Sample records for electrical resistivity profiling

  1. Effective resist profile control

    NASA Astrophysics Data System (ADS)

    Liu, Chen-Yu; Wang, Chien-Wei; Huang, Chun-Ching; Chang, Ching-Yu; Ku, Yao-Ching

    2014-03-01

    To meet Moore's law, resist resolution improvement has become more and more important. However, it is difficult to improve resist resolution and keep vertical sidewall profile. For example, a high contrast hole resist may cause trench scum, due to very T-top profile. This paper reports several concepts for resist profile tuning without losing performance for lithographic factor , including mask error enhancement factor (MEEF), depth of focus (DOF), and critical dimension uniformity (CDU). To quantitative analysis the resist profile improvement, we define a new factor, Scum fail ratio (F/R%) for new techniques evaluation. The new techniques, including floatable additive, floatable PAG, and new monomer, are discussed. From X-SEM and CD-SEM data, former three concepts could improve resist sidewall profile quantitatively evaluated by Scum fail F/R% and keep lithographic factors. In addition, another key factor, resist residue defect, is also discussed. The high contrast resist with higher receding contact angle (RCA) easily generates more residue defect after development. With the new monomer composition, RCA of Resist E is decreased from 54 to 48 degree after development. Therefore, the residue defect is improved one order.

  2. Mapping Refuse Profile in Singapore Old Dumping Ground through Electrical Resistivity, S-Wave Velocity and Geotechnical Monitoring.

    PubMed

    Yin, Ke; Tong, Huan Huan; Noh, Omar; Wang, Jing-Yuan; Giannis, Apostolos

    2015-03-01

    The purpose of this study was to track the refuse profile in Lorong Halus Dumping Ground, the largest landfill in Singapore, by electrical resistivity and surface wave velocity after 25 years of closure. Data were analyzed using an orthogonal set of plots by spreading 24 lines in two perpendicular geophone-orientation directions. Both geophysical techniques determined that refuse boundary depth was 13 ± 2 m. The refuse boundary revealed a certain degree of variance, mainly ascribed to the different principle of measurements, as well as the high heterogeneity of the subsurface. Discrepancy was higher in spots with greater heterogeneity. 3D analysis was further conducted detecting refuse pockets, leachate mounding and gas channels. Geotechnical monitoring (borehole) confirmed geophysical outcomes tracing different layers such as soil capping, decomposed refuse materials and inorganic wastes. Combining the geophysical methods with borehole monitoring, a comprehensive layout of the dumping site was presented showing the hot spots of interests. PMID:25427774

  3. Electrical Resistance Experiment

    NSDL National Science Digital Library

    The Materials Science and Technology Teacher's Workshop (MAST) provides this experiment on electrical resistance and glass. The module involves breaking the glass from a light bulb and then measuring the resistance across the bulb's electrodes. The lesson includes a step by step explanation of the laboratory procedure and a link to a video clip.

  4. Electrical Resistivity Imaging

    EPA Science Inventory

    Electrical resistivity imaging (ERI) is a geophysical method originally developed within the mining industry where it has been used for decades to explore for and characterize subsurface mineral deposits. It is one of the oldest geophysical methods with the first documented usag...

  5. Electrical resistivity probes

    DOEpatents

    Lee, Ki Ha; Becker, Alex; Faybishenko, Boris A.; Solbau, Ray D.

    2003-10-21

    A miniaturized electrical resistivity (ER) probe based on a known current-voltage (I-V) electrode structure, the Wenner array, is designed for local (point) measurement. A pair of voltage measuring electrodes are positioned between a pair of current carrying electrodes. The electrodes are typically about 1 cm long, separated by 1 cm, so the probe is only about 1 inch long. The electrodes are mounted to a rigid tube with electrical wires in the tube and a sand bag may be placed around the electrodes to protect the electrodes. The probes can be positioned in a borehole or on the surface. The electrodes make contact with the surrounding medium. In a dual mode system, individual probes of a plurality of spaced probes can be used to measure local resistance, i.e. point measurements, but the system can select different probes to make interval measurements between probes and between boreholes.

  6. State Electricity Profiles

    EIA Publications

    2014-01-01

    The annual report contains data tables describing the electricity industry in each state. Data include generating capability, electricity generation, fuel use and prices, retail sales, emissions, and net interstate transfers of electricity.

  7. State Renewable Electricity Profiles

    EIA Publications

    2012-01-01

    Presents a summary of current and recent historical data for the renewable electric power industry. The data focuses on net summer capacity and net generation for each type of renewable generator, as well as fossil-fired and nuclear power plant types, for the period 2006 through 2010.

  8. Molecular Expressions: Electricity & Magnetism: Resistance

    NSDL National Science Digital Library

    Michael Davidson

    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..

  9. Electrically Variable Resistive Memory Devices

    NASA Technical Reports Server (NTRS)

    Liu, Shangqing; Wu, Nai-Juan; Ignatiev, Alex; Charlson, E. J.

    2010-01-01

    Nonvolatile electronic memory devices that store data in the form of electrical- resistance values, and memory circuits based on such devices, have been invented. These devices and circuits exploit an electrically-variable-resistance phenomenon that occurs in thin films of certain oxides that exhibit the colossal magnetoresistive (CMR) effect. It is worth emphasizing that, as stated in the immediately preceding article, these devices function at room temperature and do not depend on externally applied magnetic fields. A device of this type is basically a thin film resistor: it consists of a thin film of a CMR material located between, and in contact with, two electrical conductors. The application of a short-duration, low-voltage current pulse via the terminals changes the electrical resistance of the film. The amount of the change in resistance depends on the size of the pulse. The direction of change (increase or decrease of resistance) depends on the polarity of the pulse. Hence, a datum can be written (or a prior datum overwritten) in the memory device by applying a pulse of size and polarity tailored to set the resistance at a value that represents a specific numerical value. To read the datum, one applies a smaller pulse - one that is large enough to enable accurate measurement of resistance, but small enough so as not to change the resistance. In writing, the resistance can be set to any value within the dynamic range of the CMR film. Typically, the value would be one of several discrete resistance values that represent logic levels or digits. Because the number of levels can exceed 2, a memory device of this type is not limited to binary data. Like other memory devices, devices of this type can be incorporated into a memory integrated circuit by laying them out on a substrate in rows and columns, along with row and column conductors for electrically addressing them individually or collectively.

  10. State electricity profiles, March 1999

    SciTech Connect

    NONE

    1999-03-01

    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.

  11. Electrical resistivity of composite superconductors

    NASA Technical Reports Server (NTRS)

    Davis, J. H.; Lee, J. A.

    1983-01-01

    In addition to its superconducting properties, a superconductor is usually characterized by poor thermal conductivity and relatively high electrical resistivity in the normal state. To remedy this situation a study of superconducting properties of Cu-rich CU-Nb wires prepared by directionally solidified and cold-rolled technique was conducted. Some of the specimens were prepared by melting, directional solidification and diffusing in Tin. A total of 12 wire specimens was tested. Each specimen was analyzed by plotting experimental data into the following curves: the graph of the residual resistivity as a function of the specimen current at 4.3 K; and the graph of the electrical resistivity as a function of the temperature at a constant current.

  12. A GIS Method for Analyzing Electrical Resistivity

    NASA Astrophysics Data System (ADS)

    Hazzard, S. C.; Mutiti, S.; Berry, L. E.; GCSU Hydrogeologists

    2011-12-01

    Shallow electrical resistivity methods provide a relatively easy and cost-effective way of mapping the subsurface in wetland environments. Traditional ways of analyzing these data include curve matching, analytical methods, and pseudosections, which resemble geologic cross sections. Psuedosections and Three Dimensional (3D) results can be obtained from specialized software, such as RES3DINV or EarthImager. In recent years, ArcGIS has become very popular in environmental studies, but not as popular in electrical resistivity data analysis. In a previous study, we demonstrated that ArcGIS can be used in electrical resistivity analysis. The objective of this project was to assess the performance and accuracy of ArcGIS in analyzing 3D-wetland resistivity data. The study area used for this analysis was located at the Oconee River Greenway, in Milledgeville, Georgia. The area of focus was Alice Basin, which is one of the small basins in the Greenway wetland area. Within the wetland, we observed significant subsurface flow that transported water between basins and from the wetland into nearby Fishing Creek. This subsurface flow is typically restricted to a high permeability layer, and is responsible for most of the water loss within the wetland. To better understand how this wetland functions, electrical resistivity profiling was used to map the subsurface and the extent of the high permeability layer. The data were collected with an ULTRA MiniRes resistivity meter, using the dipole-dipole electrode configuration. We then developed an easy GIS-method for analyzing these data in 3D, and compared the results with those from the specialized resistivity software, RES3DINV. The top layer outputs for both programs were compared to visual observations and soils in the field. The spline interpolation technique in ArcGIS produced a superior match to the observed data, than results from RES3DINV. However, results for the lower layers were similar between the two programs. An additional advantage of the GIS results was that the layers can be assembled in ascending order, and then viewed in a 3D block in ArcScene viewer. The 3D block can also be saved into a video that displays different angles of view. Overall, ArcGIS can be used as a valuable, reliable, and readily available program for visualizing 3D resistivity data.

  13. The electrical resistance of vacuum

    NASA Astrophysics Data System (ADS)

    Bringuier, E.

    2013-07-01

    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.

  14. Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach

    PubMed Central

    Pan, Luan; Adamchuk, Viacheslav I.; Prasher, Shiv; Gebbers, Robin; Taylor, Richard S.; Dabas, Michel

    2014-01-01

    Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep) soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument. PMID:25057135

  15. Vertical soil profiling using a galvanic contact resistivity scanning approach.

    PubMed

    Pan, Luan; Adamchuk, Viacheslav I; Prasher, Shiv; Gebbers, Robin; Taylor, Richard S; Dabas, Michel

    2014-01-01

    Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep) soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument. PMID:25057135

  16. Electrical resistivity mechanism in magnetorheological elastomer

    E-print Network

    Paris-Sud XI, Université de

    Electrical resistivity mechanism in magnetorheological elastomer N Kchit, G Bossis L.P.M.C. UMR. Magnetorheological elastomers (MRE) are smart materials made by aligning magnetic microparticles inside a liquid

  17. 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. ...

  18. Continuous resistivity profiling data from the Corsica River Estuary, Maryland

    USGS Publications Warehouse

    Cross, V.A.; Bratton, J.F.; Worley, C.R.; Crusius, J.; Kroeger, K.D.

    2011-01-01

    Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine its importance in nutrient delivery to the Chesapeake Bay. The Corsica River Estuary represents a coastal lowland setting typical of much of the eastern bay. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the lower estuary in April and May 2007. Resource managers are concerned about nutrients that are entering the estuary via SGD that may be contributing to eutrophication, harmful algal blooms, and fish kills. Techniques employed in the study included continuous resistivity profiling (CRP), piezometer sampling of submarine groundwater, and collection of a time series of radon tracer activity in surface water. A CRP system measures electrical resistivity of saturated subestuarine sediments to distinguish those bearing fresh water (high resistivity) from those with saline or brackish pore water (low resistivity). This report describes the collection and processing of CRP data and summarizes the results. Based on a grid of 67.6 kilometers of CRP data, low-salinity (high-resistivity) groundwater extended approximately 50-400 meters offshore from estuary shorelines at depths of 5 to >12 meters below the sediment surface, likely beneath a confining unit. A band of low-resistivity sediment detected along the axis of the estuary indicated the presence of a filled paleochannel containing brackish groundwater. The meandering paleochannel likely incised through the confining unit during periods of lower sea level, allowing the low-salinity groundwater plumes originating from land to mix with brackish subestuarine groundwater along the channel margins and to discharge. A better understanding of the spatial variability and geological controls of submarine groundwater flow beneath the Corsica River Estuary could lead to improved models and mitigation strategies for nutrient over-enrichment in the estuary and in other similar settings.

  19. On equivalent resistance of electrical circuits

    NASA Astrophysics Data System (ADS)

    Kagan, Mikhail

    2015-01-01

    While the standard (introductory physics) way of computing the equivalent resistance of nontrivial electrical circuits is based on Kirchhoff's rules, there is a mathematically and conceptually simpler approach, called the method of nodal potentials, whose basic variables are the values of the electric potential at the circuit's nodes. In this paper, we review the method of nodal potentials and illustrate it using the Wheatstone bridge as an example. We then derive a closed-form expression for the equivalent resistance of a generic circuit, which we apply to a few sample circuits. The result unveils a curious interplay between electrical circuits, matrix algebra, and graph theory and its applications to computer science. The paper is written at a level accessible by undergraduate students who are familiar with matrix arithmetic. Additional proofs and technical details are provided in appendices.

  20. Antimicrobial resistance changes in enteric Escherichia coli of horses during hospitalisation: resistance profiling of isolates.

    PubMed

    Williams, A; Christley, R M; McKane, S A; Roberts, V L H; Clegg, P D; Williams, N J

    2013-01-01

    The aim of this study was to determine whether hospitalisation of horses leads to increased antimicrobial resistance in equine faecal Escherichia coli isolates. E. coli were cultured from faecal samples of horses on admission and after 7 days of hospitalisation; antimicrobial susceptibility was determined for eight antimicrobial agents. Resistance profiles of E. coli isolates were grouped into clusters, which were analysed to determine resistance patterns. Resistance to 7/8 antimicrobial agents and multi-drug resistance (MDR; resistance to ?3 antimicrobial classes) were significantly higher after 7 days of hospitalisation. Forty-eight resistance profiles were identified; 15/48 were present on day 0 only, 16/48 on day 7 only and 17/48 at both times of sampling. There was a significant association between day 7 profiles and resistance detected to an increased number of antimicrobial agents. Hospitalisation of horses for 7 days resulted in alterations in equine faecal E. coli antimicrobial resistance profiles. PMID:22967926

  1. Electrical resistance of a capillary endothelium

    PubMed Central

    1981-01-01

    The electrical resistance of consecutive segments of capillaries has been determined by a method in which the microvessels were treated as a leaky, infinite cable. A two-dimensional analytical model to describe the potential field in response to intracapillary current injection was formulated. The model allowed determination of the electrical resistance from four sets of data: the capillary radius, the capillary length constant, the length constant in the mesentery perpendicular to the capillary, and the relative potential drop across the capillary wall. Of particular importance were the mesothelial membranes covering the mesenteric capillaries with resistances several times higher than that of the capillary endothelium. 27 frog mesenteric capillaries were characterized. The average resistance of the endothelium was 1.85 omega cm2, which compares well with earlier determinations of the ionic permeability of such capillaries. However, heterogeneity with respect to resistance was observed, that of 10 arterial capillaries being 3.0 omega cm2 as compared with 0.95 omega cm2 for 17 mid- and venous capillaries. The average in situ length constant was 99 micrometers for the arterial capillaries and 57 micrometers for the mid- and venous capillaries. It is likely that the ions that carry the current must move paracellularly, through junctions that are leaky to small solutes. PMID:7241087

  2. Corrosion resistance of electrical steel after calorizing

    SciTech Connect

    Babich, S.T.; Zyabrev, A.A.; Skibina, G.V.; Kiselev, V.D.

    1992-03-01

    Magnetically soft 20895 electrical steel is used in instrument manufacture for production of relays. According to GOST 11036-75 the magnetic properties of the steel in the annealed condition are H{sub c} = 95.0 A/m and B{sub s} = 1.32 T with an external magnetic field strength of 500 A/m. During service the magnetic properties of the steel are preserved while the life of the part depends upon the corrosion resistance of the steel used in a humid industrial atmosphere. The surface of the steel is calorized to increase the corrosion resistance. 1 ref., 1 fig., 1 tab.

  3. An introduction to electrical resistivity in geophysics

    NASA Astrophysics Data System (ADS)

    Herman, Rhett

    2001-09-01

    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.

  4. Electrical resistance tomography from measurements inside a steel cased borehole

    DOEpatents

    Daily, William D. (Livermore, CA); Schenkel, Clifford (Walnut Creek, CA); Ramirez, Abelardo L. (Pleasanton, CA)

    2000-01-01

    Electrical resistance tomography (ERT) produced from measurements taken inside a steel cased borehole. A tomographic inversion of electrical resistance measurements made within a steel casing was then made for the purpose of imaging the electrical resistivity distribution in the formation remotely from the borehole. The ERT method involves combining electrical resistance measurements made inside a steel casing of a borehole to determine the electrical resistivity in the formation adjacent to the borehole; and the inversion of electrical resistance measurements made from a borehole not cased with an electrically conducting casing to determine the electrical resistivity distribution remotely from a borehole. It has been demonstrated that by using these combined techniques, highly accurate current injection and voltage measurements, made at appropriate points within the casing, can be tomographically inverted to yield useful information outside the borehole casing.

  5. Complex Electrical Resistivity for Monitoring DNAPL Contamination

    SciTech Connect

    Stephen R. Brown; David Lesmes; John Fourkas

    2003-09-12

    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.

  6. The Extracellular Electrical Resistivity in Cell Adhesion

    PubMed Central

    Gleixner, Raimund; Fromherz, Peter

    2006-01-01

    The interaction of cells in a tissue depends on the nature of the extracellular matrix. The electrical properties of the narrow extracellular space are unknown. Here we consider cell adhesion mediated by extracellular matrix protein on a solid substrate as a model system. We culture human embryonic kidney (HEK293) cells on silica coated with fibronectin and determine the electrical resistivity in the cell-solid junction \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\rho}_{{\\mathrm{J}}}=r_{{\\mathrm{J}}}d_{{\\mathrm{J}}}\\end{equation*}\\end{document} by combining measurements of the sheet resistance \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}r_{{\\mathrm{J}}}\\end{equation*}\\end{document} and of the distance \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}d_{{\\mathrm{J}}}\\end{equation*}\\end{document} between membrane and substrate. The sheet resistance is obtained from phase fluorometry of the voltage-sensitive dye ANNINE-5 by alternating-current stimulation from the substrate. The distance is measured by fluorescence interference contrast microscopy. We change the resistivity of the bath in a range from \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}66\\hspace{.167em}{\\Omega}\\hspace{.167em}{\\mathrm{cm}}\\end{equation*}\\end{document} to \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}750\\hspace{.167em}{\\Omega}\\hspace{.167em}{\\mathrm{cm}}\\end{equation*}\\end{document} and find that the sheet resistance \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}r_{{\\mathrm{J}}}\\end{equation*}\\end{document} is proportionally enhanced, but that the distance is invariant around \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}d_{{\\mathrm{J}}}=75\\hspace{.167em}{\\mathrm{nm}}\\end{equation*}\\end{document}. In all cases, the resulting resistivity \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\rho}_{{\\mathrm{J}}}\\end{equation*}\\end{document} is indistinguishable from the resistivity of the bath. A similar result is obtained for rat neurons cultured on polylysine. On that basis, we propose a “bulk resistivity in cell adhesion” model for cell-solid junctions. The observations suggest that the electrical interaction between cells in a tissue is determined by an extracellular space with the electrical properties of bulk electrolyte. PMID:16399830

  7. Electrical Resistance Tomography imaging of concrete

    SciTech Connect

    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

    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.

  8. Determination of Electrical Resistivity of Dry Coke Beds

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

    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 yet fully understood, this investigation is focused on the resistivity of dry coke beds consisting of different carbonaceous materials, i.e., coke beds containing no slag or metal. A method that reliably compares the electrical bulk resistivity of different metallurgical cokes at 1500 °C to 1600 °C is developed. The apparatus is dimensioned for industrial sized materials, and the electrical resistivity of anthracite, charcoal, petroleum coke, and metallurgical coke has been measured. The resistivity at high temperatures of the Magnitogorsk coke, which has the highest resistivity of the metallurgical cokes investigated, is twice the resistivity of the Corus coke, which has the lowest electrical resistivity. Zdzieszowice and SSAB coke sort in between with decreasing resistivities in the respective order. The electrical resistivity of anthracite, charcoal, and petroleum coke is generally higher than the resistivity of the metallurgical cokes, ranging from about two to about eight times the resistivity of the Corus coke at 1450 °C. The general trend is that the bulk resistivity of carbon materials decreases with increasing temperature and increasing particle size.

  9. Determination of electrical resistivity of dry coke beds

    SciTech Connect

    Eidem, P.A.; Tangstad, M.; Bakken, J.A. [NTNU, Trondheim (Norway)

    2008-02-15

    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 yet fully understood, this investigation is focused on the resistivity of dry coke beds consisting of different carbonaceous materials, i.e., coke beds containing no slag or metal. A method that reliably compares the electrical bulk resistivity of different metallurgical cokes at 1500{sup o} C to 1600{sup o}C is developed. The apparatus is dimensioned for industrial sized materials, and the electrical resistivity of anthracite, charcoal, petroleum coke, and metallurgical coke has been measured. The resistivity at high temperatures of the Magnitogorsk coke, which has the highest resistivity of the metallurgical cokes investigated, is twice the resistivity of the Corus coke, which has the lowest electrical resistivity. Zdzieszowice and SSAB coke sort in between with decreasing resistivities in the respective order. The electrical resistivity of anthracite, charcoal, and petroleum coke is generally higher than the resistivity of the metallurgical cokes, ranging from about two to about eight times the resistivity of the Corus coke at 1450{sup o}C. The general trend is that the bulk resistivity of carbon materials decreases with increasing temperature and increasing particle size.

  10. Electrical resistance of superconducting cable splices

    SciTech Connect

    Kuchnir, M.

    1997-07-01

    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.

  11. The electrical resistivity method in cased boreholes

    SciTech Connect

    Schenkel, C.J.

    1991-05-01

    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.

  12. Foliage Temperature Profile Responses to Stomatal Resistance and Foliage Density Profiles

    NASA Astrophysics Data System (ADS)

    Crago, R. D.; Qualls, R. J.; Zhao, W.

    2009-05-01

    Remotely sensed land surface temperatures provide valuable information regarding land surface processes such as the surface energy and water balances. However, it is now known that foliage and soil temperatures and even foliage skin temperatures at different levels within the same canopy, can vary by several K. This work was undertaken to improve our understanding of the processes that lead to vertical foliage temperature gradients. A multilayer canopy model was developed using a combination equation for each canopy layer and localized near-field (LNF) turbulent transport. The model was driven by data collected from a micrometeorological station at a dense grassland site in the Southern Great Plains, 1997, field experiment. The model was run with three vertical foliage density profiles and two stomatal resistance profiles for a total of six scenarios. Model results suggest that foliage temperature profiles are strongly affected by the canopy density and stomatal resistance profiles. The density profile determines the layers of canopy that absorb the most radiation for a given solar elevation angle. Dense portions of the canopy that receive a large fraction of net radiation tend to be warm. The enhanced transport efficiency near the canopy top tends to cool the upper layers, but this effect seems to be secondary to the radiation effect, since nearly all runs with uniform canopy density showed peak temperatures at the canopy top. In this study, the magnitude of the foliage temperature changed when the stomatal resistance profile was changed, but the basic shape of the foliage temperature profiles changed little with the stomatal resistance profile. The bulk behavior of the canopy, including production of sensible and latent heat fluxes and radiometric surface temperatures, was moderately affected by the canopy density and stomatal resistance profiles tested.

  13. A model for generating household electricity load profiles

    Microsoft Academic Search

    Jukka V. Paateron; Peter D. Lund

    2006-01-01

    SUMMARY Electricity consumption data profiles that include details on the consumption can be generated with a bottom-up load models. In these models the load is constructed from elementary load components that can be households or even their individual appliances. In this work a simplified bottom-up model is presented. The model can be used to generate realistic domestic electricity consumption data

  14. Electrical Resistivity Imaging to Quantify Spatial Soil Heterogeneit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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. T...

  15. Damage detection in carbon fiber composites using electrical resistance measurements

    NASA Astrophysics Data System (ADS)

    Gory, Ryan

    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.

  16. Repeatable change in electrical resistance of Si surface by mechanical and electrical nanoprocessing

    PubMed Central

    2014-01-01

    The properties of mechanically and electrically processed silicon surfaces were evaluated by atomic force microscopy (AFM). Silicon specimens were processed using an electrically conductive diamond tip with and without vibration. After the electrical processing, protuberances were generated and the electric current through the silicon surface decreased because of local anodic oxidation. Grooves were formed by mechanical processing without vibration, and the electric current increased. In contrast, mechanical processing with vibration caused the surface to protuberate and the electrical resistance increased similar to that observed for electrical processing. With sequential processing, the local oxide layer formed by electrical processing can be removed by mechanical processing using the same tip without vibration. Although the electrical resistance is decreased by the mechanical processing without vibration, additional electrical processing on the mechanically processed area further increases the electrical resistance of the surface. PMID:25489276

  17. Resistance to Cognitive Interference as a Function of MMPI Profile

    ERIC Educational Resources Information Center

    Golden, Charles J.; Golden, Ellen E.

    1975-01-01

    This study tests the hypothesis that resistance to interference as measured by Stroop Color and Word Test is related to psychopathology. College student subjects were classified into three groups on the basis of their Minnesota Multiphasic Personality Inventory (MMPI) profile high points. Subjects' cognitive interference scores significantly…

  18. ELECTRICAL IMPEDANCE TOMOGRAPHY ON A RESISTIVE NETWORK WITH INTERNAL CURRENTS

    E-print Network

    Kim, Yong Jung

    ELECTRICAL IMPEDANCE TOMOGRAPHY ON A RESISTIVE NETWORK WITH INTERNAL CURRENTS YONG JUNG KIM AND MIN from internal currents and the boundary conductivity. An electrically conducting body is discretized. The conductivity of a body decides the interior electrical cur- rent if a boundary injection current is given

  19. Profiles of America's leading renewable electricity developers

    Microsoft Academic Search

    2009-01-01

    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

  20. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Oak Ridge, TN); Fleischhauer, Grier S. (Midlothian, VA); Hajaligol, Mohammad R. (Richmond, VA); Lilly, Jr., A. Clifton (Chesterfield, VA)

    1997-01-01

    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, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  1. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

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

    1997-04-15

    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, {<=}1% Cr and either {>=}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {>=}0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, {<=}1% oxygen, {<=}3% Cu, balance Fe. 64 figs.

  2. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Oak Ridge, TN); Fleischhauer, Grier S. (Midlothian, VA); Hajaligol, Mohammad R. (Richmond, VA); Lilly, Jr., A. Clifton (Chesterfield, VA)

    2001-01-01

    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, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  3. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Oak Ridge, TN); Fleischhauer, Grier S. (Midlothian, VA); Hajaligol, Mohammad R. (Richmond, VA); Lilly, Jr., A. Clifton (Chesterfield, VA)

    1999-01-01

    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, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  4. Metamitron-resistant Chenopodium album from sugar beet: cross-resistance profile.

    PubMed

    Mechant, E; Bulcke, R

    2006-01-01

    In recent years, in several of the Belgian sugar beet growing regions, farmers have been confronted with unsatisfactory control of fat hen (Chenopodium album L.). Greenhouse bioassays conducted on reference C. album populations and on "suspected" populations from sugar beet fields where poor fat hen control had been observed, revealed that all "suspected" populations were resistant to metamitron, a key herbicide in the modern low rate weed control programs in sugar beet. These metamitron-resistant biotypes were all cross-resistant to atrazine. Since cross-resistance, particularly negative cross-resistance or reversed resistance, is known to play a major role in resistance management, other herbicides used in sugar beet and/or in rotational crops were tested to determine the cross-resistance profile of metamitron-resistant biotypes. Greenhouse bioassays were conducted using herbicides from different chemical families representing different modes of action. Cross-resistance was found for metribuzin, lenacil and chloridazon, all HRAC Group C1 herbicides that inhibit photosynthesis at PS II. The metamitron-resistant C. album populations examined showed negative cross-resistance to S-metolachlor (HRAC Group K3: inhibition of cell division), prosuifocarb (Group N: lipid synthesis, not AC-Case, inhibition), aclonifen and clomazone (both Group F3: inhibition of carotenoid biosynthesis). PMID:17390814

  5. Electricity Diversity Profiles for Energy Simulation of Office Buildings

    E-print Network

    Claridge, D.E.; Abushakra, B.; Haberl, J.S.; Sreshthaputra, A.

    diversity profile for energy simulation is to represent the hourly distribution of the energy use. However, the degree to which the use of the peak measured consumption for a building multiplied by the diver­ sity profile represents typical daily... factors based on measured electric­ ity consumption data for use in energy simulations and peak cooling load calculations in office buildings. This research project derived multiple sets of diversity factors from measured data in 32 office buildings...

  6. State Waste Discharge Permit Application: Electric resistance tomography testing

    SciTech Connect

    Not Available

    1994-04-01

    This permit application documentation is for a State Waste Discharge Permit issued in accordance with requirements of Washington Administrative Code 173-216. The activity being permitted is a technology test using electrical resistance tomography. The electrical resistance tomography technology was developed at Lawrence Livermore National Laboratory and has been used at other waste sites to track underground contamination plumes. The electrical resistance tomography technology measures soil electrical resistance between two electrodes. If a fluid contaminated with electrolytes is introduced into the soil, the soil resistance is expected to drop. By using an array of measurement electrodes in several boreholes, the areal extent of contamination can be estimated. At the Hanford Site, the purpose of the testing is to determine if the electrical resistance tomography technology can be used in the vicinity of large underground metal tanks without the metal tank interfering with the test. It is anticipated that the electrical resistance tomography technology will provide a method for accurately detecting leaks from the bottom of underground tanks, such as the Hanford Site single-shell tanks.

  7. Propagation through electrically coupled cells. Effects of a resistive barrier.

    PubMed Central

    Joyner, R W; Veenstra, R; Rawling, D; Chorro, A

    1984-01-01

    Action potential propagation through cardiac tissue occurs in a spatially inhomogeneous three-dimensional electrical syncytium composed of discrete cells with regional variations in membrane properties and intercellular resistance. In comparison with axons, cardiac tissue presents some differences in the application of core conductor cable theory. We have used analytical and numerical techniques to contrast the propagation of action potentials along nerve axons and along cardiac strands, including an explicit inclusion of cellular anatomical factors (the surface-to-volume ratio), the strand radius, and the regional distribution of longitudinal resistance. A localized decrease in the number of gap junctions will produce a functional resistive barrier, which can lead to unidirectional block of propagation if the tissue on two sides of the barrier in either excitability or passive electrical load. However, in some circumstances, a resistive barrier separating regions of different electrical load can actually facilitate propagation into the region of larger electrical load. PMID:6733238

  8. Thermal conductivity and electrical resistivity of porous materials

    NASA Technical Reports Server (NTRS)

    Koh, J. C. Y.; Fortini, A.

    1972-01-01

    Process for determining thermal conductivity and electrical resistivity of porous materials is described. Characteristics of materials are identified and used in development of mathematical models. Limitations of method are examined.

  9. BOSUMTWI IMPACT CRATER: USE OF ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT)

    E-print Network

    Paris-Sud XI, Université de

    of the tektites and microtektites of the Ivory Coast strewn field. Electrical resistivity survey was carried out/bedrock surface and the faults combined with the location of the tektite strewn field indicate that the about 0

  10. Hygienic quality and antibiotic resistance profile of sliced butchery.

    PubMed

    Voidarou, C; Alexopoulos, A; Plessas, S; Stavropoulou, E; Fotou, K; Tzora, A; Skoufos, I; Bezirtzoglou, E

    2011-12-01

    In order to investigate the microbiological quality of different meat products on the Greek market, 200 samples were collected from the following preparations: boiled turkey (n=50), boiled pork ham (n=50), smoked turkey (n=50) and smoked pork ham (n=50). In all cold meat preparations Clostridium perfringens vegetative and spore forms, Staphylococcus aureus, Escherichia coli and other Clostridium sp lec(-), as well as Lactobacillus, Bacillus sp. and Salmonella sp. were recovered. For instance Bacillus cereus was present in 6% of the samples. L. monocytogenes, Campylobacter jejuni and Campylobacter coli were rarely present (1-4%) while Yersinia enterocolitica and Campylobacter lari were absent. Differences in the occurrence of S. aureus, Salmonella sp., E. coli and spore forms of C. perfringens in boiled and smoked samples, reflects either the differences in the processing of the foods or could be associated to the extensive handling by the personnel during the purchasing (storage, slicing, wrapping). Antibiotic resistance on specific antibiotics for each pathogen was also studied. A multiresistance antibiotic profile was effective for most bacterial strains, and pronounced resistance profiles were observed for the commonly used antibiotics as ampicillin, penicillin, cephalothin, streptomycin followed by ceftriaxone and gentamycin. Albeit this high observed resistance profile, the tested strains generally conserved their susceptibility to amikacin, aztreonam, chloramphenicol and tylosin conserved an almost absent resistance. Antibiotics commonly used for therapeutic purposes, as well as antibiotics added to feed stuff of animals for increasing animal flesh production should contribute to the extensive spreading of antibiotic resistance in food and the environment. Systematically monitoring of the microbiological quality of cold butchery preparations must be done, in order to preserve food quality, optimizing the processing and elaboration methods of the product and safeguard the public health. PMID:21722746

  11. Parallel electric resistivity in the TFTR tokamak

    SciTech Connect

    Zarnstorff, M.C.; McGuire, K.; Bell, M.G.; Grek, B.; Johnson, D.; McCune, D.; Park, H.; Ramsey, A.; Taylor, G.

    1990-05-01

    The average parallel resistivity and the location of the q = 1 surface are found to be consistent with the predictions of neoclassical transport theory and inconsistent with classical resistivity (uncorrected for toroidal effects) for ohmic plasmas in the TFTR tokamak, both in near-equilibrium and during ramping of the plasma current. These observations are incompatible with theories predicting anomalous parallel resistivity in concert with anomalous perpendicular transport. 41 refs., 9 figs., 1 tab.

  12. Influence of Electrical Resistivity and Machining Parameters on Electrical Discharge Machining Performance of Engineering Ceramics

    PubMed Central

    Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

    2014-01-01

    Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 ?·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 ?·cm is obviously different from that with the electrical resistivity lower than 687 ?·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al2O3 ceramic. PMID:25364912

  13. Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

    PubMed

    Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

    2014-01-01

    Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 ?·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 ?·cm is obviously different from that with the electrical resistivity lower than 687 ?·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al2O3 ceramic. PMID:25364912

  14. Electrical Resistivity Imaging to Quantify Spatial Soil Heterogeneity

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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.

  15. The stimulation of heavy oil reservoirs with electrical resistance heating

    E-print Network

    Baylor, Blake Allen

    1990-01-01

    THE STIMULATION OF HEAVY OIL RESERVOIRS WITH ELECTRICAL RESISTANCE HEATING A Thesis by BLAKE ALLEN BAYLOR Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1990 Major Subject: Petroleum Engineering THE STIMULATION OF HEAVY OIL RESERVOIRS WITH ELECTRICAL RESISTANCE HEATING A Thesis by BLAKE ALLEN BAYLOR Approved as to style and content by: R. A. Wattenbarge (Chair of Committ e L. . Pipe...

  16. Collisional theory of electrical resistivity in trapped electron regimes

    Microsoft Academic Search

    B. H. Hui; N. K. Winsor; B. Coppi

    1977-01-01

    The distribution function is determined numerically for electrons subject to magnetic trapping, electron-electron, and electron-ion collisions, and an electric field large enough to invalidate the Spitzer–Ha¨rm (classical) approximation. The electrical resistivity is determined. It is compared with analytical theory for tokamaks, in the limit of large inverse aspect ratio &egr;, and small drift velocity Vd\\/Vth. The resistivity is plotted for

  17. Electrical resistance tomography using steel cased boreholes as electrodes

    DOEpatents

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

    1999-06-22

    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.

  18. Electrical resistance tomography using steel cased boreholes as electrodes

    DOEpatents

    Daily, William D. (Livermore, CA); Ramirez, Abelardo L. (Pleasanton, CA)

    1999-01-01

    An electrical resistance tomography method using 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 constain the models.

  19. ASSESSMENT OF ELECTRICAL RESISTIVITY METHOD TO MAP GROUNDWATER SEEPAGE ZONES

    E-print Network

    Toran, Laura

    ASSESSMENT OF ELECTRICAL RESISTIVITY METHOD TO MAP GROUNDWATER SEEPAGE ZONES IN HETEROGENEOUS for mapping groundwater seepage beneath lakes. We found that resistivity could predict out-seepage. A line) showed the water table dipping away from the lake, the steep gradient indicative of high out

  20. Collisional theory of electrical resistivity in trapped electron regimes

    Microsoft Academic Search

    B. H. Hui; N. K. Winsor; B. Coppi

    1976-01-01

    The distribution function is determined numerically for electrons subject to magnetic trapping, electron-electron and electron-ion collisions, and an electric field large enough to invalidate the Spitzer-Harm (classical) approximation. The electrical resistivity is determined and compared with analytical theory for Tokamaks.

  1. Young men's condom use resistance tactics: a latent profile analysis.

    PubMed

    Davis, Kelly Cue; Stappenbeck, Cynthia A; Norris, Jeanette; George, William H; Jacques-Tiura, Angela J; Schraufnagel, Trevor J; Kajumulo, Kelly F

    2014-01-01

    Research suggests that many men have used a variety of tactics to avoid using condoms when having sex with women. Guided by previous work demonstrating that men's use of coercive condom resistance tactics was predicted by negative attitudes toward women, inconsistent condom use, multiple partners, and sexual sensation seeking, the current study used latent profile analysis (LPA) to determine whether similar constructs were associated with a variety of resistance tactics. A community sample of 313 moderate-drinking men participated, of whom 80% reported employing at least one condom use resistance tactic since adolescence. The LPA revealed three classes of men. In general, men with the least negative beliefs about women, low levels of sexual sensation seeking and impulsivity, and positive beliefs about condoms (Condom Positive/Low Hostility) reported less use of resistance tactics than men with moderate sexual sensation seeking and impulsivity, negative beliefs about condoms, and moderate (Condom Negative/Moderate Hostility) or high (Condom Negative/High Hostility) negative attitudes about women. The classes also differed in terms of their sexual behaviors. This study demonstrated that sexual risk behavior interventions should not only address the tactics through which men resist using condoms but also tailor these efforts to men's individual characteristics. PMID:23548069

  2. Electrolyte injection with electrical resistance heating

    E-print Network

    Jaimes Gomez, Olmedo

    1992-01-01

    enough to produce a significant change in the pressure profile near the wellbore and, consequently, an increase in the oil produccion rate. THE ELECTROLYTE INJECTION MODEL One way to reduce the problem of water vaporization in the hot spots...

  3. 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...

  4. Theory of the residual electrical resistivity of binary actinide alloys

    NASA Astrophysics Data System (ADS)

    Tsiovkin, Yu. Yu.; Dremov, V. V.; Koneva, E. S.; Povzner, A. A.; Filanovich, A. N.; Petrova, A. N.

    2010-01-01

    A system of self-consistent equations has been proposed for the coherent potential approximation of the multiband conductivity model for the case of conduction electron scattering from chaotic electric fields of ions of disordered binary alloy components at zero temperature. It has been qualitatively demonstrated that the deviation of the concentration dependence of the residual electrical resistivity of actinide alloys with multiband conductivity from the Nordheim rule is caused by the explicit dependence of the electrical resistivity of the alloy on the magnitude and sign of the real part of the Green’s function at the Fermi level. The derived system of equations for the multiband coherent potential approximation has been used to calculate the concentration dependence of the density of states and the residual electrical resistivity of the alloys of neptunium and plutonium. The results of the calculations have been compared with the available experimental data.

  5. Study of solid–liquid mixing in agitated tanks through electrical resistance tomography

    Microsoft Academic Search

    Seyed Hosseini; Dineshkumar Patel; Farhad Ein-Mozaffari; Mehrab Mehrvar

    2010-01-01

    Electrical resistance tomography (ERT), which is a non-intrusive flow visualization technique, was used to investigate the solid–liquid mixing in an agitated tank equipped with a top-entering axial-flow impeller. The signals obtained from eight ERT planes were utilized to reconstruct the tomograms by using the linear back projection algorithm. The ERT measurements were correlated to solid concentration profiles by which the

  6. Influence of resistive internal kink on runaway current profile

    NASA Astrophysics Data System (ADS)

    Cai, Huishan; Fu, Guoyong

    2015-02-01

    An extended magnetohydrodynamic model including the effect of runaway current is developed and implemented in the M3D code. Based on this model, a simulation has been carried out to investigate the linear stability and the nonlinear evolution of the n = 1 resistive kink mode in the presence of runaway current. It is found that sawteeth oscillation is suppressed in a runaway plasma. The nonlinear evolution of the n = 1 mode only leads to a single sawtooth crash before reaching a new steady state axi-symmetric equilibrium with flattened current profile in the plasma core and q(0)>1.

  7. Delineating the Groundwater Recharge Zone in the Pingtung Plan , Taiwan with Electrical Resistivity Surveys

    NASA Astrophysics Data System (ADS)

    Wu, C.; Chang, P.; Chang, L.; Chen, J.; Huang, C.

    2012-12-01

    In this study we used the two-dimensional electrical resistivity imaging (ERI) method, as well as the core records of monitoring wells to help determine the groundwater recharge zone in Pingtung plain in southwestern Taiwan. Pingtung fluvial plain is one of the major groundwater resources in Taiwan which is composed of several alluvial fans deriving from the uplifted mountain area to the east and north of the plain. The thick gravel layer constitutes the main recharge area of the upper alluvial fans and the conductive clay sediments dominate most of the lower fans. With the core records, we found that, the gravel layers have higher resistivity (mostly over 200 Ohm-m) and the resistivities of the clayey layers are low (about 1~10 Ohm-m). Therefore with the resistivity surveys we can have more confidences for determining the boundary of the groundwater recharge area in the area in-between the monitoring wells. In the past two years, we have finished 24 two-dimensional electrical resistivity imaging profile lines from Meinong to Fangliao, the lines are oriented in the east-west direction, and each line was about 400 meters long. With the inverted results, we are able to characterize two major alluvial systems and their recharge zones in the Pingtung fluvial plain. The resistivities we measured almost are consistent to the core records of monitoring wells except for the Wanluan site, which shows thick gravel layer in the drilling records but has low resistivity in the nearby resistivity survey. A reasonable explanation is that the electrical resistivity is sensitive to clayey materials with lower resistivities. The intercalated clay within the gravel layers is not shown in the churn drilling records.

  8. Electrically tailored resistance switching in silicon oxide.

    PubMed

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

    2012-11-16

    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

  9. Electrical resistivity structure of the Great Slave Lake shear zone, northwest Canada: implications for tectonic history

    NASA Astrophysics Data System (ADS)

    Yin, Yaotian; Unsworth, Martyn; Liddell, Mitch; Pana, Dinu; Craven, James A.

    2014-10-01

    Three magnetotelluric (MT) profiles in northwestern Canada cross the central and western segments of Great Slave Lake shear zone (GSLsz), a continental scale strike-slip structure active during the Slave-Rae collision in the Proterozoic. Dimensionality analysis indicates that (i) the resistivity structure is approximately 2-D with a geoelectric strike direction close to the dominant geological strike of N45°E and that (ii) electrical anisotropy may be present in the crust beneath the two southernmost profiles. Isotropic and anisotropic 2-D inversion and isotropic 3-D inversions show different resistivity structures on different segments of the shear zone. The GSLsz is imaged as a high resistivity zone (>5000 ? m) that is at least 20 km wide and extends to a depth of at least 50 km on the northern profile. On the southern two profiles, the resistive zone is confined to the upper crust and pierces an east-dipping crustal conductor. Inversions show that this dipping conductor may be anisotropic, likely caused by conductive materials filling a network of fractures with a preferred spatial orientation. These conductive regions would have been disrupted by strike-slip, ductile deformation on the GSLsz that formed granulite to greenschist facies mylonite belts. The pre-dominantly granulite facies mylonites are resistive and explain why the GSLsz appears as a resistive structure piercing the east-dipping anisotropic layer. The absence of a dipping anisotropic/conductive layer on the northern MT profile, located on the central segment of the GSLsz, is consistent with the lack of subduction at this location as predicted by geological and tectonic models.

  10. Using electrical resistance tomography to map subsurface temperatures

    DOEpatents

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

    1994-09-13

    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. 1 fig.

  11. Using electrical resistance tomography to map subsurface temperatures

    DOEpatents

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

    1994-01-01

    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.

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

    PubMed Central

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

    2013-01-01

    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. PMID:23325171

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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.

  14. Resistance after firing protected electric match. [Patent application

    DOEpatents

    Montoya, A.P.

    1980-03-20

    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.

  15. High electrical resistivity carbon/graphite fibers

    NASA Technical Reports Server (NTRS)

    Vogel, F. L.; Forsman, W. C.

    1980-01-01

    Carbon/graphite fibers were chemically oxidized in the liquid phase to fibers of graphite oxide. Resistivity increases as high as 10,000 times were obtained, the oxidized fiber decomposed on exposure to atmosphere. A factor of 1,000 remained as a stable increment. The largest change observed was 1,000,000 times. Best results were obtained on the most highly graphitized fibers. Electrochemical oxidation yielded a lower increase--about 10 times, but provided a controllable method of synthesis and insight to the mechanism of reaction. Tensile tests indicated that the strength of the fiber on oxidation was decreased by no more than 25 percent.

  16. Evaluation of physico-mechanical properties of clayey soils using electrical resistivity imaging technique

    NASA Astrophysics Data System (ADS)

    Kibria, Golam

    Resistivity imaging (RI) is a promising approach to obtaining continuous profile of soil subsurface. This method offers simple technique to identify moisture variation and heterogeneity of the investigated area. However, at present, only qualitative information of subsurface can be obtained using RI. A study on the quantification of geotechnical properties has become important for rigorous use of this method in the evaluation of geohazard potential and construction quality control of landfill liner system. Several studies have been performed to describe electrical resistivity of soil as a function of pore fluid conductivity and surface conductance. However, characterization tests on pore water and surface charge are not typically performed in a conventional geotechnical investigation. The overall objective of this study is to develop correlations between geotechnical parameters and electrical resistivity of soil, which would provide a mean to estimate geotechnical properties from RI. As a part of the study, multiple regression analyses were conducted to develop practically applicable models correlating resistivity with influential geotechnical parameters. The soil samples considered in this study were classified as highly plastic clay (CH) and low plasticity clay (CL) according to Unified Soil Classification System (USCS). Based on the physical tests, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) analysis, kaolinite was identified as the dominant mineral with some traces of magnesium, calcium, potassium, and iron. Electrical resistivity tests were conducted on compacted clays and undisturbed samples under varied geotechnical conditions. The experimental results indicated that the degree of saturation substantially influenced electrical resistivity. Electrical resistivity decreased as much as 11 times from initial value for the increase of degree of saturation from 23 to 100% in the laboratory tests on compacted clays. In case of undisturbed soil samples, resistivity decreased as much as sixteen fold (49.4 to 3.2 Ohm-m) for an increase of saturation from 31 to 100%. Furthermore, the resistivity results were different for the specimens at a specific degree of saturation because of varied surface activity and isomorphous substitution of clayey soils. In addition to physical properties, compressibility of clays was correlated with electrical conductivity. Based on the investigation, it was determined that the electrical conductivity vs. pressure curves followed similar trends as e vs. logp curves. Multiple linear regression (MLR) models were developed for compacted and undisturbed samples using statistical analysis software SAS (2009). During model development, degree of saturation and CEC were selected as independent variables. The proposed models were validated using experimental results on a different set of samples. Moreover, the applicability of the models in the determination of degrees of saturation was evaluated using field RI tests.

  17. Analysis of the Drug Resistance Profile of Multidrug Resistance Protein 7 (ABCC10): Resistance to Docetaxel

    Microsoft Academic Search

    Elizabeth Hopper-Borge; Zhe-Sheng Chen; Irina Shchaveleva; Martin G. Belinsky; Gary D. Kruh

    2004-01-01

    The multidrug resistance protein (MRP) family consists of nine mem- bers that can be categorized according to whether or not a third (NH2- terminal) membrane-spanning domain is present. Three (MRP1, MRP2, and MRP3) of the four members that have this structural feature are able to confer resistance to natural product anticancer agents. We previously established that MRP7, the remaining family

  18. Effect of moisture, chloride and sulphate contamination on the electrical resistivity of Portland cement concrete

    Microsoft Academic Search

    M. Saleem; M. Shameem; S. E. Hussain; M. Maslehuddin

    1996-01-01

    When reinforcement corrosion is under resistive control, the chloride-contamination level is known to influence the electrical resistivity of concrete and hence the kinetics of reinforcement corrosion. However, other anions, such as SO4??, could also reduce the electrical resistivity of concrete. While some data exist on the relationship between moisture content on electrical resistivity of concrete, very little research has been

  19. Investigating electrical contact resistance losses in lithium-ion battery assemblies for hybrid and electric vehicles

    Microsoft Academic Search

    Peyman Taheri; Scott Hsieh; Majid Bahrami

    2011-01-01

    Lithium-ion (Li-ion) batteries are favored in hybrid-electric vehicles and electric vehicles for their outstanding power characteristics. In this paper the energy loss due to electrical contact resistance (ECR) at the interface of electrodes and current-collector bars in Li-ion battery assemblies is investigated for the first time. ECR is a direct result of contact surface imperfections, i.e., roughness and out-of-flatness, and

  20. Image-guided inversion of electrical resistivity data

    NASA Astrophysics Data System (ADS)

    Zhou, J.; Revil, A.; Karaoulis, M.; Hale, D.; Doetsch, J.; Cuttler, S.

    2014-04-01

    Electrical resistivity tomography (ERT) is based on solving a Poisson equation for the electrical potential and is characterized by a good sensitivity only in the vicinity of the electrodes used to gather the data. To provide more information to ERT, we propose an image-guided or structure-constrained inversion of the apparent resistivity data. This approach uses structural information obtained directly from a guiding image. This guiding image can be drawn from a high resolution geophysical method based on the propagation equation (e.g. migrated seismic or ground penetrating radar images) or possibly from a geological cross-section of the subsurface based on some prior geological expertise. The locations and orientations of the structural features can be extracted by image processing methods to determine the structure tensor and the semblances of the guiding image at a set of pixel. Then, we introduce these structural constraints into the inversion of the apparent resistivity data by weighting the four-direction smoothing matrix to smooth along, but not across, structural features. This approach allows preserving both discontinuities and coherences in the inversion of the resistivity data. The image-guided inversion is also combined with an image-guided interpolation approach used to focus a smooth resistivity image. This yields structurally-appealing resistivity tomograms, while the whole process remains computationally efficient. Such a procedure generates a more realistic resistivity distribution (closer to the true ones), which can be, in turn, used quantitatively using appropriate petrophysical transforms, to obtain parameters of interest such as porosity and saturation. We check the validity of this approach using two synthetic case studies as well as two real datasets. For the field data, the image used to guide the inversion of the electrical resistivity data is a GPR section in the first case and a combination of seismic and structural information in the second case, which corresponds to a geothermal site at Pagosa Springs, in Colorado.

  1. Electrical resistance sensors for soil water tension estimates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter, in a book to be published by the International Atomic Energy Agency/FAO Joint Division, provides detailed information on how to sense soil water tension with electrical resistance sensors. It provides insight into problems commonly encountered in using these sensors. Guidance on data r...

  2. Low Temperature Electrical Resistivity Measurements on Reactive Samples

    Microsoft Academic Search

    J. G. Pack; G. G. Libowitz

    1969-01-01

    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

  3. Complex electrical resistance tomography of a subsurface PCE plume

    Microsoft Academic Search

    A. Ramirez; W Daily; D. LeBrecque

    1996-01-01

    A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non-aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double

  4. Electrical resistivity imaging study of near-surface infiltration

    Microsoft Academic Search

    Angelos Lampousis

    2009-01-01

    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.

  5. Reservoir characterization combining elastic velocities and electrical resistivity measurements

    Microsoft Academic Search

    Carmen Teresa Gomez

    2009-01-01

    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

  6. Energy Saving Through High Frequency Electric Resistance Welding

    E-print Network

    Udall, H. N.

    1983-01-01

    High-Frequency electric resistance heating systems have been widely used for many years for both welding and heat treating. In the past the major reason for using High-Frequency heating processes has been because of their very much higher speeds...

  7. Electrical resistivity survey in soil science: a review

    Microsoft Academic Search

    A. Samouëlian; I. Cousin; A. Tabbagh; A. Bruand; G. Richard

    2005-01-01

    Electrical resistivity of the soil can be considered as a proxy for the spatial and temporal variability of many other soil physical properties (i.e. structure, water content, or fluid composition). Because the method is non-destructive and very sensitive, it offers a very attractive tool for describing the subsurface properties without digging. It has been already applied in various contexts like:

  8. Electrical Resistivity Changes in Saturated Rock under Stress.

    PubMed

    Brace, W F; Orange, A S

    1966-09-23

    Electrical resistivity of water-saturated crystalline rock such as granite, diabase, dunite, or quartzite changes by an order of magnitude prior to fracture of the rock in compression. The effect observed even under high confining pressure is due to formation of open cracks which first appear at one-third to two-thirds the fracture stress. PMID:17749731

  9. Health Monitoring of TPS Structures by Measuring Their Electrical Resistance

    NASA Astrophysics Data System (ADS)

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

    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.

  10. The Electrical Resistivity of FeSn Single Crystals

    Microsoft Academic Search

    Bengt Stenström

    1972-01-01

    The electrical resistivity of single crystal FeSn (hex B 35) has been measured for current parallel and perpendicular to the c-axis in the temperature range 4.2-420 K. The critical exponent is determined for I\\/\\/c at the antiferromagnetic ordering temperature TN = 364 K.

  11. Collisional theory of electrical resistivity in trapped electron regimes

    Microsoft Academic Search

    B. H. Hui; N. K. Winsor; B. Coppi

    1977-01-01

    The problem of the electrical resistivity of a magnetically confined toroidal plasma in the presence of magnetic trapping and in regimes where the magnitude of some relative perturbation is of the order of unity is examined using an extension of a computational model that has been adapted to study the behavior of trapped and untrapped electrons in Tokamaks. The Fokker-Planck

  12. Electrical resistivity of pure transuranium metals under pressure

    NASA Astrophysics Data System (ADS)

    Tsiovkin, Yu. Yu.; Lukoyanov, A. V.; Shorikov, A. O.; Tsiovkina, L. Yu.; Dyachenko, A. A.; Bystrushkin, V. B.; Korotin, M. A.; Anisimov, V. I.; Dremov, V. V.

    2011-06-01

    The influence of electronic structure evolution upon pressure on the temperature dependence of the electrical resistivity of pure Np, Pu, Am, and Cm metals has been investigated within the coherent potential approximation (CPA) for the many-bands conductivity model. The densities of states calculated within the local density approximation accounting for the Hubbard U and spin-orbit coupling (LDA+ U+SO method) for the cubic (bcc- or fcc-) structures with the volumes fitted to the relative volumes of real metal phases were used as a starting point for model investigations of the electrical resistivity. The obtained results were found in good agreement with a number of available experimental data. The origin of large magnitude of the resistivity of the actinides was discussed.

  13. Electrical resistance of complex two-dimensional structures of loops

    NASA Astrophysics Data System (ADS)

    Gomes, M. A. F.; Hora, R. R.; Brito, V. P.

    2011-06-01

    This work presents a study of the dc electrical resistance of a recently discovered hierarchical two-dimensional system which has a complex topology consisting of a distribution of disordered macroscopic loops with no characteristic size and a distribution of several types of contacts between loops. In addition to its intrinsic interest in the important context of low-dimensional systems and crumpled systems, the structures under study are of relevance in a number of areas including soft condensed matter and packing of DNA in viral capsids. In the particular case discussed here, the loops are made of layers of graphite with a height of tens of nanometers deposited on a substrate of cellulose. Experiments with these systems indicate an anomalous electrical resistance of sub-diffusive type. The results reported here are explained with scaling arguments and computer simulation. A comparison with the dc electrical properties of percolation clusters is made, and some other experimental issues as future prospects are commented.

  14. The deep lunar electrical conductivity profile - Structural and thermal inferences

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Herbert, F.; Sonett, C. P.

    1982-01-01

    Simultaneous lunar surface and orbital magnetometer records are reexamined, to ascertain intervals which may be suitable for measuring lunar inductive response in the solar wind and terrestrial magnetosheath. Power spectral estimates of the response tangent to the lunar surface, defined in terms of transfer and gain functions, are obtained for the 0.0001-0.01 Hz frequency range. The maximum consistency of estimates from different time intervals is found when the initial analysis is limited to the tangential direction of maximum incident power, or that direction in which the ratio of signal to background noise is greatest. Spherically symmetric plasma confinement theory is used in the interpretation of transfer function data, by way of forward model calculations, under the assumption of continuous electrical conductivity increase with depth. Results are presented for internal electrical conductivity profile, metallic core radius, and selenotherm limits.

  15. Influence of different illumination profiles on the on-state resistances of silicon carbide photoconductive semiconductor switches

    SciTech Connect

    Wang, Langning, E-mail: wanglangning@126.com; Xun, Tao; Yang, Hanwu; Liu, Jinliang; Zhang, Yu [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)] [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-04-15

    Characteristics of a silicon-carbide (SiC) photoconductive switch under different illumination profiles are presented. We triggered a V-doped semi-insulated 6H-SiC switch with lateral geometry using a laser beam of 532-nm wavelength. Photoconductivity tests for different spot profiles and locations show that such switches achieve a minimum on-state resistance when the switching gap is illuminated. The differences between on-state resistances are small for various partial illuminations of the switching gap. Semiconductor modeling is used to simulate the electric field and current profiles for different partial illuminations. The simulation results show poor on-state switch performance when partially illuminated. Based on these results, a more revealing circuit model for the switch matches well with experimental results for partial illuminations.

  16. Running title: electrical resistivity in forest soils1 Title: Monitoring forest soil properties with electrical resistivity3

    E-print Network

    Paris-Sud XI, Université de

    Cooperative Program Forests, Level II). We used electrical21 resistivity measurements to determine soil sampling locations and define sampling design.22 Soil cores were taken in the A horizon and analyzed for pH27 modest. Despite these levels of correlations, we were able to assess variations in soil28

  17. SEM viewing of gypsiferous material and study of their influence on electrical resistivity

    NASA Astrophysics Data System (ADS)

    Dafalla, M.; Fouzan, F. Al

    2012-04-01

    The gypsum rich material is often linked to the cavity formation due to the high solubility of cal-cium carbonate in the presence of acidic media. This work is dedicated to a close-up look to the structure of materials rich of gypsum and material of less or traces of sulfate ions. Electrical resistivity measurements were conducted along extended lines on sections involving cavities and the resulting profiles were examined for any changes. Forms and features of gypsum and minerals containing sulfates were studied and compared to sam-ples tested using SEM (scanning electron microscope). The chemical analyses (EDAX) using electron beam was carried out and the elements present within these samples were established. Quantitative chemical testing for some parameters including sulfate ions was carried out. Structural forms variation and changes are studied in view of the chemical composition. The electrical resistivity was measured using Syscal R1 electerical resis-tivity equipment for several spots near surface. Statistical correlations between sulfate ions content and elec-trical resistivity, for near surface soils, is presented. This study is aiming at utilizing the geophysical testing methods of sulfate rich soils and predicting future cavity formation in areas of high risk to cavities due to chemical weathering.

  18. Disentangling the physical contributions to the electrical resistance in magnetic domain walls: a multiscale study.

    PubMed

    Seemann, K M; Garcia-Sanchez, F; Kronast, F; Miguel, J; Kákay, A; Schneider, C M; Hertel, R; Freimuth, F; Mokrousov, Y; Blügel, S

    2012-02-17

    We analyze the origin of the electrical resistance arising in domain walls of perpendicularly magnetized materials by considering a superposition of anisotropic magnetoresistance and the resistance implied by the magnetization chirality. The domain wall profiles of L1(0)-FePd and L1(0)-FePt are determined by micromagnetic simulations based on which we perform first-principles calculations to quantify electron transport through the core and closure region of the walls. The wall resistance, being twice as high in L1(0)-FePd than in L1(0)-FePt, is found to be clearly dominated in both cases by a high gradient of magnetization rotation, which agrees well with experimental observations. PMID:22401245

  19. Electrical resistivity imaging of conductive plume dilution in fractured rock

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

    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.

  20. Micromechanical approach for electrical resistivity and conductivity of sandstone

    NASA Astrophysics Data System (ADS)

    Nguyen, S. T.

    2014-12-01

    The objective of this work is to employ the micromechanical approach for the modeling of the electrical resistivity and of the conductivity of sandstone. This type of rock is considered as a mixture of solid mineral and porous space filled fully or partially by conductive water. The Eshelby's solution of a spheroidal inclusion in a homogeneous matrix is employed. The differential effective medium model (DEM) with different concepts of the microstructure is developed for the calculation of the resistivity. The parametric study clarifies the impact of the microscopic parameters on the macroscopic electrical properties. The simulations are compared with the classical empirical and theoretical approaches as well as with the laboratory measurements. The results show a strong impact of the microstructure (the shape of the pore, the presence of non-conductive fluids in the pore space, the connectivity of conductive fluid) on the macroscopic resistivity and conductivity of sandstone. This approach gives a link between the microscopic physical parameters of the rock and the macroscopic electrical parameters such as the cementation exponent and the electrical formation factor.

  1. Electrical Resistance Technique to Monitor SiC Composite Detection

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Morscher, Gregory; Xia, Zhenhai

    2008-01-01

    Ceramic matrix composites are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems. The employment of these materials in such applications is limited by the ability to process components reliable and to accurately monitor and predict damage evolution that leads to failure under stressed-oxidation conditions. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. Electrical resistance of SiC/SiC composites is one technique that shows special promise towards this end. Since both the matrix and the fibers are conductive, changes in matrix or fiber properties should relate to changes in electrical conductivity along the length of a specimen or part. The effect of matrix cracking on electrical resistivity for several composite systems will be presented and some initial measurements performed at elevated temperatures under stress-rupture conditions. The implications towards electrical resistance as a technique applied to composite processing, damage detection (health monitoring), and life-modeling will be discussed.

  2. Mantle electrical conductivity profile of Niger delta region

    NASA Astrophysics Data System (ADS)

    Obiora, Daniel N.; Okeke, Francisca N.; Yumoto, K.; Agha, Stan O.

    2014-06-01

    The mantle electrical conductivity-depth profile of the Niger delta region in Nigeria has been determined using solar quiet day ionospheric current (Sq). The magnetometer data obtained in 2010 from geomagnetic stations installed in Lagos by magnetic dataset (MAGDAS) in 2008 and data from magnetometers installed in some parts of Niger delta by Center for Basic Space Science, University of Nigeria, Nsukka, were employed in this study. Gauss spherical harmonic analysis (SHA) method was used to separate the internal and external field contributions to Sq current system. The result depicted that the conductivity profile rose steadily from about 0.032 S/m at a depth of 89 km to 0.041 S/m at 100 km and 0.09 S/m at 221 km. This high conductivity region agreed with the global seismic low velocity region, the asthenosphere. The conductivity profile continued increasing downward until it got to 0.157 S/m at a depth of about 373 km (close to the base of upper mantle), 0.201 S/m at 784 km and reached 0.243 S/m at a depth of 1179 km at the lower mantle.

  3. A unique data acquisition system for electrical resistance tomography

    SciTech Connect

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

    1996-01-04

    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%.

  4. Electrical resistivity characterization of anisotropy in the Biscayne Aquifer.

    PubMed

    Yeboah-Forson, Albert; Whitman, Dean

    2014-01-01

    Electrical anisotropy occurs when electric current flow varies with azimuth. In porous media, this may correspond to anisotropy in the hydraulic conductivity resulting from sedimentary fabric, fractures, or dissolution. In this study, a 28-electrode resistivity imaging system was used to investigate electrical anisotropy at 13 sites in the Biscayne Aquifer of SE Florida using the rotated square array method. The measured coefficient of electrical anisotropy generally ranged from 1.01 to 1.12 with values as high as 1.36 found at one site. The observed electrical anisotropy was used to estimate hydraulic anisotropy (ratio of maximum to minimum hydraulic conductivity) which ranged from 1.18 to 2.83. The largest values generally were located on the Atlantic Coastal Ridge while the lowest values were in low elevation areas on the margin of the Everglades to the west. The higher values of anisotropy found on the ridge may be due to increased dissolution rates of the oolitic facies of the Miami formation limestone compared with the bryozoan facies to the west. The predominate trend of minimum resistivity and maximum hydraulic conductivity was E-W/SE-NW beneath the ridge and E-W/SW-NE farther west. The anisotropy directions are similar to the predevelopment groundwater flow direction as indicated in published studies. This suggests that the observed anisotropy is related to the paleo-groundwater flow in the Biscayne Aquifer. PMID:24033332

  5. Control of the electric-field profile in the Hall thruster A. Fruchtman

    E-print Network

    Control of the electric-field profile in the Hall thruster A. Fruchtman Holon Academic Institute; accepted 27 November 2000 Control of the electric-field profile in the Hall thruster through is reduced. Among electric propulsion devices Hall thrusters offer much higher thrust density than

  6. Electrical resistivity imaging of the near-surface structure of the Solfatara volcano

    NASA Astrophysics Data System (ADS)

    Giulia Di Giuseppe, Maria; Troiano, Antonio; Fedele, Alessandro; Patella, Domenico; Troise, Claudia; De Natale, Giuseppe

    2014-05-01

    We describe the results from an high-resolution study of the near-surface electrical resistivity structures carried out in the Solfatara area, located in the central part of the Campi Flegrei (CF) composite caldera, west of Naples, Italy. This area represents the most active zone within the CF area. It has been the site of an intense hydrothermal activity since Greek times, and currently exhibits the most impressive degassing manifestations. A direct relationship has always been observed between the increase of hydrothermal activity and ground uplift in the caldera. For this reason, dynamic of the Solfatara zone is considered a direct indicator of the volcanism taking place in the CF caldera. Since 2005 a new gradual increase of the hydrothermal activity and ground uplift has been observed. A steep growth of these effects has been recorded from 2012, accompanied by seismic events with hypocentres mostly concentrated below the area of Pozzuoli at depths ranging between 1 and 3 km, and highest magnitude of 1.8. It is thought that a further increase of the activity might lead to more critical conditions, including the occurrence of phreatic explosions. The detailed recovery of the structure and features of the shallow aquifers, mainly in the largest fumarole areas, is a crucial step for interpreting the ground movements and to improve our capability to forecast future pre-eruptive scenarios. Electrical resistivity results particularly sensitive to the presence of aqueous fluids and partial melts. By electrical imaging the volume of subsurface fluids can be constrained and the rheology of the subsoil can be reconstructed. To this aim, we have carried out eight profiles for electrical resistivity imaging, crossing the fumaroles field, deducting an electric model of the structural setting of the hydrothermal system in the first 100 m depth. Six of the profiles were 250 m long, with an electrodic distance of 5 m. Two longer profiles, up to 750 m, characterised by an electrodic distance of 10 m, was also realised, that crosses the whole Solfatara crater in the N-S and NE-WSW direction, respectively. The main electric features has been reconstructed and ERT results have been utilised to the aim of detailing the outlines of the fumarolic field defined by previous ground temperature, CO2 soil degassing, seismic noise, Bouguer anomaly mapping. A further analysis of the correlation between the recorded physical parameters and the main electric discontinuities has been realised.

  7. Thermal conductivity and electrical resistivity of porous material

    NASA Technical Reports Server (NTRS)

    Koh, J. C. Y.; Fortini, A.

    1971-01-01

    Thermal conductivity and electrical resistivity of porous materials, including 304L stainless steel Rigimesh, 304L stainless steel sintered spherical powders, and OFHC sintered spherical powders at different porosities and temperatures are reported and correlated. It was found that the thermal conductivity and electrical resistivity can be related to the solid material properties and the porosity of the porous matrix regardless of the matrix structure. It was also found that the Wiedermann-Franz-Lorenz relationship is valid for the porous materials under consideration. For high conductivity materials, the Lorenz constant and the lattice component of conductivity depend on the material and are independent of the porosity. For low conductivity, the lattice component depends on the porosity as well.

  8. Students' understanding of direct current resistive electrical circuits Paula Vetter Engelhardta)

    E-print Network

    Zollman, Dean

    Students' understanding of direct current resistive electrical circuits Paula Vetter Engelhardta regarding direct current resistive electric circuits often differ from the accepted explanations. At present resistive electrical circuits: current is consumed,4 and the battery is a source of constant current.5

  9. 3D electrical resistivity inversion using prior spatial shape constraints

    NASA Astrophysics Data System (ADS)

    Li, Shu-Cai; Nie, Li-Chao; Liu, Bin; Song, Jie; Liu, Zheng-Yu; Su, Mao-Xin; Xu, Lei

    2013-12-01

    To minimize the number of solutions in 3D resistivity inversion, an inherent problem in inversion, the amount of data considered have to be large and prior constraints need to be applied. Geological and geophysical data regarding the extent of a geological anomaly are important prior information. We propose the use of shape constraints in 3D electrical resistivity inversion. Three weighted orthogonal vectors (a normal and two tangent vectors) were used to control the resistivity differences at the boundaries of the anomaly. The spatial shape of the anomaly and the constraints on the boundaries of the anomaly are thus established. We incorporated the spatial shape constraints in the objective function of the 3D resistivity inversion and constructed the 3D resistivity inversion equation with spatial shape constraints. Subsequently, we used numerical modeling based on prior spatial shape data to constrain the direction vectors and weights of the 3D resistivity inversion. We established a reasonable range between the direction vectors and weights, and verified the feasibility and effectiveness of using spatial shape prior constraints in reducing excessive structures and the number of solutions. We applied the prior spatially shape-constrained inversion method to locate the aquifer at the Guangzhou subway. The spatial shape constraints were taken from ground penetrating radar data. The inversion results for the location and shape of the aquifer agree well with drilling data, and the number of inversion solutions is significantly reduced.

  10. Electrical resistivity studies of Cr - Ir alloy single crystals

    Microsoft Academic Search

    J. Martynova; H. L. Alberts; P. Smit

    1996-01-01

    Electrical resistivity has been measured for four Cr - Ir alloy single crystals for concentrations between 0.07 and 0.25 at.% Ir in the temperature range 4 to 1200 K. Well defined magnetic anomalies were observed at the Néel temperature 0953-8984\\/8\\/49\\/035\\/img1 of each alloy as well as at the incommensurate - commensurate (I - C) spin-density-wave (SDW) phase transition temperature of

  11. Electrical resistivity imaging of conductive plume dilution in fractured rock

    Microsoft Academic Search

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

    2007-01-01

    Electrical resistance tomography (ERT) was used to monitor a conductive plume dilution experiment that was conducted in fractured\\u000a basalt in order to assess its applications in this type of fractured-rock environment. Tap water was injected into an injection\\u000a well for 34 days to dilute a pre-existing potassium chloride (KCl) plume at a site in Idaho, USA. No further fluids were introduced

  12. Continuous resistivity profiling data from Great South Bay, Long Island, New York

    USGS Publications Warehouse

    Cross, V.A.; Bratton, J.F.; Kroeger, K.D.; Crusius, John; Worley, C.R.

    2013-01-01

    An investigation of submarine aquifers adjacent to the Fire Island National Seashore and Long Island, New York was conducted to assess the importance of submarine groundwater discharge as a potential nonpoint source of nitrogen delivery to Great South Bay. Over 200 kilometers of continuous resistivity profiling data were collected to image the fresh-saline groundwater interface in sediments beneath the bay. In addition, groundwater sampling was performed at sites (1) along the north shore of Great South Bay, particularly in Patchogue Bay, that were representative of the developed Long Island shoreline, and (2) at sites on and adjacent to Fire Island, a 50-kilometer-long barrier island on the south side of Great South Bay. Other field activities included sediment coring, stationary electrical resistivity profiling, and surveys of in situ pore water conductivity. Results of continuous resistivity profiling surveys are described in this report. The onshore and offshore shallow hydrostratigraphy of the Great South Bay shorelines, particularly the presence and nature of submarine confining units, appears to exert primary control on the dimensions and chemistry of the submarine groundwater flow and discharge zones. Sediment coring has shown that the confining units commonly consist of drowned and buried peat layers likely deposited in salt marshes. Low-salinity groundwater extends from 10 to 100 meters offshore along much of the north and south shores of Great South Bay based on continuous resistivity profiling data, especially off the mouths of tidal creeks and beneath shallow flats to the north of Fire Island adjacent to modern salt marshes. Human modifications of much of the shoreline and nearshore areas along the north shore of the bay, including filling of salt marshes, construction of bulkheads and piers, and dredging of navigation channels, has substantially altered the natural hydrogeology of the bay's shorelines by truncating confining units and increasing recharge near the shore in filled areas. Better understanding of the nature of submarine groundwater discharge along developed and undeveloped shorelines of embayments such as this could lead to improved models and mitigation strategies for nutrient overenrichment of estuaries.

  13. Complex electrical resistance tomography of a subsurface PCE plume

    SciTech Connect

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

    1996-01-01

    A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non-aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double walled tank where saturated layers of sand, bentonite and a sand/bentonite mixture were installed. Complex electrical resistance measurements were performed. Data were taken before the release, several times during, and then after the PCE was released. Magnitude and phase were measured at 1 and 64 Hz. Data from before the release were compared with those during the release for the purpose of imaging the changes in conductivity resulting from the plume. Conductivity difference tomographs showed a decrease in electrical conductivity as the DNAPL penetrated the soil. A pancake-shaped anomaly developed on the top of a bentonite layer at 2 m depth. The anomaly grew in magnitude and extent during the release and borehole television surveys data confirmed the anomaly to be free-product PCE whose downward migration was stopped by the low permeability clay. The tomographs clearly delineated the plume as a resistive anomaly.

  14. Dilatometric and electrical resistivity measurements in various phases of Nitinol

    NASA Astrophysics Data System (ADS)

    Uchil, Jayagopal; Mohanchandra, Kotekar P.; Mahesh, K. K.; Ganesh, Kumara K.

    1999-07-01

    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.

  15. Uncertainty analysis for common Seebeck and electrical resistivity measurement systems

    NASA Astrophysics Data System (ADS)

    Mackey, Jon; Dynys, Frederick; Sehirlioglu, Alp

    2014-08-01

    This work establishes the level of uncertainty for electrical measurements commonly made on thermoelectric samples. The analysis targets measurement systems based on the four probe method. Sources of uncertainty for both electrical resistivity and Seebeck coefficient were identified and evaluated. Included are reasonable estimates on the magnitude of each source, and cumulative propagation of error. Uncertainty for the Seebeck coefficient includes the cold-finger effect which has been quantified with thermal finite element analysis. The cold-finger effect, which is a result of parasitic heat transfer down the thermocouple probes, leads to an asymmetric over-estimation of the Seebeck coefficient. A silicon germanium thermoelectric sample has been characterized to provide an understanding of the total measurement uncertainty. The electrical resistivity was determined to contain uncertainty of ±7.0% across any measurement temperature. The Seebeck coefficient of the system is +1.0%/-13.1% at high temperature and ±1.0% near room temperature. The power factor has a combined uncertainty of +7.3%/-27.0% at high temperature and ±7.5% near room temperature. These ranges are calculated to be typical values for a general four probe Seebeck and resistivity measurement configuration.

  16. Characterization of subsurface stratigraphy along the lower American River floodplain using electrical resistivity, Sacramento, California, 2011

    USGS Publications Warehouse

    Burton, Bethany L.; Powers, Michael H.; Ball, Lyndsay B.

    2014-01-01

    In July 2011, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, completed a geophysical survey using electrical resistivity along an approximately 6-mile reach of the lower American River in Sacramento, California, to map near-surface lithological variations. This survey is a part of a manifold and comprehensive study of river-flow dynamics and geologic boundary-property knowledge necessary to estimate scour potential and levee erosion risk. Data were acquired on the left (south or west) bank between river mile 5 and 10.7 as well as a short section on the right bank from river mile 5.4 to 6. Thirteen direct-current resistivity profiles and approximately 8.3 miles of capacitively coupled resisistivity data were acquired along accessible areas of the floodplain between the levee and river bank. Capacitively coupled resistivity was used as a reconnaissance tool, because it allowed for greater spatial coverage of data but with lower resolution and depth of investigation than the DC resistivity method. The study area contains Pleistocene-age alluvial deposits, dominated by gravels, sands, silts, and clays, that vary in both lateral extent and depth. Several generations of lithologic logs were used to help interpret resistivity variations observed in the resistivity models.

  17. Detecting Damage in Ceramic Matrix Composites Using Electrical Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Craig E.; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90 deg fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  18. Detecting Cracks in Ceramic Matrix Composites by Electrical Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90o fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  19. Detecting cracks in ceramic matrix composites by electrical resistance

    NASA Astrophysics Data System (ADS)

    Smith, Craig; Gyekenyesi, Andrew

    2011-04-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90° fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen's electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  20. Electrical resistivity tomography investigations on a paleoseismological trenching study

    NASA Astrophysics Data System (ADS)

    Berge, Meriç Aziz

    2014-10-01

    Two-dimensional electrical resistivity tomography (ERT) investigation was performed in a paleoseismological trenching study. Data acquisition strategies such as the selection of electrode configuration and electrode intervals of ERT application were investigated in this paper. The ERT results showed that the Wenner and Wenner-Schlumberger arrays yielded similar results for subsurface characteristics whereas the DD array provided slightly different results. The combined usage of these arrays produced satisfactory images of the subsurface resistivity distribution. In addition, the electrode spacing tests revealed that a suitable interpretation of subsurface geology can be obtained from a 5 m electrode interval. However, a suitable trenching location defined by successful 2D resistivity models was obtained for 1 m electrode spacing. Therefore, the comparison of the trench and ERT results was also possible. The results of trenching and ERT studies substantially support each other.

  1. Rolling resistance of electric vehicle tires from track tests

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    Special low-rolling-resistance tires were made for DOE's ETV-1 electric vehicle. Tests were conducted on these tires and on a set of standard commercial automotive tires to determine the rolling resistance as a function of time during both constant-speed tires and SAE J227a driving cycle tests. The tests were conducted on a test track at ambient temperatures that ranged from 15 to 32 C (59 to 89 F) and with tire pressures of 207 to 276 kPa (30 to 40 psi). At a contained-air temperature of 38 C (100 F) and a pressure of 207 kPa (30 psi) the rolling resistances of the electric vehicle tires and the standard commercial tires, respectively, were 0.0102 and 0.0088 kilogram per kilogram of vehicle weight. At a contained-air temperature of 38 C (100 F) and a pressure of 276 kPa (40 psi) the rolling resistances were 0.009 and 0.0074 kilogram per kilogram of vehicle weight, respectively.

  2. Metallic nanowire networks: effects of thermal annealing on electrical resistance.

    PubMed

    Langley, D P; Lagrange, M; Giusti, G; Jiménez, C; Bréchet, Y; Nguyen, N D; Bellet, D

    2014-11-21

    Metallic nanowire networks have huge potential in devices requiring transparent electrodes. This article describes how the electrical resistance of metal nanowire networks evolve under thermal annealing. Understanding the behavior of such films is crucial for the optimization of transparent electrodes which find many applications. An in-depth investigation of silver nanowire networks under different annealing conditions provides a case study demonstrating that several mechanisms, namely local sintering and desorption of organic residues, are responsible for the reduction of the systems electrical resistance. Optimization of the annealing led to specimens with transmittance of 90% (at 550 nm) and sheet resistance of 9.5 ? sq(-1). Quantized steps in resistance were observed and a model is proposed which provides good agreement with the experimental results. In terms of thermal behavior, we demonstrate that there is a maximum thermal budget that these electrodes can tolerate due to spheroidization of the nanowires. This budget is determined by two main factors: the thermal loading and the wire diameter. This result enables the fabrication and optimization of transparent metal nanowire electrodes for solar cells, organic electronics and flexible displays. PMID:25267592

  3. Metallic nanowire networks: effects of thermal annealing on electrical resistance

    NASA Astrophysics Data System (ADS)

    Langley, D. P.; Lagrange, M.; Giusti, G.; Jiménez, C.; Bréchet, Y.; Nguyen, N. D.; Bellet, D.

    2014-10-01

    Metallic nanowire networks have huge potential in devices requiring transparent electrodes. This article describes how the electrical resistance of metal nanowire networks evolve under thermal annealing. Understanding the behavior of such films is crucial for the optimization of transparent electrodes which find many applications. An in-depth investigation of silver nanowire networks under different annealing conditions provides a case study demonstrating that several mechanisms, namely local sintering and desorption of organic residues, are responsible for the reduction of the systems electrical resistance. Optimization of the annealing led to specimens with transmittance of 90% (at 550 nm) and sheet resistance of 9.5 ? sq-1. Quantized steps in resistance were observed and a model is proposed which provides good agreement with the experimental results. In terms of thermal behavior, we demonstrate that there is a maximum thermal budget that these electrodes can tolerate due to spheroidization of the nanowires. This budget is determined by two main factors: the thermal loading and the wire diameter. This result enables the fabrication and optimization of transparent metal nanowire electrodes for solar cells, organic electronics and flexible displays.

  4. Temperature dependence of electrical resistivity in ?-plutonium alloys

    NASA Astrophysics Data System (ADS)

    Tsiovkin, Yu Yu; Tsiovkina, L. Yu

    2007-02-01

    The anomalous behaviour of the temperature dependence of the electrical resistivity in Pu-based dilute alloys (?-Pu) has been considered within the Mott two-band conductivity model. It has been shown that the physical origin of the negative sign of the temperature coefficient of resistivity (TCR), observed in ?-Pu based alloys, is the interference between electron-impurity and electron-phonon interactions. A simple criterion for negative TCR observability at high temperatures (T>?D) was found and applied to explain qualitatively the experimental data on the TCR in some Pu-based dilute alloys. To make a numerical evaluation of the electrical resistivity, the coherent potential approach to the Mott two-band conductivity model was combined with the ab initio obtained fcc-Pu density of states (as the starting point in the iteration procedure) and applied to the calculation of resistivity temperature dependence in pure Pu and Pu-5 at.% Al alloy. The results are compared with experimental data.

  5. Variations of electric field and electric resistivity of air caused by dust motion

    NASA Astrophysics Data System (ADS)

    Seran, E.; Godefroy, M.; Renno, N.; Elliott, H.

    2013-08-01

    report results of a field campaign conducted in the Nevada desert with a suite of electric field instruments consisting of a field mill (FM) and a short dipole antenna (SDA). Furthermore, we show that a combination of the measurements of these two instruments allows the estimation of the electric resistivity of air, an important quantity that is extremely difficult to measure near the Earth's surface. The electric resistivity of air is found to vary between 1.5 · 1013 and 6 · 1013 ? m and to correlate with changes in electric field. Vertical DC electric fields with amplitudes up to 6 kV m-1 were observed to correspond to clouds of dust blowing through the measurement site. Enhanced DC and AC electric fields are measured during periods when horizontal wind speed exceeds 7 m s-1, or around twice the background value. We suggest that low-frequency emissions, below ~200 Hz, are generated by the motion of electrically charged particles in the vicinity of the SDA electrode and propose a simple model to reproduce the observed spectra. According to this model, the spectral response is controlled by three parameters, (i) the speed of the charged particles, (ii) the charge concentration, and (iii) the minimum distance between the particle and the electrode. In order to explain the electric fields measured with the FM sensors at different heights, we developed a multilayer model that relates the electric field to the charge distribution. For example, a nonlinear variation of the electric field observed by the FM sensors below 50 cm is simulated by a near-surface layer of tens of centimeters that is filled with electrically charged particles that carry a predominantly negative charge in the vicinity of the soil. The charge concentration inside this layer is estimated to vary between 1012 and 5 · 1013 electrons m-3.

  6. Electrical resistivity tomography, VES and magnetic surveys for dam site characterization, Wukro, Northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Haile, Tigistu; Atsbaha, Solomun

    2014-09-01

    Geophysical surveys involving the techniques of electrical resistivity imaging, electrical sounding and magnetics were employed to characterize the ground conditions at a proposed dam site at Hizaeti-Afras, Wukro, North Ethiopia. The techniques were utilized to map the depth to the competent formations, their relative suitability for foundation work and the presence and extent of weak zones in the subsurface. The work has mapped the different lithologic units of the subsurface and determined the depth to the basement rocks in the area. Through correlation of the inverse model resistivity sections of the imaging surveys, the geoelectric section of the sounding survey and the magnetic profile plots with available borehole lithologic logs, it is shown that the results very well supplement the geotechnical point data in addition to providing a wider coverage in mapping areas of weak ground that could otherwise be missed with widely spaced borehole information. The combined results of the survey show the proposed dam axis to be unsuitable. The power of the electrical resistivity imaging technique and its potential to map the shallow subsurface with adequate resolution are illustrated. The result is a strong suggestion that geophysical techniques can be used to assist and extrapolate borehole geotechnical data especially when large area is to be used for development of large infrastructure.

  7. Electrical Resistivity in Non-stoichiometric MoO2

    NASA Astrophysics Data System (ADS)

    Alves, L. M. S.; Benaion, S. S.; Romanelli, C. M.; dos Santos, C. A. M.; da Luz, M. S.; de Lima, B. S.; Oliveira, F. S.; Machado, A. J. S.; Guedes, E. B.; Abbate, M.; Mossanek, R. J. O.

    2015-04-01

    MoO y with 1.85 ? y ? 2.20 has been studied by X-ray diffractometry and photoemission spectroscopy at room temperature and by electrical resistance as a function of temperature from 2 to 300 K. Although X-ray diffractograms are very similar to the stoichiometric MoO2 with monoclinic structure of the space group P21/c (14), the electrical properties are strongly dependent on the oxygen composition. Samples with y = 1.85 and 1.90 show anomalous behavior in electrical conductivity. Photoemission and X-ray absorption spectroscopy measurements suggest that this anomalous behavior is related to the presence of Mo3+ ions such as in KxMoO2 compound.

  8. Resistivity Profiling for Mapping Gravel Layers That May Control Contaminant Migration at the Amargosa Desert Research Site, Nevada

    USGS Publications Warehouse

    Lucius, Jeffrey E.; Abraham, Jared D.; Burton, Bethany L.

    2008-01-01

    Gaseous contaminants, including CFC 113, chloroform, and tritiated compounds, move preferentially in unsaturated subsurface gravel layers away from disposal trenches at a closed low-level radioactive waste-disposal facility in the Amargosa Desert about 17 kilometers south of Beatty, Nevada. Two distinct gravel layers are involved in contaminant transport: a thin, shallow layer between about 0.5 and 2.2 meters below the surface and a layer of variable thickness between about 15 and 30 meters below land surface. From 2003 to 2005, the U.S. Geological Survey used multielectrode DC and AC resistivity surveys to map these gravel layers. Previous core sampling indicates the fine-grained sediments generally have higher water content than the gravel layers or the sediments near the surface. The relatively higher electrical resistivity of the dry gravel layers, compared to that of the surrounding finer sediments, makes the gravel readily mappable using electrical resistivity profiling. The upper gravel layer is not easily distinguished from the very dry, fine-grained deposits at the surface. Two-dimensional resistivity models, however, clearly identify the resistive lower gravel layer, which is continuous near the facility except to the southeast. Multielectrode resistivity surveys provide a practical noninvasive method to image hydrogeologic features in the arid environment of the Amargosa Desert.

  9. Monitoring soil volume wetness in heterogeneous soils by electrical resistivity. A field-based pedotransfer function

    NASA Astrophysics Data System (ADS)

    Brillante, Luca; Bois, Benjamin; Mathieu, Olivier; Bichet, Vincent; Michot, Didier; Lévêque, Jean

    2014-08-01

    Modern irrigation techniques require accurate, rapid, cost-effective, spatial measurement of soil moisture. Electrical Resistivity Tomography (ERT) meets most of these requirements, but needs to be calibrated for each use because it is very sensitive to differences in soil characteristics. In this study, a pedotransfer function approach is used to remove the need for site-specific calibration, allowing ERT to be used directly to measure soil moisture. The study site was a hillslope vineyard, where eight calcaric-cambisol soil profiles were identified. From 2012 to 2013, 23 000 soil volume wetness measurements were acquired by Time Domain Reflectometry, and over 100 000 electrical resistivity data were collected in 160 ERT acquisitions. To better understand the ERT signal, soil texture, gravel content, cation exchange capacity, CaCO3, pH, organic carbon and total nitrogen were analysed in 64 soil samples from the study site. The sensitivity of ERT to differences in soil characteristics makes it difficult to establish a unique model linking electrical resistivity and soil moisture in heterogeneous soils. This study presents two possible solutions to overcome this problem, which are differentiated by the availability of data on soil characteristics. When these data are not available, it is possible to fit a number of different models for each homogeneous soil layer, but a site-specific calibration is necessary at least once. Conversely, when soil characteristics are available, they can be integrated into the model to build a pedotransfer function. A unique, accurate model is obtained in this way for all samples. In soils with similar characteristics to those observed, the function can be used directly to measure soil moisture by ERT. Developing pedotransfer functions such the one presented here could greatly improve, simplify and develop the use of electrical resistivity to measure soil moisture.

  10. Comparing the risk profiles of renewable and natural gas-fired electricity contracts

    Microsoft Academic Search

    Ryan Wiser; Devra Bachrach; Mark Bolinger; William Golove

    2004-01-01

    Electricity policymakers, industry participants, analysts, and even consumers have become acutely aware of the ever-present risks that face the delivery of electricity. Recent instability in the electricity industry illustrates the need for thoughtful resource planning to balance the cost, reliability, and risk of electricity supply. This article evaluates the relative risk profiles of renewable and natural gas generating plants. It

  11. Suitability of Archie's Law For Interpreting Electrical Resistivity Data

    NASA Astrophysics Data System (ADS)

    Singha, K.; Gorelick, S. M.

    2003-12-01

    Electrical resistivity tomography (ERT) is examined as a method to provide spatially continuous images of saline tracer concentrations during transport through unconsolidated fluid-saturated media. It is frequently accepted that there exists a quantitative relationship between the electrical conductivity of dilute electrolytes in pore water and bulk electrical conductivity of the subsurface measured using resistivity methods. The assumed relationship is typically Archie's Law. We tested the applicability of Archie's Law to field-scale data collected over a 10 m by 14 m area. A 20-day weak-dipole tracer test was conducted, in which 2 g/L NaCl were introduced into the upper 30 m of the saturated zone in a coarse sand and gravel aquifer. Cross-well ERT data were collected at 4 geophysical monitoring wells and inverted in 3-D. Fluid electrical conductivity was measured directly from a multilevel sampler. The change in the direct measurements of fluid electrical conductivity exceeded the change in bulk conductivity values in the tomograms by an order of magnitude. The estimated Archie formation factor from the field data was not constant with time, due largely to smoothing during the image reconstruction process. We illustrate by modeling synthetic cases over the field site that the ERT response is difficult to match to measured fluid conductivities due to the variability in the effects of regularization, which change in both space and time. Analysis of both the field data and synthetic cases suggest that Archie's Law cannot be used to directly scale ERT conductivities to fluid conductivities.

  12. Connection equation and shaly-sand correction for electrical resistivity

    USGS Publications Warehouse

    Lee, Myung W.

    2011-01-01

    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.

  13. Prediction of antibiotic resistance by gene expression profiles

    PubMed Central

    Suzuki, Shingo; Horinouchi, Takaaki; Furusawa, Chikara

    2014-01-01

    Although many mutations contributing to antibiotic resistance have been identified, the relationship between the mutations and the related phenotypic changes responsible for the resistance has yet to be fully elucidated. To better characterize phenotype–genotype mapping for drug resistance, here we analyse phenotypic and genotypic changes of antibiotic-resistant Escherichia coli strains obtained by laboratory evolution. We demonstrate that the resistances can be quantitatively predicted by the expression changes of a small number of genes. Several candidate mutations contributing to the resistances are identified, while phenotype–genotype mapping is suggested to be complex and includes various mutations that cause similar phenotypic changes. The integration of transcriptome and genome data enables us to extract essential phenotypic changes for drug resistances. PMID:25517437

  14. Local Resistance Profiling of Ultra-Shallow Junction with Spike Lamp and Laser Annealing Using Scanning Spreading Resistance Microscopy

    NASA Astrophysics Data System (ADS)

    Abo, Satoshi; Tanaka, Yuji; Nishikawa, Kazuhisa; Wakaya, Fujio; Iwamatsu, Toshiaki; Oda, Hidekazu; Takai, Mikio

    2008-11-01

    Local resistance profiles of ultra-shallow arsenic implanted into silicon with an energy of 3.5 keV and a dose of 1.2×1015 ions/cm2 activated by conventional spike lamp and laser annealing were measured by SSRM in a nitrogen atmosphere with a depth resolution of less than 10 nm for investigating the combination of the conventional spike lamp and laser annealing. Spike lamp annealing at 1050 °C followed by laser annealing at a power density of 0.42 kW/mm2 was found to give the lowest sheet resistance. The resistance profiles obtained by SSRM also indicated the lowest resistance for the sample after spike lamp annealing at 1050 °C followed by laser annealing with a power density of 0.42 kW/mm2. Laser annealing alone with a power density of 0.42 kW/mm2 resulted in the higher sheet resistance, though the shallower resistance profile could be obtained. Spike lamp annealing followed by laser annealing procedures are effective in activating shallow arsenic profiles.

  15. Complex electrical resistance tomography of a subsurface PCE plume

    SciTech Connect

    Ramirez, A.; Daily W. [Lawrence Livermore National Laboratory, CA (United States); LaBrecque, D. [Univ. of Arizona, Tucson, AZ (United States)

    1996-11-01

    A controlled experiment was conducted to evaluate the performance of complex electrical resistivity tomography (CERT) for detecting and delineating free product dense non aqueous phase liquid (DNAPL) in the subsurface. One hundred ninety liters of PCE were released at a rate of 2 liters per hour from a point 0.5 m below ground surface. The spill was conducted within a double walled tank where saturated layers of sand, bentonite and a sand/bentonite mixture were installed. Complex electrical resistance measurements were performed from 4 vertical electrode arrays, each with 10 electrodes spaced between 3 m and 0.5 m depth. Data were taken before the release, several times during, and then after the PCE was released. Magnitude and phase were measured at 1 and 64 Hz. Data from before the release were compared with those during the release for the purpose of imaging the changes in conductivity resulting from the plume. Conductivity difference tomographs showed a decrease in electrical conductivity as the DNAPL penetrated the soil. A pancake-shaped anomaly developed on the top of a bentonite layer at 2 m depth. The anomaly grew in magnitude and extent during the release and borehole television surveys data confirmed the anomaly to be free-product PCE whose downward migration was stopped by the low permeability clay. The tomographs clearly delineated the plume as a resistive anomaly. Images showing phase changes caused by the spill are also presented. The phase changes at 64 Hz suggest that the DNAPL spill increased the induced polarization (IP) effect of the clay layers.

  16. Using electrical resistance probes for moisture determination in switchgrass windrows

    SciTech Connect

    Chesser Jr., G. D.; Davis, J. D.; Purswell, J. L.; Lemus, R.

    2011-08-01

    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 needed to measure MC in switchgrass using electrical resistance meters, ii) to determine the effects of pressure and probe orientation on MC measurement and iii) to generate MC calibration equations for electrical resistance meters using switchgrass in the senescence growth stage. Two meters (Meter 1, Farmex HT-PRO; Meter 2, Delmhorst F-2000) were selected based on commercial availability. A forage compression apparatus was designed and constructed with on-farm materials and methods to provide a simple system of applying pressure achievable by any forage producer or researcher in the field. Two trials were performed to test four levels of moisture contents (10, 20, 30, and 40%), five pressures (0, 1.68, 3.11, 4.55, 6.22 kN/m 2; 0, 35, 65, 95, 130 lb/ft 2), and two probe orientations (axial and transverse) in a 4x5x2 factorial design. Results indicated that meter accuracy increased as pressure increased. Regression models accounted for 91% and 81% of the variation for Meter 1 and Meter 2 at a pressure of 4.55 kN/m 2 (95 lb/ft 2) and a transverse probe orientation. Calibration equations were developed for both meters to improve moisture measurement accuracy for farmers and researchers in the field.

  17. Lipid Profiles in Wheat Cultivars Resistant and Susceptible to Tan Spot and the Effect of Disease on the Profiles

    PubMed Central

    Kim, Dongwon; Jeannotte, Richard; Welti, Ruth; Bockus, William W.

    2013-01-01

    Lipid profiles in wheat leaves and the effects of tan spot on the profiles were quantified by mass spectrometry. Inoculation with Pyrenophora tritici-repentis significantly reduced the amount of leaf lipids, including the major plastidic lipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), which together accounted for 89% of the mass spectral signal of detected lipids in wheat leaves. Levels of these lipids in susceptible cultivars dropped much more quickly during infection than those in resistant cultivars. Furthermore, cultivars resistant or susceptible to tan spot displayed different lipid profiles; leaves of resistant cultivars had more MGDG and DGDG than susceptible ones, even in non-inoculated plants. Lipid compositional data from leaves of 20 non-inoculated winter wheat cultivars were regressed against an index of disease susceptibility and fitted with a linear model. This analysis demonstrated a significant relationship between resistance and levels of plastidic galactolipids and indicated that cultivars with high resistance to tan spot uniformly had more MGDG and DGDG than cultivars with high susceptibility. These findings suggest that lipid composition of wheat leaves may be a determining factor in the resistance response of cultivars to tan spot. PMID:23035632

  18. Optical device with low electrical and thermal resistance Bragg reflectors

    DOEpatents

    Lear, K.L.

    1996-10-22

    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.

  19. Evaluation of the radiation resistance of electrical insulation materials

    NASA Astrophysics Data System (ADS)

    Perrin, Sh.; Schönbacher, H.; Tavlet, M.; Widler, R.

    2002-12-01

    The qualification of insulating materials for electrical cables is often accomplished according to the IEC 60544 standard of the International Electrotechnical Commission. The mechanical properties of the polymeric insulators are tested prior and after irradiation at relatively high dose rates. To assess the ageing of selected materials under realistic service conditions, usually at lower dose rate, an IEC Working Group has proposed extrapolation methods (IEC 61244-2), one of which is applied here for a cable sheathing material from Huber+Suhner. The method is found to be suitable to compare radiation resistance data of different materials irradiated under different conditions.

  20. Optical device with low electrical and thermal resistance bragg reflectors

    DOEpatents

    Lear, Kevin L. (Albuquerque, NM)

    1996-01-01

    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.

  1. Rainfall infiltration process in mountain headwater region using electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Ono, M.; Yamamiya, K.; Shimada, J.

    2008-12-01

    Many researchers have studied about the hydrological process, especially rainfall-runoff process, in the headwater region using multi hydrometric methods. Since the possibility has been recognized that bedrock groundwater has important role to play in the rainfall-runoff process, it is important to comprehend the rainfall infiltration process within fluctuations of bedrock groundwater. However, we would need many hydrological instruments to understand this process precisely. So we have applied electrical resistivity tomography (ERT) method to understand rainfall infiltration process in the area that is estimated the contribution of bedrock groundwater for rainfall-runoff processes. Resistivity changes with the saturation rate of the pore fluid in the subsurface material. So it is possible to estimate spatial and temporal distribution of subsurface water by using ERT. In this study, we will estimate rainfall infiltration process in mountain headwater region using resistivity method. The study area is the Mamushi-dani watershed in Shiranui, Kumamoto, Japan. We described the bedrock groundwater storage systems using resistivity method in this watershed previously. Resistivity has been observed at 2 measurement lines in slope areas of this watershed. Both measurement lines have 47m in length, 1m electrode spacing and 48 electrodes. We used the multi-electrode system, NEXT-400(Kowa Co. Ltd., Japan) for measuring apparent resistivity and the application software, E-tomo (Diaconsultant Co. Ltd., Japan) for inversion of apparent resistivity data. The observed resistivity data were compared with water head observed at borehole and specific discharge observed at foot of the watershed. Inverted resistivity profiles and observed hydrological data showed the interface between saturated and unsaturated zone. During rainfall occurs, resistivity in surface area gets lower than that before the rainfall and resistivity in some part of unsaturated area shows increasing tendency. Both variations indicate the movement of subsurface water. Thus, we could estimate spatial and temporal distribution of subsurface water using resistivity data, and understand rainfall infiltration process precisely. Acknowledgements This study was financially supported by THE FUKADA GRANTS-IN-AIDS, Japan.

  2. Investigating Root Zone Soil Moisture Using Electrical Resistivity and Crop Modeling

    NASA Astrophysics Data System (ADS)

    Diker, K.; Van Dam, R. L.; Hyndman, D. W.; Kendall, A. D.; Bhardwaj, A. K.; Hamilton, S. K.; Basso, B.

    2011-12-01

    An accurate understanding of soil moisture variability is critical for agroecological modeling and for understanding the implications of climate change for agriculture. In recent years, electrical resistivity (ER) methods have successfully been used to characterize soil moisture in a range of environments, but there remains a need to better link these data to climate variability, soil textural properties, and vegetation and root dynamics. We present results for a novel ER measurement system at the Great Lakes Bioenergy Research Center (GLBRC) in southwest Michigan. Permanent multi-electrode arrays were installed beneath a range of annual and perennial biofuel crop types including corn, soybean, various grasses, and poplars. The ER arrays provide both high spatial resolution 2D and high temporal resolution 1D apparent resistivity data (4 week and 2 hour intervals, respectively). These data, along with a forward simulation of electrical resistivity in the soil column, are used to calibrate and refine root growth dynamics modules within the crop growth and soil hydrologic model SALUS (System Approach to Land Use Sustainability). Simulations are compared to 1D TDR-inferred soil moisture data. Variability in root zone dynamics among different biofuel cropping systems is explored. Total water use and efficiency, along with profile root water extraction, vary considerably among the crops.

  3. Reservoir characterization combining elastic velocities and electrical resistivity measurements

    NASA Astrophysics Data System (ADS)

    Gomez, Carmen Teresa

    2009-12-01

    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

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

    USGS Publications Warehouse

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

    2009-01-01

    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.

  5. K(+) channel profile and electrical properties of Arabidopsis root hairs.

    PubMed

    Ivashikina, N; Becker, D; Ache, P; Meyerhoff, O; Felle, H H; Hedrich, R

    2001-11-23

    Ion channels and solute transporters in the plasma membrane of root hairs are proposed to control nutrient uptake, osmoregulation and polar growth. Here we analyzed the molecular components of potassium transport in Arabidopsis root hairs by combining K(+)-selective electrodes, reverse transcription-PCR, and patch-clamp measurements. The two inward rectifiers AKT1 and ATKC1 as well as the outward rectifier GORK dominated the root hair K(+) channel pool. Root hairs of AKT1 and ATKC1 loss-of-function plants completely lack the K(+) uptake channel or exhibited altered properties, respectively. Upon oligochitin-elicitor treatment of root hairs, transient changes in K(+) fluxes and membrane polarization were recorded in wild-type plants, while akt1-1 root hairs showed a reduced amplitude and pronounced delay in the potassium re-uptake process. This indicates that AKT1 and ATKC1 represent essential alpha-subunits of the inward rectifier. Green fluorescent protein (GFP) fluorescence following ballistic bombardment with GORK promoter-GFP constructs as well as analysis of promoter-GUS lines identified this K(+) outward rectifier as a novel ion channel expressed in root hairs. Based on the expression profile and the electrical properties of the root hair plasma membrane we conclude that AKT1-, ATKC- and GORK-mediated potassium transport is essential for osmoregulation and repolarization of the membrane potential in response to elicitors. PMID:11728473

  6. Chronological change of electrical resistance in GeCu2Te3 amorphous film induced by surface oxidation

    NASA Astrophysics Data System (ADS)

    Saito, Yuta; Shindo, Satoshi; Sutou, Yuji; Koike, Junichi

    2014-11-01

    Unusual chronological electrical resistance change behavior was investigated for amorphous GeCu2Te3 phase change material. More than a 1 order decrease of electrical resistance was observed in the air even at room temperature. The resistance of the amorphous film gradually increased with increasing temperature and then showed a drop upon crystallization. Such unusual behavior was attributed to the oxidation of the amorphous GeCu2Te3 film. From the compositional depth profile measurement, the GeCu2Te3 film without any capping layer was oxidized in air at room temperature and the formed oxide was mainly composed of germanium oxide. Consequently, a highly-conductive Cu-rich layer was formed in the vicinity of the surface of the film, which reduced the total resistance of the film. The present results could provide insight into the chronological change of electrical resistance in amorphous chalcogenide materials, indicating that not only relaxation of the amorphous, but also a large atomic diffusion contributes to the chronological resistance change.

  7. Electrical resistivity tomography at the DOE Hanford site

    SciTech Connect

    Narbutovskih, S.M.

    1996-04-04

    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.

  8. Use of electrical resistivity tomography to evaluate processes in soils

    NASA Astrophysics Data System (ADS)

    Damasceno, Victor M.

    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.

  9. Antimicrobial Resistance Profiles of Campylobacter jejuni Isolates from Wild Birds in Sweden†

    PubMed Central

    Waldenström, Jonas; Mevius, Dik; Veldman, Kees; Broman, Tina; Hasselquist, Dennis; Olsen, Björn

    2005-01-01

    In order to determine the occurrence and frequency of resistant strains of the bacterium Campylobacter jejuni and to establish baseline MICs in isolates from an environmental reservoir, the resistance profiles of 10 antimicrobial substances were determined for 137 C. jejuni isolates from wild birds in Sweden. Observed MICs were generally low, with only low to moderate incidence of resistance to the tested compounds. One isolate, however, was resistant to nalidixic acid and ciprofloxacin, indicating that quinolone-resistant genotypes of C. jejuni have the potential to spread to wild bird hosts. PMID:15870331

  10. Genotype and antibiotic resistance profile of Escherichia coli strains involved in canine pyometra

    Microsoft Academic Search

    Reza Ghanbarpour; Baharak Akhtardanesh

    Eighty-four Escherichia coli isolates from canine pyometra were examined to detect the antibiotic resistance profiles, phylogroup\\/subgroups and virulence\\u000a genes. Twenty-seven (32.14%) antibiotic-resistant isolates were recovered, which were classified into 19 different antibiotic\\u000a resistance patterns. The maximum resistance was against sulfadiazine and tetracycline. The antibiotic resistant isolates mostly\\u000a belonged to A (40.74%) and D (29.62%) phylogroups. Among other examined isolates, 19.04%

  11. Monitoring Damage Accumulation in Ceramic Matrix Composites Using Electrical Resistivity

    NASA Technical Reports Server (NTRS)

    Smith, Craig E.; Morscher, Gregory N.; Xia, Zhenhai H.

    2008-01-01

    The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection and accurate life prediction for high-temperature ceramic matrix composites. Woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composites (CMC) possess unique properties such as high thermal conductivity, excellent creep resistance, improved toughness, and good environmental stability (oxidation resistance), making them particularly suitable for hot structure applications. In specific, CMCs could be applied to hot section components of gas turbines [1], aerojet engines [2], thermal protection systems [3], and hot control surfaces [4]. The benefits of implementing these materials include reduced cooling air requirements, lower weight, simpler component design, longer service life, and higher thrust [5]. It has been identified in NASA High Speed Research (HSR) program that the SiC/SiC CMC has the most promise for high temperature, high oxidation applications [6]. One of the critical issues in the successful application of CMCs is on-board or insitu assessment of the damage state and an accurate prediction of the remaining service life of a particular component. This is of great concern, since most CMC components envisioned for aerospace applications will be exposed to harsh environments and play a key role in the vehicle s safety. On-line health monitoring can enable prediction of remaining life; thus resulting in improved safety and reliability of structural components. Monitoring can also allow for appropriate corrections to be made in real time, therefore leading to the prevention of catastrophic failures. Most conventional nondestructive evaluation (NDE) techniques such as ultrasonic C-scan, x-ray, thermography, and eddy current are limited since they require structural components of complex geometry to be taken out of service for a substantial length of time for post-damage inspection and assessment. Furthermore, the typical NDE techniques are useful for identifying large interlaminar flaws, but insensitive to CMC materials flaws developed perpendicular to the surface under tensile creep conditions. There are techniques such as piezoelectric sensor [7,8], and optical fiber [9,10] that could be used for on-line health monitoring of CMC structures. However, these systems involve attaching an external sensor or putting special fibers in CMC composites, which would be problematic at high temperature applications.

  12. Electrical resistivity imaging study of near-surface infiltration

    NASA Astrophysics Data System (ADS)

    Lampousis, Angelos

    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).

  13. Probabilistic electrical resistivity tomography of a CO2 sequestration analog

    NASA Astrophysics Data System (ADS)

    Lochbühler, Tobias; Breen, Stephen J.; Detwiler, Russell L.; Vrugt, Jasper A.; Linde, Niklas

    2014-08-01

    Electrical resistivity tomography (ERT) is a well-established method for geophysical characterization and has shown potential for monitoring geologic CO2 sequestration, due to its sensitivity to electrical resistivity contrasts generated by liquid/gas saturation variability. In contrast to deterministic inversion approaches, probabilistic inversion provides the full posterior probability density function of the saturation field and accounts for the uncertainties inherent in the petrophysical parameters relating the resistivity to saturation. In this study, the data are from benchtop ERT experiments conducted during gas injection into a quasi-2D brine-saturated sand chamber with a packing that mimics a simple anticlinal geological reservoir. The saturation fields are estimated by Markov chain Monte Carlo inversion of the measured data and compared to independent saturation measurements from light transmission through the chamber. Different model parameterizations are evaluated in terms of the recovered saturation and petrophysical parameter values. The saturation field is parameterized (1) in Cartesian coordinates, (2) by means of its discrete cosine transform coefficients, and (3) by fixed saturation values in structural elements whose shape and location is assumed known or represented by an arbitrary Gaussian Bell structure. Results show that the estimated saturation fields are in overall agreement with saturations measured by light transmission, but differ strongly in terms of parameter estimates, parameter uncertainties and computational intensity. Discretization in the frequency domain (as in the discrete cosine transform parameterization) provides more accurate models at a lower computational cost compared to spatially discretized (Cartesian) models. A priori knowledge about the expected geologic structures allows for non-discretized model descriptions with markedly reduced degrees of freedom. Constraining the solutions to the known injected gas volume improved estimates of saturation and parameter values of the petrophysical relationship.

  14. Gene expression profiling discriminates cerebral malaria-susceptible mice and cerebral malaria-resistant mice

    E-print Network

    Paris-Sud XI, Université de

    Gene expression profiling discriminates cerebral malaria-susceptible mice and cerebral malaria-resistant mice Short title: Gene expression profiles in mouse malaria Nicolas F. Delahaye1 , Nicolas Coltel2;2 Abstract The development of mouse cerebral malaria (CM) upon Plasmodium berghei ANKA infection is under

  15. ERIC-PCR typing profiles of Enterobacter cloacae are stable after development of advanced cephalosporin resistance

    Microsoft Academic Search

    Aiman Zaher; Nevio Cimolai

    1998-01-01

    Enterobacterial repetitive intergenic consensus (ERIC) sequence polymerase chain reaction genotype profiles of Enterobacter cloacae were prepared for paired isolates which were obtained before and after the high level expression of the chromosomal cephalosporinase. These profiles were homologous within strain pairs which suggests that the acquired resistance does not lead to major chromosomal alterations. ERIC genotypes are therefore reliable markers in

  16. Protein expression profiles indicative for drug resistance of non-small cell lung cancer

    PubMed Central

    Volm, M; Koomägi, R; Mattern, J; Efferth, T

    2002-01-01

    Data obtained from multiple sources indicate that no single mechanism can explain the resistance to chemotherapy exhibited by non-small cell lung carcinomas. The multi-factorial nature of drug resistance implies that the analysis of comprising expression profiles may predict drug resistance with higher accuracy than single gene or protein expression studies. Forty cellular parameters (drug resistance proteins, proliferative, apoptotic, and angiogenic factors, products of proto-oncogenes, and suppressor genes) were evaluated mainly by immunohistochemistry in specimens of primary non-small cell lung carcinoma of 94 patients and compared with the response of the tumours to doxorubicin in vitro. The protein expression profile of non-small cell lung carcinoma was determined by hierarchical cluster analysis and clustered image mapping. The cluster analysis revealed three different resistance profiles. The frequency of each profile was different (77, 14 and 9%, respectively). In the most frequent drug resistance profile, the resistance proteins P-glycoprotein/MDR1 (MDR1, ABCB1), thymidylate-synthetase, glutathione-S-transferase-?, metallothionein, O6-methylguanine-DNA-methyltransferase and major vault protein/lung resistance-related protein were up-regulated. Microvessel density, the angiogenic factor vascular endothelial growth factor and its receptor FLT1, and ECGF1 as well were down-regulated. In addition, the proliferative factors proliferating cell nuclear antigen and cyclin A were reduced compared to the sensitive non-small cell lung carcinoma. In this resistance profile, FOS was up-regulated and NM23 down-regulated. In the second profile, only three resistance proteins were increased (glutathione-S-transferase-?, O6-methylguanine-DNA-methyltransferase, major vault protein/lung resistance-related protein). The angiogenic factors were reduced. In the third profile, only five of the resistance factors were increased (MDR1, thymidylate-synthetase, glutathione-S-transferase-?, O6-methylguanine-DNA-methyltransferase, major vault protein/lung resistance-related protein). British Journal of Cancer (2002) 87, 251–257. doi:10.1038/sj.bjc.6600463 www.bjcancer.com © 2002 Cancer Research UK PMID:12177790

  17. Electrically resistive coating for remediation (regeneration) of a diesel particulate filter and method

    DOEpatents

    Phelps, Amanda C. (Malibu, CA); Kirby, Kevin K. (Calabasas Hills, CA); Gregoire, Daniel J. (Thousand Oaks, CA)

    2012-02-14

    A resistively heated diesel particulate filter (DPF). The resistively heated DPF includes a DPF having an inlet surface and at least one resistive coating on the inlet surface. The at least one resistive coating is configured to substantially maintain its resistance in an operating range of the DPF. The at least one resistive coating has a first terminal and a second terminal for applying electrical power to resistively heat up the at least one resistive coating in order to increase the temperature of the DPF to a regeneration temperature. The at least one resistive coating includes metal and semiconductor constituents.

  18. Fabrication of an Electrically-Resistive, Varistor-Polymer Composite

    PubMed Central

    Ahmad, Mansor Bin; Fatehi, Asma; Zakaria, Azmi; Mahmud, Shahrom; Mohammadi, Sanaz A.

    2012-01-01

    This study focuses on the fabrication and electrical characterization of a polymer composite based on nano-sized varistor powder. The polymer composite was fabricated by the melt-blending method. The developed nano-composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FeSEM), and energy-dispersive X-ray spectroscopy (EDAX). The XRD pattern revealed the crystallinity of the composite. The XRD study also showed the presence of secondary phases due to the substitution of zinc by other cations, such as bismuth and manganese. The TEM picture of the sample revealed the distribution of the spherical, nano-sized, filler particles throughout the matrix, which were in the 10–50 nm range with an average of approximately 11 nm. The presence of a bismuth-rich phase and a ZnO matrix phase in the ZnO-based varistor powder was confirmed by FeSEM images and EDX spectra. From the current-voltage curves, the non-linear coefficient of the varistor polymer composite with 70 wt% of nano filler was 3.57, and its electrical resistivity after the onset point was 861 K?. The non-linear coefficient was 1.11 in the sample with 100 wt% polymer content. Thus, it was concluded that the composites established a better electrical non-linearity at higher filler amounts due to the nano-metric structure and closer particle linkages. PMID:23443085

  19. Incidence and Diversity of Antimicrobial Multidrug Resistance Profiles of Uropathogenic Bacteria

    PubMed Central

    Linhares, Inês; Raposo, Teresa; Rodrigues, António

    2015-01-01

    The aim of this study was to assess the most frequent multidrug resistant (MDR) profiles of the main bacteria implicated in community-acquired urinary tract infections (UTI). Only the MDR profiles observed in, at least, 5% of the MDR isolates were considered. A quarter of the bacteria were MDR and the most common MDR profile, including resistance to penicillins, quinolones, and sulfonamides (antibiotics with different mechanisms of action, all mainly recommended by the European Association of Urology for empirical therapy of uncomplicated UTI), was observed, alone or in association with resistance to other antimicrobial classes, in the main bacteria implicated in UTI. The penicillin class was included in all the frequent MDR profiles observed in the ten main bacteria and was the antibiotic with the highest prescription during the study period. The sulfonamides class, included in five of the six more frequent MDR profiles, was avoided between 2000 and 2009. The results suggest that the high MDR percentage and the high diversity of MDR profiles result from a high prescription of antibiotics but also from antibiotic-resistant genes transmitted with other resistance determinants on mobile genetic elements and that the UTI standard treatment guidelines must be adjusted for the community of Aveiro District.

  20. Numerical analysis for resist profile after thermal process in display manufacturing

    NASA Astrophysics Data System (ADS)

    Domnenko, Vitaliy; Stock, Hans-Jürgen; Shin, Sangmin; Ryu, Jonghyoek; Choi, Sung Won; Cho, Hyunwoo; Jeong, Eun-Soo; Choi, Jung-Hoe

    2014-03-01

    The screen size growth of mobile displays is accompanied with the drastically increased resolution. A display should have high pixel resolution to meet demanding readability and legibility expectations. The manufacturing process should be advanced to meet final device requirements. One of the important process steps is the post-development hardbake, where resist reflow is used to tune the final profile which influences subsequent process steps. Moreover, 3D resist profiles become one of critical design factors for mechanical and optical properties of display pixels. The resist reflow is the main time- and temperature-dependent effect of post-development bake process step. Since the resist is in transitional state (crystalline glassy/amorphous rubbery/viscous melt) the resist profile dynamics are very complex and predictive modeling is necessary. The model presented in this paper is based on a lattice-Boltzmann method, where the resist is considered as multicomponent (polymer-solvent) and multiphase (solid-liquid-vapor) mixture. Simulated resist profile dynamics with time are analyzed in dependency of material parameters (solvent diffusivity and evaporation rate, polymer solid fraction and adhesion with substrate). Temperature-dependent parameter descriptions are used for model calibration. Validation against experimental data shows good model consistency and predictability, demonstrating the benefit of simulation in process development and optimization.

  1. Can we quantify local groundwater recharge using electrical resistivity tomography?

    NASA Astrophysics Data System (ADS)

    Noell, U.; Günther, T.; Ganz, C.; Lamparter, A.

    2012-04-01

    Electrical resistivity tomography (ERT) has become a common tool to observe flow processes within the saturated/unsaturated zones. While it is still doubtful whether the method can reliably yield quantitative results the qualitative success has been shown in "numerous" examples. To quantify the rate of rainfall which reaches the groundwater table is still a problematic venture due to a sad combination of several physical and mathematical obstacles that may lead to huge errors. In 2007 an infiltration experiment was performed and observed using 3D array ERT. The site is located close to Hannover, Germany, on a well studied sandy soil. The groundwater table at this site was at a depth of about 1.3 m. The inversion results of the ERT data yield reliably looking pictures of the infiltration process. Later experiments nearby using tracer fluid and combined TDR and resistivity measurements in the subsurface strongly supported the assumption that the resistivity pictures indeed depict the water distributions during infiltration reliably. The quantitative interpretation shows that two days after infiltration about 40% of the water has reached the groundwater. However, the question remains how reliable this quantitative interpretation actually is. The first obstacle: The inversion of the ERT data gives one possible resistivity distribution within the subsurface that can explain the data. It is not necessarily the right one and the result depends on the error model and the inversion parameters and method. For these measurements we assume the same error for every single quadrupole (3%), applied the Gauss-Newton method and minimum length constraints in order to reduce the smoothing to a minimum (very small lambda). Numerical experiments showed little smoothing using this approach, and smoothing must be suppressed if preferential flow is to be seen. The inversion showed artefacts of minor amplitude compared with other inversion parameter settings. The second obstacle: The petrophysical function that relates the resistivity changes to water content changes is doubtful. This relationship was constructed by two ways; firstly by comparing in situ measured water contents and the ERT inversion results, secondly by laboratory measurements of soil samples taken at different depth. The results of these both methods vary; moreover, heterogeneity in the subsurface may cause an even greater variability of this relationship. For the calculation an "average" function was applied. The third obstacle: The pore water conductivity may change during the infiltration due to exchange of pore water. This effect is neglected for this experiment on account of the very similar resistivity of original pore water and infiltrated water. This effect, however, is of great importance if saline water is used for infiltration experiments. It will also hamper the quantitative interpretation if solution and precipitation processes within the soil during the infiltration are expected. The fourth obstacle: The disadvantageous shape of the function relating resistivity and water content. Unfortunately at high water contents only very little change in resistivity is observed if the water content increases or decreases, the function is steep only at small and medium water contents but very flat at high water contents. We conclude from the combination of these four obstacles that quantitative interpretation of recharge with ERT is possible only in fortunate cases. ERT can enable us to actually measure recharge processes. However, if the conditions are not fortunate, the interpretation of the ERT data will permit the conclusion whether there is recharge. The quantitative value will remain doubtful if no additional measurements are taken that narrow the uncertainties. Particularly TDR/resistivity measurements with the same probe are helpful to get the information about the mixing of the pore water.

  2. Material morphology and electrical resistivity differences in EPDM rubbers.

    SciTech Connect

    Yang, Nancy Y. C.; Domeier, Linda A.

    2008-03-01

    Electrical resistance anomalies noted in EPDM gaskets have been attributed to zinc-enriched surface sublayers, about 10-{micro}m thick, in the sulfur cured rubber material. Gasket over-compression provided the necessary connector pin contact and was also found to cause surprising morphological changes on the gasket surfaces. These included distributions of zinc oxide whiskers in high pressure gasket areas and cone-shaped features rich in zinc, oxygen, and sulfur primarily in low pressure protruding gasket areas. Such whiskers and cones were only found on the pin side of the gaskets in contact with a molded plastic surface and not on the back side in contact with an aluminum surface. The mechanisms by which such features are formed have not yet been defined.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  4. Monitoring Permeable Reactive Barriers using Electrical Resistance Tomography

    SciTech Connect

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

    2003-12-08

    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.

  5. Antibiotic resistant bacterial profiles of anaerobic swine lagoon effluent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although land application of swine 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. To better understand this, more data is ne...

  6. Antibiotic Resistant Bacterial Profiles of Anaerobic Swine Lagoon Effluent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although land application of swine 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 antibi...

  7. Novel applications of motif-directed profiling to identify disease resistance genes in plants

    PubMed Central

    2013-01-01

    Background Molecular profiling of gene families is a versatile tool to study diversity between individual genomes in sexual crosses and germplasm. Nucleotide binding site (NBS) profiling, in particular, targets conserved nucleotide binding site-encoding sequences of resistance gene analogs (RGAs), and is widely used to identify molecular markers for disease resistance (R) genes. Results In this study, we used NBS profiling to identify genome-wide locations of RGA clusters in the genome of potato clone RH. Positions of RGAs in the potato RH and DM genomes that were generated using profiling and genome sequencing, respectively, were compared. Largely overlapping results, but also interesting discrepancies, were found. Due to the clustering of RGAs, several parts of the genome are overexposed while others remain underexposed using NBS profiling. It is shown how the profiling of other gene families, i.e. protein kinases and different protein domain-coding sequences (i.e., TIR), can be used to achieve a better marker distribution. The power of profiling techniques is further illustrated using RGA cluster-directed profiling in a population of Solanum berthaultii. Multiple different paralogous RGAs within the Rpi-ber cluster could be genetically distinguished. Finally, an adaptation of the profiling protocol was made that allowed the parallel sequencing of profiling fragments using next generation sequencing. The types of RGAs that were tagged in this next-generation profiling approach largely overlapped with classical gel-based profiling. As a potential application of next-generation profiling, we showed how the R gene family associated with late blight resistance in the SH*RH population could be identified using a bulked segregant approach. Conclusions In this study, we provide a comprehensive overview of previously described and novel profiling primers and their genomic targets in potato through genetic mapping and comparative genomics. Furthermore, it is shown how genome-wide or fine mapping can be pursued by choosing different sets of profiling primers. A protocol for next-generation profiling is provided and will form the basis for novel applications. Using the current overview of genomic targets, a rational choice can be made for profiling primers to be employed. PMID:24099459

  8. Pyroclastic and Volcaniclastic Deposits Near Bishop, California: Geologic Controls on Near-Surface Electrical Resistivity and Radar Data

    NASA Astrophysics Data System (ADS)

    McGinnis, R. N.; Dinwiddie, C. L.; Stillman, D. E.; Heggy, E.; Grimm, R. E.

    2006-12-01

    Volcanic deposits near Bishop, California were recommended for study as potential Mars analogs (National Research Council Decadal Study report on Terrestrial Analogues to Mars, 2001). We report here on three geophysically distinct analog sites in the Bishop area—the nonwelded Bishop Tuff, the moderately welded Bishop Tuff, and a fluvially reworked volcaniclastic unit. We performed geological mapping and sampling, multielectrode resistivity profiling, and ground-penetrating radar (GPR) profiling to identify and interpret radar signatures obtained from these three analogs of near-surface lithologies. Specific gravity and electromagnetic properties will be determined from core and hand samples to assess the electrical response of these geologic units. Multielectrode resistivity survey results indicate the moderately welded Bishop Tuff has relatively high resistivities (average ?a= 964 ohm-m) and contains near-vertical, alluvium-filled joints. The nonwelded Bishop Tuff is relatively resistive (average ?a= 364 ohm-m), massive, and highly fractured near large- displacement faults. The reworked volcaniclastic unit is less resistive (average ?a= 207 ohm-m), contains primary ashfall deposits interbedded with layered fluvially reworked tuffaceous sediments, and is cut by horst- bounding, meter-scale displacement normal faults. This study provides a basis for correlating physical attributes (i.e., lithology and deformation features) with measured data (i.e., resistivity and GPR data). Survey results indicate that multielectrode resistivity is a particularly instructive method to use with GPR surveys for constraining interpretations and for estimating signal loss from attenuation (e.g., Grimm et al., this meeting). This integrated approach provides a deeper understanding of the electrical and radar properties within terrestrial analogs of Mars.

  9. ELECTRICAL RESISTIVITY OF SOME LIQUID CADMIUM ANTIMONY ALLOYS AS A FUNCTION OF TEMPERATURE

    E-print Network

    Paris-Sud XI, Université de

    L-93 ELECTRICAL RESISTIVITY OF SOME LIQUID CADMIUM ANTIMONY ALLOYS AS A FUNCTION OF TEMPERATURE J The electrical resistivity of several Cd1-xSbx antimony rich alloys has been investiga- ted between the liquidus the measurements to high tempera- tures (up to 900 OC) for the antimony rich alloys for which few measurements

  10. Shape memory alloy servo actuator system with electric resistance feedback and application for active endoscope

    Microsoft Academic Search

    Koji Ikuta; M. Tsukamoto; Shigeo Hirose

    1988-01-01

    A control system for a shape memory alloy (SMA) servo actuator, and its application to a unique medical tool, are considered. It is thought that the electric resistance value of an SMA can be utilized to monitor the transformation of the SMA directly. Therefore, an antagonistic transformation control scheme using electric resistance feedback is proposed and is verified by several

  11. Resistance of the insulation of the stator winding of water-filled submersible electric motor

    Microsoft Academic Search

    V. F. Fedorov; O. N. Nikiforova; V. T. Kolesnikova

    1987-01-01

    The authors analyzed the data on the resistance of the insulation of the stator winding of water-filled electric motors obtained in tests of 560 series produced machines in the course of ten years. The stator windings were made of conductors PEVVP and PVDP. The authors conclude that the resistance of the insulation of the stator windings of series produced electric

  12. Electrical resistivity of graphitized ultra-disperse diamond and onion-like carbon

    Microsoft Academic Search

    V. L. Kuznetsov; Yu. V. Butenko; A. L. Chuvilin; A. I. Romanenko; A. V. Okotrub

    2001-01-01

    Here we present the result of measurements of electrical resistivity of ultra-disperse diamonds (UDD) with different graphitization degrees and onion-like carbon (OLC) prepared by vacuum annealing of UDD samples at various fixed temperatures. Intermediate samples contain particles with a diamond core covered by closed curved graphitic shells. The temperature dependence of electrical resistivity ?(T) of these structures is characteristic for

  13. MECHANISMS OF THE ELECTRICAL RESISTIVITY OF RARE EARTH ALLOYS AT LOW TEMPERATURES

    Microsoft Academic Search

    Smidt; F. A. Jr

    1962-01-01

    The existence of complete solid solubility in the alloy systems Gd-- Lu, ; Tb- Lu, and Gd- Er was established by means of x-ray diffraction and electrical ; resistivity methods. The electrical resistivity was measured as a function of ; temperature from 4.2 to 310 deg K for twelve alloys in these systems and the data ; were analyzed to

  14. Electrokinetic Characterization of Porous Plugs from Streaming Potential Coupled with Electrical Resistance Measurements

    Microsoft Academic Search

    A. Szymczyk; P. Fievet; A. Foissy

    2002-01-01

    The zeta potential of mixed nickel–iron oxide particles is evaluated by a new laboratory instrument. This latter allows the measurement of streaming potential together with the electrical resistance of porous plugs. The conductivity of electrolyte inside plug (pore conductivity) is deduced from electrical resistance measurements and is used together with streaming potential to evaluate the zeta potential by accounting for

  15. Electrical Resistance Tomography Field Trials to Image CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Newmark, R.

    2003-12-01

    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.

  16. Combining Inverted Echo Sounder and Horizontal Electric Field Recorder Measurements to Obtain Absolute Velocity Profiles

    Microsoft Academic Search

    Christopher S. Meinen; Douglas S. Luther; D. Randolph Watts; Karen L. Tracey; Alan D. Chave; James Richman

    2002-01-01

    Profiles of absolute velocity are difficult to obtain in the ocean, especially over long periods of time at the same location. This paper presents a method of estimating full water column absolute horizontal velocity profiles as a function of time by combining historical hydrography with the measurements from two separate instruments, the inverted echo sounder (IES) and the horizontal electric

  17. Electric-field-modulated nonvolatile resistance switching in VO?/PMN-PT(111) heterostructures.

    PubMed

    Zhi, Bowen; Gao, Guanyin; Xu, Haoran; Chen, Feng; Tan, Xuelian; Chen, Pingfan; Wang, Lingfei; Wu, Wenbin

    2014-04-01

    The electric-field-modulated resistance switching in VO2 thin films grown on piezoelectric (111)-0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (PMN-PT) substrates has been investigated. Large relative change in resistance (10.7%) was observed in VO2/PMN-PT(111) hererostructures at room temperature. For a substrate with a given polarization direction, stable resistive states of VO2 films can be realized even when the applied electric fields are removed from the heterostructures. By sweeping electric fields across the heterostructure appropriately, multiple resistive states can be achieved. These stable resistive states result from the different stable remnant strain states of substrate, which is related to the rearrangements of ferroelectric domain structures in PMN-PT(111) substrate. The resistance switching tuned by electric field in our work may have potential applications for novel electronic devices. PMID:24634978

  18. Application of electrical resistivity tomography to map lithological differences and subsurface structures (Eastern Sudetes, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Stan, Dominika; Stan-K?eczek, Iwona

    2014-09-01

    The aim of this study is to determine the subsurface lithological variability and thickness of each metamorphic rocks unit by means of geophysical methods, which were presented within the framework of SEDIBUD. Research was performed on the ridge and the steep eastern slope of the Orlik massif (1204 m) in the Hrubý Jesenik range of the Eastern Sudetes, the Czech Republic. To obtain a spatial image of a geological rock mass, the non-invasive and relatively rapid method of electrical resistivity tomography (ERT) was used, which resulted in the creation of six profiles using the Dipole-Dipole and Wenner-Schlumberger arrays. As complementary methods, vertical electrical sounding (VES) and seismic refraction tomography were chosen. Fifteen measuring points along two profiles obtained by vertical electrical sounding allowed the determination of the following in the vertical section layers of different resistivity and thickness at direct points in contact primarily with Devonian quartzite rocks and weathered covers. In a series of field studies, a four-layered rock mass was examined in which the first layer is of fine-grained materials with medium- and large-size clasts, the second layer is quartzite, the third is gneiss and the fourth is phyllite. The five profiles measured by seismic refraction tomography made it possible to draw the boundary between the studied phyllites, gneisses and quartzites. In addition, geophysical surveys and the results of mineralogical composition analysis allowed us to determine the nature and thickness of the weathered layers present on the massif area, which, in the upper sections, are predominantly a clayey loam partially covered with blocks. The inclination of the slope is associated with an increase in the fraction of coarse material. The majority of the thickness of these layers is related to the local flattened surfaces and the presence of numerous streams, which contributed to the accumulation of the sediments that were also transported from the ridge area. This diversity indicates notably active slope processes during the Pleistocene. The results confirmed the usefulness of geophysical methods to identify the geological structure of rocks with highly variable lithology with faults and folding features.

  19. Time-Lapse Electrical Resistivity Surveys of the Intertidal Zone: Implications for Submarine Groundwater Discharge

    NASA Astrophysics Data System (ADS)

    Durand, J. M.; Wong, T.

    2013-12-01

    Submarine groundwater discharge (SGD) is now widely recognized as a crucial contributor to surface water as it provides a pathway for nutrients and contaminants that can significantly impact coastal ecosystems. Field measurements in the vicinity of the freshwater/seawater interface (FSI) have shown that the spatio-temporal distribution of SGD can be highly heterogeneous. Some numerical models have identified 3 regions (a density-driven circulation cell offshore, an upper saline plume and a freshwater tube in the intertidal zone) which seem to persist over time, such that the distinct regions can be recognized in simulations that average the numerically predicted salinity profiles over the tidal phases. The size and shape of each region are influenced by factors such as the tidal and wave loading, inland hydraulic gradient, beach geometry and aquifer properties. There is a paucity of field data at the FSI on the evolution of the salinity profile during a tidal cycle. To characterize the spatio-temporal heterogeneities of the FSI and compare with numerical predictions, we used electrical resistivity as a proxy for salinity. Electrical resistivity surveys were acquired during a 12-hour cycle in a tidally dominated environment. On September 12 2012, at West Neck Bay (Shelter Island, NY), a 33.4 m long stationary cable with 56 electrodes was extended over land and sea to image the intertidal zone. Hourly measurements were conducted over a full tidal cycle. Our measurements indicate fundamentally different scenarios during high and low tide. At low tide, our resistivity data suggest a strong influx of freshwater from land, forming a plume that rises up and contributes significantly to SGD in the intertidal zone. We also observed the occurrence of 3 regions somewhat analogous to the numerical predictions. However, at high tide, instead of these distinct regions, we observed a diffuse mixing zone that extended along the water/sediment interface and overlaid the freshwater from land. Point measurements of seepage rates and salinity are in basic agreement with the two scenarios. It should also be noted that the phase-averaged section obtained with the resistivity surveys resembles the high tide scenario and therefore differs from the phase-averaged simulations.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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.

  1. Electrical Resistivity of Silicate Glass Melts Calculation Based on the SciGlass Database

    Microsoft Academic Search

    Alexander Fluegel; David A. Earl; Arun K. Varshneya

    The relation between the chemical composition and the electrical resistivity (= 1\\/conductivity) of silicate glass melts at temperatures of 1000 oC to 1400 oC from the SciGlass Database was analyzed statistically. A model including ionic interactions was developed that permits calculating the glass melt electrical resistivity with a standard error of about 0.06 on the logarithmic resistivity scale in ??cm.

  2. Application of two electrical methods for the rapid assessment of freezing resistance in Salix eriocephala

    Microsoft Academic Search

    V. Tsarouhas; W. A. Kenney; L. Zsuffa

    2000-01-01

    The importance of early selection of frost-resistant Salix clones makes it desirable to select a rapid and accurate screening method for assessing freezing resistance among several genotypes. Two electrical methods, stem electrical impedance to 1 and 10kHz alternating current, and electrolyte leakage of leaf tissue, were evaluated for detecting freezing resistance on three North America Salix eriocephala Michx., clones after

  3. Study of Electrical Resistivity of Powder Materials Obtained by Oxidation of Hard Alloys

    Microsoft Academic Search

    V. P. Nesterenko; K. P. Aref'ev; V. I. Merkulov; A. A. Kondratyuk; A. V. Petrov

    2001-01-01

    An electrical resistivity of oxide powder materials obtained by high-temperature heating of hard-alloy tool materials has been measured. The resistivity of oxide powder increases with increasing cobalt content in raw hard alloys as well as the oxidation temperature. On the contrary, the increase of concentration of titanium and tantalum carbides is accompanied by the resistivity reduction. The increase of pressure

  4. Plasmonic Nanopore for Electrical Profiling of Optical Intensity Magnus P. Jonsson and Cees Dekker*

    E-print Network

    Dekker, Cees

    Plasmonic Nanopore for Electrical Profiling of Optical Intensity Landscapes Magnus P. Jonsson-limited resolution. This is achieved with a novel device, a plasmonic nanopore, which combines a plasmonic bowtie the plasmonic heating, which we measure electrically through changes in the ionic conductance of the nanopore

  5. Hydrogeophysical Characterization of a Texas Expansive Heavy Clay Soil (Vertisol) Using Electrical Resistivity Measurements

    NASA Astrophysics Data System (ADS)

    Amidu, S. A.; Dunbar, J. A.

    2006-05-01

    We applied field and laboratory electrical resistivity measurements to characterize seasonal wetting and drying of a Texas Vertisol. Vertisols are complex soils characterized by high clay content (>30%), high shrink/swell potential, microrelief expression of subsurface soil dynamics (gilgai), and low hydraulic conductivity. A total of thirty-three multi-electrode resistivity profiling lines were taken along the same profile between April 27, 2005 to February 26, 2006 using combined dipole-dipole and Schlumberger electrode configurations, at electrode spacings of 0.5 m. The field site is located at the USDA - Grassland Soil and Water Research Station, near Riesel, Texas. The profiles were 17.5 m long and intersected two sets of microhighs and microlows of the gilgai. Inversion of resistivity data was done by a rapid least-square technique. In order to constrain and evaluate field results, in-situ measurement of soil-moisture was made using impedance probes and auger sampling. We designed a laboratory experiment to measure variations of soil moisture with resistivity using soil samples. We also made in-situ measurement of crack depths, and the results were incorporated into the laboratory and field data. The laboratory results were used to estimate petrophysical parameters for the Vertisol using a modified Archie's relationship, and to calibrate field results. Results of field surveys show that the upper 1.4 m of the Vertisol can be divided into three distinct soil moisture regimes: the upper zone (0 to ~0.5 m) which is the most dynamic with regards to wetting and drying in the Vertisol; the middle zone (~0.5 m to ~1.1 m) which is relatively saturated and less dynamic, and the lower zone (below ~1.1 m) which is relatively less saturated compared to the middle layer. Seasonal hydrodynamics of the Vertisol is a complex interrelationship of by-pass flow through cracks, microrelief variability and hydraulic conductivity of the soil. We attribute gilgai formation to periodic expansion of the "wetter" depth interval in a manner analogous to formation of mullions in contracting sedimentary sections.

  6. Electrical resistance measurements of highly inhibited SiC coated carbon-carbon laminates

    E-print Network

    Parker, Paul Albert

    1998-01-01

    Figure 26. Boron Concentrations for Four Oxidized Carbon-Carbon Specimens . . . . . 44 Figure 27. Electrical Resistance . . Figure 28. Electrical Resistance versus Percent Mass Loss for Eighteen Specimens . . . . Figure 29, Representative Electrical... above 1093'C, T-300 carbon fibers, carbon matrix, and the oxidation inhibitor boron carbide (B4C), which chemically reacts with oxygen and becomes boric oxide (BsOs). Each of these four components connibutes to the oxidation characterization...

  7. Velocity, temperature, and electrical conductivity profiles in hydrogen-oxygen MHD duct flows

    NASA Technical Reports Server (NTRS)

    Greywall, M. S.; Pian, C. C. P.

    1978-01-01

    This paper presents results of two-dimensional duct flow computations for radial distributions of velocity, temperature, and electrical conductivity. Calculations were carried out for the flow conditions representative of NASA Lewis hydrogen-oxygen combustion driven MHD duct. Results are presented for two sets of computations: (1) profiles of developing flow in a smooth duct, and (2) profiles of fully developed pipe flow with a specified streamwise shear stress distribution. The predicted temperature and electrical conductivity profiles for the developing flows compared well with available experimental data.

  8. Electric field tomography for contactless imaging of resistivity in biomedical applications

    Microsoft Academic Search

    A. V. Korjenevsky

    2004-01-01

    The technique of contactless imaging of resistivity distribution inside conductive objects, which can be applied in medical diagnostics, has been suggested and analyzed. The method exploits the interaction of a high-frequency electric field with a conductive medium. Unlike electrical impedance tomography, no electric current is injected into the medium from outside. The interaction is accompanied with excitation of high-frequency currents

  9. Detecting leaks in hydrocarbon storage tanks using electrical resistance tomography

    SciTech Connect

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

    1995-04-03

    Large volumes of hydrocarbons are stored worldwide in surface and underground tanks. It is well documented [1] that all too often these tanks are found to leak, resulting in not only a loss of stored inventory but, more importantly, contamination to soil and groundwater. Two field experiments are reported herein to evaluate the utility of electrical resistance tomography (ERT) for detecting and locating leaks as well as delineating any resulting plumes emanating from steel underground storage tanks (UST). Current leak detection methods for single shell tanks require careful inventory monitoring, usually from liquid level sensors within the tank, or placement of chemical sensors in the soil under and around the tank. Liquid level sensors can signal a leak but are limited in sensitivity and, of course, give no information about the location or the leak or the distribution of the resulting plume. External sensors are expensive to retrofit and must be very densely spaced to assure reliable detection, especially in heterogeneous soils. The rational for using subsurface tomography is that it may have none of these shortcomings.

  10. Electrical resistivity of CeZn11 under pressure

    NASA Astrophysics Data System (ADS)

    Taufour, Valentin; Kim, Stella K.; Hodovanets, Halyna; Bud'Ko, Sergey L.; Canfield, Paul C.

    2013-03-01

    In most Ce-based intermetallic compounds, the magnetic exchange is assumed to be due to the RKKY interaction. This interaction competes with the Kondo interaction, leading to the suppression of the magnetic order and the possibility of field and/or pressure induced quantum criticality. In order to study this competition in CeZn11, a compound that orders antiferromagnetically below TN= 2 K, we performed electrical resistivity measurements on a single crystal of CeZn11 under pressure up to 5 GPa in a Bridgman pressure cell modified to use a liquid pressure transmitting medium (1:1 mixture of n-pentane: iso-pentane). TN(p) slightly increases and approaches a broad maximum in the studied pressure range. At ambient pressure, the antiferromagnetic order is suppressed by a magnetic field along the [1,1,0] direction of the tetragonal crystal structure. The temperature versus magnetic field phase diagram at 5 GPa will be compared to the one at ambient pressure.

  11. Research on nonlinear feature of electrical resistance of acupuncture points.

    PubMed

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

    2012-01-01

    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. PMID:23346191

  12. Electrical resistance sensors record spring flow timing, Grand Canyon, Arizona

    USGS Publications Warehouse

    Adams, E.A.; Monroe, S.A.; Springer, A.E.; Blasch, K.W.; Bills, D.J.

    2006-01-01

    Springs along the south rim of the Grand Canyon, Arizona, are important ecological and cultural resources in Grand Canyon National Park and are discharge points for regional and local aquifers of the Coconino Plateau. This study evaluated the applicability of electrical resistance (ER) sensors for measuring diffuse, low-stage (<1.0 cm) intermittent and ephemeral flow in the steep, rocky spring-fed tributaries of the south rim. ER sensors were used to conduct a baseline survey of spring flow timing at eight sites in three spring-fed tributaries in Grand Canyon. Sensors were attached to a nearly vertical rock wall at a spring outlet and were installed in alluvial and bedrock channels. Spring flow timing data inferred by the ER sensors were consistent with observations during site visits, with flow events recorded with collocated streamflow gauging stations and with local precipitation gauges. ER sensors were able to distinguish the presence of flow along nearly vertical rock surfaces with flow depths between 0.3 and 1.0 cm. Laboratory experiments confirmed the ability of the sensors to monitor the timing of diffuse flow on impervious surfaces. A comparison of flow patterns along the stream reaches and at springs identified the timing and location of perennial and intermittent flow, and periods of increased evapotranspiration.

  13. Electrical resistance sensors record spring flow timing, Grand Canyon, Arizona.

    PubMed

    Adams, Eric A; Monroe, Stephen A; Springer, Abraham E; Blasch, Kyle W; Bills, Donald J

    2006-01-01

    Springs along the south rim of the Grand Canyon, Arizona, are important ecological and cultural resources in Grand Canyon National Park and are discharge points for regional and local aquifers of the Coconino Plateau. This study evaluated the applicability of electrical resistance (ER) sensors for measuring diffuse, low-stage (<1.0 cm) intermittent and ephemeral flow in the steep, rocky spring-fed tributaries of the south rim. ER sensors were used to conduct a baseline survey of spring flow timing at eight sites in three spring-fed tributaries in Grand Canyon. Sensors were attached to a nearly vertical rock wall at a spring outlet and were installed in alluvial and bedrock channels. Spring flow timing data inferred by the ER sensors were consistent with observations during site visits, with flow events recorded with collocated streamflow gauging stations and with local precipitation gauges. ER sensors were able to distinguish the presence of flow along nearly vertical rock surfaces with flow depths between 0.3 and 1.0 cm. Laboratory experiments confirmed the ability of the sensors to monitor the timing of diffuse flow on impervious surfaces. A comparison of flow patterns along the stream reaches and at springs identified the timing and location of perennial and intermittent flow, and periods of increased evapotranspiration. PMID:16961484

  14. Molecular characterization and antibiotic resistance profiling of Salmonella isolated from retail Turkey meat products.

    PubMed

    Fakhr, Mohamed K; Sherwood, Julie S; Thorsness, Jessica; Logue, Catherine M

    2006-01-01

    Contaminated poultry meat has been identified as one of the principal foodborne sources of Salmonella. Molecular characterization of Salmonella is important in addressing methods to control this pathogen. Seventy-four retail turkey meat samples were collected from various stores in Fargo, North Dakota in the fall of 2003. Salmonella was recovered from 30 samples using the standard conventional culture method (FSIS, USDA). Isolated Salmonella were characterized by serotyping, pulsed-field gel electrophoresis (PFGE) analysis, plasmid analysis, and antibiotic resistance profiling. Five serotypes were identified among the isolates: Newport (n = 12), Hadar (n = 8), Heidelberg (n = 7), 4,12:nonmotile (n = 2), and Reading (n = 1). XbaI PFGE analysis revealed 13 PFGE types and succeeded in grouping the isolates according to their serotypes. Plasmid profiling identified 5 plasmid types (with 1 or 2 plasmids) among eleven isolates that harbored plasmids. Seventeen isolates were resistant to antibiotics. The Heidelberg serotype showed resistance to multiple antibiotics: 1 isolate had resistance to gentamicin, sulfamethoxazole, and streptomycin, and 6 isolates had resistance to tetracycline, gentamycin, sulfamethoxazole, kanamycin, and streptomycin. The Hadar serotype isolates were resistant to 2 or 3 antibiotics: tetracycline and streptomycin (1 isolate); tetracycline and kanamycin (1 isolate); and tetracycline, kanamycin, and streptomycin (6 isolates). The 4,12:nonmotile serotype isolates showed resistance to tetracycline only. The Newport and the Reading serotypes were susceptible to all 16 of the antimicrobials tested. PMID:17199518

  15. Electrical Properties of Materials for Elevated Temperature Resistance Strain Gage Application. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen

    1987-01-01

    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 suggested as good candidates for high temperature resistance strain gage applications.

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

    DOEpatents

    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

    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.

  17. LTCC resistors and resistive temperature sensors - chosen electrical and stability properties

    Microsoft Academic Search

    A. Dziedzic; L. Golonka; M. Hrovat; J. Kita; D. Belavic

    2005-01-01

    This paper presents the correlation between processing conditions and electrical (sheet resistance, resistance vs temperature dependence) and long-term stability (relative changes in resistance (DeltaR\\/R0) as well as changes in the temperature coefficient of resistance (DeltaTCR) or thermistor constant (DeltaB) properties of surface and buried LTCC resistors as well as NTC and PTC thermistors. All analyzed components (made from 100 ohm\\/sq.

  18. On the Intensity Profile of Electric Lamps and Light Bulbs

    ERIC Educational Resources Information Center

    Bacalla, Xavier; Salumbides, Edcel John

    2013-01-01

    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…

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

    PubMed

    Chai, Ru-Yuan; Lee, Chow-Yang

    2010-04-01

    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

  20. Determination of surface electric charge profile in pyroelectric crystals

    NASA Astrophysics Data System (ADS)

    Ghaderi, R.; Davani, F. Abbasi

    2014-12-01

    Pyroelectric crystals are used to produce high energy self-focused electron beams. Here, an experimental analysis in combination with simulation studies will be reported to investigate possible sources of this effect. In the experiments, the surface of crystal was divided into six separated parts and the rate of surface electric charge production was measured accordingly. A non-steady and spatially non-uniform distribution of the surface charge generation was observed, in which it tends to a uniform distribution in the course of experiment. The obtained surface electric charges from the experiments were used to simulate the electric field and potential around the crystal by COMSOL Multiphysics. It was observed that emitted electrons from the crystal surface were focused, and the non-uniformity in spatial charge is responsible for this phenomenon.

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

    NASA Astrophysics Data System (ADS)

    Jiang, Jinbao; Xiao, Huigang; Li, Hui

    2013-04-01

    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.

  2. Electrical permittivity and resistivity time lapses of multiphase DNAPLs in a lab test

    NASA Astrophysics Data System (ADS)

    Orlando, Luciana; Renzi, Beatrice

    2015-01-01

    Dense Non-Aqueous Phase Liquids (DNAPLs) induce variation in electromagnetic characteristics of the ground, e.g., electric permittivity and resistivity. The most used indirect methods in the mapping of these physical characteristics are electrical resistivity and ground penetrating radar. To better understand the effect of DNAPL release on electrical permittivity and resistivity in a water saturated medium, we carried out a controlled laboratory experiment where the host material was simulated by glass beads and the DNAPL by HFE-7100 (hydrofluoroether). The experiment measured the electric resistivity and permittivity of each fluid, the multiphase fluid system, and the host material, along with time-lapse electrical resistivity and GPR measurements in a controlled cell. We found that the different phases of DNAPL within a saturated medium (free, dissolved, and gaseous phase) affect the physical characteristics differently. The reflection pull-up behind contaminated sediments, which is normally detected by GPR, was mainly inferred from the HFE free phase. The dissolved phase causes small variations in electric permittivity not usually readily detected by GPR measurements. Both the dissolved and free HFE phases induce variation in resistivity. The study showed that GPR and electrical resistivity differ in sensitivity to the different HFE phases, and can be complementary in the characterization of DNAPL contaminated sites.

  3. Plume and lithologic profiling with surface resistivity and seismic tomography.

    PubMed

    Watson, David B; Doll, William E; Gamey, T Jeffrey; Sheehan, Jacob R; Jardine, Philip M

    2005-01-01

    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. PMID:15819938

  4. Antimicrobial resistance profiling and molecular subtyping of Campylobacter spp. from processed turkey

    PubMed Central

    2009-01-01

    Background Campylobacter is a major cause of human disease worldwide and poultry are identified as a significant source of this pathogen. Most disease in humans is associated with the consumption of contaminated poultry or cross-contamination with other foods. The primary drugs of choice for treatment of human campylobacteriosis include erythromycin and ciprofloxacin. In this study, we investigated the prevalence of resistance to erythromycin and ciprofloxacin in Campylobacter isolates recovered from turkey carcasses at two processing plants in the Upper Midwest US. Further analysis of a subset of isolates was carried out to assess resistance and genotype profiles. Results Campylobacter isolates from plant A (n = 439; including 196 C. coli and 217 C. jejuni) and plant B (n = 362, including 281 C. coli and 62 C. jejuni) were tested for susceptibility to ciprofloxacin and erythromycin using agar dilution. C. coli were more frequently resistant than C. jejuni in both plants, including resistance to ciprofloxacin (28% of C. jejuni and 63% of C. coli, plant B; and 11% of C. coli, plant A). Erythromycin resistance was low among C. jejuni (0% plant A and 0.3% plant B) compared to C. coli (41%, plant A and 17%, plant B). One hundred resistant and susceptible isolates were selected for additional antimicrobial susceptibility testing, restriction fragment length polymorphism analysis of the flaA gene (fla typing), and pulsed-field gel electrophoresis (PFGE). Fla-PFGE types obtained (n = 37) were associated with a specific plant with the exception of one type that was isolated from both plants. C. coli isolates (n = 65) were grouped into 20 types, while C. jejuni isolates (n = 35) were grouped into 17 types. Most isolates with identical fla-PFGE patterns shared identical or very similar antimicrobial resistance profiles. PFGE alone and composite analysis using fla-PFGE with resistance profiles separated C. jejuni and C. coli into distinct groups. Conclusion Ciprofloxacin and erythromycin resistance in Campylobacter recovered from processed turkey occurred more frequently among C. coli than C. jejuni. Fla-PFGE types were associated with a particular species, antimicrobial resistance profiles, and a specific plant. Molecular subtyping in this study provided more information about the relationships among antimicrobial-resistant Campylobacter at the processing level. PMID:19772592

  5. Bedrock detection beneath river terrace deposits using three-dimensional electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Chambers, J. E.; Wilkinson, P. B.; Wardrop, D.; Hameed, A.; Hill, I.; Jeffrey, C.; Loke, M. H.; Meldrum, P. I.; Kuras, O.; Cave, M.; Gunn, D. A.

    2012-12-01

    We describe the use of a fully volumetric geophysical imaging approach, three-dimensional electrical resistivity (3D ERT), for bedrock detection below mixed sand and gravel deposits typical of fluvial valley-fill terraces. We illustrate the method through an analysis of terrace deposits of the Great Ouse River (UK), where up to 4 m of sand and gravel have filled the valley bottom during the latest Pleistocene. We use an edge detector to identify the steepest gradient in first-derivative resistivity profiles, which yields an estimate of bedrock depth (verified by drilling) to a precision better than 0.2 m (average) and 0.4 m (standard deviation). Comparison of a range of drilling techniques at the site has revealed that borehole derived interface depths suffered from levels of uncertainty similar to those associated with the 3D ERT - indicating that the reliability of bedrock interface depths determined using these two approaches is comparable in this case. The 3D ERT method provides a high spatial resolution that enabled a previously unknown erosional bedrock structure, associated with the change from deeper first terrace to second terrace deposits, to be identified in the Great Ouse valley. The method provides a relatively quick method to quantify terrace fill volume over large sites to a greater degree of precision than currently available.

  6. Electrical resistivity imaging for characterizing dynamic hydrologic systems

    NASA Astrophysics Data System (ADS)

    Amidu, Sikiru Adetona

    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.

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

    USGS Publications Warehouse

    Zhu, J.; Currens, J.C.; Dinger, J.S.

    2011-01-01

    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. ?? 2011 Elsevier B.V.

  8. Shunt haemodynamics and extracorporeal dialysis: an electrical resistance network analysis

    Microsoft Academic Search

    M. J. C. van Gemert; C. M. A. Bruyninckx; M. J. H. Baggen

    1984-01-01

    A time-dependent resistance model is used to study haemodynamic aspects of haemodialysis treatment. In the first part of the paper one model circuit, consisting of a pressure source, upstream and downstream resistances and a branching resistance, is shown to represent the haemodynamics of any type of arteriovenous fistula (AVF). Simple algebraic relations are derived for the haemodynamic determinants of AVFs,

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

    SciTech Connect

    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

    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.

  10. Electrical resistance of Fe-Zr and Fe-Ni-Zr amorphous alloys under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Shirakawa, K.; Fukamichi, K.; Kaneko, T.; Masumoto, T.

    1983-08-01

    The effect of pressure on the electrical resistance of Fe 90Zr 10 and (Fe 0.96Ni 0.04) 90Zr 10 amorphous alloys has been investigated. The minimum point in the electrical resistance versus temperature curve shifts toward lower temperature range with increasing hydrostatic pressure, corresponding to the shift of the Curie temperature. The decrement of the electrical resistance below the Curie temperature Tc is about twice that above Tc, suggesting a large compressibility in the ferromagnetic state of the amorphous Invar alloys.

  11. A Novel Remote Detection Method of Illegal Electricity Usage Based on Smart Resistance

    Microsoft Academic Search

    Byambasuren Bat-Erdene; Sang-Yep Nam; Dong-Han Kim

    \\u000a A power delivery system that uses power line communication can communicate with other electrical systems, monitor the quality\\u000a of electrical energy, and create an economical solution for automatic meter reading. If we use a smart meter with the smart\\u000a resistance proposed in this paper, we can easily add an illegal electricity usage detection capability to an electrical power\\u000a delivery system

  12. Electrical resistivity of some Zintl phase and the precursors

    SciTech Connect

    Wolfe, L.

    1990-09-21

    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).

  13. Characterizing heterogeneous coastal groundwater pathways using multi-scale onshore-to-offshore electrical resistivity surveys

    NASA Astrophysics Data System (ADS)

    Befus, K. M.; Cardenas, M.; Tait, D. R.; Erler, D.

    2013-12-01

    Electrical resistivity (ER) imaging techniques are useful for investigating porewater salinity distributions and dynamics within coastal environments. However, complex coastal geology can obscure the hydrologic target of ER surveys. We investigated the geologic controls on groundwater pathways in Rarotonga, a high volcanic island with a carbonate fringe. We used three ER survey configurations to explore this hydrogeologic setting: 1) waterborne, continuous resistivity profiling in the lagoon, 2) submerged cable surveys across the terrestrial-marine interface, and 3) traditional surveys on land. We designed overlapping portions of these surveys to reveal differences in how the deployment methods image subsurface ER structure. Using both the field data and forward modeling, we quantified the resolvability of ER features imaged by overlapping configurations, where the sensitivity changed both as a function of electrode spacing and boundary conditions (i.e. influence of seawater). Waterborne ER results revealed large scale variations in the ER structure of the lagoon geology. These heterogeneities are products of Rarotonga's volcanic history and reef diagenesis that change both the electrical signature and hydrogeologic properties of the subsurface. Time-lapse, submersed ER surveys imaged groundwater salinity dynamics and resolved select ER features more effectively than the waterborne surveys. Terrestrial ER surveys traced the extent of the freshwater lens and the transition from the unsaturated-saturated conditions, i.e., the water table. The ER responses of the three field configurations were concordant but imaged different scales hydrogeologic variability. The unique spatial signatures of both methodology and the geologic setting must be incorporated into future coastal ER applications.

  14. [Characterization and expression profiling of a novel cereal cyst nematode resistance gene analog in wheat].

    PubMed

    Zhai, X G; Zhao, T; Liu, Y H; Long, H; Deng, G B; Pan, Z F; Yu, M Q

    2008-01-01

    Based on the conserved regions of known resistance genes, a NBS-LRR type CCN resistance gene analog was isolated from the CCN resistant E-10 near isogenic lines (NILs) of wheat, designated as CreZ (GenBank Acc. N: EU327996). It contained a complete ORF that was 2775 bp in length and encoded 924 amino acids. Sequence comparison indicated that it shared 92% nucleotide and 87% amino acid identity with those of the known CCN-resistance gene Cre3 and had similar characteristic conserved motifs as those in other established NBS-LRR disease resistance genes. The expression profiling of CreZ indicated that it was specifically expressed in the roots of resistant plants and real-time PCR analysis demonstrated that expression levels drastically increased when the plants were inoculated with cereal cyst nematodes. It could be inferred, then, that CreZ belongs to the NBS-LRR resistance gene family and is a candidate gene for potential resistance to the cereal cyst nematode. PMID:19140329

  15. Applying petrophysical models to radar travel time and electrical resistivity tomograms: Resolution-dependent limitations

    E-print Network

    Singha, Kamini

    Applying petrophysical models to radar travel time and electrical resistivity tomograms: Resolution; however, there is increasing interest in using petrophysical models to convert tomograms to quantitative, water content, and salinity). Unfortunately, petrophysical estimation based on tomograms is complicated

  16. Composite Materials with Distinctive Behaviors under High Electric Fields: I - Material Switches to 'High Resistive' State

    NASA Technical Reports Server (NTRS)

    Javadi, H.

    1994-01-01

    Electrically conductive silver filled epoxy ECF-563 preform, sandwiched between gold contact pads exhibits intermittent current-voltage characteristics with switching to 'high resistive' state under applied bias voltage.

  17. Forced magnetic reconnection in a plasma sheet with localized resistivity profile excited by lower hybrid drift type instability

    NASA Technical Reports Server (NTRS)

    Hoshino, M.

    1991-01-01

    A forced magnetic reconnection process with a temporal evolution of resistivity is studied for a plasma sheet with a nonuniform resistivity profile based on the nonlocal mode structure of the lower hybrid drift type instability. The growth rate of the mode found is almost independent of the resistivity at the neutral sheet, but depends on the resistivity of the region of maximum density gradient away from the neutral sheet. This is studied by using both a nonlinear numerical MHD simulation and a linear theory. The mode may be relevant to the prevalent theoretical concept of MHD reconnection and the localized anomalous resistivity profile based on the lower hybrid drift instability.

  18. Modeling the electrical resistivity of deformation processed metal-metal composites

    SciTech Connect

    Tian, Liang [Ames Laboratory; Anderson, Iver [Ames Laboratory; Riedemann, Trevor [Ames Laboratory; Russell, Alan [Ames Laboratory

    2014-09-01

    Deformation processed metal–metal (matrix–reinforcement) composites (DMMCs) are high-strength, high-conductivity in situ composites produced by severe plastic deformation. The electrical resistivity of DMMCs is rarely investigated mechanistically and tends to be slightly higher than the rule-of-mixtures prediction. In this paper, we analyze several possible physical mechanisms (i.e. phonons, interfaces, mutual solution, grain boundaries, dislocations) responsible for the electrical resistivity of DMMC systems and how these mechanisms could be affected by processing conditions (i.e. temperature, deformation processing). As an innovation, we identified and assembled the major scattering mechanisms for specific DMMC systems and modeled their electrical resistivity in combination. From this analysis, it appears that filament coarsening rather than dislocation annihilation is primarily responsible for the resistivity drop observed in these materials after annealing and that grain boundary scattering contributes to the resistivity at least at the same magnitude as does interface scattering.

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

    SciTech Connect

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

    1986-11-01

    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).

  20. Association of Multiple-Antibiotic-Resistance Profiles with Point and Nonpoint Sources of Escherichia coli in Apalachicola Bay

    Microsoft Academic Search

    SALINA PARVEEN; RENDI L. MURPHREE; LEE EDMISTON; CHARLES W. KASPAR; KENNETH M. PORTIER; MARK L. TAMPLIN

    1997-01-01

    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 deter- mined 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

  1. An electrically modifiable synapse array of resistive switching memory

    Microsoft Academic Search

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

    2009-01-01

    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

  2. Comparative Genomics of Klebsiella pneumoniae Strains with Different Antibiotic Resistance Profiles?†

    PubMed Central

    Kumar, Vinod; Sun, Peng; Vamathevan, Jessica; Li, Yong; Ingraham, Karen; Palmer, Leslie; Huang, Jianzhong; Brown, James R.

    2011-01-01

    There is a global emergence of multidrug-resistant (MDR) strains of Klebsiella pneumoniae, a Gram-negative enteric bacterium that causes nosocomial and urinary tract infections. While the epidemiology of K. pneumoniae strains and occurrences of specific antibiotic resistance genes, such as plasmid-borne extended-spectrum ?-lactamases (ESBLs), have been extensively studied, only four complete genomes of K. pneumoniae are available. To better understand the multidrug resistance factors in K. pneumoniae, we determined by pyrosequencing the nearly complete genome DNA sequences of two strains with disparate antibiotic resistance profiles, broadly drug-susceptible strain JH1 and strain 1162281, which is resistant to multiple clinically used antibiotics, including extended-spectrum ?-lactams, fluoroquinolones, aminoglycosides, trimethoprim, and sulfamethoxazoles. Comparative genomic analysis of JH1, 1162281, and other published K. pneumoniae genomes revealed a core set of 3,631 conserved orthologous proteins, which were used for reconstruction of whole-genome phylogenetic trees. The close evolutionary relationship between JH1 and 1162281 relative to other K. pneumoniae strains suggests that a large component of the genetic and phenotypic diversity of clinical isolates is due to horizontal gene transfer. Using curated lists of over 400 antibiotic resistance genes, we identified all of the elements that differentiated the antibiotic profile of MDR strain 1162281 from that of susceptible strain JH1, such as the presence of additional efflux pumps, ESBLs, and multiple mechanisms of fluoroquinolone resistance. Our study adds new and significant DNA sequence data on K. pneumoniae strains and demonstrates the value of whole-genome sequencing in characterizing multidrug resistance in clinical isolates. PMID:21746949

  3. Electrical resistivity behavior of substituted perovskite manganates sintered at different temperatures

    SciTech Connect

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

    1999-12-01

    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.

  4. An Ultra-Precise System for Electrical Resistivity Tomography Measurements

    SciTech Connect

    LaBrecque, Douglas J; Adkins, Paula L

    2008-12-09

    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

  5. Changing antimicrobial resistance profiles among Neisseria gonorrhoeae isolates in Italy, 2003 to 2012.

    PubMed

    Carannante, Anna; Renna, Giovanna; Dal Conte, Ivano; Ghisetti, Valeria; Matteelli, Alberto; Prignano, Grazia; Impara, Giampaolo; Cusini, Marco; D'Antuono, Antonietta; Vocale, Caterina; Antonetti, Raffaele; Gaino, Marina; Busetti, Marina; Latino, Maria Agnese; Mencacci, Antonella; Bonanno, Carmen; Cava, Maria Carmela; Giraldi, Cristina; Stefanelli, Paola

    2014-10-01

    The emergence of Neisseria gonorrhoeae isolates displaying resistance to antimicrobial agents is a major public health concern and a serious issue related to the occurrence of further untreatable gonorrhea infections. A retrospective analysis on 1,430 N. gonorrhoeae isolates, collected from 2003 through 2012, for antimicrobial susceptibility by Etest and molecular characterization by Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) was carried out in Italy. Azithromycin-resistant gonococci decreased from 14% in 2007 to 2.2% in 2012. Similarly, isolates with high MICs to cefixime (>0.125 mg/liter) decreased from 11% in 2008 to 3.3% in 2012. The ciprofloxacin resistance rate remains quite stable, following an increasing trend up to 64% in 2012. The percentage of penicillinase-producing N. gonorrhoeae (PPNG) significantly declined from 77% in 2003 to 7% in 2012. A total of 81 multidrug-resistant (MDR) gonococci were identified, showing 11 different antimicrobial resistance patterns. These were isolated from men who have sex with men (MSM) and from heterosexual patients. Two sequence types (STs), ST661 and ST1407, were the most common. Genogroup 1407, which included cefixime-, ciprofloxacin-, and azithromycin-resistant isolates, was found. In conclusion, a change in the antimicrobial resistance profiles among gonococci was identified in Italy together with a percentage of MDR isolates. PMID:25070110

  6. Electric field polarization around Ioannina VAN station, Greece, inferred from a resistivity mapping

    NASA Astrophysics Data System (ADS)

    Kanda, Wataru; Uyeshima, Makoto; Makris, John; Orihara, Yoshiaki; Hase, Hideaki; Nagao, Toshiyasu; Uyeda, Seiya

    2000-05-01

    In the summer of 1997, we made a bipole-dipole mapping survey around Ioannina station of VAN (Varotsos, Alexopoulos, and Nomicos), where detection of the pre-seismic electric signal (SES) has been repeatedly reported. Since we had found the characteristic directional properties of the electric field in the previous study, the present study was aimed to examine it by investigating the shallow electric structure around the station. The apparent resistivity tensor was derived from two sets of measured voltages at each receiver position. From a rough sketch of the resistivity tensor distribution, we found that the electric field was enhanced along the direction parallel to the trend of the basin at receivers located in the conductive basin, and perpendicular to it at receivers in the resistive mountainside. Conductance distribution models with thin plates were constructed by using the measured voltages. The results showed that the VAN station is located on the resistive portion near the contact between the conductive and the resistive part. Furthermore, we simulated the apparent resistivity tensor near the VAN station on the inferred conductance distribution model. Although the directional property similar to those of magnetotelluric (MT) and lightning electric field was not reproduced there, we found that the electric field polarization is affected by heterogeneous structure not only around receivers but also around the source.

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

    PubMed Central

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

    2010-01-01

    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. PMID:20363862

  8. Fracture network characterisation of a landslide by electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Szalai, S.; Szokoli, K.; Novák, A.; Tóth, Á.; Metwaly, M.; Prácser, E.

    2014-06-01

    In contrary to most of the landslide studies which concentrate to the sliding surface in this paper the fracture system of a loess landslide is investigated. The continuity and geometry, orientation and dip of the major fractures are crucial parameters for assessing rock stability and landslide evolution. Rain infiltrating moreover easily into the rock mass through fractures providing lubrication for the material to slide, and increases the self-mass of the material increasing the slumping rate. Fracture maps enable beside of the characterisation of the fractured area the delineation of the endangered area of slow-moving landslides in due time and getting information about its inner structure. For constructing such maps Electrical Resistivity Tomography (ERT) measurements have been carried out using different geoelectric configurations. In spite of the high density of the fractures and their changing physical parameters in function of their water content - which make the interpretation rather difficult - a number of fractures have been detected and more or less well localised. On the basis of the present research the application of the Schlumberger and the Pole-Dipole arrays is recommended to fulfil the aim of the study. The optimised Stummer array is at the same time the only array which presents conductive anomalies (supposedly water filled fractures), as well, and indicates that fractures elongate deep downwards. Because these features seem to be realistic based on field observations or theoretical considerations the Stummer array may be a very good tool for completing e.g. P-Dp measurements. The study area could have been divided by all arrays into differently fractured zones, which assists a lot in understanding the landslide structure and evolution. It was shown, moreover, that in the still passive area there are thick fractures, too, verifying its dangerousness, as well. The ERT results enabled localising the rupture surfaces of future slumps which proved to be distributed uniformly with about 10 m distance between them and predicting mass movements which may prevent the slump along the visible fracture. Similar unidirectional fracture systems could be investigated by the ERT method for any hydrogeological or engineering geological aim.

  9. The Quantum Hall Eect as an Electrical Resistance Standard

    Microsoft Academic Search

    B. Jeckelmann; B. Jeanneret

    2004-01-01

    The quantum Hall eect (QHE) provides an invariant reference for resistance linked to natural constants. It is used worldwide to maintain and compare the unit of resistance. The reproducibility reached today is almost two orders of magnitude better than the uncertainty of the determination of the ohm in the International System of Units SI. This article is a summary of

  10. Thermal history of carbon-ber polymer-matrix composite, evaluated by electrical resistance measurement

    E-print Network

    Chung, Deborah D.L.

    ; accepted 9 October 2000 Abstract The thermal history of carbon-®ber nylon-6 matrix composite was evaluatedThermal history of carbon-®ber polymer-matrix composite, evaluated by electrical resistance by the degree of crystallinity and the thermal oxidative degradation. The resistance results were consistent

  11. Strain-dependent electrical resistance of tin-doped indium oxide on polymer substrates

    E-print Network

    Cairns, Darran

    Strain-dependent electrical resistance of tin-doped indium oxide on polymer substrates Darran R 12 January 2000 The increase in sheet resistance of indium­tin­oxide ITO films on polyethylene on an electromechanical study of the performance of tin-doped indium oxide coated PET. A surprising result was uncovered

  12. Transient mechanical and electrical properties of uncooled resistive microbolometer focal plane arrays

    Microsoft Academic Search

    Biao Li; Shusen Huang; Xin Zhang

    2004-01-01

    Recent advances in MEMS and focal plane array (FPA) technologies have led to the development of manufacturing microbolometers monolithically on a readout integrated circuit (ROIC). In this work, both numerical and finite element methods were performed to simulate the transient electrical and mechanical responses of resistive microbolometer FPAs made by several TCR (thermal coefficient of resistance) materials including a-Si, VOx

  13. Effect of pressure on the electrical resistivity of water-saturated crystalline rocks

    Microsoft Academic Search

    W. F. Brace; A. S. Orange; T. R. Madden

    1965-01-01

    Electrical r.esistivity of eight igneous rocks and two crystalline limestones was measured at pressures to 10 kb. The rocks were saturated with tap water or salt solution, and the pore pressure was maintained near zero. The dependence of resistivity on temperature, porosity, and pore fluid salinity suggested that conduction was primarily electrolytic through- out the .entire pressure range, even though

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

    Microsoft Academic Search

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

    2006-01-01

    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

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

    Microsoft Academic Search

    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

    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

  16. Generated on 04/07/13 by the Office of Institutional Research and Planning. Doctoral Program Profile: Electrical Engineering

    E-print Network

    Profile: Electrical Engineering This program is part of the Department of Electrical Engineering://www.eecs.ku.edu/prospective_students/graduate Notes: Faculty data include all faculty in the Department of Electrical Engineering and Computer Science. Department Faculty: Electrical Engineering and Computer Science Fall 2012 Total Faculty 34 Tenured and Tenure

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

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

    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.

  18. Effect of contact statistics on electrical contact resistance Yong Hoon Janga)

    E-print Network

    Barber, James R.

    Effect of contact statistics on electrical contact resistance Yong Hoon Janga) School of Mechanical; accepted 10 September 2003 The flow of electrical current through a microscopic actual contact spot between two conductors is influenced by the flow through adjacent contact spots. A smoothed version

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

    SciTech Connect

    Desbrandes, R.

    1983-10-25

    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.

  20. Silicone oil contamination and electrical contact resistance degradation of low-force gold contacts.

    SciTech Connect

    Dugger, Michael Thomas; Dickrell, Daniel John, III

    2006-02-01

    Hot-switched low-force gold electrical contact testing was performed using a nanomechanical test apparatus to ascertain the sensitivity of simulated microelectromechanical systems (MEMS) contact to silicone oil contamination. The observed cyclic contact resistance degradation was dependent on both closure rate and noncontact applied voltage. The decomposition of silicone oil from electrical arcing was hypothesized as the degradation mechanism.

  1. Application of electrical resistance tomography to detect deposition in hydraulic conveying systems

    Microsoft Academic Search

    Y. S. Fangary; R. A. Williams; W. A. Neil; J. Bond; I. Faulks

    1998-01-01

    The use of electrical resistance tomography to monitor the extent of solids deposited during slurry conveying in a horizontal pipe is demonstrated. The method involves placing 16 electrodes around the inner bore of the pipe section, from which a two-dimensional electrical conductivity map within the cross-section can be deduced. The sensitivity of the method is quantified for static and flowing

  2. Collisional theory of electrical resistivity in trapped electron regimes. Memorandum report

    Microsoft Academic Search

    B. H. Hui; N. Winsor; B. Coppi

    1976-01-01

    The distribution function is determined numerically for electrons subject to magnetic trapping, electron-electron and electron-ion collisions, and an electric field large enough to invalidate the Spitzer-Harm (classical) approximation. The electrical resistivity is determined and compared with analytical theory for Tokamaks.

  3. In situ measurement of electrical resistivity of marine sediments, results from Cascadia Basin off Vancouver Island

    Microsoft Academic Search

    Daniela Jansen; Bernd Heesemann; Marion Pfender; Andreas Rosenberger; Heinrich Villinger

    2005-01-01

    Electrical properties of sediments encompass information about other linked physical properties, such as porosity and thermal conductivity. In situ measurements of electrical resistivity offer a cost- and time effective method for obtaining a comprehensive overview of near surface sediment physical properties. They also provide a quality check for in situ measurements of related sediment properties or for data obtained from

  4. An efficient, low profile, electrically small, three-dimensional, very high frequency magnetic EZ antenna

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Ching; Ziolkowski, Richard W.; Nielsen, Jean A.; Tanielian, Minas H.; Holloway, Christopher L.

    2010-03-01

    A very high frequency version of the electrically small, coax-fed, three-dimensional magnetic EZ antenna was designed and tested. The fabricated antenna was formed by integrating a capacitively loaded loop element with a coaxially-fed, electrically small, semicircular loop antenna. This low profile antenna (height ˜?/25) had an electrical size that was ka ˜0.46 at 105.2 MHz (where a is the radius of the minimum enclosing hemisphere). Nearly complete matching to the 50 ? source and a high overall efficiency (nearly 95%) were achieved. The numerically predicted and the measured results were in good agreement.

  5. Evaluation of antimicrobial resistance profiles of Salmonella isolates from broiler chickens at slaughter in Alberta, Canada.

    PubMed

    Mainali, C; McFall, M; King, R; Irwin, R

    2014-03-01

    Antimicrobial-resistant Salmonella species are threatening to become a serious public health problem. Therefore, surveillance and prudent use of antimicrobials is needed in both the agricultural and human health sectors. The aim of this study was to describe the antimicrobial susceptibility profiles of Salmonella isolates recovered from healthy broiler chickens at slaughter from November 2004 to April 2005. Salmonella isolates recovered from 36 broiler flocks in Alberta, Canada, were serotyped and tested for antimicrobial susceptibility against 15 antimicrobials. Of 272 Salmonella isolates tested, 64.0% were resistant to one or more antimicrobials, 10.0% were resistant to three or more antimicrobials, and 1.8% were resistant to five antimicrobials. All isolates were susceptible to amikacin, amoxicillin-clavulanic acid, ceftiofur, cefoxitin, ceftriaxone, ciprofloxacin, and nalidixic acid. The highest prevalence of resistance was to tetracycline (54.8%), followed by streptomycin (24.2%) and sulfisoxazole (8.4%). The most common multiantimicrobial resistance patterns were to streptomycin-tetracycline (24.3%), streptomycin-sulfisoxazole-tetracycline (6.6%), and ampicillin-streptomycin-sulfisoxazole-tetracycline (3.7%). The strongest associations were observed between resistance to kanamycin and tetracycline (odds ratio = 65.7, P = 0.001) and to ampicillin and sulfisoxazole (odds ratio = 62.9, P = 0.001). Salmonella Hadar and Salmonella Heidelberg were the two most common serovars accounting for 40.4 and 13.6% of the total isolates, respectively. Eighty-one percent and 12.7% of Salmonella Hadar isolates and 62.0 and 8.1% of Salmonella Heidelberg isolates were resistant to 1 or more and three or more antimicrobials, respectively. The flock level prevalence of resistance ranged from 5.6% for trimethoprim-sulfamethoxazole to 83.3% for tetracycline. This study provides baseline information on antimicrobial susceptibility of Salmonella isolates of broiler chickens at slaughter in Alberta that can serve as a benchmark for future research. PMID:24674442

  6. Percolation of gallium dominates the electrical resistance of focused ion beam deposited metals

    SciTech Connect

    Faraby, H. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); DiBattista, M. [Qualcomm Technologies Incorporated, San Diego, California 92121 (United States); Bandaru, P. R., E-mail: pbandaru@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2014-04-28

    Metal deposition through focused ion beam (FIB) based systems is thought to result in material composed of the primary metal from the metallo-organic precursor in addition to carbon, oxygen, and gallium. We determined, through electrical resistance and chemical composition measurements on a wide range of FIB deposited platinum and tungsten lines, that the gallium ion (Ga{sup +}) concentration in the metal lines plays the dominant role in controlling the electrical resistivity. Effective medium theory, based on McLachlan's formalisms, was used to describe the relationship between the Ga{sup +} concentration and the corresponding resistivity.

  7. Electrical Resistance of Ceramic Matrix Composites for Damage Detection and Life-Prediction

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Morscher, Gregory N.; Xia, Zhenhai

    2008-01-01

    The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection or inspection of a component during "down time". The correlation of damage with appropriate failure mechanism can then be applied to accurate life prediction for high-temperature ceramic matrix composites.

  8. 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...

  9. An Equivalent Lumped Circuit Model for Thin Avalanche Photodiodes With Nonuniform Electric Field Profile

    Microsoft Academic Search

    Mohsen Jalali; Mohammad K. Moravvej-Farshi; Saeid Masudy-Panah; Abdolreza Nabavi

    2010-01-01

    A staircase approximation method is deployed to model nonuniform field in the multiplication region and its surrounding ambient of a thin avalanche photodiode (APD). To the best of our knowledge, this is the first instance of introducing an equivalent circuit model that is taking the effect of the electric field profile in a thin APD's multiplication region and its surroundings

  10. Electrical resistivity tomography at the search of groundwater near Anapa town in the south of Russia.

    NASA Astrophysics Data System (ADS)

    Kvon, Dina; Vladimir, Shevnin; Boris, Nikulin; Albert, Ryjov; Alexey, Skobelev

    2013-04-01

    Electrical resistivity tomography at the search of groundwater near Anapa town in the south of Russia. Kvon D. A.(1)*, Shevnin V.A.(1), Nikulin B. A.(1), Ryjov A. A.(2), Skobelev A. O.(1) (1)Geophysical dept., Faculty of Geology, Moscow state university; (2)VSEGINGEO Due to acute shortage of fresh drinking water near Anapa town (not far from the Black Sea), geophysical investigations were performed for searching and mapping aquifers in the area, where, according to rare wells exist probability to find fresh underground water. Geophysical explorations were carried out by Electrical resistivity tomography (ERT) method and water resistivity measurements. The resistivity of fresh groundwater is 15 Ohm.m, its salinity is 0.4 g/l. The structure of the area has been obtained by previous geological and hydrogeological studies and boreholes drilling. Geological structure of the area consists of two parts: the upper part of cross-section presented by loose lacustrine-alluvial sediments of Upper Pleistocene - Holocene, the lower part presented by hard rocs of carbonate-flysch formation of Upper Cretaceous age consisted of marl and limestone. Prospective areas to find underground water are: water-bearing horizon of upper Pleistocene-Holocene sediments, which is presented by gravel layer (base layer of modern lacustrine-alluvial sediments), and fractured zones in hard rocks of the carbonate-flysch formation of Maastricht age (Supseh formation). Analysis of rocks' resistivity obtained from Electrical resistivity tomography followed by calculation of rock resistivity on known petrophysical parameters (in Petrowin program created by A. A. Ryjov) [Shevnin et al., 2007]. The calculation showed that there is low clay content in carbonate rocks of the studied area, and the rock is limestone, not marl. Measurement of rock samples with X-ray radiometric method showed high calcium content (30-35%) or 75-87.5% limestone. This fact shows that flysch formation of the area is mainly carbonate, which is fit to results of petrophysical modeling with Petrowin program, which calculated rock resistivity from porosity and clay content. On the base of Electrical resistivity tomography results, calculated rocks' resistivity and drilling data, table of rocks' resistivity was created and resistivity intervals promising to search for underground water were determined. Electric resistivity of rocks in cross-section according to histogram obtained on Electrical resistivity tomography data varies from 20 to 600 Ohm.m and clear divides into two sections: 20-100 Ohm.m for loose sediments and 70-600 Ohm.m for hard rocks. On geoelectrical resistivity sections, which were obtained from Electrical resistivity tomography inversion, we draw isolines of boundary values for resistivity (50-100 Ohm.m for sandy-gravel layer, 100-150 Ohm.m for fractured carbonate-flysch), which detached promising areas to search for underground water taking with account aquifers position according to wells. As a result the Electrical resistivity tomography method succeeded to search groundwater and to determine aquifers position. We pointed out several areas for subsequent drilling found with Electrical resistivity tomography, and we are waiting confirmation of underground water findings. Reference Shevnin V., Mousatov A., Ryjov A. and Delgado-Rodriquez O. Estimation of clay content in soil based on resistivity modeling and laboratory measurements. Geophysical Prospecting, 2007, 55, p.265-275

  11. Genetic Profiles of Fluoroquinolone-Nonsusceptible Klebsiella pneumoniae Among Cephalosporin-Resistant K. pneumoniae.

    PubMed

    Nagasaka, Yukiko; Kimura, Kouji; Yamada, Keiko; Wachino, Jun-Ichi; Jin, Wanchun; Notake, Shigeyuki; Yanagisawa, Hideji; Arakawa, Yoshichika

    2015-04-01

    The rate of fluoroquinolone (FQ) resistance among the cephalosporin-resistant Klebsiella pneumoniae is considerably high, however, their genetic profiles have not been well investigated. We selected 61 ciprofloxacin-nonsusceptible isolates from 102 K. pneumoniae isolates judged to be "resistant" to some cephalosporins during 2009 and 2012 throughout Japan. Pulsed-field gel electrophoresis excluded clonal isolates, and 29 isolates were subjected to multilocus sequence typing (MLST), detection of the amino acid substitutions in the quinolone resistance determining regions (QRDRs) of GyrA and ParC, ?-lactamase typing, and identification of plasmid-mediated quinolone resistance (PMQR) genes. PCR-based replicon typing was performed, after PMQR gene transfer. Four major sequence types (STs) or clonal complexes (CCs), that is, ST37, CC17 (consisting of ST17 and ST20), ST11, and CC528 (consisting of ST528 and ST1130), were found, and they accounted for 48.2% of the isolates tested. Amino acid substitutions in the QRDRs and the presence of PMQR genes were identified in 20 (68.9%) and 18 (62.0%) isolates, respectively. The replicon type of three PMQR-carrying plasmids was IncN, but others were nontypable. Fifteen (83.3%) of the 18 PMQR-harboring isolates coharbored blaCTX-M and/or blaDHA-1. Ciprofloxacin-nonsusceptible K. pneumoniae clinical isolates demonstrating cephalosporin resistance often belong to the global epidemic lineages and possess PMQR and/or QRDR substitutions. PMID:25419619

  12. Electrical resistance of CNT-PEEK composites under compression at different temperatures

    PubMed Central

    2011-01-01

    Electrically conductive polymers reinforced with carbon nanotubes (CNTs) have generated a great deal of scientific and industrial interest in the last few years. Advanced thermoplastic composites made of three different weight percentages (8%, 9%, and 10%) of multiwalled CNTs and polyether ether ketone (PEEK) were prepared by shear mixing process. The temperature- and pressure-dependent electrical resistance of these CNT-PEEK composites have been studied and presented in this paper. It has been found that electrical resistance decreases significantly with the application of heat and pressure. PMID:21711952

  13. Resistance and internal electric field in cloud-to-ground lightning channel

    NASA Astrophysics Data System (ADS)

    Cen, Jianyong; Yuan, Ping; Xue, Simin; Wang, Xuejuan

    2015-02-01

    Cloud-to-ground lightning with six return strokes has been recorded by slitless spectrograph and the system of fast antenna and slow antenna. The physical parameters of the discharge channel have been obtained based on the combination of spectra and synchronous radiated electric field. The resistance and internal electric field of the channel are studied as the focus in this paper. The results show that the resistances per unit length of the lightning channel are in the order of 10-2-10-1 ?/m and the internal electric field strengths are in the order of 103 V/m.

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

    SciTech Connect

    Youngblood, Gerald E.; Thomsen, Edwin C.; Henager, Charles H.

    2013-06-30

    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%.

  15. Cross-section electrical resistance tomography of La Soufrière of Guadeloupe lava dome

    NASA Astrophysics Data System (ADS)

    Lesparre, Nolwenn; Grychtol, Bart?omiej; Gibert, Dominique; Komorowski, Jean-Christophe; Adler, Andy

    2014-06-01

    The electrical resistivity distribution at the base of La Soufrière of Guadeloupe lava dome is reconstructed by using transmission electrical resistivity data obtained by injecting an electrical current between two electrodes located on opposite sides of the volcano. Several pairs of injection electrodes are used in order to constitute a data set spanning the whole range of azimuths, and the electrical potential is measured along a cable covering an angular sector of ?120° along the basis of the dome. The data are inverted to perform a slice electrical resistivity tomography (SERT) with specific functions implemented in the EIDORS open source package dedicated to electrical impedance tomography applied to medicine and geophysics. The resulting image shows the presence of highly conductive regions separated by resistive ridges. The conductive regions correspond to unconsolidated material saturated by hydrothermal fluids. Two of them are associated with partial flank collapses and may represent large reservoirs that could have played an important role during past eruptive events. The resistive ridges may represent massive andesite and are expected to constitute hydraulic barriers.

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

    PubMed Central

    1995-01-01

    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. PMID:8576703

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

    SciTech Connect

    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

    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.

  18. Comparative metabolite profiling of Solanum tuberosum against six wild Solanum species with Colorado potato beetle resistance.

    PubMed

    Tai, Helen H; Worrall, Kraig; Pelletier, Yvan; De Koeyer, David; Calhoun, Larry A

    2014-09-10

    The Colorado potato beetle Leptinotarsa decemlineata (Say) (CPB) is a coleopteran herbivore that feeds on the foliage on Solanum species, in particular, potato. Six resistant wild Solanum species were identified, and two of these species had low levels of glycoalkaloids. Comparative analysis of the untargeted metabolite profiles of the foliage using UPLC-qTOF-MS was done to find metabolites shared between the wild species but not with Solanum tuberosum (L.) to identify resistance-related metabolites. It was found that only S. tuberosum produced the triose glycoalkaloids solanine and chaconine. Instead, the six wild species produced glycoalkaloids that shared in common tetrose sugar side chains. Additionally, there were non-glycoalkaloid metabolites associated with resistance including hydroxycoumarin and a phenylpropanoid, which were produced in all wild species but not in S. tuberosum. PMID:25144460

  19. The variation of electrical resistance of near stoichiometric NiTi during thermo-mechanic procedures

    NASA Astrophysics Data System (ADS)

    Wu, X. D.; Wu, J. S.; Wang, Z.

    1999-10-01

    The variation of electrical resistance of near stoichiometric NiTi during some thermo-mechanic procedures was studied in this paper. The results show that when the R-phase does not exist in the near stoichiometric NiTi wire, the electrical resistance of NiTi wire increases linearly with the increase of strain at constant temperature. When a phase transformation or martensite reorientation takes place, the slopes of the electrical against strain curves are changed. During the cycles of tensile loading and unloading, electrical resistance of NiTi wire increases as the increase of the cycle numbers, but will stabilize after approximately 15 cycles. Furthermore, the possibility to use NiTi wire as a sensor in the intelligent materials system is discussed.

  20. Electrical resistivity response of amorphous carbon nitride thin films in various gas atmospheres

    NASA Astrophysics Data System (ADS)

    Tamura, Naoyuki; Aono, Masami; Abe, Hiroshi; Kitazawa, Nobuaki; Watanabe, Yoshihisa

    2015-04-01

    Electrical behaviors of amorphous carbon nitride (a-CNx) films following exposure to various gas species were investigated. The a-CNx film was prepared by reactive RF magnetron sputtering at 873 K. The resistivity of the film was measured in flowing He, N2, O2, Ar, and CO2. Regardless of gas species, the electrical resistivity of the a-CNx film dropped rapidly following gas injection and recovered in the evacuation process. This phenomenon is closely related to the changes in the film microstructure and electrical state. The response time in the adsorption process decreased with increasing gas pressure. The variation range of the electrical resistivity changed depending on the gas species.

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

    DOEpatents

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

    1997-01-01

    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.

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

    DOEpatents

    Daily, W.D.; Laine, D.L.; Laine, E.F.

    1997-08-26

    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. 6 figs.

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

    DOEpatents

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

    2001-01-01

    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.

  4. Identifying the changes of geo-engineering properties of dunites due to weathering utilizing electrical resistivity tomography (ERT)

    NASA Astrophysics Data System (ADS)

    Ündül, Ömer; Tu?rul, Atiye; Özyal?n, ?enol; Halil Zarif, ?.

    2015-04-01

    Weathering phenomena have an important role in many construction facilities with varying depths and grades. Due to the anisotropic and heterogeneous nature of weathering profiles of some rocks, uncertainities exist in determining the geo-engineering properties. Geo-electrical studies have been utilized to overcome such uncertainities for various subsurface conditions including the determination of boundaries between weathered and unweathered parts of different rock types. In this study, the electrical resistivity tomography (ERT) results were correlated with conventional methods in determining the effects of weathering on the geo-engineering properties of dunites. During the research, weathering grades were determined by field studies including discontinuity spacings, aperture and properties of fill materials. The detailed petrographical studies, determination of petrophysical properties (e.g. water absorption and effective porosity) and mechanical properties (e.g. unconfined compressive strength (UCS)) constitute the laboratory studies. ERT studies were carried out in a row of sixty electrodes with electrode spacings of 0.5?m utilizing a Wenner–Schlumberger configuration. According to the comparison of the inversion model sections with the weathering profiles obtained by field and laboratory studies it is concluded that the use of ERT with a Wenner–Schlumberger configuration supplies comparable data for wider subsurface areas from the view of weathering and its effect on geo-engineering properties of dunites. In addition, ERT techniques are very useful where conventional techniques are inadequate in determining the full weathering profile.

  5. Model 'zero-age' lunar thermal profiles resulting from electrical induction

    NASA Technical Reports Server (NTRS)

    Herbert, F.; Sonett, C. P.; Wiskerchen, M. J.

    1977-01-01

    Thermal profiles for the moon are calculated under the assumption that a pre-main-sequence T-Tauri-like solar wind excites both transverse magnetic and transverse electric induction while the moon is accreting. A substantial initial temperature rise occurs, possibly of sufficient magnitude to cause subsequent early extensive melting throughout the moon in conjunction with nominal long-lived radioactives. In these models, accretion is an unimportant direct source of thermal energy but is important because even small temperature rises from accretion cause significant changes in bulk electrical conductivity. Induction depends upon the radius of the moon, which we take to be accumulating while it is being heated electrically. The 'zero-age' profiles calculated in this paper are proposed as initial conditions for long-term thermal evolution of the moon.

  6. Identification of transcription factors potential related to brown planthopper resistance in rice via microarray expression profiling

    PubMed Central

    2012-01-01

    Background Brown planthopper (BPH), Nilaparvata lugens Stål, is one of the most destructive insect pests of rice. The molecular responses of plants to sucking insects resemble responses to pathogen infection. However, the molecular mechanism of BPH-resistance in rice remains unclear. Transcription factors (TF) are up-stream regulators of various genes that bind to specific DNA sequences, thereby controlling the transcription from DNA to mRNA. They are key regulators for transcriptional expression in biological processes, and are probably involved in the BPH-induced pathways in resistant rice varieties. Results We conducted a microarray experiment to analyze TF genes related to BPH resistance in a Sri Lankan rice cultivar, Rathu Heenati (RHT). We compared the expression profiles of TF genes in RHT with those of the susceptible rice cultivar Taichun Native 1 (TN1). We detected 2038 TF genes showing differential expression signals between the two rice varieties. Of these, 442 TF genes were probably related to BPH-induced resistance in RHT and TN1, and 229 may be related to constitutive resistance only in RHT. These genes showed a fold change (FC) of more than 2.0 (P<0.05). Among the 442 TF genes related to BPH-induced resistance, most of them were readily induced in TN1 than in RHT by BPH feeding, for instance, 154 TF genes were up-regulated in TN1, but only 31 TF genes were up-regulated in RHT at 24 hours after BPH infestation; 2–4 times more TF genes were induced in TN1 than in RHT by BPH. At an FC threshold of >10, there were 37 induced TF genes and 26 constitutive resistance TF genes. Of these, 13 were probably involved in BPH-induced resistance, and 8 in constitutive resistance to BPH in RHT. Conclusions We explored the molecular mechanism of resistance to BPH in rice by comparing expressions of TF genes between RHT and TN1. We speculate that the level of gene repression, especially for early TF genes, plays an important role in the defense response. The fundamental point of the resistance strategy is that plants protect themselves by reducing their metabolic level to inhibit feeding by BPH and prevent damage from water and nutrient loss. We have selected 21 TF genes related to BPH resistance for further analyses to understand the molecular responses to BPH feeding in rice. PMID:23228240

  7. ELECTRICAL RESISTIVITY TECHNIQUE TO ASSESS THE INTEGRITY OF GEOMEMBRANE LINERS

    EPA Science Inventory

    Two-dimensional electrical modeling of a liner system was performed using computer techniques. The modeling effort examined the voltage distributions in cross sections of lined facilities with different leak locations. Results confirmed that leaks in the liner influenced voltage ...

  8. Electrical resistivity tomography as monitoring tool for unsaturated zone transport: an example of preferential transport of deicing chemicals.

    PubMed

    Wehrer, Markus; Lissner, Heidi; Bloem, Esther; French, Helen; Totsche, Kai Uwe

    2014-08-01

    Non-invasive spatially resolved monitoring techniques may hold the key to observe heterogeneous flow and transport behavior of contaminants in soils. In this study, time-lapse electrical resistivity tomography (ERT) was employed during an infiltration experiment with deicing chemical in a small field lysimeter. Deicing chemicals like potassium formate, which frequently impact soils on airport sites, were infiltrated during snow melt. Chemical composition of seepage water and the electrical response was recorded over the spring period 2010. Time-lapse electrical resistivity tomographs are able to show the infiltration of the melt water loaded with ionic constituents of deicing chemicals and their degradation product hydrogen carbonate. The tomographs indicate early breakthrough behavior in parts of the profile. Groundtruthing with pore fluid conductivity and water content variations shows disagreement between expected and observed bulk conductivity. This was attributed to the different sampling volume of traditional methods and ERT due to a considerable fraction of immobile water in the soil. The results show that ERT can be used as a soil monitoring tool on airport sites if assisted by common soil monitoring techniques. PMID:24194415

  9. Electrical resistivity cross-section across the Garhwal Himalaya: Proxy to fluid-seismicity linkage

    NASA Astrophysics Data System (ADS)

    Rawat, Gautam; Arora, B. R.; Gupta, P. K.

    2014-12-01

    Magnetotelluric (MT) measurements along a profile cutting across the Garhwal Himalaya of India are inverted to obtain 2-D electrical resistivity structures of the Himalayan wedge and of the underthrusting Indian plate. The imaged resistivity cross-section is dominated by a low-angle north-east dipping intra-crustal high conducting layer (IC-HCL) with an average thickness of 5 km. At transition from the Lesser Himalaya to the Higher Himalaya, the IC-HCL is marked by a ramp structure across which its top jumps from a depth of 8 km to 13 km. High conductivity of the layer is caused by pounding of upward propagating metamorphic fluids trapped by tectonically induced neutral buoyancy. In compression regime of the Himalaya, the mechanical weakening effects of the fluids counteract the fault-normal stresses, thereby facilitating thrust-type earthquakes on a plane imaged as the top of the IC-HCL. It is suggested that in the Himalaya collision belt, like the active subduction zone, the active seismic plane forming seat of large and great earthquakes is located a few kilometers above the top of the down-going plate. In this tectonic setting, the high conductance ramp symbolizes a block of low shear strength and high strain, which under the deviatoric stresses release accentuated stresses into the brittle crust, thereby generating small but more frequent earthquakes in the narrow Himalayan Seismic Belt. In response to either the co-seismic pumping or the stress transfer during inter-seismic period, the upward infiltration of fluid fluxes into the over pressurized zones sufficiently reduces the shear strength of local thrusts and shear zones, turning these into locales of concentrated seismicity.

  10. Simultaneous electrical resistivity and mass uptake measurements in bromine intercalated fibers

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.

    1986-01-01

    Changes in mass and electrical resistivity of several types of pitch-based and vapor-grown graphite fibers were monitored during reaction with bromine. The observed threshold pressure dependent reaction suggested that the fibers were intercalated. In the fully brominated compound, the mass was increased by 44 percent and the resistivity was improved by a factor of 17. In the residue compound, the mass was increased by 22 percent and the resistivity was improved by a factor of 5. Fibers possessing different degrees of graphitization had surprisingly similar changes in both mass and resistivity.

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

    Microsoft Academic Search

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

    2008-01-01

    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

  12. The combined effect of electrical stimulation and resistance isometric contraction on muscle atrophy in rat tibialis anterior muscle

    PubMed Central

    Fujita, Naoto; Murakami, Shinichiro; Arakawa, Takamitsu; Miki, Akinori; Fujino, Hidemi

    2011-01-01

    Electrical stimulation has been used to prevent muscle atrophy, but this method is different in many previous studies, appropriate stimulation protocol is still not decided. Although resistance exercise has also been shown to be an effective countermeasure on muscle atrophy, almost previous studies carried out an electrical stimulation without resistance. It was hypothesized that electrical stimulation without resistance is insufficient to contract skeletal muscle forcefully, and the combination of electrical stimulation and forceful resistance contraction is more effective than electrical stimulation without resistance to attenuate muscle atrophy. This study investigated the combined effects of electrical stimulation and resistance isometric contraction on muscle atrophy in the rat tibialis anterior muscle. The animals were divided into control, hindlimb unloading (HU), hindlimb unloading plus electrical stimulation (ES), and hindlimb unloading plus the combination of electrical stimulation and resistance isometric contraction (ES+IC). Electrical stimulation was applied to the tibialis anterior muscle percutaneously for total 240 sec per day. In the ES+IC group, the ankle joint was fixed to produce resistance isometric contraction during electrical stimulation. After 7 days, the cross-sectional areas of each muscle fiber type in the HU group decreased. Those were prevented in the ES+IC group rather than the ES group. The expression of heat shock protein 72 was enhanced in the ES and ES+IC groups. These results indicated that although electrical stimulation is effective to prevent muscle atrophy, the combination of electrical stimulation and isometric contraction have further effect. PMID:21619551

  13. Raman scattering and electrical resistance of highly disordered graphene

    NASA Astrophysics Data System (ADS)

    Shlimak, I.; Haran, A.; Zion, E.; Havdala, T.; Kaganovskii, Yu.; Butenko, A. V.; Wolfson, L.; Richter, V.; Naveh, D.; Sharoni, A.; Kogan, E.; Kaveh, M.

    2015-01-01

    Raman scattering (RS) spectra and current-voltage characteristics at room temperature were measured in six series of small samples fabricated by means of electron-beam lithography on the surface of a large size (5 ×5 mm) industrial monolayer graphene film. Samples were irradiated by different doses of C + ion beam up to 1015 cm -2 . It was observed that at the utmost degree of disorder, the Raman spectra lines disappear which is accompanied by the exponential increase of resistance and change in the current-voltage characteristics. These effects are explained by suggestion that highly disordered graphene film ceases to be continuous and splits into separate fragments. The relationship between structure (intensity of RS lines) and sample resistance is defined. It is shown that the maximal resistance of the continuous film is of the order of reciprocal value of the minimal graphene conductivity ? h /4 e2?20 kOhm.

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Perrone, A.

    2011-12-01

    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.

  16. Non-homogeneous extracellular resistivity affects the current-source density profiles of up-down state oscillations.

    PubMed

    Bazhenov, Maxim; Lonjers, Peter; Skorheim, Steven; Bedard, Claude; Dstexhe, Alain

    2011-10-13

    Rhythmic local field potential (LFP) oscillations observed during deep sleep are the result of synchronized electrical activities of large neuronal ensembles, which consist of alternating periods of activity and silence, termed 'up' and 'down' states, respectively. Current-source density (CSD) analysis indicates that the up states of these slow oscillations are associated with current sources in superficial cortical layers and sinks in deep layers, while the down states display the opposite pattern of source-sink distribution. We show here that a network model of up and down states displays this CSD profile only if a frequency-filtering extracellular medium is assumed. When frequency filtering was modelled as inhomogeneous conductivity, this simple model had considerably more power in slow frequencies, resulting in significant differences in LFP and CSD profiles compared with the constant-resistivity model. These results suggest that the frequency-filtering properties of extracellular media may have important consequences for the interpretation of the results of CSD analysis. PMID:21893529

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

    PubMed

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

    2013-05-01

    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

  18. Transcriptional Profiles Uncover Aspergillus flavus-Induced Resistance in Maize Kernels

    PubMed Central

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

    2011-01-01

    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. PMID:22069739

  19. Electrical Resistivity Imaging Below Nuclear Waste Tank Farms at the Hanford Site

    NASA Astrophysics Data System (ADS)

    Rucker, D. F.; Levitt, M. T.

    2006-12-01

    The Hanford Site, a Department of Energy nuclear processing facility in eastern Washington, contains a complex series of radiological liquid waste disposal and storage facilities. The primary method of interim storage is the use of large single-shelled steel tanks with capacities of up to 3790 m3 (1 million gallons). The tanks are organized below ground into tank farms, with about 12 tanks per farm. The liquid waste within the tanks is primarily comprised of inorganic salts with minor constituents of heavy metals and radiological metals. The electrical properties of the radiological waste are significantly different to that of the surrounding engineered fill and native geologic formations. Over the past 60 years since the earliest tanks have been in use, many have been known to leak. An electrical resistivity survey was conducted within a tank farm to map the extent of the plumes resulting from historic leaks. Traditional surface-based electrical resistivity surveys resulted in unusable data due to the significant subsurface infrastructure that included a network of delivery pipes, wells, fences, and electrical discharge sources . HGI adapted the resistivity technique to include the site infrastructure as transceivers to augment data density and geometry. The results show a distribution of low resistivity values within the farm in areas that match known historic leak sites. The addition of site infrastructure as sensors demonstrates that the electrical resistivity technique can be used in highly industrial sites.

  20. Electrical Resistivity—Hydraulic Conductivity Relationships in Glacial Outwash Aquifers

    NASA Astrophysics Data System (ADS)

    Urish, Daniel W.

    1981-10-01

    Empirical field relationships between the apparent formation factors from surface resistivity soundings and hydraulic conductivity from pumping tests in fresh water granular aquifers usually show positive correlations. These relationships can be adequately explained by theory if consideration is taken of in situ field conditions. A sound theoretical basis for relating apparent formation factor to pertinent hydrogeophysical parameters in homogeneous isotropic sand is a three-phase parallel resistor model which explicity includes parameters of porewater resistivity, grain size and shape, porosity, tortuosity, and intergranular surface conductance. The veracity of the theoretical model is supported by data from laboratory tests. The model demonstrates that intergranular surface conductance is an important factor at small grain sizes and high porewater resistivities, operating to lower the apparent formation factor. The model further shows that direct relationships between hydraulic conductivity and formation factor are weak in the normal range of porewater resistivity, being strongly dependent on porosity. When systematic variation of in situ porosity and aquifer layering effects are considered, a simulated field curve relating the apparent formation factor to hydraulic conductivity is shown to compare favorably with the comparable curve from field data for thirteen pumping test sites in southern Rhode Island. Both theoretical and empirical results demonstrate a useful positive correlation between aquifer apparent formation factor and hydraulic conductivity. Quantitative interpretation, however, is imprecise because of nonuniqueness of interpretation and inherent variation in important aquifer parameters, especially porosity.

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

    PubMed Central

    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

    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

  2. Non-invasive determination of absolute lung resistivity in adults using electrical impedance tomography.

    PubMed

    Zhang, Jie; Patterson, Robert

    2010-08-01

    Lung resistivity is a physiological parameter that describes the electrical characteristics of the lungs. Lung composition changes due to changes in the lung tissues, fluid and air volume. Various diseases that can cause a change in lung composition may be monitored by measuring lung resistivity. Currently, there is no accepted non-invasive method to measure lung resistivity. In this study, we presented a method and framework to non-invasively determine lung resistivity using electrical impedance tomography (EIT). By comparing actual measurements from subjects with data from a 3D human thorax model, an EIT image can be reconstructed to show a resistivity difference between the model and the subject. By adjusting the lung resistivity in the model, the resistivity difference in the lung regions can be reduced to near zero. This resistivity value then is the estimation of the lung resistivity of the subject. Using the proposed method, the lung resistivities of four normal adult males (43 +/- 13 years, 78 +/- 10 kg) in the supine position at air volumes starting at functional residual capacity (FRC--end expiration) and increasing in 0.5 l steps to 1.5 l were studied. The averaged lung resistivity changes 12.59%, from 1406 Omega cm to 1583 Omega cm, following the inspiration of 1.5 l air from FRC. The coefficients of variation (CV) of precision for the four subjects are less than 10%. The experiment was repeated five times at each air volume on a subject to test the reproducibility. The CVs are less than 3%. The results show that it is feasible to determine absolute lung resistivity using an EIT-based method. PMID:20647615

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

    SciTech Connect

    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

    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.

  4. Interrelation between the electrical resistance of amorphous alloys and their atomic and electronic structures

    NASA Astrophysics Data System (ADS)

    Zakharenko, M. I.; Kalnysh, T. V.; Semen'ko, M. P.

    2012-08-01

    Based on the results of the investigations of temperature dependences of electrical resistance of a number of iron-based amorphous metallic alloys, a model of electrical resistance that takes into account the common features of the atomic and electronic structures of these alloys has been developd. It has been established that the alloying of these materials by elements that are located to the left of Fe in the periodic table leads to a nonlinearity, which is described satisfactorily by the T 1/2 law. This feature is explained by the phenomenon of weak localization in cluster structures formed around an alloying atom. The origin of such a localization is considered with allowance for the electron structure, which makes it possible to explain some singularities in the temperature dependences of the electrical resistance.

  5. 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

    Viard, Jerome; Khantine-Langlois, Francoise

    2001-01-01

    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)

  6. Electrical Resistivity of Silane Multiply Shock-Compressed to 106 GPa

    NASA Astrophysics Data System (ADS)

    Zhong, Xiao-Feng; Liu, Fu-Sheng; Cai, Ling-Cang; Xi, Feng; Zhang, Ming-Jian; Liu, Qi-Jun; Wang, Ya-Ping; Hao, Bin-Bin

    2014-12-01

    The liquid silane sample, prepared by liquifying pure silane gas at 88.5 K, is multiply shock-compressed to 106 GPa by means of a two-stage light-gas gun and a coolant target system. Electrical resistivity is measured for fluid silane during the period of multi-shock compression in the pressure range from 63.5 GPa to 106 GPa. It is shown that the electrical resistivity reduces to the order of 10?3–10?4 ohm·m after the second shock arrived, which is two orders higher than those of typical melt metals. Though the metallization transition could not be confirmed under the loading condition of our shock experiments, its resistivity drops sharply along with the pressure rise. The phenomenon might be caused by silane decomposed during the pressure loading, due to the fact that, above 100 GPa, we find that its resistivity is close to hydrogen under the same pressure.

  7. A digitally controlled system for effecting and presenting a selected electrical resistance

    NASA Technical Reports Server (NTRS)

    Fletcher, James C. (inventor); Ross, Walter L. (inventor)

    1989-01-01

    A digitally controlled resistance generator is described, in which resistors having values selected according to an expression 2(sup N-1)(R), where N is equal to the number of terms in the expression, and R is equal to the lowest value of resistance, are electrically inserted into a resistive circuit in accordance with a parallel binary signal provided by an analog-to-digital converter or a programmable computer. This binary signal is coupled via optical isolators which, when activated by a logical 1, provides a negative potential to some or all of the gate inputs of the normally on field effect transistors which, when on, shorts out the associated resistor. This applied negative potential turns the field effect transistors off and electrically inserts the resistor coupled between the source terminal and the drain terminal of that field effect transistor into the resistive circuit between the terminals.

  8. Stochastic Inversion of Electrical Resistivity Changes Using a Markov Chain, Monte Carlo Approach

    SciTech Connect

    Ramirez, A; Nitao, J; Hanley, W; Aines, R; Glaser, R; Sengupta, S; Dyer, K; Hickling, T; Daily, W

    2004-09-21

    We describe a stochastic inversion method for mapping subsurface regions where the electrical resistivity is changing. The technique combines prior information, electrical resistance data and forward models to produce subsurface resistivity models that are most consistent with all available data. Bayesian inference and a Metropolis simulation algorithm form the basis for this approach. Attractive features include its ability to: (1) provide quantitative measures of the uncertainty of a generated estimate and, (2) allow alternative model estimates to be identified, compared and ranked. Methods that monitor convergence and summarize important trends of the posterior distribution are introduced. Results from a physical model test and a field experiment were used to assess performance. The stochastic inversions presented provide useful estimates of the most probable location, shape, and volume of the changing region, and the most likely resistivity change. The proposed method is computationally expensive, requiring the use of extensive computational resources to make its application practical.

  9. Genetic mapping and transcription analyses of resistance gene loci in potato using NBS profiling.

    PubMed

    Brugmans, Bart; Wouters, Doret; van Os, Hans; Hutten, Ronald; van der Linden, Gerard; Visser, Richard G F; van Eck, Herman J; van der Vossen, Edwin A G

    2008-11-01

    NBS profiling is a method for the identification of resistance gene analog (RGA) derived fragments. Here we report the use of NBS profiling for the genome wide mapping of RGA loci in potato. NBS profiling analyses on a minimal set of F1 genotypes of the diploid mapping population previously used to generate the ultra dense (UHD) genetic map of potato, allowed us to efficiently map polymorphic RGA fragments relative to 10,000 existing AFLP markers. In total, 34 RGA loci were mapped, of which only 13 contained RGA sequences homologous to RGAs genetically positioned at approximately similar positions in potato or tomato. The remaining RGA loci mapped either at approximate chromosomal regions previously shown to contain RGAs in potato or tomato without sharing homology to these RGAs, or mapped at positions not yet identified as RGA-containing regions. In addition to markers representing RGAs with unknown functions, segregating markers were detected that were closely linked to four functional R genes that segregate in the UHD mapping population. To explore the potential of NBS profiling in RGA transcription analyses, RNA isolated from different tissues was used as template for NBS profiling. Of all the fragments amplified approximately 15% showed putative intensity or absent/present differences between different tissues suggesting putative tissue specific RGA or R gene transcription. Putative absent/present differences between individuals were also found. In addition to being a powerful tool for generating candidate gene markers linked to R gene loci, NBS profiling, when applied to cDNA, can be instrumental in identifying those members of an R gene cluster that are transcribed, and thus putatively functional. PMID:18806994

  10. Procedure for contact electrical resistance measurements as developed for use at Sandia National Laboratories

    SciTech Connect

    Finch, J.L.

    1994-06-01

    Military Specifications call out general procedures and guidelines for conducting contact resistance measurements on chemical conversion coated panels. This paper deals with a test procedure developed at Sandia National Laboratories used to conduct contact electrical resistance on non-chromated conversion coated test panels. MIL-C-81706 {open_quotes}Chemical Conversion Materials For Coating Aluminum and Aluminum Alloys{close_quotes} was the reference specification used for guidance.

  11. Using electrical resistivity tomography to differentiate sapwood from heartwood: application to conifers.

    PubMed

    Guyot, Adrien; Ostergaard, Kasper T; Lenkopane, Mothei; Fan, Junliang; Lockington, David A

    2013-02-01

    Estimating sapwood area is one of the main sources of error when upscaling point scale sap flow measurements to whole-tree water use. In this study, the potential use of electrical resistivity tomography (ERT) to determine the sapwood-heartwood (SW-HW) boundary is investigated for Pinus elliottii Engelm var. elliottii?×?Pinus caribaea Morelet var. hondurensis growing in a subtropical climate. Specifically, this study investigates: (i) how electrical resistivity is correlated to either wood moisture content, or electrolyte concentration, or both, and (ii) how the SW-HW boundary is defined in terms of electrical resistivity. Tree cross-sections at breast height are analysed using ERT before being felled and the cross-section surface sampled for analysis of major electrolyte concentrations, wood moisture content and density. Electrical resistivity tomography results show patterns with high resistivities occurring in the inner part of the cross-section, with much lower values towards the outside. The high-resistivity areas were generally smaller than the low-resistivity areas. A comparison between ERT and actual SW area measured after felling shows a slope of the linear regression close to unity (=0.96) with a large spread of values (R(2)?=?0.56) mostly due to uncertainties in ERT. Electrolyte concentrations along sampled radial transects (cardinal directions) generally showed no trend from the centre of the tree to the bark. Wood moisture content and density show comparable trends that could explain the resistivity patterns. While this study indicates the potential for application of ERT for estimating SW area, it shows that there remains a need for refinement in locating the SW-HW boundary (e.g., by improvement of the inversion method, or perhaps electrode density) in order to increase the robustness of the method. PMID:23329335

  12. Compact Models of Spreading Resistances for Electrical\\/Thermal Design of Devices and ICs

    Microsoft Academic Search

    Shreepad Karmalkar; P. Vishnu Mohan; Hari P. Nair; Ramya Yeluri

    2007-01-01

    Building upon our recent work (IEEE Electron Device Lett., vol. 26, pp. 909-912, Dec, 2005), we present simple and continuous closed-form models for several rectangular and circular spreading resistance geometries encountered in electrical\\/thermal design of devices and integrated circuits. The resistance geometries considered involve current\\/heat flow between parallel contacts of rectangular or circular shape and concentric or eccentric nature, between

  13. Contact resistance and fretting corrosion of lead-free alloy coated electrical contacts

    Microsoft Academic Search

    Ji Wu; Michael G. Pecht

    2006-01-01

    As lead-free solders replace tin-lead solders in soldering, it is also expected that lead-free solder alloys will be used as contact finish materials for electrical contacts. In this study, the contact resistance and fretting corrosion of tin-silver-copper and tin-copper coatings were investigated and compared with tin-lead eutectic coating. The contact resistance before and after different aging conditions, including mixed flowing

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

    NASA Astrophysics Data System (ADS)

    Moloney, Padraig G.

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

  15. Electrical resistivity behavior of substituted perovskite manganates sintered at different temperatures

    Microsoft Academic Search

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

    1999-01-01

    Temperature dependence of the electrical resistivity of La1-xCxMnO3 (x =\\u000a 0.2, 0.3) samples sintered at two different temperatures are compared to\\u000a understand the origin of the double-maxima-type resistivity curves of\\u000a some doped perovskite manganates reported in the literature. It is shown\\u000a that compositional inhomogeneity is responsible for the anomalous\\u000a electrical properties of the substituted manganate samples processed at\\u000a low temperatures.

  16. Hydrogeophysical estimation of groundwater tracer concentrations from field-scale electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Singha, Kamini

    This research has established a systematic procedure to accurately track the migration of a groundwater solute tracer using cross-well electrical resistivity tomography (ERT). There are three contributions in this dissertation. First, based on original experimental data collected for this project at the Massachusetts Military Reservation, it is shown that the migration of a saline tracer was readily detected in 3D using ERT, and that the mass, center of mass, and spatial variance of the imaged tracer plume were estimated from modified moment analysis of the electrical resistivity tomograms. Conversion of the inverted electrical resistivities to solute concentrations via Archie's law resulted in significant underestimation of tracer mass and greater apparent dispersion than that suggested by reasonable advection-dispersion simulations. However, the center of mass estimated from ERT inversions was accurately tracked when compared to 3D transport simulation. The second contribution presented in this dissertation is to reveal how the spatially variable resolution of ERT affects electrical resistivity estimates and local solute concentrations. Underestimated tracer mass from ERT and overestimated tracer plume dispersion is shown to be an effect of two properties of ERT surveys: (1) reduced measurement sensitivity to electrical resistivity values with distance from the electrodes and, (2) spatial smoothing (regularization) resulting from tomographic inversion. Analyses suggest that no single petrophysical relation, such as Archie's law, exists between concentration and electrical resistivity. The "correct" petrophysical model must vary both in space and time. Finding this non-stationary petrophysical model is the third contribution of this research. A method is demonstrated that employs numerical simulation of both solute transport and electrical flow to create local non-stationary linear relations between resistivities and tracer concentrations. These relations are used to convert field electrical resistivity tomograms into estimated concentrations. In both synthetic and field data, tracer mass and concentration estimates obtained using this non-stationary estimation approach were superior to those obtained using direct application of Archie's law applied to 3D tomograms from ERT. Through dynamic geophysical imaging of a groundwater tracer combined with quantification of the spatially variable resolution of ERT, a more accurate description of tracer behavior was achieved than previously possible.

  17. Corrosion resistance of chromium-coated 20895 electrical steel

    SciTech Connect

    Babich, S.G.; Zyabrev, A.A.; Skibina, G.B.; Vavilova, N.V. [N.E. Bauman State Technical Univ., Moscow (Russian Federation)

    1992-05-01

    In order to protect the magnetically soft 20895 electrical steel (0.03% C, 0.30% Mn, 0.30% Si, 0.20% P, 0.020% S, 0.030% Cu) from corrosion, the surface is alloyed with chromium using a circulation technique in a gaseous chloride medium at t = 950 and 1000{degrees}C for 1-9 h. 1 ref., 2 figs., 1 tab.

  18. Influence of fixed electric charges on potential profile across the squid axon membrane

    NASA Astrophysics Data System (ADS)

    Cortez, C. M.; Cruz, F. A. O.; Silva, D.; Costa, L. F.

    2008-03-01

    The potential profile for a model of squid axon membrane has been determined for two physiological states: resting and action states. The non-linear Poisson-Boltzmann equation has been solved by considering the volumetric charge densities due to charges dissolved in an electrolytic solution and fixed on both glycocalyx and cytoplasmatic proteins. Results showing the features of the potential profile along the outer electrolytic region are similar for both resting and action states. However, the potential fall along glycocalyx at action state is lower than at resting. A small variation in the Na + concentration drastically affects the surface membrane potentials and vice versa. We conclude that effects on the potential profile due to surface lipidic bilayer charge and contiguous electric double layers are more relevant than those provoked by fixed charges distributed along the cell cytoplasm.

  19. Mechanical flexible and electric fatigue resistant behavior of relaxor ferroelectric terpolymer

    NASA Astrophysics Data System (ADS)

    Fang, Fei; Yang, Wei; Yang, Wen

    2009-08-01

    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.

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

    PubMed

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

    2009-05-01

    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

  1. Abnormal drop in electrical resistivity with impurity doping of single-crystal Ag

    PubMed Central

    Kim, Ji Young; Oh, Min-Wook; Lee, Seunghun; Cho, Yong Chan; Yoon, Jang-Hee; Lee, Geun Woo; Cho, Chae-Ryong; Park, Chul Hong; Jeong, Se-Young

    2014-01-01

    Resistivity is an intrinsic feature that specifies the electrical properties of a material and depends on electron-phonon scattering near room temperature. Reducing the resistivity of a metal to its potentially lowest value requires eliminating grain boundaries and impurities, but to date few studies have focused on reducing the intrinsic resistivity of a pure metal itself. We could reduce the intrinsic resistivity of single-crystal Ag, which has an almost perfect structure, by impurity doping it with Cu. This paper presents our results: resistivity was reduced to 1.35???·cm at room temperature after 3?mol% Cu-doping of single-crystal Ag. Various mechanisms were examined in an attempt to explain the abnormal behavior. PMID:24965478

  2. Direct current resistivity profiling to study distribution of water in the unsaturated zone near the Amargosa Desert Research Site, Nevada

    USGS Publications Warehouse

    Abraham, Jared D.; Lucius, Jeffrey E.

    2004-01-01

    In order to study the distribution of water in the unsaturated zone and potential for ground-water recharge near the Amargosa Desert Research Site south of Beatty, Nevada, the U.S. Geological Survey collected direct-current resistivity measurements along three profiles in May 2003 using an eight-channel resistivity imaging system. Resistivity data were collected along profiles across the ADRS, across a poorly incised (distributary) channel system of the Amargosa River southwest of the ADRS, and across a well-incised flood plain of the Amargosa River northwest of the ADRS. This report describes results of an initial investigation to estimate the distribution of water in the unsaturated zone and to evaluate the shallow subsurface stratigraphy near the ADRS. The geophysical method of dc resistivity was employed by using automated data collection with numerous electrodes. 'Cross sections' of resistivity, produced by using an inversion algorithm on the field data, at the three field sites are presented and interpreted.

  3. Electrical resistivity characterization and defect detection on a geosynthetic clay liner (GCL) on an experimental site

    NASA Astrophysics Data System (ADS)

    Sirieix, C.; Fernández Martínez, J. L.; Riss, J.; Genelle, F.

    2013-03-01

    In this paper we analyze the onsite characterization of a geosynthetic clay liner (GCL) that serves to ensure the impermeability of a landfill cap by DC electrical methods. The imaging of the GCL geoelectrical properties is a challenging problem because it is a very thin (between 4 and 7 mm thick) and resistive layer (from 100,000 to 2,000,000 ?·m) depending on meteorological conditions and aging. We compare results obtained using electrical resistivity tomography (ERT) using two different kinds of arrays (dipole-dipole DD and Wenner-Schlumberger) on an experimental site with engineered defects. To confirm these results and to find the real onsite GCL resistivity we have performed sampling of the posterior distribution of this parameter using vertical electrical sounding (VES) inversions. Different VES methods were extracted from ERT with DD array and converted into a Schlumberger array. As a main conclusion the dipole-dipole array provides a better resistivity resolution of the defects than the Wenner-Schlumberger array. On ERT images, the defect detection seems to be impossible if the GCL has very high resistivity, as it happened when it was put in place. Taking into account the equivalence rules, the inversions are in both cases (ERT and VES) compatible. The GCL resistivity estimated from PSO (particle swarm optimization) varies from 3.0 105 to 1.106 ?·m depending on saturation conditions during the twenty first months of its placing. Then, the resistivity dropped to 4.104-9.104 ?·m, indicating a probable chemical damage of the GCL due to aging. Finally the fact that the VES inversions are solved via PSO sampling allows for the detection of a very thin and resistive layer and opens the possibility of performing micro VES surveys along the landfill to detect possible GCL defects.

  4. Fringing field effects on electrical resistivity of semiconductor nanowire-metal contacts

    E-print Network

    Liu, Yang

    Fringing field effects on electrical resistivity of semiconductor nanowire-metal contacts Jun Hu,1 2007; accepted 4 February 2008; published online 27 February 2008 Metal contacts play an important role contacts due to small contact cross sections. We numerically investigate certain unique properties

  5. Image Sticking Resistant Liquid Crystal Display Driven by Fringe Electric Field for Mobile Applicaitions

    Microsoft Academic Search

    Seung Min Seen; Mi Sook Kim; Seung Hee Lee

    2010-01-01

    We propose image sticking resistant liquid crystal display (LCD) driven by fringe electric field for mobile application. For use of an alignment layer with polyamic acid (PA) type without cross link agent, impurity ions absorbed on the alignment layer easily discharge irrespective of liquid crystal (LC) because there is not any cross link agent which prevents discharging the ions, resulting

  6. Thermal conductivity, electrical resistivity, and permeability of saturated soils at various porosities

    E-print Network

    Enderby, James Keith

    1981-01-01

    and electrical resist1vity of a sediment are functions of porosity and soil type. Since cuttings are ava11able during drilling, 1t is possible to determine simple index properties of the sediments . Tests, such as the Atterberg limits, can be used to give...

  7. CAMBIAL ELECTRICAL RESISTANCE DOES NOT ASSESS VITALITY OF INDIVIDUAL SWEET GUM TREES

    Microsoft Academic Search

    J. Clarki; R. Kjelgran; J. Hushagen; J. Fiore

    1992-01-01

    Cambial electrical resistance (CER) was as- sessed over a year-long period, using the Shigometer, for 109 sweetgum trees (Liquidambarstyraciflua) planted along streets in Seattle, Washington. CER decreased through the spring, reached a minimum in summer, increased through the fall and was maximal in mid-winter. The seasonal maximum was 200- 600% greater than the summer minimum. CER measurements could not be

  8. Author's personal copy In situ TEM studies of oxygen vacancy migration for electrically induced resistance

    E-print Network

    Wang, Wei Hua

    to this model, the oxygen vacancies (ions) are the active agents for resistance switching effect. The mobility oxides), the oxygen vacancies are mobile, while the cations sublattices are stable. It is believed MicronAuthor's personal copy In situ TEM studies of oxygen vacancy migration for electrically induced

  9. Estrous Cycle Patterns in Cattle Monitored by Electrical Resistance and Milk Progesterone

    Microsoft Academic Search

    G. S. Heckman; L. S. Katz; R. H. Foote; E. A. B. Oltenacu; N. R. Scott; R. A. Marshall

    1979-01-01

    An electronic probe with parallel stainless steel electrodes was designed to measure changes in electrical resistance in the anterior vagina associated with increased cervical mucus secretion at estrus. Three groups of Holsteins were probed, and a sample of residual milk after milking was taken for progesterone assay every 2nd day for 28 to 40 days. Group ! consisted of 29

  10. An automated, externally heated opposed anvil high pressure-high temperature system for electrical resistivity studies

    Microsoft Academic Search

    T. K. Mondal; S. Murugavel; S. Asokan

    1999-01-01

    A simple, externally heated opposed (Bridgman) anvil system has been developed for electrical resistivity measurements up to 8 GPa pressure and 400 °C. The whole system is automated, in which the application and measurement of pressure and heating of the sample are undertaken using an IBM PC and associated electronic and mechanical hardware. The system developed has a pressure control

  11. High School Students' Understanding of Resistance in Simple Series Electric Circuits.

    ERIC Educational Resources Information Center

    Liegeois, Laurent; Mullet, Etienne

    2002-01-01

    Studies the understanding that 8-12 grade high school students were able to develop with regard to the interrelationships between resistance, potential difference, and current concepts (Ohm's law). Explores the immediate effects of exposure to electricity courses on the intuitive mastery of these relationships. (Contains 32 references.)…

  12. MONITORING LANDFILL COVER BY ELECTRICAL RESISTIVITY1 TOMOGRAPHY ON AN EXPERIMENTAL SITE2

    E-print Network

    Paris-Sud XI, Université de

    1 MONITORING LANDFILL COVER BY ELECTRICAL RESISTIVITY1 TOMOGRAPHY ON AN EXPERIMENTAL SITE2 3 4 Abstract15 In France, the monitoring of landfill cover after closure of the site is a local problem, since36 Landfills (MSW). These sites consist of several cells which are covered once they are full of37

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

    SciTech Connect

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

    2011-12-01

    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.

  14. Deep Electrical Resistivity and Passive Seismic measurements for the characterization of a local geothermal resource at Canino (Viterbo, Italy)

    NASA Astrophysics Data System (ADS)

    Rizzo, E.; Delle Donne, D.; Murratzu, A.; Romano, G.; Votta, M.; Botteghi, S.; Manzella, A.; Fiaschi, S.; Ulivieri, G.

    2012-04-01

    Electrical resistivity and passive seismic methodologies are powerful tools for geothermal exploration, helping to constrain the geologic framework and the physical parameters of the geothermal system. We investigated the hydrogeological system of the Canino area (Viterbo - Central Italy) in order to constrain the depth of the reservoir rocks for potential geothermal exploitation. An intense hydrothermal activity is well indicated in the study area by many thermal springs with temperatures of ~50°C. The study area is characterized by a large travertine plain overlying Ligurian Units and Mesozoic carbonates of the Tuscan Nappe. These Mesozoic carbonates characterize also the Canino mountain range, bounding to the north the travertine plain, and representing the re-charge area of the hydrothermal system. The hydrogeological system is characterized by a shallow fluid circulation in a heterogeneous aquifer with different permeability. Previous geological and geochemical studies define the Canino geothermal system as a complex area where a simple model is not sufficient to explain the flow rate of thermal waters localized in the small carbonate outcrop. Therefore, to delineate the local geothermal use of the resource, which seems easily accessible, precise information is required. This work describes the geophysical, geological and hydrogeological investigation in order to characterize the geothermal resource. Two different geophysical methods were used to infer the position and the geometry of the carbonate rocks below the ground surface, where the geothermal resource should be localized. A Deep Electrical Resistivity Tomography was carried out along a profile 3000 m long to achieve an investigation depth of about 700 m. The resistivity data acquired by a geoelectrical system prototype were analysed and inverted by different algorithm to obtain the best tomography resistivity image. We also performed a passive seismic survey using spatial autocorrelation techniques. We acquired sixteen seismic measurements using an array of seven broad-band seismometers. We were able to evaluate the Rayleigh phase and group velocities in the 0.5 - 5 Hz frequency range, allowing us to investigate up to ~700 m deep. The results achieved from joint analysis of electrical resistivity and passive seismic surveys strongly indicates the position of the top of the carbonate reservoir rocks in the 350-410 m depth range. This information yields to define the position of the exploration target and thus to roughly estimate the cost of the future drilling operation.

  15. Metabolic Profiling for Detection of Staphylococcus aureus Infection and Antibiotic Resistance

    PubMed Central

    Näsström, Elin; Kouremenos, Konstantinos; Sundén-Cullberg, Jonas; Guo, YongZhi; Moritz, Thomas; Wolf-Watz, Hans; Johansson, Anders; Fallman, Maria

    2013-01-01

    Due to slow diagnostics, physicians must optimize antibiotic therapies based on clinical evaluation of patients without specific information on causative bacteria. We have investigated metabolomic analysis of blood for the detection of acute bacterial infection and early differentiation between ineffective and effective antibiotic treatment. A vital and timely therapeutic difficulty was thereby addressed: the ability to rapidly detect treatment failures because of antibiotic-resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) were used in vitro and for infecting mice, while natural MSSA infection was studied in humans. Samples of bacterial growth media, the blood of infected mice and of humans were analyzed with combined Gas Chromatography/Mass Spectrometry. Multivariate data analysis was used to reveal the metabolic profiles of infection and the responses to different antibiotic treatments. In vitro experiments resulted in the detection of 256 putative metabolites and mice infection experiments resulted in the detection of 474 putative metabolites. Importantly, ineffective and effective antibiotic treatments were differentiated already two hours after treatment start in both experimental systems. That is, the ineffective treatment of MRSA using cloxacillin and untreated controls produced one metabolic profile while all effective treatment combinations using cloxacillin or vancomycin for MSSA or MRSA produced another profile. For further evaluation of the concept, blood samples of humans admitted to intensive care with severe sepsis were analyzed. One hundred thirty-three putative metabolites differentiated severe MSSA sepsis (n?=?6) from severe Escherichia coli sepsis (n?=?10) and identified treatment responses over time. Combined analysis of human, in vitro, and mice samples identified 25 metabolites indicative of effective treatment of S. aureus sepsis. Taken together, this study provides a proof of concept of the utility of analyzing metabolite patterns in blood for early differentiation between ineffective and effective antibiotic treatment in acute S. aureus infections. PMID:23451124

  16. Effector Genomics Accelerates Discovery and Functional Profiling of Potato Disease Resistance and Phytophthora Infestans Avirulence Genes

    PubMed Central

    Vleeshouwers, Vivianne G. A. A.; Rietman, Hendrik; Krenek, Pavel; Champouret, Nicolas; Young, Carolyn; Oh, Sang-Keun; Wang, Miqia; Bouwmeester, Klaas; Vosman, Ben; Visser, Richard G. F.; Jacobsen, Evert; Govers, Francine; Kamoun, Sophien; Van der Vossen, Edwin A. G.

    2008-01-01

    Potato is the world's fourth largest food crop yet it continues to endure late blight, a devastating disease caused by the Irish famine pathogen Phytophthora infestans. Breeding broad-spectrum disease resistance (R) genes into potato (Solanum tuberosum) is the best strategy for genetically managing late blight but current approaches are slow and inefficient. We used a repertoire of effector genes predicted computationally from the P. infestans genome to accelerate the identification, functional characterization, and cloning of potentially broad-spectrum R genes. An initial set of 54 effectors containing a signal peptide and a RXLR motif was profiled for activation of innate immunity (avirulence or Avr activity) on wild Solanum species and tentative Avr candidates were identified. The RXLR effector family IpiO induced hypersensitive responses (HR) in S. stoloniferum, S. papita and the more distantly related S. bulbocastanum, the source of the R gene Rpi-blb1. Genetic studies with S. stoloniferum showed cosegregation of resistance to P. infestans and response to IpiO. Transient co-expression of IpiO with Rpi-blb1 in a heterologous Nicotiana benthamiana system identified IpiO as Avr-blb1. A candidate gene approach led to the rapid cloning of S. stoloniferum Rpi-sto1 and S. papita Rpi-pta1, which are functionally equivalent to Rpi-blb1. Our findings indicate that effector genomics enables discovery and functional profiling of late blight R genes and Avr genes at an unprecedented rate and promises to accelerate the engineering of late blight resistant potato varieties. PMID:18682852

  17. Effector genomics accelerates discovery and functional profiling of potato disease resistance and phytophthora infestans avirulence genes.

    PubMed

    Vleeshouwers, Vivianne G A A; Rietman, Hendrik; Krenek, Pavel; Champouret, Nicolas; Young, Carolyn; Oh, Sang-Keun; Wang, Miqia; Bouwmeester, Klaas; Vosman, Ben; Visser, Richard G F; Jacobsen, Evert; Govers, Francine; Kamoun, Sophien; Van der Vossen, Edwin A G

    2008-01-01

    Potato is the world's fourth largest food crop yet it continues to endure late blight, a devastating disease caused by the Irish famine pathogen Phytophthora infestans. Breeding broad-spectrum disease resistance (R) genes into potato (Solanum tuberosum) is the best strategy for genetically managing late blight but current approaches are slow and inefficient. We used a repertoire of effector genes predicted computationally from the P. infestans genome to accelerate the identification, functional characterization, and cloning of potentially broad-spectrum R genes. An initial set of 54 effectors containing a signal peptide and a RXLR motif was profiled for activation of innate immunity (avirulence or Avr activity) on wild Solanum species and tentative Avr candidates were identified. The RXLR effector family IpiO induced hypersensitive responses (HR) in S. stoloniferum, S. papita and the more distantly related S. bulbocastanum, the source of the R gene Rpi-blb1. Genetic studies with S. stoloniferum showed cosegregation of resistance to P. infestans and response to IpiO. Transient co-expression of IpiO with Rpi-blb1 in a heterologous Nicotiana benthamiana system identified IpiO as Avr-blb1. A candidate gene approach led to the rapid cloning of S. stoloniferum Rpi-sto1 and S. papita Rpi-pta1, which are functionally equivalent to Rpi-blb1. Our findings indicate that effector genomics enables discovery and functional profiling of late blight R genes and Avr genes at an unprecedented rate and promises to accelerate the engineering of late blight resistant potato varieties. PMID:18682852

  18. 2D Magnetotelluric interpretation of the crust electrical resistivity across the Pampean terrane Río de la Plata suture, in central Argentina

    NASA Astrophysics Data System (ADS)

    Favetto, Alicia; Pomposiello, Cristina; López de Luchi, Mónica G.; Booker, John

    2008-11-01

    Magnetotelluric data were obtained along a 450 km, almost west-east profile at approximately 31.5° S, which extends from La Rioja to Santa Fé provinces in central Argentina. The profile crosses two main crustal domains that were juxtaposed during the Early-Middle Cambrian Pampean Orogeny: the Pampean terrane to the west and the Río de la Plata craton to the east. The electrical resistivity structure of the crustal domains together with their boundary is presented. Through dimensionality analysis of the data, it was demonstrated that regional-scale electrical structures are mainly two-dimensional with a strike direction oriented parallel to the surface geological strike. The resistivity model shows a subvertical limit approximately along the eastern border of the Sierra Chica de Córdoba. To the east, the shallower structure is the Chaco-Paranense basin extending to a depth of 6 km with resistivities between 1 and 30 Ohm-m, whereas below the basin the ca 2.1-2.3 Ga Río de la Plata craton shows resistivities in a range of 300-10,000 Ohm-m. The Pampean terrane presents a 6 km layer with a resistivity higher than 10,000 Ohm-m whereas below this layer the resistivity values range from 50 to 200 Ohm-m. Based on both the geological information and the magnetotelluric results, the sharp lateral discontinuity observed in the resistivity model to the east of the Sierras de Córdoba is conjectured to represent the boundary between the Río de la Plata craton and the Pampean terrane which may correspond to the Early Cambrian suture.

  19. 3D Electrical Resistivity Imaging to Predict Slope Failure in USM Campus, Penang, Malaysia

    NASA Astrophysics Data System (ADS)

    Moussa, Hussein A.; Nawawi, Mohd M. N.; Abdullah, Khiruddin

    2010-07-01

    3D electrical resistivity imaging was carried out to monitor slope failure in the USM campus. The natural disasters that occur suddenly such as landslides can cause loss of life, and money by damaging roads and cars. The prediction of a landslide before it occurs will reduce or stop these hazards. Geophysical techniques can be used to image slopes and monitor slope failure. The geophysical technique that was used in this study is electrical resistivity imaging. The results from the resistivity sections show that there are two different regions made up of granite, and sand zone. The results show that there are two factors which make the landslide possible. The first factor is the subsurface boulders and the other factor is saturated sand which may results subsidence of the surface.

  20. Structure-property relationships in Waspaloy via small angle scattering and electrical resistivity measurements

    SciTech Connect

    Whelchel, R. [Georgia Institute of Technology; Gerhardt, Dr. Rosario [Georgia Institute of Technology; Littrell, Ken [ORNL

    2010-01-01

    The mechanical properties in superalloys are controlled by the distribution of the {gamma}{prime} precipitate phase. Electrical measurements have been shown to be sensitive to certain aspects of the precipitation process and show promise for predicting the evolving microstructural state in superalloys. Aging experiments were conducted on Waspaloy samples for temperatures between 600 and 950 C for times ranging from 2min to 500h. Particle size distributions were obtained by modeling of small angle scattering (SAS) data, whereas, small precipitate size information, strain, and lattice mismatch data were obtained from X-ray diffraction. The microstructural information was then used to create a figure of merit of electron scattering intended to correlate electrical properties to the precipitate microstructure. The proposed figure of merit shows an empirical correlation with the electrical resistivity data, demonstrating the sensitivity of the resistivity measurements to the precipitation process and coarsening behavior.

  1. Implications for the lithospheric geometry of the Iapetus suture beneath Ireland based on electrical resistivity models from deep-probing magnetotellurics

    NASA Astrophysics Data System (ADS)

    Rao, C. K.; Jones, Alan G.; Moorkamp, Max; Weckmann, Ute

    2014-08-01

    Broad-band and long period magnetotelluric (MT) data were acquired at 39 stations along five NNW-SSE profiles crossing the Iapetus Suture Zone (ISZ) in Ireland. Regional strike analyses indicate that the vast majority of the MT data is consistent with an assumption of a 2-D geo-electric strike direction. Strike is N52°E for the three easternmost profiles and N75°E for the two westernmost profiles; these directions correlate well with the observed predominant geological strike of the study region. 2-D inversions of the galvanic distortion-corrected TE and TM mode data from each profile are shown and discussed. As mapped geological variations between the neighbouring profiles suggest a heterogeneous subsurface, it is important to verify the robustness of the presence and geometries of prominent conductivity anomalies by employing 3-D forward and inverse modelling. A high conductivity layer (resistivity of 1-10 ?m), found at middle to lower crustal depths and presumed to be indicative of metamorphosed graphitic sediments rich in sulphides deposited during the convergence of the Laurentian and Avalonian continents, essentially constitutes the electrical signature of the ISZ. Shallow conductors observed are probably due to black shales that were widely deposited within the sedimentary accretionary wedge during Ordovician time. We interpret the moderately low resistivity at shallow depths from west to east across Ireland as indicative of an increase in maturity of the black shales in the easterly direction. From our conductivity models the southern extent of the ISZ is inferred to lie between the Navan Silvermines Fault and the Navan Tipperary Line, and shows clear resistivity contrast along all the profiles at the southern MT stations. The change in resistivity deduced from the 2-D models is spatially related to the composition of Lower Palaeozoic Ordovician, Silurian, Devonian and Carboniferous rocks. At upper mantle depths of about 60 km, a high conductivity block below the central MT stations is found to lie within the accretionary wedge of the Iapetus suture, and the location of the conductive anomaly corroborates reasonably well with the inferred spreading head of the putative Iceland plume-related magmatic intrusion. The low resistivity upper crust beneath the ISZ is indeed rich in Ordovician rocks with black shale content in the eastern as well as the central part; the western part is largely underlain by a highly resistive block of volcanic and metamorphosed rocks forming crystalline basement.

  2. Characterization of Soils and Tertiary-Quaternary Sediments by Electrical Resistivity Tomography in Terra Chá, Lugo, Spain

    NASA Astrophysics Data System (ADS)

    Marinho, M. A.; Raposo, J. R.; Valcárcel Armesto, M.; Dafonte Dafonte, J.; Paz González, A.

    2012-04-01

    Electrical Resistivity Tomography (ERT) is a very attractive tool to describe the spatial and temporal variability of soil properties without digging. The electrical resistivity is a function of a number of soil properties, including particle size distribution, mineralogy, porosity, water content, temperature, etc. The main advantage of ERT relies on the fact that it neither disturbs the structure nor the water dynamics of the soil. In our work, ERT was used as a non-invasive method for measuring 2-D ERT profiles at three different scales according to the distance between electrodes, to guarantee different sensitivity to horizontal and vertical heterogeneities investigation. The experiment was conducted in an experimental field devoted to grassland at Castro de Ribeiras de Lea, Lugo Province, Spain. The studied soil is an Umbric Fluvaquent (Fluvisol umbrico) developed from Quaternary sediments, highly heterogeneous in depth because of the contrasting texture of the successive soil horizons and geological strata. So the loamy top soil horizons are developed over coarse gravelly Quaternary sediments, which in turn are underlain with Tertiary clayey sediments. ERT measurements were taken using an ABEM 1000 equipment, with a Wenner array of 48 electrodes. Electrodes were spaced at 0.2, 0.5 and 5.0 m to record resistivity along transects of 8, 20 and 200 m, respectively, and successive increased depth. Measurements were repeated along time during dry and wet seasons to evaluate the effect of contrasting soil water content on resistivity. A mathematical inversion was performed to convert the volumetric apparent resistivity into interpreted resistivity data. Results were used for: 1) identifying soil horizon thickness, 2) characterizing the homogeneity of topsoil horizons and 3) assessing soil water penetration during the rewetting period from the soil surface to the Quaternary and Tertiary subsoil layers. Acknowledgments. This work was funded in part by Spanish Ministry of Science and Innovation (MICINN) in the frame of project CGL2009-13700-C02. Financial support from CAPES/GOV., Brazil, is also acknowledged by Prof. M. Marinho.

  3. Characterization and calibration of seawater intrusion models using electrical resistivity tomography (Invited)

    NASA Astrophysics Data System (ADS)

    Nguyen, F. H.; Kemna, A.; Antonsson, A.; Engesgaard, P. K.; Beaujean, J.

    2009-12-01

    The urban development of coastal regions create seawater intrusion (SWI) problems which threatens groundwater quality and coastal ecosystems. To study SWI, one needs both robust measuring technologies, and reliable predictions. A key aspect in the calibration of SWI models involves reproducing measured groundwater chloride concentrations. Drilling such multi-screen wells to obtain a whole concentration profile is a risky task if reliable information about the position of the salt wedge is not available. Electrical resistivity tomography (ERT) is increasingly being used to characterize seawater intrusion and constrain corresponding models, given its high sensitivity to ion concentration in groundwater and its relatively high spatial resolution. We have investigated the potential of ERT using field data from a site in Almeria, SE Spain and synthetic data. Simulations have been run for several scenarios, with a simple hydrogeological model reflecting the local site conditions. The simulations showed that only the lower salt concentrations of the seawater-freshwater transition zone could be recovered, due to the loss of resolution with depth. We quantified this capability in terms of image appraisal indicators (cumulative sensitivity) associated with the measurement setup and showed that the mismatch between the targeted and imaged parameter values occurs from a certain threshold. Similarly, heterogeneity may only be determined accurately if located in an adequately sensitive area. Inversion of the synthetic data was performed by coupling an inversion code (PEST) with a finite-difference density-dependent flow and transport modeling code (HTS). The numerical results demonstrate the capacity of sensitivity-filtered ERT images to constrain transverse hydraulic dispersivity and longitudinal hydraulic conductivity of homogeneous seawater intrusion models. At the field site, we identified SWI at the scale of a few kilometers down to a hundred meters. Borehole logs show a remarkable correlation with the image obtained from surface data but indicate that the electrically derived mass fraction of pure seawater could not be recovered due to the discrepancy between the in-situ and laboratory-derived petrophysical relationships. Inversion of hydrologic model parameters using the field ERT image was not possible due to the inadequacy of a 2D representation of the geology at the site. Using ERT-derived data to estimate hydrological parameters requires to address resolution loss issues and the non-stationarity of the petrophysical relationship. The first issue may be approached using objective criteria. The most crucial limitation, however, is probably the non-stationarity of the petrophysical relationship. This is currently being investigated using more realistic models based on geostatistical modeling (SGeMS) of the petrophysical properties of a coastal aquifer and for transient simulations.

  4. Aerodynamic resistance reduction of electric and hybrid vehicles

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The generation of an EHV aerodynamic data base was initiated by conducting full-scale wind tunnel tests on 16 vehicles. Zero-yaw drag coefficients ranged from a high of 0.58 for a boxey delivery van and an open roadster to a low of about 0.34 for a current 4-passenger prototype automobile which was designed with aerodynamics as an integrated parameter. Characteristic effects of aspect ratio or fineness ratio which might appear if electric vehicle shape proportions were to vary significantly from current automobiles were identified. Some preliminary results indicate a 5 to 10% variation in drag over the range of interest. Effective drag coefficient wind-weighting factors over J227a driving cycles in the presence of annual mean wind fields were identified. Such coefficients, when properly weighted, were found to be from 5 to 65% greater than the zero-yaw drag coefficient in the cases presented. A vehicle aerodynamics bibliography of over 160 entries, in six general categories is included.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  6. Antimicrobial Resistance, Toxinotype, and Genotypic Profiling of Clostridium difficile Isolates of Swine Origin

    PubMed Central

    Fry, Pamela R.; Thakur, Siddhartha; Abley, Melanie

    2012-01-01

    The occurrence of Clostridium difficile infections in patients that do not fulfill the classical risk factors prompted us to investigate new risk factors of disease. The goal of this study was to characterize strains and associated antimicrobial resistance determinants of C. difficile isolated from swine raised in Ohio and North Carolina. Genotypic approaches used include PCR detection, toxinotyping, DNA sequencing, and pulsed-field gel electrophoresis (PFGE) DNA fingerprinting. Thirty-one percent (37/119) of isolates carried both tetM and tetW genes. The ermB gene was found in 91% of isolates that were resistant to erythromycin (68/75). Eighty-five percent (521/609) of isolates were toxin gene tcdB and tcdA positive. A total of 81% (494/609) of isolates were positive for cdtB and carry a tcdC gene (a toxin gene negative regulator) with a 39-bp deletion. Overall, 88% (196/223) of pigs carry a single C. difficile strain, while 12% (27/223) of pigs carried multiple strains. To the best of our knowledge, this is the first report of individual pigs found to carry more than one strain type of C. difficile. A significant difference in toxinotype profiles in the two geographic locations was noted, with a significantly (P < 0.001) higher prevalence of toxinotype V found in North Carolina (84%; 189/224) than in Ohio (55%; 99/181). Overall, the study findings indicate that significant proportions of C. difficile in swine are toxigenic and often are associated with antimicrobial resistance genes, although they are not resistant to drugs that are used to treat C. difficile infections. PMID:22518873

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

    SciTech Connect

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

    1994-09-01

    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.

  8. Electrical resistivity of rhenium in the solid and liquid states in relation to its enthalpy and heat of fusion

    SciTech Connect

    Dolomanov, L.A.; Kovalev, K.S.; Lebedev, S.V.; Savvatimskii, A.I.

    1988-05-01

    The electrical resistivity of rhenium was studied by the pulse method. The passage of an electric current through the specimen for a period of 5 x 10/sup -5/ sec introduced an amount of energy ranging from 0 to 1240 J/g. Measurements were made of the heat of fusion and electrical resistivity for the solid and liquid states, particularly the melting point. The results obtained were compared with the literature data.

  9. Local Resistance Profiling of Ultra Shallow Junction Annealed with Combination of Spike Lamp and Laser Annealing Processes using Scanning Spreading Resistance Microscope

    NASA Astrophysics Data System (ADS)

    Abo, Satoshi; Nishikawa, Kazuhisa; Ushigome, Naoya; Wakaya, Fujio; Iwamatsu, Toshiaki; Oda, Hidekazu; Takai, Mikio

    2011-01-01

    Local resistance profiles of ultra shallow boron and arsenic implanted into silicon with energies of 2.0 and 4.0 keV and doses of 2.0×1015 and 1.0×1015 ions/cm2 activated by a combination of conventional spike lamp and laser annealing processes were measured by scanning spreading resistance microscope (SSRM) with a depth resolution of less than 10 nm. The lowest local resistance at the low resistance region in 2.0 keV boron implanted silicon with 1050 °C spike lamp annealing followed by 0.35 kW/mm2 laser annealing was half of that without laser annealing. The lowest local resistance at the low resistance region in the arsenic implanted silicon activated by 1050 °C spike lamp annealing followed by 0.39 kW/mm2 laser annealing was 74% lower than that followed by 0.36 kW/mm2 laser annealing. The lowest local resistances at the low resistance regions in the arsenic implanted silicon with 0.36 and 0.39 kW/mm2 laser annealing followed by 1050 °C spike lamp annealing were 41 and 33% lower than those with spike lamp annealing followed by laser annealing. Laser annealing followed by spike lamp annealing could suppress the diffusion of the impurities and was suitable for making the ultra shallow and low resistance regions.

  10. Velocity profiles of electric-field-induced backflows in liquid crystals confined between parallel plates

    NASA Astrophysics Data System (ADS)

    Tsuji, Tomohiro; Chono, Shigeomi; Matsumi, Takanori

    2015-02-01

    For the purpose of developing liquid crystalline microactuators, we visualize backflows induced between two parallel plates for various parameters such as the twist angle, cell gap, applied voltage, and molecular configuration mode. We use 4-cyano-4'-pentyl biphenyl, a typical low-molar-mass nematic liquid crystal. By increasing the twist angle from 0° to 180°, the velocity component parallel to the anchoring direction of the lower plate changes from an S-shaped profile to a distorted S-shaped profile before finally becoming unidirectional. In contrast, the velocity component perpendicular to the anchoring direction evolves from a flat profile at 0° into an S-shaped profile at 180°. Because both an increase in the applied voltage and a decrease in the cell gap increase the electric field intensity, the backflow becomes large. The hybrid molecular configuration mode induces a larger backflow than that for the planar aligned mode. The backflow develops in two stages: an early stage with a microsecond time scale and a later stage with a millisecond time scale. The numerical predictions are in qualitative agreement with the measurements, but not quantitative agreement because our computation ignores the plate edge effect of surface tension.

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

    SciTech Connect

    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

    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.

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

    PubMed

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

    2012-11-01

    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

  13. The Behaviour of Laboratory Soil Electrical Resistivity Value under Basic Soil Properties Influences

    NASA Astrophysics Data System (ADS)

    Hazreek, Z. A. M.; Aziman, M.; Azhar, A. T. S.; Chitral, W. D.; Fauziah, A.; Rosli, S.

    2015-01-01

    Electrical resistivity method (ERM) was a popular indirect geophysical tools adopted in engineering, environmental and archaeological studies. In the past, results of the electrical resistivity value (ERV) were always subjected to a long discussion and debate among the related parties such as an engineers, geophysicists and geologists due to its lack of clarification and evidences in quantitative point of view. Most of the results produced in the past was always been justified using qualitative ways which difficult to be accept by certain parties. In order to reduce the knowledge gap between those parties, this study has performed a laboratory experiment of soil box resistivity test which supported by an additional basic geotechnical test as referred to particle size distribution test (d), moisture content test (w), density test (?bulk) and Atterberg limit test (LL, PL and PI). The test was performed to establish a series of electrical resistivity value with different quantity of water content for Clayey SILT and Silty SAND soil. It was found that the ERV of Silty SAND (600 - 7300 ?m) was higher than Clayey SILT (13 - 7700 ?m) due to the different quantity of basic soil properties value obtained from the basic geotechnical test. This study was successfully demonstrated that the fluctuation of ERV has greatly influenced by the variations of the soil physical properties (d, w, ?bulk, LL, PL and PI). Hence, the confidence level of ERV interpretation will be increasingly meaningful since it able to be proved by others parameter generated by laboratory direct test.

  14. Abnormal electrical resistivity in ?-TiAl thin films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Alford, T. L.; Gadre, K. S.; Kim, H. C.; Deevi, S. C.

    2003-07-01

    Thin films of ?-TiAl are being considered as a potential conductor and/or diffusion barrier for high temperature electronics because of their high melting points and high oxidation resistance. However, it is not possible to form pure ?-TiAl thin films by thermal annealing of Al/Ti bilayers. This study, however, demonstrates the formation of ?-TiAl thin films by dc magnetron sputtering of a compound target. X-ray diffractometry and Rutherford backscattering spectrometry analyses confirm the ?-TiAl phase formation, composition, and thermal stability in vacuum (up to 700 °C, 1 h) on SiO2. Four-point probe resistivity measurements in vacuum show an initial increase in the resistivity with temperature up to transition temperature for the ?-TiAl thin films. At higher temperatures a decrease in resistivity with additional heating (i.e., negative temperature coefficient of resistivity, TCR) is seen. The values of d?/dT are typically on the order of -0.32 ?? cm/°C between 200 and 550 °C. At the highest temperature, a minimum value of resistivity of ˜13 ?? cm is obtained; this value is about one half the value of bulk TiAl at room temperatures. The negative TCR, low resistivity values at high temperatures, and temperature stability are not typically seen in bulk TiAl. This abnormal electrical property is explained using a modified model for a thermally activated polaron-hopping mechanism.

  15. Using Electrical Resistivity Tomography for Constraining a Hydrogeological Model in a Data Sparse Region

    NASA Astrophysics Data System (ADS)

    Foster, S.; Allen, D. M.

    2013-12-01

    Geological and hydrogeological data are often spatially limited in mountainous regions. In these settings, geophysical techniques can be used to constrain hydrogeological models by providing insight into the hydrostratigraphy and the continuity of units in the subsurface. This study we used electrical resistivity tomography coupled with a priori geological data from residential water wells to improve the accuracy and confidence of a hydrogeological model. The study area is situated within the mountainous Cowichan watershed in British Columbia, Canada. Throughout the watershed, unconsolidated deposits of variable thickness overlie bedrock. Based on available water well information, at high elevation, sediment thickness is on the order of a few metres, but within the valley bottom, sediment thickness can be up to 300 m. The unconsolidated deposits are heterogeneous due to a complex depositional environment that was controlled by glacial advances and recessions, most notably during the Fraser Glaciation. Six electrical resistivity transects of various lengths spanning 135 to 830 metres were conducted in an area of the watershed that is particularly data poor. The electrical resistivity transects were strategically placed, first, to make use of available lithology information from existing water wells in order to constrain the geophysical interpretation, and second, to contribute data to areas that lack subsurface lithological records. Electrical resistivity was measured using a AGI SuperSting R1 system, and data were processed using robust inversion software to identify stark geophysical contacts. The technique successfully delineated zones of conductive and resistive units that have been interpreted as aquitards (clay and till formations), aquifers (water bearing sand and gravel lenses), and bedrock based on dielectric contrast. Available surficial geology and bedrock geology maps, coupled with residential well drilling records, further assisted in mapping the continuity of the hydrogeological units at a larger scale, and the results were digitized and integrated to construct a three dimensional hydrogeological model of the watershed.

  16. Continuous resistivity profiling data from Northport Harbor and Manhasset Bay, Long Island, New York

    USGS Publications Warehouse

    Cross, V.A.; Bratton, J.F.; Crusius, J.; Kroeger, K.D.; Worley, C.R.

    2012-01-01

    An investigation of coastal groundwater systems was performed along the North Shore of Long Island, New York, during May 2008 to constrain nutrient delivery to Northport Harbor and Manhasset Bay by delineating locations of likely groundwater discharge. The embayments are bounded by steep moraines and are underlain by thick, fine-grained sediments deposited in proglacial lakes during the last ice age. Beach sand and gravel overlie the glacial deposits along the coast. The continuous resistivity profiling (CRP) surveys that were conducted indicate the existence of low-salinity groundwater in shore-parallel bands, typically 25 to 50 meters wide, along the shorelines of both bays. Piezometer sampling and seepage meter deployments in intertidal and subtidal areas of the two bays confirmed the presence and discharge of brackish and low-salinity groundwater. The large tidal ranges (up to 3 meters) and the steep onshore topography and hydraulic gradients are important variables controlling coastal groundwater discharge in these areas.

  17. Studying electric field profiles in GaAs-based detector structures by Kelvin probe force microscopy

    NASA Astrophysics Data System (ADS)

    Vilisova, M. D.; Germogenov, V. P.; Kaztaev, O. Zh.; Novikov, V. A.; Ponomarev, I. V.; Titkov, A. N.

    2010-05-01

    The method of scanning Kelvin probe force microscopy has been used to study the electric field distribution in GaAs-based p +-?- n- n + detector structures. In the active layer volume, two maxima in the field strength profiles have been found, which are localized in the regions of p +-? and ?- n junctions. A volt-age drop on the ?- n junction expands the region of collection of nonequilibrium holes, thus increasing the charge collection efficiency for the absorption of ? photons with an energy of 59.5 keV.

  18. Application of top-down CD-SEM metrology in measuring and correlating profile with CD data in resist films with various thickness and sidewall profiles

    NASA Astrophysics Data System (ADS)

    Dixit, Sunit S.; Azordegan, Amir R.; Liu, Ying

    2000-06-01

    To have a more complete and clear picture for resist characterization, a second metric is needed to supplement the traditional linewidth data. A fast and non-destructive metrology system is desired to provide resist profile information. Electron scan and SEM image correlation capability will provide this second metric to effectively select the correct and precise process window. Monitoring for high electron line scan correlation values allows one to maintain a sharp sidewall profile of photoresist while supporting high aspect ratios. This is ideal for magneto- resistive (MR) and inductive thin film recording head coil plating and many other mission-critical applications. An automated top-down CD-SEM technique, capable of acquiring and analyzing electron waveform profiles of resist lines in addition to the traditional linewidth values is reported here. These measurements were made using a KLA-Tencor 8100 CD SEM, taking advantage of its new Pattern Quality Confirmation (pQC) feature. Process engineer using pQC can correlate signal intensity and images against stored templates, and then output the correlation scores. The technique has been applied to silicon wafers coated with various AZR photoresists, such as AZR 3300, AZR7200, AZR7500, and AZR7900, with thickness of 1 - 3 microns. Wafers were exposed using a Nikon I line stepper and then developed by AZR 300 metal ion free developer. Focus-Exposure dose-array fields were measured to investigate their profiles transformation as well as CD through and beyond their exposure latitude. Correlation scores were derived using aspect ratio of film thickness vs. CD size in each resist family. The study was extended by inspecting 'image correlation' values of high aspect ratio Contact Holes. Possibility of automating determination of open versus closed Contact Holes printed in these photoresists is also discussed. The goal of this study is to optimize determination of acceptable process window, by utilizing line and image correlation to compliment CD data.

  19. Electrical Resistance of Double-Wall Carbon Nanotubes with Determined Chiral Indices

    NASA Astrophysics Data System (ADS)

    Lin, Letian; Cui, Taoran; Qin, Lu-Chang; Washburn, Sean

    2011-03-01

    The properties of carbon nanotubes (CNT), especially single-wall nanotubes (SWNT) and double-wall nanotubes (DWNT), are profoundly sensitive to the atomic structure described by its chirality. CNTs connected to sub-micron electrodes were suspended for transmission electron microscope (TEM) study. We determined the chiral indices of each individual CNT via its nano beam electron diffraction patterns and measured its electrical resistance by the four-probe method at room temperature. We studied the factor of different combinations of semiconducting/metallic shells on the electrical characterizations of DWNTs. The electrical properties were compared between DWNTs and SWNTs and the result show that the electrical transport of a DWNT is dominated by the chiral indices of outer shell.

  20. Monitoring of olive oil mills' wastes using electrical resistivity tomography techniques

    NASA Astrophysics Data System (ADS)

    Simyrdanis, Kleanthis; Papadopoulos, Nikos; Kirkou, Stella; Sarris, Apostolos; Tsourlos, Panagiotis

    2014-08-01

    Olive oil mills' wastes (OOMW) are one of the byproducts of the oil production that can lead to serious environmental pollution when they are deposited in ponds dug on the ground surface. Electrical Resistivity Tomography (ERT) method can provide a valuable tool in order to monitor through time the physical flow of the wastes into the subsurface. ERT could potentially locate the electrical signature due to lower resistivity values resulting from the leakage of OOMW to the subsurface. For this purpose, two vertical boreholes were installed (12m depth, 9 m apart) in the vicinity of an existing pond which is filled with OOMW during the oil production period. The test site is situated in Saint Andreas village about 15km south of the city of Rethymno (Crete, Greece). Surface ERT measurements were collected along multiple lines in order to reconstruct the subsurface resistivity models. Data acquisition was performed with standard and optimized electrode configuration protocols. The monitoring survey includes the ERT data collection for a period of time. The study was initiated before the OOMW were deposited in the pond, so resistivity fluctuations are expected due to the flow of OOMW in the porous subsurface media through time. Preliminary results show the good correlation of the ERT images with the drilled geological formations and the identification of low resistivity subsurface zone that could be attributed to the flow of the wastes within the porous layers.

  1. ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY

    SciTech Connect

    MYERS DA; RUCKER DF; FINK JB; LOKE MH

    2009-12-16

    Highly industrialized areas pose challenges for surface electrical resistivity characterization due to metallic infrastructure. The infrastructure is typically more conductive than the desired targets and will mask the deeper subsurface information. These challenges may be minimized if steel-cased wells are used as long electrodes in the area near the target. We demonstrate a method of using long electrodes to electrically monitor a simulated leak from an underground storage tank with both synthetic examples and a field demonstration. The synthetic examples place a simple target of varying electrical properties beneath a very low resistivity layer. The layer is meant to replicate the effects of infrastructure. Both surface and long electrodes are tested on the synthetic domain. The leak demonstration for the field experiment is simulated by injecting a high conductivity fluid in a perforated well within the S tank farm at Hanford, and the resistivity measurements are made before and after the leak test. All data are processed in four dimensions, where a regularization procedure is applied in both the time and space domains. The synthetic test case shows that the long electrode ERM could detect relative changes in resistivity that are commensurate with the differing target properties. The surface electrodes, on the other hand, had a more difficult time matching the original target's footprint. The field results shows a lowered resistivity feature develop south of the injection site after cessation of the injections. The time lapsed regularization parameter has a strong influence on the differences in inverted resistivity between the pre and post injection datasets, but the interpretation of the target is consistent across all values of the parameter. The long electrode ERM method may provide a tool for near real-time monitoring of leaking underground storage tanks.

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

    SciTech Connect

    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

    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.

  3. Effect of Pressure on the Electrical Resistivity of Fe65(Ni0.84Mn0.16)35 Alloy

    NASA Astrophysics Data System (ADS)

    Hoshi, Kensuke; Oomi, Gendo; Mori, Nobuo

    1982-12-01

    The electrical resistivity of Fe65(Ni0.84Mn0.16)35 alloy is measured under high pressure up to 30 kbar from 4.2 K to 300 K. A resistance minimum is found near 25 K at atmospheric pressure. The temperature of the resistance minimum is appeared not to depend on pressure. Isothermal resistivity shows anomalous behaviors against pressure below 150 K. These results suggest the existence of a pressure induced magnetic phase transition at low temperature.

  4. Genotypic resistance profiles of HIV-2-treated patients in West Africa

    PubMed Central

    Charpentier, Charlotte; Eholié, Serge; Anglaret, Xavier; Bertine, Mélanie; Rouzioux, Christine; Avettand-Fenoël, Véronique; Messou, Eugène; Minga, Albert; Damond, Florence; Plantier, Jean-Christophe; Dabis, François; Peytavin, Gilles; Brun-Vézinet, Françoise; Ekouevi, Didier K.

    2014-01-01

    Objective To assess the virological response, genotypic resistance profiles, and antiretroviral plasma concentrations in HIV-2 antiretroviral-treated (antiretroviral therapy, ART) patients in Côte d‘Ivoire. Methods A cross-sectional survey was conducted among HIV-2 patients receiving ART. Plasma HIV-2 viral load was performed using the Agence Nationale de Recherche sur le SIDA et les hépatites virales (ANRS) assay. Protease and reverse transcriptase sequencing was performed using in-house methods and antiretroviral plasma concentrations were assessed using ultra performance liquid chromatography combined with tandem mass spectrometry. Results One hundred and forty-five HIV-2-treated patients were enrolled with a median CD4+ cell count of 360 cells/µl (interquartile range, IQR = 215–528). Median duration of ART was 4 years (IQR = 2–7) and 74% of patients displayed viral load less than 50 copies/ml. Median plasma HIV-2 RNA among patients with viral load more than 50 copies/ml was 3016 copies/ml (IQR = 436–5156). Most patients (84%) received a lopinavir/ritonavir-based regimen. HIV-2 resistance mutations to nucleoside reverse transcriptase inhibitors and protease inhibitors were detected in 21 of 25 (84%) and 20 of 29 (69%) samples, respectively. The most prevalent nucleoside reverse transcriptase inhibitor resistance mutations were M184I/V (90%), Q151M (24%), and S215F/Y (24%). The most prevalent protease inhibitor resistance mutations were V47A (60%) and I54M (30%). Median CD4+ cell counts were 434 cells/µl (292–573) and 204 cells/µl (122–281) in patients with viral load less than 50 copies/ml and those exhibiting virological failure (P < 0.0001), respectively. The proportions of patients with adequate antiretroviral plasma concentrations were 81 and 93% in patients displaying virological failure and in those with viral load less than 50 copies/ml, respectively (P = 0.046), suggesting good treatment adherence. Conclusion We observed adequate drug plasma concentrations and virological suppression in a high proportion of HIV-2-infected patients. However, in cases of virological failure, the limited HIV-2 therapeutic arsenal and cross-resistance dramatically reduced treatment options. PMID:24583671

  5. Dense resistivity and induced polarization profiling for a landfill restoration project at Härlöv, Southern Sweden.

    PubMed

    Leroux, Virginie; Dahlin, Torleif; Svensson, Mats

    2007-02-01

    A resistivity and time-domain induced polarization (IP) survey was conducted at a landfill site under restoration at Härlöv in Southern Sweden. The covering of the landfill had begun some years ago, without keeping precise records of the work done, as is usual in such procedures. The survey was conducted in two steps, on two adjacent areas. First, a number of geoelectrical sections were made on a partly covered area that had been investigated earlier by auger drilling, in order to assist restoration. Then, a second area that should have received its final cover was imaged, and some defects in the cover could be detected and repaired. The resistivity and time-domain IP results were consistent with the results of the geotechnical drillings, and they enabled quasi-continuous mapping along the profiles. Three-dimensional visualization showed the overall consistency of the two-dimensional lines, and helped to generate a global view of the site. In spite of some ambiguities, cover and waste could be distinguished in most cases. In particular, fine-grained cover materials could be clearly distinguished from other cover materials. PMID:17346007

  6. Identification of genes involved in imatinib resistance in CML: a gene-expression profiling approach.

    PubMed

    Villuendas, R; Steegmann, J L; Pollán, M; Tracey, L; Granda, A; Fernández-Ruiz, E; Casado, L F; Martínez, J; Martínez, P; Lombardía, L; Villalón, L; Odriozola, J; Piris, M A

    2006-06-01

    The use of the tyrosine kinase inhibitor imatinib, which blocks the enzymatic action of the BCR-ABL fusion protein, has represented a critical advance in chronic myeloid leukemia (CML) treatment. However, a subset of patients initially fails to respond to this treatment. Use of complementary DNA (cDNA) microarray expression profiling allows the identification of genes whose expression is associated with imatinib resistance. Thirty-two CML bone marrow samples, collected before imatinib treatment, were hybridized to a cDNA microarray containing 6500 cancer genes, and analyzed using bootstrap statistics. Patients refractory to interferon-alpha treatment were evaluated for cytogenetic and molecular responses for a minimum of 12 months. A set of 46 genes was differentially expressed in imatinib responders and non-responders. This set includes genes involved in cell adhesion (TNC and SCAM-1), drug metabolism (cyclooxygenase 1), protein tyrosine kinases and phosphatases (BTK and PTPN22). A six-gene prediction model was constructed, which was capable of distinguishing cytogenetic response with an accuracy of 80%. This study identifies a set of genes that may be involved in primary resistance to imatinib, suggesting BCR-ABL-independent mechanisms. PMID:16598311

  7. Multifractal analysis of vertical profiles of soil penetration resistance at the field scale

    NASA Astrophysics Data System (ADS)

    Siqueira, G. M.; Silva, E. F. F.; Montenegro, A. A. A.; Vidal Vázquez, E.; Paz-Ferreiro, J.

    2013-07-01

    Soil penetration resistance (PR) is widely used as an indirect indicator of soil strength. Soil PR is linked to basic soil properties and correlated to root growth and plant production, and as such it is extensively used as a practical tool for assessing soil compaction and to evaluate the effects of soil management. This study investigates how results from multifractal analysis can quantify key elements of depth-dependent soil PR profiles and how this information can be used at the field scale. We analysed multifractality of 50 PR vertical profiles, measured from 0 to 60 cm depth and randomly located on a 6.5 ha sugar cane field in northeastern Brazil. The scaling property of each profile was typified by singularity, and Rényi spectra estimated by the method of moments. The Hurst exponent was used to parameterize the autocorrelation of the vertical PR data sets. The singularity and Rènyi spectra showed that the vertical PR data sets exhibited a well-defined multifractal structure. Hurst exponent values were close to 1, ranging from 0.944 to 0.988, indicating strong persistence in PR variation with soil depth. Also, the Hurst exponent was negatively and significantly correlated to coefficient of variation (CV), skewness and maximum values of the depth-dependent PR. Multifractal analysis added valuable information to describe the spatial arrangement of depth-dependent penetrometer data sets, which was not taken into account by classical statistical indices. Multifractal parameters were mapped over the experimental field and compared with mean and maximum values of PR. Combination of spatial variability survey and multifractal analysis appear to be useful to manage soil compaction.

  8. Phenotypic and genotypic anti-microbial resistance profiles of campylobacters from untreated feedlot cattle and their environment.

    PubMed

    Minihan, D; Whyte, P; O'mahony, M; Cowley, D; O'halloran, F; Corcoran, D; Fanning, S; Collins, J D

    2006-05-01

    Anti-microbial resistance is an emerging public health issue. Farmed animals may act as reservoirs and potential sources of anti-microbial resistant Campylobacters. The aim of this study was to investigate the anti-microbial resistance profile of cattle and environmental Campylobacter isolates from normal untreated feedlot cattle, the role of the gyrA Thr-86-Ile mutation in ciprofloxacin-resistant Campylobacter jejuni isolates and the involvement of the tripartite CmeABC efflux system for multi-resistant C. jejuni isolates. The phenotypic anti-microbial resistance testing was carried out on 500 Campylobacter isolates (445 cattle isolates and 55 environmental isolates). In general, there was a higher level of anti-microbial resistance for the environmental isolates compared with the animal isolates, 45% of the animal isolates were resistant to one or more of the seven anti-microbials compared with 84% of the environmental isolates. The combined cattle and environmental Campylobacters had 34 (6.8%) isolates resistant to three or more of the seven anti-microbials tested on all isolates and 11 (2.2%) isolates were resistant to the seven anti-microbials. There was a substantial level of ciprofloxacin-resistant Campylobacters in both animal (8.5%) and environmental (21.8%) isolates. The gyrA Thr-86-Ile mutation was only present in five of 22 ciprofloxacin-resistant C. jejuni isolates investigated. No multi-drug-resistant associated mutation was detected in the CmeB or the CmeR regions investigated. In conclusion, our study observed a substantial level of Campylobacter anti-microbial resistance, highlighting the need for an active anti-microbial surveillance program for food animals in Ireland and the importance of the chosen sampling point can have on the findings of such a program. PMID:16629986

  9. Electric field penetration depth of myocardial surface catheters and the measurement of myocardial resistivity.

    PubMed

    Kottam, Anil; Pearce, John A

    2004-01-01

    The in vivo measurement of cardiac conductance in mice offers a method to generate an instantaneous left ventricular volume signal. In order to translate the measured conductance to volume, it is necessary to determine the resistivity of the myocardial tissue. This is done using tetrapolar surface conductance catheters, placed on the surface of the left ventricle. It is important to determine the depth of penetration of the electric field of this surface catheter to ensure that the electric field is confined within the myocardium and does not extend into the left ventricle blood volume. The depth of penetration is experimentally determined by a technique described by Foster et al. [2]. PMID:15133951

  10. Whole Blood Gene Expression Profiles in Insulin Resistant Latinos with the Metabolic Syndrome

    PubMed Central

    Tangen, Samantha E.; Tsinajinnie, Darwin; Nuñez, Martha; Shaibi, Gabriel Q.; Mandarino, Lawrence J.; Coletta, Dawn K.

    2013-01-01

    Although insulin resistance in skeletal muscle is well-characterized, the role of circulating whole blood in the metabolic syndrome phenotype is not well understood. We set out to test the hypothesis that genes involved in inflammation, insulin signaling and mitochondrial function would be altered in expression in the whole blood of individuals with metabolic syndrome. We further wanted to examine whether similar relationships that we have found previously in skeletal muscle exist in peripheral whole blood cells. All subjects (n=184) were Latino descent from the Arizona Insulin Resistance registry. Subjects were classified based on the metabolic syndrome phenotype according to the National Cholesterol Education Program’s Adult Treatment Panel III. Of the 184 Latino subjects in the study, 74 were classified with the metabolic syndrome and 110 were without. Whole blood gene expression profiling was performed using the Agilent 4x44K Whole Human Genome Microarray. Whole blood microarray analysis identified 1,432 probes that were altered in expression ?1.2 fold and P<0.05 after Benjamini-Hochberg in the metabolic syndrome subjects. KEGG pathway analysis revealed significant enrichment for pathways including ribosome, oxidative phosphorylation and MAPK signaling (all Benjamini-Hochberg P<0.05). Whole blood mRNA expression changes observed in the microarray data were confirmed by quantitative RT-PCR. Transcription factor binding motif enrichment analysis revealed E2F1, ELK1, NF-kappaB, STAT1 and STAT3 significantly enriched after Bonferroni correction (all P<0.05). The results of the present study demonstrate that whole blood is a useful tissue for studying the metabolic syndrome and its underlying insulin resistance although the relationship between blood and skeletal muscle differs. PMID:24358323

  11. Antibiotic resistance profiles to determine sources of fecal contamination in a rural Virginia watershed.

    PubMed

    Graves, Alexandria K; Hagedorn, Charles; Teetor, Alison; Mahal, Michelle; Booth, Amy M; Reneau, Raymond B

    2002-01-01

    Antibiotic resistance analysis (ARA) was used to determine if enterococci of human origin were present in a stream (Spout Run) that passes through a rural nonsewered community (Millwood, VA). Millwood consists of 82 homes, all served by individual septic systems, and Spout Run drains a 5,800-ha karst topography watershed that contains large populations of livestock and wildlife. Periodic monitoring by state regulatory officials had resulted in Spout Run being placed on the Virginia impaired stream list and Millwood being categorized as an at-risk community. Stream samples were collected monthly and analyzed for fecal coliforms and enterococci (May 1999-May 2000); ARA was performed on enterococci stream isolates on a quarterly basis. All 117 stream samples were positive for fecal coliforms, and 32% exceeded the Virginia recreational water standard (1,000 fecal coliforms/100 mL). A library of 1,174 known source Enterococcus isolate antibiotic resistance profiles was constructed, and yielded correct classification rates of 94.6% for 203 human isolates, 93.7% for 734 livestock isolates, and 87.8% for 237 wildlife isolates. Antibiotic resistance analysis of 2,012 enterococcal isolates recovered from stream samples indicated isolates of human origin appeared throughout the stream as it passed through Millwood, with a yearly average of approximately 10% human, 40% wildlife, and 50% livestock. There were no human origin isolates in samples collected upstream from Millwood, and the percent human origin isolates declined downstream from Millwood. While a human signature was found in Spout Run, it was small compared with the proportion of isolates from livestock and wildlife. PMID:12175050

  12. 3-Dimensional Mapping of Electrical Resistivity and Geological Data with Combination of CPTe Data for understanding the Fluid Transport Processes

    NASA Astrophysics Data System (ADS)

    Kanli, A. I.; Nyari, Z.; Stickel, J.; Tillmann, A.

    2012-12-01

    To understand the hydrogeological process and spatial distribution of contamination, there are several conventional methods which are gathered under two main branches that are invasive and non-invasive techniques. Standard Penetration Test and Conic Penetration Test techniques are called as classical borehole techniques and they are accepted among the invasive or less-invasive techniques. On the other hand, electrical and electromagnetic based Electrical Resistivity Tomography and Ground Penetrating Radar, most widely used techniques in imaging the subsurface in the last decade, are called as non-invasive geophysical methods. 3D electrical resistivity distribution provides information about water flow and changes in electrical resistivity of the pore fluid. Therefore, to assist in understanding and modeling of the fluid transport process, 3D spatial distribution of the electrical resistivity data with the corresponded 3D geological section were mapped and interpreted in the test site located in western Germany.

  13. Changes in gene expression profile in two multidrug resistant cell lines derived from a same drug sensitive cell line.

    PubMed

    Moreira, Miguel Angelo Martins; Bagni, Carolina; de Pinho, Marcos Barcelos; Mac-Cormick, Thaís Messias; dos Santos Mota, Mateus; Pinto-Silva, Flávio Eduardo; Daflon-Yunes, Nathalia; Rumjanek, Vivian Mary

    2014-08-01

    Resistance to chemotherapy is one of the most relevant aspects of treatment failure in cancer. Cell lines are used as models to study resistance. We analyzed the transcriptional profile of two multidrug resistant (MDR) cell lines (Lucena 1 and FEPS) derived from the same drug-sensitive cell K562. Microarray data identified 130 differentially expressed genes (DEG) between K562 vs. Lucena 1, 1932 between K562 vs. FEPS, and 1211 between Lucena 1 versus FEPS. The NOTCH pathway was affected in FEPS with overexpression of NOTCH2 and HEY1. The highly overexpressed gene in MDR cell lines was ABCB1, and both presented the ABCB1 promoter unmethylated. PMID:24996974

  14. Electron Beam Lithography Double Step Exposure Technique for Fabrication of Mushroom-Like Profile in Bilayer Resist System

    NASA Astrophysics Data System (ADS)

    Kornelia, Indykiewicz; Bogdan, Paszkiewicz; Tomasz, Szyma?ski; Regina, Paszkiewicz

    2015-01-01

    The Hi/Lo bilayer resist system exposure in e-beam lithography (EBL) process, intended for mushroom-like profile fabrication, was studied. Different exposure parameters and theirs influence on the resist layers were simulated in CASINO software and the obtained results were compared with the experimental data. The AFM technique was used for the estimation of the e-beam penetration depth in the resist stack. Performed numerical and experimental results allow us to establish the useful ranges of the exposure parameters.

  15. L- and Corner-arryas for 3D electric resistivity tomography: An alternative for geophysical surveys in urban zones

    NASA Astrophysics Data System (ADS)

    Chavez Segura, R. E.; Tejero-Andrade, A.; Delgado-Solorzano, C.; Cifuentes-Nava, G.; Hernández-Quintero, E.

    2011-12-01

    3D Electric Resitivity Tomography methods carried out on heavily urbanized areas become a difficult task, since buildings, houses or other type of obstacles do not allow parallel ERT arrays to be deployed. Therefore, insufficient information from the subsoil could be obtained. The present paper presents two new techniques, which allow acquiring information beneath a construction by simply surrounding the building or buildings to be studied by a series of ERT profiles. Apparent resistivities are obtained from L-shaped profiles, where alternations between current and potential electrodes along this array are carried out in an automatic way. Four L-arrays and four Corner-arrays are needed to cover the subsurface beneath the studied area. A field test was carried out on a small University of Mexico main Campus garden, where trees and other anthropogenic structures were the so called 'obstacles'. Geophysical work was performed employing parallel arrays (traditional methodology) and compared with this new method presented. Results show that the new method has a poor resolution towards the central portion of the area, mainly from anomalies produced by shallow structures as compared with the traditional grid method. However, the L- and Corner- arrays are more sensitive to anomalies produced by deeper objects, which cannot be observed in the traditional method. The final goal is to apply this method to study habitational complexes built on top of the ancient lake of Mexico City, where buildings are in constant risk due to fracturing and subsidence.

  16. Electrical resistance tomography during gas injection at the Savannah River Site

    SciTech Connect

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

    1993-05-01

    Electrical resistance tomography (ERT) is used to monitor some of the in situ remediation processes being evaluated for removal of volatile organic compounds from subsurface water and soil at the Integrated Demonstration for VOC`s in Soils and Groundwater at Non Arid Sites, the Savannah River Site, near Aiken, South Carolina. Air was injected in the saturated zone and the intrained air was tomographically imaged by its effects on the formation electrical resistivity. The authors found that the flow paths are confined to a complex three dimensional network of channels, some of which extend as far as 30 m from the injection well. They conclude, based on these results, that the shape and extent of the air plume are controlled by spatial variations in the local gas permeability. These channels are somewhat unstable over a period of months and new channels appear to form with time.

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

    PubMed

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

    2008-09-01

    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

  18. Electrical resistivity and TDR methods for soil moisture estimation in central Italy test-sites

    NASA Astrophysics Data System (ADS)

    Calamita, G.; Brocca, L.; Perrone, A.; Piscitelli, S.; Lapenna, V.; Melone, F.; Moramarco, T.

    2012-08-01

    SummaryIn this study, the feasibility of the resistivity method for the study of the spatial and temporal soil moisture variations in the Vallaccia catchment (central Italy), covering an area of about 56 km2, was investigated. Correlation and regression analyses were performed over a 1 year data set of simultaneous soil electrical resistivity and soil moisture measurements, acquired in eight different sites with a Resistivimeter Syscal Junior and a portable Time Domain Reflectometer (TDR), respectively. Measurements acquired in-time by continuous Frequency Domain Reflectometer (FDR) sensors were also used and compared with simultaneous resistivity measurements. The statistical analyses were conducted not only for the whole data set, but also separately for each sampling day, for each sampling site and considering spatially averaged data. Results showed a good correlation between resistivity and soil moisture measurements, revealing the capability of resistivity measurements to infer soil moisture spatial and temporal variability with a root mean square error equal, on average, to 4.4% vol/vol. In comparison with TDR, the resistivity method gives information integrated on a greater volume of soil and the measurements are easier and quicker to be carried out. Therefore, this method can be considered as an alternative tool to be employed for qualitative and quantitative soil moisture monitoring in small to medium catchments.

  19. Laboratory measurements of basalts electrical resistivity under deep oceanic crustal conditions

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

  20. Electrical Resistance of Double-Wall Carbon Nanotubes with Determined Chiral Indices

    Microsoft Academic Search

    Letian Lin; Taoran Cui; Lu-Chang Qin; Sean Washburn

    2011-01-01

    The properties of carbon nanotubes (CNT), especially single-wall nanotubes (SWNT) and double-wall nanotubes (DWNT), are profoundly sensitive to the atomic structure described by its chirality. CNTs connected to sub-micron electrodes were suspended for transmission electron microscope (TEM) study. We determined the chiral indices of each individual CNT via its nano beam electron diffraction patterns and measured its electrical resistance by

  1. Experimental Study on the Dynamic Resistance of the Electric-Bag Complex Dust Collector

    Microsoft Academic Search

    Zongbing Liu; Ying Liu; Ning Mao; Deqiang Chang; Jingxian Liu; Xi Sun

    2010-01-01

    The Electric-Bag Complex Dust Collector (EBCDC) is being widely used for dust removal of flue gas from the coal-fired power station boiler. Electrostatic precipitator (ESP), as a pre-collector, has a certain effect on the post-baghouse. In this paper, systematic experiments are done to study the effect of the filtration resistance, the formation of dust cake and the cleaning process of

  2. Correlation of the electrical resistivity of fluid-saturated cores with water saturation and shaliness

    E-print Network

    Desai, Bhupendra Chhotabhai

    1966-01-01

    Professor of Petro- leum Engineering. As chairman of the author's graduate committee, he was ever available for consultation and offered many constructive criticisms. Special thanks are extended to the author's com- mittee members, Mr. R. L. Whiting... in Reservoir Rock as a Factor in Electrical Log Interpretation, " Journal of Petro- leum Technology (February, 1950), p. 120. 9. De Witte, L. : "The Relation between Resistivities and Fluid Contents of Porous Rocks, " Oil and Gas Journal (August 24, 1950...

  3. Comparing Time Domain Reflectometry and Electrical Resistivity Tomography Measurements for Estimating Soil Water Distribution

    Microsoft Academic Search

    Christian Hauck; Alexander Scheuermann

    Two different methods to determine the spatial distribution of soil water were tested and compared on a full-scale dike model. TDR-measurements of the spatially distributed water content along transmission lines were compared with electrical resistivity tomography (ERT) measurements along the same cross-section. In contrast to the TDR method, ERT is a non-invasive method and does not require the perturbation of

  4. A high pressure-high temperature cell for electrical resistivity studies

    Microsoft Academic Search

    Mohammad Yousuf; P Ch Sahu; K Govinda Rajan

    1985-01-01

    A high pressure-high temperature cell which permitsin-situ pressure and temperature calibration is described. The cell is in an opposed anvil configuaration, and houses two samples\\u000a with four probes each along with a miniature furnace and a thermocouple. The pressure and temperature capability of the cell\\u000a are 100 kbar and 1000°C respectively. This cell was developed to study the electrical resistivity

  5. Resolving Large Preglacial Valleys Buried by Glacial Sediment Using Electric Resistivity Imaging (ERI)

    Microsoft Academic Search

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

    2004-01-01

    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

  6. Characterization of Quaternary faults by electric resistivity tomography in the Andean Precordillera of Western Argentina

    Microsoft Academic Search

    Sabrina Y. Fazzito; Augusto E. Rapalini; José M. Cortés; Carla M. Terrizzano

    2009-01-01

    Structural and geomorphic surface observations are frequently insufficient for a proper geometric and kinematic characterization of Quaternary faults. In order to improve the geological knowledge of three Quaternary faults in the Precordillera of western Argentina (30°46? S–32°24? S, 69°07? W–69°15? W), a shallow 2D Electrical Resistivity Tomography (ERT) survey was performed along seven short cross-sections, perpendicular to the fault traces.

  7. Correlation between electrical resistance and microstructure in gold wirebonds on aluminum films

    Microsoft Academic Search

    LISA MAIOCCO; DONNA SMYERS; PAUL R. MUNROE; IAN BAKER

    1990-01-01

    Gold ball bonds attached to either pure Al films or Al films with Cu and Si additions were annealed at temperatures in the range 77-277°C for periods of up to 3000 h. Electrical resistance of the bonds was measured to within ±1 m? using a manual four-probe arrangement with an applied current of up to 100 mA. Nonlinear multiple regression

  8. First-Principles Study of Electrical Resistivity in Co$_{2}$ MnSi Compounds

    Microsoft Academic Search

    Y. Kota; A. Sakuma

    2011-01-01

    Theoretical study of the electrical resistivity is performed for Heusler compounds Co MnSi with atomic disorder by using the firstprinciples techniques based on the tight-binding linear muffin-tin orbital method and Kubo?Greenwood formula. Experimentally, it is so difficult to control the degree of the ordering of the Heusler compounds precisely that their conduction property have not been clarified enough. In this

  9. A method to investigate the electron scattering characteristics of ultrathin metallic films by in situ electrical resistance measurements

    SciTech Connect

    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

    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.

  10. Monitoring active layer thaw and freeze-back in four different periglacial landforms in Svalbard using Electrical Resistivity Tomography (ERT)

    NASA Astrophysics Data System (ADS)

    Juliussen, H.; Oswald, A.; Watanabe, T.; Christiansen, H. H.; Matsuoka, N.

    2012-04-01

    Thawing and freezing of the active layer has an important impact on the underlying permafrost through latent heat effects and changes in effective thermal conductivity and mechanisms of heat transport. Information on the active layer freeze/thaw dynamics is therefore important to understand the permafrost response to climate variability. In addition, active layer deepening may be an early sign of permafrost degradation, making monitoring programs such as the CALM network important. Active layer depths are traditionally measured by mechanical probing in fine-grained sediments or by vertical arrays of ground temperature sensors. The first technique prevents measurements to be made in stony sediments, while the latter technique gives only a point value of the active layer depth. In this study we have tested Electrical Resistivity Tomography (ERT) as a tool to measure and monitor active layer depth and freeze/thaw dynamics. The electrical resistivity of the ground is largely dependent on the unfrozen water content, making resistivity monitoring a potentially valuable tool to delineate freeze and thaw extent, and patterns in soil moisture. The results presented here are part of the IPY 2007-2009 research project 'Permafrost Observatory Project: A Contribution to the Thermal State of Permafrost in Norway and Svalbard' (TSP NORWAY) and the IPA periglacial working group project on 'High-Resolution Periglacial Climate Indicators'. Electrode arrays were installed permanently in four different periglacial landforms in the Adventdalen valley area in central Svalbard; a solifluction slope in May 2007, a loess terrace (the UNISCALM site) in September 2007, and a mudboil site and ice-wedge site in June 2009 (Watanabe et al., submitted). The arrays were 16m long, giving maximum profile depths of 2m, and electrodes were installed with 0.2m spacing. Measurements were made with irregular but approximately two- to four-week time intervals, depending on weather conditions and instrument availability. Data are available until autumn 2009 for all sites, and until autumn 2010 for the mudboil and ice-wedge sites. Ground temperature and soil moisture is monitored at all four sites, and mechanical probing of thaw depth progression was performed along with the resistivity measurements for parts of the period. The apparent resistivity raw data error is low in the summer, but in the wintertime 40 to 50% of the data was excluded in the worst cases. The errors are higher in the dry loess site also in the summer, compared to the other three relatively wet sites. After inverting the raw data to give subsurface models of the specific resistivity, depth of investigation mapping was made to identify model areas that were not well constrained by the data. The models show good reliability except at the model edges, in some cases of steep resistivity gradients and at local resistivity extremes. Preliminary results of this study have been presented (Juliussen et al 2010, Oswald 2010), but here the aim is to (1) quantify the accuracy of ERT-based thaw depth estimates as compared to the probed depths, and (2) to analyze the resistivity values with respect to soil moisture and temperature data and ground ice content obtained from coring.

  11. Petrologically-based Electrical Profiles vs. Geophysical Observations through the Upper Mantle (Invited)

    NASA Astrophysics Data System (ADS)

    Gaillard, F.; Massuyeau, M.; Sifre, D.; Tarits, P.

    2013-12-01

    Mineralogical transformations in the up-welling mantle play a critical role on the dynamics of mass and heat transfers at mid-ocean-ridgeS. The melting event producing ridge basalts occur at 60 km depth below the ridge axis, but because of small amounts of H2O and CO2 in the source region of MOR-basalts, incipient melting can initiate at much greater depth. Such incipient melts concentrate incompatible elements, and are particularly rich in volatile species. These juices evolve from carbonatites, carbonated basalts, to CO2-H2O-rich basalts as recently exposed by petrological surveys; the passage from carbonate to silicate melts is a complex pathway that is strongly non-linear. This picture has recently been complicated further by studies showing that oxygen increasingly partitions into garnet as pressure increases; this implies that incipient melting may be prevented at depth exceeding 200 km because not enough oxygen is available in the system to stabilize carbonate melts. The aim of this work is twofold: - We modelled the complex pathway of mantle melting in presence of C-O-H volatiles by adjusting the thermodynamic properties of mixing in the multi-component C-O-H-melt system. This allows us to calculate the change in melt composition vs. depth following any sortS of adiabat. - We modelled the continuous change in electrical properties from carbonatites, carbonated basalts, to CO2-H2O-rich basalts. We then successfully converted this petrological evolution along a ridge adiabat into electrical conductivity vs. depth signal. The discussion that follows is about comparison of this petrologically-based conductivity profile with the recent profiles obtained by inversion of the long-period electromagnetic signals from the East-Pacific-Rise. These geophysically-based profiles reveal the electrical conductivity structure down to 400 km depth and they show some intriguing highly conductive sections. We will discuss heterogeneity in electrical conductivity of the upper mantle underneath the ridge in terms of melting processes. Our prime conclusion is that the redox melting process, universally predicted by petrological models, might not be universal and that incipient melting can extend down to the transition zone.

  12. Electrical resistivity measurements on manganese oxides with layer and tunnel structures: Birnessites, todorokites, and cryptomelanes

    SciTech Connect

    De Guzman, R.N.; Awaluddin, A.; Shen, Y.F. [and others

    1995-07-01

    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.

  13. Hydrostratigraphy and hydrogeology of the western part of Maira area, Khyber Pakhtunkhwa, Pakistan: a case study by using electrical resistivity.

    PubMed

    Farid, Asam; Jadoon, Khanzaib; Akhter, Gulraiz; Iqbal, Muhammad Asim

    2013-03-01

    Hydrostratigraphy and hydrogeology of the Maira vicinity is important for the characterization of aquifer system and developing numerical groundwater flow models to predict the future availability of the water resource. Conventionally, the aquifer parameters are obtained by the analysis of pumping tests data which provide limited spatial information and turn out to be costly and time consuming. Vertical electrical soundings and pump testing of boreholes were conducted to delineate the aquifer system at the western part of the Maira area, Khyber Pakhtun Khwa, Pakistan. Aquifer lithology in the eastern part of the study area is dominated by coarse sand and gravel whereas the western part is characterized by fine sand. An attempt has been made to estimate the hydraulic conductivity of the aquifer system by establishing a relationship between the pumping test results and vertical electrical soundings by using regression technique. The relationship is applied to the area along the resistivity profiles where boreholes are not drilled. Our findings show a good match between pumped hydraulic conductivity and estimated hydraulic conductivity. In case of sparse borehole data, regression technique is useful in estimating hydraulic properties for aquifers with varying lithology. PMID:22736209

  14. Direct-push hydrostratigraphic profiling: Coupling electrical logging and slug tests

    USGS Publications Warehouse

    Sellwood, S.M.; Healey, J.M.; Birk, S.; Butler, J.J., Jr.

    2005-01-01

    Spatial variations in hydraulic conductivity (K) can significantly affect the transport of contaminants in ground water. Conventional field methods, however, rarely provide a description of these variations at the level of detail necessary for reliable transport predictions and effective remediation designs. A direct-push (DP) method, hydrostratigraphic profiling, has been developed to characterize the spatial variability of both electrical conductivity (EC) and hydraulic conductivity in unconsolidated formations in a cost-effective manner. This method couples a dual-rod approach for performing slug tests in DP equipment with high-resolution EC logging. The method was evaluated at an extensively studied site in the Kansas River floodplain. A series of profiles was performed on a surface grid, resulting in a detailed depiction of the three-dimensional distribution of EC and K. Good agreement was found between K estimates obtained from this approach and those obtained using other methods. The results of the field evaluation indicate that DP hydrostratigraphic profiling is a promising method for obtaining detailed information about spatial variations in subsurface properties without the need for permanent wells.

  15. Microgravity conditions and electrical resistivity of liquid alloys with critical mixing

    SciTech Connect

    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

    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.

  16. Thermal Expansion, Electrical Resistivity, and Spreading Area of Sn-Zn-In Alloys

    NASA Astrophysics Data System (ADS)

    Gancarz, Tomasz; Fima, Przemys?aw; Pstru?, Janusz

    2014-05-01

    Thermal expansion and electrical resistivity of alloys based on Sn-Zn eutectic with 0.5, 1.0, 1.5, and 4.0 wt.% additions of In were studied. Thermal expansion measurements were performed using thermomechanical analysis tester over 223-373 K temperature range. Electrical resistivity measurements were performed with four-probe method over 298-423 K temperature range. The electrical resistivity of alloys increases linearly with temperature and concentration of In; also coefficient of thermal expansion of the studied alloys increases with In concentration. Scanning electron microscopy revealed simple eutectic microstructure with In dissolved in Sn-rich matrix. The results obtained were compared with the available literature data. Spreading tests on Cu of Sn-8.8Zn alloys with 0.5, 1.0, and 1.5 at.% of In were performed. Wetting tests were performed at 250 °C, by sessile drop method, by means of flux, and wetting times were 3, 8, 15, 30, and 60 min. In general, no clear effect of wetting time on spreading was observed.

  17. Influence of salinity and moisture content in electrical resistivity tomography readings in geomaterials used in construction

    NASA Astrophysics Data System (ADS)

    Gomez-Heras, Miguel; Fort, Rafael; Garcia Morales, Soledad

    2014-05-01

    Wetness and salts are among the main agents hindering the performance of any porous building material. There are a number of techniques based on electrical properties for the detection of these agents in buildings, such as portable moisture meters and electric resistivity tomography (ERT). These methods are used to locate wet areas based on the lower electrical resistivity wet materials have in relation to dry ones. However, as both moisture and salts contribute to low resistivity readings, the ERT readings may have a degree of uncertainty. This research aims to study the contribution of salinity and moisture content on the readings of ERT by testing laminated gypsum boards in the laboratory with solutions with different compositions (i.e. sodium chloride, magnesium sulphate and a mixture of both) and concentrations of salts. An industrial product, such as the laminated gypsum board, was chosen to minimize the effects that heterogeneities in composition and physical properties could have in the ERT readings and facilitate the interpretation of the wetness/salt content difference. Gypsum board was soaked with a fixed amount of the chosen solutions and several ERT transects were performed with a GeoTom device (Geolog2000) while drying. Results show the influence salinity of solutions have in drying process, and how the salt content remaining within the pores of geomaterials impact on ERT results. Research funded by Geomateriales (S2009/MAT-16) and CEI Moncloa (UPM, UCM, CSIC) through a PICATA contract and the equipment from RedLAbPAt Network

  18. Electrical Resistivity Investigation of Gas Hydrate Distribution in Mississippi Canyon Block 118, Gulf of Mexico

    SciTech Connect

    Dunbar, John

    2012-12-31

    Electrical methods offer a geophysical approach for determining the sub-bottom distribution of hydrate in deep marine environments. Methane hydrate is essentially non-conductive. Hence, sediments containing hydrate are more resistive than sediments without hydrates. To date, the controlled source electromagnetic (CSEM) method has been used in marine hydrates studies. This project evaluated an alternative electrical method, direct current resistivity (DCR), for detecting marine hydrates. DCR involves the injection of direct current between two source electrodes and the simultaneous measurement of the electric potential (voltage) between multiple receiver electrodes. The DCR method provides subsurface information comparable to that produced by the CSEM method, but with less sophisticated instrumentation. Because the receivers are simple electrodes, large numbers can be deployed to achieve higher spatial resolution. In this project a prototype seafloor DCR system was developed and used to conduct a reconnaissance survey at a site of known hydrate occurrence in Mississippi Canyon Block 118. The resulting images of sub-bottom resistivities indicate that high-concentration hydrates at the site occur only in the upper 50 m, where deep-seated faults intersect the seafloor. Overall, there was evidence for much less hydrate at the site than previously thought based on available seismic and CSEM data alone.

  19. Electrical resistivity and thermoelectric power of polyacrylonitrile-cuprous sulfide composite fibers

    SciTech Connect

    Kawamura, K.; Ikeda, M.; Tsuzuku, T.

    1985-01-01

    Electrical resistance and thermoelectricity of six specimens of acrylonitrile-cuprous sulfide composite fibers have been investigated. The concentration of cuprous sulfide used as dopant ranges stepwise from 1.82 up to 7.02 wt.%, and a minimum of the room-temperature resistivity is indicated to be 5 x 10/sup -2/ omega cm at about 4 wt.%. Although an anomaly similar to that of the semiconductor-metal transition is observed at 330 + 20 K for all samples, the resistivity variation with temperature below 300 K is so small as to imply that the electronic system is totally degenerate. The thermoelectric power is positive except for two heavily-doped fibers below 50 K, and increases linearly with increasing temperature up to 250 K. Results are discussed with reference to the nature of cuprous sulfides and of well-defined one-dimensional conductors. 5 references, 7 figures, 1 table.

  20. Test facility for simultaneous measurement of electrical and thermal contact resistance

    NASA Astrophysics Data System (ADS)

    Misra, Prashant; Nagaraju, J.

    2004-08-01

    A test setup has been developed for simultaneously evaluating the electrical contact resistance (ECR) and thermal contact resistance/conductance (TCR/TCC) across meta-metal contacts at different contact pressures and mean interface temperatures. ECR and TCC across brass-brass contacts in vacuum have been measured simultaneously at different contact pressures and mean interface temperatures. The results obtained are found to be in agreement with the theoretical models available in the literature for ECR and TCC, independently from each other. The maximum absolute uncertainties in the measurement of ECR and TCC with the present setup are estimated to be ±0.003% and ±4.4%, respectively. Apart from contact resistance measurements, the setup is also used to determine thermal conductivity of unknown materials viz., oxygen-free high-conductivity copper and brass, at different temperatures.

  1. Changes in gene expression profiles as they relate to the adult plant leaf rust resistance in the wheat cv. Toropi

    PubMed Central

    Casassola, Alice; Brammer, Sandra P.; Chaves, Márcia S.; Martinelli, José A.; Stefanato, Francesca; Boyd, Lesley A.

    2015-01-01

    Leaf rust, caused by the foliar pathogen Puccinia triticina is a major disease of wheat in the southern region of Brazil and invariably impacts on production, being responsible for high yield losses. The Brazilian wheat cultivar Toropi has proven, durable adult plant resistance (APR) to leaf rust, which uniquely shows a pre-haustorial resistance phenotype. In this study we aimed to understand the interaction between P. triticina and the pre-haustorial APR in Toropi by quantitatively evaluating the temporal transcription profiles of selected genes known to be related to infection and defense in wheat. The expression profiles of 15 selected genes varied over time, grouping into six expression profile groups. The expression profiles indicated the induction of classical defence pathways in response to pathogen development, but also the potential modification of Toropi's cellular status for the benefit of the pathogen. Classical defence genes, including peroxidases, ?-1,3-glucanases and an endochitinase were expressed both early (pre-haustorial) and late (post-haustorial) over the 72 h infection time course, while induction of transcription of other infection-related genes with a potential role in defence, although variable was maintained through-out. These genes directly or indirectly had a role in plant lignification, oxidative stress, the regulation of energy supply, water and lipid transport, and cell cycle regulation. The early induction of transcription of defence-related genes supports the pre-haustorial resistance phenotype in Toropi, providing a valuable source of genes controlling leaf rust resistance for wheat breeding.

  2. GEOGRAPHICAL VARIATION IN ANTIBIOTIC RESISTANCE PROFILES OF ESCHERICHIA COLI ISOLATED FROM SWINE, POULTRY, BEEF AND DAIRY CATTLE FARMS IN FLORIDA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli multiple antibiotic resistance (MAR) profiles have been studied to identify sources of fecal pollution. However, research is needed to understand the geographical limitations in applying MAR. More than 2000 E. coli were isolated from swine, poultry, beef and dairy farms in south ...

  3. Transcriptional profiling reveals elevated CO2 and elevated O3 alter resistance of soybean (Glycine max) to Japanese

    E-print Network

    DeLucia, Evan H.

    Transcriptional profiling reveals elevated CO2 and elevated O3 alter resistance of soybean (Glycine the interactions between plants and insects. Using microarray analysis of field-grown soybean (Glycine max), we found that the number of transcripts in the leaves affected by herbivory by Japanese beetles (Popillia

  4. Association of multiple-antibiotic-resistance profiles with point and nonpoint sources of Escherichia coli in Apalachicola Bay.

    PubMed Central

    Parveen, S; Murphree, R L; Edmiston, L; Kaspar, C W; Portier, K M; Tamplin, M L

    1997-01-01

    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

  5. MULTIPLE ANTIBIOTIC RESISTANCE PROFILES OF ESCHERICHIA COLI ISOLATED FROM SWINE, POULTRY, BEEF AND CATTLE FARMS IN FLORIDA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multiple antibiotic resistance (MAR) profiles have been studied in Escherichia coli in an effort to predict specific sources of fecal pollution. However, research is needed to understand the geographical limitations in applying MAR to defined pollution sources. More than 2000 E. coli were isolated ...

  6. Microstructures, mechanical properties, and electrical resistivity of rapidly quenched Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Naohara, T.; Inoue, A.; Minemura, T.; Masumoto, T.; Kumada, K.

    1982-03-01

    By the rapid quenching technique, ductile supersaturated ferrite solid solution with high hardness and strength as well as unusual electrical properties has been found in Fe-Cr-Al ternary system. This formation range is limited to less than about 35 at. pct Cr and 23 at. pct Al. The ferrite phase has fine grains of about 10 ?m in diameter. Their hardness, yield strength, and tensile fracture strength increase with increase in the amounts of chromium and aluminum, and the highest values reach about 290 DPN, 720 MPa, and 740 MPa. These alloys are so ductile that no cracks are observed even after closely contacted bending test. The good strength and ductility remain almost unchanged on tempering for one hour until heated to about 923 K where a large amount of Cr2Al compound begins to precipitate preferentially along the grain boundaries of the ferrite phase. The room-temperature resistivity increases with increasing chromium and aluminum contents and reaches as high as 1.86 ? ? m for Fe50Cr30Al20 alloy. Also, the temperature coefficient of resistivity in the temperature range between room temperature and 773 K decreases with increasing chromium and aluminum contents and becomes zero in the vicinity of 20 to 30 at. pct Cr and 15 at. pct Al. Thus, the present alloys may be attractive as fine gauge high-resistance and/or standard-resistance wires and plates because of the unusual electrical properties combined with high strength and good ductility.

  7. Geophysical evaluation of solute plume spatial moments using an adaptive POD algorithm for electrical resistivity imaging

    NASA Astrophysics Data System (ADS)

    Oware, E. K.; Moysey, S. M. J.

    2014-09-01

    We investigate the potential for characterizing spatial moments of subsurface solute plumes from surface-based electrical resistivity images produced within a Proper Orthogonal Decomposition (POD) inversion framework. The existing POD algorithm is improved here to allow for adaptive conditioning of the POD training images on resistivity measurements. The efficacy of the suggested technique is evaluated with two hypothetical transport scenarios: synthetic #1 is based on the case where the target plume and POD training images follow the same (unimodal) plume morphology, whereas a second source location in synthetic #2 makes the target plume bimodal and inconsistent with the POD training images. The resistivity imaging results indicate that the adaptive algorithm efficiently and robustly updates the POD training images to obtain good quality resistivity images of the target plumes, both in the presence of data noise and when conceptual model inaccuracies exist in the training simulations. Spatial moments of the solute plumes recovered from the resistivity images are also favorable, with relative mass recovery errors in the range of 0.6-4.4%, center of mass errors in the range of 0.6-9.6%, and spatial variance errors in the range of 3.4-45% for cases where the voltage data had 0-10% noise. These results are consistent with or improved upon those reported in the literature. Comparison of the resistivity-based moment estimates to those obtained from direct concentration sampling suggests that for cases with good quality resistivity data (i.e., <3% noise), the imaging results provide more accurate moments until 6-10 multi-level sampling wells are installed. While the specific number of wells will depend on the actual field scenario, we suggest that this finding illustrates the general value of POD-based resistivity imaging techniques for non-invasively estimating the spatial moments of a solute plume.

  8. Microbiota and anthropic interference on antimicrobial resistance profile of bacteria isolated from Brazilian maned-wolf (Chrysocyon brachyurus)

    PubMed Central

    Vieira-da-Motta, Olney; Eckhardt-de-Pontes, Luiz Antonio; Petrucci, Melissa Paes; dos Santos, Israel Pereira; da Cunha, Isabel Candia Nunes; Morato, Ronaldo Gonçalves

    2013-01-01

    Both the study of Brazilian wild mammal fauna and the conditions that foster the preservation of endangered species, such as Brazilian Maned-wolf (Chrysocyon brachyurus), in wild life are of extreme importance. In order to study the resistance profile of microbiota bacterial colonizing Brazilian Maned-wolf, this work investigated samples from eight male captive and free roaming animals originating from different Brazilian geographical regions. Samples for microbiological purposes were collected with swabs and kept in appropriate transport medium. Using routine microbiological techniques, the isolated bacteria were tested toward antimicrobial drugs by the agar disk diffusion method. Results showed that all samples from wild animals were sensitive toward all drugs tested. Conversely, the resistance profile of bacteria isolated from captive animals varied among strains and animal body site location. Escherichia coli samples from prepuce, anus and ear showed multi-resistance toward at least four drugs, especially against erythromycin and tetracycline, followed by Proteus mirabilis and P. vulgaris strains isolated from anus and ear. Among Gram-positive bacteria, strains of coagulase-negative staphylococci showed multi-resistance mainly toward erythromycin and amoxicillin. The work discusses these findings and suggests that profile of multi-resistance bacteria from captive subjects may be attributed to direct contact with human or through lifestyle factors such as feeding, predation or contact of animals with urban animals such as birds, rodents, and insects from surrounding environments. PMID:24688529

  9. Bovine mastitis Staphylococcus aureus: Antibiotic susceptibility profile, resistance genes and molecular typing of methicillin-resistant and methicillin-sensitive strains in China.

    PubMed

    Wang, Dengfeng; Wang, Zhicai; Yan, Zuoting; Wu, Jianyong; Ali, Tariq; Li, Jianjun; Lv, Yanli; Han, Bo

    2015-04-01

    The emergence of methicillin-resistant Staphylococcus aureus (MRSA) infection in dairy animals is of great concern for livestock and public health. The aim of present study was to detect new trends of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) towards antibiotic susceptibility, resistance genes and molecular typing by methods of disc diffusion, multiplex PCR assay and multilocus sequence typing (MLST). A total of 219 S. aureus strains were isolated from bovine mastitis cases from six provinces of China, including 34 MRSA strains. The results revealed that more than 70% isolated strains showed resistance to various antibiotics, and multiple-drugs resistance to more than five categories of antibiotics was found more common. The ermC was the most prevalent resistance gene, followed by other genes; however, ermA was the least frequently detected gene. Twenty-eight mecA-negative MRSA and six mecA-positive MRSA strains were detected, and in which three strains were ST97-MRSA-IV, others were ST965-MRSA-IV, ST6-MRSA-IV and ST9-MRSA-SCCmec-NT. The mecA-negative MRSA strains were found resistant to most of the antibiotics, and harbored aac(6')/aph(2''), aph(3')-III and tetM genes higher than MSSA strains. The resistance to most of the antibiotics was significantly higher in MRSA than in MSSA strains. The MLST profiles showed that these strains mainly belonged to CC5, CC398, CC121 and CC50 lineage, especially within ST97 and ST398, while some novel sequence types (ST2154, ST2165 and ST2166) were identified and deposited in the MLST database. This indicates that the resistance of S. aureus is becoming more complicated by changes in multi-drug resistance mechanism and appearance of mecA-negative MRSA isolates, and importantly, MRSA-IV strains in different MLST types are emerging. PMID:25582604

  10. Chilling resistance of Phaseolus vulgaris and Brassica oleracea under a high-intensity electric field.

    PubMed

    Cakmak, Turgay; Dumlupinar, Rahmi; Erdal, Serkan

    2010-01-01

    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

  11. Electrical Resistivity Survey for Delineation of the Seawater Intrusion in the Çanakkale Plain, NW Turkey

    NASA Astrophysics Data System (ADS)

    Demirci, Alper; Ekinci, Yunus Levent; Kaya, Mehmet Ali

    2013-04-01

    The city of Çanakkale (Dardanelles) is located on the west side of the Biga Peninsula. The Peninsula is delimited by the Strait of Çanakkale, which is the unique water linkage between the Aegean Sea and the Marmara Sea. The study area is covered by quaternary aged sediments. Sar?çay, which originates from the eastern hilly area, accumulates sediment deposits and forms this alluvial basin. Alluvial terrace including sand, gravel and block sized materials is observed towards northeastern part of this basin. There has been six-fold increase in the population and tremendous growth in industrial and environmental activities in Çanakkale city in the last two decades. Thus, there has been necessity of new settlement areas for planned urbanization and the parameters of liquefaction potential and the extent of seawater intrusion should be taken into consideration. To this end, we have carried out Direct Current (DC) electrical resistivity survey on 52 stations to shed light on the thickness of alluvial layers and traces of the seawater intrusion in the Çanakkale plain. We have used maximum half current electrode spacing (AB/2) of 80 m for each station. The acquired apparent resistivity data were processed by using a damped least square inversion algorithm with singular value decomposition (SVD) technique. After obtaining the model parameters (thickness and resistivity) of each resistivity curve, a MATLAB-based visualization algorithm was used for joint representation of the whole resistivity variation of the studied area. The produced psuedo-three dimensional volumetric resistivity distribution images indicated that the western part of investigation area has relatively resistive structures (> 80 ohm.m), which extend to the depth of 3 m. The sudden decrease in resistivity values to downward clearly indicated seawater saturated sediments (0.5-5 ohm.m). On contrary to these low resistivity values observed at the western part of the city, the central and eastern parts are characterized by relatively higher resistivity values ranging between 30-70 ohm.m. These results clearly outlined the extension of saturated zones. Due to the active tectonism of the region, and highly saturated zones, preventive measures should be considered against liquefaction risks in construction of engineering structures by local authorities. Keywords: Resistivity, Seawater, Saturation, Çanakkale, Turkey

  12. Investigation of degree of saturation in landfill liners using electrical resistivity imaging.

    PubMed

    Kibria, Golam; Hossain, Md Sahadat

    2015-05-01

    During construction of compacted clay liners and evapotranspiration (ET) covers, quality control involves laboratory and field tests in individual lifts. However, the available methods may be inadequate to determine non-uniform compaction conditions, poor bonding of lifts, and/or variable soil composition. Moreover, the applicability of the available methods is restricted, in many instances, when spatial variability of the subsurface is expected. Resistivity Imaging (RI) is a geophysical method employed to investigate a large area in a rapid and non-destructive way. High resistivity of clay liner soil is an indication of a low degree of saturation, high air-filled voids, and poor lift bonding. To utilize RI as a quality control tool in a landfill liner, it is important to determine the saturation condition of the compacted soils because compaction and permeability of liner soil are functions of degrees of saturation. The objective of the present study is to evaluate the degree of saturation of a municipal solid waste (MSW) landfill liner, using RI. Electrical resistivity tests were performed in the laboratory, at varied moisture contents and dry unit weights, on four types of soil samples, i.e., highly plastic clay (CH), low plastic clay (CL), Ca-bentonite, and kaolinite. According to the experimental results, electrical resistivity of the specimens decreased as much as 15.3 times of initial value with increase in the degrees of saturation from 23% to 100%. In addition, cation exchange capacity (CEC) substantially affected resistivity. A multiple linear regression (MLR) model was developed to correlate electrical resistivity with degree of saturation and CEC using experimental results. Additionally, RI tests were conducted on compacted clay liners to determine the degrees of saturation, and predicted degrees of saturation were compared with the in-situ density tests. The study results indicated that the developed model can be utilized for liner soils having CEC, resistivity and degrees of saturation between 13.3 and 79cmol+/kg, and 2.6 and 504.3Ohmm, and 21.8% to 100%; respectively. PMID:25758909

  13. Comparison of selected gene expression profiles in sensitive and resistant cancer cells treated with doxorubicin and Selol

    PubMed Central

    Grabowska, Agnieszka; Ksi??ek, Iza; Sitarz, Karolina; Suchocki, Piotr; Anuszewska, El?bieta

    2014-01-01

    Aim of the study Cellular resistance is strongly correlated with the risk of failure in doxorubicin (DOX) treatment, and the knowledge of the mechanisms of resistance and its possible modulation is still very limited. Material and methods In this study, we assessed the effect of 5% Selol and DOX on the expression of genes that affect cell proliferation in the resistant KB-V1 and sensitive HeLa cell lines, using RT2 ProfilerTM PCR Array matrix “Human Cancer Drug Resistance and Metabolism” (SABiosciences). Results We showed that HeLa and KB-V1 cell lines, characterised by varying susceptibility to DOX, have different genetic profiles as regards the studied genes. KB-V1 cells show overexpression of MYC and BCL2 genes, which encode proteins with anti apoptotic properties. Selol, when used in KB-V1 cells, reduced the expression of MYC and BCL2 genes, suggested as a new therapeutic target in the treatment of cancers resistant to cytostatic drugs. Conclusions The results suggest that Selol could be used as a modulator that enhances the cytotoxic effects of doxorubicin, particularly in cells resistant to this drug. PMID:24966790

  14. Correlation between Electrical Resistivity, Particle Dissolution, Precipitation of Dispersoids, and Recrystallization Behavior of AA7020 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Eivani, A. R.; Ahmed, H.; Zhou, J.; Duszczyk, J.

    2009-10-01

    This research concerns the effect of homogenization treatment on the electrical resistivity of AA7020 aluminum alloy variants with different Zr and Cr contents. Small changes in the Zr and Cr contents of the as-cast alloy increase the electrical resistivity significantly. After employing various homogenization treatments, the electrical resistivity decreases, which is due to the depletion of Zr, Cr, and Mn in the matrix, by forming small dispersoids. The optimum treatment proposed in order to obtain the smallest recrystallized grains is to hold the material at 550 °C for 24 hours, which results in the lowest electrical resistivity. The viability of the proposed treatment was tested through hot compression tests and static annealing. Indeed, the samples homogenized at 550 °C for 24 hours showed the smallest recrystallized grains compared to those homogenized at other temperatures.

  15. The pleiotropic profile of the indirubin derivative 6BIO overcomes TRAIL resistance in cancer.

    PubMed

    Braig, Simone; Bischoff, Fabian; Abhari, Behnaz A; Meijer, Laurent; Fulda, Simone; Skaltsounis, Leandros; Vollmar, Angelika M

    2014-09-15

    TRAIL (TNF?-related apoptosis-inducing factor) has been promoted as a promising anti-cancer agent. Unfortunately many tumor cells develop resistance towards TRAIL due to numerous defects in apoptotic signaling. To handle this problem combination therapy with compounds affecting as many different anti-apoptotic targets as possible might be a feasible approach. The bromo-substituted indirubin derivative 6BIO meets this challenge: Treatment of breast cancer and bladder carcinoma cell lines with micromolar concentrations of 6BIO abrogates cellular growth and induces apoptosis. Combination of subtoxic amounts of 6BIO with ineffective doses of TRAIL completely abolishes proliferation and long-term survival of cancer cells. As shown in two-dimensional as well as three-dimensional cell culture models, 6BIO potently augments TRAIL-induced apoptosis in cancer cell lines. The potent chemosensitizing effect of 6BIO to TRAIL-mediated cell death is due to the pleiotropic inhibitory profile of 6BIO. As shown previously, 6BIO abrogates STAT3, PDK1 as well as GSK3 signaling and moreover, inhibits the expression of the anti-apoptotic Bcl-2 family members Bcl-xL and Mcl-1 on mRNA as well as on protein level, as demonstrated in this study. Moreover, the expression of cFLIP and cIAP1 is significantly downregulated in 6BIO treated cancer cell lines. In sum (subtoxic concentration of) the multi-kinase inhibitor 6BIO serves as a potent chemosensitizing agent fighting TRAIL resistant cancer cells. PMID:25069048

  16. Mining Genes Involved in Insecticide Resistance of Liposcelis bostrychophila Badonnel by Transcriptome and Expression Profile Analysis

    PubMed Central

    Dou, Wei; Shen, Guang-Mao; Niu, Jin-Zhi; Ding, Tian-Bo; Wei, Dan-Dan; Wang, Jin-Jun

    2013-01-01

    Background Recent studies indicate that infestations of psocids pose a new risk for global food security. Among the psocids species, Liposcelis bostrychophila Badonnel has gained recognition in importance because of its parthenogenic reproduction, rapid adaptation, and increased worldwide distribution. To date, the molecular data available for L. bostrychophila is largely limited to genes identified through homology. Also, no transcriptome data relevant to psocids infection is available. Methodology and Principal Findings In this study, we generated de novo assembly of L. bostrychophila transcriptome performed through the short read sequencing technology (Illumina). In a single run, we obtained more than 51 million sequencing reads that were assembled into 60,012 unigenes (mean size?=?711 bp) by Trinity. The transcriptome sequences from different developmental stages of L. bostrychophila including egg, nymph and adult were annotated with non-redundant (Nr) protein database, gene ontology (GO), cluster of orthologous groups of proteins (COG), and KEGG orthology (KO). The analysis revealed three major enzyme families involved in insecticide metabolism as differentially expressed in the L. bostrychophila transcriptome. A total of 49 P450-, 31 GST- and 21 CES-specific genes representing the three enzyme families were identified. Besides, 16 transcripts were identified to contain target site sequences of resistance genes. Furthermore, we profiled gene expression patterns upon insecticide (malathion and deltamethrin) exposure using the tag-based digital gene expression (DGE) method. Conclusion The L. bostrychophila transcriptome and DGE data provide gene expression data that would further our understanding of molecular mechanisms in psocids. In particular, the findings of this investigation will facilitate identification of genes involved in insecticide resistance and designing of new compounds for control of psocids. PMID:24278202

  17. Three dimensional modeling and inversion of Borehole-surface Electrical Resistivity Data

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Liu, D.; Liu, Y.; Qin, M.

    2013-12-01

    After a long time of exploration, many oil fields have stepped into the high water-cut period. It is sorely needed to determining the oil-water distribution and water flooding front. Borehole-surface electrical resistivity tomography (BSERT) system is a low-cost measurement with wide measuring scope and small influence on the reservoir. So it is gaining more and more application in detecting water flooding areas and evaluating residual oil distribution in oil fields. In BSERT system, current is connected with the steel casing of the observation well. The current flows along the long casing and transmits to the surface through inhomogeneous layers. Then received electric potential difference data on the surface can be used to inverse the deep subsurface resistivity distribution. This study presents the 3D modeling and inversion method of electrical resistivity data. In an extensive literature, the steel casing is treated as a transmission line current source with infinite small radius and constant current density. However, in practical multi-layered formations with different resistivity, the current density along the casing is not constant. In this study, the steel casing is modeled by a 2.5e-7 ohm-m physical volume that the casing occupies in the finite element mesh. Radius of the casing can be set to a little bigger than the true radius, and this helps reduce the element number and computation time. The current supply point is set on the center of the top surface of the physical volume. The homogeneous formation modeling result shows the same precision as the transmission line current source model. The multi-layered formation modeling result shows that the current density along the casing is high in the low-resistivity layer, and low in the high-resistivity layer. These results are more reasonable. Moreover, the deviated and horizontal well can be simulated as simple as the vertical well using this modeling method. Based on this forward modeling method, the inversion procedure can be implemented by using open source software R3t (Lancaster University, UK). First, establish triangular prism meshes for the BSERT model by using the freeware gmsh (Geuzaine and Remacle, 2009). Second, transform the mesh data file into R3t required format and set the inversion areas in the mesh. Third, attach resistivity to the elements in the mesh according to the local geology analysis and resistivity logging results. Fourth, assign the field measured electric potential data to electrodes. Finally, set the inversion parameters and solve the inversion problem. Inversion results of synthetic modeling data can match well with the positions of anomalies and validate that the method works on the inversion of the borehole-surface electric resistivity data. Then filed example of Changqing oil field in China is carried out using the inversing method.

  18. Improving the Erosion Resistance of Electrical Insulating Materials Using Nano Fillers

    NASA Astrophysics Data System (ADS)

    El-Hag, A.; Ul-Haq, S.; Jayaram, S.; Cherney, E.

    2007-08-01

    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.

  19. Mapping of quick clay by electrical resistivity tomography under structural constraint

    NASA Astrophysics Data System (ADS)

    Bazin, S.; Pfaffhuber, A. A.

    2013-11-01

    Geotechnical projects usually rely on traditional sounding and drilling investigations. Drilling only provides point information and the geology needs to be interpolated between these points. Near surface geophysical methods can provide information to fill those gaps. Norwegian case studies are presented to illustrate how two-dimensional electrical resistivity tomography (ERT) can be used to accurately map the extent of quick clay deposits. Quick clay may be described as highly sensitive marine clay that changes from a relatively stiff condition to a liquid mass when disturbed. Quick clay slides present a geo-hazard and therefore layers of sensitive clay need to be mapped in detail. They are usually characterized by higher resistivity than non-sensitive clay and ERT is therefore a suitable approach to identify their occurrence. However, our experience shows that ERT cannot resolve this small resistivity contrast near large anomalies such as a bedrock interface. For this reason, a constrained inversion of ERT data was applied to delineate quick clay extent both vertically and laterally. As compared to the conventional unconstrained inversions, the constrained inversion models exhibit sharper resistivity contrasts and their resistivity values agree better with in situ measurements.

  20. Electrical measurement of a high-frequency, high-capacitance piezoceramic resonator with resistive electrodes.

    PubMed

    Mezheritsky, Alex V

    2005-08-01

    In a thin and large area PZT-ceramics piezoresonator (PR) with relatively low resonance impedance, caused by high-frequency resonance and high PR capacitance, the effect of electrode resistivity and parasitic resistive and inductive elements in the measurement fixture results in significant distortion of the measured thickness-mode (longitudinal TL, shear TS) resonance response-resonance frequency shifts and characteristics deformation. This distortion may not allow the precise measurement of the PR characteristic frequencies, quality factor, and electromechanical coupling coefficient so essential to a complete PR and material characterization. A theoretical description of the "energy-trap" phenomena in a thickness-vibrating PR with resistive electrodes is presented. To interpret electrical measurements, the electromechanical model, including for completeness both the PR with resistive electrodes (as a system with distributed parameters) and the measurement fixture, is developed. The method of two contact points on the electrode provides deep sharpening and exact determination of the PR resonance. For the optimal disposition of the contact fingers, the resonance bandwidth of a real PR with resistive electrodes is even more pointed than that for the ideal PR. PMID:16245592

  1. Size effects of lead-free solder joint thickness under shear creep based on micro-electrical-resistance strain

    NASA Astrophysics Data System (ADS)

    Jiang, Li; Zhang, Guiying; Zhou, Jieming

    2008-08-01

    Single shear lap creep specimens with a 1 mm2 cross sectional area between thin copper strips were developed and fabricated using a lead-free solder (Sn-3.5Ag) to quantify their electrical resistance. The electrical-resistance strain of solder joints with different thicknesses (0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.50 mm) were measured by a tailor-made in situ micro-electrical-resistance measurement. The results showed that the solder joints with 0.25 mm thickness yielded a minimum electrical-resistance strain and the longest creep life. Thicker solder joints produced a larger electrical-resistance strain and a shorter lifetime if the thickness >0.25 mm. In contrast, thinner solder joints produced a larger electrical-resistance strain and a shorter lifetime if the thickness <0.25 mm. A quantificational relationship between the electrical-resistance strain and the solder joint thickness was obtained according to the experimental data. On the other hand, solder joints with different thicknesses (corresponding to those used in the experiment) were studied by the finite element method (FEM). The results showed that the creep strain of solder joints was the lowest with 0.25 mm thickness, and the creep strain increased with the increment in the thickness if the thickness >0.25 mm but decreased with the increment in the thickness if the thickness <0.25 mm. The quantificational relationship between the creep strain and solder joints thickness was obtained according to the data of FEM. Finally, the quantificational relationship between the creep strain and the electrical-resistance strain was obtained by combining the experimental data and the FEM data.

  2. Electrical Resistance of Nb3Sn\\/Cu Splices Produced by Electromagnetic Pulse Technology and Soft Soldering

    Microsoft Academic Search

    D Schoerling; S Heck; C Scheuerlein; S Atieh; R Schaefer

    2011-01-01

    The electrical interconnection of Nb3Sn\\/Cu strands is a key issue for the construction of Nb3Sn based damping ring wigglers and insertion devices for third generation light sources. We compare the electrical resistance of Nb3Sn\\/Cu splices manufactured by solid state welding using Electromagnetic Pulse Technology (EMPT) with that of splices produced by soft soldering with two different solders. The resistance of

  3. Virulence and resistance gene profiles of staphylococcus aureus strains isolated from ready-to-eat foods.

    PubMed

    Baumgartner, Andreas; Niederhauser, Isabel; Johler, Sophia

    2014-07-01

    Staphylococcal food poisoning represents the most prevalent foodborne intoxication worldwide. Oral intake of staphylococcal enterotoxins from food can result in emesis and diarrhea and can be fatal in children and the elderly. Few data have been available on the characteristics and sources of Staphylococcus aureus strains isolated from ready-to-eat (RTE) foods. In this study, we used a DNA microarray to determine virulence and antimicrobial resistance gene profiles of S. aureus from RTE foods. A total of 267 S. aureus strains isolated from 244 RTE foods were investigated. The isolates originated from precooked foods (41% of isolates), meat and fish products (17%), cheese (13%), delicatessen salads (8%), sandwiches and canapés (8%), confectionery and bakery products (6%), and various other RTE foods (7%). Eleven samples (5%), of which 9 were raw milk cheeses, contained > 10(5) CFU/g, which is considered a health risk. Four S. aureus strains were associated with intoxications; three cases were linked to consumption of cheese and one case was linked to consumption of potato salad. DNA microarray results revealed that one-third of the tested strains had at least one major enterotoxin gene (sea through see). We also detected the toxic shock syndrome gene (18% of isolates) and various genes conferring antimicrobial resistance, including genes involved in resistance to beta-lactams (blaZ, 72% of isolates), methicillin (mecA, 1% of isolates), and vancomycin (vanB, 1% of isolates). S. aureus strains were most frequently assigned to clonal complex (CC) 30 (17% of isolates), CC8 (12%), CC15 (11%), and CC45 (10%), which are commonly detected in humans colonized or infected with S. aureus. Although a large proportion of the tested food items contained milk, we did not detect CC705, the most prevalent clonal complex among S. aureus isolates from bovine mastitis milk. Our results suggest that S. aureus isolates from RTE foods do not commonly originate from animals but more likely come from food handlers who contaminate foods. PMID:24988036

  4. Electrical Resistivity Measurements in Sandstone During CH4 Hydrate Formation and CH4-CO2 Exchange

    NASA Astrophysics Data System (ADS)

    Birkedal, K.; Hauge, L.; Ersland, G.; Graue, A.

    2012-12-01

    The electrical properties of hydrate bearing sediments change with mineralogy, porosity, hydrate saturation, brine salinity, and mobility of the formation brine. Reliable calibration data is therefore essential for correct interpretation. Electrical resistivity measurements have been conducted on homogeneous Bentheim sand during CH4 hydrate formation. Various initial conditions (salinity and Sw) were used to determine the robustness of resistivity as a measure of hydrate saturation. Two setups with different electrode-arrangements were used; the first setup was a four electrode core holder without imaging capabilities, the second a two-electrode core holder used in combination with MRI to calibrate saturation data. The agreement between the two setups was good and there was little variation in phase angle. An initial resistivity decrease was observed at the initiation of hydrate growth for all experiments. This effect was more pronounced with lower initial salinities. Further increase in hydrate saturation resulted in reduced pore connectivity and increased tortuosity which resulted in increased resistivity (45-2487 k?). Only CH4 and water were used to form hydrate. The brine NaCl concentration of the remaining brine solution therefore increased during hydrate growth. Dynamic Rw and R0 values were incorporated into Archie's equations to account for changes in brine composition during hydrate formation. Resistivity was also measured during exchange between CH4-hydrate and CO2. There was an immediate resistivity and pressure response as CO2 was introduced to the system. This may be explained by higher water activity and CO2-hydrate growth at the trans-axial core face as CO2 is the preferred guest molecule at the experimental conditions. A spontaneous exchange therefore occurs, where the change in enthalpy accelerates the exchange. The resistivity showed a continuous decreasing trend after CO2 was introduced. This is explained by local in-equilibrium where dissociation and reformation occurs as simultaneous events, causing rearrangement of hydrate crystals and water. Trapped water re-organizing with a continuous conductive brine layer will result in a resistivity decrease. The performance of the CO2 injection was sensitive to heterogeneities in initial saturation distribution.

  5. Electrical current profile of a confined isotropic liquid sample: Biological systems and liquid crystals applications

    NASA Astrophysics Data System (ADS)

    Ribeiro de Almeida, R. R.; Michels, F. S.; Steffen, V.; Lenzi, E. K.; Zola, R. S.; Evangelista, L. R.

    2013-11-01

    The electrical current profile in a liquid sample containing ionic impurities, submitted to a time-dependent external voltage, is determined in the framework of the Poisson-Nernst-Planck (PNP) diffusional model. The boundary conditions at the limiting electrodes include the situations of blocking electrodes, generalized Chang-Jaffé (specific adsorption), and the adsorption-desorption of positive and negative ions at the interface, governed by a kinetic equation in the Langmuir's approximation. The current-voltage characteristics of the confined system are obtained in the presence of an arbitrary time-dependent applied potential of small amplitude (linear approximation). The calculations are potentially useful for modeling and interpreting experimental situations found in biological cells and liquid crystals samples.

  6. Effect of functional electrical stimulation (FES) combined with robotically assisted treadmill training on the EMG profile.

    PubMed

    Askari, S; Chao, T; Conn, L; Partida, E; Lazzaretto, T; See, P A; Chow, C; de Leon, R D; Won, D S

    2011-01-01

    Functional electrical stimulation (FES) is used to assist spinal cord injury patients during walking. However, FES has yet to be shown to have lasting effects on the underlying neurophysiology which lead to long-term rehabilitation. A new approach to FES has been developed by which stimulation is timed to robotically controlled movements in an attempt to promote long-term rehabilitation of walking. This approach was tested in a rodent model of spinal cord injury. Rats who received this FES therapy during a 2-week training period exhibited peak EMG activity during the appropriate phase of the gait cycle; whereas, rats who received stimulation which was randomly timed with respect to their motor activity exhibited no clear pattern in their EMG profile. These results from our newly developed FES system serve as a launching point for many future studies to test and understand the long-term effect of FES on spinal cord rehabilitation. PMID:22254981

  7. Novel laboratory methods for determining the fine scale electrical resistivity structure of core

    NASA Astrophysics Data System (ADS)

    Haslam, E. P.; Gunn, D. A.; Jackson, P. D.; Lovell, M. A.; Aydin, A.; Prance, R. J.; Watson, P.

    2014-12-01

    High-resolution electrical resistivity measurements are made on saturated rocks using novel laboratory instrumentation and multiple electrical voltage measurements involving in principle a four-point electrode measurement but with a single, moving electrode. Flat, rectangular core samples are scanned by varying the electrode position over a range of hundreds of millimetres with an accuracy of a tenth of a millimetre. Two approaches are tested involving a contact electrode and a non-contact electrode arrangement. The first galvanic method uses balanced cycle switching of a floating direct current (DC) source to minimise charge polarisation effects masking the resistivity distribution related to fine scale structure. These contacting electrode measurements are made with high common mode noise rejection via differential amplification with respect to a reference point within the current flow path. A computer based multifunction data acquisition system logs the current through the sample and voltages along equipotentials from which the resistivity measurements are derived. Multiple measurements are combined to create images of the surface resistivity structure, with variable spatial resolution controlled by the electrode spacing. Fine scale sedimentary features and open fractures in saturated rocks are interpreted from the measurements with reference to established relationships between electrical resistivity and porosity. Our results successfully characterise grainfall lamination and sandflow cross-stratification in a brine saturated, dune bedded core sample representative of a southern North Sea reservoir sandstone, studied using the system in constant current, variable voltage mode. In contrast, in a low porosity marble, identification of open fracture porosity against a background very low matrix porosity is achieved using the constant voltage, variable current mode. This new system is limited by the diameter of the electrode that for practical reasons can only be reduced to between 0.5 and 0.75 mm. Improvements to this resolution may be achieved by further reducing the electrode footprint to 0.1 mm × 0.1 mm using a novel high-impedance, non-contact potential probe. Initial results with this non-contact electric potential sensor indicate the possibility for generating images with grain-scale resolution.

  8. 3-D Time-lapse Electrical Resistivity Monitoring of Injected CO2 in a Shallow Aquifer

    NASA Astrophysics Data System (ADS)

    Doetsch, J.; Vest Christiansen, A.; Auken, E.; Fiandaca, G.; Graham Cahill, A.

    2013-12-01

    Contamination of potable groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment, we investigate if surface electrical resistivity tomography (ERT) can detect dissolved CO2 in a shallow aquifer. For this purpose, we injected CO2 at a depth of 5 and 10 m and monitored its migration using 320 electrodes on a 126 m × 20 m surface grid. A fully automated acquisition system continuously collected data and uploaded it into an online database. The large amount of data allows for time-series analysis using geostatistical techniques for noise estimation and data interpolation to compensate for intermittent instrument failure. We estimate a time-dependent noise level for each ERT configuration, taking data variation and measurement frequency into account. A baseline inversion reveals the geology at the site consisting of aeolian sands near the surface and glacial sands below 5 m depth. Directly following the injection, we image the CO2 gas phase in the aquifer as an increase in resistivity and the higher water saturation in the unsaturated zone as a decrease in resistivity. At later times, the 2-D and 3-D time-lapse inversions clearly image the dissolved CO2 plume with decreased electrical resistivity values. We can image the geochemical changes induced by the dissolved CO2 until the end of the acquisition, 120 days after the injection start. During these 120 days, the CO2 migrates about 40 m in the expected groundwater flow direction (towards south-west). Water electrical conductivity (EC) sampling using 68 sensors in 31 wells allows for very good verification of the ERT results. Water EC and ERT results generally agree very well, with the water sampling showing some fine scale variations that cannot be resolved by the ERT. The ERT images have their strength in outlining the plume's shape in three dimensions and in being able to image the plume outside the well field. These results highlight the potential for imaging dissolved CO2 using non-intrusive surface electrical resistivity tomography.

  9. Continuous resistivity profiling data from the upper Neuse River Estuary, North Carolina, 2004-2005

    USGS Publications Warehouse

    Cross, VeeAnn A.; Bratton, John F.; Bergeron, Emile; Meunier, Jeff K.; Crusius, John; Koopmans, Dirk

    2006-01-01

    The Neuse River Estuary in North Carolina has suffered impacts of eutrophication in recent years. As part of a larger project to better constrain nutrient budgets in the estuary, field investigations were performed to study occurrence and discharge of fresh and brackish ground water and nutrients beneath the estuary itself (fig. 1). A Continuous Resistivity Profiling (CRP) system (Manheim and others, 2004) was used to map the depth of the freshwater-saltwater interface (FSI) in sub-estuarine groundwater. This study area serves as a typological representation of a submarine groundwater environment characteristic of a shallow estuary in a wide coastal plain that has not experienced glaciation. Similar settings extend from New Jersey to Georgia, and along the Gulf of Mexico in the U.S. This report archives 29 lines of data collected during 2004 and 2005 surveys representing almost 210 km of survey lines. These data are further explained in the Data Processing section of the report and previews available of the processed data are available.

  10. Metabolite profiles of rice cultivars containing bacterial blight-resistant genes are distinctive from susceptible rice.

    PubMed

    Wu, Jiao; Yu, Haichuan; Dai, Haofu; Mei, Wenli; Huang, Xin; Zhu, Shuifang; Peng, Ming

    2012-08-01

    The metabolic changes of bacterial blight-resistant line C418/Xa23 generated by molecular marker-assisted selection (n= 12), transgenic variety C418-Xa21 generated by using the Agrobacterium-mediated system (n= 12), and progenitor cultivar C418 (n= 12) were monitored using gas chromatography/mass spectrometry. The validation, discrimination, and establishment of correlative relationships between metabolite signals were performed by cluster analysis, principal component analysis, and partial least squares-discriminant analysis. Significant and unintended changes were observed in 154 components in C418/Xa23 and 48 components in C418-Xa21 compared with C418 (P< 0.05, Fold change > 2.0). The most significant decreases detected (P< 0.001) in both C418/Xa23 and C418-Xa21 were in three amino acids: glycine, tyrosine, and alanine, and four identified metabolites: malic acid, ferulic acid, succinic acid, and glycerol. Linoleic acid was increased specifically in C418/Xa23 which was derived from traditional breeding. This line, possessing a distinctive metabolite profile as a positive control, shows more differences vs. the parental than the transgenic line. Only succinic acid that falls outside the boundaries of natural variability between the two non-transgenic varieties C418 and C418/Xa23 should be further investigated with respect to safety or nutritional impact. PMID:22687573

  11. Quantification and Size-profiling of Extracellular Vesicles Using Tunable Resistive Pulse Sensing

    PubMed Central

    Maas, Sybren L. N.; De Vrij, Jeroen; Broekman, Marike L. D.

    2014-01-01

    Extracellular vesicles (EVs), including ‘microvesicles’ and ‘exosomes’, are highly abundant in bodily fluids. Recent years have witnessed a tremendous increase in interest in EVs. EVs have been shown to play important roles in various physiological and pathological processes, including coagulation, immune responses, and cancer. In addition, EVs have potential as therapeutic agents, for instance as drug delivery vehicles or as regenerative medicine. Because of their small size (50 to 1,000 nm) accurate quantification and size profiling of EVs is technically challenging. This protocol describes how tunable resistive pulse sensing (tRPS) technology, using the qNano system, can be used to determine the concentration and size of EVs. The method, which relies on the detection of EVs upon their transfer through a nano sized pore, is relatively fast, suffices the use of small sample volumes and does not require the purification and concentration of EVs. Next to the regular operation protocol an alternative approach is described using samples spiked with polystyrene beads of known size and concentration. This real-time calibration technique can be used to overcome technical hurdles encountered when measuring EVs directly in biological fluids. PMID:25350417

  12. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail, III, William Banning (Bothell, WA); Momii, Steven Thomas (Seattle, WA)

    2001-01-01

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  13. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail III, William Banning; Momii, Steven Thomas

    2003-06-10

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  14. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail, III, William Banning (Bothell, WA); Momii, Steven Thomas (Seattle, WA)

    2000-01-01

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  15. Lipid Profile In Relation To Anthropometric Indices and Insulin Resistance in Overweight Women with Polycystic Ovary Syndrome

    PubMed Central

    Saghafi-Asl, Maryam; Pirouzpanah, Saeed; Ebrahimi-Mameghani, Mehranghiz; Asghari-Jafarabadi, Mohammad; Aliashrafi, Soudabeh; Sadein, Bita

    2013-01-01

    Background: The present study was aimed to investigate lipid profile in relation to anthropometric indices and insulin resistance in overweight or obese women with polycystic ovary syndrome (PCOS). Methods: In this cross-sectional study, lipid profile and anthropometric indices including body mass index (BMI), waist and hip circumference, waist to hip ratio (WHR), and waist to height ratio (WHtR) were evaluated in 63 overweight or obese PCOS patients subdivided into insulin-resistant (IR) and non insulin-resistant (NIR) groups. IR was defined as homeostasis model of insulin resistance (HOMA-IR) ?3.8. Results: Fasting insulin concentration and HOMA-IR were higher (P<0.001) and high-density lipoprotein cholesterol (P=0.012) was lower in IR group. All of the anthropometric measures other than WHR and BMI showed significant correlations with several lipid parameters. Amongst, WHtR showed the strongest correlation with total cholesterol (TC) (r=0.37; P=0.004) and low density lipoprotein cholesterol (LDL-C) (r=0.33; P=0.011) in the whole PCOS patients. Conclusion: Anthropometric characteristics (especially BMI and hip circum­ference) are more important parameters correlated to lipid profile than IR in overweight or obesePCOS patients, confirming the importance of early treat­ment of obesity to prevent dyslipidemia in the future. PMID:24688970

  16. Time-lapse electrical resistivity investigations for imaging the grouting injection in shallow subsurface cavities.

    PubMed

    Farooq, Muhammad; Park, Samgyu; Kim, Jung Ho; Song, Young Soo; Amjad Sabir, Mohammad; Umar, Muhammad; Tariq, Mohammad; Muhammad, Said

    2014-01-01

    The highway of Yongweol-ri, Muan-gun, south-western part of the South Korean Peninsula, is underlain by the abandoned of subsurface cavities, which were discovered in 2005. These cavities lie at shallow depths with the range of 5?15 meters below the ground surface. Numerous subsidence events have repeatedly occurred in the past few years, damaging infrastructure and highway. As a result of continuing subsidence issues, the Korean Institute of Geosciences and Mineral Resources (KIGAM) was requested by local administration to resolve the issue. The KIGAM used geophysical methods to delineate subsurface cavities and improve more refined understanding of the cavities network in the study area. Cement based grouting has been widely employed in the construction industry to reinforce subsurface ground. In this research work, time-lapse electrical resistivity surveys were accomplished to monitor the grouting injection in the subsurface cavities beneath the highway, which have provided a quasi-real-time monitoring for modifying the subsurface cavities related to ground reinforcement, which would be difficult with direct methods. The results obtained from time-lapse electrical resistivity technique have satisfactory imaged the grouting injection experiment in the subsurface cavities beneath the highway. Furthermore, the borehole camera confirmed the presence of grouting material in the subsurface cavities, and hence this procedure increases the mechanical resistance of subsurface cavities below the highway. PMID:24578621

  17. Time-Lapse Electrical Resistivity Investigations for Imaging the Grouting Injection in Shallow Subsurface Cavities

    PubMed Central

    Farooq, Muhammad; Kim, Jung Ho; Song, Young Soo; Amjad Sabir, Mohammad; Umar, Muhammad; Tariq, Mohammad; Muhammad, Said

    2014-01-01

    The highway of Yongweol-ri, Muan-gun, south-western part of the South Korean Peninsula, is underlain by the abandoned of subsurface cavities, which were discovered in 2005. These cavities lie at shallow depths with the range of 5?15 meters below the ground surface. Numerous subsidence events have repeatedly occurred in the past few years, damaging infrastructure and highway. As a result of continuing subsidence issues, the Korean Institute of Geosciences and Mineral Resources (KIGAM) was requested by local administration to resolve the issue. The KIGAM used geophysical methods to delineate subsurface cavities and improve more refined understanding of the cavities network in the study area. Cement based grouting has been widely employed in the construction industry to reinforce subsurface ground. In this research work, time-lapse electrical resistivity surveys were accomplished to monitor the grouting injection in the subsurface cavities beneath the highway, which have provided a quasi-real-time monitoring for modifying the subsurface cavities related to ground reinforcement, which would be difficult with direct methods. The results obtained from time-lapse electrical resistivity technique have satisfactory imaged the grouting injection experiment in the subsurface cavities beneath the highway. Furthermore, the borehole camera confirmed the presence of grouting material in the subsurface cavities, and hence this procedure increases the mechanical resistance of subsurface cavities below the highway. PMID:24578621

  18. Simultaneous measurements of thermopower, thermal conductivity, and electrical resistivity between 1.2 and 350 K

    NASA Astrophysics Data System (ADS)

    Chaussy, J.; Guessous, A.; Mazuer, J.

    1981-11-01

    We described a fast-cooling cryostat with a novel cooling system using a nitrogen heat pipe. The principal feature of the cryogenic assembly is an evacuated calorimeter containing a heat sink which can be maintained successively at 1, 4.2, and 77 K during the experiment. This allows sample regulation from 1.5 to 350 K. An electronic circuit including noise filters and nanovoltmeters is used to measure the electrical resistivity, thermal conductivity, and thermoelectric power of conducting or semiconducting materials. We used a commercially available Au-Fe-chromel couple as the working thermocouple. First, we calibrated it against germanium and platinum resistance thermometers, and compared the thermoelectric scale so obtained with previous calibrations. We report a preliminary test on pure lead which enabled us to obtain the absolute thermoelectric powers of AuFe and chromel and also to estimate the parasitic radiative heat transfer during thermal conductivity measurements. We also report the three transport properties of the title for an amorphous Ce0.3Al0.7 alloy prepared by sputtering a crystalline CeAl3 compound. The thermal conductivity and electrical resistivity were essentially those associated with amorphous materials. The thermoelectric power exhibited structure at low temperatures which suggests that a weak magnetism appeared in this glassy structure formed from the typical Kondo compound CeAl3.

  19. Environmental monitoring of leaks using time-lapsed long electrode electrical resistivity

    NASA Astrophysics Data System (ADS)

    Rucker, Dale F.; Fink, James B.; Loke, Meng H.

    2011-08-01

    Highly industrialized areas pose challenges for surface electrical resistivity characterization due to metallic infrastructure. The infrastructure is typically more conductive than the desired targets and will mask the deeper subsurface information. The risk of this occurring may be minimized if steel-cased wells are used as long electrodes in the area near the target. We demonstrate a method of using long electrodes to electrically monitor a simulated leak from an underground storage tank with both synthetic examples and a field demonstration. Although the method of using long electrodes has been proposed by others, no time-lapse resistivity data have been collected, modeled, and analyzed within a nuclear waste tank farm environment. Therefore, the main objective of this work was to test whether the long electrode method using steel-cased wells can be employed to spatially and temporally track simulated leaks in a highly industrialized setting. A secondary objective was to apply a time-lapse regularization procedure in the inverse modeling code, similar to the 4D tomography approach by Kim et al. (2009), and to test the procedure's effect on the quality of the outcome regarding plume intensity and position. For the synthetic examples, a simple target of varying electrical properties was placed beneath different types of layers of low resistivity to simulate the effects of the infrastructure. Both surface and long electrodes were tested on the synthetic domain, and the test cases covered a variety of survey parameters including low and high electrode density, noise, array type, and the explicit location of the wells relative to the target. All data were processed in four dimensions, where the regularization procedure was applied in both the time and space domains. The synthetic test case showed that the long electrode resistivity method could detect relative changes in resistivity that was commensurate with the differing target properties. The surface electrodes, on the other hand, had a more difficult time matching the original target's footprint unless the electrodes were distributed at a greater density on the surface. The simulated tank leak in the field experiment was conducted by injecting a high conductivity fluid in a perforated well within the S tank farm at the Hanford Site, and the resistivity measurements were made before and after the leak test. The field results showed a lowered resistivity feature develops south of the injection site after cessation of the injections. The parameter used in the time-lapsed inversion had a strong influence on the differences in inverted resistivity between the pre- and post-injection datasets, but the interpretation of the target was consistent across all values of the parameter. The long electrode electrical resistivity monitoring (ERM) method may provide a tool for near real-time monitoring of leaking underground storage tanks given a sufficient density of wells.

  20. Effect of high-temperature corrosion on the gas-abrasive resistance of electric-arc coatings

    Microsoft Academic Search

    M. M. Student; H. V. Pokhmurs’ka; V. V. Hvozdets’kyi; M. Ya. Holovchuk; M. S. Romaniv

    2009-01-01

    We study the high-temperature gas-abrasive wear resistance of electric-arc coatings sprayed from powder wires. It is shown\\u000a that the wear resistance of these coatings increases with temperature. This is explained by the effect of strengthening of\\u000a lamellae in the coating, segregation of the dispersed phases, and the appearance of aluminum and chromium oxides (characterized\\u000a by high shock resistance) both on

  1. Four-point probe electrical resistivity scanning system for large area conductivity and activation energy mapping.

    PubMed

    Shimanovich, Klimentiy; Bouhadana, Yaniv; Keller, David A; Rühle, Sven; Anderson, Assaf Y; Zaban, Arie

    2014-05-01

    The electrical properties of metal oxides play a crucial role in the development of new photovoltaic (PV) systems. Here we demonstrate a general approach for the determination and analysis of these properties in thin films of new metal oxide based PV materials. A high throughput electrical scanning system, which facilitates temperature dependent measurements at different atmospheres for highly resistive samples, was designed and constructed. The instrument is capable of determining conductivity and activation energy values for relatively large sample areas, of about 72 × 72 mm(2), with the implementation of geometrical correction factors. The efficiency of our scanning system was tested using two different samples of CuO and commercially available Fluorine doped tin oxide coated glass substrates. Our high throughput tool was able to identify the electrical properties of both resistive metal oxide thin film samples with high precision and accuracy. The scanning system enabled us to gain insight into transport mechanisms with novel compositions and to use those insights to make smart choices when choosing materials for our multilayer thin film all oxide photovoltaic cells. PMID:24880411

  2. Lunar magnetic field measurements, electrical conductivity calculations and thermal profile inferences

    NASA Technical Reports Server (NTRS)

    Colburn, D. S.

    1971-01-01

    Steady magnetic field measurements of magnitude 30 to 100 gamma on the lunar surface impose problems of interpretation when coupled with the nondetectability of a lunar field at 0.4 lunar radius altitude and the limb induced perturbations of the solar wind at the Explorer orbit. The lunar time-varying magnetic field clearly indicates the presence of eddy currents in the lunar interior and permits calculation of an electrical conductivity profile. The problem is complicated by the day-night asymmetry of the moon's electromagnetic environment, the possible presence of the transverse magnetic mode, and the variable wave directions of the driving function. The electrical conductivity is calculated to be low near the surface, rising to a peak of .006/ohm meter at 250 km, dropping steeply inwards to a value of about .00005/ohm meter, and then rising toward the interior. A transition at 250 km depth from a high conductivity to a low conductivity material is inferred, suggesting an olivine-like core at approximately 800 C, although other models are possible.

  3. A method to improve tree water use estimates by distinguishing sapwood from heartwood using Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Guyot, A.; Ostergaard, K.; Lenkopane, M.; Fan, J.; Lockington, D. A.

    2011-12-01

    Estimating whole-plant water use in trees requires reliable and accurate methods. Measuring sap velocity and extrapolating to tree water use is seen as the most commonly used. However, deducing the tree water use from sap velocity requires an estimate of the sapwood area. This estimate is the highest cause of uncertainty, and can reach more than 50 % of the uncertainty in the estimate of water use per day. Here, we investigate the possibility of using Electrical Resistivity Tomography to evaluate the sapwood area distribution in a plantation of Pinus elliottii. Electric resistivity tomographs of Pinus elliottii show a very typical pattern of electrical resistivity, which is highly correlated to sapwood and heartwood distribution. To identify the key factors controlling the variation of electrical resistivity, cross sections at breast height for ten trees have been monitored with electrical resistivity tomography. Trees have been cut down after the experiment to identify the heartwood/sapwood boundaries and to extract wood and sap samples. pH, electrolyte concentration and wood moisture content have then been analysed for these samples. Results show that the heartwood/sapwood patterns are highly correlated with electrical resistivity, and that the wood moisture content is the most influencing factor controlling the variability of the patterns. These results show that electric resistivity tomography could be used as a powerful tool to identify the sapwood area, and thus be used in combination with sapflow sensors to map tree water use at stand scale. However, if Pinus elliottii shows typical patterns, further work is needed to identify to see if there are species - specific characterictics as shown in previous works (, electrolyte gradients from the bark to the heartwood). Also, patterns of high resistivity in between needles positions, which are not correlated with either wood moisture content or sapwood, appear to be artifacts. Thus, inversion methods have also to be improved to take into account these measurements issues.

  4. Integrated Very Low Frequency EM, electrical resistivity and Geological studies on the Lanta Khola landslide, North Sikkim, India

    NASA Astrophysics Data System (ADS)

    Sharma, S. P.; Anbarasu, K.; Gupta, S.; Sengupta, A.

    2009-12-01

    Landslides are very common in high altitude Himalayan terrains. Major roads in the Himalayas are frequently blocked due to heavy landslides, and remain closed for long periods of time. Lanta Khola is one of the oldest landslides on the North Sikkim Highway (71.2 km north of the state capital of Sikkim, Gangtok) which is active since 1975. Rock types on either sides of the landslide are different (augen gneiss in the east and metapelitic schist in the west), and it is believed that the Main Central Thrust (MCT) passes through the slide zone. Permanent solutions to these landslides are required to keep the highway open. Delineation of subsurface structures below the landslide is very important in order to understand the triggers on slide activity. In such terrains, this can only be accomplished by geophysical survey. However, the steep slopes make it very difficult to find stretches of stable ground in these areas that are suitable for carrying out geophysical survey, especially electrical and electromagnetic. Very low frequency (VLF) electromagnetic survey is performed over Lanta Khola landside in North Sikkim Highway in order to depict the subsurface structure. Even though very limited numbers of VLF transmitters are available worldwide, it was possible to pick up the VLF signal from a number of VLF stations even in this high altitude mountainous terrain. VLF measurements along five profiles perpendicular to strike are recorded. High conducting zones are delineated from VLF observations. This conducting zone is also correlated with the low resistive zone delineated using gradient resistivity profiling. The anomalies confirm that there is a water saturated zone (‘soggy zone’) even in the subsurface of the slide, parallel to the geological gneiss-schist contact within the Lanta Khola slide. This indicates that the conductive feature correlates with a weak water-saturated debris layer that lies along, and is parallel to the geological contact. Resistive structures on either side of the landslide zone can thus be correlated with the stable ground. To minimize slide activity, it is therefore necessary to drain water from the soggy zone, since this zone appears to penetrate into the body of the slide

  5. Evaluation of Electrical Resistivity Tomography with Applications to Geologic CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Breen, Stephen James

    Field-scale studies have shown Electrical Resistivity Tomography (ERT) to be an effective tool for imaging resistivity anomalies and monitoring infiltration events in the near subsurface. ERT also shows potential for monitoring supercritical CO2 injections, despite deployment challenges in the deep subsurface. We present results from analog bench-scale experiments aimed at evaluating the ability of ERT to quantify the volume and spatial distribution of a resistive fluid injected into a brine-saturated porous medium. We injected measured volumes of air into translucent chambers filled with quartz sand, lined with electrodes, and saturated with a low resistivity salt solution. Between injections, a CCD camera captured high-resolution images, and an ERT data acquisition system scanned the chamber. Processing of the CCD images using quantitative visualization techniques resulted in high-resolution measurements of the spatial distribution and saturation of the injected gas. Direct comparison to inverted resistivity fields then provided a quantitative measure of the ability of ERT to estimate the total volume of injected gas and its spatial distribution within the chamber. Results show that ERT provided good estimates of the shape, size and location of the primary plume, but overestimated brine saturation within the plume and did not detect thin pathways of gas from the injection port or within the overlying capillary barrier. In one instance, ERT measurements also indicated a change in saturation within the primary plume that corresponded with observed leakage through the capillary barrier, demonstrating the potential utility of ERT as a leakage-monitoring tool. Repeated ERT scans during our experiments led to degradation in data quality that corresponded with an increase in measured contact resistance. Decreased data quality over time is clearly a concern for ERT implementation as a long-term monitoring strategy and deserves further study to quantify the responsible mechanisms.

  6. Modelling the electrical resistivity response to CO2 plumes generated in a laboratory, cylindrical sandbox

    NASA Astrophysics Data System (ADS)

    Kremer, T.; Maineult, A. J.; Binley, A.; Vieira, C.; Zamora, M.

    2012-12-01

    CO2 capture and storage into deep geological formations is one of the main solutions proposed to reduce the concentration of anthropic CO2 in the atmosphere. The monitoring of injection sites is a crucial issue to assess for the long term viability of CO2 storage. With the intention of detecting potential leakages, we are investigating the possibility of using electrical resistivity tomography (ERT) techniques to detect CO2 transfers in the shallow sub-surface. ERT measurements were performed during a CO2 injection in a cylindrical tank filled with Fontainebleau sand and saturated with water. Several measurements protocols were tested. The inversion of the resistances measured with the software R3T (Binley and Kemna (2005)) clearly showed that the CO2 injection induces significant changes in the resistivity distribution of the medium, and that ERT has a promising potential for the detection and survey of CO2 transfers through unconsolidated saturated media. We modeled this experiment using Matlab by building a 3D cellular automaton that describes the CO2 spreading, following the geometric and stochastic approach described by Selker et al. (2007). The CO2 circulation is described as independents, circular and continuous gas channels whose horizontal spread depends on a Gaussian probability law. From the channel distribution we define the corresponding gas concentration distribution and calculate the resistivity of the medium by applying Archie's law for unsaturated conditions. The forward modelling was performed with the software R3T to convert the resistivity distribution into resistances values, each corresponding to one of the electrode arrays used in the experimental measurements. Modelled and measured resistances show a good correlation, except for the electrode arrays located at the top or the bottom of the tank. We improved the precision of the model by considering the effects due to CO2 dissolution in the water which increases the conductivity of the saturated water in the vicinity of the plume. Finally, a special interest is given to the electrode configurations and measurement protocols. A numerical study was realized using R3T to assess the information that each electrode configuration can provide. We built a map of their sensitivity to resistivity changes. From these results, we studied the resolution of several electrode combinations by inverting the associated resistance in order to reduce the number of data really necessary to get a good imaging of the plume and thus accelerate the acquisition time.

  7. Expression Profile of Genes during Resistance Reversal in a Temephos Selected Strain of the Dengue Vector, Aedes aegypti

    PubMed Central

    Strode, Clare; de Melo-Santos, Maria; Magalhães, Tereza; Araújo, Ana; Ayres, Contancia

    2012-01-01

    Background The mosquito Aedes aegypti is one of the most important disease vectors because it transmits two major arboviruses, dengue and yellow fever, which cause significant global morbidity and mortality. Chemical insecticides form the cornerstone of vector control. The organophosphate temephos a larvicide recommended by WHO for controlling Ae. aegypti, however, resistance to this compound has been reported in many countries, including Brazil. Methodology/Principal Findings The aim of this study was to identify genes implicated in metabolic resistance in an Ae. aegypti temephos resistant strain, named RecR, through microarray analysis. We utilized a custom ‘Ae. aegypti detox chip’ and validated microarray data through RT-PCR comparing susceptible and resistant individuals. In addition, we analyzed gene expression in 4th instar larvae from a reversed susceptible strain (RecRev), exposed and unexposed to temephos. The results obtained revealed a set of 13 and 6 genes significantly over expressed in resistant adult mosquitoes and larvae, respectively. One of these genes, the cytochrome P450 CYP6N12, was up-regulated in both stages. RT-PCR confirmed the microarray results and, additionally, showed no difference in gene expression between temephos exposed and unexposed RecRev mosquitoes. This suggested that the differences in the transcript profiles among the strains are heritable due to a selection process and are not caused by immediate insecticide exposure. Reversal of temephos resistance was demonstrated and, importantly, there was a positive correlation between a decrease in the resistance ratio and an accompanying decrease in the expression levels of previously over expressed genes. Some of the genes identified here have also been implicated in metabolic resistance in other mosquito species and insecticide resistant populations of Ae. aegypti. Conclusions/Significance The identification of gene expression signatures associated to insecticide resistance and their suppression could greatly aid the development of improved strategies of vector control. PMID:22870187

  8. Phosphoproteomic profiling identifies focal adhesion kinase as a mediator of docetaxel resistance in castrate-resistant prostate cancer.

    PubMed

    Lee, Brian Y; Hochgräfe, Falko; Lin, Hui-Ming; Castillo, Lesley; Wu, Jianmin; Raftery, Mark J; Martin Shreeve, S; Horvath, Lisa G; Daly, Roger J

    2014-01-01

    Docetaxel remains the standard-of-care for men diagnosed with metastatic castrate-resistant prostate cancer (CRPC). However, only approximately 50% of patients benefit from treatment and all develop docetaxel-resistant disease. Here, we characterize global perturbations in tyrosine kinase signaling associated with docetaxel resistance and thereby develop a potential therapeutic strategy to reverse this phenotype. Using quantitative mass spectrometry-based phosphoproteomics, we identified that metastatic docetaxel-resistant prostate cancer cell lines (DU145-Rx and PC3-Rx) exhibit increased phosphorylation of focal adhesion kinase (FAK) on Y397 and Y576, in comparison with parental controls (DU145 and PC3, respectively). Bioinformatic analyses identified perturbations in pathways regulating focal adhesions and the actin cytoskeleton and in protein-protein interaction networks related to these pathways in docetaxel-resistant cells. Treatment with the FAK tyrosine kinase inhibitor (TKI) PF-00562271 reduced FAK phosphorylation in the resistant cells, but did not affect cell viability or Akt phosphorylation. Docetaxel administration reduced FAK and Akt phosphorylation, whereas cotreatment with PF-00562271 and docetaxel resulted in an additive attenuation of FAK and Akt phosphorylation and overcame the chemoresistant phenotype. The enhanced efficacy of cotreatment was due to increased autophagic cell death, rather than apoptosis. These data strongly support that enhanced FAK activation mediates chemoresistance in CRPC, and identify a potential clinical niche for FAK TKIs, where coadministration with docetaxel may be used in patients with CRPC to overcome chemoresistance. PMID:24194567

  9. ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY

    SciTech Connect

    RUCKER DF; FINK JB; LOKE MH; MYERS DA

    2009-11-05

    Highly industrialized areas pose significant challenges for surface based electrical resistivity characterization and monitoring due to the high degree of metallic infrastructure. The infrastructure is typically several orders of magnitude more conductive than the desired targets, preventing the geophysicist from obtaining a clear picture of the subsurface. These challenges may be minimized if steel-cased wells are used as long electrodes. We demonstrate a method of using long electrodes in a complex nuclear waste facility to monitor a simulated leak from an underground storage tank. The leak was simulated by injecting high conductivity fluid in a perforated well and the resistivity measurements were made before and after the leak test. The data were processed in four dimensions, where a regularization procedure was applied in both the time and space domains. The results showed a lowered resistivity feature develop south of the injection site. The time lapsed regularization parameter had a strong influence on the differences in inverted resistivity between the pre and post datasets, potentially making calibration of the results to specific hydrogeologic parameters difficult.

  10. Damage Characterization in SiC/SiC Composites using Electrical Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Craig E.; Xia, Zhenhai

    2011-01-01

    SiC/SiC ceramic matrix composites (CMCs) under creep-rupture loading accumulate damage by means of local matrix cracks that typically form near a stress concentration, such as a 90o fiber tow or large matrix pore, and grow over time. Such damage is difficult to detect through conventional techniques. Electrical resistance changes can be correlated with matrix cracking to provide a means of damage detection. Sylramic-iBN fiber-reinforced SiC composites with both melt infiltrated (MI) and chemical vapor infiltrated (CVI) matrix types are compared here. Results for both systems exhibit an increase in resistance prior to fracture, which can be detected either in situ or post-damage.

  11. Time-Lapse Electrical Resistivity Monitoring of the Remediation of a Saline Groundwater Plume

    NASA Astrophysics Data System (ADS)

    Hayley, K.; Bentlay, L. R.; Gharibi, M.

    2007-12-01

    Time-lapse electrical resistivity (ER) surveys are used to monitor the movement and remediation of a saline contaminant plume over the span of three years. Temperature is responsible for a large proportion of the observed ER changes. A temperature resistivity relationship is developed through laboratory testing on core from the site and analysis of petrophysical models. We present a protocol for removing the effects of temperature from ER difference images. Saturation changes also contribute to changes in the ER images. However, at this site, saturation is too spatially heterogeneous to apply a simple correction as was done with temperature. We show that the magnitude of the saturation changes are low and present an analysis of the uncertainty this introduces into the image interpretation. After accounting for temperature variations, we observe changes in the subsurface ER distribution that are consistent with depression focused recharge, solute flushing, and spatially variable effectiveness of the remediation program.

  12. Eradication of multidrug-resistant A. baumannii in burn wounds by antiseptic pulsed electric field

    PubMed Central

    Golberg, Alexander; Broelsch, G. Felix; Vecchio, Daniela; Khan, Saiqa; Hamblin, Michael R.; Austen, William G.; Sheridan, Robert L.; Yarmush, Martin L.

    2014-01-01

    Emerging bacterial resistance to multiple drugs is an increasing problem in burn wound management. New non-pharmacologic interventions are needed for burn wound disinfection. Here we report on a novel physical method for disinfection: antiseptic pulsed electric field (PEF) applied externally to the infected burns. In a mice model, we show that PEF can reduce the load of multidrug resistant Acinetobacter baumannii present in a full thickness burn wound by more than four orders of magnitude, as detected by bioluminescence imaging. Furthermore, using a finite element numerical model, we demonstrate that PEF provides non-thermal, homogeneous, full thickness treatment for the burn wound, thus, overcoming the limitation of treatment depth for many topical antimicrobials. These modeling tools and our in vivo results will be extremely useful for further translation of the PEF technology to the clinical setting, as they provide the essential elements for planning of electrode design and treatment protocol. PMID:25089285

  13. Effect of pressure on the electrical resistivity and magnetism in UPdSn

    SciTech Connect

    Honda, F.; Alsmadi, A. K. (Abdel Khaleq); Sechovsky, V. (Vladimir); Kamarad, J.; Nakotte, H. (Heinrich); Lacerda, A. H. (Alex H.); Mihalik, M.

    2002-01-01

    The electrical resistivity of a UPdSn single crystal exerted to various hydrostatic pressures was measured as a function of temperature and magnetic field. Clear anomalies in the temperature dependence of resistivity along the c-axis mark the magnetic phase transitions between paramagnetic and antiferromagnetic (AF) state at TN and the AF 1 -AF2 transition at T I .L arge negative magnetoresistance effects have been observed not only in the AF state as a result of the metamagnetic transition to canted structure ai B,, but also at temperatures far above TN. The latter result is attributed to the existence of AF correlations or short range AF ordering in the paramagnetic range. The value of TN increases with increasing applied pressure, whereas TI simultaneously decreases. It is also found that 13, decreases with increasing pressure. As a consequence, the stability range of the AF- 1 phase expands with applied pressure partially on account of the ground-state AF-2 phase.

  14. Epikarstic storage and doline structural characterization with time-lapse geophysics (seismic refraction & electrical resistivity)

    NASA Astrophysics Data System (ADS)

    Valois, R.; Galibert, P.; Guérin, R.; Mendes, M.; Plagnes, V.

    2011-12-01

    Karst formations are one of the most challenging environments in terms of groundwater, engineering and environmental issues. Geophysical methods can provide useful subsurface information in karst regions concerning groundwater vulnerability assessment, exploitation or hazard estimation. First, dolines are studied as preferential pathways for the protection of karstic aquifer in south France. Geophysics helps to characterize lateral and underground morphologies of such objects and is able to detect doline hidden by the soil cover too. Electrical resistivity and seismic refraction tomographies provide information about dolines filling and could help to propose a genesis scenario. Time-lapse resistivity measurements show that the studied doline is more vulnerable to infiltration on its sides than at its centre. The epikarst could be defined as a perched aquifer above the massive carbonate rocks; it constitutes a highly fractured zone, which water stock capacities. So, the epikarst was investigated with 3D seismic refraction and results show an important velocity anisotropy linked to the fracturing and weathering of the dolostone. The 3D model presents also some large heterogeneities: a corridor with highly weathered dolostone and an unweathered pinnacle. The corridor is probably situated on vertical joints, which have conducted aggressive water. The associated weathering with residual weathered-rock keeping its initial volume could create a "ghost-rock" corridor. So, the epikarst in the dolostones of the Causse du Larzac (France) seems to be composed by "ghost-rock" developed around a specific direction of fractures. Time-lapse electrical resistivity and seismic refraction velocity were carried out on this epikarst to observe the influence of water saturation on the measurements. The results show important variations for both seismic and electrical methods and are localized in the first 6 m: in the weathered zone. So, time-lapse measurements could more easily identify the storage of the epikarst and its bottom than one-time measurements; and with some calibration, semi-quantitative estimation of water saturation could be realized.

  15. Mild Electrical Stimulation with Heat Shock Ameliorates Insulin Resistance via Enhanced Insulin Signaling

    PubMed Central

    Sasaki, Kazunari; Adachi, Hironori; Suico, Mary Ann; Sekimoto, Erika; Matsuda, Tomoko; Shuto, Tsuyoshi; Araki, Eiichi; Kai, Hirofumi

    2008-01-01

    Low-intensity electrical current (or mild electrical stimulation; MES) influences signal transduction and activates phosphatidylinositol-3 kinase (PI3K)/Akt pathway. Because insulin resistance is characterized by a marked reduction in insulin-stimulated PI3K-mediated activation of Akt, we asked whether MES could increase Akt phosphorylation and ameliorate insulin resistance. In addition, it was also previously reported that heat shock protein 72 (Hsp72) alleviates hyperglycemia. Thus, we applied MES in combination with heat shock (HS) to in vitro and in vivo models of insulin resistance. Here we show that 10-min treatment with MES at 5 V (0.1 ms pulse duration) together with HS at 42°C increased the phosphorylation of insulin signaling molecules such as insulin receptor substrate (IRS) and Akt in HepG2 cells maintained in high-glucose medium. MES (12 V)+mild HS treatment of high fat-fed mice also increased the phosphorylation of insulin receptor ? subunit (IR?) and Akt in mice liver. In high fat-fed mice and db/db mice, MES+HS treatment for 10 min applied twice a week for 12–15 weeks significantly decreased fasting blood glucose and insulin levels and improved insulin sensitivity. The treated mice showed significantly lower weight of visceral and subcutaneous fat, a markedly improved fatty liver and decreased size of adipocytes. Our findings indicated that the combination of MES and HS alleviated insulin resistance and improved fat metabolism in diabetes mouse models, in part, by enhancing the insulin signaling pathway. PMID:19114996

  16. Electrical resistance of SrFeO2 at ultra high pressure

    NASA Astrophysics Data System (ADS)

    Kikuchi, Masayoshi; Kagayama, Tomoko; Shimizu, Katsuya; Kageyama, Hiroshi

    2015-03-01

    SrFeO2 shows antiferromagnetic and insulating order at ambient pressure. The crystal structure of SrFeO2 has 2-dementional FeO2 plate and is interested in because this is common structure of high temperature superconductor. SrFeO2 has M-I, magnetic and spin transition with applying pressure. If magnetism disappears and metallization occurs with applying pressure, SrFeO2 may show superconductivity because of the crystal structure, so we measured electrical resistance at high pressure up to 150 GPa and low temperature down to 100 mK.

  17. Critical roles of cappants on the electrical resistivity of Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, J.; Kaurav, N.; Ganesan, V.; Okram, Gunadhor S.

    2014-04-01

    We demonstrate here a very noteworthy nature of the critical roles of type of cappants, in addition to the particle size, on the electrical resistivity of compacted pellets of nickel nanoparticles (Ni-NPs) in the temperature range from 5 to 300 K that deviate significantly from highly conducting nature of a good metal yet without much deviation of the slopes. For this, face-centered cubic structured Ni-NPs of average particle size ranging from 18 to 33 nm were prepared using different polyol methods in the presence of various additional capping agents.

  18. Image Sticking Resistant Liquid Crystal Display Driven by Fringe Electric Field for Mobile Applicaitions

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    We propose image sticking resistant liquid crystal display (LCD) driven by fringe electric field for mobile application. For use of an alignment layer with polyamic acid (PA) type without cross link agent, impurity ions absorbed on the alignment layer easily discharge irrespective of liquid crystal (LC) because there is not any cross link agent which prevents discharging the ions, resulting in that image sticking easily disappears. For a panel with use of an alignment layer with polyimide (PI) type, time dependant flicker value is less than 2 dB and very steady while it is more than 10 dB and dramatically changes for a panel with the PA coated. From the result, we can know the PA coated panel without cross link agent has advantage in fast discharge of impurity ions when voltage is off, which is very favorable to an approach to image sticking free LCD driven by fringe electric field for mobile devices.

  19. Microstructure and electrical resistance evolution during sintering of a Ag nanoparticle paste

    NASA Astrophysics Data System (ADS)

    Scola, J.; Tassart, X.; Vilar, C.; Jomard, F.; Dumas, E.; Veniaminova, Y.; Boullay, P.; Gascoin, S.

    2015-04-01

    Silver nanoparticle pastes are promising materials for high temperature interconnection particularly above 400 °C. Reliability is a major concern in interconnection and it mainly depends on the behavior under the stress induced by thermal cycling. The joint microstructure is then a crucial parameter for reliability and determines the electrical, mechanical and thermal properties. Here, an investigation procedure is proposed to describe the microstructure of a joint and to monitor its evolution in real-time during the sintering. Combining electron and x-ray diffraction with electrical resistance measurement and secondary ion mass spectroscopy, our method is used on a sample made out of a home-made silver nanoparticle paste. The influence of the chemical composition of the paste on the microstructure is discussed as well as the compatibility of the paste for oxide interconnection.

  20. Skid resistance performance of asphalt wearing courses with electric arc furnace slag aggregates.

    PubMed

    Kehagia, Fotini

    2009-05-01

    Metallurgical slags are by-products of the iron and steel industry and are subdivided into blast furnace slag and steel slag according to the different steel-producing processes. In Greece, slags are mostly produced from steelmaking using the electric arc furnace process, and subsequently are either disposed in a random way or utilized by the cement industry. Steel slag has been recently used, worldwide, as hard aggregates in wearing courses in order to improve the skidding resistance of asphalt pavements. At the Highway Laboratory, Department of Civil Engineering of Aristotle University of Thessaloniki research has been carried out in the field of steel slags, and especially in electric arc furnace (EAF) slag, to evaluate their possible use in highway engineering. In this paper, the recent results of anti-skidding performance of steel slag aggregates in highway pavements are presented. PMID:19423603

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

    DOEpatents

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

    1996-02-27

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

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

    DOEpatents

    Ramirez, Abelardo L. (Pleasanton, CA); Cooper, John F. (Oakland, CA); Daily, William D. (Livermore, CA)

    1996-01-01

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

  3. High resolution electrical resistivity tomography of golf course greens irrigated with reclaimed wastewater: Hydrological approach

    NASA Astrophysics Data System (ADS)

    Tapias, Josefina C.; Lovera, Raúl; Himi, Mahjoub; Gallardo, Helena; Sendrós, Alexandre; Marguí, Eva; Queralt, Ignasi; Casas, Albert

    2014-05-01

    Actually, there are over 300 golf courses and more than three thousand licensed players in Spain. For this reason golf cannot be considered simply a hobby or a sport, but a very significant economic activity. Considered as one of the most rapidly expanding land-use and water demanding business in the Mediterranean, golf course development generates controversy. In the recent years there has been a considerable demand for golf courses to adopt environmentally sustainable strategies and particularly water authorities are forcing by law golf managers to irrigate with alternative water resources, mainly reclaimed wastewater. Watering practices must be based on soil properties that are characterized by samples removed from the different zones of the golf course and submitted to an accredited physical soil testing laboratory. Watering schedules are critical on greens with poor drainage or on greens with excessively high infiltration rates. The geophysical survey was conducted over the greens of the Girona Golf Club. Eighteen electrical resistivity tomographies were acquired using a mixed Wenner-Schlumberger configuration with electrodes placed 0.5 meter apart. Small stainless-steel nails were used as electrodes to avoid any damage in the fine turfgrass of greens The resistivity meter was set for systematically and automatically selects current electrodes and measurement electrodes to sample apparent resistivity values. Particle size analysis (PSA) has been performed on soil materials of any putting green. The PSA analysis has been composed of two distinct phases. The first has been the textural analysis of the soils for determining the content of sand, silt, and clay fraction via the use of a stack of sieves with decreasing sized openings from the top sieve to the bottom. Subsequently, the hydraulic conductivity of the substrates has been evaluated by means of Bredding and Hazen empirical relationships. The results of this research show that the electrical resistivity tomography is a non-invasive and cost-effective technique for high resolution characterizing the subsurface below golf course greens. The obtained models have provided detailed information on the lateral and vertical variability of each the subsurface and from an empirical correlation between the values of electrical resistivity and hydraulic permeability to assess the preferred areas of drainage that could pose in risk to the vulnerability of the underlying aquifers.

  4. 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

    NASA Astrophysics Data System (ADS)

    Viard, Jerome; Khantine-Langlois, Francoise

    While students' difficulties concerning the concepts of voltage and intensity have been investigated by many science education researchers, difficulties related to the concept of electrical resistance and circuit are less known. Some researchers in science education even state that students have no preconception about this concept before being taught. Our observations are in disagreement with this assumption. In the first section of this paper the main basic features of the difficulties of students confronted with the concept of electrical resistance are investigated. In the second section we discuss the nature of the electrical resistance concept in the light of Cassirer philosophy while in the third section we give an analysis of this concept going back to its origins in the nineteenth century. Finally, an analysis of the way this concept is taught in French high schools is presented and the first results of a experimentation using an alternative teaching strategy are briefly reported.c

  5. Trypanosoma evansi: in vivo and in vitro determination of trypanocide resistance profiles.

    PubMed

    Zhang, Z Q; Giroud, C; Baltz, T

    1993-12-01

    We have determined the in vivo and in vitro sensitivities to six common trypanocides of two groups of trypanosomes, (1) two Trypanosoma equiperdum clones and three Trypanosoma evansi clones originating from Asia, Latin America, and Africa; and (2) six laboratory-derived drug-resistant subclones from two of the T. evansi and one of the T. equiperdum clones. We found that (1) we could induce trypanocide resistance by successive passage through mice treated with subtherapeutic doses of drugs; (2) clones selected for resistance to berenil and cymelarsan are not cross-resistant to suramin; (3) clones resistant to berenil, cymelarsan, and suramin are more sensitive to quinapyramine in vivo than the parental clones; (4) berenil resistance is stable; (5) some berenil-resistant clones acquire resistance to cymelarsan; (6) in vivo resistance to isometamidium is not detectable in vitro; and (7) the in vitro sensitivities to berenil and cymelarsan of parental clones and their laboratory-derived resistant subclones generally agreed with the in vivo results. We conclude that with further refinement the in vitro assay procedure may be useful for rapid determination of the sensitivity of trypanosome isolates to some current drugs and for screening new trypanocides. Our data also raise the possibility that conventional treatment regimens should be reevaluated and support the presence of at least two drug-resistance mechanisms in T. evansi and T. equiperdum, single drug resistance (berenil), and cross-resistance (berenil and cymelarsan). PMID:8253152

  6. A One-Dimensional Model of the Electrical Resistance Sintering Process

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    In this work, a theoretical model for the processing technique usually known as electrical resistance sintering (ERS) under pressure is proposed and validated. This technique consists of the consolidation of a metallic powder mass under compression by means of a high-intensity electrical current that passes through the aggregate. The electrical current heats the powder mass by the Joule effect. The model is numerically solved by the finite differential method, in which the added difficulty of the thermal-mechanical coupling of the process has been taken into account. To simplify the numerical resolution, a one-dimensional scheme has been considered for both the powder densification mechanical problem and the heat generation and transmission problem. Furthermore, the theoretical predictions obtained after solving the model are compared with the data recorded by the ERS equipment sensors during electrical consolidation experiments with iron and titanium powders. The reasonable agreement between the theoretical and experimental curves suggests that the model, despite its simplifications, reproduces the main characteristics of the process.

  7. Applications of electrical resistivity imaging for characterizing groundwater-surface water interactions from local to regional scales

    NASA Astrophysics Data System (ADS)

    Cardenas, M. B.; Befus, K. M.; Zamora, P. B.; Ong, J.; Zlotnik, V. A.; Cook, P. L.; Tait, D. R.; Erler, D.; Santos, I. R.; Siringan, F. P.

    2012-12-01

    Surface water (SW) and groundwater (GW) interact across multiple spatial and temporal scales and their interaction is important for ecological and biogeochemical functions. The mixing of GW and SW has been challenging to simultaneously map with sufficient detail and coverage. Fortunately, ambient differences in salinity of waters occupying geologic formations and sediment are an ideal target for electrical resistivity imaging (ERI). We present examples of the application of ERI for mapping GW discharge and for understanding GW-SW interactions at: (1) a large regulated river, (2) neighboring lakes with differing salinity, (3) fringing coral reefs and lagoons, (4) beaches, and (5) estuaries. In all these cases, the ER tomograms were critical for improving conceptual understanding of GW-SW interactions. At the Lower Colorado River in Austin, Texas (USA), time-lapse ERI was conducted across a 12-hour dam-release cycle when the river stage varied by 0.7 m. Using temporal variability in electrical resistivity (ER) signatures, we identified a shallow well-flushed hyporheic zone, a transition zone where SW and GW mix, and a stable deep zone hosting only GW. In alkaline lakes in the Nebraska Sand Hills (Nebraska, USA), ER surveys using boat-towed cables allowed for mapping the 3D electrical structure underneath the lake. The tomograms were used to distinguish flow-through lakes, which have decreasing subsurface ER from GW inflow to outflow area, from pure GW discharge lakes, which have uniformly stratified increasing-with-depth ER profiles. Moreover, GW plumes in both discharge and recharge zones were clearly outlined underneath the lake. More than 30 km of ER profiles collected via boat-towed surveys over a fringing coral reef in the Philippines identified areas of high ER within the reef that coincide with resistive zones in the seawater. Analysis of 222Rn of bottom waters and vertical conductivity-temperature-depth measurements show the persistence of fresh GW input into the ocean where low salinity and high 222Rn areas coincided with high ER areas. In Muri Lagoon in Rarotonga Island of the Cook Islands, boat-towed ER surveys similarly showed areas underneath the lagoon that have groundwater that is fresher than seawater. Likewise, there was 222Rn high concentrations throughout the lagoon. Closer to shore, ER surveys using fixed electrodes showed complex 3D mixing processes between seawater and terrestrial-sourced fresh groundwater in beach sediment. Lastly, both boat-towed and fixed surveys across the salt wedge of Werribee Estuary west of Melbourne, Australia, outlined the estuarine salt wedge and its relationship with and effect on fresh and nutrient-laden groundwater discharging to the estuary. The examples discussed illustrate that ERI is a powerful and convenient tool for mapping GW discharge and GW-SW interactions across different scales and diverse environments.

  8. Minimizing State-of-Health Degradation in Hybrid Electrical Energy Storage Systems with Arbitrary Source and Load Profiles

    E-print Network

    Pedram, Massoud

    Source and Load Profiles Abstract--Hybrid electrical energy storage (HEES) systems consisting in the HEES systems while simultaneously improving the overall cycle efficiency. The SoH- aware charge systems. Hybrid EES (HEES) systems consisting of heterogeneous EES elements are proposed to exploit

  9. Lou\\/C Obesity-resistant Rat Exhibits Hyperactivity, Hypermetabolism, Alterations in White Adipose Tissue Cellularity, and Lipid Tissue Profiles

    Microsoft Academic Search

    Christophe Soulage; Bader Zarrouki; Anisio Francesco Soares; Michel Lagarde; Alain Geloen

    2007-01-01

    Lou\\/C obesity-resistant rat constitutes an original model to understand the phenomena of overweight and obesity. The aim of the present study was to identify metabolic causes for the outstanding leanness of Lou\\/C rat. To this end, the meta- bolic profiles (food intake, energy expenditure, and physical activity) and the cellular characteristics of white adipose tis- sue (lipogenesis, lipolysis, cellularity, and

  10. Differential gene expression profiling of Listeria monocytogenes in Cacciatore and Felino salami to reveal potential stress resistance biomarkers.

    PubMed

    Mataragas, M; Rovetto, F; Bellio, A; Alessandria, V; Rantsiou, K; Decastelli, L; Cocolin, L

    2015-04-01

    The current study reports a) the in situ transcriptional profiles of Listeria monocytogenes in response to fermented sausage stress and b) an approach in which in situ RT-qPCR data have been combined with advanced statistical techniques to discover potential stress resistance or cell viability biomarkers. Gene expression profiling of the pathogen has been investigated using RT-qPCR to understand how L. monocytogenes responds to the conditions encountered during the fermentation and ripening of sausages. A cocktail of five L. monocytogenes strains was inoculated into the batter of Cacciatore and Felino sausages. The RT-qPCR data showed that the acidic and osmotic stress-related genes were up-regulated. The transcripts of the lmo0669 gene increased during the fermentation and ripening of Cacciatore, whereas gbuA and lmo1421 were up-regulated during the ripening of Felino and Cacciatore, respectively. sigB expression was induced in both sausages throughout the whole process. Finally, the virulence-related gene prfA was down-regulated during the fermentation of Cacciatore. The multivariate gene expression profiling analysis suggested that sigB and lmo1421 or sigB and gbuA could be used as different types of stress resistance biomarkers to track, for example, stress resistance or cell viability in fermented sausages with short (Cacciatore) or long (Felino) maturation times, respectively. PMID:25475310

  11. Electrical resistivity surveys for gold-bearing veins in the Yongjang mine, Korea

    NASA Astrophysics Data System (ADS)

    Park, Jong-Oh; You, Young-June; Kim, Hee Joon

    2009-03-01

    The Yongjang mine is an Au-Ag deposit near Masan, located at the southernmost tip of the Korean Peninsula. The deposit lies within Cretaceous sedimentary rocks and contains many quartz veins which contain elements such as gold and silver, and sulfides. In the mine, the Yongjang, En and Ansan quartz veins have been found to be gold bearing. These veins have thicknesses of 2-40 cm and extents of 100-260 m. Electrical resistivity surveys were conducted to clarify the location of gold deposits at both prospect and detailed scales. Apparent resistivity data were collected with a dipole-dipole array on the ground surface and in boreholes, and with a pole-dipole array for surface-to-borehole surveys. The datasets derived from three-dimensional inversion of apparent resistivities are quite effective at delineating the geological structures related to gold-bearing quartz veins. These appear as a low-resistivity anomaly because almost all of the gold mineralization occurs in fractured areas associated with faults or shear zones. The surface-to-borehole survey had better resolution than the surface dipole-dipole survey when imaging gold-bearing quartz veins. The low-resistivity anomalies indicating the Yongjang and Ansan veins extend nearly vertically to sea level and dip steeply below sea level. They run NW-SE parallel to each other at a distance of about 70 m. The En vein is imaged near the Yonjang vein with a strike direction of N60°-70° W and a dip angle of about 45°.

  12. Permafrost Changes along the Alaska Highway Corridor, Southern Yukon, from Ground Temperature Measurements and DC Electrical Resistivity Tomography

    NASA Astrophysics Data System (ADS)

    Duguay, M. A.; Lewkowicz, A. G.; Smith, S.

    2011-12-01

    A natural gas pipeline running across permafrost terrain from Prudhoe Bay, Alaska, through Canada to US markets was first proposed more than 30 years ago. In the intervening period, mean annual air temperatures in the region have risen by 0.5-1.0°C and it is probable that the ground has also warmed. Renewed interest in the pipeline has meant that information on permafrost and geotechnical conditions within the Alaska Highway Corridor of the southern Yukon must be updated for engineering design and the assessment of environmental impacts. To accomplish this goal, results from 1977-1981 drilling and ground temperature monitoring programs within the proposed pipeline corridor were used in combination with air photo analysis to select sites potentially sensitive to climate change. The sites are distributed across the extensive and sporadic discontinuous permafrost zones over a distance of 475 km between Beaver Creek and Whitehorse. To date, 11 targeted boreholes with permafrost have been found and cased to permit renewed ground temperature monitoring. By the end of summer 2011, it is expected that another 7 will have been instrumented. Measurable temperature increases relative to the 1970s are expected, except where values were previously just below 0°C. In the latter case, if the sites are still in permafrost, latent heat effects may have substantially moderated the temperature increase. Electrical resistivity tomography surveys are also being conducted to characterize the local permafrost distribution and geotechnical conditions. These 2D resistivity profiles will be used with the ground temperatures to examine current conditions and response to climate change and vegetation disturbance.

  13. Application of 3D electrical resistivity imaging in an underground potash mine Robert A. Eso and Douglas W. Oldenburg, University of British ColumbiaGeophysical Inversion Facility

    E-print Network

    Oldenburg, Douglas W.

    Application of 3D electrical resistivity imaging in an underground potash mine Robert A. Eso- ground mining environments. The electrical conductivity contrast be- tween dry and wet salt make it possible to explore for water infiltrated areas in underground salt mines using electrical resistivity

  14. Computational Analysis of HIV-1 Resistance Based on Gene Expression Profiles and the Virus-Host Interaction Network

    PubMed Central

    Huang, Tao; Xu, Zhongping; Chen, Lei; Cai, Yu-Dong; Kong, Xiangyin

    2011-01-01

    A very small proportion of people remain negative for HIV infection after repeated HIV-1 viral exposure, which is called HIV-1 resistance. Understanding the mechanism of HIV-1 resistance is important for the development of HIV-1 vaccines and Acquired Immune Deficiency Syndrome (AIDS) therapies. In this study, we analyzed the gene expression profiles of CD4+ T cells from HIV-1-resistant individuals and HIV-susceptible individuals. One hundred eighty-five discriminative HIV-1 resistance genes were identified using the Minimum Redundancy-Maximum Relevance (mRMR) and Incremental Feature Selection (IFS) methods. The virus protein target enrichment analysis of the 185 HIV-1 resistance genes suggested that the HIV-1 protein nef might play an important role in HIV-1 infection. Moreover, we identified 29 infection information exchanger genes from the 185 HIV-1 resistance genes based on a virus-host interaction network analysis. The infection information exchanger genes are located on the shortest paths between virus-targeted proteins and are important for the coordination of virus infection. These proteins may be useful targets for AIDS prevention or therapy, as intervention in these pathways could disrupt communication with virus-targeted proteins and HIV-1 infection. PMID:21394196

  15. Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang

    2012-09-01

    In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of ? and t were obtained.

  16. Electric-resistance furnace for melting ash from municipal solid waste incinerator

    SciTech Connect

    Nakao, Tsuyoshi; Nakahara, Keisuke [NKK Corp., Kawasaki, Kanagawa (Japan); Akashi, Tetsuo [NKK Corp., Yokohama, Kanagawa (Japan). Environmental Plant Engineering Dept.

    1997-12-31

    Existing landfill capacity is dwindling in Japan and it is difficult to find new landfill sites because of strong opposition from residents. Under the Waste Disposal and Public Cleaning Law in 1991 in Japan, fly ashes from municipal solid waste (MSW) incinerator have to be treated by one of the four methods: (1) vitrification, (2) solidification by cement, (3) stabilization using chemical agents, or (4) extraction with acid or other solvent. In these four technologies, the vitrification technology has some advantages: decreasing ash volume which can solve the landfill problem, de-taxiing ash, and utilization of its products from residues. NKK has developed an electric resistance furnace for melting MSW incineration residues and built a demonstration plant (24t/d). The performance test results showed as follows; (1) Si, Al, and Ca tended to become the molten slag. Cu, P, and Fe tended to become the molten metal. Pb, Zn, and Cd tended to become the molten fly ash. (2) HCl from the slag resistance electric furnace was 60 ppm and very low compared with other melting systems. (3) Decomposition rate of dioxins was 99 % in the melting furnace. (4) Concentration of heavy metals in the molten slag was low and leaching of heavy metals was below Japanese regulation.

  17. Monitoring freshwater salinization in analog transport models by time-lapse electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Wagner, Florian M.; Möller, Marcus; Schmidt-Hattenberger, Cornelia; Kempka, Thomas; Maurer, Hansruedi

    2013-02-01

    Deep saline aquifers are target formations both for the geological storage of carbon dioxide as well as for geothermal applications. High pressure gradients, resulting from fluid or gas injection processes, provide a potential driving force for the displacement of native formation waters, implicating a potential salinization of shallow freshwater resources. Geoelectrical monitoring techniques are sensitive to compositional changes of groundwater resources, and hence capable to detect salinization processes at an early stage. In this context, numerical simulations and analog modeling can provide a valuable contribution by identifying probable salinization scenarios, and thereby guiding an optimum sensor network layout within the scope of an early warning system. In this study, coupled numerical flow and transport simulations of a laterally uniform salinization scenario were carried out and used to support a subsequent realization in a laboratory sandbox model. During the experiment, electrical resistivity tomography (ERT) was applied in a practical surface-borehole setup in order to determine the spatio-temporal variations of electrical properties influenced by saltwater intrusion. Inversion results of different electrode configurations were evaluated and compared to numerical simulations. With regard to surface-borehole measurements, good results were obtained using crossed bipoles, while regular bipole measurements were more susceptible to noise. Within the scope of a single-hole tomography, the underlying resistivity distribution was best reproduced using the Wenner configuration, which was substantiated by synthetic modeling.

  18. Fully coupled hydrogeophysical inversion of a laboratory salt tracer experiment monitored by electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Pollock, Davina; Cirpka, Olaf A.

    2012-01-01

    We perform a salt tracer experiment, monitored by time-lapse electrical resistivity tomography, in a quasi-two-dimensional sandbox with the aim of determining the hydraulic conductivity distribution in the domain. We use sodium chloride as a tracer, together with cochineal red for visual monitoring. The time series of observed resistance for each electrode configuration is characterized by its temporal moments. We invert the mean arrival time of electrical potential perturbations and a few steady state hydraulic head measurements using the fully coupled hydrogeophysical approach recently introduced by Pollock and Cirpka (2010). This is the first application of the approach to experimental data. The results obtained show a reasonable agreement between the estimated hydraulic conductivity field and the pattern of the actual sandbox filling. Using this estimation, a transient simulation is performed to compute the propagation of the salt tracer plume through the sandbox. The latter is compared to pictures taken during the experiment. These results show an even better agreement, indicating that the lenses of different sand types are not entirely homogeneous and some unexpected preferential flow paths are present. We conclude that temporal moments of potential perturbations obtained during salt tracer tests provide a good basis for inferring the hydraulic conductivity distribution by fully coupled hydrogeophysical inversion.

  19. Tabletop Models for Electrical and Electromagnetic Geophysics.

    ERIC Educational Resources Information Center

    Young, Charles T.

    2002-01-01

    Details the use of tabletop models that demonstrate concepts in direct current electrical resistivity, self-potential, and electromagnetic geophysical models. Explains how data profiles of the models are obtained. (DDR)

  20. The in vitro assay profile of macrocyclic lactone resistance in three species of sheep trichostrongyloids?

    PubMed Central

    Demeler, Janina; Gill, Jennifer H.; von Samson-Himmelstjerna, Georg; Sangster, Nicholas C.

    2013-01-01

    Anthelmintic resistance has emerged as an important problem in animal industries. Understanding resistance mechanisms, especially against macrocyclic lactones (MLs), is the first step in developing better diagnostic tools. Effects of several MLs including ivermectins and milbemycins were tested using two well established in vitro assays: the larval development assay (LDA) and the larval migration inhibition assay (LMIA). These were performed on free-living stages of susceptible and ML-resistant isolates of three trichostrongyloid nematode species of sheep. In general, dose response curves shifted to the right in the resistant isolates. Data showed that resistance was present to ivermectin and its two components suggesting that both components contribute to action and resistance. There were no consistent patterns of potency and resistance of the tested substances for the different isolates in the LDA except that moxidectin (MOX) tended to have lower resistance ratios than ivermectin (IVM). MOX was the most potent inhibitor in the LMIA in susceptible Haemonchus contortus while being less potent in Trichostrongylus colubriformis and particularly in Ostertagia circumcincta. MOX showed high resistance ratios in the LMIA in all three species. Based on these results, resistance to MOX has unique characteristics and the LMIA may perform better in detecting resistance to MOX in these parasite species. PMID:24533300

  1. The in vitro assay profile of macrocyclic lactone resistance in three species of sheep trichostrongyloids.

    PubMed

    Demeler, Janina; Gill, Jennifer H; von Samson-Himmelstjerna, Georg; Sangster, Nicholas C

    2013-12-01

    Anthelmintic resistance has emerged as an important problem in animal industries. Understanding resistance mechanisms, especially against macrocyclic lactones (MLs), is the first step in developing better diagnostic tools. Effects of several MLs including ivermectins and milbemycins were tested using two well established in vitro assays: the larval development assay (LDA) and the larval migration inhibition assay (LMIA). These were performed on free-living stages of susceptible and ML-resistant isolates of three trichostrongyloid nematode species of sheep. In general, dose response curves shifted to the right in the resistant isolates. Data showed that resistance was present to ivermectin and its two components suggesting that both components contribute to action and resistance. There were no consistent patterns of potency and resistance of the tested substances for the different isolates in the LDA except that moxidectin (MOX) tended to have lower resistance ratios than ivermectin (IVM). MOX was the most potent inhibitor in the LMIA in susceptible Haemonchus contortus while being less potent in Trichostrongylus colubriformis and particularly in Ostertagia circumcincta. MOX showed high resistance ratios in the LMIA in all three species. Based on these results, resistance to MOX has unique characteristics and the LMIA may perform better in detecting resistance to MOX in these parasite species. PMID:24533300

  2. Discovery of genes implicated in whirling disease infection and resistance in rainbow trout using genome-wide expression profiling

    PubMed Central

    Baerwald, Melinda R; Welsh, Amy B; Hedrick, Ronald P; May, Bernie

    2008-01-01

    Background Whirling disease, caused by the pathogen Myxobolus cerebralis, afflicts several salmonid species. Rainbow trout are particularly susceptible and may suffer high mortality rates. The disease is persistent and spreading in hatcheries and natural waters of several countries, including the U.S.A., and the economic losses attributed to whirling disease are substantial. In this study, genome-wide expression profiling using cDNA microarrays was conducted for resistant Hofer and susceptible Trout Lodge rainbow trout strains following pathogen exposure with the primary objective of identifying specific genes implicated in whirling disease resistance. Results Several genes were significantly up-regulated in skin following pathogen exposure for both the resistant and susceptible rainbow trout strains. For both strains, response to infection appears to be linked with the interferon system. Expression profiles for three genes identified with microarrays were confirmed with qRT-PCR. Ubiquitin-like protein 1 was up-regulated over 100 fold and interferon regulating factor 1 was up-regulated over 15 fold following pathogen exposure for both strains. Expression of metallothionein B, which has known roles in inflammation and immune response, was up-regulated over 5 fold in the resistant Hofer strain but was unchanged in the susceptible Trout Lodge strain following pathogen exposure. Conclusion The present study has provided an initial view into the genetic basis underlying immune response and resistance of rainbow trout to the whirling disease parasite. The identified genes have allowed us to gain insight into the molecular mechanisms implicated in salmonid immune response and resistance to whirling disease infection. PMID:18218127

  3. Geophysical model of geological discontinuities in a granitic aquifer: Analyzing small scale variability of electrical resistivity for groundwater occurrences

    NASA Astrophysics Data System (ADS)

    Chandra, Subash; Dewandel, Benoit; Dutta, Sushobhan; Ahmed, Shakeel

    2010-08-01

    Geological discontinuities such as quartz reef, a common geological feature in hard rock terrain occurring as an intrusive body, has been investigated using geophysical methods in order to explore and map the potential aquifer. Electrical resistivity response of quartz reef intrusive in granite host rock has been studied using synthetic simulation for different physical conditions such as: (1) fresh intrusive body with no alteration at contacts, (2) fresh intrusive body with weathered-fissured contacts, and (3) also fissured intrusive body with weathered-fissured contacts. Electrical Resistivity Tomography (ERT) was carried out traversing across and along the quartz reef at Kothur village, Hyderabad, India. Based on the ERT results 11 bore wells have been drilled followed by yield measurement, litholog collection, and electrical resistivity logging. Geomorphology, ERT images, lithologs, resistivity logs and yield of the wells are found corroborating with each other. Deepening of the weathering fronts are confirmed along the contacts of the quartz reef and granite, which may qualify suitable sites for groundwater occurrence. This has been finally validated from the drilling results, where high yielding (18 m 3/h) bore well found at low resistive zones within the quartz reef. The study has helped in preparing a 2D section of the structural set up of the quartz reef in granite host medium and finally revealed that the quartz reefs may provide potential groundwater zone. The distribution of electrical resistivity of the geological discontinuity is useful providing promising input to the groundwater flow model particularly in three dimensional.

  4. Electrical Resistance of SiC/SiC Ceramic Matrix Composites for Damage Detection and Life-Prediction

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Morscher, Gregory; Xia, Zhenhai

    2009-01-01

    Ceramic matrix composites (CMC) are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems due to their low density high thermal conductivity. The employment of these materials in such applications is limited by the ability to accurately monitor and predict damage evolution. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. CMC is a multifunctional material in which the damage is coupled with the material s electrical resistance, providing the possibility of real-time information about the damage state through monitoring of resistance. Here, resistance measurement of SiC/SiC composites under mechanical load at both room temperature monotonic and high temperature creep conditions, coupled with a modal acoustic emission technique, can relate the effects of temperature, strain, matrix cracks, fiber breaks, and oxidation to the change in electrical resistance. A multiscale model can in turn be developed for life prediction of in-service composites, based on electrical resistance methods. Results of tensile mechanical testing of SiC/SiC composites at room and high temperatures will be discussed. Data relating electrical resistivity to composite constituent content, fiber architecture, temperature, matrix crack formation, and oxidation will be explained, along with progress in modeling such properties.

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

    SciTech Connect

    Buettner, M.; Daily, B.; Ramirez, A.

    1997-07-03

    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 capable of collecting a full data set in under 1 hour, allowing for nearly real time sampling of the infiltration. The infiltration was conducted in two phases. During the first phase, water was introduced into the asphalt-concrete (AC) layers at a slow rate of about 8 ml per hour for a period of about 6 days. In the second phase, water was introduced into the asphalt-treated-permeable base (ATPB) layer at a more rapid rate of about 100 ml/h for about 2 days. The ERT images show that water introduced into the upper AC layers shows up as a decrease in resistivity which grows with time. The images also appear to show that when water moves into the layers below the ATPB, the resistivity increases; an unexpected result. There are some indications that the water moved laterally as well as down into the deeper ATPB and the aggregate base. The images also show that when water is introduced directly into the ATPB and aggregate layer, the water moves into the the underlying materials much more quickly.

  6. Electrical resistivity and thermopower of Y1-xPrxCo2 Compounds

    NASA Astrophysics Data System (ADS)

    Uchima, K.; Teruya, A.; Takaesu, Y.; Akamine, H.; Kakihana, M.; Tomori, K.; Uejo, T.; Nakamura, A.; Hedo, M.; Nakama, T.; Yagasaki, K.; Burkov, A. T.

    2015-03-01

    Electrical resistivity ? and thermopower S of the pseudo-binary compounds of Y1-xPrxCo2 have been measured in the temperature range between 2 and 300 K under magnetic fields up to 10 T, together with the pressure measurements of ? and S in Y0.4Pr0.6Co2. The Curie temperature decreases with decreasing x, and vanishes at the critical composition xc ? 0.4, where the residual resistivity attains a maximum value. The Curie temperature and the residual resistivity of Y0.4Pr0.6Co2 show the same pressure dependence as those of the heavy-rare-earth based compounds. These behaviors of ? and S indicate the inhomogeneous distribution of the Co 3d magnetization. The magnetoresistance of the light-rare earth Y1-xPrxCo2 system is negative in the whole range of x, except for x = 0 and 1, which is a characteristic behavior related with magnetic state and magnitude of the effective field acting on the Co 3d subsystem.

  7. Transient mechanical and electrical properties of uncooled resistive microbolometer focal plane arrays

    NASA Astrophysics Data System (ADS)

    Li, Biao; Huang, Shusen; Zhang, Xin

    2004-10-01

    Recent advances in MEMS and focal plane array (FPA) technologies have led to the development of manufacturing microbolometers monolithically on a readout integrated circuit (ROIC). In this work, both numerical and finite element methods were performed to simulate the transient electrical and mechanical responses of resistive microbolometer FPAs made by several TCR (thermal coefficient of resistance) materials including a-Si, VOx and semiconducting YBCO. Numerical simulation shows that the pulsed bias readout mode in resistive microbolometer FPAs causes a non-steady-state of the system during the operation. As a result, NETD decreases with the increasing pulse width. In FPAs, the array size, frame rate, ROIC and mechanical reliability set the up-limit to the pulse width. The transient mechanical response for three microbolometer configurations was investigated using finite element modeling. The biased pulse results in membrane bending along the z-axis for the symmetric extended configuration (Type I), or twisting in three axes for the asymmetric extended configuration (Type II) due to the constraint force from the supporting arms. The square configuration (Type III) exhibits the smallest deformation and minimum shear stress at the sharp geometries. a-Si microbolometer generates higher shear stress than other microbolometers with the same square configuration.

  8. Oxidation Resistant, Cr Retaining, Electrically Conductive Coatings on Metallic Alloys for SOFC Interconnects

    SciTech Connect

    Vladimir Gorokhovsky

    2008-03-31

    This report describes significant results from an on-going, collaborative effort to enable the use of inexpensive metallic alloys as interconnects in planar solid oxide fuel cells (SOFCs) through the use of advanced coating technologies. Arcomac Surface Engineering, LLC, under the leadership of Dr. Vladimir Gorokhovsky, is investigating filtered-arc and filtered-arc plasma-assisted hybrid coating deposition technologies to promote oxidation resistance, eliminate Cr volatility, and stabilize the electrical conductivity of both standard and specialty steel alloys of interest for SOFC metallic interconnect (IC) applications. Arcomac has successfully developed technologies and processes to deposit coatings with excellent adhesion, which have demonstrated a substantial increase in high temperature oxidation resistance, stabilization of low Area Specific Resistance values and significantly decrease Cr volatility. An extensive matrix of deposition processes, coating compositions and architectures was evaluated. Technical performance of coated and uncoated sample coupons during exposures to SOFC interconnect-relevant conditions is discussed, and promising future directions are considered. Cost analyses have been prepared based on assessment of plasma processing parameters, which demonstrate the feasibility of the proposed surface engineering process for SOFC metallic IC applications.

  9. Good electrical contacts for high resistivity (Cd,Mn)Te crystals

    SciTech Connect

    Witkowska-Baran,M.; Mycielski, A.; Kochanowska, D.; Szadkowski, A. J.; Jakiela, r.; Witkowska, B.; Kaliszek, W.; Domagala, J.; Lusakowska, E.; Domukhovski, V.; Dybko, K.; Cui, Y.; James, R. B.

    2008-10-19

    We consider that semi-insulating (Cd,Mn)Te crystals may well successfully replace the commonly used (Cd,Zn)Te crystals as a material for manufacturing large-area X- and gamma-ray detectors. The Bridgman growth method yields good quality and high-resistivity (10{sup 9}-10{sup 10} {Omega}-cm) crystals of (Cd,Mn)Te:V. Doping with vanadium ({approx} 10{sup 16} cm{sup -3}), which acts as a compensating agent, and annealing in cadmium vapors, which reduces the number of cadmium vacancies in the as-grown crystal, ensure this high resistivity. Detector applications of the crystals require satisfactory electrical contacts. Hence, we explored techniques of ensuring good electrical contacts to semi-insulating (Cd,Mn)Te crystals. Our findings are reported here. Before depositing the contact layers, we prepared an 'epi-ready' surface of the crystal platelet by a procedure described earlier for various tellurium-based II-VI compound crystals. A molecular beam epitaxy (MBE) apparatus was used to deposit various types of contact layers: Monocrystalline semiconductor layers, amorphous- and nanocrystalline semiconductor layers, and metal layers were studied. We employed ZnTe heavily doped ({approx} 10{sup 18} cm{sup -3}) with Sb, and CdTe heavily doped ({approx} 10{sup 17} cm{sup -3}) with In as the semiconductors to create contact layers that subsequently enable good contact (with a narrow, tunneling barrier) to the Au layer that usually is applied as the top contact layer. We describe and discuss the technology and some properties of the electrical contacts to semi-insulating (Cd,Mn)Te.

  10. Comparison of HIV-1 resistance profiles in plasma RNA versus PBMC DNA in heavily treated patients in Honduras, a resource-limited country.

    PubMed

    Diallo, Karidia; Murillo, Wendy E; de Rivera, Ivette Lorenzana; Albert, Jan; Zhou, Zhiyong; Nkengasong, John; Zhang, Guoqing; Sabatier, Jennifer F; Yang, Chunfu

    2012-01-01

    The World Health Organization currently does not recommend the use of dried blood spot specimens for drug resistance testing in patients undergoing antiretroviral therapy (ART). Therefore, HIV-1 resistance testing using peripheral blood mononuclear cells (PBMCs) may be of value in resource-limited settings. We compared genotypic resistance profiles in plasma and PBMCs from patients failing ART in two cities of Honduras (Tegucigalpa and San Pedro Sula), a resource-limited country. One hundred patients failing ART were randomly selected from a longitudinal patient monitoring cohort. Plasma and PBMC samples without patient identifier were used for genotypic resistance testing. Sequence data were analyzed, resistance profiles were determined and compared using Stanford HIV Drug Resistance Database algorithm. Specimens with concordant resistance profiles between the two compartments were 88% (95% CI: 80.3% - 94.5 %). Nine specimens (12%, 95% CI: 6.5% - 21.3%) had discordant resistance profiles of clinical significance. Logistic regression analyses indicated that patients on triple therapy were 17.24 times more likely to have concordant drug resistance profile than those on non-triple therapies (OR=17.24, 95% CI: 3.48, 83.33), while patients with increasing number of regimens and years on ART have a decreased rate of concordance (OR = 0.59, 95% CI: 0.32, 1.09 and OR = 0.62, 95% CI: 0.43, 0.88), respectively, than those with less number of regimens and years on ART. Our results show high level of concordance between plasma and PBMC resistance profiles, indicating the possibility of using PBMCs for drug resistance testing in resources-limited settings. PMID:22493752

  11. Characterization of a dismissed landfill via electrical resistivity tomography and mise-à-la-masse method

    NASA Astrophysics Data System (ADS)

    De Carlo, Lorenzo; Perri, Maria Teresa; Caputo, Maria Clementina; Deiana, Rita; Vurro, Michele; Cassiani, Giorgio

    2013-11-01

    Electrical resistivity methods are widely used for environmental applications, and they are particularly useful for the characterization and monitoring of sites where the presence of contamination requires a thorough understanding of the location and movement of water, that can act as a carrier of solutes. One such application is landfill studies, where the strong electrical contrasts between waste, leachate and surrounding formations make electrical methods a nearly ideal tool for investigation. In spite of the advantages, however, electrical investigation of landfills poses also challenges, both logistical and interpretational. This paper presents the results of a study conducted on a dismissed landfill, close to the city of Corigliano d'Otranto, in the Apulia region (Southern Italy). The landfill is located in an abandoned quarry, that was subsequently re-utilized about thirty years ago as a site for urban waste disposal. The waste was thought to be more than 20 m thick, and the landfill bottom was expected to be confined with an HDPE (high-density poli-ethylene) liner. During the digging operations performed to build a nearby new landfill, leachate was found, triggering an in-depth investigation including also non-invasive methods. The principal goal was to verify whether the leachate is indeed confined, and to what extent, by the HDPE liner. We performed both surface electrical resistivity tomography (ERT) and mise-à-la-masse (MALM) surveys, facing the severe challenges posed by the rugged terrain of the abandoned quarry complex. A conductive body, probably associated with leachate, was found as deep as 40 m below the current landfill surface i.e. at a depth much larger than the expected 20 m thickness of waste. Given the logistical difficulties that limit the geometry of acquisition, we utilized synthetic forward modeling in order to confirm/dismiss interpretational hypotheses emerging from the ERT and MALM results. This integration between measurements and modeling helped narrow the alternative interpretations and strengthened the confidence in results, confirming the effectiveness of non-invasive methods in landfill investigation and the importance of modeling in the interpretation of geophysical results.

  12. Towards improved 3D cross-borehole electrical resistivity imaging of discrete fracture networks

    NASA Astrophysics Data System (ADS)

    Robinson, J.; Slater, L. D.; Johnson, T. J.; Ntarlagiannis, D.; Lacombe, P.; Johnson, C. D.; Tiedeman, C. R.; Goode, D.; Day-Lewis, F. D.; Shapiro, A. M.; Lane, J. W.

    2012-12-01

    There is a need to better characterize discrete fractures in contaminated bedrock aquifers to determine the migration of injected remediation amendments away from boreholes. A synthetic cross-borehole electrical resistivity study was conducted assuming a discrete fracture model of an existing contaminated site with known fracture locations. Four boreholes and two discrete fracture zones, assumed to be the dominant electrical and hydraulically conductive pathways, were explicitly modeled within an unstructured tetrahedral finite-element mesh. To simulate field conditions, 5% random Gaussian noise was added to all synthetic datasets. We first evaluated different regularization constraints starting with an uninformed smoothness-constrained inversion, to which a priori information was incrementally added. We found major improvements when (1) smoothness regularization constraints were relaxed (or disconnected) along boreholes and fractures, (2) a homogeneous conductivity was assumed along boreholes, and (3) borehole conductivity constraints, which could be determined from a fluid specific-conductance log, were applied. We also evaluated the effect of including borehole packers on the fracture-zone model recovery. We found the estimated fracture-zone conductivities with the inclusion of packers were comparable to similar trials excluding the use of packers regardless of electrical potential changes. The misplacement of fracture regularization disconnects easily can be misinterpreted as actual fracture locations. Conductivities within misplaced disconnects were near the starting model value and removing smoothing between boreholes and assumed fracture locations helped in identifying incorrectly located fracture regularization disconnects. Model sensitivity structure improved when regularization disconnects were (1) applied along the boreholes and fracture zones, and (2) fracture-zone regularization disconnects were placed where actual fractures existed. A field study being conducted at a contaminated fractured rock site, the Naval Air Warfare Center (NAWC) in West Trenton, New Jersey, is being used to validate our approach. Electrical resistance measurements, borehole geophysical logs and hydraulic tests are being acquired from seven, 10 cm (4 in.) boreholes to characterize fractures in the contaminated fractured rock and monitor time-lapse amendment injections to determine the amendment transport path at the field scale. Our findings, to be validated in a field study, demonstrate that structural constraints used after careful evaluation of a priori information are critical to improving imaging of fracture electrical conductivities, locations and orientations.

  13. Characterization of electric vehicle velocity and power profiles using road test data

    SciTech Connect

    Burke, A.F.; Fink, R.K.; Richardson, R.A.; Dowgiallo, E.J. (EG and G Idaho, Inc., Idaho Falls, ID (USA); USDOE, Washington, DC (USA))

    1989-01-01

    The use of electric vehicle road test data to characterize various missions in terms of velocity time-histories and battery power profiles is discussed. The data utilized were taken on the Griffon Van at Detroit Edison using the VDAS on-board data system, which stores the data in several frequency-of-occurrence matrices. Time-based data are not available from VDAS. Construction of velocity-time cycles from the mechanical power-velocity matrices has proven to be difficult. A new VDAS, which stores the vehicle/battery data in time-based files, has been designed and built at the INEL. Bench testing of the unit is near completion and in-vehicle testing should begin in June 1989. The new VDAS utilizes the same sensors as in the original VDAS and will yield essentially the same data variables. The frequency-of-occurrence matrices can be constructed from the time-based data using a Vax 2000 workstation and commercially available software. Work is continuing on developing vehicle and battery test cycles from VDAS field data for the various missions. The availability of vehicle and battery data taken with an on-board data system permits the characterization of a variety of missions for different vehicle powertrains and batteries. Vehicle and battery designers will then have the information needed to assess the suitability of particular vehicle and battery designs for particular missions and applications. 6 refs., 8 figs., 4 tabs.

  14. Impact of nitrogen depth profiles on the electrical properties of crystalline high-K gate dielectrics

    NASA Astrophysics Data System (ADS)

    Huang, Jhih-Jie; Tsai, Yi-Jen; Tsai, Meng-Chen; Huang, Li-Tien; Lee, Min-Hung; Chen, Miin-Jang

    2015-01-01

    The electrical characteristics of crystalline ZrO2 gate dielectrics with different nitrogen depth profiles were investigated, which were treated by the in-situ atomic layer doping of nitrogen and post-deposition nitridation processes, respectively, using remote NH3 plasma at a low treatment temperature of 250 °C. The crystalline ZrO2 gate dielectric of the tetragonal/cubic phase was formed by post-metallization annealing (PMA) at a low temperature of 450 °C, resulting in an increase of the dielectric constant. As compared with the in-situ atomic layer doping of nitrogen, the post-deposition nitrogen process leads to a lower capacitance equivalent thickness of 1.13 nm with a low leakage current density of 1.35 × 10-5 A/cm2. The enhanced capacitance density caused by the post-deposition nitrogen treatment may be ascribed to the high nitrogen concentration at the top surface of gate dielectric, giving rise to the suppression of oxygen diffusion from the ambient toward the interface and so a thinner interfacial layer. The result reveals that the nitrogen incorporation at the top surface of gate oxide is favorable to the scaling of crystalline high-K gate dielectrics.

  15. Gas production and transport during bench-scale electrical resistance heating of water and trichloroethene

    NASA Astrophysics Data System (ADS)

    Hegele, P. R.; Mumford, K. G.

    2014-09-01

    The effective remediation of chlorinated solvent source zones using in situ thermal treatment requires successful capture of gas that is produced. Replicate electrical resistance heating experiments were performed in a thin bench-scale apparatus, where water was boiled and pooled dense non-aqueous phase liquid (DNAPL) trichloroethene (TCE) and water were co-boiled in unconsolidated silica sand. Quantitative light transmission visualization was used to assess gas production and transport mechanisms. In the water boiling experiments, nucleation, growth and coalescence of the gas phase into connected channels were observed at critical gas saturations of Sgc = 0.233 ± 0.017, which allowed for continuous gas transport out of the sand. In experiments containing a colder region above a target heated zone, condensation prevented the formation of steam channels and discrete gas clusters that mobilized into colder regions were trapped soon after discontinuous transport began. In the TCE-water experiments, co-boiling at immiscible fluid interfaces resulted in discontinuous gas transport above the DNAPL pool. Redistribution of DNAPL was also observed above the pool and at the edge of the vapor front that propagated upwards through colder regions. These results suggest that the subsurface should be heated to water boiling temperatures to facilitate gas transport from specific locations of DNAPL to extraction points and reduce the potential for DNAPL redistribution. Decreases in electric current were observed at the onset of gas phase production, which suggests that coupled electrical current and temperature measurements may provide a reliable metric to assess gas phase development.

  16. Dynamic Inversion for Hydrological Process Monitoring with Electrical Resistance Tomography Under Model Uncertainty

    SciTech Connect

    Lehikoinen, A.; Huttunen, J.M.J.; Finsterle, S.; Kowalsky, M.B.; Kaipio, J.P.

    2009-08-01

    We propose an approach for imaging the dynamics of complex hydrological processes. The evolution of electrically conductive fluids in porous media is imaged using time-lapse electrical resistance tomography. The related dynamic inversion problem is solved using Bayesian filtering techniques, that is, it is formulated as a sequential state estimation problem in which the target is an evolving posterior probability density of the system state. The dynamical inversion framework is based on the state space representation of the system, which involves the construction of a stochastic evolution model and an observation model. The observation model used in this paper consists of the complete electrode model for ERT, with Archie's law relating saturations to electrical conductivity. The evolution model is an approximate model for simulating flow through partially saturated porous media. Unavoidable modeling and approximation errors in both the observation and evolution models are considered by computing approximate statistics for these errors. These models are then included in the construction of the posterior probability density of the estimated system state. This approximation error method allows the use of approximate - and therefore computationally efficient - observation and evolution models in the Bayesian filtering. We consider a synthetic example and show that the incorporation of an explicit model for the model uncertainties in the state space representation can yield better estimates than a frame-by-frame imaging approach.

  17. Antimicrobial resistance profile of five major food-borne pathogens isolated from beef, pork and poultry.

    PubMed

    Mayrhofer, Sigrid; Paulsen, Peter; Smulders, Frans J M; Hilbert, Friederike

    2004-12-01

    This study was performed to evaluate the resistance rate against antimicrobials of food isolates of the five major food-borne pathogens to compare these and to possibly distinguish a pattern. A total of 922 samples of the major meat species (pork, beef and poultry) were analysed for thermophilic Campylobacter, Salmonella, Yersinia enterocolitica, pathogenic Escherichia coli and Listeria monocytogenes. Isolates were subjected to antimicrobial resistance testing by the disc diffusion method. Roughly the same overall rate of resistance was identified for thermophilic Campylobacter, Salmonella and pathogenic E. coli. Resistance to quinolones and tetracycline was determined most frequently. In contrast, food isolates of Y. enterocolitica and L. monocytogenes were rarely tested resistant. The significance of our findings is that resistance rates in enteric bacteria seem to be much higher than in pathogens found in a variety of environments, closely associated to the host environment. PMID:15527915

  18. Transcription and induction profiles of two esterase genes in susceptible and acaricide-resistant Tetranychus cinnabarinus

    Microsoft Academic Search

    Ya-ning Feng; Jin Yan; Wei Sun; Shu Zhao; Wen-Cai Lu; Ming Li; Lin He

    2011-01-01

    The carmine spider mite Tetranychus cinnabarinus is the most serious of crop mite pests in China. Their ability to rapidly develop resistance to acaricides has caused difficulty in controlling this mite. In this study, the molecular mechanism of acaricide resistance associated with esterase genes TCE1 and TCE2 was investigated in susceptible and acaricide-resistant strains of T. cinnabarinus. The quantitative real-time

  19. Electrical Resistivity and Seismic Surveys at the Nevada Test Site, Nevada, April 2007

    SciTech Connect

    Seth S. Haines; Bethany L. Burton; Donald S. Sweetkind; Theodore H. Asch

    2009-03-30

    In April 2007, the USGS collected direct-current (DC) electrical resistivity data and shear- (S) and compressional- (P) wave seismic data to provide new detail of previously mapped, overlapping fault splays at two administrative areas in the Nevada Test Site (NTS). In NTS Area 7, we collected two-dimensional DC resistivity data along a transect crossing the Yucca Fault parallel to, and between, two transects along which resistivity data were collected in a previous study in 2006. In addition, we collected three-dimensional DC resistivity data in a grid that overlies part of the 2007 transect. The DC resistivity data show that the fault has a footwall that is more conductive than the hanging wall and an along-strike progression of the fault in a location where overlapping splays are present. Co-located with the northernmost of the two 2006 DC resistivity transects, we acquired S- and P-wave seismic data for both reflection and refraction processing. The S-wave data are corrupted by large amounts of converted (P-wave) energy likely due to the abundance of fractured caliche in the shallow subsurface. The P-wave data show minimal reflected energy, but they show clear refracted first arrivals. We have inverted these first arrival times to determine P-wave seismic velocity models. The seismic model for the transect in Area 7 shows low velocities extending to the base of the model at the location of the Yucca Fault, as well as low velocities at the eastern end of the transect, in the vicinity of the adjacent crater. These new surveys provide further detail about the geometry of the Yucca Fault in this location where it shows two overlapping splays. We collected P- and S-wave seismic data along a transect in the southern part of NTS Area 2, corresponding with the location of a 2006 DC resistivity transect that targeted a set of small faults identified with field mapping. Again, the S-wave data are difficult to interpret. The P-wave data show clear first arrivals that we inverted, yielding a velocity model that shows lateral heterogeneity similar to the 2006 DC resistivity models. Finally, we collected P-wave data along a second transect in Area 2, located north of the first line and in an area of a very minor fault that was targeted by another 2006 DC resistivity survey. The P-wave refraction velocity model shows generally high velocities, with a zone of somewhat lower velocities in the central part of the transect. The position of the low velocity zone corresponds with the location of a minor fault, though it is unclear whether the two are related. Together, these results demonstrate the value of geophysical data for mapping the subsurface extent of faults. The 2007 DC resistivity data complement the 2006 data and provide important new detail of the overlapping fault splays. The seismic data demonstrate the ability of P-wave refraction methods to identify the damage zones at faults, and they show the difficulties associated with S-wave methods in areas with caliche. Combining all of the geophysical data from the Area 7 studies, we are able to develop a coherent interpretation of the relation between the site geology, the fault, and the observations.

  20. Multiple pulse-heating experiments with different current to determine total emissivity, heat capacity, and electrical resistivity of electrically conductive materials at high temperatures.

    PubMed

    Watanabe, Hiromichi; Yamashita, Yuichiro

    2012-01-01

    A modified pulse-heating method is proposed to improve the accuracy of measurement of the hemispherical total emissivity, specific heat capacity, and electrical resistivity of electrically conductive materials at high temperatures. The proposed method is based on the analysis of a series of rapid resistive self-heating experiments on a sample heated at different temperature rates. The method is used to measure the three properties of the IG-110 grade of isotropic graphite at temperatures from 850 to 1800 K. The problem of the extrinsic heating-rate effect, which reduces the accuracy of the measurements, is successfully mitigated by compensating for the generally neglected experimental error associated with the electrical measurands (current and voltage). The results obtained by the proposed method can be validated by the linearity of measured quantities used in the property determinations. The results are in reasonably good agreement with previously published data, which demonstrate the suitability of the proposed method, in particular, to the resistivity and total emissivity measurements. An interesting result is the existence of a minimum in the emissivity of the isotropic graphite at around 1120 K, consistent with the electrical resistivity results. PMID:22299976

  1. Simulated Fuel Economy and Performance of Advanced Hybrid Electric and Plug-in Hybrid Electric Vehicles Using In-Use Travel Profiles

    SciTech Connect

    Earleywine, M.; Gonder, J.; Markel, T.; Thornton, M.

    2010-01-01

    As vehicle powertrain efficiency increases through electrification, consumer travel and driving behavior have significantly more influence on the potential fuel consumption of these vehicles. Therefore, it is critical to have a good understanding of in-use or 'real world' driving behavior if accurate fuel consumption estimates of electric drive vehicles are to be achieved. Regional travel surveys using Global Positioning System (GPS) equipment have been found to provide an excellent source of in-use driving profiles. In this study, a variety of vehicle powertrain options were developed and their performance was simulated over GPS-derived driving profiles for 783 vehicles operating in Texas. The results include statistical comparisons of the driving profiles versus national data sets, driving performance characteristics compared with standard drive cycles, and expected petroleum displacement benefits from the electrified vehicles given various vehicle charging scenarios.

  2. Development of an electrical resistivity cone for the detection of gas hydrates in marine sediments

    E-print Network

    McClelland, Martha Ann

    1994-01-01

    in the detection of thin resistive layers and randomly dispersed resistive nodules. The laboratory test results indicated that the four-electrode configuration may be more appropriate for the detection of both thin resistive layers and random resistive nodules...

  3. Transcription profiling of a recently colonised pyrethroid resistant Anopheles gambiae strain from Ghana

    PubMed Central

    Müller, Pie; Donnelly, Martin J; Ranson, Hilary

    2007-01-01

    Background Mosquito resistance to the pyrethroid insecticides used to treat bednets threatens the sustainability of malaria control in sub-Saharan Africa. While the impact of target site insensitivity alleles is being widely discussed the implications of insecticide detoxification – though equally important – remains elusive. The successful development of new tools for malaria intervention and management requires a comprehensive understanding of insecticide resistance, including metabolic resistance mechanisms. Although three enzyme families (cytochrome P450s, glutathione S-transferases and carboxylesterases) have been widely associated with insecticide detoxification the role of individual enzymes is largely unknown. Results Here, constitutive expression patterns of genes putatively involved in conferring pyrethroid resistance was investigated in a recently colonised pyrethroid resistant Anopheles gambiae strain from Odumasy, Southern Ghana. RNA from the resistant strain and a standard laboratory susceptible strain, of both sexes was extracted, reverse transcribed and labelled with either Cy3- or Cy5-dye. Labelled cDNA was co-hybridised to the detox chip, a custom-made microarray containing over 230 A. gambiae gene fragments predominantly from enzyme families associated with insecticide resistance. After hybridisation, Cy3- and Cy5-signal intensities were measured and compared gene by gene. In both females and males of the resistant strain the cytochrome P450s CYP6Z2 and CYP6M2 are highly over-expressed along with a member of the superoxide dismutase (SOD) gene family. Conclusion These genes differ from those found up-regulated in East African strains of pyrethroid resistant A. gambiae and constitute a novel set of candidate genes implicated in insecticide detoxification. These data suggest that metabolic resistance may have multiple origins in A. gambiae, which has strong implications for the management of resistance. PMID:17261191

  4. Antimicrobial resistance profi