities evaluated at the horizon and thermodynamical quantities. We also consider the theory at finite cutoff outside the horizon (arXiv:1006.1902) and give an expression for cutoff dependent electrical conductivity, which interpolates smoothly between horizon conductivity and boundary conductivity . Using the results about the electrical conductivity we gain much insight into the universality of thermal conductivity to viscosity ratio proposed in arXiv:0912.2719.

  3. Electrically conductive proppant and methods for detecting, locating and characterizing the electrically conductive proppant

    DOEpatents

    Cannan, Chad; Bartel, Lewis; Palisch, Terrence; Aldridge, David

    2015-01-13

    Electrically conductive proppants and methods for detecting, locating, and characterizing same are provided. The electrically conductive proppant can include a substantially uniform coating of an electrically conductive material having a thickness of at least 500 nm. The method can include injecting a hydraulic fluid into a wellbore extending into a subterranean formation at a rate and pressure sufficient to open a fracture therein, injecting into the fracture a fluid containing the electrically conductive proppant, electrically energizing the earth at or near the fracture, and measuring three dimensional (x, y, and z) components of electric and magnetic field responses at a surface of the earth or in an adjacent wellbore.

  4. Electrical and thermal conductivities in dense plasmas

    SciTech Connect

    Faussurier, G. Blancard, C.; Combis, P.; Videau, L.

    2014-09-15

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  5. Electrically Conductive Polyimide Films Containing Gold Surface

    NASA Technical Reports Server (NTRS)

    Caplan, Maggie L.; Stoakley, Diane M.; St. Clair, Anne K.

    1994-01-01

    Polyimide films exhibiting high thermo-oxidative stability and including electrically conductive surface layers containing gold made by casting process. Many variations of basic process conditions, ingredients, and sequence of operations possible, and not all resulting versions of process yield electrically conductive films. Gold-containing layer formed on film surface during cure. These metallic gold-containing polyimides used in film and coating applications requiring electrical conductivity, high reflectivity, exceptional thermal stability, and/or mechanical integrity. They also find commercial potential in areas ranging from thin films for satellite antennas to decorative coatings and packaging.

  6. Electrical and thermal conductivities in dense plasmas

    NASA Astrophysics Data System (ADS)

    Faussurier, G.; Blancard, C.; Combis, P.; Videau, L.

    2014-09-01

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  7. Electrical Conductivity of Shock Compressed Xenon

    NASA Astrophysics Data System (ADS)

    Mintsev, V. B.; Ternovoi, V. Ya.; Gryaznov, V. K.; Pyalling, A. A.; Fortov, V. E.

    1999-06-01

    The results on measurements of electrical conductivity of shock compressed gaseous and liquid xenon are discussed. Thermodynamic parameters of xenon are calculated in the frame of plasma chemical model. Semi-empirical equation of state was constructed for the liquid range of densities. To estimate the electrical conductivity the modified Ziman theory was used. A reasonable agreement between experimental and theoretical data on equation of state and transport properties is shown in a wide range of parameters: from gas to liquid densities, pressures 10-140 GPa and temperatures >5000K. New experimental data on measurements of equation of state and electrical conductivity of xenon under multiple shock compression are presented.

  8. Electrically Conductive White Thermal-Control Paint

    NASA Technical Reports Server (NTRS)

    Hsieh, Cheng-Hsien; Forsberg, Gustaf A.; O'Donnell, Timothy P.

    1995-01-01

    Report describes development of white thermal-control paint intended for use on spacecraft. Paint required to exhibit combination of high emittance (equal to or greater than 0.90), low absorptance (equal to or less than 0.20), and electrical conductivity sufficient to prevent charging with static electricity to potentials beyond range of plus or minus 10 V.

  9. Electrically conductive connection for an electrode

    DOEpatents

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

    1986-09-02

    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.

  10. Electrical conductivity of shock compressed xenon

    NASA Astrophysics Data System (ADS)

    Mintsev, Victor B.; Ternovoi, Vladimir Ya.; Gryaznov, Victor K.; Pyalling, Alexei A.; Fortov, Vladimir E.; Iosilevskii, Igor L.

    2000-04-01

    The results on measurements of electrical conductivity of shock compressed gaseous and liquid xenon are discussed. Thermodynamical parameters of xenon are calculated in frames of plasma chemical model. To estimate electrical conductivity modified Ziman theory is used. A reasonable agreement between experimental and theoretical data on equation of state and transport properties is shown in a wide range of parameters from gas to liquid densities, pressures 10-140 GPa and temperatures >5000 K. New experimental data on measurements of equation of state and conductivity of xenon under multiple shock compression are presented.

  11. Mechanisms of electrical conductivity in olivine

    SciTech Connect

    Schock, R.N.; Duba, A.G.; Shankland, T.J.

    1984-01-01

    Data on the electrical conductivity and the thermoelectric effect in single crystals indicate that the charge conduction mechanism in pure magnesium forsterite is electrons. The concentration of electrons can be varied by controlling the number of oxygen vacancies through manipulation of the oxygen pressure. For iron bearing olivine, the conduction mechanism is by electron holes localized on an iron ion. Since iron strongly affects the creep process as well, oxidation of iron is probably accompanied by the production of magnesium vacancies. 15 references.

  12. Making Complex Electrically Conductive Patterns on Cloth

    NASA Technical Reports Server (NTRS)

    Chu, Andrew; Fink, Patrick W.; Dobbins, Justin A.; Lin, Greg Y.; Scully, Robert C.; Trevino, Robert

    2008-01-01

    A method for automated fabrication of flexible, electrically conductive patterns on cloth substrates has been demonstrated. Products developed using this method, or related prior methods, are instances of a technology known as 'e-textiles,' in which electrically conductive patterns ar formed in, and on, textiles. For many applications, including high-speed digital circuits, antennas, and radio frequency (RF) circuits, an e-textile method should be capable of providing high surface conductivity, tight tolerances for control of characteristic impedances, and geometrically complex conductive patterns. Unlike prior methods, the present method satisfies all three of these criteria. Typical patterns can include such circuit structures as RF transmission lines, antennas, filters, and other conductive patterns equivalent to those of conventional printed circuits. The present method overcomes the limitations of the prior methods for forming the equivalent of printed circuits on cloth. A typical fabrication process according to the present method involves selecting the appropriate conductive and non-conductive fabric layers to build the e-textile circuit. The present method uses commercially available woven conductive cloth with established surface conductivity specifications. Dielectric constant, loss tangent, and thickness are some of the parameters to be considered for the non-conductive fabric layers. The circuit design of the conductive woven fabric is secured onto a non-conductive fabric layer using sewing, embroidery, and/or adhesive means. The portion of the conductive fabric that is not part of the circuit is next cut from the desired circuit using an automated machine such as a printed-circuit-board milling machine or a laser cutting machine. Fiducials can be used to align the circuit and the cutting machine. Multilayer circuits can be built starting with the inner layer and using conductive thread to make electrical connections between layers.

  13. Electrical Conductivity of Hot QCD Matter

    E-print Network

    W. Cassing; O. Linnyk; T. Steinert; V. Ozvenchuk

    2013-10-24

    We study the electric conductivity of hot QCD matter at various temperatures T within the off-shell parton-hadron-string dynamics transport approach for interacting partonic, hadronic or mixed systems in a finite box with periodic boundary conditions. The response of the strongly interacting system in equilibrium to an external electric field defines the electric conductivity sigma_0. We find a sizable temperature dependence of the ratio sigma_0/T well in line with calculations in a relaxation time approach for Tcelectric conductor than Cu or Ag (at room temperature).

  14. Electrical conductivity of an arbitrarily dense plasma

    SciTech Connect

    Rinker, G.

    1984-01-01

    This is the first of a series of papers concerning the electrical and thermal transport properties of dense plasmas. Temperatures and densities considered range from zero to 2/sup 13/ eV and 2/sup -13/ to 2/sup 13/ times compressed. In the present work we describe theoretical calculations of electrical conductivities using the t-matrix version of the Ziman theory with various self-consistent ionic potential models. The theoretical basis is described and illustrative results are given.

  15. Electrically conductive containment vessel for molten aluminum

    DOEpatents

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

    1984-06-25

    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.

  16. Continuously variable transmission: Assessment of applicability to advance electric vehicles

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Parker, R. J.

    1981-01-01

    A brief historical account of the evolution of continuously variable transmissions (CVT) for automotive use is given. The CVT concepts which are potentially suitable for application with electric and hybrid vehicles are discussed. The arrangement and function of several CVT concepts are cited along with their current developmental status. The results of preliminary design studies conducted on four CVT concepts for use in advanced electric vehicles are discussed.

  17. Electric conductivity of plasma in solar wind

    NASA Technical Reports Server (NTRS)

    Chertkov, A. D.

    1995-01-01

    One of the most important parameters in MHD description of the solar wind is the electric conductivity of plasma. There exist now two quite different approaches to the evaluation of this parameter. In the first one a value of conductivity taken from the most elaborated current theory of plasma should be used in calculations. The second one deals with the empirical, phenomenological value of conductivity. E.g.: configuration of interplanetary magnetic field, stretched by the expanding corona, depends on the magnitude of electrical conductivity of plasma in the solar wind. Knowing the main empirical features of the field configuration, one may estimate the apparent phenomenological value of resistance. The estimations show that the electrical conductivity should be approximately 10(exp 13) times smaller than that calculated by Spitzer. It must be noted that the empirical value should be treated with caution. Due to the method of its obtaining it may be used only for 'large-scale' description of slow processes like coronal expansion. It cannot be valid for 'quick' processes, changing the state of plasma, like collisions with obstacles, e.g., planets and vehicles. The second approach is well known in large-scale planetary hydrodynamics, stemming from the ideas of phenomenological thermodynamics. It could formulate real problems which should be solved by modern plasma physics, oriented to be adequate for complicated processes in space.

  18. Electrical conduction control of carbon nanowalls

    SciTech Connect

    Takeuchi, Wakana; Ura, Masato; Hori, Masaru; Hiramatsu, Mineo; Tokuda, Yutaka; Kano, Hiroyuki

    2008-05-26

    The electrical conduction behavior of carbon nanowalls (CNWs) has been evaluated by Hall measurement. CNWs, which comprise stacks of graphene sheets standing on the substrate, are fabricated by fluorocarbon/hydrogen plasma enhanced chemical vapor deposition. We have investigated the effect of N{sub 2} addition to C{sub 2}F{sub 6}/H{sub 2} system on the electrical properties of CNWs. The CNWs grown with the C{sub 2}F{sub 6}/H{sub 2} plasma exhibit p-type conduction. As a result of the nitrogen inclusion in the CNWs, the conduction type of the CNWs changes to n type. The carrier concentration is controllable by changing the flow rate of the additional N{sub 2} during the CNW growth process.

  19. Electrical conduction through linear porphyrin arrays.

    PubMed

    Yoon, Dae Hwan; Lee, Sun Bae; Yoo, K-H; Kim, Jinhee; Lim, Jong Kuk; Aratani, Naoki; Tsuda, Akihiko; Osuka, Atsuhiro; Kim, Dongho

    2003-09-10

    Electrical conduction measurements were made on two extreme types of directly linked porphyrin arrays by using nanoelectrodes. One type is the directly linked Zn(II)porphyrin arrays, consisting of 48 Zn(II)porphyrin moieties (Z48), and the other type is the completely flat, tape-shaped Zn(II)porphyrin arrays, consisting of eight Zn(II)porphyrin units (T8). The I-V curve for Z48 exhibits the diode-like behavior and the hysteresis depending on the voltage sweep direction presumably due to the conformational heterogeneity arising from the dihedral angle distribution in Z48. On the other hand, the I-V curve for T8 is nearly symmetric without any hysteresis, leading to the higher conductivity and the smaller band gap. These results illustrate that the stronger pi-electron conjugation in T8, as compared with that of Z48, results in better electrical conduction. PMID:12952488

  20. Dislocation electrical conductivity of synthetic diamond films

    SciTech Connect

    Samsonenko, S. N. Samsonenko, N. D.

    2009-05-15

    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.

  1. Electrical conductivity of a strongly coupled plasma

    SciTech Connect

    Rinker, G.A.

    1985-04-01

    This is the first in a series of papers concerning the electrical and thermal transport properties of dense plasmas. Temperatures and densities considered range approximately from room temperature to 10/sup 4/ eV and from 10/sup -4/ to 10/sup 4/ times compressed. In the present work they describe theoretical calculations of electrical conductivities using the t-matrix version of the Ziman theory with various self-consistent ionic potential models and realistic structure factors. The theoretical basis is described, and illustrative results are given.

  2. Electric conductance of highly selective nanochannels

    NASA Astrophysics Data System (ADS)

    Schnitzer, Ory; Yariv, Ehud

    2013-05-01

    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.

  3. Advanced continuously variable transmissions for electric and hybrid vehicles

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.

    1980-01-01

    A brief survey of past and present continuously variable transmissions (CVT) which are potentially suitable for application with electric and hybrid vehicles is presented. Discussion of general transmission requirements and benefits attainable with a CVT for electric vehicle use is given. The arrangement and function of several specific CVT concepts are cited along with their current development status. Lastly, the results of preliminary design studies conducted under a NASA contract for DOE on four CVT concepts for use in advanced electric vehicles are reviewed.

  4. Electrical Conduction in the Early Universe

    E-print Network

    H. Heiselberg

    1999-02-19

    The electrical conductivity has been calculated in the early universe at temperatures below as well as above the electroweak vacuum scale, $T_c\\simeq 100$GeV. Debye and dynamical screening of electric and magnetic interactions leads to a finite conductivity, $\\sigma_{el}\\sim T/\\alpha\\ln(1/\\alpha)$, at temperatures well below $T_c$. At temperatures above, $W^\\pm$ charge-exchange processes -- analogous to color exchange through gluons in QCD -- effectively stop left-handed charged leptons. However, right-handed leptons can carry current, resulting in $\\sigma_{el}/T$ being only a factor $\\sim \\cos^4\\theta_W$ smaller than at temperatures below $T_c$.

  5. Electrically conductive palladium containing polyimide films

    NASA Technical Reports Server (NTRS)

    Taylor, L. T.; St.clair, A. K.; Carver, V. C.; Furtsch, T. A. (inventors)

    1982-01-01

    Lightweight, high temperature resistant, electrically conductive, palladium containing polyimide films and methods for their preparation are described. A palladium (II) ion-containing polyamic acid solution is prepared by reacting an aromatic dianhydride with an equimolar quantity of a palladium II ion-containing salt or complex and the reactant product is cast as a thin film onto a surface and cured at approximately 300 C to produce a flexible electrically conductive cyclic palladium containing polyimide. The source of palladium ions is selected from the group of palladium II compounds consisting of LiPdCl4, PdS(CH3)2Cl2Na2PdCl4, and PdCl2. The films have application to aerodynamic and space structures and in particular to the relieving of space charging effects.

  6. Electrically conducting polyimide film containing tin complexes

    NASA Technical Reports Server (NTRS)

    St. Clair, Anne K. (Inventor); Ezzell, Stephen A. (Inventor); Taylor, Larry T. (Inventor); Boston, Harold G. (Inventor)

    1996-01-01

    Disclosed is a thermally-stable SnO.sub.2 -surfaced polyimide film wherein the electrical conductivity of the SnO.sub.2 surface is within the range of about 3.0.times.10.sup.-3 to about 1.times.10.sup.-2 ohms.sup.-1,. Also disclosed is a method of preparing this film from a solution containing a polyamic acid and SnCl.sub.4 (DMSO).sub.2.

  7. Lower Bound of Electrical Conductivity from Holography

    E-print Network

    Xian-Hui Ge; Sang-Jin Sin; Shao-Feng Wu

    2015-12-07

    We propose a universal lower bound of dc electrical conductivity in rotational- and translational- symmetries breaking systems via the holographic duality. This bound predicts that BTZ-black brane can be easily used to realize linear temperature resistivity. We also construct an anisotropic black brane solution, which yields linear temperature for the in-plane resistivity and insulating behavior for the out-of-plane resistivity. Ultimately, we discuss its implications in experiments.

  8. Lower Bound of Electrical Conductivity from Holography

    E-print Network

    Ge, Xian-Hui; Wu, Shao-Feng

    2015-01-01

    We propose a universal lower bound of dc electrical conductivity in rotational- and translational- symmetries breaking systems via the holographic duality. This bound predicts that BTZ-black brane can be easily used to realize linear temperature resistivity. We also construct an anisotropic black brane solution, which yields linear temperature for the in-plane resistivity and insulating behavior for the out-of-plane resistivity. Ultimately, we discuss its implications in experiments.

  9. Damage Detection in Electrically Conductive Structures

    NASA Astrophysics Data System (ADS)

    Anderson, Todd A.

    2002-12-01

    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.

  10. Inductive Measurement of Plasma Jet Electrical Conductivity

    NASA Technical Reports Server (NTRS)

    Turner, Matthew W.; Hawk, Clark W.; Litchford, Ron J.

    2005-01-01

    An inductive probing scheme, originally developed for shock tube studies, has been adapted to measure explosive plasma jet conductivities. In this method, the perturbation of an applied magnetic field by a plasma jet induces a voltage in a search coil, which, in turn, can be used to infer electrical conductivity through the inversion of a Fredholm integral equation of the first kind. A 1-inch diameter probe was designed and constructed, and calibration was accomplished by firing an aluminum slug through the probe using a light-gas gun. Exploratory laboratory experiments were carried out using plasma jets expelled from 15-gram high explosive shaped charges. Measured conductivities were in the range of 3 kS/m for unseeded octol charges and 20 kS/m for seeded octol charges containing 2% potassium carbonate by mass.

  11. Electrical conductivity of warm expanded aluminum

    NASA Astrophysics Data System (ADS)

    Faussurier, G.; Blancard, C.; Renaudin, P.; Silvestrelli, P. L.

    2006-05-01

    The electronic and ionic structures of warm expanded aluminum are determined self-consistently using an average-atom formalism based on density-functional theory and Gibbs Bogolyubov inequality. Ion configurations are generated using a least-square fit of the pair distribution function deduced from the average-atom model calculations. The electrical conductivity of the system is computed from the Kubo Greenwood formula for the optical conductivity implemented in a molecular dynamics scheme based on density-functional theory. This method goes beyond the Ziman approach commonly used in the average-atom formalism. Moreover, it is faster than performing ab initio molecular dynamics simulations to obtain ion configurations for the conductivity calculation. Numerical results and comparisons with experiments are presented and discussed.

  12. Electrical conductivity of warm expanded aluminum

    NASA Astrophysics Data System (ADS)

    Faussurier, Gerald; Blancard, Christophe; Renaudin, Patrick; Silvestrelli, Pier-Luigi

    2006-03-01

    The electronic and ionic structures of warm expanded aluminum are determined self-consistently using an average-atom formalism based on density-functional theory and Gibbs-Bogolyubov inequality. Ion configurations are generated using a least-square fit of the pair distribution function deduced from the average-atom model calculations. The electrical conductivity is computed from the Kubo-Greenwood formula for the optical conductivity implemented in a molecular dynamics scheme based on density-functional theory. This method goes beyond the Ziman approach used in the average-atom formalism. Moreover, it is faster than performing quantum molecular dynamics simulations to obtain ion configurations for the conductivity calculation. Numerical results and comparisons with experiments are presented and discussed.

  13. Electrical conductivity of warm expanded Al

    NASA Astrophysics Data System (ADS)

    Faussurier, G.; Blancard, C.; Renaudin, P.; Silvestrelli, P. L.

    2006-02-01

    The electronic and ionic structures of warm expanded aluminum are determined self-consistently using an average-atom formalism based on density-functional theory and Gibbs-Bogolyubov inequality. Ion configurations are generated using a least-squares fit of the pair distribution function deduced from the average-atom model calculations. The electrical conductivity is computed from the Kubo-Greenwood formula for the optical conductivity implemented in a molecular dynamics scheme based on density-functional theory. This method allows us to go beyond the Ziman approach used in the average-atom formalism. Moreover, it is faster than performing quantum molecular dynamics simulations to obtain ion configurations for the conductivity calculation. Numerical results and comparisons with experiments are presented and discussed.

  14. Electrical conductivity of warm expanded Al

    SciTech Connect

    Faussurier, G.; Blancard, C.; Renaudin, P.

    2006-02-15

    The electronic and ionic structures of warm expanded aluminum are determined self-consistently using an average-atom formalism based on density-functional theory and Gibbs-Bogolyubov inequality. Ion configurations are generated using a least-squares fit of the pair distribution function deduced from the average-atom model calculations. The electrical conductivity is computed from the Kubo-Greenwood formula for the optical conductivity implemented in a molecular dynamics scheme based on density-functional theory. This method allows us to go beyond the Ziman approach used in the average-atom formalism. Moreover, it is faster than performing quantum molecular dynamics simulations to obtain ion configurations for the conductivity calculation. Numerical results and comparisons with experiments are presented and discussed.

  15. Numerical recovery of certain discontinuous electrical conductivities

    NASA Technical Reports Server (NTRS)

    Bryan, Kurt

    1991-01-01

    The inverse problem of recovering an electrical conductivity of the form Gamma(x) = 1 + (k-1)(sub Chi(D)) (Chi(D) is the characteristic function of D) on a region omega is a subset of 2-dimensional Euclid space from boundary data is considered, where D is a subset of omega and k is some positive constant. A linearization of the forward problem is formed and used in a least squares output method for approximately solving the inverse problem. Convergence results are proved and some numerical results presented.

  16. Kinetic theory of electrical conductivity in plasmas

    SciTech Connect

    Boercker, D.B.

    1981-04-01

    A recently developed quantum kinetic theory for time-correlation functions is applied to the calculation of the electrical conductivity in dense, strongly coupled plasmas. In the weak-collision limit the theory generalizes the Ziman expression to finite temperatures while, for strong collisions, it generalizes the result of Gould and of Williams and DeWitt to include strong ion coupling. Numerical results which compare the effects that strong ion coupling, bound (core) electrons, and strong collisions have upon the collision frequency are also presented.

  17. Electrical Conductivity Calculations from the Purgatorio Code

    SciTech Connect

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

    2006-01-09

    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.

  18. Electrically-conducting thermal-control coating

    NASA Technical Reports Server (NTRS)

    Shai, M. C.

    1978-01-01

    Coating comprised mainly of zinc and aluminum oxides is characterized by high thermal emittance, low thermal absorption, and high electrical conductivity. Originally developed to protect spacecraft, coating can be used to prevent charge buildup on components in other applications. Mixture is stable under ultraviolet and X-ray radiation and under bombardment by ionizing particles. It can be applied to aluminum, stainless steel, epoxy/fiberglass, and other substrates. When exposed to equivalent of 1,000 Sun-hours illumination, coating remained stable and retained its optical properties.

  19. Electrical conductivities for hot, dense hydrogen

    SciTech Connect

    Kwon, I.; Collins, L.; Kress, J.; Troullier, N.

    1996-09-01

    We report electrical conductivities for a hydrogen plasma at temperatures between a few tenths to a few tens of electron volts and densities ranging from 0.3 to 3 g/cm{sup 3}. The ac conductivities were determined within the Kubo-Greenwood formulation based on eigenstates from a finite-temperature density functional calculation at selected time steps along a lengthy molecular-dynamics (MD) simulation trajectory. Density functional, tight-binding, and effective pair potentials were employed in the MD simulations for samples of 50 to 250 atoms within a periodically replicated reference cell. We compare with other techniques and discuss trends with density and temperature. Good agreement results at the higher temperatures and densities with generalized Ziman forms. {copyright} {ital 1996 The American Physical Society.}

  20. Electrically conductive polyurethanes for biomedical applications

    NASA Astrophysics Data System (ADS)

    Williams, Charles M.; Nash, M. A.; Poole-Warren, Laura A.

    2005-02-01

    Electrical interfacing with neural tissue poses significant problems due to host response to the material. This response generally leads to fibrous encapsulation and increased impedance across the electrode. In neural electrodes such as cochlear implants, an elastomeric material like silicone is used as an insulator for the metal electrode. This project ultimately aims to produce a polymer electrode with elastomeric mechanical properties, metal like conductivity and capability. The approach taken was to produce a nanocomposite elastomeric material based on polyurethane (PU) and carbon nanotubes. Carbon nanotubes are ideal due to their high aspect ratio as well as being a ballistic conductor. The choice of PU is based on its elastomeric properties, processability and biocompatibility. Multi-walled nanotubes (MWNTs) were dispersed ultrasonically in various dispersive solutions before being added at up to 20wt% to a 5wt% PU (Pellethane80A) in Dimethylacetamide (DMAc). Films were then solvent cast in a vacuum oven overnight. The resulting films were tested for conductivity using a two-probe technique and mechanically tested using an Instron tensiometer. The percolation threshold (p) of the PU/MWNT films occurred at loadings of between 7 and 10 wt% in this polymer system. Conductivity of the films (above p) was comparable to those for similar systems reported in the literature at up to approximately 7x10-2 Scm-1. Although PU stiffness increased with increased %loading of nanotubes, all composites were highly flexible and maintained elastomeric properties. From these preliminary results we have demonstrated electrical conductivity. So far it is evident that a superior percolation threshold is dependent on the degree of dispersion of the nanotubes. This has prompted work into investigating other preparations of the films, including melt-processing and electrospinning.

  1. Tailoring the Thermoelectric Behavior of Electrically Conductive Polymer Composites 

    E-print Network

    Moriarty, Gregory P.

    2013-05-21

    fabrication temperatures. These concerns have led research efforts into electrically conductive polymer composites prepared in ambient conditions from aqueous solutions. By combining polymer latex with carbon nanotubes (CNT), electrical conductivity can...

  2. Scaling solutions for connectivity and conductivity of continuous random networks

    NASA Astrophysics Data System (ADS)

    Galindo-Torres, S. A.; Molebatsi, T.; Kong, X.-Z.; Scheuermann, A.; Bringemeier, D.; Li, L.

    2015-10-01

    Connectivity and conductivity of two-dimensional fracture networks (FNs), as an important type of continuous random networks, are examined systematically through Monte Carlo simulations under a variety of conditions, including different power law distributions of the fracture lengths and domain sizes. The simulation results are analyzed using analogies of the percolation theory for discrete random networks. With a characteristic length scale and conductivity scale introduced, we show that the connectivity and conductivity of FNs can be well described by universal scaling solutions. These solutions shed light on previous observations of scale-dependent FN behavior and provide a powerful method for quantifying effective bulk properties of continuous random networks.

  3. Nonequilibrium Molecular Dynamics Simulation of Electric Conduction Tatsuro YUGE

    E-print Network

    Shimizu, Akira

    Nonequilibrium Molecular Dynamics Simulation of Electric Conduction Tatsuro YUGE Ã , Nobuyasu ITO1y for electric conduction, and study transport phenomena by molecular dynamics simulation. We observe. The electrical conductivity is almost independent of the impurity distribution and the system size

  4. Ionics 7 (2001) 215 Electrical Conductivity-Microstructure Correlation

    E-print Network

    Azad, Abdul-Majeed

    2001-01-01

    Ionics 7 (2001) 215 Electrical Conductivity-Microstructure Correlation in AIN-CuO Composites Abdul*-plane. A systematic variation of electrical conductivity with CuO content in the composites has been explained in the light of percolation theory. 1. Introduction High thermal conductivity along with good electrical

  5. Photovoltaic device having light transmitting electrically conductive stacked films

    DOEpatents

    Weber, Michael F. (St. Paul, MN); Tran, Nang T. (St. Paul, MN); Jeffrey, Frank R. (St. Paul, MN); Gilbert, James R. (St. Paul, MN); Aspen, Frank E. (St. Paul, MN)

    1990-07-10

    A light transmitting electrically conductive stacked film, useful as a light transmitting electrode, including a first light transmitting electrically conductive layer, having a first optical thickness, a second light transmitting layer, having a second optical thickness different from the optical thickness of the first layer, and an electrically conductive metallic layer interposed between and in initimate contact with the first and second layers.

  6. Thermal Conductivity and Elastic Constants of PEDOT:PSS with High Electrical Conductivity

    E-print Network

    Cahill, David G.

    Thermal Conductivity and Elastic Constants of PEDOT:PSS with High Electrical Conductivity Jun Liu,4-ethylenedioxythiophene) and polystyrenesulfonate (PEDOT:PSS) have high electrical conductivity when cast from aqueous component of the thermal conductivity of these highly conducting polymers is of interest for evaluating

  7. Effect of Electrical Conductivity of the Soil Solution on Stem Elongation in Fertigated

    E-print Network

    Lieth, J. Heinrich

    Effect of Electrical Conductivity of the Soil Solution on Stem Elongation in Fertigated Roses measurement · Measured as EC (electrical conductivity) · Measure continually #12;EC Probe Setup Tubing fitting;EC Probe Setup EC Meter 1234 EC probe Flask Tubing Output channels Input channels Campbell CR23X

  8. Electrical conductivity and thermopower of metallic helium

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  9. Chapter A6. Section 6.3. Specific Electrical Conductance

    USGS Publications Warehouse

    Radtke, Dean B.; Davis, Jerri V.; Wilde, Franceska D.

    2005-01-01

    Electrical conductance is a measure of the capacity of a substance to conduct an electrical current. The specific electrical conductance (conductivity) of water is a function of the types and quantities of dissolved substances it contains, normalized to a unit length and unit cross section at a specified temperature. This section of the National Field Manual (NFM) describes U.S. Geological Survey (USGS) guidance and protocols for measurement of conductivity in ground and surface waters.

  10. Electrical conductivity of thermally hydrogenated nanodiamond powders

    NASA Astrophysics Data System (ADS)

    Kondo, Takeshi; Neitzel, Ioannis; Mochalin, Vadym N.; Urai, Junichi; Yuasa, Makoto; Gogotsi, Yury

    2013-06-01

    Electrical properties of detonation diamond nanoparticles (NDs) with individual diameters of ˜5 nm are important for many applications. Although diamond is an insulator, it is known that hydrogen-terminated bulk diamond becomes conductive when exposed to water. We show that heating ND in hydrogen gas at 600-900 °C resulted in a remarkable decrease in resistivity from 107 to 105 ? cm, while the resistivity was essentially unchanged after treatment at 400 °C and lower temperatures. Fourier Transform Infrared Spectroscopy and X-ray photoelectron spectroscopy (XPS) studies revealed that hydrogenation of ND occurs at 600-900 °C, suggesting that the decrease in resistivity is based on transfer doping at the hydrogenated ND surface. Oxidation of the hydrogenated sample at 300 °C recovers resistivity to its original value. The resistivity of treated ND as a function of the O/C atomic ratio showed a transition from resistive (O/C ratio > 0.033) to conductive (O/C ratio < 0.033) state. This is consistent with the idea that the change in the resistivity is caused by the shift of the valence band maximum to above the Fermi level due to the dipole of the C-H bonds leading to transfer doping.

  11. The electrical conductivity of a pion gas

    E-print Network

    D. Fernandez-Fraile; A. Gomez Nicola

    2006-02-03

    The electrical conductivity of a pion gas at low temperatures is studied in the framework of Linear Response and Chiral Perturbation Theory. The standard ChPT power counting has to be modified to include pion propagator lines with a nonzero thermal width in order to properly account for collision effects typical of Kinetic Theory. With this modification, we discuss the relevant chiral power counting to be used in the calculation of transport coefficients. The leading order contribution is found and we show that the dominant higher order ladder diagrams can be treated as perturbative corrections at low temperatures. We find that the DC conductivity $\\sigma (T)$ is a decreasing function of $T$, behaving for very low $T$ as $\\sigma (T)\\sim e^2m_\\pi\\sqrt{m_\\pi/T}$, consistently with nonrelativistic Kinetic Theory. When unitarization effects are included, $\\sigma(T)$ increases slowly as $T$ approaches the chiral phase transition. We compare with related works and discuss some physical consequences, especially in the context of the low-energy hadronic photon spectrum in Relativistic Heavy Ion Collisions.

  12. Magnetic flowmeter for electrically conductive liquid

    DOEpatents

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

    1982-01-01

    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.

  13. Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R.

    2008-10-01

    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-?' 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-?' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.

  14. Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes

    SciTech Connect

    Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R.

    2008-10-23

    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.

  15. Role of Dislocation Movement in the Electrical Conductance of Nanocontacts

    PubMed Central

    Ishida, Tadashi; Kakushima, Kuniyuki; Mizoguchi, Teruyasu; Fujita, Hiroyuki

    2012-01-01

    Dislocation is a lattice imperfection of crystalline materials. Dislocation movement is induced during plastic deformation and influences the mechanical properties. Although the role of dislocation in mechanical properties has been well understood, the role of dislocation in electrical properties is completely lacking. Only Matthiessen's rule addresses the electrical influence of dislocations at the macroscale. Here, we show that the electrical conductance change due to dislocations and show their movements through in situ observation of a gold nanocontact. The density of the dislocations in the gold nanocontact did not affect the electrical conductance. The repeated and discrete dislocation movements resulted in an electrical conductance oscillation. Our results demonstrate how dislocations and their movements affect electric conductance at the nanoscale. This instability issue will cause a big problem for future electric devices such as ultra low power electric devices and nanowire photovoltaic devices. PMID:22953044

  16. Electrically conductive nano graphite-filled bacterial cellulose composites.

    PubMed

    Erbas Kiziltas, Esra; Kiziltas, Alper; Rhodes, Kevin; Emanetoglu, Nuri W; Blumentritt, Melanie; Gardner, Douglas J

    2016-01-20

    A unique three dimensional (3D) porous structured bacterial cellulose (BC) can act as a supporting material to deposit the nanofillers in order to create advanced BC-based functional nanomaterials for various technological applications. In this study, novel nanocomposites comprised of BC with exfoliated graphite nanoplatelets (xGnP) incorporated into the BC matrix were prepared using a simple particle impregnation strategy to enhance the thermal properties and electrical conductivity of the BC. The flake-shaped xGnP particles were well dispersed and formed a continuous network throughout the BC matrix. The temperature at 10% weight loss, thermal stability and residual ash content of the nanocomposites increased at higher xGnP loadings. The electrical conductivity of the composites increased with increasing xGnP loading (attaining values 0.75S/cm with the addition of 2wt.% of xGnP). The enhanced conductive and thermal properties of the BC-xGnP nanocomposites will broaden applications (biosensors, tissue engineering, etc.) of BC and xGnP. PMID:26572457

  17. Electrical conductivity and rheology of carbon black composites under elongation

    NASA Astrophysics Data System (ADS)

    Starý, Zden?k

    2015-04-01

    Electrical properties of conductive polymer composites are governed by filler particle structures which are formed in the material during the mixing. Therefore, knowledge of the behavior of conductive particle structures under defined conditions of deformation is necessary to produce materials with balanced electrical and rheological properties. Whereas the electrical conductivity evolution under shear can be nowadays studied even with the commercial rheometers, the investigations under elongation were not performed up to now. In this work simultaneous electrical and rheological measurements in elongation on polystyrene/carbon black composites are introduced. Such kind of experiment can help in understanding the relationships between processing conditions and properties of conductive polymer composites.

  18. Method of forming an electrically conductive cellulose composite

    DOEpatents

    Evans, Barbara R. (Oak Ridge, TN); O'Neill, Hugh M. (Knoxville, TN); Woodward, Jonathan (Ashtead, GB)

    2011-11-22

    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  19. Gas-Tolerant Device Senses Electrical Conductivity of Liquid

    NASA Technical Reports Server (NTRS)

    O'Connor, Edward W.

    2005-01-01

    The figure depicts a device for measuring the electrical conductivity of a flowing liquid. Unlike prior such devices, this one does not trap gas bubbles entrained in the liquid. Usually, the electrical conductivity of a liquid is measured by use of two electrodes immersed in the liquid. A typical prior device based on this concept contains large cavities that can trap gas. Any gas present between or near the electrodes causes a significant offset in the conductivity reading and, if the gas becomes trapped, then the offset persists. Extensive tests on two-phase (liquid/ gas) flow have shown that in the case of liquid flowing along a section of tubing, gas entrained in the liquid is not trapped in the section as long as the inner wall of the section is smooth and continuous, and the section is the narrowest tubing section along the flow path. The design of the device is based on the foregoing observation: The electrodes and the insulators separating the electrodes constitute adjacent parts of the walls of a tube. The bore of the tube is machined to make the wall smooth and to provide a straight flow path from the inlet to the outlet. The diameter of the electrode/insulator tube assembly is less than the diameter of the inlet or outlet tubing. An outer shell contains the electrodes and insulators and constitutes a leak and pressure barrier. Any gas bubble flowing through this device causes only a momentary conductivity offset that is filtered out by software used to process the conductivity readings.

  20. Proof of universality of electrical conductivity at finite chemical potential

    E-print Network

    Sayan K. Chakrabarti; Shankhadeep Chakrabortty; Sachin Jain

    2011-02-17

    It was proposed in arXiv:1008.2944 that, for certain gauge theories with gravity duals, electrical conductivity at finite chemical potential is universal. Here we provide a general proof that, when matter stress tensor satisfies a compact constraint, electrical conductivity is universal. We further elaborate our result with several conformal as well as non-conformal gauge theories. We also discuss how boundary conductivity and universal conductivity of stretched horizon are related.

  1. Electrical conductivity of segregated network polymer nanocomposites 

    E-print Network

    Kim, Yeon Seok

    2009-06-02

    A set of experiments was designed and performed to gain a fundamental understanding of various aspects of the segregated network concept. The electrical and mechanical properties of composites made from commercial latex and carbon black are compared...

  2. Synthesis of novel electrically conducting polymers: Potential conducting Langmuir-Blodgett films and conducting polymers on defined surfaces

    NASA Technical Reports Server (NTRS)

    Zimmer, Hans

    1993-01-01

    Based on previous results involving thiophene derived electrically conducting polymers in which it was shown that thiophene, 3-substituted thiophenes, furans, and certain oligomers of these compounds showed electrical conductivity after polymerization. The conductivity was in the order of up to 500 S/cm. In addition, these polymers showed conductivity without being doped and most of all they were practically inert toward ambient conditions. They even could be used in aqueous media. With these findings as a guide, a number of 3-long-chain-substituted thiophenes and 1-substituted-3-long-chain substituted pyrrols were synthesized as monomers for potential polymeric electrically conducting Langmuir-Blodgett films.

  3. Electrically conducting ternary amorphous fully oxidized materials and their application

    NASA Technical Reports Server (NTRS)

    Giauque, Pierre (Inventor); Nicolet, Marc (Inventor); Gasser, Stefan M. (Inventor); Kolawa, Elzbieta A. (Inventor); Cherry, Hillary (Inventor)

    2004-01-01

    Electrically active devices are formed using a special conducting material of the form Tm--Ox mixed with SiO2 where the materials are immiscible. The immiscible materials are forced together by using high energy process to form an amorphous phase of the two materials. The amorphous combination of the two materials is electrically conducting but forms an effective barrier.

  4. Simulation of partial discharges in conducting and non-conducting electrical tree structures

    NASA Astrophysics Data System (ADS)

    Champion, J. V.; Dodd, S. J.

    2001-04-01

    Electrical treeing is of interest to the electrical generation, transmission and distribution industries as it is one of the causes of insulation failure in electrical machines, switchgear and transformer bushings. Previous experimental investigations of electrical treeing in epoxy resins have found evidence that the tree structures formed were either electrically conducting or non-conducting, depending on whether the epoxy resin was in a flexible state (above its glass transition temperature) or in the glassy state (below its glass transition temperature). In this paper we extend an existing model, of partial discharges within an arbitrarily defined non-conducting electrical tree structure, to the case of electrical conducting trees. With the inclusion of tree channel conductivity, the partial discharge model could simulate successfully the experimentally observed partial discharge activity occurring in trees grown in both the flexible and glassy epoxy resins. This modelling highlights a fundamental difference in the mechanism of electrical tree growth in flexible and glassy epoxy resins. The much lower resistivities of the tree channels grown in the glassy epoxy resins may be due to conducting decomposition (carbonized) products condensing on the side walls of the existing channels, whereas, in the case of non-conducting tree channels, subsequent discharges within the main branches lead to side-wall erosion and a consequent widening of the tubules. The differing electrical characteristics of the tree tubules also have consequences for the development of diagnostic tools for the early detection of pre-breakdown phenomena.

  5. Electrically Conductive Multiphase Polymer Blend Carbon-Based Composites

    NASA Astrophysics Data System (ADS)

    Brigandi, Paul James

    The use of multiphase polymer blends provides unique morphologies and properties to reduce the percolation concentration and increase conductivity of carbon-based polymer composites. These systems offer improved conductivity, temperature stability and selective distribution of the conductive filler through unique morphologies at significantly lower conductive filler concentration. In this work, the kinetic and thermodynamic effects on a series of multiphase conductive polymer composites were investigated. The polymer blend phase morphology, filler distribution, electrical conductivity, and rheological properties of CB-filled PP/PMMA/EAA conductive polymer composites were determined. Thermodynamic and kinetic parameters were found to influence the morphology development and final composite properties. The morphology and CB distribution were found to be kinetically driven when annealed for a short period of time following the shear-intensive mixing process, whereas the three-phase polymer blend morphology is driven by thermodynamics when given sufficient time under high temperature annealing conditions in the melt state. At short annealing times, the CB distribution was influenced by the compounding sequence where the CB was added after being premixed with one of the polymer phases or directly added to the three phase polymer melt, but again was thermodynamically driven at longer annealing times with the CB migrating to the EAA phase. The resistivity was found to decrease by a statistically significant amount to similar levels for all of the composite systems with increasing annealing time, providing evidence of gradual phase coalescence to a tri-continuous morphology and CB migration. The addition of CB via the PP and EAA masterbatch results in significantly faster percolation and lower resistivity compared to when added direct to the system during compounding after 30 minutes annealing by a statistically significant amount. Dynamic oscillatory shear rheology using small-amplitude oscillations was used to probe for differences in the tri-continuous morphology and attempt to characterize the CB distribution with annealing time. Minor differences were observed in the PP/PMMA/(EAA-CB) as a function of annealing time, while the rheological behavior was not observed to be significantly different for the other multiphase composites as a function of annealing, nor for the compounding sequence after the same annealing time.

  6. Sintering, Microstructure, and Electrical Conductivity of Zirconia-Molybdenum Cermet

    NASA Astrophysics Data System (ADS)

    Guo, Yanling; Tang, Lei; Zhang, Jieyu

    2015-08-01

    Monolithic zirconia-molybdenum ( m-ZrO2/Mo) cermets of different compositions (5-40 vol.% Mo) and different initial Mo particles sizes (0.08-13 ?m) were prepared by traditional powder metallurgy process. The influences of metal content and initial particle sizes on the densification behavior, microstructure, and electrical conductivity of the cermets were studied. A percolation threshold value was obtained about 17.1 vol.% molybdenum fraction, above which a sharp increase in the electrical conductivity was observed. The temperature dependence of the electrical conductivity of cermets was studied. The cermet containing 5 vol.% Mo showed the ionic nature of the conductivity, while the metallic nature was observed in the samples of Mo fraction up to 16 vol.%. The activation of conductivity for ionic type of conductivity and the temperature coefficient of resistivity as well as the effect of porosity on electronic type conductivity are discussed.

  7. Electrical conductivity of wadsleyite at high temperatures and high pressures

    NASA Astrophysics Data System (ADS)

    Dai, Lidong; Karato, Shun-ichiro

    2009-09-01

    The electrical conductivity of wadsleyite aggregates has been determined under the broad range of thermodynamic conditions using the impedance spectroscopy for a frequency range of 10 - 2 to 10 6 Hz. Two branches are observed in the complex impedance, one (at high frequency range) showing a half circle originated at Z' (real part of impedance) = Z? (imaginary part of impedance) = 0 in the Z'- Z? plot, and another branch in the low frequency range. The results from high frequency semi-circles correspond to the electric properties of a sample, whereas the results from a low frequency branch correspond to the electrode effects. From the analysis of the results from the semi-circles, we have identified two distinct mechanisms of electrical conduction having different activation enthalpies and different sensitivity to oxygen fugacity and water content. One mechanism dominating at water-poor condition has a high activation enthalpy (~ 147 kJ/mol) and the conductivity increases with oxygen fugacity. We suggest that electrical conduction in this regime is due to charge transfer involving ferric iron ("polaron" conduction). Under water-rich conditions, electrical conductivity increases with water content but decreases with oxygen fugacity, and the activation enthalpy is smaller (~ 88 kJ/mol). We infer that electrical conduction in this regime is due to protons. The activation enthalpy in this regime is insensitive to water content and the conductivity is proportional to water content, CW, as ? ? Cwr with r~ 0.72. The value of r is smaller than one suggests that minority defects such as H M' or H ? are responsible for electrical conduction. Our results show that a completely dry transition zone is incompatible with most of the geophysical observations on the mantle transition zone, and some water (~ 0.1-0.3 wt.% in the Pacific) is required to explain the observed electrical conductivity.

  8. Assembly for electrical conductivity measurements in the piston cylinder device

    DOEpatents

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

    2012-06-05

    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.

  9. Ultrahigh strength and high electrical conductivity in copper.

    PubMed

    Lu, Lei; Shen, Yongfeng; Chen, Xianhua; Qian, Lihua; Lu, K

    2004-04-16

    Methods used to strengthen metals generally also cause a pronounced decrease in electrical conductivity, so that a tradeoff must be made between conductivity and mechanical strength. We synthesized pure copper samples with a high density of nanoscale growth twins. They showed a tensile strength about 10 times higher than that of conventional coarse-grained copper, while retaining an electrical conductivity comparable to that of pure copper. The ultrahigh strength originates from the effective blockage of dislocation motion by numerous coherent twin boundaries that possess an extremely low electrical resistivity, which is not the case for other types of grain boundaries. PMID:15031435

  10. Using electrical impedance tomography to map subsurface hydraulic conductivity

    DOEpatents

    Berryman, James G. (Danville, CA); Daily, William D. (Livermore, CA); Ramirez, Abelardo L. (Pleasanton, CA); Roberts, Jeffery J. (Livermore, CA)

    2000-01-01

    The use of Electrical Impedance Tomography (EIT) to map subsurface hydraulic conductivity. EIT can be used to map hydraulic conductivity in the subsurface where measurements of both amplitude and phase are made. Hydraulic conductivity depends on at least two parameters: porosity and a length scale parameter. Electrical Resistance Tomography (ERT) measures and maps electrical conductivity (which can be related to porosity) in three dimensions. By introducing phase measurements along with amplitude, the desired additional measurement of a pertinent length scale can be achieved. Hydraulic conductivity controls the ability to flush unwanted fluid contaminants from the surface. Thus inexpensive maps of hydraulic conductivity would improve planning strategies for subsequent remediation efforts. Fluid permeability is also of importance for oil field exploitation and thus detailed knowledge of fluid permeability distribution in three-dimension (3-D) would be a great boon to petroleum reservoir analysts.

  11. Electrical Switchability and Dry-Wash Durability of Conductive Textiles

    PubMed Central

    Wu, Bangting; Zhang, Bowu; Wu, Jingxia; Wang, Ziqiang; Ma, Hongjuan; Yu, Ming; Li, Linfan; Li, Jingye

    2015-01-01

    There is growing interest in the area of conductive textiles in the scientific and industrial community. Herein, we successfully prepared a conductive textile via covalently grafting polyaniline (PANI) onto cotton by a multi-step treatment process. The conductivity of the resultant fabric could be tuned by immersing in water having different pH values. The conductive and insulating properties of the textile could be conveniently switched by alternately immersing in acidic and alkaline bath solutions. Most importantly, the resultant conductive fabrics were able to withstand 40 simulated dry-wash cycles, with almost no decay in the electrical conductivity, indicating their excellent dry-wash durability. The present strategy for fabricating conductive fabrics with excellent switchability of electrical properties and dry-wash durability is expected to provide inspiration for the production of multifunctional conductive textiles for use in hash or sensitive conditions. PMID:26066704

  12. Electrical Switchability and Dry-Wash Durability of Conductive Textiles

    NASA Astrophysics Data System (ADS)

    Wu, Bangting; Zhang, Bowu; Wu, Jingxia; Wang, Ziqiang; Ma, Hongjuan; Yu, Ming; Li, Linfan; Li, Jingye

    2015-06-01

    There is growing interest in the area of conductive textiles in the scientific and industrial community. Herein, we successfully prepared a conductive textile via covalently grafting polyaniline (PANI) onto cotton by a multi-step treatment process. The conductivity of the resultant fabric could be tuned by immersing in water having different pH values. The conductive and insulating properties of the textile could be conveniently switched by alternately immersing in acidic and alkaline bath solutions. Most importantly, the resultant conductive fabrics were able to withstand 40 simulated dry-wash cycles, with almost no decay in the electrical conductivity, indicating their excellent dry-wash durability. The present strategy for fabricating conductive fabrics with excellent switchability of electrical properties and dry-wash durability is expected to provide inspiration for the production of multifunctional conductive textiles for use in hash or sensitive conditions.

  13. The effect of water on the electrical conductivity of olivine.

    PubMed

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

    2006-10-26

    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

  14. Synthesis and characterization of electrical conducting porous carbon structures based on resorcinol-formaldehyde

    NASA Astrophysics Data System (ADS)

    Najeh, I.; Ben Mansour, N.; Mbarki, M.; Houas, A.; Nogier, J. Ph.; El Mir, L.

    2009-10-01

    Electrical conducting carbon (ECC) porous structures were explored by changing the pyrolysis temperature of organic xerogel compounds prepared by sol-gel method from resorcinol-formaldehyde (RF) mixtures in acetone using picric acid as catalyst. The effect of this preparation parameter on the structural and electrical properties of the obtained ECCs was studied. The analysis of the obtained results revealed that the polymeric insulating xerogel phase was transformed progressively with pyrolysis temperature into carbon conducting phase; this means the formation of long continuous conducting path for charge carriers to move inside the structure with thermal treatment and the samples exhibited tangible percolation behaviour where the percolation threshold can be determined by pyrolysis temperature. The temperature-dependent conductivity of the obtained ECC structures shows a semi-conducting behaviour and the I( V) characteristics present a negative differential resistance. The results obtained from STM micrographs revealed that the obtained ECC structures consist of porous electrical conducting carbon materials.

  15. Software optimization for electrical conductivity imaging in polycrystalline diamond cutters

    SciTech Connect

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

    2014-02-18

    We previously reported on an electrical conductivity imaging instrument developed for measurements on polycrystalline diamond cutters. These cylindrical cutters for oil and gas drilling feature a thick polycrystalline diamond layer on a tungsten carbide substrate. The instrument uses electrical impedance tomography to profile the conductivity in the diamond table. Conductivity images must be acquired quickly, on the order of 5 sec per cutter, to be useful in the manufacturing process. This paper reports on successful efforts to optimize the conductivity reconstruction routine, porting major portions of it to NVIDIA GPUs, including a custom CUDA kernel for Jacobian computation.

  16. Software optimization for electrical conductivity imaging in polycrystalline diamond cutters

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    We previously reported on an electrical conductivity imaging instrument developed for measurements on polycrystalline diamond cutters. These cylindrical cutters for oil and gas drilling feature a thick polycrystalline diamond layer on a tungsten carbide substrate. The instrument uses electrical impedance tomography to profile the conductivity in the diamond table. Conductivity images must be acquired quickly, on the order of 5 sec per cutter, to be useful in the manufacturing process. This paper reports on successful efforts to optimize the conductivity reconstruction routine, porting major portions of it to NVIDIA GPUs, including a custom CUDA kernel for Jacobian computation.

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

    NASA Astrophysics Data System (ADS)

    Pommier, A.; Le-Trong, E.

    2011-09-01

    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.

  18. Temperature-dependent electrical conductivity of soda-lime glass

    NASA Technical Reports Server (NTRS)

    Bunnell, L. Roy; Vertrees, T. H.

    1993-01-01

    The objective of this educational exercise was to demonstrate the difference between the electrical conductivity of metals and ceramics. A list of the equipment and supplies and the procedure for the experiment are presented.

  19. Electrical conductivity of rocks at high pressures and temperatures

    NASA Technical Reports Server (NTRS)

    Parkhomenko, E. I.; Bondarenko, A. T.

    1986-01-01

    The results of studies of the electrical conductivity in the most widely distributed types of igneous rocks, at temperatures of up to 1200 C, at atmospheric pressure, and also at temperatures of up to 700 C and at pressures of up to 20,000 kg/sq cm are described. The figures of electrical conductivity, of activaation energy and of the preexponential coefficient are presented and the dependence of these parameters on the petrochemical parameters of the rocks are reviewed. The possible electrical conductivities for the depository, granite and basalt layers of the Earth's crust and of the upper mantle are presented, as well as the electrical conductivity distribution to the depth of 200 to 240 km for different geological structures.

  20. Electrical Circuit Analogues of Thermal Conduction and Diffusion

    ERIC Educational Resources Information Center

    Tomlin, D. H.; Fullarton, G. K.

    1978-01-01

    After briefly reviewing equations of conduction and diffusion, and voltage and charge in electrical circuits, a simple experiment is given that allows students practical experience in a theoretical realm of physics. (MDR)

  1. Imparting Electrical Conductivity into Asphalt Composites Using Graphite 

    E-print Network

    Baranikumar, Aishwarya

    2013-07-09

    observed. Since the percolation threshold hinders precise control of asphalt conductivity, it is imperative to mitigate the sudden transition in the electrical resistivity curve to enable practical applications of asphalt composites. Some recent...

  2. Measurement of Electrical Conductivity for a Biomass Fire

    PubMed Central

    Mphale, Kgakgamatso; Heron, Mal

    2008-01-01

    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

  3. Electrical Conductivity of the Lower-Mantle Ferropericlase

    SciTech Connect

    Lin, J F; Weir, S T; Jackson, D D; Evans, W J; Vohra, Y K; Qiu, W; Yoo, C S

    2007-04-19

    Electrical conductivity of the lower-mantle ferropericlase-(Mg{sub 0.75},Fe{sub 0.25})O has been studied using designer diamond anvils to pressures over one megabar and temperatures up to 500 K. The electrical conductivity of (Mg{sub 0.75},Fe{sub 0.25})O gradually rises by an order of magnitude up to 50 GPa but decreases by a factor of approximately three between 50 to 70 GPa. This decrease in the electrical conductivity is attributed to the electronic high-spin to low-spin transition of iron in ferropericlase. That is, the electronic spin transition of iron results in a decrease in the mobility and/or density of the charge transfer carriers in the low-spin ferropericlase. The activation energy of the low-spin ferropericlase is 0.27 eV at 101 GPa, similar to that of the high-spin ferropericlase at relatively low temperatures. Our results indicate that low-spin ferropericlase exhibits lower electrical conductivity than high-spin ferropericlase, which needs to be considered in future geomagnetic models for the lower mantle. The extrapolated electrical conductivity of the low-spin ferropericlase, together with that of silicate perovskite, at the lower mantle pressure-temperature conditions is consistent with the model electrical conductivity profile of the lower mantle.

  4. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    NASA Technical Reports Server (NTRS)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  5. DC Electrical Conductivity of Silicon Carbide Ceramics and Composites for Flow Channel Insert Applications

    SciTech Connect

    Katoh, Yutai; Kondo, Sosuke; Snead, Lance Lewis

    2009-01-01

    High purity chemically vapor-deposited silicon carbide (SiC) and 2D continuous SiC fiber, chemically vapor-infiltrated SiC matrix composites with pyrocarbon interphases were examined for temperature dependent (RT to 800 C) electrical conductivity and the influence of neutron irradiation on it. In the 2D composites, trans-thickness electrical conductivity was dominated by bypass conduction via interphase network at relatively low temperatures, whereas conduction through SiC constituents dominated at higher temperatures. The Influence of neutron irradiation on electrical properties appeared very strong for SiC, resulting typically in by orders lower ambient conductivity and steeper temperature dependency. Through-thickness electrical conductivity of neutron-irradiated 2D SiC composites with thin PyC interphase will likely in the order of 10 S/m in the typical operating temperature range for flow channel inserts. Mechanisms of electrical conduction in the composites and irradiation-induced modification of electrical conductivity of the composites and their constituents are discussed.

  6. Measurements of electrical conductivities of carbonates in the subducted slab

    NASA Astrophysics Data System (ADS)

    Ono, S.

    2012-12-01

    The behavior of carbonate minerals in the deep mantle is important in our understanding of the geochemical cycle of carbon. Magnesium and calcium carbonate minerals dominate the Earth's interior. Magnesite (MgCO3) is a naturally occurring carbonate mineral and is stable over a wide range of pressure and temperature. In contrast, calcium carbonate (CaCO3) occurs in three structural forms: calcite, aragonite, and vaterite. Calcite is stable under ambient conditions, and adopts several different modifications (calcite I-V), whereas aragonite is thermodynamically stable at high pressures and high temperature. Dolomite (MgCaC2O6) is stable up to the mantle pressures. Therefore, the behavior of magnesite, aragonite, and dolomite are important for an understanding of the circulation of carbon from the crust to the upper mantle. Recent advances in geophysical observations have allowed to map the electrical conductivity of the Earth's mantle. Electrical conductivity measurements on carbonates at high pressures and high temperatures can contribute towards an estimation of the distribution of carbonate rocks in the deep mantle. In this study, we have determined the electrical conductivities of three carbonates up to 6 GPa and 1000 K using in situ complex impedance spectroscopy in a multi-anvil high-pressure apparatus. These measurements allowed us to quantify the effects of pressure and temperature. The electrical conductivity of magnesite increased with increasing pressure. The activation enthalpy also increased with increasing pressure. The effect of pressure was interpreted as being the activation volume in the Arrhenius equation. The negative activation volume and relatively large activation energy observed in this study suggests that the hopping of large polarons is the dominant mechanism for the electrical conductivity over the pressure and temperature range investigated [1]. In the case of aragonite, a decrease in the electrical conductivity with increasing pressure was observed. The calculated activation enthalpy increased with increasing pressure. The positive activation volume observed in this study suggests that ionic conduction is the dominant mechanism over the pressure and temperature range investigated [2]. The electrical conductivity of aragonite was higher than that of magnesite. The electrical conductivity of dolomite was intermediate value between magnesite and aragonite. According to our data, the electrical conductivities of carbonates can be described as a function of pressure, temperature, and chemical composition. Our new data can contribute to interpret the electrical conductivity map of the Earth's interior. [1] Mibe & Ono (2011) Physica B, 406, 2018-2020. [2] Ono & Mibe (2012) Eur. J. Mineral. (in press).

  7. Electrostatic Discharge Sensitivity and Electrical Conductivity of Composite Energetic Materials

    SciTech Connect

    Michael A. Daniels; Daniel J. Prentice; Chelsea Weir; Michelle L. Pantoya; Gautham Ramachandran; Tim Dallas

    2013-02-01

    Composite energetic material response to electrical stimuli was investigated and a correlation between electrical conductivity and ignition sensitivity was examined. The composites consisted of micrometer particle aluminum combined with another metal, metal oxide, or fluoropolymer. Of the nine tested mixtures, aluminum with copper oxide was the only mixture to ignite by electrostatic discharge with minimum ignition energy (MIE) of 25 mJ and an electrical conductivity of 1246.25 nS; two orders of magnitude higher than the next composite. This study showed a similar trend in MIE for ignition triggered by a discharged spark compared with a thermal hot wire source.

  8. A conducting ball in an axial electric field

    E-print Network

    Alexander Savchenko

    2012-12-26

    We describe the distribution of a charge, the electric moments of arbitrary order and the force acting on a conducting ball on the axis of the axial electric field. We determine the full charge and the dipole moments of the first order for a conducting ball in an arbitrary inhomogeneous harmonic electric field. All statements are formulated in the form of theorems with proofs basing on properties of the matrix of moments of the Legendre polynomials. The analysis and proof of these properties are presented in Appendix.

  9. Scaling of the electrical conductivity of granular media

    NASA Astrophysics Data System (ADS)

    Goldobin, D. S.; Krauzin, P. V.

    2014-05-01

    We derive the scaling properties of the dependence of the macroscopic electrical conductivity of granular media (e.g., sands) with a surface mechanism of electrical conduction on the grain size, when the medium is subjected to a given mechanical stress. In order to eliminate the influence of the inter-grain junction capacity, the direct electrical current is considered. We determine the applicability restrictions on the theory which disregards the ultimate crushing compression strength, adhesion, and the effect of charge carrier tunneling at grain junctions beyond the contact surface area. Solutions for several regular packings of grains are obtained as well.

  10. Thermal conductivity, electrical conductivity and specific heat of copper-carbon fiber composite

    NASA Technical Reports Server (NTRS)

    Kuniya, Keiichi; Arakawa, Hideo; Kanai, Tsuneyuki; Chiba, Akio

    1988-01-01

    A new material of copper/carbon fiber composite is developed which retains the properties of copper, i.e., its excellent electrical and thermal conductivity, and the property of carbon, i.e., a small thermal expansion coefficient. These properties of the composite are adjustable within a certain range by changing the volume and/or the orientation of the carbon fibers. The effects of carbon fiber volume and arrangement changes on the thermal and electrical conductivity, and specific heat of the composite are studied. Results obtained are as follows: the thermal and electrical conductivity of the composite decrease as the volume of the carbon fiber increases, and were influenced by the fiber orientation. The results are predictable from a careful application of the rule of mixtures for composites. The specific heat of the composite was dependent, not on fiber orientation, but on fiber volume. In the thermal fatigue tests, no degradation in the electrical conductivity of this composite was observed.

  11. Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

    DOEpatents

    Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

    2015-07-21

    Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

  12. 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...

  13. A Structural Electrical Conductivity Model for Oxide Melts

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Jung, In-Ho

    2015-09-01

    A structural electrical conductivity model for oxide melts was developed based on the Nernst-Einstein relationship of ionic conductivity. In the description of ionic conductivity, the effective diffusivities of cations in oxide slags were described as a function of the polymerization of the melt. The polymerization of oxide melts was calculated from the Modified Quasichemical Model, taking into account the short-range ordering in slags. The parameters of this conductivity model were fixed to reproduce the electrical conductivity data in unary and binary melts, and the model can well predict the conductivity data in ternary and higher order system without any additional model parameters. The model is successfully applied to the CaO-MgO-MnO-PbO-Al2O3-SiO2 system.

  14. Electric field enhanced conductivity in strongly coupled dense metal plasma

    SciTech Connect

    Stephens, J.; Neuber, A.

    2012-06-15

    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.

  15. Electrically conductive resinous bond and method of manufacture

    DOEpatents

    Snowden, T.M. Jr.; Wells, B.J.

    1985-01-01

    A method of bonding elements together with a bond of high strength and good electrical conductivity which comprises: applying an unfilled polyimide resin between surfaces of the elements to be bonded, heat treating said unfilled polyimide resin in stages between a temperature range of about 40 to 365/sup 0/C to form a strong adhesive bond between said elements, applying a metal-filled polyimide resin overcoat between said elements so as to provide electrical connection therebetween, and heat treating said metal-filled polyimide resin with substantially the same temperature profile as the unfilled polyimide resin. The present invention is also concerned with an adhesive, resilient, substantially void free bonding combination for providing a high strength, electrically conductive adhesive attachment between electrically conductive elements which comprises a major amount of an unfilled polyimide resin and a minor amount of a metal-filled polyimide resin.

  16. Continuous-flow electrophoresis: Membrane-associated deviations of buffer pH and conductivity

    NASA Technical Reports Server (NTRS)

    Smolka, A. J. K.; Mcguire, J. K.

    1978-01-01

    The deviations in buffer pH and conductivity which occur near the electrode membranes in continuous-flow electrophoresis were studied in the Beckman charged particle electrophoresis system and the Hanning FF-5 preparative electrophoresis instrument. The nature of the membranes separating the electrode compartments from the electrophoresis chamber, the electric field strength, and the flow rate of electrophoresis buffer were all found to influence the formation of the pH and conductivity gradients. Variations in electrode buffer flow rate and the time of electrophoresis were less important. The results obtained supported the hypothesis that a combination of Donnan membrane effects and the differing ionic mobilities in the electrophoresis buffer was responsible for the formation of the gradients. The significance of the results for the design and stable operation of continuous-flow electrophoresis apparatus was discussed.

  17. Transverse electric conductivity in quantum collisional plasma in Mermin approach

    E-print Network

    A. V. Latyshev; A. A. Yushkanov

    2012-10-11

    Formulas for transversal electric conductivity and dielectric permeability of quantum collisional plasma are deduced. The kinetic equation for a density matrix in relaxation approaching in momentum space is used. It is shown, that when Planck's constant tends to zero, these deduced formulas pass in classical expressions and when frequency of electron collision tends to zero (i.e. plasma passes in collisionless plasma), the deduced formulas pass in deduced earlier by Lindhard. It is shown also, that when the wave number tends to zero, quantum conductivity passes in the classical one. Graphic comparison of the deduced conductivity with Lindhard's conductivity and with classical conductivity is carry out.

  18. Detection of temperature distribution via recovering electrical conductivity in MREIT.

    PubMed

    Oh, Tong In; Kim, Hyung Joong; Jeong, Woo Chul; Chauhan, Munish; Kwon, Oh In; Woo, Eung Je

    2013-04-21

    In radiofrequency (RF) ablation or hyperthermia, internal temperature measurements and tissue property imaging are important to control their outputs and assess the treatment effect. Recently, magnetic resonance electrical impedance tomography (MREIT), as a non-invasive imaging method of internal conductivity distribution using an MR scanner, has been developed. Its reconstruction algorithm uses measured magnetic flux density induced by injected currents. The MREIT technique has the potential to visualize electrical conductivity of tissue with high spatial resolution and measure relative conductivity variation according to the internal temperature change based on the fact that the electrical conductivity of biological tissues is sensitive to the internal temperature distribution. In this paper, we propose a method to provide a non-invasive alternative to monitor the internal temperature distribution by recovering the electrical conductivity distribution using the MREIT technique. To validate the proposed method, we design a phantom with saline solution and a thin transparency film in a form of a hollow cylinder with holes to create anomalies with different electrical and thermal conductivities controlled by morphological structure. We first prove the temperature maps with respect to spatial and time resolution by solving the thermal conductivity partial differential equation with the real phantom experimental environment. The measured magnetic flux density and the reconstructed conductivity distributions using the phantom experiments were compared to the simulated temperature distribution. The relative temperature variation of two testing objects with respect to the background saline was determined by the relative conductivity contrast ratio (rCCR,%). The relation between the temperature and conductivity measurements using MREIT was approximately linear with better accuracy than 0.22 °C. PMID:23552880

  19. Detection of temperature distribution via recovering electrical conductivity in MREIT

    NASA Astrophysics Data System (ADS)

    In Oh, Tong; Kim, Hyung Joong; Jeong, Woo Chul; Chauhan, Munish; In Kwon, Oh; Woo, Eung Je

    2013-04-01

    In radiofrequency (RF) ablation or hyperthermia, internal temperature measurements and tissue property imaging are important to control their outputs and assess the treatment effect. Recently, magnetic resonance electrical impedance tomography (MREIT), as a non-invasive imaging method of internal conductivity distribution using an MR scanner, has been developed. Its reconstruction algorithm uses measured magnetic flux density induced by injected currents. The MREIT technique has the potential to visualize electrical conductivity of tissue with high spatial resolution and measure relative conductivity variation according to the internal temperature change based on the fact that the electrical conductivity of biological tissues is sensitive to the internal temperature distribution. In this paper, we propose a method to provide a non-invasive alternative to monitor the internal temperature distribution by recovering the electrical conductivity distribution using the MREIT technique. To validate the proposed method, we design a phantom with saline solution and a thin transparency film in a form of a hollow cylinder with holes to create anomalies with different electrical and thermal conductivities controlled by morphological structure. We first prove the temperature maps with respect to spatial and time resolution by solving the thermal conductivity partial differential equation with the real phantom experimental environment. The measured magnetic flux density and the reconstructed conductivity distributions using the phantom experiments were compared to the simulated temperature distribution. The relative temperature variation of two testing objects with respect to the background saline was determined by the relative conductivity contrast ratio (rCCR,%). The relation between the temperature and conductivity measurements using MREIT was approximately linear with better accuracy than 0.22 °C.

  20. 7. VIEW OF THE HOT BED FOR THE CONTINUOUS ELECTRIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW OF THE HOT BED FOR THE CONTINUOUS ELECTRIC FURNACE HEAT TREATING LINE AT THE HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  1. 8. QUENCHING MECHANISM FOR THE CONTINUOUS ELECTRIC FURNACE HEAT TREATING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. QUENCHING MECHANISM FOR THE CONTINUOUS ELECTRIC FURNACE HEAT TREATING LINE AT THE HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  2. Studies with sample conductivity, insertion rates, and particle deflection in a continuous flow electrophoresis system

    NASA Technical Reports Server (NTRS)

    Williams, G., Jr.

    1982-01-01

    The continuous flow electrophoresis system makes electrophoresis possible in a free-flowing film of aqueous electrolyte medium. The sample continuously enters the electrolyte at the top of the chamber and is subjected to the action of a lateral dc field. This divides the sample into fractions since each component has a distinctive electrophoretic mobility. Tests were made using monodisperse polystyrene latex microspheres to determine optimum sample conductivity, insertion rates and optimum electric field applications as baseline data for future STS flight experiments. Optimum sample flow rates for the selected samples were determined to be approximately 26 micro-liters/min. Experiments with samples in deionized water yielded best results and voltages in the 20 V/cm to 30 V/cm range were optimum. Deflections of formaldehyde fixed turkey and bovine erythrocytes were determined using the continuous flow electrophoresis system. The effects of particle interactions on sample resolution and migration in the chamber was also evaluated.

  3. Thermal conductivity and electrical resistivity of porous material

    NASA Technical Reports Server (NTRS)

    Koh, J. C. Y.; Fortini, A.

    1971-01-01

    Thermal conductivity and electrical resistivity of porous materials, including 304L stainless steel Rigimesh, 304L stainless steel sintered spherical powders, and OFHC sintered spherical powders at different porosities and temperatures are reported and correlated. It was found that the thermal conductivity and electrical resistivity can be related to the solid material properties and the porosity of the porous matrix regardless of the matrix structure. It was also found that the Wiedermann-Franz-Lorenz relationship is valid for the porous materials under consideration. For high conductivity materials, the Lorenz constant and the lattice component of conductivity depend on the material and are independent of the porosity. For low conductivity, the lattice component depends on the porosity as well.

  4. Rotating electrical joints with continuous metallic connections

    NASA Astrophysics Data System (ADS)

    Mäusli, P.-A.; Feusier, G.; Gass, V.

    2003-09-01

    The need for very low noise, low RF loss dynamic rotating electrical connections exist, in particular for pointing mechanisms requiring very high stability. Four basic designs are presented: 1. the cable-wrap (clock-spring shaped flat cable. 2. The vertical goose-neck (flat cable squeezed between two rotating cylinders). 3. The horizontal goose-neck (flat cable squeezed between two parallel disks). 4. The twist cable (twisted cable bundle in a cylindrical housing). The choice of the appropriate design is highly dependent on the following parameters: available space and shape, torque, angular range, current, signal type to be transferred. A discussion of the design selection parameters, and typical achievable performances will be presented. The cable wrap design is favourable when the Housing diameter (outer diameter O.D.) to Drum diameter (inner diameter I.D.) ratio is large. When this ratio tends to unity, the gooseneck design is preferable and is essentially limited by the bending radius of the cable sheet that is directly related to the life of the mechanism.

  5. Strong and Electrically Conductive Graphene Based Composite Fibers and Laminates

    DOE PAGESBeta

    Vlassiouk, Ivan V.; Polyzos, Georgios; Cooper, Ryan C.; Ivanov, Ilia N.; Keum, Jong Kahk; Paulauskas, Felix L.; Datskos, Panos G.; Smirnov, Sergei

    2015-04-28

    Graphene is an ideal candidate for lightweight, high-strength composite materials given its superior mechanical properties (specific strength of 130 GPa and stiffness of 1 TPa). To date, easily scalable graphene-like materials in a form of separated flakes (exfoliated graphene, graphene oxide, and reduced graphene oxide) have been investigated as candidates for large-scale applications such as material reinforcement. These graphene-like materials do not fully exhibit all the capabilities of graphene in composite materials. In this study, we show that macro (2 inch × 2 inch) graphene laminates and fibers can be produced using large continuous sheets of single-layer graphene grown bymore »chemical vapor deposition. The resulting composite structures have potential to outperform the current state-of-the-art composite materials in both mechanical properties and electrical conductivities (>8 S/cm with only 0.13% volumetric graphene loading and 5 × 103 S/cm for pure graphene fibers) with estimated graphene contributions of >10 GPa in strength and 1 TPa in stiffness.« less

  6. Fabrication of highly conductive carbon nanotube fibers for electrical application

    NASA Astrophysics Data System (ADS)

    Guo, Fengmei; Li, Can; Wei, Jinquan; Xu, Ruiqiao; Zhang, Zelin; Cui, Xian; Wang, Kunlin; Wu, Dehai

    2015-09-01

    Carbon nanotubes (CNTs) have great potential for use as electrical wires because of their outstanding electrical and mechanical properties. Here, we fabricate lightweight CNT fibers with electrical conductivity as high as that of stainless steel from macroscopic CNT films by drawing them through diamond wire-drawing dies. The entangled CNT bundles are straightened by suffering tension, which improves the alignment of the fibers. The loose fibers are squeezed by the diamond wire-drawing dies, which reduces the intertube space and contact resistance. The CNT fibers prepared by drawing have an electrical conductivity as high as 1.6 × 106 s m-1. The fibers are very stable when kept in the air and under cyclic tensile test. A prototype of CNT motor is demonstrated by replacing the copper wires with the CNT fibers.

  7. Effect of Lubricants and Annealing Treatment on the Electrical Conductivity and Microstructure of Rolled Copper Foil

    NASA Astrophysics Data System (ADS)

    Xiong, Sang; Sun, Jianlin; Xu, Yang; Yan, Xundong

    2015-07-01

    X-ray diffraction and transmission electron microscopy have been used to study the microstructure of copper foil during rolling. Annealing was used to release work hardening of rolled copper foil (RCF), and electrical conductivity was determined by use of a PPMS-9 comprehensive physical property-measurement system. The microstructure and electrical conductivity of RCF are discussed. Our results showed that the relative intensity of the (220) diffraction peak increased continuously with decreasing sample thickness and that rolling induced preferred orientation. Many obvious crystallographic defects were present; these seriously affected electrical conductivity. The electrical conductivity of RCF decreases with increasing lattice distortion and micro defects which occur during deformation, especially when the surface adsorbs lubricant. However, annealing reduced lattice distortion and the scattering of conducting electrons at these defects, thus improving the electrical properties. For foil thickness in the range 25-180 ?m, annealing temperatures in the range 150-300°C, and annealing times in the range 2.5-3.0 h, the electrical conductivity of RCF increased with increasing thickness and annealing temperature, and decreased with increasing annealing time.

  8. Shear induced electrical behaviour of conductive polymer composites

    NASA Astrophysics Data System (ADS)

    Starý, Zden?k; Krückel, Johannes; Schubert, Dirk W.

    2013-04-01

    The time-dependent electrical resistance of polymethylmethacrylate containing carbon black was measured under oscillatory shear in the molten state. The electrical signal was oscillating exactly at the doubled frequency of the oscillatory shear deformation. Moreover, the experimental results gave a hint to the development of conductive structures in polymer melts under shear deformation. It was shown that the flow induced destruction of conductive paths dominates over the flow induced build-up in the beginning of the shear deformations. However, for longer times both competitive effects reach a dynamic equilibrium and only the thermally induced build-up of pathways influences the changes in the composite resistance during the shear. Furthermore, the oscillating electrical response depends clearly on the deformation amplitude applied. A simple physical model describing the behaviour of conductive pathways under shear deformation was derived and utilized for the description of the experimental data.

  9. Electrical and thermal conductivity of hybrid nanocomposites with giant strain

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  10. Electrically conductive bacterial nanowires produced by Shewanella oneidensis strain MR-1

    E-print Network

    Electrically conductive bacterial nanowires produced by Shewanella oneidensis strain MR-1 and other (received for review September 20, 2005) Shewanella oneidensis MR-1 produced electrically conductive pi- lus, fermentative bacterium Pelotomaculum thermopropionicum reveal that electrically conductive append- ages

  11. Corrosion-protective coatings from electrically conducting polymers

    NASA Technical Reports Server (NTRS)

    Thompson, Karen Gebert; Bryan, Coleman J.; Benicewicz, Brian C.; Wrobleski, Debra A.

    1991-01-01

    In a joint effort between NASA Kennedy and LANL, electrically conductive polymer coatings were developed as corrosion protective coatings for metal surfaces. At NASA Kennedy, the launch environment consist of marine, severe solar, and intermittent high acid and/or elevated temperature conditions. Electrically conductive polymer coatings were 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.

  12. Electrically conductive doped block copolymer of polyacetylene and polyisoprene

    DOEpatents

    Aldissi, Mahmoud (Los Alamos, NM)

    1985-01-01

    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.

  13. Instrumentation development for electrical conductivity imaging in polycrystalline diamond cutters

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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.

  14. Electrical conductivity measurements on silicate melts using the loop technique

    NASA Technical Reports Server (NTRS)

    Waff, H. S.

    1976-01-01

    A new method is described for measurement of the electrical conductivity of silicate melts under controlled oxygen partial pressure at temperatures to 1550 C. The melt samples are suspended as droplets on platinum-rhodium loops, minimizing iron loss from the melt due to alloying with platinum, and providing maximum surface exposure of the melt to the oxygen-buffering gas atmosphere. The latter provides extremely rapid equilibration of the melt with the imposed oxygen partial pressure. The loop technique involves a minimum of setup time and cost, provides reproducible results to within + or - 5% and is well suited to electrical conductivity studies on silicate melts containing redox cations.

  15. Electrically conducting porphyrin and porphyrin-fullerene electropolymers

    DOEpatents

    Gust, Jr., John Devens; Liddell, Paul Anthony; Gervaldo, Miguel Andres; Bridgewater, James Ward; Brennan, Bradley James; Moore, Thomas Andrew; Moore, Ana Lorenzelli

    2014-03-11

    Compounds with aryl ring(s) at porphyrin meso position(s) bearing an amino group in position 4 relative to the porphyrin macrocycle, and at least one unsubstituted 5 (hydrogen-bearing) meso position with the 10-, 15-, and/or 20-relationship to the aryl ring bearing the amino group, and metal complexes thereof, feature broad spectral absorption throughout the visible region. These compounds are electropolymerized to form electrically conducting porphyrin and porphyrin-fullerene polymers that are useful in photovoltaic applications. The structure of one such electrically conducting porphyrin polymer is shown below. ##STR00001##

  16. Electrically Joining Mixed Conducting Oxides for High Temperature Applications

    SciTech Connect

    Weil, K. Scott; Hardy, John S.

    2003-01-06

    Mixed conducting oxides such as lanthanum strontium cobalt ferrite are currently being investigated for potential use as electrochemically active electrodes and catalytic membranes in a number of high temperature devices, including oxygen generators and solid oxide fuel cells (SOFC). However to take full advantage of the unique properties of these materials, reliable joining techniques need to be developed. What complicates joining in these applications is the requirement that the ceramic-to-metal junction be electrically conductive, so that current can either be drawn from the mixed conducting oxide, in the case of SOFC applications, or be carried to the oxide to initate ionic conduction, as required for oxygen separation and electrocatalysis. This paper outlines a new technique that is being developed to electrically join an oxide conductor to a metal current collector for high temperature electrochemical application.

  17. Carbonatite melts and electrical conductivity in the asthenosphere.

    PubMed

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

    2008-11-28

    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

  18. Tuning Electrical Conductivity of Inorganic Minerals with Carbon Nanomaterials.

    PubMed

    Kovalchuk, Anton A; Tour, James M

    2015-12-01

    Conductive powders based on Barite or calcium carbonate with chemically converted graphene (CCG) were successfully synthesized by adsorption of graphene oxide (GO) or graphene oxide nanoribbons (GONRs) onto the mineral surfaces and subsequent chemical reduction with hydrazine. The efficient adsorption of GO or GONRs on the surface of Barite and calcium carbonate-based mineral particles results in graphene-wrapped hybrid materials that demonstrate a concentration dependent electrical conductivity that increases with the GO or GONR loading. PMID:26544547

  19. Using nano hexagonal boron nitride particles and nano cubic silicon carbide particles to improve the thermal conductivity of electrically conductive adhesives

    NASA Astrophysics Data System (ADS)

    Cui, Hui-wang; Li, Dong-sheng; Fan, Qiong

    2013-01-01

    To satisfy the high electrical and thermal conductivity required for the continuous development of electronic products, nano hexagonal boron nitride (BN) particles and nano cubic silicon carbide (SiC) particles were added into electrically conductive adhesives (ECAs) to improve the thermal conductivity. BN and SiC had little negative effect on the electrical conductivity, but improved the thermal conductivity significantly. When their content was 1.5 wt. %, the thermal conductivity at 100°C, 150°C and 200°C was increased by 71% (100°C), 78% (150°C) and 70% (200°C), and 114% (100°C), 110% (150°C) and 98% (200°C) respectively for BN and SiC comparing with those of the ECAs with no thermal conductive fillers. This method is simple, easy to do, and can be used practically in electronic packaging.

  20. Osteoblast function on electrically conductive electrospun PLA/MWCNTs nanofibers.

    PubMed

    Shao, Shijun; Zhou, Shaobing; Li, Long; Li, Jinrong; Luo, Chao; Wang, Jianxin; Li, Xiaohong; Weng, Jie

    2011-04-01

    The electrospinning process was utilized successfully to fabricate the random oriented and aligned electrically conductive nanofibers of biodegradable poly-DL-lactide (PLA) in which multiwalled carbon nanotubes (MWCNTs) were embedded. The topographical features of the composite nanofibers were characterized by SEM. The dispersion and alignment of MWCNTs in nanofiber matrix were observed by TEM. The in vitro degradation was characterized in terms of the morphological change, the mass loss and the reduction of polymer molecular weight as well as the decrease of pH value of degradation media. In particular, these conductive nanofiber meshes offered a unique system to study the synergistic effect of topographic cues and electrical stimulation on osteoblasts outgrowth as a way of exploring their potential application in bone tissue engineering. The results of obsteoblasts assay unstimulated showed that the aligned nanofibers as topographic cues could enhance the extension and direct the outgrowth of obsteoblasts better than random fibers. In the presence of direct current (DC) of 100 ?A, the obsteoblasts on all samples grew along the electrical current direction. The cellular elongation and proliferation were mainly dependent on the electrical stimulation whereas the topographical features played a minor role in them. Therefore, electrical stimulation with an appropriate DC value imparted on conductive substrate had great potential in application of bone tissue engineering. PMID:21292320

  1. Soil water sensor response to bulk electrical conductivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil water monitoring using electromagnetic (EM) sensors can facilitate observations of water content at high temporal and spatial resolutions. These sensors measure soil dielectric permittivity (Ka) which is largely a function of volumetric water content. However, bulk electrical conductivity BEC c...

  2. Electrically conductive polycrystalline diamond and particulate metal based electrodes

    DOEpatents

    Swain, Greg M.; Wang, Jian

    2005-04-26

    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 current densities and potentials. The electrode is particularly useful for generating hydrogen, and for reducing oxygen and oxidizing methanol in reactions which are of importance in fuel cells.

  3. UNCERTAINTY EFFECTS ON ELECTRICAL CONDUCTIVITY AND PERMITTIVITY SPECTRA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil permittivity and electrical conductivity values are usually reported without error bars, which limits comparisons among different studies using different equipment. Uncertainty in measured permittivity spectra could be due to the measurement system (hardware) or sample-to-sample variation. Ther...

  4. 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...

  5. www.VadoseZoneJournal.org Electrical Conductivity Imaging

    E-print Network

    Hubbard, Susan

    in an Arctic Ecosystem, through Advanced Inversion of Electromagnetic Induction Data Characterizing the spatial electromagnetic induction (EMI) data with portable tools (e.g., EM38, GEM2, or DUALEM) over large regions, EMI conductivity; EMI, electromagnetic induction; ERT, electrical resistance tomography; MCMC, Markov chain Monte

  6. SOIL ELECTRICAL CONDUCTIVITY AS A MANAGEMENT TOOL IN PRECISION FORESTRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Apparent soil electrical conductivity (ECa) is a useful measurement and indicator of relative productivity of agronomic crops on some soil types. In non-saline soils, spatial variation in soil ECa is strongly related to texture, topsoil depth and profile variations; factors which spatially correlate...

  7. Composite yarns of multiwalled carbon nanotubes with metallic electrical conductivity.

    PubMed

    Randeniya, Lakshman K; Bendavid, Avi; Martin, Philip J; Tran, Canh-Dung

    2010-08-16

    Unique macrostructures known as spun carbon-nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room-temperature conductivities of about 5 x 10(2) S cm(-1). Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal-CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self-fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu-CNT and Au-CNT composite yarns prepared by this method have metal-like electrical conductivities (2-3 x 10(5) S cm(-1)) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30-50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications. PMID:20665629

  8. Time resolved strain dependent morphological study of electrically conducting nanocomposites

    NASA Astrophysics Data System (ADS)

    Khan, Imran; Mitchell, Geoffrey; Mateus, Artur; Kamma-Lorger, Christina S.

    2015-10-01

    An efficient and reliable method is introduced to understand the network behaviour of nano-fillers in a polymeric matrix under uniaxial strain coupled with small angle x-ray scattering measurements. The nanoparticles (carbon nanotubes) are conductive and the particles form a percolating network that becomes apparent source of electrical conduction and consequently the samples behave as a bulk conductor. Polyurethane based nanocomposites containing 2% w/w multiwall carbon nanotubes are studied. The electrical conductivity of the nanocomposite was (3.28×10-5s/m).The sample was able to be extended to an extension ratio of 1.7 before fracture. A slight variation in the electrical conductivity is observed under uniaxial strain which we attribute to the disturbance of conductive pathways. Further, this work is coupled with in- situ time resolved small angle x-ray scattering measurements using a synchrotron beam line to enable its measurements to be made during the deformation cycle. We use a multiscale structure to model the small angle x-ray data. The results of the analysis are interpreted as the presence of aggregates which would also go some way towards understanding why there is no alignment of the carbon nanotubes.

  9. Electrical conductivity and dielectric property of fly ash geopolymer pastes

    NASA Astrophysics Data System (ADS)

    Hanjitsuwan, Sakonwan; Chindaprasirt, Prinya; Pimraksa, Kedsarin

    2011-02-01

    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.

  10. Electric field in the vicinity of long thin conducting rods

    NASA Astrophysics Data System (ADS)

    Rezinkina, M. M.; Rezinkin, O. L.; Svetlichnaya, E. E.

    2015-09-01

    We report on the results of numerical and analytical calculations of distributions of potentials and electric fields in the vicinity of thin conducting rods that model the leader channel of lightning and lightning rods. We consider rods represented in the form of a uniformly charged filament, a conducting ellipsoid with a free charge on its surface, as well an ellipsoid or a cylinder in a uniform external electric field. The effect of parameters of conducting rods modeling the leader channel of lightning and lightning rods, as well as the region containing a space charge around the tip of the leader channel, on the distribution of potentials and field strengths are analyzed. The conditions for the propagation of the counter leader from the lightning rod are specified.

  11. Contactless electrical conductivity measurement of electromagnetically levitated metallic melts

    SciTech Connect

    Richardsen, T.; Lohoefer, G.

    1999-07-01

    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.

  12. Rearrangement of 1D Conducting Nanomaterials towards Highly Electrically Conducting Nanocomposite Fibres for Electronic Textiles

    PubMed Central

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-01-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 105?S m?1) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors. PMID:25792333

  13. Rearrangement of 1D conducting nanomaterials towards highly electrically conducting nanocomposite fibres for electronic textiles.

    PubMed

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-01-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 10(5) S m(-1)) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors. PMID:25792333

  14. Rearrangement of 1D Conducting Nanomaterials towards Highly Electrically Conducting Nanocomposite Fibres for Electronic Textiles

    NASA Astrophysics Data System (ADS)

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-03-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 105 S m-1) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors.

  15. Synthesis of Conductive Nanofillers/Nanofibers and Electrical Properties of their Conductive Polymer Composites

    NASA Astrophysics Data System (ADS)

    Sarvi, Ali

    Thanks to their corrosion resistance, light weight, low cost, and ease of processing, electrically conducting polymer composites (CPCs) have received significant attention for the replacement of metals and inorganic materials for sensors, actuators, supercapacitors, and electromagnetic interference (EMI) shields. In this PhD thesis, high aspect ratio conductive nanofillers namely copper nanowires (CuNWs) and multiwall carbon nanotubes (MWCNTs) were coated with polyaniline (PANi) using solution mixing and in-situ polymerization method, respectively. Transmission electron microscopy (TEM) showed a smooth polyaniline nano-coating between 5--18 nm in thickness on the nanofillers' surface. The coating thickness and; consequently, electrical conductivity was controlled and tuned by polyaniline/aniline concentration in solution. Composites with tunable conductivity may be used as chemisensors, electronic pressure sensors and switches. Coated nanofillers demonstrated better dispersion in polystyrene (PS) and provided lower electrical percolation threshold. Dispersion of nanofillers in PS was investigated using rheological measurements and confirmed with electron micrographs and nano-scale images of CPCs. Polyaniline (PANi), when used as a coating layer, was able to attenuate electromagnetic (EM) waves via absorption and store electrical charges though pseudocapacitance mechanism. The dielectric measurements of MWCNT-PANi/PS composites showed one order of magnitude increase in real electrical permittivity compared to that of MWCNT/PS composites making them suitable for charge storage purposes. Incorporation of PANi also brought a new insight into conductive network formation mechanism in electrospun mats where the orientation of conductive high aspect ratio nanofillers is a major problem. Conductive nanofibers of poly(vinylidene fluoride) (PVDF) filled with coated multiwall carbon nanotubes (MWCNTs) were fabricated using electrospinning. These highly oriented PVDF nanofibers exhibited high beta (beta) crystal content and enhanced piezoelectricity. Moreover, multilayer electrospun nanofibers, in which MWCNTs were located at the shell layer, were fabricated for further decrease in electrical percolation threshold. In addition the PANi coated nanofillers, immiscible polymer blends (poly(methyl methacrylate) (PMMA) and styrene-acrylonitrile copolymer (SAN) blends) were employed to deliver lower percolation threshold via double percolation phenomenon. Conductivity measurements revealed a significant decrease in electrical percolation threshold (0.4 wt%) for PMMA70/SAN30 blends compared with MWCNT-filled SAN and PMMA (ca 0.8 wt%).

  16. Estimates of olivine-basaltic melt electrical conductivity using a digital rock physics approach

    NASA Astrophysics Data System (ADS)

    Miller, Kevin J.; Montési, Laurent G. J.; Zhu, Wen-lu

    2015-12-01

    Estimates of melt content beneath fast-spreading mid-ocean ridges inferred from magnetotelluric tomography (MT) vary between 0.01 and 0.10. Much of this variation may stem from a lack of understanding of how the grain-scale melt geometry influences the bulk electrical conductivity of a partially molten rock, especially at low melt fraction. We compute bulk electrical conductivity of olivine-basalt aggregates over 0.02 to 0.20 melt fraction by simulating electric current in experimentally obtained partially molten geometries. Olivine-basalt aggregates were synthesized by hot-pressing San Carlos olivine and high-alumina basalt in a solid-medium piston-cylinder apparatus. Run conditions for experimental charges were 1.5 GPa and 1350 °C. Upon completion, charges were quenched and cored. Samples were imaged using synchrotron X-ray micro-computed tomography (?-CT). The resulting high-resolution, 3-dimensional (3-D) image of the melt distribution constitutes a digital rock sample, on which numerical simulations were conducted to estimate material properties. To compute bulk electrical conductivity, we simulated a direct current measurement by solving the current continuity equation, assuming electrical conductivities for olivine and melt. An application of Ohm's Law yields the bulk electrical conductivity of the partially molten region. The bulk electrical conductivity values for nominally dry materials follow a power-law relationship ?bulk = C?melt?m with fit parameters m = 1.3 ± 0.3 and C = 0.66 ± 0.06. Laminar fluid flow simulations were conducted on the same partially molten geometries to obtain permeability, and the respective pathways for electrical current and fluid flow over the same melt geometry were compared. Our results indicate that the pathways for flow fluid are different from those for electric current. Electrical tortuosity is lower than fluid flow tortuosity. The simulation results are compared to existing experimental data, and the potential influence of volatiles and melt films on electrical conductivity of partially molten rocks is discussed.

  17. Facile synthesis of degradable and electrically conductive polysaccharide hydrogels.

    PubMed

    Guo, Baolin; Finne-Wistrand, Anna; Albertsson, Ann-Christine

    2011-07-11

    Degradable and electrically conductive polysaccharide hydrogels (DECPHs) have been synthesized by functionalizing polysaccharide with conductive aniline oligomers. DECPHs based on chitosan (CS), aniline tetramer (AT), and glutaraldehyde were obtained by a facile one-pot reaction by using the amine group of CS and AT under mild conditions, which avoids the multistep reactions and tedious purification involved in the synthesis of degradable conductive hydrogels in our previous work. Interestingly, these one-pot hydrogels possess good film-forming properties, electrical conductivity, and a pH-sensitive swelling behavior. The chemical structure and morphology before and after swelling of the hydrogels were verified by FT-IR, NMR, and SEM. The conductivity of the hydrogels was tuned by adjusting the content of AT. The swelling ratio of the hydrogels was altered by the content of tetraaniline and cross-linker. The hydrogels underwent slow degradation in a buffer solution. The hydrogels obtained by this facile approach provide new possibilities in biomedical applications, for example, biodegradable conductive hydrogels, films, and scaffolds for cardiovascular tissue engineering and controlled drug delivery. PMID:21574634

  18. Optimization and Testing of Electrically Conductive Spacecraft Coatings

    NASA Technical Reports Server (NTRS)

    Mell, Richard J.

    2001-01-01

    This is the final report discussing work done for the Space Environmental Effects (SEE) program in the Materials and Processes Laboratory, on electrically conductive thermal control coatings. These thermal control coatings are being developed to have several orders of magnitude lower electrical resistivity than most available thermal control coatings. Extensive research has taken place over the last few years to develop a variety of spacecraft coatings with the unique property of being able to conduct surface charge to a substrate or grounding system. The ability to conduct surface charge to a safe point, while maintaining optical properties and performance, is highly advantageous in maintaining operational space based systems. Without this mechanism the surface of a spacecraft can accumulate charge to the point that a catastrophic electrical breakdown can occur, resulting in damage to or failure of the spacecraft. Ultimately, use of this type of coating will help mitigate many of the concerns that NASA and the space industry still have for their space based systems. The unique coatings studied here fall into two specific categories: 1) broadband absorber and 2) selective absorber. These coatings have controllable solar absorptance and electrical surface resistivity values over the designated ranges. These coatings were developed under an SBIR program which focused on the development of such constituents and coatings. This project focused on simulated space environmental effects testing with the intent of using this data to help optimize the stability and initial properties of these coatings.

  19. Relative contribution of ionospheric conductivity and electric field to the auroral electrojets

    SciTech Connect

    Kamide, Y.; Vickrey, J.F.

    1983-10-01

    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.

  20. Electrical conductivity of olivine: New experimental results and a unified model for hydrogen-assisted conduction

    NASA Astrophysics Data System (ADS)

    Karato, S.; Dai, L.

    2013-12-01

    Although extensive experimental studies have been carried out on the hydrogen-assisted electrical conductivity in olivine, a few important issues remain unclear. We have conducted new experiments (i) on the pressure effects, (ii) on the influence of Fe content, and (iii) on the influence of oxygen fugacity on hydrogen-assisted conductivity to clarify these issues. The pressure effect is important in resolving the difference between Wang et al. (2006) and Yoshino et al. (2009) and also in evaluating the conductivity jump at the 410-km discontinuity. Our new results show only a small effect of pressure indicating that (i) the difference between Wang et al. (2006) and Yoshino et al. (2009) is not due to the pressure effect, and that (ii) there must be a large drop in conductivity at 410-km boundary if the water content in the upper mantle is the same as that of the transition zone. We also conducted a series of experiments to determine the influence of Fe on hydrogen-assisted conductivity. Both Fe and hydrogen enhance conductivity, but their combined effect was not characterized. We found that Fe effect and hydrogen effect are connected: for given hydrogen content, conductivity is higher for a sample with higher Fe content. This implies that the hydrogen mobility is enhanced by Fe. The results have potential applications for Fe-rich planets such as Mars. We are also conducting a series of experiments to see the influence of oxygen fugacity on hydrogen-assisted conductivity. A similar study was made for wadsleyite showing the negative dependence of conductivity on oxygen fugacity showing a simple model of hydrogen-assisted conductivity (i.e., all hydrogen atoms contribute equally to conductivity) does not work. Our new results will provide strong constraints on the mechanism of hydrogen-assisted conduction in olivine. A hybrid model explains a broad range of observations including the discrepancies between diffusion data and electrical conductivity, and predicts that hydrogen-assisted conductivity will be highly anisotropic at high temperatures.

  1. Thermal and Electrical Conductivity Probe for Phoenix Mars Lander

    NASA Technical Reports Server (NTRS)

    2007-01-01

    NASA's Phoenix Mars Lander will assess how heat and electricity move through Martian soil from one spike or needle to another of a four-spike electronic fork that will be pushed into the soil at different stages of digging by the lander's Robotic Arm.

    The four-spike tool, called the thermal and electrical conductivity probe, is in the middle-right of this photo, mounted near the end of the arm near the lander's scoop (upper left).

    In one type of experiment with this tool, a pulse of heat will be put into one spike, and the rate at which the temperature rises on the nearby spike will be recorded, along with the rate at which the heated spike cools. A little bit of ice can make a big difference in how well soil conducts heat. Similarly, soil's electrical conductivity -- also tested with this tool -- is a sensitive

    indicator of moisture in the soil. This device adapts technology used in soil-moisture gauges for irrigation-control systems. The conductivity probe has an additional role besides soil analysis. It will serve as a hunidity sensor when held in the air.

  2. The Thermal Electrical Conductivity Probe (TECP) for Phoenix

    NASA Technical Reports Server (NTRS)

    Zent, Aaron P.; Hecht, Michael H.; Cobos, Doug R.; Campbell, Gaylon S.; Campbell, Colin S.; Cardell, Greg; Foote, Marc C.; Wood, Stephen E.; Mehta, Manish

    2009-01-01

    The Thermal and Electrical Conductivity Probe (TECP) is a component of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) payload on the Phoenix Lander. TECP will measure the temperature, thermal conductivity and volumetric heat capacity of the regolith. It will also detect and quantify the population of mobile H2O molecules in the regolith, if any, throughout the polar summer, by measuring the electrical conductivity of the regolith, as well as the dielectric permittivity. In the vapor phase, TECP is capable of measuring the atmospheric H2O vapor abundance, as well as augment the wind velocity measurements from the meteorology instrumentation. TECP is mounted near the end of the 2.3 m Robotic Arm, and can be placed either in the regolith material or held aloft in the atmosphere. This paper describes the development and calibration of the TECP. In addition, substantial characterization of the instrument has been conducted to identify behavioral characteristics that might affect landed surface operations. The greatest potential issue identified in characterization tests is the extraordinary sensitivity of the TECP to placement. Small gaps alter the contact between the TECP and regolith, complicating data interpretation. Testing with the Phoenix Robotic Arm identified mitigation techniques that will be implemented during flight. A flight model of the instrument was also field tested in the Antarctic Dry Valleys during the 2007-2008 International Polar year. 2

  3. Electrical conductivity of tissue at frequencies below 1 MHz

    NASA Astrophysics Data System (ADS)

    Gabriel, C.; Peyman, A.; Grant, E. H.

    2009-08-01

    A two-pronged approach, review and measurement, has been adopted to characterize the conductivity of tissues at frequencies below 1 MHz. The review covers data published in the last decade and earlier data not included in recent reviews. The measurements were carried out on pig tissue, in vivo, and pig body fluids in vitro. Conductivity data have been obtained for skeletal and myocardial muscle, liver, skull, fat, lung and body fluids (blood, bile, CSF and urine). A critical analysis of the data highlights their usefulness and limitations and enables suggestions to be made for measuring the electrical properties of tissues.

  4. Single-photon heat conduction in electrical circuits

    E-print Network

    P. J. Jones; J. A. M. Huhtamäki; K. Y. Tan; M. Möttönen

    2011-07-14

    We study photonic heat conduction between two resistors coupled weakly to a single superconducting microwave cavity. At low enough temperature, the dominating part of the heat exchanged between the resistors is transmitted by single-photon excitations of the fundamental mode of the cavity. This manifestation of single-photon heat conduction should be experimentally observable with the current state of the art. Our scheme can possibly be utilized in remote interference-free temperature control of electric components and environment engineering for superconducting qubits coupled to cavities.

  5. Electrical contact resistance theory for conductive rough surfaces

    NASA Astrophysics Data System (ADS)

    Kogut, L.; Komvopoulos, K.

    2003-09-01

    A general electrical contact resistance (ECR) theory for conductive rough surfaces was derived from first principles. The analysis is based on fractal geometry for the surface topography description, elastic-plastic deformation of contacting asperities, and size-dependent constriction resistance of microcontacts. Relations for the ECR in terms of contact load and apparent contact area are obtained for isotropic, homogeneous, conductive surfaces with known material properties and surface topography. Useful design guidelines for electrical contacts are extracted from the numerical results. A general relation between the dimensionless real contact area and the dimensionless ECR is introduced for lightly loaded contacts that depends only on the electron mean free path. Approaches for determining the surface roughness, material properties, and real contact area are discussed in the context of relatively simple ECR measurements.

  6. Electrical conductivity of two-phase composite material

    SciTech Connect

    Kovacik, J.

    1998-06-12

    It is a long standing problem to predict the effective electrical conductivity of binary mixtures or two-phase composites. The early history of this problem is often connected with the names of Clausius, Mossotti, Lorenz, and Lorentz. Currently, the general effective media (GEM) equation, proposed by McLachlan, seems to explain different results of experimental studies over an entire composition range. The GEM equation consists of electrical conductivity of constituent phases, their volume fractions and two free parameters. As has been pointed out by Boccaccini the free parameters of the GEM equation do not have yet a clear correlation with the real features of the microstructure. In this paper the author discusses such correlation using connections among the GEM equation, percolation theory and effective medium theory.

  7. Nonideal ultrathin mantle cloak for electrically large conducting cylinders.

    PubMed

    Liu, Shuo; Zhang, Hao Chi; Xu, He-Xiu; Cui, Tie Jun

    2014-09-01

    Based on the concept of the scattering cancellation technique, we propose a nonideal ultrathin mantle cloak that can efficiently suppress the total scattering cross sections of an electrically large conducting cylinder (over one free-space wavelength). The cloaking mechanism is investigated in depth based on the Mie scattering theory and is simultaneously interpreted from the perspective of far-field bistatic scattering and near-field distributions. We remark that, unlike the perfect transformation-optics-based cloak, this nonideal cloaking technique is mainly designed to minimize simultaneously several scattering multipoles of a relatively large geometry around considerably broad bandwidth. Numerical simulations and experimental results show that the antiscattering ability of the metasurface gives rise to excellent total scattering reduction of the electrically large cylinder and remarkable electric-field restoration around the cloak. The outstanding cloaking performance together with the good features of and ultralow profile, flexibility, and easy fabrication predict promising applications in the microwave frequencies. PMID:25401449

  8. Electrical studies on silver based fast ion conducting glassy materials

    SciTech Connect

    Rao, B. Appa Kumar, E. Ramesh Kumari, K. Rajani Bhikshamaiah, G.

    2014-04-24

    Among all the available fast ion conductors, silver based glasses exhibit high conductivity. Further, glasses containing silver iodide enhances fast ion conducting behavior at room temperature. Glasses of various compositions of silver based fast ion conductors in the AgI?Ag{sub 2}O?[(1?x)B{sub 2}O{sub 3}?xTeO{sub 2}] (x=0 to1 mol% in steps of 0.2) glassy system have been prepared by melt quenching method. The glassy nature of the compounds has been confirmed by X-ray diffraction. The electrical conductivity (AC) measurements have been carried out in the frequency range of 1 KHz–3MHz by Impedance Analyzer in the temperature range 303–423K. The DC conductivity measurements were also carried out in the temperature range 300–523K. From both AC and DC conductivity studies, it is found that the conductivity increases and activation energy decreases with increasing the concentration of TeO{sub 2} as well as with temperature. The conductivity of the present glass system is found to be of the order of 10{sup ?2} S/cm at room temperature. The ionic transport number of these glasses is found to be 0.999 indicating that these glasses can be used as electrolyte in batteries.

  9. Electrically conductive chitosan/carbon scaffolds for cardiac tissue engineering.

    PubMed

    Martins, Ana M; Eng, George; Caridade, Sofia G; Mano, João F; Reis, Rui L; Vunjak-Novakovic, Gordana

    2014-02-10

    In this work, carbon nanofibers were used as doping material to develop a highly conductive chitosan-based composite. Scaffolds based on chitosan only and chitosan/carbon composites were prepared by precipitation. Carbon nanofibers were homogeneously dispersed throughout the chitosan matrix, and the composite scaffold was highly porous with fully interconnected pores. Chitosan/carbon scaffolds had an elastic modulus of 28.1 ± 3.3 KPa, similar to that measured for rat myocardium, and excellent electrical properties, with a conductivity of 0.25 ± 0.09 S/m. The scaffolds were seeded with neonatal rat heart cells and cultured for up to 14 days, without electrical stimulation. After 14 days of culture, the scaffold pores throughout the construct volume were filled with cells. The metabolic activity of cells in chitosan/carbon constructs was significantly higher as compared to cells in chitosan scaffolds. The incorporation of carbon nanofibers also led to increased expression of cardiac-specific genes involved in muscle contraction and electrical coupling. This study demonstrates that the incorporation of carbon nanofibers into porous chitosan scaffolds improved the properties of cardiac tissue constructs, presumably through enhanced transmission of electrical signals between the cells. PMID:24417502

  10. Effect of twist and porosity on the electrical conductivity of carbon nanofiber yarns.

    PubMed

    Chawla, S; Naraghi, M; Davoudi, A

    2013-06-28

    This study focuses on the effect of twist and porosity on the electrical conductivity of carbon nanofiber (CNF) yarns. The process of fabrication of CNF yarns included the synthesis of aligned ribbons of polyacrylonitrile (PAN) nanofibers via electrospinning. The PAN ribbons were twisted into yarns with twist levels ranging from zero twist to high twists of 1300 turn per meter (tpm). The twist imposed on the ribbons substantially improved the interactions between nanofibers and reduced the porosity. The PAN yarns were subsequently stabilized in air, and then carbonized in nitrogen at 1100 °C for 1 h. Compressive stresses developed between the PAN nanofibers as a result of twist promoted interfusion between neighboring nanofibers, which was accelerated by heating the yarns during stabilization to temperatures above the glass transition of PAN. The electrical conductivity of the yarns was measured with a four point probe measurement technique. Although increasing the twist promotes electrical conductivity between nanofibers by forming junctions between them, our results indicate that the electrical conductivity does not continuously increase with increasing twist, but reaches a threshold value after which it starts to decrease. The causes for this behavior were studied through experimental techniques and further explored using a yarn-equivalent electrical circuit model. PMID:23727878

  11. Effect of twist and porosity on the electrical conductivity of carbon nanofiber yarns

    NASA Astrophysics Data System (ADS)

    Chawla, S.; Naraghi, M.; Davoudi, A.

    2013-06-01

    This study focuses on the effect of twist and porosity on the electrical conductivity of carbon nanofiber (CNF) yarns. The process of fabrication of CNF yarns included the synthesis of aligned ribbons of polyacrylonitrile (PAN) nanofibers via electrospinning. The PAN ribbons were twisted into yarns with twist levels ranging from zero twist to high twists of 1300 turn per meter (tpm). The twist imposed on the ribbons substantially improved the interactions between nanofibers and reduced the porosity. The PAN yarns were subsequently stabilized in air, and then carbonized in nitrogen at 1100?° C for 1 h. Compressive stresses developed between the PAN nanofibers as a result of twist promoted interfusion between neighboring nanofibers, which was accelerated by heating the yarns during stabilization to temperatures above the glass transition of PAN. The electrical conductivity of the yarns was measured with a four point probe measurement technique. Although increasing the twist promotes electrical conductivity between nanofibers by forming junctions between them, our results indicate that the electrical conductivity does not continuously increase with increasing twist, but reaches a threshold value after which it starts to decrease. The causes for this behavior were studied through experimental techniques and further explored using a yarn-equivalent electrical circuit model.

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

    DOEpatents

    Tsang, K.L.; Chen, Y.

    1984-02-09

    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.

  13. Electrical conductivity of continental lithospheric mantle from integrated geophysical and petrological modeling

    E-print Network

    Jones, Alan G.

    Electrical conductivity of continental lithospheric mantle from integrated geophysical; published 11 October 2011. [1] The electrical conductivity of mantle minerals is highly sensitive review stateoftheart conductivity models based on laboratory studies for the most relevant upper mantle

  14. On the electrical conductivity of plasmas and metals

    E-print Network

    Crowley, Basil

    2015-01-01

    Methods for modelling the electrical conductivity of dense plasmas and liquid metals, based upon the well-known Ziman formula, are reviewed from a general perspective, and some earlier inconsistencies relating to its application to finite temperature systems are resolved. A general formula for the conductivity of a Lorentzian two-component plasma in thermal equilibrium is derived from the Lenard-Balescu collision integral in which both energy and momentum exchange between ions and electrons are accounted for. This formula is used as a basis for some generalizations of the Ziman formula, which apply to plasmas of arbitrary degeneracy over a much wider range of conditions. These formulae implicitly include the collective motions of the ions, but neglect the collective motions of the electrons. Detailed consideration of the latter shows that they generally have a small effect on the conductivity. Conditions for the validity of the Ziman formula are derived. The extension of the general theory to arbitrarily low ...

  15. High temperature electrically conducting ceramic heating element and control system

    NASA Technical Reports Server (NTRS)

    Halbach, C. R.; Page, R. J.

    1975-01-01

    Improvements were made in both electrode technology and ceramic conductor quality to increase significantly the lifetime and thermal cycling capability of electrically conducting ceramic heater elements. These elements were operated in vacuum, inert and reducing environments as well as oxidizing atmospheres adding to the versatility of the conducting ceramic as an ohmic heater. Using stabilized zirconia conducting ceramic heater elements, a furnace was fabricated and demonstrated to have excellent thermal response and cycling capability. The furnace was used to melt platinum-20% rhodium alloy (melting point 1904 C) with an isothermal ceramic heating element having a nominal working cavity size of 2.5 cm diameter by 10.0 cm long. The furnace was operated to 1940 C with the isothermal ceramic heating element. The same furnace structure was fitted with a pair of main heater elements to provide axial gradient temperature control over a working cavity length of 17.8 cm.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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%.

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

    SciTech Connect

    Youngblood, Gerald E.; Thomsen, Edwin C.; Henager, Charles H.

    2013-06-30

    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%.

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

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

    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.

  19. The bedrock electrical conductivity structure of Northern Ireland

    NASA Astrophysics Data System (ADS)

    Beamish, David

    2013-08-01

    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.

  20. Polyimide nanocomposites based on functionalized graphene sheets: Morphologies, thermal properties, and electrical and thermal conductivities

    NASA Astrophysics Data System (ADS)

    Heo, Cheol; Chang, Jin-Hae

    2013-10-01

    Polyimide (PI) films were prepared by reacting 4,4'-(4,4'-isopropylidene-diphenoxy)-bis(phthalic anhydride) and 1,3-bis(4-aminophenoxy)benzene. The 4-phenylbutylamine-functionalized graphene sheets (PBA-GSs) used for the preparation of the PI nanocomposite films were prepared by mixing a dispersion of graphite oxide with a solution of the ammonium salt of 4-phenylbutylamine (PBA). PI nanocomposite films containing different amounts of PBA-GS (0-10 wt%) were compared in terms of their morphologies, thermal properties, and electrical and thermal conductivities. Only a small amount of PBA-GS was required to improve the thermal properties and thermal conductivities of the PI; the maximum enhancements in these parameters were observed at 1 and 3 wt% PBA-GS, respectively. In contrast, the electrical conductivity of the PI hybrid films continued to increase with increasing PBA-GS content from 1 to 10 wt%.

  1. Testing and Optimization of Electrically Conductive Spacecraft Coatings

    NASA Technical Reports Server (NTRS)

    Mell, R. J.; Wertz, G. E.; Edwards, D. L. (Technical Monitor)

    2001-01-01

    This is the final report discussing the work done for the Space Environments and Effects (SEE) Program. It discusses test chamber design, coating research, and test results on electrically thermal control coatings. These thermal control coatings are being developed to have several orders of magnitude higher electrical conductivity than most available thermal control coatings. Most current coatings tend to have a range in surface resistivity from 1,011 to 1,013 ohms/sq. Historically, spacecraft have had thermal control surfaces composed of dielectric materials of either polymers (paints and metalized films) or glasses (ceramic paints and optical solar reflectors). Very seldom has the thermal control surface of a spacecraft been a metal where the surface would be intrinsically electrically conductive. The poor thermal optical properties of most metals have, in most cases, stopped them from being used as a thermal control surface. Metals low infrared emittance (generally considered poor for thermal control surfaces) and/or solar absorptance, have resulted in the use of various dielectric coatings or films being applied over the substrate materials in order to obtain the required optical properties.

  2. Electric conductivity from the solution of the relativistic Boltzmann equation

    NASA Astrophysics Data System (ADS)

    Puglisi, A.; Plumari, S.; Greco, V.

    2014-12-01

    We present numerical results of electric conductivity ?el of a fluid obtained solving the relativistic transport Boltzmann equation in a box with periodic boundary conditions. We compute ?el using two methods: the definition itself, i.e., applying an external electric field, and the evaluation of the Green-Kubo relation based on the time evolution of the current-current correlator. We find a very good agreement between the two methods. We also compare numerical results with analytic formulas in relaxation time approximation (RTA) where the relaxation time for ?el is determined by the transport cross section ?tr , i.e., the differential cross section weighted with the collisional momentum transfer. We investigate the electric conductivity dependence on the microscopic details of the two-body scatterings: isotropic and anisotropic cross section as well as massless and massive particles. We find that the RTA underestimates considerably ?el ; for example, at screening masses mD˜T , such underestimation can be as large as a factor of 2. Furthermore, we study a more realistic case for a quark-gluon system (QGP) considering both a quasiparticle model tuned to lattice QCD (lQCD) thermodynamics, as well as the case of a perturbative QCD (pQCD) gas with running coupling. Also, for these cases more directly related to the description of the QGP system, we find that the RTA significantly underestimates the ?el by about 60%-80%.

  3. DNA sequencing using electrical conductance measurements of a DNA polymerase

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Shiun; Lee, Chia-Hui; Hung, Meng-Yen; Pan, Hsu-An; Chiou, Jin-Chern; Huang, G. Steven

    2013-06-01

    The development of personalized medicine--in which medical treatment is customized to an individual on the basis of genetic information--requires techniques that can sequence DNA quickly and cheaply. Single-molecule sequencing technologies, such as nanopores, can potentially be used to sequence long strands of DNA without labels or amplification, but a viable technique has yet to be established. Here, we show that single DNA molecules can be sequenced by monitoring the electrical conductance of a phi29 DNA polymerase as it incorporates unlabelled nucleotides into a template strand of DNA. The conductance of the polymerase is measured by attaching it to a protein transistor that consists of an antibody molecule (immunoglobulin G) bound to two gold nanoparticles, which are in turn connected to source and drain electrodes. The electrical conductance of the DNA polymerase exhibits well-separated plateaux that are ~3 pA in height. Each plateau corresponds to an individual base and is formed at a rate of ~22 nucleotides per second. Additional spikes appear on top of the plateaux and can be used to discriminate between the four different nucleotides. We also show that the sequencing platform works with a variety of DNA polymerases and can sequence difficult templates such as homopolymers.

  4. Miniatuization of the flowing fluid electric conductivity loggingtec hnique

    SciTech Connect

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

    2005-10-19

    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.

  5. Improving the Electrical Conductivity of Polyaniline Through Molecular Control

    NASA Astrophysics Data System (ADS)

    Yoo, Joung Eun; Krekelberg, William; Bucholz, Tracy; Truskett, Thomas; Loo, Yueh-Lin

    2009-03-01

    We have investigated the electrical conductivity of polyaniline (PANI) that is template synthesized with a polymer acid of poly(2-acrylamido-2-methyl-1-propanesulfonic acid), PAAMPSA. The conductivity of PANI-PAAMPSA is determined by the particle density when PANI-PAAMPSA is cast as films. The PANI-PAAMPSA particle density can in turn be tuned by manipulating the molecular characteristics of PAAMPSA. Specifically, templating aniline polymerization with a higher molecular weight PAAMPSA results in bigger PANI-PAAMPSA particles; templating aniline polymerization with a broader molecular weight distribution PAAMPSA results in particles with a larger size distribution. The conductivity of drop-cast films of PANI-PAAMPSA therefore depends on how the particles pack in the solid state. In particular, we find the conductivity of PANI-PAAMPSA to increase with particle density. Additionally, PANI is preferentially segregated to the surface of these particles. The conductivity of PANI-PAAMPSA thus scales superlinearly with the surface area per unit volume of the cast film.

  6. Development of Tailorable Electrically Conductive Thermal Control Material Systems

    NASA Technical Reports Server (NTRS)

    Deshpande, M. S.; Harada, Y.

    1998-01-01

    The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has already added to the existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The object of this program was to develop two types of passive electrically conductive TCMS.

  7. Transparent electrical conducting films by activated reactive evaporation

    DOEpatents

    Bunshah, R.; Nath, P.

    1982-06-22

    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.

  8. Transparent electrical conducting films by activated reactive evaporation

    DOEpatents

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

    1982-01-01

    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.

  9. Measurements of middle-atmosphere electric fields and associated electrical conductivities

    NASA Technical Reports Server (NTRS)

    Hale, L. C.; Croskey, C. L.; Mitchell, J. D.

    1981-01-01

    A simple antenna for measuring the vertical electric field in the 'middle atmosphere' has been flown on a number of rocket-launched parachute-borne payloads. The data from the first nine such flights, launched under a variety of geophysical conditions, are presented, along with electrical conductivities measured simultaneously. The data include indications of layered peaks of several volts per meter in the mesospheric field at high and low latitudes in situations of relatively low conductivity. During an auroral 'REP' event the electric field reversed direction in the lower stratosphere, accompanied by a substantial enhancement in conductivity. The data generally do not confirm speculations based only on the extension of the thunderstorm circuit from below or the mapping of ionospheric and magnetospheric fields from above, but seem to require, in addition, internal generation processes in the middle atmosphere.

  10. Pore connectivity, electrical conductivity, and partial water saturation: Network simulations

    NASA Astrophysics Data System (ADS)

    Li, M.; Tang, Y. B.; Bernabé, Y.; Zhao, J. Z.; Li, X. F.; Bai, X. Y.; Zhang, L. H.

    2015-06-01

    The electrical conductivity of brine-saturated rock is predominantly dependent on the geometry and topology of the pore space. When a resistive second phase (e.g., air in the vadose zone and oil/gas in hydrocarbon reservoirs) displaces the brine, the geometry and topology of the pore space occupied by the electrically conductive phase are changed. We investigated the effect of these changes on the electrical conductivity of rock partially saturated with brine. We simulated drainage and imbibition as invasion and bond percolation processes, respectively, in pipe networks assumed to be perfectly water-wet. The simulations included the formation of a water film in the pipes invaded by the nonwetting fluid. During simulated drainage/imbibition, we measured the changes in resistivity index as well as a number of relevant microstructural parameters describing the portion of the pore space saturated with water. Except Euler topological number, all quantities considered here showed a significant level of "universality," i.e., insensitivity to the type of lattice used (simple cubic, body-centered cubic, or face-centered cubic). Hence, the coordination number of the pore network appears to be a more effective measure of connectivity than Euler number. In general, the simulated resistivity index did not obey Archie's simple power law. In log-log scale, the resistivity index curves displayed a substantial downward or upward curvature depending on the presence or absence of a water film. Our network simulations compared relatively well with experimental data sets, which were obtained using experimental conditions and procedures consistent with the simulations. Finally, we verified that the connectivity/heterogeneity model proposed by Bernabé et al. (2011) could be extended to the partial brine saturation case when water films were not present.

  11. Electrical conductivity and thermal dilepton rate from quenched lattice QCD

    E-print Network

    Olaf Kaczmarek; Anthony Francis

    2011-09-19

    We report on a continuum extrapolation of the vector current correlation function for light valence quarks in the deconfined phase of quenched QCD. This is achieved by performing a systematic analysis of the influence of cut-off effects on light quark meson correlators at $T\\simeq 1.45 T_c$ using clover improved Wilson fermions. We discuss resulting constraints on the electrical conductivity and the thermal dilepton rate in a quark gluon plasma. In addition new results at 1.2 and 3.0 $T_c$ will be presented.

  12. Electrical conductivity as an indicator of iron reduction rates in abiotic and biotic systems

    E-print Network

    Singha, Kamini

    Electrical conductivity as an indicator of iron reduction rates in abiotic and biotic systems Aaron; published 16 April 2011. [1] Although changes in bulk electrical conductivity (b) in aquifers have been. To explore the use of electrical conductivity to measure reaction rates, we conducted iron oxide reduction

  13. Electrical Modulation of the Local Conduction at Oxide Tubular Interfaces

    SciTech Connect

    Hsieh, Ying-Hui; Strelcov, Evgheni; Jia-Ming, Liou; Chia-Ying, Shen; Yi-Chun, Chen; Kalinin, Sergei V; Ying-Hao, Chu

    2013-01-01

    Hetero-interfaces between complex oxides have sparked considerable interest due to their fascinating physical properties and offer new possibilities for next-generation electronic devices. The key to realize practical applications is the control through external stimulus. In this study, we take the self-assembled BiFeO3-CoFe2O4 hetero-interface as a model system to demonstrate the non-volatile electric control of the local conduction at the complex oxide tubular interface. The fundamental mechanism behind this modulation was explored based on static and dynamic conducting atomic force microscopy. We found the movement of oxygen vacancies in the BiFeO3-CoFe2O4 heterostructure is the key to drive this intriguing behavior. This study delivers a possibility of designing new device for next-generation electronic devices.

  14. Interplanetary double-shock ensembles with anomalous electrical conductivity

    NASA Technical Reports Server (NTRS)

    Dryer, M.

    1972-01-01

    Similarity theory is applied to the case of constant velocity, piston-driven, shock waves. This family of solutions, incorporating the interplanetary magnetic field for the case of infinite electric conductivity, represents one class of experimentally observed, flare-generated shock waves. This paper discusses the theoretical extension to flows with finite conductivity (presumably caused by unspecified modes of wave-particle interactions). Solutions, including reverse shocks, are found for a wide range of magnetic Reynolds numbers from one to infinity. Consideration of a zero and nonzero ambient flowing solar wind (together with removal of magnetic considerations) enables the recovery of earlier similarity solutions as well as numerical simulations. A limited comparison with observations suggests that flare energetics can be reasonably estimated once the shock velocity, ambient solar wind velocity and density, and ambient azimuthal Alfven Mach number are known.

  15. Electrical conductivity of condensed molecular hydrogen in the giant planets

    NASA Technical Reports Server (NTRS)

    Smoluchowski, R.

    1972-01-01

    Theoretical interpretation of several phenomena concerning Jupiter and Saturn depends upon the electrical conductivity of molecular hydrogen which, according to present models, forms the outermost layer of both planets. The layer starts at the transition pressure between the metallic and the molecular form of hydrogen, that is around 1 Mbar, and extends to the outside limits of the atmosphere. Whether at the highest pressures (and temperatures) this layer is a solid or a dense fluid is not certain. In any case, the fluid is in supercritical condition so that there is only a gradual transition from dense liquid to a gaseous form. The two theories which require specific values of the conductivity of the condensed molecular hydrogen are those pertaining to the generation of a magnetic field in the liquid hydrogen rather than in the deep metallic interior (HIDE, 1967), and those concerned with the electromagnetic coupling and exchange of angular momentum between the liquid core and the solid molecular hydrogen mantle.

  16. Electrical conductivity of a boron plasma through the OCP crystallization

    NASA Astrophysics Data System (ADS)

    Lambert, F.; Mazevet, S.; Clérouin, J.

    2009-06-01

    We calculate the DC conductivity of a boron plasma along the 1 eV isotherm up to 25 times the normal density. We use both the quantum and Thomas Fermi molecular dynamics coupled with, respectively, the Kubo-Greenwood formulation and the semi-classical Ziman theory. We find that the DC conductivity obtained using a full quantum mechanical treatment exhibits a significant jump at the one component plasma phase transition - specifically the OCP crystallization of the ions - that is not reproduced using the semi-classical Ziman description. This difference - reaching up to a factor of four - remains well beyond the phase transition and up to the highest density explored. This shows that a full quantum mechanical treatment of the optical and electrical quantities is required in this regime even if semi-classical theories are reliable to obtain both the thermodynamical, and the ionic dynamical and structural properties.

  17. Electrically conductive PEDOT coating with self-healing superhydrophobicity.

    PubMed

    Zhu, Dandan; Lu, Xuemin; Lu, Qinghua

    2014-04-29

    A self-healing electrically conductive superhydrophobic poly(3,4-ethylenedioxythiophene) (PEDOT) coating has been prepared by chemical vapor deposition of a fluoroalkylsilane (POTS) onto a PEDOT film, which was obtained by electrochemical deposition. The coating not only maintained high conductivity with a low resistivity of 3.2 × 10(-4) ?·m, but also displayed a water contact angle larger than 156° and a sliding angle smaller than 10°. After being etched with O2 plasma, the coating showed an excellent self-healing ability, spontaneously regaining its superhydrophobicity when left under ambient conditions for 20 h. This superhydrophobicity recovery process was found to be humidity-dependent, and could be accelerated and completed within 2 h under a high humidity of 84%. The coating also exhibited good superhydrophobicity recovering ability after being corroded by strong acid solution at pH 1 or strong base solution at pH 14 for 3 h. PMID:24702588

  18. Electrical conduction in nanodomains in congruent lithium tantalate single crystal

    SciTech Connect

    Cho, Yasuo

    2014-01-27

    The electrical current flow behavior was investigated for nanodomains formed in a thin congruent lithium tantalate (LiTaO{sub 3}) single-crystal plate. When the nanodomains were relatively large, with diameters of about 100?nm, current flow was detected along the domain wall. However, when they were about 40?nm or smaller, the current flowed through the entire nanodomain. Schottky-like rectifying behavior was observed. Unlike the case of LiNbO{sub 3}, optical illumination was not required for current conduction in LiTaO{sub 3}. A clear temperature dependence of the current was found indicating that the conduction mechanism for nanodomains in LiTaO{sub 3} may involve thermally activated carrier hopping.

  19. Sound Waves, Thermal Conduction, and the Continuity Equation Carl Sovinec, T-15 LANL

    E-print Network

    Sovinec, Carl

    Sound Waves, Thermal Conduction, and the Continuity Equation Carl Sovinec, T-15 LANL 8 to sound waves when we use thermal conduction in our system of equations without continuity. The fluid definitions 0 02 p c , defining c as the adiabatic sound speed, kc 1 , the time for the adiabatic wave

  20. Stimulation of neurite outgrowth using an electrically conducting?polymer

    PubMed Central

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

    1997-01-01

    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-co-glycolic 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-co-glycolic acid). PMID:9256415

  1. Electrical conductivity of water-undersaturated crustal melting

    NASA Astrophysics Data System (ADS)

    Wannamaker, Philip E.

    1986-05-01

    Water-undersaturated melting in the crust can occur at lithostatic pressure in the presence of an H2O-CO2 fluid, of no CO2 or fluid but with all H2O bound structurally in hydrous minerals, or of an insufficient amount of H2O fluid to saturate a melt at liquidus temperatures. The composition of any fluid in equilibrium with possible source rocks depends on the metamorphic grade of the rocks; the fluid at lithostatic pressure in ductile granulite facies rocks would be CO2-rich, while an increased fraction of H2O in a fluid is probable in lithologies of lower metamorphic grade or in rocks of the brittle regime. With limited amounts of pore fluid and hydrous minerals, melting at constant pressure is a highly nonlinear function of temperature and may extend over a broad temperature range. Electrical conductivity of the resultant feldspathic liquids can be estimated to first order from early conductivity measurements on granite under conditions of excess water and recent theories on dissolution of H2O in aluminosilicate magmas. Experimental data suggest especially for the deep crust that conductivity of melt in equilibrium with its source residuum falls as melt fraction increases due to dilution of water in spite of increased temperature. At the lesser pressures of high-level magma chambers, pressure-temperature-water content relations of hydrous melt conductivity should be clarified by further laboratory examination. Melt fraction and temperature estimates derived from field electrical surveys are complicated seriously by melt phase tortuosity in the crystalline matrix, by H2O content of the source rock, and by the possibility of an H2O-CO2 fluid.

  2. Correlation Between Viscosity and Electrical Conductivity of Aluminosilicate Melts

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Hua; Chou, Kuo-Chih

    2012-08-01

    The linear relations between logarithm of viscosity and logarithm of electrical conductivity deduced in our previous paper for MO-SiO2 (M = Mg, Ca, Sr, Ba) and M2O-SiO2 (Li, Na, K) melts are extended in this study. It is found that the linear law for MO-SiO2 system is also followed for the melts of FeO-SiO2 and MnO-SiO2 (when electronic conduct can be neglected relative to ionic conduct). The relation between viscosity and electrical conductivity is mainly dependent on the valences of cations of basic oxides. For the sum {{{M}}x {{O-SiO}}2 } melt containing several basic oxides, there are two situations: In the case where all cations are divalent (or univalent), the relation is the same as that of MO-SiO2 melt (or M2O-SiO2 melt); in the case of existing both divalent and univalent cations, the coefficients for the linear relation can be calculated based on the coefficients of MO-SiO2 and M2O-SiO2 melts, with the weight factors from the renormalized mole fractions of sum {{MO}} and sum {{{M}}_{ 2} {{O}}} . It is also found that Al2O3 has little effect on the relation, and the law for sum {{{M}}_{{x}} {{O-SiO}}_{ 2} } melt can be approximately applied to sum {{{M}}_{{x}} {{O-Al}}_{ 2} {{O}}_{ 3} {{-SiO}}_{ 2} } melt.

  3. EFFECTS OF TRITIUM GAS EXPOSURE ON ELECTRICALLY CONDUCTING POLYMERS

    SciTech Connect

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

    2009-12-16

    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

  4. Effect of conductivity and concentration on the sample stream in the transverse axis of a continuous flow electrophoresis chamber

    NASA Technical Reports Server (NTRS)

    Miller, Teresa Y.; Williams, George O.; Snyder, Robert S.

    1985-01-01

    The resolution of continuous flow electrophoresis systems is generally measured by the spread of the sample bands in the direction of the electrophoretic migration. This paper evaluates the cross section of the sample bands in the plane perpendicular to the flow and shows that the spread in the direction perpendicular to the migration increased significantly with the applied electric field. Concentrated samples of monodisperse latex particles and vinyltoluene T-butylstyrene particles in sample buffers of different electrical conductivities were used to map the shape of the sample bands relative to the zero electric field case. As the electric field was applied, the sample band spread from an initial diameter of only one-third the chamber thickness until it approached the chamber walls where electroosmosis significantly reduced the resolution of separation. It can be shown, however, that it is possible to minimize these distortions by careful sample preparation and experiment design.

  5. Printability and Electrical Conductivity of UV Curable MWCNT Ink

    NASA Astrophysics Data System (ADS)

    Ortega, Ada; Park, Byungwoo; Kim, Nam Soo

    2015-03-01

    Composites reinforced with multiwalled carbon nanotubes (MWCNT) in a photosensitive acrylic matrix were successfully synthesized and their printing, rheological, and electrical behavior was characterized. The shape of the reinforcement MWCNT particles was analyzed by transmission electron microscopy. The MWCNT were mixed in the acrylic polymer at increasing concentrations until the percolation threshold was determined at 2 wt.% with a conductivity of 4.26 × 10-4 S/cm. The large increase in viscosity with addition of MWCNT showed the need for a printing system capable of dispensing solutions of up to 613 × 103 cp. Lines were printed with a precision dispensing system mounted in computer controlled x-y-z stages, while an integrated ultraviolet light emission diode dot with a single wavelength of 385 nm cured seconds after the ink was dispensed. The wetting properties of the composite with respect to polyester, polyethylene terephthalate, polyimide, and paper films were analyzed with a goniometer. The relationship between the contact angle, pattern accuracy, and electrical conductivity was determined for each substrate.

  6. Thermophysical Properties of Liquid Te: Density, Electrical Conductivity, and Viscosity

    NASA Technical Reports Server (NTRS)

    Li, C.; Su, C.; Lehoczky, S. L.; Scripa, R. N.; Ban, H.; Lin, B.

    2004-01-01

    The thermophysical properties of liquid Te, namely, density, electrical conductivity, and viscosity, were determined using the pycnometric and transient torque methods from the melting point of Te (723 K) to approximately 1150 K. A maximum was observed in the density of liquid Te as the temperature was increased. The electrical conductivity of liquid Te increased to a constant value of 2.89 x 10(exp 5 OMEGA-1m-1) as the temperature was raised above 1000 K. The viscosity decreased rapidly upon heating the liquid to elevated temperatures. The anomalous behaviors of the measured properties are explained as caused by the structural transitions in the liquid and discussed in terms of Eyring's and Bachiskii's predicted behaviors for homogeneous liquids. The Properties were also measured as a function of time after the liquid was coded from approximately 1173 or 1123 to 823 K. No relaxation phenomena were observed in the properties after the temperature of liquid Te was decreased to 823 K, in contrast to the relaxation behavior observed for some of the Te compounds.

  7. Magnetoresistance, electrical conductivity, and Hall effect of glassy carbon

    SciTech Connect

    Baker, D.F.

    1983-02-01

    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.

  8. 20 CFR 416.990 - When and how often we will conduct a continuing disability review.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... SUPPLEMENTAL SECURITY INCOME FOR THE AGED, BLIND, AND DISABLED Determining Disability and Blindness Continuing Or Stopping Disability Or Blindness § 416.990 When and how often we will conduct a continuing... continue to meet the disability or blindness requirements of the law. Payment ends if the medical or...

  9. 20 CFR 416.990 - When and how often we will conduct a continuing disability review.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... SUPPLEMENTAL SECURITY INCOME FOR THE AGED, BLIND, AND DISABLED Determining Disability and Blindness Continuing Or Stopping Disability Or Blindness § 416.990 When and how often we will conduct a continuing... continue to meet the disability or blindness requirements of the law. Payment ends if the medical or...

  10. Synthesis and applications of electrically conducting polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Ku, Bon-Cheol

    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.)

  11. Electrical Conductivity and Dielectric Studies of Hydraulic Cements

    NASA Astrophysics Data System (ADS)

    Pena, Marianela Perez

    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.

  12. Gellan gum-graft-polyaniline-An electrical conducting biopolymer.

    PubMed

    Karthika, J S; Vishalakshi, B; Naik, Jagadish

    2016-01-01

    Grafting of polyaniline (PANI) on to gellan gum (GG) was carried out in the presence of catalytic amount of ammonium peroxydisulfate (APS) as oxidant/initiator under mild acidic conditions by microwave irradiation technique. The grafting condition was optimized by varying the microwave power, exposure time and the composition of the reaction mixture. The graft copolymer GG-g-PANI was characterized by FTIR, TGA, UV/vis, (1)H NMR and SEM techniques. The characteristic peaks at 1506, 1462, 1070 and 830cm(-1) in the IR spectrum and signals at 7.3, 7.2, 7.1 and 4.0 ? in the (1)H NMR spectrum confirms the grafting process. The TGA data reveals GG-g-PANI to be thermally less stable than GG. The optimum grafting was observed when the reaction mixture containing 0.066mmol APS, 0.1M aniline, 1M hydrochloric acid and 0.1g/dL GG was exposed to 80W microwave power for 40s. The DC and AC conductivity of the GG-g-PANI were measured using the 'Two-point probe' method based on which the dielectric properties were evaluated. GG-g-PANI exhibited appreciable electrical conductivity, which increased with the extent of grafting. The results indicate threefold increase in DC conductivity of graft copolymer as compared to GG. PMID:26526174

  13. Lower Mantle Electrical Conductivity Based on Measurements of Al, Fe-Bearing Perovskite Under Lower Mantle Conditions

    NASA Astrophysics Data System (ADS)

    Sinmyo, R.; Pesce, G.; Greenberg, E.; McCammon, C. A.; Dubrovinsky, L. S.

    2014-12-01

    Laboratory measurements of the electrical conductivities of minerals provide important constraints on the chemistry and structure of the Earth's interior. We have measured the electrical conductivity of Al, Fe-bearing perovskite (Pv), the most abundant lower mantle phase, using a laser-heated diamond-anvil cell (LHDAC). The sample with composition Mg0.83Fe0.21Al0.06Si0.91O3 (Fe3+/?Fe ratio ~ 0.4) was synthesized at 26 GPa and 2073 K using a multianvil press. Sample resistance was measured in situ at high pressure and high temperature up to 82 GPa and 2000 K. Results show a continuous increase in electrical conductivity with increasing pressure, in contrast to some previous studies of (Mg,Fe)SiO3 perovskite and a pyrolite assemblage where a decrease in conductivity was observed at higher pressure. Our results suggest that (1) incorporation of aluminum in Pv has a strong effect on its electrical conductivity and evolution with pressure; (2) spin crossover of Fe3+ does not occur or its effect on the conductivity is small in Al, Fe-bearing Pv, and (3) the contribution of ferropericlase to the electrical conductivity of pyrolite may be significant. The electrical conductivity profile of the Earth's lower mantle derived from geomagnetic data can be better explained by a pyrolitic bulk chemical composition rather than a non-pyrolitic model such as one based solely on perovskite.

  14. Detection of Wheat Kernels with Hidden Insect Infestations Using an Electrically Conductive Roller Mill

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A laboratory roller mill system was modified to measure and analyze the electrical conductance of wheat as it was crushed. The electrical conductance of normal wheat kernels is normally low and fairly constant. In contrast, the electrical conductance of wheat kernels infested with live insects is su...

  15. Electrical Conduction in Native Deoxyribonucleic Acid: Hole Hopping Transfer Mechanism? Zdravko Kutnjak* and Cene Filipic

    E-print Network

    Podgornik, Rudolf

    Electrical Conduction in Native Deoxyribonucleic Acid: Hole Hopping Transfer Mechanism? Zdravko and frequency dependent electric conductivity below 1 MHz were carried out on wet-spun, macroscopically oriented to quasistatic time scales. The frequency dependence of the electrical conductivity in the frequency range

  16. Electrical conductivity of wadsleyite at high temperatures and high pressures Lidong Dai a,b

    E-print Network

    Electrical conductivity of wadsleyite at high temperatures and high pressures Lidong Dai a,b , Shun 2009 Editor: L. Stixrude Keywords: electrical conductivity wadsleyite oxygen fugacity frequency water The electrical conductivity of wadsleyite aggregates has been determined under the broad range of thermodynamic

  17. PPPL-3227, Preprint: January 1997, UC-426 MEASUREMENT OF THE HOT ELECTRICAL CONDUCTIVITY

    E-print Network

    PPPL-3227, Preprint: January 1997, UC-426 MEASUREMENT OF THE HOT ELECTRICAL CONDUCTIVITY IN THE PBX and the hot (power dependent) electrical conductivity. These can be simultaneously determined from a simple of the electrical conductivity [5]. This effect is related to the creation of a superthermal electron tail, and must

  18. PPPL3227, Preprint: January 1997, UC426 MEASUREMENT OF THE HOT ELECTRICAL CONDUCTIVITY

    E-print Network

    PPPL­3227, Preprint: January 1997, UC­426 MEASUREMENT OF THE HOT ELECTRICAL CONDUCTIVITY IN THE PBX and the hot (power dependent) electrical conductivity. These can be simultaneously determined from a simple of the electrical conductivity [5]. This effect is related to the creation of a superthermal electron tail, and must

  19. Electrically Conductive Metal Polymer Nanocomposites for Electronics Applications

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

    An electrically conductive nanocomposite composed of thermoplastic elastomer and nanosized silver particles was developed. Nanosized silver particles were produced by the liquid flame spraying method. Nanocomposites were produced employing a batch mixing process in the melt state. The percolation curve and the minimum resistivity as a function of silver content were defined. A plasticized styrene block-copolymer was used as the matrix polymer. The results showed that the agglomeration of the silver particles has a major influence on the percolation threshold and the resistivity of the compound. With slightly agglomerated silver particles a percolation threshold with a silver content of 13 16 vol.% was achieved. The corresponding resistivity was 2.0 × 10-1 ? cm. With heavily agglomerated particles the resistivity is high (2.9 × 103 ? cm), even with a silver content of 20 vol.%. With a low primary silver particle size (under 100 nm), the resistivity of the compound was high (5.6 × 105 ? cm).

  20. Electrically conductive, optically transparent polymer/carbon nanotube composites

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Jr., Joseph G. (Inventor); Harrison, Joycelyn S. (Inventor); Park, Cheol (Inventor); Watson, Kent A. (Inventor); Ounaies, Zoubeida (Inventor)

    2011-01-01

    The present invention is directed to the effective dispersion of carbon nanotubes (CNTs) into polymer matrices. The nanocomposites are prepared using polymer matrices and exhibit a unique combination of properties, most notably, high retention of optical transparency in the visible range (i.e., 400-800 nm), electrical conductivity, and high thermal stability. By appropriate selection of the matrix resin, additional properties such as vacuum ultraviolet radiation resistance, atomic oxygen resistance, high glass transition (T.sub.g) temperatures, and excellent toughness can be attained. The resulting nanocomposites can be used to fabricate or formulate a variety of articles such as coatings on a variety of substrates, films, foams, fibers, threads, adhesives and fiber coated prepreg. The properties of the nanocomposites can be adjusted by selection of the polymer matrix and CNT to fabricate articles that possess high optical transparency and antistatic behavior.

  1. System and method for determining velocity of electrically conductive fluid

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A. (Inventor); Korman, Valentin (Inventor); Markusic, Thomas E. (Inventor); Stanojev, Boris Johann (Inventor)

    2008-01-01

    A flowing electrically-conductive fluid is controlled between an upstream and downstream location thereof to insure that a convection timescale of the flowing fluid is less than a thermal diffusion timescale of the flowing fluid. First and second nodes of a current-carrying circuit are coupled to the fluid at the upstream location. A current pulse is applied to the current-carrying circuit so that the current pulse travels through the flowing fluid to thereby generate a thermal feature therein at the upstream location. The thermal feature is convected to the downstream location where it is monitored to detect a peak associated with the thermal feature so-convected. The velocity of the fluid flow is determined using a time-of-flight analysis.

  2. Electrical conductivity of quark matter at finite T

    E-print Network

    Seung-il Nam

    2012-11-01

    In this talk, I present the recent theoretical results on the electrical conductivity (EC) sigma of quark matter, using the Kubo formula at finite temperature and zero quark density (T>0, mu=0) in the presence of an external strong magnetic field. The dilute instanton-liquid model with the caloron distribution is taken into account. It turns out that sigma=(0.02~0.15)/fm for T=(0~400) MeV with the relaxation time tau=(0.3~0.9) fm. EC is parameterized as sigma/T (0.46,0.77,1.08,1.39)C_EM for tau=(0.3,0.5,0.7,0.9) fm, respectively. These results are well compatible with other theoretical estimations and show almost negligible effects from the magnetic field. The soft photon emission rate from the quark-gluon plasma is discussed as well.

  3. Electrical Conductivities and Optical Reflectivities of Dense Aluminum Plasmas

    NASA Astrophysics Data System (ADS)

    Blancard, C.; Desjarlais, M. P.; Faussurier, G.; Recoules, V.; Renaudin, P.

    2004-10-01

    We present a model to describe the thermodynamic and transport properties of dense plasmas. The electronic and ionic structures are determined self-consistently using finite temperature density functional theory and the Gibbs-Bogolyubov inequality. The main thermodynamic quantities, i.e., internal energy, pressure, entropy, and sound speed are obtained by numerical differentiation of the plasma total Helmholtz free energy. Electronic electrical and thermal conductivities are calculated from the Ziman approach. Ionic transport coefficients are estimated using those of a hard-sphere system and the Rosenfeld semi-empirical "universal" correspondence between excess entropy and dimensionless transport coefficients of dense fluids. Numerical results and comparisons with quantum molecular dynamics calculations and experiments are presented and discussed.

  4. Electrical Conductivities and Optical Reflectivities of Dense Aluminum Plasmas

    SciTech Connect

    Blancard, C.; Faussurier, G.; Recoules, V.; Renaudin, P.

    2004-10-20

    We present a model to describe the thermodynamic and transport properties of dense plasmas. The electronic and ionic structures are determined self-consistently using finite temperature density functional theory and the Gibbs-Bogolyubov inequality. The main thermodynamic quantities, i.e., internal energy, pressure, entropy, and sound speed are obtained by numerical differentiation of the plasma total Helmholtz free energy. Electronic electrical and thermal conductivities are calculated from the Ziman approach. Ionic transport coefficients are estimated using those of a hard-sphere system and the Rosenfeld semi-empirical 'universal' correspondence between excess entropy and dimensionless transport coefficients of dense fluids. Numerical results and comparisons with quantum molecular dynamics calculations and experiments are presented and discussed.

  5. Polymeric salt bridges for conducting electric current in microfluidic devices

    DOEpatents

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

    2009-11-17

    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.

  6. Lunar magnetic permeability, magnetic fields, and electrical conductivity temperature

    NASA Technical Reports Server (NTRS)

    Parkin, C. W.

    1978-01-01

    In the time period 1969-1972 a total of five magnetometers were deployed on the lunar surface during four Apollo missions. Data from these instruments, along with simultaneous measurements from other experiments on the moon and in lunar orbit, were used to study properties of the lunar interior and the lunar environment. The principal scientific results from analyses of the magnetic field data are discussed. The results are presented in the following main categories: (1) lunar electrical conductivity, temperature, and structure; (2) lunar magnetic permeability, iron abundance, and core size limits; (3) the local remnant magnetic fields, their interaction with the solar wind, and a thermoelectric generator model for their origin. Relevant publications and presented papers are listed.

  7. Electrical conductivity of intermediate magmas from Uturuncu Volcano (Bolivia)

    NASA Astrophysics Data System (ADS)

    Laumonier, Mickael; Gaillard, Fabrice; Sifre, David

    2015-04-01

    Magmas erupted at Uturuncu volcano (South Bolivia) comes from the Altiplano-Puna Magma Body (APMB, Chile-Bolivia), a crustal massive body of 80 km long by 10 km thick located at ~ 35 km depth named. Recent magneto telluric surveys reveal a resistivity lower than 1 ohm.m due to the presence of melt which could result in the reactivation of the volcano. In order to better constrain the resistivity profiles and thus the conditions of magma storage of the APMB, we have performed in situ electrical measurements on natural dacites and andesites from Uturuncu with a 4-wire set up in a piston cylinder and internally heated pressure vessel. The range of temperature (500 to 1300°C), pressure (0.3 to 2 Gpa), and the various water contents covers the respective ranges occurring at natural conditions. The results show that the conductivity increases with the temperature and the water content but slightly decreases with the pressure. Then a model was built from these results so as to help in (i) interpreting the electrical signature of natural magmas, (ii) constraining their conditions (chemical composition, temperature, pressure, water content, melt fraction) from the source to the storage location and (iii) providing information on the interior structure of a volcano and its reservoir.

  8. Electrical conductivity of carbonaceous chondrites and electric heating of meteorite parent bodies

    NASA Technical Reports Server (NTRS)

    Duba, AL

    1987-01-01

    Electromagnetic heating of rock-forming materials most probably was an important process in the early history of the solar system. Electrical conductivity experiments of representative materials such as carbonaceous chondrites are necessary to obtain data for use in electromagnetic heating models. With the assumption that carbon was present at grain boundaries in the material that comprised the meteorite parent bodies, the electrical heating of such bodies was calculated as a function of body size and solar distance using the T-Tauri model of Sonett and Herbert (1977). The results are discussed.

  9. Development of Tailorable Electrically Conductive Thermal Control Material Systems

    NASA Technical Reports Server (NTRS)

    Deshpande, M. S.; Harada, Y.

    1997-01-01

    The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and have been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties as well as mechanical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has added to already existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The objective of this program was to develop two types of passive electrically conductive TCMS. The first was a highly absorbing/emitting black surface and the second was a low (alpha(sub s)/epsilon(sub N)) type white surface. The surface resistance goals for the black absorber was 10(exp 4) to 10(exp 9) Omega/square, and for the white surfaces it was 10(exp 6) to 10(exp 10) Omega/square. Several material system concepts were suggested and evaluated for space environment stability and electrical performance characterization. Our efforts in designing and evaluating these material systems have resulted in several developments. New concepts, pigments and binders have been developed to provide new engineering quality TCMS. Some of these have already found application on space hardware, some are waiting to be recognized by thermal designers, and some require further detailed studies to become state-of-the-art for future space hardware and space structures. Our studies on baseline state-of-the-art materials and conductive concepts have resulted in several important findings that are of interest to all thermal designers and systems integrators.

  10. Measurement and Modeling the Atmospheric Electrical Conductivity for Monitoring the Air Pollution

    NASA Astrophysics Data System (ADS)

    Kamsali, Nagaraja; Datta, Jayati; Prasad, Bsn

    The electrical parameters such as ion mobility, small ion number density, and conductivity are important for understanding the electrical nature of the atmosphere. The small ions consisting of aggregates of a few molecules practically determine the electrical conductivity over the region. The number density of these ions is controlled by ionizing mechanisms for the production of ions and electrons, and the loss processes for these charged species. Ion - production is chiefly due to radioactive substances present in the Earth's crust and the cosmic rays coming from the extra - terrestrial origin, and the resulting electrons and positive ions rapidly undergo hydration reactions which lead to the formation of negative and positive molecular ion clusters referred to as ‘small ions'. Only singly charged ions are important since the cross section for the production of multiply charged ions by particle impact are smaller than those for the production of singly charged ions by an order of magnitude or more. Further, the multiply charged ions that are formed will rapidly undergo charge transfer reaction with neutral molecules to result in singly charged ions. The small ions have mobilities large enough to move appreciably under the influence of electric field and thus determine the electrical conductivity of the atmosphere. The equilibrium density of small ions (positive or negative) is governed by the equations of continuity for the production and loss of these ions, where the gain and loss due to transport are negligible. The effective recombination of small ions is altered in the presence of aerosols, since these aerosols interact with the ions through various attachment and recombination processes. The attachment of small ions to neutral aerosols produces charged aerosols referred to as ‘large ions', which are less mobile than the smaller molecular ions. The subsequent recombination of charged aerosols with ions as well as the oppositely charged aerosols would result in the depletion of small ion concentration more rapidly than in the absence of aerosols. Thus, the formation of less mobile aerosol ions and the reduction of more mobile molecular ions alter the electrical conductivity of atmosphere. Thus, the pollution due to aerosols/dust in the atmosphere can considerably reduce the atmospheric conductivity. Hence, the atmospheric pollution level can be monitored through electrical conductivity measurements and conductivity is used as index of air pollution. In an experimental programme at Pune (18N, 74E), India measurements of radon and its progeny, aerosol number density and atmospheric conductivity are measured over a period of time covering different seasons. Using the ionization rate, ambient aerosol density and meteorological parameters such as temperature, pressure and relative humidity, the small ion concentration and hence the conductivity of the atmosphere is estimated from an Ion-aerosol model. Model computed conductivity of the atmosphere is used to validate the measured conductivity from a Gerdien condenser setup. Also estimated from the model is the reduction in small ion concentration and hence the conductivity of the atmosphere for varying levels of aerosols. It is seen that for an increase of aerosols by 3 fold the percent reduction in conductivity is 7 %, and for an increase of aerosols by 6 fold the reduction in conductivity is 10 % from the pollution free atmosphere. These results are presented in the paper.

  11. High pressure-temperature electrical conductivity of magnesiowustite as a function of iron oxide concentration

    NASA Technical Reports Server (NTRS)

    Li, Xiaoyuan; Jeanloz, Raymond

    1990-01-01

    The electrical conductivity of (Mg, Fe)O magnesiowustite containing 9 and 27.5 mol pct FeO has been measured at simultaneously high pressures (30-32 GPa) and temperatures using a diamond anvil cell heated with a continuous wave Nd:YAG laser and an external resistance heater. The conductivity depends strongly on the FeO concentration at both ambient and high pressures. At the pressures and temperatures of about 30 GPa and 2000 K, conditions expected in the lower mantle, the magnesiowustite containing 27.5 percent FeO is 3 orders of magnitude more conductive than that containing 9 percent FeO. The activation energy of magnesiowustite decreases with increasing iron concentration from 0.38 (+ or - 0.09) eV at 9 percent FeO to 0.29 (+ or - 0.05) eV at 27.5 percent FeO.

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

    PubMed

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

    2012-05-17

    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

  13. Illuminating the electrical conductivity of the lowermost mantle from below

    NASA Astrophysics Data System (ADS)

    Jault, Dominique

    2015-07-01

    The magnetic field that originates in the earth's core is transformed across the electrically conducting mantle before being observed, at the earth's surface or above. Assuming that the conductivity depends only on radius, it has been customary to treat the mantle as a linear time-invariant filter for the core magnetic field, with properties (as a function of the frequency ?) specified by the transfer function ?(?). An high-frequency approximation to ?(?), which is derived from a three terms WKBJ expansion with ?-1/2 as small parameter, is found here to reproduce adequately, for low harmonic degrees and/or thin conducting layers, the exact solution, which is evaluated numerically. It is contrasted with the low-frequency estimation of ?, which consists in a perturbation procedure and in writing ?(?) as a series in powers of ? (? ? 0). The low-frequency theory is applied to the magnetic variations produced by the geostrophic core flows with about 6 yr period as the phase of these flows is independently determined from their effect on the length of the day. Apart from that, the low-frequency approximation overestimates the screening by the mantle of high-frequency signals, especially the low harmonic degree ones. In practice, the attenuating factor defined from the O(?2) term in the expansion of ? as ? ? 0 cannot be retrieved from analyses of geomagnetic time-series. Application of the mantle filter theory hinges on our knowledge about the time spectrum of the magnetic field at the core surface. The low-frequency theory had been previously applied to observatory series on the assumption that geomagnetic jerks occurring in the core are rare and isolated events. Rather than following up these earlier studies, I note that the spectral density function for the second time derivative of the main magnetic field coefficients is approximately independent of ? in a frequency range for which the mantle has undoubtedly negligible influence. In the absence of any other information, this scaling law is extrapolated to higher frequencies.

  14. Investigation of thermal conductivity, viscosity, and electrical conductivity of graphene based nanofluids

    NASA Astrophysics Data System (ADS)

    Kole, Madhusree; Dey, T. K.

    2013-02-01

    Stable and well dispersed functionalized graphene-ethylene glycol (EG) + distilled water nanofluids having graphene nano-sheets (GnS) volume concentration between 0.041 and 0.395 vol. % are prepared without any surfactant. Graphene nano-sheets are prepared from high purity graphite powder by Hummers method followed by exfoliation and reduction by hydrogen gas. Thus, obtained hydrogen exfoliated graphene (HEG) is then functionalized using acid. The graphene nano-sheets are characterized using XRD, TEM, Raman spectroscopy, and FTIR spectroscopy. Thermal conductivity and viscosity measurements are performed both as a function of graphene loading and temperature between 10 and 70 °C. Thermal conductivity enhancement of ˜15% for a loading of 0.395 vol. % f-HEG is observed at room temperature. The measured nanofluid's thermal conductivity is explained well in terms of the expression derived by Nan et al. (J. Appl. Phys. 81, 6692 (1997)), which considers matrix-additive interface contact resistance of mis-oriented ellipsoidal particles. The viscosity of the prepared f-HEG nanofluids and the base fluid (EG + distilled water) displays non-Newtonian behaviour with the appearance of shear thinning and nearly 100% enhancement compared to the base fluid (EG + DI water) with f-HEG loading of 0.395 vol. %. Known theoretical models for nanofluid's viscosity fail to explain the observed f-HEG volume concentration dependence of the nanofluid's viscosity. Temperature dependence of the studied nanofluid between 10 and 70 °C is explained well by the correlations proposed earlier for nanofluids with spherical nanoparticles. Electrical conductivity of the f-HEG nanofluids shows significant enhancement of ˜8620% for 0.395 vol. % loading of f-HEG in a base fluid of 70:30 mixture of EG and distilled water.

  15. Simultaneous remote electric and magnetic field measurements of lightning continuing currents

    E-print Network

    Cummer, Steven A.

    Simultaneous remote electric and magnetic field measurements of lightning continuing currents Manus in quasi-static electric fields have been most frequently used to remotely measure continuing current of continuing current signatures observed in both the quasi-static electric and magnetic fields from four

  16. Low-drag electrical contact arrangement for maintaining continuity between horizontally movable members

    DOEpatents

    Brown, R. Jack (Clinton, TN); Gerth, Howard L. (Knoxville, TN); Robinson, Samuel C. (Clinton, TN)

    1982-01-01

    This invention is a low-drag electrical contact arrangement for establishing continuity between upper and lower spaced members which are subject to relative horizontal movement. In one aspect, the invention comprises an electrical commutating arrangement which includes a horizontally disposed linear electrical commutator. A horizontally movable electrically conductive pedestal is positioned below the commutator and defines a clearance therewith. The pedestal is formed with a cavity confronting the commutator. In the cavity is a bead of electrical conductive liquid, the bead being characterized by an upwardly convex meniscus portion which extends across the clearance and contacts the commutator. The surface tension of the bead is sufficient to maintain the bead intact when the commutator and pedestal are displaced horizontally at speeds from zero to at least twelve inches a minute. This arrangement provides a significant advance in highly precise machining processes, such as diamond-turning, where precision is limited by the drag imposed by conventional commutators of the carbon-brush type.

  17. Low-drag electrical-contact arrangement for maintaining continuity between horizontally movable members

    DOEpatents

    Brown, R.J.; Gerth, H.L.; Robinson, S.C.

    1981-01-23

    This invention is a low-drag electrical contact arrangement for establishing continuity between upper and lower spaced members which are subject to relative horizontal movement. In one aspect, the invention comprises an electrical commutating arrangement which includes a horizontally disposed linear electrical commutator. A horizontally movable electrically conductive pedestal is positioned below the commutator and defines a clearance therewith. The pedestal is formed with a cavity confronting the commutator. In the cavity is a bead of electrical conductive liquid, the bead being characterized by an upwardly convex meniscus portion which extends across the clearance and contacts the commutator. The surface tension of the bead is sufficient to maintain the bead intact when the commutator and pedestal are displaced horizontally at speeds from zero to at least twelve inches a minute. This arrangement provides a significant advance in highly precise machining processes, such as diamond-turning, where precision is limited by the drag imposed by conventional commutators of the carbon-brush type.

  18. Electrical conduction and glass relaxation in alkali- silicate glasses

    NASA Astrophysics Data System (ADS)

    Angel, Paul William

    Electrical response measurements from 1 Hz to 1 MHz between 50o and 540oC were made on potassium, sodium and lithium-silicate glasses with low alkali oxide contents. Conductivity and electrical relaxation responses for both annealed and air quenched glasses of the same composition were compared. Quenching was found to lower the dc conductivity, ?dc, and activation energy as well as increase the pre-exponential term when compared to the corresponding annealed glass of the same composition. All of the glasses exhibited Arrhenius behavior in the log ?dc against 1/T plots. A sharp decrease in ?dc was observed for glasses containing alkali concentrations of 7 mol% or less. The ?dc activation energy exhibited similar behavior when plotted as a function of alkali composition and was explained in terms of a mixture of the weak and strong electrolyte models. The depression angle for fits to the complex impedance data were also measured as a function of thermal history, alkali concentration and alkali species. These results were interpreted in terms of changes in the distribution of relaxation times. Annealed samples from a single melt of a 10 mol% K2O-90SiO2 glass were reheated to temperatures ranging from 450o to 800oC, held isothermally for 20 min, and then quenched in either air or silicon oil. The complex impedance of both an annealed and the quenched samples were then measured as a function of temperature from 120o to 250oC. The ?dc was found to be remain unaffected by heat treatments below 450oC, to increase rapidly over an approximate 200oC range of temperatures that was dependent on cooling rate and to be constant for heat treatments above this range. This behavior is interpreted in terms of the mean structural relaxation time as a function of temperature and cooling rate near the glass transition temperature and glass transformation ranges. A more detailed definition for the transition and transformation temperatures and ranges was also provided.

  19. Design studies of continuously variable transmissions for electric vehicles

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Loewenthal, S. H.; Fischer, G. K.

    1981-01-01

    Preliminary design studies were performed on four continuously variable transmission (CVT) concepts for use with a flywheel equipped electric vehicle of 1700 kg gross weight. Requirements of the CVT's were a maximum torque of 450 N-m (330 lb-ft), a maximum output power of 75 kW (100 hp), and a flywheel speed range of 28,000 to 14,000 rpm. Efficiency, size, weight, cost, reliability, maintainability, and controls were evaluated for each of the four concepts which included a steel V-belt type, a flat rubber belt type, a toroidal traction type, and a cone roller traction type. All CVT's exhibited relatively high calculated efficiencies (68 percent to 97 percent) over a broad range of vehicle operating conditions. Estimated weight and size of these transmissions were comparable to or less than equivalent automatic transmission. The design of each concept was carried through the design layout stage.

  20. Enhanced Electrical Conductivity of Aluminum by Carbon Nanotube Hybrid Dilution

    NASA Astrophysics Data System (ADS)

    Stigers, Shelby; Savadelis, Alexader; Carruba, Kathryn; Johns, Kiley; Adu, Kofi

    2015-03-01

    Carbon nanotubes (CNTs) have been recognized as potential candidate for reinforcements in lightweight metals. A composite consisting of CNTs embedded in an Al-matrix might work as an ultra-low-resistive material with the potential of having a room-temperature resistivity far below Al, Cu and Ag. While several advances have been made in developing Al-CNT composites, three major challenges: (1) interfacial bond strength between CNT and the Al matrix, (2) homogeneous dispersion of the CNTs in the Al matrix and impurity (CNTs) scattering centers, continue to limit progress in Al-CNT composites. Several conventional methods including powder metallurgy, melting and solidification, thermal spray and electrochemical deposition have been used to process Al and CNT to form composites. We present preliminary results that address these challenges and demonstrate the fabrication of easily drawable Al-CNT composites into wires of diameter <= 1.0mm with ~ 18% +/- 2% reduction in the electrical resistivity of Al-CNT composite using CNT-hybrid as reinforcement and an inductive melting technique that takes advantage of the induced eddy current in the melt to provide in-situ stirring. This Work is Supported by Penn State Altoona Undergraduate Research Sponsored Program and Penn State Materials Research Institute, University Park.

  1. Highly Electrically Conducting Glass-Graphene Nanoplatelets Hybrid Coatings.

    PubMed

    Garcia, E; Nistal, A; Khalifa, A; Essa, Y; Martín de la Escalera, F; Osendi, M I; Miranzo, P

    2015-08-19

    Hybrid coatings consisting of a heat resistant Y2O3-Al2O3-SiO2 (YAS) glass containing 2.3 wt % of graphene nanoplatelets (GNPs) were developed by flame spraying homogeneous ceramic powders-GNP granules. Around 40% of the GNPs survived the high spraying temperatures and were distributed along the splat-interfaces, forming a percolated network. These YAS-GNP coatings are potentially interesting in thermal protection systems and electromagnetic interference shields for aerospace applications; therefore silicon carbide (SiC) materials at the forefront of those applications were employed as substrates. Whereas the YAS coatings are nonconductive, the YAS-GNP coatings showed in-plane electrical conductivity (?10(2) S·m(-1)) for which a low percolation limit (below 3.6 vol %) is inferred. Indentation tests revealed the formation of a highly damaged indentation zone showing multiple shear displacements between adjacent splats probably favored by the graphene sheets location. The indentation radial cracks typically found in brittle glass coatings are not detected in the hybrid coatings that are also more compliant. PMID:26222837

  2. Dependence of thermal conductivity on electrical resistivity in Bismuth Tellurides

    NASA Astrophysics Data System (ADS)

    Yamashita, Osamu; Satou, Kouji; Odahara, Hirotaka; Tomiyoshi, Shoichi

    2005-07-01

    The p-type (Bi0.25Sb0.75)2Te3 doped with 3 12 wt% excess Te alone and n-type Bi2(Te0.94Se0.06)3 codoped with 0.017 0.026 wt% Te and 0.068 0.102 wt% I were prepared by the Bridgman method, to produce intentionally polycrystalline. Some of the as-grown specimens were annealed, in order to prepare specimens with much different ?. These polycrystalline specimens have almost the same degree of alignment of the c plane parallel to the freezing direction. The electrical rersistivity ? and thermal conductivity ? were measured at 298 K along the freezing direction and ? was plotted as a function of ?. As a result, the lattice components ?ph obtained by subtracting the electronic component ?el from the observed ? were found to decrease almost linearly with a decrease of ? in both p- and n-type specimens, where ?el was calculated using Wiedemann Franz law. This tendency is consistent with the conventional result that ?ph becomes negligible small in metals. The significant decrease in ?ph with decrease in ? is considered to be caused predominantly by the phonon scattering due to dopants. The relationship between ?ph and ? was first clarified in the intermediate region between the metal and insulator.

  3. Analytic electrical-conductivity tensor of a nondegenerate Lorentz plasma.

    PubMed

    Stygar, W A; Gerdin, G A; Fehl, D L

    2002-10-01

    We have developed explicit quantum-mechanical expressions for the conductivity and resistivity tensors of a Lorentz plasma in a magnetic field. The expressions are based on a solution to the Boltzmann equation that is exact when the electric field is weak, the electron-Fermi-degeneracy parameter Theta>1, and the electron-ion Coulomb-coupling parameter Gamma/Z<1. (Gamma is the ion-ion coupling parameter and Z is the ion charge state.) Assuming a screened 1/r electron-ion scattering potential, we calculate the Coulomb logarithm in the second Born approximation. The ratio of the term obtained in the second approximation to that obtained in the first is used to define the parameter regime over which the calculation is valid. We find that the accuracy of the approximation is determined by Gamma/Z and not simply the temperature, and that a quantum-mechanical description can be required at temperatures orders of magnitude less than assumed by Spitzer [Physics of Fully Ionized Gases (Wiley, New York, 1962)]. When the magnetic field B=0, the conductivity is identical to the Spitzer result except the Coulomb logarithm ln Lambda(1)=(ln chi(1)-1 / 2)+[(2Ze(2)/lambdam(e)v(2)(e1))(ln chi(1)-ln 2(4/3))], where chi(1) identical with 2m(e)v(e1)lambda/ variant Planck's over 2pi, m(e) is the electron mass, v(e1) identical with (7k(B)T/m(e))(1/2), k(B) is the Boltzmann constant, T is the temperature, lambda is the screening length, variant Planck's over 2pi is Planck's constant divided by 2pi, and e is the absolute value of the electron charge. When the plasma Debye length lambda(D) is greater than the ion-sphere radius a, we assume lambda=lambda(D); otherwise we set lambda=a. The B=0 conductivity is consistent with measurements when Z greater, similar 1, Theta greater, similar 2, and Gamma/Z less, similar 1, and in this parameter regime appears to be more accurate than previous analytic models. The minimum value of ln Lambda(1) when Z> or =1, Theta> or =2, and Gamma/Z< or =1 is 1.9. The expression obtained for the resistivity tensor (B not equal 0) predicts that eta( perpendicular )/eta( parallel ) (where eta( perpendicular ) and eta( parallel ) are the resistivities perpendicular and parallel to the magnetic field) can be as much as 40% less than previous analytic calculations. The results are applied to an idealized 17-MA z pinch at stagnation. PMID:12443340

  4. Using electrical conductivity to monitor geothermal solute flux in major rivers of Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    McCleskey, R. B.; Mahony, D.; Lowenstern, J. B.; Heasler, H.; Nordstrom, D. K.

    2014-12-01

    Thermal output from the magma chamber underlying Yellowstone National Park (YNP) can be estimated by monitoring Cl flux in major rivers draining the park. The U.S. Geological Survey (USGS) and the National Park Service have collaborated on Cl flux monitoring towards this end since the 1970s. Researchers collected water samples from the major rivers in YNP, but funding restrictions, winter travel, and the great distances between sites limits the number of samples collected annually. The use of electrical conductivity, which is relatively easy to measure and can be automated, as a proxy for Cl enables a more consistent monitoring of thermal output. To accomplish this, it is crucial to accurately quantify the relationship between electrical conductivity, Cl, and other geothermal solutes (SO4, F, HCO3, SiO2, K, Li, B, and As) along the Madison, Firehole, Gibbon, Snake, Gardner, and Yellowstone Rivers. Conductivity measurements were made every 15 minutes adjacent to USGS stream gages, allowing for the determination of solute fluxes. In addition, continuous conductivity measurements can be used to identify changes in river chemistry as a result of geysers eruptions, rain events, or changes in thermal inputs as a result of earthquakes or other natural events. Depending on the site, we have collected 2 to 5 years of conductivity measurements. Except for some trace elements (Fe and Hg), most solutes behave conservatively, and the ratio of geothermal solute concentrations are constant. Hence, dissolved concentrations of Cl, SO4, F, HCO3, SiO2, K, Li, Ca, B, and As correlate well with conductivity (R2 > 0.96). The use of conductivity to estimate solute concentrations and fluxes will provide a greater understanding of the systematics of the Yellowstone thermal output and allow for monitoring of many more solutes at a much higher temporal frequency.

  5. High-strength carbon nanotube fibre-like ribbon with high ductility and high electrical conductivity.

    PubMed

    Wang, J N; Luo, X G; Wu, T; Chen, Y

    2014-01-01

    Macroscopic fibres made up of carbon nanotubes exhibit properties far below theoretical predictions and even much lower than those for conventional carbon fibres. Here we report improvements of mechanical and electrical properties by more than one order of magnitude by pressurized rolling. Our carbon nanotubes self-assemble to a hollow macroscopic cylinder in a tube reactor operated at high temperature and then condense in water or ethanol to form a fibre, which is continually spooled in an open-air environment. This initial fibre is densified by rolling under pressure, leading to a combination of high tensile strength (3.76-5.53 GPa), high tensile ductility (8-13%) and high electrical conductivity ((1.82-2.24) × 10(4) S cm(-1)). Our study therefore demonstrates strategies for future performance maximization and the very considerable potential of carbon nanotube assemblies for high-end uses. PMID:24964266

  6. Electrical conductivity of the lower-mantle ferropericlase across the electronic spin transition

    E-print Network

    Lin, Jung-Fu "Afu"

    Electrical conductivity of the lower-mantle ferropericlase across the electronic spin transition 2007. [1] Electrical conductivity of the lower-mantle ferropericlase-(Mg0.75,Fe0.25)O has been studied using designer diamond anvils to pressures over one megabar and temperatures up to 500 K. The electrical

  7. Electrical conductivity model of Al-bearing bridgmanite with implications for the electrical structure of the Earth's lower mantle

    NASA Astrophysics Data System (ADS)

    Yoshino, Takashi; Kamada, Seiji; Zhao, Chengcheng; Ohtani, Eiji; Hirao, Naohisa

    2016-01-01

    Electrical conductivity measurements of bridgmanite with various Al contents and a constant Mg# of 90 were performed at temperatures ranging from room temperature up to 2000 K at pressures of 26-28 GPa in a Kawai-type multianvil apparatus by impedance spectroscopy analysis. The incorporation of Al into bridgmanite raises its electrical conductivity significantly, but it is a small conductivity variation with respect to the quantity of Al. Synchrotron Mössbauer spectroscopy of recovered samples showed significant amounts of ferric iron in aluminous bridgmanite. The mobility of the charge carriers in bridgmanite was calculated based on the conductivity and the Fe3+/?Fe ratio. The relationship between the logarithm of the electrical conductivity and the reciprocal temperature is consistent with Fe2+-Fe3+ electron hopping (small polarons) as the dominant conduction mechanism at low temperatures (<1400 K) and ionic conduction at higher temperatures (>1600 K). By taking various conduction mechanisms into account, we develop an electrical conductivity model for aluminous bridgmanite as a function of the Al and Fe contents. The small polaron conduction model indicates that the electrical conductivity of aluminous bridgmanite has a maximum at around 0.06 Al atoms per formula unit, and any further increase in the Al content in bridgmanite reduces the conductivity. In contrast, the ionic conduction model indicates that the electrical conductivity simply increases with increasing Al content. The resulting conductivity of Al-bearing bridgmanite first increases up to 0.06 Al atoms per formula unit and then remains constant or increases with increasing Al content at higher temperatures. The increase in conductivity observed in the uppermost part of the lower mantle by electromagnetic studies can be explained by the gradual decomposition of majorite garnet. The deeper lower mantle conductivity would be controlled by small polaron conduction because of the large positive activation volume required for ionic conduction.

  8. The Wilkes subglacial basin eastern margin electrical conductivity anomaly

    NASA Astrophysics Data System (ADS)

    Rizzello, Daniele; Armadillo, Egidio; Ferraccioli, Fausto; Caneva, Giorgio

    2014-05-01

    We have analyzed the deep conductivity structure at the transition between the Transantarctic Mountains (TAM) and the eastern margin of the WSB in NVL, by means of the GDS (Geomagnetic Deep Sounding) technique, in order to constrain the geodynamical interpretation of this antarctic sector. The TAM form the uplifted flank of the Mesozoic and Cenozoic West Antarctic Rift System. Structure of the TAM rift flank has been partially investigated with different geophysical approaches.The Wilkes Subglacial Basin is a broad depression over 400 km wide at the George V Coast and 1200 km long. Geology, lithospheric structure and tectonics of the Basin are only partially known because the Basin is buried beneath the East Antarctic Ice Sheet and is located in a remote region which makes geophysical exploration logistically challenging. Different authors have proposed contrasting hypothesis regarding the origin of the WSB: it could represent a region of rifted continental crust, or it may have a flexural origin or might represent an "extended terrane". Recently aerogeophysical investigations have demonstrated a strong structural control on the margin. Magnetovariational studies carried out at high geomagnetic latitudes are often hampered by source effects, mainly due to the closeness to the Polar Electrojet currents systems (PEJ). Its presence, in fact, makes the uniform magnetic field assumption, on which the magnetovariational methods are based on, often invalid, which outcome is a bias in the GDS transfer functions and to compromise the reliability of the inverted models. Data from the aforementioned campaigns have been then processed under the ISEE project (Ice Sheet Electromagnetic Experiment), aimed at evaluate and mitigate the bias effect of the PEJ on geomagnetic an magnetotelluric transfer functions at high geomagnetic latitudes, by means of suitable processing algorithms, developed upon a statistical analysis study on PEJ effects (Rizzello et al. 2013). Recent results allowed for a new processing of a wide dataset acquired during three different international Antarctic campaigns supported by the Italian Antarctic Project: the BACKTAM, WIBEM and WISE expeditions. The qualitative analysis of the induction arrows, in the period range 20-170 s, reveals an approximately 2D regional electrical conductivity pattern with a clear differentiation between the three Terrains crossed by the GDS transect we have re-analized: the Robertson Bay, the Bowers and the Wilson Terrain. Bi-dimensional conductivity models, jointly with magnetic and gravimetric profiles, suggest a differentiation of the investigated area in three crustal sectors separated by the Daniels Range and the Bowers Mts., in close relation with main known structural lineaments; to the West, a deep conductivity anomaly is associated with the transition to the Wilkes Subglagial Basin. We deem that such anomaly, together with the magnetic and gravimetric signatures, is compatible with an extensional regime in the eastern margin of the WSB. References Rizzello, D., Armadillo, E., Manzella, A."Statistical analysis of the polar electrojet influence on geomagnetic transfer functions estimates, over wide time and space scales". EGU 2013 General Assembly, Wien - poster presentation.

  9. Double percolation in the electrical conduction in carbon fiber reinforced cement-based materials

    E-print Network

    Chung, Deborah D.L.

    Double percolation in the electrical conduction in carbon fiber reinforced cement-based materials Available online 9 November 2006 Abstract Electrically conductive cement-based materials are important conduction in carbon fiber cement-based materials. It involves fiber percolation and cement paste percolation

  10. The role of acids in electrical conduction through ice David E. Stillman,1

    E-print Network

    Stillman, David E.

    The role of acids in electrical conduction through ice David E. Stillman,1 Joseph A. MacGregor,2 from sea salt, biomass burning, and volcanic eruptions. The strongest conductivity response is to acids-boundary networks of unfrozen acids cause significant electrolytic conduction. Common electrical logs of ice cores

  11. Electrical conductivity of minerals and rocks Shun-ichiro Karato1

    E-print Network

    1 Electrical conductivity of minerals and rocks Shun-ichiro Karato1 and Duojun Wang1,2 1 : Yale-Blackwell #12;2 SUMMARY Electrical conductivity of most minerals is sensitive to hydrogen (water) content conductivity of major minerals has been characterized for most of the lower crust, upper mantle and transition

  12. Electrical conductivities of three-phase emulsions. 1. Strongly wetting middle phase

    SciTech Connect

    Smith, D.H. Univ. of Oklahoma, Norman, OK ); Johnson, G.K. ); Wang, Y.H.C.; Lim, K.H. )

    1994-08-01

    Electrical conductivities of steady-state, three-phase (macro)emulsions formed by the top (T), middle (M), and bottom (B) phases of the amphiphile/oil/[open quotes]water[close quotes] (i.e., aqueous 10 mM NaCl) system C[sub 4]H[sub 9]OC[sub 2]H[sub 4]OH/n-decane/water have been measured and compared with the predictions of equations from the literature or that we have proposed. In all cases the continuous phase could be deduced from the combination of experiment and theory, but less information was obtained about dispersed-phase structures. Three new conductivity equations and two new three-phase dispersion morphologies have been proposed. 30 refs., 8 figs., 2 tabs.

  13. Materials and methods for autonomous restoration of electrical conductivity

    SciTech Connect

    Blaiszik, Benjamin J; Odom, Susan A; Caruso, Mary M; Jackson, Aaron C; Baginska, Marta B; Ritchey, Joshua A; Finke, Aaron D; White, Scott R; Moore, Jeffrey S; Sottos, Nancy R; Braun, Paul V; Amine, Khalil

    2014-03-25

    An autonomic conductivity restoration system includes a solid conductor and a plurality of particles. The particles include a conductive fluid, a plurality of conductive microparticles, and/or a conductive material forming agent. The solid conductor has a first end, a second end, and a first conductivity between the first and second ends. When a crack forms between the first and second ends of the conductor, the contents of at least a portion of the particles are released into the crack. The cracked conductor and the released contents of the particles form a restored conductor having a second conductivity, which may be at least 90% of the first conductivity.

  14. Microstructural inhomogeneity of electrical conductivity in subcutaneous fat tissue.

    PubMed

    Kruglikov, Ilja L

    2015-01-01

    Microscopic peculiarities stemming from a temperature increase in subcutaneous adipose tissue (sWAT) after applying a radio-frequency (RF) current, must be strongly dependent on the type of sWAT. This effect is connected with different electrical conductivities of pathways inside (triglycerides in adipocytes) and outside (extra-cellular matrix) the cells and to the different weighting of these pathways in hypertrophic and hyperplastic types of sWAT. The application of the RF current to hypertrophic sWAT, which normally has a strongly developed extracellular matrix with high concentrations of hyaluronan and collagen in a peri-cellular space of adipocytes, can produce, micro-structurally, a highly inhomogeneous temperature distribution, characterized by strong temperature gradients between the peri-cellular sheath of the extra-cellular matrix around the hypertrophic adipocytes and their volumes. In addition to normal temperature effects, which are generally considered in body contouring, these temperature gradients can produce thermo-mechanical stresses on the cells' surfaces. Whereas these stresses are relatively small under normal conditions and cannot cause any direct fracturing or damage of the cell structure, these stresses can, under some supportive conditions, be theoretically increased by several orders of magnitude, causing the thermo-mechanical cell damage. This effect cannot be realized in sWAT of normal or hyperplastic types where the peri-cellular structures are under-developed. It is concluded that the results of RF application in body contouring procedures must be strongly dependent on the morphological structure of sWAT. PMID:25734656

  15. Microstructural Inhomogeneity of Electrical Conductivity in Subcutaneous Fat Tissue

    PubMed Central

    Kruglikov, Ilja L.

    2015-01-01

    Microscopic peculiarities stemming from a temperature increase in subcutaneous adipose tissue (sWAT) after applying a radio-frequency (RF) current, must be strongly dependent on the type of sWAT. This effect is connected with different electrical conductivities of pathways inside (triglycerides in adipocytes) and outside (extra-cellular matrix) the cells and to the different weighting of these pathways in hypertrophic and hyperplastic types of sWAT. The application of the RF current to hypertrophic sWAT, which normally has a strongly developed extracellular matrix with high concentrations of hyaluronan and collagen in a peri-cellular space of adipocytes, can produce, micro-structurally, a highly inhomogeneous temperature distribution, characterized by strong temperature gradients between the peri-cellular sheath of the extra-cellular matrix around the hypertrophic adipocytes and their volumes. In addition to normal temperature effects, which are generally considered in body contouring, these temperature gradients can produce thermo-mechanical stresses on the cells’ surfaces. Whereas these stresses are relatively small under normal conditions and cannot cause any direct fracturing or damage of the cell structure, these stresses can, under some supportive conditions, be theoretically increased by several orders of magnitude, causing the thermo-mechanical cell damage. This effect cannot be realized in sWAT of normal or hyperplastic types where the peri-cellular structures are under-developed. It is concluded that the results of RF application in body contouring procedures must be strongly dependent on the morphological structure of sWAT. PMID:25734656

  16. Effective zero-thickness model for a conductive membrane driven by an electric field

    E-print Network

    Bazant, Martin Z.

    The behavior of a conductive membrane in a static (dc) electric field is investigated theoretically. An effective zero-thickness model is constructed based on a Robin-type boundary condition for the electric potential at ...

  17. High thermal conductivity connector having high electrical isolation

    DOEpatents

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

    1995-01-01

    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.

  18. Evaluation of saline tracer performance during electrical conductivity groundwater monitoring

    NASA Astrophysics Data System (ADS)

    Mastrocicco, Micòl; Prommer, Henning; Pasti, Luisa; Palpacelli, Stefano; Colombani, Nicolò

    2011-04-01

    Saline solutions are the most commonly used hydrological tracers, because they can be easily and economically monitored by in situ instrumentation such as electrical conductivity (EC) loggers in wells or by geoelectrical measurements. Unfortunately, these low-cost techniques only provide information on the total concentration of ions in solution, i.e., they cannot resolve the ionic composition of the aqueous solution. This limitation can introduce a bias in the estimation of aquifer parameters where sorption phenomena between saline tracers and sediments become relevant. In general, only selected anions such as Cl - and Br - are recognised to be transported unretarded and they are referred to as conservative tracers or mobile anions. However, cations within the saline tracer may interact with the soil matrix through a range of processes such as ion exchange, surface complexation and via physical mass-transfer phenomena. Heterogeneous reactions with minerals or mineral surfaces may not be negligible where aquifers are composed of fine alluvial sediments. The focus of the present study was to examine and to quantify the bias between the aquifer parameters estimated during model-based interpretation of experimental data of EC measurements of saline tracer relative to the aquifer parameters found by specific measurements (i.e. via ionic chromatography, IC) of truly conservative species. To accomplish this, column displacement experiments with alluvial aquifer materials collected from the Po lowlands (Italy) were performed under water saturated conditions. The behaviour of six selected, commonly used saline tracers (i.e., LiCl, KCl, and NaCl; LiBr, KBr, and NaBr) was studied and the data analysed by inverse modelling. The results demonstrate that the use of EC as a tracer can lead to an erroneous parameterisation of the investigated porous media, if the reactions between solute and matrix are neglected. In general, errors were significant except for KCl and KBr, which is due to the weak interaction between dissolved K + and the sediment material. The study shows that laboratory scale pre-investigations can help with tracer selection and to optimise the concentration range targeted for in situ multilevel monitoring by unspecific geoelectrical instrumentation.

  19. Study of electrical conductivity response upon formation of ice and gas hydrates from salt solutions by a second generation high pressure electrical conductivity probe

    NASA Astrophysics Data System (ADS)

    Sowa, Barbara; Zhang, Xue Hua; Kozielski, Karen A.; Dunstan, Dave E.; Hartley, Patrick G.; Maeda, Nobuo

    2014-11-01

    We recently reported the development of a high pressure electrical conductivity probe (HP-ECP) for experimental studies of formation of gas hydrates from electrolytes. The onset of the formation of methane-propane mixed gas hydrate from salt solutions was marked by a temporary upward spike in the electrical conductivity. To further understand hydrate formation a second generation of window-less HP-ECP (MkII), which has a much smaller heat capacity than the earlier version and allows access to faster cooling rates, has been constructed. Using the HP-ECP (MkII) the electrical conductivity signal responses of NaCl solutions upon the formation of ice, tetrahydrofuran hydrates, and methane-propane mixed gas hydrate has been measured. The concentration range of the NaCl solutions was from 1 mM to 3M and the driving AC frequency range was from 25 Hz to 5 kHz. This data has been used to construct an "electrical conductivity response phase diagrams" that summarize the electrical conductivity response signal upon solid formation in these systems. The general trend is that gas hydrate formation is marked by an upward spike in the conductivity at high concentrations and by a drop at low concentrations. This work shows that HP-ECP can be applied in automated measurements of hydrate formation probability distributions of optically opaque samples using the conductivity response signals as a trigger.

  20. Anisotropy of synthetic quartz electrical conductivity at high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Wang, Duojun; Li, Heping; Yi, Li; Matsuzaki, Takuya; Yoshino, Takashi

    2010-09-01

    AC measurements of the electrical conductivity of synthetic quartz along various orientations were made between 0.1 and 1 MHz, at ˜855˜1601 K and at 1.0 GPa. In addition, the electrical conductivity of quartz along the c axis has been studied at 1.0-3.0 GPa. The impedance arcs representing bulk conductivity occur in the frequency range of 103-106 Hz, and the electrical responses of the interface between the sample and the electrode occur in the 0.1˜103 Hz range. The pressure has a weak effect on the electrical conductivity. The electrical conductivity experiences no abrupt change near the ? - ? phase transition point. The electrical conductivity of quartz is highly anisotropic; the electrical conductivity along the c axis is strongest and several orders of magnitude larger than in other directions. The activation enthalpies along various orientations are determined to be 0.6 and 1.2 eV orders of magnitude, respectively. The interpretation of the former is based on the contribution of alkali ions, while the latter effect is attributed to additional unassociated aluminum ions. Comparison of determined anisotropic conductivity of quartz determined with those from field geophysical models shows that the quartz may potentially provide explanations for the behavior of electrical conductivity of anisotropy in the crust that are inferred from the transverse magnetic mode.

  1. Density Functional Theory of the Electrical Conductivity of Molecular Devices Kieron Burke,1

    E-print Network

    Burke, Kieron

    the conductance. At finite fields, the KS Green's function is significantly distorted from its zero-field valueDensity Functional Theory of the Electrical Conductivity of Molecular Devices Kieron Burke,1 conductivity is shown to match the adiabatic conductivity, thereby recovering the Landauer result. DOI: 10

  2. J. Geomag. Geoelectr., 45, 707728, 1993 Constraints on Mantle Electrical Conductivity

    E-print Network

    Key, Kerry

    J. Geomag. Geoelectr., 45, 707­728, 1993 Constraints on Mantle Electrical Conductivity from Field in the sense of minimum first and second derivatives of log(conductivity) with log(depth) show conductivities these conductivities using a laboratory model for the temperature dependence of dry sub- solidus olivine yield

  3. Physical modeling of electrical conduction in printed circuit board insulation

    E-print Network

    Sarathy, Vasanth

    2005-01-01

    This thesis is concerned with understanding the degradation of electrical and electronic components in automobiles due to environmental effects. A special emphasis is placed on understanding the physical processes underlying ...

  4. Electrical conductivity of polyvinyl alcohol-multiwall carbon nanotubes composites

    NASA Astrophysics Data System (ADS)

    Amrin, Sayed; Deshpande, V. D.

    2013-06-01

    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).

  5. Phase Diagrams of Electric-Fduced Aggregation in Conducting Colloids

    NASA Technical Reports Server (NTRS)

    Khusid, B.; Acrivos, A.

    1999-01-01

    Under the application of a sufficiently strong electric field, a suspension may undergo reversible phase transitions from a homogeneous random arrangement of particles into a variety of ordered aggregation patterns. The surprising fact about electric-field driven phase transitions is that the aggregation patterns, that are observed in very diverse systems of colloids, display a number of common structural features and modes of evolution thereby implying that a universal mechanism may exist to account for these phenomena. It is now generally believed that this mechanism emanates from the presence of the long-range anisotropic interactions between colloidal particles due to their polarization in an applied field. But, in spite of numerous applications of the electric-field-driven phenomena in biotechnology, separation, materials engineering, chemical analysis, etc. our understanding of these phenomena is far from complete. Thus, it is the purpose of the proposed research to develop a theory and then test experimentally, under normal- and low-gravity conditions, the accuracy of the theoretical predictions regarding the effect of the synergism of the interparticle electric and hydrodynamic interactions on the phase diagram of a suspension. The main results from our theoretical studies performed to-date enable one to trace how the variations of the electrical properties of the constituent materials influence the topology of the suspension phase diagram and then, by using an appropriate phase diagram, to evaluate how the electric-field-induced transformations will depend on the frequency and the strength of the applied field.

  6. Preparation of Electrically Conductive Polystyrene/Carbon Nanofiber Nanocomposite Films

    ERIC Educational Resources Information Center

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

    2008-01-01

    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…

  7. Thermal and electrical conduction in the compaction direction of exfoliated graphite

    E-print Network

    Chung, Deborah D.L.

    Thermal and electrical conduction in the compaction direction of exfoliated graphite of the compaction and graphite layer preferred orientation on the thermal and electrical conductions in the compaction direction of graphite-flake-based exfoliated graphite have been decoupled. The compact

  8. Soil permittivity response to bulk electrical conductivity for selected soil water sensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bulk electrical conductivity can dominate the low frequency dielectric loss spectrum in soils, masking changes in the real permittivity and causing errors in estimated water content. We examined the dependence of measured apparent permittivity (Ka) on bulk electrical conductivity in contrasting soil...

  9. POTENTIAL IRRIGATION APPLICATIONS USING SENSOR-BASED APPARENT SOIL ELECTRICAL CONDUCTIVITY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Apparent soil electrical conductivity (ECa) is a measure of a soil's ability to conduct an electrical charge and can be obtained quickly for mapping purposes using on-the-go sensors. Several important soil properties, important for irrigation management, have been successfully related to soil ECa. I...

  10. Electrical Conductivity Of Diamond Up To 1,200 Degrees C

    NASA Technical Reports Server (NTRS)

    Vandersande, Jan W.; Zoltan, Leslie D.

    1993-01-01

    Report discusses measurements of electrical conductivities of two synthetic diamond films, three synthetic diamondlike films, and two natural type IIa diamonds at temperatures from ambient to 1,200 degrees C. Measurements performed to compare electrical conductivities of state-of-the-art diamond films with those of natural insulating diamond, particularly at temperatures above 700 degrees C.

  11. Base metal alloys with self-healing native conductive oxides for electrical contact materials

    E-print Network

    Alpay, S. Pamir

    Base metal alloys with self-healing native conductive oxides for electrical contact materials M 30 July 2010; accepted 15 September 2010; published online 12 October 2010 Base metals for electrical to unacceptably high contact resistances. Here we show that alloying base metals can lead to higher conductivity

  12. 76 FR 75875 - Plan for Conduct of 2012 Electric Transmission Congestion Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-05

    ... workshops and request for written comments in connection with the preparation of a study of electric transmission congestion pursuant to section 216(a)(1) of the Federal Power Act (76 FR 70122). This document... Conduct of 2012 Electric Transmission Congestion Study AGENCY: Office of Electricity Delivery and...

  13. Local electrical conduction in polycrystalline La-doped BiFeO3 thin films

    NASA Astrophysics Data System (ADS)

    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

    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.

  14. High performance heat curing copper-silver powders filled electrically conductive adhesives

    NASA Astrophysics Data System (ADS)

    Cui, Hui-Wang; Jiu, Jin-Ting; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki; Uchida, Hiroshi

    2015-03-01

    In this study, high performance electrically conductive adhesives were fabricated from a vinyl ester resin, a thermal initiator, silver coated copper powders, and pure silver powders, without using any other coupling agent, dispersing agent, and reducing agent. The heat cured copper-silver powders filled electrically conductive adhesives presented low bulk resistivity (e.g., 4.53 × 10-5 ?·cm) due to the silver powders that had given high electrical conductivity to the adhesives, and high shear strength (e.g., 16.22 MPa) provided by the crosslinked structures of vinyl ester resin. These high performance copper-silver powders filled electrically conductive adhesives have lower cost than those filled by pure silver powders, which can be well used in the electronic packaging and can enlarge the application prospects of electrically conductive adhesives. [Figure not available: see fulltext.

  15. Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

    PubMed Central

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

    2011-01-01

    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. PMID:21505445

  16. Electrical conductivity of cobalt-titanium substituted SrCaM hexaferrites

    NASA Astrophysics Data System (ADS)

    Eraky, M. R.

    2012-03-01

    A series of polycrystalline M-type hexagonal ferrites with the composition Sr0.5Ca0.5CoxTixFe12-2xO19 (where x=0.0-0.8) were prepared by the conventional ceramic technique. The electrical conductivity has been measured from 300 to 590 K. The dc conductivity, ?dc, exhibited a semiconductor behavior. The negative sign of thermoelectric power coefficient S reveals that all samples are n-type semiconductors. Both ?dc and mobility, ?d, increases with the substitution of Co2+ and Ti4+ ions, reach maximum at x=0.4 and start decreasing at x>0.4. Many conduction mechanisms were discussed to explain the electric conduction in the system. It was found that the hopping conduction is the predominant conduction mechanism. For samples with compositional parameter x=0.0 and 0.8, the band conduction mechanism shares in electric conduction beside the hopping process.

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

    SciTech Connect

    Sheftman, D.; Krasik, Ya. E.

    2011-09-15

    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.

  18. Influence of matching solubility parameter of polymer matrix and CNT on electrical conductivity of CNT/rubber composite

    PubMed Central

    Ata, Seisuke; Mizuno, Takaaki; Nishizawa, Ayumi; Subramaniam, Chandramouli; Futaba, Don N.; Hata, Kenji

    2014-01-01

    We report a general approach to fabricate elastomeric composites possessing high electrical conductivity for applications ranging from wireless charging interfaces to stretchable electronics. By using arbitrary nine kinds of rubbers as matrices, we experimentally demonstrate that the matching the solubility parameter of CNTs and the rubber matrix is important to achieve higher electrical conductivity in CNT/rubber composite, resulting in continuous conductive pathways leading to electrical conductivities as high as 15?S/cm with 10 vol% CNT in fluorinated rubber. Further, using thermodynamic considerations, we demonstrate an approach to mix CNTs to arbitrary rubber matrices regardless of solubility parameter of matrices by adding small amounts of fluorinated rubber as a polymeric-compatibilizer of CNTs. We thereby achieved electrical conductivities ranging from 1.2 to 13.8?S/cm (10 vol% CNTs) using nine varieties of rubber matrices differing in chemical structures and physical properties. Finally, we investigated the components of solubility parameter of CNT by using Hansen solubility parameters, these findings may useful for controlling solubility parameter of CNTs. PMID:25434701

  19. Influence of matching solubility parameter of polymer matrix and CNT on electrical conductivity of CNT/rubber composite.

    PubMed

    Ata, Seisuke; Mizuno, Takaaki; Nishizawa, Ayumi; Subramaniam, Chandramouli; Futaba, Don N; Hata, Kenji

    2014-01-01

    We report a general approach to fabricate elastomeric composites possessing high electrical conductivity for applications ranging from wireless charging interfaces to stretchable electronics. By using arbitrary nine kinds of rubbers as matrices, we experimentally demonstrate that the matching the solubility parameter of CNTs and the rubber matrix is important to achieve higher electrical conductivity in CNT/rubber composite, resulting in continuous conductive pathways leading to electrical conductivities as high as 15 S/cm with 10 vol% CNT in fluorinated rubber. Further, using thermodynamic considerations, we demonstrate an approach to mix CNTs to arbitrary rubber matrices regardless of solubility parameter of matrices by adding small amounts of fluorinated rubber as a polymeric-compatibilizer of CNTs. We thereby achieved electrical conductivities ranging from 1.2 to 13.8 S/cm (10 vol% CNTs) using nine varieties of rubber matrices differing in chemical structures and physical properties. Finally, we investigated the components of solubility parameter of CNT by using Hansen solubility parameters, these findings may useful for controlling solubility parameter of CNTs. PMID:25434701

  20. Influence of matching solubility parameter of polymer matrix and CNT on electrical conductivity of CNT/rubber composite

    NASA Astrophysics Data System (ADS)

    Ata, Seisuke; Mizuno, Takaaki; Nishizawa, Ayumi; Subramaniam, Chandramouli; Futaba, Don N.; Hata, Kenji

    2014-12-01

    We report a general approach to fabricate elastomeric composites possessing high electrical conductivity for applications ranging from wireless charging interfaces to stretchable electronics. By using arbitrary nine kinds of rubbers as matrices, we experimentally demonstrate that the matching the solubility parameter of CNTs and the rubber matrix is important to achieve higher electrical conductivity in CNT/rubber composite, resulting in continuous conductive pathways leading to electrical conductivities as high as 15 S/cm with 10 vol% CNT in fluorinated rubber. Further, using thermodynamic considerations, we demonstrate an approach to mix CNTs to arbitrary rubber matrices regardless of solubility parameter of matrices by adding small amounts of fluorinated rubber as a polymeric-compatibilizer of CNTs. We thereby achieved electrical conductivities ranging from 1.2 to 13.8 S/cm (10 vol% CNTs) using nine varieties of rubber matrices differing in chemical structures and physical properties. Finally, we investigated the components of solubility parameter of CNT by using Hansen solubility parameters, these findings may useful for controlling solubility parameter of CNTs.

  1. Electrical conductivity in directionally solidified lead-9 and -20 wt pct copper alloys

    NASA Technical Reports Server (NTRS)

    Kim, Shinwoo; Flanagan, W. F.; Lichter, B. D.; Grugel, R. N.

    1993-01-01

    Composites consisting of aligned copper dendrites in a lead matrix have been produced by directional solidification processing for potential application as grids in lead-acid batteries. To promote a uniform composite of aligned copper dendrites in a protective lead matrix, two alloy compositions, Pb-9 and -20 wt pct Cu, have been directionally solidified through a temperature gradient of 4.5 K/mm at constant growth velocities which ranged from 1 to 100 micron/s. With slow growth rates (below about 10 microns/s), the copper dendrites were generally columnar and continuous along the sample length; at higher velocities (above 60 microns/s), they assumed an intricate and equiaxed morphology. In accordance with copper content and growth rate, the electrical conductivity of the directionally solidified composites was found to be as much as a 2.5 times that of pure lead. The results are compared with that predicted by a model based on a geometrical dendrite.

  2. Highly Electrically Conductive Nanocomposites Based on PolymerInfused Graphene Sponges

    PubMed Central

    Li, Yuanqing; Samad, Yarjan Abdul; Polychronopoulou, Kyriaki; Alhassan, Saeed M.; Liao, Kin

    2014-01-01

    Conductive polymer composites require a threedimensional 3D network to impart electrical conductivity. A general method that is applicable to most polymers for achieving a desirable graphene 3D network is still a challenge. We have developed a facile technique to fabricate highly electrical conductive composite using vacuumassisted infusion of epoxy into graphene sponge GS scaffold. Macroscopic GSs were synthesized from graphene oxide solution by a hydrothermal method combined with freeze drying. The GSepoxy composites prepared display consistent isotropic electrical conductivity around 1Sm, and it is found to be close to that of the pristine GS. Compared with neat epoxy, GSepoxy has a 12ordersofmagnitude increase in electrical conductivity, attributed to the compactly interconnected graphene network constructed in the polymer matrix. This method can be extended to other materials to fabricate highly conductive composites for practical applications such as electronic devices, sensors, actuators, and electromagnetic shielding. PMID:24722145

  3. The role of electronic and ionic conduction in the electrical conductivity of carbon fiber reinforced cement

    E-print Network

    Chung, Deborah D.L.

    reinforced cement Sihai Wen, D.D.L. Chung * Composite Materials Research Laboratory, University at Buffalo, State University of New York, Buffalo, NY 14260-4400, USA Received 12 January 2006; accepted 13 March conduction. In the wet state (water saturated state), ionic conduction dominates. When silica fume is present

  4. Electrical Characterization and Morphological Studies of Conducting Polymer Nanofibers

    NASA Technical Reports Server (NTRS)

    Pinto, N. J.; Zhou, Y. X.; Freitag, M.; Johnson, A. T.; MacDiarmid, A. G.; Mueller, C. H.; Theofylaktos, N.; Robinson, D. C.; Miranda, F. A.

    2003-01-01

    Doped polyaniline blended with poly(ethylene oxide) has been electrospun in air to give fibers with diameters in the range 3 nm 200 nm. These fibers were captured on wafers of degenerately doped Si/SiO2 by placing the wafer in the path of the fiber jet formed during the electrospinning process. Individual fibers were contacted using shadow mask evaporation and were also captured on prepatterned wafers. Fibers having diameters greater than 100 nm show a slight increase in the conductivity as compared to the bulk film, while fibers with diameters less than 30 nm had lower conductivity than the bulk. Data on Scanning Conductance Microscopy along the length of individual fibers will be presented. For fibers where the diameter was not uniform, we found that below a certain diameter ( approx.15 nm) the fiber was less conducting as compared to thicker diameter fibers. Dependence of the fiber conductivity on a gate bias is underway and these results will also be presented.

  5. Lorentz force sigmometry: a novel technique for measuring the electrical conductivity of solid and liquid metals

    NASA Astrophysics Data System (ADS)

    Alkhalil, Shatha; Kolesnikov, Yurii; Thess, André

    2015-11-01

    In this paper, a novel method to measure the electrical conductivity of solid and molten metals is described. We term the method ‘Lorentz force sigmometry’, where the term ‘sigmometry’ refers to the letter sigma ?, often used to denote the electrical conductivity. The Lorentz force sigmometry method is based on the phenomenon of eddy currents generation in a moving conductor exposed to a magnetic field. Based on Ampere’s law, the eddy currents in turn generate a secondary magnetic field; as a result, the Lorentz force acts to brake the conductor. Owing to Newton’s third law, a measurable force, which is equal to the Lorentz force and is directly proportional to the electrical conductivity of the conductive fluid or solid, acts on the magnet. We present the results of the measurements performed on solids along with the initial measurements on fluids with a eutectic alloy composition of Ga67In20.5Sn12.5; detailed measurements on molten metals are still in progress and will be published in the future. We conducted a series of experiments and measured the properties of known electrical conductive metals, including aluminum and copper, to compute the calibration factor of the device, and then used the same calibration factor to estimate the unknown electrical conductivity of a brass bar. The predicted electrical conductivity of the brass bar was compared with the conductivity measured with a commercial device called ‘SigmaTest’ the observed error was less than 0.5%.

  6. Continuous glucose monitoring microsensor with a nanoscale conducting matrix and redox mediator

    NASA Astrophysics Data System (ADS)

    Pesantez, Daniel

    The major limiting factor in kidney clinical transplantation is the shortage of transplantable organs. The current inability to distinguish viability from non-viability on a prospective basis represents a major obstacle in any attempt to expand organ donor criteria. Consequently, a way to measure and monitor a relevant analyte to assess kidney viability is needed. For the first time, the initial development and characterization of a metabolic microsensor to assess kidney viability is presented. The rate of glucose consumption appears to serve as an indicator of kidney metabolism that may distinguish reversible from irreversible kidney damage. The proposed MetaSense (Metabolic Sensor) microdevice would replace periodic laboratory diagnosis tests with a continuous monitor that provides real-time data on organ viability. Amperometry, a technique that correlates an electrical signal with analyte concentration, is used as a method to detect glucose concentrations. A novel two-electrode electrochemical sensing cell design is presented. It uses a modified metallic working electrode (WE) and a bare metallic reference electrode (RE) that acts as a pseudo-reference/counter electrode as well. The proposed microsensor has the potential to be used as a minimally invasive sensor for its reduced number of probes and very small dimensions achieved by micromachining and lithography. In order to improve selectivity of the microdevice, two electron transfer mechanisms or generations were explored. A first generation microsensor uses molecular oxygen as the electron acceptor in the enzymatic reaction and oxidizes hydrogen peroxide (H2O2) to get the electrical signal. The microsensor's modified WE with conductive polymer polypyrrole (PPy) and corresponding enzyme glucose oxidase (GOx) immobilized into its matrix, constitutes the electrochemical detection mechanism. Photoluminescence spectroscopic analysis confirmed and quantified enzyme immobilized concentrations within the matrix. In vitro testing for glucose shows increasing current with increasing analyte concentration. Testing the glucose microsensor with known concentrations of glucose over a period of 48 hours demonstrated both the potential durability and sensitivity of the device. Unknown/blind in vitro glucose experiments showed the reproducibility and accuracy of the microsensor to detect various glucose levels. Thinner polymer matrix films lead to better sensing performance during in vitro tests (0.6nA/mM lower limit sensitivity and 0.2nA/mM upper limit sensitivity). In vitro experiments using electroactive ascorbic acid (AA) and uric acid (UA) showed the selectivity of the sensor for glucose. In an effort to reduce the sensor's oxidation potential (0.7V) and noise, a second generation electron transfer approach was developed by incorporating into a modified Platinum WE with a nanoscale PPy and GOx matrix, a redox mediator. Ferrocene (Fc) was selected as the artificial electron carrier, substituting molecular oxygen in the enzymatic reaction. The incorporation of Fc into the polymer matrix is done by a simple electrochemical synthesis. Modifications in the microsensor design, materials and fabrication process are presented. Experiments with the new sensor generation resulted in higher sensitivity values (22.8nA/mM lower limit sensitivity and 12.5nA/mM upper limit sensitivity) for glucose and noise was further eliminated by operating the sensor at a lower oxidation potential (0.3V). The final experimental work consisted of preliminary ex vivo tests with the MetaSense microdevice on bovine kidney samples, which showed a qualitatively correlation between glucose consumption trend profile during preservation and viability histology outcome.

  7. A transient hot-wire instrument for thermal conductivity measurements in electrically conducting liquids at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Alloush, A.; Gosney, W. B.; Wakeham, W. A.

    1982-09-01

    This paper describes a novel type of transient hot-wire cell for thermal conductivity measurements on electrically conducting liquids. A tantalum wire of 25 ?m. diameter is used as the sensing element in the cell, and it is insulated from the conducting liquids by an anodic film of tantalum pentoxide, 70 nm thick. The cell is suitable for measurements on conducting liquids at elevated temperatures. The results of test measurements on liquid water at its saturation vapor pressure are reported in order to confirm the correct operation of the thermal conductivity cell. The data, which have an estimated accuracy of ±3%, depart by less than ±1.8% from the correlation proposed by the International Association for the Properties of Steam. Results are also presented for concentrated aqueous solutions of lithium bromide, which are frequently used in absorption refrigerator cycles.

  8. A CONTINUED INVESTIGATION OF ELECTRICALLY STIMULATED FABRIC FILTRATION

    EPA Science Inventory

    The report summarizes three experiments performed by Southern Research Institute under a cooperative agreement with EPA. First was a demonstration of electrostatically stimulated fabric filtration (ESFF) used to collect particulate matter (PM) from fossil fuel electrical power pl...

  9. Electrical Conductivity of 2D-SiCf/CVI-SiC

    SciTech Connect

    Youngblood, Gerald E.; Thomsen, Edwin C.; Shinavski, Robert J.

    2011-07-11

    Electrical conductivity (EC) data for several plate forms of two-dimensional, silicon carbide composite made with chemical vapor infiltration matrix and with Hi Nicalon{trademark} type S fibers (2D-SiCf/CVI-SiC) were acquired. The composite fibers were coated with pyrocarbon (PyC) of various thicknesses (50 to 310 nm) and an outer thin ({approx}60 {mu}m) SiC 'seal coat' was applied by CVD to the infiltrated plates. The EC was highly anisotropic in the transverse and in-plane directions. In-plane EC ranged from {approx}150 to 1600 S/m, increased slowly with increasing temperature, and depended primarily on the total PyC thickness. High in-plane EC-values occur because it is dominated by conduction along the numerous, continuous PyC fiber coating pathways. Transverse EC ranged from {approx}1 to 60 S/m, and increased strongly with increasing temperature up to 800 C. The transverse EC is controlled by conduction through the interconnections of the carboncoating network within and between fiber bundles, especially at moderate temperatures ({approx}300 to 700 C). Below {approx}300 C, the electrical resistance of the pure SiC seal coat becomes increasingly more important as temperatures are further lowered. Importantly, a '3-layer series' model predicts that transverse EC-values for a standard seal-coated 2DSiCf/ CVI-SiC with a monolayer PyC fiber coating of {approx}50-nm thickness will be <20 S/m for all temperatures up to 800 C, as desired for a flow channel insert in a fusion reactor blanket component.

  10. Electrical conductivity of mantle in the North Central region of Nigeria

    NASA Astrophysics Data System (ADS)

    Obiora, Daniel N.; Okeke, Francisca N.; Yumoto, K.

    2015-01-01

    The mantle electrical conductivity profile of the North Central region of Nigeria was determined using the quiet day ionospheric current variations (Sq). The employed magnetic averaged hourly data were obtained from Magnetic Data Acquisition System (MAGDAS) ground based observatories at two Nigerian stations located at Ilorin (8°30?N, 4°33?E) and Abuja (8°59?N, 7°23?E) for the year 2009 and 2010. The magnetometer data from Pankshin (9°20?N, 9°27?E) and Katsina-Ala (7°10?N, 9°17?E) for the same years were equally employed. The separation of both the internal and external field contributions to the Sq variations was successfully carried out employing spherical harmonic analysis (SHA). Transfer function was performed in computing the conductivity-depth profile for North Central region of Nigeria from the paired external and internal coefficients of the SHA. The conductivity value of approximately 0.039 S/m was estimated at a depth of 100 km which rose gradually to 0.087 S/m at 207 km depth and 0.142 S/m at 367 km (close to the base of upper mantle). Subsequently, the conductivity profile continued rising to a value of 0.144 S/m at 442 km, 0.164 S/m at 653 km and 0.174 S/m at 710 km. Finally, value of approximately 0.195 S/m at a depth of 881 km and 0.240 S/m at 1100 km depth were recorded at the lower mantle with no indication of leveling off. Some evidence of discontinuities near 100-214 km, 214-420 km, 420-640 km, 640-900 km and 900-1100 km were clearly obvious. The sharp increase in conductivity from about 100 km depth to 230 km was interpreted to correspond to the global seismic low velocity zone - the asthenosphere.

  11. Simultaneous Modeling of Thermopower and Electrical Conduction in Olivine Steven Constable1

    E-print Network

    Key, Kerry

    Simultaneous Modeling of Thermopower and Electrical Conduction in Olivine Steven Constable1 Abstract. Measurements of conductivity and thermopower as a function of oxygen fu- gacity (fO2 ) are used to derive a model for conduction in olivine. Thermopower at 1000­ 1200 C is between 50 and 400 µV/K and has

  12. Capacitive conductivity logging and electrical stratigraphy in a high-resistivity aquifer, Boise Hydrogeophysical Research Site

    E-print Network

    Barrash, Warren

    Capacitive conductivity logging and electrical stratigraphy in a high-resistivity aquifer, Boise a prototype capacitive-conductivity borehole tool in a shallow, unconfined aquifer with coarse, unconsoli- dated sediments and very-low-conductivity water at the Boi- se Hydrogeophysical Research Site BHRS

  13. Electrical conductivity of quark matter in magnetic field

    E-print Network

    B. Kerbikov; M. Andreichikov

    2011-12-05

    Fermion currents in dense quark matter embedded into magnetic field are under intense discussions motivated by Chiral Magnetic Effect. We argue that conductivity of quark matter may be independent of the magnetic field direction and not proportional to the magnetic field strength.

  14. Electrically Conductive Bulk Composites through a Contact-Connected Aggregate

    PubMed Central

    Nawroj, Ahsan I.; Swensen, John P.; Dollar, Aaron M.

    2013-01-01

    This paper introduces a concept that allows the creation of low-resistance composites using a network of compliant conductive aggregate units, connected through contact, embedded within the composite. Due to the straight-forward fabrication method of the aggregate, conductive composites can be created in nearly arbitrary shapes and sizes, with a lower bound near the length scale of the conductive cell used in the aggregate. The described instantiation involves aggregate cells that are approximately spherical copper coils-of-coils within a polymeric matrix, but the concept can be implemented with a wide range of conductor elements, cell geometries, and matrix materials due to its lack of reliance on specific material chemistries. The aggregate cell network provides a conductive pathway that can have orders of magnitude lower resistance than that of the matrix material - from 1012 ohm-cm (approx.) for pure silicone rubber to as low as 1 ohm-cm for the silicone/copper composite at room temperature for the presented example. After describing the basic concept and key factors involved in its success, three methods of implementing the aggregate into a matrix are then addressed – unjammed packing, jammed packing, and pre-stressed jammed packing – with an analysis of the tradeoffs between increased stiffness and improved resistivity. PMID:24349239

  15. Influence of pressure and temperature on the electrical conductivity of dolomite

    NASA Astrophysics Data System (ADS)

    Ono, Shigeaki; Mibe, Kenji

    2015-10-01

    The electrical conductivity of dolomite, (Mg, Ca)CO3, was investigated under conditions of 650-1000 K and 3-6 GPa with a multi-anvil press and an impedance spectroscopy analyzer with a frequency range of 0.05-106 Hz. As pressure increased, an increase in the electrical conductivity and a decrease in the calculated activation enthalpy were observed. The negative activation volume observed in this study suggests that the hopping of polarons is the dominant mechanism for the electrical conductivity across the pressure and temperature range investigated. This mechanism is the same as that of magnesite, MgCO3, which has the similar structure of dolomite. In contrast, the mechanism of the ionic conduction was reported in aragonite, CaCO3. These results indicate that the mechanism for the electrical conductivity of carbonate minerals varies because of a crystallographic difference between the calcite- and the aragonite-type structure.

  16. Influence of pressure and temperature on the electrical conductivity of dolomite

    NASA Astrophysics Data System (ADS)

    Ono, Shigeaki; Mibe, Kenji

    2015-06-01

    The electrical conductivity of dolomite, (Mg, Ca)CO3, was investigated under conditions of 650-1000 K and 3-6 GPa with a multi-anvil press and an impedance spectroscopy analyzer with a frequency range of 0.05-106 Hz. As pressure increased, an increase in the electrical conductivity and a decrease in the calculated activation enthalpy were observed. The negative activation volume observed in this study suggests that the hopping of polarons is the dominant mechanism for the electrical conductivity across the pressure and temperature range investigated. This mechanism is the same as that of magnesite, MgCO3, which has the similar structure of dolomite. In contrast, the mechanism of the ionic conduction was reported in aragonite, CaCO3. These results indicate that the mechanism for the electrical conductivity of carbonate minerals varies because of a crystallographic difference between the calcite- and the aragonite-type structure.

  17. An electrical conductivity inspection methodology of polycrystalline diamond cutters

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    The polycrystalline diamond cutter (PDC) is widely used in oil and gas drilling operations. It is manufactured by sintering diamond powder onto a tungsten carbide substrate at 6 GPa and 1500 C. During sintering, molten cobalt from the substrate infiltrates the diamond table. The residual metal content correlates with cutter performance. We present an instrument that employs electrical impedance tomography capable of imaging the 3D metal content distribution in the diamond table. These images can be used to predict cutter performance as well as detect flaws.

  18. Transparent electrically conducting thin films for spacecraft temperature control applications

    NASA Technical Reports Server (NTRS)

    Hass, G.; Heaney, J. B.; Toft, A. R.

    1979-01-01

    Thin transparent films of In2O3 or In2O3 + SnO2 prepared by evaporation or sputtering have been tested for use as surface layers for spacecraft temperature control coatings. The films are intended to prevent nonuniform electric charge buildup on the spacecraft exterior. Film thicknesses of 300 to 500 A were found to be optimal in terms of durability and minimum impact on the solar absorptance and the thermal emissivity of the underlayers. As a verification of their suitability for long-duration space missions, the films were subjected to simulated solar UV plus proton irradiation in a vacuum.

  19. Electrical conductivity of electrolytes applicable to natural waters from 0 to 100 degrees C

    USGS Publications Warehouse

    McCleskey, R. Blaine

    2011-01-01

    The electrical conductivities of 34 electrolyte solutions found in natural waters ranging from (10-4 to 1) mol?kg-1 in concentration and from (5 to 90) °C have been determined. High-quality electrical conductivity data for numerous electrolytes exist in the scientific literature, but the data do not span the concentration or temperature ranges of many electrolytes in natural waters. Methods for calculating the electrical conductivities of natural waters have incorporated these data from the literature, and as a result these methods cannot be used to reliably calculate the electrical conductivity over a large enough range of temperature and concentration. For the single-electrolyte solutions, empirical equations were developed that relate electrical conductivity to temperature and molality. For the 942 molar conductivity determinations for single electrolytes from this study, the mean relative difference between the calculated and measured values was 0.1 %. The calculated molar conductivity was compared to literature data, and the mean relative difference for 1978 measurements was 0.2 %. These data provide an improved basis for calculating electrical conductivity for most natural waters.

  20. Nanostructured Cu-Cr alloy with high strength and electrical conductivity

    SciTech Connect

    Islamgaliev, R. K. Nesterov, K. M.; Bourgon, J.; Champion, Y.; Valiev, R. Z.

    2014-05-21

    The influence of nanostructuring by high pressure torsion (HPT) on strength and electrical conductivity in the Cu-Cr alloy has been investigated. Microstructure of HPT samples was studied by transmission electron microscopy with special attention on precipitation of small chromium particles after various treatments. Effect of dynamic precipitation leading to enhancement of strength and electrical conductivity was observed. It is shown that nanostructuring leads to combination of high ultimate tensile strength of 790–840?MPa, enhanced electrical conductivity of 81%–85% IACS and thermal stability up to 500?°C. The contributions of grain refinement and precipitation to enhanced properties of nanostructured alloy are discussed.

  1. Electrical conduction of LiF interlayers in organic diodes

    NASA Astrophysics Data System (ADS)

    Bory, Benjamin F.; Gomes, Henrique L.; Janssen, René A. J.; de Leeuw, Dago M.; Meskers, Stefan C. J.

    2015-04-01

    An interlayer of LiF in between a metal and an organic semiconductor is commonly used to improve the electron injection. Here, we investigate the effect of moderate bias voltages on the electrical properties of Al/LiF/poly(spirofluorene)/Ba/Al diodes by systematically varying the thickness of the LiF layer (2-50 nm). Application of forward bias V below the bandgap of LiF (V < Eg ˜ 14 V) results in reversible formation of an electrical double layer at the LiF/poly(spirofluorene) hetero-junction. Electrons are trapped on the poly(spirofluorene) side of the junction, while positively charged defects accumulate in the LiF with number densities as high as 1025/m3. Optoelectronic measurements confirm the built-up of aggregated, ionized F centres in the LiF as the positive trapped charges. The charged defects result in efficient transport of electrons from the polymer across the LiF, with current densities that are practically independent of the thickness of the LiF layer.

  2. Electrical conductivity and Equation of State from Measurements of a Tamped Electrically Exploded Foil

    NASA Astrophysics Data System (ADS)

    Ruden, Edward; Amdahl, David; Cooksey, Rufus; Domonkos, Matthew; Robinson, Paul; Analla, Francis; Brown, Darwin; Kostora, Mark; Camacho, Frank

    2013-10-01

    Results are presented for an experiment that produces and diagnoses dynamic surface conditions of homogeneous warm dense matter (WDM) to infer intrinsic bulk properties such as density, pressure, temperature, specific energy, electrical conductivity, and emissivity in the ranges of up to few eV and down to 0.1 solid density-typical of those encountered in single shot pulsed power device electrodes. The goal is to validate ab initio models of matter encountered for predictive modeling of such devices. In the test whose results are presented here, the WDM is produced by Ohmically heating and exploding an 80 ?m Al foil placed between two fused quartz tampers by the discharge of a 36 ?F capacitor bank charged to 30.1 kV and discharged in 2.55 ?s to a peak load current of 460 kA. Measurements are presented from two division of amplitude polarimeters which operate at 532 nm and 1064 nm, a complementary pyrometer which measures the spectral radiance ratio at those wavelengths, a long-range 660 nm photonic Doppler velocimeter, and a B-dot probe array from which the aforementioned intrinsic properties may be inferred. Available results are compared to a 3-D MHD ALEGRA simulation of the full dynamic load and return conductor geometry with a two-loop external coupled circuit.

  3. Rate dependence of electrical and mechanical properties of conductive polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Foley, J. R.; Stilson, C. L.; Smith, K. K. G.; McKinion, C. M.; Chen, C.; Ganguli, S.; Roy, A. K.

    2015-09-01

    Conductive polymer nanocomposites with enhanced electrical and thermal properties show promise as an alternative solution for electronic materials. For example, electronic interconnect materials will have comparable electrical and thermal conductivity to solder with an increased operating range of strain and temperature. This paper documents the fabrication and experimental evaluation of a prototype conductive polymer nanocomposite. Material selection, fabrication processes, and initial characterization of a low Tg polymer with a high fill ratio of carbon nanotubes is presented. The electrical and thermal properties of the composite are measured and compared with predictions. The mechanical properties are measured using dynamic mechanical analysis (DMA) over a wide temperature range. The mechanical and electrical responses of the conductive polymer composite are simultaneously measured at higher strain rates using a modified split Hopkinson pressure bar (SHPB) apparatus. The dynamic stress-strain response is obtained using traditional analytic methods (e.g., two- and three-wave analysis). The electrical response is observed using constant current excitation with high bandwidth (>500 kHz) instrumentation. The dynamic compression data implies the change in electrical resistance is solely a function of the material deformation, i.e., the material exhibits constant electrical conductivity and is insensitive to the applied loads. DMA and SHPB dynamic data are used to estimate the parameters in a Mulliken-Boyce constitutive model, and the resulting behavior is critically evaluated. Finally, progress towards improving the polymer composite's mechanical, electrical, and thermal properties are discussed.

  4. Polymer/Pristine Graphene Based Composites: From Emulsions to Strong, Electrically Conducting Foams

    NASA Astrophysics Data System (ADS)

    Woltornist, Steven; Carrillo, Jan-Michael; Xu, Thomas; Dobrynin, Andrey; Adamson, Douglas

    2015-03-01

    The unique electrical, thermal and mechanical properties of graphene make it a perfect candidate for applications in graphene/graphite based polymer composites, yet challenges due to the lack of solubility of pristine graphene/graphite in water, common organic solvents, and polymer solutions and melts have limited its practical utilization. Here we report a scalable and environmentally friendly technique to form water-in-oil type emulsions stabilized by a graphitic skin consisting of overlapping pristine graphene sheets that enables the synthesis of open cell foams containing a continuous graphitic skin network. At the heart of our technique is the strong attraction of graphene to high-energy oil and water interfaces. This allows for the creation of stable water-in-oil emulsions with controlled droplet size and overlapping graphene sheets playing the role of surfactant by covering the droplet surface and stabilizing the interfaces with a thin graphitic skin. These emulsions are used as templates for the synthesis of the open cell foams with densities below 0.35 g/cm3 and exhibiting remarkable mechanical and electrical properties including compressive moduli up to ~ 100 MPa, compressive strengths of over 8.3 MPa, and bulk conductivities approaching 7 S/m.

  5. Tunable single-photon heat conduction in electrical circuits

    E-print Network

    P. J. Jones; J. A. M. Huhtamäki; M. Partanen; K. Y. Tan; M. Möttönen

    2012-05-21

    We build on the study of single-photon heat conduction in electronic circuits taking into account the back-action of the superconductor--insulator--normal-metal thermometers. In addition, we show that placing capacitors, resistors, and superconducting quantum interference devices (SQUIDs) into a microwave cavity can severely distort the spatial current profile which, in general, should be accounted for in circuit design. The introduction of SQUIDs also allows for in situ tuning of the photonic power transfer which could be utilized in experiments on superconducting quantum bits.

  6. Conducting polymers. VI. Effect of doping with iodine on the dielectrical and electrical conduction properties of polyacrylonitrile

    NASA Astrophysics Data System (ADS)

    El-Ghamaz, N. A.; Diab, M. A.; Zoromba, M. Sh.; El-Sonbati, A. Z.; El-Shahat, O.

    2013-10-01

    The effect of doping of polyacrylonitrile (PAN) with iodine on the dielectical properties and ac conductivity as a function of temperature and frequency is investigated. Thermogravimetric analysis, TGA, and FTIR measurements show that PAN undergoes degradation starting at 523 K. Doping PAN with I2 enhances the ac electrical conductivity ?ac in the temperature range under investigation due to oligomerization of the nitrile groups giving a conjugated polyimine. The thermal activation energy, ?E, is calculated for PAN and PAN/I2 and found to be in the range 0.16-1.16 eV at 0.1 kHz. The correlated barrier hopping (CBH) conduction mechanism is found to be the dominant conduction mechanism for PAN and PAN/I2 samples.

  7. Assessing the temporal stability of spatial patterns of soil apparent electrical conductivity using geophysical methods

    NASA Astrophysics Data System (ADS)

    De Caires, Sunshine A.; Wuddivira, Mark N.; Bekele, Isaac

    2014-10-01

    Cocoa remains in the same field for decades, resulting in plantations dominated with aging trees growing on variable and depleted soils. We determined the spatio-temporal variability of key soil properties in a (5.81 ha) field from the International Cocoa Genebank, Trinidad using geophysical methods. Multi-year (2008-2009) measurements of apparent electrical conductivity at 0-0.75 m (shallow) and 0.75-1.5 m (deep) were conducted. Apparent electrical conductivity at deep and shallow gave the strongest linear correlation with clay-silt content (R = 0.67 and R = 0.78, respectively) and soil solution electrical conductivity (R = 0.76 and R = 0.60, respectively). Spearman rank correlation coefficients ranged between 0.89-0.97 and 0.81- 0.95 for apparent electrical conductivity at deep and shallow, respectively, signifying a strong linear dependence between measurement days. Thus, in the humid tropics, cocoa fields with thick organic litter layer and relatively dense understory cover, experience minimal fluctuations in transient properties of soil water and temperature at the topsoil resulting in similarly stable apparent electrical conductivity at shallow and deep. Therefore, apparent electrical conductivity at shallow, which covers the depth where cocoa feeder roots concentrate, can be used as a fertility indicator and to develop soil zones for efficient application of inputs and management of cocoa fields.

  8. An emulsion polymerization process for soluble and electrically conductive polyaniline

    SciTech Connect

    Kinlen, P.J.; Ding, Y.; Graham, C.R.; Liu, J.; Remsen, E.E.

    1998-07-01

    A new emulsion process has been developed for the direct synthesis of the emeraldine salt of polyaniline (PANI) that is soluble in organic solvents. The process entails forming an emulsion composed of water, a water soluble organic solvent (e.g., 2-butoxyethanol), a water insoluble organic acid (e.g., dinonylnaphthalene sulfonic acid) and aniline. Aniline is protonated by the organic acid to form a salt which partitions into the organic phase. As oxidant (ammonium peroxydisulfate) is added, PANI salt forms in the organic phase and remains soluble. As the reaction proceeds, the reaction mixture changes from an emulsion to a two phase system, the soluble PANI remaining in the organic phase. With dinonylnaphthalene sulfonic acid (DNNSA) as the organic acid, the resulting product is truly soluble in organic solvents such as xylene and toluene (not a dispersion), of high molecular weight (M{sub w} > 22,000), film forming and miscible with many polymers such as polyurethanes, epoxies and phenoxy resins. As cast, the polyaniline film is only moderately conductive, (10{sup {minus}5} S/cm), however treatment of the film with surfactants such as benzyltriethylammonium chloride (BTEAC) or low molecular weight alcohols and ketones such as methanol and acetone increases the conductivity 2--3 orders of magnitude.

  9. Estimation of electric conductivity of the quark gluon plasma via asymmetric heavy-ion collisions

    E-print Network

    Yuji Hirono; Masaru Hongo; Tetsufumi Hirano

    2014-12-08

    We show that in asymmetric heavy-ion collisions, especially off-central Cu+Au collisions, a sizable strength of electric field directed from Au nucleus to Cu nucleus is generated in the overlapping region, because of the difference in the number of electric charges between the two nuclei. This electric field would induce an electric current in the matter created after the collision, which result in a dipole deformation of the charge distribution. The directed flow parameters $v_1^{\\pm}$ of charged particles turn out to be sensitive to the charge dipole and provide us with information about electric conductivity of the quark gluon plasma.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  11. Modelling the electrical conductivity of iron-rich minerals for planetary applications

    NASA Astrophysics Data System (ADS)

    Vacher, P.; Verhoeven, O.

    2007-03-01

    In the framework of in situ exploration of planetary interiors, electromagnetic survey is one of the geophysical methods constraining the structure and composition of the mantle. One of the main parameters which governs the internal structure is the bulk iron content of the mantle. Unfortunately, the effect of iron on the electrical conductivity of mantle minerals is only known through a few high-pressure and high-temperature experiments. Reliable measurements on samples with different iron contents were reported for olivine, pyroxene, magnesiowüstite and perovskite/magnesiowüstite assemblage. In a first part, we parameterize the effect of iron on the electrical conductivity of these minerals. In a second part, we propose assumptions to extend this formulation to all minerals considered by the review of Xu et al. [2000b. Laboratory-based electrical conductivity in the Earth's mantle. J. Geophys. Res. 105, 27865-27875], in order to extrapolate the conductivity of terrestrial samples (i.e. with iron fraction close to 10%) to the conductivity of iron-rich minerals (up to 40%). In a third part, we apply this formulation to the computation of a synthetic electrical conductivity profile of the Martian mantle. The computed conductivity profile is 1-1.5 order of magnitude higher than terrestrial profiles, because of the higher iron content of the Martian mantle. This result highlights the possible application of electrical conductivity for constraining the composition of planetary mantles.

  12. A four-layer model for interpreting electrical conductivity measurements of clay soils near agricultural lagoons 

    E-print Network

    Jones, John Richard

    1994-01-01

    Three models were evaluated to determine their ability to predict pore water quality in the subsurface. The models interpret measurements of soil electrical conductivity taken with an electromagnetic meter. Three sites ...

  13. MAGNETIC RESONANCE ELECTRICAL IMPEDANCE TOMOGRAPHY (MR-EIT): A new technique for high resolution conductivity imaging

    E-print Network

    Eyüboðlu, Murat

    field measurements are performed by using magnetic resonance imaging techniques. The conductivity resonance imaging (MRI) techniques, if the conductor contains magnetic resonance active nuclei [2MAGNETIC RESONANCE ELECTRICAL IMPEDANCE TOMOGRAPHY (MR-EIT): A new technique for high resolution

  14. Enhanced Thermoelectric Efficiency via Orthogonal Electrical and Thermal Conductances in Phosphorene

    E-print Network

    Fei, Ruixiang; Soklaski, Ryan; Yan, Jia-An; Lo, Cynthia; Yang, Li

    2014-01-01

    Thermoelectric devices that utilize the Seebeck effect convert heat flow into electrical energy and are highly desirable for the development of portable, solid state, passively-powered electronic systems. The conversion efficiencies of such devices are quantified by the dimensionless thermoelectric figure of merit (ZT), which is proportional to the ratio of a device's electrical conductance to its thermal conductance. High ZT (>2) has been achieved in materials via all-scale hierarchical architecturing. This efficiency holds at high temperatures (700K~900K) but quickly diminishes at lower temperatures. In this paper, a recently-fabricated two-dimensional (2D) semiconductor called phosphorene (monolayer black phosphorus) is assessed for its thermoelectric capabilities. First-principles and model calculations reveal that phosphorene possesses spatially-anisotropic electrical and thermal conductances. The prominent electrical and thermal conducting directions are orthogonal to one another, enhancing the ratio of...

  15. EVIDENCE FOR MICROBIAL ENHANCED ELECTRICAL CONDUCTIVITY IN HYDROCARBON-CONTAMINATED SEDIMENTS

    EPA Science Inventory

    Electrical conductivity of sediments during microbial mineralization of diesel was investigated in a mesoscale column experiment consisting of biotic contaminated and uncontaminated columns. Microbial population numbers increased with a clear pattern of depth zonation within the ...

  16. Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

    E-print Network

    Zheng, Ruiting

    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 ...

  17. Ignition Sensitivity and Electrical Conductivity of a Composite Energetic Material with Conductive Nanofillers

    SciTech Connect

    Eric S. Collins; Brandon R. Skelton; Michelle L. Pantoya; Fahmida Irin; Micah J. Green; Michael A. Daniels

    2014-12-01

    The safe handling of powdered composite energetic materials requires an understanding of their response to electrostatic ignition stimuli. A binary composite comprised of Al and polytetrafluoroethylene (PTFE) was tailored for ESD ignition sensitivity with varied concentrations of highly conductive nanofillers. The goal was to control the ESD ignition response of the Al+PTFE with small concentrations of nanofillers that may not significantly affect the overall combustion performance of the mixture. The nanofillers examined include carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs). Adding CNTs created percolation at a lower volumetric percentage than GNPs and were found to be the controlling nanofiller, creating percolation for the mixture containing both CNTs and GNPs. Various mixing methods were examined. Ignition was achieved only for adding nanofillers at a volumetric percentage and mixing method that led to a bulk conductivity of approximately 5x10-3 ?S/cm.

  18. High frequency electrical conduction block of the pudendal nerve

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

    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.

  19. Dissociation of fullerenol-70-d in aqueous solutions and their electric conductivity

    NASA Astrophysics Data System (ADS)

    Tyurin, D. P.; Semenov, K. N.; Charykov, N. A.; Cherepkova, I. A.; Keskinov, V. A.

    2015-05-01

    The concentration dependences of specific and molar electric conductivities and the hydrogen ion exponents of aqueous solutions of fullerenol-70-d obtained via the direct heterogenic catalytic oxidation of C70 with an alkali are studied. The concentration dependences of the apparent degree of dissociation and concentration dissociation constant of fullerenol-70-d in aqueous solutions are calculated using data on the electric conductivity and hydrogen ion exponent.

  20. Electrical conductivity and equation of state measurements on planetary fluids at high pressures and temperatures

    SciTech Connect

    Hamilton, D.C.; Nellis, W.J.; Holmes, N.C.; Radousky, H.B.; Ree, F.H.; Nicol, M.

    1987-07-01

    Hugoniot equation-of-state, shock temperature, and electrical conductivity measurements are reported for fluids believed to be the primary constituents of the planets Uranus and Neptune. The equation-of-state results are compared with calculations performed using a statistical mechanical, chemical equilibrium computer code and electrical conductivities are discussed in terms of the recently measured magnetic field of Uranus. 4 refs., 2 figs., 1 tab.

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

    DOEpatents

    Tran, Nang T. (Cottage Grove, MN); Gilbert, James R. (Maplewood, MN)

    1992-08-04

    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.degree. C. to 300.degree. C. Sputtering occurs in a gaseous mixture including a sputtering gas and the stabilizing gas.

  2. IMAGING OF ELECTRODE MOVEMENT AND CONDUCTIVITY CHANGE IN ELECTRICAL IMPEDANCE TOMOGRAPHY

    E-print Network

    Adler, Andy

    IMAGING OF ELECTRODE MOVEMENT AND CONDUCTIVITY CHANGE IN ELECTRICAL IMPEDANCE TOMOGRAPHY Camille G-mail: adler@site.uottawa.ca Abstract Electrical Impedance Tomography (EIT) applies and measures elec- trical energy on the boundary of a medium to produce an image of its internal impedance distribution. In many

  3. Electrical impedance spectroscopy for electro-mechanical characterization of conductive fabrics.

    PubMed

    Bera, Tushar Kanti; Mohamadou, Youssoufa; Lee, Kyounghun; Wi, Hun; Oh, Tong In; Woo, Eung Je; Soleimani, Manuchehr; Seo, Jin Keun

    2014-01-01

    When we use a conductive fabric as a pressure sensor, it is necessary to quantitatively understand its electromechanical property related with the applied pressure. We investigated electromechanical properties of three different conductive fabrics using the electrical impedance spectroscopy (EIS). We found that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures. When we apply a mechanical tension or compression, there occur structural deformations in the conductive fabrics altering their apparent electrical impedance spectra. For a stretchable conductive fabric, the impedance magnitude increased or decreased under tension or compression, respectively. For an almost non-stretchable conductive fabric, both tension and compression resulted in decreased impedance values since the applied tension failed to elongate the fabric. To measure both tension and compression separately, it is desirable to use a stretchable conductive fabric. For any conductive fabric chosen as a pressure-sensing material, its resistivity under no loading conditions must be carefully chosen since it determines a measurable range of the impedance values subject to different amounts of loadings. We suggest the EIS method to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor. PMID:24892493

  4. Electrical Impedance Spectroscopy for Electro-Mechanical Characterization of Conductive Fabrics

    PubMed Central

    Bera, Tushar Kanti; Mohamadou, Youssoufa; Lee, Kyounghun; Wi, Hun; Oh, Tong In; Woo, Eung Je; Soleimani, Manuchehr; Seo, Jin Keun

    2014-01-01

    When we use a conductive fabric as a pressure sensor, it is necessary to quantitatively understand its electromechanical property related with the applied pressure. We investigated electromechanical properties of three different conductive fabrics using the electrical impedance spectroscopy (EIS). We found that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures. When we apply a mechanical tension or compression, there occur structural deformations in the conductive fabrics altering their apparent electrical impedance spectra. For a stretchable conductive fabric, the impedance magnitude increased or decreased under tension or compression, respectively. For an almost non-stretchable conductive fabric, both tension and compression resulted in decreased impedance values since the applied tension failed to elongate the fabric. To measure both tension and compression separately, it is desirable to use a stretchable conductive fabric. For any conductive fabric chosen as a pressure-sensing material, its resistivity under no loading conditions must be carefully chosen since it determines a measurable range of the impedance values subject to different amounts of loadings. We suggest the EIS method to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor. PMID:24892493

  5. Sensing the water content of honey from temperature-dependent electrical conductivity

    NASA Astrophysics Data System (ADS)

    Guo, Wenchuan; Liu, Yi; Zhu, Xinhua; Zhuang, Hong

    2011-08-01

    In order to predict the water content in honey, electrical conductivity was measured on blossom honey types milk-vetch, jujube and yellow-locust with the water content of 18-37% between 5 and 40 °C. The regression models of electrical conductivity were developed as functions of water content and temperature. The results showed that increases in either water content or temperature resulted in an increase in the electrical conductivity of honey with greater changes at higher water content and/or higher temperature. The linear terms of water content and temperature, a quadratic term of water content, and the interaction effect of water content and temperature had significant influence on the electrical conductivity of honey (p < 0.0001). Regardless of blossom honey type, the linear coefficient of the determination of measured and calculated electrical conductivities was 0.998 and the range error ratio was larger than 100. These results suggest that the electrical conductivity of honey might be used to develop a detector for rapidly predicting the water content in blossom honey.

  6. Noninvasive Imaging of Head-Brain Conductivity Profiles Using Magnetic Resonance Electrical Impedance Imaging

    PubMed Central

    Zhang, Xiaotong; Yan, Dandan; Zhu, Shanan; He, Bin

    2008-01-01

    Magnetic resonance electrical impedance tomography (MREIT) is a recently introduced non-invasive conductivity imaging modality, which combines the magnetic resonance current density imaging (CDI) and the traditional electrical impedance tomography (EIT) techniques. MREIT is aimed at providing high spatial resolution images of electrical conductivity, by avoiding solving the well-known ill-posed problem in the traditional EIT. In this paper, we review our research activities in MREIT imaging of head-brain tissue conductivity profiles. We have developed several imaging algorithms and conducted a series of computer simulations for MREIT imaging of the head and brain tissues. Our work suggests MREIT brain imaging may become a useful tool in imaging conductivity distributions of the brain and head. PMID:18799394

  7. Electrical Conductivity Response of Poly(Phenylene-vinylene)/Zeolite Composites Exposed to Ammonium Nitrate

    PubMed Central

    Kamonsawas, Jirarat; Sirivat, Anuvat; Niamlang, Sumonman; Hormnirun, Pimpa; Prissanaroon-Ouajai, Walaiporn

    2010-01-01

    Poly(p-phenylenevinylene) (PPV) was chemically synthesized via the polymerization of p-xylene-bis(tetrahydrothiophenium chloride) monomer and doped with H2SO4. To improve the electrical conductivity sensitivity of the conductive polymer, Zeolites Y (Si/Al = 5.1, 30, 60, 80) were added into the conductive polymer matrix. All composite samples show definite positive responses towards NH4NO3. The electrical conductivity sensitivities of the composite sensors increase linearly with increasing Si/Al ratio: with values of 0.201, 1.37, 2.80 and 3.18, respectively. The interactions between NH4NO3 molecules and the PPV/zeolite composites with respect to the electrical conductivity sensitivity were investigated through the infrared spectroscopy. PMID:22219677

  8. Electrical measurements in the atmosphere and the Ionosphere over an active thunderstorm. II - Direct current electric fields and conductivity

    NASA Technical Reports Server (NTRS)

    Holzworth, R. H.; Kelley, M. C.; Siefring, C. L.; Hale, L. C.; Mitchell, J. D.

    1985-01-01

    On August 9, 1981, a series of three rockets was launched over an air mass thunderstorm off the eastern seaboard of Virginia while simultaneous stratospheric and ground-based electric field measurements were made. The conductivity was substantially lower at most altitudes than the conductivity profiles used by theoretical models. Direct current electric fields over 80 mV/m were measured as far away as 96 km from the storm in the stratosphere at 23 km altitude. No dc electric fields above 75 km altitude could be identified with the thunderstorm, in agreement with theory. However, vertical current densities over 120 pA/sq m were seen well above the classical 'electrosphere' (at 50 or 60 km). Frequent dc shifts in the electric field following lightning transients were seen by both balloon and rocket payloads. These dc shifts are clearly identifiable with either cloud-to-ground (increases) or intercloud (decreases) lightning flashes.

  9. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

    2015-12-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

  10. Electrical stimulation on biodegradation of phenol and responses of microbial communities in conductive carriers supported biofilms of the bioelectrochemical reactor.

    PubMed

    Ailijiang, Nuerla; Chang, Jiali; Liang, Peng; Li, Peng; Wu, Qing; Zhang, Xiaoyuan; Huang, Xia

    2016-02-01

    Conductive carbon felts (Cf) were used as biofilm carriers in bioelectrochemical reactors to enhance the electrical stimulation on treatment of phenol-containing synthetic wastewater. In batch test, phenol biodegradation was accelerated under an optimum direct current (DC), which was 2mA for Cf biofilm carriers, lower than that for non-conductive white foam carriers. The stimulation effect was consistent with Adenosine Triphosphate contents in biofilms. The long-term operation further demonstrated that a high and stable phenol removal efficiency could be achieved with applied DC of 2mA, and intermittent DC application was better than continuous one, with phenol removal efficiency of over 97%. Although the quantities of whole microbial communities kept at a high level under all conditions, special microorganisms related with genera of Zoogloea and Desulfovibrio were distinctively enriched under intermittent applied DC pattern. This study shows that the electrical stimulation is potentially effective for biofilm reactors treating phenol-containing wastewater. PMID:26615496

  11. Resistive switching memory devices based on electrical conductance tuning in poly(4-vinyl phenol)-oxadiazole composites.

    PubMed

    Sun, Yanmei; Miao, Fengjuan; Li, Rui; Wen, Dianzhong

    2015-11-28

    Nonvolatile memory devices, based on electrical conductance tuning in thin films of poly(4-vinyl phenol) (PVP) and 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) composites, are fabricated. The current-voltage characteristics of the fabricated devices show different electrical conductance behaviors, such as the write-once read-many-times (WORM) memory effect, the rewritable flash memory effect and insulator behavior, which depend on the content of PBD in the PVP + PBD composites. The OFF and ON states of the WORM and rewritable flash memory devices are stable under a constant voltage stress or a continuous pulse voltage stress at a read voltage. The memory mechanism is deduced from the modeling of the nature of currents in both states in the devices. PMID:26490192

  12. Systems Characterization of Temperature, Ph and Electrical Conductivity in Aerobic Biodegradation of Wheat Biomass at Differing Mixing Rates

    NASA Technical Reports Server (NTRS)

    Calhoun, M.; Trotman, A.; Aglan, H.

    1998-01-01

    The purpose of this preliminary study is to observe and relate the rate of mixing to pH and electrical conductivity in an aerobic, continuously stirred bioreactor. The objective is to use data collected from successive experiments as a means of a system characterization. Tests were conducted to obtain these data using a continuously stirred 20 L Cytostir glass reaction vessel as a bioreactor operated without built-in temperature or pH control. The tests were conducted on the lab bench at ambient temperatures. The substrate in the bioreactor was ground wheat biomass obtained from the Biomass Production Chamber at NASA Kennedy Space Center. In this study, the data reflect characteristics of the native (uninoculated) systems as well as inoculated systems. In the native systems, it was found that pi levels became stable after approximately 2 to 3 days. The electrical conductivity levels for the native systems tended to decrease over time. In contrast, ion activity was increased after the introduction of bacteria into the system. This could be correlated with the release of nutrients, due to the activity of the bacteria. Also, there were slight increases in pH in the inoculated system, a result which is expected for a system with no active pr controls. The data will be used to test a mathematical model in an automated system.

  13. Ground-based instrumentation for measurements of atmospheric conduction current and electric field at the South Pole

    NASA Technical Reports Server (NTRS)

    Byrne, G. J.; Benbrook, J. R.; Bering, E. A.; Few, A. A.; Morris, G. A.; Trabucco, W. J.; Paschal, E. W.

    1993-01-01

    Attention is given to instruments constructed to measure the atmospheric conduction current and the atmospheric electric field - two fundamental parameters of the global-electric circuit. The instruments were deployed at the Amundsen-Scott South Pole Station in January 1991 and are designed to operate continuously for up to one year without operator intervention. The atmospheric current flows into one hemisphere, through the electronics where it is measured, and out the other hemisphere. The electric field is measured by a field mill of the rotating dipole type. Sample data from the first days of operation at the South Pole indicate variations in the global circuit over time scales from minutes to hours to days.

  14. Solid State Physics View of Liquid State Chemistry III. Electrical Conductance of Pure and Impure Water

    NASA Astrophysics Data System (ADS)

    Binbin, Jie; Chihtang, Sah

    2014-04-01

    The ‘abnormally’ high electrical conductivity of pure water was recently studied by us using our protonic bond, trap and energy band model, with five host particles: the positive and negative protons, and the amphoteric protonic trap in three charge states, positive, neutral and negative. Our second report described the electrical charge storage capacitance of pure and impure water. This third report presents the theory of particle density and electrical conductance of pure and impure water, including the impuritons, which consist of an impurity ion bonded to a proton, proton-hole or proton trap and which significantly affect impure waters' properties.

  15. Column displacement experiments to evaluate electrical conductivity effects on electromagnetic soil water sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bulk electrical conductivity (EC) in superactive soils has been shown to strongly influence electromagnetic sensing of permittivity. However, these effects are dependent on soil water content and temperature as well as the pore water conductivity. We carried out isothermal column displacement experi...

  16. How Well Does Zone Sampling Based On Soil Electrical Conductivity Maps Represent Soil Variability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    How Well Does Zone Sampling Based On Soil Electrical Conductivity Maps Represent Soil Variability. Dale L. Shaner A study was conducted determined if ECa-directed zone sampling could predict soil texture and soil organic matter (SOM) patterns of samples taken by a more intensive grid sample method...

  17. Thermal and electrical conductivities of water-based nanofluids prepared with long multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Glory, J.; Bonetti, M.; Helezen, M.; Mayne-L'Hermite, M.; Reynaud, C.

    2008-05-01

    Thermal and electrical conductivities of suspensions of multiwalled carbon nanotubes (MWCNT) in water were measured as a function of temperature, nanotube weight content, and nanotube length. Nanotubes were dispersed in water by using gum Arabic as surfactant. The thermal conductivity was measured by the steady-state method by using a coaxial-cylinder cell that allows the sample temperature to be varied from 15to75°C. Our measurements show that the thermal conductivity enhancement as compared to water linearly increases when the MWCNT weight content increases from 0.01to3wt%, reaching 64% for the MWCNT weight content of 3wt%. The thermal conductivity enhancement is found to be temperature independent up to MWCNT weight content of 2wt%. The average length of the nanotubes appears to be a very sensitive parameter. The thermal conductivity enhancement as compared to water increases by a factor of 3 when the nanotube average length increases in the 0.5-5?m range. Electrical conductivity measurements show that the electrical properties do not follow the same trend as a function of MWCNT weight content, as compared to thermal properties. The electrical conductivity is mainly constant in the studied range, but undergoes a drop when the weight content decreases to about 0.1wt%, which suggests that the MWCNT network in the base fluid might be percolating at this very low value. By comparison, the thermal conductivity does not show any percolation threshold.

  18. Electrical Conductivity Measurement through the Loaded Q Factor of a Resonant Cavity

    E-print Network

    Research, P.O. Box 515, S. J. Campos, 12201-970 SP, Brazil Abstract=We present a method for measuring. INTRODUCTION In the method presented here, the electrical conductivity measurement of metallic materials. of the conductor penetrated by the fields due to skin effect. Now if we replace the upper disk (with conductivity R

  19. Use of fathometers and electrical-conductivity probes to monitor riverbed scour at bridge piers

    USGS Publications Warehouse

    Hayes, D.C.; Drummond, F.E.

    1995-01-01

    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.

  20. Electrical conductivity of strongly degenerate plasma with the account of electron-electron scattering

    NASA Astrophysics Data System (ADS)

    Karakhtanov, V. S.

    2014-08-01

    The influence of electron-electron scattering on the strongly degenerate plasma conductivity is investigated with a linear response theory. In the present work the temperature dependence of the electron-electron scattering term of the electrical conductivity and further modification of the Ziman formula are discussed.

  1. Preparation and properties of electrically conducting ceramics based on indium oxide-rare Earth oxides-hafnium oxide

    SciTech Connect

    Marchant, D.D.; Bates, J.L.

    1983-10-01

    Electrically conducting refractory oxides based on adding indium oxide to rare earth-stabilized hafnium oxide are being studied. The use of indium oxide generally increases the electrical conductivity. The results of measurements of the electrical conductivity and data on corrosion resistance in molten salts are presented.

  2. Study on a Haptic Sensor Using MCF (Magnetic Compound Fluid) Electric Conductive Rubber

    NASA Astrophysics Data System (ADS)

    Zheng, Yaoyang; Shimada, Kunio

    To provide a new composite material having a high degree of sensitivity regarding both electrical conduction and temperature for the field of robotics or sensing, we have developed magnetic rubber that contains a network-like magnetic cluster. We compared the temperature response of MCF rubber with others rubbers made under various experimental conditions, allowing us to find an optimum condition for making MCF rubber. The temperature response was obtained by an experimental equation. We also compared the electric conductivity of MCF rubber with that of ordinary electric conductive rubber and found that its electric sensitivity was lower at a small deformation, but increased at larger deformations. Therefore, MCF rubber has proven itself effective as a switching sensor when a small deformation is applied.

  3. High electrical conductivity in out of plane direction of electrodeposited Bi2Te3 films

    NASA Astrophysics Data System (ADS)

    Rojo, Miguel Muñoz; Manzano, Cristina V.; Granados, Daniel; Osorio, M. R.; Borca-Tasciuc, Theodorian; Martín-González, Marisol

    2015-08-01

    The out of plane electrical conductivity of highly anisotropic Bi2Te3 films grown via electro-deposition process was determined using four probe current-voltage measurements performed on 4.6 - 7.2 ?m thickness Bi2Te3 mesa structures with 80 - 120 ?m diameters sandwiched between metallic film electrodes. A three-dimensional finite element model was used to predict the electric field distribution in the measured structures and take into account the non-uniform distribution of the current in the electrodes in the vicinity of the probes. The finite-element modeling shows that significant errors could arise in the measured film electrical conductivity if simpler one-dimensional models are employed. A high electrical conductivity of (3.2 ± 0.4) ? 105 S/m is reported along the out of plane direction for Bi2Te3 films highly oriented in the [1 1 0] direction.

  4. Electrical conductivity of lawsonite and dehydrating fluids at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Manthilake, Geeth; Mookherjee, Mainak; Bolfan-Casanova, Nathalie; Andrault, Denis

    2015-09-01

    Lawsonite is a calcium-aluminum bearing hydrous silicate mineral with CaAl2Si2O7(OH)2.H2O stoichiometry. It is thermodynamically stable in the hydrated oceanic crust. Low-velocity anomalies observed in the cold subducted slabs have been related to the unusual shear wave velocities of lawsonite eclogite. However, electrical conductivity of lawsonite at high pressure and temperature remains unknown. In this study, we measured the electrical conductivity of lawsonite at 7 GPa, and temperatures ranging from 298 K-1320 K. At 1173 K, the electrical conductivity of lawsonite is around 10-1 S/m. A sharp increase of electrical conductivity is observed at temperatures exceeding the dehydration ~1258 K. The high electrical conductivity up to 101 S/m observed in our experiments is due to the presence of highly conductive fluid and could explain the low resistivity observed at 150-250 km depths in subduction zone settings such as NE Japan, northern, and central Chile.

  5. Electrical conductivity of the quark-gluon plasma across the deconfinement transition

    E-print Network

    Alessandro Amato; Gert Aarts; Chris Allton; Pietro Giudice; Simon Hands; Jon-Ivar Skullerud

    2013-10-21

    A lattice calculation is presented for the electrical conductivity of the QCD plasma with 2+1 dynamical flavours at nonzero temperature. We employ the conserved lattice current on anisotropic lattices using a tadpole-improved clover action and study the behaviour of the conductivity over a wide range of temperatures, both below and above the deconfining transition. The conductivity is extracted from a spectral-function analysis using the Maximal Entropy Method and a discussion of its systematics is provided.

  6. 75 FR 63166 - South Carolina Electric & Gas Company; Notice of Authorization for Continued Project Operation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-14

    ... Energy Regulatory Commission South Carolina Electric & Gas Company; Notice of Authorization for Continued Project Operation October 6, 2010. On August 28, 2008 South Carolina Electric & Gas Company, licensee for the Saluda Hydroelectric Project, filed an Application for a New License pursuant to the Federal...

  7. 78 FR 29365 - Pacific Gas and Electric Company; Notice of Authorization for Continued Project Operation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-20

    ... Energy Regulatory Commission Pacific Gas and Electric Company; Notice of Authorization for Continued Project Operation On April 12, 2011, the Pacific Gas and Electric Company, licensee for the Drum-Spaulding Hydroelectric Project, filed an Application for a New License pursuant to the Federal Power Act (FPA) and...

  8. Towards practical application of paper based printed circuits: capillarity effectively enhances conductivity of the thermoplastic electrically conductive adhesives.

    PubMed

    Wu, Haoyi; Chiang, Sum Wai; Lin, Wei; Yang, Cheng; Li, Zhuo; Liu, Jingping; Cui, Xiaoya; Kang, Feiyu; Wong, Ching Ping

    2014-01-01

    Direct printing nanoparticle-based conductive inks onto paper substrates has encountered difficulties e.g. the nanoparticles are prone to penetrate into the pores of the paper and become partially segmented, and the necessary low-temperature-sintering process is harmful to the dimension-stability of paper. Here we prototyped the paper-based circuit substrate in combination with printed thermoplastic electrically conductive adhesives (ECA), which takes the advantage of the capillarity of paper and thus both the conductivity and mechanical robustness of the printed circuits were drastically improved without sintering process. For instance, the electrical resistivity of the ECA specimen on a pulp paper (6 × 10(-5)? · cm, with 50 wt% loading of Ag) was only 14% of that on PET film than that on PET film. This improvement has been found directly related to the sizing degree of paper, in agreement with the effective medium approximation simulation results in this work. The thermoplastic nature also enables excellent mechanical strength of the printed ECA to resist repeated folding. Considering the generality of the process and the wide acceptance of ECA technique in the modern electronic packages, this method may find vast applications in e.g. circuit boards, capacitive touch pads, and radio frequency identification antennas, which have been prototyped in the manuscript. PMID:25182052

  9. Towards Practical Application of Paper based Printed Circuits: Capillarity Effectively Enhances Conductivity of the Thermoplastic Electrically Conductive Adhesives

    PubMed Central

    Wu, Haoyi; Chiang, Sum Wai; Lin, Wei; Yang, Cheng; Li, Zhuo; Liu, Jingping; Cui, Xiaoya; Kang, Feiyu; Wong, Ching Ping

    2014-01-01

    Direct printing nanoparticle-based conductive inks onto paper substrates has encountered difficulties e.g. the nanoparticles are prone to penetrate into the pores of the paper and become partially segmented, and the necessary low-temperature-sintering process is harmful to the dimension-stability of paper. Here we prototyped the paper-based circuit substrate in combination with printed thermoplastic electrically conductive adhesives (ECA), which takes the advantage of the capillarity of paper and thus both the conductivity and mechanical robustness of the printed circuitsweredrastically improved without sintering process. For instance, the electrical resistivity of the ECA specimen on a pulp paper (6 × 10?5?·cm, with 50?wt% loading of Ag) was only 14% of that on PET film than that on PET film. This improvement has been found directly related to the sizing degree of paper, in agreement with the effective medium approximation simulation results in this work. The thermoplastic nature also enables excellent mechanical strength of the printed ECA to resist repeated folding. Considering the generality of the process and the wide acceptance of ECA technique in the modern electronic packages, this method may find vast applications in e.g. circuit boards, capacitive touch pads, and radio frequency identification antennas, which have been prototyped in the manuscript. PMID:25182052

  10. Investigation of electrical conductivity and equations of state of non-ideal plasma through underwater electrical wire explosion

    SciTech Connect

    Sheftman, D.; Krasik, Ya. E.

    2010-11-15

    The results of experiments and magnetohydrodynamic simulations of nanosecond time scale underwater electrical explosions of Al, Cu, and W wires are presented. Experiments were performed using a nanosecond pulsed generator with a {approx}30 kA amplitude and {approx}60 ns rise time current pulse. The electrical conductivity of the tested materials in the density and temperature ranges of 0.1-20 g/cm{sup 3} and 0.03-8 eV, respectively, is presented. It is shown that for the physical conditions obtained in these experiments, the equation of state data used in the SESAME tables must be modified in order to reproduce the experimental results. Also, it was shown that the electrical conductivity of the metals does not consistently fit over the entire range of experimental conditions with either of the transport models presented.

  11. Temperature dependence of dc electrical conductivity of activated carbon-metal oxide nanocomposites. Some insight into conduction mechanisms

    NASA Astrophysics Data System (ADS)

    Barroso-Bogeat, Adrián; Alexandre-Franco, María; Fernández-González, Carmen; Sánchez-González, José; Gómez-Serrano, Vicente

    2015-12-01

    From a commercial activated carbon (AC) and six metal oxide (Al2O3, Fe2O3, SnO2, TiO2, WO3 and ZnO) precursors, two series of AC-metal oxide nanocomposites are prepared by wet impregnation, oven-drying at 120 °C, and subsequent heat treatment at 200 or 850 °C in inert atmosphere. The temperature-dependent dc electrical conductivity of AC and the as-prepared nanocomposites is measured from room temperature up to ca. 200 °C in air atmosphere by the four-probe method. The decrease in conductivity for the hybrid materials as compared to AC is the result of a complex interplay between several factors, including not only the intrinsic conductivity, crystallite size, content and chemical nature of the supported nanoparticles, which ultimately depend on the precursor and heat treatment temperature, but also the adsorption of oxygen and water from the surrounding atmosphere. The conductivity data are discussed in terms of a thermally activated process. In this regard, both AC and the prepared nanocomposites behave as semiconductors, and the temperature-dependent conductivity data have been interpreted on the basis of the classical model proposed by Mott and Davis. Because of its high content of heteroatoms, AC may be considered as a heavily doped semiconductor, so that conduction of thermally excited carriers via acceptor or donor levels is expected to be the dominant mechanism. The activation energies for the hybrid materials suggest that the supported metal oxide nanoparticles strongly modify the electronic band structure of AC by introducing new trap levels in different positions along its band gap. Furthermore, the thermally activated conduction process satisfies the Meyer-Neldel rule, which is likely connected with the shift of the Fermi level due to the introduction of the different metal oxide nanoparticles in the AC matrix.

  12. A chemically polymerized electrically conducting composite of polypyrrole nanoparticles and polyurethane for tissue engineering.

    PubMed

    Broda, Christopher R; Lee, Jae Y; Sirivisoot, Sirinrath; Schmidt, Christine E; Harrison, Benjamin S

    2011-09-15

    A variety of cell types respond to electrical stimuli; accordingly, many conducting polymers (CPs) have been used as tissue engineering (TE) scaffolds, and one such CP is polypyrrole (PPy). PPy is a well-studied biomaterial with potential TE applications because of its electrical conductivity and many other beneficial properties. Combining its characteristics with an elastomeric material, such as polyurethane (PU), may yield a hybrid scaffold with electrical activity and significant mechanical resilience. Pyrrole was in situ polymerized within a PU emulsion mixture in weight ratios of 1:100, 1:20, 1:10, and 1:5, respectively. Morphology, electrical conductivity, mechanical properties, and cytocompatibility with C2C12 myoblast cells were characterized. The polymerization resulted in a composite with a principle base of PU interspersed with an electrically percolating network of PPy nanoparticles. As the mass ratio of PPy to PU increased so did electrical conductivity of the composites. In addition, as the mass ratio of PPy to PU increased, stiffness of the composite increased while maximum elongation length decreased. Ultimate tensile strength was reduced by ~47% across all samples with the addition of PPy to the PU base. Cytocompatibility assay data indicated no significant cytotoxic effect from the composites. Static cellular seeding of C2C12 cells and subsequent differentiation showed myotube formation on the composite materials. PMID:21681943

  13. A Chemically Polymerized Electrically Conducting Composite of Polypyrrole Nanoparticles and Polyurethane for Tissue Engineering

    PubMed Central

    Broda, Christopher R.; Lee, Jae Y.; Sirivisoot, Sirinrath; Schmidt, Christine E.; Harrison, Benjamin S.

    2011-01-01

    A variety of cell types respond to electrical stimuli, accordingly many conducting polymers (CPs) have been used as tissue engineering (TE) scaffolds, one such CP is polypyrrole (PPy). PPy is a well studied biomaterial with potential TE applications due to its electrical conductivity and many other beneficial properties. Combining its characteristics with an elastomeric material, such as polyurethane (PU), may yield a hybrid scaffold with electrical activity and significant mechanical resilience. Pyrrole was in situ polymerized within a PU emulsion mixture in weight ratios of 1:100, 1:20, 1:10 and 1:5, respectively. Morphology, electrical conductivity, mechanical properties and cytocompatibility with C2C12 myoblast cells were characterized. The polymerization resulted in a composite with a principle base of PU interspersed with an electrically percolating network of PPy nanoparticles. As the mass ratio of PPy to PU increased so did electrical conductivity of the composites. In addition, as the mass ratio of PPy to PU increased, stiffness of the composite increased while maximum elongation length decreased. Ultimate tensile strength was reduced by approximately 47% across all samples with the addition of PPy to the PU base. Cytocompatibility assay data indicated no significant cytotoxic effect from the composites. Static cellular seeding of C2C12 cells and subsequent differentiation showed myotube formation on the composite materials. PMID:21681943

  14. Laboratory and Field Measurements of Soil Bulk Electrical Conductivity Using Time Domain Reflectometry

    NASA Astrophysics Data System (ADS)

    Hsu, S.; Chiu, Y.

    2013-12-01

    As the increasing of contamination in soil and groundwater, there is a demand for fast, accurate, and cost-effective techniques for contaminated site investigation. Time domain reflectometry (TDR) is a nondestructive geophysical method that allows, in real time, simultaneous estimation of both the dielectric constant and the bulk soil electrical conductivity (EC). On such bases, TDR is a technique that could potentially be adapted for continuous monitoring of solute contaminants in soil and water. The objective of this study is to assess the performance of TDR for estimating the EC and the solute concentration through the laboratory experiments and then applied it to a field of mercury contamination in the sediments. Measurement of EC using TDR is based on the attenuation of the applied voltage as it traverses the medium of interest. Once the geometric constant of the probe can be determined and the mismatch of the TDR instrument can be corrected during the experimental setup, EC can easily be accurately evaluated through a single TDR measurement on the considered sample. The results obtained from the laboratory experiments showed the good agreement between the TDR measurement and conductivity meter, and the linear relationship between EC and solute concentration is also validated. Given a specific concentration of solution, the decrease of EC with the decrease of water content followed Archie's law. Experiments with releasing a pulse and continuous potassium nitrate solutions into a soil column were conducted to demonstrate the TDR capability of real time monitoring. The results showed that the breakthrough curve (BC) can be accurately and clearly delineated by the TDR measurement. In this study, the TDR application was also extended to a contaminated site in southern Taiwan. The mercury contaminated sediments were deposited at the bottom of saline lakes and the TDR probes were modified to overcome the measurement under the water. The field work showed that the spatial distribution of relative-high mercury concentrations could be identified by TDR. Although the absolute mercury concentration is still undetermined, but the feasibility of using TDR as a reference tool for contaminant site investigation and self-assessment of remediation was successfully demonstrated.

  15. The Electrical and Thermal Conductivity of Woven Pristine and Intercalated Graphite Fiber-Polymer Composites

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Vandenburg, Yvonne Yoder; Berkebile, Steven; Stueben, Heather; Balagadde, Frederick

    2002-01-01

    A series of woven fabric laminar composite plates and narrow strips were fabricated from a variety of pitch-based pristine and bromine intercalated graphite fibers in an attempt to determine the influence of the weave on the electrical and thermal conduction. It was found generally that these materials can be treated as if they are homogeneous plates. The rule of mixtures describes the resistivity of the composite fairly well if it is realized that only the component of the fibers normal to the equipotential surface will conduct current. When the composite is narrow with respect to the fiber weave, however, there is a marked angular dependence of the resistance which was well modeled by assuming that the current follows only along the fibers (and not across them in a transverse direction), and that the contact resistance among the fibers in the composite is negligible. The thermal conductivity of composites made from less conductive fibers more closely followed the rule of mixtures than that of the high conductivity fibers, though this is thought to be an artifact of the measurement technique. Electrical and thermal anisotropy could be induced in a particular region of the structure by weaving together high and low conductivity fibers in different directions, though this must be done throughout all of the layers of the structure as interlaminar conduction precludes having only the top layer carry the anisotropy. The anisotropy in the thermal conductivity is considerably less than either that predicted by the rule of mixtures or the electrical resistivity.

  16. Electrical conductivity of fluid-bearing quartzite at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Shimojuku, A.; Yoshino, T.; Yamazaki, D.

    2010-12-01

    It has been reported that the electrical conductivities determined by magnetotelluric methods are much higher than those determined by dry laboratory sample of crustal rocks (e.g., Shankland and Ander, 1983). The possible reasons of the high-conductivity anomaly regions are interconnected graphite films, partial melt, and aqueous fluid (e.g., Glover and Vine, 1994). Because the solubility of silicate component in the aqueous fluid should increase with increasing pressure, the electrical conductivity of fluid-bearing rocks can be higher at pressure of the lower crust even if there is no brine. To clarify the effect of the soluble ionic species in aqueous fluid on the bulk rock conductivity, we measured the electrical conductivity of fluid-bearing quartzite as functions of temperature and fluid content at high pressure. Based on the result, we discuss the fluid content in the crust. High-pressure experiments were conducted using a DIA-type high-pressure apparatus. Pressure medium is pyrophyllite and heater is graphite. The starting materials were mixture of quartz powder plus silicic acid, or quartz aggregate synthesized using Piston-cylinder apparatus plus silicic acid. Electrical conductivity was determined by impedance spectroscopy method. To prevent a loss of water during the electrical conductivity measurements, we used a diamond single crystal capsule. The pressure is 1 GPa, and temperature range is 700-1100K. The texture of the recovered samples was observed using field-emission scanning electron microscope, and the fluid content was measured from the obtained SEM images. The electrical conductivity of fluid-bearing quartzite (fluid fraction=0.29) is about 4 orders of magnitude higher than that of dry quartzite at 1000K. Our result suggests that the observational electrical conductivity at Tohoku, Japan (Ogawa et al. 2001) and New Zealand (Wannamaker et al. 2009) in the middle crust is unable to account for quartz plus H2O. Therefore, plausible explanations of high-conductivity anomaly are presence of saline fluid and/or the other ionic species.

  17. Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

    NASA Astrophysics Data System (ADS)

    Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

    2005-01-01

    This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed.

  18. Laboratory studies of the electrical conductivity of silicate perovskites at high pressures and temperatures

    NASA Technical Reports Server (NTRS)

    Li, Xiaoyuan; Jeanloz, Raymond

    1990-01-01

    The electrical conductivities of two silicate perovskites and a perovskite-magnesiowuestite assemblage, all having an atomic ratio of Mg to Fe equal to 0.88/0.12, have been measured with alternating current and direct current (dc) techniques at simultaneously high pressures and temperatures. Measurements up to pressures of 80 GPa and temperatures of 3500 K, using a laser-heated diamond anvil cell, demonstrate that the electrical conductivity of these materials remains below 10-3 S/m at lower mantle conditions. The activation energies for electrical conduction are between 0.1 and 0.4 eV from the data, and the conduction in these perovskites is ascribed to an extrinsic electronic process. The new measurements are in agreement with a bound that was previously obtained from dc measurements for the high-PT conductivity of perovskite-dominated assemblages. The results show that the electrical conductivity of (Mg/0.88/Fe/0.12)SiO3 perovskite differs significantly from that of the earth's deep mantle, as inferred from geophysical observations.

  19. Enhanced thermoelectric efficiency via orthogonal electrical and thermal conductances in phosphorene.

    PubMed

    Fei, Ruixiang; Faghaninia, Alireza; Soklaski, Ryan; Yan, Jia-An; Lo, Cynthia; Yang, Li

    2014-11-12

    Thermoelectric devices that utilize the Seebeck effect convert heat flow into electrical energy and are highly desirable for the development of portable, solid state, passively powered electronic systems. The conversion efficiencies of such devices are quantified by the dimensionless thermoelectric figure of merit (ZT), which is proportional to the ratio of a device's electrical conductance to its thermal conductance. In this paper, a recently fabricated two-dimensional (2D) semiconductor called phosphorene (monolayer black phosphorus) is assessed for its thermoelectric capabilities. First-principles and model calculations reveal not only that phosphorene possesses a spatially anisotropic electrical conductance, but that its lattice thermal conductance exhibits a pronounced spatial-anisotropy as well. The prominent electrical and thermal conducting directions are orthogonal to one another, enhancing the ratio of these conductances. As a result, ZT may reach the criterion for commercial deployment along the armchair direction of phosphorene at T = 500 K and is close to 1 even at room temperature given moderate doping (?2 × 10(16) m(-2) or 2 × 10(12) cm(-2)). Ultimately, phosphorene hopefully stands out as an environmentally sound thermoelectric material with unprecedented qualities. Intrinsically, it is a mechanically flexible material that converts heat energy with high efficiency at low temperatures (?300 K), one whose performance does not require any sophisticated engineering techniques. PMID:25254626

  20. Surface electrical conductivity of single crystal spinel in cesium vapor. Final report

    SciTech Connect

    Agnew, P.; Ing, J.L.

    1995-04-02

    The operation of a thermionic fuel element (TFE) requires the maintenance of good electrical resistance between the anode and cathode, and between the electrodes and the TFE body. A program of research was established as part of the TOPAZ International Program (TIP) with the purpose of investigating the degradation of TFE electrical insulators. The major emphasis of this research has been on the interactions of oxide ceramics with cesium (Cs) vapor, and the resurfacing decrease of surface resistivity. Previous work has studied the surface electrical conductivity of sapphire exposed to Cs. In this report the authors describe the results of an experimental investigation of the surface electrical conductivity of single crystal magnesium aluminate spinel at temperatures ranging from 573K to 923K, in the presence of cesium vapor at pressures up to 1 Torr. The interest in spinel has arisen in view of its apparent resistance to radiation damage.

  1. Electrical conductivity modeling and research of polypropylene composites filled with carbon black

    NASA Astrophysics Data System (ADS)

    Stepashkina, A. S.; Tsobkallo, E. S.; Alyoshin, A. N.

    2014-12-01

    Composites of polypropylene filled with carbon black (PP/CB composite) at different concentrations were prepared by melt mixing followed by compression molding. The dependence of electrical resistance on the filler mass fraction was experimentally received. It was shown that the received dependence had the threshold character. The composite kept dielectric properties at the filler concentration below the threshold and at the concentration above the threshold the electrical resistance decreased more than on 8-10 orders. The theoretical description of electrical conductivity of the composite was offered. Experimental data of the dependence between electrical resistance and the filler mass fraction agreed with the theoretical. The process of conductivity in the PP/CB composite was simulated by means of the Monte-Carlo method for threshold mass fraction estimation.

  2. Electrical Conductivity of an Anisotropic Quark Gluon Plasma : A Quasiparticle Approach

    E-print Network

    Srivastava, P K; Patra, Binoy Krishna

    2015-01-01

    The study of transport coefficients of strongly interacting matter got impetus after the discovery of perfect fluid ever created at ultrarelativistic heavy ion collision experiments. In this article, we have calculated one such coefficient viz. electrical conductivity of the quark gluon plasma (QGP) phase which exhibits a momentum anisotropy. Relativistic Boltzmann's kinetic equation has been solved in the relaxation-time approximation to obtain the electrical conductivity. We have used the quasiparticle description to define the basic properties of QGP. We have compared our model results with the corresponding results obtained in different lattice as well as other model calculations. Furthermore, we extend our model to calculate the electrical conductivity at finite chemical potential.

  3. Mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogels

    SciTech Connect

    Worsley, Marcus A; Baumann, Theodore F; Satcher, Jr., Joe H

    2014-04-01

    A method of making a mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel, including the steps of dispersing nanotubes in an aqueous media or other media to form a suspension, adding reactants and catalyst to the suspension to create a reaction mixture, curing the reaction mixture to form a wet gel, drying the wet gel to produce a dry gel, and pyrolyzing the dry gel to produce the mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel. The aerogel is mechanically robust, electrically conductive, and ultralow-density, and is made of a porous carbon material having 5 to 95% by weight carbon nanotubes and 5 to 95% carbon binder.

  4. Modeling electric conduction in composite materials based on polypropylene and carbon black

    NASA Astrophysics Data System (ADS)

    Stepashkina, A. S.; Tsobkallo, E. S.; Moskalyuk, O. A.; Aleshin, A. N.

    2015-01-01

    We have created a composite material based on polypropylene (PP) with carbon black as the filler. The dependence of the electric resistivity of the composite on the filler mass fraction has been experimentally studied. It is established that this dependence has a threshold character and the material retains dielectric properties at filler concentrations below the percolation threshold. Above the threshold, the resistivity drops by from eight to ten orders of magnitude. A theoretical description of the electric conduction of the composite is proposed, and it is shown that theoretical values of the conductivity quite satisfactorily coincide with experimental data. The process of electric conduction of the composite material has been simulated in order to determine the percolation threshold by the Monte Carlo method.

  5. Electrical Conductivity of an Anisotropic Quark Gluon Plasma : A Quasiparticle Approach

    E-print Network

    P. K. Srivastava; Lata Thakur; Binoy Krishna Patra

    2015-01-15

    The study of transport coefficients of strongly interacting matter got impetus after the discovery of perfect fluid ever created at ultrarelativistic heavy ion collision experiments. In this article, we have calculated one such coefficient viz. electrical conductivity of the quark gluon plasma (QGP) phase which exhibits a momentum anisotropy. Relativistic Boltzmann's kinetic equation has been solved in the relaxation-time approximation to obtain the electrical conductivity. We have used the quasiparticle description to define the basic properties of QGP. We have compared our model results with the corresponding results obtained in different lattice as well as other model calculations. Furthermore, we extend our model to calculate the electrical conductivity at finite chemical potential.

  6. Electrical conductivity during incipient melting in the oceanic low-velocity zone.

    PubMed

    Sifré, David; Gardés, Emmanuel; Massuyeau, Malcolm; Hashim, Leila; Hier-Majumder, Saswata; Gaillard, Fabrice

    2014-05-01

    The low-viscosity layer in the upper mantle, the asthenosphere, is a requirement for plate tectonics. The seismic low velocities and the high electrical conductivities of the asthenosphere are attributed either to subsolidus, water-related defects in olivine minerals or to a few volume per cent of partial melt, but these two interpretations have two shortcomings. First, the amount of water stored in olivine is not expected to be higher than 50 parts per million owing to partitioning with other mantle phases (including pargasite amphibole at moderate temperatures) and partial melting at high temperatures. Second, elevated melt volume fractions are impeded by the temperatures prevailing in the asthenosphere, which are too low, and by the melt mobility, which is high and can lead to gravitational segregation. Here we determine the electrical conductivity of carbon-dioxide-rich and water-rich melts, typically produced at the onset of mantle melting. Electrical conductivity increases modestly with moderate amounts of water and carbon dioxide, but it increases drastically once the carbon dioxide content exceeds six weight per cent in the melt. Incipient melts, long-expected to prevail in the asthenosphere, can therefore produce high electrical conductivities there. Taking into account variable degrees of depletion of the mantle in water and carbon dioxide, and their effect on the petrology of incipient melting, we calculated conductivity profiles across the asthenosphere for various tectonic plate ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. In moderately aged plates (more than five million years old), incipient melts probably trigger both the seismic low velocities and the high electrical conductivities in the upper part of the asthenosphere, whereas in young plates, where seamount volcanism occurs, a higher degree of melting is expected. PMID:24784219

  7. Electrical conductivity during incipient melting in the oceanic low-velocity zone

    NASA Astrophysics Data System (ADS)

    Sifré, David; Gardés, Emmanuel; Massuyeau, Malcolm; Hashim, Leila; Hier-Majumder, Saswata; Gaillard, Fabrice

    2014-05-01

    The low-viscosity layer in the upper mantle, the asthenosphere, is a requirement for plate tectonics. The seismic low velocities and the high electrical conductivities of the asthenosphere are attributed either to subsolidus, water-related defects in olivine minerals or to a few volume per cent of partial melt, but these two interpretations have two shortcomings. First, the amount of water stored in olivine is not expected to be higher than 50 parts per million owing to partitioning with other mantle phases (including pargasite amphibole at moderate temperatures) and partial melting at high temperatures. Second, elevated melt volume fractions are impeded by the temperatures prevailing in the asthenosphere, which are too low, and by the melt mobility, which is high and can lead to gravitational segregation. Here we determine the electrical conductivity of carbon-dioxide-rich and water-rich melts, typically produced at the onset of mantle melting. Electrical conductivity increases modestly with moderate amounts of water and carbon dioxide, but it increases drastically once the carbon dioxide content exceeds six weight per cent in the melt. Incipient melts, long-expected to prevail in the asthenosphere, can therefore produce high electrical conductivities there. Taking into account variable degrees of depletion of the mantle in water and carbon dioxide, and their effect on the petrology of incipient melting, we calculated conductivity profiles across the asthenosphere for various tectonic plate ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. In moderately aged plates (more than five million years old), incipient melts probably trigger both the seismic low velocities and the high electrical conductivities in the upper part of the asthenosphere, whereas in young plates, where seamount volcanism occurs, a higher degree of melting is expected.

  8. The electrical conductivity during incipient melting in the oceanic low velocity zone

    PubMed Central

    Sifré, David; Gardés, Emmanuel; Massuyeau, Malcolm; Hashim, Leila; Hier-Majumder, Saswata; Gaillard, Fabrice

    2014-01-01

    A low viscosity layer in the upper mantle, the Asthenosphere, is a requirement for plate tectonics1. The seismic low velocities and the high electrical conductivities of the Asthenosphere are attributed either to sub-solidus water-related defects in olivine minerals2-4 or to a few volume percents of partial melt5-8 but these two interpretations have shortcomings: (1) The amount of H2O stored in olivine is not expected to be higher than 50 ppm due to partitioning with other mantle phases9, including pargasite amphibole at moderate temperatures10, and partial melting at high temperatures9; (2) elevated melt volume fractions are impeded by the too cold temperatures prevailing in the Asthenosphere and by the high melt mobility that can lead to gravitational segregation11,12. Here we determined the electrical conductivity of CO2-H2O-rich melts, typically produced at the onset of mantle melting. Electrical conductivity modestly increases with moderate amounts of H2O and CO2 but it dramatically increases as CO2 content exceeds 6 wt% in the melt. Incipient melts, long-expected to prevail in the asthenosphere10,13-15, can therefore trigger its high electrical conductivities. Considering depleted and enriched mantle abundances in H2O and CO2 and their effect on the petrology of incipient melting, we calculated conductivity profiles across the Asthenosphere for various plate ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. In moderately aged plates (>5Ma), incipient melts most likely trigger both the seismic low velocities and the high electrical conductivities in the upper part of the asthenosphere, whereas for young plates4, where seamount volcanism occurs6, higher degree of melting is expected. PMID:24784219

  9. Reconstruction of apparent orthotropic conductivity tensor image using magnetic resonance electrical impedance tomography

    NASA Astrophysics Data System (ADS)

    Sajib, Saurav Z. K.; Kim, Ji Eun; Jeong, Woo Chul; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2015-03-01

    Magnetic resonance electrical impedance tomography visualizes current density and/or conductivity distributions inside an electrically conductive object. Injecting currents into the imaging object along at least two different directions, induced magnetic flux density data can be measured using a magnetic resonance imaging scanner. Without rotating the object inside the scanner, we can measure only one component of the magnetic flux density denoted as Bz. Since the biological tissues such as skeletal muscle and brain white matter show strong anisotropic properties, the reconstruction of anisotropic conductivity tensor is indispensable for the accurate observations in the biological systems. In this paper, we propose a direct method to reconstruct an axial apparent orthotropic conductivity tensor by using multiple Bz data subject to multiple injection currents. To investigate the anisotropic conductivity properties, we first recover the internal current density from the measured Bz data. From the recovered internal current density and the curl-free condition of the electric field, we derive an over-determined matrix system for determining the internal absolute orthotropic conductivity tensor. The over-determined matrix system is designed to use a combination of two loops around each pixel. Numerical simulations and phantom experimental results demonstrate that the proposed algorithm stably determines the orthotropic conductivity tensor.

  10. Reconstruction of apparent orthotropic conductivity tensor image using magnetic resonance electrical impedance tomography

    SciTech Connect

    Sajib, Saurav Z. K.; Kim, Ji Eun; Jeong, Woo Chul; Kim, Hyung Joong; Woo, Eung Je; Kwon, Oh In

    2015-03-14

    Magnetic resonance electrical impedance tomography visualizes current density and/or conductivity distributions inside an electrically conductive object. Injecting currents into the imaging object along at least two different directions, induced magnetic flux density data can be measured using a magnetic resonance imaging scanner. Without rotating the object inside the scanner, we can measure only one component of the magnetic flux density denoted as B{sub z}. Since the biological tissues such as skeletal muscle and brain white matter show strong anisotropic properties, the reconstruction of anisotropic conductivity tensor is indispensable for the accurate observations in the biological systems. In this paper, we propose a direct method to reconstruct an axial apparent orthotropic conductivity tensor by using multiple B{sub z} data subject to multiple injection currents. To investigate the anisotropic conductivity properties, we first recover the internal current density from the measured B{sub z} data. From the recovered internal current density and the curl-free condition of the electric field, we derive an over-determined matrix system for determining the internal absolute orthotropic conductivity tensor. The over-determined matrix system is designed to use a combination of two loops around each pixel. Numerical simulations and phantom experimental results demonstrate that the proposed algorithm stably determines the orthotropic conductivity tensor.

  11. Electrical and thermal conduction in ultra-thin freestanding atomic layer deposited W nanobridges.

    PubMed

    Eigenfeld, Nathan T; Gertsch, Jonas C; Skidmore, George D; George, Steven M; Bright, Victor M

    2015-11-14

    Work presented here measures and interprets the electrical and thermal conductivities of atomic layer deposited (ALD) free-standing single film and periodic tungsten and aluminum oxide nanobridges with thicknesses from ?5-20 nm and ?3-13 nm, respectively. Electrical conductivity of the W films is reduced by up to 99% from bulk, while thermal conductivity is reduced by up to 91%. Results indicate phonon contribution to thermal conductivity is dominant in these ALD films and may be substantially reduced by the incorporation of periodicity in the ALD W/Al2O3 nanolaminates. Additionally, thin film conduction modeling demonstrates nano-structured grain features largely dictate electron and phonon conduction in ALD W. New fabrication methods have allowed for the development of free-standing ultra-thin structures with layers on the order of several nanometers utilizing ALD. While the literature contains diverse studies of the physical properties of thin films prepared by traditional micro-fabrication sputtering or chemical vapor deposition techniques, there remains little data on freestanding structures containing ALD generated materials. Specifically, knowledge of the electrical and thermal conductivity of ALD generated materials will aid in the future development of ultra-thin nano-devices. PMID:26463738

  12. Ab initio study of high pressure liquid silica: electrical conductivity and structure.

    NASA Astrophysics Data System (ADS)

    Stixrude, L. P.; Scipioni, R.

    2014-12-01

    The transport properties of silicate liquids are important for understanding the thermal evolution of giant impact targets, magma oceans, and the possibility of silicate dynamos in the early Earth and in other rocky planets. However, little is known about the electrical conductivity of silicate liquids over the relevant pressure-temperature regime. Here, we focus on silica as one of the most abundant components and a model system for understanding transport properties in silicates. We perform first principles molecular dynamics simulations over the pressure-temperature encompassing that of the early Earth, and compute the electrical conductivity via the Green-Kubo formula. The electrical conductivity of the liquid substantially exceeds that of crystalline phases at all conditions. We find that along isotherms the conductivity of silica liquid reaches a maximum near 40 percent compression, remarkably similar to the compression at which 5-fold Si-O coordination is most abundant. The conductivity decreases upon further compression. The conductivity increases rapidly with increasing temperature at all pressures. We explore the underlying physical mechanisms of the computed variations of conductivity with pressure and temperature and discuss the implications of our results for magnetic field generation in basal magma oceans.

  13. Effects of Extremity Elevation and Health Factors On Soft Tissue Electrical Conductivity

    NASA Astrophysics Data System (ADS)

    Feldkamp, J. R.; Heller, J.

    2009-01-01

    Two clinical studies were completed using an auto-tuned induction coil conductivity sensor (ICCS) to determine the effects of a variety of factors on the electrical conductivity of soft tissue. In addition to fifteen "subject variables" such as blood pressure and others, we have specifically focused on considering the role of such factors as gender, age, BMI, smoking and elevation of extremities. Measurements were made at seven sites on either side of the body for a total of fourteen. Higher conductivities were obtained for women than men at all sites. At five sites, where age was a significant factor, conductivity was found to decline with increased age. Interestingly, smokers as a group tended to have reduced conductivity, suggesting that aging and smoking have similar effects on the microvasculature of soft tissue. Generally speaking, electrical conductivity is observed to increase in response to increased elevation at sites located on extremities. Considering just healthy adults, a definite pattern of elevation-induced electrical conductivity displacement emerges when subjects are flagged according to high, low or moderate blood pressure. We suggest that violations of this pattern may provide a method for identifying those individuals in an early stage of peripheral vascular disease.

  14. Model simulations of strong atmospheric conductivity disturbances and induced responses of the Global Electric Circuit

    NASA Astrophysics Data System (ADS)

    Baumgaertner, A. J.; Lehto, E.; Neely, R. R.; English, J. M.; Zhu, Y.; Lucas, G.; Thayer, J. P.

    2013-12-01

    Electrical conductivity in the troposphere and stratosphere is an important quantity that determines the distribution of currents in the GEC (Global Electric Circuit), as well as the potential difference between the Earth and the ionosphere. Recently, progress in modeling atmospheric conductivity has been achieved by integrating the conductivity calculation into an AC-GCM (atmospheric chemistry general circulation model), which provides all relevant data. In this study, WACCM (Whole Atmosphere Community Climate Model) is used for conductivity calculations and an analysis of the effects of strong disturbances on the GEC. This includes volcanic eruptions of Pinatubo in 1991 and the super volcano Toba, polar stratospheric clouds, radioactive releases, and the recent strong galactic cosmic ray maximum. In general, there is a decrease in conductivity from enhanced aerosol number densities, resulting from volcanic eruptions or polar stratospheric clouds. Conductivity is increased by additional ionization sources such as radioactive releases, or galactic cosmic ray increases such as during the last solar minimum. The effects of such events on conductivity, column and total resistance, and estimate effects on current distribution and the earth-ionosphere potential difference will be quantified. Percentage change in conductivity at 20 km altitude two months after the Toba volcanic eruption (WACCM model simulation). The enhanced aerosol concentrations lead to a "conductivity hole" between 30°S and 45° N.

  15. Electrical transport and ac conductivity properties of hydrogenated annealing V-doped ZnO

    NASA Astrophysics Data System (ADS)

    Liu, S. H.; Huang, J. C. A.; Lin, C. R.; Qi, X.

    2009-04-01

    The hydrogenated annealing effects on structure, magnetism, electrical transport, and ac conductivity for V-doped ZnO powders have been systematically investigated. Room temperature ferromagnetism has been observed for the hydrogenated V:ZnO powders. The saturation magnetization increases with hydrogenated annealing temperature (Tha). By the analysis of electrical transport and ac conductivity, the V:ZnO powders show Efros's variable range hopping and the density of microstructural defects increases with Tha. The results suggest that the fluctuation of the magnetization is strongly correlated with the defect density in V:ZnO powders.

  16. On the origin of electrical conductivity in the bio-electronic material melanin

    NASA Astrophysics Data System (ADS)

    Bernardus Mostert, A.; Powell, Ben J.; Gentle, Ian R.; Meredith, Paul

    2012-02-01

    The skin pigment melanin is one of a few bio-macromolecules that display electrical and photo-conductivity in the solid-state. A model for melanin charge transport based on amorphous semiconductivity has been widely accepted for 40 years. In this letter, we show that a central pillar in support of this hypothesis, namely experimental agreement with a hydrated dielectric model, is an artefact related to measurement geometry and non-equilibrium behaviour. Our results cast significant doubt on the validity of the amorphous semiconductor model and are a reminder of the difficulties of electrical measurements on low conductivity, disordered organic materials.

  17. Proton-irradiation-induced anomaly in the electrical conductivity of a hydrogen-bonded ferroelastic system

    SciTech Connect

    Kim, Se-Hun; Lee, Kyu Won; Lee, Cheol Eui; Lee, Kwang-Sei

    2009-11-01

    An anomalous abrupt drop in the electrical conductivity has been observed at the ferroelastic phase transition of a proton-irradiated system of hydrogen-bonded TlH{sub 2}PO{sub 4}. As a result of the high-resolution {sup 31}P NMR chemical-shift measurements, distinct changes in the atomic displacements due to the irradiation were identified in the ferroelastic and paraelastic phases. Besides, {sup 1}H NMR spin-spin relaxation measurements revealed a change due to the irradiation in the proton dynamics at the ferroelastic phase transition, apparently accounting for the much-reduced electrical conductivity in the paraelastic phase of the irradiated system.

  18. Fuel cell components and systems having carbon-containing electrically-conductive hollow fibers

    DOEpatents

    Langry, Kevin C; Farmer, Joseph C

    2015-04-28

    A method, according to one embodiment, includes acquiring a structure having an ionically-conductive, electrically-resistive electrolyte/separator layer covering an inner or outer surface of a carbon-containing electrically-conductive hollow fiber and a catalyst along one side thereof, adding an anode that extends along at least part of a length of the structure, and adding a cathode that extends along at least part of the length of the structure, the cathode being on an opposite side of the hollow fiber as the anode.

  19. Electrically conductive doped block copolymer of polyacetylene and polyisoprene. [Soluble in organic solvents

    DOEpatents

    Aldissi, M.

    1984-06-27

    An electrically conductive block copolymer of polyisoprene and polyacetylene 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.

  20. Breakdown characteristics of an isolated conducting object in a uniform electric field

    NASA Technical Reports Server (NTRS)

    Grothaus, M. G.; Trost, T. F.

    1986-01-01

    A laboratory experiment was conducted to determine the physical processes involved in the electrical breakdown of a particular spark gap arrangement. The gap consists of an isolated conducting ellipsoid located midway between two large flat electrodes. Gradual increase of the applied electric field, E, in the gap produces corona on the ellipsoid tips followed by flashover in a leader-arc sequence. The leader phase consists of the abrupt formation of ionized channels which partially bridge the gap and then decay prior to the arc. Measurements of dE/dt and of current were made, and photographs were taken with an image converter. Experimental parameters are listed.

  1. Electrical conductivity of activated carbon-metal oxide nanocomposites under compression: a comparison study.

    PubMed

    Barroso-Bogeat, A; Alexandre-Franco, M; Fernández-González, C; Macías-García, A; Gómez-Serrano, V

    2014-12-01

    From a granular commercial activated carbon (AC) and six metal oxide (Al2O3, Fe2O3, SnO2, TiO2, WO3 and ZnO) precursors, two series of AC-metal oxide nanocomposites were prepared by wet impregnation, oven-drying at 120 °C, and subsequent heat treatment at 200 or 850 °C in an inert atmosphere. Here, the electrical conductivity of the resulting products was studied under moderate compression. The influence of the applied pressure, sample volume, mechanical work, and density of the hybrid materials was thoroughly investigated. The DC electrical conductivity of the compressed samples was measured at room temperature by the four-probe method. Compaction assays suggest that the mechanical properties of the nanocomposites are largely determined by the carbon matrix. Both the decrease in volume and the increase in density were relatively small and only significant at pressures lower than 100 kPa for AC and most nanocomposites. In contrast, the bulk electrical conductivity of the hybrid materials was strongly influenced by the intrinsic conductivity, mean crystallite size, content and chemical nature of the supported phases, which ultimately depend on the metal oxide precursor and heat treatment temperature. The supported nanoparticles may be considered to act as electrical switches either hindering or favouring the effective electron transport between the AC cores of neighbouring composite particles in contact under compression. Conductivity values as a rule were lower for the nanocomposites than for the raw AC, all of them falling in the range of semiconductor materials. With the increase in heat treatment temperature, the trend is toward the improvement of conductivity due to the increase in the crystallite size and, in some cases, to the formation of metals in the elemental state and even metal carbides. The patterns of variation of the electrical conductivity with pressure and mechanical work were slightly similar, thus suggesting the predominance of the pressure effects rather than the volume ones. PMID:25331935

  2. Electrical conductivity as a test for the integrity of latex gloves

    SciTech Connect

    Stampfer, J.F.; Kissane, R.J.; Schauer, S.M.

    1993-02-01

    Surgical latex gloves have been used to protect patients against bacterial infections introduced by health-care workers. As a result of the Acquired Immune Deficiency Syndrome (AIDS) epidemic, the concern has shifted, with more emphasis on the protection of the health-care worker from the patient. These gloves often have defects, holes, which allow bacteria to penetrate. There are a number of methods to test the integrity of these gloves before they are donned. The present standard test is to fill the glove with 1000 ml of water and visually inspect the exterior for water leaks. Another method allows the gloves to be tested while being worn. This is done by measuring the electrical conductivity through the latex, from the hand to an external conductive solution. We have investigated the use of electrical conductivity to test sterile latex gloves, both with and without holes. We have studied various phenomena associated with this testing and conducted simultaneous electrical and viral penetration tests. Our conclusions are as follows. (1) Electrical conductivity test method for gloves while they are being worn is very dependent on the specific glove being tested, primarily on the conductivity of the intact glove. (2) In the best of cases, reliable results could be expected for only about one hour of wear and for holes larger than 10s of [mu]ms. (3) There are practical problems that may disqualify the electrical conductivity test for routine use. (4) The test may prove to be valuable as a QA test procedure for nonconductive materials and garments made from these materials because it has greater sensitivity than presently used methods. (5) The effective sizes of holes in latex increase much faster when the latex is stretched than would be predicted from the elongation of the latex.

  3. Hygrothermal Stability of Electrical Contacts Made from Silver and Graphite Electrically Conductive Pastes

    E-print Network

    Chung, Deborah D.L.

    , University at Buffalo, State University of New York, Buffalo, NY14260-4400, USA. 2.--E-mail: ddlchung@buffalo in water at 15°C and 40°C. The pastes are silver paint, silver paint with a nonconductive epoxy overcoat is even less durable than silver epoxy, due to its being water based. Key words: Electrical contact

  4. Inductive Measurement of Plasma Jet Electrical Conductivity (MSFC Center Director's discretionary Fund). Part 2

    NASA Technical Reports Server (NTRS)

    Turner, M. W.; Hawk, C. W.; Litchford, R. J.

    2001-01-01

    Measurement of plasma jet electrical conductivity has utility in the development of explosively driven magnetohydrodynamic (MHD) energy converters as well as magnetic flux compression reaction chambers for nuclear/chemical pulse propulsion and power. Within these types of reactors, the physical parameter of critical importance to underlying MHD processes is the magnetic Reynolds number, the value of which depends upon the product of plasma electrical conductivity and velocity. Therefore, a thorough understanding of MHD phenomena at high magnetic Reynolds number is essential, and methods are needed for the accurate and reliable measurement of electrical conductivity in high-speed plasma jets. It is well known that direct measurements using electrodes suffer from large surface resistance, and an electrodeless technique is desired. To address this need, an inductive probing scheme, originally developed for shock tube studies, has been adapted. In this method, the perturbation of an applied magnetic field by a plasma jet induces a voltage in a search coil, which, in turn, can be used to infer electrical conductivity through the inversion of a Fredholm integral equation of the first kind. A 1-in.-diameter probe using a light-gas gun. Exploratory laboratory experiments were carried out using plasma jets expelled from 15-g shaped charges. Measured conductivities were in the range of 4 kS/m for unseeded octol charges and 26 kS/m for seeded octol charges containing 2-percent potassium carbonate by mass.

  5. Electrical conductivity of orthopyroxene: implications for the water content of the asthenosphere.

    PubMed

    Dai, Lidong; Karato, Shun-ichiro

    2009-01-01

    Electrical conductivity of minerals is sensitive to water content and hence can be used to infer the water content in the mantle. However, previous studies to infer the water content in the upper mantle were based on pure olivine model of the upper mantle. Influence of other minerals particularly that of orthopyroxene needs to be included to obtain a better estimate of water content in view of the high water solubility in this mineral. Here we report new results of electrical conductivity measurements on orthopyroxene, and apply these results to estimate the water content of the upper mantle of Earth. We found that the electrical conductivity of orthopyroxene is enhanced by the addition of water in a similar way as other minerals such as olivine and pyrope garnet. Using these new results, we calculate the electrical conductivity of pyrolite mantle as a function of water content and temperature incorporating the temperature and water fugacity-dependent hydrogen partitioning. Reported values of asthenosphere conductivity of 4x10(-2)-10(-1) S/m corresponds to the water content of 0.01-0.04 wt%, a result in good agreement with the petrological model of the upper mantle. PMID:20009379

  6. Electrical conductivity of orthopyroxene: Implications for the water content of the asthenosphere

    PubMed Central

    Dai, Lidong; Karato, Shun-ichiro

    2009-01-01

    Electrical conductivity of minerals is sensitive to water content and hence can be used to infer the water content in the mantle. However, previous studies to infer the water content in the upper mantle were based on pure olivine model of the upper mantle. Influence of other minerals particularly that of orthopyroxene needs to be included to obtain a better estimate of water content in view of the high water solubility in this mineral. Here we report new results of electrical conductivity measurements on orthopyroxene, and apply these results to estimate the water content of the upper mantle of Earth. We found that the electrical conductivity of orthopyroxene is enhanced by the addition of water in a similar way as other minerals such as olivine and pyrope garnet. Using these new results, we calculate the electrical conductivity of pyrolite mantle as a function of water content and temperature incorporating the temperature and water fugacity-dependent hydrogen partitioning. Reported values of asthenosphere conductivity of 4 × 10?2?10?1 S/m corresponds to the water content of 0.01–0.04 wt%, a result in good agreement with the petrological model of the upper mantle. PMID:20009379

  7. The effect of iron spin transition on electrical conductivity of (Mg,Fe)O magnesiowüstite.

    PubMed

    Ohta, Kenji; Hirose, Kei; Onoda, Suzue; Shimizu, Katsuya

    2007-05-01

    We measured the electrical conductivity of Mg0.81Fe0.19O magnesiowüstite, one of the important minerals comprising Earth's lower mantle, at high pressures up to 135 GPa and 300 K in a diamond-anvil cell (DAC). The results demonstrate that the electrical conductivity increases with increasing pressure to about 60 GPa and exhibits anomalous behavior at higher pressures; it conversely decreases to around 80 GPa and again increases very mildly with pressure. These observed changes may be explained by the high-spin to low-spin transition of iron in magnesiowüstite that was previously reported to occur in a similar pressure range. A very small pressure effect on the electrical conductivity above 80 GPa suggests that a dominant conduction mechanism changes by this electronic spin transition. The electrical conductivity below 2000-km depth in the mantle may be much smaller than previously thought, since the spin transition takes place also in (Mg,Fe)SiO3 perovskite. PMID:24019587

  8. Electrical and thermal conduction in atomic layer deposition nanobridges down to 7 nm thickness.

    PubMed

    Yoneoka, Shingo; Lee, Jaeho; Liger, Matthieu; Yama, Gary; Kodama, Takashi; Gunji, Marika; Provine, J; Howe, Roger T; Goodson, Kenneth E; Kenny, Thomas W

    2012-02-01

    While the literature is rich with data for the electrical behavior of nanotransistors based on semiconductor nanowires and carbon nanotubes, few data are available for ultrascaled metal interconnects that will be demanded by these devices. Atomic layer deposition (ALD), which uses a sequence of self-limiting surface reactions to achieve high-quality nanolayers, provides an unique opportunity to study the limits of electrical and thermal conduction in metal interconnects. This work measures and interprets the electrical and thermal conductivities of free-standing platinum films of thickness 7.3, 9.8, and 12.1 nm in the temperature range from 50 to 320 K. Conductivity data for the 7.3 nm bridge are reduced by 77.8% (electrical) and 66.3% (thermal) compared to bulk values due to electron scattering at material and grain boundaries. The measurement results indicate that the contribution of phonon conduction is significant in the total thermal conductivity of the ALD films. PMID:22224582

  9. Dynamics of Space Charge Polarization and Electrical Conduction in Low Alkali Boroaluminosilicate Glasses

    NASA Astrophysics Data System (ADS)

    Dash, Priyanka

    Low alkali boroaluminosilicate glasses are of tremendous interest for high temperature electronics primarily due to their superior high temperature dielectric properties and extraordinary energy densities. Therefore, evaluating factors causing electrical conduction in these materials is of great importance since it has direct correlation with the device reliability and performance. This research focuses on understanding dynamics of space charge polarization and mechanisms controlling electrical conduction in these glasses. Both DC and AC characterization techniques were developed to elucidate electronic and ionic conduction mechanisms under a variety of temperatures, electric field and frequency conditions. Ionic conduction and space charge polarization have been studied in low alkali glasses as a function of electric field and temperature by thermally stimulated depolarization and low frequency impedance spectroscopy. Moreover, due to the low alkali content in these glasses, it was possible to study the transport properties of alkaline earth ions in multicomponent silicate glasses. It was observed that the potential energy barrier height for ionic hopping was reduced at high electric field. Impedance spectroscopy and second harmonic generation microscopy techniques were applied to determine the thickness and electric field distribution across the cation depleted layer that was generated during the thermoelectric poling. Both of these measurements show that the depletion layer thickness depends on the poling conditions and the intrinsic breakdown strength of the material. In addition, a relationship between the charge and electric field distribution in the depletion layer was determined for a number of glasses with different alkali content. The high breakdown strength of these glasses facilitated the study of electronic conduction under fields greater than 108 V/m. Conduction under these high fields was investigated using high field thermally stimulated depolarization current measurements. The electrons participating in the high field conduction were generated in the depletion layer through Poole-Frenkel emission. This involves field-enhanced excitation of electrons from the trapped states to the conduction band of the glass. It is suggested that high field intrinsic breakdown in thin alkali free boroaluminosilicate glasses may occur when the conduction band gets populated by electrons emitted through Poole-Frenkel emission. Consequently breakdown can occur through an avalanche effect.

  10. Serotonin Regulates Electrical Coupling via Modulation of Extrajunctional Conductance: H-current

    PubMed Central

    Szabo, Theresa M.; Caplan, Jonathan S.; Zoran, Mark J.

    2010-01-01

    Synaptic strength can be highly variable from animal to animal within a species or over time within an individual. The process of synaptic plasticity induced by neuromodulatory agents might be unpredictable when the underlying circuits subject to modulation are themselves inherently variable. Serotonin (5-hydroxytryptomine; 5HT) and serotonergic signaling pathways are important regulators of animal behavior and are pharmacological targets in a wide range of neurological disorders. We have examined the effect of 5HT on electrical synapses possessing variable coupling strengths. While 5HT decreased electrical coupling at synapses with weak electrical connectivity, synapses with strong electrical coupling were less affected by 5HT treatment, as follows from the equations used for calculating coupling coefficients. The fact that the modulatory effect of 5HT on electrical connections was negatively correlated with the strength of electrical coupling suggests that the degree of electrical coupling within a neural network impacts subsequent neuromodulation of those synapses. Biophysical studies indicated that these effects were primarily due to 5HT-induced modulation of membrane currents that indirectly affect junctional coupling at synaptic contacts. In support of these experimental analyses, we created a simple model of coupled neurons to demonstrate that modulation of electrical coupling could be due solely to 5HT effects on H-channel conductance. Therefore, variability in the strength of electrical coupling in neural circuits can determine the pharmacological effect of this neuromodulatory agent. PMID:20599836

  11. Correlation of Seebeck coefficient and electric conductivity in polyaniline and polypyrrole

    SciTech Connect

    Mateeva, N.; Niculescu, H.; Schlenoff, J.; Testardi, L.R.

    1998-03-01

    We have measured the Seebeck coefficient and electric conductivity in the air-stable conducting polymers polyaniline and polypyrrole at different doping levels. We find, at 300 K, the general correlation that the logarithm of the electrical conductivity varies linearly with the Seebeck coefficient on doping, but with a proportionality substantially in excess of a prediction from simple theory for a single type of mobile carrier. The correlation is unexpected in its universality and unfavorable in its consequences for thermoelectric applications. A standard model suggests that conduction by carriers of both signs may occur in these doped polymers, which thus leads to reduced thermoelectric efficiency. We also show that polyacetylene (which is not air stable), does exhibit the correlation with the expected proportionality, and, thus, its properties could be more favorable for thermoelectricity. {copyright} {ital 1998 American Institute of Physics.}

  12. Electric conductivity and aggregation of anthracite and graphite particles in concretes

    SciTech Connect

    E.A. Fanina; A.N. Lopanov

    2009-02-15

    A statistical model of the electric conductivity of a heterogeneous system based on coal and a binding agent is presented. In this system, a conductive phase appears because of particle aggregation. The model was tested in the systems of anthracite and graphite in cement stone. The consistency between the experimental and calculated electric conductivities with a correlation coefficient higher than 0.9 was found on a linear interpolation of model parameters. It was found that the presence of a surfactant (cetylpyridinium chloride) and a high-molecular-weight compound (polyvinyl acetate) changed the number of particles in anthracite and graphite aggregates to affect the specific conductivity of the heterogeneous system. 9 refs., 5 figs., 1 tab.

  13. Tunable electrical conductivity in metal-organic framework thin-film devices.

    PubMed

    Talin, A Alec; Centrone, Andrea; Ford, Alexandra C; Foster, Michael E; Stavila, Vitalie; Haney, Paul; Kinney, R Adam; Szalai, Veronika; El Gabaly, Farid; Yoon, Heayoung P; Léonard, François; Allendorf, Mark D

    2014-01-01

    We report a strategy for realizing tunable electrical conductivity in metal-organic frameworks (MOFs) in which the nanopores are infiltrated with redox-active, conjugated guest molecules. This approach is demonstrated using thin-film devices of the MOF Cu3(BTC)2 (also known as HKUST-1; BTC, benzene-1,3,5-tricarboxylic acid) infiltrated with the molecule 7,7,8,8-tetracyanoquinododimethane (TCNQ). Tunable, air-stable electrical conductivity over six orders of magnitude is achieved, with values as high as 7 siemens per meter. Spectroscopic data and first-principles modeling suggest that the conductivity arises from TCNQ guest molecules bridging the binuclear copper paddlewheels in the framework, leading to strong electronic coupling between the dimeric Cu subunits. These ohmically conducting porous MOFs could have applications in conformal electronic devices, reconfigurable electronics, and sensors. PMID:24310609

  14. An origin of good electrical conduction in La4BaCu5O13+?

    NASA Astrophysics Data System (ADS)

    Mori, Daiki; Asai, Shinichiro; Terasaki, Ichiro; Okazaki, Ryuji; Yasui, Yukio; Parkkima, Outi; Karppinen, Maarit

    2015-07-01

    We have prepared a set of polycrystalline samples of the metallic copper oxide La4BaCu5-xCoxO13+? (0 ? x ? 0.35) and have measured the resistivity from 4 to 800 K. All the resistivities show metallic temperature dependence with a small magnitude less than 2 m? cm at 800 K, indicating that the metallic conduction is robust against impurities. The robust metallic conduction further suggests that this class of oxide is a promising candidate for electrical leads at high temperature, which might replace platinum. A detailed measurement and analysis on the Hall resistivity have revealed that at least two components are responsible for the electrical conduction, in which a large number of electrons of moderate mobility coexist with a much smaller number of holes of extremely high mobility. This large electron density well screens the impurity potential and retains the metallic conduction against 7% impurity doping.

  15. A novel approach to model hydraulic and electrical conductivity in fractal porous media

    NASA Astrophysics Data System (ADS)

    Ghanbarian, B.; Daigle, H.; Sahimi, M.

    2014-12-01

    Accurate prediction of conductivity in partially-saturated porous media has broad applications in various phenomena in porous media, and has been studied intensively since the 1940s by petroleum, chemical and civil engineers, and hydrologists. Many of the models developed in the past are based on the bundle of capillary tubes. In addition, pore network models have also been developed for simulating multiphase fluid flow in porous media and computing the conductivity in unsaturated porous media. In this study, we propose a novel approach using concepts from the effective-medium approximation (EMA) and percolation theory to model hydraulic and electrical conductivity in fractal porous media whose pore-size distributions exhibit power-law scaling. In our approach, the EMA, originally developed for predicting electrical conductivity of composite materials, is used to predict the effective conductivity, from complete saturation to some intermediate water content that represents a crossover point. Below the crossover water content, but still above a critical saturation (percolation threshold), a universal scaling predicted by percolation theory, a power law that expresses the dependence of the conductivity on the water content (less a critical water saturation) with an exponent of 2, is invoked to describe the effective conductivity. In order to evaluate the accuracy of the approach, experimental data were used from the literature. The predicted hydraulic conductivities for most cases are in excellent agreement with the data. In a few cases the theory underestimates the hydraulic conductivities, which correspond to porous media with very broad pore-size distribution in which the largest pore radius is more than 7 orders of magnitude greater than the smallest one. The approach is also used to predict the saturation dependence of the electrical conductivity for experiments in which capillary pressure data are available. The results indicate that the universal scaling of the electrical conductivity is valid from the percolation threshold all the way up to the complete saturation point. Our results confirm those reported previously by Ewing and Hunt (2006) who argued that the electrical conductivity should follow universal scaling over the entire range of saturation.

  16. Inhibition and recovery of continuous electric field application on the activity of anammox biomass.

    PubMed

    Qiao, Sen; Yin, Xin; Zhou, Jiti; Furukawa, Kenji

    2014-07-01

    In this study, the effects of electric field on the activity of anammox biomass were investigated. In batch mode, experimental results demonstrated that the nitrogen removal rate enhanced by 25.6 % compared with the control experiment at the electric field of 2 V/cm with application time of 20 min. However, continuous application (24 h) of electric field impacted a mal-effect on anammox biomass during the intensity between 1 and 4 V/cm. After the electric field was removed, the activity of anammox biomass could recover within 2 weeks. This implied that the mal-effect of electric field on anammox biomass was reversible. The decrease of heme c contents and crude enzyme activity demonstrated to be the main reason for the depress of the anammox biomass activity. Transmission electron microscope observation also proved the morphological change of anammox biomass under electric field. PMID:24258098

  17. Charge density dependent two-channel conduction in organic electric double layer transistors (EDLTs).

    PubMed

    Xie, Wei; Liu, Feilong; Shi, Sha; Ruden, P Paul; Frisbie, C Daniel

    2014-04-23

    A transport model based on hole-density-dependent trapping is proposed to explain the two unusual conductivity peaks at surface hole densities above 10(13) cm(-2) in rubrene electric double layer transistors (EDLTs). Hole transport in rubrene is described to occur via multiple percolation pathways, where conduction is dominated by transport in the free-site channel at low hole density, and in the trap-site channel at larger hole density. PMID:24496822

  18. Electronic energy gap of molecular hydrogen from electrical conductivity measurements at high shock pressures

    NASA Technical Reports Server (NTRS)

    Nellis, W. J.; Mitchell, A. C.; Mccandless, P. C.; Erskine, D. J.; Weir, S. T.

    1992-01-01

    Electrical conductivities were measured for liquid D2 and H2 shock compressed to pressures of 10-20 GPa (100-200 kbar), molar volumes near 8 cu cm/mol, and calculated temperatures of 2900-4600 K. The semiconducting energy gap derived from the conductivities is 12 eV, in good agreement with recent quasi-particle calculations and with oscillator frequencies measured in diamond-anvil cells.

  19. Slow oscillations of KATP conductance in mouse pancreatic islets provide support for electrical bursting driven by metabolic oscillations

    E-print Network

    Slow oscillations of KATP conductance in mouse pancreatic islets provide support for electrical of KATP conductance in mouse pancreatic islets provide support for electrical bursting driven by metabolic oscillations in metabolism mediate slow electrical oscillations in mouse pancreatic islets by causing

  20. Electrical conductivity and electron-spin resonance in oxidatively stabilized polyacrylonitrile subjected to elevated temperature

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.

    1981-01-01

    Electrical conductivity and electron spin resonance measurements are presented for oxidatively stabilized polyacrylonitrile (PAN) fibers subjected to heat treatment at temperatures ranging from 700 to 950 K. Conductivity measurements made at temperatures between 77 and 523 K reveal that PAN fibers heat treated in vacuum behave as semiconductors, with a room-temperature conductivity dominated by the contributions of impurity states, with an activation energy of 88 kcal/mole. A decrease in conductivity is observed upon air which is attributed to a decrease in the electron-phonon scattering time. ESR spectra indicate that conducting pathways having metallic properties are formed at temperatures as low as 715 K, although the contribution of these pathways to the room-temperature conductivity is extremely small next to the contribution of localized spin centers.

  1. Sub-millimeter resolution electrical conductivity images of brain tissues using magnetic resonance-based electrical impedance tomography

    NASA Astrophysics Data System (ADS)

    Oh, Tong In; Kim, Hyun Bum; Jeong, Woo Chul; Sajib, Saurav Z. K.; Kyung, Eun Jung; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2015-07-01

    Recent magnetic resonance (MR)-based electrical impedance tomography (MREIT) of in vivo animal and human subjects enabled the imaging of electromagnetic properties, such as conductivity and permittivity, on tissue structure and function with a few millimeter pixel size. At those resolutions, the conductivity contrast might be sufficient to distinguish different tissue type for certain applications. Since the precise measurement of electrical conductivity under the tissue levels can provide alternative information in a wide range of biomedical applications, it is necessary to develop high-resolution MREIT technique to enhance its availability. In this study, we provide the experimental evaluation of sub-millimeter resolution conductivity imaging method using a 3T MR scanner combined with a multi-echo MR pulse sequence, multi-channel RF coil, and phase optimization method. From the phantom and animal imaging results, sub-millimeter resolution exhibited similar signal-to-noise ratio of MR magnitude and noise levels in magnetic flux density comparing to the existing millimeter resolution. The reconstructed conductivity images at sub-millimeter resolution can distinguish different brain tissues with a pixel size as small as 350 ?m.

  2. Electrical conductivity and permeability of partially molten mantle rocks: results from digital rock physics experiments

    NASA Astrophysics Data System (ADS)

    Miller, K.; Montesi, L.; Zhu, W.

    2014-12-01

    Estimates of overall melt content beneath mid-ocean ridges inferred from magnetotelluric tomography (MT) studies vary widely between 1 and 10 vol. %. Much of this variation may arise from a lack of understanding about how melt geometry influences the bulk electrical conductivity of partially molten mantle rock, especially at low melt fraction. We present results from experiments in which we numerically calculate the electrical conductivity and permeability using high-resolution, three-dimensional melt geometries of olivine-basalt systems obtained via synchrotron X-ray microtomography (SX?T). Starting materials consist of San Carlos olivine and Fo90 basalt mixed in various proportions to achieve nominal melt fraction of 0.02 to 0.20 when melted. Samples were prepared by isostatically pressing samples at 1.5GPa and 1350°C for a minimum of 1 week (Zhu et al., 2011; Science) and then quenched, turning the melt to basaltic glass. Samples were imaged using SX?T at the Advanced Photon Source at Argonne National Labs to obtain three-dimensional, 700 nm-per-pixel digital reconstructions. Grayscale data was segmented using Avizo® software (Miller et al., 2014; EPSL), and binary images were used as computational domains in numerical experiments to determine bulk electrical conductivity and permeability. Numerical experiments were carried out on several statistically representative subvolumes per sample using finite difference techniques. Olivine and melt are treated as conductive and insulative phases, respectively. To calculate conductivity, Laplace's equation is solved for the electric potential, assuming zero electric flux across phase boundaries. Ohm's Law yields the bulk conductivity of the sample. To calculate permeability, Stokes' equations are solved using the artificial compressibility method on a staggered grid. Darcy's law then gives the permeability of the subvolume. We fit permeability and electrical conductivity values to power laws in order to establish empirical relationships with melt fraction. We compare with experimental studies. By linking permeability and electrical conductivity to melt content, we are able to better guide interpretations of geophysical data and constrain melt connectivity and transport at mid-ocean ridges.

  3. Experimental Determination and Thermodynamic Modeling of Electrical Conductivity of SRS Waste Tank Supernate

    SciTech Connect

    Pike, J.; Reboul, S.

    2015-06-01

    SRS High Level Waste Tank Farm personnel rely on conductivity probes for detection of incipient overflow conditions in waste tanks. Minimal information is available concerning the sensitivity that must be achieved such that that liquid detection is assured. Overly sensitive electronics results in numerous nuisance alarms for these safety-related instruments. In order to determine the minimum sensitivity required of the probe, Tank Farm Engineering personnel need adequate conductivity data to improve the existing designs. Little or no measurements of liquid waste conductivity exist; however, the liquid phase of the waste consists of inorganic electrolytes for which the conductivity may be calculated. Savannah River Remediation (SRR) Tank Farm Facility Engineering requested SRNL to determine the conductivity of the supernate resident in SRS waste Tank 40 experimentally as well as computationally. In addition, SRNL was requested to develop a correlation, if possible, that would be generally applicable to liquid waste resident in SRS waste tanks. A waste sample from Tank 40 was analyzed for composition and electrical conductivity as shown in Table 4-6, Table 4-7, and Table 4-9. The conductivity for undiluted Tank 40 sample was 0.087 S/cm. The accuracy of OLI Analyzer™ was determined using available literature data. Overall, 95% of computed estimates of electrical conductivity are within ±15% of literature values for component concentrations from 0 to 15 M and temperatures from 0 to 125 °C. Though the computational results are generally in good agreement with the measured data, a small portion of literature data deviates as much as ±76%. A simplified model was created that can be used readily to estimate electrical conductivity of waste solution in computer spreadsheets. The variability of this simplified approach deviates up to 140% from measured values. Generally, this model can be applied to estimate the conductivity within a factor of two. The comparison of the simplified model to pure component literature data suggests that the simplified model will tend to under estimate the electrical conductivity. Comparison of the computed Tank 40 conductivity with the measured conductivity shows good agreement within the range of deviation identified based on pure component literature data.

  4. Surface electrical conduction due to carrier doping into a surface-state band on Si,,111...-3 3-Ag

    E-print Network

    Hasegawa, Shuji

    Surface electrical conduction due to carrier doping into a surface-state band on Si,,111...- 3 3-Ag into an antibonding surface-state band of this substrate, resulting in a steep increase in electrical conductance through the band. The surface space-charge layer makes no contribution to the conductance increase

  5. Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

    DOEpatents

    Spahn, O.B.; Lear, K.L.

    1998-03-10

    The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g., Al{sub 2}O{sub 3}), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3--1.6 {mu}m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation. 10 figs.

  6. Electrical properties of polypropylene-based composites controlled by multilayered distribution of conductive particles.

    PubMed

    Gao, Wanli; Zheng, Yu; Shen, Jiabin; Guo, Shaoyun

    2015-01-28

    Materials consisting of alternating layers of pure polypropylene (PP) and carbon black filled polypropylene (PPCB) were fabricated in this work. The electrical behaviors of the multilayered composites were investigated from two directions: (1) Parallel to interfaces. The confined layer space allowed for a more compact connection between CB particles, while the conductive pathways tended to be broken up with increasing number of layers leading to a distinct enhancement of the electrical resistivity due to the separation of insulated PP layers. (2) Vertical to interfaces. The alternating assemblies of insulated and conductive layers like a parallel-plate capacitor made the electrical conductivity become frequency dependent. Following the layer multiplication process, the dielectric permittivity was significantly enhanced due to the accumulation of electrical charges at interfaces. Thus, as a microwave was incident on the dielectric medium, the interfacial polarization made the main contribution to inherent dissipation of microwave energy, so that the absorbing peak became strengthened when the material had more layers. Furthermore, the layer interfaces in the multilayered system were also effective to inhibit the propagation of cracks in the stretching process, leading to a larger elongation at the break than that of the PP/CB conventional system, which provided a potential route to fabricate electrical materials with optimal mechanical properties. PMID:25549245

  7. Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

    DOEpatents

    Spahn, Olga B. (Albuquerque, NM); Lear, Kevin L. (Albuquerque, NM)

    1998-01-01

    A semiconductor structure. The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g. Al.sub.2 O.sub.3), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3-1.6 .mu.m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation.

  8. Electrical Conductance Map for the Kachchh Rift Basin: Constraint on Tectonic Evolution and Seismotectonic Implications

    NASA Astrophysics Data System (ADS)

    Subba Rao, P. B. V.; Arora, B. R.; Singh, A. K.

    2014-09-01

    Geomagnetic field variations recorded by an array of magnetometers spread across the Kachchh Rift basin are reduced to a set of induction arrows as a diagnostic of lateral electrical conductivity variations. A non-uniform thin-sheet electrical conductance model is developed to account for the salient induction patterns. It indicates that the imaged conductivity anomalies can be related to the sediment-filled structural lows in between the fault bounded uplifts. It is suggested that sagging structural lows preserved the marine sediments deposited during the Mesozoic sea transgression and later developed into first order embayment basins for the deposition of sediments in association with Late Eocene transgression. Depth integrated electrical conductance helped in mapping two depo-centres: along the ENE-WSW trending Banni half-Graben bounded by the Kachchh Main fault on the south and, second, along the Vinjan depression formed in response to the subsidence between the Vigodi fault and westward extension of the Katrol Hill fault together with the westward bending of the Median High. Presence of metamorphosed graphite schist clasts in shale dominated Mesozoic sequence and/or thin films of carbon resulting from the thermal influence of Deccan activity on Carbonate-rich formations can account for the high electrical conductivity anomalies seen in the depo-centres of thick Mesozoic and Tertiary sediments. Additionally two high conductivity zones are imaged encompassing a block defined by the 2001 Bhuj earthquake and its aftershocks. In agreement with gravity, magnetic and seismic velocity signatures, aqueous fluids released by recrystallizing magmatic bodies intruded in association with Deccan trap activity account for mapped high conductivity zones. High fluid pressure in such a fractured domain, surrounding the intruded magmatic plugs, perturb the regional stress concentrations to produce frequent and low magnitude aftershocks in the shallow section of the epicentral track of the 2001 Bhuj earthquake.

  9. A deterministic model for the growth of non-conducting electrical tree structures

    NASA Astrophysics Data System (ADS)

    Dodd, S. J.

    2003-01-01

    Electrical treeing is of interest to the electrical generation, transmission and distribution industries as it is one of the causes of insulation failure in electrical machines, switchgear and transformer bushings. In this paper a deterministic electrical tree growth model is described. The model is based on electrostatics and local electron avalanches to model partial discharge activity within the growing tree structure. Damage to the resin surrounding the tree structure is dependent on the local electrostatic energy dissipation by partial discharges within the tree structure and weighted by the magnitudes of the local electric fields in the resin surrounding the tree structure. The model is successful in simulating the formation of branched structures without the need of a random variable, a requirement of previous stochastic models. Instability in the spatial development of partial discharges within the tree structure takes the role of the stochastic element as used in previous models to produce branched tree structures. The simulated electrical trees conform to the experimentally observed behaviour; tree length versus time and electrical tree growth rate as a function of applied voltage for non-conducting electrical trees. The phase synchronous partial discharge activity and the spatial distribution of emitted light from the tree structure are also in agreement with experimental data for non-conducting trees as grown in a flexible epoxy resin and in polyethylene. The fact that similar tree growth behaviour is found using pure amorphous (epoxy resin) and semicrystalline (polyethylene) materials demonstrate that neither annealed or quenched noise, representing material inhomogeneity, is required for the formation of irregular branched structures (electrical trees). Instead, as shown in this paper, branched growth can occur due to the instability of individual discharges within the tree structure.

  10. Electrical conductivity of cellular Si/SiC ceramic composites prepared from plant precursors

    SciTech Connect

    Mallick, Debopriyo; Chakrabarti, Omprakash; Bhattacharya, Dipten; Mukherjee, Manabendra; Maiti, Himadri S.; Majumdar, Rabindranath

    2007-02-01

    Electrical conductivity ({sigma}{sub dc}) of the cellular Si/SiC ceramic composites has been measured over a temperature range of 25-1073 K, while the thermoelectric power (S) has been measured over 25-300 K. Remarkably, these cellular compounds developed through the biomimetic route--where the ceramic system grows within a plant biotemplate retaining the imprint of structural intricacies of the native templates--are found to exhibit excellent mechanical, thermal, and electrical properties quite comparable to or even better than those of the systems prepared through the conventional ceramic route. The electrical conductivity, measured parallel ({sigma}{sub (parallel{sub sign})}) and perpendicular ({sigma}{sub (perpendicular{sub sign})}) to the growth axes of the native plants, depicts nearly temperature-independent anisotropy ({sigma}{sub (perpendicular{sub sign})})/{sigma}{sub (parallel{sub sign})}) of the order {approx}2, while the thermoelectric power is nearly isotropic. The charge conduction across the entire temperature regime is found to follow closely the variable range hopping mechanism. The conductivity anisotropy appears to be driven primarily by the unique microcellular morphology of the biotemplates, which can be exploited in many electrical applications.

  11. How Well Does Zone Sampling Based On Soil Electrical Conductivity Maps Represent Soil Variability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Zone soil sampling is a method in which a field sampling is based on identifying homogenous areas using an easy to measure ancillary attribute such as apparent soil electrical conductivity (ECa). This study determined if ECa-directed zone sampling in two fields in northeastern Colorado could correc...

  12. Electric Conduction in Semiconductors: A Pedagogical Model Based on the Monte Carlo Method

    ERIC Educational Resources Information Center

    Capizzo, M. C.; Sperandeo-Mineo, R. M.; Zarcone, M.

    2008-01-01

    We present a pedagogic approach aimed at modelling electric conduction in semiconductors in order to describe and explain some macroscopic properties, such as the characteristic behaviour of resistance as a function of temperature. A simple model of the band structure is adopted for the generation of electron-hole pairs as well as for the carrier…

  13. Relationship between cotton yield and soil electrical conductivity, topography, and landsat imagery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding spatial and temporal variability in crop yield is a prerequisite to implementing site-specific management of crop inputs. Apparent soil electrical conductivity (ECa), soil brightness, and topography are easily obtained data that can explain yield variability. The objectives of this stu...

  14. Inversion of Electrical Conductivity Parameters in Double-Layered Earth with 3-Dimensional Anomalies

    E-print Network

    Inversion of Electrical Conductivity Parameters in Double-Layered Earth with 3-Dimensional of limited size. The geoelectricity study we present here targets double-layered earth structures with three-dimensional anomalies. Scattering and superposition methods are used to deduce a two-layer Dyadic Green's function

  15. PREDOMINANT PROPERTIES AFFECTING PROFILE SOIL ELECTRICAL CONDUCTIVITY IN THE US MIDWEST

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Commercially available sensors for measuring apparent profile soil electrical conductivity (ECa) can provide an indirect indication of a number of soil physical and chemical properties helpful in characterizing within-field variability for precision agriculture. The objective of this research was to...

  16. Seismic reflections and electrical conductivity: A case of Holmes's curious dog?

    E-print Network

    Jones, Alan G.

    Seismic reflections and electrical conductivity: A case of Holmes's curious dog? Frederick A. Cook point to which you wish to draw my attention?'' ``To the curious incident of the dog in the night time.'' ``The dog did nothing in the night time.'' ``That was the curious incident,'' remarked Sherlock Holmes

  17. 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...

  18. Comparison of electrical and thermal conductivities for soils from five states

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arrangement of soil particles, particle size, mineralogy, solute concentration, and bulk density affect electrical (EC) and thermal (TC) conductivities. The purpose of this study was to compare how EC and TC change as a function of water content, for soils under different vegetation and with differe...

  19. Density, Electrical Conductivity and Viscosity of Hg(0.8)Cd(0.2)Te Melt

    NASA Technical Reports Server (NTRS)

    Li, C.; Scripa, R. N.; Ban, H.; Su, C.-H.; Lehoczky, S. L.

    2004-01-01

    The density, viscosity, and electrical conductivity of Hg(0.8)Cd(0.2)Te melt were measured as a function of temperature. A pycnometric method was used to measure the melt density in the temperature range of 1072 to 1122 K. The viscosity and electrical conductivity were determined using a transient torque method from 1068 to 1132 K. The density result from this study is within 0.3% of the published data. However, the current viscosity result is approximately 30% lower than the existing data. The electrical conductivity of Hg(0.8)Cd(0.2)Te melt as a function of temperature, which is not available in the literature, is also determined. The analysis of the temperature dependent electrical conductivity and the relationship between the kinematic viscosity and density indicated that the structure of the melt appeared to be homogeneous when the temperature was above 1090 K. A structural transition occurred in the Hg(0.8)Cd(0.2)Te melt as the temperature was decreased to below 1090 K

  20. 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...

  1. Influence of hydrogen on the electronic states of olivine: Implications for electrical conductivity

    E-print Network

    Influence of hydrogen on the electronic states of olivine: Implications for electrical conductivity; accepted 29 February 2012; published 28 March 2012. [1] The influence of hydrogen on the electronic states of electrons. We find that the dissolution of hydrogen modifies the electronic states when hydrogen

  2. Electrical Conductivity of Molten ZnCl2 at Temperature as High as 1421 K

    NASA Astrophysics Data System (ADS)

    Salyulev, Alexander B.; Potapov, Alexei M.

    2015-02-01

    The electrical conductivity of molten ZnCl2 was measured in a wide temperature range (?T=863 K) to a temperature as high as 1421 K that is 417 degrees above the boiling point of the salt. At the temperature maximum of the own vapor pressure of the salt reached several megapascals.

  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. Estimating spatial variations in water content of clay soils from time-lapse electrical conductivity surveys

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil water content (theta) is one of the most important drivers for many biogeochemical fluxes at different temporal and spatial scales. Hydrogeophysical non-invasive sensors that measure the soil apparent electrical conductivity (ECa) have been widely used to infer spatial and temporal patterns of...

  5. Determination of water saturation using gas phase partitioning tracers and time-lapse electrical conductivity measurements

    SciTech Connect

    Johnson, Timothy C.; Oostrom, Martinus; Truex, Michael J.; Thomle, Jonathan N.; Wietsma, Thomas W.

    2013-05-01

    Water saturation is an important indicator of contaminant distribution and plays a governing role in contaminant transport within the vadose zone. Understanding the water saturation distribution is critical for both remediation and contaminant flux monitoring in unsaturated environments. In this work we propose and demonstrate a method of remotely determining water saturation levels using gas phase partitioning tracers and time-lapse bulk electrical conductivity measurements. The theoretical development includes the partitioning chemistry for the tracers we demonstrate (ammonia and carbon dioxide), as well as a review of the petrophysical relationship governing how these tracers influence bulk conductivity. We also investigate methods of utilizing secondary information provided by electrical conductivity breakthrough magnitudes induced by the tracers. We test the method on clean, well characterized, intermediate-scale sand columns under controlled conditions. Results demonstrate the capability to predict partitioning coefficients and accurately monitor gas breakthrough curves along the length of the column according to the corresponding electrical conductivity response, leading to accurate water saturation estimates. This work is motivated by the need to develop effective characterization and monitoring techniques for contaminated deep vadose zone environments, and provides a proof-of-concept toward uniquely characterizing and monitoring water saturation levels at the field scale and in three-dimensions using electrical resistivity tomography.

  6. Fuel cell components and systems having carbon-containing electrically-conductive hollow fibers

    DOEpatents

    Langry, Kevin C.; Farmer, Joseph C.

    2014-07-08

    According to one embodiment, a system includes a structure having an ionically-conductive, electrically-resistive electrolyte/separator layer covering an inner or outer surface of a carbon-containing electrically-conductive hollow fiber and a catalyst coupled to the hollow fiber, an anode extending along at least part of a length of the structure, and a cathode extending along at least part of the length of the structure, the cathode being on an opposite side of the hollow fiber as the anode. In another embodiment, a method includes acquiring a structure having an ionically-conductive, electrically-resistive electrolyte/separator layer covering an inner or outer surface of a carbon-containing electrically-conductive hollow fiber and a catalyst along one side thereof, adding an anode that extends along at least part of a length of the structure, and adding a cathode that extends along at least part of the length of the structure on an opposite side as the anode.

  7. 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 ...

  8. New down-hole TDR method for deep profile soil water content and bulk electrical conductivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comprehensive irrigation and salinity management both require accurate knowledge of field soil water content and bulk electrical conductivity to depths greater than the root zone depth in agricultural fields. Scientists at the USDA-ARS Conservation & Production Research Laboratory, Bushland, Texas, ...

  9. A Simple Demonstration of the High-Temperature Electrical Conductivity of Glass

    ERIC Educational Resources Information Center

    Chiaverina, Chris

    2014-01-01

    We usually think of glass as a good electrical insulator; this, however, is not always the case. There are several ways to show that glass becomes conducting at high temperatures, but the following approach, devised by Brown University demonstration manager Gerald Zani, may be one of the simplest to perform.

  10. Electrical conductivity of cellular Si /SiC ceramic composites prepared from plant precursors

    NASA Astrophysics Data System (ADS)

    Mallick, Debopriyo; Chakrabarti, Omprakash; Bhattacharya, Dipten; Mukherjee, Manabendra; Maiti, Himadri S.; Majumdar, Rabindranath

    2007-02-01

    Electrical conductivity (?dc) of the cellular Si /SiC ceramic composites has been measured over a temperature range of 25-1073K, while the thermoelectric power (S) has been measured over 25-300K. Remarkably, these cellular compounds developed through the biomimetic route—where the ceramic system grows within a plant biotemplate retaining the imprint of structural intricacies of the native templates—are found to exhibit excellent mechanical, thermal, and electrical properties quite comparable to or even better than those of the systems prepared through the conventional ceramic route. The electrical conductivity, measured parallel (??) and perpendicular (??) to the growth axes of the native plants, depicts nearly temperature-independent anisotropy (??/??) of the order ˜2, while the thermoelectric power is nearly isotropic. The charge conduction across the entire temperature regime is found to follow closely the variable range hopping mechanism. The conductivity anisotropy appears to be driven primarily by the unique microcellular morphology of the biotemplates, which can be exploited in many electrical applications.

  11. REPEATABILITY OF SOIL APPARENT ELECTRICAL CONDUCTIVITY MEASURED BY A COULTER SENSOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Repeatability of a measurement can be assessed by characterizing the variation between successive measurements of the same quantity. Apparent electrical conductivity (ECa) measured using an on-the-go coulter sensor offers advantages for mapping soil variability because detailed data can be colleted ...

  12. Simultaneous Measurement of Viscoelasticity and Electrical Conductivity of an Electrorheological Fluid

    E-print Network

    understood. Assorted polarization models,4-6 a conduction model,7,8 and a water- bridge model9 have been have been made in the past on carbon- black-filled natural rubbers10 or carbon-black-reinforced vulcanizates (in weak dc electric fields 1-3 V/cm)11 to study the effect of carbon black structures inside

  13. Increase of electrical conductivity with pressure as an indicator of conduction through a solid phase in midcrustal rocks

    SciTech Connect

    Shankland, T.J.; Duba, A.G.; Mathez, E.A.; Peach, C.L.

    1997-07-01

    Rocks freshly cored from depth at the German continental scientific drilling site (KTB) offer an opportunity to study transport properties in relatively unaltered samples resembling material in situ. Electrical conductivity {sigma} was measured to 250 MPa pressure, and room temperature on 1 M NaCl-saturated amphibolites from 4 to 5 km depth. An unexpected feature was an increase of {sigma} with pressure P that appeared (anisotropically) in most samples. To characterize this behavior, we fitted the linear portion of log{sigma} versus P to obtain two parameters: the slope d log {sigma}/dP (of order 10{sup {minus}3}MPa{sup {minus}1}) and the zero-pressure intercept {sigma}{sub 0}. Samples of positive and negative slopes behave differently. Those having negative slopes show strong correlation of {sigma}{sub 0} with a fluid property (permeability). This behavior indicates that fluids exert the dominant control on {sigma}{sub 0} at low pressure when {sigma}{sub 0} is greatest, which is typical behavior observed in previous studies. In contrast, samples with positive slopes lack a correlation of {sigma}{sub 0} with permeability, indicating that fluids are less important to positive pressure behavior. Another result is that samples of negative d log {sigma}/dP have uncorrelated slopes and initial conductivities. In significant contrast, samples of positive slopes have the greatest P dependence for lowest initial conductivity {sigma}{sub 0}, that is, the less fluid, the more positive d log {sigma}/dP. Hence positive d log {sigma}/dP is consistent with reconnection of solid phases into a conductive texture better resembling that of rock at depth. Detailed examination of one sample by electron probe and scanning electron microscope reveals the presence of carbon on internal cleavage surfaces in amphibole, the most abundant mineral present. Thus carbon probably dominates the reconnection, but total {sigma} still involves fluids as well as Fe-Ti oxides. (Abstract Truncated)

  14. Electrical conductivity of the quark-gluon plasma across the deconfinement transition.

    PubMed

    Amato, Alessandro; Aarts, Gert; Allton, Chris; Giudice, Pietro; Hands, Simon; Skullerud, Jon-Ivar

    2013-10-25

    A lattice calculation is presented for the electrical conductivity ? of the QCD plasma with 2+1 dynamical flavors at nonzero temperature. We employ the conserved lattice current on anisotropic lattices using a tadpole-improved clover action and study the behavior of the conductivity over a wide range of temperatures, both below and above the deconfining transition. The conductivity is extracted from a spectral-function analysis using the maximal entropy method, and a discussion of its systematics is provided. We find an increase of ?/T across the transition. PMID:24206478

  15. Effect of repetitive laser pulses on the electrical conductivity of intervertebral disc tissue

    SciTech Connect

    Omel'chenko, A I; Sobol', E N

    2009-03-31

    The thermomechanical effect of 1.56-{mu}m fibre laser pulses on intervertebral disc cartilage has been studied using ac conductivity measurements with coaxial electrodes integrated with an optical fibre for laser radiation delivery to the tissue. The observed time dependences of tissue conductivity can be interpreted in terms of hydraulic effects and thermomechanical changes in tissue structure. The laserinduced changes in the electrical parameters of the tissue are shown to correlate with the structural changes, which were visualised using shadowgraph imaging. Local ac conductivity measurements in the bulk of tissue can be used to develop a diagnostic/monitoring system for laser regeneration of intervertebral discs. (laser biology and medicine)

  16. Electrical conductivity of reconstructed Si(111) surface with sodium-doped C60 layers

    NASA Astrophysics Data System (ADS)

    Tsukanov, D. A.; Ryzhkova, M. V.; Borisenko, E. A.; Zotov, A. V.; Saranin, A. A.

    2015-01-01

    Electrical conductance of sodium-doped C60 ultra-thin layers (1-6 monolayers) grown on the Na-adsorbed Si(111)?3 × ?3-Au surface has been studied in situ by four-point probe technique, combined with low-energy electron diffraction observations. Evidence of conductance channel formation through the C60 ultrathin layer is demonstrated as a result of Na dosing of 3 and 6 monolayers thick C60 layers. The observed changes in surface conductivity can be attributed to the formation of fulleride-like NaC60 and Na2C60 compound layers.

  17. Electrical Conductivity of the Quark-Gluon Plasma Across the Deconfinement Transition

    NASA Astrophysics Data System (ADS)

    Amato, Alessandro; Aarts, Gert; Allton, Chris; Giudice, Pietro; Hands, Simon; Skullerud, Jon-Ivar

    2013-10-01

    A lattice calculation is presented for the electrical conductivity ? of the QCD plasma with 2+1 dynamical flavors at nonzero temperature. We employ the conserved lattice current on anisotropic lattices using a tadpole-improved clover action and study the behavior of the conductivity over a wide range of temperatures, both below and above the deconfining transition. The conductivity is extracted from a spectral-function analysis using the maximal entropy method, and a discussion of its systematics is provided. We find an increase of ?/T across the transition.

  18. Holographic electrical and thermal conductivity in strongly coupled gauge theory with multiple chemical potentials

    E-print Network

    Sachin Jain

    2010-04-05

    We study transport coefficients of strongly coupled gauge theory in the presence of multiple chemical potential which are dual to rotating D3, M2 and M5 brane. Using the general form of the perturbation equations, we compute DC-electrical conductivity at finite temperature as well as at zero temperature. We also study thermal conductivity for the same class of black holes and show that thermal conductivity and viscosity obeys Wiedemann-Franz like law even in the presence of multiple chemical potential.

  19. Electric conductive pattern element fabricated using commercial inkjet printer for paper-based analytical devices.

    PubMed

    Matsuda, Yu; Shibayama, Shobu; Uete, Keigo; Yamaguchi, Hiroki; Niimi, Tomohide

    2015-06-01

    Herein, we proposed the addition of an inkjet-printed conductive pattern to paper-based analytical devices (PADs) in order to expand their applications. An electric conductive pattern was easily, quickly, and inexpensively fabricated using a commercial inkjet printer. The addition of a printed electric element will enhance the applications of PADs without the loss of properties such as cost efficiency, disposability, and portability. In this study, we applied an inkjet-printed heater to a piece of paper and investigated its characteristics. The use of the heater as a valve, concentrator, and heat source for chemical reactions on PADs was investigated. Previously, these functions were difficult to realize with PADs. The inkjet-printed heater was used as a valve and concentrator through evaporation of the working fluid and solvent, and was also found to be useful for providing heat for chemical reactions. Thus, the combination of printed electric circuits and PADs has many potential applications. PMID:25952643

  20. Electric conductivity of the quark-gluon plasma investigated using Boltzmann transport theory

    NASA Astrophysics Data System (ADS)

    Greif, Moritz; Bouras, Ioannis; Xu, Zhe; Greiner, Carsten

    2015-05-01

    The electric conductivity of a hot quark-gluon plasma is obtained numerically by solving the relativistic Boltzmann equation. We use a relativistic, semi-classical partonic cascade including screened binary and inelastic, radiative 2 ? 3 perturbative QCD scattering. We employ the Green-Kubo formula and, independently, evaluate the static electric current established by the influence of an external electric field, in order to extract the conductivity. Both numerical methods give the same result. By using only constant, isotropic cross sections, we are able to compare the numerical results and analytic formulas with excellent agreement. Using pQCD scattering with running coupling in the transport code allows us to contrast our results with recent lattice QCD data.

  1. Investigation and modelling of the influence of soil moisture content and soil temperature on apparent electrical conductivity

    NASA Astrophysics Data System (ADS)

    Denk, Astrid; Dietrich, Peter; van der Kruk, Jan; Roth, Kurt; Wollschläger, Ute

    2014-05-01

    Time-lapse shallow ground-based electromagnetic induction (EMI) measurements are often applied to monitor the dynamics of vadose zone soil water content. However, the relationship between the measured apparent electrical conductivity (ECa) and soil water content is not straightforward. First, apparent ECa reflects a depth-weighted value of the ground's electrical conductivity distribution. Linking it directly to a water content value down to a specific depth is therefore not possible. Secondly, the electrical conductivity of the bulk soil depends on the influence of several factors. The major contribution to a change in electrical conductivity is known to be caused by the amount of dissolved ions in the pore fluid, variations in soil water content and soil temperature. In addition, electrical conductivity depends on clay content. There exists no universal petrophysical relationship that relates the sum of all these parameters to electrical conductivity. The separation of the different influences remains challenging since EMI devices are applied in a non-destructive manner and profile information about soil textural properties, soil water content, soil temperature and the soil electrical conductivity is usually not accessible. We use a time series of TDR-measured soil water contents and soil electrical conductivities together with soil temperature data measured at various depths of a soil profile at the Grenzhof test site to investigate the influence of soil water content and temperature on the soil's electrical conductivity. Subsequently, we apply forward modelling of electrical conductivity to estimate the response of the EMI device on temperature-corrected and uncorrected electrical conductivity profiles. Preliminary results show, that the influence of a change in soil water content on apparent electrical conductivity conducts only few mS/m and is often influenced by simultaneous occurring changes in soil temperature.

  2. Development of electrical-erosion instrument for direct write micro-patterning on large area conductive thin films.

    PubMed

    Álvarez, Ángel Luis; Coya, Carmen; García-Vélez, Miguel

    2015-08-01

    We have developed a complete instrument to perform direct, dry, and cost-effective lithography on conductive materials, based on localized electrical discharges, which avoids using masks or chemicals typical of conventional photolithography. The technique is considered fully compatible with substrate transport based systems, like roll-to-roll technology. The prototype is based on two piezo nano-steppers coupled to three linear micro-stages to cover a large scale operation from micrometers to centimeters. The operation mode consists of a spring probe biased at low DC voltage with respect to a grounded conductive layer. The tip slides on the target layer keeping contact with the material in room conditions, allowing continuous electric monitoring of the process, and also real-time tilt correction via software. The sliding tip leaves an insulating path (limited by the tip diameter) along the material, enabling to draw electrically insulated tracks and pads. The physical principle of operation is based in the natural self-limitation of the discharge due to material removal or insulation. The so produced electrical discharges are very fast, in the range of ?s, so features may be performed at speeds of few cm/s, enabling scalability to large areas. The instrument has been tested on different conducting materials as gold, indium tin oxide, and aluminum, allowing the fabrication of alphanumeric displays based on passive matrix of organic light emitting diodes without the use of masks or photoresists. We have verified that the highest potential is achieved on graphene, where no waste material is detected, producing excellent well defined edges. This allows manufacturing graphene micro-ribbons with a high aspect ratio up to 1200:1. PMID:26329218

  3. Development of electrical-erosion instrument for direct write micro-patterning on large area conductive thin films

    NASA Astrophysics Data System (ADS)

    Álvarez, Ángel Luis; Coya, Carmen; García-Vélez, Miguel

    2015-08-01

    We have developed a complete instrument to perform direct, dry, and cost-effective lithography on conductive materials, based on localized electrical discharges, which avoids using masks or chemicals typical of conventional photolithography. The technique is considered fully compatible with substrate transport based systems, like roll-to-roll technology. The prototype is based on two piezo nano-steppers coupled to three linear micro-stages to cover a large scale operation from micrometers to centimeters. The operation mode consists of a spring probe biased at low DC voltage with respect to a grounded conductive layer. The tip slides on the target layer keeping contact with the material in room conditions, allowing continuous electric monitoring of the process, and also real-time tilt correction via software. The sliding tip leaves an insulating path (limited by the tip diameter) along the material, enabling to draw electrically insulated tracks and pads. The physical principle of operation is based in the natural self-limitation of the discharge due to material removal or insulation. The so produced electrical discharges are very fast, in the range of ?s, so features may be performed at speeds of few cm/s, enabling scalability to large areas. The instrument has been tested on different conducting materials as gold, indium tin oxide, and aluminum, allowing the fabrication of alphanumeric displays based on passive matrix of organic light emitting diodes without the use of masks or photoresists. We have verified that the highest potential is achieved on graphene, where no waste material is detected, producing excellent well defined edges. This allows manufacturing graphene micro-ribbons with a high aspect ratio up to 1200:1.

  4. Method for electrically producing dispersions of a nonconductive fluid in a conductive medium

    DOEpatents

    DePaoli, David W. (Knoxville, TN); Tsouris, Constantinos (Oak Ridge, TN); Feng, James Q. (Fairport, NY)

    1998-01-01

    A method for use in electrically forming dispersions of a nonconducting fluid in a conductive medium that minimizes power consumption, gas generation, and sparking between the electrode of the nozzle and the conductive medium. The method utilizes a nozzle having a passageway, the wall of which serves as the nozzle electrode, for the transport of the nonconducting fluid into the conductive medium. A second passageway provides for the transport of a flowing low conductivity buffer fluid which results in a region of the low conductivity buffer fluid immediately adjacent the outlet from the first passageway to create the necessary protection from high current drain and sparking. An electrical potential difference applied between the nozzle electrode and an electrode in contact with the conductive medium causes formation of small droplets or bubbles of the nonconducting fluid within the conductive medium. A preferred embodiment has the first and second passageways arranged in a concentric configuration, with the outlet tip of the first passageway withdrawn into the second passageway.

  5. Optimizing amorphous indium zinc oxide film growth for low residual stress and high electrical conductivity

    NASA Astrophysics Data System (ADS)

    Kumar, Mukesh; Sigdel, A. K.; Gennett, T.; Berry, J. J.; Perkins, J. D.; Ginley, D. S.; Packard, C. E.

    2013-10-01

    With recent advances in flexible electronics, there is a growing need for transparent conductors with optimum conductivity tailored to the application and nearly zero residual stress to ensure mechanical reliability. Within amorphous transparent conducting oxide (TCO) systems, a variety of sputter growth parameters have been shown to separately impact film stress and optoelectronic properties due to the complex nature of the deposition process. We apply a statistical design of experiments (DOE) approach to identify growth parameter-material property relationships in amorphous indium zinc oxide (a-IZO) thin films and observed large, compressive residual stresses in films grown under conditions typically used for the deposition of highly conductive samples. Power, growth pressure, oxygen partial pressure, and RF power ratio (RF/(RF + DC)) were varied according to a full-factorial test matrix and each film was characterized. The resulting regression model and analysis of variance (ANOVA) revealed significant contributions to the residual stress from individual growth parameters as well as interactions of different growth parameters, but no conditions were found within the initial growth space that simultaneously produced low residual stress and high electrical conductivity. Extrapolation of the model results to lower oxygen partial pressures, combined with prior knowledge of conductivity-growth parameter relationships in the IZO system, allowed the selection of two promising growth conditions that were both empirically verified to achieve nearly zero residual stress and electrical conductivities >1480 S/cm. This work shows that a-IZO can be simultaneously optimized for high conductivity and low residual stress.

  6. Method for electrically producing dispersions of a nonconductive fluid in a conductive medium

    DOEpatents

    DePaoli, D.W.; Tsouris, C.; Feng, J.Q.

    1998-06-09

    A method is described for use in electrically forming dispersions of a nonconducting fluid in a conductive medium that minimizes power consumption, gas generation, and sparking between the electrode of the nozzle and the conductive medium. The method utilizes a nozzle having a passageway, the wall of which serves as the nozzle electrode, for the transport of the nonconducting fluid into the conductive medium. A second passageway provides for the transport of a flowing low conductivity buffer fluid which results in a region of the low conductivity buffer fluid immediately adjacent the outlet from the first passageway to create the necessary protection from high current drain and sparking. An electrical potential difference applied between the nozzle electrode and an electrode in contact with the conductive medium causes formation of small droplets or bubbles of the nonconducting fluid within the conductive medium. A preferred embodiment has the first and second passageways arranged in a concentric configuration, with the outlet tip of the first passageway withdrawn into the second passageway. 4 figs.

  7. Electrical and thermal conduction in ultra-thin freestanding atomic layer deposited W nanobridges

    NASA Astrophysics Data System (ADS)

    Eigenfeld, Nathan T.; Gertsch, Jonas C.; Skidmore, George D.; George, Steven M.; Bright, Victor M.

    2015-10-01

    Work presented here measures and interprets the electrical and thermal conductivities of atomic layer deposited (ALD) free-standing single film and periodic tungsten and aluminum oxide nanobridges with thicknesses from ~5-20 nm and ~3-13 nm, respectively. Electrical conductivity of the W films is reduced by up to 99% from bulk, while thermal conductivity is reduced by up to 91%. Results indicate phonon contribution to thermal conductivity is dominant in these ALD films and may be substantially reduced by the incorporation of periodicity in the ALD W/Al2O3 nanolaminates. Additionally, thin film conduction modeling demonstrates nano-structured grain features largely dictate electron and phonon conduction in ALD W. New fabrication methods have allowed for the development of free-standing ultra-thin structures with layers on the order of several nanometers utilizing ALD. While the literature contains diverse studies of the physical properties of thin films prepared by traditional micro-fabrication sputtering or chemical vapor deposition techniques, there remains little data on freestanding structures containing ALD generated materials. Specifically, knowledge of the electrical and thermal conductivity of ALD generated materials will aid in the future development of ultra-thin nano-devices.Work presented here measures and interprets the electrical and thermal conductivities of atomic layer deposited (ALD) free-standing single film and periodic tungsten and aluminum oxide nanobridges with thicknesses from ~5-20 nm and ~3-13 nm, respectively. Electrical conductivity of the W films is reduced by up to 99% from bulk, while thermal conductivity is reduced by up to 91%. Results indicate phonon contribution to thermal conductivity is dominant in these ALD films and may be substantially reduced by the incorporation of periodicity in the ALD W/Al2O3 nanolaminates. Additionally, thin film conduction modeling demonstrates nano-structured grain features largely dictate electron and phonon conduction in ALD W. New fabrication methods have allowed for the development of free-standing ultra-thin structures with layers on the order of several nanometers utilizing ALD. While the literature contains diverse studies of the physical properties of thin films prepared by traditional micro-fabrication sputtering or chemical vapor deposition techniques, there remains little data on freestanding structures containing ALD generated materials. Specifically, knowledge of the electrical and thermal conductivity of ALD generated materials will aid in the future development of ultra-thin nano-devices. Electronic supplementary information (ESI) available: This information outlines examples of thermal conductance measurements, thermal conductivity extraction, accuracy of the measurement method and thermal loss calculations and adjustments. Also, discussion of XRD film analysis and ALD grain size is included. See DOI: 10.1039/c5nr04885k

  8. SIGMELTS: A Web-portal for Electrical Conductivity Calculations in Geosciences

    NASA Astrophysics Data System (ADS)

    Le Trong, E.; Pommier, A.

    2010-12-01

    We present a freely available and easy-to-use web application called SIGMELTS allowing the calculation of the electrical conductivity of geomaterials at relevant conditions for the Earth’s crust and mantle. By compiling previous results of electrical measurements in laboratory, this software enables to discriminate between the effect of different parameters on the bulk conductivity of silicate melts, carbonatites, fluids, minerals and mantle materials, such as the temperature (T), the pressure (P), the composition, the water content, the oxygen fugacity (fO2) and the crystal content. Different existing geometrical models are proposed to calculate the bulk conductivity of a two-phase mixture. Based on the electrical conductivity value of a mantle anomaly, an application has also been developed to determine the corresponding melt fraction at defined conditions (T, P, composition). This web application aims at improving the accessibility to laboratory data in order to precise the interpretation of MT profiles. Although there are examples of where the laboratory data have been used to interpret field data, there are also many instances where there are disconnects between those interpreting field MT data and the laboratory results. SIGMELTS also underlines that new electrical measurements in laboratory are needed to enlarge the present electrical database, particularly at high pressure conditions. An illustration of the use of SIGMELTS will be presented, in which calculations are applied to 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 to quantify their storage conditions.

  9. Thermal and electrical conductivity of defective graphene: From grain boundaries to haeckelite

    NASA Astrophysics Data System (ADS)

    Zhu, Zhen; Fthenakis, Zacharias G.; Tomanek, David

    2014-03-01

    We study the effect of structural defects on the electronic and thermal conductivity of graphene from first-principles calcluations. After optimizing defective structures using density functional theory, we describe ballistic charge transport using the non-equilibrium Green's function formalism and thermal transport using non-equilibrium molecular dynamics simulations. We find that both the electrical conductance G and thermal conductivity ? depend sensitively on the nature, concentration and arrangement of 5-7 and 5-8 defects, which may form grain boundaries in the honeycomb lattice of graphene or, at large concentrations, convert it to haeckelite. Lines of defects in graphene turn both ? and ? anisotropic. In a defective structure of graphene nanoribbons interconnected by haeckelite strips, the electrical conductance G increases, whereas the thermal conductivity is quenched by up to 1-2 orders of magnitude, mainly due to the reduced phonon mean free path. We conclude that defects play a profound role in the electrical and thermal transport of graphene. Supported by the National Science Foundation Cooperative Agreement #EEC-0832785, titled ``NSEC: Center for High-rate Nanomanufacturing.''

  10. LC nanocomposites: induced optical singularities, managed nano/micro structure, and electrical conductivity

    E-print Network

    V. V. Ponevchinsky; A. I. Goncharuk; V. G. Denisenko; N. I. Lebovka; L. N. Lisetski; M. I. Nesterenko; V. D. Panikarskaya; M. S. Soskin

    2013-03-03

    Microstructure, phase transitions, electrical conductivity, and optical and electrooptical properties of multiwalled carbon nanotubes (NTs), dispersed in the cholesteric liquid crystal (cholesteryl oleyl carbonate, COC), nematic 5CB and their mixtures, were studied in the temperature range between 255 K and 363 K. The relative concentration X=COC/(COC+5CB)was varied within 0.0-1.0. The concentration $C_p$ of NTs was varied within 0.01-5% wt. The value of X affected agglomeration and stability of NTs inside COC+5CB. High-quality dispersion, exfoliation, and stabilization of the NTs were observed in COC solvent ("good" solvent). From the other side, the aggregation of NTs was very pronounced in nematic 5CB solvent ("bad" solvent). The dispersing quality of solvent influenced the percolation concentration $C_p$, corresponding to transition between the low conductive and high conductive states: e.g., percolation was observed at $C_p=1%$ and $C_p=0.1%$ for pure COC and 5CB, respectively. The effects of thermal pre-history on the heating-cooling hysteretic behavior of electrical conductivity were studied. The mechanism of dispersion of NTs in COC+5CB mixtures is discussed. Utilization of the mixtures of "good" and "bad" solvents allowed fine regulation of the dispersion, stability and electrical conductivity of LC+NTs composites. The mixtures of COC and 5CB were found to be promising for application as functional media with controllable useful chiral and electrophysical properties.

  11. Electrical Conductivity of H2O-CO2 rich-Melt at mantle conditions: interpretation of the LAB using petrology-based 1D conductivity profiles.

    NASA Astrophysics Data System (ADS)

    Sifre, D.; Gaillard, F.; Hashim, L.; Massuyeau, M.; Gardés, E.; Hier-Majumder, S.

    2014-12-01

    Electromagnetic data images mantle regions more conductive than that of dry olivine. There is no doubt that melt is thermodynamically stable and present in the LAB, but how they can impact on mantle electrical conductivity remains debated. In addition, gravitational segregation and fast melt upwelling, being expected if melt fraction exceeds 2 vol. %, is thought to seriously restrict the role of partial melting at the level of the LAB. Petrological studies realized some 30 years ago have shown that peridotites exposed at the P-T-fO2 conditions of the LAB produced H2O and CO2 rich-melts. The segregation of such melts is not expected since they constitute only about 0.5 vol. % of the peridotite, but electrical conductivities of these melts are poorly known. Therefore, electrical conductivity experiments have been performed in piston cylinder on H2O-CO2 rich melts. Different melt compositions have been explored, from carbonated melts to basalts. The effects of chemical compositions and volatiles on these melts have been determined. The electrical conductivity measurements have shown that hydrous carbonated melts are very conductive, and the incorporation of basalt decreases the conductivity. With these new data, a semi-empirical law predicting the conductivity as a function of H2O and CO2 contents has been produced. Based on this law and the electrical conductivity of olivine, 1D conductivity profiles were constructed. With these profiles, the effect of volatiles content (partitioned between the melt and in the solids), melt fractions (mixing law and interconnection of the melt) and different temperature regimes on conductivity are discussed. These calculations are conducted on oceanic and continental settings with different ages. The electrical conductivities of the mantle is thus a powerful tool to track the fundamental process of mantle incipient melting, which is in turn narrowly associated to the cycling of H2O and CO2 in the upper mantle.

  12. Influence of natural time-dependent variations of electrical conductivity on DC resistivity measurements

    NASA Astrophysics Data System (ADS)

    Rein, Arno; Hoffmann, Ruth; Dietrich, Peter

    2004-01-01

    Long-term direct current (DC) resistivity monitoring surveys are carried out to investigate structures and processes in the subsurface which are coupled to changes in electrical conductivity. Examples would be leaching tests in the unsaturated zone or the observation of a salt tracer spreading in the saturated zone. As these investigations usually take some hours to weeks, natural time-dependent background variations of electrical conductivity have to be considered. Parameters influencing the electrical conductivity are temperature changes, variable water contents in soil due to precipitation or changing groundwater levels, and natural fluctuations of the ionar content in groundwater. Measurements over different time periods (one month to one year) at different test sites demonstrated daily and seasonal trends of electrical conductivity and temperature of groundwater, surface temperatures and groundwater levels. Variable water saturation and changing soil temperatures (in the uppermost soil) are estimated to influence the electrical conductivity most significantly, followed by changing water temperatures and varying ionar content. To verify these conclusions, multi-electrode DC resistivity monitoring has been performed at two test sites for 16 and 22 days. The results reflect natural characteristics and processes in the subsurface. With mean values and standard deviations of apparent resistivities plotted in pseudosections, different areas of the subsurface with different ranges of resistivity variations have been specified. In the area of variable groundwater level (varying water saturation) and in the uppermost soil (strong temperature and moisture changes), especially high resistivity variations are obvious (up to 26%). In the saturated zone, variations are low (predominately below 1%). Concerning resistivity measurements, we conclude that electrodes positioned below the groundwater level (e.g. for salt tracer tests) or between the uppermost meter of subsurface and the area of variable groundwater level (e.g. for leaching tests in the unsaturated zone) should be used to avoid strong influences of background variations.

  13. Electrical conductivity measurements of aqueous fluids under pressure with a hydrothermal diamond anvil cell.

    PubMed

    Ni, Huaiwei; Chen, Qi; Keppler, Hans

    2014-11-01

    Electrical conductivity data of aqueous fluids under pressure can be used to derive the dissociation constants of electrolytes, to assess the effect of ionic dissociation on mineral solubility, and to interpret magnetotelluric data of earth's interior where a free fluid phase is present. Due to limitation on the tensile strength of the alloy material of hydrothermal autoclaves, previous measurements of fluid conductivity were mostly restricted to less than 0.4 GPa and 800?°C. By adapting a Bassett-type hydrothermal diamond anvil cell, we have developed a new method for acquiring electrical conductivity of aqueous fluids under pressure. Our preliminary results for KCl solutions using the new method are consistent with literature data acquired with the conventional method, but the new method has great potential for working in a much broader pressure range. PMID:25430149

  14. Electrical conductivity of hollow polyaniline microspheres synthesized by a self-assembly method

    NASA Astrophysics Data System (ADS)

    Long, Yunze; Chen, Zhaojia; Ma, Yongjun; Zhang, Ze; Jin, Aizi; Gu, Changzhi; Zhang, Lijuan; Wei, Zhixiang; Wan, Meixiang

    2004-03-01

    In this letter, we report the electrical properties of hollow polyaniline (PANI) microspheres. ?-naphthalene sulfonic acid (NSA) and salicylic acid (SA) doped PANI microspheres were synthesized by a self-assembly method. The room-temperature conductivity is 8.6×10-2 S/cm for PANI-NSA microspheres (0.8-2 ?m in outer diameter) and 5.6×10-4 S/cm for PANI-SA microspheres (3-7 ?m in outer diameter). The conductivity of an individual PANI-SA microsphere is measured directly by a two-probe technique, about 8×10-2 S/cm (which is two orders of magnitude higher than that of a PANI-SA microsphere's pellet). The measurements of conductivity, I-V curve, and magnetoresistance demonstrate that the electrical properties of PANI microspheres are dominated by the intersphere contacts due to the sample's microscopic inhomogeneity.

  15. Exploiting redox chemistries to manipulate structure and electrical conductivity in polymer acid-doped polyaniline

    NASA Astrophysics Data System (ADS)

    Tarver, Jacob; Fan, Joline; Loo, Yueh-Lin

    2011-03-01

    Template synthesis of polyaniline on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) yields electrostatically stabilized particles that can be aqueously dispersed and cast into thin films; electrical conductivity in these films scales with inter-particle connectivity. Previous research has shown that solvent annealing with dichloroacetic acid (DCA) induces structural rearrangement of polymer chains and consequently enhances the electrical conductivity by up to two orders of magnitude (from 0.4 to 40 S/cm). Alternatively, the electrostatic interactions between polyaniline and its template can be neutralized through chemical reduction with hydrazine monohydrate, after which the polymer undergoes extensive structural rearrangement; subsequent exposure to nitric oxide leads to reassociation of polyaniline and its polymer acid dopant. Enhanced conductivity is observed following this chemical redox process, and is attributed to extensive polymer chain relaxation and concurrent elimination of the particulate nature of template-synthesized polyaniline.

  16. Electrical conductivity of the Earth's mantle from the first Swarm magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Civet, F.; Thébault, E.; Verhoeven, O.; Langlais, B.; Saturnino, D.

    2015-05-01

    We present a 1-D electrical conductivity profile of the Earth's mantle down to 2000 km derived from L1b Swarm satellite magnetic field measurements from November 2013 to September 2014. We first derive a model for the main magnetic field, correct the data for a lithospheric field model, and additionally select the data to reduce the contributions of the ionospheric field. We then model the primary and induced magnetospheric fields for periods between 2 and 256 days and perform a Bayesian inversion to obtain the probability density function for the electrical conductivity as function of depth. The conductivity increases by 3 orders of magnitude in the 400-900 km depth range. Assuming a pyrolitic mantle composition, this profile is interpreted in terms of temperature variations leading to a temperature gradient in the lower mantle that is close to adiabatic.

  17. A review of properties and potential aerospace applications of electrically conducting polymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Gaier, James R.; Good, Brian S.; Sharp, G. Richard; Meador, Michael A.

    1990-01-01

    An overview of current research in conducting polymers is presented. Emphasis is placed on development of materials useful for aeronautic and space applications. Research on organic conducting polymers began in the early 1970s with the discovery of polyacetylene. Since then, many polymers which share structural characteristics with polyacetylene have been prepared which conduct electricity, especially when they are doped with suitable agents. Problems with environmental instability, difficult processing, poor mechanical properties and high cost have slowed the development of conducting polymers. However, practical use of these materials is imminent, based on recent refinements in understanding how polymers conduct, more systematic approaches to the development of new materials, and significant improvements in both the processing and properties.

  18. A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors

    PubMed Central

    Huang, Jian; Wang, Zhiwei; Zhang, Junyao; Zhang, Xingran; Ma, Jinxing; Wu, Zhichao

    2015-01-01

    Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2?V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs. PMID:25784160

  19. Influence of Frequency and Temperature on the Mechanisms of Nerve Conduction Block Induced by High-Frequency Biphasic Electrical Current

    PubMed Central

    Wang, Jicheng; Shen, Bing; Roppolo, James R.; de Groat, William C.; Tai, Changfeng

    2010-01-01

    The influences of stimulation frequency and temperature on mechanisms of nerve conduction block induced by high-frequency biphasic electrical current were investigated using a lumped circuit model of the myelinated axon based on Schwarz and Eikhof (SE) equations. The simulation analysis showed that a temperature-frequency relationship was determined by the axonal membrane dynamics (i.e. how fast the ion channels can open or close.). At a certain temperature, the axonal conduction block always occurred when the period of biphasic stimulation was smaller than the action potential duration (APD). When the temperature decreased from 37°C to 15°C, the membrane dynamics slowed down resulting in an APD increase from 0.4 ms to 2.4 ms accompanied by a decrease in the minimal blocking frequency from 4 kHz to 0.5 kHz. The simulation results also indicated that as the stimulation frequency increased the mechanism of conduction block changed from a cathodal/anodal block to a block dependent upon continuous activation of potassium channels. Understanding the interaction between the minimal blocking frequency and temperature could promote a better understanding of the mechanisms of high frequency induced axonal conduction block and the clinical application of this method for blocking the nerve conduction. PMID:17682929

  20. Characterizing the spatial variability of soil infiltration using apparent electrical conductivity

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  1. The application of electrical conductivity as a tracer for hydrograph separation in urban catchments

    USGS Publications Warehouse

    Pellerin, B.A.; Wollheim, W.M.; Feng, X.; Vororsmarty, C.J.

    2008-01-01

    Two-component hydrograph separation was performed on 19 low-to-moderate intensity rainfall events in a 4.1-km2 urban watershed to infer the relative and absolute contribution of surface runoff (e.g. new water) to stormflow generation between 2001 and 2003. The electrical conductivity (EC) of water was used as a continuous and inexpensive tracer, with order of magnitude differences in precipitation (12-46 ??S/cm) and pre-event streamwater EC values (520-1297 ??S/cm). While new water accounted for most of the increased discharge during storms (61-117%), the contribution of new water to total discharge during events was typically lower (18-78%) and negatively correlated with antecedent stream discharge (r2 = 0??55, p < 0??01). The amount of new water was positively correlated with total rainfall (r2 = 0??77), but hydrograph separation results suggest that less than half (9-46%) of the total rainfall on impervious surfaces is rapidly routed to the stream channel as new water. Comparison of hydrograph separation results using non-conservative tracers (EC and Si) and a conservative isotopic tracer (??D) for two events showed similar results and highlighted the potential application of EC as an inexpensive, high frequency tracer for hydrograph separation studies in urban catchments. The use of a simple tracer-based approach may help hydrologists and watershed managers to better understand impervious surface runoff, stormflow generation and non-point-source pollutant loading to urban streams. Copyright ?? 2007 John Wiley & Sons, Ltd.

  2. Dosimeter-Type NOx Sensing Properties of KMnO4 and Its Electrical Conductivity during Temperature Programmed Desorption

    PubMed Central

    Gro?, Andrea; Kremling, Michael; Marr, Isabella; Kubinski, David J.; Visser, Jacobus H.; Tuller, Harry L.; Moos, Ralf

    2013-01-01

    An impedimetric NOx dosimeter based on the NOx sorption material KMnO4 is proposed. In addition to its application as a low level NOx dosimeter, KMnO4 shows potential as a precious metal free lean NOx trap material (LNT) for NOx storage catalysts (NSC) enabling electrical in-situ diagnostics. With this dosimeter, low levels of NO and NO2 exposure can be detected electrically as instantaneous values at 380 °C by progressive NOx accumulation in the KMnO4 based sensitive layer. The linear NOx sensing characteristics are recovered periodically by heating to 650 °C or switching to rich atmospheres. Further insight into the NOx sorption-dependent conductivity of the KMnO4-based material is obtained by the novel eTPD method that combines electrical characterization with classical temperature programmed desorption (TPD). The NOx loading amount increases proportionally to the NOx exposure time at sorption temperature. The cumulated NOx exposure, as well as the corresponding NOx loading state, can be detected linearly by electrical means in two modes: (1) time-continuously during the sorption interval including NOx concentration information from the signal derivative or (2) during the short-term thermal NOx release. PMID:23549366

  3. On the specifics of the electrical conductivity anomalies in PVC nanocomposites

    E-print Network

    D. V. Vlasov; L. A. Apresyan

    2013-02-25

    A qualitative model describing the "anomalous" features of the conductivity of polymer nanocomposites, in particular, switching to the conducting state in relatively thick (tens of microns or more) of flexible PVC films is considered. In previously published experimental results, change of conductivity by 10 or more orders of magnitude occurred both in the absence of external influences (spontaneously), and under the influence of an applied electric field, as well as other initiating factors (such as uniaxial pressure) . In a model of hopping conduction mechanism it is shown, that switching in the conduction states under the action of external field significantly (by orders of magnitude) below threshold can be associated with a high-resistance state instability that results from the sequence of "shorting" (reversible soft breakdown) of narrow insulating gaps between regions with relatively high conductivity. Increasing the field strength in the remaining insulating gaps ultimately leads to the formation of a conducting channel between the external electrodes and switching conductivity of the composite film sample in a state of high conductivity. This cascade model is essentially based on the transition from the usual description of the charge tunneling through single independent insulating gap to take into account correlations between adjacent gaps. In the frame of developed model other "anomalies" such as exponential dependence of the resistance on the sample thickness, pressure, and other influences can be qualitative explained. An analogy of the model with a cascading breakdown of avalanche transistors is also considered.

  4. Spectroscopic determination of electrical conductivity in an MHD duct from absolute intensity measurements

    NASA Technical Reports Server (NTRS)

    Wang, S. Y.; Smith, M.

    1977-01-01

    Measurements of the electrical conductivity in the NASA Lewis cesium seeded, H2-O2 MHD duct have been previously reported. In order to corroborate the above measurements and to analyze the possibility of nonuniform seed injection as a cause of the deviations, a spectroscopic investigation of the plasma conductivity has been undertaken. Transverse profiles of the absolute integrated intensity were measured from the optically thin lines of CSI-.5664 microns and .5636 microns. Radial profiles of emission coefficient were obtained from the measured transverse profiles of intensity by Abel inversion. Radial profiles of electrical conductivity were then obtained under two different assumptions. In the first, the Cs seed fraction is assumed uniform and equal to the measured flow rate at the time when the temperature and conductivity were obtained. In the second method, the local temperature and pressure are taken to be those given by a one-dimensional channel calculation including heat transfer and friction. In this case profiles of conductivity and seed fractions are obtained. The results of the two methods are compared to the previously measured conductivity.

  5. The electrical conductivity of Al2O3 under shock-compression

    PubMed Central

    Liu, Hanyu; Tse, John S.; Nellis, W. J.

    2015-01-01

    Sapphire (Al2O3) crystals are used below 100?GPa as anvils and windows in dynamic-compression experiments because of their transparency and high density. Above 100?GPa shock pressures, sapphire becomes opaque and electrically conducting because of shock-induced defects. Such effects prevent temperature and dc conductivity measurements of materials compressed quasi-isentropically. Opacities and electrical conductivities at ~100?GPa are non-equilibrium, rather than thermodynamic parameters. We have performed electronic structure calculations as a guide in predicting and interpreting shock experiments and possibly to discover a window up to ~200?GPa. Our calculations indicate shocked sapphire does not metallize by band overlap at ~300?GPa, as suggested previously by measured non-equilibrium data. Shock-compressed Al2O3 melts to a metallic liquid at ~500?GPa and 10,000?K and its conductivity increases rapidly to ~2000???1cm?1 at ~900?GPa. At these high shock temperatures and pressures sapphire is in thermal equilibrium. Calculated conductivity of Al2O3 is similar to those measured for metallic fluid H, N, O, Rb, and Cs. Despite different materials, pressures and temperatures, and compression techniques, both experimental and theoretical, conductivities of all these poor metals reach a common end state typical of strong-scattering disordered materials. PMID:26239369

  6. The electrical conductivity of Al2O3 under shock-compression

    NASA Astrophysics Data System (ADS)

    Liu, Hanyu; Tse, John S.; Nellis, W. J.

    2015-08-01

    Sapphire (Al2O3) crystals are used below 100?GPa as anvils and windows in dynamic-compression experiments because of their transparency and high density. Above 100?GPa shock pressures, sapphire becomes opaque and electrically conducting because of shock-induced defects. Such effects prevent temperature and dc conductivity measurements of materials compressed quasi-isentropically. Opacities and electrical conductivities at ~100?GPa are non-equilibrium, rather than thermodynamic parameters. We have performed electronic structure calculations as a guide in predicting and interpreting shock experiments and possibly to discover a window up to ~200?GPa. Our calculations indicate shocked sapphire does not metallize by band overlap at ~300?GPa, as suggested previously by measured non-equilibrium data. Shock-compressed Al2O3 melts to a metallic liquid at ~500?GPa and 10,000?K and its conductivity increases rapidly to ~2000??-1cm-1 at ~900?GPa. At these high shock temperatures and pressures sapphire is in thermal equilibrium. Calculated conductivity of Al2O3 is similar to those measured for metallic fluid H, N, O, Rb, and Cs. Despite different materials, pressures and temperatures, and compression techniques, both experimental and theoretical, conductivities of all these poor metals reach a common end state typical of strong-scattering disordered materials.

  7. A Study of the Preparation and Properties of Antioxidative Copper Inks with High Electrical Conductivity.

    PubMed

    Tsai, Chia-Yang; Chang, Wei-Chen; Chen, Guan-Lin; Chung, Cheng-Huan; Liang, Jun-Xiang; Ma, Wei-Yang; Yang, Tsun-Neng

    2015-12-01

    Conductive ink using copper nanoparticles has attracted much attention in the printed electronics industry because of its low cost and high electrical conductivity. However, the problem of easy oxidation under heat and humidity conditions for copper material limits the wide applications. In this study, antioxidative copper inks were prepared by dispersing the nanoparticles in the solution, and then conductive copper films can be obtained after calcining the copper ink at 250 °C in nitrogen atmosphere for 30 min. A low sheet resistance of 47.6 m?/? for the copper film was measured by using the four-point probe method. Importantly, we experimentally demonstrate that the electrical conductivity of copper films can be improved by increasing the calcination temperature. In addition, these highly conductive copper films can be placed in an atmospheric environment for more than 6 months without the oxidation phenomenon, which was verified by energy-dispersive X-ray spectroscopy (EDS). These observations strongly show that our conductive copper ink features high antioxidant properties and long-term stability and has a great potential for many printed electronics applications, such as flexible display systems, sensors, photovoltaic cells, and radio frequency identification. PMID:26370132

  8. Sensing of electrically conductive textiles and capacitance sensor-embedded fabrics for parachutes

    NASA Astrophysics Data System (ADS)

    Damplo, Mark; Niezrecki, Christopher; Willis, David; Chen, Julie; Niemi, Eugene; Agnihotra, Srikanthrao; Manohar, Sanjeev K.; Desabrais, Kenneth; Charette, Christine

    2012-04-01

    This paper evaluates the conductive properties and sensing capabilities of various smart materials being considered for enhancing parachute performance. In a previous review of sensing technologies, several materials showed potential for parachute implementation - specifically, electrically conductive textiles and dielectric electro-active polymers (DEAPs). Past efforts have been focused on mechanically testing and evaluating the sensing performance of conductive fabrics (coated with carbon nanotubes, polypyrrole and polyaniline) and DEAPs. While some of the conductive fabrics demonstrated sufficient sensing capability, they were not conductive enough to implement into an intelligent parachute sensor network for transmitting power or data. Also, attaching or stitching DEAPs to the parachute fabric has proven to be a challenge. The primary goal of this paper is to investigate the use of highly-conductive textiles in an intelligent textile sensor network for sensing and as a means to transmit power or electrical signals. The applications of the materials investigated in this paper may also extend beyond parachutes to any large-scale textile structure.

  9. The electrical conductivity of Al2O3 under shock-compression.

    PubMed

    Liu, Hanyu; Tse, John S; Nellis, W J

    2015-01-01

    Sapphire (Al2O3) crystals are used below 100 GPa as anvils and windows in dynamic-compression experiments because of their transparency and high density. Above 100 GPa shock pressures, sapphire becomes opaque and electrically conducting because of shock-induced defects. Such effects prevent temperature and dc conductivity measurements of materials compressed quasi-isentropically. Opacities and electrical conductivities at ~100 GPa are non-equilibrium, rather than thermodynamic parameters. We have performed electronic structure calculations as a guide in predicting and interpreting shock experiments and possibly to discover a window up to ~200 GPa. Our calculations indicate shocked sapphire does not metallize by band overlap at ~300 GPa, as suggested previously by measured non-equilibrium data. Shock-compressed Al2O3 melts to a metallic liquid at ~500 GPa and 10,000 K and its conductivity increases rapidly to ~2000 ?(-1)cm(-1) at ~900 GPa. At these high shock temperatures and pressures sapphire is in thermal equilibrium. Calculated conductivity of Al2O3 is similar to those measured for metallic fluid H, N, O, Rb, and Cs. Despite different materials, pressures and temperatures, and compression techniques, both experimental and theoretical, conductivities of all these poor metals reach a common end state typical of strong-scattering disordered materials. PMID:26239369

  10. Electrical and Thermal Conductivity of Liquid Iron at Core Pressures and Temperatures: First-Principles Calculations

    NASA Astrophysics Data System (ADS)

    de Koker, N.; Steinle-Neumann, G.; Vl?ek, V.

    2010-12-01

    The ability of liquid iron to transport heat and electric charge by conduction at extreme pressure and temperature is of paramount importance to the thermal history of the core. Thermal conductivity determines the amount of heat conducted along the core adiabat, i.e. heat not available for generation of the magnetic field, and also strongly controls the time required for the inner core to reach its current size. Electrical conductivity sets the rate of magnetic field dissipation, and consequently the amount of energy required to sustain the geodynamo. Also, because these properties tightly control the heat budget within the core, they dictate the extent to which radiogenic heat need to be invoked to obtain thermal history models that are in agreement with geophysical and paleomagnetic observations. Current estimates for electrical conductivity of iron at conditions characteristic of Earth's core are rather uncertain, constraining the value only to within a factor of three. Thermal conductivity values are subsequently obtained by applying the Wiedemann-Franz relation, the validity of which has not been rigorously shown at extreme pressures. In addition, electronic transport properties are expected to depend strongly on pressure (P) and temperature (T), as well as on the concentration (X) of light elements in the liquid metal. However, with no data available on these variations, geophysical studies in which these values are applied invariably assume them to be constant. In an effort to improve our understanding of the P-T-X behavior of electronic transport properties in the core, and also to test the various assumptions made in their determination, we have performed first-principles calculations of the electrical and thermal conductivity of liquid iron over a large range of pressure and temperature conditions, including those characteristic of Earth's core. Compositions respectively doped with silicon, oxygen and sulphur are also considered. These calculations involve using first-principles molecular dynamics to generate a series of uncorrelated liquid structures at constant temperature and density, for which the electronic transport properties are then computed using the Kubo-Greenwood equation. Our aim is to construct a parameterized model for the thermal and electrical conductivity of liquid iron as a function of pressure, temperature and light element composition, which can be applied in geodynamo simulations and thermal history models for planetary cores. Preliminary results indicate a strong pressure and temperature dependence, with the Wiedemann-Franz relation only approximately satisfied. Implications of these results for models of the thermal history of the core will be considered and discussed.

  11. Electrical conduction mechanisms and dielectric constants of nanostructured methyl violet 2B thin films

    NASA Astrophysics Data System (ADS)

    Zeyada, H. M.; Makhlouf, M. M.

    2015-06-01

    The uniform thin films of methyl violet 2B, MV2B, with thicknesses ranged from 96 to 300 nm, have been successfully prepared by spin coating technique. X-ray diffraction showed that the powder and pristine thin film of MV2B have amorphous structure. The amorphous pristine films become polymorphous nanocrystallites after annealing at 433 K. The electrical properties of MV2B thin films have been studied. There are a number of operational environments where the performance of MV2B thin films is likely to be affected significantly on their electrical properties and dielectric constants such as the differences of film thicknesses, temperatures and frequencies. It was found that the DC conductivity of MV2B films increases with increasing temperature. The extrinsic conduction mechanism is operating in temperature range of 288-360 K with activation energy of 0.16 eV, and the conduction in extrinsic region is explained via applying Mott model for variable range hopping. The intrinsic conduction mechanism is operating in temperatures >360 K with activation energy of 0.91 eV. The conduction in intrinsic region is explained by applying band to band transitions theory. The AC electrical conductivity and dielectric relaxation of MV2B thin films in the temperature range 365-473 K and in frequency range 0.1-100 kHz has been also studied. It has been shown that theoretical curves generated from correlated barrier hopping, CBH, model gives the best fitting with experimental results. Analysis of these results proved that conduction occurs by phonon-assisted hopping between localized states and it is performed by bipolaron hopping mechanism. The temperature and frequency dependence of both the real and imaginary parts of dielectric constant have been investigated.

  12. Nonlinear optical and electrical conductivity properties of Carbon Nanotubes (CNT) doped in Sol-Gel matrices

    NASA Astrophysics Data System (ADS)

    Pokrass, Mariana; Burshtein, Zeev; Bar, Galit; Gvishi, Raz

    2014-09-01

    Carbon-nanotubes (CNT) are fascinating compounds, exhibiting exceptional electrical, thermal conductivity, mechanical strength, and nonlinear optical (NLO) properties. Their unique structures involve large ?-?* electronic clouds. The energy level schemes thus created allow many electronic transitions between the ground and the excited states. The present work involves CNT-doped hybrid organic-inorganic glass composites prepared by a Fast-sol-gel method. Such composite glasses solidify without shrinkage or crack formation, and exhibit promising properties as optical devices. In this work we have studied nonlinear optical and electrical conductivity properties. The CNT composite glasses exhibited enhanced absorption at 532 nm, and saturable absorption at 1064 nm. The enhanced absorption at 532 was attributed to 2-photon absorption; saturable absorption was attributed to depletion of the absorbing ground-state, and was analyzed using the modified Frantz-Nodvik equation. Absorption cross-sections were extracted for the saturable absorption phenomenon. Such CNT composites glasses may be used as "optical limiting" filters in lasers near 532 nm, or as saturable absorbing filters for passive laser Q-switching near 1064 nm. The CNT composites electrical conductivity was studied as a function of the CNT concentration and modeled by a percolation theory. The maximal measured conductivity was ? ?10-3 (?cm)-1 for the CNT composites, representing a conductivity increase of at least 12 orders of magnitude compared to that of pure silica. A quite low percolation threshold was obtained, ?c = 0.22 wt.% CNT. Electrostatic Force Microscopy (EFM) and Conductive mode Atomic Force Microscopy (C-AFM) studies revealed that the conductivity occurs at the micro-level among the CNTs dispersed in the matrix.

  13. Interior-architectured ZnO nanostructure for enhanced electrical conductivity via stepwise fabrication process

    PubMed Central

    2014-01-01

    Fabrication of ZnO nanostructure via direct patterning based on sol-gel process has advantages of low-cost, vacuum-free, and rapid process and producibility on flexible or non-uniform substrates. Recently, it has been applied in light-emitting devices and advanced nanopatterning. However, application as an electrically conducting layer processed at low temperature has been limited by its high resistivity due to interior structure. In this paper, we report interior-architecturing of sol-gel-based ZnO nanostructure for the enhanced electrical conductivity. Stepwise fabrication process combining the nanoimprint lithography (NIL) process with an additional growth process was newly applied. Changes in morphology, interior structure, and electrical characteristics of the fabricated ZnO nanolines were analyzed. It was shown that filling structural voids in ZnO nanolines with nanocrystalline ZnO contributed to reducing electrical resistivity. Both rigid and flexible substrates were adopted for the device implementation, and the robustness of ZnO nanostructure on flexible substrate was verified. Interior-architecturing of ZnO nanostructure lends itself well to the tunability of morphological, electrical, and optical characteristics of nanopatterned inorganic materials with the large-area, low-cost, and low-temperature producibility. PMID:25258595

  14. Electric-hydraulic conductivity correlation in fractured crystalline bedrock: Central Landfill, Rhode Island, USA

    NASA Astrophysics Data System (ADS)

    Frohlich, Reinhard K.; Fisher, John J.; Summerly, E.

    1996-10-01

    Remote sensing and geoelectrical methods were used to find water-bearing fractures in the Scituate granite under the Central Landfill of Rhode Island. These studies were necessary to evaluate the integrity of the sanitary landfill and for planning safe landfill extensions. The most useful results were obtained with fracture trace analysis using Landsat and SLAR imagery in combination with ground-based resistivity measurements using Schlumberger vertical electrical soundings based on the assumption of horizontally layered strata. Test borings and packer tests confirmed, in the presence of a lineament and low bedrock resistivity, the probable existence of high bedrock fracture density and high average hydraulic conductivity. However, not every lineament was found to be associated with high fracture density and high hydraulic conductivity. Lineaments alone are not a reliable basis for characterising a landfill site as being affected by fractured bedrock. Horizontal fractures were found in borings located away from lineaments. High values of hydraulic conductivity were correlated with low bedrock resistivities. Bedrock resistivities between 60 and 700 ? m were associated with average hydraulic conductivities between 4 and 60 cm/day. In some cases very low resistivities were confined to the upper part of the bedrock where the hydraulic conductivity was very large. These types of fractures apparently become narrower in aperture with depth. Bedrock zones having resistivities greater than 1000 ? m showed, without exception, no flow to the test wells. Plots of bedrock resistivity versus the average hydraulic conductivity indicate that the resistivity decreases with increasing hydraulic conductivity. This relationship is inverse to that found in most unconsolidated sediments and is useful for estimating the hydraulic conductivity in groundwater surveys in fractured bedrock. In appropriate settings such as the Central Landfill site in New England, this electric-hydraulic correlation relationship, supplemented by lineament trace analysis, can be used effectively to estimate the hydraulic conductivity in bedrock from only a limited number of resistivity depth soundings and test wells.

  15. A new method of calculating electrical conductivity with applications to natural waters

    NASA Astrophysics Data System (ADS)

    McCleskey, R. Blaine; Nordstrom, D. Kirk; Ryan, Joseph N.; Ball, James W.

    2012-01-01

    A new method is presented for calculating the electrical conductivity of natural waters that is accurate over a large range of effective ionic strength (0.0004-0.7 mol kg-1), temperature (0-95 °C), pH (1-10), and conductivity (30-70,000 ?S cm-1). The method incorporates a reliable set of equations to calculate the ionic molal conductivities of cations and anions (H+, Li+, Na+, K+, Cs+, NH4+, Mg2+, Ca2+, Sr2+, Ba2+, F-, Cl-, Br-, SO42-, HCO3-, CO32-, NO3-, and OH-), environmentally important trace metals (Al3+, Cu2+, Fe2+, Fe3+, Mn2+, and Zn2+), and ion pairs (HSO4-, NaSO4-, NaCO3-, and KSO4-). These equations are based on new electrical conductivity measurements for electrolytes found in a wide range of natural waters. In addition, the method is coupled to a geochemical speciation model that is used to calculate the speciated concentrations required for accurate conductivity calculations. The method was thoroughly tested by calculating the conductivities of 1593 natural water samples and the mean difference between the calculated and measured conductivities was -0.7 ± 5%. Many of the samples tested were selected to determine the limits of the method and include acid mine waters, geothermal waters, seawater, dilute mountain waters, and river water impacted by municipal waste water. Transport numbers were calculated and H+, Na+, Ca2+, Mg2+, NH4+, K+, Cl-, SO42-, HCO3-, CO32-, F-, Al3+, Fe2+, NO3-, and HSO4-substantially contributed (>10%) to the conductivity of at least one of the samples. Conductivity imbalance in conjunction with charge imbalance can be used to identify whether a cation or an anion measurement is likely in error, thereby providing an additional quality assurance/quality control constraint on water analyses.

  16. A new method of calculating electrical conductivity with applications to natural waters

    USGS Publications Warehouse

    McCleskey, R. Blaine; Nordstrom, D. Kirk; Ryan, Joseph N.; Ball, James W.

    2012-01-01

    A new method is presented for calculating the electrical conductivity of natural waters that is accurate over a large range of effective ionic strength (0.0004–0.7 mol kg-1), temperature (0–95 °C), pH (1–10), and conductivity (30–70,000 ?S cm-1). The method incorporates a reliable set of equations to calculate the ionic molal conductivities of cations and anions (H+, Li+, Na+, K+, Cs+, NH4+, Mg2+, Ca2+, Sr2+, Ba2+, F-, Cl-, Br-, SO42-, HCO3-, CO32-, NO3-, and OH-), environmentally important trace metals (Al3+, Cu2+, Fe2+, Fe3+, Mn2+, and Zn2+), and ion pairs (HSO4-, NaSO4-, NaCO3-, and KSO4-). These equations are based on new electrical conductivity measurements for electrolytes found in a wide range of natural waters. In addition, the method is coupled to a geochemical speciation model that is used to calculate the speciated concentrations required for accurate conductivity calculations. The method was thoroughly tested by calculating the conductivities of 1593 natural water samples and the mean difference between the calculated and measured conductivities was -0.7 ± 5%. Many of the samples tested were selected to determine the limits of the method and include acid mine waters, geothermal waters, seawater, dilute mountain waters, and river water impacted by municipal waste water. Transport numbers were calculated and H+, Na+, Ca2+, Mg2+, NH4+, K+, Cl-, SO42-, HCO3-, CO32-, F-, Al3+, Fe2+, NO3-, and HSO4- substantially contributed (>10%) to the conductivity of at least one of the samples. Conductivity imbalance in conjunction with charge imbalance can be used to identify whether a cation or an anion measurement is likely in error, thereby providing an additional quality assurance/quality control constraint on water analyses.

  17. 76 FR 49463 - Pacific Gas and Electric Company; Notice of Authorization for Continued Project Operation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ... Project Operation On June 16, 2009, Pacific Gas and Electric Company, licensee for the McCloud-Pit... Commission's regulations thereunder. The McCloud-Pit Hydroelectric Project is located on the McCloud and Pit... authorized to continue operation of the McCloud-Pit Hydroelectric Project, until such time as the...

  18. Novel flexible belt-shaped coaxial microcables with tunable multicolor luminescence, electrical conductivity and magnetism.

    PubMed

    Shao, Hong; Ma, Qianli; Dong, Xiangting; Yu, Wensheng; Yang, Ming; Yang, Ying; Wang, Jinxian; Liu, Guixia

    2015-09-14

    A novel type of flexible [Fe3O4/PANI/PMMA]@{[Eu(BA)3phen + Tb(BA)3phen]/PMMA} (PMMA = polymethyl methacrylate, BA = benzoic acid, phen = phenanthroline, PANI = polyaniline) belt-shaped coaxial microcable possessing electrical conductivity, magnetism and color-tunable photoluminescence has been successfully fabricated by electrospinning technology using a specially designed coaxial spinneret. Every strip of belt-shaped coaxial microcable is assembled with a Fe3O4/PANI/PMMA electrically conductive -magnetic bifunctional core and a [Eu(BA)3phen + Tb(BA)3phen]/PMMA insulative and photoluminescence-tunable shell. The conductivity of the core of belt-shaped coaxial microcables reaches up to the order of 10(-2) S cm(-1) and all belt-shaped coaxial microcables are insulated from each other. The tuning of emission color is possible by changing the Eu(3+)/Tb(3+) molar ratio of the belt-shaped coaxial microcables. The electrical conductivity, magnetic and photoluminescence properties of belt-shaped coaxial microcables can be tuned by adjusting the content of PANI, Fe3O4 nanoparticles (NPs) and rare earth complexes. More importantly, the proposed design idea and the construction technique are universal regarding the preparation of other multifunctional one-dimensional micromaterials. PMID:26235223

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

    SciTech Connect

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

    1984-03-01

    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 V/cm, the character of this relationship is determined mainly by the formation of conducting chains of water drops, which greatly increase the emulsion EC. It is determined that from the values of the EC measured in a low-strength field, it is impossible to judge the mechanism of electrical conduction of an emulsion in high-strength fields that are characteristic for the electrocoalescence process. Measurements were conducted at intermediate field strengths with average values E /SUB av/ of 2 and 6kV/cm, with a 50-Hz ac field, an emulsion flow velocity of 5.1 cm/sec, and an aqueous disperse phase content of 4%, using a coaxial cylindrical cell. The results from the measurements show that the presence of a demulsifier in the W/O emulsion affects its EC, with this effect depending to different degrees on the type of demulsifier, the concentration of demulsifier, and the field strength. It is established that the EC drops off with increasing demulsifier concentration in the emulsion.

  20. Spectroscopic determination of electrical conductivity in an MHD duct from absolute intensity measurements

    NASA Technical Reports Server (NTRS)

    Wang, S. Y.; Smith, J. M.

    1977-01-01

    Measurements of the electrical conductivity in the NASA Lewis cesium seeded, H2-O2 MHD duct made by applying a voltage across the channel from one end electrode to the other, measuring the current, and using the inner electrodes as probes to monitor the voltage distribution along the channel were found to be in good agreement with theory except at low combustion pressures and/or high ratios of seed/oxygen mass flows. To corroborate these measurements and to analyze the possibility of nonuniform seed injection as a cause of the above deviations, a spectroscopic investigation of the plasma conductivity was undertaken. Radial profiles of emission coefficient were obtained from measured transverse profiles of the absolute integrated intensity by Abel inversion. Radial profiles of electrical conductivity were then obtained under two different assumptions. In the first the Cs seed fraction is assumed uniform and equal to the measured flow rate at the time when the temperature and conductivity were obtained. In the second method the local temperature and pressure are taken to be those given by a one-dimensional channel calculation including heat transfer and friction. The results of the two methods are compared to the previously measured conductivity.