Dipole excitation of surface plasmon on a conducting sheet: Finite element approximation and validation

NASA Astrophysics Data System (ADS)

Maier, Matthias; Margetis, Dionisios; Luskin, Mitchell

2017-06-01

We formulate and validate a finite element approach to the propagation of a slowly decaying electromagnetic wave, called surface plasmon-polariton, excited along a conducting sheet, e.g., a single-layer graphene sheet, by an electric Hertzian dipole. By using a suitably rescaled form of time-harmonic Maxwell's equations, we derive a variational formulation that enables a direct numerical treatment of the associated class of boundary value problems by appropriate curl-conforming finite elements. The conducting sheet is modeled as an idealized hypersurface with an effective electric conductivity. The requisite weak discontinuity for the tangential magnetic field across the hypersurface can be incorporated naturally into the variational formulation. We carry out numerical simulations for an infinite sheet with constant isotropic conductivity embedded in two spatial dimensions; and validate our numerics against the closed-form exact solution obtained by the Fourier transform in the tangential coordinate. Numerical aspects of our treatment such as an absorbing perfectly matched layer, as well as local refinement and a posteriori error control are discussed.

Spontaneous formation of electric current sheets and the origin of solar flares

NASA Technical Reports Server (NTRS)

Low, B. C.; Wolfson, R.

1988-01-01

It is demonstrated that the continuous boundary motion of a sheared magnetic field in a tenuous plasma with an infinite electrical conductivity can induce the formation of multiple electric current sheets in the interior plasma. In response to specific footpoint displacements, the quadrupolar magnetic field considered is shown to require the formation of multiple electric current sheets as it achieves a force-free state. Some of the current sheets are found to be of finite length, running along separatrix lines of force which separate lobes of magnetic flux. It is suggested that current sheets in the form of infinitely thin magnetic shear layers may be unstable to resistive tearing, a process which may have application to solar flares.

Highly conductive, multi-layer composite precursor composition to fuel cell flow field plate or bipolar plate

DOEpatents

Jang, Bor Z [Centerville, OH; Zhamu, Aruna [Centerville, OH; Guo, Jiusheng [Centerville, OH

2011-02-15

This invention provides a moldable, multiple-layer composite composition, which is a precursor to an electrically conductive composite flow field plate or bipolar plate. In one preferred embodiment, the composition comprises a plurality of conductive sheets and a plurality of mixture layers of a curable resin and conductive fillers, wherein (A) each conductive sheet is attached to at least one resin-filler mixture layer; (B) at least one of the conductive sheets comprises flexible graphite; and (C) at least one resin-filler mixture layer comprises a thermosetting resin and conductive fillers with the fillers being present in a sufficient quantity to render the resulting flow field plate or bipolar plate electrically conductive with a conductivity no less than 100 S/cm and thickness-direction areal conductivity no less than 200 S/cm.sup.2.

Characterization of Hybrid CNT Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Cano, Roberto J.; Kinney, Megan C.; Pressley, James; Sauti, Godfrey; Czabaj, Michael W.; Kim, Jae-Woo; Siochi, Emilie J.

2015-01-01

Carbon nanotubes (CNTs) have been studied extensively since their discovery and demonstrated at the nanoscale superior mechanical, electrical and thermal properties in comparison to micro and macro scale properties of conventional engineering materials. This combination of properties suggests their potential to enhance multi-functionality of composites in regions of primary structures on aerospace vehicles where lightweight materials with improved thermal and electrical conductivity are desirable. In this study, hybrid multifunctional polymer matrix composites were fabricated by interleaving layers of CNT sheets into Hexcel® IM7/8552 prepreg, a well-characterized toughened epoxy carbon fiber reinforced polymer (CFRP) composite. The resin content of these interleaved CNT sheets, as well as ply stacking location were varied to determine the effects on the electrical, thermal, and mechanical performance of the composites. The direct-current electrical conductivity of the hybrid CNT composites was characterized by in-line and Montgomery four-probe methods. For [0](sub 20) laminates containing a single layer of CNT sheet between each ply of IM7/8552, in-plane electrical conductivity of the hybrid laminate increased significantly, while in-plane thermal conductivity increased only slightly in comparison to the control IM7/8552 laminates. Photo-microscopy and short beam shear (SBS) strength tests were used to characterize the consolidation quality of the fabricated laminates. Hybrid panels fabricated without any pretreatment of the CNT sheets resulted in a SBS strength reduction of 70 percent. Aligning the tubes and pre-infusing the CNT sheets with resin significantly improved the SBS strength of the hybrid composite To determine the cause of this performance reduction, Mode I and Mode II fracture toughness of the CNT sheet to CFRP interface was characterized by double cantilever beam (DCB) and end notch flexure (ENF) testing, respectively. Results are compared to the control IM7/8552 laminate.

Electron gun controlled smart structure

DOEpatents

Martin, Jeffrey W.; Main, John Alan; Redmond, James M.; Henson, Tammy D.; Watson, Robert D.

2001-01-01

Disclosed is a method and system for actively controlling the shape of a sheet of electroactive material; the system comprising: one or more electrodes attached to the frontside of the electroactive sheet; a charged particle generator, disposed so as to direct a beam of charged particles (e.g. electrons) onto the electrode; a conductive substrate attached to the backside of the sheet; and a power supply electrically connected to the conductive substrate; whereby the sheet changes its shape in response to an electric field created across the sheet by an accumulation of electric charge within the electrode(s), relative to a potential applied to the conductive substrate. Use of multiple electrodes distributed across on the frontside ensures a uniform distribution of the charge with a single point of e-beam incidence, thereby greatly simplifying the beam scanning algorithm and raster control electronics, and reducing the problems associated with "blooming". By placing a distribution of electrodes over the front surface of a piezoelectric film (or other electroactive material), this arrangement enables improved control over the distribution of surface electric charges (e.g. electrons) by creating uniform (and possibly different) charge distributions within each individual electrode. Removal or deposition of net electric charge can be affected by controlling the secondary electron yield through manipulation of the backside electric potential with the power supply. The system can be used for actively controlling the shape of space-based deployable optics, such as adaptive mirrors and inflatable antennae.

Multifunctional smart composites with integrated carbon nanotube yarn and sheet

NASA Astrophysics Data System (ADS)

Chauhan, Devika; Hou, Guangfeng; Ng, Vianessa; Chaudhary, Sumeet; Paine, Michael; Moinuddin, Khwaja; Rabiee, Massoud; Cahay, Marc; Lalley, Nicholas; Shanov, Vesselin; Mast, David; Liu, Yijun; Yin, Zhangzhang; Song, Yi; Schulz, Mark

2017-04-01

Multifunctional smart composites (MSCs) are materials that combine the good electrical and thermal conductivity, high tensile and shear strength, good impact toughness, and high stiffness properties of metals; the light weight and corrosion resistance properties of composites; and the sensing or actuation properties of smart materials. The basic concept for MSCs was first conceived by Daniel Inman and others about 25 years ago. Current laminated carbon and glass fiber polymeric composite materials have high tensile strength and are light in weight, but they still lack good electrical and thermal conductivity, and they are sensitive to delamination. Carbon nanotube yarn and sheets are lightweight, electrically and thermally conductive materials that can be integrated into laminated composite materials to form MSCs. This paper describes the manufacturing of high quality carbon nanotube yarn and sheet used to form MSCs, and integrating the nanotube yarn and sheet into composites at low volume fractions. Various up and coming technical applications of MSCs are discussed including composite toughening for impact and delamination resistance; structural health monitoring; and structural power conduction. The global carbon nanotube overall market size is estimated to grow from 2 Billion in 2015 to 5 Billion by 2020 at a CAGR of 20%. Nanotube yarn and sheet products are predicted to be used in aircraft, wind machines, automobiles, electric machines, textiles, acoustic attenuators, light absorption, electrical wire, sporting equipment, tires, athletic apparel, thermoelectric devices, biomedical devices, lightweight transformers, and electromagnets. In the future, due to the high maximum current density of nanotube conductors, nanotube electromagnetic devices may also become competitive with traditional smart materials in terms of power density.

Hybrid absorbers composed of Fe3O4 thin film and magnetic composite sheet and enhancement of conduction noise absorption on a microstrip line

NASA Astrophysics Data System (ADS)

Kim, Sung-Soo

2015-05-01

In response to develop wide-band noise absorbers with an improved low-frequency performance, this study investigates hybrid absorbers that are composed of conductive Fe3O4 thin film and magnetic composite sheets. The Fe3O4 films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ωm. Rubber composites with flaky Fe-Si-Al particles of a high permeability and high permittivity are used as the magnetic sheet functioning as an electromagnetic shield barrier. Microstrip lines with a characteristic impedance of 50 Ω are used to measure the noise absorbing properties. For the Fe3O4 film with a low surface resistance and covered by the magnetic sheet, approximately 80% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or Fe3O4 film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the Fe3O4 film through increased electric field strength bounded by the upper magnetic composite sheet. The noise absorption is further enhanced through increasing the electrical conductivity of the film containing more conductive phase (Fe3O4 + Fe), which can be prepared in a reduced oxygen partial pressure during reactive sputtering.

Study of GO-Cu2O and RGO-Cu nanocomposite monolayer sheets prepared by modified Langmuir Blodgett route

NASA Astrophysics Data System (ADS)

Botcha, V. Divakar; Sutar, D. S.; Major, S. S.

2018-07-01

The modified Langmuir-Blodgett (MLB) technique has been improvised and extended to transfer GO-Cu2O nanocomposite monolayer sheets, by introducing Cu2+ ions into the subphase at room temperature. Morphological studies of as-transferred sheets revealed the presence of closely spaced GO monolayer sheets, with slightly enhanced roughness. XPS studies of as-transferred sheets confirmed the presence of copper, either as metallic Cu or Cu2O, along with significant Cu(OH)2 component, but TEM results confirmed the formation of Cu2O nanocrystallites of size (7 ± 2) nm, distributed uniformly over GO sheets. After heat treatment in vacuum at 400 °C, the nanocomposite sheets were covered with a uniform distribution of larger size nanoparticles. Based on Raman, XPS and TEM studies it has been confirmed that heat treatment at 400 °C in vacuum results in the formation of agglomerated Cu nanoparticles of size (23 ± 9) nm distributed uniformly over reduced graphene oxide (RGO) sheets. The electrical characterization of nanocomposite sheets on SiO2/Si in back-gated FET geometry revealed that the electrical conductivity of as-transferred GO-Cu2O sheets was similar to that usually observed for GO monolayer sheets. The RGO-Cu sheets also displayed electrical conductivity and field effect mobility values comparable to those reported for RGO sheets obtained by chemical/thermal reduction, and was unaffected by the presence of Cu nanoparticles.

Enhancement of conduction noise absorption by hybrid absorbers composed of indium-tin-oxide thin film and magnetic composite sheet on a microstrip line

NASA Astrophysics Data System (ADS)

Kim, Sun-Hong; Kim, Sung-Soo

2014-05-01

In order to develop wide-band noise absorbers with a focused design for low frequency performance, this study investigates hybrid absorbers that are composed of conductive indium-tin-oxide (ITO) thin film and magnetic composite sheets. The ITO films prepared via reactive sputtering exhibit a typical value of electrical resistivity of ≃10-4 Ω m. Rubber composites with flaky Fe-Si-Al particles are used as the magnetic sheet with a high permeability and high permittivity. For the ITO film with a low surface resistance and covered by the magnetic sheet, approximately 90% power absorption can be obtained at 1 GHz, which is significantly higher than that of the original magnetic sheet or ITO film. The high power absorption of the hybrid absorber is attributed to the enhanced ohmic loss of the ITO film through increased electric field strength bounded by the upper magnetic composite sheet. However, for the reverse layering sequence of the ITO film, the electric field experienced by ITO film is very weak due to the electromagnetic shielding by the under layer of magnetic sheet, which does not result in enhanced power absorption.

Tunable electrical conductivity of individual graphene oxide sheets reduced at "low" temperatures.

PubMed

Jung, Inhwa; Dikin, Dmitriy A; Piner, Richard D; Ruoff, Rodney S

2008-12-01

Step-by-step controllable thermal reduction of individual graphene oxide sheets, incorporated into multiterminal field effect devices, was carried out at low temperatures (125-240 degrees C) with simultaneous electrical measurements. Symmetric hysteresis-free ambipolar (electron- and hole-type) gate dependences were observed as soon as the first measurable resistance was reached. The conductivity of each of the fabricated devices depended on the level of reduction (was increased more than 10(6) times as reduction progressed), strength of the external electrical field, density of the transport current, and temperature.

Electromagnetic augmentation for casting of thin metal sheets

DOEpatents

Hull, J.R.

1987-10-28

Thin metal sheets are cast by magnetically levitating molten metal deposited in a model within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled by the water-cooled walls of the mold to form a solid metal sheet. A conducting shield is electrically coupled to the molten metal sheet to provide a return path for eddy currents induced in the metal sheet by the current in the AC conducting coils. In another embodiment, a DC conducting coil is coupled to the metal sheet for providing a direct current therein which interacts with the magnetic field to levitate the moving metal sheet. Levitation of the metal sheet in both molten and solid forms reduces its contact pressure with the mold walls while maintaining sufficient engagement therebetween to permit efficient conductive cooling by the mold through which a coolant fluid may be circulated. 8 figs.

Simulating the interplay between plasma transport, electric field, and magnetic field in the near-earth nightside magnetosphere

NASA Astrophysics Data System (ADS)

Gkioulidou, Malamati

The convection electric field resulting from the coupling of the Earth's magnetosphere with the solar wind and interplanetary magnetic field (IMF) drives plasma in the tail plasma sheet earthward. This transport and the resulting energy storage in the near Earth plasma sheet are important for setting up the conditions that lead to major space weather disturbances, such as storms and substorms. Penetration of plasma sheet particles into the near-Earth magnetosphere in response to enhanced convection is crucial to the development of the Region 2 field-aligned current system and large-scale magnetosphere-ionosphere (M-I) coupling, which results in the shielding of the convection electric field. In addition to the electric field, plasma transport is also strongly affected by the magnetic field, which is distinctly different from dipole field in the inner plasma sheet and changes with plasma pressure in maintaining force balance. The goal of this dissertation is to investigate how the plasma transport into the inner magnetosphere is affected by the interplay between plasma, electric field and magnetic field. For this purpose, we conduct simulations using the Rice Convection Model (RCM), which self-consistently calculates the electric field resulting from M-I coupling. In order to quantitatively evaluate the interplay, we improved the RCM simulations by establishing realistic plasma sheet particle sources, by incorporating it with a modified Dungey force balance magnetic field solver (RCM-Dungey runs), and by adopting more realistic electron loss rates. We found that plasma sheet particle sources strongly affect the shielding of the convection electric field, with a hotter and more tenuous plasma sheet resulting in less shielding than a colder and denser one and thus in more earthward penetration of the plasma sheet. The Harang reversal, which is closely associated with the shielding of the convection electric field and the earthward penetration of low-energy protons, is found to be located at lower latitudes and extend more dawnward for a hotter and more tenuous plasma sheet. In comparison with simulation runs under an empirical but not force balance magnetic field from the Tsyganenko 96 model, the simulation results show that transport under force-balanced magnetic field results in weaker pressure gradients and thus weaker R2 FAC in the near-earth region, weaker shielding of the penetration electric field and, as a result, more earthward penetration of plasma sheet protons and electrons with their inner edges being closer together and more azimuthally symmetric. To evaluate the effect of electron loss rate on ionospheric conductivity, a major contributing factor to M-I coupling, we run RCM-Dungey with a more realistic, MLT dependent electron loss rate established from observed wave activity. Comparing our results with those using a strong diffusion everywhere rate, we found that under the MLT dependent loss rate, the dawn-dusk asymmetry in the precipitating electron energy fluxes agrees better with statistical DMSP observations. The more realistic loss rate is much weaker than the strong diffusion limit in the inner magnetosphere. This allows high-energy electrons in the inner magnetosphere to remain much longer and produce substantial conductivity at lower latitudes. The higher conductivity at lower latitudes under the MLT dependent loss rate results in less efficient shielding in response to an enhanced convection electric field, and thus to deeper penetration of the ion plasma sheet into the inner magnetosphere than under the strong diffusion everywhere rate.

Electrical Conductivity in Transparent Silver Nanowire Networks: Simulations and Experiments

NASA Astrophysics Data System (ADS)

Sherrott, Michelle; Mutiso, Rose; Rathmell, Aaron; Wiley, Benjamin; Winey, Karen

2012-02-01

We model and experimentally measure the electrical conductivity of two-dimensional networks containing finite, conductive cylinders with aspect ratio ranging from 33 to 333. We have previously used our simulations to explore the effects of cylinder orientation and aspect ratio in three-dimensional composites, and now extend the simulation to consider two-dimensional silver nanowire networks. Preliminary results suggest that increasing the aspect ratio and area fraction of these rods significantly decreases the sheet resistance of the film. For all simulated aspect ratios, this sheet resistance approaches a constant value for high area fractions of rods. This implies that regardless of aspect ratio, there is a limiting minimum sheet resistance that is characteristic of the properties of the nanowires. Experimental data from silver nanowire networks will be incorporated into the simulations to define the contact resistance and corroborate experimentally measured sheet resistances of transparent thin films.

A comprehensive study of the electrically conducting water based CuO and Al2O3 nanoparticles over coupled nanofluid-sheet interface

NASA Astrophysics Data System (ADS)

Ahmad, R.

2016-02-01

Many studies on nanofluid flow over a permeable/impermeable sheet prescribe the kinematics of the sheet and disregard the sheet’s mechanics. However, the current study is one of the infrequent contributions that anticipate the mechanics of both the electrically conducting nanofluid (a homogeneous mixture of nanoparticles and base fluid) and the sheet. Two types of nanoparticles, alumina and copper, with water as a base fluid over the sheet are considered. With the help of the similarity transformations, the corresponding partial differential equations for the coupled nanofluid-sheet interface are transformed into a system of ordinary differential equations. The simulations are done by using the experimentally verified results from the previous studies for viscosity and thermal conductivity. Self-similar solutions are attained by considering both analytical and numerical techniques. Dual skin friction coefficients are attained with different copper and alumina nanoparticles over both the stretching and viscous sheets. The influence of the Eckert number, magnetic and mass suction/blowing parameters on the dimensionless velocity, temperature, skin friction and heat transfer rates over the nanofluid-sheet interface are presented graphically as well as numerically. The obtained results are of potential benefit for studying nanofluid flow over various soft surfaces such as synthetic plastics, soft silicone sheet and soft synthetic rubber sheet. These surfaces are easily deformed by thermal fluctuations.

Bipolar fuel cell

DOEpatents

McElroy, James F.

1989-01-01

The present invention discloses an improved fuel cell utilizing an ion transporting membrane having a catalytic anode and a catalytic cathode bonded to opposite sides of the membrane, a wet-proofed carbon sheet in contact with the cathode surface opposite that bonded to the membrane and a bipolar separator positioned in electrical contact with the carbon sheet and the anode of the adjacent fuel cell. Said bipolar separator and carbon sheet forming an oxidant flowpath, wherein the improvement comprises an electrically conductive screen between and in contact with the wet-proofed carbon sheet and the bipolar separator improving the product water removal system of the fuel cell.

Electrospun conductive nanofibrous scaffolds for engineering cardiac tissue and 3D bioactuators.

PubMed

Wang, Ling; Wu, Yaobin; Hu, Tianli; Guo, Baolin; Ma, Peter X

2017-09-01

Mimicking the nanofibrous structure similar to extracellular matrix and conductivity for electrical propagation of native myocardium would be highly beneficial for cardiac tissue engineering and cardiomyocytes-based bioactuators. Herein, we developed conductive nanofibrous sheets with electrical conductivity and nanofibrous structure composed of poly(l-lactic acid) (PLA) blending with polyaniline (PANI) for cardiac tissue engineering and cardiomyocytes-based 3D bioactuators. Incorporating of varying contents of PANI from 0wt% to 3wt% into the PLA polymer, the electrospun nanofibrous sheets showed enhanced conductivity while maintaining the same fiber diameter. These PLA/PANI conductive nanofibrous sheets exhibited good cell viability and promoting effect on differentiation of H9c2 cardiomyoblasts in terms of maturation index and fusion index. Moreover, PLA/PANI nanofibrous sheets enhanced the cell-cell interaction, maturation and spontaneous beating of primary cardiomyocytes. Furthermore, the cardiomyocytes-laden PLA/PANI conductive nanofibrous sheets can form 3D bioactuators with tubular and folding shapes, and spontaneously beat with much higher frequency and displacement than that on cardiomyocytes-laden PLA nanofibrous sheets. Therefore, these PLA/PANI conductive nanofibrous sheets with conductivity and extracellular matrix like nanostructure demonstrated promising potential in cardiac tissue engineering and cardiomyocytes-based 3D bioactuators. Cardiomyocytes-based bioactuators have been paid more attention due to their spontaneous motion by integrating cardiomyocytes into polymer structures, but developing suitable scaffolds for bioactuators remains challenging. Electrospun nanofibrous scaffolds have been widely used in cardiac tissue engineering because they can mimic the extracellular matrix of myocardium. Developing conductive nanofibrous scaffolds by electrospinning would be beneficial for cardiomyocytes-based bioactuators, but such scaffolds have been rarely reported. This work presented a conductive nanofibrous sheet based on polylactide and polyaniline via electrospinning with tunable conductivity. These conductive nanofibrous sheets performed the ability to enhance cardiomyocytes maturation and spontaneous beating, and further formed cardiomyocytes-based 3D bioactuators with tubular and folding shapes, which indicated their great potential in cardiac tissue engineering and bioactuators applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The performance of fast-moving low-voltage electromechanical actuators based on single-walled carbon nanotubes and ionic liquids

NASA Astrophysics Data System (ADS)

Mukai, Ken; Asaka, Kinji; Hata, Kenji; Oike, Hideaki

2011-12-01

In this paper, we study the details of the mechanical and electrical properties of polymer-free single-walled carbon nanotube (SWNT) sheets containing different contents of ionic liquids (ILs). The polymer-free SWNT sheets were prepared by a previously reported finding that millimeter-long 'super-growth' carbon nanotubes (SG-SWNTs), produced by a water-assisted modified chemical vapor deposition (CVD) method, associate together tightly with ILs, affording a free-standing sheet with a superb conductivity. The Young's modulus, breaking strength and the electrical conductivity of the SG-SWNT sheet with 67 wt% 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) showed large values, 0.63 GPa, 20 MPa, and 147 S cm-1, respectively, although it has large amounts of ILs. We also measure the frequency dependence of the displacement of the actuator composed of SG-SWNT sheets sandwiching an ionic-gel electrolyte layer (SG-SWNT actuator). At more than 50 wt% of EMITFSI content, the frequency response of the actuation of the SG-SWNT actuator is flat up to around 100 Hz. The results of the displacement measurements are discussed in relation to the mechanical and electrical properties of the SG-SWNT actuators.

Linear instabilities of a planar liquid sheet in a static electric field for intermediate relaxation and convection of surface charges

NASA Astrophysics Data System (ADS)

Yoshinaga, Takao

2018-04-01

Linear temporal instabilities of a two-dimensional planar liquid sheet in a static electric field are investigated when the relaxation and convection of surface electric charges are considered. Both viscous sheet liquid and inviscid surrounding liquid are placed between two parallel sheath walls, on which an external electric field is imposed. In particular, effects of the electric Peclet number {Pe} (charge relaxation time/convection time) and the electric Euler number Λ (electric pressure/liquid inertial) on the instabilities are emphasized for the symmetric and antisymmetric deformations of the sheet. It is found that the unstable mode is composed of the aerodynamic and electric modes, which are merged with each other for the symmetric deformation and separated for the antisymmetric deformation. For the symmetric deformation, the combined mode is more destabilized with the decrease of {Pe} and the increase of Λ. On the other hand, for the antisymmetric deformation, the electric mode is more destabilized and the aerodynamic mode is left unchanged with the decrease of {Pe}, while the electric mode is more destabilized but the aerodynamic mode is more stabilized with the increase of Λ. It is also found for both symmetric and antisymmetric deformations that the instabilities are most suppressed when {σ }R≃ 1/{ε }P ({σ }R: conductivity ratio of the surrounding to the sheet liquid, {ε }P: permittivity ratio of the sheet to the surrounding liquid), whose trend of the instabilities is more enhanced with the decrease of {Pe} except for vanishingly small {Pe}.

Superior Electrical Contractors Inc. Information Sheet

EPA Pesticide Factsheets

Superior Electrical Contractors Inc. (the Company) is located in Boise, Idaho. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Boise, Idaho.

Graphene-silica composite thin films as transparent conductors.

PubMed

Watcharotone, Supinda; Dikin, Dmitriy A; Stankovich, Sasha; Piner, Richard; Jung, Inhwa; Dommett, Geoffrey H B; Evmenenko, Guennadi; Wu, Shang-En; Chen, Shu-Fang; Liu, Chuan-Pu; Nguyen, SonBinh T; Ruoff, Rodney S

2007-07-01

Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.

Graphene-silica Composite Thin Films as Transparent Conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watcharotone,S.; Dikin, D.; Stankovich, S.

2007-01-01

Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiO{sub x}/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.

Method of Fabricating a Piezoelectric Composite Apparatus

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats (Inventor); Bryant, Robert (Inventor); Fox, Robert L. (Inventor); Hellbaum, Richard F. (Inventor); High, James W. (Inventor); Jalink, Antony, Jr. (Inventor); Little, Bruce D. (Inventor); Mirick, Paul H. (Inventor)

2003-01-01

A method for fabricating a piezoelectric macro-fiber composite actuator comprises providing a piezoelectric material that has two sides and attaching one side upon an adhesive backing sheet. The method further comprises slicing the piezoelectric material to provide a plurality of piezoelectric fibers in juxtaposition. A conductive film is then adhesively bonded to the other side of the piezoelectric material, and the adhesive backing sheet is removed. The conductive film has first and second conductive patterns formed thereon which are electrically isolated from one another and in electrical contact with the piezoelectric material. The first and second conductive patterns of the conductive film each have a plurality of electrodes to form a pattern of interdigitated electrodes. A second film is then bonded to the other side of the piezoelectric material. The second film may have a pair of conductive patterns similar to the conductive patterns of the first film.

Electromagnetic augmentation for casting of thin metal sheets

DOEpatents

Hull, John R.

1989-01-01

Thin metal sheets are cast by magnetically levitating molten metal deposited in a mold within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled by the water-cooled walls of the mold to form a solid metal sheet. A conducting shield is electrically coupled to the molten metal sheet to provide a return path for eddy currents induced in the metal sheet by the current in the AC conducting coils. In another embodiment, a DC conducting coil is coupled to the metal sheet for providing a direct current therein which interacts with the magnetic field to levitate the moving metal sheet. Levitation of the metal sheet in both molten and solid forms reduces its contact pressure with the mold walls while maintaining sufficient engagement therebetween to permit efficient conductive cooling by the mold through which a coolant fluid may be circulated. The magnetic fields associated with the currents in the aforementioned coils levitate the molten metal sheet while the mold provides for its lateral and vertical confinement. A leader sheet having electromagnetic characteristics similar to those of the molten metal sheet is used to start the casing process and precedes the molten metal sheet through the yoke/coil arrangement and mold and forms a continuous sheet therewith. The yoke/coil arrangement may be either U-shaped with a single racetrack coil or may be rectangular with a pair of spaced, facing bedstead coils.

Horizontal electromagnetic casting of thin metal sheets

DOEpatents

Hull, John R.; Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

1987-01-01

Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

Horizontal electromagnetic casting of thin metal sheets

DOEpatents

Hull, John R.; Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

1988-01-01

Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

High conductivity carbon nanotube wires from radial densification and ionic doping

NASA Astrophysics Data System (ADS)

Alvarenga, Jack; Jarosz, Paul R.; Schauerman, Chris M.; Moses, Brian T.; Landi, Brian J.; Cress, Cory D.; Raffaelle, Ryne P.

2010-11-01

Application of drawing dies to radially densify sheets of carbon nanotubes (CNTs) into bulk wires has shown the ability to control electrical conductivity and wire density. Simultaneous use of KAuBr4 doping solution, during wire drawing, has led to an electrical conductivity in the CNT wire of 1.3×106 S/m. Temperature-dependent electrical measurements show that conduction is dominated by fluctuation-assisted tunneling, and introduction of KAuBr4 significantly reduces the tunneling barrier between individual nanotubes. Ultimately, the concomitant doping and densification process leads to closer packed CNTs and a reduced charge transfer barrier, resulting in enhanced bulk electrical conductivity.

Magnesium-based methods, systems, and devices

DOEpatents

Zhao, Yufeng; Ban, Chunmei; Ruddy, Daniel; Parilla, Philip A.; Son, Seoung-Bum

2017-12-12

An aspect of the present invention is an electrical device, where the device includes a current collector and a porous active layer electrically connected to the current collector to form an electrode. The porous active layer includes MgB.sub.x particles, where x.gtoreq.1, mixed with a conductive additive and a binder additive to form empty interstitial spaces between the MgB.sub.x particles, the conductive additive, and the binder additive. The MgB.sub.x particles include a plurality of boron sheets of boron atoms covalently bound together, with a plurality of magnesium atoms reversibly intercalated between the boron sheets and ionically bound to the boron atoms.

Electrode for electrochemical cell

DOEpatents

Kaun, T.D.; Nelson, P.A.; Miller, W.E.

1980-05-09

An electrode structure for a secondary electrochemical cell includes an outer enclosure defining a compartment containing electrochemical active material. The enclosure includes a rigid electrically conductive metal sheet with perforated openings over major side surfaces. The enclosure can be assembled as first and second trays each with a rigid sheet of perforated electrically conductive metal at major side surfaces and normally extending flanges at parametric margins. The trays can be pressed together with moldable active material between the two to form an expandable electrode. A plurality of positive and negative electrodes thus formed are arranged in an alternating array with porous frangible interelectrode separators within the housing of the secondary electrochemical cell.

Electrode for electrochemical cell

DOEpatents

Kaun, Thomas D.; Nelson, Paul A.; Miller, William E.

1981-01-01

An electrode structure for a secondary electrochemical cell includes an outer enclosure defining a compartment containing electrochemical active material. The enclosure includes a rigid electrically conductive metal sheet with perforated openings over major side surfaces. The enclosure can be assembled as first and second trays each with a rigid sheet of perforated electrically conductive metal at major side surfaces and normally extending flanges at parametric margins. The trays can be pressed together with moldable active material between the two to form an expandable electrode. A plurality of positive and negative electrodes thus formed are arranged in an alternating array with porous frangible interelectrode separators within the housing of the secondary electrochemical cell.

In vivo feasibility test using transparent carbon nanotube-coated polydimethylsiloxane sheet at brain tissue and sciatic nerve.

PubMed

Wang, Caifeng; Oh, Sangjin; Lee, Hyun Ah; Kang, Jieun; Jeong, Ki-Jae; Kang, Seon Woo; Hwang, Dae Youn; Lee, Jaebeom

2017-06-01

Carbon nanotubes, with their unique and outstanding properties, such as strong mechanical strength and high electrical conductivity, have become very popular for the repair of tissues, particularly for those requiring electrical stimuli. Polydimethylsiloxane (PDMS)-based elastomers have been used in a wide range of biomedical applications because of their optical transparency, physiological inertness, blood compatibility, non-toxicity, and gas permeability. In present study, most of artificial nerve guidance conduits (ANGCs) are not transparent. It is hard to confirm the position of two stumps of damaged nerve during nerve surgery and the conduits must be cut open again to observe regenerative nerves after surgery. Thus, a novel preparation method was utilized to produce a transparent sheet using PDMS and multiwalled carbon nanotubes (MWNTs) via printing transfer method. Characterization of the PDMS/MWNT (PM) sheets revealed their unique physicochemical properties, such as superior mechanical strength, a certain degree of electrical conductivity, and high transparency. Characterization of the in vitro and in vivo usability was evaluated. PM sheets showed high biocompatibility and adhesive ability. In vivo feasibility tests of rat brain tissue and sciatic nerve revealed the high transparency of PM sheets, suggesting that it can be used in the further development of ANGCs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1736-1745, 2017. © 2017 Wiley Periodicals, Inc.

40 CFR 60.52Da - Recordkeeping requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Electric Utility... opacity field data sheets; (2) For each performance test conducted using Method 22 of appendix A-4 of this... performance test; (iii) Copies of all visible emission observer opacity field data sheets; and (iv...

Microwave conductance properties of aligned multiwall carbon nanotube textile sheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Brian L.; Martinez, Patricia; Zakhidov, Anvar A.

2015-07-06

Understanding the conductance properties of multi-walled carbon nanotube (MWNT) textile sheets in the microwave regime is essential for their potential use in high-speed and high-frequency applications. To expand current knowledge, complex high-frequency conductance measurements from 0.01 to 50 GHz and across temperatures from 4.2 K to 300 K and magnetic fields up to 2 T were made on textile sheets of highly aligned MWNTs with strand alignment oriented both parallel and perpendicular to the microwave electric field polarization. Sheets were drawn from 329 and 520 μm high MWNT forests that resulted in different DC resistance anisotropy. For all samples, themore » microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. Finally, this is consistent with diffusive Drude conduction as the primary transport mechanism up to 50 GHz. Further, it is found that the microwave conductance is essentially independent of both temperature and magnetic field.« less

Experimental investigation into the coupling effects of magnetic field, temperature and pressure on electrical resistivity of non-oriented silicon steel sheet

NASA Astrophysics Data System (ADS)

Xiao, Lijun; Yu, Guodong; Zou, Jibin; Xu, Yongxiang

2018-05-01

In order to analyze the performance of magnetic device which operate at high temperature and high pressure, such as submersible motor, oil well transformer, the electrical resistivity of non-oriented silicon steel sheets is necessary for precise analysis. But the reports of the examination of the measuring method suitable for high temperature up to 180 °C and high pressure up to 140 MPa are few. In this paper, a measurement system based on four-probe method and Archimedes spiral shape measurement specimens is proposed. The measurement system is suitable for measuring the electrical resistivity of unconventional specimens under high temperature and high pressure and can simultaneously consider the influence of the magnetic field on the electrical resistivity. It can be seen that the electrical resistivity of the non-oriented silicon steel sheets will fluctuate instantaneously when the magnetic field perpendicular to the conductive path of the specimens is loaded or removed. The amplitude and direction of the fluctuation are not constant. Without considering the effects of fluctuations, the electrical resistivity of the non-oriented silicon steel sheets is the same when the magnetic field is loaded or removed. And the influence of temperature on the electrical resistivity of the non-oriented silicon steel sheet is still the greatest even though the temperature and the pressure are coupled together. The measurement results also show that the electrical resistivity varies linearly with temperature, so the temperature coefficient of resistivity is given in the paper.

Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

DOEpatents

Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleishhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

2003-12-09

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Thermomechanical processing of plasma sprayed intermetallic sheets

DOEpatents

Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

2001-01-01

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

DOEpatents

Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

2000-01-01

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr.ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Resistivity changes in conductive silicone sheets under stretching.

PubMed

González-Correa, C A; Screaton, G; Hose, D R; Brown, B H; Avis, N J; Kleinermann, F

2002-02-01

This paper reports a preliminary finding associated with an investigation of how tissues respond to mechanical stress. The stress distribution within the tissue may be the result of normal function, for example, joint forces, or it may result from interventions such as tissue suturing during or after surgery. We sought to combine electrical and mechanical computational models in order to better understand the interaction between the two. For example, if mechanical stress is applied to tissue this may change the cell arrangements within the tissue matrix and hence change the electrical properties. If this interaction could be determined, then it should be possible to use electrical impedance tomography measurements to identify stress patterns in tissues. Measurements of resistivity changes have been made in conductive silicone rubber sheets when subject to a uniaxial stress of up to 10%. Relatively large changes in resistivity are produced (up to 200%). These changes are far larger than those predicted arising from topological changes alone. It is suggested that under stress the conductive islands of carbon within the silicone rubber sheet undergo a reversible disassociation from their neighbours and that the material's electrical properties change under load. If similar stress-resistivity relationships occur within biological materials it may be possible to recover the stress fields within tissues from transfer impedance measurements and thereby predict if actions such as inappropriate suture tension will compromise tissue viability.

Graphene-based composite materials.

PubMed

Stankovich, Sasha; Dikin, Dmitriy A; Dommett, Geoffrey H B; Kohlhaas, Kevin M; Zimney, Eric J; Stach, Eric A; Piner, Richard D; Nguyen, SonBinh T; Ruoff, Rodney S

2006-07-20

Graphene sheets--one-atom-thick two-dimensional layers of sp2-bonded carbon--are predicted to have a range of unusual properties. Their thermal conductivity and mechanical stiffness may rival the remarkable in-plane values for graphite (approximately 3,000 W m(-1) K(-1) and 1,060 GPa, respectively); their fracture strength should be comparable to that of carbon nanotubes for similar types of defects; and recent studies have shown that individual graphene sheets have extraordinary electronic transport properties. One possible route to harnessing these properties for applications would be to incorporate graphene sheets in a composite material. The manufacturing of such composites requires not only that graphene sheets be produced on a sufficient scale but that they also be incorporated, and homogeneously distributed, into various matrices. Graphite, inexpensive and available in large quantity, unfortunately does not readily exfoliate to yield individual graphene sheets. Here we present a general approach for the preparation of graphene-polymer composites via complete exfoliation of graphite and molecular-level dispersion of individual, chemically modified graphene sheets within polymer hosts. A polystyrene-graphene composite formed by this route exhibits a percolation threshold of approximately 0.1 volume per cent for room-temperature electrical conductivity, the lowest reported value for any carbon-based composite except for those involving carbon nanotubes; at only 1 volume per cent, this composite has a conductivity of approximately 0.1 S m(-1), sufficient for many electrical applications. Our bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications.

Highly thermally conductive and mechanically strong graphene fibers.

PubMed

Xin, Guoqing; Yao, Tiankai; Sun, Hongtao; Scott, Spencer Michael; Shao, Dali; Wang, Gongkai; Lian, Jie

2015-09-04

Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is the thinnest, strongest, and stiffest known material and an excellent conductor of heat and electricity. However, these superior properties have yet to be realized for graphene-derived macroscopic structures such as graphene fibers. We report the fabrication of graphene fibers with high thermal and electrical conductivity and enhanced mechanical strength. The inner fiber structure consists of large-sized graphene sheets forming a highly ordered arrangement intercalated with small-sized graphene sheets filling the space and microvoids. The graphene fibers exhibit a submicrometer crystallite domain size through high-temperature treatment, achieving an enhanced thermal conductivity up to 1290 watts per meter per kelvin. The tensile strength of the graphene fiber reaches 1080 megapascals. Copyright © 2015, American Association for the Advancement of Science.

Polymer quenched prealloyed metal powder

DOEpatents

Hajaligol, Mohammad R.; Fleischhauer, Grier; German, Randall M.

2001-01-01

A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3 % Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

Microscopic vertical orientation of nano-interspaced graphene architectures in deposit films as electrodes for enhanced supercapacitor performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Gyoung Gug; Song, Bo; Li, Liyi

This paper reported a novel two-step process to fabricate high-performance supercapacitor films that contain microscale domains of nano-interspaced, re-stacked graphene sheets oriented perpendicular to the surface of current collector substrate, i.e., carbon fiber paper. In the two-step process, we first used ligand molecules to modify the surface of graphene oxide (GO) sheets and manipulate the interspacing between the re-stacked GO sheets. The ligand-modified GOs, i.e., m-GOs, were then reduced to obtain more conductive graphene (m-rGO), where X-ray diffraction measurement results indicated well-controlled interlayer spacing between the restacked m-rGO sheets up to 1 nm. The typical lateral dimension of the restackedmore » m-rGO sheets were ~40 µm. Then, electrical field was introduced during m-rGO slurry deposition process to induce the vertical orientation of the m-rGO sheets/stacks in the film deposit. The direct current electrical field induced the orientation of the domains of m-rGO stacks along the direction perpendicular to the surface of deposit film, i.e., direction of electric field. Also, the applied electric field increased the interlayer spacing further, which should enhance the diffusion and accessibility of electrolyte ions. As compared with the traditionally deposited “control” films, the field-processed film deposits that contain oriented structure of graphene sheets/stacks have shown up to ~1.6 times higher values in capacitance (430 F/g at 0.5 A/g) and ~67% reduction in equivalent series resistance. Finally, the approach of using electric field to tailor the microscopic architecture of graphene-based deposit films is effective to fabricate film electrodes for high performance supercapacitors.« less

Microscopic vertical orientation of nano-interspaced graphene architectures in deposit films as electrodes for enhanced supercapacitor performance

DOE PAGES

Jang, Gyoung Gug; Song, Bo; Li, Liyi; ...

2016-12-14

This paper reported a novel two-step process to fabricate high-performance supercapacitor films that contain microscale domains of nano-interspaced, re-stacked graphene sheets oriented perpendicular to the surface of current collector substrate, i.e., carbon fiber paper. In the two-step process, we first used ligand molecules to modify the surface of graphene oxide (GO) sheets and manipulate the interspacing between the re-stacked GO sheets. The ligand-modified GOs, i.e., m-GOs, were then reduced to obtain more conductive graphene (m-rGO), where X-ray diffraction measurement results indicated well-controlled interlayer spacing between the restacked m-rGO sheets up to 1 nm. The typical lateral dimension of the restackedmore » m-rGO sheets were ~40 µm. Then, electrical field was introduced during m-rGO slurry deposition process to induce the vertical orientation of the m-rGO sheets/stacks in the film deposit. The direct current electrical field induced the orientation of the domains of m-rGO stacks along the direction perpendicular to the surface of deposit film, i.e., direction of electric field. Also, the applied electric field increased the interlayer spacing further, which should enhance the diffusion and accessibility of electrolyte ions. As compared with the traditionally deposited “control” films, the field-processed film deposits that contain oriented structure of graphene sheets/stacks have shown up to ~1.6 times higher values in capacitance (430 F/g at 0.5 A/g) and ~67% reduction in equivalent series resistance. Finally, the approach of using electric field to tailor the microscopic architecture of graphene-based deposit films is effective to fabricate film electrodes for high performance supercapacitors.« less

A new architecture as transparent electrodes for solar and IR applications based on photonic structures via soft lithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuang, Ping

2011-01-01

Transparent conducting electrodes with the combination of high optical transmission and good electrical conductivity are essential for solar energy harvesting and electric lighting devices. Currently, indium tin oxide (ITO) is used because ITO offers relatively high transparency (>80%) to visible light and low sheet resistance (R s = 10 ohms/square (Ω /2)) for electrical conduction. However, ITO is costly due to limited indium reserves, and it is brittle. These disadvantages have motivated the search for other conducting electrodes with similar or better properties. There has been research on a variety of electrode structures involving carbon nanotube networks, graphene films, nanowiremore » and nanopatterned meshes and grids. Due to their novel characteristics in light manipulation and collection, photonic crystal structures show promise for further improvement. Here, we report on a new architecture consisting of nanoscale high aspect ratio metallic photonic structures as transparent electrodes fabricated via a combination of processes. For (Au) and silver (Ag) structures, the visible light transmission can reach as high as 80%, and the sheet resistance of the structure can be as low as 3.2Ω /2. The optical transparency of the high aspect ratio metal structures at visible wavelength range is comparable to that of ITO glass, while their sheet resistance is more than 3 times lower, which indicates a much higher electrical conductivity of the metal structures. Furthermore, the high aspect ratio metal structures have very high infrared (IR) reflection (90%) for the transverse magnetic (TM) mode, which can lead to the development of fabrication of metallic structures as IR filters for heat control applications. Investigations of interdigitated structures based on the high aspect ratio metal electrodes are ongoing to study the feasibility in smart window applications in light transmission modulation.« less

Rolled-up inductor structure for a radiofrequency integrated circuit (RFIC)

DOEpatents

Li, Xiuling; Huang, Wen; Ferreira, Placid M.; Yu, Xin

2015-12-29

A rolled-up inductor structure for a radiofrequency integrated circuit (RFIC) comprises a multilayer sheet in a rolled configuration comprising multiple turns about a longitudinal axis. The multilayer sheet comprises a conductive pattern layer on a strain-relieved layer, and the conductive pattern layer comprises at least one conductive strip having a length extending in a rolling direction. The at least one conductive strip thereby wraps around the longitudinal axis in the rolled configuration. The conductive pattern layer may also comprise two conductive feed lines connected to the conductive strip for passage of electrical current therethrough. The conductive strip serves as an inductor cell of the rolled-up inductor structure.

Sequentially bridged graphene sheets with high strength, toughness, and electrical conductivity

PubMed Central

Wan, Sijie; Li, Yuchen; Mu, Jiuke; Aliev, Ali E.; Fang, Shaoli; Kotov, Nicholas A.; Jiang, Lei; Cheng, Qunfeng; Baughman, Ray H.

2018-01-01

We here show that infiltrated bridging agents can convert inexpensively fabricated graphene platelet sheets into high-performance materials, thereby avoiding the need for a polymer matrix. Two types of bridging agents were investigated for interconnecting graphene sheets, which attach to sheets by either π–π bonding or covalent bonding. When applied alone, the π–π bonding agent is most effective. However, successive application of the optimized ratio of π–π bonding and covalent bonding agents provides graphene sheets with the highest strength, toughness, fatigue resistance, electrical conductivity, electromagnetic interference shielding efficiency, and resistance to ultrasonic dissolution. Raman spectroscopy measurements of stress transfer to graphene platelets allow us to decipher the mechanisms of property improvement. In addition, the degree of orientation of graphene platelets increases with increasing effectiveness of the bonding agents, and the interlayer spacing increases. Compared with other materials that are strong in all directions within a sheet, the realized tensile strength (945 MPa) of the resin-free graphene platelet sheets was higher than for carbon nanotube or graphene platelet composites, and comparable to that of commercially available carbon fiber composites. The toughness of these composites, containing the combination of π–π bonding and covalent bonding, was much higher than for these other materials having high strengths for all in-plane directions, thereby opening the path to materials design of layered nanocomposites using multiple types of quantitatively engineered chemical bonds between nanoscale building blocks. PMID:29735659

Effect of an MLT dependent electron loss rate on the inner magnetosphere electrodynamics and plasma sheet penetration to the ring current region

NASA Astrophysics Data System (ADS)

Gkioulidou, M.; Wang, C.; Wing, S.; Lyons, L. R.; Wolf, R. A.; Hsu, T.

2012-12-01

Transport of plasma sheet particles into the ring current region is strongly affected by the penetrating convection electric field, which is the result of the large-scale magnetosphere-ionosphere (M-I) electromagnetic coupling. One of the main factors controlling this coupling is the ionospheric conductance. As plasma sheet electrons drift earthward, they get scattered into the loss cone due to wave-particle interactions and precipitate to the ionosphere, producing auroral conductance. Realistic electron loss is thus important for modeling the (M-I) coupling and penetration of plasma sheet into the inner magnetosphere. To evaluate the significance of electron loss rate, we used the Rice Convection Model (RCM) coupled with a force-balanced magnetic field to simulate plasma sheet transport under different electron loss rates and under self-consistent electric and magnetic field. The plasma sheet ion and electron sources for the simulations are based on the Geotail observations. Two major rates are used: different portions of i) strong pitch-angle diffusion everywhere electron loss rate (strong rate) and ii) a more realistic loss rate with its MLT dependence determined by wave activity (MLT rate). We found that the dawn-dusk asymmetry in the precipitating electron energy flux under the MLT rate, with much higher energy flux at dawn than at dusk, agrees better with statistical DMSP observations. Electrons trapped inside L ~ 8 RE can remain there for many hours under the MLT rate, while those under the strong rate get lost within minutes. Compared with the strong rate, the remaining electrons under the MLT rate cause higher conductance at lower latitudes, allowing for less efficient electric field shielding to convection enhancement, thus further earthward penetration of the plasma sheet into the inner magnetosphere. Therefore, our simulation results indicate that the electron loss rate can significantly affect the electrodynamics of the ring current region. Development of a more realistic electron loss rate model for the inner magnetosphere is thus much needed and will become feasible with new observations from the upcoming RBSP mission.

Self-diagnosis of structures strengthened with hybrid carbon-fiber-reinforced polymer sheets

NASA Astrophysics Data System (ADS)

Wu, Z. S.; Yang, C. Q.; Harada, T.; Ye, L. P.

2005-06-01

The correlation of mechanical and electrical properties of concrete beams strengthened with hybrid carbon-fiber-reinforced polymer (HCFRP) sheets is studied in this paper. Two types of concrete beams, with and without reinforcing bars, are strengthened with externally bonded HCFRP sheets, which have a self-structural health monitoring function due to the electrical conduction and piezoresistivity of carbon fibers. Parameters investigated include the volume fractions and types of carbon fibers. According to the investigation, it is found that the hybridization of uniaxial HCFRP sheets with several different types of carbon fibers is a viable method for enhancing the mechanical properties and obtaining a built-in damage detection function for concrete structures. The changes in electrical resistance during low strain ranges before the rupture of carbon fibers are generally smaller than 1%. Nevertheless, after the gradual ruptures of carbon fibers, the electrical resistance increases remarkably with the strain in a step-wise manner. For the specimens without reinforcing bars, the electrical behaviors are not stable, especially during the low strain ranges. However, the electrical behaviors of the specimens with reinforcing bars are relatively stable, and the whole range of self-sensing function of the HCFRP-strengthened RC structures has realized the conceptual design of the HCFRP sensing models and is confirmed by the experimental investigations. The relationships between the strain/load and the change in electrical resistance show the potential self-monitoring capacity of HCFRP reinforcements used for strengthening concrete structures.

The source of the electric field in the nightside magnetosphere

NASA Technical Reports Server (NTRS)

Stern, D. P.

1975-01-01

In the open magnetosphere model magnetic field lines from the polar caps connect to the interplanetary magnetic field and conduct an electric field from interplanetary space to the polar ionosphere. By examining the magnetic flux involved it is concluded that only slightly more than half of the magnetic flux in the polar caps belongs to open field lines and that such field lines enter or leave the magnetosphere through narrow elongated windows stretching the tail. These window regions are identified with the tail's boundary region and shift their position with changes in the interplanetary magnetic field, in particular when a change of interplanetary magnetic sector occurs. The circuit providing electric current in the magnetopause and the plasma sheet is extended across those windows; thus energy is drained from the interplanetary electric field and an electric potential drop is produced across the plasma sheet. The polar cap receives its electric field from interplanetary space on the day side from open magnetic field lines and on the night side from closed field lines leading to the plasma sheet. The theory described provides improved understanding of magnetic flux bookkeeping, of the origin of Birkeland currents, and of the boundary layer of the geomagnetic tail.

Hydroxylated graphene-based flexible carbon film with ultrahigh electrical and thermal conductivity.

PubMed

Ding, Jiheng; Ur Rahman, Obaid; Zhao, Hongran; Peng, Wanjun; Dou, Huimin; Chen, Hao; Yu, Haibin

2017-09-29

Graphene-based films are widely used in the electronics industry. Here, surface hydroxylated graphene sheets (HGS) have been synthesized from natural graphite (NG) by a rapid and efficient molten hydroxide-assisted exfoliation technique. This method enables preparation of aqueous dispersible graphene sheets with a high dispersed concentration (∼10.0 mg ml -1 ) and an extraordinary production yield (∼100%). The HGS dispersion was processed into graphene flexible film (HGCF) through fast filtration, annealing treatment and mechanical compression. The HGS endows graphene flexible film with a high electrical conductivity of 11.5 × 10 4 S m -1 and a superior thermal conductivity of 1842 W m -1 K -1 . Simultaneously, the superflexible HGCF could endure 3000 repeated cycles of bending or folding. As a result, this graphene flexible film is expected to be integrated into electronic packaging and high-power electronics applications.

Solid oxide fuel cell with multi-unit construction and prismatic design

DOEpatents

McPheeters, Charles C.; Dees, Dennis W.; Myles, Kevin M.

1999-01-01

A single cell unit of a solid oxide fuel cell that is individually fabricated and sintered prior to being connected to adjacent cells to form a solid oxide fuel cell. The single cell unit is comprised of a shaped anode sheet positioned between a flat anode sheet and an anode-electrolyte-cathode (A/E/C) sheet, and a shaped cathode sheet positioned between the A/E/C sheet and a cathode-interconnect-anode (C/I/A) sheet. An alternate embodiment comprises a shaped cathode sheet positioned between an A/E/C sheet and a C/I/A sheet. The shaped sheets form channels for conducting reactant gases. Each single cell unit is individually sintered to form a finished sub-assembly. The finished sub-assemblies are connected in electrical series by interposing connective material between the end surfaces of adjacent cells, whereby individual cells may be inspected for defects and interchanged with non-defective single cell units.

Characterization of the mechanical and physical properties of TD-NiCr (Ni-20Cr-2ThO2) alloy sheet

NASA Technical Reports Server (NTRS)

Fritz, L. J.; Koster, W. P.; Taylor, R. E.

1973-01-01

Sheets of TD-NiCr processed using techniques developed to produce uniform material were tested to supply mechanical and physical property data. Two heats each of 0.025 and 0.051 cm thick sheet were tested. Mechanical properties evaluated included tensile, modulus of elasticity, Poisson's Ratio, compression, creep-rupture, creep strength, bearing strength, shear strength, sharp notch and fatigue strength. Test temperatures covered the range from ambient to 1589K. Physical properties were also studied as a function of temperature. The physical properties measured were thermal conductivity, linear thermal expansion, specific heat, total hemispherical emittance, thermal diffusivity, and electrical conductivity.

Evaluating conducting network based transparent electrodes from geometrical considerations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Ankush; Kulkarni, G. U., E-mail: guk@cens.res.in

2016-01-07

Conducting nanowire networks have been developed as viable alternative to existing indium tin oxide based transparent electrode (TE). The nature of electrical conduction and process optimization for electrodes have gained much from the theoretical models based on percolation transport using Monte Carlo approach and applying Kirchhoff's law on individual junctions and loops. While most of the literature work pertaining to theoretical analysis is focussed on networks obtained from conducting rods (mostly considering only junction resistance), hardly any attention has been paid to those made using template based methods, wherein the structure of network is neither similar to network obtained frommore » conducting rods nor similar to well periodic geometry. Here, we have attempted an analytical treatment based on geometrical arguments and applied image analysis on practical networks to gain deeper insight into conducting networked structure particularly in relation to sheet resistance and transmittance. Many literature examples reporting networks with straight or curvilinear wires with distributions in wire width and length have been analysed by treating the networks as two dimensional graphs and evaluating the sheet resistance based on wire density and wire width. The sheet resistance values from our analysis compare well with the experimental values. Our analysis on various examples has revealed that low sheet resistance is achieved with high wire density and compactness with straight rather than curvilinear wires and with narrower wire width distribution. Similarly, higher transmittance for given sheet resistance is possible with narrower wire width but of higher thickness, minimal curvilinearity, and maximum connectivity. For the purpose of evaluating active fraction of the network, the algorithm was made to distinguish and quantify current carrying backbone regions as against regions containing only dangling or isolated wires. The treatment can be helpful in predicting the properties of a network simply from image analysis and will be helpful in improvisation and comparison of various TEs and better understanding of electrical percolation.« less

Evaluating conducting network based transparent electrodes from geometrical considerations

NASA Astrophysics Data System (ADS)

Kumar, Ankush; Kulkarni, G. U.

2016-01-01

Conducting nanowire networks have been developed as viable alternative to existing indium tin oxide based transparent electrode (TE). The nature of electrical conduction and process optimization for electrodes have gained much from the theoretical models based on percolation transport using Monte Carlo approach and applying Kirchhoff's law on individual junctions and loops. While most of the literature work pertaining to theoretical analysis is focussed on networks obtained from conducting rods (mostly considering only junction resistance), hardly any attention has been paid to those made using template based methods, wherein the structure of network is neither similar to network obtained from conducting rods nor similar to well periodic geometry. Here, we have attempted an analytical treatment based on geometrical arguments and applied image analysis on practical networks to gain deeper insight into conducting networked structure particularly in relation to sheet resistance and transmittance. Many literature examples reporting networks with straight or curvilinear wires with distributions in wire width and length have been analysed by treating the networks as two dimensional graphs and evaluating the sheet resistance based on wire density and wire width. The sheet resistance values from our analysis compare well with the experimental values. Our analysis on various examples has revealed that low sheet resistance is achieved with high wire density and compactness with straight rather than curvilinear wires and with narrower wire width distribution. Similarly, higher transmittance for given sheet resistance is possible with narrower wire width but of higher thickness, minimal curvilinearity, and maximum connectivity. For the purpose of evaluating active fraction of the network, the algorithm was made to distinguish and quantify current carrying backbone regions as against regions containing only dangling or isolated wires. The treatment can be helpful in predicting the properties of a network simply from image analysis and will be helpful in improvisation and comparison of various TEs and better understanding of electrical percolation.

The Conductive Silver Nanowires Fabricated by Two-beam Laser Direct Writing on the Flexible Sheet.

PubMed

He, Gui-Cang; Zheng, Mei-Ling; Dong, Xian-Zi; Jin, Feng; Liu, Jie; Duan, Xuan-Ming; Zhao, Zhen-Sheng

2017-02-02

Flexible electrically conductive nanowires are now a key component in the fields of flexible devices. The achievement of metal nanowire with good flexibility, conductivity, compact and smooth morphology is recognized as one critical milestone for the flexible devices. In this study, a two-beam laser direct writing system is designed to fabricate AgNW on PET sheet. The minimum width of the AgNW fabricated by this method is 187 ± 34 nm with the height of 84 ± 4 nm. We have investigated the electrical resistance under different voltages and the applicable voltage per meter range is determined to be less than 7.5 × 10 3  V/m for the fabricated AgNW. The flexibility of the AgNW is very excellent, since the resistance only increases 6.63% even after the stretched bending of 2000 times at such a small bending radius of 1.0 mm. The proposed two-beam laser direct writing is an efficient method to fabricate AgNW on the flexible sheet, which could be applied in flexible micro/nano devices.

Conducting Polymer Coated Graphene Oxide Electrode for Rechargeable Lithium-Sulfur Batteries.

PubMed

Lee, Hee-Yoon; Jung, Yongju; Kim, Seok

2016-03-01

Poly(diallyldimethylammonium chloride) (PDDA)/graphene oxide-sulfur composites were prepared by a chemical oxidation method. For the PDDA-GO composites, conducting polymers (PDDA) were coated on the surface of GO sheets. PDDA-GO composites could be expected to increase electrical conductivity and protect restacking of graphene sheets. And then, sulfur particles were dispersed into the PDDA-GO composites by mixing in the CS2 solvent. It is expected the PDDA-GO/S composites show the limited release of polysulfides due to the fact that it can provide high surface area, because conducting polymer can be used as spacer between graphene sheets. Electrochemical performances of prepared composites were characterized by cyclic voltammetry (CV). The PDDA-GO/S composites showed a high discharge capacity of 1102 mAh g(-1) at the first cycle and a good cycle retention of 60% after 100 cycles.

Fabrication of ATO/Graphene Multi-layered Transparent Conducting Thin Films

NASA Astrophysics Data System (ADS)

Li, Na; Chen, Fei; Shen, Qiang; Wang, Chuanbin; Zhang, Lianmeng

2013-03-01

A novel transparent conducting oxide based on the ATO/graphene multi-layered thin films has been developed to satisfy the application of transparent conductive electrode in solar cells. The ATO thin films are prepared by pulsed laser deposition method with high quality, namely the sheet resistance of 49.5 Ω/sq and average transmittance of 81.9 %. The prepared graphene sheet is well reduced and shows atomically thin, spotty distributed appearance on the top of the ATO thin films. The XRD and optical micrographs are used to confirm the successfully preparation of the ATO/graphene multi-layered thin films. The Hall measurements and UV-Vis spectrophotometer are conducted to evaluate the sheet resistance and optical transmittance of the innovative structure. It is found that graphene can improve the electrical properties of the ATO thin films with little influence on the optical transmittance.

Is hexagonal boron nitride always good as a substrate for carbon nanotube-based devices?

PubMed

Kang, Seoung-Hun; Kim, Gunn; Kwon, Young-Kyun

2015-02-21

Hexagonal boron nitride sheets have been noted especially for their enhanced properties as substrates for sp(2) carbon-based nanodevices. To evaluate whether such enhanced properties would be retained under various realistic conditions, we investigate the structural and electronic properties of semiconducting carbon nanotubes on perfect and defective hexagonal boron nitride sheets under an external electric field as well as with a metal impurity, using density functional theory. We verify that the use of a perfect hexagonal boron nitride sheet as a substrate indeed improves the device performances of carbon nanotubes, compared with the use of conventional substrates such as SiO2. We further show that even the hexagonal boron nitride with some defects can show better performance as a substrate. Our calculations, on the other hand, also suggest that some defective boron nitride layers with a monovacancy and a nickel impurity could bring about poor device behavior since the imperfections impair electrical conductivity due to residual scattering under an applied electric field.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazzarella, Ricardo; Slocum, Alexander H.; Doherty, Tristan

Electrochemical cells and methods of making electrochemical cells are described herein. In some embodiments, an apparatus includes a multi-layer sheet for encasing an electrode material for an electrochemical cell. The multi-layer sheet including an outer layer, an intermediate layer that includes a conductive substrate, and an inner layer disposed on a portion of the conductive substrate. The intermediate layer is disposed between the outer layer and the inner layer. The inner layer defines an opening through which a conductive region of the intermediate layer is exposed such that the electrode material can be electrically connected to the conductive region. Thus,more » the intermediate layer can serve as a current collector for the electrochemical cell.« less

Electrochemical cells and methods of manufacturing the same

DOEpatents

Bazzarella, Ricardo; Slocum, Alexander H; Doherty, Tristan; Cross, III, James C

2015-11-03

Electrochemical cells and methods of making electrochemical cells are described herein. In some embodiments, an apparatus includes a multi-layer sheet for encasing an electrode material for an electrochemical cell. The multi-layer sheet including an outer layer, an intermediate layer that includes a conductive substrate, and an inner layer disposed on a portion of the conductive substrate. The intermediate layer is disposed between the outer layer and the inner layer. The inner layer defines an opening through which a conductive region of the intermediate layer is exposed such that the electrode material can be electrically connected to the conductive region. Thus, the intermediate layer can serve as a current collector for the electrochemical cell.

The impact of finite-area inhomogeneities on resistive and Hall measurement

NASA Astrophysics Data System (ADS)

Koon, Daniel

2013-03-01

I derive an iterative expression for the electric potential in an otherwise homogeneous thin specimen as the result of a finite-area inhomogeneity in either the direct conductance, the Hall conductance, or both. This expression extends to the finite-area regime the calculation of the effect of such inhomogeneities on the measurement error in the sheet resistance and Hall sheet resistance. I then test these results on the exactly-solvable case of a circular inhomogeneity equally distant from the four electrodes of either a square four-point-probe array on an infinitely large conducting specimen or a circular van der Pauw specimen with symmetrically-placed electrodes.

Dimensional Analysis and Electric Potential Due to a Uniformly Charged Sheet

ERIC Educational Resources Information Center

Aghamohammadi, Amir

2011-01-01

Dimensional analysis, superposition principle, and continuity of electric potential are used to study the electric potential of a uniformly charged square sheet on its plane. It is shown that knowing the electric potential on the diagonal and inside the square sheet is equivalent to knowing it everywhere on the plane of the square sheet. The…

Graphene Sheet-Induced Global Maturation of Cardiomyocytes Derived from Human Induced Pluripotent Stem Cells.

PubMed

Wang, Jiaxian; Cui, Chang; Nan, Haiyan; Yu, Yuanfang; Xiao, Yini; Poon, Ellen; Yang, Gang; Wang, Xijie; Wang, Chenchen; Li, Lingsong; Boheler, Kenneth Richard; Ma, Xu; Cheng, Xin; Ni, Zhenhua; Chen, Minglong

2017-08-09

Human induced pluripotent stem cells (hiPSCs) can proliferate infinitely. Their ability to differentiate into cardiomyocytes provides abundant sources for disease modeling, drug screening and regenerative medicine. However, hiPSC-derived cardiomyocytes (hiPSC-CMs) display a low degree of maturation and fetal-like properties. Current in vitro differentiation methods do not mimic the structural, mechanical, or physiological properties of the cardiogenesis niche. Recently, we present an efficient cardiac maturation platform that combines hiPSCs monolayer cardiac differentiation with graphene substrate, which is a biocompatible and superconductive material. The hiPSCs lines were successfully maintained on the graphene sheets and were able to differentiate into functional cardiomyocytes. This strategy markedly increased the myofibril ultrastructural organization, elevated the conduction velocity, and enhanced both the Ca 2+ handling and electrophysiological properties in the absence of electrical stimulation. On the graphene substrate, the expression of connexin 43 increased along with the conduction velocity. Interestingly, the bone morphogenetic proteins signaling was also significantly activated during early cardiogenesis, confirmed by RNA sequencing analysis. Here, we reasoned that graphene substrate as a conductive biomimetic surface could facilitate the intrinsic electrical propagation, mimicking the microenvironment of the native heart, to further promote the global maturation of hiPSC-CMs. Our findings highlight the capability of electrically active substrates to influence cardiomyocyte development. We believe that application of graphene sheets will be useful for simple, fast, and scalable maturation of regenerated cardiomyocytes.

Beyond the Point Charge: Equipotential Surfaces and Electric Fields of Various Charge Configurations

ERIC Educational Resources Information Center

Phillips, Jeffrey A.; Sanny, Jeff; Berube, David; Hoemke, Anatol

2017-01-01

A laboratory experiment often performed in an introductory electricity and magnetism course involves the mapping of equipotential lines on a conductive sheet between two objects at different potentials. In this article, we describe how we have expanded this experiment so that it can be used to illustrate the electrostatic properties of conductors.…

FDTD modeling of thin impedance sheets

NASA Technical Reports Server (NTRS)

Luebbers, Raymond; Kunz, Karl

1991-01-01

Thin sheets of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such sheets is simplified by using sheet impedances. It is shown that sheet impedances can be modeled easily and accurately using Finite Difference Time Domain (FDTD) methods. These sheets are characterized by a discontinuity in the tangential magnetic field on either side of the sheet but no discontinuity in tangential electric field. This continuity, or single valued behavior of the electric field, allows the sheet current to be expressed in terms of an impedance multiplying this electric field.

High-fidelity Characterization on Anisotropic Thermal Conductivity of Carbon Nanotube Sheets and on their effects of Thermal Enhancement of Nanocomposites.

PubMed

Zhang, Xiao; Tan, Wei; Smail, Fiona; De Volder, Michael; Fleck, Norman; Boies, Adam

2018-06-19

Some assemblies of nanomaterials, like carbon nanotube (CNT) sheet or film, always show outstanding and anisotropic thermal properties. However, there is still a lack of comprehensive thermal conductivity (κ) characterizations on CNT sheets, as well as lack of estimations of their true contributions on thermal enhancement of polymer composites when used as additives. Always, these characterizations were hindered by the low heat capacity, anisotropic thermal properties or low electrical conductivity of assemblies and their nanocomposites. And the transient κ measurement and calculations were also hampered by accurate determination of parameters, like specific heat capacity, density and cross-section, which could be difficult and controversial for nanomaterials, like CNT sheets. Here, to measure anisotropic κ of CNT sheets directly with high fidelity, we modified the conventional steady-state method by measuring under vacuum and by infrared camera, and then comparing temperature profiles on both reference standard material and a CNT sheet sample. The highly anisotropic thermal conductivities of CNT sheets were characterized comprehensively, with κ/ρ in alignment direction as ~95 mW·m^2/(K·kg). Furthermore, by comparing the measured thermal properties of different CNT-epoxy resin composites, the heat conduction pathway created by the CNT hierarchical network was demonstrated to remain intact after the in-situ polymerization and curing process. The reliable and direct κ measurement rituals used here, dedicated to nanomaterials, will be also essential to assist in assemblies' application to heat dissipation and composite thermal enhancement. © 2018 IOP Publishing Ltd.

Self-healable electrically conducting wires for wearable microelectronics.

PubMed

Sun, Hao; You, Xiao; Jiang, Yishu; Guan, Guozhen; Fang, Xin; Deng, Jue; Chen, Peining; Luo, Yongfeng; Peng, Huisheng

2014-09-01

Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next-generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high-performance conducting wires that can self-heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self-healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self-healable wire-shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self-healing. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng

An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the firstmore » exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.« less

Solid oxide fuel cell with multi-unit construction and prismatic design

DOEpatents

McPheeters, C.C.; Dees, D.W.; Myles, K.M.

1999-03-16

A single cell unit of a solid oxide fuel cell is described that is individually fabricated and sintered prior to being connected to adjacent cells to form a solid oxide fuel cell. The single cell unit is comprised of a shaped anode sheet positioned between a flat anode sheet and an anode-electrolyte-cathode (A/E/C) sheet, and a shaped cathode sheet positioned between the A/E/C sheet and a cathode-interconnect-anode (C/I/A) sheet. An alternate embodiment comprises a shaped cathode sheet positioned between an A/E/C sheet and a C/I/A sheet. The shaped sheets form channels for conducting reactant gases. Each single cell unit is individually sintered to form a finished sub-assembly. The finished sub-assemblies are connected in electrical series by interposing connective material between the end surfaces of adjacent cells, whereby individual cells may be inspected for defects and interchanged with non-defective single cell units. 7 figs.

Controllable in situ synthesis of epsilon manganese dioxide hollow structure/RGO nanocomposites for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Lin, Mei; Chen, Bolei; Wu, Xiao; Qian, Jiasheng; Fei, Linfeng; Lu, Wei; Chan, Lai Wa Helen; Yuan, Jikang

2016-01-01

Well-organized epsilon-MnO2 hollow spheres/reduced graphene oxide (MnO2HS/RGO) composites have been successfully constructed via a facile and one-pot synthetic route. The ε-MnO2 hollow spheres with the diameter of ~500 nm were grown in situ with homogeneous distribution on both sides of graphene oxide (GO) sheets in aqueous suspensions. The formation mechanism of the MnO2HS/RGO composites has been systematically investigated, and a high specific capacitance and good cycling capability were achieved on using the composites as supercapacitors. The galvanostatic charge/discharge curves show a specific capacitance of 471.5 F g-1 at 0.8 A g-1. The hollow structures of ε-MnO2 and the crumpled RGO sheets can enhance the electroactive surface area and improve the electrical conductivity, thus further facilitating the charge transport. The MnO2HS/RGO composite exhibits a high capacitance of 272 F g-1 at 3 A g-1 (92% retention) even after 1000 cycles. The prominent electrochemical performance might be attributed to the combination of the pseudo-capacitance of the MnO2 nanospheres with a hollow structure and to the good electrical conductivity of the RGO sheets. This work explores a new concept in designing metal oxides/RGO composites as electrode materials.Well-organized epsilon-MnO2 hollow spheres/reduced graphene oxide (MnO2HS/RGO) composites have been successfully constructed via a facile and one-pot synthetic route. The ε-MnO2 hollow spheres with the diameter of ~500 nm were grown in situ with homogeneous distribution on both sides of graphene oxide (GO) sheets in aqueous suspensions. The formation mechanism of the MnO2HS/RGO composites has been systematically investigated, and a high specific capacitance and good cycling capability were achieved on using the composites as supercapacitors. The galvanostatic charge/discharge curves show a specific capacitance of 471.5 F g-1 at 0.8 A g-1. The hollow structures of ε-MnO2 and the crumpled RGO sheets can enhance the electroactive surface area and improve the electrical conductivity, thus further facilitating the charge transport. The MnO2HS/RGO composite exhibits a high capacitance of 272 F g-1 at 3 A g-1 (92% retention) even after 1000 cycles. The prominent electrochemical performance might be attributed to the combination of the pseudo-capacitance of the MnO2 nanospheres with a hollow structure and to the good electrical conductivity of the RGO sheets. This work explores a new concept in designing metal oxides/RGO composites as electrode materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07900d

Field-aligned current sources in the high-latitude ionosphere

NASA Technical Reports Server (NTRS)

Barbosa, D. D.

1979-01-01

The paper determines the electric potential in a plane which is fed current from a pair of field-aligned current sheets. The ionospheric conductivity is modelled as a constant with an enhanced conductivity annular ring. It is shown that field-aligned current distributions are arbitrary functions of azimuth angle (MLT) and thus allow for asymmetric potential configurations over the pole cap. In addition, ionospheric surface currents are computed by means of stream functions. Finally, the discussion relates these methods to the electrical characteristics of the magnetosphere.

Mechanical behavior enhancement of defective graphene sheet employing boron nitride coating via atomistic study

NASA Astrophysics Data System (ADS)

Setoodeh, A. R.; Badjian, H.

2017-12-01

The most stable form of boron nitride polymorph naming hexagonal boron nitride sheet has recently been widely concerned like graphite due to its interesting features such as electrical insulation and high thermal conductivity. In this study, the molecular dynamic simulations are implemented to investigate the mechanical properties of single-layer graphene sheets under tensile and compressive loadings in the absence and presence of boron-nitride coating layers. In this introduced hybrid nanostructure, the benefit of combining both individual interesting features of graphene and boron-nitride sheets such as exceptional mechanical and electrical properties can be simultaneously achieved for future potential application in nano devices. The influences of chiral indices, boundary conditions and presence of mono-atomic vacancy defects as well as coating dimension on the mechanical behavior of the resulted hybrid structure are reported. The interatomic forces between the atoms are modeled by employing the AIREBO and Tersoff-Brenner potentials for carbon-carbon and boron-nitrogen atoms in each layer, respectively. Furthermore, the van der Waal interlayer forces of carbon-boron and carbon-nitrogen are estimated by the Lennard-Jones potential field. Besides the potential improvement in electrical and physical properties of the nanostructure, it is demonstrated that the buckling load capacity of the fully coated graphene sheet with 3% concentration of mono-atomic vacancy defects noticeably enhances by amounts of 24.1%.

Properties of Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Kang, Jin Ho; Grimsley, Brian W.; Ratcliffe, James G.; Siochi, Emilie J.

2016-01-01

For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strength- and stiffness-to-weight ratios, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Carbon nanotubes (CNT) offer the potential to enhance the multi-functionality of composites with improved thermal and electrical conductivity. In this study, hybrid CNT/carbon fiber (CF) polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing. Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated.

A new composite consisting of electrosynthesized conducting polymers, graphene sheets and biosynthesized gold nanoparticles for biosensing acute lymphoblastic leukemia.

PubMed

Mazloum-Ardakani, Mohammad; Barazesh, Behnaz; Khoshroo, Alireza; Moshtaghiun, Mohammad; Sheikhha, Mohammad Hasan

2018-06-01

In this work we report the synthesis of a stable composite with excellent electrical properties, on the surface of a biosensor. Conductive polymers offer both high electrical conductivity and mechanical strength. Many reports have focused on synthesizing conductive polymers with the aid of high-cost enzymes. In the current work we introduce a novel electrochemical, one-step, facile and cost effective procedure for synthesizing poly (catechol), without using expensive enzymes. The poly (catechol) conductivity was enhanced by modification with graphene sheets and biosynthesized gold nanoparticles. Four different robust methods, DPV, EIS, CV and chronoamperometry, were used to monitor the biosensor modifications. The peak currents of the catechol (an electroactive probe) were linearly related to the logarithm of the concentrations of target DNA in the range 100.0 μM to 10.0 pM, with a detection limit of 1.0 pM for the DNA strand. The current work investigates a new, stable composite consisting of conductive polymers and nanoparticles, which was applied to the detection of acute lymphoblastic leukemia. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrochemical cells and methods of manufacturing the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazzarella, Ricardo; Slocum, Alexander H.; Doherty, Tristan

2016-07-26

Electrochemical cells and methods of making electrochemical cells are described herein. In some embodiments, an apparatus includes a multi-layer sheet for encasing an electrode material for an electrochemical cell. The multi-layer sheet including an outer layer, an intermediate layer that includes a conductive substrate, and an inner layer disposed on a portion of the conductive substrate. The intermediate layer is disposed between the outer layer and the inner layer. The inner layer defines an opening through which a conductive region of the intermediate layer is exposed such that the electrode material can be electrically connected to the conductive region. Thus,more » the intermediate layer can serve as a current collector for the electrochemical cell.« less

Laser processing for strengthening of the self-restoring metal-elastomer interface on a silicone sheet

NASA Astrophysics Data System (ADS)

Yasuda, Kiyokazu

2012-08-01

A self-restoring microsystem is a unique concept which realizes the sensing functionality and robust interface which mechanically and electrically connects a deformable object such as a human body with printed electronic devices. For this purpose, the formation of conductive wiring on an elastomer substrate was attempted using the nickel ink printing process. Before the wiring process, surface patterning of a silicone sheet by a galvano-scanned infrared laser was conducted for the enhancement of interface adhesion of the metal deposit and polymer. Characterization of the fabricated pattern was conducted by optical microscopy. The novel method was successfully demonstrated as a fabrication of selective patterns of metal particles on self-restoring MEMS.

Development of potassium ion conducting hollow glass fibers. [potassium sulfur battery

NASA Technical Reports Server (NTRS)

Tsang, F. Y.

1974-01-01

Potassium ion conducting glasses, chemically resistant to potassium, potassium sulfide and sulfur, were made and their possible utility as the membrane material for a potassium/sulfur battery was evaluated. At least one satisfactory candidate was found. It possesses an electrical resistance which makes it usable as a membrane in the form of a fine hollow fiber. It's chemical and electrochemical resistances are excellent. The other aspects of the possible potassium sulfur battery utilizing such fine hollow fibers, including the header (or tube sheet) and a cathode current collector were studied. Several cathode materials were found to be satisfactory. None of the tube sheet materials studied possessed all the desired properties. Multi-fiber cells had very limited life-time due to physical failure of fibers at the fiber/tube sheet junctions.

Printed Electronics

NASA Technical Reports Server (NTRS)

Lettow, John S. (Inventor); Crain, John M. (Inventor); Aksay, Ilhan A. (Inventor); Korkut, Sibel (Inventor); Chiang, Katherine S. (Inventor); Chen, Chuan-Hua (Inventor); Prud'Homme, Robert K. (Inventor)

2016-01-01

Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

Printed Electronics

NASA Technical Reports Server (NTRS)

Korkut, Sibel (Inventor); Chiang, Katherine S. (Inventor); Crain, John M. (Inventor); Aksay, Ilhan A. (Inventor); Lettow, John S. (Inventor); Chen, Chuan-Hua (Inventor); Prud'Homme, Robert K. (Inventor)

2018-01-01

Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

Printed Electronics

NASA Technical Reports Server (NTRS)

Aksay, Ilhan A. (Inventor); Chen, Chuan-Hua (Inventor); Lettow, John S. (Inventor); Chiang, Katherine S. (Inventor); Prud'Homme, Robert K. (Inventor); Crain, John M. (Inventor); Korkut, Sibel (Inventor)

2015-01-01

Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

Printed Electronics

NASA Technical Reports Server (NTRS)

Aksay, Ilhan A. (Inventor); Crain, John M. (Inventor); Chiang, Katherine S. (Inventor); Prud'Homme, Robert K. (Inventor); Lettow, John S. (Inventor); Korkut, Sibel A. (Inventor); Chen, Chuan-Hua (Inventor)

2014-01-01

Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

Printed electronics

NASA Technical Reports Server (NTRS)

Lettow, John S. (Inventor); Prud'Homme, Robert K. (Inventor); Crain, John M. (Inventor); Aksay, Ilhan A. (Inventor); Korkut, Sibel A. (Inventor); Chiang, Katherine S. (Inventor); Chen, Chuan-hua (Inventor)

2012-01-01

Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

Electrostatically clean solar array

NASA Technical Reports Server (NTRS)

Stern, Theodore Garry (Inventor); Krumweide, Duane Eric (Inventor)

2004-01-01

Provided are methods of manufacturing an electrostatically clean solar array panel and the products resulting from the practice of these methods. The preferred method uses an array of solar cells, each with a coverglass where the method includes machining apertures into a flat, electrically conductive sheet so that each aperture is aligned with and undersized with respect to its matched coverglass sheet and thereby fashion a front side shield with apertures (FSA). The undersized portion about each aperture of the bottom side of the FSA shield is bonded to the topside portions nearest the edges of each aperture's matched coverglass. Edge clips are attached to the front side aperture shield edges with the edge clips electrically and mechanically connecting the tops of the coverglasses to the solar panel substrate. The FSA shield, edge clips and substrate edges are bonded so as to produce a conductively grounded electrostatically clean solar array panel.

Environmental Synthesis of Few Layers Graphene Sheets Using Ultrasonic Exfoliation with Enhanced Electrical and Thermal Properties.

PubMed

Noroozi, Monir; Zakaria, Azmi; Radiman, Shahidan; Abdul Wahab, Zaidan

2016-01-01

In this paper, we report how few layers graphene that can be produced in large quantity with low defect ratio from exfoliation of graphite by using a high intensity probe sonication in water containing liquid hand soap and PVP. It was founded that the graphene powder obtained by this simple exfoliation method after the heat treatment had an excellent exfoliation into a single or layered graphene sheets. The UV-visible spectroscopy, FESEM, TEM, X-ray powder diffraction and Raman spectroscopy was used to analyse the graphene product. The thermal diffusivity of the samples was analysed using a highly accurate thermal-wave cavity photothermal technique. The data obtained showed excellent enhancement in the thermal diffusivity of the graphene dispersion. This well-dispersed graphene was then used to fabricate an electrically conductive polymer-graphene film composite. The results demonstrated that this low cost and environmental friendly technique allowed to the production of high quality layered graphene sheets, improved the thermal and electrical properties. This may find use in the wide range of applications based on graphene.

Environmental Synthesis of Few Layers Graphene Sheets Using Ultrasonic Exfoliation with Enhanced Electrical and Thermal Properties

PubMed Central

Noroozi, Monir; Zakaria, Azmi; Radiman, Shahidan; Abdul Wahab, Zaidan

2016-01-01

In this paper, we report how few layers graphene that can be produced in large quantity with low defect ratio from exfoliation of graphite by using a high intensity probe sonication in water containing liquid hand soap and PVP. It was founded that the graphene powder obtained by this simple exfoliation method after the heat treatment had an excellent exfoliation into a single or layered graphene sheets. The UV-visible spectroscopy, FESEM, TEM, X-ray powder diffraction and Raman spectroscopy was used to analyse the graphene product. The thermal diffusivity of the samples was analysed using a highly accurate thermal-wave cavity photothermal technique. The data obtained showed excellent enhancement in the thermal diffusivity of the graphene dispersion. This well-dispersed graphene was then used to fabricate an electrically conductive polymer-graphene film composite. The results demonstrated that this low cost and environmental friendly technique allowed to the production of high quality layered graphene sheets, improved the thermal and electrical properties. This may find use in the wide range of applications based on graphene. PMID:27064575

Mitsubishi iMiEV: An Electric Mini-Car in NREL's Advanced Technology Vehicle Fleet (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This fact sheet highlights the Mitsubishi iMiEV, an electric mini-car in the advanced technology vehicle fleet at the National Renewable Energy Laboratory (NREL). In support of the U.S. Department of Energy's fast-charging research efforts, NREL engineers are conducting charge and discharge performance testing on the vehicle. NREL's advanced technology vehicle fleet features promising technologies to increase efficiency and reduce emissions without sacrificing safety or comfort. The fleet serves as a technology showcase, helping visitors learn about innovative vehicles that are available today or are in development. Vehicles in the fleet are representative of current, advanced, prototype, and emerging technologies.

Energy storage and dissipation in the magnetotail during substorms. I - Particle simulations. II - MHD simulations

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Steinolfson, R. S.

1993-01-01

2D electromagnetic particle simulations are used to investigate the dynamics of the tail during development of substorms under the influence of the pressure in the magnetospheric boundary layer and the dawn-to-dusk electric field. It is shown that pressure pulses result in thinning of the tail current sheet as the magnetic field becomes pinched near the region where the pressure pulse is applied. The pinching leads to the tailward flow of the current sheet plasma and the eventual formation and injection of a plasmoid. Surges in the dawn-to-dusk electric field cause plasma on the flanks to convect into the center of the current sheet, thereby thinning the current sheet. The pressure in the magnetospheric boundary laser is coupled to the dawn-to-dusk electric field through the conductivity of the tail. Changes in the predicted evolution of the magnetosphere during substorms due to changes in the resistivity are investigated under the assumption that MHD theory provides a suitable representation of the global or large-scale evolution of the magnetotail to changes in the solar wind and to reconnection at the dayside magnetopause. It is shown that the overall evolution of the magnetosphere is about the same for three different resistivity distributions with plasmoid formation and ejection in each case.

Swarm observation of field-aligned current and electric field in multiple arc systems

NASA Astrophysics Data System (ADS)

Wu, J.; Knudsen, D. J.; Gillies, M.; Donovan, E.; Burchill, J. K.

2017-12-01

It is often thought that auroral arcs are a direct consequence of upward field-aligned currents. In fact, the relation between currents and brightness is more complicated. Multiple auroral arc systems provide and opportunity to study this relation in detail. In this study, we have identified two types of FAC configurations in multiple parallel arc systems using ground-based optical data from the THEMIS all-sky imagers (ASIs), magnetometers and electric field instruments onboard the Swarm satellites during the period from December 2013 to March 2015. In type 1 events, each arc is an intensification within a broad, unipolar current sheet and downward currents only exist outside the upward current sheet. These types of events are termed "unipolar FAC" events. In type 2 events, multiple arc systems represent a collection of multiple up/down current pairs, which are termed as "multipolar FAC" events. Comparisons of these two types of FAC events are presented with 17 "unipolar FAC" events and 12 "multipolar FAC" events. The results show that "unipolar FAC" and "multipolar FAC" events have systematic differences in terms of MLT, arc width and separation, and dependence on substorm onset time. For "unipolar FAC" events, significant electric field enhancements are shown on the edges of the broad upward current sheet. Electric field fluctuations inside the multiple arc system can be large or small. For "multipolar FAC" events, a strong correlation between magnetic and electric field indicate uniform conductance within each upward current sheet. The electrodynamical structures of multiple arc systems presented in this paper represents a step toward understanding arc generation.

Method and system for sensing and identifying foreign particles in a gaseous environment

NASA Technical Reports Server (NTRS)

Choi, Sang H. (Inventor); Park, Yeonjoon (Inventor)

2008-01-01

An optical method and system sense and identify a foreign particle in a gaseous environment. A light source generates light. An electrically-conductive sheet has an array of holes formed through the sheet. Each hole has a diameter that is less than one quarter of the light's wavelength. The sheet is positioned relative to the light source such that the light is incident on one face of the sheet. An optical detector is positioned adjacent the sheet's opposing face and is spaced apart therefrom such that a gaseous environment is adapted to be disposed there between. Alterations in the light pattern detected by the optical detector indicate the presence of a foreign particle in the holes or on the sheet, while a laser induced fluorescence (LIF) signature associated with the foreign particle indicates the identity of the foreign particle.

Capacitor discharge process for welding braided cable

DOEpatents

Wilson, Rick D.

1995-01-01

A capacitor discharge process for welding a braided cable formed from a plurality of individual cable strands to a solid metallic electrically conductive member comprises the steps of: (a) preparing the electrically conductive member for welding by bevelling one of its end portions while leaving an ignition projection extending outwardly from the apex of the bevel; (b) clamping the electrically conductive member in a cathode fixture; (c) connecting the electrically conductive member clamped in the cathode fixture to a capacitor bank capable of being charged to a preselected voltage value; (d) preparing the braided cable for welding by wrapping one of its end portions with a metallic sheet to form a retaining ring operable to maintain the individual strands of the braided cable in fixed position within the retaining ring; (e) clamping the braided cable and the retaining ring as a unit in an anode fixture so that the wrapped end portion of the braided cable faces the ignition projection of the electrically conductive member; and (f) moving the cathode fixture towards the anode fixture until the ignition projection of the electrically conductive member contacts the end portion of the braided cable thereby allowing the capacitor bank to discharge through the electrically conductive member and through the braided cable and causing the electrically conductive member to be welded to the braided cable via capacitor discharge action.

Structural and Electrical Characteristics of Carbon Nanowalls Synthesized on the Polyimide Film.

PubMed

Kwon, Seok Hun; Kim, Hyung Jin; Choi, Won Seok; Kang, Hyunil

2018-09-01

In this study, the structural and electrical characteristics of carbon nanowalls (CNWs) synthesized on polyimide films were investigated. CNWs were synthesized on polyimide films as various growth times. The cross-section and surface of the CNWs synthesized were examined using FE-SEM. The growth and defects of CNWs were observed by raman spectrum. The hall measurement system was used to analyzed sheet resistance, resistivity and conductivity. The CNWs synthesized at 40 minutes showed outstanding structural and electrical characterizations than another growth times.

Spin- and valley-dependent electrical conductivity of ferromagnetic group-IV 2D sheets in the topological insulator phase

NASA Astrophysics Data System (ADS)

Hoi, Bui Dinh; Yarmohammadi, Mohsen; Mirabbaszadeh, Kavoos; Habibiyan, Hamidreza

2018-03-01

In this work, based on the Kubo-Greenwood formalism and the k . p Hamiltonian model, the impact of Rashba spin-orbit coupling on electronic band structure and electrical conductivity of spin-up and spin-down subbands in counterparts of graphene, including silicene, stanene, and germanene nanosheets has been studied. When Rashba coupling is considered, the effective mass of Dirac fermions decreases significantly and no significant change is caused by this coupling for the subband gaps. All these nanosheets are found to be in topological insulator quantum phase at low staggered on-site potentials due to the applied perpendicular external electric field. We point out that the electrical conductivity of germanene increases gradually with Rashab coupling, while silicene and stanene have some fluctuations due to their smaller Fermi velocity. Furthermore, some critical temperatures with the same electrical conductivity values for jumping to the higher energy levels are observed at various Rashba coupling strengths. For all structures, a broad peak appears at low temperatures in electrical conductivity curves corresponding to the large entropy of systems when the thermal energy reaches to the difference between the energy states. Finally, we have reported that silicene has the larger has the larger electrical conductivity than two others.

High Thermal Conductive BBL/Graphene Nanocomposite System

DTIC Science & Technology

2011-09-02

properties. Composite materials employing carbon -based materials such as carbon - nanotube (CNT), graphene, and fullerene have been explored. However, at...fraction as low as 0.1 vol %, comparable to those observed in carbon nanotube -based composites1c and a conductivity of 0.1 Sm-1, sufficient for many...in both poly(benzimidazobenzophenanthroline) (BBL) and the carbon sheets of the graphene so that the electrical-conductivity levels of the composites

Recent Development of Nanomaterial-Doped Conductive Polymers

NASA Astrophysics Data System (ADS)

Asyraf, Mohammad; Anwar, Mahmood; Sheng, Law Ming; Danquah, Michael K.

2017-12-01

Conductive polymers (CPs) have received significant research attention in material engineering for applications in microelectronics, micro-scale sensors, electromagnetic shielding, and micro actuators. Numerous research efforts have been focused on enhancing the conductivity of CPs by doping. Various conductive materials, such as metal nanoparticles and carbon-based nanoparticles, and structures, such as silver nanoparticles and graphene nanosheets, have been converted into polypyrrole and polypyrrole compounds as the precursors to developing hybrids, conjugates, or crystal nodes within the matrix to enhance the various structural properties, particularly the electrical conductivity. This article reviews nanomaterial doping of conductive polymers alongside technological advancements in the development and application of nanomaterial-doped polymeric systems. Emphasis is given to conductive nanomaterials such as nano-silver particles and carbon-based nanoparticles, graphene nano-sheets, fullerene, and carbon nanotubes (CNT) as dopants for polypyrrole-based CPs. The nature of induced electrical properties including electromagnetic absorption, electrical capacitance, and conductivities of polypyrrole systems is also discussed. The prospects and challenges associated with the development and application of CPs are also presented.

Transparent conducting thin films for spacecraft applications

NASA Technical Reports Server (NTRS)

Perez-Davis, Marla E.; Malave-Sanabria, Tania; Hambourger, Paul; Rutledge, Sharon K.; Roig, David; Degroh, Kim K.; Hung, Ching-Cheh

1994-01-01

Transparent conductive thin films are required for a variety of optoelectronic applications: automotive and aircraft windows, and solar cells for space applications. Transparent conductive coatings of indium-tin-oxide (ITO)-magnesium fluoride (MgF2) and aluminum doped zinc oxide (AZO) at several dopant levels are investigated for electrical resistivity (sheet resistance), carrier concentration, optical properties, and atomic oxygen durability. The sheet resistance values of ITO-MgF2 range from 10(exp 2) to 10(exp 11) ohms/square, with transmittance of 75 to 86 percent. The AZO films sheet resistances range from 10(exp 7) to 10(exp 11) ohms/square with transmittances from 84 to 91 percent. It was found that in general, with respect to the optical properties, the zinc oxide (ZnO), AZO, and the high MgF2 content ITO-MgF2 samples, were all durable to atomic oxygen plasma, while the low MgF2 content of ITO-MgF2 samples were not durable to atomic oxygen plasma exposure.

Transparent conducting thin films for spacecraft applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perez-Davis, M.E.; Malave-Sanabria, T.; Hambourger, P.

1994-01-01

Transparent conductive thin films are required for a variety of optoelectronic applications: automotive and aircraft windows, and solar cells for space applications. Transparent conductive coatings of indium-tin-oxide (ITO)-magnesium fluoride (MgF2) and aluminum doped zinc oxide (AZO) at several dopant levels are investigated for electrical resistivity (sheet resistance), carrier concentration, optical properties, and atomic oxygen durability. The sheet resistance values of ITO-MgF2 range from 10[sup 2] to 10[sup 11] ohms/square, with transmittance of 75 to 86 percent. The AZO films sheet resistances range from 10[sup 7] to 10[sup 11] ohms/square with transmittances from 84 to 91 percent. It was found thatmore » in general, with respect to the optical properties, the zinc oxide (ZnO), AZO, and the high MgF2 content ITO-MgF2 samples, were all durable to atomic oxygen plasma, while the low MgF2 content of ITO-MgF2 samples were not durable to atomic oxygen plasma exposure.« less

Chemical Detection using Electrically Open Circuits having no Electrical Connections

NASA Technical Reports Server (NTRS)

Woodward, Stanley E.; Olgesby, Donald M.; Taylor, Bryant D.; Shams, Qamar A.

2008-01-01

This paper presents investigations to date on chemical detection using a recently developed method for designing, powering and interrogating sensors as electrically open circuits having no electrical connections. In lieu of having each sensor from a closed circuit with multiple electrically connected components, an electrically conductive geometric pattern that is powered using oscillating magnetic fields and capable of storing an electric field and a magnetic field without the need of a closed circuit or electrical connections is used. When electrically active, the patterns respond with their own magnetic field whose frequency, amplitude and bandwidth can be correlated with the magnitude of the physical quantities being measured. Preliminary experimental results of using two different detection approaches will be presented. In one method, a thin film of a reactant is deposited on the surface of the open-circuit sensor. Exposure to a specific targeted reactant shifts the resonant frequency of the sensor. In the second method, a coating of conductive material is placed on a thin non-conductive plastic sheet that is placed over the surface of the sensor. There is no physical contact between the sensor and the electrically conductive material. When the conductive material is exposed to a targeted reactant, a chemical reaction occurs that renders the material non-conductive. The change in the material s electrical resistance within the magnetic field of the sensor alters the sensor s response bandwidth and amplitude, allowing detection of the reaction without having the reactants in physical contact with the sensor.

An overview of a highly versatile forward and stable inverse algorithm for airborne, ground-based and borehole electromagnetic and electric data

NASA Astrophysics Data System (ADS)

Auken, Esben; Christiansen, Anders Vest; Kirkegaard, Casper; Fiandaca, Gianluca; Schamper, Cyril; Behroozmand, Ahmad Ali; Binley, Andrew; Nielsen, Emil; Effersø, Flemming; Christensen, Niels Bøie; Sørensen, Kurt; Foged, Nikolaj; Vignoli, Giulio

2015-07-01

We present an overview of a mature, robust and general algorithm providing a single framework for the inversion of most electromagnetic and electrical data types and instrument geometries. The implementation mainly uses a 1D earth formulation for electromagnetics and magnetic resonance sounding (MRS) responses, while the geoelectric responses are both 1D and 2D and the sheet's response models a 3D conductive sheet in a conductive host with an overburden of varying thickness and resistivity. In all cases, the focus is placed on delivering full system forward modelling across all supported types of data. Our implementation is modular, meaning that the bulk of the algorithm is independent of data type, making it easy to add support for new types. Having implemented forward response routines and file I/O for a given data type provides access to a robust and general inversion engine. This engine includes support for mixed data types, arbitrary model parameter constraints, integration of prior information and calculation of both model parameter sensitivity analysis and depth of investigation. We present a review of our implementation and methodology and show four different examples illustrating the versatility of the algorithm. The first example is a laterally constrained joint inversion (LCI) of surface time domain induced polarisation (TDIP) data and borehole TDIP data. The second example shows a spatially constrained inversion (SCI) of airborne transient electromagnetic (AEM) data. The third example is an inversion and sensitivity analysis of MRS data, where the electrical structure is constrained with AEM data. The fourth example is an inversion of AEM data, where the model is described by a 3D sheet in a layered conductive host.

Structural evaluation of reduced graphene oxide in graphene oxide during ion irradiation: X-ray absorption spectroscopy and in-situ sheet resistance studies

NASA Astrophysics Data System (ADS)

Saravanan, K.; Jayalakshmi, G.; Suresh, K.; Sundaravel, B.; Panigrahi, B. K.; Phase, D. M.

2018-03-01

We report the structural evolution of reduced graphene oxide (rGO) in graphene oxide (GO) flakes during 1 MeV Si+ ion irradiation. In-situ electrical resistivity measurements facilitate monitoring the sheet resistance with the increase in the fluence. The electrical sheet resistance of the GO flake shows the exponential decay behaviour with the increasing ion fluence. Raman spectra of the GO flake reveal the increase in the ID/IG ratio, indicating restoration of the sp2 network upon irradiation. The C/O ratio estimated from resonant Rutherford backscattering spectrometry analysis directly evidenced the reduction of oxygen moieties upon irradiation. C K-edge X-ray absorption near edge structure spectra reveal the restoration of C=C sp2-hybridized carbon atoms and the removal of oxygen-containing functional groups in the GO flake. STM data reveal the higher conductance in the rGO regime in comparison with the regime, where the oxygen functional groups are present. The experimental investigation demonstrates that the ion irradiation can be employed for efficient reduction of GO with tunable electrical and structural properties.

Mechanical property enhancement of high conductive reduced graphene oxide fiber by a small loading of polydopamine

NASA Astrophysics Data System (ADS)

Zeng, Jie; Liu, Yuhang; Han, Di; Yu, Bowen; Deng, Sha; Chen, Feng; Fu, Qiang

2018-04-01

Improving the interaction of individual reduced graphene oxide sheet is an effective way to enhance the mechanical property of reduced graphene oxide fiber. In this study, to enhance the interaction forces of graphene sheets, large-sized graphene oxide sheets were used to assemble graphene fiber, and dopamine was mixed with the graphene oxide spinning drop. During the wet-spinning procedure, polydopamine was formed by polymerizing. It is found that such obtained composite fiber shows enhanced tensile strength (increased from 314 MPa to 527 MPa) and increased toughness (increased from 3.5 MJ m‑3 to 12.9 MJ m‑3) compared with pure reduced graphene oxide fiber. Fourier-transform infrared spectra, Raman spectra and x-ray photoelectron spectroscopy were performed to characterize the interaction between reduced graphene oxide sheets and polydopamine, and a possible enhancement mechanism of C-N bonds formation was proposed. It is suggested that this newly formed C‑N bonds can not only enhance the tensile strength, but also increase the elongation simultaneously. Additionally, the graphene fiber remains great electrical conductivity (33 100 s m‑1) since the conductive network can be maintained.

Overview of Boiler House and Sheet Metal and Electrical Shops ...

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

Overview of Boiler House and Sheet Metal and Electrical Shops Building (center - with single large chimney), note the monitor on the original section of the Boiler House Building, view facing north - Kahului Cannery, Plant No. 28, Boiler House, Sheet Metal and Electrical Shops, 120 Kane Street, Kahului, Maui County, HI

Effect of self-consistent magnetic field on plasma sheet penetration to the inner magnetosphere under enhanced convection: RCM simulations combined with force-balance magnetic field solver

NASA Astrophysics Data System (ADS)

Gkioulidou, M.; Wang, C.; Lyons, L. R.; Wolf, R. A.

2010-12-01

Transport of plasma sheet particles into the inner magnetosphere is strongly affected by the penetration of the convection electric field, which is the result of the large-scale magnetosphere-ionosphere electromagnetic coupling. This transport, on the other hand, results in plasma heating and magnetic field stretching, which become very significant in the inner plasma sheet (inside 20 RE). We have previously run simulations with the Rice Convection Model (RCM) to investigate how the earthward penetration of convection electric field, and therefore plasma sheet population, depends on plasma sheet boundary conditions. Outer boundary conditions at r ~20 RE are a function of MLT and interplanetary conditions based on 11 years of Geotail data. In the previous simulations, Tsyganenko 96 magnetic field model (T96) was used so force balance between plasma pressure and magnetic fields was not maintained. We have now integrated the RCM with a magnetic field solver (Liu et al., 2006) to obtain the required force balance in the equatorial plane. We have run the self-consistent simulations under enhanced convection with different boundary conditions in which we kept different parameters (flux tube particle content, plasma pressure, plasma beta, or magnetic fields) at the outer boundary to be MLT-dependent but time independent. Different boundary conditions result in qualitatively similar plasma sheet profiles. The results show that magnetic field has a dawn dusk asymmetry with field lines being more stretched in the pre-midnight sector, due to relatively higher plasma pressure there. The asymmetry in the magnetic fields in turn affects the radial distance and MLT of plasma sheet penetration into the inner magnetosphere. In comparison with results using the T96, plasma transport under self-consistent magnetic field results in proton and electron plasma sheet inner edges that are located in higher latitudes, weaker pressure gradients, and more efficient shielding of the near-Earth convection electric field (since auroral conductance is also confined to higher latitudes). We are currently evaluating the simulated plasma sheet properties by comparing them with statistical results obtained from Geotail and THEMIS observations.

Maxwell's theory of eddy currents in thin conducting sheets, and applications to electromagnetic shielding and MAGLEV

NASA Astrophysics Data System (ADS)

Saslow, W. M.

1992-08-01

Using the example of a monopole that is spontaneously generated above a thin conducting sheet, the simplicity and power of Maxwell's 1872 theory of eddy currents in thin conducting sheets is illustrated. This theory employs a receding image construction, with a characteristic recession velocity v0=2/(μ0σd), where the sheet has conductivity σ and thickness d. A modern derivation of the theory, employing the magnetic scalar potential, is also presented, with explicit use of the uniqueness theorem. Also discussed are limitations on the theory of which Maxwell, living in a time before the discovery of the electron, could not have been aware. Previous derivations either have not appealed explicitly to the uniqueness theorem, or have employed the now unfamiliar current function, and are therefore either incomplete or inaccessible to the modern reader. After the derivation, two important examples considered by Maxwell are presented-a monopole moving above a thin conducting sheet, and a monopole above a rotating thin conducting sheet (Arago's disk)-and it is argued that the lift force thus obtained makes Maxwell the grandfather, if not the father, of eddy current MAGLEV transportation systems. An energy conservation argument is given to derive Davis's result that, for a magnet of arbitrary size and shape moving parallel to a thin conducting sheet at a characteristic height h, with velocity v, the ratio of drag force to lift force is equal to v0/v, provided that d≪δc, where δc =√2h/(μ0σv). If d≫δc, the eddy currents are confined to a thickness δc, leading to an increase in the dissipation and the drag by a factor of d/δc, so that the ratio of drag to lift force becomes proportional to √v'0/v, where v'0 = 2/(μ0σh). The case of a monopole fixed in position, but oscillating in strength (such as can be simulated by one end of a long, narrow, ac solenoid), is also treated. This is employed to obtain the results for an oscillating magnetic dipole whose moment is normal to the sheet. A general discussion of electromagnetic induction and electrical conductors, both thick and thin, is given, emphasizing the difference between the high-frequency limit, where flux expulsion occurs and the self-inductance dominates, and the low-frequency limit, where the flux penetrates and the electrical resistance dominates. A discussion of Lenz's law, as a statement about motion, is given. It is argued that the most general form of such a statement of Lenz's law is that induced currents tend to accelerate a conductor in the direction that most effectively decreases the rate of Joule heating. A calculation, in the low-frequency limit, of the drag force on a magnetic dipole falling down a long conducting tube, is also given. This last case can be given a striking demonstration with the newly available neodymium-iron-boron magnets.

The role of acids in electrical conduction through ice

NASA Astrophysics Data System (ADS)

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

2013-03-01

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

Method for transferring thermal energy and electrical current in thin-film electrochemical cells

DOEpatents

Rouillard, Roger [Beloeil, CA; Domroese, Michael K [South St. Paul, MN; Hoffman, Joseph A [Minneapolis, MN; Lindeman, David D [Hudson, WI; Noel, Joseph-Robert-Gaetan [St-Hubert, CA; Radewald, Vern E [Austin, TX; Ranger, Michel [Lachine, CA; Sudano, Anthony [Laval, CA; Trice, Jennifer L [Eagan, MN; Turgeon, Thomas A [Fridley, MN

2003-05-27

An improved electrochemical generator is disclosed. The electrochemical generator includes a thin-film electrochemical cell which is maintained in a state of compression through use of an internal or an external pressure apparatus. A thermal conductor, which is connected to at least one of the positive or negative contacts of the cell, conducts current into and out of the cell and also conducts thermal energy between the cell and thermally conductive, electrically resistive material disposed on a vessel wall adjacent the conductor. The thermally conductive, electrically resistive material may include an anodized coating or a thin sheet of a plastic, mineral-based material or conductive polymer material. The thermal conductor is fabricated to include a resilient portion which expands and contracts to maintain mechanical contact between the cell and the thermally conductive material in the presence of relative movement between the cell and the wall structure. The electrochemical generator may be disposed in a hermetically sealed housing.

Thin-Film Nanowire Networks for Transparent Conductor Applications: Simulations of Sheet Resistance and Percolation Thresholds

NASA Astrophysics Data System (ADS)

Winey, Karen I.; Mutiso, Rose M.; Sherrott, Michelle C.; Rathmell, Aaron R.; Wiley, Benjamin J.

2013-03-01

Thin-film metal nanowire networks are being pursued as a viable alternative to the expensive and brittle indium tin oxide (ITO) for transparent conductors. For high performance applications, nanowire networks must exhibit high transmittance at low sheet resistance. Previously, we have used complimentary experimental, simulation and theoretical techniques to explore the effects of filler aspect ratio (L/D), orientation, and size-dispersity on the electrical conductivity of three-dimensional rod-networks in bulk polymer nanocomposites. We adapted our 3D simulation approach and analytical percolation model to study the electrical properties of thin-film rod-networks. By fitting our simulation results to experimental results, we determined the average effective contact resistance between silver nanowires. This contact resistance was then used to quantify how the sheet resistance depends on the aspect ratio of the rods and to show that networks made of nanowires with L/D greater than 100 yield sheet resistances lower than the required 100 Ohm/sq. We also report the critical area fraction of rods required to form a percolated network in thin-film networks and provide an analytical expression for the critical area fraction as a function of L/D.

Fabrication of a transparent conducting electrode based on graphene/silver nanowires via layer-by-layer method for organic photovoltaic devices.

PubMed

Tugba Camic, B; Oytun, Faruk; Hasan Aslan, M; Jeong Shin, Hee; Choi, Hyosung; Basarir, Fevzihan

2017-11-01

A solution-processed transparent conducting electrode was fabricated via layer-by-layer (LBL) deposition of graphene oxide (GO) and silver nanowires (Ag NWs). First, graphite was oxidized with a modified Hummer's method to obtain negatively-charged GO sheets, and Ag NWs were functionalized with cysteamine hydrochloride to acquire positively-charged silver nanowires. Oppositely-charged GO and Ag NWs were then sequentially coated on a 3-aminopropyltriethoxysilane modified glass substrate via LBL deposition, which provided highly controllable thin films in terms of optical transmittance and sheet resistance. Next, the reduction of GO sheets was performed to improve the electrical conductivity of the multilayer films. The resulting GO/Ag NWs multilayer was characterized by a UV-Vis spectrometer, field emission scanning electron microscope (FE-SEM), optical microscope (OM) and sheet resistance using a four-point probe method. The best result was achieved with a 2-bilayer film, resulting in a sheet resistance of 6.5Ω sq -1 with an optical transmittance of 78.2% at 550nm, which values are comparable to those of commercial ITO electrodes. The device based on a 2-bilayer hybrid film exhibited the highest device efficiency of 1.30% among the devices with different number of graphene/Ag NW LBL depositions. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

NASA Astrophysics Data System (ADS)

Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

2016-06-01

The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

Tunable electronic, electrical and optical properties of graphene oxide sheets by ion irradiation

NASA Astrophysics Data System (ADS)

Jayalakshmi, G.; Saravanan, K.; Panigrahi, B. K.; Sundaravel, B.; Gupta, Mukul

2018-05-01

The tunable electronic, electrical and optical properties of graphene oxide (GO) sheets were investigated using a controlled reduction by 500 keV Ar+-ion irradiation. The carbon to oxygen ratio of the GO sheets upon the ion beam reduction has been estimated using resonant Rutherford backscattering spectrometry analyses and its effect on the electrical and optical properties of GO sheets has been studied using sheet resistance measurements and photoluminescence (PL) measurements. The restoration of sp 2-hybridized carbon atoms within the sp 3 matrix is found to be increases with increasing the Ar+-ion fluences as evident from Fourier transform infrared, and x-ray absorption near-edge structure measurements. The decrease in the number of disorder-induced local density of states (LDOSs) within the π-π* gap upon the reduction causes the shifting of PL emission from near infra-red to blue region and decreases the sheet resistance. The improved electrical and optical properties of GO sheets were correlated to the decrease in the number of LDOSs within the π-π* gap. Our experimental investigations suggest ion beam irradiation is one of an effective approaches to reduce GO to RGO and to tailor its electronic, electrical and optical properties.

Tunable electronic, electrical and optical properties of graphene oxide sheets by ion irradiation.

PubMed

Jayalakshmi, G; Saravanan, K; Panigrahi, B K; Sundaravel, B; Gupta, Mukul

2018-05-04

The tunable electronic, electrical and optical properties of graphene oxide (GO) sheets were investigated using a controlled reduction by 500 keV Ar + -ion irradiation. The carbon to oxygen ratio of the GO sheets upon the ion beam reduction has been estimated using resonant Rutherford backscattering spectrometry analyses and its effect on the electrical and optical properties of GO sheets has been studied using sheet resistance measurements and photoluminescence (PL) measurements. The restoration of sp 2 -hybridized carbon atoms within the sp 3 matrix is found to be increases with increasing the Ar + -ion fluences as evident from Fourier transform infrared, and x-ray absorption near-edge structure measurements. The decrease in the number of disorder-induced local density of states (LDOSs) within the π-π* gap upon the reduction causes the shifting of PL emission from near infra-red to blue region and decreases the sheet resistance. The improved electrical and optical properties of GO sheets were correlated to the decrease in the number of LDOSs within the π-π* gap. Our experimental investigations suggest ion beam irradiation is one of an effective approaches to reduce GO to RGO and to tailor its electronic, electrical and optical properties.

Graphite-based photovoltaic cells

DOEpatents

Lagally, Max; Liu, Feng

2010-12-28

The present invention uses lithographically patterned graphite stacks as the basic building elements of an efficient and economical photovoltaic cell. The basic design of the graphite-based photovoltaic cells includes a plurality of spatially separated graphite stacks, each comprising a plurality of vertically stacked, semiconducting graphene sheets (carbon nanoribbons) bridging electrically conductive contacts.

Graphene Oxide Papers Simultaneously Doped with Mg(2+) and Cl(-) for Exceptional Mechanical, Electrical, and Dielectric Properties.

PubMed

Lin, Xiuyi; Shen, Xi; Sun, Xinying; Liu, Xu; Wu, Ying; Wang, Zhenyu; Kim, Jang-Kyo

2016-01-27

This paper reports simultaneous modification of graphene oxide (GO) papers by functionalization with MgCl2. The Mg(2+) ions enhance both the interlayer cross-links and lateral bridging between the edges of adjacent GO sheets by forming Mg-O bonds. The improved load transfer between the GO sheets gives rise to a maximum of 200 and 400% increases in Young's modulus and tensile strength of GO papers. The intercalation of chlorine between the GO layers alters the properties of GO papers in two ways by forming ionic Cl(-) and covalent C-Cl bonds. The p-doping effect arising from Cl contributes to large enhancements in electrical conductivities of GO papers, with a remarkable 2500-fold surge in the through-thickness direction. The layered structure and the anisotropic electrical conductivities of reduced GO papers naturally create numerous nanocapacitors that lead to charge accumulation based on the Maxwell-Wagner (MW) polarization. The combined effect of much promoted dipolar polarizations due to Mg-O, C-Cl, and Cl(-) species results in an exceptionally high dielectric constant greater than 60 000 and a dielectric loss of 3 at 1 kHz by doping with 2 mM MgCl2. The excellent mechanical and electrical properties along with unique dielectric performance shown by the modified GO and rGO papers open new avenues for niche applications, such as electromagnetic interference shielding materials.

An integrated surface-geophysical investigation of the University of Connecticut landfill, Storrs, Connecticut, 2000

USGS Publications Warehouse

Johnson, Carole D.; Dawson, C.B.; Belaval, Marcel; Lane, John W.

2002-01-01

A surface-geophysical investigation to characterize the hydrogeology and contaminant distribution of the former landfill area at the University of Connecticut in Storrs, Connecticut, was conducted in 2000 to supplement the preliminary hydrogeologic assessment of the contamination of soil, surface water, and ground water at the site. A geophysical-toolbox approach was used to characterize the hydrogeology and contaminant distribution of the former landfill. Two-dimensional direct-current resistivity, inductive terrain-conductivity, and seismic-refraction surface-geophysical data were collected and interpreted in an iterative manner with exploratory drilling, borehole geophysics, and hydraulic testing. In this investigation, a geophysical-toolbox approach was used to 1) further define previously identified conductive anomalies and leachate plumes; 2) identify additional leachate plumes, possible fracture zones, and (or) conductive lithologic layers in the bedrock; and 3) delineate bedrock-surface topography in the drainage valleys north and south of the landfill. Resistivity and terrain-conductivity surveys were used to further delineate previously identified geophysical anomalies to the north and southwest of the landfill. A conductive anomaly identified in the terrain-conductivity survey to the north of the landfill in 2000 had a similar location and magnitude as an anomaly identified in terrain-conductivity surveys conducted in 1998 and 1999. Collectively, these surveys indicated that the magnitude of the conductive anomaly decreased with depth and with distance from the landfill. These anomalies indicated landfill leachate in the overburden and shallow bedrock. Results of previous surface-geophysical investigations southwest of the landfill indicated a shallow conductive anomaly in the overburden that extended into the fractured-bedrock aquifer. This conductive anomaly had a sheet-like geometry that had a north-south strike, dipped to the west, and terminated abruptly about 450 feet southwest of the landfill. The sheet-like conductive anomaly was interpreted as a fractured, conductive lithologic feature filled with conductive fluids. To further delineate this anomaly, two two-dimensional resistivity profiles were collected west of the sheet-like conductive anomaly to assess the possibility that the sheet-like conductive anomaly continued to the west in its down-dip direction. Each of the north-south oriented resistivity profiles showed bullet-shaped rather than linear-shaped anomalies, with a relatively smaller magnitude of conductivity than the sheet-like conductive anomaly to the east. If these bullet-like features are spatially connected, they may represent a linear, or pipe-like, conductive anomaly in the bedrock with a trend of N290?E and a plunge of 12?. Additional surveys were conducted to assess the apparent southern termination of the sheet-like conductive feature. Terrain-conductivity surveys indicated the sheet-like feature was not continuous to the south. A two-dimensional resistivity line and a coincident terrain-conductivity profile indicated the presence of a steep, eastward dipping, low magnitude, electrically conductive anomaly on the eastern end of the profile. Although the sheet-like conductive anomaly apparently did not continue to the south, the survey conducted in 2000 identified an isolated, weak conductive anomaly south of the previously identified anomaly. Inductive terrain-conductivity surveys performed north of the sheet-like conductive anomaly and west of the landfill indicated the anomaly did not extend to the north into the area of the former chemical-waste disposal pits. No conductive plumes or conductive features were observed in the subsurface bedrock west of the landfill. A conductive anomaly was identified in the southern section of the new terrain-conductivity grid. The magnitude and distribution of the apparent conductivity of this anomaly was identified as a nearly vertica

Electrical conductivity of In2O3 and Ga2O3 after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level.

PubMed

Vines, L; Bhoodoo, C; von Wenckstern, H; Grundmann, M

2017-12-13

The evolution of sheet resistance of n-type In 2 O 3 and Ga 2 O 3 exposed to bombardment with MeV 12 C and 28 Si ions at 35 K is studied in situ. While the sheet resistance of Ga 2 O 3 increased by more than eight orders of magnitude as a result of ion irradiation, In 2 O 3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga 2 O 3 remained highly resistive, while In 2 O 3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to [Formula: see text] cm -2 . A model where larger defect complexes preferentially produce donor like defects in In 2 O 3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed.

Electrical conductivity of In2O3 and Ga2O3 after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level

NASA Astrophysics Data System (ADS)

Vines, L.; Bhoodoo, C.; von Wenckstern, H.; Grundmann, M.

2018-01-01

The evolution of sheet resistance of n-type In2O3 and Ga2O3 exposed to bombardment with MeV 12C and 28Si ions at 35 K is studied in situ. While the sheet resistance of Ga2O3 increased by more than eight orders of magnitude as a result of ion irradiation, In2O3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga2O3 remained highly resistive, while In2O3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to 2 × 1012 cm-2. A model where larger defect complexes preferentially produce donor like defects in In2O3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed.

Detail of north end of the Electrical Shop (foreground) and ...

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

Detail of north end of the Electrical Shop (foreground) and Sheet Metal Shop, note the metal-frame windows in the Electrical Shop, view facing east - Kahului Cannery, Plant No. 28, Boiler House, Sheet Metal and Electrical Shops, 120 Kane Street, Kahului, Maui County, HI

Electrical-assisted double side incremental forming and processes thereof

DOEpatents

Roth, John; Cao, Jian

2014-06-03

A process for forming a sheet metal component using an electric current passing through the component is provided. The process can include providing a double side incremental forming machine, the machine operable to perform a plurality of double side incremental deformations on the sheet metal component and also apply an electric direct current to the sheet metal component during at least part of the forming. The direct current can be applied before or after the forming has started and/or be terminated before or after the forming has stopped. The direct current can be applied to any portion of the sheet metal. The electrical assistance can reduce the magnitude of force required to produce a given amount of deformation, increase the amount of deformation exhibited before failure and/or reduce any springback typically exhibited by the sheet metal component.

Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Composites

NASA Technical Reports Server (NTRS)

Kang, Jin Ho; Cano, Roberto J.; Ratcliffe, James G.; Luong, Hoa; Grimsley, Brian W.; Siochi, Emilie J.

2016-01-01

For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strengthand stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Despite several attempts to solve these issues with the addition of carbon nanotubes (CNT) into polymer matrices, and/or by interleaving CNT sheets between conventional carbon fiber (CF) composite layers, there are still interfacial problems that exist between CNTs (or CF) and the resin. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing (double cantilever beam and end-notched flexure test). Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated. Interleaving CNT sheets significantly improved the in-plane (axial and perpendicular direction of CF alignment) thermal conductivity of the hybrid composite laminates by 50 - 400%.

Effect of an MLT dependent electron loss rate on the magnetosphere-ionosphere coupling

NASA Astrophysics Data System (ADS)

Gkioulidou, Matina; Wang, Chih-Ping; Wing, Simon; Lyons, Larry R.; Wolf, Richard A.; Hsu, Tung-Shin

2012-11-01

As plasma sheet electrons drift earthward, they get scattered into the loss cone due to wave-particle interactions and the resulting precipitation produces auroral conductance. Realistic electron loss is thus important for modeling the magnetosphere - ionosphere (M-I) coupling and the degree of plasma sheet electron penetration into the inner magnetosphere. In order to evaluate the significance of electron loss, we used the Rice Convection Model (RCM) coupled with a force-balanced magnetic field to simulate plasma sheet transport under different electron loss rates and under self-consistent electric and magnetic field. We used different magnitudes of i) strong pitch angle diffusion everywhere electron loss rate (strong rate) and ii) a more realistic loss rate with its MLT dependence determined by wave activity (MLT rate). We found that electron pressure under the MLT rate is larger compared to the strong rate inside L ∼ 12 RE. The dawn-dusk asymmetry in the precipitating electron energy flux under the MLT rate, with much higher energy flux at dawn than at dusk, agrees better with statistical DMSP observations. High-energy electrons inside L ∼ 8 RE can remain there for many hours under the MLT rate, while those under the strong rate get lost within minutes. Under the MLT rate, the remaining electrons cause higher conductance at lower latitudes; thus after a convection enhancement, the shielding of the convection electric field is less efficient, and as a result, the ion plasma sheet penetrates further earthward into the inner magnetosphere than under the strong rate.

Electrical Oscillations in Two-Dimensional Microtubular Structures

PubMed Central

Cantero, María del Rocío; Perez, Paula L.; Smoler, Mariano; Villa Etchegoyen, Cecilia; Cantiello, Horacio F.

2016-01-01

Microtubules (MTs) are unique components of the cytoskeleton formed by hollow cylindrical structures of αβ tubulin dimeric units. The structural wall of the MT is interspersed by nanopores formed by the lateral arrangement of its subunits. MTs are also highly charged polar polyelectrolytes, capable of amplifying electrical signals. The actual nature of these electrodynamic capabilities remains largely unknown. Herein we applied the patch clamp technique to two-dimensional MT sheets, to characterize their electrical properties. Voltage-clamped MT sheets generated cation-selective oscillatory electrical currents whose magnitude depended on both the holding potential, and ionic strength and composition. The oscillations progressed through various modes including single and double periodic regimes and more complex behaviours, being prominent a fundamental frequency at 29 Hz. In physiological K+ (140 mM), oscillations represented in average a 640% change in conductance that was also affected by the prevalent anion. Current injection induced voltage oscillations, thus showing excitability akin with action potentials. The electrical oscillations were entirely blocked by taxol, with pseudo Michaelis-Menten kinetics and a KD of ~1.29 μM. The findings suggest a functional role of the nanopores in the MT wall on the genesis of electrical oscillations that offer new insights into the nonlinear behaviour of the cytoskeleton. PMID:27256791

Method and apparatus for capacitive deionization and electrochemical purification and regeneration of electrodes

DOEpatents

Farmer, Joseph C.

1999-01-01

An electrically regeneratable electrochemical cell (30) for capacitive deionization and electrochemical purification and regeneration of electrodes includes two end plates (31, 32), one at each end of the cell (30). Two end electrodes (35, 36) are arranged one at each end of the cell (30), adjacent to the end plates (31, 32). An insulator layer (33) is interposed between each end plate (31, 32) and the adjacent end electrode (35, 36). Each end electrode (35, 36) includes a single sheet (44) of conductive material having a high specific surface area and sorption capacity. In one embodiment, the sheet (44) of conductive material is formed of carbon aerogel composite. The cell (30) further includes a plurality of generally identical double-sided intermediate electrodes (37-43) that are equidistally separated from each other, between the two end electrodes (35, 36). As the electrolyte enters the cell, it flows through a continuous open serpentine channel (65-71) defined by the electrodes, substantially parallel to the surfaces of the electrodes. By polarizing the cell (30), ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the cell (30) is saturated with the removed ions, the cell (30) is regenerated electrically, thus significantly minimizing secondary wastes.

Electrical transport properties of spray deposited transparent conducting ortho-Zn2SnO4 thin films

NASA Astrophysics Data System (ADS)

Ramarajan, R.; Thangaraju, K.; Babu, R. Ramesh; Joseph, D. Paul

2018-04-01

Ortho Zinc Stannate (Zn2SnO4) exhibits excellent electrical and optical properties to serve as alternate transparent electrode in optoelectronic devices. Here we have optimized ortho-Zn2SnO4 thin film by spray pyrolysis method. Deposition was done onto a pre-heated glass substrate at a temperature of 400 °C. The XRD pattern indicated films to be polycrystalline with cubic structure. The surface of films had globular and twisted metal sheet like morphologies. Films were transparent in the visible region with band gap around 3.6 eV. Transport properties were studied by Hall measurements at 300 K. Activation energies were calculated from Arrhenius's plot from temperature dependent electrical measurements and the conduction mechanism is discussed.

Electromagnetically Clean Solar Arrays

NASA Technical Reports Server (NTRS)

Stem, Theodore G.; Kenniston, Anthony E.

2008-01-01

The term 'electromagnetically clean solar array' ('EMCSA') refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interferences to and from other nearby electrical and electronic equipment and (2) can be manufactured at lower cost. The reduction of electromagnetic interferences is effected through a combination of (1) electrically conductive, electrically grounded shielding and (2) reduction of areas of current loops (in order to reduce magnetic moments). The reduction of cost is effected by designing the array to be fabricated as a more nearly unitary structure, using fewer components and fewer process steps. Although EMCSAs were conceived primarily for use on spacecraft they are also potentially advantageous for terrestrial applications in which there are requirements to limit electromagnetic interference. In a conventional solar panel of the type meant to be supplanted by an EMCSA panel, the wiring is normally located on the back side, separated from the cells, thereby giving rise to current loops having significant areas and, consequently, significant magnetic moments. Current-loop geometries are chosen in an effort to balance opposing magnetic moments to limit far-0field magnetic interactions, but the relatively large distances separating current loops makes full cancellation of magnetic fields problematic. The panel is assembled from bare photovoltaic cells by means of multiple sensitive process steps that contribute significantly to cost, especially if electomagnetic cleanliness is desired. The steps include applying a cover glass and electrical-interconnect-cell (CIC) sub-assemble, connecting the CIC subassemblies into strings of series-connected cells, laying down and adhesively bonding the strings onto a panel structure that has been made in a separate multi-step process, and mounting the wiring on the back of the panel. Each step increases the potential for occurrence of latent defects, loss of process control, and attrition of components. An EMCSA panel includes an integral cover made from a transparent material. The silicone cover supplants the individual cover glasses on the cells and serves as an additional unitary structural support that offers the advantage, relative to glass, of the robust, forgiving nature of the silcone material. The cover contains pockets that hold the solar cells in place during the lamination process. The cover is coated with indium tin oxide to make its surface electrically conductive, so that it serves as a contiguous, electrically grounded shield over the entire panel surface. The cells are mounted in proximity to metallic printed wiring. The painted-wiring layer comprises metal-film traces on a sheet of Kapton (or equivalent) polyimide. The traces include contact pads on one side of the sheet for interconnecting the cells. Return leads are on the opposite side of the sheet, positioned to form the return currents substantially as mirror images of, and in proximity to, the cell sheet currents, thereby minimizing magnetic moments. The printed-wiring arrangement mimics the back-wiring arrangement of conventional solar arrays, but the current-loop areas and the resulting magnetic moments are much smaller because the return-current paths are much closer to the solar-cell sheet currents. The contact pads are prepared with solder fo electrical and mechanical bonding to the cells. The pocketed cover/shield, the solar cells, the printed-wiring layer, an electrical bonding agent, a mechanical-bonding agent, a composite structural front-side face sheet, an aluminum honeycomb core, and a composite back-side face sheet are all assembled, then contact pads are soldered to the cells and the agents are cured in a single lamination process.

Ultrasoft Electronics for Hyperelastic Strain, Pressure, and Direct Curvature Sensing

NASA Astrophysics Data System (ADS)

Majidi, Carmel; Kramer, Rebecca; Wood, Robert

2011-03-01

Progress in soft robotics, wearable computing, and programmable matter demands a new class of ultrasoft electronics for tactile control, contact detection, and deformation mapping. This next generation of sensors will remain electrically functional under extreme deformation without influencing the natural mechanics of the host system. Ultrasoft strain and pressure sensing has previously been demonstrated with elastomer sheets (eg. PDMS, silicone rubber) embedded with microchannels of conductive liquid (mercury, eGaIn). Building on these efforts, we introduce a novel method for direct curvature sensing that registers the location and intensity of surface curvature. An elastomer sheet is embedded with micropatterned cavities and microchannels of conductive liquid. Bending the elastomer or placing it on a curved surface leads to a change in channel cross-section and a corresponding change in its electrical resistance. In contrast to conventional methods of curvature sensing, this approach does not depend on semi-rigid components or differential strain measurement. Direct curvature sensing completes the portfolio of sensing elements required to completely map hyperelastic deformation for future soft robotics and computing. NSF MRSEC DMR-0820484.

Study of simultaneous reduction and nitrogen doping of graphene oxide Langmuir-Blodgett monolayer sheets by ammonia plasma treatment

NASA Astrophysics Data System (ADS)

Singh, Gulbagh; Sutar, D. S.; Divakar Botcha, V.; Narayanam, Pavan K.; Talwar, S. S.; Srinivasa, R. S.; Major, S. S.

2013-09-01

Graphene oxide (GO) monolayer sheets, transferred onto Si by the Langmuir-Blodgett technique, were subjected to ammonia plasma treatment at room temperature with the objective of simultaneous reduction and doping. Scanning electron microscopy and atomic force microscopy studies show that plasma treatment at a relatively low power (˜10 W) for up to 15 min does not affect the morphological stability and monolayer character of GO sheets. X-ray photoelectron spectroscopy has been used to study de-oxygenation of GO monolayers and the incorporation of nitrogen in graphitic-N, pyrrolic-N and pyridinic-N forms due to the plasma treatment. The corresponding changes in the valence band electronic structure, density of states at the Fermi level and work function have been investigated by ultraviolet photoelectron spectroscopy. These studies, supported by Raman spectroscopy and electrical conductivity measurements, have shown that a short duration plasma treatment of up to 5 min results in an increase of sp2-C content along with a substantial incorporation of the graphitic-N form, leading to the formation of n-type reduced GO. Prolonged plasma treatment for longer durations results in a decrease of electrical conductivity, which is accompanied by a substantial decrease of sp2-C and an increase in defects and disorder, primarily attributed to the increase in pyridinic-N content.

A comparative DFT study on the interaction of cathinone drug with BN nanotubes, nanocages, and nanosheets

NASA Astrophysics Data System (ADS)

Nejati, Kamellia; Hosseinian, Akram; Vessally, Esmail; Bekhradnia, Ahmadreza; Edjlali, Ladan

2017-11-01

Cathinone is an organic stimulant which is classified as psychoactive drug and its abuse has been linked to many deaths worldwide. Here, we studied the electronic sensitivity of a BN cage, a zigzag (6, 0) BN nanotube, and a BN nanosheet toward cathinone using density functional theory calculations. The B3LYP-D functional predicts that the order of magnitude of electrical conductivity of BN nanostructures is as follows tube > sheet > cage. The cathinone drug prefers to be adsorbed on the BN nanostructures via its sbnd NH2 group rather than O-head with adsorption energy about -16.1, -14.0 and -5.0 kcal/mol for cage, tube, and sheet, respectively. Our results indicate that by increasing the p-character of the hybridization of the adsorbing B atom in the BN nanostructures, the interaction is strengthened. Based on the density of states analysis, it was demonstrated that the electrical conductivity of the BN nanostructures is decreased by the drug adsorption, indicating that they can be used in the cathinone sensors. The order of magnitude of the sensitivity is as follows: SCage > STube > SSheet. This trend corresponds to the decrease of the structural curvature in the BN nanostructures. Finally, a short recovery time of about 0.54 s, 0.02 s and 4.4 ns is predicted for cage, tube and sheet, respectively, at 298 K.

Modified Unzipping Technique to Prepare Graphene Nano-Sheets

NASA Astrophysics Data System (ADS)

Al-Tamimi, B. H.; Farid, S. B. H.; Chyad, F. A.

2018-05-01

Graphene nano-sheets have been prepared via unzipping approach of multiwall carbon nanotubes (MWCNTs). The method includes two chemical-steps, in which a multi-parameter oxidation step is performed to achieve unzipping the carbon nanotubes. Then, a reduction step is carried out to achieve the final graphene nano-sheets. In the oxidation step, the oxidant material was minimized and balanced with longer curing time. This modification is made in order to reduce the oxygen-functional groups at the ends of graphene basal planes, which reduce its electrical conductivity. In addition, a similar adjustment is achieved in the reduction step, i.e. the consumed chemicals is reduced which make the overall process more economic and eco-friendly. The prepared nano-sheets were characterized by atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. The average thickness of the prepared graphene was about 5.23 nm.

Rechargeable thin-film electrochemical generator

DOEpatents

Rouillard, Roger; Domroese, Michael K.; Hoffman, Joseph A.; Lindeman, David D.; Noel, Joseph-Robert-Gaetan; Radewald, Vern E.; Ranger, Michel; Sudano, Anthony; Trice, Jennifer L.; Turgeon, Thomas A.

2000-09-15

An improved electrochemical generator is disclosed. The electrochemical generator includes a thin-film electrochemical cell which is maintained in a state of compression through use of an internal or an external pressure apparatus. A thermal conductor, which is connected to at least one of the positive or negative contacts of the cell, conducts current into and out of the cell and also conducts thermal energy between the cell and thermally conductive, electrically resistive material disposed on a vessel wall adjacent the conductor. The thermally conductive, electrically resistive material may include an anodized coating or a thin sheet of a plastic, mineral-based material or conductive polymer material. The thermal conductor is fabricated to include a resilient portion which expands and contracts to maintain mechanical contact between the cell and the thermally conductive material in the presence of relative movement between the cell and the wall structure. The electrochemical generator may be disposed in a hermetically sealed housing.

Evaluation of conductive concrete for anti-static flooring applications

NASA Astrophysics Data System (ADS)

Yehia, Sherif; Qaddoumi, Nasser; Hassan, Mohamed; Swaked, Bassam

2015-04-01

Static electricity, exchange of electrons, and retention of charge between any two materials due to contact and separation are affected by the condition of the materials being nonconductive or insulated from ground. Several work environments, such as electronics industry, hospitals, offices, and computer rooms all require electro-static discharge (ESD) mitigation. Carpet Tile, Carpet Broadloom, Vinyl Tile, Vinyl sheet, Epoxy and Rubber are examples of existing flooring systems in the market. However, each system has its advantages and limitations. Conductive concrete is a relatively new material technology developed to achieve high electrical conductivity and high mechanical strength. The conductive concrete material can be an economical alternative for these ESD flooring systems. In this paper, the effectiveness of conductive concrete as an anti-static flooring system was evaluated. The initial results indicated that the proposed conductive concrete flooring and ground system met the acceptance criteria stated by ASTM F150.

Platinum-decorated reduced graphene oxide/polyaniline:poly(4-styrenesulfonate) hybrid paste for flexible dipole tag-antenna applications

NASA Astrophysics Data System (ADS)

Lee, Jun Seop; Kim, Minkyu; Lee, Choonghyeon; Cho, Sunghun; Oh, Jungkyun; Jang, Jyongsik

2015-02-01

With recent developments in technology, tremendous effort has been devoted to producing materials for flexible device systems. As a promising approach, solution-processed conducting polymers (CPs) have been extensively studied owing to their facile synthesis, high electrical conductivity, and various morphologies with diverse substrates. Here, we report the demonstration of platinum decorated reduced graphene oxide intercalated polyanililne:poly(4-styrenesulfonate) (Pt_rGO/PANI:PSS) hybrid paste for flexible electric devices. First, platinum decorated reduced graphene oxide (Pt_rGO) was fabricated through the chemical reduction of platinum cations and subsequent heat reduction of GO sheets. Then, the Pt_rGO was mixed with PANI:PSS solution dispersed in diethylene glycol (DEG) using sonication to form a hybrid PANI-based paste (Pt_rGO/PANI:PSS). The Pt_rGO/PANI:PSS was printed as a micropattern and exhibited high electrical conductivity (245.3 S cm-1) with flexible stability. Moreover, it was used in a dipole tag antenna application, where it displayed 0.15 GHz bandwidth and high transmitted power efficiency (99.6%).With recent developments in technology, tremendous effort has been devoted to producing materials for flexible device systems. As a promising approach, solution-processed conducting polymers (CPs) have been extensively studied owing to their facile synthesis, high electrical conductivity, and various morphologies with diverse substrates. Here, we report the demonstration of platinum decorated reduced graphene oxide intercalated polyanililne:poly(4-styrenesulfonate) (Pt_rGO/PANI:PSS) hybrid paste for flexible electric devices. First, platinum decorated reduced graphene oxide (Pt_rGO) was fabricated through the chemical reduction of platinum cations and subsequent heat reduction of GO sheets. Then, the Pt_rGO was mixed with PANI:PSS solution dispersed in diethylene glycol (DEG) using sonication to form a hybrid PANI-based paste (Pt_rGO/PANI:PSS). The Pt_rGO/PANI:PSS was printed as a micropattern and exhibited high electrical conductivity (245.3 S cm-1) with flexible stability. Moreover, it was used in a dipole tag antenna application, where it displayed 0.15 GHz bandwidth and high transmitted power efficiency (99.6%). Electronic supplementary information (ESI) available: TEM images of Pr_rGOs, XRD spectra of various PANI-based hybrid materials, electrical conductivity of Pt_rGO/PANI:PSS with different Pt amounts, surface resistance changes of micropatterns, return loss of the antenna with bending deformation, and transmitted power efficiency of the antenna with bending cycles. See DOI: 10.1039/c4nr06189f

Substorm Electric And Magnetic Fields In The Earth's Magnetotail: Observations Compared To The WINDMI Model

NASA Astrophysics Data System (ADS)

Srinivas, P. G.; Spencer, E. A.; Vadepu, S. K.; Horton, W., Jr.

2017-12-01

We compare satellite observations of substorm electric fields and magnetic fields to the output of a low dimensional nonlinear physics model of the nightside magnetosphere called WINDMI. The electric and magnetic field satellite data are used to calculate the E X B drift, which is one of the intermediate variables of the WINDMI model. The model uses solar wind and IMF measurements from the ACE spacecraft as input into a system of 8 nonlinear ordinary differential equations. The state variables of the differential equations represent the energy stored in the geomagnetic tail, central plasma sheet, ring current and field aligned currents. The output from the model is the ground based geomagnetic westward auroral electrojet (AL) index, and the Dst index.Using ACE solar wind data, IMF data and SuperMAG identification of substorm onset times up to December 2015, we constrain the WINDMI model to trigger substorm events, and compare the model intermediate variables to THEMIS and GEOTAIL satellite data in the magnetotail. By forcing the model to be consistent with satellite electric and magnetic field observations, we are able to track the magnetotail energy dynamics, the field aligned current contributions, energy injections into the ring current, and ensure that they are within allowable limts. In addition we are able to constrain the physical parameters of the model, in particular the lobe inductance, the plasma sheet capacitance, and the resistive and conductive parameters in the plasma sheet and ionosphere.

Hydrothermal synthesis of mesoporous VO{sub 2}·½(H{sub 2}O) nanosheets and study of their electrical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soltane, L.; Sediri, F., E-mail: faouzi.sediri@ipeit.rnu.tn; Faculté des Sciences de Tunis, Université, Tunis-Elmanar, 2092 Elmanar, Tunis

Highlights: ► Sheet-like nanocrystalline VO{sub 2}·½(H{sub 2}O) was synthesized by a hydrothermal route. ► Reaction time is key factor for structure and morphology. ► Electrical properties were also studied. ► Conductivity value goes from 75 10{sup −6} Ω{sup −1} cm{sup −1} at 298 K to 68 10{sup −5} Ω{sup −1} cm{sup −1} at 386 K. -- Abstract: Layered sheet-like nanocrystalline VO{sub 2}·½(H{sub 2}O) has been synthesized by hydrothermal process using V{sub 2}O{sub 5} as vanadium source and 2-phenylethylamine as a reducing agent and a structure-directing template. Techniques X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformmore » infrared spectroscopy (FTIR) and nitrogen adsorption/desorption isotherms have been used to characterize the structure, morphology and composition of the materials. Electrical conductivity measurements showed that the as synthesized VO{sub 2}·½(H{sub 2}O) nanosheets has a conductivity value which goes from 75 × 10{sup −6} Ω{sup −1} cm{sup −1} at 298 K, to 68 10{sup −5} Ω{sup −1} cm{sup −1} at 386 K with activation energy of 0.24 eV.« less

The Effects of Thermal Radiation on an Unsteady MHD Axisymmetric Stagnation-Point Flow over a Shrinking Sheet in Presence of Temperature Dependent Thermal Conductivity with Navier Slip

PubMed Central

Mondal, Sabyasachi; Haroun, Nageeb A. H.; Sibanda, Precious

2015-01-01

In this paper, the magnetohydrodynamic (MHD) axisymmetric stagnation-point flow of an unsteady and electrically conducting incompressible viscous fluid in with temperature dependent thermal conductivity, thermal radiation and Navier slip is investigated. The flow is due to a shrinking surface that is shrunk axisymmetrically in its own plane with a linear velocity. The magnetic field is imposed normally to the sheet. The model equations that describe this fluid flow are solved by using the spectral relaxation method. Here, heat transfer processes are discussed for two different types of wall heating; (a) a prescribed surface temperature and (b) a prescribed surface heat flux. We discuss and evaluate how the various parameters affect the fluid flow, heat transfer and the temperature field with the aid of different graphical presentations and tabulated results. PMID:26414006

Preparation of conductive paper composites based on natural cellulosic fibers for packaging applications.

PubMed

Youssef, Ahmed M; El-Samahy, Magda Ali; Abdel Rehim, Mona H

2012-08-01

Conducting paper based on natural cellulosic fibers and conductive polymers was prepared using unbleached bagasse and/or rice straw fibers (as cellulosic raw materials) and polyaniline (PANi) as conducting polymer. These composites were synthesized by in situ emulsion polymerization using ammonium persulfate (APS) as oxidant in the presence of dodecylbenzene sulfonic acid (DBSA) as emulsifier. The prepared composites were characterized using Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimeter (DSC), and their morphology was investigated using scanning electron microscope (SEM). Electrical conductivity measurements showed that the conductivity of the paper sheets increases by increasing the ratio of PANi in the composite. Mechanical properties of the paper sheets were also investigated, the results revealed that the values of breaking length, burst factor, and tear factor are decreased with increasing ratio of added PANi, and this effect is more pronounced in bagasse-based composites. The new conductive composites can have potential use as anti-static packaging material or anti-bacterial paper for packaging applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Conductivity enhancement of surface-polymerized polyaniline films via control of processing conditions

NASA Astrophysics Data System (ADS)

Park, Chung Hyoi; Jang, Sung Kyu; Kim, Felix Sunjoo

2018-01-01

We investigate a fast and facile approach for the simultaneous synthesis and coating of conducting polyaniline (PANI) onto a substrate and the effects of processing conditions on the electrical properties of the fabricated films. Simultaneous polymerizing and depositing on the substrate forms a thin film with the average thickness of 300 nm and sheet resistance of 304 Ω/sq. Deposition conditions such as polymerization time (3-240 min), temperature (-10 to 40 °C), concentrations of monomer and oxidant (0.1-0.9 M), and type of washing solvents (acetone, water, and/or HCl solution) affect the film thickness, doping state, absorption characteristics, and solid-state nanoscale morphology, therefore affecting the electrical conductivity. Among the conditions, the surface-polymerized PANI film deposited at room temperature with acetone washing showed the highest conductivity of 22.2 S/cm.

Intrinsic Dawn-Dusk Asymmetry of Magnetotail Thin Current Sheet

NASA Astrophysics Data System (ADS)

Lu, S.; Pritchett, P. L.; Angelopoulos, V.; Artemyev, A.

2017-12-01

Magnetic reconnection and its related phenomena (flux ropes, dipolarization fronts, bursty bulk flows, particle injections, etc.) occur more frequently on the duskside in the Earth's magnetotail. Magnetohydrodynamic simulations attributed the asymmetry to the nonuniform ionospheric conductance through global scale magnetosphere-ionosphere interaction. Hybrid simulations, on the other hand, found an alternative responsible mechanism: the Hall effect in the magnetotail thin current sheet, but left an open question: What is the physical origin of the asymmetric Hall effect? The answer could be the temperature difference on the two sides and/or the dawn-dusk transportation of magnetic flux and plasmas. In this work, we use 3-D particle-in-cell simulations to further explore the magnetotail dawn-dusk asymmetry. The magnetotail equilibrium contains a dipole magnetic field and a current sheet region. The simulation is driven by a symmetric and localized (in the y direction) high-latitude electric field, under which the current sheet thins with a decrease of Bz. During the same time, a dawn-dusk asymmetry is formed intrinsically in the thin current sheet, with a smaller Bz, a stronger Hall effect (indicated by the Hall electric field Ez), and a stronger cross-tail current jy on the duskside. The deep origin of the asymmetry is also shown to be dominated by the dawnward E×B drift of magnetic flux and plasmas. A direct consequence of this intrinsic dawn-dusk asymmetry is that it favors magnetotail reconnection and related phenomena to preferentially occur on the duskside.

One-step electrochemical synthesis of nitrogen and sulfur co-doped, high-quality graphene oxide.

PubMed

Parvez, Khaled; Rincón, Rosalba A; Weber, Nils-Eike; Cha, Kitty C; Venkataraman, Shyam S

2016-04-28

High-quality graphene oxide (GO) with high crystallinity and electrical conductivity as well as in situ doped with nitrogen and sulfur is obtained via the electrochemical exfoliation of graphite. Furthermore, iron incorporated GO sheets show promising catalytic activity and stable methanol tolerance durability when used as electrocatalysts for the oxygen reduction reaction.

Magneto-mechanical modeling of electrical steel sheets

NASA Astrophysics Data System (ADS)

Aydin, U.; Rasilo, P.; Martin, F.; Singh, D.; Daniel, L.; Belahcen, A.; Rekik, M.; Hubert, O.; Kouhia, R.; Arkkio, A.

2017-10-01

A simplified multiscale approach and a Helmholtz free energy based approach for modeling the magneto-mechanical behavior of electrical steel sheets are compared. The models are identified from uniaxial magneto-mechanical measurements of two different electrical steel sheets which show different magneto-elastic behavior. Comparison with the available measurement data of the materials shows that both models successfully model the magneto-mechanical behavior of one of the studied materials, whereas for the second material only the Helmholtz free energy based approach is successful.

Characteristics of Laminating Transparent Conductive Films Aimed at Nursing Indium Ingredient

NASA Astrophysics Data System (ADS)

Ikuta, Kimihiro; Aoki, Takanori; Suzuki, Akio; Matsushita, Tatsuhiko; Okuda, Masahiro

By irradiating ArF excimer laser (λ=193 nm) with energies density 0.8 ∼ 1.4 J/cm2 on the targets of ITO and AZO (Al-doped zinc oxide) by turns, the laminated transparent conducting films composed of ITO (50 nm)/AZO (250 nm) with a total films thickness of 300 nm were fabricated at substrate temperature of 220°C. At laser energy density of 1.2 J/cm2, a sheet resistance of 6.12 Ω/_??_ was obtained under conditions of oxygen pressure of 0.5 Pa for ITO. In addition, electrical characteristics of the laminated transparent conducting composed of ITO/AZO was equal to or more than that of ITO (300 nm). As a result, about 80 percent consumption of ITO was reduced at its maximum. After having examined environmental load, the sheet resistance of the laminated ITO/AZO transparent conductive oxide films did not change and therefore, the durability to the environmental conditions was maintained.

Ag-graphene hybrid conductive ink for writing electronics.

PubMed

Xu, L Y; Yang, G Y; Jing, H Y; Wei, J; Han, Y D

2014-02-07

With the aim of preparing a method for the writing of electronics on paper by the use of common commercial rollerball pens loaded with conductive ink, hybrid conductive ink composed of Ag nanoparticles (15 wt%) and graphene-Ag composite nanosheets (0.15 wt%) formed by depositing Ag nanoparticles (∼10 nm) onto graphene sheets was prepared for the first time. Owing to the electrical pathway effect of graphene and the decreased contact resistance of graphene junctions by depositing Ag nanoparticles (NPs) onto graphene sheets, the concentration of Ag NPs was significantly reduced while maintaining high conductivity at a curing temperature of 100 ° C. A typical resistivity value measured was 1.9 × 10(-7) Ω m, which is 12 times the value for bulk silver. Even over thousands of bending cycles or rolling, the resistance values of writing tracks only increase slightly. The stability and flexibility of the writing circuits are good, demonstrating the promising future of this hybrid ink and direct writing method.

Easily disassembled electrical connector for high voltage, high frequency connections

DOEpatents

Milner, Joseph R.

1994-01-01

An easily accessible electrical connector capable of rapid assembly and disassembly wherein a wide metal conductor sheet may be evenly contacted over the entire width of the conductor sheet by opposing surfaces on the connector which provide an even clamping pressure against opposite surfaces of the metal conductor sheet using a single threaded actuating screw.

Development of fuel cell bipolar plates from graphite filled wet-lay thermoplastic composite materials

NASA Astrophysics Data System (ADS)

Huang, Jianhua; Baird, Donald G.; McGrath, James E.

A method with the potential to produce economical bipolar plates with high electrical conductivity and mechanical properties is described. Thermoplastic composite materials consisting of graphite particles, thermoplastic fibers and glass or carbon fibers are generated by means of a wet-lay (paper-making) process to yield highly formable sheets. The sheets are then stacked and compression molded to form bipolar plates with gas flow channels. Poly(phenylene sulfide) (PPS) based wet-lay composite plates have in-plane conductivity of 200-300 S cm -1, tensile strength of 57 MPa, flexural strength of 96 MPa and impact strength (unnotched) of 81 J m -1 (1.5 ft-lb in. -1). These values well exceed industrial as well as Department of Energy requirements or targets and have never been reached before for composite bipolar plates. The use of wet-lay sheets also makes it possible to choose different components including polymer, graphite particle and reinforcement for the core and outer layers of the plate, respectively, to optimize the properties and/or reduce the cost of the plate. The through-plane conductivity (around 20 S cm -1) and half-cell resistance of the bipolar plate indicate that the through-plane conductivity of the material needs some improvement.

Ambient-Stable and Durable Conductive Ag-Nanowire-Network 2-D Films Decorated with a Ti Layer.

PubMed

Kim, Yoon-Mi; Hwang, Bu-Yeon; Lee, Ki-Wook; Kim, Jin-Yeol

2018-05-11

Highly stable and durable conductive silver nanowire (Ag NW) network electrode films were prepared through decoration with a 5-nm-thick Ti layer. The Ag NW network 2-D films showed sheet resistance values as low as 32 ohm/sq at 88% transparency when decorated with Ti. These 2-D films exhibited a 30% increase in electrical conductivity while maintaining good stability of the films through enhanced resistance to moisture and oxygen penetration as a result of the protective effect of the Ti layer.

On spontaneous formation of current sheets: Untwisted magnetic fields

NASA Astrophysics Data System (ADS)

Bhattacharyya, R.; Low, B. C.; Smolarkiewicz, P. K.

2010-11-01

This is a study of the spontaneous formation of electric current sheets in an incompressible viscous fluid with perfect electrical conductivity, governed by the magnetohydrodynamic Navier-Stokes equations. Numerical solutions to two initial value problems are presented for a three-dimensional, periodic, untwisted magnetic field evolving, with no change in magnetic topology under the frozen-in condition and at characteristic fluid Reynolds numbers of the order of 500, from a nonequilibrium initial state with the fluid at rest. The evolution converts magnetic free energy into kinetic energy to be all dissipated away by viscosity so that the field settles into a minimum-energy, static equilibrium. The solutions demonstrate that, as a consequence of the frozen-in condition, current sheets must form during the evolution despite the geometric simplicity of the prescribed initial fields. In addition to the current sheets associated with magnetic neutral points and field reversal layers, other sheets not associated with such magnetic features are also in evidence. These current sheets form on magnetic flux surfaces. This property is used to achieve a high degree of the frozen-in condition in the simulations, by describing the magnetic field entirely in terms of the advection of its flux surfaces and integrating the resulting governing equations with a customized version of a general-purpose high-resolution (viz., nonoscillatory) hydrodynamical simulation code EULAG [J. M. Prusa et al., Comput. Fluids 37, 1193 (2008)]. Incompressibility imposes the additional global constraint that the flux surfaces must evolve with no change in the spatial volumes they enclose. In this approach, current sheet formation is demonstrated graphically by the progressive pressing together of suitably selected flux surfaces until their separation has diminished below the minimal resolved distance on a fixed grid. The frozen-in condition then fails in the simulation as the field reconnects through an effecting numerical resistivity. The principal results are related to the Parker theory of current-sheet formation and dissipation in the solar corona.

Effect of tail plasma sheet conditions on the penetration of the convection electric field in the inner magnetosphere: RCM simulations with self-consistent magnetic field

NASA Astrophysics Data System (ADS)

Gkioulidou, M.; Wang, C.; Lyons, L. R.; Wolf, R.

2009-12-01

Transport of plasma sheet particles into the inner magnetosphere is strongly affected by the penetration of the convection electric field, which is the result of the large-scale magnetosphere ionosphere electromagnetic coupling. This transport, on the other hand, results in plasma heating and magnetic field stretching, which become very significant in the inner plasma sheet (inside 20 RE). We have previously run simulations with the Rice Convection Model (RCM), using the Tsyganenko 96 magnetic field model, to investigate how the earthward penetration of electric field depends on plasma sheet conditions. Outer proton and electron sources at r ~20 RE, are based on 11 years of Geotail data, and realistically represent the mixture of cold and hot plasma sheet population as a function of MLT and interplanetary conditions. We found that shielding of the inner magnetosphere electric field is more efficient for a colder and denser plasma sheet, which is found following northward IMF, than for the hotter and more tenuous plasma sheet found following southward IMF. Our simulation results so far indicate further earthward penetration of plasma sheet particles in response to enhanced convection if the preceding IMF is southward, which leads to weaker electric field shielding. Recently we have integrated the RCM with a magnetic field solver to obtain magnetic fields that are in force balance with given plasma pressures in the equatorial plane. We expect the self-consistent magnetic field to have a pronounced dawn dusk asymmetry due to the asymmetric inner magnetospheric pressure. This should affect the radial distance and MLT of plasma sheet penetration into the inner magnetosphere. We are currently using this force-balanced and self-consistent model with our realistic boundary conditions to evaluate the dependence of the shielding timescale on pre-existing plasma sheet number density and temperature and to more quantitatively determine the correlation between the plasma sheet conditions and spatial distribution of the penetrating particles. Our results are potentially crucial to understanding the contribution of plasma sheet penetration to the development of the storm-time ring current.

NREL Triples Previous Estimates of U.S. Wind Power Potential (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The National Renewable Energy Laboratory (NREL) recently released new estimates of the U.S. potential for wind-generated electricity, using advanced wind mapping and validation techniques to triple previous estimates of the size of the nation's wind resources. The new study, conducted by NREL and AWS TruePower, finds that the contiguous 48 states have the potential to generate up to 37 million gigawatt-hours annually. In comparison, the total U.S. electricity generation from all sources was roughly 4 million gigawatt-hours in 2009.

Integration of piezo-capacitive and piezo-electric nanoweb based pressure sensors for imaging of static and dynamic pressure distribution.

PubMed

Jeong, Y J; Oh, T I; Woo, E J; Kim, K J

2017-07-01

Recently, highly flexible and soft pressure distribution imaging sensor is in great demand for tactile sensing, gait analysis, ubiquitous life-care based on activity recognition, and therapeutics. In this study, we integrate the piezo-capacitive and piezo-electric nanowebs with the conductive fabric sheets for detecting static and dynamic pressure distributions on a large sensing area. Electrical impedance tomography (EIT) and electric source imaging are applied for reconstructing pressure distribution images from measured current-voltage data on the boundary of the hybrid fabric sensor. We evaluated the piezo-capacitive nanoweb sensor, piezo-electric nanoweb sensor, and hybrid fabric sensor. The results show the feasibility of static and dynamic pressure distribution imaging from the boundary measurements of the fabric sensors.

Apparatus for electrical-assisted incremental forming and process thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roth, John; Cao, Jian

A process and apparatus for forming a sheet metal component using an electric current passing through the component. The process can include providing an incremental forming machine, the machine having at least one arcuate tipped tool and at least electrode spaced a predetermined distance from the arcuate tipped tool. The machine is operable to perform a plurality of incremental deformations on the sheet metal component using the arcuate tipped tool. The machine is also operable to apply an electric direct current through the electrode into the sheet metal component at the predetermined distance from the arcuate tipped tool while themore » machine is forming the sheet metal component.« less

Rational and practical exfoliation of graphite using well-defined poly(3-hexylthiophene) for the preparation of conductive polymer/graphene composite.

PubMed

Iguchi, Hiroki; Higashi, Chisato; Funasaki, Yuichi; Fujita, Keisuke; Mori, Atsunori; Nakasuga, Akira; Maruyama, Tatsuo

2017-01-06

Processing and manipulation of highly conductive pristine graphene in large quantities are still major challenges in the practical application of graphene for electric device. In the present study, we report the liquid-phase exfoliation of graphite in toluene using well-defined poly(3-hexylthiophene) (P3HT) to produce a P3HT/graphene composite. We synthesize and use regioregular P3HT with controlled molecular weights as conductive dispersants for graphene. Simple ultrasonication of graphite flakes with the P3HT successfully produces single-layer and few-layer graphene sheets dispersed in toluene. The produced P3HT/graphene composite can be used as conductive graphene ink, indicating that the P3HT/graphene composite has high electrical conductivity owing to the high conductivity of P3HT and graphene. The P3HT/graphene composite also works as an oxidation-resistant and conductive film for a copper substrate, which is due to the high gas-barrier property of graphene.

Rational and practical exfoliation of graphite using well-defined poly(3-hexylthiophene) for the preparation of conductive polymer/graphene composite

NASA Astrophysics Data System (ADS)

Iguchi, Hiroki; Higashi, Chisato; Funasaki, Yuichi; Fujita, Keisuke; Mori, Atsunori; Nakasuga, Akira; Maruyama, Tatsuo

2017-01-01

Processing and manipulation of highly conductive pristine graphene in large quantities are still major challenges in the practical application of graphene for electric device. In the present study, we report the liquid-phase exfoliation of graphite in toluene using well-defined poly(3-hexylthiophene) (P3HT) to produce a P3HT/graphene composite. We synthesize and use regioregular P3HT with controlled molecular weights as conductive dispersants for graphene. Simple ultrasonication of graphite flakes with the P3HT successfully produces single-layer and few-layer graphene sheets dispersed in toluene. The produced P3HT/graphene composite can be used as conductive graphene ink, indicating that the P3HT/graphene composite has high electrical conductivity owing to the high conductivity of P3HT and graphene. The P3HT/graphene composite also works as an oxidation-resistant and conductive film for a copper substrate, which is due to the high gas-barrier property of graphene.

Rational and practical exfoliation of graphite using well-defined poly(3-hexylthiophene) for the preparation of conductive polymer/graphene composite

PubMed Central

Iguchi, Hiroki; Higashi, Chisato; Funasaki, Yuichi; Fujita, Keisuke; Mori, Atsunori; Nakasuga, Akira; Maruyama, Tatsuo

2017-01-01

Processing and manipulation of highly conductive pristine graphene in large quantities are still major challenges in the practical application of graphene for electric device. In the present study, we report the liquid-phase exfoliation of graphite in toluene using well-defined poly(3-hexylthiophene) (P3HT) to produce a P3HT/graphene composite. We synthesize and use regioregular P3HT with controlled molecular weights as conductive dispersants for graphene. Simple ultrasonication of graphite flakes with the P3HT successfully produces single-layer and few-layer graphene sheets dispersed in toluene. The produced P3HT/graphene composite can be used as conductive graphene ink, indicating that the P3HT/graphene composite has high electrical conductivity owing to the high conductivity of P3HT and graphene. The P3HT/graphene composite also works as an oxidation-resistant and conductive film for a copper substrate, which is due to the high gas-barrier property of graphene. PMID:28059127

AC Electric Field Activated Shape Memory Polymer Composite

NASA Technical Reports Server (NTRS)

Kang, Jin Ho; Siochi, Emilie J.; Penner, Ronald K.; Turner, Travis L.

2011-01-01

Shape memory materials have drawn interest for applications like intelligent medical devices, deployable space structures and morphing structures. Compared to other shape memory materials like shape memory alloys (SMAs) or shape memory ceramics (SMCs), shape memory polymers (SMPs) have high elastic deformation that is amenable to tailored of mechanical properties, have lower density, and are easily processed. However, SMPs have low recovery stress and long response times. A new shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive fillers to enhance its thermo-mechanical characteristics. A new composition of shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive functionalized graphene sheets (FGS) to enhance its thermo-mechanical characteristics. The elastic modulus of LaRC-SMPC is approximately 2.7 GPa at room temperature and 4.3 MPa above its glass transition temperature. Conductive FGSs-doped LaRC-SMPC exhibited higher conductivity compared to pristine LaRC SMP. Applying an electric field at between 0.1 Hz and 1 kHz induced faster heating to activate the LaRC-SMPC s shape memory effect relative to applying DC electric field or AC electric field at frequencies exceeding1 kHz.

Polymer/Pristine graphene based composites: from emulsions to strong, electrically conducting foams

DOE PAGES

Woltornist, Steven J.; Carrillo, Jan-Michael Y.; Xu, Thomas O.; ...

2015-01-21

The unique electrical, thermal, and mechanical properties of graphene make it a perfect candidate for applications in graphene/graphite based polymer composites, yet challenges due to the lack of solubility of pristine graphene/graphite in water and common organic solvents have limited its practical utilization. In this paper, we report a scalable and environmentally friendly technique to form water-in-oil type emulsions stabilized by overlapping pristine graphene sheets, enabling the synthesis of open cell foams containing a continuous graphitic network. Our approach utilizes the insolubility of graphene/graphite in both water and organic solvents and so does not require oxidation, reduction, surfactants, high boilingmore » solvents, chemical functionalization, or the input of large amounts of mechanical energy or heat. At the heart of our technique is the strong attraction of graphene to high-energy oil and water interfaces. This allows for the creation of stable water-in-oil emulsions with controlled droplet size and overlapping graphene sheets playing the role of surfactant by covering the droplet surface and stabilizing the interfaces with a thin graphitic skin. Finally, these emulsions are used as templates for the synthesis of open cell foams with densities below 0.35 g/cm 3 that exhibit remarkable mechanical and electrical properties including compressive moduli up to ~100 MPa, compressive strengths of over 8.3 MPa (1200 psi), and bulk conductivities approaching 7 S/m.« less

Poker flat radar observations of the magnetosphere-ionosphere coupling electrodynamics of the earthward penetrating plasma sheet following convection enhancements

NASA Astrophysics Data System (ADS)

Lyons, L. R.; Zou, S.; Heinselman, C. J.; Nicolls, M. J.; Anderson, P. C.

2009-05-01

The plasma sheet moves earthward (equatorward in the ionosphere) after enhancements in convection, and the electrodynamics of this response is strongly influenced by Region 2 magnetosphere-ionosphere coupling. We have used Poker Flat Advanced Modular Incoherent Scatter Radar (PFISR) observations associated with two relatively abrupt southward turnings of the IMF to provide an initial evaluation of aspects of this response. The observations show that strong westward sub-auroral polarization streams (SAPS) flow regions moved equatorward as the plasma sheet electron precipitation (the diffuse aurora) penetrated equatorward following the IMF southward turnings. Consistent with our identification of these flows as SAPS, concurrent DMSP particle precipitation measurements show the equatorial boundary of ion precipitation equatorward of the electron precipitation boundary and that westward flows lie within the low-conductivity region between the two boundaries where the plasma sheet ion pressure gradient is expected to drive downward R2 currents. Evidence for these downward currents is seen in the DMSP magnetometer observations. Preliminary examination indicates that the SAPS response seen in the examples presented here may be common. However, detailed analysis will be required for many more events to reliably determine if this is the case. If so, it would imply that SAPS are frequently an important aspect of the inner magnetospheric electric field distribution, and that they are critical for understanding the response of the magnetosphere-ionosphere system to enhancements in convection, including understanding the earthward penetration of the plasma sheet. This earthward penetration is critical to geomagnetic disturbance phenomena such as the substorm growth phase and the formation of the stormtime ring current. Additionally, for one example, a prompt electric field response to the IMF southward turnings is seen within the inner plasma sheet.

Rapid Characterization of Bacterial Electrogenicity Using a Single-Sheet Paper-Based Electrofluidic Array

PubMed Central

Gao, Yang; Hassett, Daniel J.; Choi, Seokheun

2017-01-01

Electrogenicity, or bacterial electron transfer capacity, is an important application which offers environmentally sustainable advances in the fields of biofuels, wastewater treatment, bioremediation, desalination, and biosensing. Significant boosts in this technology can be achieved with the growth of synthetic biology that manipulates microbial electron transfer pathways, thereby potentially significantly improving their electrogenic potential. There is currently a need for a high-throughput, rapid, and highly sensitive test array to evaluate the electrogenic properties of newly discovered and/or genetically engineered bacterial species. In this work, we report a single-sheet, paper-based electrofluidic (incorporating both electronic and fluidic structure) screening platform for rapid, sensitive, and potentially high-throughput characterization of bacterial electrogenicity. This novel screening array uses (i) a commercially available wax printer for hydrophobic wax patterning on a single sheet of paper and (ii) water-dispersed electrically conducting polymer mixture, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, for full integration of electronic and fluidic components into the paper substrate. The engineered 3-D, microporous, hydrophilic, and conductive paper structure provides a large surface area for efficient electron transfer. This results in rapid and sensitive power assessment of electrogenic bacteria from a microliter sample volume. We validated the effectiveness of the sensor array using hypothesis-driven genetically modified Pseudomonas aeruginosa mutant strains. Within 20 min, we observed that the sensor platform successfully measured the electricity-generating capacities of five isogenic mutants of P. aeruginosa while distinguishing their differences from genetically unmodified bacteria. PMID:28798914

Easily disassembled electrical connector for high voltage, high frequency connections

DOEpatents

Milner, J.R.

1994-05-10

An easily accessible electrical connector capable of rapid assembly and disassembly is described wherein a wide metal conductor sheet may be evenly contacted over the entire width of the conductor sheet by opposing surfaces on the connector which provide an even clamping pressure against opposite surfaces of the metal conductor sheet using a single threaded actuating screw. 13 figures.

Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

NASA Astrophysics Data System (ADS)

Maeda, Yoshitaka; Urata, Shinya; Nakai, Hideo; Takeuchi, Yuuya; Yun, Kyyoul; Yanase, Shunji; Okazaki, Yasuo

2017-05-01

In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D) magnetic properties (properties under the arbitrary alternating and the rotating flux conditions) of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

Electric field induced sheeting and breakup of dielectric liquid jets

NASA Astrophysics Data System (ADS)

Khoshnevis, Ahmad; Tsai, Scott S. H.; Esmaeilzadeh, Esmaeil

2014-01-01

We report experimental observations of the controlled deformation of a dielectric liquid jet subjected to a local high-voltage electrostatic field in the direction normal to the jet. The jet deforms to the shape of an elliptic cylinder upon application of a normal electrostatic field. As the applied electric field strength is increased, the elliptic cylindrical jet deforms permanently into a flat sheet, and eventually breaks-up into droplets. We interpret this observation—the stretch of the jet is in the normal direction to the applied electric field—qualitatively using the Taylor-Melcher leaky dielectric theory, and develop a simple scaling model that predicts the critical electric field strength for the jet-to-sheet transition. Our model shows a good agreement with experimental results, and has a form that is consistent with the classical drop deformation criterion in the Taylor-Melcher theory. Finally, we statistically analyze the resultant droplets from sheet breakup, and find that increasing the applied electric field strength improves droplet uniformity and reduces droplet size.

Carbon Nanotube Thin-Film Antennas.

PubMed

Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

2016-08-17

Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of <10 ohm/sq is needed to achieve a 10 dB return loss in the unbalanced antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

Localization and hopping conduction in glass and crystal phases of monatomic Au layers on a silicon surface

NASA Astrophysics Data System (ADS)

Yamazaki, Shiro; Matsuda, Iwao; Okino, Hiroyuki; Morikawa, Harumo; Hasegawa, Shuji

2009-02-01

Monatomic layers of Au on Si(111) exhibit a glass-crystal phase transition between the ordered crystalline 6×6 reconstruction and the disordered glassy β-3×3 reconstruction on thermal annealing. Micro-four-point-probe electrical conductivity measurements clearly revealed that both monatomic layers had conductivities as large as the minimum metallic conductivity at the low-temperature region (˜10-100K) , and were well described by transport theory regarding Anderson localization. The sheet conductivity of the 6×6 was higher than that of the β-3×3 , which was attributed to different degrees of carrier localization.

An electrically resistive sheet of glial cells for amplifying signals of neuronal extracellular recordings

PubMed Central

Matsumura, R.; Yamamoto, H.; Niwano, M.; Hirano-Iwata, A.

2016-01-01

Electrical signals of neuronal cells can be recorded non-invasively and with a high degree of temporal resolution using multielectrode arrays (MEAs). However, signals that are recorded with these devices are small, usually 0.01%–0.1% of intracellular recordings. Here, we show that the amplitude of neuronal signals recorded with MEA devices can be amplified by covering neuronal networks with an electrically resistive sheet. The resistive sheet used in this study is a monolayer of glial cells, supportive cells in the brain. The glial cells were grown on a collagen-gel film that is permeable to oxygen and other nutrients. The impedance of the glial sheet was measured by electrochemical impedance spectroscopy, and equivalent circuit simulations were performed to theoretically investigate the effect of covering the neurons with such a resistive sheet. Finally, the effect of the resistive glial sheet was confirmed experimentally, showing a 6-fold increase in neuronal signals. This technique feasibly amplifies signals of MEA recordings. PMID:27703279

Transparent, Weakly Conductive Films for Space Applications

NASA Technical Reports Server (NTRS)

Griffin, John; Morgan, Ashraf; Hambourger, Paul D.

2004-01-01

Electrically insulating spacecraft surfaces are vulnerable to nonuniform charge buildup due to particles emitted by the sun. On Mars, insulating surfaces of exploration vehicles and structures will be affected by dust coatings possibly held in place by triboelectric surface charge. Application of a conductive film may be a solution to the charging problem, but the coating must be highly transparent if used on solar panels, lenses, etc. Sheet resistivity requirements depend on the application and are in the range 10(exp 2) - 10(exp 8) ohms/square. Co-deposited indium tin oxide (ITO) and MgF2 is promising, with high transparency, tailorable electrical properties, and durability to atomic oxygen. Due to ITO's relatively narrow bandgap (approximately 3.5 eV), the film might absorb enough ultraviolet to protect polymeric substrates. Recent work on dual-magnetron-sputtered ITO-MgF2 showed that a variety of polymeric substrates can be coated at room temperature. However, the sheet resistivity is very sensitive to composition, suggestive of a percolation transition. This could be a serious problem for large-scale coating production. We will report on attempts to control film composition by plasma emission monitoring of the ITO and MgF2 guns.

Method and apparatus for capacitive deionization, electrochemical purification, and regeneration of electrodes

DOEpatents

Farmer, Joseph

1995-01-01

An electrochemical cell for capacitive deionization and electrochemical purification and regeneration of electrodes includes two oppositely disposed, spaced-apart end plates, one at each end of the cell. Two generally identical single-sided end electrodes, are arranged one at each end of the cell, adjacent to the end plates. An insulator layer is interposed between each end plate and the adjacent end electrode. Each end electrode includes a single sheet of conductive material having a high specific surface area and sorption capacity. In the preferred embodiment, the sheet of conductive material is formed of carbon aerogel composite. The cell further includes a plurality of generally identical double-sided intermediate electrodes that are equidistally separated from each other, between the two end electrodes. As the electrolyte enters the cell, it flows through a continuous open serpentine channel defined by the electrodes, substantially parallel to the surfaces of the electrodes. By polarizing the cell, ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the cell is saturated with the removed ions, the cell is regenerated electrically, thus significantly minimizing secondary wastes.

Method and apparatus for capacitive deionization, electrochemical purification, and regeneration of electrodes

DOEpatents

Farmer, J.

1995-06-20

An electrochemical cell for capacitive deionization and electrochemical purification and regeneration of electrodes includes two oppositely disposed, spaced-apart end plates, one at each end of the cell. Two generally identical single-sided end electrodes, are arranged one at each end of the cell, adjacent to the end plates. An insulator layer is interposed between each end plate and the adjacent end electrode. Each end electrode includes a single sheet of conductive material having a high specific surface area and sorption capacity. In the preferred embodiment, the sheet of conductive material is formed of carbon aerogel composite. The cell further includes a plurality of generally identical double-sided intermediate electrodes that are equidistantly separated from each other, between the two end electrodes. As the electrolyte enters the cell, it flows through a continuous open serpentine channel defined by the electrodes, substantially parallel to the surfaces of the electrodes. By polarizing the cell, ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the cell is saturated with the removed ions, the cell is regenerated electrically, thus significantly minimizing secondary wastes. 17 figs.

A kirigami approach to engineering elasticity in nanocomposites through patterned defects.

PubMed

Shyu, Terry C; Damasceno, Pablo F; Dodd, Paul M; Lamoureux, Aaron; Xu, Lizhi; Shlian, Matthew; Shtein, Max; Glotzer, Sharon C; Kotov, Nicholas A

2015-08-01

Efforts to impart elasticity and multifunctionality in nanocomposites focus mainly on integrating polymeric and nanoscale components. Yet owing to the stochastic emergence and distribution of strain-concentrating defects and to the stiffening of nanoscale components at high strains, such composites often possess unpredictable strain-property relationships. Here, by taking inspiration from kirigami—the Japanese art of paper cutting—we show that a network of notches made in rigid nanocomposite and other composite sheets by top-down patterning techniques prevents unpredictable local failure and increases the ultimate strain of the sheets from 4 to 370%. We also show that the sheets' tensile behaviour can be accurately predicted through finite-element modelling. Moreover, in marked contrast to other stretchable conductors, the electrical conductance of the stretchable kirigami sheets is maintained over the entire strain regime, and we demonstrate their use to tune plasma-discharge phenomena. The unique properties of kirigami nanocomposites as plasma electrodes open up a wide range of novel technological solutions for stretchable electronics and optoelectronic devices, among other application possibilities.

Polymer thick-film conductors and dielectrics for membrane switches and flexible circuitry

NASA Technical Reports Server (NTRS)

Nazarenko, N.

1983-01-01

The fabrication and operation of membrane switches are discussed. The membrane switch functions as a normally open, momentary contact, low-voltage pressure-sensitive device. Its design is a three-layer sandwich usually constructed of polyester film. Conductive patterns are deposited onto the inner side of top and bottom sheets by silk screening. The center spacer is then placed between the two circuit layers to form a sandwich, generally held together by an adhesive. When pressure is applied to the top layer, it flexes through the punched openings of the spacer to establish electrical contact between conductive pads of the upper and lower sheets, momentarily closing the circuit. Upon release of force the top sheet springs back to its normal open position. The membrane touch switch is being used in a rapidly expanding range of applications, including instrumentation, appliances, electronic games and keyboards. Its board acceptance results from its low cost, durability, ease of manufacture, cosmetic appeal and design flexibility. The principal electronic components in the membrane switch are the conductor and dielectric.

Optimization of chemical structure of Schottky-type selection diode for crossbar resistive memory.

PubMed

Kim, Gun Hwan; Lee, Jong Ho; Jeon, Woojin; Song, Seul Ji; Seok, Jun Yeong; Yoon, Jung Ho; Yoon, Kyung Jean; Park, Tae Joo; Hwang, Cheol Seong

2012-10-24

The electrical performances of Pt/TiO(2)/Ti/Pt stacked Schottky-type diode (SD) was systematically examined, and this performance is dependent on the chemical structures of the each layer and their interfaces. The Ti layers containing a tolerable amount of oxygen showed metallic electrical conduction characteristics, which was confirmed by sheet resistance measurement with elevating the temperature, transmission line measurement (TLM), and Auger electron spectroscopy (AES) analysis. However, the chemical structure of SD stack and resulting electrical properties were crucially affected by the dissolved oxygen concentration in the Ti layers. The lower oxidation potential of the Ti layer with initially higher oxygen concentration suppressed the oxygen deficiency of the overlying TiO(2) layer induced by consumption of the oxygen from TiO(2) layer. This structure results in the lower reverse current of SDs without significant degradation of forward-state current. Conductive atomic force microscopy (CAFM) analysis showed the current conduction through the local conduction paths in the presented SDs, which guarantees a sufficient forward-current density as a selection device for highly integrated crossbar array resistive memory.

A numerical study of magnetohydrodynamic transport of nanofluids over a vertical stretching sheet with exponential temperature-dependent viscosity and buoyancy effects

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher; Tripathi, Dharmendra; Khan, Zafar Hayat; Bég, O. Anwar

2016-09-01

In this paper, a mathematical study is conducted of steady incompressible flow of a temperature-dependent viscous nanofluid from a vertical stretching sheet under applied external magnetic field and gravitational body force effects. The Reynolds exponential viscosity model is deployed. Electrically-conducting nanofluids are considered which comprise a suspension of uniform dimension nanoparticles suspended in viscous base fluid. The nanofluid sheet is extended with a linear velocity in the axial direction. The Buonjiornio model is utilized which features Brownian motion and thermophoresis effects. The partial differential equations for mass, momentum, energy and species (nano-particle concentration) are formulated with magnetic body force term. Viscous and Joule dissipation effects are neglected. The emerging nonlinear, coupled, boundary value problem is solved numerically using the Runge-Kutta fourth order method along with a shooting technique. Graphical solutions for velocity, temperature, concentration field, skin friction and Nusselt number are presented. Furthermore stream function plots are also included. Validation with Nakamura's finite difference algorithm is included. Increasing nanofluid viscosity is observed to enhance temperatures and concentrations but to reduce velocity magnitudes. Nusselt number is enhanced with both thermal and species Grashof numbers whereas it is reduced with increasing thermophoresis parameter and Schmidt number. The model is applicable in nano-material manufacturing processes involving extruding sheets.

48. OUTLET WORKS: ELECTRICAL SYSTEM NO. 3. Sheet H3, October, ...

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

48. OUTLET WORKS: ELECTRICAL SYSTEM NO. 3. Sheet H-3, October, 1939. File no. SA 342/59. - Prado Dam, Outlet Works, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

Electric fields in the plasma sheet and plasma sheet boundary layer

NASA Technical Reports Server (NTRS)

Pedersen, A.; Knott, K.; Cattell, C. A.; Mozer, F. S.; Falthammar, C.-G.; Lindqvist, P.-A.; Manka, R. H.

1985-01-01

Results obtained by Forbes et al. (1981) on the basis of time delay measurements between ISEE 1 and ISEE 2 imply that the plasma flow and the boundary contracting velocity were nearly the same, whereas the expanding boundary velocity was not accompanied by any significant plasma sheet plasma motion. In the present study, this observation is discussed in conjunction with electric field data. The study is based on electric field data from the spherical double probe experiment on ISEE 1. Electric field data from GEOS 2 are used to some extent to monitor the electric fields near the geostationary orbit during the considered eve nts. Electric field data during CDAW 6 events are discussed, taking into account positions of ISEE 1/ISEE 2 and GEOS 2; March 22, 0600-1300 UT; and March 22, UT; and March 31, 1400-2400 UT.

Carbon Nanotube Networks Reinforced by Silver Nanowires with Improved Optical Transparency and Conductivity

NASA Astrophysics Data System (ADS)

Martine, Patricia; Fakhimi, Azin; Lin, Ling; Jurewicz, Izabela; Dalton, Alan; Zakhidov, Anvar A.; Baughman, Ray H.

2015-03-01

We have fabricated highly transparent and conductive free-standing nanocomposite thin film electrodes by adding silver nanowires (AgNWs) to dry-spun Multiwall Carbon Nanotube (MWNT) aerogels. This nanocomposite exhibits desirable properties such as high optical transmittance, excellent flexibility and enhanced electrical conductivity. The incorporation of the AgNWs to the MWNT aerogels was accomplished by using a spray coating method. The optical transparency and sheet resistance of the nanocomposite was tuned by adjusting the concentration of AgNWs, back pressure and nozzle distance of the spray gun to the MWNT aerogel during deposition. As the solvent evaporated, the aerogel MWNT bundles densified via surface tension which caused the MWNT bundles to collapse. This adjustable process was responsible in forming well defined apertures that increased the nanocomposite's transmittance up to 90 percent. Via AgNWs percolation and random interconnections between separate MWNT bundles in the aerogel matrix, the sheet resistance decreased from 1 K ohm/sq to less than 100 ohm/sq. Alan G. MacDiarmid NanoTech Institute

47. OUTLET WORKS: ELECTRICAL SYSTEM NO. 2. Sheet H2, date ...

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

47. OUTLET WORKS: ELECTRICAL SYSTEM NO. 2. Sheet H-2, date stamped May, 1939. File no. SA 342/10. - Prado Dam, Outlet Works, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

46. OUTLET WORKS: ELECTRICAL SYSTEM NO. 1. Sheet H1, date ...

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

46. OUTLET WORKS: ELECTRICAL SYSTEM NO. 1. Sheet H-1, date stamped May, 1939. File no. SA 342/9. - Prado Dam, Outlet Works, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

75 FR 5146 - Tempel Steel Company Including On-Site Leased Workers From Aerotek Staffing Chicago, IL; Tempel...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-01

... the production of lamination sheet steel for electric motors and transformers. New findings show that... affected by a shift in production of lamination sheet steel for electric motors and transformers to Mexico...

Electrode material comprising graphene-composite materials in a graphite network

DOEpatents

Kung, Harold H.; Lee, Jung K.

2014-07-15

A durable electrode material suitable for use in Li ion batteries is provided. The material is comprised of a continuous network of graphite regions integrated with, and in good electrical contact with a composite comprising graphene sheets and an electrically active material, such as silicon, wherein the electrically active material is dispersed between, and supported by, the graphene sheets.

Related Instructional Material for Electrical Apprentice Technical Training. Student Worksheets. Series C (Third Year). Revised to Meet 1978 Electrical Code.

ERIC Educational Resources Information Center

North Carolina State Dept. of Community Colleges, Raleigh.

Information sheets and student worksheets for twenty-five lesson plans designed for a third-year electrical apprentice technical training program are presented in this workbook. The information sheets provide summary information about the lesson topics and the worksheets contain problems to be solved and questions to be answered relating to each…

Related Instructional Material for Electrical Apprentice Technical Training. Student Worksheets. Series D (Fourth Year). Revised to Meet 1978 Electrical Code.

ERIC Educational Resources Information Center

North Carolina State Dept. of Community Colleges, Raleigh.

Information sheets and student worksheets for twenty-seven lesson plans designed for a fourth-year electrical apprentice technical training program are presented in this workbook. The information sheets provide summary information about the lesson topics and the worksheets contain problems to be solved and questions to be answered relating to each…

Electrode material comprising graphene-composite materials in a graphite network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kung, Harold H.; Lee, Jung K.

A durable electrode material suitable for use in Li ion batteries is provided. The material is comprised of a continuous network of graphite regions integrated with, and in good electrical contact with a composite comprising graphene sheets and an electrically active material, such as silicon, wherein the electrically active material is dispersed between, and supported by, the graphene sheets.

Fabrication of highly conductive graphene/ITO transparent bi-film through CVD and organic additives-free sol-gel techniques.

PubMed

Hemasiri, Bastian Waduge Naveen Harindu; Kim, Jae-Kwan; Lee, Ji-Myon

2017-12-19

Indium tin oxide (ITO) still remains as the main candidate for high-performance optoelectronic devices, but there is a vital requirement in the development of sol-gel based synthesizing techniques with regards to green environment and higher conductivity. Graphene/ITO transparent bi-film was synthesized by a two-step process: 10 wt. % tin-doped ITO thin films were produced by an environmentally friendly aqueous sol-gel spin coating technique with economical salts of In(NO 3 ) 3 .H 2 O and SnCl 4 , without using organic additives, on surface free energy enhanced (from 53.826 to 97.698 mJm -2 ) glass substrate by oxygen plasma treatment, which facilitated void-free continuous ITO film due to high surface wetting. The chemical vapor deposited monolayer graphene was transferred onto the synthesized ITO to enhance its electrical properties and it was capable of reducing sheet resistance over 12% while preserving the bi-film surface smoother. The ITO films contain the In 2 O 3 phase only and exhibit the polycrystalline nature of cubic structure with 14.35 ± 0.5 nm crystallite size. The graphene/ITO bi-film exhibits reproducible optical transparency with 88.66% transmittance at 550 nm wavelength, and electrical conductivity with sheet resistance of 117 Ω/sq which is much lower than that of individual sol-gel derived ITO film.

Flexible and reversibly deformable radio-frequency antenna based on stretchable SWCNTs/PANI/Lycra conductive fabric

NASA Astrophysics Data System (ADS)

Guo, Xiaohui; Huang, Ying; Wu, Can; Mao, Leidong; Wang, Yue; Xie, Zhicheng; Liu, Caixia; Zhang, Yugang

2017-10-01

We demonstrated a flexible and reversibly deformable radio-frequency antenna based on SWCNTs/PANI/Lycra conductive fabric and semipermeable film for wireless wearable communications applications. The conductive fabric fabricated by using the ‘dip and dry’ process exhibits good flexibility, electrical stability, stretchability and mechanical properties, and a high electrical conductivity (with low sheet resistance of ˜35 Ω/sq) was obtained based on the SWCNTs/PANI synergistic conductive network. The morphology of the semipermeable film was investigated to further illustrate the waterproof breathable features. Meanwhile, the modeling, fabrication procedure and radiating properties of the radio-frequency textile antenna worked at 2.45 GHz were systematically illustrated. The measured reflection coefficient, VSWR and the -10 dB bandwidth is ˜-18.6 dB, 1.58 and ˜270 MHz respectively, which agreed well with the simulation results. Furthermore, the results indicate that the design methodology for the radio-frequency textile antenna could have promising applications in flexible and reversibly deformable antennas for wearable wireless communications systems.

Hand-Drawn Resistors and a Simple Tester Using a Light-Emitting Diode

ERIC Educational Resources Information Center

Kamata, Masahiro; Abe, Mayumi

2012-01-01

A thick line drawn on a sheet of paper with a 6B pencil is electrically conductive and its resistance can be roughly estimated using a simple tester made of a light-emitting diode (LED) and a lithium coin-type cell. Using this hand-drawn resistor and the LED tester, we developed teaching materials that help students to understand how electrical…

Nanoscale current spreading analysis in solution-processed graphene oxide/silver nanowire transparent electrodes via conductive atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, Joseph E.; Perumal, Ajay; Bradley, Donal D. C.

2016-05-21

We use conductive atomic force microscopy (CAFM) to study the origin of long-range conductivity in model transparent conductive electrodes composed of networks of reduced graphene oxide (rGO{sub X}) and silver nanowires (AgNWs), with nanoscale spatial resolution. Pristine networks of rGO{sub X} (1–3 monolayers-thick) and AgNWs exhibit sheet resistances of ∼100–1000 kΩ/□ and 100–900 Ω/□, respectively. When the materials are deposited sequentially to form bilayer rGO{sub X}/AgNW electrodes and thermally annealed at 200 °C, the sheet resistance reduces by up to 36% as compared to pristine AgNW networks. CAFM was used to analyze the current spreading in both systems in order to identify themore » nanoscale phenomena responsible for this effect. For rGO{sub X} networks, the low intra-flake conductivity and the inter-flake contact resistance is found to dominate the macroscopic sheet resistance, while for AgNW networks the latter is determined by the density of the inter-AgNW junctions and their associated resistance. In the case of the bilayer rGO{sub X}/AgNWs' networks, rGO{sub X} flakes are found to form conductive “bridges” between AgNWs. We show that these additional nanoscopic electrical connections are responsible for the enhanced macroscopic conductivity of the bilayer rGO{sub X}/AgNW electrodes. Finally, the critical role of thermal annealing on the formation of these nanoscopic connections is discussed.« less

Contactless Mobility, Carrier Density, and Sheet Resistance Measurements on Si, GaN, and AlGaN/GaN High Electron Mobility Transistor (HEMT) Wafers

DTIC Science & Technology

2015-02-01

to the electrical characterization of semiconductor materials. The Hall effect occurs when an electrical conductor is placed in a magnetic field...system. The TE11 mode is caused by the Hall effect when under an applied magnetic field. This effect rotates the TE10 mode 90° where the forward...conductivity tensors σxx and σxy, where σxx and σxy are functions of the magnetic field (H). The Hall coefficient (RH) for a given H is then

Electrical conductivity of In₂O₃ and Ga₂O₃ after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level.

PubMed

Vines, Lasse; Bhoodoo, Chidanand; von Wenckstern, Holger; Grundmann, Marius

2017-11-29

The evolution of sheet resistance of n-type In2O3 and Ga2O3 exposed to bombardment with MeV 12C and 28Si ions at 35 K is studied in situ. While the sheet resistance of Ga2O3 increased by more than 8 orders of magnitude as a result of ion irradiation, In2O3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga2O3 remained highly resistive, while In2O3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to 2 1012 cm2. A model where larger defect complexes preferentially produce donor like defects in In2O3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed. © 2017 IOP Publishing Ltd.

Thermal energy creation and transport and X-ray/EUV emission in a thermodynamic MHD CME simulation

NASA Astrophysics Data System (ADS)

Reeves, K.; Mikic, Z.; Torok, T.; Linker, J.; Murphy, N. A.

2017-12-01

We model a CME using the PSI 3D numerical MHD code that includes coronal heating, thermal conduction and radiative cooling in the energy equation. The magnetic flux distribution at 1 Rs is produced by a localized subsurface dipole superimposed on a global dipole field, mimicking the presence of an active region within the global corona. We introduce transverse electric fields near the neutral line in the active region to form a flux rope, then a converging flow is imposed that causes the eruption. We follow the formation and evolution of the current sheet and find that instabilities set in soon after the reconnection commences. We simulate XRT and AIA EUV emission and find that the instabilities manifest as bright features emanating from the reconnection region. We examine the quantities responsible for plasma heating and cooling during the eruption, including thermal conduction, radiation, adiabatic compression and expansion, coronal heating and ohmic heating due to dissipation of currents. We find that the adiabatic compression plays an important role in heating the plasma around the current sheet, especially in the later stages of the eruption when the instabilities are present. Thermal conduction also plays an important role in the transport of thermal energy away from the current sheet region throughout the reconnection process.

Fact Sheet: 2015 Final Rule on the Disposal of Coal Combustion Residuals Generated by Electric Utilities

EPA Pesticide Factsheets

This fact sheet describes the final rule signed on December 19, 2014 establishing a comprehensive set of requirements for the disposal of coal combustion residuals generated by electric utilities in landfills and surface impoundments.

Electric fields measured by ISEE-1 within and near the neutral sheet during quiet and active times

NASA Technical Reports Server (NTRS)

Cattell, C. A.; Mozer, F. S.

1982-01-01

An understanding of the physical processes occurring in the magnetotail and plasmasheet during different interplanetary magnetic field orientations and differing levels of ground magnetic activity is crucial for the development of a theory of energy transfer from the solar wind to the particles which produce auroral arcs. In the present investigation, the first observations of electric fields during neutral sheet crossings are presented, taking into account the statistical correlations of the interplanetary magnetic field direction and ground activity with the character of the electric field. The electric field data used in the study were obtained from a double probe experiment on the ISEE-1 satellite. The observations suggest that turbulent electric and magnetic fields are intimately related to plasma acceleration in the neutral sheet and to the processes which create auroral particles.

MHD stagnation point flow and heat transfer of a nanofluid over a permeable nonlinear stretching/shrinking sheet with viscous dissipation effect

NASA Astrophysics Data System (ADS)

Jusoh, Rahimah; Nazar, Roslinda

2018-04-01

The magnetohydrodynamic (MHD) stagnation point flow and heat transfer of an electrically conducting nanofluid over a nonlinear stretching/shrinking sheet is studied numerically. Mathematical modelling and analysis are attended in the presence of viscous dissipation. Appropriate similarity transformations are used to reduce the boundary layer equations for momentum, energy and concentration into a set of ordinary differential equations. The reduced equations are solved numerically using the built in bvp4c function in Matlab. The numerical and graphical results on the effects of various parameters on the velocity and temperature profiles as well as the skin friction coefficient and the local Nusselt number are analyzed and discussed in this paper. The study discovers the existence of dual solutions for a certain range of the suction parameter. The conducted stability analysis reveals that the first solution is stable and feasible, while the second solution is unstable.

Nano-scaled graphene platelets with a high length-to-width aspect ratio

DOEpatents

Zhamu, Aruna; Guo, Jiusheng; Jang, Bor Z.

2010-09-07

This invention provides a nano-scaled graphene platelet (NGP) having a thickness no greater than 100 nm and a length-to-width ratio no less than 3 (preferably greater than 10). The NGP with a high length-to-width ratio can be prepared by using a method comprising (a) intercalating a carbon fiber or graphite fiber with an intercalate to form an intercalated fiber; (b) exfoliating the intercalated fiber to obtain an exfoliated fiber comprising graphene sheets or flakes; and (c) separating the graphene sheets or flakes to obtain nano-scaled graphene platelets. The invention also provides a nanocomposite material comprising an NGP with a high length-to-width ratio. Such a nanocomposite can become electrically conductive with a small weight fraction of NGPs. Conductive composites are particularly useful for shielding of sensitive electronic equipment against electromagnetic interference (EMI) or radio frequency interference (RFI), and for electrostatic charge dissipation.

Fabrication and stability investigation of ultra-thin transparent and flexible Cu-Ag-Au tri-layer film on PET

NASA Astrophysics Data System (ADS)

Prakasarao, Ch Surya; D'souza, Slavia Deeksha; Hazarika, Pratim; Karthiselva N., S.; Ramesh Babu, R.; Kovendhan, M.; Kumar, R. Arockia; Joseph, D. Paul

2018-04-01

The need for transparent conducting electrodes with high transmittance, low sheet resistance and flexibility to replace Indium Tin Oxide is ever growing. We have deposited and studied the performance of ultra-thin Cu-Ag-Au tri-layer films over a flexible poly-ethylene terephthalate substrate. Scotch tape test showed good adhesion of the metallic film. Transmittance of the tri-layer was around 40 % in visible region. Optical profiler measurements were done to study the surface features. The XRD pattern revealed that film was amorphous. Sheet resistance measured by four probe technique was around 7.7 Ohm/Δ and was stable up to 423 K. The transport parameters by Hall effect showed high conductivity and carrier concentration with a mobility of 5.58 cm2/Vs. Tests performed in an indigenously designed bending unit indicated the films to be stable both mechanically and electrically even after 50,000 bending cycles.

On MHD nonlinear stretching flow of Powell-Eyring nanomaterial

NASA Astrophysics Data System (ADS)

Hayat, Tasawar; Sajjad, Rai; Muhammad, Taseer; Alsaedi, Ahmed; Ellahi, Rahmat

This communication addresses the magnetohydrodynamic (MHD) flow of Powell-Eyring nanomaterial bounded by a nonlinear stretching sheet. Novel features regarding thermophoresis and Brownian motion are taken into consideration. Powell-Eyring fluid is electrically conducted subject to non-uniform applied magnetic field. Assumptions of small magnetic Reynolds number and boundary layer approximation are employed in the mathematical development. Zero nanoparticles mass flux condition at the sheet is selected. Adequate transformation yield nonlinear ordinary differential systems. The developed nonlinear systems have been computed through the homotopic approach. Effects of different pertinent parameters on velocity, temperature and concentration fields are studied and analyzed. Further numerical data of skin friction and heat transfer rate is also tabulated and interpreted.

Silylated functionalized silicon-based composite as anode with excellent cyclic performance for lithium-ion battery

NASA Astrophysics Data System (ADS)

Li, Xiao; Tian, Xiaodong; Yang, Tao; Wang, Wei; Song, Yan; Guo, Quangui; Liu, Zhanjun

2018-05-01

Inferior cycling stability and rate performance respectively caused by rigorous volume change and poor electrical conductivity were the main challenge of state-of-the-art Silicon-based electrode. In this work, silylated functionalized exfoliated graphite oxide (EGO)/silicon@amorphous carbon (3-APTS-EGO/Si@C) was synthesized by adopting silane as intermediate to connect Si particles with EGO sheets followed by introduction of amorphous carbon. The result suggested that 3-Aminopropyltriethoxysilan connected the EGO sheets and Si nanoparticles via covalent bonds. Owing to the strong covalent interaction and the synergistic effect between the silicon, EGO sheets and amorphous carbon, 3-APTS-EGO/Si@C composite possessed a high capacity of 774 mAh g-1 even after 450 cycles at 0.4 A g-1 with the retention capacity of 97%. This work also provided an effective strategy to improve the long cycling life performance of Si-based electrode.

Related Instructional Material for Electrical Apprentice Technical Training. Student Worksheets. Series No. A (First Year). Revised to Meet 1978 Electrical Code.

ERIC Educational Resources Information Center

North Carolina State Dept. of Community Colleges, Raleigh.

Information sheets and student worksheets for thirty-six lessons designed for a first-year electrical apprentice technical training program are presented in this workbook. The information sheets provide summary information about the lesson topics and the worksheets contain problems to be solved and questions to be answered relating to each lesson.…

Related Instructional Material for Electrical Apprentice Technical Training. Student Worksheets. Series No. B (Second Year). Revised to Meet 1978 Electrical Code.

ERIC Educational Resources Information Center

North Carolina State Dept. of Community Colleges, Raleigh.

Information sheets and student worksheets for twenty-eight lesson plans designed for a second-year electrical apprentice technical training program are presented in this workbook. The information sheets provide summary information about the lesson topics and the worksheets contain problems to be solved and questions to be answered relating to each…

Rotating magnetizations in electrical machines: Measurements and modeling

NASA Astrophysics Data System (ADS)

Thul, Andreas; Steentjes, Simon; Schauerte, Benedikt; Klimczyk, Piotr; Denke, Patrick; Hameyer, Kay

2018-05-01

This paper studies the magnetization process in electrical steel sheets for rotational magnetizations as they occur in the magnetic circuit of electrical machines. A four-pole rotational single sheet tester is used to generate the rotating magnetic flux inside the sample. A field-oriented control scheme is implemented to improve the control performance. The magnetization process of different non-oriented materials is analyzed and compared.

Immobilization of silver nanoparticles on exfoliated mica nanosheets to form highly conductive nanohybrid films

NASA Astrophysics Data System (ADS)

Chiu, Chih-Wei; Ou, Gang-Bo; Tsai, Yu-Hsuan; Lin, Jiang-Jen

2015-11-01

Highly electrically conductive films were prepared by coating organic/inorganic nanohybrid solutions with a polymeric dispersant and exfoliated mica nanosheets (Mica) on which silver nanoparticles (AgNPs) had been dispersed in various components. Transmission electronic microscopy showed that the synthesized AgNPs had a narrow size distribution and a diameter of approximately 20 nm. Furthermore, a 60 μm thick film with a sheet resistance as low as 4.5 × 10-2 Ω/sq could be prepared by controlling the heating temperature and by using AgNPs/POE-imide/Mica in a weight ratio of 20:20:1. During the heating process, the surface color of the hybrid film changed from dark golden to white, suggesting the accumulation of the AgNPs through surface migration and their melting to form an interconnected network. These nanohybrid films have potential for use in various electrically conductive devices.

Heat treatment effect on the electronic and magnetic structures of nanographene sheets investigated through electron spectroscopy and conductance measurements.

PubMed

Takashiro, Jun-ichi; Kudo, Yasuhiko; Kaneko, Satoshi; Takai, Kazuyuki; Ishii, Takafumi; Kyotani, Takashi; Enoki, Toshiaki; Kiguchi, Manabu

2014-04-28

The heat treatment effect on the electronic and magnetic structures of a disordered network of nanographene sheets has been investigated by in situ measurements of X-ray photoemission spectroscopy, near-edge X-ray absorption fine structure (NEXAFS), and electrical conductance, together with temperature-programmed desorption measurements. Oxygen-containing functional groups bonded to nanographene edges in the pristine sample are almost completely decomposed under heat treatment up to 1300-1500 K, resulting in the formation of edges primarily terminated by hydrogen. The removal of the oxygen-containing groups enhances the conductance owing to the decrease in the electron transport barriers between nanographene sheets. Heat treatment above 1500 K removes also the hydrogen atoms from the edges, promoting the successive fusion of nanographene sheets at the expense of edges. The decrease in the π* peak width in NEXAFS indicates the progress of the fusion reaction, that is, the extension of the π-conjugation, which agrees with the increase in the orbital susceptibility previously reported. The fusion leads to the formation of local π/sp(2) bridges between nanographene sheets and brings about an insulator-to-metal transition at 1500-1600 K, at which the bridge network becomes infinite. As for the magnetism, the intensity of the edge state peak in NEXAFS, which corresponds to the number of the spin-polarized edge states, decreases above 1500 K, though the effective edge-state spin density per edge state starts decreasing at approximately 200 K lower than the temperature of the edge state peak change. This disagreement indicates the development of antiferromagnetic short range ordering as a precursor of a spin glass state near the insulator-metal transition, at which the random network of inter-nanographene-sheet exchange interactions strengthened with the formation of the π/sp(2) bridges becomes infinite.

Solid oxide fuel cell with monolithic core

DOEpatents

McPheeters, Charles C.; Mrazek, Franklin C.

1988-01-01

A solid oxide fuel cell in which fuel and oxidant gases undergo an electrochemical reaction to produce an electrical output includes a monolithic core comprised of a corrugated conductive sheet disposed between upper and lower generally flat sheets. The corrugated sheet includes a plurality of spaced, parallel, elongated slots which form a series of closed, linear, first upper and second lower gas flow channels with the upper and lower sheets within which a fuel gas and an oxidant gas respectively flow. Facing ends of the fuel cell are generally V-shaped and provide for fuel and oxidant gas inlet and outlet flow, respectively, and include inlet and outlet gas flow channels which are continuous with the aforementioned upper fuel gas and lower oxidant gas flow channels. The upper and lower flat sheets and the intermediate corrugated sheet are preferably comprised of ceramic materials and are securely coupled together such as by assembly in the green state and sintering together during firing at high temperatures. A potential difference across the fuel cell, or across a stacked array of similar fuel cells, is generated when an oxidant gas such as air and a fuel such as hydrogen gas is directed through the fuel cell at high temperatures, e.g., between 700.degree. C. and 1100.degree. C.

Solid oxide fuel cell with monolithic core

DOEpatents

McPheeters, C.C.; Mrazek, F.C.

1988-08-02

A solid oxide fuel cell in which fuel and oxidant gases undergo an electrochemical reaction to produce an electrical output includes a monolithic core comprised of a corrugated conductive sheet disposed between upper and lower generally flat sheets. The corrugated sheet includes a plurality of spaced, parallel, elongated slots which form a series of closed, linear, first upper and second lower gas flow channels with the upper and lower sheets within which a fuel gas and an oxidant gas respectively flow. Facing ends of the fuel cell are generally V-shaped and provide for fuel and oxidant gas inlet and outlet flow, respectively, and include inlet and outlet gas flow channels which are continuous with the aforementioned upper fuel gas and lower oxidant gas flow channels. The upper and lower flat sheets and the intermediate corrugated sheet are preferably comprised of ceramic materials and are securely coupled together such as by assembly in the green state and sintering together during firing at high temperatures. A potential difference across the fuel cell, or across a stacked array of similar fuel cells, is generated when an oxidant gas such as air and a fuel such as hydrogen gas is directed through the fuel cell at high temperatures, e.g., between 700 C and 1,100 C. 8 figs.

Into the groove: instructive silk-polypyrrole films with topographical guidance cues direct DRG neurite outgrowth.

PubMed

Hardy, John G; Khaing, Zin Z; Xin, Shangjing; Tien, Lee W; Ghezzi, Chiara E; Mouser, David J; Sukhavasi, Rushi C; Preda, Rucsanda C; Gil, Eun S; Kaplan, David L; Schmidt, Christine E

2015-01-01

Instructive biomaterials capable of controlling the behaviour of the cells are particularly interesting scaffolds for tissue engineering and regenerative medicine. Novel biomaterials are particularly important in societies with rapidly aging populations, where demand for organ/tissue donations is greater than their supply. Herein we describe the preparation of electrically conductive silk film-based nerve tissue scaffolds that are manufactured using all aqueous processing. Aqueous solutions of Bombyx mori silk were cast on flexible polydimethylsiloxane substrates with micrometer-scale grooves on their surfaces, allowed to dry, and annealed to impart β-sheets to the silk which assures that the materials are stable for further processing in water. The silk films were rendered conductive by generating an interpenetrating network of polypyrrole and polystyrenesulfonate in the silk matrix. Films were incubated in an aqueous solution of pyrrole (monomer), polystyrenesulfonate (dopant) and iron chloride (initiator), after which they were thoroughly washed to remove low molecular weight components (monomers, initiators, and oligomers) and dried, yielding conductive films with sheet resistances of 124 ± 23 kΩ square(-1). The micrometer-scale grooves that are present on the surface of the films are analogous to the natural topography in the extracellular matrix of various tissues (bone, muscle, nerve, skin) to which cells respond. Dorsal root ganglions (DRG) adhere to the films and the grooves in the surface of the films instruct the aligned growth of processes extending from the DRG. Such materials potentially enable the electrical stimulation (ES) of cells cultured on them, and future in vitro studies will focus on understanding the interplay between electrical and topographical cues on the behaviour of cells cultured on them.

Novel degradable co-polymers of polypyrrole support cell proliferation and enhance neurite out-growth with electrical stimulation.

PubMed

Durgam, Hymavathi; Sapp, Shawn; Deister, Curt; Khaing, Zin; Chang, Emily; Luebben, Silvia; Schmidt, Christine E

2010-01-01

Synthetic polymers such as polypyrrole (PPy) are gaining significance in neural studies because of their conductive properties. We evaluated two novel biodegradable block co-polymers of PPy with poly(epsilon-caprolactone) (PCL) and poly(ethyl cyanoacrylate) (PECA) for nerve regeneration applications. PPy-PCL and PPy-PECA co-polymers can be processed from solvent-based colloidal dispersions and have essentially the same or greater conductivity (32 S/cm for PPy-PCL, 19 S/cm for PPy-PECA) compared to the PPy homo-polymer (22 S/cm). The PPy portions of the co-polymers permit electrical stimulation whereas the PCL or PECA blocks enable degradation by hydrolysis. For in vitro tests, films were prepared on polycarbonate sheets by air brushing layers of dispersions and pressing the films. We characterized the films for hydrolytic degradation, electrical conductivity, cell proliferation and neurite extension. The co-polymers were sufficient to carry out electrical stimulation of cells without the requirement of a metallic conductor underneath the co-polymer film. In vitro electrical stimulation of PPy-PCL significantly increased the number of PC12 cells bearing neurites compared to unstimulated PPy-PCL. For in vivo experiments, the PPy co-polymers were coated onto the inner walls of nerve guidance channels (NGCs) made of the commercially available non-conducting biodegradable polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV). The NGCs were implanted in a 10 mm defect made in the sciatic nerve of rats, and harvested after 8 weeks. Histological staining showed axonal growth. The studies indicated that these new conducting degradable biomaterials have good biocompatibility and support proliferation and growth of PC12 cells in vitro (with and without electrical stimulation) and neurons in vivo (without electrical stimulation).

Production of quasi-2D graphene nanosheets through the solvent exfoliation of pitch-based carbon fiber

NASA Astrophysics Data System (ADS)

Yeon, Youngju; Lee, Mi Yeon; Kim, Sang Youl; Lee, Jihoon; Kim, Bongsoo; Park, Byoungnam; In, Insik

2015-09-01

Stable dispersion of quasi-2D graphene sheets with a concentration up to 1.27 mg mL-1 was prepared by sonication-assisted solvent exfoliation of pitch-based carbon fiber in N-methyl pyrrolidone with the mass yield of 2.32%. Prepared quasi-2D graphene sheets have multi-layered 2D plate-like morphology with rich inclusions of graphitic carbons, a low number of structural defects, and high dispersion stability in aprotic polar solvents, and facilitate the utilization of quasi-2D graphene sheets prepared from pitch-based carbon fiber for various electronic and structural applications. Thin films of quasi-2D graphene sheets prepared by vacuum filtration of the dispersion of quasi-2D graphene sheets demonstrated electrical conductivity up to 1.14 × 104 Ω/□ even without thermal treatment, which shows that pitch-based carbon fiber might be useful as the source of graphene-related nanomaterials. Because pitch-based carbon fiber could be prepared from petroleum pitch, a very cheap structural material for the pavement of asphalt roads, our approach might be promising for the mass production of quasi-2D graphene nanomaterials.

Electrical and optical properties of sub-10 nm nickel silicide films for silicon solar cells

NASA Astrophysics Data System (ADS)

Brahmi, Hatem; Ravipati, Srikanth; Yarali, Milad; Shervin, Shahab; Wang, Weijie; Ryou, Jae-Hyun; Mavrokefalos, Anastassios

2017-01-01

Highly conductive and transparent films of ultra-thin p-type nickel silicide films have been prepared by RF magnetron sputtering of nickel on silicon substrates followed by rapid thermal annealing in an inert environment in the temperature range 400-600 °C. The films are uniform throughout the wafer with thicknesses in the range of 3-6 nm. The electrical and optical properties are presented for nickel silicide films with varying thickness. The Drude-Lorentz model and Fresnel equations were used to calculate the dielectric properties, sheet resistance, absorption and transmission of the films. These ultrathin nickel silicide films have excellent optoelectronic properties for p-type contacts with optical transparencies up to 80% and sheet resistance as low as ~0.15 µΩ cm. Furthermore, it was shown that the use of a simple anti-reflection (AR) coating can recover most of the reflected light approaching the values of a standard Si solar cell with the same AR coating. Overall, the combination of ultra-low thickness, high transmittance, low sheet resistance and ability to recover the reflected light by utilizing standard AR coating makes them ideal for utilization in silicon based photovoltaic technologies as a p-type transparent conductor.

Low Cost, Single Layer Replacement for the Back-Sheet and Encapsulant Layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kempe, M. D.; Thapa, P.

2008-01-01

Ethylene propylene diene monomer (EPDM) based polymers have been formulated for specific use in photovoltaic modules to produce better performance and longer term stability at a lower cost than standard materials. EPDM formulations are advantageous over ethylene vinyl-acetate (EVA) because they can use the same lamination/cure cycle as EVA, they do not need a second back-sheet protective material (e.g. PET/Tedlar), they have a lower glass transition temperature, no melting transition, more constant mechanical moduli as a function of temperature, they are less polar than EVA (provides better corrosion protection), and they have excellent damp heat (85 C/85% relative humidity) resistancemore » against delamination. Module designs typically use EVA on the back side of cells despite the fact that transparency is not advantageous. We have developed a single encapsulant layer that will replace standard module back-sheet constructions consisting of EVA/PET/Tedlar. Because a single low-cost material layer is used, it will provide a significant materials cost savings of about $6 to $8/m{sup 2} as compared to traditional back-sheets. Electrical insulation tests were conducted using 0.85 mm thick stainless steel sheets as a model for a cell. It was found that a polymer layer thickness of about 0.33mm provided better high voltage electrical insulation than a combined film of Tedla (0.038 mm)/PET (0.051 mm)/EVA (0.55 mm). When formulated with a white pigment, reflectivity was comparable to Tedlar{trademark}. Upon accelerated exposure to light at 60C and 60% RH it was found that an EVA layer in front of these materials would decompose before significant yellowing and delamination of the back EPDM layer occurs.« less

Strain induced chemical potential difference between monolayer graphene sheets.

PubMed

Zhang, Yupeng; Luo, Chengzhi; Li, Weiping; Pan, Chunxu

2013-04-07

Monolayer graphene sheets were deposited on a transparent and flexible polydimethylsiloxane (PDMS) substrate, and a tensile strain was loaded by stretching the substrate in one direction. It was found that an electric potential difference between stretched and static monolayer graphene sheets reached 8 mV when the strain was 5%. Theoretical calculations for the band structure and total energy revealed an alternative way to experimentally tune the band gap of monolayer graphene, and induce the generation of electricity.

Self-propulsion of a planar electric or magnetic microbot immersed in a polar viscous fluid

NASA Astrophysics Data System (ADS)

Felderhof, B. U.

2011-05-01

A planar sheet immersed in an electrically polar liquid like water can propel itself by means of a plane wave charge density propagating in the sheet. The corresponding running electric wave polarizes the fluid and causes an electrical torque density to act on the fluid. The sheet is convected by the fluid motion resulting from the conversion of rotational particle motion, generated by the torque density, into translational fluid motion by the mechanism of friction and spin diffusion. Similarly, a planar sheet immersed in a magnetic ferrofluid can propel itself by means of a plane wave current density in the sheet and the torque density acting on the fluid corresponding to the running wave magnetic field and magnetization. The effect is studied on the basis of the micropolar fluid equations of motion and Maxwell’s equations of electrostatics or magnetostatics, respectively. An analytic expression is derived for the velocity of the sheet by perturbation theory to second order in powers of the amplitude of the driving charge or current density. Under the assumption that the equilibrium magnetic equation of state may be used in linearized form and that higher harmonics than the first may be neglected, a set of self-consistent integral equations is derived which can be solved numerically by iteration. In typical situations the second-order perturbation theory turns out to be quite accurate.

Electron Cooling and Isotropization during Magnetotail Current Sheet Thinning: Implications for Parallel Electric Fields

NASA Astrophysics Data System (ADS)

Lu, San; Artemyev, A. V.; Angelopoulos, V.

2017-11-01

Magnetotail current sheet thinning is a distinctive feature of substorm growth phase, during which magnetic energy is stored in the magnetospheric lobes. Investigation of charged particle dynamics in such thinning current sheets is believed to be important for understanding the substorm energy storage and the current sheet destabilization responsible for substorm expansion phase onset. We use Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and C observations in 2008 and 2009 at 18 - 25 RE to show that during magnetotail current sheet thinning, the electron temperature decreases (cooling), and the parallel temperature decreases faster than the perpendicular temperature, leading to a decrease of the initially strong electron temperature anisotropy (isotropization). This isotropization cannot be explained by pure adiabatic cooling or by pitch angle scattering. We use test particle simulations to explore the mechanism responsible for the cooling and isotropization. We find that during the thinning, a fast decrease of a parallel electric field (directed toward the Earth) can speed up the electron parallel cooling, causing it to exceed the rate of perpendicular cooling, and thus lead to isotropization, consistent with observation. If the parallel electric field is too small or does not change fast enough, the electron parallel cooling is slower than the perpendicular cooling, so the parallel electron anisotropy grows, contrary to observation. The same isotropization can also be accomplished by an increasing parallel electric field directed toward the equatorial plane. Our study reveals the existence of a large-scale parallel electric field, which plays an important role in magnetotail particle dynamics during the current sheet thinning process.

Residual stress evaluation by Barkhausen signals with a magnetic field sensor for high efficiency electrical motors

NASA Astrophysics Data System (ADS)

Tsuchida, Yuji; Enokizono, Masato

2018-04-01

The iron loss of industrial motors increases by residual stress during manufacturing processes. It is very important to make clear the distribution of the residual stress in the motor cores to reduce the iron loss in the motors. Barkhausen signals which occur on electrical steel sheets can be used for the evaluation of the residual stress because they are very sensitive to the material properties. Generally, a B-sensor is used to measure Barkhausen signals, however, we developed a new H-sensor to measure them and applied it into the stress evaluation. It is supposed that the Barkhausen signals by using a H-sensor can be much effective to the residual stress on the electrical steel sheets by referring our results regarding to the stress evaluations. We evaluated the tensile stress of the electrical steel sheets by measuring Barkhausen signals by using our developed H-sensor for high efficiency electrical motors.

Fabrication of electric papers of graphene nanosheet shelled cellulose fibres by dispersion and infiltration as flexible electrodes for energy storage

NASA Astrophysics Data System (ADS)

Kang, Yan-Ru; Li, Ya-Li; Hou, Feng; Wen, Yang-Yang; Su, Dong

2012-05-01

An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω □-1 and a conductivity of 11.6 S m-1. The application of the composite paper as a flexible double layer supercapacitor in an organic electrolyte (LiPF6) displays a high capacity of 252 F g-1 at a current density of 1 A g-1 with respect to GNS. Moreover, the paper can be used as the anode in a lithium battery, showing distinct charge and discharge performances. The simple process for synthesising the GNS functionalized cellulose papers is attractive for the development of high performance papers for electrical, electrochemical and multifunctional applications.An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω □-1 and a conductivity of 11.6 S m-1. The application of the composite paper as a flexible double layer supercapacitor in an organic electrolyte (LiPF6) displays a high capacity of 252 F g-1 at a current density of 1 A g-1 with respect to GNS. Moreover, the paper can be used as the anode in a lithium battery, showing distinct charge and discharge performances. The simple process for synthesising the GNS functionalized cellulose papers is attractive for the development of high performance papers for electrical, electrochemical and multifunctional applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30318c

Nitrogen doped graphene - Silver nanowire hybrids: An excellent anode material for lithium ion batteries

NASA Astrophysics Data System (ADS)

Nair, Anju K.; Elizabeth, Indu; S, Gopukumar; Thomas, Sabu; M. S, Kala; Kalarikkal, Nandakumar

2018-01-01

We present an in-situ polyol assisted synthesis approach for the preparation of silver nanowires (AgNW) over the nitrogen doped graphene (NG) sheets and has been tested as a viable LIBs anode material for the first time. The use of NG serves as nucleation sites, thereby facilitating the growth of AgNWs. The specific material design of the as-prepared NG-AgNW hybrids involves some advantages, including a continuous AgNW-graphene conducting network. Since AgNWs are electrically conductive, it provides an electrical contact with NG sheets which can effectively help the charge transport process and limit the variations in volume during the lithiation/de-lithiation processes. Apart from this, the insertion of metallic Ag nanowires into a percolated NG network increases the interlayer distance of NG sheets and prevent its restacking. Moreover, the more porous nature of the hybrid structure accommodating the large volume changes of AgNWs. As an anode material for LIBs, the NG-AgNW hybrid displays a remarkable initial discharge capacity of 1215 mAh g-1 and attains a stable capacity of 724 mAh g-1 at a current density of 100 mA g-1 after 50 cycles. The electrode exhibits a stable reversible capacity of 714, 634, 550 and 464 mA h g-1 at 0.1, 0.2, 0.5, 1 Ag-1 respectively. The reversible capacity (710 mAh g-1) at 0.1 Ag-1 is recovered after the cycling at various current densities confirming outstanding rate performance of the material. In addition, the coulombic efficiency, the NG-AgNW anode retains nearly 99% after the second cycle, further indicating its excellent reversibility. The hybrid material exhibits better cycling stability, greater rate capability, capacity retention and superior reversible capacity than that of bare AgNW and NG sheets. Our smart design will pave way for the development of efficient electrode materials for high capacity and long cycle life LIBs.

Human Induced Pluripotent Stem Cell-Derived Cardiac Cell Sheets Expressing Genetically Encoded Voltage Indicator for Pharmacological and Arrhythmia Studies.

PubMed

Shaheen, Naim; Shiti, Assad; Huber, Irit; Shinnawi, Rami; Arbel, Gil; Gepstein, Amira; Setter, Noga; Goldfracht, Idit; Gruber, Amit; Chorna, Snizhanna V; Gepstein, Lior

2018-06-05

Fulfilling the potential of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes for studying conduction and arrhythmogenesis requires development of multicellular models and methods for long-term repeated tissue phenotyping. We generated confluent hiPSC-derived cardiac cell sheets (hiPSC-CCSs), expressing the genetically encoded voltage indicator ArcLight. ArcLight-based optical mapping allowed generation of activation and action-potential duration (APD) maps, which were validated by mapping the same hiPSC-CCSs with the voltage-sensitive dye, Di-4-ANBDQBS. ArcLight mapping allowed long-term assessment of electrical remodeling in the hiPSC-CCSs and evaluation of drug-induced conduction slowing (carbenoxolone, lidocaine, and quinidine) and APD prolongation (quinidine and dofetilide). The latter studies also enabled step-by-step depiction of drug-induced arrhythmogenesis ("torsades de pointes in the culture dish") and its prevention by MgSO 4 and rapid pacing. Phase-mapping analysis allowed biophysical characterization of spiral waves induced in the hiPSC-CCSs and their termination by electrical cardioversion and overdrive pacing. In conclusion, ArcLight mapping of hiPSC-CCSs provides a powerful tool for drug testing and arrhythmia investigation. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

h-BN/graphene van der Waals vertical heterostructure: a fully spin-polarized photocurrent generator.

PubMed

Tao, Xixi; Zhang, Lei; Zheng, Xiaohong; Hao, Hua; Wang, Xianlong; Song, Lingling; Zeng, Zhi; Guo, Hong

2017-12-21

By constructing transport junctions using graphene-based van der Waals (vdW) heterostructures in which a zigzag-edged graphene nanoribbon (ZGNR) is sandwiched between two hexagonal boron-nitride sheets, we computationally demonstrate a new scheme for generating perfect spin-polarized quantum transport in ZGNRs by light irradiation. The mechanism lies in the lift of spin degeneracy of ZGNR induced by the stagger potential it receives from the BN sheets and the subsequent possibility of single spin excitation of electrons from the valence band to the conduction band by properly tuning the photon energy. This scheme is rather robust in that we always achieve desirable results irrespective of whether we decrease or increase the interlayer distance by applying compressive or tensile strain vertically to the sheets or shift the BN sheets in-plane relative to the graphene nanoribbons. More importantly, this scheme overcomes the long-standing difficulties in traditional ways of using solely electrical field or chemical modification for obtaining half-metallic transport in ZGNRs and thus paves a more feasible way for their application in spintronics.

Field Emission Properties of Carbon Nanotube Fibers and Sheets for a High Current Electron Source

NASA Astrophysics Data System (ADS)

Christy, Larry

Field emission (FE) properties of carbon nanotube (CNT) fibers from Rice University and the University of Cambridge have been studied for use within a high current electron source for a directed energy weapon. Upon reviewing the performance of these two prevalent CNT fibers, cathodes were designed with CNT fibers from the University of Cincinnati Nanoworld Laboratory. Cathodes composed of a single CNT fiber, an array of three CNT fibers, and a nonwoven CNT sheet were investigated for FE properties; the goal was to design a cathode with emission current in excess of 10 mA. Once the design phase was complete, the cathode samples were fabricated, characterized, and then analyzed to determine FE properties. Electrical conductivity of the CNT fibers was characterized with a 4-probe technique. FE characteristics were measured in an ultra-high vacuum chamber at Wright-Patterson Air Force Base. The arrayed CNT fiber and the enhanced nonwoven CNT sheet emitter design demonstrated the most promising FE properties. Future work will include further analysis and cathode design using this nonwoven CNT sheet material to increase peak current performance during electron emission.

Modulating the band gap of a boron nitride bilayer with an external electric field for photocatalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Y. R.; Cao, J. X., E-mail: jxcao@xtu.edu.cn; Zhang, Y.

2016-05-21

By virtue of first principle calculations, we propose an approach to reduce the band gap of layered semiconductors through the application of external electric fields for photocatalysis. As a typical example, the band gap of a boron nitride (BN) bilayer was reduced in the range from 4.45 eV to 0.3 eV by varying the external electric field strength. More interestingly, it is found that the uppermost valence band and the lowest conduction band are dominated by the N-p{sub z} and B-p{sub z} from different layers of the BN sheet, which suggests a wonderful photoexcited electron and hole separation system for photocatalysis. Ourmore » results imply that the strong external electric field can present an abrupt polarized surface.« less

Electrochemical cell with high conductivity glass electrolyte

DOEpatents

Nelson, P.A.; Bloom, I.D.; Roche, M.F.

1986-04-17

A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with an ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material.

Electrochemical cell with high conductivity glass electrolyte

DOEpatents

Nelson, P.A.; Bloom, I.D.; Roche, M.F.

1987-04-21

A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with a ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material. 6 figs.

Electrochemical cell with high conductivity glass electrolyte

DOEpatents

Nelson, Paul A.; Bloom, Ira D.; Roche, Michael F.

1987-01-01

A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with a ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erkaev, N. V.; Semenov, V. S.; Biernat, H. K.

Hall magnetohydrodynamic model is investigated for current sheet flapping oscillations, which implies a gradient of the normal magnetic field component. For the initial undisturbed current sheet structure, the normal magnetic field component is assumed to have a weak linear variation. The profile of the electric current velocity is described by hyperbolic functions with a maximum at the center of the current sheet. In the framework of this model, eigenfrequencies are calculated as functions of the wave number for the ''kink'' and ''sausage'' flapping wave modes. Because of the Hall effects, the flapping eigenfrequency is larger for the waves propagating alongmore » the electric current, and it is smaller for the opposite wave propagation with respect to the current. The asymmetry of the flapping wave propagation, caused by Hall effects, is pronounced stronger for thinner current sheets. This is due to the Doppler effect related to the electric current velocity.« less

Effects of electric current on individual graphene oxide sheets combining in situ transmission electron microscopy and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Martín, Gemma; Varea, Aïda; Cirera, Albert; Estradé, Sònia; Peiró, Francesca; Cornet, Albert

2018-07-01

Graphene oxide (GO) is currently the object of extensive research because of its potential use in mass production of graphene-based materials, but also due to its tunability which holds great promise for new nanoscale electronic devices and sensors. To obtain a better understanding of the role of GO in electronic nano-devices, the elucidation of the effects of electrical current on a single GO sheet is of great interest. In this work, in situ transmission electron microscopy is used to study the effects of the electrical current flow through single GO sheets using an scanning tunneling microscope holder. In order to correlate the applied current with the structural properties of GO, Raman spectroscopy is carried out and data analysis is used to obtain information regarding the reduction grade and the disorder degree of the GO sheets before and after the application of current.

Effects of electric current on individual graphene oxide sheets combining in situ transmission electron microscopy and Raman spectroscopy.

PubMed

Martín, Gemma; Varea, Aïda; Cirera, Albert; Estradé, Sònia; Peiró, Francesca; Cornet, Albert

2018-04-17

Graphene oxide (GO) is currently the object of extensive research because of its potential use in mass production of graphene-based materials, but also due to its tunability which holds great promise for new nanoscale electronic devices and sensors. To obtain a better understanding of the role of GO in electronic nano-devices, the elucidation of the effects of electrical current on a single GO sheet is of great interest. In this work, in situ transmission electron microscopy is used to study the effects of the electrical current flow through single GO sheets using an scanning tunneling microscope holder. In order to correlate the applied current with the structural properties of GO, Raman spectroscopy is carried out and data analysis is used to obtain information regarding the reduction grade and the disorder degree of the GO sheets before and after the application of current.

Analysis of interlocking performances on non-oriented electrical steels

NASA Astrophysics Data System (ADS)

Liu, Li-Hsiang; Liu, Lee-Cheng

2018-05-01

In order to reduce energy loss in motor, applications of high-efficiency non-oriented electrical steel sheets and optimal laminating process are both important elements. The motor core loss deterioration is influenced by a number of factors, such as flux distribution, stress and strain, space harmonics, temperature, and short circuits between lamination. In conventional clamping method, steel sheets are laminated via interlocking or welding in general manner. The measured energy loss by welding was much larger than that by interlocking. Therefore, interlocking is well known and usually employed with benefit of easy conducting. The protuberance shapes affected the fastening strength. Generally, the intensity of rectangular type is stronger than the circular counterparts. However, the circular interlocking has better magnetic characteristics. To clarify the method effectiveness, interlocking performances regarding fastened strength and magnetic deterioration by lamination were investigated. The key parameters of protuberance shape and forming depth were designed. Precisely manufacturing operation was applied to avoid interlocking failure. Magnetic properties largely influenced by clamping method are crucial to minimizing the magnetic deterioration during laminating procedure. Several experiments for various processing conditions were undertaken, and the quantification results showed the rectangular interlocking had better fastened strength but worsened iron loss comparing with the circular arrangement. To acquire the comprehensive mechanical and electrical identities for electrical steel lamination, deliberate producing conditions regarding minimizing the magnetic deterioration should be adopted prudently.

One-step synthesis of graphene nanoribbon-MnO2 hybrids and their all-solid-state asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Mingkai; Tjiu, Weng Weei; Pan, Jisheng; Zhang, Chao; Gao, Wei; Liu, Tianxi

2014-03-01

Three-dimensional (3D) hierarchical hybrid nanomaterials (GNR-MnO2) of graphene nanoribbons (GNR) and MnO2 nanoparticles have been prepared via a one-step method. GNR, with unique features such as high aspect ratio and plane integrity, has been obtained by longitudinal unzipping of multi-walled carbon nanotubes (CNTs). By tuning the amount of oxidant used, different mass loadings of MnO2 nanoparticles have been uniformly deposited on the surface of GNRs. Asymmetric supercapacitors have been fabricated with the GNR-MnO2 hybrid as the positive electrode and GNR sheets as the negative electrode. Due to the desirable porous structure, excellent electrical conductivity, as well as high rate capability and specific capacitances of both the GNR and GNR-MnO2 hybrid, the optimized GNR//GNR-MnO2 asymmetric supercapacitor can be cycled reversibly in an enlarged potential window of 0-2.0 V. In addition, the fabricated GNR//GNR-MnO2 asymmetric supercapacitor exhibits a significantly enhanced maximum energy density of 29.4 W h kg-1 (at a power density of 12.1 kW kg-1), compared with that of the symmetric cells based on GNR-MnO2 hybrids or GNR sheets. This greatly enhanced energy storage ability and high rate capability can be attributed to the homogeneous dispersion and excellent pseudocapacitive performance of MnO2 nanoparticles and the high electrical conductivity of the GNRs.Three-dimensional (3D) hierarchical hybrid nanomaterials (GNR-MnO2) of graphene nanoribbons (GNR) and MnO2 nanoparticles have been prepared via a one-step method. GNR, with unique features such as high aspect ratio and plane integrity, has been obtained by longitudinal unzipping of multi-walled carbon nanotubes (CNTs). By tuning the amount of oxidant used, different mass loadings of MnO2 nanoparticles have been uniformly deposited on the surface of GNRs. Asymmetric supercapacitors have been fabricated with the GNR-MnO2 hybrid as the positive electrode and GNR sheets as the negative electrode. Due to the desirable porous structure, excellent electrical conductivity, as well as high rate capability and specific capacitances of both the GNR and GNR-MnO2 hybrid, the optimized GNR//GNR-MnO2 asymmetric supercapacitor can be cycled reversibly in an enlarged potential window of 0-2.0 V. In addition, the fabricated GNR//GNR-MnO2 asymmetric supercapacitor exhibits a significantly enhanced maximum energy density of 29.4 W h kg-1 (at a power density of 12.1 kW kg-1), compared with that of the symmetric cells based on GNR-MnO2 hybrids or GNR sheets. This greatly enhanced energy storage ability and high rate capability can be attributed to the homogeneous dispersion and excellent pseudocapacitive performance of MnO2 nanoparticles and the high electrical conductivity of the GNRs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06650a

Carboxymethyl chitosan/conducting polymer as water-soluble composite binder for LiFePO4 cathode in lithium ion batteries

NASA Astrophysics Data System (ADS)

Zhong, Haoxiang; He, Aiqin; Lu, Jidian; Sun, Minghao; He, Jiarong; Zhang, Lingzhi

2016-12-01

A water-soluble conductive composite binder consisting of carboxymethyl chitosan (CCTS) as a binder and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a conduction-promoting agent is reported for the LiFePO4 (LFP) cathode in Li-ion batteries. The introduction of conductive PEDOT:PSS as a conductive composite binder facilitates the formation of homogeneous and continuous conducting bridges throughout the electrode and raises the compaction density of the electrode sheet by decreasing the amounts of the commonly used conducting agent of acetylene black. The optimized replacement ratios of acetylene black with PEDOT:PSS (acetylene black/PEDOT:PSS = 1:1, by weight) are obtained by measuring electrical conductivity, peel strength and compaction density of the electrode sheets. The LFP half-cell with the optimized conductive binder exhibits better cycling and rate performance and more favorable electrochemical kinetics than that using only acetylene black conducting agent. The pilot application of PEDOT:PSS/CCTS binder in 10 Ah CCTS-LFP prismatic cell exhibits a comparable cycling performance, retaining 89.7% of capacity at 1 C/2 C (charge/discharge) rate as compared with 90% for commercial PVDF-LFP over 1000 cycles, and better rate capability than that of commercial PVDF-LFP, retaining 98% capacity of 1 C at 7 C rate as compared with 95.4% for PVDF-LFP.

Polar Spacecraft Based Comparisons of Intense Electric Fields and Poynting Flux Near and Within the Plasma Sheet-Tail Lobe Boundary to UVI Images: An Energy Source for the Aurora

NASA Technical Reports Server (NTRS)

Wygant, J. R.; Keiling, A.; Cattell, C. A.; Johnson, M.; Lysak, R. L.; Temerin, M.; Mozer, F. S.; Kletzing, C. A.; Scudder, J. D.; Peterson, W.;

Polar spacecraft based comparisons of intense electric fields and Poynting flux near and within the plasma sheet-tail lobe boundary to UVI images: An energy source for the aurora

NASA Astrophysics Data System (ADS)

Wygant, J. R.; Keiling, A.; Cattell, C. A.; Johnson, M.; Lysak, R. L.; Temerin, M.; Mozer, F. S.; Kletzing, C. A.; Scudder, J. D.; Peterson, W.; Russell, C. T.; Parks, G.; Brittnacher, M.; Germany, G.; Spann, J.

2000-08-01

In this paper, we present measurements from two passes of the Polar spacecraft of intense electric and magnetic field structures associated with Alfven waves at and within the outer boundary of the plasma sheet at geocentric distances of 4-6 RE near local midnight. The electric field variations have maximum values exceeding 100 mV/m and are typically polarized approximately normal to the plasma sheet boundary. The electric field structures investigated vary over timescales (in the spacecraft frame) ranging from 1 to 30 s. They are associated with strong magnetic field fluctuations with amplitudes of 10-40 nT which lie predominantly in the plane of the plasma sheet and are perpendicular to the local magnetic field. The Poynting flux associated with the perturbation fields measured at these altitudes is about 1-2 ergs cm-2 s-1 and is directed along the average magnetic field direction toward the ionosphere. If the measured Poynting flux is mapped to ionospheric altitudes along converging magnetic field lines, the resulting energy flux ranges up to 100 ergs cm-2s-1. These strongly enhanced Poynting fluxes appear to occur in layers which are observed when the spacecraft is magnetically conjugate (to within a 1° mapping accuracy) to intense auroral structures as detected by the Polar UV Imager (UVI). The electron energy flux (averaged over a spatial resolution of 0.5° ) deposited in the ionosphere due to auroral electron beams as estimated from the intensity in the UVI Lyman-Birge-Hopfield-long filters is 15-30 ergs cm-2s-1. Thus there is evidence that these electric field structures provide sufficient Poynting flux to power the acceleration of auroral electrons (as well as the energization of upflowing ions and Joule heating of the ionosphere). During some events the phasing and ratio of the transverse electric and magnetic field variations are consistent with earthward propagation of Alfven surface waves with phase velocities of 4000-10000 km/s. During other events the phase shifts between electric and magnetic fields suggest interference between upward and downward propagating Alfven waves. The E/B ratios are about an order of magnitude larger than typical values of c/Σp, where Σp is the height integrated Pedersen conductivity. The contribution to the total energy flux at these altitudes from Poynting flux associated with Alfven waves is comparable to or larger than the contribution from the particle energy flux and 1-2 orders of magnitude larger than that estimated from the large-scale steady state convection electric field and field-aligned current system.

Effect of supersonic spraying impact velocity on opto-electric properties of transparent conducting flexible films consisting of silver nanowire, ITO, and polyimide multilayers

DOE PAGES

Kim, Tae-Gun; Lee, Jong-Gun; Park, Chan-Woo; ...

2017-12-26

We demonstrate the use of supersonic spraying for the deposition of silver nanowires (AgNWs) on a flexible polyimide (PI) substrate for the formation of transparent and conducting films (TCF) as an alternative to nonflexible ITO (indium tin oxide). The self-fused intersections of the NWs resulted in films with a low sheet resistance (Rs = 31 ..omega../sq) and fairly high transmittance (Tr = 92%) on a glass substrate. The effect of the impact speed of the supersonically sprayed AgNWs on the opto-electric properties of the flexible TCF was evaluated by varying the spray coating conditions. The fabricated films were characterized bymore » X-ray diffraction analysis, atomic force microscopy, ultraviolet-visible spectroscopy, and scanning electron microscopy. Finally, cyclic bending tests were performed on the PI/AgNW films as well as PI/ZnO/indium tin oxide/AgNW films, and the changes in their electrical properties with bending were compared.« less

Effect of annealing over optoelectronic properties of graphene based transparent electrodes

NASA Astrophysics Data System (ADS)

Yadav, Shriniwas; Kaur, Inderpreet

2016-04-01

Graphene, an atom-thick two dimensional graphitic material have led various fundamental breakthroughs in the field of science and technology. Due to their exceptional optical, physical and electrical properties, graphene based transparent electrodes have shown several applications in organic light emitting diodes, solar cells and thin film transistors. Here, we are presenting effect of annealing over optoelectronic properties of graphene based transparent electrodes. Graphene based transparent electrodes have been prepared by wet chemical approach over glass substrates. After fabrication, these electrodes tested for optical transmittance in visible region. Sheet resistance was measured using four probe method. Effect of thermal annealing at 200 °C was studied over optical and electrical performance of these electrodes. Optoelectronic performance was judged from ratio of direct current conductivity to optical conductivity (σdc/σopt) as a figure of merit for transparent conductors. The fabricated electrodes display good optical and electrical properties. Such electrodes can be alternatives for doped metal oxide based transparent electrodes.

Effect of supersonic spraying impact velocity on opto-electric properties of transparent conducting flexible films consisting of silver nanowire, ITO, and polyimide multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Tae-Gun; Lee, Jong-Gun; Park, Chan-Woo

We demonstrate the use of supersonic spraying for the deposition of silver nanowires (AgNWs) on a flexible polyimide (PI) substrate for the formation of transparent and conducting films (TCF) as an alternative to nonflexible ITO (indium tin oxide). The self-fused intersections of the NWs resulted in films with a low sheet resistance (Rs = 31 ..omega../sq) and fairly high transmittance (Tr = 92%) on a glass substrate. The effect of the impact speed of the supersonically sprayed AgNWs on the opto-electric properties of the flexible TCF was evaluated by varying the spray coating conditions. The fabricated films were characterized bymore » X-ray diffraction analysis, atomic force microscopy, ultraviolet-visible spectroscopy, and scanning electron microscopy. Finally, cyclic bending tests were performed on the PI/AgNW films as well as PI/ZnO/indium tin oxide/AgNW films, and the changes in their electrical properties with bending were compared.« less

Electrically driven rapidly vaporizing foils, wires and strips used for collision welding and sheet metal forming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vivek, Anupam; Daehn, Glenn S; Taber, Geoffrey A

2015-05-05

A method for forming a piece of a sheet metal is performed by positioning a consumable body, made of metal, proximate to the piece of the sheet metal. The consumable body is rapidly vaporized, and the gas pressure generated thereby is directed into the piece of the sheet metal. This results in acceleration of the piece of sheet metal, and it is collided into a stationary body at a velocity, generally in excess of 200 m/s. Depending upon the type of stationary body, the piece of sheet metal is deformed into a predetermined shape or is welded onto the stationarymore » body. The vaporization is accomplished by passing a high current of electricity into the consumable body. The effect of the vaporized metal may be augmented by additional components in the consumable body.« less

Electrical Experiments. VT-214-12-5. Part V. Transformers.

ERIC Educational Resources Information Center

Connecticut State Dept. of Education, Hartford. Div. of Vocational Education.

Designed for high school electronics students, this fifth document in a series of six electrical learning activity packages focuses on transformers. An introductory section gives the objective for the activities, an introduction, and an outline of the content. The remainder of the activity book is comprised of information sheets and job sheets on…

Characteristics of DC electric fields in transient plasma sheet events

NASA Astrophysics Data System (ADS)

Laakso, H. E.; Escoubet, C. P.; Masson, A.

2015-12-01

We take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer on the four Cluster spacecraft. The calibrated observations of the three spectrometers are used to determine the proton and electron velocity moments. The velocity moments can be used to estimate the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. As the measurement techniques are so different, it is quite plausible that when two different measurements yield the same DC electric field, it is the correct field. All five measurements of the DC electric field are usually not simultaneously available, especially on Cluster 2 where CODIF and HIA are not operational, or on Cluster 4 where EDI is off. In this presentation we investigate DC electric field in various transient plasma sheet events such as dipolarization events and BBF's and how the five measurements agree or disagree. There are plenty of important issues that are considered, e.g., (1) what kind of DC electric fields exist in such events and what are their spatial scales, (2) do electrons and ions perform ExB drift motions in these events, and (3) how well the instruments have been calibrated.

Thermoelectric Properties of Novel One-dimensional and Two-dimensional Systems Based on MoS2 Nanoribbons and Sheets

NASA Astrophysics Data System (ADS)

Arab, Abbas

Atomically thin materials such as hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMDCs) have attracted a lot of interest since the discovery of Graphene. Potential use of Graphene in semiconductor industry has been hindered by the fact that graphene is a semi metal with zero band gap. The difficulties in engineering band gap in graphene turn the focus light to inherent semiconducting two-dimensional (2D) materials; TMDCs. Bulk of TMDCs are formed by layers vertically stacked and weakly bonded together via weak van der Waals interactions. These weak interlayer forces make it possible to obtain monolayer by using scotch tape exfoliation or lithium-ion intercalation. Among the semiconducting members of TMDCs, MoS 2 is the most appealing candidate, partly due to its thermal stability and also for its natural abundance. Intensive study of electronic properties of MoS2 has revealed the desirable band gap (1.2 eV), good carrier xmobility (which is close to those of silicon thin films and graphene nanoribbons), thermal stability and a surface free from dangling bonds make it a perfect candidate for electronic and opto-electronic applications. Despite the fact that MoS2 has a high Seebeck coefficient, its thermoelectric properties have not studied as well as it should be. In this work, we have studied thermoelectric properties of monolayer and fewlayer MoS2 sheets in both armchair and zigzag orientations and also of monolayer MoS2 armchair nanoribbons. Density functional theory (DFT) using non-equilibrium Green's function (NEGF) method in ballistic transport regime of Landauer-Buttiker formulation in linear transport approximation has been implemented to calculate the transmission spectra and consequently electronic transport coefficients. Phonon transmission spectra are calculated based on parameterization of Stillinger-Weber potential. Thermoelectric figure of merit, ZT, is calculated using these electronic and phonon transmission spectra. In the case of MoS2 sheets, thermoelectric properties of monolayer, bilayer, trilayer and quadlayer in armchair and zigzag directions have been studied. Our results show that as number of layers increase from monolayer to quadlayer, both transmission spectrum and phonon thermal conductance increase. In addition, strong electronic and thermal anisotropy is found between zigzag and armchair orientations. Transmission coefficient and phonon thermal conductance of zigzag orientation is higher than those of armchair with the same number of layers. Electrical conductance and phonon thermal conductance are competing forces in achieving a high thermoelectric figure of merit. Advantage of having a higher electrical conductance in zigzag orientation has been nullified by having a higher phonon thermal conductance. In fact, our results show higher thermoelectric xifigure of merit for armchair oriented than zigzag oriented sheets. Also as number of layer decreases from quadlayer to monolayer, we are witnessing a higher thermoelectric figure of merit for both armchair and zigzag oriented sheets. Hence, the highest achieved thermoelectric figure of merit was obtained by monolayer armchair MoS2 sheet for both p-type and n-type semiconducting behavior. In case of MoS2 armchair nanoribbons, effect of several factors has been studied; width of nanoribbon, Sulfur vacancy and edge roughness. The electronic properties of nanoribbons are dominated by the presence of edge states that are dependent on the number of zigzag chains across the nanoribbon. In addition, it is found that the phonon thermal conductance of monolayer MoS2 armchair nanoribbon is smaller compared to MoS2 monolayer armchair sheet. This outcome can be explained by phonon edge scattering. The effect of this phonon edge scattering is more pronounced in narrower nanoribbons compared to wide ones which leads to higher thermoelectric figure of merit for narrow nanoribbons. The effect of edge roughness and sulfur vacancy on thermoelectric behavior of MoS2 nanoribbons is also studied. Our result shows that edge roughness decreased the thermoelectric figure of merit compared to those of a perfect nanoribbon as its impact on electrical conductance is more severe than on phonon thermal conductance. Sulfur vacancy, however, improved thermoelectric figure of merit of MoS2 nanoribbons. It has been shown that thermoelectric figure of merit as high as 4 and 3 at T = 500K can be achieved n-doped and p-doped MoS2 nanoribbons. The ability of getting a high thermoelectric figure of merit for both n-type and p-type behavior from the same material will be a huge boost to thermoelectric industry if realized.

A current disruption mechanism in the neutral sheet - A possible trigger for substorm expansions

NASA Technical Reports Server (NTRS)

Lui, A. T. Y.; Mankofsky, A.; Chang, C.-L.; Papadopoulos, K.; Wu, C. S.

1990-01-01

A linear analysis is performed to investigate the kinetic cross-field streaming instability in the earth's magnetotail neutral sheet region. Numerical solution of the dispersion equation shows that the instability can occur under conditions expected for the neutral sheet just prior to the onset of substorm expansion. The excited waves are obliquely propagating whistlers with a mixed polarization in the lower hybrid frequency range. The ensuing turbulence of this instability can lead to a local reduction of the cross-tail current causing it to continue through the ionosphere to form a substorm current wedge. A substorm expansion onset scenario is proposed based on this instability in which the relative drift between ions and electrons is primarily due to unmagnetized ions undergoing current sheet acceleration in the presence of a cross-tail electric field. The required electric field strength is within the range of electric field values detected in the neutral sheet region during substorm intervals. The skew in local time of substorm onset location and the three conditions under which substorm onset is observed can be understood on the basis of the proposed scenario.

The use of cell-sheet technique eliminates arrhythmogenicity of skeletal myoblast-based therapy to the heart with enhanced therapeutic effects.

PubMed

Narita, Takuya; Shintani, Yasunori; Ikebe, Chiho; Kaneko, Masahiro; Harada, Narumi; Tshuma, Nomathamsanqa; Takahashi, Kunihiko; Campbell, Niall G; Coppen, Steven R; Yashiro, Kenta; Sawa, Yoshiki; Suzuki, Ken

2013-09-20

Clinical application of skeletal myoblast transplantation has been curtailed due to arrhythmogenicity and inconsistent therapeutic benefits observed in previous studies. However, these issues may be solved by the use of a new cell-delivery mode. It is now possible to generate "cell-sheets" using temperature-responsive dishes without artificial scaffolds. This study aimed to validate the safety and efficacy of epicardial placement of myoblast-sheets (myoblast-sheet therapy) in treating heart failure. After coronary artery ligation in rats, the same numbers of syngeneic myoblasts were transplanted by intramyocardial injection or cell-sheet placement. Continuous radio-telemetry monitoring detected increased ventricular arrhythmias, including ventricular tachycardia, after intramyocardial injection compared to the sham-control, while these were abolished in myoblast-sheet therapy. This effect was conjunct with avoidance of islet-like cell-cluster formation that disrupts electrical conduction, and with prevention of increased arrhythmogenic substrates due to exaggerated inflammation. Persistent ectopic donor cells were found in the lung only after intramyocardial injection, strengthening the improved safety of myoblast-sheet therapy. In addition, myoblast-sheet therapy enhanced cardiac function, corresponding to a 9.2-fold increase in donor cell survival, compared to intramyocardial injection. Both methods achieved reduced infarct size, decreased fibrosis, attenuated cardiomyocyte hypertrophy, and increased neovascular formation, in association with myocardial upregulation of a group of relevant molecules. The pattern of these beneficial changes was similar between two methods, but the degree was more substantial after myoblast-sheet therapy. The cell-sheet technique enhanced safety and therapeutic efficacy of myoblast-based therapy, compared to the current method, thereby paving the way for clinical application. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Efficient and large scale synthesis of graphene from coal and its film electrical properties studies.

PubMed

Wu, Yingpeng; Ma, Yanfeng; Wang, Yan; Huang, Lu; Li, Na; Zhang, Tengfei; Zhang, Yi; Wan, Xiangjian; Huang, Yi; Chen, Yongsheng

2013-02-01

Coal, which is abundant and has an incompact structure, is a good candidate to replace graphite as the raw material for the production of graphene. Here, a new solution phase technique for the preparation of graphene from coal has been developed. The precursor: graphene oxide got from coal was examined by atomic force microscopy, dynamic light scattering and X-ray diffraction, the results showed the GO was a small and single layer sheet. The graphene was examined by X-ray photoelectron spectroscopy, and Raman spectroscopy. Furthermore, graphene films have been prepared using direct solution process and the electrical conductivity and Hall effect have been studied. The results showed the conductivity of the films could reach as high as 2.5 x 10(5) Sm(-1) and exhibited an n-type behavior.

Continious production of exfoliated graphite composite compositions and flow field plates

DOEpatents

Shi, Jinjun; Zhamu, Aruna; Jang, Bor Z.

2010-07-20

A process of continuously producing a more isotropic, electrically conductive composite composition is provided. The process comprises: (a) continuously supplying a compressible mixture comprising exfoliated graphite worms and a binder or matrix material, wherein the binder or matrix material is in an amount of between 3% and 60% by weight based on the total weight of the mixture; (b) continuously compressing the compressible mixture at a pressure within the range of from about 5 psi or 0.035 MPa to about 50,000 psi or 350 MPa in at least a first direction into a cohered graphite composite compact; and (c) continuously compressing the composite compact in a second direction, different from the first direction, to form the composite composition in a sheet or plate form. The process leads to composite plates with exceptionally high thickness-direction electrical conductivity.

Conducting tin halides with a layered organic-based perovskite structure

NASA Astrophysics Data System (ADS)

Mitzi, D. B.; Feild, C. A.; Harrison, W. T. A.; Guloy, A. M.

1994-06-01

THE discovery1 of high-temperature superconductivity in layered copper oxide perovskites has generated considerable fundamental and technological interest in this class of materials. Only a few other examples of conducting layered perovskites are known; these are also oxides such as (La1-xSrx)n+1 MnnO3n+1 (ref. 2), Lan+1NinO3n+1 (ref. 3) and Ban+1PbnO3n+1 (ref. 4), all of which exhibit a trend from semiconducting to metallic behaviour with increasing number of perovskite layers (n). We report here the synthesis of a family of organic-based layered halide perovskites, (C4H9NH3)2(CH3NH3)n-1Snnl3n+1 which show a similar transition from semiconducting to metallic behaviour with increasing n. The incorporation of an organic modulation layer between the conducting tin iodide sheets potentially provides greater flexibility for tuning the electrical properties of the perovskite sheets, and we suggest that such an approach will prove valuable for exploring the range of transport properties possible with layered perovskites.

Solution-Processable transparent conducting electrodes via the self-assembly of silver nanowires for organic photovoltaic devices.

PubMed

Tugba Camic, B; Jeong Shin, Hee; Hasan Aslan, M; Basarir, Fevzihan; Choi, Hyosung

2018-02-15

Solution-processed transparent conducting electrodes (TCEs) were fabricated via the self-assembly deposition of silver nanowires (Ag NWs). Glass substrates modified with (3-aminopropyl)triethoxysilane (APTES) and (3-mercaptopropyl)trimethoxysilane (MPTES) were coated with Ag NWs for various deposition times, leading to three different Ag NWs samples (APTES-Ag NWs (PVP), MPTES-Ag NWs (PVP), and APTES-Ag NWs (COOH)). Controlling the deposition time produced Ag NWs monolayer thin films with different optical transmittance and sheet resistance. Post-annealing treatment improved their electrical conductivity. The Ag NWs films were successfully characterized using UV-Vis spectroscopy, field emission scanning electron microscopy, optical microscopy and four-point probe. Three Ag NWs films exhibited low sheet resistance of 4-19Ω/sq and high optical transmittance of 65-81% (at 550nm), which are comparable to those of commercial ITO electrode. We fabricated an organic photovoltaic device by using Ag NWs as the anode instead of ITO electrode, and optimized device with Ag NWs exhibited power conversion efficiency of 1.72%. Copyright © 2017 Elsevier Inc. All rights reserved.

Properties of large electric fields in the plasma sheet at 4-7RE measured with Polar

NASA Astrophysics Data System (ADS)

Keiling, A.; Wygant, J. R.; Cattell, C.; Johnson, M.; Temerin, M.; Mozer, F. S.; Kletzing, C. A.; Scudder, J.; Russell, C. T.

2001-04-01

Measurements from the Polar satellite provide evidence for large electric field structures in the plasma sheet at geocentric distances of 4-7RE. These structures had amplitudes perpendicular to the ambient magnetic field that can exceed 100 mV m-1 (6 s averaged). Two years (from May 1, 1996, to April 30, 1998) of electric field data (EZ component, approximately along GSE z) were surveyed. The distribution in invariant latitude (ILAT) and magnetic local time (MLT) of large perpendicular electric field events (defined as >=20 mV m-1 for a 6-s average) delineates the statistical auroral oval with the majority of events occurring in the nightside centered around midnight and a smaller concentration around 1500 MLT. The magnitude-versus-altitude distribution of the electric fields between 4 and 7RE in the nightside could be explained by models which assume either shear Alfvén waves propagating into regions of larger background magnetic fields or electrostatic structures being mapped quasi-statically along equipotential magnetic field lines. In addition, this survey yielded 24 very large amplitude events with |E⊥|>=100mVm-1 (6 s averaged), all of which occurred in the nightside. In the spacecraft frame, the electric field structures occurred on timescales ranging from 10 to 60 s. About 85% of these events occurred in the vicinity of the outer boundary of the plasma sheet; the rest occurred in the central plasma sheet. The polarity of the electric fields was dominantly perpendicular to the nominal plasma sheet boundary. For a large fraction of events (<=50%) the ratios of electric and magnetic fields in the period range from 10 to 60 s were consistent with Alfvén waves. Large Poynting flux (up to 2.5 ergs cm-2s-1) dominantly directed downward along the background magnetic field was associated with 21 events. All 24 events occurred during geomagnetic disturbances such as magnetic substorms. A conjugate study with ground stations for 14 events (out of the 24 events) showed that these structures occurred during times of rapid changes in the H component (or X component) of magnetometer data. For most events this time corresponded to the expansion phase; two events occurred during a quick recovery of the negative H bay signature. Thus there is evidence that large electromagnetic energy transfer processes in the plasma sheet occur during the most dynamic phase of geomagnetic disturbances. From the statistical analysis it was found that Polar observed events larger than 100 mV m-1 (50 mV m-1) in the plasma sheet between 2100 and 0300 MLT with a 2-4% (15%) probability per crossing. These probabilities will be compared to the probability of substorm occurrence during Polar plasma sheet crossings.

The mechanistic exploration of porous activated graphene sheets-anchored SnO2 nanocrystals for application in high-performance Li-ion battery anodes.

PubMed

Yang, Yingchang; Ji, Xiaobo; Lu, Fang; Chen, Qiyuan; Banks, Craig E

2013-09-28

Porous activated graphene sheets have been for the first time exploited herein as encapsulating substrates for lithium ion battery (LIB) anodes. The as-fabricated SnO2 nanocrystals-porous activated graphene sheet (AGS) composite electrode exhibits improved electrochemical performance as an anode material for LIBs, such as better cycle performance and higher rate capability in comparison with graphene sheets, activated graphene sheets, bare SnO2 and SnO2-graphene sheet composites. The superior electrochemical performances of the designed anode can be ascribed to the porous AGS substrate, which improves the electrical conductivity of the electrode, inhibits agglomeration between particles and effectively buffers the strain from the volume variation during Li(+)-intercalation-de-intercalation and provides more cross-plane diffusion channels for Li(+) ions. As a result, the designed anode exhibits an outstanding capacity of up to 610 mA h g(-1) at a current density of 100 mA g(-1) after 50 cycles and a good rate performance of 889, 747, 607, 482 and 372 mA h g(-1) at a current density of 100, 200, 500, 1000, and 2000 mA g(-1), respectively. This work is of importance for energy storage as it provides a new substrate for the design and implementation of next-generation LIBs exhibiting exceptional electrochemical performances.

Thermal and Electrical Characterization of Alumina Substrate for Microelectronic Applications

NASA Astrophysics Data System (ADS)

Ahmad, S.; Ibrahim, A.; Alias, R.; Shapee, S. M.; Ambak, Z.; Zakaria, S. Z.; Yahya, M. R.; Mat, A. F. A.

2010-03-01

This paper reports the effect of sintering temperature on thermal and electrical properties of alumina material as substrate for microelectronic devices. Alumina materials in the form of green sheet with 1 mm thickness were sintered at 1100° C, 1300° C and 1500° C for about 20 hours using heating and cooling rates of 2° C/min. The densities were measured using densitometer and the microstructures of the samples were analyzed using SEM micrographs. Meanwhile thermal and electrical properties of the samples were measured using flash method and impedance analyzer respectively. It was found that thermal conductivity and thermal diffusivity of the substrate increases as sintering temperature increases. It was found also that the dielectric constant of alumina substrate increases as the sintering temperature increases.

Conducting polymer composite film incorporated with aligned carbon nanotubes for transparent, flexible and efficient supercapacitor

PubMed Central

Lin, Huijuan; Li, Li; Ren, Jing; Cai, Zhenbo; Qiu, Longbin; Yang, Zhibin; Peng, Huisheng

2013-01-01

Polyaniline composite films incorporated with aligned multi-walled carbon nanotubes (MWCNTs) are synthesized through an easy electrodeposition process. These robust and electrically conductive films are found to function as effective electrodes to fabricate transparent and flexible supercapacitors with a maximum specific capacitance of 233 F/g at a current density of 1 A/g. It is 36 times of bare MWCNT sheet, 23 times of pure polyaniline and 3 times of randomly dispersed MWCNT/polyaniline film under the same conditions. The novel supercapacitors also show a high cyclic stability. PMID:23443325

Interior view of the Sheet Metal Shop showing the roof ...

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

Interior view of the Sheet Metal Shop showing the roof trusses and corrugated metal roof covering, view facing northwest - Kahului Cannery, Plant No. 28, Boiler House, Sheet Metal and Electrical Shops, 120 Kane Street, Kahului, Maui County, HI

Metal rubber sensor technology to enable in-flight icing measurement

NASA Astrophysics Data System (ADS)

Berg, Michelle; Lalli, Jennifer; Claus, Richard; Kreeger, Richard E.

2017-04-01

This paper describes the development and testing of Metal Rubber sensors for the nondestructive, normal force detection of ice accretion on aerospace structures. The buildup of ice on aircraft engine components, wings and rotorblades is a problem for both civilian and military aircraft that must operate under all weather conditions. Ice adds mass to moving components, thus changing the equations of motion that control the operation of the system as well as increasing drag and torque requirements. Ice also alters the surface geometry of leading edges, altering the airflow transition from laminar to turbulent, generating turbulence and again increasing drag. Metal Rubber is a piezoresistive material that exhibits a change in electrical resistance in response to physical deformation. It is produced as a freestanding sheet that is assembled at the molecular level using alternating layers of conductive metal nanoparticles and polymers. As the volume percentage of the conductive nanoparticle clusters within the material is increased from zero, the onset of electrical conduction occurs abruptly at the percolation threshold. Electrical conduction occurs due to electron hopping between the clusters. If a length of the material is strained, the clusters move apart so the efficiency of electron hopping decreases and electrical resistance increases. The resulting change in resistance as a function of the change in strain in the material, at a specific volume percentage of conductive clusters, can be interpreted as the transduction response of the material. We describe how sensors fabricated from these materials can be used to measure ice buildup.

Plasma-electric field controlled growth of oriented graphene for energy storage applications

NASA Astrophysics Data System (ADS)

Ghosh, Subrata; Polaki, S. R.; Kamruddin, M.; Jeong, Sang Mun; (Ken Ostrikov, Kostya

2018-04-01

It is well known that graphene grows as flat sheets aligned with the growth substrate. Oriented graphene structures typically normal to the substrate have recently attracted major attention. Most often, the normal orientation is achieved in a plasma-assisted growth and is believed to be due to the plasma-induced in-built electric field, which is usually oriented normal to the substrate. This work focuses on the effect of an in-built electric field on the growth direction, morphology, interconnectedness, structural properties and also the supercapacitor performance of various configurations of graphene structures and reveals the unique dependence of these features on the electric field orientation. It is shown that tilting of growth substrates from parallel to the normal direction with respect to the direction of in-built plasma electric field leads to the morphological transitions from horizontal graphene layers, to oriented individual graphene sheets and then interconnected 3D networks of oriented graphene sheets. The revealed transition of the growth orientation leads to a change in structural properties, wetting nature, types of defect in graphitic structures and also affects their charge storage capacity when used as supercapacitor electrodes. This simple and versatile approach opens new opportunities for the production of potentially large batches of differently oriented and structured graphene sheets in one production run.

Bridging Redox Species-Coated Graphene Oxide Sheets to Electrode for Extending Battery Life Using Nanocomposite Electrolyte.

PubMed

Huang, Yi Fu; Ruan, Wen Hong; Lin, Dong Ling; Zhang, Ming Qiu

2017-01-11

Substituting conventional electrolyte for redox electrolyte has provided a new intriguing method for extending battery life. The efficiency of utilizing the contained redox species (RS) in the redox electrolyte can benefit from increasing the specific surface area of battery electrodes from the electrode side of the electrode-electrolyte interface, but is not limited to that. Herein, a new strategy using nanocomposite electrolyte is proposed to enlarge the interface with the aid of nanoinclusions from the electrolyte side. To do this, graphene oxide (GO) sheets are first dispersed in the electrolyte solution of tungstosilicic salt/lithium sulfate/poly(vinyl alcohol) (SiWLi/Li 2 SO 4 /PVA), and then the sheets are bridged to electrode, after casting and evaporating the solution on the electrode surface. By applying in situ conductive atomic force microscopy and Raman spectra, it is confirmed that the GO sheets doped with RS of SiWLi/Li 2 SO 4 can be bridged and electrically reduced as an extended electrode-electrolyte interface. As a result, the RS-coated GO sheets bridged to LiTi 2 (PO 4 ) 3 //LiMn 2 O 4 battery electrodes are found to deliver extra energy capacity (∼30 mAh/g) with excellent electrochemical cycling stability, which successfully extends the battery life by over 50%.

Large-scale flows, sheet plumes and strong magnetic fields in a rapidly rotating spherical dynamo

NASA Astrophysics Data System (ADS)

Takahashi, F.

2011-12-01

Mechanisms of magnetic field intensification by flows of an electrically conducting fluid in a rapidly rotating spherical shell is investigated. Bearing dynamos of the Eartn and planets in mind, the Ekman number is set at 10-5. A strong dipolar solution with magnetic energy 55 times larger than the kinetic energy of thermal convection is obtained. In a regime of small viscosity and inertia with the strong magnetic field, convection structure consists of a few large-scale retrograde flows in the azimuthal direction and sporadic thin sheet-like plumes. The magnetic field is amplified through stretching of magnetic lines, which occurs typically through three types of flow: the retrograde azimuthal flow near the outer boundary, the downwelling flow of the sheet plume, and the prograde azimuthal flow near the rim of the tangent cylinder induced by the downwelling flow. It is found that either structure of current loops or current sheets is accompanied in each flow structure. Current loops emerge as a result of stretching the magnetic lines along the magnetic field, wheres the current sheets are formed to counterbalance the Coriolis force. Convection structure and processes of magnetic field generation found in the present model are distinct from those in models at larger/smaller Ekman number.

Fine scale structure in the current sheet and electrostatic fields during driven magnetic reconnection on the VTF experiment.

NASA Astrophysics Data System (ADS)

Fox, William

2005-10-01

We have conducted a series of experiments in the VTF reconnection experiment[1] to measure with high resolution the current channel and electric structures that form in response to driven reconnection. Preliminary measurements have revealed that the current sheet is not symmetric across the X-line, contradicting an assumption fundamental to nearly every reconnection theory. Importantly, effects related to this asymmetry can account for momentum balance for the electrons at the X-line (i.e. fulfillment of the generalized Ohm's law) via convective inertia (m n v.∇v||). Measurements of strong in-plane electric field structures (E˜ 1 kV/m) near the X-point reveal a mechanism to efficiently heat ions, as has been recently observed by laser induced fluorescence (LIF) measurements of the ion distribution function[2].This work was supported by a DoE Fusion Energy Sciences Fellowship.[1] J. Egedal, et. al. (2001), Rev. Sci. Instrum. 71, 3351 [2] A. Stark, W. Fox, J.Egedal, O. Grulke, T. Klinger, (2005), submitted to Phys. Rev. Lett.

Multilayer capacitor suitable for substrate integration and multimegahertz filtering

DOEpatents

Ngo, Khai D. T.

1990-01-01

A multilayer capacitor comprises stacked, spaced-apart electrodes of sheet form, dielectric layers between the electrodes, and first and second groups of spaced-apart conductive vias extending transversely of the sheet-form electrodes and through aligned holes in the dielectric layers. Alternate electrodes are instantaneously positive, and the remaining electrodes are instantaneously negative. Each via of the first group is electrically connected to the positive electrodes and passes insulatingly through the negative electrodes. Similarly, each via of the second group is electrically connected to the negative electrodes and passes insulatingly through the positive electrodes. Each via has, in the plane of the electrodes, a cross-sectional form in the shape of an elongated rib of greater length than width. The elongated ribs of the first group are disposed in a first plurality of rows with their lengths in spaced-apart, aligned relationship, and the ribs of the second group are disposed in a second plurality of rows with their lengths in spaced-apart, aligned relationship. The first plurality of rows is disposed substantially orthogonally with respect to the second plurality of rows.

Direct observation of spatially heterogeneous single-layer graphene oxide reduction kinetics.

PubMed

McDonald, Matthew P; Eltom, Ahmed; Vietmeyer, Felix; Thapa, Janak; Morozov, Yurii V; Sokolov, Denis A; Hodak, Jose H; Vinodgopal, Kizhanipuram; Kamat, Prashant V; Kuno, Masaru

2013-01-01

Graphene oxide (GO) is an important precursor in the production of chemically derived graphene. During reduction, GO's electrical conductivity and band gap change gradually. Doping and chemical functionalization are also possible, illustrating GO's immense potential in creating functional devices through control of its local hybridization. Here we show that laser-induced photolysis controllably reduces individual single-layer GO sheets. The reaction can be followed in real time through sizable decreases in GO's photoluminescence efficiency along with spectral blueshifts. As-produced reduced graphene oxide (rGO) sheets undergo additional photolysis, characterized by dramatic emission enhancements and spectral redshifts. Both GO's reduction and subsequent conversion to photobrightened rGO are captured through movies of their photoluminescence kinetics. Rate maps illustrate sizable spatial and temporal heterogeneities in sp(2) domain growth and reveal how reduction "flows" across GO and rGO sheets. The observed heterogeneous reduction kinetics provides mechanistic insight into GO's conversion to chemically derived graphene and highlights opportunities for overcoming its dynamic, chemical disorder.

Recompressed exfoliated graphite articles

DOEpatents

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

2013-08-06

This invention provides an electrically conductive, less anisotropic, recompressed exfoliated graphite article comprising a mixture of (a) expanded or exfoliated graphite flakes; and (b) particles of non-expandable graphite or carbon, wherein the non-expandable graphite or carbon particles are in the amount of between about 3% and about 70% by weight based on the total weight of the particles and the expanded graphite flakes combined; wherein the mixture is compressed to form the article having an apparent bulk density of from about 0.1 g/cm.sup.3 to about 2.0 g/cm.sup.3. The article exhibits a thickness-direction conductivity typically greater than 50 S/cm, more typically greater than 100 S/cm, and most typically greater than 200 S/cm. The article, when used in a thin foil or sheet form, can be a useful component in a sheet molding compound plate used as a fuel cell separator or flow field plate. The article may also be used as a current collector for a battery, supercapacitor, or any other electrochemical cell.

Surface Structure Dependent Electrocatalytic Activity of Co3O4 Anchored on Graphene Sheets toward Oxygen Reduction Reaction

PubMed Central

Xiao, Junwu; Kuang, Qin; Yang, Shihe; Xiao, Fei; Wang, Shuai; Guo, Lin

2013-01-01

Catalytic activity is primarily a surface phenomenon, however, little is known about Co3O4 nanocrystals in terms of the relationship between the oxygen reduction reaction (ORR) catalytic activity and surface structure, especially when dispersed on a highly conducting support to improve the electrical conductivity and so to enhance the catalytic activity. Herein, we report a controllable synthesis of Co3O4 nanorods (NR), nanocubes (NC) and nano-octahedrons (OC) with the different exposed nanocrystalline surfaces ({110}, {100}, and {111}), uniformly anchored on graphene sheets, which has allowed us to investigate the effects of the surface structure on the ORR activity. Results show that the catalytically active sites for ORR should be the surface Co2+ ions, whereas the surface Co3+ ions catalyze CO oxidation, and the catalytic ability is closely related to the density of the catalytically active sites. These results underscore the importance of morphological control in the design of highly efficient ORR catalysts. PMID:23892418

Numerical study of MHD nanofluid flow and heat transfer past a bidirectional exponentially stretching sheet

NASA Astrophysics Data System (ADS)

Ahmad, Rida; Mustafa, M.; Hayat, T.; Alsaedi, A.

2016-06-01

Recent advancements in nanotechnology have led to the discovery of new generation coolants known as nanofluids. Nanofluids possess novel and unique characteristics which are fruitful in numerous cooling applications. Current work is undertaken to address the heat transfer in MHD three-dimensional flow of magnetic nanofluid (ferrofluid) over a bidirectional exponentially stretching sheet. The base fluid is considered as water which consists of magnetite-Fe3O4 nanoparticles. Exponentially varying surface temperature distribution is accounted. Problem formulation is presented through the Maxwell models for effective electrical conductivity and effective thermal conductivity of nanofluid. Similarity transformations give rise to a coupled non-linear differential system which is solved numerically. Appreciable growth in the convective heat transfer coefficient is observed when nanoparticle volume fraction is augmented. Temperature exponent parameter serves to enhance the heat transfer from the surface. Moreover the skin friction coefficient is directly proportional to both magnetic field strength and nanoparticle volume fraction.

Commercial scale production of Fe-6.5 wt. % Si sheet and its magnetic properties

NASA Astrophysics Data System (ADS)

Takada, Y.; Abe, M.; Masuda, S.; Inagaki, J.

1988-11-01

Commercial scale production of a Fe-6.5 wt. % Si sheet has been successfully developed. Presently manufactured sheets are in coil form, whose thickness ranges from 0.1 to 0.5 mm with a maximum width of 400 mm. Magnetic properties of the manufactured sheet have been investigated. The permeability of Fe-6.5 wt. % Si sheet is about 10 times higher than the conventional nonoriented silicon steel sheet. The core losses are less than half the conventional, and even less than that of the grain-oriented silicon steel sheet at frequencies over 400 Hz. Superior soft magnetic properties are attributed to the low magnetostriction and high electric resistivity of this alloy. It is well known that the Fe-6.5 wt. % Si alloy has poor ductility in conventional mechanical work. But investigation of the forming conditions has enabled the stamping and bending of alloy sheets. Low core losses and high permeability make Fe-6.5 wt. % Si sheet adequate for motor cores, transformer cores operating at high frequencies, and magnetic shielding. Application to the micromotor core shows that Fe-6.5 wt. % Si sheet reduces the consumption of no-load electric current by 25% in comparison with the conventional silicon steel.

Effect of high-latitude ionospheric convection on Sun-aligned polar caps

NASA Technical Reports Server (NTRS)

Sojka, J. J.; Zhu, L.; Crain, D. J.; Schunk, R. W.

1994-01-01

A coupled magnetospheric-ionospheric (M-I) magnetohydrodynamic (MHD) model has been used to simulate the formation of Sun-aligned polar cap arcs for a variety of interplanetary magnetic field (IMF) dependent polar cap convection fields. The formation process involves launching an Alfven shear wave from the magnetosphere to the ionosphere where the ionospheric conductance can react self-consistently to changes in the upward currents. We assume that the initial Alfven shear wave is the result of solar wind-magnetosphere interactions. The simulations show how the E region density is affected by the changes in the electron precipitation that are associated with the upward currents. These changes in conductance lead to both a modified Alfven wave reflection at the ionosphere and the generation of secondary Alfven waves in the ionosphere. The ensuing bouncing of the Alfven waves between the ionosphere and magnetosphere is followed until an asymptotic solution is obtained. At the magnetosphere the Alfven waves reflect at a fixed boundary. The coupled M-I Sun-aligned polar cap arc model of Zhu et al.(1993a) is used to carry out the simulations. This study focuses on the dependence of the polar cap arc formation on the background (global) convection pattern. Since the polar cap arcs occur for northward and strong B(sub y) IMF conditions, a variety of background convection patterns can exist when the arcs are present. The study shows that polar cap arcs can be formed for all these convection patterns; however, the arc features are dramatically different for the different patterns. For weak sunward convection a relatively confined single pair of current sheets is associated with the imposed Alfven shear wave structure. However, when the electric field exceeds a threshold, the arc structure intensifies, and the conductance increases as does the local Joule heating rate. These increases are faster than a linear dependence on the background electric field strength. Furthermore, above the threshold, the single current sheet pair splits into multiple current sheet pairs. For the fixed initial ionospheric and magnetospheric conditions used in this study, the separation distance between the current pairs was found to be almost independent of the background electric field strength. For either three-cell or distorted two-cell background convection patterns the arc formation favored the positive B(sub y) case in the northern hemisphere.

Graphene—vertically aligned carbon nanotube hybrid on PDMS as stretchable electrodes

NASA Astrophysics Data System (ADS)

Ding, Junjun; Fu, Shichen; Zhang, Runzhi; Boon, Eric; Lee, Woo; Fisher, Frank T.; Yang, Eui-Hyeok

2017-11-01

Stretchable electrodes are a critical component for flexible electronics such as displays, energy devices, and wearable sensors. Carbon nanotubes (CNTs) and graphene have been considered for flexible electrode applications, due to their mechanical strength, high carrier mobility, and excellent thermal conductivity. Vertically aligned carbon nanotubes (VACNTs) provide the possibility to serve as interconnects to graphene sheets as stretchable electrodes that could maintain high electrical conductivity under large tensile strain. In this work, a graphene oxide (GO)-VACNT hybrid on a PDMS substrate was demonstrated. Here, 50 μm long VACNTs were grown on a Si/SiO2 wafer substrate via atmospheric pressure chemical vapor deposition. VACNTs were directly transferred by delamination from the Si/SiO2 to a semi-cured PDMS substrate, ensuring strong adhesion between VACNTs and PDMS upon full curing of the PDMS. GO ink was then printed on the surface of the VACNT carpet and thermally reduced to reduced graphene oxide (rGO). The sheet resistance of the rGO-VACNT hybrid was measured under uniaxial tensile strains up to 300% applied to the substrate. Under applied strain, the rGO-VACNT hybrid maintained a sheet resistant of 386 ± 55 Ω/sq. Cyclic stretching of the rGO-VACNT hybrid was performed with up to 50 cycles at 100% maximum tensile strain, showing no increase in sheet resistance. These results demonstrate promising performance of the rGO-VACNT hybrid for flexible electronics applications.

Graphene-Vertically Aligned Carbon Nanotube Hybrid on PDMS as Stretchable Electrodes.

PubMed

Ding, Junjun; Fu, Shichen; Zhang, Runzhi; Boon, Eric Peter; Lee, Woo; Fisher, Frank T; Yang, Eui-Hyeok

2017-09-11

Stretchable electrodes are a critical component for flexible electronics such as displays, energy devices, and wearable sensors. Carbon nanotubes (CNTs) and graphene have been considered for flexible electrode applications, due to their mechanical strength, high carrier mobility, and excellent thermal conductivity. Vertically aligned carbon nanotubes (VACNTs) provide the possibility to serve as interconnects to graphene sheets as stretchable electrodes that could maintain high electrical conductivity under large tensile strain. In this work, a graphene oxide (GO) -VACNT hybrid on a PDMS substrate was demonstrated. Here, 50 μm long VACNTs were grown on a Si/SiO2 wafer substrate via atmospheric pressure chemical vapor deposition (APCVD). VACNTs were directly transferred by delamination from the Si/SiO2 to a semi-cured PDMS substrate, ensuring strong adhesion between VACNTs and PDMS upon full curing of the PDMS. GO ink was then printed on the surface of the VACNT carpet and thermally reduced to reduced graphene oxide (rGO). The sheet resistance of the rGO-VACNT hybrid was measured under uniaxial tensile strains up to 300% applied to the substrate. Under applied strain, the rGO-VACNT hybrid maintained a sheet resistant of 386±55 Ω/sq. Cyclic stretching of the rGO-VACNT hybrid was performed with up to 50 cycles at 100% maximum tensile strain, showing no increase in sheet resistance. These results demonstrate promising performance of the rGO-VACNT hybrid for flexible electronics applications. © 2017 IOP Publishing Ltd.

A lightweight scalable agarose-gel-synthesized thermoelectric composite

NASA Astrophysics Data System (ADS)

Kim, Jin Ho; Fernandes, Gustavo E.; Lee, Do-Joong; Hirst, Elizabeth S.; Osgood, Richard M., III; Xu, Jimmy

2018-03-01

Electronic devices are now advancing beyond classical, rigid systems and moving into lighweight flexible regimes, enabling new applications such as body-wearables and ‘e-textiles’. To support this new electronic platform, composite materials that are highly conductive yet scalable, flexible, and wearable are needed. Materials with high electrical conductivity often have poor thermoelectric properties because their thermal transport is made greater by the same factors as their electronic conductivity. We demonstrate, in proof-of-principle experiments, that a novel binary composite can disrupt thermal (phononic) transport, while maintaining high electrical conductivity, thus yielding promising thermoelectric properties. Highly conductive Multi-Wall Carbon Nanotube (MWCNT) composites are combined with a low-band gap semiconductor, PbS. The work functions of the two materials are closely matched, minimizing the electrical contact resistance within the composite. Disparities in the speed of sound in MWCNTs and PbS help to inhibit phonon propagation, and boundary layer scattering at interfaces between these two materials lead to large Seebeck coefficient (> 150 μV/K) (Mott N F and Davis E A 1971 Electronic Processes in Non-crystalline Materials (Oxford: Clarendon), p 47) and a power factor as high as 10 μW/(K2 m). The overall fabrication process is not only scalable but also conformal and compatible with large-area flexible hosts including metal sheets, films, coatings, possibly arrays of fibers, textiles and fabrics. We explain the behavior of this novel thermoelectric material platform in terms of differing length scales for electrical conductivity and phononic heat transfer, and explore new material configurations for potentially lightweight and flexible thermoelectric devices that could be networked in a textile.

Highly efficient flexible optoelectronic devices using metal nanowire-conducting polymer composite transparent electrode

NASA Astrophysics Data System (ADS)

Jung, Eui Dae; Nam, Yun Seok; Seo, Houn; Lee, Bo Ram; Yu, Jae Choul; Lee, Sang Yun; Kim, Ju-Young; Park, Jang-Ung; Song, Myoung Hoon

2015-09-01

Here, we report a comprehensive analysis of the electrical, optical, mechanical, and surface morphological properties of composite nanostrutures based on silver nanowires (AgNW) and PEDOT:PSS conducting polymer for the use as flexible and transparent electrodes. Compared to ITO or the single material of AgNW or PEDOT:PSS, the AgNW/PEDOT:PSS composite electrode showed high electrical conductivity with a low sheet resistance of 26.8 Ω/sq at 91% transmittance (at 550 nm), improves surface smoothness, and enhances mechanical properties assisted by an amphiphilic fluoro-surfactant. The polymeric light-emitting diodes (PLEDs) and organic solar cells (OSCs) using the AgNW/PEDOT:PSS composite electrode showed higher device performances than those with AgNW and PEDOT:PSS electrodes and excellent flexibility under bending test. These results indicates that the AgNW/PEDOT:PSS composite presented is a good candidate as next-generation transparent elelctrodes for applications into flexible optoelectronic devices. [Figure not available: see fulltext.

Nitrogen grain-boundary passivation of In-doped ZnO transparent conducting oxide

NASA Astrophysics Data System (ADS)

Ali, D.; Butt, M. Z.; Coughlan, C.; Caffrey, D.; Shvets, I. V.; Fleischer, K.

2018-04-01

We have investigated the properties and conduction limitations of spray pyrolysis grown, low-cost transparent conducting oxide ZnO thin films doped with indium. We analyze the optical, electrical, and crystallographic properties as functions of In content with a specific focus on postgrowth heat treatment of these thin films at 320 ∘C in an inert, nitrogen atmosphere, which improves the films electrical properties considerably. The effect was found to be dominated by nitrogen-induced grain-boundary passivation, identified by a combined study using i n situ resistance measurement upon annealing, x-ray photoelectron spectroscopy, photoluminescence, and x-ray diffraction studies. We also highlight the chemical mechanism of morphologic and crystallographic changes found in films with high indium content. By optimizing growth conditions according to these findings, ZnO:In with a resistivity as low as 2 ×10 -3Ω cm , high optical quality (T ≈90 % ), and sheet resistance of 32 Ω /□ has been obtained without any need for postgrowth treatments.

Spray-Deposited Large-Area Copper Nanowire Transparent Conductive Electrodes and Their Uses for Touch Screen Applications.

PubMed

Chu, Hsun-Chen; Chang, Yen-Chen; Lin, Yow; Chang, Shu-Hao; Chang, Wei-Chung; Li, Guo-An; Tuan, Hsing-Yu

2016-05-25

Large-area conducting transparent conducting electrodes (TCEs) were prepared by a fast, scalable, and low-cost spray deposition of copper nanowire (CuNW) dispersions. Thin, long, and pure copper nanowires were obtained via the seed-mediated growth in an organic solvent-based synthesis. The mean length and diameter of nanowires are, respectively, 37.7 μm and 46 nm, corresponding to a high-mean-aspect ratio of 790. These wires were spray-deposited onto a glass substrate to form a nanowire conducting network which function as a TCE. CuNW TCEs exhibit high-transparency and high-conductivity since their relatively long lengths are advantageous in lowering in the sheet resistance. For example, a 2 × 2 cm(2) transparent nanowire electrode exhibits transmittance of T = 90% with a sheet resistance as low as 52.7 Ω sq(-1). Large-area sizes (>50 cm(2)) of CuNW TCEs were also prepared by the spray coating method and assembled as resistive touch screens that can be integrated with a variety of devices, including LED lighting array, a computer, electric motors, and audio electronic devices, showing the capability to make diverse sizes and functionalities of CuNW TCEs by the reported method.

The Electric Car Challenge.

ERIC Educational Resources Information Center

Diehl, Brian E.

1997-01-01

Describes the Electric Car Challenge during which students applied methods of construction to build lightweight, strong vehicles that were powered by electricity. The activity required problem solving, sheet metal work, electricity, design, and construction skills. (JOW)

High Transparent and Conductive TiO2/Ag/TiO2 Multilayer Electrode Films Deposited on Sapphire Substrate

NASA Astrophysics Data System (ADS)

Loka, Chadrasekhar; Moon, Sung Whan; Choi, YiSik; Lee, Kee-Sun

2018-03-01

Transparent conducting oxides attract intense interests due to its diverse industrial applications. In this study, we report sapphire substrate-based TiO2/Ag/TiO2 (TAT) multilayer structure of indium-free transparent conductive multilayer coatings. The TAT thin films were deposited at room temperature on sapphire substrates and a rigorous analysis has been presented on the electrical and optical properties of the films as a function of Ag thickness. The optical and electrical properties were mainly controlled by the Ag mid-layer thickness of the TAT tri-layer. The TAT films showed high luminous transmittance 84% at 550 nm along with noteworthy low electrical resistance 3.65 × 10-5 Ω-cm and sheet resistance of 3.77 Ω/square, which is better are than those of amorphous ITO films and any sapphire-based dielectric/metal/dielectric multilayer stack. The carrier concentration of the films was increased with respect to Ag thickness. We obtained highest Hackke's figure of merit 43.97 × 10-3 Ω-1 from the TAT multilayer thin film with a 16 nm thick Ag mid-layer.

Ultra-flexible and robust transparent electrodes by embedding silver nanowires into polyimide matrix

NASA Astrophysics Data System (ADS)

Zhao, Rong Rong; Yu, Ming Shi; Wang, Guan Cheng; Liu, Wei; Chen, Tong Lai

2018-06-01

Silver nanowires (AgNWs) percolated films have been extensively considered as promising candidates for alternative transparent electrodes. However, due to their high surface roughness, poor adhesion and thermal stability, their practical use in transparent conducting film application is still heavily limited. In this paper, we report ultra-flexible transparent electrodes by imbedding AgNWs into polyimide (PI) thin films to achieve smooth surface, pronounced thermal stability, and high adhesion. Besides the excellent electrical conductivity of about 7-13Ω/□ in sheet resistance, the obtained AgNWs/PI films have excellent transparency and mechanical resilience due to the intrinsic physical and chemical properties of PI organic polymer. By embedding AgNWs into PI, the surface roughness of AgNWs percolated films can be reduced from 39.5 nm to 6 nm (RMS values), and the adhesion of AgNWs to PI is greatly enhanced if compared to the case of only AgNWs onto glass or plastic substrates. Additionally, the AgNWs/PI films show extraordinary stability in terms of electrical conductivity after the arbitrary twisting and thermal heating test, respectively, which are demonstrated by the electrical-thermal measurements via thermal IR imaging.

System for harvesting water wave energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhong Lin; Su, Yanjie; Zhu, Guang

A generator for harvesting energy from water in motion includes a sheet of a hydrophobic material, having a first side and an opposite second side, that is triboelectrically more negative than water. A first electrode sheet is disposed on the second side of the sheet of a hydrophobic material. A second electrode sheet is disposed on the second side of the sheet of a hydrophobic material and is spaced apart from the first electrode sheet. Movement of the water across the first side induces an electrical potential imbalance between the first electrode sheet and the second electrode sheet.

Effects of electron pressure anisotropy on current sheet configuration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Artemyev, A. V., E-mail: aartemyev@igpp.ucla.edu; Angelopoulos, V.; Runov, A.

2016-09-15

Recent spacecraft observations in the Earth's magnetosphere have demonstrated that the magnetotail current sheet can be supported by currents of anisotropic electron population. Strong electron currents are responsible for the formation of very thin (intense) current sheets playing the crucial role in stability of the Earth's magnetotail. We explore the properties of such thin current sheets with hot isotropic ions and cold anisotropic electrons. Decoupling of the motions of ions and electrons results in the generation of a polarization electric field. The distribution of the corresponding scalar potential is derived from the electron pressure balance and the quasi-neutrality condition. Wemore » find that electron pressure anisotropy is partially balanced by a field-aligned component of this polarization electric field. We propose a 2D model that describes a thin current sheet supported by currents of anisotropic electrons embedded in an ion-dominated current sheet. Current density profiles in our model agree well with THEMIS observations in the Earth's magnetotail.« less

One-step synthesis of graphene nanoribbon-MnO₂ hybrids and their all-solid-state asymmetric supercapacitors.

PubMed

Liu, Mingkai; Tjiu, Weng Weei; Pan, Jisheng; Zhang, Chao; Gao, Wei; Liu, Tianxi

2014-04-21

Three-dimensional (3D) hierarchical hybrid nanomaterials (GNR-MnO₂) of graphene nanoribbons (GNR) and MnO₂ nanoparticles have been prepared via a one-step method. GNR, with unique features such as high aspect ratio and plane integrity, has been obtained by longitudinal unzipping of multi-walled carbon nanotubes (CNTs). By tuning the amount of oxidant used, different mass loadings of MnO₂ nanoparticles have been uniformly deposited on the surface of GNRs. Asymmetric supercapacitors have been fabricated with the GNR-MnO₂ hybrid as the positive electrode and GNR sheets as the negative electrode. Due to the desirable porous structure, excellent electrical conductivity, as well as high rate capability and specific capacitances of both the GNR and GNR-MnO₂ hybrid, the optimized GNR//GNR-MnO₂ asymmetric supercapacitor can be cycled reversibly in an enlarged potential window of 0-2.0 V. In addition, the fabricated GNR//GNR-MnO₂ asymmetric supercapacitor exhibits a significantly enhanced maximum energy density of 29.4 W h kg(-1) (at a power density of 12.1 kW kg(-1)), compared with that of the symmetric cells based on GNR-MnO₂ hybrids or GNR sheets. This greatly enhanced energy storage ability and high rate capability can be attributed to the homogeneous dispersion and excellent pseudocapacitive performance of MnO₂ nanoparticles and the high electrical conductivity of the GNRs.

Radiation-induced deposition of transparent conductive tin oxide coatings

NASA Astrophysics Data System (ADS)

Umnov, S.; Asainov, O.; Temenkov, V.

2016-04-01

The study of tin oxide films is stimulated by the search for an alternative replacement of indium-tin oxide (ITO) films used as transparent conductors, oxidation catalysts, material gas sensors, etc. This work was aimed at studying the influence of argon ions irradiation on optical and electrical characteristics of tin oxide films. Thin films of tin oxide (without dopants) were deposited on glass substrates at room temperature using reactive magnetron sputtering. After deposition, the films were irradiated with an argon ion beam. The current density of the beam was (were) 2.5 mA/cm2, and the particles energy was 300-400 eV. The change of the optical and electrical properties of the films depending on the irradiation time was studied. Films optical properties were investigated by photometry in the range of 300-1100 nm. Films structural properties were studied using X-ray diffraction. The diffractometric research showed that the films, deposited on a substrate, had a crystal structure, and after argon ions irradiation they became quasi-crystalline (amorphous). It has been found that the transmission increases proportionally with the irradiation time, however the sheet resistance increases disproportionally. Tin oxide films (thickness ~30 nm) with ~100% transmittance and sheet resistance of ~100 kOhm/sq. were obtained. The study has proved to be prospective in the use of ion beams to improve the properties of transparent conducting oxides.

Transparent, Weakly Conductive Films for Space Applications

NASA Astrophysics Data System (ADS)

Griffin, John; Morgan, Ashraf; Hambourger, Paul

2004-10-01

Electrically insulating spacecraft surfaces are vulnerable to nonuniform charge buildup due to particles emitted by the sun. On Mars, insulating surfaces of exploration vehicles and structures will be affected by dust coatings possibly held in place by triboelectric surface charge. Application of a conductive film may be a solution to the charging problem, but the coating must be highly transparent if used on solar panels, lenses, etc. Sheet resistivity requirements depend on the application and are in the range 10^2-10^8 ohms/square. Co-deposited indium tin oxide (ITO) and MgF2 is promising, with high transparency, tailorable electrical properties, and durability to atomic oxygen.(Joyce A. Dever et al., NASA TM 1998-208499 (August 1998).) Due to ITO's relatively narrow bandgap ( ˜3.5 eV), the film might absorb enough ultraviolet to protect polymeric substrates. Recent work on dual-magnetron-sputtered ITO-MgF2 showed that a variety of polymeric substrates can be coated at room temperature.(Thomas Cashman et al., Vacuum Technology & Coating, September 2003, p. 38.) However, the sheet resistivity is very sensitive to composition, suggestive of a percolation transition. This could be a serious problem for large-scale coating production. We will report on attempts to control film composition by plasma emission monitoring of the ITO and MgF2 guns. Supported by NASA Glenn Research Center, Cooperative Agreements NCC3-1033 and NCC3-1065.

Wettability Investigations and Wet Transfer Enhancement of Large-Area CVD-Graphene on Aluminum Nitride

PubMed Central

Knapp, Marius; Hoffmann, René; Cimalla, Volker; Ambacher, Oliver

2017-01-01

The two-dimensional and virtually massless character of graphene attracts great interest for radio frequency devices, such as surface and bulk acoustic wave resonators. Due to its good electric conductivity, graphene might be an alternative as a virtually massless electrode by improving resonator performance regarding mass-loading effects. We report on an optimization of the commonly used wet transfer technique for large-area graphene, grown via chemical vapor deposition, onto aluminum nitride (AlN), which is mainly used as an active, piezoelectric material for acoustic devices. Today, graphene wet transfer is well-engineered for silicon dioxide (SiO2). Investigations on AlN substrates reveal highly different surface properties compared to SiO2 regarding wettability, which strongly influences the quality of transferred graphene monolayers. Both physical and chemical effects of a plasma treatment of AlN surfaces change wettability and avoid large-scale cracks in the transferred graphene sheet during desiccation. Spatially-resolved Raman spectroscopy reveals a strong strain and doping dependence on AlN plasma pretreatments correlating with the electrical conductivity of graphene. In our work, we achieved transferred crack-free large-area (40 × 40 mm2) graphene monolayers with sheet resistances down to 350 Ω/sq. These achievements make graphene more powerful as an eco-friendly and cheaper replacement for conventional electrode materials used in radio frequency resonator devices. PMID:28820462

Industrial graphene metrology.

PubMed

Kyle, Jennifer Reiber; Ozkan, Cengiz S; Ozkan, Mihrimah

2012-07-07

Graphene is an allotrope of carbon whose structure is based on one-atom-thick planar sheets of carbon atoms that are densely packed in a honeycomb crystal lattice. Its unique electrical and optical properties raised worldwide interest towards the design and fabrication of future electronic and optical devices with unmatched performance. At the moment, extensive efforts are underway to evaluate the reliability and performance of a number of such devices. With the recent advances in synthesizing large-area graphene sheets, engineers have begun investigating viable methodologies for conducting graphene metrology and quality control at industrial scales to understand a variety of reliability issues including defects, patternability, electrical, and physical properties. This review summarizes the current state of industrial graphene metrology and provides an overview of graphene metrology techniques. In addition, a recently developed large-area graphene metrology technique based on fluorescence quenching is introduced. For each metrology technique, the industrial metrics it measures are identified--layer thickness, edge structure, defects, Fermi level, and thermal conductivity--and a detailed description is provided as to how the measurements are performed. Additionally, the potential advantages of each technique for industrial use are identified, including throughput, scalability, sensitivity to substrate/environment, and on their demonstrated ability to achieve quantified results. The recently developed fluorescence-quenching metrology technique is shown to meet all the necessary criteria for industrial applications, rendering it the first industry-ready graphene metrology technique.

Influence of Crack-Tip Configurations on the Fracture Response of 0.04-Inch Thick 2024-T3 Aluminum Alloy Sheet

NASA Technical Reports Server (NTRS)

Johnston, William M.; Newman, James C. (Technical Monitor)

2002-01-01

A series of fracture tests were conducted on Middle-crack tension M(T) and compact tension C(T) specimens to determine the effects of specimen type, specimen width, notch tip sharpness and buckling on the fracture behavior of cracked thin sheet (0.04 inch thick) 2024-T3 aluminum alloy material. A series of M(T) specimens were tested with three notch tip configurations: (1) a fatigue pre-cracked notch, (2) a 0.010-inch-diameter wire electrical discharge machined (EDM) notch, and (3) a EDM notch sharpened with a razor blade. The test procedures are discussed and the experimental results for failure stress, load vs. crack extension and the material stress-strain response are reported.

Spectroscopic Diagnostics of Electric Fields in the Plasma of Current Sheets

NASA Astrophysics Data System (ADS)

Gavrilenko, Valeri; Kyrie, Natalya P.; Frank, Anna G.; Oks, Eugene

2004-11-01

Spectroscopic measurements of electric fields (EFs) in current sheet plasmas were performed in the CS-3D device. The device is intended to study the evolution of current sheets and the magnetic reconnection phenomena. We used the broadening of spectral lines (SLs) of HeII ions for diagnostics of EFs in the current sheet middle plane, and the broadening of SLs of HeI atoms for detection of EFs in the current sheet peripheral regions. For detection of EFs in current sheet plasma, we used SLs of HeII ions at 468.6; 320.3 and 656.0 nm, as well as SLs of HeI atoms at 667.8; 587.6; 492.2 and 447.1 nm. The latter two lines are of a special interest since their profiles include the dipole-forbidden components along with the allowed components. The experimental data have been analyzed by using the numerical calculations based on the Model Microfield Method. The maximum plasma density in the middle of the sheet was in the range (2-8) × 10^16 cm-3, the density in the peripheral regions was (1-2)×10^15 cm-3, and the strength of the quasi-one-dimensional anomalous electric fields in the peripheral regions reached the value of 100 kV/cm. Supported by CRDF, grant RU-P1-2594-MO-04; by the RFBR, grant 03-02-17282; and by the ISTC, project 2098.

Antimony-Doped Tin Oxide Thin Films Grown by Home Made Spray Pyrolysis Technique

NASA Astrophysics Data System (ADS)

Yusuf, Gbadebo; Babatola, Babatunde Keji; Ishola, Abdulahi Dimeji; Awodugba, Ayodeji O.; Solar cell Collaboration

2016-03-01

Transparent conducting antimony-doped tin oxide (ATO) films have been deposited on glass substrates by home made spray pyrolysis technique. The structural, electrical and optical properties of the ATO films have been investigated as a function of Sb-doping level and annealing temperature. The optimum target composition for high conductivity and low resistivity was found to be 20 wt. % SnSb2 + 90 wt. ATO. Under optimized deposition conditions of 450oC annealing temperature, electrical resistivity of 5.2×10-4 Ω -cm, sheet resistance of 16.4 Ω/sq, average optical transmittance of 86% in the visible range, and average optical band-gap of 3.34eV were obtained. The film deposited at lower annealing temperature shows a relatively rough, loosely bound slightly porous surface morphology while the film deposited at higher annealing temperature shows uniformly distributed grains of greater size. Keywords: Annealing, Doping, Homemade spray pyrolysis, Tin oxide, Resistivity

Characterization of Epoxy Functionalized Graphite Nanoparticles and the Physical Properties of Epoxy Matrix Nanocomposites

NASA Technical Reports Server (NTRS)

Miller, Sandi G.; Bauer, Jonathan L.; Maryanski, Michael J.; Heimann, Paula J.; Barlow, Jeremy P.; Gosau, Jan-Michael; Allred, Ronald E.

2010-01-01

This work presents a novel approach to the functionalization of graphite nanoparticles. The technique provides a mechanism for covalent bonding between the filler and matrix, with minimal disruption to the sp2 hybridization of the pristine graphene sheet. Functionalization proceeded by covalently bonding an epoxy monomer to the surface of expanded graphite, via a coupling agent, such that the epoxy concentration was measured as approximately 4 wt.%. The impact of dispersing this material into an epoxy resin was evaluated with respect to the mechanical properties and electrical conductivity of the graphite-epoxy nanocomposite. At a loading as low as 0.5 wt.%, the electrical conductivity was increased by five orders of magnitude relative to the base resin. The material yield strength was increased by 30% and Young s modulus by 50%. These results were realized without compromise to the resin toughness.

Electrically tunable coherent optical absorption in graphene with ion gel.

PubMed

Thareja, Vrinda; Kang, Ju-Hyung; Yuan, Hongtao; Milaninia, Kaveh M; Hwang, Harold Y; Cui, Yi; Kik, Pieter G; Brongersma, Mark L

2015-03-11

We demonstrate electrical control over coherent optical absorption in a graphene-based Salisbury screen consisting of a single layer of graphene placed in close proximity to a gold back reflector. The screen was designed to enhance light absorption at a target wavelength of 3.2 μm by using a 600 nm-thick, nonabsorbing silica spacer layer. An ionic gel layer placed on top of the screen was used to electrically gate the charge density in the graphene layer. Spectroscopic reflectance measurements were performed in situ as a function of gate bias. The changes in the reflectance spectra were analyzed using a Fresnel based transfer matrix model in which graphene was treated as an infinitesimally thin sheet with a conductivity given by the Kubo formula. The analysis reveals that a careful choice of the ionic gel layer thickness can lead to optical absorption enhancements of up to 5.5 times for the Salisbury screen compared to a suspended sheet of graphene. In addition to these absorption enhancements, we demonstrate very large electrically induced changes in the optical absorption of graphene of ∼3.3% per volt, the highest attained so far in a device that features an atomically thick active layer. This is attributable in part to the more effective gating achieved with the ion gel over the conventional dielectric back gates and partially by achieving a desirable coherent absorption effect linked to the presence of the thin ion gel that boosts the absorption by 40%.

Influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric current and electron density in current sheets formed in helium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ostrovskaya, G. V., E-mail: galya-ostr@mail.ru; Markov, V. S.; Frank, A. G., E-mail: annfrank@fpl.gpi.ru

The influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric current and electron density in current sheets formed in helium plasma in 2D and 3D magnetic configurations with X-type singular lines is studied by the methods of holographic interferometry and magnetic measurements. Significant differences in the structures of plasma and current sheets formed at close parameters of the initial plasma and similar configurations of the initial magnetic fields are revealed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoshimoto, Shinya, E-mail: yosshi@issp.u-tokyo.ac.jp; Shiozawa, Yuichiro; Koitaya, Takanori

Electronic states and electrical conductivity of the native oxide Si(111) surface adsorbed with an electron donor tetrakis(dimethylamino)ethylene (TDAE) were investigated using ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy (XPS), and independently driven four-probe conductivity measurements. The formation of positively charged TDAE species is confirmed by the downward shift of the vacuum level by 1.45 eV, the absence of HOMO level in the valence band, and observation of the positively charged state in the N 1s XPS spectra. Si 2p XPS spectra and four-probe conductivity measurements revealed that TDAE adsorption induces an increase in downward band bending and a reduction in electrical resistancemore » of the surface, respectively. The sheet conductivity and the electron density of the surface are 1.1 μS/◻ and 4.6 × 10{sup 9} cm{sup −2}, respectively, after TDAE adsorption, and they are as high as 350% of the original surface. These results demonstrate that the electron density of the semiconductor surface is successfully controlled by the electron donor molecule TDAE.« less

Low-temperature thermal reduction of graphene oxide: In situ correlative structural, thermal desorption, and electrical transport measurements

NASA Astrophysics Data System (ADS)

Lipatov, Alexey; Guinel, Maxime J.-F.; Muratov, Dmitry S.; Vanyushin, Vladislav O.; Wilson, Peter M.; Kolmakov, Andrei; Sinitskii, Alexander

2018-01-01

Elucidation of the structural transformations in graphene oxide (GO) upon reduction remains an active and important area of research. We report the results of in situ heating experiments, during which electrical, mass spectrometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM) measurements were carried out correlatively. The simultaneous electrical and temperature programmed desorption measurements allowed us to correlate the onset of the increase in the electrical conductivity of GO by five orders of magnitude at about 150 °C with the maxima of the rates of desorption of H2O, CO, and CO2. Interestingly, this large conductivity change happens at an intermediate level of the reduction of GO, which likely corresponds to the point when the graphitic domains become large enough to enable percolative electronic transport. We demonstrate that the gas desorption is intimately related to (i) the changes in the chemical structure of GO detected by XPS and Raman spectroscopy and (ii) the formation of nanoscopic holes in GO sheets revealed by TEM. These in situ observations provide a better understanding of the mechanism of the GO thermal reduction.

Fabrication of electric papers of graphene nanosheet shelled cellulose fibres by dispersion and infiltration as flexible electrodes for energy storage.

PubMed

Kang, Yan-Ru; Li, Ya-Li; Hou, Feng; Wen, Yang-Yang; Su, Dong

2012-05-21

An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω□(-1) and a conductivity of 11.6 S m(-1). The application of the composite paper as a flexible double layer supercapacitor in an organic electrolyte (LiPF(6)) displays a high capacity of 252 F g(-1) at a current density of 1 A g(-1) with respect to GNS. Moreover, the paper can be used as the anode in a lithium battery, showing distinct charge and discharge performances. The simple process for synthesising the GNS functionalized cellulose papers is attractive for the development of high performance papers for electrical, electrochemical and multifunctional applications.

Silver Flakes and Silver Dendrites for Hybrid Electrically Conductive Adhesives with Enhanced Conductivity

NASA Astrophysics Data System (ADS)

Ma, Hongru; Li, Zhuo; Tian, Xun; Yan, Shaocun; Li, Zhe; Guo, Xuhong; Ma, Yanqing; Ma, Lei

2018-03-01

Silver dendrites were prepared by a facile replacement reaction between silver nitrate and zinc microparticles of 20 μm in size. The influence of reactant molar ratio, reaction solution volume, silver nitrate concentration, and reaction time on the morphology of dendrites was investigated systematically. It was found that uniform tree-like silver structures are synthesized under the optimal conditions. Their structure can be described as a trunk, symmetrical branches, and leaves, which length scales of 5-10, 1-2 μm, and 100-300 nm, respectively. All features were systematically characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and x-ray powder diffraction. A hybrid fillers system using silver flakes and dendrites as electrically conductive adhesives (ECAs) exhibited excellent overall performance. This good conductivity can be attributed mainly to the synergy between the silver microflakes (5-20 μm sized irregular sheet structures) and dendrites, allowing more conductive pathways to be formed between the fillers. In order to further optimize the overall electrical conductivity, various mixtures of silver microflakes and silver dendrites were tested in ECAs, with results indicating that the highest conductivity was shown when the amounts of silver microflakes, silver dendrites and the polymer matrix were 69.4 wt.% (20.82 vol.%), 0.6 wt.% (0.18 vol.%), and 30.0 wt.% (79.00 vol.%), respectively. The corresponding mass ratio of silver flakes to silver dendrites was 347:3. The resistivity of ECAs reached as low as 1.7 × 10-4 Ω cm.

New Materials for Structural Composites and Protective Coatings

NASA Technical Reports Server (NTRS)

2008-01-01

The objective of this Phase I project was to create novel conductive materials that are lightweight and strong enough for multiple ground support equipment and Exploration applications. The long-term goal is to combine these materials within specially designed devices to create composites or coatings with diagnostic capabilities, increased strength, and tunable properties such as transparency, electroluminescence, and fire resistance. One such technology application is a smart windows system. In such a system, the transmission of light through a window is controlled by electrical power. In the future, these materials may also be able to absorb sunlight and convert it into electrical energy to produce light, thereby creating a self-sufficient lighting system. This experiment, conducted in collaboration with the Georgia Institute of Technology, demonstrated enhancements in fabricating fiber materials from carbon nanotubes (CNT). These nanotubes were grown as forests in an ultra-high-purity chemical vapor deposition (CVD) furnace and then drawn, using novel processing techniques, into fibers and yarns that would be turned into filaments. This work was submitted to the Journal of Advanced Functional Materials. The CNT fibers were initially tested as filament materials at atmospheric pressure; however, even under high current loads, the filaments produced only random sparking. The CNT fibers were also converted into transparent, hydrophobic, and conductive sheets. Filament testing at low vacuum pressures is in progress, and the technology will be enhanced in 2008. As initial proof of the smart-windows application concept, the use of CNT sheets as composites/ protective coatings was demonstrated in collaboration with Nanocomp Technologies of Concord, New Hampshire.

Electric fields in the plasma sheet and plasma sheet boundary layer

NASA Technical Reports Server (NTRS)

Pedersen, A.; Cattell, C. A.; Faelthammar, C. G.; Knott, K.; Lindqvist, P. A.; Manka, R. H.; Mozer, F. S.

1984-01-01

Data from the spherical double probe electric-field experiment on ISEE-1 were used to study plasmasheet/lobe boundary crossings during substorms, identified by plasma measurements and by using the electric field probes as a reference for measurements of the spacecraft potential. There are strong electric fields, with a dominant dawn-to-dusk component, throughout the boundary layer outside the plasmasheet for contracting and expanding motions of the plasmasheet and for different magnetic field directions. Characteristic amplitudes and durations are 5 to 10 mV/m and 5 to 15 min. The corresponding E x B vectors are always towards the plasmasheet.

Effect of Se addition on optical and electrical properties of chalcogenide CdSSe thin films

NASA Astrophysics Data System (ADS)

Hassanien, A. S.; Akl, Alaa A.

2016-01-01

Compositional dependence of optical and electrical properties of chalcogenide CdSxSe1-x (0.4 ≥ x ≥ 0.0 at. %) thin films was studied. Cadmium sulphoselenide films were deposited by thermal evaporation technique at vacuum (8.2 × 10-4 Pa) onto preheated glass substrates (523 K). The evaporation rate and film thickness were kept constant at 2.50 nm/s and 375 ± 5 nm, respectively. X-ray diffractograms showed that, the deposited films have the low crystalline nature. Energy dispersive analysis by X-ray (EDAX) was used to check the compositional elements of deposited films. The absorption coefficient was determined from transmission and reflection measurements at room temperature in the wavelength range 300-2500 nm. Optical density, skin depth, optical energy gap and Urbach's parameters of CdSSe thin films have also been estimated. The direct optical energy gap decreased from 2.248 eV to 1.749 eV when the ratio of Se-content was increased from 0.60 to 1.00 . Conduction band and valance band positions were evaluated. The temperature dependence of dc-electrical resistivity in the temperature range (293-450 K) has been reported. Three conduction regions due to different conduction mechanisms were detected. Electrical sheet resistance, activation energy and pre-exponential parameters were discussed. The estimated values of optical and electrical parameters were strongly dependent upon the Se-content in CdSSe matrix.

Wearable Electricity Generators Fabricated Utilizing Transparent Electronic Textiles Based on Polyester/Ag Nanowires/Graphene Core-Shell Nanocomposites.

PubMed

Wu, Chaoxing; Kim, Tae Whan; Li, Fushan; Guo, Tailiang

2016-07-26

The technological realization of wearable triboelectric generators is attractive because of their promising applications in wearable self-powered intelligent systems. However, the low electrical conductivity, the low electrical stability, and the low compatibility of current electronic textiles (e-textiles) and clothing restrict the comfortable and aesthetic integration of wearable generators into human clothing. Here, we present high-performance, transparent, smart e-textiles that employ commercial textiles coated with silver nanowire/graphene sheets fabricated by using a scalable, environmentally friendly, full-solution process. The smart e-textiles show superb and stable conduction of below 20 Ω/square as well as excellent flexibility, stretchability, foldability, and washability. In addition, wearable electricity-generating textiles, in which the e-textiles act as electrodes as well as wearable substrates, are presented. Because of the high compatibility of smart e-textiles and clothing, the electricity-generating textiles can be easily integrated into a glove to harvest the mechanical energy induced by the motion of the fingers. The effective output power generated by a single generator due to that motion reached as high as 7 nW/cm(2). The successful demonstration of the electricity-generating glove suggests a promising future for polyester/Ag nanowire/graphene core-shell nanocomposite-based smart e-textiles for real wearable electronic systems and self-powered clothing.

Light-weight free-standing carbon nanotube-silicon films for anodes of lithium ion batteries.

PubMed

Cui, Li-Feng; Hu, Liangbing; Choi, Jang Wook; Cui, Yi

2010-07-27

Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the infiltrated CNT network functions as both mechanical support and electrical conductor and Si as a high capacity anode material for Li-ion battery. Such free-standing film has a low sheet resistance of approximately 30 Ohm/sq. It shows a high specific charge storage capacity (approximately 2000 mAh/g) and a good cycling life, superior to pure sputtered-on silicon films with similar thicknesses. Scanning electron micrographs show that Si is still connected by the CNT network even when small breaking or cracks appear in the film after cycling. The film can also "ripple up" to release the strain of a large volume change during lithium intercalation. The conductive composite film can function as both anode active material and current collector. It offers approximately 10 times improvement in specific capacity compared with widely used graphite/copper anode sheets.

A statistical study of the inner edge of the electron plasma sheet and the net convection potential as a function of geomagnetic activity

NASA Astrophysics Data System (ADS)

Jiang, F.; Kivelson, M. G.; Walker, R. J.; Khurana, K. K.; Angelopoulos, V.; Hsu, T.

2011-06-01

A widely accepted explanation of the location of the inner edge of the electron plasma sheet and its dependence on electron energy is based on drift motions of individual particles. The boundary is identified as the separatrix between drift trajectories linking the tail to the dayside magnetopause (open paths) and trajectories closed around the Earth. A statistical study of the inner edge of the electron plasma sheet using THEMIS Electrostatic Analyzer plasma data from November 2007 to April 2009 enabled us to examine this model. Using a dipole magnetic field and a Volland-Stern electric field with shielding, we find that a steady state drift boundary model represents the average location of the electron plasma sheet boundary and reflects its variation with the solar wind electric field in the local time region between 21:00 and 06:00, except at high activity levels. However, the model does not reproduce the observed energy dispersion of the boundaries. We have also used the location of the inner edge of the electron plasma sheet to parameterize the potential drop of the tail convection electric field as a function of solar wind electric field (Esw) and geomagnetic activity. The range of Esw examined is small because the data were acquired near solar minimum. For the range of values tested (meaningful statistics only for Esw < 2 mV/m), reasonably good agreement is found between the potential drop of the tail convection electric field inferred from the location of the inner edge and the polar cap potential drop calculated from the model of Boyle et al. (1997).

The rolling performance of Fe-6.5 wt.% Si sheets edged with stainless steel

NASA Astrophysics Data System (ADS)

Zhang, B.; Ye, F.; Liang, Y. F.; Shi, X. J.; Lin, J. P.

2017-10-01

Compared with common electrical steel, high silicon electrical steel (Fe-6.5 wt.% Si alloy) exhibits excellent soft magnetic properties and a wide application prospect in high frequency electromagnetic fields. In the process of cold rolling Fe-6.5 wt.% Si alloy, edge-crack often occurs on the sheets due to the inadequate ductility and limited formability. It was found that the Fe-6.5 wt.% Si alloy sheet edged with 304 stainless steel by laser welding show an improved rolling performance. The composite sheet could be cold rolled to a thickness of 0.07 mm without observed edge cracks. The mechanical property of the edging material should be in an appropriate window in reference to that of the Fe-6.5 wt.% Si alloy.

Nonparaxial fractional Bessel and Bessel-Gauss auto-focusing light-sheet pincers and their higher-order spatial derivatives

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2017-05-01

Nonparaxial fractional electromagnetic Bessel and Bessel-Gauss auto-focusing light-sheet solutions and their spatial derivatives are synthesized stemming from the angular spectrum decomposition in plane waves. The propagation characteristics of these transverse electric-polarized light-sheets are analyzed by computing the radiated component of the incident electric field. Tight bending of the beam along curved trajectories and slit openings are observed, which could offer unique features and potential applications in the development of improved methods and devices in light-sheet tweezers for particle manipulation applications and dynamics in opto-fluidics, particle sizing and imaging to name a few examples. Moreover, computations of the scattering, radiation force and torque, and particle dynamics also benefit from the developed beam solutions.

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.

NREL Paves the Way to Commercialization of Silicon Ink (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

In 2008, Innovalight, a start-up company in Sunnyvale, California, invented a liquid form of silicon, called Silicon Ink. It contains silicon nanoparticles that are suspended evenly within the solution. Those nanoparticles contain dopant atoms that can be driven into silicon solar cells, which changes the conductivity of the silicon and creates the internal electric fields that are needed to turn photons into electrons -- and thus into electricity. The ink is applied with a standard screen printer, already commonly used in the solar industry. The distinguishing feature of Silicon Ink is that it can be distributed in exact concentrations inmore » precisely the correct locations on the surface of the solar cell. This allows most of the surface to be lightly doped, enhancing its response to blue light, while heavily doping the area around the electrical contacts, raising the conductivity in that area to allow the contact to work more efficiently. The accuracy and uniformity of the ink distribution allows the production of solar cells that achieve higher power production at a minimal additional cost.« less

Fabrication of textured SnO2 transparent conductive films using self-assembled Sn nanospheres

NASA Astrophysics Data System (ADS)

Fukumoto, Michitaka; Nakao, Shoichiro; Hirose, Yasushi; Hasegawa, Tetsuya

2018-06-01

We present a novel method to fabricate textured surfaces on transparent conductive SnO2 films by processing substrates through a bottom-up technique with potential for industrially scalable production. The substrate processing consists of three steps: deposition of precursor Sn films on glass substrates, formation of a self-assembled Sn nanosphere layer with reductive annealing, and conversion of Sn to SnO2 by oxidative annealing. Ta-doped SnO2 films conformally deposited on the self-assembled nanospherical SnO2 templates exhibited attractive optical and electrical properties, namely, enhanced haze values and low sheet resistances, for applications as transparent electrodes in photovoltaics.

Large-area graphene films by simple solution casting of edge-selectively functionalized graphite.

PubMed

Bae, Seo-Yoon; Jeon, In-Yup; Yang, Jieun; Park, Noejung; Shin, Hyeon Suk; Park, Sungjin; Ruoff, Rodney S; Dai, Liming; Baek, Jong-Beom

2011-06-28

We report edge-selective functionalization of graphite (EFG) for the production of large-area uniform graphene films by simply solution-casting EFG dispersions in dichloromethane on silicon oxide substrates, followed by annealing. The resultant graphene films show ambipolar transport properties with sheet resistances of 0.52-3.11 kΩ/sq at 63-90% optical transmittance. EFG allows solution processing methods for the scalable production of electrically conductive, optically transparent, and mechanically robust flexible graphene films for use in practice.

Computer-Aided Engineering Of Cabling

NASA Technical Reports Server (NTRS)

Billitti, Joseph W.

1989-01-01

Program generates data sheets, drawings, and other information on electrical connections. DFACS program, centered around single data base, has built-in menus providing easy input of, and access to, data for all personnel involved in system, subsystem, and cabling. Enables parallel design of circuit-data sheets and drawings of harnesses. Also recombines raw information to generate automatically various project documents and drawings, including index of circuit-data sheets, list of electrical-interface circuits, lists of assemblies and equipment, cabling trees, and drawings of cabling electrical interfaces and harnesses. Purpose of program to provide engineering community with centralized data base for putting in, and gaining access to, functional definition of system as specified in terms of details of pin connections of end circuits of subsystems and instruments and data on harnessing. Primary objective to provide instantaneous single point of interchange of information, thus avoiding

Impurity band conduction in reduced samples of bismuth iron molybdate

NASA Astrophysics Data System (ADS)

McIntyre, Shawn M.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Plasmonic Three-Dimensional Transparent Conductor Based on Al-Doped Zinc Oxide-Coated Nanostructured Glass Using Atomic Layer Deposition

DOE PAGES

Malek, Gary A.; Aytug, Tolga; Liu, Qingfeng; ...

2015-04-02

Transparent nanostructured glass coatings, fabricated on glass substrates, with a unique three-dimensional (3D) architecture were utilized as the foundation for the design of plasmonic 3D transparent conductors. Transformation of the non-conducting 3D structure to a conducting 3D network was accomplished through atomic layer deposition of aluminum-doped zinc oxide (AZO). After AZO growth, gold nanoparticles (AuNPs) were deposited by electronbeam evaporation to enhance light trapping and decrease the overall sheet resistance. Field emission scanning electron microscopy and atomic force microcopy images revealed the highly porous, nanostructured morphology of the AZO coated glass surface along with the in-plane dimensions of the depositedmore » AuNPs. Sheet resistance measurements conducted on the coated samples verified that the electrical properties of the 3D network are comparable to that of the untextured two-dimensional AZO coated glass substrates. In addition, transmittance measurements of the glass samples coated with various AZO thicknesses showed preservation of the highly transparent nature of each sample, while the AuNPs demonstrated enhanced light scattering as well as light-trapping capability.« less

Bis(aminothiolato)nickel nanosheet as a redox switch for conductivity and an electrocatalyst for the hydrogen evolution reaction† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc02688a

PubMed Central

Sun, Xinsen; Wu, Kuo-Hui; Sakamoto, Ryota; Kusamoto, Tetsuro; Maeda, Hiroaki; Ni, Xiaojuan; Jiang, Wei; Liu, Feng; Sasaki, Sono; Masunaga, Hiroyasu

2017-01-01

A π-conjugated coordination nanosheet comprising bis(aminothiolato)nickel (NiAT) moieties was synthesized by the reaction of Ni(acac)2 with 1,3,5-triaminobenzene-2,4,6-trithiol at liquid–liquid and gas–liquid interfaces. The sheet thickness could be controlled down to a single layer (0.6 nm). Selected area electron diffraction and grazing incidence X-ray diffraction analyses indicated the formation of a flat crystalline sheet with a kagome lattice stacked in a staggered alignment. NiAT was reversibly interconverted to a bis(iminothiolato)nickel (NiIT) nanosheet by the chemical 2H+–2e– reaction, which was accompanied by a drastic change in electrical conductivity from 3 × 10–6 to 1 × 10–1 S cm–1. This change in conductivity was explained by the difference in band structures between NiAT and NiIT. NiAT acted as an efficient electrocatalyst for the hydrogen evolution reaction, showing strong acid durability and an onset overpotential of –0.15 V. PMID:29568456

Plasmonic Three-Dimensional Transparent Conductor Based on Al-Doped Zinc Oxide-Coated Nanostructured Glass Using Atomic Layer Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malek, Gary A.; Aytug, Tolga; Liu, Qingfeng

Transparent nanostructured glass coatings, fabricated on glass substrates, with a unique three-dimensional (3D) architecture were utilized as the foundation for the design of plasmonic 3D transparent conductors. Transformation of the non-conducting 3D structure to a conducting 3D network was accomplished through atomic layer deposition of aluminum-doped zinc oxide (AZO). After AZO growth, gold nanoparticles (AuNPs) were deposited by electronbeam evaporation to enhance light trapping and decrease the overall sheet resistance. Field emission scanning electron microscopy and atomic force microcopy images revealed the highly porous, nanostructured morphology of the AZO coated glass surface along with the in-plane dimensions of the depositedmore » AuNPs. Sheet resistance measurements conducted on the coated samples verified that the electrical properties of the 3D network are comparable to that of the untextured two-dimensional AZO coated glass substrates. In addition, transmittance measurements of the glass samples coated with various AZO thicknesses showed preservation of the highly transparent nature of each sample, while the AuNPs demonstrated enhanced light scattering as well as light-trapping capability.« less

Solution-processed assembly of ultrathin transparent conductive cellulose nanopaper embedding AgNWs

NASA Astrophysics Data System (ADS)

Song, Yuanyuan; Jiang, Yaoquan; Shi, Liyi; Cao, Shaomei; Feng, Xin; Miao, Miao; Fang, Jianhui

2015-08-01

Natural biomass based cellulose nanopaper is becoming a promising transparent substrate to supersede traditional petroleum based polymer films in realizing future flexible paper-electronics. Here, ultrathin, highly transparent, outstanding conductive hybrid nanopaper with excellent mechanical flexibility was synthesized by the assembly of nanofibrillated cellulose (NFC) and silver nanowires (AgNWs) using a pressured extrusion paper-making technique. The hybrid nanopaper with a thickness of 4.5 μm has a good combination of transparent conductive performance and mechanical stability using bamboo/hemp NFC and AgNWs cross-linked by hydroxypropylmethyl cellulose (HPMC). The heterogeneous fibrous structure of BNFC/HNFC/AgNWs endows a uniform distribution and an enhanced forward light scattering, resulting in high electrical conductivity and optical transmittance. The hybrid nanopaper with an optimal weight ratio of BNFC/HNFC to AgNWs shows outstanding synergistic properties with a transmittance of 86.41% at 550 nm and a sheet resistance of 1.90 ohm sq-1, equal to the electronic conductivity, which is about 500 S cm-1. The BNFC/HNFC/AgNW hybrid nanopaper maintains a stable electrical conductivity after the peeling test and bending at 135° for 1000 cycles, indicating remarkably strong adhesion and mechanical flexibility. Of importance here is that the high-performance and low-cost hybrid nanopaper shows promising potential for electronics application in solar cells, flexible displays and other high-technology products.Natural biomass based cellulose nanopaper is becoming a promising transparent substrate to supersede traditional petroleum based polymer films in realizing future flexible paper-electronics. Here, ultrathin, highly transparent, outstanding conductive hybrid nanopaper with excellent mechanical flexibility was synthesized by the assembly of nanofibrillated cellulose (NFC) and silver nanowires (AgNWs) using a pressured extrusion paper-making technique. The hybrid nanopaper with a thickness of 4.5 μm has a good combination of transparent conductive performance and mechanical stability using bamboo/hemp NFC and AgNWs cross-linked by hydroxypropylmethyl cellulose (HPMC). The heterogeneous fibrous structure of BNFC/HNFC/AgNWs endows a uniform distribution and an enhanced forward light scattering, resulting in high electrical conductivity and optical transmittance. The hybrid nanopaper with an optimal weight ratio of BNFC/HNFC to AgNWs shows outstanding synergistic properties with a transmittance of 86.41% at 550 nm and a sheet resistance of 1.90 ohm sq-1, equal to the electronic conductivity, which is about 500 S cm-1. The BNFC/HNFC/AgNW hybrid nanopaper maintains a stable electrical conductivity after the peeling test and bending at 135° for 1000 cycles, indicating remarkably strong adhesion and mechanical flexibility. Of importance here is that the high-performance and low-cost hybrid nanopaper shows promising potential for electronics application in solar cells, flexible displays and other high-technology products. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03218k

High conductive and scalable Ag nanowires flexible transparent electrode by nanowelding with physical methods

NASA Astrophysics Data System (ADS)

He, W. W.; Yan, X. H.; Long, Y. F.; Liang, Y. M.; Pan, C.; Zhao, J. L.; Liu, Q. X.

2017-09-01

Transparent electrodes (TEs) are very important for electronic devices. At present, ITO is gaining the largest market share but will be reduced. Ag nanowires (AgNWs) TEs is acknowledged as one of the most potential alternative to ITO. However, AgNWs TEs still have electrical problems because of the low contact between the AgNWs. In this paper, we report three physics methods to increase the conductivity of AgNWs TEs by nanowelding the contact of nanowires. For heat-resistant materials, 200 °C heat-nanowelding can help to reduce the sheet resistance by 96.7%. For pressure resistant materials, 20MPa pressure-nanowelding can help to increase the conductivity by 98.7%. And the transmittance (>90%) remains constant during the above process. Yet, both of these methods cannot improve the adhesion between nanowires and the substrates. Luckily, tight adhesion can be obtained by overcoating a PEDOT: PSS lalyer on AgNWs film which can reduce the sheet resistance by 87.8%. This means that things are usually not perfect, and they have their own advantages and lay the foundation for the popularization and application of AgNWs TEs. In a word, these three nano-welding methods are all suit for manufacture on a large scale for high conductive AgNWs TEs.

Analysis and comparison of magnetic sheet insulation tests

NASA Astrophysics Data System (ADS)

Marion-Péra, M. C.; Kedous-Lebouc, A.; Cornut, B.; Brissonneau, P.

1994-05-01

Magnetic circuits of electrical machines are divided into coated sheets in order to limit eddy currents. The surface insulation resistance of magnetic sheets is difficult to evaluate because it depends on parameters like pressure and covers a wide range of values. Two methods of measuring insulation resistance are analyzed: the standardized 'Franklin device' and a tester developed by British Steel Electrical. Their main drawback is poor local repeatability. The Franklin method allows better quality control of industrial process because it measures only one insulating layer at a time. It also gives more accurate images of the distribution of possible defects. Nevertheless, both methods lead to similar classifications of insulation efficiency.

Two-dimensional potential double layers and discrete auroras

NASA Technical Reports Server (NTRS)

Kan, J. R.; Lee, L. C.; Akasofu, S.-I.

1979-01-01

This paper is concerned with the formation of the acceleration region for electrons which produce the visible auroral arc and with the formation of the inverted V precipitation region. The former is embedded in the latter, and both are associated with field-aligned current sheets carried by plasma sheet electrons. It is shown that an electron current sheet driven from the plasma sheet into the ionosphere leads to the formation of a two-dimensional potential double layer. For a current sheet of a thickness less than the proton gyrodiameter solutions are obtained in which the field-aligned potential drop is distributed over a length much greater than the Debye length. For a current sheet of a thickness much greater than the proton gyrodiameter solutions are obtained in which the potential drop is confined to a distance on the order of the Debye length. The electric field in the two-dimensional double-layer model is the zeroth-order field inherent to the current sheet configuration, in contrast to those models in which the electric field is attributed to the first-order field due to current instabilities or turbulences. The maximum potential in the two-dimensional double-layer models is on the order of the thermal energy of plasma sheet protons, which ranges from 1 to 10 keV.

Alternating-polarity operation for complete regeneration of electrochemical deionization system

DOEpatents

Tran, Tri D.; Lenz, David J.

2004-07-13

An electrically regeneratable battery of electrochemical cells for capacitive deionization (including electrochemical purification) and regeneration of electrodes is operated at alternate polarities during consecutive cycles. In other words, after each regeneration step operated at a given polarity in a deionization-regeneration cycle, the polarity of the deionization step in the next cycle is maintained. In one embodiment, two end electrodes are arranged one at each end of the battery, adjacent to end plates. An insulator layer is interposed between each end plate and the adjacent end electrode. Each end electrode includes a single sheet of conductive material having a high specific surface area and sorption capacity, preferably a sheet formed of carbon aerogel composite. The battery further includes a plurality of generally identical double-sided intermediate electrodes that are equidistally separated from each other, between the two end electrodes. As the electrolyte enters the battery of cells, it flows through a continuous open serpentine channel defined by the electrodes, substantially parallel to the surfaces of the electrodes. By polarizing the cells, ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the electrodes of each cell of the battery are saturated with the removed ions, the battery is regenerated electrically at a reversed polarity from that during the deionization step of the cycle, thus significantly minimizing secondary wastes.

Alternating-polarity operation for complete regeneration of electrochemical deionization system

DOEpatents

Tran, Tri D [Livermore, CA; Lenz, David J [Livermore, CA

2006-11-21

An electrically regeneratable battery of electrochemical cells for capacitive deionization (including electrochemical purification) and regeneration of electrodes is operated at alternate polarities during consecutive cycles. In other words, after each regeneration step operated at a given polarity in a deionization-regeneration cycle, the polarity of the deionization step in the next cycle is maintained. In one embodiment, two end electrodes are arranged one at each end of the battery, adjacent to end plates. An insulator layer is interposed between each end plate and the adjacent end electrode. Each end electrode includes a single sheet of conductive material having a high specific surface area and sorption capacity, preferably a sheet formed of carbon aerogel composite. The batter further includes a plurality of generally identical double-sided intermediate electrodes that are equidistally separated from each other, between the two end electrodes. As the electrolyte enters the battery of ells, t flows through a continuous open serpentine channel defined by the electrodes, substantially parallel to the surfaces of the electrodes. By polarizing the cells, ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the electrodes of each cell of the battery are saturated with the removed ions, the battery is regenerated electrically at a reversed polarity from that during the deionization step of the cycle, thus significantly minimizing secondary wastes.

Facile synthesis of graphene-wrapped honeycomb MnO2 nanospheres and their application in supercapacitors.

PubMed

Zhu, Jiayi; He, Junhui

2012-03-01

Graphene-wrapped MnO(2) nanocomposites were first fabricated by coassembly between honeycomb MnO(2) nanospheres and graphene sheets via electrostatic interaction. The materials were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and thermogravimetric analysis. The novel MnO(2)/graphene hybrid materials were used for investigation of electrochemical capacitive behaviors. The hybrid materials displayed enhanced capacitive performance (210 F/g at 0.5 A/g). Additionally, over 82.4% of the initial capacitance was retained after repeating the cyclic voltammetry test for 1000 cycles. The improved electrochemical performance might be attributed to the combination of the pesudocapacitance of MnO(2) nanospheres with the honeycomb-like "opened" structure and good electrical conductivity of graphene sheets. © 2012 American Chemical Society

Freestanding polyaniline nanorods grown on graphene for highly capacitive energy storage

NASA Astrophysics Data System (ADS)

Li, Zijiong; Qin, Zhen; Yang, Baocheng; Guo, Jian; Wang, Haiyan; Zhang, Weiyang; Lv, Xiaowei; Stack, Alison

2015-02-01

Freestanding polyaniline (PANI) nanorods grown in situ on microwave-expanded graphene oxide (MEGO) sheets were prepared through a facile solution method. The morphological characterization indicates that large quantity of free-standing PANI nanorods with average diameter of 50 nm were uniformly deposited onto the double sides of the MEGO nanosheets to form a sandwich structure. The hybrid of PANI/MEGO (GPANI) exhibit high specific surface area and high electrical conductivity, compared with pristine PANI nanorods. When evaluated as electrodes for supercapacitors, the GPANI demonstrate high specific capacitance of 628 F g-1 at a current density of 1.1 A g-1, high-rate performance, and excellent cycle stability compared to individual component. Such excellent electrochemical performance should be attributed to the combined double-layer capacitance and pseudo -capacitance mechanisms from the MEGO sheets and PANI nanorods.

Magnetic field line reconnection experiments. V - Current disruptions and double layers

NASA Technical Reports Server (NTRS)

Stenzel, R. L.; Gekelman, W.; Wild, N.

1983-01-01

An investigation is conducted of the stability of a large laboratory plasma current sheet, which has been generated in the process of magnetic field line reconnection, with respect to local current increases. Magnetic flux variations in regions remote from the current sheet generate an inductive voltage in the current loop that drops off inside the plasma in the form of a potential double layer, leading to particle acceleration with velocities much larger than those expected from the steady state electric fields in the plasma. A model for the mechanism of the current disruptions is formulated in which the potential structure leads to ion expulsion, creating a localized density drop. The associated current drop in an inductive circuit drives the potential structure, providing feedback for the disruptive instability. Similarities to, and differences from, magnetospheric substorm phenomena are noted.

Graphene: powder, flakes, ribbons, and sheets.

PubMed

James, Dustin K; Tour, James M

2013-10-15

Graphene's unique physical and electrical properties (high tensile strength, Young's modulus, electron mobility, and thermal conductivity) have led to its nickname of "super carbon." Graphene research involves the study of several different physical forms of the material: powders, flakes, ribbons, and sheets and others not yet named or imagined. Within those forms, graphene can include a single layer, two layers, or ≤10 sheets of sp² carbon atoms. The chemistry and applications available with graphene depend on both the physical form of the graphene and the number of layers in the material. Therefore the available permutations of graphene are numerous, and we will discuss a subset of this work, covering some of our research on the synthesis and use of many of the different physical and layered forms of graphene. Initially, we worked with commercially available graphite, with which we extended diazonium chemistry developed to functionalize single-walled carbon nanotubes to produce graphitic materials. These structures were soluble in common organic solvents and were better dispersed in composites. We developed an improved synthesis of graphene oxide (GO) and explored how the workup protocol for the synthesis of GO can change the electronic structure and chemical functionality of the GO product. We also developed a method to remove graphene layers one-by-one from flakes. These powders and sheets of GO can serve as fluid loss prevention additives in drilling fluids for the oil industry. Graphene nanoribbons (GNRs) combine small width with long length, producing valuable electronic and physical properties. We developed two complementary syntheses of GNRs from multiwalled carbon nanotubes: one simple oxidative method that produces GNRs with some defects and one reductive method that produces GNRs that are less defective and more electrically conductive. These GNRs can be used in low-loss, high permittivity composites, as conductive reinforcement coatings on Kevlar fibers and in the fabrication of large area transparent electrodes. Using solid carbon sources such as polymers, food, insects, and waste, we can grow monolayer and bilayer graphene directly on metal catalysts, and carbon-sources containing nitrogen can produce nitrogen-doped graphene. The resulting graphene can be transferred to other surfaces, such as metal grids, for potential use in transparent touch screens for applications in personal electronics and large area photovoltaic devices. Because the transfer of graphene from one surface to another can lead to defects, low yields, and higher costs, we have developed methods for growing graphene directly on the substrates of interest. We can also produce patterned graphene to make GNRs or graphane/graphene superlattices within a single sheet. These superlattices could have multiple functions for use in sensors and other devices. This Account only touches upon this burgeoning area of materials chemistry, and the field will continue to expand as researchers imagine new forms and applications of graphene.

The electrical properties of 60 keV zinc ions implanted into semi-insulating gallium arsenide

NASA Technical Reports Server (NTRS)

Littlejohn, M. A.; Anikara, R.

1972-01-01

The electrical behavior of zinc ions implanted into chromium-doped semiinsulating gallium arsenide was investigated by measurements of the sheet resistivity and Hall effect. Room temperature implantations were performed using fluence values from 10 to the 12th to 10 to the 15th power/sq cm at 60 keV. The samples were annealed for 30 minutes in a nitrogen atmosphere up to 800 C in steps of 200 C and the effect of this annealing on the Hall effect and sheet resistivity was studied at room temperature using the Van der Pauw technique. The temperature dependence of sheet resistivity and mobility was measured from liquid nitrogen temperature to room temperature. Finally, a measurement of the implanted profile was obtained using a layer removal technique combined with the Hall effect and sheet resistivity measurements.

The influence of assist gas on magnetic properties of electrotechnical steel sheets cut with laser

NASA Astrophysics Data System (ADS)

Gaworska-Koniarek, Dominika; Szubzda, Bronisław; Wilczyński, Wiesław; Drosik, Jerzy; Karaś, Kazimierz

2011-07-01

The paper presents the influence of assist gas (air and nitrogen) during laser cutting on magnetization, magnetic permeability and loss characteristics of non-oriented electrical steels. The research was made on an non-oriented M330-50A grade electrical steels by means of single sheet tester. In order to enhance the effect of cutting and the same degradation zone on magnetic properties, strips with different width were achieved. Measurements results indicate that application of air as assist gas has more destructive effect on magnetic properties of electrical steels than nitrogen one.

Modeling the electrical resistance of gold film conductors on uniaxially stretched elastomeric substrates

NASA Astrophysics Data System (ADS)

Cao, Wenzhe; Görrn, Patrick; Wagner, Sigurd

2011-05-01

The electrical resistance of gold film conductors on polydimethyl siloxane substrates at stages of uniaxial stretching is measured and modeled. The surface area of a gold conductor is assumed constant during stretching so that the exposed substrate takes up all strain. Sheet resistances are calculated from frames of scanning electron micrographs by numerically solving for the electrical potentials of all pixels in a frame. These sheet resistances agree sufficiently well with values measured on the same conductors to give credence to the model of a stretchable network of gold links defined by microcracks.

Gold nanoparticles deposited on glass: physicochemical characterization and cytocompatibility

PubMed Central

2013-01-01

Properties of gold films sputtered under different conditions onto borosilicate glass substrate were studied. Mean thickness of sputtered gold film was measured by gravimetry, and film contact angle was determined by goniometry. Surface morphology was examined by atomic force microscopy, and electrical sheet resistance was determined by two-point technique. The samples were seeded with rat vascular smooth muscle cells, and their adhesion and proliferation were studied. Gold depositions lead to dramatical changes in the surface morphology and roughness in comparison to pristine substrate. For sputtered gold structures, the rapid decline of the sheet resistance appears on structures deposited for the times above 100 s. The thickness of deposited gold nanoparticles/layer is an increasing function of sputtering time and current. AFM images prove the creation of separated gold islands in the initial deposition phase and a continuous gold coverage for longer deposition times. Gold deposition has a positive effect on the proliferation of vascular smooth muscle cells. Largest number of cells was observed on sample sputtered with gold for 20 s and at the discharge current of 40 mA. This sample exhibits lowest contact angle, low relative roughness, and only mild increase of electrical conductivity. PMID:23705782

Ohm's law for a current sheet

NASA Technical Reports Server (NTRS)

Lyons, L. R.; Speiser, T. W.

1985-01-01

The paper derives an Ohm's law for single-particle motion in a current sheet, where the magnetic field reverses in direction across the sheet. The result is considerably different from the resistive Ohm's law often used in MHD studies of the geomagnetic tail. Single-particle analysis is extended to obtain a self-consistency relation for a current sheet which agrees with previous results. The results are applicable to the concept of reconnection in that the electric field parallel to the current is obtained for a one-dimensional current sheet with constant normal magnetic field. Dissipated energy goes directly into accelerating particles within the current sheet.

Silanization of boron nitride nanosheets (BNNSs) through microfluidization and their use for producing thermally conductive and electrically insulating polymer nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seyhan, A.Tuğrul, E-mail: atseyhan@anadolu.edu.tr; Composite Materials Manufacturing Science Laboratory; Göncü, Yapıncak

Chemical exfoliation of boron nitride nanosheets (BNNSs) from large flakes of specially synthesized micro-sized hexagonal boron nitride (h-BN) ceramics was carried out through microfluidization. The surface of BNNSs obtained was then functionalized with vinyl-trimethoxy silane (VTS) coupling agent through microfluidization once again in an effort to make them compatible with organic materials, especially those including polymers. The morphology of BNNSs with and without silane treatment was then systematically characterized by conducting various different analytical techniques, including Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Bright field Transmission Electron Microscopy (BF-TEM), Contact angle analyzer (CAA), Particle size analyzer (PSA)more » and Fourier Transmission Infrared (FTIR) spectroscopy attached with attenuated total reflectance (ATR) module. As a result, the silane treatment was determined to be properly and successfully carried out and to give rise to the irregularity of large flakes of the BNNSs by folding back their free edges upon themselves, which in turn assists in inducing further exfoliation of the few-layered nanosheets. To gain more insight into the effectiveness of the surface functionalization, thermal conductivity of polypropylene (PP) nanocomposites containing different amounts (1 wt% and 5 wt%) of BNNSs with and without silane treatment was experimentally investigated. Regardless of the weight content, PP nanocomposites containing silanized BNNSs were found to exhibit high thermal conductivity compared to PP nanocomposites containing BNNSs without silane treatment. It was concluded that microfluidization possesses the robustness to provide a reliable product quality, whether in small or large quantities, in a very time effective manner, when it comes to first exfoliating two-dimensional inorganic materials into few layered sheets, and functionalizing the surface of these sheets afterwards to make it possible to utilize them as promising filler constituent in manufacturing thermally conductive and electrically insulating polymer nanocomposites that could be considered as whole or a part of a heat-releasing device.« less

Silanization of boron nitride nanosheets (BNNSs) through microfluidization and their use for producing thermally conductive and electrically insulating polymer nanocomposites

NASA Astrophysics Data System (ADS)

Seyhan, A. Tuğrul; Göncü, Yapıncak; Durukan, Oya; Akay, Atakan; Ay, Nuran

2017-05-01

Chemical exfoliation of boron nitride nanosheets (BNNSs) from large flakes of specially synthesized micro-sized hexagonal boron nitride (h-BN) ceramics was carried out through microfluidization. The surface of BNNSs obtained was then functionalized with vinyl-trimethoxy silane (VTS) coupling agent through microfluidization once again in an effort to make them compatible with organic materials, especially those including polymers. The morphology of BNNSs with and without silane treatment was then systematically characterized by conducting various different analytical techniques, including Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Bright field Transmission Electron Microscopy (BF-TEM), Contact angle analyzer (CAA), Particle size analyzer (PSA) and Fourier Transmission Infrared (FTIR) spectroscopy attached with attenuated total reflectance (ATR) module. As a result, the silane treatment was determined to be properly and successfully carried out and to give rise to the irregularity of large flakes of the BNNSs by folding back their free edges upon themselves, which in turn assists in inducing further exfoliation of the few-layered nanosheets. To gain more insight into the effectiveness of the surface functionalization, thermal conductivity of polypropylene (PP) nanocomposites containing different amounts (1 wt% and 5 wt%) of BNNSs with and without silane treatment was experimentally investigated. Regardless of the weight content, PP nanocomposites containing silanized BNNSs were found to exhibit high thermal conductivity compared to PP nanocomposites containing BNNSs without silane treatment. It was concluded that microfluidization possesses the robustness to provide a reliable product quality, whether in small or large quantities, in a very time effective manner, when it comes to first exfoliating two-dimensional inorganic materials into few layered sheets, and functionalizing the surface of these sheets afterwards to make it possible to utilize them as promising filler constituent in manufacturing thermally conductive and electrically insulating polymer nanocomposites that could be considered as whole or a part of a heat-releasing device.

Multifunctional surface modification of silk fabric via graphene oxide repeatedly coating and chemical reduction method

NASA Astrophysics Data System (ADS)

Cao, Jiliang; Wang, Chaoxia

2017-05-01

Multifunctional silk fabrics with electrical conductive, anti-ultraviolet and water repellent were successfully prepared by surface modification with graphene oxide (GO). The yellow-brown GO deposited on the surface of silk fabric was converted into graphitic black reduced graphene (RGO) by sodium hydrosulfite. The surface properties of silk fabrics were changed by repeatedly RGO coating process, which have been proved by SEM and XPS. The SEM results showed that the RGO sheets were successive form a continuously thin film on the surface of silk fabrics, and the deposition of GO or RGO also can be proved by XPS. The electrical conductivity was tested by electrical surface resistance value of the silk fabric, the surface resistance decreased with increasing of RGO surface modification times, and a low surface resistance value reached to 3.24 KΩ cm-1 after 9 times of modification, indicating the silk obtained excellent conductivity. The UPF value of one time GO modification silk fabric (silk-1RGO) was enhanced significantly to 24.45 in comparison to 10.40 of original silk. The contact angle of RGO coating silk samples was all above of 120°. The durability of RGO coated silk fabrics was tested by laundering. The electrical surface resistance of silk-4RGO (65.74 KΩ cm-1), silk-6RGO (15.54 KΩ cm-1) and silk-8RGO (3.86 KΩ cm-1) fabrics was up to 86.82, 22.30 and 6.57 KΩ cm-1 after 10 times of standard washing, respectively. The UPF value, contact angle and color differences of RGO modified silk fabric slightly changed before and after 10 times of standard washing. Therefore, the washing fastness of electric conduction, anti-ultraviolet and water repellent multifunctional silk fabrics was excellent.

Critical Evaluation of State-of-the-Art In Situ Thermal Treatment Technologies for DNAPL Source Zone Treatment

DTIC Science & Technology

2010-01-01

from steel pipe , copper plate for heating distinct zones and sheet pile. Sheet pile electrodes allow for quick installation with little to no drilling...as electrodes. Electrodes constructed using Thermal Remediation Services - Electrical Resistance Heating ER-0314 18 Appendix B steel pipe are...who authored state- of-the-art descriptions for the most common in-situ thermal technologies currently employed:  Electrical Resistance Heating

Exploration geophysics calculator programs for use on Hewlett-Packard models 67 and 97 programmable calculators

USGS Publications Warehouse

Campbell, David L.; Watts, Raymond D.

1978-01-01

Program listing, instructions, and example problems are given for 12 programs for the interpretation of geophysical data, for use on Hewlett-Packard models 67 and 97 programmable hand-held calculators. These are (1) gravity anomaly over 2D prism with = 9 vertices--Talwani method; (2) magnetic anomaly (?T, ?V, or ?H) over 2D prism with = 8 vertices?Talwani method; (3) total-field magnetic anomaly profile over thick sheet/thin dike; (4) single dipping seismic refractor--interpretation and design; (5) = 4 dipping seismic refractors--interpretation; (6) = 4 dipping seismic refractors?design; (7) vertical electrical sounding over = 10 horizontal layers--Schlumberger or Wenner forward calculation; (8) vertical electric sounding: Dar Zarrouk calculations; (9) magnetotelluric planewave apparent conductivity and phase angle over = 9 horizontal layers--forward calculation; (10) petrophysics: a.c. electrical parameters; (11) petrophysics: elastic constants; (12) digital convolution with = 10-1ength filter.

Thermal conductor for high-energy electrochemical cells

DOEpatents

Hoffman, Joseph A.; Domroese, Michael K.; Lindeman, David D.; Radewald, Vern E.; Rouillard, Roger; Trice, Jennifer L.

2000-01-01

A thermal conductor for use with an electrochemical energy storage device is disclosed. The thermal conductor is attached to one or both of the anode and cathode contacts of an electrochemical cell. A resilient portion of the conductor varies in height or position to maintain contact between the conductor and an adjacent wall structure of a containment vessel in response to relative movement between the conductor and the wall structure. The thermal conductor conducts current into and out of the electrochemical cell and conducts thermal energy between the electrochemical cell and thermally conductive and electrically resistive material disposed between the conductor and the wall structure. The thermal conductor may be fabricated to include a resilient portion having one of a substantially C-shaped, double C-shaped, Z-shaped, V-shaped, O-shaped, S-shaped, or finger-shaped cross-section. An elastomeric spring element may be configured so as to be captured by the resilient conductor for purposes of enhancing the functionality of the thermal conductor. The spring element may include a protrusion that provides electrical insulation between the spring conductor and a spring conductor of an adjacently disposed electrochemical cell in the presence of relative movement between the cells and the wall structure. The thermal conductor may also be fabricated from a sheet of electrically conductive material and affixed to the contacts of a number of electrochemical cells.

Optical mapping of conduction in early embryonic quail hearts with light-sheet microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ma, Pei; Gu, Shi; Wang, Yves T.; Jenkins, Michael W.; Rollins, Andrew M.

2016-03-01

Optical mapping (OM) using fluorescent voltage-sensitive dyes (VSD) to measure membrane potential is currently the most effective method for electrophysiology studies in early embryonic hearts due to its noninvasiveness and large field-of-view. Conventional OM acquires bright-field images, collecting signals that are integrated in depth and projected onto a 2D plane, not capturing the 3D structure of the sample. Early embryonic hearts, especially at looping stages, have a complicated, tubular geometry. Therefore, conventional OM cannot provide a full picture of the electrical conduction circumferentially around the heart, and may result in incomplete and inaccurate measurements. Here, we demonstrate OM of Hamburger and Hamilton stage 14 embryonic quail hearts using a new commercially-available VSD, Fluovolt, and depth sectioning using a custom built light-sheet microscopy system. Axial and lateral resolution of the system is 14µm and 8µm respectively. For OM imaging, the field-of-view was set to 900µm×900µm to cover the entire heart. 2D over time OM image sets at multiple cross-sections through the looping-stage heart were recorded. The shapes of both atrial and ventricular action potentials acquired were consistent with previous reports using conventional VSD (di-4-ANNEPS). With Fluovolt, signal-to-noise ratio (SNR) is improved significantly by a factor of 2-10 (compared with di-4-ANNEPS) enabling light-sheet OM, which intrinsically has lower SNR due to smaller sampling volumes. Electrophysiologic parameters are rate dependent. Optical pacing was successfully integrated into the system to ensure heart rate consistency. This will also enable accurately gated reconstruction of full four dimensional conduction maps and 3D conduction velocity measurements.

Light-extraction enhancement of GaN-based 395  nm flip-chip light-emitting diodes by an Al-doped ITO transparent conductive electrode.

PubMed

Xu, Jin; Zhang, Wei; Peng, Meng; Dai, Jiangnan; Chen, Changqing

2018-06-01

The distinct ultraviolet (UV) light absorption of indium tin oxide (ITO) limits the performance of GaN-based near-UV light-emitting diodes (LEDs). Herein, we report an Al-doped ITO with enhanced UV transmittance and low sheet resistance as the transparent conductive electrode for GaN-based 395 nm flip-chip near-UV LEDs. The thickness dependence of optical and electrical properties of Al-doped ITO films is investigated. The optimal Al-doped ITO film exhibited a transmittance of 93.2% at 395 nm and an average sheet resistance of 30.1  Ω/sq. Meanwhile, at an injection current of 300 mA, the forward voltage decreased from 3.14 to 3.11 V, and the light output power increased by 13% for the 395 nm near-UV flip-chip LEDs with the optimal Al-doped ITO over those with pure ITO. This Letter provides a simple and repeatable approach to further improve the light extraction efficiency of GaN-based near-UV LEDs.

Current-induced nonuniform enhancement of sheet resistance in A r+ -irradiated SrTi O3

NASA Astrophysics Data System (ADS)

Roy, Debangsu; Frenkel, Yiftach; Davidovitch, Sagi; Persky, Eylon; Haham, Noam; Gabay, Marc; Kalisky, Beena; Klein, Lior

2017-06-01

The sheet resistance Rs of A r+ irradiated SrTi O3 in patterns with a length scale of several microns increases significantly below ˜40 K in connection with driving currents exceeding a certain threshold. The initial lower Rs is recovered upon warming with accelerated recovery around 70 and 160 K. Scanning superconducting quantum interference device microscopy shows local irreversible changes in the spatial distribution of the current with a length scale of several microns. We attribute the observed nonuniform enhancement of Rs to the attraction of the charged single-oxygen and dioxygen vacancies by the crystallographic domain boundaries in SrTi O3 . The boundaries, which are nearly ferroelectric below 40 K, are polarized by the local electrical field associated with the driven current and the clustered vacancies which suppress conductivity in their vicinity and yield a noticeable enhancement in the device resistance when the current path width is on the order of the boundary extension. The temperatures of accelerated conductivity recovery are associated with the energy barriers for the diffusion of the two types of vacancies.

REACH. Electricity Units. Secondary.

ERIC Educational Resources Information Center

Smith, Gene; Sappe, Hoyt

As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of electricity. The instructional units focus on electricity fundamentals and electric motors. Each unit follows a typical format that includes a unit sheet,…

[Surgical Regeneration Therapy Using Myoblast Sheets for Severe Heart Failure].

PubMed

Sawa, Yoshiki

2017-01-01

Heart failure is a life-threatening disorder worldwide, and the current end-stage therapies for severe heart failure are replacement therapies such as ventricular-assist devices and heart transplantation. Although these therapies have been reported to be useful, there are many issues in terms of the durability, complications, limited donors, adverse effect of continuous administration of immunosuppressive agents, and high costs involved. Recently, regenerative therapy based on genetic, cellular, or tissue engineering techniques has gained attention as a new therapy to overcome the challenges encountered in transplantation medicine. We focused on skeletal myoblasts as the source of progenitor cells for autologous cell transplantation and the cell-sheet technique for site-specific implantation. In vitro studies have reported that myoblast sheets secrete cytoprotective and angiogenic cytokines such as hepatocyte growth factor (HGF). Additionally, in vivo studies using large and small animal models of heart failure, we have shown that myoblast sheets could improve diastolic and systolic performance and enhance angiogenesis and antifibrosis as well as the expression of several cytokines including HGF and vascular endothelial growth factor(VEGF) in the tissues at the transplanted site. Based on the results of these studies, we performed clinical trials using autologous myoblast sheets in ischemic cardiomyopathy (ICM) and dilated cardiomyopathy patients. Some patients showed left ventricular reverse remodeling and improved symptoms and exercise tolerance. Recently, multiple medical institutions including our institution successfully conducted an exploratory, uncontrolled, open-label phase II study in subjects with ICM to validate the efficacy and safety of autologous myoblast sheets. Moreover, as a novel cell source for regenerative medicine, our recent studies demonstrated that induced pluripotent stem cell-derived cardiomyocyte sheets showed electrical and microstructural homogeneity with heart tissue in vitro and in vivo, thus establishing proof of concept in small and large animal models of heart failure.

Effect of carbon-sulphur bond in a sulphur/dehydrogenated polyacrylonitrile/reduced graphene oxide composite cathode for lithium-sulphur batteries

NASA Astrophysics Data System (ADS)

Konarov, Aishuak; Bakenov, Zhumabay; Yashiro, Hitoshi; Sun, Yang-Kook; Myung, Seung-Taek

2017-07-01

A S/DPAN (dehydrogenated polyacrylonitrile) composite shows promising electrode performances as a cathode material for Li-S batteries though its electric conductivity is insufficient for high rate tests. In an attempt to enhance the electric conductivity, the S/DPAN composite is attached on reduced graphene oxide (rGO) sheets via self-assembling modification. As a result, the conductivity improves to ∼10-4 S cm-1, and the S/DPAN/rGO composite thereby delivers approximately 90% of the theoretical capacity of sulphur at a rate of 0.2C (0.34 A g-1) over 700 mAh (g-S)-1 even at 2C (3.4 A g-1). We first report on the Csbnd S bond between sulphur and DPAN in a composite that maintains the bond even after an extensive cycling test, as confirmed by time-of-flight secondary-ion mass spectroscopy (ToF-SIMS). These synergistic effects enable facile electron transport such that the S/DPAN/rGO composite electrode is able to maintain superior electrode performances.

Voltage-induced reduction of graphene oxide

NASA Astrophysics Data System (ADS)

Faucett, Austin C.

Graphene Oxide (GO) is being widely researched as a precursor for the mass production of graphene, and as a versatile material in its own right for flexible electronics, chemical sensors, and energy harvesting applications. Reduction of GO, an electrically insulating material, into reduced graphene oxide (rGO) restores electrical conductivity via removal of oxygen-containing functional groups. Here, a reduction method using an applied electrical bias, known as voltage-induced reduction, is explored. Voltage-induced reduction can be performed under ambient conditions and avoids the use of hazardous chemicals or high temperatures common with standard methods, but little is known about the reduction mechanisms and the quality of rGO produced with this method. This work performs extensive structural and electrical characterization of voltage-reduced GO (V-rGO) and shows that it is competitive with standard methods. Beyond its potential use as a facile and eco-friendly processing approach, V-rGO reduction also offers record high-resolution patterning capabilities. In this work, the spatial resolution limits of voltage-induced reduction, performed using a conductive atomic force microscope probe, are explored. It is shown that arbitrary V-rGO conductive features can be patterned into insulating GO with nanoscale resolution. The localization of voltage-induced reduction to length scales < 10 nm allows studies of reduction reaction kinetics, using electrical current obtained in-situ, with statistical robustness. Methods for patterning V-rGO nanoribbons are then developed. After presenting sub-10nm patterning of V-rGO nanoribbons in GO single sheets and films, the performance of V-rGO nanoribbon field effect transistors (FETs) are demonstrated. Preliminary measurements show an increase in electrical current on/off ratios as compared to large-area rGO FETs, indicating transport gap modulation that is possibly due to quantum confinement effects.

Electric currents and voltage drops along auroral field lines

NASA Technical Reports Server (NTRS)

Stern, D. P.

1983-01-01

An assessment is presented of the current state of knowledge concerning Birkeland currents and the parallel electric field, with discussions focusing on the Birkeland primary region 1 sheets, the region 2 sheets which parallel them and appear to close in the partial ring current, the cusp currents (which may be correlated with the interplanetary B(y) component), and the Harang filament. The energy required by the parallel electric field and the associated particle acceleration processes appears to be derived from the Birkeland currents, for which evidence is adduced from particles, inverted V spectra, rising ion beams and expanded loss cones. Conics may on the other hand signify acceleration by electrostatic ion cyclotron waves associated with beams accelerated by the parallel electric field.

Current Sheet Formation in a Conical Theta Pinch Faraday Accelerator with Radio-frequency Assisted Discharge

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Hallock, Ashley K.; Choueiri, Edgar Y.

2008-01-01

Data from an inductive conical theta pinch accelerator are presented to gain insight into the process of inductive current sheet formation in the presence of a preionized background gas produced by a steady-state RF-discharge. The presence of a preionized plasma has been previously shown to allow for current sheet formation at lower discharge voltages and energies than those found in other pulsed inductive accelerator concepts, leading to greater accelerator efficiencies at lower power levels. Time-resolved magnetic probe measurements are obtained for different background pressures and pulse energies to characterize the effects of these parameters on current sheet formation. Indices are defined that describe time-resolved current sheet characteristics, such as the total current owing in the current sheet, the time-integrated total current ('strength'), and current sheet velocity. It is found that for a given electric field strength, maximums in total current, strength, and velocity occur for one particular background pressure. At other pressures, these current sheet indices are considerably smaller. The trends observed in these indices are explained in terms of the principles behind Townsend breakdown that lead to a dependence on the ratio of the electric field to the background pressure. Time-integrated photographic data are also obtained at the same experimental conditions, and qualitatively they compare quite favorably with the time-resolved magnetic field data.

Asheville, North Carolina: Reducing Electricity Demand through Building Programs & Policies (City Energy: From Data to Decisions)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Office of Strategic Programs, Strategic Priorities and Impact Analysis Team

This fact sheet "Asheville, North Carolina: Reducing Electricity Demand through Building Programs & Policies" explains how the City of Asheville used data from the U.S. Department of Energy's Cities Leading through Energy Analysis and Planning (Cities-LEAP) and the State and Local Energy Data (SLED) programs to inform its city energy planning. It is one of ten fact sheets in the "City Energy: From Data to Decisions" series.

Lafayette, Colorado: Using Energy Data for Electric Vehicle Infrastructure Planning (City Energy: From Data to Decisions)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Office of Strategic Programs, Strategic Priorities and Impact Analysis Team

This fact sheet "Lafayette, Colorado: Using Energy Data for Electric Vehicle Infrastructure Planning" explains how the City of Lafayette used data from the U.S. Department of Energy's Cities Leading through Energy Analysis and Planning (Cities-LEAP) and the State and Local Energy Data (SLED) programs to inform its city energy planning. It is one of ten fact sheets in the "City Energy: From Data to Decisions" series.

Nanotube Aerogel Sheet Flutter for Actuation, Power Generation, and Infrasound Detection

PubMed Central

Kang, Tae June; Kim, Taewoo; Jang, Eui Yun; Im, Hyeongwook; Lepro-Chavez, Xavier; Ovalle-Robles, Raquel; Oh, Jiyoung; Kozlov, Mikhail E.; Baughman, Ray H.; Lee, Hong H.; Kim, Yong Hyup

2014-01-01

Electromagnetic induction (EMI) is a mechanism of classical physics that can be utilized to convert mechanical energy to electrical energy or electrical to mechanical energy. This mechanism has not been exploited fully because of lack of a material with a sufficiently low force constant. We here show that carbon nanotube (CNT) aerogel sheets can exploit EMI to provide mechanical actuation at very low applied voltages, to harvest mechanical energy from small air pressure fluctuations, and to detect infrasound at inaudible frequencies below 20 Hz. Using conformal deposition of 100 nm thick aluminum coatings on the nanotubes in the sheets, mechanical actuation can be obtained by applying millivolts, as compared with the thousand volts needed to achieve giant-stroke electrostatic actuation of carbon nanotube aerogel sheets. Device simplicity and performance suggest possible applications as an energy harvester of low energy air fluctuations and as a sensor for infrasound frequencies. PMID:25130708

Nanotube aerogel sheet flutter for actuation, power generation, and infrasound detection.

PubMed

Kang, Tae June; Kim, Taewoo; Jang, Eui Yun; Im, Hyeongwook; Lepro-Chavez, Xavier; Ovalle-Robles, Raquel; Oh, Jiyoung; Kozlov, Mikhail E; Baughman, Ray H; Lee, Hong H; Kim, Yong Hyup

2014-08-18

Electromagnetic induction (EMI) is a mechanism of classical physics that can be utilized to convert mechanical energy to electrical energy or electrical to mechanical energy. This mechanism has not been exploited fully because of lack of a material with a sufficiently low force constant. We here show that carbon nanotube (CNT) aerogel sheets can exploit EMI to provide mechanical actuation at very low applied voltages, to harvest mechanical energy from small air pressure fluctuations, and to detect infrasound at inaudible frequencies below 20 Hz. Using conformal deposition of 100 nm thick aluminum coatings on the nanotubes in the sheets, mechanical actuation can be obtained by applying millivolts, as compared with the thousand volts needed to achieve giant-stroke electrostatic actuation of carbon nanotube aerogel sheets. Device simplicity and performance suggest possible applications as an energy harvester of low energy air fluctuations and as a sensor for infrasound frequencies.

Thermal conductivity of freestanding single wall carbon nanotube sheet by Raman spectroscopy.

PubMed

Sahoo, Satyaprakash; Chitturi, Venkateswara Rao; Agarwal, Radhe; Jiang, Jin-Wu; Katiyar, Ram S

2014-11-26

Thermal properties of single wall carbon nanotube sheets (SWCNT-sheets) are of significant importance in the area of thermal management, as an isolated SWCNT possesses high thermal conductivity of the value about 3000 W m(-1) K(-1). Here we report an indirect method of estimating the thermal conductivity of a nanometer thick suspended SWCNT-sheet by employing the Raman scattering technique. Tube diameter size is examined by the transmissions electron microscopy study. The Raman analysis of the radial breathing modes predicts narrow diameter size distribution with achiral (armchair) symmetry of the constituent SWCNTs. From the first order temperature coefficient of the A1g mode of the G band along with the laser power dependent frequency shifting of this mode, the thermal conductivity of the suspended SWCNT-sheet is estimated to be about ∼18.3 W m(-1) K(-1). Our theoretical study shows that the thermal conductivity of the SWCNT-sheet has contributions simultaneously from the intratube and intertube thermal transport. The intertube thermal conductivity (with contributions from the van der Waals interaction) is merely around 0.7 W m(-1) K(-1), which is three orders smaller than the intratube thermal conductivity, leading to an abrupt decrease in the thermal conductivity of the SWCNT-sheet as compared to the reported value for isolated SWCNT.

Model of large volumetric capacitance in graphene supercapacitors based on ion clustering

NASA Astrophysics Data System (ADS)

Skinner, Brian; Fogler, M. M.; Shklovskii, B. I.

2011-12-01

Electric double-layer supercapacitors (SCs) are promising devices for high-power energy storage based on the reversible absorption of ions into porous conducting electrodes. Graphene is a particularly good candidate for the electrode material in SCs due to its high conductivity and large surface area. In this paper, we consider SC electrodes made from a stack of graphene sheets with randomly inserted spacer molecules. We show that the large volumetric capacitances C≳100F/cm3 observed experimentally can be understood as a result of collective intercalation of ions into the graphene stack and the accompanying nonlinear screening by graphene electrons that renormalizes the charge of the ion clusters.

A model of large volumetric capacitance in graphene supercapacitors based on ion clustering

NASA Astrophysics Data System (ADS)

Skinner, Brian; Fogler, Michael; Shklovskii, Boris

2012-02-01

Electric double layer supercapacitors are promising devices for high-power energy storage based on the reversible absorption of ions into porous, conducting electrodes. Graphene is a particularly good candidate for the electrode material in supercapacitors due to its high conductivity and large surface area. In this paper we consider supercapacitor electrodes made from a stack of graphene sheets with randomly-inserted ``spacer" molecules. We show that the large volumetric capacitances C > 100 F/cm^3 observed experimentally can be understood as a result of collective intercalation of ions into the graphene stack and the accompanying nonlinear screening by graphene electrons that renormalizes the charge of the ion clusters.

Propagation of large-amplitude waves on dielectric liquid sheets in a tangential electric field: exact solutions in three-dimensional geometry.

PubMed

Zubarev, Nikolay M; Zubareva, Olga V

2010-10-01

Nonlinear waves on sheets of dielectric liquid in the presence of an external tangential electric field are studied theoretically. It is shown that waves of arbitrary shape in three-dimensional geometry can propagate along (or against) the electric field direction without distortion, i.e., the equations of motion admit a wide class of exact traveling wave solutions. This unusual situation occurs for nonconducting ideal liquids with high dielectric constants in the case of a sufficiently strong field strength. Governing equations for evolution of plane symmetric waves on fluid sheets are derived using conformal variables. A dispersion relation for the evolution of small perturbations of the traveling wave solutions is obtained. It follows from this relation that, regardless of the wave shape, the amplitudes of small-scale perturbations do not increase with time and, hence, the traveling waves are stable. We also study the interaction of counterpropagating symmetric waves with small but finite amplitudes. The corresponding solution of the equations of motion describes the nonlinear superposition of the oppositely directed waves. The results obtained are applicable for the description of long waves on fluid sheets in a horizontal magnetic field.

Highly Electrically Conducting Glass-Graphene Nanoplatelets Hybrid Coatings.

PubMed

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

2015-08-19

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

Natural graphene microsheets/sulfur as Li-S battery cathode towards >99% coulombic efficiency of long cycles

NASA Astrophysics Data System (ADS)

Zhang, Yan; Duan, Xiaoyong; Wang, Jie; Wang, Congwei; Wang, Junying; Wang, Jianlong; Wang, Junzhong

2018-02-01

Lithium-sulfur battery receives intense attention owing to its high theoretical energy density. However, poor electrical conductivity of sulfur and poor cycle stability of the battery hinder its application. Here, we report that graphene microsheets prepared from microcrystalline graphite minerals by an electrochemical & mechanical approach work as a special conductive support to load sulfur as the cathode of lithium-sulfur battery. The graphene microsheets have the features of excellent conductivity and low defect, small sheet sizes of <1 μm2 and ≤6 atomic layers as well as natural silicate residue covered. Li-S batteries of graphene microsheets/S as cathode exhibit long-term cyclability and high coulombic efficiency. At 1 C for 2000 cycles, average coulombic efficiency of 99.7% is reached.

75 FR 17404 - Combined Notice of Filings # 1

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-06

..., 2010. Take notice that the Commission received the following electric rate filings: Docket Numbers: ER10-547-001. Applicants: Golden Spread Electric Cooperative, Inc. Description: Golden Spread Electric... Revised Sheet 7 et al. to FERC Electric Tariff, Fifth Revised Volume 1 to be effective 3/31/10. Filed Date...

Static current-sheet models of quiescent prominences

NASA Technical Reports Server (NTRS)

Wu, F.; Low, B. C.

1986-01-01

A particular class of theoretical models idealize the prominence to be a discrete flat electric-current sheet suspended vertically in a potential magnetic field. The weight of the prominence is supported by the Lorentz force in the current sheet. These models can be extended to have curved electric-current sheets and to vary three-dimensionally. The equation for force balance is 1 over 4 pi (del times B) times Bdel p- p9 z=zero. Using Cartesian coordinates we take, for simplicity, a uniform gravity with constant acceleration g in the direction -z. If we are interested not in the detailed internal structure of the prominence, but in the global magnetic configuration around the prominence, we may take prominence plasma to be cold. Consideration is given to how such equilibrium states can be constructed. To simplify the mathematical problem, suppose there is no electric current in the atmosphere except for the discrete currents in the cold prominence sheet. Let us take the plane z =0 to be the base of the atmosphere and restrict our attention to the domain z greater than 0. The task we have is to solve for a magnetic field which is everywhere potential except on some free surface S, subject to suit able to boundary conditions. The surface S is determined by requiring that it possesses a discrete electric current density such that the Lorentz force on it is everywhere vertically upward to balance the weight of the material m(S). Since the magnetic field is potential in the external atmosphere, the latter is decoupled from the magnetic field and its plane parallel hydrostatic pressure and density can be prescribed.

Static current-sheet models of quiescent prominences

NASA Astrophysics Data System (ADS)

Wu, F.; Low, B. C.

1986-12-01

A particular class of theoretical models idealize the prominence to be a discrete flat electric-current sheet suspended vertically in a potential magnetic field. The weight of the prominence is supported by the Lorentz force in the current sheet. These models can be extended to have curved electric-current sheets and to vary three-dimensionally. The equation for force balance is 1 over 4 pi (del times B) times Bdel p- p9 z=zero. Using Cartesian coordinates we take, for simplicity, a uniform gravity with constant acceleration g in the direction -z. If we are interested not in the detailed internal structure of the prominence, but in the global magnetic configuration around the prominence, we may take prominence plasma to be cold. Consideration is given to how such equilibrium states can be constructed. To simplify the mathematical problem, suppose there is no electric current in the atmosphere except for the discrete currents in the cold prominence sheet. Let us take the plane z =0 to be the base of the atmosphere and restrict our attention to the domain z greater than 0. The task we have is to solve for a magnetic field which is everywhere potential except on some free surface S, subject to suit able to boundary conditions. The surface S is determined by requiring that it possesses a discrete electric current density such that the Lorentz force on it is everywhere vertically upward to balance the weight of the material m(S). Since the magnetic field is potential in the external atmosphere, the latter is decoupled from the magnetic field and its plane parallel hydrostatic pressure and density can be prescribed.

Particle and field characteristics of the high-latitude plasma sheet boundary layer

NASA Technical Reports Server (NTRS)

Parks, G. K.; Mccarthy, M.; Fitzenreiter, R. J.; Ogilvie, K. W.; Etcheto, J.; Anderson, K. A.; Lin, R. P.; Anderson, R. R.; Eastman, T. E.; Frank, L. A.

1984-01-01

Particle and field data obtained by eight ISEE spacecraft experiments are used to define more precisely the characteristics of the high-latitude boundary region of the plasma sheet. A region immediately adjacent to the high-latitude plasma sheet boundary has particle and field characteristics distinctly different from those observed in the lobe and deeper in the central plasma sheet. Electrons over a broad energy interval are 'field-aligned' and bidirectional, whereas in the plasma sheet the distributions are more isotropic. The region supports intense ion flows, large-amplitude electric fields, and enhanced broad-band electrostatic noise.

Energization of the Ring Current through Convection of Substorm Enhancements of the Plasma Sheet Source.

NASA Astrophysics Data System (ADS)

Menz, A.; Kistler, L. M.; Mouikis, C.; Spence, H. E.; Henderson, M. G.; Matsui, H.

2017-12-01

It has been shown that electric field strength and night-side plasma sheet density are the two best predictors of the adiabatic energy gain of the ring current during geomagnetic storms (Liemohn and Khazanov, 2005). While H+ dominates the ring current during quiet times, O+ can contribute substantially during geomagnetic storms. Substorm activity provides a mechanism to enhance the energy density of O+ in the plasma sheet during geomagnetic storms, which is then convected adiabatically into the inner-magnetosphere. Using the Van Allen Probes data in the the plasma sheet source region (defined as L>5.5 during storms) and the inner magnetosphere, along with LANL-GEO data to identify substorm injection times, we show that adiabatic convection of O+ enhancements in the source region can explain the observed enhancements in the inner magnetosphere. We use the UNH-IMEF electric field model to calculate drift times from the source region to the inner magnetosphere to test whether enhancements in the inner-magnetosphere can be explained by dipolarization driven enhancements in the plasma sheet source hours before.

Ultrahigh-performance transparent conductive films of carbon-welded isolated single-wall carbon nanotubes

PubMed Central

Chen, Mao-Lin; Wang, Bing-Wei; Tang, Dai-Ming; Jin, Qun; Guo, Qing-Xun; Zhang, Ding-Dong; Du, Jin-Hong; Tai, Kai-Ping; Tan, Jun; Kauppinen, Esko I.

2018-01-01

Single-wall carbon nanotubes (SWCNTs) are ideal for fabricating transparent conductive films because of their small diameter, good optical and electrical properties, and excellent flexibility. However, a high intertube Schottky junction resistance, together with the existence of aggregated bundles of SWCNTs, leads to a degraded optoelectronic performance of the films. We report a network of isolated SWCNTs prepared by an injection floating catalyst chemical vapor deposition method, in which crossed SWCNTs are welded together by graphitic carbon. Pristine SWCNT films show a record low sheet resistance of 41 ohm □−1 at 90% transmittance for 550-nm light. After HNO3 treatment, the sheet resistance further decreases to 25 ohm □−1. Organic light-emitting diodes using this SWCNT film as anodes demonstrate a low turn-on voltage of 2.5 V, a high current efficiency of 75 cd A−1, and excellent flexibility. Investigation of isolated SWCNT-based field-effect transistors shows that the carbon-welded joints convert the Schottky contacts between metallic and semiconducting SWCNTs into near-ohmic ones, which significantly improves the conductivity of the transparent SWCNT network. Our work provides a new avenue of assembling individual SWCNTs into macroscopic thin films, which demonstrate great potential for use as transparent electrodes in various flexible electronics. PMID:29736413

Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

PubMed

Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

2017-07-01

Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modelling heat conduction in polycrystalline hexagonal boron-nitride films

PubMed Central

Mortazavi, Bohayra; Pereira, Luiz Felipe C.; Jiang, Jin-Wu; Rabczuk, Timon

2015-01-01

We conducted extensive molecular dynamics simulations to investigate the thermal conductivity of polycrystalline hexagonal boron-nitride (h-BN) films. To this aim, we constructed large atomistic models of polycrystalline h-BN sheets with random and uniform grain configuration. By performing equilibrium molecular dynamics (EMD) simulations, we investigated the influence of the average grain size on the thermal conductivity of polycrystalline h-BN films at various temperatures. Using the EMD results, we constructed finite element models of polycrystalline h-BN sheets to probe the thermal conductivity of samples with larger grain sizes. Our multiscale investigations not only provide a general viewpoint regarding the heat conduction in h-BN films but also propose that polycrystalline h-BN sheets present high thermal conductivity comparable to monocrystalline sheets. PMID:26286820

5. PHOTOCOPY OF DRAWING (1975 ELECTRICAL DRAWING BY THE STRATEGIC ...

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

5. PHOTOCOPY OF DRAWING (1975 ELECTRICAL DRAWING BY THE STRATEGIC AIR COMMAND, USAF) ELECTRICAL PLANS FOR BUILDING 768, SHEET 7 OF 8 - Vandenberg Air Force Base, Space Launch Complex 3, Entry Control Point, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

ELECTRICAL AND ELECTRONIC INDUSTRIAL CONTROL. BASIC ELECTRICITY, UNIT 3, ASSIGNMENTS.

ERIC Educational Resources Information Center

SUTTON, MACK C.

THIS GUIDE IS FOR INDIVIDUAL STUDENT USE IN STUDYING BASIC ELECTRICAL FUNDAMENTALS IN ELECTRICAL-ELECTRONIC PROGRAMS. IT WAS DEVELOPED BY AN INSTRUCTIONAL MATERIALS SPECIALIST AND ADVISERS. THE COURSE OBJECTIVE IS TO DEVELOP AN UNDERSTANDING OF DIRECT CURRENT FUNDAMENTALS. EACH OF THE 10 ASSIGNMENT SHEETS PROVIDES THE LESSON SUBJECT, PURPOSE,…

ELECTRICAL AND ELECTRONIC INDUSTRIAL CONTROL. BASIC ELECTRICITY, UNIT 2, ASSIGNMENTS.

ERIC Educational Resources Information Center

SUTTON, MACK C.

THIS GUIDE IS FOR INDIVIDUAL STUDENT USE IN STUDYING BASIC ELECTRICAL FUNDAMENTALS IN ELECTRICAL-ELECTRONIC PROGRAMS. IT WAS DEVELOPED BY AN INSTRUCTIONAL MATERIALS SPECIALIST AND ADVISERS. THE COURSE OBJECTIVE IS TO DEVELOP AN UNDERSTANDING OF DIRECT CURRENT FUNDAMENTALS. EACH OF THE 15 ASSIGNMENT SHEETS PROVIDES THE LESSON SUBJECT, PURPOSE,…

Multi-point Measurements of Relativistic Electrons in the Magnetosphere

NASA Astrophysics Data System (ADS)

Li, X.; Selesnick, R.; Baker, D. N.; Blake, J. B.; Schiller, Q.; Blum, L. W.; Zhao, H.; Jaynes, A. N.; Kanekal, S.

2014-12-01

We take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer on the four Cluster spacecraft. The calibrated observations of the three spectrometers are used to determine the proton and electron velocity moments. The velocity moments can be used to estimate the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. As the measurement techniques are so different, it is quite plausible that when two different measurements yield the same DC electric field, it is the correct field. All five measurements of the DC electric field are usually not simultaneously available, especially on Cluster 2 where CODIF and HIA are not operational, or on Cluster 4 where EDI is off. In this presentation we investigate DC electric field in various transient plasma sheet events such as dipolarization events and BBF's and how the five measurements agree or disagree. There are plenty of important issues that are considered, e.g., (1) what kind of DC electric fields exist in such events and what are their spatial scales, (2) do electrons and ions perform ExB drift motions in these events, and (3) how well the instruments have been calibrated.

Formation of Dawn-Dusk Asymmetry in Earth's Magnetotail Thin Current Sheet: A Three-Dimensional Particle-In-Cell Simulation

NASA Astrophysics Data System (ADS)

Lu, San; Pritchett, P. L.; Angelopoulos, V.; Artemyev, A. V.

2018-04-01

Using a three-dimensional particle-in-cell simulation, we investigate the formation of dawn-dusk asymmetry in Earth's magnetotail. The magnetotail current sheet is compressed by an external driving electric field down to a thickness on the order of ion kinetic scales. In the resultant thin current sheet (TCS) where the magnetic field line curvature radius is much smaller than ion gyroradius, a significant portion of the ions becomes unmagnetized and decoupled from the magnetized electrons, giving rise to a Hall electric field Ez and an additional cross-tail current jy caused by the unmagnetized ions being unable to comove with the electrons in the Hall electric field. The Hall electric field transports via E × B drift magnetic flux and magnetized plasma dawnward, causing a reduction of the current sheet thickness and the normal magnetic field Bz on the duskside. This leads to an even stronger Hall effect (stronger jy and Ez) in the duskside TCS. Thus, due to the internal kinetic effects in the TCS, namely, the Hall effect and the associated dawnward E × B drift, the magnetotail dawn-dusk asymmetry forms in a short time without any global, long-term effects. The duskside preference of reconnection and associated dynamic phenomena (such as substorm onsets, dipolarizing flux bundles, fast flows, energetic particle injections, and flux ropes), which has been pervasively observed by spacecraft in the past 20 years, can thus be explained as a consequence of this TCS asymmetry.

Novel transparent conductor with enhanced conductivity: hybrid of silver nanowires and dual-doped graphene

NASA Astrophysics Data System (ADS)

Sohn, Hiesang; Woo, Yun Sung; Shin, Weonho; Yun, Dong-Jin; Lee, Taek; Kim, Felix Sunjoo; Hwang, Jinyoung

2017-10-01

We present hybrid transparent conducting films based on silver nanowires (Ag NWs) and doped graphene through novel dual co-doping method by applying various dopants (HNO3 or Au for p-doping and N2H4 for n-doping) on top and bottom sides of graphene. We systematically investigated the effect of dual-doping on their surface as well as electrical and optical properties of graphene and Ag NW/graphene hybrid films through the combination study with various dopant types (p/p, p/n, n/p, and n/n). We found that the p/p-type dual-doped (p-type dopant: HNO3) graphene and its hybrid formation with Ag NWs appeared to be the most effective in enhancing the electrical properties of conductor (doped graphene with ΔR/R0 = 84% and Ag NW/doped graphene hybrid with ΔR/R0 = 62%), demonstrating doped monolayer graphene with high optical transmittance (TT = 97.4%), and sheet resistance (Rs = 188 Ω/sq.). We also note that dual-doping improved such electrical properties without any significant debilitation of optical transparency of conductors (doped graphene with ΔTT = 0.1% and Ag NW/doped graphene hybrid with ΔTT = 0.4%). In addition, the enhanced conductivity of p-type dual-doped graphene allows a hybrid system to form co-percolating network in which Ag NWs can form a secondary conductive path at grain boundaries of polycrystalline graphene.

8. PHOTOCOPY OF DRAWING (1975 ELECTRICAL DRAWING BY THE RALPH ...

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

8. PHOTOCOPY OF DRAWING (1975 ELECTRICAL DRAWING BY THE RALPH M. PARSONS COMPANY) ELECTRICAL PLAN AND DETAILS FOR BUILDING 762-A, SHEET E4 - Vandenberg Air Force Base, Space Launch Complex 3, Technical Support Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

160. Photocopy of drawing (1967 electrical drawing by Koebig & ...

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

160. Photocopy of drawing (1967 electrical drawing by Koebig & Koebig, Inc.) MST MODIFICATION AND REFURBISHMENT; ELECTRICAL MODIFICATIONS OF LAUNCH DECK, SHEET E-3 - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

Electrical conductivity of oxidized-graphenic nanoplatelets obtained from bamboo: effect of the oxygen content

NASA Astrophysics Data System (ADS)

Gross, K.; Prías Barragán, J. J.; Sangiao, S.; De Teresa, J. M.; Lajaunie, L.; Arenal, R.; Ariza Calderón, H.; Prieto, P.

2016-09-01

The large-scale production of graphene and reduced-graphene oxide (rGO) requires low-cost and eco-friendly synthesis methods. We employed a new, simple, cost-effective pyrolytic method to synthetize oxidized-graphenic nanoplatelets (OGNP) using bamboo pyroligneous acid (BPA) as a source. Thorough analyses via high-resolution transmission electron microscopy and electron energy-loss spectroscopy provides a complete structural and chemical description at the local scale of these samples. In particular, we found that at the highest carbonization temperature the OGNP-BPA are mainly in a sp2 bonding configuration (sp2 fraction of 87%). To determine the electrical properties of single nanoplatelets, these were contacted by Pt nanowires deposited through focused-ion-beam-induced deposition techniques. Increased conductivity by two orders of magnitude is observed as oxygen content decreases from 17% to 5%, reaching a value of 2.3 × 103 S m-1 at the lowest oxygen content. Temperature-dependent conductivity reveals a semiconductor transport behavior, described by the Mott three-dimensional variable range hopping mechanism. From the localization length, we estimate a band-gap value of 0.22(2) eV for an oxygen content of 5%. This investigation demonstrates the great potential of the OGNP-BPA for technological applications, given that their structural and electrical behavior is similar to the highly reduced rGO sheets obtained by more sophisticated conventional synthesis methods.

Lithium monosilicide (LiSi), a low-dimensional silicon-based material prepared by high pressure synthesis: NMR and vibrational spectroscopy and electrical properties characterization

NASA Astrophysics Data System (ADS)

Stearns, Linda A.; Gryko, Jan; Diefenbacher, Jason; Ramachandran, Ganesh K.; McMillan, Paul F.

2003-06-01

Lithium monosilicide (LiSi) was formed at high pressures and high temperatures (1.0-2.5 GPa and 500-700°C) in a piston-cylinder apparatus. This compound was previously shown to have an unusual structure based on 3-fold coordinated silicon atoms arranged into interpenetrating sheets. In the present investigation, lowered synthesis pressures permitted recovery of large (150-200 mg) quantities of sample for structural studies via NMR spectroscopy ( 29Si and 7Li), Raman spectroscopy and electrical conductivity measurements. The 29Si chemical shift occurs at -106.5 ppm, intermediate between SiH 4 and Si(Si(CH 3) 3) 4, but lies off the trend established by the other alkali monosilicides (NaSi, KSi, RbSi, CsSi), that contain isolated Si 44- anions. Raman spectra show a strong peak at 508 cm -1 due to symmetric Si-Si stretching vibrations, at lower frequency than for tetrahedrally coordinated Si frameworks, due to the longer Si-Si bonds in the 3-coordinated silicide. Higher frequency vibrations occur due to asymmetric stretching. Electrical conductivity measurements indicate LiSi is a narrow-gap semiconductor ( Eb˜0.057 eV). There is a rapid increase in conductivity above T=450 K, that might be due to the onset of Li + mobility.

Stretchable conductors by kirigami patterning of aramid-silver nanocomposites with zero conductance gradient

NASA Astrophysics Data System (ADS)

Lyu, Jing; Hammig, Mark D.; Liu, Lehao; Xu, Lizhi; Chi, Hang; Uher, Ctirad; Li, Tiehu; Kotov, Nicholas A.

2017-10-01

Materials that are both stretchable and electrically conductive enable a broad spectrum of applications in sensing, actuating, electronics, optics and energy storage. The materials engineering concept of stretchable conductors is primarily based on combining nanowires, nanoribbons, nanoparticles, or nanocarbons with rubbery polymers to obtain composites with different abilities to transport charge and alter their nanoscale organization under strain. Although some of these composites reveal remarkably interesting multiscale reconfigurability and self-assembly phenomena, decreasing conductance with increased strain has restricted their widespread implementation. In a broader physical sense, the dependence of conductance on stress is undesirable because it requires a correlated change of electrical inputs. In this paper, we describe highly conductive and deformable sheets with a conductivity as high as 230 000 S cm-1, composed of silver nanoparticles, infiltrated within a porous aramid nanofiber (ANF) matrix. By forming a kirigami pattern, consisting of a regularized network of notches cut within the films, their ultimate tensile strain is improved from ˜2% to beyond 100%. The use of ANFs derived from well-known ultrastrong Kevlar™ fibers imparts high mechanical performance to the base composite. Importantly, the conductance of the films remains constant, even under large deformation resulting in a material with a zero conductance gradient. Unlike other nanocomposites for which strain and conductance are strongly coupled, the kirigami nanocomposite provides a pathway to demanding applications for flexible and stretchable electronics with power/voltage being unaffected by the deformation mode and temperature.

Date Fruits-Assisted Synthesis and Biocompatibility Assessment of Nickel Oxide Nanoparticles Anchored onto Graphene Sheets for Biomedical Applications.

PubMed

Alshatwi, Ali A; Athinarayanan, Jegan; Periasamy, Vaiyapuri Subbarayan; Alatiah, Khalid A

2017-02-01

Nanographene- and graphene-based nanohybrids have garnered attention in the biomedical community owing to their biocompatibility, excellent aqueous processability, ease of cellular uptake, facile surface functionalization, and thermal and electrical conductivities. NiO nanoparticle-graphene nanohybrid (G-NiO) was synthesized by first depositing Ni(OH) 2 onto the surface of graphene oxide (GO) sheets. The Ni(OH) 2 -GO hybrids were then reduced to G-NiO using date palm syrup at 85 °C. The prepared G-NiO nanohybrids were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The NiO nanoparticles, with a diameter of approximately 20-30 nm, were uniformly dispersed over the surface of the graphene sheets. The G-NiO hybrids exhibit biocompatibility in human mesenchymal stem cells (hMSCs) up to 100 μg/mL. The nanohybrids do not cause any significant changes in cellular and nuclear morphologies in hMSCs. The as-synthesized nanohybrids show excellent biocompatibility and could be a promising material for biomedical applications.

Multilayer ZnO/Pd/ZnO Structure as Sensing Membrane for Extended-Gate Field-Effect Transistor (EGFET) with High pH Sensitivity

NASA Astrophysics Data System (ADS)

Rasheed, Hiba S.; Ahmed, Naser M.; Matjafri, M. Z.; Al-Hardan, Naif H.; Almessiere, Munirah Abdullah; Sabah, Fayroz A.; Al-Hazeem, Nabeel Z.

2017-10-01

Metal oxide nanostructures have attracted considerable attention as pH-sensitive membranes because of their unique advantages. Specifically, the special properties of ZnO thin film, including high surface-to-volume ratio, nontoxicity, thermal stability, chemical stability, electrochemical activity, and high mechanical strength, have attracted massive interest. ZnO exhibits wide bandgap of 3.37 eV, good biocompatibility, high reactivity, robustness, and environmental stability. These unique properties explain why ZnO has the most applications among all nanostructured metal oxides based on its structure and properties. Moreover, ZnO has excellent electrical characteristics, enabling its use in accurate sensors with rapid response. ZnO nanostructures can be used in novel pH and biomedical sensing applications. However, ZnO thin film exhibits large sheet resistance and low conductivity. Increasing the conductivity or reducing the resistivity of ZnO sensing membranes is important to achieve low impedance. We propose herein a new design using a multilayer ZnO/Pd/ZnO structure as a pH-sensing membrane. Multiple layers were deposited by radio frequency (RF) sputtering for ZnO and direct current (DC) sputtering for Pd to achieve low sheet resistance. These multilayers with low sheet resistance of 15.8 Ω/sq were then successfully used to control the conductivity in extended-gate field-effect transistors (EGFETs). The resulting multilayered EGFET pH-sensor demonstrated improved sensing performance. The measured sensitivity of the pH sensor was 40 μA/pH and 52 mV/pH within the pH range from 2 to 12, rendering this structure suitable for use in various applications, including pH sensors and biosensors.

Estimation Model for Magnetic Properties of Stamped Electrical Steel Sheet

NASA Astrophysics Data System (ADS)

Kashiwara, Yoshiyuki; Fujimura, Hiroshi; Okamura, Kazuo; Imanishi, Kenji; Yashiki, Hiroyoshi

Less deterioration in magnetic properties of electrical steel sheets in the process of stamping out iron-core are necessary in order to maintain its performance. First, the influence of plastic strain and stress on magnetic properties was studied by test pieces, in which plastic strain was added uniformly and residual stress was not induced. Because the influence of plastic strain was expressed by equivalent plastic strain, at each equivalent plastic strain state the influence of load stress was investigated. Secondly, elastic limit was determined about 60% of macroscopic yield point (MYP), and it was found to agree with stress limit inducing irreversible deterioration in magnetic properties. Therefore simulation models, where beyond elastic limit plastic deformation begins and magnetic properties are deteriorated steeply, are proposed. Besides considered points in the deformation analysis are strain-rate sensitivity of flow stress, anisotropy under deformation, and influence of stress triaxiality on fracture. Finally, proposed models have been shown to be valid, because magnetic properties of 5mm width rectangular sheets stamped out from non-oriented electrical steel sheet (35A250 JIS grade) can be estimated with good accuracy. It is concluded that the elastic limit must be taken into account in both stamping process simulation and magnetic field calculation.

Solution-processed assembly of ultrathin transparent conductive cellulose nanopaper embedding AgNWs.

PubMed

Song, Yuanyuan; Jiang, Yaoquan; Shi, Liyi; Cao, Shaomei; Feng, Xin; Miao, Miao; Fang, Jianhui

2015-08-28

Natural biomass based cellulose nanopaper is becoming a promising transparent substrate to supersede traditional petroleum based polymer films in realizing future flexible paper-electronics. Here, ultrathin, highly transparent, outstanding conductive hybrid nanopaper with excellent mechanical flexibility was synthesized by the assembly of nanofibrillated cellulose (NFC) and silver nanowires (AgNWs) using a pressured extrusion paper-making technique. The hybrid nanopaper with a thickness of 4.5 μm has a good combination of transparent conductive performance and mechanical stability using bamboo/hemp NFC and AgNWs cross-linked by hydroxypropylmethyl cellulose (HPMC). The heterogeneous fibrous structure of BNFC/HNFC/AgNWs endows a uniform distribution and an enhanced forward light scattering, resulting in high electrical conductivity and optical transmittance. The hybrid nanopaper with an optimal weight ratio of BNFC/HNFC to AgNWs shows outstanding synergistic properties with a transmittance of 86.41% at 550 nm and a sheet resistance of 1.90 ohm sq(-1), equal to the electronic conductivity, which is about 500 S cm(-1). The BNFC/HNFC/AgNW hybrid nanopaper maintains a stable electrical conductivity after the peeling test and bending at 135° for 1000 cycles, indicating remarkably strong adhesion and mechanical flexibility. Of importance here is that the high-performance and low-cost hybrid nanopaper shows promising potential for electronics application in solar cells, flexible displays and other high-technology products.

Electrical properties of graphene film for counter electrode in dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Khalifa, Ali; Shafie, S.; Hasan, W. Z. W.; Lim, H. N.; Rusop, M.; Samaila, Buda

2018-05-01

A graphene counter electrode for dye-sensitized solar cell was prepared simply by drop casting method on a conducting FTO glass at room temperature. Raman spectroscopy was used to study the defection in the graphene films. The sheet resistance was also measured and recoded minimum value of 7.04 Ω/□ at 22.19µm thickness. The casted films show good adhesion to substrates with low defects. A DSSC based on graphene counter electrode demonstrates reasonable conversion efficiency of 2.78% with short circuit current of 7.60mA, open circuit voltage of 0.69V and fill factor of 0.52. The high conductivity and low defects render the prepared graphene dispersion for DSSCs' CE application.

Polymer/graphite oxide composites as high-performance materials for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Tien, Chien-Pin; Teng, Hsisheng

A single graphene sheet represents a carbon material with the highest surface area available to accommodating molecules or ions for physical and chemical interactions. Here we demonstrate in an electric double layer capacitor the outstanding performance of graphite oxide for providing a platform for double layer formation. Graphite oxide is generally the intermediate compound for obtaining separated graphene sheets. Instead of reduction with hydrazine, we incorporate graphite oxide with a poly(ethylene oxide)-based polymer and anchor the graphene oxide sheets with poly(propylene oxide) diamines. This polymer/graphite oxide composite shows in a "dry" gel-electrolyte system a double layer capacitance as high as 130 F g -1. The polymer incorporation developed here can significantly diversify the application of graphene-based materials in energy storage devices.

2. Photocopy of drawing (1976 structural and electrical drawing by ...

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

2. Photocopy of drawing (1976 structural and electrical drawing by the Strategic Air Command, USAF) SITE PLAN, STRUCTURAL AND ELECTRICAL FOR RELOCATING WAREHOUSE, SHEET 1 OF 1 - Vandenberg Air Force Base, Space Launch Complex 3, Storage Shed, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

75 FR 8691 - Combined Notice of Filings # 3

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-25

..., 2010. Take notice that the Commission received the following electric rate filings: Docket Numbers.... Applicants: Xcel Energy Services Inc. Description: Northern States Power Company et al submits Original Sheet 1 et al to FERC Electric Tariff, Original Volume 3--FERC Electric Rate Schedule 280-NSP. Filed Date...

75 FR 141 - Big Rivers Electric Corporation; Notice of Filing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-04

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. NJ09-3-001] Big Rivers Electric Corporation; Notice of Filing December 23, 2009. Take notice that on December 16, 2009, pursuant... Rivers Electric Corporation filed revised tariff sheets to its ``safe harbor'' open access transmission...

Triboelectric-based harvesting of gas flow energy and powerless sensing applications

NASA Astrophysics Data System (ADS)

Taghavi, Majid; Sadeghi, Ali; Mazzolai, Barbara; Beccai, Lucia; Mattoli, Virgilio

2014-12-01

In this work, we propose an approach that can convert gas flow energy to electric energy by using the triboelectric effect, in a structure integrating at least two conductive parts (i.e. electrodes) and one non-conductive sheet. The gas flow induces vibration of the cited parts. Therefore, the frequent attaching and releasing between a non-conductive layer with at least one electrode generates electrostatic charges on the surfaces, and then an electron flow between the two electrodes. The effect of blown gas on the output signals is studied to evaluate the gas flow sensing. We also illustrate that the introduced system has an ability to detect micro particles driven by air into the system. Finally we show how we can use this approach for a self sustainable system demonstrating smoke detection and LED lightening.

Development of a Solar Cell Back Sheet with Excellent UV Durability and Thermal Conductivity.

PubMed

Kang, Seong-Hwan; Choi, Jaeho; Lee, Sung-Ho; Song, Young-Hoon; Park, Jong-Se; Jung, In-Sung; Jung, Jin-Su; Kim, Chong-Yeal; Yang, O-Bong

2018-09-01

The back sheet is one of the most important materials in photovoltaic (PV) modules. It plays an important role in protecting the solar cell from the environment by preventing moisture penetration. In the back sheet, the outermost layer is composed of a polyester (PET) film to protect the PV module from moisture, and the opposite layer is composed of a TiO2 + PE material. Nowadays, PV modules are installed in the desert. Therefore, methods to improve the power generation efficiency of PV modules need to be investigated as the efficiency is affected by temperature resulting from the heat radiation effect. Using a back sheet with a high thermal conductivity, the module output efficiency can be increased as heat is efficiently dissipated. In this study, a thermally conductive film was fabricated by mixing a reference film (TiO2 + PE) and a non-metallic material, MgO, with high thermal conductivity. UV irradiation tests of the film were conducted. The thermally conductive film (TiO2 + PE + MgO) showed higher conductivity than a reference film. No visible cracks and low yellowing degree were found in thermally conductive film, confirming its excellent UV durability characteristics. The sample film was bonded to a PET layer, and a back sheet was fabricated. The yellowing of the back sheet was also analyzed after UV irradiation. In addition, mini modules with four solar cell were fabricated using the developed back sheet, and a comparative outdoor test was conducted. The results showed that power generation improved by 1.38%.

Electrical Experiments. VT-214-12-1. Part I. Electric Motor Control.

ERIC Educational Resources Information Center

Connecticut State Dept. of Education, Hartford. Div. of Vocational Education.

Designed for high school electronics students, this first document in a series of six electrical learning activity packages focuses on electric motor control. An introductory section gives the objective for the activities, an introduction, and an outline of the content. The remainder of the activity book is comprised of information sheets and job…

Magnetic properties of electrical iron sheet under controlled magnetization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takada, Shunji; Sasaki, Tadashi

1993-11-01

Power losses of electrical iron sheet were measured under the controlled magnetizing condition in which magnetic induction changes at a constant time rate for a fixed time and pauses at a certain induction for a varied time in every half magnetizing cycle. Considerable increase of losses per magnetizing cycle with a pause time has been found only in the case of magnetization pause at the maximum induction. The increase of losses is considered from magnetostriction measurements to be caused by internal magnetization rearrangement accompanied with flux reversal after the pause period.

Identification of Skin Electrical Injury Using Infrared Imaging: A Possible Complementary Tool for Histological Examination

PubMed Central

Lin, Hancheng; Wang, Zhenyuan; Dong, Hongmei

2017-01-01

In forensic practice, determination of electrocution as a cause of death usually depends on the conventional histological examination of electrical mark in the body skin, but the limitation of this method includes subjective bias by different forensic pathologists, especially for identifying suspicious electrical mark. The aim of our work is to introduce Fourier transform infrared (FTIR) spectroscopy in combination with chemometrics as a complementary tool for providing an relatively objective diagnosis. The results of principle component analysis (PCA) showed that there were significant differences of protein structural profile between electrical mark and normal skin in terms of α-helix, antiparallel β-sheet and β-sheet content. Then a partial least square (PLS) model was established based on this spectral dataset and used to discriminate electrical mark from normal skin areas in independent tissue sections as revealed by color-coded digital maps, making the visualization of electrical injury more intuitively. Our pilot study demonstrates the potential of FTIR spectroscopy as a complementary tool for diagnosis of electrical mark. PMID:28118398

Magnetosphere-Ionosphere Coupling and Associated Ring Current Energization Processes

NASA Technical Reports Server (NTRS)

Liemohn, M. W.; Khazanov, G. V.

2004-01-01

Adiabatic processes in the ring current are examined. In particular, an analysis of the factors that parameterize the net adiabatic energy gain in the inner magnetosphere during magnetic storms is presented. A single storm was considered, that of April 17, 2002. Three simulations were conducted with similar boundary conditions but with different electric field descriptions. It is concluded that the best parameter for quantifying the net adiabatic energy gain in the inner magnetosphere during storms is the instantaneous value of the product of the maximum westward electric field at the outer simulation boundary with the nightside plasma sheet density. However, all of the instantaneous magnetospheric quantities considered in this study produced large correlation coefficients. Therefore, they all could be considered useful predictors of the net adiabatic energy gain of the ring current. Long integration times over the parameters lessen the significance of the correlation. Finally, some significant differences exist in the correlation coefficients depending on the electric field description.

Influence of sputtering deposition parameters on electrical and optical properties of aluminium-doped zinc oxide thin films for photovoltaic applications

NASA Astrophysics Data System (ADS)

Krawczak, Ewelina; Agata, Zdyb; Gulkowski, Slawomir; Fave, Alain; Fourmond, Erwann

2017-11-01

Transparent Conductive Oxides (TCOs) characterized by high visible transmittance and low electrical resistivity play an important role in photovoltaic technology. Aluminum doped zinc oxide (AZO) is one of the TCOs that can find its application in thin film solar cells (CIGS or CdTe PV technology) as well as in other microelectronic applications. In this paper some optical and electrical properties of ZnO:Al thin films deposited by RF magnetron sputtering method have been investigated. AZO layers have been deposited on the soda lime glass substrates with use of variable technological parameters such as pressure in the deposition chamber, power applied and temperature during the process. The composition of AZO films has been investigated by EDS method. Thickness and refraction index of the deposited layers in dependence on certain technological parameters of sputtering process have been determined by spectroscopic ellipsometry. The measurements of transmittance and sheet resistance were also performed.

Perforating Thin Metal Sheets

NASA Technical Reports Server (NTRS)

Davidson, M. E.

1985-01-01

Sheets only few mils thick bonded together, punched, then debonded. Three-step process yields perforated sheets of metal. (1): Individual sheets bonded together to form laminate. (2): laminate perforated in desired geometric pattern. (3): After baking, laminate separates into individual sheets. Developed for fabricating conductive layer on blankets that collect and remove ions; however, perforated foils have other applications - as conductive surfaces on insulating materials; stiffeners and conductors in plastic laminates; reflectors in antenna dishes; supports for thermal blankets; lightweight grille cover materials; and material for mockup of components.

Magnetic characterization of the stator core of a high-speed motor made of an ultrathin electrical steel sheet using the magnetic property evaluation system

NASA Astrophysics Data System (ADS)

Oka, Mohachiro; Enokizono, Masato; Mori, Yuji; Yamazaki, Kazumasa

2018-04-01

Recently, the application areas for electric motors have been expanding. For instance, electric motors are used in new technologies such as rovers, drones, cars, and robots. The motor used in such machinery should be small, high-powered, highly-efficient, and high-speed. In such motors, loss at high-speed rotation must be especially minimal. Eddy-current loss in the stator core is known to increase greatly during loss at high-speed rotation of the motor. To produce an efficient high-speed motor, we are developing a stator core for a motor using an ultrathin electrical steel sheet with only a small amount of eddy-current loss. Furthermore, the magnetic property evaluation for efficient, high-speed motor stator cores that use conventional commercial frequency is insufficient. Thus, we made a new high-speed magnetic property evaluation system to evaluate the magnetic properties of the efficient high-speed motor stator core. This system was composed of high-speed A/D converters, D/A converters, and a high-speed power amplifier. In experiments, the ultrathin electrical steel sheet dramatically suppressed iron loss and, in particular, eddy-current loss. In addition, a new high-speed magnetic property evaluation system accurately evaluated the magnetic properties of the efficient high-speed motor stator core.

49 CFR 1245.6 - Cross reference to standard occupational classification manual.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... Assist. Chemist 1845. X-ray Technician 365. Supv. Estimating 149. Junior Engineer 1639. Engineer Trainee...) 8319. Grain Elevator Operator (electrical) 8319. 414Machinists: Machinist 6813. 415Sheet Metal Workers: Sheet Metal Worker 6824. 416Skilled Trades, Helpers, Maintenance of Equipment and Stores: Helper 861...

Technical feasibility and economical viability of remote hybrid power systems in Northern Ontario

NASA Astrophysics Data System (ADS)

Gubbels, Jason Matthew

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Evaluation of remotely sensed wetland mapping

NASA Astrophysics Data System (ADS)

Gluck, Michael J.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Effects of propagational factors on quantum wires in close parallel proximity

NASA Astrophysics Data System (ADS)

Wilson, David A.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Tectonic magnetic fabrics in pure and simple shear: Experimental investigations

NASA Astrophysics Data System (ADS)

Alford, Craig Steven

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Use of a single epiphyte lichen species Hypogymnia physodes as an indicator of air quality in northern Ontario

NASA Astrophysics Data System (ADS)

Pfeiffer, Helmut Nickolaus

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Gravity study of an Archaen crustal segment near Thunder Bay, Ontario

NASA Astrophysics Data System (ADS)

Cheadle, Scott Philip

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Northern lights: A history of Thunder Bay Hydro

NASA Astrophysics Data System (ADS)

Black, David Leo

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Static dielectric properties of an ensemble of restricted one-dimensional oscillators

NASA Astrophysics Data System (ADS)

Tjipto Margo, Broto

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Photoluminescence and Raman characterization of PLEE and MBE grown semiconductor epilayers

NASA Astrophysics Data System (ADS)

Harrison, Dale A.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Development of nonlinear 3-D, and novel 2-D optical microscope imaging systems for time-lapse imaging

NASA Astrophysics Data System (ADS)

Girardin, Robert Joseph

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Simple route to new palladium-carbonyl-bis(diphenylphosphino)methane complexes

NASA Astrophysics Data System (ADS)

Krysa, Elizabeth

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Photon number density operator

NASA Astrophysics Data System (ADS)

Melde, Thomas

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Dielectric and infrared studies of radio frequency processes in some alcohols

NASA Astrophysics Data System (ADS)

Mandal, Humayun

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Real-time implementation of some attitude estimation algorithms on a quadrotor UAV

NASA Astrophysics Data System (ADS)

Nayak, Siddhant

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Aligned Carbon Nanotubes for High-Performance Films and Composites

NASA Astrophysics Data System (ADS)

Zhang, Liwen

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Ordered supramolecular oligothiophene structures on passivated silicon surfaces

NASA Astrophysics Data System (ADS)

Liu, Renjie

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Synthesis and electrochemical study of PtIr and PtRu nanomaterials

NASA Astrophysics Data System (ADS)

Alammari, Walaa S.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

P-type gallium nitride semiconductor development and characterization for LEDs and other devices

NASA Astrophysics Data System (ADS)

Togtema, Gregorey L.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

4. PHOTOCOPY OF DRAWING (1976 STRUCTURAL AND ELECTRICAL DRAWING BY ...

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

4. PHOTOCOPY OF DRAWING (1976 STRUCTURAL AND ELECTRICAL DRAWING BY THE SPACE AND MISSILE TEST CENTER, VAFB, USAF) STRUCTURAL AND ELECTRICAL DIAGRAM FOR EQUIPMENT STORAGE BUILDING, SHEET S-26 - Vandenberg Air Force Base, Space Launch Complex 3, Storage Shed, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

Modelling GIC Flow in New Zealand's Electrical Transmission Grid

NASA Astrophysics Data System (ADS)

Divett, T.; Thomson, A. W. P.; Ingham, M.; Rodger, C. J.; Beggan, C.; Kelly, G.

2016-12-01

Transformers in Transpower New Zealand Ltd's electrical grid have been impacted by geomagnetically induced currents (GIC) during geomagnetic storms, for example in November 2001. In this study we have developed an initial model of the South Island's power grid to advance understanding of the impact of GIC on New Zealand's (NZ) grid. NZ's latitude and island setting mean that modelling approaches successfully used in the UK in the past can be used. Vasseur and Weidelt's thin sheet model is applied to model the electric field as a function of magnetic field and conductance. However the 4 km deep ocean near NZ's coast compared to the UK's relatively shallow continental shelf waters restricts the range of frequency and spatial grid that can be used due to assumptions in the thin sheet model. Some early consequences of these restrictions will be discussed. Lines carrying 220kV, 110kV and 66kV make up NZ's electrical transmission grid with multiple earthing nodes at each substation. Transpower have measured DC earth currents at 17 nodes in NZ's South Island grid for 15 years, including observations at multiple transformers for some substations. Different transformers at the same substation can experience quite different GIC during space weather events. Therefore we have initially modelled each transformer in some substations separately to compare directly with measured currents.Ultimately this study aims to develop a validated modelling tool that will be used to strengthen NZ's grid against the risks of space weather. Further, mitigation tactics which could be used to reduce the threat to the electrical grid will be evaluated. In particular we will focus at the transformer level where the risk lies, and not at the substation level as has been commonly done to date. As we will validate our model against the extensive Transpower observations, this will be a valuable confirmation of the approaches used by the wider international community.

The Effect of Varying Ultrafast Pulse Laser Energies on the Electrical Properties of Reduced Graphene Oxide Sheets in Solution

NASA Astrophysics Data System (ADS)

Ibrahim, Khaled H.; Irannejad, Mehrdad; Wales, Benjamin; Sanderson, Joseph; Musselman, Kevin P.; Yavuz, Mustafa

2018-02-01

Laser treatment of graphene oxide solution among other techniques is a well-established technique for producing reduced graphene sheets. However, production of high-quality ultra-low sheet resistance reduced graphene oxide (rGO) sheets in solution has been a challenge due to their high degree of randomness, defect-rich medium, and lack of controlability. Recent studies lack an in-depth analytic comparison of laser treatment parameters that yield the highest quality rGO sheets with a low defect ratio. Hence, in this study, we implement a comprehensive comparison of laser treatment parameters and their effect on the yielded rGO sheets from an electronic and physical standpoint. Ultra-low sheet resistance graphene oxide sheets were fabricated using ultrafast laser irradiation with different laser pulse energies in the range of 0.25-2 mJ. Laser treatment for 10 min using a pulse energy of 1 mJ resulted in an increase in the defect spacing, accompanied by a large red shift in the optical absorption of the C=C bond, indicating significant restoration of the s p 2 carbon bonds. These enhancements resulted in a significant reduction in the electrical resistance of the rGO flakes (up to 2 orders of magnitude), raising the electron mobility of the films produced using the irradiated graphene oxide a step closer to that of pristine graphene films. From this study, we can also deduce which exposure regimes result in the fabrication of quantum dots and continuous defect-free films.

Thin and long silver nanowires self-assembled in ionic liquids as a soft template: electrical and optical properties

NASA Astrophysics Data System (ADS)

Chang, Min-Hwa; Cho, Hyun-Ah; Kim, Youn-Soo; Lee, Eun-Jong; Kim, Jin-Yeol

2014-07-01

Thin and long silver nanowires were successfully synthesized using the polyvinylpyrrolidone (PVP)-assisted polyol method in the presence of ionic liquids, tetrapropylammonium chloride and tetrapropylammonium bromide, which served as soft template salts. The first step involved the formation of Ag nanoparticles with a diameter of 40 to 50 nm through the reduction of silver nitrate. At the growing stage, the Ag nanoparticles were converted into thin and long one-dimensional wires, with uniform diameters of 30 ± 3 nm and lengths of up to 50 μm. These Ag nanowires showed an electrical conductivity of 0.3 × 105 S/cm, while the sheet resistance of a two-dimensional percolating Ag nanowire network exhibited a value of 20 Ω/sq with an optical transmittance of 93% and a low haze value.

Dielectric and relaxation properties of poly(o-anisidine)/graphene nanocomposite

NASA Astrophysics Data System (ADS)

Sangamithirai, D.; Narayanan, V.; Stephen, A.

2016-05-01

Poly(o-anisidine)/graphene (POA/GR) nanocomposite was synthesized via chemical oxidative polymerization of o-anisidine in the presence of graphene sheets in acidic medium. The electrical properties of the nanocomposite are studied using AC impedance spectroscopic technique. It has been found that the room temperature electrical conductivity value enhanced from 1.28 × 10-6 S cm-1 to 4.47 × 10-4 S cm-1 on addition of 10 wt % of graphene into the polymer. An analysis of real and imaginary parts of dielectric permittivity reveals that both ɛ` and ɛ״ increases with the decrease of frequency at all temperature levels. Frequency dependence of dielectric loss (tan δ) spectrum indicates that hopping frequency increases with temperature and the relaxation time decreases from 2.67 × 10-5 to 7.28 × 10-6 sec.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This fact sheet describes the collaboration between NREL, SolarCity, and the Hawaiian Electric Companies at the Energy Systems Integration Facility (ESIF) to address the safety, reliability, and stability challenges of interconnecting high penetrations of distributed photovoltaics with the electric power system.

Carbon Nanotubes: Present and Future Commercial Applications

NASA Astrophysics Data System (ADS)

De Volder, Michael F. L.; Tawfick, Sameh H.; Baughman, Ray H.; Hart, A. John

2013-02-01

Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

Carbon nanotubes: present and future commercial applications.

PubMed

De Volder, Michael F L; Tawfick, Sameh H; Baughman, Ray H; Hart, A John

2013-02-01

Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

MgF2 monolayer as an anti-reflecting material

NASA Astrophysics Data System (ADS)

Mahida, H. R.; Singh, Deobrat; Sonvane, Yogesh; Gupta, Sanjeev K.; Thakor, P. B.

2017-02-01

The single-layer atomic sheet of magnesium fluoride (MgF2) having 1H and 1T phase structure (hexagonal and tetragonal phase) has been calculated by density functional theory (DFT). Further, we have investigated the structural, electronic and optical properties such as frequency dependent dielectric function, absorption spectra, energy loss spectra, reflectivity, refractive index and optical conductivity of monolayer MgF2 for the direction of parallel and perpendicular electric field polarizations. Our results suggest that monolayer MgF2 provides promising applications in anti-reflection coatings, high-reflective systems and in opto-electronic materials.

Two-fluid description of wave-particle interactions in strong Buneman turbulence

NASA Astrophysics Data System (ADS)

Che, H.

2014-06-01

To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation while a plasma is unstable to the Buneman instability in force-free current sheets. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions in Buneman instability can be approximately described by a set of electron fluid equations. We show that both energy dissipation and momentum transport along electric current in the current layer are locally quasi-static, but globally dynamic and irreversible. Turbulent drag dissipates both the streaming energy of the current sheet and the associated magnetic energy. The net loss of streaming energy is converted into the electron component heat conduction parallel to the magnetic field and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation that relates the turbulence-induced convective momentum transport and thermal momentum transport. Electron trapping and de-trapping drive local momentum transports, while phase mixing converts convective momentum into thermal momentum. The drag acts like a micro-macro link in the anomalous heating processes. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons, but most of the magnetic energy is dissipated and converted into the component heat of electrons perpendicular to the magnetic field. This heating process is decoupled from the heating of Buneman instability in the current sheets. Ion heating is weak but ions play an important role in assisting energy exchanges between waves and electrons. Cold ion fluid equations together with our electron fluid equations form a complete set of equations that describes the occurrence, growth, saturation and decay of the Buneman instability.

Fabrication of High Content Carbon Nanotube-Polyurethane Sheets with Tailorable Properties.

PubMed

Martinez-Rubi, Yadienka; Ashrafi, Behnam; Jakubinek, Michael B; Zou, Shan; Laqua, Kurtis; Barnes, Michael; Simard, Benoit

2017-09-13

We have fabricated carbon nanotube (CNT)-polyurethane (TPU) sheets via a one-step filtration method that uses a TPU solvent/nonsolvent combination. This solution method allows for control of the composition and processing conditions, significantly reducing both the filtration time and the need for large volumes of solvent to debundle the CNTs. Through an appropriate selection of the solvents and tuning the solvent/nonsolvent ratio, it is possible to enhance the interaction between the CNTs and the polymer chains in solution and improve the CNT exfoliation in the nanocomposites. The composition of the nanocomposites, which defines the characteristics of the material and its mechanical properties, can be precisely controlled. The highest improvements in tensile properties were achieved at a CNT:TPU weight ratio around 35:65 with a Young's modulus of 1270 MPa, stress at 50% strain of 35 MPa, and strength of 41 MPa, corresponding to ∼10-fold improvement in modulus and ∼7-fold improvement in stress at 50% strain, while maintaining a high failure strain. At the same composition, CNTs with higher aspect ratio produce nanocomposites with greater improvements (e.g., strength of 99 MPa). Electrical conductivity also shows a maximum near the same composition, where it can exceed the values achieved for the pristine nanotube buckypaper. The trend in mechanical and electrical properties was understood in terms of the CNT-TPU interfacial interactions and morphological changes occurring in the nanocomposite sheets as a function of increasing the TPU content. The availability of such a simple method and the understanding of the structure-property relationships are expected to be broadly applicable in the nanocomposites field.

Equivalent orthotropic elastic moduli identification method for laminated electrical steel sheets

NASA Astrophysics Data System (ADS)

Saito, Akira; Nishikawa, Yasunari; Yamasaki, Shintaro; Fujita, Kikuo; Kawamoto, Atsushi; Kuroishi, Masakatsu; Nakai, Hideo

2016-05-01

In this paper, a combined numerical-experimental methodology for the identification of elastic moduli of orthotropic media is presented. Special attention is given to the laminated electrical steel sheets, which are modeled as orthotropic media with nine independent engineering elastic moduli. The elastic moduli are determined specifically for use with finite element vibration analyses. We propose a three-step methodology based on a conventional nonlinear least squares fit between measured and computed natural frequencies. The methodology consists of: (1) successive augmentations of the objective function by increasing the number of modes, (2) initial condition updates, and (3) appropriate selection of the natural frequencies based on their sensitivities on the elastic moduli. Using the results of numerical experiments, it is shown that the proposed method achieves more accurate converged solution than a conventional approach. Finally, the proposed method is applied to measured natural frequencies and mode shapes of the laminated electrical steel sheets. It is shown that the method can successfully identify the orthotropic elastic moduli that can reproduce the measured natural frequencies and frequency response functions by using finite element analyses with a reasonable accuracy.

Growth of a Large-Area, Free-Standing, Highly Conductive and Fully Foldable Silver Film with Inverted Pyramids for Wearable Electronics Applications.

PubMed

Yu, Xiao; Li, Zihua; Liu, Yong; Zhao, Wenxia; Xu, Ruimei; Wang, Donghai; Shen, Hui

2017-02-15

A promising new concept is the application of flexible and foldable conductive film or paper for wearable electronics, in which silver nanowires, carbon nanotubes, and graphene are primarily used as conductive materials. However, their insufficient nanostructure contacts lead to poor electrical conductivity and mechanical fracture. Here, we demonstrate a simple and innovative strategy for fabricating a free-standing silver film with inverted pyramids by replicating pyramids on a textured silicon wafer under a hydrothermal reaction. In this unique structure, the inverted pyramids on the film surface can provide sufficient buffer space for a mechanically foldable and unfoldable cushion, and the continuous film ensures an uninterrupted electron transport pathway. As a result, the silver film with inverted pyramids can exhibit extremely high conductivity, with a sheet resistance as low as 2.55 × 10 -3 Ω/sq, corresponding to an electrical conductivity of 4.2 × 10 5 S cm -1 for a 9.2-μm-thick film (67.7% of bulk silver's conductivity). Surprisingly, this film has outstanding mechanical folding stability, with less than a 0.5% deviation from the initial resistance after 35,000 repetitive folding and unfolding cycles when tested at the folding site. The film is free-standing, thin, flexible, foldable, and suitable for cutting and patterned growth, which makes it suitable for wearable electronics, showing a much wider range of applications than substrate-based ones.

Transparent and Flexible Large-scale Graphene-based Heater

NASA Astrophysics Data System (ADS)

Kang, Junmo; Lee, Changgu; Kim, Young-Jin; Choi, Jae-Boong; Hong, Byung Hee

2011-03-01

We report the application of transparent and flexible heater with high optical transmittance and low sheet resistance using graphene films, showing outstanding thermal and electrical properties. The large-scale graphene films were grown on Cu foil by chemical vapor deposition methods, and transferred to transparent substrates by multiple stacking. The wet chemical doping process enhanced the electrical properties, showing a sheet resistance as low as 35 ohm/sq with 88.5 % transmittance. The temperature response usually depends on the dimension and the sheet resistance of the graphene-based heater. We show that a 4x4 cm2 heater can reach 80& circ; C within 40 seconds and large-scale (9x9 cm2) heater shows uniformly heating performance, which was measured using thermocouple and infra-red camera. These heaters would be very useful for defogging systems and smart windows.

Second-order nonlinear optical microscopy of spider silk

NASA Astrophysics Data System (ADS)

Zhao, Yue; Hien, Khuat Thi Thu; Mizutani, Goro; Rutt, Harvey N.

2017-06-01

Asymmetric β-sheet protein structures in spider silk should induce nonlinear optical interaction such as second harmonic generation (SHG) which is experimentally observed for a radial line and dragline spider silk using an imaging femtosecond laser SHG microscope. By comparing different spider silks, we found that the SHG signal correlates with the existence of the protein β-sheets. Measurements of the polarization dependence of SHG from the dragline indicated that the β-sheet has a nonlinear response depending on the direction of the incident electric field. We propose a model of what orientation the β-sheet takes in spider silk.

Equivalence Between Squirrel Cage and Sheet Rotor Induction Motor

NASA Astrophysics Data System (ADS)

Dwivedi, Ankita; Singh, S. K.; Srivastava, R. K.

2016-06-01

Due to topological changes in dual stator induction motor and high cost of its fabrication, it is convenient to replace the squirrel cage rotor with a composite sheet rotor. For an experimental machine, the inner and outer stator stampings are normally available whereas the procurement of rotor stampings is quite cumbersome and is not always cost effective. In this paper, the equivalence between sheet/solid rotor induction motor and squirrel cage induction motor has been investigated using layer theory of electrical machines, so as to enable one to utilize sheet/solid rotor in dual port experimental machines.

Plasmon-polaritonic bands in sequential doped graphene superlattices

NASA Astrophysics Data System (ADS)

Ramos-Mendieta, Felipe; Palomino-Ovando, Martha; Hernández-López, Alejandro; Fuentecilla-Cárcamo, Iván

Doped graphene has the extraordinary quality of supporting two types of surface excitations that involve electric charges (the transverse magnetic surface plasmons) or electric currents (the transverse electric modes). We have studied numerically the collective modes that result from the coupling of surface plasmons in doped graphene multilayers. By use of structured supercells with fixed dielectric background and inter layer separation, we found a series of plasmon-polaritonic bands of structure dependent on the doping sequence chosen for the graphene sheets. Periodic and quasiperiodic sequences for the graphene chemical potential have been studied. Our results show that transverse magnetic bands exist only in the low frequency regime but transverse electric bands arise within specific ranges of higher frequencies. Our calculations are valid for THz frequencies and graphene sheets with doping levels between 0.1 eV and 1.2 eV have been considered. AHL and IFC aknowledge fellowship support from CONACYT México.

Localized conductive patterning via focused electron beam reduction of graphene oxide

NASA Astrophysics Data System (ADS)

Kim, Songkil; Kulkarni, Dhaval D.; Henry, Mathias; Zackowski, Paul; Jang, Seung Soon; Tsukruk, Vladimir V.; Fedorov, Andrei G.

2015-03-01

We report on a method for "direct-write" conductive patterning via reduction of graphene oxide (GO) sheets using focused electron beam induced deposition (FEBID) of carbon. FEBID treatment of the intrinsically dielectric graphene oxide between two metal terminals opens up the conduction channel, thus enabling a unique capability for nanoscale conductive domain patterning in GO. An increase in FEBID electron dose results in a significant increase of the domain electrical conductivity with improving linearity of drain-source current vs. voltage dependence, indicative of a change of graphene oxide electronic properties from insulating to semiconducting. Density functional theory calculations suggest a possible mechanism underlying this experimentally observed phenomenon, as localized reduction of graphene oxide layers via interactions with highly reactive intermediates of electron-beam-assisted dissociation of surface-adsorbed hydrocarbon molecules. These findings establish an unusual route for using FEBID as nanoscale lithography and patterning technique for engineering carbon-based nanomaterials and devices with locally tailored electronic properties.

The use of hydrogel as an electrode-skin interface for electrode array FES applications.

PubMed

Cooper, Glen; Barker, Anthony T; Heller, Ben W; Good, Tim; Kenney, Laurence P J; Howard, David

2011-10-01

Functional electrical stimulation is commonly used to restore function in post-stroke patients in upper and lower limb applications. Location of the electrodes can be a problem hence some research groups have begun to experiment with electrode arrays. Electrode arrays are interfaced with a thin continuous hydrogel sheet which is high resistivity to reduce transverse currents between electrodes in the array. Research using electrode arrays has all been conducted in a laboratory environment over short time periods but it is suspected that this approach will not be feasible over longer time periods due to changes in hydrogel resistivity. High resistivity hydrogel samples were tested by leaving them in contact with the skin over a seven day period. The samples became extremely conductive with resistivities reaching around 10-50 Ωm. The effect of these resistivity changes was studied using finite element analysis to solve for the stationary current quasi-static electric field gradient in the tissue. Electrical stimulation efficiency and focality were calculated for both a high and low resistivity electrode-skin interface layer at different tissue depths. The results showed that low resistivity hydrogel produced significant decreases in stimulation efficiency and focality compared to high resistivity hydrogel. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Auroral Substorms: Search for Processes Causing the Expansion Phase in Terms of the Electric Current Approach

NASA Astrophysics Data System (ADS)

Akasofu, Syun-Ichi

2017-10-01

Auroral substorms are mostly manifestations of dissipative processes of electromagnetic energy. Thus, we consider a sequence of processes consisting of the power supply (dynamo), transmission (currents/circuits) and dissipations (auroral substorms-the end product), namely the electric current line approach. This work confirms quantitatively that after accumulating magnetic energy during the growth phase, the magnetosphere unloads the stored magnetic energy impulsively in order to stabilize itself. This work is based on our result that substorms are caused by two current systems, the directly driven (DD) current system and the unloading system (UL). The most crucial finding in this work is the identification of the UL (unloading) current system which is responsible for the expansion phase. A very tentative sequence of the processes leading to the expansion phase (the generation of the UL current system) is suggested for future discussions. (1) The solar wind-magnetosphere dynamo enhances significantly the plasma sheet current when its power is increased above 10^{18} erg/s (10^{11} w). (2) The magnetosphere accumulates magnetic energy during the growth phase, because the ionosphere cannot dissipate the increasing power because of a low conductivity. As a result, the magnetosphere is inflated, accumulating magnetic energy. (3) When the power reaches 3-5× 10^{18} erg/s (3-5× 10^{11} w) for about one hour and the stored magnetic energy reaches 3-5×10^{22} ergs (10^{15} J), the magnetosphere begins to develop perturbations caused by current instabilities (the current density {≈}3× 10^{-12} A/cm2 and the total current {≈}106 A at 6 Re). As a result, the plasma sheet current is reduced. (4) The magnetosphere is thus deflated. The current reduction causes partial B/partial t > 0 in the main body of the magnetosphere, producing an earthward electric field. As it is transmitted to the ionosphere, it becomes equatorward-directed electric field which drives both Pedersen and Hall currents and thus generates the UL current system. (5) A significant part of the magnetic energy is accumulated in the main body of the magnetosphere (the inner plasma sheet) between 4 Re and 10 Re, because the power (Poynting flux [ E × B ]) is mainly directed toward this region which can hold the substorm energy. (6) The substorm intensity depends on the location of the energy accumulation (between 4 Re and 10 Re), the closer the location to the earth, the more intense substorms becomes, because the capacity of holding the energy is higher at closer distances. The convective flow toward the earth brings both the ring current and the plasma sheet current closer when the dynamo power becomes higher. This proposed sequence is not necessarily new. Individual processes involved have been considered by many, but the electric current approach can bring them together systematically and provide some new quantitative insights.

Exploiting both optical and electrical anisotropy in nanowire electrodes for higher transparency.

PubMed

Dong, Jianjin; Goldthorpe, Irene A

2018-01-26

Transparent electrodes such as indium tin oxide and random meshes of silver nanowires (AgNWs) have isotropic in-plane properties. However, we show that imparting some alignment to AgNWs can create anisotropic transparency and electrical conductivity characteristics that may benefit many applications. For example, liquid crystal displays and the touch sensors on top of them often only need to be transparent to one type of polarized light as well as predominantly conductive in only one direction. Herein, AgNWs are slightly preferentially aligned during their deposition by rod coating. Compared to randomly oriented AgNW films, the alignment boosts the transparency to perpendicularly polarized light, as well as achieves a higher transparency for a given sheet resistance in one direction compared to randomly oriented AgNWs films. These factors together increase the transparency of a 16 Ω/sq electrode by 7.3 percentage points. The alignment technique is cheap and scalable, compatible with roll-to-roll processes, and most importantly does not require extra processing steps, as rod coating is already a standard process for AgNW electrode fabrication.

Anomalous electrical conductivity of a gold thin film percolation system

NASA Astrophysics Data System (ADS)

Tao, Xiang-Ming; Ye, Gao-Xiang; Ye, Quan-Lin; Jin, Jin-Sheng; Lao, Yan-Feng; Jiao, Zheng-Kuan

2002-09-01

A gold thin film percolation system, deposited on a glass surface by the vapor deposition method, has been fabricated. By using the expansive and mobile properties of the silicone oil drop, a characteristic wedge-shaped film system with a slope of ~10-5 naturally forms during deposition. The electrical conductivity of the bandlike film, i.e., the uniform part of the wedge-shaped film with a fixed thickness, is measured with the four-probe method. It is found that the hopping and tunneling effects of the films are stronger than those of the other films. The dependence between the dc sheet resistance R0 and temperature T shows that the samples exhibit a negative coefficient dR0/dT below the temperature T*. According to our experiment, it is suggested that all the anomalous behaviors of the system should be related to the characteristic microstructure of the samples, which results from the immediate quench processes by the oil drop during deposition. The experiment indicates that the relaxation period of the microstructure of the samples may be longer than 30 min.

Electrical, optical and structural properties of transparent conducting Al doped ZnO (AZO) deposited by sol-gel spin coating

NASA Astrophysics Data System (ADS)

Tonny, Kaniz Naila; Rafique, Rosaleena; Sharmin, Afrina; Bashar, Muhammad Shahriar; Mahmood, Zahid Hasan

2018-06-01

Al doped ZnO (AZO) films are fabricated by using sol-gel spin coating method and changes in electrical, optical and structural properties due to variation in film thickness is studied. AZO films provide c-axis orientation along the (002) plane and peak sharpness increased with film thickness is evident from XRD analysis. Conductivity (σ) of AZO films has increased from 2.34 (Siemens/cm) to 20156.27 (Siemens/cm) whereas sheet resistance (Rsh) decreases from 606300 (ohms/sq.) to 2.08 (ohm/sq.) with increase of film thickness from 296 nm to 1030 nm. Optical transmittance (T%) of AZO films is decreased from around 82% to 62% in the visible region. And grain size (D) of AZO thin films has been found to increase from 19.59 nm to 25.25 nm with increase of film thickness. Figure of Merit is also calculated for prepared sample of AZO. Among these four sample of AZO thin films, L-15 sample (having thickness in 895 nm) has provided highest figure of merit which is 5.49*10^-4 (Ω-1).

A facile fabrication of chemically converted graphene oxide thin films and their uses as absorber materials for solar cells

NASA Astrophysics Data System (ADS)

Adelifard, Mehdi; Darudi, Hosein

2016-07-01

There is a great interest in the use of graphene sheets in thin film solar cells with low-cost and good-optoelectronic properties. Here, the production of absorbent conductive reduced graphene oxide (RGO) thin films was investigated. RGO thin films were prepared from spray-coated graphene oxide (GO) layers at various substrate temperature followed by a simple hydrazine-reducing method. The structural, morphological, optical, and electrical characterizations of graphene oxide (GO) and RGO thin films were investigated. X-ray diffraction analysis showed a phase shift from GO to RGO due to hydrazine treatment, in agreement with the FTIR spectra of the layers. FESEM images clearly exhibited continuous films resulting from the overlap of graphene nanosheets. The produced low-cost thin films had high absorption coefficient up to 1.0 × 105 cm-1, electrical resistance as low as 0.9 kΩ/sq, and effective optical band gap of about 1.50 eV, close to the optimum value for solar conversion. The conductive absorbent properties of the reduced graphene oxide thin films would be useful to develop photovoltaic cells.

Exploiting both optical and electrical anisotropy in nanowire electrodes for higher transparency

NASA Astrophysics Data System (ADS)

Dong, Jianjin; Goldthorpe, Irene A.

2018-01-01

Transparent electrodes such as indium tin oxide and random meshes of silver nanowires (AgNWs) have isotropic in-plane properties. However, we show that imparting some alignment to AgNWs can create anisotropic transparency and electrical conductivity characteristics that may benefit many applications. For example, liquid crystal displays and the touch sensors on top of them often only need to be transparent to one type of polarized light as well as predominantly conductive in only one direction. Herein, AgNWs are slightly preferentially aligned during their deposition by rod coating. Compared to randomly oriented AgNW films, the alignment boosts the transparency to perpendicularly polarized light, as well as achieves a higher transparency for a given sheet resistance in one direction compared to randomly oriented AgNWs films. These factors together increase the transparency of a 16 Ω/sq electrode by 7.3 percentage points. The alignment technique is cheap and scalable, compatible with roll-to-roll processes, and most importantly does not require extra processing steps, as rod coating is already a standard process for AgNW electrode fabrication.

214. Photocopy of drawing (1983 electrical drawing by StearnsRoger Incorporated) ...

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

214. Photocopy of drawing (1983 electrical drawing by Stearns-Roger Incorporated) ATLAS H CONVERSION, ELECTRICAL LAN FOR RELOCATION OF THE ERECTION WINCH TO MST STATION 124, SHEET 517-E21 - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

Unitary plate electrode

NASA Technical Reports Server (NTRS)

Rowlette, John J. (Inventor); Clough, Thomas J. (Inventor); Josefowicz, Jack Y. (Inventor); Sibert, John W. (Inventor)

1985-01-01

The unitary electrode (10) comprises a porous sheet (12) of fiberglass the strands (14) of which contain a coating (16) of conductive tin oxide. The lower portion of the sheet contains a layer (18) of resin and the upper layer (20) contains lead dioxide forming a positive active electrode on an electrolyte-impervious layer. The strands (14) form a continuous conduction path through both layers (16, 18). Tin oxide is prevented from reduction by coating the surface of the plate facing the negative electrode with a conductive, impervious layer resistant to reduction such as a thin film (130) of lead or graphite filled resin adhered to the plate with a layer (31) of conductive adhesive. The plate (10) can be formed by casting a molten resin from kettle (60) onto a sheet of glass wool (56) overlying a sheet of lead foil and then applying positive active paste from hopper (64) into the upper layer (68). The plate can also be formed by passing an assembly of a sheet ( 80) of resin, a sheet (86) of sintered glass and a sheet (90) of lead between the nip (92) of heated rollers (93, 95) and then filling lead oxide into the pores (116) of the upper layer (118).

On magnetohydrodynamic flow of second grade nanofluid over a nonlinear stretching sheet

NASA Astrophysics Data System (ADS)

Hayat, Tasawar; Aziz, Arsalan; Muhammad, Taseer; Ahmad, Bashir

2016-06-01

This research article addresses the magnetohydrodynamic (MHD) flow of second grade nanofluid over a nonlinear stretching sheet. Heat and mass transfer aspects are investigated through the thermophoresis and Brownian motion effects. Second grade fluid is assumed electrically conducting through a non-uniform applied magnetic field. Mathematical formulation is developed subject to small magnetic Reynolds number and boundary layer assumptions. Newly constructed condition having zero mass flux of nanoparticles at the boundary is incorporated. Transformations have been invoked for the reduction of partial differential systems into the set of nonlinear ordinary differential systems. The governing nonlinear systems have been solved for local behavior. Graphical results of different influential parameters are studied and discussed in detail. Computations for skin friction coefficient and local Nusselt number have been carried out. It is observed that the effects of thermophoresis parameter on the temperature and nanoparticles concentration distributions are qualitatively similar. The temperature and nanoparticles concentration distributions are enhanced for the larger magnetic parameter.

Mechanical and optoelectric properties of post-annealed fluorine-doped tin oxide films by ultraviolet laser irradiation

NASA Astrophysics Data System (ADS)

Tseng, Shih-Feng; Hsiao, Wen-Tse; Chiang, Donyau; Huang, Kuo-Cheng; Chou, Chang-Pin

2011-06-01

The fluorine-doped tin oxide (FTO) thin film deposited on a soda-lime glass substrate was annealed by a defocus ultraviolet (UV) laser irradiation at ambient temperature. The mechanical and optoelectric properties of FTO films annealed by using the various laser processing parameters were reported. After the FTO films were subjected to laser post-annealing, the microhardness were slightly less but the reduced modulus values were larger than that of unannealed FTO films, respectively. The average optical transmittance in the visible waveband slightly increased with increasing the laser annealing energy and scan speed. Moreover, all the sheet resistance of laser annealed films was less than that of the unannealed ones. We found that the sheet resistance decrease was obviously influenced by annealing. The suitable annealing conditions could maintain the film thickness and relief the internal stress generated in the film preparation process to improve the electrical conductivity via decreasing laser energy or increasing scan speed.

Graphene as a transparent conducting and surface field layer in planar Si solar cells.

PubMed

Kumar, Rakesh; Mehta, Bodh R; Bhatnagar, Mehar; S, Ravi; Mahapatra, Silika; Salkalachen, Saji; Jhawar, Pratha

2014-01-01

This work presents an experimental and finite difference time domain (FDTD) simulation-based study on the application of graphene as a transparent conducting layer on a planar and untextured crystalline p-n silicon solar cell. A high-quality monolayer graphene with 97% transparency and 350 Ω/□ sheet resistance grown by atmospheric pressure chemical vapor deposition method was transferred onto planar Si cells. An increase in efficiency from 5.38% to 7.85% was observed upon deposition of graphene onto Si cells, which further increases to 8.94% upon SiO2 deposition onto the graphene/Si structure. A large increase in photon conversion efficiency as a result of graphene deposition shows that the electronic interaction and the presence of an electric field at the graphene/Si interface together play an important role in this improvement and additionally lead to a reduction in series resistance due to the conducting nature of graphene.

Eddy current imaging for electrical characterization of silicon solar cells and TCO layers

NASA Astrophysics Data System (ADS)

Hwang, Byungguk; Hillmann, Susanne; Schulze, Martin; Klein, Marcus; Heuer, Henning

2015-03-01

Eddy Current Testing has been mainly used to determine defects of conductive materials and wall thicknesses in heavy industries such as construction or aerospace. Recently, high frequency Eddy Current imaging technology was developed. This enables the acquirement of information of different depth level in conductive thin-film structures by realizing proper standard penetration depth. In this paper, we summarize the state of the art applications focusing on PV industry and extend the analysis implementing achievements by applying spatially resolved Eddy Current Testing. The specific state of frequency and complex phase angle rotation demonstrates diverse defects from front to back side of silicon solar cells and characterizes homogeneity of sheet resistance in Transparent Conductive Oxide (TCO) layers. In order to verify technical feasibility, measurement results from the Multi Parameter Eddy Current Scanner, MPECS are compared to the results from Electroluminescence.

Cellulose nanofibers/reduced graphene oxide flexible transparent conductive paper.

PubMed

Gao, Kezheng; Shao, Ziqiang; Wu, Xue; Wang, Xi; Li, Jia; Zhang, Yunhua; Wang, Wenjun; Wang, Feijun

2013-08-14

The cellulose nanofibers (CNFs) paper exhibit high visible light transmittance, high mechanical strength, and excellent flexibility. Therefore, CNFs paper may be an excellent substrate material for flexible transparent electronic devices. In this paper, we endeavor to prepare CNFs-based flexible transparent conductive paper by layer-by-layer (LbL) assembly using divalent copper ions (Cu(2+)) as the crosslinking agent. The thickness of the reduced graphene oxide (RGO) active layer in the CNFs paper can be controlled by the cycle times of the LbL assembly. CNFs/[RGO]20 paper has the sheet resistances of ∼2.5 kΩ/□, and the transmittance of about 76% at a wavelength of 550 nm. Furthermore, CNFs/[RGO]20 paper inherits the excellent mechanical properties of CNFs paper, and the ultimate strength is about 136 MPa. CNFs-based flexible transparent conductive paper also exhibits excellent electrical stability and flexibility. Copyright © 2013. Published by Elsevier Ltd.

Large patternable metal nanoparticle sheets by photo/e-beam lithography

NASA Astrophysics Data System (ADS)

Saito, Noboru; Wang, Pangpang; Okamoto, Koichi; Ryuzaki, Sou; Tamada, Kaoru

2017-10-01

Techniques for micro/nano-scale patterning of large metal nanoparticle sheets can potentially be used to realize high-performance photoelectronic devices because the sheets provide greatly enhanced electrical fields around the nanoparticles due to localized surface plasmon resonances. However, no single metal nanoparticle sheet currently exists with sufficient durability for conventional lithographical processes. Here, we report large photo and/or e-beam lithographic patternable metal nanoparticle sheets with improved durability by incorporating molecular cross-linked structures between nanoparticles. The cross-linked structures were easily formed by a one-step chemical reaction; immersing a single nanoparticle sheet consisting of core metals, to which capping molecules ionically bond, in a dithiol ethanol solution. The ligand exchange reaction processes were discussed in detail, and we demonstrated 20 μm wide line and space patterns, and a 170 nm wide line of the silver nanoparticle sheets.

Nanofabrication and Nanopatterning of Carbon Nanomaterials for Flexible Electronics

NASA Astrophysics Data System (ADS)

Ding, Junjun

Stretchable electrodes have increasingly drawn attention as a vital component for flexible electronic devices. Carbon nanomaterials such as graphene and carbon nanotubes (CNTs) exhibit properties such as high mechanical flexibility and strength, optical transparency, and electrical conductivity which are naturally required for stretchable electrodes. Graphene growth, nanopatterning, and transfer processes are important steps to use graphene as flexible electrodes. However, advances in the large-area nanofabrication and nanopatterning of carbon nanomaterials such as graphene are necessary to realize the full potential of this technology. In particular, laser interference lithography (LIL), a fast and low cost large-area nanoscale patterning technique, shows tremendous promise for the patterning of graphene and other nanostructures for numerous applications. First, it was demonstrated that large-area nanopatterning and the transfer of chemical vapor deposition (CVD) grown graphene via LIL and plasma etching provide a reliable method to provide large area nanoengineered graphene on various target substrates. Then, to improve the electrode performance under large strain (naturally CVD grown graphene sheet will crack at tensile strains larger than 1%), a corrugated graphene structure on PDMS was designed, fabricated, and tested, with experimental results indicating that this approach successfully allows the graphene sheets to withstand cyclic tensile strains up to 15%. Lastly, to further enhance the performance of carbon-based stretchable electrodes, an approach was developed which coupled graphene and vertically aligned CNT (VACNT) on a flexible PDMS substrate. Characterization of the graphene-VACNT hybrid shows high electrical conductivity and durability through 50 cycles of loading up to 100% tensile strain. While flexible electronics promise tremendous advances in important technological areas such as healthcare, sensing, energy, and wearable electronics, continued advances in the nanofabrication, nanopatterning, and transfer of carbon nanomaterials such as those pursued here are necessary to fully realize this vision.

Hybrid graphene electrodes for supercapacitors of high energy density

NASA Astrophysics Data System (ADS)

Zhang, Feifei; Tang, Jie; Shinya, Norio; Qin, Lu-Chang

2013-10-01

We describe a process of co-reduction to reduce dispersed graphene oxide (GO) and single-walled carbon nanotubes (SWNTs) simultaneously for preparation of hybrid electrodes for graphene supercapacitors. The SWNTs are in between the inter-layer space of graphene sheets as a spacer to prevent effectively restacking of graphene that often limits seriously the electrochemical performance of graphene supercapacitors. The SWNTs also act as conductive binders to improve the electrical conduction of the electrode. A high specific capacitance of 261 F g-1 for a single electrode and specific energy density of 123 W h kg-1 measured in the two-electrode configuration have been obtained in ionic liquid (EMI-TFSI). For interpretation of color in Fig. 6, the reader is referred to the web version of this article.

Effect of Hydrogen Post-Annealing on Transparent Conductive ITO/Ga2O3 Bi-Layer Films for Deep Ultraviolet Light-Emitting Diodes.

PubMed

Kim, Kyeong Heon; Kim, Su Jin; Park, Sang Young; Kim, Tae Geun

2015-10-01

The effect of hydrogen post-annealing on the electrical and optical properties of ITO/Ga2O bi-layer films, deposited by RF magnetron sputtering, is investigated for potential applications to transparent conductive electrodes of ultraviolet (UV) light-emitting diodes. Three samples--an as-deposited sample and two samples post-annealed in N2 gas and N2-H2 gas mixture--were prepared and annealed at different temperatures ranging from 100 °C to 500 °C for comparison. Among these samples, the sample annealed at 300 °C in a mixture of N2 and H2 gases shows the lowest sheet resistance of 301.3 Ω/square and a high UV transmittance of 87.1% at 300 nm.

Enhancing workability in sheet production of high silicon content electrical steel through large shear deformation

DOE PAGES

Kustas, Andrew B.; Johnson, David R.; Trumble, Kevin P.; ...

2018-07-01

Enhanced workability, as characterized by the magnitude and heterogeneity of accommodated plastic strains during sheet processing, is demonstrated in high Si content Fe-Si alloys containing 4 and 6.5 wt% Si using two single-step, simple-shear deformation techniques – peeling and large strain extrusion machining (LSEM). The model Fe-Si material system was selected for its intrinsically poor material workability, and well-known applications potential in next-generation electric machines. In a comparative study of the deformation characteristics of the shear processes with conventional rolling, two distinct manifestations of workability are observed. For rolling, the relatively diffuse and unconfined deformation zone geometry leads to crackingmore » at low strains, with sheet structures characterized by extensive deformation twinning and banding. Workpiece pre-heating is required to improve the workability in rolling. In contrast, peeling and LSEM produce continuous sheet at large plastic strains without cracking, the result of more confined deformation geometries that enhances the workability. Peeling, however, results in heterogeneous, shear-banded microstructures, pointing to a second type of workability issue – flow localization – that limits sheet processing. This shear banding is to a large extent facilitated by unrestricted flow at the sheet surface, unavoidable in peeling. With additional confinement of this free surface deformation and appropriately designed deformation zone geometry, LSEM is shown to suppress shear banding, resulting in continuous sheet with homogeneous microstructure. Thus LSEM is shown to produce the greatest enhancement in process workability for producing sheet. In conclusion, these workability findings are explained and discussed based on differences in process mechanics and deformation zone geometry.« less

Enhancing workability in sheet production of high silicon content electrical steel through large shear deformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kustas, Andrew B.; Johnson, David R.; Trumble, Kevin P.

Enhanced workability, as characterized by the magnitude and heterogeneity of accommodated plastic strains during sheet processing, is demonstrated in high Si content Fe-Si alloys containing 4 and 6.5 wt% Si using two single-step, simple-shear deformation techniques – peeling and large strain extrusion machining (LSEM). The model Fe-Si material system was selected for its intrinsically poor material workability, and well-known applications potential in next-generation electric machines. In a comparative study of the deformation characteristics of the shear processes with conventional rolling, two distinct manifestations of workability are observed. For rolling, the relatively diffuse and unconfined deformation zone geometry leads to crackingmore » at low strains, with sheet structures characterized by extensive deformation twinning and banding. Workpiece pre-heating is required to improve the workability in rolling. In contrast, peeling and LSEM produce continuous sheet at large plastic strains without cracking, the result of more confined deformation geometries that enhances the workability. Peeling, however, results in heterogeneous, shear-banded microstructures, pointing to a second type of workability issue – flow localization – that limits sheet processing. This shear banding is to a large extent facilitated by unrestricted flow at the sheet surface, unavoidable in peeling. With additional confinement of this free surface deformation and appropriately designed deformation zone geometry, LSEM is shown to suppress shear banding, resulting in continuous sheet with homogeneous microstructure. Thus LSEM is shown to produce the greatest enhancement in process workability for producing sheet. In conclusion, these workability findings are explained and discussed based on differences in process mechanics and deformation zone geometry.« less

Effect of Precipitating Electrons on Stormtime Inner Magnetospheric Electric Fields during the 17 March 2013 Storm

NASA Astrophysics Data System (ADS)

Chen, M.; Lemon, C. L.; Sazykin, S. Y.; Wolf, R.; Hecht, J. H.; Walterscheid, R. L.; Boyd, A. J.; Turner, D. L.

2015-12-01

We investigate how scattering of electrons by waves in the plasma sheet and plasmasphere affects precipitating energy flux distributions and how the precipitating electrons modify the ionospheric conductivity and electric potentials during the large 17 March 2013 magnetic storm. Of particular interest is how electron precipitation in the evening sector affects the development of the Sub-auroral Polarization Stream (SAPS) electric field that is observed at sub-auroral latitudes in that sector. Our approach is to use the magnetically and electrically self-consistent Rice Convection Model - Equilibrium (RCM-E) of the inner magnetosphere to simulate the stormtime precipitating electron distributions and the electric field. We use parameterized rates of whistler-generated electron pitch-angle scattering from Orlova and Shprits [JGR, 2014] that depend on equatorial radial distance, magnetic activity (Kp), and magnetic local time (MLT) outside the simulated plasmasphere. Inside the plasmasphere, parameterized scattering rates due to hiss [Orlova et al., GRL, 2014] are used. We compare simulated trapped and precipitating electron flux distributions with measurements from Van Allen Probes/MagEIS, POES/TED and MEPED, respectively, to validate the electron loss model. Ground-based (SuperDARN) and in-situ (Van Allen Probes/EFW) observations of electric fields are compared with the simulation results. We discuss the effect of precipitating electrons on the SAPS and inner magnetospheric electric field through the data-model comparisons.

Preparation of graphene foam with high performance by modified self-assembly method

NASA Astrophysics Data System (ADS)

Zhang, Wenhui; Sun, Youyi; Liu, Tantan; Li, Diansen; Hou, Chunlin; Gao, Li; Liu, Yaqing

2016-03-01

Recently, self-assembly method was applied for preparation of graphene foam. However, it is still a great challenge to obtain a three-dimensional graphene network with high performance (e.g., low density, high mechanical strength and high conductivity together) for the self-assembly method. Herein, a modified self-assembly method applied for preparation of graphene foam was investigated, in which, L-ascorbic acid and HI were firstly chosen as the reducing agent, and further reduced by hydrazine hydrate. The results demonstrated that the graphene foam showed high compressive strength (ca. 320 kPa), high electrical conductivity (20.6 S/m) and low density (14.7 mg/cm-1). Especially, the obtained compressive strength (ca. 320 kPa) is the highest value compared to the data of graphene foam reported in previous works. This phenomenon may be due to following three reasons: (1) the reaction between hydrazine hydrate and graphene brought some covalent bonds among graphene sheets; (2) graphene foam was achieved by high hydrophobicity and electrostatic repulsion which inhibit the restacking of graphene sheets; (3) the removal of the oxygen groups by hydrazine hydrate efficiently restores conjugation of sp2 regions and the π-π interaction in the cross-linking sites, which tightly bonds the sheets together. The obtained graphene foam not only had good porous structure and mechanical strength, but also showed excellent satisfactory double-layer capacitive behavior with good electrochemical cyclic stability and high specific capacitance of 171.0 F/g for application in electrode of supercapacitors and absorption capacities for the removal of various oils and dyes from water.

Engineering Nanostructures by Decorating Magnetic Nanoparticles onto Graphene Oxide Sheets to Shield Electromagnetic Radiations.

PubMed

Mural, Prasanna Kumar S; Pawar, Shital Patangrao; Jayanthi, Swetha; Madras, Giridhar; Sood, Ajay K; Bose, Suryasarathi

2015-08-05

In this study, a minimum reflection loss of -70 dB was achieved for a 6 mm thick shield (at 17.1 GHz frequency) employing a unique approach. This was accomplished by engineering nanostructures through decoration of magnetic nanoparticles (nickel, Ni) onto graphene oxide (GO) sheets. Enhanced electromagnetic (EM) shielding was derived by selectively localizing the nanoscopic particles in a specific phase of polyethylene (PE)/poly(ethylene oxide) (PEO) blends. By introduction of a conducting inclusion (like multiwall carbon nanotubes, MWNTs) together with the engineered nanostructures (nickel-decorated GO, GO-Ni), the shielding efficiency can be enhanced significantly in contrast to physically mixing the particles in the blends. For instance, the composites showed a shielding efficiency >25 dB for a combination of MWNTs (3 wt %) and Ni nanoparticles (52 wt %) in PE/PEO blends. However, similar shielding effectiveness could be achieved for a combination of MWNTs (3 wt %) and 10 vol % of GO-Ni where in the effective concentration of Ni was only 19 wt %. The GO-Ni sheets facilitated in an efficient charge transfer as manifested from high electrical conductivity in the blends besides enhancing the permeability in the blends. It is envisioned that GO is simultaneously reduced in the process of synthesizing GO-Ni, and this facilitated in efficient charge transfer between the neighboring CNTs. More interestingly, the blends with MWNTs/GO-Ni attenuated the incoming EM radiation mostly by absorption. This study opens new avenues in designing polyolefin-based lightweight shielding materials by engineering nanostructures for numerous applications.

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, S.P.; Chamberlin, R.

1997-10-07

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells. 13 figs.

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, Scot P.; Chamberlin, Rhodes

1999-02-09

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells.

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, S.P.; Chamberlin, R.

1999-02-09

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells. 13 figs.

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, Scot P.; Chamberlin, Rhodes

1997-10-07

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells.

Nonlocal thermal transport across embedded few-layer graphene sheets

DOE PAGES

Liu, Ying; Huxtable, Scott T.; Yang, Bao; ...

2014-11-13

Thermal transport across the interfaces between few-layer graphene sheets and soft materials exhibits intriguing anomalies when interpreted using the classical Kapitza model, e.g., the conductance of the same interface differs greatly for different modes of interfacial thermal transport. Using atomistic simulations, we show that such thermal transport follows a nonlocal flux-temperature drop constitutive law and is characterized jointly by a quasi-local conductance and a nonlocal conductance instead of the classical Kapitza conductance. Lastly, the nonlocal model enables rationalization of many anomalies of the thermal transport across embedded few-layer graphene sheets and should be used in studies of interfacial thermal transportmore » involving few-layer graphene sheets or other ultra-thin layered materials.« less

Use of a spread sheet to calculate the current-density distribution produced in human and rat models by low-frequency electric fields.

PubMed

Hart, F X

1990-01-01

The current-density distribution produced inside irregularly shaped, homogeneous human and rat models by low-frequency electric fields is obtained by a two-stage finite-difference procedure. In the first stage the model is assumed to be equipotential. Laplace's equation is solved by iteration in the external region to obtain the capacitive-current densities at the model's surface elements. These values then provide the boundary conditions for the second-stage relaxation solution, which yields the internal current-density distribution. Calculations were performed with the Excel spread-sheet program on a Macintosh-II microcomputer. A spread sheet is a two-dimensional array of cells. Each cell of the sheet can represent a square element of space. Equations relating the values of the cells can represent the relationships between the potentials in the corresponding spatial elements. Extension to three dimensions is readily made. Good agreement was obtained with current densities measured on human models with both, one, or no legs grounded and on rat models in four different grounding configurations. The results also compared well with predictions of more sophisticated numerical analyses. Spread sheets can provide an inexpensive and relatively simple means to perform good, approximate dosimetric calculations on irregularly shaped objects.

Imaging Neuronal Seal Resistance on Silicon Chip using Fluorescent Voltage-Sensitive Dye

PubMed Central

Braun, Dieter; Fromherz, Peter

2004-01-01

The electrical sheet resistance between living cells grown on planar electronic contacts of semiconductors or metals is a crucial parameter for bioelectronic devices. It determines the strength of electrical signal transduction from cells to chips and from chips to cells. We measured the sheet resistance by applying AC voltage to oxidized silicon chips and by imaging the voltage change across the attached cell membrane with a fluorescent voltage-sensitive dye. The phase map of voltage change was fitted with a planar core-coat conductor model using the sheet resistance as a free parameter. For nerve cells from rat brain on polylysine as well as for HEK293 cells and MDCK cells on fibronectin we find a similar sheet resistance of 10 MΩ. Taking into account the independently measured distance of 50 nm between chip and membrane for these cells, we obtain a specific resistance of 50 Ωcm that is indistinguishable from bulk electrolyte. On the other hand, the sheet resistance for erythrocytes on polylysine is far higher, at ∼1.5 GΩ. Considering the distance of 10 nm, the specific resistance in the narrow cleft is enhanced to 1500 Ωcm. We find this novel optical method to be a convenient tool to optimize the interface between cells and chips for bioelectronic devices. PMID:15298937

Imaging neuronal seal resistance on silicon chip using fluorescent voltage-sensitive dye.

PubMed

Braun, Dieter; Fromherz, Peter

2004-08-01

The electrical sheet resistance between living cells grown on planar electronic contacts of semiconductors or metals is a crucial parameter for bioelectronic devices. It determines the strength of electrical signal transduction from cells to chips and from chips to cells. We measured the sheet resistance by applying AC voltage to oxidized silicon chips and by imaging the voltage change across the attached cell membrane with a fluorescent voltage-sensitive dye. The phase map of voltage change was fitted with a planar core-coat conductor model using the sheet resistance as a free parameter. For nerve cells from rat brain on polylysine as well as for HEK293 cells and MDCK cells on fibronectin we find a similar sheet resistance of 10 MOmega. Taking into account the independently measured distance of 50 nm between chip and membrane for these cells, we obtain a specific resistance of 50 Omegacm that is indistinguishable from bulk electrolyte. On the other hand, the sheet resistance for erythrocytes on polylysine is far higher, at approximately 1.5 GOmega. Considering the distance of 10 nm, the specific resistance in the narrow cleft is enhanced to 1500 Omegacm. We find this novel optical method to be a convenient tool to optimize the interface between cells and chips for bioelectronic devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woltornist, Steven J.; Carrillo, Jan-Michael Y.; Xu, Thomas O.

The unique electrical, thermal, and mechanical properties of graphene make it a perfect candidate for applications in graphene/graphite based polymer composites, yet challenges due to the lack of solubility of pristine graphene/graphite in water and common organic solvents have limited its practical utilization. In this paper, we report a scalable and environmentally friendly technique to form water-in-oil type emulsions stabilized by overlapping pristine graphene sheets, enabling the synthesis of open cell foams containing a continuous graphitic network. Our approach utilizes the insolubility of graphene/graphite in both water and organic solvents and so does not require oxidation, reduction, surfactants, high boilingmore » solvents, chemical functionalization, or the input of large amounts of mechanical energy or heat. At the heart of our technique is the strong attraction of graphene to high-energy oil and water interfaces. This allows for the creation of stable water-in-oil emulsions with controlled droplet size and overlapping graphene sheets playing the role of surfactant by covering the droplet surface and stabilizing the interfaces with a thin graphitic skin. Finally, these emulsions are used as templates for the synthesis of open cell foams with densities below 0.35 g/cm 3 that exhibit remarkable mechanical and electrical properties including compressive moduli up to ~100 MPa, compressive strengths of over 8.3 MPa (1200 psi), and bulk conductivities approaching 7 S/m.« less

Rational Design of 1-D Co3O4 Nanofibers@Low content Graphene Composite Anode for High Performance Li-Ion Batteries

PubMed Central

Cho, Su-Ho; Jung, Ji-Won; Kim, Chanhoon; Kim, Il-Doo

2017-01-01

Cobalt oxide that has high energy density, is the next-generation candidate as the anode material for LIBs. However, the practical use of Co3O4 as anode material has been hindered by limitations, especially, low electrical conductivity and pulverization from large volume change upon cycling. These features lead to hindrance to its electrochemical properties for lithium-ion batteries. To improve electrochemical properties, we synthesized one-dimensional (1-D) Co3O4 nanofibers (NFs) overed with reduced graphene oxide (rGO) sheets by electrostatic self-assembly (Co3O4 NFs@rGO). The flexible graphene oxide sheets not only prevent volume changes of active materials upon cycling as a clamping layer but also provide efficient electrical pathways by three-dimensional (3-D) network architecture. When applied as an anode for LIBs, the Co3O4 NFs@rGO exhibits superior electrochemical performance: (i) high reversible capacity (615 mAh g−1 and 92% capacity retention after 400 cycles at 4.0 A g−1) and (ii) excellent rate capability. Herein, we highlighted that the enhanced conversion reaction of the Co3O4 NFs@rGO is attributed to effective combination of 1-D nanostructure and low content of rGO (~3.5 wt%) in hybrid composite. PMID:28345589

Removal of virus and toxin using heatable multi-walled carbon nanotube web filters

NASA Astrophysics Data System (ADS)

Jang, Hoon-Sik; Jeon, Sang Koo; Ryu, Kwon-Sang; Nahm, Seung Hoon

2016-02-01

Many studies have used a carbon nanotube (CNT) filter for pathogen removal and/or inactivation by means of electrochemical or electrochlorination. The large surface area, fine pore size and high electrical and thermal conductivity of CNTs make them suitable and distinct to use for the filtering and removal of pathogens. Here, we grew spin-capable multi-walled CNTs (MWCNTs) and manufactured a web filter using the spun MWCNTs. Botulinum toxin type E light chain (BoT/E-LC) and vaccinia virus (VV) were filtered using the MWCNT web filters and were evaporated and removed by applying direct current (DC) voltage to both sides of the MWCNT webs, excluding electrochemical or electrochlorination. The filtering and removal of BoT/E-LC and VV were performed after seven layers of the MWCNT sheets were coated onto a silicon oxide porous plate. The electrical resistance of the webs in the seven layer sheet was 293 Ω. The temperature of MWCNTs webs was linearly increased to ˜300 °C at 210 V of DC voltage. This temperature was enough to remove BoT/E-LC and VV. From the SEM and XPS results, we confirmed that BoT/E-LC and VV on the MWCNT webs were almost removed by applying a DC voltage and that some element (N, Na, Cl, etc.) as residues on the MWCNT webs remained.

Commercial Vehicle Technology Evaluation Publications | Transportation

Science.gov Websites

Research | NREL Commercial Vehicle Technology Evaluation Publications Commercial Vehicle Technology Evaluation Publications NREL publishes technical reports, fact sheets, and other documents about its fleet evaluation activities: Hybrid electric vehicle publications Electric and plug-in hybrid

49. OUTLET WORKS: THREE TON CRANE, ELECTRICAL SYSTEM NO 4. ...

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

49. OUTLET WORKS: THREE TON CRANE, ELECTRICAL SYSTEM NO 4. Sheet H-4, December 12, 1939. File no. SA 342/60. - Prado Dam, Outlet Works, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

Laser Processing of Carbon Nanotube Transparent Conducting Films

NASA Astrophysics Data System (ADS)

Mann, Andrew

Transparent conducting films, or TCFs, are 2D electrical conductors with the ability to transmit light. Because of this, they are used in many popular electronics including smart phones, tablets, solar panels, and televisions. The most common material used as a TCF is indium tin oxide, or ITO. Although ITO has great electrical and optical characteristics, it is expensive, brittle, and difficult to pattern. These limitations have led researchers toward other materials for the next generation of displays and touch panels. The most promising material for next generation TCFs is carbon nanotubes, or CNTs. CNTs are cylindrical tubes of carbon no more than a few atoms thick. They have different electrical and optical properties depending on their atomic structure, and are extremely strong. As an electrode, they conduct electricity through an array of randomly dispersed tubes. The array is highly transparent because of gaps between the tubes, and size and optical properties of the CNTs. Many research groups have tried making CNT TCFs with opto-electric properties similar to ITO but have difficultly achieving high conductivity. This is partly attributed to impurities from fabrication and a mix of different tube types, but is mainly caused by low junction conductivity. In functionalized nanotubes, junction conductivity is impaired by covalently bonded molecules added to the sidewalls of the tubes. The addition of this molecule, known as functionalization, is designed to facilitate CNT dispersion in a solvent by adding properties of the molecule to the CNTs. While necessary for a good solution, functionalization decreases the conductivity in the CNT array by creating defects in the tube's structures and preventing direct inter-carbon bonding. This research investigates removing the functional coating (after tube deposition) by laser processing. Laser light is able to preferentially heat the CNTs because of their optical and electrical properties. Through local conduction, the relatively weak functional molecules are thermally decomposed. This restores the pristine CNT structure and allows carbon to carbon bonds to form; thereby significantly improving the junction and sheet conductivity. Laser processing is performed without damaging the TCF substrate (usually glass or PET) because laser light is not absorbed by the substrate and conduction from the CNTs is limited. In addition to removing the functional coating, laser light improves the electrical conductivity by purifying the CNT array. The purity is improved through the ablation of defective tubes and amorphous carbon in the CNT film.[1] Using higher laser power, it is possible to locally remove the CNTs. Selective laser removal of the CNTs is a dry process that can be used to pattern the electrode. This is a much simpler and less expensive patterning technique than wet acid etching used for ITO. In summary, laser processing of CNT TCFs is shown to improve the electrical conductivity by defunctionalizing the CNTs. In addition, laser exposure increases purity by removing defects and can be used to pattern the electrode. These advances make CNTs more competitive as an alternative for ITO which has both cost and performance limitations. [1] T. Ueda, S. K. (2008). Effect of laser irradiation on carbon nanotube films for NOx gas sensor. Surface & Coatings Technology, 202, 5325--5328.

An Anisotropic Model for Magnetostriction and Magnetization Computing for Noise Generation in Electric Devices.

PubMed

Mbengue, Serigne Saliou; Buiron, Nicolas; Lanfranchi, Vincent

2016-04-16

During the manufacturing process and use of ferromagnetic sheets, operations such as rolling, cutting, and tightening induce anisotropy that changes the material's behavior. Consequently for more accuracy in magnetization and magnetostriction calculations in electric devices such as transformers, anisotropic effects should be considered. In the following sections, we give an overview of a macroscopic model which takes into account the magnetic and magnetoelastic anisotropy of the material for both magnetization and magnetostriction computing. Firstly, a comparison between the model results and measurements from a Single Sheet Tester (SST) and values will be shown. Secondly, the model is integrated in a finite elements code to predict magnetostrictive deformation of an in-house test bench which is a stack of 40 sheets glued together by the Vacuum-Pressure Impregnation (VPI) method. Measurements on the test bench and Finite Elements results are presented.

High performance ZnO:Al films deposited on PET substrates using facing target sputtering

NASA Astrophysics Data System (ADS)

Guo, Tingting; Dong, Guobo; Gao, Fangyuan; Xiao, Yu; Chen, Qiang; Diao, Xungang

2013-10-01

ZnO:Al (ZAO) thin films have been deposited on flexible PET substrates using a plasma damage-free facing target sputtering system at room temperature. The structure, surface morphology, electrical and optical properties were investigated as a function of working power. All the samples have a highly preferred orientation of the c-axis perpendicular to the PET substrate and have a high quality surface. With increased working power, the carrier concentration changes slightly, the mobility increases at the beginning and decreases after it reaches a maximum value, in line with electrical conductivity. The figure of merit has been significantly improved with increasing of the working power. Under the optimized condition, the lowest resistivity of 1.3 × 10-3 Ω cm with a sheet resistance of 29 Ω/□ and the relative visible transmittance above 93% in the visible region were obtained.

Thin and long silver nanowires self-assembled in ionic liquids as a soft template: electrical and optical properties

PubMed Central

2014-01-01

Thin and long silver nanowires were successfully synthesized using the polyvinylpyrrolidone (PVP)-assisted polyol method in the presence of ionic liquids, tetrapropylammonium chloride and tetrapropylammonium bromide, which served as soft template salts. The first step involved the formation of Ag nanoparticles with a diameter of 40 to 50 nm through the reduction of silver nitrate. At the growing stage, the Ag nanoparticles were converted into thin and long one-dimensional wires, with uniform diameters of 30 ± 3 nm and lengths of up to 50 μm. These Ag nanowires showed an electrical conductivity of 0.3 × 105 S/cm, while the sheet resistance of a two-dimensional percolating Ag nanowire network exhibited a value of 20 Ω/sq with an optical transmittance of 93% and a low haze value. PMID:25024690

Thin and long silver nanowires self-assembled in ionic liquids as a soft template: electrical and optical properties.

PubMed

Chang, Min-Hwa; Cho, Hyun-Ah; Kim, Youn-Soo; Lee, Eun-Jong; Kim, Jin-Yeol

2014-01-01

Thin and long silver nanowires were successfully synthesized using the polyvinylpyrrolidone (PVP)-assisted polyol method in the presence of ionic liquids, tetrapropylammonium chloride and tetrapropylammonium bromide, which served as soft template salts. The first step involved the formation of Ag nanoparticles with a diameter of 40 to 50 nm through the reduction of silver nitrate. At the growing stage, the Ag nanoparticles were converted into thin and long one-dimensional wires, with uniform diameters of 30 ± 3 nm and lengths of up to 50 μm. These Ag nanowires showed an electrical conductivity of 0.3 × 10(5) S/cm, while the sheet resistance of a two-dimensional percolating Ag nanowire network exhibited a value of 20 Ω/sq with an optical transmittance of 93% and a low haze value.

A current disruption mechanism in the neutral sheet for triggering substorm expansions

NASA Technical Reports Server (NTRS)

Lui, A. T. Y.; Mankofsky, A.; Chang, C.-L.; Papadopoulos, K.; Wu, C. S.

1989-01-01

Two main areas were addressed in support of an effort to understand mechanism responsible for the broadband electrostatic noise (BEN) observed in the magnetotail. The first area concerns the generation of BEN in the boundary layer region of the magnetotail whereas the second area concerns the occassional presence of BEN in the neutral sheet region. For the generation of BEN in the boundary layer region, a hybrid simulation code was developed to perform reliable longtime, quiet, highly resolved simulations of field aligned electron and ion beam flow. The result of the simulation shows that broadband emissions cannot be generated by beam-plasma instability if realistic values of the ion beam parameters are used. The waves generated from beam-plasma instability are highly discrete and are of high frequencies. For the plasma sheet boundary layer condition, the wave frequencies are in the kHz range, which is incompatible with the observation that the peak power in BEN occur in the 10's of Hz range. It was found that the BEN characteristics are more consistent with lower hybrid drift instability. For the occasional presence of BEN in the neutral sheet region, a linear analysis of the kinetic cross-field streaming instability appropriate to the neutral sheet condition just prior to onset of substorm expansion was performed. By solving numerically the dispersion relation, it was found that the instability has a growth time comparable to the onset time scale of substorm onset. The excited waves have a mixed polarization in the lower hybrid frequency range. The imposed drift driving the instability corresponds to unmagnetized ions undergoing current sheet acceleration in the presence of a cross-tail electric field. The required electric field strength is in the 10 mV/m range which is well within the observed electric field values detected in the neutral sheet during substorms. This finding can potentially account for the disruption of cross-tail current and its diversion to the ionosphere to form the substorm current wedge. Furthermore, a number of features associated with substorm expansion onset can be understood based on this substorm onset scenario.

278. Photocopy of drawing (1978 structural electrical drawing by the ...

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

278. Photocopy of drawing (1978 structural electrical drawing by the Space and Missile Test Center, VAFB, USAF) DETAILS, SECTION, AND ELECTRICAL PLAN FOR THE TIROS AND NOAA THEODOLITE STATION, SLC-3E, SHEET 4 OF 4 - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

Military Curriculum Materials for Vocational and Technical Education. Fundamentals of Electricity, 3-7.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. National Center for Research in Vocational Education.

This self-paced correspondence course for independent study in electricity was adapted from military curriculum materials for use in vocational education. This basic course is designed to provide the student with some fundamentals of electricity--not with specific job skills. The seven lessons of the course each have a lesson assignment sheet with…

3D Graphene-Ni Foam as an Advanced Electrode for High-Performance Nonaqueous Redox Flow Batteries.

PubMed

Lee, Kyubin; Lee, Jungkuk; Kwon, Kyoung Woo; Park, Min-Sik; Hwang, Jin-Ha; Kim, Ki Jae

2017-07-12

Electrodes composed of multilayered graphene grown on a metal foam (GMF) were prepared by directly growing multilayer graphene sheets on a three-dimensional (3D) Ni-foam substrate via a self-catalyzing chemical vapor deposition process. The multilayer graphene sheets are successfully grown on the Ni-foam substrate surface, maintaining the unique 3D macroporous structure of the Ni foam. The potential use of GMF electrodes in nonaqueous redox flow batteries (RFBs) is carefully examined using [Co(bpy) 3 ] +/2+ and [Fe(bpy) 3 ] 2+/3+ redox couples. The GMF electrodes display a much improved electrochemical activity and enhanced kinetics toward the [Co(bpy) 3 ] +/2+ (anolyte) and [Fe(bpy) 3 ] 2+/3+ (catholyte) redox couples, compared with the bare Ni metal foam electrodes, suggesting that the 2D graphene sheets having lots of interdomain defects provide sufficient reaction sites and secure electric-conduction pathways. Consequently, a nonaqueous RFB cell assembled with GMF electrodes exhibits high Coulombic and voltage efficiencies of 87.2 and 90.9%, respectively, at the first cycle. This performance can be maintained up to the 50th cycle without significant efficiency loss. Moreover, the importance of a rational electrode design for improving electrochemical performance is addressed.

Field evaluation of ZeroFly--an insecticide incorporated plastic sheeting against malaria vectors & its impact on malaria transmission in tribal area of northern Orissa.

PubMed

Sharma, S K; Upadhyay, A K; Haque, M A; Tyagi, P K; Mohanty, S S; Mittal, P K; Dash, A P

2009-10-01

Insecticide incorporated plastic sheeting is a new technology to control mosquitoes in emergency shelter places and also temporary habitations in different locations. Therefore, field studies were conducted to assess the efficacy of ZeroFly plastic sheeting treated with deltamethrin on prevailing disease vectors Anopheles culicifacies and An. fluviatilis and its impact on malaria transmission in one of the highly endemic areas of Orissa. The study was conducted in Birkera block of Sundargarh district, Orissa state. The study area comprised 3 villages, which were randomized as ZeroFly plastic sheet, untreated plastic sheet and no sheet area. ZeroFly plastic sheets and untreated plastic sheets were fixed in study and control villages respectively covering all the rooms in each household. Longitudinal studies were conducted on the bioefficacy with the help of cone bioassays, monitoring of the mosquito density through hand catch, floor sheet and exit trap collections and fortnightly domiciliary active surveillance in all the study villages. In ZeroFly plastic sheeting area, there was a significant reduction of 84.7 per cent in the entry rate of total mosquitoes in comparison to pre-intervention phase. There was 56.2 per cent immediate mortality in total mosquitoes in houses with ZeroFly sheeting. The overall feeding success rate of mosquitoes in the trial village was only 12.5 per cent in comparison to 49.7 and 51.1 per cent in villages with untreated plastic sheet and no sheet respectively. There was a significant reduction of 65.0 and 70.5 per cent in malaria incidence in ZeroFly plastic sheeting area as compared to untreated plastic sheet and no sheet area respectively. Our study showed that introduction of ZeroFly plastic sheets in a community-based intervention programme is operationally feasible to contain malaria especially in the high transmission difficult areas.

Characteristics of DC electric fields at dipolarization fronts

NASA Astrophysics Data System (ADS)

Laakso, Harri; Escoubet, Philippe; Masson, Arnaud

2016-04-01

We investigate the characteristics of DC electric field at dipolarization fronts and BBF's using multi-point Cluster observations. There are plenty of important issues that are considered, such as what kind of DC electric fields exist in such events and what are their spatial scales. One can also recognize if electrons and ions perform ExB drift motions in these events. To investigate this, we take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer. The calibrated observations of the three spectrometers are used to determine the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. This investigation also helps understand how well different measurements are calibrated.

The effect of nanowire length and diameter on the properties of transparent, conducting nanowire films

NASA Astrophysics Data System (ADS)

Bergin, Stephen M.; Chen, Yu-Hui; Rathmell, Aaron R.; Charbonneau, Patrick; Li, Zhi-Yuan; Wiley, Benjamin J.

2012-03-01

This article describes how the dimensions of nanowires affect the transmittance and sheet resistance of a random nanowire network. Silver nanowires with independently controlled lengths and diameters were synthesized with a gram-scale polyol synthesis by controlling the reaction temperature and time. Characterization of films composed of nanowires of different lengths but the same diameter enabled the quantification of the effect of length on the conductance and transmittance of silver nanowire films. Finite-difference time-domain calculations were used to determine the effect of nanowire diameter, overlap, and hole size on the transmittance of a nanowire network. For individual nanowires with diameters greater than 50 nm, increasing diameter increases the electrical conductance to optical extinction ratio, but the opposite is true for nanowires with diameters less than this size. Calculations and experimental data show that for a random network of nanowires, decreasing nanowire diameter increases the number density of nanowires at a given transmittance, leading to improved connectivity and conductivity at high transmittance (>90%). This information will facilitate the design of transparent, conducting nanowire films for flexible displays, organic light emitting diodes and thin-film solar cells.This article describes how the dimensions of nanowires affect the transmittance and sheet resistance of a random nanowire network. Silver nanowires with independently controlled lengths and diameters were synthesized with a gram-scale polyol synthesis by controlling the reaction temperature and time. Characterization of films composed of nanowires of different lengths but the same diameter enabled the quantification of the effect of length on the conductance and transmittance of silver nanowire films. Finite-difference time-domain calculations were used to determine the effect of nanowire diameter, overlap, and hole size on the transmittance of a nanowire network. For individual nanowires with diameters greater than 50 nm, increasing diameter increases the electrical conductance to optical extinction ratio, but the opposite is true for nanowires with diameters less than this size. Calculations and experimental data show that for a random network of nanowires, decreasing nanowire diameter increases the number density of nanowires at a given transmittance, leading to improved connectivity and conductivity at high transmittance (>90%). This information will facilitate the design of transparent, conducting nanowire films for flexible displays, organic light emitting diodes and thin-film solar cells. Electronic supplementary information (ESI) available: Includes methods and transmission spectra of nanowire films. See DOI: 10.1039/c2nr30126a

Structural, chemical and electrical characterisation of conductive graphene-polymer composite films

NASA Astrophysics Data System (ADS)

Brennan, Barry; Spencer, Steve J.; Belsey, Natalie A.; Faris, Tsegie; Cronin, Harry; Silva, S. Ravi P.; Sainsbury, Toby; Gilmore, Ian S.; Stoeva, Zlatka; Pollard, Andrew J.

2017-05-01

Graphene poly-acrylic and PEDOT:PSS nanocomposite films were produced using two alternative commercial graphene powders to explore how the graphene flake dimensions and chemical composition affected the electrical performance of the film. A range of analytical techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), were employed to systematically analyse the initial graphene materials as well as the nanocomposite films. Electrical measurements indicated that the sheet resistance of the films was affected by the properties of the graphene flakes used. To further explore the composition of the films, ToF-SIMS mapping was employed and provided a direct means to elucidate the nature of the graphene dispersion in the films and to correlate this with the electrical analysis. These results reveal important implications for how the dispersion of the graphene material in films produced from printable inks can be affected by the type of graphene powder used and the corresponding effect on electrical performance of the nanocomposites. This work provides direct evidence for how accurate and comparable characterisation of the graphene material is required for real-world graphene materials to develop graphene enabled films and proposes a measurement protocol for comparing graphene materials that can be used for international standardisation.

Tunable electrical conductivity in oriented thin films of tetrathiafulvalene-based covalent organic framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, SL; Zhang, YB; Pun, AB

2014-09-16

Despite the high charge-carrier mobility in covalent organic frameworks (COFs), the low intrinsic conductivity and poor solution processability still impose a great challenge for their applications in flexible electronics. We report the growth of oriented thin films of a tetrathiafulvalene-based COF (TTF-COF) and its tunable doping. The porous structure of the crystalline TTF-COF thin film allows the diffusion of dopants such as I-2 and tetracyanoquinodimethane (TCNQ) for redox reactions, while the closely packed 2D grid sheets facilitate the cross-layer delocalization of thus-formed TTF radical cations to generate more conductive mixed-valence TTF species, as is verified by UV-vis-NIR and electron paramagneticmore » resonance spectra. Conductivity as high as 0.28 S m(-1) is observed for the doped COF thin films, which is three orders of magnitude higher than that of the pristine film and is among the highest for COF materials.« less

75 FR 354 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-05

..., 2009. Take notice that the Commission received the following electric rate filings: Docket Numbers...: Iberdrola Renewables, Inc et al. submit Original Sheet 1 to FERC Electric Tariff, Third Revised Volume 1... Maine Power Company. Description: Central Maine Power Company submits executed Engineering and...

Energy Systems Integration: Demonstrating Distributed Resource Communications

DOE Office of Scientific and Technical Information (OSTI.GOV)

2017-01-01

Overview fact sheet about the Electric Power Research Institute (EPRI) and Schneider Electric Integrated Network Testbed for Energy Grid Research and Technology Experimentation (INTEGRATE) project at the Energy Systems Integration Facility. INTEGRATE is part of the U.S. Department of Energy's Grid Modernization Initiative.

Polypropylene/Polyaniline Nanofiber/Reduced Graphene Oxide Nanocomposite with Enhanced Electrical, Dielectric, and Ferroelectric Properties for a High Energy Density Capacitor.

PubMed

Cho, Sunghun; Kim, Minkyu; Lee, Jun Seop; Jang, Jyongsik

2015-10-14

This work demonstrates a ternary nanocomposite system, composed of polypropylene (PP), redoped PANI (r-PANI) nanofibers, and reduced graphene oxides (RGOs), for use in a high energy density capacitor. r-PANI nanofibers were fabricated by the combination methods of chemical oxidation polymerization and secondary doping processes, resulting in higher conductivity (σ≈156 S cm(-1)) than that of the primarily doped PANI nanofibers (σ≈16 S cm(-1)). RGO sheets with high electron mobility and thermal stability can enhance the conductivity of r-PANI/RGO (σ≈220 S cm(-1)) and thermal stability of PP matrix. These findings could be extended to combine the advantages of r-PANI nanofibers and RGO sheets for developing an efficient means of preparing PP/r-PANI/RGO nanocomposite. When the r-PANI/RGO cofillers (10 vol %) were added to PP matrix, the resulting PP/r-PANI/RGO nanocomposite exhibited high dielectric constant (ε'≈51.8) with small dielectric loss (ε″≈9.3×10(-3)). Furthermore, the PP/r-PANI/RGO nanocomposite was used for an energy-harvesting device, which demonstrated high energy density (Ue≈12.6 J cm(-3)) and breakdown strength (E≈5.86×10(3) kV cm(-1)).

Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach

PubMed Central

Kou, Pengfei; Yang, Liu; Chang, Cheng; He, Sailing

2017-01-01

Silver nanowire (Ag NW) networks have attracted wide attention as transparent electrodes for emerging flexible optoelectronics. However, the sheet resistance is greatly limited by large wire-to-wire contact resistances. Here, we propose a simple sunlight illumination approach to remarkably improve their electrical conductivity without any significant degradation of the light transmittance. Because the power density is extremely low (0.1 W/cm2, 1-Sun), only slight welding between Ag NWs has been observed. Despite this, a sheet resistance of <20 Ω/sq and transmittance of ~87% at wavelength of 550 nm as well as excellent mechanical flexibility have still been achieved for Ag NW networks after sunlight illumination for 1 hour or longer, which are significant upgrades over those of ITO. Slight plasmonic welding together with the associated self-limiting effect has been investigated by numerical simulations and further verified experimentally through varied solar concentrations. Due to the reduced resistance, high-performance transparent film heaters as well as efficient defrosters have been demonstrated, which are superior to the previously-reported Ag NW based film heaters. Since the sunlight is environmentally friendly and easily available, sophisticated or expensive facilities are not necessary. Our findings are particularly meaningful and show enormous potential for outdoor applications. PMID:28169343

Transparent, Conductive Coatings Developed for Arc-Proof Solar Arrays

NASA Technical Reports Server (NTRS)

1996-01-01

Transparent, conductive thin-film coatings have many potential applications where a surface must be able to dissipate electrical charges without sacrificing its optical properties. Such applications include automotive and aircraft windows, heat mirrors, optoelectronic devices, gas sensors, and solar cell array surfaces for space applications. Many spacecraft missions require that solar cell array surfaces dissipate charges in order to avoid damage such as electronic upsets, formation of pinholes in the protective coatings on solar array blankets, and contamination due to deposition of sputtered products. In tests at the NASA Lewis Research Center, mixed thin-films of sputter-deposited indium tin oxide (ITO) and magnesium fluoride (MgF2) that could be tailored to the desired sheet resistivity, showed transmittance values of greater than 90 percent. The samples evaluated were composed of mixed, thin-film ITO/MgF2 coatings, with a nominal thickness of 650 angstroms, deposited onto glass substrates. Preliminary results indicated that these coatings were durable to vacuum ultraviolet radiation and atomic oxygen. These coatings show promise for use on solar array surfaces in polar low-Earth-orbit environments, where a sheet resistivity of less than 10(exp 8)/square is required, and in geosynchronous orbit environments, where a resistivity of less than 10(exp 9)/square is required.

Gels as battery separators for soluble electrode cells

NASA Technical Reports Server (NTRS)

Sheibley, D. W.; Gahn, R. F. (Inventor)

1977-01-01

Gels are formed from silica powders and hydrochloric acid. The gels are then impregnated into a polymeric foam and the resultant sheet material is then used in applications where the transport of chloride ions is desired. Specifically disclosed is the utilization of the sheet in electrically rechargeable redox flow cells which find application in bulk power storage systems.

Flexible free-standing TiO2/graphene/PVdF films as anode materials for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Ren, H. M.; Ding, Y. H.; Chang, F. H.; He, X.; Feng, J. Q.; Wang, C. F.; Jiang, Y.; Zhang, P.

2012-12-01

Graphene composites were prepared by hydrothermal method using titanium dioxide (TiO2) adsorbed graphene oxide (GO) sheets as precursors. Free-standing hybrid films for lithium-ion batteries were prepared by adding TiO2/graphene composites to the polyvinylidene fluoride (PVdF)/N-methyl-2-pyrrolidone (NMP) solution, followed by a solvent evaporation technique. These films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and various electrochemical techniques. Flexible films show an excellent cycling performance, which was attributed to the interconnected graphene conducting network, which depressed the increasing of electric resistance during the cycling.

Heating-rate-induced porous α-Fe2O3 with controllable pore size and crystallinity grown on graphene for supercapacitors.

PubMed

Yang, Shuhua; Song, Xuefeng; Zhang, Peng; Gao, Lian

2015-01-14

Porous α-Fe2O3/graphene composites (S-PIGCs) have been synthesized by a simple hydrothermal method combined with a slow annealing route. The S-PIGCs as a supercapacitors electrode material exhibit an ultrahigh specific capacitance of 343.7 F g(-1) at a current density of 3 A g(-1), good rate capability, and excellent cycling stability. The enhanced electrochemical performances are attributed to the combined contribution from the optimally architecture of the porous α-Fe2O3, as a result of a slow annealing, and the extraordinary electrical conductivity of the graphene sheets.

Graphene-wrapped sulfur particles as a rechargeable lithium-sulfur battery cathode material with high capacity and cycling stability.

PubMed

Wang, Hailiang; Yang, Yuan; Liang, Yongye; Robinson, Joshua Tucker; Li, Yanguang; Jackson, Ariel; Cui, Yi; Dai, Hongjie

2011-07-13

We report the synthesis of a graphene-sulfur composite material by wrapping poly(ethylene glycol) (PEG) coated submicrometer sulfur particles with mildly oxidized graphene oxide sheets decorated by carbon black nanoparticles. The PEG and graphene coating layers are important to accommodating volume expansion of the coated sulfur particles during discharge, trapping soluble polysulfide intermediates, and rendering the sulfur particles electrically conducting. The resulting graphene-sulfur composite showed high and stable specific capacities up to ∼600 mAh/g over more than 100 cycles, representing a promising cathode material for rechargeable lithium batteries with high energy density.

Tunable positive and negative refraction of infrared radiation in graphene-dielectric multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, R. Z.; Zhang, Z. M., E-mail: zhuomin.zhang@me.gatech.edu

2015-11-09

Graphene-dielectric multilayers consisting of alternating layers of atom-thick graphene and nanometer-scale dielectric films exhibit characteristics of hyperbolic metamaterials, in which one positive and one negative permittivity are defined for orthogonal directions. Negative permittivity for electric field polarized in the direction parallel to the conductive graphene sheets gives rise to a negative angle of refraction and low-loss transmission for the side-incidence perspective proposed in this work. The Poynting vector tracing demonstrates the switching between positive and negative refraction in the mid-infrared region by tuning the chemical potential of graphene. This adjustable dual-mode metamaterial holds promise for infrared imaging applications.

Self-assembled graphene hydrogel via a one-step hydrothermal process.

PubMed

Xu, Yuxi; Sheng, Kaixuan; Li, Chun; Shi, Gaoquan

2010-07-27

Self-assembly of two-dimensional graphene sheets is an important strategy for producing macroscopic graphene architectures for practical applications, such as thin films and layered paperlike materials. However, construction of graphene self-assembled macrostructures with three-dimensional networks has never been realized. In this paper, we prepared a self-assembled graphene hydrogel (SGH) via a convenient one-step hydrothermal method. The SGH is electrically conductive, mechanically strong, and thermally stable and exhibits a high specific capacitance. The high-performance SGH with inherent biocompatibility of carbon materials is attractive in the fields of biotechnology and electrochemistry, such as drug-delivery, tissue scaffolds, bionic nanocomposites, and supercapacitors.

Pressure dependence of the electro-optic response function in partially exposed polymer dispersed ferroelectric liquid crystals

NASA Technical Reports Server (NTRS)

Parmar, D. S.; Holmes, H. K.

1993-01-01

Ferroelectric liquid crystals in a new configuration, termed partially exposed polymer dispersed ferroelectric liquid crystal (PEPDFLC), respond to external pressures and demonstrate pressure-induced electro-optic switching response. When the PEPDFLC thin film is sandwiched between two transparent conducting electrodes, one a glass plate and the other a flexible sheet such as polyvenylidene fluoride, the switching characteristics of the thin film are a function of the pressure applied to the flexible transparent electrode and the bias voltage across the electrodes. Response time measurements reveal a linear dependence of the change in electric field with external pressure.

Testing of solar cell covers and encapsulants conducted in a simulated space environment

NASA Technical Reports Server (NTRS)

Russell, D. A.

1981-01-01

The materials included in the evaluation were 0211 micro-sheet, FEP-A used as a cover and as an adhesive, DC 93-500 adhesive, PFA "hard coat" used as a cover, GE 615/UV-24 used as a cover, GR 650 used as a cover, and electrostatically bonded 7070 glass. The test environments were 1 MeV electron irradiation interspersed with thermal cycling, 0.5 MeV proton irradiation interspersed with thermal cycling and UV exposure interspersed with thermal cycling. Summary data is given describing the response of the test materials both visually and electrically to the three different environments.

Thermal Properties of Double-Aluminized Kapton at Low Temperatures

NASA Technical Reports Server (NTRS)

Tuttle, J.; DiPirro, M.; Canavan, E.; Hait, T.

2007-01-01

Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to deep space. In order to optimally design such a shield system, it is important to understand the thermal characteristics of DAK down to low temperatures. We describe experiments which measured the thermal conductivity and electrical resistivity down to 4 Kelvin and the emissivity down to 10 Kelvin.

The structure of the plasma sheet-lobe boundary in the Earth's magnetotail

NASA Technical Reports Server (NTRS)

Orsini, S.; Candidi, M.; Formisano, V.; Balsiger, H.; Ghielmetti, A.; Ogilvie, K. W.

1982-01-01

The structure of the magnetotail plasma sheet-plasma lobe boundary was studied by observing the properties of tailward flowing O+ ion beams, detected by the ISEE 2 plasma experiment inside the boundary during three time periods. The computed value of the north-south electric field component as well as the O+ parameters are shown to change at the boundary. The results are related to other observations made in this region. The O+ parameters and the Ez component behavior are shown to be consistent with that expected from the topology of the electric field lines in the tail as mapped from the ionosphere.

Nanodevices for spintronics and methods of using same

DOEpatents

Zaliznyak, Igor; Tsvelik, Alexei; Kharzeev, Dmitri

2013-02-19

Graphene magnet multilayers (GMMs) are employed to facilitate development of spintronic devices. The GMMs can include a sheet of monolayer (ML) or few-layer (FL) graphene in contact with a magnetic material, such as a ferromagnetic (FM) or an antiferromagnetic material. Electrode terminals can be disposed on the GMMs to be in electrical contact with the graphene. A magnetic field effect is induced in the graphene sheet based on an exchange magnetic field resulting from a magnetization of the magnetic material which is in contact with graphene. Electrical characteristics of the graphene can be manipulated based on the magnetization of the magnetic material in the GMM.

In situ electric properties of Ag films deposited on rough substrates

NASA Astrophysics Data System (ADS)

Zhou, Hong; Yu, Sen-Jiang; Zhang, Yong-Ju; Chen, Miao-Gen; Jiao, Zhi-Wei; Si, Ping-Zhan

2013-01-01

Silver (Ag) films have been deposited on rough substrates (including frosted glass and silicone grease), and for comparison on flat glass, by DC-magnetron sputtering, and their sheet resistances measured in situ during deposition. It is found that the growth of Ag films proceeds through three distinct stages: discontinuous, semi-continuous, and continuous regimes. The sheet resistance on rough substrates jumps in the vicinity of the percolation threshold, whereas the resistance on flat substrates decreases monotonically during deposition. The abnormal in situ electric properties on rough substrates are well explained based on the differences of the growth mechanism and microstructure of Ag films on different substrates.

Magnetic loss and B(H) behaviour of non-oriented electrical sheets under a trapezoidal exciting field

NASA Astrophysics Data System (ADS)

Kedous-Lebouc, A.; Errard, S.; Cornut, B.; Brissonneau, P.

1994-05-01

The excess loss and hysteresis response of electrical steel are measured and discussed in the case of trapezoidal field excitation similar to the current provided by a current commutation supply of a self-synchronous rotating machine. Three industrial non-oriented SiFe samples of different magnetic grades and thicknesses are tested using an automatic Epstein frame equipment. The losses and the unusual observed B( H) loops are analysed in terms of the rate of change of the field, the diffusion of the induction inside the sheet and by the calculation of the theoretical hysteresis cycles due to the eddy currents.

Emerging materials for transparent conductive electrodes and their applications in photovoltaics

NASA Astrophysics Data System (ADS)

Zhu, Zhaozhao

Clean and affordable energy, especially solar energy, is becoming more and more important as our annual total energy consumption keeps rising. However, to make solar energy more affordable and accessible, the cost for fabrication, transportation and assembly of all components need to be reduced. As a crucial component for solar cells, transparent conductive electrode (TCE) can determine the cost and performance. A light weight, easy-to-fabricate and cost-effective new generation TCE is thus needed. While indium-doped tin oxide (ITO) has been the most widely used material for commercial applications as TCEs, its cost has gone up due to the limited global supply of indium. This is not only due to the scarcity of the element itself, but also the massive production of various opto-electronic devices such as TVs, smartphones and tablets. In order to reduce the cost for fabricating large area solar cells, substitute materials for ITO should be developed. These materials should have similar optical transmittance in the visible wavelength range, as well as similar electrical conductivity (sheet resistance) to ITO. This work starts with synthesizing ITO-replacing nano-materials, such as copper nanowires (CuNWs), derivative zinc oxide (ZnO) thin films, reduced graphene oxide (rGO) and so on. Further, we applied various deposition techniques, including spin-coating, spray-coating, Mayer-rod coating, filtration and transferring, to coat transparent substrates with these materials in order to fabricate TCEs. We characterize these materials and analyze their electrical/optical properties as TCEs. Additionally, these fabricated single-material-based TCEs were tested in various lab conditions, and their shortcomings (instability, rigidity, etc.) were highlighted. In order to address these issues, we hybridized the different materials to combine their strengths and compared the properties to single-material based TCEs. The multiple hybridized TCEs have comparable optical/electrical metrics to ITO. The doped-ZnO TCEs exhibit high optical transmittance over 90% in the visible range and low sheet resistance under 200 O/sq. For CuNW-based composite electrodes, ˜ 85% optical transmittance and ˜ 25 O/sq were observed. Meanwhile, the hybridization of materials adds additional features such as flexibility or resistance to corrosion. Finally, as a proof of concept, the CuNW-based composite TCEs were tested in dye-sensitized solar cells (DSSCs), showing similar performance to ITO based samples.