7 CFR 1717.852 - Financing purposes.

Code of Federal Regulations, 2012 CFR

2012-01-01

... AGRICULTURE POST-LOAN POLICIES AND PROCEDURES COMMON TO INSURED AND GUARANTEED ELECTRIC LOANS Lien... facilities, including real property, used to supply electric and/or steam power to: (i) RE Act beneficiaries... are determined by RUS to be an integral component of the borrower's system of supplying electric and...

High temperature superconducting fault current limiter

DOEpatents

Hull, J.R.

1997-02-04

A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

ESTEC wiring test programme materials related properties

NASA Technical Reports Server (NTRS)

Judd, M. D.

1994-01-01

Electrical wires are considered as EEE parts and are covered within the ESA SCC specification series (ESA SCC 3901/XXX). This specification defines the principal properties of the wires including insulation/lay-up and electrical properties. Some additional space related materials requirements are also included, requirements such as outgassing and silver plating thickness. If a project has additional materials requirements over and above those covered by the relevant SCC specification, then additional testing is required. This is especially true for crewed spacecraft. The following topics are discussed in this context: additional requirements for manned spacecraft; flammability; arc tracking; thermal decomposition; microbial surface growth; and ageing.

Nuclear relaxation and vibrational contributions to the static electrical properties of polyatomic molecules: beyond the Hartree-Fock approximation

NASA Astrophysics Data System (ADS)

Luis, Josep M.; Martí, Josep; Duran, Miquel; Andrés, JoséL.

1997-04-01

Electronic and nuclear contributions to the static molecular electrical properties, along with the Stark tuning rate ( δνE ) and the infrared cross section changes ( δSE) have been calculated at the SCF level and at different correlated levels of theory, using a TZ2P basis set and finite field techniques. Nuclear contributions to these molecular properties have also been calculated using a recent analytical approach that allow both to check the accuracy of the finite field values, and to evaluate the importance of higher-order derivatives. The HF, CO, H 2O, H 2CO, and CH 4 molecules have been studied and the results compared to experimental date when available. The paper shows that nuclear relaxation and vibrational contributions must be included in order to obtain accurate values of the static electrical properties. Two different, combined approaches are proposed to predict experimental values of the electrical properties to an error smaller than 5%.

Diffusion in liquid metal systems. [information on electrical resistivity and thermal conductivity

NASA Technical Reports Server (NTRS)

Ukanwa, A. O.

1975-01-01

Physical properties of twenty liquid metals are reported; some of the data on such liquid metal properties as density, electrical resistivity, thermal conductivity, and heat capacity are summarized in graphical form. Data on laboratory handling and safety procedure are summarized for each metal; heat-transfer-correlations for liquid metals under various conditions of laminar and turbulent flow are included. Where sufficient data were available, temperature equations of properties were obtained by the method of least-squares fit. All values of properties given are valid in the given liquid phase ranges only. Additional tabular data on some 40 metals are reported in the appendix. Included is a brief description of experiments that were performed to investigate diffusion in liquid indium-gallium systems.

High temperature superconducting fault current limiter

DOEpatents

Hull, John R.

1997-01-01

A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

7 CFR 1717.852 - Financing purposes.

Code of Federal Regulations, 2010 CFR

2010-01-01

... facilities, including real property, used to supply electric and/or steam power to: (i) RE Act beneficiaries... are determined by RUS to be an integral component of the borrower's system of supplying electric and... electric and/or steam power to end-user customers of the borrower; (3) Investments in a lender required of...

A General Design Rule to Manipulate Photocarrier Transport Path in Solar Cells and Its Realization by the Plasmonic-Electrical Effect

NASA Astrophysics Data System (ADS)

Sha, Wei E. I.; Zhu, Hugh L.; Chen, Luzhou; Chew, Weng Cho; Choy, Wallace C. H.

2015-02-01

It is well known that transport paths of photocarriers (electrons and holes) before collected by electrodes strongly affect bulk recombination and thus electrical properties of solar cells, including open-circuit voltage and fill factor. For boosting device performance, a general design rule, tailored to arbitrary electron to hole mobility ratio, is proposed to decide the transport paths of photocarriers. Due to a unique ability to localize and concentrate light, plasmonics is explored to manipulate photocarrier transport through spatially redistributing light absorption at the active layer of devices. Without changing the active materials, we conceive a plasmonic-electrical concept, which tunes electrical properties of solar cells via the plasmon-modified optical field distribution, to realize the design rule. Incorporating spectrally and spatially configurable metallic nanostructures, thin-film solar cells are theoretically modelled and experimentally fabricated to validate the design rule and verify the plasmonic-tunable electrical properties. The general design rule, together with the plasmonic-electrical effect, contributes to the evolution of emerging photovoltaics.

Realization of MEMS-IC Vertical Integration Utilizing Smart Bumpless Bonding

NASA Astrophysics Data System (ADS)

Shiozaki, Masayoshi; Moriguchi, Makoto; Sasaki, Sho; Oba, Masatoshi

This paper reports fundamental technologies, properties, and new experimental results of SBB (Smart Bumpless Bonding) to realize MEMS-IC vertical integration. Although conventional bonding technologies have had difficulties integrating MEMS and its processing circuit because of their rough bonding surfaces, fragile structures, and thermal restriction, SBB technology realized the vertical integration without thermal treatment, any adhesive materials including bumps, and chemical mechanical polishing. The SBB technology bonds sealing parts for vacuum sealing and electrodes for electrical connection simultaneously as published in previous experimental study. The plasma CVD SiO2 is utilized to realize vacuum sealing as sealing material. And Au projection studs are formed on each electrode and connected electrically between two wafers by compressive plastic deformation and surface activation. In this paper, new experimental results including vacuum sealing properties, electrical improvement, IC bonding results on the described fundamental concept and properties are reported.

The effect of different surfactants/plastisizers on the electrical behavior of CNT nano-modified cement mortars

NASA Astrophysics Data System (ADS)

Dalla, P. T.; Alafogianni, P.; Tragazikis, I. K.; Exarchos, D. A.; Dassios, K.; Barkoula, N.-M.; Matikas, T. E.

2015-03-01

Cement-based materials have in general low electrical conductivity. Electrical conductivity is the measure of the ability of the material to resist the passage of electrical current. The addition of a conductive admixture such as Multi-Walled Carbon Nanotubes (MWCNTs) in a cement-based material increases the conductivity of the structure. This research aims to characterize nano-modified cement mortars with MWCNT reinforcements. Such nano-composites would possess smartness and multi-functionality. Multifunctional properties include electrical, thermal and piezo-electric characteristics. One of these properties, the electrical conductivity, was measured using a custom made apparatus that allows application of known D.C. voltage on the nano-composite. In this study, the influence of different surfactants/plasticizers on CNT nano-modified cement mortar specimens with various concentrations of CNTs (0.2% wt. cement CNTs - 0.8% wt. cement CNTs) on the electrical conductivity is assessed.

Electrical properties study under radiation of the 3D-open-shell-electrode detector

NASA Astrophysics Data System (ADS)

Liu, Manwen; Li, Zheng

2018-05-01

Since the 3D-Open-Shell-Electrode Detector (3DOSED) is proposed and the structure is optimized, it is important to study 3DOSED's electrical properties to determine the detector's working performance, especially in the heavy radiation environments, like the Large Hadron Collider (LHC) and it's upgrade, the High Luminosity (HL-LHC) at CERN. In this work, full 3D technology computer-aided design (TCAD) simulations have been done on this novel silicon detector structure. Simulated detector properties include the electric field distribution, the electric potential distribution, current-voltage (I-V) characteristics, capacitance-voltage (C-V) characteristics, charge collection property, and full depletion voltage. Through the analysis of calculations and simulation results, we find that the 3DOSED's electric field and potential distributions are very uniform, even in the tiny region near the shell openings with little perturbations. The novel detector fits the designing purpose of collecting charges generated by particle/light in a good fashion with a well defined funnel shape of electric potential distribution that makes these charges drifting towards the center collection electrode. Furthermore, by analyzing the I-V, C-V, charge collection property and full depletion voltage, we can expect that the novel detector will perform well, even in the heavy radiation environments.

Dual percolation behaviors of electrical and thermal conductivity in metal-ceramic composites

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

Sun, K.; Zhang, Z. D.; Qian, L.

2016-02-08

The thermal and electrical properties including the permittivity spectra in radio frequency region were investigated for copper/yttrium iron garnet (Cu/YIG) composites. Interestingly, the percolation behaviors in electrical and thermal conductivity were obtained due to the formation of copper particles' networks. Beyond the electrical percolation threshold, negative permittivity was observed and plasmon frequency was reduced by several orders of magnitude. With the increase in copper content, the thermal conductivity was gradually increased; meanwhile, the phonon scattering effect and thermal resistance get enhanced, so the rate of increase in thermal conductivity gradually slows down. Hopefully, Cu/YIG composites with tunable electrical and thermalmore » properties have great potentials for electromagnetic interference shielding and electromagnetic wave attenuation.« less

Inspecting Friction Stir Welding using Electromagnetic Probes

NASA Technical Reports Server (NTRS)

Kinchen, David G.

2004-01-01

A report describes the use of advanced electromagnetic probes to measure the dimensions, the spatial distribution of electrical conductivity, and related other properties of friction stir welds (FSWs) between parts made of the same or different aluminum alloy(s). The probes are of the type described in in another Tech Brief. To recapitulate: A probe of this type is essentially an eddy-current probe that includes a primary (driver) winding that meanders and multiple secondary (sensing) windings that meander along the primary winding. Electrical conductivity is commonly used as a measure of heat treatment and tempering of aluminum alloys, but prior to the development of these probes, the inadequate sensitivity and limited accuracy of electrical-conductivity probes precluded such use on FSWs between different aluminum alloys, and the resolution of those probes was inadequate for measurement of FSW dimensions with positions and metallurgical properties. In contrast, the present probes afford adequate accuracy and spatial resolution for the purposes of measuring the dimensions of FSW welds and correlating spatially varying electrical conductivities with metallurgical properties, including surface defects.

Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

PubMed Central

Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

2015-01-01

This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications. PMID:25938973

Mechanical and Electrical Properties of a Polyimide Film Significantly Enhanced by the Addition of Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Meador, Michael A.

2005-01-01

Single-wall carbon nanotubes have been shown to possess a combination of outstanding mechanical, electrical, and thermal properties. The use of carbon nanotubes as an additive to improve the mechanical properties of polymers and/or enhance their thermal and electrical conductivity has been a topic of intense interest. Nanotube-modified polymeric materials could find a variety of applications in NASA missions including large-area antennas, solar arrays, and solar sails; radiation shielding materials for vehicles, habitats, and extravehicular activity suits; and multifunctional materials for vehicle structures and habitats. Use of these revolutionary materials could reduce vehicle weight significantly and improve vehicle performance and capabilities.

Effects of silver impurity on the structural, electrical, and optical properties of ZnO nanowires

PubMed Central

2011-01-01

1, 3, and 5 wt.% silver-doped ZnO (SZO) nanowires (NWs) are grown by hot-walled pulsed laser deposition. After silver-doping process, SZO NWs show some change behaviors, including structural, electrical, and optical properties. In case of structural property, the primary growth plane of SZO NWs is switched from (002) to (103) plane, and the electrical properties of SZO NWs are variously measured to be about 4.26 × 106, 1.34 × 106, and 3.04 × 105 Ω for 1, 3, and 5 SZO NWs, respectively. In other words, the electrical properties of SZO NWs depend on different Ag ratios resulting in controlling the carrier concentration. Finally, the optical properties of SZO NWs are investigated to confirm p-type semiconductor by observing the exciton bound to a neutral acceptor (A0X). Also, Ag presence in ZnO NWs is directly detected by both X-ray photoelectron spectroscopy and energy dispersive spectroscopy. These results imply that Ag doping facilitates the possibility of changing the properties in ZnO NWs by the atomic substitution of Ag with Zn in the lattice. PMID:21985620

Electrical and mechanical properties of Sn-5wt.%Sb alloy with annealing temperature

NASA Astrophysics Data System (ADS)

Said Gouda, El; Ahmed, E. M.; Saad Allah, F. A.

2009-01-01

A binary Sn-5wt.%Sb solder alloy was chosen as a potential alternative to Sn-Pb solder alloy to be subjected to many studies. It was casted from the liquid state, cold drawn into wires of 1 mm diameters. The study includes the structure, electrical resistivity, tensile strength, hardness and indentation creep behavior using XRD, four probes electrical circuit, conventional tensile testing machine, Vickers microhardness tester, respectively. These properties were carried out for the cold worked alloy and after annealing at 393 and 473 K for 60 min. It was found that annealed samples exhibit more precipitations of the intermetallic compounds SnSb, higher lattice parameters and higher crystallite size, while have lower lattice-strain induced due to the cold working process. These structural changes greatly affect the electrical resistivity and mechanical properties of this alloy.

Low Temperature Noise and Electrical Characterization of the Company Heterojunction Field-Effect Transistor

NASA Technical Reports Server (NTRS)

Cunningham, Thomas J.; Gee, Russell C.; Fossum, Eric R.; Baier, Steven M.

1993-01-01

This paper discusses the electrical properties of the complementary heterojunction field-effect transistor (CHFET) at 4K, including the gate leakage current, the subthreshold transconductance, and the input-referred noise voltage.

Static electricity: A literature review

NASA Astrophysics Data System (ADS)

Crow, Rita M.

1991-11-01

The major concern with static electricity is its discharging in a flammable atmosphere which can explode and cause a fire. Textile materials can have their electrical resistivity decreased by the addition of antistatic finishes, imbedding conductive particles into the fibres or by adding metal fibers to the yarns. The test methods used in the studies of static electricity include measuring the static properties of materials, of clothed persons, and of the ignition energy of flammable gases. Surveys have shown that there is sparse evidence for fires definitively being caused by static electricity. However, the 'worst-case' philosophy has been adopted and a static electricity safety code is described, including correct grounding procedures and the wearing of anti-static clothing and footwear.

Electrical and Self-Sensing Properties of Ultra-High-Performance Fiber-Reinforced Concrete with Carbon Nanotubes

PubMed Central

You, Ilhwan; Yoo, Doo-Yeol; Kim, Soonho; Kim, Min-Jae; Zi, Goangseup

2017-01-01

This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state. PMID:29109388

Electrical and Self-Sensing Properties of Ultra-High-Performance Fiber-Reinforced Concrete with Carbon Nanotubes.

PubMed

You, Ilhwan; Yoo, Doo-Yeol; Kim, Sooho; Kim, Min-Jae; Zi, Goangseup

2017-10-29

This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state.

Congeneration feasibility: Otis Elavator Company and Polychrome Corporation

NASA Astrophysics Data System (ADS)

Fox, H.

1982-05-01

An investigation of the technical and economic feasibility of cogenerating electric and thermal power at two manufacturing plants (Otis Elevator Company and Polychrome Corporation) located on neighboring properties in Yonkers, NY is discussed. Existing electrical and steam producing equipment and energy consumption date are summarized. Alternative cases examined include electrical energy generation, electrical energy generation with waste heat recovery and a combined cycle case. Also reported are life cycle cost economic evaluations including simple payback period and return on investment indices. While it was concluded that cogeneration of heat and electricity at these industrial plant sites would not be economically viable, this detailed study provides valuable insights.

Pulsed electric fields for pasteurization: defining processing conditions

USDA-ARS?s Scientific Manuscript database

Application of pulsed electric fields (PEF) technology in food pasteurization has been extensively studied. Optimal PEF treatment conditions for maximum microbial inactivation depend on multiple factors including PEF processing conditions, production parameters and product properties. In order for...

Hazardous Waste Cleanup: General Electric - Auburn Plant in Auburn, New York

EPA Pesticide Factsheets

GE purchased the property at Genesee Street in 1951 and constructed a manufacturing plant that produced a variety of electrical components including radar equipment, printed circuit boards and high voltage semiconductors. In January 1986, Powerex, Inc.,

Investigation of electrical and impact properties of carbon fiber reinforced polymer matrix composites with carbon nanotube buckypaper layers

NASA Astrophysics Data System (ADS)

Hill, Christopher Brandon

Carbon fiber reinforced composite materials have become commonplace in many industries including aerospace, automotive, and sporting goods. Previous research has determined a coupling relationship between the mechanical and electrical properties of these materials where the application of electrical current has been shown to improve their mechanical strengths. The next generations of these composites have started to be produced with the addition of nanocarbon buckypaper layers which provide even greater strength and electrical conductivity potentials. The focus of this current research was to characterize these new composites and compare their electro-mechanical coupling capabilities to those composites which do not contain any nonocarbons.

Cellulose-Based Smart Fluids under Applied Electric Fields

PubMed Central

Choi, Kisuk; Gao, Chun Yan; Nam, Jae Do

2017-01-01

Cellulose particles, their derivatives and composites have special environmentally benign features and are abundant in nature with their various applications. This review paper introduces the essential properties of several types of cellulose and their derivatives obtained from various source materials, and their use in electro-responsive electrorheological (ER) suspensions, which are smart fluid systems that are actively responsive under applied electric fields, while, at zero electric field, ER fluids retain a liquid-like state. Given the actively controllable characteristics of cellulose-based smart ER fluids under an applied electric field regarding their rheological and dielectric properties, they can potentially be applied for various industrial devices including dampers and haptic devices. PMID:28891966

41 CFR 101-26.509-1 - Requisitioning tabulating machine cards available from Federal Supply Schedule contracts.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 41 Public Contracts and Property Management 2 2011-07-01 2007-07-01 true Requisitioning tabulating... Contracts and Property Management Federal Property Management Regulations System FEDERAL PROPERTY MANAGEMENT... electrical and mechanical contact tabulating machines, including aperture cards and copy cards. Federal...

41 CFR 101-26.509-1 - Requisitioning tabulating machine cards available from Federal Supply Schedule contracts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Requisitioning tabulating... Contracts and Property Management Federal Property Management Regulations System FEDERAL PROPERTY MANAGEMENT... electrical and mechanical contact tabulating machines, including aperture cards and copy cards. Federal...

Tetrazole amphiphile inducing growth of conducting polymers hierarchical nanostructures and their electromagnetic absorption properties

NASA Astrophysics Data System (ADS)

Xie, Aming; Sun, Mengxiao; Zhang, Kun; Xia, Yilu; Wu, Fan

2018-05-01

Conducting polymers (CPs) at nano scales endow materials with special optical, electrical, and magnetic properties. The crucial factor to construct and regulate the micro-structures of CPs is the inducing reagent, particular in its chemical structure, such active sites, self-assembling properties. In this paper, we design and synthesize an amphiphile bearing tetrazole moiety on its skeleton, and use this amphiphile as an inducing reagent to prepare and regulate the micro-structures of a series of CPs including polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and poly(p-phenylenediamine). Because of the unique electric properties of CPs and size effect, we next explored the electromagnetic absorption performances of these CPs nanostructures. A synergetic combination of electric loss and magnetic loss is used to explain the absorption mechanism of these CPs nano-structures.

UCP2- and non-UCP2-mediated electric current in eukaryotic cells exhibits different properties.

PubMed

Wang, Ruihua; MoYung, K C; Zhang, M H; Poon, Karen

2015-12-01

Using live eukaryotic cells, including cancer cells, MCF-7 and HCT-116, normal hepatocytes and red blood cells in anode and potassium ferricyanide in cathode of MFC could generate bio-based electric current. Electrons and protons generated from the metabolic reaction in both cytosol and mitochondria contributing to the leaking would mediate the generation of electric current. Both resveratrol (RVT) and 2,4-dinitrophenol (DNP) used to induce proton leak in mitochondria were found to promote electric current production in all cells except red blood cells without mitochondria. Proton leak might be important for electric current production by bringing the charge balance in cells to enhance the further electron leak. The induced electric current by RVT can be blocked by Genipin, an inhibitor of UCP2-mediated proton leak, while that induced by DNP cannot. RVT could reduce reactive oxygen species (ROS) level in cells better than that of DNP. In addition, RVT increased mitochondrial membrane potential (MMP), while DNP decreased it. Results highly suggested the existence of at least two types of electric current that showed different properties. They included UCP2-mediated and non-UCP2-mediated electric current. UCP2-mediated electric current exhibited higher reactive oxygen species (ROS) reduction effect per unit electric current production than that of non-UCP2-mediated electric current. Higher UCP2-mediated electric current observed in cancer cells might contribute to the mechanism of drug resistence. Correlation could not be established between electric current production with either ROS and MMP without distinguishing the types of electric current.

Hazardous Waste Cleanup: General Electric – Main Plant Site in Schenectady, New York

EPA Pesticide Factsheets

GE purchased the property at Genesee Street in 1951 and constructed a manufacturing plant that produced a variety of electrical components including radar equipment, printed circuit boards and high voltage semiconductors. In January 1986, Powerex, Inc., ac

Theoretical study of the influence of the electric field on the electronic properties of armchair boron nitride nanoribbon

NASA Astrophysics Data System (ADS)

Chegel, Raad; Behzad, Somayeh

2014-11-01

We have investigated the electronic properties of A-BNNRs in the external electric field using third nearest neighbor tight binding approximation including edge effects. We found that the dependence of on-site energy to the external electric field for edge atoms and center part atoms is different. By comparing the band structure in the different fields, several differences are clearly seen such as modification of energy dispersions, creation of additional band edge states and band gap reduction. By increasing the electric field the band gap reduces linearly until reaches zero and BNNRs with larger width are more sensitive than small ones. All changes in the band structure are directly reflected in the DOS spectrum. The numbers and the energies of the DOS peaks are dependent on the electric field strength.

75 FR 22589 - Cordova Electric Cooperative, Inc.; Notice of Proposed Restricted Service List for a Programmatic...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-29

... a Programmatic Agreement for Managing Properties Included in or Eligible for Inclusion in the... a programmatic agreement for managing properties included in, or eligible for inclusion in, the... person on the official service list for the above-captioned proceeding may request inclusion on the...

75 FR 30021 - South Carolina Electric & Gas Company Saluda Hydroelectric Project; Notice of Proposed Restricted...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-28

... Service List for a Programmatic Agreement for Managing Properties Included In or Eligible for Inclusion In... agreement for managing properties included in, or eligible for inclusion in, the National Register of... request inclusion on the restricted service list, or may request that a restricted service list not be...

Molecular dynamics study of response of liquid N,N-dimethylformamide to externally applied electric field using a polarizable force field

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

Gao, Weimin; Niu, Haitao; Lin, Tong

2014-01-28

The behavior of Liquid N,N-dimethylformamide subjected to a wide range of externally applied electric fields (from 0.001 V/nm to 1 V/nm) has been investigated through molecular dynamics simulation. To approach the objective the AMOEBA polarizable force field was extended to include the interaction of the external electric field with atomic partial charges and the contribution to the atomic polarization. The simulation results were evaluated with quantum mechanical calculations. The results from the present force field for the liquid at normal conditions were compared with the experimental and molecular dynamics results with non-polarizable and other polarizable force fields. The uniform externalmore » electric fields of higher than 0.01 V/nm have a significant effect on the structure of the liquid, which exhibits a variation in numerous properties, including molecular polarization, local cluster structure, rotation, alignment, energetics, and bulk thermodynamic and structural properties.« less

Effect of contact barrier on electron transport in graphene.

PubMed

Zhou, Yang-Bo; Han, Bing-Hong; Liao, Zhi-Min; Zhao, Qing; Xu, Jun; Yu, Da-Peng

2010-01-14

The influence of the barrier between metal electrodes and graphene on the electrical properties was studied on a two-electrode device. A classical barrier model was used to analyze the current-voltage characteristics. Primary parameters including barrier height and effective resistance were achieved. The electron transport properties under magnetic field were further investigated. An abnormal peak-valley-peak shape of voltage-magnetoresistance curve was observed. The underlying mechanisms were discussed under the consideration of the important influence of the contact barrier. Our results indicate electrical properties of graphene based devices are sensitive to the contact interface.

Electrical and Magnetic Measurements from microHertz to teraHertz (Invited)

NASA Astrophysics Data System (ADS)

Olhoeft, G. R.

2009-12-01

In making electrical and magnetic measurements, half the problem is the measurement of the properties of the rocks, soils and fluids, and half the problem is duplicating the environment. Equally important with applying a field stimulus and measuring the response are fluid content and chemistry, temperature, pressure, time and other factors. The magnetic properties of Martian soils are not interesting under terrestrial ambient lab temperatures (298 K), but exhibit a very interesting relaxation at Mars ambient temperatures (213 K) which is important in radar sounding. The electrical properties of granite are nearly identical at 523 K vacuum dry and 263 K water saturated which is important in geothermal exploration. The most common zeolite, clinoptilolite, can behave like kaolinite or montmorillonite depending upon salinity and temperature in many of its properties. Making measurements at very high frequencies can make frozen water look like a clear ice cube or a white opaque snowball depending upon grain size scattering and thermal history. Low frequency measurements are more sensitive to chemistry as reactions can't keep up at high frequencies. In situ measurements are more complicated (including effects of heterogeneity and scale), but laboratory measurements allow investigation of more variables to understand process and property controlling factors, including effects of removing the sample from its environment.

A biopolymer transistor: electrical amplification by microtubules.

PubMed

Priel, Avner; Ramos, Arnolt J; Tuszynski, Jack A; Cantiello, Horacio F

2006-06-15

Microtubules (MTs) are important cytoskeletal structures engaged in a number of specific cellular activities, including vesicular traffic, cell cyto-architecture and motility, cell division, and information processing within neuronal processes. MTs have also been implicated in higher neuronal functions, including memory and the emergence of "consciousness". How MTs handle and process electrical information, however, is heretofore unknown. Here we show new electrodynamic properties of MTs. Isolated, taxol-stabilized MTs behave as biomolecular transistors capable of amplifying electrical information. Electrical amplification by MTs can lead to the enhancement of dynamic information, and processivity in neurons can be conceptualized as an "ionic-based" transistor, which may affect, among other known functions, neuronal computational capabilities.

Proceedings of the 13th biennial conference on carbon. Extended abstracts and program

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

None

1977-01-01

Properties of carbon are covered including: mechanical and frictional properties; chemical reactivity and surfaces; aerospace applications; carbonization and graphitization; industrial applications; electrical and thermal properties; biomaterials applications; fibers and composites; nuclear applications; activated carbon and adsorption; advances in carbon characterization; and micromechanics and modeling. (GHT)

Electro-mechanical characterization of structural supercapacitors

NASA Astrophysics Data System (ADS)

Gallagher, T.; LaMaster, D.; Ciocanel, C.; Browder, C.

2012-04-01

The paper presents electrical and mechanical properties of structural supercapacitors and discusses limitations associated with the approach taken for the electrical properties evaluation. The structural supercapacitors characterized in this work had the electrodes made of carbon fiber weave, separator made of several cellulose based products, and the solid electrolyte made as PEGDGE based polymer blend. The reported electrical properties include capacitance and leakage resistance; the former was measured using cyclic voltammetry. Mechanical properties have been evaluated thorough tensile and three point bending tests performed on structural supercapacitor coupons. The results indicate that the separator material plays an important role on the electrical as well as mechanical properties of the structural capacitor, and that Celgard 3501 used as separator leads to most benefits for both mechanical and electrical properties. Specific capacitance and leakage resistance as high as 1.4kF/m3 and 380kΩ, respectively, were achieved. Two types of solid polymer electrolytes were used in fabrication, with one leading to higher and more consistent leakage resistance values at the expense of a slight decrease in specific capacitance when compared to the other SPE formulation. The ultimate tensile strength and modulus of elasticity of the developed power storage composite were evaluated at 466MPa and 18.9MPa, respectively. These values are 58% and 69% of the tensile strength and modulus of elasticity values measured for a single layer composite material made with the same type of carbon fiber and with a West System 105 epoxy instead of solid polymer electrolyte.

Congeneration feasibility: Otis Elevator Company and Polychrome Corporation. Final report

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

Fox, H.

1982-05-01

This report summarizes an investigation of the technical and economic feasibility of cogenerating electric and thermal power at two manufacturing plants (Otis Elevator Company and Polychrome Corporation) located on neighboring properties in Yonkers, NY. Existing electrical- and steam-producing equipment and energy consumption date are summarized. Alternative cases examined include electrical energy generation, electrical energy generation with waste heat recovery and a combined cycle case. Also reported are life cycle cost economic evaluations including simple payback period and return-on-investment indices. While it was concluded that cogeneration of heat and electricity at these industrial plant sites would not be economically viable, thismore » detailed study provides valuable insight into the types of problems encountered when considering cogeneration feasibility.« less

Environmental Aging of Polymer-Nano Composites and Release of Carbon Nanotube

EPA Science Inventory

Epoxies are widely used in various applications, including coatings, electronics insulations, and waterproofing applications due to their excellent properties such as good adhesion, electrical insulation, and heat resistance along with the strong mechanical property. Currently, n...

Photodetectors using III-V nitrides

DOEpatents

Moustakas, T.D.; Misra, M.

1997-10-14

A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector. 24 figs.

Photodetectors using III-V nitrides

DOEpatents

Moustakas, Theodore D.; Misra, Mira

1997-01-01

A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector.

Property and microstructural nonuniformity in the yttrium-barium-copper-oxide superconductor determined from electrical, magnetic, and ultrasonic measurements. Ph.D. Thesis - Case Western Reserve Univ.

NASA Technical Reports Server (NTRS)

Roth, Don J.

1991-01-01

The purpose of this dissertation was the following: (1) to characterize the effect of pore fraction on a comprehensive set of electrical and magnetic properties for the yttrium-barium-copper-oxide (YBCO) high temperature ceramic superconductor; and (2) to determine the viability of using a room-temperature, nondestructive characterization method to aid in the prediction of superconducting (cryogenic) properties. The latter involved correlating ultrasonic velocity measurements at room temperature with property-affecting pore fraction and oxygen content variations. The use of ultrasonic velocity for estimating pore fraction in YBCO is presented, and other polycrystalline materials are reviewed, modeled, and statistically analyzed. This provides the basis for using ultrasonic velocity to interrogate microstructure. The effect of pore fraction (0.10-0.25) on superconductor properties of YBCO samples was characterized. Spatial (within-sample) variations in microstructure and superconductor properties were investigated, and the effect of oxygen content on elastic behavior was examined. Experimental methods used included a.c. susceptibility, electrical, and ultrasonic velocity measurements. Superconductor properties measured included transition temperature, magnetic transition width, transport and magnetic critical current density, magnetic shielding, a.c. loss, and sharpness of the voltage-current characteristics. An ultrasonic velocity image constructed from measurements at 1mm increments across a YBCO sample revealed microstructural variations that correlated with variations in magnetic shielding and a.c. loss behavior. Destructive examination using quantitative image analysis revealed pore fraction to be the varying microstructural feature.

Bio-heat transfer model of electroconvulsive therapy: Effect of biological properties on induced temperature variation.

PubMed

de Oliveira, Marilia M; Wen, Paul; Ahfock, Tony

2016-08-01

A realistic human head model consisting of six tissue layers was modelled to investigate the behavior of temperature profile and magnitude when applying electroconvulsive therapy stimulation and different biological properties. The thermo-electrical model was constructed with the use of bio-heat transfer equation and Laplace equation. Three different electrode montages were analyzed as well as the influence of blood perfusion, metabolic heat and electric and thermal conductivity in the scalp. Also, the effect of including the fat layer was investigated. The results showed that temperature increase is inversely proportional to electrical and thermal conductivity increase. Furthermore, the inclusion of blood perfusion slightly drops the peak temperature. Finally, the inclusion of fat is highly recommended in order to acquire more realistic results from the thermo-electrical models.

Science Notes.

ERIC Educational Resources Information Center

School Science Review, 1990

1990-01-01

Included are 30 science activities that include computer monitoring, fieldwork, enzyme activity, pH, drugs, calorimeters, Raoult's Law, food content, solubility, electrochemistry, titration, physical properties of materials, gel filtration, energy, concepts in physics, and electricity. (KR)

The Effect of Particles on Electrolytically Polymerized Thin Natural MCF Rubber for Soft Sensors Installed in Artificial Skin.

PubMed

Shimada, Kunio; Mochizuki, Osamu; Kubota, Yoshihiro

2017-04-19

The aim of this study is to investigate the effect of particles as filler in soft rubber sensors installed in artificial skin. We examine sensors made of natural rubber (NR-latex) that include magnetic particles of Ni and Fe₃O₄ using magnetic compound fluid (MCF). The 1-mm thickness of the electrolytically polymerized MCF rubber makes production of comparatively thin rubber sensors feasible. We first investigate the effect of magnetic particles Ni and Fe₃O₄ on the curing of MCF rubber. Next, in order to adjust the electric properties of the MCF rubber, we adopt Al₂O₃ dielectric particles. We investigate the effect of Al₂O₃ particles on changes in electric current, voltage and temperature of electrolytically polymerized MCF rubber liquid, and on the electric properties under the application of normal and shear forces. By adjusting the ratio of Ni, Fe₃O₄, Al₂O₃ and water in MCF rubber with Al₂O₃, it is possible to change the electric properties.

Non- contacting capacitive diagnostic device

DOEpatents

Ellison, Timothy

2005-07-12

A non-contacting capacitive diagnostic device includes a pulsed light source for producing an electric field in a semiconductor or photovoltaic device or material to be evaluated and a circuit responsive to the electric field. The circuit is not in physical contact with the device or material being evaluated and produces an electrical signal characteristic of the electric field produced in the device or material. The diagnostic device permits quality control and evaluation of semiconductor or photovoltaic device properties in continuous manufacturing processes.

Impact of Magneto-Electric Materials and Devices on Tactical Radio (and Radar)

DTIC Science & Technology

2007-04-01

and frequency dependent variable permittivity in a single device • Magnetic properties controlled by electric field. The goals of the seedling...such as HoMnO3) and composites (such as PZT- Terfenol-D). Other possible candidate materials are thought to include colossal magnetoresistive oxides

GlassForm

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

2011-09-16

GlassForm is a software tool for generating preliminary waste glass formulas for a given waste stream. The software is useful because it reduces the number of verification melts required to develop a suitable additive composition. The software includes property models that calculate glass properties of interest from the chemical composition of the waste glass. The software includes property models for glass viscosity, electrical conductivity, glass transition temperature, and leach resistance as measured by the 7-day product consistency test (PCT).

Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices.

PubMed

Torres, Juan C; Vergaz, Ricardo; Barrios, David; Sánchez-Pena, José Manuel; Viñuales, Ana; Grande, Hans Jürgen; Cabañero, Germán

2014-05-02

A series of polymer dispersed liquid crystal devices using glass substrates have been fabricated and investigated focusing on their electrical properties. The devices have been studied in terms of impedance as a function of frequency. An electric equivalent circuit has been proposed, including the influence of the temperature on the elements into it. In addition, a relevant effect of temperature on electrical measurements has been observed.

Geophysical Signitures From Hydrocarbon Contaminated Aquifers

NASA Astrophysics Data System (ADS)

Abbas, M.; Jardani, A.

2015-12-01

The task of delineating the contamination plumes as well as studying their impact on the soil and groundwater biogeochemical properties is needed to support the remediation efforts and plans. Geophysical methods including electrical resistivity tomography (ERT), induced polarization (IP), ground penetrating radar (GPR), and self-potential (SP) have been previously used to characterize contaminant plumes and investigate their impact on soil and groundwater properties (Atekwana et al., 2002, 2004; Benson et al., 1997; Campbell et al., 1996; Cassidy et al., 2001; Revil et al., 2003; Werkema et al., 2000). Our objective was to: estimate the hydrocarbon contamination extent in a contaminated site in northern France, and to adverse the effects of the oil spill on the groundwater properties. We aim to find a good combination of non-intrusive and low cost methods which we can use to follow the bio-remediation process, which is planned to proceed next year. We used four geophysical methods including electrical resistivity tomography, IP, GPR, and SP. The geophysical data was compared to geochemical ones obtained from 30 boreholes installed in the site during the geophysical surveys. Our results have shown: low electrical resistivity values; high chargeability values; negative SP anomalies; and attenuated GPR reflections coincident with groundwater contamination. Laboratory and field geochemical measurements have demonstrated increased groundwater electrical conductivity and increased microbial activity associated with hydrocarbon contamination of groundwater. Our study results support the conductive model suggested by studies such as Sauck (2000) and Atekwana et al., (2004), who suggest that biological alterations of hydrocarbon contamination can substantially modify the chemical and physical properties of the subsurface, producing a dramatic shift in the geo-electrical signature from resistive to conductive. The next stage of the research will include time lapse borehole and 3D geophysical measurements coupled to biological and chemical surface phase experiments in order to monitor the bioremediation processes.

Do Membranes Dream of Electric Tubes? Advanced Membranes Using Carbon Nanotube - Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

de Lannoy, Charles-Francois Pedro Claude Karolek Ghislain

Membrane technologies represent an energy efficient, effective solution for treating municipal and commercial waters/wastewaters. Membranes are predominantly polymer-based and despite steady advances in polymeric materials, they continue to suffer from operational problems including biofouling and breakages. This work addresses these two disparate problems by developing novel CNT-polymer nanocomposite materials that contain variously functionalized carbon nanotubes (fCNTs) in low quantities (<0.5wt%). Several strategies have been employed to achieve highly functional CNT-polymer nanocomposite membranes including blend mixing, ionic charge association, and covalent cross-linking with monomer and oligomer constituents. These CNT-polymer nanocomposite membranes were compared to traditional polymer membranes across various properties including increased Young's Modulus, changes in surface hydrophilicity, fine control over molecular weight cut-off and flux, and surface electrical conductivity. Membranes with high surface electrical conductivity were further tested for their anti-biofouling properties. Finally, CNT stability and polymer compatibility were evaluated throughout membrane manufacture, use, and cleaning. The incorporation of CNTs mixed in bulk phase and linked through ionic associations in polymer matrices showed significant (50%) increases in Young's modulus for certain CNT functionalizations and derivatization percent. Membranes formed with high surface electrical conductivity demonstrated almost complete resistance to biofouling (> 95%) in long-term bacterially challenged experiments. CNTs and polymer mixtures that lacked covalent or ionic bonds were susceptible to significant (up to 10%) loss of CNTs during membrane non-solvent gelation and aggressive chemical cleaning treatment. Functionalized carbon nanotubes endow polymer membranes with their unique strength and electrically conductive properties. These added properties were demonstrated to greatly improve membrane operational efficiency and membrane longevity. CNT-polymer nanocomposite membranes offer low-energy, high-efficiency, and long-lifetime alternatives to traditional polymer membranes. With further advances in polymeric nanomaterials, membrane technology has the potential for wide applicability across many fields outside of water filtration and desalination.

Applications for Electrical Impedance Tomography (EIT) and Electrical Properties of the Human Body.

PubMed

Lymperopoulos, Georgios; Lymperopoulos, Panagiotis; Alikari, Victoria; Dafogianni, Chrisoula; Zyga, Sofia; Margari, Nikoletta

2017-01-01

Electrical Impedance Tomography (EIT) is a promising application that displays changes in conductivity within a body. The basic principle of the method is the repeated measurement of surface voltages of a body, which are a result of rolling injection of known and small-volume sinusoidal AC current to the body through the electrodes attached to its surface. This method finds application in biomedicine, biology and geology. The objective of this paper is to present the applications of Electrical Impedance Tomography, along with the method's capabilities and limitations due to the electrical properties of the human body. For this purpose, investigation of existing literature has been conducted, using electronic databases, PubMed, Google Scholar and IEEE Xplore. In addition, there was a secondary research phase, using paper citations found during the first research phase. It should be noted that Electrical Impedance Tomography finds use in a plethora of medical applications, as the different tissues of the body have different conductivities and dielectric constants. Main applications of EIT include imaging of lung function, diagnosis of pulmonary embolism, detection of tumors in the chest area and diagnosis and distinction of ischemic and hemorrhagic stroke. EIT advantages include portability, low cost and safety, which the method provide, since it is a noninvasive imaging method that does not cause damage to the body. The main disadvantage of the method, which blocks its wider spread, appears in the image composition from the voltage measurements, which are conducted by electrodes placed on the periphery of the body, because the injected currents are affected nonlinearly by the general distribution of the electrical properties of the body. Furthermore, the complex impedance of the skin-electrode interface can be modelled by using a capacitor and two resistor, as a result of skin properties. In conclusion, Electrical Impedance Tomography is a promising method for the development of noninvasive diagnostic medicine, since it is able to provide imaging of the interior of the human body in real time without causing harm or putting the human body in risk.

Microwave processed NiMg ferrite: Studies on structural and magnetic properties

NASA Astrophysics Data System (ADS)

Chandra Babu Naidu, K.; Madhuri, W.

2016-12-01

Ferrites are magnetic semiconductors realizing an important role in electrical and electronic circuits where electrical and magnetic property coupling is required. Though ferrite materials are known for a long time, there is a large scope in the improvement of their properties (vice sintering and frequency dependence of electrical and magnetic properties) with the current technological trends. Forth coming technology is aimed at miniaturization and smart gadgets, electrical components like inductors and transformers cannot be included in integrated circuits. These components are incorporated into the circuit as surface mount devices whose fabrication involves low temperature co-firing of ceramics and microwave monolithic integrated circuits technologies. These technologies demand low temperature sinter-ability of ferrites. This article presents low temperature microwave sintered Ni-Mg ferrites of general chemical formula Ni1-xMgxFe2O4 (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) for potential applications as transformer core materials. The series of ferrites are characterized using X-ray diffractometer, scanning electron microscopy, Fourier transform infrared and vibrating sample magnetometer for investigating structural, morphological and magnetic properties respectively. The initial permeability is studied with magnesium content, temperature and frequency in the temperature range of 308 K-873 K and 42 Hz-5 MHz.

Understanding individual defects in CdTe thin-film solar cells via STEM: From atomic structure to electrical activity

DOE PAGES

Li, Chen; Poplawsky, Jonathan; Yan, Yanfa; ...

2017-07-01

Here in this paper we review a systematic study of the structure-property correlations of a series of defects in CdTe solar cells. A variety of experimental methods, including aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, energy dispersive X-ray spectroscopy, and electron-beam-induced current have been combined with density-functional theory. The research traces the connections between the structures and electrical activities of individual defects including intra-grain partial dislocations, grain boundaries and the CdTe/CdS interface. The interpretations of the physical origin underlying the structure-property correlation provide insights that should further the development of future CdTe solar cells.

Magnetic and electrical control of engineered materials

DOEpatents

Schuller, Ivan K.; de La Venta Granda, Jose; Wang, Siming; Ramirez, Gabriel; Erekhinskiy, Mikhail; Sharoni, Amos

2016-08-16

Methods, systems, and devices are disclosed for controlling the magnetic and electrical properties of materials. In one aspect, a multi-layer structure includes a first layer comprising a ferromagnetic or ferrimagnetic material, and a second layer positioned within the multi-layer structure such that a first surface of the first layer is in direct physical contact with a second surface of the second layer. The second layer includes a material that undergoes structural phase transitions and metal-insulator transitions upon experiencing a change in temperature. One or both of the first and second layers are structured to allow a structural phase change associated with the second layer cause a change magnetic properties of the first layer.

Understanding individual defects in CdTe thin-film solar cells via STEM: From atomic structure to electrical activity

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

Li, Chen; Poplawsky, Jonathan; Yan, Yanfa

Here in this paper we review a systematic study of the structure-property correlations of a series of defects in CdTe solar cells. A variety of experimental methods, including aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, energy dispersive X-ray spectroscopy, and electron-beam-induced current have been combined with density-functional theory. The research traces the connections between the structures and electrical activities of individual defects including intra-grain partial dislocations, grain boundaries and the CdTe/CdS interface. The interpretations of the physical origin underlying the structure-property correlation provide insights that should further the development of future CdTe solar cells.

Low-dimensional carbon and MXene-based electrochemical capacitor electrodes.

PubMed

Yoon, Yeoheung; Lee, Keunsik; Lee, Hyoyoung

2016-04-29

Due to their unique structure and outstanding intrinsic physical properties such as extraordinarily high electrical conductivity, large surface area, and various chemical functionalities, low-dimension-based materials exhibit great potential for application in electrochemical capacitors (ECs). The electrical properties of electrochemical capacitors are determined by the electrode materials. Because energy charge storage is a surface process, the surface properties of the electrode materials greatly influence the electrochemical performance of the cell. Recently, graphene, a single layer of sp(2)-bonded carbon atoms arrayed into two-dimensional carbon nanomaterial, has attracted wide interest as an electrode material for electrochemical capacitor applications due to its unique properties, including a high electrical conductivity and large surface area. Several low-dimensional materials with large surface areas and high conductivity such as onion-like carbons (OLCs), carbide-derived carbons (CDCs), carbon nanotubes (CNTs), graphene, metal hydroxide, transition metal dichalcogenides (TMDs), and most recently MXene, have been developed for electrochemical capacitors. Therefore, it is useful to understand the current issues of low-dimensional materials and their device applications.

Apparatus for the measurement of electrical resistivity, Seebeck coefficient, and thermal conductivity of thermoelectric materials between 300 K and 12 K

NASA Astrophysics Data System (ADS)

Martin, Joshua; Nolas, George S.

2016-01-01

We have developed a custom apparatus for the consecutive measurement of the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of materials between 300 K and 12 K. These three transport properties provide for a basic understanding of the thermal and electrical properties of materials. They are of fundamental importance in identifying and optimizing new materials for thermoelectric applications. Thermoelectric applications include waste heat recovery for automobile engines and industrial power generators, solid-state refrigeration, and remote power generation for sensors and space probes. The electrical resistivity is measured using a four-probe bipolar technique, the Seebeck coefficient is measured using the quasi-steady-state condition of the differential method in a 2-probe arrangement, and the thermal conductivity is measured using a longitudinal, multiple gradient steady-state technique. We describe the instrumentation and the measurement uncertainty associated with each transport property, each of which is presented with representative measurement comparisons using round robin samples and/or certified reference materials. Transport properties data from this apparatus have supported the identification, development, and phenomenological understanding of novel thermoelectric materials.

Dually actuated triple shape memory polymers of cross-linked polycyclooctene-carbon nanotube/polyethylene nanocomposites.

PubMed

Wang, Zhenwen; Zhao, Jun; Chen, Min; Yang, Minhao; Tang, Luyang; Dang, Zhi-Min; Chen, Fenghua; Huang, Miaoming; Dong, Xia

2014-11-26

In this work, electrically and thermally actuated triple shape memory polymers (SMPs) of chemically cross-linked polycyclooctene (PCO)-multiwalled carbon nanotube (MWCNT)/polyethylene (PE) nanocomposites with co-continuous structure and selective distribution of fillers in PCO phase are prepared. We systematically studied not only the microstructure including morphology and fillers' selective distribution in one phase of the PCO/PE blends, but also the macroscopic properties including thermal, mechanical, and electrical properties. The co-continuous window of the immiscible PCO/PE blends is found to be the volume fraction of PCO (vPCO) of ca. 40-70 vol %. The selective distribution of fillers in one phase of co-continuous blends is obtained by a masterbatch technique. The prepared triple SMP materials show pronounced triple shape memory effects (SMEs) on the dynamic mechanical thermal analysis (DMTA) and the visual observation by both thermal and electric actuations. Such polyolefin samples with well-defined microstructure, electrical actuation, and triple SMEs might have potential applications as, for example, multiple autochoke elements for engines, self-adjusting orthodontic wires, and ophthalmic devices.

Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices

PubMed Central

Torres, Juan C.; Vergaz, Ricardo; Barrios, David; Sánchez-Pena, José Manuel; Viñuales, Ana; Grande, Hans Jürgen; Cabañero, Germán

2014-01-01

A series of polymer dispersed liquid crystal devices using glass substrates have been fabricated and investigated focusing on their electrical properties. The devices have been studied in terms of impedance as a function of frequency. An electric equivalent circuit has been proposed, including the influence of the temperature on the elements into it. In addition, a relevant effect of temperature on electrical measurements has been observed. PMID:28788632

Polyimide/Glass Composite High-Temperature Insulation

NASA Technical Reports Server (NTRS)

Pater, Ruth H.; Vasquez, Peter; Chatlin, Richard L.; Smith, Donald L.; Skalski, Thomas J.; Johnson, Gary S.; Chu, Sang-Hyon

2009-01-01

Lightweight composites of RP46 polyimide and glass fibers have been found to be useful as extraordinarily fire-resistant electrical-insulation materials. RP46 is a polyimide of the polymerization of monomeric reactants (PMR) type, developed by NASA Langley Research Center. RP46 has properties that make it attractive for use in electrical insulation at high temperatures. These properties include high-temperature resistance, low relative permittivity, low dissipation factor, outstanding mechanical properties, and excellent resistance to moisture and chemicals. Moreover, RP46 contains no halogen or other toxic materials and when burned it does not produce toxic fume or gaseous materials. The U. S. Navy has been seeking lightweight, high-temperature-resistant electrical-insulation materials in a program directed toward reducing fire hazards and weights in ship electrical systems. To satisfy the requirements of this program, an electrical-insulation material must withstand a 3-hour gas-flame test at 1,600 F (about 871 C). Prior to the development reported here, RP46 was rated for use at temperatures from -150 to +700 F (about -101 to 371 C), and no polymeric product - not even RP46 - was expected to withstand the Navy 3-hour gas-flame test.

Effects of copper vapour on thermophysical properties of CO2-N2 plasma

NASA Astrophysics Data System (ADS)

Zhong, Linlin; Wang, Xiaohua; Rong, Mingzhe; Cressault, Yann

2016-10-01

CO2-N2 mixtures are often used as arc quenching medium (to replace SF6) in circuit breakers and shielding gas in arc welding. In such applications, copper vapour resulting from electrode surfaces can modify characteristics of plasmas. This paper therefore presents an investigation of the effects of copper on thermophysical properties of CO2-N2 plasma. The equilibrium compositions, thermodynamic properties (including mass density, specific enthalpy, and specific heat), transport coefficients (including electrical conductivity, viscosity, and thermal conductivity), and four kinds of combined diffusion coefficients due to composition gradients, applied electric fields, temperature gradients, and pressure gradients respectively, were calculated and discussed for CO2-N2 (mixing ratio 7:3) plasma contaminated by different proportions of copper vapour. The significant influences of copper were observed on all the properties of CO2-N2-Cu mixtures. The better ionization ability and larger molar mass of copper and larger collision integrals related to copper, should be responsible for such influences.

Ion Channels in the Heart

PubMed Central

Bartos, Daniel C.; Grandi, Eleonora; Ripplinger, Crystal M.

2015-01-01

Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally-determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy. PMID:26140724

Effect of nanocomposite gate-dielectric properties on pentacene microstructure and field-effect transistor characteristics.

PubMed

Lee, Wen-Hsi; Wang, Chun-Chieh

2010-02-01

In this study, the effect of surface energy and roughness of the nanocomposite gate dielectric on pentacene morphology and electrical properties of pentacene OTFT are reported. Nanoparticles TiO2 were added in the polyimide matrix to form a nanocomposite which has a significantly different surface characteristic from polyimide, leading to a discrepancy in the structural properties of pentacene growth. A growth mode of pentacene deposited on the nanocomposite is proposed to explain successfully the effect of surface properties of nanocomposite gate dielectric such as surface energy and roughness on the pentacene morphology and electrical properties of OTFT. To obtain the lower surface energy and smoother surface of nanocomposite gate dielectric that is responsible for the desired crystalline, microstructure of pentacene and electrical properties of device, a bottom contact OTFT-pentacene deposited on the double-layer nanocomposite gate dielectric consisting of top smoothing layer of the neat polyimide and bottom layer of (PI+ nano-TiO2 particles) nanocomposite has been successfully demonstrated to exhibit very promising performance including high current on to off ratio of about 6 x 10(5), threshold voltage of -10 V and moderately high filed mobility of 0.15 cm2V(-1)s(-1).

Thermophysical Properties of Five Industrial Steels in the Solid and Liquid Phase

NASA Astrophysics Data System (ADS)

Wilthan, B.; Schützenhöfer, W.; Pottlacher, G.

2017-07-01

The need for characterization of thermophysical properties of steel was addressed in the FFG-Bridge Project 810999 in cooperation with our partner from industry, Böhler Edelstahl GmbH & Co KG. To optimize numerical simulations of production processes such as plastic deformation or remelting, additional and more accurate thermophysical property data were necessary for the group of steels under investigation. With the fast ohmic pulse heating circuit system and a commercial high-temperature Differential Scanning Calorimeter at Graz University of Technology, we were able to measure the temperature-dependent specific electrical resistivity and specific enthalpy for a set of five high alloyed steels: E105, M314, M315, P800, and V320 from room temperature up into the liquid phase. The mechanical properties of those steels make sample preparation an additional challenge. The described experimental approach typically uses electrically conducting wire-shaped specimen with a melting point high enough for the implemented pyrometric temperature measurement. The samples investigated here are too brittle to be drawn as wires and could only be cut into rectangular specimen by Electrical Discharge Machining. Even for those samples all electrical signals and the temperature signal can be recorded with proper alignment of the pyrometer. For each material under investigation, a set of data including chemical composition, solidus and liquidus temperature, enthalpy, electrical resistivity, and thermal diffusivity as a function of temperature will be reported.

Making Better Scar: Emerging Approaches for Modifying Mechanical and Electrical Properties Following Infarction and Ablation

PubMed Central

Holmes, Jeffrey W.; Laksman, Zachary; Gepstein, Lior

2015-01-01

Following myocardial infarction (MI), damaged myocytes are replaced by collagenous scar tissue, which serves an important mechanical function – maintaining integrity of the heart wall against enormous mechanical forces – but also disrupts electrical function as structural and electrical remodeling in the infarct and borderzone predispose to re-entry and ventricular tachycardia. Novel emerging regenerative approaches aim to replace this scar tissue with viable myocytes. Yet an alternative strategy of therapeutically modifying selected scar properties may also prove important, and in some cases may offer similar benefits with lower risk or regulatory complexity. Here, we review potential goals for such modifications as well as recent proof-of-concept studies employing specific modifications, including gene therapy to locally increase conduction velocity or prolong the refractory period in and around the infarct scar, and modification of scar anisotropy to improve regional mechanics and pump function. Another advantage of scar modification techniques is that they have applications well beyond MI. In particular, ablation treats electrical abnormalities of the heart by intentionally generating scar to block aberrant conduction pathways. Yet in diseases such as atrial fibrillation (AF) where ablation can be extensive, treating the electrical disorder can significantly impair mechanical function. Creating smaller, denser scars that more effectively block conduction, and choosing the location of those lesions by balancing their electrical and mechanical impacts, could significantly improve outcomes for AF patients. We review some recent advances in this area, including the use of computational models to predict the mechanical effects of specific lesion sets and gene therapy for functional ablation. Overall, emerging techniques for modifying scar properties represents a potentially important important set of tools for improving patient outcomes across a range of heart diseases, whether used in place of or as an adjunct to regenerative approaches. PMID:26615948

Spatially resolved imaging of opto-electrical property variations

DOEpatents

Nikiforov, Maxim; Darling, Seth B; Suzer, Ozgun; Guest, Jeffrey; Roelofs, Andreas

2014-09-16

Systems and methods for opto electric properties are provided. A light source illuminates a sample. A reference detector senses light from the light source. A sample detector receives light from the sample. A positioning fixture allows for relative positioning of the sample or the light source with respect to each other. An electrical signal device measures the electrical properties of the sample. The reference detector, sample detector and electrical signal device provide information that may be processed to determine opto-electric properties of the same.

The Effect of Particles on Electrolytically Polymerized Thin Natural MCF Rubber for Soft Sensors Installed in Artificial Skin

PubMed Central

Shimada, Kunio; Mochizuki, Osamu; Kubota, Yoshihiro

2017-01-01

The aim of this study is to investigate the effect of particles as filler in soft rubber sensors installed in artificial skin. We examine sensors made of natural rubber (NR-latex) that include magnetic particles of Ni and Fe3O4 using magnetic compound fluid (MCF). The 1-mm thickness of the electrolytically polymerized MCF rubber makes production of comparatively thin rubber sensors feasible. We first investigate the effect of magnetic particles Ni and Fe3O4 on the curing of MCF rubber. Next, in order to adjust the electric properties of the MCF rubber, we adopt Al2O3 dielectric particles. We investigate the effect of Al2O3 particles on changes in electric current, voltage and temperature of electrolytically polymerized MCF rubber liquid, and on the electric properties under the application of normal and shear forces. By adjusting the ratio of Ni, Fe3O4, Al2O3 and water in MCF rubber with Al2O3, it is possible to change the electric properties. PMID:28422061

Temperature Dependent Electrical Transport Properties of Ni-Cr and Co-Cr Binary Alloys

NASA Astrophysics Data System (ADS)

Thakore, B. Y.; Suthar, P. H.; Khambholja, S. G.; Gajjar, P. N.; Bhatt, N. K.; Jani, A. R.

2011-12-01

The temperature dependent electrical transport properties viz. electrical resistivity and thermal conductivity of Ni10Cr90 and Co20Cr80 alloys are computed at various temperatures. The electrical resistivity has been calculated according to Faber-Ziman model combined with Ashcroft-Langreth partial structure factors. In the present work, to include the ion-electron interaction, we have used a well tested local model potential. For exchange-correlation effects, five different forms of local field correction functions due to Hartree (H), Taylor (T), Ichimaru and Utsumi (IU), Farid et al (F) and Sarkar et al (S) are used. The present results due to S function are in good agreement with the experimental data as compared to results obtained using other four functions. The S functions satisfy compressibility sum rule in long wave length limit more accurately as compared to T, IU and F functions, which may be responsible for better agreement of results, obtained using S function. Also, present result confirms the validity of present approach in determining the transport properties of alloys like Ni-Cr and Co-Cr.

Scalable fabrication of a hybrid field-effect and acousto-electric device by direct growth of monolayer MoS2/LiNbO3

PubMed Central

Preciado, Edwin; Schülein, Florian J.R.; Nguyen, Ariana E.; Barroso, David; Isarraraz, Miguel; von Son, Gretel; Lu, I-Hsi; Michailow, Wladislaw; Möller, Benjamin; Klee, Velveth; Mann, John; Wixforth, Achim; Bartels, Ludwig; Krenner, Hubert J.

2015-01-01

Lithium niobate is the archetypical ferroelectric material and the substrate of choice for numerous applications including surface acoustic wave radio frequencies devices and integrated optics. It offers a unique combination of substantial piezoelectric and birefringent properties, yet its lack of optical activity and semiconducting transport hamper application in optoelectronics. Here we fabricate and characterize a hybrid MoS2/LiNbO3 acousto-electric device via a scalable route that uses millimetre-scale direct chemical vapour deposition of MoS2 followed by lithographic definition of a field-effect transistor structure on top. The prototypical device exhibits electrical characteristics competitive with MoS2 devices on silicon. Surface acoustic waves excited on the substrate can manipulate and probe the electrical transport in the monolayer device in a contact-free manner. We realize both a sound-driven battery and an acoustic photodetector. Our findings open directions to non-invasive investigation of electrical properties of monolayer films. PMID:26493867

A dielectrophoresis-impedance method for protein detection and analysis

NASA Astrophysics Data System (ADS)

Mohamad, Ahmad Sabry; Hamzah, Roszymah; Hoettges, Kai F.; Hughes, Michael Pycraft

2017-01-01

Dielectrophoresis (DEP) has increasingly been used for the assessment of the electrical properties of molecular scale objects including proteins, DNA, nanotubes and nanowires. However, whilst techniques have been developed for the electrical characterisation of frequency-dependent DEP response, biomolecular study is usually limited to observation using fluorescent markers, limiting its applicability as a characterisation tool. In this paper we present a label-free, impedance-based method of characterisation applied to the determination of the electrical properties of colloidal protein molecules, specifically Bovine Serum Albumin (BSA). By monitoring the impedance between electrodes as proteins collect, it is shown to be possible to observe multi-dispersion behaviour. A DEP dispersion exhibited at 400 kHz is attributable to the orientational dispersion of the molecule, whilst a second, higher-frequency dispersion is attributed to a Maxwell-Wagner type dispersion; changes in behaviour with medium conductivity suggest that this is strongly influenced by the electrical double layer surrounding the molecule.

Advances in imaging and quantification of electrical properties at the nanoscale using Scanning Microwave Impedance Microscopy (sMIM)

NASA Astrophysics Data System (ADS)

Friedman, Stuart; Yang, Yongliang; Amster, Oskar

2015-03-01

Scanning Microwave Impedance Microscopy (sMIM) is a mode for Atomic Force Microscopy (AFM) enabling imaging of unique contrast mechanisms and measurement of local permittivity and conductivity at the 10's of nm length scale. Recent results will be presented illustrating high-resolution electrical features such as sub 15 nm Moire' patterns in Graphene, carbon nanotubes of various electrical states and ferro-electrics. In addition to imaging, the technique is suited to a variety of metrology applications where specific physical properties are determined quantitatively. We will present research activities on quantitative measurements using multiple techniques to determine dielectric constant (permittivity) and conductivity (e.g. dopant concentration) for a range of materials. Examples include bulk dielectrics, low-k dielectric thin films, capacitance standards and doped semiconductors. Funded in part by DOE SBIR DE-SC0009586.

Ceramic Processing

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

EWSUK,KEVIN G.

1999-11-24

Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referredmore » to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.« less

International Congress on Glass XII (in several languages)

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

Doremus, R H; LaCourse, W C; Mackenzie, J D

1980-01-01

A total of 158 papers are included under nine headings: structure and glass formation; optical properties; electrical and magnetic properties; mechanical properties and relaxation; mass transport; chemical durability and surfaces; nucleation; crystallization; and glass ceramics; processing; and automatic controls. Separate abstracts were prepared for eight papers; four of the remaining papers had been processed previously for the data base. (DLC)

Modeling of electrical impedance tomography to detect breast cancer by finite volume methods

NASA Astrophysics Data System (ADS)

Ain, K.; Wibowo, R. A.; Soelistiono, S.

2017-05-01

The properties of the electrical impedance of tissue are an interesting study, because changes of the electrical impedance of organs are related to physiological and pathological. Both physiological and pathological properties are strongly associated with disease information. Several experiments shown that the breast cancer has a lower impedance than the normal breast tissue. Thus, the imaging based on impedance can be used as an alternative equipment to detect the breast cancer. This research carries out by modelling of Electrical Impedance Tomography to detect the breast cancer by finite volume methods. The research includes development of a mathematical model of the electric potential field by 2D Finite Volume Method, solving the forward problem and inverse problem by linear reconstruction method. The scanning is done by 16 channel electrode with neighbors method to collect data. The scanning is performed at a frequency of 10 kHz and 100 kHz with three objects numeric includes an anomaly at the surface, an anomaly at the depth and an anomaly at the surface and at depth. The simulation has been successfully to reconstruct image of functional anomalies of the breast cancer at the surface position, the depth position or a combination of surface and the depth.

Assembly for electrical conductivity measurements in the piston cylinder device

DOEpatents

Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

2012-06-05

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

Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires.

PubMed

Araneo, Rodolfo; Rinaldi, Antonio; Notargiacomo, Andrea; Bini, Fabiano; Pea, Marialilia; Celozzi, Salvatore; Marinozzi, Franco; Lovat, Giampiero

2014-12-08

Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy) characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews.

Design Concepts, Fabrication and Advanced Characterization Methods of Innovative Piezoelectric Sensors Based on ZnO Nanowires

PubMed Central

Araneo, Rodolfo; Rinaldi, Antonio; Notargiacomo, Andrea; Bini, Fabiano; Pea, Marialilia; Celozzi, Salvatore; Marinozzi, Franco; Lovat, Giampiero

2014-01-01

Micro- and nano-scale materials and systems based on zinc oxide are expected to explode in their applications in the electronics and photonics, including nano-arrays of addressable optoelectronic devices and sensors, due to their outstanding properties, including semiconductivity and the presence of a direct bandgap, piezoelectricity, pyroelectricity and biocompatibility. Most applications are based on the cooperative and average response of a large number of ZnO micro/nanostructures. However, in order to assess the quality of the materials and their performance, it is fundamental to characterize and then accurately model the specific electrical and piezoelectric properties of single ZnO structures. In this paper, we report on focused ion beam machined high aspect ratio nanowires and their mechanical and electrical (by means of conductive atomic force microscopy) characterization. Then, we investigate the suitability of new power-law design concepts to accurately model the relevant electrical and mechanical size-effects, whose existence has been emphasized in recent reviews. PMID:25494351

Relativistic calculations of atomic properties

NASA Astrophysics Data System (ADS)

Kaur, Jasmeet; Sahoo, B. K.; Arora, Bindiya

2017-04-01

Singly charged ions are engaging candidates in many areas of Physics. They are especially important in astrophysics for evaluating the radiative properties of stellar objects, in optical frequency standards and for fundamental physics studies such as searches for permanent electric dipole moments and atomic parity violation. Interpretation of these experiments often requires a knowledge of their transition wavelengths and electric dipole amplitudes. In this work, we discuss the calculation of various properties of alkaline earth ions. The relativistic all-order SD method in which all single and double excitations of the Dirac-Fock wave function are included, is used to calculate these atomic properties. We use this method for evaluation of electric dipole matrix elements of alkaline earth ions. Combination of these matrix elements with experimental energies allow to obtain the polarizabilities of ground and excited states of ions. We discuss the applications of estimated polarizabiities as a function of imaginary frequencies in the calculations of long-range atom-ion interactions. We have also located the magic wavelengths for nS1 / 2 - nD3 / 2 , 5 / 2 transitions of alkaline earth ions. These calculated properties will be highly valuable to atomic and astrophysics community. UGC-BSR Grant No. F.7-273/2009/BSR.

Improvement of silicone rubber properties by addition of nano-SiO2 particles.

PubMed

Wu, Lianfeng; Wang, Xianming; Ning, Liang; Han, Jianjun; Wan, Zhong; Lu, Min

2016-07-04

To improve the comprehensive performances of a one-part room temperature vulcanized silicone rubber(RTV-1 SiR), Nano-SiO2 particles are employed as the reinforcing agent. The SiO2/RTV-1 SiR composite is prepared using PDMS, ND42, D-60 and HMDS-modified SiO2 particles by mixing method. And then, the mechanical and electrical properties, including shear strength, tensile strength, hardness Shore A and volume resistivity, are investigated using experimental method. The addition of nano-SiO2 particles can improve the properties of the SiO2/RTV-1 SiR composite in different degrees. And, the incorporation of 25~30 phr nano-SiO2 particles is found to be reasonable for silicone rubber composite with the best comprehensive performances. The significant improvement of mechanical properties and electrical insulation of SiO2 may be contributed to the addition of modified nano-SiO2 particles. Additionally, the excellent comprehensive performances of SiO2/RTV-1 SiR composite guarantee a potential applications as electrical-insulating adhesives.

Thermoelectric properties of p-type perovskite compounds LaCoO3 systems containing the A-site vacancy

NASA Astrophysics Data System (ADS)

Anzai, Mayuka; Kawakami, Hiroshi; Saito, Miwa; Yamamura, Hiroshi

2011-05-01

Thermoelectric properties of Sr-doped LaCoO3 system which includes both La1-xSrxCoO3 and La0.95-xSrxsquare0.05CoO3 containing the A-site vacancy were prepared by solid state reaction. The crystal phases of the samples were investigated by X-ray diffraction method. The electrical conductivity, Seebeck coefficient, and thermal conductivity were investigated, focusing the effect of A-site vacancy. Doping of Sr to LaCoO3 improved the electrical conductivity but decreased the seebeck coefficient and increased the thermal conductivity. A-site vacancy of La0.95-xSrxsquare0.05CoO3 system, in comparison with La1-xSrxCoO3 system, increased electrical conductivity, and decreased lattice thermal conductivity. As a result, it was found that the thermoelectric properties of La0.95-xSrxsquare0.05CoO3 containing the A-site vacancy showed the higher values than those of La1-xSrxCoO3. The introduction of A-site vacancy was effective on the improvement of thermoelectric property.

Proceedings of the International Symposium on the Structure and Properties of Dislocations in Semiconductors (6th) held in Oxford (England) 5-8 April 1989: Structure and Properties of Dislocations in Semiconductors 1989

DTIC Science & Technology

1989-04-08

now good experimental data on the effects of impurities, including locking by non-electrical xii Preface impurities, and the effect of electrically... locks which result from the interaction of the gliding dislocations. As a matter of fact, these dislocation configurations look similar to those...loop on the go° partial. Structure of grain boundaries and dislocations 3 2.2. Lomer-Cottrell lock : a/2>. Two 60’ dislocations can react and give

CNF Re-Inforced Polymer Composites

NASA Astrophysics Data System (ADS)

Lake, Max L.; Tibbetts, Gary G.; Glasgow, D. Gerald

2004-09-01

In properties of physical size, performance improvement, and production cost, carbon nanofiber (CNF) lies in a spectrum of materials bounded by carbon black, fullerenes, and single wall to multi-wall carbon nanotubes on one end and continuous carbon fiber on the other. Results show promise for use of CNF for modified electrical conductivity of polymer composites. Current compounding efforts focus on techniques for nanofiber dispersion designed to retain nanofiber length, including de-bulking methods and low shear melt processing. Heat treatment of CNF as a postproduction process has also been evaluated for its influence on electrical properties of CNF-reinforced polymer composites.

Multiscale properties of unconventional reservoir rocks

NASA Astrophysics Data System (ADS)

Woodruff, W. F.

A multidisciplinary study of unconventional reservoir rocks is presented, providing the theory, forward modeling and Bayesian inverse modeling approaches, and laboratory protocols to characterize clay-rich, low porosity and permeability shales and mudstones within an anisotropic framework. Several physical models characterizing oil and gas shales are developed across multiple length scales, ranging from microscale phenomena, e.g. the effect of the cation exchange capacity of reactive clay mineral surfaces on water adsorption isotherms, and the effects of infinitesimal porosity compaction on elastic and electrical properties, to meso-scale phenomena, e.g. the role of mineral foliations, tortuosity of conduction pathways and the effects of organic matter (kerogen and hydrocarbon fractions) on complex conductivity and their connections to intrinsic electrical anisotropy, as well as the macro-scale electrical and elastic properties including formulations for the complex conductivity tensor and undrained stiffness tensor within the context of effective stress and poroelasticity. Detailed laboratory protocols are described for sample preparation and measurement of these properties using spectral induced polarization (SIP) and ultrasonics for the anisotropic characterization of shales for both unjacketed samples under benchtop conditions and jacketed samples under differential loading. An ongoing study of the effects of kerogen maturation through hydrous pyrolysis on the complex conductivity is also provided in review. Experimental results are catalogued and presented for various unconventional formations in North America including the Haynesville, Bakken, and Woodford shales.

Properties of Lightning Strike Protection Coatings

NASA Astrophysics Data System (ADS)

Gagne, Martin

Composite materials are being increasingly used by many industries. In the case of aerospace companies, those materials are installed on their aircraft to save weight, and thus, fuel costs. These aircraft are lighter, but the loss of electrical conductivity makes aircraft vulnerable to lightning strikes, which hit commercial aircrafts on average once per year. This makes lightning strike protection very important, and while current metallic expanded copper foils offer good protection, they increase the weight of composites. Therefore, under the CRIAQ COMP-502 project, a team of industrial partners and academic researchers are investigating new conductive coatings with the following characteristics: High electromagnetic protection, high mechanical resistance, good environmental protection, manufacturability and moderate cost. The main objectives of this thesis, as part of this project, was to determine the main characteristics, such as electrical and tribomechanical properties, of conductive coatings on composite panels. Their properties were also to be tested after destructive tests such as current injection and environmental testing. Bombardier Aerospace provided the substrate, a composite of carbon fiber reinforced epoxy matrix, and the current commercial product, a surfacing film that includes an expanded copper foil used to compare with the other coatings. The conductive coatings fabricated by the students are: silver nanoparticles inside a binding matrix (PEDOT:PSS or a mix of Epoxy and PEDOT:PSS), silvered carbon nanofibers embedded in the surfacing film, cold sprayed tin, graphene oxide functionalized with silver nanowires, and electroless plated silver. Additionally as part of the project and thesis, magnetron sputtered aluminum coated samples were fabricated. There are three main types of tests to characterize the conductive coatings: electrical, mechanical and environmental. Electrical tests consist of finding the sheet resistance and specific resistivity of conductive coatings. Mechanical tests include adhesion, scratch, hardness and Young's modulus of the coatings. The environmental tests are temperature cycling and salt spray cycling. These basic characteristics were investigated first, but further tests also combine the categories, such as electrical tests before, during and after environmental tests, and the effects on the sample's mechanical properties after high electrical current injections. The electrical properties of the conductive coatings have improved and are very close to that of current expanded metallic foil or within an order of magnitude. The mechanical properties of most of these coatings are also good. They exhibit good adhesion, hardness, and no significant loss of flexion properties after current injections. The environmental tests are more mitigated, with some conductive coatings losing their surface conductivity, others having a small increase in specific resistivity, and some were simply unaffected. Tests such as thermogravimetric analysis, scanning electron microscope analysis of scratch tests, and optical microscope observations are included to provide additional analysis of the results of the conductive coatings. The conductive coatings were characterized and tested as part of the CRIAQ project. Lightning strike tests are required to gather further information on these conductive coatings. The main application for these coatings is for lightning strike protection of aircraft, but they can also be used for ground based lightning strike protection and general electromagnetic shielding.

Low-frequency electrical properties.

USGS Publications Warehouse

Olhoeft, G.R.

1985-01-01

In the interpretation of induced polarization data, it is commonly assumed that metallic mineral polarization dominantly or solely causes the observed response. However, at low frequencies, there is a variety of active chemical processes which involve the movement or transfer of electrical charge. Measurements of electrical properties at low frequencies (such as induced polarization) observe such movement of charge and thus monitor many geochemical processes at a distance. Examples in which this has been done include oxidation-reduction of metallic minerals such as sulfides, cation exchange on clays, and a variety of clay-organic reactions relevant to problems in toxic waste disposal and petroleum exploration. By using both the frequency dependence and nonlinear character of the complex resistivity spectrum, these reactions may be distinguished from each other and from barren or reactionless materials.-Author

17 CFR 250.80 - Definitions of terms used in rules under section 13.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., marketing, auditing, statistical, advertising, publicity, tax, research, or any other service (including... similar property (including coal, oil, or steam, but not including electric energy, natural or manufactured gas, or utility assets) which is sold, leased, or furnished, for a charge. (c) Construction means...

Review on measurement techniques of transport properties of nanowires Additions and Corrections. See DOI:10.1039/C3NR03242F Click here for additional data file.

PubMed Central

Rojo, Miguel Muñoz; Calero, Olga Caballero; Lopeandia, A. F.; Rodriguez-Viejo, J.

2013-01-01

Physical properties at the nanoscale are novel and different from those in bulk materials. Over the last few decades, there has been an ever growing interest in the fabrication of nanowire structures for a wide variety of applications including energy generation purposes. Nevertheless, the study of their transport properties, such as thermal conductivity, electrical conductivity or Seebeck coefficient, remains an experimental challenge. For instance, in the particular case of nanostructured thermoelectrics, theoretical calculations have shown that nanowires offer a promising way of enhancing the hitherto low efficiency of these materials in the conversion of temperature differences into electricity. Therefore, within the thermoelectrical community there has been a great experimental effort in the measurement of these quantities in actual nanowires. The measurements of these properties at the nanoscale are also of interest in fields other than energy, such as electrical components for microchips, field effect transistors, sensors, and other low scale devices. For all these applications, knowing the transport properties is mandatory. This review deals with the latest techniques developed to perform the measurement of these transport properties in nanowires. A thorough overview of the most important and modern techniques used for the characterization of different kinds of nanowires will be shown. PMID:24113712

A Preliminary Investigation of Hall Thruster Technology

NASA Technical Reports Server (NTRS)

Gallimore, Alec D.

1997-01-01

A three-year, NASA/BMDO-sponsored experimental program to conduct performance and plume plasma property measurements on two Russian Stationary Plasma Thrusters (SPTs) has been completed. The program utilized experimental facilitates at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL). The main features of the proposed effort were as follows: We Characterized Hall thruster [and arcjet] performance by measuring ion exhaust velocity with probes at various thruster conditions. Used a variety of probe diagnostics in the thruster plume to measure plasma properties and flow properties including T(sub e) and n(sub e), ion current density and ion energy distribution, and electric fields by mapping plasma potential. Used emission spectroscopy to identify species within the plume and to measure electron temperatures.

Silylene-diethynyl-arylene polymers having liquid crystalline properties

DOEpatents

Barton, Thomas J.; Ding, Yiwei

1993-09-07

The present invention provides linear organosilicon polymers including diethynyl-(substituted)arylene units, and a process for their preparation. These novel polymers possess useful properties including electrical conductivity, liquid crystallinity, and/or photoluminescence. These polymers possess good solubility in organic solvents. A preferred example is produced according to the following reaction scheme. ##STR1## These polymers can be solvent-cast to yield excellent films and can also be pulled into fibers from concentrated solutions. All possess substantial crystallinity as revealed by DSC analysis and observation through a polarizing microscope, and possess liquid crystalline properties.

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

Hermeston, Mark W.

BPA proposes total vegetation management (bareground) in the electrical substations, and, noxious weed management and maintenance of landscaping within the property boundaries of the listed facilities. These facilities are all located within the Covington District of the Snohomish Region. BPA proposes to manage vegetation inside and around electrical substations and associated facilities. Vegetation management within the substations will include bareground management by herbicides of all areas within the fenced perimeter of the facility including a bareground zone of up to 3 meters (10 feet) outside of the fenced area. The management of vegetation outside the substation and associated facilities willmore » include: 1) bare ground management of perimeter roads and parking areas; 2) control of noxious weeds throughout property boundaries; 3) mowing, fertilizing, and weed control of landscaped lawn and mulched areas; 4) weed control in ornamental shrub areas; and 5) areas requiring only mechanical control to manage unwanted/danger trees, grasses, and shrubs.« less

Electrical properties of epoxies used in hybrid microelectronics

NASA Technical Reports Server (NTRS)

Stout, C. W.

1976-01-01

The electrical properties and basic characteristics of the structure of conductive epoxies were studied. The results of the experimental work performed to measure the electrical properties of epoxies are presented.

Batteries and fuel cells for emerging electric vehicle markets

NASA Astrophysics Data System (ADS)

Cano, Zachary P.; Banham, Dustin; Ye, Siyu; Hintennach, Andreas; Lu, Jun; Fowler, Michael; Chen, Zhongwei

2018-04-01

Today's electric vehicles are almost exclusively powered by lithium-ion batteries, but there is a long way to go before electric vehicles become dominant in the global automotive market. In addition to policy support, widespread deployment of electric vehicles requires high-performance and low-cost energy storage technologies, including not only batteries but also alternative electrochemical devices. Here, we provide a comprehensive evaluation of various batteries and hydrogen fuel cells that have the greatest potential to succeed in commercial applications. Three sectors that are not well served by current lithium-ion-powered electric vehicles, namely the long-range, low-cost and high-utilization transportation markets, are discussed. The technological properties that must be improved to fully enable these electric vehicle markets include specific energy, cost, safety and power grid compatibility. Six energy storage and conversion technologies that possess varying combinations of these improved characteristics are compared and separately evaluated for each market. The remainder of the Review briefly discusses the technological status of these clean energy technologies, emphasizing barriers that must be overcome.

Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

NASA Technical Reports Server (NTRS)

Peterson, G.P. (Bud) (Inventor); Hong, Haiping (Inventor); Salem, David R. (Inventor)

2016-01-01

Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

Temperature Modulation of Electric Fields in Biological Matter

PubMed Central

Daniels, Charlotte S.; Rubinsky, Boris

2011-01-01

Pulsed electric fields (PEF) have become an important minimally invasive surgical technology for various applications including genetic engineering, electrochemotherapy and tissue ablation. This study explores the hypothesis that temperature dependent electrical parameters of tissue can be used to modulate the outcome of PEF protocols, providing a new means for controlling and optimizing this minimally invasive surgical procedure. This study investigates two different applications of cooling temperatures applied during PEF. The first case utilizes an electrode which simultaneously delivers pulsed electric fields and cooling temperatures. The subsequent results demonstrate that changes in electrical properties due to temperature produced by this configuration can substantially magnify and confine the electric fields in the cooled regions while almost eliminating electric fields in surrounding regions. This method can be used to increase precision in the PEF procedure, and eliminate muscle contractions and damage to adjacent tissues. The second configuration considered introduces a third probe that is not electrically active and only applies cooling boundary conditions. This second study demonstrates that in this probe configuration the temperature induced changes in electrical properties of tissue substantially reduce the electric fields in the cooled regions. This novel treatment can potentially be used to protect sensitive tissues from the effect of the PEF. Perhaps the most important conclusion of this investigation is that temperature is a powerful and accessible mechanism to modulate and control electric fields in biological tissues and can therefore be used to optimize and control PEF treatments. PMID:21695144

Apparatus and method for measuring the Seebeck coefficient and resistivity of materials

NASA Technical Reports Server (NTRS)

Hadek, V. (Inventor)

1973-01-01

An apparatus for measuring the thermoelectric properties of materials under high pressure is described that includes a pair of force transmitting assemblies constructed of thermally and electrically conductive material positioned between the ram and anvil of a press. Each force transmitting assembly has a small diameter pressing portion for contacting a face of the sample so that the sample can be squeezed between them. Each assembly also includes a heat exchanger to maintain the sample face at a controlled temperature, and an electrical conductor to carry current generated by the sample. A sleeve of thermally and electrically insulative material closely surrounds the pressing portions of the two assemblies.

Soft exfoliation of 2D SnO with size-dependent optical properties

NASA Astrophysics Data System (ADS)

Singh, Mandeep; Della Gaspera, Enrico; Ahmed, Taimur; Walia, Sumeet; Ramanathan, Rajesh; van Embden, Joel; Mayes, Edwin; Bansal, Vipul

2017-06-01

Two-dimensional (2D) materials have recently gained unprecedented attention as potential candidates for next-generation (opto)electronic devices due to their fascinating optical and electrical properties. Tin monoxide, SnO, is an important p-type semiconductor with applications across photocatalysis (water splitting) and electronics (transistors). However, despite its potential in several important technological applications, SnO remains underexplored in its 2D form. Here we present a soft exfoliation strategy to produce 2D SnO nanosheets with tunable optical and electrical properties. Our approach involves the initial synthesis of layered SnO microspheres, which are readily exfoliated through a low-power sonication step to form high quality SnO nanosheets. We demonstrate that the properties of 2D SnO are strongly dependent on its dimensions. As verified through optical absorption and photoluminescence studies, a strong size-dependent quantum confinement effect in 2D SnO leads to substantial variation in its optical and electrical properties. This results in a remarkable (>1 eV) band gap widening in atomically thin SnO. Through photoconductivity measurements, we further validate a strong correlation between the quantum-confined properties of 2D SnO and the selective photoresponse of atomically thin sheets in the high energy UV light. Such tunable semiconducting properties of 2D SnO could be exploited for a variety of applications including photocatalysis, photovoltaics and optoelectronics in general.

Temperature Dependent Electrical Transport Properties of Ni-Cr and Co-Cr Binary Alloys

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

Thakore, B. Y.; Khambholja, S. G.; Bhatt, N. K.

2011-12-12

The temperature dependent electrical transport properties viz. electrical resistivity and thermal conductivity of Ni{sub 10}Cr{sub 90} and Co{sub 20}Cr{sub 80} alloys are computed at various temperatures. The electrical resistivity has been calculated according to Faber-Ziman model combined with Ashcroft-Langreth partial structure factors. In the present work, to include the ion-electron interaction, we have used a well tested local model potential. For exchange-correlation effects, five different forms of local field correction functions due to Hartree (H), Taylor (T), Ichimaru and Utsumi (IU), Farid et al (F) and Sarkar et al (S) are used. The present results due to S function aremore » in good agreement with the experimental data as compared to results obtained using other four functions. The S functions satisfy compressibility sum rule in long wave length limit more accurately as compared to T, IU and F functions, which may be responsible for better agreement of results, obtained using S function. Also, present result confirms the validity of present approach in determining the transport properties of alloys like Ni-Cr and Co-Cr.« less

Thermodynamic properties and transport coefficients of two-temperature helium thermal plasmas

NASA Astrophysics Data System (ADS)

Guo, Xiaoxue; Murphy, Anthony B.; Li, Xingwen

2017-03-01

Helium thermal plasmas are in widespread use in arc welding and many other industrial applications. Simulation of these processes relies on accurate plasma property data, such as plasma composition, thermodynamic properties and transport coefficients. Departures from LTE (local thermodynamic equilibrium) generally occur in some regions of helium plasmas. In this paper, properties are calculated allowing for different values of the electron temperature, T e, and heavy-species temperature, T h, at atmospheric pressure from 300 K to 30 000 K. The plasma composition is first calculated using the mass action law, and the two-temperature thermodynamic properties are then derived. The viscosity, diffusion coefficients, electrical conductivity and thermal conductivity of the two-temperature helium thermal plasma are obtained using a recently-developed method that retains coupling between electrons and heavy species by including the electron-heavy-species collision term in the heavy-species Boltzmann equation. It is shown that the viscosity and the diffusion coefficients strongly depend on non-equilibrium ratio θ (θ ={{T}\\text{e}}/{{T}\\text{h}} ), through the plasma composition and the collision integrals. The electrical conductivity, which depends on the electron number density and ordinary diffusion coefficients, and the thermal conductivity have similar dependencies. The choice of definition of the Debye length is shown to affect the electrical conductivity significantly for θ  >  1. By comparing with literature data, it is shown that the coupling between electrons and heavy species has a significant influence on the electrical conductivity, but not on the viscosity. Plasma properties are tabulated in the supplementary data.

Electrical properties of granite with implications for the lower crust.

USGS Publications Warehouse

Olhoeft, G.R.

1981-01-01

The electrical properties of granite appear to be dominantly controlled by the amount of free water in the granite and by temperature. Minor contributions to the electrical properties are provided by hydrostatic and lithostatic pressure, structurally bound water, oxygen fugacity, and other parameters. The effect of sulphur fugacity may be important but is experimentally unconfirmed. In addition to changing the magnitude of electrical properties, the amount and chemistry of water in granite significantly changes the temperature dependence of the electrical properties. With increasing temperature, changes in water content retain large, but lessened, effects on electrical properties. Near room temperature, a monolayer of water will decrease the electrical resistivity by an order of magnitude. Several weight-percent water may decrease the electrical resistivity by as much as nine orders of magnitude and decrease the thermal activation energy by a factor of five. At elevated temperatures just below granitic melting, a few weight-percent water may still decrease the resistivity by as much as 3 orders of magnitude and the activation energy by a factor of two.-Author

The Global Spike: Conserved Dendritic Properties Enable Unique Ca2+ Spike Generation in Low-Threshold Spiking Neurons.

PubMed

Connelly, William M; Crunelli, Vincenzo; Errington, Adam C

2015-11-25

Low-threshold Ca(2+) spikes (LTS) are an indispensible signaling mechanism for neurons in areas including the cortex, cerebellum, basal ganglia, and thalamus. They have critical physiological roles and have been strongly associated with disorders including epilepsy, Parkinson's disease, and schizophrenia. However, although dendritic T-type Ca(2+) channels have been implicated in LTS generation, because the properties of low-threshold spiking neuron dendrites are unknown, the precise mechanism has remained elusive. Here, combining data from fluorescence-targeted dendritic recordings and Ca(2+) imaging from low-threshold spiking cells in rat brain slices with computational modeling, the cellular mechanism responsible for LTS generation is established. Our data demonstrate that key somatodendritic electrical conduction properties are highly conserved between glutamatergic thalamocortical neurons and GABAergic thalamic reticular nucleus neurons and that these properties are critical for LTS generation. In particular, the efficiency of soma to dendrite voltage transfer is highly asymmetric in low-threshold spiking cells, and in the somatofugal direction, these neurons are particularly electrotonically compact. Our data demonstrate that LTS have remarkably similar amplitudes and occur synchronously throughout the dendritic tree. In fact, these Ca(2+) spikes cannot occur locally in any part of the cell, and hence we reveal that LTS are generated by a unique whole-cell mechanism that means they always occur as spatially global spikes. This all-or-none, global electrical and biochemical signaling mechanism clearly distinguishes LTS from other signals, including backpropagating action potentials and dendritic Ca(2+)/NMDA spikes, and has important consequences for dendritic function in low-threshold spiking neurons. Low-threshold Ca(2+) spikes (LTS) are critical for important physiological processes, including generation of sleep-related oscillations, and are implicated in disorders including epilepsy, Parkinson's disease, and schizophrenia. However, the mechanism underlying LTS generation in neurons, which is thought to involve dendritic T-type Ca(2+) channels, has remained elusive due to a lack of knowledge of the dendritic properties of low-threshold spiking cells. Combining dendritic recordings, two-photon Ca(2+) imaging, and computational modeling, this study reveals that dendritic properties are highly conserved between two prominent low-threshold spiking neurons and that these properties underpin a whole-cell somatodendritic spike generation mechanism that makes the LTS a unique global electrical and biochemical signal in neurons. Copyright © 2015 Connelly et al.

Recent Advances on In Situ SEM Mechanical and Electrical Characterization of Low-Dimensional Nanomaterials.

PubMed

Jiang, Chenchen; Lu, Haojian; Zhang, Hongti; Shen, Yajing; Lu, Yang

2017-01-01

In the past decades, in situ scanning electron microscopy (SEM) has become a powerful technique for the experimental study of low-dimensional (1D/2D) nanomaterials, since it can provide unprecedented details for individual nanostructures upon mechanical and electrical stimulus and thus uncover the fundamental deformation and failure mechanisms for their device applications. In this overview, we summarized recent developments on in situ SEM-based mechanical and electrical characterization techniques including tensile, compression, bending, and electrical property probing on individual nanostructures, as well as the state-of-the-art electromechanical coupling analysis. In addition, the advantages and disadvantages of in situ SEM tests were also discussed with some possible solutions to address the challenges. Furthermore, critical challenges were also discussed for the development and design of robust in situ SEM characterization platform with higher resolution and wider range of samples. These experimental efforts have offered in-depth understanding on the mechanical and electrical properties of low-dimensional nanomaterial components and given guidelines for their further structural and functional applications.

Recent Advances on In Situ SEM Mechanical and Electrical Characterization of Low-Dimensional Nanomaterials

PubMed Central

Jiang, Chenchen; Lu, Haojian; Zhang, Hongti

2017-01-01

In the past decades, in situ scanning electron microscopy (SEM) has become a powerful technique for the experimental study of low-dimensional (1D/2D) nanomaterials, since it can provide unprecedented details for individual nanostructures upon mechanical and electrical stimulus and thus uncover the fundamental deformation and failure mechanisms for their device applications. In this overview, we summarized recent developments on in situ SEM-based mechanical and electrical characterization techniques including tensile, compression, bending, and electrical property probing on individual nanostructures, as well as the state-of-the-art electromechanical coupling analysis. In addition, the advantages and disadvantages of in situ SEM tests were also discussed with some possible solutions to address the challenges. Furthermore, critical challenges were also discussed for the development and design of robust in situ SEM characterization platform with higher resolution and wider range of samples. These experimental efforts have offered in-depth understanding on the mechanical and electrical properties of low-dimensional nanomaterial components and given guidelines for their further structural and functional applications. PMID:29209445

Improved high modulus carbon fibers. [elimination of hazards due to electrical properties

NASA Technical Reports Server (NTRS)

Ansell, G. S.; Chen, S. H.; Diffendorf, R. J.; Kim, C. M.; Lemaistre, C. W.; Lyman, C. E.; Shen, T. H.; Wang, J. J. H.

1979-01-01

Carbon fibers which are electrically insulating but still maintain the mechanical properties of the original carbon fibers were investigated. Three approaches were taken to increase the electrical resistance of carbon fibers: (1) boron nitride (BN) coatings; (2) doping of carbon fibers to alter their electrical properties; and (3) low temperature final heat treatment. The structure of carbon fibers and its effect upon properties was also studied. Results are presented.

Magnetic Resonance-Based Electrical Property Tomography (MR-EPT) for Prostate Cancer Grade Imaging

DTIC Science & Technology

2016-07-01

Award Number: W81XWH-13-1-0127 TITLE: Magnetic Resonance-Based Electrical Property Tomography (MR- EPT) for Prostate Cancer Grade Imaging...SUBTITLE 5a. CONTRACT NUMBER W81XWH-13-1-0127 Magnetic Resonance-Based Electrical Property Tomography (MR- EPT) for Prostate Cancer Grade Imaging...developing Magnetic Resonance – Electrical Property Tomography (MR-EPT) specifically for prostate imaging. MR-EPT is an imaging modality that may enable

3D noninvasive ultrasound Joule heat tomography based on acousto-electric effect using unipolar pulses: a simulation study

PubMed Central

Yang, Renhuan; Li, Xu; Song, Aiguo; He, Bin; Yan, Ruqiang

2012-01-01

Electrical properties of biological tissues are highly sensitive to their physiological and pathological status. Thus it is of importance to image electrical properties of biological tissues. However, spatial resolution of conventional electrical impedance tomography (EIT) is generally poor. Recently, hybrid imaging modalities combining electric conductivity contrast and ultrasonic resolution based on acouto-electric effect has attracted considerable attention. In this study, we propose a novel three-dimensional (3D) noninvasive ultrasound Joule heat tomography (UJHT) approach based on acouto-electric effect using unipolar ultrasound pulses. As the Joule heat density distribution is highly dependent on the conductivity distribution, an accurate and high resolution mapping of the Joule heat density distribution is expected to give important information that is closely related to the conductivity contrast. The advantages of the proposed ultrasound Joule heat tomography using unipolar pulses include its simple inverse solution, better performance than UJHT using common bipolar pulses and its independence of any priori knowledge of the conductivity distribution of the imaging object. Computer simulation results show that using the proposed method, it is feasible to perform a high spatial resolution Joule heat imaging in an inhomogeneous conductive media. Application of this technique on tumor scanning is also investigated by a series of computer simulations. PMID:23123757

Electrical and chemical properties of XeCl*(308 nm) exciplex lamp created by a dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Baadj, S.; Harrache, Z.; Belasri, A.

2013-12-01

The aim of this work is to highlight, through numerical modeling, the chemical and the electrical characteristics of xenon chloride mixture in XeCl* (308 nm) excimer lamp created by a dielectric barrier discharge. A temporal model, based on the Xe/Cl2 mixture chemistry, the circuit and the Boltzmann equations, is constructed. The effects of operating voltage, Cl2 percentage in the Xe/Cl2 gas mixture, dielectric capacitance, as well as gas pressure on the 308-nm photon generation, under typical experimental operating conditions, have been investigated and discussed. The importance of charged and excited species, including the major electronic and ionic processes, is also demonstrated. The present calculations show clearly that the model predicts the optimal operating conditions and describes the electrical and chemical properties of the XeCl* exciplex lamp.

[Modeling and experimental study on frequency-domain electricity properties of biological materials].

PubMed

Tian, Hua; Luo, Shiqiang; Zhang, Rui; Yang, Gang; Huang, Hua

2009-12-01

Frequency-domain electricity properties of four objects, including bullfrog skin, bullfrog muscle, triply distilled water and 0.9% NaCl, were tested in the range of 100Hz-10MHz using home-made electrode and measuring system. The experimental results showed that the resistance of 0.9% NaCl decreased dramatically, that the amplitude frequency characteristics of bullfrog's muscle and skin were similar, but that of triply distilled water did not change significantly. The frequency dependence of 0.9% NaCl showed that the electrode had great influence on the measuring system, so a new equivalent circuit model based on the electrode system was needed. These findings suggest that the new five-parameter equivalent circuit model, which embodies considerations on the interaction between electrodes and tissues, is a reasonable equivalent circuit for studying the electrical characteristics of biological materials.

Nanomaterials for Space Exploration Applications

NASA Technical Reports Server (NTRS)

Moloney, Padraig G.

2006-01-01

Nano-engineered materials are multi-functional materials with superior mechanical, thermal and electrical properties. Nanomaterials may be used for a variety of space exploration applications, including ultracapacitors, active/passive thermal management materials, and nanofiltration for water recovery. Additional applications include electrical power/energy storage systems, hybrid systems power generation, advanced proton exchange membrane fuel cells, and air revitalization. The need for nanomaterials and their growth, characterization, processing and space exploration applications is discussed. Data is presented for developing solid-supported amine adsorbents based on carbon nanotube materials and functionalization of nanomaterials is examined.

Gradient-based Electrical Properties Tomography (gEPT): a Robust Method for Mapping Electrical Properties of Biological Tissues In Vivo Using Magnetic Resonance Imaging

PubMed Central

Liu, Jiaen; Zhang, Xiaotong; Schmitter, Sebastian; Van de Moortele, Pierre-Francois; He, Bin

2014-01-01

Purpose To develop high-resolution electrical properties tomography (EPT) methods and investigate a gradient-based EPT (gEPT) approach which aims to reconstruct the electrical properties (EP), including conductivity and permittivity, of an imaged sample from experimentally measured B1 maps with improved boundary reconstruction and robustness against measurement noise. Theory and Methods Using a multi-channel transmit/receive stripline head coil, with acquired B1 maps for each coil element, by assuming negligible Bz component compared to transverse B1 components, a theory describing the relationship between B1 field, EP value and their spatial gradient has been proposed. The final EP images were obtained through spatial integration over the reconstructed EP gradient. Numerical simulation, physical phantom and in vivo human experiments at 7 T have been conducted to evaluate the performance of the proposed methods. Results Reconstruction results were compared with target EP values in both simulations and phantom experiments. Human experimental results were compared with EP values in literature. Satisfactory agreement was observed with improved boundary reconstruction. Importantly, the proposed gEPT method proved to be more robust against noise when compared to previously described non-gradient-based EPT approaches. Conclusion The proposed gEPT approach holds promises to improve EP mapping quality by recovering the boundary information and enhancing robustness against noise. PMID:25213371

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.

Electromechanical coupling and temperature-dependent polarization reversal in piezoelectric ceramics.

PubMed

Weaver, Paul M; Cain, Markys G; Correia, Tatiana M; Stewart, Mark

2011-09-01

Electrostriction plays a central role in describing the electromechanical properties of ferroelectric materials, including widely used piezoelectric ceramics. The piezoelectric properties are closely related to the underlying electrostriction. Small-field piezoelectric properties can be described as electrostriction offset by the remanent polarization which characterizes the ferroelectric state. Indeed, even large-field piezoelectric effects are accurately accounted for by quadratic electrostriction. However, the electromechanical properties deviate from this simple electrostrictive description at electric fields near the coercive field. This is particularly important for actuator applications, for which very high electromechanical coupling can be obtained in this region. This paper presents the results of an experimental study of electromechanical coupling in piezoelectric ceramics at electric field strengths close to the coercive field, and the effects of temperature on electromechanical processes during polarization reversal. The roles of intrinsic ferroelectric strain coupling and extrinsic domain processes and their temperature dependence in determining the electromechanical response are discussed.

Method And Apparatus For Two Dimensional Surface Property Analysis Based On Boundary Measurement

DOEpatents

Richardson, John G.

2005-11-15

An apparatus and method for determining properties of a conductive film is disclosed. A plurality of probe locations selected around a periphery of the conductive film define a plurality of measurement lines between each probe location and all other probe locations. Electrical resistance may be measured along each of the measurement lines. A lumped parameter model may be developed based on the measured values of electrical resistance. The lumped parameter model may be used to estimate resistivity at one or more selected locations encompassed by the plurality of probe locations. The resistivity may be extrapolated to other physical properties if the conductive film includes a correlation between resistivity and the other physical properties. A profile of the conductive film may be developed by determining resistivity at a plurality of locations. The conductive film may be applied to a structure such that resistivity may be estimated and profiled for the structure's surface.

Properties of the moon and its environment from lunar magnetometer measurements

NASA Technical Reports Server (NTRS)

Parkin, C. W.

1976-01-01

Lunar analysis of data from a total of nine lunar magnetometers is described. Results obtained concerning electromagnetic, compositional, and structural properties of the lunar interior are discussed. Specific topics covered include: lunar magnetic permeability and iron abundance; limits on a highly conducting lunar core; lunar electrical conductivity; and internal structure inferred from conductivity and permeability results.

Making better scar: Emerging approaches for modifying mechanical and electrical properties following infarction and ablation.

PubMed

Holmes, Jeffrey W; Laksman, Zachary; Gepstein, Lior

2016-01-01

Following myocardial infarction (MI), damaged myocytes are replaced by collagenous scar tissue, which serves an important mechanical function - maintaining integrity of the heart wall against enormous mechanical forces - but also disrupts electrical function as structural and electrical remodeling in the infarct and borderzone predispose to re-entry and ventricular tachycardia. Novel emerging regenerative approaches aim to replace this scar tissue with viable myocytes. Yet an alternative strategy of therapeutically modifying selected scar properties may also prove important, and in some cases may offer similar benefits with lower risk or regulatory complexity. Here, we review potential goals for such modifications as well as recent proof-of-concept studies employing specific modifications, including gene therapy to locally increase conduction velocity or prolong the refractory period in and around the infarct scar, and modification of scar anisotropy to improve regional mechanics and pump function. Another advantage of scar modification techniques is that they have applications well beyond MI. In particular, ablation treats electrical abnormalities of the heart by intentionally generating scar to block aberrant conduction pathways. Yet in diseases such as atrial fibrillation (AF) where ablation can be extensive, treating the electrical disorder can significantly impair mechanical function. Creating smaller, denser scars that more effectively block conduction, and choosing the location of those lesions by balancing their electrical and mechanical impacts, could significantly improve outcomes for AF patients. We review some recent advances in this area, including the use of computational models to predict the mechanical effects of specific lesion sets and gene therapy for functional ablation. Overall, emerging techniques for modifying scar properties represents a potentially important set of tools for improving patient outcomes across a range of heart diseases, whether used in place of or as an adjunct to regenerative approaches. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrically conductive poly-ɛ-caprolactone/polyethylene glycol/multi-wall carbon nanotube nanocomposite scaffolds coated with fibrin glue for myocardial tissue engineering

NASA Astrophysics Data System (ADS)

Mehdikhani, Mehdi; Ghaziof, Sharareh

2018-01-01

In this research, poly-ɛ-caprolactone (PCL), polyethylene glycol (PEG), multi-wall carbon nanotubes (MWCNTs), and nanocomposite scaffolds containing 0.5 and 1% (w/w) MWCNTs coated with fibrin glue (FG) were prepared via solvent casting and freeze-drying technique for cardiac tissue engineering. Scanning electron microscopy, transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction were used to characterize the samples. Furthermore, mechanical properties, electrical conductivity, degradation, contact angle, and cytotoxicity of the samples were evaluated. Results showed the uniform distribution of the MWCNTs with some aggregates in the prepared nanocomposite scaffolds. The scaffolds containing 1% (w/w) MWCNTs with and without FG coating illustrated optimum modulus of elasticity, high electrical conductivity, and wettability compared with PCL/PEG and PCL/PEG/0.5%(w/w) MWCNTs' scaffolds. FG coating enhanced electrical conductivity and cell response, and increased wettability of the constructs. The prepared scaffolds were degraded significantly after 60 days of immersion in PBS. Meanwhile, the nanocomposite containing 1% (w/w) MWCNTs with FG coating (S3) showed proper spreading and viability of the myoblasts seeded on it after 1, 4, and 7 days of culture. The scaffold containing 1% (w/w) MWCNTs with FG coating demonstrated optimal properties including acceptable mechanical properties, proper wettability, high electrical conductivity, satisfactory degradation, and excellent myoblasts response to it.

Examination of rapid phase change in copper wires to improve material models and understanding of burst

NASA Astrophysics Data System (ADS)

Olles, Joseph; Garasi, Christopher; Ball, J. Patrick

2017-11-01

Electrically-pulsed wires undergo multiple phase changes including a postulated metastable phase resulting in explosive wire growth. Simulations using the MHD approximation attempt to account for the governing physics, but lack the material properties (equations-of-state and electrical conductivity) to accurately predict the phase evolution of the exploding (bursting) wire. To explore the dynamics of an exploding copper wire (in water), we employ a digital micro-Schlieren streak photography technique. This imaging quantifies wire expansion and shock waves emitted from the wire during phase changes. Using differential voltage probes, a Rogowski coil, and timing fiducials, the phase change of the wire is aligned with electrical power and energy deposition. Time-correlated electrical diagnostics and imaging allow for detailed validation of MHD simulations, comparing observed phases with phase change details found in the material property descriptions. In addition to streak imaging, a long exposure image is taken to capture axial striations along the length of the wire. These images are used to compare with results from 3D MHD simulations which propose that these perturbations impact the rate of wire expansion and temporal change in phases. If successful, the experimental data will identify areas for improvement in the material property models, and modeling results will provide insight into the details of phase change in the wire with correlation to variations in the electrical signals.

Minimal models of electric potential oscillations in non-excitable membranes.

PubMed

Perdomo, Guillermo; Hernández, Julio A

2010-01-01

Sustained oscillations in the membrane potential have been observed in a variety of cellular and subcellular systems, including several types of non-excitable cells and mitochondria. For the plasma membrane, these electrical oscillations have frequently been related to oscillations in intracellular calcium. For the inner mitochondrial membrane, in several cases the electrical oscillations have been attributed to modifications in calcium dynamics. As an alternative, some authors have suggested that the sustained oscillations in the mitochondrial membrane potential induced by some metabolic intermediates depends on the direct effect of internal protons on proton conductance. Most theoretical models developed to interpret oscillations in the membrane potential integrate several transport and biochemical processes. Here we evaluate whether three simple dynamic models may constitute plausible representations of electric oscillations in non-excitable membranes. The basic mechanism considered in the derivation of the models is based upon evidence obtained by Hattori et al. for mitochondria and assumes that an ionic species (i.e., the proton) is transported via passive and active transport systems between an external and an internal compartment and that the ion affects the kinetic properties of transport by feedback regulation. The membrane potential is incorporated via its effects on kinetic properties. The dynamic properties of two of the models enable us to conclude that they may represent alternatives enabling description of the generation of electrical oscillations in membranes that depend on the transport of a single ionic species.

Transparent and Electrically Conductive Carbon Nanotube-Polymer Nanocomposite Materials for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Dervishi, E.; Biris, A. S.; Biris, A. R.; Lupu, D.; Trigwell, S.; Miller, D. W.; Schmitt, T.; Buzatu, D. A.; Wilkes, J. G.

2006-01-01

In recent years, nanocomposite materials have been extensively studied because of their superior electrical, magnetic, and optical properties and large number of possible applications that range from nano-electronics, specialty coatings, electromagnetic shielding, and drug delivery. The aim of the present work is to study the electrical and optical properties of carbon nanotube(CNT)-polymer nanocomposite materials for electrostatic charge dissipation. Single and multi-wall carbon nanotubes were grown by catalytic chemical vapor deposition (CCVD) on metal/metal oxide catalytic systems using acetylene or other hydrocarbon feedstocks. After the purification process, in which amorphous carbon and non-carbon impurities were removed, the nanotubes were functionalized with carboxylic acid groups in order to achieve a good dispersion in water and various other solvents. The carbon nanostructures were analyzed, both before and after functionalization by several analytical techniques, including microscopy, Raman spectroscopy, and X-Ray photoelectron spectroscopy. Solvent dispersed nanotubes were mixed (1 to 7 wt %) into acrylic polymers by sonication and allowed to dry into 25 micron thick films. The electrical and optical properties of the films were analyzed as a function of the nanotubes' concentration. A reduction in electrical resistivity, up to six orders of magnitude, was measured as the nanotubes' concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.

Electrical properties of binary mixtures of amino silicone oil and methyl iso butyl ketone

NASA Astrophysics Data System (ADS)

Shah, K. N.; Rana, V. A.; Vankar, H. P.

2018-05-01

The real and imaginary parts of the dielectric function of the binary mixtures of the methyl iso butyl ketone and amino silicone oil in the frequency range 100 Hz to 2 MHz were measured using precision LCR meter at 305.15 K. The electrical properties such as electrical modulus M*(ω), electrical conductivity σ*(ω) and complex impedance Z*(ω) were calculated using the dielectric function ɛ*(ω). The ionic polarization relaxation time (Τσ) and D.C. conductivity (σdc) were also calculated using electrical properties. The ionic behavior of methyl iso butyl ketone and non-ionic behavior of amino silicone oil are also explained. The electrical parameters are used to gain information about the effect of concentration variation of components of the mixtures on the electrical properties.

Tuning the gas sensing performance of single PEDOT nanowire devices.

PubMed

Hangarter, Carlos M; Hernandez, Sandra C; He, Xueing; Chartuprayoon, Nicha; Choa, Yong Ho; Myung, Nosang V

2011-06-07

This paper reports the synthesis and dopant dependent electrical and sensing properties of single poly(ethylenedioxythiophene) (PEDOT) nanowire sensors. Dopant type (i.e. polystyrenesulfonate (PSS(-)) and perchlorate (ClO(4)(-))) and solvent (i.e. acetonitrile and 1 : 1 water-acetonitrile mixture) were adjusted to change the conjugation length and hydrophilicity of nanowires which resulted in change of the electrical properties and sensing performance. Temperature dependent coefficient of resistance (TCR) indicated that the electrical properties are greatly dependent on dopants and electrolyte where greater disorder was found in PSS(-) doped PEDOT nanowires compared to ClO(4)(-) doped nanowires. Upon exposure to different analytes including water vapor and volatile organic compounds, these nanowire devices displayed substantially different sensing characteristics. ClO(4)(-) doped PEDOT nanowires from an acetonitrile bath show superior sensing responses toward less electronegative analytes and followed a power law dependence on the analyte concentration at high partial pressures. These tunable sensing properties were attributed to variation in the conjugation lengths, dopant type and concentration of the wires which may be attributed to two distinct sensing mechanisms: swelling within the bulk of the nanowire and work function modulation of Schottky barrier junction between nanowire and electrodes.

Effect of sputtering power on crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO transparent conducting thin films for optoelectronic devices

NASA Astrophysics Data System (ADS)

Hu, Yu Min; Li, Jung Yu; Chen, Nai Yun; Chen, Chih Yu; Han, Tai Chun; Yu, Chin Chung

2017-02-01

The crystallinity and intrinsic defects of transparent conducting oxide (TCO) films have a high impact on their optical and electrical properties and therefore on the performance of devices incorporating such films, including flat panel displays, electro-optical devices, and solar cells. The optical and electrical properties of TCO films can be modified by tailoring their deposition parameters, which makes proper understanding of these parameters crucial. Magnetron sputtering is the most adaptable method for preparing TCO films used in industrial applications. In this study, we investigate the direct and inter-property correlation effects of sputtering power (PW) on the crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO (AZO) TCO films. All of the films were preferentially c-axis-oriented with a wurtzite structure and had an average transmittance of over 80% in the visible wavelength region. Scanning electron microscopy images revealed significantly increased AZO film grain sizes for PW ≥ 150 W, which may lead to increased conductivity, carrier concentration, and optical band gaps but decreased carrier mobility and in-plane compressive stress in AZO films. Photoluminescence results showed that, with increasing PW, the near band edge emission gradually dominates the defect-related emissions in which zinc interstitial (Zni), oxygen vacancy (VO), and oxygen interstitial (Oi) are possibly responsible for emissions at 3.08, 2.8, and 2.0 eV, respectively. The presence of Zni- and Oi-related emissions at PW ≥ 150 W indicates a slight increase in the presence of Al atoms substituted at Zn sites (AlZn). The presence of Oi at PW ≥ 150 W was also confirmed by X-ray photoelectron spectroscopy results. These results clearly show that the crystallinity and intrinsic-defect type of AZO films, which dominate their optical and electrical properties, may be controlled by PW. This understanding may facilitate the development of TCO-based optoelectronic devices for industrial production.

Conductometry of electrolyte solutions

NASA Astrophysics Data System (ADS)

Safonova, Lyubov P.; Kolker, Arkadii M.

1992-09-01

A review is given of the theories of the electrical conductance of electrolyte solutions of different ionic strengths and concentrations, and of the models of ion association. An analysis is made of the methods for mathematical processing of experimental conductometric data. An account is provided of various theories describing the dependence of the limiting value of the ionic electrical conductance on the properties of the solute and solvent. The bibliography includes 115 references.

The challenges of achieving good electrical and mechanical properties when making structural supercapacitors

NASA Astrophysics Data System (ADS)

Ciocanel, C.; Browder, C.; Simpson, C.; Colburn, R.

2013-04-01

The paper presents results associated with the electro-mechanical characterization of a composite material with power storage capability, identified throughout the paper as a structural supercapacitor. The structural supercapacitor uses electrodes made of carbon fiber weave, a separator made of Celgard 3501, and a solid PEG-based polymer blend electrolyte. To be a viable structural supercapacitor, the material has to have good mechanical and power storage/electrical properties. The literature in this area is inconsistent on which electrical properties are evaluated, and how those properties are assessed. In general, measurements of capacitance or specific capacitance (i.e. capacitance per unit area or per unit volume) are made, without considering other properties such as leakage resistance and equivalent series resistance of the supercapacitor. This paper highlights the significance of these additional electrical properties, discusses the fluctuation of capacitance over time, and proposes methods to improve the stability of the material's electric properties over time.

Simultaneous Observation of Hybrid States for Cyber-Physical Systems: A Case Study of Electric Vehicle Powertrain.

PubMed

Lv, Chen; Liu, Yahui; Hu, Xiaosong; Guo, Hongyan; Cao, Dongpu; Wang, Fei-Yue

2017-08-22

As a typical cyber-physical system (CPS), electrified vehicle becomes a hot research topic due to its high efficiency and low emissions. In order to develop advanced electric powertrains, accurate estimations of the unmeasurable hybrid states, including discrete backlash nonlinearity and continuous half-shaft torque, are of great importance. In this paper, a novel estimation algorithm for simultaneously identifying the backlash position and half-shaft torque of an electric powertrain is proposed using a hybrid system approach. System models, including the electric powertrain and vehicle dynamics models, are established considering the drivetrain backlash and flexibility, and also calibrated and validated using vehicle road testing data. Based on the developed system models, the powertrain behavior is represented using hybrid automata according to the piecewise affine property of the backlash dynamics. A hybrid-state observer, which is comprised of a discrete-state observer and a continuous-state observer, is designed for the simultaneous estimation of the backlash position and half-shaft torque. In order to guarantee the stability and reachability, the convergence property of the proposed observer is investigated. The proposed observer are validated under highly dynamical transitions of vehicle states. The validation results demonstrates the feasibility and effectiveness of the proposed hybrid-state observer.

Determination of electrical properties of degraded mixed ionic conductors: Impedance studies with applied dc voltage

NASA Astrophysics Data System (ADS)

Bayer, T. J. M.; Carter, J. J.; Wang, Jian-Jun; Klein, Andreas; Chen, Long-Qing; Randall, C. A.

2017-12-01

Under electrical bias, mixed ionic conductors such as SrTiO3 are characterized by oxygen vacancy migration which leads to resistance degradation. The defect chemistry to describe the relationship between conductivity and oxygen vacancies is usually obtained by high temperature conductivity data or quenching experiments. These techniques can investigate the equilibrated state only. Here, we introduce a new approach using in-situ impedance studies with applied dc voltage to analyze the temperature dependent electrical properties of degraded SrTiO3 single crystals. This procedure is most beneficial since it includes electric field driven effects. The benefits of the approach are highlighted by comparing acceptor doped and undoped SrTiO3. This approach allows the determination of the temperature activation of both anodic and cathodic conductivity of Fe-doped SrTiO3 in the degraded state. The anodic activation energy matches well with the published results, while the activation energy of the degraded cathode region reported here is not in agreement with earlier assumptions. The specific discrepancies of the experimental data and the published defect chemistry are discussed, and a defect chemistry model that includes the strong temperature dependence of the electron conductivity in the cathode region is proposed.

Single-Molecule Electronics: Chemical and Analytical Perspectives.

PubMed

Nichols, Richard J; Higgins, Simon J

2015-01-01

It is now possible to measure the electrical properties of single molecules using a variety of techniques including scanning probe microcopies and mechanically controlled break junctions. Such measurements can be made across a wide range of environments including ambient conditions, organic liquids, ionic liquids, aqueous solutions, electrolytes, and ultra high vacuum. This has given new insights into charge transport across molecule electrical junctions, and these experimental methods have been complemented with increasingly sophisticated theory. This article reviews progress in single-molecule electronics from a chemical perspective and discusses topics such as the molecule-surface coupling in electrical junctions, chemical control, and supramolecular interactions in junctions and gating charge transport. The article concludes with an outlook regarding chemical analysis based on single-molecule conductance.

Energy Management and the Infrastructure System.

ERIC Educational Resources Information Center

Blackburn, James M.

1998-01-01

Describes a state-of-the-art energy management program at Wake Forest University (North Carolina) designed to include all on-campus property, and explores the various aspects of cost/benefit analysis in its development. A campus profile, electrical and thermal energy analyses, and a summary table of utility budget data are included. (GR)

An analysis of electrical conductivity model in saturated porous media

NASA Astrophysics Data System (ADS)

Cai, J.; Wei, W.; Qin, X.; Hu, X.

2017-12-01

Electrical conductivity of saturated porous media has numerous applications in many fields. In recent years, the number of theoretical methods to model electrical conductivity of complex porous media has dramatically increased. Nevertheless, the process of modeling the spatial conductivity distributed function continues to present challenges when these models used in reservoirs, particularly in porous media with strongly heterogeneous pore-space distributions. Many experiments show a more complex distribution of electrical conductivity data than the predictions derived from the experiential model. Studies have observed anomalously-high electrical conductivity of some low-porosity (tight) formations compared to more- porous reservoir rocks, which indicates current flow in porous media is complex and difficult to predict. Moreover, the change of electrical conductivity depends not only on the pore volume fraction but also on several geometric properties of the more extensive pore network, including pore interconnection and tortuosity. In our understanding of electrical conductivity models in porous media, we study the applicability of several well-known methods/theories to electrical characteristics of porous rocks as a function of pore volume, tortuosity and interconnection, to estimate electrical conductivity based on the micro-geometrical properties of rocks. We analyze the state of the art of scientific knowledge and practice for modeling porous structural systems, with the purpose of identifying current limitations and defining a blueprint for future modeling advances. We compare conceptual descriptions of electrical current flow processes in pore space considering several distinct modeling approaches. Approaches to obtaining more reasonable electrical conductivity models are discussed. Experiments suggest more complex relationships between electrical conductivity and porosity than experiential models, particularly in low-porosity formations. However, the available theoretical models combined with simulations do provide insight to how microscale physics affects macroscale electrical conductivity in porous media.

Scanning evanescent electro-magnetic microscope

DOEpatents

Xiang, Xiao-Dong; Gao, Chen; Schultz, Peter G.; Wei, Tao

2003-01-01

A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

Scanning evanescent electro-magnetic microscope

DOEpatents

Xiang, Xiao-Dong; Gao, Chen

2001-01-01

A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

The effect of silver (Ag) addition to mechanical and electrical properties of copper alloy (Cu) casting product

NASA Astrophysics Data System (ADS)

Felicia, Dian M.; Rochiem, R.; Laia, Standley M.

2018-04-01

Copper have good mechanical properties and good electrical conductivities. Therefore, copper usually used as electrical components. Silver have better electrical conductivities than copper. Female contact resistor is one of the electrical component used in circuit breaker. This study aims to analyze the effect of silver addition to hardness, strength, and electric conductivity properties of copper alloy. This study uses variation of 0; 0.035; 0.07; 0.1 wt. % Ag (silver) addition to determine the effect on mechanical properties and electrical properties of copper alloy through sand casting process. Modelling of thermal analysis and structural analysis was calculated to find the best design for the sand casting experiments. The result of Cu-Ag alloy as cast will be characterized by OES test, metallography test, Brinell hardness test, tensile test, and LCR meter test. The result of this study showed that the addition of silver increase mechanical properties of Cu-Ag. The maximum hardness value of this alloy is 83.1 HRB which is Cu-0.01 Ag and the lowest is 52.26 HRB which is pure Cu. The maximum strength value is 153.2 MPa which is Cu-0.07 Ag and the lowest is 94.6 MPa which is pure Cu. Silver addition decrease electrical properties of this alloy. The highest electric conductivity is 438.98 S/m which is pure Cu and the lowest is 52.61 S.m which is Cu-0.1 Ag.

Shell-binary nanoparticle materials with variable electrical and electro-mechanical properties.

PubMed

Zhang, P; Bousack, H; Dai, Y; Offenhäusser, A; Mayer, D

2018-01-18

Nanoparticle (NP) materials with the capability to adjust their electrical and electro-mechanical properties facilitate applications in strain sensing technology. Traditional NP materials based on single component NPs lack a systematic and effective means of tuning their electrical and electro-mechanical properties. Here, we report on a new type of shell-binary NP material fabricated by self-assembly with either homogeneous or heterogeneous arrangements of NPs. Variable electrical and electro-mechanical properties were obtained for both materials. We show that the electrical and electro-mechanical properties of these shell-binary NP materials are highly tunable and strongly affected by the NP species as well as their corresponding volume fraction ratio. The conductivity and the gauge factor of these shell-binary NP materials can be altered by about five and two orders of magnitude, respectively. These shell-binary NP materials with different arrangements of NPs also demonstrate different volume fraction dependent electro-mechanical properties. The shell-binary NP materials with a heterogeneous arrangement of NPs exhibit a peaking of the sensitivity at medium mixing ratios, which arises from the aggregation induced local strain enhancement. Studies on the electron transport regimes and micro-morphologies of these shell-binary NP materials revealed the different mechanisms accounting for the variable electrical and electro-mechanical properties. A model based on effective medium theory is used to describe the electrical and electro-mechanical properties of such shell-binary nanomaterials and shows an excellent match with experiment data. These shell-binary NP materials possess great potential applications in high-performance strain sensing technology due to their variable electrical and electro-mechanical properties.

Targeted Nanoparticles for Kidney Cancer Therapy

DTIC Science & Technology

2014-12-01

non modes in MWCNTs indicates that these structures also are exceptional heat conductors . The thermal conductivity of a single MWCNT along its...properties including extraordinary strength, unique electrical properties, and a specific heat and thermal conductivity that are among the highest...nanostructures, focusing on exposure to NIR. SWCNTs. Measurements of bulk samples of SWNTs indi- cate a room-temperature thermal conductivity over

Catalysts as sensors--a promising novel approach in automotive exhaust gas aftertreatment.

PubMed

Moos, Ralf

2010-01-01

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NO(x) traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NO(x)-loading of lean NO(x) traps, and the soot loading of Diesel particulate filters.

Electrical and chemical properties of XeCl*(308 nm) exciplex lamp created by a dielectric barrier discharge

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

Baadj, S.; Harrache, Z., E-mail: zharrache@yahoo.com; Belasri, A.

2013-12-15

The aim of this work is to highlight, through numerical modeling, the chemical and the electrical characteristics of xenon chloride mixture in XeCl* (308 nm) excimer lamp created by a dielectric barrier discharge. A temporal model, based on the Xe/Cl{sub 2} mixture chemistry, the circuit and the Boltzmann equations, is constructed. The effects of operating voltage, Cl{sub 2} percentage in the Xe/Cl{sub 2} gas mixture, dielectric capacitance, as well as gas pressure on the 308-nm photon generation, under typical experimental operating conditions, have been investigated and discussed. The importance of charged and excited species, including the major electronic and ionicmore » processes, is also demonstrated. The present calculations show clearly that the model predicts the optimal operating conditions and describes the electrical and chemical properties of the XeCl* exciplex lamp.« less

Catalysts as Sensors—A Promising Novel Approach in Automotive Exhaust Gas Aftertreatment

PubMed Central

Moos, Ralf

2010-01-01

Sensors that detect directly and in situ the status of automotive exhaust gas catalysts by monitoring the electrical properties of the catalyst coating itself are overviewed. Examples included in this review are the in-situ determination of the electrical impedance of three-way catalysts based on ceria-zirconia solutions and of lean NOx traps of earth-alkaline based coatings, as well as approaches to determine the ammonia loading in Fe-SCR-zeolites with electrical ac measurements. Even more sophisticated approaches based on interactions with electromagnetic waves are also reviewed. For that purpose, metallic stick-like antennas are inserted into the exhaust pipe. The catalyst properties are measured in a contactless manner, directly indicating the catalyst status. The radio frequency probes gauge the oxygen loading degree of three-way catalysts, the NOx-loading of lean NOx traps, and the soot loading of Diesel particulate filters. PMID:22163575

Electronic properties and optical absorption of a phosphorene quantum dot

NASA Astrophysics Data System (ADS)

Liang, F. X.; Ren, Y. H.; Zhang, X. D.; Jiang, Z. T.

2018-03-01

Using the tight-binding Hamiltonian approach, we theoretically study the electronic and optical properties of a triangular phosphorene quantum dot (PQD) including one normal zigzag edge and two skewed armchair edges (ZAA-PQD). It is shown that the energy spectrum can be classified into the filled band (FB), the zero-energy band (ZB), and the unfilled band (UB). Numerical calculations of the FB, ZB, and UB probability distributions show that the FB and the UB correspond to the bulk states, while the ZB corresponds to the edge states, which appear on all of the three edges of the ZAA-PQD sharply different from the other PQDs. We also find that the strains and the electric fields can affect the energy levels inhomogeneously. Then the optical properties of the ZAA-PQD are investigated. There appear some strong low-energy optical absorption peaks indicating its sensitive low-energy optical response that is absent in other PQDs. Moreover, the strains and the electric fields can make inhomogeneous influences on the optical spectrum of the ZAA-PQD. This work may provide a useful reference for designing the electrical, mechanical, and optical PQD devices.

Selected physical properties of various diesel blends

NASA Astrophysics Data System (ADS)

Hlaváčová, Zuzana; Božiková, Monika; Hlaváč, Peter; Regrut, Tomáš; Ardonová, Veronika

2018-01-01

The quality determination of biofuels requires identifying the chemical and physical parameters. The key physical parameters are rheological, thermal and electrical properties. In our study, we investigated samples of diesel blends with rape-seed methyl esters content in the range from 3 to 100%. In these, we measured basic thermophysical properties, including thermal conductivity and thermal diffusivity, using two different transient methods - the hot-wire method and the dynamic plane source. Every thermophysical parameter was measured 100 times using both methods for all samples. Dynamic viscosity was measured during the heating process under the temperature range 20-80°C. A digital rotational viscometer (Brookfield DV 2T) was used for dynamic viscosity detection. Electrical conductivity was measured using digital conductivity meter (Model 1152) in a temperature range from -5 to 30°C. The highest values of thermal parameters were reached in the diesel sample with the highest biofuel content. The dynamic viscosity of samples increased with higher concentration of bio-component rapeseed methyl esters. The electrical conductivity of blends also increased with rapeseed methyl esters content.

The efficiency of the use of composite materials in electrotechnical equipment

NASA Astrophysics Data System (ADS)

Kim, K.; Ivanov, S.

2018-02-01

The indicators of the efficiency of electrical installations are directly connected with the creating and using of new composite materials with the desired performance properties. The practical application of composite materials is one of the perspective scientific and technical directions, providing the increase of the efficiency of electrical installations due to the sealing of current parts by protecting them from the external medium. The technical characteristics of the composite material match to its structure and depend on the properties of the individual components. The verification of the compliance of material parameters is implemented by the methods of the computer analysis of a model of composite material in the form of the structure in which the individual elements have thermodynamic properties of the corresponding phase state. In the study the topology of individual elements in the material structure is defined by the conditional boundaries of the section within the studied composite. The efficiency of using the composite materials includes the raising of electrical safety, increasing the durability, reducing the costs of maintenance and repair and the extension of the scope of installations.

Application of the finite-field coupled-cluster method to calculate molecular properties relevant to electron electric-dipole-moment searches

NASA Astrophysics Data System (ADS)

Abe, M.; Prasannaa, V. S.; Das, B. P.

2018-03-01

Heavy polar diatomic molecules are currently among the most promising probes of fundamental physics. Constraining the electric dipole moment of the electron (e EDM ), in order to explore physics beyond the standard model, requires a synergy of molecular experiment and theory. Recent advances in experiment in this field have motivated us to implement a finite-field coupled-cluster (FFCC) approach. This work has distinct advantages over the theoretical methods that we had used earlier in the analysis of e EDM searches. We used relativistic FFCC to calculate molecular properties of interest to e EDM experiments, that is, the effective electric field (Eeff) and the permanent electric dipole moment (PDM). We theoretically determine these quantities for the alkaline-earth monofluorides (AEMs), the mercury monohalides (Hg X ), and PbF. The latter two systems, as well as BaF from the AEMs, are of interest to e EDM searches. We also report the calculation of the properties using a relativistic finite-field coupled-cluster approach with single, double, and partial triples' excitations, which is considered to be the gold standard of electronic structure calculations. We also present a detailed error estimate, including errors that stem from our choice of basis sets, and higher-order correlation effects.

Biosensing with Förster Resonance Energy Transfer Coupling between Fluorophores and Nanocarbon Allotropes

PubMed Central

Ding, Shaowei; Cargill, Allison A.; Das, Suprem R.; Medintz, Igor L.; Claussen, Jonathan C.

2015-01-01

Nanocarbon allotropes (NCAs), including zero-dimensional carbon dots (CDs), one-dimensional carbon nanotubes (CNTs) and two-dimensional graphene, exhibit exceptional material properties, such as unique electrical/thermal conductivity, biocompatibility and high quenching efficiency, that make them well suited for both electrical/electrochemical and optical sensors/biosensors alike. In particular, these material properties have been exploited to significantly enhance the transduction of biorecognition events in fluorescence-based biosensing involving Förster resonant energy transfer (FRET). This review analyzes current advances in sensors and biosensors that utilize graphene, CNTs or CDs as the platform in optical sensors and biosensors. Widely utilized synthesis/fabrication techniques, intrinsic material properties and current research examples of such nanocarbon, FRET-based sensors/biosensors are illustrated. The future outlook and challenges for the research field are also detailed. PMID:26110411

Vapor-phase polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) on commercial carbon coated aluminum foil as enhanced electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Tong, Linyue; Skorenko, Kenneth H.; Faucett, Austin C.; Boyer, Steven M.; Liu, Jian; Mativetsky, Jeffrey M.; Bernier, William E.; Jones, Wayne E.

2015-11-01

Laminar composite electrodes are prepared for application in supercapacitors using a catalyzed vapor-phase polymerization (VPP) of 3,4-ethylenedioxythiophene (EDOT) on the surface of commercial carbon coated aluminum foil. These highly electrically conducting polymer films provide for rapid and stable power storage per gram at room temperature. The chemical composition, surface morphology and electrical properties are characterized by Raman spectroscopy, scanning electron microscopy (SEM), and conducting atomic force microscopy (C-AFM). A series of electrical measurements including cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy are also used to evaluate electrical performance. The processing temperature of VPP shows a significant effect on PEDOT morphology, the degree of orientation and its electrical properties. The relatively high temperature leads to high specific area and large conductive domains of PEDOT layer which benefits the capacitive behavior greatly according to the data presented. Since the substrate is already highly conductive, the PEDOT based composite can be used as electrode materials directly without adding current collector. By this simple and efficient process, PEDOT based composites exhibit specific capacitance up to 134 F g-1 with the polymerization temperature of 110 °C.

Electrical contacts to individual SWCNTs: A review

PubMed Central

Hierold, Christofer; Haluska, Miroslav

2014-01-01

Summary Owing to their superior electrical characteristics, nanometer dimensions and definable lengths, single-walled carbon nanotubes (SWCNTs) are considered as one of the most promising materials for various types of nanodevices. Additionally, they can be used as either passive or active elements. To be integrated into circuitry or devices, they are typically connected with metal leads to provide electrical contacts. The properties and quality of these electrical contacts are important for the function and performance of SWCNT-based devices. Since carbon nanotubes are quasi-one-dimensional structures, contacts to them are different from those for bulk semiconductors. Additionally, some techniques used in Si-based technology are not compatible with SWCNT-based device fabrication, such as the contact area cleaning technique. In this review, an overview of the investigations of metal–SWCNT contacts is presented, including the principle of charge carrier injection through the metal–SWCNT contacts and experimental achievements. The methods for characterizing the electrical contacts are discussed as well. The parameters which influence the contact properties are summarized, mainly focusing on the contact geometry, metal type and the cleanliness of the SWCNT surface affected by the fabrication processes. Moreover, the challenges for widespread application of CNFETs are additionally discussed. PMID:25551048

DNA in the material world: electrical properties and nano-applications.

PubMed

Triberis, Georgios P; Dimakogianni, Margarita

2009-01-01

Contradictory experimental findings and theoretical interpretations have spurred intense debate over the electrical properties of the DNA double helix. In the present review article the various factors responsible for these divergences are discussed. The enlightenment of this issue could improve long range chemistry of oxidative DNA damage and repair processes, monitoring protein-DNA interactions and possible applications in nano-electronic circuit technology. The update experimental situation concerning measurements of the electrical conductivity is given. The character of the carriers responsible for the electrical conductivity measured in DNA is investigated. A theoretical model for the temperature dependence of the electrical conductivity of DNA is presented, based on microscopic models and percolation theoretical arguments. The theoretical results, excluding or including correlation effects, are applied to recent experimental findings for DNA, considering it as a one dimensional molecular wire. The results indicate that correlation effects are probably responsible for large hopping distances in DNA samples. Other theoretical conductivity models proposed for the interpretation of the responsible transport mechanism are also reviewed. Some of the most known and pioneering works on DNA's nano-applications, future developments and perspectives along with current technological limitations and patents are presented and discussed.

Solar cell array design handbook, volume 1

NASA Technical Reports Server (NTRS)

Rauschenbach, H. S.

1976-01-01

Twelve chapters discuss the following: historical developments, the environment and its effects, solar cells, solar cell filters and covers, solar cell and other electrical interconnections, blocking and shunt diodes, substrates and deployment mechanisms, material properties, design synthesis and optimization, design analysis, procurement, production and cost aspects, evaluation and test, orbital performance, and illustrative design examples. A comprehensive index permits rapid locating of desired topics. The handbook consists of two volumes: Volume 1 is of an expository nature while Volume 2 contains detailed design data in an appendix-like fashion. Volume 2 includes solar cell performance data, applicable unit conversion factors and physical constants, and mechanical, electrical, thermal optical, magnetic, and outgassing material properties. Extensive references are provided.

Engineering electrical properties of graphene: chemical approaches

NASA Astrophysics Data System (ADS)

Kim, Yong-Jin; Kim, Yuna; Novoselov, Konstantin; Hong, Byung Hee

2015-12-01

To ensure the high performance of graphene-based devices, it is necessary to engineer the electrical properties of graphene with enhanced conductivity, controlled work function, opened or closed bandgaps, etc. This can be performed by various non-covalent chemical approaches, including molecular adsorption, substrate-induced doping, polymerization on graphene, deposition of metallic thin films or nanoparticles, etc. In addition, covalent approaches such as the substitution of carbon atoms with boron or nitrogen and the functionalization with hydrogen or fluorine are useful to tune the bandgaps more efficiently, with better uniformity and stability. In this review, representative examples of chemically engineered graphene and its device applications will be reviewed, and remaining challenges will be discussed.

Friction, wear, and noise of slip ring and brush contacts for synchronous satellite use.

NASA Technical Reports Server (NTRS)

Lewis, N. E.; Cole, S. R.; Glossbrenner, E. W.; Vest, C. E.

1973-01-01

A program is being conducted for testing of slip rings for synchronous orbit application. Instrumentation systems necessary for monitoring electrical noise, friction, and brush wear at atmospheric pressure and at less than 50 nanotorr have been developed. A multiplex scheme necessary for the simultaneous recording of brush displacement, friction, and electrical noise has also been developed. Composite brushes consisting of silver-molybdenum disulfide-graphite and silver-niobium diselenide-graphite have been employed on rings of coin silver and rhodium plate. Brush property measurements made included measurement of density, electrical resistivity, shear strength, and microstructure.

Stephan Lany | NREL

Science.gov Websites

scientist with a background in electronic structure calculations for semiconducting materials. He joined Program. Research Interests His research interests include prediction of band-structure, optical , electrical, and transport properties from electronic structure theory; photovoltaic and thermoelectric

Graphene-based smart materials

NASA Astrophysics Data System (ADS)

Yu, Xiaowen; Cheng, Huhu; Zhang, Miao; Zhao, Yang; Qu, Liangti; Shi, Gaoquan

2017-09-01

The high specific surface area and the excellent mechanical, electrical, optical and thermal properties of graphene make it an attractive component for high-performance stimuli-responsive or 'smart' materials. Complementary to these inherent properties, functionalization or hybridization can substantially improve the performance of these materials. Typical graphene-based smart materials include mechanically exfoliated perfect graphene, chemical vapour deposited high-quality graphene, chemically modified graphene (for example, graphene oxide and reduced graphene oxide) and their macroscopic assemblies or composites. These materials are sensitive to a range of stimuli, including gas molecules or biomolecules, pH value, mechanical strain, electrical field, and thermal or optical excitation. In this Review, we outline different graphene-based smart materials and their potential applications in actuators, chemical or strain sensors, self-healing materials, photothermal therapy and controlled drug delivery. We also introduce the working mechanisms of graphene-based smart materials and discuss the challenges facing the realization of their practical applications.

Progress towards an electron electric dipole moment search in Europium-Barium Titanates

NASA Astrophysics Data System (ADS)

Eckel, Stephen; Sushkov, Alexander; Lamoreaux, Steven

2012-06-01

We report on recent progress on a search for the electron's electric dipole moment (eEDM) using solid- state Eu0.5Ba0.5TiO3. This material has many desirable properties including ferroelectricity below 200 K and paramagnetism above 1.8 K. When the sample has a non-zero electric polarization, the seven unpaired 4f electrons of the Eu^2+ ions in the lattice feel a large effective electric field of order 10 MV/cm in the direction of the polarization. This causes the electron spins to align with the electric polarization and generate a magnetization, which is measured using DC SQUID magnetometers. We will detail measurements of systematic effects along with recent results toward a measurement of the eEDM.

Novel Materials Containing Single-Wall Carbon Nanotubes Wrapped in Polymer Molecules

NASA Technical Reports Server (NTRS)

Smalley, Richard E.; O'Connell, Michael J.; Smith, Kenneth; Colbert, Daniel T.

2009-01-01

In this design, single-wall carbon nanotubes (SWNTs) have been coated in polymer molecules to create a new type of material that has low electrical conductivity, but still contains individual nanotubes, and small ropes of individual nanotubes, which are themselves good electrical conductors and serve as small conducting rods immersed in an electrically insulating matrix. The polymer is attached through weak chemical forces that are primarily non-covalent in nature, caused primarily through polarization rather than the sharing of valence electrons. Therefore, the electronic structure of the SWNT involved is substantially the same as that of free, individual (and small ropes of) SWNT. Their high conductivity makes the individual nanotubes extremely electrically polarizable, and materials containing these individual, highly polarizable molecules exhibit novel electrical properties including a high dielectric constant.

Thermoelectric properties of n-type polycrystalline BixSb2-xTe3 alloys

NASA Technical Reports Server (NTRS)

Snyder, J.; Gerovac, N.; Caillat, T.

2002-01-01

(BixSbl-x)2Te3(.5 = x = .7) polycrystalline samples were synthesized using a combination of melting and powder metallurgy techniques. The samples were hot pressed in graphite dies and cut perpendicular and parallel to the pressing direction. Samples were examined by microprobe analysis to determine their atomic composition. The thermoelectric properties were measured at room temperature in both directions. These properties include Seebeck coefficient, thermal conductivity, electrical resistivity, and Hall effect. The thermoelectric figure-of-merit, ZT, was calculated fiom these properties.

Effects of Radiation on Capacitor Dielectrics

NASA Technical Reports Server (NTRS)

Bouquet, F. L.; Somoano, R. B.; Frickland, P. O.

1987-01-01

Data gathered on key design parameters. Report discusses study of electrical and mechanical properties of irradiated polymer dielectric materials. Data compiled for use by designers of high-energy-density capacitors that operate in presence of ionizing radiation. Study focused on polycarbonates, polyetheretherketones, polymethylpentenes, polyimides (including polyetherimide), polyolefins, polysulfones (including polyethersulfone and polyphenylsulfone), and polyvinylidene fluorides.

An effective medium approach to modelling the pressure-dependent electrical properties of porous rocks

NASA Astrophysics Data System (ADS)

Han, Tongcheng

2018-07-01

Understanding the electrical properties of rocks under varying pressure is important for a variety of geophysical applications. This study proposes an approach to modelling the pressure-dependent electrical properties of porous rocks based on an effective medium model. The so-named Textural model uses the aspect ratios and pressure-dependent volume fractions of the pores and the aspect ratio and electrical conductivity of the matrix grains. The pores were represented by randomly oriented stiff and compliant spheroidal shapes with constant aspect ratios, and their pressure-dependent volume fractions were inverted from the measured variation of total porosity with differential pressure using a dual porosity model. The unknown constant stiff and compliant pore aspect ratios and the aspect ratio and electrical conductivity of the matrix grains were inverted by best fitting the modelled electrical formation factor to the measured data. Application of the approach to three sandstone samples covering a broad porosity range showed that the pressure-dependent electrical properties can be satisfactorily modelled by the proposed approach. The results demonstrate that the dual porosity concept is sufficient to explain the electrical properties of porous rocks under pressure through the effective medium model scheme.

A Preliminary Investigation of Hall Thruster Technology

NASA Technical Reports Server (NTRS)

Gallimore, Alec D.

1997-01-01

A three-year NASA/BMDO-sponsored experimental program to conduct performance and plume plasma property measurements on two Russian Stationary Plasma Thrusters (SPTs) has been completed. The program utilized experimental facilitates at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL). The main features of the proposed effort were as follows: (1) Characterized Hall thruster (and arcjet) performance by measuring ion exhaust velocity with probes at various thruster conditions; (2) Used a variety of probe diagnostics in the thruster plume to measure plasma properties and flow properties including T(sub e) and n(sub e) ion current density and ion energy distribution, and electric fields by mapping plasma potential; (3) Used emission spectroscopy to identify species within the plume and to measure electron temperatures. A key and unique feature of our research was our collaboration with Russian Hall thruster researcher Dr. Sergey A Khartov, Deputy Dean of International Relations at the Moscow Aviation Institute (MAI). His activities in this program included consulting on and participation in research at PEPL through use of a MAI-built SPT and ion energy probe.

Electrical properties of methane hydrate + sediment mixtures

USGS Publications Warehouse

Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven; Weitemeyer, Karen A.; Smith, Megan M; Roberts, Jeffery J.

2015-01-01

Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. Toward this goal, we built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EM field surveys. Here we report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. These results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.

Temperature-Dependent Dielectric Properties of Al/Epoxy Nanocomposites

NASA Astrophysics Data System (ADS)

Wang, Zijun; Zhou, Wenying; Sui, Xuezhen; Dong, Lina; Cai, Huiwu; Zuo, Jing; Chen, Qingguo

2016-06-01

Broadband dielectric spectroscopy was carried out to study the transition in electrical properties of Al/epoxy nanocomposites over the frequency range of 1-107 Hz and the temperature range of -20°C to 200°C. The dielectric permittivity, dissipation factor, and electrical conductivity of the nanocomposites increased with temperature and showed an abrupt increase around the glass transition temperature ( T g). The results clearly reveal an interesting transition of the electrical properties with increasing temperature: insulator below 70°C, conductor at about 70°C. The behavior of the transition in electrical properties of the nanocomposites was explored at different temperatures. The presence of relaxation peaks in the loss tangent and electric modulus spectra of the nanocomposites confirms that the chain segmental dynamics of the polymer is accompanied by the absorption of energy given to the system. It is suggested that the temperature-dependent transition of the electric properties in the nanocomposite is closely associated with the α-relaxation. The large increase in the dissipation factor and electric conductivity depends on the direct current conduction of thermally activated charge carriers resulting from the epoxy matrix above T g.

The Role of Electrical Anisotropy in Modeling and Interpreting Controlled-Source Electromagnetic Responses for Hydraulic Fracture Monitoring

NASA Astrophysics Data System (ADS)

Trevino, S., III; Hickey, M. S.; Everett, M. E.

2017-12-01

Controlled-Source Electromagnetics (CSEM) can be used to monitor the movement and extent of injection fluid during a hydraulic fracture. The response of the fluid to energization by a CSEM source is dependent upon the electrical conductivity difference between the fluid and background geological formation. An important property that must be taken into account when modeling and interpreting CSEM responses is that electrical conductivity may be anisotropic. We study the effect of electrical anisotropy in both the background formation and the fluid-injection zone. First, various properties of the background formation can affect anisotropy including variations in grain size, composition and bedding-plane orientation. In certain formations, such as shale, the horizontal component of the conductivity can be more than an order of magnitude larger than the vertical component. We study this effect by computing differences in surface CSEM responses using the analytic 1-D anisotropic primary solution of a horizontal electric dipole positioned at the surface. Second, during hydraulic fracturing, the injected fluid can create new fractures and infill existing natural fractures. To include the explicit fracture geometry in modeling, a large increase in the number of nodes and computational time is required which may not be feasible. An alternative is to instead model the large-scale fracture geometry as a uniform slab with an appropriate bulk conductivity. Micro-scale fracture geometry may cause preferential fluid propagation in a single direction or plane which can be represented by electrical anisotropy of the slab. To study such effects of bulk anisotropy on CSEM responses we present results from multiple scenarios of surface to surface hydraulic fracture monitoring using 3-D finite element modeling. The model uses Coulomb-gauged potentials to solve Maxwell's equations in the frequency domain and we have updated the code to allow a triaxial electrical conductivity tensor to be specified. By allowing for formation and target electrical anisotropy these modeling results contribute to a better understanding and faster interpretation of field data.

Trade-off between the Mechanical Strength and Microwave Electrical Properties of Functionalized and Irradiated Carbon Nanotube Sheets.

PubMed

Williams, Tiffany S; Orloff, Nathan D; Baker, James S; Miller, Sandi G; Natarajan, Bharath; Obrzut, Jan; McCorkle, Linda S; Lebron-Colón, Marisabel; Gaier, James; Meador, Michael A; Liddle, J Alexander

2016-04-13

Carbon nanotube (CNT) sheets represent a novel implementation of CNTs that enable the tailoring of electrical and mechanical properties for applications in the automotive and aerospace industries. Small molecule functionalization and postprocessing techniques, such as irradiation with high-energy particles, are methods that can enhance the mechanical properties of CNTs. However, the effect that these modifications have on the electrical conduction mechanisms has not been extensively explored. By characterizing the mechanical and electrical properties of multiwalled carbon nanotube (MWCNT) sheets with different functional groups and irradiation doses, we can expand our insights into the extent of the trade-off that exists between mechanical strength and electrical conductivity for commercially available CNT sheets. Such insights allow for the optimization of design pathways for engineering applications that require a balance of material property enhancements.

The effects of the conditions of char formation on the physical properties of charred phenolic-nylon

NASA Technical Reports Server (NTRS)

Smyly, E. D.; Pears, C. D.

1972-01-01

A study was made of the effects of the conditions of char formation on the physical properties of charred phenolic nylon of 0.577 gm/cu cm density. It was found that the thermal conductivity and several of the monitors correlate well with degradation conditions. The monitors included electrical resistivity, sonic velocity, porosity, lattice spacing and crystallite size.

Design principles of electrical synaptic plasticity.

PubMed

O'Brien, John

2017-09-08

Essentially all animals with nervous systems utilize electrical synapses as a core element of communication. Electrical synapses, formed by gap junctions between neurons, provide rapid, bidirectional communication that accomplishes tasks distinct from and complementary to chemical synapses. These include coordination of neuron activity, suppression of voltage noise, establishment of electrical pathways that define circuits, and modulation of high order network behavior. In keeping with the omnipresent demand to alter neural network function in order to respond to environmental cues and perform tasks, electrical synapses exhibit extensive plasticity. In some networks, this plasticity can have dramatic effects that completely remodel circuits or remove the influence of certain cell types from networks. Electrical synaptic plasticity occurs on three distinct time scales, ranging from milliseconds to days, with different mechanisms accounting for each. This essay highlights principles that dictate the properties of electrical coupling within networks and the plasticity of the electrical synapses, drawing examples extensively from retinal networks. Copyright © 2017 The Author. Published by Elsevier B.V. All rights reserved.

Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field.

PubMed

Ye, Hui; Steiger, Amanda

2015-08-12

In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural basis of cell-field interaction as well as the biological effects of electric stimulation.

General Theorems about Homogeneous Ellipsoidal Inclusions

ERIC Educational Resources Information Center

Korringa, J.; And Others

1978-01-01

Mathematical theorems about the properties of ellipsoids are developed. Included are Poisson's theorem concerning the magnetization of a homogeneous body of ellipsoidal shape, the polarization of a dielectric, the transport of heat or electricity through an ellipsoid, and other problems. (BB)

Cryogenic Properties of Inorganic Insulation Materials for ITER Magnets: A Review

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

Simon, N.J.

1994-12-01

Results of a literature search on the cryogenic properties of candidate inorganic insulators for the ITER TF magnets are reported. The materials investigated include: Al{sub 2}O{sub 3}, AlN, MgO, porcelain, SiO{sub 2}, MgAl{sub 2}O{sub 4}, ZrO{sub 2}, and mica. A graphical presentation is given of mechanical, elastic, electrical, and thermal properties between 4 and 300 K. A companion report reviews the low temperature irradiation resistance of these materials.

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

Walker, J.M.

The physical properties: mechanical, electrical, and thermal of a general purpose epoxy potting compound, filled with either glass microspheres, aluminum oxide or beta-eucryptite and catalyzed with either an aliphatic amine, a liquid aromatic amine eutectic blend, or a liquid anhydride are discussed. The properties of a CTBN modified epoxy are also included. Twelve formulation-cure cycle combinations were chosen for evaluation. The temperature dependent properties from -65/sup 0/ to 400/sup 0/F (-54/sup 0/ to 204/sup 0/C) for the 12 combinations are given.

Spatial Analysis of Slowly Oscillating Electric Activity in the Gut of Mice Using Low Impedance Arrayed Microelectrodes

PubMed Central

Taniguchi, Mizuki; Kajioka, Shunichi; Shozib, Habibul B.; Sawamura, Kenta; Nakayama, Shinsuke

2013-01-01

Smooth and elaborate gut motility is based on cellular cooperation, including smooth muscle, enteric neurons and special interstitial cells acting as pacemaker cells. Therefore, spatial characterization of electric activity in tissues containing these electric excitable cells is required for a precise understanding of gut motility. Furthermore, tools to evaluate spatial electric activity in a small area would be useful for the investigation of model animals. We thus employed a microelectrode array (MEA) system to simultaneously measure a set of 8×8 field potentials in a square area of ∼1 mm2. The size of each recording electrode was 50×50 µm2, however the surface area was increased by fixing platinum black particles. The impedance of microelectrode was sufficiently low to apply a high-pass filter of 0.1 Hz. Mapping of spectral power, and auto-correlation and cross-correlation parameters characterized the spatial properties of spontaneous electric activity in the ileum of wild-type (WT) and W/Wv mice, the latter serving as a model of impaired network of pacemaking interstitial cells. Namely, electric activities measured varied in both size and cooperativity in W/Wv mice, despite the small area. In the ileum of WT mice, procedures suppressing the excitability of smooth muscle and neurons altered the propagation of spontaneous electric activity, but had little change in the period of oscillations. In conclusion, MEA with low impedance electrodes enables to measure slowly oscillating electric activity, and is useful to evaluate both histological and functional changes in the spatio-temporal property of gut electric activity. PMID:24124480

Electrical excitability: a spectrum of properties in the progeny of a single embryonic neuroblast.

PubMed Central

Goodman, C S; Pearson, K G; Spitzer, N C

1980-01-01

We have examined the range of some properties of the progeny of a single embryonic precursor cell in the grasshopper. The approximately 100 progeny of this single neuroblast share certain features such as their transmitter and some aspects of their morphology; at the same time, however, they demonstrate a broad spectrum of electrical properties, from spiking to non-spiking neurons. The first-born progeny are spiking neurons with peripheral axons. Many of the progeny, including all of the last-born, do not generate action potentials. The nonspiking progeny are local intraganglionic neurons and appear to compose a major proportion of the progeny of this neuroblast. All of the nonspiking neurons have calcium inward current channels and can make action potentials when outward current channels are blocked. We propose a model for grasshopper neurogenesis based on cell lineage such that (i) certain features (e.g., transmitter) are shared by the progeny of all cell divisions from a single neuroblast, and (ii) other features (e.g., electrical properties) are shared by the progeny of a given birth position (e.g., first versus last born) from all of the neuroblasts. According to this model, the first-born progeny from all neuroblasts are spiking neurons, whereas the last-born are nonspiking. Images PMID:6246499

BiFeO3 Thin Films: A Playground for Exploring Electric-Field Control of Multifunctionalities

NASA Astrophysics Data System (ADS)

Yang, Jan-Chi; He, Qing; Yu, Pu; Chu, Ying-Hao

2015-07-01

A promising approach to the next generation of low-power, functional, and green nanoelectronics relies on advances in the electric-field control of lattice, charge, orbital, and spin degrees of freedom in novel materials. The possibility of electric-field control of these multiple materials functionalities offers interesting options across a range of modern technologies, including information communication, computing processes, data storage, active components, and functional electronics. This article reviews electric-field control and modulation of various degrees of freedom through the medium of multiferroic BiFeO3. Coexisting order parameters and inherent couplings in this materials system form a potent playground, enabling direct and indirect manipulation to obtain intriguing properties and functionalities with an electric stimulus. An in-depth understanding of those electrically controlled phenomena and breakthroughs is highlighted, paving a new route toward multifunctional nanoelectronics. This article concludes with a brief discussion on foreseeable challenges as well as future directions.

Nanotechnology Support for Memristor Nanoelectronics

DTIC Science & Technology

2012-03-01

hafnium oxide; 2) investigation of a conductive atomic force microscopy (cAFM) approach for measuring nanoparticle electrical properties , which was...films; and 4) successful measurement of memristive properties of nanoparticle -loaded insulating films. These results lay the groundwork for follow-on...a cAFM strategy for measuring nanoparticle electrical properties . Our initial approach to measuring nanoparticles was to attempt electrical

Scaling Effects in Perovskite Ferroelectrics: Fundamental Limits and Process-Structure-Property Relations

DOE PAGES

Ihlefeld, Jon F.; Harris, David T.; Keech, Ryan; ...

2016-07-05

Ferroelectric materials are well-suited for a variety of applications because they can offer a combination of high performance and scaled integration. Examples of note include piezoelectrics to transform between electrical and mechanical energies, capacitors used to store charge, electro-optic devices, and non-volatile memory storage. Accordingly, they are widely used as sensors, actuators, energy storage, and memory components, ultrasonic devices, and in consumer electronics products. Because these functional properties arise from a non-centrosymmetric crystal structure with spontaneous strain and a permanent electric dipole, the properties depend upon physical and electrical boundary conditions, and consequently, physical dimension. The change of properties withmore » decreasing physical dimension is commonly referred to as a size effect. In thin films, size effects are widely observed, while in bulk ceramics, changes in properties from the values of large-grained specimens is most notable in samples with grain sizes below several microns. It is important to note that ferroelectricity typically persists to length scales of about 10 nm, but below this point is often absent. Despite the stability of ferroelectricity for dimensions greater than ~10 nm, the dielectric and piezoelectric coefficients of scaled ferroelectrics are suppressed relative to their bulk counterparts, in some cases by changes up to 80%. The loss of extrinsic contributions (domain and phase boundary motion) to the electromechanical response accounts for much of this suppression. In this article the current understanding of the underlying mechanisms for this behavior in perovskite ferroelectrics are reviewed. We focus on the intrinsic limits of ferroelectric response, the roles of electrical and mechanical boundary conditions, grain size and thickness effects, and extraneous effects related to processing. Ultimately, in many cases, multiple mechanisms combine to produce the observed scaling effects.« less

Microstickies agglomeration by electric field.

PubMed

Du, Xiaotang Tony; Hsieh, Jeffery S

2016-01-01

Microstickies deposits on both paper machine and paper products when it agglomerates under step change in ionic strength, pH, temperature and chemical additives. These stickies increase the down time of the paper mill and decrease the quality of paper. The key property of microstickies is its smaller size, which leads to low removal efficiency and difficulties in measurement. Thus the increase of microstickies size help improve both removal efficiency and reduce measurement difficulty. In this paper, a new agglomeration technology based on electric field was investigated. The electric treatment could also increase the size of stickies particles by around 100 times. The synergetic effect between electric field treatment and detacky chemicals/dispersants, including polyvinyl alcohol, poly(diallylmethylammonium chloride) and lignosulfonate, was also studied.

Application of electrical stimulation for functional tissue engineering in vitro and in vivo

NASA Technical Reports Server (NTRS)

Park, Hyoungshin (Inventor); Freed, Lisa (Inventor); Vunjak-Novakovic, Gordana (Inventor); Langer, Robert (Inventor); Radisic, Milica (Inventor)

2013-01-01

The present invention provides new methods for the in vitro preparation of bioartificial tissue equivalents and their enhanced integration after implantation in vivo. These methods include submitting a tissue construct to a biomimetic electrical stimulation during cultivation in vitro to improve its structural and functional properties, and/or in vivo, after implantation of the construct, to enhance its integration with host tissue and increase cell survival and functionality. The inventive methods are particularly useful for the production of bioartificial equivalents and/or the repair and replacement of native tissues that contain electrically excitable cells and are subject to electrical stimulation in vivo, such as, for example, cardiac muscle tissue, striated skeletal muscle tissue, smooth muscle tissue, bone, vasculature, and nerve tissue.

Josephson junction in the quantum mesoscopic electric circuits with charge discreteness

NASA Astrophysics Data System (ADS)

Pahlavani, H.

2018-04-01

A quantum mesoscopic electrical LC-circuit with charge discreteness including a Josephson junction is considered and a nonlinear Hamiltonian that describing the dynamic of such circuit is introduced. The quantum dynamical behavior (persistent current probability) is studied in the charge and phase regimes by numerical solution approaches. The time evolution of charge and current, number-difference and the bosonic phase and also the energy spectrum of a quantum mesoscopic electric LC-circuit with charge discreteness that coupled with a Josephson junction device are investigated. We show the role of the coupling energy and the electrostatic Coulomb energy of the Josephson junction in description of the quantum behavior and the spectral properties of a quantum mesoscopic electrical LC-circuits with charge discreteness.

AC and DC electrical properties of graphene nanoplatelets reinforced epoxy syntactic foam

NASA Astrophysics Data System (ADS)

Zegeye, Ephraim; Wicker, Scott; Woldesenbet, Eyassu

2018-04-01

Benefits of employing graphene nanopletlates (GNPLs) in composite structures include mechanical as well as multifunctional properties. Understanding the impedance behavior of GNPLs reinforced syntactic foams may open new applications for syntactic foam composites. In this work, GNPLs reinforced syntactic foams were fabricated and tested for DC and AC electrical properties. Four sets of syntactic foam samples containing 0, 0.1, 0.3, and 0.5 vol% of GNPLs were fabricated and tested. Significant increase in conductivity of syntactic foams due to the addition of GNPLs was noted. AC impedance measurements indicated that the GNPLs syntactic foams become frequency dependent as the volume fraction of GNPLs increases. With addition of GNPLs, the characteristic of the syntactic foams are also observed to transition from dominant capacitive to dominant resistive behavior. This work was carried out at Southern University, Mechanical Engineering Department, Baton Rouge, LA 70802, United States of America.

Strain and Defect Engineering for Tailored Electrical Properties in Perovskite Oxide Thin Films and Superlattices

NASA Astrophysics Data System (ADS)

Hsing, Greg Hsiang-Chun

Functional complex-oxides display a wide spectrum of physical properties, including ferromagnetism, piezoelectricity, ferroelectricity, photocatalytic and metal-insulating transition (MIT) behavior. Within this family, oxides with a perovskite structure have been widely studied, especially in the form of thin films and superlattices (heterostructures), which are strategically and industrially important because they offer a wide range of opportunities for electronic, piezoelectric and sensor applications. The first part of my thesis focuses on understanding and tuning of the built-in electric field found in PbTiO3/SrTiO3 (PTO/STO) ferroelectric superlattices and other ferroelectric films. The artificial layering in ferroelectric superlattices is a potential source of polarization asymmetry, where one polarization state is preferred over another. One manifestation of this asymmetry is a built-in electric field associated with shifted polarization hysteresis. Using off-axis RF-magnetron sputtering, we prepared several compositions of PTO/STO superlattice thin films; and for comparison PbTiO3/SrRuO 3 (PTO/SRO) superlattices, which have an additional intrinsic compositional asymmetry at the interface. Both theoretical modeling and experiments indicate that the layer-by-layer superlattice structure aligns the Pb-O vacancy defect dipoles in the c direction which contributes significantly to the built-in electric field; however the preferred polarization direction is different between the PTO/STO and PTO/SRO interface. By designing a hybrid superlattice that combines PTO/STO and PTO/SRO superlattices, we show the built-in electric field can be tuned to zero by changing the composition of the combo-superlattice. The second part of my thesis focuses on the epitaxial growth of SrCrO 3 (SCO) films. The inconsistent reports regarding its electrical and magnetic properties through the years stem from the compositionally and structurally ill-defined polycrystalline samples, but still suggest strong coupling between structure and electronic structure of the material. Our goal is to establish the growth parameters necessary to achieve high-quality and single-phase epitaxial SCO films. Well-defined SCO films were deposited on different substrates to change the structural properties and epitaxial strain. Temperature-dependent resistivity measurements using the Van der Pauw method were performed to identify the metallicity of the films. The results showed a difference in the electrical properties of SCO films under different epitaxial strains.

Effect of CFRC layers on the electrical properties and failure mode of RC beams strengthened with CFRC composites

NASA Astrophysics Data System (ADS)

Wu, Sigang; Dai, Hongzhe; Wang, Wei

2007-12-01

This paper designs an innovative reinforced concrete (RC) beam strengthened with carbon fiber reinforced concrete (CFRC) composites. Six groups of test beams, five with different degrees of strengthening, achieved by changing the location and the thickness of the CFRC layer, and one virgin RC beam, were tested in four-point bending over a span of 3000 mm. We investigate the effect of the CFRC layer on the flexural performance and the electrical properties of the designed beams. The test results indicate that the CFRC strengthened RC beam exhibits improved electrical properties as well as better mechanical performance. Also, the location and the thickness of the CFRC layer affect the initial electrical resistance and other electrical properties of the beam. Relationships between electrical resistance, loading, deflection and cracks show that the increase in the electrical resistance can be used to monitor the extent of damage to the designed beam. Based on this discovery, a new health monitoring technique for RC structures is produced by means of electrical resistance measurements.

Analytical scanning evanescent microwave microscope and control stage

DOEpatents

Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

2013-01-22

A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

Analytical scanning evanescent microwave microscope and control stage

DOEpatents

Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

2009-06-23

A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

A systematic and feasible method for computing nuclear contributions to electrical properties of polyatomic molecules

NASA Astrophysics Data System (ADS)

Luis, Josep M.; Duran, Miquel; Andrés, José L.

1997-08-01

An analytic method to evaluate nuclear contributions to electrical properties of polyatomic molecules is presented. Such contributions control changes induced by an electric field on equilibrium geometry (nuclear relaxation contribution) and vibrational motion (vibrational contribution) of a molecular system. Expressions to compute the nuclear contributions have been derived from a power series expansion of the potential energy. These contributions to the electrical properties are given in terms of energy derivatives with respect to normal coordinates, electric field intensity or both. Only one calculation of such derivatives at the field-free equilibrium geometry is required. To show the useful efficiency of the analytical evaluation of electrical properties (the so-called AEEP method), results for calculations on water and pyridine at the SCF/TZ2P and the MP2/TZ2P levels of theory are reported. The results obtained are compared with previous theoretical calculations and with experimental values.

Energy storage in ferroelectric polymer nanocomposites filled with core-shell structured polymer@BaTiO3 nanoparticles: understanding the role of polymer shells in the interfacial regions.

PubMed

Zhu, Ming; Huang, Xingyi; Yang, Ke; Zhai, Xing; Zhang, Jun; He, Jinliang; Jiang, Pingkai

2014-11-26

The interfacial region plays a critical role in determining the electrical properties and energy storage density of dielectric polymer nanocomposites. However, we still know a little about the effects of electrical properties of the interfacial regions on the electrical properties and energy storage of dielectric polymer nanocomposites. In this work, three types of core-shell structured polymer@BaTiO3 nanoparticles with polymer shells having different electrical properties were used as fillers to prepare ferroelectric polymer nanocomposites. All the polymer@BaTiO3 nanoparticles were prepared by surface-initiated reversible-addition-fragmentation chain transfer (RAFT) polymerization, and the polymer shells were controlled to have the same thickness. The morphology, crystal structure, frequency-dependent dielectric properties, breakdown strength, leakage currents, energy storage capability, and energy storage efficiency of the polymer nanocomposites were investigated. On the other hand, the pure polymers having the same molecular structure as the shells of polymer@BaTiO3 nanoparticles were also prepared by RAFT polymerization, and their electrical properties were provided. Our results show that, to achieve nanocomposites with high discharged energy density, the core-shell nanoparticle filler should simultaneously have high dielectric constant and low electrical conductivity. On the other hand, the breakdown strength of the polymer@BaTiO3-based nanocomposites is highly affected by the electrical properties of the polymer shells. It is believed that the electrical conductivity of the polymer shells should be as low as possible to achieve nanocomposites with high breakdown strength.

Exceeding the filling fraction limit: An approach to enhancement of thermoelectric properties of filled - Co4Sb12 skutterudite

NASA Astrophysics Data System (ADS)

Graff, Jennifer Whitney

Currently the world energy usage has nearly tripled since 1950 and is projected to grow at a rate of 1.5% per year and predicted to at least double from the beginning of the millennium to 2050. The United States alone is currently consuming more energy than it can produce (≈ 97 Quadrillion BTU's consumed in 2011).(1) Presently, fossil fuels make up over 85% of our energy landscape, including both the stationary grid (like coal and nuclear power plants) and the mobile grid (automobiles using gas and oil). This presents a major demand for developing methods of saving, storing, and renewing energy. Answers to these existing energy demands must come from a variety of renewable sources including: solar, wind, biomass, geothermal and others. But currently, most renewable sources are only a small part of the big energy picture. One approach to this exponentially growing problem, lies within high efficiency (15%-20%) thermoelectric (TE) materials which address small, yet very important and specific, parts of a bigger problem. Specifically, Co4Sb12-based skutterudites, an increasingly favorable thermoelectric material for mid to high temperature applications (currently used in General Motors TE Generator devices). These materials have the ability to be 'tuned' or controlled thermally and electrically through doping and filling mechanisms, as you will see in this dissertation. However, one of the major drawbacks of TE materials is the difficulty in optimizing both electrical and thermal properties simultaneously. Typically, different control parameters are used in order to enhance the electrical and thermal properties individually. It is very rare to observe optimization of both in a TE material via one control parameter. However, the work presented herein successfully augments all TE properties, with one control variable, by using an approach that can be applied to all doped skutterudites and clathrate materials. Skutterudites are novel materials in that they are a binary system with a crystalline framework and a narrow band gap, so they naturally possess relatively good electrical properties. This dissertation seeks to answer the question: Can we continue to improve the efficiency of one of the leading TE materials in power generation applications -- skutterudites? In trying to answer this question we discovered a material that had never been tested for its TE properties and found that it exhibits behavior not typically observed in these materials as well as showing improvements in all TE properties (electrical and thermal) via one control parameter. We also successfully improved the TE efficiencies of several different filled skutterudites by a single approach which can be applied to other skutterudite and cage-like materials.

Impact of the interaction of material production and mechanical processing on the magnetic properties of non-oriented electrical steel

NASA Astrophysics Data System (ADS)

Leuning, Nora; Steentjes, Simon; Stöcker, Anett; Kawalla, Rudolf; Wei, Xuefei; Dierdorf, Jens; Hirt, Gerhard; Roggenbuck, Stefan; Korte-Kerzel, Sandra; Weiss, Hannes A.; Volk, Wolfram; Hameyer, Kay

2018-04-01

Thin laminations of non-grain oriented (NO) electrical steels form the magnetic core of rotating electrical machines. The magnetic properties of these laminations are therefore key elements for the efficiency of electric drives and need to be fully utilized. Ideally, high magnetization and low losses are realized over the entire polarization and frequency spectrum at reasonable production and processing costs. However, such an ideal material does not exist and thus, achievable magnetic properties need to be deduced from the respective application requirements. Parameters of the electrical steel such as lamination thickness, microstructure and texture affect the magnetic properties as well as their polarization and frequency dependence. These structural features represent possibilities to actively alter the magnetic properties, e.g., magnetization curve, magnetic loss or frequency dependence. This paper studies the influence of production and processing on the resulting magnetic properties of a 2.4 wt% Si electrical steel. Aim is to close the gap between production influence on the material properties and its resulting effect on the magnetization curves and losses at different frequencies with a strong focus on occurring interdependencies between production and mechanical processing. The material production is realized on an experimental processing route that comprises the steps of hot rolling, cold rolling, annealing and punching.

Peptide nanostructures in biomedical technology.

PubMed

Feyzizarnagh, Hamid; Yoon, Do-Young; Goltz, Mark; Kim, Dong-Shik

2016-09-01

Nanostructures of peptides have been investigated for biomedical applications due to their unique mechanical and electrical properties in addition to their excellent biocompatibility. Peptides may form fibrils, spheres and tubes in nanoscale depending on the formation conditions. These peptide nanostructures can be used in electrical, medical, dental, and environmental applications. Applications of these nanostructures include, but are not limited to, electronic devices, biosensing, medical imaging and diagnosis, drug delivery, tissue engineering and stem cell research. This review offers a discussion of basic synthesis methods, properties and application of these nanomaterials. The review concludes with recommendations and future directions for peptide nanostructures. WIREs Nanomed Nanobiotechnol 2016, 8:730-743. doi: 10.1002/wnan.1393 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

Structural, Transport and Electrochemical Properties of LiFePO4 Substituted in Lithium and Iron Sublattices (Al, Zr, W, Mn, Co and Ni)

PubMed Central

Molenda, Janina; Kulka, Andrzej; Milewska, Anna; Zając, Wojciech; Świerczek, Konrad

2013-01-01

LiFePO4 is considered to be one of the most promising cathode materials for lithium ion batteries for electric vehicle (EV) application. However, there are still a number of unsolved issues regarding the influence of Li and Fe-site substitution on the physicochemical properties of LiFePO4. This is a review-type article, presenting results of our group, related to the possibility of the chemical modification of phosphoolivine by introduction of cation dopants in Li and Fe sublattices. Along with a synthetic review of previous papers, a large number of new results are included. The possibility of substitution of Li+ by Al3+, Zr4+, W6+ and its influence on the physicochemical properties of LiFePO4 was investigated by means of XRD, SEM/EDS, electrical conductivity and Seebeck coefficient measurements. The range of solid solution formation in Li1−3xAlxFePO4, Li1−4xZrxFePO4 and Li1−6xWxFePO4 materials was found to be very narrow. Transport properties of the synthesized materials were found to be rather weakly dependent on the chemical composition. The battery performance of selected olivines was tested by cyclic voltammetry (CV). In the case of LiFe1−yMyPO4 (M = Mn, Co and Ni), solid solution formation was observed over a large range of y (0 < y ≤ 1). An increase of electrical conductivity for the substitution level y = 0.25 was observed. Electrons of 3d metals other than iron do not contribute to the electrical properties of LiFe1−yMyPO4, and substitution level y > 0.25 leads to considerably lower values of σ. The activated character of electrical conductivity with a rather weak temperature dependence of the Seebeck coefficient suggests a small polaron-type conduction mechanism. The electrochemical properties of LiFe1−yMyPO4 strongly depend on the Fe substitution level. PMID:28809235

Mechanical and electrical properties of low density polyethylene filled with carbon nanotubes

NASA Astrophysics Data System (ADS)

Sabet, Maziyar; Soleimani, Hassan

2014-08-01

Carbon nanotubes (CNTs) reveal outstanding electrical and mechanical properties in addition to nanometer scale diameter and high aspect ratio, consequently, making it an ideal reinforcing agent for high strength polymer composites. Low density polyethylene (LDPE)/CNT composites were prepared via melt compounding. Mechanical and electrical properties of (LDPE)/CNT composites with different CNT contents were studied in this research.

Effect of Fe-V nonstoichiometry on electrical and thermoelectric properties of Fe2VAl films

NASA Astrophysics Data System (ADS)

Kudo, Kohei; Yamada, Shinya; Chikada, Jinichiro; Shimanuki, Yuta; Nakamura, Yoshiaki; Hamaya, Kohei

2018-04-01

We study the effect of Fe-V nonstoichiometry on electrical and thermoelectric properties of Fe2VAl films. We find that temperature dependence of electrical resistivity and carrier type for Fe2- x V1+ x Al films are similar to those for bulk samples reported previously. In addition, the electrical and thermoelectric properties can be modulated by varying x. These results indicate that the electronic band structure having a pseudo gap at around the Fermi level is demonstrated even in thin-film Fe2VAl samples. This study will lead to further improvement in thermoelectric properties of the thin-film Fe2VAl.

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.

Experimental analysis of electrical properties of composite materials

NASA Astrophysics Data System (ADS)

Fiala, L.; Rovnaník, P.; Černý, R.

2017-02-01

Dry cement-based composites are electrically non-conductive materials that behave in electric field like dielectrics. However, a relatively low amount of electrically conductive admixture significantly increases the electrical conductivity which extends applicability of such materials in practice. Therefore, they can be used as self-monitoring sensors controlling development of cracks; as sensors monitoring moisture content or when treated by an external electrical voltage as heat sources used for deicing of material's surface layer. Alkali-activated aluminosilicates (AAA), as competing materials to cement-based materials, are intensively investigated in the present due to their superior durability and environmental impact. Whereas the electrical properties of AAA are similar to those cement-based, they can be enhanced in the same way. In both cases, it is crucial to find a reasonable amount of electrically conductive phase to design composites with a sufficient electrical conductivity at an affordable price. In this paper, electrical properties of composites based on AAA binder and electrically conductive admixture represented by carbon nanotubes (CNT) are investigated. Measurements of electrical properties are carried out by means of 2-probes DC technique on nine types of samples; reference sample without the conductive phase and samples with CNT admixture in amount of 0.1 % - 2.5 % by vol. A significant increase of the electrical conductivity starts from the amount of 0.5 % CNT admixture and in case of 2.5 % CNT is about three orders of magnitude higher compared to the reference sample.

Versatile apparatus for thermoelectric characterization of oxides at high temperatures

NASA Astrophysics Data System (ADS)

Schrade, Matthias; Fjeld, Harald; Norby, Truls; Finstad, Terje G.

2014-10-01

An apparatus for measuring the Seebeck coefficient and electrical conductivity is presented and characterized. The device can be used in a wide temperature range from room temperature to 1050 °C and in all common atmospheres, including oxidizing, reducing, humid, and inert. The apparatus is suitable for samples with different geometries (disk-, bar-shaped), allowing a complete thermoelectric characterization (including thermal conductivity) on a single sample. The Seebeck coefficient α can be measured in both sample directions (in-plane and cross-plane) simultaneously. Electrical conductivity is measured via the van der Pauw method. Perovskite-type CaMnO3 and the misfit cobalt oxide (Ca2CoO3)q(CoO2) are studied to demonstrate the temperature range and to investigate the variation of the electrical properties as a function of the measurement atmosphere.

Versatile apparatus for thermoelectric characterization of oxides at high temperatures.

PubMed

Schrade, Matthias; Fjeld, Harald; Norby, Truls; Finstad, Terje G

2014-10-01

An apparatus for measuring the Seebeck coefficient and electrical conductivity is presented and characterized. The device can be used in a wide temperature range from room temperature to 1050 °C and in all common atmospheres, including oxidizing, reducing, humid, and inert. The apparatus is suitable for samples with different geometries (disk-, bar-shaped), allowing a complete thermoelectric characterization (including thermal conductivity) on a single sample. The Seebeck coefficient α can be measured in both sample directions (in-plane and cross-plane) simultaneously. Electrical conductivity is measured via the van der Pauw method. Perovskite-type CaMnO3 and the misfit cobalt oxide (Ca2CoO3)q(CoO2) are studied to demonstrate the temperature range and to investigate the variation of the electrical properties as a function of the measurement atmosphere.

Discrete element weld model, phase 2

NASA Technical Reports Server (NTRS)

Prakash, C.; Samonds, M.; Singhal, A. K.

1987-01-01

A numerical method was developed for analyzing the tungsten inert gas (TIG) welding process. The phenomena being modeled include melting under the arc and the flow in the melt under the action of buoyancy, surface tension, and electromagnetic forces. The latter entails the calculation of the electric potential and the computation of electric current and magnetic field therefrom. Melting may occur at a single temperature or over a temperature range, and the electrical and thermal conductivities can be a function of temperature. Results of sample calculations are presented and discussed at length. A major research contribution has been the development of numerical methodology for the calculation of phase change problems in a fixed grid framework. The model has been implemented on CHAM's general purpose computer code PHOENICS. The inputs to the computer model include: geometric parameters, material properties, and weld process parameters.

Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics

NASA Astrophysics Data System (ADS)

Sainju, Deepak

Many modern optical and electronic devices, including photovoltaic devices, consist of multilayered thin film structures. Spectroscopic ellipsometry (SE) is a critically important characterization technique for such multilayers. SE can be applied to measure key parameters related to the structural, optical, and electrical properties of the components of multilayers with high accuracy and precision. One of the key advantages of this non-destructive technique is its capability of monitoring the growth dynamics of thin films in-situ and in real time with monolayer level precision. In this dissertation, the techniques of SE have been applied to study the component layer materials and structures used as back-reflectors and as the transparent contact layers in thin film photovoltaic technologies, including hydrogenated silicon (Si:H), copper indium-gallium diselenide (CIGS), and cadmium telluride (CdTe). The component layer materials, including silver and both intrinsic and doped zinc oxide, are fabricated on crystalline silicon and glass substrates using magnetron sputtering techniques. These thin films are measured in-situ and in real time as well as ex-situ by spectroscopic ellipsometry in order to extract parameters related to the structural properties, such as bulk layer thickness and surface roughness layer thickness and their time evolution, the latter information specific to real time measurements. The index of refraction and extinction coefficient or complex dielectric function of a single unknown layer can also be obtained from the measurement versus photon energy. Applying analytical expressions for these optical properties versus photon energy, parameters that describe electronic transport, such as electrical resistivity and electron scattering time, can be extracted. The SE technique is also performed as the sample is heated in order to derive the effects of annealing on the optical properties and derived electrical transport parameters, as well as the intrinsic temperature dependence of these properties and parameters. One of the major achievements of this dissertation research is the characterization of the thickness and optical properties of the interface layer formed between the silver and zinc oxide layers in a back-reflector structure used in thin film photovoltaics. An understanding of the impact of these thin film material properties on solar cell device performance has been complemented by applying reflectance and transmittance spectroscopy as well as simulations of cell performance.

Physical properties of hydrate‐bearing sediments

USGS Publications Warehouse

Waite, William F.; Santamarina, J.C.; Cortes, D.D.; Dugan, Brandon; Espinoza, D.N.; Germaine, J.; Jang, J.; Jung, J.W.; Kneafsey, T.J.; Shin, H.; Soga, K.; Winters, William J.; Yun, T.S.

2009-01-01

Methane gas hydrates, crystalline inclusion compounds formed from methane and water, are found in marine continental margin and permafrost sediments worldwide. This article reviews the current understanding of phenomena involved in gas hydrate formation and the physical properties of hydrate‐bearing sediments. Formation phenomena include pore‐scale habit, solubility, spatial variability, and host sediment aggregate properties. Physical properties include thermal properties, permeability, electrical conductivity and permittivity, small‐strain elastic P and S wave velocities, shear strength, and volume changes resulting from hydrate dissociation. The magnitudes and interdependencies of these properties are critically important for predicting and quantifying macroscale responses of hydrate‐bearing sediments to changes in mechanical, thermal, or chemical boundary conditions. These predictions are vital for mitigating borehole, local, and regional slope stability hazards; optimizing recovery techniques for extracting methane from hydrate‐bearing sediments or sequestering carbon dioxide in gas hydrate; and evaluating the role of gas hydrate in the global carbon cycle.

Visible light response, electrical transport, and amorphization in compressed organolead iodine perovskites.

PubMed

Ou, Tianji; Yan, Jiejuan; Xiao, Chuanhai; Shen, Wenshu; Liu, Cailong; Liu, Xizhe; Han, Yonghao; Ma, Yanzhang; Gao, Chunxiao

2016-06-02

Recent scientific advances on organic-inorganic hybrid perovskites are mainly focused on the improvement of power conversion efficiency. So far, how compression tunes their electronic and structural properties remains less understood. By combining in situ photocurrent, impedance spectroscopy, and X-ray diffraction (XRD) measurements, we have studied the electrical transport and structural properties of compressed CH3NH3PbI3 (MAPbI3) nanorods. The visible light response of MAPbI3 remains robust below 3 GPa while it is suppressed when it becomes amorphous. Pressure-induced electrical transport properties of MAPbI3 including resistance, relaxation frequency, and relative permittivity have been investigated under pressure up to 8.5 GPa by in situ impedance spectroscopy measurements. These results indicate that the discontinuous changes of these physical parameters occur around the structural phase transition pressure. The XRD studies of MAPbI3 under high pressure up to 20.9 GPa show that a phase transformation below 0.7 GPa, could be attributed to the tilting and distortion of PbI6 octahedra. And pressure-induced amorphization is reversible at a low density amorphous state but irreversible at a relatively higher density state. Furthermore, the MAPbI3 nanorods crush into nanopieces around 0.9 GPa which helps us to explain why the mixed phase of tetragonal and orthorhombic was observed at 0.5 GPa. The pressure modulated changes of electrical transport and visible light response properties open up a new approach for exploring CH3NH3PbI3-based photo-electronic applications.

Nonclassical Properties of Pulsed Second-Subharmonic Generation in Photonic-Band-Gap Structures

DTIC Science & Technology

2007-04-01

organized as follows. In Sec. II, a quan- tum model of the nonlinear interaction including both Heisenberg equations for operator electric-field ampli...can then be derived from the Heisenberg equations (for details, see [45, 46]; dX̂ dz = − i h̄ [ Ĝ, X̂ ] ; (13) considering the following momentum...disper- sion, we decompose the electric-field operator amplitudes Êa (a = p, s) using mode operator amplitudes âa in the Heisenberg picture [5, 8

Semiconductor neutron detector

DOEpatents

Ianakiev, Kiril D [Los Alamos, NM; Littlewood, Peter B [Cambridge, GB; Blagoev, Krastan B [Arlington, VA; Swinhoe, Martyn T [Los Alamos, NM; Smith, James L [Los Alamos, NM; Sullivan, Clair J [Los Alamos, NM; Alexandrov, Boian S [Los Alamos, NM; Lashley, Jason Charles [Santa Fe, NM

2011-03-08

A neutron detector has a compound of lithium in a single crystal form as a neutron sensor element. The lithium compound, containing improved charge transport properties, is either lithium niobate or lithium tantalate. The sensor element is in direct contact with a monitor that detects an electric current. A signal proportional to the electric current is produced and is calibrated to indicate the neutrons sensed. The neutron detector is particularly useful for detecting neutrons in a radiation environment. Such radiation environment may, e.g. include gamma radiation and noise.

Batteries for electric and hybrid-electric vehicles.

PubMed

Cairns, Elton J; Albertus, Paul

2010-01-01

Batteries have powered vehicles for more than a century, but recent advances, especially in lithium-ion (Li-ion) batteries, are bringing a new generation of electric-powered vehicles to the market. Key barriers to progress include system cost and lifetime, and derive from the difficulty of making a high-energy, high-power, and reversible electrochemical system. Indeed, although humans produce many mechanical and electrical systems, the number of reversible electrochemical systems is very limited. System costs may be brought down by using cathode materials less expensive than those presently employed (e.g., sulfur or air), but reversibility will remain a key challenge. Continued improvements in the ability to synthesize and characterize materials at desired length scales, as well as to use computations to predict new structures and their properties, are facilitating the development of a better understanding and improved systems. Battery research is a fascinating area for development as well as a key enabler for future technologies, including advanced transportation systems with minimal environmental impact.

Characterization of the electromechanical properties of EAP materials

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph; Sherrita, Stewart; Bhattachary, Kaushik; Lih, Shyh-Shiuh

2001-01-01

Electroactive polymers (EAP) are an emerging class of actuation materials. Their large electrically induced strains (longitudinal or bending), low density, mechanical flexibility, and ease of processing offer advantages over traditional electroactive materials. However, before the capability of these materials can be exploited, their electrical and mechanical behavior must be properly quantified. Two general types of EAP can be identified. The first type is ionic EAP, which requires relatively low voltages (<10V) to achieve large bending deflections. This class usually needs to be hydrated and electrochemical reactions may occur. The second type is Electronic-EAP and it involves electrostrictive and/or Maxwell stresses. This type of materials requires large electric fields (>100MV/m) to achieve longitudinal deformations at the range from 4 - 360%. Some of the difficulties in characterizing EAP include: nonlinear properties, large compliance (large mismatch with metal electrodes), nonhomogeneity resulting from processing, etc. To support the need for reliable data, the authors are developing characterization techniques to quantify the electroactive responses and material properties of EAP materials. The emphasis of the current study is on addressing electromechanical issues related to the ion-exchange type EAP also known as IPMC. The analysis, experiments and test results are discussed in this paper.

Atomistic study of the electronic contact resistivity between the half-Heusler alloys (HfCoSb, HfZrCoSb, HfZrNiSn) and the metal Ag

NASA Astrophysics Data System (ADS)

He, Yuping; Léonard, François; Spataru, Catalin D.

2018-06-01

Half-Heusler (HH) alloys have shown promising thermoelectric properties in the medium- and high-temperature range. To harness these material properties for thermoelectric applications, it is important to realize electrical contacts with low electrical contact resistivity. However, little is known about the detailed structural and electronic properties of such contacts and the expected values of contact resistivity. Here, we employ atomistic ab initio calculations to study electrical contacts in a subclass of HH alloys consisting of the compounds HfCoSb, HfZrCoSb, and HfZrNiSn. By using Ag as a prototypical metal, we show that the termination of the HH material critically determines the presence or absence of strong deformations at the interface. Our study includes contacts to doped materials, and the results indicate that the p -type materials generally form ohmic contacts while the n -type materials have a small Schottky barrier. We calculate the temperature dependence of the contact resistivity in the low- to medium-temperature range and provide quantitative values that set lower limits for these systems.

Influence of MBE growth modes and conditions on spontaneous formation of metallic In nanoparticles and electrical properties of InN matrix

NASA Astrophysics Data System (ADS)

Komissarova, T. A.; Wang, P.; Paturi, P.; Wang, X.; Ivanov, S. V.

2017-11-01

Influence of the molecular beam epitaxy (MBE) growth conditions on the electrical properties of the InN epilayers in terms of minimization of the effect of spontaneously formed In nanoparticles was studied. A three-step growth sequence was used, including direct MBE growth of an InN nucleation layer, migration enhanced epitaxy (MEE) of an InN buffer layer, and In-rich MBE growth of the main InN layer, utilizing the droplet elimination by radical-beam irradiation (DERI) technique. The three-step growth regime was found to lead to decreasing the relative amount of In nanoparticles to 4.8% and 3.8% in In-rich and near-stoichiometric conditions, respectively, whereas the transport properties are better for the In-rich growth. Further reduction of the metallic indium inclusions in the InN films, while keeping simultaneously satisfactory transport parameters, is hardly possible due to fundamental processes of InN thermal decomposition and formation of the nitrogen vacancy conglomerates in the InN matrix. The In inclusions are shown to dominate the electrical conductivity of the InN films even at their minimum amount.

Effect of Cr doping on the structural, morphological, optical and electrical properties of indium tin oxide films

NASA Astrophysics Data System (ADS)

Mirzaee, Majid; Dolati, Abolghasem

2015-03-01

We report on the preparation and characterization of high-purity chromium (0.5-2.5 at.%)-doped indium tin oxide (ITO, In:Sn = 90:10) films deposited by sol-gel-mediated dip coating. The effects of different Cr-doping contents on structural, morphological, optical and electrical properties of the films were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy and four-point probe methods. XRD showed high phase purity cubic In2O3 and indicated a contraction of the lattice with Cr doping. FESEM micrographs show that grain size decreased with increasing the Cr-doping content. A method to determine chromium species in the sample was developed through the decomposition of the Cr 2 p XPS spectrum in Cr6+ and Cr3+ standard spectra. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum sheet resistance of 4,300 Ω/Sq and an average optical transmittance of 85 % in the visible region with a band gap of 3.421 eV, were achieved for the films doped with Cr-doping content of 2 at.%.

Electricity from the Silk Cocoon Membrane

PubMed Central

Tulachan, Brindan; Meena, Sunil Kumar; Rai, Ratan Kumar; Mallick, Chandrakant; Kusurkar, Tejas Sanjeev; Teotia, Arun Kumar; Sethy, Niroj Kumar; Bhargava, Kalpana; Bhattacharya, Shantanu; Kumar, Ashok; Sharma, Raj Kishore; Sinha, Neeraj; Singh, Sushil Kumar; Das, Mainak

2014-01-01

Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management. PMID:24961354

Electricity from the silk cocoon membrane.

PubMed

Tulachan, Brindan; Meena, Sunil Kumar; Rai, Ratan Kumar; Mallick, Chandrakant; Kusurkar, Tejas Sanjeev; Teotia, Arun Kumar; Sethy, Niroj Kumar; Bhargava, Kalpana; Bhattacharya, Shantanu; Kumar, Ashok; Sharma, Raj Kishore; Sinha, Neeraj; Singh, Sushil Kumar; Das, Mainak

2014-06-25

Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management.

Electricity from the Silk Cocoon Membrane

NASA Astrophysics Data System (ADS)

Tulachan, Brindan; Meena, Sunil Kumar; Rai, Ratan Kumar; Mallick, Chandrakant; Kusurkar, Tejas Sanjeev; Teotia, Arun Kumar; Sethy, Niroj Kumar; Bhargava, Kalpana; Bhattacharya, Shantanu; Kumar, Ashok; Sharma, Raj Kishore; Sinha, Neeraj; Singh, Sushil Kumar; Das, Mainak

2014-06-01

Silk cocoon membrane (SCM) is an insect engineered structure. We studied the electrical properties of mulberry (Bombyx mori) and non-mulberry (Tussar, Antheraea mylitta) SCM. When dry, SCM behaves like an insulator. On absorbing moisture, it generates electrical current, which is modulated by temperature. The current flowing across the SCM is possibly ionic and protonic in nature. We exploited the electrical properties of SCM to develop simple energy harvesting devices, which could operate low power electronic systems. Based on our findings, we propose that the temperature and humidity dependent electrical properties of the SCM could find applications in battery technology, bio-sensor, humidity sensor, steam engines and waste heat management.

Metallic nanoislands on graphene: A metamaterial for chemical, mechanical, optical, and biological applications.

PubMed

Marin, Brandon C; Ramirez, Julian; Root, Samuel E; Aklile, Eden; Lipomi, Darren J

2017-01-01

Graphene decorated with metallic nanoparticles exhibits electronic, optical, and mechanical properties that neither the graphene nor the metal possess alone. These composite films have electrical conductivity and optical properties that can be modulated by a range of physical, chemical, and biological signals. Such properties are controlled by the morphology of the nanoisland films, which can be deposited on graphene using a variety of techniques, including in situ chemical synthesis and physical vapor deposition. These techniques produce non-random (though loosely defined) morphologies, but can be combined with lithography to generate deterministic patterns. Applications of these composite films include chemical sensing and catalysis, energy storage and transport (including photoconductivity), mechanical sensing (using a highly sensitive piezroresistive effect), optical sensing (including so-called "piezoplasmonic" effects), and cellular biophysics (i.e sensing the contractions of cardiomyocytes and myoblasts).

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.

Electrical properties of methane hydrate + sediment mixtures: The σ of CH 4 Hydrate + Sediment

DOE PAGES

Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven; ...

2015-07-30

Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. We built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EMmore » field surveys. We report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. Finally, these results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.« less

Design and analysis of a toroidal tester for the measurement of core losses under axial compressive stress

NASA Astrophysics Data System (ADS)

Alatawneh, Natheer; Rahman, Tanvir; Lowther, David A.; Chromik, Richard

2017-06-01

Electric machine cores are subjected to mechanical stresses due to manufacturing processes. These stresses include radial, circumferential and axial components that may have significant influences on the magnetic properties of the electrical steel and hence, on the output and efficiencies of electrical machines. Previously, most studies of iron losses due to mechanical stress have considered only radial and circumferential components. In this work, an improved toroidal tester has been designed and developed to measure the core losses and the magnetic properties of electrical steel under a compressive axial stress. The shape of the toroidal ring has been verified using 3D stress analysis. Also, 3D electromagnetic simulations show a uniform flux density distribution in the specimen with a variation of 0.03 T and a maximum average induction level of 1.5 T. The developed design has been prototyped, and measurements were carried out using a steel sample of grade 35WW300. Measurements show that applying small mechanical stresses normal to the sample thickness rises the delivered core losses, then the losses decrease continuously as the stress increases. However, the drop in core losses at high stresses does not go lower than the free-stress condition. Physical explanations for the observed trend of core losses as a function of stress are provided based on core loss separation to the hysteresis and eddy current loss components. The experimental results show that the effect of axial compressive stress on magnetic properties of electrical steel at high level of inductions becomes less pronounced.

Electrical properties of methane hydrate + sediment mixtures: The σ of CH 4 Hydrate + Sediment

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

Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven

Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. We built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EMmore » field surveys. We report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. Finally, these results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.« less

Nonmetallic materials handbook. Volume 2: Epoxy and silicone materials

NASA Technical Reports Server (NTRS)

Podlaseck, S. E.

1982-01-01

Chemical and physical property test data obtained during qualification and receiving inspection testing of nonmetallic materials for the Viking Mars Lander program is presented. Thermochemical data showing degradation as a function of temperature from room temperature through 773 K is included. These data include activation energies for thermal degradation, rate constants, and exo- and/or endotherms. Thermal degradations carried out under vacuum include mass spectral data taken simultaneously during the decomposition. Many materials have supporting data such as condensation rates of degassed products and isothermal weight loss. Changes in mechanical, electrical, and thermal properties after exposure to 408 K in nitrogen for times ranging from 380 to 570 hours are included for many materials.

Intracellular Physiology of the Rat Suprachiasmatic Nucleus: Electrical Properties, Neurotransmission, and Effects of Neuromodulators.

DTIC Science & Technology

1992-08-24

Rat Suprachiasmatic Nucleus: Electrical Properties, Neurotransmission, and Effects of Neuromodulators 12. PERSONAL AUTHOR(S) F. Edward Dudek 13a...intrinsic electrical properties, synaptic and non-synaptic transmission, and neuromodulation . We have studied the role of excitatory and inhibitory amino... Neuromodulation : Smithson. K.G.. MacVicar. B.A. and Hatton. G.I. (1983) The Biochemical Control of Neuronal Excitability. Oxford Polyethylene glycol

Spectroscopic and electric properties of the LiCs molecule: a coupled cluster study including higher excitations

NASA Astrophysics Data System (ADS)

Sørensen, L. K.; Fleig, T.; Olsen, J.

2009-08-01

Aimed at obtaining complete and highly accurate potential energy surfaces for molecules containing heavy elements, we present a new general-order coupled cluster method which can be applied in the framework of the spin-free Dirac formalism. As an initial application we present a systematic study of electron correlation and relativistic effects on the spectroscopic and electric properties of the LiCs molecule in its electronic ground state. In particular, we closely investigate the importance of excitations higher than coupled cluster doubles, spin-free and spin-dependent relativistic effects and the correlation of outer-core electrons on the equilibrium bond length, the harmonic vibrational frequency, the dissociation energy, the dipole moment and the static electric dipole polarizability. We demonstrate that our new implementation allows for highly accurate calculations not only in the bonding region but also along the complete potential curve. The quality of our results is demonstrated by a vibrational analysis where an almost complete set of vibrational levels has been calculated accurately.

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.

Preliminary Evaluation of Polyarylate Dielectric Films for Cryogenic Applications

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; Hammoud, Ahmad; Fialla, Peter

2002-01-01

Polymeric materials are used extensively on spacecraft and satellites in electrical power and distribution systems, as thermal blankets and optical surface coatings, as well as mechanical support structures. The reliability of these systems when exposed to the harsh environment of space is very critical to the success of the mission and the safety of the crew in manned-flight ventures. In this work, polyarylate films were evaluated for potential use as capacitor dielectrics and wiring insulation for cryogenic applications. Two grades of the film were characterized in terms of their electrical and mechanical properties before and after exposure to liquid nitrogen (-196 C). The electrical characterization consisted of capacitance and dielectric loss measure Cents in the frequency range of 50 Hz to 100 kHz, and volume and surface resistivities. The mechanical measurements performed included changes in tensile (Young's modulus, elongation-at-break, and tensile strength) and structural properties (dimensional change, weight, and surface morphology). The preliminary results, which indicate good stability of the polymer after exposure to liquid nitrogen, are presented and discussed.

Electrical Properties of Reactive Liquid Crystal Semiconductors

NASA Astrophysics Data System (ADS)

McCulloch, Iain; Coelle, Michael; Genevicius, Kristijonas; Hamilton, Rick; Heckmeier, Michael; Heeney, Martin; Kreouzis, Theo; Shkunov, Maxim; Zhang, Weimin

2008-01-01

Fabrication of display products by low cost printing technologies such as ink jet, gravure offset lithography and flexography requires solution processable semiconductors for the backplane electronics. The products will typically be of lower performance than polysilicon transistors, but comparable to amorphous silicon. A range of prototypes are under development, including rollable electrophoretic displays, active matrix liquid crystal displays (AMLCD's), and flexible organic light-emitting diode (OLED) displays. Organic semiconductors that offer both electrical performance and stability with respect to storage and operation under ambient conditions are required. This work describes the initial evaluation of reactive mesogen semiconductors, which can polymerise within mesophase temperatures, “freezing in” the order in crosslinked domains. These crosslinked domains offer mechanical stability and are inert to solvent exposure in further processing steps. Reactive mesogens containing conjugated aromatic cores, designed to facilitate charge transport and provide good oxidative stability, were prepared and their liquid crystalline properties evaluated. Both time-of-flight and field effect transistor devices were prepared and their electrical characterisation reported.

Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

DOEpatents

Ramirez, Abelardo L.; Cooper, John F.; Daily, William D.

1996-01-01

This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination.

Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

DOEpatents

Ramirez, A.L.; Cooper, J.F.; Daily, W.D.

1996-02-27

This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination. 1 fig.

Electrical properties of dislocations in III-Nitrides

NASA Astrophysics Data System (ADS)

Cavalcoli, D.; Minj, A.; Pandey, S.; Cavallini, A.

2014-02-01

Research on GaN, AlN, InN (III-N) and their alloys is achieving new heights due their high potential applications in photonics and electronics. III-N semiconductors are mostly grown epitaxially on sapphire, and due to the large lattice mismatch and the differences in the thermal expansion coefficients, the structures usually contain many threading dislocations (TDs). While their structural properties have been widely investigated, their electrical characteristics and their role in the transport properties of the devices are still debated. In the present contribution we will show conductive AFM studies of TDs in GaN and Al/In GaN ternary alloys to evidence the role of strain, different surface polarity and composition on their electrical properties. Local I-V curves measured at TDs allowed us to clarify their role in the macroscopic electrical properties (leakage current, mobilities) of III-N based devices. Samples obtained by different growers (AIXTRON, III-V Lab) were studied. The comparison between the results obtained in the different alloys allowed us to understand the role of In and Al on the TDs electrical properties.

Determination of consolidation properties using electrical resistivity

NASA Astrophysics Data System (ADS)

Kibria, Golam; Hossain, Sahadat; Khan, Mohammad Sadik

2018-05-01

Electrical conductivity is an indirect method used to evaluate pore-structures and their influence on macro and microscale behavior of soils. Although this method can provide useful information about the consolidation properties of soil samples, insufficient studies have been conducted to identify correlations between electrical and consolidation properties. The current study presents electrical resistivity responses of clayey samples at different consolidation stages. The consolidation properties of four soil specimens were measured in conjunction with electrical conductivity. Scanning electron microscope (SEM) analyses were performed on soil samples before and after consolidation to identify the changes in fabric morphology due to the application of loads. It was observed that the electrical conductivity of samples decreased with the increase of pressure, and the trends of variations were similar to e vs. logP curves. Although a linear correlation exists between electrical conductivity and void ratio, the relationship depends on the structural changes in clay particles. Therefore, changes in fabric structures were analyzed using SEM images, and results showed that the aspect ratio of the particles increased as much as 18.3% after consolidation. Based on the investigation, the coefficient of consolidations and one-dimensional strain were determined using electrical resistivity measurements.

The tunable mechanical property of water-filled carbon nanotubes under an electric field

NASA Astrophysics Data System (ADS)

Ye, Hongfei; Zhang, Zhongqiang; Zhang, Hongwu; Chen, Zhen; Zong, Zhi; Zheng, Yonggang

2014-03-01

The spring-induced compression of water-filled carbon nanotubes (CNTs) under an electric field is investigated by molecular dynamics simulations. Due to the incompressibility and polarity of water, the mechanical property of CNTs can be tuned through filling with water molecules and applying an electric field. To explore the variation of the mechanical property of water-filled CNTs, the effects of the CNT length, the filling density and the electric field intensity are examined. The simulation results indicate that the water filling and electric field can result in a slight change in the elastic property (the elastic modulus and Poisson's ratio) of water-filled CNTs. However, the yield stress and average post-buckling stress exhibit a significant response to the water density and electric field intensity. As compared to hollow CNTs, the increment in yield stress of the water-filled CNTs under an electric field of 2.0 V Å-1 is up to 35.29%, which is even higher than that resulting from metal filling. The findings from this study provide a valuable theoretical basis for designing and fabricating the controlling units at the nanoscale.

Electric currents in cosmic plasmas

NASA Technical Reports Server (NTRS)

Alfven, H.

1977-01-01

It is suggested that dualism is essential for the physics of cosmic plasmas, that is, that some phenomena should be described by a magnetic field formalism, and others by an electric current formalism. While in earlier work the magnetic field aspect has dominated, at present there is a systematic exploration of the particle (or current) aspect. A number of phenomena which can be understood only from the particle aspect are surveyed. Topics include the formation of electric double layers, the origin of 'explosive' events like magnetic substorms and solar flares, and the transfer of energy from one region to another. A method for exploring many of these phenomena is to draw the electric circuit in which the current flows and then study its properties. A number of simple circuits are analyzed in this way.

Effects of Combined Stressing on the Electrical Properties of Film and Ceramic Capacitors

NASA Technical Reports Server (NTRS)

Overton, Eric; Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.

1994-01-01

Advanced power systems which generate, control, and distribute electrical power to many large loads are a requirement for future space exploration missions. The development of high temperature insulating materials and power components constitute a key element in systems which are lightweight, efficient, and are capable of surviving the hostile space environment. In previous work, experiments were carried out to evaluate film and ceramic capacitors for potential use in high temperature applications. The effects of thermal stressing, in air and without electrical bias, on the electrical properties of the capacitors as a function of thermal aging up to 12 weeks were determined. In this work, the combined effects of thermal aging and electrical stresses on the properties of teflon film and ceramic power capacitors were examined. The ceramic capacitors were thermally aged for 35 weeks and the teflon capacitors for 15 weeks at 200 C under full electrical bias and were characterized, on a weekly basis, in terms of their capacitance stability and electrical loss in the frequency range of 50 Hz to 100 kHz. DC leakage current measurements were also obtained. The results obtained represent the influence that short-term thermal aging and electrical bias have on the electrical properties of the power capacitors characterized.

Characterization of dielectric properties of nanocellulose from wood and algae for electrical insulator applications.

PubMed

Le Bras, David; Strømme, Maria; Mihranyan, Albert

2015-05-07

Cellulose is one of the oldest electrically insulating materials used in oil-filled high-power transformers and cables. However, reports on the dielectric properties of nanocellulose for electrical insulator applications are scarce. The aim of this study was to characterize the dielectric properties of two nanocellulose types from wood, viz., nanofibrillated cellulose (NFC), and algae, viz., Cladophora cellulose, for electrical insulator applications. The cellulose materials were characterized with X-ray diffraction, nitrogen gas and moisture sorption isotherms, helium pycnometry, mechanical testing, and dielectric spectroscopy at various relative humidities. The algae nanocellulose sample was more crystalline and had a lower moisture sorption capacity at low and moderate relative humidities, compared to NFC. On the other hand, it was much more porous, which resulted in lower strength and higher dielectric loss than for NFC. It is concluded that the solid-state properties of nanocellulose may have a substantial impact on the dielectric properties of electrical insulator applications.

Effect of the microstructure on electrical properties of high-purity germanium

NASA Astrophysics Data System (ADS)

Podkopaev, O. I.; Shimanskii, A. F.; Molotkovskaya, N. O.; Kulakovskaya, T. V.

2013-05-01

The interrelation between the electrical properties and the microstructure of high-purity germanium crystals has been revealed. The electrical conductivity of polycrystalline samples increases and the life-time of nonequilibrium charge carriers in them decreases with a decrease in the crystallite sizes.

Fabrication and characterization of carbon nanotube turfs

NASA Astrophysics Data System (ADS)

Qiu, Anqi

Carbon nanotube turfs are vertically aligned, slightly tortuous and entangled functional nanomaterials that exhibit high thermal and electrical properties. CNT turfs exhibit unique combinations of thermal and electrical conductivity, energy absorbing capability, low density and adhesive behavior. The objective of this study is to fabricate, measure, manipulate and characterize CNT turfs and thus determine the relationship between a turf's properties and its morphology, and provide guidance for developing links between turf growth conditions and of the subsequent turf properties. Nanoindentation was utilized to determine the mechanical and in situ electrical properties of CNT turfs. Elastic properties do not vary significantly laterally within a single turf, quantifying for the first time the ability to treat the turf as a mechanical continuum throughout. The use of the average mechanical properties for any given turf should be suitable for design purpose without the necessity of accounting for lateral spatial variation in structure. Properties variation based on time dependency, rate dependency, adhesive behavior and energy absorption and dissipation behavior have been investigated for these CNT turfs. Electrical properties measurements of CNT turfs have been carried out and show that a constant electrical current at a constant penetration depth indicates that a constant number of CNTs in contact with the tip; combining with the results that adhesive load increased with an increasing penetration hold time, thus we conclude that during a hold period of nanoindentation, individual tubes increase their individual attachment to the tip. CNT turfs show decreased adhesion and modulus after exposure to an electron beam due to carbon deposition and subsequent oxidation. To increase the modulus of the turf, axial compression and solvent capillary were used to increase the density of the turf by up to 15 times. Structure-property relationships were determined from the density and tortuosity measurements carried out through in situ electrical measurements and directionality measurements. Increasing density increases the mechanical properties as well as electrical conductivity. The modulus increased with a lower tortuosity, which may be related to the compressive buckling positioning.

Electrical conduction in polymer dielectrics

NASA Technical Reports Server (NTRS)

Cotts, D. B.

1985-01-01

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

High-altitude electrical discharges associated with thunderstorms and lightning

NASA Astrophysics Data System (ADS)

Liu, Ningyu; McHarg, Matthew G.; Stenbaek-Nielsen, Hans C.

2015-12-01

The purpose of this paper is to introduce electrical discharge phenomena known as transient luminous events above thunderstorms to the lightning protection community. Transient luminous events include the upward electrical discharges from thunderstorms known as starters, jets, and gigantic jets, and electrical discharges initiated in the lower ionosphere such as sprites, halos, and elves. We give an overview of these phenomena with a focus on starters, jets, gigantic jets, and sprites, because similar to ordinary lightning, streamers and leaders are basic components of these four types of transient luminous events. We present a few recent observations to illustrate their main properties and briefly review the theories. The research in transient luminous events has not only advanced our understanding of the effects of thunderstorms and lightning in the middle and upper atmosphere, but also improved our knowledge of basic electrical discharge processes critical for sparks and lightning.

Systematics of the electric dipole response in stable tin isotopes

NASA Astrophysics Data System (ADS)

Bassauer, Sergej; von Neumann-Cosel, Peter; Tamii, Atsushi

2018-05-01

The electric dipole is an important property of heavy nuclei. Precise information on the electric dipole response provides information on the electric dipole polarisability which in turn allows to extract important constraints on neutron-skin thickness in heavy nuclei and parameters of the symmetry energy. The tin isotope chain is particularly suited for a systematic study of the dependence of the electric dipole response on neutron excess as it provides a wide mass range of accessible isotopes with little change of the underlying structure. Recently an inelastic proton scattering experiment under forward angles including 0º on 112,116,124Sn was performed at the Research Centre for Nuclear Physics (RCNP), Japan with a focus on the low-energy dipole strength and the polarisability. First results are presented here. Using data from an earlier proton scattering experiment on 120Sn the gamma strength function and level density are determined for this nucleus.

Nanocellulose as Material Building Block for Energy and Flexible Electronics

NASA Astrophysics Data System (ADS)

Hu, Liangbing

2014-03-01

In this talk, I will discuss the fabrications, properties and device applications of functional nanostructured paper based on nanocellulose. Nanostructures with tunable optical, electrical, ionic and mechanical properties will be discussed. Lab-scale demonstration devices, including low-cost Na-ion batteries, microbial fuel cells, solar cells, transparent transistors, actuators and touch screens will be briefly mentioned. These studies show that nanocellulose is a promising green material for electronics and energy devices.

Effect of mechanical and electrical stimuli in conductive atomic force microscopy with noble metal-coated tips

NASA Astrophysics Data System (ADS)

Zade, Vishal; Kang, Hung-Sen; Lee, Min Hwan

2018-01-01

Conductive atomic force microscopy has been widely employed to study the localized electrical properties of a wide range of substrates in non-vacuum conditions by the use of noble metal-coated tips. However, quantitative characterization of the electrical properties was often precluded by unpredictable changes in the tip apex morphology, and/or electronic transport characteristics of undesired oxide overcoats on the tip. In this paper, the impact of mechanical and electrical stimuli on the apex geometry of gold coated tips and electrical conduction properties at the tip-substrate contact is discussed by choosing gold and highly ordered pyrolytic graphite as the representative tip and substrate materials, respectively.

Effects of rutin on the physicochemical properties of skin fibroblasts membrane disruption following UV radiation.

PubMed

Dobrzyńska, Izabela; Gęgotek, Agnieszka; Gajko, Ewelina; Skrzydlewska, Elżbieta; Figaszewski, Zbigniew A

2018-02-25

Human skin provides the body's first line of defense against physical and environmental assaults. This study sought to determine how rutin affects the membrane electrical properties, sialic acid content, and lipid peroxidation levels of fibroblast membranes after disruption by ultraviolet (UV) radiation. Changes in cell function may affect the basal electrical surface properties of cell membranes, and changes can be detected by electrokinetic measurements. The charge density of the fibroblast membrane surface was measured as a function of pH. A four-component equilibrium model was used to describe the interaction between ions in solution and ions on the membrane surface. Agreement was found between experimental and theoretical charge variation curves of fibroblast cells between pH 2.5 and 8. Sialic acid content was determined by Svennerholm's resorcinol method, and lipid peroxidation was estimated by measuring the malondialdehyde level. Compared to untreated cells, ultraviolet A (UVA)- or ultraviolet B (UVB)-treated skin cell membranes exhibited higher concentrations of acidic functional groups and higher average association constants with hydroxyl ions, but lower average association constants with hydrogen ions. Moreover, our results showed that UVA and UVB radiation is associated with increased levels of sialic acid and lipid peroxidation products in fibroblasts. Rutin protected cells from some deleterious UV-associated membrane changes, including changes in electrical properties, oxidative state, and biological functions. Copyright © 2018 Elsevier B.V. All rights reserved.

An Adventure into Applied Mathematics with Fibonacci Numbers.

ERIC Educational Resources Information Center

Jean, Roger V.; Johnson, Marjorie

1989-01-01

Describes properties of Fibonacci numbers, including the law of recurrence and relationship with the Golden Ratio. Discussed are some applications of the numbers to sewage of towns on a river bank, resistances in electric circuits, and leafy stems in botany. Lists four references. (YP)

[Research on electricity frequency property of blood].

PubMed

Hu, Maoqing; Huang, Hua; Yuan, Zirun; Chen, Huaiqing; Den, Lihua

2006-02-01

On the basis of our previous work, the electric frequency property of human blood in different components, in physiological state and in pathological state (diabetes) are tested and analyzed in the range of 1Hz-20MHz progressively. Among the different components of blood; the lowest electrical impedance is serum; the plasma and the whole blood gradually become larger, the blood corpuscle is the largest one. Otherwise, the negative phase of serum is the largest, the plasma and the whole blood are lower, and the blood corpuscle is the lowest. Here, the question is why the effect of the electric capacity of serum and plasma is the biggest in the condition of no cell and cell membrane; diabetes mellitus is an endocrine disorder in which blood changes obviously, the electric frequency property of the blood of diabetic patients changes markedly; the electrical impedance of blood decreases (more obviously with low frequency), the negative phase increases (more obviously with high frequency). These indicate that the increase of electric conductivity in diabetic patients' blood is due to electric capacitance conductivity that is related to the changes of cell membrane, deformation abilities and aggregation of RBC. Related experiments demonstrate again that with the progressing of research in the electric frequency property of blood, we may use the theory and method of electricity to examine some important characters of blood in a different way, and so to corroborate other tests and analyses.

Surface electrical properties experiment. [for Taurus-Littrow region of the moon on Apollo 17

NASA Technical Reports Server (NTRS)

Simmons, G.

1974-01-01

The Surface Electrical Properties Experiment (SEP) was flown to the moon in December 1972 on Apollo 17 and used to explore a portion of the Taurus-Littrow region. SEP used a relatively new technique, termed radio frequency interferometry (RFI). Electromagnetic waves were radiated from two orthogonal, horizontal electric dipole antennas on the surface of the moon at frequencies of 1, 2, 4, 8, 16, and 32 Mhz. The field strength of the EM waves was measured as a function of distance with a receiver mounted on the Lunar Roving Vehicle and using three orthogonal, electrically small, loops. The interference pattern produced by the waves that travelled above the moon's surface and those that travelled below the surface was recorded on magnetic tape. The tape was returned to earth for analysis and interpretation. Several reprints, preprints, and an initial draft of the first publication of the SEP results are included. These documents provide a rather complete account of the details of the theory of the RFI technique, of the terrestrial tests of the technique, and of the present state of our interpretation of the Apollo 17 data.

Optimization and improvement of thermal energy harvesting by using pyroelectric materials

NASA Astrophysics Data System (ADS)

El Fatnani, Fatima Zahra; Guyomar, Daniel; Mazroui, M.'hammed; Belhora, Fouad; Boughaleb, Yahia

2016-06-01

We deal with the thermal energy which is one of the ambient energy sources surely exploitable, but it has not been much interest as the mechanical energy. In this paper, our aim is to use thermal energy and show that it's an important source for producing the electrical energy through pyroelectric effect which is the property of some dielectric materials to show a spontaneous electrical polarization versus temperature. In this context, we present a concept to harvest a thermal energy using infrared rays and pyroelectric effect. The pyroelectric material used in this work can generate an electrical voltage when it subjected to a temperature change which will be ensured by the use of infrared lamp. Our experimental results show that the electrical voltage, current and harvested power increased significantly when increasing the area of the pyroelectric element. The experimental results show also that with this simple concept we harvested a heavy amount value of power which will certainly be useful in an extensive range of applications, including sensors and infrared detection. These results shed light on the thermoelectric energy conversion by Ceramic lead zirconate titanate (PZT) buzzer having the pyroelectric property.

The mechanical stability of polyimide films at high pH

NASA Technical Reports Server (NTRS)

Croall, Catharine I.; St.clair, Terry L.

1990-01-01

Polyimide insulated electrical wire has been widely used in the aerospace industry in commercial, military, and to a lesser degree, general aviation aircraft since the early 1970s. Wiring failures linked to insulation damage have drawn much attention in the media and concerns have developed regarding the long term stability and safety of polyimide insulated electrical wire. The mechanical durability and chemical stability of polyimide insulated wire are affected by hydrolysis, notch propagation, wet and dry arc tracking, topcoat flaking, and degradation due to high pH fluids. Several polyimides were selected for evaluation for resistance to degradation by various aqueous alkaline solutions. The polyimides under evaluation include commercially available films such as KAPTON (tradename), APICAL (tradename), LARC-TPI, and UPILEX (tradename) R and S, as well as a number of experimental films prepared at NASA-Langley. Material properties investigated include viscosity, solubility, moisture absorption, glass transition temperature, dielectric constant, and mechanical properties before and after exposure to various conditions.

Nonlinear conductivity in silicon nitride

NASA Astrophysics Data System (ADS)

Tuncer, Enis

2017-08-01

To better comprehend electrical silicon-package interaction in high voltage applications requires full characterization of the electrical properties of dielectric materials employed in wafer and package level design. Not only the packaging but wafer level dielectrics, i.e. passivation layers, would experience high electric fields generated by the voltage applied pads. In addition the interface between the passivation layer and a mold compound might develop space charge because of the mismatch in electrical properties of the materials. In this contribution electrical properties of a thin silicon nitride (Si3N4) dielectric is reported as a function of temperature and electric field. The measured values later analyzed using different temperature dependent exponential expressions and found that the Mott variable range hopping conduction model was successful to express the data. A full temperature/electric field dependency of conductivity is generated. It was found that the conduction in Si3N4 could be expressed like a field ionization or Fowler-Nordheim mechanism.

Processing, electrical and microwave properties of sputtered Tl-Ca-Ba-Cu-O superconducting thin films

NASA Technical Reports Server (NTRS)

Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

1993-01-01

A reproducible fabrication process has been established for TlCaBaCuO thin films on LaAlO3 substrates by RF magnetron sputtering and post-deposition processing methods. Electrical transport properties of the thin films were measured on patterned four-probe test devices. Microwave properties of the films were obtained from unloaded Q measurements of all-superconducting ring resonators. This paper describes the processing, electrical and microwave properties of Tl2Ca1Ba2Cu2O(x) 2122-plane phase thin films.

Magnetic and electrical properties of Martian particles

NASA Technical Reports Server (NTRS)

Olhoeft, G. R.

1991-01-01

The only determinations of the magnetic properties of Martian materials come from experiments on the two Viking Landers. The results suggest Martian soil containing 1 to 10 percent of a highly magnetic phase. Though the magnetic phase mineral was not conclusively identified, the predominate interpretation is that the magnetic phase is probably maghemite. The electrical properties of the surface of Mars were only measured remotely by observations with Earth based radar, microwave radiometry, and inference from radio-occultation of Mars orbiting spacecraft. No direct measurements of electrical properties on Martian materials have been performed.

Clay-based polymer nanocomposites: research and commercial development.

PubMed

Zeng, Q H; Yu, A B; Lu, G Q; Paul, D R

2005-10-01

This paper reviews the recent research and development of clay-based polymer nanocomposites. Clay minerals, due to their unique layered structure, rich intercalation chemistry and availability at low cost, are promising nanoparticle reinforcements for polymers to manufacture low-cost, lightweight and high performance nanocomposites. We introduce briefly the structure, properties and surface modification of clay minerals, followed by the processing and characterization techniques of polymer nanocomposites. The enhanced and novel properties of such nanocomposites are then discussed, including mechanical, thermal, barrier, electrical conductivity, biodegradability among others. In addition, their available commercial and potential applications in automotive, packaging, coating and pigment, electrical materials, and in particular biomedical fields are highlighted. Finally, the challenges for the future are discussed in terms of processing, characterization and the mechanisms governing the behaviour of these advanced materials.

Properties of mixed molybdenum oxide iridium oxide thin films synthesized by spray pyrolysis

NASA Astrophysics Data System (ADS)

Patil, P. S.; Kawar, R. K.; Sadale, S. B.; Inamdar, A. I.; Deshmukh, H. P.

2006-09-01

Molybdenum-doped iridium oxide thin films have been deposited onto corning glass- and fluorine-doped tin oxide coated corning glass substrates at 350 °C by using a pneumatic spray pyrolysis technique. An aqueous solution of 0.01 M ammonium molybdate was mixed with 0.01 M iridium trichloride solution in different volume proportions and the resultant solution was used as a precursor solution for spraying. The as-deposited samples were annealed at 600 °C in air medium for 1 h. The structural, electrical and optical properties of as-deposited and annealed Mo-doped iridium oxide were studied and values of room temperature electrical resistivity, and thermoelectric power were estimated. The as-deposited samples with 2% Mo doping exhibit more pronounced electrochromism than other samples, including pristine Ir oxide.

Structures with high number density of carbon nanotubes and 3-dimensional distribution

NASA Technical Reports Server (NTRS)

Chen, Zheng (Inventor); Tzeng, Yonhua (Inventor)

2002-01-01

A composite is described having a three dimensional distribution of carbon nanotubes. The critical aspect of such composites is a nonwoven network of randomly oriented fibers connected at their junctions to afford macropores in the spaces between the fibers. A variety of fibers may be employed, including metallic fibers, and especially nickel fibers. The composite has quite desirable properties for cold field electron emission applications, such as a relatively low turn-on electric field, high electric field enhancement factors, and high current densities. The composites of this invention also show favorable properties for other an electrode applications. Several methods, which also have general application in carbon nanotube production, of preparing these composites are described and employ a liquid feedstock of oxyhydrocarbons as carbon nanotube precursors.

Petrophysical evaluation of subterranean formations

DOEpatents

Klein, James D; Schoderbek, David A; Mailloux, Jason M

2013-05-28

Methods and systems are provided for evaluating petrophysical properties of subterranean formations and comprehensively evaluating hydrate presence through a combination of computer-implemented log modeling and analysis. Certain embodiments include the steps of running a number of logging tools in a wellbore to obtain a variety of wellbore data and logs, and evaluating and modeling the log data to ascertain various petrophysical properties. Examples of suitable logging techniques that may be used in combination with the present invention include, but are not limited to, sonic logs, electrical resistivity logs, gamma ray logs, neutron porosity logs, density logs, NRM logs, or any combination or subset thereof.

The electric and thermoelectric properties of Cu(II)-Schiff base nano-complexes

NASA Astrophysics Data System (ADS)

Ibrahim, E. M. M.; Abdel-Rahman, Laila H.; Abu-Dief, Ahmed M.; Elshafaie, A.; Hamdan, Samar Kamel; Ahmed, A. M.

2018-05-01

The physical properties, such as electric and optical properties, of metal-Schiff base complexes have been widely investigated. However, their thermoelectric (TE) properties remain unreported. This work presents Cu(II)-Schiff base complexes as promising materials for TE power generation. Therefore, three Cu(II)-Schiff base complexes (namely, [Cu(C32H22N4O2)].3/2H2O, [Cu(C23H17N4O7Br)], and [Cu(C27H22N4O8)].H2O) have been synthesized in nanosized scale. The electric and TE properties have been studied and comprehensive discussions have been presented to promote the nano-complexes (NCs) practical applications in the field of TE power generation. The electrical measurements confirm that the NCs are semiconductors and the electrical conduction process is governed by intermolecular and intramolecular transfer of the charge carriers. The TE measurements reveal that the Cu(II)-Schiff base NCs are nondegenerate P-type semiconductors. The measured Seebeck coefficient values were higher compared to the values reported in previous works for other organic materials indicating that the complexes under study are promising candidates for theremoelectric applications if the electrical conductivity could be enhanced.

A Novel SPM Probe with MOS Transistor and Nano Tip for Surface Electric Properties

NASA Astrophysics Data System (ADS)

Lee, Sang H.; Lim, Geunbae; Moon, Wonkyu

2007-03-01

In this paper, the novel SPM (Scanning Probe Microscope) probe with the planar MOS (Metal-Oxide-Semiconductor) transistor and the FIB (Focused Ion Beam) nano tip is fabricated for the surface electric properties. Since the MOS transistor has high working frequency, the device can overcome the speed limitation of EFM (Electrostatic Force Microscope) system. The sensitivity is also high, and no bulky device such as lock-in-amplifier is required. Moreover, the nano tip with nanometer scale tip radius is fabricated with FIB system, and the resolution can be improved. Therefore, the probe can rapidly detect small localized electric properties with high sensitivity and high resolution. The MOS transistor is fabricated with the common semiconductor process, and the nano tip is grown by the FIB system. The planar structure of the MOS transistor makes the fabrication process easier, which is the advantage on the commercial production. Various electric signals are applied using the function generator, and the measured data represent the well-established electric properties of the device. It shows the promising aspect of the local surface electric property detection with high sensitivity and high resolution.

Thermal properties of alkali-activated aluminosilicates with CNT admixture

NASA Astrophysics Data System (ADS)

Zmeskal, Oldrich; Trhlikova, Lucie; Fiala, Lukas; Florian, Pavel; Cerny, Robert

2017-07-01

Material properties of electrically conductive cement-based materials with increased attention paid on electric and thermal properties were often studied in the last years. Both electric and thermal properties play an important role thanks to their possible utilization in various practical applications (e.g. snow-melting systems or building structures monitoring systems without the need of an external monitoring system). The DC/AC characteristics depend significantly on the electrical resistivity and the electrical capacity of bulk materials. With respect to the DC/AC characteristics of cement-based materials, such materials can be basically classified as electric insulators. In order to enhance them, various conductive admixtures such as those based on different forms of carbon, can be used. Typical representatives of carbon-based admixtures are carbon nanotubes (CNT), carbon fibers (CF), graphite powder (GP) and carbon black (CB). With an adequate amount of such admixtures, electric properties significantly change and new materials with higher added value can be prepared. However, other types of materials can be enhanced in the same way. Alkali-activated aluminosilicates (AAA) based on blast furnace slag are materials with high compressive strength comparable with cement-based materials. Moreover, the price of slag is lower than of Portland cement. Therefore, this paper deals with the study of thermal properties of this promising material with different concentrations of CNT. Within the paper a simple method of basic thermal parameters determination based on the thermal transient response to a heat power step is presented.

Enhanced mechanical, thermal, and electric properties of graphene aerogels via supercritical ethanol drying and high-temperature thermal reduction.

PubMed

Cheng, Yehong; Zhou, Shanbao; Hu, Ping; Zhao, Guangdong; Li, Yongxia; Zhang, Xinghong; Han, Wenbo

2017-05-03

Graphene aerogels with high surface areas, ultra-low densities and thermal conductivities have been prepared to exploit their wide applications from pollution adsorption to energy storage, supercapacitor, and thermal insulation. However, the low mechanical properties, poor thermal stability and electric conductivity restrict these aerogels' applications. In this paper, we prepared mechanically strong graphene aerogels with large BET surface areas, low thermal conductivities, high thermal stability and electric conductivities via hydrothermal reduction and supercritical ethanol drying. Annealing at 1500 °C resulted in slightly increased thermal conductivity and further improvement in mechanical properties, oxidation temperature and electric conductivity of the graphene aerogel. The large BET surface areas, together with strong mechanical properties, low thermal conductivities, high thermal stability and electrical conductivities made these graphene aerogels feasible candidates for use in a number of fields covering from batteries to sensors, electrodes, lightweight conductor and insulation materials.

Influences of film thickness on the structural, electrical and optical properties of CuAlO2 thin films

NASA Astrophysics Data System (ADS)

Dong, Guobo; Zhang, Ming; Wang, Mei; Li, Yingzi; Gao, Fangyuan; Yan, Hui; Diao, Xungang

2014-07-01

CuAlO2 films with different thickness were prepared by the radio frequency magnetron sputtering technique. The structural, electrical and optical properties of CuAlO2 were studied by X-ray diffraction, atomic force microscope, UV-Vis double-beam spectrophotometer and Hall measurements. The results indicate that the single phase hexagonal CuAlO2 is formed and the average grain size of CuAlO2 films increases with increasing film thickness. The results also exhibit that the lowering of bandgap and the increase of electrical conductivity of CuAlO2 films with the increase of their thickness, which are attributed to the improvement of the grain size and the anisotropic electrical property. According to the electrical and optical properties, the biggest figure of merit is achieved for the CuAlO2 film with the appropriate thickness of 165 nm.

Frontiers of Glass Science. Scientific Research Conference Held at Los Angeles, California on 16-18 July 1980.

DTIC Science & Technology

1981-01-01

AFB, DC 20332 102 NIFE r A- 14. MONI1TORING AGEN1CY N AME & AD1DRESS(II dllforenl I,,,,, Co111,11rng 0111c) IS SE7UPITY CL~ASS. t, ’?.,r Unclaiis s if...Optical and Electrical Properties , Amorphous Semiconductors and Electrical Proper-ties, Lens Common Class5es, ind ni nd Fur’acos and ’!-em-:ci’ Y...Scholze H. Kawazoe THURSDAY, 17 JULY SESSION II. OPTICAL & ELECTRICAL PROPERTIES S. Ovshinsky J. Isard SESSION III. AMORPHOUS SEMICONDUCTORS & ELECTRICAL

1D Piezoelectric Material Based Nanogenerators: Methods, Materials and Property Optimization

PubMed Central

Li, Xing; Sun, Mei; Wei, Xianlong; Shan, Chongxin

2018-01-01

Due to the enhanced piezoelectric properties, excellent mechanical properties and tunable electric properties, one-dimensional (1D) piezoelectric materials have shown their promising applications in nanogenerators (NG), sensors, actuators, electronic devices etc. To present a clear view about 1D piezoelectric materials, this review mainly focuses on the characterization and optimization of the piezoelectric properties of 1D nanomaterials, including semiconducting nanowires (NWs) with wurtzite and/or zinc blend phases, perovskite NWs and 1D polymers. Specifically, the piezoelectric coefficients, performance of single NW-based NG and structure-dependent electromechanical properties of 1D nanostructured materials can be respectively investigated through piezoresponse force microscopy, atomic force microscopy and the in-situ scanning/transmission electron microcopy. Along with the introduction of the mechanism and piezoelectric properties of 1D semiconductor, perovskite materials and polymers, their performance improvement strategies are summarized from the view of microstructures, including size-effect, crystal structure, orientation and defects. Finally, the extension of 1D piezoelectric materials in field effect transistors and optoelectronic devices are simply introduced. PMID:29570639

Role of Morphological Structure, Doping, and Coating of Different Materials in the Sensing Characteristics of Humidity Sensors

PubMed Central

Tripathy, Ashis; Pramanik, Sumit; Cho, Jongman; Santhosh, Jayasree; Osman, Noor Azuan Abu

2014-01-01

The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability. PMID:25256110

Joining engineering ceramics

NASA Astrophysics Data System (ADS)

Loehman, Ronald E.

Methods for joining ceramics are outlined with attention given to their fundamental properties, and some examples of ceramic bonding in engineering ceramic systems are presented. Ceramic-ceramic bonds using no filler material include diffusion and electric-field bonding and ceramic welding, and bonds with filler materials can be provided by Mo-Mn brazing, microwave joining, and reactive nonmetallic liquid bonding. Ceramic-metal joints can be effected with filler material by means of the same ceramic-ceramic processes and without filler material by means of use of molten glass or diffusion bonding. Key properties of the bonding processes include: bonds with discontinuous material properties, energies that are positive relative to the bulk material, and unique chemical and mechanical properties. The processes and properties are outlined for ceramic-metal joints and for joining silicon nitride, and the factors that control wetting, adhesion, and reaction on the atomic scale are critical for establishing successful joints.

Accidental deaths caused by electricity in Sweden, 1975-2000.

PubMed

Lindström, Richard; Bylund, Per-Olof; Eriksson, Anders

2006-11-01

This study analyzes accidental fatalities caused by electricity--at work and during leisure time--to evaluate risk factors, the role of alcohol, and to identify possible preventive strategies. In Sweden, data on fatalities by electrocution from 1975 through 2000 were collected from the National Cause-of-Death Register. Additional cases were found in the archives of The Swedish National Electrical Safety Board. Suicides and deaths by lightning were excluded. Two hundred and eighty-five deaths were found, including occupational (n=132), leisure time (n=151), and unknown (n=2). Most deaths were caused by aerial power lines, and the most common place for an electrical injury was a railway area or residential property. Postmortem blood from 20% (n=47) of the tested cases was found positive for alcohol, and these persons were killed mainly during leisure time. During the study period, the overall incidence of electricity-related fatalities has decreased, in spite of increased use of electricity. This indicates that safety improvements have been successful.

Electronic-Power-Transformer Design Guide

NASA Technical Reports Server (NTRS)

Schwarze, G. E.; Lagadinos, J. C.; Ahearn, J. F.

1983-01-01

Compilation of information on design procedures, electrical properties, and fabrication. Guide provides information on design procedures; magnetic and insulating material electrical properties; impregnating, encapsulating and processing techniques.

Effect of rapid thermal annealing on the structural and electrical properties of RF sputtered CCTO thin film

NASA Astrophysics Data System (ADS)

Tripathy, N.; Das, K. C.; Ghosh, S. P.; Bose, G.; Kar, J. P.

2017-02-01

CaCu3Ti4O12 (CCTO) thin films have been deposited by RF magnetron sputtering on silicon substrates at room temperature. As-deposited thin films were subjected to rapid thermal annealing (RTA) at different temperatures ranging from 850°C to 1000°C. XRD and capacitance - voltage studies indicate that the structural and electrical properties of CCTO thin film strongly depend upon the annealing temperature. XRD pattern of CCTO thin film annealed at 950°C revealed the polycrystalline nature with evolutions of microstructures. Electrical properties of the dielectric films were investigated by fabricating Al/CCTO/Si metal oxide semiconductor structure. Electrical properties were found to be deteriorated with increasing in annealing temperature.

Variation of the electric properties along the diaphysis of bovine femoral bone.

PubMed

De Mercato, G; García Sánchez, F J

1991-07-01

A preliminary study is presented of the variability of the electric properties, in the axial, tangential and radial directions, as a function of position in the diaphysis of a femoral bovine bone. The measurements were carried out at three frequencies: 100 Hz, 10 kHz and 1 MHz. It is shown that both the conductivity and the permittivity exhibit significant variations along the diaphysis, and increase in magnitude towards the epiphyses. From this study, the variation of the electric properties cannot be clearly and directly ascribed to the longitudinal variability of the total volumetric fluid content of the bone. The results reflect the orthotropic nature of the electric properties, at any given location, and indicate a position-dependent tendency towards axis symmetry.

Controlling dielectric and relaxor-ferroelectric properties for energy storage by tuning Pb0.92La0.08Zr0.52Ti0.48O3 film thickness.

PubMed

Brown, Emery; Ma, Chunrui; Acharya, Jagaran; Ma, Beihai; Wu, Judy; Li, Jun

2014-12-24

The energy storage properties of Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films grown via pulsed laser deposition were evaluated at variable film thickness of 125, 250, 500, and 1000 nm. These films show high dielectric permittivity up to ∼1200. Cyclic I-V measurements were used to evaluate the dielectric properties of these thin films, which not only provide the total electric displacement, but also separate contributions from each of the relevant components including electric conductivity (D1), dielectric capacitance (D2), and relaxor-ferroelectric domain switching polarization (P). The results show that, as the film thickness increases, the material transits from a linear dielectric to nonlinear relaxor-ferroelectric. While the energy storage per volume increases with the film thickness, the energy storage efficiency drops from ∼80% to ∼30%. The PLZT films can be optimized for different energy storage applications by tuning the film thickness to optimize between the linear and nonlinear dielectric properties and energy storage efficiency.

Controlling Dielectric and Relaxor-Ferroelectric Properties for Energy Storage by Tuning Pb 0.92La 0.08Zr 0.52Ti 0.48O 3 Film Thickness

DOE PAGES

Brown, Emery; Ma, Chunrui; Acharya, Jagaran; ...

2014-12-24

The energy storage properties of Pb 0.92La 0.08Zr 0.52Ti 0.48O 3 (PLZT) films grown via pulsed laser deposition were evaluated at variable film thickness of 125, 250, 500, and 1000 nm. These films show high dielectric permittivity up to ~1200. Cyclic I–V measurements were used to evaluate the dielectric properties of these thin films, which not only provide the total electric displacement, but also separate contributions from each of the relevant components including electric conductivity (D1), dielectric capacitance (D2), and relaxor-ferroelectric domain switching polarization (P). Our results show that, as the film thickness increases, the material transits from a linearmore » dielectric to nonlinear relaxor-ferroelectric. And while the energy storage per volume increases with the film thickness, the energy storage efficiency drops from ~80% to ~30%. The PLZT films can be optimized for different energy storage applications by tuning the film thickness to optimize between the linear and nonlinear dielectric properties and energy storage efficiency.« less

Electronic and Thermoelectric Properties of Ternary Chalcohalide Semiconductors: First Principles Study

NASA Astrophysics Data System (ADS)

Khan, Wilayat; Hussain, Sajjad; Minar, Jan; Azam, Sikander

2018-02-01

Ternary chalcohalides have been widely utilized for different device applications. The thermoelectric properties of SbSI, SbSeI and SbSBr have been investigated by theoretical simulations, and the findings have been performed using BoltzTraP code, based on semi-classical Boltzmann transport theory. In this study, we simulated the electronic structures using the Englo-Vosko generalized gradient approximation employed in the WIEN2k program. From the electronic band structures, we found a combination of light and heavy bands around the Fermi level in the valence band, which strongly affect the effective masses of the carriers. The entire thermoelectric parameters, like the electrical, the electronic part of the thermal conductivities, the Seebeck coefficient and the power factor have been analysed as functions of temperature and chemical potential. The correlation between the effective masses and the thermoelectric properties is also included in the discussion because the effective mass reveals the mobility of the carriers which in turn affect the thermoelectric properties. The substitution of sulfur reveals high electrical conductivity and a smaller Seebeck coefficient based on effective mass leads to the increase in the power factor.

Fractal Electronic Circuits Assembled From Nanoclusters

NASA Astrophysics Data System (ADS)

Fairbanks, M. S.; McCarthy, D.; Taylor, R. P.; Brown, S. A.

2009-07-01

Many patterns in nature can be described using fractal geometry. The effect of this fractal character is an array of properties that can include high internal connectivity, high dispersivity, and enhanced surface area to volume ratios. These properties are often desirable in applications and, consequently, fractal geometry is increasingly employed in technologies ranging from antenna to storm barriers. In this paper, we explore the application of fractal geometry to electrical circuits, inspired by the pervasive fractal structure of neurons in the brain. We show that, under appropriate growth conditions, nanoclusters of Sb form into islands on atomically flat substrates via a process close to diffusion-limited aggregation (DLA), establishing fractal islands that will form the basis of our fractal circuits. We perform fractal analysis of the islands to determine the spatial scaling properties (characterized by the fractal dimension, D) of the proposed circuits and demonstrate how varying growth conditions can affect D. We discuss fabrication approaches for establishing electrical contact to the fractal islands. Finally, we present fractal circuit simulations, which show that the fractal character of the circuit translates into novel, non-linear conduction properties determined by the circuit's D value.

Thermal to electricity conversion using thermal magnetic properties

DOEpatents

West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

2010-04-27

A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

Electrorheological suspensions of laponite in oil: rheometry studies.

PubMed

Parmar, K P S; Méheust, Y; Schjelderupsen, Børge; Fossum, J O

2008-03-04

We have studied the effect of an external direct current (DC) electric field ( approximately 1 kV/mm) on the rheological properties of colloidal suspensions consisting of aggregates of laponite particles in a silicone oil. Microscopy observations show that, under application of an electric field greater than a triggering electric field Ec approximately 0.6 kV/mm, laponite aggregates assemble into chain- and/or columnlike structures in the oil. Without an applied electric field, the steady-state shear behavior of such suspensions is Newtonian-like. Under application of an electric field larger than Ec, it changes dramatically as a result of the changes in the microstructure: a significant yield stress is measured, and under continuous shear the fluid is shear-thinning. The rheological properties, in particular the dynamic and static shear stress, were studied as a function of particle volume fraction for various strengths (including null) of the applied electric field. The flow curves at constant shear rate can be scaled with respect to both the particle fraction and electric field strength onto a master curve. This scaling is consistent with simple scaling arguments. The shape of the master curve accounts for the system's complexity; it approaches a standard power-law model at high Mason numbers. Both dynamic and static yield stresses are observed to depend on the particle fraction Phi and electric field E as PhibetaEalpha, with alpha approximately 1.85 and beta approximately 1 and 1.70 for the dynamic and static yield stresses, respectively. The yield stress was also determined as the critical stress at which there occurs a bifurcation in the rheological behavior of suspensions that are submitted to a constant shear stress; a scaling law with alpha approximately 1.84 and beta approximately 1.70 was obtained. The effectiveness of the latter technique confirms that such electrorheological (ER) fluids can be studied in the framework of thixotropic fluids. The method is very reproducible; we suggest that it could be used routinely for studying ER fluids. The measured overall yield stress behavior of the suspensions may be explained in terms of standard conduction models for electrorheological systems. Interesting prospects include using such systems for guided self-assembly of clay nanoparticles.

Brownian dynamics simulation of rigid particles of arbitrary shape in external fields.

PubMed

Fernandes, Miguel X; de la Torre, José García

2002-12-01

We have developed a Brownian dynamics simulation algorithm to generate Brownian trajectories of an isolated, rigid particle of arbitrary shape in the presence of electric fields or any other external agents. Starting from the generalized diffusion tensor, which can be calculated with the existing HYDRO software, the new program BROWNRIG (including a case-specific subprogram for the external agent) carries out a simulation that is analyzed later to extract the observable dynamic properties. We provide a variety of examples of utilization of this method, which serve as tests of its performance, and also illustrate its applicability. Examples include free diffusion, transport in an electric field, and diffusion in a restricting environment.

A simplified regional-scale electromagnetic induction - Salinity calibration model using ANOCOVA modeling techniques

USDA-ARS?s Scientific Manuscript database

Directed soil sampling based on geospatial measurements of apparent soil electrical conductivity (ECa) is a potential means of characterizing the spatial variability of any soil property that influences ECa including soil salinity, water content, texture, bulk density, organic matter, and cation exc...

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.

Delocalization error and "functional tuning" in Kohn-Sham calculations of molecular properties.

PubMed

Autschbach, Jochen; Srebro, Monika

2014-08-19

Kohn-Sham theory (KST) is the "workhorse" of numerical quantum chemistry. This is particularly true for first-principles calculations of ground- and excited-state properties for larger systems, including electronic spectra, electronic dynamic and static linear and higher order response properties (including nonlinear optical (NLO) properties), conformational or dynamic averaging of spectra and response properties, or properties that are affected by the coupling of electron and nuclear motion. This Account explores the sometimes dramatic impact of the delocalization error (DE) and possible benefits from the use of long-range corrections (LC) and "tuning" of functionals in KST calculations of molecular ground-state and response properties. Tuning refers to a nonempirical molecule-specific determination of adjustable parameters in functionals to satisfy known exact conditions, for instance, that the energy of the highest occupied molecular orbital (HOMO) should be equal to the negative vertical ionization potential (IP) or that the energy as a function of fractional electron numbers should afford straight-line segments. The presentation is given from the viewpoint of a chemist interested in computations of a variety of molecular optical and spectroscopic properties and of a theoretician developing methods for computing such properties with KST. In recent years, the use of LC functionals, functional tuning, and quantifying the DE explicitly have provided valuable insight regarding the performance of KST for molecular properties. We discuss a number of different molecular properties, with examples from recent studies from our laboratory and related literature. The selected properties probe different aspects of molecular electronic structure. Electric field gradients and hyperfine coupling constants can be exquisitely sensitive to the DE because it affects the ground-state electron density and spin density distributions. For π-conjugated molecules, it is shown how the DE manifests itself either in too strong or too weak delocalization of localized molecular orbitals (LMOs). Optical rotation is an electric-magnetic linear response property that is calculated in a similar fashion as the electric polarizability, but it is more sensitive to approximations and can benefit greatly from tuning and small DE. Hyperpolarizabilities of π-conjugated "push-pull" systems are examples of NLO properties that can be greatly improved by tuning of range-separated exchange (RSE) functionals, in part due to improved charge-transfer excitation energies. On-going work on band gap predictions is also mentioned. The findings may provide clues for future improvements of KST because different molecular properties exhibit varying sensitivity to approximations in the electronic structure model. The utility of analyzing molecular properties and the impact of the DE in terms of LMOs, representing "chemist's orbitals" such as individual lone pairs and bonds, is highlighted.

Predicting the Electric Field Distribution in the Brain for the Treatment of Glioblastoma

PubMed Central

Miranda, Pedro C.; Mekonnen, Abeye; Salvador, Ricardo; Basser, Peter J.

2014-01-01

The use of alternating electric fields has been recently proposed for the treatment of recurrent glioblastoma. In order to predict the electric field distribution in the brain during the application of such tumor treating fields (TTF), we constructed a realistic head model from MRI data and placed transducer arrays on the scalp to mimic an FDA-approved medical device. Values for the tissue dielectric properties were taken from the literature; values for the device parameters were obtained from the manufacturer. The finite element method was used to calculate the electric field distribution in the brain. We also included a “virtual lesion” in the model to simulate the presence of an idealized tumor. The calculated electric field in the brain varied mostly between 0.5 and 2.0 V/cm and exceeded 1.0 V/cm in 60% of the total brain volume. Regions of local field enhancement occurred near interfaces between tissues with different conductivities wherever the electric field was perpendicular to those interfaces. These increases were strongest near the ventricles but were also present outside the tumor’s necrotic core and in some parts of the gray matter-white matter interface. The electric field values predicted in this model brain are in reasonably good agreement with those that have been shown to reduce cancer cell proliferation in vitro. The electric field distribution is highly non-uniform and depends on tissue geometry and dielectric properties. This could explain some of the variability in treatment outcomes. The proposed modeling framework could be used to better understand the physical basis of TTF efficacy through retrospective analysis and to improve TTF treatment planning. PMID:25003941

Predicting the electric field distribution in the brain for the treatment of glioblastoma

NASA Astrophysics Data System (ADS)

Miranda, Pedro C.; Mekonnen, Abeye; Salvador, Ricardo; Basser, Peter J.

2014-08-01

The use of alternating electric fields has been recently proposed for the treatment of recurrent glioblastoma. In order to predict the electric field distribution in the brain during the application of such tumor treating fields (TTF), we constructed a realistic head model from MRI data and placed transducer arrays on the scalp to mimic an FDA-approved medical device. Values for the tissue dielectric properties were taken from the literature; values for the device parameters were obtained from the manufacturer. The finite element method was used to calculate the electric field distribution in the brain. We also included a ‘virtual lesion’ in the model to simulate the presence of an idealized tumor. The calculated electric field in the brain varied mostly between 0.5 and 2.0 V cm - 1 and exceeded 1.0 V cm - 1 in 60% of the total brain volume. Regions of local field enhancement occurred near interfaces between tissues with different conductivities wherever the electric field was perpendicular to those interfaces. These increases were strongest near the ventricles but were also present outside the tumor’s necrotic core and in some parts of the gray matter-white matter interface. The electric field values predicted in this model brain are in reasonably good agreement with those that have been shown to reduce cancer cell proliferation in vitro. The electric field distribution is highly non-uniform and depends on tissue geometry and dielectric properties. This could explain some of the variability in treatment outcomes. The proposed modeling framework could be used to better understand the physical basis of TTF efficacy through retrospective analysis and to improve TTF treatment planning.

Predicting the electric field distribution in the brain for the treatment of glioblastoma.

PubMed

Miranda, Pedro C; Mekonnen, Abeye; Salvador, Ricardo; Basser, Peter J

2014-08-07

The use of alternating electric fields has been recently proposed for the treatment of recurrent glioblastoma. In order to predict the electric field distribution in the brain during the application of such tumor treating fields (TTF), we constructed a realistic head model from MRI data and placed transducer arrays on the scalp to mimic an FDA-approved medical device. Values for the tissue dielectric properties were taken from the literature; values for the device parameters were obtained from the manufacturer. The finite element method was used to calculate the electric field distribution in the brain. We also included a 'virtual lesion' in the model to simulate the presence of an idealized tumor. The calculated electric field in the brain varied mostly between 0.5 and 2.0 V cm( - 1) and exceeded 1.0 V cm( - 1) in 60% of the total brain volume. Regions of local field enhancement occurred near interfaces between tissues with different conductivities wherever the electric field was perpendicular to those interfaces. These increases were strongest near the ventricles but were also present outside the tumor's necrotic core and in some parts of the gray matter-white matter interface. The electric field values predicted in this model brain are in reasonably good agreement with those that have been shown to reduce cancer cell proliferation in vitro. The electric field distribution is highly non-uniform and depends on tissue geometry and dielectric properties. This could explain some of the variability in treatment outcomes. The proposed modeling framework could be used to better understand the physical basis of TTF efficacy through retrospective analysis and to improve TTF treatment planning.

Rational design of aromatic surfactants for graphene/natural rubber latex nanocomposites with enhanced electrical conductivity.

PubMed

Mohamed, Azmi; Ardyani, Tretya; Abu Bakar, Suriani; Sagisaka, Masanobu; Umetsu, Yasushi; Hamon, J J; Rahim, Bazura Abdul; Esa, Siti Rahmah; Abdul Khalil, H P S; Mamat, Mohamad Hafiz; King, Stephen; Eastoe, Julian

2018-04-15

Graphene nanoplatelets (GNPs) can be dispersed in natural rubber matrices using surfactants. The stability and properties of these composites can be optimized by the choice of surfactants employed as stabilizers. Surfactants can be designed and synthesized to have enhanced compatibility with GNPs as compared to commercially available common surfactants. Including aromatic groups in the hydrophobic chain termini improves graphene compatibility of surfactants, which is expected to increase with the number of aromatic moieties per surfactant molecule. Hence, it is of interest to study the relationship between molecular structure, dispersion stability and electrical conductivity enhancement for single-, double-, and triple-chain anionic graphene-compatible surfactants. Graphene-philic surfactants, bearing two and three chains phenylated at their chain termini, were synthesized and characterized by proton nuclear magnetic resonance ( 1 H NMR) spectroscopy. These were used to formulate and stabilize dispersion of GNPs in natural rubber latex matrices, and the properties of systems comprising the new phenyl-surfactants were compared with commercially available surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS). Raman spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM) were used to study structural properties of the materials. Electrical conductivity measurements and Zeta potential measurements were used to assess the relationships between surfactant architecture and nanocomposite properties. Small-angle neutron scattering (SANS) was used to study self-assembly structure of surfactants. Of these different surfactants, the tri-chain aromatic surfactant TC3Ph3 (sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3phenylpropoxy)carbonyl) pentane-2-sulfonate) was shown to be highly graphene-compatible (nanocomposite electrical conductivity = 2.22 × 10 -5  S cm -1 ), demonstrating enhanced electrical conductivity over nine orders of magnitude higher than neat natural rubber-latex matrix (1.51 × 10 -14  S cm -1 ). Varying the number of aromatic moieties in the surfactants appears to cause significant differences to the final properties of the nanocomposites. Copyright © 2018 Elsevier Inc. All rights reserved.

Dielectric and Electromechanical Properties of Polyurethane and Polydimethylsiloxane Blends and their Nanocomposites

NASA Astrophysics Data System (ADS)

Cakmak, Enes

Conventional means of converting electrical energy to mechanical work are generally considered too noisy and bulky for many contemporary technologies such as microrobotic, microfluidic, and haptic devices. Dielectric electroactive polymers (D-EAPs) constitude a growing class of electroactive polymers (EAP) that are capable of producing mechanica work induced by an applied electric field. D-EAPs are considered remarkably efficient and well suited for a wide range of applications, including ocean-wave energy harvesters and prosthetic devices. However, the real-world application of D-EAPs is very limited due to a number of factors, one of which is the difficulty of producing high actuation strains at acceptably low electric fields. D-EAPs are elastomeric polymers and produce large strain response induced by external electric field. The electromechanical properties of D-EAPs depend on the dielectric properties and mechanical properties of the D-EAP. In terms of dielectric behavior, these actuators require a high dielectric constant, low dielectric loss, and high dielectric strength to produce an improved actuation response. In addition to their dielectric properties, the mechanical properties of D-EAPs, such as elastic moduli and hysteresis, are also of importance. Therefore, material properties are a key feature of D-EAP technology. DE actuator materials reported in the literature cover many types of elastomers and their composites formed with dielectric fillers. Along with polymeric matrix materials, various ceramic, metal, and organic fillers have been employed in enhancing dielectric behavior of DEs. This work describes an effort to characterize elastomer blends and composites of different matrix and dielectric polymer fillers according to their dielectric, mechanical, and electromechanical responses. This dissertation focuses on the development and characterization of polymer-polymer blends and composites from a high-k polyurethane (PU) and polydimethylsiloxane (PDMS) elastomers. Two different routes were followed with respect to elastomer processing: The first is a simple solution blending of the two types of elastomers, and the second is based on preparation of composites from PU nanofiber webs and PDMS elastomer. Both the blends and the nanofiber web composites showed improved dielectric and actuation characteristics.

Electrical and geochemical properties of tufa deposits as related to mineral composition in the South Western Desert, Egypt

NASA Astrophysics Data System (ADS)

Gomaa, Mohamed M.; Abou El-Anwar, Esmat A.

2015-06-01

The geochemical, petrographical, and electrical properties of rocks are essential to the investigation of the properties of minerals. In this paper we will try to present a study of the A. C. electrical properties of carbonate rock samples and their relation to petrographical and geochemical properties. Samples were collected from four formations from the Bir Dungul area, in the South Western Desert, Egypt. The electrical properties of the samples were measured using a non-polarizing electrode, at room temperature (~28 °C), and at a relative atmospheric humidity of (~45%), in the frequency range from 42 Hz to 5 MHz. The changes in the electrical properties were argued to the change in mineral composition. Generally, the electrical properties of rocks are changed due to many factors e.g., grain size, mineral composition, grain shape and inter-granular relations between grains. The dielectric constant of samples decreases with frequency, and increases with conductor concentration. Also, the conductivity increases with an increase of continuous conductor paths between electrodes. The petrographical and geochemical studies reveal that the deposition of the tufa deposits occurred in shallow lakes accompanied by a high water table, an alkaline spring recharge and significant vegetation cover. Diagenetically, tufa deposits were subjected to early and late diagenesis. Petrography and geochemistry studies indicated that the area of tufa deposits was deposited under the control of bacterial activity. Geochemically, the Sr content indicates that the tufa deposits formed from dissolved bicarbonate under the control of microbes and bacterial activity.

Influence of Illumination on the Electrical Properties of p-(ZnMgTe/ZnTe:N)/CdTe/n-(CdTe:I)/GaAs Heterojunction Grown by Molecular Beam Epitaxy (MBE)

NASA Astrophysics Data System (ADS)

Jum'h, I.; Abd El-Sadek, M. S.; Al-Taani, H.; Yahia, I. S.; Karczewski, G.

2017-02-01

Heterostructure p-(ZnMgTe/ZnTe:N)/CdTe/n-(CdTe:I)/GaAs was evaporated using molecular beam epitaxy and investigated for photovoltaic energy conversion application. The electrical properties of the studied heterostructure were measured and characterized in order to understand the relevant electrical transport mechanisms. Electrical properties derived from the current-voltage ( I- V) characteristics of solar cells provide essential information necessary for the analysis of performance losses and device efficiency. I- V characteristics are investigated in dark conditions and under different light intensities. All the electrical and power parameters of the heterostructure were measured, calculated and explained.

Actuators Based on Liquid Crystalline Elastomer Materials

PubMed Central

Jiang, Hongrui; Li, Chensha; Huang, Xuezhen

2013-01-01

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCEs materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic field, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the property of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described. PMID:23648966

Actuators based on liquid crystalline elastomer materials

NASA Astrophysics Data System (ADS)

Jiang, Hongrui; Li, Chensha; Huang, Xuezhen

2013-05-01

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCE materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic fields, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the properties of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described.

Electric-field-driven switching of individual magnetic skyrmions

NASA Astrophysics Data System (ADS)

Hsu, Pin-Jui; Kubetzka, André; Finco, Aurore; Romming, Niklas; von Bergmann, Kirsten; Wiesendanger, Roland

2017-02-01

Controlling magnetism with electric fields is a key challenge to develop future energy-efficient devices. The present magnetic information technology is mainly based on writing processes requiring either local magnetic fields or spin torques, but it has also been demonstrated that magnetic properties can be altered on the application of electric fields. This has been ascribed to changes in magnetocrystalline anisotropy caused by spin-dependent screening and modifications of the band structure, changes in atom positions or differences in hybridization with an adjacent oxide layer. However, the switching between states related by time reversal, for example magnetization up and down as used in the present technology, is not straightforward because the electric field does not break time-reversal symmetry. Several workarounds have been applied to toggle between bistable magnetic states with electric fields, including changes of material composition as a result of electric fields. Here we demonstrate that local electric fields can be used to switch reversibly between a magnetic skyrmion and the ferromagnetic state. These two states are topologically inequivalent, and we find that the direction of the electric field directly determines the final state. This observation establishes the possibility to combine electric-field writing with the recently envisaged skyrmion racetrack-type memories.

The features of self-assembling organic bilayers important to the formation of anisotropic inorganic materials in microgravity conditions

NASA Technical Reports Server (NTRS)

Talham, Daniel R.; Adair, James H.

2005-01-01

Materials with directional properties are opening new horizons in a variety of applications including chemistry, electronics, and optics. Structural, optical, and electrical properties can be greatly augmented by the fabrication of composite materials with anisotropic microstructures or with anisotropic particles uniformly dispersed in an isotropic matrix. Examples include structural composites, magnetic and optical recording media, photographic film, certain metal and ceramic alloys, and display technologies including flat panel displays. The new applications and the need for model particles in scientific investigations are rapidly out-distancing the ability to synthesize anisotropic particles with specific chemistries and narrowly distributed physical characteristics (e.g. size distribution, shape, and aspect ratio).

Laser-gyro materials studies

NASA Astrophysics Data System (ADS)

Covino, J.; Bennett, J. M.

1986-03-01

Material properties of low-expansion glass and glass-ceramic materials have been measured. The materials that have been characterized are ultralow-expansion (ULE) type 7971 quartz, a new glass-ceramic material RLA 559,122 from Corning Glass Works, fused quartz from General Electric, Zerodur from Schott Glaswerke, and Cervit C-101 from Owens-Illinois. Characterization has included measurements of X-ray powder diffraction patterns, some elemental analyses, helium permeability, thermal expansion, particle-size distributions, optical properties, and optical finish studies.

Electrically driven hybrid photonic metamaterials for multifunctional control

NASA Astrophysics Data System (ADS)

Kang, Lei; Liu, Liu; Campbell, Sawyer D.; Yue, Taiwei; Ren, Qiang; Mayer, Theresa S.; Werner, Douglas H.

2017-08-01

The unique light-matter interaction in metamaterials, a type of artificial medium in which the geometrical features of subunits dominate their optical responses, have been utilized to achieve exotic material properties that are rare or nonexistent in natural materials. Furthermore, to extend their behaviors, active materials have been introduced into metamaterial systems to advance tunability, switchability and nonlinearity. Nevertheless, practical examples of versatile photonic metamaterials remain exceedingly rare for two main reasons. On the one hand, in sharp contrast to the broad material options available at lower frequencies, it is less common to find active media in the optical regime that can provide pronounced dielectric property changes under external stimuli, such as electric and magnetic fields. Vanadium dioxide (VO2), offering a large refractive index variation over a broad frequency range due to its near room temperature insulator-to-metal transition (IMT), has been favored in recent studies on tunable metamaterials. On the other hand, it turns out that regulating responses of hybrid metamaterials to external forces in an integrated manner is not a straightforward task. Recently, metamaterial-enabled devices (i.e., metadevices) with `self-sufficient' or `self-contained' electrical and optical properties have enabled complex functionalities. Here, we present a design methodology along with the associated experimental validation of a VO2 thin film integrated optical metamaterial absorber as a hybrid photonic platform for electrically driven multifunctional control, including reflectance switching, a rewritable memory process and manageable localized camouflage. The nanoengineered topologically continuous metal structure simultaneously supports the optical resonance and electrical functionality that actuates the phase transition in VO2 through the process of Joule heating. This work provides a universal approach to creating self-sufficient and highly-versatile nanophotonic systems.

Electronic and Magnetic Structures, Magnetic Hyperfine Fields and Electric Field Gradients in UX3 (X = In, Tl, Pb) Intermetallic Compounds

NASA Astrophysics Data System (ADS)

Khan, Sajid; Yazdani-Kachoei, Majid; Jalali-Asadabadi, Saeid; Farooq, Muhammad Bilal; Ahmad, Iftikhar

2018-02-01

Cubic uranium compounds such as UX3 (X is a non-transition element of groups IIIA or IVA) exhibit highly diverse magnetic properties, including Pauli paramagnetism, spin fluctuation and anti-ferromagnetism. In the present paper, we explore the structural, electronic and magnetic properties as well as the hyperfine fields (HFFs) and electric field gradients (EFGs) with quadrupole coupling constant of UX3 (X = In, Tl, Pb) compounds using local density approximation, Perdew-Burke-Ernzerhof parametrization of generalized gradient approximation (PBE-GGA) including the Hubbard U parameter (GGA + U), a revised version of PBE-GGA that improves equilibrium properties of densely packed solids and their surfaces (PBEsol-GGA), and a hybrid functional (HF-PBEsol). The spin orbit-coupling calculations have been added to investigate the relativistic effect of electrons in these materials. The comparison between the experimental parameters and our calculated structural parameters we confirm the consistency and effectiveness of our theoretical tools. The computed magnetic moments show that magnetic moment increases from indium to lead in the UX3 family, and all these compounds are antiferromagnetic in nature. The EFGs and HFFs, as well as the quadrupole coupling constant of UX3 (X = In, Tl, Pb), are discussed in detail. These properties primarily originate from f and p states of uranium and post-transition sites.

Multi-modality gellan gum-based tissue-mimicking phantom with targeted mechanical, electrical, and thermal properties.

PubMed

Chen, Roland K; Shih, A J

2013-08-21

This study develops a new class of gellan gum-based tissue-mimicking phantom material and a model to predict and control the elastic modulus, thermal conductivity, and electrical conductivity by adjusting the mass fractions of gellan gum, propylene glycol, and sodium chloride, respectively. One of the advantages of gellan gum is its gelling efficiency allowing highly regulable mechanical properties (elastic modulus, toughness, etc). An experiment was performed on 16 gellan gum-based tissue-mimicking phantoms and a regression model was fit to quantitatively predict three material properties (elastic modulus, thermal conductivity, and electrical conductivity) based on the phantom material's composition. Based on these material properties and the regression model developed, tissue-mimicking phantoms of porcine spinal cord and liver were formulated. These gellan gum tissue-mimicking phantoms have the mechanical, thermal, and electrical properties approximately equivalent to those of the spinal cord and the liver.

Observation of Failure and Domain Switching in Lead Zirconate Titanate Ceramics

NASA Astrophysics Data System (ADS)

Okayasu, Mitsuhiro; Sugiyama, Eriko; Sato, Kazuto; Mizuno, Mamoru

The mechanical and electrical properties (electromechanical coupling coefficient, piezoelectric constant and dielectric constant) of lead zirconate titanate (PZT) ceramics are investigated during mechanical static and cyclic loading. There are several failure characteristics which can alter the material properties of PZT ceramics. The elastic constant increases and electrical properties decrease with increasing the applied load. This is due to the internal strain arising from the domain switching. In this case, 90° domain switching occurs anywhere in the samples as the sample is loaded. It is also apparent that electrogenesis occurs several times during cyclic loading to the final fracture. This occurrence is related to the domain switching. The elastic constant and electrical properties can decrease because of crack generation in the PZT ceramics. Moreover, the elastic constant increases with increase of the mechanical load and decreases with decrease of the load. On the contrary, the opposite sense of change of the electrical properties is observed.

Intracellular Physiology of the Rat Suprachiasmatic Nucleus: Electrical Properties, Neurotransmission, and Effects of Neuromodulators

DTIC Science & Technology

1992-01-10

Physiology of the Rat Suprachiasmatic Nucleus: Electrical Properties, Neurotransmission, and Effects of Neuromodulators . I-f 12. PERSONAL AUTHOR(S) F...interplay between intrinsic electrophysiological properties, amino-acid-mediated synaptic transmission, and neuromodulation . We have continued to study the

Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

NASA Astrophysics Data System (ADS)

Yamaura, Kazunari

2016-04-01

High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO3, LiOsO3, and Na2OsO4, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal-insulator transition in NaOsO3, a ferroelectric-like transition in LiOsO3, and high-temperature ferrimagnetism driven by a local structural distortion in Ca2FeOsO6 may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices.

Advanced thermoelectric materials with enhanced crystal lattice structure and methods of preparation

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Caillat, Thierry F. (Inventor); Borshchevsky, Alexander (Inventor)

1998-01-01

New skutterudite phases including Ru.sub.0.5 Pd.sub.0.5 Sb.sub.3, RuSb.sub.2 Te, and FeSb.sub.2 Te, have been prepared having desirable thermoelectric properties. In addition, a novel thermoelectric device has been prepared using skutterudite phase Fe.sub.0.5 Ni.sub.0.5 Sb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using powder metallurgy techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities and good Seebeck coefficients. These materials have low thermal conductivity and relatively low electrical resistivity, and are good candidates for low temperature thermoelectric applications.

Hyperfine field, electric field gradient, quadrupole coupling constant and magnetic properties of challenging actinide digallide

NASA Astrophysics Data System (ADS)

Khan, Sajid; Yazdani-Kachoei, M.; Jalali-Asadabadi, S.; Ahmad, Iftikhar

2017-12-01

In this paper, we explore the structural and magnetic properties as well as electric field gradient (EFG), hyperfine field (HFF) and quadrupole coupling constant in actinide digallide AcGa2 (Ac = U, Np, Pu) using LDA, GGA, LDA+U, GGA+U and hybrid functional with Wu-Cohen Generalized Gradient approximation HF-WC. Relativistic effects of the electrons are considered by including spin-orbit coupling. The comparison of the calculated structural parameters and magnetic properties with the available experimental results confirms the consistency and hence effectiveness of our theoretical tools. The calculated magnetic moments demonstrate that UGa2 and NpGa2 are ferromagnetic while PuGa2 is antiferromagnetic in nature. The EFG of AcGa2 is reported for the first time. The HFF, EFG and quadrupole coupling constant in AcGa2 (Ac = U, Np, Pu) are mainly originated from f-f and p-p contributions of Ac atom and p-p contribution of Ga atom.

Tongue muscle plasticity following hypoglossal nerve stimulation in aged rats

PubMed Central

Connor, Nadine P.; Russell, John A.; Jackson, Michelle A.; Kletzien, Heidi; Wang, Hao; Schaser, Allison J.; Leverson, Glen E.; Zealear, David L.

2012-01-01

Introduction Age-related decreases in tongue muscle mass and strength have been reported. It may be possible to prevent age-related tongue muscle changes using neuromuscular electrical stimulation (NMES). Our hypothesis was that alterations in muscle contractile properties and myosin heavy chain composition would be found following NMES. Methods Fifty-four young, middle-aged and old Fischer 344/Brown Norway rats were included. Twenty-four rats underwent bilateral electrical stimulation of the hypoglossal nerves for 8 weeks and were compared with control or sham rats. Muscle contractile properties and myosin heavy chain (MHC) in the genioglossus (GG), styloglossus (SG) and hyoglossus (HG) muscles were examined. Results In comparison with unstimulated control rats, we found reduced muscle fatigue, increased contraction and half decay times and increased twitch and tetanic tension. Increased Type I MHC was found, except for GG in old and middle-aged rats. Discussion Transitions in tongue muscle contractile properties and phenotype were found following NMES. PMID:23169566

Electrical, Thermal, and Magnetic Properties of Single Crystal CaMn2O4 Marokite

NASA Astrophysics Data System (ADS)

White, B. D.; Neumeier, J. J.; Souza, J. A.; Chiorescu, C.; Cohn, J. L.

2008-03-01

CaMn2O4 was first described [1] in 1963 as a natural mineral called Marokite. Since its discovery, it has been studied as a minor structural impurity phase in CMR- related CaMnO3 and for its structural similarities to high-pressure phases of spinel-oxide compounds. However, little attention has previously been paid to physical properties beyond its temperature-dependent magnetization. We will present a detailed physical properties study of CaMn2O4 single crystals grown by the optical floating zone method. [2] These measurements, several of which display anisotropy as a result of an orthorhombic crystal structure, include electrical transport, thermal transport, thermal expansion, heat capacity, and magnetization. [1] C. Gaudefroy, G. Jouravsky, F. Permingeat, Bull. Soc. Franc. Min'er. Crist. 86 (1963) 359. [2] B. D. White, C. A. M. dos Santos, J. A. Souza, K. J. McClellan, J. J. Neumeier submitted to J. Cryst. Growth.

A comparison of thermoelectric phenomena in diverse alloy systems

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

Cook, Bruce

1999-01-01

The study of thermoelectric phenomena in solids provides a wealth of opportunity for exploration of the complex interrelationships between structure, processing, and properties of materials. As thermoelectricity implies some type of coupled thermal and electrical behavior, it is expected that a basic understanding of transport behavior in materials is the goal of such a study. However, transport properties such as electrical resistivity and thermal diffusivity cannot be fully understood and interpreted without first developing an understanding of the material's preparation and its underlying structure. It is the objective of this dissertation to critically examine a number of diverse systems inmore » order to develop a broad perspective on how structure-processing-property relationships differ from system to system, and to discover the common parameters upon which any good thermoelectric material is based. The alloy systems examined in this work include silicon-germanium, zinc oxide, complex intermetallic compounds such as the half-Heusler MNiSn, where M = Ti, Zr, or Hf, and rare earth chalcogenides.« less

Divergent effect of electric fields on the mechanical property of water-filled carbon nanotubes with an application as a nanoscale trigger

NASA Astrophysics Data System (ADS)

Ye, Hongfei; Zheng, Yonggang; Zhou, Lili; Zhao, Junfei; Zhang, Hongwu; Chen, Zhen

2018-01-01

Polar water molecules exhibit extraordinary phenomena under nanoscale confinement. Through the application of an electric field, a water-filled carbon nanotube (CNT) that has been successfully fabricated in the laboratory is expected to have distinct responses to the external electricity. Here, we examine the effect of electric field direction on the mechanical property of water-filled CNTs. It is observed that a longitudinal electric field enhances, but the transverse electric field reduces the elastic modulus and critical buckling stress of water-filled CNTs. The divergent effect of the electric field is attributed to the competition between the axial and circumferential pressures induced by polar water molecules. Furthermore, it is notable that the transverse electric field could result in an internal pressure with elliptical distribution, which is an effective and convenient approach to apply nonuniform pressure on nanochannels. Based on pre-strained water-filled CNTs, we designed a nanoscale trigger with an evident and rapid height change initiated by switching the direction of the electric field. The reported finding provides a foundation for an electricity-controlled property of nanochannels filled with polar molecules and provides an insight into the design of nanoscale functional devices.

Divergent effect of electric fields on the mechanical property of water-filled carbon nanotubes with an application as a nanoscale trigger.

PubMed

Ye, Hongfei; Zheng, Yonggang; Zhou, Lili; Zhao, Junfei; Zhang, Hongwu; Chen, Zhen

2017-12-11

Polar water molecules exhibit extraordinary phenomena under nanoscale confinement. Through the application of an electric field, a water-filled carbon nanotube (CNT) that has been successfully fabricated in the laboratory is expected to have distinct responses to the external electricity. Here, we examine the effect of electric field direction on the mechanical property of water-filled CNTs. It is observed that a longitudinal electric field enhances, but the transverse electric field reduces the elastic modulus and critical buckling stress of water-filled CNTs. The divergent effect of the electric field is attributed to the competition between the axial and circumferential pressures induced by polar water molecules. Furthermore, it is notable that the transverse electric field could result in an internal pressure with elliptical distribution, which is an effective and convenient approach to apply nonuniform pressure on nanochannels. Based on pre-strained water-filled CNTs, we designed a nanoscale trigger with an evident and rapid height change initiated by switching the direction of the electric field. The reported finding provides a foundation for an electricity-controlled property of nanochannels filled with polar molecules and provides an insight into the design of nanoscale functional devices.

Nickel hydroxides and related materials: a review of their structures, synthesis and properties

PubMed Central

Hall, David S.; Lockwood, David J.; Bock, Christina; MacDougall, Barry R.

2015-01-01

This review article summarizes the last few decades of research on nickel hydroxide, an important material in physics and chemistry, that has many applications in engineering including, significantly, batteries. First, the structures of the two known polymorphs, denoted as α-Ni(OH)2 and β-Ni(OH)2, are described. The various types of disorder, which are frequently present in nickel hydroxide materials, are discussed including hydration, stacking fault disorder, mechanical stresses and the incorporation of ionic impurities. Several related materials are discussed, including intercalated α-derivatives and basic nickel salts. Next, a number of methods to prepare, or synthesize, nickel hydroxides are summarized, including chemical precipitation, electrochemical precipitation, sol–gel synthesis, chemical ageing, hydrothermal and solvothermal synthesis, electrochemical oxidation, microwave-assisted synthesis, and sonochemical methods. Finally, the known physical properties of the nickel hydroxides are reviewed, including their magnetic, vibrational, optical, electrical and mechanical properties. The last section in this paper is intended to serve as a summary of both the potentially useful properties of these materials and the methods for the identification and characterization of ‘unknown’ nickel hydroxide-based samples. PMID:25663812

Polymer-Single Wall Carbon Nanotube Composites for Potential Spacecraft Applications

NASA Technical Reports Server (NTRS)

Park, C.; Ounaies, Z.; Watson, K. A.; Pawlowski, K.; Lowther, S. E.; Connell, J. W.; Siochi, E. J.; Harrison, J. S.; St.Clair, T. L.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

Polymer-single wall carbon nanotube (SWNT) composite films were prepared and characterized as part of an effort to develop polymeric materials with improved combinations of properties for potential use on future spacecraft. Next generation spacecraft will require ultra-lightweight materials that possess specific and unique combinations of properties such as radiation and atomic oxygen resistance, low solar absorptivity, high thermal emissitivity, electrical conductivity, tear resistance, ability to be folded and seamed, and good mechanical properties. The objective of this work is to incorporate sufficient electrical conductivity into space durable polyimides to mitigate static charge build-up. The challenge is to obtain this level of conductivity (10(exp -8) S/cm) without degrading other properties of importance, particularly optical transparency. Several different approaches were attempted to fully disperse the SWNTs into the polymer matrix. These included high shear mixing, sonication, and synthesizing the polymers in the presence of pre-dispersed SWNTs. Acceptable levels of conductivity were obtained at loading levels less than one tenth weight percent SWNT without significantly sacrificing optical properties. Characterization of the nanocomposite films and the effect of SWNT concentration and dispersion on the conductivity, solar absorptivity, thermal emissivity, mechanical and thermal properties were discussed. Fibers and non-woven porous mats of SWNT reinforced polymer nanocomposite were produced using electrospinning.

Superconducting selenides intercalated with organic molecules: synthesis, crystal structure, electric and magnetic properties, superconducting properties, and phase separation in iron based-chalcogenides and hybrid organic-inorganic superconductors

NASA Astrophysics Data System (ADS)

Krzton-Maziopa, Anna; Pesko, Edyta; Puzniak, Roman

2018-06-01

Layered iron-based superconducting chalcogenides intercalated with molecular species are the subject of intensive studies, especially in the field of solid state chemistry and condensed matter physics, because of their intriguing chemistry and tunable electric and magnetic properties. Considerable progress in the research, revealing superconducting inorganic–organic hybrid materials with transition temperatures to superconducting state, T c, up to 46 K, has been brought in recent years. These novel materials are synthesized by low-temperature intercalation of molecular species, such as solvates of alkali metals and nitrogen-containing donor compounds, into layered FeSe-type structure. Both the chemical nature as well as orientation of organic molecules between the layers of inorganic host, play an important role in structural modifications and may be used for fine tuning of superconducting properties. Furthermore, a variety of donor species compatible with alkali metals, as well as the possibility of doping also in the host structure (either on Fe or Se sites), makes this system quite flexible and gives a vast array of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed with a particular attention paid to the influence of the unique nature of intercalating species on the crystal structure and physical properties of the hybrid inorganic–organic materials. To get a full picture of these materials, a comprehensive description of the most effective chemical and electrochemical methods, utilized for synthesis of intercalated species, with critical evaluation of their strong and weak points, related to feasibility of synthesis, phase purity, crystal size and morphology of final products, is included as well.

Dielectric and nonlinear current-voltage characteristics of rare-earth doped CaCu3Ti4O12 ceramics

NASA Astrophysics Data System (ADS)

Liu, Laijun; Fang, Liang; Huang, Yanmin; Li, Yunhua; Shi, Danping; Zheng, Shaoying; Wu, Shuangshuang; Hu, Changzheng

2011-11-01

CaCu3Ti4O12 (CCTO) ceramics doped with rare earth (RE) oxides, including Y2O3, La2O3, Eu2O3, and Gd2O3, were prepared by the traditional solid-state reaction method in order to investigate the effect of RE oxide dopants on the electrical properties as a varistor. The phase identification and morphology of the ceramics were investigated by x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. A high voltage measuring unit and precision impedance analyzer were used to determine the nonohmic (J-E) behaviors and measure the dielectric properties and impedance spectroscopy of the ceramics, respectively. The results showed that RE oxides enhanced greatly the breakdown electric flied but reduced the nonlinear coefficient and the mean grain size of CCTO ceramics. There was a good linear relationship between ln J and E1/2, which demonstrated that the Schottky barrier should exist at the grain boundary. A double Schottky barrier model composed of a depletion layer and a negative charge sheet was proposed, analogous to the barrier model for ZnO varistors. The depletion layer width determined by diffusion distance of RE ions and the effective surface states played important roles on the electrical properties of the ceramics.

Ultra-capacitor flexible films with tailored dielectric constants using electric field assisted assembly of nanoparticles.

PubMed

Batra, Saurabh; Cakmak, Miko

2015-12-28

In this study, the chaining and preferential alignment of barium titanate nanoparticles (100 nm) through the thickness direction of a polymer matrix in the presence of an electric field is shown. Application of an AC electric field in a well-dispersed solution leads to the formation of chains of nanoparticles in discrete rows oriented with their primary axis in the E-field direction due to dielectrophoresis. The change in the orientation of these chains was quantified through statistical analysis of SEM images and was found to be dependent on E-field, frequency and viscosity. When a DC field is applied a distinct layer consisting of dense particles was observed with micro-computed tomography. These studies show that the increase in DC voltage leads to increase in the thickness of the particle rich layer along with the packing density also increasing. Increasing the mutual interactions between particles due to the formation of particle chains in the "Z"-direction decreases the critical percolation concentration above which substantial enhancement of properties occurs. This manufacturing method therefore shows promise to lower the cost of the products for a range of applications including capacitors by either enhancing the dielectric properties for a given concentration or reduces the concentration of nanoparticles needed for a given property.

Dielectric properties of carbon nanotubes/epoxy composites.

PubMed

Peng, Jin-Ping; Zhang, Hui; Tang, Long-Cheng; Jia, Yu; Zhang, Zhong

2013-02-01

Material with high dielectric properties possesses the effect of energy storage and electric field homogenization, which plays an important role in the electrical and electronics domain, especially in the capacitor, electrical machinery and cable realm. In this paper, epoxy-based nanocomposites with high dielectric constant were fabricated by adding pristine and ozone functionalized multi-wall carbon nanotubes (MWCNTs). In the process-related aspect, the favorable technological parameter was obtained via reasonable arrangement and consideration of the dispersing methods including high-speed stirring and three-roller mill. As a result, a uniform dispersion status of MWCNTs in matrix has been guaranteed, which was observed by scanning and transmission electron microscopy. Meanwhile, the influence of different MWCNTs contents and diverse frequencies on the dielectric properties was compared. It was found that the dielectric constant of nano-composites decreased gradually with the increasing of frequency (10(3)-10(6) Hz). Moreover, as the content of MWCNTs increasing, the dielectric constant reached to a maximum of about 1,328 at 10(3) Hz when the pristine MWCNTs content was 0.5 wt.%. Accordingly, the DC conductivity results could interpret the peak value phenomenon by percolation threshold of MWCNTs. In addition, at the fixed content, the dielectric constant of epoxy-based nano-composites with ozone functionalized MWCNTs was lower than that of pristine ones.

Graphene Aerogel Templated Fabrication of Phase Change Microspheres as Thermal Buffers in Microelectronic Devices.

PubMed

Wang, Xuchun; Li, Guangyong; Hong, Guo; Guo, Qiang; Zhang, Xuetong

2017-11-29

Phase change materials, changing from solid to liquid and vice versa, are capable of storing and releasing a large amount of thermal energy during the phase change, and thus hold promise for numerous applications including thermal protection of electronic devices. Shaping these materials into microspheres for additional fascinating properties is efficient but challenging. In this regard, a novel phase change microsphere with the design for electrical-regulation and thermal storage/release properties was fabricated via the combination of monodispersed graphene aerogel microsphere (GAM) and phase change paraffin. A programmable method, i.e., coupling ink jetting-liquid marbling-supercritical drying (ILS) techniques, was demonstrated to produce monodispersed graphene aerogel microspheres (GAMs) with precise size-control. The resulting GAMs showed ultralow density, low electrical resistance, and high specific surface area with only ca. 5% diameter variation coefficient, and exhibited promising performance in smart switches. The phase change microspheres were obtained by capillary filling of phase change paraffin inside the GAMs and exhibited excellent properties, such as low electrical resistance, high latent heat, well sphericity, and thermal buffering. Assembling the phase change microsphere into the microcircuit, we found that this tiny device was quite sensitive and could respond to heat as low as 0.027 J.

Method for making an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.; Pal, Uday B.

1996-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

26 CFR 31.3231(a)-1 - Who are employers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... insubstantial. (d) The term “employer” does not include any street, interurban, or suburban electric railway... Railroad Retirement Tax Act (Chapter 22, Internal Revenue Code of 1954) General Provisions § 31.3231(a)-1... connection with— (a) The transportation of passengers or property by railroad, or (b) The receipt, delivery...

Variation in the electrical properties of ion beam irradiated cadmium selenate nanowires

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

Chauhan, R. P., E-mail: chauhanrpc@gmail.com; Narula, Chetna; Panchal, Suresh

The key feature of nanowires consists in the pronounced change in properties induced by the low dimensionality and high surface to volume ratio. The study of electrical transport properties of nanowires is important for electronic device applications. Energetic ions create changes, which may be structural or chemical, in a material along their track and these changes might alter the material’s properties. The demand of the modern technology is to understand the effect of radiation on the different properties of the material for its further applications. The present study is on the high-energy Nickel ion beam (160 MeV Ni{sup +12}) induced modificationsmore » in the electrical and structural properties of the cadmium selenate nanowires. An enhancement in the electrical conductivity of irradiated wires was observed as the ion fluence was increased especially in the forward I–V characteristics. The creation of defects by ion irradiation and the synergy of the ions during their passage in the sample with the intrinsic charge carriers may be responsible for the variation in the transport properties of the irradiated nanowires.« less

Optical and electrical properties of indium tin oxide films near their laser damage threshold [Electrical and optical properties of indium tin oxide films under multi-pulse laser irradiation at 1064 nm

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

Yoo, Jae -Hyuck; Lange, Andrew; Bude, Jeff

In this paper, we investigated whether the optical and electrical properties of indium tin oxide (ITO) films are degraded under laser irradiation below their laser ablation threshold. While performing multi-pulse laser damage experiments on a single ITO film (4.7 ns, 1064 nm, 10 Hz), we examined the optical and electrical properties in situ. A decrease in reflectance was observed prior to laser damage initiation. However, under sub-damage threshold irradiation, conductivity and reflectance of the film were maintained without measurable degradation. This indicates that ITO films in optoelectronic devices may be operated below their lifetime laser damage threshold without noticeable performancemore » degradation.« less

Optical and electrical properties of indium tin oxide films near their laser damage threshold [Electrical and optical properties of indium tin oxide films under multi-pulse laser irradiation at 1064 nm

DOE PAGES

Yoo, Jae -Hyuck; Lange, Andrew; Bude, Jeff; ...

2017-02-10

In this paper, we investigated whether the optical and electrical properties of indium tin oxide (ITO) films are degraded under laser irradiation below their laser ablation threshold. While performing multi-pulse laser damage experiments on a single ITO film (4.7 ns, 1064 nm, 10 Hz), we examined the optical and electrical properties in situ. A decrease in reflectance was observed prior to laser damage initiation. However, under sub-damage threshold irradiation, conductivity and reflectance of the film were maintained without measurable degradation. This indicates that ITO films in optoelectronic devices may be operated below their lifetime laser damage threshold without noticeable performancemore » degradation.« less

The electrical properties of zero-gravity processed immiscibles

NASA Technical Reports Server (NTRS)

Lacy, L. L.; Otto, G. H.

1974-01-01

When dispersed or mixed immiscibles are solidified on earth, a large amount of separation of the constituents takes place due to differences in densities. However, when the immiscibles are dispersed and solidified in zero-gravity, density separation does not occur, and unique composite solids can be formed with many new and promising electrical properties. By measuring the electrical resistivity and superconducting critical temperature, Tc, of zero-g processed Ga-Bi samples, it has been found that the electrical properties of such materials are entirely different from the basic constituents and the ground control samples. Our results indicate that space processed immiscible materials may form an entirely new class of electronic materials.

Electric Conduction in Solids: a Pedagogical Approach Supported by Laboratory Measurements and Computer Modelling Environments

NASA Astrophysics Data System (ADS)

Bonura, A.; Capizzo, M. C.; Fazio, C.; Guastella, I.

2008-05-01

In this paper we present a pedagogic approach aimed at modeling electric conduction in semiconductors, built by using NetLogo, a programmable modeling environment for building and exploring multi-agent systems. `Virtual experiments' are implemented to confront predictions of different microscopic models with real measurements of electric properties of matter, such as resistivity. The relations between these electric properties and other physical variables, like temperature, are, then, analyzed.

Dielectric and electrical properties of binary mixtures of 1-butyl-3-methylimadazolium and water in the frequency range 20 Hz to 2 MHz

NASA Astrophysics Data System (ADS)

Barot, D. K.; Chaube, H. A.; Rana, V. A.

2017-05-01

The complex relative dielectric function ɛ*(ω) = ɛ'-jɛ″ of binary mixture of 1-Butyl-3-methylimadazolium (BMiCl) with water of varying concentration have been measured using Precision LCR meter in the frequency range 20 Hz to 2 MHz at 293.15 K. The dielectric and electrical properties of BMiCl and water are represented in terms of electrical conductivity σ*(ω) and complex relative dielectric function ɛ*(ω). To describe the relationship of the electrical conductivity with concentration, the empirical Casteel-Amis (C-A) equation was used. The influence of concentration variation of BMiCl in water to the various electrical parameters was discussed. All of these presentations are used to explore various processes contributed in the electrical/dielectric properties of the mixtures of BMiCl and water.

Dielectric and Piezoelectric Properties of Barium-substituted Sr1.9Ca0.1NaNb5O15 Ceramics

NASA Astrophysics Data System (ADS)

Xie, Rong-Jun; Akimune, Yoshio; Wang, Ruiping; Hirosaki, Naoto; Nishimura, Toshiyuki

2003-12-01

Highly dense piezoelectric ceramics of tungsten bronze-type (Sr1.9Ca0.1)1-0.5xBaxNaNb5O15 (where x=0.1--0.8) were prepared by spark plasma sintering. The crystallographic parameters, dielectric behaviors and piezoelectric properties of the sintered ceramics were investigated, and the effects of the Ba substitution on these electrical properties were discussed. The structural analysis and the electrical property measurements indicate a morphotropic phase boundary (MPB)-like phenomenon at x=0.4--0.5. In all compositions, a diffuse phase transition and a relaxor behavior are observed. The electrical properties are found to be crystallographically dependent.

High to ultra-high power electrical energy storage.

PubMed

Sherrill, Stefanie A; Banerjee, Parag; Rubloff, Gary W; Lee, Sang Bok

2011-12-14

High power electrical energy storage systems are becoming critical devices for advanced energy storage technology. This is true in part due to their high rate capabilities and moderate energy densities which allow them to capture power efficiently from evanescent, renewable energy sources. High power systems include both electrochemical capacitors and electrostatic capacitors. These devices have fast charging and discharging rates, supplying energy within seconds or less. Recent research has focused on increasing power and energy density of the devices using advanced materials and novel architectural design. An increase in understanding of structure-property relationships in nanomaterials and interfaces and the ability to control nanostructures precisely has led to an immense improvement in the performance characteristics of these devices. In this review, we discuss the recent advances for both electrochemical and electrostatic capacitors as high power electrical energy storage systems, and propose directions and challenges for the future. We asses the opportunities in nanostructure-based high power electrical energy storage devices and include electrochemical and electrostatic capacitors for their potential to open the door to a new regime of power energy.

Tuning the Electronic, Optical, and Magnetic Properties of Monolayer GaSe with a Vertical Electric Field

NASA Astrophysics Data System (ADS)

Ke, Congming; Wu, Yaping; Guo, Guang-Yu; Lin, Wei; Wu, Zhiming; Zhou, Changjie; Kang, Junyong

2018-04-01

Inspired by two-dimensional material with their unique physical properties and innovative device applications, here we report a design framework on monolayer GaSe, an important member of the two-dimensional material family, in an effort to tune the electronic, optical, and magnetic properties through a vertical electric field. A transition from indirect to direct band gap in monolayer GaSe is found with an electric field of 0.09 V /Å . The giant Stark effect results in a reduction of the band gap with a Stark coefficient of 3.54 Å. Optical and dielectric properties of monolayer GaSe are dependent on the vertical electric field. A large regulation range for polarization E ∥c ^ is found for the static dielectric constant. The optical anisotropy with the dipole transition from E ∥c ^ to E ⊥c ^ is achieved. Induced by the spin-orbit coupling, spin-splitting energy at the valence band maximum increases linearly with the electric field. The effective mass of holes is highly susceptible to the vertical electric field. Switchable spin-polarization features in spin texture of monolayer GaSe are predicted. The tunable electronic, optical, and magnetic properties of monolayer GaSe hold great promise for applications in both the optoelectronic and spintronic devices.

Mechanical and electrical properties of laminates for high performance printed wiring boards

NASA Astrophysics Data System (ADS)

Guiles, Chester L.

The physical and electrical properties of laminate boards intended for high-performance applications are reviewed with particular reference to the coefficient of thermal expansion, dielectric constant, and characteristic impedance. It is shown, in particular, that the electrical properties can be tailored to some extent by using various conbinations of basic board materials, such as copper foil, fiberglass fabric, glass fabric, epoxy resin, polyimide resin, aluminum sheet, Kevlar and quartz fabrics, copper-invar-copper, and alumina-ceramic.

Advantages of soft subdural implants for the delivery of electrochemical neuromodulation therapies to the spinal cord

NASA Astrophysics Data System (ADS)

Capogrosso, Marco; Gandar, Jerome; Greiner, Nathan; Moraud, Eduardo Martin; Wenger, Nikolaus; Shkorbatova, Polina; Musienko, Pavel; Minev, Ivan; Lacour, Stephanie; Courtine, Grégoire

2018-04-01

Objective. We recently developed soft neural interfaces enabling the delivery of electrical and chemical stimulation to the spinal cord. These stimulations restored locomotion in animal models of paralysis. Soft interfaces can be placed either below or above the dura mater. Theoretically, the subdural location combines many advantages, including increased selectivity of electrical stimulation, lower stimulation thresholds, and targeted chemical stimulation through local drug delivery. However, these advantages have not been documented, nor have their functional impact been studied in silico or in a relevant animal model of neurological disorders using a multimodal neural interface. Approach. We characterized the recruitment properties of subdural interfaces using a realistic computational model of the rat spinal cord that included explicit representation of the spinal roots. We then validated and complemented computer simulations with electrophysiological experiments in rats. We additionally performed behavioral experiments in rats that received a lateral spinal cord hemisection and were implanted with a soft interface. Main results. In silico and in vivo experiments showed that the subdural location decreased stimulation thresholds compared to the epidural location while retaining high specificity. This feature reduces power consumption and risks of long-term damage in the tissues, thus increasing the clinical safety profile of this approach. The hemisection induced a transient paralysis of the leg ipsilateral to the injury. During this period, the delivery of electrical stimulation restricted to the injured side combined with local chemical modulation enabled coordinated locomotor movements of the paralyzed leg without affecting the non-impaired leg in all tested rats. Electrode properties remained stable over time, while anatomical examinations revealed excellent bio-integration properties. Significance. Soft neural interfaces inserted subdurally provide the opportunity to deliver electrical and chemical neuromodulation therapies using a single, bio-compatible and mechanically compliant device that effectively alleviates locomotor deficits after spinal cord injury.

Variation in dielectric properties due to pathological changes in human liver.

PubMed

Peyman, Azadeh; Kos, Bor; Djokić, Mihajlo; Trotovšek, Blaž; Limbaeck-Stokin, Clara; Serša, Gregor; Miklavčič, Damijan

2015-12-01

Dielectric properties of freshly excised human liver tissues (in vitro) with several pathological conditions including cancer were obtained in frequency range 100 MHz-5 GHz. Differences in dielectric behavior of normal and pathological tissues at microwave frequencies are discussed based on histological information for each tissue. Data presented are useful for many medical applications, in particular nanosecond pulsed electroporation techniques. Knowledge of dielectric properties is vital for mathematical calculations of local electric field distribution inside electroporated tissues and can be used to optimize the process of electroporation for treatment planning procedures. © 2015 Wiley Periodicals, Inc.

Polyhydroxyalkanoate/carbon nanotube nanocomposites: flexible electrically conducting elastomers for neural applications.

PubMed

Vallejo-Giraldo, Catalina; Pugliese, Eugenia; Larrañaga, Aitor; Fernandez-Yague, Marc A; Britton, James J; Trotier, Alexandre; Tadayyon, Ghazal; Kelly, Adriona; Rago, Ilaria; Sarasua, Jose-Ramon; Dowd, Eilís; Quinlan, Leo R; Pandit, Abhay; Biggs, Manus Jp

2016-10-01

Medium chain length-polyhydroxyalkanoate/multi-walled carbon nanotube (MWCNTs) nanocomposites with a range of mechanical and electrochemical properties were fabricated via assisted dispersion and solvent casting, and their suitability as neural interface biomaterials was investigated. Mechanical and electrical properties of medium chain length-polyhydroxyalkanoate/MWCNTs nanocomposite films were evaluated by tensile test and electrical impedance spectroscopy, respectively. Primary rat mesencephalic cells were seeded on the composites and quantitative immunostaining of relevant neural biomarkers, and electrical stimulation studies were performed. Incorporation of MWCNTs to the polymeric matrix modulated the mechanical and electrical properties of resulting composites, and promoted differential cell viability, morphology and function as a function of MWCNT concentration. This study demonstrates the feasibility of a green thermoplastic MWCNTs nanocomposite for potential use in neural interfacing applications.

Quantum Electronic Solids

DTIC Science & Technology

2012-03-07

signal processing with smaller sizes and unique properties Nanoelectronics: NTs, graphene, diamond, SiC for sensing, logic & memory storage 3...synthesized i-n graphene heterojunctions 19 DISTRIBUTION A: Approved for public release; distribution is unlimited. Electrical Properties of...boundaries in polycrystalline samples Polycrystalline graphene can have similar (as much as 90%) electrical properties (conductance and mobility

Surface dynamics of voltage-gated ion channels.

PubMed

Heine, Martin; Ciuraszkiewicz, Anna; Voigt, Andreas; Heck, Jennifer; Bikbaev, Arthur

2016-07-03

Neurons encode information in fast changes of the membrane potential, and thus electrical membrane properties are critically important for the integration and processing of synaptic inputs by a neuron. These electrical properties are largely determined by ion channels embedded in the membrane. The distribution of most ion channels in the membrane is not spatially uniform: they undergo activity-driven changes in the range of minutes to days. Even in the range of milliseconds, the composition and topology of ion channels are not static but engage in highly dynamic processes including stochastic or activity-dependent transient association of the pore-forming and auxiliary subunits, lateral diffusion, as well as clustering of different channels. In this review we briefly discuss the potential impact of mobile sodium, calcium and potassium ion channels and the functional significance of this for individual neurons and neuronal networks.

Effects of fluctuations on electrical properties of gap-junction connected cells in the turtle retina.

PubMed

Louis, E; Degli Esposti Boschi, C; Ortega, G; Andreu, E; Fernández, E; Sánchez-Andrés, J V

2002-04-19

Electrical properties of gap-junction connected cells (input voltage and length constant) are shown to depend strongly on fluctuations in membrane and contact conductances. This opens new possibilities and incorporates a further difficulty to the analysis of electrophysiological data, since four, instead of two, parameters (the average values and the magnitude of fluctuations of the two conductances) have to be used in fitting the experimental data. The discussion is illustrated by investigating the effects of dopamine on signal spreading in horizontal cells of turtle retina, assuming a linear cell arrangement. It is shown that while a standard fitting with the average values of the two conductances leads to the conclusion that both are equally affected by dopamine, including fluctuations allows fitting the data by varying just the average contact conductance plus the magnitude of fluctuations.

Surface dynamics of voltage-gated ion channels

PubMed Central

Heine, Martin; Ciuraszkiewicz, Anna; Voigt, Andreas; Heck, Jennifer; Bikbaev, Arthur

2016-01-01

ABSTRACT Neurons encode information in fast changes of the membrane potential, and thus electrical membrane properties are critically important for the integration and processing of synaptic inputs by a neuron. These electrical properties are largely determined by ion channels embedded in the membrane. The distribution of most ion channels in the membrane is not spatially uniform: they undergo activity-driven changes in the range of minutes to days. Even in the range of milliseconds, the composition and topology of ion channels are not static but engage in highly dynamic processes including stochastic or activity-dependent transient association of the pore-forming and auxiliary subunits, lateral diffusion, as well as clustering of different channels. In this review we briefly discuss the potential impact of mobile sodium, calcium and potassium ion channels and the functional significance of this for individual neurons and neuronal networks. PMID:26891382

Electrical and Optical Characteristics of Undoped and Se-Doped Bi2S3 Transistors

NASA Astrophysics Data System (ADS)

Kilcoyne, Colin; Alsaqqa, Ali; Rahman, Ajara A.; Whittaker-Brooks, Luisa; Sambandamurthy, G.

Semiconducting chalcogenides have been drawing increased attention due to their interesting physical properties, especially in low dimensional structures. Bi2S3 has demonstrated a high optical absorption coefficient, a large bulk mobility, small bandgap, high Seebeck coefficient, and low thermal conductivity. These properties make it a good candidate for optical, electric and thermoelectric applications. However, control over the electrical properties for enhanced thermoelectric performance and optical applications is desired. We present electrical transport and optical properties from individual nanowire and few-layer transistors of single crystalline undoped and Se-doped Bi2S3-xSex. All devices exhibit n-type semiconducting behavior and the ON/OFF ratio, mobility, and conductivity noise behavior are studied as functions of dopant concentration, temperature, and charge carrier density in different conduction regimes. The roles of dopant driven scattering mechanisms and mobility/carrier density fluctuations will be discussed. The potential for this series of materials as optical and electrical switches will be presented. NSF DMR.

Review of temperature dependence of thermal properties, dielectric properties, and perfusion of biological tissues at hyperthermic and ablation temperatures.

PubMed

Rossmanna, Christian; Haemmerich, Dieter

2014-01-01

The application of supraphysiological temperatures (>40°C) to biological tissues causes changes at the molecular, cellular, and structural level, with corresponding changes in tissue function and in thermal, mechanical and dielectric tissue properties. This is particularly relevant for image-guided thermal treatments (e.g. hyperthermia and thermal ablation) delivering heat via focused ultrasound (FUS), radiofrequency (RF), microwave (MW), or laser energy; temperature induced changes in tissue properties are of relevance in relation to predicting tissue temperature profile, monitoring during treatment, and evaluation of treatment results. This paper presents a literature survey of temperature dependence of electrical (electrical conductivity, resistivity, permittivity) and thermal tissue properties (thermal conductivity, specific heat, diffusivity). Data of soft tissues (liver, prostate, muscle, kidney, uterus, collagen, myocardium and spleen) for temperatures between 5 to 90°C, and dielectric properties in the frequency range between 460 kHz and 3 GHz are reported. Furthermore, perfusion changes in tumors including carcinomas, sarcomas, rhabdomyosarcoma, adenocarcinoma and ependymoblastoma in response to hyperthmic temperatures up to 46°C are presented. Where appropriate, mathematical models to describe temperature dependence of properties are presented. The presented data is valuable for mathematical models that predict tissue temperature during thermal therapies (e.g. hyperthermia or thermal ablation), as well as for applications related to prediction and monitoring of temperature induced tissue changes.

Review of temperature dependence of thermal properties, dielectric properties, and perfusion of biological tissues at hyperthermic and ablation temperatures

PubMed Central

Rossmann, Christian; Haemmerich, Dieter

2016-01-01

The application of supraphysiological temperatures (>40°C) to biological tissues causes changes at the molecular, cellular, and structural level, with corresponding changes in tissue function and in thermal, mechanical and dielectric tissue properties. This is particularly relevant for image-guided thermal treatments (e.g. hyperthermia and thermal ablation) delivering heat via focused ultrasound (FUS), radiofrequency (RF), microwave (MW), or laser energy; temperature induced changes in tissue properties are of relevance in relation to predicting tissue temperature profile, monitoring during treatment, and evaluation of treatment results. This paper presents a literature survey of temperature dependence of electrical (electrical conductivity, resistivity, permittivity) and thermal tissue properties (thermal conductivity, specific heat, diffusivity). Data of soft tissues (liver, prostate, muscle, kidney, uterus, collagen, myocardium and spleen) for temperatures between 5 to 90°C, and dielectric properties in the frequency range between 460 kHz and 3 GHz are reported. Furthermore, perfusion changes in tumors including carcinomas, sarcomas, rhabdomyosarcoma, adenocarcinoma and ependymoblastoma in response to hyperthmic temperatures up to 46°C are presented. Where appropriate, mathematical models to describe temperature dependence of properties are presented. The presented data is valuable for mathematical models that predict tissue temperature during thermal therapies (e.g. hyperthermia or thermal ablation), as well as for applications related to prediction and monitoring of temperature induced tissue changes. PMID:25955712

Enhanced electrical properties in solution-processed InGaZnO thin-film transistors by viable hydroxyl group transfer process

NASA Astrophysics Data System (ADS)

Kim, Do-Kyung; Jeong, Hyeon-Seok; Kwon, Hyeok Bin; Kim, Young-Rae; Kang, Shin-Won; Bae, Jin-Hyuk

2018-05-01

We propose a simple hydroxyl group transfer method to improve the electrical characteristics of solution-processed amorphous InGaZnO (IGZO) thin-film transistors (TFTs). Tuned poly(dimethylsiloxane) elastomer, which has a hydroxyl group as a terminal chemical group, was adhered temporarily to an IGZO thin-film during the solidification step to transfer and supply sufficient hydroxyl groups to the IGZO thin-film. The transferred hydroxyl groups led to efficient hydrolysis and condensation reactions, resulting in a denser metal–oxygen–metal network being achieved in the IGZO thin-film compared to the conventional IGZO thin-film. In addition, it was confirmed that there was no morphological deformation, including to the film thickness and surface roughness. The hydroxyl group transferred IGZO based TFTs exhibited enhanced electrical properties (field-effect mobility of 2.21 cm2 V‑1 s‑1, and on/off current ratio of 106) compared to conventional IGZO TFTs (field-effect mobility of 0.73 cm2 V‑1 s‑1 and on/off current ratio of 105).

Laser surface modification of electrically conductive fabrics: Material performance improvement and design effects

NASA Astrophysics Data System (ADS)

Tunakova, Veronika; Hrubosova, Zuzana; Tunak, Maros; Kasparova, Marie; Mullerova, Jana

2018-01-01

Development of lightweight flexible materials for electromagnetic interference shielding has obtained increased attention in recent years particularly for clothing, textiles in-house use and technical applications especially in areas of aircraft, aerospace, automobiles and flexible electronics such as portable electronics and wearable devices. There are many references in the literature concerning development and investigation of electromagnetic shielding lightweight flexible materials especially textile based with different electrically conductive additives. However, only little attention is paid to designing and enhancing the properties of these special fabrics by textile finishing processes. Laser technology applied as a physical treatment method is becoming very popular and can be used in different applications to make improvement and even overcome drawbacks of some of the traditional processes. The main purpose of this study is firstly to analyze the possibilities of transferring design onto the surface of electrically conductive fabrics by laser beam and secondly to study of effect of surface modification degree on performance of conductive fabric including electromagnetic shielding ability and mechanical properties. Woven fabric made of yarns containing 10% of extremely thin stainless steel fiber was used as a conductive substrate.

Alternating current breakdown voltage of ice electret

NASA Astrophysics Data System (ADS)

Oshika, Y.; Tsuchiya, Y.; Okumura, T.; Muramoto, Y.

2017-09-01

Ice has low environmental impact. Our research objectives are to study the availability of ice as a dielectric insulating material at cryogenic temperatures. We focus on ferroelectric ice (iceXI) at cryogenic temperatures. The properties of iceXI, including its formation, are not clear. We attempted to obtain the polarized ice that was similar to iceXI under the applied voltage and cooling to 77 K. The polarized ice have a wide range of engineering applications as electronic materials at cryogenic temperatures. This polarized ice is called ice electret. The structural difference between ice electret and normal ice is only the positions of protons. The effects of the proton arrangement on the breakdown voltage of ice electret were shown because electrical properties are influenced by the structure of ice. We observed an alternating current (ac) breakdown voltage of ice electret and normal ice at 77 K. The mean and minimum ac breakdown voltage values of ice electret were higher than those of normal ice. We considered that the electrically weak part of the normal ice was improved by applied a direct electric field.

Theoretical relationship between elastic wave velocity and electrical resistivity

NASA Astrophysics Data System (ADS)

Lee, Jong-Sub; Yoon, Hyung-Koo

2015-05-01

Elastic wave velocity and electrical resistivity have been commonly applied to estimate stratum structures and obtain subsurface soil design parameters. Both elastic wave velocity and electrical resistivity are related to the void ratio; the objective of this study is therefore to suggest a theoretical relationship between the two physical parameters. Gassmann theory and Archie's equation are applied to propose a new theoretical equation, which relates the compressional wave velocity to shear wave velocity and electrical resistivity. The piezo disk element (PDE) and bender element (BE) are used to measure the compressional and shear wave velocities, respectively. In addition, the electrical resistivity is obtained by using the electrical resistivity probe (ERP). The elastic wave velocity and electrical resistivity are recorded in several types of soils including sand, silty sand, silty clay, silt, and clay-sand mixture. The appropriate input parameters are determined based on the error norm in order to increase the reliability of the proposed relationship. The predicted compressional wave velocities from the shear wave velocity and electrical resistivity are similar to the measured compressional velocities. This study demonstrates that the new theoretical relationship may be effectively used to predict the unknown geophysical property from the measured values.

Electrical properties of PMMA ion-implanted with low-energy Si+ beam

NASA Astrophysics Data System (ADS)

Hadjichristov, G. B.; Gueorguiev, V. K.; Ivanov, Tz E.; Marinov, Y. G.; Ivanov, V. G.; Faulques, E.

2010-01-01

The electrical properties of polymethylmethacrylate (PMMA) after implantation with silicon ions accelerated to an energy of 50 keV are studied under DC electric bias field. The electrical response of the formed material is examined as a function of Si+ fluence in the range 1014 - 1017 cm-2. The carbonaceous subsurface region of the Si+-implanted PMMA displays a significant DC conductivity and a sizable field effect that can be used for electronic applications.

Model for interface formation and the resulting electrical properties for barium-strontium-titanate films on silicon

NASA Astrophysics Data System (ADS)

Mueller, A. H.; Suvorova, N. A.; Irene, E. A.; Auciello, O.; Schultz, J. A.

2003-04-01

The interface formation between sputtered barium strontium titanate (BST) films and both Si and SiO2 substrate surfaces has been followed using real-time spectroscopic ellipsometry and the mass spectrometry of recoiled ions. In both substrates an intermixed interface layer was observed and subcutaneous Si oxidation occurred. A model for the interface formation is proposed in which the interface includes an SiO2 film on Si, and an intermixed film on which is pure BST. During the deposition of BST the interfaces films were observed to change in time. Electrical characterization of the resulting metal-BST interface capacitors indicates that those samples with SiO2 on the Si surface had the best electrical characteristics.

All electrical propagating spin wave spectroscopy with broadband wavevector capability

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

Ciubotaru, F., E-mail: Florin.Ciubotaru@imec.be; KU Leuven, Departement Electrotechniek; Devolder, T.

2016-07-04

We developed an all electrical experiment to perform the broadband phase-resolved spectroscopy of propagating spin waves in micrometer sized thin magnetic stripes. The magnetostatic surface spin waves are excited and detected by scaled down to 125 nm wide inductive antennas, which award ultra broadband wavevector capability. The wavevector selection can be done by applying an excitation frequency above the ferromagnetic resonance. Wavevector demultiplexing is done at the spin wave detector thanks to the rotation of the spin wave phase upon propagation. A simple model accounts for the main features of the apparatus transfer functions. Our approach opens an avenue for themore » all electrical study of wavevector-dependent spin wave properties including dispersion spectra or non-reciprocal propagation.« less

Characterization and properties of micro- and nanowires of controlled size, composition, and geometry fabricated by electrodeposition and ion-track technology

PubMed Central

2012-01-01

Summary The combination of electrodeposition and polymeric templates created by heavy-ion irradiation followed by chemical track etching provides a large variety of poly- and single-crystalline nanowires of controlled size, geometry, composition, and surface morphology. Recent results obtained by our group on the fabrication, characterization and size-dependent properties of nanowires synthesized by this technique are reviewed, including investigations on electrical resistivity, surface plasmon resonances, and thermal instability. PMID:23365800

Chemistry Lab for Phoenix Mars Lander

NASA Technical Reports Server (NTRS)

2007-01-01

The science payload of NASA's Phoenix Mars Lander includes a multi-tool instrument named the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA). The instrument's wet chemistry laboratory, prominent in this photograph, will measure a range of chemical properties of Martian soil samples, such as the presence of dissolved salts and the level of acidity or alkalinity. Other tools that are parts of the instrument are microscopes that will examine samples' mineral grains and a probe that will check the soil's thermal and electrical properties.

Unique properties of halide perovskites as possible origins of the superior solar cell performance.

PubMed

Yin, Wan-Jian; Shi, Tingting; Yan, Yanfa

2014-07-16

Halide perovskites solar cells have the potential to exhibit higher energy conversion efficiencies with ultrathin films than conventional thin-film solar cells based on CdTe, CuInSe2 , and Cu2 ZnSnSe4 . The superior solar-cell performance of halide perovskites may originate from its high optical absorption, comparable electron and hole effective mass, and electrically clean defect properties, including point defects and grain boundaries. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Driscoll, S.B.; Walton, T.C.

Polyimides have gained wide acceptance for use in many aerospace composite, electrical, and industrial applications. The intent of this work is to share with the reader practical knowledge of how some of the currently available commercial systems perform. Several prepreg processable polyimide systems were evaluated for adhesive properties and characterized with the use of SEM, TGA, DSC, TMA, Dynamic Spectroscopy, and Force vs. Time Electronic Impact Analyses for comparison. The chemistry and nature of these resin systems is reviewed, including several BMIs (new hot melts examined)., Amide-Imides (Al) and Thermoplastic Polyimide (TPI). PMR-15 and a high temperature epoxy resin aremore » included for comparison of high temperature properties. 17 references.« less

Characterization of Soil Heterogeneity Across Scales in an Intensively Investigated Soil Volume

NASA Astrophysics Data System (ADS)

Patterson, Matthew; Gimenez, Daniel; Nemes, Attila; Dathe, Annette; French, Helen; Bloem, Esther; Koestel, John; Jarvis, Nick

2016-04-01

Heterogeneous water flow in undisturbed soils is a natural occurrence that is complex to model due to potential changes in hydraulic properties in soils over changes in space. The use of geophysical methods, such as Electrical Resistivity Tomography (ERT), can provide a minimally-invasive approximation of the spatial heterogeneity of the soil. This spatial distribution can then be combined with measured hydraulic properties to inform a model. An experiment was conducted on an Intensively Investigated Soil Volume (IISV), with dimensions of 2m x 1m x 0.8m, located in an agricultural field that is part of the Gryteland catchment in Ås, Norway. The location of the IISV was determined through surface ERT runs at two sequential resolutions. The first run was used to find an area of higher apparent electrical resistivity in a 23.5 x 11.5 m area with 0.5 m spacing. The second run measured apparent electrical resistivity in a 4.7 x 1 m area with 0.1 m spacing, from which the final IISV volume was derived. Distinct features found in the higher resolution run of the IISV, including a recent tire track from a harvester, were used as a spatial reference point for the installation of 20 pairs of TDR probes and tensiometers. The instruments measured water content, temperature and pressure potential at 10 minute intervals and ran continuously for a period of two weeks. After completion of the data collection the IISV was intensively sampled, with 30 samples taken for bulk density, 62 for hydraulic property measurements, and 20 to be used for both CT scanning and hydraulic property measurements. The measurement of hydraulic properties is ongoing and retention will be measured in the 0 - 100 cm range on a sand table, and from 100 - approx. 900 cm with an automated evaporation method. The formation of spatial clusters to represent the soil heterogeneity as relatively homogeneous units based on mesoscale properties like apparent electrical resistivity, bulk density, texture, in-situ measurements and image-derived properties at the microscale will be presented and discussed. Work combining the spatial clusters with estimated and measured hydraulic properties to inform the HYDRUS 3D model will also be discussed.

Incorporation of polydimethylsiloxane with reduced graphene oxide and zinc oxide for tensile and electrical properties

NASA Astrophysics Data System (ADS)

Danial, N. S.; Ramli, Muhammad. M.; Halin, D. S. C.; Hong, H. C.; Isa, S. Salwa M.; Abdullah, M. M. A. B.; Anhar, N. A. M.; Talip, L. F. A.; Mazlan, N. S.

2017-09-01

Polydimethylsiloxane (PDMS) is an organosilicon polymer that is commonly used to incorporate with other fillers. PDMS in high viscous liquid form is mechanically stirred with reduced graphene oxide (rGO) and mixed with zinc oxide (ZnO) with specific ratio, thus rendering into two types of samples. The mechanical and electrical properties of both samples are characterized. The result shows that PDMS sample with 50 mg rGO has the highest tensile strength with the value of 9.1 MPa. For electrical properties, sample with the lowest resistance is PDMS with 50 mg rGO and ZnO with the value of l.67×l05 Ω. This experiment shows the significant role of conductive fillers like rGO and ZnO incorporated in polymeric material such as PDMS to improve its electrical properties.

Topological defects in electric double layers of ionic liquids at carbon interfaces

DOE PAGES

Black, Jennifer M.; Okatan, Mahmut Baris; Feng, Guang; ...

2015-06-07

The structure and properties of the electrical double layer in ionic liquids is of interest in a wide range of areas including energy storage, catalysis, lubrication, and many more. Theories describing the electrical double layer for ionic liquids have been proposed, however a full molecular level description of the double layer is lacking. To date, studies have been predominantly focused on ion distributions normal to the surface, however the 3D nature of the electrical double layer in ionic liquids requires a full picture of the double layer structure not only normal to the surface, but also in plane. Here wemore » utilize 3D force mapping to probe the in plane structure of an ionic liquid at a graphite interface and report the direct observation of the structure and properties of topological defects. The observation of ion layering at structural defects such as step-edges, reinforced by molecular dynamics simulations, defines the spatial resolution of the method. Observation of defects allows for the establishment of the universality of ionic liquid behavior vs. separation from the carbon surface and to map internal defect structure. In conclusion, these studies offer a universal pathway for probing the internal structure of topological defects in soft condensed matter on the nanometer level in three dimensions.« less

Theoretical models for electrochemical impedance spectroscopy and local ζ-potential of unfolded proteins in nanopores

NASA Astrophysics Data System (ADS)

Vitarelli, Michael J.; Talaga, David S.

2013-09-01

Single solid-state nanopores find increasing use for electrical detection and/or manipulation of macromolecules. These applications exploit the changes in signals due to the geometry and electrical properties of the molecular species found within the nanopore. The sensitivity and resolution of such measurements are also influenced by the geometric and electrical properties of the nanopore. This paper continues the development of an analytical theory to predict the electrochemical impedance spectra of nanopores by including the influence of the presence of an unfolded protein using the variable topology finite Warburg impedance model previously published by the authors. The local excluded volume of, and charges present on, the segment of protein sampled by the nanopore are shown to influence the shape and peak frequency of the electrochemical impedance spectrum. An analytical theory is used to relate the capacitive response of the electrical double layer at the surface of the protein to both the charge density at the protein surface and the more commonly measured zeta potential. Illustrative examples show how the theory predicts that the varying sequential regions of surface charge density and excluded volume dictated by the protein primary structure may allow for an impedance-based approach to identifying unfolded proteins.

Effects of preparation steps on the physical parameters and electromechanical properties of IPMC actuators

NASA Astrophysics Data System (ADS)

Wang, Yanjie; Zhu, Zicai; Chen, Hualing; Luo, Bin; Chang, Longfei; Wang, Yongquan; Li, Dichen

2014-12-01

The electromechanical properties of ionic polymer-metal composites (IPMC) are affected by many factors, including resistivity of surface electrodes, bending stiffness and dielectric modulus, etc, which are closely related to physical and chemical preparation steps. This paper focuses on the effects of preparation steps on these physical parameters and electromechanical properties of IPMC actuators. The mechanisms of electrode formation in the preparation steps are also clarified and investigated. To obtain samples with different features, one or more of the crucial process steps, including pretreatment, impregnation-reduction and chemical plating, were selected to fabricate IPMC. The experimental observations revealed that the physical parameters of IPMC strongly depend on their electrode morphologies caused by different steps, which were reasonable from the standpoint of physics. IPMC with the characteristics of low surface resistance and low bending stiffness, and a large area of interface electrode exhibits a perfect performance. The improvements were considered to be attributed to the double-layer electrostatic effect, induced by the broad dispersion of penetrated electrode nanoparticles. An electrical component, consisting of an equivalent circuit of a parallel combination of the serial circuit of the resistance and the electric double-layer capacitance, is introduced to qualitatively explain the deformation behaviors of IPMC. This research helps to improve the preparation steps and promote the understanding of IPMC.

Double-edged effect of electric field on the mechanical property of water-filled carbon nanotubes with an application to nanoscale trigger.

PubMed

Ye, Hongfei; Zheng, Yonggang; Zhou, Lili; Zhao, Junfei; Zhang, Hong Wu; Chen, Zhen

2017-11-08

Polar water molecules would exhibit extraordinary phenomena under nanoscale confinement. By means of electric field, the water-filled carbon nanotube (CNT) that has been successfully fabricated in laboratory is expected to make distinct responses to the external electricity. Here, we examine the effect of electric field direction on the mechanical property of water-filled CNTs. It is found that the longitudinal electric field enhances but the transversal electric field reduces the elastic modulus and critical buckling stress of water-filled CNTs. The double-edged effect of electric field is attributed to the competition between the axial and circumferential pressures induced by polar water molecules. Furthermore, it is notable that the transversal electric field could result in an internal pressure with elliptical distribution, which is an effective and convenient approach to apply the nonuniform pressure on nanochannels. Based on a pre-strained water-filled CNTs, we design a nanoscale trigger with the evident and rapid height change started through switching the direction of electric field. The reported finding lays a foundation for the electricity-controlled property of nanochannels filled with polar molecules and provides an insight into the design of nanoscale functional devices. © 2017 IOP Publishing Ltd.

Organic light-emitting diodes from homoleptic square planar complexes

DOEpatents

Omary, Mohammad A

2013-11-12

Homoleptic square planar complexes [M(N.LAMBDA.N).sub.2], wherein two identical N.LAMBDA.N bidentate anionic ligands are coordinated to the M(II) metal center, including bidentate square planar complexes of triazolates, possess optical and electrical properties that make them useful for a wide variety of optical and electrical devices and applications. In particular, the complexes are useful for obtaining white or monochromatic organic light-emitting diodes ("OLEDs"). Improved white organic light emitting diode ("WOLED") designs have improved efficacy and/or color stability at high brightness in single- or two-emitter white or monochrome OLEDs that utilize homoleptic square planar complexes, including bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) ("Pt(ptp).sub.2").

Method for making defect-free zone by laser-annealing of doped silicon

DOEpatents

Narayan, Jagdish; White, Clark W.; Young, Rosa T.

1980-01-01

This invention is a method for improving the electrical properties of silicon semiconductor material. The method comprises irradiating a selected surface layer of the semiconductor material with high-power laser pulses characterized by a special combination of wavelength, energy level, and duration. The combination effects melting of the layer without degrading electrical properties, such as minority-carrier diffusion length. The method is applicable to improving the electrical properties of n- and p-type silicon which is to be doped to form an electrical junction therein. Another important application of the method is the virtually complete removal of doping-induced defects from ion-implanted or diffusion-doped silicon substrates.

Tailoring Functional Chitosan-based Composites for Food Applications.

PubMed

Nunes, Cláudia; Coimbra, Manuel A; Ferreira, Paula

2018-03-08

Chitosan-based functional materials are emerging for food applications. The covalent bonding of molecular entities demonstrates to enhance resistance to the typical acidity of food assigning mechanical and moisture/gas barrier properties. Moreover, the grafting to chitosan of some functional molecules, like phenolic compounds or essential oils, gives antioxidant, antimicrobial, among others properties to chitosan. The addition of nanofillers to chitosan and other biopolymers improves the already mentioned required properties for food applications and can attribute electrical conductivity and magnetic properties for active and intelligent packaging. Electrical conductivity is a required property for the processing of food at low temperature using electric fields or for sensors application. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Monitoring electrical properties for improving the lithological and hydrological characterization of landslides

NASA Astrophysics Data System (ADS)

Malet, J. P.; Gance, J.; Lajaunie, M.; Gallistl, J.; Denchik, N.; Flores Orozco, A.; Ottowitz, D.; Supper, R.; Sailhac, P.; Gautier, S.; Schmutz, M.

2017-12-01

Imaging water flows in landslides is of critical importance as the distribution of pore-fluid pressures controls the dynamics (acceleration, deceleration) of the material. Detecting and imaging water is a difficult task, not only because of the complex topography and the small dimensions of the geological structures, but also because the landslide material consists of unsaturated porous and heterogeneous fractured media, leading to multi-scale water-flow properties. Further, these properties can change in time, in relation to temperature, rainfall and biological forcings. Electrical properties are relevant proxies of the sub-surface hydrological properties. In order to image water in landslide bodies, we propose to combine multi-frequency electrical and electromagnetic measurements using campaigns or permanent instruments, and surface/boreole investigations, installed on several unstable slopes in France. To evaluate the information gained from electrical properties for different geological conditions, we discuss electrical and electro-magnetic imaging results for data collected at four different landslides located in France (Super-Sauze and La Valette in the South East Alps, Lodève lin the southern border of the Massif Central Massif, and Séchilienne in the North French Alps). Time-lapse electrical DC resistivity observations, complex electrical conductivity (conduction and polarization/chargeability) measured by IP imaging methods, and controlled-source electromagnetic (CS-AMT) methods are discussed. Imaging results demonstrate an improved lithological characterization of the landslide structures (delineation of the sliding planes, identification of the fractures, discrimination of clay lenses with enhanced resolution); further, water infiltration within the soil matrix and/or the fractures is discriminated allowing better modelling of the hydrological regime of the landslides at the slope scale. This research is conducted in the frame of the project HYDROSLIDE - Hydrogeophysical Monitoring of Clay-Rich Landslides funded by the Austrian Science Fund (FWF) and the French Research Agency (ANR).

The Characterization of Grade PCEA Recycle Graphite Pilot Scale Billets

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

Burchell, Timothy D; Pappano, Peter J

2010-10-01

Here we report the physical properties of a series specimens machined from pilot scale (~ 152 mm diameter x ~305 mm length) grade PCEA recycle billets manufactured by GrafTech. The pilot scale billets were processed with increasing amounts of (unirradiated) graphite (from 20% to 100%) introduced to the formulation with the goal of determining if large fractions of recycle graphite have a deleterious effect on properties. The properties determined include Bulk Density, Electrical Resistivity, Elastic (Young s) Modulus, and Coefficient of Thermal Expansion. Although property variations were observed to be correlated with the recycle fraction, the magnitude of the variationsmore » was noted to be small.« less

Manipulation of local optical properties and structures in molybdenum-disulfide monolayers using electric field-assisted near-field techniques.

PubMed

Nozaki, Junji; Fukumura, Musashi; Aoki, Takaaki; Maniwa, Yutaka; Yomogida, Yohei; Yanagi, Kazuhiro

2017-04-05

Remarkable optical properties, such as quantum light emission and large optical nonlinearity, have been observed in peculiar local sites of transition metal dichalcogenide monolayers, and the ability to tune such properties is of great importance for their optoelectronic applications. For that purpose, it is crucial to elucidate and tune their local optical properties simultaneously. Here, we develop an electric field-assisted near-field technique. Using this technique we can clarify and tune the local optical properties simultaneously with a spatial resolution of approximately 100 nm due to the electric field from the cantilever. The photoluminescence at local sites in molybdenum-disulfide (MoS 2 ) monolayers is reversibly modulated, and the inhomogeneity of the charge neutral points and quantum yields is suggested. We successfully etch MoS 2 crystals and fabricate nanoribbons using near-field techniques in combination with an electric field. This study creates a way to tune the local optical properties and to freely design the structural shapes of atomic monolayers using near-field optics.

Improvisation of mechanical and electrical properties of Cu by reinforcing MWCNT using modified electro-co-deposition process

NASA Astrophysics Data System (ADS)

Belgamwar, Sachin U.; Sharma, N. N.

2018-04-01

Multi-walled Carbon nanotubes–copper (MWCNT/Cu) composite powders with variable MWCNT content were synthesized by modified electro-co-deposition method. The electro-co-deposited MWCNT/Cu powders were consolidated by conventional compaction and sintering process. The consolidated products were then hot rolled and cold drawn to fine wires. The MWCNT/Cu composite wire samples were characterized for electrical and mechanical properties. We have been able to achieve an increase of around 8% in electrical conductivity of the form wires repeatedly. It has been observed that there was gradual improvement in the properties with reinforcement of MWCNT in the copper matrix. The betterment of electrical property has been achieved with simultaneous improvement in mechanical properties of the wire. The yield strength of MWCNT/Cu composite wire was found to be four times and the tensile strength two times greater than that of pure copper. The improved properties are attributed to the proper distribution of MWCNTs in the copper matrix and excellent interfacial bonding between MWCNT and composite copper fabricated by the modified method.

Electronic properties of BN-doped bilayer graphene and graphyne in the presence of electric field

NASA Astrophysics Data System (ADS)

Majidi, R.; Karami, A. R.

2013-11-01

In the present paper, we have used density functional theory to study electronic properties of bilayer graphene and graphyne doped with B and N impurities in the presence of electric field. It has been demonstrated that a band gap is opened in the band structures of the bilayer graphene and graphyne by B and N doping. We have also investigated influence of electric field on the electronic properties of BN-doped bilayer graphene and graphyne. It is found that the band gaps induced by B and N impurities are increased by applying electric field. Our results reveal that doping with B and N, and applying electric field are an effective method to open and control a band gap which is useful to design carbon-based next-generation electronic devices.

Methylammonium lead iodide grain boundaries exhibit depth-dependent electrical properties

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

MacDonald, Gordon A.; Yang, Mengjin; Berweger, Samuel

In this paper, the nanoscale through-film and lateral photo-response and conductivity of large-grained methylammonium lead iodide (MAPbI 3) thin films are studied. In perovskite solar cells (PSC), these films result in efficiencies >17%. The grain boundaries (GBs) show high resistance at the top surface of the film, and act as an impediment to photocurrent collection. However, lower resistance pathways between grains exist below the top surface of the film, indicating that there exists a depth-dependent resistance of GBs (R GB(z)). Furthermore, lateral conductivity measurements indicate that R GB(z) exhibits GB-to-GB heterogeneity. These results indicate that increased photocurrent collection along GBsmore » is not a prerequisite for high-efficiency PSCs. Rather, better control of depth-dependent GB electrical properties, and an improvement in the homogeneity of the GB-to-GB electrical properties, must be managed to enable further improvements in PSC efficiency. Finally, these results refute the implicit assumption seen in the literature that the electrical properties of GBs, as measured at the top surface of the perovskite film, necessarily reflect the electrical properties of GBs within the thickness of the film.« less

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.

Methylammonium lead iodide grain boundaries exhibit depth-dependent electrical properties

DOE PAGES

MacDonald, Gordon A.; Yang, Mengjin; Berweger, Samuel; ...

2016-09-23

In this paper, the nanoscale through-film and lateral photo-response and conductivity of large-grained methylammonium lead iodide (MAPbI 3) thin films are studied. In perovskite solar cells (PSC), these films result in efficiencies >17%. The grain boundaries (GBs) show high resistance at the top surface of the film, and act as an impediment to photocurrent collection. However, lower resistance pathways between grains exist below the top surface of the film, indicating that there exists a depth-dependent resistance of GBs (R GB(z)). Furthermore, lateral conductivity measurements indicate that R GB(z) exhibits GB-to-GB heterogeneity. These results indicate that increased photocurrent collection along GBsmore » is not a prerequisite for high-efficiency PSCs. Rather, better control of depth-dependent GB electrical properties, and an improvement in the homogeneity of the GB-to-GB electrical properties, must be managed to enable further improvements in PSC efficiency. Finally, these results refute the implicit assumption seen in the literature that the electrical properties of GBs, as measured at the top surface of the perovskite film, necessarily reflect the electrical properties of GBs within the thickness of the film.« less

A mechanical characterisation on multiple timescales of electroconductive magnetorheological elastomers

NASA Astrophysics Data System (ADS)

Schümann, M.; Morich, J.; Kaufhold, T.; Böhm, V.; Zimmermann, K.; Odenbach, S.

2018-05-01

Magnetorheological elastomers are a type of smart hybrid material which combines elastic properties of a soft elastomer matrix with magnetic properties of magnetic micro particles. This leads to a material with magnetically controllable mechanical properties of which the magnetorheological effect is the best known. The addition of electroconductive particles to the polymer mix adds electrical properties to the material behaviour. The resulting electrical resistance of the sample can be manipulated by external magnetic fields and mechanical loads. This results in a distinct interplay of mechanical, electrical and magnetic effects with a highly complex time behaviour. In this paper a mechanical characterisation on multiple time scales was conducted to get an insight on the short and long-term electrical and mechanical behaviour of this novel material. The results show a complex resistivity behaviour on several timescales, sensitive to magnetic fields and strain velocity. The observed material exhibits fatigue and relaxation behaviour, whereas the magnetorheological effect appears not to interfere with the piezoresistive properties.

Electrical properties of undoped zinc oxide nanostructures at different annealing temperature

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

Nasir, M. F., E-mail: babaibaik2002@yahoo.com; Zainol, M. N., E-mail: nizarzainol@yahoo.com; Hannas, M., E-mail: mhannas@gmail.com

This project has been focused on the electrical and optical properties respectively on the effect of Undoped zinc oxide (ZnO) thin films at different annealing temperature which is varied 400 °C, 450 °C, 500 °C, and 550 °C.Undoped ZnO solutions were deposited onto the glass substrates using sol-gel spin coating method. This project was involved with three phases, which are thin films preparation, deposition and characterization. The thin films were characterized using Current Voltage (I-V) measurement and UV-vis-NIR spectrophotometer for electrical properties and optical properties. The electrical properties show that the resistivity is the lowest at 500 °C which itsmore » resistivity is 5.36 × 10{sup 4} Ωcm{sup −1}. The absorption coefficient spectrum obtained from UV-Vis-NIR spectrophotometer measurement shows all films exhibit very low absorption in the visible (400-800 nm) and near infrared (NIR) (>800 nm) range but exhibit high absorption in the UV range.« less

Electrical properties of Mg doped ZnO nanostructure annealed at different temperature

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

Mohamed, R., E-mail: ruziana12@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Rusop, M., E-mail: nanouitm@gmail.com

In this work, ZincOxide (ZnO) nanostructures doped with Mg were successfully grown on the glass substrate. Magnesium (Mg) metal element was added in the ZnO host which acts as a doping agent. Different temperature in range of 250°C to 500°C was used in order to investigate the effect of annealing temperature of ZnO thin films. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate the physical characteristic of ZnO thin films. FESEM results have revealed that ZnO nanorods were grown vertically aligned. The structural properties were determined by using X-Ray Diffraction (XRD) analysis. XRD results showed Mg doped ZnOmore » thin have highest crystalinnity at 500°C annealing temperature. The electrical properties were investigating by using Current-Voltage (I-V) measurement. I-V measurement showed the electrical properties were varied at different annealing temperature. The annealing temperature at 500°C has the highest electrical conductance properties.« less

Electric field induced optical gain of a hydrogenic impurity in a Cd{sub 0.8}Zn{sub 0.2}Se/ZnSe parabolic quantum dot

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

Jasmine, P. Christina Lily; Peter, A. John, E-mail: a.john.peter@gmail.com

The dependence of electric field on the electronic and optical properties is investigated in a Cd{sub 0.8}Zn{sub 0.2}Se/ZnSe quantum dot. The hydrogenic binding energy, in the presence of electric field, is calculated with the spatial confinement effect. The electric field dependent optical gain with the photon energy is found using compact density matrix method. The results show that the electric field has a great influence on the optical properties of II-VI semiconductor quantum dot.

Electrical and optical performance of transparent conducting oxide films deposited by electrostatic spray assisted vapour deposition.

PubMed

Hou, Xianghui; Choy, Kwang-Leong; Liu, Jun-Peng

2011-09-01

Transparent conducting oxide (TCO) films have the remarkable combination of high electrical conductivity and optical transparency. There is always a strong motivation to produce TCO films with good performance at low cost. Electrostatic Spray Assisted Vapor Deposition (ESAVD), as a variant of chemical vapour deposition (CVD), is a non-vacuum and low-cost deposition method. Several types of TCO films have been deposited using ESAVD process, including indium tin oxide (ITO), antimony-doped tin oxide (ATO), and fluorine doped tin oxide (FTO). This paper reports the electrical and optical properties of TCO films produced by ESAVD methods, as well as the effects of post treatment by plasma hydrogenation on these TCO films. The possible mechanisms involved during plasma hydrogenation of TCO films are also discussed. Reduction and etching effect during plasma hydrogenation are the most important factors which determine the optical and electrical performance of TCO films.

Plasma Plume Characterization of the HERMeS during a 1722-hr Wear Test Campaign

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Williams, George J.; Peterson, Peter Y.; Kamhawi, Hani; Gilland, James H.; Herman, Daniel A.

2017-01-01

A 1722-hour wear test campaign of NASAs 12.5 kilowatt Hall Effect Rocket with Magnetic Shielding was completed. This wear test campaign, completed in 2016, was divided into four segments including an electrical configuration characterization test, two short duration tests, and one long wear test. During the electrical configuration characterization test, the plasma plume was examined to provide data to support the down select of the electrical configuration for further testing. During the long wear tests, the plasma plume was periodically examined for indications of changes in thruster behavior. Examination of the plasma plume data from the electrical configuration characterization test revealed a correlation between the plume properties and the presence of a conduction path through the front poles. Examination of the long wear test plasma plume data revealed that the plume characteristics remained unchanged during testing to within the measurement uncertainty.

Plasma Plume Characterization of the HERMeS During a 1722-hr Wear Test Campaign

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Williams, George J.; Peterson, Peter Y.; Kamhawi, Hani; Gilland, James H.; Herman, Daniel A.

2017-01-01

A 1722-hr wear test campaign of NASA's 12.5-kW Hall Effect Rocket with Magnetic Shielding was completed. This wear test campaign, completed in 2016, was divided into four segments including an electrical configuration characterization test, two short duration tests, and one long wear test. During the electrical configuration characterization test, the plasma plume was examined to provide data to support the down select of the electrical configuration for further testing. During the long wear tests, the plasma plume was periodically examined for indications of changes in thruster behavior. Examination of the plasma plume data from the electrical configuration characterization test revealed a correlation between the plume properties and the presence of a conduction path through the front poles. Examination of the long wear test plasma plume data revealed that the plume characteristics remained unchanged during testing to within the measurement uncertainty.

Feedback linearizing control of a MIMO power system

NASA Astrophysics Data System (ADS)

Ilyes, Laszlo

Prior research has demonstrated that either the mechanical or electrical subsystem of a synchronous electric generator may be controlled using single-input single-output (SISO) nonlinear feedback linearization. This research suggests a new approach which applies nonlinear feedback linearization to a multi-input multi-output (MIMO) model of the synchronous electric generator connected to an infinite bus load model. In this way, the electrical and mechanical subsystems may be linearized and simultaneously decoupled through the introduction of a pair of auxiliary inputs. This allows well known, linear, SISO control methods to be effectively applied to the resulting systems. The derivation of the feedback linearizing control law is presented in detail, including a discussion on the use of symbolic math processing as a development tool. The linearizing and decoupling properties of the control law are validated through simulation. And finally, the robustness of the control law is demonstrated.

Creating and optimizing interfaces for electric-field and photon-induced charge transfer.

PubMed

Park, Byoungnam; Whitham, Kevin; Cho, Jiung; Reichmanis, Elsa

2012-11-27

We create and optimize a structurally well-defined electron donor-acceptor planar heterojunction interface in which electric-field and/or photon-induced charge transfer occurs. Electric-field-induced charge transfer in the dark and exciton dissociation at a pentacene/PCBM interface were probed by in situ thickness-dependent threshold voltage shift measurements in field-effect transistor devices during the formation of the interface. Electric-field-induced charge transfer at the interface in the dark is correlated with development of the pentacene accumulation layer close to PCBM, that is, including interface area, and dielectric relaxation time in PCBM. Further, we demonstrate an in situ test structure that allows probing of both exciton diffusion length and charge transport properties, crucial for optimizing optoelectronic devices. Competition between the optical absorption length and the exciton diffusion length in pentacene governs exciton dissociation at the interface. Charge transfer mechanisms in the dark and under illumination are detailed.

Cryogenic electrical properties of irradiated cyanate ester/epoxy insulation for fusion magnets

NASA Astrophysics Data System (ADS)

Li, X.; Wu, Z. X.; Li, J.; Xu, D.; Liu, H. M.; Huang, R. J.; Li, L. F.

2017-12-01

The insulation materials used in high field fusion magnets require excellent mechanical properties, high electrical breakdown strength, good thermal conductivity and high radiation tolerance. Previous investigations showed that cyanate ester/epoxy (CE/EP) insulation material, a candidate insulation for fusion magnets, can maintain good mechanical performance at cryogenic temperature after 10 MGy irradiation and has a much longer pot life than traditional epoxy insulation material. In order to quantify the electrical properties of the CE/EP insulation material at low temperature, a cryogenic electrical property testing system cooled by a G-M cryocooler was developed for this study. An insulation material with 40% cyanate ester and 60% epoxy was subjected to 60Co γ-ray irradiation in air at ambient temperature with a dose rate of 300 Gy/min, and total doses of 1 MGy, 5 MGy and 10 MGy. The electrical breakdown strength of this CE/EP insulation material was measured before and after irradiation. The results show that cryogenic temperature has a positive effect on the electrical breakdown strength of this composite, while the influence of 60Co γ-ray irradiation is not obvious at 6.1 K.

Structural, optical and electrical properties of copper antimony sulfide thin films grown by a citrate-assisted single chemical bath deposition

NASA Astrophysics Data System (ADS)

Loranca-Ramos, F. E.; Diliegros-Godines, C. J.; Silva González, R.; Pal, Mou

2018-01-01

Copper antimony sulfide (CAS) has been proposed as low toxicity and earth abundant absorber materials for thin film photovoltaics due to their suitable optical band gap, high absorption coefficient and p-type electrical conductivity. The present work reports the formation of copper antimony sulfide by chemical bath deposition using sodium citrate as a complexing agent. We show that by tuning the annealing condition, one can obtain either chalcostibite or tetrahedrite phase. However, the main challenge was co-deposition of copper and antimony as ternary sulfides from a single chemical bath due to the distinct chemical behavior of these metals. The as-deposited films were subjected to several trials of thermal treatment using different temperatures and time to find the optimized annealing condition. The films were characterized by different techniques including Raman spectroscopy, X-ray diffraction (XRD), profilometer, scanning electron microscopy (SEM), UV-vis spectrophotometer, and Hall Effect measurements. The results show that the formation of chalcostibite and tetrahedrite phases is highly sensitive to annealing conditions. The electrical properties obtained for the chalcostibite films varied as the annealing temperature increases from 280 to 350 °C: hole concentration (n) = 1017-1018 cm-3, resistivity (ρ) = 1.74-2.14 Ωcm and carrier mobility (μ) = 4.7-9.26 cm2/Vseg. While for the tetrahedrite films, the electrical properties were n = 5 × 1019 cm-3, μ = 18.24 cm2/Vseg, and ρ = 5.8 × 10-3 Ωcm. A possible mechanism for the formation of ternary copper antimony sulfide has also been proposed.

Electrical conductivity, dielectric response and space charge dynamics of an electroactive polymer with and without nanofiller reinforcement

NASA Astrophysics Data System (ADS)

Kochetov, R.; Tsekmes, I. A.; Morshuis, P. H. F.

2015-07-01

Electroactive polymers have gained considerable attention over the last 20 years for exhibiting a large displacement in response to electrical stimulation. The promising fields of application include wave energy converters, muscle-like actuators, sensors, robotics, and biomimetics. For an electrical engineer, electroactive polymers can be seen as a dielectric elastomer film or a compliant capacitor with a highly deformable elastomeric medium. If the elastomer is pre-stretched and pre-charged, a reduction of the tensile force lets the elastomer revert to its original form and increases the electrical potential. The light weight of electroactive polymers, low cost, high intrinsic breakdown strength, cyclical way of operation, reliable performance, and high efficiency can be exploited to utilize the elastomeric material as a transducer. The energy storage for a linear dielectric polymer is determined by its relative permittivity and the applied electric field. The latter is limited by the dielectric breakdown strength of the material. Therefore, to generate a high energy density of a flexible capacitor, the film must be used at the voltage level close to the material’s breakdown or inorganic particles with high dielectric permittivity which can be introduced into the polymer matrix. In the present study, silicone-titania elastomer nanocomposites were produced and the influence of nanoparticles on the macroscopic dielectric properties of the neat elastomer including space charge dynamics, complex permittivity, and electrical conductivity, were investigated.

Electrical Resistivity Imaging Below Nuclear Waste Tank Farms at the Hanford Site

NASA Astrophysics Data System (ADS)

Rucker, D. F.; Levitt, M. T.

2006-12-01

The Hanford Site, a Department of Energy nuclear processing facility in eastern Washington, contains a complex series of radiological liquid waste disposal and storage facilities. The primary method of interim storage is the use of large single-shelled steel tanks with capacities of up to 3790 m3 (1 million gallons). The tanks are organized below ground into tank farms, with about 12 tanks per farm. The liquid waste within the tanks is primarily comprised of inorganic salts with minor constituents of heavy metals and radiological metals. The electrical properties of the radiological waste are significantly different to that of the surrounding engineered fill and native geologic formations. Over the past 60 years since the earliest tanks have been in use, many have been known to leak. An electrical resistivity survey was conducted within a tank farm to map the extent of the plumes resulting from historic leaks. Traditional surface-based electrical resistivity surveys resulted in unusable data due to the significant subsurface infrastructure that included a network of delivery pipes, wells, fences, and electrical discharge sources . HGI adapted the resistivity technique to include the site infrastructure as transceivers to augment data density and geometry. The results show a distribution of low resistivity values within the farm in areas that match known historic leak sites. The addition of site infrastructure as sensors demonstrates that the electrical resistivity technique can be used in highly industrial sites.

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.

1995-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

Lignin-Based Electrospun Nanofibers Reinforced with Cellulose Nanocrystals

Treesearch

Mariko Ago; Kunihiko Okajima; Joseph E. Jakes; Park Sunkyu; Orlando J. Rojas

2012-01-01

Lignin-based fibers were produced by electrospinning aqueous dispersions of lignin, poly(vinyl alcohol) (PVA), and cellulose nanocrystals (CNCs). Defect-free nanofibers with up to 90 wt % lignin and 15% CNCs were achieved. The properties of the aqueous dispersions, including viscosity, electrical conductivity, and surface tension, were examined and correlated to the...

78 FR 62361 - Union Electric Company (dba Ameren Missouri); Missouri; Taum Sauk Pumped Storage Project; Notice...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-21

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Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-19

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Surface electrical properties experiment study phase, volume 3

NASA Technical Reports Server (NTRS)

1973-01-01

The reliability and quality assurance system and procedures used in developing test equipment for the Lunar Experiment projects are described. The subjects discussed include the following: (1) documentation control, (2) design review, (3) parts and materials selection, (4) material procurement, (5) inspection procedures, (6) qualification and special testing, and failure modes and effects analysis.

Coupled Electro-Hydrodynamic Effects of Electro-Osmosis from Pore Scale to Darcy Scale

NASA Astrophysics Data System (ADS)

Schotting, R.; Joekar-Niasar, V.; Leijnse, A.

2011-12-01

Electro-osmosis is "movement of a fluid under the effect of an electric field in a porous medium". This phenomenon has many applications in civil engineering (slope stabilization, dewatering), environmental engineering (soil remediation, sludge dewatering), chemical engineering (micro- or nano- mixers), medical engineering (drug delivery), etc. The key factor in electro-osmosis is the competition between the electrochemical and hydrodynamic forces as well as the coupling between the solid surface and the electrolyte properties. The objective of this research is to understand the influence of pore-scale heterogeneities of surface properties on the Darcy-scale behavior. We develop novel analytical solutions for the flow and transport of electrolyte including electro-hydrodynamic forces in a single micro-channel. We propose the complete analytical solution for monovalent electrolyte at full range overlapping double layers, and nonlinear electric field, including the Donan effect in transport of ions. These pore-scale formulations are numerically upscaled to obtain the Darcy-scale behavior. Our results show the contribution of electro-osmotic, chemical-osmotic and hydrodynamic components of the flow equation on pressure field evolution and multi-directional flow field at Darcy scale.

Influence of processing history on the mechanical properties and electrical resistivity of polycarbonate - multi-walled carbon nanotubes nanocomposites

NASA Astrophysics Data System (ADS)

Choong, Gabriel Y. H.; De Focatiis, Davide S. A.

2015-05-01

In this work we investigate the effects of compounding temperature and secondary melt processing on the mechanical response and electrical behaviour of polycarbonate filled with 3 wt% carbon nanotubes. The nanocomposites were melt compounded in an industrial setting at a range of temperatures, and subsequently injection moulded or compression moulded. The surface hardness, uniaxial tensile properties and electrical resistivity were measured. Secondary melt processing is found to be the dominant process in determining the final mechanical properties and resistivity of these materials.

The influence of the dispersion method on the electrical properties of vapor-grown carbon nanofiber/epoxy composites

PubMed Central

2011-01-01

The influence of the dispersion of vapor-grown carbon nanofibers (VGCNF) on the electrical properties of VGCNF/Epoxy composites has been studied. A homogenous dispersion of the VGCNF does not imply better electrical properties. In fact, it is demonstrated that the most simple of the tested dispersion methods results in higher conductivity, since the presence of well-distributed nanofiber clusters appears to be a key factor for increasing composite conductivity. PACS: 72.80.Tm; 73.63.Fg; 81.05.Qk PMID:21711873

Could binary mixture of Nd-Ni ions control the electrical behavior of strontium-barium M-type hexaferrite nanoparticles?

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

Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.com; Farooq, Saima

2011-05-15

Research highlights: {yields} Strontium-barium hexaferrites (Sr{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19}) in single magnetoplumbite phase solid structure are synthesized by the co-precipitation method. {yields} Structural and electrical properties of Nd-Ni substituted ferrites are investigated. {yields} These ferrite materials possess high electrical resistivity (108 {Omega} cm) that is essential to curb the eddy current loss, which is pre-requisite for surface mount devices. -- Abstract: Cationic substitution in M-type hexaferrites is considered to be an important tool for modification of their electrical properties. This work is part of our comprehensive study on the synthesis and characterization of Nd-Ni doped strontium-barium hexaferrite nanomaterials ofmore » nominal composition Sr{sub 0.5}Ba{sub 0.5-x}Nd{sub x}Fe{sub 12-y}Ni{sub y}O{sub 19} (x = 0.00-0.10; y = 0.00-1.00). Doping with this binary mixture modulates the physical and electrical properties of strontium-barium hexaferrite nanoparticles. Structural and electrical properties of the co-precipitated ferrites are investigated using state-of-the-art techniques. The results of X-ray diffraction analysis reveal that the lattice parameters and cell volume are inversely related to the dopant content. Temperature dependent DC-electrical resistivity measurements infer that resistivity of strontium-barium hexaferrites decreases from 1.8 x 10{sup 10} to 2.0 x 10{sup 8} {Omega} cm whereas the drift mobility, dielectric constant and dielectric loss tangent are directly related to the Nd-Ni content. The results of the study demonstrate a relationship between the modulation of electrical properties of substituted ferrites and nature of cations and their lattice site occupancy.« less

Choice of reconstructed tissue properties affects interpretation of lung EIT images.

PubMed

Grychtol, Bartłomiej; Adler, Andy

2014-06-01

Electrical impedance tomography (EIT) estimates an image of change in electrical properties within a body from stimulations and measurements at surface electrodes. There is significant interest in EIT as a tool to monitor and guide ventilation therapy in mechanically ventilated patients. In lung EIT, the EIT inverse problem is commonly linearized and only changes in electrical properties are reconstructed. Early algorithms reconstructed changes in resistivity, while most recent work using the finite element method reconstructs conductivity. Recently, we demonstrated that EIT images of ventilation can be misleading if the electrical contrasts within the thorax are not taken into account during the image reconstruction process. In this paper, we explore the effect of the choice of the reconstructed electrical properties (resistivity or conductivity) on the resulting EIT images. We show in simulation and experimental data that EIT images reconstructed with the same algorithm but with different parametrizations lead to large and clinically significant differences in the resulting images, which persist even after attempts to eliminate the impact of the parameter choice by recovering volume changes from the EIT images. Since there is no consensus among the most popular reconstruction algorithms and devices regarding the parametrization, this finding has implications for potential clinical use of EIT. We propose a program of research to develop reconstruction techniques that account for both the relationship between air volume and electrical properties of the lung and artefacts introduced by the linearization.

Aligned Single Wall Carbon Nanotube Polymer Composites Using an Electric Field

NASA Technical Reports Server (NTRS)

Park, Cheol; Wiklinson, John; Banda, Sumanth; Ounaies, Zoubeida; Wise, Kristopher E.; Sauti, Godfrey; Lillehei, Peter T.; Harrison, Joycelyn S.

2005-01-01

While high shear alignment has been shown to improve the mechanical properties of single wall carbon nanotubes (SWNT)-polymer composites, it is difficult to control and often results in degradation of the electrical and dielectric properties of the composite. Here, we report a novel method to actively align SWNTs in a polymer matrix, which allows for control over the degree of alignment of SWNTs without the side effects of shear alignment. In this process, SWNTs are aligned via field-induced dipolar interactions among the nanotubes under an AC electric field in a liquid matrix followed by immobilization by photopolymerization while maintaining the electric field. Alignment of SWNTs was controlled as a function of magnitude, frequency, and application time of the applied electric field. The degree of SWNT alignment was assessed using optical microscopy and polarized Raman spectroscopy and the morphology of the aligned nanocomposites was investigated by high resolution scanning electron microscopy. The structure of the field induced aligned SWNTs is intrinsically different from that of shear aligned SWNTs. In the present work, SWNTs are not only aligned along the field, but also migrate laterally to form thick, aligned SWNT percolative columns between the electrodes. The actively aligned SWNTs amplify the electrical and dielectric properties in addition to improving the mechanical properties of the composite. All of these properties of the aligned nanocomposites exhibited anisotropic characteristics, which were controllable by tuning the applied field conditions.

Optical response of semiconductors in a dc-electric field

NASA Astrophysics Data System (ADS)

Prussel, Lucie; Veniard, Valerie

A deep understanding of the optical properties of solids is crucial for the improvement of nonlinear materials and devices. It offers the opportunity to search for new materials with specific properties. One way to tune some of those properties is to apply an electrostatic field. This gives rise to electro-optic effects. The most known among those is the Pockel or linear electro-optic effect (LEO), which is a second order response property described by the susceptibility χ (2) (- ω ω , 0) . An important nonlinear process is the second harmonic generation (SHG), where two photons are absorbed by the material. While this process is sensitive to the symmetry of the material, adding a static field would enable a nonlinear response from every material, including centrosymmetric ones. This happens through a third order process, named EFISH (Electric Field Induced Second Harmonic) for which the susceptibility of interest is χ (3) (- 2 ω ω , ω , 0) . We have developed a theoretical approach and a numerical tool to study these two nonlinear properties (LEO and EFISH) in the context of Time-dependent Density Functional Theory (TDDFT), and we have applied it to the case of bulk SiC and GaAs as well as layered systems such as Ge/SiGe.

Properties of air-aluminum thermal plasmas

NASA Astrophysics Data System (ADS)

Cressault, Y.; Gleizes, A.; Riquel, G.

2012-07-01

We present the calculation and the main results of the properties of air-aluminum thermal plasmas, useful for complete modelling of arc systems involving aluminum contacts. The properties are calculated assuming thermal equilibrium and correspond to the equilibrium composition, thermodynamic functions, transport coefficients including diffusion coefficients and net emission coefficient representing the divergence of the radiative flux in the hottest plasma regions. The calculation is developed in the temperature range between 2000 and 30 000 K, for a pressure range from 0.1 to 1 bar and for several metal mass proportions. As in the case of other metals, the presence of aluminum vapours has a strong influence on three properties at intermediate temperatures: the electron number density, the electrical conductivity and the net emission coefficient. Some comparisons with other metal vapour (Cu, Fe and Ag) properties are made and show the original behaviour for Al-containing mixtures: mass density at high temperatures is low due to the low Al atomic mass; high electrical conductivity at T < 10 000 K due to low ionization potential (around 2 V less for Al than for the other metals); very strong self-absorption of ionized aluminum lines, leading to a net emission coefficient lower than that of pure air when T > 10 000 K, in contrast to copper or iron radiation.

Electrical transport across grain boundaries in graphene monolayers on SiC(0 0 0 \\bar{1} )

NASA Astrophysics Data System (ADS)

Zhou, Xiaodong; Ji, Shuai-Hua; Chockalingam, S. P.; Hannon, J. B.; Tromp, R. M.; Heinz, T. F.; Pasupathy, A. N.; Ross, F. M.

2018-07-01

We measure the role of structural defects, including grain boundaries and step edges, in determining the electrical transport characteristics of polycrystalline graphene monolayers synthesized on C-face SiC(0 0 0 ) by thermal decomposition. A combination of multi-probe scanning tunneling microscopy/potentiometry and low-energy electron microscopy allows the transport properties of individual grain boundaries to be correlated with their misorientation and atomic-level structure, without any device fabrication. We find that different types of grain boundary show dramatically different transport properties, and that boundaries can change structure and resistivity along their length. Boundary regions made up of dislocation superlattices separated by continuous graphene exhibit relatively low resistivity which is comparable to the resistivity of the graphene sheet itself. Other grain boundaries display trench structures with a resistivity 1–2 orders of magnitude greater and sufficient to dominate transport through the polycrystalline sheet. We also measure the transport properties of step edges and monolayer-bilayer boundaries on C-face graphene and compare them to Si-face graphene. Such measurements offer a guideline for optimizing graphene growth on SiC to improve its electronic properties.

Electrical and absorption properties of fresh cassava tubers and cassava starch

NASA Astrophysics Data System (ADS)

Harnsoongnoen, S.; Siritaratiwat, A.

2015-09-01

The objective of this study was to analyze the electrical and absorption properties of fresh cassava tubers and cassava starch at various frequencies using electric impedance spectroscopy and near-infrared spectroscopy, as well as determine the classification of the electrical parameters of both materials using the principle component analysis (PCA) method. All samples were measured at room temperature. The electrical and absorption parameters consisted of dielectric constant, dissipation factor, parallel capacitance, resistance, reactance, impedance and absorbance. It was found that the electrical and absorption properties of fresh cassava tubers and cassava starch were a function of frequency, and there were significant differences between the materials. The dielectric constant, parallel capacitance, resistance and impedance of fresh cassava tubers and cassava starch had similar dramatic decreases with increasing frequency. However, the reactance of both materials increased with an increasing frequency. The electrical parameters of both materials could be classified into two groups. Moreover, the dissipation factor and phase of impedance were the parameters that could be used in the separation of both materials. According to the absorbance patterns of the fresh cassava tubers and cassava starch, there were significant differences.

Modification of electrical properties of silicon dioxide through intrinsic nano-patterns

NASA Astrophysics Data System (ADS)

Majee, Subimal; Barshilia, Devesh; Banerjee, Debashree; Kumar, Sanjeev; Mishra, Prabhash; Akhtar, Jamil

2018-05-01

The inherent network of nanopores and voids in silicon dioxide (SiO2) is generally undesirable for aspects of film quality, electrical insulation and dielectric performance. However, if we view these pores as natural nano-patterns embedded in a dielectric matrix then that opens up new vistas for exploration. The nano-pattern platform can be used to tailor electrical, optical, magnetic and mechanical properties of the carrier film. In this article we report the tunable electrical properties of thermal SiO2 thin-film achieved through utilization of the metal-nanopore network where the pores are filled with metallic Titanium (Ti). Without any intentional chemical doping, we have shown that the electrical resistivity of the oxide film can be controlled through physical filling up of the intrinsic oxide nanopores with Ti. The electrical resistivity of the composite film remains constant even after complete removal of the metal from the film surface except the pores. Careful morphological, electrical and structural analyses are carried out to establish that the presence of Ti in the nanopores play a crucial role in the observed conductive nature of the nanoporous film.

Polymer composites with graphene nanofillers: electrical properties and applications.

PubMed

Tjong, Sie Chin

2014-02-01

Graphene with extraordinary high elastic modulus and excellent electrical conductivity has good prospects for use as the filler material for fabricating novel polymer composites designed for electrostatic discharge and EMI shielding protection, field emission, gas sensor, and fuel cell applications. Large amounts of graphene oxide (GO) can be obtained by wet chemical oxidation of graphite into a mixture of concentrated sulfuric acid, sodium nitrate and potassium permanganate. Accordingly, carbon atoms in the basal plane and edges of GO are decorated with oxygenated functional groups, forming an electrical insulator. To restore electrical conductivity, chemical reduction or thermal annealing is needed to eliminate oxygenated groups of GO. However, such treatments induce internal defects and remove oxygenated atoms of GO partially. The remnant-oxygenated groups affect electrical conductivity of graphene greatly. Nevertheless, reduced graphene oxide and thermally reduced graphene oxide are sufficiently conductive to form polymer nanocomposites at very low percolation threshold. This review provides the fundamentals and state-of-the-art developments in the fabrication methods and electrical property characterizations as well as the applications of novel graphene/polymer nanocomposites. Particular attention is paid to their processing-structural-electrical property relationships.

Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

DOEpatents

Ray, S.P.; Rapp, R.A.

1984-06-12

An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. 8 figs.

Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

DOEpatents

Ray, Siba P.; Rapp, Robert A.

1984-01-01

An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily.

Method of making composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

DOEpatents

Ray, Siba P.; Rapp, Robert A.

1986-01-01

An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily.

Ultra Thin Poly-Si Nanosheet Junctionless Field-Effect Transistor with Nickel Silicide Contact

PubMed Central

Lin, Yu-Ru; Tsai, Wan-Ting; Wu, Yung-Chun; Lin, Yu-Hsien

2017-01-01

This study demonstrated an ultra thin poly-Si junctionless nanosheet field-effect transistor (JL NS-FET) with nickel silicide contact. For the nickel silicide film, two-step annealing and a Ti capping layer were adopted to form an ultra thin uniform nickel silicide film with low sheet resistance (Rs). The JL NS-FET with nickel silicide contact exhibited favorable electrical properties, including a high driving current (>107A), subthreshold slope (186 mV/dec.), and low parasitic resistance. In addition, this study compared the electrical characteristics of JL NS-FETs with and without nickel silicide contact. PMID:29112139

Ultra Thin Poly-Si Nanosheet Junctionless Field-Effect Transistor with Nickel Silicide Contact.

PubMed

Lin, Yu-Ru; Tsai, Wan-Ting; Wu, Yung-Chun; Lin, Yu-Hsien

2017-11-07

This study demonstrated an ultra thin poly-Si junctionless nanosheet field-effect transistor (JL NS-FET) with nickel silicide contact. For the nickel silicide film, two-step annealing and a Ti capping layer were adopted to form an ultra thin uniform nickel silicide film with low sheet resistance (Rs). The JL NS-FET with nickel silicide contact exhibited favorable electrical properties, including a high driving current (>10⁷A), subthreshold slope (186 mV/dec.), and low parasitic resistance. In addition, this study compared the electrical characteristics of JL NS-FETs with and without nickel silicide contact.

Sediment-transport (wind) experiments in zero-gravity

NASA Technical Reports Server (NTRS)

Iverson, J.; Gillette, D.; Greeley, R.; Lee, J.; Mackinnon, I.; Marshall, J.; Nickling, W.; Werner, B.; White, B.; Williams, S.

1986-01-01

The carousel wind tunnel (CWT) can be a significant tool for the determination of the nature and magnitude of interparticlar forces at threshold of motion. By altering particle and drum surface electrical properties and/or by applying electric potential difference across the inner and outer drums, it should be possible to separate electrostatic effects from other forces of cohesion. Besides particle trajectory and bedform analyses, suggestions for research include particle aggregation in zero and subgravity environments, effect of suspension-saltation ratio on soil abrasion, and the effects of shear and shearfree turbulence on particle aggregation as applied to evolution of solar nebula.

Frequency-dependent local field factors in dielectric liquids by a polarizable force field and molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Davari, Nazanin; Haghdani, Shokouh; Åstrand, Per-Olof

2015-12-01

A force field model for calculating local field factors, i.e. the linear response of the local electric field for example at a nucleus in a molecule with respect to an applied electric field, is discussed. It is based on a combined charge-transfer and point-dipole interaction model for the polarizability, and thereby it includes two physically distinct terms for describing electronic polarization: changes in atomic charges arising from transfer of charge between the atoms and atomic induced dipole moments. A time dependence is included both for the atomic charges and the atomic dipole moments and if they are assumed to oscillate with the same frequency as the applied electric field, a model for frequency-dependent properties are obtained. Furthermore, if a life-time of excited states are included, a model for the complex frequency-dependent polariability is obtained including also information about excited states and the absorption spectrum. We thus present a model for the frequency-dependent local field factors through the first molecular excitation energy. It is combined with molecular dynamics simulations of liquids where a large set of configurations are sampled and for which local field factors are calculated. We are normally not interested in the average of the local field factor but rather in configurations where it is as high as possible. In electrical insulation, we would like to avoid high local field factors to reduce the risk for electrical breakdown, whereas for example in surface-enhanced Raman spectroscopy, high local field factors are desired to give dramatically increased intensities.

Surface electrical properties experiment, part 1. [for measuring lunar surface electrical properties

NASA Technical Reports Server (NTRS)

Kupfer, W. S. (Compiler)

1973-01-01

The design evolution, hardware development, and production history of the surface electrical properties (SEP) experiment are discussed. The SEP transmitter and receiver were designed to be used on the lunar surface during the Apollo 17 mission. The equipment was used to measure lunar surface electrical properties over traverses totalling more than 8 kilometers, for a duration of more than 100 minutes. A comprehensive outline of the techniques, is given along with a simplified detailed breakdown of equipment description and function to outline the principles of operation. A history of the design evolution with trade-off criteria and emphasis on changes caused by decisions reached in solving problems inherent in a fast-paced development program are presented from the viewpoint of overall design concept and in detail for each item of deliverable hardware. There is a brief account of lunar operations.

Electrical, optical, and photoluminescence properties of ZnO films subjected to thermal annealing and treatment in hydrogen plasma

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

Abdullin, Kh. A.; Gabdullin, M. T.; Gritsenko, L. V.

The photoluminescence and optical absorption spectra and electrical properties of ZnO films grown by the metal–organic chemical vapor deposition and hydrothermal techniques, subjected to heat treatments and plasma treatment in a hydrogen atmosphere, are studied. It is shown that the adsorption of oxygen at grain boundaries upon annealing in an oxidizing atmosphere determines the electrical properties of the films. Vacuum annealing improves the electrical properties of the samples after degradation induced by annealing in air. Treatment in hydrogen plasma passivates surface states at the grain boundaries. The intrinsic photoluminescence intensity after plasma treatment is higher in the case of increasedmore » amounts of oxygen adsorbed at grain surfaces upon annealing in air. Surface states involving oxygen and hydrogen atoms are responsible for the high-intensity intrinsic photoluminescence band.« less

Thermal and ac electrical properties of N-methylanthranilic acid below room temperature

NASA Astrophysics Data System (ADS)

Abdel-Kader, M. M.; Basha, M. A. F.; Ramzy, G. H.; Aboud, A. I.

2018-06-01

In this study, we investigated the thermal and alternating current (ac) electrical properties of N-methylanthranilic acid. Based on data obtained by differential scanning calorimetry, we detected two endothermic transitions at ≈ 213 K and ≈265.41 K. The weakening of hydrogen bonds as the temperature increased appeared to be the main cause of these phase transitions. We also recorded the melting point at about 475.5 K. Both the ac conductivity (σac) and complex dielectric constant (ε∗ = ε ' - jε ' ') were studied as functions of temperature over the frequency range from 1 kHz to 100 kHz. We observed significant variations in the thermal and electrical properties before and after the transition temperature at 265.41 K. The conduction mechanism responsible for the ac electrical properties before this transition was due to overlapping large polarons. These novel results are expected to have impacts on the application of organic semiconductors and dielectrics.

Analyte concentration at the tip of a nanopipette.

PubMed

Calander, Nils

2009-10-15

Concentration of molecules within the tips of nanopipettes when applying a DC voltage is herein investigated using finite-element simulations. The ion concentrations and fluxes due to diffusion, electro-migration, and electro-osmotic flow, and the electric potential are determined by the simultaneous solution of the Nernst-Planck, Poisson, and Navier-Stokes equations within the water solution containing sodium and chloride ions and negatively charged molecules. The electric potential within the pipette glass wall is at the same time determined by the Poisson equation together with appropriate boundary conditions and accounts for a field effect through the wall. Fixed negative surface charge on both the internal and external glass surfaces of the nanopipette is included together with the field effect through the glass wall to account for the electric double layer and the electro-osmosis. The inclusion of the field effect through the pipette wall is new compared to previous modeling of similar structures and is shown to be crucial for the behavior at the tip. It is demonstrated that the concentration of molecules is a consequence of ionic charge accumulation at the tip screening the electric field, thereby slowing down the electrophoretic motion of the molecules, which is further slowed down or stopped by the oppositely directed electro-osmosis. It is also shown that the trapping is very sensitive to the properties of the molecule, that is, its electrophoretic mobility and diffusion coefficient, the properties of the pipette, the ionic strength of the solution, and the applied electric field.

Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

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

2008-10-01

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

A study of the electrical properties of carbon nanofiber polymer composites

NASA Astrophysics Data System (ADS)

Cardoso, Paulo Jorge Magalhaes

The interest of industry on using carbon nanofibers (CNF) as a possible alternative to carbon nanotubes (CNT) to produce polymer based composites is due to their lower price, the ability to be produced in large amounts and the their usefulness as a reinforcement filler in order to improve the matrix properties such as mechanical, thermal and electrical. Polymers like epoxy resins already have good-to-excellent properties and an extensive range of applications, but the reinforcement with fillers like CNF, which has high aspect ratio (AR) and surface energy, has the potential to extend the range of applications. The Van der Waals interactions between nanofillers, such as CNF, promote the clustering effect which affects their dispersion in the polymer and may interfere with some properties of the nanocomposites. In this sense, it is very important to use appropriate dispersion methods which are able to disentangle the nanofillers to a certain degree, but avoiding the reduction of the nanofibers AR as much as possible. In fact, the methods and conditions of nanocomposites processing have also influence on the filler orientation, dispersion, distribution and aspect ratio. To the present day, there is a lack of complete information in the literature about the relation between structure and properties, in particular electrical properties, for polymer nanocomposites. The main objective of this work is to study the electrical properties of composites based on CNF and epoxy resin using production methods which can be easily implemented in industrial environments and that provide different dispersion levels, investigating therefore the relationship between dispersion level and electrical response. Some of the requirements for such methods are the adaptability to the industrial processes and facilities which allow large scale productions and provide a good relation between quality and cost of the composite materials. In this work, morphological, electrical and electromechanical studies were performed in epoxy resin composites with vapor-grown carbon nanofibers (VGCNF). First, the electrical properties of VGCNF/epoxy resin composites produced with a simple method were studied. Then, it was investigated the relation between the electrical properties and the dispersion level of VGCNF/epoxy composites produced with different methods, which were selected to provide different levels of dispersion.The level of nanofiber dispersion of the composites produced with the different methods and filler contents was analyzed by transmission optical microscopy (TOM) and greyscale analysis (GSA) and then compared to the electrical conductivity measurements. After this study, the influence of different methods of VGCNF dispersion on the electrical conduction mechanism of the composites was investigated. Then, these composites were submitted to electromechanical tests in order to apply them as piezoresistive sensors. The last study of this work was dedicated to an initial comparison between the epoxy composites with VGCNG and multi-walled carbon nanotubes (MWCNT), in terms of electrical and morphological properties. As the main outcomes of the present work, it can be concluded that a better cluster dispersion seems to be more suitable than good filler dispersion for achieving larger electrical conductivities and lower percolation thresholds. It is also concluded that hopping conductivity is a relevant mechanism for determining the overall conductivity of the composites and that the CNF/epoxy composites are appropriate materials for piezoresistive sensors in particular at concentrations close to the percolation threshold.

Split-mode ultrasonic transducer.

PubMed

Ostrovskii, Igor; Cremaldi, Lucien

2013-08-01

A split-mode ultrasonic transducer is investigated in both theory and experiment. This transducer is a two-dimensional structure of periodically poled domains in a ferroelectric wafer with free surfaces. The acoustic vibrations are excited by a radio frequency electric current applied along the length of the wafer, which allows the basal-plane surfaces to be free of metal coatings and thus ready for further biomedical applications. A specific physical property of this transducer consists of the multiple acousto-electric resonances, which occur due to an acoustic mode split when the acoustic half-wavelength is equal to the domain length. Possible applications include ultrasonic generation and detection at the micro-scale, intravascular sonification and visualization, ultrasound therapy of localized small areas such as the eye, biomedical applications for cell cultures, and traditional nondestructive testing including bones and tissues. A potential use of a non-metallized wafer is a therapeutic application with double action that is both ultrasound itself and an electric field over the wafer. The experimental measurements and theoretical calculations are in good agreement.

The Elusive Memristor: Properties of Basic Electrical Circuits

ERIC Educational Resources Information Center

Joglekar, Yogesh N.; Wolf, Stephen J.

2009-01-01

We present an introduction to and a tutorial on the properties of the recently discovered ideal circuit element, a memristor. By definition, a memristor M relates the charge "q" and the magnetic flux [phi] in a circuit and complements a resistor R, a capacitor C and an inductor L as an ingredient of ideal electrical circuits. The properties of…

Physical properties of Ce-TZP at cryogenic temperature

NASA Astrophysics Data System (ADS)

Han, Y. M.; Chen, Z.; Zhou, M.; Huang, R. J.; Huang, C. J.; Li, L. F.

2014-01-01

Electrical insulators, which are used to insulate cryogenic supply lines and conductor windings, are critical units in superconducting TOKAMAK magnets. Electrical insulators used in superconducting magnets fall into axial and radial insulators. These insulators can be made from glass ribbon epoxy densification and have been used in the Experiment Advanced Superconducting Tokamak (EAST). The properties of Ce-TZP can satisfy the requirement of electrical insulators. In this paper, thermal conductivity, mechanical properties and coefficient of thermal expansion of Ce-TZP have been investigated at cryogenic temperatures. Results indicate that the Ce-TZP shows better properties than epoxy and it demonstrates that the Ce-TZP can be used as insulation material in superconducting magnets.

Effect of rapid thermal annealing on the electrical, optical and structural properties of ZnO-doped In2O3 films grown by linear facing target sputtering.

PubMed

Cho, Chung-Ki; Kim, Han-Ki

2012-04-01

We investigated the effect of rapid thermal annealing on the electrical, optical, and structural properties of ZnO-doped In2O3 (ZIO) films grown at different Ar/O2 flow ratios (15/0 and 15/1 sccm) by using linear facing target sputtering. It was found that the ZIO films grown at different Ar/O2, flow ratios showed different electrical and optical behavior with increasing rapid thermal annealing temperature. Synchrotron X-ray scattering examination showed that the different electrical and optical properties of the ZIO films could be attributed to the difference in preferred orientation with an increase in rapid thermal annealing temperature.

Magnetic and electrical properties of Nd7Pt3 studied on single crystals

NASA Astrophysics Data System (ADS)

Tsutaoka, Takanori; Ueda, Koyo; Matsushita, Takuya

2018-07-01

Magnetic and electrical properties of Nd7Pt3 with the Th7Fe3 type hexagonal structure have been studied on single crystals by measuring magnetization, magnetic susceptibility and electrical resistivity. Nd7Pt3 possesses a ferromagnetic state below TC = 38 K; a canted antiferromagnetic state takes place at Tt2 = 34 K. Another magnetic phase transition has also been observed at Tt1 = 25 K. The magnetization curve along the a- and b-axes at 2 K shows anomalous first-order irreversible behavior. The direction of the magnetic moment in the canted state can be tilted from the c-plane. Electrical resistivity measurement results show metallic property; three anomalies were observed at Tt1, Tt2 and TC, respectively.

Electrical Transport Properties of Liquid Al-Cu Alloys

NASA Astrophysics Data System (ADS)

Thakore, B. Y.; Khambholja, S. G.; Suthar, P. H.; Jani, A. R.

2010-06-01

Electrical transport properties viz. electrical resistivity, thermoelectric power and thermal conductivity of liquid Al-Cu alloys as a function of Cu concentration have been studied in the present paper. Ashcroft empty core model potential has been used to incorporate the ion-electron interaction. To incorporate the exchange and correlation effects, five different forms of local field correction functions viz. Hartree, Taylor, Ichimaru et al., Farid et al. and Sarkar et al. have been used. The transport properties of binary system have been studied using Faber-Ziman formulation combined with Ashcroft-Langreth (AL) partial structure factor. The computed values of electrical resistivity are compared with experimental data and for low Cu concentration, good agreement has been observed. Further, thermoelectric power and thermal conductivity have also been predicted.

Evaluation on expansive performance of the expansive soil using electrical responses

NASA Astrophysics Data System (ADS)

Chu, Ya; Liu, Songyu; Bate, Bate; Xu, Lei

2018-01-01

Light structures, such as highways and railroads, built on expansive soils are prone to damages from the swelling of their underlain soil layers. Considerable amount of research has been conducted to characterize the swelling properties of expansive soils. Current swell characterization models, however, are limited by lack of standardized tests. Electrical methods are non-destructive, and are faster and less expensive than the traditional geotechnical methods. Therefore, geo-electrical methods are attractive for defining soil characteristics, including the swelling behavior. In this study, comprehensive laboratory experiments were undertaken to measure the free swelling and electrical resistivity of the mixtures of commercial kaolinite and bentonite. The electrical conductivity of kaolinite-bentonite mixtures was measured by a self-developed four-electrode soil resistivity box. Increasing the free swelling rate of the kaolinite-bentonite mixtures (0.72 to 1 of porosity of soils samples) led to a reduction in the electrical resistivity and an increase in conductivity. A unique relationship between free swelling rate and normalized surface conductivity was constructed for expensive soils by eliminating influences of porosity and m exponent. Therefore, electrical response measurement can be used to characterize the free swelling rate of expensive soils.

Electromagnetic coupling of spins and pseudospins in bilayer graphene

NASA Astrophysics Data System (ADS)

Winkler, R.; Zülicke, U.

2015-03-01

We present a theoretical study of bilayer-graphene's electronic properties in the presence of electric and magnetic fields. In contrast to known materials, including single-layer graphene, any possible coupling of physical quantities to components of the electric field has a counterpart where the analogous component of the magnetic field couples to exactly the same quantities. For example, a purely electric spin splitting appears as the magneto-electric analogue of the magnetic Zeeman spin splitting. The measurable thermodynamic response induced by magnetic and electric fields is thus completely symmetric. The Pauli magnetization induced by a magnetic field takes exactly the same functional form as the polarization induced by an electric field. Although they seem counterintuitive, our findings are consistent with fundamental principles such as time reversal symmetry. For example, only a magnetic field can give rise to a macroscopic spin polarization, whereas only a perpendicular electric field can induce a macroscopic polarization of the sublattice-related pseudospin in bilayer graphene. These rules enforced by symmetry for the matter-field interactions clarify the nature of spins versus pseudospins. We have obtained numerical values of prefactors for relevant terms. NSF Grant DMR-1310199 and Marsden Fund Contract No. VUW0719.

Collagen Hydrolysates of Skin Shavings Prepared by Enzymatic Hydrolysis as a Natural Flocculant and Their Flocculating Property.

PubMed

Fu, Ruijie; Yao, Kai; Zhang, Qisheng; Jia, Dongying; Zhao, Jiayuan; Chi, Yuanlong

2017-05-01

A series of collagen hydrolysates (CHs) were prepared from pigskin shavings by using pepsin (PCH), trypsin (TCH), Alcalase (ACH), HCl (HCH), and NaOH (NCH). Their physicochemical properties, including degree of collagen hydrolysis, molecular weight distribution, electric charge, and microstructure, were investigated, and their flocculation performance was evaluated in a kaolin suspension, at varied pHs and concentrations. PCH exhibited high flocculation capability under acidic and neutral conditions, and its efficiency for removing suspended particles was approximately 80% at a concentration of 0.05 g/L. TCH, ACH, HCH, and NCH showed almost no flocculation capability. The flocculation capability of PCH could be mainly due to a combination of optimal molecular weight distribution and electric charge. This study could provide an environment-friendly natural flocculant and also proposes a promising approach for the reuse of collagen wastes. Graphical Abstract ᅟ.

Effect of surface roughness of trench sidewalls on electrical properties in 4H-SiC trench MOSFETs

NASA Astrophysics Data System (ADS)

Kutsuki, Katsuhiro; Murakami, Yuki; Watanabe, Yukihiko; Onishi, Toru; Yamamoto, Kensaku; Fujiwara, Hirokazu; Ito, Takahiro

2018-04-01

The effects of the surface roughness of trench sidewalls on electrical properties have been investigated in 4H-SiC trench MOSFETs. The surface roughness of trench sidewalls was well controlled and evaluated by atomic force microscopy. The effective channel mobility at each measurement temperature was analyzed on the basis of the mobility model including optical phonon scattering. The results revealed that surface roughness scattering had a small contribution to channel mobility, and at the arithmetic average roughness in the range of 0.4-1.4 nm, there was no correlation between the experimental surface roughness and the surface roughness scattering mobility. On the other hand, the characteristics of the gate leakage current and constant current stress time-dependent dielectric breakdown tests demonstrated that surface morphology had great impact on the long-term reliability of gate oxides.

Optical properties of the Tietz-Hua quantum well under the applied external fields

NASA Astrophysics Data System (ADS)

Kasapoglu, E.; Sakiroglu, S.; Ungan, F.; Yesilgul, U.; Duque, C. A.; Sökmen, I.

2017-12-01

In this study, the effects of the electric and magnetic fields as well as structure parameter- γ on the total absorption coefficient, including linear and third order nonlinear absorption coefficients for the optical transitions between any two subband in the Tietz-Hua quantum well have been investigated. The optical transitions were investigated by using the density matrix formalism and the perturbation expansion method. The Tietz-Hua quantum well becomes narrower (wider) when the γ - structure parameter increases (decreases) and so the energies of the bound states will be functions of this parameter. Therefore, we can provide the red or blue shift in the peak position of the absorption coefficient by changing the strength of the electric and magnetic fields as well as the structure parameters and these results can be used to adjust and control the optical properties of the Tietz-Hua quantum well.

Adjusting alloy compositions for selected properties in temperature limited heaters

DOEpatents

Brady; Michael Patrick , Horton, Jr.; Joseph Arno , Vitek; John Michael

2010-03-23

Heaters for treating a subsurface formation are described herein. Such heaters can be obtained by using the systems and methods described herein. The heater includes a heater section including iron, cobalt, and carbon. The heater section has a Curie temperature less than a phase transformation temperature. The Curie temperature is at least 740.degree. C. The heater section provides, when time varying current is applied to the heater section, an electrical resistance.

Breakdown characteristics of SF6/N2 in severely non-uniform electric fields at low temperatures

NASA Astrophysics Data System (ADS)

Wang, Y.; Gao, Z. W.; Li, G. X.; Zhu, X. C.; Yu, C. L.; Liang, J. Q.; Li, L.

2018-01-01

SF6 has good electrical insulating properties, which is widely used as an insulating medium of GIS, GIL and other electrical equipment. However, the reliability of electrical equipments´ insulated gas is greatly challenged in cold areas, since SF6 more readily liquefies. To solve the problem, SF6 can be mixed with N2 to maintain the insulating properties, and reduce its liquefaction temperature. Such practice has certain application prospect. In this paper, a breakdown experimental platform was built to study the insulating property of SF6/N2 at low temperature, wherein the temperature of the platform can be adjusted. A severely non-uniform electric field was generated by a rod-plate electrode. The breakdown characteristics of SF6/N2 with different mixing proportions at low pressures and low temperatures were measured. The result showed that the mixed gas was not liquefied within the temperature range. Temperature had insignificant influence on the insulating property thereof. The result in the paper has certain guiding significance for applying SF6/N2 mixed gas in high latitude areas.

Engineering of electronic properties of single layer graphene by swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Kumar, Ashish; Tripathi, Ambuj; Tyagi, Chetna; Avasthi, D. K.

2018-04-01

In this work, swift heavy ion irradiation induced effects on the electrical properties of single layer graphene are reported. The modulation in minimum conductivity point in graphene with in-situ electrical measurement during ion irradiation was studied. It is found that the resistance of graphene layer decreases at lower fluences up to 3 × 1011 ions/cm2, which is accompanied by the five-fold increase in electron and hole mobilities. The ion irradiation induced increase in electron and hole mobilities at lower fluence up to 1 × 1011 ions/cm2 is verified by separate Hall measurements on another irradiated graphene sample at the selected fluence. In contrast to the adverse effects of irradiation on the electrical properties of materials, we have found improvement in electrical mobility after irradiation. The increment in mobility is explained by considering the defect annealing in graphene after irradiation at a lower fluence regime. The modification in carrier density after irradiation is also observed. Based on findings of the present work, we suggest ion beam irradiation as a useful tool for tuning of the electrical properties of graphene.

Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet

NASA Astrophysics Data System (ADS)

Iguchi, Yusuke; Nii, Yoichi; Onose, Yoshinori

Control of physical property in terms of external fields is essential for contemporary technologies. The conductance can be controlled by a gate electric field in a field effect transistor, which is a main component of the integrated circuit. Optical phenomena induced by an electric field such as electroluminescence and electrochromism are useful for display and other technologies. Control of microwave propagation seems also imperative for future wireless communication technology. Microwave properties in solids are dominated mostly by magnetic excitations, which cannot be easily controlled by an electric field. One of the solutions for this problem is utilizing magnetically induced ferroelectrics (multiferroics). Here we show that microwave nonreciprocity, which is difference between oppositely propagating microwaves, can be reversed by the external electric field in a multiferroic helimagnet Ba2Mg2Fe12O22. This result offers a new avenue for the electrical control of microwave properties.

Magnetoelectrical control of nonreciprocal microwave response in a multiferroic helimagnet

NASA Astrophysics Data System (ADS)

Iguchi, Y.; Nii, Y.; Onose, Y.

2017-05-01

The control of physical properties by external fields is essential in many contemporary technologies. For example, conductance can be controlled by a gate electric field in a field effect transistor, which is a main component of integrated circuits. Optical phenomena induced by an electric field such as electroluminescence and electrochromism are useful for display and other technologies. Control of microwave propagation is also important for future wireless communication technology. Microwave properties in solids are dominated mostly by magnetic excitations, which cannot be easily controlled by an electric field. One solution to this problem is to use magnetically induced ferroelectrics (multiferroics). Here we show that microwave nonreciprocity, that is, different refractive indices for microwaves propagating in opposite directions, could be reversed by an external electric field in a multiferroic helimagnet Ba2Mg2Fe12O22. This approach offers an avenue for the electrical control of microwave properties.

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.

Researching the electrical properties of single A3B5 nanowires

NASA Astrophysics Data System (ADS)

Vasiliev, A. A.; Mozharov, A. M.; Komissarenko, F. E.; Cirlin, G. E.; Bouravlev, D. A.; Mukhin, I. S.

2017-11-01

We investigate electrical characteristics of GaN, GaAs and GaP NWs which are grown with MOCVD and MBE. We developed measurement technique and it allows to determine the required properties of the structures.

Low electrical resistivity carbon nanotube and polyethylene nanocomposites for aerospace and energy exploration applications

NASA Astrophysics Data System (ADS)

Moloney, Padraig G.

An investigation was conducted towards the development and optimization of low electrical resistivity carbon nanotube (CNT) and thermoplastic composites as potential materials for future wire and cable applications in aerospace and energy exploration. Fundamental properties of the polymer, medium density polyethylene (MDPE), such as crystallinity were studied and improved for composite use. A parallel effort was undertaken on a broad selection of CNT, including single wall, double wall and multi wall carbon nanotubes, and included research of material aspects relevant to composite application and low resistivity such as purity, diameter and chirality. With an emphasis on scalability, manufacturing and purification methods were developed, and a solvent-based composite fabrication method was optimized. CNT MDPE composites were characterized via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman spectroscopy, and multiple routes of electron microscopy. Techniques including annealing and pressure treatments were used to further improve the composites' resulting electrical performance. Enhancement of conductivity was explored via exposure to a focused microwave beam. A novel doping method was developed using antimony pentafluoride (SbF5) to reduce the resistivity of the bulk CNT. Flexible composites, malleable under heat and pressure, were produced with exceptional electrical resistivities reaching as low as 2*10-6O·m (5*105S/m). A unique gas sensor application utilizing the unique electrical resistivities of the produced CNT-MDPE composites was developed. The materials proved suitable as a low weight and low energy sensing material for dimethyl methylphosphonate (DMMP), a nerve gas simulant.

Degradation mechanisms of optoelectric properties of GaN via highly-charged 209Bi33+ ions irradiation

NASA Astrophysics Data System (ADS)

Zhang, L. Q.; Zhang, C. H.; Xian, Y. Q.; Liu, J.; Ding, Z. N.; Yan, T. X.; Chen, Y. G.; Su, C. H.; Li, J. Y.; Liu, H. P.

2018-05-01

N-type gallium nitride (GaN) epitaxial layers were subjected to 990-keV Bi33+ ions irradiation to various fluences. Optoelectric properties of the irradiated-GaN specimens were studied by means of Raman scattering and variable temperature photoluminescence (PL) spectroscopy. Raman spectra reveal that both the free-carrier concentration and its mobility generally decrease with a successive increase in ion fluence. Electro-optic mechanisms dominated the electrical transport to a fluence of 1.061 × 1012 Bi33+/cm2. Above this fluence, electrical properties were governed by the deformation potential. The appearance of vacancy-type defects results in an abrupt degradation in electrical transports. Varying temperature photoluminescence (PL) spectra display that all emission lines of 1.061 × 1012 Bi33+/cm2-irradiated specimen present a general remarkable thermal redshift, quenching, and broadening, including donor-bound-exciton peak, yellow luminescence band, and LO-phonon replicas. Moreover, as the temperature rises, a transformation from excitons (donor-acceptor pairs' luminescence) to band-to-band transitions (donor-acceptor combinations) was found, and the shrinkage effect of the band gap dominated the shift of the peak position gradually, especially the temperature increases above 150 K. In contrast to the un-irradiated specimen, a sensitive temperature dependence of all photoluminescence (PL) lines' intensity obtained from 1.061 × 1012 Bi33+/cm2-irradiated specimen was found. Mechanisms underlying were discussed.

Electrokinetic transport properties of deoxynucleotide monophosphates (dNMPs) through thermoplastic nanochannels.

PubMed

O'Neil, Colleen; Amarasekara, Charuni A; Weerakoon-Ratnayake, Kumuditha M; Gross, Bethany; Jia, Zheng; Singh, Varshni; Park, Sunggook; Soper, Steven A

2018-10-16

The electrokinetic behavior of molecules in nanochannels (<100 nm in length) have generated interest due to the unique transport properties observed that are not seen in microscale channels. These nanoscale dependent transport properties include transverse electromigration arising from partial electrical double layer overlap, enhanced solute/wall interactions due to the small channel diameter, and field-dependent intermittent motion produced by surface roughness. In this study, the electrokinetic transport properties of deoxynucleotide monophosphates (dNMPs) were investigated, including the effects of electric field strength, surface effects, and composition of the carrier electrolyte (ionic concentration and pH). The dNMPs were labeled with a fluorescent reporter (ATTO 532) to allow tracking of the electrokinetic transport of the dNMPs through a thermoplastic nanochannel fabricated via nanoimprinting (110 nm × 110 nm, width × depth, and 100 μm in length). We discovered that the transport properties in plastic nanochannels of the dye-labeled dNMPs produced differences in their apparent mobilities that were not seen using microscale columns. We built histograms for each dNMP from their apparent mobilities under different operating conditions and fit the histograms to Gaussian functions from which the separation resolution could be deduced as a metric to gage the ability to identify the molecule based on their apparent mobility. We found that the resolution ranged from 0.73 to 2.13 at pH = 8.3. Changing the carrier electrolyte pH > 10 significantly improved separation resolution (0.80-4.84) and reduced the standard deviation in the Gaussian fit to the apparent mobilities. At low buffer concentrations, decreases in separation resolution and increased standard deviations in Gaussian fits to the apparent mobilities of dNMPs were observed due to the increased thickness of the electric double layer leading to a partial parabolic flow profile. The results secured for the dNMPs in thermoplastic nanochannels revealed a high identification efficiency (>99%) in most cases for the dNMPs due to differences in their apparent mobilities when using nanochannels, which could not be achieved using microscale columns. Copyright © 2018. Published by Elsevier B.V.

Spatial and temporal dependence of the convective electric field in Saturn’s inner magnetosphere

NASA Astrophysics Data System (ADS)

Andriopoulou, M.; Roussos, E.; Krupp, N.; Paranicas, C.; Thomsen, M.; Krimigis, S.; Dougherty, M. K.; Glassmeier, K.-H.

2014-02-01

The recently established presence of a convective electric field in Saturn’s inner and middle magnetosphere, with an average pointing approximately towards midnight and an intensity less than 1 mV/m, is one of the most puzzling findings by the Cassini spacecraft. In order to better characterize the properties of this electric field, we augmented the original analysis method used to identify it (Andriopoulou et al., 2012) and applied it to an extended energetic electron microsignature dataset, constructed from observations at the vicinity of four saturnian moons. We study the average characteristics of the convective pattern and additionally its temporal and spatial variations. In our updated dataset we include data from the recent Cassini orbits and also microsignatures from the two moons, Rhea and Enceladus, allowing us to further extend this analysis to cover a greater time period as well as larger radial distances within the saturnian magnetosphere. When data from the larger radial range and more recent orbits are included, we find that the originally inferred electric field pattern persists, and in fact penetrates at least as far in as the orbit of Enceladus, a region of particular interest due to the plasma loading that takes place there. We perform our electric field calculations by setting the orientation of the electric field as a free, time-dependent parameter, removing the pointing constraints from previous works. Analytical but also numerical techniques have been employed, that help us overcome possible errors that could have been introduced from simplified assumptions used previously. We find that the average electric field pointing is not directed exactly at midnight, as we initially assumed, but is found to be stably displaced by approximately 12-32° from midnight, towards dawn. The fact, however, that the field’s pointing is much more variable in short time scales, in addition to our observations that it penetrates inside the orbit of Enceladus (∼4 Rs), may suggest that the convective pattern is dominating all the way down to the main rings (2.2 Rs), when data from the Saturn Orbit Insertion are factored in. We also report changes of the electric field strength and pointing over the course of time, possibly related to seasonal effects, with the largest changes occurring during a period that envelopes the saturnian equinox. Finally, the average electric field strength seems to be sensitive to radial distance, exhibiting a drop as we move further out in the magnetosphere, confirming earlier results. This drop-off, however, appears to be more intense in the earlier years of the mission. Between 2010 and 2012 the electric field is quasi-uniform, at least between the L-shells of Tethys and Dione. These new findings provide constraints in the possible electric field sources that might be causing such a convection pattern that has not been observed before in other planetary magnetospheres. The very well defined values of the field’s average properties may suggest a periodic variation of the convective pattern, which can average out very effectively the much larger changes in both pointing and intensity over short time scales, although this period cannot be defined. The slight evidence of changes in the properties across the equinox (seasonal control), may also hint that the source of the electric field resides in the planet’s atmosphere/ionosphere system.

Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

NASA Astrophysics Data System (ADS)

Bertolotto, Jorge A.; Umazano, Juan P.

2016-06-01

In the present work we make a theoretical study of the steady state electric linear dichroism of DNA fragments in aqueous solution. The here developed theoretical approach considers a flexible bent rod model with a saturating induced dipole moment. The electric polarizability tensor of bent DNA fragments is calculated considering a phenomenological model which theoretical and experimental backgroung is presented here. The model has into account the electric polarizability longitudinal and transversal to the macroion. Molecular flexibility is described using an elastic potential. We consider DNA fragments originally bent with bending fluctuations around an average bending angle. The induced dipole moment is supposed constant once the electric field strength grows up at critical value. To calculate the reduced electric linear dichroism we determine the optical factor considering the basis of the bent DNA perpendicular to the molecular axis. The orientational distribution function has into account the anisotropic electric properties and the molecule flexibility. We applied the present theoretical background to fit electric dichroism experimental data of DNA fragments reported in the bibliography in a wide range of molecular weight and electric field. From these fits, values of DNA physical properties are estimated. We compare and discuss the results here obtained with the theoretical and experimental data presented by other authors. The original contributions of this work are: the inclusion of the transversal electric polarizability saturating with the electric field, the description of the electric properties with an electric polarizability tensor dependant on the bending angle and the use of an arc model originally bent.

ROLE OF THE NETWORK FORMER IN SEMICONDUCTING OXIDE GLASSES.

DTIC Science & Technology

SEMICONDUCTOR DEVICES, * GLASS ), (*ELECTRICAL NETWORKS, GLASS ), ELECTRICAL PROPERTIES, SEEBECK EFFECT, BORATES, PHOSPHATES, ELECTRICAL RESISTANCE, X RAY DIFFRACTION, ANNEALING, OXIDATION, OXIDES, ELECTRODES, VANADIUM

Nonequilibrium response of an electron-mediated charge density wave ordered material to a large dc electric field

NASA Astrophysics Data System (ADS)

Matveev, O. P.; Shvaika, A. M.; Devereaux, T. P.; Freericks, J. K.

2016-01-01

Using the Kadanoff-Baym-Keldysh formalism, we employ nonequilibrium dynamical mean-field theory to exactly solve for the nonlinear response of an electron-mediated charge-density-wave-ordered material. We examine both the dc current and the order parameter of the conduction electrons as the ordered system is driven by the electric field. Although the formalism we develop applies to all models, for concreteness, we examine the charge-density-wave phase of the Falicov-Kimball model, which displays a number of anomalous behaviors including the appearance of subgap density of states as the temperature increases. These subgap states should have a significant impact on transport properties, particularly the nonlinear response of the system to a large dc electric field.

The efficiency of ultrasonic oscillations transfer into the load

NASA Astrophysics Data System (ADS)

Abramov, O. V.; Abramov, V. O.; Mullakaev, M. S.; Artem'ev, V. V.

2009-11-01

The results of ultrasonic action to the substances have been presented. It is examined, the correlation between the electrical parameters of ultrasonic equipment and acoustic performances of the ultrasonic field in treating the medium, the efficiency of ultrasonic technological facility, and the peculiarities of oscillations introduced into the load under cavitation development. The correlation between the acoustic powers of oscillations securing the needed level of cavitation and desired technological effect, and the electrical parameters of the ultrasonic facility, first of all, the power, is established. The peculiarities of cavitation development in liquids with different physical-chemical properties (including the molten low-melting metals) have been studied, and the acoustic power of oscillations introduced into the load under input variation of electric power to the generator has been also estimated.

The Electric Propulsion Interactions Code (EPIC)

NASA Technical Reports Server (NTRS)

Mikellides, I. G.; Mandell, M. J.; Kuharski, R. A.; Davis, V. A.; Gardner, B. M.; Minor, J.

2004-01-01

Science Applications International Corporation is currently developing the Electric Propulsion Interactions Code, EPIC, as part of a project sponsored by the Space Environments and Effects Program at the NASA Marshall Space Flight Center. Now in its second year of development, EPIC is an interactive computer tool that allows the construction of a 3-D spacecraft model, and the assessment of a variety of interactions between its subsystems and the plume from an electric thruster. These interactions may include erosion of surfaces due to sputtering and re-deposition of sputtered materials, surface heating, torque on the spacecraft, and changes in surface properties due to erosion and deposition. This paper describes the overall capability of EPIC and provides an outline of the physics and algorithms that comprise many of its computational modules.

Mechanisms of transport and electron transfer at conductive polymer/liquid interfaces

NASA Astrophysics Data System (ADS)

Ratcliff, Erin

Organic semiconductors (OSCs) have incredible prospects for next-generation, flexible electronic devices including bioelectronics, thermoelectrics, opto-electronics, and energy storage and conversion devices. Yet many fundamental challenges still exist. First, solution processing prohibits definitive control over microstructure, which is fundamental for controlling electrical, ionic, and thermal transport properties. Second, OSCs generally suffer from poor electrical conductivities due to a combination of low carriers and low mobility. Third, polymeric semiconductors have potential-dependent, dynamically evolving electronic and chemical states, leading to complex interfacial charge transfer properties in contact with liquids. This talk will focus on the use of alternative synthetic strategies of oxidative chemical vapor deposition and electrochemical deposition to control physical, electronic, and chemical structure. We couple our synthetic efforts with energy-, time-, and spatially resolved spectroelectrochemical and microscopy techniques to understand the critical interfacial chemistry-microstructure-property relationships: first at the macroscale, and then moving towards the nanoscale. In particular, approaches to better understand electron transfer events at polymer/liquid interfaces as a function of: 1.) chemical composition; 2.) electronic density of states (DOS); and 3.) crystallinity and microstructure will be discussed.

Nanoporous delafossite CuAlO2 from inorganic/polymer double gels: a desirable high-surface-area p-type transparent electrode material.

PubMed

Das, Barun; Renaud, Adèle; Volosin, Alex M; Yu, Lei; Newman, Nathan; Seo, Dong-Kyun

2015-02-02

Nanoporous structures of a p-type semiconductor, delafossite CuAlO(2), with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott-Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO(2) are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott-Schottky plot from the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO(2) exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.

Nanoporous Delafossite CuAlO 2 from Inorganic/Polymer Double Gels: A Desirable High-Surface-Area p-Type Transparent Electrode Material

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

Das, Barun; Renaud, Adèle; Volosin, Alex M.

2015-02-02

Nanoporous structures of a p-type semiconductor, delafossite CuAlO2, with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott–Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO2 are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott–Schottky plot from the electrochemicalmore » impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO2 exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.« less

Nanoporous Delafossite CuAlO 2 from Inorganic/Polymer Double Gels: A Desirable High-Surface-Area p-Type Transparent Electrode Material

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

Das, Barun; Renaud, Adèle; Volosin, Alex M.

2015-02-02

Nanoporous structures of a p-type semiconductor, delafossite CuAlO 2, with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott–Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO 2 are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott–Schottky plot frommore » the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO 2 exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.« less

Boron nitride nanotubes and nanosheets.

PubMed

Golberg, Dmitri; Bando, Yoshio; Huang, Yang; Terao, Takeshi; Mitome, Masanori; Tang, Chengchun; Zhi, Chunyi

2010-06-22

Hexagonal boron nitride (h-BN) is a layered material with a graphite-like structure in which planar networks of BN hexagons are regularly stacked. As the structural analogue of a carbon nanotube (CNT), a BN nanotube (BNNT) was first predicted in 1994; since then, it has become one of the most intriguing non-carbon nanotubes. Compared with metallic or semiconducting CNTs, a BNNT is an electrical insulator with a band gap of ca. 5 eV, basically independent of tube geometry. In addition, BNNTs possess a high chemical stability, excellent mechanical properties, and high thermal conductivity. The same advantages are likely applicable to a graphene analogue-a monatomic layer of a hexagonal BN. Such unique properties make BN nanotubes and nanosheets a promising nanomaterial in a variety of potential fields such as optoelectronic nanodevices, functional composites, hydrogen accumulators, electrically insulating substrates perfectly matching the CNT, and graphene lattices. This review gives an introduction to the rich BN nanotube/nanosheet field, including the latest achievements in the synthesis, structural analyses, and property evaluations, and presents the purpose and significance of this direction in the light of the general nanotube/nanosheet developments.

EFFECTS OF TRITIUM GAS EXPOSURE ON THE GLASS TRANSITION TEMPERATURE OF EPDM ELASTOMER AND ON THE CONDUCTIVITY OF POLYANILINE

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

Clark, E; Marie Kane, M

2008-12-12

Four formulations of EPDM (ethylene-propylene diene monomer) elastomer were exposed to tritium gas initially at one atmosphere and ambient temperature for between three and four months in closed containers. Material properties that were characterized include density, volume, mass, appearance, flexibility, and dynamic mechanical properties. The glass transition temperature was determined by analysis of the dynamic mechanical property data per ASTM standards. EPDM samples released significant amounts of gas when exposed to tritium, and the glass transition temperature increased by about 3 C. during the exposure. Effects of ultraviolet and gamma irradiation on the surface electrical conductivity of two types ofmore » polyaniline films are also documented as complementary results to planned tritium exposures. Future work will determine the effects of tritium gas exposure on the electrical conductivity of polyaniline films, to demonstrate whether such films can be used as a sensor to detect tritium. Surface conductivity was significantly reduced by irradiation with both gamma rays and ultraviolet light. The results of the gamma and UV experiments will be correlated with the tritium exposure results.« less

Electrical properties of III-Nitride LEDs: Recombination-based injection model and theoretical limits to electrical efficiency and electroluminescent cooling

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

David, Aurelien, E-mail: adavid@soraa.com; Hurni, Christophe A.; Young, Nathan G.

The current-voltage characteristic and ideality factor of III-Nitride quantum well light-emitting diodes (LEDs) grown on bulk GaN substrates are investigated. At operating temperature, these electrical properties exhibit a simple behavior. A model in which only active-region recombinations have a contribution to the LED current is found to account for experimental results. The limit of LED electrical efficiency is discussed based on the model and on thermodynamic arguments, and implications for electroluminescent cooling are examined.

A model for the scattering of high-frequency electromagnetic fields from dielectrics exhibiting thermally-activated electrical losses

NASA Technical Reports Server (NTRS)

Hann, Raiford E.

1991-01-01

An equivalent circuit model (ECM) approach is used to predict the scattering behavior of temperature-activated, electrically lossy dielectric layers. The total electrical response of the dielectric (relaxation + conductive) is given by the ECM and used in combination with transmission line theory to compute reflectance spectra for a Dallenbach layer configuration. The effects of thermally-activated relaxation processes on the scattering properties is discussed. Also, the effect of relaxation and conduction activation energy on the electrical properties of the dielectric is described.

Thermal-electrical properties and resistance stability of silver coated yarns

NASA Astrophysics Data System (ADS)

Li, Yafang; Liu, Hao; Li, Xiaojiu

2017-03-01

Thermal-electrical properties and resistance stability of silver yarns was researched to evaluate the performance be a heating element. Three samples of silver coated yarns with different linear density and electrical resistivity, which obtained by market. Silver coated yarns were placed at the high temperature condition for ageing. The electrical resistances of yarns were increased with the ageing process. The infrared photography instrument was used to measurement the temperature variation of silver coated yarns by applied different current on. The result shows that the temperature rise with the power increases.

Electrical Resistivity Measurements: a Review

NASA Astrophysics Data System (ADS)

Singh, Yadunath

World-wide interest on the use of ceramic materials for aerospace and other advanced engineering applications, has led to the need for inspection techniques capable of detecting unusually electrical and thermal anomalies in these compounds. Modern ceramic materials offer many attractive physical, electrical and mechanical properties for a wide and rapidly growing range of industrial applications; moreover specific use may be made of their electrical resistance, chemical resistance, and thermal barrier properties. In this review, we report the development and various techniques for the resistivity measurement of solid kind of samples.

Electric field effects on the optical properties of buckled GaAs monolayer

NASA Astrophysics Data System (ADS)

Bahuguna, Bhagwati Prasad; Saini, L. K.; Sharma, Rajesh O.

2018-04-01

Buckled GaAs monolayer has a direct band gap semiconductor with energy gap of 1.31 eV in the absence of electric field. When we applied transverse electric field, the value of band gap decreases with increasing of electric field strength. In our previous work [1], it is observed that the buckled GaAs monolayer becomes metallic at 1.3 V/Å. In the present work, we investigate the optical properties such as photon energy-dependent dielectric functions, extinction coefficient, refractive index, absorption spectrum and reflectivity of buckled GaAs monolayer in the semiconducting phase i.e. absence of external electric field and metallic phase i.e. presence of external electric field using density functional theory.

Electric field control of magnetic properties in FeRh/PMN-PT heterostructures

NASA Astrophysics Data System (ADS)

Xie, Yali; Zhan, Qingfeng; Shang, Tian; Yang, Huali; Liu, Yiwei; Wang, Baomin; Li, Run-Wei

2018-05-01

We investigated electric control of magnetic properties in FeRh/PMN-PT heterostructures. An electric field of 1 kV/cm applied on the PMN-PT substrate could increase the coercivity of FeRh film from 60 to 161 Oe at 360 K where the FeRh antiferromagnetic to ferromagnetic phase transition occurs. The electric field dependent coercive field reveals a butterfly shape, indicating a strain-mediated magnetoelectric coupling across the FeRh/PMN-PT interface. However, the uniaxial magnetic anisotropy of FeRh is almost unchanged with the applied electric field on the PMN-PT substrate, which suggests the change of coercivity in FeRh films is mainly due to the shift of the magnetic transition temperature under the electric field.

Variability analysis of the bulk resistivity measured using concrete cylinders.

DOT National Transportation Integrated Search

2011-01-01

"Many agencies are interested in using a rapid test method for measuring the electrical properties of concrete (i.e., the : resistivity or conductivity) since the electrical properties can be related to fluid transport (e.g., ion diffusion). The adva...

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.

CSI-EPT in Presence of RF-Shield for MR-Coils.

PubMed

Arduino, Alessandro; Zilberti, Luca; Chiampi, Mario; Bottauscio, Oriano

2017-07-01

Contrast source inversion electric properties tomography (CSI-EPT) is a recently developed technique for the electric properties tomography that recovers the electric properties distribution starting from measurements performed by magnetic resonance imaging scanners. This method is an optimal control approach based on the contrast source inversion technique, which distinguishes itself from other electric properties tomography techniques for its capability to recover also the local specific absorption rate distribution, essential for online dosimetry. Up to now, CSI-EPT has only been described in terms of integral equations, limiting its applicability to homogeneous unbounded background. In order to extend the method to the presence of a shield in the domain-as in the recurring case of shielded radio frequency coils-a more general formulation of CSI-EPT, based on a functional viewpoint, is introduced here. Two different implementations of CSI-EPT are proposed for a 2-D transverse magnetic model problem, one dealing with an unbounded domain and one considering the presence of a perfectly conductive shield. The two implementations are applied on the same virtual measurements obtained by numerically simulating a shielded radio frequency coil. The results are compared in terms of both electric properties recovery and local specific absorption rate estimate, in order to investigate the requirement of an accurate modeling of the underlying physical problem.

Studying Some of Electrical and Mechanical Properties for Kevlar Fiber Reinforced Epoxy

NASA Astrophysics Data System (ADS)

Rafeeq, Sewench N.; Hussein, Samah M.

2011-12-01

As ordinary known the ability of synthesizing electrical conducting polymer composites is possible but with poor mechanical properties, for the solution of this problem, we carried out this study in order to obtain that both properties. Three methods were applied for preparing the conductive polyaniline (PANI) composites using Kevlar fiber fabric as substrate for the deposition of the PANI at one time and the prepared composite (EP/Kevlar fiber) at others. The chemical oxidative method was adopted for polymerization of the aniline and simultaneously protonated of PANI with a hydrochloric acid at concentration (1M). Two kinds of oxidation agents (FeCl3.6H2O) and ((NH4)2S2O8) were used. The electrical measurements indicate the effect of each preparation method, kind of oxidant agent and the kind of mat erial which PANI deposited on the electrical results. The conductivity results showed that the prepared composites lie within semiconductors region. Temperature—dependence of electric conductivity results showed semiconductors and conductors behavior of this material within the applied temperature ranges. The mechan ical property (tensile strength) was studied. X-ray diffraction study showed the crystalline structure for EP/Kevlar fiber/PANI composites prepared by the three methods. These results gave optimism to the synthesis of conductive polymer composites with excellent mechanical properties..

Memristors in the electrical network of Aloe vera L.

PubMed Central

Volkov, Alexander G; Reedus, Jada; Mitchell, Colee M; Tucket, Clayton; Forde-Tuckett, Victoria; Volkova, Maya I; Markin, Vladislav S; Chua, Leon

2014-01-01

A memristor is a resistor with memory, which is a non-linear passive two-terminal electrical element relating magnetic flux linkage and electrical charge. Here we found that memristors exist in vivo. The electrostimulation of the Aloe vera by bipolar sinusoidal or triangle periodic waves induce electrical responses with fingerprints of memristors. Uncouplers carbonylcyanide-3-chlorophenylhydrazone and carbonylcyanide-4-trifluoromethoxy-phenyl hydrazone decrease the amplitude of electrical responses at low and high frequencies of bipolar periodic sinusoidal or triangle electrostimulating waves. Memristive behavior of an electrical network in the Aloe vera is linked to the properties of voltage gated ion channels: the K+ channel blocker TEACl reduces the electric response to a conventional resistor. Our results demonstrate that a voltage gated K+ channel in the excitable tissue of plants has properties of a memristor. The discovery of memristors in plants creates a new direction in the modeling and understanding of electrical phenomena in plants. PMID:25763487

Smart material-based radiation sources

NASA Astrophysics Data System (ADS)

Kovaleski, Scott

2014-10-01

From sensors to power harvesters, the unique properties of smart materials have been exploited in numerous ways to enable new applications and reduce the size of many useful devices. Smart materials are defined as materials whose properties can be changed in a controlled and often reversible fashion by use of external stimuli, such as electric and magnetic fields, temperature, or humidity. Smart materials have been used to make acceleration sensors that are ubiquitous in mobile phones, to make highly accurate frequency standards, to make unprecedentedly small actuators and motors, to seal and reduce friction of rotating shafts, and to generate power by conversion of either kinetic or thermal energy to electrical energy. The number of useful devices enabled by smart materials is large and continues to grow. Smart materials can also be used to generate plasmas and accelerate particles at small scales. The materials discussed in this talk are from non-centrosymmetric crystalline classes including piezoelectric, pyroelectric, and ferroelectric materials, which produce large electric fields in response to external stimuli such as applied electric fields or thermal energy. First, the use of ferroelectric, pyroelectric and piezoelectric materials for plasma generation and particle acceleration will be reviewed. The talk will then focus on the use of piezoelectric materials at the University of Missouri to construct plasma sources and electrostatic accelerators for applications including space propulsion, x-ray imaging, and neutron production. The basic concepts of piezoelectric transformers, which are analogous to conventional magnetic transformers, will be discussed, along with results from experiments over the last decade to produce micro-thrusters for space propulsion and particle accelerators for x-ray and neutron production. Support from ONR, AFOSR, and LANL.

Electric Field-Mediated Processing of Polymers. Appendix 1

NASA Technical Reports Server (NTRS)

Wnek, G. E.; Bowlin, G. L.; Haas, T. W.

2000-01-01

Significant opportunities exist for the processing of polymers (homopolymers and blends) using electric fields. We suggest that a broad range of properties can be achieved using a relatively small number of polymers, with electric fields providing the ability to tailor properties via the control of shape, morphology, and orientation. Specific attention is given to electrospinning, but we note that electroaerosol formation and field-modulated film casting represent additional processing options.

Method and apparatus for measuring properties of particle beams using thermo-resistive material properties

DOEpatents

Degtiarenko, Pavel V.; Dotson, Danny Wayne

2007-10-09

A beam position detector for measuring the properties of a charged particle beam, including the beam's position, size, shape, and intensity. One or more absorbers are constructed of thermo-resistive material and positioned to intercept and absorb a portion of the incoming beam power, thereby causing local heating of each absorber. The local temperature increase distribution across the absorber, or the distribution between different absorbers, will depend on the intensity, size, and position of the beam. The absorbers are constructed of a material having a strong dependence of electrical resistivity on temperature. The beam position detector has no moving parts in the vicinity of the beam and is especially suited to beam areas having high ionizing radiation dose rates or poor beam quality, including beams dispersed in the transverse direction and in their time radio frequency structure.

Periscopic Spine Surgery.

DTIC Science & Technology

2000-02-01

radiation medicine, the neurosurgery intensive care unit (ICU), and the pediatrics ICU [Geary 1999a]. The major procedures impacted are spine tumor...radiation medicine, and the pediatric intensive care unit . Hardware and software problems addressed included modifications of patient positioning...planning. Attempts have been made to link mechanical tissue properties to cellular interaction through electrical impedance [7] and to Hounsfield units

Mountain Plains Learning Experience Guide: Radio and T.V. Repair. Course: D.C. Circuits.

ERIC Educational Resources Information Center

Hoggatt, P.; And Others

One of four individualized courses included in a radio and television repair curriculum, this course deals with the basic electrical properties of current, voltage, resistance, magnetism, mutual induction, and capacitance. The course is comprised of ten units: (1) Current, (2) Voltage, (3) Resistance, (4) Measuring Voltage and Current in Series…

Electrically Reconfigurable Liquid Crystalline Mirrors (Postprint)

DTIC Science & Technology

2018-04-24

preparation of a structurally chiral polymer stabilizing network that enforces anchoring of a low-molar- mass liquid crystalline media with positive...crystals (LCs). The distinctive responses detailed here are enabled by the preparation of a structurally chiral polymer stabilizing network that enforces ...aerospace systems . Dynamic changes to optical material properties including absorption, diffraction, reflection, and scatter have been the subject to

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, H.L.; Kramer, S.A.; Spears, M.A.

1995-04-04

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided. 17 figures.

HAZARDS SUMMARY REPORT FOR A TWO WATT PROMETHIUM-147 FUELED THERMOELECTRIC GENERATOR

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

None

1959-06-01

Discussions are included of the APU design, vehicle integration, Pm/sup 147/ properties, shielding requirements, hazards design criteria, statistical analysis for impact, and radiation protection. The use of Pm/sup 147/ makes possible the fabrication of an auxiliary power unit which has applications for low power space missions of <10 watts (electrical). (B.O.G.)

Understanding the low temperature electrical properties of nanocrystalline tin oxide for gas sensor applications

NASA Astrophysics Data System (ADS)

Drake, Christina Hartsell

Nanocrystalline metal/metal oxide is an important class of transparent and electronic materials due to its potential use in many applications, including gas sensors. At the nanoscale, many of the phenomena observed that give nanocrystalline semiconducting oxide enhanced performance as a gas sensor material over other conventional engineering materials is still poorly understood. This study is aimed at understanding the low temperature electrical and chemical properties of nanocrystalline SnO2 that makes it suitable for room temperature gas detectors. Studies were carried out in order to understand how various synthesis methods affect the surfaces on the nano-oxides, interactions of a target gas (in this study hydrogen) with different surface species, and changes in the electrical properties as a function of dopants and grain size. A correlation between the surface reactions and the electrical response of doped nanocrystalline metal-oxide-semiconductors exposed to a reducing gas is established using Fourier Transform Infrared (FTIR) Spectroscopy attached to a specially built custom designed catalytic cell. First principle calculations of oxygen vacancy concentrations from absorbance spectra are presented. FTIR is used for effectively screening of these nanostructures for gas sensing applications. The effect of processing temperature on the microstructural evolution and on the electronic properties of nanocrystalline trivalent doped-SnO 2 is also presented. This study includes the effect of dopants (In and Ce) on the growth of nano-SnO2, as well as their effects on the electronic properties and gas sensor behavior of the nanomaterial at room temperature. Band bending affects are also investigated for this system and are related to enhanced low temperature gas sensing. The role and importance of oxygen vacancies in the electronic and chemical behavior of surface modified nanocrystalline SnO2 are explored in this study. A generalized explanation for the low temperature gas sensor behavior of nanocrystalline oxide is presented that can be generalized to other nano-oxide systems and be useful in specific engineering of other nanomaterials. Deeper understanding of how nano-oxides react chemically and electronically would be extremely beneficial to issues present in current low cost, low temperature sensor technology. Ability to exactly monitor and then engineer the chemistry of nanostructures in the space charge region as well as the surface is also of great significance. Knowledge of the mechanisms responsible for enhanced sensor response in this material system could viably be applied to other material systems for sensor applications.

Interesting properties of ferroelectric Pb(Zr0.5Ti0.5)O3 nanotube array embedded in matrix medium

NASA Astrophysics Data System (ADS)

Adhikari, Rajendra; Fu, Huaxiang

2013-07-01

Finite-temperature first-principles based simulations are used to determine the structural and polarization properties of ferroelectric Pb(Zr0.5Ti0.5)O3 (PZT) nanotube array embedded in matrix medium of different ferroelectric strengths. Various interesting properties are found, including (i) that the system can behave either 3D-like, or 2D-like, or 1D-like; and (ii) the existence of an unusual structural phase in which 180° stripe domain coexists with vortex. Furthermore, we show in PZT tube array that a vortex phase can spontaneously transform into a ferroelectric phase of polarization by temperature alone, without applying external electric fields. Microscopic insights for understanding these properties are provided.

Mechanochemical activation and patterning of an adhesive surface toward nanoparticle deposition.

PubMed

Baytekin, H Tarik; Baytekin, Bilge; Huda, Sabil; Yavuz, Zelal; Grzybowski, Bartosz A

2015-02-11

Mechanical pulling of adhesive tape creates radicals on the tape's surface. These radicals are capable of reducing metal salts to the corresponding metal nanoparticles. In this way, the mechanically activated tape can be decorated with various types of nanoparticles, including Au, Ag, Pd, or Cu. While retaining their mechanical properties and remaining "sticky," the tapes can exhibit new properties derived from the presence of metal nanoparticles (e.g., bacteriostaticity, increased electrical conductivity). They can also be patterned with nanoparticles only at selective locations of mechanical activation.

Electronic Chemical Potentials of Porous Metal–Organic Frameworks

PubMed Central

2014-01-01

The binding energy of an electron in a material is a fundamental characteristic, which determines a wealth of important chemical and physical properties. For metal–organic frameworks this quantity is hitherto unknown. We present a general approach for determining the vacuum level of porous metal–organic frameworks and apply it to obtain the first ionization energy for six prototype materials including zeolitic, covalent, and ionic frameworks. This approach for valence band alignment can explain observations relating to the electrochemical, optical, and electrical properties of porous frameworks. PMID:24447027

Characterization of real objects by an active electrolocation sensor

NASA Astrophysics Data System (ADS)

Metzen, Michael G.; Al Ghouz, Imène; Krueger, Sandra; Bousack, Herbert; von der Emde, Gerhard

2012-04-01

Weakly electric fish use a process called 'active electrolocation' to orientate in their environment and to localize objects based on their electrical properties. To do so, the fish discharge an electric organ which emits brief electrical current pulses (electric organ discharge, EOD) and in return sense the generated electric field which builds up surrounding the animal. Caused by the electrical properties of nearby objects, fish measure characteristic signal modulations with an array of electroreceptors in their skin. The fish are able to gain important information about the geometrical properties of an object as well as its complex impedance and its distance. Thus, active electrolocation is an interesting feature to be used in biomimetic approaches. We used this sensory principle to identify different insertions in the walls of Plexiglas tubes. The insertions tested were composed of aluminum, brass and graphite in sizes between 3 and 20 mm. A carrier signal was emitted and perceived with the poles of a commercial catheter for medical diagnostics. Measurements were performed with the poles separated by 6.3 to 55.3 mm. Depending on the length of the insertion in relation to the sender-receiver distance, we observed up to three peaks in the measured electric images. The first peak was affected by the material of the insertion, while the distance between the second and third peak strongly correlated with the length of the insertion. In a second experiment we tested whether various materials could be detected by using signals of different frequency compositions. Based on their electric images we were able to discriminate between objects having different resistive properties, but not between objects of complex impedances.

Molecular Clusters: Nanoscale Building Blocks for Solid-State Materials.

PubMed

Pinkard, Andrew; Champsaur, Anouck M; Roy, Xavier

2018-04-17

The programmed assembly of nanoscale building blocks into multicomponent hierarchical structures is a powerful strategy for the bottom-up construction of functional materials. To develop this concept, our team has explored the use of molecular clusters as superatomic building blocks to fabricate new classes of materials. The library of molecular clusters is rich with exciting properties, including diverse functionalization, redox activity, and magnetic ordering, so the resulting cluster-assembled solids, which we term superatomic crystals (SACs), hold the promise of high tunability, atomic precision, and robust architectures among a diverse range of other material properties. Molecular clusters have only seldom been used as precursors for functional materials. Our team has been at the forefront of new developments in this exciting research area, and this Account focuses on our progress toward designing materials from cluster-based precursors. In particular, this Account discusses (1) the design and synthesis of molecular cluster superatomic building blocks, (2) their self-assembly into SACs, and (3) their resulting collective properties. The set of molecular clusters discussed herein is diverse, with different cluster cores and ligand arrangements to create an impressive array of solids. The cluster cores include octahedral M 6 E 8 and cubane M 4 E 4 (M = metal; E = chalcogen), which are typically passivated by a shell of supporting ligands, a feature upon which we have expanded upon by designing and synthesizing more exotic ligands that can be used to direct solid-state assembly. Building from this library, we have designed whole families of binary SACs where the building blocks are held together through electrostatic, covalent, or van der Waals interactions. Using single-crystal X-ray diffraction (SCXRD) to determine the atomic structure, a remarkable range of compositional variability is accessible. We can also use this technique, in tandem with vibrational spectroscopy, to ascertain features about the constituent superatomic building blocks, such as the charge of the cluster cores, by analysis of bond distances from the SCXRD data. The combination of atomic precision and intercluster interactions in these SACs produces novel collective properties, including tunable electrical transport, crystalline thermal conductivity, and ferromagnetism. In addition, we have developed a synthetic strategy to insert redox-active guests into the superstructure of SACs via single-crystal-to-single-crystal intercalation. This intercalation process allows us to tune the optical and electrical transport properties of the superatomic crystal host. These properties are explored using a host of techniques, including Raman spectroscopy, SQUID magnetometry, electrical transport measurements, electronic absorption spectroscopy, differential scanning calorimetry, and frequency-domain thermoreflectance. Superatomic crystals have proven to be both robust and tunable, representing a new method of materials design and architecture. This Account demonstrates how precisely controlling the structure and properties of nanoscale building blocks is key in developing the next generation of functional materials; several examples are discussed and detailed herein.

Evolution of Mechanical and Electrical Properties During Annealing of the Copper Wire Drawn

NASA Astrophysics Data System (ADS)

Zidani, M.; Messaoudi, S.; Baudin, T.; Derfouf, C.; Boulagroun, A.; Mathon, M. H.

2011-12-01

In this work, the evolution of mechanical and electrical properties and microstructure of industrial copper wire used for electrical cabling was characterized. This work is not limited to the interpretation of the microstructural characteristics of the wire-drawn state but also after different annealing treatments. For the lowest temperatures (160 °C and 200 °C), significant changes are not observed in the microstructure (grain size) in the weak deformed wire (28.5%). Instead, variations of some properties of the metal were observed (hardness and electrical resistivity). For strong deformation (61.4% and 84.59%), annealing, leads to recrystallization with a softening material. Let us note that the resistivity increases with deformation level and becomes higher after annealing at low temperature (200 °C).

About the feasibilities of controlling the properties of thermoelectric energy converters using optical radiation

NASA Astrophysics Data System (ADS)

Kshevetsky, Oleg S.

2018-01-01

We represent evaluating analysis of the feasibilities for controlling the properties of thermoelectric energy converters using EM radiation in the regimes of cooling, heating, electromotive force generation, or electric current generation. Thus we investigate the influence of optical radiation both on electric conductivity and thermo-electromotive force coefficient of thermoelectric materials. We also discuss promising applications for controlling the properties of thermoelectric energy converters using EM radiation. We represent the results of experimental study of positionsensitive energy converters in the regimes of electromotive force generation and the electric current generation (in part, photo-thermoelectric position-sensitive temperature detectors), position-sensitive photo-thermoelectric energy converters in the regimes of cooling, heating, parallel photoelectric and thermoelectric conversion of sun-light optical radiation into electric power.

Materials characterization study of conductive flexible second surface mirrors

NASA Technical Reports Server (NTRS)

Levadou, F.; Bosma, S. J.; Paillous, A.

1981-01-01

The status of prequalification and qualification work on conductive flexible second surface mirrors is described. The basic material is FEP Teflon witn either aluminium or silver vacuum deposited reflectors. The top layer has been made conductive by deposition of layer of a indium oxide. The results of a prequalification program comprised of decontamination, humidity, thermal cycling, thermal shock and vibration tests are presented. Thermo-optical and electrical properties. The results of a prequalification program comprised of decontamination, humidity, thermal cycling, thermal shock and vibration tests are presented. Thermo-optical and electrical properties, the electrostatic behavior of the materials under simulated substorm environment and electrical conductivity at low temperatures are characterized. The effects of simulated ultra violet and particles irradiation on electrical and thermo-optical properties of the materials are also presented.

Synthesis and properties of the compound: LiNi 3/5Cu 2/5VO 4

NASA Astrophysics Data System (ADS)

Ram, Moti

2009-12-01

The LiNi 3/5Cu 2/5VO 4 is synthesized by solution-based chemical method and its formation has been checked by X-ray diffraction (XRD) study. XRD study shows a tetragonal unit cell structure with lattice parameters of a = 11.6475 (18) Å, c = 2.4855 (18) Å and c/ a = 0.2134 Å. Electrical properties are verified using complex impedance spectroscopy (CIS) technique. Complex impedance analysis reveals following points: (i) the bulk contribution to electrical properties up to 200 °C, (ii) the bulk and grain boundary contribution at T ≥ 225 °C, (iii) the presence of temperature dependent electrical relaxation phenomena in the material. D.c. conductivity study indicates that electrical conduction in the material is a thermally activated process.

Polythiophene-carbon nanotubes composites as energy storage materials for supercapacitor application

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

Thakur, A. K., E-mail: anukulphyism@gmail.com; Choudhary, R. B.; Sartale, S. D.

Polythiophene incorporated carbon materials have sought huge attention due to various improved electrochemical properties including enhanced electrical conductivity. Our work includes the synthesis of polythiophene (PTP)-multi-wallcarbon nanotubes (MWCNTs) via in-situ polymerization method. The homogeneous distribution of MWCNT in PTP was confirmed by Field Emission Scanning Electron Microscope (FESEM). Examination of the specimen using X-Ray diffraction (XRD), Fourier Transform-Infrared (FTIR) and Raman spectroscopy confirmed the composite formation. Other electrochemical characterizations like electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV)of the PTP-MWCNT composite affirmed that incorporation of MWCNT improves the electrochemical properties of neat PTP including a significant increase in the capacitance.more » Hence making PTP-MWCNT isa better material for supercapacitor application than neat PTP.« less

Characterization of Photovoltaic Generators

ERIC Educational Resources Information Center

Boitier, V.; Cressault, Y.

2011-01-01

This paper discusses photovoltaic panel systems and reviews their electrical properties and use in several industrial fields. We explain how different photovoltaic panels may be characterized by undergraduate students at university using simple methods to retrieve their electrical properties (power, current and voltage) and compare these values…

Improving our understanding of hydraulic-electrical relations: A case study of the surficial aquifer in Emirate Abu Dhabi

USGS Publications Warehouse

Ikard, Scott; Kress, Wade

2016-01-01

Transmissivity is a bulk hydraulic property that can be correlated with bulk electrical properties of an aquifer. In aquifers that are electrically-resistive relative to adjacent layers in a horizontally stratified sequence, transmissivity has been shown to correlate with bulk transverse resistance. Conversely, in aquifers that are electrically-conductive relative to adjacent layers, transmissivity has been shown to correlate with bulk longitudinal conductance. In both cases, previous investigations have relied on small datasets (on average less than eight observations) that have yielded coefficients of determination (R2) that are typically in the range of 0.6 to 0.7 to substantiate these relations. Compared to previous investigations, this paper explores hydraulic-electrical relations using a much larger dataset. Geophysical data collected from 26 boreholes in Emirate Abu Dhabi, United Arab Emirates, are used to correlate transmissivity modeled from neutron porosity logs to the bulk electrical properties of the surficial aquifer that are computed from deep-induction logs. Transmissivity is found to be highly correlated with longitudinal conductance. An R2 value of 0.853 is obtained when electrical effects caused by variations in pore-fluid salinity are taken into consideration.

Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields

NASA Technical Reports Server (NTRS)

Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.

The Role of Interfaces in Polyethylene/Metal-Oxide Nanocomposites for Ultrahigh-Voltage Insulating Materials.

PubMed

Pourrahimi, Amir Masoud; Olsson, Richard T; Hedenqvist, Mikael S

2018-01-01

Recent progress in the development of polyethylene/metal-oxide nanocomposites for extruded high-voltage direct-current (HVDC) cables with ultrahigh electric insulation properties is presented. This is a promising technology with the potential of raising the upper voltage limit in today's underground/submarine cables, based on pristine polyethylene, to levels where the loss of energy during electric power transmission becomes low enough to ensure intercontinental electric power transmission. The development of HVDC insulating materials together with the impact of the interface between the particles and the polymer on the nanocomposites electric properties are shown. Important parameters from the atomic to the microlevel, such as interfacial chemistry, interfacial area, and degree of particle dispersion/aggregation, are discussed. This work is placed in perspective with important work by others, and suggested mechanisms for improved insulation using nanoparticles, such as increased charge trap density, adsorption of impurities/ions, and induced particle dipole moments are considered. The effects of the nanoparticles and of their interfacial structures on the mechanical properties and the implications of cavitation on the electric properties are also discussed. Although the main interest in improving the properties of insulating polymers has been on the use of nanoparticles, leading to nanodielectrics, it is pointed out here that larger microscopic hierarchical metal-oxide particles with high surface porosity also impart good insulation properties. The impact of the type of particle and its inherent properties (purity and conductivity) on the nanocomposite dielectric and insulating properties are also discussed based on data obtained by a newly developed technique to directly observe the charge distribution on a nanometer scale in the nanocomposite. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evolution of Structural and Electrical Properties of Carbon Films from Amorphous Carbon to Nanocrystalline Graphene on Quartz Glass by HFCVD.

PubMed

Zhai, Zihao; Shen, Honglie; Chen, Jieyi; Li, Xuemei; Jiang, Ye

2018-05-23

Direct growth of graphene films on glass is of great importance but has so far met with limited success. The noncatalytic property of glass results in the low decomposition ability of hydrocarbon precursors, especially at reduced temperatures (<1000 °C), and therefore amorphous carbon (a-C) films are more likely to be obtained. Here, we report the hydrogen influence on the structural and electrical properties of carbon films deposited on quartz glass at 850 °C by hot-filament chemical vapor deposition (HFCVD). The results revealed that the obtained a-C films were all graphitelike carbon films. Structural transition of the deposited films from a-C to nanocrystalline graphene was achieved by raising the hydrogen dilution ratios from 10 to over 80%. On the basis of systematic structural and chemical characterizations, a schematic process with three steps including sp 2 chain aggregation, aromatic ring formation, and sp 3 bond etching was proposed to interpret the structural evolution. The nanocrystalline graphene films grown on glass by HFCVD exhibited good electrical performance with a carrier mobility of 36.76 cm 2 /(V s) and a resistivity of 5.24 × 10 -3 Ω cm over an area of 1 cm 2 . Temperature-dependent electrical characterizations revealed that the electronic transport in carbon films was dominated by defect, localized, and extended states, respectively, when increasing the temperature from 75 to 292 K. The nanocrystalline graphene films presented higher carrier mobility and lower carrier concentration than those of a-C films, which was mainly attributed to their smaller conductive activation energy. The present investigation provides an effective way for direct growth of graphene films on glass at reduced temperatures and also offers useful insights into the understanding of structural and electrical relationship between a-C and graphene.

Enhancing Optical and Electrical Properties of La- and Al-Codoped ZnO Thin Films Prepared by Sol-Gel Method -La Codoping Effect.

PubMed

He-Yan, Hai

2017-07-10

Backgroud: The transparent conductive ZnO film is widely used in solar cell. Enhancing the transmittance and electrical conductivity of the films is attracting many attentions to improve cell efficiency. This work focuses on the fabrication and potential application of the various cation-doped ZnO materials in recent patents and literature and then presents the La codoping effects of Al-doped ZnO films. Films were deposited by a sol-gel route and characterized by various techniques including X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, UV-vis and luminescent spectroscopies, and electrical conduction analysis. The UV-vis. transmittance and band gap increased and then decreased, whereas the resistivity decreased and then slightly increased with the increase in La/Al ratio. The La/Al ratio of 0.0105 led to a maximal transmittance, a widest band gap, and a minimal resistivity. The films also illustrated a near band gap emission and some intrinsic defect-related emissions with varied intensity with La/Al ratio. This work reveal that the electrical and optical properties of the ZnO:Al films can be well enhanced by La codoping. This is significant to the applications of the ZnO:Al materials. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Fabrication and characterization of vertically aligned carbon-nanotube membranes

NASA Astrophysics Data System (ADS)

Castellano, Richard; Akin, Cevat; Purri, Matt; Shan, Jerry; Kim, Sangil; Fornasiero, Francesco

2015-11-01

Membranes having vertically-aligned carbon-nanotube (VACNT) pores offer promise as highly efficient and permeable membranes for use as breathable thin films, or in filtration and separation applications, among others. However, current membrane-fabrication techniques utilizing chemical-vapor-deposition-grown VACNT arrays are costly and difficult to scale up. We have developed a solution-based, electric-field-assisted approach as a cost-effective and scalable method to produce large-area VACNT membranes. Nanotubes are dispersed in a liquid polymer, and aligned and electrodeposited with the aid of an electric field prior to crosslinking the polymer to create VACNT membranes. We experimentally examine the electrodeposition process, focusing on parameters including the electric field, composition of the solution, and CNT functionalization that can affect the nanotube number density in the resulting membrane. We characterize the CNT pore size and number density and investigate the transport properties of the membrane. Size-exclusion tests are used to check for defects and infer the pore size of the VACNT membranes. Dry-gas membrane permeability is measured with a pressurized nitrogen-flow system, while moisture-vapor-transfer rate is measured with the ASTM-E96 upright-cup test. We discuss the measured transport properties of the solution-based, electric-field-fabricated VACNT membranes in reference to their application as breathable thin films. We would like to acknowledge DTRA for their funding and support of our research.

Electrical property sensing biopsy needle for prostate cancer detection.

PubMed

Mishra, V; Schned, A R; Hartov, A; Heaney, J A; Seigne, J; Halter, R J

2013-11-01

Significant electrical property differences have been demonstrated to exist between malignant and benign prostate tissues. We evaluated how well a custom designed clinically deployable electrical property sensing biopsy needle is able to discriminate between these tissue types in an ex vivo prostate model. An electrical impedance spectroscopy (EIS) sensing biopsy (Bx) needle was developed to record resistive (ρR) and reactive (ρX) components of electrical impedance from 100 Hz to 1 MHz. Standard twelve-core biopsy protocols were followed, in which the EIS-Bx device was used to gauge electrical properties prior to extracting tissue cores through biopsy needle firing from 36 ex vivo human prostates. Histopathological assessment of the cores was statistically compared to the impedance spectrum gauged from each core. The magnitudes of the mean resistive and reactive components were significantly higher in cancer tissues (P < 0.05). ROC curves showed that ρR at 63.09 kHz was optimal for discriminating cancer from benign tissues; this parameter had 75.4% specificity, 76.1% sensitivity, and ROC AUC of 0.779. Similarly, 251.1 kHz was optimal when using ρX to discriminate cancer from benign tissues; this parameter had a 77.9% specificity, 71.4% sensitivity, and ROC AUC of 0.79. Significant electrical property differences noted between benign and malignant prostate tissues suggest the potential efficacy an EIS-Bx device would provide for cancer detection in a clinical setting. By sensing a greater fraction of the prostate's volume in real-time, the EIS-Bx device has the potential to improve the accuracy of cancer grading and volume estimation made with current biopsy procedures. © 2013 Wiley Periodicals, Inc.

Aerial Transient Electromagnetic Surveys of Alluvial Aquifers in Rural Watersheds of Arizona

NASA Astrophysics Data System (ADS)

Pool, D. R.; Callegary, J. B.; Groom, R. W.

2006-12-01

Development in rural areas of Arizona has led the State of Arizona (Arizona Department of Water Resources), in cooperation with the Arizona Water Science Center of the U.S. Geological Survey, to sponsor investigations of the hydrogeologic framework of several alluvial-basin aquifers. An efficient method for mapping the aquifer extent and lithology was needed due to sparse subsurface information. Aerial Transient Electro-Magnetic (ATEM) methods were selected because they can be used to quickly survey large areas and with a great depth of investigation. Both helicopter and fixed-wing ATEM methods are available. A fixed-wing method (GEOTEM) was selected because of the potential for a depth of investigation of 300 m or more and because previous surveys indicated the method is useful in alluvial basins in southeastern Arizona. About 2,900 km of data along flight lines were surveyed across five alluvial basins, including the Middle San Pedro and Willcox Basins in southeastern Arizona, and Detrital, Hualapai, and Sacramento Basins in northwestern Arizona. Data initially were analyzed by the contractor (FUGRO Airborne Surveys) to produce conductivity-depth-transforms, which approximate the general subsurface electrical-property distribution along profiles. Physically based two-dimensional physical models of the profile data were then developed by PetRos- Eikon by using EMIGMA software. Hydrologically important lithologies can have different electrical properties. Several types of crystalline and sedimentary rocks generally are poor aquifers that have low porosity and high electrical resistivity. Good alluvial aquifers of sand and gravel generally have an intermediate electrical resistivity. Poor aquifer materials, such as silt and clay, and areas of poor quality water have low electrical resistivity values. Several types of control data were available to constrain the models including drill logs, electrical logs, water levels , and water quality information from wells; and gravity, seismic, direct-current resistivity, and transient-electromagnetic information from ground-based geophysical surveys. Results of the surveys will be used along with available subsurface information to describe the spatial extent of the alluvial aquifers and the general lithologic distribution within the alluvial aquifers.

Thermoelectric transport properties of BaBiTe{sub 3}-based materials

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

Zhou, Yiming; Zhao, Li-Dong, E-mail: zhaolidong@buaa.edu.cn

BaBiTe{sub 3}, a material with low thermal conductivity, is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. We choose two types of dopants, K and La, trying to optimize its electrical transport properties. The minority carriers, which harm the Seebeck coefficient in this system, are suppressed by La doping. With the increase of both electrical conductivity and Seebeck coefficient, the power factor of 3% La doped BaBiTe{sub 3} reaches 3.7 μW cm{sup −1} K{sup −2} which increased by 40% from undoped BaBiTe{sub 3}. Besides high power factor, the thermal conductivity is alsomore » reduced in it. Eventually, a high ZT value, 0.25 at 473 K, for n-type BaBiTe{sub 3} is achieved in 3% La doped BaBiTe{sub 3}. - Graphical abstract: BaBiTe{sub 3} possesses a low thermal conductivity. However, it is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. A high ZT value of 0.25 at 473 K for n-type BaBiTe{sub 3} can be achieved through optimizing electrical transport properties via La doping. - Highlights: • BaBiTe{sub 3} is an analogue of these promising thermoelectric materials: such as CsBi{sub 4}Te{sub 6} and K{sub 2}Bi{sub 8}Se{sub 13}, etc. • BaBiTe{sub 3} possesses a low thermal conductivity. • La is an effective dopant to enhance electrical transport properties. • A high ZT value of 0.25 at 473 K can be achieved in n-type La-doped BaBiTe{sub 3}.« less

Effects of sulfurization time and H{sub 2}S concentration on electrical properties of Cu{sub 2}ZnSnS{sub 4} films prepared by sol–gel method

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

Long, Bo; Cheng, Shuying, E-mail: sycheng@fzu.edu.cn; Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou 213164

2016-01-15

Highlights: • Cu{sub 2}ZnSnS{sub 4} (CZTS) films were prepared by sol–gel method following sulfurization. • The sulfurization time and H{sub 2}S concentration have the effects on the electrical properties. • The tin loss is increased with the increasing of the sulfurization time. • The secondary phases like ZnS make the electrical properties worse. • The CZTS films sulfurized at 5% H{sub 2}S for 90 min had the best electrical properties. - Abstract: Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films have been successfully deposited by a sol–gel method and sulfurization process. The properties of the films were investigated by varying sulfurization timemore » and H{sub 2}S concentration. X-ray diffraction and Raman spectra analyses revealed the formation of CZTS films with a tetragonal type kesterite structure. With increasing the sulfurization time and H{sub 2}S concentration, the intensity of the kesterite (1 1 2) peak became sharper. The stoichiometric ratios of the CZTS films were different from the precursors, which was due to Sn loss during the sulfurization process. The electrical resistivity and mobility of the films increased while the carrier concentration decreased with increasing the sulfurization time. The CZTS thin films sulfurized at 5% H{sub 2}S concentration for 90 min had the best opto-electrical properties with E{sub g} of 1.41 eV, resistivity of 3.64 Ω cm, carrier concentration of 1.11 × 10{sup 18} cm{sup −3} and mobility of 1.54 cm{sup 2}/(V s) at room temperature for PV application.« less

National Electrical Code in Power Engineering Course for Electrical Engineering Curriculum

ERIC Educational Resources Information Center

Azizur, Rahman M. M.

2011-01-01

In order to ensure the safety of their inhabitants and properties, the residential, industrial and business installations require complying with NEC (national electrical code) for electrical systems. Electrical design engineers and technicians rely heavily on these very important design guidelines. However, these design guidelines are not formally…

On the modeling and characterization of an interlocked flexible electronic skin

NASA Astrophysics Data System (ADS)

Khalili, Nazanin; Shen, Xuechen; Naguib, Hani E.

2017-04-01

Development of an electronic skin with ultra-high pressure sensitivity is now of critical importance due its broad range of applications including prosthetic skins and biomimetic robotics. Microstructured conductive composite elastomers can acquire mechanical and electrical properties analogous to those of natural skin. One of the most prominent features of human skin is its tactile sensing property which can be mimicked in an electronic skin. Herein, an electrically conductive composite comprising polydimethylsiloxane and conductive fillers is used as a flexible and stretchable piezoresistive sensor. The electrical conductivity is induced within the elastomer matrix via carbon nanotubes whereas the piezoresistivity is obtained by means of microstructuring the surface of the substrate. An interlocked array of pyramids in micro-scale allows the change in the contact resistance between two thin layers of the composite upon application of an external load. Deformation of the interlocked arrays endows the sensor with an ultra-high sensitivity to the external pressures within the range of human skin perception. Moreover, using finite element analysis, the change in the contact are between the two layers was captured for different geometries. The structure of the sensor can be optimized through an optimization model in order to acquire maximum sensitivity.

Electrical percolation threshold of cementitious composites possessing self-sensing functionality incorporating different carbon-based materials

NASA Astrophysics Data System (ADS)

Al-Dahawi, Ali; Haroon Sarwary, Mohammad; Öztürk, Oğuzhan; Yıldırım, Gürkan; Akın, Arife; Şahmaran, Mustafa; Lachemi, Mohamed

2016-10-01

An experimental study was carried out to understand the electrical percolation thresholds of different carbon-based nano- and micro-scale materials in cementitious composites. Multi-walled carbon nanotubes (CNTs), graphene nanoplatelets (GNPs) and carbon black (CB) were selected as the nano-scale materials, while 6 and 12 mm long carbon fibers (CF6 and CF12) were used as the micro-scale carbon-based materials. After determining the percolation thresholds of different electrical conductive materials, mechanical properties and piezoresistive properties of specimens produced with the abovementioned conductive materials at percolation threshold were investigated under uniaxial compressive loading. Results demonstrate that regardless of initial curing age, the percolation thresholds of CNT, GNP, CB and CFs in ECC mortar specimens were around 0.55%, 2.00%, 2.00% and 1.00%, respectively. Including different carbon-based conductive materials did not harm compressive strength results; on the contrary, it improved overall values. All cementitious composites produced with carbon-based materials, with the exception of the control mixtures, exhibited piezoresistive behavior under compression, which is crucial for sensing capability. It is believed that incorporating the sensing attribute into cementitious composites will enhance benefits for sustainable civil infrastructures.

Influence of Ga-concentration on the electrical and magnetic properties of magnetoelectric CoGa xFe 2–xO 4/BaTiO 3 composite

DOE PAGES

Ni, Yan; Zhang, Zhen; Nlebedim, Cajetan I.; ...

2015-03-20

Multiferroic materials exhibit magnetoelectric (ME) coupling and promise new device applications including magnetic sensors, generators, and filters. An effective method for developing ME materials with enhanced ME effect is achieved by the coupling through the interfacial strain between piezoelectric and magnetostrictive materials. In this study, the electrical and magnetic properties of Ga doped magnetoelectric CoGa xFe 2–xO 4/BaTiO 3 composite are studied systematically. It is found that Ga doping improves the sensitivity of magnetoelastic response and stabilizes the magnetic phase of the composites. More importantly, Ga doping reduces the electrical conductivity of composite, as well as the dielectric loss. Anmore » enhancement of the electrostrain with doping Ga is also observed. Quantitative estimation indicates that magnetoelectric coupling is enhanced for Ga-doped CoGa xFe 2–xO 4/BaTiO 3 composites. As a result, the present work is beneficial to the practical application of composite CoFe 2O 4/BaTiO 3-based multiferroic materials.« less

A Direct Method to Extract Transient Sub-Gap Density of State (DOS) Based on Dual Gate Pulse Spectroscopy

NASA Astrophysics Data System (ADS)

Dai, Mingzhi; Khan, Karim; Zhang, Shengnan; Jiang, Kemin; Zhang, Xingye; Wang, Weiliang; Liang, Lingyan; Cao, Hongtao; Wang, Pengjun; Wang, Peng; Miao, Lijing; Qin, Haiming; Jiang, Jun; Xue, Lixin; Chu, Junhao

2016-06-01

Sub-gap density of states (DOS) is a key parameter to impact the electrical characteristics of semiconductor materials-based transistors in integrated circuits. Previously, spectroscopy methodologies for DOS extractions include the static methods, temperature dependent spectroscopy and photonic spectroscopy. However, they might involve lots of assumptions, calculations, temperature or optical impacts into the intrinsic distribution of DOS along the bandgap of the materials. A direct and simpler method is developed to extract the DOS distribution from amorphous oxide-based thin-film transistors (TFTs) based on Dual gate pulse spectroscopy (GPS), introducing less extrinsic factors such as temperature and laborious numerical mathematical analysis than conventional methods. From this direct measurement, the sub-gap DOS distribution shows a peak value on the band-gap edge and in the order of 1017-1021/(cm3·eV), which is consistent with the previous results. The results could be described with the model involving both Gaussian and exponential components. This tool is useful as a diagnostics for the electrical properties of oxide materials and this study will benefit their modeling and improvement of the electrical properties and thus broaden their applications.

The potential of magneto-electric nanocarriers for drug delivery.

PubMed

Kaushik, Ajeet; Jayant, Rahul Dev; Sagar, Vidya; Nair, Madhavan

2014-10-01

The development and design of personalized nanomedicine for better health quality is receiving great attention. In order to deliver and release a therapeutic concentration at the target site, novel nanocarriers (NCs) were designed, for example, magneto-electric (ME) which possess ideal properties of high drug loading, site-specificity and precise on-demand controlled drug delivery. This review explores the potential of ME-NCs for on-demand and site-specific drug delivery and release for personalized therapeutics. The main features including effect of magnetism, improvement in drug loading, drug transport across blood-brain barriers and on-demand controlled release are also discussed. The future directions and possible impacts on upcoming nanomedicine are highlighted. Numerous reports suggest that there is an urgent need to explore novel NC formulations for safe and targeted drug delivery and release at specific disease sites. The challenges of formulation lie in the development of NCs that improve biocompatibility and surface modifications for optimum drug loading/preservation/transmigration and tailoring of electrical-magnetic properties for on-demand drug release. Thus, the development of novel NCs is anticipated to overcome the problems of targeted delivery of therapeutic agents with desired precision that may lead to better patient compliance.

Graphene in biomedicine: opportunities and challenges.

PubMed

Feng, Liangzhu; Liu, Zhuang

2011-02-01

Graphene, whose discovery won the 2010 Nobel Prize in physics, has been a shining star in the material science in the past few years. Owing to its interesting electrical, optical, mechanical and chemical properties, graphene has found potential applications in a wide range of areas, including biomedicine. In this article, we will summarize the latest progress of using graphene for various biomedical applications, including drug delivery, cancer therapies and biosensing, and discuss the opportunities and challenges in this emerging field.

Comprehension of the Electric Polarization as a Function of Low Temperature

NASA Astrophysics Data System (ADS)

Liu, Changshi

2017-01-01

Polarization response to warming plays an increasingly important role in a number of ferroelectric memory devices. This paper reports on the theoretical explanation of the relationship between polarization and temperature. According to the Fermi-Dirac distribution, the basic property of electric polarization response to temperature in magnetoelectric multiferroic materials is theoretically analyzed. The polarization in magnetoelectric multiferroic materials can be calculated by low temperature using a phenomenological theory suggested in this paper. Simulation results revealed that the numerically calculated results are in good agreement with experimental results of some inhomogeneous multiferroic materials. Numerical simulations have been performed to investigate the influences of both electric and magnetic fields on the polarization in magnetoelectric multiferroic materials. Furthermore, polarization behavior of magnetoelectric multiferroic materials can be predicted by low temperature, electric field and magnetic induction using only one function. The calculations offer an insight into the understanding of the effects of heating and magnetoelectric field on electrical properties of multiferroic materials and offer a potential to use similar methods to analyze electrical properties of other memory devices.

Specialized mechanical properties of pure aluminum by using non-equal channel angular pressing for developing its electrical applications

NASA Astrophysics Data System (ADS)

Fereshteh-Saniee, Faramarz; Asgari, Mohammad; Fakhar, Naeimeh

2016-08-01

Despite valuable electrical characteristics, the use of pure aluminum in different applications has been limited due to its low strength. Non-equal channel angular pressing (NECAP) is a recently proposed severe plastic deformation process with greater induced plastic strain and, consequently, better grain refinement in the product, compared with the well-known equal channel angular pressing technique. This research is concerned with the effects of the process temperature and ram velocity on the mechanical, workability and electrical properties of AA1060 aluminum alloy. Increasing the process temperature can concurrently increase the workability, ductility and electrical conductivity, while it has a reverse influence on the strength of the NECAPed specimen, although the strengths of all the products are higher than the as-received alloy. The influence of the ram speed on the mechanical properties of the processed samples is lower than the process temperature. Finally, a compromised process condition is introduced in order to attain a good combination of workability and strength with well-preserved electrical conductivity for electrical applications of components made of pure aluminum.

Aggregate nanostructures of organic molecular materials.

PubMed

Liu, Huibiao; Xu, Jialiang; Li, Yongjun; Li, Yuliang

2010-12-21

Conjugated organic molecules are interesting materials because of their structures and their electronic, electrical, magnetic, optical, biological, and chemical properties. However, researchers continue to face great challenges in the construction of well-defined organic compounds that aggregate into larger molecular materials such as nanowires, tubes, rods, particles, walls, films, and other structural arrays. Such nanoscale materials could serve as direct device components. In this Account, we describe our recent progress in the construction of nanostructures formed through the aggregation of organic conjugated molecules and in the investigation of the optical, electrical, and electronic properties that depend on the size or morphology of these nanostructures. We have designed and synthesized functional conjugated organic molecules with structural features that favor assembly into aggregate nanostructures via weak intermolecular interactions. These large-area ordered molecular aggregate nanostructures are based on a variety of simpler structures such as fullerenes, perylenes, anthracenes, porphyrins, polydiacetylenes, and their derivatives. We have developed new methods to construct these larger structures including organic vapor-solid phase reaction, natural growth, association via self-polymerization and self-organization, and a combination of self-assembly and electrochemical growth. These methods are both facile and reliable, allowing us to produce ordered and aligned aggregate nanostructures, such as large-area arrays of nanowires, nanorods, and nanotubes. In addition, we can synthesize nanoscale materials with controlled properties. Large-area ordered aggregate nanostructures exhibit interesting electrical, optical, and optoelectronic properties. We also describe the preparation of large-area aggregate nanostructures of charge transfer (CT) complexes using an organic solid-phase reaction technique. By this process, we can finely control the morphologies and sizes of the organic nanostructures on wires, tubes, and rods. Through field emission studies, we demonstrate that the films made from arrays of CT complexes are a new kind of cathode materials, and we systematically investigate the effects of size and morphology on electrical properties. Low-dimension organic/inorganic hybrid nanostructures can be used to produce new classes of organic/inorganic solid materials with properties that are not observed in either the individual nanosize components or the larger bulk materials. We developed the combined self-assembly and templating technique to construct various nanostructured arrays of organic and inorganic semiconductors. The combination of hybrid aggregate nanostructures displays distinct optical and electrical properties compared with their individual components. Such hybrid structures show promise for applications in electronics, optics, photovoltaic cells, and biology. In this Account, we aim to provide an intuition for understanding the structure-function relationships in organic molecular materials. Such principles could lead to new design concepts for the development of new nonhazardous, high-performance molecular materials on aggregate nanostructures.