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1

State Electricity Profiles  

NSDL National Science Digital Library

An update to the 1996 State Electricity Profiles, this report from the Energy Information Administration (EIA) is "designed to provide basic information about the electricity industry on a State-by-State basis by profiling each State and the District of Columbia with a description of its electricity industry through graphics, and tables." The data for ten states has been changed, with future updates due in the coming weeks.

2

Electrical resistance of work shoes  

Microsoft Academic Search

ANSI\\/IEEE Std. 80-1986 states that the electrical resistance of shoes is uncertain and that it may be very low for damp leather. Therefore, for purposes of the guide, the electrical resistance of shoes is assumed to be zero. It is believed that the use of zero ohms is unduly conservative for electric utility employees working at job sites where workshoes

J. R. Godlewski; G. T. Purdy; C. J. Blattner

1999-01-01

3

Resistivity Profile in an Urban Setting  

NSDL National Science Digital Library

The student works with an electrical resistivity profile and well information (stratigraphy and static water level)taken in an urban area. The goal is to create an integrated subsurface interpretation from geological and geophysical data. The activity gives students practice in using simple quantitative data to create a hypothetical but data-driven picture of the subsurface. Uses online and/or real-time data Has minimal/no quantitative component Uses geophysics to solve problems in other fields

Montgomery, William

4

Electrical Resistivity Measurements: a Review  

NASA Astrophysics Data System (ADS)

World-wide interest on the use of ceramic materials for aerospace and other advanced engineering applications, has led to the need for inspection techniques capable of detecting unusually electrical and thermal anomalies in these compounds. Modern ceramic materials offer many attractive physical, electrical and mechanical properties for a wide and rapidly growing range of industrial applications; moreover specific use may be made of their electrical resistance, chemical resistance, and thermal barrier properties. In this review, we report the development and various techniques for the resistivity measurement of solid kind of samples.

Singh, Yadunath

5

Electrical Resistivity of Alkali Elements.  

National Technical Information Service (NTIS)

This technical report presents and discusses the available data and information on the electrical resistivity of alkali elements (lithium, sodium, potassium, rubidium, cesium, and francium) and contains recommended reference values (or provisional or typi...

T. C. Chi

1976-01-01

6

State electricity profiles, March 1999  

SciTech Connect

Due to the role electricity plays in the Nation`s economic and social well-being, interested parties have been following the electric power industry`s transition by keeping abreast of the restructuring and deregulation events that are taking place almost daily. Much of the attention centers around the States and how they are restructuring the business of electricity supply within their respective jurisdictions. This report is designed to profile each State and the District of Columbia regarding not only their current restructuring activities, but also their electricity generation and concomitant statistics from 1986 through 1996. Included are data on a number of subject areas including generating capability, generation, revenues, fuel use, capacity factor for nuclear plants, retail sales, and pollutant emissions. Although the Energy Information Administration (EIA) publishes this type of information, there is a lack of a uniform overview for each individual State. This report is intended to help fill that gap and also to serve as a framework for more detailed studies. In addition to basic statistics in tables and graphs, a textual section is provided for each State, discussing some of the points relative to electricity production that are noteworthy in, or unique to, that particular State. Also, each State is ranked according to the place it holds, as compared to the rest of the states, in various relevant areas, such as its average price of electricity per kilowatthour, its population, and its emissions of certain atmospheric pollutants. The final chapter covers the Nation as a whole. 451 figs., 520 tabs.

NONE

1999-03-01

7

Molecular Expressions: Electricity & Magnetism: Resistance  

NSDL National Science Digital Library

Comprehensive tutorial on resistance, accompanied by three interactive simulations. One allows the user to glimpse resistance at a molecular level; the second explores Ohm's Law; and the third introduces the use of color coding in composition resistors. The author uses diagrams to illustrate arrangements of resistors in series and parallel circuits, with explanations of how to calculate equivalent resistances. This item is part of a larger collection on Electricity and Magnetism sponsored by Florida State University..

Davidson, Michael

8

The electrical resistance of vacuum  

NASA Astrophysics Data System (ADS)

This paper deals with the physics of electrical conduction in vacuum between two parallel conducting planes (planar vacuum diode). After reviewing known features of conduction in the high-voltage range, we turn to the low-voltage range. An ohmic current-voltage characteristic is calculated in the case of identical cathodic and anodic electrodes, whence an electrical resistance of the vacuum gap can be defined. The inverse resistance involves the elemental conductance 2e 2/h and the number of conductance channels between the two electrodes. The channels are thermally populated from the electrodes and the population is analytically calculable from the Poisson equation of electrostatics and the Boltzmann law of thermal equilibrium. The observed resistance of a real vacuum diode (Mullard's EB 91) is accounted for without adjusting parameters. The paper also examines the link-up between Joule's law, involving dissipation, and Ohm's law, with vacuum being contrasted with a material conducting medium; the origin of dissipation in vacuum is understood. Quantum and statistical physics are kept at the undergraduate level. Finally, the results obtained for the vacuum diode shed light upon the quantized conductance of nanoscale semiconductor wires, a topic usually handled only in graduate courses.

Bringuier, E.

2013-07-01

9

Electrical resistivity survey in eastern Jeju Island  

NASA Astrophysics Data System (ADS)

Electrical resistivity survey was conducted to acquire basic geological layer information for regional hydrogeologic application by our own developed system in eastern Jeju island. The system mainly consists of a stand-alone TX(transmitter) module, of which the excitation current into the earth has been increased very much using a portable AC generator instead of batteries, a digital stacking RX(receiver), and a pair of programmable synchronization clock modules to achieve the initial synchronization between TX and RX. The waveform of the excitation current into the earth at transmitter side is double bipolar, and the power is 1000V-1A or 800V-5A with a portable AC generator. At the receiver part controlled through a notebook PC's serial port, the operator can observe the exact waveform and the averaged value with 24-bit A/D resolution and gain 1-10-100. The small portable synchronization clocks, operated by 12V/2A sealed battery, provides the precise basic measurement cycles and initial triggering. The control and measurement software which acquires the earth resistivity data was developed user-interactively. The system was field-tested in eastern part of Jeju Island with dipole spacing a=300m and 600m, to n=10, and stations=43, by the array of which the exploration depth has been increased to about 2,400 m. By the developed portable system we could conduct very easy and fast field work and acquire very satisfactory data. The inversion of measured data gave us the useful information about the sub-surface resistivity structure to about 2,400 m depth along a 13km survey profile. Further study will be focused on simultaneous multi receiver data acquisition system.

Jung, H.

2010-12-01

10

Electrical Resistance Measurement of Conductive Flooring.  

National Technical Information Service (NTIS)

Methods for measuring the electrical resistance of conductive flooring at hospitals and ordnance activities are discussed. It is recommended that the method of the National Fire Protection Association Standard 56A be used, with minor modifications, for al...

P. J. Hearst

1973-01-01

11

Electrical resistivity of a titanium powder mass  

Microsoft Academic Search

In this paper, the variation with the porosity of the electrical resistivity of a compressed powder mass of commercially pure\\u000a titanium has been studied. The study has been carried out via the direct measurement of the electrical resistance of a powder\\u000a column subjected to uniaxial compression. The obtained experimental data have been fit to a theoretical model, proposed by\\u000a the

J. M. Montes; F. G. Cuevas; J. Cintas

2011-01-01

12

Electrical Resistivity of Metal Powder Aggregates  

Microsoft Academic Search

An equation for calculating the electrical resistivity of a compressed powder mass, consisting of oxide-coated metal particles, has been derived. In addition to the intrinsic interest of the problem, the proposed equation is useful for describing the very early stages of electrical sintering processes. The problem is approached in a new way, relating the actual powder system to an equivalent

J. M. Montes; F. G. Cuevas; J. Cintas

2007-01-01

13

Electrical Resistivity of Metal Powder Aggregates  

NASA Astrophysics Data System (ADS)

An equation for calculating the electrical resistivity of a compressed powder mass, consisting of oxide-coated metal particles, has been derived. In addition to the intrinsic interest of the problem, the proposed equation is useful for describing the very early stages of electrical sintering processes. The problem is approached in a new way, relating the actual powder system to an equivalent system consisting of deforming spheres in a simple cubic packing, which is much easier to examine. The proposed equation was experimentally verified from measurements of the electrical resistivity for aluminum, bronze, iron, and nickel powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases.

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

2007-12-01

14

Fabrication and Characterization of Electric Field - Induced Resistive Sensor at the end of Scanning Probe Tip.  

National Technical Information Service (NTIS)

Fabrication and Characterization of Electrical Field were investigated to develop induced Resistive Sensor at the end of Scanning Probe Tip. The measurement and visual observation of doping profile were performed on Kelvin Prove Force Microscopy (KPFM) & ...

H. Shin

2006-01-01

15

Improvement of resist profile roughness in bilayer resist process  

NASA Astrophysics Data System (ADS)

The bi-layer resist (BLR) process, which first accomplish imaging on a thin top layer and transfer it down to a thick organic layer, is one of newly emerging patterning techniques in silicon processing. In this work, we studied the lithographic performance of the BLR process adopting FK- SPTM (Fujifilm Olin Co.) as top layer material and various organic material as bottom layer. Generally, considerable advantages of planarization, reduced substrate reflection, improved process latitude, and of enhanced resolution are achieved. However, the resolution and the process latitude are highly affected by surface interaction between the top resist and the bottom material. Moreover, the BLR process has a sidewall roughness problem related to the material factors of the resist and the degraded aerial image contrast, which can affect the reliability of the device. We found that thermal curing treatment applied after development with the consideration of the glass transition temperature are very effective in reducing the line edge roughness. More smooth and steep patterning is achieved by the thermal treatment. The linewidth controllability is below 10 nm and the k1 value is reduced from 0.5 down to 0.32 in this process. The reactive ion etching adopting O2 gas demonstrated selectivity of the top resist over bottom material more than 15:1, together with residue-free and vertical wall profile.

Jeong, Chang Young; Ryu, Sang-Wook; Park, Ki-Yeop; Lee, Won-Kyu; Lee, Seung-Woog; Lee, Dai-Hoon

2000-06-01

16

A MICROSCOPIC ANALYSIS ON THE ELECTRICAL PULSE INDUCED RESISTANCE CHANGE EFFECT  

Microsoft Academic Search

We have carried out microscopic resistance profile measurements by scanning probe microscopy (SPM) and model analyses on a symmetric thin-film electrical pulse induced resistance change (EPIR) device having a Pr0.7Ca0.3MnO3(PCMO) active layer. The film morphology and surface potential distribution has been examined by atomic force microscopy (AFM) and surface scanning Kelvin probe microscopy (SKPM). Resistance distribution profiles across the device

X. CHEN; N. J. WU; J. STROZIER; A. IGNATIEV

2007-01-01

17

Resistance after firing protected electric match  

DOEpatents

An electric match having electrical leads embedded in flame-producing compound is protected against an accidental resistance across the leads after firing by a length of heat-shrinkable tubing encircling the match body and having a skirt portion extending beyond the leads. The heat of the burning match and an adjacent thermal battery causes the tubing to fold over the end of the match body, covering the ends of the leads and protecting them from molten pieces of the battery.

Montoya, Arsenio P. (Albuquerque, NM)

1981-11-10

18

Electrical Resistivity of Metal Powder Aggregates  

Microsoft Academic Search

An equation for calculating the electrical resistivity of a compressed powder mass, consisting of oxide-coated metal particles,\\u000a has been derived. In addition to the intrinsic interest of the problem, the proposed equation is useful for describing the\\u000a very early stages of electrical sintering processes. The problem is approached in a new way, relating the actual powder system\\u000a to an equivalent

J. M. Montes; F. G. Cuevas; J. Cintas

2007-01-01

19

Pedotransfer functions in soil electrical resistivity estimation  

Technology Transfer Automated Retrieval System (TEKTRAN)

Surface electrical resistivity tomography (ERT) is recognized as a powerful non-invasive soil survey and monitoring method. Relationships between ER and soil water contents that are needed to infer the spatial distribution of soil moisture from the ERT results, are known to reflect soil properties. ...

20

The Electrical Potential Profile of the Isolated Toad Bladder  

PubMed Central

The electrical potential profile of the isolated toad bladder was examined in the spontaneously active, chronically short-circuited, and intermittently short-circuited states by means of glass micropipettes. The position of the micropipette tip within the bladder was evaluated by measuring the D.C. resistance between the micropipette tip and the reference electrode on the serosal side of the bladder. In the spontaneously active state, with concentrations of sodium in the mucosal solution ranging from less than 1 to 114 meq per liter, the potential profile consisted in the majority of impalements of two steps, each positive to the mucosal solution. A minority of impalements showed more than two potential steps, each positive to the mucosal solution. In the short-circuited state, the interior of the bladder was found to be negative to the bathing solution by approximately 5 mv. The results are interpreted as showing a potential step at the two surfaces of the epithelial cell layer of the toad bladder. In the spontaneously active state the potential change at the mucosal boundary is of the wrong polarity to bring about net sodium entry; the small electrical driving force across the mucosal surface which is present in the short-circuited state may contribute to the net entry of sodium from mucosal solutions with low sodium concentration.

Frazier, Howard S.

1962-01-01

21

Estimating soil suction from electrical resistivity  

NASA Astrophysics Data System (ADS)

Soil suction and resistivity strongly depend on the degree of soil saturation and, therefore, both are used for estimating water content variations. The main difference between them is that soil suction is measured using tensiometers, which give point information, while resistivity is obtained by tomography surveys, which provide distributions of resistivity values in large volumes, although with less accuracy. In this paper, we have related soil suction to electrical resistivity with the aim of obtaining information about soil suction changes in large volumes, and not only for small areas around soil suction probes. We derived analytical relationships between soil matric suction and electrical resistivity by combining the empirical laws of van Genuchten and Archie. The obtained relationships were used to evaluate maps of soil suction values in different ashy layers originating in the explosive activity of the Mt Somma-Vesuvius volcano (southern Italy). Our findings provided a further example of the high potential of geophysical methods in contributing to more effective monitoring of soil stress conditions; this is of primary importance in areas where rainfall-induced landslides occur periodically.

Piegari, E.; Di Maio, R.

2013-09-01

22

Vertical profiles of atmospheric electric parameters close to ground  

Microsoft Academic Search

The ion-aerosol balance equations have been solved for different mixing strengths and two types of ionization profile to get vertical profiles of atmospheric electric parameters close to the Earth's surface. The inclusion of surface radioactivity in the model causes the decrease in electric field to be more intense at lower levels than at higher levels, an increase in the asymptotic

Madhuri Kulkarni; A. K. Kamra

2001-01-01

23

Electrical resistivity of Ni - In liquid alloys  

NASA Astrophysics Data System (ADS)

The electrical resistivity of liquid 0953-8984/9/46/009/img1 alloys has been measured as a function of temperature (between the melting point and 0953-8984/9/46/009/img2) and of concentration in 10 at.% steps over the whole phase diagram. The concentration dependence of the resistivity shows a maximum at about 60 at.% nickel. In the neighbourhood of this concentration, the temperature dependence 0953-8984/9/46/009/img3 changes sign. We have interpreted semi-quantitatively our experimental results using the extended Faber - Ziman theory within the t matrix formalism.

Rhazi, A.; Auchet, J.; Gasser, J. G.

1997-11-01

24

Electrical resistance tomography of concrete structures  

SciTech Connect

The purpose of this work is to determine the feasibility of using Electrical resistance tomography (ERT) to nondestructively examine the interior of concrete structures such as bridge pillars and roadways. We report the results of experiments wherein ERT is used to image the two concrete specimens in the laboratory. Each specimen is 5 inches square and 12 inches long and contained steel reinforcing rods along its length. Twenty electrodes were placed on each sample and an-image of electrical resistivity distribution was generated from current and voltage measurements. We found that the images show the general location of the reinforcing steel and, what`s more important, delineate the absence of the steel. The method may therefore be useful for determining if such steel has been destroyed by corrosion, however to make it useful, the technique must have better resolution so that individual reinforcing steel units are resolved.

Daily, W.; Ramirez, A. [Lawrence Livermore National Lab., CA (United States); Binley, A.; Henry-Poulter, S. [Lancaster Univ. (United Kingdom). Dept. of Environmental Sciences

1993-10-01

25

Load profiling and data mining techniques in electricity deregulated market  

Microsoft Academic Search

This paper presents load profiles of electricity customers, using the knowledge discovery in databases (KDD) procedure, a data mining technique, to determine the load profiles for different types of customers. In this paper, the current load profiling methods are compared using data mining techniques, by analysing and evaluating these classification techniques. The objective of this study is to determine the

A. H. Nizar; Z. Y. Dong; J. H. Zhao

2006-01-01

26

An introduction to electrical resistivity in geophysics  

NASA Astrophysics Data System (ADS)

Physicists are finding that the skills they have learned in their training may be applied to areas beyond traditional physics topics. One such field is that of geophysics. This paper presents the electrical resistivity component of an undergraduate geophysics course at Radford University. It is taught from a physics perspective, yet the application of the theory to the real world is the overriding goal. The concepts involved in electrical resistivity studies are first discussed in a general sense, and then they are studied through the application of the relevant electromagnetic theory. Since geology majors comprise the bulk of the students in this class, the math used is only that which is typically required of geology majors. The final results are given in a form that practicing geophysicists may use in the field. A method is presented for constructing an inexpensive apparatus for measuring electrical resistivity in both a tabletop laboratory setting and in the field. This apparatus is truly ``plug and play'' since its assembly and use requires only the most basic knowledge of electronics. This apparatus is tested in a tabletop laboratory setting as well as in two field surveys.

Herman, Rhett

2001-09-01

27

Using electrical resistance tomography to map subsurface temperatures  

Microsoft Academic Search

A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and\\/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass\\/rock mass. Tomographs of electrical resistivity are calculated based on the

Abelardo L. Ramirez; Dwayne A. Chesnut; William D. Daily

1994-01-01

28

Complex Electrical Resistivity for Monitoring DNAPL Contamination  

SciTech Connect

Nearly all Department of Energy (DOE) facilities have landfills and buried waste areas. Of the various contaminants present at these sites, dense non-aqueous phase liquids (DNAPL) are particularly hard to locate and remove. There is an increasing need for external or non-invasive sensing techniques to locate DNAPLs in the subsurface and to track their spread and monitor their breakdown or removal by natural or engineered means. G. Olhoeft and colleagues have published several reports based on laboratory studies using the complex resistivity method which indicate that organic solvents, notably toluene, PCE, and TCE, residing in clay-bearing soils have distinctive electrical signatures. These results have suggested to many researchers the basis of an ideal new measurement technique for geophysical characterization of DNAPL pollution. Encouraged by these results we proposed to bring the field measurement of complex resistivity as a means of pollution characterization from the conceptual stage to practice. We planned to document the detectability of clay-organic solvent interactions with geophysical measurements in the laboratory, develop further understanding of the underlying physical and chemical mechanisms, and then apply these observations to develop field techniques. As with any new research endeavor we note the extreme importance of trying to reproduce the work of previous researchers to ensure that any effects observed are due to the physical phenomena occurring in the specimen and not due to the particular experimental apparatus or method used. To this end, we independently designed and built a laboratory system, including a sample holder, electrodes, electronics, and data analysis software, for the measurement of the complex electrical resistivity properties of soil contaminated with organic solvents. The capabilities and reliability of this technique were documented. Using various standards we performed measurement accuracy, repeatability, and noise immunity tests of this system and we were able to reproduce some key complex resistivity effects quoted in the literature. We attempted numerous times to reproduce the seminal results of Olhoeft and Sadowski on the complex resistivity response of toluene-contaminated clay-rich samples. While we observe similar responses to theirs for plain clays with brine, the addition of toluene does not produce the effects they claimed. We can only produce effects of similar magnitude if we intentionally introduce a large artificial dielectric heterogeneity in the specimen. We have also performed laboratory studies to test the sensitivity of the complex resistivity method to toluene and methanol contamination in sands, clays, and rocks. Additionally, we performed 4-wire IP inversion measurements in a two-dimensional laboratory 'ant farm' to test the ability of this technique to image materials with both conductivity and dielectric heterogeneities. This work indicates, at best, a low sensitivity of the complex electrical resistivity method to organic contamination in rocks and soils. This reduces the short-term prospects of using complex resistivity as an effective technique to directly detect organic contamination. However, as noise suppression techniques improve and further understanding of electrical responses in Earth materials is achieved, the potential of the complex resistivity technique should improve. In contrast, we find that certain electrically polarizing materials, some clays for example, have responses large enough compared to sandy and silty soils to be reliably imaged through a detailed field IP survey. Thus, quantifying soil heterogeneity (which may relate to DNAPL distribution and transport) is an immediate potential application of this technique.

Stephen R. Brown; David Lesmes; John Fourkas

2003-09-12

29

Cone-based electrical resistivity tomography  

NASA Astrophysics Data System (ADS)

Determining the 3-D spatial distribution of subsurface properties is a critical part of managing the clean-up of contaminated sites. Most standard hydrologic methods sample small regions immediately adjacent to wells or testing devices. This provides data which are not representative of the entire region of interest. Furthermore, at many contaminated sites invasive methods are not acceptable, due to the risks associated with contacting and spreading the contaminants. To address these issues, I have developed a minimally invasive technology that provides information about the 3-D distribution of electrical conductivity. This new technique, cone-based electrical resistivity tomography (C-bert), integrates the existing technologies of resistivity cone penetration testing (RCPT) with electrical resistivity tomography. Development of this tool included the creation of new software and modeling algorithms, the design of field equipment, field testing, and processing and interpretation of the resulting data. I present a 2.5-D forward modeling algorithm that incorporates an effective correction for the errors caused by boundary effects and source singularities. The algorithm includes an optimization technique for acquiring the Fourier coefficients required for the solution. A 3-D inversion algorithm is presented that has two major improvements over existing algorithms. First, it includes a 3-D version of the boundary correction/source singularity correction developed for the 2.5-D problem. Second, the algorithm can handle any type of acquisition geometry; this was a requirement for the development of C-bert. C-bert involves placing several permanent current electrodes in the subsurface and using electrodes mounted on a cone penetrometer and at the surface to measure the resultant potential field. In addition to these measurements, we obtain the standard suite of RCPT data, including high resolution resistivity logs. The RCPT data can be used to generate a realistic starting model for the inversion. Furthermore, the resistivity logs can be used as constraints in the inversion of the potential field data. Effective incorporation of resistivity logs into the inversion process, however, requires an understanding the spatial averaging that occurs during logging. I developed a forward modeling and inversion algorithm that allows us to understand and remove the averaging that is present in the logs. A successful field test of C-bert was conducted at the Kidd2 site in Richmond, British Columbia, leading me to conclude that C-bert is a promising new way to image the subsurface.

Pidlisecky, Adam

30

Electrical Resistance Tomography imaging of concrete  

SciTech Connect

We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete.

Karhunen, Kimmo [Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio (Finland); Seppaenen, Aku, E-mail: Aku.Seppanen@uku.f [Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio (Finland); Lehikoinen, Anssi [Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio (Finland); Monteiro, Paulo J.M. [Department of Civil and Environmental Engineering, University of California Berkeley, California (United States); Kaipio, Jari P. [Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio (Finland); Department of Mathematics, University of Auckland, Auckland (New Zealand)

2010-01-15

31

Tank leak detection using electrical resistance methods  

SciTech Connect

Large volumes of hazardous liquids and high-level radioactive wastes are stored worldwide in surface and underground tanks. Frequently these tanks are found to leak, thereby resulting in not only a loss of stored inventory, but in contamination to soils and groundwater. It is important to develop a reliable method of detecting leaks before large quantities are emitted into the environment surround the tanks. Two field experiments were performed to evaluate the performance of electrical resistance tomography (ERT) as a leak detection method under metal underground storage tanks (UST). This paper provides a summary of the field experiments performed under a 15 m diameter steel tank mockup located at the Hanford Reservation.

Ramirez, A.; Daily, W.; Binley, A.; LaBrecque, D.

1996-01-01

32

Complex Electrical Resistivity from Monitoring DNAPL Contamination  

SciTech Connect

Nearly all Department of Energy (DOE) facilities have landfills and buried waste areas. Of the various contaminants present at these sites, dense non-aqueous phase liquids (DNAPL) are particularly hard to locate and remove. There is an increasing need for external or non-invasive sensing techniques to locate DNAPLs in the subsurface and to track their spread and monitor their breakdown or removal by natural or engineered means. G. Olhoeft and colleagues have published several reports based on laboratory studies indicating that strong electrical signatures are produced when organic solvents, notably toluene, PCE, and TCE, reside in clay-bearing soils. According to Olhoeft, these electrical signatures are apparently characteristic of and unique to the particular organic solvent involved. The experiments are performed by packing the contaminated soil in a sample holder and a 4-electrode complex electrical resistivity measurement is made, where two of the electrodes are used to impose a sinusoidal electric current and the remaining two electrodes are used to sense the response voltage of the specimen. The relative phase (or time delay) between the source and the response signals at low excitation frequencies is a particularly sensitive measure of electrochemical processes occurring within the specimen. This suggests the basis of an ideal new measurement technique for geophysical characterization of NAPL pollution. Despite the promising laboratory results, attempts to measure these effects in the field for characterizing polluted sites, including studies supported by DOE funding, seldom have been successful. Encouraged by the aforementioned laboratory results we had proposed to bring the field measurement of complex resistivity as a means of pollution characterization from the conceptual stage to practice. For this purpose we intend to document the detectability of clay-organic interactions with geophysical measurements in the laboratory, develop further understanding of the underlying physical and chemical mechanisms, and then apply these observations to develop field techniques to monitor the remediation of organic pollutants. Research Progress

Brown, Stephen R.

2003-06-01

33

Electrical profiling of collector and base doping concentration  

Microsoft Academic Search

A method for electrically profiling the collector carrier density of a bipolar device is reported. The base doping profile is also obtainable. This measurement technique is also useful in monitoring epi thickness and base width. The measurements are simple, economical, and accurate

T.-Y. Chiu; J. J. Sung; J. Pavlo; T.-Y. M. Liu; K. F. Lee; W. Possanza; K. Moerschel

1991-01-01

34

Electrical resistance of superconducting cable splices  

SciTech Connect

The electrical resistance of superconducting cable splices is known to be in the 10{sup -9} {Omega} range which to be measured conventionally would require the use of a micro voltmeter with a power supply capable of generating kilo Amperes plus a liquid helium cryostat with large power leads. Here we present a system for carrying on such measurements that requires besides the microvoltmeter a power supply capable of generating only up to 35 {Alpha} and a 152 mm diameter neck helium dewar using less than 25 liters per day after initial cool down. In this paper we describe the apparatus and present the data taken with it in its first use which for data acquisition used just a chart recorder. The method is based in making the splice in a loop of cable, inducing a current in it and measuring its decay time constant. Generating high currents in superconductors by induction is not a new technique but the use of the decay constant of currents generated this way for the determination of minute electrical resistance seems novel to the author. Unexpected details in the results will be discussed.

Kuchnir, M.

1997-07-01

35

Acquisition of electrical resistivity data. Application to soil moisture content  

Microsoft Academic Search

Geophysical investigation such as detecting electrical resistivity or conductivity of soil has been applied in other to seek correlations between soil properties and soil state. There may be a lot of reasons for variation of the electrical soil apparent resistivity (bulk density, hydraulic conductivity, pore distribution, porosity), but in the same type of non polluted soil, the changes of electrical

Florina Chitea

2010-01-01

36

Resistance and dopant profiling along freestanding GaAs nanowires  

NASA Astrophysics Data System (ADS)

Resistance profiles along as-grown GaAs nanowires were measured with a multi-tip scanning tunneling microscope used as a nanoprober. The nanowires were grown in the vapor-liquid-solid growth mode in a two-temperature-step mode and doped with Zn. Using a transport model, the resistance profile was converted to a dopant profile. The dopant distribution along the nanowires was found to correlate with the temperature during different phases of nanowire growth. The nanowire base grown at higher temperature exhibits a decreased dopant concentration. Mechanical stress by intentional bending of a nanowire was shown not to influence nanowire conductance.

Korte, Stefan; Steidl, Matthias; Prost, Werner; Cherepanov, Vasily; Voigtländer, Bert; Zhao, Weihong; Kleinschmidt, Peter; Hannappel, Thomas

2013-09-01

37

Electrical resistance of a fluidized bed of graphite particles  

Microsoft Academic Search

Experimental data on the electrical resistivity of fluidized beds of graphite particles are given. The dependence of the resistivity on the filtration velocity, particle size, temperature of the bed, and position of the electrodes is determined.

A. P. Kozhan; K. E. Makhorin; S. P. Gorislavets

1968-01-01

38

Profiles of America's leading renewable electricity developers  

Microsoft Academic Search

While the nuclear power industry has been struggling with widely publicized economic and regulatory snafus as well as the fallout of the Chernobyl nuclear accident, the renewable energy industry has continued to evolve - largely without fanfare. Capable of producing electricity from a variety of sources ranging from the wind to garbage, the renewable industry holds commercially viable alternatives to

2009-01-01

39

The electrical resistivity method in cased boreholes  

SciTech Connect

The use of downhole current sources in resistivity mapping can greatly enhance the detection and delineation of subsurface features. The purpose of this work is to examine the resistivity method for current sources in wells cased with steel. The resistivity method in cased boreholes with downhole current sources is investigated using the integral equation (IE) technique. The casing and other bodies are characterized as conductivity inhomogeneities in a half-space. For sources located along the casing axis, an axially symmetric Green's function is used to formulate the surface potential and electric field (E-field) volume integral equations. The situations involving off-axis current sources and three-dimensional (3-D) bodies is formulated using the surface potential IE method. The solution of the 3-D Green's function is presented in cylindrical and Cartesian coordinate systems. The methods of moments is used to solve the Fredholm integral equation of the second kind for the response due to the casing and other bodies. The numerical analysis revealed that the current in the casing can be approximated by its vertical component except near the source and the axial symmetric approximation of the casing is valid even for the 3-D problem. The E-field volume IE method is an effective and efficient technique to simulate the response of the casing in a half-space, whereas the surface potential approach is computationally better when multiple bodies are involved. Analyzing several configurations of the current source indicated that the casing response is influenced by four characteristic factors: conduction length, current source depth,casing depth, and casing length. 85 refs., 133 figs., 11 tabs.

Schenkel, C.J.

1991-05-01

40

Field-reversed configuration profiles and resistivities inferred from the radial line-integral density profile  

Microsoft Academic Search

The beta and magnetic field profiles of field-reversed configurations (FRC’s) can be inferred from the radial profile of the line-integral density together with a temperature model. When these profiles are combined with the particle and flux decay times, the plasma resistivities at the field null and separatrix can also be deduced. This method is applied to a class of FRC’s

R. E. Chrien; S. Okada

1987-01-01

41

Viscosity and electrical resistivity of Al-Li melts  

NASA Astrophysics Data System (ADS)

The kinematic viscosity and electrical resistivity of Al-Li alloys in the liquid state are studied by a combined electrodeless method. Some theoretical calculations performed to determine the viscosity and electrical resistance by comparing the calculated and experimental data are estimated.

Kononenko, V. I.; Razhabov, A. A.; Ryabina, A. V.

2011-08-01

42

Damage detection in carbon fiber composites using electrical resistance measurements  

NASA Astrophysics Data System (ADS)

This thesis proposes a methodology for structural health monitoring that incorporates the inherent multi-functionality of carbon fibers. The hypothesis of the thesis is that by monitoring the electrical resistance of composite panels it is possible to detect impacts and statistically model their effects on the remaining useful service life of structures. The proposed research investigates the application of statistics-based analysis to the measured electrical resistance signals during loading. The research also investigates the use of electrical resistance as a stress sensor by monitoring the resistance of test samples under tensile loading.

Gory, Ryan

43

Students’ understanding of direct current resistive electrical circuits  

Microsoft Academic Search

Research has shown that both high school and university students' reasoning\\u000apatterns regarding direct current resistive electric circuits often differ from\\u000athe currently accepted explanations. At present, there are no standard\\u000adiagnostic examinations in electric circuits. Two versions of a diagnostic\\u000ainstrument called Determining and Interpreting Resistive Electric circuits\\u000aConcepts Tests (DIRECT) were developed, each consisting of 29 questions. The

Paula Vetter Engelhardta; Robert J. Beichner

2004-01-01

44

ELECTRICAL RESISTIVITY OF STABILIZED ZIRCONIA AT ELEVATED TEMPERATURES  

Microsoft Academic Search

The electric resistivity of stabilized zirconia of various compositions ; was measured by a four-probe technique in the temperature range 550 to 1200 deg ; C. Resistivities of fully stabilized compositions were found to increase with ; increasing additions of the stabilizing oxide, and the lowest resistivities ; appear to occur in materials stabilized with small cations. (auth);

J. M. Dixon; L. D. LaGrange; U. Merten; C. F. Miller; J. T. Jr. Porter

1963-01-01

45

Transient current electric field profiling of single crystal CVD diamond  

NASA Astrophysics Data System (ADS)

The transient current technique (TCT) has been adapted for profiling of the electric field distribution in intrinsic single crystal CVD diamond. It was found that successive hole transits do not appreciably affect the electric field distribution within the sample. Transits of holes can therefore be used to probe the electric field distribution and also the distribution of trapped charge. Electron transits, on the other hand, cause an accumulation of negative charge in the sample. Illumination with blue or green light was shown to lead to accumulation of positive charge. Low concentrations of trapped charge can be detected in diamond using TCT, corresponding to an ionized impurity concentration below N = 1010 cm-3.

Isberg, J.; Gabrysch, M.; Tajani, A.; Twitchen, D. J.

2006-08-01

46

Psychological Profile of Survival, Evasion, Resistance and Escape Instructor Personnel.  

National Technical Information Service (NTIS)

The Psychological Profile of Navy Survival, Evasion, Resistance, and Escape (SERE) Instructor Personnel is critical to the success of this type of training. Sixty-four SERE instructors were administered a clinical interview; the Shipley, MMPI-2, NEO PI-R,...

J. M. Govia

1994-01-01

47

Iron aluminide useful as electrical resistance heating elements  

SciTech Connect

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {le}1% Cr and either {ge}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {ge}0.1% oxide dispersoid particles. The alloy can contain 14--32% Al, {le}2% Ti, {le}2% Mo, {le}1% Zr, {le}1% C, {le}0.1% B, {le}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {le}1% rare earth metal, {le}1% oxygen, {le}3% Cu, balance Fe.

Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

1999-11-02

48

Sinkhole detection using electrical resistivity tomography in Saudi Arabia  

NASA Astrophysics Data System (ADS)

Karst phenomena exist in different areas in the Kingdom of Saudi Arabia, causing serious environmental problems that affect urban development and infrastructure (buildings, roads and highways). One of the most important problems are sinkholes, which most of the time consist of unfilled voids. These sinkholes are formed as a result of the chemical leaching of carbonate and evaporite formations by percolating water. Field investigations show that there are many surface expressions of sinkholes in the area; some appear on the ground surface and others are hidden in the subsurface. Geophysical data were collected at the study area using two-dimensional electrical resistivity tomography (ERT) with different electrode spacings to delineate buried sinkholes and associated subsurface cavities. Our findings indicated that the dipole-dipole method using an electrode spacing of 1 m was successful in detecting a known subsurface sinkhole. According to the ERT method the detected sinkhole depth ranges from 2 to 4 m, its height ranges from 2 to 4 m, and its width ranges from 5 to 7 m. Field observation has verified the geophysical data, especially along the profile A-A\\. Finally, closely spaced ERT profiles were successful in determining the three-dimensional volume of the subsurface sinkhole.

Youssef, Ahmed M.; El-Kaliouby, Hesham; Zabramawi, Yasser A.

2012-12-01

49

Resistance Profiles of Novel Electrostatically Constrained HIV-1 Fusion Inhibitors*  

PubMed Central

Human immunodeficiency virus (HIV) gp41 plays a key role in viral fusion; the N- and C-terminal heptad repeats (N-HR and C-HR) of gp41 form a stable 6-helical conformation for fusion. Therefore, HR-derived peptides, such as enfuvirtide (T-20), inhibit HIV-1 fusion by acting as decoys, and have been used for the treatment of HIV-1 infection. However, the efficacy of T-20 is attenuated by resistance mutations in gp41, including V38A and N43D. To suppress the resistant variants, we previously developed electrostatically constrained peptides, SC34 and SC34EK, and showed that both exhibited potent anti-HIV-1 activity against wild-type and T-20-resistant variants. In this study, to clarify the resistance mechanism to this next generation of fusion inhibitors, we selected variants with resistance to SC34 and SC34EK in vitro. The resistant variants had multiple mutations in gp41. All of these mutations individually caused less than 6-fold resistance to SC34 and SC34EK, indicating that there is a significant genetic barrier for high-level resistance. Cross-resistance to SC34 and SC34EK was reduced by a simple difference in the polarity of two intramolecular electrostatic pairs. Furthermore, the selected mutations enhanced the physicochemical interactions with N-HR variants and restored activities of the parental peptide, C34, even to resistant variants. These results demonstrate that our approach of designing gp41-binding inhibitors using electrostatic constraints and information derived from resistance studies produces inhibitors with enhanced activity, high genetic barrier, and distinct resistance profile from T-20 and other inhibitors. Hence, this is a promising approach for the design of future generation peptide fusion inhibitors.

Shimura, Kazuya; Nameki, Daisuke; Kajiwara, Keiko; Watanabe, Kentaro; Sakagami, Yasuko; Oishi, Shinya; Fujii, Nobutaka; Matsuoka, Masao; Sarafianos, Stefan G.; Kodama, Eiichi N.

2010-01-01

50

Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes  

SciTech Connect

A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950 deg. C. The lowest resistances were obtained mainly from MWNTs grown at 900 deg. C. The MWNT resistance is larger on average at lower (800 deg. C) and higher (950 deg. C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907 and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Department of Physics, Purdue University, West Lafayette, Indiana 47907 and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)

2007-08-27

51

Antibiotic resistant bacterial profiles of anaerobic swine lagoon effluent.  

PubMed

Although land application of swine (Sus scrofa) manure lagoon effluent is a common and effective method of disposal, the presence of antibiotic-resistant bacteria, both pathogenic and commensal can complicate already understood issues associated with its safe disposal. The aim of this study was to assess antibiotic resistance in swine lagoon bacteria from sow, nursery, and finisher farms in the southeastern United States. Effluents from 37 lagoons were assayed for the presence of Escherichia coli, Campylobacter, Listeria, and Salmonella. Antibiotic resistance profiles were determined by the Kirby-Bauer swab method for 12 antibiotics comprising eight classes. Statistical analyses indicated that farm type influenced the amount and type of resistance, with nurseries and sow farms ranking as most influential, perhaps due to use of more antibiotic treatments. Finisher farms tended to have the least amount of antibiotic class resistance, signaling an overall healthier market pig, and less therapeutic or prophylactic antibiotic use. Many bacterial isolates were resistant to penicillin, cephalosporin, and tetracycline class antibiotics, while nearly all were susceptible to quinolone antibiotics. It appeared that swine farm type had a significant association with the amount of resistance associated with bacterial genera sampled from the lagoons; nurseries contributed the largest amount of bacterial resistance. PMID:19875799

Brooks, J P; McLaughlin, M R

2009-10-29

52

Control of the Electric Field Profile in the Hall Thruster  

SciTech Connect

Control of the electric field profile in the Hall Thruster through the positioning of an additional electrode along the channel is shown theoretically to enhance the efficiency. The reduction of the potential drop near the anode by use of the additional electrode increases the plasma density there, through the increase of the electron and ion transit times, causing the ionization in the vicinity of the anode to increase. The resulting separation of the ionization and acceleration regions increases the propellant and energy utilizations. An abrupt sonic transition is forced to occur at the axial location of the additional electrode, accompanied by the generation of a large (theoretically infinite) electric field. This ability to generate a large electric field at a specific location along the channel, in addition to the ability to specify the electric potential there, allows one further control of the electric field profile in the thruster. In particular, when the electron temperature is high, a large abrupt voltage drop is induced at the vicinity of the additional electrode, a voltage drop that can comprise a significant part of the applied voltage.

A. Fruchtman; N. J. Fisch; Y. Raitses

2000-10-05

53

Electrical resistivity tomography at the DOE Hanford site.  

National Technical Information Service (NTIS)

Recent work at the DOE Hanford site has established the potential of applying Electrical Resistivity Tomography (ERT) for early leak detection under hazardous waste storage facilities. Several studies have been concluded to test the capabilities and limit...

S. M. Narbutovskih T. D. Halter M. D. Sweeney W. Daily A. L. Ramirez

1996-01-01

54

Electrical Resistivity Imaging to Quantify Spatial Soil Heterogeneity  

NASA Astrophysics Data System (ADS)

Electrical resistivity (ER) sounding is increasingly being used as non-invasive technique to reveal and map soil heterogeneity. The objective of this work was to evaluate effects of soil properties on the electric resistivity and to observe these effects in spatial context in coarse-textured soil. The studied soil had the sandy loam texture. The 20x20-m study plot was located at the ARS Beltsville OPE3 site. Relationship between ER, bulk density, and soil water contents was first studied in disturbed 80-cm3 soil samples taken at 10 depths with 20 cm increment. Soil water contents were brought to 6 predefined levels in each sample and were in the range from air dry to 0.27g g-1. Soil bulk density varied in the range from 1.28 to 1.45 g cm-3. The ER in soil samples decreased as the gravimetric water content increased. The ER decrease became more pronounced as bulk density decreased. Next, soil samples were taken at field water contents from 10 depths at 12 locations. Particle size distributions, pH, water content and ER were measured in each sample. Bulk density values in part of the soil profiles below 80 cm ranged from 1.5 to 1.8 g cm- 3 and no dependence between ER and water content could be established in this soil layer where the lowest values of ER were recorded. The increased conductivity of the soil solid phase could be a possible reason for that since soil in this part of the profile had pH values two or more units less than in the upper part. The lowest sand contents corresponded to highest ER values in this soil layer. Finally, the vertical electrical sounding (LandMapper ERM-02) was used to infer spatial distribution of soil resistivity along a 9-m transect for different dates when soil was dry and when it was relatively uniformly wetted with long low- intensity rain. The Wenner-Shlumberger array with 31-electrodes spaced 30-cm apart was used. Soil temperature and water content with multisensor capacitance probes (SENTEC) were monitored at 10 depths down to one meter during ER measurements. High spatial variability of ER was observed. Averaging ER data along the transect resulted in a good correspondence with data from soil samples as described above. The gradual increase in ER values from the surface to the depth of about one meter probably reflected the general increase in bulk density and changes in soil texture. The small ER values found at the lowest depths with sounding were similar to those observed in samples from large depths. Depending on the range of their values, both bulk density and soil texture apparently affected or did not affect the ER. Coupling the information on soil properties in the sounded profile with the sounding data appears to be useful for interpretation of general trends in sounding results.

Guber, A. K.; Hadzick, Z. L.; Garzio, A.; Pachepsky, Y. A.; Hill, R. L.; Rowland, R. A.; Golovko, L. A.

2008-12-01

55

Determination of Electrical Resistivity of Dry Coke Beds  

Microsoft Academic Search

The electrical resistivity of the coke bed is of great importance when producing FeMn, SiMn, and FeCr in a submerged arc furnace. In these processes, a coke bed is situated below and around the electrode tip and consists of metallurgical coke, slag, gas, and metal droplets. Since the basic mechanisms determining the electrical resistivity of a coke bed is not

P. A. Eidem; M. Tangstad; J. A. Bakken

2008-01-01

56

Determination of Electrical Resistivity of Dry Coke Beds  

Microsoft Academic Search

The electrical resistivity of the coke bed is of great importance when producing FeMn, SiMn, and FeCr in a submerged arc furnace.\\u000a In these processes, a coke bed is situated below and around the electrode tip and consists of metallurgical coke, slag, gas, and metal droplets. Since the\\u000a basic mechanisms determining the electrical resistivity of a coke bed is not

P. A. Eidem; M. Tangstad; J. A. Bakken

2008-01-01

57

Experimental study on the electrical resistivity of soil cement admixtures  

NASA Astrophysics Data System (ADS)

Recently in China, soil cement is widely used to improve the soft ground in the highway construction engineering. Literature studies are mainly investigating the mechanical properties of the soil cement, while its properties of the electrical resistivity are not well addressed. In this paper, the properties of the electrical resistivity of the reconstituted soil-cement and the in situ soil cement columns are investigated. The test results show that the electrical resistivity of the soil cement increases with the increase in the cement-mixing ratio and curing time, whereas it decreases with the increase in the water content, degree of saturation and water cement ratio. A simple equation is proposed to predict the electrical resistivity of soil cement under the condition of the specified curing time and water cement ratio. It is found that the electrical resistivity has a good relationship with the unconfined compression strength and blow count of SPT. It is expected that the electrical resistivity method can be widely used for checking/controlling the quality of soil cement in practice.

Liu, Song Yu; Du, Yan Jun; Han, L. H.; Gu, M. F.

2008-05-01

58

Electrical resistance tomography using steel cased boreholes as electrodes  

DOEpatents

An electrical resistance tomography method is described which uses steel cased boreholes as electrodes. The method enables mapping the electrical resistivity distribution in the subsurface from measurements of electrical potential caused by electrical currents injected into an array of electrodes in the subsurface. By use of current injection and potential measurement electrodes to generate data about the subsurface resistivity distribution, which data is then used in an inverse calculation, a model of the electrical resistivity distribution can be obtained. The inverse model may be constrained by independent data to better define an inverse solution. The method utilizes pairs of electrically conductive (steel) borehole casings as current injection electrodes and as potential measurement electrodes. The greater the number of steel cased boreholes in an array, the greater the amount of data is obtained. The steel cased boreholes may be utilized for either current injection or potential measurement electrodes. The subsurface model produced by this method can be 2 or 3 dimensional in resistivity depending on the detail desired in the calculated resistivity distribution and the amount of data to constrain the models. 2 figs.

Daily, W.D.; Ramirez, A.L.

1999-06-22

59

Electrical Resistivity of Dilute Pdni Alloys; Local Exchange Enhancement Effects.  

National Technical Information Service (NTIS)

The contribution to the electrical resistivity of transition-metal alloys from scattering of s electrons from spin-density fluctuations in the d band is discussed. The resistivity is expressed in terms of the dynamic magnetic susceptibility of the alloy. ...

P. Lederer D. L. Mills

1968-01-01

60

Electrical Resistivity Imaging for Studying Dynamics of Vadose Zone Processes  

Microsoft Academic Search

Determining the spatial distribution of subsurface hydrologic properties is critical to developing efficient groundwater management strategies. Electrical resistivity imaging (ERI) provides continuous maps of the subsurface electrical conductivity, which can be related to water content, making it particularly useful to groundwater studies. We present an application of ERI to monitoring infiltration in the top 20 m of the subsurface at

V. Mitchell; A. Pidlisecky; R. J. Knight

2010-01-01

61

Quantifying Vegetation Driven Moisture Dynamics Using DC Electrical Resistivity  

Microsoft Academic Search

The sensitivity of electrical conductivity to soil moisture content makes time-lapse electrical resistivity imaging (ERI) an ideal method to monitor dynamic subsurface hydrological processes. While ample data show the strengths of ERI for monitoring infiltration and solute transport processes in the vadose zone, relatively few studies have evaluated the method's viability for terrestrial ecosystem research, in particular for characterizing vegetation-driven

R. L. van Dam; D. H. Jayawickreme; D. W. Hyndman

2009-01-01

62

Nonlinear electrical modeling for the resistance spot welding process  

Microsoft Academic Search

This paper deals with the nonlinear modeling of the electrical subsystem associated with the resistance spot welding (RSW) process. This will be used in the design of model-based nonlinear control strategies to achieve welds of good quality. Switched-state, thyristor driven, linear and nonlinear transformer models have been developed that characterize the electrical dynamics. A detailed parameter estimation algorithm has also

Siva Dhandapani; Michael Bridges

1999-01-01

63

The instantaneous apparent resistivity tensor: a visualization scheme for LOTEM electric field measurements  

NASA Astrophysics Data System (ADS)

Long-offset transient electromagnetic (LOTEM) data have traditionally been represented as early- and late-time apparent resistivities. Time-varying electric field data recorded in a LOTEM survey made with multiple sources can be represented by an `instantaneous apparent resistivity tensor'. Three independent, coordinate-invariant, time-varying apparent resistivities can be derived from this tensor. For dipolar sources, the invariants are also independent of source orientation. In a uniform-resistivity half-space, the invariant given by the square root of the tensor determinant remains almost constant with time, deviating from the half-space resistivity by a maximum of 6 per cent. For a layered half-space, a distance-time pseudo-section of the determinant apparent resistivity produces an image of the layering beneath the measurement profile. As time increases, the instantaneous apparent resistivity tensor approaches the direct current apparent resistivity tensor. An approximate time-to-depth conversion can be achieved by integrating the diffusion depth formula with time, using the determinant apparent resistivity at each instant to represent the resistivity of the conductive medium. Localized near-surface inhomogeneities produce shifts in the time-domain apparent resistivity sounding curves that preserve the gradient, analogous to static shifts seen in magnetotelluric soundings. Instantaneous apparent resistivity tensors calculated for 3-D resistivity models suggest that profiles of LOTEM measurements across a simple 3-D structure can be used to create an image that reproduces the main features of the subsurface resistivity. Where measurements are distributed over an area, maps of the tensor invariants can be made into a sequence of images, which provides a way of `time slicing' down through the target structure.

Caldwell, T. Grant; Bibby, Hugh M.

1998-12-01

64

Phase transformation and electrical resistivity of tetracyanoethylene under pressure  

Microsoft Academic Search

This paper reports the phase transformation behaviour of tetracyanoethylene (TCNE) under pressure as revealed by AC electrical\\u000a resistivity, its time evolution and X-ray diffraction studies. An irreversible transformation from monoclinic to cubic phase\\u000a occurs at 2.1±0.1 GPa and is indicated by a sharp resistivity drop at this pressure. The time evolution of resistivity studies\\u000a indicate that this transformation occurs via

P Ch Sahu; K Govinda Rajan; Mohammad Yousuf; R Mukhopadhyay; S L Chaplot; K R Rao

1989-01-01

65

Electrical resistivity structure in the mantle across the Mariana subduction system  

NASA Astrophysics Data System (ADS)

We have conducted a magnetotelluric (MT) survey across the central Mariana area (around 18°N) to provide a comprehensive electrical resistivity image of the mantle beneath the Mariana subduction zone, fore-arc, arc, and back-arc system, at a depths down to the transition zone. Our transect will address issues of hydration of the mantle wedge and subsequent melting, the origin of arc magmas, and melting processes beneath the slow back-arc spreading ridge axis. Electric and magnetic time series measured with seafloor instruments were cleaned and processed into MT response functions (apparent resistivity and phase), using a bounded influence algorithm with remote reference (Chave and Thomson, 2003, 2004). Topographic effects on the apparent resistivity and phase data were corrected, based on the equation of Nolasco et al. (1998), using correction tensors which were modeled with a three-dimensional forward code (Baba and Seama, 2002). The nonlinear conjugate gradient inversion algorithm, which seeks regularized solutions (Rodi and Mackie, 2001; Baba et al., 2006), was used to find an optimal two-dimensional electrical resistivity structure. This inversion algorithm allows us not only to seek a minimum structure model but also to investigate the effects of electrical anisotropy on the data. In the inversions, the TE mode apparent resistivity data (in which the electric current flow is parallel to the strike of structure) were not used because they are susceptible to resistivity anomalies by off-profile structures, and were seen to be consistently poorly fit. Sensitivity tests were applied to key features found in the obtained structure through inversions of synthetic data. The resultant isotropic electrical resistivity structure shows the following features: (1) a thick resistive Pacific plate lithosphere (roughly 100km in thickness), (2) a high resistivity region roughly in the location of the descending slab (this feature while consistent with the data is not a required feature); (3) a low resistivity region starting at a depth of about 60-70km within the mantle wedge above the slab; (4) a high resistivity region beneath the back-arc spreading ridge axis. The low resistivity feature in the mantle wedge can be attributed to melting initiated by the release of water. We have run tests on the depth to the top of this conductor in an attempt to identify the primary phases responsible for water release. The high resistivity beneath the back-arc spreading center suggests that melt delivery to the ridge crest occurs through segmented (three-dimensional) pathways, reflecting the slow spreading rate of the system. We investigated whether electrical anisotropy is required in our models, but there is no requirement for significant anisotropy either in the mantle wedge or beneath the back-arc basin.

Matsuno, T.; Seama, N.; Baba, K.; Chave, A. D.; Evans, R. L.; Goto, T.; White, A.; Boren, G.; Yoneda, A.; Utada, H.; Heinson, G. S.; Suyehiro, K.

2009-12-01

66

Design, manufacture, and analysis of metal foam electrical resistance heater  

Microsoft Academic Search

This paper presents a novel concept using the radial heating element made from porous Fe–Cr–Al metal foam in an air heater. Electrical resistance heating has been used extensively to convert the electrical energy into thermal energy. An analytic heat transfer model is first developed to estimate dimensions of the heating element. Four prototype Fe–Cr–Al metal foam electrical heaters with different

Edward J. Cookson; Donald E. Floyd; Albert J. Shih

2006-01-01

67

Electrically tailored resistance switching in silicon oxide  

NASA Astrophysics Data System (ADS)

Resistive switching in a metal-free silicon-based material offers a compelling alternative to existing metal oxide-based resistive RAM (ReRAM) devices, both in terms of ease of fabrication and of enhanced device performance. We report a study of resistive switching in devices consisting of non-stoichiometric silicon-rich silicon dioxide thin films. Our devices exhibit multi-level switching and analogue modulation of resistance as well as standard two-level switching. We demonstrate different operational modes that make it possible to dynamically adjust device properties, in particular two highly desirable properties: nonlinearity and self-rectification. This can potentially enable high levels of device integration in passive crossbar arrays without causing the problem of leakage currents in common line semi-selected devices. Aspects of conduction and switching mechanisms are discussed, and scanning tunnelling microscopy (STM) measurements provide a more detailed insight into both the location and the dimensions of the conductive filaments.

Mehonic, Adnan; Cueff, Sébastien; Wojdak, Maciej; Hudziak, Stephen; Labbé, Christophe; Rizk, Richard; Kenyon, Anthony J.

2012-11-01

68

COMPLEX ELECTRICAL RESISTIVITY FOR MONITORING DNAPL CONTAMINATION  

EPA Science Inventory

We propose to develop new practical complex resistivity field measurement techniques for pollution characterization and monitoring. For this purpose we will document the detectability of clay-organic interactions with geophysical measurements in the laboratory, develop further un...

69

Profile of ambulatory blood pressure in resistant hypertension.  

PubMed

Resistant hypertension (HT) is a condition that confers a high cardiovascular risk to the patient due to both persistent blood pressure elevation and the high prevalence of comorbidities and organ damage. Ambulatory blood pressure monitoring (ABPM) has become an important tool in the diagnosis and follow-up of the hypertensive patient, and it is even more important in the evaluation of those with resistant HT. Data from the Spanish ABPM Registry have allowed the comparison between large groups of resistant hypertensive patients seen in daily life and those controlled on antihypertensive treatment, as well as in resistant hypertensive patients who are classified based on ambulatory blood pressure values. In comparison with controlled patients, the cohort of resistant hypertensives has a worse circadian profile with a high proportion of nondipping, but also stark differences between office and ambulatory blood pressures. This enhanced white-coat effect was responsible for more than one-third of resistant hypertensive patients having normal 24-h blood pressures. Clinical data, including comorbidities, organ damage and circadian patterns, suggest a lower cardiovascular risk among white-coat resistant hypertensives. This finding was in agreement with longitudinal studies in smaller cohorts, suggesting fewer cardiovascular events and less mortality. In summary, it seems reasonable to routinely use ABPM in the initial evaluation of all resistant hypertensive patients. In a significant number of these patients, ABPM will also be an essential tool in follow-up, especially regarding the possible effects of all therapeutic maneuvers that are devoted to bringing blood pressure into target ranges. PMID:23595047

de la Sierra, Alejandro

2013-04-18

70

Monitoring of Leachate Recirculation in a Bioreactor Using Electrical Resistivity  

NASA Astrophysics Data System (ADS)

The bioreactor is a concept of waste landfill management consisting in speeding up the biodegradation by optimizing the moisture content through leachate recirculation. Electrical resistivity tomography (ERT) is carried out with fast resistivity-meter (Syscal Pro, IRIS Instruments, developed in the framework of the research project CERBERE 01V0665-69, funded by the French Research Ministry) to monitor leachate recirculation. During a recirculation period waste moisture increases, so that electrical resistivity may decrease, but at the same time temperature and mineralization of both waste and leachate become intermixed. If waste temperature is much higher than leachate temperature electrical resistivity will not decrease as much as if the temperature difference was smaller. If leachate mineralization (i.e. leachate conductivity) is higher than that of wet waste in the landfill, electrical resistivity will tend to decrease. Otherwise for example after an addition of rain water into the leachate storage or in case of very wet waste, the resistivities of each medium (leachate and wet waste) can be almost the same, so that leachate mineralization will not have a great influence on waste resistivity. Resistivity measurements were performed during 85 minutes injection trials (with a discharge of 20 m3 h-1) where leachate was injected through a vertical borehole perforated between 1.85 and 4.15 m. Three first measurements are made during the injection (3, 30 and 60 minutes from the beginning of the injection) and the two other after the injection period (8 and 72 minutes after the end of the injection). Apparent and interpreted resistivity variations that occurred during injection trials, expressed as the relative differences (in %) between apparent, respectively interpreted, resistivity during injection and apparent, respectively interpreted, resistivity before injection (reference measurement) show the formation of a plume (a negative anomaly: resistivity decreases with increasing moisture content). The positive anomaly could be explained by an increasing of biogas proportion in waste porosity. For this experiment, leachate temperature is relatively cold (between 5 and 10° C, as the injection trials take place at the end of October), leachate conductivity is about 9200 ? S cm-1 (i.e. a resistivity of 1.1 ? m) and waste resistivity in the borehole region is about 80 ? m. This is a situation where the temperature difference between waste and leachate is large and the resistivity difference between waste and leachate is high. The resistivity variation is essentially due to waste moisture increase. ERT method allows leachate diffusion to be seen through the waste mass and the influence zone of the leachate recirculation system to be determined.

Grellier, S.; Bureau, N.; Robain, H.; Tabbagh, A.; Camerlynck, C.; Guerin, R.

2004-05-01

71

Electrical Resistivity Measurements of Hot Dense Aluminum  

NASA Astrophysics Data System (ADS)

Electrical transport properties of dense aluminum are measured in the disordered liquidlike phase using a well-tamped, thermally equilibrated, exploding wire z pinch. Direct measurements of the electrical conductivity have been made using voltage and current measurements. Our measurements span the minimum conductivity regime, at higher densities than have been produced previously. We find that some Ziman-like theoretical predictions are in fair agreement with the data and one Ziman-like theoretical approach is in good agreement, in contrast to other experiments performed in similar regimes which indicate poor agreement with such theories.

Benage, J. F.; Shanahan, W. R.; Murillo, M. S.

1999-10-01

72

Thermal shock resistance of electrical insulators  

Microsoft Academic Search

The thermal shock resistance factors R and R' of a solid can be defined in terms of its thermal conductivity k, thermal expansion coefficient of ?, elastic modulus E and tensile strength St. The thermal conductivity and expansion coefficient of an insulating crystalline material can be eliminated in favour of the mean atomic weight A, the melting temperature Tm and

H J Goldsmid

1963-01-01

73

Electrically tailored resistance switching in silicon oxide.  

PubMed

Resistive switching in a metal-free silicon-based material offers a compelling alternative to existing metal oxide-based resistive RAM (ReRAM) devices, both in terms of ease of fabrication and of enhanced device performance. We report a study of resistive switching in devices consisting of non-stoichiometric silicon-rich silicon dioxide thin films. Our devices exhibit multi-level switching and analogue modulation of resistance as well as standard two-level switching. We demonstrate different operational modes that make it possible to dynamically adjust device properties, in particular two highly desirable properties: nonlinearity and self-rectification. This can potentially enable high levels of device integration in passive crossbar arrays without causing the problem of leakage currents in common line semi-selected devices. Aspects of conduction and switching mechanisms are discussed, and scanning tunnelling microscopy (STM) measurements provide a more detailed insight into both the location and the dimensions of the conductive filaments. PMID:23064085

Mehonic, Adnan; Cueff, Sébastien; Wojdak, Maciej; Hudziak, Stephen; Labbé, Christophe; Rizk, Richard; Kenyon, Anthony J

2012-10-12

74

Electrical resistivity of iron at high pressure and high temperature  

NASA Astrophysics Data System (ADS)

Knowledge of thermal conductivity of iron under high-pressure and temperature conditions is crucial to understand the heat transport and the thermal evolution of planetary interior. However, measurements of thermal conductivity at high pressure and temperature are challenging and experimental data are limited. In this study, we report the measured electrical resistivity of iron at high pressure and temperature. The data are then translated to thermal conductivity through Wiedemann-Franz law. A four-probe method was employed to measure the resistances of a cylindrical wire during heating cycles at high pressure. Experiments at 5, 7 and 13 GPa were performed on an iron wire sample by using a multi-anvil apparatus at the Geophysical Laboratory. At 5, 7 and 13 GPa, the measured electrical resistivity of iron at room temperature are 9.06 m?-cm (bcc phase), 8.85 m?-cm (bcc phase) and 12.72 m?-cm (hcp phase), respectively. The results are in a good agreement with reported room-temperature data. The kinks in electrical resistivity associated with the phase transitions of iron were clearly observed in each run. At 5 and 7 GPa, kinks in the electrical resistivity can be noticed at 677 oC and 652 oC, respectively, due to the bcc to fcc phase transition. At 5 GPa and 1687 oC, melting led to a discontinuous change in electrical resistivity. The temperature dependence of the electrical resistivity for bcc, fcc, and hcp iron are well constrained from these measurements. The hcp iron displays the strongest temperature dependence compared with that of the bcc and fcc phases. Our results provide critical thermodynamic parameters to constrain heat transport in the planetary cores.

Deng, L.; Seagle, C.; Fei, Y.; Shahar, A.

2011-12-01

75

Cross-resistance profile of mesosulfuron-methyl-resistant Italian ryegrass in the southern United States.  

PubMed

Diclofop-resistant Lolium species (ryegrass) is a major weed problem in wheat production worldwide. This study was conducted to determine the resistance pattern of diclofop-resistant ryegrass accessions from the southern United States to mesosulfuron-methyl, a recently commercialized herbicide for ryegrass control in wheat; to determine the cross-resistance pattern of a Lolium multiflorum Lam. (Italian ryegrass) accession, 03-1, to acetolactate synthase (ALS) and acetyl-CoA carboxylase (ACCase) inhibitors; and to determine the resistance mechanism of Italian ryegrass to mesosulfuron-methyl. Seventeen ryegrass accessions from Arkansas and Louisiana, including standard resistant and susceptible accessions, were used in this experiment. Fourteen of the 17 accessions were more resistant (four- to > 308-fold) to diclofop than the standard susceptible biotype. One accession, 03-1, was resistant to mesosulfuron-methyl as well as to other ALS inhibitor herbicides such as chlorsulfuron, imazamox and sulfometuron. Accession 03-1, however, did not show multiple resistance to the ACCase inhibitor herbicides diclofop, fluazifop, clethodim, sethoxydim and pinoxaden, nor to glyphosate. The in vivo ALS activity of the 03-1 biotype was less affected by mesosulfuron-methyl than the susceptible biotype. This indicates that the resistance mechanism of Italian ryegrass to mesosulfuron-methyl is partly due to an alteration in the target enzyme, ALS. It is concluded that diclofop-resistant ryegrass in the southern United States can be generally controlled by mesosulfuron-methyl. However, mesosulfuron-methyl must be used with caution because not all ryegrass populations are susceptible to it. There is a need for more thorough profiling of ryegrass resistance to herbicides. PMID:17315272

Kuk, Yong In; Bugos, Nilda R

2007-04-01

76

The borehole-fluid effect in electrical resistivity imaging  

NASA Astrophysics Data System (ADS)

Fluid that fills boreholes in crosswell electrical-resistivity investigations provides the necessary electrical contact between the electrodes and the rock formation, but it is also the source of image artifacts in standard inversions that do not account for the effects of the boreholes. The image distortions can be severe for large resistivity contrasts between the rock formation and borehole fluid and for large borehole diameters. We have carried out 3-D finite-element modeling using an unstructured-grid approach to quantify the magnitude of borehole effects for different resistivity contrasts, borehole diameters, and electrode configurations. Relatively common resistivity contrasts of 100 : 1 and borehole diameters of 10 and 20 cm yielded, for a bipole length 5 m, underestimates of apparent resistivity by ~12% and ~32% when using AB-MN configurations and overestimates of apparent resistivity by ~24% and ~95% when using AM-BN configurations. Effects are generally more severe at shorter bipole spacings. We report here the results obtained by either including or ignoring the boreholes in inversions of 3D field data from a test site in Switzerland, where ~10,000 crosswell resistivity tomography measurements were made across 6 acquisition planes between 4 boreholes. Inversions of raw data that ignored the boreholes filled with low resistivity fluid paradoxically produced high resistivity artifacts around the boreholes. Including correction factors based on the modeling results for a 1-D model with and without the boreholes did not markedly improve the images. The only satisfactory approach was to use a 3-D inversion code that explicitly incorporated the boreholes in the actual inversion. This new approach yielded an electrical resistivity image that was devoid of artifacts around the boreholes and that correlated well with co-incident crosswell radar images.

Doetsch, Joseph; Coscia, Ilaria; Greenhalgh, Stewart; Linde, Niklas; Green, Alan G.; Günther, Thomas

2010-05-01

77

Electrical resistivity investigations at the Olkaria geothermal field, Kenya  

SciTech Connect

The bipole-dipole, Schlumberger and in line dipole-dipole electrical resistivity configurations were used to delineate the Olkaria geothermal reservoir with the view to site boreholes for the production of electric power using the geopressurized hot water. The dipole-dipole resistivity data provided the least ambiguous and most usable data for assessing the resource. Deep drilling into two of the anomalies outlined by this survey has proved the existence of high-temperature reservoirs and a 15MW power station is under construction.

Bhogal, P.S.

1980-09-01

78

Electrical resistivity of Au-ZnO nanocomposite films  

NASA Astrophysics Data System (ADS)

The electrical resistivity of electron beam codeposited gold and zinc oxide (Au-ZnO) films was investigated over the full composition range. The electrical resistivity was shown to increase monotonically with increasing ZnO content, with three characteristic regimes of behavior associated primarily with (1) grain boundary electron scattering due to grain refinement at ZnO volume fractions below 0.3, (2) percolation theory for ZnO volume fractions at and above the percolation threshold (fc = 0.85), and (3) a transition region between these where it was proposed that resistivity was influenced by the formation of Au-Zn complexes due to an oxygen deficiency in the deposited ZnO. The electrical resistivity of the composite films remained below 100 ?? cm for ZnO volume fractions below 0.5. A model combining the general effective media equation and Mayadas-Shatzkes grain boundary electron scattering model was shown to generally describe the composition dependence of electrical resistivity for the investigated oxide dispersion hardened metal-matrix composite thin films.

Argibay, N.; Goeke, R. S.; Dugger, M. T.; Rodriguez, M. A.; Michael, J. R.; Prasad, S. V.

2013-04-01

79

Skin electrical resistance does not change following infraclavicular block.  

PubMed

Peripheral nerve blocks are common and effective means for anesthesia for limb surgery. The evaluation of the success of a peripheral blockade is based on the loss of sensation, with no objective means of detecting a successful block. The autonomic innervation to the upper extremity, which controls both the vascular tone and the activity of sweat glands, is supplied by nerve fibers accompanying the somatic nerve fibers. Previous studies have shown changes in both skin temperature and electrical resistance of the skin following brachial plexus block. We studied 20 patients undergoing hand surgery under infraclavicular brachial plexus block. The electrical resistance of the skin on the palmar aspect of the forearm was continuously recorded on the block arm and on the contralateral arm using a commercial skin resistance monitor. No statistically significant change in the electrical resistance of the skin was observed during 20 minutes after placement of the block. These results strongly suggest that the electrical resistance of the skin cannot be used to predict a successful infraclavicular block. PMID:22848979

Lehavi, Amit; Kiorescu, Alexander; Abecasis, Philippe; Baskevitch, Arkady; Katz, Yeshayahu

2012-06-01

80

Using electrical resistance tomography to map subsurface temperatures  

SciTech Connect

A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass/rock mass. Tomographs of electrical resistivity are calculated based on the measurements using Poisson's equation. Changes in the soil/rock resistivity can be related to changes in soil/rock temperatures when: (1) the electrical conductivity of the fluid trapped in the soil's pore space is low, (2) the soil/rock has a high cation exchange capacity and (3) the temperature changes are sufficiently high. When these three conditions exist the resistivity changes observed in the ERT tomographs can be directly attributed to changes in soil/rock temperatures. This method provides a way of mapping temperature changes in subsurface soils remotely. Distances over which the ERT method can be used to monitor changes in soil temperature range from tens to hundreds of meters from the electrode locations.

Ramirez, Abelardo L. (Pleasanton, CA); Chesnut, Dwayne A. (San Francisco, CA); Daily, William D. (Livermore, CA)

1994-01-01

81

Structure and electrical properties of heat-resistant bimetallic conductors  

Microsoft Academic Search

From 1964 to the present, many works have been devoted to studying bimetallic wire with a heat-resistant jacket of nickel\\u000a or corrosion-resistant steel and a core of a metal with a high electrical conductivity such as copper or silver. This wire\\u000a retains its operating capacity up to 700C and is widely used as a high-temperature conductor in various fields of

V. I. Bokshitskii; A. M. Glezer; E. K. Zakharov; G. A. Sveshnikova

1997-01-01

82

Monitoring of Leachate Recirculation in a Bioreactor Using Electrical Resistivity  

Microsoft Academic Search

The bioreactor is a concept of waste landfill management consisting in speeding up the biodegradation by optimizing the moisture content through leachate recirculation. Electrical resistivity tomography (ERT) is carried out with fast resistivity-meter (Syscal Pro, IRIS Instruments, developed in the framework of the research project CERBERE 01V0665-69, funded by the French Research Ministry) to monitor leachate recirculation. During a recirculation

S. Grellier; N. Bureau; H. Robain; A. Tabbagh; C. Camerlynck; R. Guerin

2004-01-01

83

Resistance after firing protected electric match. [Patent application  

DOEpatents

An electric match having electrical leads embedded in flame-producing compound is protected against an accidental resistance across the leads after firing by a length of heat-shrinkable tubing encircling the match body and having a skirt portion extending beyond the leads. The heat of the burning match and an adjacent thermal battery causes the tubing to fold over the end of the match body, covering the ends of the leads and protecting them from molten pieces of the battery.

Montoya, A.P.

1980-03-20

84

Consolidation by electrical resistance sintering of Ti powder  

Microsoft Academic Search

In this study, commercially pure Ti powder was consolidated by the electrical resistance sintering (ERS) technique. This consolidation\\u000a technique consists of the application of pressure (around 100 MPa) to a powder mass at the same time that the powder is heated\\u000a by the passage of an electric current of high intensity (around 10 kA), low voltage (around 5 V) and a frequency of

J. M. MontesJ; J. A. Rodríguez; F. G. Cuevas; J. Cintas

2011-01-01

85

LANDMAPPER™ ERM01. ELECTRICAL RESISTIVITY MAPPING DEVICE FOR PRECISION HORTICULTURE  

Microsoft Academic Search

On-the- go sensors, designed to measure soil electrical resistivity (ER) or electrical conductivity (EC) are vital for faster non-destructive soil mapping in Precision Agriculture applications. Commercially available contact devices, which utilize a four-electrode principle, are bulky, very expensive, and can be used only on fallow fields. This limits their applications on small and mid-sized farms, which produce perennial horticultural crops,

L. Pozdnyakova; P. V. Oudemans; A. I. Pozdnyakov; M. S. Kelly

86

Nondestructive evaluation of composite materials by electrical resistance measurement  

NASA Astrophysics Data System (ADS)

This dissertation investigates electrical resistance measurement for nondestructive evaluation of carbon fiber (CF) reinforced polymer matrix composites. The method involves measuring the DC electrical resistance in either the longitudinal or through thickness direction. The thermal history and thermal properties of thermoplastic/CF composites were studied by longitudinal and through-thickness resistance measurements. The resistance results were consistent with differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) results. The resistance measurements gave more information on the melting of the polymer matrix than TMA. They were more sensitive to the glass transition of the polymer matrix than DSC. The through-thickness resistance decreased as autohesion progressed. The activation energy of autohesion was 21.2 kJ/mol for both nylon-6 and polyphenylene sulfide (PPS)/CF composites. Adhesive bonding and debonding were monitored in real-time by measurement of the through-thickness resistance between the adherends in an adhesive joint during heating and subsequent cooling. Debonding occurred during cooling when the pressure or temperature during prior bonding was not sufficiently high. A long heating time below the melting temperature (T m) was found to be detrimental to subsequent PPS adhesive joint development above Tm, due to curing reactions below Tm and consequent reduced mass flow response above Tm. A high heating rate (small heating time) enhanced the bonding more than a high pressure. The longitudinal resistance measurement was used to investigate the effects of temperature and stress on the interface between a concrete substrate and its epoxy/CF composite retrofit. The resistance of the retrofit was increased by bond degradation, whether the degradation was due to heat or stress. The degradation was reversible. Irreversible disturbance in the fiber arrangement occurred slightly as thermal or load cycling occurred, as indicated by the resistance decreasing cycle by cycle. This dissertation also addresses the use of the electrical resistance method to observe thermal and mechanical damage in real time. A temperature increase caused the interlaminar contact resistance to decrease reversibly within each thermal cycle, while thermal damage caused the resistance to decrease abruptly and irreversibly, due to matrix molecular movement and the consequent increase in the chance of fibers of one lamina touching those of an adjacent lamina. The through-thickness volume resistivity irreversibly and gradually decreased upon mechanical damage, which was probably fiber-matrix debonding. Moreover, it reversibly and abruptly increased upon matrix micro-structural change, which occurred reversibly near the peak stress of a stress cycle.

Mei, Zhen

87

Electrical conductivity of the Fennoscandian Shield margin from recent magnetotelluric profiles  

NASA Astrophysics Data System (ADS)

During the last decade several magnetotelluric profiles extending from Proterozoic East European Craton into younger domains have been measured. Magnetotelluric TOR profile crosses the Sorgenfrei-Tornquist-Zone (STZ) in the southwestern part of the Fennoscandian Shield. The STZ marks the border between the intact shield in Sweden to the north and the reactivated Danish basin and the Ringkobing-Fyn High (RFH) to the south. The STZ manifests itself electrically very clearly in the lower crust and upper lithospheric mantle as a narrow zone of high conductivity. The thickness of the electric lithosphere decreases across the STZ from about 300 km in the Fennoscandian Shield to about 100 km in the Danish basin. Jämtland-Trondelag magnetotelluric profile crosses the Central Scandinavian Caledonides from Baltic to Norwegian Sea. The results of the data analysis reveal the following main features: (1) An electrically highly conducting layer beneath the Caledonides images alum shales, the autochthonous Cambrian carbon-bearing black shales on top of the Precambrian basement. (2) Beneath the eastern part of the profile in the Fennoscandian Shield, proper, the first upper mantle conductor is detected at the depth of more than 250-300 km. A region of enhanced conductivity is identified at the depth of c.100- 150 km under the Caledonides in the central part of the profile. Further to the west, however, the lithosphere seems to thicken to 150-200 km. A large-scale international electromagnetic experiment has been carried out in northwest Poland and northeast Germany across the Trans European Suture Zone (TESZ), which is the most prominent tectonic boundary in Europe and which constitutes a complex transition between the European Paleozoic Platform towards the southeast and the Precambrian Craton towards the northeast. The results show the presence of highly conductive Cenozoic-Mesozoic sedimentary cover reaching depths up to 3 km. The significant conductivity anomaly in the central part of the TESZ in the Polish Trough at mid-crustal depths is well resolved. The upper mantle of the Precambrian Craton is more resistive than the younger Paleozoic lithosphere by at least one order of magnitude. We can summarize the results from these profiles in the following conclusions. Magnetotelluric data revealed remarkable features at the crustal level along each profile. Some of them were not clearly identified before by other geophysical methods. Conductors like alum shales are very well indicated in the final models. Electrical lithosphere is thick beneath the Fennoscandian Shield and significantly thinner beneath younger domains. The resulting models shows the conductivity contrast at a depth of about 150 km across the cratonic margin to be at least one order of magnitude.

Smirnov, M. Yu.; Korja, T.; Pedersen, L. B.

2009-04-01

88

An alternative methodology for the analysis of electrical resistivity data from a soil gas study  

NASA Astrophysics Data System (ADS)

The aim of this paper is to present an alternative method for the analysis of resistivity data. The methodology was developed during a study to evaluate if electrical resistivity can be used as a tool for analysing subsurface gas dynamics and gas emissions from landfills. The main assumption of this study was that variations in time of resistivity data correspond to variations in the relative amount of gas and water in the soil pores. Field measurements of electrical resistivity, static chamber gas flux and weather data were collected at a landfill in Helsingborg, Sweden. The resistivity survey arrangement consisted of nine lines each with 21 electrodes in an investigation area of 16 ×20 m. The ABEM Lund Imaging System provided vertical and horizontal resistivity profiles every second hour. The data were inverted in Res3Dinv using L1-norm-based optimization method with a standard least-squares formulation. Each horizontal soil layer was then represented as a linear interpolated raster model. Different areas underneath the gas flux measurement points were defined in the resistivity model of the uppermost soil layer, and the vertical extension of the zones could be followed at greater depths in deeper layer models. The average resistivity values of the defined areas were calculated and plotted on a time axis, to provide graphs of the variation in resistivity with time in a specific section of the ground. Residual variation of resistivity was calculated by subtracting the resistivity variations caused by the diurnal temperature variations from the measured resistivity data. The resulting residual resistivity graphs were compared with field data of soil moisture, precipitation, soil temperature and methane flux. The results of the study were qualitative, but promising indications of relationships between electrical resistivity and variations in the relative amount of gas and water in the soil pores were found. Even though more research and better data quality is necessary for verification of the results presented here, we conclude that this alternative methodology of working with resistivity data seems to be a valuable and flexible tool for this application.

Johansson, Sara; Rosqvist, Hâkan; Svensson, Mats; Dahlin, Torleif; Leroux, Virginie

2011-08-01

89

Using electrical resistance probes for moisture determination in switchgrass windrows  

Technology Transfer Automated Retrieval System (TEKTRAN)

Determining moisture levels in windrowed biomass is important for both forage producers and researchers. Energy crops such as switchgrass have been troublesome when using the standard methods set for electrical resistance meters. The objectives of this study were to i) develop the methodologies need...

90

Health Monitoring of TPS Structures by Measuring Their Electrical Resistance  

NASA Astrophysics Data System (ADS)

Health Monitoring in aerospace applications becomes an emerging technology leading to the development of systems capable of continuously monitoring structures for damage with minimal human intervention. A promising sensing method to be applied on hot structures and thermal protection systems is the electrical resistance measurement technique, which is barely investigated up to now. This method benefits from the advantageous characteristics of self-monitoring materials, such as carbon fiber-reinforced materials. By measuring the variation of the electrical resistance of these materials information on possibly present mechanical damage can be derived. In order to set up a database on electric properties of relevant materials under relevant conditions and to perform a proof-of-concept for this health monitoring method a facility has been laid out, which allows for the measurement of the electrical resistance of thermal protection system relevant materials at temperatures up to 2000°C. First preliminary measurements of the surface resistance of a graphite sample have been performed and are presented. It has been proven necessary to make some modifications to the setup. Therefore, the remaining measurements with graphite and C/C-SiC samples are subject of further investigation which will be performed in the future.

Preci, Arianit; Herdrich, Georg; Steinbeck, Andreas; Auweter-Kurtz, Monika

91

Low Temperature Electrical Resistivity Measurements on Reactive Samples  

Microsoft Academic Search

An apparatus and a technique for measuring electrical resistivities on reactive samples are described. Measurements were made in an inert atmosphere vacuum glove box containing a high purity helium environment. A precision micromanipulator was used to position a four point probe while observation was made through a microscope to guide the positioning of the probe. A cold stage permitted measurements

J. G. Pack; G. G. Libowitz

1969-01-01

92

Electrical Resistance Wire Strain-Gauges to Measure Large Strains  

Microsoft Academic Search

I WISH to direct attention to the performance of `Minalpha' wire as supplied by Johnson Matthey when used as the filament in an electrical resistance wire strain-gauge, and also to indicate the effect of the connexion between the filament wire and the stout wire used to connect it to the measuring bridge.

K. H. Swainger

1947-01-01

93

Using an Automatic Resistivity Profiler Soil Sensor On-The-Go in Precision Viticulture  

PubMed Central

Spatial information on vineyard soil properties can be useful in precision viticulture. In this paper a combination of high resolution soil spatial information of soil electrical resistivity (ER) and ancillary topographic attributes, such as elevation and slope, were integrated to assess the spatial variability patterns of vegetative growth and yield of a commercial vineyard (Vitis vinifera L. cv. Tempranillo) located in the wine-producing region of La Rioja, Spain. High resolution continuous geoelectrical mapping was accomplished by an Automatic Resistivity Profiler (ARP) on-the-go sensor with an on-board GPS system; rolling electrodes enabled ER to be measured for a depth of investigation approximately up to 0.5, 1 and 2 m. Regression analysis and cluster analysis algorithm were used to jointly process soil resistivity data, landscape attributes and grapevine variables. ER showed a structured variability that matched well with trunk circumference spatial pattern and yield. Based on resistivity and a simple terrain attribute uniform management units were delineated. Once a spatial relationship to target variables is found, the integration of point measurement with continuous soil resistivity mapping is a useful technique to identify within-plots areas of vineyard with similar status.

Rossi, Roberta; Pollice, Alessio; Diago, Maria-Paz; Oliveira, Manuel; Millan, Borja; Bitella, Giovanni; Amato, Mariana; Tardaguila, Javier

2013-01-01

94

Rolling resistance of electric-vehicle tires from track tests  

SciTech Connect

Two sets of low-rolling-resistance tires were track tested to obtain realistic tire characteristics for use in programming the Road Load Simulator, a special dynamometer facility located at the NASA Lewis Research Center. One set was specially made by Goodyear Tire and Rubber Company for DOE's ETV-1 electric vehicle, and the other was a set of standard commercial automotive tires. The tests were conducted over an ambient temperature range of 15/sup 0/ to 32/sup 0/C (59/sup 0/ to 89/sup 0/F) and with tire pressures of 207 and 276 kPa (30 and 40 psi). Both sets of tires had very low rolling resistance. The commercial tires, which were manufactured approximately 3 years after the electric vehicle tires, exhibited lower rolling resistance than the electric vehicle tires. This is a result of the continuing effort by the tire manufacturers to reduce rolling resistance in order to improve fuel economy. At a contained-air temperature of 38/sup 0/C (100/sup 0/F) and a pressure of 207 kPa (30 psi), the resistance of the electric vehicle tires was 0.0102 kilogram per kilogram of vehicle weight and the resistance of the commercial tires was 0.0088 kilogram per kilogram of vehicle weight. At a contained-air temperature of 38/sup 0/C (100/sup 0/F) and a pressure of 276 kPa (40 psi), the resistance of the electric vehicle tires was 0.009 kilogram per kilogram of vehicle weight and the resistance of the commercial tires was 0.0074 kilogram per kilogram of vehicle weight. The average time for the tires to reach an equilibrium temperature after startup was 20 minutes for the constant-speed tests regardless of vehicle speed and 27 minutes for the SAE J227a Schedule D driving cycle tests. The average change in rolling resistance from startup to final equilibrium value was 5% for all tests. There was very little heating of the tires from velocity-dependent losses. The predominant heating source for these tires was radiation heating from the Sun.

Dustin, M.O.; Slavik, R.J.

1982-06-01

95

Continuous resistivity profiling survey in Mersin Harbour, Northeastern Mediterranean Sea  

NASA Astrophysics Data System (ADS)

No detailed information has previously been available on the geological and geophysical characteristics of the sea floor and the underlying strata of Mersin Harbour, Northeastern Mediterranean Sea (Turkey). Continuous resistivity profiling (CRP) and borehole data from Mersin Harbour were used to interpret geoelectric stratigraphy of Neogene-Quaternary sediments in the area. This represents one of few such detailed case studies that have applied these valuable CRP techniques for the purpose of marine stratigraphic imaging. It was found that the Neogene-Quaternary sedimentary succession in the area consists of three geoelectric units (GU1, GU2, and GU3 from base to top). The lowest unit, GU1, has a resistivity value of greater than 20.0 ohm-m and consists of Miocene aged limestone and marl. The middle unit, GU2, is characterized by resistivity values ranging from 3.0 to 20.0 ohm-m. Its thickness is greater than 90 m, with the upper section being composed of stiff clay sequences which are Plio-Pleistocene in age. The uppermost unit, GU3, has resistivity values varying from 1.0 to 3.0 ohm-m. This unit displays a maximum thickness of 15 m, and is composed of Holocene muds together with gravel, sand, silt and clay (sometimes incorporating shells) materials of the Plio-Pleistocene age and their various mixtures, silty/clay limestone, and conglomerate sandstone. Comparisons of the geoelectric units with the depositional sequences interpreted from the available seismic data outwith, but close to, Mersin Harbour reveal that the geoelectric unit GU3 corresponds to the depositional sequences C (mainly Holocene) and B (mainly Plio-Pleistocene). The geoelectric unit GU2 partly correlates with the depositional sequence B which appears to be Plio-Pleistocene in age. The geoelectric unit GU1, which has not been encountered in previous seismic surveys, is a new discovery within Mersin Harbour. Limited correlation between the seismic and resistivity structures in the study area is attributed to differences in the acoustic impedance and resistivity contrasts of sub-bottom layers, as well as the penetration versus resolution performance of the systems.

Okyar, Mahmut; Y?lmaz, Sedat; Tezcan, Devrim; Çava?, Hakan

2013-06-01

96

Small-Scale Electrical Resistivity Tomography of Wet Fractured Rocks  

SciTech Connect

This paper describes a series of experiments that tested the ability of the electrical resistivity tomography (ERT) method to locate correctly wet and dry fractures in a meso-scale model. The goal was to develop a method of monitoring the flow of water through a fractured rock matrix. The model was a four by six array of limestone blocks equipped with 28 stainless steel electrodes. Dry fractures were created by placing pieces of vinyl between one or more blocks. Wet fractures were created by injecting tap water into a joint between blocks. In electrical terms, the dry fractures are resistive and the wet fractures are conductive. The quantities measured by the ERT system are current and voltage around the outside edge of the model. The raw ERT data were translated to resistivity values inside the model using a three-dimensional Occam's inversion routine. This routine was one of the key components of ERT being tested. The model presented several challenges. First, the resistivity of both the blocks and the joints was highly variable. Second, the resistive targets introduced extreme changes the software could not precisely quantify. Third, the abrupt changes inherent in a fracture system were contrary to the smoothly varying changes expected by the Occam's inversion routine. Fourth, the response of the conductive fractures was small compared to the background variability. In general, ERT was able to locate correctly resistive fractures. Problems occurred, however, when the resistive fracture was near the edges of the model or when multiple fractures were close together. In particular, ERT tended to position the fracture closer to the model center than its true location. Conductive fractures yielded much smaller responses than the resistive case. A difference-inversion method was able to correctly locate these targets.

Wood, Thomas Ronald; Heath, Gail Lynn; LaBrecque, Douglas J.; Sharpe, Roger

2004-01-01

97

Small-scale electrical resistivity tomography of wet fractured rocks.  

PubMed

This paper describes a series of experiments that tested the ability of the electrical resistivity tomography (ERT) method to locate correctly wet and dry fractures in a meso-scale model. The goal was to develop a method of monitoring the flow of water through a fractured rock matrix. The model was a four by six array of limestone blocks equipped with 28 stainless steel electrodes. Dry fractures were created by placing pieces of vinyl between one or more blocks. Wet fractures were created by injecting tap water into a joint between blocks. In electrical terms, the dry fractures are resistive and the wet fractures are conductive. The quantities measured by the ERT system are current and voltage around the outside edge of the model. The raw ERT data were translated to resistivity values inside the model using a three-dimensional Occam's inversion routine. This routine was one of the key components of ERT being tested. The model presented several challenges. First, the resistivity of both the blocks and the joints was highly variable. Second, the resistive targets introduced extreme changes the software could not precisely quantify. Third, the abrupt changes inherent in a fracture system were contrary to the smoothly varying changes expected by the Occam's inversion routine. Fourth, the response of the conductive fractures was small compared to the background variability. In general, ERT was able to locate correctly resistive fractures. Problems occurred, however, when the resistive fracture was near the edges of the model or when multiple fractures were close together. In particular, ERT tended to position the fracture closer to the model center than its true location. Conductive fractures yielded much smaller responses than the resistive case. A difference-inversion method was able to correctly locate these targets. PMID:14763623

LaBrecque, Douglas J; Sharpe, Roger; Wood, Thomas; Heath, Gail

98

Electrical resistivity imaging of conductive plume dilution in fractured rock  

NASA Astrophysics Data System (ADS)

Electrical resistance tomography (ERT) was used to monitor a conductive plume dilution experiment that was conducted in fractured basalt in order to assess its applications in this type of fractured-rock environment. Tap water was injected into an injection well for 34 days to dilute a pre-existing potassium chloride (KCl) plume at a site in Idaho, USA. No further fluids were introduced artificially during a 62-day monitoring period. Both surface ERT and cross-borehole ERT were used to monitor dilution and displacement of the plume. A square grid of land-surface electrodes was used with the surface ERT. Three-dimensional images of surface ERT delineated areas of increased and decreased resistivities. Increasing resistivities are attributed to dilution/displacement of the KCl solution by tap-water invasion or the influx of seasonal recharge. Decreasing resistivities resulted from redistribution of residual KCl solution. Cross-borehole ERT was conducted between the injection well and each of seven surrounding monitoring wells. Polar plots of the injection-well resistivity data in the direction of each monitoring well delineate specific locations where tap water seeped from the injection well via preferential flow paths determined by time-dependent resistivity increases. Monitoring-well data indicate locations of clustered and isolated regions of resistivity changes.

Nimmer, Robin E.; Osiensky, James L.; Binley, Andrew M.; Sprenke, Kenneth F.; Williams, Barbara C.

2007-08-01

99

Monitoring an underground steam injection process using electrical resistance tomography  

NASA Astrophysics Data System (ADS)

We used electrical resistance tomography (ERT) to map the subsurface distribution of a steam flood as a function of time as part of a prototype environmental restoration process performed by the Dynamic Underground Stripping Project. We evaluated the capability of ERT to monitor changes in the soil resistivity during the steam injection process using a dipole-dipole measurement technique to measure the bulk electrical resistivity distribution in the soil mass. The injected steam caused changes in the soil's resistivity because the steam displaced some of the native pore water, increased the pore water and soil temperatures and changed the ionic content of the pore water. We could detect the effects of steam invasion by mapping changes in the soil resistivity as a function of space and time. The ERT tomographs are compared with induction well logs, formation temperature logs and lithologic logs. These comparisons suggest that the ERT tomographs mapped the formation regions invaded by the steam flood. The data also suggest that steam invasion was limited in vertical extent to a gravel horizon at depth of approximately 43 m. The tomographs show that with time, the steam invasion zone extended laterally to all areas monitored by the ERT technique.

Ramirez, A.; Daily, W.; LaBrecque, D.; Owen, E.; Chestnut, D.

1993-01-01

100

Electrical resistivity response due to elastic-plastic deformations  

SciTech Connect

The electrical resistivity of many materials is sensitive to changes in the electronic band configurations surrounding the atoms, changes in the electron-phonon interaction cross-sections, and changes in the density of intrinsic defect structures. These changes are most directly dependent on interatomic measures of relative deformation. For this reason, a model for resistivity response is developed in terms of interatomic measures of relative deformation. The relative deformation consists of two terms, a continuous function to describe the recoverable displacement between two atoms in the atomic lattice structure and a functional to describe the nonrecoverable displacement between two atoms as a result of interatomic discontinuities from dislocation kinetics. This model for resistivity extends the classical piezoresistance representation and relates electric resistance change directly to physical mechanisms. An analysis for the resistivity change of a thin foil ideally embedded in a material that undergoes elastic-plastic deformation is presented. For the case of elastic deformations, stress information in the material surrounding the thin foil is inferred for the cases of pure strain coupling boundary conditions, pure stress coupling boundary conditions, and a combination of stress-strain coupling boundary conditions. 42 refs., 4 figs.

Stout, R.B.

1987-01-01

101

Electrical resistance tomography used to monitor subsurface steam injection  

SciTech Connect

We used electrical resistance tomography (ERT) to map the subsurface distribution of a steam flood as function of time as part of a prototype environmental restoration process performed by the Dynamic Underground Stripping Project. We evaluated the capability of ERT to monitor changes in the soil resistivity during the steam injection process using a dipole-dipole measurement technique to measure the bulk electrical resistivity distribution in the soil mass. The injected steam caused changes in the soil`s resistivity because the steam displaced some of the native pore water, increased the pore water and soil temperatures and changed the ionic content of the pore water. We could detect the effects of steam invasion by mapping changes in the soil resistivity as a function of space and time. The ERT tomographs are compared with induction well logs, formation temperature logs and lithologic logs. These comparisons suggest that the ERT tomographs mapped the formation regions invaded by the steam flood. The data also suggest that steam invasion was limited in vertical extent to a gravel horizon at depth of approximately 43 m. The tomographs show that with time, the steam invasion zone extended laterally to all areas monitored by the ERT technique.

Ramirez, A.; Daily, W.; Owen, E.; Chesnut, D. [Lawrence Livermore National Lab., CA (United States); LaBrecque, D. [Arizona Univ., Tucson, AZ (United States)

1992-04-01

102

A unique data acquisition system for electrical resistance tomography  

SciTech Connect

Unique capabilities are needed in instrumentation used for acquiring data to do electrical resistance tomography (ERT). A data acquisition system is described which has a good combination of the required capabilities and yet is field rugged and user friendly. The system is a multichannel detector for high data rates, can operate over a wide range of load conditions, will measure both in phase and quadrature resistance at frequencies between 0.0007 Hz and 8 kHz. The system has been used in both the field and laboratory to collect data with a typical accuracy between 1 and 10%.

Daily, W.; Ramirez, A. [Lawrence Livermore National Lab., CA (United States); Zonge, K. [Zonge Engineering, Tucson, AZ (United States)

1996-01-04

103

Mathematical modeling of thermal operating regimes of electric resistance furnaces  

NASA Astrophysics Data System (ADS)

A physicomathematical model making it possible to calculate thermal regimes of electric resistance furnaces has been proposed. The model is suitable for description of linings and heated products of different types. It includes, as components, the following models: those of thermal-radiation transfer in the furnace’s workspace, of nonstationary heating of target products, of nonstationary heating of the furnace lining, and of external heat exchange of the furnace’s enclosing structures. The distinctive features of a numerical method for solution of the proposed model are discussed. An example of calculation of a chamber electric resistance furnace for the cases where it is lined with fireclay brick and lightweight fibrous materials is discussed. It is shown that replacement of the lining by a fibrous one improves the thermal operating efficiency for this type of furnace 2-2.5 times.

Grinchuk, P. S.

2010-03-01

104

The temperature-dependent electrical resistivities of the alkali metals  

Microsoft Academic Search

This review contains a comprehensive examination of all modern measurements and calculations of the temperature-dependent electrical resistivity rho(T) for the alkali metals-and especially potassium (K)-from their melting points down to below 0.1 K. The simplicity of the electronic structures of these metals makes them unique for testing our fundamental understanding of rho(T). At all temperatures down to a few K,

Jack Bass; William P. Pratt Jr.; Peter A. Schroeder

1990-01-01

105

Electrical resistivity of amorphous simple metals at moderately low temperatures  

NASA Astrophysics Data System (ADS)

The dependence of electrical resistivity ?(T) on temperature T in a region of moderate temperatures is considered for amorphous simple metals. It is shown within the Faber-Ziman theory that the ratio [?(T)-?(0)]/T2 has a maximum in the temperature region 10 K<=T<=100 K The theory is illustrated by numerical calculations performed for hard-sphere models of amorphous Mg and Zn.

Krasny, Yu. P.; Krawczyk, J.; Kovalenko, N. P.; Shvets, V. T.

1999-09-01

106

Temporal variations in the electrical resistivity of the Earth's crust  

NASA Astrophysics Data System (ADS)

An electrical resistivity monitoring experiment was conducted on a portion of the San Andreas fault near Hollister, California, in 1979 and early 1980. Receiving dipoles up to 20 km away from a 140-A 2-km transmitting dipole were used to monitor apparent resistivities with accuracies as high as 0.1% for some of the sites. Several of the transmitter-receivers clearly show long-term changes in resistivity greater than the data errors; annual variations at a site outside the fault zone exceed 10%, and sites in the fault zone show month to month changes of a few percent. There are also significant variations in the vicinity of the transmitter which would be expected to produce correlated changes at other sites, but this was not observed in the data. There were no earthquakes of magnitudes greater than 3.0 during this period of high-accuracy monitoring so that no conclusions can be drawn about changes in resistivity associated with major strain events. Future experiments to relate resistivity changes to earthquakes must not only have high sensitivity but must also be designed to distinguish such an event from normal background fluctuations that we have measured. Unless the resistivity variations associated with the event are of the order of several percent their detection will be a truly formidable task.

Morrison, H. F.; Fernandez, R.

1986-10-01

107

Dilatometric and electrical resistivity measurements in various phases of Nitinol  

NASA Astrophysics Data System (ADS)

Transformation characteristics of near equiatomic, prior cold worked Nitinol have been studied through thermomechanical analysis and electrical resistivity measurements, using TMA-50 and a four-probe setup, respectively. The dilatometric and electrical resistivity curves are obtained for the samples heat-treated between 300 and 600 degrees C. Examination of the dilation curves show that, in the martensitic phase there is positive thermal expansion where as, during M yields A transformation there is also uniaxial contraction till Af. In the austenitic phase there is positive thermal expansion and these thermal expansion values agree with the published values for respective phases. While cooling, at Ms uniaxial expansion starts and this continues till Mf is reached. In the present work the R-phase and associated hysteresis has also been investigated. On cooling from A-phase, uniaxial expansion is found to start from Rs and it stops at Rf. The transformation temperatures determined in this method agree very closely with those values obtained using electrical resistivity probe. Hysteresis area is found to be smaller in the A $ARLR M transformation. The area under hysteresis loop associated with R-phase is found to be a constant against thermal cycling. Certain applications like clamps and splints require a large hysteresis loop, while some solid sate actuators require relatively smaller hysteresis loops. An attempt is made to explain R-phase transformation in terms of thermo-mechanical data.

Uchil, Jayagopal; Mohanchandra, K. P.; Mahesh, K. K.; Ganesha, Kumara K.

1999-07-01

108

A geostatistically based inverse model for electrical resistivity surveys and its applications to vadose zone hydrology  

Microsoft Academic Search

A sequential, geostatistical inverse approach was developed for electrical resistivity tomography (ERT). Unlike most ERT inverse approaches, this new approach allows inclusion of our prior knowledge of general geological structures of an area and point electrical resistivity measurements to constrain the estimate of the electrical resistivity field. This approach also permits sequential inclusion of different data sets, mimicking the ERT

T.-C. Jim Yeh; S. Liu; R. J. Glass; K. Baker; J. R. Brainard; D. Alumbaugh; D. LaBrecque

2002-01-01

109

Carrier profiling of individual Si nanowires by scanning spreading resistance microscopy.  

PubMed

Individual silicon nanowires (NWs) doped either by ion implantation or by in situ dopant incorporation during NW growth were investigated by scanning spreading resistance microscopy (SSRM). The carrier profiles across the axial cross sections of the NWs are derived from the measured spreading resistance values and calibrated by the known carrier concentrations of the connected Si substrate or epi-layer. In the case of the phosphorus ion-implanted and subsequently annealed NWs, the SSRM profiles revealed a radial core-shell distribution of the activated dopants. The carrier concentration close to the surface of a phosphorus-doped NW is found to be by a factor of 6-7 higher than the value in the core and on average only 25% of the implanted phosphorus is electrically active. In contrast, for the in situ boron-doped NW the activation rate of the boron atoms is significantly higher than for phosphorus atoms. Some specific features of SSRM experiments of Si NWs are discussed including the possibility of three-dimensional measurements. PMID:20014820

Ou, Xin; Kanungo, Pratyush Das; Kögler, Reinhard; Werner, Peter; Gösele, Ulrich; Skorupa, Wolfgang; Wang, Xi

2010-01-01

110

The evaluation of arc erosion on electrical contacts using three-dimensional surface profiles  

Microsoft Academic Search

Three-dimensional surface profiling is a useful technique for the evaluation of electrical contact erosion. A review is given of the various methods by which a 3-D surface profile can be measured, and numerical techniques are described which can be used to analyze electrical contacts to define erosion in terms of volume and height changes. Experimental data on the rate of

John W. McBride; Kevin J. Cross; Suleiman M. Abu Sharkh

1996-01-01

111

The effect of temperature on the electrical resistivity of electrodeposited nanocrystalline materials  

Microsoft Academic Search

The electrical resistivity as a function of temperature (4K to 773K) of several electrodeposited nanocrystalline materials (Ni, Ni-Fe, Co) has been examined. The contribution of the grain boundaries to the electrical resistivity was quantified in terms of a specific grain boundary resistivity, which was found to be similar to previous reported values of specific grain boundary resistivity of copper and

Jonathan Lawrence McCrea

2001-01-01

112

Characterization and monitoring of subsurface processes using parallel computing and electrical resistivity imaging  

Microsoft Academic Search

This newsletter discusses recent advancement in subsurface resistivity characterization and monitoring capabilities. The BC Cribs field desiccation treatability test resistivity monitoring data is use an example to demonstrate near-real time 3D subsurface imaging capabilities. Electrical resistivity tomography (ERT) is a method of imaging the electrical resistivity distribution of the subsurface. An ERT data collection system consists of an array of

Timothy C. Johnson; Michael J. Truex; Dawn M. Wellman; Justin Marble

2011-01-01

113

Electrical Resistivity Imaging of Subterranean Void Space for Assessment of Endangered Species Habitat  

NASA Astrophysics Data System (ADS)

The challenge of identifying and delineating subterranean habitat for endangered species in karst environments has been addressed through the application of near-surface geophysical techniques. Electrical resistivity imaging (ERI) in both galvanic DC and capacitance-coupled modes has been applied to the problem of imaging subsurface voids, potentially conducive to karst invertebrate habitat, in two distinctly different geologic, geophysical, and environmental settings. Surveys were conducted in extrusive volcanic terrain on the south shore of Kauai, Hawaii, a site known for lava tube formation, and in limestone karst terrain in central Texas. The two study sites were distinctly different in their geophysical settings in terms of surface layer and subsurface background resistivities, values at the Kauai site ranging from 1000 - 5000 ohm-meters and at the Texas site 100 - 800 ohm-meters, values reflecting differing lithology, porosity, and pore fluid content. An Advanced Geosciences Inc. (AGI) Supersting R8 DC resistivity system was the primary instrumentation utilized for both surveys, with a capacitance-coupled Geometrics Inc. OhmMapper TR-2 system utilized on the Kauai site for reconnaissance profiles. Opportunities existed for direct comparisons of Supersting and OhmMapper pseudo- section profiles. Supersting lines were acquired with a mixed array combining the horizontal resolution sensitivity of the dipole-dipole array with the vertical resolution sensitivity of the Inverse Schlumberger array. At both sites, surveys were conducted over known and mapped cave passage for validation of the techniques. Forward simulation modeling was conducted to verify resistivity anomaly signatures of known void spaces. Results were highly encouraging and serve to reinforce the karst-imaging capabilities of electrical resistivity, especially when mixed array types are utilized.

Weissling, B. P.; White, K.

2007-12-01

114

Electrical Resistivity Imaging for Studying Dynamics of Vadose Zone Processes  

NASA Astrophysics Data System (ADS)

Determining the spatial distribution of subsurface hydrologic properties is critical to developing efficient groundwater management strategies. Electrical resistivity imaging (ERI) provides continuous maps of the subsurface electrical conductivity, which can be related to water content, making it particularly useful to groundwater studies. We present an application of ERI to monitoring infiltration in the top 20 m of the subsurface at the Harkins Slough Recharge Pond, located in an agricultural region on the northern California coast. The purpose of the recharge pond is two-fold: to store diverted storm-flow run-off to meet groundwater delivery demands and to replenish underlying aquifers, which have been overdrawn for several decades, allowing saltwater intrusion. Operators of the pond have rights to divert 2.5e6 m3 of surface water to the pond each year, but decreasing infiltration rates during diversion reduces the operational efficiency, only allowing infiltration of ~1e6 m3 each year. It is hypothesized that deposition of fine-sediments from diverted water, run-off from adjacent fields, and/or microbial activity reduce the hydraulic conductivity over time by clogging pore spaces. As part of an effort to better understand the hydrologic processes controlling infiltration to improve operational efficiency of the recharge pond we conducted time-lapse ERI experiments to monitor infiltration processes beneath the pond during the winters of 2008-2009 and 2009-2010. Each year measurements were made using four 3-m long permanent probes installed in the base of the pond in a T-shape configuration, with 20 m between each probe. The probes allow for monitoring of the conductivity profile to a depth of 2 m; the top meter of each probe monitors bulk conductivity of the pond water. In addition, a number of surface electrodes were laid out in lines between the four probes. In 2008-2009, 20-m lines were used. In 2009-2010, three lines of lengths 10 m, 65 m, and 75 m were deployed. Acquisition geometries designed to target different regions of the subsurface were used to acquire measurements every 1.5 hours. In 2008-2009 ~2000 data sets were acquired; each data set included measurements from probes and surface lines. In 2009-2010 ~1000 data sets were acquired. Data were processed using an extended Kalman filter (EKF) approach. The EKF was chosen for processing time-series ERI data because it models evolution of the physical system and the observation process, incorporating previous information into data-inversion at each time-step. In this application, the first for surface-based ERI field data, we modify the classical Kalman filter cost functional to incorporate spatial smoothing and impose an update constraint to account for slow state evolution with respect to the sampling interval. Results identified more hydrologic complexity than was originally assumed and indicated that processes in the top 0.5 m of the subsurface control infiltration rates. The results of ERI monitoring demonstrate that integrating geophysics into hydrologic studies can provide increased information about spatial and temporal evolution of vadose zone processes.

Mitchell, V.; Pidlisecky, A.; Knight, R. J.

2010-12-01

115

The `L' Array, a method to model 3D Electrical Resistivity Tomography (ERT) data  

NASA Astrophysics Data System (ADS)

The electrical resistivity tomography (ERT) is a method designed to calculate the distribution of apparent electrical resistivities in the subsoil by means of a great number of observations with the aim of determining an electrical image displaying the distribution of true resistivities in the subsoil. Such process can be carried out to define 2D or 3D models of the subsurface. For a 3D ERT, usually, the electrodes are placed in a squared grid keeping the distance between adjacent electrodes constant in the x and y directions. Another design employed, consists of a series of parallel lines whose space inter-lines must be smaller or equal to four times the electrode separation. The most common electrode arrays frequently employed for this type of studies are the pole-pole, pole-dipole and dipole-dipole. Unfortunately, ERT surface sampling schemes are limited by physical conditions or obstacles, like buildings, highly populated urban zones, and geologic/topographic features, where the lines of electrodes cannot be set. However, it is always necessary to characterize the subsoil beneath such anthropogenic or natural features. The ‘L’ shaped array has the main purpose to overcome such difficulties by surrounding the study area with a square of electrode lines. The measurements are obtained by switching automatically current and potential electrodes from one line to the other. Each observation adds a level of information, from one profile to the other. Once the total levels of data are completed, the opposite ‘L’ array can be measured following the same process. The complete square is computed after the parallel profiles are observed as well. At the end, the computed resistivities are combined to form a 3D matrix of observations. Such set of data can be inverted to obtain the true resistivity distribution at depth in the form of a working cube, which can be interpreted. The method was tested with theoretical models, which included a set of two resistive cubes with different position, a fault and a tunnel. Results are quite encouraging; shapes and position of bodies are preserved. Unfortunately inverted resistivities are lower than the theoretical ones, mainly due to the array effects. Two field examples are presented, the subsurface study beneath a National Monument (The Morelia City Cathedral) to detect possible Colonial tunnels, and a fracture pattern characterization in one of the University of the City Mexico campus (Casa Libertad, Eastern campus), where such geological feature affects its infrastructure.

Chavez Segura, R. E.; Chavez-Hernandez, G.; Delgado, C.; Tejero-Andrade, A.

2010-12-01

116

Connection equation and shaly-sand correction for electrical resistivity  

USGS Publications Warehouse

Estimating the amount of conductive and nonconductive constituents in the pore space of sediments by using electrical resistivity logs generally loses accuracy where clays are present in the reservoir. Many different methods and clay models have been proposed to account for the conductivity of clay (termed the shaly-sand correction). In this study, the connectivity equation (CE), which is a new approach to model non-Archie rocks, is used to correct for the clay effect and is compared with results using the Waxman and Smits method. The CE presented here requires no parameters other than an adjustable constant, which can be derived from the resistivity of water-saturated sediments. The new approach was applied to estimate water saturation of laboratory data and to estimate gas hydrate saturations at the Mount Elbert well on the Alaska North Slope. Although not as accurate as the Waxman and Smits method to estimate water saturations for the laboratory measurements, gas hydrate saturations estimated at the Mount Elbert well using the proposed CE are comparable to estimates from the Waxman and Smits method. Considering its simplicity, it has high potential to be used to account for the clay effect on electrical resistivity measurement in other systems.

Lee, Myung W.

2011-01-01

117

Determining and Interpreting Resistive Electric Circuit Concepts Test (DIRECT)  

NSDL National Science Digital Library

This 29-question research-based multiple-choice test is designed to evaluate students' reasoning regarding direct current resistive electric circuits. The test may be administered to students in algebra- or calculus-based introductory physics courses in high school or university settings. The test is based on investigations of students' difficulties with direct current circuits and should be given in a 30-minute period. Statistical results have shown the survey to be reliable and valid. A summary of the construction and analysis of the survey is available in, Studentsâ understanding of direct current resistive electrical circuits, Am. J. Phys. 72 (1), 98-115 (2004). Details are provided in Paula Engelhardt's dissertation, Examining students' understanding of electrical circuits through multiple-choice testing and interviews. This assessment is free for use by instructors in their classroom. However, as it takes years of development effort to create and validate reliable assessment instruments, the file is password-protected. Furthermore, the author requests that 1. students are not given copies following examination; and 2. none of the questions are incorporated into web-based question delivery systems without adequate security to prevent printing or unauthorized access by students. To obtain the password, please send a request with your name, email, institution, and a link to a page at your institution that confirms you are an instructor.

Engelhardt, Paula V.; Beichner, Robert J.

2013-03-03

118

Electrical resistivity tomography monitoring of permafrost in solid rock walls  

NASA Astrophysics Data System (ADS)

This article describes the first attempt to conduct electrical resistivity tomography (ERT) in solid permafrost-affected rock faces. Electrode design, instrument settings, and processing routines capable of measuring under relevant conditions were developed. Four transects, with NW, NE, east (E) and south (S) aspects, were installed in solid rock faces between Matter Valley and Turtmann Valley, Switzerland, at 3070-3150 m above sea level. DC resistivity in the transects was measured repeatedly during the summer and compared by applying a time-lapse inversion routine. Resistivity values were calibrated using observed rock surface conditions of thawed, damp rocks (1-8 k? m), deeply frozen rocks (18-80 k? m), and the transition from damp thawed to frozen rocks (8-18 k? m). Mean surface layer resistivities of transects respond to air temperatures below 0°C with a rapid increase by a factor of 1.4 to 2.9 from values of 12-15 k? m to values of 22-31 k? m. Rock layers at depths of 2-6 m display a general trend of resistivity decrease in summer, corresponding to a persistent thawing process. Their response to anomalously cool August temperatures occurs with a time lag of 2 to 4 weeks. Only transects E, NE and NW display persistent, high-resistivity permafrost bodies (>50 k? m) mostly at depths of 6-10 m. The maximum thaw depth of a continuous thawing front above permafrost is 6 m. However, the ERT results emphasize the role of heat transfer by deep-reaching cleft water systems. Thus permafrost occurs in lenses rather than layers. ERT provides rapid detection of ice and water distribution in permafrost-affected bedrock.

Krautblatter, Michael; Hauck, Christian

2007-06-01

119

Electrical resistivity tomography revealing the internal structure of monogenetic volcanoes  

NASA Astrophysics Data System (ADS)

activity of individual monogenetic volcanoes usually lasts a few days or weeks. However, their short lifetime does not always mean that their dynamics and structure are simple. Monogenetic cones construction is rarely witnessed from the beginning to the end, and conditions for observing their internal structure are hardly reached. We provide high-resolution electrical resistivity sections (10 m electrode spacing) of three monogenetic cones from northeastern Spain, comparing our results to geological observations to interpret their underground continuation. The 100 m maximum depth of exploration provides information on almost the entire edifices, highlighting the relationships between Strombolian and hydromagmatic deposits in two multiphase edifices. A main observation is a column of distinct resistivity centered on the Puig d'Adri volcano, which we interpret as the eruptive conduit. This method can provide valuable information on the past volcanic dynamics of monogenetic volcanic fields, which has real implications for the forecast of future activity.

Barde-Cabusson, StéPhanie; Bolós, Xavier; Pedrazzi, Dario; Lovera, Raul; Serra, Guillem; Martí, Joan; Casas, Albert

2013-06-01

120

Optical device with low electrical and thermal resistance bragg reflectors  

DOEpatents

A compound-semiconductor optical device and method. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors.

Lear, Kevin L. (Albuquerque, NM)

1996-01-01

121

Optical device with low electrical and thermal resistance Bragg reflectors  

DOEpatents

A compound-semiconductor optical device and method are disclosed. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors. 16 figs.

Lear, K.L.

1996-10-22

122

Electrical Resistivities of Nonstoichiometric Cerium Hydride Single Crystals  

Microsoft Academic Search

Electrical resistivities as a function of temperature (?130° to 25°C) were determined on single crystals of cerium hydride ranging in composition from CeH1.94&sngbnd;CeH2.85. Measurements were performed in an inert-atmosphere dry box using the four-point probe technique. Cerium hydride exhibited metallic behavior in the range CeH1.9&sngbnd;CeH2.7. However, at a composition of about CeH2.85, a positive temperature coefficient of conductivity indicative of

G. G. Libowitz; J. G. Pack

1969-01-01

123

Marine seismic profiling and shallow marine sand resistivity investigations in Jervis Bay, NSW, Australia  

NASA Astrophysics Data System (ADS)

A marine continuous seismic profiling (CSP) study and a resistivity study of vibrocore samples of shallow marine sands were undertaken in Jervis Bay, NSW, Australia, to characterise the seabed. The CSP study also included Crookhaven Bight, adjacent to Jervis Bay facing north-east to the ocean. The overall aims were: (i) to estimate sediment thickness, and surficial sediment resistivity (upper 3m) at selected sites, to explore the features of the bedrock topography; and (ii) combined with upper layer (sea water) parameters that can be accurately measured, to provide a simplified geo-electrical model of the ground (sea water/seabed) to support interpretation of airborne electromagnetic survey data. The results of the CSP studies indicate very dense sands (tighter packing) and variably weathered sandstones, suggesting variable geological conditions below the seabed. The bedrock surface was also highly irregular in places suggesting an erosional pulse(s) under rapidly falling sea levels at various times in the past. Bedrock was found to form the sea floor in some locations and is deeply incised by palaeochannels extending to 62m below sea level in the Crookhaven Bight and Jervis Bay entrance areas. The laboratory resistivity values, obtained from four electrode measurements on seawater saturated subsamples, averaged 0.88?m (20°C). Inter- and intra-site changes in mineralogy (shell/sand), grain packing, grain size, grain shape, cohesion, and inferred porosity were thought to be responsible for minor variations in resistivity. Archie Equation plots showed some scatter, but the data indicate a cementation factor of ~1.6 and an average formation factor of 4.3 for the suites of sands. These values are consistent with values cited in the literature.

Vrbancich, Julian; Whiteley, Robert J.; Emerson, Don W.

2011-06-01

124

Reservoir characterization combining elastic velocities and electrical resistivity measurements  

NASA Astrophysics Data System (ADS)

The elastic and electric parameters of rocks that can be obtained from seismic and electromagnetic data depend on porosity, texture, mineralogy, and fluid. However, seismic data seldom allow us to accurately quantify hydrocarbon saturation. On the other hand, in the case of common reservoir rocks (i.e., sandstones and carbonates), resistivity strongly depends on porosity and saturation. Therefore, the recent progress of controlled-source-electromagnetic (CSEM) methods opens new possibilities in identifying and quantifying potential hydrocarbon reservoirs, although its resolution is much lower than that of seismic data. Hence, a combination of seismic and CSEM data arguably offers a powerful means of finally resolving the problem of remote sensing of saturation. The question is how to combine the two data sources (elastic data and electrical resistivity data) to better characterize a reservoir. To address this question, we introduce the concept of P-wave impedance and resistivity templates as a tool to estimate porosity and saturation from well log data. Adequate elastic and resistivity models, according to the lithology, cementation, fluid properties must be chosen to construct these templates. These templates can be upscaled to seismic and CSEM scale using Backus average for seismic data, and total resistance for CSEM data. We also measured velocity and resistivity in Fontainebleau samples in the laboratory. Fontainebleau formation corresponds to clean sandstones (i.e., low clay content). We derived an empirical relation between these P-wave velocity and resistivity at 40MPa effective pressure, which is around 3 km depth at normal pressure gradients. We were not able to test if this relation could be used at well or field data scales (once appropriate upscaling was applied), since we did not have a field dataset over a stiff sandstone reservoir. A relationship between velocity and resistivity laboratory data was also found for a set of carbonates. This expression was quadratic, and not linear as in the case of Fontainebleau sandstones. There are other factors that influence this relationship in the case of these carbonates, which include pore geometry, and amount of micritic cement. We observed that the expression is almost linear, but it deviates as we approach lower resistivities. This deviation can be explained by the presence of stiff pores such as moldic or intra-granular pores, which causes high velocity but low resistivity values when water-saturated. In the same way, the effect of micrite cement on velocity is stronger than its effect on resistivity, and that also is responsible for some of the scatter that we observe. We also modeled both velocity and resistivity using self-consistent approximation with the same pore or inclusion geometries in both carbonate and sandstone laboratory datasets. In the case of carbonates, we found that we had to include needle-like pores to explain the low resistivity but high velocities. Needle is one of the geometries that allow us to have connected stiff pores. However, we also found that a fraction of compliant pores also had to be included in order to explain the velocity measurements on the carbonate dataset. The self-consistent model also approximated well the velocity and resistivity laboratory measurements on the Fontainebleau sandstones, using similar aspect ratios for both the velocity and the resistivity. As far as semi-empirical and empirical models, we observed how the stiff-sand model fit well the Fontainebleau data at 40MPa, including S-wave velocities. The Raymer-Hunt-Gardner relation also did a good job at predicting P-wave velocity. Archie's equation with cementation exponent between 1.6 and 2.1 fits the resistivity measurements on the Fontainebleau sandstones. These two relationships can be combined to create a resistivity---P-wave velocity transform for this dataset. When we attempted to use CSEM data to limit the shallow and low-frequency acoustic impedance trend for seismic inversion, we found that appropriate elastic and resistivity models must be chosen in

Gomez, Carmen Teresa

125

Improvement of electrical resistivity tomography for leachate injection monitoring  

SciTech Connect

Leachate recirculation is a key process in the scope of operating municipal waste landfills as bioreactors, which aims to increase the moisture content to optimize the biodegradation in landfills. Given that liquid flows exhibit a complex behaviour in very heterogeneous porous media, in situ monitoring methods are required. Surface time-lapse electrical resistivity tomography (ERT) is usually proposed. Using numerical modelling with typical 2D and 3D injection plume patterns and 2D and 3D inversion codes, we show that wrong changes of resistivity can be calculated at depth if standard parameters are used for time-lapse ERT inversion. Major artefacts typically exhibit significant increases of resistivity (more than +30%) which can be misinterpreted as gas migration within the waste. In order to eliminate these artefacts, we tested an advanced time-lapse ERT procedure that includes (i) two advanced inversion tools and (ii) two alternative array geometries. The first advanced tool uses invariant regions in the model. The second advanced tool uses an inversion with a 'minimum length' constraint. The alternative arrays focus on (i) a pole-dipole array (2D case), and (ii) a star array (3D case). The results show that these two advanced inversion tools and the two alternative arrays remove almost completely the artefacts within +/-5% both for 2D and 3D situations. As a field application, time-lapse ERT is applied using the star array during a 3D leachate injection in a non-hazardous municipal waste landfill. To evaluate the robustness of the two advanced tools, a synthetic model including both true decrease and increase of resistivity is built. The advanced time-lapse ERT procedure eliminates unwanted artefacts, while keeping a satisfactory image of true resistivity variations. This study demonstrates that significant and robust improvements can be obtained for time-lapse ERT monitoring of leachate recirculation in waste landfills.

Clement, R., E-mail: remi.clement@hmg.inpg.f [Laboratoire d'Etude des Transferts en Hydrologie et Environnement, LTHE, UMR 5564, CNRS, INPG, IRD, UJF, B.P. 53, 38041, Grenoble Cedex 9 (France); Descloitres, M. [Laboratoire d'Etude des Transferts en Hydrologie et Environnement, LTHE, UMR 5564, CNRS, INPG, IRD, UJF, B.P. 53, 38041, Grenoble Cedex 9 (France); Guenther, T., E-mail: Thomas.Guenther@liag-hannover.d [Leibniz Institute for Applied Geophysics, Stilleweg 2, D-30655 Hannover (Germany); Oxarango, L. [Laboratoire d'Etude des Transferts en Hydrologie et Environnement, LTHE, UMR 5564, CNRS, INPG, IRD, UJF, B.P. 53, 38041, Grenoble Cedex 9 (France); Morra, C., E-mail: christophemorra@yahoo.f [PROKHEM/Floralis, 6 allee de Bethleem, 38610 Gieres (France); Laurent, J.-P.; Gourc, J.-P. [Laboratoire d'Etude des Transferts en Hydrologie et Environnement, LTHE, UMR 5564, CNRS, INPG, IRD, UJF, B.P. 53, 38041, Grenoble Cedex 9 (France)

2010-03-15

126

The effects of dopants on the electrical resistivity in lead magnesium niobate multilayer ceramic capacitors  

Microsoft Academic Search

Electrical resistivity studies were performed on multilayer ceramic capacitors (MLC) based on lead magnesium niobate and containing dopants of lead titanate, lead zinc niobate, and lead cobalt niobate. The results showed that lead titanate and\\/or lead zinc niobate had no effect on the electrical resistivity while lead cobalt niobate decreased the resistivity. In samples without lead cobalt niobate, the authors

D. D. Chang; H. C. Ling

1989-01-01

127

Dominant role of tunneling resistance in the electrical conductivity of carbon nanotube-based composites  

Microsoft Academic Search

The effect of nanotube\\/nanotube contact resistance on the electrical conductivity of carbon nanotube-based nanocomposites is studied. The tunneling resistance due to an insulating film of matrix material between crossing nanotubes is calculated by assuming a rectangular potential barrier in the insulating film. Monte Carlo simulations indicate that the tunneling resistance plays a dominant role in the electrical conductivity of composites,

Chunyu Li; Erik T. Thostenson; Tsu-Wei Chou

2007-01-01

128

Electrical resistivity tomography at the DOE Hanford site  

SciTech Connect

Recent work at the DOE Hanford site has established the potential of applying Electrical Resistivity Tomography (ERT) for early leak detection under hazardous waste storage facilities. Several studies have been concluded to test the capabilities and limitations of ERT for two different applications. First, field experiments have been conducted to determine the utility of ERT to detect and map leaks from underground storage tanks during waste removal processes. Second, the use of ERT for long term vadose zone monitoring has been tested under different field conditions of depth, installation design, acquisition mode/equipment and infiltration chemistry. This work involves transferring the technology from Lawrence Livermore National Laboratory (LLNL) to the Resource Conservation and Recovery Act (RCRA) program at the DOE Hanford Site. This paper covers field training studies relevant to the second application for long term vadose monitoring. Electrical resistivity tomography is a cross-borehole, imaging technique for mapping subsurface resistivity variations. Electrodes are placed at predetermined depths in an array of boreholes. Electrical current is introduced into one electrode pair located in one borehole while the resulting voltage change is detected between electrode pairs in other boreholes similar to a surface dipole-dipole array. These data are topographically inverted to image temporal resistivity contrasts associated with an infiltration event. Thus a dynamic plume is spatially mapped as a function of time. As a long-term vadose zone monitoring method, different field conditions and performance requirements exist than those for short term tank leak detection. To test ERT under these conditions, two vertical electrode arrays were constructed to a depth of 160 feet with a linear surface array between boreholes. The fielding was used to facilitate the technology transfer from LLNL to the Hanford RCRA program. Installation methods, commercial equipment and acquisition mode were evaluated to determine economic and technical feasibility to assist design of long-term monitoring networks. Preliminary results of the training test are presented. Until recently, vadose zone monitoring techniques could provide only local point or linear coverage for leak detection and thus, are used primarily under liquid collection systems at land disposal units. As developed by LLNL, ERT can provide areal coverage under waste treatment and storage facilities given the right conditions. Advantages of ERT to groundwater protection programs are explored along with suggestions for future uses where ERT can be employed today.

Narbutovskih, S.M.

1996-04-04

129

Use of electrical resistivity tomography to evaluate processes in soils  

NASA Astrophysics Data System (ADS)

Electrical resistivity tomography (ERT) is a non-invasive imaging technique capable of evaluating the distribution of electrical properties within a cross-section or volume of soil specimens. The technique provides an alternative for monitoring processes in soils that otherwise do not yield mechanical or density contrasts. This research presents the development and testing of 2D and 3D ERT imaging systems to map processes in soils and other porous media. The 2D ERT testing cell consisted of 16 electrodes placed along the perimeter of a circular section while the 3D ERT testing cell is composed of 64 electrodes distributed along four planes of the cylindrical testing cell. The 3D ERT testing cell also included 16 bender elements that were used to monitor S-wave propagation parameters to complement the electrical resistivity data. Two different tests were monitored with the ERT systems. The first test involved monitoring chemical diffusion in a 2D soil media by injecting 6 mL of 0.2 mol/L NaCl solution into tap water-saturated Ottawa sand. The ERT system successfully monitored the progression of the chemical diffusion over time. The second test images the injection of sodium pyrophosphate (SPP)-modified bentonite slurry in a sand specimen. Researchers at Purdue University developed this methodology with the intent to reduce liquefaction potential of loose saturated sands. Three tests were conducted to characterize the injected material and the injection processes: (i) electrical impedance analysis were conducted on the SPP-treated bentonite slurries to evaluate the reduction in resistivity with SPP concentration and time, (ii) viscosity measurements of the SPP-treated bentonite slurry were conducted to characterize the mechanical behavior of the slurry and show how increasing SPP concentration decreases and then regains slurry viscosity and (iii) the ERT system and bender elements were used to monitor the injection of bentonite slurry treated with 1% SPP in loose sand specimens. Results show the complementary nature of ERT and bender element data to successfully evaluate the injection process and the effect on the sand-saturated system.

Damasceno, Victor M.

130

THE VARIATION OF ELECTRICAL RESISTANCE WITH APPLIED POTENTIAL  

PubMed Central

Electrical resistance and polarization were measured during the passage of direct current across a single layer of protoplasm in the cells of Valonia ventricosa impaled upon capillaries. These were correlated with five stages of the P.D. existing naturally across the protoplasm, as follows: 1. A stage of shock after impalement, when the P.D. drops from 5 mv. to zero and then slowly recovers. There is very little effective resistance in the protoplasm, and polarization is slight. 2. The stage of recovery and normal P.D., with values from 8 to 25 mv. (inside positive). The average is 15 mv. At first there is little or no polarization when small potentials are applied in either direction across the protoplasm, nor when very large currents pass outward (from sap to sea water). But when the positive current passes inward there is a sudden response at a critical applied potential ranging from 0.5 to 2.0 volts. The resistance then apparently rises as much as 10,000 ohms in some cases, and the rise occurs more quickly in succeeding applications after the first. When the potential is removed there is a back E.M.F. displayed. Later there is also an effect of such inward currents which persists into the first succeeding outward flow, causing a brief polarization at the first application of the reverse potential. Still later this polarization occurs at every exposure, and at increasingly lower values of applied potentials. Finally there is a "constant" state reached in which the polarization occurs with currents of either direction, and the apparent resistance is nearly uniform over a considerable range of applied potential. 3. A state of increased P.D.; to 100 mv. (inside positive) in artificial sap; and to 35 or 40 mv. in dilute sea water or 0.6 M MgSO4. The polarization response and apparent resistance are at first about as in sea water, but later decrease. 4. A reversed P.D., to 50 mv. (outside positive) produced by a variety of causes, especially by dilute sea water, and also by large flows of current in either direction. This stage is temporary and the cells promptly recover from it. While it persists the polarization appears to be much greater to outward currents than to inward. This can largely be ascribed to the reduction of the reversed P.D. 5. Disappearance of P.D. caused by death, and various toxic agents. The resistance and polarization of the protoplasm are negligible. The back E.M.F. of polarization is shown to account largely for the apparent resistance of the protoplasm. Its calculation from the observed resistance rises gives values up to 150 mv. in the early stages of recovery, and later values of 50 to 75 mv. in the "constant" state. These are compared with the back E.M.F. similarly calculated from the apparent resistance of intact cells. The electrical capacitance of the protoplasm is shown by the time curves to be of the order of 1 microfarad per cm.2 of surface.

Blinks, L. R.

1930-01-01

131

Electrical resistivity imaging study of near-surface infiltration  

NASA Astrophysics Data System (ADS)

High resolution electrical resistivity images (ERI method) were obtained during vadose zone infiltration experiments on agricultural soils in cooperation with Cornell University's Agricultural Stewardship Program, Cooperative Extension of Suffolk County, Extension Education Center, Riverhead, New York [ as well as Cornell University's Long Island Horticultural Research & Extension Center (LIHREC) in Riverhead, New York]. One natural soil was also studied. Infiltration was monitored by means of image analysis of two-dimensional array resistivity generated by a Syscal Kid Switch resistivity system (Griffiths et al., 1990). The data was inverted with the computer program RES2DINV (Loke, 2004). The agricultural soils considered were Riverhead sandy loam (RdA), Haven loam (HaA), and Bridgehampton silt loam (BgA). The natural site was located in the Catskill Mountains of New York State. The soils there are classified as Schoharie silty clay loam. The electrical images of the three sites were compared against established soil properties, including particle size distribution, available water capacity, and soluble salts (from the literature), as well as against site-specific soil samples and penetrometer data, which were collected along with the geophysical measurements. This research evaluates the potential of acquiring high resolution, non-destructive measurements of infiltration in the uppermost 1.5 meter of the vadose zone. The results demonstrate that resistivity differences can detect infiltration in soils typical of the north-eastern United States. Temporal and spatial variations of soil water content in the upper 1.5 meters (relevant to agriculture) of the subsurface can be monitored successfully and non-destructively with ERI. The sensitivity of the method is higher in subsurface environments that demonstrate high overall apparent resistivity values (e.g. high sand content). Under conditions of increased soil heterogeneity, instead of the formation of a continuous water plume as occurred in the homogeneous agricultural soils, the location of the infiltrated water seems to be highly influenced by the soil heterogeneity, and the water front is scattered into discontinuous layers and travels in additional directions. The geophysical results during infiltration correlate well with soil compaction data. It follows that the ERI method can be used as a proxy for soil compaction and water content variations in agricultural applications. In a natural environment, ERI successfully maps the tree root zone of mature trees. Applications include continuous water content monitoring in high value cash crops, such as viticulture (precision agriculture).

Lampousis, Angelos

132

Challenges of using electrical resistivity method to locate karst conduits—A field case in the Inner Bluegrass Region, Kentucky  

NASA Astrophysics Data System (ADS)

Conduits serve as major pathways for groundwater flow in karst aquifers. Locating them from the surface, however, is one of the most challenging tasks in karst research. Geophysical methods are often deployed to help locate voids by mapping variations of physical properties of the subsurface. Conduits can cause significant contrasts of some physical properties that can be detected; other subsurface features such as water-bearing fractures often yield similar contrasts, which are difficult to distinguish from the effects of the conduits. This study used electrical resistivity method to search for an unmapped karst conduit that recharges Royal Spring in the Inner Bluegrass karst region, Kentucky, USA. Three types of resistivity techniques (surface 2D survey, quasi-3D survey, and time-lapse survey) were used to map and characterize resistivity anomalies. Some of the major anomalies were selected as drilling targets to verify the existence of the conduits. Drilling near an anomaly identified by an electrical resistivity profile resulted in successful penetration of a major water-filled conduit. The drilling results also suggest that, in this study area, low resistivity anomalies in general are associated with water-bearing features. However, differences in the anomaly signals between the water-filled conduit and other water-bearing features such as water-filled fracture zones were undistinguishable. The electrical resistivity method is useful in conduit detection by providing potential drilling targets. Knowledge of geology and hydrogeology about the site and professional judgment also played important roles in locating the major conduit.

Zhu, Junfeng; Currens, James C.; Dinger, James S.

2011-11-01

133

Electrically active recoil profiles of Al in silicon  

NASA Astrophysics Data System (ADS)

Depth profiles of the acceptor concentrations in disordered and undisordered silicon have been studied after recoil implantation of Al. The Si samples have been disordered by multiple ion implantation of He ions in the energy range from 30 to 150 keV. Recoil implantation has been carried out in the Al/Si(p) system using 100 keV Ar ions. These results have been compared with profiles after direct implantation of Al ions. The acceptor concentration profiles have been obtained from capacitance-voltage (C-V) measurements. Additionally the influence of the annealing on the X-ray diffraction patterns of Al/Si(p) systems has been investigated.

Paprocki, K.; Brylowska, I.

1986-08-01

134

Optimum doping profile for minimum ohmic resistance and high-breakdown voltage  

Microsoft Academic Search

The optimum doping profile of a lightly doped layer that introduces the minimum series resistance and sustains a given junction breakdown voltage is derived. The theory applies to a one-dimensional Schottky diode and qualitatively to the collector or drain doping profiles of transistors. The minimum series resistance is found to be about 3.7 × 10-9Vmin{B}max{2.6}?.cm2for an n silicon layer. The

Chenming Hu

1979-01-01

135

A comprehensive model for the electrical nanocontact on germanium for scanning spreading resistance microscopy applications  

NASA Astrophysics Data System (ADS)

Quantitative carrier profiling represents a key element in the process development of future nanoelectronic devices. During the last decade, scanning spreading resistance microscopy (SSRM) has evolved as the method of choice for two-dimensional carrier mapping due to its unique spatial resolution and high sensitivity when applied to silicon (Si)-based devices. While the electrical nanocontact between a SSRM probe and Si is well documented, the insight is insufficient to understand or make predictions about the properties of the SSRM contact in case of high-mobility germanium (Ge) samples. Therefore, we present in this paper a model describing this contact in more detail, taking into account the effects of the applied pressure as this leads to the formation of a ?-Sn pocket right underneath the probe and a spatially non-homogeneous bandgap reduction in the underlying Ge. The resistance probed through the resulting Schottky contact is further influenced by the dimensions of the nanocontact and in particular by the spatial extent of the surface states which are present at the cross-sectional surface. To account for the low-bias IV-characteristics of n-Ge, the model also includes trap-assisted tunneling. Using this model, we are able to describe the role of probe properties such as probe radius and resistivity on the shape (steepness, saturation, non-linearity) of the Ge calibration curve. We demonstrate experimentally and by simulation that low-resistivity probes are indispensable for a high sensitivity when applying SSRM to highly doped samples.

Schulze, Andreas; Verhulst, Anne S.; Nazir, Aftab; Hantschel, Thomas; Eyben, Pierre; Vandervorst, Wilfried

2013-03-01

136

Embryonic carcinoma cells show specific dielectric resistance profiles during induced differentiation.  

PubMed

Induction of differentiation in cancer stem cells by drug treatment represents an important approach for cancer therapy. The understanding of the mechanisms that regulate such a forced exit from malignant pluripotency is fundamental to enhance our knowledge of tumour stability. Certain nucleoside analogues, such as 2'-deoxy-5-azacytidine and 1?-arabinofuranosylcytosine, can induce the differentiation of the embryonic cancer stem cell line NTERA 2 D1 (NT2). Such induced differentiation is associated with drug-dependent DNA-damage, cellular stress and the proteolytic depletion of stem cell factors. In order to further elucidate the mode of action of these nucleoside drugs, we monitored differentiation-specific changes of the dielectric properties of growing NT2 cultures using electric cell-substrate impedance sensing (ECIS). We measured resistance values of untreated and retinoic acid treated NT2 cells in real-time and compared their impedance profiles to those of cell populations triggered to differentiate with several established substances, including nucleoside drugs. Here we show that treatment with retinoic acid and differentiation-inducing drugs can trigger specific, concentration-dependent changes in dielectric resistance of NT2 cultures, which can be observed as early as 24 hours after treatment. Further, low concentrations of nucleoside drugs induce differentiation-dependent impedance values comparable to those obtained after retinoic acid treatment, whereas higher concentrations induce proliferation defects. Finally, we show that impedance profiles of substance-induced NT2 cells and those triggered to differentiate by depletion of the stem cell factor OCT4 are very similar, suggesting that reduction of OCT4 levels has a dominant function for differentiation induced by nucleoside drugs and retinoic acid. The data presented show that NT2 cells have specific dielectric properties, which allow the early identification of differentiating cultures and real-time label-free monitoring of differentiation processes. This work might provide a basis for further analyses of drug candidates for differentiation therapy of cancers. PMID:23533658

Öz, Simin; Maercker, Christian; Breiling, Achim

2013-03-22

137

Embryonic Carcinoma Cells Show Specific Dielectric Resistance Profiles during Induced Differentiation  

PubMed Central

Induction of differentiation in cancer stem cells by drug treatment represents an important approach for cancer therapy. The understanding of the mechanisms that regulate such a forced exit from malignant pluripotency is fundamental to enhance our knowledge of tumour stability. Certain nucleoside analogues, such as 2?-deoxy-5-azacytidine and 1?-arabinofuranosylcytosine, can induce the differentiation of the embryonic cancer stem cell line NTERA 2 D1 (NT2). Such induced differentiation is associated with drug-dependent DNA-damage, cellular stress and the proteolytic depletion of stem cell factors. In order to further elucidate the mode of action of these nucleoside drugs, we monitored differentiation-specific changes of the dielectric properties of growing NT2 cultures using electric cell-substrate impedance sensing (ECIS). We measured resistance values of untreated and retinoic acid treated NT2 cells in real-time and compared their impedance profiles to those of cell populations triggered to differentiate with several established substances, including nucleoside drugs. Here we show that treatment with retinoic acid and differentiation-inducing drugs can trigger specific, concentration-dependent changes in dielectric resistance of NT2 cultures, which can be observed as early as 24 hours after treatment. Further, low concentrations of nucleoside drugs induce differentiation-dependent impedance values comparable to those obtained after retinoic acid treatment, whereas higher concentrations induce proliferation defects. Finally, we show that impedance profiles of substance-induced NT2 cells and those triggered to differentiate by depletion of the stem cell factor OCT4 are very similar, suggesting that reduction of OCT4 levels has a dominant function for differentiation induced by nucleoside drugs and retinoic acid. The data presented show that NT2 cells have specific dielectric properties, which allow the early identification of differentiating cultures and real-time label-free monitoring of differentiation processes. This work might provide a basis for further analyses of drug candidates for differentiation therapy of cancers.

Oz, Simin; Maercker, Christian; Breiling, Achim

2013-01-01

138

X-ray Reflectivity Study on Depth Profile of Acid Generator Distribution in Chemically Amplified Resists  

NASA Astrophysics Data System (ADS)

In the sub-100-nm mass production of semiconductor devices, thin-film resists dispersing acid generator molecules, referred to as chemically amplified resists, have been used. Feature sizes in lithography are approaching the molecular scale with the rapid progress in miniaturization. With reductions in lateral dimensions, a decrease in resist thickness is inevitable and the effects of interfaces become significant. A requirement for ultrafine fabrication is the uniformity of resist components. In this work, the depth profile of the acid generator distribution was investigated by X-ray reflectivity measurement at SPring-8. The depth profile in thin resist films was clarified. It was found that the depth profile varies with acid generator concentration.

Fukuyama, Takehiro; Kozawa, Takahiro; Tagawa, Seiichi; Takasu, Ryoichi; Yukawa, Hiroto; Sato, Mitsuru; Onodera, Junichi; Hirosawa, Ichiro; Koganesawa, Tomoyuki; Horie, Kazuyuki

2008-06-01

139

Direct-Current Resistivity Profiling at the Pecos River Ecosystem Project Study Site near Mentone, Texas, 2006  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with Texas A&M University AgriLife, did a surface geophysical investigation at the Pecos River Ecosystem Project study site near Mentone in West Texas intended to determine shallow (to about 14 meters below the water [river] surface) subsurface composition (lithology) in and near treated (eradicated of all saltcedar) and control (untreated) riparian zone sites during June-August 2006. Land-based direct-current resistivity profiling was applied in a 240-meter section of the riverbank at the control site, and waterborne direct-current continuous resistivity profiling (CRP) was applied along a 2.279-kilometer reach of the river adjacent to both sites to collect shallow subsurface resistivity data. Inverse modeling was used to obtain a nonunique estimate of the true subsurface resistivity from apparent resistivity calculated from the field measurements. The land-based survey showed that the sub-surface at the control site generally is of relatively low resis-tivity down to about 4 meters below the water surface. Most of the section from about 4 to 10 meters below the water surface is of relatively high resistivity. The waterborne CRP surveys convey essentially the same electrical representation of the lithology at the control site to 10 meters below the water surface; but the CRP surveys show considerably lower resistivity than the land-based survey in the subsection from about 4 to 10 meters below the water surface. The CRP surveys along the 2.279-kilometer reach of the river adjacent to both the treated and control sites show the same relatively low resistivity zone from the riverbed to about 4 meters below the water surface evident at the control site. A slightly higher resistivity zone is observed from about 4 to 14 meters below the water surface along the upstream approximately one-half of the profile than along the downstream one-half. The variations in resistivity could not be matched to variations in lithology because sufficient rock samples were not available.

Teeple, Andrew P.; McDonald, Alyson K.; Payne, Jason D.; Kress, Wade H.

2009-01-01

140

Antimicrobial resistance profile of Actinobacillus pleuropneumoniae and Actinobacillus porcitonsillarum.  

PubMed

A total of 83 Actinobacillus pleuropneumoniae and 58 Actinobacillus porcitonsillarum strains collected from slaughtered pigs in Switzerland were screened for susceptibility to 20 antimicrobial agents by MIC determinations. Resistance to sulfamethoxazole, the combination sulfamethoxazole-trimethoprim, tiamulin, tilmicosin, tetracycline, penicillin and ampicillin were found. A few A. porcitonsillarum isolates displayed decreased susceptibility to enrofloxacin. PCR analysis revealed the presence of the sul2 gene in approximately one-fifth of the sulfonamide-resistant A. pleuropneumoniae and A. porcitonsillarum isolates. The tetracycline-resistant A. pleuropneumoniae harbored tet(B) and tet(H), whereas the tetracycline-resistant A. porcitonsillarum isolates harbored the tet(B) gene. The penicillin and ampicillin-resistant A. pleuropneumoniae and A. porcitonsillarum harbored the bla(ROB-1) gene. PMID:17314014

Matter, Denise; Rossano, Alexandra; Limat, Sandra; Vorlet-Fawer, Lorianne; Brodard, Isabelle; Perreten, Vincent

2007-01-19

141

Study concerning the electrical resistivity of some liquid metals in ultrasonic field  

Microsoft Academic Search

The increasing of the electrical resistivity values for the overheated high-purity liquid aluminium in range 934 K to 1043 K and for aluminium-silicon eutectic alloy in range 850 K to 960 K, during high-energy ultrasonic field presence is reported. We used DC electrical resistivity measurements. The modification of electrical resistivity values in ultrasonic field due to electron-ion interaction processes and

Luminita Moraru

1999-01-01

142

The effects of rotation, electric field, and recycling neutrals on determining the edge pedestal density profile  

SciTech Connect

The edge density profile is calculated from the continuity and momentum balance equations, using experimental electric field and rotation velocities and a calculated recycling neutral source, to evaluate the relative importance of these quantities in determining the observed structure of the edge density profile in a DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] high-confinement mode discharge.

Stacey, W. M. [Fusion Research Center, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2010-05-15

143

The Static Electricity Resistant Liquid Crystal Display Driven by Fringe Electric Field  

NASA Astrophysics Data System (ADS)

In this paper, we propose the static electricity resistant liquid crystal display (LCD) driven by fringe electric field. In the device, the conductive Cr metal playing role as black matrix (BM) in the top glass substrate is connected to the common electrode on the bottom substrate by the Ag transfer dotting. In addition, the common electrode also contacts to border chassis, allowing it to serve as the path for discharging the static charge generated on the top glass surface when peeling off the protective layer of the polarizer. Therefore, the electrostatic charges near BM or in the active region move fast enough to the CrBM for neutralization, while keeping the display in the neutral state electrically. The proposed LCD utilizes a liquid crystal mixture with negative dielectric anisotropy, allowing the device to be in much stable state against noise field generated by CrBM or external electrostatic discharge (ESD). We expect that this proposed structure is suitable to electrostatic resistant fringe-field switching (FFS)-LCD with a high image quality.

Kim, Mi Sook; Seen, Seung Min; Lee, Seung Hee

2012-04-01

144

Low-thermal-resistance, high-electrical-isolation heat intercept connection.  

National Technical Information Service (NTIS)

A method for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection is presented. Electrical conductors often require the removal of heat produced from their normal operation. The heat can be removed by mechanical connecti...

R. C. Niemann J. D. Gonczy T. H. Nicol

1993-01-01

145

Electrical resistivity measurement - A technique to monitor damage progression in CFRP-laminates  

NASA Astrophysics Data System (ADS)

Electrical resistivity due to fiber loading is determined on a screw-driven tensile test machine, fatigue tests are performed on a servohydrolic test machine, and the specimen temperatures are measured with a thermocouple. Variations in electrical resistivity during static loadings is interpreted as a clear indication of fibre fracture. It is also observed that electrical resistivity increases just from the beginning of the fatigue test, but it decreases in the course of further fatigue loadings. Near the end of the fatigue life, electrical resistivity increases again, while stiffness decreases. It is concluded that this method can be used as a nondestructive evacuation technique for CFRP parts.

Schulte, K.; Baron, Ch.

146

Gene expression profiling of Naïve sheep genetically resistant and susceptible to gastrointestinal nematodes  

Microsoft Academic Search

BACKGROUND: Gastrointestinal nematodes constitute a major cause of morbidity and mortality in grazing ruminants. Individual animals or breeds, however, are known to differ in their resistance to infection. Gene expression profiling allows us to examine large numbers of transcripts simultaneously in order to identify those transcripts that contribute to an animal's susceptibility or resistance. RESULTS: With the goal of identifying

Orla M Keane; Amonida Zadissa; Theresa Wilson; Dianne L Hyndman; Gordon J Greer; David B Baird; Alan F McCulloch; Allan M Crawford; John C McEwan

2006-01-01

147

Electrical resistivity tomography at the DOE Hanford site  

SciTech Connect

Recent work at the DOE Hanford site has established the potential of applying Electrical Resistivity Tomography (ERT) for early leak detection under hazardous waste storage facilities. Several studies have been concluded to test the capabilities and limitations of ERT for two different applications. First, field experiments have been conducted to determine the utility of ERT to detect and map leaks from underground storage tanks during waste removal processes. Second, the use of ERT for long term vadose zone monitoring has been tested under different field conditions of depth, installation design, acquisition mode/equipment and infiltration chemistry. This work involves transferring the technology from Lawrence Livermore National Laboratory (LLNL) to the Resource Conservation and Recovery Act (RCRA) program at the DOE Hanford Site. This paper covers field training studies relevant to the second application for long term vadose zone monitoring.

Narbutovskih, S.M.; Halter, T.D.; Sweeney, M.D. [Westinghouse Hanford Co., Richland, WA (United States); Daily, W.; Ramirez, A.L. [Lawrence Livermore National Lab., CA (United States)

1996-01-01

148

Electric vehicle drivetrain: Sizing and validation using general and particular mission profiles  

Microsoft Academic Search

This paper presents the validation of the new European mission profiles on an electric vehicle simulator developed in the environment of AMESim (Advanced Modelin g Environment for simulation). The electric vehicle drivetrain components are sized according to defined specifications and vehicle characteristics. A simplified control strategy is proposed in order to minimize the battery consumption. Taking into account the vehicle

Rabia Sehab; B. Barbedette; M. Chauvin

2011-01-01

149

Low-thermal-resistance, high-electrical-isolation heat intercept connection  

SciTech Connect

A method for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection is presented. Electrical conductors often require the removal of heat produced from their normal operation. The heat can be removed by mechanical connection to a refrigeration source. Such connections require both effective heat removal (low thermal resistance) and effective electrical isolation (high electrical resistance and high dielectric strength). Such connections should be straightforward to fabricate and provide reliable performance that is independent of operating temperature. The connection method described here involves clamping, by thermal interference fit, an electrically insulating cylinder between an outer metallic ring and an inner metallic disk.

Niemann, R.C.; Gonczy, J.D. (Argonne National Lab., IL (United States)); Nicol, T.H. (Fermi National Accelerator Lab., Batavia, IL (United States))

1993-01-01

150

Water storage mapping of pyroclastic covers through electrical resistivity measurements  

NASA Astrophysics Data System (ADS)

The knowledge of the geological setting of pyroclastic covers and their water content distribution represents crucial information for stability analyses of slopes potentially subject to debris-flow phenomena. The study we here present would provide a contribution to this issue by means of an approach based on electrical resistivity measurements. Specifically, we describe the results of high-resolution 2D resistivity surveys carried out in a test area on Sarno Mountains (Campania Region - Southern Italy), where shallow landslides involving pyroclastic soils periodically occur triggered by critical rainfall events. We discuss the results in relation to the geology of the area in order to locate characteristic horizons of pyroclastic soils below the ground surface. Then, on the basis of a laboratory characterization of pyroclastic samples collected from the same test area at representative depths, we provide an estimation of the soil water content distribution in the field. Finally, we analyze temporal variations of the soil water content distribution by comparing the data of two surveys carried out in the autumnal and spring seasons, respectively.

di Maio, R.; Piegari, E.

2011-10-01

151

Monitoring Permeable Reactive Barriers using Electrical Resistance Tomography  

SciTech Connect

An electrical resistivity tomography (ERT) method is being evaluated as a measurement tool to determine the integrity of permeable reactive barriers (PRBs) during and after construction of the barrier and as a monitoring tool to determine the long-term operational health of the barrier. The method is novel because it inserts the electrodes directly into the barrier itself. Numerical modeling calculations indicate that the ERT method can detect flaws (voids) in the barrier as small as 0.11 m{sup 2} (0.33 m x 0.33 m) when the aspect ratio of the electrodes are 2:1. Laboratory measurements indicate that the change in resistance over time of the iron-filling mixture used to create the PRB is sufficient for ERT to monitor the long-term health of the barrier. The use of this ERT method allows for the cost-effective installation of the barrier, especially when the vadose zone is large, because borehole installation methods, rather than trenching methods, can be used.

Ramirez, A; Bratton, W; Maresca, J; Daily, W; Dickerson, W

2003-12-08

152

The effect of electrical conductivity on pore resistance and electroporation  

NASA Astrophysics Data System (ADS)

Electroporation is an elegant means to gain access to the cytoplasm, and to deliver molecules into the cell while simultaneously maintaining viability and functionality. In this technique, an applied electric pulse transiently permeabilizes the cell membrane, through which biologically active agents such as DNA, RNA, and amino acids can enter the cell, and perform tasks such as gene and cancer therapy. Despite wide applications, current electroporation technologies fall short of desired efficiency and reliability, in part due to the lack of fundamental understanding and quantitative modeling tools. This work focuses on the modeling of cell membrane conductance due to the formation of aqueous conducting pores. An analytical expression is developed to determine effective pore resistance as a function of the membrane thickness, pore size, and intracellular and extracellular conductivities. The availability of this expression avoids empirical or ad hoc specification of the conductivity of the pore-filling solution which was adopted in previous works. Such pore resistance model is then incorporated into a whole-cell electroporation simulation to investigate the effect of conductivity ratio on membrane permeabilization. The results reveal that the degree of permeabilization strongly depends on the specific values of the extracellular and intracellular conductivities.

Li, Jianbo; Lin, Hao

2008-11-01

153

Advances in the application of in situ electrical resistance heating  

SciTech Connect

Electrical Resistance Heating (ERH) is an aggressive in situ thermal remediation technology that was developed by the U.S. Department of Energy from the original oil production technology to enhance vapor extraction remediation technologies in low permeability soils. Soil and groundwater are heated by the passage of electrical current through saturated and unsaturated soil between electrodes, not by the electrodes themselves. It is the resistance to the flow of electrical current that results in increased subsurface temperatures, and this is typically applied to the boiling point of water. It is estimated that more than 75 ERH applications have been performed. Capacity to perform these projects has increased over the years, and as many as 15 to 20 of these applications now being performed at any given time, mainly in North America, with some European applications. While the main focus has been to vaporize volatile organic compounds, as one would expect other semi-volatile and non-volatile organic compounds have also been encountered, resulting in observations of chemical and physical reactions that have not been normally incorporated into environmental restoration projects. One such reaction is hydrolysis, which is slow under normal groundwater temperatures, becomes very rapid under temperatures that can easily be achieved using ERH. As a result, these chemical and physical reactions are increasing the applicability of ERH in environmental restoration projects, treating a wider variety of compounds and utilizing biotic and abiotic mechanisms to reduce energy costs. For the treatment of oil and coal tar residues from manufactured gas plants, a process TRS has called steam bubble floatation is used to physically remove the coal and oil tar from the soils for collection using conventional multi-phase collection methods. Heat-enhanced hydrolysis has been used to remediate dichloromethane from soils and groundwater at a site in Illinois, while heat-enhanced biotic and abiotic dehalogenation has been observed at the vast majority of the sites where ERH has been applied. With disposal options becoming more limited around the world, alternate in situ treatment methods for soil and groundwater restoration are becoming more important. Over the 10 years of commercialization of the ERH technology, soil and groundwater remediation mechanisms and processes that were not envisioned by the technology's developers expand the range of chemicals that have successfully been treated. This paper will discuss these processes and how these processes have been used to effect remediation of soil and groundwater where ERH has been employed. (authors)

Smith, Gregory J. [Thermal Remediation Services, Woodridge, IL (United States); Beyke, Gregory [Thermal Remediation Services, Franklin, TN (United States)

2007-07-01

154

The Use of Cone-Based Electrical Resistivity Tomography to Image Conductive Contaminants.  

NASA Astrophysics Data System (ADS)

Determining the 3D spatial distribution of subsurface contaminants is a challenging task. Most methods sample small regions immediately adjacent to wells or testing devices, thus providing data which are not representative of the entire region of interest. Furthermore, at many sensitive sites invasive methods that are usually employed to characterize contaminants are no longer acceptable, as the risk for exposing workers and spreading contaminants is too high. By integrating geophysical resistivity imaging with cone-penetration testing, we are developing a technology that addresses both of these issues by being minimally invasive while providing information about the 3D distribution of electrically conductive subsurface contamination. This new technique, cone-based electrical resistivity tomography (C-bert), involves placing several permanent current electrodes in the subsurface and using electrodes mounted on the cone-penetrometer to measure the resultant potential field while advancing the cone into the sub-surface. In addition to potential field measurements, we obtain the standard suite of cone-penetration measurements, including high resolution resistivity logs; these data can then be used to constrain the inversion of the potential field data. We recently performed a C-bert experiment to image a salt water intrusion in a fresh water aquifer in Vancouver, British Columbia. A total of nine current electrodes were emplaced at the site and five C-bert profiles were obtained, resulting in approximately 8000 independent data points. Obtaining data at the site proved challenging because of current channeling through the low resistivity salt-water wedge; for certain electrode configurations, this channeling pressed the power limitations of our resistivity unit, resulting in noisy data. In addition, the variation of in-situ resistivity over several orders of magnitude requires specific care be taken with data weighting and model regularization during inversion. To test ways to reduce computational time, we did not explicitly include the effect of the conductive cone in the initial inversion of the data. The inversion results that we obtained, along with forward modeling of the conductive cone, suggest that, for the resistivity structure and measurement geometry at the site, the effect of the cone can be considered second order. We conclude, from this first field test, that this method is a promising new way to image the subsurface.

Pidlisecky, A.; Knight, R.

2004-05-01

155

Electrical Resistance Tomography Field Trials to Image CO2 Sequestration  

NASA Astrophysics Data System (ADS)

If geologic formations are used to sequester or store carbon dioxide (CO2) for long periods of time, it will be necessary to verify the containment of injected CO2 by assessing leaks and flow paths, and by understanding the geophysical and geochemical interactions between the CO2 and the geologic minerals and fluids. Remote monitoring methods are preferred, to minimize cost and impact to the integrity of the disposal reservoir. Electrical methods are especially well suited for monitoring processes involving fluids, as electrical properties are most sensitive to the presence and nature of the fluids contained in the medium. High resolution tomographs of electrical properties have been used with success for site characterization, monitoring subsurface migration of fluids in instances of leaking underground tanks, water infiltration events, subsurface steam floods, contaminant movement, and assessing the integrity of subsurface barriers. These surveys are commonly conducted utilizing vertical arrays of point electrodes in a crosswell configuration. Alternative ways of monitoring the reservoir are desirable due to the high costs of drilling the required monitoring boreholes Recent field results obtained using steel well casings as long electrodes are also promising. We have conducted field trials to evaluate the effectiveness of long electrode ERT as a potential monitoring approach for CO2 sequestration. In these trials, CO2 is not being sequestered but rather is being used as a solvent for enhanced oil recovery. This setting offers the same conditions expected during sequestration so monitoring secondary oil recovery allows a test of the method under realistic physical conditions and operational constraints. Field experience has confirmed the challenges identified during model studies. The principal difficulty are the very small signals due to the fact that formation changes occur only over a small segment of the 5000 foot length of the electrodes. In addition, telluric noise can be comparable to the signal levels during periods of geomagnetic activity. Finally, instrumentation stability over long periods is necessary to follow trends in reservoir behavior for several years. Solutions to these and other problems will be presented along with results from the first two years of work at a producing field undergoing CO2 flood. If electrical resistance tomography (ERT) imaging can be performed using existing well casings as long electrodes, it will substantially reduce the cost to monitor CO2 sequestration. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Newmark, R.

2003-12-01

156

Characterization of endemic Shigella flexneri strains in Somalia: antimicrobial resistance, plasmid profiles, and serotype correlation.  

PubMed Central

One hundred twelve Shigella flexneri strain isolated from children with diarrheal disease in Somalia in 1983, 1984, 1988, and 1989 were analyzed for serotype, plasmid profile, and genetic location of antimicrobial resistance determinants. The prevalent serotypes were 4 (46% of the isolates), 1b (16%), 2a (16%), 3a (12%), and 6 (8%). Each serotype was associated with a characteristic predominant plasmid profile, whereas no specific correlation between antimicrobial resistance patterns and single serotypes was found. All but three of the strains were resistant at least to ampicillin, chloramphenicol, spectinomycin, and tetracycline. Of these resistant strains, 41 were resistant to sulfonamide and streptomycin and 14 were resistant to trimethoprim or trimethoprim and kanamycin. The genes for resistance to ampicillin, chloramphenicol, spectinomycin, and tetracycline formed a linkage group located on the chromosome of the strains of all serotypes. The genes for resistance to sulfonamide and streptomycin were located on a 6.3-kb plasmid in strains of serotypes 1b, 2a, and 4. Conjugative trimethoprim or trimethoprim and kanamycin resistance plasmids with lengths of 80 to 110 kb were present in strains of serotypes 1b, 2a, 3a, and 4. The systematic presence of a chromosomal component in this uncommon genetic plasmid-chromosome configuration may play a role in the emergence of increased genetic stability of resistance patterns in S. flexneri. Images

Casalino, M; Nicoletti, M; Salvia, A; Colonna, B; Pazzani, C; Calconi, A; Mohamud, K A; Maimone, F

1994-01-01

157

Role of functional groups on the microwave attenuation and electric resistivity of activated carbon fiber cloth  

Microsoft Academic Search

Virgin activated carbon fiber cloth (ACFC) samples with select degrees of activation\\/porosity were treated with nitric and sulfuric acids or with hydrogen. Composition, microwave attenuation constant and electric resistivity results for these samples are provided. On average, acid treatment resulted in a 677% increase in oxygen content, 89% decrease in microwave attenuation constant, and 3200% increase in electrical resistivity when

Zaher Hashisho; Mark J. Rood; Suhail Barot; Jennifer Bernhard

2009-01-01

158

Study of critical dependence of stable phases in Nitinol on heat treatment using electrical resistivity probe  

Microsoft Academic Search

Phase transformations in 40% cold-worked Nitinol as a function of heat treatment have been studied using electrical resistivity variation with temperature. The stabilisation of austenitic, rhombohedral and martensitic phases is shown to critically depend on the temperatures of heat treatment by the analysis of temperature dependence of electrical resistivity in heating and cooling parts of the cycle. Characteristic values of

J Uchil; K. P Mohanchandra; K. Ganesh Kumara; K. K Mahesh

1998-01-01

159

Estimation of the junctional resistance between electrically coupled receptor cells in Necturus taste buds  

Microsoft Academic Search

Junctional resistance between coupled receptor cells in Necturus taste buds was estimated by modeling the results from single patch pipette voltage clamp studies on lingual slices. The membrane capacitance and input resistance of coupled taste receptor cells were measured to monitor electrical coupling and the results compared with those calculated by a simple model of electrically cou- pled taste cells.

ALBERTINO BIGIANI; STEPHEN D. ROPER

1995-01-01

160

Axial graded silicon carbide fibers with fluctuating carbon layer and sinusoidal electrical resistivity  

Microsoft Academic Search

Axial graded silicon carbide fibers with fluctuating carbon layer and sinusoidal electrical resistivity in the range of 100–102?·cm were prepared. The preparation of these axial graded fibers was simply realized by continuous pyrolysis using an elliptic rotating spool that makes the pyrolysis time of every axial part of the fiber in furnace varies periodically. The period of the electrical resistivity

Tian-jiao Hu; Xiao-dong Li; Yi-he Li; Hao Wang; Jun Wang

2011-01-01

161

Long-Term Monitoring of Infiltration at a Managed Aquifer Recharge Site Using Electrical Resistivity Probes  

Microsoft Academic Search

As part of an effort to understand the hydrogeologic parameters that influence the performance of a managed aquifer recharge project, four Electrical Resistivity Imaging (ERI) probes were installed beneath an artificial recharge pond to monitor changes in bulk electrical resistivity as a function of time. The probes were three meters long and installed to a depth of two meters below

R. Cockett; A. Pidlisecky; R. J. Knight

2010-01-01

162

30 CFR 7.407 - Test for flame resistance of electric cables and cable splices.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Test for flame resistance of electric cables and...Cable Splice Kits § 7.407 Test for flame resistance of electric cables and...this level for the duration of the flame test. The two outermost rods...

2009-07-01

163

30 CFR 7.407 - Test for flame resistance of electric cables and cable splices.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Test for flame resistance of electric cables and...Cable Splice Kits § 7.407 Test for flame resistance of electric cables and...this level for the duration of the flame test. The two outermost rods...

2010-07-01

164

Droplets profiles and wetting transitions in electric fields  

NASA Astrophysics Data System (ADS)

This paper presents current work in electrowetting. In the first part, we discuss experimental measurements of curvature of a conductive liquid drop in an electrical field. A recent theoretical and numerical study [8] predicts that diverging electric fields give rise to deviations close to the contact line from the usual spherical cap shape. We present here the first experimental measurements, compared to numerical simulations. In the second part, we recall how electrowetting is likely to induce wetting transitions, and describe the experimental setup designed to this purpose. Ellipsometry monitoring of film thickness is intended to follow total towards pseudo-partial wetting transition, allowing to reconstruct the effective interface potential of the system, acting like the electrostatic counterpart to the mechanical Surface Force Apparatus.

Bienia, Marguerite; Mugele, Frieder; Quilliet, Catherine; Ballet, Patrice

2004-08-01

165

CORRIGENDUM: Multiscale electrical contact resistance in clustered contact distribution Multiscale electrical contact resistance in clustered contact distribution  

NASA Astrophysics Data System (ADS)

The authors wish to explain the similarity between some figures in the above paper (hereafter called the JPD paper) and in their other publication, Lee S, Jang Y H and Kim W 2008 Effects of nanosized contact spots on thermal contact resistance J. Appl. Phys.103 074308 (hereafter called the JAP paper), and to explain the differences between the two papers, which are not explicitly stated in the JPD paper. The main objective of the JAP paper is to calculate the thermal contact resistance of the nanosized contact spots in multiscale contact. During the process of multiscale analysis, the thermal conductivity varies, especially below the phonon mean free path. The JPD paper deals with the electrical contact resistance in the multiscale contact distribution with an assumption of constant electrical resistivity, which is known as a different kind of physics in a larger characteristic length scale. There are similar figures in the JPD paper and the JAP paper: figures 6, 7 and 8 in the JPD paper and figures 3, 4 and 5 in the JAP paper. Two research works were performed on the basis of a specific microcontact distribution. In the JAP paper, the scale of the contact distribution is in the range of the phonon mean free path of Si, which is a very small size of contact distribution. In the JPD paper, the scale of contact distribution is in the continuum scale, which is larger than the phonon mean free path. In addition, due to the characteristics of a fractal surface which repeatedly generates a similar shape of contact distribution in the different length scales, the shape of contact distribution looks similar, but the total sizes of domain in the JPD and JAP figures are different. The projected areas L × L of fractal surface of the JAP paper and JPD paper are 10 ?m × 10 ?m and 10 mm × 10 mm, respectively. The length scale is already stated in the JAP paper, but not in the JPD paper. Thus, we have to state that the figures were adapted from the JAP paper without clear attribution and that credit should be given to the original source of the images. Most significantly, the two most important features of the two works are based on totally different physics and the calculation methods for contact resistance. The text of section 4.3 of the JPD paper should be modified. The left column of page 5 and the first two lines of the right column should be replaced by the following text. The projected area of a self-affine fractal surface is plotted in figure 6. In order to find the microcontact spot distribution from the fractal surface, numerical simulations are applied to the model of multiscale rough surface. Several contact models are constructed according to the resolution of 1/24 to 1/28. Figure 7 shows a typical finite element model in which the rough elastic surface is in contact with a perfectly flat rigid surface. Due to the fine meshes in the contact interface, strong mesh gradations are required. The contact simulation enforcing the impenetrability constraint on the mating surfaces is performed by a commercial finite element package, Abaqus/HKS ([22] of the JPD paper). The resulting microcontact spot distributions for different resolution of the rough surface are obtained in figure 8. As reported by Borri-Brunetto et al ([23] of the JPD paper), the actual contact area decreases and the number of contact spots increases as the resolution of the discretization escalates. A more detailed description for the model can be obtained in the JAP paper.

Lee, Sangyoung; Cho, Hyun; Jang, Yong Hoon

2010-06-01

166

On the Intensity Profile of Electric Lamps and Light Bulbs  

NASA Astrophysics Data System (ADS)

We demonstrate that the time profile of the light intensity from domestic lighting sources exhibits simple yet interesting properties that foster lively student discussions. We monitor the light intensity of an industrial fluorescent lamp (also known as TL) and an incandescent bulb using a photodetector connected to an oscilloscope. The light intensity of these sources displays modulation at twice the ac power supply frequency. The familiarity of ac line power supply, commonplace light sources, and simplicity of the setup encourage student confidence, allowing them to think deeper and continually reassess their notions, and if managed can lead to a satisfactory explanation of the observations.

Bacalla, Xavier; Salumbides, Edcel John

2013-11-01

167

Marine seismic profiling and shallow marine sand resistivity investigations in Broken Bay, NSW, Australia  

NASA Astrophysics Data System (ADS)

A marine continuous seismic profiling (CSP) study and a resistivity study of vibrocore samples of shallow marine sands were undertaken in Broken Bay, NSW, Australia, to characterise the seabed. The overall aims were to provide an estimate of the sediment thickness using CSP and an estimate of sediment resistivity in the upper 4 m of the seabed at selected sites. This information can provide a simplified geo-electrical model to assess the accuracy of interpreted seabed and bedrock depths obtained independently from AEM data and to assist the calibration of AEM instrumentation for bathymetric surveys. The acoustic impedance contrast between deeper sediments and the anticipated basement sandstone was variable suggesting irregularly layered sediments. These sediments contained very dense (tightly packed) sands, owing to marine regression and transgression of sea level, and variably weathered underlying sandstones. Interpreted bedrock levels vary considerably across the survey area and represent drowned river valleys of the inner continental shelf. A broad deep channel representing a high-energy palaeo-fluvial drainage system in the Hawkesbury River outreaches was identified; it extended to approximately -80 m AHD. Another area revealed a dendritic fluvial pattern extending to approximately -70 m AHD. A moderately narrow palaeovalley extending to -90 m AHD either side of the Palm Beach tombolo was clearly identified. This same feature was also clearly identified from airborne electromagnetic data which, when interpreted, showed very good agreement with seismic depths. Sand samples from 17 sites were obtained from vibrocores with a penetration depth of 4.5m. The laboratory resistivity values, obtained from four-electrode measurements on 64 seawater saturated subsamples ranged from 1.3 to 0.6?m (20°C) 0.92?m average. Inter- and intra-site changes in composition (shell/sand), grain packing, grain size, grain shape, cohesion, and inferred porosity were thought to be responsible for minor variations in resistivity. Archie Equation plots showed some scatter, but the data indicate a cementation factor of ~1.6 and an average formation factor of 4.2 for the suites of sands. These values are consistent with values cited in the literature for similar lithologies.

Vrbancich, Julian; Whiteley, Robert J.; Caffi, Peter; Emerson, Don W.

2011-11-01

168

Electrical Resistivity Tomography of the Karstic Aquifer of Bittit spring (Middle Atlas, Morocco)  

NASA Astrophysics Data System (ADS)

The Tabular Middle Atlas reservoir is one of the most important aquifers in northern Morocco. It is mainly a water table fractured reservoir consisting of Lias limestone and dolomite. The matrix permeability is very low and water flows essentially along open fractures and karsts. The Bittit Spring belongs to this karstic system and constitutes an important aquifer lying at the junction between the tabular reservoir and the Sais basin. Bittit spring, with an average annual discharge of about 1600 l/s, contributes largely to water supply of the big city of Meknes. Groundwater circulation is complex due to tectonics and to presence of karstic Quaternary travertine overlying Lias carbonate. In Bittit area, travertine is mostly covered by Quaternary basalt. Up to now water flow paths and the underground karst organization remain misknown, and turbidity affects the water quality after rain events. To highlight these issues, an integrated geophysical survey was performed in this area in the framework of a French-Moroccan scientific project. The geophysical imaging was carried out mainly by Electrical Resistivity Tomography (ERT). Resistivity data were acquired by an ABEM Terrameter SAS1000 and a multi-electrode Lund system imaging using a Wenner array configuration of 64 electrodes and 5m spacing, reaching a depth of about 50m. Topographic corrections and 2D inversion models were performed using Res2Dinv software package. Seven 2D resistivity high resolution images have been obtained allowing to detect, delineate important fractures and also to hydrogeological characterization of the underground karst. A borehole of 100m depth was drilled in order to correlate and calibrate geophysical data and proposed models. Two sub-vertical fracture families have been identified with NE-SW and NW-SE directions respectively. These results correlate well with fracture data analysis gathered from remote sensing Spot images at large scale, and from local field fracture scanline surveys. A 3D picture of the fracture system has been drawn showing a mini-graben structure. Geophysical scans and interpreted fractures were displayed with Gocad software leading to geometric construction of aquifer units and to 3D modelling of subsurface architecture. Several horizontal electrical resistivity profiles and electromagnetic VLF profiles were also performed in order to discriminate between dry and favourable hydrological fractures. ERT appears to be an appropriate geophysical method in this issue, especially by improving understanding of fracture geometry. This study initiates a hydrogeophysical research in the Middle Atlas karst in order to improve water resources management and reducing aquifer vulnerability in the region.

Qarqori, Kh.; Rouai, M.; Moreau, F.; Saracco, G.; Hermitte, D.; Boualoul, M.; Dauteuil, O.; Biessy, G.; Sahbi, H.

2009-04-01

169

DUV resist profile improvement on TiN-deposited metal layer  

NASA Astrophysics Data System (ADS)

Over the past several years, there have been many publications concerning the sensitivity of chemically amplified (CA) resist to substrate contamination. Resist footing phenomena are found on SiN, BPSG, TiN...etc stack films. Many approaches, such as varying the film thickness, oxide deposition, etc., have been proposed to solve this problem, with the sacrifice of increasing process complexity. In this study, we tried to improve DUV photoresist profile on TiN/AlSiCu/BPSG stacked layers. A positive tone CA resist was used and the improvement was carried out through both thin-film and lithography treatments. Since many process parameters were optimized, Taguchi design-of-experiment method was utilized to save processing cost, time and effort. The results turned out that passivation of TiN with hydrogen can improve resist footing better than either oxygen passivation or no treatment. However, the improvement was less significant than lithography process parameters. It is believed that since HMDS serves as an interlayer between TiN substrate and DUV resist, optimizing dehydration hot baking, post baking and post-exposure baking processes apparently has a more direct and significant impact on resist profile improvement than thin-film treatments. It is suggested that in this specific problem, the optimization of lithographic parameters can result in satisfactory resist profile.

Lin, Chia-Hui; Chen, Chun-Cho; Jenq, Jhy-Sayang; Op de Beeck, Maaike; van den Hove, Luc

1996-06-01

170

DEVELOPMENT OF A DEVICE FOR RAPIDLY MEASURING COTTON LINT ELECTRICAL RESISTANCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The moisture content of cotton lint can be predicted from measurements of electrical resistance. New, automated, resistance-type moisture meters for cotton make measurements in less than a second. The sample resistance changes rapidly during the first 10 seconds of the measurement making conclusio...

171

Interpretation of dipole-dipole electrical resistivity survey, Colado geothermal area, Pershing County, Nevada  

Microsoft Academic Search

An electrical resistivity survey in the Colado geothermal area, Pershing County, Nevada has defined areas of low resistivity on each of five lines surveyed. Some of these areas appear to be fault controlled. Thermal fluids encountered in several drill holes support the assumption that the hot fluids may be associated with areas of low resistivity. The evidence of faulting as

C. E. Mackelprang

1980-01-01

172

Research on Nonlinear Feature of Electrical Resistance of Acupuncture Points  

PubMed Central

A highly sensitive volt-ampere characteristics detecting system was applied to measure the volt-ampere curves of nine acupuncture points, LU9, HT7, LI4, PC6, ST36, SP6, KI3, LR3, and SP3, and corresponding nonacupuncture points bilaterally from 42 healthy volunteers. Electric currents intensity was increased from 0??A to 20??A and then returned to 0??A again. The results showed that the volt-ampere curves of acupuncture points had nonlinear property and magnetic hysteresis-like feature. On all acupuncture point spots, the volt-ampere areas of the increasing phase were significantly larger than that of the decreasing phase (P < 0.01). The volt-ampere areas of ten acupuncture point spots were significantly smaller than those of the corresponding nonacupuncture point spots when intensity was increase (P < 0.05 ~ P < 0.001). And when intensity was decrease, eleven acupuncture point spots showed the same property as above (P < 0.05 ~ P < 0.001), while two acupuncture point spots showed opposite phenomenon in which the areas of two acupuncture point spots were larger than those of the corresponding nonacupuncture point spots (P < 0.05 ~ P < 0.01). These results show that the phenomenon of low skin resistance does not exist to all acupuncture points.

Wei, Jianzi; Mao, Huijuan; Zhou, Yu; Wang, Lina; Liu, Sheng; Shen, Xueyong

2012-01-01

173

Electrical resistance tomography using steel cased boreholes as electrodes  

SciTech Connect

Electrical resistance tomography (ERT) using multiple electrodes installed in boreholes has been shown to be useful for both site characterization and process monitoring. In some cases, however, installing multiple downhole electrodes is too costly (e.g., deep targets) or risky (e.g., contaminated sites). For these cases we have examined the possibility of using the steel casings of existing boreholes as electrodes. The first case we investigated used an array of steel casings as electrodes. This results in very few data and thus requires additional constraints to limit the domain of possible inverse solutions. Simulations indicate that the spatial resolution and sensitivity are understandably low but it is possible to coarsely map the lateral extent of subsurface processes such as steam floods. A hybrid case uses traditional point electrode arrays combined with long-conductor electrodes (steel casings). Although this arrangement provides more data, in many cases it results in poor reconstructions of test targets. Results indicate that this method may hold promise for low resolution imaging where steel casings can be used as electrodes.

Newmark, R L; Daily, W; Ramirez, A

1999-03-22

174

Electrical resistance tomography using steel cased boreholes as long electrodes  

SciTech Connect

Electrical resistance tomography (ERT) using multiple electrodes installed in boreholes has been shown to be useful for both site characterization and process monitoring. In some cases, however, installing multiple downhole electrodes is too costly (e.g., deep targets) or risky (e.g., contaminated sites). For these cases we have examined the possibility of using the steel casings of existing boreholes as electrodes. Several possibilities can be considered. The first case we investigated uses an array of steel casings as electrodes. This results in very few data and thus requires additional constraints to limit the domain of possible inverse solutions. Simulations indicate that the spatial resolution and sensitivity are understandably low but it is possible to coarsely map the lateral extent of subsurface processes such as steam floods. The second case uses an array of traditional point borehole electrodes combined with long-conductor electrodes (steel casings). Although this arrangement provides more data, in many cases it results in poor reconstructions of test targets. Results indicate that this method may hold promise for low resolution imaging where steel casings can be used as electrodes but the merits depend strongly on details of each application. Field tests using these configurations are currently being conducted.

Daily, W; Newmark, R L; Ramirez, A

1999-07-20

175

High electric resistant zirconia and/or hafnia ceramics  

SciTech Connect

Disclosed are Zirconia and/or hafnia-containing ceramics having high electric resistivity and mechanical strength which consists essentially of 5-30 mol % of at least one component of Group A consisting of YO, ScO, SmO, EuO, GdO, TbO, DyO, HoO, ErO, TmO, YbO, LuO, CaO and MgO, 5-40 mol % of at least one component of Group B consisting of NbO and TaO and 30-90 mol % of at least one component of Group C consisting of ZrO/sub 2/ and HfO/sub 2/, said ceramics preferably satisfying the following equation ..sigma..((4-(ion valence number of each component of Group A))X(number of mole of each component of Group A))less than or equal to(total number of mole of components of Group B). and crystal phase of said ceramics being preferred to be composed mainly of tetragonal phase.

Mase, S.; Soejima, S.

1985-03-26

176

Three-dimensional electrical resistivity model of a nuclear waste disposal site  

SciTech Connect

A three-dimensional (3D) modeling study was completed on a very large electrical resistivity survey conducted at a nuclear waste site in eastern Washington. The acquisition included 47 pole-pole two dimensional (2D) resistivity profiles collected along parallel and orthogonal lines over an area of 850 m×570 m. The data were geo-referenced and inverted using EarthImager3D (EI3D). EI3D runs on a Microsoft 32-bit operating system (e.g. WIN-2K, XP) with a maximum usable memory of 2 GB. The memory limits the size of the domain for the inversion model to 200 m×200 m, based on the survey electrode density. Therefore, a series of increasing overlapping models were run to evaluate the effectiveness of dividing the survey area into smaller subdomains. The results of the smaller subdomains were compared to the inversion results of a single domain over a larger area using an upgraded form of EI3D that incorporates multi-processing capabilities and 32 GB of RAM memory. The contours from the smaller subdomains showed discontinuity at the boundaries between the adjacent models, which do not match the hydrogeologic expectations given the nature of disposal at the site. At several boundaries, the contours of the low resistivity areas close, leaving the appearance of disconnected plumes or open contours at boundaries are not met with a continuance of the low resistivity plume into the adjacent subdomain. The model results of the single large domain show a continuous monolithic plume within the central and western portion of the site, directly beneath the elongated trenches. It is recommended that where possible, the domain not be subdivided, but instead include as much of the domain as possible given the memory of available computing resources.

Rucker, Dale F.; Levitt, Marc T.; Greenwood, William J.

2009-12-11

177

Resistance pattern and antioxidant enzyme profiles of protoporphyrinogen oxidase (PROTOX) inhibitor-resistant transgenic rice  

Microsoft Academic Search

We quantified the resistance levels of transgenic rice plants, expressing Myxococcus xanthus protoporphyrinogen oxidase (PROTOX) in chloroplasts and mitochondria, to PROTOX inhibitors, acifluorfen, oxyfluorfen, carfentrazone-ethyl, and oxadiazon. We also determined whether active oxygen species-scavenging enzymes are involved in the resistance mechanism of transgenic rice. The transgenic rice line M4 was about >200-fold more resistant to oxyfluorfen than the wild-type (WT).

Ha Il Jung; Yong In Kuk; Kyoungwhan Back; Nilda R. Burgos

2008-01-01

178

Electric field profile in the presence of sawtooth activity in a tokamak  

SciTech Connect

The two coupled diffusive equations for the perturbed electron temperature and poloidal magnetic field have been solved in the framework of the Kadomtsev model for the sawtooth activity. It is found that the time averaged toroidal electric field profile is radially nonuniform. A simple formula that describes the radial behavior of the toroidal electric field is proposed, and the effect on the power balance is presented.

Alladio, F.; Vlad, G.

1988-03-01

179

Electric field effects associated with the backside Ge profile in SiGe HBTs  

Microsoft Academic Search

A comprehensive investigation of electric field effects associated with the backside Ge profile in SiGe heterojunction bipolar transistors (HBTs) is conducted using calibrated simulations. We show for the first time that the backside Ge retrograde can alter the local electric field distribution in the base–collector space-charge region near the SiGe to Si heterojunction, thereby affecting the impact ionization and the

Gang Zhang; John D. Cressler; Lou Lanzerotti; Rob Johnson; Zhenrong Jin; Shiming Zhang; Guofu Niu; Alvin Joseph; David Harame

2002-01-01

180

Velocity profile method for time varying resistance in minimal cardiovascular system models  

NASA Astrophysics Data System (ADS)

This paper investigates the fluid dynamics governing arterial flow used in lumped parameter cardiovascular system (CVS) models, particularly near the heart where arteries are large. Assumptions made in applying equations conventionally used in lumped parameter models are investigated, specifically that of constant resistance to flow. The Womersley number is used to show that the effects of time varying resistance must be modelled in the pulsatile flow through the large arteries near the heart. It is shown that the equation commonly used to include inertial effects in fluid flow calculations is inappropriate for including time varying resistance. A method of incorporating time varying resistance into a lumped parameter model is developed that uses the Navier-Stokes equations to track the velocity profile. Tests on a single-chamber model show a 17.5% difference in cardiac output for a single-chamber ventricle model when comparing constant resistance models with the velocity profile tracking method modelling time varying resistance. This increase in precision can be achieved using 20 nodes with only twice the computational time required. The method offers a fluid dynamically and physiologically accurate method of calculating large Womersley number pulsatile fluid flows in large arteries around the heart and valves. The proposed velocity profile tracking method can be easily incorporated into existing lumped parameter CVS models, improving their clinical application by increasing their accuracy.

Smith, Bram W.; Chase, J. Geoffrey; Nokes, Roger I.; Shaw, Geoffrey M.; David, Tim

2003-10-01

181

Aggregated Impact of Plug-in Hybrid Electric Vehicles on Electricity Demand Profile  

Microsoft Academic Search

Greenhouse gas emissions, air pollution i nu rban areas, and dependence on fossil fuels are among the challenges threatening the sustainable development of the transportation sector. Plug-in hybrid electric vehicle (PHEV) technology is one of the most promising solutions to tackle the situation. While PHEVs partially rely on electricity from the power grid, they raise concerns about their negative impacts

Zahra Darabi; Mehdi Ferdowsi

2011-01-01

182

Contact resistance of micromachined electrical switches incorporating a chevron-type bi-stable spring  

NASA Astrophysics Data System (ADS)

Micromachined electrical switches with bi-stable springs, which can stay at one of the two stable states without consuming energy, are proposed. Cascaded bent beams are incorporated as thermoelastic microactuators and are characterized through a coupled electro-thermo-mechanical analysis using ANSYS. For improved electrical switch performance, the contact resistances should be kept as low as possible. Therefore, the shape of the contact head needs to be optimized, though to date there have been few studies pertaining to the contact heads of electrical switches reported, except for a flat contact shape. In this paper, the effects of contact angle on the electrical resistance are investigated for contact angles of 30°, 45°, and 60°. It is subsequently observed that the contact resistance decreases with the contact angle due to a greater normal contact force; the minimum contact resistance is 0.22 ? at a contact angle of 60°. The contact resistance shows negligible change during repeated ON/OFF switching operations.

Nallamuthu, Punithavelan; Hwang, Il-Han; Jeong, Dae-Hun; Moon, Seung-Hwan; Seo, Seung-Wan; Lee, Jong-Hyun

2011-01-01

183

Electrical resistivity and piezoresistivity of Ni-CNT filled epoxy-based composites  

NASA Astrophysics Data System (ADS)

This paper investigates properties about electrical resistivity and piezoresistivity of multi-wall carbon nanotubes (MWCNTs)-filled epoxy-based composite and its further use for strain sensing. The MWCNTs dispersed epoxy resin, using MWCNTs in the amount of 1.5~3.0 vol.%, was first prepared by combined high-speed stirring and sonication methods. Then, the MWCNTs dispersed epoxy resin was cast into an aluminum mold to form specimens measuring 10×10×36 mm. After curing, DC electrical resistance measurements were performed along the longitudinal axis using the four-probe method, in which copper nets served as electrical contacts. The percolation threshold zone of resistivity was got as MWCNTs in the amount of 2.00-2.50 vol.%. Further compressive testing of these specimens was conducted with four-probe method for resistance measurements at the same time. Testing results show that the electrical resistivity of the composites changes with the strain's development, namely piezoresistivity. While for practical strain sensing use, signals of electric resistance and current in the acquisition circuits were both studied. Results show that the signal of current, compared with that of resistance, had better linear relationship with the compressive strain, better stability and longer effective section to reflect the whole deformation process of the specimens under pressure. Further works about the effects of low magnetic field on the electrical resistivity and piezoresistivity of Ni-CNTs filled epoxy-based composites were presented briefly at the end of the paper.

Jiang, Jinbao; Xiao, Huigang; Li, Hui

2013-04-01

184

Electrical resistivity imaging for characterizing dynamic hydrologic systems  

NASA Astrophysics Data System (ADS)

Electrical resistivity imaging (ERI) is widely used in hydrogeophysical studies for monitoring spatiotemporal variations in hydrologic properties and processes. Its applications to hydrologic settings found in sandy and other coarse-grained soils have been demonstrated. However, there has been limited use of the method for characterization of dynamic hydrologic systems such as those found in Vertisols (typical heavy-clay soils) and water layers in lakes. One reason for this is that principles that work well in sandy and loamy soils often produce erroneous results in clay soils. In addition, because of the dynamic nature of such systems, detailed empirical and computational studies are required to fully understand various properties, which vary spatially within a few meters or less, and temporally in less than few days. This dissertation investigates the effectiveness of ERI for characterizing dynamic hydrologic systems. Two specific questions are addressed: (1) Can spatiotemporal hydrologic variations in such systems be effectively characterized using ERI? (2) How accurately can the true resistivity distribution in the systems be determined? To address the first question, geoelectric studies of seasonal wetting and drying of a Texas Vertisol were carried out. Data processing involved inversion, temperature corrections and time-lapse analysis. In addition, a van Genuchten water retention function was incorporated into the study to estimate moisture flux. To answer the second question, theoretical and field geoelectric data from Lake Whitney, Texas, USA, were analyzed. Following an introduction to the research in chapter one, results of geoelectric studies of seasonal wetting and drying of the Texas Vertisol are presented in chapter two. Results reveal the seasonal hydrodynamics of the soil as they are controlled by micro-relief topography (gilgai) and cracks. In chapter three, time-lapse analysis and computations of the apparent moisture flux are discussed. This study shows that integrative hydrogeophysical and hydropedological method is a viable approach for visualizing moisture flux in soils. In chapter four, results of geoelectric studies in Lake Whitney are discussed with recommendations for advancing the ERI as a tool in limnological research for mapping freshwater zones within impacted lakes and water reservoirs. Chapter five presents brief summary and conclusion of the research.

Amidu, Sikiru Adetona

185

Corrosion-resistant, electrically-conductive plate for use in a fuel cell stack  

DOEpatents

A corrosion resistant, electrically-conductive, durable plate at least partially coated with an anchor coating and a corrosion resistant coating. The corrosion resistant coating made of at least a polymer and a plurality of corrosion resistant particles each having a surface area between about 1-20 m.sup.2/g and a diameter less than about 10 microns. Preferably, the plate is used as a bipolar plate in a proton exchange membrane (PEMFC) fuel cell stack.

Carter, J. David (Bolingbrook, IL); Mawdsley, Jennifer R. (Woodridge, IL); Niyogi, Suhas (Woodridge, IL); Wang, Xiaoping (Naperville, IL); Cruse, Terry (Lisle, IL); Santos, Lilia (Lombard, IL)

2010-04-20

186

Method for the formation of cylindrical current and its application to evaluate electrical resistivity  

NASA Astrophysics Data System (ADS)

A cylindrical current method is developed to obtain a stable and precise electrical resistivity of a specimen with or without a coating film. The electrical resistivity of a standard silicon wafer doped with boron at a concentration can be measured using the proposed method if the experimental results of electrical voltage varying with the distance from the center line of the cylindrical current are available. A comparison of the electrical resistivity obtained using the present method and the theoretical reference value indicates that the proposed method produces reliable and precise measurements. Using four test samples, the experimental results of electrical resistivity measured by the present method are shown to be reproducible and more precise than those measured by the four-terminal sensing method and the van der Pauw method. The electrical voltage and current obtained at various distances from the center line of the cylindrical current are almost independent of the distance and the direction of measurements. The effect of specimen's crystallinity appears to be the governing factor of electrical resistivity. Electrical resistivity decreases with increasing crystallinity generally.

Li, T.-C.; Chang, C.-S.; Liang, W.-L.; Tsai, W.-F.; Ai, C.-F.; Lin, J.-F.

2012-07-01

187

Resolving Large Pre-glacial Valleys Buried by Glacial Sediment Using Electric Resistivity Imaging (ERI)  

NASA Astrophysics Data System (ADS)

Two-dimensional electric resistivity imaging (ERI) is the most exciting and promising geological tool in geomorphology and stratigraphy since development of ground-penetrating radar. Recent innovations in 2-D ERI provides a non-intrusive mean of efficiently resolving complex shallow subsurface structures under a number of different geological scenarios. In this paper, we test the capacity of ERI to image two large pre-late Wisconsinan-aged valley-fills in central Alberta and north-central Montana. Valley-fills record the history of pre-glacial and glacial sedimentary deposits. These fills are of considerable economical value as groundwater aquifers, aggregate resources (sand and gravel), placers (gold, diamond) and sometime gas reservoirs in Alberta. Although the approximate locations of pre-glacial valley-fills have been mapped, the scarcity of borehole (well log) information and sediment exposures make accurate reconstruction of their stratigraphy and cross-section profiles difficult. When coupled with borehole information, ERI successfully imaged three large pre-glacial valley-fills representing three contrasting geological settings. The Sand Coulee segment of the ancestral Missouri River, which has never been glaciated, is filled by electrically conductive pro-glacial lacustrine deposits over resistive sandstone bedrock. By comparison, the Big Sandy segment of the ancestral Missouri River valley has a complex valley-fill composed of till units interbedded with glaciofluvial gravel and varved clays over conductive shale. The fill is capped by floodplain, paludal and low alluvial fan deposits. The pre-glacial Onoway Valley (the ancestral North Saskatchewan River valley) is filled with thick, resistive fluvial gravel over conductive shale and capped with conductive till. The cross-sectional profile of each surveyed pre-glacial valley exhibits discrete benches (terraces) connected by steep drops, features that are hard to map using only boreholes. Best quality ERI results were obtained along the Sand Coulee and Onoway transects where the contrast between the bedrock and valley-fill was large and the surficial sediment was homogeneous. The effects of decreasing reliability with depth, 3-D anomalies, principles of equivalence and suppression, and surface inhomogeneity on the image quality are discussed.

Schmitt, D. R.; Welz, M.; Rokosh, C. D.; Pontbriand, M.-C.; Smith, D. G.

2004-05-01

188

Electrical resistivity of some Zintl phase and the precursors  

SciTech Connect

Resistivity measurements have been performed for electric characterization of the compounds Ba{sub 5}Sb{sub 3} and Ba{sub 5}Sb{sub 3}Cl, both with the Mn{sub 5}Si{sub 3} structure type, along with Ca{sub 5}Bi{sub 3} and Ca{sub 5}Bi{sub 3}F, both with the {beta}-Yb{sub 5}Sb{sub 3} structure type. These measurements were taken as a function of temperature using the four probe method on pressed polycrystalline pellets of the compounds. A sealed apparatus was developed for containing these air-sensitive compounds throughout the experiments. By a simple electron count, one extra electron in both Ba{sub 5}Sb{sub 3} and Ca{sub 5}Bi{sub 3} should occupy a conduction band, giving these compounds a metallic character. In the cases of Ba{sub 5}Sb{sub 3}Cl and Ca{sub 5}Bi{sub 3}F, the extra electron should bond to the halide, both filling the valence band and giving rise to semiconducting character. Ca{sub 5}Bi{sub 3}, Ca{sub 5}Bi{sub 3}F, and Ba{sub 5}Sb{sub 3}Cl were found to comply with the electron count prediction. Ba{sub 5}Sb{sub 3}, however, was found to be a semiconductor (E{sub g} = 0.30 eV) with a larger band gap than its corresponding chloride (E{sub g} = 0.09 eV).

Wolfe, L.

1990-09-21

189

In Vitro Resistance Profile of the Hepatitis C Virus NS3 Protease Inhibitor BI 201335  

PubMed Central

The in vitro resistance profile of BI 201335 was evaluated through selection and characterization of variants in genotype 1a (GT 1a) and genotype 1b (GT 1b) replicons. NS3 R155K and D168V were the most frequently observed resistant variants. Phenotypic characterization of the mutants revealed shifts in sensitivity specific to BI 201335 that did not alter susceptibility to alpha interferon. In contrast to macrocyclic and covalent protease inhibitors, changes at V36, T54, F43, and Q80 did not confer resistance to BI 201335.

Lagace, Lisette; White, Peter W.; Bousquet, Christiane; Dansereau, Nathalie; Do, Florence; Llinas-Brunet, Montse; Marquis, Martin; Massariol, Marie-Josee; Maurice, Roger; Spickler, Catherine; Thibeault, Diane; Triki, Ibtissem; Zhao, Songping

2012-01-01

190

Fabrication of intermetallic coatings for electrical insulation and corrosion resistance on high-temperature alloys  

SciTech Connect

Several intermetallic films were applied to high-temperature alloys (V alloys and 304, 316 stainless steels) to provide electrical insulation and corrosion resistance. Alloy grain growth at 1000 C for the V-5Cr-5Ti alloy was investigated to determine stability of the alloy substrate during coating formation by CVD or metallic vapor processes at 800-850 C. Film layers were examined by optical and scanning electron microscopy and by electron-energy-dispersive and XRD analysis; they were also tested for electrical resistivity and corrosion resistance. Results elucidated the nature of the coatings, which provided both electrical insulation and high-temperature corrosion protection.

Park, J.-H. [Argonne National Lab., IL (United States); Cho, W.D. [Utah Univ., Salt Lake City, UT (United States). Dept. of Metallurgical Engineering

1996-11-01

191

First-principles studies of electrical resistivity of iron under pressure.  

PubMed

We investigate the temperature and pressure dependences of the electrical resistivity, thermal conductivity and thermal diffusivity for bcc and hcp Fe using the low-order variational approximation and theoretical transport spectral functions calculated from the first-principles linear response linear-muffin-tin-orbital method in the generalized gradient approximation. The calculated values for the electrical resistivity show a strong increase with temperature and decrease with pressure, and are in agreement with high-temperature shock data. We also discuss the behavior of the electrical resistivity for the bcc?hcp phase transition. PMID:21411882

Sha, Xianwei; Cohen, R E

2011-02-02

192

Plume and lithologic profiling with surface resistivity and seismic tomography  

SciTech Connect

Improved surface-based geophysical technologies that are commercially available provide a new level of detail that can be used to guide ground water remediation. Surface-based multielectrode resistivity methods and tomographic seismic refraction techniques were used to image to a depth of approximately 30 m below the surface at the Natural and Accelerated Bioremediation Research Field Research Center. The U.S. Department of Energy (DOE) established the research center on the DOE Oak Ridge Reservation in Oak Ridge, Tennessee, to conduct in situ field-scale studies on bioremediation of metals and radionuclides. Bioremediation studies are being conducted on the saprolite, shale bedrock, and ground water at the site that have been contaminated with nitrate, uranium, technetium, tetrachloroethylene, and other contaminants (U.S. DOE 1997). Geophysical methods were effective in imaging the high-ionic strength plume and in defining the transition zone between saprolite and bedrock zones that appears to have a significant influence on contaminant transport. The geophysical data were used to help select the location and depth of investigation for field research plots. Drilling, borehole geophysics, and ground water sampling were used to verify the surface geophysical studies.

Watson, David B [ORNL; Doll, William E. [Battelle; Gamey, Jeff [Battelle; Sheehan, Jacob R [ORNL; Jardine, Philip M [ORNL

2005-03-01

193

An insight into the drug resistance profile & mechanism of drug resistance in Neisseria gonorrhoeae  

PubMed Central

Among the aetiological agents of treatable sexually transmitted diseases (STDs), Neissseria gonorrhoeae is considered to be most important because of emerging antibiotic resistant strains that compromise the effectiveness of treatment of the disease - gonorrhoea. In most of the developing countries, treatment of gonorrhoea relies mainly on syndromic management rather than the aetiological based therapy. Gonococcal infections are usually treated with single-dose therapy with an agent found to cure > 95 per cent of cases. Unfortunately during the last few decades, N. gonorrhoeae has developed resistance not only to less expensive antimicrobials such as sulphonamides, penicillin and tetracyclines but also to fluoroquinolones. The resistance trend of N. gonorrhoeae towards these antimicrobials can be categorised into pre-quinolone, quinolone and post-quinolone era. Among the antimicrobials available so far, only the third-generation cephalosporins could be safely recommended as first-line therapy for gonorrhoea globally. However, resistance to oral third-generation cephalosporins has also started emerging in some countries. Therefore, it has become imperative to initiate sustained national and international efforts to reduce infection and misuse of antibiotics so as to prevent further emergence and spread of antimicrobial resistance. It is necessary not only to monitor drug resistance and optimise treatment regimens, but also to gain insight into how gonococcus develops drug resistance. Knowledge of mechanism of resistance would help us to devise methods to prevent the occurrence of drug resistance against existing and new drugs. Such studies could also help in finding out new drug targets in N. gonorrhoeae and also a possibility of identification of new drugs for treating gonorrhoea.

Patel, Achchhe Lal; Chaudhry, Uma; Sachdev, Divya; Sachdeva, Poonam Nagpal; Bala, Manju; Saluja, Daman

2011-01-01

194

Development of an angular scanning system for sensing vertical profiles of soil electrical conductivity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Apparent soil electrical conductivity (EC**a**) is typically mapped to define soil spatial variability within an agricultural field. Knowledge of the vertical variability of EC**a** is desired to define site-specific behavior of the soil profile. A Pneumatic Angular Scanning System (PASS) was develo...

195

Optimal capacitor allocation in electrical distribution systems based on typical load profiles  

Microsoft Academic Search

This paper presents a genetic algorithm for the solution of capacitor allocation and control problems in electrical distribution systems. From the typical load profiles the proposed technique finds optimal locations for fixed and switched shunt capacitors. The objective function variables are the energy loss at distribution feeders and the costs of the capacitor banks including installation and the voltage constraints.

H. N. Alves; B. A. Souza; H. D. M. Braz; N. Kagan

2004-01-01

196

Plasma resistivity profile measurement from an external radio-frequency magnetic coil  

SciTech Connect

Plasma resistivity is obtained by measuring the change in circuit behavior from a simple loop placed externally to the plasma. The loop is part of a series-driven oscillator that can be tuned over a wide range of frequencies with a very low internal impedance. By varying the frequency, and observing both the detuning and loading of this circuit, the location and resistance of the screening currents can be determined. A two-dimensional resistive magnetohydrodynamic code calculation is performed to obtain both the plasma interaction with the oscillating field as well as the effects of nearby conductors. The plasma resistance in the numerical calculations is adjusted to match the data from the experiment and, in this way, obtain a measure of the plasma resistivity profile.

Slough, John T.; Andreason, Samuel P.; Milroy, Richard D. [University of Washington Seattle, Washington 98105 (United States)

2004-10-01

197

Effect of endurance and resistance training on regional fat mass and lipid profile.  

PubMed

The purpose of this study was to investigate the effect of 10-week of endurance training or resistance training on regional and abdominal fat, and in the lipid profile, examining the associations among the changes in body composition, weight, waist circumference and lipid profile. Body composition, waist circumference and lipid profile were analyzed in 26 volunteers healthy young men (age 22.5 ± 1.9 yr), randomly assigned to: endurance group (EG), resistance group (RG) or control group (CG). The EG significantly decreased after training the body weight, body mass index, total body fat and percentage of fat, fat and percentage of fat at the trunk and at the abdominal region and High-Density Lipoprotein. The RG significantly increased total lean mass and decreased total cholesterol, High-Density and Low- Density Lipoprotein. Close relationship were found among changes in weight, total lean mass, regional fat mass, waist circumference and changes in lipid profile (all p < 0.05). We concluded that 10-week of endurance training decreased abdominal and body fat in young men, while 10-week of resistance training increased total lean mass. These types of training had also effects on lipid profile that seem to be to some extent associated to changes in body composition; however it requires additional investigation. PMID:23822684

Perez-Gomez, Jorge; Vicente-Rodríguez, Germán; Ara Royo, Ignacio; Martínez-Redondo, Diana; Puzo Foncillas, José; Moreno, Luis A; Díez-Sánchez, Carmen; Casajús, José A

198

Insecticide resistance profiles and synergism in field populations of the German cockroach (Dictyoptera: Blattellidae) from Singapore.  

PubMed

The resistance profiles of 22 field-collected populations of the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae), from various localities in Singapore were determined by topical bioassay against novel and conventional insecticides from six classes: (1) pyrethroid (beta-cyfluthrin, deltamethrin), (2) carbamate (propoxur), (3) organophosphate (chlorpyrifos), (4) phenyl pyrazole (fipronil), (5) neonicotinoid (imidacloprid), and (6) oxadiazine (indoxacarb). Compared with a laboratory susceptible strain, resistance levels ranged from 3.0 to 468.0x for the pyrethroids, from 3.9 to 21.5x for the carbamate, from 1.5 to 22.8X for the organophosphate, from 1.0 to 10.0X for phenyl pyrazole, and were absent or low for the neonicotinoid (0.8-3.8x) and the oxadiazine (1.4-5.3x). One strain demonstrated broad-spectrum resistance to most of the insecticides. Synergism studies using piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) in combination with a discriminating dose (LD99) of selected insecticides were conducted to test for possible resistance mechanisms. Resistance to pyrethroid was reduced with PBO and DEF, suggesting the involvement of P450 monooxygenase and esterases in conferring resistance. Propoxur resistance also was suppressed with PBO and DEF, and coadministration of both synergists resulted in complete negation of the resistance, indicating the involvement of both P450 monooxygenase and esterase. In six B. germanica field strains evaluated, esterases were found to play a role in chlorpyrifos resistance, whereas the P450 monoxygenase involvement was registered in three strains. Additional resistance mechanisms such as kdr-type and Rdl mutation contributing toward pyrethroid and fipronil resistance, respectively, also may be involved in some strains in which the resistance levels were not affected by the synergists. We conclude that insecticide resistance is prevalent in field German cockroach populations in Singapore. PMID:20429463

Chai, Ru-Yuan; Lee, Chow-Yang

2010-04-01

199

Transport control in fusion plasmas by changing electric and magnetic field spatial profiles  

NASA Astrophysics Data System (ADS)

For magnetically confined plasmas in tokamaks, we have numerically investigated how Lagrangian chaos at the plasma edge affects the plasma confinement. Initially, we have considered the chaotic motion of particles in an equilibrium electric field with a monotonic radial profile perturbed by drift waves. We have showed that an effective transport barrier may be created at the plasma edge by modifying the electric field radial profile. In the second place, we have obtained escape patterns and magnetic footprints of chaotic magnetic field lines in the region near a tokamak wall with resonant modes due to the action of an ergodic magnetic limiter. For monotonic plasma current density profiles we have obtained distributions of field line connections to the wall and line escape channels with the same spatial pattern as the magnetic footprints on the tokamak walls.

Kroetz, T.; Marcus, F. A.; Roberto, M.; Caldas, I. L.; Viana, R. L.; da Silva, E. C.

2009-04-01

200

a Correlation Between the Aging Parameter and Electrical Resistivity for the Degraded 9 CR Steel  

NASA Astrophysics Data System (ADS)

It is advantageous to use a non-destructive evaluation (NDE) method to assess the mechanical properties of materials since conventional methods are time-consuming and usually require sampling from the material or component. In this study, an electrical resistivity method was attempted for the estimation of the creep damage of degraded 9Cr steel. The specimens with six different kinds of aging periods were prepared by an isothermal heat treatment at 690 °C. The electrical resistivity was determined by a standard DC four-point probe method at 24±0.5 °C. The home-made probe station and Burster 2304 were utilized for the resistance measurement. A correlation between the measured electrical resistivity and the tensile properties was studied. The electrical resistivity showed a declining tendency with the increase of aging time because the electrical resistivity is strongly dependent on the microstructural changes. A correlation between the electrical resistivity and aging parameter was established, which allows one to estimate the material degradation of 9Cr steel.

Baek, Un Bong; Lee, Yun-Hee; Na, Ho Jun; Nahm, Seung Hoon; Nam, Young Hyun

201

Fracture distribution and basement structure from measurements of electrical resistivity in the basement of the Cajon Pass Scientific Drillhole, California  

NASA Astrophysics Data System (ADS)

In-situ deep and shallow measurements of electrical resistivity recorded with the Dual Laterolog in the basement of the Cajon Pass scientific drillhole are compared with laboratory measurements of resistivity and porosity on fracture-free core samples. This comparison is the basis of a simple electrical model of the pore space of the rock from which both matrix and fracture porosity are derived. In parallel, the analysis of borehole electrical images obtained with the Formation Microscanner provides a means to identify the fractures that intersect the borehole wall, to evaluate their frequency, and to determine their orientation. Further processing of these images enables us to distinguish mineralized from fluid-filled fractures. The comparison of laterolog-derived fracture porosity, computed over a large volume of rock, with a pair of fracture intensity profiles obtained from the analysis of the two images of the borehole wall is the key of a new technique by which drillhole-related fractures (either due to hydraulic fracturing or to stress-induced borehole breakouts) and natural fractures (either open or mineralized) are discriminated. The fractures in the upper part of Cajon Pass basement are inferred from the analysis of in-situ resistivity measurements as mostly steep and mineralized.

Pezard, Philippe A.; Anderson, Roger N.; Howard, James J.; Luthi, Stefan M.

202

Effect of hydrogen on the electrical resistance of palladium  

Microsoft Academic Search

A four-point constant-current technique was used to determine the change in resistivity with time at 298 K for Pd-wires which had been annealed for 20 h at 1000 K in both argon and hydrogen atmospheres. A large resistivity decrement was discovered in the H2-annealed wires which was not obtained in the case of the Ar-annealed specimens. The resistivity decrement has

Z. R. Xu; P. Maroevic; R. B. McLellan

1998-01-01

203

An electrically modifiable synapse array of resistive switching memory  

Microsoft Academic Search

This paper describes the resistive switching of a cross-point cell array device, with a junction area of 100 nm × 100 nm, fabricated using ultraviolet nanoimprinting. A GdOx and Cu-doped MoOx stack with platinum top and bottom electrodes served as the resistive switching layer, which shows analog memory characteristics with a resistance ratio greater than 10. To demonstrate a neural

Hyejung Choi; Heesoo Jung; Joonmyoung Lee; Jaesik Yoon; Dong-jun Seong; Wootae Lee; Musarrat Hasan; Gun-Young Jung; Hyunsang Hwang

2009-01-01

204

Update of Thermal Conductivity and Electrical Resistivity of Electrolytic Iron, Tungsten, and Stainless Steel.  

National Technical Information Service (NTIS)

An update is given of the thermal conductivity and electrical resistivity of the metals: electrolytic iron, tungsten, and stainless steel. This document describes the measurement effort that has occurred since the establishment of these SRM's. New data ar...

J. G. Hust A. B. Lankford

1984-01-01

205

The Use of Electrical Resistivity to Determine Porosity of Marine Sediments.  

National Technical Information Service (NTIS)

A method using electrical resistivity measurements to determine the in situ porosity of marine sediments was investigated in the laboratory, and equipment for this purpose was designed, fabricated and tested. Formation Factor-porosity relationships determ...

R. A. Erchul

1972-01-01

206

Cost and Performance Review of Electrical Resistance Heating (ERH) for Source Treatment.  

National Technical Information Service (NTIS)

This cost and performance report is a critical review of technical and performance data from four recent Navy projects and one National Aeronautic and Space Administration (NASA) project involving the use of Electrical Resistance Heating (ERH) for treatme...

A. Gavaskar M. Bhargava W. Condit

2007-01-01

207

Design and performance of low-thermal-resistance, high-electrical-isolation heat intercept connections.  

National Technical Information Service (NTIS)

Electrical conductors often require the removal of heat produced by their normal operation. The heat can be removed by mechanical connection to a refrigeration source. Such connections require both effective heat removal (low thermal resistance) and effec...

R. C. Niemann J. D. Gonczy P. E. Phelan T. H. Nicol

1994-01-01

208

Imaging artificial salt water infiltration using electrical resistivity tomography constrained by geostatistical data  

NASA Astrophysics Data System (ADS)

? Surface electrical resistivity tomography to image salt water infiltration. ? Borehole-derived variogram used as inversion constraints. ? Significant improvement compared to standard smoothness-constrained imaging. ? Plume scale imaging (200 m). ? Validated results and more reliable TDS content estimates.

Hermans, Thomas; Vandenbohede, Alexander; Lebbe, Luc; Martin, Roland; Kemna, Andreas; Beaujean, Jean; Nguyen, Frederic

2012-05-01

209

An Ultra-Precise System for Electrical Resistivity Tomography Measurements  

SciTech Connect

The objective of this research was to determine the feasibility of building and operating an ERT system that will allow measurement precision that is an order of magnitude better than existing systems on the market today and in particular if this can be done without significantly greater manufacturing or operating costs than existing commercial systems. Under this proposal, we performed an estimation of measurement errors in galvanic resistivity data that arise as a consequence of the type of electrode material used to make the measurements. In our laboratory, measurement errors for both magnitude and induced polarization (IP) were estimated using the reciprocity of data from an array of electrodes as might be used for electrical resistance tomography using 14 different metals as well as one non-metal - carbon. In a second phase of this study, using archival data from two long-term ERT surveys, we examined long-term survivability of electrodes over periods of several years. The survey sites were: the Drift Scale Test at Yucca Mountain, Nevada (which was sponsored by the U. S. Department of Energy as part of the civilian radioactive waste management program), and a water infiltration test at a site adjacent to the New Mexico Institute of Mines and Technology in Socorro, New Mexico (sponsored by the Sandia/Tech vadose program). This enabled us to compare recent values with historical values and determine electrode performance over the long-term as well as the percentage of electrodes that have failed entirely. We have constructed a prototype receiver system, made modifications and revised the receiver design. The revised prototype uses a new 24 bit analog to digital converter from Linear Technologies with amplifier chips from Texas Instruments. The input impedance of the system will be increased from 107 Ohms to approximately 1010 Ohms. The input noise level of the system has been decreased to approximately 10 Nanovolts and system resolution to about 1 Nanovolt at the highest gain range of 125 to 1. The receiver also uses very high precision and high temperature stability components. The goal is to improve the accuracy to better than 0.1%. The system has more receiver channels, eight, to allow efficient data collection at lower base frequencies. We are also implementing a frequency-domain acquisition mode in addition to the time-domain acquisition mode used in the earlier systems. Initial field tests were started in the fall of 2008. We conducted tests on a number of types of cable commonly used for resistivity surveys. A series of different tests were designed to determine if the couplings were primarily resistive, capacitive, or inductive in nature and to ascertain that the response was due to the cable cross-talk and did not depend on the receiver electronics. The results show that the problem appears to be primarily capacitive in nature and does not appear to be due to problems in the receiver electronics. Thus a great deal of emphasis has been placed on finding appropriate cables as well as stable electrodes that have low contact impedance at the very low current flows observed at the receiver. One of the issues in survey design and data collection has been determining how long one must wait before using the same electrode as a transmitter and as a receiver. A series of tests was completed in the laboratory sand tank where four-electrode measurements were made using the same dipole transmitters and dipole receivers (the dipoles used adjacent electrodes). For each data series, a single set of normal measurements were collected with no reciprocals and electrodes were never reused as a receiver after being used as a transmitter. After waiting a specified length of time, the reciprocal measurements were collected using a schedule of measurements. The order of this second schedule was rearranged such that if this second set of measurements were performed without first using the normal schedule, no electrode would be used as a receiver after being used as a transmitter. For this study, we cannot conclude that increasing the

LaBrecque, Douglas J; Adkins, Paula L

2008-12-09

210

Profiling of circulating microRNAs after a bout of acute resistance exercise in humans.  

PubMed

Recent studies have revealed a new aspect of physiological regulation in which microRNAs (miRNAs) play fundamental roles in diverse biological and pathological processes. Furthermore, it was recently discovered that miRNAs are stably secreted into blood and that circulating miRNAs may play important roles in cell-cell communication. Here, we examined whether the circulating miRNA profile is affected by acute resistance exercise. Twelve males performed a resistance exercise session (bench press and leg press), consisting of five sets of 10 repetitions at 70% of maximum strength, with a 1 min rest between sets. Blood samples were taken before exercise, and at 0 and 60 min, 1 day, and 3 days after exercise. The circulating miRNA profile was determined by microarray analysis. Quantitative real-time PCR confirmed that the miR-149* level increased three days after resistance exercise. In contrast, the miR-146a and miR-221 levels decreased three days after resistance exercise. Our findings suggest that circulating miRNA levels change in response to acute resistance exercise, and miRNAs may play important roles in resistance-exercise-induced adaptation. PMID:23923026

Sawada, Shuji; Kon, Michihiro; Wada, Shogo; Ushida, Takashi; Suzuki, Katsuhiko; Akimoto, Takayuki

2013-07-29

211

Negative resist profiles in 248 nm photolithography: experiment, modelling and simulation  

NASA Astrophysics Data System (ADS)

We consider the effects both of exposure energy dose and of developer temperature on the developed negative resist profiles. The spin-formatted resist film tends to have macromolecules oriented parallel to the substrate surface. The orientation of the resist macromolecules introduces an anisotropic component to the etch rate: higher in the direction parallel to the substrate surface and lower in the perpendicular one. We performed a series of experiments for 400 nm pitch periodic and isolated lines on Shipley SNR-248 negative resist coated Si wafers using a stepper and a deep UV source at 248 nm. We obtained scanning electron micrographs for various developer temperatures and exposure doses. The variation of the lateral etch rate manifested itself in sidewall profile slopes. We used Dill's ABC parameter model to model and quantify the exposure, and cellular automata to model the resist cross-linking during post-exposure bake and the resist etching. Simulation using an algorithm based on this model validated the experimental results.

Karafyllidis, I.; Hagouel, P. I.; Neureuther, A. R.

1998-06-01

212

High-temperature electrical resistivity of rare-earth metals with variable valence  

SciTech Connect

The electrical resistivity of compounds of rare-earth metals at high temperatures is calculated on the basis of allowance for the background mechanism of scattering and the hybridization of local electron states with the states of conduction electrons. An analytic expression is obtained for resistivity in a strong hybridization approximation. It follows from the expression that electrical resistivity may have a negative temperature coefficient within a broad range of high temperatures. The use of a three-band (s, d, f) model makes it possible to explain experimental data on the resistivity of certain rare-earth metals, particularly the connection between the sign of the temperature coefficient of electrical resistivity and the curvature of the relation (T).

Povzner, A.A.; Abel'skii, S.S.

1986-11-01

213

Electrical resistivity behavior of substituted perovskite manganates sintered at different temperatures  

SciTech Connect

Temperature dependence of the electrical resistivity of La{sub 1{minus}x}Ca{sub x}MnO{sub 3} (x = 0.2, 0.3) samples sintered at two different temperatures are compared to understand the origin of the double-maxima-type resistivity curves of some doped perovskite manganates reported in the literature. It is shown that compositional inhomogeneity is responsible for the anomalous electrical properties of the substituted manganate samples processed at low temperatures.

Joy, P.A.; Kumar, P.S.A.; Date, S.K.

1999-12-01

214

Relationship between structure and electrical resistivity in nano-structured copper-containing carbon films  

Microsoft Academic Search

The microstructure evolution of carbon\\/copper (C\\/Cu) films and its relation to the variation of film electrical resistivity has been studied. The films doped with copper in the range of 1.4–22.6at.% Cu, were deposited by dc magnetron sputtering of composite graphite–copper target. The microstructure of films was studied by Raman spectroscopy and electron diffraction. The electrical resistivity was measured parallel and

A. A. Onoprienko; I. B. Yanchuk; I. A. Kossko

2010-01-01

215

High pressure electrical resistivity behaviour on nano-crystalline vacancy doped perovskite manganites  

Microsoft Academic Search

We report here for the first time, the pressure dependence of the electrical resistivity of vacancy-doped nano-crystalline manganites up to 2GPa at room temperature. The nano-crystalline samples with vacancy doping at La- and Mn-sites, respectively, were synthesized by sol–gel technique and particle size was determined by width in the X-ray diffraction peaks. The pressure dependent electrical resistivity measurements on La-deficient

Manoj Kumar; Usha Chandra; G. Parthasarathy

2006-01-01

216

Measurement of Specific Heat Capacity and Electrical Resistivity of Industrial Alloys Using Pulse Heating Techniques  

Microsoft Academic Search

The determination of the specific heat capacity and electrical resistivity of Inconel 718, Ti-6Al-4V, and CF8M stainless steel, from room temperature to near the melting temperatures of the alloys, is described. The method is based on rapid resistive self-heating of a solid cylindrical specimen by the passage of a short-duration electric current pulse through it while simultaneously measuring the pertinent

D. Basak; R. A. Overfelt; D. Wang

2003-01-01

217

Electrical resistance change method for damage monitoring of woven graphite/epoxy laminate  

NASA Astrophysics Data System (ADS)

This paper examines damage monitoring for woven graphite/epoxy laminate by means of an electrical resistance change method. The method has been proposed by the authors and successfully applied to cross-ply and quasi-isotropic laminates; the method has yet to be applied to woven laminates. Therefore, a woven graphite/epoxy composite is selected for the target material of the electrical resistance change method to identify the damage. Beam type specimens consisting of woven laminates are the focus of this paper. The influence of a different electrical property of woven laminate upon the electrical resistance change is investigated both analytically and experimentally, and the condition of the electrical contact between the electrode and the specimen is investigated experimentally. For the purpose of identification, the response surface is adopted as a solving method for the inverse problem. As a result, the method shows excellent performance for estimating delamination locations and sizes.

Hirano, Y.; Todoroki, A.

2006-04-01

218

In Vitro Cross-Resistance Profile of Nucleoside Reverse Transcriptase Inhibitor (NRTI) BMS-986001 against Known NRTI Resistance Mutations.  

PubMed

BMS-986001 is a novel HIV nucleoside reverse transcriptase inhibitor (NRTI). To date, little is known about its resistance profile. In order to examine the cross-resistance profile of BMS-986001 to NRTI mutations, a replicating virus system was used to examine specific amino acid mutations known to confer resistance to various NRTIs. In addition, reverse transcriptases from 19 clinical isolates with various NRTI mutations were examined in the Monogram PhenoSense HIV assay. In the site-directed mutagenesis studies, a virus containing a K65R substitution exhibited a 0.4-fold change in 50% effective concentration (EC50) versus the wild type, while the majority of viruses with the Q151M constellation (without M184V) exhibited changes in EC50 versus wild type of 0.23- to 0.48-fold. Susceptibility to BMS-986001 was also maintained in an L74V-containing virus (0.7-fold change), while an M184V-only-containing virus induced a 2- to 3-fold decrease in susceptibility. Increasing numbers of thymidine analog mutation pattern 1 (TAM-1) pathway mutations correlated with decreases in susceptibility to BMS-986001, while viruses with TAM-2 pathway mutations exhibited a 5- to 8-fold decrease in susceptibility, regardless of the number of TAMs. A 22-fold decrease in susceptibility to BMS-986001 was observed in a site-directed mutant containing the T69 insertion complex. Common non-NRTI (NNRTI) mutations had little impact on susceptibility to BMS-986001. The results from the site-directed mutants correlated well with the more complicated genotypes found in NRTI-resistant clinical isolates. Data from clinical studies are needed to determine the clinically relevant resistance cutoff values for BMS-986001. PMID:23979732

Li, Zhufang; Terry, Brian; Olds, William; Protack, Tricia; Deminie, Carol; Minassian, Beatrice; Nowicka-Sans, Beata; Sun, Yongnian; Dicker, Ira; Hwang, Carey; Lataillade, Max; Hanna, George J; Krystal, Mark

2013-08-26

219

An appraisal of the electrical resistance method for assessing root surface area  

PubMed Central

Electrical resistances of roots and stems of hydroponically raised willows (Salix schwerinii) were studied and related to root morphology. Willow cuttings with and without roots were set in a constant electric field (effective voltage of 0.1 V, sine-AC, 128 Hz) in a hydroponic solution. The electrical resistance of different components in the measurement system was measured and analysed in relation to root surface area in contact with the cultivation solution. Axial resistivities of single root segments and of stems were measured. The results showed that the resistance decreased in relation to an increase in the contact surface area of the roots with the solution. The resistance depended strongly on the contact area of the stem with the solution, however, thus causing bias in the evaluation of root surface area. This work is a new contribution for the understanding of current pathways in the root system as exposed to an external electric field and for developing a non-destructive method to study plant roots accordingly. It may be concluded that the electrical resistance method is a useful non-destructive method to study roots and their physiological properties. Electrical analogues for roots and stem comprising resistors are discussed in relation to in situ measurements.

Cao, Yang; Repo, Tapani; Silvennoinen, Raimo; Lehto, Tarja; Pelkonen, Paavo

2010-01-01

220

Correlation of Cell Membrane Lipid Profiles with Daptomycin Resistance in Methicillin-Resistant Staphylococcus aureus  

PubMed Central

We compared the cell membrane (CM) lipid composition among nine well-characterized daptomycin-susceptible (Daps)/Dap-resistant (Dapr) methicillin-resistant Staphylococcus aureus (MRSA) strain pairs. Compared to the 9 Daps parental strains, Dapr strains (with or without mprF-yycFG mutations) exhibited significantly reduced phosphatidylglycerol (PG) content (P < 0.01), significantly increased total synthesis of lysyl-PG (LPG) (P < 0.01), and reduced carotenoid content (P < 0.05 for 5/9 strains). There were no significant changes in LPG flipping, cardiolipin content, or fatty acid composition among strain pairs.

Bayer, Arnold S.

2013-01-01

221

Strain-dependent electrical resistance of multi-walled carbon nanotube/polymer composite films  

NASA Astrophysics Data System (ADS)

The strain-dependent electrical resistance characteristics of multi-walled carbon nanotube (MWCNT)/polymer composite films were investigated. In this research, polyethylene oxide (PEO) is used as the polymer matrix. Two representative volume fractions of MWCNT/PEO composite films were selected: 0.56 vol% (near the percolation threshold) and 1.44 vol% (away from the percolation threshold) of MWCNT. An experimental setup which can measure electrical resistance and strain simultaneously and continuously has been developed. Unique and repeatable relationships in resistance versus strain were obtained for multiple specimens with different volume fractions of MWCNT. The overall pattern of electrical resistance change versus strain for the specimens tested consists of linear and nonlinear regions. A resistance change model to describe the combination of linear and nonlinear modes of electrical resistance change as a function of strain is suggested. The unique characteristics in electrical resistance change for different volume fractions imply that MWCNT/PEO composite films can be used as tunable strain sensors and for application into embedded sensor systems in structures.

Park, Myounggu; Kim, Hyonny; Youngblood, Jeffrey P.

2008-02-01

222

Electrical resistivity survey to search for a recent clandestine burial of a homicide victim, UK  

Microsoft Academic Search

This case report details an electrical resistivity survey to assist the search for a suspected 1-year-old clandestine burial of a murder victim in North Wales in the UK. Conventional search techniques (victim recovery dogs and probing) proved unsuccessful, and with a significant survey area and a high clay content soil precluding GPR as a geophysical search method, a resistivity survey

Jamie K. Pringle; John R. Jervis

2010-01-01

223

Electrical circuit model for quantifying the proliferation resistance of nuclear fuel cycles  

Microsoft Academic Search

For quantifying the proliferation resistance of nuclear fuel cycles, the proliferation resistance index was modeled in imitation of an electrical circuit and linked with multi-attribute utility theory. As a case study, this model was applied to Korean nuclear fuel cycle alternatives including DUPIC(Direct Use of spent PWR fuel In CANDU) fuel cycle. The main features of the model are that

Kun Jai Lee

2000-01-01

224

Experimental characterizations and modeling of electrical resistance in hydrate bearing sediments  

Microsoft Academic Search

Electrica l resistance is an important method in characterization of oil\\/gas reservoirs, and can also be applied to gas hydrate bearing formations. Formation of gas hydrate has many significant impacts on subsea sediments. Since electric ions are excluded in hydrate, hydrate formation can change the distribution and mobility of electrolytes in subsea sediments, which will affect the resistance of the

Zhang Weidong; Liu Yongjun; Ren Shaoran; Wang Ruihe

2011-01-01

225

Study on Optimal Location of a Resistive SFCL Applied to an Electric Power Grid  

Microsoft Academic Search

This paper describes a study on the optimal location of a resistive superconducting fault current limiter (SFCL) applied to an electric power grid. The resistive SFCL, which is designed to provide the quick system protection in the event of a fault, can have different effects on the planning and operation of a power system depending on its location. To select

Byung Chul Sung; Dong Keun Park; Jung-Wook Park; Tae Kuk Ko

2009-01-01

226

Electric-field-induced resistance switching universally observed in transition-metal-oxide thin films  

Microsoft Academic Search

We show that polarity-dependent, nonvolatile resistance switching by electric field occurs in the thin film of various transition-metal oxides in almost the same manner. This result indicates that, contrary to the general acceptance, perovskite manganite is by no means a special compound for this phenomenon. It is also suggested that the resistance switching is not dominated by a detailed electronic

M. Hamaguchi; K. Aoyama; S. Asanuma; Y. Uesu; T. Katsufuji

2006-01-01

227

Apparatus for Contactless Measurement of the Electrical Resistance of a Conductor.  

National Technical Information Service (NTIS)

An apparatus for contactlessly measuring the electrical resistance per unit length of a low-resistance test conductor (e.g., wire or cable) at a selected measurement frequency, which includes a coaxial cavity structure having a central cavity region defin...

R. E. Richardson

1997-01-01

228

Modeling the magnetosphere for northward interplanetary magnetic field: Effects of electrical resistivity  

Microsoft Academic Search

We develop a simple analytic model and use global simulations of Earth's magnetosphere to investigate the effects of electrical resistivity on the topology of the magnetosphere for northward interplanetary magnetic field (IMF). We find that for low resistivity values (<~104Omegam) the magnetosphere remains open after 6 hours of northward IMF. For larger values (>~2×105Omegam) the magnetic flux of the tail

Joachim Raeder

1999-01-01

229

Effects of adsorption on the infrared reflectance and electrical resistivity of epitaxial copper films  

Microsoft Academic Search

Monolayer adsorption on a metal generally increases its dc electrical resistivity and decreases its optical reflectance. Usually these effects are interpreted with a model of free electrons with random point scatterers. Adsorption modifies the electrical conductivity of the metal in the near surface, primarily because the conduction electrons in the metal scatter diffusely from the perturbed potential introduced by adsorbates.

Ching-Ling Hsu

2001-01-01

230

Hydrogeological application of electrical resistivity tomography: Implementing a fixed-electrode strategy  

Microsoft Academic Search

The requirements of environmental assessments and of understanding and monitoring in-situ mass and heat processes in porous media have led to the development of geophysical methods for remote mapping and monitoring of contaminant plumes and fluid migration. With the possible exception of seismic approaches, electrical methods known as Electrical Resistivity Tomography (ERT) have become the most widely studied and used

Parsa Pezeshkpour

1999-01-01

231

Electrothermal analysis of electric resistance spot welding processes by a 3-D finite element method  

Microsoft Academic Search

Electric resistance spot welding which is an important process in auto-body assebly is simulated by a 3-D finite element code developed. The main interest in the simulation is the quality of welding and the durability of electrodes, which needs electrothermal analysis for temperature distribution in both electrodes and welded sheets. A finite element formulation is derived for both electric analysis

H. Huh; W. J. Kang

1997-01-01

232

Method and device with adjustable focusing for measuring the electric resistivity of geological formations  

SciTech Connect

The method of the invention comprises determining the variation of the electric potential on both sides of a central electrode in a borehole, detecting the two levels of the borehole where the potential gradient is zero, and measuring the electric resistivity of the geological formation between these two levels.

Desbrandes, R.

1983-10-25

233

Spatial and temporal monitoring of soil water content with an irrigated corn crop cover using surface electrical resistivity tomography  

NASA Astrophysics Data System (ADS)

A nondestructive and spatially integrated multielectrode method for measuring soil electrical resistivity was tested in the Beauce region of France during a period of corn crop irrigation to monitor soil water flow over time and in two-dimensional (2-D) with simultaneous measurements of soil moisture and thermal profiles. The results suggested the potential of surface electrical resistivity tomography (ERT) for improving soil science and agronomy studies. The method was able to produce a 2-D delimitation of soil horizons as well as to monitor soil water movement. Soil drainage through water uptake by the roots, the progression of the infiltration front with preferential flow zones, and the drainage of the plowed horizon were well identified. At the studied stage of corn development (3 months) the soil zones where infiltration and drainage occurred were mainly located under the corn rows. The structural soil characteristics resulting from agricultural practices or the passage of agricultural equipment were also shown. Two-dimensional sections of soil moisture content were calculated using ERT. The estimates were made by using independently established "in situ" calibration relationships between the moisture and electrical resistivity of typical soil horizons. The thermal soil profile was also considered in the modeling. The results showed a reliable linear relationship between the calculated and measured water contents in the crop horizon. The precision of the calculation of the specific soil water content, quantified by the root mean square error (RMSE), was 3.63% with a bias corresponding to an overestimation of 1.45%. The analysis and monitoring of the spatial variability of the soil moisture content with ERT represent two components of a significant tool for better management of soil water reserves and rational irrigation practices.

Michot, Didier; Benderitter, Yves; Dorigny, Abel; Nicoullaud, Bernard; King, Dominique; Tabbagh, Alain

2003-05-01

234

Microbial uropathogens and their antibiotic resistance profile from hospitalized patients in Central Alabama.  

PubMed

Urinary tract infections remain a common problem in inpatient care. They are highly challenging to provide effective initial therapy without sensitivity data. The purpose of this study was to survey the uropathogens and their sensitivity profile at a hospital in Central Alabama and to guide experiential antibiotic selection. This was the first reported study on bacterial uropathogens and their antibiotic resistance profile at this Central Alabama hospital. The survey period was between July 2009 and June 2010, a total of 473 urine cultures were reviewed and susceptibility testing was determined using the Clinical and Laboratory Standards Institute (CLSI) microdilution method. The results indicated that Escherichia coli (45.5%) was the most common organism, followed by Klebsiella pneumoniae (18.2%), Pseudomonas aeruginosa (10.1%), Proteus mirabilis (7.8%), Enterobacter cloacae (4.2%), methicillin-resistant Staphylococcus aureus (3.0%), Klebsiella oxytoca and Citrobacter freundii (1.5%), Morganella morganii (1.3%), and the other species (7.0%). For the 215 E. coli isolates, imipenem and cephalosporins (except for cefazolin) had the highest sensitivity (99-100%, P < 0.05). In contrast, ampicillin had the highest resistance (57%, P < 0.05) as compared to other antibiotics (about 30%) including ampicillin/ sulbactam, ciprofloxacin, levofloxacin, tetracycline, and trimethoprim/sulfamethoxazole. The major finding of this study was that ciprofloxacin, levofloxacin and trimethoprim/sulfamethoxazole had comparable sensitivity patterns for Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Enterobacter cloacae, the most common uropathogens at this Central Alabama hospital. Additionally, this study found that E. coli had a resistant rate of 31% to ciprofloxacin and levofloxacin compared to the resistance rate of 28.4% and 15.8% in earlier reports (Lee et al. 2010; Rattanaumpawan et al. 2010), likely indicating the continuing evolution of resistance due to antibiotic exposure. It is imperative to monitor the resistance of P. aeruginosa considering their high resistance to imipenem found in this study. PMID:23330509

Qian, Li; Camara, Tracy; Taylor, J Kyle; Jones, Kathy W

2012-01-01

235

In situ electrical resistivity and bulk porosity of the oceanic crust Costa Rica Rift  

Microsoft Academic Search

In situ electrical resistivity was measured in DSDP Hole 504B to a depth of 1,013 m into oceanic basement. Apparent resistivities are about 10 Omega m in about 600 m of pillow lavas, sharply increasing to nearly 1,000 Omega m in the underlying dykes. Bulk porosities calculated from resistivities show a distinct layering, apparently corresponding to geophysical layers 2A, 2B

Keir Becker; R. P. von Herzen; T. J. G. Francis; R. N. Anderson; J. Honnorez; A. C. Adamson; J. C. Alt; R. Emmermann; P. D. Kempton; H. Kinoshita; C. Laverne; M. J. Mottl; R. L. Newmark

1982-01-01

236

Magnetic interference effect in the electrical resistivity of amorphous simple metal alloys: Mg-Zn(Gd)  

Microsoft Academic Search

Electrical resistivity in an amorphous simple metal alloy host Mg70Zn30 containing up to 4 at.%Gd has been studied. the 'non Kondo' upturn in resistivity at low temperature is interpreted in terms of conduction electrons scattering from correlated pairs of spins. A universal behaviour of excess resistivity per at.%Gd versus reduced temperature T\\/ theta s (where theta s marks the onset

S. J. Poon; P. L. Dunn; L. M. Smith

1982-01-01

237

Electrical properties of materials for elevated temperature resistance strain gage application. Ph. D. Thesis  

Microsoft Academic Search

The objective was to study the electrical resistances of materials that are potentially useful as resistance strain gages at 1000 C. Transition metal carbides and nitrides, boron carbide and silicon carbide were selected for the experimental phase of this research. Due to their low temperature coefficient of resistance and good stability, TiC, ZrC, B sub 4 C and beta-SiC are

Lei

1987-01-01

238

Electric-pulse-induced resistance switching effect and related properties in manganite oxide structures  

Microsoft Academic Search

Rapid advances in information technology rely on high-speed and large-capacity nonvolatile memories. The novel electric-pulse-induced resistance (EPIR) switching effect has been obtained in the Pr0.7Ca 0.3MnO3 (PCMO) film sandwiched between two metal electrodes. The EPIR effect encompasses the reversible change of resistance of the PCMO device under the application of short, low voltage pulses. This reversible resistance switching at room

Zhongwen Xing

2008-01-01

239

Geophysical investigations at the Istron archaeological site, eastern Crete, Greece using seismic refraction and electrical resistivity tomography  

NASA Astrophysics Data System (ADS)

The subsurface characteristics of the archaeological site of Priniatikos Pyrgos at Istron, Eastern Crete were studied through the combined use of seismic and electrical tomography techniques. Twenty-nine seismic refraction profiles were applied to determine soil thickness and bedrock geometrical characteristics. First arrivals were picked and a 3D algorithm of seismic tomography was used to invert the travel times. To confirm the reliability of the final results a checkboard test was used. Part of the seismic area was overlapped with six electrical resistivity tomography sections. The ERT data were used to validate the resulted tomographic images. The integrated application of these tomographic methods enhanced the knowledge regarding the geological conditions and contributed in the archaeo-environmental reconstruction of Istron area by providing indications regarding the ancient harbour of the nearby settlement.

Shahrukh, M.; Soupios, P.; Papadopoulos, N.; Sarris, A.

2012-12-01

240

Temporal profiling of the transcriptional basis for the development of corticosteroid-induced insulin resistance in rat muscle  

Microsoft Academic Search

Elevated systemic levels of glucocorticoids are causally related to peripheral insulin resistance. The pharmacologi- cal use of synthetic glucocorticoids (corticosteroids) often results in insulin resistance\\/type II diabetes. Skeletal muscle is responsible for close to 80% of the insulin- induced systemic disposal of glucose and is a major target for glucocorticoid-induced insulin resistance. We used Affymetrix gene chips to profile the

Richard R Almon; Debra C DuBois; Jin Y Jin; William J Jusko

2005-01-01

241

Constriction Resistance Behavior of a Tin or Silver Plated Layer for an Electrical Contact  

NASA Astrophysics Data System (ADS)

Electrical contacts are an important part of electrical circuits and many reliability problems are related to electrical contact failure. It is important to investigate the relationship between load and contact resistance which is an important factor of contact reliability. In this study, the effect of plated material and plated thickness on contact resistance was examined. The samples were constructed of a copper alloy with tin or silver plating. Contact configuration was hemispherical-flat contact. The contact resistance was measured by using a four-probe method with a load up to 40N. The relation between indentation contact area (i.e. apparent contact area) and contact resistance was determined. As experimental results, the contact resistance depends on the indentation of the contact area. In the same contact area, tin-plated samples have higher resistance than those that are silver-plated due to their own resistivity. The constriction resistance of a plated layer, which depends on contact area, plated material and plated thickness, is analyzed by a theoretical solution, which is shown by R=??/2a, using a surface resistance coefficient ?. The theoretical results show almost good agreement with the experimental results. Thus, the indentation contact area (i.e. apparent contact area) is almost the same as the real contact area in this study.

Sawada, Shigeru; Shimizu, Kaori; Hattori, Yasuhiro; Tamai, Terutaka

242

Methods for detecting and locating leaks in containment facilities using electrical potential data and electrical resistance tomographic imaging techniques  

DOEpatents

Methods are provided for detecting and locating leaks in liners used as barriers in the construction of landfills, surface impoundments, water reservoirs, tanks, and the like. Electrodes are placed in the ground around the periphery of the facility, in the leak detection zone located between two liners if present, and/or within the containment facility. Electrical resistivity data is collected using these electrodes. This data is used to map the electrical resistivity distribution beneath the containment liner or between two liners in a double-lined facility. In an alternative embodiment, an electrode placed within the lined facility is driven to an electrical potential with respect to another electrode placed at a distance from the lined facility (mise-a-la-masse). Voltage differences are then measured between various combinations of additional electrodes placed in the soil on the periphery of the facility, the leak detection zone, or within the facility. A leak of liquid through the liner material will result in an electrical potential distribution that can be measured at the electrodes. The leak position is located by determining the coordinates of an electrical current source pole that best fits the measured potentials with the constraints of the known or assumed resistivity distribution.

Daily, William D. (Livermore, CA); Laine, Daren L. (San Anotonio, TX); Laine, Edwin F. (Penn Valley, CA)

2001-01-01

243

Methods for detecting and locating leaks in containment facilities using electrical potential data and electrical resistance tomographic imaging techniques  

DOEpatents

Methods are provided for detecting and locating leaks in liners used as barriers in the construction of landfills, surface impoundments, water reservoirs, tanks, and the like. Electrodes are placed in the ground around the periphery of the facility, in the leak detection zone located between two liners if present, and/or within the containment facility. Electrical resistivity data is collected using these electrodes. This data is used to map the electrical resistivity distribution beneath the containment liner between two liners in a double-lined facility. In an alternative embodiment, an electrode placed within the lined facility is driven to an electrical potential with respect to another electrode placed at a distance from the lined facility (mise-a-la-masse). Voltage differences are then measured between various combinations of additional electrodes placed in the soil on the periphery of the facility, the leak detection zone, or within the facility. A leak of liquid though the liner material will result in an electrical potential distribution that can be measured at the electrodes. The leak position is located by determining the coordinates of an electrical current source pole that best fits the measured potentials with the constraints of the known or assumed resistivity distribution.

Daily, William D. (Livermore, CA); Laine, Daren L. (San Antonio, TX); Laine, Edwin F. (Alamo, CA)

1997-01-01

244

Changes in lipid profile and insulin resistance in obese patients after Scopinaro biliopancreatic diversion  

Microsoft Academic Search

Background  Obesity is associated with many cardiovascular risk factors. The aim of this study is to evaluate the effect of bariatric\\u000a surgery (BS) in lipid profile and insulin resistance in obese patients.\\u000a \\u000a \\u000a \\u000a Material and Methods  We studied changes in lipid parameters glucose, insulin, and insulin resistance (IR) before biliopancreatic diversion and\\u000a 3, 6, 12, 18, and 24 months after surgery, in 115 obese

Magdalena Vila; Olga Ruíz; Mar Belmonte; Maria Riesco; Antonia Barceló; Gerardo Perez; Jose Moreiro; Ramon Salinas

2009-01-01

245

The effect of heat stress on the antibacterial resistance and plasmid profile in Escherichia coli isolates.  

PubMed

In order to study the effect of heat stress on the antibacterial resistance and plasmid profile in Escherichia coli, thirty E. coli were isolated from sheep liver. Antibiotic susceptibility test were done by antibiotic disc diffusion method using filter paper disc on two 24 h cultures of each isolate which grown at 37 and 43 degrees C simultaneously in BHI Broth (Merck VM460193 531). The isolates which grown at 43 degrees C were under heat stress during their growth. Ten commonly used antibiotics, viz., ampicillin, erythromycin, neomycin, trimethoprim-sulfamethoxazol, lincospectine, tetracycline, gentamycin, flumequine, vancomycin and Tiamulin (Padtan Teb). The resistance level of all E. coli isolates against 10 antibacterial drugs compared statistically in 37 and 43 degrees C using MINITAB Version 14 program. Plasmid DNAs were extracted from each of the E. coli isolates which were grown at 37 and 43 degrees C overnight using alkali lysis method. In this study *lambdaDNA (EcoR1+Hind III digested) was used as marker DNA. According to the results of this study, the resistance rate of E. coli isolates have decreased against trimethoprim-sulfamethazol, lincospectine, tiamaulin, tetracyclin and gentamycin at 43 degrees C but only the difference between the resistance rate against gentamycin in 37 degrees C (83.3%) and 43 degrees C (60%) was significant Characterization of Plasmid DNAs by agarose gel electrophoresis showed that each of the thirty drug resistant E. coli harbored a single plasmid. There was no difference among the plasmid profiles of the thirty isolates in 37 and 43 degrees C. As the plasmid profile did not change in 43 degrees C (heat stress) so the resistance differences against antibacterial drugs were not significant except for gentamycine that its resistance may is chromosomal. According to the results of this study, In conclusion it can be said that heat stress could not be effective on antibacterial resistance and plasmid profile if the duration of the stress is short. The long duration of the heat stress plus other stress factors such as starvation will effect the plasmid replication and finally plasmid copy number of bacteria. Mechanism of this phenomenon remains unknown, though one might speculate that some bacterial addiction modules that are activated upon amino acid starvation, like mazEF could be involved. PMID:19086582

Ahmadi, M; Ayremlou, N; Sale, H Dastmalchi

2007-12-01

246

Electrical and Optical Properties of High-Resistivity Gallium Phosphide  

Microsoft Academic Search

Static and dynamic photoconductive properties of single-crystal high-resistivity (compensated) GaP have been studied in the intrinsic and near infrared spectral region at 300°, 77°, and 27°K. Room-temperature resistivities in excess of 1014 Omega-cm have been produced by copper diffusions into either n- or p-type GaP. Large photoconductivity gains have been measured for intrinsic radiation: Gains in some cases exceeded 104

Bernard Goldstein; S. S. Perlman

1966-01-01

247

Electrical Resistance of Cell Membranes of Avena coleoptiles.  

PubMed

The cell membrane resistance to direct current was measured in single cells for the first time in a higher plant tissue, oat coleoptiles (Avena sativa). On the assumption that the current density over the cell surface was uniform, a mean value of about 1300 ohm-cm(2) was found for cells in an external nutrient medium containing 1 mmole each of K(+), Na(+), and Ca(++) per liter. As expected, either decreasing K(+) concentration or increasing Ca(++) concentration increased the resistance. PMID:17807848

Higinbotham, N; Hope, A B; Findlay, G P

1964-03-27

248

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

NASA Astrophysics Data System (ADS)

A combination 2/4-probe method was used to measure electrical resistances across a pure, monolithic CVD-SiC disc sample with contact resistance at the SiC/metallic electrode interfaces. By comparison of the almost simultaneous 2/4-probe measurements, the specific contact resistance (Rc) and its temperature dependence were determined for two types (sputtered gold and porous nickel) electrodes from room temperature (RT) to ˜973 K. The Rc-values behaved similarly for each type of metallic electrode: Rc > ˜1000 ? cm2 at RT, decreasing continuously to ˜1-10 ? cm2 at 973 K. The temperature dependence of the inverse Rc indicated thermally activated electrical conduction across the SiC/metallic interface with an apparent activation energy of ˜0.3 eV. For the flow channel insert application in a fusion reactor blanket, contact resistance potentially could reduce the transverse electrical conductivity by about 50%.

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

2013-11-01

249

Thickness effect on electric resistivity on polystyrene and carbon black- based composites  

NASA Astrophysics Data System (ADS)

Changes on electrical resistivity were experimentally studied for polystyrene and carbon black-based composites respect to the temperature. 22% w/w carbon black composite films at 30 ?m, 2mm y 1cm thick were submitted to thermal heating-cooling cycles from room temperature to 100°C, slightly up to Tg of the composite. For each cycle changes on electrical resistivity constituent a hysteresis loop that depends on the sample thickness. The changes during the heating stage could be explained as a consequence of the thermal expansion and mobility of the polymer chains at Tg, producing a disconnecting of the electrical contacts among carbon black particles and an important increasing (200%) of the electrical resistivity. For each cycle, the hysteresis loop was observed in thicker samples, whereas for 30 ? m thickness sample the hysteresis loop was lost after four cycles.

Hernández-López, S.; Vigueras-Santiago, E.; Mayorga-Rojas, M.; Reyes-Contreras, D.

2009-05-01

250

DEPENDENCE OF THE ANOMALOUS RESISTIVITY ON THE INDUCED ELECTRIC FIELD IN SOLAR FLARES  

SciTech Connect

Anomalous resistivity is a critical parameter for triggering the fast magnetic reconnection and interpreting the eruption of solar flares in the nearly collisionless coronal plasma. However, the mechanism for the production of anomalous resistivity and its evolution are weakly understood. In this paper, the one-dimensional Vlasov equation was numerically solved with the typical solar coronal parameters and realistic mass ratio in the presence of strong inductive electric field, and the relationship between the anomalous resistivity and the reconnecting electric field was inferred for the area near the center of reconnecting current sheets. Our principal findings are summarized as follows. (1) The relationship between the anomalous resistivity and the reconnecting electric field E {sub 0} may be represented by {eta}{sub eff} = [10.82-10.99 exp (-0.36 E {sub 0})]{Omega} m. (2) If E{sub 0} is small enough, it may be described by {eta}{sub eff} = [4.02 E {sub 0} - 0.18]{Omega} m, which is basically consistent with the early experimental results on the plasma response to the applied electric field. (3) In comparison with theoretical formulas for the current-driven ion-acoustic and Buneman anomalous resistivities, if E{sub 0} is small, the anomalous resistivity may be due to the ion-acoustic instability; if E{sub 0} is large, the anomalous resistivity may be due to the Buneman instability. These results are also basically consistent with early experiments.

Wu Guiping [Department of Physics, Southeast University, Nanjing, Jiangsu 210096 (China); Huang Guangli; Ji Haisheng, E-mail: wuguiping@seu.edu.c, E-mail: glhuang@pmo.ac.c, E-mail: jihs@pmo.ac.c [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, Jiangsu 210008 (China)

2010-09-01

251

Estimation of the junctional resistance between electrically coupled receptor cells in Necturus taste buds  

PubMed Central

Junctional resistance between coupled receptor cells in Necturus taste buds was estimated by modeling the results from single patch pipette voltage clamp studies on lingual slices. The membrane capacitance and input resistance of coupled taste receptor cells were measured to monitor electrical coupling and the results compared with those calculated by a simple model of electrically coupled taste cells. Coupled receptor cells were modeled by two identical receptor cells connected via a junctional resistance. On average, the junctional resistance was approximately 200-300 M omega. This was consistent with the electrophysiological recordings. A junctional resistance of 200-300 M omega is close to the threshold for Lucifer yellow dye-coupling detection (approximately 500 M omega). Therefore, the true extent of coupling in taste buds might be somewhat greater than that predicted from Lucifer yellow dye coupling. Due to the high input resistance of single taste receptor cells (> 1 G omega), a junctional resistance of 200-300 M omega assures a substantial electrical communication between coupled taste cells, suggesting that the electrical activity of coupled cells might be synchronized.

1995-01-01

252

Detection of resistance to imatinib by metabolic profiling: clinical and drug development implications.  

PubMed

Acquired resistance to imatinib mesylate is an increasing and continued challenge in the treatment of BCR-ABL tyrosine kinase positive leukemias as well as gastrointestinal stromal tumors. Stable isotope-based dynamic metabolic profiling (SIDMAP) studies conducted in parallel with the development and clinical testing of imatinib revealed that this targeted drug is most effective in controlling glucose transport, direct glucose oxidation for RNA ribose synthesis in the pentose cycle, as well as de novo long-chain fatty acid synthesis. Thus imatinib deprives transformed cells of the key substrate of macromolecule synthesis, malignant cell proliferation, and growth. Tracer-based magnetic resonance spectroscopy studies revealed a restitution of mitochondrial glucose metabolism and an increased energy state by reversing the Warburg effect, consistent with a subsequent decrease in anaerobic glycolysis. Recent in vitro SIDMAP studies that involved myeloid cells isolated from patients who developed resistance against imatinib indicated that non-oxidative ribose synthesis from glucose and decreased mitochondrial glucose oxidation are reliable metabolic signatures of drug resistance and disease progression. There is also evidence that imatinib-resistant cells utilize alternate substrates for macromolecule synthesis to overcome limited glucose transport controlled by imatinib. The main clinical implications involve early detection of imatinib resistance and the identification of new metabolic enzyme targets with the potential of overcoming drug resistance downstream of the various genetic and BCR-ABL-expression derived mechanisms. Metabolic profiling is an essential tool used to predict, clinically detect, and treat targeted drug resistance. This need arises from the fact that targeted drugs are narrowly conceived against genes and proteins but the metabolic network is inherently complex and flexible to activate alternative macromolecule synthesis pathways that targeted drugs fail to control. PMID:16196499

Serkova, Natalie; Boros, László G

2005-01-01

253

Non-alcoholic fatty liver disease (NAFLD), insulin resistance and lipid profile in antiepileptic drug treatment  

Microsoft Academic Search

PurposePatients undergoing long-term treatment with valproic acid (VPA) are prone to develop different features of the metabolic syndrome (MS). The aim of the present study was to evaluate the occurrence of non-alcoholic fatty liver disease (NAFLD), insulin resistance (IR) and a pro-atherogenic lipid profile in patients undergoing VPA, carbamazepine (CBZ) and lamotrigine (LTG) monotherapy compared to healthy controls.

G. Luef; M. Rauchenzauner; M. Waldmann; W. Sturm; A. Sandhofer; K. Seppi; E. Trinka; I. Unterberger; C. F. Ebenbichler; M. Joannidis; G. Walser; G. Bauer; F. Hoppichler; M. Lechleitner

2009-01-01

254

Electrical resistivity and hydrogen permeation of dip-coated Er2O3 on JLF-1  

NASA Astrophysics Data System (ADS)

Liquid blanket systems are very promising directions for future fusion reactors. A ceramic coating on the ducts would solve issues for the liquid blankets such as MHD pressure drop and tritium permeation through structure materials. In this study, an Er2O3 coating was fabricated on JLF-1 (Fe-9Cr-2W based reduced activation ferritic/martensitic steel), SUS430 (18Cr based commercial ferritic steel) by dip-coating method with metal organic decomposition (MOD) liquid followed by baking in air. XRD patterns indicated that good crystallinity of the Er2O3 coating was obtained for the baking temperature of 600 °C. The highest electrical resistivity was about 1011 ? m. Below the coating, a substrate oxidation layer was also formed according to a XPS elemental depth profile. Hydrogen permeability of the coated sample was decreased only by 1/15 compared with bare JLF-1 sample. The reason might be oxidation of the substrate surface for degrading the coating barrier performance.

Zhang, Dongxun; Tanaka, Teruya; Muroga, Takeo

2011-10-01

255

Determining concentration depth profiles in fluorinated networks by means of electric force microscopy  

SciTech Connect

By means of electric force microscopy, composition depth profiles were measured with nanometric resolution for a series of fluorinated networks. By mapping the dielectric permittivity along a line going from the surface to the bulk, we were able to experimentally access to the fluorine concentration profile. Obtained data show composition gradient lengths ranging from 30 nm to 80 nm in the near surface area for samples containing from 0.5 to 5 wt. % F, respectively. In contrast, no gradients of concentration were detected in bulk. This method has several advantages over other techniques because it allows profiling directly on a sectional cut of the sample. By combining the obtained results with x-ray photoelectron spectroscopy measurements, we were also able to quantify F/C ratio as a function of depth with nanoscale resolution.

Miccio, Luis A. [Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), JB. Justo 4302, Mar del Plata, Buenos Aires (Argentina); Centro de Fisica de Materiales CSIC-UPV/EHU, Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastian (Spain); Kummali, Mohammed M.; Alegria, Angel [Centro de Fisica de Materiales CSIC-UPV/EHU, Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales UPV/EHU, Facultad de Quimica, 20080 San Sebastian (Spain); Montemartini, Pablo E.; Oyanguren, Patricia A. [Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), JB. Justo 4302, Mar del Plata, Buenos Aires (Argentina); Schwartz, Gustavo A. [Centro de Fisica de Materiales CSIC-UPV/EHU, Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastian (Spain); Colmenero, Juan [Centro de Fisica de Materiales CSIC-UPV/EHU, Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales UPV/EHU, Facultad de Quimica, 20080 San Sebastian (Spain); Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian (Spain)

2011-08-14

256

The competing impacts of geology and groundwater on electrical resistivity around Wrightsville Beach, NC  

NASA Astrophysics Data System (ADS)

Measurements of electrical resistivity have long been used to find freshwater resources below the earth's surface. Recently, offshore resistivity and electromagnetic techniques have been used to map occurrences of submarine groundwater originating from the offshore extension of terrestrial aquifers. In many cases, observations of a high resistivity (low conductivity) anomaly in the seafloor are sufficient to suggest the presence of fresh (and less conductive) pore waters. Data from offshore Wrightsville Beach, NC show highly variable resistivity structure, with moderately high resistivity at depths of ˜20 m subsurface that is at least in part caused by lithologic complexity in an underlying limestone unit, the Castle Hayne. These offshore results suggest caution in the interpretation of resistivity anomalies simply in terms of groundwater volumes. In contrast, low onshore resistivities show evidence for intrusion of saltwater into the subsurface beneath the beach, adjacent to areas of pumping for water supply.

Evans, Rob. L.; Lizarralde, Dan

2011-05-01

257

Emergence of pulsed electric fields resistance in Salmonella enterica serovar Typhimurium SL1344.  

PubMed

In this investigation we selected and isolated a culture derived from Salmonella enterica serovar Typhimurium SL1344 with stable increased resistance to pulsed electric fields (PEF) after repeated rounds of PEF treatment and outgrowth of survivors. The resulting culture showed a higher resistance to PEF treatments under different treatment conditions. The acquisition of PEF resistance was only observed in stationary phase cells. The cytoplasmic membrane of the resistant variant showed a higher resilience against PEF treatments, since a lower permeabilization degree was observed after PEF treatments, in comparison to the parental strain. Resistance to PEF was also accompanied by a higher tolerance to acidic pH, hydrogen peroxide and ethanol, but not to heat. The occurrence of a PEF resistant variant in S. enterica serovar Typhimurium SL1344 emphasizes the need to further study the mechanisms of inactivation and resistance by PEF for an adequate design of safe treatments. PMID:23973831

Sagarzazu, N; Cebrián, G; Pagán, R; Condón, S; Mañas, P

2013-07-12

258

Digital photogrammetric analysis and electrical resistivity tomography for investigating the Picerno landslide (Basilicata region, southern Italy)  

NASA Astrophysics Data System (ADS)

Digital photogrammetric analysis and Electrical Resistivity Tomography (ERT) techniques were applied to evaluate the volume of material involved in a complex roto-translational slide occurred in the territory of Picerno (Basilicata region, southern Italy). Analytical and digital photogrammetric techniques facilitated a multi-temporal analysis of aerial photos for the years 1997, 2004 and 2006. In order to identify different geomorphologic features (scarps, terraces and trenches) of the landslide and their development, the analytical and digital photo interpretation was performed at the maximum scale of 1:5000. Geological and geomorphological surveys were carried out to verify photo-interpretation results. Digital Elevation Models (DEMs) for 1997, 2004 and 2006 were produced by applying the Grid Adaptive method. The differential DEMs (2006-1997; 2006-2004; 2004-1997) for the most dangerous part of the landslide allowed us to recognize the areas affected either by deposition or erosion and also estimate any altitudinal changes in each geomorphologic unit. To detect the sliding surface and estimate the thickness of the sliding material, several transversal and longitudinal ERT profiles were obtained. The electrical images of subsurface supported by stratigraphical data from boreholes were integrated with the information from the DEMs. The altitudinal changes and the sizes of the source and accumulation areas allowed us to estimate the volume of material involved in the mass movement. The fusion of data from different sensors allows us to gather indications on the surface and subsurface characteristics of the landslide providing useful information for landslide mitigation activities. Such an approach can help both to improve our knowledge and overcome the drawbacks of each methodology.

de Bari, Claudia; Lapenna, Vincenzo; Perrone, Angela; Puglisi, Claudio; Sdao, Francesco

2011-10-01

259

Soil properties, GPS, arcview, and soil resistivity provide tools for protecting electrical equipment from lightning and heat  

Microsoft Academic Search

Resistivity measurements determine the number of chemically enhanced grounding rods needed to provide protection from lightning strikes and mechanical heating of electrical equipment. Soil physical properties such as texture, rock content, soil thickness, and water content determine resistivity and grounding potential. A study was initiated to (1) establish a database of electrical resistivity properties for several soil series in southwest

Jamie Burr; Harry James; Christopher Hamon

2000-01-01

260

Screening of Chemical Penetration Enhancers for Transdermal Drug Delivery Using Electrical Resistance of Skin  

Microsoft Academic Search

Purpose  A novel technique is presented for identifying potential chemical penetration enhancers (CPEs) based on changes in the electrical\\u000a resistance of skin.\\u000a \\u000a \\u000a \\u000a Methods  Specifically, a multi-well resistance chamber was designed and constructed to facilitate more rapid determination of the effect\\u000a of CPEs on skin resistance. The experimental setup was validated using nicotine and decanol on porcine skin in vitro. The multi-well resistance

Vijay Krishna Rachakonda; Krishna Mohan Yerramsetty; Sundararajan V. Madihally; Robert L. Robinson; Khaled A. M. Gasem

2008-01-01

261

Time-lapse electrical resistivity tomography: a powerful tool for landslide monitoring?  

NASA Astrophysics Data System (ADS)

The extreme rainfall events and the quick snowmelt occurrences play an important role in the triggering of the landslides. The occurrence of one of these factors can determine the variation of water content in the first layers of the subsoil and as a consequence a quick soil saturation inducing both an increase in pore-water pressures and the overloaded of the slopes progressively collapsing. The electrical resistivity, self-potential, electromagnetic induction and GPR methods can be considered as the most appropriate for assessing the presence of water in the underground. Such methods allow us to study the behavior of water content over much wider and deeper areas than those offered by traditional methods (thermo-gravimetric, tensiometric, TDR, etc) based on spot measures and concerning small volumes. In particular, the Electrical Resistivity Tomography (ERT), which has already proved to be a powerful tool both for the geometrical reconstruction of a landslide body (location of sliding surface, estimation of the thickness of the slide material) and the individuation of high water content areas, can be considered as an alternative tool to be employed for a qualitative and quantitative water content monitoring in the first layers of the subsoil. Indeed, time-lapse 2D ERT can be tested in order to gather information on the temporal and spatial patterns of water infiltration processes and water content variation. This work reports the preliminary results from a new prototype system planned to obtain time-lapse 2D ERTs, TDR and precipitation measurements in two landslide areas located in the Southern Apennine chain (Italy). The system was planned with the aim to estimate the variation of the resistivity parameter on a long period considering the water content variation, the rain water infiltration and the seasonal changes. The prototype system, linked to a pc used for storing data and managing the time interval acquisition, consists of: a resistivimeter connected to a multichannel cable, 48 steel electrodes buried in the soil at a depth of about 0.5 m at a distance of 1 or 5 m; a TDR system linked to 4 probes 20 cm length, buried at different depths along the same profile of the geoelectrical one; while a weather station consists of a rain gauge to quantify the amount of rain falling on that area, one sensor to measure the temperature and another to determine the speed and direction of the wind. At the beginning the time-lapse ERT were analysed to verify the functionality and stability of the system and to decide the measurement time intervals. After that, the statistical analysis of the results obtained was performed with the aim to define the water content variation in the first layers of the subsoil, in particular in the vadose zone. The results were compared with the TDR ones and the piezometric measurements were performed in the area thanks to the presence of equipped boreholes. The correlation between the variation of the parameters measured (electrical resistivity, water content and piezometric level) and the rain-gauge measurements was also considered. The preliminary results seem to be encouraged also if the analysis of the data acquired on a longer period could better highlight the capability of the system.

Perrone, A.

2011-12-01

262

Positive and negative differential resistance in electrical conductors  

Microsoft Academic Search

A phase transition from one conducting state to another and the appearance of positive and negative differential resistance in the current-voltage characteristic is investigated experimentally for the gap instability in nonequilibrium superconductors and the avalanche breakdown in extrinsic semiconductors. Additional observation of spatial current structures in the transition regime of both solid-state systems stimulates a simple model approach connecting these

J. Peinke; D. B. Schmid; B. Röhricht; J. Parisi

1987-01-01

263

Fatigue Resistant Muscle by Cell Transplantation and Electrical Conditioning  

Microsoft Academic Search

Congestive heart failure refractory to medical therapy can be managed with cardiac trans- plantation or artificial heart. Due to the scarcity of donor organs and unsatisfactory long- term outcomes of mechanical devices, skeletal muscle has been used to augment circulatory function. Dynamic cardiomyoplasty, skeletal muscle ventricle, aortomyoplasty, and muscle powered assist devices all require the fatigue resistant muscle to support

Race L. Kao; Janet Davis; Elizabeth Lamb; William Browder

264

Antimicrobial resistance profiles of dairy and clinical isolates and type strains of enterococci.  

PubMed

The susceptibility to 30 antimicrobial agents was determined by the disk diffusion method for a collection of 172 enterococcal strains, including 96 isolates from dairy sources, 50 isolates of human and veterinary origin, and 26 reference strains from 24 different enterococcal species. Results were analysed by hierarchic numerical methods to cluster strains and to group antimicrobials according to similarity profiles. Resistance to 17 of the 30 antimicrobials showed to be correlated, leading to four groups reflecting the mode of action: quinolones (ofloxacin, enrofloxacin, ciprofloxacin and norfloxacin); macrolides (erythromycin, spiramycin), phenicols (cloramphenicol) and tetracyclins (tetracycline, oxytetracyclin); aminoglycosides (gentamicin, kanamycin) and lincosamides (clindamycin); penicillins (amoxicillin, ampicillin, penicillin G, piperacillin) and carbapenems (imipenem). Overall, the genus Enterococcus behaved as resistant to lincomycin, colistin, polimixin B and, with a few exceptions in dairy isolates, to methicillin. In general, all isolates were susceptible to vancomycin, cloramphenicol and fusidic acid. Clusters containing only dairy isolates were susceptible to the majority of antimicrobials tested, as opposed to clusters constituted only by clinical enterococcal isolates. Among the clinical isolates, 62% were highly multiresistant. Low level gentamicin resistance was found to be associated with clinical enterococci. Among dairy isolates, those that clustered with clinical isolates were both resistant to gentamicin and identified as Enterococcus faecalis. Resistance to macrolides, quinolones, penicillins and imipenem was found to be associated also with clinical environments, mainly with multiresistant isolates, contrary to what is generally agreed as a characteristic of the genus. Veterinary clinical isolates were mainly grouped with the multiresistant clinical human isolates. The 26 reference enterococcal strains were distributed in clusters with different antibiotic resistance profiles and were mainly clustered with dairy isolates. PMID:16083821

de Fátima Silva Lopes, Maria; Ribeiro, Tânia; Abrantes, Marta; Figueiredo Marques, José Joaquim; Tenreiro, Rogério; Crespo, Maria Teresa Barreto

2005-08-25

265

[Numerical simulation and application of electrical resistivity survey in heavy metal contaminated sites].  

PubMed

In order to analyze the effects of electrical resistivity in heavy metal contaminated sites, we established the resistivity model of typical contaminated sites and simulate the DC resistivity method with Wenner arrays using the finite element method. The simulation results showed that the electrical method was influenced by the contamination concentration and the location of pollution. The more serious the degree of pollution was, the more obvious the low resistivity anomaly, thus the easier the identification of the contaminated area; otherwise, if there was light pollution, Wenner array could not get obvious low resistivity anomalies, so it would be hard to judge the contaminated area. Our simulation results also showed that the closer the contaminated areas were to the surface, the more easily the pollution was detected and the low resistivity anomalies shown in the apparent resistivity diagram were influenced by the Layered medium. The actual field survey results using resistivity method also show that the resistivity method can correctly detect the area with serious pollution. PMID:23914547

Wang, Yu-ling; Nai, Chang-xin; Wang, Yan-wen; Dong, Lu

2013-05-01

266

Spitzer or neoclassical resistivity: A comparison between measured and model poloidal field profiles on PBX-M  

SciTech Connect

Direct measurements of the radial profile of the magnetic field line pitch on PBX-M coupled with model predictions of these profiles allow a critical comparison with the Spitzer and neoclassical models of plasma parallel resistivity. The measurements of the magnetic field line pitch are made by Motional Stark Effect polarimetry, while the model profiles are determined by solving the poloidal field diffusion equation in the TRANSP transport code using measured plasma profiles and assuming either Spitzer or neoclassical resistivity. The measured field pitch profiles were available for only seven cases, and the model profiles were distinguishable from each other in only three of those cases due to finite resistive diffusion times. The data in two of these three were best matched by the Spitzer model, especially in the inner half of the plasma. Portions of the measured pitch profiles for these two cases and the full profiles for other cases, however, departed significantly from both the Spitzer and neoclassical models, indicating a plasma resistivity profile different from either model.

Kaye, S.M.; Hatcher, R.; Kaita, R.; Kessel, C.; LeBlanc, B.; McCune, D.C.; Paul, S. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Levinton, F.M. [Fusion Physics and Technologies, Torrance, CA (United States)

1992-01-01

267

Strategies of ARP application (Automatic Resistivity Profiling) for viticultural precision farming  

NASA Astrophysics Data System (ADS)

Introduction Viticultural precision farming needs detailed soil information, which can be obtained by means of remote as well as proximal sensors, besides traditional invasive soil survey. Nevertheless, the use of the new technologies is still in its infancy, because of their costs and the lack of knowledge about the detail actually needed for the viticultural husbandry. The main aim of this work was to test the sensitivity of the ARP methodology (Automatic Resistivity Profiling) in supporting soil survey for viticultural precision farming. In addition, we tried to optimize the detail of geoelectrical measurements and soil sampling to reduce the cost of the integrated survey, maintaining a significant information accuracy for viticulture. Materials and methods Two vineyards in coastal Tuscany (central Italy), about 3.5 ha each, were selected. Vineyard 1 was cultivated with Cabernet Sauvignon and Cabernet Franc, while vineyard 2 only had Cabernet Sauvignon. Soil survey and geoelectrical investigation were conducted in may 2007. The ARP methodology consists in the injection in soil of electric current through one pair of electrodes mounted on teeth wheels and measuring the resulting potential with other three pairs of electrodes, placed of the same mobile equipment. The electrical resistance of the soil (ER) is expressed as ohm per m. The depth of investigation is a function of the geometry of the electrodes and the soil being probed. Increasing the distance between electrodes will increase the depth while decreasing the measured potential. The innovative character of the ARP technique is represented by the passage of a mobile machinery, able to perform 30,000 measurements per hectare, with a measurement every 0.2 m. The ARP system, equipped with a digital encoder and DGPS system, is transported by a four-wheeled vehicle. It is fitted with three sensors that contemporaneously analyse three distinct levels of the soil, the values of which are represented by maps of apparent resistivity, from the surface to 0.5 m, 1 m and 1.7 m depth respectively. Soil sampling at 0.1-0.3 m and 0.5-0.7 m was carried out with hand auger on a regular grid sampling scheme (35-40 m per 20 m). Soil samples were analysed for moisture, particle size, and electrical conductivity in water. The spatial viticultural behaviour was appreciated in both vineyards through image analysis of aerial photographs and, in vineyard 2, by means of a grape sampling and analysis of the must at harvest. The vines chosen for the sampling were selected according to the results of the geoelectrical survey. Results and discussion Laboratory analysis showed that the most frequent texture class in both vineyards was clay loam, followed by clay. ER spatial variability however was different in the two vineyards. In vineyard 1, the occurrence of low ER values at 0-0.5 and 0-1 m depths correlated with the presence of clayey and saline soil horizons. In vineyard 2, only ER at 0-1 m depth correlated with clay and soil water content. In vineyard 1, the relationship between ER and clay content allowed the evaluation of the loss of accuracy caused by the reduction of the number of analysed soil samples. Passing from the initial 51 samples, to 25, 12, and 6, the accuracy in clay prediction passed from 100% to 79.4, 79.1, and 74%, respectively. The reduction of accuracy of ER prediction at less intense surveys, was limited, in spite of the relatively high soil variability. In fact, doubling the distance between the passages of the machinery between the vine rows, the accuracy of ER prediction was still of 74%, and even widening it at 24 m, from the initial 6 m, the accuracy remained 64%. The density of vegetation in vineyard 1 was positively correlated with ER, while it was inverse in vineyard 2. The opposite behaviour was due to the soil salinity of vineyard 1, which inversely correlated with ER and vegetation vigour. In vineyard 2, on the other hand, the lack of soil salinity enhanced the relationship between vine vigour and water content. In the same vineyard, the sugar content of

Costantini, E. A. C.; Andrenelli, M. C.; Bucelli, P.; Magini, S.; Natarelli, L.; Pellegrini, S.; Perria, R.; Storchi, P.; Vignozzi, N.

2009-04-01

268

Thickness dependent electrical resistivity of ultrathin (<40 nm) Cu films  

Microsoft Academic Search

Ultrathin Cu films with thicknesses d between ?10 and 40 nm were thermally evaporated onto ?500-nm thick SiO2 on Si(100) substrates in an ultra high vacuum (UHV) chamber with a base pressure of 5×10?10 torr. The sheet resistance R (?\\/?), was measured in situ at different film thicknesses by a collinear four-point probe. The infinite R at d<10 nm suggested

H.-D Liu; Y.-P Zhao; G Ramanath; S. P Murarka; G.-C Wang

2001-01-01

269

The Concept of Electrical Resistance: How Cassirer's Philosophy, and the Early Developments of Electric Circuit Theory, Allow a Better Understanding of Students' Learning Difficulties.  

ERIC Educational Resources Information Center

|Investigates the difficulties students are confronted with when facing the concept of electrical resistance. Discusses the nature of the electrical resistance concept in light of Cassirer philosophy and its origin in the 19th century. Presents an analysis of the way this concept is taught in French high schools. (SAH)|

Viard, Jerome; Khantine-Langlois, Francoise

2001-01-01

270

Fabrication of intermetallic coatings for electrical and corrosion resistance on high-temperature alloys  

SciTech Connect

Several intermetallic films were fabricated to high-temperature alloys (V-alloys and 304 and 316 stainless steels) to provide electrical insulation and corrosion resistance. Alloy grain-growth behavior at 1000{degrees}C for the V-5Cr-5Ti was investigated to determine the stability of alloy substrate during coating formation by chemical vapor deposition (CVD) or metallic vapor processes at 800-850{degrees}C. Film layers were examined by optical and scanning electron microscopy and by electron-energy-dispersive and X-ray diffraction analysis and tested for electrical resistivity and corrosion resistance. The results elucidated the nature of the coatings, which provided both electrical insulation and high-temperature corrosion protection.

Park, J.H. [Argonne National Lab., IL (United States); Cho, W.D. [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Metallurgical Engineering

1994-10-01

271

Electrical Resistivity of Laves Phase Compounds Containing Transition Elements. II. Co2A (A=Ti, Y, Zr, and Nb)  

Microsoft Academic Search

The electrical resistivity of a series of Co2A Laves phase compounds was measured in order to investigate its mutual correlation with their magnetic properties. In the weakly Pauli-paramagnetic compounds, Co2Ti, Co2Zr and Co2Nb, the electrical resistivity shows a temperature variation proportional to T3 below about 30 K. The electrical resistivity of the strongly Pauli-paramagnetic Co2Y compound shows a fairly large

Koki Ikeda

1977-01-01

272

Electrical resistivity of thermally evaporated bismuth telluride thin films  

Microsoft Academic Search

Semiconducting chalcogenide thin films have been receiving considerable attention in the recent years because of their wide applications in the various fields of science and technology. The studies of the electronic properties of semiconductors have been largely stimulated by attractive micro-electronic device applications. Among the various V–VI compounds, Bismuth Telluride (Bi2Te3) is an established low-temperature thermo electric material and is

J. Dheepa; R. Sathyamoorthy; S. Velumani; A. Subbarayan; K. Natarajan; P. J. Sebastian

2004-01-01

273

Influence of gamma -Irradiation on the Electrical Resistance of Yttrium Dopped BaTiO sub 3.  

National Technical Information Service (NTIS)

The behaviour of electrical resistance of irradiated yttrium dopped BaTiO sub 3 thermistors with positive temperature coefficient of resistance as a function of temperature is investigated. Calculations of the shift of the Curie transition temperature due...

I. Bunget A. Ludu M. Ludu P. Nicolau

1984-01-01

274

Transcriptional Profiles Uncover Aspergillus flavus-Induced Resistance in Maize Kernels  

PubMed Central

Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and through storage. Previous studies have highlighted the constitutive production of proteins involved in maize kernel resistance against A. flavus’ infection. However, little is known about induced resistance nor about defense gene expression and regulation in kernels. In this study, maize oligonucleotide arrays and a pair of closely-related maize lines varying in aflatoxin accumulation were used to reveal the gene expression network in imbibed mature kernels in response to A. flavus’ challenge. Inoculated kernels were incubated 72 h via the laboratory-based Kernel Screening Assay (KSA), which highlights kernel responses to fungal challenge. Gene expression profiling detected 6955 genes in resistant and 6565 genes in susceptible controls; 214 genes induced in resistant and 2159 genes induced in susceptible inoculated kernels. Defense related and regulation related genes were identified in both treatments. Comparisons between the resistant and susceptible lines indicate differences in the gene expression network which may enhance our understanding of the maize-A. flavus interaction.

Luo, Meng; Brown, Robert L.; Chen, Zhi-Yuan; Menkir, Abebe; Yu, Jiujiang; Bhatnagar, Deepak

2011-01-01

275

Evolution of low-profile and lightweight electrical connectors for soldier-worn applications  

NASA Astrophysics Data System (ADS)

In addition to military radios, modern warfighters carry cell phones, GPS devices, computers, and night-vision aids, all of which require electrical cables and connectors for data and power transmission. Currently each electrical device operates via independent cables using conventional cable and connector technology. Conventional cables are stiff and difficult to integrate into a soldier-worn garment. Conventional connectors are tall and heavy, as they were designed to ensure secure connections to bulkhead-type panels, and being tall, represent significant snag-hazards in soldier-worn applications. Physical Optics Corporation has designed a new, lightweight and low-profile electrical connector that is more suitable for body-worn applications and operates much like a standard garment snap. When these connectors are mated, the combined height is <0.3 in. - a significant reduction from the 2.5 in. average height of conventional connectors. Electrical connections can be made with one hand (gloved or bare) and blindly (without looking). Furthermore, POC's connectors are integrated into systems that distribute data or power from a central location on the soldier's vest, reducing the length and weight of the cables necessary to interconnect various mission-critical electronic systems. The result is a lightweight power/data distribution system offering significant advantages over conventional electrical connectors in soldier-worn applications.

Gans, Eric; Lee, Kang; Jannson, Tomasz; Walter, Kevin

2011-05-01

276

Measurement of Melting Point, Normal Spectral Emittance (at Melting Point) and Electrical Resistivity (near Melting Point) of Some Refractory Alloys.  

National Technical Information Service (NTIS)

A subsecond duration pulse heating method is used to measure the melting point, normal spectral emittance (at the melting point, corresponding to 650 nm), and electrical resistivity (near the melting point, corresponding to 650 nm), and electrical resisti...

A. Cezairliyan

1973-01-01

277

In situ electrical resistance and activation energy of solid C60 under high pressure  

NASA Astrophysics Data System (ADS)

The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil cell. In the experiment, four parts of boron-doped diamond films fabricated on one anvil were used as electrical measurement probes and a W—Ta thin film thermocouple which was integrated on the other diamond anvil was used to measure the temperature. The current results indicate that the measured high-pressure resistances are bigger than those reported before at the same pressure and there is no pressure-independent resistance increase before 8 GPa. From the temperature dependence of the resistivity, the C60 behaviors as a semiconductor and the activation energies of the cubic C60 fullerene are 0.49, 0.43, and 0.36 eV at 13, 15, and 19 GPa, respectively.

Yang, Jie; Liu, Cai-Long; Gao, Chun-Xiao

2013-09-01

278

Cryostat for simultaneous investigation of thermal conductivity, electrical resistivity and thermoelectric power in the process of low temperature tensile deformation  

Microsoft Academic Search

A cryostat for simultaneous measuring of thermal conductivity, electrical resistivity and thermoelectric power of metals and alloys in the presence of low temperature tensile deformation is described.

P G Vassilev; J K Georgiev

1970-01-01

279

Impact of terminal dimethylation on the resistance profile of ?-N-heterocyclic thiosemicarbazones.  

PubMed

Triapine is an ?-N-heterocyclic thiosemicarbazone with promising anticancer activity against hematologic malignancies but widely ineffective against solid tumor types in clinical trials. The anticancer activity of thiosemicarbazones can be dramatically increased by terminal dimethylation. KP1089 is a gallium compound containing two terminal dimethylated thiosemicarbazone ligands. To gain insights on the vulnerability of this highly active terminal dimethylated thiosemicarbazone to drug resistance mechanisms, a new cell model with acquired resistance against the lead compound KP1089 was established. Subsequent genomic analyses (arrayCGH and FISH) revealed amplification of the ABCC1 gene on double minute chromosomal DNA in KP1089-resistant cells as well as overexpression of ABCC1 and ABCG2 on the protein level. KP1089 was further confirmed as a substrate of ABCC1 and ABCG2 but not of ABCB1 using a panel of ABC transporter-overexpressing cell models as well as ABC transporter inhibitors. Moreover, glutathione depletion strongly enhanced KP1089 activity, although no glutathione conjugate formation by glutathione-S-transferase was observed. Thus, a co-transport of KP1089 together with glutathione is suggested. Finally, a panel of thiosemicarbazone derivatives was tested on the new KP1089-resistant cell line. Notably, KP1089-resistant cells were not cross-resistant against thiosemicarbazones lacking terminal dimethylation (e.g. Triapine) which are less active than KP1089. This suggests that terminal dimethylation of thiosemicarbazones - linked with distinctly enhanced anticancer activity - leads to altered resistance profiles compared to classical thiosemicarbazones making this compound class of interest for further (pre)clinical evaluation. PMID:22426010

Heffeter, Petra; Pirker, Christine; Kowol, Christian R; Herrman, Gerrit; Dornetshuber, Rita; Miklos, Walter; Jungwirth, Ute; Koellensperger, Gunda; Keppler, Bernhard K; Berger, Walter

2012-03-15

280

Impact of terminal dimethylation on the resistance profile of ?-N-heterocyclic thiosemicarbazones  

PubMed Central

Triapine is an ?-N-heterocyclic thiosemicarbazone with promising anticancer activity against hematologic malignancies but widely ineffective against solid tumor types in clinical trials. The anticancer activity of thiosemicarbazones can be dramatically increased by terminal dimethylation. KP1089 is a gallium compound containing two terminal dimethylated thiosemicarbazone ligands. To gain insights on the vulnerability of this highly active terminal dimethylated thiosemicarbazone to drug resistance mechanisms, a new cell model with acquired resistance against the lead compound KP1089 was established. Subsequent genomic analyses (arrayCGH and FISH) revealed amplification of the ABCC1 gene on double minute chromosomal DNA in KP1089-resistant cells as well as overexpression of ABCC1 and ABCG2 on the protein level. KP1089 was further confirmed as a substrate of ABCC1 and ABCG2 but not of ABCB1 using a panel of ABC transporter-overexpressing cell models as well as ABC transporter inhibitors. Moreover, glutathione depletion strongly enhanced KP1089 activity, although no glutathione conjugate formation by glutathione-S-transferase was observed. Thus, a co-transport of KP1089 together with glutathione is suggested. Finally, a panel of thiosemicarbazone derivatives was tested on the new KP1089-resistant cell line. Notably, KP1089-resistant cells were not cross-resistant against thiosemicarbazones lacking terminal dimethylation (e.g. Triapine) which are less active than KP1089. This suggests that terminal dimethylation of thiosemicarbazones – linked with distinctly enhanced anticancer activity – leads to altered resistance profiles compared to classical thiosemicarbazones making this compound class of interest for further (pre)clinical evaluation.

Heffeter, Petra; Pirker, Christine; Kowol, Christian R.; Herrman, Gerrit; Dornetshuber, Rita; Miklos, Walter; Jungwirth, Ute; Koellensperger, Gunda; Keppler, Bernhard K.; Berger, Walter

2012-01-01

281

Method for producing low-resistivity electrical contacts for high-temperature superconducting ceramics  

DOEpatents

Production of low-resistivity electrical contacts for high-temperature superconducting ceramics capable of supporting large current densities by plasma spraying of a noble metal powder onto a chosen surface area of the ceramic and electrically contacting a metal conductor to the metallic pad formed thereby by either soldering or by use of a conducting epoxy is described. Surface resistivities in the 10{sup {minus}8} {Omega}-cm{sup 2} range have been measured at 76 K. Most experimental variables were found to have little effect on the properties of the contacts produced. 2 tabs.

Katz, J.D.; Willis, J.O.; Maley, M.P.; Castro, R.G.

1989-08-22

282

Low electrical resistivity carbon nanotube and polyethylene nanocomposites for aerospace and energy exploration applications  

NASA Astrophysics Data System (ADS)

An investigation was conducted towards the development and optimization of low electrical resistivity carbon nanotube (CNT) and thermoplastic composites as potential materials for future wire and cable applications in aerospace and energy exploration. Fundamental properties of the polymer, medium density polyethylene (MDPE), such as crystallinity were studied and improved for composite use. A parallel effort was undertaken on a broad selection of CNT, including single wall, double wall and multi wall carbon nanotubes, and included research of material aspects relevant to composite application and low resistivity such as purity, diameter and chirality. With an emphasis on scalability, manufacturing and purification methods were developed, and a solvent-based composite fabrication method was optimized. CNT MDPE composites were characterized via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman spectroscopy, and multiple routes of electron microscopy. Techniques including annealing and pressure treatments were used to further improve the composites' resulting electrical performance. Enhancement of conductivity was explored via exposure to a focused microwave beam. A novel doping method was developed using antimony pentafluoride (SbF5) to reduce the resistivity of the bulk CNT. Flexible composites, malleable under heat and pressure, were produced with exceptional electrical resistivities reaching as low as 2*10-6O·m (5*105S/m). A unique gas sensor application utilizing the unique electrical resistivities of the produced CNT-MDPE composites was developed. The materials proved suitable as a low weight and low energy sensing material for dimethyl methylphosphonate (DMMP), a nerve gas simulant.

Moloney, Padraig G.

283

Risk analysis and detection of thrombosis by measurement of electrical resistivity of blood.  

PubMed

Monitoring of thrombogenic process is very important in ventricular assistance devices (VADs) used as temporary or permanent measures in patients with advanced heart failure. Currently, there is a lack of a system which can perform a real-time monitoring of thrombogenic activity. Electrical signals vary according to the change in concentration of coagulation factors as well as the distribution of blood cells, and thus have potential to detect the thrombogenic process in an early stage. In the present work, we have made an assessment of an instrumentation system exploiting the electrical properties of blood. The experiments were conducted using bovine blood. Electrical resistance tomography with eight-electrode sensor was used to monitor the spatio-temporal change in electrical resistivity of blood in thrombogenic and non-thrombogenic condition. Under non-thrombogenic condition, the resistivity was uniform across the cross-section and average resistivity monotonically decreased with time before remaining almost flat. In contrary, under thrombogenic condition, there was non-uniform distribution across the cross-section, and average resistivity fluctuated with time. PMID:24110630

Sapkota, Achyut; Asakura, Yuta; Maruyama, Osamu; Kosaka, Ryo; Yamane, Takashi; Takei, Masahiro

2013-07-01

284

High pressure electrical resistivity studies on Ni-doped TiO 2 nanoparticles  

Microsoft Academic Search

Electrical resistivity measurement of Ni-doped TiO2 nanoparticles were performed under high pressure using a Bridgman opposed anvil setup. It is observed that, anatase phase nanoparticles shows a sudden increase in resistivity below the pressure limit of 4GPa and is attributed to the transition from anatase to rutile phase. In addition, the transition limit is shifted towards lower pressure region with

K. Karthik; N. Victor Jaya

2011-01-01

285

Aquatic electrical resistivity imaging of rainfall-driven solute transport in contaminated wetlands  

Microsoft Academic Search

A continuous aquatic electrical resistivity imaging (ERI) technique, using floating electrodes and a shallow-draft paddleboat, was employed to predict spatial and temporal patterns of pore-fluid conductivity in wetland soils of a contaminated, shallow-water wetland. ERI measurements were obtained with marine-acquisition software and a multi-channel resistivity instrument at six times over a four month period, covering a 10 square kilometer grid.

L. Slater; N. Mansoor

2007-01-01

286

Transients of Resistance-Terminated Dissipative Low-Pass and High-Pass Electric Wave Filters  

Microsoft Academic Search

Formulas are derived for the solution of the transient receiving-end currents of resistance-terminated dissipative T- and ?-type low-pass and high-pass electric wave filters. Oscillograms taken with a cathode-ray oscillograph for direct- and alternating-current cases are found to agree with the results calculated from these formulas. From these calculations the following conclusions are derived: (1) When the terminating resistance is gradually

W. Chu; Chung-Kwei Chang

1938-01-01

287

Stable hole doping of graphene for low electrical resistance and high optical transparency  

Microsoft Academic Search

We report on the p doping of graphene with the polymer TFSA ((CF3SO2)2NH). Modification of graphene with TFSA decreases the graphene sheet resistance by 70%. Through such modification, we report sheet resistance values as low as 129 Omega, thus attaining values comparable to those of indium-tin oxide (ITO), while displaying superior environmental stability and preserving electrical properties over extended time

S. Tongay; K. Berke; M. Lemaitre; Z. Nasrollahi; D. B. Tanner; A. F. Hebard; B. R. Appleton

2011-01-01

288

On the fatigue life prediction of CFRP laminates using the Electrical Resistance Change method  

Microsoft Academic Search

The electro-mechanical response (Electrical Resistance Change method) as a damage index of quasi-isotropic Carbon Fiber Reinforced (CFRPs) laminates under fatigue loading was investigated. The effect of dispersed Multi-Wall Carbon Nanotubes (MWCNT) into the epoxy matrix was additionally evaluated and compared with neat epoxy CFRPs. The longitudinal resistance change of the specimens was monitored throughout the fatigue experiment. Three different stress

A. Vavouliotis; A. Paipetis; V. Kostopoulos

2011-01-01

289

Universal electric-field-driven resistive transition in narrow-gap Mott insulators.  

PubMed

A striking universality in the electric-field-driven resistive switching is shown in three prototypical narrow-gap Mott systems. This model, based on key theoretical features of the Mott phenomenon, reproduces the general behavior of this resistive switching and demonstrates that it can be associated with a dynamically directed avalanche. This model predicts non-trivial accumulation and relaxation times that are verified experimentally. PMID:23649904

Stoliar, Pablo; Cario, Laurent; Janod, Etiene; Corraze, Benoit; Guillot-Deudon, Catherine; Salmon-Bourmand, Sabrina; Guiot, Vincent; Tranchant, Julien; Rozenberg, Marcelo

2013-05-06

290

Load rates of low voltage transformers and medium voltage profile assessments on a real distribution electric grid based on average Daily Load Profile (DLP) of a housing for a high penetration of plug-in hybrid electric vehicles (PHEVs)  

Microsoft Academic Search

This paper assesses the impact of PHEVs on a real medium voltage distribution electric grid based on average Daily Loads Profiles (DLPs) of a PHEV and of a housing. For three penetration rates, we show the important effects on load rates of low voltage transformers which compose the studied urban substation. Nevertheless, we demonstrate the robustness of medium voltage electric

H. Turker; A. Florescu; S. Bacha; D. Chatroux

2011-01-01

291

Time-lapse 2D electrical resistivity tomographies for investigating the Picerno landslide (Basilicata Region, southern Italy)  

NASA Astrophysics Data System (ADS)

The rainwater infiltration into the soil and the increase of pore water pressure in the vadose zone can be considered the main causes of shallow landslides triggering. The standard techniques used to measure the water content of the soil and the piezometric levels in areas of potential instability are the TDR method and the piezometric measurements, respectively. These techniques, while allowing to obtain direct information of the considered parameter, provide a punctual information about the specific hydrological characteristics of the investigated soil. Recently, the literature reports many examples of applications of indirect methods for the study and the estimate of water content in the first layers of the subsoil. In particular, the 2D electrical resistivity tomography has been applied for obtaining information about the temporal and spatial patterns of water infiltration processes. This paper reports the results obtained in the area affected by the Picerno landslide (Basilicata Region, Southern Italy), which represents one of the test sites of Morfeo project (Monitoraggio e Rischio da Frana mediante dati EO) funded by the Italian Space Agency (ASI). The studied slope has been frequently involved in reactivation phenomena the most recent of which occurred on March 2006. In the area, we have installed a prototype system for time-dependent analysis of electrical resistivity images and TDR measurements. The geophysical results are opportunely integrated with the piezometric data. The system is composed of a 48-channel cable connected to the georesistivimeter Syscal Pro Switch 48, the electrodes are placed at a distance of 1 m. Two holes used to measure the piezometric level and another four equipped with TDR probes are located along the acquisition profile. The electrical resistivity tomographies and the water content measurements are performed with time intervals selected by considering the rainfall intensity and frequency. The first preliminary result of this experiment are presented and discussed.

Luongo, Raffaele; de Bari, Claudia; Calamita, Giuseppe; Loperte, Antonio; Perrone, Angela; Satriani, Antonio; Votta, Mario; Lapenna, Vincenzo

2010-05-01

292

Effect of electric slag remelting on the corrosion-cracking resistance of steel 16GNMA  

Microsoft Academic Search

We investigated the influence of electric slag remelting and electric slag welding (ESW) on the resistance of steel 16GNMA to alkaline cracking. The experiments were done in a potential-static cycle (the comparison electrode consisted of a mercury-mercurou s oxide electrode, the potential of which compared with the normal hydrogen electrode equals 85 mV) with a single axial tension on the

I. I. Vasilenko; R. K. Melekhov; N. A. Langer; Z. V. Yushkevich

1973-01-01

293

Electrical resistivity tomography mapping of beachrocks: application to the island of Thassos (N. Greece)  

Microsoft Academic Search

Electrical resistivity tomography (ERT) technique is widely used in mapping subsurface electrical properties. In this study,\\u000a ERT was used to map a beachrock outcrop, extended both inland, under beach sediments, and seawards, on and under seafloor\\u000a sediments. Mapping of beachrock is considered important because it can help evaluate the lateral and vertical extend of the\\u000a formation. Fast and reliable mapping

Psomiadis David; Tsourlos Panagiotis; Albanakis Konstantinos

2009-01-01

294

Electrical Resistivity of Liquid Ge2Sb2Te5 in Patterned Nanostructures  

NASA Astrophysics Data System (ADS)

Phase change memory devices are based on the electrical resistivity contrast between the amorphous and the crystalline phases of chalcogenide materials [1]. Since melting is required to amorphize the material, knowledge of the liquid state properties is critical for device design. Ge2Sb2Te5 (GST) is the most studied phase change material. However, the two experimental values reported to date for electrical resistivity of liquid GST (one on a thin film [2], the other in bulk [3]) differ by an order of magnitude. We have extracted the electrical resistivity of liquid GST from single pulse measurements on a large number of encapsulated GST line structures with varying lengths, widths and thicknesses. Each structure is self-heated to melt by the microsecond voltage pulse while voltage and current are monitored using an oscilloscope. The liquid state resistivity is calculated from slopes of liquid state resistance versus 1/width, fitted as a function of length. The results we obtained for the liquid resistivity of GST in nanostructures are close to those obtained from measurements on bulk GST [3]. 1. H. Wong et al., Proc IEEE 98, 2201, 2010. 2. T. Kato and K. Tanaka, Jap. J. Appl. Phys. 44, 7340, 2005. 3. R. Endo et al., Jap. J. Appl. Phys. 49, 5802, 2010.

Cil, Kadir; Dirisaglik, Faruk; Wennberg, Maren; King, Adrienne; Akbulut, Mustafa; Zhu, Yu; Lam, Chung; Silva, Helena; Gokirmak, Ali

2012-02-01

295

Mechanical flexible and electric fatigue resistant behavior of relaxor ferroelectric terpolymer  

NASA Astrophysics Data System (ADS)

Uniaxial tension and polarization evolution under cyclic electric field are investigated for poly(vinylidene fluoride-trifluorethylene-chlorofluoroethylene) terpolymer films prepared by different annealing conditions. The stress-strain behavior of the terpolymer film exhibits that of polymeric elastomers, with its fracture strain reaching 680%. Structure analysis demonstrates that the polymer chains undergo reorientation, and conformational change from nonpolar to polar phase takes place during uniaxial tension. Under cyclic electric field, the terpolymer film exhibits a narrow polarization loop typical of a ferroelectric relaxor. Conformational change from nonpolar to polar phase also occurs upon the electric field, and it reverses to the nonpolar phase when the field is removed. As the cycle number accumulates, the terpolymer film demonstrates excellent resistance to electric fatigue. Compared to the film annealed at 115 °C, the terpolymer film annealed at 100 °C has a larger volume fraction of crystallite/amorphous interfaces and shows better mechanical flexibility as well as electric fatigue resistance. The mechanical flexible and electric fatigue resistant terpolymer films hold promises for many applications, ranging from embedded sensors and actuators to flexible memory devices.

Fang, Fei; Yang, Wei; Yang, Wen

2009-08-01

296

Stark Profiles In Plasmas Interacting With A Strong Oscillatory Quasi-Monochromatic Electric Field  

SciTech Connect

This paper presents an advanced analysis of the spectroscopic signatures of the interaction of a strong oscillating Quasi-monochromatic Electric Field (QEF), generated by a high-power short-pulse laser, with a preformed laser-produced plasma. The computation of a synthetic spectrum emitted by such plasmas requires the calculation of the Stark line shape in the presence of a QEF and the evaluation of the QEF intensity profile throughout the line of sight in the plasma. As for the Stark profiles in hot dense plasmas submitted to a strong QEF, they are calculated using the so-called Floquet-Liouville formalism. In this formalism, the Liouville space, usually used for the calculation of Stark profiles in dense plasmas, and the Floquet theory, developed to solve time-periodic problems, have been joined together to solve the time-dependent Liouville equation. A second kind of simulations involving Particle-In-Cell PIC kinetic simulations is required for the calculation of the QEF inhomogeneous intensity and the exotic features exhibited in the spectroscopic diagnostic. The global synthetic profile is obtained integrating all individual contributions for every time and location in the plasma. Finally, a spectroscopic analysis of the experimental Al He {beta} line is performed using the tools presented in this work. The spectroscopic signatures of the QEF show up as prominent satellites, non symmetrical with respect to the unperturbed line and distinguishable from the di-electronic satellites.

Sauvan, P. [Departamento de Ingenieria Energetica, ETS Ingenieros Industriales, UNED, C/Juan del Rosal 12, 28040 Madrid (Spain); Dalimier, E.; Riconda, C. [Laboratoire pour l'Utilisation des Lasers Intenses UMR 7605, CNRS-CEA-Ecole Polytechnique-Universite Paris 6, case 128, 4 Place Jussieu, 75252 Paris Cedex 05 and 91128 Palaiseau (France); Oks, E. [Physics Department, 206 Allison Laboratory, Auburn University, Auburn, AL 36849 (United States); Renner, O. [Institute of Physics, Academy of Sciences CR, Na Slovance 2, 18221 Prague (Czech Republic); Weber, S. [CELIA Universite Bordeaux-CNRS-CEA, 33405 Talence (France)

2010-10-29

297

A upper mantle electrical conductivity profile beneath the Australian continent and a comparison with a laboratory-based model  

NASA Astrophysics Data System (ADS)

To investigate the standard electrical conductivity profile beneath a continental craton, we conducted magnetotelluric observations with long dipole span near Alice Springs, central Australia. Central Australia is located in mid-geomagnetic latitudes, which makes it suitable to conduct magnetotelluric studies and its location in the center of a continent means we can expect the oceanic effect to be minimized. Moreover, seismic tomographic studies detect no lower mantle upwelling beneath Australia. We utilized geomagnetic data acquired at the Alice Springs geomagnetic observatory maintained by Geoscience Australia. The power spectrum densities of 3 components of the geomagnetic data are not distinctive at four principal tidal constituents (M2, S2, O1, and K1) frequencies except S2, which suggest the observed electromagnetic field variations are not affected by motional induction. Using the BIRRP processing code (Chave and Thomson, 2004), we estimated the MT and GDS transfer functions from 100 to 106 sec in period. The MT-compatible response functions converted from GDS response functions are resistive compared to the Canadian Shield (Chave et al., 1993) around 105 sec in period. The calculated MT responses have also resistive apparent resistivity values in overall period range. We inverted the average MT responses into a one-dimensional conductivity structure with the Occam inversion (Constable et al., 1987). We compared the resultant one-dimensional structure with the electrical conductivity profiles predicted from the compositional models of the earth's upper mantle by calculating phase diagrams in the CFMAS (CaO-FeO-MgO-Al2O3-SiO2) system. The on-craton and off-craton chemical composition models (Rudnick et al., 1998) were adopted for tectosphere. The Perple_X (e.g. Connolly, 2005) programs were utilized for obtaining mineral proportions and compositions with depth by minimizing the total Gibbs free energy. The used thermodynamic data base was SFO05 (Stixrude and Lithgow-Bertelloni, 2005; Fabrichnaya, 1998; Ono and Oganov, 2005). The adiabat, which passes through the pressure and temperature conditions constrained by both of the olivine-wadsleyite (Katsura et al., 2004) and ringwoodite-perovskite (Ito and Takahashi, 1989) phase transitions, is considered to be appropriate for the upper mantle. The appropriate adiabat itself was adopted to the thermal structure of oceanic upper mantle. On the other hand, the thermal structure of sub-continents was obtained by incorporating the effect of the mechanical boundary layer and of the crustal double heat production layers into the appropriate adiabat by means of McKenzie et al.(2005). Newly compiled laboratory data for electrical conductivity of minerals were as followings: olivine (Constable, 2006), garnet-majorite (Romano et al., 2006), wadsleyite (Yoshino et al., 2008), ringwoodite (op. cit.), and akimotoite (Katsura et al., 2007). We referred to Xu et al.(2000) for other minerals' data. The calculated conductivity profiles with on- and off-craton models still show significantly lower magnitude than the observed.

Ichiki, M.; Fujita, K.; Wang, L.; Hitchman, A. P.

2010-12-01

298

Water-Level Sensor and Temperature-Profile Detector.  

National Technical Information Service (NTIS)

A temperature profile detector is described which comprises a surrounding length of metal tubing and an interior electrical conductor both constructed of high temperature high electrical resistance materials. A plurality of gas-filled expandable bellows m...

1981-01-01

299

Heterogeneity among Virulence and Antimicrobial Resistance Gene Profiles of Extraintestinal Escherichia coli Isolates of Animal and Human Origin  

Microsoft Academic Search

Extraintestinal pathogenic Escherichia coli (ExPEC) isolates collected from different infected animals and from human patients with extraintestinal infections in 2001 were characterized for their phenotypic and genotypic antimicrobial resistance profiles, genotypes, and key virulence factors. Among the 10 antimicrobial agents tested, resistance to ampicillin, tetracycline, and sulfonamides was most frequent. Multiresistant strains were found in both the animal and the

Christine Maynard; Sadjia Bekal; Francois Sanschagrin; Roger C. Levesque; Roland Brousseau; Luke Masson; Serge Lariviere; Josee Harel; Pavillon C.-E. Marchand

2004-01-01

300

Electrical properties and fatigue resistance of polyamide 6,6 fabrics with nanocrystal silver coating.  

PubMed

Nanocrystalline silver was coated on plain woven fabrics made from continuous polyamide multifilament yarns by sputtering technique. Electrical conductivity and abrasion resistances of the coating fabric were measured. There was a minimum value of resistance when the coating thickness varies. The critical coating thickness at the minimum resistance was found to be much greater than that necessary to form a continuous layer of coating on a single fabric. X-ray diffraction (XRD) and transmission electron microscope (TEM), and field emission scanning electronic microscopy (FESEM) were employed to identify the contributing factors of dips between two adjacent parallel fibres and cross-over junction of the warp and weft yarns. PMID:19452970

Wang, R X; Tao, X M; Wang, Y; Wang, G F

2009-05-01

301

The gene expression profiles of medulloblastoma cell lines resistant to preactivated cyclophosphamide.  

PubMed

The total expression profiles of two medulloblastoma cell lines resistant to the preactivated form of cyclophosphamide (4-hydroperoxycyclophosphamide, 4-HC) were examined using the Affymetrix GeneChip U133A array. Our primary objective was to look for possible genes, other than the well-studied aldehyde dehydrogenases (ALDH) that may be involved in cyclophosphamide (CP) resistance in medulloblastomas. We present here the lists of the most highly upregulated [30 for D341 MED (4-HCR); 20 for D283 MED (4-HCR)] and downregulated [19 for D341 MED (4-HCR); 15 for D283 MED (4-HCR)] genes which may be involved in conferring CP-resistance to the two medullobalstoma cell lines. The lists of genes from the two sublines almost had no overlap, suggesting different mechanisms of CP-resistance. One of the most noteworthy upregulated gene is TAP1 [90-fold increase in D341 MED (4-HCR) relative to D341 MED]. TAP1, a protein belonging to the ABC transporter family is normally involved in major histocompatibility class I (MHC I) antigen processing. This suggests the possible role of multidrug resistance (MDR), albeit atypical (which means it does not involve the usual MDR1 and MRP glycoproteins), in medulloblastoma's CP-resistance. Apart from TAP1, a number of other genes involved in MHC1 processing were upregulated in D341 MED (4HCR). D341 MED (4-HCR) also had a 20-fold increase in the expression of the aldo-keto reductase gene, AKR1B10, which may deactivate the reactive cyclophosphamide metabolite, aldophosphamide. For D283 MED (4-HCR), the most notable increase in expression is that of ALDH1B1, a member of the aldehyde dehydrogenase (ALDH) family of proteins. PMID:18473730

Bacolod, M D; Lin, S M; Johnson, S P; Bullock, N S; Colvin, M; Bigner, D D; Friedman, H S

2008-05-01

302

The gene expression profiles of medulloblastoma cell lines resistant to preactivated cyclophosphamide  

PubMed Central

The total expression profiles of two medulloblastoma cell lines resistant to the preactivated form of cyclophosphamide (4-hydroperoxycyclophosphamide, 4-HC) were examined using the Affymetrix GeneChip U133A array. Our primary objective was to look for possible genes, other than the well-studied aldehyde dehydrogenases (ALDH) that may be involved in cyclophosphamide (CP) resistance in medulloblastomas. We present here the lists of the most highly upregulated [30 for D341 MED (4-HCR); 20 for D283 MED (4-HCR)] and downregulated [19 for D341 MED (4-HCR); 15 for D283 MED (4-HCR)] genes which may be involved in conferring CP-resistance to the two medullobalstoma cell lines. The lists of genes from the two sublines almost had no overlap, suggesting different mechanisms of CP-resistance. One of the most noteworthy upregulated gene is TAP1 [90-fold increase in D341 MED (4-HCR) relative to D341 MED]. TAP1, a protein belonging to the ABC transporter family is normally involved in major histocompatibility class I (MHC I) antigen processing. This suggests the possible role of multidrug resistance (MDR), albeit atypical (which means it does not involve the usual MDR1 and MRP glycoproteins), in medulloblastoma’s CP-resistance. Apart from TAP1, a number of other genes involved in MHC1 processing were upregulated in D341 MED (4HCR). D341 MED (4-HCR) also had a 20-fold increase in the expression of the aldo-keto reductase gene, AKR1B10, which may deactivate the reactive cyclophosphamide metabolite, aldophosphamide. For D283 MED (4-HCR), the most notable increase in expression is that of ALDH1B1, a member of the aldehyde dehydrogenase (ALDH) family of proteins.

Lin, S.M.; Johnson, S. P.; Bullock, N.S.; Colvin, M.; Bigner, D.D.; Friedman, H.S.

2013-01-01

303

Transcriptional Profiles of the Response of Methicillin-Resistant Staphylococcus aureus to Pentacyclic Triterpenoids  

PubMed Central

Staphylococcus aureus is an important human pathogen in both hospital and the community that has demonstrated resistance to all currently available antibiotics over the last two decades. Multidrug-resistant isolates of methicillin-resistant S. aureus (MRSA) exhibiting decreased susceptibilities to glycopeptides has also emerged, representing a crucial challenge for antimicrobial therapy and infection control. The availability of complete whole-genome nucleotide sequence data of various strains of S. aureus presents an opportunity to explore novel compounds and their targets to address the challenges presented by antimicrobial drug resistance in this organism. Study compounds ?-amyrin [3?-hydroxy-urs-12-en-3-ol (AM)], betulinic acid [3?-hydroxy-20(29)-lupaene-28-oic acid (BA)] and betulinaldehyde [3?-hydroxy-20(29)-lupen-28-al (BE)] belong to pentacyclic triterpenoids and were reported to exhibit antimicrobial activities against bacteria and fungi, including S. aureus. The MIC values of these compounds against a reference strain of methicillin-resistant S. aureus (MRSA) (ATCC 43300) ranged from 64 µg/ml to 512 µg/ml. However, the response mechanisms of S. aureus to these compounds are still poorly understood. The transcription profile of reference strain of MRSA treated with sub-inhibitory concentrations of the three compounds was determined using Affymetrix GeneChips. The findings showed that these compounds regulate multiple desirable targets in cell division, two-component system, ABC transporters, fatty acid biosynthesis, peptidoglycan biosynthesis, aminoacyl-tRNA synthetase, ribosome and ?-lactam resistance pathways which could be further explored in the development of therapeutic agents for the treatment of S. aureus infections.

Chung, Pooi Yin; Chung, Lip Yong; Navaratnam, Parasakthi

2013-01-01

304

Differential gene expression profile in hepatopancreas of WSSV-resistant shrimp ( Penaeus japonicus) by suppression subtractive hybridization  

Microsoft Academic Search

In order to find the immune-relevant factors responsible for the virus resistance in the WSSV-resistant shrimp, a suppression subtractive hybridization method was employed to identify differentially expressed genes and their expression profile in the hepatopancreas of the virus-resistant penaeid shrimp. Thirty five genes were identified from more than 400 clones, of which eight are found for the first time in

Deng Pan; Nanhai He; Zhiyuan Yang; Haipeng Liu; Xun Xu

2005-01-01

305

Metagenomic Profiling of Microbial Composition and Antibiotic Resistance Determinants in Puget Sound  

PubMed Central

Human-health relevant impacts on marine ecosystems are increasing on both spatial and temporal scales. Traditional indicators for environmental health monitoring and microbial risk assessment have relied primarily on single species analyses and have provided only limited spatial and temporal information. More high-throughput, broad-scale approaches to evaluate these impacts are therefore needed to provide a platform for informing public health. This study uses shotgun metagenomics to survey the taxonomic composition and antibiotic resistance determinant content of surface water bacterial communities in the Puget Sound estuary. Metagenomic DNA was collected at six sites in Puget Sound in addition to one wastewater treatment plant (WWTP) that discharges into the Sound and pyrosequenced. A total of ?550 Mbp (1.4 million reads) were obtained, 22 Mbp of which could be assembled into contigs. While the taxonomic and resistance determinant profiles across the open Sound samples were similar, unique signatures were identified when comparing these profiles across the open Sound, a nearshore marina and WWTP effluent. The open Sound was dominated by ?-Proteobacteria (in particular Rhodobacterales sp.), ?-Proteobacteria and Bacteroidetes while the marina and effluent had increased abundances of Actinobacteria, ?-Proteobacteria and Firmicutes. There was a significant increase in the antibiotic resistance gene signal from the open Sound to marina to WWTP effluent, suggestive of a potential link to human impacts. Mobile genetic elements associated with environmental and pathogenic bacteria were also differentially abundant across the samples. This study is the first comparative metagenomic survey of Puget Sound and provides baseline data for further assessments of community composition and antibiotic resistance determinants in the environment using next generation sequencing technologies. In addition, these genomic signals of potential human impact can be used to guide initial public health monitoring as well as more targeted and functionally-based investigations.

Port, Jesse A.; Wallace, James C.; Griffith, William C.; Faustman, Elaine M.

2012-01-01

306

Electrical resistance of metallic contacts on silicon and germanium during indentation  

SciTech Connect

The effects of indentation on the electrical resistance of rectifying gold-chromium contacts on silicon and germanium have been studied using nanoindentation techniques. The DC resistance of circuits consisting of positively and negatively biased contacts with silicon and germanium in the intervening gap was measured while indenting either directly in the gap or on the contacts. Previous experiments showed that a large decrease in resistance occurs when an indentation bridges a gap, which was used to support the notion that a transformation from the semiconducting to the metallic state occurs beneath the indenter. The experimental results reported here, however, show that a large portion of the resistance drop is due to decreases in the resistance of the metal-to-semiconductor interface rather than the bulk semiconductor. Experimental evidence supporting this is presented, and a simple explanation for the physical processes involved is developed which still relies on the concept of an indentation-induced, semiconducting-to-metallic phase transformation.

Pharr, G.M. (Department of Materials Science, Rice University, P. O. Box 1892, Houston, Texas 77251 (United States)); Oliver, W.C. (Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)); Cook, R.F.; Kirchner, P.D.; Kroll, M.C.; Dinger, T.R. (IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States)); Clarke, D.R. (Materials Department, University of California at Santa Barbara, Santa Barbara, California 93106 (United States))

1992-04-01

307

Electrical resistance and tritiated water permeability as indicators of barrier integrity of in vitro human skin  

Microsoft Academic Search

The use of human skin for percutaneous penetration studies invariably involves storage of tissue prior to use, and assessment of barrier integrity is important as damage to the skin may occur during surgical removal, storage, or technical preparation. This assessment is frequently performed by measurement of skin permeability to marker chemicals, but measurement of electrical resistance is a recently proposed

J. N. Lawrence

1997-01-01

308

Thermal fluctuations near a phase transition probed through the electrical resistivity of high-temperature superconductors  

Microsoft Academic Search

We present a simple and inexpensive experimental setup that can determine the thermal fluctuations near a superconducting transition. By using equipment common in undergraduate laboratories, the in-plane dc electrical resistivity of a cuprate superconductor as a function of temperature is measured with resolution sufficient to analyze the fluctuation conductivity above the superconducting critical temperature, including the values of the critical

Noelia Cotón; Francisco J. Guzmán; Manuel V. Ramallo; Alexandre Ríos; Carolina Torrón; Félix Vidal

2010-01-01

309

Municipal solid waste in situ moisture content measurement using an electrical resistance sensor  

Microsoft Academic Search

Moisture content (MC) is a crucial parameter for degradation of solid waste in landfills. Present MC measurement techniques suffer from several drawbacks. A moisture sensor for measurement of in situ moisture content of solid waste in landfills was developed. The sensor measures the electrical resistance across the granular matrix of the sensor, which in turn can be correlated to moisture

Nitin A. Gawande; Debra R. Reinhart; Philip A. Thomas; Philip T. McCreanor; Timothy G. Townsend

2003-01-01

310

Combined Macroscopic Invasion Percolation and Continuum Modeling of Electrical Resistivity Measurements in Unsaturated Media  

Microsoft Academic Search

When coupled with unsaturated flow models, electrical resistivity techniques (including tomography) offer the promise of non-intrusive characterization of moisture within the unsaturated zone. Most unsaturated flow models (e.g., Richards' equation) are continuum models that are incapable of reproducing the complicated aqueous- phase structure observed in many field and laboratory experiments. This heterogeneous distribution of moisture contributes to highly heterogeneous distributions

R. M. Holt

2007-01-01

311

Electrical contact resistance as a diagnostic tool for MEMS contact interfaces  

Microsoft Academic Search

The electrical contact resistance (ECR) was evaluated as an in situ diagnostic tool for the contact interface behavior of microelectromechanical systems (MEMS). Special polycrystalline silicon (polysilicon) MEMS devices fabricated by surface micromachining were used to study polysilicon\\/native oxide\\/polysilicon contact interfaces. ECR measurements obtained during monotonic contact loading and unloading and cyclic contact loading are interpreted in the context of a

Ari Lumbantobing; Lior Kogut; Kyriakos Komvopoulos

2004-01-01

312

Electrical Resistivity Modeling of a Permeable Reactive Barrier for Vista Engineering Technologies: Summary  

Microsoft Academic Search

We have performed a numerical modeling study that evaluated the capacity of electrical resistance tomography (ERT) to detect flaws in a passive reactive barrier (PRB). The model barrier is based on a real barrier described in the literature Slater and Binley (2003). It consists of highly conducting, granular iron emplaced within a trench. We assumed that the barrier was filled

A L Ramirez; W D Daily

2003-01-01

313

The effect of alloy contents on electrical resistance accumulation of polycrystalline constantan under cycle loading  

Microsoft Academic Search

To get a good electrical resistance accumulation behavior under cycle loading, the alloy content in the polycrystalline constantan is one of the key issues. Based on the principle of the orthogonal experiment design, in the paper, 8 kinds of polycrystalline constantan foils containing different levels of alloy components were prepared using the same technology. Through a series of fatigue experiments

Wei-Xin Ren; Dan Xiao; Ge-Wei Chen

2011-01-01

314

Four-terminal measurement of the distribution of electrical resistance across stress corrosion cracking  

Microsoft Academic Search

This study measures electrical resistance of a stress corrosion crack directly by the four-terminal method to discuss appropriate modeling from the viewpoint of electromagnetic nondestructive evaluation. Two type-316 stainless steel plate specimens containing artificial stress corrosion cracks were prepared, and columnar samples containing penetrating cracks were cut from the plates for the measurements. The results obtained agree with recent reports

Noritaka Yusa; Hidetoshi Hashizume

2011-01-01

315

Electrical Contact Resistance Theory for Anisotropic Conductive Films Considering Electron Tunneling and Particle Flattening  

Microsoft Academic Search

This study models the electrical contact resistance (ECR) between two surfaces separated by an anisotropic conductive film. The film is made up of an epoxy with conductive spherical particles(metallic) dispersed within. In practical situations the particles are often heavily loaded and will undergo severe plastic deformation and may essentially be flattened out. In between the particles and the surfaces there

Robert L. Jackson; Lior Kogut

2007-01-01

316

Effects of Entrapped Bubble Formation on Flow Through Porous Media During Electrical Resistance Heating  

Microsoft Academic Search

In-situ thermal remediation technologies such as electrical resistance heating (ERH) have been used effectively to treat volatile organic compounds (VOCs) in a variety of subsurface conditions. Field applications have shown significant reductions in total contaminant mass over relatively short time periods. The mechanism of these technologies is well understood; the subsurface temperature is increased to boil the groundwater and the

R. B. Thoms; R. L. Johnson

2006-01-01

317

Electrical resistance tomography for monitoring the infiltration of water into a pavement section  

Microsoft Academic Search

Electrical resistance tomography (ERT) was used to follow the infiltration of water into pavement section at the UC Berkeley Richmond Field Station. A volume of pavement 1m square and 1.29 m deep was sampled by an ERT array consisting of electrodes in 9 drilled holes plus 8 surface electrodes. The data were collected using a computer controlled data acquisition system

M. Buettner; B. Daily; A. Ramirez

1997-01-01

318

Improved estimation of the resistivity of pure copper and electrical determination of thin copper film dimensions  

Microsoft Academic Search

Improved values for the resistivity, ?, of pure, bulk copper from 50 to 1200 K, and their confidence intervals, are developed by extending the analysis of Matula. A recommended value for d?\\/dT and its confidence interval in the temperature range of 290–425 K is developed for use with Matthiessen's rule to calculate the electrical thickness of thin copper films and

Constance E. Schuster; Mark G. Vangel; Harry A. Schafft

2001-01-01

319

Preliminary Investigation of Al-Jahra Waste Disposal Site Using Electrical Resistivity (ER) Surveys  

Microsoft Academic Search

In this preliminary study, a surface geophysical investigation consisting of electrical resistivity (ER) survey techniques, one of the most promising techniques was carried out on a pilot area at Al-Jahra waste dumpsite. This dumpsite, which is situated very close to a highly populated city, was decommissioned early 2007 after twenty years of service. The dumpsite was reactivated in August of

Rana A. Al-Fares; Rawa S. Al-Jarallah; Ziad Abdulsalam

320

Electrical Resistivity Imaging of Subterranean Void Space for Assessment of Endangered Species Habitat  

Microsoft Academic Search

The challenge of identifying and delineating subterranean habitat for endangered species in karst environments has been addressed through the application of near-surface geophysical techniques. Electrical resistivity imaging (ERI) in both galvanic DC and capacitance-coupled modes has been applied to the problem of imaging subsurface voids, potentially conducive to karst invertebrate habitat, in two distinctly different geologic, geophysical, and environmental settings.

B. P. Weissling; K. White

2007-01-01

321

Calculation of electrical resistivity produced by dislocations and grain boundaries in metals  

Microsoft Academic Search

The partial-wave method is used for the calculation of the residual electrical resistivity caused by dislocations and grain boundaries in various metals. The dislocation core is regarded as a resonance scattering line defect containing surplus free volume. Scattering by elastic distortions of the lattice is neglected. An estimation of the effective carrier concentration in transition metals is performed on the

A. S. Karolik; A. A. Luhvich

1994-01-01

322

Characterization and monitoring of subsurface processes using parallel computing and electrical resistivity imaging  

SciTech Connect

This newsletter discusses recent advancement in subsurface resistivity characterization and monitoring capabilities. The BC Cribs field desiccation treatability test resistivity monitoring data is use an example to demonstrate near-real time 3D subsurface imaging capabilities. Electrical resistivity tomography (ERT) is a method of imaging the electrical resistivity distribution of the subsurface. An ERT data collection system consists of an array of electrodes, deployed on the ground surface or within boreholes, that are connected to a control unit which can access each electrode independently (Figure 1). A single measurement is collected by injecting current across a pair of current injection electrodes (source and sink), and measuring the resulting potential generated across a pair of potential measurement electrodes (positive and negative). An ERT data set is generated by collecting many such measurements using strategically selected current and potential electrode pairs. This data set is then processed using an inversion algorithm, which reconstructs an estimate (or image) of the electrical conductivity (i.e. the inverse of resistivity) distribution that gave rise to the measured data.

Johnson, Timothy C.; Truex, Michael J.; Wellman, Dawn M.; Marble, Justin

2011-12-01

323

Application of 4D resistivity image profiling to detect DNAPLs plume.  

NASA Astrophysics Data System (ADS)

In July 1993, the soil and groundwater of the factory of Taiwan , Miaoli was found to be contaminated by dichloroethane, chlorobenzene and other hazardous solvents. The contaminants were termed to be dense non-aqueous phase liquids (DNAPLs). The contaminated site was neglected for the following years until May 1998, the Environment Protection Agency of Miaoli ordered the company immediately take an action for treatment of the contaminated site. Excavating and exposing the contaminated soil was done at the previous waste DNAPL dumped area. In addition, more than 53 wells were drilled around the pool with a maximum depth of 12 m where a clayey layer was found. Continuous pumping the groundwater and monitoring the concentration of residual DNAPL contained in the well water samples have done in different stages of remediation. However, it is suspected that the DNAPL has existed for a long time, therefore the contaminants might dilute but remnants of a DNAPL plume that are toxic to humans still remain in the soil and migrate to deeper aquifers. A former contaminated site was investigated using the 2D, 3D and 4D resisitivity image technique, with aims of determining buried contaminant geometry. This paper emphasizes the use of resistivity image profiling (RIP) method to map the limit of this DNAPL waste disposal site where the records of operations are not variations. A significant change in resistivity values was detected between known polluted and non-polluted subsurface; a high resistivity value implies that the subsurface was contaminated by DNAPL plume. The results of the survey serve to provide insight into the sensitivity of RIP method for detecting DNAPL plumes within the shallow subsurface, and help to provide valuable information related to monitoring the possible migration path of DNAPL plume in the past. According to the formerly studies in this site, affiliation by excavates with pumps water remediation had very long time, Therefore this research was used iron nanoparticles with pumps water remediation ways. The survey lines use the same length and the same position of the different time observation. The survey lines monitors the iron nanoparticles and pollution flow direction with remediation effect. By used the iron nanoparticles and pumping water remediation ways, the DNAPL plumes had eminent changed. Iron nanoparticles granule is smaller than the micron iron, Therefore the reaction rate was quite quick at the iron nanoparticles and pumps, but the ferric oxide can cause the electronic resistivity to elevate produces after the response. Pumps water rectifies may remove the ferric oxide to cause the electronic resistivity to reduce. The iron nanoparticles and pollution response is extremely obviously of the Resistivity Image Profile.

Liu, H.; Yang, C.; Tsai, Y.

2008-12-01

324

Electrical resistivity investigations for guiding and controlling fresh water well drilling in semi-arid region in Khanasser Valley, Northern Syria  

NASA Astrophysics Data System (ADS)

Electrical resistivity survey is conducted in the Khanasser Valley, considered as a semi-arid region in Northern Syria, to guide and control fresh water well drilling. Vertical Electrical Soundings (VES) are carried out near the existing wells, which were also used to measure salinity and conductivity of water samplings. Resistivity and hydrogeological data combination made it possible to establish empirical relationships between earth resistivity, water resistivity, and the amount of total dissolved solids (TDS). These relationships are used in the present research in order to follow the TDS salinity variations, both in lateral and depth directions, along the longitudinal profile LP3, located in Khanasser Valley. Apparent salinity map under this profile is established for Quaternary and Paleogene deposits, and boundaries of suitable areas for fresh water well drilling in the totality of the Khanasser Valley are drawn. It was shown that excessive fresh-water depletion may affect the groundwater quality by upward seepage of saline water. Therefore, it is important to keep the fresh-salt water interface in a stationary situation. The geoelectrical methods widely contribute in determining the position of such interface, and can be easily applied in similar arid areas.

Asfahani, Jamal

2011-02-01

325

Electrical resistance of island-containing thin metal interconnects on polymer substrates under high strain  

SciTech Connect

We have deposited thin metal films that include a granular indium layer on polymer substrates and observed the resistance of the film changed by a factor of less than 2, even as the sample is uniaxially stretched to the point of rupture ({approx}38% strain). The presence of a discontinuous layer of indium islands in these films maintains the electrical conductivity by providing a bridging mechanism across the cracks formed in the underlying continuous film layers. A simple model is used to relate the applied strain to the electrical resistance of the metal films. Furthermore, we present the data for these films under cyclic loading around a cylindrical mandrel which show that there is no change in resistance under these fatigue testing conditions for 10 000 loading cycles.

Wang, D.P.; Biga, Frederick Y.; Zaslavsky, A.; Crawford, Gregory P. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Division of Engineering, Brown University, Providence, Rhode Island 02912 (United States); Division of Engineering and Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)

2005-10-15

326

Electrical resistivity and thermopower of ErCo3 under hydrostatic pressure  

NASA Astrophysics Data System (ADS)

The magnetic state of the Co 3d-electron subsystem of RCo3 compounds (R=rare-earth elements) with the rhombohedral PuNi3-type structure strongly depends on external parameters. In order to clarify the effect of pressure on the magnetic state of the itinerant Co 3d-electrons, we have measured the electrical resistivity and thermopower at temperatures from 2 K to 300 K under hydrostatic pressures up to 2 GPa. Both, ? and S show anomalies at critical temperature of metamagnetic transition Tm. With increasing pressure Tm, determined from the temperature-dependent resistivity and thermopower, decreases and apparently vanishes at P approx 0.7 GPa. The electrical resistivity and thermopower at low temperatures show abrupt changes at P approx 0.7 GPa, indicating a pressure-induced phase transition.

Nakama, T.; Niki, H.; Nakamura, D.; Takaesu, Y.; Hedo, M.; Yagasaki, K.; Uchima, K.; Gratz, E.; Burkov, A. T.

2009-03-01

327

High Pressure Electrical Resistivity Study of Sm0.85Nd0.15Se  

NASA Astrophysics Data System (ADS)

The study of rare-earth monochalcogenides have received much attention because of their interesting electrical properties. They crystallize in the NaCl type structure and are semiconducting if the rare earth ion is in the divalent state and metalic if trivalent state. The effect of substitution of trivalent rare earth ion in divalent rare earth has been studied. We present the results of electrical resistivity measurements and lattice parameter study on Sm0.85Nd0.15Se. The structure of the sample is confirmed by the theoretical calculation of X-ray intensities using Lazy-Pulverix programme. The electrical resistivity is found to be decreasing with the increase of pressure.

Ariponnammal, S.; Natarajan, S.

328

Assessment of Continuous Resistivity Profiling for the Characterization of Paved Roads  

NASA Astrophysics Data System (ADS)

We have assessed the continuous resistivity profiling method using towed arrays as a diagnostic NDT method for the evaluation of pavements. Whether the pavement consists of a sequence of asphalt, concrete slab and subgrade layer (rigid pavement) or a layer of asphalt overlying a subgrade and grade base layers (flexible pavement) defects within those different layers can cause pavement deterioration that must be identified. We first examine the response of the method to the various problems using numerical modeling. It is shown that with an optimally designed system the method allows the determination of the thickness and the location of cracks in the asphalt cover. It is also sensitive to the presence of cracks, internal defects and chloride ions (de-icing salt) within the concrete slab below. For reinforced concrete it is possible to estimate the concrete resistivity related directly to its composition (quality) and the thickness of the top coating over the level of rebars. A low resistivity of concrete will usually be diagnostic of advanced stage of rebar corrosion and delamination could occur. However it is shown that the rebars cause current channeling and the depth of investigation is limited then to the depth of the first row of rebars. Finally heterogeneities within the foundation reflecting subsidence, bad drainage, frost-defrost cycles or cavities can be mapped. The optimal design is based on a system with 10 to 20 receiver dipoles and one transmitter dipole (first or last of the array) with a dipole length typically of 10 cm that can be used in equatorial or in-line mode. Static resistivity measurements have been carried out at the laboratory scale over concrete slabs built to verify results obtained from the numerical modeling. Observed data fit very well the modeled data and validate the overall conclusions. Tests have been performed in December 2003 in some selected streets (6 visited, 3 re-visited) of Montreal using a CORIM system (Iris Instruments, France), a capacitively-coupled resistivity towed equatorial array that continuously record data collected with six receiver dipoles and one transmitter dipole. Typical acquisition sampling and velocity were 0,20-0,50 m and 1 to 2 km/h respectively. Although the system is not optimally designed for the applications described above it provides useful diagnostic information about the state of deterioration of pavement. Data have been imaged using 2D resistivity inversion. In general it shows a high resistivity for the shallow depth related to the asphalt layer and a decreasing resistivity with depth related to the concrete slab first and the granular foundation below. Lateral variations appear to be correlated with degradation of the concrete slab.

Chouteau, M.; Vallieres, S.; Miralles, M.

2004-05-01

329

Electrical Insulating and Heat-Resistive Properties of PDMS-TEOS Hybrid with Different Molar Ratio of TEOS to PDMS  

Microsoft Academic Search

The hybrids prepared from polydimethylsiloxane (PDMS) and tetraethoxysilane (TEOS) have been well known to be rubbery hybrid materials. In this report, the authors have investigated the electrical insulating and heat resistive properties of the hybrids by changing the molar ratio of TEOS to PDMS. The electrical insulating properties are evaluated by volume resistivity and AC breakdown strength at room temperature.

Makoto Sugiura; Fumitoshi Imasato; Atsushi Ohno; Yusuke Aoki; Shuhei Nakamura; Tetsushi Okamoto; Takuya Shindou

2007-01-01

330

A Serum Protein Profile Predictive of the Resistance to Neoadjuvant Chemotherapy in Advanced Breast Cancers*  

PubMed Central

Prediction of the responses to neoadjuvant chemotherapy (NACT) can improve the treatment of patients with advanced breast cancer. Genes and proteins predictive of chemoresistance have been extensively studied in breast cancer tissues. However, noninvasive serum biomarkers capable of such prediction have been rarely exploited. Here, we performed profiling of N-glycosylated proteins in serum from fifteen advanced breast cancer patients (ten patients sensitive to and five patients resistant to NACT) to discover serum biomarkers of chemoresistance using a label-free liquid chromatography-tandem MS method. By performing a series of statistical analyses of the proteomic data, we selected thirteen biomarker candidates and tested their differential serum levels by Western blotting in 13 independent samples (eight patients sensitive to and five patients resistant to NACT). Among the candidates, we then selected the final set of six potential serum biomarkers (AHSG, APOB, C3, C9, CP, and ORM1) whose differential expression was confirmed in the independent samples. Finally, we demonstrated that a multivariate classification model using the six proteins could predict responses to NACT and further predict relapse-free survival of patients. In summary, global N-glycoproteome profile in serum revealed a protein pattern predictive of the responses to NACT, which can be further validated in large clinical studies.

Hyung, Seok-Won; Lee, Min Young; Yu, Jong-Han; Shin, Byunghee; Jung, Hee-Jung; Park, Jong-Moon; Han, Wonshik; Lee, Kyung-Min; Moon, Hyeong-Gon; Zhang, Hui; Aebersold, Ruedi; Hwang, Daehee; Lee, Sang-Won; Yu, Myeong-Hee; Noh, Dong-Young

2011-01-01

331

Nearly Constant Electrical Resistance over Large Temperature Range in Cu3NMx (M = Cu, Ag, Au) Compounds  

PubMed Central

Electrical resistance is a material property that usually varies enormously with temperature. Constant electrical resistivity over large temperature range has been rarely measured in a single solid. Here we report the growth of Cu3NMx (M = Cu, Ag, Au) compound films by magnetron sputtering, aiming at obtaining single solids of nearly constant electrical resistance in some temperature ranges. The increasing interstitial doping of cubic Cu3N lattice by extra metal atoms induces the semiconductor-to-metal transition in all the three systems. Nearly constant electrical resistance over 200?K, from room temperature downward, was measured in some semimetallic Cu3NMx samples, resulting from opposite temperature dependence of carrier density and carrier mobility, as revealed by Hall measurement. Cu3NAgx samples have the best performance with regard to the range of both temperature and doping level wherein a nearly constant electrical resistance can be realized. This work can inspire the search of other materials of such a quality.

Lu, Nianpeng; Ji, Ailing; Cao, Zexian

2013-01-01

332

Genetic diversity, antimicrobial resistance, and toxigenic profiles of Bacillus cereus strains isolated from Sunsik.  

PubMed

Bacillus cereus can cause emetic and diarrheal types of food poisoning, but little study has been done on the toxins and toxin-encoding genes of B. cereus strains isolated from Sunsik, a Korean ready-to-eat food prepared from grains, fruits, and vegetables. In this study, 39 unique B. cereus strains were isolated and identified from Sunsik samples, with an average contamination level of 10 to 200 CFU/g. The detection rates of the hblACD, cytK, and bceT genes among all the strains were 48.7, 66.7, and 87.1%, respectively. All 39 B. cereus strains carried nheABC and entFM genes, and 36 strains also had the ces gene, which encodes an emetic toxin. Nonhemolytic enterotoxin and hemolysin BL enterotoxin were produced by 39 and 26 strains, respectively. The strains were separated into 13 profiles based on the presence or absence of toxins and their genes, as determined by antibody tests and PCR analysis. Profile 1 was the largest group, comprising 30.7% (12 of 39) of the B. cereus strains tested; these strains harbored all toxins and their genes. The B. cereus strains were susceptible to most of the antibiotics tested but were highly resistant to b -lactam antibiotics. The repetitive element sequence polymorphism PCR fingerprints of the B. cereus strains were not influenced by the presence of toxin genes or antibiotic resistance profiles. Our results suggest that B. cereus strains from Sunsik could cause either the diarrheal or emetic types of food poisoning because all strains isolated contained at least one toxin and its gene, although the level of B. cereus contamination in Sunsik was low. PMID:22289581

Lee, Nari; Sun, Je Min; Kwon, Kyung Yoon; Kim, Hyun Jung; Koo, Minseon; Chun, Hyang Sook

2012-02-01

333

Monitoring six-phase ohmic heating of contaminated soils using electrical resistance tomography  

SciTech Connect

Electrical resistance tomography (ERT) was used to monitor six-phase ohmic heating used for the insitu remediation of volatile organic compounds from subsurface water and soil at the Savannah River Site, near Aiken, South Carolina. The changes in electrical conductivity caused by six-phase ohmic-heating in a clay layer located in the vadose zone were monitored during a period of approximately 2 months, before, during and after heating. From an array of electrodes located in 4 boreholes, we collected electrical resistivity data between five pairs of adjacent holes pairs. This data was used to calculate tomographs which showed the electrical conductivity changes along five vertical planes. The difference tomographs show the combined effects of moisture redistribution and heating caused by six-phase heating and vapor extraction. The tomographs show that most of the clay layer increased in electrical conductivity during the first 3 weeks of the 4 week long heating phase. At this time, the electrical conductivities near the center of the heating array were twice as large as the pre-heat conductivities. Then the electrical conductivity started to decrease for portions of the clay layer closest to the vapor extraction well. We propose that the conductivity decreases are due to the removal of moisture by the heating and vacuum extraction. Parts of the clay layer near the extraction well reached electrical conductivities as low as 40% of the pre-heating values. We propose that these regions of lower than ambient electrical conductivities are indicators of regions where the vapor removal by vacuum extraction was most effective. At the end of the heating phase, our estimates suggest that the clay saturation may have dropped to as low as 10% based on the observed conductivity changes.

Ramirez, A.L.; Daily, W.D.

1994-09-01

334

Neurocognitive profiles in treatment-resistant bipolar I and bipolar II disorder depression  

PubMed Central

Background The literature on the neuropsychological profiles in Bipolar disorder (BD) depression is sparse. The aims of the study were to assess the neurocognitive profiles in treatment-resistant, acutely admitted BD depression inpatients, to compare the neurocognitive functioning in patients with BD I and II, and to identify the demographic and clinical illness characteristics associated with cognitive functioning. Methods Acutely admitted BD I (n?=?19) and BD II (n?=?32) inpatients who fulfilled the DSM-IV-TR criteria for a major depressive episode were tested with the MATRICS Consensus Cognitive Battery (MCCB), the Wechsler Abbreviated Scale of Intelligence, the National Adult Reading Test, and a battery of clinical measures. Results Neurocognitive impairments were evident in the BD I and BD II depression inpatients within all MCCB domains. The numerical scores on all MCCB-measures were lower in the BD I group than in the BD II group, with a significant difference on one of the measures, category fluency. 68.4% of the BD I patients had clinically significant impairment (>1.5 SD below normal mean) in two or more domains compared to 37.5% of the BD II patients (p?=?0.045). A significant reduction in IQ from the premorbid to the current level was seen in BD I but not BD II patients. Higher age was associated with greater neurocognitive deficits compared to age-adjusted published norms. Conclusions A high proportion of patients with therapy-resistant BD I or II depression exhibited global neurocognitive impairments with clinically significant severity. The cognitive impairments were more common in BD I compared to BD II patients, particularly processing speed. These findings suggest that clinicians should be aware of the severe neurocognitive dysfunction in treatment-resistant bipolar depression, particularly in BD I. Trial registration Trial registration number: NCT00664976

2013-01-01

335

A longitudinal, integrated, clinical, histological and mRNA profiling study of resistance exercise in myositis.  

PubMed

Polymyositis and dermatomyositis are orphan, chronic skeletal muscle disorders characterized by weakness, infiltrations by mononuclear inflammatory cells, and fibrosis. Until recently, patients were advised to refrain from physical activity because of fears of exacerbation of muscle inflammation. However, recent studies have shown that moderate exercise training in combination with immunosuppressive drugs can improve muscle performance. Despite the positive effects of exercise training, the molecular mechanisms underlying the exercise-associated clinical improvements remain poorly understood. The present study was designed to define, at the molecular level, the effects of resistance exercise training on muscle performance and disease progression in myositis patients. We evaluated changes in muscle strength, histology and genome-wide mRNA profiles to determine the beneficial effects of exercise and determine the possible molecular changes associated with improved muscle performance. A total of 8 myositis patients underwent a 7-wk resistance exercise training program that resulted in improved muscle strength and increased maximal oxygen uptake (VO(2max)). Training also resulted in marked reductions in gene expression, reflecting reductions in proinflammatory and profibrotic gene networks, changes that were also accompanied by a reduction in tissue fibrosis. Consistent with the exercise-associated increase in VO(2max), a subset of transcripts was associated with a shift toward oxidative metabolism. The changes in gene expression reported in the present study are in agreement with the performance improvements induced by exercise and suggest that resistance exercise training can induce a reduction in inflammation and fibrosis in skeletal muscle. PMID:20809047

Nader, Gustavo A; Dastmalchi, Maryam; Alexanderson, Helene; Grundtman, Cecilia; Gernapudi, Ramkishore; Esbjörnsson, Mona; Wang, Zuyi; Rönnelid, Johan; Hoffman, Eric P; Nagaraju, Kanneboyina; Lundberg, Ingrid E

2010-08-16

336

Electrical and thermal properties of electrically conductive adhesives using a heat-resistant epoxy binder  

Microsoft Academic Search

Heat resistant conductive adhesives composed of a multi-functional epoxy matrix containing Ag flakes were developed in this work. The adhesives are potentially stable up to 200-250degC because the primary relaxation mechanism of the matrix resin occurs at ~250degC. However, the adhesives appeared to exhibit another relaxation mechanism at an intermediate temperature range (100-180degC) when a mono-epoxide was added to the

Masahiro Inoue; Johan Liu

2008-01-01

337

Local tests of parallel electrical resistivity in the Tokamak Fusion Test Reactor  

SciTech Connect

The motional Stark effect (MSE) polarimeter measures the local magnetic field pitch angle, proportional to the ratio of the poloidal to toroidal magnetic fields, in the Tokamak Fusion Test Reactor (TFTR). The authors have used the polarimeter to measure the temporal evolution of the local value of the magnetic field pitch angle during large changes in the current profile such as during a current ramp or discharge initiation. The measured evolution is compared to the evolution predicted by classical and neoclassical resistivity models. The neoclassical resistivity model is a better predictor of the local pitch angle temporal evolution than the classical model.

Batha, S.H.; Levinton, F.M. [Fusion Physics and Technology, Inc., Torrance, CA (United States); Ramsey, A.T.; Schmidt, G.L.; Zarnstorff, M.C. [Princeton Univ., NJ (United States). Princeton Plasma Physics Lab.

1997-01-01

338

The effect of surface roughness, oxide film thickness and interfacial sliding on the electrical contact resistance of aluminium  

Microsoft Academic Search

Contact resistance measurements were made on aluminium alloy sheet with a configuration relevant to electrical resistance spot welding. Previous work has shown that a small amount of sliding is required at the interface to break down contact resistance when the material has a thin, insulating coating. Sliding on a macroscopic scale occurs at the electrode-sheet interface but not at the

E Crinon; J. T Evans

1998-01-01

339

Long-term electrical resistivity monitoring of recharge-induced contaminant plume behavior.  

PubMed

Geophysical measurements, and electrical resistivity tomography (ERT) data in particular, are sensitive to properties that are related (directly or indirectly) to hydrological processes. The challenge is in extracting information from geophysical data at a relevant scale that can be used to gain insight about subsurface behavior and to parameterize or validate flow and transport models. Here, we consider the use of ERT data for examining the impact of recharge on subsurface contamination at the S-3 ponds of the Oak Ridge Integrated Field Research Challenge (IFRC) site in Tennessee. A large dataset of time-lapse cross-well and surface ERT data, collected at the site over a period of 12 months, is used to study time variations in resistivity due to changes in total dissolved solids (primarily nitrate). The electrical resistivity distributions recovered from cross-well and surface ERT data agrees well, and both of these datasets can be used to interpret spatiotemporal variations in subsurface nitrate concentrations due to rainfall, although the sensitivity of the electrical resistivity response to dilution varies with nitrate concentration. Using the time-lapse surface ERT data interpreted in terms of nitrate concentrations, we find that the subsurface nitrate concentration at this site varies as a function of spatial position, episodic heavy rainstorms (versus seasonal and annual fluctuations), and antecedent rainfall history. These results suggest that the surface ERT monitoring approach is potentially useful for examining subsurface plume responses to recharge over field-relevant scales. PMID:23103519

Gasperikova, Erika; Hubbard, Susan S; Watson, David B; Baker, Gregory S; Peterson, John E; Kowalsky, Michael B; Smith, Meagan; Brooks, Scott

2012-10-04

340

Inspection of earthen embankment dams using time lapse electrical resistivity tomography  

NASA Astrophysics Data System (ADS)

According to the National Inventory of Dams (NID), the number of dams across the United States is approximately 85,000. Many of these dams are more than 50 years old and need vast attention to ensure their safety. It is difficult to obtain a full assessment of the dam just by visual inspections alone. This is because many problems associated with dam failure occur internally, which makes it difficult to be observed by the dam inspectors. Examples of these flaws are piping and seepage (flow of water through or around dam walls). It is in this area where geophysical methods can aid in obtaining a more confident evaluation of a dam's integrity. Electrical resistivity is one geophysical technique that would be useful in detecting internal flaws associated with seepage and piping because it is sensitive to moisture changes. A study is being conducted to examine the feasibility of electrical resistivity tomography (ERT) to map and monitor internal compromised zones within earthen embankment dams. Two quarter-scaled earthen embankment dams were built at the United States Department of Agriculture (USDA) Agriculture Research Service (ARS) Hydraulics and Engineering Research Unit (HERU) in Stillwater, Oklahoma. These two dams were constructed with known internal compromised zones that are susceptible to seepage and piping. Electrical resistivity surveys were conducted on the completed dams using a 56 electrode dipole-dipole array. The collected data was then processed using electrical resistivity tomography (ERT) imaging software and evidence of these two compromised zones was easily visible. Also, additional surveys were conducted in order to monitor the changes in electrical signatures associated with changes in these zones due to filling of the reservoir and environmental/climate changes.

Case, Jared S.

341

Global Transcriptional Profiling of Longitudinal Clinical Isolates of Mycobacterium tuberculosis Exhibiting Rapid Accumulation of Drug Resistance  

PubMed Central

The identification of multidrug resistant (MDR), extensively and totally drug resistant Mycobacterium tuberculosis (Mtb), in vulnerable sites such as Mumbai, is a grave threat to the control of tuberculosis. The current study aimed at explaining the rapid expression of MDR in Directly Observed Treatment Short Course (DOTS) compliant patients, represents the first study comparing global transcriptional profiles of 3 pairs of clinical Mtb isolates, collected longitudinally at initiation and completion of DOTS. While the isolates were drug susceptible (DS) at onset and MDR at completion of DOTS, they exhibited identical DNA fingerprints at both points of collection. The whole genome transcriptional analysis was performed using total RNA from H37Rv and 3 locally predominant spoligotypes viz. MANU1, CAS and Beijing, hybridized on MTBv3 (BuG@S) microarray, and yielded 36, 98 and 45 differentially expressed genes respectively. Genes encoding transcription factors (sig, rpoB), cell wall biosynthesis (emb genes), protein synthesis (rpl) and additional central metabolic pathways (ppdK, pknH, pfkB) were found to be down regulated in the MDR isolates as compared to the DS isolate of the same genotype. Up regulation of drug efflux pumps, ABC transporters, trans-membrane proteins and stress response transcriptional factors (whiB) in the MDR isolates was observed. The data indicated that Mtb, without specific mutations in drug target genes may persist in the host due to additional mechanisms like drug efflux pumps and lowered rate of metabolism. Furthermore this population of Mtb, which also showed reduced DNA repair activity, would result in selection and stabilization of spontaneous mutations in drug target genes, causing selection of a MDR strain in the presence of drug pressures. Efflux pump such as drrA may play a significant role in increasing fitness of low level drug resistant cells and assist in survival of Mtb till acquisition of drug resistant mutations with least fitness cost.

Chatterjee, Anirvan; Saranath, Dhananjaya; Bhatter, Purva; Mistry, Nerges

2013-01-01

342

Global transcriptional profiling of longitudinal clinical isolates of Mycobacterium tuberculosis exhibiting rapid accumulation of drug resistance.  

PubMed

The identification of multidrug resistant (MDR), extensively and totally drug resistant Mycobacterium tuberculosis (Mtb), in vulnerable sites such as Mumbai, is a grave threat to the control of tuberculosis. The current study aimed at explaining the rapid expression of MDR in Directly Observed Treatment Short Course (DOTS) compliant patients, represents the first study comparing global transcriptional profiles of 3 pairs of clinical Mtb isolates, collected longitudinally at initiation and completion of DOTS. While the isolates were drug susceptible (DS) at onset and MDR at completion of DOTS, they exhibited identical DNA fingerprints at both points of collection. The whole genome transcriptional analysis was performed using total RNA from H37Rv and 3 locally predominant spoligotypes viz. MANU1, CAS and Beijing, hybridized on MTBv3 (BuG@S) microarray, and yielded 36, 98 and 45 differentially expressed genes respectively. Genes encoding transcription factors (sig, rpoB), cell wall biosynthesis (emb genes), protein synthesis (rpl) and additional central metabolic pathways (ppdK, pknH, pfkB) were found to be down regulated in the MDR isolates as compared to the DS isolate of the same genotype. Up regulation of drug efflux pumps, ABC transporters, trans-membrane proteins and stress response transcriptional factors (whiB) in the MDR isolates was observed. The data indicated that Mtb, without specific mutations in drug target genes may persist in the host due to additional mechanisms like drug efflux pumps and lowered rate of metabolism. Furthermore this population of Mtb, which also showed reduced DNA repair activity, would result in selection and stabilization of spontaneous mutations in drug target genes, causing selection of a MDR strain in the presence of drug pressures. Efflux pump such as drrA may play a significant role in increasing fitness of low level drug resistant cells and assist in survival of Mtb till acquisition of drug resistant mutations with least fitness cost. PMID:23355892

Chatterjee, Anirvan; Saranath, Dhananjaya; Bhatter, Purva; Mistry, Nerges

2013-01-23

343

Electrical Resistivity and Induced Polarization as Tools for Mapping Near-Surface Weathered Hydrocarbon Bodies  

NASA Astrophysics Data System (ADS)

Induced polarization (IP) and electrical resistivity (ER) surveys were conducted at two legacy oil refinery sites in central Alberta during the fall of 2005 and summer of 2006. The first site had areas of near surface weathered hydrocarbons, and the second site had areas of saline soil and groundwater and areas of weathered hydrocarbons. The conductive saline environment of the second site posed significant challenges for the IP investigation. At the both sites, ER imaged weathered hydrocarbon bodies as resistive anomalies above background values. IP inversions yielded high values of chargeability at the boundaries of the resistive hydrocarbon bodies. At the second site, a resistivity high was associated with a change in subsurface lithology. Unlike the anomalies resulting from weathered hydrocarbons, there was no corresponding increase in chargeability associated with the high resistivity due to the lithology change. The results from these two surveys indicate that a combination of ER and IP is an effective tool for both mapping weathered hydrocarbons and in differentiating between resistivity increases associated with near surface hydrocarbons and resistivity increases due to subsurface lithology.

MacDonald, J.; Forte, S.; Bentley, L.

2006-12-01

344

Electrical Transport in Charge-Ordered Fe2OBO3: Resistive Switching and Pressure Effects  

SciTech Connect

The pressure-temperature-electric field phase diagram of Fe{sub 2}OBO{sub 3} is studied under ambient and high pressure using resistivity and thermoelectric power measurements. The onset of the incommensurate charge order at T{sub CO} = 340 K does not depend on pressure up to at least 2 GPa. The temperature of the transition to the commensurate charge order is increased by {approx}10 K/GPa. High pressure stabilizes the commensurate phase. We find evidence for resistive switching in the incommensurate phase, which may be linked to the dynamics of the charge-order domain boundaries.

Akrap, A. [Institut de Physique de la Matiere Complexe; Angst, M [Institut fur Festkorperforschung; Khalifah, Peter [Brookhaven National Laboratory (BNL); Mandrus, D. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Sales, Brian C [ORNL; Forro, Laszlo [Institut de Physique de la Matiere Complexe

2010-01-01

345

Electrical resistivity of the liquid phase of vesicular suspensions prepared by different methods  

NASA Astrophysics Data System (ADS)

Giant lipid vesicles are obtained mainly by two methods of formation: (i) electroformation and (ii) gentle hydration (spontaneous swelling). Very often the electoformation is carried out in experimental cells consisting of indium-tin oxide (ITO) coated plates as electrodes and various polymer spacers. In the present work, the influence of the ITO coatings and the polymer spacers on the electrical resistivity of the liquid medium of electroformed vesicle suspensions is examined by means of electrochemical impedance spectroscopy (EIS). Our study is intended to point out possible implications of the electroformation method, especially in cases when phenomena, related to electric properties of the vesicle membranes, are investigated.

Vitkova, V.; Antonova, K.; Popkirov, G.; Mitov, M. D.; Ermakov, Yu A.; Bivas, I.

2010-11-01

346

FAST TRACK COMMUNICATION: Rapid formation of electric field profiles in repetitively pulsed high-voltage high-pressure nanosecond discharges  

Microsoft Academic Search

Rapid formation of electric field profiles has been observed directly for the first time in nanosecond narrow-gap parallel-plate discharges at near-atmospheric pressure. The plasmas examined here are of hydrogen, and the field measurement is based on coherent Raman scattering (CRS) by hydrogen molecules. Combined with the observation of spatio-temporal light emission profiles by a high speed camera, it has been

Tsuyohito Ito; Kazunobu Kobayashi; Uwe Czarnetzki; Satoshi Hamaguchi

2010-01-01

347

Association between markers of systemic inflammation, oxidative stress, lipid profiles, and insulin resistance in pregnant women  

PubMed Central

BACKGROUND Increased levels of pro-inflammatory factors, markers of oxidative stress and lipid profiles are known to be associated with several complications. The aim of this study was to determine the association of markers of systemic inflammation, oxidative stress and lipid profiles with insulin resistance in pregnant women in Kashan, Iran. METHODS In a cross-sectional study, serum high sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-?), fasting plasma glucose (FPG), serum insulin, 8-oxo-7, 8-dihydroguanine (8-oxo-G), total cholesterol, triglyceride, High density lipoprotein-cholesterol (HDL-cholesterol), and plasma total antioxidant capacity (TAC) were measured among 89 primigravida singleton pregnant women aged 18-30 years at 24-28 weeks of gestation. Pearson’s correlation and multiple linear regressions were used to assess their relationships with homeostatic model assessment of insulin resistance (HOMA-IR). RESULTS We found that among biochemical indicators of pregnant women, serum hs-CRP and total cholesterol levels were positively correlated with HOMA-IR (? = 0.05, P = 0.006 for hs-CRP and ? = 0.006, P = 0.006 for total cholesterol). These associations remained significant even after mutual effect of other biochemical indicators were controlled (? = 0.04, P = 0.01 for hs-CRP and ? = 0.007, P = 0.02 for total cholesterol). Further adjustment for body mass index made the association of hs-CRP and HOMA-IR disappeared; however, the relationship for total cholesterol remained statistically significant. CONCLUSION Our findings showed that serum total cholesterol is independently correlated with HOMA-IR score. Further studies are needed to confirm our findings.

Asemi, Zatollah; Jazayeri, Shima; Najafi, Mohammad; Samimi, Mansooreh; Shidfar, Farzad; Tabassi, Zohreh; Shahaboddin, MohamadEsmaeil; Esmaillzadeh, Ahmad

2013-01-01

348

Use of Vitek 2 Antimicrobial Susceptibility Profile To Identify mecC in Methicillin-Resistant Staphylococcus aureus  

PubMed Central

The emergence of mecC methicillin-resistant Staphylococcus aureus (MRSA) poses a diagnostic challenge for clinical microbiology laboratories. Using the Vitek 2 system, we tested a panel of 896 Staphylococcus aureus isolates and found that an oxacillin-sensitive/cefoxitin-resistant profile had a sensitivity of 88.7% and a specificity of 99.5% for the identification of mecC MRSA isolates. The presence of the mecC gene, determined by bacterial whole-genome sequencing, was used as the gold standard. This profile could provide a zero-cost screening method for identification of mecC-positive MRSA strains.

Cartwright, Edward J. P.; Paterson, Gavin K.; Raven, Kathy E.; Harrison, Ewan M.; Gouliouris, Theodore; Kearns, Angela; Pichon, Bruno; Edwards, Giles; Skov, Robert L.; Larsen, Anders R.; Holmes, Mark A.; Parkhill, Julian; Peacock, Sharon J.

2013-01-01

349

A high temperature cell for simultaneous electrical resistance and neutron diffraction measurements.  

PubMed

An in situ cell that allows the electrical resistance of a sample pellet to be measured while performing neutron diffraction experiments has been developed at the ISIS pulsed neutron source. The sample is held between two spring loaded platinum electrodes embedded in a boron nitride clamp assembly with the resistance measured using the four-probe method. An outer quartz glass jacket allows the atmosphere within the sample enclosure to be controlled, and the entire device can be accommodated within a standard ISIS neutron furnace for measurements at temperatures up to 1270 K. The operation of this cell is illustrated using data for the structural, magnetic, and electrical properties of chalcopyrite CuFeS(2) collected over the temperature range of 398-873 K on the Polaris powder diffractometer at ISIS. PMID:19044451

Engin, T E; Powell, A V; Haynes, R; Chowdhury, M A H; Goodway, C M; Done, R; Kirichek, O; Hull, S

2008-09-01

350

Anomalous behavior of the electrical resistivity of MnSi near the ferromagnetic phase transition  

SciTech Connect

The results of measuring the electrical resistivity of a MnSi single crystal near the ferromagnetic phase transition at atmospheric and high pressures are reported. In contrast to the previous works, compressed helium is used as a pressure-transferring medium. It is shown that the temperature derivative of the electrical resistivity has the form of sharp maximum on the phase-transition line over the entire its length. Moreover, the observed maxima have a fine structure exhibiting a pronounced shoulder at temperatures slightly higher (by approximately 0.5 K) than the peak temperature, which indicates the existence of nontrivial fluctuations in the paramagnetic phase of MnSi. This feature disappears at a pressure of about 0.35 GPa, which corresponds to the tricritical-point coordinate.

Petrova, A. E. [Russian Academy of Sciences, Institute for High Pressure Physics (Russian Federation); Bauer, E. D. [Los Alamos National Laboratory (United States); Krasnorussky, V. N.; Stishov, S. M. [Russian Academy of Sciences, Institute for High Pressure Physics (Russian Federation)], E-mail: sergei@hppi.troitsk.ru

2007-02-15

351

Noncontact technique for measuring the electrical resistivity and magnetic susceptibility of electrostatically levitated melts  

NASA Astrophysics Data System (ADS)

Over the last two decades the popularity of levitation methods for studying equilibrium and supercooled melts has increased steadily. Measurements of density, viscosity, surface tension, and atomic structure have become well established. In contrast, measurements of electrical resistivity and magnetic susceptibility of levitated melts have been very limited. To fill this void, we have combined the tunnel diode oscillator (TDO) technique with electrostatic levitation (ESL) to perform inductively coupled measurements on levitated melts. A description of the basic operating principles of the TDO and ESL will be given, as well as a description of the implementation and performance characteristics of this technique. Preliminary measurements of electrical resistivity in the solid and liquid state will be presented for samples of Zr, Si, and Ge, as well as the measurements of ferromagnetic transitions in Fe and Co based alloys.

Rustan, G. E.; Spyrison, N. S.; Kreyssig, A.; Prozorov, R.; Goldman, A. I.

2012-02-01

352

Electrical resistivity measurements of the chalcogenide spinel, CuIr2S4, under extreme conditions  

NASA Astrophysics Data System (ADS)

Electrical resistivity as a function of pressure will be investigated for the thiospinel compound, CuIr2S4, which exhibits a metal to insulator transition at high pressures. This study will corroborate existing experimental and theoretical work and is the first of its kind to perform high pressure electrical conductivity and insulating phase optical studies in the range of room temperature to liquid nitrogen temperature. In addition, the transport properties of adamantine semiconductors will be studied at high pressure. The resistivity measurements will be made using a pseudo four-wire probing technique, using an AC constant current source, to eliminate thermal noise in the connections, and a nanovoltmeter. The study is currently ongoing and results are still pending. Improvements made to a stepper motor control program and changes to the system used for optical studies will be presented.

Hanni, Mark

2006-10-01

353

Laboratory measurements of basalts electrical resistivity under deep oceanic crustal conditions  

NASA Astrophysics Data System (ADS)

For sixty years, electrical resistivity soundings have been used to explore geothermal resources in Iceland. They have generally revealed two zones of high electrical conductivity, one at shallow depths (Flovenz et al., 1985) and another at 10-30 km depth (Beblo and Björnsson, 1978). The interpretation of these conductive zones in terms of composition and in-situ physical conditions is often ambiguous, as various parameters can explain these observations like temperature, partial melting, change in minerals and type of pore fluid. Accurate interpretations of resistivity data needed for geothermal exploration require laboratory measurements of electrical conductivities performed on rock samples at different conditions. We present here a method to measure electrical conductivity of rocks under deep crustal conditions for oceanic crustal rock, i.e. at temperatures up to 600°C, confining pressures up to 200 MPa and pore fluid pressures up to 50 MPa. The method has been developed in a internally heated, gas pressure apparatus (Paterson press). Electrical conductivity is measured on large cylindrical samples (15 to 22 mm in diameter and 10 to 15 mm in length) in a two parallel electrodes geometry. Such experiments require that the fluid saturated sample is sleeved in an impermeable and deformable jacket serving to separate the confining pressure medium (high pressure argon) from the pore fluid saturated sample. At temperature above 200°C a metal sleeve must be used, although it induces high leakage currents that could affect electrical measurements. The leakage currents are reduced using addition of 2 guard-ring parallel electrodes (Glover, 1995). The electrical impedance of basalt has been measured over a frequency range from 10 -1 to 106 Hertz. Five different types of low porosity basalts were selected to cover a range in alteration grade, from albitic to granulite facies. Application of this method will provide data on electrical conductivity of fresh and altered saturated basalts at in-situ conditions. These data will facilitate the understanding of both transient electromagnetic and with magnetotelluric data together with logging data from oceanic crust. Beblo, M. and Björnsson, A. Magnetotelluric investigation of the lower crust and upper mantle beneath Iceland. Journal of Geophysics, 45, 1-16. 1978 Flovenz O.G., Georgsson L. S. and Arnason, Knutur. Resistivity Structure of the Upper Crust in Iceland. Journal of geophysical research, Vol.90 NO B12, Pages 10,136-10 150. 1985. Glover Paul W.J., Vine F.J.. Beyong KTB- Electrical Conductivity of the Deep Continental crust. Survey in Geophysics. Vol. 16, pages 47-62. 1995.

Violay, M. E.; Gibert, B.; Azais, P.; Pezard, P. A.; Flovenz, O. G.; Asmundsson, R.

2009-12-01

354

Magnetic Moment, Susceptibility, and Electrical Resistivity of Dilute Paramagnetic Palladium-Rare-Earth Alloys  

Microsoft Academic Search

The magnetic properties and low-temperature electrical resistivity are reported for dilute alloys of the Pd1-xRx system where R=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y, and x is generally 0.01 or less. Alloys with R=Ce, Gd, Dy, or Er are examined over a wide range of concentrations. The quantities measured were the magnetic

R. P. Guertin; H. C. Praddaude; S. Foner; E. J. McNiff; B. Barsoumian

1973-01-01

355

Electrical resistivity and magnetic investigations of the orthorhombic Tb(Ni, Cu)2 system  

Microsoft Academic Search

The orthorhombic Tb(Ni, Cu)2 and Gd(Ni, Cu)2 systems (CeCu2 structure) are closely similar according to electrical resistivity and magnetic results. The Tb(NixCu1-x)2 system presents a transition from antiferromagnetism (AF) for x <= 8% Ni to ferromagnetism (FM) for x > 8% Ni. The CeCu2 structure becomes unstable for x > 45% Ni. The AF samples show metamagnetism at 4.2 K

C. A. Poldy; E. Gratz

1978-01-01

356

Laser induced reversible change of electrical resistivity of CoSi2 thin film  

Microsoft Academic Search

Formation of thin crystalline layers of CoSi2 deposited by coevaporation of Co+Si mixtures on SiO2\\/Si substrates has been attained by a Q-switched YAG:Nd and CO2 lasers. Electrical and optical properties of the CoSi2 layers have been studied by simultaneous laser irradiation. It is shown that high quality resistive crystalline CoSi2 films can be obtained by treatment with CO2 laser radiation

M. Knite; A. Medvid; Y. Barloti; M. Silarays

1997-01-01

357

[Testing the electric resistance as an objective diagnostic test in dental pulp diseases].  

PubMed

The authors test by means of a measuring device of high precision the resistence of health or sick human pulpa, comparing it to them of gums, excluding in the same time the sensibility of the patient in question. The authors corroborate the obtained dates with clinical symptomatology and the histopathological photos, discussing the possibility of objective electrical test as an expedient in the diagnosis of pulpa-affections. PMID:137616

Constantin, I; Severineanu, V; Tudose, N

1976-01-01

358

Evaluation of landfill disposal boundary by means of electrical resistivity imaging  

Microsoft Academic Search

This paper deals with an employment of electrical resistivity imaging (ERI) for survey of leachate content on the waste disposal\\u000a site in Northern Israel. The research consisted of conducting ten ERI lines and drilling investigation wells. Data simulation\\u000a used a 2D EarthImager inversion program. Analysis of 2D ERI interpretation results shows that determination of the boundary\\u000a between the landfill body

Vladimir Frid; Gady Liskevich; Dmitriy Doudkinski; Nikolay Korostishevsky

2008-01-01

359

Size and temperature effects on the thermoelectric power and electrical resistivity of bismuth telluride thin films  

Microsoft Academic Search

Thermoelectric power and electrical resistivity measurements have been carried out as a function of temperature in the range 300-470 K on well-annealed thin films of Bi2Te3 of various thicknesses in the range 400-1900 Å. The films of a given thickness for both the measurements have been prepared simultaneously in a single evaporation so that the results of the thermoelectric power

V. Damodara Das; N. Soundararajan

1988-01-01

360

Electrical transport properties of TiCoSb half-Heusler phases that exhibit high resistivity  

Microsoft Academic Search

Electrical transport measurements have been performed on doped and undoped TiCoSb half-Heusler phases. The semiconducting properties are found to be more robust than those reported for MNiSn (M = Ti, Zr, Hf ). Undoped TiCoSb phases exhibit large n-type Seebeck coefficients and high resistivities that reach -500 µV K-1 at 300 K and ~1500 Omega cm at 4.2 K, respectively.

Y. Xia; V. Ponnambalam; S. Bhattacharya; A. L. Pope; S. J. Poon; T. M. Tritt

2001-01-01

361

Resistively-tapered-dipole electric-field probes up to 40 GHz  

Microsoft Academic Search

An electric-field probe for use as a transfer standard at frequencies up to 40 GHz is developed. The lower frequency cutoff is below 1 MHz. The design is based on the resistively tapered dipole (RTD) probes developed for frequencies up to 18 GHz. Those probes used 8-mm tapered dipoles. In this study, 6-mm, 4-mm, and 2-mm dipoles are used to

J. Randa; M. Kanda; R. D. Orr

1991-01-01

362

Measurement of the electrical resistance of aluminium samples in sulphuric acid solutions by optical interferometry techniques  

Microsoft Academic Search

Holographic interferometry was utilized for the first time to measure the electrical resistance of aluminium samples during the initial stage of anodization processes in aqueous solution without any physical contact. The anodization process (oxidation) of the aluminium samples was carried out chemically in different sulpheric acid concentrations (0.5 - 3.125% H2SO4) at room temperature. In the mean time, a method

Khaled Habib

2005-01-01

363

Measurement of the electrical resistance of aluminum samples by holographic interferometry  

Microsoft Academic Search

In the present investigation, holographic interferometry was utilized for the first time to measure the electrical resistance of aluminum samples during the initial stage of anodization processes in aqueous solution without any physical contact. The anodization process (oxidation) of the aluminum samples was carried out chemically in different sulpheric acid concentrations (0.5 - 3.125% H2SO4) at room temperature. In the

Khaled J. Habib

1998-01-01

364

Electrical Resistivities and Magnetic Properties of Amorphous AI-Y-Ni Alloys  

NASA Astrophysics Data System (ADS)

In this study, electrical and magnetic properties of amorphous Al85Y5Ni10, Al85Y9Ni6, Al85Y10Ni5 and Al85Y11Ni9 alloys were measured. The resistivities of the samples increased with increasing Y content in the amorphous matrix. Magnetic properties of the samples were not observed in magnetic field up to 8000 A/m.

Alver, Ü.; Kerli, S.; Gö?ebakan, M.

2007-04-01

365

Density Muon Radiography of Soufrière of Guadeloupe Volcano: Comparison with Geological, Electrical Resistivity and Seismic data.  

NASA Astrophysics Data System (ADS)

We present density radiographies obtained for the Soufrière of Guadeloupe lava dome, both in the North-South and East-West planes. These radiographies reveal the highly heterogeneous density structure of the volcano, with low-density regions corresponding to recognized hydrothermally altered areas. The main structures observed in the density radiographies correlate with anomalies in electrical resistivity cross-sections and seismic velocity model.

Gibert, D.; Lesparre, N.; Marteau, J.; Komorowski, J.-C.; Nicollin, F.; Coutant, O.; Carbone, D.; Kergosien, B.; Rolland, P.

2012-04-01

366

An investigation of structural phase transformation and electrical resistivity in Ta films  

Microsoft Academic Search

In this work, we report the effect of substrate, film thickness and sputter pressure on the phase transformation and electrical resistivity in tantalum (Ta) films. The films were grown on Si(100) substrates with native oxides in place and glass substrates by varying the film thickness (t) and pressure of the working gas (pAr). X-ray diffraction (XRD) analysis showed that the

A. Javed; Ji-Bing Sun

2010-01-01

367

Interface in mechanically fastened steel joint, studied by contact electrical resistance measurement  

NASA Astrophysics Data System (ADS)

A steel-to-steel joint obtained by mechanical fastening at a compressive stress of 7% (or less) of the yield strength was found to exhibit irreversible changes in the contact electrical resistance upon repeated fastening (loading) and unfastening (unloading). These changes occurred even after many cycles of fastening and unfastening, although the changes were more severe during the initial few cycles. They were primarily due to plastic deformation at asperities.

Luo, Xiangcheng; Chung, D. D. L.

2000-02-01

368

A flowing solvent reactor for coal liquefaction with direct electrical resistance heating  

Microsoft Academic Search

A flowing solvent reactor for coal liquefaction has been developed, which uses direct electrical resistance heating of the reactor tube wall to achieve rapid, controllable heating. A computerized control system previously developed for a wire-mesh pyrolysis apparatus is used for temperature control; heating rates between 0.1 and 10 K\\/s, peak temperatures up to 450 °C, and isothermal holding times from

Jon Gibbins; Rafael Kandiyoti

1991-01-01

369

Electrical resistivity of Cu and Ag-based dilute alloys at low temperatures  

Microsoft Academic Search

The matrix elements of the electron-phonon interaction are calculated by the APW method for copper and silver. The matrix elements of the electron-impurity interaction are also evaluated by the KKR method. On the basis of these matrix elements the authors have discussed the low-temperature electrical resistivity of the nominally pure samples of copper and silver and their dilute alloys. The

J. Yamashita; S. Asano

1986-01-01

370

Electrical resistivity of nanocrystals in Fe-Al-Ga-P-B-Si-Cu alloy  

NASA Astrophysics Data System (ADS)

In new supercooled Fe74Al4Ga2P11B4Si4Cu1 alloy the 10nm size ?-Fe(Si) nanocrystals are precipitated. Thermal stability is analyzed by the electron transport and magnetization measurements. Temperature variation of electrical resistivity of nanocrystals is determined and discussed for alloys with different initial crystalline fraction. Possible mechanism inhibiting the grain growth is presented.

Pekala, K.; K.; Ja?kiewicz, P.; Nowi?ski, J. L.; Pekala, M.

2003-05-01

371

Effect of epoxy resin coating on electric resistance and environment-proofing character of woodceramics  

Microsoft Academic Search

In order to evaluate the reliability of woodceramics when applied to snow heaters, the effect of an epoxy resin coating on the electric resistance and environment-proofing characteristics has been experimentally investigated by the use of heat-cycle tests and high temperature-exposure tests. It is found that in order to obtain a reliable coating on woodceramics, one must use a resin having

T. Azuma; M. Otsuka; K. Hata; J. Tsuji; T. Okabe; M. Takayama

1999-01-01

372

Erwinia amylovora modifies phenolic profiles of susceptible and resistant apple through its type III secretion system.  

PubMed

Fire blight is a disease affecting Maloideae caused by the necrogenic bacterium Erwinia amylovora, which requires the type III protein secretion system (TTSS) for pathogenicity. Profiles of methanol-extractable leaf phenolics of two apple (Malus x domestica) genotypes with contrasting susceptibility to this disease were analyzed by HPLC after infection. Some qualitative differences were recorded between the constitutive compositions of the two genotypes but in both of them dihydrochalcones accounted for more than 90% of total phenolics. Principal component analysis separated leaves inoculated with a virulent wild-type strain from those inoculated with a non-pathogenic TTSS-defective mutant or with water. The changes in levels of the various groups of phenolics in response to the virulent bacterium were similar between the two genotypes, with a significant decrease of dihydrochalcones and a significant increase of hydroxycinnamate derivatives. Differences between genotypes were, however, recorded in amplitude and kinetic of variation in these groups. Occurrence of oxidation and polymerization reactions is proposed, based on the browning process of infected tissues, but whether some by-products act in defense as toxic compounds remain to be tested. Among direct antibacterial constitutive compounds present in apple leaves, the dihydrochalcone phloretin only was found at levels close to lethal concentrations in both genotypes. However, E. amylovora exhibited the ability to stabilize this compound at sublethal levels even in the resistant apple, rejecting the hypothesis of its involvement in the resistance of this genotype. PMID:18275458

Pontais, Isabelle; Treutter, Dieter; Paulin, Jean-Pierre; Brisset, Marie-Noëlle

2008-03-01

373

Virulence Genes and Antimicrobial Resistance Profiles of Pasteurella multocida Strains Isolated from Rabbits in Brazil  

PubMed Central

Pasteurella multocida is responsible for a wide range of diseases in domestic animals. In rabbits, the agent is related to nasal discharge, pneumonia, otitis media, pyometra, orchitis, abscess, and septicemia. One hundred and forty rabbits with respiratory diseases from four rabbitries in São Paulo State, Brazil were evaluated for the detection of P. multocida in their nasal cavities. A total of twenty-nine animals were positive to P. multocida isolation, and 46 strains were selected and characterized by means of biochemical tests and PCR. P. multocida strains were tested for capsular type, virulence genes, and resistance profile. A total of 45.6% (21/46) of isolates belonged to capsular type A, and 54.34% (25/46) of the isolates were untypeable. None of the strains harboured toxA or pfhA genes. The frequency of the other twenty genes tested was variable, and the data generated was used to build a dendrogram, showing the relatedness of strains, which were clustered according to origin. Resistance revealed to be more common against sulfonamides and cotrimoxazole, followed by erythromycin, penicillin, and amoxicillin.

Ferreira, Thais Sebastiana Porfida; Felizardo, Maria Roberta; Sena de Gobbi, Debora Dirani; Gomes, Cleise Ribeiro; Nogueira Filsner, Pedro Henrique de Lima; Moreno, Marina; Paixao, Renata; Pereira, Jucelia de Jesus; Micke Moreno, Andrea

2012-01-01

374

Cellular fatty acid composition, soluble-protein profile, and antimicrobial resistance pattern of Eubacterium lentum.  

PubMed

Phenotypic heterogeneity among isolates of Eubacterium lentum has been recognized for many years. To better delineate their taxonomic relatedness, 29 clinical isolates of E. lentum were examined for soluble-protein content, cellular fatty acid profile, and antimicrobial resistance pattern in order to ascertain whether differences in these characteristics could be correlated with differences in biochemical activities. Among 29 isolates we could identify 6 that were different from all the others. These strains were coccobacilli with translucent colonies; they were catalase and H2S negative, not fluorescent under UV light, and susceptible to beta-lactam drugs; growth was not stimulated by arginine; and fatty acid analysis revealed the presence of straight-chain fatty acids. The remainder of the strains, including the type species, were pleomorphic bacilli with speckled colonies and were catalase and H2S positive; all but two were fluorescent under UV light; they were resistant to beta-lactam antibiotics; growth was greatly stimulated by arginine; and they demonstrated saturated branched-chain fatty acids. Our data suggest that E. lentum can be further differentiated into different types. PMID:9508307

Mosca, A; Summanen, P; Finegold, S M; De Michele, G; Miragliotta, G

1998-03-01

375

Interpretation of a dipole-dipole electrical resistivity survey, Colado geothermal area, Pershing County, Nevada  

SciTech Connect

An electrical resistivity survey in the Colado geothermal area, Pershing County, Nevada has defined areas of low resistivity on each of five lines surveyed. Some of these areas appear to be fault controlled. Thermal fluids encountered in several drill holes support the assumption that the hot fluids may be associated with areas of low resistivity. The evidence of faulting as interpreted from modeling of the observed resistivity data is therefore particularly significant since these structures may be the conduits for the thermal fluids. Sub-allurial fault zones are interpreted to occur between stations 0 to 5 NW on Line D and on Line A between stations 4 NW and 4 SE. Fault zones are also interpreted on Line C near stations 1 NW, 1 SE, and 3 SE, and on Line E between stations 2 to 4 NW and near 1 SE. No faulting is evident under the alluvial cover on the southwest end of Line B. A deep conductive zone is noted within the mountain range on two resistivity lines. There is no definite indication that thermal fluids are associated with this resistivity feature.

Mackelprang, C.E.

1980-09-01

376

Combined Macroscopic Invasion Percolation and Continuum Modeling of Electrical Resistivity Measurements in Unsaturated Media  

NASA Astrophysics Data System (ADS)

When coupled with unsaturated flow models, electrical resistivity techniques (including tomography) offer the promise of non-intrusive characterization of moisture within the unsaturated zone. Most unsaturated flow models (e.g., Richards' equation) are continuum models that are incapable of reproducing the complicated aqueous- phase structure observed in many field and laboratory experiments. This heterogeneous distribution of moisture contributes to highly heterogeneous distributions of electrical conductivity (EC) within unsaturated materials. We explore the influence of this heterogeneity using an experimentally verified modeling study. We simulate the evolution of aqueous phase structures using a macroscopic invasion percolation (MIP) model that accurately reproduces the complicated aqueous phase structures that arise within unsaturated porous media. Unlike traditional invasion percolation (IP) models which specify individual pore throats and necks, MIP models use an up-scaled blocks that are defined by a local threshold spanning (capillary) pressure. Block moisture contents are then mapped to block-specific EC values using the constitutive model of Mualem and Friedman (1991). Resulting heterogeneous EC fields are then used in a finite-difference model to simulate resistivity measurements. This approach is experimentally verified by simulations of laboratory measurements of electrical resistivity in layered samples at various moisture contents. Broader implications are explored through additional simulations.

Holt, R. M.

2007-05-01

377

Microgravity conditions and electrical resistivity of liquid alloys with critical mixing  

SciTech Connect

The phenomena of two-liquid phase separations are significantly influenced by the gravity on the ground because of the difference in the densities of the constituent components, particularly, in the case of liquid alloys with critical mixing. In this paper, experimental techniques and results ar reported for the measurements of the electrical resistivity for typical liquid alloys with critical mixing, such as Bi-Ga, under microgravity by the use of a rocket S520-19 belonging to ISAS (Institute of Space and Astronautical Science, Japan). It was found that the temperature coefficient of the electrical resistivity, on cooling of the homogeneous liquid phase, increases with the approach to the critical temperature. This trend under microgravity by the rocket experiment is more pronounced compared to the trend of the reference experiment on the ground. In addition, the supercooling of homogeneous liquids under microgravity is larger than that on the ground. These differences are explained by the difference in the degree of the growth of concentration fluctuations, the concentration fluctuations are far greater under microgravity than on the ground. Therefore, it is found to be very important to study the process and the critical phenomena of two-liquid phase separations under microgravity. Measurement of electrical resistivity is an effective method to obtain information about the process, the critical phenomena, and the supercooling of two-liquid phase separations in liquid alloys with critical mixing.

Itami, T.; Masaki, T. [Hokkaido Univ., Sapporo (Japan). Dept. of Chemistry; Kuribayashi, K.; Sato, E.; Hinada, M.; Yamashita, M. [Inst. of Space and Astronautical Science, Sagamihara (Japan); Kawasaki, K. [Nissan Motor Company, Ltd., Tokyo (Japan)

1997-03-01

378

A method to investigate the electron scattering characteristics of ultrathin metallic films by in situ electrical resistance measurements.  

PubMed

In this article, a method to measure the electrical resistivity/conductivity of metallic thin films during layer growth on specific underlayers is described. The in situ monitoring of an underlayer electrical resistance, its change upon the incoming of new material atoms/molecules, and the growth of a new layer are presented. The method is easy to implement and allows obtaining in situ experimental curves of electrical resistivity dependence upon film thickness with a subatomic resolution, providing insight in film growth microstructure characteristics, specular/diffuse electron scattering surfaces, and optimum film thicknesses. PMID:19655967

Trindade, I G; Fermento, R; Leitão, D; Sousa, J B

2009-07-01

379

A method to investigate the electron scattering characteristics of ultrathin metallic films by in situ electrical resistance measurements  

SciTech Connect

In this article, a method to measure the electrical resistivity/conductivity of metallic thin films during layer growth on specific underlayers is described. The in situ monitoring of an underlayer electrical resistance, its change upon the incoming of new material atoms/molecules, and the growth of a new layer are presented. The method is easy to implement and allows obtaining in situ experimental curves of electrical resistivity dependence upon film thickness with a subatomic resolution, providing insight in film growth microstructure characteristics, specular/diffuse electron scattering surfaces, and optimum film thicknesses.

Trindade, I. G.; Sousa, J. B. [IFIMUP and IN, Rua do campo Alegre, 687, 4169-007 Porto (Portugal); Department of Physics, FCUP, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Fermento, R. [Instituto de Microelectronica de Madrid, Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain); Leitao, D. [IFIMUP and IN, Rua do campo Alegre, 687, 4169-007 Porto (Portugal)

2009-07-15

380

Electrical resistivity measurements on manganese oxides with layer and tunnel structures: Birnessites, todorokites, and cryptomelanes  

SciTech Connect

Direct-current measurements were used to determine the electrical resistivities of several manganese oxide materials having either layered or tunnel structures. Birnessite (Na-OL-1, OL=octahedral layer) consists of layers of edge- and corner-sharing Mn{sub 6} octahedral units with Na{sup +} in the interlayer regions. Todorokite and cryptomelane (Mg-OMS-1 and K-OMS-2, respectively, OMS = octahedral molecular sieve) are similarly built from MnO{sub 6} units, but in these systems the octahedral join to form 6.9 and 4.6 {Angstrom} tunnels occupied by Mg{sup 2+} and K{sup +}, respectively. Resistivities were also measured for OL-1, OMS-1, and OMS-2 materials in which (a) cation exchange was carried out at layer and tunnel sites or (b) isomorphous subsititution for Mn was performed by doping small amounts of foreign cations into the manganese oxide framework. Four probe measurements on pressed pellets reveal that OL-1 and OMS-1 materials have resistivities on the order of 10{sup 5}-10{sup 6} {Omega}cm at 298 K. OMS-2 materials have resistivities on the order of 10{sup 5}-10{sup 6} {Omega} cm at 298 K. Variable-temperature measurements establish a general pattern of increasing resistivity with decreasing temperature. However, between 153 and 293 K, OL-1 and OMS-1 materials do not obey a simple exponential variation of resistivity and temperature. By contrast, OMS-2 samples follow the Arrhenius relationship over a comparable temperature range. Activation energies for the conductivity OMS-2 materials were calculated to be in the range 0.5-0.6 eV. Solid-state voltammetry was used to determine the electrical resistance of OMS-1 and OMS-2 samples at higher temperatures from 298 to 673 K. A general exponential decrease in resistance with increasing temperature was observed for both classes of materials. Ac resistivity measurements show similar trends to dc resistivity data. 36 refs., 8 figs., 3 tabs.

De Guzman, R.N.; Awaluddin, A.; Shen, Y.F. [and others

1995-07-01

381

Effects of ACE Inhibitors on Insulin Resistance andLipid Profile in Children with Metabolic Syndrome.  

PubMed

Objective: The aim of this study was to evaluate the effects of using ACE inhibitors on insulin resistance, glucose metabolism, body fat composition, and lipid profile in children over 10 years of age with obesity-associated metabolic syndrome (MS).Methods: A total of 53 children with MS, who had been followed for at least one year were included in the study. The sample was divided into two groups: Group 1-30 obese children (13 female, 17 male) who were not using an ACE inhibitor and Group 2-23 obese children (13 female, 10 male) who were using an ACE inhibitor. Anthropometric and laboratory dataobtained at baseline and at the 3rd, 6th, and 12th months of follow-up were compared in the two groups.Results: Comparison of the data in the two groups at 3rd, 6th, and 12th months revealed no statistically significant differences in terms of weight standard deviation score (SDS), body mass index SDS, weight for height percentile, body fat percentage, and very low-density lipoprotein (VLDL)values. However, there were statistically significant differences in mean glucose and insulin levels, homeostasis model assessment for insulin resistance, LDL and high-density lipoprotein values, and highly significant differences in mean triglyceride values.Conclusions: The positive effects of ACE inhibitor drugs, particularly on hypertriglyceridemia and insulin resistance, might bring them forth as first-line drugs in the treatment of obese and hypertensive children. Randomized, controlled, double-blind, and long-term studies are needed for a definitive conclusion. PMID:24072084

Bitkin, Eda Celebi; Boyraz, Mehmet; Ta?k?n, Necati; Akçay, Arzu; Ulucan, Korkut; Akyol, Mehmet Bedir; Akçay, Teoman

2013-09-10

382

Evaluation of landfill disposal boundary by means of electrical resistivity imaging  

NASA Astrophysics Data System (ADS)

This paper deals with an employment of electrical resistivity imaging (ERI) for survey of leachate content on the waste disposal site in Northern Israel. The research consisted of conducting ten ERI lines and drilling investigation wells. Data simulation used a 2D EarthImager inversion program. Analysis of 2D ERI interpretation results shows that determination of the boundary between the landfill body bottom intensively saturated with leachates and underlying layers of highly water saturated fat nonconsolidated clays presents a challenge. However, statistical analysis of ERI data indicates that standard deviation and confidence interval of a set of resistivity data measured in the landfill body are significantly larger than those in underlying clays. Moreover, maximum changes of these parameters are found on the boundary between landfill body and underlying soil, thus reflecting natural differences in scattering of resistivity data measured in these two objects.

Frid, Vladimir; Liskevich, Gady; Doudkinski, Dmitriy; Korostishevsky, Nikolay

2008-02-01

383

Electrical resistivity and absolute thermoelectric power of liquid indium-nickel-manganese ternary alloys  

NASA Astrophysics Data System (ADS)

The electrical resistivity and the absolute thermopower of In-Ni-Mn liquid ternary alloys have been measured as functions of temperature and of concentration. The transition metal composition was held constant and, starting from the indium-nickel eutectic, we substituted manganese for nickel up to 50 atomic per cent manganese (0953-8984/11/15/010/img1 with x up to 0.5). The experimental transport properties for the ternary alloys are completely different from what could be expected from an interpolation between the resistivities of the two binary systems In-Ni and In-Mn that we measured earlier. Therefore this system is particularly suitable for testing the extended Faber-Ziman theory. Experimentally it is found that the resistivity decreases and that the thermopower increases strongly as functions of the manganese composition in the ternary system. These data are discussed and interpreted qualitatively, taking into account the electronic structure of the ternary alloy.

Auchet, J.; Rhazi, A.; Gasser, J. G.

1999-04-01

384

Chilling resistance of Phaseolus vulgaris and Brassica oleracea under a high-intensity electric field.  

PubMed

An electric field may have different effects on plant metabolism depending upon its application style and density, and environmental conditions. The effects of an electric field, low temperature, and their combinations on tissue vitality and some physiological variables regarding antioxidant responses of "bean" (Phaseolus vulgaris L. cv. Gina) and "cole" (Brassica oleracea L. cv. Acephale) leaves were studied. Fifteen-day-old seedlings were exposed to an electric field (100 kV m(-1)) for 10 or 40 min prior to cold treatment. In both plant leaves, cold application caused statistically significant increments in total soluble protein levels and selected antioxidant enzyme activities such as catalase, peroxidase and superoxide dismutase activities. However, tissue vitality and H2O2 levels did not change in "cole", while tissue vitality decreased and H2O2 levels increased in "bean". Electric field application itself did not cause any significant changes in "bean" and "cole" leaves. On the other hand, 40 min electric field application increased the deteriorative effect of cold in both plant species, while 10 min electric field augmented the chilling resistance by increasing the tissue vitality and antioxidant enzyme activities resulting in decreased H2O2 levels. PMID:20653240

Cakmak, Turgay; Dumlupinar, Rahmi; Erdal, Serkan

385

Noncontact technique for measuring the electrical resistivity and magnetic susceptibility of electrostatically levitated materials.  

PubMed

We describe the development of a new method for measuring the electrical resistivity and magnetic susceptibility of high temperature liquids and solids. The technique combines a tunnel diode oscillator with an electrostatic levitation furnace to perform noncontact measurements on spherical samples 2-3 mm in diameter. The tank circuit of the oscillator is inductively coupled to the sample, and measurements of the oscillator frequency as a function of sample temperature can be translated into changes in the sample's electrical resistivity and magnetic susceptibility. Particular emphasis is given on the need to improve the positional stability of the levitated samples, as well as the need to stabilize the temperature of the measurement coil. To demonstrate the validity of the technique, measurements have been performed on solid spheres of pure zirconium and low-carbon steel. In the case of zirconium, while absolute values of the resistivity were not determined, the temperature dependence of the resistivity was measured over the range of 640-1770 K and found to be in good agreement with literature data. In the case of low-carbon steel, the ferromagnetic-paramagnetic transition was clearly observable and, when combined with thermal data, appears to occur simultaneously with the solid-solid structural transition. PMID:23126782

Rustan, G E; Spyrison, N S; Kreyssig, A; Prozorov, R; Goldman, A I

2012-10-01

386

Noncontact technique for measuring the electrical resistivity and magnetic susceptibility of electrostatically levitated materials  

NASA Astrophysics Data System (ADS)

We describe the development of a new method for measuring the electrical resistivity and magnetic susceptibility of high temperature liquids and solids. The technique combines a tunnel diode oscillator with an electrostatic levitation furnace to perform noncontact measurements on spherical samples 2-3 mm in diameter. The tank circuit of the oscillator is inductively coupled to the sample, and measurements of the oscillator frequency as a function of sample temperature can be translated into changes in the sample's electrical resistivity and magnetic susceptibility. Particular emphasis is given on the need to improve the positional stability of the levitated samples, as well as the need to stabilize the temperature of the measurement coil. To demonstrate the validity of the technique, measurements have been performed on solid spheres of pure zirconium and low-carbon steel. In the case of zirconium, while absolute values of the resistivity were not determined, the temperature dependence of the resistivity was measured over the range of 640-1770 K and found to be in good agreement with literature data. In the case of low-carbon steel, the ferromagnetic-paramagnetic transition was clearly observable and, when combined with thermal data, appears to occur simultaneously with the solid-solid structural transition.

Rustan, G. E.; Spyrison, N. S.; Kreyssig, A.; Prozorov, R.; Goldman, A. I.

2012-10-01

387

The effects of dopants on the electrical resistivity in lead magnesium niobate multilayer ceramic capacitors  

SciTech Connect

Electrical resistivity studies were performed on multilayer ceramic capacitors (MLC) based on lead magnesium niobate and containing dopants of lead titanate, lead zinc niobate, and lead cobalt niobate. The results showed that lead titanate and/or lead zinc niobate had no effect on the electrical resistivity while lead cobalt niobate decreased the resistivity. In samples without lead cobalt niobate, we observed a conduction mechanism with an activation energy of --1 eV, which is commonly observed in barium titanate based dielectrics. This is attributed to ionic conduction via the motion of oxygen vacancies. The increase in conductivity (or decrease in resistivity) resulting from the addition of lead cobalt niobate was rationalized as due to electronic conduction through charge hopping among the cations. This conduction mechanism was characterized by an activation energy of --0.5 eV. Since the activation energy associated with the long-term failure was previously determined by a matrix of temperature and voltage accelerated life tests to be -- 1 eV, they conclude that conduction through charge hopping is not affecting the long-term reliability of these devices.

Chang, D.D.; Ling, H.C. (AT and T Bell Labs., Princeton, NJ (US))

1989-06-01

388

Interplay between interaction and chiral anomaly: Anisotropy in the electrical resistivity of interacting Weyl metals  

NASA Astrophysics Data System (ADS)

We predict that long-range interactions give rise to anisotropy in the electrical resistivity of Weyl metals at low temperatures, where the electrical resistivity becomes much reduced when electric fields are applied to the direction of the momentum vector to connect two paired Weyl points. Performing the renormalization group analysis, we find that the distance between two Weyl points becomes enhanced logarithmically at low temperatures although the coupling constant of such interactions vanishes inverse-logarithmically. Considering the Adler-Bell-Jackiw anomaly, scattering between these two Weyl points becomes suppressed to increase electrical conductivity in the “longitudinal” direction, counter intuitive in the respect that interactions are expected to reduce metallicity. We also propose that the anomalous contribution in the Hall effect shows the logarithmic enhancement as a function of temperature, originating from the fact that the anomalous Hall coefficient turns out to be proportional to the distance between two paired Weyl points. Correlations with topological constraints allow unexpected and exotic transport properties.

Jho, Yong-Soo; Kim, Ki-Seok

2013-05-01

389

Electrical Resistivity Monitoring for Leachate Distribution at Two Foot-and-Mouth- Disease (FMD) Burial Sites  

NASA Astrophysics Data System (ADS)

The main objective of this study was to provide the basic information on leachate distribution with time changes through the electrical resistivity monitoring for a certain period of time in the Foot-and-Mouth-Disease (FMD) burial facilities which is needed to prevent further soil and groundwater contamination and to build an effective plan for stabilization of the burial site. In this study, dipole-dipoles surveys were carried out around two FMD burial sites in Iceon-si, Gyeonggi-do. The FMD burial facility installed at Daewall-myeon is consists of one block but, at Yul-myeon, it is divided into 2 blocks named A and B blocks. Dipole-Dipole surveys with 8 lines at Yul-myeon and 3 lines at Daewall-myeon were carried out. The observed leachate distribution along survey lines was not clearly evident as time passes at Daewall-myeon site, but, at Yul-myeon site, the leachate distribution around the survey lines showed a decrease of resistivity around the burial facility. At and around A and B blocks of Yul-myeon site, interpretations of the survey data show low resistivity zones below 10 ?m from a depth 3 m to 10 m and such low resistivity zones of the A block are thicker than the B block by about 5~10 m. From the geochemical data and resistivity survey at two FMD burial sites, it is inferred that the groundwater within a 50-meter radius around burial facilities of the Yul-myeon site are contaminated by leachate. The general resistivity distribution around the burial site is seemed affected by the leachate with high electrical conductivity. The detail distribution patterns can be explained by local distributions of soil and weathered rocks and associated leachate flow. This subject is supported by Brain Korea 21 and Korea Ministry of Environment as 'The GAIA Project (173-092-009)'.

Lee, S.; Kaown, D.; Lee, K.; Leem, K.; Ko, K.

2011-12-01

390

Prevalence and antibiotic resistance profile of mercury-resistant oral bacteria from children with and without mercury amalgam fillings  

Microsoft Academic Search

Genes encoding resistance to mercury and to antibiotics are often carried on the same mobile genetic element and so it is possible that mercury-containing dental materials may select for bacteria resistant to mercury and to antibiotics. The main aim of this study was to determine whether the prevalence of Hg-resistant oral bacteria was greater in children with mercury amalgam fillings

R. Pike; V. Lucas; P. Stapleton; M. S. Gilthorpe; G. Roberts; R. Rowbury; H. Richards; P. Mullany; M. Wilson

2002-01-01

391

Impact of restricted amoxicillin/clavulanic acid use on Escherichia coli resistance--antibiotic DU90% profiles with bacterial resistance rates: a visual presentation.  

PubMed

High use of amoxicillin/clavulanic acid (AMC) at the University Hospital Osijek (Croatia) contributed to high rates of resistance in Enterobacteriaceae, in particular Escherichia coli (50%). Thus, in order to decrease bacterial resistance, AMC use was restricted. We present results of the restriction on resistance amongst antibiotics accounting for 90% of antibiotic use [drug utilisation 90% (DU90%)]. Data were analysed on antibiotic use and microbiological susceptibility of E. coli during two 9-month periods, before and after the restriction of AMC use. Drug use was presented as numbers of defined daily doses (DDDs) and DDDs/100 bed-days. Resistance of E. coli to antibiotics was presented as percentages of isolated strains in the DU90% segment. Use of AMC was 16 DDDs/100 bed-days or 30% of all antibiotics before the intervention. Use of AMC fell to 2 DDDs/100 bed-days or 4% after the intervention, and resistance of E. coli fell from 37% to 11%. In conclusion, restricted use of AMC resulted in a significant decrease of E. coli resistance. DU90% resistance profiles are simple and useful tools in highlighting problems in antibiotic use and resistance but may also be useful in long-term follow-up of antibiotic policy. PMID:20688486

Mimica Matanovic, Suzana; Bergman, Ulf; Vukovic, Dubravka; Wettermark, Björn; Vlahovic-Palcevski, Vera

2010-08-05

392

Association of multiple-antibiotic-resistance profiles with point and nonpoint sources of Escherichia coli in Apalachicola Bay.  

PubMed

A total of 765 Escherichia coli isolates from point and nonpoint sources were collected from the Apalachicola National Estuarine Research Reserve, and their multiple-antibiotic-resistance (MAR) profiles were determined with 10 antibiotics. E. coli isolates from point sources showed significantly greater resistance (P < 0.05) to antibiotics and higher MAR indices than isolates from nonpoint sources. Specifically, 65 different resistance patterns were observed among point source isolates, compared to 32 among nonpoint source isolates. Examples of this contrast in MAR profiles included percentages of isolates with resistance to chlortetracycline-sulfathiazole of 33.7% and to chlortetracycline-penicillin G-sulfathiazole of 14.5% for point source isolates versus 15.4 and 1.7%, respectively, for nonpoint source isolates. MAR profile homology, based on coefficient similarity, showed that isolates from point sources were markedly more diverse than isolates from nonpoint sources. Seven clusters were observed among point source isolates, with a coefficient value of approximately 1.8. In contrast, only four clusters were observed among nonpoint source isolates. Covariance matrices of data displayed six very distinct foci representing nonpoint source E. coli isolates. Importantly, E. coli isolates obtained directly from human and animal feces also clustered among point and nonpoint sources, respectively. We conclude that E. coli MAR profiles were associated with point and nonpoint sources of pollution within Apalachicola Bay and that this method may be useful in facilitating management of other estuaries. PMID:9212410

Parveen, S; Murphree, R L; Edmiston, L; Kaspar, C W; Portier, K M; Tamplin, M L

1997-07-01

393

In Vitro Efficacies and Resistance Profiles of Rifampin-Based Combination Regimens for Biofilm-Embedded Methicillin-Resistant Staphylococcus aureus.  

PubMed

To compare the in vitro antibacterial efficacies and resistance profiles of rifampin-based combinations against methicillin-resistant Staphylococcus aureus (MRSA) in a biofilm model, the antibacterial activities of vancomycin, teicoplanin, daptomycin, minocycline, linezolid, fusidic acid, fosfomycin, and tigecycline alone or in combination with rifampin against biofilm-embedded MRSA were measured. The rifampin-resistant mutation frequencies were evaluated. Of the rifampin-based combinations, rifampin enhances the antibacterial activities of and even synergizes with fusidic acid, tigecycline, and, to a lesser extent, linezolid, fosfomycin, and minocycline against biofilm-embedded MRSA. Such combinations with weaker rifampin resistance induction activities may provide a therapeutic advantage in MRSA biofilm-related infections. PMID:23959320

Tang, Hung-Jen; Chen, Chi-Chung; Cheng, Kuo-Chen; Wu, Kuan-Ying; Lin, Yi-Chung; Zhang, Chun-Cheng; Weng, Tzu-Chieh; Yu, Wen-Liang; Chiu, Yu-Hsin; Toh, Han-Siong; Chiang, Shyh-Ren; Su, Bo An; Ko, Wen-Chien; Chuang, Yin-Ching

2013-08-19

394

Geometry and faults tectonic activity of the Okavango Rift Zone, Botswana: Evidence from magnetotelluric and electrical resistivity tomography imaging  

NASA Astrophysics Data System (ADS)

We used Magnetotelluric (MT) and Electrical Resistivity Tomography (ERT) to investigate the geometry and nature of faults activity of the Okavango Rift Zone (ORZ) in Botswana, an incipient rift at the southern tip of the Southwestern Branch of the East African Rift System. The ORZ forms a subtle topographic depression filled with Quaternary lacustrine and fluvio-deltaic sediments and is bounded by NE-trending normal faults that are more prominent in the southeastern portion of the rift basin. An MT model from a regional (˜140 km) NW-SE trending MT transect shows that much of the rift basin is underlain by a broad asymmetrical low resistivity anomaly that slopes gently (˜1°) from NW to SE reaching a depth of ˜300 m. This anomaly suggests that faults in the southeastern part of the rift form a NW-dipping border fault zone and that the lacustrine and fluvio-deltaic sediments contain brackish to saline water filling the broad half-graben structure. Furthermore, MT and ERT models from detailed (4-13 km long) MT transects and resistivity profiles show that one border fault (Thamalakane) and two within-basin faults (Lecha and Tsau) in the southeastern part of the ORZ are characterized by a localized high conductivity anomaly while another border fault (Kunyere) lacks such an anomaly. These localized anomalies are attributed to channelized fresh surface water and saline groundwater percolating through these faults forming "fault zone conductors" and suggest actively displacing faults. The lack of a "fault zone conductor" in the Kunyere fault is interpreted as indicating diminishing displacement on this fault, and that strain was transferred to the Thamalakane fault further to the east. The fluids provide lubricant for the ORZ faults, hence preventing infrequent large magnitude earthquakes, but favoring frequent micro-seismicity.

Bufford, Kelsey Mosley; Atekwana, Estella A.; Abdelsalam, Mohamed G.; Shemang, Elijah; Atekwana, Eliot A.; Mickus, Kevin; Moidaki, Moikwathai; Modisi, Motsoptse P.; Molwalefhe, Loago

2012-04-01

395

Studies of Plasma Resistivity Through Measurements of Parallel Current Density and Electric Field in the MST Reversed Field Pinch  

Microsoft Academic Search

A two dimensional, toroidal equilibrium reconstruction code has been developed for the reversed field pinch. The parallel current density profile has been measured by incorporating several diagnostics into the code. A finite difference technique applied to a time series of smoothly varying equilibria determines the parallel inductive electric field profile. In the case of a rapidly changing equilibrium, realized in

J. K. Anderson; T. M. Biewer; C. B. Forest; R. O'Connell; J. S. Sarff

2001-01-01

396

Improving the Erosion Resistance of Electrical Insulating Materials Using Nano Fillers  

NASA Astrophysics Data System (ADS)

The paper presents the experimental results obtained to test the effect of nano-fillers on the aging performance of silicone rubber for outdoor applications and enamelled wire for motor insulation. The erosion resistance of silicone rubber (SIR) filled with 12 nm size fumed silica is compared to those filled with 5 ?m size silica filler using the ASTM 2303 Inclined Plane Tracking and Erosion Test. The erosion resistance of the SIR materials increased with increasing percentage of the fillers, and it was observed that 10% by weight of nano-filled SIR gives a performance that is similar to that obtained with 50% by weight of micro-filled SIR. The paper discusses the possible reasons for the improvement in the erosion resistance of nano-filled silicone composites using different material analysis techniques like Thermo Gravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). Also, the effect of using different nano fillers like alumina, fumed silica and titanium oxide on the erosion resistance of enamel wire insulating material subjected to different electrical stresses will be addresses. Surface roughness is used to evaluate the effect of different nano-fillers on the erosion resistance of enamel wire insulation.

El-Hag, A.; Ul-Haq, S.; Jayaram, S.; Cherney, E.

2007-08-01

397

Correlation between Group B Streptococcal Genotypes, Their Antimicrobial Resistance Profiles, and Virulence Genes among Pregnant Women in Lebanon  

PubMed Central

The antimicrobial susceptibility profiles of 76 Streptococcus agalactiae (Group B Streptococci [GBS]) isolates from vaginal specimens of pregnant women near term were correlated to their genotypes generated by Random Amplified Polymorphic DNA analysis and their virulence factors encoding genes cylE, lmb, scpB, rib, and bca by PCR. Based on the distribution of the susceptibility patterns, six profiles were generated. RAPD analysis detected 7 clusters of genotypes. The cylE gene was present in 99% of the isolates, the lmb in 96%, scpB in 94.7%, rib in 33%, and bca in 56.5% of isolates. The isolates demonstrated a significant correlation between antimicrobial resistance and genotype clusters denoting the distribution of particular clones with different antimicrobial resistance profiles, entailing the practice of caution in therapeutic options. All virulence factors encoding genes were detected in all seven genotypic clusters with rib and bca not coexisting in the same genome.

Hannoun, Antoine; Shehab, Marwa; Khairallah, Marie-Therese; Sabra, Ahmad; Abi-Rached, Roland; Bazi, Tony; Yunis, Khalid A.; Araj, George F.; Matar, Ghassan M.

2009-01-01

398

Application of data mining to customer profile analysis in the power electric industry  

Microsoft Academic Search

In Japan, the Revised Electric Utility Industry Law went into effect on March 21, 2000. The partial deregulation into the retail electric power supply sector means that electric power for extra-high voltage customers can now be supplied from companies other than the 10 major electric power companies (EPCos) and electricity rates charged to customers can be determined freely according to

Masashi Kitayama; R. Matsubara; Y. Izui

2002-01-01

399

Effect of high-pressures on the electrical resistivity of natural zeolites from Deccan Trap, Maharashtra, India  

Microsoft Academic Search

We report here the electrical resistivity measurements on two natural zeolites–natrolite and scolecite (from the Killari borehole, Maharashtra, India) as a function of pressure up to 8 GPa at room temperature. High-pressure electrical resistivity studies on hydrous alumino-silicate minerals are very helpful in understanding the role of water in deep crustal conductivities obtained from geophysical models. The results obtained by

G. Parthasarathy

2006-01-01

400

The effect of nucleus size on mechanical properties in electrical resistance spot welding of sheets used in automotive industry  

Microsoft Academic Search

In this study, the effects of welding current and time on the tensile-peel strength and tensile-shear strength of welding joint in electrical resistance spot welding of chromided micro-alloyed steel sheets having 0.8 mm thickness and galvanized chromided micro-alloyed steel sheets having 1.0 mm thickness were investigated. A timer and current controlled electrical resistance spot welding machine having 120 kVA capacity

S. Aslanlar

2006-01-01

401

Analytical model for the dynamic resistivity of electrically-exploded conductors  

SciTech Connect

A detailed model for the dynamic resistivity of an exploding conductor presents many difficulties. An electrically-exploded conductor undergoes significant hydrodynamic expansion as it is heated. Resistivity is a function of both the temperature and density of a conductor and realistic models for resistivity over the range of parameter space experienced by an exploding conductor are quite complex. See for example, the model of Lee and More (1984). Calculation of the hydrodynamic expansion of the conductor during and subsequent to the explosion is likewise dependent on detailed knowledge of the equation of state for the conductor in a range where few experimental data exist. A further complication is the strong magnetic field which couples the hydrodynamic expansion to the currents flowing in the expanding material. In spite of the difficulties, progress is being made on detailed modeling of fuses and exploding conductors (Lidemuth and co-workers, 1985). A simpler approach has proved to be quite useful for modeling the electrical behavior of exploding bridgewire and slapper detonators and for modeling the explosionss of large conductors exploded with large capacitor banks. In the work described here, a simple, empirical model was developed which can be expressed as a closed-form algebraic expression involving four parameters. This model has been used in a computer code which will calculate the burst times and burst currents for up to 15 conductors exploded in series in a capacitor-discharge circuit.

Lee, R.S.

1986-10-10

402

Monitoring Shallow Vadose Zone Moisture Dynamics using Electrical Resistivity Tomography and Electromagnetic Induction  

NASA Astrophysics Data System (ADS)

High-resolution electrical resistivity tomography (ERT) and electromagnetic induction (EMI) surveys are currently being used to monitor changes in shallow moisture conditions at five different locations within a clayey vineyard site located in Vineland, Ontario, Canada. These geophysical measurements have been collected every 2-3 weeks since late summer 2010. Our current data set consists of a 12 month period encompassing a wide range of seasonal soil conditions including dry summer, wet fall and spring, and frozen winter periods. At each monitoring location, an ERT survey is collected using a half meter electrode spacing with 48 electrodes. EMI surveys using EM-38 and EM-31 devices are concurrently collected in both vertical and horizontal dipole modes. In addition, gravimetric water content data has been collected at each location. Preliminary analysis of these data show significant temporal variation in both ERT and EMI response due to seasonal moisture changes in the shallow subsurface overlying relatively stable moisture conditions. Gravimetric water content data supports these geophysical observations. Through the inversion of ERT data, differences in the seasonal evolution of resistivity at various depths down to 3 metres can be extracted. Future analysis will focus on how these depth-varying conductivities can be quantitatively extracted from EM-38 and EM-31 data. Additionally, ongoing studies are looking into the use of ERT-acquired resistivity data to calibrate the apparent electrical conductivity values obtained from EM-38 surveys.

Endres, A. L.; Toy, C. W.; Steelman, C. M.

2011-12-01

403

Cell–Substrate Contact: Another Factor May Influence Transepithelial Electrical Resistance of Cell Layers Cultured on Permeable Filters  

Microsoft Academic Search

Transepithelial resistance (TER) measurement has often been used to study the paracellular transport properties of epithelia grown on permeable filters, especially the barrier function of tight junctions. However, the TER value includes another source, the resistance caused by cell–substrate contact, that may give rise to a high TER value if cell–substrate separation is small. In this study we use electric

Chun-Min Lo; Charles R. Keese; Ivar Giaever

1999-01-01

404

Modification of dependence of DC insulation resistivity of low density polyethylene (LDPE) on temperature and electric field using inorganic additives  

Microsoft Academic Search

One of the reasons which has hampered the use of polyethylene (PE) as an insulating material for HVDC cables is the inherent dependence of its dc insulation resistivity \\\\?sub\\\\?\\/sub on temperature T and electric field E. The objectives of the present work are: (i) to investigate the possibility of modifying the dependence of the insulation resistivity \\\\?sub\\\\?\\/sub of LDPE on

M. Salah Khalil; Joseph A. Jervase

2002-01-01

405

Influence of the use of rice husk ash on the electrical resistivity of concrete: A technical and economic feasibility study  

Microsoft Academic Search

This study investigated the behavior of apparent electrical resistivity of concrete mixes with the addition of rice husk ash using Wenner’s four electrode method. Tests included compressive strength, porosity and electrical conductivity of the pore solution. The contents of rice husk ash tested were 10%, 20% and 30% and results were compared with a reference mix with 100% Portland cement

A. L. G. Gastaldini; G. C. Isaia; T. F. Hoppe; F. Missau; A. P. Saciloto

2009-01-01

406

Electrical Resistivity Imaging and Quantification of Water Content Distribution during Infiltration and Redistribution in Soils  

NASA Astrophysics Data System (ADS)

Controlled by precipitation, evapotranspiration, recharge, and soil-hydraulic properties, water content is difficult to measure extensively in heterogeneous, natural environments without disturbing the subsurface. Time-lapse electrical resistivity imaging (ERI) is a cost-effective, minimally invasive method for imaging changes in water content in the vadose zone. Quantifying the relation between resistivity and water content, however, is challenging due to 1) spatially variable resolution, 2) spatial variability in the properties that relate resistivity to water content, 3) possible variability of soil-water salinity, and 4) the need for introduction of auxiliary information to achieve a unique solution of the inverse problem. Although quantitative integration of ERI data into hydrogeologic studies is complicated by these problems, the ERI technique provides copious and spatially exhaustive soft data that would otherwise be unavailable in this heterogeneous environment, especially over the multi-meter scale. We developed a methodology for analyzing ERI measurements in terms of water content, and applied it to ERI data collected during infiltration/redistribution experiments conducted in two soil types in the Mojave National Preserve. One experiment was conducted in an active wash, the other in a highly developed Pleistocene soil. In both, changes in water content through time were estimated from ERI to a depth of approximately 1.5 m during and after ponded infiltration in a 1-m diameter ring. Approximately 40 snapshots over approximately one week along intersecting two-dimensional lines were collected through time for both experiments. To reduce ambiguities in our interpretation, we use numerical simulations of water and electrical flow to convert estimated resistivity to water content, calibrating for variations in resolution, spatially variable petrophysical properties, and fluid salinity on the relation between water content and estimated resistivity. Additionally, we evaluate the application of local non-stationary rel