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Sample records for conductivity loggingtec hnique

  1. 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.

  2. 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)

  3. Conduct disorder

    MedlinePlus

    Disruptive behavior - child; Impulse control problem - child ... Conduct disorder has been linked to: Child abuse Drug or alcohol abuse in the parents Family conflicts Genetic defects Poverty The diagnosis is more common among boys. It is ...

  4. 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)

  5. Appropriate Conduct

    ERIC Educational Resources Information Center

    Di Lullo, Louis

    2004-01-01

    Many years ago when the author assumed the role of assistant principal for school climate, discipline, and attendance, he inherited many school policies and guidelines that were outdated, unfair, and without merit in the current school climate. Because the school conduct code had not been revised since the school opened in 1960, many of the…

  6. Conducting Meetings.

    ERIC Educational Resources Information Center

    United Tribes Educational Technical Center, Bismarck, ND.

    Written for anyone interested in what makes a meeting run smoothly (and what doesn't), the guide for conducting meetings is divided into the following sections: the chairperson (his/her responsibilities, preparing an agenda, organizing discussions); the meeting (quorums, discussions, points of order, and clarification); the motion (making the…

  7. Electrodeless conductivity.

    PubMed

    Light, T S; McHale, E J; Fletcher, K S

    1989-01-01

    Electrodeless conductivity is a technique for measuring the concentration of electrolytes in solution and utilizes a probe consisting of two toroids in close proximity, both of which are immersed in the solution. In special cases, the toroids may be mounted externally on insulated pipes carrying the solution. One toroid radiates an alternating electric field in the audiofrequency range and the other acts as a receiver to pick up the small current induced by the ions moving in a conducting loop of solution. Coatings which would foul contacting electrodes, such as suspensions, precipitates or oil, have little or no effect. Applications are chiefly to continuous measurement in the chemical processing industries, including pulp and paper, mining and heavy chemical production. The principles and practical details of the method are reviewed and cell-diameter, wall, and temperature effects are discussed. PMID:18964695

  8. Heat conduction

    SciTech Connect

    Lilley, D.G.

    1987-01-01

    Analytical and numerical methods, including both finite difference and finite element techniques, are presented with applications to heat conduction problems. Numerical and analytical methods are integrated throughout the text and a variety of complexities are thoroughly treated with many problems, solutions and computer programs. This book is presented as a fundamental course suitable for senior undergraduate and first year graduate students, with end-of-chapter problems and answers included. Sample case studies and suggested projects are included.

  9. Conduction apraxia.

    PubMed

    Ochipa, C; Rothi, L J; Heilman, K M

    1994-10-01

    A left hemisphere damaged patient with ideomotor apraxia is described, whose performance on pantomime to verbal command was superior to pantomime imitation. His reception of these same gestures (gesture naming) was spared. This syndrome has been named conduction apraxia. To account for this selective impaired performance on gesture imitation, a separation of the representations for gesture production and reception is proposed and a non-lexical gesture processing route for gesture imitation is suggested. PMID:7931387

  10. Conductivity Probe

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air.

    The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air.

    The needles on the probe are 15 millimeters (0.6 inch) long.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  11. Conducting a thermal conductivity survey

    NASA Technical Reports Server (NTRS)

    Allen, P. B.

    1985-01-01

    A physically transparent approximate theory of phonon decay rates is presented starting from a pair potential model of the interatomic forces in an insulator or semiconductor. The theory applies in the classical regime and relates the 3-phonon decay rate to the third derivative of the pair potential. Phonon dispersion relations do not need to be calculated, as sum rules relate all the needed quantities directly to the pair potential. The Brillouin zone averaged phonon lifetime turns out to involve a dimensionless measure of the anharmonicity multiplied by an effective density of states for 3-phonon decay. Results are given for rare gas and alkali halide crystals. For rare gases, the results are in good agreement with more elaborate perturbation calculations. Comparison to experimental data on phonon linewidths and thermal conductivity are made.

  12. Heat conduction in conducting polyaniline nanofibers

    NASA Astrophysics Data System (ADS)

    Nath, Chandrani; Kumar, A.; Syu, K.-Z.; Kuo, Y.-K.

    2013-09-01

    Thermal conductivity and specific heat of conducting polyaniline nanofibers are measured to identify the nature of heat carrying modes combined with their inhomogeneous structure. The low temperature thermal conductivity results reveal crystalline nature while the high temperature data confirm the amorphous nature of the material suggesting heterogeneous model for conducting polyaniline. Extended acoustic phonons dominate the low temperature (<100 K) heat conduction, while localized optical phonons hopping, assisted by the extended acoustic modes, account for the high temperature (>100 K) heat conduction.

  13. Conducting Compositions of Matter

    NASA Technical Reports Server (NTRS)

    Viswanathan, Tito (Inventor)

    1999-01-01

    The invention provides conductive compositions of matter, as well as methods for the preparation of the conductive compositions of matter, solutions comprising the conductive compositions of matter, and methods of preparing fibers or fabrics having improved anti-static properties employing the conductive compositions of matter.

  14. Conducting compositions of matter

    NASA Technical Reports Server (NTRS)

    Viswanathan, Tito (Inventor)

    2000-01-01

    The invention provides conductive compositions of matter, as well as methods for the preparation of the conductive compositions of matter, solutions comprising the conductive compositions of matter, and methods of preparing fibers or fabrics having improved anti-static properties employing the conductive compositions of matter.

  15. Nerve conduction velocity

    MedlinePlus

    Nerve conduction velocity (NCV) is a test to see how fast electrical signals move through a nerve. ... normal body temperature. Being too cold slows nerve conduction. Tell your doctor if you have a cardiac ...

  16. Nerve conduction velocity

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003927.htm Nerve conduction velocity To use the sharing features on this page, please enable JavaScript. Nerve conduction velocity (NCV) is a test to see how ...

  17. The Conductivity of Solutions.

    ERIC Educational Resources Information Center

    Rayner-Canham, Geoff

    1993-01-01

    Presents historical background and modern explanations for the popular demonstration of showing conductivity of solutions through the insertion of a light-bulb conductivity tester into deionized water and water with salt in it. (PR)

  18. Surface Conductive Glass.

    ERIC Educational Resources Information Center

    Tanaka, John; Suib, Steven L.

    1984-01-01

    Discusses the properties of surface-conducting glass and the chemical nature of surface-conducting stannic (tin) oxide. Also provides the procedures necessary for the preparation of surface-conducting stannic oxide films on glass substrates. The experiment is suitable for the advanced inorganic chemistry laboratory. (JN)

  19. Electrically conductive composite material

    DOEpatents

    Clough, Roger L.; Sylwester, Alan P.

    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.

  20. 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.

  1. High conductance surge cable

    DOEpatents

    Murray, Matthew M.; Wilfong, Dennis H.; Lomax, Ralph E.

    1998-01-01

    An electrical cable for connecting transient voltage surge suppressers to ectrical power panels. A strip of electrically conductive foil defines a longitudinal axis, with a length of an electrical conductor electrically attached to the metallic foil along the longitudinal axis. The strip of electrically conductive foil and the length of an electrical conductor are covered by an insulating material. For impedance matching purposes, triangular sections can be removed from the ends of the electrically conductive foil at the time of installation.

  2. High conductance surge cable

    DOEpatents

    Murray, M.M.; Wilfong, D.H.; Lomax, R.E.

    1998-12-08

    An electrical cable for connecting transient voltage surge suppressors to electrical power panels. A strip of electrically conductive foil defines a longitudinal axis, with a length of an electrical conductor electrically attached to the metallic foil along the longitudinal axis. The strip of electrically conductive foil and the length of an electrical conductor are covered by an insulating material. For impedance matching purposes, triangular sections can be removed from the ends of the electrically conductive foil at the time of installation. 6 figs.

  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. Codes of Conduct

    ERIC Educational Resources Information Center

    Million, June

    2004-01-01

    Most schools have a code of conduct, pledge, or behavioral standards, set by the district or school board with the school community. In this article, the author features some schools that created a new vision of instilling code of conducts to students based on work quality, respect, safety and courtesy. She suggests that communicating the code…

  5. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg; Fischer, Anne ,; Bennett, Jason; Lowe, Michael

    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.

  6. Conductive Critical Thinking

    ERIC Educational Resources Information Center

    Paetkau, Mark

    2007-01-01

    One of my goals as an instructor is to teach students critical thinking skills. This paper presents an example of a student-led discussion of heat conduction at the first-year level. Heat loss from a human head is calculated using conduction and radiation models. The results of these plausible (but wrong) models of heat transfer contradict what…

  7. Conductive Education Evaluated.

    ERIC Educational Resources Information Center

    Stukat, Karl Gustav

    1995-01-01

    This paper evaluates two research projects concerned with conductive education for children with cerebral palsy, one in Germany and the other in the United Kingdom. Issues of generalizability and drawing causal conclusions are raised. The paper finds that neither the most sanguine expectations nor the worst misgivings about conductive education…

  8. Conductive fabric seal

    DOEpatents

    Livesay, Ronald Jason; Mason, Brandon William; Kuhn, Michael Joseph; Rowe, Nathan Carl

    2015-10-13

    Disclosed are several examples of a system and method for detecting if an article is being tampered with. Included is a covering made of a substrate that is coated with a layer of an electrically conductive material that forms an electrically conductive surface having an electrical resistance. The covering is configured to at least partially encapsulate the article such that the article cannot be tampered with, without modifying the electrical resistance of the electrically conductive surface of the covering. A sensing device is affixed to the electrically conductive surface of the covering and the sensing device monitors the condition of the covering by producing a signal that is indicative of the electrical resistance of the electrically conductive surface of the covering. A measured electrical resistance that differs from a nominal electrical resistance is indicative of a covering that is being tampered with and an alert is communicated to an observer.

  9. Nanocarbonic transparent conductive films.

    PubMed

    Roth, Siegmar; Park, Hye Jin

    2010-07-01

    This tutorial review discusses the contradictory material properties of electrical conductivity and optical transparency for the examples of graphene films and carbon nanotube networks. It is argued that for homogeneous films both properties are linked by basic laws of physics and that for perfect monoatomic layers conductivity and transparency can be calculated from the fine structure constant. To beat these limitations, inhomogeneous films are required, such as graphene with an array of holes or nanotube networks. An overview is given on literature values of transparency and conductivity, both for graphene films and for nanotube networks. PMID:20502813

  10. Cardiac conduction system

    MedlinePlus Videos and Cool Tools

    ... signals to the heart muscle causing it to contract. The main components of the cardiac conduction system ... the sequence by causing the atrial muscles to contract. From there, the signal travels to the AV ...

  11. Conductive open frameworks

    DOEpatents

    Yaghi, Omar M.; Wan, Shun; Doonan, Christian J.; Wang, Bo; Deng, Hexiang

    2016-02-23

    The disclosure relates generally to materials that comprise conductive covalent organic frameworks. The disclosure also relates to materials that are useful to store and separate gas molecules and sensors.

  12. 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.

  13. Cardiac conduction system

    MedlinePlus Videos and Cool Tools

    ... cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract. The main components ... the cardiac conduction system’s electrical activity in the heart.

  14. Solution Conductivity Apparatus.

    ERIC Educational Resources Information Center

    Haworth, Daniel T.; Bartelt, Mark R.; Kenney, Michael J.

    1999-01-01

    Describes the construction of a conductivity meter that includes a timer and a readout display that provides semiquantitative information. The meter can be made into a hand-held or lecture hall (demonstration) version. (WRM)

  15. Electrically conductive material

    DOEpatents

    Singh, Jitendra P.; Bosak, Andrea L.; McPheeters, Charles C.; Dees, Dennis W.

    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.

  16. Proton conducting cerate ceramics

    SciTech Connect

    Coffey, G.W.; Pederson, L.R.; Armstrong, T.R.; Bates, J.L.; Weber, W.J.

    1995-08-01

    Cerate perovskites of the general formula AM{sub x}Ce{sub 1-x}O{sub 3-{delta}}, where A = Sr or Ba and where M = Gd, Nd, Y, Yb or other rare earth dopant, are known to conduct a protonic current. Such materials may be useful as the electrolyte in a solid oxide fuel cell operating at intermediate temperatures, as an electrochemical hydrogen separation membrane, or as a hydrogen sensor. Conduction mechanisms in these materials were evaluated using dc cyclic voltammetry and mass spectrometry, allowing currents and activation energies for proton, electron, and oxygen ion contributions to the total current to be determined. For SrYb{sub 0.05}Ce{sub 0.95}O{sub 3-{delta}}, one of the best and most environmentally stable compositions, proton conduction followed two different mechanisms: a low temperature process, characterized by an activation energy of 0.42{+-}0.04 eV, and a high temperature process, characterized by an activation energy of 1.38{+-}0.13 eV. It is believed that the low temperature process is dominated by grain boundary conduction while bulk conduction is responsible for the high temperature process. The activation energy for oxygen ion conduction (0.97{+-}0.10 eV) agrees well with other oxygen conductors, while that for electronic conduction, 0.90{+-}0.09 eV, is affected by a temperature-dependent electron carrier concentration. Evaluated by direct measurement of mass flux through a dense ceramic with an applied dc field, oxygen ions were determined to be the majority charge carrier except at the lowest temperatures, followed by electrons and then protons.

  17. Transparent conducting oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

    2014-09-01

    Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10-4 Ωcm at T = 300 K (compared to 6.5 × 10-1 Ωcm for nominally undoped nanotubes) to 2.2 × 10-4 Ωcm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples.

  18. Transparent conducting oxide nanotubes.

    PubMed

    Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

    2014-09-26

    Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10(-4) Ωcm at T = 300 K (compared to 6.5 × 10(-1) Ωcm for nominally undoped nanotubes) to 2.2 × 10(-4) Ωcm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples. PMID:25180635

  19. Cartilage conduction hearing.

    PubMed

    Shimokura, Ryota; Hosoi, Hiroshi; Nishimura, Tadashi; Yamanaka, Toshiaki; Levitt, Harry

    2014-04-01

    Sound information is known to travel to the cochlea via either air or bone conduction. However, a vibration signal, delivered to the aural cartilage via a transducer, can also produce a clearly audible sound. This type of conduction has been termed "cartilage conduction." The aural cartilage forms the outer ear and is distributed around the exterior half of the external auditory canal. In cartilage conduction, the cartilage and transducer play the roles of a diaphragm and voice coil of a loudspeaker, respectively. There is a large gap between the impedances of cartilage and skull bone, such that cartilage vibrations are not easily transmitted through bone. Thus, these methods of conduction are distinct. In this study, force was used to apply a transducer to aural cartilage, and it was found that the sound in the auditory canal was amplified, especially for frequencies below 2 kHz. This effect was most pronounced at an application force of 1 N, which is low enough to ensure comfort in the design of hearing aids. The possibility of using force adjustments to vary amplification may also have applications for cell phone design. PMID:25234994

  20. Proliferating conduction by isomerism

    NASA Astrophysics Data System (ADS)

    Kaur, Rupan Preet; Sawhney, Ravinder Singh; Engles, Derick

    2015-01-01

    The electrical conduction of isomers of anthracene molecule attached between two semi-infinite gold electrodes was simulated using extended Huckel theory (EHT)-based on semi-empirical model in this research work. The electron transport parameters were examined in two epochs by buffering anthracene and its isomer phenanthrene alternatively between gold electrodes using sulphur as an alligator clip, under variegated bias voltages. Differential NDR effect was observed in both the cases but phenanthrene exhibited more linear I-V curve than its counterpart, anthracene. The simulated results discovered phenanthrene as a better candidate than anthracene towards contributing to electrical conduction in molecular junctions. Phenanthrene reported maximum conductance of 0.74G0 whereas anthracene exhibited 0.03G0 at 0.8V.

  1. Low thermal conductivity oxides

    SciTech Connect

    Pan, Wei; Phillpot, Simon R.; Wan, Chunlei; Chernatynskiy, Aleksandr; Qu, Zhixue

    2012-10-09

    Oxides hold great promise as new and improved materials for thermal-barrier coating applications. The rich variety of structures and compositions of the materials in this class, and the ease with which they can be doped, allow the exploration of various mechanisms for lowering thermal conductivity. In this article, we review recent progress in identifying specific oxides with low thermal conductivity from both theoretical and experimental perspectives. We explore the mechanisms of lowering thermal conductivity, such as introducing structural/chemical disorder, increasing material density, increasing the number of atoms in the primitive cell, and exploiting the structural anisotropy. We conclude that further systematic exploration of oxide crystal structures and chemistries are likely to result in even further improved thermal-barrier coatings.

  2. 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.

  3. Transparent Conductive Nanostructures

    SciTech Connect

    2008-06-22

    The objectives of this program between UT-Battelle, LLC (the ''Contractor'') and (Battelle Memorial Institute) (the "Participant") were directed towards achieving significant improvement: in the electrical conductivity and optical/infrared transmission of single-wall carbon nanotube (SWNT)-based composite materials. These materials will be used in coating applications that range from aircraft canopies to display applications. The goal of the project was to obtain supported mats of SWNTs with sheet conductivities approaching 10 ohms/square combined with high optical transmission (>85% transmission at 550 nm), thereby permitting their application as a replacement for indium tin oxide (ITO) in a variety of applications such as flexible displays.

  4. Conducting hybrid polymeric systems

    SciTech Connect

    Aldissi, M.; White, J.W.; Agnew, S.; Jorgensen, B.S.

    1987-09-01

    The studies took advantage of the opportunities offered by copolymerization for gaining insight into electrical conduction, morphology, phase separation, polymer-polymer interfaces, and solubility. Copolymerization is technologically important for it allows one to tailor-make products with specifically desired properties. However, the utility of copolymerization involving conjugated, rigid components could be different from that of conventional polymers. This paper is focused on the synthesis and properties of various materials: Rod-coil systems such as polyisoprene/polyacetylene diblock copolymers (resonance raman and small angle neutron scattering studies correlated to conductivity); and alternating copolymers such as poly (arylpyrroles) (electrochemical synthesis and characterization). 8 refs., 4 figs.

  5. Thermal conductivity of metals

    NASA Technical Reports Server (NTRS)

    Kazem, Sayyed M.

    1990-01-01

    The objective is to familiarize students with steady and unsteady heat transfer by conduction and with the effect of thermal conductivity upon temperature distribution through a homogeneous substance. The elementary heat conduction experiment presented is designed for associate degree technology students in a simple manner to enhance their intuition and to clarify many confusing concepts such as temperature, thermal energy, thermal conductivity, heat, transient and steady flows. The equipment set is safe, small, portable (10 kg) and relatively cheap (about $1200): the electric hot plate 2 kg (4.4 lb) for $175: the 24 channel selector and Thermocouple Digital Readout (Trendicator) 4.5 kg (10 lb) for about $1000; the three metal specimens (each of 2.5 cm diameter and 11 cm length), base plate and the bucket all about 3 kg (7 lb) for about $25. The experiment may take from 60 to 70 minutes. Although the hot plate surface temperature could be set from 90 to 370 C (maximum of 750 watts) it is a good practice to work with temperatures of 180 to 200 C (about 400 watts). They may experiment in squads of 2, 3 or even 4, or the instructor may demonstrate it for the whole class.

  6. Conductive Education Perspectives.

    ERIC Educational Resources Information Center

    Spivack, Frieda

    1995-01-01

    This article describes conductive education for children with neuromotor disabilities and identifies its major concepts, including orthofunction, rhythmic intention, and verbal regulation. Also addressed are the role of the conductor and the group and the training of conductors at the Peto Institute in Hungary. Research on the method's…

  7. Lithium ion conducting electrolytes

    DOEpatents

    Angell, C. Austen; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte having exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH.sub.3 CN) succinnonitrile (CH.sub.2 CN).sub.2, and tetraglyme (CH.sub.3 --O--CH.sub.2 --CH.sub.2 --O--).sub.2 (or like solvents) solvated to a Mg.sup.+2 cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100.degree. C. conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone.

  8. Lithium ion conducting electrolytes

    DOEpatents

    Angell, C.A.; Liu, C.

    1996-04-09

    A liquid, predominantly lithium-conducting, ionic electrolyte is described having exceptionally high conductivity at temperatures of 100 C or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH{sub 3}CN), succinnonitrile (CH{sub 2}CN){sub 2}, and tetraglyme (CH{sub 3}--O--CH{sub 2}--CH{sub 2}--O--){sub 2} (or like solvents) solvated to a Mg{sup +2} cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100 C conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone. 2 figs.

  9. Low electrolytic conductivity standards

    SciTech Connect

    Wu, Y.C.; Berezansky, P.A.

    1995-09-01

    The monitoring and control of the quality of feedwater and boiler water are necessary for power plants. The generation of steam at high temperature and pressure requires that contaminants be strictly limited to very low levels to prevent corrosion and scaling. Standards of low electrolytic conductivity were developed to satisfy the demands of the US Navy and American industry for the measurement of high quality water. The criteria for the selection of appropriate solvent and solutes, based on the principles of equivalent conductivity and Onsager`s limiting law, are described. Dilute solutions of potassium chloride and benzoic acid in 30% n-propanol-water have been chosen as standards. The electrolytic conductivity of both sets of these solutions as a function of molality was determined. Solutions of potassium chloride and of benzoic acid are recommended for use as 5, 10, 15, 20, and 25 {micro}S/cm conductivity standards. Solutions prepared from potassium chloride in 30% n-propanol-water have been certified as Standard Reference Materials (SRMs). SRM 3198 and SRM 3199 are certified nominally at 5 and 15 {micro}S/cm, respectively, at 25.000 C.

  10. Lithium ion conducting electrolytes

    SciTech Connect

    Angell, C.A.; Liu, C.; Xu, K.; Skotheim, T.A.

    1999-10-05

    The present invention relates generally to highly conductive alkali-metal ion non-crystalline electrolyte systems, and more particularly to novel and unique molten (liquid), rubbery, and solid electrolyte systems which are especially well suited for use with high current density electrolytic cells such as primary and secondary batteries.

  11. Conductance Steamflow relationship

    SciTech Connect

    Whitney Trainor-Guitton

    2015-04-01

    These histograms represent our calibration of conductance of a volcanic geothermal field (with a clay cap) and the observed steam flow rates. See the following paper for further description: Trainor-Guitton, Hoversten,Nordquist, Intani, Value of information analysis using geothermal field data: accounting for multiple interpretations & determining new drilling locations. SEG Abstracts 2015.

  12. Lithium ion conducting electrolytes

    DOEpatents

    Angell, Charles Austen; Liu, Changle; Xu, Kang; Skotheim, Terje A.

    1999-01-01

    The present invention relates generally to highly conductive alkali-metal ion non-crystalline electrolyte systems, and more particularly to novel and unique molten (liquid), rubbery, and solid electrolyte systems which are especially well suited for use with high current density electrolytic cells such as primary and secondary batteries.

  13. Conducting the Heat

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Heat conduction plays an important role in the efficiency and life span of electronic components. To keep electronic components running efficiently and at a proper temperature, thermal management systems transfer heat generated from the components to thermal surfaces such as heat sinks, heat pipes, radiators, or heat spreaders. Thermal surfaces absorb the heat from the electrical components and dissipate it into the environment, preventing overheating. To ensure the best contact between electrical components and thermal surfaces, thermal interface materials are applied. In addition to having high conductivity, ideal thermal interface materials should be compliant to conform to the components, increasing the surface contact. While many different types of interface materials exist for varying purposes, Energy Science Laboratories, Inc. (ESLI), of San Diego, California, proposed using carbon velvets as thermal interface materials for general aerospace and electronics applications. NASA s Johnson Space Center granted ESLI a Small Business Innovation Research (SBIR) contract to develop thermal interface materials that are lightweight and compliant, and demonstrate high thermal conductance even for nonflat surfaces. Through Phase II SBIR work, ESLI created Vel-Therm for the commercial market. Vel-Therm is a soft, carbon fiber velvet consisting of numerous high thermal conductivity carbon fibers anchored in a thin layer of adhesive. The velvets are fabricated by precision cutting continuous carbon fiber tows and electrostatically flocking the fibers into uncured adhesive, using proprietary techniques.

  14. Interface Conductance Modal Analysis

    NASA Astrophysics Data System (ADS)

    Gordiz, Kiarash; Henry, Asegun

    2015-03-01

    Reliably and quantitatively calculating the conductance of phonons across an interface between two materials has been one of the major unresolved questions in thermal transport physics for the last century. Theories have been presented in this regard, but their predictive power is limited. A new formalism to extract the modal contributions to thermal interface conductance with full inclusion of temperature dependent anharmonicity and all of the atom level topography is presented. The results indicate that when two materials are joined a new set of vibrational modes are required to correctly describe the transport across the interface. The new set of vibrational modes is inconsistent with the physical picture described by phonon gas model (PGM), because some of the most important modes are localized and non-propagating and therefore do not have a well-defined velocity nor do they impinge on the interface. Among these new modes, certain classifications emerge, as most modes extend at least partially into the other material. Localized interfacial modes are also present and exhibit a high conductance contribution on a per mode basis by strongly coupling to other types of vibrational modes. We apply our formalism to different interfaces and present thermal interface conductance accumulation functions, two-dimensional cross-correlation matrices, and a quantitative determination of the contributions arising from inelastic effects. The provided new perspective on interface thermal transport can open new gates towards deeper understanding of phonon-phonon and electron-phonon interactions around interfaces.

  15. Benefits of Conducting Research.

    ERIC Educational Resources Information Center

    Anderson, Frances E.

    2001-01-01

    Metaphors for researchers, such as a crusader; a traveler; an explorer; a miner; an astronaut; a biblical Daniel; a Samurai; and an archaeologist are discussed. Benefits of conducting research are enumerated, including building the knowledge base for art therapy; increasing professional opportunities; improving client care; and advancing the…

  16. Conducting Educational Design Research

    ERIC Educational Resources Information Center

    McKenney, Susan; Reeves, Thomas

    2012-01-01

    Educational design research blends scientific investigation with systematic development and implementation of solutions to educational problems. Empirical investigation is conducted in real learning settings--not laboratories--to craft usable and effective solutions. At the same time, the research is carefully structured to produce theoretical…

  17. Nanostructured conductive polymeric materials

    NASA Astrophysics Data System (ADS)

    Al-Saleh, Mohammed H.

    Conductive polymer composites (CPCs) are a suitable alternative to metals in many applications due to their light-weight, corrosion resistance, low cost, ease of processing and design flexibility. CPCs have been formulated using different types of conductive fillers. In this PhD thesis, the focus is on CPCs for electrostatic discharge (ESD) protection and electromagnetic interference (EMI) attenuation. Despite the versatility of conductive fillers, carbon black (CB) has been the dominant filler to make CPCs for ESD protection applications because CB/polymer composites have a cost advantage over all other CPCs. For EMI shielding, stainless steel fibres and metal coated fibers are the preferred fillers, however CPCs made of those fibers are not the dominant EMI shielding materials. Metal coated and polymer plated polymers are the most widely used EMI shielding options. The limited use of CPCs in the EMI shielding market is because the high filler loading required to formulate a composite with an adequate level of shielding remarkably increases the composite price. In order to increase the competitiveness of CPCs, percolation threshold should be minimized as much as possible and composites with high EMI shielding capabilities at low filler loading should be formulated because all conductive fillers are expensive compared to polymers. In this thesis, two different methodologies to reduce percolation threshold in CPCs have been successfully developed and a CPC with exceptional EMI shielding capability has been formulated using copper nanowires as conductive filler. The first percolation threshold reduction technique is based on the selective localization of CB at the interface of immiscible polymer blend. The technique requires adding a copolymer that prefers the blend's interface and for which CB nanoparticles has the highest affinity. The second method is based on producing a CPC powder and then using this powder as a conductive filler to produce composite by dry

  18. 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.

  19. [Disorders of intraventricular conduction].

    PubMed

    de Micheli, A; Medrano, G A

    1987-01-01

    An electrophysiologic approach to intraventricular conduction disturbances, preeminently functional phenomena, is presented. They are divided into two groups: the proximal type corresponding to obstruction of excitation impulses in the main trunk of one intraventricular specific system; distal or peripheral type, due to an obstruction in the distal subdivisions of the system (fascicular) or to regional myocardial alterations (parietal). Trunkal blocks produce global delay of the activation sequence of the ipsilateral ventricular myocardium. Consequently they are recognized by slurred R waves and delayed time of onset of intrinsicoid deflection in all ipsilateral leads. Distal or peripheral blocks cause a segmentary delay of the activation phenomenon of ipsilateral ventricular myocardium. This is revealed by slurred R waves and delayed time of onset of intrinsicoid deflection only in those leads which explore the affected region. Peripheral blocks can be classified from a topographic point of view when they appear in the area of distal subdivisions of the intraventricular conduction system. PMID:2959227

  20. Oxygen ion conducting materials

    DOEpatents

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2005-07-12

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  1. Oxygen ion conducting materials

    DOEpatents

    Carter, J. David; Wang, Xiaoping; Vaughey, John; Krumpelt, Michael

    2004-11-23

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  2. Oxygen ion conducting materials

    DOEpatents

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2003-01-01

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  3. Highly Thermal Conductive Nanocomposites

    NASA Technical Reports Server (NTRS)

    Sun, Ya-Ping (Inventor); Connell, John W. (Inventor); Veca, Lucia Monica (Inventor)

    2015-01-01

    Disclosed are methods for forming carbon-based fillers as may be utilized in forming highly thermal conductive nanocomposite materials. Formation methods include treatment of an expanded graphite with an alcohol/water mixture followed by further exfoliation of the graphite to form extremely thin carbon nanosheets that are on the order of between about 2 and about 10 nanometers in thickness. Disclosed carbon nanosheets can be functionalized and/or can be incorporated in nanocomposites with extremely high thermal conductivities. Disclosed methods and materials can prove highly valuable in many technological applications including, for instance, in formation of heat management materials for protective clothing and as may be useful in space exploration or in others that require efficient yet light-weight and flexible thermal management solutions.

  4. Super ionic conductive glass

    DOEpatents

    Susman, Sherman; Volin, Kenneth J.

    1984-01-01

    An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  5. Super ionic conductive glass

    DOEpatents

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  6. Conductance of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, Supriyo; Anatram, M. P.

    1998-01-01

    The recent report of quantized conductance in a 4 m long multiwalled nanotube (MWNT) raises the exciting possibility of ballistic transport at room temperature over relatively long distances. We argue that this is made possible by the special symmetry of the eigenstates of the lowest propagating modes in metallic nanotubes which suppresses backscattering. This unusual effect is absent for the higher propagating modes so that transport is not ballistic once the bias exceeds the cut-off energy for the higher modes, which is estimated to be approximately 75 meV for nanotubes of diameter approximately 15 nm. Also, we show that the symmetry of the eigenstates can significantly affect their coupling to the reservoir and hence the contact resistance. A simple model is presented that can be used to understand the observed conductance-voltage characteristics.

  7. High conductivity composite metal

    DOEpatents

    Zhou, Ruoyi; Smith, James L.; Embury, John David

    1998-01-01

    Electrical conductors and methods of producing them, where the conductors possess both high strength and high conductivity. Conductors are comprised of carbon steel and a material chosen from a group consisting of copper, nickel, silver, and gold. Diffusion barriers are placed between these two materials. The components of a conductor are assembled and then the assembly is subjected to heat treating and mechanical deformation steps.

  8. High conductivity composite metal

    DOEpatents

    Zhou, R.; Smith, J.L.; Embury, J.D.

    1998-01-06

    Electrical conductors and methods of producing them are disclosed, where the conductors possess both high strength and high conductivity. Conductors are comprised of carbon steel and a material chosen from a group consisting of copper, nickel, silver, and gold. Diffusion barriers are placed between these two materials. The components of a conductor are assembled and then the assembly is subjected to heat treating and mechanical deformation steps. 10 figs.

  9. Conduction cooled tube supports

    DOEpatents

    Worley, Arthur C.; Becht, IV, Charles

    1984-01-01

    In boilers, process tubes are suspended by means of support studs that are in thermal contact with and attached to the metal roof casing of the boiler and the upper bend portions of the process tubes. The support studs are sufficiently short that when the boiler is in use, the support studs are cooled by conduction of heat to the process tubes and the roof casing thereby maintaining the temperature of the stud so that it does not exceed 1400.degree. F.

  10. Thermally conductive polymers

    NASA Technical Reports Server (NTRS)

    Byrd, N. R.; Jenkins, R. K.; Lister, J. L. (Inventor)

    1971-01-01

    A thermally conductive polymer is provided having physical and chemical properties suited to use as a medium for potting electrical components. The polymer is prepared from hydroquinone, phenol, and formaldehyde, by conventional procedures employed for the preparation of phenol-formaldehyde resins. While the proportions of the monomers can be varied, a preferred polymer is formed from the monomers in a 1:1:2.4 molar or ratio of hydroquinone:phenol:formaldehyde.

  11. Phoenix Conductivity Probe

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image taken by the Surface Stereo Imager on Sol 49, or the 49th Martian day of the mission (July 14, 2008), shows thermal and electrical conductivity probe on NASA's Phoenix Mars Lander's Robotic Arm.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  12. Conduction heat transfer solutions

    SciTech Connect

    VanSant, J.H.

    1983-08-01

    This text is a collection of solutions to a variety of heat conduction problems found in numerous publications, such as textbooks, handbooks, journals, reports, etc. Its purpose is to assemble these solutions into one source that can facilitate the search for a particular problem solution. Generally, it is intended to be a handbook on the subject of heat conduction. There are twelve sections of solutions which correspond with the class of problems found in each. Geometry, state, boundary conditions, and other categories are used to classify the problems. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. The introduction presents a synopsis on the theory, differential equations, and boundary conditions for conduction heat transfer. Some discussion is given on the use and interpretation of solutions. Supplementary data such as mathematical functions, convection correlations, and thermal properties are included for aiding the user in computing numerical values from the solutions. 155 figs., 92 refs., 9 tabs.

  13. Transparent conductive coatings

    NASA Technical Reports Server (NTRS)

    Ashok, S.

    1983-01-01

    Thin film transparent conductors are discussed. Materials with electrical conductivity and optical transparency are highly desirable in many optoelectronic applications including photovoltaics. Certain binary oxide semiconductors such as tin oxide (SnO2) and indium oxide (In2O3) offer much better performance tradeoff in optoelectronics as well as better mechanical and chemical stability than thin semitransparent films. These thin-film transparent conductors (TC) are essentially wide-bandgap degenerate semiconductors - invariably n-type - and hence are transparent to sub-bandgap (visible) radiation while affording high electrical conductivity due to the large free electron concentration. The principal performance characteristics of TC's are, of course, electrical conductivity and optical transmission. The TC's have a refractive index of around 2.0 and hence act as very efficient antireflection coatings. For using TC's in surface barrier solar cells, the photovoltaic barrier is of utmost importance and so the work function or electron affinity of the TC is also a very important material parameter. Fabrication processes are discussed.

  14. Conductance fluctuations in nanostructures

    NASA Astrophysics Data System (ADS)

    Zhu, Ningjia

    1997-12-01

    In this Ph.D thesis the conductance fluctuations of different physical origins in semi-conductor nanostructures were studied using both diagrammatic analytical methods and large scale numerical techniques. In the "mixed" transport regime where both mesoscopic and ballistic features play a role, for the first time I have analytically calculated the non-universal conductance fluctuations. This mixed regime is reached when impurities are distributed near the walls of a quantum wire, leaving the center region ballistic. I have discovered that the existence of a ballistic region destroys the universal conductance fluctuations. The crossover behavior of the fluctuation amplitude from the usual quasi-1D situation to that of the mixed regime is clearly revealed, and the role of various length scales are identified. My analytical predictions were confirmed by a direct numerical simulation by evaluating the Landauer formula. In another direction, I have made several studies of conductance or resistance oscillations and fluctuations in systems with artificial impurities in the ballistic regime. My calculation gave explanations of all the experimental results concerning the classical focusing peaks of the resistance versus magnetic field, the weak localization peak in a Sinai billiard system, the formation of a chaotic billiard, and predicted certain transport features which were indeed found experimentally. I have further extended the calculation to study the Hall resistance in a four-terminal quantum dot in which there is an antidot array. From my numerical data I analyzed the classical paths of electron motion and its quantum oscillations. The results compare well with recent experimental studies on similar systems. Since these billiard systems could provide quantum chaotic dynamics, I have made a detailed study of the consequence of such dynamics. In particular I have investigated the resonant transmission of electrons in these chaotic systems, and found that the level

  15. 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.

  16. Conducting Elite Performance Training.

    PubMed

    Silverman, Elliott; Tucker, Scott A; Imsdahl, Solveig; Charles, Justin A; Stellato, Mallory A; Wagner, Mercy D; Brown, Kimberly M

    2015-08-01

    Training to excellence in the conduct of surgical procedures has many similarities to the acquisition and mastery of technical skills in elite-level music and sports. By using coaching techniques and strategies gleaned from analysis of professional music ensembles and athletic training, surgical educators can set conditions that increase the success rate of training to elite performance. This article describes techniques and strategies used in both music and athletic coaching, and it discusses how they can be applied and integrated into surgical simulation and education. PMID:26210975

  17. Conducting polymer ultracapacitor

    DOEpatents

    Shi, Steven Z.; Davey, John R.; Gottesfeld, Shimshon; Ren, Xiaoming

    2002-01-01

    A sealed ultracapacitor assembly is formed with first and second electrodes of first and second conducting polymers electrodeposited on porous carbon paper substrates, where the first and second electrodes each define first and second exterior surfaces and first and second opposing surfaces. First and second current collector plates are bonded to the first and second exterior surfaces, respectively. A porous membrane separates the first and second opposing surfaces, with a liquid electrolyte impregnating the insulating membrane. A gasket formed of a thermoplastic material surrounds the first and second electrodes and seals between the first and second current collector plates for containing the liquid electrolyte.

  18. Conducting effective tailgate trainings.

    PubMed

    Harrington, David; Materna, Barbara; Vannoy, Jim; Scholz, Peter

    2009-07-01

    The California Department of Health Services' Occupational Health Branch and others have identified the construction industry as being at high risk for injuries, illnesses, and fatalities. Effective tailgate trainings (brief job site safety meetings) can be a powerful tool to promote hazard awareness and safe work practices. The authors found that many contractors and supervisors conducted ineffective tailgate trainings. They developed the BuildSafe California Project to assist contractors to have more effective programs by holding 25 training-of-trainers sessions reaching 1,525 participants. The needs assessment, intervention, and evaluation results from the first 18 trainings are presented. Eighty-six percent of the participants found the program "very helpful." Participants used the materials and made improvements in the quality and frequency of trainings. Supervisors must be skilled at conducting tailgate trainings as part of their responsibilities. There is a serious need to provide more culturally appropriate safety training in a workforce increasingly made up of Latino workers. PMID:18372431

  19. Conducting carbonized polyaniline nanotubes

    NASA Astrophysics Data System (ADS)

    Mentus, Slavko; Ćirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 °C min-1 up to a maximum temperature of 800 °C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 µm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 µm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm-1, increased to 0.7 S cm-1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  20. Radiative thermal conduction fronts

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-01-01

    The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence.

  1. Radiative thermal conduction fronts

    NASA Astrophysics Data System (ADS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-07-01

    The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence.

  2. Conduction heat transfer solutions

    SciTech Connect

    VanSant, J.H.

    1980-03-01

    This text is a collection of solutions to a variety of heat conduction problems found in numerous publications, such as textbooks, handbooks, journals, reports, etc. Its purpose is to assemble these solutions into one source that can facilitate the search for a particular problem solution. Generally, it is intended to be a handbook on the subject of heat conduction. This material is useful for engineers, scientists, technologists, and designers of all disciplines, particularly those who design thermal systems or estimate temperatures and heat transfer rates in structures. More than 500 problem solutions and relevant data are tabulated for easy retrieval. There are twelve sections of solutions which correspond with the class of problems found in each. Geometry, state, boundary conditions, and other categories are used to classify the problems. A case number is assigned to each problem for cross-referencing, and also for future reference. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. At least one source reference is given so that the user can review the methods used to derive the solutions. Problem solutions are given in the form of equations, graphs, and tables of data, all of which are also identified by problem case numbers and source references.

  3. Water soluble conductive polymers

    SciTech Connect

    Aldissi, M.

    1989-11-14

    This patent describes polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

  4. Conducting carbonized polyaniline nanotubes.

    PubMed

    Mentus, Slavko; Cirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 degrees C min(-1) up to a maximum temperature of 800 degrees C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 microm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 microm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm(-1), increased to 0.7 S cm(-1) upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy. PMID:19471087

  5. Conductive elastomeric extensometer

    NASA Technical Reports Server (NTRS)

    Gause, R. L.; Glenn, C. G. (Inventor)

    1974-01-01

    An extensometer was used for measuring surface area changes of the human body caused by expansion and contraction of the body. A relatively thin and wide strain responsive conductive elastomeric band was adapted for application to a part of the body, such as around a limb or the trunk of the body. The elastomeric band is incorporated as a resistor in a balanced bridge circuit. Expansion or contraction of the portion of the body on which the elastomeric band is applied causes a change in the resistance of the band and a resultant imbalance of the bridge circuit. The output of the amplifier in volts is suitable for proving the desired reading through a recorder, oscilloscope or voltmeter.

  6. Lateral conduction infrared photodetector

    DOEpatents

    Kim, Jin K.; Carroll, Malcolm S.

    2011-09-20

    A photodetector for detecting infrared light in a wavelength range of 3-25 .mu.m is disclosed. The photodetector has a mesa structure formed from semiconductor layers which include a type-II superlattice formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5. Impurity doped regions are formed on sidewalls of the mesa structure to provide for a lateral conduction of photo-generated carriers which can provide an increased carrier mobility and a reduced surface recombination. An optional bias electrode can be used in the photodetector to control and vary a cut-off wavelength or a depletion width therein. The photodetector can be formed as a single-color or multi-color device, and can also be used to form a focal plane array which is compatible with conventional read-out integrated circuits.

  7. Carbon Fibers Conductivity Studies

    NASA Technical Reports Server (NTRS)

    Yang, C. Y.; Butkus, A. M.

    1980-01-01

    In an attempt to understand the process of electrical conduction in polyacrylonitrile (PAN)-based carbon fibers, calculations were carried out on cluster models of the fiber consisting of carbon, nitrogen, and hydrogen atoms using the modified intermediate neglect of differential overlap (MINDO) molecular orbital (MO) method. The models were developed based on the assumption that PAN carbon fibers obtained with heat treatment temperatures (HTT) below 1000 C retain nitrogen in a graphite-like lattice. For clusters modeling an edge nitrogen site, analysis of the occupied MO's indicated an electron distribution similar to that of graphite. A similar analysis for the somewhat less stable interior nitrogen site revealed a partially localized II electron distribution around the nitrogen atom. The differences in bonding trends and structural stability between edge and interior nitrogen clusters led to a two-step process proposed for nitrogen evolution with increasing HTT.

  8. Ion-conducting membranes

    DOEpatents

    Masel, Richard L.; Chen, Qingmei; Liu, Zengcai; Kutz, Robert

    2016-06-21

    An ion conducting polymeric composition mixture comprises a copolymer of styrene and vinylbenzyl-R.sub.s. R.sub.s is selected from the group consisting of imidazoliums and pyridiniums. The composition contains 10%-90% by weight of vinylbenzyl-R.sub.s. The composition can further comprise a polyolefin comprising substituted polyolefins, a polymer comprising cyclic amine groups, a polymer comprising at least one of a phenylene group and a phenyl group, a polyamide, and/or the reaction product of a constituent having two carbon-carbon double bonds. The composition can be in the form of a membrane. In a preferred embodiment, the membrane is a Helper Membrane that increases the faradaic efficiency of an electrochemical cell into which the membrane is incorporated, and also allows product formation at lower voltages than in cells without the Helper Membrane.

  9. Protein conducting nanopores

    NASA Astrophysics Data System (ADS)

    Harsman, Anke; Krüger, Vivien; Bartsch, Philipp; Honigmann, Alf; Schmidt, Oliver; Rao, Sanjana; Meisinger, Christof; Wagner, Richard

    2010-11-01

    About 50% of the cellular proteins have to be transported into or across cellular membranes. This transport is an essential step in the protein biosynthesis. In eukaryotic cells secretory proteins are transported into the endoplasmic reticulum before they are transported in vesicles to the plasma membrane. Almost all proteins of the endosymbiotic organelles chloroplasts and mitochondria are synthesized on cytosolic ribosomes and posttranslationally imported. Genetic, biochemical and biophysical approaches led to rather detailed knowledge on the composition of the translocon-complexes which catalyze the membrane transport of the preproteins. Comprehensive concepts on the targeting and membrane transport of polypeptides emerged, however little detail on the molecular nature and mechanisms of the protein translocation channels comprising nanopores has been achieved. In this paper we will highlight recent developments of the diverse protein translocation systems and focus particularly on the common biophysical properties and functions of the protein conducting nanopores. We also provide a first analysis of the interaction between the genuine protein conducting nanopore Tom40SC as well as a mutant Tom40SC (\\mathrm {S}_{54} \\to E ) containing an additional negative charge at the channel vestibule and one of its native substrates, CoxIV, a mitochondrial targeting peptide. The polypeptide induced a voltage-dependent increase in the frequency of channel closure of Tom40SC corresponding to a voltage-dependent association rate, which was even more pronounced for the Tom40SC S54E mutant. The corresponding dwelltime reflecting association/transport of the peptide could be determined with \\bar {t}_{\\mathrm {off}} \\cong 1.1 ms for the wildtype, whereas the mutant Tom40SC S54E displayed a biphasic dwelltime distribution (\\bar {t}_{\\mathrm {off}}^1 \\cong 0.4 ms \\bar {t}_{\\mathrm {off}}^2 \\cong 4.6 ms).

  10. Electrical and Thermal Conductivity

    NASA Astrophysics Data System (ADS)

    Ventura, Guglielmo; Perfetti, Mauro

    After a Sect. 1.1 devoted to electrical conductivity and a section that deals with magnetic and dielectric losses ( 1.2 ), this chapter explores the theory of thermal conduction in solids. The examined categories of solids are: metals Sect. 1.3.2 , Dielectrics Sects. 1.3.3 and 1.3.4 and Nanocomposites Sect. 1.3.5 . In Sect. 1.3.6 the problem of thermal and electrical contact between materials is considered because contact resistance occurring at conductor joints in magnets or other high power applications can lead to undesirable electrical losses. At low temperature, thermal contact is also critical in the mounting of temperature sensors, where bad contacts can lead to erroneous results, in particular when superconductivity phenomena are involved.

  11. Conducting Wall Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Goebel, Dan M.; Hofer, Richard R.; Mikellides, Ioannis G.; Katz, Ira; Polk, James E.; Dotson, Brandon

    2013-01-01

    A unique configuration of the magnetic field near the wall of Hall thrusters, called Magnetic Shielding, has recently demonstrated the ability to significantly reduce the erosion of the boron nitride (BN) walls and extend the life of Hall thrusters by orders of magnitude. The ability of magnetic shielding to minimize interactions between the plasma and the discharge chamber walls has for the first time enabled the replacement of insulating walls with conducting materials without loss in thruster performance. The boron nitride rings in the 6 kW H6 Hall thruster were replaced with graphite that self-biased to near the anode potential. The thruster efficiency remained over 60% (within two percent of the baseline BN configuration) with a small decrease in thrust and increase in Isp typical of magnetically shielded Hall thrusters. The graphite wall temperatures decreased significantly compared to both shielded and unshielded BN configurations, leading to the potential for higher power operation. Eliminating ceramic walls makes it simpler and less expensive to fabricate a thruster to survive launch loads, and the graphite discharge chamber radiates more efficiently which increases the power capability of the thruster compared to conventional Hall thruster designs.

  12. Thermal Contact Conductance

    NASA Technical Reports Server (NTRS)

    Salerno, Louis J.; Kittel, Peter

    1997-01-01

    The performance of cryogenic instruments is often a function of their operating temperature. Thus, designers of cryogenic instruments often are required to predict the operating temperature of each instrument they design. This requires accurate thermal models of cryogenic components which include the properties of the materials and assembly techniques used. When components are bolted or otherwise pressed together, a knowledge of the thermal performance of such joints are also needed. In some cases, the temperature drop across these joints represents a significant fraction of the total temperature difference between the instrument and its cooler. While extensive databases exist on the thermal properties of bulk materials, similar databases for pressed contacts do not. This has often lead to instrument designs that avoid pressed contacts or to the over-design of such joints at unnecessary expense. Although many people have made measurements of contact conductances at cryogenic temperatures, this data is often very narrow in scope and even more often it has not been published in an easily retrievable fashion, if published at all. This paper presents a summary of the limited pressed contact data available in the literature.

  13. Electrically Conductive Paints for Satellites

    NASA Technical Reports Server (NTRS)

    Gilligan, J. E.; Wolf, R. E.; Ray, C.

    1977-01-01

    A program was conducted to develop and test electrically conductive paint coatings for spacecraft. A wide variety of organic and inorganic coatings were formulated using conductive binders, conductive pigments, and similar approaches. Z-93, IITRI's standard specification inorganic thermal control coating, exhibits good electrical properties and is a very space-stable coating system. Several coatings based on a conductive pigment (antimony-doped tin oxide) in silicone and silicate binders offer considerable promise. Paint systems using commercially available conductive polymers also appear to be of interest, but will require substantial development. Evaluations were made based on electrical conductivity, paint physical properties, and the stability of spectral reflectance in space environment testing.

  14. Conductive lithium storage electrode

    DOEpatents

    Chiang, Yet-Ming; Chung, Sung-Yoon; Bloking, Jason T.; Andersson, Anna M.

    2008-03-18

    A compound comprising a composition A.sub.x(M'.sub.1-aM''.sub.a).sub.y(XD.sub.4).sub.z, A.sub.x(M'.sub.1-aM''.sub.a).sub.y(DXD.sub.4).sub.z, or A.sub.x(M'.sub.1-aM''.sub.a).sub.y(X.sub.2D.sub.7).sub.z, and have values such that x, plus y(1-a) times a formal valence or valences of M', plus ya times a formal valence or valence of M'', is equal to z times a formal valence of the XD.sub.4, X.sub.2D.sub.7, or DXD.sub.4 group; or a compound comprising a composition (A.sub.1-aM''.sub.a).sub.xM'.sub.y(XD.sub.4).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(DXD.sub.4).sub.z(A.sub.1-aM''.sub.a).s- ub.xM'.sub.y(X.sub.2D.sub.7).sub.z and have values such that (1-a).sub.x plus the quantity ax times the formal valence or valences of M'' plus y times the formal valence or valences of M' is equal to z times the formal valence of the XD.sub.4, X.sub.2D.sub.7 or DXD.sub.4 group. In the compound, A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen, 0.0001conductivity at 27.degree. C. of at least about 10.sup.-8 S/cm. The compound can be a doped lithium phosphate that can intercalate lithium or hydrogen. The compound can be used in an electrochemical device including electrodes and storage batteries and can have a gravimetric capacity of at least about 80 mAh/g while being charged/discharged at greater than about C rate of the compound.

  15. Conductive lithium storage electrode

    DOEpatents

    Chiang, Yet-Ming; Chung, Sung-Yoon; Bloking, Jason T.; Andersson, Anna M.

    2012-04-03

    A compound comprising a composition A.sub.x(M'.sub.1-aM''.sub.a).sub.y(XD.sub.4).sub.z, A.sub.x(M'.sub.1-aM''.sub.a).sub.y(DXD.sub.4).sub.z, or A.sub.x(M'.sub.1-aM''.sub.a).sub.y(X.sub.2D.sub.7).sub.z, and have values such that x, plus y(1-a) times a formal valence or valences of M', plus ya times a formal valence or valence of M'', is equal to z times a formal valence of the XD.sub.4, X.sub.2D.sub.7, or DXD.sub.4 group; or a compound comprising a composition (A.sub.1-aM''.sub.a).sub.xM'.sub.y(XD.sub.4).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(DXD.sub.4).sub.z (A.sub.1-aM''.sub.a).sub.xM'.sub.y(X.sub.2D.sub.7).sub.z and have values such that (1-a).sub.x plus the quantity ax times the formal valence or valences of M'' plus y times the formal valence or valences of M' is equal to z times the formal valence of the XD.sub.4, X.sub.2D.sub.7 or DXD.sub.4 group. In the compound, A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen, 0.0001conductivity at 27.degree. C. of at least about 10.sup.-8 S/cm. The compound can be a doped lithium phosphate that can intercalate lithium or hydrogen. The compound can be used in an electrochemical device including electrodes and storage batteries and can have a gravimetric capacity of at least about 80 mAh/g while being charged/discharged at greater than about C rate of the compound.

  16. Comparing proton conductivity of polymer electrolytes by percent conducting volume

    SciTech Connect

    Kim, Yu Seung; Pivovar, Bryan

    2009-01-01

    Proton conductivity of sulfonated polymers plays a key role in polymer electrolyte membrane fuel cells. Mass based water uptake and ion exchange capacity of sulfonated polymers have been failed to correlating their proton conductivity. In this paper, we report a length scale parameter, percent conductivity volume, which is rather simply obtained from the chemical structure of polymer to compare proton conductivity of wholly aromatic sulfonated polymer perflurosulfonic acid. Morphology effect on proton conductivity at lower RH conditions is discussed using the percent conductivity volume parameter.

  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. Thermal Conductivity of Coated Paper

    SciTech Connect

    Kerr, Lei L; Pan, Yun-Long; Dinwiddie, Ralph Barton; Wang, Hsin; Peterson, Robert C.

    2009-01-01

    In this paper, we introduce a method for measuring the thermal conductivity of paper using a hot disk system. To the best of our knowledge, few publications are found discussing the thermal conductivity of a coated paper although it is important to various forms of today s digital printing where heat is used for imaging as well as for toner fusing. This motivates us to investigate the thermal conductivity of paper coating. Our investigation demonstrates that thermal conductivity is affected by the coat weight and the changes in the thermal conductivity affect ink gloss and density. As the coat weight increases, the thermal conductivity increases. Both the ink gloss and density decrease as the thermal conductivity increases. The ink gloss appears to be more sensitive to the changes in the thermal conductivity.

  19. Thermal Conductivity of Coated Paper

    NASA Astrophysics Data System (ADS)

    Kerr, Lei L.; Pan, Yun-Long; Dinwiddie, Ralph B.; Wang, Hsin; Peterson, Robert C.

    2009-04-01

    In this article, a method for measuring the thermal conductivity of paper using a hot disk system is introduced. To the best of our knowledge, few publications are found discussing the thermal conductivity of a coated paper, although it is important to various forms of today’s digital printing where heat is used for imaging, as well as for toner fusing. This motivated an investigation of the thermal conductivity of paper coating. This study demonstrates that the thermal conductivity is affected by the coating mass and the changes in the thermal conductivity affect toner gloss and density. As the coating mass increases, the thermal conductivity increases. Both the toner gloss and density decrease as the thermal conductivity increases. The toner gloss appears to be more sensitive to the changes in the thermal conductivity.

  20. Nonlinear dynamics in cardiac conduction

    NASA Technical Reports Server (NTRS)

    Kaplan, D. T.; Smith, J. M.; Saxberg, B. E.; Cohen, R. J.

    1988-01-01

    Electrical conduction in the heart shows many phenomena familiar from nonlinear dynamics. Among these phenomena are multiple basins of attraction, phase locking, and perhaps period-doubling bifurcations and chaos. We describe a simple cellular-automation model of electrical conduction which simulates normal conduction patterns in the heart as well as a wide range of disturbances of heart rhythm. In addition, we review the application of percolation theory to the analysis of the development of complex, self-sustaining conduction patterns.

  1. Rapid prototype extruded conductive pathways

    DOEpatents

    Bobbitt, III, John T.

    2016-06-21

    A process of producing electrically conductive pathways within additively manufactured parts and similar parts made by plastic extrusion nozzles. The process allows for a three-dimensional part having both conductive and non-conductive portions and allows for such parts to be manufactured in a single production step.

  2. A Simple Audio Conductivity Device.

    ERIC Educational Resources Information Center

    Berenato, Gregory; Maynard, David F.

    1997-01-01

    Describes a simple audio conductivity device built to address the problem of the lack of sensitivity needed to measure small differences in conductivity in crude conductivity devices. Uses a 9-V battery as a power supply and allows the relative resistance differences between substances to be detected by the frequency of its audible tones. Presents…

  3. Conductive nanomaterials for printed electronics.

    PubMed

    Kamyshny, Alexander; Magdassi, Shlomo

    2014-09-10

    This is a review on recent developments in the field of conductive nanomaterials and their application in printed electronics, with particular emphasis on inkjet printing of ink formulations based on metal nanoparticles, carbon nanotubes, and graphene sheets. The review describes the basic properties of conductive nanomaterials suitable for printed electronics (metal nanoparticles, carbon nanotubes, and graphene), their stabilization in dispersions, formulations of conductive inks, and obtaining conductive patterns by using various sintering methods. Applications of conductive nanomaterials for electronic devices (transparent electrodes, metallization of solar cells, RFID antennas, TFTs, and light emitting devices) are also briefly reviewed. PMID:25340186

  4. Temperature dependence of conductivity measurement for conducting polymer

    NASA Astrophysics Data System (ADS)

    Gutierrez, Leandro; Duran, Jesus; Isah, Anne; Albers, Patrick; McDougall, Michael; Wang, Weining

    2014-03-01

    Conducting polymer-based solar cells are the newest generation solar cells. While research on this area has been progressing, the efficiency is still low because certain important parameters of the solar cell are still not well understood. It is of interest to study the temperature dependence of the solar cell parameters, such as conductivity of the polymer, open circuit voltage, and reverse saturation current to gain a better understanding on the solar cells. In this work, we report our temperature dependence of conductivity measurement using our in-house temperature-varying apparatus. In this project, we designed and built a temperature varying apparatus using a thermoelectric cooler module which gives enough temperature range as we need and costs much less than a cryostat. The set-up of the apparatus will be discussed. Temperature dependence of conductivity measurements for PEDOT:PSS films with different room-temperature conductivity will be compared and discussed. NJSGC-NASA Fellowship grant

  5. Thermal conductivity of boron carbides

    NASA Technical Reports Server (NTRS)

    Wood, C.; Emin, D.; Gray, P. E.

    1985-01-01

    Knowledge of the thermal conductivity of boron carbide is necessary to evaluate its potential for high-temperature thermoelectric energy conversion applications. Measurements have been conducted of the thermal diffusivity of hot-pressed boron carbide BxC samples as a function of composition (x in the range from 4 to 9), temperature (300-1700 K), and temperature cycling. These data, in concert with density and specific-heat data, yield the thermal conductivities of these materials. The results are discussed in terms of a structural model that has been previously advanced to explain the electronic transport data. Some novel mechanisms for thermal conduction are briefly discussed.

  6. Thermal conductivity Measurements of Kaolite

    SciTech Connect

    Wang, H

    2003-02-21

    Testing was performed to determine the thermal conductivity of Kaolite 1600, which primarily consists of Portland cement and vermiculite. The material was made by Thermal Ceramics for refractory applications. Its combination of light weight, low density, low cost, and noncombustibility made it an attractive alternative to the materials currently used in ES-2 container for radioactive materials. Mechanical properties and energy absorption tests of the Kaolite have been conducted at the Y-12 complex. Heat transfer is also an important factor for the application of the material. The Kaolite samples are porous and trap moisture after extended storage. Thermal conductivity changes as a function of moisture content below 100 C. Thermal conductivity of the Kaolite at high temperatures (up to 700 C) are not available in the literature. There are no standard thermal conductivity values for Kaolite because each sample is somewhat different. Therefore, it is necessary to measure thermal conductivity of each type of Kaolite. Thermal conductivity measurements will help the modeling and calculation of temperatures of the ES-2 containers. This report focuses on the thermal conductivity testing effort at ORNL.

  7. The Teacher and Immoral Conduct.

    ERIC Educational Resources Information Center

    Rich, John Martin

    1986-01-01

    This article examines changes in community and legal attitudes towards immoral conduct by teachers. The concept of immorality is clarified in order to discuss different sources of immoral conduct. The study of professional ethics as part of teacher preparation is advocated. (MT)

  8. 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.

  9. Bone-Conduction ABR Tests.

    ERIC Educational Resources Information Center

    Cone-Wesson, Barbara

    1995-01-01

    This article discusses the accuracy of bone-conduction auditory brainstem response (BC-ABR) tests to determine the presence and severity of conductive hearing impairment. It provides warnings about technical pitfalls and recommends incorporating BC-ABR protocols for routine clinical use. It concludes that the method allows estimating cochlear…

  10. Conductive polymer-based material

    DOEpatents

    McDonald, William F.; Koren, Amy B.; Dourado, Sunil K.; Dulebohn, Joel I.; Hanchar, Robert J.

    2007-04-17

    Disclosed are polymer-based coatings and materials comprising (i) a polymeric composition including a polymer having side chains along a backbone forming the polymer, at least two of the side chains being substituted with a heteroatom selected from oxygen, nitrogen, sulfur, and phosphorus and combinations thereof; and (ii) a plurality of metal species distributed within the polymer. At least a portion of the heteroatoms may form part of a chelation complex with some or all of the metal species. In many embodiments, the metal species are present in a sufficient concentration to provide a conductive material, e.g., as a conductive coating on a substrate. The conductive materials may be useful as the thin film conducting or semi-conducting layers in organic electronic devices such as organic electroluminescent devices and organic thin film transistors.

  11. Conductivity-limiting bipolar thermal conductivity in semiconductors

    PubMed Central

    Wang, Shanyu; Yang, Jiong; Toll, Trevor; Yang, Jihui; Zhang, Wenqing; Tang, Xinfeng

    2015-01-01

    Intriguing experimental results raised the question about the fundamental mechanisms governing the electron-hole coupling induced bipolar thermal conduction in semiconductors. Our combined theoretical analysis and experimental measurements show that in semiconductors bipolar thermal transport is in general a “conductivity-limiting” phenomenon, and it is thus controlled by the carrier mobility ratio and by the minority carrier partial electrical conductivity for the intrinsic and extrinsic cases, respectively. Our numerical method quantifies the role of electronic band structure and carrier scattering mechanisms. We have successfully demonstrated bipolar thermal conductivity reduction in doped semiconductors via electronic band structure modulation and/or preferential minority carrier scatterings. We expect this study to be beneficial to the current interests in optimizing thermoelectric properties of narrow gap semiconductors. PMID:25970560

  12. Conductivity-limiting bipolar thermal conductivity in semiconductors.

    PubMed

    Wang, Shanyu; Yang, Jiong; Toll, Trevor; Yang, Jihui; Zhang, Wenqing; Tang, Xinfeng

    2015-01-01

    Intriguing experimental results raised the question about the fundamental mechanisms governing the electron-hole coupling induced bipolar thermal conduction in semiconductors. Our combined theoretical analysis and experimental measurements show that in semiconductors bipolar thermal transport is in general a "conductivity-limiting" phenomenon, and it is thus controlled by the carrier mobility ratio and by the minority carrier partial electrical conductivity for the intrinsic and extrinsic cases, respectively. Our numerical method quantifies the role of electronic band structure and carrier scattering mechanisms. We have successfully demonstrated bipolar thermal conductivity reduction in doped semiconductors via electronic band structure modulation and/or preferential minority carrier scatterings. We expect this study to be beneficial to the current interests in optimizing thermoelectric properties of narrow gap semiconductors. PMID:25970560

  13. Effects of compatability on the conductivity of conducting polymer blends

    SciTech Connect

    Liu, Mingjun; Nowak, C.K.; Gregory, R.V.

    1995-12-01

    The electrical conductivity of chemically synthesized polyaniline (PANI) blends with nylon 6,6 and polystyrene was measured. The conductivities of the top and bottom of the films cast from blend solutions were found to differ. This effect was most pronounced at low percent loadings of PANI. The maximum difference in conductivity between two sides of the same film was found to be five orders of magnitude in the case of a 5% PANI blend with polystyrene. In this case the conductive polymer appears to be rich on one side of the film rather than more homogeneously dispersed on both sides. SEM provides evidence for the formation of a percolation cluster on one side of the film which is most notable in polystyrene blends. X-ray and FTIR indicated that greater interaction between PANI and nylon 6,6 than PANI and polystyrene. It is proposed that the magnitude of the variation in conductivity between the two sides of the film depends on the compatibility of the conducting and insulating host polymers.

  14. 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.

  15. Thermal conductivity of nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    Cahill, David; Putnam, Shawn

    2006-03-01

    We present our experimental study on the thermal conductivity of nanofluids loaded with small volume fractions of C60-C70 fullerenes and alkanethiolate-protected Au nanoparticles. We use an optical beam deflection technique that measures the thermal diffusivity of fluid mixtures and suspensions of nanoparticles with a precision of better than 1%. Our approach is tested using the thermal conductivity of ethanol-water mixtures; in nearly pure ethanol, the increase in thermal conductivity with water concentration is a factor of two larger than predicted by effective medium theory. The solutions of the C60-C70 fullerenes and the alkanethiolate-protected Au nanoparticles were measured to maximum volume fractions of 0.6% and 0.35 vol%, respectively. We do not observe anomalous enhancements of the thermal conductivity that have been reported in previous studies of nanofluids; the largest increase in thermal conductivity we have observed is 1.3 ±0.8% for 4 nm diameter Au particles suspended in ethanol. However, within the context of effective medium theory, these findings are expected: effective medium theory predicts that the largest possible increase in the thermal conductivity of a fluid loaded by a volume fraction φ1 of spherical particles will be 3φλ0, where λ0 is the thermal conductivity of the carrier fluid.

  16. Stratospheric conductivity variations over thunderstorms

    NASA Technical Reports Server (NTRS)

    Holzworth, R. H.; Norville, K. W.; Kintner, P. M.; Powell, S. P.

    1986-01-01

    This paper reports the first in-situ observation of variations in the electrical conductivity over thunderstorms at 26 km altitude. The vector electric field, positive and negative polar conductivity, and optical lightning power/flash were measured by payloads on superpressure balloons in the Southern Hemisphere in early 1984. It is found that in 72 percent of the thunderstorm periods observed (or in 23 of 32 periods) there were clear cases of conductivity variations while the balloons were over the thunderstorms. Examples from two separate balloons at widely separated dates and locations showing both daytime and nighttime events are presented. The conductivity measurements are made with the relaxation technique, and the vector field measurements are based on the double Langmuir probe high-impedance method. It is found that the positive and negative conductivity measurements vary independently and have a different temporal profile than the dc electric field. The polar conductivity variations can exceed a factor of 2 at this altitude. In seven of the nine most intense thunderstorm events the total conductivity increased, while in only one of these nine events did it decrease (one event had no change). Implications of these observations for global current patterns are discussed.

  17. Edge conduction in vacuum glazing

    SciTech Connect

    Simko, T.M.; Collins, R.E.; Beck, F.A.; Arasteh, D.

    1995-03-01

    Vacuum glazing is a form of low-conductance double glazing using in internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. An array of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation. Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge effects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.

  18. Thermal Conductances Of Metal Contacts

    NASA Technical Reports Server (NTRS)

    Salerno, L. J.; Kittel, P.; Scherkenbach, F. E.; Spivak, A. L.

    1988-01-01

    Report presents results of measurements of thermal conductances of aluminum and stainless-steel contacts at temperatures from 1.6 to 6.0 K. Measurement apparatus includes gearmotor assembly connected to rocker arm by music wire to load sample pair with forces up to 670 N. Heater placed above upper sample. Germanium resistance thermometers in upper and lower samples measured temperature difference across interface over range of heater powers from 0.1 to 10.0 mW. The thermal conductance calculated from temperature difference. Measurements provide data for prediction of thermal conductances of bolted joints in cryogenic infrared instruments.

  19. Variable conductance heat pipe technology

    NASA Technical Reports Server (NTRS)

    Marcus, B. D.; Edwards, D. K.; Anderson, W. T.

    1973-01-01

    Research and development programs in variable conductance heat pipe technology were conducted. The treatment has been comprehensive, involving theoretical and/or experimental studies in hydrostatics, hydrodynamics, heat transfer into and out of the pipe, fluid selection, and materials compatibility, in addition to the principal subject of variable conductance control techniques. Efforts were not limited to analytical work and laboratory experimentation, but extended to the development, fabrication and test of spacecraft hardware, culminating in the successful flight of the Ames Heat Pipe Experiment on the OAO-C spacecraft.

  20. Conduction of Electricity through Gases

    NASA Astrophysics Data System (ADS)

    Thomson, J. J.; Thomson, G. P.

    2013-06-01

    1. Electrical conductivity of gases in a normal state; 2. Properties of a gas when in a conducting state; 3. Mobility of ions; 4. Mathematical theory of the conduction of electricity through a gas containing ions; 5. Effect produced by a magnetic field on the motion of the ions; 6. Determination of the ratio of the charge to the mass of an ion; 7. Determination of the charge carried by the negative ion; 8. On some physical properties of gaseous ions; 9. Ionisation by incandescent solids; 10. Ionisation in gases from flames; 11. Ionisation by light. Photo-electric effects; Name index; Subject index.

  1. Lightweight, Thermally Conductive Composite Material

    NASA Technical Reports Server (NTRS)

    Sharp, G. Richard; Loftin, Timothy A.

    1990-01-01

    Aluminum reinforced with carbon fibers superior to copper in some respects. Lightweight composite material has high thermal conductivity. Consists of aluminum matrix containing graphite fibers, all oriented in same direction. Available as sheets, tubes, and bars. Thermal conductivity of composite along fibers rises above that of pure copper over substantial range of temperatures. Graphite/aluminum composite useful in variety of heat-transfer applications in which reduction of weight critical. Used to conduct heat in high-density, high-speed integrated-circuit packages for computers and in base plates for electronic equipment. Also used to carry heat away from leading edges of wings in high-speed airplanes.

  2. Electrically conductive and thermally conductive materials for electronic packaging

    NASA Astrophysics Data System (ADS)

    Liu, Zongrong

    The aim of this dissertation is to develop electrically or thermally conductive materials that are needed for electronic packaging and microelectronic cooling. These materials are in the form of coatings and are made from pastes. The research work encompasses paste formulation, studying the process of converting a paste to a conductive material, relating the processing conditions to the structure and performance, and evaluating performance attributes that are relevant to the application of these conductive materials. The research has resulted in new information that is valuable to the microelectronic industry. Work on electrically conductive materials emphasizes the development of electrical interconnection materials in the form of air-firable glass-free silver-based electrically conductive thick films, which use the Ti-Al alloy as the binder and are in contrast to conventional films that use glass as the binder. The air-firability, as enabled by minor additions of tin and zinc to the paste, is in contrast to previous glass-free films that are not firable. The recommended firing condition is 930°C in air. The organic vehicle in the paste comprises ethyl cellulose, which undergoes thermal decomposition during burnout of the paste. The ethyl cellulose is dissolved in ether, which facilitates the burnout. Excessive ethyl cellulose hinders the burnout. A higher heating rate results in more residue after burnout. The presence of silver particles facilitates drying and burnout. Firing in air gives lower resistivity than firing in oxygen. Firing in argon gives poor films. Compared to conventional films that use glass as the binder, these films, when appropriately fired, exhibit lower electrical resistivity (2.5 x 10-6 O.cm) and higher scratch resistance. Work on thermally conductive materials addresses thermal interface materials, which are materials placed at the interface between a heat sink and a heat source for the purpose of improving the thermal contact. Heat

  3. 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.

  4. Conductivity of continuum percolating systems

    NASA Astrophysics Data System (ADS)

    Stenull, Olaf; Janssen, Hans-Karl

    2001-11-01

    We study the conductivity of a class of disordered continuum systems represented by the Swiss-cheese model, where the conducting medium is the space between randomly placed spherical holes, near the percolation threshold. This model can be mapped onto a bond percolation model where the conductance σ of randomly occupied bonds is drawn from a probability distribution of the form σ-a. Employing the methods of renormalized field theory we show to arbitrary order in ɛ expansion that the critical conductivity exponent of the Swiss-cheese model is given by tSC(a)=(d-2)ν+max[φ,(1-a)-1], where d is the spatial dimension and ν and φ denote the critical exponents for the percolation correlation length and resistance, respectively. Our result confirms a conjecture that is based on the ``nodes, links, and blobs'' picture of percolation clusters.

  5. Thermal conductivity of nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    Putnam, Shawn A.; Cahill, David G.; Braun, Paul V.; Ge, Zhenbin; Shimmin, Robert G.

    2006-04-01

    We describe an optical beam deflection technique for measurements of the thermal diffusivity of fluid mixtures and suspensions of nanoparticles with a precision of better than 1%. Our approach is tested using the thermal conductivity of ethanol-water mixtures; in nearly pure ethanol, the increase in thermal conductivity with water concentration is a factor of 2 larger than predicted by effective medium theory. Solutions of C60-C70 fullerenes in toluene and suspensions of alkanethiolate-protected Au nanoparticles were measured to maximum volume fractions of 0.6% and 0.35 vol %, respectively. We do not observe anomalous enhancements of the thermal conductivity that have been reported in previous studies of nanofluids; the largest increase in thermal conductivity we have observed is 1.3%+/-0.8% for 4 nm diam Au particles suspended in ethanol.

  6. Shape memory thermal conduction switch

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, Rajan (Inventor); Krishnan, Vinu (Inventor); Notardonato, William U. (Inventor)

    2010-01-01

    A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

  7. Psychobiological Basis of Conduct Disorder.

    ERIC Educational Resources Information Center

    Shapiro, Steven K.; Hynd, George W.

    1993-01-01

    Examines psychobiological literature pertaining to conduct disorder (CD), with particular emphasis on how such information can increase understanding of youths representing undersocialized aggressive subtype of CD. Reviews literature from neuroanatomical, biochemical, psychophysiological, and pharmacological arenas. Outlines theoretical framework…

  8. Magneto-inductive conductivity sensor

    NASA Astrophysics Data System (ADS)

    Floume, Timmy

    2011-12-01

    Multi-element inductive coil systems are used to measure locally resolved conductivity profile. Usually such sensors rely on the separate interrogation of each coil. In addition, the coils must generally be magnetically decoupled for accurate signal processing. Here we demonstrate a metamaterial conductivity sensor that uses broadband interrogation of a line of coupled resonators. No decoupling is needed, which allows a transmission measurement to be carried out. The resonant elements of the metamaterial are coupled with each other and their neighbourhood which affects their quality factor. We derive analytically an algorithm to extract the local perturbation in each element from the modal measurement. We investigate numerically the performance of the sensor and derive an optimal configuration in terms of nearest neighbour coupling and the initial non-uniformity. Finally we implement a four-element magneto inductive conductivity sensor and show that a conductive perturbation along the line can be accurately reconstructed. Generalisation to higher number of elements is also discussed.

  9. Conductivity of a relativistic plasma

    SciTech Connect

    Braams, B.J.; Karney, C.F.F.

    1989-03-01

    The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab.

  10. RF hyperthermia using conductive nanoparticles

    NASA Astrophysics Data System (ADS)

    Gach, H. Michael; Balachandrasekaran, Arvind; Nair, Tejas

    2010-02-01

    Specific absorption rate (SAR) heating using radiofrequency (RF) waves is affected by the RF frequency and amplitude, and the conductivity of the tissue. Recently, conductive nanoparticles were demonstrated to induce hyperthermia in vitro and in vivo upon irradiation with an external 13.56 MHz RF field. The addition of conductive nanoparticles was assumed to increase the tissue conductivity and SAR. However, no quantitative studies have been performed that characterize the conductivities of biocompatible colloids or tissues containing nanoparticles, and relate the conductivity to SAR. The complex permittivities were measured for colloids containing single-wall carbon nanotubes (SWCNTs) in normal saline with 0.32% w/v Pluronic F108 nonionic surfactant. The carbon concentrations of the colloids ranged from 0 to 88 mM. The permittivities were measured using a dielectric probe and RF network analyzer for RF frequencies from 200 MHz to 3 GHz. The nonionic surfactant was added to the colloids to minimize flocculation of the nanotubes during the RF heating experiments. The results were compared with prior measurements of colloids containing 0.02% Pluronic F108. The dielectric and conductivity of the 0.02% Pluronic colloids rose linearly with carbon concentration but the 0.32% Pluronic colloids varied from linearity. Based on the permittivity results, selected colloid samples were placed inside a Bruker 7T/20 magnetic resonance (MR) imaging (MRI) system and irradiated at 300 MHz using a high duty cycle RF pulse sequence. The temperature changes were measured directly using fiber-optic thermometers and indirectly using MR thermometry and spectroscopy. Temperature changes were consistent with the colloid conductivities.

  11. Electrical conduction in polymer dielectrics

    NASA Technical Reports Server (NTRS)

    Cotts, D. B.

    1985-01-01

    The use of polymer dielectrics with moderate resistivities could reduce or eliminate problems associated with spacecraft charging. The processes responsible for conduction and the properties of electroactive polymers are reviewed, and correlations drawn between molecular structure and electrical conductivity. These structure-property relationships led to the development of several new electroactive polymer compositions and the identification of several systems that have the requisite thermal, mechanical, environmental and electrical properties for use in spacecraft.

  12. Nonlinear heat conduction with combustion

    SciTech Connect

    Galaktionov, V.A.; Kurclyumov, S.P.; Samarskiv, A.A. )

    1991-01-01

    This paper deals with a study of the properties of high-intensity combustion of a solid nonlinear heat conducting medium which is described by the quasilinear parabolic-type equation for nonlinear heat conduction with a source. The paper summarizes a significant range of investigations dealing with the study of high-intensity thermal processes in solid nonlinear media carried out by the authors in the past decade.

  13. Highly elastic conductive polymeric MEMS

    NASA Astrophysics Data System (ADS)

    Ruhhammer, J.; Zens, M.; Goldschmidtboeing, F.; Seifert, A.; Woias, P.

    2015-02-01

    Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations.

  14. Thermal conductivity of cane fiberboard

    SciTech Connect

    Leader, D.R.

    1995-05-01

    The thermal conductivity of cane fiberboard was measured in two planes; parallel to the surface and perpendicular to the surface of the manufactured sheet. The information was necessary to better understand the thermal response of a loaded shipping container. The tests demonstrated that the thermal conductivity of cane fiberboard in the plane parallel to the surface of the sheet was nearly twice as great as the conductivity of the same material in a plane perpendicular to the sheet. There was no significant difference in the conductivity in different directions within the plane parallel to the surface, and the presence of glue between layers of fiberboard did not significantly change the conductivity of the assembly. The tests revealed that the thermal conductivity measured in a direction perpendicular to the plane of the surface of a stack of cane fiberboard sheets not bonded together, decreases with an increase in the mean temperature. This was determined to be the result of air gaps between the sheets of fiberboard, and not related to the properties of the material itself

  15. Conductivity in transparent oxide semiconductors

    NASA Astrophysics Data System (ADS)

    King, P. D. C.; Veal, T. D.

    2011-08-01

    Despite an extensive research effort for over 60 years, an understanding of the origins of conductivity in wide band gap transparent conducting oxide (TCO) semiconductors remains elusive. While TCOs have already found widespread use in device applications requiring a transparent contact, there are currently enormous efforts to (i) increase the conductivity of existing materials, (ii) identify suitable alternatives, and (iii) attempt to gain semiconductor-engineering levels of control over their carrier density, essential for the incorporation of TCOs into a new generation of multifunctional transparent electronic devices. These efforts, however, are dependent on a microscopic identification of the defects and impurities leading to the high unintentional carrier densities present in these materials. Here, we review recent developments towards such an understanding. While oxygen vacancies are commonly assumed to be the source of the conductivity, there is increasing evidence that this is not a sufficient mechanism to explain the total measured carrier concentrations. In fact, many studies suggest that oxygen vacancies are deep, rather than shallow, donors, and their abundance in as-grown material is also debated. We discuss other potential contributions to the conductivity in TCOs, including other native defects, their complexes, and in particular hydrogen impurities. Convincing theoretical and experimental evidence is presented for the donor nature of hydrogen across a range of TCO materials, and while its stability and the role of interstitial versus substitutional species are still somewhat open questions, it is one of the leading contenders for yielding unintentional conductivity in TCOs. We also review recent work indicating that the surfaces of TCOs can support very high carrier densities, opposite to the case for conventional semiconductors. In thin-film materials/devices and, in particular, nanostructures, the surface can have a large impact on the total

  16. Synthesis and characterization of soluble conducting polymers and conducting adhesives

    NASA Astrophysics Data System (ADS)

    Oztemiz, Serhan

    With the demanding nature of the technology today, scientists are looking for new materials in order to decrease the cost, increase the efficiency of the use of the materials, and decrease time-consuming steps in order to increase the speed of production. New materials are being studied to decrease the weight of cars, planes and space vehicles; surface properties are being modified to decrease the drag coefficient; new technologies are being introduced for speeding up applications in production and assembly lines. In this research we address the needs of different technological applications from a conductivity perspective. In the first part of the thesis, the synthesis of soluble conducting polymers in order to make them more processable for potential electronic and photovoltaic applications is presented. Soluble conducting polymers of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene and 3-dodecylthiophene were synthesized electrochemically and thus, doped during synthesis. It was found that the conductivities; molecular weights and degrees of polymerization of the polymers strongly depend on the side chain's length. The substitution of alkyl side chains decreases the reactivity of the growing chain, and with an increasing side-chain length, all of these properties show a decrease. The hexyl substituent, being the shortest of the four side chains, causes the least distortion in the background, has the highest conjugation, and has the highest shift in the UV spectrum when it polymerizes. As the length of the side chain increases, the shift in the UV spectrum decreases, too. Decrease in the pi-stacking, conjugation and delocalization decreases the conductivity. This gives the material an opportunity to be used in photovoltaic applications. In the second part of the thesis, a conducting adhesive formulation that eliminates the need for heat or other expensive and rather bothersome application methods to activate the adhesive is investigated. Using the quick

  17. Quantum Conductance in Metal Nanowires

    NASA Astrophysics Data System (ADS)

    Ugarte, Daniel

    2004-03-01

    Quantum Conductance in Metal Nanowires D. Ugarte Brazilian National Synchrotron Light Laboratory C.P. 6192, 13084-971 Campinas SP, Brazil. Electrical transport properties of metallic nanowires (NWs) have received great attention due to their quantum conductance behavior. Atomic scale wires can be generated by stretching metal contacts; during the elongation and just before rupture, the NW conductance shows flat plateaus and abrupt jumps of approximately a conductance quantum. In this experiments, both the NW atomic arrangement and conductance change simultaneously, making difficult to discriminate electronic and structural effects. In this work, the atomic structure of NWs was studied by time-resolved in situ experiments in a high resolution transmission electron microscope, while their electrical properties using an UHV mechanically controllable break junction (MCBJ). From the analysis of numerous HRTEM images and videos, we have deduced that metal (Au, Ag, Pt, etc.) junctions generated by tensile deformation are crystalline and free of defects. The neck structure is strongly dependent on the surface properties of the analyzed metal, this was verified by comparing different metal NWs (Au, Ag, Cu), which have similar atomic structure (FCC), but show very different faceting patterns. The correlation between the observed structural and transport properties of NW points out that the quantum conductance behavior is defined by preferred atomic arrangement at the narrowest constriction. In the case of magnetic (ex. Fe,Co,Ni) or quasi-magnetic (ex. Pd) wires, we have observed that one-atom-thick structures show a conductance of half the quantum as expected for a fully spin polarized current. This phenomenon seems to occur spontaneously for magnetic suspended atom-chains in zero magnetic field and at room temperature. These results open new opportunities for spin control in nanostructures. Funded by FAPESP, LNLS and CNPq.

  18. Conformational gating of DNA conductance

    PubMed Central

    Artés, Juan Manuel; Li, Yuanhui; Qi, Jianqing; Anantram, M. P.; Hihath, Joshua

    2015-01-01

    DNA is a promising molecule for applications in molecular electronics because of its unique electronic and self-assembly properties. Here we report that the conductance of DNA duplexes increases by approximately one order of magnitude when its conformation is changed from the B-form to the A-form. This large conductance increase is fully reversible, and by controlling the chemical environment, the conductance can be repeatedly switched between the two values. The conductance of the two conformations displays weak length dependencies, as is expected for guanine-rich sequences, and can be fit with a coherence-corrected hopping model. These results are supported by ab initio electronic structure calculations that indicate that the highest occupied molecular orbital is more disperse in the A-form DNA case. These results demonstrate that DNA can behave as a promising molecular switch for molecular electronics applications and also provide additional insights into the huge dispersion of DNA conductance values found in the literature. PMID:26648400

  19. Thermal conductivity of carbonate rocks

    USGS Publications Warehouse

    Thomas, J., Jr.; Frost, R.R.; Harvey, R.D.

    1973-01-01

    The thermal conductivities of several well-defined carbonate rocks were determined near 40??C. Values range from 1.2 W m-1 C-1 for a highly porous chalk to 5.1 W m-1 C-1 for a dolomite. The thermal conductivity of magnesite (5.0) is at the high end of the range, and that for Iceland Spar Calcite (3.2) is near the middle. The values for limestones decrease linearly with increasing porosity. Dolomites of comparable porosity have greater thermal conductivities than limestones. Water-sorbed samples have expected greater thermal conductivities than air-saturated (dry) samples of the same rock. An anomalously large increase in the thermal conductivity of a water-sorbed clayey dolomite over that of the same sample when dry is attributed to the clay fraction, which swells during water inhibition, causing more solid-to-solid contacts within the dolomite framework. Measurements were made with a Colora Thermoconductometer. Chemical and mineralogical analyses were made and tabulated. Porosity of the rocks was determined by mercury porosimetry and also from density measurements. The Iceland Spar Calcite and magnesite were included for reference. ?? 1973.

  20. Thermal Conductivity in Supercooled Water

    NASA Astrophysics Data System (ADS)

    Biddle, John; Holten, Vincent; Sengers, Jan; Anisimov, Mikhail

    2013-03-01

    The heat capacity of supercooled water, measured down to -37 C, shows an anomalous increase as temperature decreases. The thermal diffusivity, the ratio of thermal conductivity and the heat capacity per unit volume, shows a decrease. These anomalies may be associated with a hypothetical liquid-liquid critical point in metastable water below the line of homogeneous nucleation. The data suggest that the thermal conductivity does not show a significant critical enhancement, in contrast to what is observed near the vapor-liquid critical point. We have used mode-coupling theory to investigate the possible effect of critical fluctuations on the thermal conductivity of supercooled water, and shown that indeed this effect would be too small to be measurable at experimentally accessible temperatures. We discuss physical reasons for the striking difference between the vapor-liquid and liquid-liquid critical enhancements of thermal conductivity in water. We also discuss the discrepancy between the thermal conductivity calculated from experimental data and that obtained by computer simulations of the TIP5P water-like model. American Chemical Society Petroleum Research Fund Grant No. 52666-ND6

  1. Conformational gating of DNA conductance.

    PubMed

    Artés, Juan Manuel; Li, Yuanhui; Qi, Jianqing; Anantram, M P; Hihath, Joshua

    2015-01-01

    DNA is a promising molecule for applications in molecular electronics because of its unique electronic and self-assembly properties. Here we report that the conductance of DNA duplexes increases by approximately one order of magnitude when its conformation is changed from the B-form to the A-form. This large conductance increase is fully reversible, and by controlling the chemical environment, the conductance can be repeatedly switched between the two values. The conductance of the two conformations displays weak length dependencies, as is expected for guanine-rich sequences, and can be fit with a coherence-corrected hopping model. These results are supported by ab initio electronic structure calculations that indicate that the highest occupied molecular orbital is more disperse in the A-form DNA case. These results demonstrate that DNA can behave as a promising molecular switch for molecular electronics applications and also provide additional insights into the huge dispersion of DNA conductance values found in the literature. PMID:26648400

  2. Universal Optical Conductance of Graphite

    SciTech Connect

    Kuzmenko, A. B.; Heumen, E. van; Carbone, F.; Marel, D. van der

    2008-03-21

    We find experimentally that the optical sheet conductance of graphite per graphene layer is very close to ({pi}/2)e{sup 2}/h, which is the theoretically expected value of dynamical conductance of isolated monolayer graphene. Our calculations within the Slonczewski-Weiss-McClure model explain well why the interplane hopping leaves the conductance of graphene sheets in graphite almost unchanged for photon energies between 0.1 and 0.6 eV, even though it significantly affects the band structure on the same energy scale. The f-sum rule analysis shows that the large increase of the Drude spectral weight as a function of temperature is at the expense of the removed low-energy optical spectral weight of transitions between hole and electron bands.

  3. Optical conductivity of curved graphene.

    PubMed

    Chaves, A J; Frederico, T; Oliveira, O; de Paula, W; Santos, M C

    2014-05-01

    We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an enhancement of the optical conductivity peaks in the region of the far- and mid-infrared frequencies for periodicities ∼100 nm. The width and position of the peaks can be changed by dialling the parameters of the deformation profiles. The enhancement of the optical conductivity is due to intraband transitions and the translational invariance breaking in the geometrically deformed background. Furthermore, we derive an analytical solution of the Dirac equation in a curved space for a general deformation along one spatial direction. For this class of geometries, it is shown that curvature induces an extra phase in the electron wave function, which can also be explored to produce interference devices of the Aharonov-Bohm type. PMID:24759188

  4. Temperature correction in conductivity measurements

    USGS Publications Warehouse

    Smith, Stanford H.

    1962-01-01

    Electrical conductivity has been widely used in freshwater research but usual methods employed by limnologists for converting measurements to conductance at a given temperature have not given uniformly accurate results. The temperature coefficient used to adjust conductivity of natural waters to a given temperature varies depending on the kinds and concentrations of electrolytes, the temperature at the time of measurement, and the temperature to which measurements are being adjusted. The temperature coefficient was found to differ for various lake and stream waters, and showed seasonal changes. High precision can be obtained only by determining temperature coefficients for each water studied. Mean temperature coefficients are given for various temperature ranges that may be used where less precision is required.

  5. Optical conductivity for liquid semiconductors

    NASA Astrophysics Data System (ADS)

    Jain, Manish; Ko, Eunjung; Derby, J. J.; Chelikowsky, James

    2002-03-01

    We present calculations for the optical conductivity of several semiconductor liquids: SiGe, GaAs, CdTe, and ZnTe. We perform ab initio molecular dynamics for these liquids. The required interatomic forces are determined using the pseudopotential density functional method. We determine the optical conductivity by considering ensemble averages of the liquid state within the Kubo-Greenwood formalism. In the liquid phase, CdTe and ZnTe exhibit properties that are different from III-V and group IV semiconductors. CdTe and ZnTe remain semiconducting unlike SiGe and GaAs, which are metallic in the melt. These differences in optical conductivities are explained in terms of differences in the microstructure of the liquids. We also verify an empirical rule by Joffe and Regel. Their rule predicts the liquid will remain semiconducting if the short range order of the melt resembles that of the crystalline phase.

  6. Quantized ionic conductance in nanopores

    SciTech Connect

    Zwolak, Michael; Lagerqvist, Johan; Di Ventra, Massimilliano

    2009-01-01

    Ionic transport in nanopores is a fundamentally and technologically important problem in view of its ubiquitous occurrence in biological processes and its impact on DNA sequencing applications. Using microscopic calculations, we show that ion transport may exhibit strong non-liDearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. Once in the pore, the water molecules form wavelike structures due to multiple scattering at the surface of the pore walls and interference with the radial waves around the ion. We discuss these effects as well as the conditions under which the step-like features in the ionic conductance should be experimentally observable.

  7. Conductive mechanism in manganite materials

    NASA Astrophysics Data System (ADS)

    Liu, Xianming; Zhu, Hong; Zhang, Yuheng

    2002-01-01

    We describe a model in which f(T)=M(T)/Mmax represents both the fraction of the itinerant electron density in the double-exchange (DE) theory and the magnetization σ in the current carrier density collapse (CCDC) theory. With this model, we have checked the DE and CCDC theories with our experimental results of the transport behavior. The DE theory yields agreement with the experimental resistivity excellently, in which the conductivity is the sum of the polaronic and itinerant electronic conductivity for the insulator-metal transition regime. The fitting curves of the resistivity by the CCDC theory deviate from the experiment seriously. This might be caused by the improper assumption of the temperature-dependent carrier density and the temperature-independent carrier mobility. Therefore, it is concluded that the DE theory is more suitable to explain the conductive mechanism in perovskite manganites.

  8. Thermal conductance of superlattice junctions

    SciTech Connect

    Lu, Simon; McGaughey, Alan J. H.

    2015-05-15

    We use molecular dynamics simulations and the lattice-based scattering boundary method to compute the thermal conductance of finite-length Lennard-Jones superlattice junctions confined by bulk crystalline leads. The superlattice junction thermal conductance depends on the properties of the leads. For junctions with a superlattice period of four atomic monolayers at temperatures between 5 and 20 K, those with mass-mismatched leads have a greater thermal conductance than those with mass-matched leads. We attribute this lead effect to interference between and the ballistic transport of emergent junction vibrational modes. The lead effect diminishes when the temperature is increased, when the superlattice period is increased, and when interfacial disorder is introduced, but is reversed in the harmonic limit.

  9. Ethics: problems of clinical conduct.

    PubMed

    Luglié, P F; Campus, G; Lai, V

    2005-09-01

    The study provides a framework for ethical medical conduct. A number of articles of International Law, the Italian Constitution, the Penal Code and the Medical Code of Conduct have therefore been taken into consideration. Art. 32 of the Italian Constitution, relating to the ''right to health'' is examined, paying particular attention to certain parts, and is related to Art. 35 of the European Union Charter of Fundamental Rights. In considering Art. 43 of the Penal Code, which addresses the psychological element of criminal acts, reference is made to the Medical Code of Conduct and to the Hippocratic Oath. The considerations made point up the importance of a relationship of trust and esteem between doctor and patient in clinical practice, and that this approach must be cultivated starting from the first year of university studies. PMID:16215531

  10. Low Conductivity Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming

    2005-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and requirements will be discussed. An experimental approach is established to monitor in real time the thermal conductivity of the coating systems subjected to high-heat-flux, steady-state and cyclic temperature gradients. Advanced low conductivity thermal barrier coatings have also been developed using a multi-component defect clustering approach, and shown to have improved thermal stability. The durability and erosion resistance of low conductivity thermal barrier coatings have been improved utilizing advanced coating architecture design, composition optimization, in conjunction with more sophisticated modeling and design tools.

  11. Slow Conduction in Cardiac Muscle

    PubMed Central

    Lieberman, Melvyn; Kootsey, J. Mailen; Johnson, Edward A.; Sawanobori, Tohru

    1973-01-01

    Mechanisms of slow conduction in cardiac muscle are categorized and the most likely identified. Propagating action potentials were obtained experimentally from a synthetically grown strand of cardiac muscle (around 50 μm by 30 mm) and theoretically from a one-dimensional cable model that incorporated varying axial resistance and membrane properties along its length. Action potentials propagated at about 0.3 m/s, but in some synthetic strands there were regions (approximately 100 μm in length) where the velocity decreased to 0.002 m/s. The electrophysiological behavior associated with this slow conduction was similar to that associated with slow conduction in naturally occurring cardiac muscle (notches, Wenckebach phenomena, and block). Theoretically, reasonable changes in specific membrane capacitance, membrane activity, and various changes in geometry were insufficient to account for the observed slow conduction velocities. Conduction velocities as low as 0.009 m/s, however, could be obtained by increasing the resistance (ri) of connections between the cells in the cable; velocities as low as 0.0005 m/s could be obtained by a further increase in ri made possible by a reduction in membrane activity by one-fourth, which in itself decreased conduction velocity by only a factor of 1/1.4. As a result of these findings, several of the mechanisms that have been postulated, previously, are shown to be incapable of accounting for delays such as those which occur in the synthetic strand as well as in the atrioventricular (VA) node. ImagesFIGURE 1FIGURE 2FIGURE 3FIGURE 4 PMID:4709519

  12. Conductive Channel for Energy Transmission

    NASA Astrophysics Data System (ADS)

    Apollonov, Victor V.

    2011-11-01

    For many years the attempts to create conductive channels of big length were taken in order to study the upper atmosphere and to settle special tasks, related to energy transmission. There upon the program of creation of "Impulsar" represents a great interest, as this program in a combination with high-voltage high repetition rate electrical source can be useful to solve the above mentioned problems (N. Tesla ideas for the days of high power lasers). The principle of conductive channel production can be shortly described as follows. The "Impulsar"—laser jet engine vehicle—propulsion take place under the influence of powerful high repetition rate pulse-periodic laser radiation. In the experiments the CO2—laser and solid state Nd:YAG laser systems had been used. Active impulse appears thanks to air breakdown (<30 km) or to the breakdown of ablated material on the board (>30 km), placed in the vicinity of the focusing mirror-acceptor of the breakdown waves. With each pulse of powerful laser the device rises up, leaving a bright and dense trace of products with high degree of ionization and metallization by conductive nano-particles due to ablation. Conductive dust plasma properties investigation in our experiments was produced by two very effective approaches: high power laser controlled ablation and by explosion of wire. Experimental and theoretical results of conductive canal modeling will be presented. The estimations show that with already experimentally demonstrated figures of specific thrust impulse the lower layers of the Ionosphere can be reached in several ten seconds that is enough to keep the high level of channel conductivity and stability with the help of high repetition rate high voltage generator. Some possible applications for new technology are highlighted.

  13. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C.A.; Xu, K.; Liu, C.

    1996-01-16

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100 C or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors. 4 figs.

  14. Quantized ionic conductance in nanopores.

    PubMed

    Zwolak, Michael; Lagerqvist, Johan; Di Ventra, Massimiliano

    2009-09-18

    Ionic transport in nanopores is a fundamentally and technologically important problem in view of its occurrence in biological processes and its impact on novel DNA sequencing applications. Using molecular dynamics simulations we show that ion transport may exhibit strong nonlinearities as a function of the pore radius reminiscent of the conductance quantization steps as a function of the transverse cross section of quantum point contacts. In the present case, however, conductance steps originate from the break up of the hydration layers that form around ions in aqueous solution. We discuss this phenomenon and the conditions under which it should be experimentally observable. PMID:19792463

  15. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C. Austen; Xu, Kang; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors.

  16. Conductive Composites Made Less Expensively

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    2005-01-01

    The use of electrically conductive composite structures for electrostatic dissipation, electromagnetic interference shielding, and ground return planes could save between 30 and 90 percent of the mass of the structure, in comparison to aluminum. One strategy that has been shown to make conducting composites effectively uses intercalated graphite fiber as the reinforcement. Intercalation--the insertion of guest atoms or molecules between the graphene planes--can lower the electrical resistivity of graphite fibers by as much as a factor of 10, without sacrificing mechanical or thermal properties.

  17. Conducting polyaniline nanowire electrode junction

    NASA Astrophysics Data System (ADS)

    Gaikwad, Sumedh; Bodkhe, Gajanan; Deshmukh, Megha; Patil, Harshada; Rushi, Arti; Shirsat, Mahendra D.; Koinkar, Pankaj; Kim, Yun-Hae; Mulchandani, Ashok

    2015-03-01

    In this paper, a synthesis of conducting polyaniline nanowires electrode junction (CPNEJ) has been reported. Conducting polyaniline nanowires electrode junction on Si/SiO2 substrate (having 3 μm gap between two gold microelectrodes) is prepared. Polyaniline nanowires with diameter (ca. 140 nm to 160 nm) were synthesized by one step electrochemical polymerization using galvanostatic (constant current) technique to bridge this gap. The surface morphology of CPNEJ was studied by scanning electron microscope (SEM). The synthesized CPNEJ is an excellent platform for biosensor applications.

  18. 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

  19. Conduction in Carbon Nanotube Networks

    NASA Astrophysics Data System (ADS)

    Kaiser, A. B.; Rogers, S. A.

    2003-10-01

    Recent measurements of the resistivity of single-wall carbon nanotube (SWNT) networks are consistent with our model of metallic conduction interrupted by barriers. We extend our model of thermopower nonlinearities due to peaks in the density of electronic states and apply it to recent thermopower data for carbon nanotube networks.

  20. Conductive hydrogel containing 3-ionene

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor)

    1977-01-01

    Cationic polyelectrolytes formed by the polymerization in absence of oxygen of a monomer of the general formula: dispersed ##STR1## where x is 3 or more than 6 and Z is I, Br or Cl to form high charge density linear polymers are dispered in a water-soluble polymer such as polyvinyl alcohol to form a conductive hydrogel.

  1. 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…

  2. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, Thomas E.; Spieker, David A.

    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.

  3. 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.

  4. Going public: good scientific conduct.

    PubMed

    Meyer, Gitte; Sandøe, Peter

    2012-06-01

    The paper addresses issues of scientific conduct regarding relations between science and the media, relations between scientists and journalists, and attitudes towards the public at large. In the large and increasing body of literature on scientific conduct and misconduct, these issues seem underexposed as ethical challenges. Consequently, individual scientists here tend to be left alone with problems and dilemmas, with no guidance for good conduct. Ideas are presented about how to make up for this omission. Using a practical, ethical approach, the paper attempts to identify ways scientists might deal with ethical public relations issues, guided by a norm or maxim of openness. Drawing on and rethinking the CUDOS codification of the scientific ethos, as it was worked out by Robert K. Merton in 1942, we propose that this, which is echoed in current codifications of norms for good scientific conduct, contains a tacit maxim of openness which may naturally be extended to cover the public relations of science. Discussing openness as access, accountability, transparency and receptiveness, the argumentation concentrates on the possible prevention of misconduct with respect to, on the one hand, sins of omission-withholding important information from the public-and, on the other hand, abuses of the authority of science in order to gain publicity. Statements from interviews with scientists are used to illustrate how scientists might view the relevance of the issues raised. PMID:21088921

  5. Conducting the Job Task Analysis.

    ERIC Educational Resources Information Center

    Burkhart, Jennifer

    This guide, which is intended for project directors, coordinators, and other professional staff involved in developing and delivering workplace education programs, explains the process of conducting a job task analysis to create customized curricula to meet the workplace education students' needs. After a brief discussion of the rationale for…

  6. How to Conduct Ethnographic Research

    ERIC Educational Resources Information Center

    Sangasubana, Nisaratana

    2011-01-01

    The purpose of this paper is to describe the process of conducting ethnographic research. Methodology definition and key characteristics are given. The stages of the research process are described including preparation, data gathering and recording, and analysis. Important issues such as reliability and validity are also discussed.

  7. Conducting Simulation Studies in Psychometrics

    ERIC Educational Resources Information Center

    Feinberg, Richard A.; Rubright, Jonathan D.

    2016-01-01

    Simulation studies are fundamental to psychometric discourse and play a crucial role in operational and academic research. Yet, resources for psychometricians interested in conducting simulations are scarce. This Instructional Topics in Educational Measurement Series (ITEMS) module is meant to address this deficiency by providing a comprehensive…

  8. Evolution of rapid nerve conduction.

    PubMed

    Castelfranco, Ann M; Hartline, Daniel K

    2016-06-15

    Rapid conduction of nerve impulses is a priority for organisms needing to react quickly to events in their environment. While myelin may be viewed as the crowning innovation bringing about rapid conduction, the evolution of rapid communication mechanisms, including those refined and enhanced in the evolution of myelin, has much deeper roots. In this review, a sequence is traced starting with diffusional communication, followed by transport-facilitated communication, the rise of electrical signaling modalities, the invention of voltage-gated channels and "all-or-none" impulses, the emergence of elongate nerve axons specialized for communication and their fine-tuning to enhance impulse conduction speeds. Finally within the evolution of myelin itself, several innovations have arisen and have been interactively refined for speed enhancement, including the addition and sealing of layers, their limitation by space availability, and the optimization of key parameters: channel density, lengths of exposed nodes and lengths of internodes. We finish by suggesting several design principles that appear to govern the evolution of rapid conduction. This article is part of a Special Issue entitled SI: Myelin Evolution. PMID:26879248

  9. Conduct Problem or Learning Disability?

    ERIC Educational Resources Information Center

    Wright, Loyd S.

    1974-01-01

    Forty-seven third grade boys with conduct problems were administered a battery of tests to determine how many had reading problems and central processing dysfunctions and the correlations between their reading performance and 1) central information processing abilities, 2) race, 3) social class, and 4) maternal employment. (Author/DB)

  10. Conductive Education: Benefits and Challenges

    ERIC Educational Resources Information Center

    Ratliffe, Katherine T.; Sanekane, Cindy

    2009-01-01

    Conductive education (CE) is an intensive, holistic approach to the education of people with physical disabilities that recognizes that teaching and learning are related to the emotional, cognitive, and physical aspects of individuals. Despite its popularity in the United States and throughout the world, research has not demonstrated a clear…

  11. Conductive Education: Appraising the Evidence

    ERIC Educational Resources Information Center

    Tuersley-Dixon, Louise; Frederickson, Norah

    2010-01-01

    Conductive education (CE) is widely reported as having a range of benefits. In the last two decades, it has expanded internationally. Educational psychologists may well encounter parents requesting this specialist intervention which is not normally offered within Local Authority special needs provision, for children with cerebral palsy and other…

  12. High thermal conductivity of diamond

    NASA Technical Reports Server (NTRS)

    Stephan, Patrick M.

    1993-01-01

    The objectives of this educational exercise were to demonstrate the high rate of heat flow from a synthetic diamond coupon and to compare it to a commonly used thermal conductor, such as copper. The principles of heat transfer by conduction and convection may also be demonstrated. A list of equipment and supplies and the procedure for the experiment are presented.

  13. Thin film ion conducting coating

    DOEpatents

    Goldner, Ronald B.; Haas, Terry; Wong, Kwok-Keung; Seward, George

    1989-01-01

    Durable thin film ion conducting coatings are formed on a transparent glass substrate by the controlled deposition of the mixed oxides of lithium:tantalum or lithium:niobium. The coatings provide durable ion transport sources for thin film solid state storage batteries and electrochromic energy conservation devices.

  14. Cardiac Conduction through Engineered Tissue

    PubMed Central

    Choi, Yeong-Hoon; Stamm, Christof; Hammer, Peter E.; Kwaku, Kevin F.; Marler, Jennifer J.; Friehs, Ingeborg; Jones, Mara; Rader, Christine M.; Roy, Nathalie; Eddy, Mau-Thek; Triedman, John K.; Walsh, Edward P.; McGowan, Francis X.; del Nido, Pedro J.; Cowan, Douglas B.

    2006-01-01

    In children, interruption of cardiac atrioventricular (AV) electrical conduction can result from congenital defects, surgical interventions, and maternal autoimmune diseases during pregnancy. Complete AV conduction block is typically treated by implanting an electronic pacemaker device, although long-term pacing therapy in pediatric patients has significant complications. As a first step toward developing a substitute treatment, we implanted engineered tissue constructs in rat hearts to create an alternative AV conduction pathway. We found that skeletal muscle-derived cells in the constructs exhibited sustained electrical coupling through persistent expression and function of gap junction proteins. Using fluorescence in situ hybridization and polymerase chain reaction analyses, myogenic cells in the constructs were shown to survive in the AV groove of implanted hearts for the duration of the animal’s natural life. Perfusion of hearts with fluorescently labeled lectin demonstrated that implanted tissues became vascularized and immunostaining verified the presence of proteins important in electromechanical integration of myogenic cells with surrounding recipient rat cardiomyocytes. Finally, using optical mapping and electrophysiological analyses, we provide evidence of permanent AV conduction through the implant in one-third of recipient animals. Our experiments provide a proof-of-principle that engineered tissue constructs can function as an electrical conduit and, ultimately, may offer a substitute treatment to conventional pacing therapy. PMID:16816362

  15. Thermal Conductivity of Rubble Piles

    NASA Astrophysics Data System (ADS)

    Luan, Jing; Goldreich, Peter

    2015-11-01

    Rubble piles are a common feature of solar system bodies. They are composed of monolithic elements of ice or rock bound by gravity. Voids occupy a significant fraction of the volume of a rubble pile. They can exist up to pressure P≈ {ε }Yμ , where {ε }Y is the monolithic material's yield strain and μ its rigidity. At low P, contacts between neighboring elements are confined to a small fraction of their surface areas. As a result, the effective thermal conductivity of a rubble pile, {k}{con}≈ k{(P/({ε }Yμ ))}1/2, can be orders of magnitude smaller than the thermal conductivity of its monolithic elements, k. In a fluid-free environment, only radiation can transfer energy across voids. It contributes an additional component, {k}{rad}=16{\\ell }σ {T}3/3, to the total effective conductivity, {k}{eff}={k}{con}+{k}{rad}. Here ℓ, the inverse of the opacity per unit volume, is of the order of the size of the elements, and voids. An important distinction between {k}{con} and {k}{rad} is that the former is independent of the size of the elements, whereas the latter is proportional to it. Our expression for {k}{eff} provides a good fit to the depth dependence of thermal conductivity in the top 140 cm of the lunar regolith. It also offers a good starting point for detailed modeling of thermal inertias for asteroids and satellites. Measurement of the response of surface temperature to variable insolation is a valuable diagnostic of a regolith. There is an opportunity for careful experiments under controlled laboratory conditions to test models of thermal conductivity such as the one we outline.

  16. 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

  17. High-Thermal-Conductivity Fabrics

    NASA Technical Reports Server (NTRS)

    Chibante, L. P. Felipe

    2012-01-01

    Heat management with common textiles such as nylon and spandex is hindered by the poor thermal conductivity from the skin surface to cooling surfaces. This innovation showed marked improvement in thermal conductivity of the individual fibers and tubing, as well as components assembled from them. The problem is centered on improving the heat removal of the liquid-cooled ventilation garments (LCVGs) used by astronauts. The current design uses an extensive network of water-cooling tubes that introduces bulkiness and discomfort, and increases fatigue. Range of motion and ease of movement are affected as well. The current technology is the same as developed during the Apollo program of the 1960s. Tubing material is hand-threaded through a spandex/nylon mesh layer, in a series of loops throughout the torso and limbs such that there is close, form-fitting contact with the user. Usually, there is a nylon liner layer to improve comfort. Circulating water is chilled by an external heat exchanger (sublimator). The purpose of this innovation is to produce new LCVG components with improved thermal conductivity. This was addressed using nanocomposite engineering incorporating high-thermalconductivity nanoscale fillers in the fabric and tubing components. Specifically, carbon nanotubes were added using normal processing methods such as thermoplastic melt mixing (compounding twin screw extruder) and downstream processing (fiber spinning, tubing extrusion). Fibers were produced as yarns and woven into fabric cloths. The application of isotropic nanofillers can be modeled using a modified Nielsen Model for conductive fillers in a matrix based on Einstein s viscosity model. This is a drop-in technology with no additional equipment needed. The loading is limited by the ability to maintain adequate dispersion. Undispersed materials will plug filtering screens in processing equipment. Generally, the viscosity increases were acceptable, and allowed the filled polymers to still be

  18. Dielectric properties of conductive ionomers

    NASA Astrophysics Data System (ADS)

    Klein, Robert James

    Ion and polymer dynamics of ion-containing polymers were investigated, with the majority of results obtained from application of a physical model of electrode polarization (EP) to dielectric spectroscopy data. The physical model of MacDonald, further developed by Coelho, was extended for application to tan delta (the ratio of dielectric loss to dielectric constant) as a function of frequency. The validity of this approach was confirmed by plotting the characteristic EP time as a function of thickness and comparing the actual and predicted unrelaxed dielectric constant for a poly(ethylene oxide) (PEO)-based ionomer neutralized by lithium, sodium, and cesium. Results were obtained for ion mobility and mobile ion concentration for a neat PEO-based ionomer, two (methoxyethoxy-ethoxy phosphazene) (MEEP) -based ionomers, two MEEP-based salt-doped polymers, sulfonated polystyrene (SPS) neutralized by sodium with a high sulfonation fraction, and SPS neutralized by zinc with a low sulfonation fraction. Additionally, the conductivity parameters of six plasticized forms of a neat PEO-based ionomer were characterized, but the method apparently failed to correctly evaluate bulk ionic behavior. In all cases except the SPS ionomers ion mobility follows a Vogel-Fulcher-Tammann (VFT) temperature dependence. In all cases, mobile ion concentration follows an Arrhenius temperature dependence. Fitting parameters from these two relationships yielded direct information about the state of ionic diffusion and ion pairing in each system. Combination of these two functionalities predicts a relationship for conductivity that is significantly different than the VFT relation typically used in the literature to fit conductivity. The most outstanding result was the extremely small fraction of ions found to be mobile. For ionomers it can be concluded that the primary reason for low conductivities arises from the low fraction of mobile ions. The local and segmental dynamics of the neat and

  19. Conducting Miller-Urey Experiments

    NASA Technical Reports Server (NTRS)

    Parker, Eric Thomas; Cleaves, Henderson James; Burton, Aaron S.; Glavin, Daniel P.; Dworkin, Jason; Zhou, Manshui; Bada, Jeffrey L.; Fernandez, Facundo M.

    2014-01-01

    In 1953, Stanley Miller reported the production of biomolecules from simple gaseous starting materials, using apparatus constructed to simulate the primordial Earth's atmosphere-ocean system. Miller introduced 200 ml of water, 100 mmHg of H2, 200mmHg of CH4, and 200mmHg of NH3 into the apparatus, then subjected this mixture, under reflux, to an electric discharge for a week, while the water was simultaneously heated. The purpose of this manuscript is to provide the reader with a general experimental protocol that can be used to conduct a Miller-Urey type spark discharge experiment, using a simplified 3 L reaction flask. Since the experiment involves exposing inflammable gases to a high voltage discharge, it is worth highlighting important steps that reduce the risk of explosion. The general procedures described in this work can be extrapolated to design and conduct a wide variety of electric discharge experiments simulating primitive planetary environments.

  20. Conducting Research With Community Groups.

    PubMed

    Doornbos, Mary Molewyk; Ayoola, Adejoke; Topp, Robert; Zandee, Gail Landheer

    2015-10-01

    Nurse scientists are increasingly recognizing the necessity of conducting research with community groups to effectively address complex health problems and successfully translate scientific advancements into the community. Although several barriers to conducting research with community groups exist, community-based participatory research (CBPR) has the potential to mitigate these barriers. CBPR has been employed in programs of research that respond in culturally sensitive ways to identify community needs and thereby address current health disparities. This article presents case studies that demonstrate how CBPR principles guided the development of (a) a healthy body weight program for urban, underserved African American women; (b) a reproductive health educational intervention for urban, low-income, underserved, ethnically diverse women; and (c) a pilot anxiety/depression intervention for urban, low-income, underserved, ethnically diverse women. These case studies illustrate the potential of CBPR as an orientation to research that can be employed effectively in non-research-intensive academic environments. PMID:25724557

  1. Conduction at a ferroelectric interface

    DOE PAGESBeta

    Marshall, Matthew S. J.; Malashevich, Andrei; Disa, Ankit S.; Han, Myung -Geun; Chen, Hanghui; Zhu, Yimei; Ismail-Beigi, Sohrab; Walker, Frederick J.; Ahn, Charles H.

    2014-11-05

    Typical logic elements utilizing the field effect rely on the change in carrier concentration due to the field in the channel region of the device. Ferroelectric-field-effect devices provide a nonvolatile version of this effect due to the stable polarization order parameter in the ferroelectric. In this study, we describe an oxide/oxide ferroelectric heterostructure device based on (001)-oriented PbZr₀̣.₂Ti₀.₈O₃-LaNiO₃ where the dominant change in conductivity is a result of a significant mobility change in the interfacial channel region. The effect is confined to a few atomic layers at the interface and is reversible by switching the ferroelectric polarization. More interestingly, inmore » one polarization state, the field effect induces a 1.7 eV shift of the interfacial bands to create a new conducting channel in the interfacial PbO layer of the ferroelectric.« less

  2. Weyl corrections to holographic conductivity

    SciTech Connect

    Ritz, Adam; Ward, John

    2009-03-15

    For conformal field theories which admit a dual gravitational description in anti-de Sitter space, electrical transport properties, such as conductivity and charge diffusion, are determined by the dynamics of a U(1) gauge field in the bulk and thus obey universality relations at the classical level due to the uniqueness of the Maxwell action. We analyze corrections to these transport parameters due to higher-dimension operators in the bulk action, beyond the leading Maxwell term, of which the most significant involves a coupling to the bulk Weyl tensor. We show that the ensuing corrections to conductivity and the diffusion constant break the universal relation with the U(1) central charge observed at leading order, but are nonetheless subject to interesting bounds associated with causality in the boundary conformal field theory.

  3. Conducting Research with Community Groups

    PubMed Central

    Doornbos, Mary Molewyk; Ayoola, Adejoke; Topp, Robert; Zandee, Gail Landheer

    2016-01-01

    Nurse scientists are increasingly recognizing the necessity of conducting research with community groups to effectively address complex health problems and successfully translate scientific advancements into the community. While several barriers to conducting research with community groups exist, community based participatory research (CBPR) has the potential to mitigate these barriers. CBPR has been employed in programs of research that respond in culturally sensitive ways to identify community needs and thereby address current health disparities. This manuscript presents case studies that demonstrate how CBPR principles guided the development of: (a) a healthy body weight program for urban, underserved African-American women, (b) a reproductive health educational intervention for urban, low-income, underserved, ethnically diverse women, and (c) a pilot anxiety/depression intervention for urban, low-income, underserved, ethnically diverse women. These case studies illustrate the potential of CBPR as an orientation to research that can be employed effectively in non-research intensive academic environments. PMID:25724557

  4. Pressure sensitive conductive rubber blends

    SciTech Connect

    Hassan, H.H. ); Abdel-Bary, E.M. ); El-Mansy, M.K.; Khodair, H.A. )

    1989-12-01

    Butadiene-acrylonitrile rubber (NBR) was blended with polychloroprene (CR) according to standard techniques. The blend was mixed with different concentrations of ZnO. The vulcanized sample was subjected to electrical conductivity ({sigma}) measurements while different values of static pressure were applied on the sample. It was found that samples containing 7.5 phr ZnO showed a reasonable pressure sensitive increase of {sigma}. Furthermore, the {sigma} vs pressure relationship of rubber blend mixed with different concentrations of Fast Extrusion Furnace black (FEF) was investigated. It was found that rubber vulcanizate containing 40 phr FEF resulted in a negative value of the pressure coefficient of conductivity {approx equal} {minus} 4.5 KPa{sup {minus}1}.

  5. Variable-Conductance Heat Pipes

    NASA Technical Reports Server (NTRS)

    Antoniuk, D.

    1986-01-01

    In response to need to accurately and efficiently predict performance of variable-conductance heat pipes (VCHP's) incorporated in spacecraft thermalcontrol systems, computer code VCHPDA developed to interact with thermal analyzer programs such as SINDA (Systems Improved Numerical Differencing Analyzer). Calculates length of gas-blocked region and vapor temperature in active portion. Advantages of VCHPDA over prior programs improved accuracy, unconditional stability, and increased efficiency of solution resulting from novel approach and use of state-of-the-art numerical techniques for solving VCHP mathematical model. Code valuable tool in design and evaluation of advanced thermal-control systems using variable-conductance heat pipes. Written in FORTRAN IV for use on CDC 600 computers.

  6. Conduction at a ferroelectric interface

    SciTech Connect

    Marshall, Matthew S. J.; Malashevich, Andrei; Disa, Ankit S.; Han, Myung -Geun; Chen, Hanghui; Zhu, Yimei; Ismail-Beigi, Sohrab; Walker, Frederick J.; Ahn, Charles H.

    2014-11-05

    Typical logic elements utilizing the field effect rely on the change in carrier concentration due to the field in the channel region of the device. Ferroelectric-field-effect devices provide a nonvolatile version of this effect due to the stable polarization order parameter in the ferroelectric. In this study, we describe an oxide/oxide ferroelectric heterostructure device based on (001)-oriented PbZr₀̣.₂Ti₀.₈O₃-LaNiO₃ where the dominant change in conductivity is a result of a significant mobility change in the interfacial channel region. The effect is confined to a few atomic layers at the interface and is reversible by switching the ferroelectric polarization. More interestingly, in one polarization state, the field effect induces a 1.7 eV shift of the interfacial bands to create a new conducting channel in the interfacial PbO layer of the ferroelectric.

  7. Quantum mechanics and heat conduction

    SciTech Connect

    Bajpai, S.D. ); Mishra, S. )

    1991-08-01

    One of the fundamental problems in quantum mechanics is to find a solution of Schroedinger equation for different forms of potentials. The object of this paper is to obtain a series solution of a particular one-dimensional, time-dependent Schroedinger equation involving Hermite polynomials. The authors also show a relationship of their particular one-dimensional, time-dependent Schroedinger equation with an equation of heat conduction.

  8. 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.

  9. 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.

  10. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, Jack J.; Elling, David; Reams, Walter

    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.

  11. Conduct of operations implementation plan

    SciTech Connect

    Anderson, C.K.; Hall, R.L.

    1991-02-20

    This implementation plan describes the process and provides information and schedules that are necessary to implement and comply with the Department of Energy (DOE) Order 5480.19, {open_quotes}Conduct of Operations{close_quotes} (CoOp). This plan applies to all Pinellas Plant operations and personnel. Generally, this Plan discusses how DOE Order 5480.19 will be implemented at the Pinellas Plant.

  12. Hydraulic Conductivity Measurements Barrow 2014

    DOE Data Explorer

    Katie McKnight; Tim Kneafsey; Craig Ulrich; Jil Geller

    2015-02-22

    Six individual ice cores were collected from Barrow Environmental Observatory in Barrow, Alaska, in May of 2013 as part of the Next Generation Ecosystem Experiment (NGEE). Each core was drilled from a different location at varying depths. A few days after drilling, the cores were stored in coolers packed with dry ice and flown to Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA. 3-dimensional images of the cores were constructed using a medical X-ray computed tomography (CT) scanner at 120kV. Hydraulic conductivity samples were extracted from these cores at LBNL Richmond Field Station in Richmond, CA, in February 2014 by cutting 5 to 8 inch segments using a chop saw. Samples were packed individually and stored at freezing temperatures to minimize any changes in structure or loss of ice content prior to analysis. Hydraulic conductivity was determined through falling head tests using a permeameter [ELE International, Model #: K-770B]. After approximately 12 hours of thaw, initial falling head tests were performed. Two to four measurements were collected on each sample and collection stopped when the applied head load exceeded 25% change from the original load. Analyses were performed between 2 to 3 times for each sample. The final hydraulic conductivity calculations were computed using methodology of Das et al., 1985.

  13. Proton-conducting cerate ceramics

    SciTech Connect

    Pederson, L.R.; Coffey, G.W.; Bates, J.L.; Weber, W.J.

    1996-08-01

    Single-cell solid oxide fuel cells were constructed using strontium cerate as the electrolyte and their performance tested. Like certain zirconates, hafnates, and tantalates, the cerate perovskites are among a class of solid electrolytes that conduct protons at elevated temperatures. Depending on the temperature and chemical environment, these ceramics also support electronic and oxygen ion currents. A maximum power output of {approx}100 mW per cm{sup 2} electrolyte surface area was obtained at 900{degrees}C using 4% hydrogen as the fuel and air as the oxidant. A series of rare earth/ceria/zirconia were prepared and their electrical properties characterized. Rare earth dopants included ytterbia, yttria, terbia, and europia. Ionic conductivities were highest for rare earth/ceria and rare earth zirconia compositions; a minimum in ionic conductivity for all series were found for equimolar mixtures of ceria and zirconia. Cerium oxysulfide is of interest in fossil energy applications because of its high chemical stability and refractory nature. An alternative synthesis route to preparing cerium oxysulfide powders has been developed using combustion techniques.

  14. Conductivity Anomalies in Central Europe

    NASA Astrophysics Data System (ADS)

    Neska, Anne

    2016-01-01

    This paper is a review of studies which, by applying the magnetotelluric, geomagnetic deep sounding, and magnetovariational sounding methods (the latter refers to usage of the horizontal magnetic tensor), investigate Central Europe for zones of enhanced electrical conductivity. The study areas comprise the region of the Trans-European Suture Zone (i.e. the south Baltic region and Poland), the North German Basin, the German and Czech Variscides, the Pannonian Basin (Hungary), and the Polish, Slovakian, Ukrainian, and Romanian Carpathians. This part of the world is well investigated in terms of data coverage and of the density of published studies, whereas the certainty that the results lead to comprehensive interpretations varies within the reviewed literature. A comparison of spatially coincident or adjacent studies reveals the important role that the data coverage of a distinct conductivity anomaly plays for the consistency of results. The encountered conductivity anomalies are understood as linked to basin sediments, asthenospheric upwelling, large differences in lithospheric age, and—this concerns most of them, which all concentrate in the middle crust—tectonic boundaries that developed during all mountain building phases that have taken place on the continent.

  15. One-Dimensional Heat Conduction

    SciTech Connect

    Sutton, Steven B.

    1992-03-09

    ICARUS-LLNL was developed to solve one-dimensional planar, cylindrical, or spherical conduction heat transfer problems. The IBM PC version is a family of programs including ICARUSB, an interactive BASIC heat conduction program; ICARUSF, a FORTRAN heat conduction program; PREICAR, a BASIC preprocessor for ICARUSF; and PLOTIC and CPLOTIC, interpretive BASIC and compiler BASIC plot postprocessor programs. Both ICARUSB and ICARUSF account for multiple material regions and complex boundary conditions, such as convection or radiation. In addition, ICARUSF accounts for temperature-dependent material properties and time or temperature-dependent boundary conditions. PREICAR is a user-friendly preprocessor used to generate or modify ICARUSF input data. PLOTIC and CPLOTIC generate plots of the temperature or heat flux profile at specified times, plots of the variation of temperature or heat flux with time at selected nodes, or plots of the solution grid. First developed in 1974 to allow easy modeling of complex one-dimensional systems, its original application was in the nuclear explosive testing program. Since then it has undergone extensive revision and been applied to problems dealing with laser fusion target fabrication, heat loads on underground tests, magnetic fusion switching tube anodes, and nuclear waste isolation canisters.

  16. Aeromonas hydrophila produces conductive nanowires.

    PubMed

    Castro, Laura; Vera, Mario; Muñoz, Jesús Ángel; Blázquez, María Luisa; González, Felisa; Sand, Wolfgang; Ballester, Antonio

    2014-11-01

    Aeromonas hydrophila is a facultative anaerobe which, under conditions of oxygen depletion, uses Fe(III) as electron acceptor. A. hydrophila produces pili during growth with Fe(III). The study was focused on the characterization of the morphology, the electrical properties and the nature of the bacterial pili. Scanning electron microscopy and conductive-probe atomic force microscopy revealed the presence of filaments between cells and substrate and their conductive nature. Our results indicate that pili of A. hydrophila strain A might serve as biological nanowires, transferring electrons from the cell surface to the surface of Fe(III) oxides and, in addition, the possibility of playing a role in inter/intra species signaling. Quorum sensing (QS) is recognized as one of the main regulatory ways for extracellular polymeric substances (EPS) production and biofilm formation. We present evidence that nanowire formation can be regulated by addition of synthetic acyl-homoserine lactones (AHL). These conductive pili may be involved in various interactions, and their protein components might be usable in the future for biotechnological approaches in materials science. PMID:25283724

  17. One-Dimensional Heat Conduction

    Energy Science and Technology Software Center (ESTSC)

    1992-03-09

    ICARUS-LLNL was developed to solve one-dimensional planar, cylindrical, or spherical conduction heat transfer problems. The IBM PC version is a family of programs including ICARUSB, an interactive BASIC heat conduction program; ICARUSF, a FORTRAN heat conduction program; PREICAR, a BASIC preprocessor for ICARUSF; and PLOTIC and CPLOTIC, interpretive BASIC and compiler BASIC plot postprocessor programs. Both ICARUSB and ICARUSF account for multiple material regions and complex boundary conditions, such as convection or radiation. In addition,more » ICARUSF accounts for temperature-dependent material properties and time or temperature-dependent boundary conditions. PREICAR is a user-friendly preprocessor used to generate or modify ICARUSF input data. PLOTIC and CPLOTIC generate plots of the temperature or heat flux profile at specified times, plots of the variation of temperature or heat flux with time at selected nodes, or plots of the solution grid. First developed in 1974 to allow easy modeling of complex one-dimensional systems, its original application was in the nuclear explosive testing program. Since then it has undergone extensive revision and been applied to problems dealing with laser fusion target fabrication, heat loads on underground tests, magnetic fusion switching tube anodes, and nuclear waste isolation canisters.« less

  18. Nerve conduction and electromyography studies.

    PubMed

    Kane, N M; Oware, A

    2012-07-01

    Nerve conduction studies (NCS) and electromyography (EMG), often shortened to 'EMGs', are a useful adjunct to clinical examination of the peripheral nervous system and striated skeletal muscle. NCS provide an efficient and rapid method of quantifying nerve conduction velocity (CV) and the amplitude of both sensory nerve action potentials (SNAPs) and compound motor action potentials (cMAPs). The CV reflects speed of propagation of action potentials, by saltatory conduction, along large myelinated axons in a peripheral nerve. The amplitude of SNAPs is in part determined by the number of axons in a sensory nerve, whilst amplitude of cMAPs reflects integrated function of the motor axons, neuromuscular junction and striated muscle. Repetitive nerve stimulation (RNS) can identify defects of neuromuscular junction (NMJ) transmission, pre- or post-synaptic. Needle EMG examination can detect myopathic changes in muscle and signs of denervation. Combinations of these procedures can establish if motor and/or sensory nerve cell bodies or peripheral nerves are damaged (e.g. motor neuronopathy, sensory ganglionopathy or neuropathy), and also indicate if the primary target is the axon or the myelin sheath (i.e. axonal or demyelinating neuropathies). The distribution of nerve damage can be determined as either generalised, multifocal (mononeuropathy multiplex) or focal. The latter often due to compression at the common entrapment sites (such as the carpal tunnel, Guyon's canal, cubital tunnel, radial groove, fibular head and tarsal tunnel, to name but a few of the reported hundred or so 'entrapment neuropathies'). PMID:22614870

  19. Hydraulic conductivity of rock fractures

    SciTech Connect

    Zimmerman, R.W.; Bodvarsson, G.S.

    1994-10-01

    Yucca Mountain, Nevada contains numerous geological units that are highly fractured. A clear understanding of the hydraulic conductivity of fractures has been identified as an important scientific problem that must be addressed during the site characterization process. The problem of the flow of a single-phase fluid through a rough-walled rock fracture is discussed within the context of rigorous fluid mechanics. The derivation of the cubic law is given as the solution to the Navier-Stokes equations for flow between smooth, parallel plates, the only fracture geometry that is amenable to exact treatment. The various geometric and kinetic conditions that are necessary in order for the Navier-Stokes equations to be replaced by the more tractable lubrication or Hele-Shaw equations are studied and quantified. Various analytical and numerical results are reviewed pertaining to the problem of relating the effective hydraulic aperture to the statistics of the aperture distribution. These studies all lead to the conclusion that the effective hydraulic aperture is always less than the mean aperture, by a factor that depends on the ratio of the mean value of the aperture to its standard deviation. The tortuosity effect caused by regions where the rock walls are in contact with each other is studied using the Hele-Shaw equations, leading to a simple correction factor that depends on the area fraction occupied by the contact regions. Finally, the predicted hydraulic apertures are compared to measured values for eight data sets from the literature for which aperture and conductivity data were available on the same fracture. It is found that reasonably accurate predictions of hydraulic conductivity can be made based solely on the first two moments of the aperture distribution function, and the proportion of contact area. 68 refs.

  20. THERMAL CONDUCTIVITY ANALYSIS OF GASES

    DOEpatents

    Clark, W.J.

    1949-06-01

    This patent describes apparatus for the quantitative analysis of a gaseous mixture at subatmospheric pressure by measurement of its thermal conductivity. A heated wire forms one leg of a bridge circuit, while the gas under test is passed about the wire at a constant rate. The bridge unbalance will be a measure of the change in composition of the gas, if compensation is made for the effect due to gas pressure change. The apparatus provides a voltage varying with fluctuations of pressure in series with the indicating device placed across the bridge, to counterbalance the voltage change caused by fluctuations in the pressure of the gaseous mixture.

  1. Bioconversion study conducted by JPL

    NASA Technical Reports Server (NTRS)

    Kalvinskas, J.

    1978-01-01

    The Jet Propulsion Laboratory (JPL) of Caltech conducted a study of bioconversion as a means of identifying the role of biomass for meeting the national energy fuel and chemical requirements and the role and means for JPL-Caltech involvement in bioconversion. The bioconversion study included the following categories; biomass sources, chemicals from biomass, thermochemical conversion of biomass to fuels, biological conversion of biomass to fuels and chemicals, and basic bioconversion sciences. A detailed review is included of the bioconversion fields cited with specific conclusions and recommendations given for future research and development and overall biomass system engineering and economic studies.

  2. NOAA's hydrolab conducts reef studies

    NASA Astrophysics Data System (ADS)

    This summer, scuba-diving scientists operating from Hydrolab, NOAA's undersea laboratory, are carrying out four experiments aimed at producing better management of coral reefs and their fishery resources. Hydrolab is located at a depth of 50 feet, near the mouth of the Salt River, off St. Croix, U.S. Virgin Islands. The lab houses four scientists for up to 2 weeks at a time, permitting them to swim out into the water to conduct research. The projects make use of both the natural coral reef near Hydrolab and the nearby artificial reef constructed for comparison studies.

  3. On Vasyliunas's equivalent conductivity formalism

    NASA Technical Reports Server (NTRS)

    Pontius, D. H., Jr.

    1992-01-01

    The Vasyliunas's (1972) equivalent conductivity formalism (ECF) for representing the coupling of the ionosphere and the magnetosphere is discussed, and a new, simpler, derivation is presented of the ECF, in which certain of the underlying assumptions and their implications are made transparent. The derivation presented indicates that the only role of the ions in the ECF is to insure quasi-neutrality. It is shown that the ECF is not as robust as usually assumed and that caution must be used to insure that reasonable results are obtained.

  4. Conducting polymer based electrochemical biosensors.

    PubMed

    Aydemir, Nihan; Malmström, Jenny; Travas-Sejdic, Jadranka

    2016-03-28

    Conducting polymer (CP)-based electrochemical biosensors have gained great attention as such biosensor platforms are easy and cost-effective to fabricate, and provide a direct electrical readout for the presence of biological analytes with high sensitivity and selectivity. CP materials themselves are both sensing elements and transducers of the biological recognition event at the same time, simplifying sensor designs. This review summarizes the advances in electrochemical biosensors based on CPs. Recognition probe immobilisation techniques, transduction mechanisms and detection of various target biomolecules have been discussed in detail. Efforts to miniaturize CP-based electrochemical biosensors and fabrication of sensor arrays are also briefly reviewed. PMID:26948182

  5. Conduction-limited crystallite melting

    NASA Astrophysics Data System (ADS)

    Lupulescu, A.; Glicksman, M. E.; Koss, M. B.

    2005-04-01

    High-purity pivalic acid (PVA) dendrites were observed growing under convection-free conditions during the isothermal dendritic growth experiment (IDGE) flown on NASA's space shuttle Columbia on STS-87. The IDGE was part of the complement of primary scientific experiments designated as the United States Microgravity Payload Mission (USMP4) launched late in 1997. The IDGE video data show that PVA dendrites may be melted without exhibiting any detectable relative motion with respect to the surrounding quiescent melt phase. Thus, melting occurs by heat conduction alone. When a small fixed superheating is imposed on pre-existing dendritic fragments, they melt steadily toward extinction. Individual fragments steadily decrease in size according to a square-root of time dependence predicted using quasi-static conduction-limited theory. Agreement between analytic melting theory and microgravity experiments was found originally if the melting process occurs under the restriction of shape-preserving conditions, where needle-like crystal fragments may be approximated as ellipsoids with a constant axial ratio. Among the new results reported here is the influence of capillarity effects on melting in needle-like crystallites, observed as a dramatic change in their axial ratio, when the size scale of a crystallite decreases below a critical value. In microgravity melting experiments, the axial ratio of individual crystallites does not remain constant, because of interactions with neighboring fragments within the mushy zone. The kinetic data were then "sectorized" to divide the total melting process into a series of short intervals. Each melting sector for a crystallite could then be approximated by a constant average value of the axial ratio. Sectorization also allows accurate prediction of melting kinetics by applying quasi-static heat conduction theory, despite the suspected presence of capillarity and the occurrence of fragmentation. These additional processes that accompany

  6. Conduction-coupled Tesla transformer

    NASA Astrophysics Data System (ADS)

    Reed, J. L.

    2015-03-01

    A proof-of-principle Tesla transformer circuit is introduced. The new transformer exhibits the high voltage-high power output signal of shock-excited transformers. The circuit, with specification of proper circuit element values, is capable of obtaining extreme oscillatory voltages. The primary and secondary portions of the circuit communicate solely by conduction. The destructive arcing between the primary and secondary inductors in electromagnetically coupled transformers is ubiquitous. Flashover is eliminated in the new transformer as the high-voltage inductors do not interpenetrate and so do not possess an annular volume of electric field. The inductors are remote from one another. The high voltage secondary inductor is isolated in space, except for a base feed conductor, and obtains earth by its self-capacitance to the surroundings. Governing equations, for the ideal case of no damping, are developed from first principles. Experimental, theoretical, and circuit simulator data are presented for the new transformer. Commercial high-temperature superconductors are discussed as a means to eliminate the counter-intuitive damping due to small primary inductances in both the electromagnetic-coupled and new conduction-coupled transformers.

  7. Optical conductivity of nodal metals

    NASA Astrophysics Data System (ADS)

    Homes, C. C.; Gu, G. D.; Tu, J. J.; Li, J.; Akrap, A.

    2014-03-01

    Fermi liquid theory is remarkably successful in describing the transport and optical properties of metals; at frequencies higher than the scattering rate, the optical conductivity adopts the well-known power law behavior σ1(ω) ~ω-2 . We have observed an unusual non-Fermi liquid response σ1(ω) ~ω - 1 +/- 0 . 2 in the ground states of several quasi two-dimensional cuprate (optimally doped Bi2Sr2CaCu2O8+δ, optimally and underdoped YBa2Cu3O7-δ) and iron-based materials (AFe2As2, A = Ba, Ca) which undergo electronic or magnetic phase transitions resulting in dramatically reduced or nodal Fermi surfaces. The identification of an inverse (or fractional) power-law behavior in the residual optical conductivity now permits the removal of this contribution, revealing the direct transitions across the gap and allowing the nature of the electron-boson coupling to be probed. The non-Fermi liquid behavior in these systems may be the result of a common Fermi surface topology of Dirac cone-like features in the electronic dispersion. Supported by the DOE under Contract No. DE-AC02-98CH10886.

  8. Radiative magnetized thermal conduction fronts

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-01-01

    The evolution of plane-parallel magnetized thermal conduction fronts in the interstellar medium (ISM) was studied. Separating the coronal ISM phase and interstellar clouds, these fronts have been thought to be the site of the intermediate-temperature regions whose presence was inferred from O VI absorption-line studies. The front evolution was followed numerically, starting from the initial discontinuous temperature distribution between the hot and cold medium, and ending in the final cooling stage of the hot medium. It was found that, for the typical ISM pressure of 4000 K/cu cm and the hot medium temperature of 10 to the 6th K, the transition from evaporation to condensation in a nonmagnetized front occurs when the front thickness is 15 pc. This thickness is a factor of 5 smaller than previously estimated. The O VI column densities in both evaporative and condensation stages agree with observations if the initial hot medium temperature Th exceeds 750,000 K. Condensing conduction fronts give better agreement with observed O VI line profiles because of lower gas temperatures.

  9. Conduction-coupled Tesla transformer.

    PubMed

    Reed, J L

    2015-03-01

    A proof-of-principle Tesla transformer circuit is introduced. The new transformer exhibits the high voltage-high power output signal of shock-excited transformers. The circuit, with specification of proper circuit element values, is capable of obtaining extreme oscillatory voltages. The primary and secondary portions of the circuit communicate solely by conduction. The destructive arcing between the primary and secondary inductors in electromagnetically coupled transformers is ubiquitous. Flashover is eliminated in the new transformer as the high-voltage inductors do not interpenetrate and so do not possess an annular volume of electric field. The inductors are remote from one another. The high voltage secondary inductor is isolated in space, except for a base feed conductor, and obtains earth by its self-capacitance to the surroundings. Governing equations, for the ideal case of no damping, are developed from first principles. Experimental, theoretical, and circuit simulator data are presented for the new transformer. Commercial high-temperature superconductors are discussed as a means to eliminate the counter-intuitive damping due to small primary inductances in both the electromagnetic-coupled and new conduction-coupled transformers. PMID:25832281

  10. Conducting Miller-Urey Experiments

    PubMed Central

    Parker, Eric T.; Cleaves, James H.; Burton, Aaron S.; Glavin, Daniel P.; Dworkin, Jason P.; Zhou, Manshui; Bada, Jeffrey L.; Fernández, Facundo M.

    2014-01-01

    In 1953, Stanley Miller reported the production of biomolecules from simple gaseous starting materials, using an apparatus constructed to simulate the primordial Earth's atmosphere-ocean system. Miller introduced 200 ml of water, 100 mmHg of H2, 200 mmHg of CH4, and 200 mmHg of NH3 into the apparatus, then subjected this mixture, under reflux, to an electric discharge for a week, while the water was simultaneously heated. The purpose of this manuscript is to provide the reader with a general experimental protocol that can be used to conduct a Miller-Urey type spark discharge experiment, using a simplified 3 L reaction flask. Since the experiment involves exposing inflammable gases to a high voltage electric discharge, it is worth highlighting important steps that reduce the risk of explosion. The general procedures described in this work can be extrapolated to design and conduct a wide variety of electric discharge experiments simulating primitive planetary environments. PMID:24473135

  11. Conducting miller-urey experiments.

    PubMed

    Parker, Eric T; Cleaves, James H; Burton, Aaron S; Glavin, Daniel P; Dworkin, Jason P; Zhou, Manshui; Bada, Jeffrey L; Fernández, Facundo M

    2014-01-01

    In 1953, Stanley Miller reported the production of biomolecules from simple gaseous starting materials, using an apparatus constructed to simulate the primordial Earth's atmosphere-ocean system. Miller introduced 200 ml of water, 100 mmHg of H2, 200 mmHg of CH4, and 200 mmHg of NH3 into the apparatus, then subjected this mixture, under reflux, to an electric discharge for a week, while the water was simultaneously heated. The purpose of this manuscript is to provide the reader with a general experimental protocol that can be used to conduct a Miller-Urey type spark discharge experiment, using a simplified 3 L reaction flask. Since the experiment involves exposing inflammable gases to a high voltage electric discharge, it is worth highlighting important steps that reduce the risk of explosion. The general procedures described in this work can be extrapolated to design and conduct a wide variety of electric discharge experiments simulating primitive planetary environments. PMID:24473135

  12. Water-soluble conductive polymers

    SciTech Connect

    Aldissi, M.

    1990-05-29

    This patent describes polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

  13. Water-soluble conductive polymers

    DOEpatents

    Aldissi, M.

    1988-02-12

    Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

  14. Water-soluble conductive polymers

    DOEpatents

    Aldissi, Mahmoud

    1989-01-01

    Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

  15. Water-soluble conductive polymers

    DOEpatents

    Aldissi, Mahmoud

    1990-01-01

    Polymers which are soluble in water and are electrically conductive. The monomer repeat unit is a thiophene or pyrrole molecule having an alkyl group substituted for the hydrogen atom located in the beta position of the thiophene or pyrrole ring and having a surfactant molecule at the end of the alkyl chain. Polymers of this class having 8 or more carbon atoms in the alkyl chain exhibit liquid crystalline behavior, resulting in high electrical anisotropy. The monomer-to-monomer bonds are located between the carbon atoms which are adjacent to the sulfur or nitrogen atoms. The number of carbon atoms in the alkyl group may vary from 1 to 20 carbon atoms. The surfactant molecule consists of a sulfonate group, or a sulfate group, or a carboxylate group, and hydrogen or an alkali metal. Negative ions from a supporting electrolyte which may be used in the electrochemical synthesis of a polymer may be incorporated into the polymer during the synthesis and serve as a dopant to increase the conductivity.

  16. Advances in inherently conducting polymers

    SciTech Connect

    Aldissi, M.

    1987-09-01

    The discovery of polyacetylene as the prototype material led to extensive research on its synythesis and characterization. The techniques that emerged as the most important and promising ones are those that dealt with molecular orientation and that resulted in conductivities almost as high as that of copper. The study of dozens of other materials followed. Interest in conducting polymers stems from their nonclassical optical and electronic properties as well as their potential technological applications. However, some of the factors currently limiting their use are the lack of long-term stability and the need to develop conventional low-cost techniques for easy processing. Therefore, research was extended toward solving these problems, and progress has been recently made in that direction. The synthesis of new materials such as stable and easily processable alkylthiophenes, water-soluble polymers, and multicomponent systems, including copolymers and composites, constitutes an important step forward in the area of synthetic metals. However, a full understanding of materials chemistry and properties requires more work in the years to come. Although, few small-scale applications have proven to be successful, long-term stability and applicability tests are needed before their commercial use becomes reality.

  17. Counterion condensation and ionic conductivity

    NASA Astrophysics Data System (ADS)

    Penafiel, L. Miguel; Litovitz, Theodore A.

    1992-02-01

    The occurrence of counterion condensation is demonstrated through measurements of the incremental ionic conductivity of pH buffered Na polyacrylate solutions. pH values were selected to allow variation of the charge density parameter ξ in the range between 0.4 and 2.8, that is, across ξ=1, the theoretical critical level for counterion condensation. The results show two regions where the incremental conductivity, ΔσP, varies differently with ξ. For ξ<1.3, ΔσP remains relatively constant. A sharp drop in ΔσP is observed between ξ=1.3 and ξ=1.7 corresponding to the onset of counterion condensation. It is suggested that this discontinuity reflects a drastic change in the polyion mobility caused by a structural rearrangement of the macromolecule. For ξ≳1.7, ΔσP decreases with approximately constant slope. This latter behavior agrees qualitatively but not quantitatively with the prediction of the counterion condensation model.

  18. Optical conductivity of nodal metals

    PubMed Central

    Homes, C. C.; Tu, J. J.; Li, J.; Gu, G. D.; Akrap, A.

    2013-01-01

    Fermi liquid theory is remarkably successful in describing the transport and optical properties of metals; at frequencies higher than the scattering rate, the optical conductivity adopts the well-known power law behavior σ1(ω) ∝ ω−2. We have observed an unusual non-Fermi liquid response σ1(ω) ∝ ω−1±0.2 in the ground states of several cuprate and iron-based materials which undergo electronic or magnetic phase transitions resulting in dramatically reduced or nodal Fermi surfaces. The identification of an inverse (or fractional) power-law behavior in the residual optical conductivity now permits the removal of this contribution, revealing the direct transitions across the gap and allowing the nature of the electron-boson coupling to be probed. The non-Fermi liquid behavior in these systems may be the result of a common Fermi surface topology of Dirac cone-like features in the electronic dispersion. PMID:24336241

  19. Efficient Reformulation of HOTFGM: Heat Conduction with Variable Thermal Conductivity

    NASA Technical Reports Server (NTRS)

    Zhong, Yi; Pindera, Marek-Jerzy; Arnold, Steven M. (Technical Monitor)

    2002-01-01

    Functionally graded materials (FGMs) have become one of the major research topics in the mechanics of materials community during the past fifteen years. FGMs are heterogeneous materials, characterized by spatially variable microstructure, and thus spatially variable macroscopic properties, introduced to enhance material or structural performance. The spatially variable material properties make FGMs challenging to analyze. The review of the various techniques employed to analyze the thermodynamical response of FGMs reveals two distinct and fundamentally different computational strategies, called uncoupled macromechanical and coupled micromechanical approaches by some investigators. The uncoupled macromechanical approaches ignore the effect of microstructural gradation by employing specific spatial variations of material properties, which are either assumed or obtained by local homogenization, thereby resulting in erroneous results under certain circumstances. In contrast, the coupled approaches explicitly account for the micro-macrostructural interaction, albeit at a significantly higher computational cost. The higher-order theory for functionally graded materials (HOTFGM) developed by Aboudi et al. is representative of the coupled approach. However, despite its demonstrated utility in applications where micro-macrostructural coupling effects are important, the theory's full potential is yet to be realized because the original formulation of HOTFGM is computationally intensive. This, in turn, limits the size of problems that can be solved due to the large number of equations required to mimic realistic material microstructures. Therefore, a basis for an efficient reformulation of HOTFGM, referred to as user-friendly formulation, is developed herein, and subsequently employed in the construction of the efficient reformulation using the local/global conductivity matrix approach. In order to extend HOTFGM's range of applicability, spatially variable thermal

  20. Electrostatic Spraying With Conductive Liquids

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; Dawn, Frederic S.; Erlandson, Robert E.; Atkins, Loren E.

    1989-01-01

    Thin, uniform polymer coatings applied in water base normally impossible to charge. Electrostatic sprayer modified so applies coatings suspended or dissolved in electrically conductive liquids. Nozzle and gun constructed of nonconductive molded plastic. Liquid passageway made long enough electrical leakage through it low. Coaxial hose for liquid built of polytetrafluoroethylene tube, insulating sleeve, and polyurethane jacket. Sprayer provided with insulated seal at gun-to-hose connection, nonconductive airhose, pressure tank electrically isolated from ground, and special nozzle electrode. Supply of atomizing air reduced so particle momentum controlled by electrostatic field more effectively. Developed to apply water-base polyurethane coating to woven, shaped polyester fabric. Coating provides pressure seal for fabric, which is part of spacesuit. Also useful for applying waterproof, decorative, or protective coatings to fabrics for use on Earth.

  1. Conduction heating of hydrocarbonaceous formations

    SciTech Connect

    Bridges, J. E.

    1985-10-08

    A waveguide structure is emplanted in the earth to bound a particular volume of an earth formation with a waveguide structure formed of respective rows of discrete elongated electrodes wherein the spacing between rows is greater than the distance between electrodes in a respective row and in the case of vertical electrodes substantially less than the thickness of the hydrocarbonaceous earth formation. Electrical power at no more than a relatively low frequency is applied between respective rows of the electrodes to deliver power to the formation while producing relatively uniform heating thereof and limiting the relative loss of heat to adjacent barren regions to less than a tolerable amount. At the same time the temperature of the electrodes is controlled near the vaporization point of water thereat to maintain an electrically conductive path between the electrodes and the formation.

  2. Conductive spacecraft materials development program

    NASA Technical Reports Server (NTRS)

    Lehn, W. L.

    1977-01-01

    The objectives of this program are to provide design criteria, techniques, materials, and test methods to ensure control of absolute and differential charging of spacecraft surfaces. The control of absolute and differential charging of spacecraft cannot be effected without the development of new and improved or modified materials or techniques that will provide electrical continuity over the surface of the spacecraft. The materials' photoemission, secondary emission, thermooptical, physical, and electrical properties in the space vacuum environment both in the presence and absence of electrical stress and ultraviolet, electron, and particulate radiation, are important to the achievement of charge control. The materials must be stable or have predictable response to exposure to the space environment for long periods of time. The materials of interest include conductive polymers, paints, transparent films and coatings as well as fabric coating interweaves.

  3. Electrolytic decontamination of conductive materials

    SciTech Connect

    Nelson, T.O.; Campbell, G.M.; Parker, J.L.; Getty, R.H.; Hergert, T.R.; Lindahl, K.A.; Peppers, L.G.

    1993-10-01

    Using the electrolytic method, the authors have demonstrated removal of Pu from contaminated conductive material. At EG&G Rocky Flats, they electrolytically decontaminated stainless steel. Results from this work show removal of fixed contamination, including the following geometries: planar, large radius, bolt holes, glove ports, and protruding studs. More specifically, fixed contamination was reduced from levels ranging > 1,000,000 counts per minute (cpm) down to levels ranging from 1,500 to < 250 cpm with the electrolytic method. More recently, the electrolytic work has continued at LANL as a joint project with EG&G. Impressively, electrolytic decontamination experiments on removal of Pu from oralloy coupons have shown decreases in swipable contamination that initially ranged from 500,000 to 1,500,000 disintegrations per minute (dpm) down to 0--2 dpm.

  4. The proper conduct of research.

    PubMed

    Maurer, John J

    2007-03-01

    Scientific misconduct has garnered recent attention by the media over scandals concerning falsification and fabrication of data surrounding potentially promising breakthroughs in stem-cell research, allegations of plagiarism at a U.S. university, and financial conflicts of interest between researchers and drug companies. While this makes for interesting copy, discussion of scientific fraud provides an excellent opportunity to review ethical standards for research and examine the conflicts that confront researchers today. This review specifically focuses on five areas that involve scientific integrity-plagiarism, falsification, fabrication, authorship, and conflict of interest-as well as nuances in each area that even senior investigators may not be aware of (e.g., self-plagiarism). The standards for ethical conductance of research discussed in this review are those set by many scientific, peer-reviewed journals and by federal and private granting agencies, and therefore it highlights the expectations and guidelines surrounding manuscript and grant submissions and review, and the consequences associated with violations. This review is intended to stimulate discussion among readers and assess what is necessary to become a good, competitive, but ethical researcher, especially in an era of shrinking financial resources for research. PMID:17461259

  5. Heat conduction of symmetric lattices

    NASA Astrophysics Data System (ADS)

    Nie, Linru; Yu, Lilong; Zheng, Zhigang; Shu, Changzheng

    2013-06-01

    Heat conduction of symmetric Frenkel-Kontorova (FK) lattices with a coupling displacement was investigated. Through simplifying the model, we derived analytical expression of thermal current of the system in the overdamped case. By means of numerical calculations, the results indicate that: (i) As the coupling displacement d equals to zero, temperature oscillations of the heat baths linked with the lattices can control magnitude and direction of the thermal current; (ii) Whether there is a temperature bias or not, the thermal current oscillates periodically with d, whose amplitudes become greater and greater; (iii) As d is not equal to zero, the thermal current monotonically both increases and decreases with temperature oscillation amplitude of the heat baths, dependent on values of d; (iv) The coupling displacement also induces nonmonotonic behaviors of the thermal current vs spring constant of the lattice and coupling strength of the lattices; (v) These dynamical behaviors come from interaction of the coupling displacement with periodic potential of the FK lattices. Our results have the implication that the coupling displacement plays a crucial role in the control of heat current.

  6. Rigidity-tuning conductive elastomer

    NASA Astrophysics Data System (ADS)

    Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel

    2015-06-01

    We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE-PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ˜6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE-PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE-PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation.

  7. Cystic Fibrosis Transmembrane Conductance Regulator

    PubMed Central

    Smith, Stephen S.; Steinle, Erich D.; Meyerhoff, Mark E.; Dawson, David C.

    1999-01-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) Cl channel exhibits lyotropic anion selectivity. Anions that are more readily dehydrated than Cl exhibit permeability ratios (PS/PCl) greater than unity and also bind more tightly in the channel. We compared the selectivity of CFTR to that of a synthetic anion-selective membrane [poly(vinyl chloride)–tridodecylmethylammonium chloride; PVC-TDMAC] for which the nature of the physical process that governs the anion-selective response is more readily apparent. The permeability and binding selectivity patterns of CFTR differed only by a multiplicative constant from that of the PVC-TDMAC membrane; and a continuum electrostatic model suggested that both patterns could be understood in terms of the differences in the relative stabilization of anions by water and the polarizable interior of the channel or synthetic membrane. The calculated energies of anion–channel interaction, derived from measurements of either permeability or binding, varied as a linear function of inverse ionic radius (1/r), as expected from a Born-type model of ion charging in a medium characterized by an effective dielectric constant of 19. The model predicts that large anions, like SCN, although they experience weaker interactions (relative to Cl) with water and also with the channel, are more permeant than Cl because anion–water energy is a steeper function of 1/r than is the anion–channel energy. These large anions also bind more tightly for the same reason: the reduced energy of hydration allows the net transfer energy (the well depth) to be more negative. This simple selectivity mechanism that governs permeability and binding acts to optimize the function of CFTR as a Cl filter. Anions that are smaller (more difficult to dehydrate) than Cl are energetically retarded from entering the channel, while the larger (more readily dehydrated) anions are retarded in their passage by “sticking” within the channel. PMID:10578016

  8. How to Measure Thermal Conductivity

    NASA Astrophysics Data System (ADS)

    Ventura, Guglielmo; Perfetti, Mauro

    The methods to measure the thermal conductivity at low temperature are described: the steady-state techniques, (Sect. 2.2 ); the 3ω technique (Sect. 2.3 ); and the thermal diffusivity measurement (Sect. 2.4 ). Each of these techniques has its own advantages as well as its inherent limitations, with some techniques more appropriate to specific sample geometry, such as the 3ω technique for thin films which is discussed in detail in Sect. 2.4.2 . The radial flux method is reported in Sect. 2.2.4 , the laser flash diffusivity method in Sect. 2.4.1 and the "pulsed power or Maldonado technique" in Sect. 2.3.2 .

  9. 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.

  10. 32 CFR 1903.14 - Disorderly conduct.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Disorderly conduct. 1903.14 Section 1903.14 National Defense Other Regulations Relating to National Defense CENTRAL INTELLIGENCE AGENCY CONDUCT ON AGENCY INSTALLATIONS § 1903.14 Disorderly conduct. A person commits disorderly conduct when, with...

  11. 32 CFR 1903.14 - Disorderly conduct.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Disorderly conduct. 1903.14 Section 1903.14 National Defense Other Regulations Relating to National Defense CENTRAL INTELLIGENCE AGENCY CONDUCT ON AGENCY INSTALLATIONS § 1903.14 Disorderly conduct. A person commits disorderly conduct when, with...

  12. 32 CFR 1903.14 - Disorderly conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Disorderly conduct. 1903.14 Section 1903.14 National Defense Other Regulations Relating to National Defense CENTRAL INTELLIGENCE AGENCY CONDUCT ON AGENCY INSTALLATIONS § 1903.14 Disorderly conduct. A person commits disorderly conduct when, with...

  13. 32 CFR 1903.14 - Disorderly conduct.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Disorderly conduct. 1903.14 Section 1903.14 National Defense Other Regulations Relating to National Defense CENTRAL INTELLIGENCE AGENCY CONDUCT ON AGENCY INSTALLATIONS § 1903.14 Disorderly conduct. A person commits disorderly conduct when, with...

  14. 32 CFR 1903.14 - Disorderly conduct.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Disorderly conduct. 1903.14 Section 1903.14 National Defense Other Regulations Relating to National Defense CENTRAL INTELLIGENCE AGENCY CONDUCT ON AGENCY INSTALLATIONS § 1903.14 Disorderly conduct. A person commits disorderly conduct when, with...

  15. 36 CFR 1002.34 - Disorderly conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Disorderly conduct. 1002.34... RECREATION § 1002.34 Disorderly conduct. (a) A person commits disorderly conduct when, with intent to cause... purpose of the actor's conduct, location, time of day or night, and other factors that would govern...

  16. 12 CFR 19.196 - Disreputable conduct.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Disreputable conduct. 19.196 Section 19.196... PROCEDURE Parties and Representational Practice Before the OCC; Standards of Conduct § 19.196 Disreputable conduct. Disreputable conduct for which an individual may be censured, debarred, or suspended...

  17. 32 CFR 234.7 - Disorderly conduct.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 2 2013-07-01 2013-07-01 false Disorderly conduct. 234.7 Section 234.7 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS CONDUCT ON THE PENTAGON RESERVATION § 234.7 Disorderly conduct. A person commits disorderly conduct...

  18. 32 CFR 234.7 - Disorderly conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 2 2010-07-01 2010-07-01 false Disorderly conduct. 234.7 Section 234.7 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS CONDUCT ON THE PENTAGON RESERVATION § 234.7 Disorderly conduct. A person commits disorderly conduct...

  19. 32 CFR 234.7 - Disorderly conduct.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 2 2012-07-01 2012-07-01 false Disorderly conduct. 234.7 Section 234.7 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS CONDUCT ON THE PENTAGON RESERVATION § 234.7 Disorderly conduct. A person commits disorderly conduct...

  20. 32 CFR 234.7 - Disorderly conduct.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 2 2011-07-01 2011-07-01 false Disorderly conduct. 234.7 Section 234.7 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS CONDUCT ON THE PENTAGON RESERVATION § 234.7 Disorderly conduct. A person commits disorderly conduct...

  1. 32 CFR 234.7 - Disorderly conduct.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 2 2014-07-01 2014-07-01 false Disorderly conduct. 234.7 Section 234.7 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED) MISCELLANEOUS CONDUCT ON THE PENTAGON RESERVATION § 234.7 Disorderly conduct. A person commits disorderly conduct...

  2. Making Conductive Polymers By Arc Tracking

    NASA Technical Reports Server (NTRS)

    Daech, Alfred F.

    1992-01-01

    Experimental technique for fabrication of electrically conductive polymeric filaments based on arc tracking, in which electrical arc creates conductive carbon track in material that initially was insulator. Electrically conductive polymeric structures made by arc tracking aligned along wire on which formed. Alignment particularly suited to high conductivity and desirable in materials intended for testing as candidate superconductors.

  3. Proton conducting membrane using a solid acid

    NASA Technical Reports Server (NTRS)

    Haile, Sossina M. (Inventor); Chisholm, Calum (Inventor); Boysen, Dane A. (Inventor); Narayanan, Sekharipuram R. (Inventor)

    2006-01-01

    A solid acid material is used as a proton conducting membrane in an electrochemical device. The solid acid material can be one of a plurality of different kinds of materials. A binder can be added, and that binder can be either a nonconducting or a conducting binder. Nonconducting binders can be, for example, a polymer or a glass. A conducting binder enables the device to be both proton conducting and electron conducting.

  4. Mechanism of conductance switching: An optical investigation

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Anirban; Chowdhury, Arabinda; Pal, Amlan J.

    2006-09-01

    Electronic conductance switching in devices based on thin films of an organic molecule has been studied. Switching between two conducting states has been induced by voltage pulse, while the states have been probed by optical and electrical measurements simultaneously. In situ optical measurements showed that electroreduction of molecules led to conductance switching and appearance of high-conducting state in the device. We could "write" or "erase" a state by applying electrical pulse and "read" it by measuring electronic absorbance and conductivity. The "write" and "read" processes have been carried out for many cycles to exhibit a correspondence between conductance switching and electrochromism.

  5. Electronically conductive polymer composites and microstructures

    SciTech Connect

    Van Dyke, L.S.

    1993-01-01

    Composites of electronically conductive polymers with insulating host materials are investigated. A template synthesis method was developed for the production of electronically conductive polymer microstructures. In template synthesis the pores of a porous host membrane act as templates for the polymerization of a conductive polymer. The template synthetic method can be used to form either solid microfibrils or hollow microtubules. The electrochemical properties of conductive polymers produced via the template synthesis method are superior to those of conventionally synthesized conductive polymers. Electronically conductive polymers are used to impart conductivity to non-conductive materials. Two different approaches are used. First, thin film composites of conductive polymers with fluoropolymers are made by the polymerization of conductive polymers onto fluoropolymer films. Modification of the fluoropolymer surface prior to conductive polymer polymerization is necessary to obtain good adhesion between the two materials. The difference in adhesion of the conductive polymer to the modified and unmodified fluoropolymer surfaces can be used to pattern the conductive polymer coating. Patterning of the conductive polymer coating can alternatively be done via UV laser ablation of the conductive polymer. The second method by which conductive polymers were used to impart conductivity to an insulating polymer was via the formation of a graft copolymer. In this approach, heterocyclic monomers grafted to an insulating polyphosphazene backbone were polymerized to yield semiconductive materials. Finally the measurement of electrolyte concentration in polypyrrole and the effects of hydroxide anion on the electrochemical and electrical properties of polypyrrole are described. It is shown that treatment of polypyrrole with hydroxide anion increases the potential window over which polypyrrole is a good electronic conductor.

  6. Electrical conductivity of Al-bearing bridgmanite

    NASA Astrophysics Data System (ADS)

    Yoshino, T.; Kamada, S.; Ohtani, E.; Hirao, N.

    2015-12-01

    Electrical conductivity measurements of bridgmanite with various Al contents and constant Mg# 90 at room temperature up to 2000 K and 26-28 GPa were performed in Kawai-type multianvil apparatus using impedance spectroscopic analyses. The incorporation of Al into bridgmanite significantly raises the electrical conductivity but it is small conductivity variation with respect to the amount of Al. Synchrotron Mössbauer spectroscopy of recovered samples showed a significant amount of ferric iron in aluminous bridgmanite. The mobility of charge carriers in bridgmanite was calculated from the conductivity and Fe3+/ΣFe. A relation between the logarithm of electrical conductivity and reciprocal temperature is consistent with Fe2+-Fe3+ electron hopping (small polaron) as the dominant conduction mechanism at low temperatures (< 1400 K) and ionic conduction at high temperatures (> 1600 K). Taking various conduction mechanisms into account, we develop an electrical conductivity model for aluminous bridgmanite as a function of Al and Fe content. This conductivity model suggests that the electrical conductivity of aluminous bridgmanite has a maximum at around 0.13 Al per formula unit, and further increase of Al in bridgmanite reduces the conductivity. The conductivity increase observed in the uppermost lower mantle by electromagnetic studies can be explained by increases of Fe and Na content in combination with substitution of Al into bridgmanite with increasing pressure due to the gradual decomposition of majorite garnet.

  7. 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.

  8. Investigation of electrostatic discharge phenomena on conductive and non-conductive solar reflectors

    NASA Technical Reports Server (NTRS)

    Bosma, S. J.; Minier, C. F.; Levy, L.

    1979-01-01

    A sample composed of non conductive optical solar reflectors (OSR) was irradiated with low energy electrons at the DERTS facility to study the effects of charge build up on thermal control coating materials. The degration effects on this panel due to electrostatic discharges were investigated to find possible alternatives to limit the amount of damage. The following systems are evaluated: (1) non conductive OSR (non conductive adhesive) (2) non conductive OSR (conductive adhesive); and conductive OSR (conductive adhesive).

  9. Molecular electronics: A DNA that conducts

    NASA Astrophysics Data System (ADS)

    Scheer, Elke

    2014-12-01

    Experiments with conducting atomic force microscopy provide a clear demonstration of long-range charge transport in G-quadruplex DNA molecules, and allow a hopping transport model to be developed that could also be applied to other conductive polymers.

  10. Thermal conductance of multilayered metallic sheets

    NASA Astrophysics Data System (ADS)

    Fletcher, L. S.; Blanchard, D. G.; Kinnear, K. P.

    1991-06-01

    An experimental investigation was conducted to determine the thermal conductivity, the overall thermal conductance, and the thermal contact conductance between layers of stacked aluminum alloy 3004, 5042, and 5182 sheet. Tests were conducted for aluminum sample thicknesses of 0.0305 to 0.3074 cm (0.012 to 0.121 in.), mean junction temperatures of 79.5 and 165.5 C (175 and 330 F), and contact pressures of 0.689 to 10.34 MPa (100 to 1500 psi). The overall thermal conductance increased with increasing contact pressure and increasing temperature. It decreased as the number of aluminum layers was increased. The experimental data were used to derive thermal contact conductance between layers of stacked aluminum sheet. From these derived values, a correlation for the thermal contact conductance was developed. The resulting expressions are presented as a function of dimensionless parameters for the layer material, apparent contact pressure, and mean junction temperature.

  11. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, William E.

    1984-01-01

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  12. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, W.E.

    1982-09-30

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  13. Ionic conduction in polymer composite electrolytes

    NASA Astrophysics Data System (ADS)

    Dam, Tapabrata; Tripathy, Satya N.; Paluch, M.; Jena, S.; Pradhan, D. K.

    2016-05-01

    Conductivity and structural relaxation has been explored from modulus and dielectric loss formalisms respectively for a series of polymer composite electrolytes with zirconia as filler. The temperature dependence of conductivity followed Vogel-Tamman-Fulcher (VTF) behavior, which suggested a close correlation between conductivity and the segmental relaxation process in polymer electrolytes. Vogel temperature (T0) plays significant role in ion conduction process in these kind of materials.

  14. Synthetic Biological Protein Nanowires with High Conductivity.

    PubMed

    Tan, Yang; Adhikari, Ramesh Y; Malvankar, Nikhil S; Pi, Shuang; Ward, Joy E; Woodard, Trevor L; Nevin, Kelly P; Xia, Qiangfei; Tuominen, Mark T; Lovley, Derek R

    2016-09-01

    Genetic modification to add tryptophan to PilA, the monomer for the electrically conductive pili of Geobacter sulfurreducens, yields conductive protein filaments 2000-fold more conductive than the wild-type pili while cutting the diameter in half to 1.5 nm. PMID:27409066

  15. 12 CFR 13.3 - Business conduct.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Business conduct. 13.3 Section 13.3 Banks and....3 Business conduct. A bank that is a government securities broker or dealer shall observe high standards of commercial honor and just and equitable principles of trade in the conduct of its business as...

  16. 12 CFR 13.3 - Business conduct.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Business conduct. 13.3 Section 13.3 Banks and....3 Business conduct. A bank that is a government securities broker or dealer shall observe high standards of commercial honor and just and equitable principles of trade in the conduct of its business as...

  17. 12 CFR 368.3 - Business conduct.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 5 2012-01-01 2012-01-01 false Business conduct. 368.3 Section 368.3 Banks and... SECURITIES SALES PRACTICES § 368.3 Business conduct. A bank that is a government securities broker or dealer... conduct of its business as a government securities broker or dealer....

  18. 12 CFR 368.3 - Business conduct.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 4 2011-01-01 2011-01-01 false Business conduct. 368.3 Section 368.3 Banks and... SECURITIES SALES PRACTICES § 368.3 Business conduct. A bank that is a government securities broker or dealer... conduct of its business as a government securities broker or dealer....

  19. 12 CFR 13.3 - Business conduct.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Business conduct. 13.3 Section 13.3 Banks and....3 Business conduct. A bank that is a government securities broker or dealer shall observe high standards of commercial honor and just and equitable principles of trade in the conduct of its business as...

  20. 12 CFR 13.3 - Business conduct.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Business conduct. 13.3 Section 13.3 Banks and....3 Business conduct. A bank that is a government securities broker or dealer shall observe high standards of commercial honor and just and equitable principles of trade in the conduct of its business as...

  1. 12 CFR 368.3 - Business conduct.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 5 2014-01-01 2014-01-01 false Business conduct. 368.3 Section 368.3 Banks and... SECURITIES SALES PRACTICES § 368.3 Business conduct. A bank that is a government securities broker or dealer... conduct of its business as a government securities broker or dealer....

  2. 12 CFR 368.3 - Business conduct.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 5 2013-01-01 2013-01-01 false Business conduct. 368.3 Section 368.3 Banks and... SECURITIES SALES PRACTICES § 368.3 Business conduct. A bank that is a government securities broker or dealer... conduct of its business as a government securities broker or dealer....

  3. The Workshop on Conductive Polymers: Final Report

    DOE R&D Accomplishments Database

    1985-10-01

    Reports are made by groups on: polyacetylene, polyphenylene, polyaniline, and related systems; molecular, crystallographic, and defect structures in conducting polymers; heterocyclic polymers; synthesis of new and improved conducting polymers; future applications possibilities for conducting polymers; and challenges for improved understanding of properties. (DLC)

  4. The workshop on conductive polymers: Final report

    SciTech Connect

    Not Available

    1985-01-01

    Reports are made by groups on: polyacetylene, polyphenylene, polyaniline, and related systems; molecular, crystallographic, and defect structures in conducting polymers; heterocyclic polymers; synthesis of new and improved conducting polymers; future applications possibilities for conducting polymers; and challenges for improved understanding of properties. (DLC)

  5. Organic conductive films for semiconductor electrodes

    DOEpatents

    Frank, A.J.

    1984-01-01

    According to the present invention, improved electrodes overcoated with conductive polymer films and preselected catalysts are provided. The electrodes typically comprise an inorganic semiconductor over-coated with a charge conductive polymer film comprising a charge conductive polymer in or on which is a catalyst or charge-relaying agent.

  6. The hydraulic conductivity of chopped sorghum

    SciTech Connect

    Custer, M.H.; Reddell, D.L.; Sweeten, J.M.

    1987-01-01

    Hydraulic conductivity of water through chopped sweet sorghum at various packing densities and soaking times was measured using permeameters. Hydraulic conductivity decreased by two orders of magnitude as packing density increased from 400 to 897 kg/m/sup 3/. Soaking time had less effect on hydraulic conductivity, and the effect depended on packing density.

  7. 45 CFR 81.111 - Conduct.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Conduct. 81.111 Section 81.111 Public Welfare... 80 OF THIS TITLE Judicial Standards of Practice § 81.111 Conduct. Parties and their representatives are expected to conduct themselves with honor and dignity and observe judicial standards of...

  8. 34 CFR 101.111 - Conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Conduct. 101.111 Section 101.111 Education Regulations of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION... Conduct. Parties and their representatives are expected to conduct themselves with honor and dignity...

  9. 38 CFR 18b.90 - Conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Conduct. 18b.90 Section 18b.90 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS (CONTINUED) PRACTICE AND... Practice § 18b.90 Conduct. Parties and their representatives are expected to conduct themselves with...

  10. 14 CFR 300.5 - Prohibited conduct.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Prohibited conduct. 300.5 Section 300.5 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) PROCEDURAL REGULATIONS RULES OF CONDUCT IN DOT PROCEEDINGS UNDER THIS CHAPTER § 300.5 Prohibited conduct. No person...

  11. 17 CFR 200.56 - Personal conduct.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Personal conduct. 200.56 Section 200.56 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION ORGANIZATION; CONDUCT AND ETHICS; AND INFORMATION AND REQUESTS Canons of Ethics § 200.56 Personal conduct. Appointment...

  12. 36 CFR 2.34 - Disorderly conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Disorderly conduct. 2.34... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.34 Disorderly conduct. (a) A person commits disorderly conduct when, with intent to cause public alarm, nuisance, jeopardy or violence, or knowingly...

  13. 7 CFR 1485.28 - Ethical conduct.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...., 7 CFR Parts 1485, 3015, 3016, 3018, 3021, 3019, and 3052). (b) Except for a U.S. agricultural... 7 Agriculture 10 2013-01-01 2013-01-01 false Ethical conduct. 1485.28 Section 1485.28 Agriculture... COMMODITIES Market Access Program § 1485.28 Ethical conduct. (a) A MAP Participant shall conduct its...

  14. 7 CFR 1485.28 - Ethical conduct.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...., 7 CFR Parts 1485, 3015, 3016, 3018, 3021, 3019, and 3052). (b) Except for a U.S. agricultural... 7 Agriculture 10 2014-01-01 2014-01-01 false Ethical conduct. 1485.28 Section 1485.28 Agriculture... COMMODITIES Market Access Program § 1485.28 Ethical conduct. (a) A MAP Participant shall conduct its...

  15. Organic conductive films for semiconductor electrodes

    DOEpatents

    Frank, Arthur J.

    1984-01-01

    According to the present invention, improved electrodes overcoated with conductive polymer films and preselected catalysts are provided. The electrodes typically comprise an inorganic semiconductor overcoated with a charge conductive polymer film comprising a charge conductive polymer in or on which is a catalyst or charge-relaying agent.

  16. 12 CFR 13.3 - Business conduct.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Business conduct. 13.3 Section 13.3 Banks and....3 Business conduct. A bank that is a government securities broker or dealer shall observe high standards of commercial honor and just and equitable principles of trade in the conduct of its business as...

  17. 12 CFR 368.3 - Business conduct.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 4 2010-01-01 2010-01-01 false Business conduct. 368.3 Section 368.3 Banks and... SECURITIES SALES PRACTICES § 368.3 Business conduct. A bank that is a government securities broker or dealer... conduct of its business as a government securities broker or dealer....

  18. Mixed ionic and electronic conductivity in polymers

    SciTech Connect

    Shriver, D.F.

    1990-06-01

    The conductivity of iodine-containing polymers was investigated and conductivity along polyiodide chains is implicated by the concentration dependence of the conductivity data and spectroscopic measurements. On the theoretical side, entropy based models were developed to describe ion motion in polymers.

  19. 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.

  20. Proton conducting membrane using a solid acid

    NASA Technical Reports Server (NTRS)

    Chisholm, Calum (Inventor); Narayanan, Sekharipuram R. (Inventor); Boysen, Dane (Inventor); Haile, Sossina M. (Inventor)

    2002-01-01

    A solid acid material is used as a proton conducting membrane in an electrochemical device. The solid acid material can be one of a plurality of different kinds of materials. A binder can be added, and that binder can be either a nonconducting or a conducting binder. Nonconducting binders can be, for example, a polymer or a glass. A conducting binder enables the device to be both proton conducting and electron conducting. The solid acid material has the general form M.sub.a H.sub.b (XO.sub.t).sub.c.

  1. Conductance Studies of Aqueous Succinic Acid

    NASA Astrophysics Data System (ADS)

    Apelblat, Alexander; Barthel, Josef

    1992-03-01

    Conductance measurements of aqueous solutions of succinic acid and of di-sodium succinate were performed from 278.15 to 308.15 K and the limiting conductances λ0 (1/2 Succ2- ) are reported. The Waiden product is independent of temperature: λ0(1/2 Succ2-)*η(T) = 0.503 ± 0.001. The salt conductances closely obey the Onsager limiting law. The evaluation of the equilibrium constants for the primary and secondary steps of dissociation, K1 and K2, and the limiting conductances of the hydrosuccinate ion, λ0(HSucc-), are discussed using the Quint and Viallard conductance equation

  2. Suppressed conductance in a metallic graphene nanojunction

    NASA Astrophysics Data System (ADS)

    Li, Haidong; Wang, Lin; Zheng, Yisong

    2009-01-01

    The linear conductance spectrum of a metallic graphene junction formed by interconnecting two gapless graphene nanoribbons is calculated. A strong conductance suppression appears in the vicinity of the Dirac point. We found that such a conductance suppression arises from the antiresonance effect associated with an edge state localized at the zigzag-edged shoulder of the junction. The conductance valley due to the antiresonance is rather robust in the presence of the impurity and vacancy scattering. Also the center of the conductance valley can be readily tuned by an electric field exerted on the wider nanoribbon.

  3. Thermal conductivity of sputtered amorphous Ge films

    SciTech Connect

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

    2014-02-15

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids.

  4. The symmetry of single-molecule conduction.

    PubMed

    Solomon, Gemma C; Gagliardi, Alessio; Pecchia, Alessandro; Frauenheim, Thomas; Di Carlo, Aldo; Reimers, Jeffrey R; Hush, Noel S

    2006-11-14

    We introduce the conductance point group which defines the symmetry of single-molecule conduction within the nonequilibrium Green's function formalism. It is shown, either rigorously or to within a very good approximation, to correspond to a molecular-conductance point group defined purely in terms of the properties of the conducting molecule. This enables single-molecule conductivity to be described in terms of key qualitative chemical descriptors that are independent of the nature of the molecule-conductor interfaces. We apply this to demonstrate how symmetry controls the conduction through 1,4-benzenedithiol chemisorbed to gold electrodes as an example system, listing also the molecular-conductance point groups for a range of molecules commonly used in molecular electronics research. PMID:17115774

  5. 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.

  6. Regulation of conduction time along axons.

    PubMed

    Seidl, A H

    2014-09-12

    Timely delivery of information is essential for proper functioning of the nervous system. Precise regulation of nerve conduction velocity is needed for correct exertion of motor skills, sensory integration and cognitive functions. In vertebrates, the rapid transmission of signals along nerve fibers is made possible by the myelination of axons and the resulting saltatory conduction in between nodes of Ranvier. Myelin is a specialization of glia cells and is provided by oligodendrocytes in the central nervous system. Myelination not only maximizes conduction velocity, but also provides a means to systematically regulate conduction times in the nervous system. Systematic regulation of conduction velocity along axons, and thus systematic regulation of conduction time in between neural areas, is a common occurrence in the nervous system. To date, little is understood about the mechanism that underlies systematic conduction velocity regulation and conduction time synchrony. Node assembly, internode distance (node spacing) and axon diameter - all parameters determining the speed of signal propagation along axons - are controlled by myelinating glia. Therefore, an interaction between glial cells and neurons has been suggested. This review summarizes examples of neural systems in which conduction velocity is regulated by anatomical variations along axons. While functional implications in these systems are not always clear, recent studies on the auditory system of birds and mammals present examples of conduction velocity regulation in systems with high temporal precision and a defined biological function. Together these findings suggest an active process that shapes the interaction between axons and myelinating glia to control conduction velocity along axons. Future studies involving these systems may provide further insight into how specific conduction times in the brain are established and maintained in development. Throughout the text, conduction velocity is used for the

  7. Sensitive bridge circuit measures conductance of low-conductivity electrolyte solutions

    NASA Technical Reports Server (NTRS)

    Schmidt, K.

    1967-01-01

    Compact bridge circuit measures sensitive and accurate conductance of low-conductivity electrolyte solutions. The bridge utilizes a phase sensitive detector to obtain a linear deflection of the null indicator relative to the measured conductance.

  8. Local Conductance and Saturation Lengths of Atomic Wires Dipped in a Conducting Medium

    NASA Technical Reports Server (NTRS)

    OKeeffe, James; Mingo, Natalio; Han, Jie; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    We conclude that the conducting mode pi is the most likely responsible for conduction in experimental mercury-nanotube contacts. The total conductance approaches a saturation value as the dipping length is increased. There are two distinct regimes, strong and weak coupling, characterized by saturation conductances of 0 or 1G(sub o). We have calculated the partial conductance at each nanotube unit cell. The partial conductance exhibits oscillations due to reflection at the end of the tube.

  9. Universal thermal and electrical conductivity from holography

    NASA Astrophysics Data System (ADS)

    Jain, Sachin

    2010-11-01

    It is known from earlier work of Iqbal, Liu [1] 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 thermodynamic quantities. We also consider the theory at finite cutoff recently constructed in [2], at radius r c outside the horizon and give an expression for cutoff dependent electrical conductivity ( σ( r c )), which interpolates smoothly between horizon conductivity σ H ( r c → r h ) and boundary conductivity σ B ( r c → ∞). Using the results about the conductivity we gain much insight into the universality of thermal conductivity to viscosity ratio proposed in [3].

  10. Effective Thermal Conductivity of Corrugated Insulating Materials

    NASA Astrophysics Data System (ADS)

    Yamada, Etsuro; Kato, Masayasu; Tomikawa, Takayuki; Takahashi, Kaneko

    The effective thermal conductivity of corrugated insulating materials which are made by polypropylene or polycarbonate have been measured by employing steady state comparison method for several specimen having various thickness and specific weight. The thermal conductivity of them evaluated are also by using the thermal resistance models, and are compared with above measured values and raw materials' conductivity. The main results obtained in this paper are as follows: (1) In regard to the specimen in this paper, the effective thermal conductivity increases with increasing temperature, but the increasing rate of them is small. (2) There are considerable differences between the measured values and the predicted ones that are estimated by using the thermal resistance model in which heat flow by conduction only. This differences increase with increasing specimens' thickness. This difference become extinct by considering the coexistence heat flow of conduction and radiation in the air phase of specimen. (3) The thermal resistance of specimen increases linearly with increasing specimens' thickness.

  11. 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.

  12. Thermal conductivity analysis of lanthanum doped manganites

    SciTech Connect

    Mansuri, Irfan; Shaikh, M. W.; Khan, E.; Varshney, Dinesh

    2014-04-24

    The temperature-dependent thermal conductivity of the doped manganites La{sub 0.7}Ca{sub 0.3}MnO{sub 3} is theoretically analyzed within the framework of Kubo formulae. The Hamiltonian consists of phonon, electron and magnon thermal conductivity contribution term. In this process we took defects, carrier, grain boundary, scattering process term and then calculate phonon, electron and magnon thermal conductivity.

  13. Thermal conductivity of nanostructured boron nitride materials.

    PubMed

    Tang, Chengchun; Bando, Yoshio; Liu, Changhong; Fan, Shoushan; Zhang, Jun; Ding, Xiaoxia; Golberg, Dmitri

    2006-06-01

    We have measured the thermal conductivity of bulky pellets made of various boron nitride (BN)-based nanomaterials, including spherical nanoparticles, perfectly structured, bamboo-like nanotubes, and collapsed nanotubes. The thermal conductivity strongly depends on the morphology of the BN nanomaterials, especially on the surface structure. Spherical BN particles have the lowest thermal conductivity while the collapsed BN nanotubes possess the best thermoconductive properties. A model was proposed to explain the experimental observations based on the heat percolation passage considerations. PMID:16722739

  14. Cascade solar cell having conductive interconnects

    DOEpatents

    Borden, Peter G.; Saxena, Ram R.

    1982-10-26

    Direct ohmic contact between the cells in an epitaxially grown cascade solar cell is obtained by means of conductive interconnects formed through grooves etched intermittently in the upper cell. The base of the upper cell is directly connected by the conductive interconnects to the emitter of the bottom cell. The conductive interconnects preferably terminate on a ledge formed in the base of the upper cell.

  15. Anisotropic Thermal Conductivity of Exfoliated Black Phosphorus.

    PubMed

    Jang, Hyejin; Wood, Joshua D; Ryder, Christopher R; Hersam, Mark C; Cahill, David G

    2015-12-22

    The anisotropic thermal conductivity of passivated black phosphorus (BP), a reactive two-dimensional material with strong in-plane anisotropy, is ascertained. The room-temperature thermal conductivity for three crystalline axes of exfoliated BP is measured by time-domain thermo-reflectance. The thermal conductivity along the zigzag direction is ≈2.5 times higher than that of the armchair direction. PMID:26516073

  16. Model for heat conduction in nanofluids.

    PubMed

    Kumar, D Hemanth; Patel, Hrishikesh E; Kumar, V R Rajeev; Sundararajan, T; Pradeep, T; Das, Sarit K

    2004-10-01

    A comprehensive model has been proposed to account for the large enhancement of thermal conductivity in nanofluids and its strong temperature dependence, which the classical Maxwellian theory has been unable to explain. The dependence of thermal conductivity on particle size, concentration, and temperature has been taken care of simultaneously in our treatment. While the geometrical effect of an increase in surface area with a decrease in particle size, rationalized using a stationary particle model, accounts for the conductivity enhancement, a moving particle model developed from the Stokes-Einstein formula explains the temperature effect. Predictions from the combined model agree with the experimentally observed values of conductivity enhancement of nanofluids. PMID:15524799

  17. Morphology in electrochemically grown conducting polymer films

    DOEpatents

    Rubinstein, Israel; Gottesfeld, Shimshon; Sabatani, Eyal

    1992-01-01

    A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventioonally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol.

  18. Using Telemedicine to Conduct Behavioral Assessments

    PubMed Central

    Barretto, Anjali; Wacker, David P; Harding, Jay; Lee, John; Berg, Wendy K

    2006-01-01

    We describe the use of telemedicine by the Biobehavioral Service at the University of Iowa Hospitals and Clinics to conduct brief functional analyses for children with developmental and behavioral disorders who live in rural areas of Iowa. Instead of being served at our outpatient facility, participants received initial behavioral assessments in their local schools or social service agencies via videoconference. Case descriptions for 2 participants whose evaluations were conducted via telemedicine, and a brief summary of all outpatient assessments conducted over a 4-year period by the Biobehavioral Service, are provided. This report extends previous applications of functional analysis procedures by examining brief behavioral assessments conducted via telemedicine. PMID:17020213

  19. Are Kohn-Sham conductances accurate?

    PubMed

    Mera, H; Niquet, Y M

    2010-11-19

    We use Fermi-liquid relations to address the accuracy of conductances calculated from the single-particle states of exact Kohn-Sham (KS) density functional theory. We demonstrate a systematic failure of this procedure for the calculation of the conductance, and show how it originates from the lack of renormalization in the KS spectral function. In certain limits this failure can lead to a large overestimation of the true conductance. We also show, however, that the KS conductances can be accurate for single-channel molecular junctions and systems where direct Coulomb interactions are strongly dominant. PMID:21231333

  20. Morphology in electrochemically grown conducting polymer films

    DOEpatents

    Rubinstein, I.; Gottesfeld, S.; Sabatani, E.

    1992-04-28

    A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventionally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol. 2 figs.

  1. Conductive ink containing thermally exfoliated graphite oxide and method a conductive circuit using the same

    NASA Technical Reports Server (NTRS)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)

    2011-01-01

    A conductive ink containing a conductive polymer, wherein the conductive polymer contains at least one polymer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, and it use in a method for making a conductive circuit.

  2. HYDRAULIC CONDUCTIVITY OF ESSENTIALLY SATURATED PEAT

    SciTech Connect

    Nichols, R

    2008-02-27

    The Savannah River National Laboratory measured the hydraulic conductivity of peat samples using method ASTM D4511-00. Four samples of peat were packed into 73mm diameter plastic tubes and saturated from the bottom up with water. The columns were packed with Premier ProMoss III TBK peat to a dry density of approximately 0.16 gm/cc (10 lb/ft3). One column was packed using oven dried peat and the other 3 were packed using as delivered peat. The oven dried sample was the most difficult to saturate. All of the peat samples expanded during saturation resulting in a sample length (L) that was longer than when the sample was initially packed. Table 1 contains information related to the column packing. After saturation the hydraulic conductivity test was conducted using the apparatus shown in Figure 1. Three of the samples were tested at 2 different flow conductions, 1 high and 1 low. Table 2 and Figure 2 contain the results of the hydraulic conductivity testing. Each test was run for a minimum of 40 minutes to allow the test conditions to stabilize. The hydraulic conductivity at the end of each test is reported as the hydraulic conductivity for that test. The hydraulic conductivity of the 4 peat samples is 0.0052 {+-} 0.0009 cm/sec. This result compares well with the hydraulic conductivity measured in the pilot scale peat bed after approximately 2 months of operation. The similarity in results between the dry pack sample and moist pack samples shows the moisture content at the time of packing had a minimal effect on the hydraulic conductivity. Additionally, similarity between the results shows the test is reproducible. The hydraulic conductivity results are similar to those reported by other tests of peat samples reported in the literature.

  3. Electrically conductive fibers thermally isolate temperature sensor

    NASA Technical Reports Server (NTRS)

    De Waard, R.; Norton, B.

    1966-01-01

    Mounting assembly provides thermal isolation and an electrical path for an unbacked thermal sensor. The sensor is suspended in the center of a plastic mounting ring from four plastic fibers, two of which are coated with an electrically conductive material and connected to electrically conductive coatings on the ring.

  4. Method of making conductive elastomer connector

    NASA Technical Reports Server (NTRS)

    Alonso, Oscar (Inventor)

    1980-01-01

    An electrical connector in which conductive rubber rods are mounted in a metal substrate covered by a nonconductive layer. The rods extend above and below the upper and lower surfaces, respectively, of the substrate for electrically interconnecting conductive traces on a pair of electronic components. A method for making the connector is disclosed.

  5. The Complexities of Conducting Ethnographic Race Research

    ERIC Educational Resources Information Center

    Klaas, Jongi

    2006-01-01

    This paper explores the challenges and dilemmas of conducting ethnographic race research in the context of the South African situation, forming part of my ethnographic race research PhD project, conducted in two historically white, single-sex schools in South Africa. First, it critically examines the theoretical dilemmas on crucial issues of…

  6. Flexible moldable conductive current-limiting materials

    DOEpatents

    Shea, John Joseph; Djordjevic, Miomir B.; Hanna, William Kingston

    2002-01-01

    A current limiting PTC device (10) has two electrodes (14) with a thin film of electric conducting polymer material (20) disposed between the electrodes, the polymer material (20) having superior flexibility and short circuit performance, where the polymer material contains short chain aliphatic diepoxide, conductive filler particles, curing agent, and, preferably, a minor amount of bisphenol A epoxy resin.

  7. An Innovative High Thermal Conductivity Fuel Design

    SciTech Connect

    Jamil A. Khan

    2009-11-21

    Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 [97% TD]. This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

  8. 47 CFR 97.511 - Examinee conduct.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Examinee conduct. 97.511 Section 97.511 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Qualifying Examination Systems § 97.511 Examinee conduct. Each examinee must comply with...

  9. 47 CFR 97.511 - Examinee conduct.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Examinee conduct. 97.511 Section 97.511 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Qualifying Examination Systems § 97.511 Examinee conduct. Each examinee must comply with...

  10. 47 CFR 97.511 - Examinee conduct.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Examinee conduct. 97.511 Section 97.511 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Qualifying Examination Systems § 97.511 Examinee conduct. Each examinee must comply with...

  11. 47 CFR 97.511 - Examinee conduct.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Examinee conduct. 97.511 Section 97.511 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Qualifying Examination Systems § 97.511 Examinee conduct. Each examinee must comply with...

  12. 47 CFR 97.511 - Examinee conduct.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Examinee conduct. 97.511 Section 97.511 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Qualifying Examination Systems § 97.511 Examinee conduct. Each examinee must comply with...

  13. 47 CFR 18.307 - Conduction limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Conduction limits. 18.307 Section 18.307 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.307 Conduction limits. For the following equipment, when designed to be connected to...

  14. 47 CFR 18.307 - Conduction limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Conduction limits. 18.307 Section 18.307 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.307 Conduction limits. For the following equipment, when designed to be connected to...

  15. 47 CFR 18.307 - Conduction limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Conduction limits. 18.307 Section 18.307 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.307 Conduction limits. For the following equipment, when designed to be connected to...

  16. 47 CFR 18.307 - Conduction limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Conduction limits. 18.307 Section 18.307 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.307 Conduction limits. For the following equipment, when designed to be connected to...

  17. 47 CFR 18.307 - Conduction limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Conduction limits. 18.307 Section 18.307 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.307 Conduction limits. For the following equipment, when designed to be connected to...

  18. Conductive elastomers by a new latex process

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electrically conductive polymers such as polyaniline can be used to in production of light-emitting diodes, printed circuit board components, antistatic materials, etc. Highly filled elastomers, such as those filled with metallic powders, can also conduct electricity. However, limitations due to co...

  19. Transforming Hierarchical Relationships in Student Conduct Administration

    ERIC Educational Resources Information Center

    Jacobson, Kelly A.

    2013-01-01

    Conflict transformation theory provided a philosophical lens for this critical cultural, constructivist study, wherein four student conduct administrators who engage in leveling hierarchical relationships with students in conduct processes shared ways they make meaning of their professional practice. Through informal, unstructured interviews, a…

  20. Liquid crystal-templated conducting organic polymers

    DOEpatents

    Stupp, Samuel I.; Hulvat, James F.

    2004-01-20

    A method of preparing a conductive polymeric film, includes providing a liquid crystal phase comprising a plurality of hydrophobic cores, the phase on a substrate, introducing a hydrophobic component to the phase, the component a conductive polymer precursor, and applying an electric potential across the liquid crystal phase, the potential sufficient to polymerize the said precursor.

  1. 47 CFR 15.315 - Conducted limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Conducted limits. 15.315 Section 15.315 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Unlicensed Personal Communications Service Devices § 15.315 Conducted limits. An unlicensed PCS device that is designed to be connected to the public utility (AC) power...

  2. 47 CFR 15.315 - Conducted limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Conducted limits. 15.315 Section 15.315 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Unlicensed Personal Communications Service Devices § 15.315 Conducted limits. An unlicensed PCS device that is designed to...

  3. 47 CFR 15.315 - Conducted limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Conducted limits. 15.315 Section 15.315 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Unlicensed Personal Communications Service Devices § 15.315 Conducted limits. An unlicensed PCS device that is designed to...

  4. 47 CFR 15.315 - Conducted limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Conducted limits. 15.315 Section 15.315 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Unlicensed Personal Communications Service Devices § 15.315 Conducted limits. An unlicensed PCS device that is designed to...

  5. Dysgraphia in Two Forms of Conduction Aphasia

    ERIC Educational Resources Information Center

    Balasubramanian, V.

    2005-01-01

    Recent clinical observations, in the absence of experimental data, appear to suggest that written expression in conduction aphasics parallels their speech (Goodglass, 1992). The current study undertakes an analysis of word level writing in two conduction aphasics, and attempts to explore the posited 'parallel' relationship between speech…

  6. Conduct Disorders: Are Boot Camps Effective?

    ERIC Educational Resources Information Center

    Jeter, LaVaughn V.

    2010-01-01

    Youth diagnosed with "conduct disorder" are often placed in programs using forced compliance and coercive control. One type of intervention used to treat conduct disorder is the boot camp. The basic idea is that disruptive behaviors can be corrected by strict behavioral regulation and an emphasis on skills training (Weis & Toolis 2009; Weis,…

  7. 17 CFR 31.5 - Unlawful conduct.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Unlawful conduct. 31.5 Section 31.5 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION LEVERAGE TRANSACTIONS § 31.5 Unlawful conduct. (a) On and after April 13, 1984, it shall be unlawful for any person: (1)...

  8. 32 CFR 776.5 - Judicial conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... part, the American Bar Association's Code of Judicial Conduct applies to all military and appellate... 32 National Defense 5 2010-07-01 2010-07-01 false Judicial conduct. 776.5 Section 776.5 National Defense Department of Defense (Continued) DEPARTMENT OF THE NAVY MISCELLANEOUS RULES PROFESSIONAL...

  9. 45 CFR 81.112 - Improper conduct.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Improper conduct. 81.112 Section 81.112 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PRACTICE AND PROCEDURE FOR HEARINGS UNDER PART 80 OF THIS TITLE Judicial Standards of Practice § 81.112 Improper conduct. With respect...

  10. 34 CFR 101.112 - Improper conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Improper conduct. 101.112 Section 101.112 Education Regulations of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION... Improper conduct. With respect to any proceeding it is improper for any interested person to attempt...

  11. 36 CFR 261.4 - Disorderly conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Disorderly conduct. 261.4 Section 261.4 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE PROHIBITIONS General Prohibitions § 261.4 Disorderly conduct. The following are prohibited: (a) Engaging in...

  12. 38 CFR 18b.91 - Improper conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Improper conduct. 18b.91 Section 18b.91 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS (CONTINUED) PRACTICE... Standards of Practice § 18b.91 Improper conduct. With respect to any proceeding it is improper for...

  13. Proton conducting membrane for fuel cells

    DOEpatents

    Colombo, Daniel G.; Krumpelt, Michael; Myers, Deborah J.; Kopasz, John P.

    2007-03-27

    An ion conducting membrane comprising dendrimeric polymers covalently linked into a network structure. The dendrimeric polymers have acid functional terminal groups and may be covalently linked via linking compounds, cross-coupling reactions, or copolymerization reactions. The ion conducting membranes may be produced by various methods and used in fuel cells.

  14. Proton conducting membrane for fuel cells

    DOEpatents

    Colombo, Daniel G.; Krumpelt, Michael; Myers, Deborah J.; Kopasz, John P.

    2005-12-20

    An ion conducting membrane comprising dendrimeric polymers covalently linked into a network structure. The dendrimeric polymers have acid functional terminal groups and may be covalently linked via linking compounds, cross-coupling reactions, or copolymerization reactions. The ion conducting membranes may be produced by various methods and used in fuel cells.

  15. Lorenz number of conducting PEDOT:PSS

    NASA Astrophysics Data System (ADS)

    Wang, Xiaojia; Coates, Nelson; Segalman, Rachel; Cahill, David

    2014-03-01

    The electronic thermal conductivity is related to the electrical conductivity through the Wiedemann-Franz law (WFL), which predicts that the ratio of the electronic thermal conductivity to the electrical conductivity is proportional to the absolute temperature. The WFL has been validated for various materials; however, deviations may arise under certain circumstances, in which the relaxation times for the electrical and thermal processes are not identical. In this work, we investigate the Lorenz number, the proportionality factor in the WFL, of conjugated polymers. We prepare samples made of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with tunable electrical conductivity. The in-plane electrical resistivity is characterized with setups of both 4-point probe and Van der Pauw configurations. To determine the thermal conductivity along the same direction as that for the electrical resistivity, we measure the through-plane thermal conductivity of the cross section of PEDOT:PSS using time-domain thermoreflectance. The effects of anisotropy and inhomogeneity on the thermal conductivity of PEDOT:PSS are also examined. This work is supported by AFOSR MURI FA9550-12-1-0002.

  16. 76 FR 15856 - Standards of Conduct

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-22

    ... INFORMATION: A. Background The General Services Administration (GSA) published a final rule at 61 FR 56399... ADMINISTRATION 41 CFR Part 105-735 RIN 3090-AJ10 Standards of Conduct AGENCY: General Services Administration... standards of conduct. DATES: Effective Date: This final rule is effective March 22, 2011. FOR...

  17. 76 FR 70322 - Standards of Conduct

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-14

    ..., comprehensive, and clear set of executive-branch standards of conduct.'' E.O. 12674, 54 FR 15159, 15160 (Apr. 12, 1989). This Executive Order was later modified. E.O. 12731, 55 FR 42547 (Oct. 17, 1990). OGE's... Federal Register. See Notice of Proposed Rulemaking on Standards of Conduct, 75 FR 27456 (May 17,...

  18. 47 CFR 15.315 - Conducted limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Conducted limits. 15.315 Section 15.315 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Unlicensed Personal Communications Service Devices § 15.315 Conducted limits. An unlicensed PCS device that is designed to be connected to the public utility (AC) power...

  19. Action Research: Conducting Activities for Third Graders.

    ERIC Educational Resources Information Center

    James, Lorinda

    1998-01-01

    Discusses the action research conducted on whether the use of conducting patterns will not only help students understand meter, but also assist them in grasping certain expressive qualities of music. Finds that the posttest showed a 10 percent gain overall in the understanding of meter, tempo, dynamics, and style. (CMK)

  20. Conductance of AFM Deformed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Svizhenko, Alexei; Maiti, Amitesh; Anatram, M. P.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on the electrical conductivity of carbon nanotubes upon deformation by atomic force microscopy (AFM). The density of states and conductance were computed using four orbital tight-binding method with various parameterizations. Different chiralities develop bandgap that varies with chirality.

  1. Skin Conductance Measurement in Communication Research.

    ERIC Educational Resources Information Center

    Goodman, R. Irwin

    1985-01-01

    Describes skin conductance measurement as a physiological procedure to obtain information on onset, duration, intensity, and completion of private physiological responses to parts of films or media products. The mechanics of the technique, how measurements are recorded and analyzed, and types of skin conductance research literature are discussed.…

  2. Conduct Systems Designed to Promote Moral Learning

    ERIC Educational Resources Information Center

    Lancaster, James M.

    2012-01-01

    Historically, those responsible for administration of student conduct resolution in U.S. higher education have sought some manner of moral development for students, whether labeled as such or not. It is clear that contemporary conduct officers are more deeply concerned with such student development as an extension of their practice. Many such…

  3. Student Conduct Board Manual and Reference

    ERIC Educational Resources Information Center

    ACPA College Student Educators International, 2010

    2010-01-01

    This manual is designed for those working with conduct boards composed of students and/or faculty. This manual serves two purposes: (1) To provide the Adviser and/or trainer(s) with guidelines, philosophy, and information so as to better structure your conduct board program (or to create one); and (2) To serve as an actual model for a manual for a…

  4. Mixed ionic and electronic conductivity in polymers

    SciTech Connect

    Shriver, D.F.

    1991-06-01

    New polymer films were synthesized that are mixed ionic-electronic conductors. Preliminary ion transport measurements have been made on these materials in the reduced state where electronic conductivity is negligible. We also have made preliminary measurements of switching times for these materials. Theoretical studies have been performed ion pairing in insulating and electronically conducting films.

  5. 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.

  6. Conductance Oscillations in Squashed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Mehrez, H.; Anantram, M. P.; Svizhenko, A.

    2003-01-01

    A combination of molecular dynamics and electrical conductance calculations are used to probe the electromechanical properties of squashed metallic carbon nanotubes. We find that the conductance and bandgap of armchair nanotubes show oscillations upon squashing. The physical origin of these oscillations is attributed to interaction of carbon atoms with a fourth neighbor. Squashing of armchair and zigzag nanotubes ultimately leads to metallic behavior.

  7. 75 FR 27456 - Standards of Conduct

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-17

    ...The Federal Election Commission (``Commission'' or ``FEC''), with the concurrence of the office of Government Ethics (``OGE''), seeks comments on proposed revisions to the ``Standards of Conduct,'' which are the FEC rules that govern the conduct of Commissioners and Commission employees. The proposed rules would update the Commission's current regulations to reflect statutory changes enacted......

  8. Temperament and Developmental Pathways to Conduct Problems

    ERIC Educational Resources Information Center

    Frick, Paul J.; Morris, Amanda Sheffield

    2004-01-01

    This article reviews research linking a number of temperamental vulnerabilities to the development of severe conduct problems in children. Also reviewed are 2 areas of research that focus on important developmental processes that could mediate the relation between temperament and conduct problems. These processes are the development of emotional…

  9. Conductance of Dry DNA: Role of Environment

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Adessi, Ch.; S. Walch

    2003-01-01

    This paper presents viewgraphs on the conductance of dry DNA and its effect on the surrounding environment. The topics include: 1) Approach; 2) Influence of Counter Ions; 3) Conductance Versus DNA Length; 4) Intrinsic Resonant Tunneling in Engineered DNA Sequence; and 5) Transmission Versus Energy.

  10. 75 FR 78915 - Conduct on Postal Property

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-17

    ... in 39 CFR 232.1. 1. Paragraph (f) Gambling: The prohibition of lottery ticket sales contains an... Conduct on postal property. * * * * * (f) Gambling. Participating in games for money or other personal property, the operation of gambling devices, the conduct of a lottery or pool, or the selling or...

  11. Iterative Precise Conductivity Measurement with IDEs

    PubMed Central

    Hubálek, Jaromír

    2015-01-01

    The paper presents a new approach in the field of precise electrolytic conductivity measurements with planar thin- and thick-film electrodes. This novel measuring method was developed for measurement with comb-like electrodes called interdigitated electrodes (IDEs). Correction characteristics over a wide range of specific conductivities were determined from an interface impedance characterization of the thick-film IDEs. The local maximum of the capacitive part of the interface impedance is used for corrections to get linear responses. The measuring frequency was determined at a wide range of measured conductivity. An iteration mode of measurements was suggested to precisely measure the conductivity at the right frequency in order to achieve a highly accurate response. The method takes precise conductivity measurements in concentration ranges from 10−6 to 1 M without electrode cell replacement. PMID:26007745

  12. Electrostatic control of microstructure thermal conductivity

    NASA Astrophysics Data System (ADS)

    Supino, Ryan N.; Talghader, Joseph J.

    2001-03-01

    A technology for controlling the thermal conductivity of etch-released microstructures is proposed and demonstrated by placing test structures in and out of contact with their underlying substrate. By adjusting the duty cycle of a periodic actuation, the thermal conductivity can be adjusted linearly across a wide range. Experimental work with microfilaments in air has shown a continuous tuning range from approximately 1.7×10-4 W/K to 3.3×10-4 W/K. These numbers are limited by thermal conduction through air and thermal contact conductance, respectively. The fundamental tuning range is orders of magnitude wider, limited by radiation heat transfer and the thermal contact conductance of coated structures.

  13. Low lattice thermal conductivity of stanene

    PubMed Central

    Peng, Bo; Zhang, Hao; Shao, Hezhu; Xu, Yuchen; Zhang, Xiangchao; Zhu, Heyuan

    2016-01-01

    A fundamental understanding of phonon transport in stanene is crucial to predict the thermal performance in potential stanene-based devices. By combining first-principle calculation and phonon Boltzmann transport equation, we obtain the lattice thermal conductivity of stanene. A much lower thermal conductivity (11.6 W/mK) is observed in stanene, which indicates higher thermoelectric efficiency over other 2D materials. The contributions of acoustic and optical phonons to the lattice thermal conductivity are evaluated. Detailed analysis of phase space for three-phonon processes shows that phonon scattering channels LA + LA/TA/ZA ↔ TA/ZA are restricted, leading to the dominant contributions of high-group-velocity LA phonons to the thermal conductivity. The size dependence of thermal conductivity is investigated as well for the purpose of the design of thermoelectric nanostructures. PMID:26838731

  14. The Organic Chemistry of Conducting Polymers

    SciTech Connect

    Tolbert, Laren Malcolm

    2014-12-01

    For the last several years, we have examined the fundamental principles of conduction in one-dimensional systems, i.e., molecular “wires”. It is, of course, widely recognized that such systems, as components of electronically conductive materials, function in a two- and three-dimensional milieu. Thus interchain hopping and grain-boundary resistivity are limiting conductivity factors in highly conductive materials, and overall conductivity is a function of through-chain and boundary hopping. We have given considerable attention to the basic principles underlying charge transport (the “rules of the game”) in two-dimensional systems by using model systems which allow direct observation of such processes, including the examination of tunneling and hopping as components of charge transfer. In related work, we have spent considerable effort on the chemistry of conjugated heteropolymers, most especially polythiophens, with the aim of using these most efficient of readily available electroactive polymers in photovoltaic devices.

  15. Low lattice thermal conductivity of stanene.

    PubMed

    Peng, Bo; Zhang, Hao; Shao, Hezhu; Xu, Yuchen; Zhang, Xiangchao; Zhu, Heyuan

    2016-01-01

    A fundamental understanding of phonon transport in stanene is crucial to predict the thermal performance in potential stanene-based devices. By combining first-principle calculation and phonon Boltzmann transport equation, we obtain the lattice thermal conductivity of stanene. A much lower thermal conductivity (11.6 W/mK) is observed in stanene, which indicates higher thermoelectric efficiency over other 2D materials. The contributions of acoustic and optical phonons to the lattice thermal conductivity are evaluated. Detailed analysis of phase space for three-phonon processes shows that phonon scattering channels LA + LA/TA/ZA ↔ TA/ZA are restricted, leading to the dominant contributions of high-group-velocity LA phonons to the thermal conductivity. The size dependence of thermal conductivity is investigated as well for the purpose of the design of thermoelectric nanostructures. PMID:26838731

  16. Spatial audio through a bone conduction interface.

    PubMed

    MacDonald, Justin A; Henry, Paula P; Letowski, Tomasz R

    2006-10-01

    Headphones are the standard presentation device for radio communication in the military. Although bone conduction devices possess several advantages over headphones for some military applications, they are generally considered inappropriate for inclusion in a multi-channel system. The current study tested the feasibility of a multi-channel bone conduction system by measuring the localizability of spatialized auditory stimuli presented through a pair of bone conduction vibrators. Listeners localized a Gaussian noise stimulus spatialized with individualized head-related transfer functions (HRTFs). The sounds were presented from eight virtual locations on the horizontal plane (0, +/-45, +/-90, +/-135, and 180 degrees ) through either stereo headphones or a stereo bone conduction system. Localization performance was found to be nearly identical for both audio systems, indicating that bone conduction systems can be effectively used for displaying spatial information. PMID:17062501

  17. Anisotropic thermal conductivity in uranium dioxide.

    PubMed

    Gofryk, K; Du, S; Stanek, C R; Lashley, J C; Liu, X-Y; Schulze, R K; Smith, J L; Safarik, D J; Byler, D D; McClellan, K J; Uberuaga, B P; Scott, B L; Andersson, D A

    2014-01-01

    The thermal conductivity of uranium dioxide has been studied for over half a century, as uranium dioxide is the fuel used in a majority of operating nuclear reactors and thermal conductivity controls the conversion of heat produced by fission events to electricity. Because uranium dioxide is a cubic compound and thermal conductivity is a second-rank tensor, it has always been assumed to be isotropic. We report thermal conductivity measurements on oriented uranium dioxide single crystals that show anisotropy from 4 K to above 300 K. Our results indicate that phonon-spin scattering is important for understanding the general thermal conductivity behaviour, and also explains the anisotropy by coupling to the applied temperature gradient and breaking cubic symmetry. PMID:25080878

  18. Elastic, Conductive, Polymeric Hydrogels and Sponges

    NASA Astrophysics Data System (ADS)

    Lu, Yun; He, Weina; Cao, Tai; Guo, Haitao; Zhang, Yongyi; Li, Qingwen; Shao, Ziqiang; Cui, Yulin; Zhang, Xuetong

    2014-07-01

    As a result of inherent rigidity of the conjugated macromolecular chains resulted from the delocalized π-electron system along the polymer backbone, it has been a huge challenge to make conducting polymer hydrogels elastic by far. Herein elastic and conductive polypyrrole hydrogels with only conducting polymer as the continuous phase have been simply synthesized in the indispensable conditions of 1) mixed solvent, 2) deficient oxidant, and 3) monthly secondary growth. The elastic mechanism and oxidative polymerization mechanism on the resulting PPy hydrogels have been discussed. The resulting hydrogels show some novel properties, e.g., shape memory elasticity, fast functionalization with various guest objects, and fast removal of organic infectants from aqueous solutions, all of which cannot be observed from traditional non-elastic conducting polymer counterparts. What's more, light-weight, elastic, and conductive organic sponges with excellent stress-sensing behavior have been successfully achieved via using the resulting polypyrrole hydrogels as precursors.

  19. Basic materials physics of transparent conducting oxides.

    PubMed

    Edwards, P P; Porch, A; Jones, M O; Morgan, D V; Perks, R M

    2004-10-01

    Materials displaying the remarkable combination of high electrical conductivity and optical transparency already from the basis of many important technological applications, including flat panel displays, solar energy capture and other opto-electronic devices. Here we present the basic materials physics of these important materials centred on the nature of the doping process to generate n-type conductivity in transparent conducting oxides, the associated transition to the metallic (conducting) state and the detailed properties of the degenerate itinerant electron gas. The aim is to fully understand the origins of the basic performance limits of known materials and to set the scene for new or improved materials which will breach those limits for new-generation transparent conducting materials, either oxides, or beyond oxides. PMID:15452622

  20. Thunderstorm related variations in stratospheric conductivity measurements

    NASA Technical Reports Server (NTRS)

    Hu, Hua; Holzworth, Robert H.; Li, Ya QI

    1989-01-01

    The vector electric field and polar conductivities were measured by zero-pressure balloon-borne payloads launched from Wallops Island, Virgina during the summers of 1987 and 1988. Data were collected over thunderstorms (or electrified clouds) during 6-hour flights at altitudes near 30 km. The vector electric field measurements were made with the double Langmuir probe high-impedance method, and the direct conductivity measurements were obtained with the relaxation technique. Evidence is presented for conductivity variations over thunderstorms (or electrified clouds). It is found that both positive and negative polar conductivity data do show variations of up to a factor of 2 from ambient values associated with the disturbed periods. Some ideas for possible physical mechanisms which may be responsible for the conductivity variations over thunderstorms are also discussed in this paper.

  1. Proton conducting ceramic membranes for hydrogen separation

    DOEpatents

    Elangovan, S.; Nair, Balakrishnan G.; Small, Troy; Heck, Brian

    2011-09-06

    A multi-phase proton conducting material comprising a proton-conducting ceramic phase and a stabilizing ceramic phase. Under the presence of a partial pressure gradient of hydrogen across the membrane or under the influence of an electrical potential, a membrane fabricated with this material selectively transports hydrogen ions through the proton conducting phase, which results in ultrahigh purity hydrogen permeation through the membrane. The stabilizing ceramic phase may be substantially structurally and chemically identical to at least one product of a reaction between the proton conducting phase and at least one expected gas under operating conditions of a membrane fabricated using the material. In a barium cerate-based proton conducting membrane, one stabilizing phase is ceria.

  2. Conduction at domain walls in oxide multiferroics

    SciTech Connect

    Seidel, Jan; Martin, Lane W; He, Q; Zhan, Q; Rother, A; Hawkridge, M. E.; Maksymovych, Petro; Yu, Pu; Gajek, Martin; Balke, Nina; Kalinin, Sergei V; Gemming, S; Catalan, G; Scott, J F; Spalding, Nicola A; Orenstein, J; Ramesh, R.

    2009-01-01

    Domain walls may play an important role in future electronic devices, given their small size as well as the fact that their location can be controlled. Here, we report the observation of room-temperature electronic conductivity at ferroelectric domain walls in the insulating multiferroic BiFeO{sub 3}. The origin and nature of the observed conductivity are probed using a combination of conductive atomic force microscopy, high-resolution transmission electron microscopy and first-principles density functional computations. Our analyses indicate that the conductivity correlates with structurally driven changes in both the electrostatic potential and the local electronic structure, which shows a decrease in the bandgap at the domain wall. Additionally, we demonstrate the potential for device applications of such conducting nanoscale features.

  3. Anisotropic thermal conductivity in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Gofryk, K.; Du, S.; Stanek, C. R.; Lashley, J. C.; Liu, X.-Y.; Schulze, R. K.; Smith, J. L.; Safarik, D. J.; Byler, D. D.; McClellan, K. J.; Uberuaga, B. P.; Scott, B. L.; Andersson, D. A.

    2014-08-01

    The thermal conductivity of uranium dioxide has been studied for over half a century, as uranium dioxide is the fuel used in a majority of operating nuclear reactors and thermal conductivity controls the conversion of heat produced by fission events to electricity. Because uranium dioxide is a cubic compound and thermal conductivity is a second-rank tensor, it has always been assumed to be isotropic. We report thermal conductivity measurements on oriented uranium dioxide single crystals that show anisotropy from 4 K to above 300 K. Our results indicate that phonon-spin scattering is important for understanding the general thermal conductivity behaviour, and also explains the anisotropy by coupling to the applied temperature gradient and breaking cubic symmetry.

  4. Biochemical synthesis of water soluble conducting polymers

    NASA Astrophysics Data System (ADS)

    Bruno, Ferdinando F.; Bernabei, Manuele

    2016-05-01

    An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadays tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.

  5. Elastic, Conductive, Polymeric Hydrogels and Sponges

    PubMed Central

    Lu, Yun; He, Weina; Cao, Tai; Guo, Haitao; Zhang, Yongyi; Li, Qingwen; Shao, Ziqiang; Cui, Yulin; Zhang, Xuetong

    2014-01-01

    As a result of inherent rigidity of the conjugated macromolecular chains resulted from the delocalized π-electron system along the polymer backbone, it has been a huge challenge to make conducting polymer hydrogels elastic by far. Herein elastic and conductive polypyrrole hydrogels with only conducting polymer as the continuous phase have been simply synthesized in the indispensable conditions of 1) mixed solvent, 2) deficient oxidant, and 3) monthly secondary growth. The elastic mechanism and oxidative polymerization mechanism on the resulting PPy hydrogels have been discussed. The resulting hydrogels show some novel properties, e.g., shape memory elasticity, fast functionalization with various guest objects, and fast removal of organic infectants from aqueous solutions, all of which cannot be observed from traditional non-elastic conducting polymer counterparts. What's more, light-weight, elastic, and conductive organic sponges with excellent stress-sensing behavior have been successfully achieved via using the resulting polypyrrole hydrogels as precursors. PMID:25052015

  6. An Apparent Anomaly in Peanut Leaf Conductance

    PubMed Central

    Pallas, James E.

    1980-01-01

    Conductance to gaseous transfer is normally considered to be greater from the abaxial than from the adaxial side of a leaf. Measurements of the conductance to water vapor of peanut leaves (Arachis hypogaea L.) under well watered and stress conditions in a controlled environment, however, indicated a 2-fold higher conductance from the adaxial side of the leaf than from the abaxial. Studies of conductance as light level was varied showed an increase in conductance from either surface with increasing light level, but conductance was always greater from the adaxial surface at any given light level. In contrast, measurements of soybean (Glycine max [L.] Merr.) and snapbean (Phaseolus vulgaris L.) leaf conductance showed an approximate 2-fold greater conductance from the abaxial surface than from the adaxial. Approximately the same number of stomata were present on both peanut leaf surfaces and stomatal size was similar. Electron microscopic examination of peanut leaves did not reveal any major structural differences between stomata on the two surfaces that would account for the differences in conductance. Light microscope studies of leaf sections revealed an extensive network of bundle sheaths with achloraplastic bundle sheath extensions; the lower epidermis was lined with a single layer of large achloraplastic parenchyma cells. Measurements of net photosynthesis made on upper and lower leaf surfaces collectively and individually indicated that two-thirds of the peanut leaf's total net photosynthesis can be attributed to diffusion of CO2 through the adaxial leaf surface. Possibly the high photosynthetic efficiency of peanut cultivars as compared with certain other C3 species is associated with the greater conductance of CO2 through their upper leaf surfaces. Images PMID:16661294

  7. Complex conductivity of organic-rich shales

    NASA Astrophysics Data System (ADS)

    Woodruff, W. F.; Revil, A.; Torres-Verdin, C.

    2013-12-01

    We can accurately determine the intrinsic anisotropy and material properties in the laboratory, providing empirical evidence of transverse isotropy and the polarization of the organic and metallic fractions in saturated and unsaturated shales. We develop two distinct approaches to obtain the complex conductivity tensor from spectral induced polarization (SIP) measurements. Experimental results indicate clear anisotropy, and characterize the effects of thermal maturation, TOC, and pyrite, aiding in the calibration and interpretation of geophysical data. SIP is a non-intrusive measurement, sensitive to the surface conductance of mineral grains, frequency-dependent polarization of the electrical double layer, and bulk conductivity of the pore water. The in-phase and quadrature components depend upon parameters of principal importance in unconventional shale formation evaluation (e.g., the distribution of pore throat sizes, formation factor, permeability, salinity and cation exchange capacity (CEC), fluid saturation and wettability). In addition to the contribution of the electrical double layer of non-conducting minerals to surface conductivity, we have observed a clear relaxation associated with kerogen pyrolysis, pyrite distribution, and evidence that the CEC of the kerogen fraction may also contribute, depending on thermal maturation history. We utilize a recent model for anisotropic complex conductivity, and rigorous experimental protocols to quantify the role of kerogen and pyrolysis on surface and quadrature conductivity in mudrocks. The complex conductivity tensor σ* describes the directional dependence of electrical conduction in a porous medium, and accounts for both conduction and polarization. The complex-valued tensor components are given as σ*ij , where σ'ij represents in-phase and σ"ij denotes quadrature conductivities. The directional dependence of the complex conductivity tensor is relegated to the textural properties of the material. The

  8. Thermal conductivity of garnet laser crystals

    NASA Astrophysics Data System (ADS)

    Wang, B. S.; Jiang, H. H.; Zhang, Q. L.; Yin, S. T.

    2008-03-01

    The thermal conductivities of nine different synthetic garnet laser crystals at various temperatures, range from 273 to 393 K have been investigated by instantaneous measurement method. The results show that the thermal conductivity of each crystal decreases exponentially with the temperature increasing. It is notable that, different host crystals, such as YAG, GGG, and GSGG have different thermal conductivity, which is attributed to the crucial influence of crystal structure and composition on the absolute value of their thermal conductivity. Moreover, with respect to the same host crystals, the impurity scattering also results in the change of their thermal conductivities. This is because that a higher concentration of doped ions leads to a more phonon scattering modes, which results in a shorter mean free path of the phonons and a lower thermal conductivity. In addition, different host crystals have various dependences of thermal conductivity on dopant concentration. This works provides reliable and useful information for designing high power, high quality, and high stability laser devices.

  9. Thermal conductivity of synthetic garnet laser crystals

    NASA Astrophysics Data System (ADS)

    Wang, B. S.; Jiang, H. H.; Zhang, Q. L.; Yin, S. T.

    2007-07-01

    The thermal conductivities of nine different synthetic garnet laser crystals at various temperatures, range from 273 to 393K have been investigated by instantaneous measurement method. The results show that the thermal conductivity of each crystal decreases exponentially with the temperature increasing. It is notable that, different host crystals, such as YAG, GGG, and GSGG have different thermal conductivity, which is attributed to the crucial influence of crystal structure and composition on the absolute value of their thermal conductivity. Moreover, with respect to the same host crystals, the impurity scattering also results in the change of their thermal conductivities. This is because that a higher concentration of doped ions leads to a more phonon scattering modes, which results in a shorter mean free path of the phonons and a lower thermal conductivity. In addition, different host crystals have various dependences of thermal conductivity on dopant concentration. This works provides reliable and useful information for designing high power, high quality, and high stability laser devices.

  10. Optical sheet conductivities of layered oxides

    NASA Astrophysics Data System (ADS)

    Tanabe, Kenji; Taniguchi, Hiroki; Terasaki, Ichiro

    2016-08-01

    We report on the optical properties of the layered Co oxides Bi2‑x Pb x Sr2Co2O8 with x  =  0 and 0.4 and discuss similarities among optical sheet conductivities of layered Co and Cu oxides. Optical sheet conductivity is defined as the product of the optical conductivity and the lattice parameter along the cross-layer direction. Although the optical conductivity spectra of both Bi2‑x Pb x Sr2Co2O8 with x  =  0 and 0.4 are similar in shape to Na0.75CoO2 and Ca3Co4O9 below 3 eV, they are much smaller in magnitude. In contrast, optical sheet conductivities are roughly identical among the four Co oxides below 3 eV, which indicates that the common CoO2 layer in these oxides has the same electronic state. In addition, we find that optical sheet conductivities are identical among the layered Cu oxides with a four-fold coordinated CuO4 plane. We suggest using optical sheet conductivity as a key concept to discuss the similarity among the layered materials.

  11. Thermal conductivity of uterine tissue in vitro.

    PubMed

    Olsrud, J; Friberg, B; Ahlgren, M; Persson, B R

    1998-08-01

    Thermotherapy of the uterus has emerged as an alternative to hysterectomy in the treatment of menorrhagia, from whence it follows that the thermal properties of uterine tissue have become of importance. This study presents measurements of the thermal conductivity and the water content of uterine tissue in vitro. A steady-state thermal conductivity apparatus, based on the comparison of test samples with a material with known thermal conductivity, is described. Measurements were conducted on tissue samples from eleven patients, directly after hysterectomy. Samples with and without endometrium, as well as coagulated samples, were examined. The thermal conductivity of myometrial tissue was found to be 0.536 +/- 0.012 W m(-1) K(-1) (mean +/- 1 SD) and the corresponding water content was 81.2 +/- 1.5% (mean +/- 1 SD). Measurements on samples with both endometrium and myometrium showed similar thermal conductivity (0.542 +/- 0.008 W m(-1) K(-1), mean +/- 1 SD) and water content (81.6 +/- 0.7%, mean +/- 1 SD). It was also indicated that coagulation causes dehydration, resulting in a lower thermal conductivity. PMID:9725614

  12. Thermal conductivity measurements of Summit polycrystalline silicon.

    SciTech Connect

    Clemens, Rebecca; Kuppers, Jaron D.; Phinney, Leslie Mary

    2006-11-01

    A capability for measuring the thermal conductivity of microelectromechanical systems (MEMS) materials using a steady state resistance technique was developed and used to measure the thermal conductivities of SUMMiT{trademark} V layers. Thermal conductivities were measured over two temperature ranges: 100K to 350K and 293K to 575K in order to generate two data sets. The steady state resistance technique uses surface micromachined bridge structures fabricated using the standard SUMMiT fabrication process. Electrical resistance and resistivity data are reported for poly1-poly2 laminate, poly2, poly3, and poly4 polysilicon structural layers in the SUMMiT process from 83K to 575K. Thermal conductivity measurements for these polysilicon layers demonstrate for the first time that the thermal conductivity is a function of the particular SUMMiT layer. Also, the poly2 layer has a different variation in thermal conductivity as the temperature is decreased than the poly1-poly2 laminate, poly3, and poly4 layers. As the temperature increases above room temperature, the difference in thermal conductivity between the layers decreases.

  13. Optical sheet conductivities of layered oxides.

    PubMed

    Tanabe, Kenji; Taniguchi, Hiroki; Terasaki, Ichiro

    2016-08-17

    We report on the optical properties of the layered Co oxides Bi2-x Pb x Sr2Co2O8 with x  =  0 and 0.4 and discuss similarities among optical sheet conductivities of layered Co and Cu oxides. Optical sheet conductivity is defined as the product of the optical conductivity and the lattice parameter along the cross-layer direction. Although the optical conductivity spectra of both Bi2-x Pb x Sr2Co2O8 with x  =  0 and 0.4 are similar in shape to Na0.75CoO2 and Ca3Co4O9 below 3 eV, they are much smaller in magnitude. In contrast, optical sheet conductivities are roughly identical among the four Co oxides below 3 eV, which indicates that the common CoO2 layer in these oxides has the same electronic state. In addition, we find that optical sheet conductivities are identical among the layered Cu oxides with a four-fold coordinated CuO4 plane. We suggest using optical sheet conductivity as a key concept to discuss the similarity among the layered materials. PMID:27321944

  14. Conductance measurement circuit with wide dynamic range

    NASA Technical Reports Server (NTRS)

    Mount, Bruce E. (Inventor); Von Esch, Myron (Inventor)

    1994-01-01

    A conductance measurement circuit to measure conductance of a solution under test with an output voltage proportional to conductance over a 5-decade range, i.e., 0.01 uS to 1000 uS or from 0.1 uS to 10,000 uS. An increase in conductance indicates growth, or multiplication, of the bacteria in the test solution. Two circuits are used each for an alternate half-cycle time periods of an alternate squarewave in order to cause alternate and opposite currents to be applied to the test solution. The output of one of the two circuits may be scaled for a different range optimum switching frequency dependent upon the solution conductance and to enable uninterrupted measurement over the complete 5-decade range. This circuitry provides two overlapping ranges of conductance which can be read simultaneously without discontinuity thereby eliminating range switching within the basic circuitry. A VCO is used to automatically change the operating frequency according to the particular value of the conductance being measured, and comparators indicate which range is valid and also facilitate computer-controlled data acquisition. A multiplexer may be used to monitor any number of solutions under test continuously.

  15. Proton Conductivity Studies on Biopolymer Electrolytes

    SciTech Connect

    Harun, N. I.; Sabri, N. S.; Rosli, N. H. A.; Taib, M. F. M.; Saaid, S. I. Y.; Kudin, T. I. T.; Ali, A. M. M.; Yahya, M. Z. A.

    2010-07-07

    Proton conducting solid biopolymer electrolyte membranes consisting of methyl cellulose (MC) and different wt.% of ammonium nitrate (NH{sub 4}NO{sub 3}) were prepared by solution cast technique. Impedance spectroscopy was carried out to study electrical characteristics of bulk materials. The ionic conductivity of the prepared samples was calculated using the bulk resistance (R{sub b}) obtained from impedance spectroscopy plot. The highest ionic conductivity obtained was 1.17x10{sup -4} Scm{sup -1} for the sample with composition ratio of MC(50): NH{sub 4}NO{sub 3}(50). To enhance the ionic conductivity, propylene carbonate (PC) and ethylene carbonate (EC) plasticizers were introduced. It was found that the ionic conductivity of polymer electrolyte membranes increased with the increase in plasticizers concentration. The ionic conductivities of solid polymer electrolytes based on MC-NH{sub 4}NO{sub 3}-PC was enhanced up to 4.91x10{sup -3} Scm{sup -1} while for the MC-NH{sub 4}NO{sub 3}-EC system, the highest conductivity was 1.74x10{sup -2} Scm{sup -1}. The addition of more plasticizer however decreases in mechanical stability of the membranes.

  16. The Electronic Thermal Conductivity of Graphene.

    PubMed

    Kim, Tae Yun; Park, Cheol-Hwan; Marzari, Nicola

    2016-04-13

    Graphene, as a semimetal with the largest known thermal conductivity, is an ideal system to study the interplay between electronic and lattice contributions to thermal transport. While the total electrical and thermal conductivity have been extensively investigated, a detailed first-principles study of its electronic thermal conductivity is still missing. Here, we first characterize the electron-phonon intrinsic contribution to the electronic thermal resistivity of graphene as a function of doping using electronic and phonon dispersions and electron-phonon couplings calculated from first-principles at the level of density-functional theory and many-body perturbation theory (GW). Then, we include extrinsic electron-impurity scattering using low-temperature experimental estimates. Under these conditions, we find that the in-plane electronic thermal conductivity κe of doped graphene is ∼300 W/mK at room temperature, independently of doping. This result is much larger than expected and comparable to the total thermal conductivity of typical metals, contributing ∼10% to the total thermal conductivity of bulk graphene. Notably, in samples whose physical or domain sizes are of the order of few micrometers or smaller, the relative contribution coming from the electronic thermal conductivity is more important than in the bulk limit, because lattice thermal conductivity is much more sensitive to sample or grain size at these scales. Last, when electron-impurity scattering effects are included we find that the electronic thermal conductivity is reduced by 30 to 70%. We also find that the Wiedemann-Franz law is broadly satisfied at low and high temperatures but with the largest deviations of 20-50% around room temperature. PMID:26907524

  17. The electrical conductivity of eclogite in Tibet

    NASA Astrophysics Data System (ADS)

    Guo, Y.; Wang, D.

    2011-12-01

    Qinghai-Tibet Plateau is known as its huge crust and complicated plateau plate tectonics. To understand the geodynamics of this plateau, a variety of geology surveys and geophysical observations were carried out. MT results reveal that the high conductivity zones widely present both in the crust and the mantle. These conductivity anomalies were interpreted as the presence of melt by many researchers. The eclogite is considered as one of candidate rock constituting the lower crust and uppermost mantle. Thus, the electrical conductivity eclogite may provide available information to understand the electrical structure of the crust and the mantle beneath Tibet. The starting material is natural eclogite collected from Pianshishan area, which is located in the middle of Qiangtang. The electrical conductivity of eclogite was measured by using the impedance spectrum method at 1.5, 2.5, 3.5 GPa and 372 ~ 803 K. Oxygen fugacity was controlled by the Mo-MoO2 buffer, The sample temperatures were monitored by a NiCr-NiAl thermocouple. The results show that the pressure weakly affect the electrical conductivity of eclogite. The electrical conductivity of eclogite varies from -5.5 S / m to -1.75 S / m with the temperature increased. The electrical conductivity curves change the slope and alter the conduction mechanism at various pressures. The low-temperature activation enthalpy at 1.5, 2.5, 3.5 GP are 0.380, 0.405, 0.446 eV, whereas high-temperature activation enthalpy are 0.986, 0.986, 1.023 eV, respectively. This results were entrapped to Earth's interior and compared with the magnetotelluric(MT) observations, our model is consistent with one of the electrical conductivity structures derived from geophysical observations.

  18. 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.

  19. Conductance Studies on Aqueous Citric Acid

    NASA Astrophysics Data System (ADS)

    Apelblat, Alexander; Barthel, Josef

    1991-02-01

    Conductance measurements of citric acid and neutral citrates (tri-lithium citrate, tri-sodium citrate and tri-potassium citrate) were performed in water at 278.15 to 308.15 K. The equilibrium constants for the primary and secondary steps of dissociation, Kx and K2, and the limiting conductances, λ0(H2Cit-), λ°(1/2 HCit2-), and λ0(1/3 Cit3-) are reported as a function of temperature. They are obtained by application of the Quint and Viallard conductance equation. The enthalpies of dissociation are estimated.

  20. Prediction of rigid silica based insulation conductivity

    NASA Technical Reports Server (NTRS)

    Williams, Stanley D.; Curry, Donald M.

    1993-01-01

    A method is presented for predicting the thermal conductivity of low density, silica based fibrous insulators. It is shown that the method can be used to extend data values to the upper material temperature limits from those obtained from the test data. It is demonstrated that once the conductivity is accurately determined by the analytical model the conductivity for other atmospheres can be predicted. The method is similar to that presented by previous investigators, but differs significantly in the contribution due to gas and internal radiation.

  1. Thermal Conductivity Of Natural Type IIa Diamond

    NASA Technical Reports Server (NTRS)

    Vandersande, Jan; Vining, Cronin; Zoltan, Andrew

    1992-01-01

    Report describes application of flash diffusivity method to measure thermal conductivity of 8.04 x 8.84 x 2.35-mm specimen of natural, white, type-IIa diamond at temperatures between 500 and 1,250 K. Provides baseline for comparison to isotopically pure (12C) diamond. Results used as reference against which diamond films produced by chemical-vapor deposition at low pressures can be compared. High thermal conductivity of diamond exploited for wide variety of applications, and present results also used to estimate heat-conduction performances of diamond films in high-temperature applications.

  2. Adjustable thermal conductivity in carbon nanotube nanofluids

    NASA Astrophysics Data System (ADS)

    Xie, Huaqing; Chen, Lifei

    2009-05-01

    Homogeneous and stable nanofluids have been produced by suspending well dispersible multi-walled carbon nanotubes (CNTs) into ethylene glycol base fluid. CNT nanofluids have enhanced thermal conductivity and the enhancement ratios increase with the nanotube loading and the temperature. Thermal conductivity enhancement was adjusted by ball milling and cutting the treated CNTs suspended in the nanofluids to relatively straight CNTs with an appropriate length distribution. Our findings indicate that the straightness ratio, aspect ratio, and aggregation have collective influence on the thermal conductivity of CNT nanofluids.

  3. Thermal conductivity behavior of boron carbides

    NASA Technical Reports Server (NTRS)

    Wood, C.; Zoltan, A.; Emin, D.; Gray, P. E.

    1983-01-01

    Knowledge of the thermal conductivity of boron carbides is necessary to evaluate its potential for high temperature thermoelectric energy conversion applications. The thermal diffusivity of hot pressed boron carbide B/sub 1-x/C/sub x/ samples as a function of composition, temperature and temperature cycling was measured. These data in concert with density and specific heat data yield the thermal conductivities of these materials. The results in terms of a structural model to explain the electrical transport data and novel mechanisms for thermal conduction are discussed.

  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. Electronically conducting polymers with silver grains

    NASA Technical Reports Server (NTRS)

    Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor); Hodko, Dolibor (Inventor)

    1999-01-01

    The present invention provides electronically conducting polymer films formed from photosensitive formulations of pyrrole and an electron acceptor that have been selectively exposed to UV light, laser light, or electron beams. The formulations may include photoinitiators, flexibilizers, solvents and the like. These solutions can be used in applications including printed circuit boards and through-hole plating and enable direct metallization processes on non-conducting substrates. After forming the conductive polymer patterns, a printed wiring board can be formed by sensitizing the polymer with palladium and electrolytically depositing copper.

  6. Increased thermal conductivity monolithic zeolite structures

    DOEpatents

    Klett, James; Klett, Lynn; Kaufman, Jonathan

    2008-11-25

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  7. Poole-Frenkel conduction in polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Gonon, P.; Boiko, Y.; Prawer, S.; Jamieson, D.

    1996-04-01

    High-field electrical conduction has been studied in undoped polycrystalline diamond over a wide temperature range. The current increases exponentially with the electric field with an exponential factor which increases linearly with the inverse of temperature. The activation energy of the conductivity is found to be strongly field dependent and to decrease linearly with the electric field. The experimental data support a Poole-Frenkel conduction with overlapping centers. The centers are found to be located at around 1.1 eV from the band edge with a density of about 2×1017 cm-3.

  8. Thermal conductivity of bulk nanostructured lead telluride

    SciTech Connect

    Hori, Takuma; Chen, Gang; Shiomi, Junichiro

    2014-01-13

    Thermal conductivity of lead telluride with embedded nanoinclusions was studied using Monte Carlo simulations with intrinsic phonon transport properties obtained from first-principles-based lattice dynamics. The nanoinclusion/matrix interfaces were set to completely reflect phonons to model the maximum interface-phonon-scattering scenario. The simulations with the geometrical cross section and volume fraction of the nanoinclusions matched to those of the experiment show that the experiment has already reached the theoretical limit of thermal conductivity. The frequency-dependent analysis further identifies that the thermal conductivity reduction is dominantly attributed to scattering of low frequency phonons and demonstrates mutual adaptability of nanostructuring and local disordering.

  9. Conduction mechanism of single-crystal alumina

    NASA Technical Reports Server (NTRS)

    Will, Fritz G.; Delorenzi, Horst G.; Janora, Kevin H.

    1992-01-01

    The fully guarded three-terminal technique was used to perform conductivity measurements on single-crystal alumina at temperatures of 400-1300 C. The conductivity was also determined as a function of time at various temperatures and applied fields. Further, the fractions of the current carried by Al and O ions (ionic transference numbers) were determined from long-term transference experiments in the temperature range 1100-1300 C. A mathematical model of the conduction mechanism is proposed, and model predictions are compared with experimental results.

  10. Conductive Tether Coating for Electrodynamic Tethers

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.; Schuler, Pete

    2000-01-01

    The Propulsive Small Expendable Deployer System (ProSEDS), which is an on-orbit demonstration of the propulsion capabilities of electrodynamic tethers in space, is a secondary payload on a Delta 11 unmanned expendable booster. The ProSEDS tether consists of a 5 km bare electrodynamic tether and a 1 0-km non-conductive leader tether. Near the Delta 11, 160 m of the conductive tether is insulated to prevent plasma electron collection from the plasma contactor and for other science requirements. The remainder of the 5-km conductive tether is coated with a new conductive coating to collect plasma electrons. A bare metal tether easily collects electrons from the plasma, but thermal concerns preclude this design. A highly emissive conductive polymer developed by Triton Systems, Inc. has been optimized for both conductivity and thermo-optical properties. The current design for the ProSEDS conductive tether is seven individually coated strands of 28 AWG aluminum wire, coated with an atomic oxygen-resistant conductive polymer composed of a mixture of COR (Colorless Oxygen Resistant) and polyanaline (PANI) known as C-COR (Conductive-Colorless Oxygen Resistant). The conductive-coated wire strands are cold-welded to individually coated strands of the insulated tether. The insulated tether is coated with 1 mil of polyimide and an atomic oxygen resistant polymer TOR-BP. The insulated tether must stand off the entire voltage of the tether (1 200 V) at various times during the mission. All seven wires are twisted around a Kevlar-29 core using the Hi-wire design. Extensive testing has been performed at the Marshall Space Flight Center to qualify both the conductive coating and insulating coating for use on the ProSEDS tether. The conductive coating has been exposed to a plasma to verify the coatings ability to collect electrons from the space plasma from 0 to 1500 V, and to verify the coatings ability to collect electrons after atomic oxygen exposure. The insulated coating has been

  11. Measurement of the thermal contact conductance and thermal conductivity of anodized aluminum coatings

    SciTech Connect

    Peterson, G.P.; Fletcher, L.S. )

    1990-08-01

    An experimental investigation was conducted to determine the thermal contact conductance and effective thermal conductivity of anodized coatings. One chemically polished Aluminum 6061-T6 test specimen and seven specimens with anodized coatings varying in thickness from 60.9 {mu}m to 163.8 {mu}m were tested while in contact with a single unanodized aluminum surface. Measurements of the overall joint conductance, composed of the thermal contact conductance between the anodized coating and the bare aluminum surface and the bulk conductance of the coating material, indicated that the overall joint conductance decreased with increasing thickness of the anodized coating and increased with increasing interfacial load. Using the experimental data, a dimensionless expression was developed that related the overall joint conductance to the coating thickness, the surface roughness, the interfacial pressure, and the properties of the aluminum substrate. By subtracting the thermal contact conductance from the measured overall joint conductance, estimations of the effective thermal conductivity of the anodized coating as a function of pressure were obtained for each of the seven anodized specimens. At an extrapolated pressure of zero, the effective thermal conductivity was found to be approximately 0.02 W/m-K. In addition to this extrapolated value, a single expression for predicting the effective thermal conductivity as a function of both the interface pressure and the anodized coating thickness was developed and shown to be within {plus minus}5 percent of the experimental data over a pressure range of 0 to 14 MPa.

  12. Domain wall conduction in multiaxial ferroelectrics

    SciTech Connect

    Eliseev, E. A.; Morozovska, A. N.; Svechnikov, S. V.; Maksymovych, Petro; Kalinin, Sergei V

    2012-01-01

    The conductance of domain wall structures consisting of either stripes or cylindrical domains in multiaxial ferroelectric-semiconductors is analyzed. The effects of the flexoelectric coupling, domain size, wall tilt, and curvature on charge accumulation are analyzed using the Landau-Ginsburg Devonshire theory for polarization vector combined with the Poisson equation for charge distributions. The proximity and size effect of the electron and donor accumulation/depletion by thin stripe domains and cylindrical nanodomains are revealed. In contrast to thick domain stripes and wider cylindrical domains, in which the carrier accumulation (and so the static conductivity) sharply increases at the domain walls only, small nanodomains of radii less than 5-10 correlation lengths appeared conducting across the entire cross-section. Implications of such conductive nanosized channels may be promising for nanoelectronics.

  13. First-principles transversal DNA conductance deconstructed

    SciTech Connect

    Zhang, Xiaoguang; Krstic, Predrag; Zikic, Radomir; Wells, Jack C; Fuentes-Cabrera, Miguel A

    2006-01-01

    First-principles calculation of the transverse conductance across DNA fragments placed between gold nanoelectrodes, reveals that such conductance describes electron tunneling that depends critically on geometrical rather than electronic-structure properties. By factoring the first-principles result into two simple and approximately independent tunneling factors, we show that the conductances of the A, C, G, and T fragments differ only because of their sizes: the larger is the DNA base, the smaller is the distance that separates the electrode from the corresponding molecule, and the larger is its conductance. Because the geometrical factors are difficult to control in an experiment, the DC-current measurements across DNA may not be a convenient approach to DNA sequencing.

  14. Unusual Conductance in Cumulene Molecular Wires

    NASA Astrophysics Data System (ADS)

    Prasongkit, Jariyanee; Grigoriev, Anton; Wendin, Göran; Ahuja, Rajeev

    2009-03-01

    We report current-voltage curves and conductance of cumulene molecular wire suspended between Au(111) surfaces via thiolate bonds with full self-consistent ab initio calculation under external bias. The conductance of cumulene wires shows oscillatory behavior depending on the number of carbon atoms. Among all conjugated oligomers, we find that odd-number cumulene wires yield the highest conductance and present ballistic-like transport behavior. The reason has been traced to two factors: high density of state at the Fermi level, and the alignment of molecular orbital closed to Fermi level. Since the conductance depends weakly on applied bias, and the current voltage characteristic is linear under bias region -0.9 to 0.9 V, odd-number cumulene wire is a possible candidate as a near- perfect, ballistic one-dimensional molecular wire.

  15. Hydrodynamic Model for Conductivity in Graphene

    PubMed Central

    Mendoza, M.; Herrmann, H. J.; Succi, S.

    2013-01-01

    Based on the recently developed picture of an electronic ideal relativistic fluid at the Dirac point, we present an analytical model for the conductivity in graphene that is able to describe the linear dependence on the carrier density and the existence of a minimum conductivity. The model treats impurities as submerged rigid obstacles, forming a disordered medium through which graphene electrons flow, in close analogy with classical fluid dynamics. To describe the minimum conductivity, we take into account the additional carrier density induced by the impurities in the sample. The model, which predicts the conductivity as a function of the impurity fraction of the sample, is supported by extensive simulations for different values of ε, the dimensionless strength of the electric field, and provides excellent agreement with experimental data. PMID:23316277

  16. Information filtering via biased heat conduction.

    PubMed

    Liu, Jian-Guo; Zhou, Tao; Guo, Qiang

    2011-09-01

    The process of heat conduction has recently found application in personalized recommendation [Zhou et al., Proc. Natl. Acad. Sci. USA 107, 4511 (2010)], which is of high diversity but low accuracy. By decreasing the temperatures of small-degree objects, we present an improved algorithm, called biased heat conduction, which could simultaneously enhance the accuracy and diversity. Extensive experimental analyses demonstrate that the accuracy on MovieLens, Netflix, and Delicious datasets could be improved by 43.5%, 55.4% and 19.2%, respectively, compared with the standard heat conduction algorithm and also the diversity is increased or approximately unchanged. Further statistical analyses suggest that the present algorithm could simultaneously identify users' mainstream and special tastes, resulting in better performance than the standard heat conduction algorithm. This work provides a creditable way for highly efficient information filtering. PMID:22060533

  17. Information filtering via biased heat conduction

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Guo; Zhou, Tao; Guo, Qiang

    2011-09-01

    The process of heat conduction has recently found application in personalized recommendation [Zhou , Proc. Natl. Acad. Sci. USA PNASA60027-842410.1073/pnas.1000488107107, 4511 (2010)], which is of high diversity but low accuracy. By decreasing the temperatures of small-degree objects, we present an improved algorithm, called biased heat conduction, which could simultaneously enhance the accuracy and diversity. Extensive experimental analyses demonstrate that the accuracy on MovieLens, Netflix, and Delicious datasets could be improved by 43.5%, 55.4% and 19.2%, respectively, compared with the standard heat conduction algorithm and also the diversity is increased or approximately unchanged. Further statistical analyses suggest that the present algorithm could simultaneously identify users' mainstream and special tastes, resulting in better performance than the standard heat conduction algorithm. This work provides a creditable way for highly efficient information filtering.

  18. Blue Origin Conducts Pad Escape Test

    NASA Video Gallery

    Blue Origin conducted a successful pad escape test Oct. 19 at the company's West Texas launch site, firing its pusher escape motor and launching a full-scale suborbital crew capsule from a simulate...

  19. Surface conductivity in rocks: a review

    NASA Astrophysics Data System (ADS)

    Ruffet, C.; Darot, M.; Guéguen, Y.

    1995-01-01

    Electrical properties of rocks depend on composition (i.e. bulk properties of the constituents), micro structure (i.e. geometrical arrangement of the constituents) and interfacial effects. We consider here a rock as a three component system — grains, pores, and interfaces — in order to account for the observed behaviour. We review first the main results relative to DC. conductivity. Surface conductivity effects show up clearly in the case of shaly formations or at low salinities. Although Archies' law (1942) and Waxman and Smits model (1968) are widely used, a more physically based model is that of Johnson and Sen (1988). We review also the variable frequency conductivity (complex conductivity) data and models. The important effect in that case is the enhancement of the dielectric constant at low frequencies (Knight and Nur, 1987) which can be interpreted as a geometrical effect although electrochemical interactions may also play an important role at low frequencies, depending on the rock type.

  20. Heat conduction fronts in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Soker, Noam

    1994-01-01

    We present arguments which suggest that many of the x-ray, some optical, and some UV observations of planetary nebulae, can be explained by the presence of heat conduction fronts. The heat flows from the hot bubble formed by the shocked fast wind to the cool shell and halo. Heat conduction fronts are likely to account for emission of x rays from plasma at lower temperature than the expected temperature of the hot bubble. In the presence of magnetic fields, only a small fraction of the fast wind luminosity emerges as radiation. Heat conduction fronts can naturally produce some unusual line flux ratios, which are observed in some planetary nebulae. Heat conduction fronts may heat the halo and cause some material at the inner surface of the shell to expand slower than the rest of the shell. In the presence of an asymmetrical magnetic field, this flow, the x-ray intensity, and the emission lines, may acquire asymmetrical structure as well.

  1. A Robust Approach to Lattice Thermal Conductivity

    NASA Astrophysics Data System (ADS)

    Nielson, Weston; Fei Zhou Team; Yi Xia Team; Vidvuds Ozolins Team

    2015-03-01

    Thermal conductivity is a key parameter in designing high performance thermoelectric materials. A multitude of computational methods have been developed to calculate lattice thermal conductivity. Molecular dynamics (MD) based techniques, including equilibrium and non-equilibrium methods, in addition to non MD-based solutions, such as the Boltzmann Transport Equation (BTE), are all capable of calculating thermal conductivity, but each comes with different sets of limitations and difficulties. After extensive use of these different methods, we have developed a robust set of tools for obtaining high-quality lattice thermal conductivity values of crystalline solids. The crux of our method involves a novel compressive sensing (CS) based approach for efficiently calculating high quality force constants for crystalline materials. The result is a technique for building lattice dynamical models that can treat compounds with large, complex unit cells and strong anharmonicity, including those with harmonically unstable phonon modes.

  2. Composite Solid Electrolyte Containing Li+- Conducting Fibers

    NASA Technical Reports Server (NTRS)

    Appleby, A. John; Wang, Chunsheng; Zhang, Xiangwu

    2006-01-01

    Improved composite solid polymer electrolytes (CSPEs) are being developed for use in lithium-ion power cells. The matrix components of these composites, like those of some prior CSPEs, are high-molecular-weight dielectric polymers [generally based on polyethylene oxide (PEO)]. The filler components of these composites are continuous, highly-Li(+)-conductive, inorganic fibers. PEO-based polymers alone would be suitable for use as solid electrolytes, were it not for the fact that their room-temperature Li(+)-ion conductivities lie in the range between 10(exp -6) and 10(exp -8) S/cm, too low for practical applications. In a prior approach to formulating a CSPE, one utilizes nonconductive nanoscale inorganic filler particles to increase the interfacial stability of the conductive phase. The filler particles also trap some electrolyte impurities. The achievable increase in conductivity is limited by the nonconductive nature of the filler particles.

  3. Lattice thermal conductivity crossovers in semiconductor nanowires.

    PubMed

    Mingo, N; Broido, D A

    2004-12-10

    For binary compound semiconductor nanowires, we find a striking relationship between the nanowire's thermal conductivity kappa(nwire), the bulk material's thermal conductivity kappa(bulk), and the mass ratio of the material's constituent atoms, r, as kappa(bulk)/kappa(nwire) (alpha) (1+1/r)(-3/2). A significant consequence is the presence of crossovers in which a material with higher bulk thermal conductivity than the rest is no longer the best nanowire thermal conductor. We show that this behavior stems from a change in the dominant phonon scattering mechanism with decreasing nanowire size. The results have important implications for nanoscale heat dissipation, thermoelectricity, and thermal conductivity of nanocomposites. PMID:15697834

  4. GUIDE FOR CONDUCTING TREATABILITY STUDIES UNDER CERCLA

    EPA Science Inventory

    Systematically conducted, well-documented treatability studies are an important component of the removal process, remedial investigation/ feasibility study (RI/FS) process and the remedial design/remedial action (RD/RA) process under the Comprehensive Environmental Response...

  5. Thermal Conductances of Pressed Copper Contacts

    NASA Technical Reports Server (NTRS)

    Salerno, L.; Kittel, P.; Spivak, A.

    1986-01-01

    Report describes investigation of thermal conductivities of smooth copper contacts pressed together at liquid-helium temperatures. Investigation prompted by need for accurate thermal models for infrared detectors and other cryogenic instruments.

  6. Conductivity Probe after Trench-Bottom Placement

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Needles of the thermal and conductivity probe on NASA's Phoenix Mars Lander were positioned into the bottom of a trench called 'Upper Cupboard' during Sol 86 (Aug. 21, 2008), or 86th Martian day after landing. This image of the conductivity probe after it was raised back out of the trench was taken by Phoenix's Robotic Arm Camera. The conductivity probe is at the wrist of the robotic arm's scoop.

    The probe measures how fast heat and electricity move from one needle to an adjacent one through the soil or air between the needles. Conductivity readings can be indicators about water vapor, water ice and liquid water.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  7. 39 CFR 447.21 - Prohibited conduct.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... for an examination of the Office of Personnel Management or Board of Examiners for the Foreign Service... lottery or pool, in conducting a game for money or property, or in selling or purchasing a numbers slip...

  8. 39 CFR 447.21 - Prohibited conduct.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... for an examination of the Office of Personnel Management or Board of Examiners for the Foreign Service... lottery or pool, in conducting a game for money or property, or in selling or purchasing a numbers slip...

  9. 39 CFR 447.21 - Prohibited conduct.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... for an examination of the Office of Personnel Management or Board of Examiners for the Foreign Service... lottery or pool, in conducting a game for money or property, or in selling or purchasing a numbers slip...

  10. 39 CFR 447.21 - Prohibited conduct.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... for an examination of the Office of Personnel Management or Board of Examiners for the Foreign Service... lottery or pool, in conducting a game for money or property, or in selling or purchasing a numbers slip...

  11. Thermal Conductivity in Nanocrystalline Ceria Thin Films

    SciTech Connect

    Marat Khafizov; In-Wook Park; Aleksandr Chernatynskiy; Lingfeng He; Jianliang Lin; John J. Moore; David Swank; Thomas Lillo; Simon R. Phillpot; Anter El-Azab; David H. Hurley

    2014-02-01

    The thermal conductivity of nanocrystalline ceria films grown by unbalanced magnetron sputtering is determined as a function of temperature using laser-based modulated thermoreflectance. The films exhibit significantly reduced conductivity compared with stoichiometric bulk CeO2. A variety of microstructure imaging techniques including X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron analysis, and electron energy loss spectroscopy indicate that the thermal conductivity is influenced by grain boundaries, dislocations, and oxygen vacancies. The temperature dependence of the thermal conductivity is analyzed using an analytical solution of the Boltzmann transport equation. The conclusion of this study is that oxygen vacancies pose a smaller impediment to thermal transport when they segregate along grain boundaries.

  12. Mixed Conducting Electrodes for Better AMTEC Cells

    NASA Technical Reports Server (NTRS)

    Ryan, Margaret; Williams, Roger; Homer, Margie; Lara. Liana

    2003-01-01

    Electrode materials that exhibit mixed conductivity (that is, both electronic and ionic conductivity) have been investigated in a continuing effort to improve the performance of the alkali metal thermal-to-electric converter (AMTEC). These electrode materials are intended primarily for use on the cathode side of the sodium-ion-conducting solid electrolyte of a sodium-based AMTEC cell. They may also prove useful in sodium-sulfur batteries, which are under study for use in electric vehicles. An understanding of the roles played by the two types of conduction in the cathode of a sodium-based AMTEC cell is prerequisite to understanding the advantages afforded by these materials. In a sodium-based AMTEC cell, the anode face of an anode/solid-electrolyte/cathode sandwich is exposed to Na vapor at a suitable pressure. Upon making contact with the solid electrolyte on the anode side, Na atoms oxidize to form Na+ ions and electrons. Na+ ions then travel through the electrolyte to the cathode. Na+ ions leave the electrolyte at the cathode/electrolyte interface and are reduced by electrons that have been conducted through an external electrical load from the anode to the cathode. Once the Na+ ions have been reduced to Na atoms, they travel through the cathode to vaporize into a volume where the Na vapor pressure is much lower than it is on the anode side. Thus, the cathode design is subject to competing requirements to be thin enough to allow transport of sodium to the low-pressure side, yet thick enough to afford adequate electronic conductivity. The concept underlying the development of the present mixed conducting electrode materials is the following: The constraint on the thickness of the cathode can be eased by incorporating Na+ -ionconducting material to facilitate transport of sodium through the cathode in ionic form. At the same time, by virtue of the electronically conducting material mixed with the ionically conducting material, reduction of Na+ ions to Na atoms can

  13. Effective thermal conductivity of damaged composites

    NASA Astrophysics Data System (ADS)

    Graham, Samuel, Jr.

    Ceramic matrix composites (CMCs) are susceptible to matrix cracking, fiber-matrix debonding, and oxidation processes as result of their application environments. These damage mechanisms act to degrade thermal conductivity and is a concern for many CMC applications. Prediction of this degradation relies on an accurate understanding of damage and thermal conductivity, and the development of analytical or numerical models. An experimental investigation into the degradation of thermal conductivity of CMCs was performed. In addition, an assessment was made of current micromechanics models for predicting thermal conductivity degradation. Experiments were performed on unidirectional reinforced Nicalon-LAS II glass-ceramic composites. Thermal conductivity was determined through flash diffusivity experiments. This procedure was also modified to treat orthotropic composite materials. Samples were subjected to mechanical loading-, oxidation-, and thermal shock-induced damage. The results showed that mechanical loading-induced damage resulted in no change in thermal conductivity transverse to the fiber axis and up to a 3.5% change parallel to the fibers. Mechanical loading followed by oxidation resulted in thermal conductivity degradation up to 26% and 10% transverse and parallel to the fibers, respectively. These data show the importance of the fiber-matrix interface in controlling both the longitudinal and transverse thermal conductivities of damaged composites. Predictions of thermal conductivity degradation parallel to the fiber direction were made with a shear-lag type micromechanics model. Results were in excellent agreement with experimental data. Thermal diffusivity data from isothermal oxidation and thermal shock experiments showed that this procedure is an effective nondestructive monitoring method. An assessment of transverse thermal conductivity rnicromechanics models was made through comparison with numerical solutions for random fiber inclusions with random

  14. Complexity and Control in Solitary Conductive PDEs

    NASA Astrophysics Data System (ADS)

    Ivancevic, Vladimir G.; Reid, Darryn J.

    2015-11-01

    In this Chapter, we review and analyze models of controlled complexity in nonlinear pulse conduction, ranging from the Hodgkin-Huxley action potentials propagating along neural fibers to rogue waves in optical fibers. The novel model proposed is an alternative to the Hodgkin-Huxley neural model in the form of the sine-Gordon wave equation. This new alternative explains pulse conduction in terms of general wave phenomena (such as kinks, solitons and breathers).

  15. Electrically conductive connection for an electrode

    SciTech Connect

    Hornack, Thomas R.; Chilko, Robert J.

    1986-01-01

    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.

  16. Active Bone Conduction Prosthesis: BonebridgeTM

    PubMed Central

    Zernotti, Mario E.; Sarasty, Andrea Bravo

    2015-01-01

    Introduction Bone conduction implants are indicated for patients with conductive and mixed hearing loss, as well as for patients with single-sided deafness (SSD). The transcutaneous technology avoids several complications of the percutaneous bone conduction implants including skin reaction, skin growth over the abutment, and wound infection. The Bonebridge (MED-EL, Austria) prosthesis is a semi-implantable hearing system: the BCI (Bone Conduction Implant) is the implantable part that contains the Bone Conduction-Floating Mass Transducer (BC-FMT), which applies the vibrations directly to the bone; the external component is the audio processor Amadé BB (MED-EL, Austria), which digitally processes the sound and sends the information through the coil to the internal part. Bonebridge may be implanted through three different approaches: the transmastoid, the retrosigmoid, or the middle fossa approach. Objective This systematic review aims to describe the world́s first active bone conduction implant system, Bonebridge, as well as describe the surgical techniques in the three possible approaches, showing results from implant centers in the world in terms of functional gain, speech reception thresholds and word recognition scores. Data Synthesis The authors searched the MEDLINE database using the key term Bonebridge. They selected only five publications to include in this systematic review. The review analyzes 20 patients that received Bonebridge implants with different approaches and pathologies. Conclusion Bonebridge is a solution for patients with conductive/mixed hearing loss and SSD with different surgical approaches, depending on their anatomy. The system imparts fewer complications than percutaneous bone conduction implants and shows proven benefits in speech discrimination and functional gain. PMID:26491482

  17. Thermal conductivity of Apollo 16 lunar fines

    NASA Technical Reports Server (NTRS)

    Cremers, C. J.; Hsia, H. S.

    1974-01-01

    The vacuum thermal conductivity of the Apollo 16 fines is presented as a function of temperature for the approximate range of diurnal temperatures on the moon. The density used is 1500 kg/cu m, which is approximately the density of the core-tube samples returned from the landing site. The thermal diffusivity was calculated from the conductivity, density, and specific heat and is also presented.

  18. Structure and Environment Influence in DNA Conduction

    NASA Technical Reports Server (NTRS)

    Adessi, C.; Walch, S.; Anantram, M. P.; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Results for transmission through a poly(G) DNA molecule are presented. We show that a modification of the rise of a B-DNA form can induce a shift of the conduction channel toward the valence one. We clearly prove that deformation of the backbone of the molecule has a significant influence on hole transport. Finally, we observe that the presence of ionic species, such Na, near the molecule can create new conduction channels.

  19. Active Bone Conduction Prosthesis: Bonebridge(TM).

    PubMed

    Zernotti, Mario E; Sarasty, Andrea Bravo

    2015-10-01

    Introduction Bone conduction implants are indicated for patients with conductive and mixed hearing loss, as well as for patients with single-sided deafness (SSD). The transcutaneous technology avoids several complications of the percutaneous bone conduction implants including skin reaction, skin growth over the abutment, and wound infection. The Bonebridge (MED-EL, Austria) prosthesis is a semi-implantable hearing system: the BCI (Bone Conduction Implant) is the implantable part that contains the Bone Conduction-Floating Mass Transducer (BC-FMT), which applies the vibrations directly to the bone; the external component is the audio processor Amadé BB (MED-EL, Austria), which digitally processes the sound and sends the information through the coil to the internal part. Bonebridge may be implanted through three different approaches: the transmastoid, the retrosigmoid, or the middle fossa approach. Objective This systematic review aims to describe the world́s first active bone conduction implant system, Bonebridge, as well as describe the surgical techniques in the three possible approaches, showing results from implant centers in the world in terms of functional gain, speech reception thresholds and word recognition scores. Data Synthesis The authors searched the MEDLINE database using the key term Bonebridge. They selected only five publications to include in this systematic review. The review analyzes 20 patients that received Bonebridge implants with different approaches and pathologies. Conclusion Bonebridge is a solution for patients with conductive/mixed hearing loss and SSD with different surgical approaches, depending on their anatomy. The system imparts fewer complications than percutaneous bone conduction implants and shows proven benefits in speech discrimination and functional gain. PMID:26491482

  20. Quantum conductance of carbon nanotubes with defects

    SciTech Connect

    Chico, L.; Benedict, L.X.; Louie, S.G.; Cohen, M.L. |

    1996-07-01

    We study the conductance of metallic carbon nanotubes with vacancies and pentagon-heptagon pair defects within the Landauer formalism. Using a tight-binding model and a Green{close_quote}s function technique to calculate the scattering matrix, we examine the one-dimensional to two-dimensional crossover in these systems and show the existence of metallic tube junctions in which the conductance is suppressed for symmetry reasons. {copyright} {ital 1996 The American Physical Society.}

  1. Thermal conductivity and diffusivity of soil

    SciTech Connect

    Sorour, M.M. ); Saleh, M.M.; Mahmoud, R.A. )

    1990-03-01

    The thermal conductivity and diffusivity of soil has been experimentally measured using the line heat source transient method. Representative samples of different textures were collected and analyzed from different localities and depths. The effect of temperatures, in the range of {minus}10{degrees}C {yields} 35{degrees}C and moisture content up to 40% on the conductivity and diffusivity were investigated. The results of this investigation indicate some interesting results and confirm some previously published data.

  2. Estimating Mesophyll Conductance in the Tropical Rainforest

    NASA Astrophysics Data System (ADS)

    Coughlin, I.

    2015-12-01

    In the current research modeling the carbon cycle, some of the biggest setbacks are methodological barriers to calculating the gross primary production (GPP) in the terrestrial biosphere. However, recent developments in high precision gas measurements now allow the use of COS as a potential tracer for determination of GPP, independently of CO2 .Since the tropics are implicated as being the source of the most significant reduction of carbon uptake by the majority of models, making accurate GPP measurements in the tropics is particularly important for carbon modeling. In order to constrain measurements of GPP in the tropics, carbonyl sulfide fluxes on a leaf chamber scale and a canopy-wide scale will be analyzed in a field site in the central Amazon. Accompanying this experiment, I am measuring the resistance of CO2 passing through the intercellular airspaces in the leaf to the sites of carboxylation, known as mesophyll conductance. Mesophyll conductance is poorly documented in the tropics, and remains a centrally limiting factor in plant uptake of COS and CO2 - with upward estimates of 40% of the CO2 diffusional limitation of photosynthesis hinging on mesophyll conductance (Warren, 2008). This makes mesophyll conductance comparable in magnitude to that of the stomatal conductance, suggesting that mesophyll conductance is one of the most fundamental measurements necessary for developing the predictive capacity of plants' response to ecosystem changes. Accurate measurements of the mesophyll conductance also lead to better informed models that can upscale assimilation measurements from leaf chambers, by providing quantitative constraints for modeling the uptake of carbonyl sulfide and carbon dioxide by the leaf. Additionally, since mesophyll conductance reacts to environmental variation, it can be used as an indicator for leaf stress. Measurements are taken using the 'variable J' technique, involving the use of combined fluorescence measurements and gas exchange data

  3. Conductive polymeric compositions for lithium batteries

    DOEpatents

    Angell, Charles A.; Xu, Wu

    2009-03-17

    Novel chain polymers comprising weakly basic anionic moieties chemically bound into a polyether backbone at controllable anionic separations are presented. Preferred polymers comprise orthoborate anions capped with dibasic acid residues, preferably oxalato or malonato acid residues. The conductivity of these polymers is found to be high relative to that of most conventional salt-in-polymer electrolytes. The conductivity at high temperatures and wide electrochemical window make these materials especially suitable as electrolytes for rechargeable lithium batteries.

  4. High quality transparent conducting oxide thin films

    DOEpatents

    Gessert, Timothy A.; Duenow, Joel N.; Barnes, Teresa; Coutts, Timothy J.

    2012-08-28

    A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

  5. Low Thermal Conductivity Thermal Barrier Coatings Developed

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming

    2003-01-01

    Thermal barrier coatings (TBCs) are used extensively in modern gas turbine engines to thermally insulate air-cooled metallic components from the hot gases in the engine. These coatings typically consist of a zirconia-yttria ceramic that has been applied by either plasma spraying or physical vapor deposition. Future engines will rely even more heavily on TBCs and will require materials that have even higher temperature capability with improved insulation (i.e., lower thermal conductivity even after many hours at high temperature). This report discusses new TBCs that have been developed with these future requirements in mind. The Ultra-Efficient Engine Technology Program at the NASA Glenn Research Center is funding this effort, which has been conducted primarily at Glenn with contractor support (GE and Howmet) for physical vapor deposition. As stated, the new TBC not only had to be more insulating but the insulation had to persist even after many hours of exposure-that is, the new TBC had to have both lower conductivity and improved sintering resistance. A new type of test rig was developed for this task. This new test approach used a laser to deliver a known high heat flux in an essentially uniform pattern to the surface of the coating, thereby establishing a realistic thermal gradient across its thickness. This gradient was determined from surface and backside pyrometry; and since the heat flux and coating thickness are known, this permitted continuous monitoring of thermal conductivity. Thus, this laser rig allowed very efficient screening of candidate low-conductivity, sinter-resistant TBCs. The coating-design approach selected for these new low-conductivity TBCs was to identify oxide dopants that had the potential to promote the formation of relatively large and stable groupings of defects known as defect clusters. This approach was used because it was felt that such clusters would reduce conductivity while enhancing stability. The approach proved to be

  6. Transparent conducting oxides and production thereof

    DOEpatents

    Gessert, Timothy A; Yoshida, Yuki; Coutts, Timothy J

    2014-05-27

    Transparent conducting oxides and production thereof are disclosed. An exemplary method of producing a transparent conducting oxide (TCO) material may comprise: providing a TCO target (110) doped with either a high-permittivity oxide or a low-permittivity oxide in a process chamber (100). The method may also comprise depositing a metal oxide on the target (110) to form a thin film having enhanced optical properties without substantially decreasing electrical quality.

  7. Transparent conducting oxides and production thereof

    DOEpatents

    Gessert, Timothy A.; Yoshida, Yuki; Coutts, Timothy J.

    2014-06-10

    Transparent conducting oxides and production thereof are disclosed. An exemplary method of producing a transparent conducting oxide (TCO) material may comprise: providing a TCO target doped with either a high-permittivity oxide or a low-permittivity oxide in a process chamber. The method may also comprise depositing a metal oxide on the target in the process chamber to form a thin film having enhanced optical properties without substantially decreasing electrical quality.

  8. Environment and Structure Influence in DNA Conduction

    NASA Technical Reports Server (NTRS)

    Adessi, C.; Walch, S.; Anantram, M. P.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Results for transmission through the poly(G) DNA molecule are presented. We show that (i) periodically arranged sodium counter-ions in close proximity to dry DNA gives rise to a new conduction channel and aperiodicity in the counter-ion sequence can lead to a significant reduction in conduction, (ii) modification of the rise of B-DNA induces a change in the width of the transmission window, and (iii) specifically designed sequences are predicted to show intrinsic resonant tunneling behavior.

  9. Local measurement of thermal conductivity and diffusivity

    SciTech Connect

    Hurley, David H.; Schley, Robert S.; Khafizov, Marat; Wendt, Brycen L.

    2015-12-01

    Simultaneous measurement of local thermal diffusivity and conductivity is demonstrated on a range of ceramic samples. This was accomplished by measuring the temperature field spatial profile of samples excited by an amplitude modulated continuous wave laser beam. A thin gold film is applied to the samples to ensure strong optical absorption and to establish a second boundary condition that introduces an expression containing the substrate thermal conductivity. The diffusivity and conductivity are obtained by comparing the measured phase profile of the temperature field to a continuum based model. A sensitivity analysis is used to identify the optimal film thickness for extracting the both substrate conductivity and diffusivity. Proof of principle studies were conducted on a range of samples having thermal properties that are representative of current and advanced accident tolerant nuclear fuels. It is shown that by including the Kapitza resistance as an additional fitting parameter, the measured conductivity and diffusivity of all the samples considered agree closely with literature values. Lastly, a distinguishing feature of this technique is that it does not require a priori knowledge of the optical spot size which greatly increases measurement reliability and reproducibility.

  10. Thermal Conductance of Nanoscale VOx Epitaxial Layers

    NASA Astrophysics Data System (ADS)

    Oh, Dong-Wook; Petrov, Ivan; Cahill, David

    2010-03-01

    We use time-domain thermoreflectance to measure the thermal conductance of VOx layers in epitaxial Pt/VOx/Pt structures. In particular, the metal-insulator-transition of VO2 at 70^oC allows us to systematically explore channels for heat transport between metals and correlated-electron systems. Pt/VOx/Pt layers are deposited on a sapphire substrates by reactive DC sputtering with O2 partial pressure varied from 0% to 13%. The thermal conductance has a strong dependence on thickness, 3-50 nm, and oxygen content, pure V to V2O5. The thermal conductance of ˜10 nm thick layers of V in series with the two Pt/V interfaces is 1 GW/m^2-K, comparable to what is expected based on the diffuse-mismatch model for electron transport at interfaces. The conductance of ˜10 nm thick layers of VO2 at room temperatures is remarkably high, 0.5 GW/m^2-K, for the series conductance of two metal-dielectric interfaces. At the metal-insulator-transition, the conductance of VO2 layers increases by only 10%, indicating that electrons in Pt and electrons in metallic VO2 are not strongly coupled.

  11. 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.

  12. Local measurement of thermal conductivity and diffusivity.

    PubMed

    Hurley, David H; Schley, Robert S; Khafizov, Marat; Wendt, Brycen L

    2015-12-01

    Simultaneous measurement of local thermal diffusivity and conductivity is demonstrated on a range of ceramic samples. This was accomplished by measuring the temperature field spatial profile of samples excited by an amplitude modulated continuous wave laser beam. A thin gold film is applied to the samples to ensure strong optical absorption and to establish a second boundary condition that introduces an expression containing the substrate thermal conductivity. The diffusivity and conductivity are obtained by comparing the measured phase profile of the temperature field to a continuum based model. A sensitivity analysis is used to identify the optimal film thickness for extracting the both substrate conductivity and diffusivity. Proof of principle studies were conducted on a range of samples having thermal properties that are representatives of current and advanced accident tolerant nuclear fuels. It is shown that by including the Kapitza resistance as an additional fitting parameter, the measured conductivity and diffusivity of all the samples considered agreed closely with the literature values. A distinguishing feature of this technique is that it does not require a priori knowledge of the optical spot size which greatly increases measurement reliability and reproducibility. PMID:26724041

  13. Thermal Conductivity of Alumina and Silica Nanofluids

    NASA Astrophysics Data System (ADS)

    Castellanos, Julian G. Bernal

    This thesis studies the effects of the base fluid, particle type/size, and volumetric concentration on the thermal conductivity of Alumina and Silica nanofluids. The effects of base fluid were observed by preparing samples using ethylene glycol (EG), water, and mixtures of EG/water as the base fluid and Al2O3 (10 nm) nanoparticles. The particles type/size and volumetric concentration effects were tested by preparing samples of nanofluids using Al2O3 (10nm), Al2O3 (150nm), SiO2 (15 nm), and SiO2 (80 nm) nanoparticles and ionized water as base fluid at different volumetric concentrations. All samples were mixed using a sonicator for 30 minutes and a water circulator to maintain the sample at room temperature. The thermal conductivity was measured using a Thermtest Transient Plane Source TPS 500S. The effects of gravity, Brownian motion and thermophoresis were also studied. EG produced the highest thermal conductivity enhancement out of all base fluids tested. Smaller particle size produced a higher enhancement of thermal conductivity, while the volumetric concentration did not have a significant effect in the thermal conductivity enhancement. Finally, gravity, Brownian diffusion and thermophoresis effects played a role in the total enhancement of the thermal conductivity. The nanoparticles were observed to settle rapidly after sonication suggesting gravity effects may play a significant role.

  14. Stretchable, porous, and conductive energy textiles.

    PubMed

    Hu, Liangbing; Pasta, Mauro; Mantia, Fabio La; Cui, Lifeng; Jeong, Sangmoo; Deshazer, Heather Dawn; Choi, Jang Wook; Han, Seung Min; Cui, Yi

    2010-02-10

    Recently there is strong interest in lightweight, flexible, and wearable electronics to meet the technological demands of modern society. Integrated energy storage devices of this type are a key area that is still significantly underdeveloped. Here, we describe wearable power devices using everyday textiles as the platform. With an extremely simple "dipping and drying" process using single-walled carbon nanotube (SWNT) ink, we produced highly conductive textiles with conductivity of 125 S cm(-1) and sheet resistance less than 1 Omega/sq. Such conductive textiles show outstanding flexibility and stretchability and demonstrate strong adhesion between the SWNTs and the textiles of interest. Supercapacitors made from these conductive textiles show high areal capacitance, up to 0.48F/cm(2), and high specific energy. We demonstrate the loading of pseudocapacitor materials into these conductive textiles that leads to a 24-fold increase of the areal capacitance of the device. These highly conductive textiles can provide new design opportunities for wearable electronics and energy storage applications. PMID:20050691

  15. Incoherent interlayer conduction in twisted bilayer graphene

    NASA Astrophysics Data System (ADS)

    Kim, Youngwook; Nam, S.-G.; Lee, H.-J.; Kim, Jun Sung; Yun, H.; Lee, S. W.; Son, M.; Choi, H. C.; Lee, D. S.; Kim, D. C.; Seo, S.

    2014-03-01

    Coherent motion of the electrons in the Bloch states often breaks down for the interlayer conduction in layered materials where the interlayer coupling is significantly reduced by e.g. large interlayer separation. Here, we report complete suppression of coherent conduction in twisted bilayer graphene even with an atomic length scale of layer separation. The interlayer conduction were investigated using a cross junction of monolayer graphene layers. The interlayer resistivity is much higher than the c-axis resistivity of Bernal-stacked graphite and exhibits strong dependence on temperature as well as on external electric fields. These results suggest that the graphene layers are significantly decoupled by rotation, and the incoherent electron tunneling is the main interlayer conduction channel. In this regime, the interlayer conduction is determined by the overlap of the Dirac Fermi surfaces (FS) from each layer. The angle dependence of the interlayer resistivity is found to be relatively strong at low temperatures, while it becomes moderate and monotonous at high temperatures. This demonstrates the importance of phonon-mediated conduction at high temperatures, which enhances the overlap between the momentum-mismatched FS's in twisted bilayer graphene.

  16. Thermal Conductivities of Crystalline Organic Semiconductors

    NASA Astrophysics Data System (ADS)

    Brill, Joseph

    2014-03-01

    As applications for organic semiconductors grow, it is becoming increasingly important to know their thermal conductivities, k. For example, for sub-micron electronic devices, values of k>k0 ~ 5 mW/cm/K are needed, while values kconductivities below k0, many molecular organic crystals also have values of k below this value. We have started measurements of both the in-plane and interplane thermal diffusivities of layered crystalline organic semiconductors using frequency[2] and position dependent[3] ac-calorimetry; the thermal conductivities are then determined from the specific heats measured with differential scanning calorimetry. For rubrene, which has kconductivity is several times smaller than the in-plane value, although its temperature dependence indicates that the phonon mean-free path is at least a few layers.[4] On the other hand, the in-plane thermal conductivity of TIPS-pentacene,[5] is several times greater than k0, similar to that of the quasi-one dimensional organic metal TTF-TCNQ.[6] Remarkably, its interlayer thermal conductivity is several times larger than its in-plane value,[7] perhaps due to interactions between the large (triisopropylsilylethynyl) side groups on the pentacene backbone. Research done with Hao Zhang and Yulong Yao and supported by NSF grants DMR-0800367, EPS-0814194, and DMR-1262261.

  17. Proton conductivity in ampullae of Lorenzini jelly

    PubMed Central

    Josberger, Erik E.; Hassanzadeh, Pegah; Deng, Yingxin; Sohn, Joel; Rego, Michael J.; Amemiya, Chris T.; Rolandi, Marco

    2016-01-01

    In 1678, Stefano Lorenzini first described a network of organs of unknown function in the torpedo ray—the ampullae of Lorenzini (AoL). An individual ampulla consists of a pore on the skin that is open to the environment, a canal containing a jelly and leading to an alveolus with a series of electrosensing cells. The role of the AoL remained a mystery for almost 300 years until research demonstrated that skates, sharks, and rays detect very weak electric fields produced by a potential prey. The AoL jelly likely contributes to this electrosensing function, yet the exact details of this contribution remain unclear. We measure the proton conductivity of the AoL jelly extracted from skates and sharks. The room-temperature proton conductivity of the AoL jelly is very high at 2 ± 1 mS/cm. This conductivity is only 40-fold lower than the current state-of-the-art proton-conducting polymer Nafion, and it is the highest reported for a biological material so far. We suggest that keratan sulfate, identified previously in the AoL jelly and confirmed here, may contribute to the high proton conductivity of the AoL jelly with its sulfate groups—acid groups and proton donors. We hope that the observed high proton conductivity of the AoL jelly may contribute to future studies of the AoL function. PMID:27386543

  18. Polyethylene nanofibres with very high thermal conductivities.

    PubMed

    Shen, Sheng; Henry, Asegun; Tong, Jonathan; Zheng, Ruiting; Chen, Gang

    2010-04-01

    Bulk polymers are generally regarded as thermal insulators, and typically have thermal conductivities on the order of 0.1 W m(-1) K(-1). However, recent work suggests that individual chains of polyethylene--the simplest and most widely used polymer--can have extremely high thermal conductivity. Practical applications of these polymers may also require that the individual chains form fibres or films. Here, we report the fabrication of high-quality ultra-drawn polyethylene nanofibres with diameters of 50-500 nm and lengths up to tens of millimetres. The thermal conductivity of the nanofibres was found to be as high as approximately 104 W m(-1) K(-1), which is larger than the conductivities of about half of the pure metals. The high thermal conductivity is attributed to the restructuring of the polymer chains by stretching, which improves the fibre quality toward an 'ideal' single crystalline fibre. Such thermally conductive polymers are potentially useful as heat spreaders and could supplement conventional metallic heat-transfer materials, which are used in applications such as solar hot-water collectors, heat exchangers and electronic packaging. PMID:20208547

  19. Proton conductivity in ampullae of Lorenzini jelly.

    PubMed

    Josberger, Erik E; Hassanzadeh, Pegah; Deng, Yingxin; Sohn, Joel; Rego, Michael J; Amemiya, Chris T; Rolandi, Marco

    2016-05-01

    In 1678, Stefano Lorenzini first described a network of organs of unknown function in the torpedo ray-the ampullae of Lorenzini (AoL). An individual ampulla consists of a pore on the skin that is open to the environment, a canal containing a jelly and leading to an alveolus with a series of electrosensing cells. The role of the AoL remained a mystery for almost 300 years until research demonstrated that skates, sharks, and rays detect very weak electric fields produced by a potential prey. The AoL jelly likely contributes to this electrosensing function, yet the exact details of this contribution remain unclear. We measure the proton conductivity of the AoL jelly extracted from skates and sharks. The room-temperature proton conductivity of the AoL jelly is very high at 2 ± 1 mS/cm. This conductivity is only 40-fold lower than the current state-of-the-art proton-conducting polymer Nafion, and it is the highest reported for a biological material so far. We suggest that keratan sulfate, identified previously in the AoL jelly and confirmed here, may contribute to the high proton conductivity of the AoL jelly with its sulfate groups-acid groups and proton donors. We hope that the observed high proton conductivity of the AoL jelly may contribute to future studies of the AoL function. PMID:27386543

  20. Cation Defects and Conductivity in Transparent Oxides

    SciTech Connect

    Exarhos, Gregory J.; Windisch, Charles F.; Ferris, Kim F.; Owings, Robert R.

    2007-10-24

    High quality doped zinc oxide and mixed transition metal spinel oxide films have been deposited by means of sputter deposition from metal and metal oxide targets, and by spin casting from aqueous or alcoholic precursor solutions. Deposition conditions and post-deposition processing are found to alter cation oxidation states and their distributions in both oxide materials resulting in marked changes to both optical transmission and electrical response. For ZnO, partial reduction of the neat or doped material by hydrogen treatment of the heated film or by electrochemical processing renders the oxide n-type conducting. Continued reduction was found to diminish conductivity. In contrast, oxidation of the infrared transparent p-type spinel conductors typified by NiCo2O4 was found to increase conductivity. The disparate behavior of these two materials is caused in part by the sign of the charge carrier and by the existence of two different charge transport mechanisms that are identified as free carrier conduction and polaron hopping. While much work has been reported concerning structure/property relationships in the free carrier conducting oxides, there is a significantly smaller body of information on transparent polaron conductors. In this paper, we identify key parameters that promote conductivity in mixed metal spinel oxides and compare their behavior with that of the free carrier TCO’s.

  1. Local measurement of thermal conductivity and diffusivity

    NASA Astrophysics Data System (ADS)

    Hurley, David H.; Schley, Robert S.; Khafizov, Marat; Wendt, Brycen L.

    2015-12-01

    Simultaneous measurement of local thermal diffusivity and conductivity is demonstrated on a range of ceramic samples. This was accomplished by measuring the temperature field spatial profile of samples excited by an amplitude modulated continuous wave laser beam. A thin gold film is applied to the samples to ensure strong optical absorption and to establish a second boundary condition that introduces an expression containing the substrate thermal conductivity. The diffusivity and conductivity are obtained by comparing the measured phase profile of the temperature field to a continuum based model. A sensitivity analysis is used to identify the optimal film thickness for extracting the both substrate conductivity and diffusivity. Proof of principle studies were conducted on a range of samples having thermal properties that are representatives of current and advanced accident tolerant nuclear fuels. It is shown that by including the Kapitza resistance as an additional fitting parameter, the measured conductivity and diffusivity of all the samples considered agreed closely with the literature values. A distinguishing feature of this technique is that it does not require a priori knowledge of the optical spot size which greatly increases measurement reliability and reproducibility.

  2. Local measurement of thermal conductivity and diffusivity

    SciTech Connect

    Hurley, David H.; Schley, Robert S.; Khafizov, Marat; Wendt, Brycen L.

    2015-12-15

    Simultaneous measurement of local thermal diffusivity and conductivity is demonstrated on a range of ceramic samples. This was accomplished by measuring the temperature field spatial profile of samples excited by an amplitude modulated continuous wave laser beam. A thin gold film is applied to the samples to ensure strong optical absorption and to establish a second boundary condition that introduces an expression containing the substrate thermal conductivity. The diffusivity and conductivity are obtained by comparing the measured phase profile of the temperature field to a continuum based model. A sensitivity analysis is used to identify the optimal film thickness for extracting the both substrate conductivity and diffusivity. Proof of principle studies were conducted on a range of samples having thermal properties that are representatives of current and advanced accident tolerant nuclear fuels. It is shown that by including the Kapitza resistance as an additional fitting parameter, the measured conductivity and diffusivity of all the samples considered agreed closely with the literature values. A distinguishing feature of this technique is that it does not require a priori knowledge of the optical spot size which greatly increases measurement reliability and reproducibility.

  3. Local measurement of thermal conductivity and diffusivity

    DOE PAGESBeta

    Hurley, David H.; Schley, Robert S.; Khafizov, Marat; Wendt, Brycen L.

    2015-12-01

    Simultaneous measurement of local thermal diffusivity and conductivity is demonstrated on a range of ceramic samples. This was accomplished by measuring the temperature field spatial profile of samples excited by an amplitude modulated continuous wave laser beam. A thin gold film is applied to the samples to ensure strong optical absorption and to establish a second boundary condition that introduces an expression containing the substrate thermal conductivity. The diffusivity and conductivity are obtained by comparing the measured phase profile of the temperature field to a continuum based model. A sensitivity analysis is used to identify the optimal film thickness formore » extracting the both substrate conductivity and diffusivity. Proof of principle studies were conducted on a range of samples having thermal properties that are representative of current and advanced accident tolerant nuclear fuels. It is shown that by including the Kapitza resistance as an additional fitting parameter, the measured conductivity and diffusivity of all the samples considered agree closely with literature values. Lastly, a distinguishing feature of this technique is that it does not require a priori knowledge of the optical spot size which greatly increases measurement reliability and reproducibility.« less

  4. Single-atom conductance of Y

    NASA Astrophysics Data System (ADS)

    Parveen, Nadia; Ishino, Yuji; Kurokawa, Shu; Sakai, Akira

    2016-05-01

    Y is a trivalent metal like Al but has one d valence electron instead of one p valence electron in Al. This makes a single-atom contact of Y a suitable playground for investigating how d valence electrons contribute to the single-atom conductance. In this paper, we present the results of our theoretical and experimental studies of the single-atom conductance of Y. We carried out conductance measurements on Y contacts and found that the conductance histogram observed at 4 K exhibits a single broad peak at 1.9G0. We also calculated the electron transmission through a Y single-atom contact and obtained the total transmission 1.75 at the Fermi level. Both our theoretical and experimental findings consistently indicate that the single-atom conductance of Y lies at (1.8 - 1.9)G0, which is nearly twice as high as that of Al. This increase in the single-atom conductance is due to the second and the third eigenchannels of Y which accomplish higher transmission compared to those of Al. We found that the difference in the contours of sd- and sp-eigenchannels can account for the higher transmission of the sd-eigenchannels.

  5. A singlechip-computer-controlled conductivity meter based on conductance-frequency transformation

    NASA Astrophysics Data System (ADS)

    Chen, Wenxiang; Hong, Baocai

    2005-02-01

    A portable conductivity meter controlled by singlechip computer was designed. The instrument uses conductance-frequency transformation method to measure the conductivity of solution. The circuitry is simple and reliable. Another feature of the instrument is that the temperature compensation is realised by changing counting time of the timing counter. The theoretical based and the usage of temperature compensation are narrated.

  6. Conductance tomography of conductive filaments in intrinsic silicon-rich silica RRAM.

    PubMed

    Buckwell, Mark; Montesi, Luca; Hudziak, Stephen; Mehonic, Adnan; Kenyon, Anthony J

    2015-11-21

    We present results from an imaging study of filamentary conduction in silicon suboxide resistive RAM devices. We used a conductive atomic force microscope to etch through devices while measuring current, allowing us to produce tomograms of conductive filaments. To our knowledge this is the first report of such measurements in an intrinsic resistance switching material. PMID:26482563

  7. Observation of quantized conductance in neutral matter

    NASA Astrophysics Data System (ADS)

    Krinner, Sebastian; Stadler, David; Husmann, Dominik; Brantut, Jean-Philippe; Esslinger, Tilman

    2015-01-01

    In transport experiments, the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps, with a size determined solely by Planck's constant h. Observations of quantized steps in electrical conductance have provided important insights into the physics of mesoscopic systems and have allowed the development of quantum electronic devices. Even though quantized conductance should not rely on the presence of electric charges, it has never been observed for neutral, massive particles. In its most fundamental form, it requires a quantum-degenerate Fermi gas, a ballistic and adiabatic transport channel, and a constriction with dimensions comparable to the Fermi wavelength. Here we report the observation of quantized conductance in the transport of neutral atoms driven by a chemical potential bias. The atoms are in an ultraballistic regime, where their mean free path exceeds not only the size of the transport channel, but also the size of the entire system, including the atom reservoirs. We use high-resolution lithography to shape light potentials that realize either a quantum point contact or a quantum wire for atoms. These constrictions are imprinted on a quasi-two-dimensional ballistic channel connecting the reservoirs. By varying either a gate potential or the transverse confinement of the constrictions, we observe distinct plateaux in the atom conductance. The conductance in the first plateau is found to be equal to the universal conductance quantum, 1/h. We use Landauer's formula to model our results and find good agreement for low gate potentials, with all parameters determined a priori. Our experiment lets us investigate quantum conductors with wide control not only over the channel geometry, but also over the reservoir properties, such as interaction strength, size and thermalization rate.

  8. Heat conductivity of DNA double helix

    PubMed Central

    Savin, Alexander V.; Mazo, Mikhail A.; Kikot, Irina P.; Manevitch, Leonid I.; Onufriev, Alexey V.

    2015-01-01

    Thermal conductivity of isolated single molecule DNA fragments is of importance for nanotechnology, but has not yet been measured experimentally. Theoretical estimates based on simplified (1D) models predict anomalously high thermal conductivity. To investigate thermal properties of single molecule DNA we have developed a 3D coarse-grained (CG) model that retains the realism of the full all-atom description, but is significantly more efficient. Within the proposed model each nucleotide is represented by 6 particles or grains; the grains interact via effective potentials inferred from classical molecular dynamics (MD) trajectories based on a well-established all-atom potential function. Comparisons of 10 ns long MD trajectories between the CG and the corresponding all-atom model show similar root-mean-square deviations from the canonical B-form DNA, and similar structural fluctuations. At the same time, the CG model is 10 to 100 times faster depending on the length of the DNA fragment in the simulation. Analysis of dispersion curves derived from the CG model yields longitudinal sound velocity and torsional stiffness in close agreement with existing experiments. The computational efficiency of the CG model makes it possible to calculate thermal conductivity of a single DNA molecule not yet available experimentally. For a uniform (polyG-polyC) DNA, the estimated conductivity coefficient is 0.3 W/mK which is half the value of thermal conductivity for water. This result is in stark contrast with estimates of thermal conductivity for simplified, effectively 1D chains (”beads on a spring”) that predict anomalous (infinite) thermal conductivity. Thus, full 3D character of DNA double-helix retained in the proposed model appears to be essential for describing its thermal properties at a single molecule level. PMID:26207085

  9. Thermal conductivity of zirconia thermal barrier coatings

    SciTech Connect

    Dinwiddie, R.B.; Beecher, S.C.; Nagaraj, B.A.; Moore, C.S.

    1995-10-01

    Thermal barrier coatings (TBC`s) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC`s is of primary importance. Physical vapor deposition (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard powder or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increases upon exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as-fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings.

  10. Peat hydraulic conductivity in different landuses

    NASA Astrophysics Data System (ADS)

    Mustamo, Pirkko; Hyvärinen, Maarit; Ronkanen, Anna-Kaisa; Kløve, Bjørn

    2013-04-01

    Information on hydraulic conductivity and water retention properties of peatlands is needed, e.g., for modelling hydrology and soil carbon balance of peat soils. Ability to model the behaviour of peat soils, especially those drained for agricultural use, is important as cultivated peatlands act as a major source of CO2 and N2O emissions in Nordic countries. Peat soil hydraulic conductivity and water retention properties vary greatly, and their relationship to soil depth and degree of decomposition is not straightforward. The aim of this study was to produce new information about peat physical properties in different land uses and the relationship between peat soil hydraulic conductivity and variables such as soil porosity and degree of humification. Peat hydraulic conductivity was measured in situ with infiltrometer (direct push piezometer) in six study sites (two pristine bogs, two sites drained for forestry, a cultivated peat land site and a peat extraction site). Measurements were made in several depths according to soil profile. To examine relationship of soil properties and the hydraulic conductivity, undisturbed peat cores of known volume and also disturbed peat samples were collected from the study sites for determination of von Post humification factor, ash content, porosity and bulk density. Surface layer of the agricultural site had high ash content and bulk density and low porosity compared to the soil beneath it and the soil in other study sites. This was due to added sand and compaction by agricultural practice. Bog, in contrast, had very low bulk density and high porosity. Results show a great variation in hydraulic conductivity within the study sites even when the observations were in the same soil layer. Hydraulic conductivity was lowest in the peat extraction site and the agricultural site, and had higher correlation with study site (= landuse) and the measured layer than with soil porosity.

  11. Thermal conductivity of uterine tissue in vitro

    NASA Astrophysics Data System (ADS)

    Olsrud, Johan; Friberg, Britt; Ahlgren, Mats; Persson, Bertil R. R.

    1998-08-01

    Thermotherapy of the uterus has emerged as an alternative to hysterectomy in the treatment of menorrhagia, from whence it follows that the thermal properties of uterine tissue have become of importance. This study presents measurements of the thermal conductivity and the water content of uterine tissue in vitro. A steady-state thermal conductivity apparatus, based on the comparison of test samples with a material with known thermal conductivity, is described. Measurements were conducted on tissue samples from eleven patients, directly after hysterectomy. Samples with and without endometrium, as well as coagulated samples, were examined. The thermal conductivity of myometrial tissue was found to be and the corresponding water content was % . Measurements on samples with both endometrium and myometrium showed similar thermal conductivity (, ) and water content (%, ). It was also indicated that coagulation causes dehydration, resulting in a lower thermal conductivity.

  12. Nanoelectrode lithography using flexible conductive molds

    NASA Astrophysics Data System (ADS)

    Li, Y. F.; Chen, K. H.; Ootera, Y.; Toshiyoshi, H.; Fujita, H.

    2015-11-01

    This paper reports a pattern transfer technique based on an anodic oxidation reaction (AOR) using two kinds of flexible conductive molds (FCMs). This technique enables fine pattern transfer on an uneven surface with 1.8-µm-deep recesses and also improves the transfer uniformity on a flat surface. Both FCMs consist of a base, a flexible insulating pattern on the top of the base and a nanometric thick metal film deposited on the top of the base and the insulating pattern as a conductive layer. Oxide patterns corresponding to the conductive pattern are transferred on the surface of the target material via an AOR between the FCM and the target. The flexibility of the base and the insulating pattern not only enables the FCM to come close enough to the recess of the target material with an uneven surface to generate oxide patterns but also enables a uniform electrical contact between the FCM and the target material with a flat surface to improve transfer uniformity. The conductive pattern on the FCM makes it possible to generate oxide patterns on the surface of the target material in a resistless process via the AOR. A microelectromechanical system technique is used to fabricate the proposed FCMs, and two kinds of FCMs are developed: A film-type FCM with a conductive pattern whose line width is from 5 to 20 µm and a resin-type FCM with a 200-nm half-pitch conductive pattern. Oxide patterns with a line width and a half pitch corresponding to the conductive patterns of the two developed FCMs were collectively transferred on an uneven surface with 1.8-µm-deep recesses and a flat surface of silicon substrate in a millimeter-scale area.

  13. The electrical conductivity of sodium polysulfide melts

    SciTech Connect

    Meihui Wang

    1992-06-01

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

  14. Anomalous thermal conductivity of monolayer boron nitride

    NASA Astrophysics Data System (ADS)

    Tabarraei, Alireza; Wang, Xiaonan

    2016-05-01

    In this paper, we use nonequilibrium molecular dynamics modeling to investigate the thermal properties of monolayer hexagonal boron nitride nanoribbons under uniaxial strain along their longitudinal axis. Our simulations predict that hexagonal boron nitride shows an anomalous thermal response to the applied uniaxial strain. Contrary to three dimensional materials, under uniaxial stretching, the thermal conductivity of boron nitride nanoribbons first increases rather than decreasing until it reaches its peak value and then starts decreasing. Under compressive strain, the thermal conductivity of monolayer boron nitride ribbons monolithically reduces rather than increasing. We use phonon spectrum and dispersion curves to investigate the mechanism responsible for the unexpected behavior. Our molecular dynamics modeling and density functional theory results show that application of longitudinal tensile strain leads to the reduction of the group velocities of longitudinal and transverse acoustic modes. Such a phonon softening mechanism acts to reduce the thermal conductivity of the nanoribbons. On the other hand, a significant increase in the group velocity (stiffening) of the flexural acoustic modes is observed, which counteracts the phonon softening effects of the longitudinal and transverse modes. The total thermal conductivity of the ribbons is a result of competition between these two mechanisms. At low tensile strain, the stiffening mechanism overcomes the softening mechanism which leads to an increase in the thermal conductivity. At higher tensile strain, the softening mechanism supersedes the stiffening and the thermal conductivity slightly reduces. Our simulations show that the decrease in the thermal conductivity under compressive strain is attributed to the formation of buckling defects which reduces the phonon mean free path.

  15. Thermal conductivity of zirconia thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Dinwiddie, R. B.; Beecher, S. C.; Nagaraj, B. A.; Moore, C. S.

    1995-01-01

    Thermal barrier coatings (TBC's) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC's is of primary importance. Physical vapor description (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard power or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increase upon being exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings. The high temperature thermal diffusivity data indicates that if these coatings reach a temperature above

  16. Thermal conductivity of zirconia thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Dinwiddie, R. B.; Beecher, S. C.; Nagaraj, B. A.; Moore, C. S.

    1995-01-01

    Thermal barrier coatings (TBC's) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC's is of primary importance. Physical vapor deposition (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard powder or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increases upon exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as-fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings. The high temperature thermal diffusivity data indicate that if these coatings reach a temperature above 1100 C

  17. Ionic surface electrical conductivity in sandstone

    NASA Astrophysics Data System (ADS)

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

    1994-11-01

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

  18. Advances in the understanding of conduction disturbances.

    PubMed

    Kulbertus, H E

    1978-09-01

    The interest towards intraventricular conduction defects started some 10 yr after the introduction of the string galvanometer by Einthoven. As early as 1910, it was known that conduction blockade could occur along either branch of the intraventricular conducting pathway. It took some 20 yr to identify properly the electrocardiographic manifestations of right and left bundle branch blocks. A further 30 yr were needed to obtain a sound correlation between these functional disorders and the presence of anatomical lesions. The more recent introduction of the concept of left hemiblocks further improved our understanding of intraventricular conduction defects. The latter concept is based on the hypothesis of the anatomical and functional bifascicularity of the left bundle branch, a hypothesis which cannot be accepted without some reservations. Later developments indicated that left hemiblocks associated with right bundle branch block represent manifestations of bilateral conduction disturbances (incomplete bilateral bundle branch block). Such an association may constitute a forerunner of complete atrioventricular block, or an indicator of the possibility of sudden death. Whether these complications occur frequently or unfrequently in the setting of incomplete bilateral bundle branch block remains an unsettled question. PMID:699953

  19. Conducting tissues and phyletic relationships of bryophytes.

    PubMed Central

    Ligrone, R; Ducket, J G; Renzaglia, K S

    2000-01-01

    Internal specialized conducting tissues, if present, are restricted to the gametophytic generation in liverworts while they may occur in both generations in mosses. Conducting tissues are unknown in the anthocerotes. Water-conducting cells (WCCs) with walls perforated by plasmodesma-derived pores occur in the Calobryales and Pallaviciniaceae (Metzgeriales among liverworts and in Takakia among mosses. Imperforate WCCs (hydroids) are present in bryoid mosses. A polarized cytoplasmic organization and a distinctive axial system of microtubules is present in the highly specialized food-conducting cells of polytrichaceous mosses (leptoids) and in less specialized parenchyma cells of the leafy stem and seta in other mosses including Sphagnumn. A similar organization, suggested to reflect specialization in long-distance symplasmic transport of nutrients, also occurs in other parts of the plant in mosses, including rhizoids and caulonemata, and may be observed in thallus parenchyma cells of liverworts. Perforate WCCs in the Calobryales, Metzgeriales and Takakia, and hydroids in bryoid mosses, probably evolved independently Because of fundamental differences in developmental design, homology of any of these cells with tracheids is highly unlikely. Likewise, putative food-conducting of bryophytes present highly distinctive characteristics and cannot be considered homologous with the sieve cells of tracheophytes. PMID:10905610

  20. Heat Conduction in Novel Electronic Films

    NASA Astrophysics Data System (ADS)

    Goodson, Kenneth E.; Ju, Y. Sungtaek

    1999-08-01

    Heat conduction in novel electronic films influences the performance and reliability of micromachined transistors, lasers, sensors, and actuators. This article reviews experimental and theoretical research on heat conduction in single-crystal semiconducting and superconducting films and superlattices, polycrystalline diamond films, and highly disordered organic and oxide films. The thermal properties of these films can differ dramatically from those of bulk samples owing to the dependence of the material structure and purity on film processing conditions and to the scattering of heat carriers at material boundaries. Predictions and data show that phonon scattering and transmission at boundaries strongly influence the thermal conductivities of single-crystal films and superlattices, although more work is needed to resolve the importance of strain-induced lattice defects. For polycrystalline films, phonon scattering on grain boundaries and associated defects causes the thermal conductivity to be strongly anisotropic and nonhomogeneous. For highly disordered films, preliminary studies have illustrated the influences of impurities on the volumetric heat capacity and, for the case of organic films, molecular orientation on the conductivity anisotropy. More work on disordered films needs to resolve the interplay among atomic-scale disorder, porosity, partial crystallinity, and molecular orientation.

  1. Observation of quantized conductance in neutral matter

    NASA Astrophysics Data System (ADS)

    Husmann, Dominik; Krinner, Sebastian; Lebrat, Martin; Grenier, Charles; Nakajima, Shuta; Häusler, Samuel; Brantut, Jean-Philippe; Esslinger, Tilman

    2015-05-01

    In transport experiments, the quantum nature of matter becomes directly evident when changes in conductance occur only in discrete steps, with a size determined solely by Planck's constant h. Here we report the observation of quantized conductance in the transport of neutral atoms driven by a chemical potential bias. We use high-resolution lithography to shape light potentials that realize either a quantum point contact or a quantum wire for atoms. These constrictions are imprinted on a quasi-two-dimensional ballistic channel connecting the reservoirs. By varying either a gate potential or the transverse confinement of the constrictions, we observe distinct plateaux in the atom conductance. The conductance in the first plateau is found to be equal to the universal conductance quantum, 1/h. We use Landauer's formula to model our results and find good agreement for low gate potentials, with all parameters determined a priori. We eventually explore the behavior of a strongly interacting Fermi gas in the same configuration, and the consequences of the emergence of superfluidity.

  2. 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.

  3. Thermal conductivity behavior of superatom molecular crystals

    NASA Astrophysics Data System (ADS)

    Ong, Wee-Liat; O'Brien, Evan; Dougherty, Patrick; Epstein, Jillian; Higgs, C. Fred; McGaughey, Alan; Roy, Xavier; Malen, Jonathan

    The room temperature thermal conductivity of several superatom molecular crystals (SMCs) are measured and found to be below 0.3 W/mK. The trend of room temperature thermal conductivity of the different crystals agree well with their sound speeds obtained independently using nano-indentation. These crystals, however, can exhibit non-crystalline thermal conductivity behavior depending on their constituent elements. A superatom is a cluster of atoms that acts as a stable entity [e.g., fullerenes (C60)]. By careful mixing and assembling these nano-sized superatoms, the resulting superatom-assembled materials hold promises for improving various technological devices. Organic-inorganic superatoms can assemble into unary SMCs or co-crystallized with C60 superatoms into binary SMCs. Thermal transport is of considerable interest with possible new physics in these hierarchically atomic precise crystals in the low temperature regime. The thermal conductivity of the SMCs are measured using the frequency domain thermoreflectance setup. Unary SMCs exhibit an almost invariant thermal conductivity down to a temperature of 150 K. Binary SMCs, however, can either show a crystalline-like increase or an amorphous-like decrease with decreasing temperature.

  4. Nonlinear alternating current conduction in polycrystalline manganites

    NASA Astrophysics Data System (ADS)

    Ghosh, T. N.; Nandi, U. N.; Jana, D.; Dey, K.; Giri, S.

    2014-06-01

    The real part of ac conductance Σ(T, f) of yttrium-doped mixed-valent polycrystalline manganite systems La1-x -yYyCaxMnO3 with x = 0.33 and 0.05 and y = 0.07 and iron doped LaMn1-xFexO3 with x = 0.15 is measured as a function of frequency f by varying zero-frequency Ohmic conductance Σ0 by T. The former shows a metal-insulator transition, whereas the latter exhibits insulating character throughout the measured temperature range. At a fixed temperature T, Σ(T, f) remains almost constant to the value Σ0 up to a certain frequency, known as the onset frequency fc and increases from Σ0 as frequency is increased from fc. Scaled appropriately, the data for Σ(T, f) at different T fall on the same universal curve, indicating the existence of a general scaling formalism for the ac conductance. fc scales with Σ0 as fc˜Σ0xf, where xf is the nonlinearity exponent characterising the onset. With the help of data for ac conduction, it is shown that xf is very much phase sensitive and can be used to characterize the different phases in a manganite system originated due to change in temperature or disorder. Scaling theories and existing theoretical models are used to analyze the results of ac conduction and the nonlinearity exponent xf.

  5. Engineering thermal conductivity in polymer blends

    NASA Astrophysics Data System (ADS)

    Rashidi, Vahid; Coyle, Eleanor; Kieffer, John; Pipe, Kevin

    Weak inter-chain bonding in polymers is believed to be a bottleneck for both thermal conductivity and mechanical strength. Most polymers have low thermal conductivity (~0.1 W/mK), hindering their performance in applications for which thermal management is critical (e.g., electronics packaging). In this work, we use computational methods to study how hydrogen bonding between polymer chains as well as water content can be used to engineer thermal transport in bulk polymers. We examine how changes in the number of hydrogen bonds, chain elongation, density, and vibrational density of states correlate with changes in thermal conductivity for polymer blends composed of different relative constituent fractions. We also consider the effects of bond strength, tacticity, and polymer chain mass. For certain blend fractions, we observe large increases in thermal conductivity, and we analyze these increases in terms of modifications to chain chemistry (e.g., inter-chain bonding) and chain morphology (e.g., chain alignment and radius of gyration). We observe that increasing the number of hydrogen bonds in the system results in better packing as well as better chain alignment and elongation that contribute to enhanced thermal conductivity. The Air Force Office of Scientific Research, Grant No. FA9550-14-1-0010.

  6. Increasing the conductivity of crystalline polymer electrolytes.

    PubMed

    Christie, Alasdair M; Lilley, Scott J; Staunton, Edward; Andreev, Yuri G; Bruce, Peter G

    2005-01-01

    Polymer electrolytes consist of salts dissolved in polymers (for example, polyethylene oxide, PEO), and represent a unique class of solid coordination compounds. They have potential applications in a diverse range of all-solid-state devices, such as rechargeable lithium batteries, flexible electrochromic displays and smart windows. For 30 years, attention was focused on amorphous polymer electrolytes in the belief that crystalline polymer:salt complexes were insulators. This view has been overturned recently by demonstrating ionic conductivity in the crystalline complexes PEO6:LiXF6 (X = P, As, Sb); however, the conductivities were relatively low. Here we demonstrate an increase of 1.5 orders of magnitude in the conductivity of these materials by replacing a small proportion of the XF6- anions in the crystal structure with isovalent N(SO2CF3)2- ions. We suggest that the larger and more irregularly shaped anions disrupt the potential around the Li+ ions, thus enhancing the ionic conductivity in a manner somewhat analogous to the AgBr(1-x)I(x) ionic conductors. The demonstration that doping strategies can enhance the conductivity of crystalline polymer electrolytes represents a significant advance towards the technological exploitation of such materials. PMID:15635406

  7. Conductive Carbon Coatings for Electrode Materials

    SciTech Connect

    Doeff, Marca M.; Kostecki, Robert; Wilcox, James; Lau, Grace

    2007-07-13

    A simple method for optimizing the carbon coatings on non-conductive battery cathode material powders has been developed at Lawrence Berkeley National Laboratory. The enhancement of the electronic conductivity of carbon coating enables minimization of the amount of carbon in the composites, allowing improvements in battery rate capability without compromising energy density. The invention is applicable to LiFePO{sub 4} and other cathode materials used in lithium ion or lithium metal batteries for high power applications such as power tools and hybrid or plug-in hybrid electric vehicles. The market for lithium ion batteries in consumer applications is currently $5 billion/year. Additionally, lithium ion battery sales for vehicular applications are projected to capture 5% of the hybrid and electric vehicle market by 2010, and 36% by 2015 (http://www.greencarcongress.com). LiFePO{sub 4} suffers from low intrinsic rate capability, which has been ascribed to the low electronic conductivity (10{sup -9} S cm{sup -1}). One of the most promising approaches to overcome this problem is the addition of conductive carbon. Co-synthesis methods are generally the most practical route for carbon coating particles. At the relatively low temperatures (<800 C) required to make LiFePO{sub 4}, however, only poorly conductive disordered carbons are produced from organic precursors. Thus, the carbon content has to be high to produce the desired enhancement in rate capability, which decreases the cathode energy density.

  8. Conductance spectroscopy of topological superconductor wire junctions

    NASA Astrophysics Data System (ADS)

    Setiawan, F.; Brydon, Philip; Sau, Jay

    We study the zero-temperature transport properties of one-dimensional normal metal-superconductor (NS) junctions with topological superconductors across their topological transitions. Working within the Blonder-Tinkham-Klapwijk (BTK) formalism generalized for topological NS junctions, we analytically calculate the differential conductance for tunneling into two models of a topological superconductor: a spinless intrinsic p-wave superconductor and a spin-orbit-coupled s-wave superconductor in a Zeeman field. The zero-bias conductance takes nonuniversal values in the nontopological phase while it is robustly quantized at 2e2 / h in the topological regime. Despite this quantization at zero voltage, the zero-bias conductance only develops a peak (or a local maximum) as a function of voltage for sufficiently large interfacial barrier strength, or certain parameter regimes of spin-orbit coupling strength. Our calculated BTK conductance also shows that the conductance is finite inside the superconducting gap region because of the finite barrier transparency, providing a possible mechanism for the observed ``soft gap'' feature in the experimental studies. Work is done in collaboration with Sankar Das Sarma and supported by Microsoft Q, LPS-CMTC, and JQI-NSF-PFC.

  9. Design principles of interfacial thermal conductance

    NASA Astrophysics Data System (ADS)

    Polanco, Carlos; Rastgarkafshgarkolaei, Rouzbeh; Zhang, Jingjie; Le, Nam; Norris, Pamela; Ghosh, Avik

    We explore fundamental principles to design the thermal conductance across solid interfaces by changing the composition and disorder of an intermediate matching layer. In absence of phonon-phonon interactions, the layer addition involves two competing effects that influence the conductance. The layer can act as an impedance matching 'bridge' to increase the mode-averaged phonon transmission. However, it also reduces the relevant modes that conserve their momenta transverse to the interface, so that the net result depends on features such as the overlap of conserving modes and the dispersivity of the transverse subbands. Moving into the interacting anharmonic regime, we find that the added layer aids conductance when the decreased resistances at the contact-layer boundaries compensate for the layer resistance. In fact, we show that the maximum conductance corresponds to an exact matching of the two separate contact-layer resistances. For instance, if we vary just the atomic mass across layers, then maximum conductance happens when the intervening layer mass is the geometric mean of the contact masses. We conjecture that the best interfacial layer is one that is compositionally graded into many geometric means - in other words, an exponential variation in thermal impedance.

  10. Principles and pitfalls of nerve conduction studies.

    PubMed

    Kimura, J

    1984-10-01

    This report reviews the fundamental principles and the changing concepts of nerve stimulation techniques, and discusses the proper application of these techniques in the differential diagnosis of peripheral nerve disorders. Nerve conduction studies help delineate the extent and distribution of the neural lesion and distinguish two major categories of peripheral nerve disease: demyelination and axonal degeneration. Although the method is based on simple principles, pitfalls abound in practice. Variability in nerve conduction measurement may result from temperature change, variations among nerve segments, and the effects of age. Other sources of error include excessive spread of stimulation current, anomalous innervation, temporal dispersion, and inaccuracy of surface measurement. Unlike a bipolar derivation, which selectively records near-field potentials, a referential recording may give rise to stationary far-field peaks from a moving source. Overlooking this possibility can lead to an incorrect interpretation of findings. Conventional nerve conduction studies deal primarily with measurements of the distal nerve segments in an extremity. More recent techniques are applicable to less accessible anatomical regions, as illustrated by elicitation of the blink reflex, F wave, and H reflex, and the use of the inching technique. Other methods used to assess special aspects of nerve conduction include the ischemic test and studies of slow-conducting fibers. PMID:6093680

  11. Electrically conducting superhydrophobic microtextured carbon nanotube nanocomposite

    NASA Astrophysics Data System (ADS)

    Caffrey, Paul O.; Gupta, Mool C.

    2014-09-01

    We report a simple and inexpensive method of producing an electrically conductive superhydrophobic polymer surface by adding multiwall carbon nanotubes directly into the polymer poly(dimethylsiloxane) (PDMS) matrix and replicating micro/nanotexture using a replication master prepared by ultrafast-laser microtexturing process. No additional coatings on conducting PDMS are required to achieve water contact angles greater than 161°. The conductivity can be controlled by changing the percent MWCNT added to PDMS and at a bulk loading of 4.4 wt% we report a conductivity improvement over pure PDMS by a factor of more than 1011 with electrical resistivity ρ = 761 Ω cm. This combined behavior of a conductive, superhydrophobic nanocomposite has exciting applications for allowing a new class of enclosures providing EMI shielding, water repellency and sensing to provide built-in temperature feedback. The effect of temperature on the nanocomposite was investigated and a negative temperature coefficient of resistance (-0.037 Ω/K) similar to that of a thermistor was observed.

  12. Models of auroral-zone conductances

    NASA Technical Reports Server (NTRS)

    Reiff, P. H.

    1984-01-01

    The magnetosphere-ionosphere system is strongly coupled, with magnetospheric Birkeland currents feeding ionospheric Pedersen and Hall currents. Central to any computer simulation of this system is a detailed, valid conductivity model. An accurate conductivity model is also vital in order to infer Birkeland currents and electric field patterns from inversions of magnetometer chain data. Several recent attempts at constructing conductivity models are presented and their strengths and weaknesses discussed. Incoherent scatter radar measurements can determine height profiles of electron content, from which Pedersen and Hall conductances may be calculated. These yield excellent spatial and good temporal resolution; however, they are limited in field of view. A global pattern requires either 24 hours of data or a chain of stations. Synoptic empirical models (quantized by indices such as Kp or AE) typically are limited by their large bin size (1 deg invariant latitude x 1 hour MLT), and cannot reproduce arcs. Estimating conductivity globally from Dynamics Explorer auroral images is promising, and can yield reasonable time scales (of about 10 minutes); however, this procedure is still only now being tested.

  13. Conductivities of three-layer human skull

    NASA Astrophysics Data System (ADS)

    Akhtari, Massoud

    Electrical conductivities of compact, spongiosum, and bulk layers of the cadaver, live, and dead (corpse) human skull were determined at a number of frequencies and electric fields at room temperature using the four-electrode method. Current was applied and withdrawn over the top and bottom surfaces of each sample and potential drop across different layers was measured. A model that considers variations in skull thicknesses is used to determine the conductivity of the tri-layer skull and its individual anatomical structures. The results indicate that the conductivities of the spongiform (cadaver ˜ 5.4--11.5, live skull ˜ 16.2--41.1, dead ˜ 39.7--99.3 milliS/m), the top compact (cadaver ˜ 0.8--1.8, live ˜ 5.4--7.2, dead ˜ 5.4--12.3 milliS/m) and lower compact (cadaver ˜ 2.8--5.1, live ˜ 2.8--10.2, dead ˜ 5.2--19.3 milliS/m) layers of the skull have significantly different and inhomogeneous conductivities. The conductivities of the skull layers are frequency dependent in the 10--90 Hz region and are non-ohmic in the 0.45--2.07 A/m2 region.

  14. Thermal contact conductance of spherical, rough metals

    SciTech Connect

    Lambert, M.A.; Fletcher, L.S.

    1996-12-31

    Junction thermal conductance is an important consideration in such applications as thermally induced stresses in supersonic and hypersonic flight vehicles, nuclear reactor cooling, electronics packaging, spacecraft thermal control, gas turbine and internal combustion engine cooling, and cryogenic liquid storage. A fundamental problem in analyzing and predicting junction thermal conductance is thermal contact conductance of non-flat, rough metals. Workable models have been previously derived for the limiting idealized cases of flat, rough and spherical, smooth surfaces. However, until now, no tractable models have been advanced for non-flat, rough surfaces (so called engineering surfaces) which are much more commonly dealt with in practice. The present investigation details the synthesis of previously derived models for macroscopically non-uniform thermal contact conductance and contact of non-flat, rough spheres, into a thermo-mechanical model, its refinement, and its presentation in an easily applied format. The present model is compared to representative experimental conductance results form the literature for stainless steel 304 with widely varying flatness deviation and roughness. Also included in the comparisons is a previous, often cited model for flat, rough metals to which the present model reduces in the limit of flat surfaces. The present model agrees well with the experimental results over the wide ranges of flatness deviation and roughness for which data was available. Conversely, the previous, well known model becomes increasingly overpredictive with increasing flatness deviation.

  15. Battery plate containing filler with conductive coating

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor)

    1986-01-01

    The plate (10) comprises a matrix or binder resin phase (12) in which is dispersed particulate, conductive tin oxide such as tin oxide coated glass fibers (14). A monopolar plate (11) is prepared by coating a layer (18) of electrolytically active material onto a surface of the plate (10). Tin oxide is prevented from reduction by coating a surface of the plate (10) with a conductive, impervious layer resistant to reduction such as a thin film (22) of lead adhered to the plate with a layer (21) of conductive adhesive. The plate (10) can be formed by casting a molten dispersion from mixer (36) onto a sheet (30) of lead foil or by passing an assembly of a sheet (41) of resin, a sheet (43) of fiberglass and a sheet (45) of lead between the nip of heated rollers (48, 50).

  16. Battery plate containing filler with conductive coating

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor)

    1985-01-01

    The plate (10) comprises a matrix or binder resin phase (12) in which is dispersed particulate, conductive tin oxide such as tin oxide coated glass fibers (14). A monopolar plate (11) is prepared by coating a layer (18) of electrolytically active material onto a surface of the plate (10). Tin oxide is prevented from reduction by coating a surface of the plate (10) with a conductive, impervious layer resistant to reduction such as a thin film (22) of lead adhered to the plate with a layer (21) of conductive adhesive. The plate (10) can be formed by casting a molten dispersion from mixer (36) onto a sheet (30) of lead foil or by passing an assembly of a sheet (41) of resin, a sheet (43) of fiberglass and a sheet (45) of lead between the nip of heated rollers (48, 50).

  17. Conductance Peaks in Open Quantum Dots

    NASA Astrophysics Data System (ADS)

    Ramos, J. G. G. S.; Bazeia, D.; Hussein, M. S.; Lewenkopf, C. H.

    2011-10-01

    We present a simple measure of the conductance fluctuations in open ballistic chaotic quantum dots, extending the number of maxima method originally proposed for the statistical analysis of compound nuclear reactions. The average number of extreme points (maxima and minima) in the dimensionless conductance T as a function of an arbitrary external parameter Z is directly related to the autocorrelation function of T(Z). The parameter Z can be associated with an applied gate voltage causing shape deformation in quantum dot, an external magnetic field, the Fermi energy, etc. The average density of maxima is found to be ⟨ρZ⟩=αZ/Zc, where αZ is a universal constant and Zc is the conductance autocorrelation length, which is system specific. The analysis of ⟨ρZ⟩ does not require large statistic samples, providing a quite amenable way to access information about parametric correlations, such as Zc.

  18. Magnetic field response sensor for conductive media

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

    2009-01-01

    A magnetic field response sensor comprises an inductor placed at a fixed separation distance from a conductive surface to address the low RF transmissivity of conductive surfaces. The minimum distance for separation is determined by the sensor response. The inductor should be separated from the conductive surface so that the response amplitude exceeds noise level by a recommended 10 dB. An embodiment for closed cavity measurements comprises a capacitor internal to said cavity and an inductor mounted external to the cavity and at a fixed distance from the cavity's wall. An additional embodiment includes a closed cavity configuration wherein multiple sensors and corresponding antenna are positioned inside the cavity, with the antenna and inductors maintained at a fixed distance from the cavity's wall.

  19. Magnetic field response sensor for conductive media

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E. (Inventor); Taylor, Bryant Douglas (Inventor)

    2010-01-01

    A magnetic field response sensor comprises an inductor placed at a fixed separation distance from a conductive surface to address the low RF transmissivity of conductive surfaces. The minimum distance for separation is determined by the sensor response. The inductor should be separated from the conductive surface so that the response amplitude exceeds noise level by a recommended 10 dB. An embodiment for closed cavity measurements comprises a capacitor internal to said cavity and an inductor mounted external to the cavity and at a fixed distance from the cavity's wall. An additional embodiment includes a closed cavity configuration wherein multiple sensors and corresponding antenna are positioned inside the cavity, with the antenna and inductors maintained at a fixed distance from the cavity's wall.

  20. Anisotropic thermal conductivity of semiconducting graphene monoxide

    NASA Astrophysics Data System (ADS)

    Pu, H. H.; Rhim, S. H.; Hirschmugl, C. J.; Gajdardziska-Josifovska, M.; Weinert, M.; Chen, J. H.

    2013-06-01

    The intrinsic thermal conductivity of monolayer graphene monoxide is determined via first-principles calculations. The phonon transport in graphene monoxide is anisotropic, with the lattice thermal conductivity along the armchair direction (…C-2O-C…) about five times higher than that along the zigzag (…C-C…) direction. The predicted thermal conductivity (>3000 Wm-1K-1 at 300 K) of graphene monoxide is 80% of that of graphene along the armchair direction for large sample lateral sizes (>5 μm). In addition, heat is predominantly carried by longitudinal acoustic phonons along the armchair direction, while the contribution from the transverse acoustic phonon mode is prevalent along the zigzag direction.

  1. Conductance through an array of quantum dots

    NASA Astrophysics Data System (ADS)

    Lobos, A. M.; Aligia, A. A.

    2006-10-01

    We propose a simple approach to study the conductance through an array of N interacting quantum dots, weakly coupled to metallic leads. Using a mapping to an effective site which describes the low-lying excitations and a slave-boson representation in the saddle-point approximation, we calculated the conductance through the system. Explicit results are presented for N=1 and N=3 : a linear array and an isosceles triangle. For N=1 in the Kondo limit, the results are in very good agreement with previous results obtained with numerical renormalization group. In the case of the linear trimer for odd N , when the parameters are such that electron-hole symmetry is induced, we obtain perfect conductance G0=2e2/h . The validity of the approach is discussed in detail.

  2. Electrical conductivity in sprite streamer channels

    NASA Astrophysics Data System (ADS)

    Gordillo-Vázquez, F. J.; Luque, A.

    2010-08-01

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

  3. Central auditory conduction time in the rat.

    PubMed

    Shaw, N A

    1990-01-01

    Central conduction time is the time for an afferent volley to traverse the central pathways of a sensory system. In the present study, central auditory conduction time (CACT) was calculated for the rat, the first such formal measurement in any animal. Brainstem auditory evoked potentials (BAEPs) were recorded simultaneously with the primary response of the auditory cortex (P1). The latency of wave II of the BAEP, which arises in the cochlear nucleus, was subtracted from that of P1. This yielded a mean CACT of 6.6 ms. The results confirm a previous theoretical estimate that CACT in the rat is at least twice as long as central somatosensory conduction time. PMID:2311700

  4. Electrochemical characterization of aminated acrylic conducting polymer

    NASA Astrophysics Data System (ADS)

    Rashid, Norma Mohammad; Heng, Lee Yook; Ling, Tan Ling

    2015-09-01

    New attempt has been made to synthesize aminated acrylic conducting polymer (AACP) using precursor of phenylvinylsulfoxide (PVS). The process was conducted via the integration of microemulsion and photopolymerization techniques. It has been utilized for covalent immobilization of amino groups by the adding of N-achryiloxisuccinimide (NAS). Thermal eliminating of benzene sulfenic acids from PVS has been done at 250 °C to form electroactive polyacetylene (PA) segment. Characterization of AACP has been conducted using fourier transform infrared (FTIR), scanning electron microscopy (SEM) and linear sweep cyclic voltammetry (CV). A range of 0.3-1.25μm particle size obtained from SEM characterization. A quasi-reversible system performed as shown in electrochemical study.

  5. Conductivity map from scanning tunneling potentiometry

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Li, Xianqi; Chen, Yunmei; Durand, Corentin; Li, An-Ping; Zhang, X.-G.

    2016-08-01

    We present a novel method for extracting two-dimensional (2D) conductivity profiles from large electrochemical potential datasets acquired by scanning tunneling potentiometry of a 2D conductor. The method consists of a data preprocessing procedure to reduce/eliminate noise and a numerical conductivity reconstruction. The preprocessing procedure employs an inverse consistent image registration method to align the forward and backward scans of the same line for each image line followed by a total variation (TV) based image restoration method to obtain a (nearly) noise-free potential from the aligned scans. The preprocessed potential is then used for numerical conductivity reconstruction, based on a TV model solved by accelerated alternating direction method of multiplier. The method is demonstrated on a measurement of the grain boundary of a monolayer graphene, yielding a nearly 10:1 ratio for the grain boundary resistivity over bulk resistivity.

  6. Effects of anisotropic heat conduction on solidification

    NASA Technical Reports Server (NTRS)

    Weaver, J. A.; Viskanta, R.

    1989-01-01

    Two-dimensional solidification influenced by anisotropic heat conduction has been considered. The interfacial energy balance was derived to account for the heat transfer in one direction (x or y) depending on the temperature gradient in both the x and y directions. A parametric study was made to determine the effects of the Stefan number, aspect ratio, initial superheat, and thermal conductivity ratios on the solidification rate. Because of the imposed boundary conditions, the interface became skewed and sometimes was not a straight line between the interface position at the upper and lower adiabatic walls (spatially nonlinear along the height). This skewness depends on the thermal conductivity ratio k(yy)/k(yx). The nonlinearity of the interface is influenced by the solidification rate, aspect ratio, and k(yy/k(yx).

  7. Gas storage carbon with enhanced thermal conductivity

    DOEpatents

    Burchell, Timothy D.; Rogers, Michael Ray; Judkins, Roddie R.

    2000-01-01

    A carbon fiber carbon matrix hybrid adsorbent monolith with enhanced thermal conductivity for storing and releasing gas through adsorption and desorption is disclosed. The heat of adsorption of the gas species being adsorbed is sufficiently large to cause hybrid monolith heating during adsorption and hybrid monolith cooling during desorption which significantly reduces the storage capacity of the hybrid monolith, or efficiency and economics of a gas separation process. The extent of this phenomenon depends, to a large extent, on the thermal conductivity of the adsorbent hybrid monolith. This invention is a hybrid version of a carbon fiber monolith, which offers significant enhancements to thermal conductivity and potential for improved gas separation and storage systems.

  8. Recent advances in thermal conductivity of nanofluids.

    PubMed

    Witharana, Sanjeeva; Weliwita, Jinendrika Anushi; Chen, Haisheng; Wang, Liang

    2013-11-01

    This paper presents the most recent review of research articles and patents on thermal conductivity on nanofluids. Larger portion of literature accounts for experimental investigations, which is a sign of the preference for hands-on work by experimentalists. Metallic, non-metallic as well as ceramic nanoparticles of different sizes and shapes were suspended in common heat transfer liquids and their thermal conductivities were measured. In contrast to previous belief, it has now been proven that when the nanoparticle concentration is kept low the degree of enhancement falls reasonably within the boundaries predicted by the effective medium theories. There are strong evidences to suggest that the main mechanisms driving the thermal conductivity behavior are nanoparticle aggregation and the particle Brownian motion in suspension. PMID:24330042

  9. 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.

  10. Conductivity map from scanning tunneling potentiometry.

    PubMed

    Zhang, Hao; Li, Xianqi; Chen, Yunmei; Durand, Corentin; Li, An-Ping; Zhang, X-G

    2016-08-01

    We present a novel method for extracting two-dimensional (2D) conductivity profiles from large electrochemical potential datasets acquired by scanning tunneling potentiometry of a 2D conductor. The method consists of a data preprocessing procedure to reduce/eliminate noise and a numerical conductivity reconstruction. The preprocessing procedure employs an inverse consistent image registration method to align the forward and backward scans of the same line for each image line followed by a total variation (TV) based image restoration method to obtain a (nearly) noise-free potential from the aligned scans. The preprocessed potential is then used for numerical conductivity reconstruction, based on a TV model solved by accelerated alternating direction method of multiplier. The method is demonstrated on a measurement of the grain boundary of a monolayer graphene, yielding a nearly 10:1 ratio for the grain boundary resistivity over bulk resistivity. PMID:27587126

  11. Conductive Nanowires Templated by Molecular Brushes.

    PubMed

    Raguzin, Ivan; Stamm, Manfred; Ionov, Leonid

    2015-10-21

    In this paper, we report the fabrication of conductive nanowires using polymer bottle brushes as templates. In our approach, we synthesized poly(2-dimethylamino)ethyl methacrylate methyl iodide quaternary salt brushes by two-step atom transfer radical polymerization, loaded them with palladium salt, and reduced them in order to form metallic nanowires with average lengths and widths of 300 and 20 nm, respectively. The obtained nanowires were deposited between conductive gold pads and were connected to them by sputtering of additional pads to form an electric circuit. We connected the nanowires in an electric circuit and demonstrated that the conductivity of these nanowires is around 100 S·m(-1). PMID:26418290

  12. Interconnecting conductively coated coverslides. [for ISEE-1

    NASA Technical Reports Server (NTRS)

    Gaddy, E. M.; Bass, J. A.

    1978-01-01

    The International Sun Earth Explorer-1 has the requirement that the entire outer surface of the spacecraft be conductive. A transparent coating of indium oxide was deposited for that reason on the satellite's solar cell coverglasses in order to give them a conductive surface, and the surfaces were interconnected to ground. This paper examines the interconnector attachment problem. On the ISEE-1, wires were bonded to the coverglasses by using a conductive epoxy; the resistance of these bonds increased dramatically with time. A program was initiated to find the functional cause of the resistance increase and to flight-qualify an alternative method of bonding. It was found the tests initiated were insufficient to find the cause of resistance increase and that an alternative solution of using indium solder is acceptable for bonding wires directly to indium oxide.

  13. Conductance enlargement in picoscale electroburnt graphene nanojunctions

    PubMed Central

    Sadeghi, Hatef; Mol, Jan A.; Lau, Chit Siong; Briggs, G. Andrew D.; Warner, Jamie; Lambert, Colin J.

    2015-01-01

    Provided the electrical properties of electroburnt graphene junctions can be understood and controlled, they have the potential to underpin the development of a wide range of future sub-10-nm electrical devices. We examine both theoretically and experimentally the electrical conductance of electroburnt graphene junctions at the last stages of nanogap formation. We account for the appearance of a counterintuitive increase in electrical conductance just before the gap forms. This is a manifestation of room-temperature quantum interference and arises from a combination of the semimetallic band structure of graphene and a cross-over from electrodes with multiple-path connectivity to single-path connectivity just before breaking. Therefore, our results suggest that conductance enlargement before junction rupture is a signal of the formation of electroburnt junctions, with a picoscale current path formed from a single sp2 bond. PMID:25730863

  14. THERMAL CONDUCTIVITY OF SIC AND C FIBERS

    SciTech Connect

    Youngblood, Gerald E.; Senor, David J.; Kowbel, W.; Webb, J.; Kohyama, Akira

    2000-09-01

    Several rod-shaped specimens with uniaxially packed fibers (Hi-Nicalon, Hi-Nicalon Type S, Tyranno SA and Amoco K1100 types) and a pre-ceramic polymer matrix have been fabricated. By using appropriate analytic models, the bare fiber thermal conductivity (Kf) and the interface thermal conductance (h) will be determined as a function of temperature up to 1000?C before and after irradiation for samples cut from these rods. Initial results are: (1) for unirradiated Hi-Nicalon SiC fiber, Kf varied from 4.3 up to 5.9 W/mK for the 27-1000?C range, (2) for unirradiated K1100 graphite fiber, Kf varied from 576 down to 242 W/mK for the 27-1000?C range, and (3) h = 43 W/cm2K at 27?C as a typical fiber/matrix interface conductance.

  15. Meteorological radar facility (MRF) slot conductance investigations

    NASA Technical Reports Server (NTRS)

    Ratkevich, A. E.

    1977-01-01

    A preliminary meteorological radar facility (MRF) array design was completed in support of the slot conductance measurement program. Three different slot measurement techniques were evaluated. The selection of the probe comparison measurement technique was selected as the principal experimental method with the impedance measurement technique chosen to measure a few higher conductance slots to be used as reference slots. The impedance of 43 slots in 0.9 x 0.4 inch standard waveguide and of 40 slots in 0.835 x 0.4 inch waveguide was measured. Also, impedance measurements were made of a few slots using image planes to simulate mutual coupling effects. The measured and theoretical conductance, susceptance, and radiation phase data are presented in graphic form as a function of slot displacement for constant slot length, and of slot length for constant slot displacement. It is concluded that the proposed MRF array design approach is a feasible one.

  16. Gas storage carbon with enhanced thermal conductivity

    SciTech Connect

    Burchell, T.D.; Rogers, M.R.; Judkins, R.R.

    2000-07-18

    A carbon fiber carbon matrix hybrid adsorbent monolith with enhanced thermal conductivity for storing and releasing gas through adsorption and desorption is disclosed. The heat of adsorption of the gas species being adsorbed is sufficiently large to cause hybrid monolith heating during adsorption and hybrid monolith cooling during desorption which significantly reduces the storage capacity of the hybrid monolith, or efficiency and economics of a gas separation process. The extent of this phenomenon depends, to a large extent, on the thermal conductivity of the adsorbent hybrid monolith. This invention is a hybrid version of a carbon fiber monolith, which offers significant enhancements to thermal conductivity and potential for improved gas separation and storage systems.

  17. Magnetic Field Response Sensor For Conductive Media

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

    2006-01-01

    A magnetic field response sensor comprises an inductor placed at a fixed separation distance from a conductive surface to address the low RF transmissivity of conductive surfaces. The minimum distance for separation is determined by the sensor response. The inductor should be separated from the conductive surface so that the response amplitude exceeds noise level by a recommended 10 dB. An embodiment for closed cavity measurements comprises a capacitor internal to said cavity and an inductor mounted external to the cavity and at a fixed distance from the cavity s wall. An additional embodiment includes a closed cavity configuration wherein multiple sensors and corresponding antenna are positioned inside the cavity, with the antenna and inductors maintained at a fixed distance from the cavity s wall.

  18. Quantum conductance of zigzag graphene oxide nanoribbons

    SciTech Connect

    Kan, Zhe; Nelson, Christopher; Khatun, Mahfuza

    2014-04-21

    The electronic properties of zigzag graphene oxide nanoribbons (ZGOR) are presented. The results show interesting behaviors which are considerably different from the properties of the perfect graphene nanoribbons (GNRs). The theoretical methods include a Huckel-tight binding approach, a Green's function methodology, and the Landauer formalism. The presence of oxygen on the edge results in band bending, a noticeable change in density of states and thus the conductance. Consequently, the occupation in the valence bands increase for the next neighboring carbon atom in the unit cell. Conductance drops in both the conduction and valence band regions are due to the reduction of allowed k modes resulting from band bending. The asymmetry of the energy band structure of the ZGOR is due to the energy differences of the atoms. The inclusion of a foreign atom's orbital energies changes the dispersion relation of the eigenvalues in energy space. These novel characteristics are important and valuable in the study of quantum transport of GNRs.

  19. Single Molecule Conductance of Oligothiophene Derivatives

    NASA Astrophysics Data System (ADS)

    Dell, Emma J.

    This thesis studies the electronic properties of small organic molecules based on the thiophene motif. If we are to build next-generation devices, advanced materials must be designed which possess requisite electronic functionality. Molecules present attractive candidates for these ad- vanced materials since nanoscale devices are particularly sought after. However, selecting a molecule that is suited to a certain electronic function remains a challenge, and characterization of electronic behavior is therefore critical. Single molecule conductance measurements are a powerful tool to determine properties on the nanoscale and, as such, can be used to investigate novel building blocks that may fulfill the design requirements of next-generation devices. Combining these conductance results with strategic chemical synthesis allows for the development of new families of molecules that show attractive properties for future electronic devices. Since thiophene rings are the fruitflies of organic semiconductors on the bulk scale, they present an intriguing starting point for building functional materials on the nanoscale, and therefore form the structural basis of all molecules studied herein. First, the single-molecule conductance of a family of bithiophene derivatives was measured. A broad distribution in the single-molecule conductance of bithiophene was found compared with that of a biphenyl. This increased breadth in the conductance distribution was shown to be explained by the difference in 5-fold symmetry of thiophene rings as compared to the 6-fold symmetry of benzene rings. The reduced symmetry of thiophene rings results in a restriction on the torsion angle space available to these molecules when bound between two metal electrodes in a junction, causing each molecular junction to sample a different set of conformers in the conductance measurements. By contrast, the rotations of biphenyl are essentially unimpeded by junction binding, allowing each molecular junction

  20. Conducting polymers: Synthesis and industrial applications

    SciTech Connect

    Gottesfeld, S.

    1995-05-01

    The Conducting Polymer project funded by the AIM Materials Program is developing new methods for the synthesis of electronically conducting polymers and is evaluating new industrial applications for these materials which will result in significant reductions in energy usage or industrial waste. The applications specifically addressed during FY 1994 are electrochemical capacitors and membranes for gas separation. As an active material in electrochemical capacitors, conducting polymers have the potential of storing large amounts of electrical energy in low cost materials. Such devices are needed in electronics for power failure back-up and peak power, in power supplies for filtering, and in electric vehicles for peak power and load leveling. As a gas electrically adapt the membrane for specific gas combinations. Potential energy savings in the US. for this application are estimated at 1 to 3 quads/yr.