Electrically Conductive Anodized Aluminum Surfaces

Science.gov (United States)

Nguyen, Trung Hung

2006-01-01

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

Calibration-free electrical conductivity measurements for highly conductive slags

International Nuclear Information System (INIS)

Macdonald, Christopher J.; Gao, Huang; Pal, Uday B.; Van den Avyle, James A.; Melgaard, David K.

2000-01-01

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

Computation of radiation from wire antennas on conducting bodies

DEFF Research Database (Denmark)

Albertsen, N. Christian; Hansen, Jesper; Jensen, Niels E.

1974-01-01

A theoretical formulation, in terms of combined magnetic and electric field integral equations, is presented for the class of electromagnetic problems in which one or more wire antennas are connected to a conducting body of arbitrary shape. The formulation is suitable for numerical computation...... provided that the overall dimensions of the structure are not large compared to the wavelength. A computer program is described, and test runs on various configurations involving a cylindrical body with one or more straight wires are presented. The results obtained agree well with experimental data....

Electrically conductive composite material

Science.gov (United States)

Clough, Roger L.; Sylwester, Alan P.

1989-01-01

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

Determination of electrical characteristics of body tissues for computational dosimetry studies

International Nuclear Information System (INIS)

Silva, Rafael Monteiro da Cruz; Domingues, Luis Adriano M.C.; Neto, Athanasio Mpalantinos; Barbosa, Carlos Ruy Nunez

2008-01-01

Increasing public concern about human exposure to electromagnetic fields led to the development of International Exposure Standards, which reflect the actual scientific knowledge on this subject. Existing exposure limits (reference levels), are based on maximum admissible fields or induced currents densities inside human bodies, called basic restrictions. Since those physical quantities can not be readily measured, they must be estimated using techniques of computational dosimetry. These techniques rely on accurate computational modelling of human bodies to establish the relation of external field (electric / magnetic) to induced current (internal field). Nowadays the models available for human body simulation (FEM, FDM,...) are quite accurate, specially when using geometric discretization obtained from medical imaging techniques, however the determination of tissues characteristics (permittivity and conductivity) is still an issue to be dealt with. In current studies the electrical characteristics (permittivity and conductivity) of body tissues are based on values which were obtained from measurements done on tissue simples obtained from dead bodies. However those values may not represent adequately the behaviour of living tissues. In this paper a research designed to characterize the permittivity of human body tissues is presented, consisting of measurements and simulations designed to determine, using indirect methods, the electrical behaviour of living tissues. A study of exposure assessment on a real high voltage transmission line in Brazil, using measured permittivity values combined with a finite element model of the human body is presented in the panel. (author)

Electrical Conductivity Distributions in Discrete Fluid-Filled Fractures

Science.gov (United States)

James, S. C.; Ahmmed, B.; Knox, H. A.; Johnson, T.; Dunbar, J. A.

2017-12-01

It is commonly asserted that hydraulic fracturing enhances permeability by generating new fractures in the reservoir. Furthermore, it is assumed that in the fractured system predominant flow occurs in these newly formed and pre-existing fractures. Among the phenomenology that remains enigmatic are fluid distributions inside fractures. Therefore, determining fluid distribution and their associated temporal and spatial evolution in fractures is critical for safe and efficient hydraulic fracturing. Previous studies have used both forward modeling and inversion of electrical data to show that a geologic system consisting of fluid filled fractures has a conductivity distribution, where fractures act as electrically conductive bodies when the fluids are more conductive than the host material. We will use electrical inversion for estimating electrical conductivity distribution within multiple fractures from synthetic and measured data. Specifically, we will use data and well geometries from an experiment performed at Blue Canyon Dome in Socorro, NM, which was used as a study site for subsurface technology, engineering, and research (SubTER) funded by DOE. This project used a central borehole for energetically stimulating the system and four monitoring boreholes, emplaced in the cardinal directions. The electrical data taken during this project used 16 temporary electrodes deployed in the stimulation borehole and 64 permanent electrodes in the monitoring wells (16 each). We present results derived using E4D from scenarios with two discrete fractures, thereby discovering the electric potential response of both spatially and temporarily variant fluid distribution and the resolution of fluid and fracture boundaries. These two fractures have dimensions of 3m × 0.01m × 7m and are separated by 1m. These results can be used to develop stimulation and flow tests at the meso-scale that will be important for model validation. Sandia National Laboratories is a multi

Electrically conductive anodized aluminum coatings

Science.gov (United States)

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

2001-01-01

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

Total body irradiation

International Nuclear Information System (INIS)

Novack, D.H.; Kiley, J.P.

1987-01-01

The multitude of papers and conferences in recent years on the use of very large megavoltage radiation fields indicates an increased interest in total body, hemibody, and total nodal radiotherapy for various clinical situations. These include high dose total body irradiation (TBI) to destroy the bone marrow and leukemic cells and provide immunosuppression prior to a bone marrow transplant, high dose total lymphoid irradiation (TLI) prior to bone marrow transplantation in severe aplastic anemia, low dose TBI in the treatment of lymphocytic leukemias or lymphomas, and hemibody irradiation (HBI) in the treatment of advanced multiple myeloma. Although accurate provision of a specific dose and the desired degree of dose homogeneity are two of the physicist's major considerations for all radiotherapy techniques, these tasks are even more demanding for large field radiotherapy. Because most large field radiotherapy is done at an extended distance for complex patient geometries, basic dosimetry data measured at the standard distance (isocenter) must be verified or supplemented. This paper discusses some of the special dosimetric problems of large field radiotherapy, with specific examples given of the dosimetry of the TBI program for bone marrow transplant at the authors' hospital

Nonideal ultrathin mantle cloak for electrically large conducting cylinders.

Science.gov (United States)

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

2014-09-01

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

Electrical conductivity of conductive carbon blacks: influence of surface chemistry and topology

International Nuclear Information System (INIS)

Pantea, Dana; Darmstadt, Hans; Kaliaguine, Serge; Roy, Christian

2003-01-01

Conductive carbon blacks from different manufacturers were studied in order to obtain some insight into the relation between their electrical conductivity and their surface properties. The surface chemistry was studied by X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (SIMS), whereas the topology of the carbon black surface was investigated using low-pressure nitrogen adsorption. All these techniques yield information on the graphitic character of the surface. In general, the electrical conductivity of the conductive blacks increases with the graphitic character of the surface. For low surface area conductive blacks, the electrical conductivity correlates well with the surface chemistry. In the case of the XPS and SIMS data, this correlation is also valid when other types of carbon blacks such as thermal and furnace blacks are included, confirming the determining influence of the carbon black surface chemistry on the electrical conductivity

Electrically conductive, immobilized bioanodes for microbial fuel cells

International Nuclear Information System (INIS)

Ganguli, R; Dunn, B

2012-01-01

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

Cataract incidence after total-body irradiation

International Nuclear Information System (INIS)

Zierhut, D.; Lohr, F.; Schraube, P.; Huber, P.; Haas, R.; Hunstein, W.; Wannenmacher, M.

1997-01-01

Purpose: Aim of this retrospective study was to evaluate cataract incidence in a homogeneous group of patients after total-body irradiation followed by autologous bone marrow transplantation or peripheral blood stem cell transplantation. Method and Materials: Between 11/1982 and 6/1994 in total 260 patients received in our hospital total-body irradiation for treatment of haematological malignancy. In 1996-96 patients out of these 260 patients were still alive. 85 from these still living patients (52 men, 33 women) answered evaluable on a questionnaire and could be examined ophthalmologically. Median age of these patients was 38,5 years (15 - 59 years) at time of total-body irradiation. Radiotherapy was applied as hyperfractionated total-body irradiation with a median dose of 14,4 Gy in 12 fractions over 4 days. Minimum time between fractions was 4 hours, photons with a energy of 23 MeV were used, and the dose rate was 7 - 18 cGy/min. Results: Median follow-up is now 5,8 years (1,7 - 13 years). Cataract occurred in (28(85)) patients after a median time of 47 months (1 - 104 months). In 6 out of these 28 patients who developed a cataract, surgery of the cataract was performed. Whole-brain irradiation prior to total-body irradiation was more often in the group of patients developing a cataract (14,3%) vs. 10,7% in the group of patients without cataract. Conclusion: Cataract is a common side effect of total-body irradiation. Cataract incidence found in our patients is comparable to results of other centres using a fractionated regimen for total-body irradiation. The hyperfractionated regimen used in our hospital does obviously not result in a even lower cataract incidence. In contrast to acute and late toxicity in other organ/organsystems, hyperfractionation of total-body irradiation does not further reduce toxicity for the eye-lens. Dose rate may have more influence on cataract incidence

Magnetic resonance electrical impedance tomography for measuring electrical conductivity during electroporation

International Nuclear Information System (INIS)

Kranjc, M; Miklavčič, D; Bajd, F; Serša, I

2014-01-01

The electroporation effect on tissue can be assessed by measurement of electrical properties of the tissue undergoing electroporation. The most prominent techniques for measuring electrical properties of electroporated tissues have been voltage–current measurement of applied pulses and electrical impedance tomography (EIT). However, the electrical conductivity of tissue assessed by means of voltage–current measurement was lacking in information on tissue heterogeneity, while EIT requires numerous additional electrodes and produces results with low spatial resolution and high noise. Magnetic resonance EIT (MREIT) is similar to EIT, as it is also used for reconstruction of conductivity images, though voltage and current measurements are not limited to the boundaries in MREIT, hence it yields conductivity images with better spatial resolution. The aim of this study was to investigate and demonstrate the feasibility of the MREIT technique for assessment of conductivity images of tissues undergoing electroporation. Two objects were investigated: agar phantoms and ex vivo liver tissue. As expected, no significant change of electrical conductivity was detected in agar phantoms exposed to pulses of all used amplitudes, while a considerable increase of conductivity was measured in liver tissue exposed to pulses of different amplitudes. (paper)

Electrical conductivity of silicon carbide composites

International Nuclear Information System (INIS)

Scholz, R.; Greeff, J. de; Vinche, C.; Frias Rebelo, A.

1997-01-01

The electrical conductivity was measured on two SiC/SiC composite materials in the temperature range from room temperature up to 1000degC in order to estimate the magnitude of MHD effects in liquid metal blankets if SiC/SiC composites are used as structural materials. For both types of material, the electrical conductivity increased continuously with temperature. The conductivity values ranged from 350 (Ωm) -1 at room temperature to 550 (Ωm) -1 at 1000degC, indicating that the materials tested cannot be treated as an electrical insulator in a MHD analysis for liquid metal blanket studies. (author)

Salinity: Electrical conductivity and total dissolved solids

Science.gov (United States)

The measurement of soil salinity is a quantification of the total salts present in the liquid portion of the soil. Soil salinity is important in agriculture because salinity reduces crop yields by reducing the osmotic potential making it more difficult for the plant to extract water, by causing spe...

Increased electrical conductivity of peptides through annealing process

Directory of Open Access Journals (Sweden)

Seok Daniel Namgung

2017-08-01

Full Text Available Biocompatible biologically occurring polymer is suggested as a component of human implantable devices since conventional inorganic materials are apt to trigger inflammation and toxicity problem within human body. Peptides consisting of aromatic amino acid, tyrosine, are chosen, and enhancement on electrical conductivity is studied. Annealing process gives rise to the decrease on resistivity of the peptide films and the growth of the carrier concentration is a plausible reason for such a decrease on resistivity. The annealed peptides are further applied to an active layer of field effect transistor, in which low on/off current ratio (∼10 is obtained.

Thermophysical Properties of Cold and Vacuum Plasma Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings. Part 1; Electrical and Thermal Conductivity, Thermal Diffusivity, and Total Hemispherical Emissivity

Science.gov (United States)

Raj, S. V.

2017-01-01

This two-part paper reports the thermophysical properties of several cold and vacuum plasma sprayed monolithic Cu and Ni-based alloy coatings. Part I presents the electrical and thermal conductivity, thermal diffusivity, and total hemispherical emissivity data while Part II reports the specific heat capacity data for these coatings. Metallic copper alloys, stoichiometric NiAl and NiCrAlY coatings were fabricated by either the cold sprayed or the vacuum plasma spray deposition processes for thermal property measurements between 77 and 1223 K. The temperature dependencies of the thermal conductivities, thermal diffusivities, electrical conductivities and total hemispherical emissivities of these cold and vacuum sprayed monolithic coatings are reported in this paper. The electrical and thermal conductivity data correlate reasonably well for Cu-8%Cr-1%Al, Cu-23%Cr-5%Al and NiAl in accordance with the Wiedemann-Franz (WF) law although a better fit is obtained using the Smith-Palmer relationship. The Lorentz numbers determined from the WF law are close to the theoretical value.

Method of forming an electrically conductive cellulose composite

Science.gov (United States)

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

2011-11-22

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

Total body irradiation: current indications; L`irradiation corporelle totale: les indications actuelles

Energy Technology Data Exchange (ETDEWEB)

Giraud, P.; Danhier, S.; Dubray, B.; Cosset, J.M. [Institut Curie, 75 - Paris (France)

1998-05-01

The choice of dose and fractionation for total body irradiation is made difficult by the large number of considerations to be taken into account. The outcome of bone marrow transplantation after total body irradiation can be understood in terms of tumor cell killing, engraftment, and normal tissue damage, each of these endpoints being influenced by irradiation-, disease-, transplant-, and patient- related factors. Interpretation of clinical data is further hampered by the overwhelming influence of logistic constraints, the small numbers of randomized studies, and the concomitant variations in total dose and fraction size or dose rate. So far, three cautious conclusions can be drawn in order to tentatively adapt the total body irradiation schedule to clinically-relevant situations. Firstly, the organs at risk for normal tissue damage (lung, liver, lens, kidney) are protected by delivering small doses per fraction at low dose rate. This suggests that, when toxicity is at stake (e.g. in children), fractionated irradiation should be preferred, provided that inter-fraction intervals are long enough. Secondly, fractionated irradiation should be avoided in case of T-cell depleted transplant, given the high risk of graft rejection in this setting. An alternative would be to increase total (or fractional) dose of fractionated total body irradiation, but this approach is likely to induce more normal tissue toxicity. Thirdly, clinical data have shown higher relapse rates in chronic myeloid leukemia after fractionated or low dose rate total body irradiation, suggesting that fractionated irradiation should not be recommended, unless total (or fractional) dose is increased. Total body irradiation-containing regimens, primarily cyclophosphamide / total body irradiation, are either equivalent to or better than the chemotherapy-only regimens, primarily busulfan / cyclophosphamide. Busulfan / cyclophosphamide certainly represents a reasonable alternative, especially in patients who

Electric Conductivity and Dielectric-Breakdown Behavior for Polyurethane Magnetic Elastomers.

Science.gov (United States)

Sasaki, Shuhei; Tsujiei, Yuri; Kawai, Mika; Mitsumata, Tetsu

2017-02-23

The electric-voltage dependence of the electric conductivity for cross-linked and un-cross-linked magnetic elastomers was measured at various magnetic fields, and the effect of cross-linking on the electric conductivity and the dielectric-breakdown behavior was investigated. The electric conductivity for un-cross-linked elastomers at low voltages was independent of magnetic fields and the volume fraction of magnetic particles, indicating the electric conduction in the polyurethane matrix. At high voltages, the electric conductivity increased with the magnetic field, showing the electric conduction via chains of magnetic particles. On the other hand, the electric conductivity at low voltages for cross-linked elastomers with volume fractions below 0.06 was independent of the magnetic field, suggesting the electric conduction in the polyurethane matrix. At volume fractions above 0.14, the electric conductivity increased with the magnetic field, suggesting the electric conduction via chains of magnetic particles. At high voltages, the electric conductivity for cross-linked elastomers with a volume fraction of 0.02 was independent of the magnetic field, indicating the electric conduction through the polyurethane matrix. At volume fractions above 0.06, the electric conductivity suddenly increased at a critical voltage, exhibiting the dielectric breakdown at the bound layer of magnetic particles and/or the discontinuous part between chains.

Mathematical Modeling of Electrical Conductivity of Dielectric with Dispersed Metallic Inclusions

Directory of Open Access Journals (Sweden)

V. S. Zarubin

2015-01-01

elements consists of the dielectric material matrix.Quantitative analysis of two-sided estimates of possible values of the electrical conductivity of the composite, which are constructed by using dual variational electrokinetics problem statement for a heterogeneous solid body, showed that for real dielectric matrix material combinations and metallic inclusions in case when their electrical conductivity can differ by more than 10 orders of magnitude, these estimates can vary widely the specified characteristics of a composite. Therefore, to obtain the estimated effective dependence, a solution to the electrokinetics problem for representative element of the composite structure based on the assumption about ideal conductivity of metallic inclusions is found. It is shown that this dependence reflects properly the influence of the properties of the structural elements of a composite on its electrical conductivity.

3D electrical conductivity tomography of volcanoes

Science.gov (United States)

Soueid Ahmed, A.; Revil, A.; Byrdina, S.; Coperey, A.; Gailler, L.; Grobbe, N.; Viveiros, F.; Silva, C.; Jougnot, D.; Ghorbani, A.; Hogg, C.; Kiyan, D.; Rath, V.; Heap, M. J.; Grandis, H.; Humaida, H.

2018-05-01

Electrical conductivity tomography is a well-established galvanometric method for imaging the subsurface electrical conductivity distribution. We characterize the conductivity distribution of a set of volcanic structures that are different in terms of activity and morphology. For that purpose, we developed a large-scale inversion code named ECT-3D aimed at handling complex topographical effects like those encountered in volcanic areas. In addition, ECT-3D offers the possibility of using as input data the two components of the electrical field recorded at independent stations. Without prior information, a Gauss-Newton method with roughness constraints is used to solve the inverse problem. The roughening operator used to impose constraints is computed on unstructured tetrahedral elements to map complex geometries. We first benchmark ECT-3D on two synthetic tests. A first test using the topography of Mt. St Helens volcano (Washington, USA) demonstrates that we can successfully reconstruct the electrical conductivity field of an edifice marked by a strong topography and strong variations in the resistivity distribution. A second case study is used to demonstrate the versatility of the code in using the two components of the electrical field recorded on independent stations along the ground surface. Then, we apply our code to real data sets recorded at (i) a thermally active area of Yellowstone caldera (Wyoming, USA), (ii) a monogenetic dome on Furnas volcano (the Azores, Portugal), and (iii) the upper portion of the caldera of Kīlauea (Hawai'i, USA). The tomographies reveal some of the major structures of these volcanoes as well as identifying alteration associated with high surface conductivities. We also review the petrophysics underlying the interpretation of the electrical conductivity of fresh and altered volcanic rocks and molten rocks to show that electrical conductivity tomography cannot be used as a stand-alone technique due to the non-uniqueness in

Heat and electrical conductivity of thermotropic liquid crystals

International Nuclear Information System (INIS)

Saidov, N.S.; Majidov, H.; Saburov, B.S.; Safarov, M.M.

1989-01-01

A results of thermal conduction and electrical conduction of chemo tropic liquid crystals are brought in this article. An installation dependence formula of thermal conduction investigating things from the electrical conduction and temperatures is constructed

Electrical conductivity study on polythiophenes films

International Nuclear Information System (INIS)

Youm, I.; Cadene, M.

1994-10-01

The electrical conduction mechanism of two classes of polythiophenes: polythiophene (PT) and poly(3-methylthiophene) (PMT) films containing various levels of doping counter-ions was investigated. The temperature dependence of electrical conductivity obeys the Mott equation based on variable range hopping. The dimension of the variable range hopping is correlated with the structure of the conducting polymer. It seems for these polymers that carrier transport via mobile conjugational defects does not play a detectable role. (author). 17 refs, 3 figs, 1 tab

Electrical conductivity modeling in fractal non-saturated porous media

Science.gov (United States)

Wei, W.; Cai, J.; Hu, X.; Han, Q.

2016-12-01

The variety of electrical conductivity in non-saturated conditions is important to study electric conduction in natural sedimentary rocks. The electrical conductivity in completely saturated porous media is a porosity-function representing the complex connected behavior of single conducting phases (pore fluid). For partially saturated conditions, the electrical conductivity becomes even more complicated since the connectedness of pore. Archie's second law is an empirical electrical conductivity-porosity and -saturation model that has been used to predict the formation factor of non-saturated porous rock. However, the physical interpretation of its parameters, e.g., the cementation exponent m and the saturation exponent n, remains questionable. On basis of our previous work, we combine the pore-solid fractal (PSF) model to build an electrical conductivity model in non-saturated porous media. Our theoretical porosity- and saturation-dependent models contain endmember properties, such as fluid electrical conductivities, pore fractal dimension and tortuosity fractal dimension (representing the complex degree of electrical flowing path). We find the presented model with non-saturation-dependent electrical conductivity datasets indicate excellent match between theory and experiments. This means the value of pore fractal dimension and tortuosity fractal dimension change from medium to medium and depends not only on geometrical properties of pore structure but also characteristics of electrical current flowing in the non-saturated porous media.

Electrically conductive carbon nanofiber/paraffin wax composites for electric thermal storage

International Nuclear Information System (INIS)

Zhang Kun; Han Baoguo; Yu Xun

2012-01-01

Highlights: ► Carbon nanofiber (CNF)/paraffin wax composite is found to be a promising electric thermal storage material. ► The thermal storage capacity of CNF/paraffin wax composite is five times of traditional electric thermal storage material. ► CNF is shown to be an effective conductive filler for the composite. - Abstract: The research of electric thermal storage (ETS) has attracted a lot of attention recently, which converts off-peak electrical energy into thermal energy and release it later at peak hours. In this study, new electric thermal storage composites are developed by employing paraffin wax as thermal storage media and carbon nanofiber (CNF) as conductive fillers. Electric heating and thermal energy release performances of the CNF/paraffin wax composites are experimentally investigated. Experimental results show that, when the composites are heated to about 70 °C, the developed electrically conductive CNF/paraffin wax composites present a thermal storage capacity of about 280 kJ/kg, which is five times of that of traditional thermal storage medium such as ceramic bricks (54 kJ/kg). The CNF/paraffin wax composites can also effectively store the thermal energy and release the thermal energy in later hours.

Thermal and electrical conductivities of Cd-Zn alloys

International Nuclear Information System (INIS)

Saatci, B; Ari, M; Guenduez, M; Meydaneri, F; Bozoklu, M; Durmus, S

2006-01-01

The composition and temperature dependences of the thermal and electrical conductivities of three different Cd-Zn alloys have been investigated in the temperature range of 300-650 K. Thermal conductivities of the Cd-Zn alloys have been determined by using the radial heat flow method. It has been found that the thermal conductivity decreases slightly with increasing temperature and the data of thermal conductivity are shifting together to the higher values with increasing Cd composition. In addition, the electrical measurements were determined by using a standard DC four-point probe technique. The resistivity increases linearly and the electrical conductivity decreases exponentially with increasing temperature. The resistivity and electrical conductivity are independent of composition of Cd and Zn. Also, the temperature coefficient of Cd-Zn alloys has been determined, which is independent of composition of Cd and Zn. Finally, Lorenz number has been calculated using the thermal and electrical conductivity values at 373 and 533 K. The results satisfy the Wiedemann-Franz (WF) relation at T 373 K), the WF relation could not hold and the phonon component contribution of thermal conductivity dominates the thermal conduction

Total qualification of class 1E electric equipment

International Nuclear Information System (INIS)

Chauvin, G.

1982-09-01

For nuclear power plant projects in France, Framatome and its partners Electricite de France (EDF) and the Commissariat a l'Energie Atomique (CEA) have responded to the present qualification context by implementing a wide-ranging qualification program to acquire significant organizational and practical experience. The following sections detail Framatome's approach to the activities of an organization mandated to provide a complete spectrum of qualification services. Thorough implementation of a Class 1E electric equipment qualification program by the competent organization or qualifier entails completion of three consecutive steps: 1) program preparation, 2) program implementation, and 3) analysis of test results and conclusion. The qualifier assumes extensive responsibility for each of these steps. The following sections present test facilities used in France to conduct a total qualification program for Class 1E electric equipment

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

KAUST Repository

Zhou, Jian

2013-07-10

We describe a strategy to design highly electrically conductive polycarbonate nanocomposites by using multiwalled carbon nanotubes (MWCNTs) coated with a thin layer of poly(3,4-ethylenedioxythiophene)/ poly(styrenesulfonate), a conductive polymer. We found that this coating method improves the electrical properties of the nanocomposites in two ways. First, the coating becomes the main electrical conductive path. Second, the coating promotes the formation of a percolation network at a low filler concentration (0.3 wt %). To tailor the electrical properties of the conductive polymer coating, we used a polar solvent ethylene glycol, and we can tune the final properties of the nanocomposite by controlling the concentrations of the elementary constituents or the intrinsic properties of the conductive polymer coating. This very flexible technique allows for tailoring the properties of the final product. © 2013 American Chemical Society.

Electrical and thermal conductivities in dense plasmas

Energy Technology Data Exchange (ETDEWEB)

Faussurier, G., E-mail: gerald.faussurier@cea.fr; Blancard, C.; Combis, P.; Videau, L. [CEA, DAM, DIF, F-91297 Arpajon (France)

2014-09-15

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

Stay connected: Electrical conductivity of microbial aggregates.

Science.gov (United States)

Li, Cheng; Lesnik, Keaton Larson; Liu, Hong

2017-11-01

The discovery of direct extracellular electron transfer offers an alternative to the traditional understanding of diffusional electron exchange via small molecules. The establishment of electronic connections between electron donors and acceptors in microbial communities is critical to electron transfer via electrical currents. These connections are facilitated through conductivity associated with various microbial aggregates. However, examination of conductivity in microbial samples is still in its relative infancy and conceptual models in terms of conductive mechanisms are still being developed and debated. The present review summarizes the fundamental understanding of electrical conductivity in microbial aggregates (e.g. biofilms, granules, consortia, and multicellular filaments) highlighting recent findings and key discoveries. A greater understanding of electrical conductivity in microbial aggregates could facilitate the survey for additional microbial communities that rely on direct extracellular electron transfer for survival, inform rational design towards the aggregates-based production of bioenergy/bioproducts, and inspire the construction of new synthetic conductive polymers. Copyright © 2017 Elsevier Inc. All rights reserved.

Rapidly curable electrically conductive clear coatings

Energy Technology Data Exchange (ETDEWEB)

Bowman, Mark P.; Anderson, Lawrence G.; Post, Gordon L.

2018-01-16

Rapidly curable electrically conductive clear coatings are applied to substrates. The electrically conductive clear coating includes to clear layer having a resinous binder with ultrafine non-stoichiometric tungsten oxide particles dispersed therein. The clear coating may be rapidly cured by subjecting the coating to infrared radiation that heats the tungsten oxide particles and surrounding resinous binder. Localized heating increases the temperature of the coating to thereby thermally cure the coating, while avoiding unwanted heating of the underlying substrate.

Double anisotropic electrically conductive flexible Janus-typed membranes.

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Li, Xiaobing; Ma, Qianli; Tian, Jiao; Xi, Xue; Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Xinlu; Wang, Jinxian; Liu, Guixia

2017-12-07

Novel type III anisotropic conductive films (ACFs), namely flexible Janus-typed membranes, were proposed, designed and fabricated for the first time. Flexible Janus-typed membranes composed of ordered Janus nanobelts were constructed by electrospinning, which simultaneously possess fluorescence and double electrically conductive anisotropy. For the fabrication of the Janus-typed membrane, Janus nanobelts comprising a conductive side and an insulative-fluorescent side were primarily fabricated, and then the Janus nanobelts are arranged into parallel arrays using an aluminum rotary drum as the collector to obtain a single anisotropically conductive film. Subsequently, a secondary electrospinning process was applied to the as-prepared single anisotropically conductive films to acquire the final Janus-typed membrane. For this Janus-typed membrane, namely its left-to-right structure, anisotropic electrical conduction synchronously exists on both sides, and furthermore, the two electrically conductive directions are perpendicular. By modulating the amount of Eu(BA) 3 phen complex and conducting polyaniline (PANI), the characteristics and intensity of the fluorescence-electricity dual-function in the membrane can be tuned. The high integration of this peculiar Janus-typed membrane with simultaneous double electrically conductive anisotropy-fluorescent dual-functionality is successfully realized in this study. This design philosophy and preparative technique will provide support for the design and construction of new types of special nanostructures with multi-functionality.

Global Electric Circuit Implications of Total Current Measurements over Electrified Clouds

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Mach, Douglas M.; Blakeslee, Richard J.; Bateman, Monte G.

2009-01-01

We determined total conduction (Wilson) currents and flash rates for 850 overflights of electrified clouds spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, with and without lightning, and with positive and negative Wilson currents. We combined these individual storm overflight statistics with global diurnal lightning variation data from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) to estimate the thunderstorm and electrified shower cloud contributions to the diurnal variation in the global electric circuit. The contributions to the global electric circuit from lightning producing clouds are estimated by taking the mean current per flash derived from the overflight data for land and ocean overflights and combining it with the global lightning rates (for land and ocean) and their diurnal variation derived from the LIS/OTD data. We estimate the contribution of non-lightning producing electrified clouds by assuming several different diurnal variations and total non-electrified storm counts to produce estimates of the total storm currents (lightning and non-lightning producing storms). The storm counts and diurnal variations are constrained so that the resultant total current diurnal variation equals the diurnal variation in the fair weather electric field (+/-15%). These assumptions, combined with the airborne and satellite data, suggest that the total mean current in the global electric circuit ranges from 2.0 to 2.7 kA, which is greater than estimates made by others using other methods.

Electric Field Measurement of the Living Human Body for Biomedical Applications: Phase Measurement of the Electric Field Intensity

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Ichiro Hieda

2013-01-01

Full Text Available The authors are developing a technique for conducting measurements inside the human body by applying a weak electric field at a radio frequency (RF. Low RF power is fed to a small antenna, and a similar antenna located 15–50 cm away measures the electric field intensity. Although the resolution of the method is low, it is simple, safe, cost-effective, and able to be used for biomedical applications. One of the technical issues suggested by the authors' previous studies was that the signal pattern acquired from measurement of a human body was essentially different from that acquired from a phantom. To trace the causes of this difference, the accuracy of the phase measurements was improved. This paper describes the new experimental system that can measure the signal phase and amplitude and reports the results of experiments measuring a human body and a phantom. The results were analyzed and then discussed in terms of their contribution to the phase measurement.

High electric field conduction in low-alkali boroaluminosilicate glass

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Dash, Priyanka; Yuan, Mengxue; Gao, Jun; Furman, Eugene; Lanagan, Michael T.

2018-02-01

Electrical conduction in silica-based glasses under a low electric field is dominated by high mobility ions such as sodium, and there is a transition from ionic transport to electronic transport as the electric field exceeds 108 V/m at low temperatures. Electrical conduction under a high electric field was investigated in thin low-alkali boroaluminosilicate glass samples, showing nonlinear conduction with the current density scaling approximately with E1/2, where E is the electric field. In addition, thermally stimulated depolarization current (TSDC) characterization was carried out on room-temperature electrically poled glass samples, and an anomalous discharging current flowing in the same direction as the charging current was observed. High electric field conduction and TSDC results led to the conclusion that Poole-Frenkel based electronic transport occurs in the mobile-cation-depleted region adjacent to the anode, and accounts for the observed anomalous current.

Pressure and graphite effects on electrical conductivity in pyroxene

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Wang, D.; Liu, T.; Shen, K.; Li, B.

2017-12-01

The geophysical observations including magnetotelluric (MT) and geomagnetic deep sounding show the distribution of electrical conductivity in the Earth's interior. The laboratory-based conductivity measurements of minerals and rocks are usually used to interpret the geophysical observations. Pyroxene is the second most abundant components in the upper mantle, and the electrical conductivity of pyroxene is important to understanding the bulk electrical conductivity. The electrical conductivity of a mineral is affected by many factors, such as its chemical composition, temperature, pressure. Here we report the effects of pressure and graphite on the electrical conductivity of pyroxene and applied to interpretation of MT observation. The starting materials are natural of orthopyroxene and clinopyroxe crystals. A powder sample with grain size 10 um was packed in a Mo capsule and hot-pressed at high pressures and temperatures using a 1000-ton Walker-type uniaxial split-cylinder apparatus. A mixture of pyroxene and a few percent of diamond was annealed at high pressure and temperature. All the hot-pressed samples before and after electrical conductivity measurements, were characterized by scanning electron microscopy, Fourier-Transform Infrared and Raman spectroscopy. High pressure conductivity experiments were carried out in a Walker-type multi-anvil apparatus using a 14/8 assembly. We use a Solartron 1260 Impedance/Gain -phase analyzer with 1V applied voltage within a frequency range of 1M-0.1 Hz to collect data. Complex impedance data on were collected in several heating and cooling cycles The electrical conductivity of pyroxene was made at 4,7,10 GPa, and electrical conductivity of the graphite-bearing pyroxene was measured at 4GPa. The results show the electrical conductivity decrease with the increasing of pressure, which may correspond to the transform from orthopyroxene to clinopyroxene. The results can be used to explain a drop of the electrical conductivity in

Enhanced electrical conductivity in graphene and boron nitride nanoribbons in large electric fields

Science.gov (United States)

Chegel, Raad

2018-02-01

Based on data of density function theory (DFT) as the input of tight binding model, the electrical conductivity (σ(T)) of graphene nanoribbos (GNRs) and Boron Nitride nanoribbos (BNNRs) under external electric fields with different wide are studied using the Green's function method. The BNNRs are wide band gap semiconductor and they are turned into metal depending on their electric field strength. The σ(T) shows increasing in low temperature region and after reaching the maximum value, it will decrease in high temperature region. In lower temperature ranges, the electrical conductivity of the GNRs is greater than that of the BNNRs. In a low temperature region, the σ(T) of GNRs increases linearly with temperature unlike the BNNRs. The electrical conductivity are strongly dependent on the electric field strength.

Processing and electrical conductivity of lanthanum gallate core-shell heterostructures

Directory of Open Access Journals (Sweden)

Gomes, Eduarda

2006-06-01

Full Text Available The electrical properties of a lanthanum gallate solid electrolyte were modified by selectively doping the grain boundaries with Fe. This was achieved by sandwiching a La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM dense pellet between LaFeO3 samples. Annealing at 1550°C in air for several hours promoted Fe diffusion into LSGM via the grain boundaries. Scanning electron microscopy and energy-dispersive spectroscopy analyses showed that iron was located at the grain boundary while the grain bulk preserved the LSGM composition. Impedance spectra obtained at low temperature consist of the two usual bulk and grain boundary contributions. A significant increase in total conductivity was observed for the iron-doped samples, the effect being greater for the grain boundary contribution. The total conductivity measured for the iron-containing material revealed a slight decrease with decreasing oxygen partial pressure, suggesting the onset of p-type electronic conduction. Estimates of the p-type electronic conductivity (σp were obtained by fitting the low temperature impedance spectra to a simple equivalent circuit including one parallel electronic branch. The value for σp in air at 300°C is 3.1×10-6 S/cm and the activation energy is 75.1 kJ/mol between 300 and 400°C.

Las propiedades elécticas de un electrolito sólido de galato de lantano se han modificado mediante un dopado eléctrico de Fe en borde de grano. Esto se consiguió preparando una estructura de sandwich con una plantilla densa de La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM entre las muestras de LaFeO3. Un tratamiento de varias horas a 1550ºC en aire favoreció la difusión de Fe a lo largo de los bordes de grano. Los análisis mediante microscopia electrónica de barrido y espectroscopía de energía dispersada muestran que el hierro se localiza en borde de grano mientras que se preserva la composición de LSGM en el interior de grano. En las muestras dopadas con hierro se observa un aumento de

Chapter A6. Section 6.3. Specific Electrical Conductance

Science.gov (United States)

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

2005-01-01

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

Noninvasive electrical conductivity measurement by MRI: a test of its validity and the electrical conductivity characteristics of glioma.

Science.gov (United States)

Tha, Khin Khin; Katscher, Ulrich; Yamaguchi, Shigeru; Stehning, Christian; Terasaka, Shunsuke; Fujima, Noriyuki; Kudo, Kohsuke; Kazumata, Ken; Yamamoto, Toru; Van Cauteren, Marc; Shirato, Hiroki

2018-01-01

This study noninvasively examined the electrical conductivity (σ) characteristics of diffuse gliomas using MRI and tested its validity. MRI including a 3D steady-state free precession (3D SSFP) sequence was performed on 30 glioma patients. The σ maps were reconstructed from the phase images of the 3D SSFP sequence. The σ histogram metrics were extracted and compared among the contrast-enhanced (CET) and noncontrast-enhanced tumour components (NCET) and normal brain parenchyma (NP). Difference in tumour σ histogram metrics among tumour grades and correlation of σ metrics with tumour grades were tested. Validity of σ measurement using this technique was tested by correlating the mean tumour σ values measured using MRI with those measured ex vivo using a dielectric probe. Several σ histogram metrics of CET and NCET of diffuse gliomas were significantly higher than NP (Bonferroni-corrected p ≤ .045). The maximum σ of NCET showed a moderate positive correlation with tumour grade (r = .571, Bonferroni-corrected p = .018). The mean tumour σ measured using MRI showed a moderate positive correlation with the σ measured ex vivo (r = .518, p = .040). Tissue σ can be evaluated using MRI, incorporation of which may better characterise diffuse gliomas. • This study tested the validity of noninvasive electrical conductivity measurements by MRI. • This study also evaluated the electrical conductivity characteristics of diffuse glioma. • Gliomas have higher electrical conductivity values than the normal brain parenchyma. • Noninvasive electrical conductivity measurement can be helpful for better characterisation of glioma.

Managing total corporate electricity/energy market risks

International Nuclear Information System (INIS)

Henney, A.; Keers, G.

1998-01-01

The banking industry has developed a tool kit of very useful value at risk techniques for hedging risk, but these techniques must be adapted to the special complexities of the electricity market. This paper starts with a short history of the use of value-at-risk (VAR) techniques in banking risk management and then examines the specific and, in many instances, complex risk management challenges faced by electric companies from the behavior of prices in electricity markets and from the character of generation and electric retailing risks. The third section describes the main methods for making VAR calculations along with an analysis of their suitability for analyzing the risks of electricity portfolios and the case for using profit at risk and downside risk as measures of risk. The final section draws the threads together and explains how to look at managing total corporate electricity market risk, which is a big step toward managing total corporate energy market risk

New equivalent-electrical circuit model and a practical measurement method for human body impedance.

Science.gov (United States)

Chinen, Koyu; Kinjo, Ichiko; Zamami, Aki; Irei, Kotoyo; Nagayama, Kanako

2015-01-01

Human body impedance analysis is an effective tool to extract electrical information from tissues in the human body. This paper presents a new measurement method of impedance using armpit electrode and a new equivalent circuit model for the human body. The lowest impedance was measured by using an LCR meter and six electrodes including armpit electrodes. The electrical equivalent circuit model for the cell consists of resistance R and capacitance C. The R represents electrical resistance of the liquid of the inside and outside of the cell, and the C represents high frequency conductance of the cell membrane. We propose an equivalent circuit model which consists of five parallel high frequency-passing CR circuits. The proposed equivalent circuit represents alpha distribution in the impedance measured at a lower frequency range due to ion current of the outside of the cell, and beta distribution at a high frequency range due to the cell membrane and the liquid inside cell. The calculated values by using the proposed equivalent circuit model were consistent with the measured values for the human body impedance.

Electric conductivity of TlInTe2 monocrystal in strong electric fields

International Nuclear Information System (INIS)

Zarbaliev, M.M.; Godzhaev, Eh.M.; Gadzhiev, V.A.

1980-01-01

Electric condUctivity of the TlInTe 2 single crystal in strong electric fields has been studied in the range of 77-300 K. The electron part of the TlInTe 2 dielectric constant has been found to be 4. The dependence of the activation energy of current carriers on the electric field strength is constructed and the value of the activation energy of current carriers in the absence of an electric field is determined by the extrapolation method. The results of the experiments are in good agreement with the Frenkel-Pool theory, and this affords grounds for asserting that the obtained dependences of electric conductivity on temperature and the electric field strength are defined by variation in the current carrier concentration due to action of the thermal-electron ionization mechanism

Electrical conductivity and ion diffusion in porcine meniscus: effects of strain, anisotropy, and tissue region.

Science.gov (United States)

Kleinhans, Kelsey L; McMahan, Jeffrey B; Jackson, Alicia R

2016-09-06

The purpose of the present study was to investigate the effects of mechanical strain, anisotropy, and tissue region on electrical conductivity and ion diffusivity in meniscus fibrocartilage. A one-dimensional, 4-wire conductivity experiment was employed to measure the electrical conductivity in porcine meniscus tissues from two tissue regions (horn and central), for two tissue orientations (axial and circumferential), and for three levels of compressive strain (0%, 10%, and 20%). Conductivity values were then used to estimate the relative ion diffusivity in meniscus. The water volume fraction of tissue specimens was determined using a buoyancy method. A total of 135 meniscus samples were measured; electrical conductivity values ranged from 2.47mS/cm to 4.84mS/cm, while relative ion diffusivity was in the range of 0.235 to 0.409. Results show that electrical conductivity and ion diffusion are significantly anisotropic (pmeniscus fibrocartilage, which is essential in developing new strategies to treat and/or prevent tissue degeneration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrical conduction of a XLPE nanocomposite

Science.gov (United States)

Park, Yong-Jun; Sim, Jae-Yong; Lim, Kee-Joe; Nam, Jin-Ho; Park, Wan-Gi

2014-07-01

The resistivity, breakdown strength, and formation of space charges are very important factors for insulation design of HVDC cable. It is known that a nano-sized metal-oxide inorganic filler reduces the formation of space charges in the polymer nanocomposite. Electrical conduction of cross-linked polyethylene(XLPE) nanocomposite insulating material is investigated in this paper. The conduction currents of two kinds of XLPE nanocomposites and XLPE without nano-filler were measured at temperature of 303 ~ 363 K under the applied electric fields of 10 ~ 50 kV/mm. The current of the nanocomposite specimen is smaller than that of XLPE specimen without nano-filler. The conduction mechanism may be explained in terms of Schottky emission and multi-core model.

Wireless communication with implanted medical devices using the conductive properties of the body.

Science.gov (United States)

Ferguson, John E; Redish, A David

2011-07-01

Many medical devices that are implanted in the body use wires or wireless radiofrequency telemetry to communicate with circuitry outside the body. However, the wires are a common source of surgical complications, including breakage, infection and electrical noise. In addition, radiofrequency telemetry requires large amounts of power and results in low-efficiency transmission through biological tissue. As an alternative, the conductive properties of the body can be used to enable wireless communication with implanted devices. In this article, several methods of intrabody communication are described and compared. In addition to reducing the complications that occur with current implantable medical devices, intrabody communication can enable novel types of miniature devices for research and clinical applications.

Effective electrical and thermal conductivity of multifilament twisted superconductors

International Nuclear Information System (INIS)

Chechetkin, V.R.

2013-01-01

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

Electrical actuation of electrically conducting and insulating droplets using ac and dc voltages

International Nuclear Information System (INIS)

Kumari, N; Bahadur, V; Garimella, S V

2008-01-01

Electrical actuation of liquid droplets at the microscale offers promising applications in the fields of microfluidics and lab-on-chip devices. Much prior research has targeted the electrical actuation of electrically conducting liquid droplets using dc voltages (classical electrowetting). Electrical actuation of conducting droplets using ac voltages and the actuation of insulating droplets (using dc or ac voltages) has remained relatively unexplored. This paper utilizes an energy-minimization-based analytical framework to study the electrical actuation of a liquid droplet (electrically conducting or insulating) under ac actuation. It is shown that the electromechanical regimes of classical electrowetting, electrowetting under ac actuation and insulating droplet actuation can be extracted from the generic electromechanical actuation framework, depending on the electrical properties of the droplet, the underlying dielectric layer and the frequency of the actuation voltage. This paper also presents experiments which quantify the influence of the ac frequency and the electrical properties of the droplet on its velocity under electrical actuation. The velocities of droplets moving between two parallel plates under ac actuation are experimentally measured; these velocities are then related to the actuation force on the droplet which is predicted by the electromechanical model developed in this work. It is seen that the droplet velocities are strongly dependent on the frequency of the ac actuation voltage; the cut-off ac frequency, above which the droplet fails to actuate, is experimentally determined and related to the electrical conductivity of the liquid. This paper then analyzes and directly compares the various electromechanical regimes for the actuation of droplets in microfluidic applications

Electrically conductive polymer concrete coatings

Science.gov (United States)

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

1990-01-01

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

Studies on electrical conductivity of poly phenylene vinylene

International Nuclear Information System (INIS)

Khattab, Asaad F.; Ahmad, Saddam M.

2009-01-01

Four Pp polymers have been synthesized through Wit ting reaction, 1 poly(p-phenylene vinylene), 2 = poly(p phenylene vinylene-co-m-phenylene vinylene), 3 = poly(p-phenylene vinylene-co-o-phenylene vinylene) and 4 poly(p-phenylene-1,5-hexadiene). Electrical conductivity measurements show that the conductivity of polymer 3 is higher than that of polymers 1 and 2. The dihedral angle measurements indicates that the irregularity of polymer chains is the main reason for this fact. The interruption of chain conjugation by aliphatic segments (polymer 4) will increase the conductivity by increasing the chain mobility.The electrical conductivity of the polymers is increased by doping with iodine and by raising the temperature. The effect of annealing with different temperatures on conductivity was studied; the results show that structural conformation of polymeric chain is the main factor affecting electrical conductivity. (author)

Electrical conductivity of free-standing mesoporous silicon thin films

International Nuclear Information System (INIS)

Khardani, M.; Bouaicha, M.; Dimassi, W.; Zribi, M.; Aouida, S.; Bessais, B.

2006-01-01

The effective electrical conductivity of free-standing p + -type porous silicon layers having porosities ranging from 30% to 80% was studied at both experimental and theoretical sides. An Effective Medium Approximation (EMA) model was used as a theoretical support. The porous silicon (PS) films were prepared by the electrochemical etching method for different values of the anodic current density. In order to model the PS electrical conductivity, the free-standing porous layer was assumed to be formed of three phases; vacuum, oxide and Si nanocrystallites. The analytical expression of the electrical conductivity of the Si nanocrystallites was established using the quantum confinement theory. This enables us to correlate the electrical conductivity of the mesoporous film to the value of the effective band gap energy estimated from the absorption coefficient. A perfect agreement between the theoretical and the experimental electrical conductivity values was obtained for all prospected PS porosities

A method for total body irradiation

International Nuclear Information System (INIS)

Yasukochi, Hiroshi; Higashi, Shizuka; Okuhata, Yoshitaka; Lee, Keiichi; Ishioka, Kuniaki; Murakami, Koji; Nagai, Jun; Kuniyasu, Yoshio

1988-01-01

In these two years, we have treated four infant patients of acute leukemia by Cobalt-60 total body irradiation and bone marrow transplantation. During total body irradiation, thermoluminescence dosimeters were attached to the skin of patients. For four patients, nine dosimetries were performed. Reliability of this method was examined by phantom experiment. Every irradiation for the patient per fraction was 2.4 Gy, that is, 60 cGy for each four positions, right decubitus A-P and PA directions and left decubitus A-P and PA directions under aseptic circumstances. Radiation dose was uniform by this technique for each patient, and average determined dose for surface of the patients was between 87 % and 106 % compared with the air dose of the center of aseptic space (wagon). As the result, we suggest that this method is suitable for the total body irradiation of acute leukemia of infant. (author)

Wet method for measuring starch gelatinization temperature using electrical conductivity.

Science.gov (United States)

Morales-Sanchez, E; Figueroa, J D C; Gaytan-Martínez, M

2009-09-01

The objective of the present study was to develop a method for obtaining the gelatinization temperature of starches by using electrical conductivity. Native starches from corn, rice, potato, and wheat were prepared with different proportions of water and heated from room temperature to 90 degrees C, in a device especially designed for monitoring the electrical conductivity as a function of temperature. The results showed a linear trend of the electrical conductivity with the temperature until it reaches the onset gelatinization temperature. After that point, the electrical conductivity presented an increment or decrement depending on the water content in the sample and it was related to starch swelling and gelatinization phenomena. At the end gelatinization temperature, the conductivity becomes stable and linear, indicating that there are no more changes of phase. The starch gelatinization parameter, which was evaluated in the 4 types of starches using the electrical conductivity, was compared with those obtained by using differential scanning calorimeter (DSC). The onset temperature at which the electrical conductivity increased or decreased was found to be similar to that obtained by DSC. Also, the final temperature at which the electrical conductivity returned to linearity matched the end gelatinization temperature of the DSC. Further, a wet method for measuring the onset, peak, and end gelatinization temperatures as a function of temperature using the electrical conductivity curves is presented for a starch-water suspension.

Microstructure, electrical conductivity and modulus spectra of CdI{sub 2} doped nanocomposite-electrolytes

Energy Technology Data Exchange (ETDEWEB)

Kundu, Ranadip [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India); Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Roy, Debasish [Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Bhattacharya, Sanjib, E-mail: sanjib_ssp@yahoo.co.in [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India)

2017-02-15

Ionic conductivity and dielectric behavior of Ag{sub 2}O–CdI{sub 2}–CdO nanocomposite system have been studied. X-ray diffraction has been carried out to obtain the crystallite sizes and the growth of CdO dispersed in glass-matrices. Total conductivity of them shows thermally activated nature. It is observed that total conductivity decreases and corresponding activation energy for conduction follows opposite behavior. The high-frequency ac conductivity may correspond to a nonrandom, correlated and sub-diffusive motion of Ag{sup +} ions. Conductivity relaxation time is found to increase. The nature of scaling of the conductivity as well as modulus spectra indicates that the electrical relaxation of Ag{sup +} is temperature independent but depends upon composition.

Computational analysis of electrical conduction in hybrid nanomaterials with embedded non-penetrating conductive particles

Science.gov (United States)

Cai, Jizhe; Naraghi, Mohammad

2016-08-01

In this work, a comprehensive multi-resolution two-dimensional (2D) resistor network model is proposed to analyze the electrical conductivity of hybrid nanomaterials made of insulating matrix with conductive particles such as CNT reinforced nanocomposites and thick film resistors. Unlike existing approaches, our model takes into account the impenetrability of the particles and their random placement within the matrix. Moreover, our model presents a detailed description of intra-particle conductivity via finite element analysis, which to the authors’ best knowledge has not been addressed before. The inter-particle conductivity is assumed to be primarily due to electron tunneling. The model is then used to predict the electrical conductivity of electrospun carbon nanofibers as a function of microstructural parameters such as turbostratic domain alignment and aspect ratio. To simulate the microstructure of single CNF, randomly positioned nucleation sites were seeded and grown as turbostratic particles with anisotropic growth rates. Particle growth was in steps and growth of each particle in each direction was stopped upon contact with other particles. The study points to the significant contribution of both intra-particle and inter-particle conductivity to the overall conductivity of hybrid composites. Influence of particle alignment and anisotropic growth rate ratio on electrical conductivity is also discussed. The results show that partial alignment in contrast to complete alignment can result in maximum electrical conductivity of whole CNF. High degrees of alignment can adversely affect conductivity by lowering the probability of the formation of a conductive path. The results demonstrate approaches to enhance electrical conductivity of hybrid materials through controlling their microstructure which is applicable not only to carbon nanofibers, but also many other types of hybrid composites such as thick film resistors.

Feasibility study of helical tomotherapy for total body or total marrow irradiation

International Nuclear Information System (INIS)

Hui, Susanta K.; Kapatoes, Jeff; Fowler, Jack; Henderson, Douglas; Olivera, Gustavo; Manon, Rafael R.; Gerbi, Bruce; Mackie, T. R.; Welsh, James S.

2005-01-01

Total body radiation (TBI) has been used for many years as a preconditioning agent before bone marrow transplantation. Many side effects still plague its use. We investigated the planning and delivery of total body irradiation (TBI) and selective total marrow irradiation (TMI) and a reduced radiation dose to sensitive structures using image-guided helical tomotherapy. To assess the feasibility of using helical tomotherapy (A) we studied variations in pitch, field width, and modulation factor on total body and total marrow helical tomotherapy treatments. We varied these parameters to provide a uniform dose along with a treatment times similar to conventional TBI (15-30 min). (B) We also investigated limited (head, chest, and pelvis) megavoltage CT (MVCT) scanning for the dimensional pretreatment setup verification rather than total body MVCT scanning to shorten the overall treatment time per treatment fraction. (C) We placed thermoluminescent detectors (TLDs) inside a Rando phantom to measure the dose at seven anatomical sites, including the lungs. A simulated TBI treatment showed homogeneous dose coverage (±10%) to the whole body. Doses to the sensitive organs were reduced by 35%-70% of the target dose. TLD measurements on Rando showed an accurate dose delivery (±7%) to the target and critical organs. In the TMI study, the dose was delivered conformally to the bone marrow only. The TBI and TMI treatment delivery time was reduced (by 50%) by increasing the field width from 2.5 to 5.0 cm in the inferior-superior direction. A limited MVCT reduced the target localization time 60% compared to whole body MVCT. MVCT image-guided helical tomotherapy offers a novel method to deliver a precise, homogeneous radiation dose to the whole body target while reducing the dose significantly to all critical organs. A judicious selection of pitch, modulation factor, and field size is required to produce a homogeneous dose distribution along with an acceptable treatment time. In

On the flow of an electrically conducting gas past a slender body of revolution placed in a circular wind tunnel in the presence of a crossed magnetic field

International Nuclear Information System (INIS)

Suwa, Shigeaki; Kusukawa, Ken-ichi.

1976-01-01

The wind tunnel interference problem in magnetohydrodynamics, in which an inviscid compressible fluid with small electrical conductivity flows steadily past a slender axi-symmetric pointed body of revolution placed in a cylindrical perfectly insulated wind tunnel, in the presence of a crossed magnetic field, is considered. Using the analytical method which was studied by one of the present authors, the streamlines and the space charge in a cross section are calculated. (auth.)

Mussel-Inspired Anisotropic Nanocellulose and Silver Nanoparticle Composite with Improved Mechanical Properties, Electrical Conductivity and Antibacterial Activity

Directory of Open Access Journals (Sweden)

Hoang-Linh Nguyen

2016-03-01

Full Text Available Materials for wearable devices, tissue engineering and bio-sensing applications require both antibacterial activity to prevent bacterial infection and biofilm formation, and electrical conductivity to electric signals inside and outside of the human body. Recently, cellulose nanofibers have been utilized for various applications but cellulose itself has neither antibacterial activity nor conductivity. Here, an antibacterial and electrically conductive composite was formed by generating catechol mediated silver nanoparticles (AgNPs on the surface of cellulose nanofibers. The chemically immobilized catechol moiety on the nanofibrous cellulose network reduced Ag+ to form AgNPs on the cellulose nanofiber. The AgNPs cellulose composite showed excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria. In addition, the catechol conjugation and the addition of AgNP induced anisotropic self-alignment of the cellulose nanofibers which enhances electrical and mechanical properties of the composite. Therefore, the composite containing AgNPs and anisotropic aligned the cellulose nanofiber may be useful for biomedical applications.

Electrical and Thermal Conductivity and Conduction Mechanism of Ge2Sb2Te5 Alloy

Science.gov (United States)

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

2018-06-01

Ge2Sb2Te5 alloy has drawn much attention due to its application in phase-change random-access memory and potential as a thermoelectric material. Electrical and thermal conductivity are important material properties in both applications. The aim of this work is to investigate the temperature dependence of the electrical and thermal conductivity of Ge2Sb2Te5 alloy and discuss the thermal conduction mechanism. The electrical resistivity and thermal conductivity of Ge2Sb2Te5 alloy were measured from room temperature to 823 K by four-terminal and hot-strip method, respectively. With increasing temperature, the electrical resistivity increased while the thermal conductivity first decreased up to about 600 K then increased. The electronic component of the thermal conductivity was calculated from the Wiedemann-Franz law using the resistivity results. At room temperature, Ge2Sb2Te5 alloy has large electronic thermal conductivity and low lattice thermal conductivity. Bipolar diffusion contributes more to the thermal conductivity with increasing temperature. The special crystallographic structure of Ge2Sb2Te5 alloy accounts for the thermal conduction mechanism.

Electrical and Thermal Conductivity and Conduction Mechanism of Ge2Sb2Te5 Alloy

Science.gov (United States)

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

2017-11-01

Ge2Sb2Te5 alloy has drawn much attention due to its application in phase-change random-access memory and potential as a thermoelectric material. Electrical and thermal conductivity are important material properties in both applications. The aim of this work is to investigate the temperature dependence of the electrical and thermal conductivity of Ge2Sb2Te5 alloy and discuss the thermal conduction mechanism. The electrical resistivity and thermal conductivity of Ge2Sb2Te5 alloy were measured from room temperature to 823 K by four-terminal and hot-strip method, respectively. With increasing temperature, the electrical resistivity increased while the thermal conductivity first decreased up to about 600 K then increased. The electronic component of the thermal conductivity was calculated from the Wiedemann-Franz law using the resistivity results. At room temperature, Ge2Sb2Te5 alloy has large electronic thermal conductivity and low lattice thermal conductivity. Bipolar diffusion contributes more to the thermal conductivity with increasing temperature. The special crystallographic structure of Ge2Sb2Te5 alloy accounts for the thermal conduction mechanism.

Electrically Conductive and Protective Coating for Planar SOFC Stacks

Energy Technology Data Exchange (ETDEWEB)

Choi, Jung-Pyung; Stevenson, Jeffry W.

2017-12-04

Ferritic stainless steels are preferred interconnect materials for intermediate temperature SOFCs because of their resistance to oxidation, high formability and low cost. However, their protective oxide layer produces Cr-containing volatile species at SOFC operating temperatures and conditions, which can cause cathode poisoning. Electrically conducting spinel coatings have been developed to prevent cathode poisoning and to maintain an electrically conductive pathway through SOFC stacks. However, this coating is not compatible with the formation of stable, hermetic seals between the interconnect frame component and the ceramic cell. Thus, a new aluminizing process has been developed by PNNL to enable durable sealing, prevent Cr evaporation, and maintain electrical insulation between stack repeat units. Hence, two different types of coating need to have stable operation of SOFC stacks. This paper will focus on the electrically conductive coating process. Moreover, an advanced coating process, compatible with a non-electrically conductive coating will be

Electrical conductivity of metal powders under pressure

Science.gov (United States)

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

2011-12-01

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

Making Complex Electrically Conductive Patterns on Cloth

Science.gov (United States)

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

2008-01-01

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

The Electrical Conductivity of Stretched Polyaniline and Polypyrrole Coated Yarns

Directory of Open Access Journals (Sweden)

M. Nouri

2009-12-01

Full Text Available The nylon and nylon/lycra yarns were coated with electrically conductive polymers such as polyaniline and polypyrrole, via chemical polymerization process. Electrical conductivity of the coated yarns was measured at variousstrain levels using two-point probe technique and their strain sensitivities were studied. The results showed that, electrical conductivity of the coated yarns decreased with an increase in strain level. A sharp decrease in the electrical conductivity of the nylon/lycra coated yarn with the strain level was recorded whereas, a small drop in the electrical conductivity of the nylon coated yarn was observed. Linear relationships were found between the electrical conductivity and length for the nylon and nylon/lycra coated yarns. The polyaniline coated yarns showed higher strain sensitivity compared to polypyrrole coated yarns. Repeatability of the strain sensitivity of the coated yarns was examined and the coated nylon/lycra yarn showed better repeatability compared to that of coated nylon yarn. The coated yarns were proposed as a flexible strain sensor in the field of intelligent materials.

Therapeutic use of fractionated total body and subtotal body irradiation

International Nuclear Information System (INIS)

Loeffler, R.K.

1981-01-01

Ninety-one patients were treated using fractionated subtotal body (STBI) or total body irradiation (TBI). These patients had generalized lymphomas, Hodgkin's disease, leukemias, myelomas, seminomas, or oat-cell carcinomas. Subtotal body irradiation is delivered to the entire body, except for the skull and extremities. It was expected that a significantly higher radiation dose could be administered with STBI than with TBI. A five- to ten-fold increase in tolerance for STBI was demonstrated. Many of these patients have had long-term emissions. There is little or no treatment-induced symptomatology, and no sanctuary sites

Conductive core of radiation-resistant high-pressure electric bushing, especially for nuclear technology

International Nuclear Information System (INIS)

Zajic, V.

1981-01-01

A radiation-resistant high-pressure electric bushing was developed featuring a conductive core consisting of a hollow moulding. At the point of attachment to the bushing insulator the core moulding is widened, thus forming a ring support of a diameter larger by at least 10% than the diameter of the conductive core cylindrical section. On the outer side of the pressure body the core cavity is narrowed and tightly closed with the conductor. On the side facing the medium of higher pressure, the conductive core is provided with a thread. Core manufacture and connection of the conductor to the bushing is very simple. The bushing can be used for an environment with pressures exceeding 10 MPa. (J.B.)

Conductive core of radiation-resistant high-pressure electric bushing, especially for nuclear technology

Energy Technology Data Exchange (ETDEWEB)

Zajic, V

1981-09-01

A radiation-resistant high-pressure electric bushing was developed featuring a conductive core consisting of a hollow moulding. At the point of attachment to the bushing insulator the core moulding is widened, thus forming a ring support of a diameter larger by at least 10% than the diameter of the conductive core cylindrical section. On the outer side of the pressure body the core cavity is narrowed and tightly closed with the conductor. On the side facing the medium of higher pressure, the conductive core is provided with a thread. Core manufacture and connection of the conductor to the bushing is very simple. The bushing can be used for an environment with pressures exceeding 10 MPa.

Correlation of electrical conductivity and photoluminescence in nanoporous silicon

International Nuclear Information System (INIS)

Bouaicha, M.; Khardani, M.; Bessais, B.

2006-01-01

The effective electrical conductivity of p type porous silicon is determined both theoretically and experimentally for different porosities ranging from 30% to 80%. In this work, Effective Medium Approximation (EMA) model was used as a theoretical support. The porous silicon samples were prepared by the electrochemical etching method for different values of the anodic current. The porous material is assumed to be formed of three phases; vacuum, oxide and Si nanocrystallites. The analytical expression of the electrical conductivity of the Si nanocrystallites was established using the quantum confinement theory. This enables us to correlate the electrical conductivity of a PS layer, to the peak energy of its photoluminescence (PL) spectrum. A perfect agreement between the theoretical and the experimental electrical conductivity values was obtained for all prospected PS porosities. The results are discussed as regard to other works

Interaction between lf electric fields and biological bodies

Directory of Open Access Journals (Sweden)

Češelkoska Vesna C.

2004-01-01

Full Text Available In this paper the Equivalent electrodes method is used for electric field calculation in the proximity of the various biological subjects exposed to an electric field in the LF range. Several results of the electric field intensity on the body surface and numerous graphical results for equipotential and equienergetic curves are presented.

Ambient effects on the electrical conductivity of carbon nanotubes

DEFF Research Database (Denmark)

Roch, Aljoscha; Greifzu, Moritz; Roch Talens, Esther

2015-01-01

We show that the electrical conductivity of single walled carbon nanotubes (SWCNT) networks is affected by oxygen and air humidity under ambient conditions by more than a magnitude. Later, we intentionally modified the electrical conductivity by functionalization with iodine and investigated...

Estimation of Total Body Fat from Potassium-40 Content

International Nuclear Information System (INIS)

Taha Mohamed Taha Ahmed, T.M.T.

2010-01-01

This paper concerns on estimation of total body fat from potassium 40 content using total body counting technique. The work performed using fast scan whole body counter. Calibration of that system for K-40 was carried out under assumption that uniformity distribution of radioactivity of potassium was distributed in 10 polyethylene bottles phantom. Different body sizes were represented by 2, 4, 6, 8 and 10 polyethylene bottles; each bottle has a volume of 0.04 m3. The counting efficiency for each body size was determined. Lean body weight (LBW) was calculated for ten males and ten females using appropriate mathematical equation. Total Body Potassium, TBK for the same selected group was measured using whole body counter. A mathematical relationship between lean body weight and potassium content was deduced .Fat contents for some individuals were calculated and weight/height ratio was indicated for fatness.

Low-frequency transient electric and magnetic fields coupling to child body

International Nuclear Information System (INIS)

Ozen, S.

2008-01-01

Much of the research related to residential electric and magnetic field exposure focuses on cancer risk for children. But until now only little knowledge about coupling of external transient electric and magnetic fields with the child's body at low frequency transients existed. In this study, current densities, in the frequency range from 50 Hz up to 100 kHz, induced by external electric and magnetic fields to child and adult human body, were investigated, as in residential areas, electric and magnetic fields become denser in this frequency band. For the calculations of induced fields and current density, the ellipsoidal body models are used. Current density induced by the external magnetic field (1 μT) and external electric field (1 V/m) is estimated. The results of this study show that the transient electric and magnetic fields would induce higher current density in the child body than power frequency fields with similar field strength. (authors)

A new method of body habitus correction for total body potassium measurements

International Nuclear Information System (INIS)

O'Hehir, S; Green, S; Beddoe, A H

2006-01-01

This paper describes an accurate and time-efficient method for the determination of total body potassium via a combination of measurements in the Birmingham whole body counter and the use of the Monte Carlo n-particle (MCNP) simulation code. In developing this method, MCNP has also been used to derive values for some components of the total measurement uncertainty which are difficult to quantify experimentally. A method is proposed for MCNP-assessed body habitus corrections based on a simple generic anthropomorphic model, scaled for individual height and weight. The use of this model increases patient comfort by reducing the need for comprehensive anthropomorphic measurements. The analysis shows that the total uncertainty in potassium weight determination by this whole body counting methodology for water-filled phantoms with a known amount of potassium is 2.7% (SD). The uncertainty in the method of body habitus correction (applicable also to phantom-based methods) is 1.5% (SD). It is concluded that this new strategy provides a sufficiently accurate model for routine clinical use

A new method of body habitus correction for total body potassium measurements

Energy Technology Data Exchange (ETDEWEB)

O' Hehir, S [University Hospital Birmingham Foundation NHS Trust, Birmingham (United Kingdom); Green, S [University Hospital Birmingham Foundation NHS Trust, Birmingham (United Kingdom); Beddoe, A H [University Hospital Birmingham Foundation NHS Trust, Birmingham (United Kingdom)

2006-09-07

This paper describes an accurate and time-efficient method for the determination of total body potassium via a combination of measurements in the Birmingham whole body counter and the use of the Monte Carlo n-particle (MCNP) simulation code. In developing this method, MCNP has also been used to derive values for some components of the total measurement uncertainty which are difficult to quantify experimentally. A method is proposed for MCNP-assessed body habitus corrections based on a simple generic anthropomorphic model, scaled for individual height and weight. The use of this model increases patient comfort by reducing the need for comprehensive anthropomorphic measurements. The analysis shows that the total uncertainty in potassium weight determination by this whole body counting methodology for water-filled phantoms with a known amount of potassium is 2.7% (SD). The uncertainty in the method of body habitus correction (applicable also to phantom-based methods) is 1.5% (SD). It is concluded that this new strategy provides a sufficiently accurate model for routine clinical use.

Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

Directory of Open Access Journals (Sweden)

L. Dai

2018-03-01

Full Text Available The electrical conductivity of gneiss samples with different chemical compositions (WA = Na2O + K2O + CaO  =  7.12, 7.27 and 7.64 % weight percent was measured using a complex impedance spectroscopic technique at 623–1073 K and 1.5 GPa and a frequency range of 10−1 to 106 Hz. Simultaneously, a pressure effect on the electrical conductivity was also determined for the WA = 7.12 % gneiss. The results indicated that the gneiss conductivities markedly increase with total alkali and calcium ion content. The sample conductivity and temperature conform to an Arrhenius relationship within a certain temperature range. The influence of pressure on gneiss conductivity is weaker than temperature, although conductivity still increases with pressure. According to various ranges of activation enthalpy (0.35–0.52 and 0.76–0.87 eV at 1.5 GPa, two main conduction mechanisms are suggested that dominate the electrical conductivity of gneiss: impurity conduction in the lower-temperature region and ionic conduction (charge carriers are K+, Na+ and Ca2+ in the higher-temperature region. The electrical conductivity of gneiss with various chemical compositions cannot be used to interpret the high conductivity anomalies in the Dabie–Sulu ultrahigh-pressure metamorphic belt. However, the conductivity–depth profiles for gneiss may provide an important constraint on the interpretation of field magnetotelluric conductivity results in the regional metamorphic belt.

Electrical conductivity of (La,Sr)MnO3

International Nuclear Information System (INIS)

Nowotny, J.; Rekas, M.; Sorrell, C.C.

1998-01-01

Defect disorder model for undoped and Sr-doped LaMnO 3 was derived from non-stoichiometry data reported in literature. This model is checked against the electrical conductivity data. The regimes corresponding to oxygen deficit and oxygen excess will be discussed. A good agreement between the random defect model and experimental data of the electrical conductivity was revealed. Copyright (1998) Australasian Ceramic Society

Experimental evaluation of electrical conductivity imaging of anisotropic brain tissues using a combination of diffusion tensor imaging and magnetic resonance electrical impedance tomography

Energy Technology Data Exchange (ETDEWEB)

Sajib, Saurav Z. K.; Jeong, Woo Chul; Oh, Tong In; Kim, Hyung Joong, E-mail: bmekim@khu.ac.kr, E-mail: ejwoo@khu.ac.kr; Woo, Eung Je, E-mail: bmekim@khu.ac.kr, E-mail: ejwoo@khu.ac.kr [Department of Biomedical Engineering, Kyung Hee University, Seoul 02447 (Korea, Republic of); Kyung, Eun Jung [Department of Pharmacology, Chung-Ang University, Seoul 06974 (Korea, Republic of); Kim, Hyun Bum [Department of East-West Medical Science, Kyung Hee University, Yongin 17104 (Korea, Republic of); Kwon, Oh In [Department of Mathematics, Konkuk University, Seoul 05029 (Korea, Republic of)

2016-06-15

Anisotropy of biological tissues is a low-frequency phenomenon that is associated with the function and structure of cell membranes. Imaging of anisotropic conductivity has potential for the analysis of interactions between electromagnetic fields and biological systems, such as the prediction of current pathways in electrical stimulation therapy. To improve application to the clinical environment, precise approaches are required to understand the exact responses inside the human body subjected to the stimulated currents. In this study, we experimentally evaluate the anisotropic conductivity tensor distribution of canine brain tissues, using a recently developed diffusion tensor-magnetic resonance electrical impedance tomography method. At low frequency, electrical conductivity of the biological tissues can be expressed as a product of the mobility and concentration of ions in the extracellular space. From diffusion tensor images of the brain, we can obtain directional information on diffusive movements of water molecules, which correspond to the mobility of ions. The position dependent scale factor, which provides information on ion concentration, was successfully calculated from the magnetic flux density, to obtain the equivalent conductivity tensor. By combining the information from both techniques, we can finally reconstruct the anisotropic conductivity tensor images of brain tissues. The reconstructed conductivity images better demonstrate the enhanced signal intensity in strongly anisotropic brain regions, compared with those resulting from previous methods using a global scale factor.

Synthesis and characterization of electrical conducting nanoporous carbon structures

International Nuclear Information System (INIS)

El Mir, L.; Kraiem, S.; Bengagi, M.; Elaloui, E.; Ouederni, A.; Alaya, S.

2007-01-01

Nanoporous organic xerogel compounds were prepared by sol-gel method from pyrogallol-formaldehyde (PF) mixtures in water using perchloric acid as catalyst. The preparation conditions of electrical conducting carbon (ECC) structures were explored by changing the pyrolysis temperature. The effect of this preparation parameters on the structural and electrical properties of the obtained ECCs were studied, respectively, by thermogravimetric analysis (TGA), nitrogen adsorption isotherms, IR spectroscopy and electrical conductivity measurements. The analysis of the obtained results revealed that, the polymeric insulating phase was transformed progressively with pyrolysis temperature into carbon conducting phase; this means the formation of long continuous conducting path for charge carriers when the carbon microparticles inside the structure agglomerated with thermal treatment and the samples exhibited tangible percolation behaviour where the percolation threshold can be determined by pyrolysis temperature. The temperature-dependent conductivity and the I(V) characteristics of the obtained ECC structures show a non-ohmic behaviour. The results obtained from TGA and differential thermal analyser (DTA) thermograms, scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs, IR spectroscopy and X-ray diffraction revealed that, the obtained ECC structures consist of amorphous and nanoporous electrical conducting carbon materials

Electrical conductivity measurement on DKDP Crystals with different deuterated degrees

International Nuclear Information System (INIS)

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

2012-01-01

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

Transport properties of olivine grain boundaries from electrical conductivity experiments

Science.gov (United States)

Pommier, Anne; Kohlstedt, David L.; Hansen, Lars N.; Mackwell, Stephen; Tasaka, Miki; Heidelbach, Florian; Leinenweber, Kurt

2018-05-01

Grain boundary processes contribute significantly to electronic and ionic transports in materials within Earth's interior. We report a novel experimental study of grain boundary conductivity in highly strained olivine aggregates that demonstrates the importance of misorientation angle between adjacent grains on aggregate transport properties. We performed electrical conductivity measurements of melt-free polycrystalline olivine (Fo90) samples that had been previously deformed at 1200 °C and 0.3 GPa to shear strains up to γ = 7.3. The electrical conductivity and anisotropy were measured at 2.8 GPa over the temperature range 700-1400 °C. We observed that (1) the electrical conductivity of samples with a small grain size (3-6 µm) and strong crystallographic preferred orientation produced by dynamic recrystallization during large-strain shear deformation is a factor of 10 or more larger than that measured on coarse-grained samples, (2) the sample deformed to the highest strain is the most conductive even though it does not have the smallest grain size, and (3) conductivity is up to a factor of 4 larger in the direction of shear than normal to the shear plane. Based on these results combined with electrical conductivity data for coarse-grained, polycrystalline olivine and for single crystals, we propose that the electrical conductivity of our fine-grained samples is dominated by grain boundary paths. In addition, the electrical anisotropy results from preferential alignment of higher-conductivity grain boundaries associated with the development of a strong crystallographic preferred orientation of the grains.

Mechanisms of electrical conductivity in olivine

International Nuclear Information System (INIS)

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

1984-01-01

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

Electrical conductivity of cobalt–titanium substituted SrCaM hexaferrites

International Nuclear Information System (INIS)

Eraky, M.R.

2012-01-01

A series of polycrystalline M-type hexagonal ferrites with the composition Sr 0.5 Ca 0.5 Co x Ti x Fe 12−2x O 19 (where x=0.0–0.8) were prepared by the conventional ceramic technique. The electrical conductivity has been measured from 300 to 590 K. The dc conductivity, σ dc , exhibited a semiconductor behavior. The negative sign of thermoelectric power coefficient S reveals that all samples are n-type semiconductors. Both σ dc and mobility, μ d , increases with the substitution of Co 2+ and Ti 4+ ions, reach maximum at x=0.4 and start decreasing at x>0.4. Many conduction mechanisms were discussed to explain the electric conduction in the system. It was found that the hopping conduction is the predominant conduction mechanism. For samples with compositional parameter x=0.0 and 0.8, the band conduction mechanism shares in electric conduction beside the hopping process. - Highlights: ► SrCaCoTiM hexaferrites have been prepared by conventional ceramic technique. ► The electrical conductivity exhibited a semiconductor behavior. There is an increase in conductivity up to x=0.4 for Co and Ti substitution. ► The hopping conduction is the predominant conduction mechanism.

Electrical Conductivity in Transition Metals

Science.gov (United States)

Talbot, Christopher; Vickneson, Kishanda

2013-01-01

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

Electrical conduction in solid materials physicochemical bases and possible applications

CERN Document Server

Suchet, J P

2013-01-01

Electrical Conduction in Solid Materials (Physicochemical Bases and Possible Applications) investigates the physicochemical bases and possible applications of electrical conduction in solid materials, with emphasis on conductors, semiconductors, and insulators. Topics range from the interatomic bonds of conductors to the effective atomic charge in conventional semiconductors and magnetic transitions in switching semiconductors. Comprised of 10 chapters, this volume begins with a description of electrical conduction in conductors and semiconductors, metals and alloys, as well as interatomic bon

A percolation approach to study the high electric field effect on electrical conductivity of insulating polymer

Science.gov (United States)

Benallou, Amina; Hadri, Baghdad; Martinez-Vega, Juan; El Islam Boukortt, Nour

2018-04-01

The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework.

Magnetohydraulic flow through a packed bed of electrically conducting spheres

International Nuclear Information System (INIS)

Sanders, T.L.

1985-01-01

The flow of an electrically conducting fluid through a packed bed of electrically conducting spheres in the presence of a strong magnetic field constitutes a very complex flow situation due to the constant turning of the fluid in and out of magnetic field lines. The interaction of the orthogonal components of the velocity and magnetic field will induce electric fields that are orthogonal to both and the electric fields in turn can cause currents that interact with the magnetic field to generate forces against the direction of flow. The strengths of these generated forces depend primarily upon the closure paths taken by the induced currents which, in turn, depend upon the relative ratio of the electrical resistance of the solid spheres to that of the fluid. Both experimental and analytical analyses of the slow flow of a eutectic mixture of sodium and potassium (NaK) through packed cylinders containing stainless steel spheres in the presence of a strong transverse magnetic field were completed. A theory of magnetohydraulic flow is developed by analogy with the development of hydraulic radius theories of flow through porous media. An exact regional analysis is successfully applied to an infinite bed of electrically conducting spheres with a conducting or non-conducting constraining wall on one side. The equations derived are solved for many different combinations of flowrate, magnetic field strength, porosity, and electrical resistance ratio

Evaluation of Soft Tissue Sarcoma Tumors Electrical Conductivity Anisotropy Using Diffusion Tensor Imaging for Numerical Modeling on Electroporation

Directory of Open Access Journals (Sweden)

Ghazikhanlou-sani K.

2016-06-01

Full Text Available Introduction: There is many ways to assessing the electrical conductivity anisotropy of a tumor. Applying the values of tissue electrical conductivity anisotropy is crucial in numerical modeling of the electric and thermal field distribution in electroporation treatments. This study aims to calculate the tissues electrical conductivity anisotropy in patients with sarcoma tumors using diffusion tensor imaging technique. Materials and Method: A total of 3 subjects were involved in this study. All of patients had clinically apparent sarcoma tumors at the extremities. The T1, T2 and DTI images were performed using a 3-Tesla multi-coil, multi-channel MRI system. The fractional anisotropy (FA maps were performed using the FSL (FMRI software library software regarding the DTI images. The 3D matrix of the FA maps of each area (tumor, normal soft tissue and bone/s was reconstructed and the anisotropy matrix was calculated regarding to the FA values. Result: The mean FA values in direction of main axis in sarcoma tumors were ranged between 0.475–0.690. With assumption of isotropy of the electrical conductivity, the FA value of electrical conductivity at each X, Y and Z coordinate axes would be equal to 0.577. The gathered results showed that there is a mean error band of 20% in electrical conductivity, if the electrical conductivity anisotropy not concluded at the calculations. The comparison of FA values showed that there is a significant statistical difference between the mean FA value of tumor and normal soft tissues (P<0.05. Conclusion: DTI is a feasible technique for the assessment of electrical conductivity anisotropy of tissues. It is crucial to quantify the electrical conductivity anisotropy data of tissues for numerical modeling of electroporation treatments.

Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

Science.gov (United States)

Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

2015-02-01

In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3)  S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. Copyright © 2014 John Wiley & Sons, Ltd.

Method of imaging the electrical conductivity distribution of a subsurface

Science.gov (United States)

Johnson, Timothy C.

2017-09-26

A method of imaging electrical conductivity distribution of a subsurface containing metallic structures with known locations and dimensions is disclosed. Current is injected into the subsurface to measure electrical potentials using multiple sets of electrodes, thus generating electrical resistivity tomography measurements. A numeric code is applied to simulate the measured potentials in the presence of the metallic structures. An inversion code is applied that utilizes the electrical resistivity tomography measurements and the simulated measured potentials to image the subsurface electrical conductivity distribution and remove effects of the subsurface metallic structures with known locations and dimensions.

Maximum on the electrical conductivity polytherm of molten TeCl4

International Nuclear Information System (INIS)

Salyulev, Alexander B.; Potapov, Alexei M.

2017-01-01

The electrical conductivity of molten TeCl 4 was measured up to 761 K, i.e. 106 degrees above the normal boiling point of the salt. For the first time it was found that TeCl 4 electrical conductivity polytherm has a maximum. It was recorded at 705 K (Κ max =0.245 Sm/cm), whereupon the conductivity decreases as the temperature rises. The activation energy of electrical conductivity was calculated.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

In vivo electrical conductivity imaging of a canine brain using a 3 T MREIT system

International Nuclear Information System (INIS)

Kim, Hyung Joong; Oh, Tong In; Kim, Young Tae; Lee, Byung Il; Woo, Eung Je; Lee, Soo Yeol; Seo, Jin Keun; Kwon, Ohin; Park, Chunjae; Kang, Byeong Teck; Park, Hee Myung

2008-01-01

Magnetic resonance electrical impedance tomography (MREIT) aims at producing high-resolution cross-sectional conductivity images of an electrically conducting object such as the human body. Following numerous phantom imaging experiments, the most recent study demonstrated successful conductivity image reconstructions of postmortem canine brains using a 3 T MREIT system with 40 mA imaging currents. Here, we report the results of in vivo animal imaging experiments using 5 mA imaging currents. To investigate any change of electrical conductivity due to brain ischemia, canine brains having a regional ischemic model were scanned along with separate scans of canine brains having no disease model. Reconstructed multi-slice conductivity images of in vivo canine brains with a pixel size of 1.4 mm showed a clear contrast between white and gray matter and also between normal and ischemic regions. We found that the conductivity value of an ischemic region decreased by about 10–14%. In a postmortem brain, conductivity values of white and gray matter decreased by about 4–8% compared to those in a live brain. Accumulating more experience of in vivo animal imaging experiments, we plan to move to human experiments. One of the important goals of our future work is the reduction of the imaging current to a level that a human subject can tolerate. The ability to acquire high-resolution conductivity images will find numerous clinical applications not supported by other medical imaging modalities. Potential applications in biology, chemistry and material science are also expected

An electrical method for the measurement of the thermal and electrical conductivity of reduced graphene oxide nanostructures.

Science.gov (United States)

Schwamb, Timo; Burg, Brian R; Schirmer, Niklas C; Poulikakos, Dimos

2009-10-07

This paper introduces an electrical four-point measurement method enabling thermal and electrical conductivity measurements of nanoscale materials. The method was applied to determine the thermal and electrical conductivity of reduced graphene oxide flakes. The dielectrophoretically deposited samples exhibited thermal conductivities in the range of 0.14-2.87 W m(-1) K(-1) and electrical conductivities in the range of 6.2 x 10(2)-6.2 x 10(3) Omega(-1) m(-1). The measured properties of each flake were found to be dependent on the duration of the thermal reduction and are in this sense controllable.

Electrical conductivity of hydrogen shocked to megabar pressures

International Nuclear Information System (INIS)

Weir, S.T.; Nellis, W.J.; Mitchell, A.C.

1993-08-01

The properties of ultra-high pressure hydrogen have been the subject of much experimental and theoretical study. Of particular interest is the pressure-induced insulator-to-metal transition of hydrogen which, according to recent theoretical calculations, is predicted to occur by band-overlap in the pressure range of 1.5-3.0 Mbars on the zero temperature isotherm. Extremely high pressures are required for metallization since the low-pressure band gap is about 15 eV. Recent static-pressure diamond anvil cell experiments have searched for evidence of an insulator-to-metal transition, but no conclusive evidence for such a transition has yet been supplied. Providing conclusive evidence for hydrogen metallization is difficult because no technique has yet been developed for performing static high-pressure electrical conductivity experiments at megabar pressures. The authors report here on electrical conductivity experiments performed on H 2 and D 2 multi-shocked to megabar pressures. Electrical conductivities of dense fluid hydrogen at these pressures and temperatures reached are needed for calculations of the magnetic fields of Jupiter and Saturn, the magnetic fields being generated by convective dynamos of hot, dense, semiconducting fluid hydrogen. Also, since electrical conduction at the pressure-temperature conditions being studied is due to the thermal excitation of charge carriers across the electronic band gap, these experiments yield valuable information on the width of the band gap at high densities

Electrically conductive biodegradable polymer composite for nerve regeneration: electricity-stimulated neurite outgrowth and axon regeneration.

Science.gov (United States)

Zhang, Ze; Rouabhia, Mahmoud; Wang, Zhaoxu; Roberge, Christophe; Shi, Guixin; Roche, Phillippe; Li, Jiangming; Dao, Lê H

2007-01-01

Normal and electrically stimulated PC12 cell cultures and the implantation of nerve guidance channels were performed to evaluate newly developed electrically conductive biodegradable polymer composites. Polypyrrole (PPy) doped by butane sulfonic acid showed a significantly higher number of viable cells compared with PPy doped by polystyrenesulfonate after a 6-day culture. The PC12 cells were left to proliferate for 6 days, and the PPy-coated membranes, showing less initial cell adherence, recorded the same proliferation rate as did the noncoated membranes. Direct current electricity at various intensities was applied to the PC12 cell-cultured conductive membranes. After 7 days, the greatest number of neurites appeared on the membranes with a current intensity approximating 1.7-8.4 microA/cm. Nerve guidance channels made of conductive biodegradable composite were implanted into rats to replace 8 mm of sciatic nerve. The implants were harvested after 2 months and analyzed with immunohistochemistry and transmission electron microscopy. The regenerated nerve tissue displayed myelinated axons and Schwann cells that were similar to those in the native nerve. Electrical stimulation applied through the electrically conductive biodegradable polymers therefore enhanced neurite outgrowth in a current-dependent fashion. The conductive polymers also supported sciatic nerve regeneration in rats.

Electrical insulation and conduction coating for fusion experimental devices

International Nuclear Information System (INIS)

Onozuka, Masanori; Tsujimura, Seiji; Toyoda, Masahiko; Inoue, Masahiko; Abe, Tetsuya; Murakami, Yoshio

1996-01-01

The development of electrical insulation and conduction coating methods that can be applied to large components of fusion experimental devices has been investigated. A thermal spraying method is used to coat the insulation or conduction materials on the structural components because of its applicability for large surfaces. The insulation material chosen was Al 2 O 3 , while Cr 3 C 2 -NiCr and WC-NiCr were chosen as conduction materials. These materials were coated on stainless steel substrates to examine the basic characteristics of the coated layers, such as their adhesive strength to the substrate, thermal shock resistance, electrical resistance, dielectric breakdown voltage, and thermal conductivity. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed adequate frictional properties. The spraying method was tested on a 100- x 1000-mm surface and found to be applicable for large surfaces of experimental fusion devices. 9 refs., 6 figs., 15 tabs

A nonconjugated radical polymer glass with high electrical conductivity

Science.gov (United States)

Joo, Yongho; Agarkar, Varad; Sung, Seung Hyun; Savoie, Brett M.; Boudouris, Bryan W.

2018-03-01

Solid-state conducting polymers usually have highly conjugated macromolecular backbones and require intentional doping in order to achieve high electrical conductivities. Conversely, single-component, charge-neutral macromolecules could be synthetically simpler and have improved processibility and ambient stability. We show that poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a nonconjugated radical polymer with a subambient glass transition temperature, underwent rapid solid-state charge transfer reactions and had an electrical conductivity of up to 28 siemens per meter over channel lengths up to 0.6 micrometers. The charge transport through the radical polymer film was enabled with thermal annealing at 80°C, which allowed for the formation of a percolating network of open-shell sites in electronic communication with one another. The electrical conductivity was not enhanced by intentional doping, and thin films of this material showed high optical transparency.

In-vivo determination of total body water and lean body mass in subjects by deuterium dilution

International Nuclear Information System (INIS)

Blagojevic, N.; Allen, B.J.; Baur, L.; Gaskin, K.

1988-01-01

Total body water (TBW) estimation is one of a number of basic techniques required for the determination of body composition in normal and malnourished subjects. When combined with total body nitrogen (TBN) analysis by prompt gamma neutron activation, an accurate compartmental model of in vivo body composition can be formed, providing valuable nutritional and other data. This study examines the role of TBW on its own in evaluating lean body mass. Total body water was studied in six male and five female subjects using deuterium oxide and a Fourier transform infrared spectrometer. The lean body mass calculated from the results was compared with the lean body mass deduced from established total body nitrogen measurements. A four-compartment model was also used to calculate lean body mass. Excellent agreement was shown between lean body mass derived from TBW, the four-compartment model and TBN. Hence, TBW can provide a fast, cost-efficient method for evaluating normal subjects. However, for disease-induced malnutrition, or highly developed athletes, both TBN and TBW measurements are essential to establish an accurate picture of their body composition. TBW measurements alone can monitor the hydration state of patients and as such have a useful diagnostic value

In-vivo determination of total body water and lean body mass in subjects by deuterium dilution

Energy Technology Data Exchange (ETDEWEB)

Blagojevic, N; Allen, B J; Baur, L; Gaskin, K

1988-12-01

Total body water (TBW) estimation is one of a number of basic techniques required for the determination of body composition in normal and malnourished subjects. When combined with total body nitrogen (TBN) analysis by prompt gamma neutron activation, an accurate compartmental model of in vivo body composition can be formed, providing valuable nutritional and other data. This study examines the role of TBW on its own in evaluating lean body mass. Total body water was studied in six male and five female subjects using deuterium oxide and a Fourier transform infrared spectrometer. The lean body mass calculated from the results was compared with the lean body mass deduced from established total body nitrogen measurements. A four-compartment model was also used to calculate lean body mass. Excellent agreement was shown between lean body mass derived from TBW, the four-compartment model and TBN. Hence, TBW can provide a fast, cost-efficient method for evaluating normal subjects. However, for disease-induced malnutrition, or highly developed athletes, both TBN and TBW measurements are essential to establish an accurate picture of their body composition. TBW measurements alone can monitor the hydration state of patients and as such have a useful diagnostic value.

Electrical Impedance Spectroscopy for Electro-Mechanical Characterization of Conductive Fabrics

Directory of Open Access Journals (Sweden)

Tushar Kanti Bera

2014-06-01

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

Modelling electrical conductivity of groundwater using and adaptive neuro-fuzzy inference system

NARCIS (Netherlands)

Tutmez, B.; Hatipoglu, Z.; Kaymak, U.

2006-01-01

Electrical conductivity is an important indicator for water quality assessment. Since the composition of mineral salts affects the electrical conductivity of groundwater, it is important to understand the relationships between mineral salt composition and electrical conductivity. In this present

Modelling electrical conductivity of groundwater using an adaptive neuro-fuzzy inference system

NARCIS (Netherlands)

B. Tutmez (Bulent); Z. Hatipoglu (Z.); U. Kaymak (Uzay)

2006-01-01

textabstractElectrical conductivity is an important indicator for water quality assessment. Since the composition of mineral salts affects the electrical conductivity of groundwater, it is important to understand the relationships between mineral salt composition and electrical conductivity. In this

Behaviour of the Egyptian beach economic minerals during their electrical separation in relation to their electrical conductivity

International Nuclear Information System (INIS)

Khazback, A.E.; Soliman, F.A.S.

1988-01-01

The most important and strategic minerals in the Egyptian beach sands are monazite, zircon, rutile and ilmenite. Due to their importance, several flowsheets were designed for their separation economically. Electrostatic separation plays an important role in most of these flowsheets depending on the main differences between them concerning their electrical conductivity. This paper describes the design of a cell for the measurement of the electrical conductivities of these minerals. It also establishes a quantitative relationship between the electrical conductivity and the behaviour of these minerals during their electrical separation. A computer program was written to facilitate the calculation of the slope of the discharge curve from which the electrical conductivity or the reciprocal resistivity. Relaxation time and the data correlation coefficient for the tested minerals are obtained. For all the tests performed, the correlation coefficient value was found to be better than 99%. In general the electrical conductivity was shown to be a function of both temperature and grain size. It was found also that the presence of iron staining on the surface of monazite grains and inclusions in the zircon grains alters noticeably the bulk conductivity of the tested minerals

Acute tolerance of hyperfractionated accelerated total body irradiation

International Nuclear Information System (INIS)

Latz, D.; Schraube, P.; Wannenmacher, M.

1996-01-01

Background: Acute side effects of total body irradiation lead to intense molestations of the patients. Therefore, it is desirable to take measures to reduce these side effects. In a retrospective study the frequency on acute side effects of a hyperfractionated accelerated total body irradiation was assessed and compared to frequencies of other exposure schedules published in the literature. Additionally the influence of ondansetron on the frequency of nausea and vormiting was investigated. Patients and Method: From 1989 to 1992, 76 patients (47 male, 29 female; median age 38 years) underwent total body irradiation before autologeous bone marrow transplantation. They received 3 daily doses of 1.20 Gy each every 4 h on 4 successive days to a total dose of 14,40 Gy. Thirty-nine patients received 3x8 mg (daily, intravenous or per os) ondansetron during the whole course of irradiation. Results: The most relevant side effects were nausea and vomiting. Patients, who did not receive ondansetron (n=37) showed a nausea and emesis rate of 73%. With ondansetron (n=39) nausea and emesis were reduced to 38%. Also the grade of severity of these side effects was reduced. Conclusions: Ondansetron proved to be an effective medicament for relieving nausea and vormiting during total body irradiation. The results obtained are in concordance with those published in the literature. (orig.) [de

Universality of DC electrical conductivity from holography

Energy Technology Data Exchange (ETDEWEB)

Ge, Xian-Hui, E-mail: gexh@shu.edu.cn [Shanghai Key Laboratory of High Temperature Superconductors, Department of Physics, Shanghai University, Shanghai, 200444 (China); Department of Physics, University of California, San Diego, CA92122 (United States); Sin, Sang-Jin, E-mail: sjsin@hangyang.ac.kr [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Wu, Shao-Feng, E-mail: sfwu@shu.edu.cn [Department of Physics, Shanghai University, Shanghai, 200444 (China)

2017-04-10

We propose a universal formula of dc electrical conductivity in rotational- and translational-symmetries breaking systems via the holographic duality. This formula states that the ratio of the determinant of the dc electrical conductivities along any spatial directions to the black hole area density in zero-charge limit has a universal value. As explicit illustrations, we give several examples elucidating the validation of this formula: We construct an anisotropic black brane solution, which yields linear in temperature for the in-plane resistivity and insulating behavior for the out-of-plane resistivity; We also construct a spatially isotropic black brane solution that both the linear-T and quadratic-T contributions to the resistivity can be realized.

Simplified Calculation of the Electrical Conductivity of Composites with Carbon Nanotubes

Science.gov (United States)

Ivanov, S. G.; Aniskevich, A.; Kulakov, V.

2018-03-01

The electrical conductivity of two groups of polymer nanocomposites filled with the same NC7000 carbon nanotubes (CNTs) beyond the percolation threshold is described with the help of simple formulas. Different manufacturing process of the nanocomposites led to different CNT network structures, and, as a consequence, their electrical conductivity, at the same CNT volume, differed by two orders of magnitude. The relation between the electrical conductivity and the volume content of CNTs of the first group of composites (with a higher electrical conductivity) is described assuming that the CNT network structure is close to a statistically homogeneous one. The formula for this case, derived on the basis of a self-consistent model, includes only two parameters: the effective longitudinal electrical conductivity of CNT and the percolation threshold (the critical value of CNT volume content). These parameters were determined from two experimental points of electrical conductivity as a function of the volume fraction of CNTs. The second group of nanocomposites had a pronounced agglomerative structure, which was confirmed by microscopy data. To describe the low electrical conductivity of this group of nanocomposites, a formula based on known models of micromechanics is proposed. Two parameters of this formula were determined from experimental data of the first group, but the other two — of the second group of nanocomposites. A comparison of calculation and experimental relations confirmed the practical expediency of using the approach described.

Effects of Environmental Factors and Metallic Electrodes on AC Electrical Conduction Through DNA Molecule.

Science.gov (United States)

Abdalla, S; Obaid, A; Al-Marzouki, F M

2017-12-01

function of temperature and frequency. Furthermore, in order to explain these data, we present a model describing the electrical conduction through DNA molecule: DNA is a classical semiconductor with charges, dipoles and ions that result in creation of localized energy-states (LESs) in the extended bands and in the energy gap of the DNA molecule. This model explains clearly the mechanism of charge transfer mechanism in the DNA, and it sheds light on why the charge transfer through the DNA can lead to insulating, semiconducting, or metallic behavior on the same time. The model considers charges on DNA, in the extended bands, either could be free to move under electric field or localized in potential wells/hills. Localization of charges in DNA is an intrinsic structural-property of this solitaire molecule. At all temperatures, the expected increase in thermal-induced charge is attributed to the delocalization of holes (or/and electrons) in potential hills (or/and potential wells) which accurately accounts for the total electric and dielectric behavior through DNA molecule. We succeeded to fit the experimental data to the proposed model with reasonable magnitudes of potential hills/wells that are in the energy range from 0.068 eV.

New conducted electrical weapons: Electrical safety relative to relevant standards.

Science.gov (United States)

Panescu, Dorin; Nerheim, Max; Kroll, Mark W; Brave, Michael A

2017-07-01

We have previously published about TASER ® conducted electrical weapons (CEW) compliance with international standards. CEWs deliver electrical pulses that can inhibit a person's neuromuscular control or temporarily incapacitate. An eXperimental Rotating-Field (XRF) waveform CEW and the X2 CEW are new 2-shot electrical weapon models designed to target a precise amount of delivered charge per pulse. They both can deploy 1 or 2 dart pairs, delivered by 2 separate cartridges. Additionally, the XRF controls delivery of incapacitating pulses over 4 field vectors, in a rotating sequence. As in our previous study, we were motivated by the need to understand the cardiac safety profile of these new CEWs. The goal of this paper is to analyze the nominal electrical outputs of TASER XRF and X2 CEWs in reference to provisions of all relevant international standards that specify safety requirements for electrical medical devices and electrical fences. Although these standards do not specifically mention CEWs, they are the closest electrical safety standards and hence give very relevant guidance. The outputs of several TASER XRF and X2 CEWs were measured under normal operating conditions. The measurements were compared against manufacturer specifications. CEWs electrical output parameters were reviewed against relevant safety requirements of UL 69, IEC 60335-2-76 Ed 2.1, IEC 60479-1, IEC 60479-2, AS/NZS 60479.1, AS/NZS 60479.2, IEC 60601-1 and BS EN 60601-1. Our study confirmed that the nominal electrical outputs of TASER XRF and X2 CEWs lie within safety bounds specified by relevant standards.

The electric conductivity of some forms of sintered synthetic zeolites

International Nuclear Information System (INIS)

Susic, M.; Petrovic, V.; Ristic, M.; Petranovic, N.

1978-01-01

Some forms of synthetic zeolites were sintered and their electric conductivity was measured. The conductivity was observed in correlation with the conductivity of non-sintered pressed samples. Also the change in microstructural constituents in the course of the process of sintering was observed with an optical microscope. It has been found that there is a considerable change in conductivity due to sintering as well as a change in the activation energy for conduction. Also the porosity is noticeably changed. A marked affect of the nature of counter ions on the electric conductivity is shown

Electrical and Electrochemical Properties of Conducting Polymers

Directory of Open Access Journals (Sweden)

Thanh-Hai Le

2017-04-01

Full Text Available Conducting polymers (CPs have received much attention in both fundamental and practical studies because they have electrical and electrochemical properties similar to those of both traditional semiconductors and metals. CPs possess excellent characteristics such as mild synthesis and processing conditions, chemical and structural diversity, tunable conductivity, and structural flexibility. Advances in nanotechnology have allowed the fabrication of versatile CP nanomaterials with improved performance for various applications including electronics, optoelectronics, sensors, and energy devices. The aim of this review is to explore the conductivity mechanisms and electrical and electrochemical properties of CPs and to discuss the factors that significantly affect these properties. The size and morphology of the materials are also discussed as key parameters that affect their major properties. Finally, the latest trends in research on electrochemical capacitors and sensors are introduced through an in-depth discussion of the most remarkable studies reported since 2003.

Electrical conductivity in polyacrylonitrile and perbunan

International Nuclear Information System (INIS)

Migahed, M.D.; Bakr, N.A.; Tawansi, A.

1981-07-01

The electrical conduction in Ag-PAN-Ag and Ag-NBR-Ag sandwich samples is studied measuring the dependence of current on the applied voltage and temperature. The conduction mechanism depends on the polymer type. A bulk polarization contribution is suggested in the conduction mechanism at high temperatures besides the Schottky emission in the case of PAN and simple carrier jump model in the case of NBR at room temperature. NBR(28) is proved to be more semiconducting than both NBR(38) and PAN. This is attributed to the lowering of the nitrile group content in NBR(28). (author)

Electrical conductivity in random alloys

International Nuclear Information System (INIS)

Mookerjee, A.; Thakur, P.K.; Yussouff, M.

1984-12-01

Based on the augmented space formalism introduced by one of us and the use of the Ward identity and the Bethe-Sapeter equation, a formalism has been developed for the calculation of electrical conductivity for random alloys. A simple application is made to a model case, and it is argued that the formalism enables us to carry out viable calculations on more realistic models of alloys. (author)

Electrical conductivity in random alloys

International Nuclear Information System (INIS)

Mookerjee, A.; Yussouff, M.

1983-06-01

Starting from the augmented space formalism by one of us, and the use of the Ward identity and Bethe Salpeter equation, a complete formalism for the calculation of the electrical conductivity in tight-binding models of random binary alloys has been developed. The formalism is practical in the sense that viable calculations may be carried out with its help for realistics models of alloy systems. (author)

Studies on phase evolution and electrical conductivity of barium doped gadolinium aluminate

International Nuclear Information System (INIS)

Sinha, Amit; Sharma, B.P.; Gopalan, P.

2012-01-01

Highlights: ► Barium doped GdAlO 3 compositions were prepared from citrate gel derived powders. ► The solid solubility of barium in GdAlO 3 was less than 4 mol%. ► The un-dissolved barium precipitated in the form of BaAl 2 O 4 phase. ► The conductivity of Ba-doped GdAlO 3 increased with increasing amounts of Ba. ► In Gd 1−x Ba x AlO 3−δ system, specimen with x = 0.02 exhibited maximum conductivity. - Abstract: The phase evolution and electrical conductivity of barium doped GdAlO 3 samples have been investigated. The Ba- doped compositions of GdAlO 3 were prepared through citrate gel process. Analysis of the phases was carried out using X-ray diffraction (XRD). The morphology of the calcined powders was studied by scanning electron microscopy. The electrical conductivity of Gd 1−x Ba x AlO 3−δ (x = 0–0.04) was measured using ac impedance spectroscopy as a function of temperature ranging from 300 to 1000 °C under air. The solid solubility of barium in GdAlO 3 was found to be less than 4 mol%. The undissolved barium precipitated in the form of BaAl 2 O 4 phase. The barium doped GdAlO 3 powders obtained after calcination at 1000 °C was found to be porous agglomerate composed of nanocrystalline grains. The total electrical conductivity of Ba-doped GdAlO 3 increased with increasing amounts of barium up to 2 mol% doping.

Impact of electrical conductivity on acid hydrolysis of guar gum under induced electric field.

Science.gov (United States)

Li, Dandan; Zhang, Yao; Yang, Na; Jin, Zhengyu; Xu, Xueming

2018-09-01

This study aimed to improve induced electric field (IEF)-assisted hydrolysis of polysaccharide by controlling electrical conductivity. As the conductivity of reaction medium was increased, the energy efficiency of IEF was increased because of deceased impedance, as well as enhanced output voltage and temperature, thus the hydrolysis of guar gum (GG) was accelerated under IEF. Changes in weight-average molecular weight (Mw) suggested that IEF-assisted hydrolysis of GG could be described by the first-order kinetics 1/Mw ∝ kt, with the rate constant (k), varying directly with the medium conductivity. Although IEF-assisted hydrolysis largely disrupted the morphological structure of GG, it had no impact on the chemical structure. In comparison to native GG, the steady shear viscosity of hydrolyzed GG dramatically declined while the thermal stability slightly decreased. This study extended the knowledge of electrical conductivity upon IEF-assisted acid hydrolysis of GG and might contribute to a better utilization of IEF for polysaccharide modification. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electric Conductivity of Phosphorus Nanowires

International Nuclear Information System (INIS)

Jing-Xiang, Zhang; Hui, Li; Xue-Qing, Zhang; Kim-Meow, Liew

2009-01-01

We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I – V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. (condensed matter: structure, mechanical and thermal properties)

Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

Science.gov (United States)

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

2009-01-01

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

Electrical conduction along dislocations in plastically deformed GaN

Energy Technology Data Exchange (ETDEWEB)

Kamimura, Y; Yokoyama, T; Oiwa, H; Edagawa, K [Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Yonenaga, I, E-mail: yasushi@iis.u-tokyo.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan)

2009-07-15

Electrical conduction along dislocations in plastically deformed n-GaN single crystals has been investigated by scanning spread resistance microscopy (SSRM). In the SSRM images, many conductive spots have been observed, which correspond to electrical conduction along the dislocations introduced by deformation. Here, the introduced dislocations are b=(a/3)<1overline 210> edge dislocations parallel to the [0001] direction. The current values at the spots normalized to the background current value are larger than 100. Previous works have shown that grown-in edge dislocations in GaN are nonconductive. The high conductivity of the deformation-introduced edge dislocations in the present work suggests that the conductivity depends sensitively on the dislocation core structure.

Electrical conductivity and magnetic permeability measurement of case hardened steels

Science.gov (United States)

Tian, Yong

2015-03-01

For case carburized steels, electrical conductivity and magnetic permeability profiles are needed to develop model-based case depth characterization techniques for the purpose of nondestructive quality control. To obtain fast and accurate measurement of these material properties, four-point potential drop approaches are applied on circular-shaped discs cut from steel rings with different case depths. First, a direct current potential drop (DCPD) approach is applied to measure electrical conductivity. Subsequently, an alternating current potential drop (ACPD) approach is used to measure magnetic permeability. Practical issues in measurement design and implementation are discussed. Depth profiles of electrical conductivity and magnetic permeability are reported.

Electrical insulation and conduction coating for fusion experimental devices

Energy Technology Data Exchange (ETDEWEB)

Onozuka, Masanori; Tsujimura, Seiji; Toyoda, Masahiko; Inoue, Masahiko [Mitsubishi Heavy Industries, Ltd., Yokohama (Japan); Abe, Tetsuya; Murakami, Yoshio [Japan Atomic Energy Research Inst., Naka (Japan)

1996-01-01

The development of electrical insulation and conduction coating methods that can be applied to large components of fusion experimental devices has been investigated. A thermal spraying method is used to coat the insulation or conduction materials on the structural components because of its applicability for large surfaces. The insulation material chosen was Al{sub 2}O{sub 3}, while Cr{sub 3}C{sub 2}-NiCr and WC-NiCr were chosen as conduction materials. These materials were coated on stainless steel substrates to examine the basic characteristics of the coated layers, such as their adhesive strength to the substrate, thermal shock resistance, electrical resistance, dielectric breakdown voltage, and thermal conductivity. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed adequate frictional properties. The spraying method was tested on a 100- x 1000-mm surface and found to be applicable for large surfaces of experimental fusion devices. 9 refs., 6 figs., 15 tabs.

Doping dependence of electrical and thermal conductivity of nanoscale polyaniline thin films

Energy Technology Data Exchange (ETDEWEB)

Jin Jiezhu; Wang Qing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Haque, M A [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

2010-05-26

We performed simultaneous characterization of electrical and thermal conductivity of 55 nm thick polyaniline (PANI) thin films doped with different levels of camphor sulfonic acids (CSAs). The effect of the doping level is more pronounced on electrical conductivity than on thermal conductivity of PANIs, thereby greatly affecting their ratio that determines the thermoelectric efficiency. At the 60% (the molar ratio of CSA to phenyl-N repeat unit of PANI) doping level, PANI exhibited the maximum electrical and thermal conductivity due to the formation of mostly delocalized structures. Whereas polarons are the charge carriers responsible for the electrical conduction, phonons are believed to play a dominant role in the heat conduction in nanoscale doped PANI thin films.

Total body and regional bone mineral content in hemodialysis patients

International Nuclear Information System (INIS)

Hagiwara, Satoshi; Aratani, Hideyui; Miki, Takami; Nishizawa, Yoshiki; Okamura, Terue; Koizumi, Yoshiko; Ochi, Hironobu; Morii, Hirotoshi

1994-01-01

Bone mineral content (BMC) in the total body and lumbar spine was evaluated in 126 hemodialysis patients (60 males, 66 females) by dual photon absorptiometry with the Norland DBD 2600. Measurements of: 1) total body BMC divided by lean body mass (BMC TB /LBM), 2) bone mineral density (BMD) of total body, 3) BMD of four regional sections (head, trunk, pelvis, and legs), and 4) BMD of lumbar spine, generally showed a significant decrease in the hemodialysis patients compared to the reference population. However, arm BMD did not show a significant difference between patients and control populations. The z-score of BMC TB /LBM declined significantly throughout the duration of hemodialysis, although that of the lumbar spine BMD did not. It should be noted that the degree of decrease in BMC was more prominent in the total body measurement than in the lumbar spine measurement. There was preferential osteopenia of the total body in the hemodialysis patients. Although the lumbar spine BMD showed a lower value than the control population, the lumbar spine is not the recommended region to monitor the BMD change in hemodialysis patients. (author)

Exchange of transverse plasmons and electrical conductivity of neutron star cores

International Nuclear Information System (INIS)

Shternin, P. S.

2008-01-01

We study the electrical conductivity in magnetized neutron star cores produced by collisions between charged particles. We take into account the ordinary exchange of longitudinal plasmons and the exchange of transverse plasmons in collisions between particles. The exchange of transverse plasmons is important for collisions between relativistic particles, but it has been disregarded previously when calculating the electrical conductivity. We show that taking this exchange into account changes the electrical conductivity, including its temperature dependence (thus, for example, the temperature dependence of the electrical resistivity along the magnetic field in the low-temperature limit takes the form R parallel ∝ T 5/3 instead of the standard dependence R parallel ∝ T 2 for degenerate Fermi systems). We briefly describe the effect of possible neutron and proton superfluidity in neutron star cores on the electrical conductivity and discuss various scenarios for the evolution of neutron star magnetic fields

Changes in body chemical composition with age measured by total-body neutron activation

International Nuclear Information System (INIS)

Cohn, S.H.; Vaswani, A.; Zanzi, I.; Aloia, J.F.; Roginsky, M.S.; Ellis, K.J.

1976-01-01

Total-body levels of calcium and phosphorus (reflecting skeletal mass) and total-body levels of potassium (reflecting muscle mass) were measured by neutron activation analysis in 39 men and 40 women ages 30 to 90 yr. In order to intercompare the total body calcium (TBCa) values in a heterogeneous population, such as this, it was necessary to normalize the data for skeletal size. The normalization consisted of dividing the absolute calcium level by the predicted calcium level for each individual matched to a set of critical parameters. The parameter used in the computation of normal values were age, sex, muscle mass, i.e., total body potassium (TBK) and height. For the calcium data of the women, it was necessary to add an age correction factor after the age of 55 yr. The calcium ratio (mean ratio of the predicted to measured TBCa) in men was 1.000 +- 7.8 percent and in women 0.996 +- 7.1 percent. The TBCa of normal males and females can thus be predicted to +-13 percent (at the 90 percent confidence level). An exception to this was found in males (70 to 90 yr) who exhibited a mean calcium ratio greater than 1.13

Quality control of dosimetry in total body irradiation

International Nuclear Information System (INIS)

Kallinger, W.

1986-11-01

An on-line dose measurement system for the quality control of the treatment of leukemia by means of total body irradiation with Co-60 gamma radiation is introduced. An ionization chamber and 5 diodes arranged on the surface of the patient incorporated with a microprocessor provides useful information and data necessary for the treatment. Following the concerted treatment procedure employing this system, the treatment of leukemia by means of total body irradiation is expected to be improved

Electrically Conductive Epoxy Adhesives

Directory of Open Access Journals (Sweden)

Lan Bai

2011-02-01

Full Text Available Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. The effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured adhesive matrix viscosity on the electrical conduction behavior of epoxy-based adhesives are presented in this work. For this purpose, epoxy-based adhesives were prepared using conductive fillers of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 μm in diameter, and 160 or 260 μm in length. HCl and H3PO4 acid solutions were used to etch and remove the surface oxide layers from the fillers. The plane resistance of filled adhesive films was measured using the four-point method. In all cases of conductive filler addition, the planar resistivity levels for the composite adhesive films increased when the film thickness was reduced. The shape of resistivity-thickness curves was negative exponential decaying type and was modeled using a mathematical relation. The relationships between the conductive film resistivities and the filler volume fractions were also derived mathematically based on the experimental data. Thus, the effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity could be included empirically by using these mathematical relations based on the experimental data. By utilizing the relations we proposed to model thickness-dependent and volume fraction-dependent conduction behaviors separately, we were able to describe the combined and coupled volume fraction-film thickness relationship mathematically based on our experimental data.

Highest recorded electrical conductivity and microstructure in polypropylene-carbon nanotubes composites and the effect of carbon nanofibers addition

Science.gov (United States)

Ramírez-Herrera, C. A.; Pérez-González, J.; Solorza-Feria, O.; Romero-Partida, N.; Flores-Vela, A.; Cabañas-Moreno, J. G.

2018-04-01

In the last decade, numerous investigations have been devoted to the preparation of polypropylene-multiwalled carbon nanotubes (PP/MWCNT) nanocomposites having enhanced properties, and in particular, high electrical conductivities (> 1 S cm-1). The present work establishes that the highest electrical conductivity in PP/MWCNT nanocomposites is limited by the amount of nanofiller content which can be incorporated in the polymer matrix, namely, about 20 wt%. This concentration of MWCNT in PP leads to a maximum electrical conductivity slightly lower than 8 S cm-1, but only by assuring an adequate combination of dispersion and spatial distribution of the carbon nanotubes. The realization of such an optimal microstructure depends on the characteristics of the production process of the PP/MWCNT nanocomposites; in our experiments, involving composite fabrication by melt mixing and hot pressing, a second re-processing cycle is shown to increase the electrical conductivity values by up to two orders of magnitude, depending on the MWCNT content of the nanocomposite. A modest increase of the highest electrical conductivity obtained in nanocomposites with 21.5 wt% MWCNT content has been produced by the combined use of carbon nanofibers (CNF) and MWCNT, so that the total nanofiller content was increased to 30 wt% in the nanocomposite with PP—15 wt% MWCNT—15 wt%CNF.

Solvothermal synthesis and electrical conductivity model for the zinc oxide-insulated oil nanofluid

International Nuclear Information System (INIS)

Shen, L.P.; Wang, H.; Dong, M.; Ma, Z.C.; Wang, H.B.

2012-01-01

A new kind of nanofluid, ZnO-insulated oil nanofluid was prepared from ZnO nanoparticles synthesized by solvothermal method. Electrical property measurement shows that the electrical conductivity increases by 973 times after adding 0.75% volumetric fraction of ZnO nanoparticles into the insulated oil. A linear dependence of the electrical conductivity on the volumetric fraction has been observed, while the temperature dependence of the electrical conductivity reveals a nonlinear relationship. An electrical conductivity model is established for the nanofluid by considering both the Brownian motion and electrophoresis of the ZnO nanoparticles. -- Highlights: ► Stable ZnO-insulated oil nanofluid was successfully prepared. ► The electrical conductivity of the ZnO nanofluid is investigated. ► A new model is established to explain the electrical properties of the nanofluid.

Myeloproliferative disorders in patients with rheumatoid arthritis treated with total body irradiation

International Nuclear Information System (INIS)

Urowitz, M.B.; Rider, W.D.

1985-01-01

Four patients with refractory rheumatoid arthritis were treated with total body irradiation administered in two sittings, 300 to 400 rads to each half of the body. All four patients had taken antimetabolites prior to receiving total body irradiation, and two continued to use them after total body irradiation. Two patients had taken alkylating agents before, and one had used them after total body irradiation. All patients showed clinical improvement. However, in two patients myeloproliferative disorders developed: a myelodysplastic preleukemia at 40 months after total body irradiation in one and acute myelogenous leukemia at 25 months in the other. Total body irradiation differs from total nodal irradiation in the total dose of irradiation (300 to 400 rads versus 2,000 to 3,000), and in the duration of the therapy (two sittings versus treatment over several weeks to months). Furthermore, the patients in the total body irradiation study frequently used cytotoxic drugs before and/or after irradiation, whereas in one total nodal irradiation study, azathioprine (2 mg/kg per day or less) was permitted, but no other cytotoxic agents were allowed. Rheumatologists may therefore face a binding decision when deciding to treat a patient with rheumatoid arthritis with either a cytotoxic drug or irradiation

The electrical conductivity of CuCrZr alloy after SPD processing

International Nuclear Information System (INIS)

Lipińska, M; Bazarnik, P; Lewandowska, M

2014-01-01

CuCrZr alloys exhibit very good relation between mechanical properties and electrical conductivity. However, for its use in some advanced applications improvement of mechanical strength while preserving high electrical conducting is required. Therefore, in this work a CuCrZr alloy was subjected to a series of thermo-mechanical treatments, including solution annealing and water quenching, SPD processing (using hydrostatic extrusion and ECAP) as well as aging in order to improve mechanical strength. The influence of these processing procedures on microstructure features and mechanical properties was determined by TEM observation and microhardness measurements, respectively. Electrical conductivity of the samples was measured by four-points method. The results have shown that it is possible to improve mechanical strength while preserving good electrical conductivity by a proper combination of SPD processing and heat treatment

Total body irradiation with a reconditioned cobalt teletherapy unit.

Science.gov (United States)

Evans, Michael D C; Larouche, Renée-Xavière; Olivares, Marina; Léger, Pierre; Larkin, Joe; Freeman, Carolyn R; Podgorsak, Ervin B

2006-01-01

While the current trend in radiotherapy is to replace cobalt teletherapy units with more versatile and technologically advanced linear accelerators, there remain some useful applications for older cobalt units. The expansion of our radiotherapy department involved the decommissioning of an isocentric cobalt teletherapy unit and the replacement of a column-mounted 4-MV LINAC that has been used for total body irradiation (TBI). To continue offering TBI treatments, we converted the decommissioned cobalt unit into a dedicated fixed-field total body irradiator and installed it in an existing medium-energy LINAC bunker. This article describes the logistical and dosimetric aspects of bringing a reconditioned cobalt teletherapy unit into clinical service as a total body irradiator.

Maximum on the electrical conductivity polytherm of molten TeCl{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Salyulev, Alexander B.; Potapov, Alexei M. [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry

2017-09-01

The electrical conductivity of molten TeCl{sub 4} was measured up to 761 K, i.e. 106 degrees above the normal boiling point of the salt. For the first time it was found that TeCl{sub 4} electrical conductivity polytherm has a maximum. It was recorded at 705 K (Κ{sub max}=0.245 Sm/cm), whereupon the conductivity decreases as the temperature rises. The activation energy of electrical conductivity was calculated.

Electrical and mechanical properties of asphalt concrete containing conductive fibers and fillers

NARCIS (Netherlands)

Wang, H.; Yang, Jun; Liao, Hui; Chen, Xianhua

2016-01-01

Electrically conductive asphalt concrete has the potential to satisfy multifunctional applications. Designing such asphalt concrete needs to balance the electrical and mechanical performance of asphalt concrete. The objective of this study is to design electrically conductive asphalt concrete

Numerical estimation of the effective electrical conductivity in carbon paper diffusion media

International Nuclear Information System (INIS)

Zamel, Nada; Li, Xianguo; Shen, Jun

2012-01-01

Highlights: ► Anisotropic effective electrical conductivity of the GDL is estimated numerically. ► The electrical conductivity is a key component in understanding the structure of the GDL. ► Expressions for evaluating the electrical conductivity were proposed. ► The tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively. - Abstract: The transport of electrons through the gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells has a significant impact on the optimal design and operation of PEM fuel cells and is directly affected by the anisotropic nature of the carbon paper material. In this study, a three-dimensional reconstruction of the GDL is used to numerically estimate the directional dependent effective electrical conductivity of the layer for various porosity values. The distribution of the fibers in the through-plane direction results in high electrical resistivity; hence, decreasing the overall effective electrical conductivity in this direction. This finding is in agreement with measured experimental data. Further, using the numerical results of this study, two mathematical expressions were proposed for the calculation of the effective electrical conductivity of the carbon paper GDL. Finally, the tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively.

Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges.

Science.gov (United States)

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

2016-05-01

Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10(-3) S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10(-1) S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.

Adaptation of electrical conductivity test for Moringa oleifera seeds

Directory of Open Access Journals (Sweden)

Maria Luiza de Souza Medeiros

2017-09-01

Full Text Available This study aimed to adapt and test the efficiency of electrical conductivity methodology test in quality evaluation of Moringa oleifera Lam seeds. For physiological characterization four seed sets were evaluated by tests of germination, seedlings emergency, speed of emergency index, emergency first count, seedlings length and dry mass and cold test. The electrical conductivity test was carried out at 25 °C for 4, 8, 12, 16 and 24 h of immersion in 75 or 125 mL of distilled water using 25 or 50 seeds. A completely randomized design was used. The best results were obtained when using 50 seeds immersed in 75 mL or 125 mL of distilled water for 4 h. The electrical conductivity test adapted to moringa seeds was efficient in ranking sets of different vigor levels. The test may be efficiently used for physiological quality evaluation of moringa seeds.

Enhancement in electrical conductivity of Li 2 O

Indian Academy of Sciences (India)

The study of electrical conductivity of 30Li2O : (70 – ) B2O3 : V2O5 glass samples has been carried out. The results have been explained by dividing the temperature range into two regions. In region I, conductivity shows Arrhenius behaviour for all the samples. The conductivity increases with addition of V2O5.

Implantation of total body irradiation in radiotherapy

International Nuclear Information System (INIS)

Habitzreuter, Angela Beatriz

2010-01-01

Before implementing a treatment technique, the characteristics of the beam under irradiation conditions must be well acknowledged and studied. Each one of the parameters used to calculate the dose has to be measured and validated before its utilization in clinical practice. This is particularly necessary when dealing with special techniques. In this work, all necessary parameters and measurements are described for the total body irradiation implementation in facilities designed for conventional treatments that make use of unconventional geometries to generate desired enlarged field sizes. Furthermore, this work presents commissioning data of this modality at Hospital das Clinicas of Sao Paulo using comparison of three detectors types for measurements of entrance dose during total body irradiation treatment. (author)

Electrically conductive carbon fibre-reinforced composite for aircraft lightning strike protection

Science.gov (United States)

Katunin, Andrzej; Krukiewicz, Katarzyna; Turczyn, Roman; Sul, Przemysław; Bilewicz, Marcin

2017-05-01

Aircraft elements, especially elements of exterior fuselage, are subjected to damage caused by lightning strikes. Due to the fact that these elements are manufactured from polymeric composites in modern aircraft, and thus, they cannot conduct electrical charges, the lightning strikes cause burnouts in composite structures. Therefore, the effective lightning strike protection for such structures is highly desired. The solution presented in this paper is based on application of organic conductive fillers in the form of intrinsically conducting polymers and carbon fabric in order to ensure electrical conductivity of whole composite and simultaneously retain superior mechanical properties. The presented studies cover synthesis and manufacturing of the electrically conductive composite as well as its characterization with respect to mechanical and electrical properties. The performed studies indicate that the proposed material can be potentially considered as a constructional material for aircraft industry, which characterizes by good operational properties and low cost of manufacturing with respect to current lightning strike protection materials solutions.

Nature of Dielectric Properties, Electric Modulus and AC Electrical Conductivity of Nanocrystalline ZnIn2Se4 Thin Films

Science.gov (United States)

El-Nahass, M. M.; Attia, A. A.; Ali, H. A. M.; Salem, G. F.; Ismail, M. I.

2018-02-01

The structural characteristics of thermally deposited ZnIn2Se4 thin films were indexed utilizing x-ray diffraction as well as scanning electron microscopy techniques. Dielectric properties, electric modulus and AC electrical conductivity of ZnIn2Se4 thin films were examined in the frequency range from 42 Hz to 106 Hz. The capacitance, conductance and impedance were measured at different temperatures. The dielectric constant and dielectric loss decrease with an increase in frequency. The maximum barrier height was determined from the analysis of the dielectric loss depending on the Giuntini model. The real part of the electric modulus revealed a constant maximum value at higher frequencies and the imaginary part of the electric modulus was characterized by the appearance of dielectric relaxation peaks. The AC electrical conductivity obeyed the Jonscher universal power law. Correlated barrier hopping model was the appropriate mechanism for AC conduction in ZnIn2Se4 thin films. Estimation of the density of states at the Fermi level and activation energy, for AC conduction, was carried out based on the temperature dependence of AC electrical conductivity.

Improvement of Thermal and Electrical Conductivity of Epoxy/boron Nitride/silver Nanoparticle Composite

Energy Technology Data Exchange (ETDEWEB)

Kim, Seungyong; Lim, Soonho [Korea Institute of Science and Technology, Wanju (Korea, Republic of)

2017-06-15

In this study, we investigated the effect of BN (boron nitride) on the thermal and the electrical conductivity of composites. In case of epoxy/BN composites, the thermal conductivity was increased as the BN contents were increased. Epoxy/AgNP (Ag nanoparticle) nanocomposites exhibited a slight change of thermal conductivity and showed a electrical percolation threshold at 20 vol% of Ag nanoparticles. At the fixed Ag nanoparticle content below the electrical percolation threshold, increasing the amount of BN enhanced the electrical conductivity as well as thermal conductivity for the epoxy/AgNP/BN composites.

Experimental study of electric conductivity, density and viscosity of Wood's alloy

International Nuclear Information System (INIS)

Kazandzhan, B.I.; Matveev, V.M.; Savich, T.B.; Umarov, A.M.

1989-01-01

Electric conductivity, density and kinematic viscosity of commercially pure Wood's alloy are obtained in a wide temperature range. Electric conductivity and density are investigated from the room temperature to 1000 K. Measurements of kinematic viscosity are carried out from 372 to 1000 K by means of torsional vibrations method using informatiom computer system permitting to automate data acquisition and processing and to increase the measurement accuracy. On the basis of analysis the character of electric conductivity and kinematic viscosity polyterms Wood's alloy liquidus and solidus temperatures are estimated

High temperature heat capacities and electrical conductivities of boron carbides

International Nuclear Information System (INIS)

Matsui, Tsuneo; Arita, Yuri; Naito, Keiji; Imai, Hisashi

1991-01-01

The heat capacities and the electrical conductivities of B x C(x=3, 4, 5) were measured by means of direct heating pulse calorimetry in the temperature range from 300 to 1500 K. The heat capacities of B x C increased with increasing x value. This increase in the heat capacity is probably related to the change of the lattice vibration mode originated from the reduction of the stiffness of the intericosahedral chain accompanied with a change from C-B-C to C-B-B chains. A linear relationship between the logarithm of σT (σ is the electrical conductivity and T is the absolute temperature) of B x C and the reciprocal temperature was observed, indicating the presence of small polaron hopping as the predominant conduction mechanism. The electrical conductivity of B x C also increased with increasing x value (from 4 to 5) due to an increase of the polaron hopping of holes between carbon atoms at geometrically nonequivalent sites, since these nonequivalent sites of carbon atoms were considered to increase in either B 11 C icosahedra or in icosahedral chains with increasing x. The electrical conductivity of B 3 C was higher than that of B 4 C, which is probably due to the precipitation of high-conducting carbon. The thermal conductivity and the thermodynamic quantities of B 4 C were also determined precisely from the heat capacity value. (orig.)

Electrical conductivity of chromate conversion coating on electrodeposited zinc

International Nuclear Information System (INIS)

Tencer, Michal

2006-01-01

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

Direct numerical simulation of MHD flow with electrically conducting wall

International Nuclear Information System (INIS)

Satake, S.; Kunugi, T.; Naito, N.; Sagara, A.

2006-01-01

The 2D vortex problem and 3D turbulent channel flow are treated numerically to assess the effect of electrically conducting walls on turbulent MHD flow. As a first approximation, the twin vortex pair is considered as a model of a turbulent eddy near the wall. As the eddy approaches and collides with the wall, a high value electrical potential is induced inside the wall. The Lorentz force, associated with the potential distribution, reduces the velocity gradient in the near-wall region. When considering a fully developed turbulent channel flow, a high electrical conductivity wall was chosen to emphasize the effect of electromagnetic coupling between the wall and the flow. The analysis was performed using DNS. The results are compared with a non-MHD flow and MHD flow in the insulated channel. The mean velocity within the logarithmic region in the case of the electrically conducting wall is slightly higher than that in the non-conducting wall case. Thus, the drag is smaller compared to that in the non-conducting wall case due to a reduction of the Reynolds stress in the near wall region through the Lorentz force. This mechanism is explained via reduction of the production term in the Reynolds shear stress budget

The electrical conductivity of sodium polysulfide melts

Energy Technology Data Exchange (ETDEWEB)

Meihui Wang.

1992-06-01

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

Measuring oxygen surface exchange kinetics on mixed-conducting composites by electrical conductivity relaxation

NARCIS (Netherlands)

Hu, Bobing; Wang, Yunlong; Zhu, Zhuoying; Xia, Changrong; Bouwmeester, Henricus J.M.

2015-01-01

The oxygen release kinetics of mixed-conducting Sr2Fe1.5Mo0.5O6 d–Sm0.2Ce0.8O2 d (SFM–SDC) dualphase composites has been investigated, at 750 C, as a function of the SDC phase volume fraction using electrical conductivity relaxation (ECR) under reducing atmospheres, extending our previous work on

Analysis of the electrical conduction in CdHgTe crystals

International Nuclear Information System (INIS)

Dziuba, Z.

1987-01-01

The electrical conduction versus magnetic field in p-like CdHgTe samples at 77 K is investigated by analysing the conductivity tensor components. The electrical conduction is mainly due to electrons in the conduction band and low-mobility carriers in an impurity band. In the investigated samples Cd/sub x/Hg/sub 1-x/Te with the composition x approximately 0.17 the concentration of electrons in the conduction band is higher than the intrinsic one and in samples with the composition close to HgTe the concentration of electrons in the conduction band is equal to or lower than the intrinsic one. The model of a half-filled impurity band situated close to the bottom of the conduction band is proposed to account for the concentration of electrons in the conduction band. (author)

Analytical solution of electromagnetic radiation by a vertical electric dipole inside the earth and the effect of atmospheric electrical conductivity inhomogeneity

Science.gov (United States)

Mosayebidorcheh, Taha; Hosseinibalam, Fahimeh; Hassanzadeh, Smaeyl

2017-11-01

In this paper, the effect of atmospheric electrical conductivity on the electromagnetic waves radiated by a vertical electric dipole located in the earth, near the surface of the earth, is investigated. As far as electrical conductivity is concerned, the atmosphere is divided into three areas, in which the electrical conductivity changes with altitude. The Maxwell equations in these areas are investigated as well. Using the differential transform method, the differential equation is solved in a way that atmospheric electrical conductivity is variable. Solving the problem in these areas indicates that electrical conductivity in the middle and lower areas of atmosphere may be ignored. However, in the upper areas of atmosphere, the magnitude of the magnetic field in the ionosphere at a frequency of 10 kHz at night is five times smaller when electrical conductivity is considered compared to when it is neglected.

Enhancement of electrical conductivity of ion-implanted polymer films

International Nuclear Information System (INIS)

Brock, S.

1985-01-01

The electrical conductivity of ion-implanted films of Nylon 66, Polypropylene (PP), Poly(tetrafluoroethylene) (Teflon) and mainly Poly (ethylene terephthalate) (PET) was determined by DC measurements at voltages up to 4500 V and compared with the corresponding values of pristine films. Measurements were made at 21 0 C +/- 1 0 C and 65 +/- 2% RH. The electrical conductivity of PET films implanted with F + , Ar + , or As + ions at energies of 50 keV increases by seven orders of magnitude as the fluence increases from 1 x 10 18 to 1 x 10 20 ions/m 2 . The conductivity of films implanted with As + was approximately one order greater than those implanted with Ar + , which in turn was approximately one-half order greater than those implanted with F + . The conductivity of the most conductive film ∼1 S/m) was almost 14 orders of magnitude greater than the pristine PET film. Except for the three PET samples implanted at fluences near 1 x 10 20 ions/m 2 with F + , Ar + , and As + ions, all implanted films were ohmic up to an electric field strength of 600 kV/m. The temperature dependence of the conductivity of the three PET films implanted near a fluence of 1 x 10 20 ions/m 2 was measured over the range of 80 K < T < 300 K

Software optimization for electrical conductivity imaging in polycrystalline diamond cutters

Energy Technology Data Exchange (ETDEWEB)

Bogdanov, G.; Ludwig, R. [Department of Electrical and Computer Engineering, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA 01609 (United States); Wiggins, J.; Bertagnolli, K. [US Synthetic, 1260 South 1600 West, Orem, UT 84058 (United States)

2014-02-18

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

Electrical Resistivity Survey For Conductive Soils At Gas Turbine ...

African Journals Online (AJOL)

Ten (10) vertical electrical soundings (VES) using Schlumberger configuration were carried out to delineate subsurface conductive soils for the design of earthling grid for electrical materials installation at the Gas Turbine Station, Ajaokuta, SW Nigeria. Interpretation of the resistivity data revealed three major geoelectric ...

Fluctuation-enhanced electric conductivity in electrolyte solutions.

Science.gov (United States)

Péraud, Jean-Philippe; Nonaka, Andrew J; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L

2017-10-10

We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson-Nernst-Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation-anion diffusion coefficient. Specifically, we predict a nonzero cation-anion Maxwell-Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye-Huckel-Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced "giant" velocity fluctuations and reduced fluctuations of salt concentration.

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

Science.gov (United States)

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

2011-01-01

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions. PMID:21505445

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

Science.gov (United States)

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

2011-01-01

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

Air conducted and body conducted sound produced by own voice

DEFF Research Database (Denmark)

Hansen, Mie Østergaard

1998-01-01

When we speak, sound reaches our ears both through the air, from the mouth to ear, and through our body, as vibrations. The ratio between the air borne and body conducted sound has been studied in a pilot experiment where the air borne sound was eliminated by isolating the ear with a large...... attenuation box. The ratio was found to lie between -15 dB to -7 dB, below 1 kHz, comparable with theoretical estimations. This work is part of a broader study of the occlusion effect and the results provide important input data for modelling the sound pressure change between an open and an occluded ear canal....

Properties of grafted polymer metal complexes as ion exchangers and its electrical conductivity

International Nuclear Information System (INIS)

El-Arnaouty, M.B.; Abdel Ghaffar, A.M.; Eid, M.

2011-01-01

The polyelectrolyte has been prepared as a potential proton exchanger polymer by grafting of acrylic acid/acrylamide and acrylic acid/acrylonitrile comonomer onto low density polyethylene film via gamma radiation. The influence of grafting percent on the electrical conductivity was studied. The resulting polymers were then characterized by evaluating their physico-chemical properties such as ion exchange capacity, and electrical conductivity as a function of grafting yield. The grafted films at different compositions was characterized by FTIR, TGA and SEM. The ion exchange capacity (IEC) of the grafted film at grafting % (191) and monomer concentration ratio 50:50 for (LDPE-g-AAc/AAm) was found to be more than that for (LDPE-g-AAc/AN). The electrical conductivity was found to be greatly affected by the comonomer composition where it increased as the degree of grafting increased for all grafted films. After alkaline treatment with 3% KOH, the electrical conductivity of the grafted films found to be increased. The presence of potassium as counter ion maximized the electrical conductivity of the grafted films. The electrical conductivity of Cu-membrane complexes was higher than that of both Co and Ni complexes. The electrical conductivity increases by increasing both Cu ions content and temperature

Ground electrical conductivity for medium wave activities over Nigeria

African Journals Online (AJOL)

Ground electrical properties remain a useful tool for most applications in engineering and communication, therefore, reliability and precision is highly required in their determination. Ground electrical conductivity as a function of signal frequency has been determined at Ilorin during the dry and the wet seasons. The study ...

Normal levels of total body sodium and chlorine by neutron activation analysis

International Nuclear Information System (INIS)

Kennedy, N.S.J.; Eastell, R.; Smith, M.A.; Tothill, P.

1983-01-01

In vivo neutron activation analysis was used to measure total body sodium and chlorine in 18 male and 18 female normal adults. Corrections for body size were developed. Normalisation factors were derived which enable the prediction of the normal levels of sodium and chlorine in a subject. The coefficient of variation of normalised sodium was 5.9% in men and 6.9% in women, and of normalised chlorine 9.3% in men and 5.5% in women. In the range examined (40-70 years) no significant age dependence was observed for either element. Total body sodium was correlated with total body chlorine and total body calcium. Sodium excess, defined as the amount of body sodium in excess of that associated with chlorine, also correlated well with total body calcium. In females there was a mean annual loss of sodium excess of 1.2% after the menopause, similar to the loss of calcium. (author)

The electrical conductivity of sodium polysulfide melts

Energy Technology Data Exchange (ETDEWEB)

Wang, Meihui [Univ. of California, Berkeley, CA (United States)

1992-06-01

The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na₂S₄ and Na₂S₅ were measured as a function of temperature (range: 300 to 360°C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.

Electric conductivity of molten mixtures of ternary mutual KF-KCl-ZrF4 system

International Nuclear Information System (INIS)

Darienko, S.E.; Raspopin, S.P.; Chervinskij, Yu.F.

1988-01-01

Using the relative capillary method at the frequency of 50 kHz the specific electric conductivity of molten mixtures of the KF-KCl-ZnF 4 system is measured. All the measurements were made in the atmosphere of purified argon. Temperature dependence of electric conductivity of the mixtures studied (800-1260 K) is described by the equations of exponential type with sufficient accuracy. Curves of identical specific electric conductivity of the three-component system are presented. With an increase in zirconium tetrachloride concentration in the mixtures electric conductivity of the melts decreases. On the basis of the measurement results of KF-ZrF 4 and KCl-ZrF 4 molten mixture specific electric conductivity and data on the melt density the values of molar electric conductivity at 1200 K are calculated

ZnO Coatings with Controlled Pore Size, Crystallinity and Electrical Conductivity

Directory of Open Access Journals (Sweden)

Roman SCHMACK

2016-05-01

Full Text Available Zinc oxide is a wide bandgap semiconductor with unique optical, electrical and catalytic properties. Many of its practical applications rely on the materials pore structure, crystallinity and electrical conductivity. We report a synthesis method for ZnO films with ordered mesopore structure and tuneable crystallinity and electrical conductivity. The synthesis relies on dip-coating of solutions containing micelles of an amphiphilic block copolymer and complexes of Zn2+ ions with aliphatic ligands. A subsequent calcination at 400°C removes the template and induces crystallization of the pore walls. The pore structure is controlled by the template polymer, whereas the aliphatic ligands control the crystallinity of the pore walls. Complexes with a higher thermal stability result in ZnO films with a higher content of residual carbon, smaller ZnO crystals and therefore lower electrical conductivity. The paper discusses the ability of different types of ligands to assist in the synthesis of mesoporous ZnO and relates the structure and thermal stability of the precursor complexes to the crystallinity and electrical conductivity of the zinc oxide.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.8634

Hysteresis in the relation between moisture uptake and electrical conductivity in neat epoxy

KAUST Repository

Lubineau, Gilles

2017-05-11

Monitoring changes in electrical conductivity is a simple way to assess the water uptake from environmental moisture in polymers. However, the relation between water uptake and changes in conductivity is not fully understood. We monitored changes in the electrical volume conductivity of an anhydride-cured epoxy polymer during moisture sorption-desorption experiments. Gravimetric analysis showed that the polymer exhibits a two-stage sorption behavior resulting from the competition between diffusive and reactive mechanisms. As expected, the macroscopic electrical conductivity increases with the diffusion of water. However, our most surprising observation was severe hysteresis in the relation between water uptake and electrical conductivity during the sorption and desorption experiments. This indicates that change in the electrical conductivity depends on both the water uptake and the competition between the diffusive and reactive mechanisms. We studied samples with various thicknesses to determine the relative effects of the diffusive and reactive mechanisms. This is an important observation as it means that general electrical monitoring techniques should be used cautiously when it comes to measuring the moisture content of polymer or polymer-based composite samples.

Electrical conductivity tensor of an irradiated metal

International Nuclear Information System (INIS)

Corciovei, A.; Dumitru, R.D.

1979-01-01

A method to calculate the electrical conductivity tensor of an irradiated metal is presented. The proposed method relies on the use of the Kubo formula, evaluated by a perturbation method. The one electron Hamiltonian is written as a sum of two terms: the Hamiltonian of the conduction electrons moving in a periodic lattice and the perturbation, namely, the scattering potential due to the irradiation defects of the ideal crystal. Then, the lowest order of the conductivity is determined by the lowest order of the Laplace transform of the current. An integral equation is written for this last quantity. (author)

Effect of heat treatments on the tensile and electrical properties of high-strength, high-conductivity copper alloys

Energy Technology Data Exchange (ETDEWEB)

Zinkle, S.J.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

1997-08-01

The unirradiated tensile properties of CuCrZr produced by two different vendors have been measured following different heat treatments. Room temperature electrical resistivity measurements were also performed in order to estimate the thermal conductivity of these specimens. The thermomechanical conditions studied included solution quenched, solution quenched and aged (ITER reference heat treatment), simulated slow HIP thermal cycle ({approximately}1{degrees}C/min cooling from solutionizing temperature) and simulated fast HIP thermal cycle ({approximately}100{degrees}C/min cooling from solutionizing temperature). Specimens from the last two heat treatments were tested in both the solution-cooled condition and after subsequent precipitate aging at 475{degrees}C for 2 h. Both of the simulated HIP thermal cycles caused a pronounced decreases in the strength and electrical conductivity of CuCrZr. The tensile and electrical properties were unchanged by subsequent aging in the slow HIP thermal cycles caused a pronounced decrease in the strength and electrical conductivity of CuCrZr. The tensile and electrical properties were unchanged by subsequent aging in the slow HIP thermal cycle specimens, whereas the strength and conductivity following aging in the fast HIP thermal cycle improved to {approximately}65% of the solution quenched and aged CuCrZr values. Limited tensile and electrical resistivity measurements were also made on two new heats of Hycon 3HP CuNiBe. High strength but poor uniform and total elongations were observed at 500{degrees}C on one of these new heats of CuNiBe, similar to that observed in other heats.

Effect of heat treatments on the tensile and electrical properties of high-strength, high-conductivity copper alloys

International Nuclear Information System (INIS)

Zinkle, S.J.; Eatherly, W.S.

1997-01-01

The unirradiated tensile properties of CuCrZr produced by two different vendors have been measured following different heat treatments. Room temperature electrical resistivity measurements were also performed in order to estimate the thermal conductivity of these specimens. The thermomechanical conditions studied included solution quenched, solution quenched and aged (ITER reference heat treatment), simulated slow HIP thermal cycle (∼1 degrees C/min cooling from solutionizing temperature) and simulated fast HIP thermal cycle (∼100 degrees C/min cooling from solutionizing temperature). Specimens from the last two heat treatments were tested in both the solution-cooled condition and after subsequent precipitate aging at 475 degrees C for 2 h. Both of the simulated HIP thermal cycles caused a pronounced decreases in the strength and electrical conductivity of CuCrZr. The tensile and electrical properties were unchanged by subsequent aging in the slow HIP thermal cycles caused a pronounced decrease in the strength and electrical conductivity of CuCrZr. The tensile and electrical properties were unchanged by subsequent aging in the slow HIP thermal cycle specimens, whereas the strength and conductivity following aging in the fast HIP thermal cycle improved to ∼65% of the solution quenched and aged CuCrZr values. Limited tensile and electrical resistivity measurements were also made on two new heats of Hycon 3HP CuNiBe. High strength but poor uniform and total elongations were observed at 500 degrees C on one of these new heats of CuNiBe, similar to that observed in other heats

Electrical Conductivity of CUXS Thin Film Deposited by Chemical ...

African Journals Online (AJOL)

Thin films of CuxS have successfully been deposited on glass substrates using the Chemical Bath Deposition (CBD) technique. The films were then investigated for their electrical properties. The results showed that the electrical conductivities of the CuxS films with different molarities (n) of thiourea (Tu), determined using ...

DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications

International Nuclear Information System (INIS)

Katoh, Y.; Kondo, S.; Snead, L.L.

2009-01-01

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

Thermodynamic parameters of elasticity and electrical conductivity ...

African Journals Online (AJOL)

The thermodynamic parameters (change in free energy of elasticity, DGe; change in enthalpy of elasticity, DHe; and change in entropy of elasticity, DSe) and the electrical conductivity of natural rubber composites reinforced separately with some agricultural wastes have been determined. Results show that the reinforced ...

Measuring electric conductivity in liquid metals by eddy current method

International Nuclear Information System (INIS)

Zhuravlev, S.P.; Ostrovskij, O.I.; Grigoryan, V.A.

1982-01-01

Technique permitting to apply the method of vertiginous currents for investigation of electric conductivity of metal melts in the high temperature range is presented. Interferences affecting accuracy of measurements are specified and ways of their removing are pointed out. Scheme of measuring and design of the facility are described. Results of measuring electric resistance of liquid Fe, Co, Ni obtained for the first time by this method are presented. The data obtained agree with the results of measurements conducted by the method of the rotating magnetic field. Difference in absolute values of electric resistance in parallel experiments for each metal does not exceed 4%

Facile synthesis of degradable and electrically conductive polysaccharide hydrogels.

Science.gov (United States)

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

2011-07-11

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

Development of Tailorable Electrically Conductive Thermal Control Material Systems

Science.gov (United States)

Deshpande, M. S.; Harada, Y.

1997-01-01

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

Microbial interspecies electron transfer via electric currents through conductive minerals

Science.gov (United States)

Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya

2012-01-01

In anaerobic biota, reducing equivalents (electrons) are transferred between different species of microbes [interspecies electron transfer (IET)], establishing the basis of cooperative behaviors and community functions. IET mechanisms described so far are based on diffusion of redox chemical species and/or direct contact in cell aggregates. Here, we show another possibility that IET also occurs via electric currents through natural conductive minerals. Our investigation revealed that electrically conductive magnetite nanoparticles facilitated IET from Geobacter sulfurreducens to Thiobacillus denitrificans, accomplishing acetate oxidation coupled to nitrate reduction. This two-species cooperative catabolism also occurred, albeit one order of magnitude slower, in the presence of Fe ions that worked as diffusive redox species. Semiconductive and insulating iron-oxide nanoparticles did not accelerate the cooperative catabolism. Our results suggest that microbes use conductive mineral particles as conduits of electrons, resulting in efficient IET and cooperative catabolism. Furthermore, such natural mineral conduits are considered to provide ecological advantages for users, because their investments in IET can be reduced. Given that conductive minerals are ubiquitously and abundantly present in nature, electric interactions between microbes and conductive minerals may contribute greatly to the coupling of biogeochemical reactions. PMID:22665802

Effect of Microstructure on Electrical Conductivity of Nickel-Base Superalloys

Science.gov (United States)

Nagarajan, Balasubramanian; Castagne, Sylvie; Annamalai, Swaminathan; Fan, Zheng; Chan, Wai Luen

2017-08-01

Eddy current spectroscopy is one of the promising non-destructive methods for residual stress evaluation along the depth of subsurface-treated nickel-base superalloys, but it is limited by its sensitivity to microstructure. This paper studies the influence of microstructure on the electrical conductivity of two nickel-base alloys, RR1000 and IN100. Different microstructures were attained using heat treatment cycles ranging from solution annealing to aging, with varying aging time and temperature. Eddy current conductivity was measured using conductivity probes of frequencies ranging between 1 and 5 MHz. Qualitative and quantitative characterization of the microstructure was performed using optical and scanning electron microscopes. For the heat treatment conditions between the solution annealing and the peak aging, the electrical conductivity of RR1000 increased by 6.5 pct, which is duly substantiated by the corresponding increase in hardness (12 pct) and the volume fraction of γ' precipitates (41 pct). A similar conductivity rise of 2.6 pct for IN100 is in agreement with the increased volume fraction of γ' precipitates (12.5 pct) despite an insignificant hardening between the heat treatment conditions. The observed results with RR1000 and IN100 highlight the sensitivity of electrical conductivity to the minor microstructure variations, especially the volume fraction of γ' precipitates, within the materials.

Density, dynamic viscosity, and electrical conductivity of pyridinium-based hydrophobic ionic liquids

International Nuclear Information System (INIS)

Liu, Qing-Shan; Li, Pei-Pei; Welz-Biermann, Urs; Chen, Jian; Liu, Xiao-Xia

2013-01-01

Highlights: • Targets of this research are hydrophobic series ionic liquids. • Density, dynamic viscosity and electrical conductivity were determined. • Influences of methylene to properties were discussed. • Influences of methyl group on pyridinium ring position to properties were discussed. • Relationship of ρ, η and σ were described systematically. -- Abstract: Air and water stable hydrophobic ionic liquids (ILs) were synthesized: N-propyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide [C 3 3mpy][NTf 2 ], N-hexyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide [C 6 3mpy][NTf 2 ], and N-hexyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide [C 6 4mpy][NTf 2 ]. Density, dynamic viscosity, and electrical conductivity of ILs were determined at atmospheric pressure in the temperature range of (278 to 353) K. The effects of methylene and methyl groups to density, dynamic viscosity, and electrical conductivity, respectively, were discussed. The thermal expansion coefficient, molecular volume, standard molar entropy, and lattice energy of the samples were estimated in terms of empirical and semi-empirical equations based on the density values. The temperature dependence on dynamic viscosity and electrical conductivity values of the ILs were discussed by Vogel–Fulcher–Tamman (VFT) and Arrhenius equations. The molar conductivities were calculated by density and electrical conductivity values

Fabrication of highly conductive carbon nanotube fibers for electrical application

International Nuclear Information System (INIS)

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

2015-01-01

Carbon nanotubes (CNTs) have great potential for use as electrical wires because of their outstanding electrical and mechanical properties. Here, we fabricate lightweight CNT fibers with electrical conductivity as high as that of stainless steel from macroscopic CNT films by drawing them through diamond wire-drawing dies. The entangled CNT bundles are straightened by suffering tension, which improves the alignment of the fibers. The loose fibers are squeezed by the diamond wire-drawing dies, which reduces the intertube space and contact resistance. The CNT fibers prepared by drawing have an electrical conductivity as high as 1.6 × 10 6 s m −1 . The fibers are very stable when kept in the air and under cyclic tensile test. A prototype of CNT motor is demonstrated by replacing the copper wires with the CNT fibers. (paper)

Electrical conductivities and chemical stabilities of mixed conducting pyrochlores for SOFC applications

DEFF Research Database (Denmark)

Holtappels, P.; Poulsen, F.W.; Mogensen, Mogens Bjerg

2000-01-01

Pyrochlores with praseodymium as the A-site cation and zirconium, tin, cerium and manganese cations on the B-site were prepared in air and their electrical conductivities were investigated as a function of oxygen partial pressure and temperature. Pure Pr2Zr2O7+/-delta as well as samples modified...

Computer modeling of the combined effects of perfusion, electrical conductivity, and thermal conductivity on tissue heating patterns in radiofrequency tumor ablation.

Science.gov (United States)

Ahmed, Muneeb; Liu, Zhengjun; Humphries, Stanley; Goldberg, S Nahum

2008-11-01

To use an established computer simulation model of radiofrequency (RF) ablation to characterize the combined effects of varying perfusion, and electrical and thermal conductivity on RF heating. Two-compartment computer simulation of RF heating using 2-D and 3-D finite element analysis (ETherm) was performed in three phases (n = 88 matrices, 144 data points each). In each phase, RF application was systematically modeled on a clinically relevant template of application parameters (i.e., varying tumor and surrounding tissue perfusion: 0-5 kg/m(3)-s) for internally cooled 3 cm single and 2.5 cm cluster electrodes for tumor diameters ranging from 2-5 cm, and RF application times (6-20 min). In the first phase, outer thermal conductivity was changed to reflect three common clinical scenarios: soft tissue, fat, and ascites (0.5, 0.23, and 0.7 W/m- degrees C, respectively). In the second phase, electrical conductivity was changed to reflect different tumor electrical conductivities (0.5 and 4.0 S/m, representing soft tissue and adjuvant saline injection, respectively) and background electrical conductivity representing soft tissue, lung, and kidney (0.5, 0.1, and 3.3 S/m, respectively). In the third phase, the best and worst combinations of electrical and thermal conductivity characteristics were modeled in combination. Tissue heating patterns and the time required to heat the entire tumor +/-a 5 mm margin to >50 degrees C were assessed. Increasing background tissue thermal conductivity increases the time required to achieve a 50 degrees C isotherm for all tumor sizes and electrode types, but enabled ablation of a given tumor size at higher tissue perfusions. An inner thermal conductivity equivalent to soft tissue (0.5 W/m- degrees C) surrounded by fat (0.23 W/m- degrees C) permitted the greatest degree of tumor heating in the shortest time, while soft tissue surrounded by ascites (0.7 W/m- degrees C) took longer to achieve the 50 degrees C isotherm, and complete ablation

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

KAUST Repository

Zhou, Jian; Lubineau, Gilles

2013-01-01

concentration (0.3 wt %). To tailor the electrical properties of the conductive polymer coating, we used a polar solvent ethylene glycol, and we can tune the final properties of the nanocomposite by controlling the concentrations of the elementary constituents

Differential and directional effects of perfusion on electrical and thermal conductivities in liver.

Science.gov (United States)

Podhajsky, Ronald J; Yi, Ming; Mahajan, Roop L

2009-01-01

Two different measurement probes--an electrical probe and a thermal conductivity probe--were designed, fabricated, calibrated, and used in experimental studies on a pig liver model that was designed to control perfusion rates. These probes were fabricated by photolithography and mounted in 1.5-mm diameter catheters. We measured the local impedance and thermal conductivity, respectively, of the artificially perfused liver at different flow rates and, by rotating the probes, in different directions. The results show that both the local electrical conductivity and the thermal conductivity varied location to location, that thermal conductivity increased with decreased distance to large blood vessels, and that significant directional differences exist in both electrical and thermal conductivities. Measurements at different perfusion rates demonstrated that both the local electrical and local thermal conductivities increased linearly with the square root of perfusion rate. These correlations may be of great value to many energy-based biomedical applications.

Magneto-acousto-electrical Measurement Based Electrical Conductivity Reconstruction for Tissues.

Science.gov (United States)

Zhou, Yan; Ma, Qingyu; Guo, Gepu; Tu, Juan; Zhang, Dong

2018-05-01

Based on the interaction of ultrasonic excitation and magnetoelectrical induction, magneto-acousto-electrical (MAE) technology was demonstrated to have the capability of differentiating conductivity variations along the acoustic transmission. By applying the characteristics of the MAE voltage, a simplified algorithm of MAE measurement based conductivity reconstruction was developed. With the analyses of acoustic vibration, ultrasound propagation, Hall effect, and magnetoelectrical induction, theoretical and experimental studies of MAE measurement and conductivity reconstruction were performed. The formula of MAE voltage was derived and simplified for the transducer with strong directivity. MAE voltage was simulated for a three-layer gel phantom and the conductivity distribution was reconstructed using the modified Wiener inverse filter and Hilbert transform, which was also verified by experimental measurements. The experimental results are basically consistent with the simulations, and demonstrate that the wave packets of MAE voltage are generated at tissue interfaces with the amplitudes and vibration polarities representing the values and directions of conductivity variations. With the proposed algorithm, the amplitude and polarity of conductivity gradient can be restored and the conductivity distribution can also be reconstructed accurately. The favorable results demonstrate the feasibility of accurate conductivity reconstruction with improved spatial resolution using MAE measurement for tissues with conductivity variations, especially suitable for nondispersive tissues with abrupt conductivity changes. This study demonstrates that the MAE measurement based conductivity reconstruction algorithm can be applied as a new strategy for nondestructive real-time monitoring of conductivity variations in biomedical engineering.

Evaluation of body composition and nitrogen content of renal patients on chronic dialysis as determined by total body neutron activation

International Nuclear Information System (INIS)

Cohn, S.H.; Brennan, B.L.; Yasumura, S.; Vartsky, D.; Vaswani, A.N.; Ellis, K.J.

1983-01-01

Total body protein (nitrogen), body cell mass (potassium), fat, and water were measured in 15 renal patients on maintenance hemodialysis (MHD). Total body nitrogen was measured by means of prompt γ neutron activation analysis; total body water was determined with tritium labeled water; total body potassium was measured by whole body counting. The extracellular water was determined by a technique utilizing the measurement of total body chloride and plasma chloride. When compared with corresponding values of a control group of the same age, sex, and height, the protein content, body cell mass, and total body fat of the MHD patients were within the normal range. The only significant change was an increase in the extracellular water/body cell mass ratio in the male MHD patients compared to the control. The lack of significant difference of the nitrogen values of the MHD patients compared to matched controls suggests that dialysis minimizes any residual effects of uremic toxicity or protein-calorie malnutrition. These findings further suggest that there is a need to reevaluate the traditional anthropometric and biochemical standards of nutritional status for MHD patients. It was concluded that it is particularly important to measure protein stores of MHD patients with low protein intake to ascertain nutritional status. Finally, in vivo measurement of total body nitrogen and potassium for determination of body composition provides a simple, direct, and accurate assessment of the nutritional status of MHD patients

On the importance of body posture and skin modelling with respect to in situ electric field strengths in magnetic field exposure scenarios

Science.gov (United States)

Schmid, Gernot; Hirtl, Rene

2016-06-01

The reference levels and maximum permissible exposure values for magnetic fields that are currently used have been derived from basic restrictions under the assumption of upright standing body models in a standard posture, i.e. with arms laterally down and without contact with metallic objects. Moreover, if anatomical modelling of the body was used at all, the skin was represented as a single homogeneous tissue layer. In the present paper we addressed the possible impacts of posture and skin modelling in scenarios of exposure to a 50 Hz uniform magnetic field on the in situ electric field strength in peripheral tissues, which must be limited in order to avoid peripheral nerve stimulation. We considered different body postures including situations where body parts form large induction loops (e.g. clasped hands) with skin-to-skin and skin-to-metal contact spots and compared the results obtained with a homogeneous single-layer skin model to results obtained with a more realistic two-layer skin representation consisting of a low-conductivity stratum corneum layer on top of a combined layer for the cellular epidermis and dermis. Our results clearly indicated that postures with loops formed of body parts may lead to substantially higher maximum values of induced in situ electric field strengths than in the case of standard postures due to a highly concentrated current density and in situ electric field strength in the skin-to-skin and skin-to-metal contact regions. With a homogeneous single-layer skin, as is used for even the most recent anatomical body models in exposure assessment, the in situ electric field strength may exceed the basic restrictions in such situations, even when the reference levels and maximum permissible exposure values are not exceeded. However, when using the more realistic two-layer skin model the obtained in situ electric field strengths were substantially lower and no violations of the basic restrictions occurred, which can be explained by the

Experimental and numerical investigation of the effective electrical conductivity of nitrogen-doped graphene nanofluids

Energy Technology Data Exchange (ETDEWEB)

Mehrali, Mohammad, E-mail: mohamad.mehrali@siswa.um.edu.my [University of Malaya, Department of Mechanical Engineering and Advanced Material Research Centre (Malaysia); Sadeghinezhad, Emad, E-mail: esn802001@yahoo.com [University of Malaya, Department of Mechanical Engineering (Malaysia); Rashidi, Mohammad Mehdi [Tongji University, Shanghai Automotive Wind Tunnel Center (China); Akhiani, Amir Reza; Tahan Latibari, Sara; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis [University of Malaya, Department of Mechanical Engineering and Advanced Material Research Centre (Malaysia)

2015-06-15

Electrical conductivity is an important property for technological applications of nanofluids that have not been widely investigated, and few studies have been concerned about the electrical conductivity. In this study, nitrogen-doped graphene (NDG) nanofluids were prepared using the two-step method in an aqueous solution of 0.025 wt% Triton X-100 as a surfactant at several concentrations (0.01, 0.02, 0.04, 0.06 wt%). The electrical conductivity of the aqueous NDG nanofluids showed a linear dependence on the concentration and increased up to 1814.96 % for a loading of 0.06 wt% NDG nanosheet. From the experimental data, empirical models were developed to express the electrical conductivity as functions of temperature and concentration. It was observed that increasing the temperature has much greater effect on electrical conductivity enhancement than increasing the NDG nanosheet loading. Additionally, by considering the electrophoresis of the NDG nanosheets, a straightforward electrical conductivity model is established to modulate and understand the experimental results.

Experimental and numerical investigation of the effective electrical conductivity of nitrogen-doped graphene nanofluids

Science.gov (United States)

Mehrali, Mohammad; Sadeghinezhad, Emad; Rashidi, Mohammad Mehdi; Akhiani, Amir Reza; Tahan Latibari, Sara; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis

2015-06-01

Electrical conductivity is an important property for technological applications of nanofluids that have not been widely investigated, and few studies have been concerned about the electrical conductivity. In this study, nitrogen-doped graphene (NDG) nanofluids were prepared using the two-step method in an aqueous solution of 0.025 wt% Triton X-100 as a surfactant at several concentrations (0.01, 0.02, 0.04, 0.06 wt%). The electrical conductivity of the aqueous NDG nanofluids showed a linear dependence on the concentration and increased up to 1814.96 % for a loading of 0.06 wt% NDG nanosheet. From the experimental data, empirical models were developed to express the electrical conductivity as functions of temperature and concentration. It was observed that increasing the temperature has much greater effect on electrical conductivity enhancement than increasing the NDG nanosheet loading. Additionally, by considering the electrophoresis of the NDG nanosheets, a straightforward electrical conductivity model is established to modulate and understand the experimental results.

Experimental and numerical investigation of the effective electrical conductivity of nitrogen-doped graphene nanofluids

International Nuclear Information System (INIS)

Mehrali, Mohammad; Sadeghinezhad, Emad; Rashidi, Mohammad Mehdi; Akhiani, Amir Reza; Tahan Latibari, Sara; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis

2015-01-01

Electrical conductivity is an important property for technological applications of nanofluids that have not been widely investigated, and few studies have been concerned about the electrical conductivity. In this study, nitrogen-doped graphene (NDG) nanofluids were prepared using the two-step method in an aqueous solution of 0.025 wt% Triton X-100 as a surfactant at several concentrations (0.01, 0.02, 0.04, 0.06 wt%). The electrical conductivity of the aqueous NDG nanofluids showed a linear dependence on the concentration and increased up to 1814.96 % for a loading of 0.06 wt% NDG nanosheet. From the experimental data, empirical models were developed to express the electrical conductivity as functions of temperature and concentration. It was observed that increasing the temperature has much greater effect on electrical conductivity enhancement than increasing the NDG nanosheet loading. Additionally, by considering the electrophoresis of the NDG nanosheets, a straightforward electrical conductivity model is established to modulate and understand the experimental results

Thermal and electrical conductivities of high purity tantalum

International Nuclear Information System (INIS)

Archer, S.L.

1978-01-01

The electrical resistivity and thermal conductivity of three high purity tantalum samples have been measured as functions of temperature over a temperature range of 5K to 65K. Sample purities ranged up to a resistivity ratio of 1714. The highest purity sample had a residual resistivity of .76 x 10 -10 OMEGA-m. The intrinsic resistivity varied as T 3 . 9 from 10K to 31K. The thermal conductivity of the purest sample had a maximum of 840 W/mK at 9.8K. The intrinsic thermal resistivity varied as T 2 . 4 from 10K to 35K. At low temperatures electrons were scattered primarily by impurities and by phonons with both interband and intraband transitions observed. The electrical and thermal resistivity is departed from Matthiessen's rule at low temperatures

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

International Nuclear Information System (INIS)

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

2013-01-01

Highlights: •The electrical conductivity of PPLP in LN 2 was successfully measured. •Based on the measured value of PPLP, DC field analysis was performed. •The electric field distribution was altered according to the DC applying stages. •The maximum electric field was observed during polarity reversal situation. •DC field analysis is important to determine the optimum design of DC HTS devices. -- Abstract: High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN 2 ). Electrical conductivity of PPLP in LN 2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN 2 were presented in this paper. Based on the experimental works, DC electric field distribution of

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

Science.gov (United States)

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

2014-11-12

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

Electrical conductivity measurement and thermogravimetric study of chromium-doped uranium dioxide

International Nuclear Information System (INIS)

Matsui, Tsuneo; Naito, Keiji

1986-01-01

The electrical conductivity and nonstoichiometric composition of (Usub(1-y)Crsub(y))Osub(2+x) (y=0.001 and 0.05) were measured in the range 1173 -17 2 ) -2 Pa by the four inserted wires method and thermogravimetry, respectively. The electrical conductivities of (Usub(1-y)Crsub(y))Osub(2+x) (y=0.01 and 0.05) were about one-order lower than that of UOsub(2+x), probably due to the presence of the chromium ion as an electron donor. The activation energies of (Usub(0.99)Crsub(0.01))Osub(2+x) and (Usub(0.95)Crsub(0.05))Osub(2+x) for the extrinsic conduction in the low oxygen partial pressure region were calculated to be 24.7+-1.3 and 25.9+-1.0 kJ.mol -1 , respectively from the Arrhenius plots of the electrical conductivities. These small values of the activation energy of (Usub(1-y)Crsub(y))Osub(2+x) may suggest the presence of the hopping mechanism for hole conduction, similarly to the case of UOsub(2+x). From the oxygen partial pressure dependences of both the electrical conductivity and the deviation x in (Usub(1-y)Crsub(y))Osub(2+x), the defect structure was discussed with the complex defect model consisting of oxygen vacancies and two kinds of interstitial oxygens. (orig.)

Leaching of Conductive Species: Implications to Measurements of Electrical Resistivity.

Science.gov (United States)

Spragg, R; Jones, S; Bu, Y; Lu, Y; Bentz, D; Snyder, K; Weiss, J

2017-05-01

Electrical tests have been used to characterize the microstructure of porous materials, the measured electrical response being determined by the contribution of the microstructure (porosity and tortuosity) and the electrical properties of the solution (conductivity of the pore solution) inside the pores of the material. This study has shown how differences in concentration between the pore solution (i.e., the solution in the pores) and the storage solution surrounding the test specimen leads to significant transport (leaching) of the conductive ionic species between the pore solution and the storage solution. Leaching influences the resistivity of the pore solution, thereby influencing electrical measurements on the bulk material from either a surface or uniaxial bulk resistance test. This paper has three main conclusions: 1.) Leaching of conductive species does occur with concentration gradients and that a diffusion based approach can be used to estimate the time scale associated with this change. 2.) Leaching of ions in the pore solution can influence resistivity measurements, and the ratio of surface to uniaxial resistivity can be used as a method to assess the presence of leaching and 3.) An estimation of the magnitude of leaching for standardized tests of cementitious materials.

Enhanced electrical conductivity in Xe ion irradiated CNT based transparent conducting electrode on PET substrate

Science.gov (United States)

Surbhi; Sharma, Vikas; Singh, Satyavir; Garg, Priyanka; Asokan, K.; Sachdev, Kanupriya

2018-02-01

An investigation of MWCNT-based hybrid electrode films with improved electrical conductivity after Xe ion irradiation is reported. A multilayer hybrid structure of Ag-MWCNT layer embedded in between two ZnO layers was fabricated and evaluated, pre and post 100 keV Xe ion irradiation, for their performance as Transparent Conducting Electrode in terms of their optical and electrical properties. X-ray diffraction pattern exhibits highly c-axis oriented ZnO films with a small variation in lattice parameters with an increase in ion fluence. There is no significant change in the surface roughness of these films. Raman spectra were used to confirm the presence of CNT. The pristine multilayer films exhibit an average transmittance of ˜70% in the entire visible region and the transmittance increases with Xe ion fluence. A significant enhancement in electrical conductivity post-Xe ion irradiation viz from 1.14 × 10-7 Ω-1 cm-1 (pristine) to 7.04 × 103 Ω-1 cm-1 is seen which is due to the high connectivity in the top layer with Ag-CNT hybrid layer facilitating the smooth transfer of electrons.

A simple calibration of a whole-body counter for the measurement of total body potassium in humans

International Nuclear Information System (INIS)

Abdel-Wahab, M.S.; El-Fiki, S.A.; El-Enany, N.; Youssef, S.K.; Aly, A.M.; Abbas, M.T.

1992-01-01

A simple calibration procedure for the Inshas whole body counter for evaluating total body potassium has been adopted. More than 120 Egyptian employees in the Nuclear Research Center (N.R.C.) were studied for their total body potassium (TBK). The potassium values were found to have an average of 2.85±0.57 g K kg -1 body weight for males and 2.62±0.52 g K kg -1 for females, which are higher than the recommended value given for reference man by ICRP. The TBK varied directly with body build index and is slightly sex dependent (Author)

Solving hyperbolic heat conduction using electrical simulation

International Nuclear Information System (INIS)

Gheitaghy, A. M.; Talaee, M. R.

2013-01-01

In the present study, the electrical network simulation method is proposed to solve the hyperbolic and parabolic heat conduction problem considering Cattaneo-Vernoute (C.V) constitutive relation. Using this new proposed numerical model and the electrical circuit simulation program HSPICE, transient temperature and heat flux profiles at slab can be obtained easily and quickly. To verify the proposed method, the obtained numerical results for cases of one dimensional two-layer slab under periodic boundary temperature with perfect and imperfect thermal contact are compared with the published results. Comparisons show the proposed technique might be considered as a useful tool in the analysis of parabolic and hyperbolic thermal problems.

Method and device for electromagnetic pumping by conduction of liquid metals having low electrical conductivity

International Nuclear Information System (INIS)

Le Frere, J.P.

1976-01-01

The invention is related to a method for pumping of liquid metals having a low electrical conductivity. To lower the resistance of the conductive spire containing liquid metal to be pumped, a tape formed by a conductive metal such as copper or nickel is inserted in that spire. The tape is interrupted at the level of the air gap of the main magnetic circuit at least when the conductive spire passes through that air gap

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

Science.gov (United States)

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

Integral bounds for N-body total cross sections

International Nuclear Information System (INIS)

Osborn, T.A.; Bolle, D.

1979-01-01

We study the behavior of the total cross sections in the three- and N-body scattering problem. Working within the framework of the time-dependent two-Hilbert space scattering theory, we give a simple derivation of integral bounds for the total cross section for all processes initiated by the collision of two clusters. By combining the optical theorem with a trace identity derived by Jauch, Sinha, and Misra, we find, roughly speaking, that if the local pairwise interaction falls off faster than r -3 , then sigma/sub tot/(E) must decrease faster than E/sup -1/2/ at high energy. This conclusion is unchanged if one introduces a class of well-behaved three-body interactions

Electrically conducting nanobiocomposites using carbon nanotubes and collagen waste fibers

International Nuclear Information System (INIS)

Meiyazhagan, Ashokkumar; Thangavel, Saravanamoorthy; Hashim, Daniel P.; Ajayan, Pulickel M.; Palanisamy, Thanikaivelan

2015-01-01

Electrically conducting hybrid biocomposite films were prepared using a simple and cost-effective method by incorporating different types of carbon nanotubes (XCNTs) viz., few walled carbon nanotube (FWCNT) and boron doped carbon nanotube (BCNT) into biopolymers. Collagen extracted from animal skin wastes was blended with guar gum and XCNTs in varying proportions to form flexible and electrically conducting hybrid films. We found that the electrical conductivity of both types of hybrid films increases radically as the XCNT loading increases. BCNT incorporated hybrid films show better electrical conductivity (3.0 × 10 −1 S/cm) than their FWCNT loaded counter parts (4.8 × 10 −4 S/cm) at a dosage of 2 wt.%. On the other hand, mechanical and other physical properties such as transparency, flexibility and surface smoothness of the developed hybrid films were affected as a function of XCNT concentration. We also demonstrated that the developed hybrid films lit up a LED lamp when inserted between batteries and the brightness of the emitted light depended on the XCNT loading. These results suggest a new way to transform an industrial biowaste into innovative advanced materials for applications in fields related to biomedicine, biosensors and electronics. - Highlights: • Hybrid nanobiocomposite films prepared using collagen, guar gum and CNTs. • Examined the effect of CNT doping on the properties of hybrid biocomposite films. • Higher CNT loading improved the conductivity radically, especially for BCNT. • The ability of developed hybrid films to lit up a LED lamp was demonstrated. • The results suggest a new way to transform biowaste into advanced materials

Electric field dependence of excess electrical conductivity below transition temperature in thin superconducting lead films

Energy Technology Data Exchange (ETDEWEB)

Ashwini Kumar, P K; Duggal, V P [Delhi Univ. (India). Dept. of Physics and Astrophysics

1976-01-26

Results of measurements of the electric field dependence of the excess electrical conductivity are reported in thin superconducting lead films below the transition temperature. It is observed that the normal state sheet resistance has some effect on the nonlinearity but the theory of Yamaji still fits well to the experimental data.

Microstructural inhomogeneity of electrical conductivity in subcutaneous fat tissue.

Directory of Open Access Journals (Sweden)

Ilja L Kruglikov

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

Hopping transport and electrical conductivity in one-dimensional systems with off-diagonal disorder

International Nuclear Information System (INIS)

Ma Songshan; Xu Hui; Li Yanfeng; Song Zhaoquan

2007-01-01

In this paper, we present a model to describe hopping transport and electrical conductivity of one-dimensional systems with off-diagonal disorder, in which electrons are transported via hopping between localized states. We find that off-diagonal disorder leads to delocalization and drastically enhances the electrical conductivity of systems. The model also quantitatively explains the temperature and electrical field dependence of the conductivity in one-dimensional systems with off-diagonal disorder. In addition, we also show the dependence of the conductivity on the strength of off-diagonal disorder

Predicting permeability and electrical conductivity of sedimentary rocks from microgeometry

International Nuclear Information System (INIS)

Schlueter, E.M.; Cook, N.G.W.

1991-02-01

The determination of hydrologic parameters that characterize fluid flow through rock masses on a large scale (e.g., hydraulic conductivity, capillary pressure, and relative permeability) is crucial to activities such as the planning and control of enhanced oil recovery operations, and the design of nuclear waste repositories. Hydraulic permeability and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. The cross-sectional areas and perimeters of the individual pores are estimated from two-dimensional scanning electron micrographs of rock sections. The hydraulic and electrical conductivities of the individual pores are determined from these geometrical parameters, using Darcy's law and Ohm's law. Account is taken of the fact that the cross-sections are randomly oriented with respect to the channel axes, and for possible variation of cross-sectional area along the length of the pores. The effective medium theory from solid-state physics is then used to determine an effective average conductance of each pore. Finally, the pores are assumed to be arranged on a cubic lattice, which allows the calculation of overall macroscopic values for the permeability and the electrical conductivity. Preliminary results using Berea, Boise, Massilon and Saint-Gilles sandstones show reasonably close agreement between the predicted and measured transport properties. 12 refs., 5 figs., 1 tab

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

Science.gov (United States)

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

2013-11-01

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

Damage detection and conductivity evolution in carbon nanofiber epoxy via electrical impedance tomography

International Nuclear Information System (INIS)

Tallman, T N; Wang, K W; Gungor, S; Bakis, C E

2014-01-01

Utilizing electrically conductive nanocomposites for integrated self-sensing and health monitoring is a promising area of structural health monitoring (SHM) research wherein local changes in conductivity coincide with damage. In this research we conduct proof of concept investigations using electrical impedance tomography (EIT) for damage detection by identifying conductivity changes and by imaging conductivity evolution in a carbon nanofiber (CNF) filled epoxy composite. CNF/epoxy is examined because fibrous composites can be manufactured with a CNF/epoxy matrix thereby enabling the entire matrix to become self-sensing. We also study the mechanisms of conductivity evolution in CNF/epoxy through electrical impedance spectroscopy (EIS) testing. The results of these tests indicate that thermal expansion is responsible for conductivity evolution in a CNF/epoxy composite. (paper)

Apparatus for simultaneously measuring electrical conductivity and oxygen fugacity

Energy Technology Data Exchange (ETDEWEB)

Netherton, R.; Duba, A.

1978-01-31

Electrical conductivity studies of silicates are useful in determining temperature vs depth in the earth. Realistic laboratory measurements of conduction mechanisms require that exact determinations of oxygen fugacity (fo{sub 2}) be made in the experimental environment. An apparatus is described that monitors system fo{sub 2} with a calcia-doped zirconia-oxygen cell while measuring electrical conductivity of iron-bearing silicates at high temperature (greater than 1000 K). The fo{sub 2} calculated thermodynamically from CO/CO{sub 2} mixing ratios agreed well with measurements made with the zirconia cell at 1473 K, except for fo{sub 2} greater than 10{sup -4} Pa, where, on a log{sub 10} scale, mixing-ratio errors were as large as +- 0.2. These errors are attributed to oxygen contamination in the CO{sub 2} and to mobile carbon deposits that formed in the apparatus.

Electrical conductivity measurements in shock compressed liquid nitrogen

International Nuclear Information System (INIS)

Hamilton, D.C.; Mitchell, A.C.; Nellis, W.J.

1985-06-01

The electrical conductivity of shock compressed liquid nitrogen was measured in the pressure range 20 to 50 GPa using a two-stage light-gas gun. The conductivities covered a range 4 x 10 -2 to 1 x 10 2 ohm -1 cm -1 . The data are discussed in terms of a liquid semiconductor model below the onset of the dissociative phase transition at 30 GPa. 15 refs., 1 fig

Galectin-3 levels relate in children to total body fat, abdominal fat, body fat distribution, and cardiac size.

Science.gov (United States)

Dencker, Magnus; Arvidsson, Daniel; Karlsson, Magnus K; Wollmer, Per; Andersen, Lars B; Thorsson, Ola

2018-03-01

Galectin-3 has recently been proposed as a novel biomarker for cardiovascular disease in adults. The purpose of this investigation was to assess relationships between galectin-3 levels and total body fat, abdominal fat, body fat distribution, aerobic fitness, blood pressure, left ventricular mass, left atrial size, and increase in body fat over a 2-year period in a population-based sample of children. Our study included 170 children aged 8-11 years. Total fat mass and abdominal fat were measured by dual-energy x-ray absorptiometry (DXA). Body fat distribution was expressed as abdominal fat/total fat mass. Maximal oxygen uptake was assessed by indirect calorimetry during a maximal exercise test and scaled to body mass. Systolic and diastolic blood pressure and pulse pressure were measured. Left atrial size, left ventricular mass, and relative wall thickness were measured by echocardiography. Frozen serum samples were analyzed for galectin-3 by the Proximity Extension Assay technique. A follow-up DXA scan was performed in 152 children 2 years after the baseline exam. Partial correlations, with adjustment for sex and age, between galectin-3 versus body fat measurements indicated weak to moderate relationships. Moreover, left atrial size, left ventricular mass, and relative wall thickness and pulse pressure were also correlated with galectin-3. Neither systolic blood pressure nor maximal oxygen uptake was correlated with galectin-3. There was also a correlation between galectin-3 and increase in total body fat over 2 years, while no such correlations were found for the other fat measurements. More body fat and abdominal fat, more abdominal body fat distribution, more left ventricular mass, and increased left atrial size were all associated with higher levels of galectin-3. Increase in total body fat over 2 years was also associated with higher levels of galectin-3. What is Known: • Galectin-3 has been linked to obesity and been proposed to be a novel biomarker

The Thermal Electrical Conductivity Probe (TECP) for Phoenix

Science.gov (United States)

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

2009-01-01

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

High-performance electrically conductive silver paste prepared by silver-containing precursor

Energy Technology Data Exchange (ETDEWEB)

Liu, Jianguo; Cao, Yu; Li, Xiangyou; Wang, Xiaoye; Zeng, Xiaoyan [Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Wuhan (China)

2010-09-15

A high-performance electrically conductive silver paste with no solid particles before drying and/or sintering is developed, in which silver-containing precursor is employed as conductive functional phase. Thermogravimetry analysis, volume electrical resistivity tests and sintering experiments show that the paste with about 14 wt.% silver pristine content is able to achieve the volume electrical resistivity of (2-3) x 10{sup -5} {omega} cm after it is sintered at 220 C. A micro-pen direct-writing process indicates that it is very suitable for the fabrication of high-resolution (25 {mu}m) and high-integration devices and apparatus. (orig.)

Thermal stability and electrical conductivity in polyethers-molybdenum disulfide nanocomposites

International Nuclear Information System (INIS)

Mirabal, N.; Aguirre, P.; Santa Ana, M.A.; Benavente, E.; Gonzalez, Guillermo

2003-01-01

The intercalation of poly(ethylene oxide) (PEO), into molybdenum disulfide, like that of other electron pair donors, leads to mixed ionic-electronic conductors. At room temperature, intercalates show electrical and lithium-ion conductivities better than MoS 2 and bulk PEO composites, respectively. However, these products are known to be sensitive to temperature; indeed, in the range 80-100 deg. C an irreversible decrease of the electrical conductivity is observed. In order to investigate these features, the thermal behavior of a series of polyethers of different molecular weights (poly(ethylene glycol) (Mw 3400) and PEO with Mw in the range 10 4 -4x10 6 , pure and intercalated in MoS 2 , (Li x (MoS 2 )(polyether) y with x∼0.1 and y=1.1-1.5), was comparatively analyzed. Furthermore, the effect of thermal treatment of the sample on the electrical conductivity was studied for one of the intercalated products. Results indicate that irreversible changes, detected by both loss of weight and a significant conductivity lowering, are occurring in the range from about 100 deg. C to a temperature near to the decomposition point of the organic phase at about 350 deg. C

Total body fat as a possible indicator of metabolic syndrome in adults

Directory of Open Access Journals (Sweden)

Edgar Navarro Lechuga

2016-09-01

Full Text Available Introduction: The metabolic syndrome is a set of factors related to insulin resistance, which increases the likelihood of coronary events. It is important timely onset identifying to reduce its prevalence. Objective: To explore the percentage of total body fat as indicator of metabolic syndrome in adults from Soledad, Colombia. Material and Methods: Cross-sectional study. n=99 adults (non-pregnant, nor subjects with psychomotor disturbances. Blood samples were taken: total cholesterol, HDL; triglycerides and glucose. Waist circumference, Body Mass Index and body fat by bioimpedance and skinfold thickness were measured. Diagnosis of metabolic syndrome was made according to NHLBI/AHA, ATP III and IDF criteria. Subjects with and without metabolic syndrome according to total body fat averages were compared. Results: The average percentage of body fat was higher (p0.05 in the classification according to ATP III in women, where the average fat percentage was 39.31 % in those with metabolic syndrome and 37.7% in those not suffering. Conclusions: Subjects with metabolic syndrome have higher mean total body fat, significantly, compared with those who did not, so it could be considered the values of total body fat obtained by bioimpedance as future indicators of metabolic syndrome, both as screening and control.

Electrical conductivity enhancement by boron-doping in diamond using first principle calculations

Science.gov (United States)

Ullah, Mahtab; Ahmed, Ejaz; Hussain, Fayyaz; Rana, Anwar Manzoor; Raza, Rizwan

2015-04-01

Boron doping in diamond plays a vital role in enhancing electrical conductivity of diamond by making it a semiconductor, a conductor or even a superconductor. To elucidate this fact, partial and total density of states has been determined as a function of B-content in diamond. Moreover, the orbital charge distributions, B-C bond lengths and their population have been studied for B-doping in pristine diamond thin films by applying density functional theory (DFT). These parameters have been found to be influenced by the addition of different percentages of boron atoms in diamond. The electronic density of states, B-C bond situations as well as variations in electrical conductivities of diamond films with different boron content and determination of some relationship between these parameters were the basic tasks of this study. Diamond with high boron concentration (∼5.88% B-atoms) showed maximum splitting of energy bands (caused by acceptor impurity states) at the Fermi level which resulted in the enhancement of electron/ion conductivities. Because B atoms either substitute carbon atoms and/or assemble at grain boundaries (interstitial sites) inducing impurity levels close to the top of the valence band. At very high B-concentration, impurity states combine to form an impurity band which accesses the top of the valence band yielding metal like conductivity. Moreover, bond length and charge distributions are found to decrease with increase in boron percentage in diamond. It is noted that charge distribution decreased from +1.89 to -1.90 eV whereas bond length reduced by 0.04 Å with increasing boron content in diamond films. These theoretical results support our earlier experimental findings on B-doped diamond polycrystalline films which depict that the addition of boron atoms to diamond films gives a sudden fall in resistivity even up to 105 Ω cm making it a good semiconductor for its applications in electrical devices.

In-situ electric field in human body model in different postures for wireless power transfer system in an electrical vehicle

International Nuclear Information System (INIS)

Shimamoto, Takuya; Laakso, Ilkka; Hirata, Akimasa

2015-01-01

The in-situ electric field of an adult male model in different postures is evaluated for exposure to the magnetic field leaked from a wireless power transfer system in an electrical vehicle. The transfer system is located below the centre of the vehicle body and the transferred power and frequency are 7 kW and 85 kHz, respectively. The in-situ electric field is evaluated for a human model (i) crouching near the vehicle, (ii) lying on the ground with or without his arm stretched, (iii) sitting in the driver’s seat, and (iv) standing on a transmitting coil without a receiving coil. In each scenario, the maximum in-situ electric fields are lower than the allowable limit prescribed by international guidelines, although the local magnetic field strength in regions of the human body is higher than the allowable external magnetic field strength. The highest in-situ electric field is observed when the human body model is placed on the ground with his arm extended toward the coils, because of a higher magnetic field around the arm. (paper)

In-situ electric field in human body model in different postures for wireless power transfer system in an electrical vehicle.

Science.gov (United States)

Shimamoto, Takuya; Laakso, Ilkka; Hirata, Akimasa

2015-01-07

The in-situ electric field of an adult male model in different postures is evaluated for exposure to the magnetic field leaked from a wireless power transfer system in an electrical vehicle. The transfer system is located below the centre of the vehicle body and the transferred power and frequency are 7 kW and 85 kHz, respectively. The in-situ electric field is evaluated for a human model (i) crouching near the vehicle, (ii) lying on the ground with or without his arm stretched, (iii) sitting in the driver's seat, and (iv) standing on a transmitting coil without a receiving coil. In each scenario, the maximum in-situ electric fields are lower than the allowable limit prescribed by international guidelines, although the local magnetic field strength in regions of the human body is higher than the allowable external magnetic field strength. The highest in-situ electric field is observed when the human body model is placed on the ground with his arm extended toward the coils, because of a higher magnetic field around the arm.

Study on Exploding Wire Compression for Evaluating Electrical Conductivity in Warm-Dense Diamond-Like-Carbon

International Nuclear Information System (INIS)

Sasaki, Toru; Takahashi, Kazumasa; Kudo, Takahiro; Kikuchi, Takashi; Aso, Tsukasa; Harada, Nob.; Fujioka, Shinsuke; Horioka, Kazuhiko

2016-01-01

To improve a coupling efficiency for the fast ignition scheme of the inertial confinement fusion, fast electron behaviors as a function of an electrical conductivity are required. To evaluate the electrical conductivity for low-Z materials as a diamond-like-carbon (DLC), we have proposed a concept to investigate the properties of warm dense matter (WDM) by using pulsed-power discharges. The concept of the evaluation of DLC for WDM is a shock compression driven by an exploding wire discharge with confined by a rigid capillary. The qualitatively evaluation of the electrical conductivity for the WDM DLC requires a small electrical conductivity of the exploding wire. To analyze the electrical conductivity of exploding wire, we have demonstrated an exploding wire discharge in water for gold. The results indicated that the electrical conductivity of WDM gold for 5000 K of temperature has an insulator regime. It means that the shock compression driven by the exploding wire discharge with confined by the rigid capillary is applied for the evaluation of electrical conductivity for WDM DLC. (paper)

Development of electrical insulation and conduction coating for fusion experimental devices

Energy Technology Data Exchange (ETDEWEB)

Onozuka, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Tsujimura, S. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Toyoda, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Inoue, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Abe, T. [Japan Atomic Energy Research Inst., Naka (Japan); Murakami, Y. [Japan Atomic Energy Research Inst., Naka (Japan)

1995-12-31

Development of electrical insulation and conduction methods that can be applied for large components have been investigated for future large fusion experimental devices. A thermal spraying method is employed to coat the insulation or conduction materials on the structural components. Al{sub 2}O{sub 3} has been selected as an insulation material, while Cr{sub 3}C{sub 2}-NiCr and WC-NiCr have been chosen as conduction materials. These materials were coated on stainless steel base plates to examine the basic characteristics of the coated layers, such as their adhesive strength to the base plate and electrical resistance. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed sufficient frictional properties. The applicability of the spraying method was examined on a 100mm x 1000mm surface and found to be applicable for large surfaces in fusion experimental devices. (orig.).

Development of electrical insulation and conduction coating for fusion experimental devices

International Nuclear Information System (INIS)

Onozuka, M.; Tsujimura, S.; Toyoda, M.; Inoue, M.; Abe, T.; Murakami, Y.

1995-01-01

Development of electrical insulation and conduction methods that can be applied for large components have been investigated for future large fusion experimental devices. A thermal spraying method is employed to coat the insulation or conduction materials on the structural components. Al 2 O 3 has been selected as an insulation material, while Cr 3 C 2 -NiCr and WC-NiCr have been chosen as conduction materials. These materials were coated on stainless steel base plates to examine the basic characteristics of the coated layers, such as their adhesive strength to the base plate and electrical resistance. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed sufficient frictional properties. The applicability of the spraying method was examined on a 100mm x 1000mm surface and found to be applicable for large surfaces in fusion experimental devices. (orig.)

Soil water sensor response to bulk electrical conductivity

Science.gov (United States)

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

Challenges associated with nerve conduction block using kilohertz electrical stimulation

Science.gov (United States)

Patel, Yogi A.; Butera, Robert J.

2018-06-01

Neuromodulation therapies, which electrically stimulate parts of the nervous system, have traditionally attempted to activate neurons or axons to restore function or alleviate disease symptoms. In stark contrast to this approach is inhibiting neural activity to relieve disease symptoms and/or restore homeostasis. One potential approach is kilohertz electrical stimulation (KES) of peripheral nerves—which enables a rapid, reversible, and localized block of conduction. This review highlights the existing scientific and clinical utility of KES and discusses the technical and physiological challenges that must be addressed for successful translation of KES nerve conduction block therapies.

Application of Electromagnetic Induction to Monitor Changes in Soil Electrical Conductivity Profiles in Arid Agriculture

KAUST Repository

Jadoon, K.Z.

2015-09-06

In this research, multi-configuration electromagnetic induction (EMI) measurements were conducted in a corn field to estimate variation in soil electrical conductivity profiles in the roots zone. Electromagnetic forward model based on the full solution of Maxwell\\'s equation was used to simulate the apparent electrical conductivity measured with EMI system (the CMD mini-Explorer). Joint inversion of multi-configuration EMI measurements were performed to estimate the vertical soil electrical conductivity profiles. The inversion minimizes the misfit between the measured and modeled soil apparent electrical conductivity by DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm, which is based on Bayesain approach. Results indicate that soil electrical conductivity profiles have low values close to the corn plants, which indicates loss of soil moisture due to the root water uptake. These results offer valuable insights into future potential and emerging challenges in the development of joint analysis of multi-configuration EMI measurements to retrieve effective soil electrical conductivity profiles.

High Resolution Global Electrical Conductivity Variations in the Earth's Mantle

Science.gov (United States)

Kelbert, A.; Sun, J.; Egbert, G. D.

2013-12-01

Electrical conductivity of the Earth's mantle is a valuable constraint on the water content and melting processes. In Kelbert et al. (2009), we obtained the first global inverse model of electrical conductivity in the mantle capable of providing constraints on the lateral variations in mantle water content. However, in doing so we had to compromise on the problem complexity by using the historically very primitive ionospheric and magnetospheric source assumptions. In particular, possible model contamination by the auroral current systems had greatly restricted our use of available data. We have now addressed this problem by inverting for the external sources along with the electrical conductivity variations. In this study, we still focus primarily on long period data that are dominated by quasi-zonal source fields. The improved understanding of the ionospheric sources allows us to invert the magnetic fields directly, without a correction for the source and/or the use of transfer functions. It allows us to extend the period range of available data to 1.2 days - 102 days, achieving better sensitivity to the upper mantle and transition zone structures. Finally, once the source effects in the data are accounted for, a much larger subset of observatories may be used in the electrical conductivity inversion. Here, we use full magnetic fields at 207 geomagnetic observatories, which include mid-latitude, equatorial and high latitude data. Observatory hourly means from the years 1958-2010 are employed. The improved quality and spatial distribution of the data set, as well as the high resolution modeling and inversion using degree and order 40 spherical harmonics mapped to a 2x2 degree lateral grid, all contribute to the much improved resolution of our models, representing a conceptual step forward in global electromagnetic sounding. We present a fully three-dimensional, global electrical conductivity model of the Earth's mantle as inferred from ground geomagnetic

Redox transitions in strontium vanadates: Electrical conductivity and dimensional changes

International Nuclear Information System (INIS)

Macías, J.; Yaremchenko, A.A.; Frade, J.R.

2014-01-01

Highlights: • Electrical conductivity and thermal expansion of strontium vanadates are measured. • Conductivity of SrVO 3−δ is 10 6 –10 8 times higher compared to Sr 2 V 2 O 7 and Sr 3 V 2 O 8 . • Sr 2 V 2 O 7 transforms on reduction to SrVO 3−δ via (5Sr 3 V 2 O 8 + SrV 6 O 11 ) intermediate. • This process is kinetically stagnated due to good redox stability of Sr 3 V 2 O 8 . • Large volume changes on Sr 2 V 2 O 7 ↔ SrVO 3 transformation are confirmed by dilatometry. - Abstract: The reversibility of redox-induced phase transformations and accompanying electrical conductivity and dimensional changes in perovskite-type SrVO 3−δ , a parent material for a family of potential solid oxide fuel cell anode materials, were evaluated employing X-ray diffraction, thermal analysis, dilatometry and electrical measurements. At 873–1273 K, the electrical conductivity of SrVO 3−δ is metallic-like and 6–8 orders of magnitude higher compared to semiconducting V 5+ -based strontium pyrovanadate Sr 2 V 2 O 7 and strontium orthovanadate Sr 3 V 2 O 8 existing under oxidizing conditions. SrVO 3−δ is easily oxidized to a pyrovanadate phase at atmospheric oxygen pressure. Inverse reduction in 10%H 2 –90%N 2 atmosphere occurs in two steps through (5Sr 3 V 2 O 8 + SrV 6 O 11 ) intermediate. As Sr 3 V 2 O 8 is relatively stable even under reducing conditions, the perovskite phase and its high level of electrical conductivity cannot be recovered completely in a reasonable time span at temperatures ⩽1273 K. Dilatometric studies confirmed that SrVO 3 ↔ Sr 2 V 2 O 7 redox transformation is accompanied with significant dimensional changes. Their extent depends on the degree of phase conversion and, apparently, on microstructural features

Computer simulation of induced electric currents and fields in biological bodies by 60 Hz magnetic fields

International Nuclear Information System (INIS)

Xi Weiguo; Stuchly, M.A.; Gandhi, O.P.

1993-01-01

Possible health effects of human exposure to 60 Hz magnetic fields are a subject of increasing concern. An understanding of the coupling of electromagnetic fields to human body tissues is essential for assessment of their biological effects. A method is presented for the computerized simulation of induced electric currents and fields in bodies of men and rodents from power-line frequency magnetic fields. In the impedance method, the body is represented by a 3 dimensional impedance network. The computational model consists of several tens of thousands of cubic numerical cells and thus represented a realistic shape. The modelling for humans is performed with two models, a heterogeneous model based on cross-section anatomy and a homogeneous one using an average tissue conductivity. A summary of computed results of induced electric currents and fields is presented. It is confirmed that induced currents are lower than endangerous current levels for most environmental exposures. However, the induced current density varies greatly, with the maximum being at least 10 times larger than the average. This difference is likely to be greater when more detailed anatomy and morphology are considered. 15 refs., 2 figs., 1 tab

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

International Nuclear Information System (INIS)

Kamide, Y.; Vickrey, J.F.

1983-01-01

Data from continuous scans of the Chatanika radar beam along the magnetic meridian plane are used to the determine the latitudinal profile of height-integrated ionospheric conductivities and horizontal electric fields, from which the latitudinal distribution of ionospheric currents is deduced. The observations cover invariant latitudes between 62 0 and 68 0 , where the IMS Alaska meridian chain of magnetometers was also in operation. Although the conductivities and the electric fields are interrelated, the relative importance of the two in driving the eastward and westward auroral electrojet currents can be assessed. It is found that for moderate and large current densities (i.e., > or approx. =0.2 A/m), the northward electric field strength increases as the magnitude of the eastward electrojet in the evening sector increases. The height-integrated Hall conductivity stays generally at the level of 10 mhos even when the current density becomes as large as 1 A/m. However, when the eastward electrojet is small, substantial electric fields of 10-20 mV/m may still exist as if the magnetosphere has a persistent voltage source. There appear to be two distinct components to the westward electrojet. In the midnight and early morning sestors (>0300 MLT) intensity is characterized by a weak southward electric field and a high Hall conductivity, whereas its late morning portion (>0300 MLT) is dominated by a strong southward electric field

The electrical conductivity of a weakly non-ideal, dense plasma

NARCIS (Netherlands)

Rosado, R.J.; Leclair, J.; Schram, D.C.

1977-01-01

The electrical conductance of a non-ideal plasma was measured and compared with Spitzer's formula for ideal plasmas and a correction to this formula proposed by Rovinskii. The measured conductance proved to agree better with the Spitzer result

Reinforced carbon nanotubes as electrically conducting and flexible films for space applications.

Science.gov (United States)

Atar, Nurit; Grossman, Eitan; Gouzman, Irina; Bolker, Asaf; Hanein, Yael

2014-11-26

Chemical vapor deposition (CVD)-grown entangled carbon nanotube (CNT) sheets are characterized by high electrical conductivity and durability to bending and folding. However, since freestanding CNT sheets are mechanically weak, they cannot be used as stand-alone flexible films. In this work, polyimide (PI) infiltration into entangled cup-stacked CNT (CSCNT) sheets was studied to form electrically conducting, robust, and flexible films for space applications. The infiltration process preserved CNTs' advantageous properties (i.e., conductivity and flexibility), prevented CNT agglomeration, and enabled CNT patterning. In particular, the CNT-PI films exhibited ohmic electrical conductance in both the lateral and vertical directions, with a sheet resistivity as low as 122 Ω/□, similar to that of as-grown CNT sheets, with minimal effect of the insulating matrix. Moreover, this high conductivity was preserved under mechanical and thermal manipulations. These properties make the reported CNT-PI films excellent candidates for applications where flexibility, thermal stability, and electrical conductivity are required. Particularly, the developed CNT-PI films were found to be durable in space environment hazards such as high vacuum, thermal cycling, and ionizing radiation, and hence they are suggested as an alternative for the electrostatic discharge (ESD) protection layer in spacecraft thermal blankets.

Electrical conductivity improvement of strontium titanate doped lead vanadate glasses by nanocrystallization

Energy Technology Data Exchange (ETDEWEB)

El-Desoky, M.M., E-mail: mmdesoky@gmail.co [Physics Department, Faculty of Education, Suez Canal University, El-Arish (Egypt); Zayed, H.S.S.; Ibrahim, F.A.; Ragab, H.S. [Physics Department, Faculty of Education, Suez Canal University, El-Arish (Egypt)

2009-11-15

The structural and electrical conductivity (sigma) of annealed SrTiO{sub 3}-PbO{sub 2}-V{sub 2}O{sub 5} glasses were studied. The annealing of initially glass samples leads to formation of nanocrystalline grains embedded in the glassy matrix. XRD patterns of the glass-ceramic samples show that nanocrystals were embedded in the glassy matrix with an average grain size of 32 nm. The glass-ceramic nanocrystals obtained by annealing at temperatures close to the crystallization temperature T{sub c} exhibit enhancement of electrical conductivity up to four orders of magnitude than initially glasses. The enhancement of the electrical conductivity due to annealing was attributed to two interdependent factors: (i) an increase of concentration of V{sup 4+}-V{sup 5+} pairs; and (ii) formation of defective, well-conducting regions along the glass-crystallites interfaces. From the conductivity temperature relation, it was found that small polaron hopping model was applicable at temperature above theta{sub D}/2 (theta{sub D}, the Debye temperature). The electrical conduction at T >theta{sub D}/2 was due to non-adiabatic small polaron hopping (SPH) of electrons between vanadium ions. The parameters obtained from the fits of the experimental data to this model appear reasonable and are consistent with glass composition.

Electrical conductivity improvement of strontium titanate doped lead vanadate glasses by nanocrystallization

International Nuclear Information System (INIS)

El-Desoky, M.M.; Zayed, H.S.S.; Ibrahim, F.A.; Ragab, H.S.

2009-01-01

The structural and electrical conductivity (σ) of annealed SrTiO 3 -PbO 2 -V 2 O 5 glasses were studied. The annealing of initially glass samples leads to formation of nanocrystalline grains embedded in the glassy matrix. XRD patterns of the glass-ceramic samples show that nanocrystals were embedded in the glassy matrix with an average grain size of 32 nm. The glass-ceramic nanocrystals obtained by annealing at temperatures close to the crystallization temperature T c exhibit enhancement of electrical conductivity up to four orders of magnitude than initially glasses. The enhancement of the electrical conductivity due to annealing was attributed to two interdependent factors: (i) an increase of concentration of V 4+ -V 5+ pairs; and (ii) formation of defective, well-conducting regions along the glass-crystallites interfaces. From the conductivity temperature relation, it was found that small polaron hopping model was applicable at temperature above θ D /2 (θ D , the Debye temperature). The electrical conduction at T >θ D /2 was due to non-adiabatic small polaron hopping (SPH) of electrons between vanadium ions. The parameters obtained from the fits of the experimental data to this model appear reasonable and are consistent with glass composition.

Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon [Hanyang University, 408-2, 4th Engineering Bldg, Sa 3-dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of); Cho, Jeon-Wook; Ryoo, Hee-Suk [Korea Electrotechnology Research Institute, Changwon, Gyungnam 641-120 (Korea, Republic of); Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr [Hanyang University, 408-2, 4th Engineering Bldg, Sa 3-dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of)

2013-11-15

Highlights: •The electrical conductivity of PPLP in LN{sub 2} was successfully measured. •Based on the measured value of PPLP, DC field analysis was performed. •The electric field distribution was altered according to the DC applying stages. •The maximum electric field was observed during polarity reversal situation. •DC field analysis is important to determine the optimum design of DC HTS devices. -- Abstract: High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN{sub 2}). Electrical conductivity of PPLP in LN{sub 2} has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN{sub 2} were presented in this paper. Based on the experimental works, DC electric

Total Body Opacification 'Technique Neonatal Adrenal Haemorrhage

African Journals Online (AJOL)

1971-12-11

Dec 11, 1971 ... A case is reported illustrating the possible usefulness of total body opacification in the diagnosis of neonatal adrenal haemorrhage. To derive maximum benefit from this principle, the routine use of an early film coupled with high dosage is urged whenever an intravenous pyelogram is performed for ...

Synthesis, structure and total conductivity of A-site doped LaTiO3−δ perovskites

International Nuclear Information System (INIS)

Bradha, M.; Hussain, S.; Chakravarty, Sujay; Amarendra, G.; Ashok, Anuradha

2015-01-01

Highlights: • A-site divalent alkaline earth metal doped LaTiO 3−δ perovskites were synthesised by sol–gel method. • Structural studies revealed no change in crystal symmetry but change in cell dimensions after doping. • After doping divalent cations in A-site, an enhancement in total conductivity was observed in LaTiO 3−δ . • Temperature dependent electrical property was observed in all synthesised perovskites. - Abstract: Oxygen deficient perovskites LaTiO 3−δ and La 0.8 A 0.2 TiO 3−δ (A = Ba, Sr, Ca) were synthesized by sol–gel method. The effect of divalent dopants on microstructure is investigated in detail using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The oxidation states of La 3+ and Ti 3+ ions have been deduced using X-ray Photoelectron Spectroscopy (XPS). Impedance spectroscopy was used to analyze the total conductivity, an increase in conductivity was observed after doping in the A-site with divalent cations Ba, Ca and Sr. Among the investigated perovskites La 0.8 Ca 0.2 TiO 3−δ exhibited the maximum conductivity of 1.22 × 10 −2 S/cm in air atmosphere at 650 °C

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

Science.gov (United States)

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

2018-03-01

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

Shear-induced changes of electrical conductivity in suspensions

Energy Technology Data Exchange (ETDEWEB)

Crawshaw, John; Meeten, Gerald [Schlumberger Cambridge Research, Cambridge (United Kingdom)

2006-12-15

The effect of shear on electrical conductivity (rheo-conduction) is studied to give information about particle behaviour in suspensions. Past work is reviewed, and expressions are derived for the rheo-conduction of a suspension of nonconducting spheroids in a conducting matrix for current flow, parallel and normal to the suspension flow direction. A simple apparatus to study rheo-conduction in pipe flow is described, and measurements of steady and time-dependent effects are reported for various suspensions of colloidal particles. Suspensions of anisometric rod- and platelike particles at low concentrations showed rheo-conductive changes of sign, magnitude and relaxation that were consistent with the particle shape, concentration and interactions. The rheo-conductive response decreased with increasing volume fraction for platelike kaolinite particles, attributed to orientational jamming. Spherical latex particles gave unexpected rheo-conductive changes consistent with shear disruption of a conductive network of particles. It is concluded that rheo-conduction measurements are a useful adjunct to conventional rheometry. (orig.)

Infrared transparency and electrical conductivity of non-stoichiometric InxOy films

International Nuclear Information System (INIS)

Joseph, Shay; Berger, Shlomo

2010-01-01

In an effort to achieve both high infrared transparency and electrical conductivity, In x O y films having different oxygen atomic fractions, ranging from 0.27 to 0.6 were prepared. From AC electrical measurements it was determined that conductivity of In x O y films, having oxygen atomic fraction near 0.6, is governed by the hopping conduction mechanism via energy states located in the band gap. Conductivity of In x O y films having non-stoichiometric compositions was found to be governed by the free band conduction mechanism. The conduction activation energy was decreased from about 0.47 eV to about 0.02 eV as the deviation of the oxygen atomic fraction from the stoichiometric value of 0.6 was increased. The dielectric function of the films was determined by applying the Drude-Lorentz model to ellipsometric measurements in the infrared and visible wavelengths. In the visible range, the major source for optical transmission loss is interband absorption, which was modeled by the Lorentz model. In the infrared range, optical absorption was measured and attributed to the presence of free charge carriers according to the Drude model. Fitting the model to the optical measurements required a correction factor, which was correlated with the films polarizability. In order to determine the optimal tradeoff between optical transparency in the infrared and electrical conductivity, which were found to be affected mainly by the oxygen concentration in the films, a figure of merit parameter was established. It was found that by introducing non-stoichiometry in the form of oxygen deficiency, the electrical conductivity was improved by as much as two orders of magnitude while the infrared transparency was decreased by no more than 30% with respect to stoichiometric In 2 O 3 films.

A Route for Polymer Nanocomposites with Engineered Electrical Conductivity and Percolation Threshold

Directory of Open Access Journals (Sweden)

Lawrence T. Drzal

2010-02-01

Full Text Available Polymer nanocomposites with engineered electrical properties can be made by tuning the fabrication method, processing conditions and filler’s geometric and physical properties. This work focuses on investigating the effect of filler’s geometry (aspect ratio and shape, intrinsic electrical conductivity, alignment and dispersion within the polymer, and polymer crystallinity, on the percolation threshold and electrical conductivity of polypropylene based nanocomposites. The conductive reinforcements used are exfoliated graphite nanoplatelets, carbon black, vapor grown carbon fibers and polyacrylonitrile carbon fibers. The composites are made using melt mixing followed by injection molding. A coating method is also employed to improve the nanofiller’s dispersion within the polymer and compression molding is used to alter the nanofiller’s alignment.

Modeling electrical conductivities of nanocomposites with aligned carbon nanotubes

International Nuclear Information System (INIS)

Bao, W S; Meguid, S A; Zhu, Z H; Meguid, M J

2011-01-01

We have developed an improved three-dimensional (3D) percolation model to investigate the effect of the alignment of carbon nanotubes (CNTs) on the electrical conductivity of nanocomposites. In this model, both intrinsic and contact resistances are considered, and a new method of resistor network recognition that employs periodically connective paths is developed. This method leads to a reduction in the size effect of the representative cuboid in our Monte Carlo simulations. With this new technique, we were able to effectively analyze the effects of the CNT alignment upon the electrical conductivity of nanocomposites. Our model predicted that the peak value of the conductivity occurs for partially aligned rather than perfectly aligned CNTs. It has also identified the value of the peak and the corresponding alignment for different volume fractions of CNTs. Our model works well for both multi-wall CNTs (MWCNTs) and single-wall CNTs (SWCNTs), and the numerical results show a quantitative agreement with existing experimental observations.

Serum protein concentration in low-dose total body irradiation of normal and malnourished rats

International Nuclear Information System (INIS)

Viana, W.C.M.; Lambertz, D.; Borges, E.S.; Neto, A.M.O.; Lambertz, K.M.F.T.; Amaral, A.

2016-01-01

Among the radiotherapeutics' modalities, total body irradiation (TBI) is used as treatment for certain hematological, oncological and immunological diseases. The aim of this study was to evaluate the long-term effects of low-dose TBI on plasma concentration of total protein and albumin using prematurely and undernourished rats as animal model. For this, four groups with 9 animals each were formed: Normal nourished (N); Malnourished (M); Irradiated Normal nourished (IN); Irradiated Malnourished (IM). At the age of 28 days, rats of the IN and IM groups underwent total body gamma irradiation with a source of cobalt-60. Total protein and Albumin in the blood serum was quantified by colorimetry. This research indicates that procedures involving low-dose total body irradiation in children have repercussions in the reduction in body-mass as well as in the plasma levels of total protein and albumin. Our findings reinforce the periodic monitoring of total serum protein and albumin levels as an important tool in long-term follow-up of pediatric patients in treatments associated to total body irradiation. - Highlights: • Low-dose total body irradiation (TBI) in children have repercussions in their body-mass. • Long-term total protein and albumin levels are affected by TBI. • The monitoring of total protein and albumin levels are useful in the follow-up of TBI pediatric patients.

Synthesis and electrical conductivity of nanocrystalline tetragonal FeS

International Nuclear Information System (INIS)

Zeng Shu-Lin; Wang Hui-Xian; Dong Cheng

2014-01-01

A convenient method for synthesis of tetragonal FeS using iron powder as iron source, is reported. Nanocrystalline tetragonal FeS samples were successfully synthesized by reacting metallic iron powder with sodium sulfide in acetate buffer solution. The obtained sample is single-phase tetragonal FeS with lattice parameters a = 0.3767 nm and c = 0.5037 nm, as revealed by X-ray diffraction. The sample consists of flat nanosheets with lateral dimensions from 20 nm up to 200 nm and average thickness of about 20 nm. We found that tetragonal FeS is a fairly good conductor from the electrical resistivity measurement on a pellet of the nanosheets. The temperature dependence of conductivity of the pellet was well fitted using an empirical equation wherein the effect of different grain boundaries was taken into consideration. This study provides a convenient, economic way to synthesize tetragonal FeS in a large scale and reports the first electrical conductivity data for tetragonal FeS down to liquid helium temperature. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Effects of zilpaterol hydrochloride on methane production, total body oxygen consumption, and blood metabolites in finishing beef steers

Science.gov (United States)

An indirect calorimetry experiment was conducted to determine the effects of feeding zilpaterol hydrochloride (ZH) for 20 d on total body oxygen consumption, respiratory quotient, methane production, and blood metabolites in finishing beef steers. Sixteen Angus steers (initial BW = 555 ± 12.7 kg) w...

Thermal conductivity and electrical resistivity of cadmium arsenide (Cd3As2) in the temperature range 4.2-40K1

International Nuclear Information System (INIS)

Bartkowski, K.; Ratalowicz, J.; Zdanowicz, W.

1986-01-01

Results on electrical resistivity and thermal conductivity measured in the temperature range 4.2-40 K are presented for single-crystal and polycrystalline samples of Cd 3 As 2 . Hall effect has been studied at temperatures of 4.2, 77, and 300K. The calculated value of the conduction electron concentration was in the range 1.87-1.95 10 24 m -3 . Electrical resistivity of all investigated samples was independent of temperature up to about 10K and increased slowsly at higher temperatures. The thermal conductivity shows a maximum in the region in which the lattice component of thermal conductivity dominates. The strong anistropy of the lattice component determines the anisotropy of the total thermal conductivity. The electronic component of thermal conductivity does not exhibit any anisotropy and shows a maximum at a temperature of about 300 K

The effect of an alternating electric field on a totally ionised plasma; Action d'un champ electrique alternatif sur un plasma totalement ionise

Energy Technology Data Exchange (ETDEWEB)

Baglin, H; Brin, A; Ozias, Y; Salmon, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Delcroix, J L [Ecole Normale Superieure, 75 - Paris (France)

1960-07-01

The equation giving the distribution function of the electrons in a steady-state, for a fully ionized plasma in an a.c. field, are provided from the Fokker-Planck equation. The electric conductivity is complex and depends on the frequency. (author) [French] L'equation qui donne la fonction de distribution des electrons dans un etat stationnaire pour un plasma totalement ionise dans un champ electrique alternatif est fournie par l'equation de Fokker-Planck. La conductibilite electrique est complexe et depend de la frequence. (auteur)

Electrical properties of conducting loads produced from polyaniline deposited in natural fibers and nanoclays

International Nuclear Information System (INIS)

Kosenhoski, Dirlaine; Saade, Wesley; Pinto, Camila P.; Becker, Daniela; Dalmolin, Carla; Pachekoski, Wagner M.

2015-01-01

Conducting polymers are known for their excellent magnetic and electrical properties, but they still are an expensive and limited choice to their use as a conducting load for composite materials. An alternative to optimize the electrical conductivity of polymeric composites is the deposition of a conducting polymer on materials already used as loads, as the deposition on natural fibers or the encapsulation of polymeric chains in the voids of host structures. In this work, bananastem fiber and montmorillonite nanoclay (MMT) were used as host structures for polyaniline synthesis in order to produce conducting loads. Samples were characterized by FT-IR and X-Rays Diffraction in order to confirm the formation of polyanilina / bananastem fibers or polyanilina / nanoclays loads. Influence on the electrical properties of the composites were evaluated by Electrochemical Impedance Spectroscopy (EIS), showing the maintenance of the electric conductivity of polyaniline and its potential use as a load for the formation of conducting composites. (author)

Total body irradiation as a form of preparation for bone marrow transplantation

International Nuclear Information System (INIS)

Inoue, Toshihiko

1987-01-01

The history of total body irradiation and bone marrow transplantation is surprisingly old. Following the success of Thomas et al. in the 1970s, bone marrow transplantation appeared to be the sole curative treatment modality for high-risk leukemia. A supralethal dose of total body irradiation was widely accepted as a form of preparation for bone marrow transplantation. In this paper, I described the present status of bone marrow transplantation for leukemia patients in Japan based on the IVth national survey. Since interstitial pneumonitis was one of the most life threatening complications after bone marrow transplantation, I mentioned the dose, dose-rate and fraction of total body irradiation in more detail. In addition, I dealt with some problems of the total body irradiation, such as dose prescription, compensating contour as well as inhomogeneity, and shielding for the highrisk organs. (author) 82 refs

Statistical properties of Joule heating rate, electric field and conductances at high latitudes

Directory of Open Access Journals (Sweden)

A. T. Aikio

2009-07-01

Full Text Available Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox and from similar sunspot conditions (about 1.5 years before the sunspot minimum providing an excellent set of data to study the MLT and Kp dependence of parameters with high temporal and spatial resolution. All the parameters show a clear MLT variation, which is different for low and high Kp conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for Kp≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity. An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (Kp<3 and Kp≥3. In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to auroral arcs as a result of ionosphere-magnetosphere coupling, as discussed by Aikio et al. (2004 In

Safety and injury profile of conducted electrical weapons used by law enforcement officers against criminal suspects.

Science.gov (United States)

Bozeman, William P; Hauda, William E; Heck, Joseph J; Graham, Derrel D; Martin, Brian P; Winslow, James E

2009-04-01

Conducted electrical weapons such as the Taser are commonly used by law enforcement agencies. The safety of these weapons has been the subject of scrutiny and controversy; previous controlled studies in animals and healthy humans may not accurately reflect the risks of conducted electrical weapons used in actual conditions. We seek to determine the safety and injury profile of conducted electrical weapons used against criminal suspects in a field setting. This prospective, multicenter, observational trial tracked a consecutive case series of all conducted electrical weapon uses against criminal suspects at 6 US law enforcement agencies. Mandatory review of each conducted electrical weapon use incorporated physician review of police and medical records. Injuries were classified as mild, moderate, or severe according to a priori definitions. The primary outcome was a composite of moderate and severe injuries, termed significant injuries. Conducted electrical weapons were used against 1,201 subjects during 36 months. One thousand one hundred twenty-five subjects (94%) were men; the median age was 30 years (range 13 to 80 years). Mild or no injuries were observed after conducted electrical weapon use in 1,198 subjects (99.75%; 95% confidence interval 99.3% to 99.9%). Of mild injuries, 83% were superficial puncture wounds from conducted electrical weapon probes. Significant injuries occurred in 3 subjects (0.25%; 95% confidence interval 0.07% to 0.7%), including 2 intracranial injuries from falls and 1 case of rhabdomyolysis. Two subjects died in police custody; medical examiners did not find conducted electrical weapon use to be causal or contributory in either case. To our knowledge, these findings represent the first large, independent, multicenter study of conducted electrical weapon injury epidemiology and suggest that more than 99% of subjects do not experience significant injuries after conducted electrical weapon use.

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

Science.gov (United States)

Zheng, Yaoyang; Shimada, Kunio

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

Electric Double-Layer Interaction between Dissimilar Charge-Conserved Conducting Plates.

Science.gov (United States)

Chan, Derek Y C

2015-09-15

Small metallic particles used in forming nanostructured to impart novel optical, catalytic, or tribo-rheological can be modeled as conducting particles with equipotential surfaces that carry a net surface charge. The value of the surface potential will vary with the separation between interacting particles, and in the absence of charge-transfer or electrochemical reactions across the particle surface, the total charge of each particle must also remain constant. These two physical conditions require the electrostatic boundary condition for metallic nanoparticles to satisfy an equipotential whole-of-particle charge conservation constraint that has not been studied previously. This constraint gives rise to a global charge conserved constant potential boundary condition that results in multibody effects in the electric double-layer interaction that are either absent or are very small in the familiar constant potential or constant charge or surface electrochemical equilibrium condition.

D.C. electrical conductivity measurements on ADP single crystals ...

Indian Academy of Sciences (India)

Unknown

Impurity added ADP crystals; density; electrical conductivity measurements. 1. Introduction ... determined by the intrinsic defects caused by thermal fluctuations in the ... beaker (corning glass vessel) and allowed to equilibrate at the desired ...

Effect of neutron flux on the frequency dependencies of electrical conductivity of silicon nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Huseynov, E.; Garibli, A., E-mail: elchin.huse@yahoo.com [National Nuclear Research Center, Department of Nanotechnology and Radiation Material Science, 1073, Inshaatchilar pr. 4, Baku (Azerbaijan)

2016-11-01

It has been reviewed the frequency dependencies of electrical conductivity of nanoparticles affected by neutron flux at different times and initial state, at various constant temperatures such as 100, 200, 300 and 400 K. Measurements have been carried out at each temperature at the different 97 values of frequency in the 1 Hz - 1 MHz range. From interdependence between real and imaginary parts of electrical conductivity it has been determined the type of conductivity. Moreover, in the work it is given the mechanism of electrical conductivity according to the obtained results. (Author)

Mantle electrical conductivity profile of Niger delta region

Indian Academy of Sciences (India)

The mantle electrical conductivity-depth profile of the Niger delta region in Nigeria has been determined using solar quiet day ionospheric current (Sq).The magnetometer data obtained in 2010 from geomagnetic stations installed in Lagos by magnetic dataset (MAGDAS) in 2008 and data from magnetometers installed in ...

Atlas of total body radionuclide imaging. Volume I and II

International Nuclear Information System (INIS)

Fordham, E.W.; Ali, A.; Turner, D.A.; Charters, J.

1982-01-01

This two-volume work on total body imaging may well be regarded by future historians of nuclear medicine as representing the high points in the art of total body imaging in clinical nuclear medicine. With regard to information content and volume, it is the largest collection of well-interpreted, beautifully reproduced, total body images available to date. The primary goal of this atlas is to demonstrate patterns of abnormality in both typical and less typical variations. This goal is accomplished with many well-described examples of technical artifacts, of normal variants, of common and of rare diseases, and of pitfalls in interpretations. Volume I is entirely dedicated to skeletal imaging with Tc-99m labeled phosphates or phosphonates. The volume is divided into 22 chapters, which include chapters on methodology and instrumentation, chapters on the important bone diseases and other topics such as a treatise on false-negative and false-positive scans, and soft tissue and urinary tract abnormalities recognizable on bone scintigrams

Optical transparency and electrical conductivity of nonstoichiometric ultrathin InxOy films

International Nuclear Information System (INIS)

Joseph, Shay; Berger, Shlomo

2011-01-01

The effect of thickness and composition on the electrical conductivity and optical transparency, mainly in the infrared, of ultrathin In x O y films was studied. In x O y films 35-470 A thick with oxygen atomic fractions of ∼0.3 and ∼0.5 were prepared via dc magnetron sputtering. All films were polycrystalline, consisting of only the cubic bixbiyte phase of In 2 O 3 . The average grain size of the films increased from 30 to 95 nm as the film thickness increased. The weak dependence of the electrical conductivity on the frequency and the low activation energies for conduction, a few hundredths of an eV, provided an indication that free band conduction was the primary electrical conduction mechanism in the case of all ultrathin In x O y films. It was found that introducing a high degree of nonstoichiometry in the form of oxygen deficiency did not help improve the electrical conductivity, since not all vacancies contributed two free electrons for conduction and due to impurity scattering. The optical nature of these films, studied mainly by ellipsometry, was found to be dependent on the film's composition and thickness. In the infrared, the dielectric function of all In x O y films was consistent with the Drude model, inferring that the transparency loss in this region was a result of free charge carriers. In the visible however, In x O y films under 170 A, which had an oxygen atomic fraction of ∼0.5, were modeled by extending the Drude model to the shorter wavelengths. Films over 170 A, with the same composition, were modeled using the Cauchy dispersion model, meaning that no absorption was measured. These results indicate that, optically, under specific compositions, ultrathin In x O y films undergo a transition from metalliclike behavior to dielectric behavior with increasing film thickness. Using a figure of merit approach, it was determined that a nonstoichiometric 230 A thick In x O y film, with an oxygen atomic fraction of ∼0.3, had the best combination

Anelastic spherical dynamos with radially variable electrical conductivity

Science.gov (United States)

Dietrich, W.; Jones, C. A.

2018-05-01

A series of numerical simulations of the dynamo process operating inside gas giant planets has been performed. We use an anelastic, fully nonlinear, three-dimensional, benchmarked MHD code to evolve the flow, entropy and magnetic field. Our models take into account the varying electrical conductivity, high in the ionised metallic hydrogen region, low in the molecular outer region. Our suite of electrical conductivity profiles ranges from Jupiter-like, where the outer hydrodynamic region is quite thin, to Saturn-like, where there is a thick non-conducting shell. The rapid rotation leads to the formation of two distinct dynamical regimes which are separated by a magnetic tangent cylinder - mTC. Outside the mTC there are strong zonal flows, where Reynolds stress balances turbulent viscosity, but inside the mTC Lorentz force reduces the zonal flow. The dynamic interaction between both regions induces meridional circulation. We find a rich diversity of magnetic field morphologies. There are Jupiter-like steady dipolar fields, and a belt of quadrupolar dominated dynamos spanning the range of models between Jupiter-like and Saturn-like conductivity profiles. This diversity may be linked to the appearance of reversed sign helicity in the metallic regions of our dynamos. With Saturn-like conductivity profiles we find models with dipolar magnetic fields, whose axisymmetric components resemble those of Saturn, and which oscillate on a very long time-scale. However, the non-axisymmetric field components of our models are at least ten times larger than those of Saturn, possibly due to the absence of any stably stratified layer.

The Electronic Thermal Conductivity of Graphene.

Science.gov (United States)

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

2016-04-13

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

Thermoelectric power and electrical conductivity of strontium-doped lanthanum manganite

DEFF Research Database (Denmark)

Ahlgren, E.O.; Poulsen, F.W.

1996-01-01

Thermoelectric power and electrical conductivity of pure and 5, 10 and 20% strontium-doped lanthanum manganite are determined as function of temperature in air and of P-O2 at 1000 degrees C. At high temperatures the thermoelectric power is negative. Both thermoelectric power and conductivity...

Fabrication and characterization of stearic acid/polyaniline composite with electrical conductivity as phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Wang, Yi; Ji, Hui; Shi, Huan; Zhang, Ting; Xia, TianDong

2015-01-01

Highlights: • Stearic acid/polyaniline composite PCM with electrical conductivity was fabricated. • Stearic acid acted as thermal energy storage media and doping acid. • Latent heats of SA/PANI are as high as the same type composites. • Improved electrical conductivity of capsules is 0.7042 S cm −1 . - Abstract: This paper presents the experimental investigation on the thermal properties and electrical conductivity of the new microencapsulated phase change material by entrapping of stearic acid (SA) into PANI (polyaniline) shell through self-assembly method. Experimental results reveal that PANI nuclei grew on the surface of SA, and then copied its original morphological structure and finally exhibited peony flower-like morphology. The two components have good compatibility and have no chemical reaction both in the process of fabrication and subsequent use, while hydrogen bondings between the imino groups and carboxyl groups exist. The maximum mass fraction of stearic acid loaded in SA/PANI is determined as high as 62.1 wt% without seepage of melted SA from capsules. Due to the secondary doping with carboxyl group, the composite phase change material embedded with SA exhibits improved electrical conductivity from 0.3968 S cm −1 to 0.7042 S cm −1 when compared to PANI. The phase change temperatures and latent heats of SA/PANI are measured to be 55.6 °C and 113.02 J/g for melting and, 50.8 °C and 112.58 J/g for freezing, respectively. TG analysis test revealed that the prepared SA/PANI composite PCM has high thermal durability in working temperature range. Moreover, the results of DSC, FT-IR, TG, conductivity investigation and thermal cycling test are all show that the thermal reliability and electrical conductivity of the SA/APNI have imperceptible changes. In total, the additional electrical conductivity, high heat storage potential and good thermal reliability and stability facilitated SA/PANI to be considered as a viable candidate for thermal

Marrow toxicity of fractionated vs. single dose total body irradiation is identical in a canine model

International Nuclear Information System (INIS)

Storb, R.; Raff, R.F.; Graham, T.; Appelbaum, F.R.; Deeg, H.J.; Schuening, F.G.; Shulman, H.; Pepe, M.

1993-01-01

The authors explored in dogs the marrow toxicity of single dose total body irradiation delivered from two opposing 60 Co sources at a rate of 10 cGy/min and compared results to those seen with total body irradiation administered in 100 cGy fractions with minimum interfraction intervals of 6 hr. Dogs were not given marrow transplants. They found that 200 cGy single dose total body irradiation was sublethal, with 12 of 13 dogs showing hematopoietic recovery and survival. Seven of 21 dogs given 300 cGy single dose total body irradiation survived compared to 6 of 10 dogs given 300 cGy fractionated total body irradiation. One of 28 dogs given 400 cGy single dose total body irradiation survived compared to none of six given fractionated radiation. With granulocyte colony stimulating factor (GCSF) administered from day 0-21 after 400 cGy total body irradiation, most dogs survived with hematological recovery. Because of the almost uniform success with GCSF after 400 cGy single dose total body irradiation, a study of GCSF after 400 cGy fractionated total body irradiation was deemed not to be informative and, thus, not carried out. Additional comparisons between single dose and fractionated total body irradiation were carried out with GCSF administered after 500 and 600 cGy of total body irradiation. As with lower doses of total body irradiation, no significant survival differences were seen between the two modes of total body irradiation, and only 3 of 26 dogs studied survived with complete hematological recovery. Overall, therefore, survival among dogs given single dose total body irradiation was not different from that of dogs given fractionated total body irradiation (p = .67). Similarly, the slopes of the postirradiation declines of granulocyte and platelet counts and the rates of their recovery in surviving dogs given equal total doses of single versus fractionated total body irradiation were indistinguishable. 24 refs., 3 figs., 2 tabs

Electrical conductivity measurements on gel grown KDP crystals ...

Indian Academy of Sciences (India)

Impurity added KDP crystals; gel method; electrical conductivity; activation energy. 1. Introduction. Potassium dihydrogen ... phate [(NH4)2SO4] along with double distilled water and ethyl alcohol were used. KDP was added with .... in the vicinity of electrodes or chemical changes in layers close to electrodes (Bunget and ...

Gigapixel photography for skin cancer surveillance: a novel alternative to total-body photography.

Science.gov (United States)

Mikailov, Anar; Blechman, Adam

2013-11-01

There is substantial evidence supporting the use of cutaneous imaging in combination with standard total-body skin examinations for early detection and treatment of melanoma. In the last 2 decades, total-body photography (TBP) has been widely used in combination with standard total-body skin examinations for active skin cancer surveillance with proven clinical utility; however, the groundbreaking image detail provided by gigapixel photography (GP) could improve dermatologists' ability to monitor suspicious lesions and therefore could serve a critical role in supplementing traditional total-body skin examinations for skin cancer surveillance. Although it has been successfully implemented in other fields, future studies are required to determine the effectiveness of GP in dermatology.

Electrical conductivity of uranium-antimony oxide catalysts

International Nuclear Information System (INIS)

Golunski, S.E.; Nevell, T.G.; Hucknall, D.J.

1985-01-01

The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO 5 have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb 3 O 10 together with small proportions of Sb 2 O 4 and USbO 5 ) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO 5 . Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO 5 in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation. (author)

Electrical conductivity of uranium-antimony oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Golunski, S.E.; Nevell, T.G. (Portsmouth Polytechnic (UK)); Hucknall, D.J. (Southampton Univ. (UK). Dept. of Chemistry)

1985-05-01

The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO/sub 5/ have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb/sub 3/O/sub 10/ together with small proportions of Sb/sub 2/O/sub 4/ and USbO/sub 5/) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO/sub 5/. Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO/sub 5/ in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation.

Effect of sodium adsorption ratio and electric conductivity of the ...

African Journals Online (AJOL)

Infiltration measurements using a double-ring infiltrometer were conducted on a sandy-loam soil located in Saudi Arabia. The measurements were performed for an undisturbed soil. The effect of sodium adsorption ratio (SAR) and electric conductivity (EC) of the applied water on infiltration rate was examined. The infiltration ...

Investigations on electrical conductivity and dielectric properties of Na doped ZnO synthesized from sol gel method

Energy Technology Data Exchange (ETDEWEB)

Tabib, Asma; Sdiri, Nasr [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University Tunis El Manar, Tunis 2092 (Tunisia); Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia)

2015-02-15

Highlights: • ZnO nanoparticles doped with Na were prepared from sol-gel method. • Electric conductivity and dielectric properties were investigated. • The ZnO conductivity is estimated to be of p-type for critical Na doping of 1.5% at. - Abstract: Na doped ZnO nanoparticles (NPs) were elaborated by sol gel technique. The X-ray diffraction patterns show that the peaks are indexed to the hexagonal structure without any trace of an extra phase. Electric and dielectric properties were investigated using complex impedance spectroscopy. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). The contribution of grain boundary resistance to the total resistance of the system is remarkable. The AC conductivity increases with temperature following the Arrhenius law, with single apparent activation energy for conduction process. The frequency dependence of the electric conductivity follows a simple power law behavior, in according to relation σ{sub AC}(ω) = σ(0) + A ω{sup s}, where s is smaller than 1. The analysis of dc conductivity indicates that the conduction is ionic in nature. The study of its variation, at fixed temperature, with Na content shows sharp decrease which is explained by the formation of Na{sub Zn} acceptor. It was found that the dc conductivity reaches its minimum value for critical Na concentration of 1.5% at which the conductivity is estimated to be of p-type. Impedance and modulus study reveals the temperature dependent non-Debye type relaxation phenomenon. Dielectric studies revealed a promising dielectric properties (relatively high ε′ at low frequencies and low loss at high frequencies). In the low-frequency region, the values of M′ tends to zero suggesting negligible or absent electrode polarization phenomenon. The frequency dependent maxima in the imaginary modulus are found to obey to Arrhenius law.

Evaluation of Electrical and Thermal Conductivity of Polymeric ...

African Journals Online (AJOL)

PROF HORSFALL

ABSTRACT: This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with ...

Polypyrrole-chitosan conductive biomaterial synchronizes cardiomyocyte contraction and improves myocardial electrical impulse propagation.

Science.gov (United States)

Cui, Zhi; Ni, Nathan C; Wu, Jun; Du, Guo-Qing; He, Sheng; Yau, Terrence M; Weisel, Richard D; Sung, Hsing-Wen; Li, Ren-Ke

2018-01-01

Background: The post-myocardial infarction (MI) scar interrupts electrical impulse propagation and delays regional contraction, which contributes to ventricular dysfunction. We investigated the potential of an injectable conductive biomaterial to restore scar tissue conductivity and re-establish synchronous ventricular contraction. Methods: A conductive biomaterial was generated by conjugating conductive polypyrrole (PPY) onto chitosan (CHI) backbones. Trypan blue staining of neonatal rat cardiomyocytes (CMs) cultured on biomaterials was used to evaluate the biocompatibility of the conductive biomaterials. Ca 2+ imaging was used to visualize beating CMs. A cryoablation injury rat model was used to investigate the ability of PPY:CHI to improve cardiac electrical propagation in the injured heart in vivo . Electromyography was used to evaluate conductivity of scar tissue ex vivo . Results: Cell survival and morphology were similar between cells cultured on biomaterials-coated and uncoated-control dishes. PPY:CHI established synchronous contraction of two distinct clusters of spontaneously-beating CMs. Intramyocardial PPY:CHI injection into the cryoablation-induced injured region improved electrical impulse propagation across the scarred tissue and decreased the QRS interval, whereas saline- or CHI-injected hearts continued to have delayed propagation patterns and significantly reduced conduction velocity compared to healthy controls. Ex vivo evaluation found that scar tissue from PPY:CHI-treated rat hearts had higher signal amplitude compared to those from saline- or CHI-treated rat heart tissue. Conclusions: The PPY:CHI biomaterial is electrically conductive, biocompatible and injectable. It improved synchronous contraction between physically separated beating CM clusters in vitro . Intra-myocardial injection of PPY:CHI following cardiac injury improved electrical impulse propagation of scar tissue in vivo .

Electrical conductivity of short carbon fibers and carbon black-reinforced chloroprene rubber

International Nuclear Information System (INIS)

Khoshniat, A. R.; MirAli, M.; Hemmati, M.; Afshar Taromi, F.; Katbab, A.

2002-01-01

Elastomers and plastics are intrinsically insulating materials, but by addition of some conductive particles such as conductive carbon black, carbon fibers and metals, they can change to conductive form. Conductivity of these composites are due to formation of the lattices of conductive filler particles in polymer chains. In this report, conductivity of chloroprene rubber filled with carbon black and carbon fibers as a function of temperature and pressure are studied. Electrical conductivity of chloroprene in a function of temperature and pressure are studied. Electrical conductivity of chloroprene in the presence of carbon black with proper mixing conditions increases to the conductivity level of semiconductors and even in the presence of carbon fibers it increases to the level of a conductor material. Meanwhile, the sensitivity of this compound to heat and pressure rises. Thus these composites have found various applications in the manufacture of heat and pressure sensitive sensors

Statistical properties of Joule heating rate, electric field and conductances at high latitudes

Directory of Open Access Journals (Sweden)

A. T. Aikio

2009-07-01

Full Text Available Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox and from similar sunspot conditions (about 1.5 years before the sunspot minimum providing an excellent set of data to study the MLT and K_p dependence of parameters with high temporal and spatial resolution.

All the parameters show a clear MLT variation, which is different for low and high K_p conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for K_p≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity.

An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (K_p<3 and K_p≥3. In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to

Electrical properties and conduction mechanisms of Ru-based thick-film (cermet) resistors

International Nuclear Information System (INIS)

Pike, G.E.; Seager, C.H.

1977-01-01

This paper presents an experimental study of the electrical conduction mechanisms in thick-film (cermet) resistor. The resistors were made from one custom and three commercially formulated inks with sheet resistivities ranging from 10 2 to 10 6 Ω/D 7 Alembertian in decade increments. Their microstructure and composition have been examined using optical and scanning electron microscopy, electron microprobe analysis, x-ray diffraction, and various chemical analyses. This portion of our study shows that the resistors are heterogeneous mixtures of metallic metal oxide particles (approx.4 x 10 -5 cm in diameter) and a lead silicate glass. The metal oxide particles are ruthenium containing pyrochlores, and are joined to form a continuous three-dimensional network of chain segments. The principal experimental work reported here is an extensive study of the electrical transport properties of the resistors. The temperature dependence of conductance has been measured from 1.2 to 400 K, and two features common to all resistors are found. There is a pronounced decrease in conductance at low temperatures and a shallow maximum at several hundred Kelvin. Within the same range of temperatures the reversible conductance as a function of electric field from 0 to 28 kV/cm has been studied. The resistors are non-Ohmic at all temperatures, but particularly at cryogenic temperatures for low fields. At higher fields the conductance shows a linear variation with electric field. The thick-film resistors are found to have a small dielectric constant and a (nearly) frequency-independent conductance from dc to 50 MHz. The magnetoresistance to 100 kG, the Hall mobility, and the Seebeck coefficient of most of the resistors have been measured and discovered to be quite small. Many of the electrical transport properties have also been determined for the metal oxide particles which were extracted from the fired resistors

Nanoionics phenomenon in proton-conducting oxide: Effect of dispersion of nanosize platinum particles on electrical conduction properties

Directory of Open Access Journals (Sweden)

Hiroshige Matsumoto et al

2007-01-01

Full Text Available High-temperature proton conductors are oxides in which low-valence cations are doped as electron acceptors; the incorporation of water molecules into the oxides results in the formation of protonic defects that act as charge carriers. Since the protons thus formed are in equilibrium with other electronic defects, electrons and holes, the oxides possibly have different proton-conduction properties at and near boundaries when they are in contact with another phase. In this paper, we present our recent experimental observation of a marked change in the electrical properties of a proton conductor upon the dispersal of fine platinum particles in the oxide. First, the material shows extremely low electrical conductivity in comparison with the original proton-conducting perovskite. Second, there was a threshold amount of platinum at which such a drop in conductivity occurred. A percolation model is employed to explain these experimental results; the fine platinum particles dispersed in the proton-conducting oxide wears highly resistive skin that is formed due to shifts in defect equilibriums, which prevents ionic/electronic conduction. The experiments suggest that the ion-conducting properties of oxides can be varied by introducing interfaces at a certain density; nanoionics is a key to yielding enhanced and/or controlled ionic conduction in solids.

Superposition approach for description of electrical conductivity in sheared MWNT/polycarbonate melts

Directory of Open Access Journals (Sweden)

M. Saphiannikova

2012-06-01

Full Text Available The theoretical description of electrical properties of polymer melts, filled with attractively interacting conductive particles, represents a great challenge. Such filler particles tend to build a network-like structure which is very fragile and can be easily broken in a shear flow with shear rates of about 1 s–1. In this study, measured shear-induced changes in electrical conductivity of polymer composites are described using a superposition approach, in which the filler particles are separated into a highly conductive percolating and low conductive non-percolating phases. The latter is represented by separated well-dispersed filler particles. It is assumed that these phases determine the effective electrical properties of composites through a type of mixing rule involving the phase volume fractions. The conductivity of the percolating phase is described with the help of classical percolation theory, while the conductivity of non-percolating phase is given by the matrix conductivity enhanced by the presence of separate filler particles. The percolation theory is coupled with a kinetic equation for a scalar structural parameter which describes the current state of filler network under particular flow conditions. The superposition approach is applied to transient shear experiments carried out on polycarbonate composites filled with multi-wall carbon nanotubes.

Testing the equation of state and electrical conductivity of copper by the electrical wire explosion in air: Experiment and magnetohydrodynamic simulation

International Nuclear Information System (INIS)

Barysevich, A. E.; Cherkas, S. L.

2011-01-01

We perform experiments on testing the equations of state and electrical conductivity of copper in three different regimes of copper wire electrical explosion, when the inserted energy (i) is slightly exceeded, (ii) is approximately equal, and (iii) is substantially exceeded the energy needed for the wire complete evaporation. Magnetohydrodynamic simulation is performed. The results predicted by the two different equations of state are compared with the experiment. Empirical expression for the copper electrical conductivity is presented. Parameters in this expression is fit on every of two equations of state. Map of copper conductivity is plotted.

Total and regional body-composition changes in early postmenopausal women

DEFF Research Database (Denmark)

Wang, Q; Hassager, C; Ravn, Pernille

1994-01-01

Total and regional body composition were measured in 373 early postmenopausal women aged 49-60 y by dual-energy x-ray absorptiometry to evaluate whether the changes in body composition in the early postmenopausal years are related to menopause itself or merely to age. Both fat mass and fat...

The variation of electrical conductivity with temperature for Cu ...

African Journals Online (AJOL)

ZnS) alloy with temperature has been investigated. The electrical conductivity of the samples increases with temperature and obeys the Arrhenius relation, δ= δ° exp (-Eg/2kT) which is characteristic of semiconductors. The energy gaps ...

In vivo measurement of total body carbon using 238Pu/Be neutron sources

International Nuclear Information System (INIS)

Sutcliffe, J.F.; Mitra, S.; Hill, G.L.

1990-01-01

Total body carbon has been measured by in vivo neutron activation analysis (IVNAA) in 278 surgical gastroenterological patients and 29 normal volunteers. This is based on the inelastic scattering reaction { 12 C(n,n') 12 C*} for neutrons with energy above 4.8MeV, producing 4.43 MeV gamma rays. Since only part of the body is scanned, total body carbon is estimated as the ratio of the gamma ray emission from carbon to the emission from hydrogen, using hydrogen as the internal standard. The precision of the estimate is ±1.6kg for a whole body dose of 0.3mSv. There is a significant difference between the estimates of total body water from IVNAA measurements of carbon and nitrogen and measurements of body water in these subjects by tritium dilution (t=3.1, p < 0.005). (author)

Analysis of in-situ electrical conductivity data from the HFIR TRIST-ER1 experiment

International Nuclear Information System (INIS)

Zinkle, S.J.; Snead, L.L.; Shikama, T.

1997-01-01

The current vs. applied voltage data generated from the HFIR TRIST-ER1 experiment have been analyzed to determine the electrical conductivity of the 15 aluminum oxide specimens and the MgO-insulated electrical cables as a function of irradiation dose. With the exception of the 0.05%Cr-doped sapphire (ruby) specimen, the electrical conductivity of the alumina specimens remained at the expected radiation induced conductivity (RIC) level of -6 S/m during full-power reactor irradiation (10-16 kGy/s) at 450-500 degrees C up to a maximum dose of ∼3 dpa. The ruby specimen showed a rapid initial increase in conductivity to ∼2 x 10 -4 S/m after ∼0.1 dpa, followed by a gradual decrease to -6 S/m after 2 dpa. Nonohmic electrical behavior was observed in all of the specimens, and was attributed to preferential attraction of ionized electrons in the capsule gas to the unshielded low-side bare electrical leads emanating from the subcapsules. The electrical conductivity was determined from the slope of the specimen current vs. voltage curve at negative voltages, where the gas ionization effect was minimized. Dielectric breakdown tests performed on unirradiated mineral-insulated coaxial cables identical to those used in the high voltage coaxial cables during the 3-month irradiation is attributable to thermal dielectric breakdown in the glass seals at the end of the cables, as opposed to a radiation-induced electrical degradation (RIED) effect

Electrical conductivity of sandstone, limestone, and granite

Energy Technology Data Exchange (ETDEWEB)

Duba, A.; Piwinskii, A.J.; Santor, M.; Weed, H.C.

1978-01-01

The electrical conductivity of cylindrical cores of Westerly granite, Indiana limestone and Nugget, St Peter and Kayenta sandstones was measured at about 25/sup 0/C in vacuo, in air, and after saturation in distilled water, tap water, and 0.1 M NaCl solution. The three-electrode technique with a guard ring and the two-electrode technique without a guard ring were used. Core aspect ratio over the range of 2.00 to 0.25, as well as frequency over the range of 50 Hz to 10 kHz, influences the conductivity of all rocks, especially those measured in vacuo. Measurements from water-saturated samples using a guard ring are not appreciably different from those obtained without a guard ring. The conductivity of rocks saturated in 0.1 M NaCl solution changes least with a change in aspect ratio; for these rocks a linear relationship, known as Archie's Law, exists between log porosity and log conductivity. No simple correlation was found between those factors in rocks saturated with tap or distilled water. Thus, it appears Archie's Law is of questionable value for correlating laboratory data from rocks saturated with low-conductivity fluids.

Electrical conduction in 7 nm wires constructed on λ-DNA

International Nuclear Information System (INIS)

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

2006-01-01

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

In situ electrical conductivity measurements of H{sub 2}O under static pressure up to 28 GPa

Energy Technology Data Exchange (ETDEWEB)

Liu, Bao, E-mail: liubao@nedu.edu.cn [Institute of Materials Physics, College of Science, Northeast Dianli University, Jilin 132012 (China); State Key Laboratory of Superhard Materials, Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China); Gao, Yang [State Key Laboratory of Superhard Materials, Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China); Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409 (United States); Han, Yonghao [State Key Laboratory of Superhard Materials, Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China); Ma, Yanzhang [Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409 (United States); Gao, Chunxiao, E-mail: cc060109@qq.com [State Key Laboratory of Superhard Materials, Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012 (China)

2016-08-26

Highlights: • We conduct in situ electrical conductivity measurements on water in a diamond anvil cell (DAC) under high pressure up to 28 GPa and study the electrical transport properties of water and ices. • In liquid state, the increasing rate of electrical conductivity with pressure is slower than that obtained in shock-waves measurements. • In solid phase, the relationship between electrical conductivity and pressure is discontinuous, which is corresponding to phase transformation from ice VIII to ice VII. • The difference in electrical conductivity of VI, VII, and VIII may associate with different orientational ordering in these ices. • The electrical conduction in these ices is dominated by already existing ions and Bjerrum defects, which play an important role in electrical transport properties of ices. - Abstract: The in situ electrical conductivity measurements on water in both solid state and liquid state were performed under pressure up to 28 GPa and temperature from 77 K to 300 K using a microcircuit fabricated on a diamond anvil cell (DAC). Water chemically ionization mainly contributes to electrical conduction in liquid state, which is in accord with the results obtained under dynamic pressure. Energy band theory of liquid water was used to understand effect of static pressure on electrical conduction of water. The electric conductivity of H{sub 2}O decreased discontinuously by four orders of magnitude at 0.7–0.96 GPa, indicating water frozen at this P–T condition. Correspondingly, the conduction of H{sub 2}O in solid state is determined by arrangement and bending of H-bond in ice VI and ice VII. Based on Jaccard theory, we have concluded that the charge carriers of ice are already existing ions and Bjerrum defects.

Electric conductivity and bootstrap current in tokamak

International Nuclear Information System (INIS)

Mao Jianshan; Wang Maoquan

1996-12-01

A modified Ohm's law for the electric conductivity calculation is presented, where the modified ohmic current can be compensated by the bootstrap current. A comparison of TEXT tokamak experiment with the theories shows that the modified Ohm's law is a more close approximation to the tokamak experiments than the classical and neoclassical theories and can not lead to the absurd result of Z eff <1, and the extended neoclassical theory would be not necessary. (3 figs.)

Measurements of the total-body potassium contents. Application of reference value with the whole-body counter

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Tetsuo [Chiba Univ. (Japan). Inst. for Training Radiological Technicians; Saegusa, Kenji; Arimizu, Noboru; Kuniyasu, Yoshio; Itoh, Hisao

2001-08-01

The total-body potassium contents were measured in 405 healthy volunteers and 186 patients with whole body counter in Chiba University Hospital. The total-body potassium contents was expressed by the reference value (R value). The R value was calculated as measured potassium contents (g) divided by the body surface area (m{sup 2}) and adjusted by age and sex of healthy persons. The R value was 100.65{+-}9.22% in 405 healthy volunteers. Those of each disease were as follows: liver cirrhosis; 94.24{+-}11.22%, chronic hepatitis; 95.74{+-}11.24%, hyperthyroidism; 99.37{+-}10.8%, periodic paralysis; 82.0{+-}9.01%, Barter's syndrome; 93.99{+-}9.86%, myasthenia gravis; 97.34{+-}6.42% and hypo-potassemia; 90.64{+-}11.76%, respectively. The R values of other diseases such as uterine cancer, breast cancer, anemia, hypertension were 97.78{+-}11.5%, 99.22{+-}8.88%, 96.64{+-}12.73%, 98.5{+-}9.63% respectively. Fourteen patients showed especially lower R values under 75%. These were 1 liver cirrhosis, 3 hypertension, 1 diabetes mellitus, 3 hypo-potassemia, 1 periodic paralysis, 2 Barter's syndrome, 2 chemical poisoning, and 1 breast cancer. Follow-up study was performed in some patients with the lower R values. The result of follow-up study showed that there was a relationship between improvement of symptoms and increase of total body potassium contents. (author)

Measurements of the total-body potassium contents. Application of reference value with the whole-body counter

International Nuclear Information System (INIS)

Yamamoto, Tetsuo; Saegusa, Kenji; Arimizu, Noboru; Kuniyasu, Yoshio; Itoh, Hisao

2001-01-01

The total-body potassium contents were measured in 405 healthy volunteers and 186 patients with whole body counter in Chiba University Hospital. The total-body potassium contents was expressed by the reference value (R value). The R value was calculated as measured potassium contents (g) divided by the body surface area (m 2 ) and adjusted by age and sex of healthy persons. The R value was 100.65±9.22% in 405 healthy volunteers. Those of each disease were as follows: liver cirrhosis; 94.24±11.22%, chronic hepatitis; 95.74±11.24%, hyperthyroidism; 99.37±10.8%, periodic paralysis; 82.0±9.01%, Barter's syndrome; 93.99±9.86%, myasthenia gravis; 97.34±6.42% and hypo-potassemia; 90.64±11.76%, respectively. The R values of other diseases such as uterine cancer, breast cancer, anemia, hypertension were 97.78±11.5%, 99.22±8.88%, 96.64±12.73%, 98.5±9.63% respectively. Fourteen patients showed especially lower R values under 75%. These were 1 liver cirrhosis, 3 hypertension, 1 diabetes mellitus, 3 hypo-potassemia, 1 periodic paralysis, 2 Barter's syndrome, 2 chemical poisoning, and 1 breast cancer. Follow-up study was performed in some patients with the lower R values. The result of follow-up study showed that there was a relationship between improvement of symptoms and increase of total body potassium contents. (author)

A generative modeling approach to connectivity-Electrical conduction in vascular networks

DEFF Research Database (Denmark)

Hald, Bjørn Olav

2016-01-01

The physiology of biological structures is inherently dynamic and emerges from the interaction and assembly of large collections of small entities. The extent of coupled entities complicates modeling and increases computational load. Here, microvascular networks are used to present a novel...... to synchronize vessel tone across the vast distances within a network. We hypothesize that electrical conduction capacity is delimited by the size of vascular structures and connectivity of the network. Generation and simulation of series of dynamical models of electrical spread within vascular networks...... of different size and composition showed that (1) Conduction is enhanced in models harboring long and thin endothelial cells that couple preferentially along the longitudinal axis. (2) Conduction across a branch point depends on endothelial connectivity between branches. (3) Low connectivity sub...

Electrical conductivity of the nutrient solution and plant density in aeroponic production of seed potato under tropical conditions (winter/spring

Directory of Open Access Journals (Sweden)

Alex Humberto Calori

Full Text Available ABSTRACT The recent introduction in Brazil of production of quality seed potatoes in hydroponic systems, such as aeroponics, demands studies on the nutritional and crop management. Thus, this study evaluated the influence of electrical conductivity of the nutrient solution and plant density on the seed potato minitubers production in aeroponics system. The Agata and Asterix cultivars were produced in a greenhouse under tropical conditions (winter/spring. The experimental design was a randomized block in a split-split plot design. The plot consisted of 4 electrical conductivities of the nutrient solution (1.0; 2.0; 3.0; and 4.0 dS∙m−1; the subplot, of 4 plant densities (25; 44; 66; and 100 plants∙m−2; and the subsubplot, of the 2 potato cultivars (Ágata and Asterix, totaling 4 blocks. The 2.2 and 2.1 dS∙m−1 electrical conductivities yielded the highest productivity of seed potato minitubers, for Ágata and Asterix cultivars, respectively, regardless of plant density. For both cultivars, the highest yield was observed for the 100 plants∙m−2 density.

Measurement of total body radioactivity in man

International Nuclear Information System (INIS)

Naversten, Y.

1982-01-01

Techniques for the determination of whole-body radioactivity in man using uncollimated NaI(Tl) detectors have been studied. Geometrical effects and photon attenuation effects due to the different shapes of humans as well as due to varying in-vivo radioactivity distributions have been evaluated particularly for scanning-bed geometries and the chair geometry. Theoretically it is shown that the attenuation effects are generally dominating, for full-energy-peak pulse-range methods. For the application in radiation protection a cheap and simple chair-geometry unit has been constructed and used at various places distantly from the home-laboratory, for studies of body activity of Cs-137 in northern Sweden. High body activities were found particularly in reindeer-breeding Lapps. The elimination rate of Cs-137 in man was studied in the stationary whole-body counter in Lund as well as with the field-system. For the study of the performances at low and high photon energies clinical applications of methods for gastro-intestinal absorption of vitamin B12 (Co-57; 122 keV) and total body potassium determination (K-40; 1.46 MeV, K-42; 1.52 MeV) have been evaluated. Theoretical and experimental results as well as experiences of applications in radiation protection and medicine show that the scanning-bed geometry effectively evens out redistributional effects. For optimum results, however, scatter-energy pulse-ranges rather than full-energy-peak ranges should be used. (Auth.)

Total Body Photography as an Aid to Skin Self-examination: A Patient's Perspective.

Science.gov (United States)

Secker, Lisanne J; Bergman, Wilma; Kukutsch, Nicole A

2016-02-01

Skin self-examination can help patients who are at high risk for developing melanoma to become more involved in their own surveillance and treatment. This study examined the use of total body photography as an aid to skin self-examination from the patients' perspective. A total of 179 individuals at high risk for developing melanoma who had undergone total body photography (60.5% response rate) completed a self-reported questionnaire assessing the frequency of skin self-examination, perceived usefulness of total body photography, and a variety of potential demographic, clinical and psychological factors. Only approximately half of the participants indicated skin self-examination as useful and 78.9% preferred clinical skin examination by a specialist. Finding total body photography useful was associated with having received instructions on how to perform skin self-examination, the use of a (hand)mirror, and confidence to detect changing moles. These findings allow us to develop strategies to further improve patients' self-screening behaviours.

Measurement of temperature, electric conductivity and density of plasma

International Nuclear Information System (INIS)

Vasilevova, I.; Nefedov, A.; Oberman, F.; Urinson, A.

1982-01-01

Three instruments are briefly described developed by the High Temperatures Institute of the USSR Academy of Sciences for the measurement of plasma temperature, electric conductivity and density. The temperature measuring instrument uses as a standard a light source whose temperature may significantly differ from plasma temperature because three light fluxes are compared, namely the flux emitted by the plasma, the flux emitted directly by the standard source, and the flux emitted by the standard source after passage through the plasma. The results of measurement are computer processed. Electric conductivity is measured using a coil placed in a probe which is automatically extended for a time of maximally 0.3 seconds into the plasma stream. The equipment for measuring plasma density consists of a special single-channel monochromator, a temperature gauge, a plasma pressure gauge, and of a computer for processing the results of measurement. (Ha)

Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

Science.gov (United States)

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

2015-07-21

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

Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

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

2017-10-17

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

Osteochondroma after total body irradiation in bone marrow transplant recipients. Report of two cases

International Nuclear Information System (INIS)

Maeda, Go; Yokoyama, Ryohei; Ohtomo, Katsuyuki; Takayama, Jun; Beppu, Yasuo; Fukuma, Hisatoshi; Ohira, Mutsuro

1996-01-01

We present two cases of osteochondroma after total body irradiation in bone marrow recipients, the first in a 6-year-old boy with juvenile chronic myelogenous leukemia and the second in a 13-year-old boy with acute myelogenous leukemia. The patients developed multiple osteochondromas three years and seven years, respectively, after 12 Gy of total body irradiation. Neither had a family history of hereditary multiple osteochondromatosis. A review of the English literature revealed only one report describing five cases of osteochondroma after 12 Gy of total body irradiation in bone marrow transplant recipients. Osteochondroma should be considered as an additional adverse effect of total body irradiation. (author)

Analysis of in-situ electrical conductivity data from the HFIR TRIST-ER1 experiment

Energy Technology Data Exchange (ETDEWEB)

Zinkle, S.J.; Snead, L.L. [Oak Ridge National Lab., TN (United States); Shikama, T. [Tohoku Univ. (Japan)] [and others

1997-08-01

The current vs. applied voltage data generated from the HFIR TRIST-ER1 experiment have been analyzed to determine the electrical conductivity of the 15 aluminum oxide specimens and the MgO-insulated electrical cables as a function of irradiation dose. With the exception of the 0.05%Cr-doped sapphire (ruby) specimen, the electrical conductivity of the alumina specimens remained at the expected radiation induced conductivity (RIC) level of <10{sup -6} S/m during full-power reactor irradiation (10-16 kGy/s) at 450-500{degrees}C up to a maximum dose of {approximately}3 dpa. The ruby specimen showed a rapid initial increase in conductivity to {approximately}2 x 10{sup -4} S/m after {approximately}0.1 dpa, followed by a gradual decrease to <1 x 10{sup -6} S/m after 2 dpa. Nonohmic electrical behavior was observed in all of the specimens, and was attributed to preferential attraction of ionized electrons in the capsule gas to the unshielded low-side bare electrical leads emanating from the subcapsules. The electrical conductivity was determined from the slope of the specimen current vs. voltage curve at negative voltages, where the gas ionization effect was minimized. Dielectric breakdown tests performed on unirradiated mineral-insulated coaxial cables identical to those used in the high voltage coaxial cables during the 3-month irradiation is attributable to thermal dielectric breakdown in the glass seals at the end of the cables, as opposed to a radiation-induced electrical degradation (RIED) effect.

Lightweight magnesium nanocomposites: electrical conductivity of liquid magnesium doped by CoPd nanoparticles

Science.gov (United States)

Yakymovych, Andriy; Slabon, Adam; Plevachuk, Yuriy; Sklyarchuk, Vasyl; Sokoliuk, Bohdan

2018-04-01

The effect of monodisperse bimetallic CoPd NP admixtures on the electrical conductivity of liquid magnesium was studied. Temperature dependence of the electrical conductivity of liquid Mg98(CoPd)2, Mg96(CoPd)4, and Mg92(CoPd)8 alloys was measured in a wide temperature range above the melting point by a four-point method. It was shown that the addition of even small amount of CoPd nanoparticles to liquid Mg has a significant effect on the electrical properties of the melts obtained.

Effect of temperature on electrical conductance of inkjet-printed silver nanoparticle ink during continuous wave laser sintering

International Nuclear Information System (INIS)

Lee, Dae-Geon; Kim, Dong Keun; Moon, Yoon-Jae; Moon, Seung-Jae

2013-01-01

To determine the effect of temperature on the specific electrical conductance of inkjet-printed ink during continuous wave laser sintering, the temperature of the sintered ink was estimated. The ink, which contained 34 wt.% silver nanoparticles with an average size of approximately 50 nm, was inkjet-printed onto a liquid crystal display glass substrate. The printed ink was irradiated with a 532 nm continuous wave laser for 60 s with various laser intensities. During laser irradiation, the in-situ electrical conductance of the sintered ink was measured to estimate the transient thermal conductivity of the ink. The electrical conductance and thermal conductivity of the ink was coupled to obtain the transient temperature by applying the Wiedemann–Franz law to a two-dimensional transient heat conduction equation. The electrical conductance of laser-sintered ink was highly dependent on the sintering temperature of the ink. - Highlights: • The in-situ electrical conductance was measured during the laser sintering process. • Wiedemann–Franz law coupled the electrical conductance with transient temperature. • The transient temperature of the laser-sintered Ag nanoparticle ink was estimated

Electrical regulation of Schwann cells using conductive polypyrrole/chitosan polymers.

Science.gov (United States)

Huang, Jinghui; Hu, Xueyu; Lu, Lei; Ye, Zhengxu; Zhang, Quanyu; Luo, Zhuojing

2010-04-01

Electrical stimulation (ES) can dramatically enhance neurite outgrowth through conductive polymers and accelerate peripheral nerve regeneration in animal models of nerve injury. Therefore, conductive tissue engineering graft in combination with ES is a potential treatment for neural injuries. Conductive tissue engineering graft can be obtained by seeding Schwann cells on conductive scaffold. However, when ES is applied through the conductive scaffold, the impact of ES on Schwann cells has never been investigated. In this study, a biodegradable conductive composite made of conductive polypyrrole (PPy, 2.5%) and biodegradable chitosan (97.5%) was prepared in order to electrically stimulate Schwann cells. The tolerance of Schwann cells to ES was examined by a cell apoptosis assay. The growth of the cells was characterized using DAPI staining and a MTT assay. mRNA and protein levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in Schwann cells were assayed by RT-PCR and Western blotting, and the amount of NGF and BDNF secreted was determined by an ELISA assay. The results showed that the PPy/chitosan membranes supported cell adhesion, spreading, and proliferation with or without ES. Interestingly, ES applied through the PPy/chitosan composite dramatically enhanced the expression and secretion of NGF and BDNF when compared with control cells without ES. These findings highlight for the first time the possibility of enhancing nerve regeneration in conductive scaffolds through ES-increased neurotrophin secretion.

Total body irradiation for children with malignancies

Energy Technology Data Exchange (ETDEWEB)

Sanuki, Eiichi; Maeno, Toshio; Kamata, Rikisaburo; Tanaka, Yoshiaki; Mugishima, Hideo [Nihon Univ., Tokyo (Japan). School of Medicine

1995-12-01

Total body irradiation combined with high dose chemotherapy has been performed just before bone marrow transplantation in 35 children with advanced malignancies, with the object of achieving successful transplantation and improving the prognosis. Simulation was performed as follows: back scatter, flatness, dose accumulation using randophantom and dose distribution using a thermo-luminescence dosimeter and linac-graphy. The standard error of dose distribution was within 10%. In neuroblastoma, of which there were 14 cases in stage IV and one case in stage III, the 5-year survival rate was 55%. In leukemia, of which all cases were in the high-risk group (7 cases of acute lymphoblastic leukemia and 2 of acute myeloblastic leukemia) the 5-year survival rate was 55%. The 5 cases having first remission survived disease-free while the 4 cases having non-first remission died. In malignant lymphoma (6 cases in stage IV and one case in stage III, with bulky mass) the 5-year survival rate was 67%. Four cases with other diagnoses (severe aplastic anemia, and others) all survived. As yet no side effects resulting from total body irradiation have been recognized in our cases, but a longer follow-up period is necessary to observe possible late side effects. (author).

Electrically conductive gold nanoparticle-chitosan thermosensitive hydrogels for cardiac tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Baei, Payam [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of); Cardiovascular Engineering Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); Jalili-Firoozinezhad, Sasan [Department of Biomedicine and Surgery, University Hospital Basel, University of Basel, Hebelstrasse 20, CH-4031 Basel (Switzerland); Department of Bioengineeringand IBB - Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Rajabi-Zeleti, Sareh [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of); Tafazzoli-Shadpour, Mohammad [Cardiovascular Engineering Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); Baharvand, Hossein, E-mail: Baharvand@royaninstitute.org [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of); Department of Developmental Biology, University of Science and Culture, ACECR, Tehran (Iran, Islamic Republic of); Aghdami, Nasser, E-mail: Nasser.Aghdami@royaninstitute.org [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of)

2016-06-01

Injectable hydrogels that resemble electromechanical properties of the myocardium are crucial for cardiac tissue engineering prospects. We have developed a facile approach that uses chitosan (CS) to generate a thermosensitive conductive hydrogel with a highly porous network of interconnected pores. Gold nanoparticles (GNPs) were evenly dispersed throughout the CS matrix in order to provide electrical cues. The gelation response and electrical conductivity of the hydrogel were controlled by different concentrations of GNPs. The CS-GNP hydrogels were seeded with mesenchymal stem cells (MSCs) and cultivated for up to 14 days in the absence of electrical stimulations. CS-GNP scaffolds supported viability, metabolism, migration and proliferation of MSCs along with the development of uniform cellular constructs. Immunohistochemistry for early and mature cardiac markers showed enhanced cardiomyogenic differentiation of MSCs within the CS-GNP compared to the CS matrix alone. The results of this study demonstrate that incorporation of nanoscale electro-conductive GNPs into CS hydrogels enhances the properties of myocardial constructs. These constructs could find utilization for regeneration of other electroactive tissues. - Highlights: • Thermosensitive electro-conductive hydrogels were prepared from CS and GNPs. • Gelation time and conductivity were tuned by varying concentration of GNPs. • CS-2GNP with gelation time of 25.7 min and conductivity of 0.13 S·m{sup −1} was selected for in vitro studies. • CS-2GNP supported active metabolism, migration and proliferation of MSCs. • Expression of cardiac markers increased about two-fold in CS-2GNP compared to CS.

Electrically conductive gold nanoparticle-chitosan thermosensitive hydrogels for cardiac tissue engineering

International Nuclear Information System (INIS)

Baei, Payam; Jalili-Firoozinezhad, Sasan; Rajabi-Zeleti, Sareh; Tafazzoli-Shadpour, Mohammad; Baharvand, Hossein; Aghdami, Nasser

2016-01-01

Injectable hydrogels that resemble electromechanical properties of the myocardium are crucial for cardiac tissue engineering prospects. We have developed a facile approach that uses chitosan (CS) to generate a thermosensitive conductive hydrogel with a highly porous network of interconnected pores. Gold nanoparticles (GNPs) were evenly dispersed throughout the CS matrix in order to provide electrical cues. The gelation response and electrical conductivity of the hydrogel were controlled by different concentrations of GNPs. The CS-GNP hydrogels were seeded with mesenchymal stem cells (MSCs) and cultivated for up to 14 days in the absence of electrical stimulations. CS-GNP scaffolds supported viability, metabolism, migration and proliferation of MSCs along with the development of uniform cellular constructs. Immunohistochemistry for early and mature cardiac markers showed enhanced cardiomyogenic differentiation of MSCs within the CS-GNP compared to the CS matrix alone. The results of this study demonstrate that incorporation of nanoscale electro-conductive GNPs into CS hydrogels enhances the properties of myocardial constructs. These constructs could find utilization for regeneration of other electroactive tissues. - Highlights: • Thermosensitive electro-conductive hydrogels were prepared from CS and GNPs. • Gelation time and conductivity were tuned by varying concentration of GNPs. • CS-2GNP with gelation time of 25.7 min and conductivity of 0.13 S·m"−"1 was selected for in vitro studies. • CS-2GNP supported active metabolism, migration and proliferation of MSCs. • Expression of cardiac markers increased about two-fold in CS-2GNP compared to CS.

Electrical-conductivity measurements of leachates for the rapid assessment of wasteform corrosion resistance

International Nuclear Information System (INIS)

Sales, B.C.; Petek, M.; Boatner, L.A.

1982-01-01

Measurements of the electrical conductivity of leachate solutions as a function of time can be used as an efficient, informative means of evaluation and comparison in the development of nuclear waste forms and in the preliminary analysis of their corrosion resistance in distilled water. Three separate applications of this technique are described in this work. These are: (1) its use in the optimization of the corrosion resistance of a crystalline wasteform (monazite); (2) a study of the protective ability of the surface layer (gel layer) which forms on the nuclear waste glass Frit 21 + 20 wt % SRW in distilled water; and (3) making comparisons of the overall corrosion resistance of three different nuclear wasteforms (i.e., monazite, SYNROC, and borosilicate glass). A complete solution analysis of the borosilicate glass leachate and a straightforward analysis of the conductivity results agree to within +-20%. In the absence of a complete, time consuming solution analysis, conductivity measurements can be used to estimate reliably the total ionic concentration in the leachate to within a factor of 2

New method for solving inductive electric fields in the non-uniformly conducting ionosphere

Directory of Open Access Journals (Sweden)

H. Vanhamäki

2006-10-01

Full Text Available We present a new calculation method for solving inductive electric fields in the ionosphere. The time series of the potential part of the ionospheric electric field, together with the Hall and Pedersen conductances serves as the input to this method. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition, no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called the Cartesian Elementary Current Systems (CECS. This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfvén wave reflection from a uniformly conducting ionosphere.

New method for solving inductive electric fields in the non-uniformly conducting ionosphere

Science.gov (United States)

Vanhamäki, H.; Amm, O.; Viljanen, A.

2006-10-01

We present a new calculation method for solving inductive electric fields in the ionosphere. The time series of the potential part of the ionospheric electric field, together with the Hall and Pedersen conductances serves as the input to this method. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition, no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called the Cartesian Elementary Current Systems (CECS). This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfvén wave reflection from a uniformly conducting ionosphere.

Electrical conductivity of H2O-NaCl fluids to 10 kbar

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Sinmyo, R.; Keppler, H.

2016-12-01

Magnetotelluric studies often reveal zones of elevated electrical conductivity in the mantle wedge above subducting slabs, in the deep crust below fold belts, or below active volcanoes. Since both aqueous fluids and hydrous silivate melts may be highly conductive, they may both account for these observations. Distinguishing between these two posssibilities, however, is difficult. One reason for this problem is that while there are very good conductivity data for silicate melts, such data do not exist for aqueous fluids under the relevant conditions of pressure, temperature and solute concentration. Most crustal and mantle fluids likely contain some NaCl, which greatly enhances conductivity due to its partial dissociation into Na+ and Cl-. We therefore studied the electrical conductivity of 0.01, 0.1 and 1 m NaCl solutions in water to 10 kbar and 600 °C. The measurements were carried out in externally-heated diamond cells containing two gaskets separated by an insulating ring of diamond, following a method described by Ni et al. (2014). The two gaskets were used as electrodes and full impedance spectra were measured from 30 Hz to 10 MHz using a Solartron 1260 impedance analyzer. Electrical conductivity was generally found to increase with pressure temperature, and fluid density. The conductivity increase observed upon variation of NaCl concentration from 0.1m to 1m was smaller than from 0.01m to 0.1m, which reflects the reduced degree of dissociation at high NaCl concentration. In general, the data show that already a very small fraction of NaCl-bearing aqueous fluid is sufficient to enhance bulk conductivities to values that would be expected for a high degree of partial melting. Accordingly, aqueous fluids may be distinguished from hydrous melts by comparing magnetotelluric and seismic data. H2O-NaCl fluids may enhance electrical conductivities with little disturbance of vp or vp/vs ratios.

Carbon nanotube-coated silicone as a flexible and electrically conductive biomedical material

International Nuclear Information System (INIS)

Matsuoka, Makoto; Akasaka, Tsukasa; Totsuka, Yasunori; Watari, Fumio

2012-01-01

Artificial cell scaffolds that support cell adhesion, growth, and organization need to be fabricated for various purposes. Recently, there have been increasing reports of cell patterning using electrical fields. We fabricated scaffolds consisting of silicone sheets coated with single-walled (SW) or multi-walled (MW) carbon nanotubes (CNTs) and evaluated their electrical properties and biocompatibility. We also performed cell alignment with dielectrophoresis using CNT-coated sheets as electrodes. Silicone coated with 10 μg/cm 2 SWCNTs exhibited the least sheet resistance (0.8 kΩ/sq); its conductivity was maintained even after 100 stretching cycles. CNT coating also improved cell adhesion and proliferation. When an electric field was applied to the cell suspension introduced on the CNT-coated scaffold, the cells became aligned in a pearl-chain pattern. These results indicate that CNT coating not only provides electro-conductivity but also promotes cell adhesion to the silicone scaffold; cells seeded on the scaffold can be organized using electricity. These findings demonstrate that CNT-coated silicone can be useful as a biocompatible scaffold. - Highlights: ► We fabricated a CNT-coated silicone which has conductivity and biocompatibility. ► The conductivity was maintained after 100 cycles of stretching. ► CNT coatings enabled C2C12 cells adhere to the silicone surface. ► Cells were aligned with dielectrophoresis between CNT-coated silicone surfaces.

Graphite nanoplatelets and carbon nanotubes based polyethylene composites: Electrical conductivity and morphology

International Nuclear Information System (INIS)

Haznedar, Galip; Cravanzola, Sara; Zanetti, Marco; Scarano, Domenica; Zecchina, Adriano; Cesano, Federico

2013-01-01

Graphite nanoplatelets (GNPs) and/or multiwalled-carbon nanotubes (MWCNTs)/low density polyethylene (LDPE) composites have been obtained either via melt-mixing or solvent assisted methods. Electrical properties of samples obtained through the above mentioned methods are compared and the conductance values as function of filler fraction are discussed. The corresponding percolation thresholds are evaluated. Conductivity maps images are acquired under low-potentials scanning electron microscopy (0.3 KV) and the relationship between the obtained conductivity images and electric properties is highlighted. The synergistic role of CNTs (1D) and GNPs (2D) in improving the conductive properties of the polymer composites has been shown. - Highlights: • Graphite nanoplatelets (GNPs) and GNPs/MWCNT LDPE composites. • Low potential SEM conductivity maps. • Conducting paths between 1D and 2D C-structures (synergistic effect) are obtained. • Composites based on hybrid 1D/2D combinations show lower percolation thresholds

Effect of the type of metal on the electrical conductivity and thermal properties of metal complexes: The relation between ionic radius of metal complexes and electrical conductivity

Science.gov (United States)

Morgan, Sh. M.; El-Ghamaz, N. A.; Diab, M. A.

2018-05-01

Co(II) complexes (1-4) and Ni(II) complexes (5-8) were prepared and characterized by elemental analysis, IR spectra and thermal analysis data. Thermal decomposition of all complexes was discussed using thermogravimetric analysis. The dielectric properties and alternating current conductivity were investigated in the frequency range 0.1-100 kHz and temperature range 300-660 K. The thermal activation energies of electrical conductivity (ΔE1 and ΔE2) values for complexes were calculated and discussed. The values of ΔE1 and ΔE2 for complexes (1-8) were found to decrease with increasing the frequency. Ac electrical conductivity (σac) values increases with increasing temperatures and the values of σac for Co(II) complexes are greater than Ni(II) complexes. Co(II) complexes showed a higher conductivity than other Ni(II) complexes due to the higher crystallinity as confirmed by X-ray diffraction analysis.

Effective electrical conductivity of carbon nanotube-polymer composites: a simplified model and its validation

International Nuclear Information System (INIS)

Jang, Sung-Hwan; Yin, Huiming

2015-01-01

A simplified model is presented to predict the effective electrical conductivity of carbon nanotube(CNT)-polymer composite with different material proportions, which is validated by the experiments of multi-walled CNT/polydimethylsiloxane (PDMS) composites. CNTs are well dispersed in a PDMS matrix, and the mixture is then cured and cast into thin films for electrical characterization. The CNTs are assumed to be statistically uniformly distributed in the PDMS matrix with the three-dimensional (3D) waviness. As the proportion of CNTs increases to a certain level, namely the percolation threshold, the discrete CNTs start to connect with each other, forming a 3D network which exhibits a significant increase of effective electrical conductivity. The eight-chain model has been used to predict the effective electrical conductivity of the composite, in which the contact resistance between CNTs has been considered through the Simmons’ equation. The eight-chain network features can be significantly changed with the modification to mixing process, CNT length and diameter, and CNT clustering and curling. A Gaussian statistics-based formulation is used to calculate the effective length of a single CNT well dispersed in the matrix. The modeling results of effective electrical conductivity agree with the experiments very well, which are highly dependent on a contact resistance between CNTs and the waviness of the CNTs. The effect of inner-nanotube distance and diameter of CNTs on the effective electrical conductivity of the CNT/PDMS composite is also discussed. (paper)

Synthesis, structure and total conductivity of A-site doped LaTiO{sub 3−δ} perovskites

Energy Technology Data Exchange (ETDEWEB)

Bradha, M. [Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore 641 004, TN (India); Hussain, S.; Chakravarty, Sujay [UGC-DAE CSR, Kalpakkam Node, Kokilamedu 603 104, TN (India); Amarendra, G. [UGC-DAE CSR, Kalpakkam Node, Kokilamedu 603 104, TN (India); Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, TN (India); Ashok, Anuradha, E-mail: anu.machina@gmail.com [Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore 641 004, TN (India)

2015-03-25

Highlights: • A-site divalent alkaline earth metal doped LaTiO{sub 3−δ} perovskites were synthesised by sol–gel method. • Structural studies revealed no change in crystal symmetry but change in cell dimensions after doping. • After doping divalent cations in A-site, an enhancement in total conductivity was observed in LaTiO{sub 3−δ}. • Temperature dependent electrical property was observed in all synthesised perovskites. - Abstract: Oxygen deficient perovskites LaTiO{sub 3−δ} and La{sub 0.8}A{sub 0.2}TiO{sub 3−δ} (A = Ba, Sr, Ca) were synthesized by sol–gel method. The effect of divalent dopants on microstructure is investigated in detail using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The oxidation states of La{sup 3+} and Ti{sup 3+} ions have been deduced using X-ray Photoelectron Spectroscopy (XPS). Impedance spectroscopy was used to analyze the total conductivity, an increase in conductivity was observed after doping in the A-site with divalent cations Ba, Ca and Sr. Among the investigated perovskites La{sub 0.8}Ca{sub 0.2}TiO{sub 3−δ} exhibited the maximum conductivity of 1.22 × 10{sup −2} S/cm in air atmosphere at 650 °C.

Electric conductivity of salt melts containing KCL, KF and K2TaF7

International Nuclear Information System (INIS)

Agulyanskij, A.I.; Stangrit, P.T.; Konstantinov, V.I.

1978-01-01

Given are electric conductivity measurement results depending on the temperature and composition of the molten KF-K 2 TaF 7 , KCl-K 2 TaF 7 systems and also melts close in their composition to industrial electrolytes, KCl-KF (in mass ratio of 2:1) with addition of K 2 TaF 7 up to 25 mass%. Presented are electric conductivity molecular isotherms of the KF-K 2 TaF 7 , KCl-K 2 TaF 7 systems at 800 deg C and specific electric conductivity dependence of KCl-KF-K 2 TaF 7 melts on K 2 TaF 7 composition at 800 deg C and 900 deg C. Proceeding from the shape of molecular and specific electric conductivity isotherms a conclusion is made about existence of the following tantalum-containing ions: TaF 7 2- , TaF 6 - and TaF 6 Cl 2- in the investigated melts

The study of human bodies' impedance networks in testing leakage currents of electrical equipments

Science.gov (United States)

Zhang, Zhaohui; Wang, Xiaofei

2006-11-01

In the testing of electrical equipments' leakage currents, impedance networks of human bodies are used to simulate the current's effect on human bodies, and they are key to the preciseness of the testing result. This paper analyses and calculates three human bodies' impedance networks of measuring electric burn current, perception or reaction current, let-go current in IEC60990, by using Matlab, compares the research result of current effect thresholds' change with sine wave's frequency published in IEC479-2, and amends parameters of measuring networks. It also analyses the change of perception or reaction current with waveform by Multisim.

Alterations in body fluid content can be detected by bioelectrical impedance analysis.

Science.gov (United States)

Scheltinga, M R; Jacobs, D O; Kimbrough, T D; Wilmore, D W

1991-05-01

The electrical resistance across the whole body and its segments to the conduction of a weak alternating current was determined in human subjects under three different conditions: (1) during bed rest, (2) during infusion of 1 liter of saline, and (3) during donation of 1 unit of blood. During bed rest, extracellular and total body water were measured by dilution of bromide and heavy water, respectively. Electrical resistance obtained from electrodes placed on proximal portions of extremities ("proximal resistance") accounted for less than 50% of that determined by electrodes positioned on routinely used portions of a hand and foot ("whole body resistance"). Following saline infusion, resistance determined from the whole body and all its segments fell (P less than 0.001); the magnitude of the drop in both proximal and whole body resistance was inversely related to the volume of total body water (TBW) (r = -0.82, P less than 0.002, and r = -0.73, P less than 0.01, respectively). In contrast, blood donation was associated with significantly increased resistance at both measurement sites. TBW predicted from anthropometrics was inversely related to both proximal (r = -0.90, P less than 0.001) and whole body resistance (r = -0.75, P less than 0.001). Bioelectrical impedance analysis is a simple technique which may be useful in monitoring minimal alterations in TBW. Furthermore, altered fluid status may be predicted more accurately by changes in proximal resistance compared to changes in traditionally used whole body resistance.

What we can learn from measurements of air electric conductivity in 222Rn-rich atmosphere

Science.gov (United States)

Seran, E.; Godefroy, M.; Pili, E.; Michielsen, N.; Bondiguel, S.

2017-02-01

Electric conductivity of air is an important characteristic of the electric properties of an atmosphere. Testing instruments to measure electric conductivity ranging from 10-13 to 10-9 S m-1 in natural conditions found in the Earth atmosphere is not an easy task. One possibility is to use stratospheric balloon flights; another (and a simpler one) is to look for terrestrial environments with significant radioactive decay. In this paper we present measurements carried out with different types of conductivity sensors in two 222Rn-rich environments, i.e., in the Roselend underground tunnel (French Alps) and in the Institute of Radioprotection and Nuclear Safety BACCARA (BAnC de CAllibrage du RAdon) chamber. The concept of the conductivity sensor is based on the classical time relaxation method. New elements in our design include isolation of the sensor sensitive part (electrode) from the external electric field and sensor miniaturization. This greatly extends the application domain of the sensor and permits to measure air electric conductivity when the external electric field is high and varies from few tens of V m-1 to up to few tens of kV m-1. This is suitable to propose the instrument for a planetary mission. Two-fold objectives were attained as the outcome of these tests and their analysis. First was directly related to the performances of the conductivity sensors and the efficiency of the conductivity sensor design to shield the external electric field. Second objective aimed at understanding the decay mechanisms of 222Rn and its progeny in atmosphere and the impact of the enclosed space on the efficiency of gas ionization.

Anisotropic modelling of the electrical conductivity of fractured bedrock

International Nuclear Information System (INIS)

Flykt, M.J.; Sihvola, A.H.; Eloranta, E.H.

1995-01-01

The electromagnetic characterization of fractured bedrock is of importance when studying the final disposal of nuclear waste. The different types of discontinuities at all scales in rocks can be viewed as an inhomogeneity. In some cases there are reasons to assume the influence of the discontinuities on electrical conductivity is anisotropic in character. The effort has been made to use electromagnetic mixing rules in the definition of an equivalent homogeneous anisotropic conductivity tensor for such fractured rock mass. (author) (16 refs., 6 figs.)

Fluorine follows water: Effect on electrical conductivity of silicate minerals by experimental constraints from phlogopite

Science.gov (United States)

Li, Yan; Jiang, Haotian; Yang, Xiaozhi

2017-11-01

Fluorine and hydroxyl groups are minor constituents of silicate minerals, and share a lot of similarities concerning their physical and chemical properties. Hydroxyl groups significantly enhance the electrical conductivity of many silicate minerals, and it is expected that fluorine would have a comparable effect. This, however, has never been documented quantitatively. Here we present experimental approaches on this issue, by investigating the electrical conductivity of phlogopite with a wide range of fluorine content (but with broadly similar contents for other major elements). Electrical conductivities of gem-quality single crystal phlogopites, with samples prepared along the same orientation (normal to the (0 0 1) plane), were determined at 1 GPa and 200-650 °C using an end-loaded piston cylinder apparatus and a Solartron-1260 Impedance/Gain Phase Analyzer over the frequency range of 106 to 0.1 Hz. The complex spectra usually show an arc in the high frequency range and a short tail in the low frequency range, which are caused by lattice conduction and electrode effects, respectively. The electrical conductivity increases with increasing fluorine content, and the main charge carriers are fluorine. The activation enthalpies are ∼180 to 200 kJ/mol, nearly independent of fluorine content. The conductivity is linearly proportional to the content of fluorine, with an exponent factor of ∼1. The results demonstrate that conduction by fluorine leads to very high electrical conductivity at high temperatures. The influence of fluorine on electrical conductivity may be compared to that of hydrogen in nominally anhydrous minerals. This, along with the close association of fluorine and hydroxyl groups in silicate minerals and their similar crystal-chemical behaviors, suggests a more general role of fluorine in enhancing the electrical conductivity of many silicate minerals. Fluorine-rich assemblages, e.g., phlogopite and amphibole, could be locally enriched in the upper

Observations on total-body calcium in humans with bone disease

International Nuclear Information System (INIS)

Spinks, T.J.; Bewley, D.K.; Ranicar, A.S.O.; Joplin, G.F.; Evans, I.M.A.; Vlotides, J.; Paolillo, M.

1979-01-01

Total-body calcium was measured in-vivo by neutron activation in a number of patients suffering from metabolic abnormalities which affect the skeleton. In general, less than 2% of total calcium resides in tissue other than bone allowing calcium mass to be directly related to skeletal mass. The conditions studied were (i) Paget's disease, treated with synthetic human calcitonin, (ii) osteoporosis, treated variously with calcium and phosphate supplements and 1,25 hydroxycholecalciferol, and (iii) Cushing's disease treated by pituitary implant of 198 Au or 90 Y seeds. The neutron beam used in these studies was produced by bombarding a beryllium target with deuterons accelerated in a cyclotron. The mean neutron energy was 7.5 MeV and patients received a total dose of 1 rem in about 30 s, a bilateral irradiation being employed. Measurements were made at approximately yearly intervals, the maximum period of study being about four and a half years. The precision of the method was estimated to be +-3% (SE) and a correction was applied for changes in body weight. In most patients, total calcium remained stable. However, in the Paget's patients, there was an indication of a slow upward trend while the osteoporotics (both treated and untreated) showed on average no change. Most of the patients with Cushing's disease showed no recovery of skeletal mass. Absolute calibration indicated that mean total body calcium in the Paget's patients was close to a predicted normal while that for the osteoporotic and Cushing's patients was 20-25% below this. (author)

Electrical conductivity imaging in the western Pacific subduction zone

Science.gov (United States)

Utada, Hisashi; Baba, Kiyoshi; Shimizu, Hisayoshi

2010-05-01

Oceanic plate subduction is an important process for the dynamics and evolution of the Earth's interior, as it is regarded as a typical downward flow of the mantle convection that transports materials from the near surface to the deep mantle. Recent seismological study showed evidence suggesting the transportation of a certain amount of water by subduction of old oceanic plate such as the Pacific plate down to 150-200 km depth into the back arc mantle. However it is not well clarified how deep into the mantle the water can be transported. The electromagnetic induction method to image electrical conductivity distribution is a possible tool to answer this question as it is known to be sensitive to the presence of water. Here we show recent result of observational study from the western Pacific subduction zone to examine the electrical conductivity distribution in the upper mantle and in the mantle transition zone (MTZ), which will provide implications how water distributes in the mantle. We take two kinds of approach for imaging the mantle conductivity, (a) semi-global and (b) regional induction approaches. Result may be summarized as follows: (a) Long (5-30 years) time series records from 8 submarine cables and 13 geomagnetic observatories in the north Pacific region were analyzed and long period magnetotelluric (MT) and geomagnetic deep sounding (GDS) responses were estimated in the period range from 1.7 to 35 days. These frequency dependent response functions were inverted to 3-dimensional conductivity distribution in the depth range between 350 and 850 km. Three major features are suggested in the MTZ depth such as, (1) a high conductivity anomaly beneath the Philippine Sea, (2) a high conductivity anomaly beneath the Hawaiian Islands, and (3) a low conductivity anomaly beneath and in the vicinity of northern Japan. (b) A three-year long deployment of ocean bottom electro-magnetometers (OBEM's) was conducted in the Philippine Sea and west Pacific Ocean from 2005

INVESTIGATION OF HEAT CONDUCTION AND SPECIFIC ELECTRIC IMPEDANCE OF POROUS MATERIALS

Directory of Open Access Journals (Sweden)

E. S. Golubtsova

2004-01-01

Full Text Available In this article there was investigated the influence of porosity and temperature change on heat condition and electrical resistance of porous iron (PZh4M nickel and steel 14X17H2. There are received the adequate equations of regression, establishing connection between heat conduction and electrical resistance of the investigated materials with their porosity and temperature.

Effect of aflatoxin ingestion on total body water (T OH3 - space), total body solids A KD on some physiological and reproductive characteristics of male albino rats

International Nuclear Information System (INIS)

Nowar, M.S.; Eldarawany, A.A.; Habeeb, A.A.

1992-01-01

This investigation aimed to study the effects of aflatoxins B 1 +G 1 mixture mainly on total body water (TBW) and on total body solids (TBS) of male albino rats. Some blood components and some reproductive characteristic were also taken into consideration. Two groups, each of 8 male rats were fed the same ration. Rats of one group had been individually ingested daily with a dose of 22 μg B 1 plus 22 μg G 1 for 15 successive weeks. The obtained results showed that aflatoxin administration caused: 1- A decrease in final body weight (FBW), TBW (P<0.01) and TBS (P<0.05). 2- A decrease in serum total proteins (P<0.01), albumin (P<0.05), globulin (P<0.05), glucose (P<0.05) and increase in serum cholesterol, GOT and GPT (P<0.05) activities. 3- A decrease in each of the number of effective matings of males and delivery percentages of females mated with treated males.1 tab

Feasibility of Imaging Tissue Electrical Conductivity by Switching Field Gradients with MRI.

Science.gov (United States)

Gibbs, Eric; Liu, Chunlei

2015-12-01

Tissue conductivity is a biophysical marker of tissue structure and physiology. Present methods of measuring tissue conductivity are limited. Electrical impedance tomography, and magnetic resonance electrical impedance tomography rely on passing external current through the object being imaged, which prevents its use in most human imaging. Recently, the RF field used for MR excitation has been used to non-invasively measure tissue conductivity. This technique is promising, but conductivity at higher frequencies is less sensitive to tissue structure. Measuring tissue conductivity non-invasively at low frequencies remains elusive. It has been proposed that eddy currents generated during the rise and decay of gradient pulses could act as a current source to map low-frequency conductivity. This work centers on a gradient echo pulse sequence that uses large gradients prior to excitation to create eddy currents. The electric and magnetic fields during a gradient pulse are simulated by a finite-difference time-domain simulation. The sequence is also tested with a phantom and an animal MRI scanner equipped with gradients of high gradient strengths and slew rate. The simulation demonstrates that eddy currents in materials with conductivity similar to biological tissue decay with a half-life on the order of nanoseconds and any eddy currents generated prior to excitation decay completely before influencing the RF signal. Gradient-induced eddy currents can influence phase accumulation after excitation but the effect is too small to image. The animal scanner images show no measurable phase accumulation. Measuring low-frequency conductivity by gradient-induced eddy currents is presently unfeasible.

Characterization of electrical conductivity of carbon fiber reinforced plastic using surface potential distribution

Science.gov (United States)

Kikunaga, Kazuya; Terasaki, Nao

2018-04-01

A new method of evaluating electrical conductivity in a structural material such as carbon fiber reinforced plastic (CFRP) using surface potential is proposed. After the CFRP was charged by corona discharge, the surface potential distribution was measured by scanning a vibrating linear array sensor along the object surface with a high spatial resolution over a short duration. A correlation between the weave pattern of the CFRP and the surface potential distribution was observed. This result indicates that it is possible to evaluate the electrical conductivity of a material comprising conducting and insulating regions.

Correlation of total body potassium and leukemic cell mass in patients with chronic lymphocytic leukemia

International Nuclear Information System (INIS)

Chandra, P.; Sawitsky, A.; Chanana, A.D.; Chikkappa, G.; Cohn, S.H.; Rai, K.R.; Cronkity, E.P.

1979-01-01

Total body leukemic mass in patients with chronic lymphocytic leukemia (CLL) was measured by quantitation of total body potassium (TBK) with a whole-body counter. In addition, the predicted normal total body potassium (Kp) for each patient was calculated from an empirically derived relationship involving height, weight age, and sex. Both the absolute TBK and the relative excess of total body potassium (TBK/Kp) were related to the stage of disease. Patients in the early stages of CLL were found to have lower TBK and TBK/Kp than patients in the late stages of disease. Both of these parameters increased with the successively advanced stages of the disease. The clinically monitored reduction of leukemic cell mass following therapy was accompanied by reductions in TBK and TBK/Kp. Data presented support the notion that TBK/Kp is a useful indicator of the total body leukemic mass. Futhermore, the results of these studies quantitatively validate the proposed clinical staging system for CLL. Quantitation of TBK by a whole-body counter is an accurate and noninvasive procedure and does not require administration of isotopes

Effect of process parameters on microstructure and electrical conductivity during FSW of Al-6101 and Pure Copper

Science.gov (United States)

Sharma, Nidhi; Khan, Zahid A.; Siddiquee, Arshad Noor; Shihab, Suha K.; Atif Wahid, Mohd

2018-04-01

Copper (Cu) is predominantly used material as a conducting element in electrical and electronic components due to its high conductivity. Aluminum (Al) being lighter in weight and more conductive on weight basis than that of Cu is able to replace or partially replace Cu to make lighter and cost effective electrical components. Conventional methods of joining Al to Cu, such as, fusion welding process have many shortcomings. Friction Stir Welding (FSW) is a solid state welding process which overcomes the shortcoming of the fusion welding. FSW parameters affect the mechanical and electrical properties of the joint. This study aims to evaluate the effect of different process parameters such as shoulder diameter, pin offset, welding and rotational speed on the microstructure and electrical conductivity of the dissimilar Al-Cu joint. FSW is performed using cylindrical pin profile, and four process parameters. Each parameter at different levels is varied according to Taguchi’s L18 standard orthogonal array. It is found that the electrical conductivity of the FSWed joints are equal to that of aluminum at all the welded sections. FSW is found to be an effective technique to join Al to Cu without compromising with the electrical properties. However, the electrical conductivity gets influenced by the process parameters in the stir zone. The optimal combination of the FSW parameters for maximum electrical conductivity is determined. The analysis of variance (ANOVA) technique applied on stir zone suggests that the rotational speed and tool pin offset are the significant parameters to influence the electrical conductivity.

Influence of Electrical Conductivity, Days in Milk and Parity on Milk Production and Chemical Composition

Directory of Open Access Journals (Sweden)

Radu Ionel Neamț

2016-10-01

Full Text Available The aim of study was to assess milk production and chemical composition during the first 100 days of lactation, under the influence of electrical conductivity, parity and days in milk. Study was conducted at Research and Development Station for Bovine Arad, on 66 Romanian Spotted cows (20 primiparous, 46 multiparous. Significantly higher values (p≤0.017 of electrical conductivity were recorded for primiparous (10.15±0.09 mS/cm compared with multiparous (8.79±0.15 mS/cm. During the first 30 DIM electrical conductivity was higher (9.7±0.12 mS/cm than for 31 to 60 DIM (9.04±0.12 mS/cm; p≤0.001 and for 61 to 100 DIM (8.17±0.11 mS/cm, p≤0.001. Multifactorial regression model applied highlights significant influence of month of calving (p≤0.001 and DIM (p≤0.034 on the electrical conductivity, while parity had no influence (p>0.36. Medium and negative correlations were calculated between electrical conductivity and some chemical components (fat R=-0.15, protein R=-0.13, while to milk production correlation was positive (R=0.12. No significant correlations were obtained according to lactose content (R=-0.013. Dynamics of milk production and chemical composition have been significantly influenced by month of calving (p≤0.001, DIM (p≤0.001 and parity (p≤0.002. This study found no significant influence of milk electrical conductivity on milk production or chemical composition (p>0.59.

From Talking Heads to Communicating Bodies: Cybersemiotics and Total Communication

Directory of Open Access Journals (Sweden)

Ole Nedergaard Thomsen

2010-03-01

Full Text Available Current linguistics is biased towards considering as object of scientific study only verbal language, i.e., ordinary language whose basic entities are words, sentences, and texts. By having this focus, the crucial non-verbal semiotic contributions from acts of bodily communication are left out of consideration. On the face of it, this is a strange situation, because, phenomenologically, when observing a communicating dyad, what appears to the senses is a multimodal semiotic display–the interactants produce acts of total communication, the linguistic part of which has in fact to be disentangled from the integral semiotic behavior. That a human being should in the first place be conceptualized as a ‘talking head’, rather than a ‘communicating body’, stems from at least four historically interrelated fountains: ancient Greek philosophy with its emphasis on logos as meaning both rational mind and verbal language/speech as well as with its rejection of rhetoric (including body language; Cartesian dualistic rationalism where the body was the animal, mechanistic part of a human being, unworthy for the Geisteswissenschaften; Saussure’s formal structuralism with its defocusing of the individual’s performance, parole, and its high focus on societal langue; and Chomskyan linguistics with its neglect of actual, also bodily, performance, and its total focus on an ideal mental grammatical computational competence. With the recent philosophy (‘in the flesh’ of the ‘embodied mind’, time has now come for integrating the (linguistic head with the (other part of the communicating body and seeing communication as total communication of the whole body. This means that the communicating mind is no longer restricted to its ‘rational’ aspects but has to be conceived full-scale as integrating also all kinds of ‘irrational’ factors, like emotions and motivations. Another, no less important, implication of the above is that an individual�

State of hydration and electrical conductance of ichthyotic skin

OpenAIRE

A B Gupta; Manisha Bhattacharya; B Haldar

1990-01-01

Dry skin of twelve subjects suffering from ichthyosis vulgaris and the efficacy of a moisturiser-Cotaryl were quantitatively assessed by measuring the skin surface hydration and high frequency (3.5 MHz) electrical conductance of skin. The state of hydration and conductance of ichthyotic skin were 86.9 + 24.6 and 11.0 + 5.7 micro-mho respectively, being much less-compared to 132. 0 + 5.3 and 72.5 + 54.0 micro-mho ofnormal subjects. The moisturiser increased the state of hydration and also the ...

Heterogeneous in situ polymerization of polyaniline (PANI) nanofibers on cotton textiles: Improved electrical conductivity, electrical switching, and tuning properties.

Science.gov (United States)

Tissera, Nadeeka D; Wijesena, Ruchira N; Rathnayake, Samantha; de Silva, Rohini M; de Silva, K M Nalin

2018-04-15

Electrically conductive cotton fabric was fabricated by in situ one pot oxidative polymerization of aniline. Using a simple heterogeneous polymerization method, polyaniline (PANI) nano fibers with an average fiber diameter of 40-75 nm were grafted in situ onto cotton fabric. The electrical conductivity of the PANI nanofiber grafted fabric was improved 10 fold compared to fabric grafted with PANI nanoclusters having an average cluster size of 145-315 nm. The surface morphology of the cotton fibers was characterized using SEM and AFM. Electrical conductivity of PANI nanofibers on the cotton textile was further improved from 76 kΏ/cm to 1 kΏ/cm by increasing the HCl concentration from 1 M to 3 M in the polymerization medium. PANI grafted cotton fabrics were analyzed using FTIR, and the data showed the presence of polyaniline functional groups on the treated fabric. Further evidence was present for the chemical interaction of PANI with cellulose. Dopant level and morphology dependent electron transition behavior of PANI nanostructures grafted on cotton fabric was further characterized using UV-vis spectroscopy. The electrical conductivity of the PANI nano fiber grafted cotton fabric can be tuned by immersing the fabric in pH 2 and pH 6 solutions for multiple cycles. Copyright © 2018. Published by Elsevier Ltd.

Influence of calcium and lithium on the densification and electrical conductivity of gadolinia-doped ceria

International Nuclear Information System (INIS)

Porfirio, Tatiane Cristina

2011-01-01

In this work, the use of calcium and lithium as sintering aid to gadolinia-doped ceria was systematically investigated. The main purpose was to verify the influence of these additives on the densification and electrical conductivity of sintered ceramics. Powder compositions containing up to 1.5 mol% (metal basis) of calcium or lithium were prepared by both solid state reaction and oxalate coprecipitation methods. The main characterization techniques were thermal analyses, X-ray diffraction, scanning electron microscopy and electrical conductivity by impedance spectroscopy. Both additives promoted densification of gadolinia-doped ceria. The densification increases with increasing the additive content. Different effects on microstructure and electrical conductivity result from the method of preparation, e.g., solid state reaction or coprecipitation. Calcium addition greatly enhances the grain growth compared to lithium addition. The electrical conductivity of specimens containing a second additive is lower than that of pure gadolinia-doped ceria. Both additives influence the intergranular conductivity and favor the exudation of gadolinium out of the solid solution. (author)

Electrical conductivity of solutions of copper(II) nitrate crystalohydrate in dimethyl sulfoxide

Science.gov (United States)

Mamyrbekova, Aigul K.; Mamitova, A. D.; Mamyrbekova, Aizhan K.

2016-06-01

Conductometry is used to investigate the electric conductivity of Cu(NO3)2 ṡ 3H2O solutions in dimethyl sulfoxide in the 0.01-2.82 M range of concentrations and at temperatures of 288-318 K. The limiting molar conductivity of the electrolyte and the mobility of Cu2+ and NO 3 - ions, the effective coefficients of diffusion of copper(II) ions and nitrate ions, and the degree and constant of electrolytic dissociation are calculated for different temperatures from the experimental results. It is established that solutions containing 0.1-0.6 M copper nitrate trihydrate in DMSO having low viscosity and high electrical conductivity can be used in electrochemical deposition.

Electrically Conductive TPU Nanofibrous Composite with High Stretchability for Flexible Strain Sensor

Science.gov (United States)

Tong, Lu; Wang, Xiao-Xiong; He, Xiao-Xiao; Nie, Guang-Di; Zhang, Jun; Zhang, Bin; Guo, Wen-Zhe; Long, Yun-Ze

2018-03-01

Highly stretchable and electrically conductive thermoplastic polyurethane (TPU) nanofibrous composite based on electrospinning for flexible strain sensor and stretchable conductor has been fabricated via in situ polymerization of polyaniline (PANI) on TPU nanofibrous membrane. The PANI/TPU membrane-based sensor could detect a strain from 0 to 160% with fast response and excellent stability. Meanwhile, the TPU composite has good stability and durability. Besides, the composite could be adapted to various non-flat working environments and could maintain opportune conductivity at different operating temperatures. This work provides an easy operating and low-cost method to fabricate highly stretchable and electrically conductive nanofibrous membrane, which could be applied to detect quick and tiny human actions.

Investigation on magnetoacoustic signal generation with magnetic induction and its application to electrical conductivity reconstruction

International Nuclear Information System (INIS)

Ma Qingyu; He Bin

2007-01-01

A theoretical study on the magnetoacoustic signal generation with magnetic induction and its applications to electrical conductivity reconstruction is conducted. An object with a concentric cylindrical geometry is located in a static magnetic field and a pulsed magnetic field. Driven by Lorentz force generated by the static magnetic field, the magnetically induced eddy current produces acoustic vibration and the propagated sound wave is received by a transducer around the object to reconstruct the corresponding electrical conductivity distribution of the object. A theory on the magnetoacoustic waveform generation for a circular symmetric model is provided as a forward problem. The explicit formulae and quantitative algorithm for the electrical conductivity reconstruction are then presented as an inverse problem. Computer simulations were conducted to test the proposed theory and assess the performance of the inverse algorithms for a multi-layer cylindrical model. The present simulation results confirm the validity of the proposed theory and suggest the feasibility of reconstructing electrical conductivity distribution based on the proposed theory on the magnetoacoustic signal generation with magnetic induction

Impurity effects on electrical conductivity of doped bilayer graphene in the presence of a bias voltage

International Nuclear Information System (INIS)

Lotfi, E; Rezania, H; Arghavaninia, B; Yarmohammadi, M

2016-01-01

We address the electrical conductivity of bilayer graphene as a function of temperature, impurity concentration, and scattering strength in the presence of a finite bias voltage at finite doping, beginning with a description of the tight-binding model using the linear response theory and Green’s function approach. Our results show a linear behavior at high doping for the case of high bias voltage. The effects of electron doping on the electrical conductivity have been studied via changing the electronic chemical potential. We also discuss and analyze how the bias voltage affects the temperature behavior of the electrical conductivity. Finally, we study the behavior of the electrical conductivity as a function of the impurity concentration and scattering strength for different bias voltages and chemical potentials respectively. The electrical conductivity is found to be monotonically decreasing with impurity scattering strength due to the increased scattering among electrons at higher impurity scattering strength. (paper)

Fractionated homogenous total-body irradiation prior to bone marrow transplantation

Energy Technology Data Exchange (ETDEWEB)

Duehmke, E; Brix, F; Hebbinghaus, D; Jensen, M; Wendhausen, H; Schmitz, N

1985-03-01

At the University of Kiel, myeloid and acute lymphatic leukemia is treated since 1983 by total-body irradiation applied prior to bone marrow transplantation. Dose deviations in the midplane caused by the irregular surface and tissue inhomogeneities of the patient are reduced down to +-3.5% compared to the central ray, with the help of CT-based individual compensators. This method prevents above all an excessive dose to the lungs. The radiobiologic advantages of fractionated irradiation have been employed for all patients treated hitherto (n = 9). At present, a total body dose of 12 Gy in six fractions is applied within three days. There were no undesired acute radiogenic reactions except a mild acute mucositis found in all patients. Chronic side effects, especially in the lungs, were not demonstrated, too. However, the average follow-up time of 149 days has been rather short. One patient died from relapse of leukemia after a total dose of 10 Gy, another patient died because the transplanted bone marrow was rejected, and a third died from catheter sepsis. Six out of nine patients are in complete remission with a maximum index of Karnofsky. The limited experiences gained hitherto show that the homogeneous accelerated-fractionated total-body irradiation offers essential advantages compared to non-compensated single dose irradiation with respect to the prevention of undesired radiogenic effects in sound tissues and that its therapeutic efficacy is at least the same.

Correlation between electrical conductivity and apparent diffusion coefficient in breast cancer: effect of necrosis on magnetic resonance imaging.

Science.gov (United States)

Kim, Soo-Yeon; Shin, Jaewook; Kim, Dong-Hyun; Kim, Eun-Kyung; Moon, Hee Jung; Yoon, Jung Hyun; You, Jai Kyung; Kim, Min Jung

2018-03-06

To investigate the correlation between conductivity and ADC in invasive ductal carcinoma according to the presence of necrosis on MRI. Eighty-one women with invasive ductal carcinoma ≥1 cm on T2-weighted fast spin echo sequence of preoperative MRI were included. Phase-based MR electric properties tomography was used to reconstruct conductivity. Mean ADC was measured. Necrosis was defined as an area with very high T2 signal intensity. The relationship between conductivity and ADC was examined using Spearman's correlation coefficient (r). Multiple linear regression analysis was performed to identify factors associated with conductivity or ADC. In the total group, conductivity showed negative correlation with ADC (r = -0.357, p = 0.001). This correlation was maintained in the subgroup without necrosis (n = 53, r = -0.455, p = 0.001), but not in the subgroup with necrosis (n = 28, r = -0.080, p = 0.687). The correlation between the two parameters was different according to necrosis (r = -0.455 vs -0.080, p = 0.047). HER2 enriched subtype was independently associated with conductivity (p = 0.029). Necrosis on MRI was independently associated with ADC (p = 0.027). Conductivity shows negative correlation with ADC that is abolished by the presence of necrosis on MRI. • Electric conductivity showed negative correlation with ADC • However, the correlation was abolished by the presence of necrosis on MRI • HER2-enriched subtype was independently associated with conductivity • Necrosis on MRI was independently associated with ADC.

Simultaneous reconstruction of outer boundary shape and conductivity distribution in electrical impedance tomography

KAUST Repository

Hyvö nen, Nuutti

2016-01-01

The simultaneous retrieval of the exterior boundary shape and the interior admittivity distribution of an examined body in electrical impedance tomography is considered. The reconstruction method is built for the complete electrode model

Total body photography for skin cancer screening.

Science.gov (United States)

Dengel, Lynn T; Petroni, Gina R; Judge, Joshua; Chen, David; Acton, Scott T; Schroen, Anneke T; Slingluff, Craig L

2015-11-01

Total body photography may aid in melanoma screening but is not widely applied due to time and cost. We hypothesized that a near-simultaneous automated skin photo-acquisition system would be acceptable to patients and could rapidly obtain total body images that enable visualization of pigmented skin lesions. From February to May 2009, a study of 20 volunteers was performed at the University of Virginia to test a prototype 16-camera imaging booth built by the research team and to guide development of special purpose software. For each participant, images were obtained before and after marking 10 lesions (five "easy" and five "difficult"), and images were evaluated to estimate visualization rates. Imaging logistical challenges were scored by the operator, and participant opinion was assessed by questionnaire. Average time for image capture was three minutes (range 2-5). All 55 "easy" lesions were visualized (sensitivity 100%, 90% CI 95-100%), and 54/55 "difficult" lesions were visualized (sensitivity 98%, 90% CI 92-100%). Operators and patients graded the imaging process favorably, with challenges identified regarding lighting and positioning. Rapid-acquisition automated skin photography is feasible with a low-cost system, with excellent lesion visualization and participant acceptance. These data provide a basis for employing this method in clinical melanoma screening. © 2014 The International Society of Dermatology.

Electrical conductivity of quasi-two-dimensional foams.

Science.gov (United States)

Yazhgur, Pavel; Honorez, Clément; Drenckhan, Wiebke; Langevin, Dominique; Salonen, Anniina

2015-04-01

Quasi-two-dimensional (quasi-2D) foams consist of monolayers of bubbles squeezed between two narrowly spaced plates. These simplified foams have served successfully in the past to shed light on numerous issues in foam physics. Here we consider the electrical conductivity of such model foams. We compare experiments to a model which we propose, and which successfully relates the structural and the conductive properties of the foam over the full range of the investigated liquid content. We show in particular that in the case of quasi-2D foams the liquid in the nodes needs to be taken into account even at low liquid content. We think that these results may provide different approaches for the characterization of foam properties and for the in situ characterization of the liquid content of foams in confining geometries, such as microfluidics.

Application of equivalent electrodes method to analysis of interaction between ELF-LF electric fields and human body

International Nuclear Information System (INIS)

Ceselkoska, Vesna C.; Velickovic, Dragutin M.

2002-01-01

This paper presents the use of equivalent electrodes method, numerical method, based on surface-charge equation to quantify the interaction of low frequencies electric fields with various models of human body. The evaluation of the electric field intensity on the body surface is performed for a realistic model of the human body. Several examples for different postures of the model are given. (Author)

Dielectric constant and electrical conductivity of contaminated fine-grained soils and barrier materials

International Nuclear Information System (INIS)

Kaya, A.; Fang, H.Y.; Inyang, H.I.

1997-01-01

Characterization of contaminated fine-grained soils and tracking of contaminant migration within barriers have been challenging because current methods and/or procedures are labor and time-intensive, and destructive. To demonstrate the effective use of both dielectric constant and electrical conductivity in the characterization of contaminated fine-grained soils, pore fluids were prepared at different ionic strengths, and were used as permeates for kaolinite, bentonite and a local soil. Then, both dielectric constant and electrical conductivity of the soils were measured by means of a capacitor over a wide range of frequencies and moisture content. It was observed that although each soil has its unique dielectric constant and electrical conductivity at a given moisture content, increases in ionic strength cause a decrease in the dielectric constant of the system at very high frequencies (MHZ), whereas the dielectric constant increases at low frequencies (kHz). Electrical conductivity of a soil-water system is independent of frequency. However, it is a function of ionic strength of the pore fluid. It is clearly demonstrated that dielectric constant and electrical conductivity of soils are functions of both moisture content and ionic strength, and can be used to characterize the spatial and temporal levels of contamination. This method/procedure can be used in estimating the level of contamination as well as the direction of contaminant movement in the subsurface without the use of extensive laboratory testing. Based on obtained results, it was concluded that the proposed method/procedure is promising because it is non-destructive and provides a quick means of assessing the spatial distribution of contaminants in fine-grained soils and barriers

Increase of Total Body Water with Decrease of Body Mass while Running 100 km Nonstop--Formation of Edema?

Science.gov (United States)

Knechtle, Beat; Wirth, Andrea; Knechtle, Patrizia; Rosemann, Thomas

2009-01-01

We investigated whether ultraendurance runners in a 100-km run suffer a decrease of body mass and whether this loss consists of fat mass, skeletal muscle mass, or total body water. Male ultrarunners were measured pre- and postrace to determine body mass, fat mass, and skeletal muscle mass by using the anthropometric method. In addition,…

Electrical conductivity and pH of groundwater: important exploratory ...

African Journals Online (AJOL)

Electrical conductivity and pH of groundwater: important exploratory tools in groundwater surveys. ... Journal of Technology and Education in Nigeria ... An analysis of the spatial variation of these parameters indicates that the EC and pH values of groundwater allow us to make deductions not only on the changes in the ...

Influence of electrical conductivity on microorganisms and rate of ...

African Journals Online (AJOL)

Salt treatments included NaCI amendments to adjust the soil solution electrical conductivities (EC) to 40, 120 and 200 dSm-1. Treated soils were incubated at 28OC. Oil degradation was estimated from the gravimetric determinations of remaining oil. The results showed that amending the ultisol with crude oil stimulated the ...

Evaluation of electrical and thermal conductivity of polymeric wastes ...

African Journals Online (AJOL)

This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with varying ...

Electrical conductivity of activated carbon-metal oxide nanocomposites under compression: a comparison study.

Science.gov (United States)

Barroso-Bogeat, A; Alexandre-Franco, M; Fernández-González, C; Macías-García, A; Gómez-Serrano, V

2014-12-07

From a granular commercial activated carbon (AC) and six metal oxide (Al2O3, Fe2O3, SnO2, TiO2, WO3 and ZnO) precursors, two series of AC-metal oxide nanocomposites were prepared by wet impregnation, oven-drying at 120 °C, and subsequent heat treatment at 200 or 850 °C in an inert atmosphere. Here, the electrical conductivity of the resulting products was studied under moderate compression. The influence of the applied pressure, sample volume, mechanical work, and density of the hybrid materials was thoroughly investigated. The DC electrical conductivity of the compressed samples was measured at room temperature by the four-probe method. Compaction assays suggest that the mechanical properties of the nanocomposites are largely determined by the carbon matrix. Both the decrease in volume and the increase in density were relatively small and only significant at pressures lower than 100 kPa for AC and most nanocomposites. In contrast, the bulk electrical conductivity of the hybrid materials was strongly influenced by the intrinsic conductivity, mean crystallite size, content and chemical nature of the supported phases, which ultimately depend on the metal oxide precursor and heat treatment temperature. The supported nanoparticles may be considered to act as electrical switches either hindering or favouring the effective electron transport between the AC cores of neighbouring composite particles in contact under compression. Conductivity values as a rule were lower for the nanocomposites than for the raw AC, all of them falling in the range of semiconductor materials. With the increase in heat treatment temperature, the trend is toward the improvement of conductivity due to the increase in the crystallite size and, in some cases, to the formation of metals in the elemental state and even metal carbides. The patterns of variation of the electrical conductivity with pressure and mechanical work were slightly similar, thus suggesting the predominance of the pressure

Matrix diffusion studies by electrical conductivity methods. Comparison between laboratory and in-situ measurements

International Nuclear Information System (INIS)

Ohlsson, Y.; Neretnieks, I.

1998-01-01

Traditional laboratory diffusion experiments in rock material are time consuming, and quite small samples are generally used. Electrical conductivity measurements, on the other hand, provide a fast means for examining transport properties in rock and allow measurements on larger samples as well. Laboratory measurements using electrical conductivity give results that compare well to those from traditional diffusion experiments. The measurement of the electrical resistivity in the rock surrounding a borehole is a standard method for the detection of water conducting fractures. If these data could be correlated to matrix diffusion properties, in-situ diffusion data from large areas could be obtained. This would be valuable because it would make it possible to obtain data very early in future investigations of potentially suitable sites for a repository. This study compares laboratory electrical conductivity measurements with in-situ resistivity measurements from a borehole at Aespoe. The laboratory samples consist mainly of Aespoe diorite and fine-grained granite and the rock surrounding the borehole of Aespoe diorite, Smaaland granite and fine-grained granite. The comparison shows good agreement between laboratory measurements and in-situ data

The bedrock electrical conductivity structure of Northern Ireland

Science.gov (United States)

Beamish, David

2013-08-01

An airborne geophysical survey of the whole of Northern Ireland has provided over 4.8 M estimates of the bedrock conductivity over the wide range of geological formations present. This study investigates how such data can be used to provide additional knowledge in relation to existing digital geological map information. A by-product of the analysis is a simplification of the spatially aggregated information obtained in such surveys. The methodology used is a GIS-based attribution of the conductivity estimates using a lithological classification of the bedrock formations. A 1:250k geological classification of the data is performed leading to a 56 unit lithological and geostatistical analysis of the conductivity information. The central moments (medians) of the classified data are used to provide a new digital bedrock conductivity map of Northern Ireland with values ranging from 0.32 to 41.36 mS m-1. This baseline map of conductivities displays a strong correspondence with an existing 4 quadrant, chrono-geological description of Northern Ireland. Once defined, the baseline conductivity map allows departures from the norm to be assessed across each specific lithological unit. Bulk electrical conductivity is controlled by a number of petrophysical parameters and it is their variation that is assessed by the procedures employed. The igneous rocks are found to display the largest variability in conductivity values and many of the statistical distributions are multi-modal. A sequence of low-value modes in these data are associated with intrusives within volcanic complexes. These and much older Neoproterzoic rocks appear to represent very low porosity formations that may be the product of rapid cooling during emplacement. By way of contrast, extensive flood basalts (the Antrim lavas) record a well-defined and much higher median value (12.24 mS m-1) although they display complex spatial behaviour in detail. Sedimentary rocks appear to follow the broad behaviours anticipated

Electrical wire as a foreign body in a male urethra: a case report

Directory of Open Access Journals (Sweden)

Stravodimos Konstantinos G

2009-02-01

Full Text Available Abstract Introduction Self-inflicted foreign bodies in the male urethra and urinary bladder are an emergency that urologists may rarely have to face. A case of an electrical wire inserted in the male urethra and coiled in the bladder is presented. Case presentation A 53-year-old male presented with the inability to void and bloody urethral discharge after having introduced an electrical wire in his urethra for masturbation 3 hours earlier. He had made several unsuccessful attempts to remove it. Conclusion The variety of these objects may be impressive and removal of the foreign body may be quite challenging requiring imagination and high-level surgical skills., In this case an electrical wire was used and the diagnostic as well as the therapeutic steps for its removal are presented.

The effect of ZnS thin film's electrical conductivity on electromagnetic ...

African Journals Online (AJOL)

The effect of electrical conductivity on an electromagnetic wave propagating through ZnS thin film is analyzed using electromagnetic wave equation with relevant boundary condition. The solution of this equation enabled us to obtain a parameter known as the skin depth that relates to the conductivity of the thin film. This was ...

Water-dispersible small monodisperse electrically conducting antimony doped tin oxide nanoparticles

Czech Academy of Sciences Publication Activity Database

Peters, K.; Zeller, P.; Štefanić, G.; Skoromets, Volodymyr; Němec, Hynek; Kužel, Petr; Fattakhova-Rohlfing, D.

2015-01-01

Roč. 27, č. 3 (2015), 1090-1099 ISSN 0897-4756 R&D Projects: GA ČR GA13-12386S Grant - others:AVČR(CZ) M100101218 Institutional support: RVO:68378271 Keywords : conducting nanoparticles * electrical conductivity * charge transport Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 9.407, year: 2015

Effect of Aquatic Plants on Phosphorus Removal and Electrical Conductivity Decrease in Municipal Effluent

Directory of Open Access Journals (Sweden)

Sara Samimi Loghmani

2014-05-01

Full Text Available Phosphorus (P is one of essential elements for living organisms, though its critical concentration in surface and ground waters impose a serious problem such as eutrophication. So treatment of polluted waters is required before discharging to water resources. One of effective ways to decrease water pollution is using aquatic plants. An experiment was conducted in pilots with a closed flowing system on two plants, elodea (egria densa and duck weed (lemna minor with four treatments and three replications. Data were analyzed in a factorial completely randomized design. Treatments included effluent with and without the plants, and effluent diluted (dilution grade 1/2 with and without the plants. Total dissolved P, electrical conductivity (EC and pH value were measured after 8, 16 and 24 days in effluent samples. The results showed that pH value decreased up to 0.2 units during of 24 days of the experiment, but there was found no significant difference (p≤0.05 in pH values among the treatments. Both plants decreased EC about 7 % relative to the control (without plant after 24 days. The plants were also effective in reducing total dissolved phosphorus, so that duck weed and elodea decreased total dissolved P in the effluent about 49 and 7%, respectively. It is concluded that duck weed is more effective in the P removal from the effluent than the other plant.

Ionic conductivity, structural deformation, and programmable anisotropy of DNA origami in electric field.