Relevant bibliographies by topics / Simultaneous measurement of potential and current

Academic literature on the topic 'Simultaneous measurement of potential and current'

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Published: 8 June 2024

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Journal articles on the topic "Simultaneous measurement of potential and current":

Majima, Yutaka, Shin-ichiro Miyamoto, Yutaka Oyama, and Mitsumasa Iwamoto. "Tunneling Current and Surface Potential Simultaneous Measurement Using a Scanning Probe." Japanese Journal of Applied Physics 37, Part 1, No. 8 (August 15, 1998): 4557–60. http://dx.doi.org/10.1143/jjap.37.4557.

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Spurgeon, H. A., M. D. Stern, G. Baartz, S. Raffaeli, R. G. Hansford, A. Talo, E. G. Lakatta, and M. C. Capogrossi. "Simultaneous measurement of Ca2+, contraction, and potential in cardiac myocytes." American Journal of Physiology-Heart and Circulatory Physiology 258, no. 2 (February 1, 1990): H574—H586. http://dx.doi.org/10.1152/ajpheart.1990.258.2.h574.

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A system is described that can simultaneously record cytosolic Ca2+ concentration ([Ca2+]i), cell length, and either membrane potential or current in single cardiac myocytes loaded with the fluorescent Ca2+ indicator indo-1. Fluorescence is excited by epi-illumination with 3.8-microsecond flashes of 350 +/- 5 nm light from a xenon arc. Indo-1 fluoresence is measured simultaneously in spectral windows of 391-434 nm and 457-507 nm, and the ratio of indo-1 emission in the two bands is computed as a measure of [Ca2+]i for each flash. With cells loaded with the permeant acetoxymethyl ester of indo-1, quantitation of [Ca2+]i is not precise, owing to subcellular compartmentation of indo-1; however, the instrument would allow full quantitation if indo-1 free acid was introduced by microinjection. Simultaneously, cell length is measured on-line from the bright-field image of the cell. Because fluorescence collection is time gated during the brief flash, and red light (650-750 nm) is used for the bright-field image, cell length and [Ca2+]i measurements are obtained simultaneously without cross talk. Membrane potential or current can be recorded simultaneously with indo-1 fluorescence and cell length via standard patch-clamping techniques.

Jourdain de Thieulloy, Marilou, Mairi Dorward, Chris Old, Roman Gabl, Thomas Davey, David M. Ingram, and Brian G. Sellar. "On the Use of a Single Beam Acoustic Current Profiler for Multi-Point Velocity Measurement in a Wave and Current Basin." Sensors 20, no. 14 (July 12, 2020): 3881. http://dx.doi.org/10.3390/s20143881.

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Harnessing the energy of tidal currents has huge potential as a source of clean renewable energy. To do so in a reliable and cost effective way, it is critical to understand the interaction between tidal turbines, waves, and turbulent currents in the ocean. Scaled testing in a tank test provides a controlled, realistic, and highly reproducible down-scaled open ocean environment, and it is a key step in gaining this understanding. Knowledge of the hydrodynamic conditions during tests is critical and measurements at multiple locations are required to accurately characterise spatially varying flow in test tank facilities. The paper presents a laboratory technique using an acoustic velocimetry instrument, the range over-which measurements are acquired being more akin to open water applications. This enables almost simultaneous multi-point measurements of uni-directional velocity along a horizontal profile. Velocity measurements have been obtained from a horizontally mounted Single Beam Acoustic Doppler (SB-ADP) profiler deployed in the FloWave Ocean Energy Research Facility at the University of Edinburgh. These measurements have been statistically compared with point measurements obtained while using a co-located Acoustic Doppler Velocimeter (ADV). Measurements were made with both instruments under flow velocities varying from 0.6 ms−1 to 1.2 ms−1, showing that flow higher than 1 ms−1 was more suitable. Using a SB-ADP has shown the advantage of gaining 54 simultaneous measurement points of uni-directional velocity, covering a significant area with a total distance of 10 m of the test-tank, at a measurement frequency of 16 Hz. Of those measurement points, 41 were compared with co-located ADV measurements covering 8 m of the profile for a tank nominal flow velocity of 0.8 ms−1, and four distributed locations were chosen to to carry out the study at 0.6 ms−1, 1.0 ms−1, and 1.2 ms−1. The comparison with the ADV measurement showed a 2% relative bias on average.

Oyama, Yutaka, Yutaka Majima, and Mitsumasa Iwamoto. "Analysis of scanning probe used for simultaneous measurement of tunneling current and surface potential." Journal of Applied Physics 86, no. 12 (December 15, 1999): 7087–93. http://dx.doi.org/10.1063/1.371796.

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HUDDAR, B. B., and K. R. RAO. "A combined sonde for the measurement of electrical conductivity and potential gradient in the atmosphere." MAUSAM 23, no. 2 (February 3, 2022): 185–88. http://dx.doi.org/10.54302/mausam.v23i2.5276.

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The paper describes a combined sonde for the simultaneous measurement of the vertical distribution of electrical conductivity and potential gradient in the upper atmosphere during a balloon flight. The data obtained helps in evaluating the third parameter, i.e., air earth conduction current at all levels. Thus all the three main parameters of the atmosphericelectrioity can be measured with a single sonde. A typical sounding taken with the above instrument is also presented.

Mulberry, Geoffrey, Kevin A. White, Matthew A. Crocker, and Brian N. Kim. "A 512-Ch Dual-Mode Microchip for Simultaneous Measurements of Electrophysiological and Neurochemical Activities." Biosensors 13, no. 5 (April 26, 2023): 502. http://dx.doi.org/10.3390/bios13050502.

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In the study of the brain, large and high-density microelectrode arrays have been widely used to study the behavior of neurotransmission. CMOS technology has facilitated these devices by enabling the integration of high-performance amplifiers directly on-chip. Usually, these large arrays measure only the voltage spikes resulting from action potentials traveling along firing neuronal cells. However, at synapses, communication between neurons occurs by the release of neurotransmitters, which cannot be measured on typical CMOS electrophysiology devices. Development of electrochemical amplifiers has resulted in the measurement of neurotransmitter exocytosis down to the level of a single vesicle. To effectively monitor the complete picture of neurotransmission, measurement of both action potentials and neurotransmitter activity is needed. Current efforts have not resulted in a device that is capable of the simultaneous measurement of action potential and neurotransmitter release at the same spatiotemporal resolution needed for a comprehensive study of neurotransmission. In this paper, we present a true dual-mode CMOS device that fully integrates 256-ch electrophysiology amplifiers and 256-ch electrochemical amplifiers, along with an on-chip 512 electrode microelectrode array capable of simultaneous measurement from all 512 channels.

Yokota, Kazumichi, Muneaki Hashimoto, Kazuaki Kajimoto, Masato Tanaka, Sanae Murayama, Makusu Tsutsui, Yoshihiro Nakajima, Masateru Taniguchi, and Masatoshi Kataoka. "Effect of Electrolyte Concentration on Cell Sensing by Measuring Ionic Current Waveform through Micropores." Biosensors 11, no. 3 (March 12, 2021): 78. http://dx.doi.org/10.3390/bios11030078.

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Immunostaining has been widely used in cancer prognosis for the quantitative detection of cancer cells present in the bloodstream. However, conventional detection methods based on the target membrane protein expression exhibit the risk of missing cancer cells owing to variable protein expressions. In this study, the resistive pulse method (RPM) was employed to discriminate between cultured cancer cells (NCI-H1650) and T lymphoblastoid leukemia cells (CCRF-CEM) by measuring the ionic current response of cells flowing through a micro-space. The height and shape of a pulse signal were used for the simultaneous measurement of size, deformability, and surface charge of individual cells. An accurate discrimination of cancer cells could not be obtained using 1.0 × phosphate-buffered saline (PBS) as an electrolyte solution to compare the size measurements by a microscopic observation. However, an accurate discrimination of cancer cells with a discrimination error rate of 4.5 ± 0.5% was achieved using 0.5 × PBS containing 2.77% glucose as the electrolyte solution. The potential application of RPM for the accurate discrimination of cancer cells from leukocytes was demonstrated through the measurement of the individual cell size, deformability, and surface charge in a solution with a low electrolyte concentration.

Ajito, Saya, Eiji Tada, Azusa Ooi, and Atsushi Nishikata. "Simultaneous Measurements of Corrosion Potential and Hydrogen Permeation Current in Atmospheric Corrosion of Steel." ISIJ International 59, no. 9 (September 15, 2019): 1659–66. http://dx.doi.org/10.2355/isijinternational.isijint-2019-113.

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Ozaki, H., R. J. Stevens, D. P. Blondfield, N. G. Publicover, and K. M. Sanders. "Simultaneous measurement of membrane potential, cytosolic Ca2+, and tension in intact smooth muscles." American Journal of Physiology-Cell Physiology 260, no. 5 (May 1, 1991): C917—C925. http://dx.doi.org/10.1152/ajpcell.1991.260.5.c917.

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Microelectrode techniques and the fluorescent Ca2+ indicator indo-1 were used to measure membrane potential, cytosolic Ca2+ ([Ca2+]cyt), and muscle tension simultaneously in canine antral smooth muscles. Responses of muscles from the myenteric and submucosal regions were compared, since electrical activity and excitation-contraction coupling in these regions differ. The upstroke phase of electrical slow waves in both regions induced an increase in [Ca2+]cyt. In myenteric muscles the plateau phase of slow waves often caused either a further rise in [Ca2+]cyt or maintenance of the level reached during the upstroke event. In submucosal muscles, the plateau phase was significantly smaller and did not induce a second phase in the Ca2+ transient. Contractions were related to the amplitudes of Ca2+ transients. Acetylcholine (ACh; 3 x 10(-8)-10(-6) M) increased the amplitude and duration of the plateau phase of slow waves in a concentration-dependent manner. ACh also increased the second phase of Ca2+ transients and contractile responses associated with the plateau potential. In submucosal muscles ACh induced a significant increase in the plateau phase of the slow wave and increased the corresponding phase of Ca2+ transient. Nicardipine (10(-6) M) inhibited plateau phase of slow waves and the associated increases in [Ca2+]cyt and muscle tension. BAY K 8644 (10(-7) M) augmented the plateau potential and increased [Ca2+]cyt and muscle tension. These results suggest that dihydropyridine-sensitive Ca2+ currents participate in the plateau potential. Cholinergic stimulation modulates [Ca2+]cyt and therefore force by regulating the amount of Ca2+ entering cells through these channels.

Smirnova, N. F., and G. Stanev. "Estimation of the Electron Density in the Near 3–4 RE Magnetosphere Based on the Measurement of the Interball-2 Satellite Potential." Космические исследования 61, no. 3 (May 1, 2023): 202–14. http://dx.doi.org/10.31857/s0023420622700066.

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A new method is proposed for determining the electron density in rarefied plasma, based on simultaneous measurements of the Interball-2 satellite potential using IESP-2 (electric field instrument) and KM-7 (electron temperature sensor) probe devices. This makes it possible to estimate the photoelectron current density based on a procedure proposed earlier by the authors of this study. The electron concentration was determined only for the positive potential of the spacecraft. The balance equations for the satellite and the probe between the currents of the surrounding plasma electrons and photoelectrons emitted by the illuminated surface were compiled. In the magnetosphere, to bring the probe potential to the potential of the surrounding plasma, a bias current is directed into the probe, which was taken into account in the current balance equation for the probe. The electron energy used in the calculations was kTe = 1 eV. We analyzed data from ~350 orbits in the auroral region of the magnetosphere at altitudes of 2–3 RE from October 1996 to March 1998 during the period of low solar activity at the beginning of the 23rd cycle. Examples of the calculated electron density are given, which is in the range of 1–30 cm–3.

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Dissertations / Theses on the topic "Simultaneous measurement of potential and current":

Kaliszczak, Magdalena. "Polarisation chimique de l'interface liquide-liquide vers une cocristallisation contrôlée." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0332.

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La formation contrôlée de cocristaux est un objectif important dans le developpement de médicaments. Ce travail a utilisé l'électrochimie à l'interface entre deux liquides non miscibles (ITIES) pour contrôler la formation de cocristaux. Dans la première partie, le comportement électrochimique de la caféine a été étudié au moyen de la voltampérométrie cyclique (CV) et de la voltampérométrie à courant alternatif (ACV). La caféine est un cation hydrophile donc, elle a été transférée à un potentiel hautement positif. Le transfert de la caféine (CaffH+) a été vérifié à différents pH et le pH 2 a été choisi comme étant le plus optimal pour la formation de cocristaux. L'expérience de contrôle a prouvé que le 1-hydroxy-2-naphtoïque (1H2N) ne transfére pas à l'ITIES. L'ACV a fourni des informations sur l'influence de la composition de la phase aqueuse et organique. Les valeurs ont changé lorsque CaffH+ seul, 1H2N seul et 1H2N et CaffH+ étaient présents dans la phase aqueuse. Ces résultats suggèrent que ces deux molécules sont actives au niveau interfacial. Dans la deuxième partie, la cocristallisation de Caff et 1H2N a été étudiée à l'ITIES sous polarisation chimique. L'interface a été polarisée par l'ajout d'anions hydrophobes à la phase organique. De cette façon, une cocristallisation sélective a été obtenue, comme vérifié par la diffraction des rayons X et la spectroscopie Raman. Des potentiels interfaciaux positifs ont favorisé la formation d'une forme polymorphe de cocristal de Caff : 1H2N et un potentiel négatif a inhibé la cocristallisation à l'interface liquide-liquide. Cette approche du contrôle électrochimique de la cocristallisation ouvre de nouvelles possibilités pour le développement de médicaments. Dans la troisième partie, la mesure simultanée des variations de potentiel (∆E) et de courant (I) aux ITIES, qui ont été polarisées en utilisant des cations tétraalkylammonium comme ion commun a été rapportée. Divers rapports de concentration de tétraméthyl-, tétraéthyl- et tétrapropylammonium ont été dissous dans les deux phases. Ces systèmes biphasiques ont ensuite été utilisés pour vérifier que la différence de potentiel interfacial mesurée correspondait aux calculs théoriques. Ce dispositif expérimental a ensuite été utilisé pour étudier le processus de cocristallisation interfaciale de CaffH+ hydrophile et cationique avec 1H2N lipophile. La présence de caféine dans la phase aqueuse a conduit à des valeurs de courant plus élevées, causées par le transfert de charge interfacial. De telles variations de courant ont été observées aussi bien en l'absence qu'en présence de 1H2N dans la phase organique. L'analyse du bruit du courant électrochimique a montré une nette différence entre les cellules dans lesquelles les cocristaux sont formés et celles dans lesquelles la cocristallisation est entravée, soit par un potentiel négatif, soit par un changement de pH. La méthode ECN est un outil puissant pour suivre les changements qui se produisent aux ITIES dans les expériences sur les ions communs par la mesure simultanée du potentiel et du courant. Dans la dernière partie, des cocristaux ont été formés sur les ITIES selon les conditions choisies par la méthode des plans d'expériences (DoE). Différents facteurs ont été testés : électrolytes en phase aqueuse, divers solvants et sels appliquant un potentiel positif. L'analyse XRD a montré les conditions permettant d'obtenir une phase I et une phase II presque pures. L'étude des ∆E et I simultanés et de la tension interfaciale a prouvé que le potentiel appliqué influence la cinétique du processus de cocristallisation. La méthode DoE a indiqué que le sel organique est le facteur ayant un impact actif sur la cocristallisation aux ITIES
Controlled formation of cocrystals is an important objective in drug development. This work used the electrochemistry at interface between two immiscible liquids (ITIES) to control the formation of cocrystals. In the first part, the electrochemical behaviour of caffeine was investigated by the means of cyclic voltammetry (CV) and alternating current voltammetry (ACV). The caffeine is the hydrophilic cation thus, it transferred at highly positive potential. Transfer of caffeine (Caff) was verified at various pH and the pH 2 was chosen to be the most optimal for the cocrystals formation. The control experiment proved that 1-hydroxy-2-naphthoic (1H2N) did not transfer at ITIES. ACV provided the information about the influence of the aqueous and organic phase composition. Values have changed when CaffH+ alone, 1H2N alone and both 1H2N and CaffH+ were present in the aqueous phase. These suggest that these two molecules are interfacially active. In the third part the simultaneous measurement of potential (∆E) and current (I) variations at the ITIES, which were polarised using tetraalkylammonium cations as a common ion was reported. Various concentration ratios of tetramethyl-, tetraethyl-, and tetrapropylammonium were dissolved in both phases. Such biphasic systems were then used to verify that the interfacial potential difference measured fit the theoretical calculations. This experimental set-up was next used to probe the interfacial cocrystallisation process of hydrophilic and cationic CaffH+ with lipophilic 1H2N. The presence of caffeine in the aqueous phase led to higher current values, caused by interfacial charge transfer. Analysis of the electrochemical current noise showed a clear difference between cells in which cocrystals are formed and those in which cocrystallisation is hindered, either by a negative potential or by a change in pH. The EN method is a powerful tool to follow the changes occurring at ITIES in common ion experiments by simultaneous measurement of potential and current. In the last part, cocrystals were formed on the ITIES according to the conditions chosen by the design of experiments (DoE) method. Various factors were tested: electrolytes in the aqueous phase, various solvents and salts applying positive potential. The XRD analysis showed the conditions to obtain almost pure Phase I and almost pure phase II. Study of simultaneous ∆E and I and the interfacial tension proved that the applied potential influences the kinetics of the cocrystallization process. DoE method indicated organic salt as the factor having an active impact on cocrystallization at ITIES

Sellars, Malcolm. "Electric field mill for the simultaneous measurement of electric field strength and ion current diensity." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/22039.

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In the last 20 years, the use of high voltage direct current (HVDC) power transmission has grown considerably. With the increase in the number of HVDC transmission lines and in the transmission voltages, concern has increased as to possible health effects. For research on these health effects to be carried out, it is necessary to measure the electrical environment ofHVDC transmission lines accurately. The electrical environment ofHVDC transmission lines is characterised by: Electric field strength E [Vim];Ion current density J [A/m²] ;Space charge density p [C/m³ ]. Typical values measured under HVDC transmission lines are: E = lOkV/m, J = 400nA/m² . This thesis describes the design, construction and testing of an electric field mill capable of measuring electric field strength from 0 to 25kV/m (resolution = lOV/m), and ion current density from 0 to 1000 nA/m² (resolution = 20nA/m² ). The electric field readings have an accuracy of ±8%. The ion current density readings have an accuracy of ±12%. The field mill was tested in the laboratory in a simulated HVDC environment, and found to give good performance. For operation under a HVDC line, the field mill design will need some alterations to make it weatherproof. The design considerations described in this thesis should be helpful in the design of electric field mills in general.

Steedman, David John. "Simultaneous measurement of human brain activity using near infra-red spectroscopy, electroencephalogram and the steady state visually evoked potential." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/48535.

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Thesis (M.Sc.) - Swinburne University of Technology, Brain Sciences Institute, 2008.
A thesis submitted for M.Sc by Research, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 117-153)

Dragana, Naumović Vuković. "Prilog savremenom etaloniranju strujnih mernih transformatora." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2018. https://www.cris.uns.ac.rs/record.jsf?recordId=107383&source=NDLTD&language=en.

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U ovoj doktorskoj disertaciji prikazana je koncepcija, realizacija i potvrda nove metodejednovremenog etaloniranja strujnih mernih transformatora sa dve različite merneaparature. Pregledom stručne literature ne postoji podatak da je ova metoda ranijeprimenjivana. U disertaciji su prikazane različite merne metode za ispitivanje ietaloniranje mernih transformatora koje imaju primenu u savremenoj praksi i kojepodrazumevaju i različite merne mogućnosti. Takođe je i ekperimentalno potvrđenojednovremeno ispitivanje i etaloniranje strujnih mernih transformatora sa nekolikomernih aparatura koje su zasnovane na različitim metodama. Sprovedna istraživanja ieksperimentalni rezultati pokazuju i potvrđuju niz prednosti ovakvog načinaetaloniranja. Detaljna analiza komponenti merne nesigurnosti pokazala je da seprimenom ove metode postiže poboljšanje merne nesigurnost etaloniranja za skoro redveličine u odnosu na klasično pojedinačno etaloniranje sa dve različite merneaparature. Analiza uticajnih veličina na mernu nesigurnost pokazuje da se po ovoj novojmetodi etaloniranja eliminiše niz komponenti od kojih su najznačajnije: uticajnejednakosti referentnih struja i ispitnog opterećenja. Istraživanja su takođe pokazalada jednovremena metoda osim što doprinosi podizanju tačnosti etaloniranja strujnihtransformatora, ima primenu i u etaloniranju mernih aparatura za ispitivanje tačnostimernih transformatora i interkonparaciji strujnih etalon transformatora. Krozkonkretne primere realizovane u praksi, razmotreni su i prikazani načini etaloniranjamernih aparatura za ispitivanje tačnosti ovom novom metodom. Interkomparacijom dvamerna sistema visoke klase tačnosti Nacionalnog merološkog instituta Kanade(National Research Council Canada), od kojih je jedna razvijena u ElektrotehničkomInstitutu "Nikola Tesla", pokazana je i prednost primene jednovremene metode u oblastiprimarne metrologije strujnih mernih transformatora.
The dissertation presents the concept, its realisation and verification of the new methodof simultaneous comparison of the current transformers by two different measuringapparatus. It is shown by searching the literature, that this method has not been usedbefore. In this dissertation different measuring methods for testing and calibration ofcurrent transformers, with their different measuring capabilities are presented. Most ofthem have been used in recent practice. Furthermore, the experimental verification ofnew simultaneous calibration method is presented. For this reason some measuringapparatus based on different measuring methods were used. Conducted research andexperimental results confirmed a number of advantages of this calibration method.Detailed analysis of the components of the uncertainty of measurements shown thatusing simultaneous method uncertainty of measurements have been improvedcomparing to method with two individual calibration by different apparatus. In that casesome of the measuring uncertainty components can be neglected. The most significantis component caused by variation of referent current and component caused by variationof burden. The research has also showed that simultaneous method can be used forcalibration of measuring apparatus for current transformer accuracy testing and theirinter-comparisons. The ways of calibration of apparatus for current transformer accuracytesting are considered and presented, through concrete examples realized in practice.A high-accuracy comparison of two NRC (National Research Council Canada)calibration systems were carried out by new simultaneous method. One measuringsystem is developed at Electrical Engineering institute Nicola Tesla, Belgrade.Accordingly the advantage of simultaneous method applied at the primary metrology ofcurrent transformer is verified.

Benjelloun, Nadia. "Caracterisation des niveaux profonds dans le materiau photorefractif bi : :(12) geo::(20) par analyse de transitoires de courant photo-induit." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13183.

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La methode est utilisee pour l'etude de la densite d'etats dans la bande interdite du silicium amorphe hydrogene et sur cdin::(2)s::(4). La caracterisation des niveaux ayant des energies d'ionisation thermique entre 0,1 ev et 0,9 ev, le modele de transfert de charge decrivant l'effet photorefractif et l'evaluation du niveau de recombinaison, sont faits dans le materiau photorefractif. Les effets du dopage (fer) et du codopage (fer, vanadium) sur les niveaux sont consideres. Le centre responsable de la capture d'electrons est aussi etudie par absorption optique et photoconductivite photoinduites. Les resultats s'accordent avec ceux des mesures de photorefractivite

Martinez, Amy Frees. "Metaboloptics: In Vivo Optical Imaging to Enable Simultaneous Measurement of Glucose Uptake, Mitochondrial Membrane Potential, and Vascular Features in Cancer." Diss., 2016. http://hdl.handle.net/10161/13432.

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Altered metabolism is a hallmark of almost all cancers. A tumor’s metabolic phenotype can drastically change its ability to proliferate and to survive stressors such as hypoxia or therapy. Metabolism can be used as a diagnostic marker, by differentiating neoplastic and normal tissue, and as a prognostic marker, by providing information about tumor metastatic potential. Metabolism can further be used to guide treatment selection and monitoring, as cancer treatments can influence metabolism directly by targeting a specific metabolic dysfunction or indirectly by altering upstream signaling pathways. Repeated measurement of metabolic changes during the course of treatment can therefore indicate a tumor’s response or resistance. Recently, well-supported theories indicate that the ability to modulate metabolic phenotype underpins some cancer cells’ ability to remain dormant for decades and recur with an aggressive phenotype. It follows that accurate identification and repeated monitoring of a tumor’s metabolic phenotype can bolster understanding and prediction of a tumor’s behavior from diagnosis, through treatment, and (sadly) sometimes back again.

The two primary axes of metabolism are glycolysis and mitochondrial metabolism (OXPHOS), and alteration of either can promote unwanted outcomes in cancer. In particular, increased glucose uptake independent of oxygenation is a well-known mark of aggressive cancers that are more likely to metastasize and evade certain therapies. Lately, mitochondria are also gaining recognition as key contributors in tumor metabolism, and mitochondrial metabolism has been shown to promote metastasis in a variety of cell types. Most tumor types rely on a combination of both aerobic glycolysis and mitochondrial metabolism, but the two axes’ relative contributions to ATP production can vary wildly. Knowledge of both glycolytic and mitochondrial endpoints is required for actionable, systems-level understanding of tumor metabolic preference.

Several technologies exist that can measure endpoints informing on glycolytic and/or mitochondrial metabolism. However, these technologies suffer from a combination of prohibitive cost, low resolution, and lack of repeatability due to destructive sample treatments.

There is a critical need to bridge the gap in pre-clinical studies between single-endpoint whole body imaging and destructive ex vivo assays that provide multiple metabolic properties, neither of which can provide adequate spatiotemporal information for repeated tumor monitoring. Optical technologies are well-suited to non-destructive, high resolution imaging of tumor metabolism. A carefully chosen set of endpoints can be measured across a variety of length scales and resolutions to obtain a complete picture of a tumor’s metabolic state. First, the fluorescent glucose analog 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG) can be used to report on glucose uptake. The fluorophore tetramethylrhodamine, ethyl ester (TMRE) reports on mitochondrial membrane potential, which provides information regarding capacity for oxidative phosphorylation. Vascular oxygenation (SO2) and morphological features, which are critical for interpretation of 2-NBDG and TMRE uptake, can be obtained using only endogenous contrast from hemoglobin.

Three specific aims were proposed toward the ultimate goal of developing an optical imaging toolbox that utilizes exogenous fluorescence and endogenous absorption contrast to characterize cancer metabolic phenotype in vivo.

In Aim 1, we optimized the fluorescent glucose analog 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG) to report on glycolytic demand in vivo. Our primary goal was to demonstrate that correcting 2-NBDG uptake (NBDG60) by the rate of delivery (RD) showed improved contrast between distinct tumor phenotypes. We showed that the ratio 2-NBDG60/RD served as a delivery-corrected measure of glucose uptake in the dorsal skin flap window chamber models containing normal tissues and tumors. Delivery correction was able to minimize the effects of a large change in the injected 2-NBDG dose. Further, the endpoint showed a significant inverse correlation with blood glucose levels. Since glucose has been shown to competitively inhibit 2-NBDG transport into cells, this finding indicating that we were indeed reporting on glucose uptake. Importantly, the ratio was able to distinguish specific uptake of 2-NBDG from accumulation of a fluorescent control, 2-NBDLG, which is identical to 2-NBDG in molecular weight and fluorescent spectrum, but is unable to undergo active transport into the cell.

The ratio 2-NBDG60/RD was then leveraged to compare different tumor phenotypes and to characterize the dependence of glucose uptake on vascular oxygenation within these tumors. Our results showed that 2-NBDG60/RD was an effective endpoint for comparing in vivo glucose uptake of metastatic 4T1 and nonmetastatic 4T07 murine mammary adenocarcinomas. Further, the addition of vascular information revealed metabolic heterogeneity within the tumors. The primary conclusion of Aim 1 was that delivery-corrected 2-NBDG uptake (2-NBDG60/RD) is an appropriate indicator of glucose demand in both normal and tumor tissues.

In Aim 2, we optimized fluorescent tetramethyl rhodamine, ethyl ester (TMRE) for measurement of mitochondrial membrane potential (MMP). We then leveraged the relationships between MMP, glucose uptake, and vascular endpoints to characterize the in vivo metabolic landscapes of three distinct and extensively studied murine breast cancer lines: metastatic 4T1 and non-metastatic 67NR and 4T07.

Using two-photon microscopy, we confirmed that TMRE localizes to mitochondrial-sized features in the window chamber when delivered via tail vein. The kinetics of TMRE uptake were robust across both normal and tumor tissues, with a stable temporal window for measurement from 40-75 minutes after injection. We saw that TMRE uptake decreased as expected in response to hypoxia in non-tumor tissue, and in response to chemical inhibition with a mitochondrial uncoupler in both non-tumor and 4T1 tissue. MMP was increased in all tumor types relative to non-tumor (p<0.05), giving further confirmation that TMRE was reporting on mitochondrial activity.

We leveraged the relationships between the now-optimized endpoints of MMP (Aim 2), glucose uptake (Aim 1) and vascular endpoints (Aims 1 and 2) to characterize the in vivo metabolic landscapes of three distinct and extensively studied murine breast cancer lines: metastatic 4T1 and non-metastatic 67NR and 4T07. Imaging the combination of endpoints revealed a classic “Warburg effect” coupled with hyperpolarized mitochondria in 4T1; 4T1 maintained vastly increased glucose uptake and comparable MMP relative to 4T07 or 67NR across all SO2. We also showed that imaging trends were concordant with independent metabolomics analysis, though the lack of spatial and vascular data from metabolomics obscured a more detailed comparison of the technologies.

We observed that vascular features in tumor peritumoral areas (PA) were equally or more aberrant than vessels in the tumor regions that they neighbored. This prompted consideration of the metabolic phenotype of the PA. Regional metabolic cooperation between the tumor region and the PA was seen only in 4T1, where MMP was greater in 4T1 tumors and glucose uptake was greater in 4T1 PAs.

Because of their regional metabolic coupling as well as their demonstrated capacity for glycolysis and mitochondrial activity, we hypothesized that the 4T1 tumors would have an increased ability to maintain robust MMP during hypoxia. 67NR and 4T07 tumors showed expected shifts toward decreased MMP and increased glucose uptake during hypoxia, similar to the trends we observed in normal tissue. Surprisingly, 4T1 tumors appeared to increase mitochondrial metabolism during hypoxia, since MMP increased and SO2 dramatically decreased. Overall, this aim demonstrated two key findings: 1. TMRE is a suitable marker of mitochondrial membrane potential in vivo in normal tissue and tumors, and 2. imaging of multiple metabolic and vascular endpoints is crucial for the appropriate interpretation of a metabolic behavior.

Finally, in Aim 3 we evaluated the feasibility of combined 2-NBDG and TMRE imaging. The primary objective was to enable simultaneous imaging of the two fluorophores by minimizing sources of “cross-talk”: chemical reaction, optical overlap, and confounding biological effects. A secondary objective was to transition our imaging method to a new platform, a reflectance-mode, high-resolution fluorescence imaging system built in our lab, which would expand the use of our technique beyond the dorsal window chamber model. We first used liquid chromatography- mass spectrometry to confirm that the chemical properties of the two fluorophores were compatible for simultaneous use, and indeed saw that the mixing of equimolar 2-NBDG and TMRE did not form any new chemical species.

We also performed a phantom study on the hyperspectral imaging system, used for all animal imaging in Aim 1 and Aim 2, to estimate the range of 2-NBDG and TMRE concentrations that are seen at the tissue level in normal and tumor window chambers. We created a new phantom set that spanned the range of estimated in vivo concentrations, and imaged them with the reflectance-mode fluorescence imaging system. The phantom experiments gave us two important findings. First, we saw that fluorescence intensity increased linearly with fluorophore concentration, allowing for accurate quantification of concentration changes between samples. Most importantly, we found that we could exploit the optical properties of the fluorophores and our system’s spectral detection capability to excite the two fluorophores independently. Specifically, we could excite 2-NBDG with a 488nm laser without detectable emission from TMRE, and could excite TMRE with a 555nm laser without detectable emission from 2-NBDG. With this characterization, the optical properties of the two fluorophores were considered compatible for simultaneous imaging.

Next, we sought to determine whether biological or delivery interactions would affect uptake of the two fluorophores. Surprisingly, both in vitro and in vivo imaging suggested that simultaneous dosing of the 2-NBDG and TMRE caused significant changes in uptake of both probes. Since we previously found that TMRE equilibrates rapidly at the tissue site, we hypothesized that staggering the injections to allow delivery of TMRE to tissue before injecting 2-NBDG would restore the full uptake of both fluorophores. Two sequential injection protocols were used: in the first group, TMRE was injected first followed by injection of 2-NBDG after only 1-5 minutes, and in the second group, TMRE was injected first followed by injection of 2-NBDG after 10-15 minutes. Both sequential injection strategies were sufficient to restore the final fluorescence of both fluorophores to that seen in the separate TMRE or 2-NBDG imaging cohorts; however, the shorter time delay caused changes to the initial delivery kinetics of 2-NBDG. We concluded that sequential imaging of TMRE followed by 2-NBDG with a 10-15 minute delay was therefore the optimal imaging strategy to enable simultaneous quantification of glucose uptake and mitochondrial membrane potential in vivo.

Applying the sequential imaging protocol to 4T1 tumors demonstrated a highly glycolytic phenotype compared to the normal animals, as we had seen in Aim 2. However, mitochondrial membrane potential was comparable for the normal and tumor groups. The next study will test an extended delay between the injections to allow more time for TMRE delivery to tumors prior to 2-NBDG injection. Overall, the key finding of Aim 3 was that a carefully chosen delivery strategy for 2-NBDG and TMRE enabled simultaneous imaging of the two endpoints, since chemical and optical cross-talk were negligible.

The work presented here indicates that an optical toolbox of 2-NBDG, TMRE, and vascular endpoints is well poised to reveal interesting and distinct metabolic phenomena in normal tissue and tumors. Future work will focus on the integration of optical spectroscopy with the microscopy toolbox presented here, to enable long-term studies of the unknown metabolic changes underlying a tumor’s response to therapy, its escape into dormancy, and ultimately, its recurrence.

Dissertation

Books on the topic "Simultaneous measurement of potential and current":

Off-potential measurement systems for impressed current cathodic protection. [Champaign, IL]: US Army Construction Engineering Research Laboratories, 1994.

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Wang, Qingyuan. Particle-in-cell simulation of a radioactive potential probe in wind. 1991.

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Shen, Winny, and Lindsay Dhanani. Measuring and Defining Discrimination. Edited by Adrienne J. Colella and Eden B. King. Oxford University Press, 2015. http://dx.doi.org/10.1093/oxfordhb/9780199363643.013.22.

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Given the prevalence and myriad consequences associated with actual and perceived workplace discrimination, research addressing this topic has grown rapidly in recent years. This expansion of the literature has been accompanied by a proliferation of constructs, definitions, and measures. This chapter reviews and summarizes current definitions and measurement approaches, highlighting discrepancies and deficiencies where they exist in the literature. The chapter concludes by identifying gaps in the workplace discrimination literature, organized around issues of who, what, where, when, and why. Recommendations for future research include employing study designs that minimize the potential for common method variance, assessing perpetrator and target perspectives simultaneously, paying more attention to issues of timing in order to study discrimination as a dynamic and event-based phenomenon, identifying contextual factors that influence the likelihood of perceiving and reporting discrimination, and further clarifying and addressing the bases by which discrimination occurs.

Murano, Dana M., and Richard D. Roberts. Traversing the Gap Between College and Workforce Readiness: Anything But a “Bridge Too Far”! Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199373222.003.0014.

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This chapter reviews Chapters 11–13. Each chapter offers possible solutions for bridging the apparent gap between college and workforce readiness while inherently highlighting ways in which these two readiness domains are analogous. Across the chapters, an integrative framework for studying noncognitive skills across putative domains remains elusive, although it is possible. The authors also discuss various approaches to the measurement of noncognitive skills and both practical and policy implications. This chapter focuses on next steps that can be taken in an effort to resolve issues surrounding measurement and the organizational framework. It also advocates for social–emotional learning programs at the primary, secondary, and tertiary education levels to foster these skills. Juxtaposed, these chapters elucidate the current state of college and workforce readiness, potential pathways through which measurement of necessary skills can be improved, and a compelling means by which to bridge the gap between college and workforce readiness.

Williams, Paula G., Ruben Tinajero, and Yana Suchy. Executive Functioning and Health. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199935291.013.75.

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This review provides an overview of research on associations between the multi-component, cognitive construct executive functioning (EF) and health. Executive functioning is defined, and issues related to measurement are detailed. The categories of potential mechanisms by which EF may be associated with health and disease are described. Key research examining EF and health behaviors, stress processes, and chronic illness is reviewed with a focus on function (behavioral performance), as well as neuroanatomical research where relevant. Across these domains, there is evidence that EF is associated with health and illness in reciprocal, feed-forward fashion across the life span. Critical limitations of the current literature are noted, along with important future directions.

Gautié, Jérôme, and Sophie Ponthieux. Employment and the Working Poor. Edited by David Brady and Linda M. Burton. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199914050.013.22.

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This article examines the phenomenon of working poverty and issues relating to employment and the working poor. It first provides an overview of the problems of definition and measurement regarding the working poor, along with the consequences of the diversity of definitions. In particular, it considers different current definitions of the statistical category “working poor” and how definitions affect the assessment of the in-work poverty phenomenon. It also provides a “statistical” portrait of the working poor and explores how the risk of working poverty has evolved in the 2000s. Finally, it discusses the causes of working poverty, including low income at the individual level and the role of welfare states, and outlines potential remedies in terms of public policies.

Groff, Elizabeth R. Do We Really Need Collective Social Process to Understand Why Crime Occurs and Offenders Commit Crime? Edited by Gerben J. N. Bruinsma and Shane D. Johnson. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780190279707.013.4.

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This chapter examines the potential role of social process in contributing to our understanding of why crime occurs where it does. It focuses on the role of social process in explaining crime that occurs at microplaces; in “small-scale social systems whose components include people and inanimate objects” known as behavior settings. Behavior settings emphasize the situational and dynamic nature of interactions between the social and physical environment of the microplace as situated within a particular context. The chapter begins with a brief introduction to social process and its operation at microplaces. It then identifies instances where the inclusion of social process enhances current environmental criminology. It concludes by discussing some of the challenges to the measurement of social process-related mechanisms hypothesized to affect crime events and suggesting a way forward.

Pye, Stephen D., and Bajram Zeqiri. Ultrasound. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199655212.003.0025.

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Ultrasound is used in many areas of medicine, including diagnostic imaging, therapy, lithotripsy, and surgery. The chapter gives a general description of ultrasound, its propagation, bioeffects, and measurement techniques. Potential biohazards of ultrasound are tissue heating, cavitation, acoustic radiation forces, and mechanical strain due to particle displacement. Any bioeffects produced by ultrasound in diagnostic applications have little consequence for the individual, as illustrated by its routine use in diagnostic foetal scanning, but surgical techniques destroy tissue on a macroscopic scale. There are separate sections which consider exposure, standards and give practical guidance measures for each of the four main areas of medical application. All applications of ultrasound in medicine have an impressive safety record, and the 3 W cm-2 limit for therapeutic ultrasound is the only safety criterion that has been formally adopted into current international standards.

Cascio, Wayne F., and John W. Boudreau. Evidence-Based Management at the Bottom of the Pyramid. Edited by Michael A. Hitt, Susan E. Jackson, Salvador Carmona, Leonard Bierman, Christina E. Shalley, and Douglas Michael Wright. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780190650230.013.12.

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In recent years there have been growing efforts, domestically as well as internationally, to develop human resources (HR) standards that might provide useful guidance for organizations. We identify four broad types of standards: practice standards, measurement standards, feasibility standards, and predictive standards. After reviewing the history, current status, and potential consequences and uses of HR standards, we consider how scholars and researchers might become more involved in the standards-development process. A third section considers whether linkage research and meta-analytic frameworks might inform predictive standards and their relationship to HR standards. We then offer a simple framework and some examples that show where HR evidence and standards do and do not intersect. The final section suggests how researchers could define research questions and describe the implications of their findings in ways that might make research evidence more “feasible at scale” and thus forge a stronger link between research and standard-setting.

Book chapters on the topic "Simultaneous measurement of potential and current":

Zweifach, Adam, Markus Hoth, and Richard S. Lewis. "Simultaneous Measurement of Membrane Current and Intracellular Calcium." In Imaging Living Cells, 140–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-60003-6_6.

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Jiang, Mingqing, Jiangxue Zhang, and Yang Liu. "Measurement and Analysis of Carrying Potential of Natural Resources and Environment." In Current Chinese Economic Report Series, 263–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31597-8_11.

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Eiselt, M., U. Zwiener, F. Gießler, H. Wagner, J. Haueisen, R. Huonker, H. Nowak, and B. Schack. "Intracortical Spread of Epileptic Spikes — Simultaneous Measurement of Magnetic Field and Electric Potential in Rabbits." In Biomag 96, 1098–101. New York, NY: Springer New York, 2000. http://dx.doi.org/10.1007/978-1-4612-1260-7_268.

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Kasemir, H. W. "An Apparatus for Simultaneous Registration of Potential Gradient and Air-Earth Current (Description and First Results)." In Heinz-Wolfram Kasemir: His Collected Works, 577–84. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1002/9781118704813.ch44.

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Koga, Honoka, Jihyoung Lee, Peter Rolfe, Ken-ichi Yamakosh, Akira Kamiya, and Takehiro Yamakoshi. "Evaluation of System for Simultaneous Measurement of Physiological Parameters: Potential for Determination of Age-Related Cardiovascular Status." In IFMBE Proceedings, 1620–23. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-31635-8_199.

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Onnes, H. Kamerlingh. "Further experiments with liquid helium. H. On the electrical resistance of pure metals etc. VII. The potential difference necessary for the electric current through mercury below 4°.19 K." In Through Measurement to Knowledge, 273–314. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-009-2079-8_18.

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Wang, Chaofeng, and Jiaxin Li. "Measurement and Evaluation on China’s Cargo Airlines Network Development." In Proceeding of 2021 International Conference on Wireless Communications, Networking and Applications, 123–38. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2456-9_14.

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AbstractIn view of China’s cargo airlines network, taking the airport of each city as the node and the number of flights between cities as the weight of the side, the network topology index and economic index are used to evaluate the current situation of the network and the development potential of the network. Then, the TOPSIS method is used to comprehensively evaluate China’s cargo airlines network. The results show that the network ranking of each airline is: China Cargo Airlines, SF Airlines, China Post Airlines, Jinpeng Airlines, Longhao Airlines, Yuantong Airlines. Finally, considering the development stage of China’s cargo airlines, the sensitivity analysis is conducted by resetting the weight to verify the effectiveness of TOPSIS method. At the same time, according to the different stages of the network of cargo airlines, some suggestions on the development of the network are given.

Vierra, Nicholas C., Matthew T. Dickerson, Louis H. Philipson, and David A. Jacobson. "Simultaneous Real-Time Measurement of the β-Cell Membrane Potential and Ca2+ Influx to Assess the Role of Potassium Channels on β-Cell Function." In Methods in Molecular Biology, 73–84. New York, NY: Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-7362-0_7.

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Salazar-García, Domingo C., Christina Warinner, Jelmer W. Eerkens, and Amanda G. Henry. "The Potential of Dental Calculus as a Novel Source of Biological Isotopic Data." In Exploring Human Behavior Through Isotope Analysis, 125–52. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-32268-6_6.

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AbstractStable isotope analysis has become an essential tool in investigations of ancient migration and paleodietary reconstruction. Because the biogeochemistry of bone collagen and apatite is well known, current methods rely almost exclusively on analyses of bones and teeth; however, dental calculus represents a potentially additional biological source of isotopic data from ancient skeletons. Dental calculus is a mineralized bacterial biofilm that forms on the surfaces of teeth. Sampling dental calculus does not damage the dentition and thus can be used in cases where it is not possible to perform destructive analyses of conventional mineralized tissues. Like bone and dentine, dental calculus contains both inorganic and organic components, allowing measurement of C, N, O, H, and Sr isotopes. Additionally, dental calculus forms as serial, non-remodeling laminar accretions on the tooth surface, opening up the possibility of analyzing discrete time points during the lifetime of an individual. However, as a microbial biofilm and not a human tissue, the biochemistry of dental calculus is complex, containing multiple calcium phosphate mineral phases, organic and inorganic food remains, hundreds of human and bacterial proteins, and diverse biomolecules from thousands of endogenous bacterial taxa. Isotopic investigation of dental calculus is still in its infancy, and many questions remain regarding its formation and processes of diagenesis. This chapter (1) reviews the unique advantages presented by dental calculus as a novel source of biological isotopic data, (2) critically evaluates published isotopic studies of dental calculus, and (3) explores the current challenges of dental calculus stable isotope analysis through a case study of an Ancient Puebloan Basketmaker II population from the American Southwest.

Comitti, Alessandro, Harikrishnan Vijayakumaran, Mohammad Hosein Nejabatmeimandi, Luis Seixas, Adrian Cabello, Diego Misseroni, Massimo Penasa, et al. "Ultralight Membrane Structures Toward a Sustainable Environment." In Sustainable Structures and Buildings, 17–37. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-46688-5_2.

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AbstractThe building construction industry is the largest anthropogenic source of pollution, with massive energy consumption and substantial CO2 emissions. Lightweight tension structures allow the simultaneous implementation of several sustainable strategies by using recyclable low-carbon structural membranes offering a greener alternative to glass and other cladding materials. Their efficient structural load-bearing mechanisms result in significant weight savings in buildings and a drastic reduction of the environmental impact associated with material production, transportation, use, and disposal. A subgroup of lightweight materials, structural fabrics, and foils has been gaining popularity among designers and architects in recent years because of their desirable features such as high stiffness, strength, ductility, durability, and functional properties. While these structural membranes open new crucial perspectives for the clean energy transition and have been recently employed worldwide, their full potential is still limited by the lack of construction codes, advanced optimization tools, and comprehensive viscous-thermo-mechanical constitutive models. This chapter aims to foster the design of membrane structures by presenting their basic principles and recent advancements in the field. It covers the design approaches, employed materials and efforts in their characterization and modeling, implications on the sustainability of the built environment, current challenges, and future pathways from both academic research and engineering design viewpoints.

Conference papers on the topic "Simultaneous measurement of potential and current":

TOURNEUR, Y., J.-C. BERNENGO, and Y. PACHECO. "SIMULTANEOUS ATP AND MITOCHONDRIAL POTENTIAL MEASUREMENTS IN LIVING CELLS." In Bioluminescence and Chemiluminescence - Progress and Current Applications - 12th International Symposium on Bioluminescence (BL) and Chemiluminescence (CL). WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812776624_0104.

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Wenger, P., S. Abdul Madhar, and M. Beltle. "Simultaneous Electrical, UHF, Current and Optical PD Measurements on Floating Potential under DC Stress." In 2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP). IEEE, 2019. http://dx.doi.org/10.1109/ceidp47102.2019.9010548.

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Park, K. W., Y. B. Cho, K. S. Jeon, S. M. Lee, and Y. T. Kho. "Evaluation of Stray Current Effect on the Cathodic Protection of Underground Pipeline." In 1996 1st International Pipeline Conference. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/ipc1996-1850.

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Two types of stray current which affect the cathodic protection of underground pipeline are discussed. One is the stray current by DC transit system and the other is that originated from the nearby cathodic protection system. The popular evaluation methods of the pipe-to-siol potential measurement was undertaken to evaluate the corrosion activity of pipeline. In case when the pipe was affected by the stray current, the measured pipe-to soil potential was significantly deviated from the mean value resulting in normal distribution. Analysis of such distribution pattern has revealed that the pipe under investigation was in the condition of insufficient protection (noble mean potential and high asymmetry coefficient) due to the considerable effect of stray current (high standard deviation value). It was also confirmed that the efficiency of drainage system was so low (<10%) due to the improper selection of drainage point. Simultaneous measurement of the magnitude and direction of the sheath current resulted in information about the place where stray current entered into pipe and escaped to soil. For the second case of stray current problem, it is shown that it has been caused by the combined interference from nearby CP system.

Wyatt, Lucy R., Mike D. Moorhead, and Iain A. Fairley. "Developments in Metocean HF Radar Technology, Applications and Accuracy." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95202.

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Abstract HF radar surface current measurement is now a well-accepted technology and part of many operational oceanography systems. Although the UK was involved from the early stages in this technology there has not been the take-up seen elsewhere in the world most notably in the US and, more recently, in the Far East where such data are being routinely used for model evaluation and other applications. In addition to surface currents, simultaneous measurement of waves and winds has also been demonstrated although these are still often regarded as experimental and unreliable. This is in part because good quality wave measurement requires much higher quality radar data which is not always available so some published results are rather noisy. This paper will review the current state of the art in all these measurements and highlight some new developments which have the potential to increase their availability, accuracy and scope. The original wave measurement work in the UK was carried out using the Pisces HF radar system which was designed specifically for this application. New measurements using a modification of this radar, which exploits the fact that different radar operating frequencies have different responses to wave conditions, will be presented. Software developments to increase the robustness of HF radar metocean measurements will be discussed.

Ragaller, Paul A., Alexander Sappok, Jie Qiao, Xiaojin Liu, and Jonathan Aguilar. "Direct Simultaneous Measurement of Particulate Matter and Ammonia Storage on Combined Selective Catalytic Reduction Filter Systems Using Radio Frequency Sensors." In ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9528.

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Tightening global emissions regulations are motivating interest in the development and implementation of Selective Catalytic Reduction + Filtration (SCRF) systems, which are designed to reduce the concentration of tailpipe particulate matter (PM) and NOx emissions. These systems allow designers to combine the NOx reduction capability of an SCR with the filtration capability of a particulate filter on a single unit. Practical implementation of these systems requires reliable measurement and diagnosis of their state — both with respect to trapped particulate matter as well as adsorbed ammonia. Currently, these systems rely on a variety of gas sensors, mounted upstream or downstream of the system, that only provide an indirect inference of the operation state. In this study, a single radio frequency (RF) sensor was used to perform simultaneous measurements of soot loading and ammonia inventory on an SCRF. Several SCRF core samples were tested at varying soot and ash loads in a catalyst reactor bench. Soot levels were measured by monitoring changes in the bulk dielectric properties within the catalyst using the sensor, while ammonia levels were determined by feeding selected regions of the RF spectrum into a pretrained generalized regression neural network model. Results show the RF sensor is able to directly measure the instantaneous ammonia inventory, while simultaneously providing soot loading measurements within 0.5 g/L. These results confirm that simultaneous measurements of both the PM and ammonia loading state of an SCRF are possible using a single RF sensor via analysis of specific features in the full RF spectrum. The results indicate significant potential to remove the control barriers typically associated with the implementation of advanced SCRF systems.

Atkins, Nicholas R., Robert J. Miller, and Roger W. Ainsworth. "The Development of Aerodynamic Performance Measurements in a Transient Test Facility." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53813.

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Transient test facilities offer the potential for the simultaneous study of turbine aerodynamic performance, unsteady flow phenomena and the heat transfer characteristics of a turbine stage. This paper describes the development of aerodynamic performance measurement techniques in the Oxford Rotor Facility (ORF). The solutions to the technological issues involved with transient testing presented in this paper are expected to achieve levels of precision uncertainty comparable with traditional steady flow test rigs. The theoretical background to the measurement of aerodynamic performance is presented together with a comprehensive pre-test uncertainty analysis. The instrumentation scheme for the measurement of stage mass flow rate is discussed in detail, the measurements of shaft power, total inlet enthalpy, and stage pressure ratio are also outlined. The current working section features a 62% scale, 1-1/2 stage, high-pressure shroudless transonic turbine. The required inlet flow conditions are provided by an Isentropic Light Piston Tunnel (ILPT) with a quasi-steady state run time of approximately 70ms. The testing is conducted at engine representative specific speed, pressure ratio, gas-to-wall temperature ratio, Mach number and Reynolds number.

Ju, Bing-Feng, Yang Ju, and Masumi Saka. "Development of a New Microscopic Four-Point AFM Probe for the Measurement of Local Electrical Conductivity." In ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems collocated with the ASME 2005 Heat Transfer Summer Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ipack2005-73433.

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A microscopic four-point atomic force microscope (AFM) probe with concomitant experimental technique for local conductivity measurement is presented. A silicon nitride based AFM contact-mode probe with a V-shaped tip, which patterned by using the conventional photolithography method, is selected. The probe is then etched to four parallel isolated electrodes for the purpose of performing current input and electrical potential drop measurement. The new probe not only inherits the function of surface topography generating but also has the capability of characterizing the local conductivity simultaneously. The nanoresolution position control mechanism of AFM allows the probe scanning across micrometers sized area and creating high spatial resolution map of the in-plane conductivities. Experiments have shown the microscopic four-point probe to be mechanically flexible and robust. The repeatable conductivity measurements on the surface of aluminum and indium tin oxide (ITO) thin films indicate the technique has potential application for characterizing the devices and materials in microscale.

Dutta, S. M., M. S. Ramirez, A. Smith, J. Olaiya, L. Friere, and J. Kverneland. "Design of a Novel Sensor for Circumferential Multi Casing Corrosion Measurement Through Tubing." In ADIPEC. SPE, 2023. http://dx.doi.org/10.2118/216512-ms.

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Abstract A novel sensor design is presented that uses transient or pulsed eddy current measurements to perform circumferential quantitative evaluation of corrosion, thickness, or metal loss of two or more concentric tubulars individually. Modeling and simulation studies and experimental results are presented that formed the basis, as well as provided validation, for the sensor design. The new sensor design is based on transient or pulse eddy current technology and comprises several coils that simultaneously achieve azimuthal resolution on the tubing and the casing as well as high radial depth of investigation. The sensor is designed to induce eddy currents in multiple concentric tubulars and to measure a time-varying response from the outward-diffusing eddy currents. The full transient responses from multiple coils within the sensor can then be interpreted to obtain azimuthal information about corrosion and wall thickness of these tubulars. Simulation studies and experimental results are presented that relate different physical features of the sensor to its performance in terms of sensitivity to channel flaws, signal-to-noise ratio, and azimuthal resolution. The results show that the sensor design has the potential to complement conventional multi-casing corrosion measurements that investigate more than three concentric tubulars but only yield average non-azimuthal wall thickness measurements of each tubular. Conventional multi-casing corrosion measurements have most recently been relegated as a precursor to pulling the tubing and evaluating the casing again with single barrier evaluation services. Measurements from the novel sensor could arm the operators with more accurate information as to the azimuthal extent of corrosion on the inner barriers and empower them to make timelier and more economical well integrity management decisions. These measurements can also complement through tubing evaluation of cement behind casing. This paper describes the advantages, limitations, and design of a new state-of-the-art pulsed eddy current sensor that is meant to provide azimuthal measurements of the inner strings in multiple barrier completions. The novel sensor design has the potential to plug a critical gap in conventional downhole well integrity measurements during intervention or plug & abandonment which in present day only provide non-azimuthal multi-casing corrosion, thickness, and metal loss measurements.

Oliver, Sean M., Dmitro J. Martynowych, Matthew J. Turner, David A. Hopper, Ronald L. Walsworth, and Edlyn V. Levine. "Vector Magnetic Current Imaging of an 8 nm Process Node Chip and 3D Current Distributions Using the Quantum Diamond Microscope." In ISTFA 2021. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.istfa2021p0096.

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Abstract The adoption of 3D packaging technology necessitates the development of new approaches to failure electronic device analysis. To that end, our team is developing a tool called the quantum diamond microscope (QDM) that leverages an ensemble of nitrogen vacancy (NV) centers in diamond, achieving vector magnetic imaging with a wide field-of-view and high spatial resolution under ambient conditions. Here, we present the QDM measurement of 2D current distributions in an 8-nm flip chip IC and 3D current distributions in a multi-layer PCB. Magnetic field emanations from the C4 bumps in the flip chip dominate the QDM measurements, but these prove to be useful for image registration and can be subtracted to resolve adjacent current traces in the die at the micron scale. Vias in 3D ICs display only Bx and By magnetic fields due to their vertical orientation and are difficult to detect with magnetometers that only measure the Bz component (orthogonal to the IC surface). Using the multi-layer PCB, we show that the QDM’s ability to simultaneously measure Bx, By, and Bz is advantageous for resolving magnetic fields from vias as current passes between layers. We also show how spacing between conducting layers is determined by magnetic field images and how it agrees with the design specifications of the PCB. In our initial efforts to provide further z-depth information for current sources in complex 3D circuits, we show how magnetic field images of individual layers can be subtracted from the magnetic field image of the total structure. This allows for isolation of signal layers and can be used to map embedded current paths via solution of the 2D magnetic inverse. In addition, the paper also discusses the use of neural networks to identify 2D current distributions and its potential for analyzing 3D structures.

Nelson, David A., Saeed I. Latif, Chad Austin, and Jeremy Chatham. "Feasibility of Using a Printed Microstrip Antenna in Evaluation of Peripheral Microcirculation." In 2018 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/dmd2018-6912.

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Peripheral Artery Disease (PAD) is a widespread and often undiagnosed condition associated with increased incidence of serious cardiovascular events. Current diagnostic tests for PAD may not be adequate for screening the large at-risk population. A new skin blood flow measurement technique using RF heating in the millimeter wave band, with simultaneous surface temperature measurement offers a potential method for screening individuals at risk for PAD quickly and easily. The feasibility of a transducer design incorporating a microstrip antenna and one or more infrared temperature sensors was evaluated in vitro, using a phantom skin material and a custom flow chamber. Results demonstrate the ability to heat the unperfused phantom by up to 7°C in less than 60 s, depending on antenna separation distance from the target surface. At a distance of 2 mm, preliminary results indicate the rate of temperature increase is sensitive to flowrate. These results suggest a possible method for noninvasive screening of individuals for PAD that is quick, easy and inexpensive.

Reports on the topic "Simultaneous measurement of potential and current":

Perdomo and Payer. L51736 Chemical and Electrochemical Conditions on Steel at Disbonded Coatings. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 1995. http://dx.doi.org/10.55274/r0010266.

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The objective of this research was to study the effects of cathodic protection at coating holidays and associated areas of disbondment through simultaneous determination of the electro-chemical reactions and chemical changes taking place in the environment adjacent to the steel substrate. Primary parameters of interest were applied potential, solution conductivity, pH oxygen in solution. The experimental plan was comprised of six interrelated studies involving both laboratory simulations and modeling. It was found that an effective CP system provides sufficient current flow at the exposed steel surface to modify the ground water in the immediate environment by lowering soluble oxygen levels and increasing its alkalinity. Further, corrosion protection is achieved in the shielded areas under the disbonded coating where current flow is minimal, through this chemical modification of the aqueous environment, and it is not necessary that current flow into all of the disbonded region. Three conditions of import to pipeline corrosion protection were also simulated in this investigation. Chemical environment and electric potential distribution within disbond regions were measured for the affects of interruption and reapplication of current; the occurrence of wet/dry cycles at the holiday and the presence of prior corrosion products.

Buchler, M., H. G. Schoneich, and F. Stalder. DRS04BSS Criteria to Assess the Alternating Current Corrosion Risk of Cathodically Protected Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2004. http://dx.doi.org/10.55274/r0011818.

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This paper addresses the assessment of the corrosion risk of a pipeline due to alternating currents. The state of the art technique is the use of coupons, which simulate a coating fault and which allow to measure the ac-current density and also to evaluate corrosion products and pits. Recently, different criteria to assess the corrosion risk have been proposed that are based on the ratio between ac- and dc-current density or the instantaneous off-potential (high-speed off-potential measurement) measured on a coupon. Furthermore, the charge needed to oxidize corrosion products (under alkaline conditions) on a corroded steel surface indicates the level of metal loss. These criteria are discussed on the basis of field experience from coupons and from alternating current-corrosion pits on high voltage interfered pipelines. Results from long term laboratory corrosion measurements under constant AC and DC load are presented which indicate that not only a reduction of pipe/ground AC potential but also a careful adjustment of cathodic protection level helps to minimize a.c. corrosion rates. Based on the results from cyclic potentiodynamic experiments under alkaline conditions, a basic model explaining AC corrosion on cathodically protected pipelines has been developed.

Thompson and Lawson. L51693 Most Accurate Method for Measuring an Off-Potential. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), March 1994. http://dx.doi.org/10.55274/r0010317.

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�During a prior Gas Research Institute (GRI) research program, a spiking phenomenon was identified that prevented the measurement of the off potential directly from the pipe-to-soil potential waveform. Furthermore, the spike made it impossible to measure an off potential during current interruption for some period of time following interruption. In recent years, there has been discussion that the spike in the pipe-to-soil potential waveform affects the ability of the CP system to mitigate corrosion. In addition, the increased significance that has been placed on off-potential measurements within the industry has made it important to understand any phenomenon that may affect the ability to measure the off potential. Because of the above concerns, the Corrosion Supervisory Committee of the Pipeline Research Committee authorized this two-year program to establish the cause and effects of the spiking phenomenon. To accomplish this program, a Work Plan was established that provided for the following four tasks: Task 1 - Field Measurements, Task 2 - Circuit Analog Model, Task 3 - Effect of the Spike on Off- Potential Measurements, and Task 4 - Laboratory Experiments. Through this combined effort of field evaluations, modeling, and laboratory experiments, the root cause of the spike was established along with guidelines for making the off-potential measurement. The results of this project provides the CP engineer with a standard practice for measuring off-potentials in the presence of the spiking phenomenon.

Sharp, Matthew. Revisiting digital inclusion: A survey of theory, measurement and recent research. Digital Pathways at Oxford, April 2022. http://dx.doi.org/10.35489/bsg-dp-wp_2022/04.

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Focusing on the internet as a foundational technology, this paper begins by summarising recent developments in digital inclusion theory, particularly as this relates to developing countries. It sets out a framework of core components of digital inclusion - including ac-cess/use, quality of access/use, affordability, and digital skills - and briefly considers policy implications. The paper then surveys the ways these components are currently measured in household and firm surveys and by international organisations, highlighting some of the often-overlooked weaknesses of current measures, and suggesting possible improvements. The paper also reflects on potential applications of (and risks associated with) new ways of measuring digital inclusion using big data. Lastly, building on the framework developed, the paper reviews the empirical literature on ‘digital divides’ in developing countries, and makes suggestions for how future research could become more rigorous and useful.

Holbrook. L51475 Most Negative Potential Prior to the Onset of Significant Hydrogen Evaluation in a Crevice Task 2. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), May 1985. http://dx.doi.org/10.55274/r0011233.

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Discusses the most negative cathodic protection potential that can be applied before significant evolution of hydrogen gas occurs at a holiday in a line pipe coating and the extent to which SCC is promoted beneath both unblocked and blocked disbonded pipeline coatings due to the decay of the potential distribution along the disbondment. Experiments on hydrogen evolution from exposed steel coupons and measurement of potential and current distributions beneath simulated disbonded pipeline coatings were conducted.

Author, Unknown. L52297 Technologies for In-Service Measurement of Seal Gaps in Internal Floating Roof Tanks. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), June 2009. http://dx.doi.org/10.55274/r0010683.

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The industry need was to investigate current and potential technologies for the measurement of seal gaps in internal floating roof storage tanks, including methods of remote monitoring including a) identify existing seal gap measurement technologies and methodologies as well as individuals and/or companies who own the technologies, and b) identify other technologies that may prove useful to effectively measure seal gaps on tanks in service. Four technologies were identified as possible remote-inspection alternatives to the current general practice of inspecting and measuring internal floating roof seal gaps by placing personnel inside in-service tanks. At least two of these technologies, remote camera and x-ray imaging, are worthy of additional evaluation to assess the relative costs and reliability as alternatives to manual inspection and measurement. Remote camera technology has been applied specifically to seal gap measurement and shown to be a viable alternative to manual inspection. X-ray imaging technology appears to be viable as an alternative but has not been applied specifically to seal gap measurement and would require further development to affirm its suitability for this purpose..

Thompson and Lawson. L51667 Causes and Effects of the Spiking Phenomenon. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 1992. http://dx.doi.org/10.55274/r0010141.

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During a prior research program, a spiking phenomenon was identified that prevented the measurement of the off potential directly from the pipe-to-soil potential waveform. Furthermore, the spike made it impossible to measure an off potential during current interruption for some period of time following interruption. In recent years, there has been discussion that the spike in the pipe-to-soil potential waveform affects the ability of the CP system to mitigate corrosion. In addition, the increased significance that has been placed on off-potential measurements within the industry has made it important to understand any phenomenon that may affect the ability to measure the off potential. This effort works to establish the cause and effects of the spiking phenomenon. To accomplish this program, a Work Plan was established that provided for the following four tasks: Task 1 - Field Measurements, Task 2 - Circuit Analog Model, Task 3 - Effect of the Spike on Off- Potential Measurements, and Task 4 - Laboratory Experiments. Through this combined effort of field evaluations, modeling, and laboratory experiments, the root cause of the spike was established along with guidelines for making the off-potential measurement. The results of this project provides the CP engineer with a standard practice for measuring off-potentials in the presence of the spiking phenomenon.

Gummow. L52106 Cathodic Protection Gap Analysis. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), September 2003. http://dx.doi.org/10.55274/r0011098.

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This report contains the results of a review of the cathodic protection research literature on pipelines, published over the last 20 years, with the primary objective to identify areas of cathodic protection technology that require further research efforts. Over 100 research reports and papers were examined, most of which were PRCI sponsored projects. The summary, conclusions, and recommendations of the research reports are included in key word searchable form. A synopsis of the more significant projects is included along with reasoned recommendations for additional research on 15 topics summarized in typical PRCI request-for-proposal format. The recommended research projects, some of which overlap, cover the following areas of interest: development of CP design models, CP design fundamentals such as criteria, current distribution, and current requirements, pipeline potential measurement techniques, stray current interference, and cathodic disbondment/shielding of protective coatings.

Gummow. L51908 AC Grounding Effects on Cathodic Protection Performance in Pipeline Stations.pdf. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2001. http://dx.doi.org/10.55274/r0010269.

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Most AC powered equipment at pipeline stations and at motorized valve sites isrequired, by code, to be electrically grounded to one or more ground electrodes. These grounding systems are normally electrically bonded to the AC power distribution grid, which can be quite extensive. Piping, either intentionally or inadvertently, is often connected to the AC electrical grounding grid in pipeline stations. Grounding grid conductors are usually bare and composed of copper or tinned copper, and ground rod materials can consist of a wide variety of metals such as copper-clad steel, carbon steel, stainless steel, galvanized steel, and galvanic anode alloys of zinc and magnesium. The interconnection of these grounding materials to the piping can increase the current requirements of the cathodic protection system, distort the current distribution pattern and complicate the accurate measurement of the pipe potentials. Benefit: The primary objective of this research project was to assess the impact of various types of grounding materials on the performance and testing of cathodic protection systems. The two major issues in this regard were the effects on current requirements and the accuracy of pipe-to-soil potential measurements. In addition, some related issues investigated as follows:the electrical resistance of each groundrod-to-earth was to be measured to determine whether or not there were any changes in the resistance-to-earth as a result cathodic polarization;the potential of galvanized steel was to be measured with increasing zinc consumption to determine if there is a well defined relationship between potential and zinc consumption; the National Electrical Code (NEC) was to be reviewed with respect to the insertion of AC coupling/DC isolating devices in series between the piping and the electrical grounding network. The results of this investigation were intended toprovide information to design more effective cathodic protection facilities for piping in pipeline stations having electrical grounding systems, anddetermine whether or not the resistance of the electrical grounding system increases as a result of receiving cathodic protection, andrecommend pipe-to-soil potential survey techniques to maximize measurement accuracy in the presence of an AC grounding grid, andevaluate the use of DC isolators/AC couplers to interconnect the piping to either the secondary or primary AC grounding system.

Ham, Andrés, Angela Guarin, and Juanita Ruiz. How Accurately are Household Surveys Measuring the Size and Inequalities for the LGBT Population in Bogota, Colombia? Evidence from a List Experiment. Inter-American Development Bank, February 2023. http://dx.doi.org/10.18235/0004721.

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This paper studies whether household surveys precisely identify the LGBT population and are suitable to measure labor market discrimination in Colombia. We first quantify the size of the LGBT population and estimate labor market inequalities from these data, highlighting potential pitfalls from using this approach. We then present findings from a list experiment in Bogotá, Colombia. Results show that household surveys underestimate the size of the LGBT population and may yield biased estimates of labor market inequalities. While survey estimates range between 1-4%, we find that LGBT people constitutes around 12-22% of the total population. We find heterogeneous reporting by sex, age groups, educational attainment, and marital status. Our findings suggest that while current measurement practices are a step forward for the LGBT populations statistical visibility, additional steps are required before household surveys may be used to consistently estimate discrimination and guide policy responses to protect this population.

Academic literature on the topic 'Simultaneous measurement of potential and current'

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Journal articles on the topic "Simultaneous measurement of potential and current":

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Conference papers on the topic "Simultaneous measurement of potential and current":

Reports on the topic "Simultaneous measurement of potential and current":