Three dimensional electrical potential analyser

1952 ◽  
Vol 3 (2) ◽  
pp. 58-58
Author(s):  
V E Gough
Keyword(s):  
Electrical Potential ◽  
Three Dimensional

scholarly journals Proton-Dependent Gating and Proton Uptake by Wzx Support O-Antigen-Subunit Antiport Across the Bacterial Inner Membrane

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Salim T. Islam ◽  
Paul D. W. Eckford ◽  
Michelle L. Jones ◽  
Timothy Nugent ◽  
Christine E. Bear ◽  
...  
Keyword(s):  
Cell Surface ◽  
Bacterial Cell ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Structural Data ◽  
Inner Membrane ◽  
Content Type ◽  
Bacterial Cell Surface ◽  
Repeat Units ◽  
Dependent Transport

ABSTRACTWzx flippases are crucial for bacterial cell surface polysaccharide assembly as they transport undecaprenyl pyrophosphate-linked sugar repeat units from the cytoplasmic to the periplasmic leaflets of the inner membrane (IM) for final assembly. Our recently reported three-dimensional (3D) model structure of Wzx fromPseudomonas aeruginosaPAO1 (WzxPa) displayed a cationic internal vestibule and functionally essential acidic amino acids within transmembrane segment bundles. Herein, we examined the intrinsic transport function of WzxPafollowing its purification and reconstitution in phospholipid liposomes. WzxPawas capable of mediating anion flux, consistent with its cationic interior. This flux was electrogenic and modified by extraliposomal pH. Mutation of the above-mentioned acidic residues (E61, D269, and D359) reduced proton (H+)-modified anion flux, showing the role of these amino acid side chains in H+-dependent transport. Wzx also mediated acidification of the proteoliposome interior in the presence of an outward anion gradient. These results indicate H+-dependent gating and H+uptake by WzxPaand allow for the first H+-dependent antiport mechanism to be proposed for lipid-linked oligosaccharide translocation across the bacterial IM.IMPORTANCEMany bacterial cell surface polysaccharides that are important for survival and virulence are synthesized at the periplasmic leaflet of the inner membrane (IM) using precursors produced in the cytoplasm. Wzx flippases are responsible for translocation of lipid-linked sugar repeat units across the IM and had been previously suggested to simply facilitate passive substrate diffusion. Through our characterization of purified Wzx in a reconstitution system described herein, we have observed protein-dependent intrinsic transport producing a change in the electrical potential of the system, with H+identified as the coupling ion. These results provide the first evidence for coupled (i.e., secondary active) transport by these proteins and, in conjunction with structural data, allow for an antiport mechanism to be proposed for the directed transport of lipid-linked sugar substrates across the IM. These findings bring our understanding of lipid-linked polysaccharide transporter proteins more in line with the efflux pumps to which they are evolutionarily related.

Structure of the Séchilienne unstable slope from large-scale three-dimensional electrical tomography using a Resistivity Distributed Automated System (R-DAS)

2019 ◽  
Vol 219 (1) ◽  
pp. 129-147 ◽  
Author(s):  
M Lajaunie ◽  
J Gance ◽  
P Nevers ◽  
J-P Malet ◽  
C Bertrand ◽  
...  
Keyword(s):  
Large Scale ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Automated System ◽  
Data Uncertainty ◽  
Complex Data ◽  
Electrical Tomography ◽  
Data Set ◽  
Resistivity Model ◽  
Unstable Slope

SUMMARY This work presents a 3-D resistivity model of the Séchilienne unstable slope acquired with a network of portable resistivimeters in summer 2017. The instrumentation consisted in distributed measuring systems (IRIS Instruments FullWaver) to measure the spatial variations of electrical potential. 23 V-FullWaver receivers with two 50 m dipoles have been deployed over an area of circa 2 km2; the current was injected between a fixed remote electrode and a mobile electrode grounded successively at 30 locations. The data uncertainty has been evaluated in relation to the accuracy of electrodes positioning. The software package BERT (Boundless Electrical Resistivity Tomography) is used to invert the apparent resistivity and model the complex data set providing the first 3-D resistivity model of the slope. Stability tests and synthetic tests are realized to assess the interpretability of the inverted models. The 3-D resistivity model is interpreted up to a depth of 500 m; it allows identifying resistive and conductive anomalies related to the main geological and hydrogeological structures shaping the slope. The high fracturation of the rock in the most active zone of the landslide appears as a resistive anomaly where the highest resistivity values are located close to the faults. A major drain formed by a fault in the unaltered micaschist is identified through the discharge of a perched aquifer along the conductive zone producing an important conductive anomaly contrasting with the unaltered micaschist.

The Effects of Anisotropic Transport Coefficients on Pore Pressure in Shale Formations

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Vahid Dokhani ◽  
Mengjiao Yu ◽  
Stefan Z. Miska ◽  
James Bloys
Keyword(s):  
Pore Pressure ◽  
Fluid Transport ◽  
Drilling Fluid ◽  
Transport Coefficients ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Bedding Plane ◽  
Wellbore Stability ◽  
Coupled Flow ◽  
In Situ Conditions

This study investigates shale–fluid interactions through experimental approaches under simulated in situ conditions to determine the effects of bedding plane orientation on fluid flow through shale. Current wellbore stability models are developed based on isotropic conditions, where fluid transport coefficients are only considered in the radial direction. This paper also presents a novel mathematical method, which takes into account the three-dimensional coupled flow of water and solutes due to hydraulic, chemical, and electrical potential imposed by the drilling fluid and/or the shale formation. Numerical results indicate that the presence of microfissures can change the pore pressure distribution significantly around the wellbore and thus directly affect the mechanical strength of the shale.

Three-Dimensional Identification of Semi-Elliptical Surface Crack by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor

2006 ◽  
Vol 129 (3) ◽  
pp. 441-448 ◽  
Author(s):  
Naoya Tada ◽  
Masayoshi Okada ◽  
Jun Iwamoto
Keyword(s):  
Direct Current ◽  
Surface Crack ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Crack Plane ◽  
Multiple Probe ◽  
Probe Sensor

A method of three-dimensional identification of a semi-elliptical surface crack by direct-current electrical potential difference method with a multiple-probe sensor was proposed and its validity was numerically examined. The condition of the surface crack embedded in a conductive plate was specified by the two-dimensional location of the crack center, length, and depth of the crack, and the surface and inward angles of the crack plane. Identification was carried out based on the distribution of the electrical potential difference around the crack measured on the surface of the plate with the “multiple-probe sensor” which is composed of many probes aligned in two orthogonal directions. The location and surface angle were evaluated using the point symmetry of the potential difference distribution. The inward angle was determined by the magnitude of symmetry of potential difference distribution with reference to the evaluated crack line. Finally, length and depth of the crack were determined using the exact solution of potential difference for an inclined inner elliptical crack which yields similar potential difference to that of the inclined semi-elliptical surface crack. The validity of the method was numerically confirmed by carrying out the evaluation based on the result obtained by finite element analysis.

Direct Fabrication of Highly Conductive Micro Silver Tracks Using Electrohydrodynamic Jet Printing for Sub-20 µM Micro-Manufacturing

2014 ◽  
Author(s):  
Hangtang Qin ◽  
Chuang Wei ◽  
Jingyan Dong ◽  
Yuan-Shin Lee
Keyword(s):  
Electrical Potential ◽  
Three Dimensional ◽  
Micro Manufacturing ◽  
Electrohydrodynamic Jet Printing ◽  
Biomedical Device ◽  
Direct Fabrication ◽  
Bulk Silver ◽  
Jet Printing ◽  
Alternative Current ◽  
First Time

This paper presents a direct fabrication method of highly conductive silver tracks with sub-20 μm microstructures on glass substrate by using electrohydrodynamic jet printing (EHDJP) with alternative current (AC) voltage. Traditional ink jet printing fabrication approaches are limited in the achievable resolution. EHDJP has been used in directly printing by generating a fine jet through a large electrical potential between nozzle and substrate. When charge accumulates on the ink meniscus at the nozzle, a fine jet down to nano scale can be generated. In the paper, we successfully applied EHDJP for fabrication of highly conductive silver tracks using AC voltage. It was the first time that sub-20 μm silver tracks were demonstrated and printed with resistivity about 3.16 times than bulk silver. The variables of fabrication process were investigated to achieve reliable jet printing of conductive silver tracks. The topography of printed tracks was characterized and verified in the study. The presented technique can be used for micro-manufacturing of three-dimensional microstructures and biomedical device fabrications.

Three-Dimensional Identification of Semi-Elliptical Crack on the Back Surface by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor (PVP2006-ICPVT-11-93359)

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Naoya Tada ◽  
Akira Funakoshi
Keyword(s):  
Direct Current ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Elliptical Crack ◽  
Potential Difference ◽  
Back Surface ◽  
Electrical Potential Difference ◽  
Multiple Probe ◽  
Probe Sensor

Cracks are popular defects initiated in structural components and their accurate evaluation is very important to assure the reliability of various plants. The direct-current electrical potential difference method is known as one of the most effective methods for the evaluation of the cracks. In this paper, a method of three-dimensional identification of a semi-elliptical crack existing on the back surface of a conductive plate by the direct-current electrical potential difference method with a multiple-probe sensor is proposed. The geometrical condition of the crack was specified by six parameters, the surface and inward angles of the crack plane, θsur and θin, the length and depth of the crack, c and a, and the two-dimensional location of the crack center, (yc,zc), on the back surface. The identification was carried out based on the distribution of electrical potential difference on the surface of the plate measured with a sensor composed of grid-arranged multiple probes called the “multiple-probe sensor.” As an approximate cracked body and a quick analysis method were used, a number of repeated electrical potential field analyses necessary for the identification of the crack became possible within a practical time. The validity of the method was numerically confirmed by carrying out the identification based on the result of the finite element analysis. The proposed method could be extended to the online monitoring of a semi-elliptical crack initiated on the inner surface of tubular components by means of the multiple-probe sensor placed on the outer surface.

Model studies of electrical leak detection surveys in geomembrane‐lined impoundments

Geophysics ◽  
1988 ◽  
Vol 53 (11) ◽  
pp. 1453-1458 ◽  
Author(s):  
J. O. Parra ◽  
T. E. Owen
Keyword(s):  
Field Survey ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Liquid Waste ◽  
Finite Size ◽  
Leak Detection ◽  
Electrode Spacing ◽  
Model Studies ◽  
Optimum Selection ◽  
Selection Of

Pole‐dipole array electrical potential distributions are calculated for a geomembrane‐lined liquid impoundment having single or multiple leaks. A three‐dimensional numerical model is employed to represent a small circular leak in the highly resistive plastic liner. The liquid waste material, the liner, and the soil under the impoundment are simulated by infinite horizontal layers, with approximate corrections for the finite size of the impoundment. Parametric curves for a single leak show that with optimum selection of electrode spacing and positioning and other field survey parameters, leaks can be detected effectively. To identify and resolve the presence of a cluster of leaks, the potential measurements must be made close to the liner and the detector dipole spacing must be smaller than the separation of the leaks. The results also indicate that the survey speed may be increased when portable leak detection equipment employing a vertical dipole detector is used.

Three-Dimensional Nanoscale Imaging of Polymer Bulk-Heterojunction by Scanning Electrical Potential Microscopy and C60+Cluster Ion Slicing

2009 ◽  
Vol 81 (21) ◽  
pp. 8936-8941 ◽  
Author(s):  
Bang-Ying Yu ◽  
Wei-Chun Lin ◽  
Jen-Hsien Huang ◽  
Chih-Wei Chu ◽  
Yu-Chin Lin ◽  
...  
Keyword(s):  
Bulk Heterojunction ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Polymer Bulk ◽  
Nanoscale Imaging ◽  
Cluster Ion

Three‐dimensional model results for an electrical hole‐to‐surface method: Application to the interpretation of a field survey

Geophysics ◽  
1988 ◽  
Vol 53 (1) ◽  
pp. 85-103 ◽  
Author(s):  
D. Le Masne ◽  
C. Poirmeur
Keyword(s):  
Field Survey ◽  
Current Source ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Electrical Parameters ◽  
Three Dimensional Model ◽  
Borehole Geophysics ◽  
Homogeneous Half Space ◽  
Surface Method ◽  
Three Dimensional Models

An important objective of borehole geophysics is to maximize information about inhomogeneities in the vicinity of existing boreholes. Three‐dimensional models (parallelepipedic inhomogeneities in a homogeneous half‐space) are used here to characterize the responses of an electrical hole‐to‐surface method ELECENT (ELECtrode ENTerrée) where conductive or resistive inhomogeneities (orebodies) occur in the vicinity of a borehole. Two types of surface measurements are carried out simultaneously at each station: electrical potential V (as in mise à la masse), and associated electrical field E. These two measured parameters give rise to three other parameters, two apparent resistivities (one for each V and E case) and another parameter quantifying the orientation of the E field. The influence of various geometrical and electrical parameters (such as the horizontal and vertical distances between the current source, the stations, and the inhomogeneity, and the size and resistivity of the inhomogeneity) on the five parameters above appears to be important. Values and positions of the extrema of these five parameters are characteristic of the geometrical and electrical parameters of the models. The orientation of the E field, for instance, is found to be critical to determining the shape of the inhomogeneity and its depth relative to the current source. The theoretical results obtained are used to interpret a field survey carried out around a borehole at the Beauvain prospect in France. Field maps of the five parameters show characteristics similar to the models described in the theoretical part of the study.

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