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1

Modeling deep brain stimulation: point source approximation versus realistic representation of the electrode  

NASA Astrophysics Data System (ADS)

Deep brain stimulation (DBS) has emerged as an effective treatment for movement disorders; however, the fundamental mechanisms by which DBS works are not well understood. Computational models of DBS can provide insights into these fundamental mechanisms and typically require two steps: calculation of the electrical potentials generated by DBS and, subsequently, determination of the effects of the extracellular potentials on neurons. The objective of this study was to assess the validity of using a point source electrode to approximate the DBS electrode when calculating the thresholds and spatial distribution of activation of a surrounding population of model neurons in response to monopolar DBS. Extracellular potentials in a homogenous isotropic volume conductor were calculated using either a point current source or a geometrically accurate finite element model of the Medtronic DBS 3389 lead. These extracellular potentials were coupled to populations of model axons, and thresholds and spatial distributions were determined for different electrode geometries and axon orientations. Median threshold differences between DBS and point source electrodes for individual axons varied between -20.5% and 9.5% across all orientations, monopolar polarities and electrode geometries utilizing the DBS 3389 electrode. Differences in the percentage of axons activated at a given amplitude by the point source electrode and the DBS electrode were between -9.0% and 12.6% across all monopolar configurations tested. The differences in activation between the DBS and point source electrodes occurred primarily in regions close to conductor-insulator interfaces and around the insulating tip of the DBS electrode. The robustness of the point source approximation in modeling several special cases—tissue anisotropy, a long active electrode and bipolar stimulation—was also examined. Under the conditions considered, the point source was shown to be a valid approximation for predicting excitation of populations of neurons in response to DBS.

Zhang, Tianhe C.; Grill, Warren M.

2010-12-01

2

Material and Electrode Preparation Study of Air Electrode.  

National Technical Information Service (NTIS)

The optimum structure and materials for the gas diffusion layer of air electrodes for alkaline fuel cells was studied by long run test of different materials. These pellets and the two tube air electrodes contain carbon black, and polytetrafluorethylene a...

E. Gocheva-Huikko J. Lamminen T. Noponen

1995-01-01

3

Electrode Passivation Studies.  

National Technical Information Service (NTIS)

The operation of primary, reserve batteries in a passive mode was explored. An anode can be put into the passive state by an appropriate electrical pulse and can be maintained in this condition by suitable connection to the positive battery electrode. Act...

S. B. Brummer A. C. Makrides A. J. Bradspies

1967-01-01

4

Stainless Steel MicroNeedle Electrodes Made by Electrolytic Pointing  

Microsoft Academic Search

Micro-needle electrodes of any desired taper and sharpness for insertion into living tissue can be made quickly by electrolytic etching. For stainless steel wire the electrolyte is a mixture of sulfuric and ortho-phosphoric acids. The wire to be pointed is made the anode of a circuit initially carrying about 0.03 amp. Gross shaping of the needle is done by repeatedly

Harry Grundfest; Robert W. Sengstaken; Walter H. Oettinger; R. W. Gurry

1950-01-01

5

Electrode Passivation Studies.  

National Technical Information Service (NTIS)

Studies of the passivation of Zn-Fe, Zn-Mn, Zn-Co, and Zn-Ni alloys were made potentiostatically. Alloys of 90 Zn 10 Fe corrode at a high rate even when passive. Alloys of 83Zn-17 Mn have low, active dissolution currents. The 89 Zn - 11 Co alloys have hig...

S. B. Brummer A. C. Makrides J. Bradspies

1966-01-01

6

Experimental study of cylindrical air electrodes  

NASA Astrophysics Data System (ADS)

The electrodes studied here are cylindrical and prepared to be placed inside the inner surface of a sintered brass tube, which is nickel-plated. Previously we have reported on the preparation of flat air electrodes and also on long run tests carried out with these electrodes. The electrode material was prepared by the so-called wet method to obtain a carbon dough which is easy to handle. The material preparation remains the same, but owing to the different geometrical shape, the preparation of the electrode itself is quite different. We have studied here the long-term performance of these new cylindrical air electrodes and at the same time measured the carbonate content of the electrolyte. We have also analyzed by comparative methods which property of the electrode lowers the performance after a fairly long period.

Viitanen, M.; Lamminen, J.; Lampinen, M. J.

1991-11-01

7

Chronic Oxygen Electrodes - A Feasibility Study.  

National Technical Information Service (NTIS)

The feasibility of obtaining stable oxygen electrodes by coating with a plasma catalyzed polymer film was studied. These electrodes are to be used for chronic in vivo measurement of tissue oxygen tension. The application of the film was tested on both dis...

A. W. Hahn K. G. Mayhan R. E. Barr

1972-01-01

8

Atlas of the muscle motor points for the lower limb: implications for electrical stimulation procedures and electrode positioning.  

PubMed

The aim of the study was to investigate the uniformity of the muscle motor point location for lower limb muscles in healthy subjects. Fifty-three subjects of both genders (age range: 18-50 years) were recruited. The muscle motor points were identified for the following ten muscles of the lower limb (dominant side): vastus medialis, rectus femoris, and vastus lateralis of the quadriceps femoris, biceps femoris, semitendinosus, and semimembranosus of the hamstring muscles, tibialis anterior, peroneus longus, lateral and medial gastrocnemius. The muscle motor point was identified by scanning the skin surface with a stimulation pen electrode and corresponded to the location of the skin area above the muscle in which an electrical pulse evoked a muscle twitch with the least injected current. For each investigated muscle, 0.15 ms square pulses were delivered through the pen electrode at low current amplitude (<10 mA) and frequency (2 Hz). 16 motor points were identified in the 10 investigated muscles of almost all subjects: 3 motor points for the vastus lateralis, 2 motor points for rectus femoris, vastus medialis, biceps femoris, and tibialis anterior, 1 motor point for the remaining muscles. An important inter-individual variability was observed for the position of the following 4 out of 16 motor points: vastus lateralis (proximal), biceps femoris (short head), semimembranosus, and medial gastrocnemius. Possible implications for electrical stimulation procedures and electrode positioning different from those commonly applied for thigh and leg muscles are discussed. PMID:21796408

Botter, Alberto; Oprandi, Gianmosè; Lanfranco, Fabio; Allasia, Stefano; Maffiuletti, Nicola A; Minetto, Marco Alessandro

2011-07-28

9

Response to high-energy photons of PTW31014 PinPoint ion chamber with a central aluminum electrode  

Microsoft Academic Search

Since its introduction the PinPoint (PTW-Freiburg) micro-ionization chamber has been proposed for relative dosimetry (output factors, depth dose curves, and beam profiles) as well as for determination of absolute dose of small high-energy photon beams. This paper investigates the dosimetric performance of a new design (type 31014) of the PinPoint ion chamber with a central aluminum electrode. The study included

S. Agostinelli; S. Garelli; M. Piergentili; F. Foppiano

2008-01-01

10

Imaging study on acupuncture points  

Microsoft Academic Search

The topographic structures of acupuncture points were investigated by using the synchrotron radiation based Dark Field Image (DFI) method. Four following acupuncture points were studied: Sanyinjiao, Neiguan, Zusanli and Tianshu. We have found that at acupuncture point regions there exists the accumulation of micro-vessels. The images taken in the surrounding tissue out of the acupuncture points do not show such

X H Yan; X Y Zhang; C L Liu; R S Dang; M Ando; H Sugiyama; H S Chen; G H Ding

2009-01-01

11

Bright point study  

SciTech Connect

Transition region and coronal observations of bright points by instruments aboard the Solar Maximum Mission and high resolution photospheric magnetograph observations on September 11, 1980 are presented. A total of 31 bipolar ephemeral regions were found in the photosphere from birth in 9.3 hours of combined magnetograph observations from three observatories. Two of the three ephemeral regions present in the field of view of the Ultraviolet Spectrometer-Polarimeter were observed in the C IV 1548 line. The unobserved ephemeral region was determined to be the shortest-lived (2.5 hr) and lowest in magnetic flux density (13G) of the three regions. The Flat Crystal Spectrometer observed only low level signals in the O VIII 18.969 A line, which were not statistically significant to be positively identified with any of the 16 ephemeral regions detected in the photosphere. In addition, the data indicate that at any given time there lacked a one-to-one correspondence between observable bright points and photospheric ephemeral regions, while more ephemeral regions were observed than their counterparts in the transition region and the corona.

Tang, F.; Harvey, K.; Bruner, M.; Kent, B.; Antonucci, E.

1982-01-01

12

Carbon nanotube growth on a pointed bulk electrode using femtosecond laser nonlinear lithography  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT) bundles were synthesized on pointed bulk electrodes using femtosecond laser nonlinear lithography. A resist mask of 1.5 ?m diameter was formed on a pointed bulk cathode by translating a laser focus three-dimensionally inside the spherical photoresist. Metal masks obtained by pattern transfers of the resists effectively suppressed CNT growth during plasma-enhanced chemical vapor deposition, resulting in synthesis of CNT bundles only at the electrode tip. Irradiation of field emission currents from the pointed cathode enables local melting and subsequent removal of anode materials. The damaged region size and the threshold voltage for this removal process were reduced by spatial limitations of emission sites using the metal mask.

Nishiyama, Hiroaki; Iba, Tomohiro; Hirata, Yoshinori

2013-11-01

13

Ion-selective Electrodes in the Study of Cholinesterases  

NASA Astrophysics Data System (ADS)

This review is devoted to the application of various types of ion-selective electrodes in the study of the activities and catalytic properties of cholinesterases and also in chemical analysis with participation of these enzymes. Studies using a membrane "substrate" electrode, a glass pH electrode, an oxidation-reduction platinum electrode, and a polycrystalline electrode based on silver sulphide are considered. Investigations using enzyme electrodes based on immobilised cholinesterases are also described. The advantages and disadvantages of individual methods employing different types of ion-selective electrodes are discussed. The bibliography includes 66 references.

Materova, E. A.; Nikol'skaya, E. B.

1980-10-01

14

Super-resolution imaging using multi- electrode CMUTs: theoretical design and simulation using point targets.  

PubMed

This paper investigates a low computational cost, super-resolution ultrasound imaging method that leverages the asymmetric vibration mode of CMUTs. Instead of focusing on the broadband received signal on the entire CMUT membrane, we utilize the differential signal received on the left and right part of the membrane obtained by a multi-electrode CMUT structure. The differential signal reflects the asymmetric vibration mode of the CMUT cell excited by the nonuniform acoustic pressure field impinging on the membrane, and has a resonant component in immersion. To improve the resolution, we propose an imaging method as follows: a set of manifold matrices of CMUT responses for multiple focal directions are constructed off-line with a grid of hypothetical point targets. During the subsequent imaging process, the array sequentially steers to multiple angles, and the amplitudes (weights) of all hypothetical targets at each angle are estimated in a maximum a posteriori (MAP) process with the manifold matrix corresponding to that angle. Then, the weight vector undergoes a directional pruning process to remove the false estimation at other angles caused by the side lobe energy. Ultrasound imaging simulation is performed on ring and linear arrays with a simulation program adapted with a multi-electrode CMUT structure capable of obtaining both average and differential received signals. Because the differential signals from all receiving channels form a more distinctive temporal pattern than the average signals, better MAP estimation results are expected than using the average signals. The imaging simulation shows that using differential signals alone or in combination with the average signals produces better lateral resolution than the traditional phased array or using the average signals alone. This study is an exploration into the potential benefits of asymmetric CMUT responses for super-resolution imaging. PMID:24158286

2013-11-01

15

Dynamic Characteristics Of Corona Discharges In Point-Plane Electrode Topologies Influenced By Space Charge  

Microsoft Academic Search

The paper presents an analytical analysis of the steady state current-voltage characteristics of corona discharges in point-plane electrode configurations. The paper also discusses the dynamic impulse characteristics of corona discharges based on the solution of the Poisson and the continuity equations which includes the displacement current due to time-varying electric field. The hyperboloid approximation is used to describe the IV

I. V. Timoshkin; S. J. MacGregor; M. J. Given; J. R. Beveridge; J. M. Lehr

2008-01-01

16

Chemically modified electrodes and related solution studies  

SciTech Connect

This report briefly discusses work done in the following areas of chemically modified electrodes: Spectroscopic studies of the modes of interactions of pyridine containing ligands with metal surfaces; attempted synthesis of gem-dihalide containing polymers for attachment of Mo{sub 2}S{sub 4} clusters; Synthesis of oxo-ruthenium dimer complexes as catalysts for H{sub 2} oxidation; and, studies of porphyrin based polymers which catalyze the oxidation (oxygenation) of olefins and benzylic carbons. (JDL)

Elliott, C.M.

1990-01-01

17

A comparison study of electrodes for neonate electrical impedance tomography.  

PubMed

Electrical impedance tomography (EIT) is an imaging technique that has the potential to be used for studying neonate lung function. The properties of the electrodes are very important in multi-frequency EIT (MFEIT) systems, particularly for neonates, as the skin cannot be abraded to reduce contact impedance. In this work, the impedance of various clinical electrodes as a function of frequency is investigated to identify the optimum electrode type for this application. Six different types of self-adhesive electrodes commonly used in general and neonatal cardiology have been investigated. These electrodes are Ag/AgCl electrodes from the Ambu Cardiology Blue sensors range (BR, NF and BRS), Kendall (KittyCat and ARBO) and Philips 13953D electrodes. In addition, a textile electrode without gel from Textronics was tested on two subjects to allow comparison with the hydrogel-based electrodes. Two- and four-electrode measurements were made to determine the electrode-interface and tissue impedances, respectively. The measurements were made on the back of the forearm of six healthy adult volunteers without skin preparation with 2.5 cm electrode spacing. Impedance measurements were carried out using a Solartron SI 1260 impedance/gain-phase analyser with a frequency range from 10 Hz to 1 MHz. For the electrode-interface impedance, the average magnitude decreased with frequency, with an average value of 5 kOmega at 10 kHz and 337 Omega at 1 MHz; for the tissue impedance, the respective values were 987 Omega and 29 Omega. Overall, the Ambu BRS, Kendall ARBO and Textronics textile electrodes gave the lowest electrode contact impedance at 1 MHz. Based on the results of the two-electrode measurements, simple RC models for the Ambu BRS and Kendall-ARBO and Textronics textile electrodes have been derived for MFEIT applications. PMID:19491443

Rahal, Mohamad; Khor, Joo Moy; Demosthenous, Andreas; Tizzard, Andrew; Bayford, Richard

2009-06-02

18

Study of the electrode gap influence on electrode erosion under the action of an electric arc  

Microsoft Academic Search

In this paper we present an experimental study concerning electrode erosion under the sole action of an electric arc. An experimental device allowing to generate electric arc current pulses of constant intensity has been realized. It allows also to ignite the arc for a given electrode gap up to 10 mm by means of a HV discharge. The influence of

A. M. Gouega; Ph. Teste; R. Andlauer; T. Leblanc; J.-P. Chabrerie

2000-01-01

19

Chemically modified electrodes and related solution studies  

SciTech Connect

Studies have been conducted in the following areas: (1) development of a better theoretical understanding of charge transport processes in various conducting polymers, (2) extension of the study of heteropolynuclear Fe/4Ru porphyrin complexes, including an electrochemically polymerizable version which forms polymer films capable of catalyzing the electrochemical oxidation of many olefins, (3) synthesis of several soluble polymers containing gem-dihalides for use in the preparation of polymer-bound dinuclear molybdenum sulfur complexes for electrocatalytic hydrogenations, (4) studies have continued with electronically conducting films made from ester-substituted bipyridine complexes of ruthenium, and (5) we have attempted, in conjunction with 1, 2 and 4, above to develop a better understanding of the structural details of various electrode bound polymer films. 9 refs.

Elliott, C.M.

1989-01-01

20

Study of the contributions of the electrode materials to the plasma of a high-current vacuum spark  

SciTech Connect

The contribution of the electrode material to the formation of the plasma of a low-inductive high-current vacuum spark and its influence on the process of discharge micropinching were studied using X-ray spectroscopy and laser diagnostics. Electrode system configurations are determined in which the contributions of the materials of both electrodes to the plasma emitting X-rays are comparable and in which the contribution of one electrode is dominating. It is found that discharge pinching occurs primarily in the vapor of the pointed electrode independently of its polarity. The experimental results indicate the formation of a suprathermal electron beam in the micropinch region.

Bashutin, O. A.; Vovchenko, E. D.; Dodulad, E. I.; Savjolov, A. S.; Sarantsev, S. A. [National Nuclear Research University Moscow Engineering Physics Institute (Russian Federation)

2012-03-15

21

Study of the electrode gap influence on electrode erosion under the action of an electric arc  

NASA Astrophysics Data System (ADS)

In this paper we present an experimental study concerning electrode erosion under the sole action of an electric arc. An experimental device allowing to generate electric arc current pulses of constant intensity has been realized. It allows also to ignite the arc for a given electrode gap up to 10 mm by means of a HV discharge. The influence of several parameters on the electrode erosion has then been studied. These parameters are: the nature of the contact material (Ag, AgSnO2, AgCdO, Cu, CuSnO2), the value of the electrode gap, the nature of the cover gas... Films realized with the help of a high speed framing camera have brought interesting elements of interpretation concerning the test erosion results.

Gouega, A. M.; Teste, Ph.; Andlauer, R.; Leblanc, T.; Chabrerie, J.-P.

2000-08-01

22

Point-Process Analysis of Neural Spiking Activity of Muscle Spindles Recorded from Thin-Film Longitudinal Intrafascicular Electrodes  

PubMed Central

Recordings from thin-film Longitudinal Intra-Fascicular Electrodes (tfLIFE) together with a wavelet-based de-noising and a correlation-based spike sorting algorithm, give access to firing patterns of muscle spindle afferents. In this study we use a point process probability structure to assess mechanical stimulus-response characteristics of muscle spindle spike trains. We assume that the stimulus intensity is primarily a linear combination of the spontaneous firing rate, the muscle extension, and the stretch velocity. By using the ability of the point process framework to provide an objective goodness of fit analysis, we were able to distinguish two classes of spike clusters with different statistical structure. We found that spike clusters with higher SNR have a temporal structure that can be fitted by an inverse Gaussian distribution while lower SNR clusters follow a Poisson-like distribution. The point process algorithm is further able to provide the instantaneous intensity function associated with the stimulus-response model with the best goodness of fit. This important result is a first step towards a point process decoding algorithm to estimate the muscle length and possibly provide closed loop Functional Electrical Stimulation (FES) systems with natural sensory feedback information.

Citi, Luca; Djilas, Milan; Azevedo-Coste, Christine; Yoshida, Ken; Brown, Emery N.; Barbieri, Riccardo

2012-01-01

23

Point-process analysis of neural spiking activity of muscle spindles recorded from thin-film longitudinal intrafascicular electrodes.  

PubMed

Recordings from thin-film Longitudinal Intra-Fascicular Electrodes (tfLIFE) together with a wavelet-based de-noising and a correlation-based spike sorting algorithm, give access to firing patterns of muscle spindle afferents. In this study we use a point process probability structure to assess mechanical stimulus-response characteristics of muscle spindle spike trains. We assume that the stimulus intensity is primarily a linear combination of the spontaneous firing rate, the muscle extension, and the stretch velocity. By using the ability of the point process framework to provide an objective goodness of fit analysis, we were able to distinguish two classes of spike clusters with different statistical structure. We found that spike clusters with higher SNR have a temporal structure that can be fitted by an inverse Gaussian distribution while lower SNR clusters follow a Poisson-like distribution. The point process algorithm is further able to provide the instantaneous intensity function associated with the stimulus-response model with the best goodness of fit. This important result is a first step towards a point process decoding algorithm to estimate the muscle length and possibly provide closed loop Functional Electrical Stimulation (FES) systems with natural sensory feedback information. PMID:22254803

Citi, Luca; Djilas, Milan; Azevedo-Coste, Christine; Yoshida, Ken; Brown, Emery N; Barbieri, Riccardo

2011-01-01

24

Diamond electrodes for neurodynamic studies in Aplysia californica  

Microsoft Academic Search

As part of an ongoing effort to demonstrate that diamond is a versatile electrode material for biological applications, we present our progress in the development of diamond electrodes for the study of neurodynamics in an animal model, Aplysia californica. Diamond provides a unique opportunity to integrate neural stimulation and sensing in the same implantable device. Data from several parallel studies

Jeffrey M. Halpern; Songtao Xie; Greg P. Sutton; Bryan T. Higashikubo; Cynthia A. Chestek; Hui Lu; Hillel J. Chiel; Heidi B. Martin

2006-01-01

25

Study of Imploding Liner - Electrode Wall Interaction.  

National Technical Information Service (NTIS)

The report gives the results of the experiments on aluminum liner acceleration and their interaction with electrode walls. The liners having the radius of 30 mm, wall thickness of 1mm and 0.7 mm and a length of 30 mm are accelerated by a magnetic field, c...

V. K. Chernyshev Y. I. Zharinov I. D. Kudolkin V. N. Ruzin A. I. Ionov

1994-01-01

26

Electrode Mounting for Potentiostatic Anodic Polarization Studies.  

National Technical Information Service (NTIS)

Samples of an arc melted, 10Cr- 10Ni- Fe alloy were mounted with the Stern-Makrides compression gasket assembly. Some electrodes were mounted directly, others were partially encased or coated with various resins prior to mounting. Potentiostatic anodic po...

N. D. Greene W. D. France B. E. Wilde

1965-01-01

27

Point of zero potential of single-crystal electrode/inert electrolyte interface.  

PubMed

Most of the environmentally important processes occur at the specific hydrated mineral faces. Their rates and mechanisms are in part controlled by the interfacial electrostatics, which can be quantitatively described by the point of zero potential (PZP). Unfortunately, the PZP value of specific crystal face is very difficult to be experimentally determined. Here we show that PZP can be extracted from a single-crystal electrode potentiometric titration, assuming the stable electrochemical cell resistivity and lack of specific electrolyte ions sorption. Our method is based on determining a common intersection point of the electrochemical cell electromotive force at various ionic strengths, and it is illustrated for a few selected surfaces of rutile, hematite, silver chloride, and bromide monocrystals. In the case of metal oxides, we have observed the higher PZP values than those theoretically predicted using the MultiSite Complexation Model (MUSIC), that is, 8.4 for (001) hematite (MUSIC-predicted ~6), 8.7 for (110) rutile (MUSIC-predicted ~6), and about 7 for (001) rutile (MUSIC-predicted 6.6). In the case of silver halides, the order of estimated PZP values (6.4 for AgCl<6.5 for AgBr) agrees well with sequence estimated from the silver halide solubility products; however, the halide anions (Cl(-), Br(-)) are attracted toward surface much stronger than the Ag(+) cations. The observed PZPs sequence and strong anions affinity toward silver halide surface can be correlated with ions hydration energies. Presented approach is the complementary one to the hysteresis method reported previously [P. Zarzycki, S. Chatman, T. Preo?anin, K.M. Rosso, Langmuir 27 (2011) 7986-7990]. A unique experimental characterization of specific crystal faces provided by these two methods is essential in deeper understanding of environmentally important processes, including migration of heavy and radioactive ions in soils and groundwaters. PMID:22277245

Zarzycki, Piotr; Preo?anin, Tajana

2012-01-08

28

Chemically modified electrodes and related solution studies  

SciTech Connect

This report is divided into 5 sections: Ru[sub 4]/Fe complexes of tetra(4[prime]-methyl-2,2[prime]-bipyridine)porphyrin--catalytic epoxidation of olefins; water oxidation catalysis by doubly linked [mu]-oxo ruthenium complexes; polymer films formed by oxidation of transition metal electrodes into solutions of bisbipyridinealkane ligands; polymer films containing [CpMo([mu]-S)][sub 2]S[sub 2]CHR dinuclear clusters;and conducting polymer films for catalyst incorporation.

Elliott, C.M.

1993-04-01

29

Study of polymer-magnetic electrode interfaces using XPS  

NASA Astrophysics Data System (ADS)

Organic spintronics studies spin carrier transportation through organic semiconductors. Understanding how to control this spin current within devices is an important step forward within the research area. The study of the interfaces between the magnetic electrodes and the organic semiconductor (known as the "spinterface") to obtain efficient carrier injection and extraction is important. In this work, the bonding at the spinterface between the magnetic electrode and the polymer regio-regular poly(3-hexylthiophene) (RR-P3HT) has been studied using x-ray photoelectron spectroscopy (XPS). It was found that the bonding between the magnetic electrode and the RR-P3HT depended on both the nature of the magnetic electrode and the solvent used to spin-coat the RR-P3HT. The results are collated with the magnetoresistance measurements made on polymeric spin valve devices.

Morley, N. A.; Qahtani, H. R. H. Al; Hodges, M. H.; Gibbs, M. R. J.; Grell, M.; Dediu, V.; Morgan, D. J.

2013-01-01

30

A study of electrode passivation during aqueous phenol electrolysis  

Microsoft Academic Search

The process of electrode passivation during phenol electrolysis at a platinum electrode was studied in a sulfuric acid electrolyte (pH0-1). Passive film growth and the effects of concentration and potential were investigated using chronoamperometry, x-ray photoelectron spectroscopy, and gel permeation chromatography. The main products of the phenol oxidation are oligomers\\/polymers with weight-averaged molecular weights typically around 1000 g\\/mol after a

M. Gattrell; D. W. Kirk

1993-01-01

31

Response to high-energy photons of PTW31014 PinPoint ion chamber with a central aluminum electrode  

SciTech Connect

Since its introduction the PinPoint (PTW-Freiburg) micro-ionization chamber has been proposed for relative dosimetry (output factors, depth dose curves, and beam profiles) as well as for determination of absolute dose of small high-energy photon beams. This paper investigates the dosimetric performance of a new design (type 31014) of the PinPoint ion chamber with a central aluminum electrode. The study included characterization of inherent and radiation-induced leakage, ion collection efficiency and polarity effect, relative response of the chamber, measurement of beam profiles, and depth dose curves. The 6 and 15 MV photon beams of a Varian 2100 C/D were considered. At the nominal operating voltage of 400 V the PinPoint type 31014 chamber was found to present a strong field size dependence of the polarity correction factor and an excess of the collected charge, which can lead to an underestimation of the collection efficiency if determined with the conventional ''two-voltage'' method. In comparison to the original PinPoint design (type 31006) the authors found for type 31014 chamber no overresponse to large-area fields if polarity correction is applied. If no correction is taken into consideration, the authors found the chamber's output to be inaccurate for large-area fields (0.5% accuracy limited up to the 12x12 and 20x20 cm{sup 2} field for the 6 and 15 MV beams, respectively), which is a direct consequence of the stem and polarity effects due to the chamber's very small sensitive volume (0.015 cc) and cable irradiation. Beam profiles and depth dose curves measured with type 31014 PinPoint chamber for small and medium size fields were compared to data measured with a 0.125 cc ion chamber and with high-resolution Kodak EDR2 films. Analysis of the penumbra (80%-20% distance) showed that the spatial resolution of type 31014 PinPoint ion chamber approaches (penumbra broadening {<=}0.6 mm) EDR2 film results.

Agostinelli, S.; Garelli, S.; Piergentili, M.; Foppiano, F. [S. S. Fisica Medica, National Cancer Research Institute, 16132 Genova (Italy)

2008-07-15

32

Electrochemical charge transfer at a metallic electrode: A simulation study  

SciTech Connect

The calculation of the Marcus free energy curves for electron transfer events between a redox species and a metallic electrode in an atomistic simulation designed to model the electrochemical interface with an ionic liquid is described. The calculation is performed on a system comprising a molten salt mixture confined between model metallic electrodes [Reed et al., J. Chem. Phys. 126, 084704 (2007)] which are maintained at a constant electrical potential. The calculation therefore includes a self-consistent description of the screening of the electrode potential by the liquid and the polarization of the electrode by the ions (image charge effects). The purpose of the study was to examine how the Marcus curves depend on the applied potential and on the distance of the redox species from an electrode. The pronounced oscillations in the mean electrical potential seen in molten salt systems in the ''double-layer'' region are not reflected in the reaction free energy for the electron transfer event. The reorganization energy depends markedly on the distance of the redox ion from the electrode surface because of image charge effects.

Reed, Stewart K.; Madden, Paul A. [School of Chemistry, University of Edinburgh, Edinburgh EH9 3JJ (United Kingdom); Papadopoulos, Aristides [Edinburgh Parallel Computer Centre, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)

2008-03-28

33

Electrochemical charge transfer at a metallic electrode: a simulation study.  

PubMed

The calculation of the Marcus free energy curves for electron transfer events between a redox species and a metallic electrode in an atomistic simulation designed to model the electrochemical interface with an ionic liquid is described. The calculation is performed on a system comprising a molten salt mixture confined between model metallic electrodes [Reed et al., J. Chem. Phys. 126, 084704 (2007)] which are maintained at a constant electrical potential. The calculation therefore includes a self-consistent description of the screening of the electrode potential by the liquid and the polarization of the electrode by the ions (image charge effects). The purpose of the study was to examine how the Marcus curves depend on the applied potential and on the distance of the redox species from an electrode. The pronounced oscillations in the mean electrical potential seen in molten salt systems in the "double-layer" region are not reflected in the reaction free energy for the electron transfer event. The reorganization energy depends markedly on the distance of the redox ion from the electrode surface because of image charge effects. PMID:18376954

Reed, Stewart K; Madden, Paul A; Papadopoulos, Aristides

2008-03-28

34

The development of a micropatterned electrode for studies of zinc electrodeposition  

SciTech Connect

A micropatterned electrode was prepared for the study of electrocrystallization. Using microphotolithography, in conjunction with evaporation and pulse electrodeposition of thin films, a set of artificially roughened electrodes with hemispherical surface features five microns in diameter was developed. Voltammetric studies were conducted to determine the best electrode material. Gold, platinum, and various carbon surfaces were evaluated for zinc nucleation density and hydrogen overpotential. Surface homogeneity was examined by both light and scanning electron microscopy. Gold was determined to possess the best combination of material properties: chemical inertness, low melting point, and a high work function allowing underpotential deposition of zinc which reduces the rate of hydrogen evolution. Stripping coulometry was employed to determine zinc limiting currents, and evaluate effective diffusion coefficients in concentrated zinc chloride solutions. Although the method worked well for dilute zinc chloride and copper sulfate solutions, it failed at higher current densities; the emergence of surface roughness obscured actual limiting current plateaus.

Sutija, D.P.; Muller, R.H.; Tobias, C.W.

1986-12-01

35

Pressure-independent point in current-voltage characteristics of coplanar electrode microplasma devices operated in neon  

SciTech Connect

We introduce the idea of a pressure-independent point (PIP) in a group of current-voltage curves for the coplanar electrode microplasma device (CEMPD) at neon pressures ranging from 15 to 95 kPa. We studied four samples of CEMPDs with different sizes of the microcavity and observed the PIP phenomenon for each sample. The PIP voltage depends on the area of the microcavity and is independent of the height of the microcavity. The PIP discharge current, I{sub PIP}, is proportional to the volume (Vol) of the microcavity and can be expressed by the formula I{sub PIP}=I{sub PIP0}+DxVol. For our samples, I{sub PIP0} (the discharge current when Vol is zero) is about zero and D (discharge current density) is about 3.95 mA mm{sup -3}. The error in D is 0.411 mA mm{sup -3} (less than 11% of D). When the CEMPD operates at V{sub PIP}, the discharge current is quite stable under different neon pressures.

Meng Lingguo; Lin Zhaojun [School of Physics, Shandong University, Jinan 250100 (China); Xing Jianping [School of Information Science and Engineering, Shandong University, Jinan 250100 (China); Liang Zhihu; Liu Chunliang [Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049 (China)

2010-05-10

36

Potentiometric studies at ORNL with hydrogen electrode concentration cells  

SciTech Connect

The absence of suitably stable reference electrodes for and to 300 C led ORNL to develop hydrogen electrode concentration cells for studies of equilibria of interest in reactor and steam generator systems to about 300 C during the late 1960`s and seventies. During the intervening two dozen years over twenty scientists have participated in potentiometric studies at Oak Ridge and much of that work will be summarized in this paper. A description of hydrogen electrode concentration cells developed in the late sixties and currently in use at Oak Ridge is given. The method of measurement, data interpretation, and published results are reviewed for studies of acid-base ionization, metal ion hydrolysis, and metal complexation reactions using principally such cells in titration or flow modes. 41 refs.

Mesmer, R.E.; Palmer, D.A.; Wesolowski, D.J. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

1994-12-31

37

First-principles study of III-V electrode interfaces for photoelectrochemical hydrogen production  

NASA Astrophysics Data System (ADS)

Photoelectrochemical (PEC) cells promise clean, sustainable production of hydrogen fuel using water and sunlight. However, combining solar conversion efficiency with durability in electrolyte solution has proven difficult, in part because the complex chemistry active at the electrode-electrolyte interface remains poorly understood. We use first-principles molecular dynamics simulations and model density-functional calculations to study the structure, stability, and chemical activity of GaP/InP semiconductor electrodes in contact with water. We find that a local bond-topological model is able to capture much of the basic surface chemistry. Interpretation of our results points to the particular importance of surface-adsorbed oxygen in determining the available reaction pathways for photocorrosion and water dissociation. Electronic signatures of the local bond topologies are compared to data from X-ray absorption and emission spectroscopy for insight into actual electrode structure.

Wood, Brandon; Ogitsu, Tadashi; Choi, Wooni; Schwegler, Eric

2012-02-01

38

Application of scanning tunneling microscopy to studies of electrode surfaces  

NASA Astrophysics Data System (ADS)

This project involved the study of a variety of different surfaces and structures in gaseous and liquid environments using the scanning tunneling microscope (STM) and other scanning probe microscopes with the aim of obtaining a better understanding of electrode surfaces and the processes occuring on these surfaces. With the STM we investigated chemical changes on the surface of electrodes, e.g., corrosion, passivation, and biochemical activities, and studied the energetics for electron transfer at the surfaces of semiconductors. We also investigated nanostructures (for example, very small semiconductor particles, porous Si, and self-assembled monolayers) using this technique.

Bard, Allen J.

1994-07-01

39

Quantitative study of non-covalent interactions at the electrode-electrolyte interface using cyanide-modified Pt(111) electrodes.  

SciTech Connect

Cations at the outer Helmholtz plane (OHP) can interact through non-covalent interactions with species at the inner Helmholtz plane (IHP), which are covalently bonded to the electrode surface, thereby affecting the structure and the properties of the electrochemical double layer. These non-covalent interactions can be studied quantitatively using cyanide-modified Pt(111) electrodes.

Escudero-Escribano, M.; Michoff, M. E. Z.; Leiva, E. P. M.; Markovic, N. M.; Gutierrez, C.; Cuesta, A. (Materials Science Division); (CSIC); (Universidad Nacional de Cordoba)

2011-08-22

40

Floating electrode dielectrophoresis.  

PubMed

In practice, dielectrophoresis (DEP) devices are based on micropatterned electrodes. When subjected to applied voltages, the electrodes generate nonuniform electric fields that are necessary for the DEP manipulation of particles. In this study, electrically floating electrodes are used in DEP devices. It is demonstrated that effective DEP forces can be achieved by using floating electrodes. Additionally, DEP forces generated by floating electrodes are different from DEP forces generated by excited electrodes. The floating electrodes' capabilities are explained theoretically by calculating the electric field gradients and demonstrated experimentally by using test-devices. The test-devices show that floating electrodes can be used to collect erythrocytes (red blood cells). DEP devices which contain many floating electrodes ought to have fewer connections to external signal sources. Therefore, the use of floating electrodes may considerably facilitate the fabrication and operation of DEP devices. It can also reduce device dimensions. However, the key point is that DEP devices can integrate excited electrodes fabricated by microtechnology processes and floating electrodes fabricated by nanotechnology processes. Such integration is expected to promote the use of DEP devices in the manipulation of nanoparticles. PMID:17117384

Golan, Saar; Elata, David; Orenstein, Meir; Dinnar, Uri

2006-12-01

41

An ellipsometric study of oxide film formation on zinc electrodes  

Microsoft Academic Search

A combination of experimental techniques to investigate and compare the growth kinetics, structure, composition and growth mechanism of oxide films on zinc electrodes prepared by anodizations in aqueous solutions of potassium hydroxide and in oxygen in the form of a glow discharge plasma. Electrical measurements and ellipsometry were used to monitor and study the oxide films as they were produced.

C. E. Mueller

1977-01-01

42

Solid Polymer Fuel Cells. Electrode and membrane performance studies.  

National Technical Information Service (NTIS)

This doctoral thesis studies aspects of fuel cell preparation and performance. The emphasis is placed on preparation and analysis of low platinum-loading solid polymer fuel cell (SPEC) electrodes. A test station was built and used to test cells within a w...

S. Moeller-Holst

1996-01-01

43

Theoretical study of trends in conductance for molecular junctions formed with armchair carbon nanotube electrodes  

NASA Astrophysics Data System (ADS)

The transmission through prototype aromatic molecule junctions formed between armchair (metallic) carbon nanotube electrodes is studied using a tight-binding model with a Green’s function embedding approach. Analytical and numerical results for transmission near the Fermi energy are obtained for junctions of single molecules with a one-point contact to each electrode, pairs of such molecules in the junction, and double stranded molecules with a two-point contact to each electrode. While an ideal single stranded molecule (ideal polyene) with odd number of atoms gives unit transmission at the Fermi energy, two such strands in the junction demonstrate significant interference effects, with net transmission varying from near zero to near 2 depending on the specific contact sites at the electrodes. Ideal polyenes with even number of atoms give nonresonant single-molecule transmission at the Fermi energy and less pronounced interference effects from their double-molecule junctions. The bonded, two stranded junction (polyacene) also gives nonresonant transmission at the Fermi energy. Allowing for the more realistic bond alternation observed in aromatic molecules results in nonresonant transmission with exponential length dependence.

Chen, Yiing-Rei; Zhang, Lei; Hybertsen, Mark S.

2007-09-01

44

Electrode, current collector, and electrolyte studies for AMTEC cells  

NASA Astrophysics Data System (ADS)

Studies of components for AMTEC devices at JPL have focussed on electrode materials, materials and construction of the current collection network, and the ?`-alumina solid electrolyte. Electrode materials include thin films of molybdenum metal and metal alloys such as PtW and RhW. Surface self-diffusion coefficients have been determined for Mo electrodes in the temperature range 1050-1200 K, and for RhW at 1125 K. The diffusion coefficients have been used in a grain growth model to predict electrode operating lifetimes at temperatures in this range. Current collection networks sputtered with a thin film of platinum have decreased total electrical resistance in an operating device by 35%. Electrolyte studies have found no mechanical stress or chemical degradation induced by long term operation. Further electrolyte studies have focussed on synthesis of both sodium and potassium ?`-alumina ceramic. Potassium ?`-alumina solid electrolyte has potential application in a potassium-based AMTEC device which operates at a hot side temperature of ~1000 K.

Ryan, Margaret A.; Williams, Roger M.; Underwood, Mark L.; Jeffries-Nakamura, Barbara; O'Connor, Dennis

1993-01-01

45

Theoretical modeling of RF ablation with internally cooled electrodes: comparative study of different thermal boundary conditions at the electrode-tissue interface.  

PubMed

Previous studies on computer modeling of RF ablation with cooled electrodes modeled the internal cooling circuit by setting surface temperature at the coolant temperature (i.e., Dirichlet condition, DC). Our objective was to compare the temperature profiles computed from different thermal boundary conditions at the electrode-tissue interface. We built an analytical one-dimensional model based on a spherical electrode. Four cases were considered: A) DC with uniform initial condition, B) DC with pre-cooling period, C) Boundary condition based on Newton's cooling law (NC) with uniform initial condition, and D) NC with a pre-cooling period. The results showed that for a long time (120 s), the profiles obtained with (Cases B and D) and without (Cases A and C) considering pre-cooling are very similar. However, for shorter times ( 30 s), Cases A and C overestimated the temperature at points away from the electrode-tissue interface. In the NC cases, this overestimation was more evident for higher values of the convective heat transfer coefficient (h). Finally, with NC, when h was increased the temperature profiles became more similar to those with DC. The results suggest that theoretical modeling of RF ablation with cooled electrodes should consider: 1) the modeling of a pre-cooling period, especially if one is interested in the thermal profiles registered at the beginning of RF application; and 2) NC rather than DC, especially for low flow in the internal circuit. PMID:19566131

Rivera, María J; Molina, Juan A López; Trujillo, Macarena; Berjano, Enrique J

2009-07-01

46

Studies of Low-Current Back-Discharge in Point-Plane Geometry with Dielectric Layer  

SciTech Connect

The paper presents results of spectroscopic investigations of back-discharges generated in the point-plane electrode geometry in ambient air at atmospheric pressure, with the plane electrode covered with a dielectric layer. Fly ash from an electrostatic precipitator of a coal-fired power plant was used as the dielectric layer in these investigations. The discharges for positive and negative polarities of the needle electrode were studied by measuring optical emission spectra at two regions of the discharge: near the needle electrode and dielectric layer surface. The visual forms of the discharge were recorded and correlated with the current-voltage characteristics and optical emission spectra. The back-arc discharge was of particular interest in these studies due to its detrimental effects it causes in electrostatic precipitators.

Jaworek, Anatol; Rajch, Eryk [Institute of Physics Pomeranian Pedagogical Academy, Arciszewskiego 22b, 76-200 Slupsk (Poland); Krupa, Andrzej; Czech, Tadeusz; Lackowski, Marcin [Institute of Fluid Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-952 Gdansk (Poland)

2006-01-15

47

External reflection studies of CO on platinized platinum electrodes  

SciTech Connect

Several studies have shown a difference in the electrochemical response of bare platinum vs platinized platinum electrodes. We have found that the thickness of the platinum black coverage on a Pt electrode also changes the spectroscopic response of CO adsorbed on such a surface. A polycrystalline electrode was platinized at 2.75 V in a solution of chloroplatinic acid/lead acetate for time periods of 10 to 30 s. External reflection spectra were calculated using a single-beam spectrum collected with a monolayer of CO on the electrode and a single beam spectrum without the adsorbed CO as a reference. At lower platinization times, the CO peak existed as the expected upward-going band. As the platinization time was increased, the band shape became dispersive and the intensity of the band increased. At the highest platinization time, the peak appeared to invert itself into a downward going band, i.e., the reflection increased in the region of the CO absorption. This surprising phenomenon appears to be directly related to the change in the surface features with increased platinization time.

Bjerke, Amy E.; Griffiths, Peter R. [Department of Chemistry, University of Idaho, Moscow, Idaho 83844-2343 (United States)

1998-06-01

48

Study on the interdiffusion in base-metal-electrode MLCCs  

Microsoft Academic Search

The co-firing techniques of base-metal-electrode (Ni) and dielectric oxides in reducing atmosphere were widely studied by many researchers. In this paper, the metal-oxide interface in BME-multilayer ceramic capacitors (MLCCs) have been investigated using AES, STEM, EDX, and HRTEM. It was found that the element inter-diffusion took place along the metal-dielectric layer interface and nickel element migration towards the dielectric ceramic

Z. L. Gui; Y. L. Wang; L. T. Li

2004-01-01

49

Study of nickel inner electrode lead-free piezoelectric ceramics  

Microsoft Academic Search

A (K,Na)NbO3 (KNN)-based multilayer piezoelectric ceramic with nickel inner electrodes was successfully fabricated by co-firing in a reducing atmosphere. We studied the compositional modification of KNN in order to increase reducing resistance in the sintering process, and obtained a good composition by using a solid solution with CaZrO3. A multilayer ceramic specimen had a ratio between the strain and induced

S. Kawada; M. Kimura; H. Hayashi; K. Ogiso; T. Konoike; H. Takagi

2011-01-01

50

Wire beam electrode: a new tool for studying localised corrosion and other heterogeneous electrochemical processes  

Microsoft Academic Search

Heterogeneous electrochemical processes are very common in industry and are important, but difficult topics in electrochemical and corrosion science studies. Traditional electrochemical techniques which employ a conventional one-piece electrode have major limitations in studying heterogeneous electrochemical processes since the one-piece electrode has major difficulties in measuring electrochemical parameters from local areas of the electrode surface. In order to overcome this

Yong-Jun Tan

1998-01-01

51

Studies on cloud point of agrochemical microemulsions  

Microsoft Academic Search

As part of our studies on green agrochemical formulations, four o\\/w agrochemical microemulsions have been prepared using five non-ionic surfactants with various hydrophilities and one co-surfactant. The effects of various formulation conditions, including surfactants, surfactant concentration, mixture of surfactant with various concentrations, pesticides in oil phase and water quality in the continuous medium on the cloud points of microemulsions have

Fuliang Chen; Yi Wang; Feineng Zheng; Yitian Wu; Wenping Liang

2000-01-01

52

Preliminary results from studies of limited streamer tubes with external electrode readout  

SciTech Connect

We report initial results from a new multichannel test facility built to study the properties of chambers constructed for the Warm Iron Calorimeter of the SLD detector as they are made. The correlation between the signal on the external electrodes and the wire is observed. A systematic study of the transition between the proportional and streamer modes of operation is given as a function of argonisobutane mixture and high voltage. The pulse height spectrum is correlated with the operational plateau of the chambers and may be used to determine optimum operating points under a variety of conditions.

Callegari, G.; DiCapua, E.; Piemontese, L.; Calcaterra, A.; de Sangro, R.; De Simone, P.; Peruzzi, I.; Piccolo, M.; Busza, W.; Cartwright, S.; Friedman, J.; Fuess, S.; Hansl-Kozanecka, T.; Kendall, H.; Lyons, T.; Osborne, L.; Rosenson, L.; Ross, D.; Schneekloth, U.; Taylor, F.; Verdier, R.; Williams, D.; Yamartino, J.; Bacchetta, N.; Bisello, D.; Castro, A.; Loreti, M.; Pescara, L.; Toniolo, D.; Wyss, J.; Alpat, B.; Artemi, C.; Battiston, R.; Bilei, G.M.; Cappelletti, C.; Dell'Orso, R.; Mantovani, G.; Pauluzzi, M.; Servoli, L.; Scarlatella, M.; Beconcini, F.; Castaldi, R.; Cazzola, U.; Vannini, C.; Verdini, P.G.; Messner, R.; Zdarko, R.; Johnson, J.R.

1987-10-01

53

Advanced PowerPoint Self Study  

NSDL National Science Digital Library

In order to recieve credit for the Advanced PowerPoint Night, you will need to complete *ALL* of the following activities. 1. Please search for of Advanced PowerPoint Features on Google. These examples demonstrate how PowerPoint can function in other ways besides a linear presentation. (Notice how button and hyperlinks are used to navigate through the slideshows.) 2. Read pages 1-8 in your Advanced PowerPoint Module . ...

Murphy, Rachel

2005-11-28

54

Study on the Realization of Indium Point  

NASA Astrophysics Data System (ADS)

Indium point cells are fabricated using ingots of various forms from a variety of sources (manufacturers). Using these cells, newly built indium point furnaces are evaluated and their reliability is confirmed. The indium point realizations based on the single solid-liquid method (SSL method) and multi solid-liquid method (MSL method) are evaluated. The effect of impurities in the ingots is evaluated from the dependency of the slope of the freezing curve on the change in furnace temperature, the indium point depression based on the impurity analysis, and the cell comparison. The results show equality among the cells. Based on the results obtained, the uncertainty in realizing the indium point using the described indium point cells and indium point furnaces is estimated. The new uncertainty budget introduces uncertainties coming from plateau repeatability and chemical impurity derived by the present work, the values of which are significantly lower than those adopted in the current calibration service.

Widiatmo, Januarius V.; Yamazawa, Kazuaki; Satou, Kouichi; Tamba, Jun; Arai, Masaru

55

In vitro study of iridium electrodes for neural stimulation.  

PubMed

Iridium is one of the main electrode materials for applications like neural stimulation. Iridium has a higher charge injection capacity when activated and transformed into AIROF (activated iridium oxide film) using specific electrical signals. Activation is not possible in stimulating devices, if they do not include the necessary circuitry for activation. We introduce a method for iridium electrode activation requiring minimum additional on-chip hardware. In the main part, the lifetime behavior of iridium electrodes is investigated. These results may be interesting for applications not including on-chip activation hardware, and also because activation has drawbacks such as worse mechanical properties and reproducibility of AIROF. PMID:23366018

Aryan, Naser Pour; Brendler, Christian; Rieger, Viola; Schleehauf, Sebastian; Heusel, Gerhard; Rothermel, Albrecht

2012-01-01

56

Some Studies into Electrical Discharge Machining of Nimonic75 Super Alloy Using Rotary Copper Disk Electrode  

NASA Astrophysics Data System (ADS)

The present study reports the rotary disk electrical discharge machining of Nimonic75 super alloy, extensively used in aerospace industries. The experiments have been performed using Taguchi's orthogonal array L18 (21 × 35) with copper disk electrode. The control factors considered were, viz., peak current, pulse on time, pulse off-time, gap voltage, and rotational speed of disk electrode with three levels each, and aspect ratio (AR) of the disk electrode having two levels, as noise factor. The novel approach of this article is to study the effect of the AR of the disk electrode on the performance measures, viz., material removal rate, disk electrode wear rate, and surface roughness. The results based on Taguchi's analysis show that among the considered process parameters, the AR and peak current significantly affect the machining characteristics. Furthermore, the rotating disk electrode easily flushes off the debris, resulting in better machining and reducing the chances of re-solidified layer formation.

Singh, S.; Pandey, A.

2013-05-01

57

Intraoperative study of polarization and evoked response signals in different endocardial electrode designs.  

PubMed

Some new generation pacemakers use an algorithm based on evoked response (ER) detection to verify beat-to-beat capture and to enable automatic adjustment of output. This is a prospective acute study of polarization signal (PS) and ER in nine currently available electrodes. Intraoperative testing of ventricular bipolar electrodes used the Autocapture (AC) algorithm. The intrinsic R wave, PS, ER, acceptance of AC function, and stimulation thresholds (STs) were obtained. Ventricular electrodes were categorized as follows: titanium nitride (TiN)-coated passive and active fixation, high impedance (HI), passive fixation (VP), iridium oxide-coated titanium (IROX) (VI), and platinum helix (PH) active fixation. Acute testing was performed in 217 patients with an average age of 74.26 years, 59.6% were men with primary pacing indication-SSS (46.3%). There were no significant differences found with respect to R wave and threshold between the various electrodes. PH active-fixation electrodes had significantly higher ER and PS than other groups including the TiN-coated active-fixation electrodes. TiN-coated electrodes (active and passive fixation) had significantly lower PS than other electrodes. As a result, TiN electrodes had a significantly higher functional rate of AC (91.7%), whereas PH had the lowest rate (0%). In conclusion, (1) polarization characteristics are significantly different for commercially available ventricular electrodes, (2) certain physical features at the tissue to electrode interface like TiN coating appears to be more important in determining PS than electrode tip size and fixation method, and (3) the current algorithm for AC requires electrodes that provide low polarization for satisfactory performance. PMID:11475819

Lau, C; Nishimura, S C; Yee, R; Lefeuvre, C; Philippon, F; Cameron, D A

2001-07-01

58

Lung Radiofrequency Ablation: In Vivo Experimental Study with Low-Perfusion-Rate Multitined Electrodes  

Microsoft Academic Search

The purpose of this study was to investigate the feasibility and safety of lung radiofrequency (RF) ablation by using low-perfusion-rate,\\u000a expandable, multitined electrodes in an in vivo animal model. Ten New Zealand White rabbits underwent RF ablation using low-perfusion-rate,\\u000a expandable, multitined electrodes (Starburst Talon; RITA Medical Systems, Mountain View, CA) and a 200-W RF generator. The\\u000a electrode was positioned under

Laura Crocetti; Riccardo Lencioni; Elena Bozzi; Alberto Sbrana; Carlo Bartolozzi

2008-01-01

59

Lung Radiofrequency Ablation: In Vivo Experimental Study with Low-Perfusion-Rate Multitined Electrodes  

Microsoft Academic Search

The purpose of this study was to investigate the feasibility and safety of lung radiofrequency (RF) ablation by using low-perfusion-rate, expandable, multitined electrodes in an in vivo animal model. Ten New Zealand White rabbits underwent RF ablation using low-perfusion-rate, expandable, multitined electrodes (Starburst Talon; RITA Medical Systems, Mountain View, CA) and a 200-W RF generator. The electrode was positioned under

Laura Crocetti; Riccardo Lencioni; Elena Bozzi; Alberto Sbrana; Carlo Bartolozzi

2008-01-01

60

Dedicated phantom to study susceptibility artifacts caused by depth electrode in magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

The susceptibility artifacts can degrade of magnetic resonance image quality. Electrodes are an important source of artifacts when performing brain imaging. A dedicated phantom was built using a depth electrode to study the susceptibility effects under different pulse sequences. T2-weighted images were acquired with both gradient-and spin-echo sequences. The spin-echo sequences can significantly attenuate the susceptibility artifacts allowing a straightforward visualization of the regions surrounding the electrode.

Garcia, J.; Hidalgo, S. S.; Solis, S. E.; Vazquez, D.; Nuñez, J.; Rodriguez, A. O.

2012-10-01

61

Study on the Time-Dependent Slow Response of the Tin Oxide pH Electrode  

Microsoft Academic Search

It has been known that drift and hysteresis resulted from the slow response of the pH electrodes. These inherent drawbacks handicap the application of the pH electrodes. Thus, the time-dependent slow response of the tin oxide pH electrode was modeled by mathematical expression. In this study, the three time-constant model was utilized to fit the drift behavior of the tin

Chu-Neng Tsai; Jung-Chuan Chou; Tai-Ping Sun; Shen-Kan Hsiung

2006-01-01

62

Radiometric and voltammetric study of benzoic acid adsorption on a polycrystalline silver electrode  

Microsoft Academic Search

Adsorption of benzoic acid was studied on polycrystalline silver electrodes in a 0.1M perchloric acid solution. The electrodes were obtained by electroplating of Ag-black onto a vacuum-deposited silver substrate. The real surface area of such prepared electrodes was calculated from a total capacitance of the electric double layer, determined from the plot of the voltammetric double-layer charging current as a

Piotr Waszczuk; Piotr Zelenay; Jerzy Sobkowski

1998-01-01

63

Comparative study of the characteristics of chloride-selective electrodes  

SciTech Connect

The authors evaluate a number of ion-selective electrodes from Soviet and foreign manufacturers for their sensitivity in the determination of chlorine ions and compounds in the presence of interfering iodine, bromine, phosphate, sulfate, and carbonate ions. The membrane electrodes are impregnated with silver chloride and silver sulfide and intended for use in the monitoring of waste water. Comparative data are presented also on properties such as electromotive force.

Radchenko, A.F.; Babeshko, G.I.; Chukov, S.P.

1987-11-10

64

Rotating disc electrode studies of borohydride oxidation at Pt and bimetallic Pt–Ni and Pt–Co electrodes  

Microsoft Academic Search

The electrochemical oxidation of borohydride has been studied by means of voltammetry at Pt and Pt–Ni, Pt–Co bimetallic rotating disc electrodes (RDEs). The bimetallic catalysts are prepared by means of a galvanic replacement method (whereby electrodeposited Ni and Co layers are partially replaced by Pt when immersed in a chloroplatinic solution) and are shown to have a Pt shell–bimetallic alloy

A. Tegou; S. Papadimitriou; I. Mintsouli; S. Armyanov; E. Valova; G. Kokkinidis; S. Sotiropoulos

2011-01-01

65

Study on the Realization of Zinc Point and the Zinc-Point Cell Comparison  

Microsoft Academic Search

Continuing our study on aluminum, tin, and silver points, a study on the realization of the zinc point was conducted. Zinc-point\\u000a cells were newly fabricated using 6N-nominal grade zinc samples, impurity elements of which were analyzed extensively based\\u000a on glow-discharge mass spectrometry (GDMS). The present paper reports the temperature measurements done using the newly fabricated\\u000a cells during the zinc freezing

J. V. Widiatmo; M. Sakai; K. Satou; K. Yamazawa; J. Tamba; M. Arai

2011-01-01

66

Redox behavior of the nickel oxide electrode system: quartz crystal microbalance studies  

Microsoft Academic Search

The electrochemical reactions occurring in the nickel oxide electrode system have been studied with the quartz crystal microbalance. Following cathodic deposition from nickel sulfate solutions, ?-nickel hydroxide films were cycled in 1.0M alkali metal hydroxide solutions. The oxidation process produced frequency decreases in these solutions, indicating a corresponding increase in mass in the electrode layer. Upon subsequent reduction, a return

Graham T. Cheek; William E. O'Grady

1997-01-01

67

Electrophysiology of focal clonic seizures in humans: a study using subdural and depth electrodes  

Microsoft Academic Search

Summary Focal clonic seizures are a frequent epileptic phenom- enon. However, there are few data about their patho- genesis. Eleven patients with focal epilepsy who experienced focal clonic seizures during prolonged video-EEG monitoring were included in this study. Nine patients had subdural electrodes on the precentral gyrus and one patient had additional bilateral subthala- mic nucleus (STN) depth electrodes. In

H. M. Hamer; H. O. Luders; S. Knake; B. Fritsch; W. H. Oertel; F. Rosenow

2003-01-01

68

Flash photoelectrochemical studies of transient electrode processes important in solar-energy conversion  

Microsoft Academic Search

Electroanalytical and spectroscopic measurement techniques were applied to the study of transient photolytic, photoemissive, and photoelectrolytic processes associated with UV-visible irradiation of an electrode\\/solution interface. Both semiconductor and metallic electrodes were employed. For the characterization of transient phenomena, the general methodology of flash photolysis was employed (including both xenon flash lamp and tunable pulsed dye laser sources). The perspective afforded

S. P. Perone

1982-01-01

69

Flash photoelectrochemical studies of transient electrode processes important in solar-energy conversion. Final report  

Microsoft Academic Search

It has been the objective of this research program to apply electroanalytical and spectroscopic measurement techniques to the study of transient photolytic, photoemissive, and photoelectrolytic processes associated with uv-visible irradiation of an electrode\\/solution interface. Both semiconductor and metallic electrodes have been employed. For the characterization of transient phenomena, the general methodology of flash photolysis was employed (including both xenon flash

Perone

1982-01-01

70

Experimental study of a short low-current vacuum arc on the electrodes of refractory metal  

Microsoft Academic Search

In this work the average current per cathode spot (CS) and the velocity of CS motion in a short low-current vacuum arc was investigated on electrodes of Molybdenum, subjected to a magnetic field. The study was performed on electrodes of 30 mm in diameter and 2mm gap at arc currents up to 300A. Two components of the external magnetic field

A. M. Chaly; V. S. Minaev; S. U. Myatovich; K. K. Zabello

2010-01-01

71

Studies of polyluminol modified electrode and its application in electrochemiluminescence analysis with flow system  

Microsoft Academic Search

In this work the electrochemical behavior of luminol in acidic solution is studied for the first time, and it is seen that luminol oxidized by electrochemistry can form the polymer on the surface of electrode, which is characterized by cyclic voltammetry (CV) and the surface enhanced Raman scattering (SERS) spectra. The mechanism of polymerization of luminol on electrode is also

Guo-Fang Zhang; Hong-Yuan Chen

2000-01-01

72

Abdominal wall trigger point case study.  

PubMed

Myofascial trigger points (TrPs) are posited to be an element in the etiology of both musculoskeletal and visceral pain. However, the recognition of TrPs as a causative factor in a patient's pain presentation varies amongst physicians and therapists. When myofascial pain syndrome is responsible for a patient's condition and is not recognized by the patient's medical advisors, the patient may be put through a plethora of testing procedures to find the cause of the patient's pain, and prescribed medications in an effort to treat the patient's symptoms. The case review presented here involves a patient with severe anterior abdominal pain, with a history of Crohn's disease, who experienced a long and difficult medical process before a diagnosis of myofascial pain syndrome was made. PMID:23561860

Muscolino, Joseph E

2013-01-03

73

Study of atmospheric pressure Capillary Plasma Electrode Discharge (CPED)  

Microsoft Academic Search

Atmospheric pressure plasmas, like dielectric barrier discharges (DBDs) or coronas, have long been used for a variety of industrial applications. Capillary Plasma Electrode Discharge (CPED) developed at Stevens Institute of Technology is a novel atmospheric pressure type discharge with a major potential for applications in surface cleaning, sterilization and VOC destruction. Capillary discharge is more stable, provides higher electron densities

Lukasz Moskwinski

2009-01-01

74

Mixed ionic and electronic conducting electrode studies for an alkali metal thermal to electric converter  

NASA Astrophysics Data System (ADS)

This research focuses on preparation, kinetics, and performance studies of mixed ionic and electronic conducting electrodes (MIEE) applied in an alkali metal thermal to electric converter (AMTEC). Two types of MIEE, metal/sodium titanate and metal/beta?-alumina were investigated, using Ni, Cu, Co and W as the metal components. Pure metal electrodes (PME) were also studied, including Ta, Ni, Nb, Ir, W and MoRe electrodes. The stability of MIEE/beta?-alumina solid electrolyte (BASE) interface was studied in terms of the chemical potential of Na-Al-Ti-O system at 1100K (typical AMTEC operating temperature). Ni metal was compatible with sodium titanate and BASE and displayed the best initial performance among all tested PMEs. Ni/sodium titanate electrodes with 4/1 mass ratios of metal/ceramic performed best among all tested electrodes. Scanning Electron Microscope (SEM) observations showed that grain agglomeration, which is the main mechanism for electrode degradation, occurred in all tested electrodes. Ceramic components were able to effectively limit the growth of metal grains and resulted in a long lifetime for MIEEs. Ni particles in the MIEE formed a network microstructure that was close to the theoretical morphology of the ideal electrode. A model based on percolation theory was constructed to interpret and predict the performance of MIEEs. The electrode kinetics was studied and a theoretical expression for the interface impedance was derived for both PME and MIEE, using electrochemical impedance spectroscopy (EIS). The conductivity of the Na2Ti 3O7 and Na2Ti6O13 mixture was measured. The average activation energy for the bulk conductivity was 0.87ev. Finally, theoretical analysis clarified that the transfer coefficient alpha value change would cause at most a few percent change in the electrode performance parameter B.

Guo, Yuyan

75

Studying the Performance of Conductive Polymer Films as Textile Electrodes for Electrical Bioimpedance Measurements  

NASA Astrophysics Data System (ADS)

With the goal of finding novel biocompatible materials suitable to replace silver in the manufacturing of textile electrodes for medical applications of electrical bioimpedance spectroscopy, three different polymeric materials have been investigated. Films have been prepared from different polymeric materials and custom bracelets have been confectioned with them. Tetrapolar total right side electrical bioimpedance spectroscopy (EBIS) measurements have been performed with polymer and with standard gel electrodes. The performance of the polymer films was compared against the performance of the gel electrodes. The results indicated that only the polypropylene 1380 could produce EBIS measurements but remarkably tainted with high frequency artefacts. The influence of the electrode mismatch, stray capacitances and large electrode polarization impedance are unclear and they need to be clarified with further studies. If sensorized garments could be made with such biocompatible polymeric materials the burden of considering textrodes class III devices could be avoided.

Cunico, F. J.; Marquez, J. C.; Hilke, H.; Skrifvars, M.; Seoane, F.

2013-04-01

76

Impedance study of tea with added taste compounds using conducting polymer and metal electrodes.  

PubMed

In this study the sensing capabilities of a combination of metals and conducting polymer sensing/working electrodes for tea liquor prepared by addition of different compounds using an impedance mode in frequency range 1 Hz-100 KHz at 0.1 V potential has been carried out. Classification of six different tea liquor samples made by dissolving various compounds (black tea liquor + raw milk from milkman), (black tea liquor + sweetened clove syrup), (black tea liquor + sweetened ginger syrup), (black tea liquor + sweetened cardamom syrup), (black tea liquor + sweet chocolate syrup) and (black tea liquor + vanilla flavoured milk without sugar) using six different working electrodes in a multi electrode setup has been studied using impedance and further its PCA has been carried out. Working electrodes of Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC) and conducting polymer electrodes of Polyaniline (PANI) and Polypyrrole (PPY) grown on an ITO surface potentiostatically have been deployed in a three electrode set up. The impedance response of these tea liquor samples using number of working electrodes shows a decrease in the real and imaginary impedance values presented on nyquist plots depending upon the nature of the electrode and amount of dissolved salts present in compounds added to tea liquor/solution. The different sensing surfaces allowed a high cross-selectivity in response to the same analyte. From Principal Component Analysis (PCA) plots it was possible to classify tea liquor in 3-4 classes using conducting polymer electrodes; however tea liquors were well separated from the PCA plots employing the impedance data of both conducting polymer and metal electrodes. PMID:23035436

Dhiman, Mopsy; Kapur, Pawan; Ganguli, Abhijit; Singla, Madan Lal

2012-09-01

77

The fabrication of low-impedance nanoporous gold multiple-electrode arrays for neural electrophysiology studies  

PubMed Central

Neural electrodes are essential tools for the study of the nervous system and related diseases. Low electrode impedance is a figure of merit for sensitive detection of neural electrical activity and numerous studies have aimed to reduce impedance. Unfortunately, most of these efforts have been tethered by a combination of poor functional coating adhesion, complicated fabrication techniques, and poor fabrication repeatability. We address these issues with a facile method for reliably producing multiple-electrode arrays with low impedance by patterning highly adherent nanoporous gold films using conventional microfabrication techniques. The high surface area-to-volume ratio of self-assembled nanoporous gold results in a more than 25-fold improvement in the electrode-electrolyte impedance, where at 1 kHz, 850 k? impedance for conventional Au electrodes is reduced to 30 k? for nanoporous gold electrodes. Low impedance provides a superior signal-to-noise ratio for detection of neural activity in noisy environments. We systematically studied the effect of film morphology on electrode impedance and successfully recorded field potentials from rat hippocampal slices. Here, we present our fabrication approach, the relationship between film morphology and impedance, and field potential recordings.

Seker, Erkin; Berdichevsky, Yevgeny; Begley, Matthew R; Reed, Michael L; Staley, Kevin J; Yarmush, Martin L

2011-01-01

78

Study of nickel hydroxide electrodes. 2: Oxidation products of nickel (2) hydroxides  

NASA Astrophysics Data System (ADS)

Pure phases of some oxidized Ni oxides were prepared galvanimetrically with the Ni(2) hydroxide electrode of an alkaline battery. The crystallographic data of these phases, their chemical behavior, and conditions of transition were studied.

Bode, H.; Demelt, K.; White, J.

1986-08-01

79

A Study in Enzyme Kinetics Using an Ion-Specific Electrode.  

ERIC Educational Resources Information Center

|Describes an undergraduate biochemistry laboratory experiment on enzyme kinetics using the D-amino acid oxidase system and an ammonia electrode. Preparation of an ammonia standard curve, a sample preparation, and inhibition studies are discussed. (YP)|

Turchi, Sandra; And Others

1989-01-01

80

Electrochemical noise study of the effect of electrode surface wetting on the evolution of electrolytic hydrogen bubbles  

Microsoft Academic Search

Ni and Ni–polytetrafluoroethylene (Ni–PTFE) composite electrodes were used as model systems for the study of the effect of electrode surface wetting on the evolution of electrolytic bubbles. This study was carried out by recording electrochemical noise and video images of the electrode surface. Ni–PTFE electrodes were prepared by a sediment co-deposition method, i.e., by electrodepositing Ni while PTFE particles, initially

H. Bouazaze; S. Cattarin; F. Huet; M. Musiani; R. P. Nogueira

2006-01-01

81

Study on the Realization of Zinc Point and the Zinc-Point Cell Comparison  

NASA Astrophysics Data System (ADS)

Continuing our study on aluminum, tin, and silver points, a study on the realization of the zinc point was conducted. Zinc-point cells were newly fabricated using 6N-nominal grade zinc samples, impurity elements of which were analyzed extensively based on glow-discharge mass spectrometry (GDMS). The present paper reports the temperature measurements done using the newly fabricated cells during the zinc freezing process, under which the zinc fixed point is defined, and the analysis of the freezing curve obtained. Comparisons of zinc-point temperatures realized by the newly fabricated cells (cell-to-cell comparisons) were also conducted. Zinc-point depression due to impurity elements was calculated based on the sum of individual estimates and the impurity element analysis. One of the cells evaluated was drawn out from its crucible and analyzed by GDMS at four points, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of the middle area. The purpose of this cell disassembly is to see whether or not there has been some difference before and after cell fabrication, as well as difference in impurity element distribution within the ingot. From the aforementioned studies, some findings were obtained. First finding is that the homogeneity of the zinc ingot was within 30%, except for Pb, which was more concentrated in the center part. Second finding is that the cell-to-cell temperature difference changes along with the progressing solidification process. As a consequence, for an accurate cell-to-cell comparison, the locus in the freezing plateau where the comparison is done should be determined. Third finding is that the slope analysis estimates accurately the cell-to-cell comparison, and is consistent with the impurity analysis. This shows that the slope analysis gives extensive information about the effect of impurity to the zinc-point realization, especially after the cell fabrication.

Widiatmo, J. V.; Sakai, M.; Satou, K.; Yamazawa, K.; Tamba, J.; Arai, M.

2010-11-01

82

Study on the Realization of Zinc Point and the Zinc-Point Cell Comparison  

NASA Astrophysics Data System (ADS)

Continuing our study on aluminum, tin, and silver points, a study on the realization of the zinc point was conducted. Zinc-point cells were newly fabricated using 6N-nominal grade zinc samples, impurity elements of which were analyzed extensively based on glow-discharge mass spectrometry (GDMS). The present paper reports the temperature measurements done using the newly fabricated cells during the zinc freezing process, under which the zinc fixed point is defined, and the analysis of the freezing curve obtained. Comparisons of zinc-point temperatures realized by the newly fabricated cells (cell-to-cell comparisons) were also conducted. Zinc-point depression due to impurity elements was calculated based on the sum of individual estimates and the impurity element analysis. One of the cells evaluated was drawn out from its crucible and analyzed by GDMS at four points, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of the middle area. The purpose of this cell disassembly is to see whether or not there has been some difference before and after cell fabrication, as well as difference in impurity element distribution within the ingot. From the aforementioned studies, some findings were obtained. First finding is that the homogeneity of the zinc ingot was within 30%, except for Pb, which was more concentrated in the center part. Second finding is that the cell-to-cell temperature difference changes along with the progressing solidification process. As a consequence, for an accurate cell-to-cell comparison, the locus in the freezing plateau where the comparison is done should be determined. Third finding is that the slope analysis estimates accurately the cell-to-cell comparison, and is consistent with the impurity analysis. This shows that the slope analysis gives extensive information about the effect of impurity to the zinc-point realization, especially after the cell fabrication.

Widiatmo, J. V.; Sakai, M.; Satou, K.; Yamazawa, K.; Tamba, J.; Arai, M.

2011-01-01

83

A finite-element study of the effects of electrode position on the measured impedance change in impedance cardiography  

Microsoft Academic Search

Traditional impedance cardiography (ICG) technique uses band electrodes both for delivering current to and measuring impedance change in the thorax. The use of spot electrodes increases the ease of electrode placement and comfort level for patients. Research has shown that changes in thoracic impedance can have multiple causes. In this study, we used finite element modeling to investigate the sources

Yanqun Wang; David R. Haynor; Yongmin Kim

2001-01-01

84

A study of electrical discharge grinding using a rotary disk electrode  

Microsoft Academic Search

This study aims to investigate the electrical discharge grinding (EDG) using a rotary disk electrode. From a practical perspective,\\u000a the electrode is designed to mimic the machining process of a surface grinder with horizontal spindles. First, the machining\\u000a ability of cold working tool steel AISI D2 by EDG is investigated. Then, the optimal machining parameters are found through\\u000a ANOVA analysis.

Hung Rung Shih; Kuen Ming Shu

2008-01-01

85

Electroanalytical study of sulfa drugs at diamond electrodes and their determination by HPLC with amperometric detection  

Microsoft Academic Search

Conductive boron-doped diamond thin film electrodes were examined for the electroanalysis of three sulfa drugs, sulfadiazine, sulfamerazine and sulfamethazine. Cyclic voltammetry, flow injection analysis and liquid chromatography with electrochemical detection were used to study the oxidation reactions. At diamond electrodes, highly reproducible and well-defined cyclic voltammograms were obtained for all three drugs with a signal to background (S\\/B) ratio of

Tata N Rao; B. V Sarada; D. A Tryk; A Fujishima

2000-01-01

86

MR Imaging-Related Heating of Deep Brain Stimulation Electrodes: In Vitro Study  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Recent work has shown a potential for excessive heating of deep brain stimulation electrodes during MR imaging. This in vitro study investigates the relationship between electrode heating and the specific absorption rate (SAR) of several MR images. METHODS: In vitro testing was performed by using a 1.5-T MR imaging system and a head transmit-receive coil, with bilateral

Daniel A. Finelli; Ali R. Rezai; Paul M. Ruggieri; Jean A. Tkach; John A. Nyenhuis; Greg Hrdlicka; Ashwini Sharan; Jorge Gonzalez-Martinez; Paul H. Stypulkowski; Frank G. Shellock

2002-01-01

87

Mass-transfer study of carbon felt, flow-through electrode  

NASA Astrophysics Data System (ADS)

The mass-transfer characteristics of a carbon felt, flow-through electrode that has potential application for the positive electrode in zinc-bromine batteries were studied. The electrochemical technique of limiting current measurements for the cathodic reduction of 0.0055-.062 M bromine in excess supporting electrolytes was used. In an electrochemical cell with perpendicular flow of electrolyte and current, limiting currents that were proportional to the electrolyte velocity, which was dependent on the electrode thickness but independent of the concentration of reactant species, were obtained at low Reynolds numbers. Analysis of the data using a model that relates the conversion efficiency of a porous electrode to a dimensionless group which contains experimental parameters such as porosity, pore diameter, flow rate, and diffusion coefficient, showed good agreement.

Kinoshita, K.; Leach, S. C.

1982-09-01

88

Experimental study and finite element analyses of electrode wear mechanisms during the resistance spot welding of galvannealed steel  

NASA Astrophysics Data System (ADS)

The wear mechanisms of electrodes used on resistance spot welding of galvannealed steels were studied. The study focused on the inter-relationship among the steel properties, welding parameters and electrode wear. Six different galvannealed steels were studied using a standard constant current welding test. With the same kind of Cu-Zr electrode, the tests were performed with the electrode force fixed at 600 lbs and the welding time fixed at 12 cycles for all the steels studied. The welding current is set at just below the expulsion limit for each of the steels. The microstructure and mechanical properties of these steels were examined by SEM and microhardness tests. The face profiles for electrodes subjected to various numbers of welds were examined using carbon imprint tests and low magnification optical microscopy. The alloys formed on the electrode face were studied by the EDS and WDS quantitative analyses and linescans. Changes in the microhardness of the electrode material near the electrode face during the electrode wear process were also studied. Combined with the experimental examination, a sequentially coupled finite element analysis procedure was used to analyze the detailed distribution and evolution of the electrical current, temperature and stress throughout the process of making a weld. These analyses have greatly enhanced the understanding of the experimental observations. The results of this study indicate that the welding current is the dominant factor influencing electrode life. When the electrode force and the welding time are fixed, the welding current is determined by the steel properties. Thicker steel sheets and higher steel sheet surface hardnesses will result in smaller welding current. When the electrode force and welding time are fixed, steels requiring higher welding currents will yield shorter electrode lives. With increasing welding current, the top and bottom electrodes in this study showed increasingly different wear behaviors. Electrodes used on steels requiring higher welding current developed an edge pit near the top electrode periphery, that gradually evolved into a large pit at the bottom electrode face center. Toward the end of the electrode life, these electrodes result in a "three spots" feature nuggets that are shifted toward the top electrode. This kind of electrode failure is characterized by "nugget shifting". In contrast, under smaller welding current, the top and bottom electrode wear approximately the same. As the electrode face diameter increases gradually, not all the face area is in good contact with the steel sheet during welding. The localized contact areas for the top and bottom electrodes are symmetric and become fragmented gradually toward the end of the electrode life. The fragmentation of the electrode face areas which can be in good contact with the steel sheet results in the shunting of the welding current. When the electrical current density is reduced to a certain level by the shunting effect, the nugget can not be formed and the electrodes are declared to be failed. This kind of electrode failure is characterized by nugget shrinking. The welding current also has a big influence on the other electrode wear mechanism as the electrode mushrooming, face alloying, etc.

Lu, Feng

89

Improvement of the interface integrity between a high-k dielectric film and a metal gate electrode by controlling point defects and residual stress  

Microsoft Academic Search

In this study, the influence of composition of thin films on the interface integrity between a hafnium dioxide thin film and a gate electrode was investigated by using a quantum chemical molecular dynamics method. Effect of the fluctuation of the composition around the HfO2±x\\/metal interface on the formation of the interfacial layer was analyzed quantitatively. Post-oxidation annealing after deposition of

Ken Suzuki; Tatsuya Inoue; Hideo Miura

2010-01-01

90

Reference electrode assembly and its use in the study of fluorohydrogenate ionic liquid silicon electrochemistry.  

PubMed

Silicon electrochemistry in fluorohydrogenate ionic liquids is partly hampered owing to the incapability of producing an accurate and reproducible potential measurement due to a lack of appropriate reference electrodes. This research work describes a simple assembly of a stable external reference electrode enabling accurate studies of silicon electrochemistry in fluorohydrogenate ionic liquids. The electrode configuration is based on the ferrocene/ferrocenium (Fc|Fc(+)) couple dissolved in the EMIm(HF)2.3F (1-ethyl-3-methyl-imidazolium fluorohydrogenate)/Carbopol 941 gel. A stable potential of 2.5 wt% Carbopol-based electrode was measured versus a calomel reference electrode at 250 ± 3 mV. By utilizing the constructed electrode, an intensive electrochemical investigation on n-type silicon in EMIm(HF)2.3F was conducted. Flat-band and open circuit potentials were measured, along with Si-air half- and full-cell electrochemical measurements. A suggested mechanism for the n-type Si dissolution process in the EMIm(HF)2.3F electrolyte, without illumination, is discussed as well. PMID:24045638

Shvartsev, Boris; Cohn, Gil; Shasha, Hila; Eichel, Rüdiger-A; Ein-Eli, Yair

2013-10-01

91

Origins of the Human Pointing Gesture: A Training Study  

ERIC Educational Resources Information Center

|Despite its importance in the development of children's skills of social cognition and communication, very little is known about the ontogenetic origins of the pointing gesture. We report a training study in which mothers gave children one month of extra daily experience with pointing as compared with a control group who had extra experience with…

Matthews, Danielle; Behne, Tanya; Lieven, Elena; Tomasello, Michael

2012-01-01

92

Dithiooxamide Modified Glassy Carbon Electrode for the Studies of Non-Aqueous Media: Electrochemical Behaviors of Quercetin on the Electrode Surface  

PubMed Central

Electrochemical oxidation of quercetin, as an important biological molecule, has been studied in non-aqueous media using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. To investigate the electrochemical properties of quercetin, an important flavonoid derivative, on a different surface, a new glassy carbon electrode has been developed using dithiooxamide as modifier in non-aqueous media. The surface modification of glassy carbon electrode has been performed within the 0.0 mV and +800 mV potential range with 20 cycles using 1 mM dithioxamide solution in acetonitrile. However, the modification of quercetin to both bare glassy carbon and dithiooxamide modified glassy carbon electrode surface was carried out in a wide +300 mV and +2,800 mV potential range with 10 cycles. Following the modification process, cyclic voltammetry has been used for the surface characterization in aqueous and non-aqueous media whereas electrochemical impedance spectroscopy has been used in aqueous media. Scanning electron microscopy has also been used to support the surface analysis. The obtained data from the characterization and modification studies of dithioxamide modified and quercetin grafted glassy carbon electrode showed that the developed electrode can be used for the quantitative determination of quercetin and antioxidant capacity determination as a chemical sensor electrode.

Mulaz?moglu, Aysen Demir; Y?lmaz, Ecir; Mulaz?moglu, Ibrahim Ender

2012-01-01

93

Point and non-point microbial source pollution: A case study of Delhi  

NASA Astrophysics Data System (ADS)

The present study identifies major point and non-point sources of microbial pollution during dry and wet weather in Delhi watershed which is the first prerequisite for planning and management of water quality of the river Yamuna. Fecal coliforms (FC) and fecal streptococci (FS) levels were determined from two types of sources - point source (effluent from sewage treatment plants) and non-point source (stormwater runoff during dry and wet weather). FC and FS levels in the river Yamuna were also monitored, which is an ultimate sink for all microbial loads in Delhi watershed. Effluent from sewage treatment plants (STPs) employing different treatment technologies were evaluated. FC and FS levels greater than the effluent discharge standard (1000 MPN/100 ml) were observed in the effluents from all STPs except "oxidation pond Timarpur". This study also involved field program for characterization of urban runoff from different land-uses. Results indicated that the microbial quality of urban runoff produced during wet weather from different land-uses was similar to that of raw sewage. Sewage overflows along with human and animal sources were responsible for high FC and FS levels in the runoff samples. Wet weather FC and FS levels in river Yamuna were higher as compared to the dry weather levels suggesting that dilution of the river water during wet weather does not affect its microbiological quality. Thus on the basis of this study it was found that urban runoff also contributes to the microbial quality of the river Yamuna.

Jamwal, Priyanka; Mittal, Atul K.; Mouchel, Jean-Marie

94

Review and Evaluation of the Indian Point Probabilistic Safety Study.  

National Technical Information Service (NTIS)

This report summarizes the review of the internal and external event portions of the Indian Point Probabilistic Safety Study (IPPSS). The review was conducted by Sandia National Laboratories and Sandia contractors over approximately a 6-month period. The ...

A. M. Kolaczkowski D. L. Berry G. J. Kolb J. W. Hickman R. G. Easterling

1982-01-01

95

An IPE back-end study for Turkey Point plant  

SciTech Connect

This paper describes a study of Turkey Point plant's large dry containment as part of a response to the US Nuclear Regulatory Commission's individual plant examination Generic Letter 88-20. Two unique features of Turkey Point containment are discussed. This study includes an evaluation of the containment response to the physical processes occurring during an accident and probabilistic analysis of the spectrum of severe-accident progressions.

Guey, C.; Kabadi, J. (Florida Power and Light Co., Juno Beach (United States))

1991-01-01

96

Electrode polarization studies in hot corrosion systems. Progress report, 1 June 1981-31 May 1982  

Microsoft Academic Search

The work under this contract will be unclassified and will consist of polarization experiments on metals and alloys in sulfur-bearing molten salts under reducing atmospheres and gas\\/metal reaction studies in sulfur-bearing reducing gases. Kinetic studies and metallographic analyses will be performed in each area. Electrode polarization studies include the materials of sodium carbonate and sodium sulfide.

Devereux

1982-01-01

97

Improved separability of dipole sources by tripolar versus conventional disk electrodes: a modeling study using independent component analysis.  

PubMed

Tripolar electrodes have been shown to have less mutual information and higher spatial resolution than disc electrodes. In this work, a four-layer anisotropic concentric spherical head computer model was programmed, then four configurations of time-varying dipole signals were used to generate the scalp surface signals that would be obtained with tripolar and disc electrodes, and four important EEG artifacts were tested: eye blinking, cheek movements, jaw movements, and talking. Finally, a fast fixed-point algorithm was used for signal independent component analysis (ICA). The results show that signals from tripolar electrodes generated better ICA separation results than from disc electrodes for EEG signals with these four types of artifacts. PMID:19964335

Cao, H; Besio, W; Jones, S; Medvedev, A

2009-01-01

98

Electrochemical measurements for marine atmospheric corrosion studies using Kelvin probe reference electrode  

NASA Astrophysics Data System (ADS)

A Kelvin probe was used as reference in this study on electrochemical measurements of a simulated marine atmospheric corrosion system (electrode covered by a very thin electrolyte layer). The experimental setups for improved measurements proved satisfactory for the conventional steady—state electrochemical measurements in atmospheric studies.

Wang, Jia

1996-09-01

99

Kinetic study of slaughterhouse wastewater treatment by electrocoagulation using Fe electrodes.  

PubMed

In this study, treatment of slaughterhouse wastewater by electrocoagulation was investigated in batch system using Fe electrodes. The effect of various variables such as electrode number, current density and operating time was tested. Pollutant removal efficiency increased with increasing electrode number and operating time. The biochemical oxygen demand (BOD(5))(,) chemical oxygen demand (COD), total suspended solid (TSS), and total nitrogen (TN) removal efficiencies using eight electrodes at a contact time of 50 min and a current density of 10 A/m(2) were 66, 62, 60, and 56%, respectively. Higher electrode numbers will allow shorter operating times to achieve certain removal efficiencies. Also, removal efficiencies increased by increasing the current density; the highest removal efficiencies of BOD(5,) COD, TSS, and TN at a contact time of 50 min and a current density of 25 A/m(2) were 97, 93, 81, and 84%, respectively. The results also show that the reactor pH varies directly with the current density; at 25 A/m(2), the reactor pH increased from an initial value of 7.1 to 7.7 after 50 min. The experimental results showed that the kinetics of BOD(5), COD, TSS and TN removal could be fitted adequately using a first order kinetic model (higher R(2)). PMID:22766863

Ahmadian, Mohammad; Yousefi, Nader; Van Ginkel, Steven W; Zare, Mohammad Reza; Rahimi, Sajad; Fatehizadeh, Ali

2012-01-01

100

Fabrication of amperometric electrodes.  

PubMed

Carbon fiber electrodes are crucial for the detection of catecholamine release from vesicles in single cells for amperometry measurements. Here, we describe the techniques needed to generate low noise (<0.5 pA) electrodes. The techniques have been modified from published descriptions by previous researchers (1,2). Electrodes are made by preparing carbon fibers and threading them individually into each capillary tube by using a vacuum with a filter to aspirate the fiber. Next, the capillary tube with fiber is pulled by an electrode puller, creating two halves, each with a fine-pointed tip. The electrodes are dipped in hot, liquid epoxy mixed with hardener to create an epoxy-glass seal. Lastly, the electrodes are placed in an oven to cure the epoxy. Careful handling of the electrodes is critical to ensure that they are made consistently and without damage. This protocol shows how to fabricate and cut amperometric electrodes for recording from single cells. PMID:19415069

Pike, Carolyn M; Grabner, Chad P; Harkins, Amy B

2009-05-04

101

Two and Three-Electrode Impedance Studies on 18650 Li-Ion Cells  

SciTech Connect

Two and three electrode impedance measurements were made on 18650 Li-ion cells at different QB temperatures ranging from 35 C to {minus}40 C. The ohmic resistance of the cell is nearly constant the temperature range studied although the total cell impedance increases by an order of magnitude in the same temperature range. In contrast to what is commonly believed, we show from our three-electrode impedance results that, the increase in cell impedance comes mostly from the cathode and not from the anode. Further, the anode and cathode contribute to both the impedance loops (in the NyQuist plot).

Nagasubramanian, Ganesan

1999-08-11

102

Insertion of lithium into mesoscopic anatase electrodes – an electrochemical and in-situ EQCM study  

Microsoft Academic Search

The insertion of Li+ into mesoscopic TiO2 (anatase) electrodes was studied using cyclic voltammetry combined with the in situ gravimetric monitoring of the electrode\\u000a mass in LiClO4 and Li(CF3SO2)2 N\\/propylene carbonate (PC)-based solutions. The insertion of Li+ takes place at potentials less than 2.0?V vs Li\\/Li+. The cathodic process is associated with a mass uptake; the subsequent oxidation process is

Petr Krtil; Ladislav Kavan; Dina Fattakhova

1997-01-01

103

Kinetic Studies of the Electrolytic Reduction of Carbon Dioxide on the Mercury Electrode.  

National Technical Information Service (NTIS)

The reduction of CO2 to HCOOH was studied for the Hg electrode in neutral and acidic aqueous solutions in the potential range between -0.8 and -1.9 V(sce). In the neutral pH range all the current is consumed in the production of formic acid, while in acid...

W. Paik T. N. Andersen H. Eyring

1968-01-01

104

A study of Faradaic phenomena in activated carbon by means of macroelectrodes and single particle electrodes  

Microsoft Academic Search

The electrochemical behaviour of a chemically activated carbon with oxygen-containing surface groups was studied using a conventional macroelectrode configuration with disc electrodes and the single particle microelectrode technique. The results of both experimental set-ups were compare taking into account the visible peaks of the surface groups, capacitance and Faradaic currents. Galvanostatic cycling and cyclic voltammetry performed at different potential windows

V. Ruiz; H. Malmberg; C. Blanco; A. Lundblad; P. Björnbom; R. Santamaría

2008-01-01

105

New tined lead electrode in sacral neuromodulation: experience from a multicentre European study  

Microsoft Academic Search

The use of a new tined lead electrode for sacral neuromodulation (SNS) was evaluated in a European study including 127 patients with chronic voiding dysfunction. The tined lead can be implanted during the first stage of the SNS procedure, which makes a longer test period possible before implanting the pulse generator in a second stage. Implantation of the tined lead

Michele Spinelli; Ernest Weil; Edoardo Ostardo; Giulio Del Popolo; José L. Ruiz-Cerdá; Gustav Kiss; John Heesakkers

2005-01-01

106

A study on electrode for amperometric measurement of human stress with flow injection analysis biosensing system  

Microsoft Academic Search

This paper presents a study on electrode for the amperometric detection of human stress based on salivary alpha amylase, emulated with different concentration of glucose, with the flow injection analysis biosensing system. Amperometric detection is an electrochemical voltammetric measurement approach, where the current intensity in a detection cell is regarded as a function of the concentration of the analyte. Flow

Lee Yoot Khuan; M. Hurairah Adha b Kamaruddin; Mohd Firdaus Abdullah; N. K. Madzhi; Anuar Ahmad

2010-01-01

107

A Pilot Study of Robot-Assisted Cochlear Implant Surgery Using Steerable Electrode Arrays  

Microsoft Academic Search

This paper presents results of a pilot study evaluating the efficacy of robotic assistance using novel steerable electrode arrays for cochlear implant surgery. The current surgical setup of cochlear implant surgery is briefly re- viewed and its limitations are highlighted. In an effort to reduce trauma to the structure of the cochlea, the kinematics and path planning for novel cochlear

Jian Zhang; Kai Xu; Nabil Simaan; Spiros Manolidis

2006-01-01

108

Electrode/Electrolyte Interphase Study Using Polarization Modulated FT-IR Reflection Absorption Spectroscopy.  

National Technical Information Service (NTIS)

The polarization modulated Fourier transform infrared reflection-absorption spectroscopy (FT-IRRAS) is applied to the studies of adsorption and oxidation of Carbon monoxide (CO) on a platinum electrode in 0.5M sulfuric acid and of adsorption of cyanide on...

K. Kunimatsu H. Seki W. G. Golden J. G. Gordon M. R. Philpott

1986-01-01

109

Electrode polarization studies in hot corrosion systems. Progress report, 1 July 1978--31 May 1979  

Microsoft Academic Search

Work is reported on thermodynamic analysis of gasifier models, equilibrium calculations performed on two and thre phase equilibrium involving components of coal gas, sodium salts, and carbon. Electrode polarization studies in molten sodium carbonate and polarization tests were performed on iron, steel, nickel, and on 304 and 316 stainless steel in molten sodium carbonate under a variety of exploratory environments.

Devereux

1979-01-01

110

Optimum design of substation grounding in a two layer earth structure part: III?Study of grounding grids performance and new electrodes configuration  

Microsoft Academic Search

In a previous paper [1] the authors have presented the theoretical basis of their computer program which determines grounding electrodes performance. In this last paper of the series presented, a detailed study of the influence of electrodes and earth parameters on grounding performance is analysed for different types of practical electrodes. A brief analysis and discussion of new electrodes configuration

F. Dawalibi; D. Mukhedkar

1975-01-01

111

Novel corrosion experiments using the wire beam electrode. (I) Studying electrochemical noise signatures from localised corrosion processes  

Microsoft Academic Search

This series of papers presents four novel experiments that were designed to study localised corrosion phenomena using an electrochemically integrated multi-electrode array namely the wire beam electrode (WBE). This present paper reports a WBE based experimental method that has been employed, for the first time, to study electrochemical noise patterns (called noise signatures) from localised corrosion processes. The objective of

Yong-Jun Tan; Naing Naing Aung; Tie Liu

2006-01-01

112

An Electroencephalographic Study of Flying Personnel Utilizing Nasopharyngeal Electrodes.  

National Technical Information Service (NTIS)

The results of the first 51 consecutive nasopharyngeal electroencephalograms done at the USAF School of Aerospace Medicine are presented. Nine studies were done on healthy advanced pilot program evaluees. Of 14 cases felt to have psychomotor seizures on p...

L. F. Romain

1969-01-01

113

Design point studies for future spherical torus devices  

SciTech Connect

A Systems Code analysis has been developed which provides a tool for the assessment of design points for future spherical torus (ST) devices. The code includes algorithms for plasma physics as well as engineering aspects, which are necessarily simplified but sufficient to capture the essential design-driving considerations. This paper describes the methodology and presents some example cases from ongoing studies.

Neumeyer, C. L. [Princeton Plasma Physics Laboratory (PPPL); Peng, Yueng Kay Martin [ORNL; Rutherford, P. H. [Princeton Plasma Physics Laboratory (PPPL)

2003-01-01

114

Point Contact Andreev Reflection Studies on Iron Pnictide Superconductors  

Microsoft Academic Search

We have systematically investigated the temperature, doping and the directional dependence of the gap structure for various types of single crystal iron pnictide superconductors by point contact Andreev reflection spectroscopy. Our studies were performed on highly transparent junctions evidenced by sharp and dramatic conductance enhancements at low temperatures. For the 122 family, despite some small features occasionally observed on the

Xiaohang Zhang; S. R. Saha; N. P. Butch; K. Kirshenbaum; J. Paglione; R. L. Greene; I. Takeuchi; Y.-S. Oh; Y. Liu; L. Q. Yan; K.-H. Kim

2011-01-01

115

Summary of the Zion\\/Indian Point study  

Microsoft Academic Search

Results of a study for the identification of reactor core-melt accident mitigation measures at the Zion and Indian Point plants are summarized. Mitigation strategies have been identified that show promise of providing large reductions in consequences for specific accident sequences. However, without an overall risk analysis, it is not clear to what extent a given mitigation scheme reduces overall risk.

Murfin

1980-01-01

116

Epidemiological study of fixed drug eruption in Pointe-Noire.  

PubMed

A prospective study was conducted over a 27 month period in order to determine the epidemiological profile of fixed drug eruption (FDE) observed during a dermatological consultation at Pointe-Noire. During the study period 54 out of 9,070 persons consulting (0.6%) suffered from clinically diagnosed FDE. The variables studied were: age, sex, medicine and point of sale. The average age of onset was 30 years. The frequency of onset was higher in males (38 patients) than in females (16 patients). The incriminated medicines were: the sulfamides (48 patients) including Cotrimoxazole (45 patients ) and Sulfadoxine and Pyremethamine (3 patients) Coartem(®) + Doliprane(®) (1 patient), Chloramphenicol(®) (1 patient), Amidol(®) (1 patient), Duocotexin(®) + Paracetamol(®) (1 patient), Surquina(®) (1 patient), Amodiaquine(®) (1 patient). The point of sale was illicit (peddlers, markets) for 44 patients; for 10 patients it was a lawful outlet (pharmacies). This study shows that cotrimoxazole bought at illicit points of sale is the main etiology of FDE in the department, confirming that these medicines are counterfeit. The involvement of dermatologists in the fight against the illicit sale of medicines should be made a priority. PMID:23210952

Ognongo-Ibiaho, A N; Atanda, H L

2012-11-01

117

Insertion of electrode array using percutaneous cochlear implantation technique: a cadaveric study  

NASA Astrophysics Data System (ADS)

Cochlear implantation is a surgical procedure for treating patients with hearing loss in which an electrode array is inserted into the cochlea. The traditional surgical approach requires drilling away a large portion of the bone behind the ear to provide anatomical reference and access to the cochlea. A minimally-invasive technique, called percutaneous cochlear implantation (PCI), has been proposed that involves drilling a linear path from the lateral skull to the cochlea avoiding vital structures and inserting the implant using that drilled path. The steps required to achieve PCI safely include: placing three bone-implanted markers surrounding the ear, obtaining a CT scan, planning a surgical path to the cochlea avoiding vital anatomy, designing and constructing a microstereotactic frame that mounts on the markers and constrains the drill to the planned path, affixing the frame on the markers, using it to drill to the cochlea, and inserting the electrode through the drilled path. We present in this paper a cadaveric study demonstrating the PCI technique on three temporal bone cadaveric specimens for inserting electrode array into the cochlea. A custom fixture, called a Microtable, which is a type of microstereotactic frame that can be constructed in less than five minutes, was fabricated for each specimen and used to reach the cochlea. The insertion was successfully performed on all three specimens. Postinsertion CT scans confirm the correct placement of the electrodes inside the cochlea without any damage to the facial nerve.

Balachandran, Ramya; Mitchell, Jason E.; Noble, Jack; Schurzig, Daniel; Blachon, Grégoire; McRackan, Theodore R.; Webster, Robert J.; Dawant, Benoit M.; Fitzpatrick, J. Michael; Labadie, Robert F.

2011-03-01

118

Generalized Lagrangian Points: Studies of Resonance for Highly Eccentric Orbits  

NASA Astrophysics Data System (ADS)

A number of dynamically interesting aspects of the solar system---including, for example, the scattered Kuiper Belt objects and the creation of the Oort cloud---involve small bodies on eccentric orbits which are perturbed by a dominant major planet. Due to the sizeable eccentricities involved, these situations are hard to study using the usual eccentricity expansion of the disturbing function applied to the restricted circular three-body problem. As an alternate approach, we develop a framework based on energy kicks for the evolution of high-eccentricity long-period orbits in the restricted circular planar three-body problem with Jacobi constant close to 3 and with secondary to primary mass ratio ? << 1. We use this framework to explore mean-motion resonances between the test particle and the massive bodies. This approach leads to a redefinition of resonance orders for the high-eccentricity regime in which a p:p+q resonance is called `pth order' instead of the usual `qth order' to reflect the importance of interactions at periapse. This approach also produces a pendulum-like equation describing the librations of resonance orbits about fixed points which correspond to periodic trajectories in the rotating frame. A striking analogy exists between these new fixed points and the Lagrangian points as well as between librations around the fixed points and the well-known tadpole and horseshoe orbits; we call the new fixed points the `generalized Lagrangian points'. Finally, our approach gives a condition a ˜ ? -2/5 for the onset of chaos at large semimajor axis a; a range ? < ˜ 5x 10-6 in secondary mass for which a test particle initially close to the secondary cannot escape from the system, at least in the planar problem; and a simple explanation for the presence of asymmetric librations in exterior 1:N resonances and the absence of these librations in other exterior resonances.

Pan, M.; Sari, R.

2003-05-01

119

Electrochemical studies of an unsupported PtIr electrocatalyst as a bifunctional oxygen electrode in a unitized regenerative fuel cell  

Microsoft Academic Search

The electrochemical performance of an unsupported PtIr electrocatalyst was evaluated as a bifunctional oxygen electrode in a unitized regenerative fuel cell (URFC). The catalyst was a mixture of unsupported Pt black and Ir black catalysts in varying proportions. The performance of the unsupported PtIr catalyst was studied by using a rotating ring disc electrode (RRDE) and linear sweep voltammetry (LSV).

Ho-Young Jung; Branko N. Popov

2009-01-01

120

Electrochemical studies on the performance of SS316L electrode in electrokinetics  

Microsoft Academic Search

Organic and trace metal pollutants are removed by employing various electrodes in an electrokinetic (EK) process. Stainless\\u000a steel was used either as an anode or a cathode by various investigators in electroremediation systems. In the present study,\\u000a the role of SS316L as an anode and cathode in EK system was studied by the measurements of pH, conductivity of electrolyte,\\u000a and

Jeong-Hee Choi; Sundaram Maruthamuthu; Hyun-Goo Lee; Tae-Hyun Ha; Jeong-Hyo Bae

2009-01-01

121

Part I: A comparative study of bismuth-modified screen-printed electrodes for lead detection.  

PubMed

Lead determination was carried out in the frame of the European Union project Biocop (www.biocop.org) using a bismuth-modified screen-printed electrode (Bi-SPE) and the stripping analysis technique. In order to choose a sensitive Bi-SPE for lead detection, an analytical comparative study of electrodes modified by Bi using "in situ", "ex situ" and "bulk" procedures was carried out. On the basis of the results obtained, we confirmed that the "in situ" procedure resulted in better analytical performances with respect to not only "ex situ" but also to "Bi(2)O(3) bulk" modified electrodes, allowing for a linear range of lead ion concentration from 0.5 to 100 ?g L(-1) and a detection limit of 0.15 ?g L(-1). We demonstrated that, before the Bi film deposition, an oxidative electrochemical pre-treatment of the working electrode could be useful because it eliminates traces of lead in the graphite-ink, as shown with stripping measurements. It also improves the electrochemical performance of the electrodes as demonstrated with Electrochemical Impedance Spectroscopy (EIS) measurements. The influence of different analytical parameters, such as the electrolyte solution composition (acetate buffer, chloridric acid, nitric acid, perchloric acid) and the ionic strength was investigated in order to evaluate how to treat the sample before the analysis. The morphology of prepared "in situ" Bi-SPEs was also characterized by Atomic Force Microscopy (AFM). Finally, the Bi-SPEs were used to determine the concentration of lead ions in tap and commercial water samples obtaining satisfactory values of the recovery percentage (81% and 98%). PMID:22027135

Quintana, Josefina Calvo; Arduini, Fabiana; Amine, Aziz; Punzo, Francesco; Destri, Giovanni Li; Bianchini, Chiara; Zane, Daniela; Curulli, Antonella; Palleschi, Giuseppe; Moscone, Danila

2011-09-16

122

Nickel Hydroxide Electrode Research.  

National Technical Information Service (NTIS)

The report discusses results of work performed to develop an improved nickel hydroxide electrode for use in rechargable alkaline electrodes for aerospace applications. Voltametric cycling studies have shown that all deliberate additions of cations (cobalt...

H. A. Christopher J. L. Weininger J. G. Ruzzo R. F. Thornton P. J. Moran

1970-01-01

123

Impact of point-source injection methodologies on injection studies  

NASA Astrophysics Data System (ADS)

Effective interdiction of illicit radioactive material requires decision criteria that are sensitive to the material of interest, while insensitive to material of lesser interest. Injection studies are used to assess the sensitivities of decision criteria to radioactive threat scenarios. Configuring injection studies requires decisions about methodological factors that represent or simplify actual field conditions. Understanding the relative impact of different source injection methods on alarm rates and other outcome measures is vital for interpreting results of injection studies. The most complete and realistic way to inject point-source counts into a vehicle count profile is with the randomly positioned source profile approach. In this paper, we report a study of the impacts of methodological simplifications to this approach. We assessed relative sensitivity of two field-deployed detection algorithms to two experimental factors in point-source injection studies. The first factor featured “centered” versus “random” point-source position along the vehicle count profile. The second factor featured either adding the entire injection profile (“profile injection”) or adding only the central “spike” portion of the injection profile nearest to the point-source position (“spike injection”). A collection of 75 059 archived vehicle count profiles from an operating border crossing were injected with a simulated low-energy gamma-ray point-source intended to emulate surrogates of highly enriched uranium or plutonium. Outcomes were assessed by means of injection curves (alarm rate vs. injection source size) and a derived measure, minimum detectable count rates (MDC) required to attain a detection probability of 95%. Results show that injection methodology combined with algorithm impacts study outcomes in different ways. For gross count results, centered spike injections yield higher detection sensitivity than centered profile injections, and random spike injections yield even higher detection sensitivity than centered spike injections. Conversely, for energy window ratio results, centered spike injections yield less sensitivity than centered profile injections, and random spike injections yield even less sensitivity than centered spike injections. These effects may be partially attributable to background suppression in the vehicle profile of detection statistics. Although the observed effects (up to 10%) are not large, the injection method impacts alarm rates from the two detection algorithms in opposite directions. These results inform methodological decisions and assessments of results in injection studies.

Weier, Dennis R.; Lo Presti, Charles A.; Bates, Derrick J.

2008-08-01

124

Comparative EIS study of a paste electrode containing zinc powder in neutral and near neutral solutions  

Microsoft Academic Search

.   The corrosion and passivation of Zn powder particles dispersed in a paste electrode immersed in 0.5 M Na2SO4 and 5×10–3 M Na2HPO4 solutions were studied mainly by electrochemical impedance spectroscopy. The role played by diffusion in the mechanism of\\u000a anodic oxidation of zinc powder particles has been shown. It was demonstrated that the anodic reactionof Zn powder in neutral\\u000a or near

N. Ibri?; J. Mirza-Rosca; A. Santana; T. Vi?an

2002-01-01

125

Spectroelectrochemical studies on dissolution and passivation of zinc electrodes in alkaline solutions  

Microsoft Academic Search

Electrochemical oxidation of zinc electrodes has been studied in 1.0 M KOH solutions employing cyclic voltammetric and in situ spectroelectrochemical techniques. The results indicate that three different processes, i.e., dissolution, prepassivation, and passivation, take place in different potential regions. Two optically different solution species absorbing at 250 and 290 nm, which are assigned to Zn(OH)â{sup 2⁻ and Zn(OH)â⁻}, respectively, are

Ming Cai; S. M. Park

1996-01-01

126

An ESR study of the electrocatalytic oxidation of hypophosphite on a nickel electrode  

Microsoft Academic Search

The electrocatalytic oxidation of hypophosphite on a nickel electrode has been studied by means of electron spin resonance spectroscopy (ESR) to obtain information about the anodic oxidation mechanism. A 16-line ESR spectrum was observed in the process of the electrocatalytic oxidation of hypophosphite when spin trap ?-pyridyl-N-tert-butyl nitrone (PBN) was added in the electrolytic solution. The spectra-line patterns and hyperfine

Yue Zeng; Yangcun Zheng; Shangci Yu; Ke Chen; Shaomin Zhou

2002-01-01

127

Material removal rate and electrode wear study on the EDM of silicon carbide  

Microsoft Academic Search

In this work, a material removal rate (MRR) and electrode wear (EW) study on the die-sinking electrical discharge machining (EDM) of siliconised or reaction-bonded silicon carbide (SiSiC) has been carried out. The selection of the above-mentioned conductive ceramic was made taking into account its wide range of applications in the industrial field: high-temperature gas turbines, bearings, seals and lining of

C. J. Luis; I. Puertas; G. Villa

2005-01-01

128

Electrochemical impedance studies of methanol oxidation on GC\\/Ni and GC\\/NiCu electrode  

Microsoft Academic Search

The electro-oxidation of methanol on nickel and nickel–copper alloy modified glassy carbon electrodes (GC\\/Ni and GC\\/NiCu) in a 1M NaOH solution at different concentrations of methanol was studied by the method of ac-impedance spectroscopy. Two semicircles in the first quadrant of a Nyquist diagram were observed for electro-oxidation of methanol on GC\\/Ni corresponding to charge transfer resistance and adsorption of

I. Danaee; M. Jafarian; F. Forouzandeh; F. Gobal; M. G. Mahjani

2009-01-01

129

Rotating ring-disk electrode and spectroelectrochemical studies on the oxidation of iron in alkaline solutions  

Microsoft Academic Search

The investigation of the anodic oxidation of iron in alkaline solutions is important because it is used as a cathodic reaction in Fe\\/Ni and Fe\\/air batteries, and it is also related to the corrosion of iron. The electrochemical oxidation of iron has been studied in concentrated alkaline solutions employing rotating ring-disk electrode voltammetric and in situ spectroelectrochemical techniques. While four

Haiyan Zhang

1994-01-01

130

Numerical study on the effect of electrode force in small-scale resistance spot welding  

Microsoft Academic Search

Since electrode force is an important process parameter in small-scale resistance spot welding (SSRSW), its effects on the electrical, thermal and mechanical behavior of the welding process when using direct current have been studied numerically in the present paper using the finite element method. The variations of contact radius, current density distribution and temperature profile at the sheet\\/sheet (S\\/S) and

B. H. Chang; Y. Zhou

2003-01-01

131

Variability of electrode positions using electrode caps.  

PubMed

We investigated the variability of electrode positions for a multi-channel, custom electrode cap placed onto participants' heads without taking scalp measurements. The electrode positions were digitized in a three-dimensional space for 10 young adult participants on three separate occasions. Positional variability was determined for 15 selected electrodes within the three-dimensional preauricular-nasion (PAN) coordinate system and from this system, angular coordinate variability was also determined. The standard deviations of the 15 selected electrodes ranged from 3.0 to 12.7 mm in the PAN system. These data resulted in a variability of 2.0 degrees to 10.4 degrees among the angular coordinates. The measurements indicated slightly greater variability of electrode positions compared to studies when electrodes were placed using scalp measurements. The implication of this study is that the use of electrode caps may not be appropriate when electroencephalographic (EEG) or evoked potential (EP) techniques depend on accurate electrode placement. Additionally, if a longitudinal study is performed, electrode locations should be checked to ensure that they conform with previous sessions. PMID:17929157

Atcherson, Samuel R; Gould, Herbert Jay; Pousson, Monique A; Prout, Tina M

2007-10-11

132

Ancient Astronomy: A Study of the Point Remove Mound Complex  

NASA Astrophysics Data System (ADS)

Artificial solstice markers are a common thread across many early civilizations. With the beginnings of early agriculture, the need to be able to predict the changes in season became an issue of utmost importance. Many Native American groups used artificial mounds to mark different astronomical events. Toltec Mounds (located southeast of Little Rock, AR) is a complex set of structures left behind by the area's native people that is known to have alignments with the summer and winter solstice as well as an equinox alignment. The Point Remove mound complex (located outside Morrilton, Arkansas, also known as site 3CN4) is a known archeological site that has not been well studied, therefore has never been checked for any form of astronomical alignment. The purpose of this project is to study the Point Remove Mound site and look for features of astronomical significance. Study of Toltec Mounds will serve as a baseline for comparison. Study of the site consists of aerial photographs, topographic maps, and GPS measurements. In addition to studying alignments within the site, the location of the mound complex will be studied with respect to other known complexes like Toltec Mounds and Spiro Mounds (Oklahoma).

Hankins, Matt; Burris, D. L.

2012-01-01

133

Problems in point-contact tunneling study on BSCCO  

NASA Astrophysics Data System (ADS)

Point-contact tunneling studies were carried out on BSCCO to investigate the influence of surface damages on the spectrum characteristic. Through the studies, it turned out that appearance of some additional structures (zero-bias conductance peak and fine structures inside or outside the superconducting gap) was strongly related with the surface cracks and layer-detachments caused by probe-contact. It also turned out that reproducible spectra could be observed only by damage free junctions with use of noble metal wire probes of 30?m?.

Murakami, H.; Ogami, T.; Qi, Y.; Sakai, K.; Ito, T.; Shigaki, I.; Jansen, A. G. M.; Wyder, P.

2000-07-01

134

Industrial hygiene study at the Anvil Points oil shale facility  

SciTech Connect

An industrial study was performed at the Department of Energy Anvil Points Oil Shale Mine and Retorting Facility near Rifle, Colorado. This study considered the potential industrial hygiene problems associated with the Paraho direct combustion retorting process and the related mining, crushing, disposal, and auxiliary operations. Air samples did not indicate any personal exposures in excess of existing industrial hygiene standards. However, area sampling did show that some operations would present significant exposures to some employees should such employees work full time in these areas. Commercial scale operations will require industrial hygiene control measures to control these potentially hazardous situations.

Garcia, L.L.; Schulte, H.F.; Ettinger, H.J.

1981-11-01

135

Thermal-stability studies of electrode materials for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

The thermal stability of lithium-ion batteries has recently attracted attention for two major reasons. (1) Attempts to make large-size cells used in power tools, E-bikes and EVs. Large cells have lower surface area to volume ratios and hence heat dissipation is more problematic than 18650-size cells. Safety problems, therefore, for large cells are more serious. (2) Next generation high-capacity electrodes will increase the energy density of lithium-ion cells meaning even an 18650-size cell may face safety concerns. This thesis presents studies of the thermal stability of electrode materials in electrolytes to understand their reactivity. A search for new positive electrode materials with high thermal stability was made. The thermal stability of two common electrode materials (Li0.81 C6 and Li0.5CoO2) in lithium-ion cells was studied by Accelerating Rate Calorimeter (ARC). Li0.81C 6 has much lower reactivity with lithium bis(oxalato)borate (LiBOB) electrolyte compared to LiPF6 electrolyte. It is not the case, however, for Li0.5CoO2. Oven tests of full LiCoO 2/C 18650-size cells with LiBOB or LiPF6 electrolytes, confirmed the ARC results. ARC was then used to study the reactivity of existing electrode materials. The thermal stability of a negative electrode material was found to increase with the binding energy of Li atoms hosted in the material. Li0.5VO 2 (B) has a higher lithium binding energy (2.45 eV vs. Li) than Li 0.81C6 (0.1 eV vs. Li) and Li7Ti5O 12 (1.55 eV) and it shows the highest thermal stability in EC/DEC among the three materials. The reactivity of two existing positive electrode materials, LiMn2O4 and LiFePO4, was studied. Cell systems expected to be highly tolerant to thermal abuse were suggested: LiFePO 4/C or Li4Ti5O12 in LiBOB electrolytes. The system, x Li[Ni1/2Mn1/2]O2 • y LiCoO2 • z Li[Li1/3Mn2/3]O2 (x + y + z = 1), was explored for new positive electrode materials with large capacity and high thermal stability. Li[(Ni0.5Mn0.5) xCo1-x]O2 (0.4 ? x ? 0.7) samples have excellent electrochemical properties and thermal stability and are being commercialized by industry. Li[(Ni0.5Mn0.5)xCo y(Li1/3Mn2/3)z]O2 (1/12 ? y ? 1/4, 1/6 ? z ? 1/3) samples have high specific capacity (200 mA h g-1), excellent cycling performance, and are safer than LiCoO2. The materials are suggested for energy cells used in cell phones, laptops, and so on.

Jiang, Junwei

136

The electrochemical study of promethazine hydrochloride in aqueous solution at glassy carbon electrode  

NASA Astrophysics Data System (ADS)

The electrochemical oxidation of promethazine hydrochloride (PMT) was studied on glassy carbon electrode (GCE) whose surface area (6.0 x 10 -3 cm2) was determined electrochemically. The reference electrode was a commercial calomel electrode and the counter electrode was a wound platinum wire. The electrochemical reaction was conducted at room temperature in a one-electrochemical cell using an electrochemical analyzer supplied by Cypress Systems. The important electrochemical parameters such as the redox potential, Eo, the half-wave potential, E 1/2, the diffusion coefficient, D, the number of electrons transferred in the reaction, n, the electron transfer coefficient, alpha, and the heterogeneous rate constant, ks, were determined in a solution of 4.0 x 10 -3 M. These parameters were used in formulating a plausible reaction mechanism of this compound in an aqueous solution. The effect of different surfactants on its stability was also studied. The results of the obtained data indicate that: (1) The electrochemical parameters obtained for this compound were: Eo = 0.60V, E 1/2 = 0.67V, D = 3.9 x 10-5 cm2/s, n = 1mole, alpha = 0.33, ks = 2.45 x 10-4; (2) The peak potential was observed at about 0.60--0.80 V and was linearly dependent on the concentration; (3) The observed current intensity which was determined as a function of the voltammetric scan rate, was seen to be linearly related to the square root of the scan rate; (4) The observed peak potential and the peak current were influenced by the pH of the solution; (5) The stability of PMT in different surfactant (cationic, anionic and non-ionic) shows a decrease when compared to the control solution over twenty days. During this period, it was observed that the anionic and the non-ionic surfactants were more effective stabilizers than the cationic surfactants.

Tambe Takaw, Robert

137

Dry electrodes for electrocardiography.  

PubMed

Patient biopotentials are usually measured with conventional disposable Ag/AgCl electrodes. These electrodes provide excellent signal quality but are irritating for long-term use. Skin preparation is usually required prior to the application of electrodes such as shaving and cleansing with alcohol. To overcome these difficulties, researchers and caregivers seek alternative electrodes that would be acceptable in clinical and research environments. Dry electrodes that operate without gel, adhesive or even skin preparation have been studied for many decades. They are used in research applications, but they have yet to achieve acceptance for medical use. So far, a complete comparison and evaluation of dry electrodes is not well described in the literature. This work compares dry electrodes for biomedical use and physiological research, and reviews some novel systems developed for cardiac monitoring. Lastly, the paper provides suggestions to develop a dry-electrode-based system for mobile and long-term cardiac monitoring applications. PMID:23969948

Meziane, N; Webster, J G; Attari, M; Nimunkar, A J

2013-08-23

138

Impact of Point-Source Injection Methodologies on Injection Studies  

SciTech Connect

Effective interdiction of illicit radioactive material requires detection algorithms that are sensitive to material of interest while insensitive to material of no interest. Injection studies are used to assess the detection sensitivities to threat scenarios by various detection algorithms. In injection studies, gamma-ray spectra for varying source strengths representing particular radioisotopes and shielding configurations are added to archived vehicle count time-profiles. Observed alarm rates are calculated and analyzed to address experimental questions. Numerous decisions need to be made about configuring injection studies, including two important methodological factors that emulate actual field conditions: point-source position and temporal shape. Understanding the relative impact of different methods on outcome measures is vital for comparing results of injection studies.

Weier, Dennis R.; Lopresti, Charles A.; Bates, Derrick J.

2008-08-11

139

Reaction kinetics and x-ray absorption spectroscopy studies of yttrium containing metal hydride electrodes  

SciTech Connect

This was a study of electrode degradation mechanisms and the reaction kinetics of LaNi{sub 4.7}Sn{sub 0.3}, La{sub (1{minus}x)} Y{sub x}Ni{sub 4.7}Sn{sub 0.3} (x = 0.1, 0.2, and 0.3) and La{sub 0.7}Y{sub 0.3}Ni{sub 4.6}Sn{sub 0.3}Co{sub 0.1} metal hydride electrodes. Alloy characterization included x-ray diffraction (XRD), x-ray absorption (XAS), hydrogen absorption in a Sieverts apparatus, and electrochemical cycling of alloy electrodes. The atomic volume of H was determined for two of the alloys. Electrochemical kinetic measurements were made using steady state galvanostatic measurements, galvanodynamic sweep, and electrochemical impedance techniques. XAS was used to examine the degree of corrosion of the alloys with cycling. Alloying with Y decreased the corrosion rate. The results are consistent with corrosion inhibition by a Y containing passive film. The increase in the kinetics of the hydrogen oxidation reaction (HOR) with increasing depth of discharge was much greater on the Y containing alloys. This may be due to the dehydriding of the catalytic species on the surface of the metal hydride particles.

Ticianelli, E.A.; Mukerjee, S.; McBreen, J.; Adzic, G.D.; Johnson, J.R.; Reilly, J.J. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science

1998-12-31

140

In situ X-ray absorption spectroscopy studies of metal hydride electrodes  

SciTech Connect

In situ X-ray absorption spectroscopy (XAS) studies were done on three metal hydride electrodes, LaNi{sub 5}, LaNi{sub 4.8}Sn{sub 0.2}, La{sub 0.8}Ce{sub 0.2}Ni{sub 4.8}Sn{sub 0.2}, in 6M KOH. Ex situ measurements were also made on dry uncycled electrodes and on material from an La{sub 0.8}Ce{sub 0.2}Ni{sub 4.8}Sn{sub 0.2} electrode that had been cycled 25 times. Comparison of the in situ XAS at the Ni K and at the La L{sub 3} edge of charged and discharged electrodes indicates large changes in the electronic and structural characteristics on introduction of hydrogen. Results at the Ce L{sub 3} edge in La{sub 0.8}Ce{sub 0.2}Ni{sub 4.8}Sn{sub 0.2} show a transition from a mixed valent to {alpha} to a {gamma}-like Ce state as the lattice expands during charge. Ex situ x-ray absorption near-edge structures (XANES) at the Ni K edge indicate that the additions of either Ce or Sn fill empty Ni 3d states. The Ni K edge extended x-ray absorption fine structures (EXAFS) for all three alloys in the dry uncharged state were similar, indicating that minor substitutions for either the A or B component does not substantially change the structure. The Sn substitution causes an increase both in a and c axis as evidenced from increase in the Ni-Ni and the Ni-La distances. Partial substitution of La by Ce causes a slight contraction in the Ni-La distance. The Ni XANES and EXAFS indicate that about 6% of the Ni in the La{sub 0.8}Ce{sub 0.2}Ni{sub 4.8}Sn{sub 0.2} corroded after 25 cycles. Ce XANES on the cycled electrode indicates some corrosion of Ce and the formation of Ce (III) state. The results indicate that XAS is a very useful technique for the study of alloy hydrides, particularly the role of electronic structure, the environment around minor constituents, and the corrosion of individual components.

Mukerjee, S.; McBreen, J.; Reilly, J.J.; Johnson, J.R.; Adzic, G. [Brookhaven National Laboratory, Upton, NY (United States). Dept. of Applied Science; Petrov, K.; Kumar, M.P.S.; Zhang, W.; Srinivasan, S. [Texas A and M Univ., College Station, TX (United States). Center for Electrochemical Systems and Hydrogen Research

1995-07-01

141

The study of electron transfer in advanced materials (electrodes for Li-ion batteries or catalysts)  

NASA Astrophysics Data System (ADS)

Mössbauer Spectroscopy (MS) is really suitable to study local electronic structures. Its hyperfine parameters, isomer shift (IS) and quadrupole splitting (QS) allow to characterize the oxidation state and coordination of the probed element. So, the capabilities of this powerful technique have been highlighted for the study of electron transfer occurring during electrochemical or catalytic processes. Several examples illustrate how MS can be used for the determination of reaction mechanisms in new electrode materials of Li-ion batteries (Sb or Sn-based, Ti oxides) or reforming catalysts (supported bimetallic PtSn catalysts). Deeper insight into the mechanisms determining the electrochemical or catalytic performances can be expected.

Jumas, Jean-Claude; Womes, Manfred; Lippens, Pierre-Emmanuel; Olivier-Fourcade, Josette

2008-02-01

142

Numerical study on the electron—wall interaction in a Hall thruster with segmented electrodes placed at the channel exit  

NASA Astrophysics Data System (ADS)

Electron—wall interaction is always recognized as an important physical problem because of its remarkable influences on thruster discharge and performance. Based on existing theories, an electrode is predicted to weaken electron—wall interaction due to its low secondary electron emission characteristic. In this paper, the electron—wall interaction in an Aton-type Hall thruster with low-emissive electrodes placed near the exit of discharge channel is studied by a fully kinetic particle-in-cell method. The results show that the electron—wall interaction in the region of segmented electrode is indeed weakened, but it is significantly enhanced in the remaining region of discharge channel. It is mainly caused by electrode conductive property which makes equipotential lines convex toward channel exit and even parallel to wall surface in near-wall region; this convex equipotential configuration results in significant physical effects such as repelling electrons, which causes the electrons to move toward the channel center, and the electrons emitted from electrodes to be remarkably accelerated, thereby increasing electron temperature in the discharge channel, etc. Furthermore, the results also indicate that the discharge current in the segmented electrode case is larger than in the non-segmented electrode case, which is qualitatively in accordance with previous experimental results.

Qing, Shao-Wei; E, Peng; Duan, Ping; Xu, Dian-Guo

2013-08-01

143

Point of View: Leadership Studies from Different Perspectives  

ERIC Educational Resources Information Center

|By adopting the dictum that all knowledge is knowledge from a point of view, educators can arrange the literature on leadership into nine categories from three conceptually distinct points of view, namely the Leader, the Follower, and the Investigator. Students who come to appreciate and account for point of view not only increase their…

Harter, Nathan

2012-01-01

144

Point Contact Andreev Reflection Studies on Iron Pnictide Superconductors  

NASA Astrophysics Data System (ADS)

We have systematically investigated the temperature, doping and the directional dependence of the gap structure for various types of single crystal iron pnictide superconductors by point contact Andreev reflection spectroscopy. Our studies were performed on highly transparent junctions evidenced by sharp and dramatic conductance enhancements at low temperatures. For the 122 family, despite some small features occasionally observed on the spectroscopy curves which may originate from the multiband superconductivity, a more conclusive characteristic of our obtained spectra is the presence of one predominant superconducting gap. By applying the BTK model, we find that the determined gap size scales well with the transition temperature, resulting in the 2?/kBTC value of ˜ 3.1 for both potassium doped and cobalt doped single crystals. Directional studies suggest that this gap is highly isotropic. Results on chalcogenide and nickel doped 122 superconductors will also be discussed. [X. H. Zhang et al., Phys. Rev. B 81, 024518 (2010)].

Zhang, Xiaohang; Saha, S. R.; Butch, N. P.; Kirshenbaum, K.; Paglione, J.; Greene, R. L.; Takeuchi, I.; Oh, Y.-S.; Liu, Y.; Yan, L. Q.; Kim, K.-H.

2011-03-01

145

Prussian Blue Modified Carbon Nanotube Paste Electrodes: A Comparative Study and a Biochemical Application  

Microsoft Academic Search

Prussian Blue modification of Single Walled Carbon Nanotubes and the successive assembling of paste electrodes is presented in this article for the first time. The electrochemical feature of such electrodes have been fully evaluated with CV and amperometric experiments. Prussian Blue Nanotube Paste electrodes showed a high sensitivity towards hydrogen peroxide with a LOD of 7.4 × 10 M. They also proved to

Francesco Ricci; Aziz Amine; Danila Moscone; Giuseppe Palleschi

2003-01-01

146

A study of rechargeable zinc electrodes for alkaline cells requiring anodic limitation  

Microsoft Academic Search

Problems associated with the cyclic operation of zinc electrodes in rechargeable alkaline cells for which anodic limitation is required are investigated. Experiments were conducted to determine the influence of electrolyte additives and cell construction on the capacity loss of limited zinc electrodes during cycling; current-voltage diagrams for zinc electrodes within the potential range of passivation and of hydrogen evolution were

L. Binder; W. Odar; K. Kordesch

1981-01-01

147

A Study of Tool Electrode Materials and Flushing Techniques in micro EDM  

Microsoft Academic Search

The feasibility of using foil materials as tool electrode in micro electro discharge machining (micro EDM) has provided new machining alternative for the spark erosion of micro grooves. To complement the widely used (and expensive) micro EDM tool electrode material (tungsten), two cost effective materials namely graphite and stainless steel have been tried as tool electrodes. Recent technological innovations have

Murali Meenakshi Sundaram; Yeo Swee Hock; Kamlakar P. Rajurkar

148

I Situ Structural Study of Underpotential Deposition and Electrocatalysis on GOLD(111) Electrodes  

NASA Astrophysics Data System (ADS)

This thesis work has studied systems of Bi, Pb, Ag, and Hg underpotential deposition (UPD) on Au(111) electrodes. The application of the atomic force microscope (AFM), the scanning tunneling microscope (STM), and the surface x-ray scattering (SXS) to these UPD studies has provided in situ measurements from which we investigate factors that determine UPD surface structures and correlate these structures with surface reactivity. For all the UPD systems in this thesis work, atomic level features of the electrode surface have been revealed. In the case of Pb UPD, Pb starts to deposit by forming islands which exhibit a hexagonal close packed structure of Pb adatoms, while, in the other systems, the UPD adatoms form open lattices. In the Bi and Pb studies, we correlate the activities of the modified surface toward electroreduction of H_2O_2 with the adlattice structures. A heterobimetallic bridge model for H_2O_2 on the surface could explain the enhanced reactivity. The full monolayers of Bi and Hg, rhombohedral metals, form rectangular lattice structures on the hexagonal Au(111) surfaces. The partial charge retention on the Bi and Hg adatom opens the adlayer structure when the coverage is less than a full monolayer. The structure of the first submonolayers of Ag UPD is electrolyte-dependent. The electrode surface exhibits 3 x 3 and 4 x 4 overlayer structures in solutions containing sulfate and nitrate, respectively. In perchloric acid another open structure is observed and a close-packed monolayer is formed in acetic acid. The different monolayer structures give rise to packing densities which correlate with electrolyte size. This implies that the anions participate in reducing metal ions.

Chen, Chun-Hsien

149

Studies on the electrochemical and thermodynamic behaviour of Hg-HgS electrode in the presence of sulphide ions  

Microsoft Academic Search

Mercury-mercury (II) sulphide electrode has been prepared and its electrochemical and thermodynamic behaviour has been studied\\u000a in different media. The electrode is found to show Nernstian response to pS (? log [S2?]) over the range 5.19–10.38. In the pH range 7.96–11.98, at constant [S2?]v, its response is also Nernstian. The values of thermodynamic functions, viz., ?G0. ?H0, and ?S0 for

Pravin Chandra Katiyar; Mukhtar Singh

1988-01-01

150

Chemically sensitized ormosil-modified electrodes—Studies on the enhancement of selectivity in electrochemical oxidation of hydrogen peroxide  

Microsoft Academic Search

The chemically sensitized ormosil-modified electrodes were made by encapsulating potassium ferricyanide together with organic-ionophore (dibenzo-18-crown-6\\/Nafion) within ormosil films. The modified electrodes were studied in details from following angles; (1) the effect of variation in potassium ferricyanide concentration in ormosil films; (2) the effect of variation in dibenzo-18-crown-6 concentration in ormosil films; (3) effect of pH on the electrochemistry of ormosil-modified

P. C. Pandey; B. Singh; R. C. Boro; C. R. Suri

2007-01-01

151

A study of die helical thread cavity surface finish made by Cu-W electrodes with planetary EDM  

Microsoft Academic Search

An experimental research study intended for the application of a planetary electrical discharge machining (EDM) process with\\u000a copper-tungsten (Cu-W) electrodes in the surface micro-finishing of die helical thread cavities made with AISI H13 tool steel\\u000a full-hardened at 53 HRC is presented. To establish the EDM parameters’ effect on various surface finishing aspects and metallurgical\\u000a transformations, three tool electrode Cu-W compositions

José Carvalho Ferreira

2007-01-01

152

Study of electropolishing of ferrous alloys using rotating-disk electrodes  

SciTech Connect

This work deals with electropolishing of ferrous materials ranging from pure iron through carbon steels, with increasing carbon content, to a few low-alloy steels. The characteristics of electropolishing stainless and acid-proof steels are well known, and for this reason were not considered in this research. Studies were performed on the rotating disk electrode system under controlled electrochemical and hydrodynamic conditions. The purpose was to establish conditions at which the best surface finish, after electropolishing of different types of ferrous alloys, may be achieved. The work involved investigations over a wide range of applied current density, mass loss, and current efficiency.

Hryniewich, T.; Muller, R.H.; Tobias, C.W.

1981-06-01

153

Antimony electrodes  

Microsoft Academic Search

Antimony electrodes are clinically useful because of their low cost and simple construction; they have no glass to break. There is only a few hundred ohms resistance between an antimony pH electrode and the reference electrode so that the voltage generated can be recorded with simple low-impedance recorders linked to microcomputers. We used antimony pH electrodes with silver-silver chloride electrodes

Antone R. Opekun; J. Lacey Smith; David Y. Graham

1990-01-01

154

Synchrotron x-ray diffraction studies of the structural properties of electrode materials in operating battery cells  

SciTech Connect

Hard x rays from a synchrotron source were utilized in diffraction experiments which probed the bulk of electrode materials while they were operating {ital in} {ital situ} in battery cells. Two technologically relevant electrode materials were examined; an {ital AB}{sub 2}-type anode in a nickel{endash}metal{endash}hydride cell and a LiMn{sub 2}O{sub 4} cathode in a Li-ion {open_quote}{open_quote}rocking chair{close_quote}{close_quote} cell. Structural features such as lattice expansions and contractions, phase transitions, and the formation of multiple phases were easily observed as either hydrogen or lithium was electrochemically intercalated in and out of the electrode materials. The relevance of this technique for future studies of battery electrode materials is discussed. {copyright} {ital 1996 American Institute of Physics.}

Thurston, T.R.; Jisrawi, N.M. [Department of Physics, Brookhaven National Laboratory, Upton, New York, 11973 (United States); Mukerjee, S.; Yang, X.Q.; McBreen, J. [Department of Applied Science, Brookhaven National Laboratory, Upton, New York, 11973 (United States); Daroux, M.L.; Xing, X.K. [Gould Electronics, Inc., Eastlake, Ohio 44095-4001 (United States)

1996-07-01

155

Turbulent mixing and deposition studies for single point aerosol sampling  

NASA Astrophysics Data System (ADS)

A generic mixing system has been developed which creates suitable conditions for single point stack sampling of effluent air emission points. Results show that the system performance is well within the EPA mixing criteria---the COVs for velocity, tracer gas concentration and 10 mum AD aerosol particles are less than half of the EPA permissible level of 20%. Experiments were conducted to characterize the degree of mixing at downstream locations as affected by several types of flow disturbances, including 90° elbows and commercial static mixing devices. It was found that the mixing is impacted by the upstream flow turbulence and that the use of static mixing elements can greatly enhance the mixing process. A stack system has been characterized which creates conditions suitable for single point representative sampling. The stack system could be used in both existing and new stack or duct configurations. It could also be used as an aerosol wind tunnel for testing various sampling devices. Results show that the system performance is well within the EPA permissible limits. A mixing model has been developed which can predict mixing of tracer gas in turbulent air flows in piping systems comprised of a series of 90° elbows. The model uses the concept of an equivalent length of straight pipe that would produce the same degree of mixing as the mixing element under consideration. There is good agreement between experimental and predicted results. Aerosol penetration through flow splitters was experimentally and numerically investigated. A surface plot was generated from the experimental data to predict aerosol penetration as a function of the Stokes number and the bifurcation angle between the two outlets of the splitters. The developed correlation is valid in the ranges of 0.034 ? Stk ? 1.248; 2,556 ? Re ? 13,630; and, 30° ? theta ? 180°, and should be a useful sub-model for predicting aerosol particle losses in flow splitters in software programs, e.g., DEPOSITION. Numerical studies were conducted with a commercial computational fluid dynamics (CFD) software, FLUENT, and a Lagrangian particle tracking code. Good agreement was found between the experimental and numerical results.

Gupta, Rajiv

1999-11-01

156

A preliminary study of the effect of electrode placement in order to define a suitable location for two electrodes and obtain sufficiently reliable ECG signals when monitoring with wireless system.  

PubMed

Most countries face high and increasing rates of cardiovascular disease. Each year, heart disease kills more Americans than cancer. Therefore, there has been a promising market for portable ECG equipment and it is increasing. To use portable ECG measuring devices, it is essential to define a suitable location for the measuring as we need to reduced electrode size and distance. This research proposes to study how the inter-electrode distance affects the signal and how the electrode pair should be placed on the chest in order to obtain a sufficiently reliable ECG signal to detect heart arrhythmias in any environment, such as home or work. Therefore, we developed a compact, portable patch type ambulatory ECG monitoring system, Heart Tracker, using a microprocessor for preliminary study of signal analysis. To optimize the electrode arrangement in wireless environment, we compared HT and standard 12 lead with changing electrode position. PMID:23366341

Noh, Hyung Wook; Jang, Yongwon; Lee, I B; Song, Yoonseon; Jeong, Ji-Wook; Lee, Sooyeul

2012-01-01

157

Comparative study of maximum power point tracking algorithms  

Microsoft Academic Search

Maximum power point trackers (MPPTs) play an important role in photovoltaic (PV) power systems because they maximize the power output from a PV system for a given set of conditions, and therefore maximize the array efficiency. Thus, an MPPT can minimize the overall system cost. MPPTs find and maintain operation at the maxi- mum power point, using an MPPTalgorithm. Many

D. P. Hohm; M. E. Ropp

2003-01-01

158

Electrochemical study of NO conversion from Fe(II)-EDTA-NO complex on Pt electrodes  

SciTech Connect

The Fe(II)-ethylenediaminetetraacetic acid (EDTA)-NO complex formed by interaction of gaseous nitrous oxide (ca. 200 ppm) and Fe(II)-EDTA in aqueous solution was found to be convert3ed electrochemically on platinum electrodes at potentials below ca. {minus}0.6 V{sub SCE}, indicating the cathodic reduction of NO. In addition to the previous studies by which the indirect conversion of NO with dithionite as a redox mediator was confirmed, the present results should elucidate the possibility of the direct electrochemical conversion of NO in mediator-free solutions. To clearly separate this process from other reactions in the system, the electrochemical behavior of Fe(II)-EDTA and Fe(III)-EDTA was studied over a wide potential range at different pH values. Five electrode reactions could be identified, which include the oxidation/reduction of Fe{sup 2+}/Fe{sup 3+} in the EDTA complex, the reduction of EDTA, the reduction of protons, the cathodic deposition of iron, and the anodic decomposition of EDTA. The electrochemical deposition of iron from Fe(II)-EDTA at potentials E < {minus}1.0 V{sub SCE} was confirmed by electrochemical quartz crystal microbalance measurements and energy-dispersive x-ray analysis.

Juzeliunas, E.; Juettner, K. [Karl-Winnacker-Inst. der DECHEMA e.V., Frankfurt am Main (Germany)

1998-01-01

159

Tricritical point in ferroelastic ammonium titanyl fluoride: NMR study  

SciTech Connect

Ionic mobility and phase transitions in ammonium titanyl pentafluoride (NH{sub 4}){sub 3}TiOF{sub 5} were studied using the {sup 19}F and {sup 1}H NMR data. The high-temperature phase (I) is characterized by spherically symmetric (isotropic) reorientation of [TiOF{sub 5}]{sup 3-} anions and by uniaxial reorientation of these anions in the ferroelastic phase II. A previously unknown second-order phase transition to the low-temperature modification (NH{sub 4}){sub 3}TiOF{sub 5}(III) was found at 205 K. The transition is accompanied by hindering of uniaxial rotations of [TiOF{sub 5}]{sup 3-} anions and by noticeable change of {sup 19}F magnetic shielding tensor associated with the influence of pseudo-Jahn-Teller effect. A pressure-induced tricritical point with coordinates p{sub TCR{approx}}2 kbar and T{sub TCR{approx}}170 K is estimated on the base of {sup 19}F NMR chemical shift data, and previously studied p-T diagram of (NH{sub 4}){sub 3}TiOF{sub 5}. - Graphical abstract: p-T phase diagram of (NH{sub 4}){sub 3}TiOF{sub 5}.

Kavun, V.Ya. [Institute of Chemistry, FEB RAS, Ave. Stoletiya, 159, 690022 Vladivostok (Russian Federation); Kozlova, S.G., E-mail: sgk@niic.nsc.r [Nikolaev Institute of Inorganic Chemistry, SB RAS, Ave. Lavrenteva, 3, 630090 Novosibirsk (Russian Federation); Laptash, N.M; Tkachenko, I.A. [Institute of Chemistry, FEB RAS, Ave. Stoletiya, 159, 690022 Vladivostok (Russian Federation); Gabuda, S.P [Nikolaev Institute of Inorganic Chemistry, SB RAS, Ave. Lavrenteva, 3, 630090 Novosibirsk (Russian Federation)

2010-09-15

160

Study of C-coated LiFe{sub 0.33}Mn{sub 0.67}PO{sub 4} as positive electrode material for Li-ion batteries  

SciTech Connect

Commercial C-LiFe{sub 0.33}Mn{sub 0.67}PO{sub 4} positive electrode material has been investigated by {sup 57}Fe Moessbauer Spectroscopy (MS), X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS). The combined use of these experimental techniques provides a better understanding of the electrochemical reaction involved during cycling. {sup 57}Fe MS is very efficient to directly follow oxidation state of Fe in the electrode, and gives surprisingly indirect information on the oxidation state of Mn as observed by XAS and XPS. The electrochemical mechanism is proposed based from in situ and operando investigations using both MS and XAS, and is consistent with XPS surface studies. XPS analysis of the electrodes at the end of charge (4.4 V) reveals enhanced electrode/electrolyte interface reactivity at this high potential. Aging of C-LiFe{sub 0.33}Mn{sub 0.67}PO{sub 4}/Li cells after 50 cycles at 60 Degree-Sign C indicates a rather good electrochemical behavior (low capacity fading) of the electrode material. Both {sup 57}Fe MS and XPS (Mn 2p and Fe 2p) clearly show no modification on Fe and Mn oxidation state compared to fresh electrode confirming the good electrochemical performances. - Graphical abstrct: Quantitative evaluation of the Fe{sup 3+} and Mn{sup 3+} content during the first charge/discharge cycle obtained from K-edge XANES spectra of C-LiFe{sub 0.33}Mn{sub 0.67}PO{sub 4} recorded upon cell operation at RT with C/10 rate. During the charge co-existence of Fe and Mn oxidation is observed between points 2 and 4 of the potential curve. At the end of the charge the cut-off voltage limits the oxidation at about 93%. Highlights: Black-Right-Pointing-Pointer C-LiFe{sub 0.33}Mn{sub 0.67}PO{sub 4} electrode material upon cycling vs. metallic lithium. Black-Right-Pointing-Pointer {sup 57}Fe Moessbauer spectroscopy is a (in)direct probe for Fe(Mn) oxidation state. Black-Right-Pointing-Pointer Both K-Fe and K-Mn edges XAS show a simultaneous oxidation of Fe{sup 2+} and Mn{sup 2+} in a small range of compositions. Black-Right-Pointing-Pointer Surface analysis from XPS allows reveals slight differences at the surface of the electrode with respect to the bulk.

Perea, A. [Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1 Agregats, Interfaces et Materiaux pour l'Energie CC 1502, Place Eugene Bataillon, 34095 Montpellier, Cedex 5 (France); Castro, L. [IPREM-ECP, Universite de Pau, Helioparc, 2 av. Pierre Angot, 64053 Pau, Cedex 9 (France); Aldon, L., E-mail: laurent.aldon@um2.fr [Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1 Agregats, Interfaces et Materiaux pour l'Energie CC 1502, Place Eugene Bataillon, 34095 Montpellier, Cedex 5 (France); Stievano, L. [Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1 Agregats, Interfaces et Materiaux pour l'Energie CC 1502, Place Eugene Bataillon, 34095 Montpellier, Cedex 5 (France); Dedryvere, R.; Gonbeau, D. [IPREM-ECP, Universite de Pau, Helioparc, 2 av. Pierre Angot, 64053 Pau, Cedex 9 (France); Tran, N.; Nuspl, G. [Sued-Chemie AG, Ostenriederstr. 15, D-85368 Moosburg (Germany); Breger, J.; Tessier, C. [SAFT, 111-113 bd. Alfred Daney, 33074 Bordeaux, Cedex (France)

2012-08-15

161

Waveguide surface plasmon resonance studies of surface reactions on gold electrodes.  

PubMed

We describe the fabrication and characterisation of gold-coated graded index channel waveguide sensors designed for simultaneous electrochemical and surface plasmon resonance studies. The active sensing electrode area is a thin gold film between 0.5 and 5 mm in length and 200 microm wide deposited on top of a 3 microm wide waveguide which forms one arm of a Y-junction while the other arm of the Y-junction serves as a reference. Using these devices we have measured simultaneously the changes in transmittance through the device whilst carrying out cyclic voltammetry in either sulfuric or perchloric acid solution or during the deposition of an UPD layer of copper at the gold surface. In all cases we obtain stable and reproducible results which demonstrate the very high sensitivity of the devices to sub-monolayer changes occurring at the gold electrode surface. The response of these integrated optoelectrochemical devices is discussed in terms of a numerical model for the propagation of light within the waveguide structure. PMID:12227565

Abanulo, J C; Harris, R D; Sheridan, A K; Wilkinson, J S; Bartlett, P N

2002-01-01

162

Chalk Point steam electric station studies Patuxent Estuary studies: ichthyoplankton population studies, 1979. Final report  

SciTech Connect

Two years of riverwide ichthyoplankton data were collected as a part of a series of studies at the Chalk Point Steam Electric Station (SES) to contribute data necessary to evaluate information to be presented in the 316 variance demonstration document scheduled for Units 1 and 2 of this facility during 1981. These studies also provided information on the regional spatial and temporal distribution of fish eggs and larvae required to put nearfield studies conducted by the Potomac Electric Power Company into regional context. The principal species collected were white perch, striped bass, bay anchovy, sliversides, naked goby, yellow perch, and clupeids.

Mihursky, J.A.; Wood, K.V.; Kerig, S.; Setzler-Hamilton, E.M.

1980-04-01

163

Structural and electrochemical study of positive electrode materials for rechargeable lithium ion batteries  

NASA Astrophysics Data System (ADS)

The research presented in this dissertation focuses on a combined study of the electrochemistry and the structure of positive electrode materials for Li ion batteries. Li ion batteries are one of the most advanced energy storage systems and have been the subject of numerous scientific studies in recent decades. They have been widely used for various mobile devices such as cell phones, laptop computers and power tools. They are also promising candidates as power sources for automotive applications. Although intensive research has been done to improve the performance of Li ion batteries, there are still many remaining challenges to overcome so that they can be used in a wider range of applications. In particular, cheaper and safer electrodes are required with much higher reversible capacity. The series of layered nickel manganese oxides [NixLi 1/3-2x/3Mn2/3- x/3]O2 (0 < x < 1/2) are promising alternatives for Li2CoO2, the commercial positive electrode materials in Li ion batteries, because of their lower cost and higher safety and abuse tolerance, when lithium is removed from their structure. Compounds with x<1/2, in which the total Li content is higher than transition metal content, are referred as "Li-excess" materials. The "Li2MnO3-like" region is always present in this type of materials, and the overcapacity is obtained in the first charge process, which is not reversible in the following cycles. A combined X-ray diffraction, solid state nuclear magnetic resonance and X-ray absorption spectroscopy study is performed to investigate the effect of synthetic methods on the structure, to probe the structural change of the materials during cycling and to understand the electrochemical reaction mechanism. The conversion compounds are also investigated because of their high capacities. Since the various compounds have different voltage windows, they can have potential applications as both cathodes and anodes. Solid state nuclear magnetic resonance is used to study the change in the local environment of the structure during the cycling process. Two systems are included in this work, including iron fluorides and Cu-containing materials. A comparison study has been performed on FeF3 and FeF2. Different discharge reaction mechanisms are clarified for each compound, and possible phase transitions are proposed as well. As for the Cu-containing systems, three compounds were chosen with different anions: CuS, CuO and CuF2. The reaction mechanisms are studied by 63Cu, 7Li and 19F NMR and supported by powder X-ray diffraction.

Jiang, Meng

164

The Point Is There Is No Point: Miasmic Cynicism and Cultural Studies Composition.  

ERIC Educational Resources Information Center

|Explores cynicism and its institutional and pedagogical impact on cultural studies composition by discussing how cynicism in contemporary emotion culture can be understood as an effect of the shifting emotional identifications in postmodernism, particularly in light of mass-mediated consciousness. Argues that it is through cultural studies

Langstraat, Lisa

2002-01-01

165

An Investigation of the Hypoalgesic Effects of TENS Delivered by a Glove Electrode  

PubMed Central

This randomized, placebo-controlled, blinded study investigated the hypoalgesic effects of high-frequency transcutaneous electrical nerve stimulation (TENS) delivered via a glove electrode compared with standard self-adhesive electrodes. Fifty-six TENS-naïve, healthy individuals (18 to 50 years old; 28 men, 28 women) were randomly allocated to 1 of 4 groups (n = 14 per group): glove electrode; placebo TENS using a glove electrode; standard electrode; and no treatment control. Active TENS (continuous stimulus, 100 Hz, strong but comfortable intensity) was applied to the dominant forearm/hand for 30 minutes. Placebo TENS was applied using a burst stimulus, 100-Hz frequency, 5-second cycle time for 42 seconds, after which the current amplitude was automatically reset to 0 mA. Pressure pain thresholds (PPTs) were recorded from 3 points on the dominant and nondominant upper limbs before and after TENS. Statistical analyses of dominant PPT data using between-within groups ANOVA showed significant differences between groups at all 3 recording points (P = .01). Post hoc Scheffe tests indicated no significant difference between the standard electrode and glove electrode groups. There was a significant hypoalgesic effect in the standard electrode group compared with the control group and between the glove electrode group and both the control and placebo TENS groups. There was no significant interactive effect between time and group at any of the recording points (P > .05). Perspective This study presents a comparison of the hypoalgesic effects of 2 different types of TENS electrode, a novel glove electrode and standard self-adhesive rectangular electrodes. The glove electrode provides a larger contact area with the skin, thereby stimulating a greater number of nerve fibers. The results show that both electrodes have similar hypoalgesic effects and therefore give the clinician another choice in electrode.

Cowan, Stephen; McKenna, Joanne; McCrum-Gardner, Evie; Johnson, Mark I.; Sluka, Kathleen A.; Walsh, Deirdre M.

2009-01-01

166

Comprehensive Study of Microgel Electrode for On-Chip Electrophoretic Cell Sorting  

Microsoft Academic Search

We have developed an on-chip cell sorting system and microgel electrode for applying electrostatic force in microfluidic pathways in the chip. The advantages of agarose electrodes are 1) current-driven electrostatic force generation, 2) stability against pH change and chemicals, and 3) no bubble formation caused by electrolysis. We examined the carrier ion type and concentration dependence of microgel electrode impedance,

Akihiro Hattori; Kenji Yasuda

2010-01-01

167

Quantitative evaluation of electrodes for external urethral sphincter electromyography during bladder-to-urethral guarding reflex  

Microsoft Academic Search

Purpose  Accuracy in the recording of external urethral sphincter (EUS) electromyography (EMG) is an important goal in the quantitative\\u000a evaluation of urethral function. The aim of this study was to quantitatively compare electrode recordings taken during tonic\\u000a activity and leak point pressure (LPP) testing.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Several electrodes, including the surface electrode (SE), concentric electrode (CE), and wire electrode (WE), were placed\\u000a on

James E. Steward; Jessica D. Clemons; Paul J. Zaszczurynski; Robert S. Butler; Margot S. Damaser; Hai-Hong Jiang

2010-01-01

168

Preparation of polymer-modified electrodes: A literature and experimental study  

SciTech Connect

A literature review is presented on the field of polymer modified electrodes which can be electrochemically generated. It is suggested that a possible application of these polymer modified electrodes is as a regeneratable catalysis packing material for use in couter-current exchange columns. Secondly, there is a presentation of experimental results dealing with possible electrode modification using difluoro- and dimethyl- phenols and fluorinated derivatives of styrene, benzoquinone and hydroquinone. It appears that dimethylphenol shows the most potential of the monomers experimentally tested in providing a stable polymer modified electrode surface. 170 refs., 31 figs., 1 tab.

Jayanta, P.S.; Ishida, Takanobu

1991-05-01

169

Using Digital Simulation to Study Hydroquinone Oxidation on Porous Electrodes by Cyclic Voltammetry  

NASA Astrophysics Data System (ADS)

Digital simulation is a very useful tool to understand dynamic electrochemical processes. Composite porous electrodes, comprising a micro-porous material provide electrodes with very high effective areas and can also make use of the molecular sieving properties of some of these materials, like zeolites. Porous electrodes also raise some difficulties for the analysis of their behaviour, due to internal diffusion/adsorption processes and high ohmic-drops. In this paper we have applied digital simulation to analyse the cyclic voltammetric behaviour of a zeolite/graphite composite electrode used in the electro-oxidation of phenolic compounds.

Carvalho, R. H.; Lemos, M. A. N. D. A.; Lemos, F.; Ramôa Ribeiro, F.

2007-12-01

170

Enzyme Electrode.  

National Technical Information Service (NTIS)

The patent application relates to an electrochemical device, and more particularly to an improved electrode structure for amperometric analysis of substances. Amperometric electrode sensors are known which include enzymes in their structure. Such devices ...

Guilbault

1973-01-01

171

Oxidation of anthracene on platinum macro- and micro-electrodes: Sonoelectrochemical, cryoelectrochemical and sonocryoelectrochemical studies.  

PubMed

The electro- and sonoelectro-chemical oxidation of anthracene in acetonitrile has been explored at room and low temperature (-40 degrees C) at a platinum micro- and macro-electrode, respectively. From both methodologies, the effective number of electrons, n(eff), in the oxidation process is evaluated at both room temperature and at the limit of the solvent-electrolyte freezing point. It is observed that n(eff) is close to 1 at low temperature while at room temperature it is higher, indicating sluggish follow up kinetics at lower temperature. The oxidative electrolysis of anthracene within an undivided cell, under various conditions is investigated with the product(s) obtained analysed and quantified by (1)H NMR. At room temperature under both 'silent' and 'sono' conditions the electrochemical oxidation produces 9,10-anthraquinone and bianthrone while at low temperature with acoustic streaming, anthracene-9,10-diol is additionally produced. Electrolyses with intentionally added water and also with oxygen saturation is investigated and its influence on the reaction pathway reported. In particular, the addition of water (1.4M) favours the formation of anthraquinone in a 3:1 ratio with bianthrone. Overall, the effect of lower temperature is to favour the formation of anthraquinone or its reduced form whilst the addition of insonation at low temperature is to substantially enhance the product yield per Coulomb of charge injected. PMID:16293520

Paddon, Christopher A; Banks, Craig E; Davies, Ieuan G; Compton, Richard G

2005-03-17

172

In situ STM studies of Sb(111) electrodes in aqueous electrolyte solutions  

NASA Astrophysics Data System (ADS)

The in situ STM studies of Sb(111), which was cleaved at the temperature of liquid nitrogen inside the glove box, and of Sb(111), which was electrochemically polished in the KI + HCl aqueous solution, have been performed under negative polarizations from - 0.8 to - 0.15 V (versus Ag|AgCl in sat. KCl aqueous solution) in the 0.5 M Na2SO4 + 0.0003 M H2SO4 aqueous solution. The atomic resolution has been achieved. The in situ STM data show that there are no quick surface reconstruction processes and the surface structure of cleaved and electrochemically polished Sb(111) is stable within the potential region investigated, similarly for Bi(111) single crystal electrode, previously studied [S. Kallip, E. Lust, Electrochem. Comm. 7 (2005) 863].

Grozovski, V.; Kallip, S.; Lust, E.

2013-07-01

173

Electrode compositions  

DOEpatents

An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

Block, J.; Fan, X.

1998-10-27

174

Electrode compositions  

DOEpatents

An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

Block, Jacob (Rockville, MD); Fan, Xiyun (Orange, TX)

1998-01-01

175

New Advances in the Study of the Proximal Point Algorithm  

NASA Astrophysics Data System (ADS)

Consider in a real Hilbert space H the inexact, Halpern-type, proximal point algorithm xn+1 = ?nu+(1-?n)J?nxn+en, n = 0,1,..., (H-PPA) where u, x?H are given points, J?n = (I+?na) for a given maximal monotone operator A, and (en) is the error sequence, under new assumptions on ?n?(0,1) and ?n?(0,1). Several strong convergence results for the H-PPA are presented under the general condition that the error sequence converges strongly to zero, thus improving the classical Rockafellar's summability condition on (||en||) that has been extensively used so far for different versions of the proximal point algorithm. Our results extend and improve some recent ones. These results can be applied to approximate minimizers of convex functionals. Convergence rate estimates are established for a sequence approximating the minimum value of such a functional.

Moro?anu, Gheorghe

2010-09-01

176

Hexafluorotantalate-selective electrode  

Microsoft Academic Search

The possibility has been shown of using tetraoctylammonium hexafluorotantalate as an electrode-active compound for a film-like (TaFâ)⁻-selective electrode. The influence of hydrofluoric and sulfuric acids on the electrode characteristic has been studied. The selectivity coefficients have been determined in 1 M HF solutions and in mixed fluoride-sulfate media. The possibility has been shown for the determination of the hexafluorotantalate ion

I. N. Semenova; A. F. Zhukov; O. M. Petrukhin

1986-01-01

177

Combined NMR and PDF studies of positive electrode materials for rechargeable lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Layered lithium nickel manganese oxides are promising, inexpensive and nontoxic alternative positive electrodes materials to the commercial LiCoO 2 electrode used in Li-ion batteries. Among these materials, Li(NiMn) 0.5O2 is particularly attractive due to its high theoretical capacity (280 mAh/g). The motivation for the research presented here was to understand the detailed long-range and short-range structure of these materials, particularly Li(NiMn)0.5O2, both as-synthesised and upon cycling. It is indeed important to know what the cation environments are, especially for the Li ions, since they strongly affect the electrochemical performance. The local environments and short-range ordering of Li(NiMn)0.5O 2, a potential Li-ion battery positive electrode material, were investigated by using a combination of X-ray and neutron diffraction and isotopic substitution (NDIS) techniques, 6Li Magic Angle Spinning (MAS) NMR spectroscopy and, for the first time, X-ray and neutron Pair Distribution Function (PDF) analysis, associated with Reverse Monte Carlo (RMC) calculations. Two Li(NiMn) 0.5O2 samples were studied in detail: one obtained from regular solid-state synthesis (SS), and another one obtained from ion-exchange routes (IE). 6Li MAS NMR experiments showed less Li/Ni site exchange (between the Li and the Ni/Mn layers) for the IE compound than for the SS compound, explaining its improved Li diffusivity and rate capability. For the SS compound, the Ni/Ni and Mn/Mn repulsion seen by PDF/RMC and the Li/Mn proximity seen by NMR were consistent with an ordering scheme intermediate between the ideal structures proposed so far (the "honey-comb" and "flower" structures). Ordering of Ni and Mn atoms in the transition metal layers was also detected in IE-Li(NiMn)0.5O2: Ni atoms tend to be surrounded by more Mn atoms in the first coordination shell, while the second coordination shell shows that zigzag ordering scheme is preferred over the chain. Ex-situ neutron diffraction and, for the first time on battery materials, in-situ X-ray PDF experiments were also performed to study the evolution of the cation arrangement during cycling. Based on this work, many applications of this joint NMR-PDF analysis approach to many battery systems may be readily envisaged.

Breger, Julien

178

Olivine electrode engineering impact on the electrochemical performance of lithium-ion batteries.  

SciTech Connect

High energy and power density lithium iron phosphate was studied for hybrid electric vehicle applications. This work addresses the effects of porosity in a composite electrode using a four-point probe resistivity analyzer, galvanostatic cycling, and electrochemical impedance spectroscopy (EIS). The four-point probe result indicates that the porosity of composite electrode affects the electronic conductivity significantly. This effect is also observed from the cell's pulse current discharge performance. Compared to the direct current (dc) methods used, the EIS data are more sensitive to electrode porosity, especially for electrodes with low porosity values.

Lu, W.; Jansen, A.; Dees, D.; Henriksen, G.; Chemical Sciences and Engineering Division

2010-08-01

179

Theoretical and experimental study on RF tumor ablation with internally cooled electrodes: when does the roll-off occur?  

PubMed

The Cool-tip is one of the most widely employed electrodes in radiofrequency (RF) ablation (RFA) of hepatic tumors. This electrode creates reliable geometry and coagulation zones. Despite the advantages of this electrode, during the ablation is produced a phenomenon called roll-off in which impedance increases, energy deposition completely stops and the lesion size cannot be increased. Consequently, the thermal lesion size is smaller and the tumors which can be ablated are smaller too. In this research we studied theoretical and experimentally the electrical-thermal performance of the Cool-tip electrode during RFA of hepatic tissue. Mainly, we were interested in the occurrence of the roll-off and its relationship with the tissue temperatures around the electrode. The theoretical model included the vaporization of the tissue and the variation of the thermal and electrical conductivities with temperature. The model was solved numerically using COMSOL Multiphysics software. For the experimental part we conducted a study in ex vivo liver tissue. The experimental and theoretical results showed that the roll-off is totally related when temperatures around 100 °C surrounds the tissue close to the center of the Cool-tip. The knowledge of this fact brings a powerful tool to analyze alternative methods or techniques to avoid the roll-off. PMID:22254312

Alba, J; González-Suárez, A; Trujillo, M; Berjano, E

2011-01-01

180

Nano-Ag-Nafion modified Pt electrode for oxidation of volatile organic compounds: an electrochemical study.  

PubMed

In this work, we describe Nano-Ag-Nafion coated pt electrode for oxidation of volatile organic compound (VOC), here acetaldehyde. Electrochemically synthesized Nano-Ag-Nafion film on Pt was analyzed by electrochemically in various electrolyte solutions like nitric acid, sulfuric acid, potassium nitrate, and potassium hydroxide for its stability. High stability of Nano-Ag-Nafion film appeared in potassium hydroxide medium among electrolyte solutions studied. Electrocatalysis of acetaldehyde was occurred only in acid and neutral medium. A catalytic oxidative peak during cathodic voltammetric reduction scan was observed at 1.75 V, which, unusual redox behavior, follows EC' reaction path way between electrogenerated Ag(II) and acetaldehyde. For Nano-Ag potential applicability, a calibration plot was drawn from various concentration range of acetaldehyde to check the maximum concentration level of acetaldehyde degradation in air. PMID:22103205

Muthuraman, G; Chung, Sang Joon; Moon, Il Shik

2011-08-01

181

Experimental Study of Two-frequency Dielectrophoresis Effects on a Linear Electrode Array.  

PubMed

Dielectrophoresis is a powerful tool for the manipulation of particles and biological cells. The magnitude and direction of the DEP force is determined by the comparative conductivity and permeability of the medium and the particle. Most previous work has focused on single frequency studies. In this paper, we present the work of two frequency dielectrophroesis effects on a linear electrode array. We show results where the advantage of applying two frequencies is to separate particles having similar dielectric properties. In addition, we report the first experimental data on breaking of DEP trapping zone by adding a low frequency signal to the main frequency signal. The phenomenon is due to a system disturbance by electro-hydrodynamic effect and has potential applications in DEP mixing and advanced control of particles. PMID:17282360

Zhang, Y; Bottausci, F; Macdonald, N; Mezic, I

2005-01-01

182

Vanadium pentoxide thin films used as positive electrode in lithium microbatteries: An XPS study during cycling  

NASA Astrophysics Data System (ADS)

Vanadium pentoxide thin films, usable as positive electrode in microbatteries, have been prepared by radio frequency magnetron sputtering in a pure argon or mixed argon/oxygen atmosphere using a V2O5 target. Depending on the oxygen partial pressure in the discharge gas, we have obtained either crystallized or amorphous thin films, with different morphologies. These two kinds of thin films having different electrochemical behavior, an extensive XPS study was carried out. The main redox processes and their reversibility occurring during the 1st, 10th, and 30th discharge charge cycles were discussed in relation with the electrochemical properties. Our results have revealed a good reversibility of the redox process for amorphous thin films and degradation for crystallized ones, in agreement with the discharge capacity evolution. Furthermore, the growth of a surface layer between the cathode and the liquid electrolyte was evidenced upon the discharge as well as its partial dissolution upon the charge.

Benayad, A.; Martinez, H.; Gies, A.; Pecquenard, B.; Levasseur, A.; Gonbeau, D.

2006-05-01

183

Cobalt (hydro)oxide electrodes under electrochemical conditions: a first principle study  

NASA Astrophysics Data System (ADS)

There is currently much interest in photoelectrochemical water splitting as a promising pathway towards sustainable energy production. A major issue of such photoelectrochemical devices is the limited efficiency of the anode, where the oxygen evolution reaction (OER) takes place. Cobalt (hydro)oxides, particularly Co3O4 and Co(OH)2, have emerged as promising candidates for use as OER anode materials. Interestingly, recent in-situ Raman spectroscopy studies have shown that Co3O4 electrodes undergo progressive oxidation and transform into oxyhydroxide, CoO(OH), under electrochemical working conditions. (Journal of the American Chemical Society 133, 5587 (2011))Using first principle electronic structure calculations, we provide insight into these findings by presenting results on the structural, thermodynamic, and electronic properties of cobalt oxide, hydroxide and oxydroxide CoO(OH), and on their relative stabilities when in contact with water under external voltage.

Chen, Jia; Selloni, Annabella

2013-03-01

184

The study of thermal processes in an electrode submitted to an electric arc  

Microsoft Academic Search

This article investigates the thermal phenomena that are occurring in an electrode submitted to an electric arc in air at atmospheric pressure. Our purpose is to get a better understanding of the electrode erosion phenomena concerning vaporization or liquid droplets ejection. For that we propose an original experimental device allowing the measurement of the liquid and vapor quantities created under

J. Devautour; J. P. Chabrerie; Ph. Testé

1993-01-01

185

The Variable Frame Theory of Focal Points: An Experimental Study  

Microsoft Academic Search

Invariable frame theorya game is played rationally, but which game gets played is determined by nonrational (e.g., perceptual) player characteristics. These determine their “frames”—the sets of attributes of the objects of choice they think about. The theory implies that it is rational to play focal points in coordination games with multiple equilibria. The reported experiment confirms most of the theory's

Michael Bacharach; Michele Bernasconi

1997-01-01

186

Topology Study of Photovoltaic Interface for Maximum Power Point Tracking  

Microsoft Academic Search

This paper looks at the performance of photovoltaic modules in nonideal conditions and proposes topologies to minimize the degradation of performance caused by these conditions. It is found that the peak power point of a module is significantly decreased due to only the slightest shading of the module, and that this effect is propagated through other nonshaded modules connected in

Weidong Xiao; Nathan Ozog; William G. Dunford

2007-01-01

187

Study Points to Acid Rain in Decline of Songbirds  

NSDL National Science Digital Library

New research from the Cornell Lab of Ornithology points to acid rain as a major cause of songbird decline, where previous research focused on forest fragmentation. This Web site is a brief article highlighting the research findings from the Atlanta Journal-Constitution, published on the Natural Resources Defense Council's Web page.

Seabrook, Charles.

2002-01-01

188

Games as Technological Entry Point: A Case Study of Uzbekistan  

Microsoft Academic Search

This paper considers cross-cultural patterns of game-playing activities. The paper is part of an overall argument regarding computer games as a possible technological entry point for novice users. In particular, increasing use of games in educational settings has drawn attention to the fact that computer games can be a way for young people to gain an initial exposure to computer

Beth E. Kolko; Alex Thayer

2003-01-01

189

REGIONAL AIR POLLUTION STUDY. POINT SOURCE EMISSION INVENTORY  

EPA Science Inventory

Emission data from stationary point sources in the St. Louis Interstate Air Quality Control Region were gathered during 1975. Data for 'criteria' pollutants were obtained on an hourly basis. Emissions from large sources were based on hourly, measured values at pertinent operating...

190

Electrode materials for lithium rechargeable batteries: Synthesis, spectroscopic studies and electrochemical performance  

NASA Astrophysics Data System (ADS)

The lithium rechargeable battery is the newest member of the rechargeable battery family and is best known for its high energy density, long battery life, low self-discharge rate and light weight. This battery may become one of the most important energy sources in consumer market, industrial and military applications. Intercalation compounds play a critical role in determining the overall performance of a lithium rechargeable battery. The common intercalation materials for battery applications are layered structure Lisb{x}CoOsb2, spinel Lisb{x}Mnsb2Osb4 and lithium vanadium oxides, Lisb{x}Vsb2Osb5 and Lisb{x}Vsb3Osb8. Three distinct Lisb{x}Vsb2Osb5 phases, delta,\\ varepsilon, and gamma-Lisb{x}Vsb2Osb5, were obtained through a chemical intercalation reaction and solid state reactions. Infrared and Raman spectra were recorded for the three phases. The spectral changes were interpreted in terms of the local structural changes of the vanadium-oxygen polyhedra. Although the delta and varepsilon phases have very similar powder x-ray diffraction patterns, IR and Raman studies showed these two phases adopt distinctive local structural environments. These results demonstrate that IR and Raman spectroscopy are important techniques for the structural analysis of intercalation materials. Single crystals of Lisb{1.1}Vsb3Osb8 and sp6Lisb{1.1}Vsb3Osb8 were prepared using solid state synthesis techniques. IR spectra and polarized Raman spectra were recorded on the Lisb{1.1}Vsb3Osb8 and sp6Lisb{1.1}Vsb3Osb8 crystals and a lithiated phase, Lisb4Vsb3Osb8. Factor group analysis method was used to interpret the spectral changes. These spectroscopic results provide insight into the structural modifications originating from lithium intercalation/deintercalation processes. In situ Raman spectra of Lisb{x}Vsb2Osb5 were successfully recorded on a operating lithium rechargeable battery. Distinctive spectral changes were observed at different lithium intercalation levels and interpreted in terms of the slight rearrangements of the V-O structural units. The results show that in situ Raman spectroscopy may become an important nondestructive technique in investigating the irreversible structural changes in electrode materials and evaluating battery performance. For the first time novel mesostructural materials were synthesized as electrode materials for the lithium rechargeable battery. The well-ordered mesostructural materials provide an ideal host for lithium transport processes. The preliminary results on the manganese oxide-based cathode and tin oxide-based anode show that the templating synthesis technique may provide important electrode materials for battery applications.

Zhang, Xulong

191

Application of the A.C. Admittance technique to double layer studies on polycrystalline gold electrodes  

NASA Astrophysics Data System (ADS)

A detailed examination of the dependence of the a.c. admittance of a cell containing a polycrystalline gold electrode has been made in the double layer region as a function of d.c. potential, a.c. frequency, and electrode history. It is shown that the interfacial impedance of a gold electrode with a carefully prepared surface can be treated under these circumstances as a constant phase element when it is in contact with an aqueous solution containing 0.05 M KClO4. Analysis of the frequency dependence of the cell impedance gives the surface inhomogeneity parameter n which turns out to be very close to unity. Although the electrode surface is only slightly inhomogeneous on a microscopic scale, a very large frequency dispersion of the impedance is observed experimentally. A method of estimating the true specific capacity of the electrode is presented, and conditions for carrying out the experiments in a reproducible manner are discussed.

Fawcett, W. R.; Kovacova, Zuzana; Motheo, Arthur J.; Foss, Colby A., Jr.

1992-02-01

192

Crosstalk Studies of In-Plane Switching Mode under Different Pixel- and Common-Electrode Configurations  

NASA Astrophysics Data System (ADS)

In thin-film-transistor liquid-crystal display (TFT-LCD), particularly pixel-electrode configuration of in-plane switching (IPS) mode, crosstalk caused by capacitive coupling between pixel electrodes and data lines could result in image degradation. We derived the capacitive coupling ratio (CCR) of the IPS cell and analyzed the CCR of three conventional TFT-IPS pixel- and common-electrode structures to quantify the crosstalk properties. The effect of coupling voltage on electro-optics characteristics has been investigated. Our results showed that a common electrode placed adjacent to the data line could shield capacitive coupling between the data line and the pixel electrodes, and reduce CCR from 13% to 2.4% and crosstalk intensity ratio (CIR) from 21.2% to 3.9%. We also report the common-overlapping-pixel structure that not only increases the aperture ratio by 1.28 times but also reduces CCR from 13% to 9.1%.

Lin, Jiunn-Shyong; Yang, Kei-Hsiung; Chen, Shu-Hsia

2004-04-01

193

Hexafluorotantalate-selective electrode  

SciTech Connect

The possibility has been shown of using tetraoctylammonium hexafluorotantalate as an electrode-active compound for a film-like (TaF/sub 6/)/sup -/-selective electrode. The influence of hydrofluoric and sulfuric acids on the electrode characteristic has been studied. The selectivity coefficients have been determined in 1 M HF solutions and in mixed fluoride-sulfate media. The possibility has been shown for the determination of the hexafluorotantalate ion using a (TaF/sub 6/)/sup -/-selective electrode in HF solutions, mixed fluoride-sulfate solutions, and also in the presence of niobium(V).

Semenova, I.N.; Zhukov, A.F.; Petrukhin, O.M.

1986-08-20

194

Dirac Fermions at the H Point of Graphite: Magnetotransmission Studies  

Microsoft Academic Search

We report on far infrared magnetotransmission measurements on a thin graphite sample prepared by exfoliation of highly oriented pyrolytic graphite. In a magnetic field, absorption lines exhibiting a blueshift proportional to B are observed. This is a fingerprint for massless Dirac holes at the H point in bulk graphite. The Fermi velocity is found to be ctilde =(1.02±0.02)×106m\\/s and the

M. Orlita; C. Faugeras; G. Martinez; D. K. Maude; M. L. Sadowski; M. Potemski

2008-01-01

195

Rotating ring disk electrode theory dealing with nonstationary electrocatalysis: Study of the electrocatalytic reduction of dioxygen at cobalt protoporphyrin modified electrode  

Microsoft Academic Search

An equation describing the variation of rate constant (k) with reaction charge (Q) and potential (E) for electrocatalysis is derived. A rotating ring disk electrode (RRDE) theory dealing with kinetic problems for dioxygen reduction at an unstable electrode is proposed. Using a rotation-scan RRDE method the kinetic behavior for the catalytic reduction of dioxygen at cobalt protoporphyrin modified pyrolytic graphite

Rongzhong. Jiang; Shaojun. Dong

1990-01-01

196

Laparoscopic implantation of neural electrodes on pelvic nerves: an experimental study on the obturator nerve in a chronic minipig model  

Microsoft Academic Search

Background  Laparoscopic exposure of pelvic nerves has opened a new area in the field of neuromodulation. However, electrode design and\\u000a material deterioration remain issues that limit clinical application. The objective of this study was to evaluate experimentally\\u000a the laparoscopic implantation of different types of neural electrodes in order to achieve functional and selective electrical\\u000a stimulation of pelvic nerves.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  This was a

Demetrio Larraín; Pierre Rabischong; Revaz Botchorishvili; Georges Fraisse; Stephane Gallego; Philippe Gaydier; Jean Michel Chardigny; Paul Avan

197

Study of Point Blast wave Instability in Numerical Experiment  

NASA Astrophysics Data System (ADS)

The detection of cases demonstrating an unstable evolution of the point blast wave in perfect gas was the problem actually formulated since 1980s when it was found with the help of self-similar approach to stability problem that for cases of gas specific ratio ? being less than 1.20 bllast wave became unstable: the Rayleigh-Taylor type instability showed up at the shock front (Ref.1-3). Later these results were confirmed in computer experiments when 2D hydrodynamic code was used. This code selected shock wave front and used the 1-st order Godunov scheme. In this paper we set ourselves the task of doing that using 3D hydrodynamic code. So we carry out computer simulation of blast wave using 3D Eulerian code TREK (Ref.5,6). The other objective of computation is to determine if the regime of perturbation evolution depends on the second (angular) number of spherical harmonic. The computation geometry is as follows: At t=0, the initial pressure is set constant in the centre region, and the pressure is equal to zero beyond this region. The central region presents a slightly perturbed sphere: the value of sphere radius has a small perturbation proportional to spherical harmonic (Legendre polynomial). The entire material is ideal gas with density being equal of unit and ? = 1.1- 1.2. The perturbations considered are of reasonably high harmonic polar numbers n: n=16 and higher. Computation results are as follows: We prove the perturbation amplitude increase in case of n=16 and ? < 1.2 i.e. we get the direct proof of blast wave instability in these cases. We prove also that the perturbations evolution mode converts to the self-similar pattern in a short time (i.e. when the shock front radius increased by 3-4 times) independently from initial conditions and further proceeds according to the self-similar theory. We prove that oscillations period of non-axially symmetric harmonics is equal to that of axially symmetric ones with the same polar number n. We prove also that these periods are equal to that in self-similar theory (Ref.1-3). The non linear stage of evolution of blast wave axially symmetric perturbations is also studied. The computation of raising perturbations evolution is continued until the formation of singularities and jets on the axis of symmetry and their turbulizations. 1. V.Ktitorov, Voprosy Atomnoi Nauki i Tekhniki, Ser.TPF, No2, p.28, (1984); 2. D.Ryu and E.T.Vishniac, Astr.J, 313, p.820 (1987); 3. V.Ktitorov, Khimich. Fizika (Chem Phys Issues) V.14, No 2-3, p.169, (1995); 4. V.Ktitorov, V.Meltzas, Proceedings of the 6th IWPTM, p.251-258. 5. A.Stadnik, V.Tarasov, Yu. Yanilkin, Voprosy Atomnoi Nauki i Tekhniki, Ser.MMFP, No3, p.52, (1995); 6. Yu.Yanilkin et al., Proceedings of the 6th IWPTM,. p.520-526.

Ktitorov, Vladimir; Yanilkin, Yurii

1999-06-01

198

Study of CO 2 electrodes in open devices of potentiometric sensors  

Microsoft Academic Search

Potentiometric CO2 sensors in open devices with NASICON as solid electrolyte were tested in the temperature range 150–500 °C and at partial pressures between 10?6 and 0.1 atm in air. The sensors were built with sodium titanate and La1?xSrXMnO3±? (LSM) mixtures as oxygen reference electrode and Na2CO3–BaCO3 or Na2CO3–SrCO3 mixed with gold as measuring electrodes. The CO2 electrode reaction is

Joel Ram??rez-Salgado; Pierre Fabry

2003-01-01

199

Studies on conducting polymer electroactive paper actuators: effect of humidity and electrode thickness  

NASA Astrophysics Data System (ADS)

Actuators based on cellulose paper with conducting polymer (CP-EAPap) as an electrode material were constructed. The bilayer and trilayer types of actuators were fabricated by depositing conducting polypyrrole on one side and two sides of cellophane paper respectively, which was previously gold coated. By varying the deposition time, the electrode thickness was manipulated. The performance of these two types of actuators was compared with respect to humidity changes and thickness variation. The electrode thickness plays a key role in the displacement behavior of these types of actuators. The best performance at higher humidity is also characteristic of CP-EAPap actuators. The possible mechanism of actuation is addressed in this paper.

Deshpande, S. D.; Kim, Jaehwan; Yun, Sung-Ryul

2005-08-01

200

Monochromatic imaging studies of sustained metal vapor arcs burning on 150 mm diameter molten iron electrodes  

SciTech Connect

Monochromatic imaging was used to investigate the excited-state density distributions of Fe and Fe{sup +} in the inter-electrode gap region of a 3,100 A dc metal vapor arc burning between molten iron surfaces in a vacuum arc furnace. Multiple images were acquired at four wavelengths. The images were corrected and Abel inverted to yield the absolute radial intensity distributions for Fe and Fe{sup +} in the inter-electrode gap region. The results show a structured, axisymmetric plasma consisting of a high density `core` of Fe{sup +} emitters centered between the electrode surfaces situated against a relatively broad, flat excited-state Fe distribution.

Williamson, R.L.; Schlienger, M.E.

1996-07-01

201

Numerical Studies and Equipment Development for Single Point Incremental Forming  

NASA Astrophysics Data System (ADS)

This paper summarizes the achievements obtained so far in the context of a research project carried out at the University of Aveiro, Portugal on both numerical and experimental viewpoints concerning Single Point Incremental Forming (SPIF). On the experimental side, the general guidelines on the development of a new SPIF machine are detailed. The innovation features are related to the choice of a six-degrees-of-freedom, parallel kinematics machine, with a high payload, to broad the range of materials to be tested, and allowing for a higher flexibility on tool-path generation. On the numerical side, preliminary results on simulation of SPIF processes resorting to an innovative solid-shell finite element are presented. The final target is an accurate and fast simulation of SPIF processes by means of numerical methods. Accuracy is obtained through the use of a finite element accounting for three-dimensional stress and strain fields. The developed formulation allows for an unlimited number of integration points through its thickness direction, which promotes accuracy without loss of CPU efficiency. Preliminary results and designs are shown and discussions over the obtained solutions are provided in order to further improve the research framework.

Marabuto, S. R.; Sena, J. I. V.; Afonso, D.; Martins, M. A. B. E.; Coelho, R. M.; Ferreira, J. A. F.; Valente, R. A. F.; de Sousa, R. J. Alves

2011-05-01

202

Durability study of electrospray deposited Pt film electrode for hydrogen production in PV assisted water electrolysis system  

Microsoft Academic Search

We studied the durability of the previously reported low mass loaded, highly efficient electrospray deposited Pt film as a cathode and Ni mesh as anode electrode in PV assisted water electrolysis system for 1000 h. This assembly showed no detectable decline in performance for initial 200 h, but thereafter it started to decline with time and showed 18% decline after 1000 h. For

Sang-Youn Chae; Jyotiprakash B. Yadav; Kang-Jin Kim; Oh-Shim Joo

2011-01-01

203

In situ UV–Vis spectroscopic study of the electrocatalytic oxidation of hypophosphite on a nickel electrode  

Microsoft Academic Search

The electrocatalytic oxidation of hypophosphite on a nickel electrode has been studied by means of in situ UV–Vis subtractive reflectance spectroscopy to obtain information about the anodic oxidation mechanism. An absorbency band around 245 nm, which was ascribed to the formation of an intermediate, ?·PHO?2, was observed in the electrocatalytic oxidation process. Accordingly, the electrocatalytic oxidation of hypophosphite might undergo

Yue Zeng; Shaomin Zhou

1999-01-01

204

An electrode array study of electrochemical inhomogeneity of zinc in zinc\\/steel couple during galvanic corrosion  

Microsoft Academic Search

The local electrochemical properties of anodic metal within a zinc\\/steel couple immersed in seawater was studied via an electrode array composed of zinc and mild steel wire sensors. It showed that the potential and current density distribution of zinc wires were inhomogeneous, and the main anodic area moved from the zinc wires adjacent to the steel wires and even further

Da-Lei Zhang; Wei Wang; Yan Li

2010-01-01

205

Voltammetric study and electrochemical detection of hexavalent chromium at gold nanoparticle-electrodeposited indium tinoxide (ITO) electrodes in acidic media.  

PubMed

The voltammetric behavior of hexavalent chromium species (Cr(VI)) was respectively studied at ITO, bulk Au, and Au-electrodeposited electrodes in 0.01 M NaCl aqueous solutions containing 0.01 M HCl. It was found that performance degradation of the ITO electrodes toward the reduction of Cr(VI) can be suppressed by modifying the electrode surface with gold nanoparticles (AuNPs), which were formed on ITO electrodes by potential-sweeping or potential-step electrodeposition in a 0.01 M Na(2)SO(4) solution containing 1 mM HAuCl(4) x 3 H(2)O and 0.01 M H(2)SO(4). After the modification, the surface of ITO electrodes turned to the characteristically red or blue color exhibited by AuNPs. The gold nanoparticle-electrodeposited indium-tinoxide electrode (AuNP-ITO) demonstrates unique catalytic behavior, higher sensitivity and stability in the reduction of Cr(VI). Cr(VI) species was detected by either cyclic voltammetry or hydrodynamic amperometry. By cyclic voltammetry, the dependence of cathodic peak current on concentration was linear from 5 to 100 microM with a detection limit of 2 microM (sigma=3), and linearity was obtained from 0.5 to 50 microM by hydrodynamic amperometry where a constant potential of +0.2V (vs. Ag/AgCl) was applied and a batch-injection cell was employed. For hydrodynamic amperometry, the detection limit was 0.1 microM (sigma=3). PMID:18585318

Tsai, Ming-Chih; Chen, Po-Yu

2008-04-04

206

A comparative study of synthetic graphite and Li electrodes in electrolyte solutions based on ethylene carbonate-dimethyl carbonate mixtures  

SciTech Connect

This work entails a comparative study of both Li and synthetic graphite electrodes in electrolyte solutions based on ethylene and dimethyl carbonates (EC-DMC) and the impact of the salt used [from the LiAsF{sub 6}, LiClO{sub 4}, LiPF{sub 6}, LiBF{sub 4}, and LiN(SO{sub 2}CF{sub 3}){sub 2} list]. The presence of some additives in solutions (e.g., Li{sub 2}CO{sub 3}, CO{sub 2}, tributylamine) and the effect of the particle size of the carbon on the electrode`s behavior were investigated. The correlation between the surface chemistry, the morphology, and the performance of Li and graphite electrodes was explored using surface sensitive Fourier transform infrared and X-ray and photoelectron spectroscopies, impedance spectroscopy, X-ray diffraction and scanning electron microscopy in conjunction with standard electrochemical techniques. Synthetic graphite anodes could be cycled (Li intercalation-deintercalation) hundreds of times at a capacity close to the optimal (x = 1 in Li{sub x}C{sub 6}) in C-DMC solutions due to the formation of highly stable and passivating surface films in which EC reduction products such as (CH{sub 2}OCO{sub 2}Li){sub 2} are the major constituents. The cycling efficiency of Li metal anodes in these solutions, however, is lower than that obtained in ethereal solutions and seems to be too low for Li-metal liquid electrolyte, rechargeable battery application. The connection between the solution composition and the electrode`s performance is discussed.

Aurbach, D.; Markovsky, B.; Schechter, A.; Ein-Eli, Y. [Bar-Ilan Univ., Ramat Gan (Israel). Dept. of Chemistry; Cohen, H. [Weizmann Inst. of Science, Rehovoth (Israel). Chemical Service Unit

1996-12-01

207

Electronic and Photoelectron Spectral Studies of Electroactive Species Attached to Silanized C and Pt Electrodes.  

National Technical Information Service (NTIS)

Depending on silanization reaction conditions, aminophenylferrocene and tetrakis (p-aminophenyl) porphyrin can be covalently attached in monolayer or multi-molecular layer quantities to glassy carbon and superficially oxidized Pt electrodes using 4-(methy...

K. W. Willman R. D. Rocklin R. Nowak K. N. Kuo F. A. Schultz

1980-01-01

208

Simulation studies of bus electrode effect on discharge and luminous characteristics of plasma display panels  

SciTech Connect

We have investigated how bus electrodes affect discharge and luminous characteristics of a discharge cell. Three-dimensional simulations have been performed in a coplanar structured alternating current plasma display panel cell, with phosphor saturation effect taken into account. There exists the optimal position of bus electrodes for high luminance and luminous efficiency. Considering bus electrode thickness, we have found that in-bus structure is a promising candidate for high luminance, high luminous efficiency, and fast operation plasma display panels. Our simulation results would be very useful to understand the influence of bus electrode on characteristics of a plasma display panel cell, and would also provide a general guidance to improve its display performances.

Lee, Insook; Choi, K.Y. [Digital Display Research Laboratory, LG Electronics Inc., 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724 (Korea, Republic of)

2005-03-01

209

Carbon Paste Electrodes Made from Different Carbonaceous Materials: Application in the Study of Antioxidants  

PubMed Central

This work describes the sensing properties of carbon paste electrodes (CPEs) prepared from three different types of carbonaceous materials: graphite, carbon microspheres and carbon nanotubes. The electrochemical responses towards antioxidants including vanillic acid, catechol, gallic acid, l-ascorbic acid and l-glutathione have been analyzed and compared. It has been demonstrated that the electrodes based on carbon microspheres show the best performances in terms of kinetics and stability, whereas G-CPEs presented the smallest detection limit for all the antioxidants analyzed. An array of electrodes has been constructed using the three types of electrodes. As demonstrated by means of Principal Component Analysis, the system is able to discriminate among antioxidants as a function of their chemical structure and reactivity.

Apetrei, Constantin; Apetrei, Irina Mirela; De Saja, Jose Antonio; Rodriguez-Mendez, Maria Luz

2011-01-01

210

Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode.  

National Technical Information Service (NTIS)

Quantitative measurement of adsorption/desorption of oxalic acid on a platinum (Pt) electrode from a perchloric acid supporting electrolyte has been accomplished for the first time using a fast potential scan preceded by a sequence of potential steps. Fro...

S. Gilman

2012-01-01

211

An impedance study of complex Al/Cu-Al2O3 electrode  

NASA Astrophysics Data System (ADS)

Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on Al surfaces by internal electrolysis.

Denisova, J.; Katkevics, J.; Erts, D.; Viksna, A.

2011-06-01

212

Basic Study of Sorption of Organic Fuels During Oxidation at Electrodes.  

National Technical Information Service (NTIS)

The objective of this program was an improved understanding of the role of sorption processes at electrodes in the electrochemical oxidation of carbonaceous fuels with special emphasis on the development of novel experimental approaches to this end. Of th...

R. J. Flannery G. Aronowitz E. M. Banas M. J. Den Herder J. A. Donohue

1964-01-01

213

Contribution to the Study of the Electric Arc: Erosion of Metallic Electrodes.  

National Technical Information Service (NTIS)

A procedure is described for determining the extent of arc electrode erosion (excluding erosion due to transfer of material) from measurements of emitted spectral beam intensity. The relation between emission intensity and plasma temperature is ascertaine...

A. Castro

1986-01-01

214

Studies of LaSn{sub 3} as a negative electrode for lithium ion batteries.  

SciTech Connect

The intermetallic compound LaSn{sub 3} has been explored as a possible negative electrode for lithium-ion batteries. A combination of experiment and density functional theory calculations provides evidence that the structure is intolerant to lithium insertion and that the electrochemical reaction occurs via a displacement mechanism. Experiment shows that approximately six Li react initially with LaSn{sub 3}; calculated energetics suggest that during the reaction La{sub 3}Sn{sub 5} and lithiated tin are formed and that the electrode operates by delithiation and relithiation of the Sn particles within an inert lanthanum-tin matrix. LaSn{sub 3} electrodes provide a reversible specific capacity of 200-250 mAh/g, whereas In-substituted electrodes that form a solid solution with LaSn{sub 3}, such as LaSn{sub 2.7}In{sub 0.3}, yield a slightly lower capacity.

Vaughey, J. T.; Thackeray, M. M.; Shin, D.; Wolverton, C.; Northwestern Univ.

2009-01-01

215

Characterization and electrochemical studies of Nafion\\/nano-TiO 2 film modified electrodes  

Microsoft Academic Search

A nano-TiO2 film from stable aqueous dispersion has been modified on a glassy carbon electrode (GCE), and was characterized by scanning electron microscopy (SEM) and surface-enhanced Raman spectroscopy (SERS). This nanostructured film exhibits an ability to improve the electron-transfer rate between electrode and dopamine (DA), and electrocatalyze the redox of DA. The electrocatalytical behavior of DA was examined by cyclic

Shuai Yuan; Shengshui Hu

2004-01-01

216

Reference Electrodes  

NASA Astrophysics Data System (ADS)

In most electrochemical measurements, it is necessary to keep one of the electrodes in an electrochemical cell at a constant potential. This so-called reference electrode allows control of the potential of a working electrode (e.g. in voltammetry) or the measurement of an indicator electrode (e.g. in potentiometry, see Chap. II.9). The standard hydrogen electrode plays the role of a basic reference element in electrochemical devices; however, in practice, it is difficult to handle. Therefore, secondary reference electrodes are preferred in most experiments. A secondary reference electrode must fulfil the following criteria: (i) it should be chemically and electrochemically reversible, i.e. its potential is governed by the Nernst equation and does not change in time; (ii) the potential must remain almost constant when a small current passes through the electrode and reverse to its original value after such small current flow (i.e. a non-polarisable electrode); and (iii) the thermal coefficient of potential should be small.

Kahlert, Heike

217

Finite element modeling of electrode-skin contact impedance in electrical impedance tomography.  

PubMed

In electrical impedance tomography (EIT), we inject currents through and measure voltages from an array of surface electrodes. The measured voltages are sensitive to electrode-skin contact impedance because the contact impedance and the current density through this contact impedance are both high. We used large electrodes to provide a more uniform current distribution and reduce the contact impedance. A large electrode differs from a point electrode in that it has shunting and edge effects which cannot be modeled by a single resistor. We used the finite element method (FEM) to study the electric field distributions underneath an electrode, and developed three models: a FEM model, a simplified FEM model and a weighted load model. We showed that the FEM models considered both shunting and edge effects and matched closely the experimental measurements. FEM models for electrodes can be used to improve the performance of an electrical impedance tomography reconstruction algorithm. PMID:8375870

Hua, P; Woo, E J; Webster, J G; Tompkins, W J

1993-04-01

218

Solid state NMR and pair distribution function studies of silicon electrodes for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

The universally used negative electrode material in a LIB is carbon, because of its moderate capacity (372 mAhg-1 for graphite), cyclability and high rate capability. However, new, low cost, safe electrode materials with higher capacities are still urgently required for both portable and transportation applications. Silicon anodes are particularly attractive alternatives to carbon with extremely high gravimetric energy densities (3572 mAhg-1). Compared to graphite, silicon has a massive volumetric capacity of 8322 mAhcm-3 (calculated based on the original volume of silicon) which is approximately ten times that graphite. At room temperature, upon electrochemical lithiation, silicon undergoes a crystalline to amorphous phase transition forming a lithiated amorphous silicide phase. Unfortunately, due to the amorphous nature of the lithiated silicides, it is not possible to monitor all the structural changes that occur during lithium insertion/removal with conventional methods such as diffraction. The short range order of the amorphous materials remains unknown, preventing attempts to optimize performance based on electrochemical-structure correlations. In this work, a combination of local structure probes, ex-situ 7Li nuclear magnetic resonance (NMR) studies and pair distribution function (PDF) analysis of X-ray data was applied to investigate the changes in short range order that occur during the initial charge and discharge cycles. The distinct electrochemical profiles observed subsequent to the 1 st discharge have been shown to be associated with the formation of distinct amorphous lithiated silicide structures. A (de)lithiation model consisting of four different mechanisms, each being valid for regions of the charge or discharge process is proposed to explain the hysteresis and the steps in the electrochemical profile observed during lithiation and delithiation of Si. A spontaneous reaction of the fully lithiated lithium silicide with the electrolyte is directly observed in the in situ NMR experiments; this mechanism results in self-discharge, and potentially capacity loss. The rate of this self-discharge process is much slower when CMC (carboxymethylcellulose) is used as the binder. Previous work has shown that the electrochemical performance of nanoparticulate crystalline silicon is different from the bulk. The lithiation and delithiation mechanisms of nano-Si for lithium ion batteries are studied by using ex-situ solid state MAS NMR and PDF analysis. The main differences vs. bulk lithiation and delithiation are identified by characterizing the amorphous phases formed.

Key, Baris

219

Surface-enhanced Raman spectroscopy of surfactants on silver electrodes  

SciTech Connect

Surface-enhanced Raman spectroscopy (SERS) has been used to study different kinds of surfactants (cationic, anionic, and nonionic surfactants) adsorbed on a roughened Ag electrode. Spectral assignments are made for the SERS spectrum of cetylpyridinium chloride (CPC), and it is shown that the molecule is oriented with its pyridinium ring end-on at the electrode surface at potentials positive to the point of zero charge (pzc) on Ag.

Sun, Soncheng; Birke, R.L.; Lombardi, J.R. (City Univ. of New York, NY (USA))

1990-03-08

220

Single Camera Photogrammetry System for EEG Electrode Identification and Localization  

Microsoft Academic Search

In this study, photogrammetric coordinate measurement and color-based identification of EEG electrode positions on the human\\u000a head are simultaneously implemented. A rotating, 2MP digital camera about 20 cm above the subject’s head is used and the images\\u000a are acquired at predefined stop points separated azimuthally at equal angular displacements. In order to realize full automation,\\u000a the electrodes have been labeled by

U?ur Baysal; Gökhan ?engül

2010-01-01

221

Empirical study of unipolar and bipolar configurations using high resolution single multi-walled carbon nanotube electrodes for electrophysiological probing of electrically excitable cells  

NASA Astrophysics Data System (ADS)

Identifying the neurophysiological basis underlying learning and memory in the mammalian central nervous system requires the development of biocompatible, high resolution, low electrode impedance electrophysiological probes; however, physically, electrode impedance will always be finite and, at times, large. Herein, we demonstrate through experiments performed on frog sartorius muscle that single multi-walled carbon nanotube electrode (sMWNT electrode) geometry and placement are two degrees of freedom that can improve biocompatibility of the probe and counteract the detrimental effects of MWNT/electrolyte interface impedance on the stimulation efficiency and signal-to-noise ratio (SNR). We show that high aspect ratio dependent electric field enhancement at the MWNT tip can boost stimulation efficiency. Derivation of the sMWNT electrode's electrical equivalent indicates that, at low stimulus voltage regimes below 1 V, current conduction is mediated by charge fluctuation in the double layer obviating electrolysis of water, which is potentially toxic to pH sensitive biological tissue. Despite the accompanying increase in electrode impedance, a pair of closely spaced sMWNT electrodes in a two probe (bipolar) configuration maintains biocompatibility and enhances stimulation efficiency and SNR compared to the single probe (unipolar) configuration. For stimulus voltages below 1 V, the electrical equivalent verifies that current conduction in the two probe configuration still proceeds via charge fluctuation in the double layer. As an extracellular stimulation electrode, the two sMWNT electrodes comprise a current dipole that concentrates the electric field and the current density in a smaller region of sartorius; consequently, the bipolar configuration can elicit muscle fiber twitching at low voltages that preclude electrolysis of water. When recording field potentials, the bipolar configuration subtracts the potential between two points allowing for the detection of higher signal amplitudes. As a result, SNR is improved. These results indicate that use of the high aspect ratio MWNT in a bipolar configuration can achieve a biocompatible electrode that offers enhanced stimulation efficiency and higher SNR.

de Asis, Edward D., Jr.; Leung, Joseph; Wood, Sally; Nguyen, Cattien V.

2010-03-01

222

Empirical study of unipolar and bipolar configurations using high resolution single multi-walled carbon nanotube electrodes for electrophysiological probing of electrically excitable cells.  

PubMed

Identifying the neurophysiological basis underlying learning and memory in the mammalian central nervous system requires the development of biocompatible, high resolution, low electrode impedance electrophysiological probes; however, physically, electrode impedance will always be finite and, at times, large. Herein, we demonstrate through experiments performed on frog sartorius muscle that single multi-walled carbon nanotube electrode (sMWNT electrode) geometry and placement are two degrees of freedom that can improve biocompatibility of the probe and counteract the detrimental effects of MWNT/electrolyte interface impedance on the stimulation efficiency and signal-to-noise ratio (SNR). We show that high aspect ratio dependent electric field enhancement at the MWNT tip can boost stimulation efficiency. Derivation of the sMWNT electrode's electrical equivalent indicates that, at low stimulus voltage regimes below 1 V, current conduction is mediated by charge fluctuation in the double layer obviating electrolysis of water, which is potentially toxic to pH sensitive biological tissue. Despite the accompanying increase in electrode impedance, a pair of closely spaced sMWNT electrodes in a two probe (bipolar) configuration maintains biocompatibility and enhances stimulation efficiency and SNR compared to the single probe (unipolar) configuration. For stimulus voltages below 1 V, the electrical equivalent verifies that current conduction in the two probe configuration still proceeds via charge fluctuation in the double layer. As an extracellular stimulation electrode, the two sMWNT electrodes comprise a current dipole that concentrates the electric field and the current density in a smaller region of sartorius; consequently, the bipolar configuration can elicit muscle fiber twitching at low voltages that preclude electrolysis of water. When recording field potentials, the bipolar configuration subtracts the potential between two points allowing for the detection of higher signal amplitudes. As a result, SNR is improved. These results indicate that use of the high aspect ratio MWNT in a bipolar configuration can achieve a biocompatible electrode that offers enhanced stimulation efficiency and higher SNR. PMID:20182008

de Asis, Edward D; Leung, Joseph; Wood, Sally; Nguyen, Cattien V

2010-02-25

223

Potential Distribution About an Electrode on the Surface of the Earth  

Microsoft Academic Search

An analytical study is made of the potential distribution about an electrode on a stratified earth, from the point of view of developing special formulas appropriate for computation at small and large distances from the electrode. Power series in the distance for small distances and simple asymptotic expansions for large separations are derived first for a two layer earth, from

Morris Muskat

1933-01-01

224

Ionization EM calorimetry with accordion electrodes and liquid krypton or argon  

SciTech Connect

The results of a study and tests of a liquid krypton/argon electromagnetic calorimeter with accordion electrode structure are briefly summarized. This includes the calorimeter response to electrons and muons, energy, pointing and timing resolution, and a measurement by multiple sampling. The electrode layout with fine segmentation is illustrated.

Radeka, V.

1993-11-01

225

Feasibility of gait training for acute stroke patients using FNS with implanted electrodes  

Microsoft Academic Search

Following stroke, many patients do not regain a normal, safe gait pattern even after receiving conventional physical therapy. One promising technique is functional neuromuscular stimulation (FNS) with intramuscular (IM) electrodes (FNS-IM). Five subjects were admitted into the study at 3 weeks to 3 months following the stroke. For each subject, electrodes were placed intramuscularly at the motor point of up

Janis J Daly; Robert L Ruff; Kathryn Haycook; Beth Strasshofer; E. Byron Marsolais; Loreen Dobos

2000-01-01

226

Conversion Reaction Mechanisms in Lithium Ion Batteries: Study of the Binary Metal Fluoride Electrodes  

SciTech Connect

Materials that undergo a conversion reaction with lithium (e.g., metal fluorides MF{sub 2}: M = Fe, Cu, ...) often accommodate more than one Li atom per transition-metal cation, and are promising candidates for high-capacity cathodes for lithium ion batteries. However, little is known about the mechanisms involved in the conversion process, the origins of the large polarization during electrochemical cycling, and why some materials are reversible (e.g., FeF{sub 2}) while others are not (e.g., CuF{sub 2}). In this study, we investigated the conversion reaction of binary metal fluorides, FeF{sub 2} and CuF{sub 2}, using a series of local and bulk probes to better understand the mechanisms underlying their contrasting electrochemical behavior. X-ray pair-distribution-function and magnetization measurements were used to determine changes in short-range ordering, particle size and microstructure, while high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) were used to measure the atomic-level structure of individual particles and map the phase distribution in the initial and fully lithiated electrodes. Both FeF{sub 2} and CuF{sub 2} react with lithium via a direct conversion process with no intercalation step, but there are differences in the conversion process and final phase distribution. During the reaction of Li{sup +} with FeF{sub 2}, small metallic iron nanoparticles (<5 nm in diameter) nucleate in close proximity to the converted LiF phase, as a result of the low diffusivity of iron. The iron nanoparticles are interconnected and form a bicontinuous network, which provides a pathway for local electron transport through the insulating LiF phase. In addition, the massive interface formed between nanoscale solid phases provides a pathway for ionic transport during the conversion process. These results offer the first experimental evidence explaining the origins of the high lithium reversibility in FeF{sub 2}. In contrast to FeF{sub 2}, no continuous Cu network was observed in the lithiated CuF{sub 2}; rather, the converted Cu segregates to large particles (5-12 nm in diameter) during the first discharge, which may be partially responsible for the lack of reversibility in the CuF{sub 2} electrode.

Wang, Feng; Robert, Rosa; Chernova, Natasha A.; Pereira, Nathalie; Omenya, Fredrick; Badway, Fadwa; Hua, Xiao; Ruotolo, Michael; Zhang, Ruigang; Wu, Lijun; Volkov, Vyacheslav; Su, Dong; Key, Baris; Whittingham, M. Stanley; Grey, Clare P.; Amatucci, Glenn G.; Zhu, Yimei; Graetz, Jason (Rutgers); (SBU); (Cambridge); (SUNY-Binghamton); (BNL)

2012-03-15

227

A mortality cohort study among workers in a graphite electrode production plant in Italy  

PubMed Central

Aims: To investigate mortality from cancer and other diseases among workers in a graphite electrode production plant in Italy. Methods: A total of 1291 males actively employed between 1 January 1950 and 31 December 1989 who had worked at the plant for at least one year were studied. The follow up extended from 1950 to 1997. Standardised mortality ratios (SMR) and their 95% confidence intervals (CI) were computed using mortality rates for the Italian and regional male population. Results: Excess mortality was observed for all causes (SMR 1.44, CI 1.32 to 1.56), all cancers (SMR 1.27, CI 1.07 to 1.50), liver cancer (SMR 4.19, CI 2.68 to 6.23), silicosis (SMR 66.39, CI 52.56 to 82.7), and cirrhosis and other chronic diseases of the liver (SMR 1.87, CI 1.31 to 2.59) in comparison with the national male population. When regional rates were used to calculate the number of expected deaths, SMRs remained higher for silicosis (SMR 57.32, 42.11 to 76.22), and liver cancer (SMR 2.57, 1.57 to 3.97). Mortality from silicosis was increased in workers hired at young ages (<25 years, SMR 81.79; 25–34 years, SMR 82.73), and in workers aged <45 at death (SMR 333.3, CI 159.8 to 613). Mortality from liver cancer increased threefold (SMR 3.11, CI 1.78 to 5.05) in workers with more than 10 years of employment at the plant during the manufacture of Karbate products. Conclusions: Results support the association between excess mortality from silicosis and occupational exposure to siliceous sands experienced during graphite electrode manufacturing. The observed excess mortality from liver cancer is compatible, to some extent, with exposures that may have occurred during the manufacture of phenolic and furfuryl resins treated products, although a role of lifestyle factors and viral infections cannot be excluded.

Merlo, D; Garattini, S; Gelatti, U; Simonati, C; Covolo, L; Ceppi, M; Donato, F

2004-01-01

228

Advanced electrodes for AMTEC  

NASA Astrophysics Data System (ADS)

Texas A&M University has begun an investigation of materials and fabrication methods which will improve AMTEC electrode performance. The study currently involves gathering data on materials which meet the basic requirements of operating in an AMTEC cell, and sorting out candidates possessing characteristics conducive to efficient AMTEC operation. An initial assessment has shown Iridium as a promising metal electrode candidate. Sodium-containing double-oxides, with melting temperatures above AMTEC operating temperatures, including NaNbO3 and Na2Ti3O7, have been identified as possible electrode dopants, to enhance the sodium conductivity of an electrode. Photo-deposition and Evaporative-deposition will be investigated further as electrode fabrication techniques.

Fiebig, Brad; Schuller, Michael; Ryan, Margaret Amy; Williams, Roger; Hudson, Patricia

1999-01-01

229

Investigation and Design Studies of SOFC Electrode Performance at Elevated Pressure  

SciTech Connect

An experimental program was set forth to study fuel cell performance at pressure and under various compositions. Improvement in cathode electrode performance is on the order of 33-40% at pressures of 6.4 Bara compared to atmospheric pressure. Key cathode operational parameters are the concentration and partial pressure of O2, and temperature. The effect of partial pressure of oxygen (PO2) decreases the activation polarization, although there appears to be a secondary effect of absolute pressure as well. The concentration of oxygen impacts the diffusion component of the polarization, which is largely insensitive to absolute pressure. The effect of pressure was found to reduce the total polarization resistance of full fuel-cells beyond the reduction determined for the cathode alone. The total reduction in ASR was on the order of 0.10 ohm-cm2 for a pressure increase from 1 to 6.5 Bara, with about 70% of the improvement being realized from 1 to 4 Bara. An important finding was that there is an effect of steam on the cathode that is highly temperature dependent. The loss of performance at temperatures below 850 C was very large for the standard LSM + YSZ cathodes.

Ted Ohrn; Shung Ik Lee

2010-07-31

230

Spectroelectrochemical studies on dissolution and passivation of zinc electrodes in alkaline solutions  

SciTech Connect

Electrochemical oxidation of zinc electrodes has been studied in 1.0 M KOH solutions employing cyclic voltammetric and in situ spectroelectrochemical techniques. The results indicate that three different processes, i.e., dissolution, prepassivation, and passivation, take place in different potential regions. Two optically different solution species absorbing at 250 and 290 nm, which are assigned to Zn(OH){sub 4}{sup 2{sup {minus}} and Zn(OH){sub 3}{sup minus}}, respectively, are produced initially during anodic oxidation of zinc at different potentials to different extents with different respective ratios. These species undergo a series of consecutive chemical reactions to eventually lead to passive films on the surface. The film compositions were identified to be ZnO{sub 1{minus}x}(OH){sub 2x}OH{sup {minus}}-doped ZnO, and Zn-doped ZnO depending on the potential regime and aging. Details of the electrochemistry and chemistry taking place during electrolysis in these three regions are discussed based on the cyclic voltammetric and spectroelectrochemical data.

Cai, M.; Park, S.M. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemistry

1996-07-01

231

Tunnel magnetoresistance effect and interface study in magnetic tunnel junctions using epitaxial Fe2CrSi Heusler alloy electrode  

NASA Astrophysics Data System (ADS)

We report the studies of magnetic tunnel junctions (MTJs) using epitaxially grown Fe2CrSi (FCS) as a bottom electrode. A tunnel magnetoresistance (TMR) ratio of 2.5% was obtained for MTJ at room temperature. The low TMR ratio is attributed to the oxidation of FCS at the interface with MgO barrier. With the insertion of 0.3 nm Mg layer between the FCS and MgO barrier layers, the TMR ratio increases to 8.1%. X-ray Photoelectron Spectroscopy results show that the FCS film is most likely terminated at Fe and Si atomic layers, which is found to be bonded to oxygen at the interface, while Cr remains at metallic state. Post-annealing effect shows that TMR first increases with annealing temperature (Ta) due to improvement in crystalline structure of MgO and top electrode and then decreases due to oxidation of the bottom electrode. The TMR finally disappears due to the depinning of top electrode induced by Mn diffusion at high Ta.

Wang, Yu-Pu; Han, Gu-Chang; Lu, Hui; Qiu, Jinjun; Yap, Qi-Jia; Ji, Rong; Teo, Kie-Leong

2013-07-01

232

The study of thermal processes in an electrode submitted to an electric arc  

NASA Astrophysics Data System (ADS)

This article investigates the thermal phenomena that are occurring in an electrode submitted to an electric arc in air at atmospheric pressure. Our purpose is to get a better understanding of the electrode erosion phenomena concerning vaporization or liquid droplets ejection. For that we propose an original experimental device allowing the measurement of the liquid and vapor quantities created under the arc root. The principle of this device is based on the ejection of the liquid metal through centrifugal movement of the electrodes during the arc. Some results are given relatively to Ag, Cu and AgSnO2 cathodes and anodes. Then we present a numerical modelling of the thermal phenomena induced in the electrode by the heat transferred from the arc root. We propose a method to solve the difficulties related to this kind of “free boundary” problems induced by the fact that the electrode material may undergo various phase changes. Finally we show how to use this numerical computation and the experimental results in order to estimate the power density input at a copper anode.

Devautour, J.; Chabrerie, J. P.; Testé, Ph.

1993-06-01

233

Theoretical and experimental studies of the electrochemistry of p-aminophenol on a golden electrode  

NASA Astrophysics Data System (ADS)

The geometric parameters, vibrational frequencies, and thermochemical values of p-quinonimine ( p-AQ) and p-aminophenol ( p-AP) were computed ab initio (IIF) and by the density functional theory (DFT) method with the 6-31G( d, p) basis set. Cyclic voltammetry with a golden electrode of p-AP solutions in phosphate buffers at pH 7.30 showed that the standard electrode potential of half reaction for p-QI and p-AP was 0.728 V. The standard electrode potentials of half reactions for p-QI and p-AP were calculated using the free energies and solvation energies of p-QI, p-AP, p-benzoquinone ( p-BQ), and hydroquinone ( p-HQ). The results showed that the standard electrode potential of half reaction for p-QI and p-AP was 0.743 V at the B3LYP/6-31G( d, p) level and 0.755 V at the HF/6-31G( d, p) level. The standard electrode potentials computed at the B3LYP/6-31G( d, p) and HF/6-31G( d, p) levels were close to their experimental values.

Song, Y. Z.; Xie, J. M.; Song, Y.; Ye, Y.

2007-10-01

234

A Cross-Cultural Study of Reference Point Adaptation: Evidence from China, Korea, and the US  

ERIC Educational Resources Information Center

|We examined reference point adaptation following gains or losses in security trading using participants from China, Korea, and the US. In both questionnaire studies and trading experiments with real money incentives, reference point adaptation was larger for Asians than for Americans. Subjects in all countries adapted their reference points more…

Arkes, Hal R.; Hirshleifer, David; Jiang, Danling; Lim, Sonya S.

2010-01-01

235

A Cross-Cultural Study of Reference Point Adaptation: Evidence from China, Korea, and the US  

ERIC Educational Resources Information Center

We examined reference point adaptation following gains or losses in security trading using participants from China, Korea, and the US. In both questionnaire studies and trading experiments with real money incentives, reference point adaptation was larger for Asians than for Americans. Subjects in all countries adapted their reference points more…

Arkes, Hal R.; Hirshleifer, David; Jiang, Danling; Lim, Sonya S.

2010-01-01

236

Geometrically asymmetric electrodes for probing electrochemical reaction kinetics: a case study of hydrogen at the Pt-CsH2PO4 interface.  

PubMed

Electrochemical reactions can exhibit considerable asymmetry, with the polarization behavior of oxidation at a given metal|electrolyte interface differing substantially from that of reduction. The reference-less, microcontact electrode geometry, in which the electrode overpotentials are geometrically constrained to the working electrode (by limiting its area) is experimentally convenient, particularly for fuel cell studies, because the results do not rely on accurate placement of a reference electrode nor must oxidant and reductant gases be sealed off from one another. Here, the conditions under which the critical assumption of this geometry applies-that the overpotential at the large-area counter electrode can be ignored-is numerically assessed. It is found that, for cells of sufficiently large area, the effective radius of the counter electrode (which defines the area through which the majority of the current passes) can be expressed directly as a function of electrolyte thickness and the materials properties, sigma, the conductivity of the electrolyte, and k, the reaction rate constant for the electrochemical reaction at zero-bias. From this effective radius and the true radius of the working electrode, the fraction of electrode overpotential at the latter, defined as the extent of isolation, can be readily computed. Experimental studies of hydrogen electro-oxidation/proton electro-reduction at the Pt|CsH(2)PO(4) interface using two cells of differing dimensions both validate the computational results and demonstrate that asymmetry in such reactions are readily revealed in the micro-electrode, reference-less geometry. The study furthermore confirms the insensitivity of the results to the precise placement of the working electrode, while indicating the importance of very high isolation values (>99%) to ensure that overpotential contributions of the counter electrode do not influence the measurements, particularly as bias is increased. PMID:19756291

Sasaki, Kenji A; Hao, Yong; Haile, Sossina M

2009-07-15

237

Principal Point Classification: Applications to Differentiating Drug and Placebo Responses in Longitudinal Studies  

PubMed Central

Principal points are cluster means for theoretical distributions. A discriminant methodology based on principal points is introduced. The principal point classification method is useful in clinical trials where the goal is to distinguish and differentiate between different treatment effects. Particularly, in psychiatric studies where placebo response rates can be very high, the principal point classification is illustrated to distinguish specific drug responders from non-specific placebo responders.

Tarpey, Thaddeus; Petkova, Eva

2009-01-01

238

Principal Point Classification: Applications to Differentiating Drug and Placebo Responses in Longitudinal Studies.  

PubMed

Principal points are cluster means for theoretical distributions. A discriminant methodology based on principal points is introduced. The principal point classification method is useful in clinical trials where the goal is to distinguish and differentiate between different treatment effects. Particularly, in psychiatric studies where placebo response rates can be very high, the principal point classification is illustrated to distinguish specific drug responders from non-specific placebo responders. PMID:20563220

Tarpey, Thaddeus; Petkova, Eva

2010-02-01

239

Deuterium and lithium-6 MAS NMR studies of manganese oxide electrode materials  

NASA Astrophysics Data System (ADS)

Electrolytic manganese dioxide (EMD) is used world wide as the cathode materials in both lithium and alkaline primary (non-rechargeable) batteries. We have developed deuterium and lithium MAS NMR techniques to study EMD and related manganese oxides and hydroxides, where diffraction techniques are of limited value due to a highly defective nature of the structures. Deuterons in EMD, manganite, groutite, and deuterium-intercalated pyrolusite and ramsdellite were detected by NMR, for the first time, and their locations and motions in the structures were analyzed by applying variable temperature NMR techniques. Discharge mechanisms of EMD in alkaline (aqueous) electrolytes were studied, in conjunction with step potential electrochemical spectroscopic (SPECS) method, and five distinctive discharge processes were proposed. EMD is usually heat-treated at about 300--400°C to remove water to be used in lithium batteries. Details of the effects of heat-treatment, such as structural and compositional changes as a function of heat-treatment temperature, were studied by a combination of MAS NMR, XRD, and thermogravimetric analysis. Lithium local environments in heat-treated EMD (HEMD) that were discharged in lithium cells, were described in terms of related environments found in model compounds pyrolusite and ramsdellite where specific Li + sites were detected by MAS NMR and the hyperfine shift scale method of Grey et al. Acid-leaching of Li2MnO3 represents an approach for synthesizing new or modified manganese oxide electrode materials for lithium rechargeable batteries. Progressive removal of lithium from specific crystallographic sites, followed by a gradual change of the crystal structure, was monitored by a combination of NMR and XRD techniques.

Paik, Younkee

240

Studies on the potentiometric thallium(III)-selective carbon paste electrode and its possible applications  

Microsoft Academic Search

Construction, performance characteristics and applications of a carbon paste thallium(III) ion-selective electrode are described.\\u000a The electrode, which is based on ion-associate compounds formed between cetylpyridinium and chlorothallate(III) complexes\\u000a dissolved in tricresyl phosphate as pasting liquid, showed near-Nernstian response over the concentration range of 5.8 × 10–6– 2.9 × 10–3 mol\\/L. Potentiometric titrations of thallium(III) with cetylpyridinium chloride were affected by

K. Vyt?as; E. Khaled; J. Ježková; H. N. A. Hassan; B. N. Barsoum

2000-01-01

241

Intraorbital optic nerve stimulation with penetrating electrodes: in vivo electrophysiology study in rabbits  

Microsoft Academic Search

Purpose  To investigate the response properties of the electrically evoked potentials (EEPs) elicited by intraorbital optic nerve stimulation\\u000a with penetrating electrodes using different stimulus parameters.\\u000a \\u000a \\u000a \\u000a Methods  Visually evoked potentials (VEPs) were recorded as a control and for comparative purposes. Teflon-coated tungsten wire electrodes\\u000a (100 ?m core-diameter, 300 ?m exposed tip) were inserted intraorbitally into the optic nerve. A charge-balanced biphasic current\\u000a was delivered to

Liming Li; Pengjia Cao; Mingjie Sun; Xinyu Chai; Kaijie Wu; Xun Xu; Xiaoxin Li; Qiushi Ren

2009-01-01

242

STUDYING GEOMETRIC FIGURES AT PRIMARY SCHOOL FROM SURFACES TO POINTS  

Microsoft Academic Search

On the one hand, difficulties in geometry in relation with figures are well known and yet studied from different theoretical perspectives. On the other hand, at primary school in France, geometry is generally less considered than numbers. The purpose of this research is to develop some teaching situations usable by any teacher and focussing on one aim: to learn to

Marie-Jeanne Perrin-Glorian

243

Liquid electrode  

DOEpatents

A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

Ekechukwu, A.A.

1994-07-05

244

Control of electrode depth in electroslag remelting  

DOEpatents

A method of and apparatus for controlling an electroslag remelting furnace by driving the electrode at a nominal speed based upon melting rate and geometry while making minor proportional adjustments based on a measured metric of the electrode immersion depth. Electrode drive speed is increased if a measured metric of electrode immersion depth differs from a set point by a predetermined amount, indicating that the tip is too close to the surface of a slag pool. Impedance spikes are monitored to adjust the set point for the metric of electrode immersion depth based upon one or more properties of the impedance spikes.

Melgaard, David K. (Albuquerque, NM); Shelmidine, Gregory J. (Tijeras, NM); Damkroger, Brian K. (Albuquerque, NM)

2002-01-01

245

Muscle channelopathies and critical points in functional and genetic studies  

PubMed Central

Muscle channelopathies are caused by mutations in ion channel genes, by antibodies directed against ion channel proteins, or by changes of cell homeostasis leading to aberrant splicing of ion channel RNA or to disturbances of modification and localization of channel proteins. As ion channels constitute one of the only protein families that allow functional examination on the molecular level, expression studies of putative mutations have become standard in confirming that the mutations cause disease. Functional changes may not necessarily prove disease causality of a putative mutation but could be brought about by a polymorphism instead. These problems are addressed, and a more critical evaluation of the underlying genetic data is proposed.

Jurkat-Rott, Karin; Lehmann-Horn, Frank

2005-01-01

246

Study of Localized Corrosion in Aluminum Alloys by the Scanning Reference Electrode Technique.  

National Technical Information Service (NTIS)

Localized corrosion in 2219-T87 aluminum (Al) alloy, 2195 aluminum-lithium (Al-Li) alloy, and welded 2195 Al-Li alloy (4043 filler) have been investigated using the relatively new scanning reference electrode technique (SRET). Anodic sites are more freque...

M. D. Danford

1995-01-01

247

Nanosized metal catalysts in electrodes for solid polymeric electrolyte fuel cells: an XPS and XRD study  

Microsoft Academic Search

Solid polymeric fuel cells (SPFC) are devices that are able to convert chemical energy into electric energy continuously without any ambient pollution. The electrodes of this type of cells are layered structures, composed of a carbon support, a diffusive layer and a catalytic layer, usually platinum clusters dispersed on amorphous carbon microparticles, whose properties, at atomic and molecular level, determine

R. Giorgi; P Ascarelli; S Turtù; V Contini

2001-01-01

248

Study of Plasma Arc Welded Reactor Materials. Plasma Arc Welding Using Hot Wire Electrodes.  

National Technical Information Service (NTIS)

The effects of single-run and double-run plasma arc welding using a hot wire electrode on the structure of the HAZ of the fine-grained structural steels 22 NiMoCr 3 7 and 20 MnMoNi 5 5 were investigated, with particular regard to the behaviour of that reg...

K. O. Trarbach

1980-01-01

249

EHD study of the corona wind between wire and plate electrodes  

Microsoft Academic Search

The corona wind, with a velocity of several meters per second, is caused by applying high electric tension to bring about corona discharge in gases. In this paper the corona wind is experimentally and theoretically analyzed from an electrohydrodynamical (EHD) standpoint. Experiments have been performed mainly in nitrogen by a two-dimensional electrode arrangement of a fine wire anode and a

A. Yabe; Y. Mori; K. Hijikata

1978-01-01

250

An electrochemical quartz crystal microbalance study of the hydrogen underpotential deposition at a Pt electrode  

Microsoft Academic Search

The effect of various ions on the frequency response of a quartz supported platinum electrode in the hydrogen upd region was investigated. The experiments were carried out in alkaline solution, and in acid solutions with various concentrations of chloride or sulfate ions. Traces of specifically adsorbed ions, such as chloride ions, were readily detected with the EQCM. On the other

F Gloaguen; J.-M Léger; C Lamy

1999-01-01

251

Study on stainless steel electrode based on dynamic aluminum liquid corrosion mechanism  

Microsoft Academic Search

Scanning electrion microscope (SEM) was performed for investigations on the corrosion mechanism of stainless steel electrode in dynamic melting aluminum liquid. Microstructures and composition analysis was made by electron probe analysis (EPA) combined with metallic phase analysis. It can be concluded that the corrosion process is mainly composed of physical corrosion (flowing and scouring corrosion) and chemical corrosion (forming FeAl

Hua HOU; Ruifeng YANG

2009-01-01

252

Feasibility study of photoelectrochemical degradation of methylene blue with three-dimensional electrode-photocatalytic reactor  

Microsoft Academic Search

The photoelectrochemical degradation of methylene blue in aqueous solution was investigated with three-dimensional electrode-photocatalytic reactor. It was found that the methylene blue could be degraded more efficiently by photoelectrochemical process than by photocatalytic oxidation or electrochemical oxidation alone. The decolorization efficiency and COD reduction were 95% and 87% for a photoelectrochemical process, respectively, while they were only 78% and 68%

Tai-Cheng An; Xi-Hai Zhu; Ya Xiong

2002-01-01

253

A novel device for the wire beam electrode method and its application in the ennoblement study  

Microsoft Academic Search

A novel device used in the wire beam electrode (WBE) method was developed in our lab. The system consists of standard modules, and is controlled by a LabVIEW software (National Instruments Co., NI). Since all the components in this WBE test device are commercially available, and the detailed information of the modules can be readily accessed by researchers, the system

Xia Zhang; Wei Wang; Jia Wang

2009-01-01

254

Comparative studies of configurations and preparation methods for direct methanol fuel cell electrodes  

Microsoft Academic Search

Catalyst-coated membrane (CCM) and catalyzed diffusion medium (CDM) prepared either by brush painting method or by spraying method were compared for direct methanol fuel cell (DMFC) anode and cathode. The pore structure and the morphology of the electrodes were characterized by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). Internal resistance corrected polarization curves were employed to separate the

Qing Mao; Gongquan Sun; Suli Wang; Hai Sun; Guoxiong Wang; Yan Gao; Aiwei Ye; Yang Tian; Qin Xin

2007-01-01

255

STUDY ON PULSED DC-SPUTTERING OF IRIDIUM OXIDE FOR IMPLANTABLE ELECTRODES  

Microsoft Academic Search

A pulsed-DC reactive sputtering technique was used for iridium oxide thin-film deposition. Frequency, pulse width, oxygen flow and deposition time were changed over several deposition sessions, regarding implantable electrode applications. Surface and electrochemistry analysis were performed for deposition evaluation. The results evidenced that the deposited film sputtered with 2 sccm of oxygen flow and 50 KHz pulse frequency, achieved best

N. S. Dias; A. Ferreira da Silva; A. van Ooyen; P. M. Mendes; J. A. Afonso; J. H. Correia; W. Mokwa; U. Schnakenberg

2007-01-01

256

The oxidation of tyrosine and tryptophan studied by a molecular dynamics normal hydrogen electrode  

SciTech Connect

The thermochemical constants for the oxidation of tyrosine and tryptophan through proton coupled electron transfer in aqueous solution have been computed applying a recently developed density functional theory (DFT) based molecular dynamics method for reversible elimination of protons and electrons. This method enables us to estimate the solvation free energy of a proton (H{sup +}) in a periodic model system from the free energy for the deprotonation of an aqueous hydronium ion (H{sub 3}O{sup +}). Using the computed solvation free energy of H{sup +} as reference, the deprotonation and oxidation free energies of an aqueous species can be converted to pK{sub a} and normal hydrogen electrode (NHE) potentials. This conversion requires certain thermochemical corrections which were first presented in a similar study of the oxidation of hydrobenzoquinone [J. Cheng, M. Sulpizi, and M. Sprik, J. Chem. Phys. 131, 154504 (2009)]. Taking a different view of the thermodynamic status of the hydronium ion, these thermochemical corrections are revised in the present work. The key difference with the previous scheme is that the hydronium is now treated as an intermediate in the transfer of the proton from solution to the gas-phase. The accuracy of the method is assessed by a detailed comparison of the computed pK{sub a}, NHE potentials and dehydrogenation free energies to experiment. As a further application of the technique, we have analyzed the role of the solvent in the oxidation of tyrosine by the tryptophan radical. The free energy change computed for this hydrogen atom transfer reaction is very similar to the gas-phase value, in agreement with experiment. The molecular dynamics results however, show that the minimal solvent effect on the reaction free energy is accompanied by a significant reorganization of the solvent.

Costanzo, Francesca; Valle, Raffaele Guido Della [Dipartimento di Chimica Fisica e Inorganica, Universita di Bologna and INSTM-UdR Bologna, Viale Risorgimento 4, I-40136 Bologna (Italy); Sulpizi, Marialore; Sprik, Michiel [Department of Chemistry, University of Cambridge, Cambridge CB2 1EW (United Kingdom)

2011-06-28

257

Subdural Electrodes  

PubMed Central

Subdural electrodes are frequently used to aid in the neurophysiological assessment of patients with intractable seizures. We review the indications for these, their uses for localizing epileptogenic regions and for localizing cortical regions supporting movement, sensation, and language.

Lesser, Ronald P.; Crone, Nathan E.; Webber, W.R.S.

2010-01-01

258

A study of irreversible electrode processes under steady-state flowing solution conditions with a microelectrode based scanning electrochemical detector  

Microsoft Academic Search

A study of the irreversible oxidation of l-tyrosine and a series of catecholamines has been undertaken at a microelectrode under both flow analysis and reversed-phase liquid chromatography (LC) conditions. Experimental parameters (electrode radius 5 ?m, flow rate 1.0 ml min?1, scan rate in the range 1–2 V s?1) were chosen so that the complete current-voltage curve could be obtained via

Russell J. Tait; Barrie C. Finnin; Barry L. Reed; Alan M. Bond

1996-01-01

259

A comparative study of synthetic graphite and Li electrodes in electrolyte solutions based on ethylene carbonate-dimethyl carbonate mixtures  

Microsoft Academic Search

This work entails a comparative study of both Li and synthetic graphite electrodes in electrolyte solutions based on ethylene and dimethyl carbonates (EC-DMC) and the impact of the salt used [from the LiAsFâ, LiClOâ, LiPFâ, LiBFâ, and LiN(SOâCFâ)â list]. The presence of some additives in solutions (e.g., LiâCOâ, COâ, tributylamine) and the effect of the particle size of the carbon

D. Aurbach; B. Markovsky; A. Schechter; Y. Ein-Eli; H. Cohen

1996-01-01

260

Electropolymerization of chlorinated phenols on a Pt electrode in alkaline solution. Part IV: A gas chromatography mass spectrometry study  

Microsoft Academic Search

The electropolymerization of phenol and chlorinated phenols (monochlorophenols, dichlorophenols, 2,3,6-, 2,4,6-, 2,4,5-trichlorophenols and pentachlorophenol) was studied on a platinum electrode at 0.78 V vs SHE in alkaline 1 M NaOH aqueous solutions containing 0.1 M of the phenols. The low molecular weight reaction products were investigated by means of gas chromatography mass spectrometry (GCMS). Product analyses show that oligomers (dimers,

Z. Ežerskis; Z. Jusys

2002-01-01

261

Comparative study of hydrogen peroxide electro-generation on gas-diffusion electrodes in undivided and membrane cells  

Microsoft Academic Search

The generation of hydrogen peroxide by means of the cathodic reduction of oxygen at gas-diffusion electrodes with a near 100%\\u000a current efficiency was achieved in concentrations sufficient for the mineralization of refractory organics in Fenton treatment.\\u000a A decrease in current efficiency over time at high temperatures and high current densities was observed. The polarization\\u000a study carried out in potentiostatic, potentiodynamic

G. R. Agladze; G. S. Tsurtsumia; B.-I. Jung; J.-S. Kim; G. Gorelishvili

2007-01-01

262

An in situ X-ray absorption spectroscopy study of InSb electrodes in lithium batteries  

Microsoft Academic Search

We present a detailed in situ extended X-ray absorption fine-structure spectroscopy (EXAFS) study of structural and compositional changes in InSb intermetallic electrodes under electrochemical cycling conditions in a lithium battery. Analysis of the EXAFS data shows that Li is inserted into and In is extruded from the zinc-blende-type InSb network during the first discharge from 1.5 to 0.5 V, yielding

A. J. Kropf; H. Tostmann; C. S. Johnson; J. T. Vaughey; M. M. Thackeray

2001-01-01

263

Study of engineering ceramic machining with a new design of ripple controlled microdetonation of electrode arc striking  

Microsoft Academic Search

Based on the principle of strong shock wave generating transient dynamic high-pressure, physical theory of vacuum discharge,\\u000a and high-power pulse technology, this study developed a new machining system of ripple controlled microdetonation of electrode\\u000a arc striking (MDEAS), which was specially used to machine hard and crisp materials, such as ceramic. The topographies such\\u000a as hole, ladder plane, column surface, and

Xinli Tian; Junfei Yang; Chao Liu; Baoguo Zhang; Fang Guo; Aibing Yu

2010-01-01

264

Fluorescence quenching studies of potential-dependent DNA reorientation dynamics at glassy carbon electrode surfaces.  

PubMed

The potential-dependent reorientation dynamics of double-stranded DNA (ds-DNA) attached to planar glassy carbon electrode (GCE) surfaces were investigated. The orientation state of surface-bound ds-DNA was followed by monitoring the fluorescence from a 6-carboxyfluorescein (FAM6) fluorophore covalently linked to the distal end of the DNA. Positive potentials (i.e., +0.2 V vs open circuit potential, OCP) caused the ds-DNA to align parallel to the electrode surface, resulting in strong dipole-electrode quenching of FAM6 fluorescence. Switching of the GCE potential to negative values (i.e., -0.2 V vs OCP) caused the ds-DNA to reorient perpendicular to the electrode surface, with a concomitant increase in FAM6 fluorescence. In addition to the very fast (submilliseconds) dynamics of the initial reorientation process, slow (0.1-0.9 s) relaxation of FAM6 fluorescence to intermediate levels was also observed after potential switching. These dynamics have not been previously described in the literature. They are too slow to be explained by double layer charging, and chronoamperometry data showed no evidence of such effects. Both the amplitude and rate of the dynamics were found to depend upon buffer concentration, and ds-DNA length, demonstrating a dependence on the double layer field. The dynamics are concluded to arise from previously undetected complexities in the mechanism of potential-dependent ds-DNA reorientation. The possible origins of these dynamics are discussed. A better understanding of these dynamics will lead to improved models for potential-dependent ds-DNA reorientation at electrode surfaces and will facilitate the development of advanced electrochemical devices for detection of target DNAs. PMID:22881147

Li, Qin; Cui, Chenchen; Higgins, Daniel A; Li, Jun

2012-08-23

265

Lifetime studies of high power rhodium/tungsten and molybdenum electrodes for application to AMTEC (alkali metal thermal-to-electric converter)  

NASA Astrophysics Data System (ADS)

A detailed and fundamental model for the electrochemical behavior of AMTEC electrodes is developed which can aid in interpreting the processes which occur during prolonged operation of these electrodes. Because the sintering and grain growth of metal particles is also a well-understood phenomenon, the changes in electrode performance which accompany its morphological evolution may be anticipated and modeled. The grain growth rate observed for porous Mo AMTEC electrodes is significantly higher than that predicted from surface diffusion data obtained at higher temperatures and incorporated into the grain growth model. The grain growth observed under AMTEC conditions is also somewhat higher than that measured for Mo films on BASE (beta-alumina solid electrolyte) substrates in vacuum or at similar temperatures. Results of modeling indicate that thin Mo electrodes may show significant performance degradation for extended operation (greater than 10,000 h) at higher operating temperatures (greater than 1150 K), whereas W/Rh and W/Pt electrodes are expected to show adequate performance at 1200 K for lifetimes greater than 10,000 h. It is pointed out that current collection grids and leads must consist of refractory metals such as Mo and W which do not accelerate sintering or metal migration.

Williams, R. M.; Jeffries-Nakamura, B.; Underwood, M. L.; O'Connor, D.; Ryan, M. A.; Kikkert, S.; Bankston, C. P.

266

Molecular second harmonic generation studies of methylene blue chemisorbed onto a sulfur-modified polycrystalline platinum electrode  

SciTech Connect

The resonant molecular second harmonic generation (SHG) response of a monolayer of adsorbed methylene blue is studied in situ on a polycrystalline platinum electrode modified by the deposition of a monolayer of chemisorbed sulfur. The sulfur monolayer prevents the irreversible decomposition of the dye molecules on the platinum electrode and ensures that the contributions to the surface nonlinear susceptibility from the metal and from the methylene blue remain separable. At an incident angle of 40{degree}, the resonant molecular SHG signal from the methylene blue monolayer dominates the nonlinear optical response of the interface, and the potential dependence of the resonant SHG signal matches that expected during the electrochemical reduction and reoxidation of the chemisorbed methylene blue.

Campbell, D.J.; Higgins, D.A.; Corn, R.M. (Univ. of Wisconsin, Madison (USA))

1990-05-03

267

Numerical study on the spark ignition characteristics of a methane-air mixture using detailed chemical kinetics. Effect of equivalence ratio, electrode gap distance, and electrode radius on MIE, quenching distance, and ignition delay  

SciTech Connect

The minimum ignition energy (MIE) is an important property for designing safety standards and understanding the ignition process of combustible mixtures. Even though the formation of flame kernels in quiescent methane-air mixtures has been simulated numerically, the ignition mechanism has never been satisfactorily explained. This study investigated the spark ignition of methane-air mixtures through a numerical analysis using detailed chemical kinetics consisting of 53 species and 325 elementary reactions while considering the heat loss to the electrode. The simulation was used to investigate the quenching distance and the effects on the MIE of the electrode size, electrode gap distance, ignition duration, and equivalence ratio. The effect of the equivalence ratio on the ignition delay time was also examined. The simulated results showed the same trend as previous experimental results. (author)

Han, Jilin; Yamashita, Hiroshi; Hayashi, Naoki [Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya-shi, Aichi (Japan)

2010-07-15

268

Recent advances in laparoscopic partial nephrectomy: comparative study of electrosurgical snare electrode and ultrasound dissection.  

PubMed

Although technically feasible, laparoscopic partial nephrectomy (LPN) using conventional instrumentation presents the intraoperative challenge of hemostasis, creating a flush (i.e., precise guillotine) incision, and closure of the collecting system. In an effort to resolve these technical problems, we used a unique electrosurgical snare electrode (ESE) in combination with an ERBE electrosurgical generator and compared its effectiveness with that of two ultrasonic dissectors (Cavitron Ultrasonic Surgical Aspirator [CUSA] and harmonic scalpel [HS]) in performing LPN. Twelve female minipigs underwent right lower-pole LPN using one of the aforementioned modalities. Six weeks later, in the same animals, a left lower-pole LPN was performed using the same device, thereby providing an acute and chronic renal remnant to examine. The animals were harvested, and transverse and perpendicular histologic sections were prepared of the cut surface of each specimen. The weights of the LPN specimens and the remaining kidney were also recorded. The time required for partial nephrectomy, degree of hemostasis (i.e., blood loss), ease of excising the targeted tissue, changes in renal function, tissue reactivity, and depth of damage to the surface of the remaining renal parenchyma were measured for each device. All 12 procedures were successful using the ultrasonic dissection, and 11 procedures were successful using the ESE. The ESE was significantly faster than the two forms of ultrasonic dissection (p < 0.0001) and produced less intraoperative bleeding (P = 0.002). Both forms of ultrasonic energy produced significantly deeper parenchymal injury in the acute surgical specimen (P = 0.03) and more parenchymal fibrosis and chronic inflammation in the chronic surgical specimens (P = 0.007) than the ESE. None of the animals exhibited any extravasation from the incised collecting system when studied by retrograde pyelography 6 weeks postoperatively at the time of left LPN and harvest. The function of the renal remnant was consistent with the size of the partial nephrectomy specimen. No hypertension developed in any of the study animals. Our results using a unique electrosurgical snare probe show it to have potential advantages as a rapid, hemostatic method for performing a partial nephrectomy. We believe that this instrument may represent an important tool for performing nephron-sparing surgery via an open or laparoscopic approach. Clinical trials are in progress. PMID:9048292

Elashry, O M; Wolf, J S; Rayala, H J; McDougall, E M; Clayman, R V

1997-02-01

269

Radiofrequency electrode vibration-induced shear wave imaging for tissue modulus estimation: A simulation study  

PubMed Central

Quasi-static electrode displacement elastography, used for in-vivo imaging of radiofrequency ablation-induced lesions in abdominal organs such as the liver and kidney, is extended in this paper to dynamic vibrational perturbations of the ablation electrode. Propagation of the resulting shear waves into adjoining regions of tissue can be tracked and the shear wave velocity used to quantify the shear (and thereby Young’s) modulus of tissue. The algorithm used utilizes the time-to-peak displacement data (obtained from finite element analyses) to calculate the speed of shear wave propagation in the material. The simulation results presented illustrate the feasibility of estimating the Young’s modulus of tissue and is promising for characterizing the stiffness of radiofrequency-ablated thermal lesions and surrounding normal tissue.

Bharat, Shyam; Varghese, Tomy

2010-01-01

270

Study on the anode behavior of Sn and Sn–Cu alloy thin-film electrodes  

Microsoft Academic Search

Anodes based on tin metal powder offer large specific capacity, but also exhibit large irreversible capacity and poor cycle performance. In order to use them as a negative electrode for lithium secondary batteries, we focused on the electrodepositing process and investigated an electrodeposited tin layer on copper foil. In the full charge–discharge condition, charging and discharging between 0 and 2.0V

Noriyuki Tamura; Ryuji Ohshita; Masahisa Fujimoto; Shin Fujitani; Maruo Kamino; Ikuo Yonezu

2002-01-01

271

Improved performances of nanosilicon electrodes using the salt LiFSI: a photoelectron spectroscopy study.  

PubMed

Silicon is a very good candidate for the next generation of negative electrodes for Li-ion batteries, due to its high rechargeable capacity. An important issue for the implementation of silicon is the control of the chemical reactivity at the electrode/electrolyte interface upon cycling, especially when using nanometric silicon particles. In this work we observed improved performances of Li//Si cells by using the new salt lithium bis(fluorosulfonyl)imide (LiFSI) with respect to LiPF6. The interfacial chemistry upon long-term cycling was investigated by photoelectron spectroscopy (XPS or PES). A nondestructive depth resolved analysis was carried out by using both soft X-rays (100-800 eV) and hard X-rays (2000-7000 eV) from two different synchrotron facilities and in-house XPS (1486.6 eV). We show that LiFSI allows avoiding the fluorination process of the silicon particles surface upon long-term cycling, which is observed with the common salt LiPF6. As a result the composition in surface silicon phases is modified, and the favorable interactions between the binder and the active material surface are preserved. Moreover a reduction mechanism of the salt LiFSI at the surface of the electrode could be evidenced, and the reactivity of the salt toward reduction was investigated using ab initio calculations. The reduction products deposited at the surface of the electrode act as a passivation layer which prevents further reduction of the salt and preserves the electrochemical performances of the battery. PMID:23763546

Philippe, Bertrand; Dedryvère, Rémi; Gorgoi, Mihaela; Rensmo, Håkan; Gonbeau, Danielle; Edström, Kristina

2013-06-25

272

Chemically modified electrodes and related solution studies. Final technical report, January 15, 1991--January 14, 1992  

SciTech Connect

This report is divided into 5 sections: Ru{sub 4}/Fe complexes of tetra(4{prime}-methyl-2,2{prime}-bipyridine)porphyrin--catalytic epoxidation of olefins; water oxidation catalysis by doubly linked {mu}-oxo ruthenium complexes; polymer films formed by oxidation of transition metal electrodes into solutions of bisbipyridinealkane ligands; polymer films containing [CpMo({mu}-S)]{sub 2}S{sub 2}CHR dinuclear clusters;and conducting polymer films for catalyst incorporation.

Elliott, C.M.

1993-04-01

273

CO electrooxidation on a polycrystalline Pt electrode: A wall-jet EQCN study  

Microsoft Academic Search

Pre-adsorbed and bulk (continuous) CO oxidation on a polycrystalline Pt electrode were examined in a wall-jet electrochemical quartz crystal nanobalance (EQCN) setup, using both differential and integral evaluation of the EQCN data, to get further insights into the kinetics and mechanism of this important fuel-cell related electrocatalytic reaction. The hydrogen underpotential adsorption–desorption features in the base cyclic voltammogram of a

G. Stalnionis; L. Tamašauskait?-Tamaši?nait?; V. Pautienien?; Z. Jusys

2006-01-01

274

Study of enzyme biosensor based on carbon nanotubes modified electrode for detection of pesticides residue  

Microsoft Academic Search

The paper describes a controllable layer-by-layer (LBL) self-assembly modification technique of multi-walled carbon nanotubes (MWNTs) and poly(diallyldimethylammonium chloride) (PDDA) towards glassy carbon electrode (GCE), Acetylcholinesterase (AChE) was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected by using i-t technique based on the modified Ellman method. Then the composition of carbaryl were

Shu Ping Zhang; Lian Gang Shan; Zhen Ran Tian; Yi Zheng; Li Yi Shi; Deng Song Zhang

2008-01-01

275

Rotating cylinder electrode study of the effect of activated polyacrylamide on surface roughness of electrodeposited copper  

Microsoft Academic Search

The development of a new organic additive based on polyacrylamide is reported for copper electrowinning (EW) and electrorefining (ER) in which a rotating cylinder electrode (RCE) is applied as a novel method of determining surface roughness. The effect of hydrodynamics of the electrolyte (Cu2+=36 g\\/L; H2SO4=160 g\\/L and Cl?=25 mg\\/L) on the surface roughness of the copper deposit was first validated against the

C. Fabian; M. J. Ridd; M. Sheehan

2006-01-01

276

Thermal-stability studies of electrode materials for lithium-ion batteries  

Microsoft Academic Search

The thermal stability of lithium-ion batteries has recently attracted attention for two major reasons. (1) Attempts to make large-size cells used in power tools, E-bikes and EVs. Large cells have lower surface area to volume ratios and hence heat dissipation is more problematic than 18650-size cells. Safety problems, therefore, for large cells are more serious. (2) Next generation high-capacity electrodes

Junwei Jiang

2005-01-01

277

Study of electrochemiluminescence of lucigenin at glassy carbon electrodes in NaOH solution  

Microsoft Academic Search

Two cathodic electrochemiluminescence (ECL) pathways were firstly resolved at glassy carbon electrodes for alkaline lucigenin system by using the potential-resolved ECL method. The light emitters for the ECL emission were identified as excited N-methylacridone and excited lucigenin molecules according to the in situ UV–visible absorption spectra and the fluorescence spectra. Two mechanistic schemes are proposed: (1) the pathway for the

Yu-Gang Sun; Hua Cui; Xiang-Qin Lin

2001-01-01

278

ATR SEIR study of anions and water adsorbed on platinum electrode  

NASA Astrophysics Data System (ADS)

Adsorbed species on bare Pt, and UPD-Pb or UPD-Cu/Pt electrodes were characterized in HClO4 or H2SO4 solutions at various potentials using attenuated total reflection (ATR) surface enhanced infrared absorption (SEIRA) spectroscopy. On the bare Pt electrode, ClO4- anions were observed at 1120 1095 cm-1 at +0.0 < E < +0.6 V, solvated by water molecules with OH stretching absorption at 3600 cm-1 and HOH bending mode at 1610 1620 cm-1. In addition to the S OH totally symmetric mode at 950 cm-1, adsorbed sulfate species gave two bands at 1230 1100 cm-1 between 0.0 V < E < +0.8 V that are assigned to ?3 (symmetric stretch of S O in SO3) of HSO4- ions with different coordination based on the peak shift by isotope substitution. At more negative potential, solely water molecules adsorb on the bare Pt surfaces. In contrast, it was found that electrolyte anions such as bisulfate and ClO4- with hydrating water molecules adsorb onto the UPD-Pb/Pt and UPD-Cu/Pt electrodes even at much negative potentials, e.g. -0.2 V for UPD-Pb.

Futamata, Masayuki; Luo, Liqiang; Nishihara, Chizuko

2005-10-01

279

Studies on a non-thermal pulsed corona plasma between two parallel-plate electrodes in water  

NASA Astrophysics Data System (ADS)

A non-thermal plasma generated between two parallel-plate electrodes submerged in water was studied in this work. The surface of one of the stainless-steel electrodes (the cathode) was coated with a ceramic layer of Al2O3. This reactor cell was connected to a water cycle and the discharge was carried out in a closed loop and therefore an equilibrium was established during discharge. The dependence of hydrogen peroxide formation as an indicator for the generation of most important oxidative species OH radicals on the pulse repetition rate, the solution conductivity and the pH of the solution was investigated. The highest yield of H2O2 (3.5 mg L-1) was obtained at 20 pps in a NaCl solution with a conductivity of 400 µS cm-1 and pH 7 in 90 min. The maximum energy efficiency of ˜0.1 g kWh-1 H2O2 was obtained. The surface of the coated electrodes, before and after applying of electrical discharges, was analysed by scanning electron microscopy. During the discharge process, the coating was destroyed and the formation of H2O2 decreased to 10% after discharging of nearly 35 h.

Sein, M. M.; Nasir, Z. Bin; Telgheder, U.; Schmidt, T. C.

2012-06-01

280

Study of the mechanism of the hydrogen evolution reaction at Raney nickel electrodes in the presence of organic compounds  

SciTech Connect

The hydrogen evolution reaction (HER) has been studied at Raney nickel electrodes in the absence and presence of several organic compounds. A poisoning effect of nonreducible organic substrates on the kinetics of the HER was studied. It was found that only pyridine had a strong inhibiting effect on the HER. A compound having one reducible double bond, trans-cinnamic acid, was used as a model in a study of the mechanism of the electrocatalytic hydrogenation (ECH) reaction and its influence on the HER. It was established that the HER proceeds via the Volmer-Hyrovsky reaction mechanism, and the slowest step is the Heyrovsky reaction.

Cheong, A.K.; Lasia, A.; Lessard, J. (Univ. de Sherbrooke, Quebec (Canada). Dept. de Chimie)

1994-04-01

281

Cermet electrode  

DOEpatents

Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

Maskalick, Nicholas J. (Pittsburgh, PA)

1988-08-30

282

Magnetohydrodynamic electrode  

DOEpatents

An electrode capable of withstanding high temperatures and suitable for use as a current collector in the channel of a magnetohydrodynamic (MHD) generator consists of a sintered powdered metal base portion, the upper surface of the base being coated with a first layer of nickel aluminide, an intermediate layer of a mixture of nickel aluminide - refractory ceramic on the first layer and a third or outer layer of a refractory ceramic material on the intermediate layer. The sintered powdered metal base resists spalling by the ceramic coatings and permits greater electrode compliance to thermal shock. The density of the powdered metal base can be varied to allow optimization of the thermal conductivity of the electrode and prevent excess heat loss from the channel.

Marchant, David D. (Richland, WA); Killpatrick, Don H. (Orland Park, IL)

1978-01-01

283

Study of the cloud point behavior of high oleate ester-derived nonionic surfactant  

NASA Astrophysics Data System (ADS)

The cloud point behavior of high oleate ester-derived nonionic surfactant has been studied. The effect of various polyethoxylate chain lengths (polyethylene glycol with ethylene oxide monomer 7, 11 and 16 units) as the surfactant's hydrophilic head and the effect of sodium chloride and ionic surfactants on the cloud points of nonionic surfactants synthesized were investigated. When the chain length of polyethoxylate increased, the cloud point of the synthesized nonionic surfactant also increased. Sodium chloride was found to depress the cloud point values of the formed nonionic surfactants with a linear decrease in relation to the concentration of sodium chloride used. Ionic surfactants lifted the cloud points of synthesized nonionic surfactant but in the presence of sodium chloride, the cloud point of mixed ionic-nonionic solution was suppressed.

Tan, Isa M.; Lee, Susan Y. C.; Mushtaq, M.

2012-09-01

284

Study of reversible electrode reaction and mixed ionic and electronic conduction of lithium phosphate electrolyte for an electrochemical CO2 gas sensor  

NASA Astrophysics Data System (ADS)

An electrochemical CO2 gas sensor with lithium ion conductor was developed and characterized in order to examine the potential for real-life applications and understand its sensing mechanism. Li2CO3 and Li2TiO3 + TiO2 mixture were used as a sensing and a reference auxiliary phase, respectively. This electrochemical cell with a solid state Li3PO4 electrolyte has shown good selectivity, sensitivity and linear response in laboratory and automobile exhaust tests. However, the sensor response to CO2 gas showed a systematic deviation from the Nernst equation. Measured EMF did not agree with that calculated from the Nernst equation, even though it followed logarithmic behavior. Moreover, high sensitivity was observed for high CO2 concentrations (5˜50%), compared to that for concentrations (500˜5000 ppm). Two possible reasons for this deviation are: (1) reversibility of electrode reaction and (2) mixed ionic and electronic conduction of the electrolyte. Unless electrode reaction is fast enough, electrode polarization can easily induce overpotential. Pure ionic conduction of electrolyte is also necessary to avoid EMF loss during open circuit potential measurement. EIS (Electrochemical Impedance Spectroscopy) was used to study electrode kinetics. We found that Li2TiO3 + TiO2 mixture reference electrode reaction is sluggish showing large electrode impedance. This impedance, however, was not affected by gas concentration change. On the other hand, that at the Li2CO3 sensing electrode is relatively small and it increased with decreased CO2 and O 2 concentration. It was also observed that these electrode impedances induced the overpotential when the current flowed through the sensor. This electrode overpotential problem was minimized by mixing gold powder or porous sputtered gold electrode increasing effective reaction sites of the electrode. New electrode design improved the sensor EMF closer to the Nernstian values, however, the discrepancy still remained. Moreover, at higher sensor operating temperatures (T > 500°C), the sensitivity deviated even further from the Nernstian value. Therefore, the temperature dependence of the current sensor clearly indicates that the non-Nernstian behavior is not just due to non-reversible electrode reaction. More significant effect on the non-Nernstain behavior is due to mixed ionic and electronic conduction of Li3PO4 electrolyte. Based on the EMF measurement and a modified Nernst equation, the transference number was estimated and the conduction domain boundary separating the n-type from the ionic conduction was constructed. (Abstract shortened by UMI.)

Lee, Chong-Hoon

285

Radiofrequency Ablation with a New Perfused-Cooled Electrode Using a Single Pump: An Experimental Study in Ex Vivo Bovine Liver  

SciTech Connect

The purpose of this study was to assess the efficacy of a new perfused-cooled electrode that uses a single pump for creating a large ablation zone in explanted bovine liver. This was done by comparing with the radiofrequency (RF) ablation zones that were created with a monopolar cooled electrode to the RF ablation zones that were created by the new perfused-cooled electrode. We developed a new perfused-cooled electrode that uses a single pump by modifying a 17-gauge cooled electrode (Radionics) with a 2.5-cm outer metallic sheath (15-gauge) in order to allow use of the internal cooling water (5.85 % hypertonic saline) for the infused saline. Thirty ablation zones were created in explanted bovine livers (12-min ablation cycle; pulsed technique; 2000 mA, maximum) with three different regimens: group A, RF ablation with the 17-gauge cooled electrode; group B, RF ablation with the 15-gauge cooled electrode; group C, RF ablation with the perfused-cooled electrode. T2-weighted magnetic resonance (MR) imaging was obtained immediately after RF ablation for calculating volumes of the ablation zone. Following MR imaging, the ablation zones were excised and measured for transverse diameters and vertical diameters. The transverse diameter, vertical diameter, and the calculated volumes of the ablation zones on MR imaging were compared among the groups. Ablation zones created with the perfused-cooled electrode (group C) were significantly larger than those created with the 17-gauge cooled electrode (group A) and the 15-gauge cooled electrode (group B) according to the transverse diameter and vertical diameter on the gross specimens (p < 0.05): 3.6 {+-} 0.38 cm and 4.4 {+-} 0.20 cm in group A, 3.7 {+-} 0.08 cm and 4.6 {+-} 0.16 cm in group B, and 5.4 {+-} 0.65 cm and 6.0 {+-} 0.56 cm in group C, respectively. On the MR imaging, the calculated volumes of the ablation zones in group C were significantly larger than those in groups A and B (p < 0.05): 23.1 {+-} 8.7 cm{sup 3} in group A, 28.9 {+-} 5.7 cm{sup 3} in group B, and 80.0 {+-} 34 cm{sup 3} in group C, respectively. A new perfused-cooled electrode using a single pump could efficiently increase the size of the ablation zone in liver compared with a monopolar cooled electrode, and this was due to its simultaneous use of internal cooling and saline infusion.

Kim, Seung Kwon [Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Department of Radiology (Korea, Republic of)], E-mail: radi@lycos.co.kr; Seo, Jung Wook [Ilsan Paik Hospital, Inje University School of Medicine, Department of Diagnostic Radiology (Korea, Republic of)

2005-12-15

286

Study on cloud points of Triton X-100-cationic gemini surfactants mixtures: A spectroscopic approach  

Microsoft Academic Search

This study investigates the effects of various cationic surfactants on the cloud point (CP) of the nonionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The values of CPs for Triton X-100 can be measured directly because TX-100 has an average number of oxyethylene units per

Halide Akbas; Mesut Boz; Çi?dem Bat?göç

2010-01-01

287

Studying the movement of high-tech Rodentia: pointing and dragging  

Microsoft Academic Search

This study compares seven input devices (mouse, touchsereen, two trackba.lls, mousepen,touchp@ and joystick) performing a star tracing task. Along with the device comparisons, the diffemtce between moving with the selector button pressed (dragging) or with the button released (pointing) is examined. Recent work has found that dragging is slower and more error prone than pointing when using a mouse, stylus

Oryx Cohen; Shawna Meyer; Erik Nilsen

1993-01-01

288

A study of the point spread function in scintillation camera collimators based on Fourier analysis  

Microsoft Academic Search

A new technique for evaluating the point spread function of parallel hole collimators in scintillation cameras is studied. The collimator function is developed into a Fourier series and the intensity distribution in the detector plane for a point source is given by a mathematical expression that depends on the object position and on the collimator parameters. The septal penetration effect

S. Miracle; M. J. Yzuel; S. Millan

1979-01-01

289

Charging efficiency improvement by structuring lithium battery electrodes  

NASA Astrophysics Data System (ADS)

For atomic intercalation into an infinite long solid electrode, Haftbaradaran et al. [Appl. Phys. Lett. 96, 091909 (2010)] have pointed out that a coupling between internal stresses and activation energy for diffusion may result in surface locking instability accompanied by very large stresses near the electrode surface, significantly limiting the overall charging rate for high energy density lithium batteries. In the present study, we applied this model to the cylindrical electrode with finite length and found that free ends of the electrode may help to release surface stress within certain extent to each of them and postpone the surface locking of diffusion to occur. Following this finding, we further created parallel grooves on the electrode surface and quantitatively investigated the influences of the groove size and interval to the stress distribution and critical charging current density under galvanostatic charging and discharging conditions. It shows that such treatment of surface slotting to electrodes can significantly decrease the mechanical stresses during atomic intercalation and extraction, and improve the electrode charging efficiency, providing some beneficial inspirations to the Lithium battery technology.

Liu, Xiaojing; Zhou, Youhe; Zheng, Xiaojing; Wang, Jizeng

2012-06-01

290

[Study of solanesol adsorbed on platinum electrode by surface enhanced Raman scattering].  

PubMed

The normal Raman spectrum (RRS) of solanesol molecules and surface enhanced raman scattering (SERS) of these molecules adsorbted on Pt electrode surface are reported in this paper. By comparison that the results show that the molecules of solanesol is adsorbed on the Pt surface through the C=C bond. The large difference between RRS and SERS demonstrates that the interaction between the molecules and Pt surface is rather strong and this interaction leads to a large disturbance to the molecules structure of solanesol. PMID:12953530

Yin, Guo-sheng; Zhao, Ge; Du, Yin-xiao; Zhang, Jing-lai; Liu, Kuai-zhi; Mo, Yu-jun

2003-06-01

291

Studies of the adsorption process of Ru complexes in nanoporous ZnO electrodes  

SciTech Connect

Nanostructured ZnO films consisting of 150-nm sized particles were dye-sensitized with different ruthenium complexes. Incident photon-to-current conversion efficiencies (IPCE) were found to be dependent on dye concentration and on residence time of the ZnO film in the dye solution. Results obtained using infrared and Raman spectroscopies together with traditional two-electrode measurements using a sandwich-type cell gave evidence of dye agglomeration in the nanostructured ZnO film. Possible reasons for the agglomeration process in ZnO films are discussed.

Keis, K.; Lindgren, J.; Lindquist, S.E.; Hagfeldt, A.

2000-05-16

292

A study on oxidized glassy carbon sheets for bipolar supercapacitor electrodes  

SciTech Connect

Electrochemical Double Layer Capacitors (EDLC) for high energy and power density applications, based on glassy carbon (GC) electrodes, are being developed in this laboratory. In the context of this project, GC sheets were oxidized and investigated with Small Angle X-ray Scattering (SAXS), Electrochemical Impedance Spectroscopy (EIS) and Nitrogen Gas Adsorption (BET). During oxidation on active film with open pores is built on the surface of the GC. Upon oxidation, the internal volumetric surface area of the active film decreases, whereas the volumetric electrochemical double layer capacitance increases. The authors show that this effect is correlated with the opening, the growth and the coalescence of the pores.

Braun, A.; Baertsch, M.; Geiger, F. [and others

2000-07-01

293

Transfer of highly hydrophilic ions from water to nitrobenzene, studied by three-phase and thin-film modified electrodes.  

PubMed

The study by voltammetry of hydrophilic ion transfers across the interface between an aqueous solution and an immiscible organic solvent is limited by the presence of supporting electrolytes in both phases. Such a study is impossible for ions having a higher affinity for water than ions of the electrolytes. Indirectly, methods based on modified solid electrodes can be used; these are obtained by the deposition of an organic phase containing a molecule having redox properties, the modified electrode being in contact with an aqueous solution of the appropriate electrolyte. The three-phase electrode is very convenient for that purpose. However, this experimental tool also has its own limitation, due mainly to the redox species produced in the organic phase. The oxidized, or reduced, form of the redox molecule must have a very low affinity for water, as otherwise its transfer masks that of the ion under study. Ferrocene is almost useless because of the affinity of the ferrocenium cation for water, decamethylferrocene being a better choice. The present work illustrates how the use of lutetium bisphthalocyanines widely expands the possibilities, as these molecular sandwich complexes can be reduced as well as oxidized, the products of the reactions having a very low affinity for water. This made the determination of the Gibbs energy possible for the transfers of highly hydrophilic ions from water to nitrobenzene: Cl(-) (40 kJ mol(-1)), F(-) (57 kJ mol(-1)), H2PO4(-) (64 kJ mol(-1)). Nothing being really known about the transfer of F(-) or H2PO4(-) from water to organic solvents, these are the first values ever published. H(+), OH(-), and HSO4(-) have also been studied, showing that these species, which have a poor affinity for nitrobenzene, are prone to association reactions with the reduced or oxidized forms of the lutetium bisphthalocyanine. PMID:18505272

Charreteur, Kevin; Quentel, François; Elleouet, Catherine; L'Her, Maurice

2008-05-28

294

Study of peptide on-line complexation with transition-metal ions generated from sacrificial electrodes in thin-chip polymer microsprays.  

PubMed

A miniaturized polymer electrospray-type interface is used to study metal-ion chelation with model peptides. Taking advantage of the intrinsic electrochemical behavior of electrospray, a sacrificial electrode is used to generate at the same time electrospray and transition-metal ions coming from the anodic dissolution of the electrode. The microspray interface provides enhanced mass transport due to its small dimensions, increasing the yield of possible reactions, in particular complex formation. Transition-metal electrodes, e.g. copper, zinc, nickel, iron and silver, are used to obtain on-line complexation with model peptides. It is demonstrated that the use of in-reservoir sacrificial electrodes is an efficient way to generate metal ions in order to form and study complexes with peptides, avoiding the addition of metallic salts. PMID:15818723

Rohner, Tatiana C; Girault, Hubert H

2005-01-01

295

Analysis of non-point and point source pollution in China: case study in Shima Watershed in Guangdong Province  

NASA Astrophysics Data System (ADS)

China economy has been rapidly increased since 1978. Rapid economic growth led to fast growth of fertilizer and pesticide consumption. A significant portion of fertilizers and pesticides entered the water and caused water quality degradation. At the same time, rapid economic growth also caused more and more point source pollution discharge into the water. Eutrophication has become a major threat to the water bodies. Worsening environment problems forced governments to take measures to control water pollution. We extracted land cover from Landsat TM images; calculated point source pollution with export coefficient method; then SWAT model was run to simulate non-point source pollution. We found that the annual TP loads from industry pollution into rivers are 115.0 t in the entire watershed. Average annual TP loads from each sub-basin ranged from 0 to 189.4 ton. Higher TP loads of each basin from livestock and human living mainly occurs in the areas where they are far from large towns or cities and the TP loads from industry are relatively low. Mean annual TP loads that delivered to the streams was 246.4 tons and the highest TP loads occurred in north part of this area, and the lowest TP loads is mainly distributed in middle part. Therefore, point source pollution has much high proportion in this area and governments should take measures to control point source pollution.

Fang, Huaiyang; Lu, Qingshui; Gao, Zhiqiang; Shi, Runhe; Gao, Wei

2013-09-01

296

Electrochemical and thermodynamic studies of the electrode materials for lithium ion batteries  

NASA Astrophysics Data System (ADS)

A series of graphite samples were tested for their electrochemical performance as anode material for lithium ion cells. Specially treated natural graphite samples showed good reversible capacities and relatively small irreversible capacity losses. The good performance of these samples can be explained by the low surface area associated with the rounded edges and absence of exfoliation due to the presence of the rhombohedral phase and defects in the grain boundaries. Graphitized cokes showed larger irreversible capacity losses while mesophase carbons showed lower reversible capacity. The treated natural graphite samples, especially LBG25 were found to be high performance, low cost anode materials for the lithium ion cells. The electrochemical and thermal behaviors of the spinels---LiMn 2O4, LiCo1/6Mn11/6O4, LiFe 1/6Mn11/6O4, and LiNi1/6Mn11/6 O4 were studied using electrochemical and thermochemical techniques. The electrochemical techniques included cyclic voltammetry, charge/discharge cycling of 2016 coin cells and diffusion coefficient measurements using Galvanostatic Intermittent Titration Technique. Better capacity retention(GITT) was observed for the substituted spinels (0.11% loss/cycle for LiCo1/6Mn 11/6O4; 0.3% loss/cycle for LiFe1/6Mn11/6 O4; and 0.2% loss/cycle for LiNi1/6Mn11/6 O4) than for the lithium manganese dioxide spinel (1.6% loss/cycle for first 10 cycles, 0.9% loss/cycle for 33 cycles) during 33 cycles. The Differential Scanning Calorimetry (DSC) results showed that the cobalt substituted spinel has better thermal stability than the lithium manganese oxide and other substituted spinels. The thermal profile of LiMn2O4 and LiAl0.17 Mn1.83O3.97S0.03 was measured in an isothermal micro-calorimeter. The heat contributions are discussed in terms of reversible and irreversible heat generation, in combination with the entropy change directly obtained by the dE/dT measurements and the over-potential measurements. The endothermic and exothermic heat profiles observed during the charge and discharge processes are related to the Li insertion/extraction reaction in the spinel host structure for both materials. The reversible heat generation due to the lithium insertion/extraction reaction in the host electrode is estimated on the basis of the cell entropy change. The heat generation calculated from DeltaS and the open circuit potential results is consistent with the heat profile (exothermic/endothermic) generated during the charge/discharge process and with the magnitude of the heat generation from the experimental results obtained from the IMC at a slow charge/discharge rate. The irreversible heat generation dependence on the current rate is discussed at different discharge rates.

Bang, Hyun Joo

297

Adsorption characteristics of arylisocyanide on Au and Pt electrode surfaces: surface-enhanced Raman scattering study.  

PubMed

It is very important to understand metal-molecule interface characteristics for the development of efficient molecular wires in molecular electronics. Because isocyanide is potentially a good alligator clip, we have investigated in this work the adsorption characteristics of 2,6-dimethylphenylisocyanide (DMPI) on Au and Pt electrodes by recording the potential-dependent surface-enhanced Raman scattering (SERS) spectra. First of all, we confirmed that Pt nanoaggregate films were efficient SERS-active substrates, not only in ambient conditions, but also in electrochemical environments. Second, we confirmed that aryl isocyanide should adsorb on Au and Pt by forming exclusively metal-CN bonds, via a pure sigma type interaction in the case of gold compared with a sigma/pi synergistic interaction on Pt. This implies that DMPI should adsorb on Au only via the on-top site, whereas not only the on-top site, but also the 2-fold bridge and 3-fold hollow sites, could be used in the surface adsorption of DMPI on Pt. Despite these differences, DMPI was assumed to possess a vertical orientation with respect to the Au and Pt substrates, irrespective of the potential variation between +0.2 and -0.6 V relative to the Ag/AgCl reference electrode. The latter characteristics of the Au-CN and Pt-CN combinations are presumed to be useful in designing molecular-scale wires. PMID:16471753

Kim, Nam Hoon; Kim, Kwan

2006-02-01

298

Spectroscopic study of the proton dynamics in manganese dioxide electrode materials  

SciTech Connect

Proton or lithium diffusion is a critical electrode process that occurs in manganese dioxide electrode materials during cycling of either aqueous (alkaline) or non-aqueous (lithium) batteries. The structural and electrochemical properties of a number of hydrated alpha-phase manganese dioxide compounds ({alpha}-MnO{sub 2}{lg_bullet}nH{sub 2}O; n{approx}0.2-0.33), the heat-treated products (n{approx}0-0.1), as well as their more stable lithia-doped derivatives, {alpha}-[xLi{sub 2}O]{lg_bullet}MnO{sub 2} (0 {le} x {le} 0.25), have been investigated. Inelastic neutron scattering was used as a means to differentiate and interrogate the key proton or water interactions in these MnO{sub 2} structures. The neutron spectra reveal excitations associated with the hydrogen vibrations centered at 4, 13, 16, 26, 36, 65, 90, 110, 140, 200, 420, and 490 meV in the alpha-phase and 14, 24, 65, 84, 100, 202, and 425 meV in the lithia-doped derivatives. Band assignments were carried out by comparing these frequencies with those reported for structurally similar hydrated {gamma}-MnO{sub 2} compounds and comparison with infrared data.

Johnson, C.S.; Thackeray, M.M.; Nipko, J.C.; Loong, C.K.

1997-10-01

299

Gold electrodes modified with gold nanoparticles and thio compounds for electrochemical sensing of dopamine alone and in presence of potential interferents. A comparative study  

Microsoft Academic Search

Gold electrodes were modified with self assembled layers (SAMs) composed of mercaptopropionic acid, thiodipropionic acid,\\u000a dithiodipropionic acid, cysteamine and gold nanoparticles and used to study the electrooxidation of dopamine (DA) in solution\\u000a at pH 7. SAMs endowed with gold nanoparticles gave the highest catalytic effect. The results showed that such electrodes are\\u000a capable of resolving the oxidation peaks of DA,

Teresa ?uczak; Maria Be?towska-Brzezinska

2011-01-01

300

Cross-sectional study between SF6 and eco-friendly gases on dielectric coated electrodes for real-size gas insulated switchgear  

Microsoft Academic Search

The paper reports a new transversal study of dielectric coating effects on high voltage (HV) electrodes in SF6 and eco-friendly gases like CO2, dry air and N2 for real-size gas insulated switchgear (GIS). From a practical viewpoint, the breakdown electric field (BDE) data of the following test conditions are collected; 1) large effective electrode area over about 5 x 104

Hiroyuki Hama; Shigemitsu Okabe

2012-01-01

301

Comparative study of two- and three-dimensional modeling on arc discharge phenomena inside a thermal plasma torch with hollow electrodes  

Microsoft Academic Search

A comparative study between two- and three-dimensional (2D and 3D) modeling is carried out on arc discharge phenomena inside a thermal plasma torch with hollow electrodes, in order to evaluate the effects of arc root configuration characterized by either 2D annular or 3D highly localized attachment on the electrode surface. For this purpose, a more precise 3D transient model has

Keun Su Kim; Jin Myung Park; Sooseok Choi; Jongin Kim; Sang Hee Hong

2008-01-01

302

In situ Fourier transform infrared spectroscopic studies on a metal complex-immobilized polyaniline\\/Prussian blue-modified electrode and the application to the electroreduction of COâ  

Microsoft Academic Search

In situ Fourier transform infrared spectroscopic studies have been carried out on the nature of a metal complex-immobilized polyaniline (PAn)\\/Prussian blue-modified electrode and on the application of this electrode to the electroreduction of COâ in an aqueous solution. On cathodic polarization, the ring structures of PAn transformed from quinoid to benzenoid states. It was confirmed that the metal complex [1,8-dihydroxynaphthalene-3,6-disulfonato

K. Ogura; M. Nakayama; C. Kusumoto

1996-01-01

303

Optimizing electrode implantation in sacral nerve stimulation—an anatomical cadaver study controlled by a laparoscopic camera  

Microsoft Academic Search

Background and aim  Sacral nerve stimulation is the therapy of choice in patients with neurogenic faecal and urine incontinence, constipation\\u000a and some pelvic pain syndromes. The aim of this study is to determine the best insertion angles of the electrode under laparoscopic\\u000a visualization of the sacral nerves.\\u000a \\u000a \\u000a \\u000a Materials and methods  Five fresh cadaver pelvises were dissected through an anterior approach of the

N. C. Buchs; J.-C. Dembe; J. Robert-Yap; B. Roche; J. Fasel

2008-01-01

304

Evaluating policy and service interventions: framework to guide selection and interpretation of study end points  

Microsoft Academic Search

The effect of many cost effective policy and service interventions cannot be detected at the level of the patient. This new framework could help improve the design (especially choice of primary end point) and interpretation of evaluative studies

Richard J Lilford; Peter J Chilton; Karla Hemming; Alan J Girling; Celia A Taylor; Paul Barach

2010-01-01

305

Gender-specific starting point bias in choice experiments: Evidence from an empirical study  

Microsoft Academic Search

In this paper, we test whether preferences and willingness-to-pay estimates obtained in a Choice Experiment study are susceptible to starting point bias as is often the case in Dichotomous Choice Contingent Valuation studies. On the basis of a multinomial probit model, we find that preferences are indeed susceptible to starting point bias. In a split-sample design our results suggest that

Jacob Ladenburg; Søren Bøye Olsen

2008-01-01

306

A novel approach to surface electromyography: an exploratory study of electrode-pair selection based on signal characteristics  

PubMed Central

A 3?×?4 electrode array was placed over each of seven muscles and surface electromyography (sEMG) data were collected during isometric contractions. For each array, nine bipolar electrode pairs were formed off-line and sEMG parameters were calculated and evaluated based on repeatability across trials and comparison to an anatomically placed electrode pair. The use of time-domain parameters for the selection of an electrode pair from within a grid-like array may improve upon existing electrode placement methodologies.

2012-01-01

307

Nonlinearity of Cardiac Pacemaker Electrodes  

Microsoft Academic Search

Nonlinear properties of electrodes immersed in saline were studied in the time domain and frequency domain. Three electrode materials were tested: platinum-iridium, Elgiloy, and stainless steel. For time domain measurements, current pulses of 1.0 to 2.0 ms duration and varying amplitudes were applied to the electrodes. Frequency domain measurements of polarization impedance were made with an impedance bridge, utilizing sinusoidal

Dov Jaron; Stanley A. Briller; Herman P. Schwan; David B. Geselowitz

1969-01-01

308

Chronically implanted intrafascicular recording electrodes  

Microsoft Academic Search

A newly designed intrafascicular electrode for chronic neural recording was studied by implanting 12 electrodes in the radial\\u000a nerves of 6 cats for 6 months. Action potentials were monitored at specified intervals throughout the experiment. The number\\u000a and size of the signals recorded suggest that this type of electrode provides information that is appropriate for feedback\\u000a control in functional electrical

Todd Lefurge; Eleanor Goodall; Kenneth Horch; Larry Stensaas; Andrew Schoenberg

1991-01-01

309

Cyclic voltammetry at TCNQ and TTF-TCNQ modified platinum electrodes: A study of the glucose oxidase/glucose and galactose oxidase/galactose systems  

SciTech Connect

Recent work has shown that the synthetic metal TTF-TCNQ can be used as an electrode material for the oxidation of enzymes containing the prosthetic group flavin adenine dinucleotide (FAD). This direct electron transfer (direct in the sense that oxygen is not a mediator) between reduced enzyme and electrode, a process which does not occur to any measurable extent at a typical metal electrode, is not very well understood. In the present work, electron transfer between reduced glucose oxidase and TTF-TCNQ is investigated using cyclic voltammetry, and it is also shown that TCNQ itself can mediate this electron transfer between the enzyme and a platinum electrode. In addition to the glucose oxidase studies, cyclic voltammetric experiments have been performed on the galactose oxidase system, which contains a copper redox center rather than FAD. The results of these experiments demonstrate that the catalytic ability of TTF-TCNQ in enzyme-based electrochemical sensors is quite general. 15 refs., 4 figs.

Hale, P.D.; Skotheim, T.A.

1988-01-01

310

Investigation of Zinc Electrodes Relevant to Zinc-Air Batteries.  

National Technical Information Service (NTIS)

The particulate electrode (fluidized bed electrode or moving bed electrode) has been studied to evaluate its possible application to energy storage. The first part of this study is concerned with the effect of current fluctuation on the morphology of zinc...

H. S. Choi

1986-01-01

311

Quantitative structure-reactivity study of electrochemical oxidation of phenolic compounds at the SnO2-based electrode.  

PubMed

In the present study, the electrochemical oxidation of 22 phenolic compounds was systemically examined at the RuO(2)-SnO(2)-Sb(2)O(5) electrode to elucidate the inherent structure-reactivity correlation. The oxidation process was monitored in situ by UV-vis spectroscopy. A variety of substituents (e.g., -CH(3), -NH(2), -Cl, -OH, -COOH, -NO(2), -CHO) were employed in order to cover various possible electronic effects. Our experimental results revealed that the relationship between the Hammett constant and rate constant for the electrochemical oxidation of phenolic compounds at the RuO(2)-SnO(2)-Sb(2)O(5) electrode was different from the results obtained at a platinum electrode. The substituted phenols with electron-withdrawing groups were electrochemically oxidized more rapidly than those with electron-donating groups. To decipher the effects of physiochemical properties on the electrochemical reactivity of phenolic compounds, 140 molecular descriptors were calculated and assessed for each phenolic compound; a quantitative structure property relationship (QSPR) model was developed. Correlations between the rate constants and quantum properties of the phenolic compounds were achieved using partial least-squares (PLS) analysis. The most crucial quantum descriptors responsible for the electrochemical reactivity of phenolic compounds were determined to be E(HOMO), chemical potential, total dipole, quadrupoles, subgraph counts, relative positive charged surface area, and pK(a). The proposed QSPR model was based on the quantum descriptors derived from the whole molecule, providing lucid explanation and effective prediction of the electrochemical reactivity of various phenolic compounds. PMID:22364571

Tian, Min; Thind, Sapanbir S; Simko, Matthew; Gao, Faming; Chen, Aicheng

2012-03-09

312

Os layers spontaneously deposited on the Pt(111) electrode : XPS, STM and GIF-XAS study.  

SciTech Connect

Scanning tunneling microscopy (STM) characterized adlayers of spontaneously deposited osmium on a Pt(111) electrode were investigated using ex-situ X-ray photoemission spectroscopy (XPS) and in-situ grazing incidence fluorescence X-ray absorption spectroscopy (GIF-XAS). After a single spontaneous deposition, monoatomic (or nearly monoatomic) nanoislands of osmium are formed. The island diameter varies from 2 to 5 nm depending on the Os coverage, which in turn is adjusted by varying the concentration of the Os precursor salt (OsCl3) in the deposition bath and/or by the deposition time. XPS reveals three oxidation states: a metallic Os (the 4f7/2 core level binding energy of 50.8 eV), Os(IV) (51.5 eV) and Os(VIII) (52.4 eV). The metallic osmium exists at potentials below 500 mV (vs. RHE) while above 500 mV osmium is oxidized to Os(IV). Electrodissolution of osmium begins above 900 mV and occurs simultaneously with platinum oxidation. At ca. 1200 mV V versus the RHE reference, the oxidation state of some small amounts of osmium that survive dissolution is the Os(VIII). We demonstrate, for the first time, that mixed or odd valencies of osmium exist on the platinum surface at potentials higher that 800 mV. In-situ GIF-XAS measurements of an Os LIII edge also reveal the presence of three Os oxidation states. Namely, below the electrode potential of 400 mV, the X-ray fluorescent energy at maximum absorption is 10.8765 keV, and is characteristic of the metallic Os. In the potential range between 500 and 1000 mV this energy is gradually shifted to higher values, assignable to higher valencies of osmium, like Os(IV). This tendency continues to higher potentials consistent with the third, highly oxidized osmium form present, most likely Os(VIII). The variation of the 'raw edge jump height' of Os with the electrode potential, which is equivalent to a drop in osmium surface concentration, demonstrates that the electrochemical stripping of Os begins below 1.0 V versus RHE, as expected from voltammetry. Also, the observed intensity of the white line of Os in the 100-400 mV region is larger than the value reported for metallic bulk Os. This discrepancy may result from the difference in the electronic properties of the metallic Os layers on Pt(111) and the metallic bulk Os: in the potential region between 100 and 400 mV, the 5d electrons in Os and Pt form a mixed electronic band, and the density of electronic states near the Fermi level, the main factor determining the white line intensity, may not be the same as in metallic bulk. The presented results on osmium adlayers are much more comprehensive than those available in our previous work due to the combined STM, GIF-XAS and XPS investigations. A nearly perfect convergence of the in situ and ex situ data is one of the main research outcomes of this project. Finally, platinum XPS spectra taken in the context of Os electrooxidation from the electrode surface are also presented and conclusions are made, that up to 900 mV platinum remain metallic, irrespective of a significant osmium oxidation on its surface.

Rhee, C. K.; Wakisaka, M.; Tolmachev, Y.; Johnston, C.; Haasch, R.; Attenkofer, K.; Lu, G. Q.; You, H.; Wieckowski, A.; Univ. of Illinois Champaigh-Urbana

2003-01-01

313

MPGD's spatial and energy resolution studies with an adjustable point-like electron source  

NASA Astrophysics Data System (ADS)

Micropattern Gaseous Detectors (MPGD), like Micromegas or GEM, are used or foreseen in particle physics experiments for which a very good spatial resolution is required. We have developed an experimental method to separate the contribution of the transverse diffusion and the multiplication process by varying the number of primary electrons generated by a point-like source. A pulsed nitrogen laser is focused by an optical setup on the drift electrode which is made of a thin metal layer deposited on a quartz lamina. The number of primary electrons can be adjusted from a few to several thousands on a spot whose transverse size is less than 100?m RMS. The detector can be positioned with an accuracy of 1?m by a motorized three-dimensional system. This method was applied to a small Micromegas detector with a gain set between 10 and 2.10 and an injection of 60 2000 photoelectrons. Spatial resolutions as small as 5?m were measured with 2000 primary electrons. An estimation of the upper limit of the relative gain variance can be obtained from the measurements.

Zerguerras, Thomas; Genolini, Bernard; Peyré, Jean; Pouthas, Joël; Lepeltier, Vincent

2007-10-01

314

Study on the sonic point in unsteady shock reflections via numerical flowfield analysis  

NASA Astrophysics Data System (ADS)

A current literature review revealed that unsteady shock reflection is an active research field in terms of the number of still unanswered questions in this area. One of the unresolved aspects of unsteady shock reflection is the relationship between the catch-up and sonic points. In a recent experiment, Skews and Kleine found that the catch-up point is reached at a higher wall angle than the theoretical sonic point predicted by the steady-state two-shock theory. This thesis attempts to shed some light on these matters via numerical flowfield analysis of unsteady shock reflections. Two-dimensional computations are performed using a locally adaptive unstructured unsteady Euler/Navier-Stokes code. At the first stage, a general guideline for numerical modeling of shock wave front structure using the Navier-Stokes equations on adaptive unstructured grid is presented. Obtained results can be directly used for selection of grid resolution required to study shock reflection problems in a viscous flowfields. Then, various techniques for determination of the location of the sonic/catch-up points in unsteady shock reflection based on numerical flowfield analysis are introduced. The results obtained with these techniques regarding the sonic/catch-up points locations are not in agreement with the experimental results of Skews and Kleine. The causes of this disagreement between the experiments and the present CFD study are studied by imitating the experimental technique used for catch-up point determination. It is shown that the reason for this disagreement is that the shock thickness captured in experimental images exceeds the shock physical thickness by a few orders of magnitude, which leads to detection of the catch-up point at higher wall angles. Three flow models are studied to investigate the location of the sonic/catch-up points on a circular cylinder. The first model is based on the Euler (inviscid, non-heat-conducting) equations and an ideal reflecting surface (impermeable wall boundary condition). The computational experiment for this case shows that the sonic and catch-up points are actually the same points, which approach to the theoretical sonic point with grid refinement. The other two models are intend to study the effect of viscosity on the sonic/catch-up points. At first, the ideal reflecting surface (slip boundary condition) is considered. It is shown that for this case the sonic and catch-up points are again the same points, but the viscous effects (finite shock thickness) cause the sonic/catch-up point to be delayed (to occur at lower wall angles) as compared to the two-shock theory predictions. The final model employs the non-slip reflecting surface. Since in this model the flow velocity at the wall is zero, the sonic point cannot be obtained on the reflection surface; however, the catch-up point can be defined and analyzed. The results of the simulations show that even larger delay for the catch-up point is obtained for the viscous case with the non-slip reflecting surface (in the presence of the boundary layer) as compared to the viscous case with the ideal reflecting surfaces.

Hakkaki-Fard, Ali

315

Optimization of selective stimulation parameters for multi-contact electrodes  

PubMed Central

Background Multi-contact stimulating electrodes are gaining acceptance as a means for interfacing with the peripheral nervous system. These electrodes can potentially activate many independent populations of motor units within a single peripheral nerve, but quantifying their recruitment properties and the overlap in stimulation between contacts is difficult and time consuming. Further, current methods for quantifying overlap between contacts are ambiguous and can lead to suboptimal selective stimulation parameters. This study describes a novel method for optimizing stimulation parameters for multi-contact peripheral stimulating electrodes to produce strong, selective muscle contractions. The method is tested with four-contact spiral nerve-cuff electrodes implanted on bilateral femoral nerves of two individuals with spinal cord injury, but it is designed to be extendable to other electrode technologies with higher densities of contacts. Methods To optimize selective stimulation parameters for multi-contact electrodes, first, recruitment and overlap are characterized for all contacts within an electrode. Recruitment is measured with the twitch response to single stimulus pulses, and overlap between pairs of contacts is quantified by the deviation in their combined response from linear addition of individual responses. Simple mathematical models are fit to recruitment and overlap data, and a cost function is defined to maximize recruitment and minimize overlap between all contacts. Results Results are presented for four-contact nerve-cuff electrodes stimulating bilateral femoral nerves of two human subjects with spinal cord injury. Knee extension moments between 11.6 and 43.2 Nm were achieved with selective stimulation through multiple contacts of each nerve-cuff with less than 10% overlap between pairs of contacts. The overlap in stimulation measured in response to selective stimulation parameters was stable at multiple repeated time points after implantation. Conclusions These results suggest that the method described here can provide an automated means of determining stimulus parameters to achieve strong muscle contractions via selective stimulation through multi-contact peripheral nerve electrodes.

2013-01-01

316

Experimental study of a dipole with feed-points displaced transverse to dipole axis†  

Microsoft Academic Search

Experimental investigations are carried out to verify the recently known theoretical properties of a centre-fed dipole antenna with feed-points displaced transverse to its axis (DAFDTA). A comparative study of the theoretical and experimental properties of a DAFDTA for various feed-point displacement R is presented. The experimental set-up and measurement technique are illustrated by schematic diagrams and actual photographs along with

SHIV PRASAD KOSTA

1968-01-01

317

Population study of tender point counts and pain as evidence of fibromyalgia  

Microsoft Academic Search

AbstractObjective: To determine the relation between tender points, complaints of pain, and symptoms of depression, fatigue, and sleep quality in the general population.Design: Two stage cross sectional study with an initial questionnaire about pain to classify those eligible for an examination of tender points.Setting: Two general practices in north west England.Subjects: Stratified random sample of adults from age-sex registers. Of

P Croft; J Schollum; A Silman

1994-01-01

318

First-principles study of native point defects in hafnia and zirconia  

Microsoft Academic Search

A first-principles study of native point defects in hafnia (HfO2) and zirconia (ZrO2) is carried out to identify dominant defects under different oxygen chemical potentials and Fermi levels. Oxygen vacancies and oxygen interstitials in both HfO2 and ZrO2 show negative- U behavior. It is shown that HfO2 is less prone to the formation of oxygen point defects than ZrO2 under

J. X. Zheng; G. Ceder; T. Maxisch; W. K. Chim; W. K. Choi

2007-01-01

319

Ceramic–electrode interaction in PZT and PNN–PZT multilayer piezoelectric ceramics with AG\\/PD 70\\/30 inner electrode  

Microsoft Academic Search

Pb(Zr0.53Ti0.47)O3(PZT) and PbNi1\\/3Nb2\\/3O3-PZT (PNN–PZT) multilayers with Ag\\/Pd 70\\/30 inner electrodes have been studied from the point of view of the ceramic–electrode interaction. PZT multilayers have shown silver free ceramic layers, and no lead has been detected in the electrode after sintering. Silver transport through the ceramic is avoided because of low open porosity–close porosity transition temperature. This transition seems to

A. C Caballero; E Nieto; P Duran; C Moure; M Kosec; Z Samardzija; G Drazic

1997-01-01

320

Prospective randomized open blinded end-point (PROBE) study. A novel design for intervention trials. Prospective Randomized Open Blinded End-Point.  

PubMed

A novel design for intervention studies is presented, the so called PROBE study (Prospective Randomized Open, Blinded End-point). This design is compared to the classical double-blind design. Among the advantages of the PROBE design are lower cost and greater similarity to standard clinical practice, which should make the results more easily applicable in routine medical care. Since end-points are evaluated by a blinded end-point committee it is obvious that there should be no difference between the two types of trials in this regard. PMID:1366259

Hansson, L; Hedner, T; Dahlöf, B

1992-08-01

321

The gold foil electrode in pattern electroretinography  

Microsoft Academic Search

A recent study found that the gold foil electrode produces large pattern electroretinogram amplitudes, but the test-retest reliability was low. In a three-center study, we observed that 90% of 29 patients who were tested with gold foil electrodes used three times appeared to have markedly lower amplitudes than when tested with new electrodes during the same session. Across study centers,

Thomas C. Prager; Antonio M. Fea; William E. Sponsel; F. Craig Schweitzer; Lissa McNulty; Charles A. Garcia

1994-01-01

322

Human Cell-Based Micro Electrode Array Platform for Studying Neurotoxicity  

PubMed Central

At present, most of the neurotoxicological analyses are based on in vitro and in vivo models utilizing animal cells or animal models. In addition, the used in vitro models are mostly based on molecular biological end-point analyses. Thus, for neurotoxicological screening, human cell-based analysis platforms in which the functional neuronal networks responses for various neurotoxicants can be also detected real-time are highly needed. Microelectrode array (MEA) is a method which enables the measurement of functional activity of neuronal cell networks in vitro for long periods of time. Here, we utilize MEA to study the neurotoxicity of methyl mercury chloride (MeHgCl, concentrations 0.5–500?nM) to human embryonic stem cell (hESC)-derived neuronal cell networks exhibiting spontaneous electrical activity. The neuronal cell cultures were matured on MEAs into networks expressing spontaneous spike train-like activity before exposing the cells to MeHgCl for 72?h. MEA measurements were performed acutely and 24, 48, and 72?h after the onset of the exposure. Finally, exposed cells were analyzed with traditional molecular biological methods for cell proliferation, cell survival, and gene and protein expression. Our results show that 500?nM MeHgCl decreases the electrical signaling and alters the pharmacologic response of hESC-derived neuronal networks in delayed manner whereas effects can not be detected with qRT-PCR, immunostainings, or proliferation measurements. Thus, we conclude that human cell-based MEA platform is a sensitive online method for neurotoxicological screening.

Yla-Outinen, Laura; Heikkila, Juha; Skottman, Heli; Suuronen, Riitta; Aanismaa, Riikka; Narkilahti, Susanna

2010-01-01

323

Strain-based in-situ study of anion and cation insertion into porous carbon electrodes with different pore sizes  

SciTech Connect

The expansion of porous carbon electrodes in a room temperature ionic liquid (RTIL) is studied using in-situ atomic force microscopy (AFM). The effect of carbon surface area and pore size/pore size distribution on the observed strain profile and ion kinetics is examined. Also, the influence of potential scan rate on the strain response is investigated. By analyzing the strain data at various potential scan rates information on ion kinetics in the different carbon materials is obtained. Molecular dynamics (MD) simulations are performed to compare with and provide molecular insights into experimental results, which is the first MD work investigating the pressure exerted on porous electrodes under applied potential in a RTIL electrolyte. Using MD, the pressure exerted on the pore wall is calculated as a function of potential/charge for both a micropore (1.2 nm) and a mesopore (7.0 nm). The shape of the calculated pressure profile matches closely with the strain profiles observed experimentally.

Black, Jennifer M [ORNL] [ORNL; Feng, Guang [ORNL] [ORNL; Fulvio, Pasquale F [ORNL] [ORNL; Hillesheim, Patrick C [ORNL] [ORNL; Dai, Sheng [ORNL] [ORNL; Gogotsi, Yury G. [Drexel University] [Drexel University; Cummings, Peter T [ORNL] [ORNL; Kalinin, Sergei V [ORNL] [ORNL; Balke, Nina [ORNL] [ORNL

2013-01-01

324

Electrochemical behavior of sodium azide at Pt and Au electrodes in sodium sulfate electrolyte: A DEMS study  

SciTech Connect

Azides are widely used in chemical technology for a large variety of applications, such as detonators (Pb(N{sub 3}){sub 2}), getters in electric discharge tubes, anticorrosive agents, or additives for the production of foam rubber. The electro-oxidation and -reduction of sodium azide at porous painted platinum and gold electrodes was studied using the multipurpose electrochemical mass spectrometry (MPEMS) which was operated in the differential electrochemical mass spectrometry (DEMS) mode. The platinum electrode was found to be active for electro-oxidation as well as for electroreduction. Above 0.3 V vs. Hg/Hg{sub 2}SO{sub 4}, azide is oxidized to give N{sub 2}, NO, NO{sub 2}, and N{sub 2}O. Reduction of azide takes place below {minus}0.9 V forming N{sub 2}, N{sub 2}H{sub 4}, and possibly NH{sub 3}. In contrast to platinum, gold showed only activity for the electro-oxidation of azide leading to the formation of N{sub 2}, NO, NO{sub 2}, and N{sub 2}O above 0.5 V. Evidence for a reaction without evolution of volatile products was also found taking place above 0.1 V. A reaction mechanism is discussed emphasizing the role of adsorbed hydrogen and oxygen.

Dalmia, A.; Wasmus, S.; Savinell, R.F.; Liu, C.C. [Case Western Reserve Univ., Cleveland, OH (United States)

1995-11-01

325

Study of styrene butadiene rubber and sodium methyl cellulose as binder for negative electrodes in lithium-ion batteries  

Microsoft Academic Search

Graphite and nano-silicon-based negative electrodes in lithium-ion batteries with low binder content were evaluated. The effectiveness of styrene butadiene rubber (SBR) and various types of cellulose containing electrodes were compared to standard electrodes containing PVdF as binder. The cycling performance of lithium-based half cells in EC:DMC (1:1), 1M LiPF6 shows that styrene butadiene rubber (SBR), sodium carboxymethyl cellulose (Na-CMC), or

H. Buqa; M. Holzapfel; F. Krumeich; C. Veit; P. Novák

2006-01-01

326

Electron microscopy study of formation of thick oxide films on Ir and Ru electrodes  

SciTech Connect

The thick (5-60 ..mu..m) oxide films that can be formed electrochemically at Ir and Ru electrodes are examined by scanning and transmission electron microscopy. Their morphologies are discussed in relation to the remarkable reversibility of redox processes associated with the thick films and the enhancement of apparent electrocatalytic effectiveness of the oxide films, which is found for anodic Cl/sub 2/ and O/sub 2/ evolution processes to increasing extents with growth of the oxide film. The latter effects are much larger at Ir than at Ru. This difference is likely to be associated with the different morphologies of electrochemically grown oxide films that are observable on these two metals. In the case of Ir, the apparent enhancement of electrocatalysis for anodic Cl/sub 2/ or O/sub 2/ evolution seems to be associated with development of a hyperextended, microporous, hydrous oxide film that is accessible to H/sub 2/O and Cl/sub -/ ions. Comparisons are made with thermally formed oxide films generated by decomposition of RuCl/sub 3/ coatings.

Birss, V.; Agerstein-Kozlowska, H.; Conway, B.E.; Myers, R.

1984-07-01

327

Young's modulus reconstruction for radio-frequency ablation electrode-induced displacement fields: a feasibility study.  

PubMed

Radio-frequency (RF) ablation is a minimally invasive treatment for tumors in various abdominal organs. It is effective if good tumor localization and intraprocedural monitoring can be done. In this paper, we investigate the feasibility of using an ultrasound-based Young's modulus reconstruction algorithm to image an ablated region whose stiffness is elevated due to tissue coagulation. To obtain controllable tissue deformations for abdominal organs during and/or intermediately after the RF ablation, the proposed modulus imaging method is specifically designed for using tissue deformation fields induced by the RF electrode. We have developed a new scheme under which the reconstruction problem is simplified to a 2-D problem. Based on this scheme, an iterative Young's modulus reconstruction technique with edge-preserving regularization was developed to estimate the Young's modulus distribution. The method was tested in experiments using a tissue-mimicking phantom and on ex vivo bovine liver tissues. Our preliminary results suggest that high contrast modulus images can be successfully reconstructed. In both experiments, the geometries of the reconstructed modulus images of thermal ablation zones match well with the phantom design and the gross pathology image, respectively. PMID:19258195

Jiang, Jingfeng; Varghese, Tomy; Brace, Christopher L; Madsen, Ernest L; Hall, Timothy J; Bharat, Shyam; Hobson, Maritza A; Zagzebski, James A; Lee, Fred T

2009-02-27

328

Preliminary numerical modeling results - cone penetrometer (CPT) tip used as an electrode  

SciTech Connect

Figure 1 shows the resistivity models considered in this study; log10 of the resistivity is shown. The graph on the upper left hand side shows a hypothetical resisitivity well log measured along a well in the upper layered model; 10% Gaussian noise has been added to the well log data. The lower model is identical to the upper one except for one square area located within the second deepest layer. Figure 2 shows the electrode configurations considered. The ''reference'' case (upper frame) considers point electrodes located along the surface and along a vertical borehole. The ''CPT electrode'' case (middle frame) assumes that the CPT tip serves as an electrode that is electrically connected to the push rod; the surface electrodes are used in conjuction with the moving CPT electrode. The ''isolated CPT electrode'' case assumes that the electrode at the CPT tip is electrically isolated from the pushrod. Note that the separate CPT push rods in the middle and lower frames are shown separated to clarify the figure; in reality, there is only one pushrod that is changing length as the probe advances. Figure 3 shows three pole-pole measurement schemes were considered; in all cases, the ''get lost'' electrodes were the leftmost and rightmost surface electrodes. The top frame shows the reference scheme where all surface and borehole electrodes can be used. The middle frame shows two possible configurations available when a CPT mounted electrode is used. Note that only one of the four poles can be located along the borehole at any given time; electrode combinations such as the one depicted in blue (upper frame) are not possible in this case. The bottom frame shows a sample configuration where only the surface electrodes are used. Figure 4 shows the results obtained for the various measurement schemes. The white lines show the outline of the true model (shown in Figure 1, upper frame). The starting initial model for these inversions is based on the electrical resistivity log shown on the upper left. The results in the lower frame show what would be observed if the data collected by the CPT electrode have been corrected for the effects of the push rod. Figure 5 shows the results obtained when the starting initial model is a homogeneous half-space with a resistivity of 20 ohm-m. This figure can be compared with Figure 4 to see the effect that different starting models have on the inversion. Figure 6 shows results that are analogous to those in Figure 4. In this case, the true model is the one shown in the lower frame of Figure 1. Figure 7 compares corrected and uncorrected results. Both results only used data that can be collected when CPT electrodes are used. The top frame shows results when data is collected with point electrodes (no correction used). The bottom frame shows results when data is collected using a CPT electrode; a correction was applied to remove the effects of the electrically conducting pushrod. Figure 8 compares data collected using the CPT electrodes to data collected with point electrode. The blue diamonds represent the uncorrected CPT data and the red squares represent the corrected CPT data. The top frame (electrical gap = 0.0 m) corresponds to the case where the CPT electrode and the pushrod are connected together thorigh the metal. The bottom frame corresponds to the case where the CPT electrode and pushrod are separated by a 1.0 m gap; the electrical connection between rod and electrode is through the soil.

Ramirez, A L

2006-12-19

329

Point prevalence of psychiatric disorders during the second trimester of pregnancy: A population-based study  

Microsoft Academic Search

Objective: This study was undertaken to determine the point prevalence of psychiatric disorders during the second trimester of pregnancy in a population-based sample of pregnant women. Study Design: Participants were 1795 consecutive pregnant women attending routine ultrasound screening at two obstetric clinics in Northern Sweden during 1 year. The Primary Care Evaluation of Mental Disorders (PRIME-MD) was used for evaluating.

Liselott Andersson; Inger Sundström-Poromaa; Marie Bixo; Marianne Wulff; Karin Bondestam; Monica Åström

2003-01-01

330

NRG study of a generalized Anderson impurity model with non Fermi liquid fixed point.  

NASA Astrophysics Data System (ADS)

We study with the Wilson numerical renormalization group method the phase diagram of a twofold orbitally degenerate doubly occupied Anderson impurity model. Strikingly, the model presents a non-trivial fixed point, similar to that of the two-impurity Kondo problem, which separates a Kondo-screened regime from a Kondo-unscreened one. This novel fixed point is even more robust than that, since it can only be destabilized by orbital or gauge symmetry breaking. We calculate the impurity spectral function (DOS) which shows quite an interesting behavior across the fixed point. In the Kondo screened regime and close to the fixed point the DOS displays, riding on top of a broader peak, a very narrow resonance at the Fermi level. The resonance shrinks upon approaching the fixed point, and finally disappears at the fixed point. Beyond that, in the Kondo-unscreened regime, the narrow resonance is now replaced by a narrow pseudogap gradually opening up. The doubly occupied model has electron-hole symmetry; however the novel fixed point exists even without that symmetry. In general the DOS pseudogap in the Kondo-unscreened regime gets partly filled in, but will still pin the chemical potential. While this impurity model is interesting per se, we are pursuing its use as a tool to understand, via Dynamical Mean Field Theory, the behavior of a strongly correlated lattice model close to the Mott transition. We argue that this lattice model should encounter the non-trivial fixed point just before the Mott transition and react to its instability by spontaneous generation of a superconducting order parameter.

de Leo, Lorenzo; Fabrizio, Michele

2004-03-01

331

A theoretical study on native point defects and dopants in cuprous oxide  

NASA Astrophysics Data System (ADS)

We have performed a first-principle study on the electronic structures, atomic configurations, and formation energies of native point defects in cuprous oxide, i.e. vacancies(VCu,VO), interstitials (Cui,Oi) and antisite defects (CuO,OCu) by using Density Function Theory based VASP package with PAW potentials. We have carefully studied the formation of native point defects under different chemical environments and Fermi level positions. We have also calculated the electronic structures of dopants such as F, Cl, N, Ca and Mg in the cuprous oxide crystal. Their formation at different chemical environments and Fermi level positions will be presented as well.

Wang, Weichao; Wu, Dangxin; Zhang, Qiming; Tao, Meng

2007-03-01

332

Lithium-ion drifting: Application to the study of point defects in floating-zone silicon  

SciTech Connect

The use of lithium-ion (Li{sup +}) drifting to study the properties of point defects in p-type Floating-Zone (FZ) silicon crystals is reported. The Li{sup +} drift technique is used to detect the presence of vacancy-related defects (D defects) in certain p-type FZ silicon crystals. SUPREM-IV modeling suggests that the silicon point defect diffusivities are considerably higher than those commonly accepted, but are in reasonable agreement with values recently proposed. These results demonstrate the utility of Li{sup +} drifting in the study of silicon point defect properties in p-type FZ crystals. Finally, a straightforward measurement of the Li{sup +} compensation depth is shown to yield estimates of the vacancy-related defect concentration in p-type FZ crystals.

Walton, J.T.; Wong, Y.K. [Lawrence Berkeley National Lab., CA (United States); Zulehner, W. [Wacker-Siltronic GmbH, Burghausen (Germany)] [and others

1997-04-01

333

Electrical stimulation and electrode properties. Part 2: pure metal electrodes.  

PubMed

Electrical stimulation can cause significant damage to clinical electrodes as well as patient injury. In this study, the effects of stimulation on pure metal electrodes were investigated without the complexities introduced by the multiple elements that make up the clinical electrode. As with the clinical electrodes, there was significant decomposition of pure stainless steel anodes with no associated significant changes in the cathodes when stimulation employed long pulse durations. Effects of stimulation were greater when the anode and cathode were closer under constant voltage stimulation but were distance independent under constant current stimulation. High ionic content of the solution also increased the degree of damage to the anode as did the presence of chloride in the solution. Electrode composition also influenced the amount damage to the anode. Platinum and platinum-iridium electrodes showed no damage with any stimulus while stainless steel showed the lowest resistance to corrosion for direct current (DC) stimulation. Tungsten electrodes behaved very differently than stainless steel, decomposing with pulse stimulation and resisting decomposition during DC stimulation because of the formation of surface protective layers. Because platinum was able to maintain high levels of current over time, prolonged stimulation produced dramatic increases in the temperature of the solution; however, even short periods of stimulation were sufficient to produce dramatic changes in pH in the neighborhood of the electrode. PMID:21313789

Stevenson, Matthew; Baylor, Kelly; Netherton, Brett L; Stecker, Mark M

2010-12-01

334

Study of the optimum level of electrode placement for the evaluation of absolute lung resistivity with the Mk3.5 EIT system.  

PubMed

Inter-subject variability has caused the majority of previous electrical impedance tomography (EIT) techniques to focus on the derivation of relative or difference measures of in vivo tissue resistivity. Implicit in these techniques is the requirement for a reference or previously defined data set. This study assesses the accuracy and optimum electrode placement strategy for a recently developed method which estimates an absolute value of organ resistivity without recourse to a reference data set. Since this measurement of tissue resistivity is absolute, in Ohm metres, it should be possible to use EIT measurements for the objective diagnosis of lung diseases such as pulmonary oedema and emphysema. However, the stability and reproducibility of the method have not yet been investigated fully. To investigate these problems, this study used a Sheffield Mk3.5 system which was configured to operate with eight measurement electrodes. As a result of this study, the absolute resistivity measurement was found to be insensitive to the electrode level between 4 and 5 cm above the xiphoid process. The level of the electrode plane was varied between 2 cm and 7 cm above the xiphoid process. Absolute lung resistivity in 18 normal subjects (age 22.6 +/- 4.9, height 169.1 +/- 5.7 cm, weight 60.6 +/- 4.5 kg, body mass index 21.2 +/- 1.6: mean +/- standard deviation) was measured during both normal and deep breathing for 1 min. Three sets of measurements were made over a period of several days on each of nine of the normal male subjects. No significant differences in absolute lung resistivity were found, either during normal tidal breathing between the electrode levels of 4 and 5 cm (9.3 +/- 2.4 Omega m, 9.6 +/- 1.9 Omega m at 4 and 5 cm, respectively: mean +/- standard deviation) or during deep breathing between the electrode levels of 4 and 5 cm (10.9 +/- 2.9 Omega m and 11.1 +/- 2.3 Omega m, respectively: mean +/- standard deviation). However, the differences in absolute lung resistivity between normal and deep tidal breathing at the same electrode level are significant. No significant difference was found in the coefficient of variation between the electrode levels of 4 and 5 cm (9.5 +/- 3.6%, 8.5 +/- 3.2% at 4 and 5 cm, respectively: mean +/- standard deviation in individual subjects). Therefore, the electrode levels of 4 and 5 cm above the xiphoid process showed reasonable reliability in the measurement of absolute lung resistivity both among individuals and over time. PMID:16636404

Nebuya, S; Noshiro, M; Yonemoto, A; Tateno, S; Brown, B H; Smallwood, R H; Milnes, P

2006-04-20

335

Electrochemically induced surface modifications of boron-doped diamond electrodes: an X-ray photoelectron spectroscopy study  

Microsoft Academic Search

The activity of diamond electrodes depends on the chemical state of the diamond surface, and the present work is focussed on understanding how chemical changes either produced in situ electrochemically, or by ex situ plasma treatments, influence the electrochemical properties. Conductive boron-doped diamond electrodes were produced by depositing adherent boron-doped diamond films on tungsten substrates using a hot filament reactor

Christiaan H. Goeting; Frank Marken; Aurora Gutiérrez-Sosa; Richard G. Compton; John S. Foord

2000-01-01

336

Microgravimetric, rotating ring-disc and voltammetric studies of the underpotential deposition of selenium on polycrystalline platinum electrodes  

Microsoft Academic Search

Selenium underpotential deposition (upd) on platinum electrodes in perchloric acid solutions was analysed by cyclic voltammetry, rotating ring-disc electrode, and electrochemical quartz crystal microbalance techniques. From the results obtained for Se upd on Pt, the presence of two peaks in the positive sweep with a total charge density value of 420 ?Ccm?2 (found after subtraction of the charge density due

Mauro C. Santos; Sergio A. S. Machado

2004-01-01

337

STUDY OF MATERIAL REMOVAL RATE AND ELECTRODE WEAR RATIO FOR MICRO ELECTRICAL DISCHARGE MILLING OF AISI 420 AND STAVAX ESR  

Microsoft Academic Search

This paper investigates micro electrical discharge (ED) milling for AISI 420 and Stavax ESR stainless steel using tungsten carbide electrode. For each of the materials, experiments have been conducted using the full factorial combination of gap voltage, capacitance and feed rate. Two responses material removal rate (MRR) and electrode wear ratio (EWR) are analyzed. Both MRR and EWR are found

Mohammad Yeakub Ali; Ahsan Ali Khan; Munirah Hamzah; Nor Azura Khalid

2009-01-01

338

Electrode/workpiece combinations  

NASA Astrophysics Data System (ADS)

Of the many machine tool operations available in the shop today, plunge cut Electrical Discharge Machining (EDM) has become an increasingly useful method of materials fabrication. It is a necessary tool for the research and development type of work performed at the Lawrence Livermore National Laboratory (LLNL). With advancing technology, plunge cut EDMs are more efficient, faster, have greater accuracy and are able to produce better surface finishes. They have been in the past and will continue to be an important part of the production of quality parts in both the Precision and NC Shop. It should be kept in mind that as a non-traditional machining process, EDMing is a time consuming process that can be a very expensive method of producing parts. For this reason, it must be used in the most efficient manner in order to make it a cost-effective means of fabrication, although technology has advanced to the point of state-of-the-art equipment, there is currently a void in available technical information needed for use with this process. The type of information sought after concerns the area of electrode/workpiece combinations. This is in reference to the task of choosing the correct electrode material for the specific workpiece material encountered. A brief description of the EDM process will help in understanding the electrode/workpiece relationship.

Benedict, J. J.

1989-10-01

339

An Empirical Study of MultiPoint Constructive Search for Constraint-Based Scheduling  

Microsoft Academic Search

Multi-point constructive search (MPCS) performs a series of resource-limited backtracking searches where each search be- gins either from an empty solution (as in randomized restart) or from a solution that has been encountered during the search. We perform a systematic study of MPCS to evaluate the performance impact of various parameter settings. Re- sults using job shop scheduling instances with

J. Christopher Beck

2006-01-01

340

X-ray Study on the Disordered Structure above the Ferroelectric Curie Point in Potassium Nitrate  

Microsoft Academic Search

The disordered structure (phase I) above the ferroelectric Curie point (ca. 125°C) in KNO3 was studied by analysing X-ray diffuse scattering. The single crystal was prepared by slow cooling from the melt in a small glass tube which was mounted on the sample holder of a camera. The observed intensity distribution of the diffuse scattering in reciprocal space was characterized

Yasuhiro Shinnaka

1962-01-01

341

Key Points on Implementing Performance Management - Case Study of a Joint Venture in Hunan Province  

Microsoft Academic Search

Performance management as an effective tool plays an important role in the evaluation, encouraging staff, promoting enterprise development, improving the market position of company, enhancing vitality and competitiveness. However, what are the key points on implementing performance management? The author of this paper discussed the problem with a case study of a joint venture electronic enterprise in Hunan Province. Through

Chen Hongming; Bin Yan

2009-01-01

342

A blinded pilot study investigating the use of diagnostic ultrasound for detecting active myofascial trigger points  

Microsoft Academic Search

Myofascial trigger points (MFTPs) have been cited by numerous authors as the cause of local and referred pain which arises from muscle and its surrounding fascia. At present there is no reliable objective test which is capable of determining their presence. It was the purpose of this pilot study to assess the use of diagnostic ultrasound in determining any soft

Jeremy Lewis; Philip Tehan

1999-01-01

343

Analytical effective length study of a flat plate heat pipe using point source approach  

Microsoft Academic Search

An analytical approach is presented to evaluate the effective heat transport length of a flat plate heat pipe with multiple heat sources. In this study, point sources are modeled as the heat input to the heat pipe. The analysis is carried out by a proportioning concept of the heat pipe with reference to the heat source’s position and evaluates the

B. K. Tan; T. N. Wong; K. T. Ooi

2005-01-01

344

Hospital-acquired urinary tract infections in Turkey: a nationwide multicenter point prevalence study  

Microsoft Academic Search

Hospital-acquired urinary tract infection (UTI) is the most common infection acquired in hospitals. The aim of the study was to determine the prevalence of UTIs in Turkey. A nationwide one day point-prevalence survey was conducted. Centers for Diseases Control and Prevention (CDC) standard definitions for nosocomial UTIs were used. Data were collected by detailed uniform questionnaires for each patient with

H. Leblebicioglu; S. Esen

2003-01-01

345

Study of the Magnetic Field Effect on Commercial Thermistors using a Water Triple Point  

Microsoft Academic Search

The effect of a magnetic field on commercial thermistors was precisely studied in detail using the water triple point. A thermistor with a code of 44004 manufactured by YSI Inc. was found to show a small correction. Its orientation effect and sensor dependence was found also to be small. The correction Delta T (mK) against magnetic field B(T) was found

Koichi Nara

2005-01-01

346

Photoelectron spectroscopic studies of polyatomic molecules: Spin-polarized electrons from Td point symmetry group molecules  

Microsoft Academic Search

This paper presents a study of angle- and spin-resolved photoelectron spectroscopy in a randomly oriented nonlinear molecule in the nonrelativistic, electric dipole approximation. The theory formulated in the preceding paper has been used along with the methods of the extended point (or spin-double) group to develop, perhaps in their simplest possible forms, the expressions for the five parameters needed to

N. Chandra

1989-01-01

347

ETHNOGRAPHY: THE CODE OF THE ANALYSIS FROM THE POINT OF VIEW OF SCIENTIFIC STUDIES  

Microsoft Academic Search

The programme of the analysis of ethnography as a scientific and educational discipline from the point of view of scientific studies is examined in the article for the first time, the definition of ethnography is given. Science as an integrated phenomenon emerges at the New time as a result of the separation from Philosophy, it passes several stages, at each

G. P. Pirozhkov

2006-01-01

348

THE STUDY ON HARVESTING ROBOT BY TARGET POINTING METHOD BASED ON IMAGE PROCESSING  

Microsoft Academic Search

Nowadays agricultural robots are the most important technology in Japan. Compare to the industrial robots, agricultural robots are hardly to use because a target is living thing. From this reason, agricultural robot focused on fruit harvesting had been studied. In this paper, the robot system, which makes a robot identifying a target by pointing the position in order to harvest

Masaharu ONJI; Nobutaka ITO; Kouji KITO; Yoshinari MORIO

349

Experimental and theoretical study of concentration distributions in a model pore electrode; Measurement of two-dimensional concentration gradients in a zinc model pore  

Microsoft Academic Search

The optical probe beam deflection technique has been employed to study two-dimensional concentration gradients within the electrolyte of a zinc model pore. This paper reports that the model pore cell constructed for this study retains the small, confined geometry and two-dimensional character of an actual pore within a porous zinc electrode. Refractive index gradients in the direction of the model

J. K. Weaver; F. R. McLarnon; E. J. Cairns

1991-01-01

350

In vivo CH 3(CH 2) 11SAu SAM electrodes in the beating heart: In situ analytical studies relevant to pacemakers and interstitial biosensors  

Microsoft Academic Search

To study in vivo modification of the SAM equivalent circuit when a highly ordered SAM is used as a bioelectrode, dodecanethiolate SAM–Au intramuscular electrodes were studied in living rat heart in a challenging in situ perfused rat model by impedance spectroscopy, cyclic voltammetry, and neutron activation analysis (NAA). The SAM layer experienced disintegration in vivo biological system, as NAA detected

Howard A Chou; Daniel H Zavitz; Marc Ovadia

2003-01-01

351

Inexpensive and Disposable pH Electrodes  

ERIC Educational Resources Information Center

|Inexpensive electrodes for the measurement of pH have been constructed using the ionophore tribenzylamine for sensing H[superscript +] concentrations. Both traditional liquid-membrane electrodes and coated-wire electrodes have been constructed and studied, and both exhibit linear, nearly Nernstian responses to changes in pH. Measurements of pH…

Goldcamp, Michael J.; Conklin, Alfred; Nelson, Kimberly; Marchetti, Jessica; Brashear, Ryan; Epure, Emily

2010-01-01

352

Negative Electrode Composition.  

National Technical Information Service (NTIS)

A secondary electrochemical cell and a negative electrode composition for use therewith comprising a positive electrode containing an active material of a chalcogen or a transition metal chalcogenide, a negative electrode containing a lithium-aluminum all...

T. D. Kaun A. A. Chilenskas

1980-01-01

353

A Theoretical Study of the Two-Dimensional Point Focusing by Two Multilayer Laue Lenses.  

SciTech Connect

Hard x-ray point focusing by two crossed multilayer Laue lenses is studied using a full-wave modeling approach. This study shows that for a small numerical aperture, the two consecutive diffraction processes can be decoupled into two independent ones in respective directions. Using this theoretical tool, we investigated adverse effects of various misalignments on the 2D focus profile and discussed the tolerance to them. We also derived simple expressions that described the required alignment accuracy.

Yan,H.; Maser, J.; Kang, H.C.; Macrader, A.; Stephenson, B.

2008-08-10

354

First-principles study of self-interstitial point defects in BCC metals  

Microsoft Academic Search

We report a study of the energetics of self-interstitial defects in V and Mo based on plane-wave supercell density functional calculations. We use a 128 atom cubic supercell and 2x2x2 k-point grid for BZ sampling, which we found to be sufficient to obtain accurate results on the basis of a careful convergence study. In our calculations, all the atoms of

Han Seungwu; Zepeda-Ruiza Luis; Car Roberto; Srolovitz David; Ackland Graeme

2002-01-01

355

Study on the service life and deactivation mechanism of Ti\\/SnO 2 Sb electrode by physical and electrochemical methods  

Microsoft Academic Search

The Sb doped tin dioxide electrode (Sb-doped SnO2) inter-layer was prepared using electroposition layer-by-layer onto a titanium plate, and the Sb-doped SnO2 surface catalytic layer (Ti\\/SnO2-Sb) was prepared using thermo-decomposition method. Accelerated service life tests were carried out in 0.5 M H2SO4 solution and 1.0 M NaOH solution, respectively. The deactivation mechanism of the electrodes is studied using oxygen evolution

Hai-Yang Ding; Yu-Jie Feng; Jiang-Wei Lu

2010-01-01

356

A theoretical study of intrinsic point defects and defect clusters in magnesium aluminate spinel  

NASA Astrophysics Data System (ADS)

Point and small cluster defects in magnesium aluminate spinel have been studied from a first principles viewpoint. Typical point defects that occur during collision cascade simulations are cation anti-site defects, which have a small formation energy and are very stable, O and Mg split interstitials and vacancies. Isolated Al interstitials were found to be energetically unfavourable but could occur as part of a split Mg-Al pair or as a three atom-three vacancy Al 'ring' defect, previously observed in collision cascades using empirical potentials. The structure and energetics of the defects were investigated using density functional theory (DFT) and the results compared to simulations using empirical fixed charge potentials. Each point defect was studied in a variety of supercell sizes in order to ensure convergence. It was found that empirical potential simulations significantly overestimate formation energies, but that the type and relative stability of the defects are well predicted by the empirical potentials both for point defects and small defect clusters.

Gilbert, C. A.; Smith, R.; Kenny, S. D.; Murphy, S. T.; Grimes, R. W.; Ball, J. A.

2009-07-01

357

Pain point system scale (PPSS): a method for postoperative pain estimation in retrospective studies  

PubMed Central

Purpose Pain rating scales are widely used for pain assessment. Nevertheless, a new tool is required for pain assessment needs in retrospective studies. Methods The postoperative pain episodes, during the first postoperative day, of three patient groups were analyzed. Each pain episode was assessed by a visual analog scale, numerical rating scale, verbal rating scale, and a new tool – pain point system scale (PPSS) – based on the analgesics administered. The type of analgesic was defined based on the authors’ clinic protocol, patient comorbidities, pain assessment tool scores, and preadministered medications by an artificial neural network system. At each pain episode, each patient was asked to fill the three pain scales. Bartlett’s test and Kaiser–Meyer–Olkin criterion were used to evaluate sample sufficiency. The proper scoring system was defined by varimax rotation. Spearman’s and Pearson’s coefficients assessed PPSS correlation to the known pain scales. Results A total of 262 pain episodes were evaluated in 124 patients. The PPSS scored one point for each dose of paracetamol, three points for each nonsteroidal antiinflammatory drug or codeine, and seven points for each dose of opioids. The correlation between the visual analog scale and PPSS was found to be strong and linear (rho: 0.715; P < 0.001 and Pearson: 0.631; P < 0.001). Conclusion PPSS correlated well with the known pain scale and could be used safely in the evaluation of postoperative pain in retrospective studies.

Gkotsi, Anastasia; Petsas, Dimosthenis; Sakalis, Vasilios; Fotas, Asterios; Triantafyllidis, Argyrios; Vouros, Ioannis; Saridakis, Evangelos; Salpiggidis, Georgios; Papathanasiou, Athanasios

2012-01-01

358

Low resistance electrode construction  

DOEpatents

An electrochemical cell having a cathode and an anode in contact with an electrolyte. Both electrodes or one of them has an electrically conducting non-metal receptacle defining a chamber with a first metal having a melting point in the range of from about room temperature to about 800.degree. C. inside said receptacle chamber. A second metal with a melting point greater than about 800.degree. C. is in contact with the first metal inside the receptacle chamber and extends outside of the receptacle chamber to form a terminal for the anode. The electrolyte may include the oxides, halides or mixtures thereof of one or more of Li, V, U, Al and the lanthanides. Metal may be produced at the cathode during operation of the cell and oxygen or chlorine at the anode.

Redey, Laszlo (Downers Grove, IL); Karell, Eric J. (Woodridge, IL)

2002-01-01

359

Low Resistance Electrode Construction  

DOEpatents

An electrochemical cell having a cathode and an anode in contact with an electrolyte. Both electrodes or one of them has an electrically conducting non-metal receptacle defining a chamber with a first metal having a melting point in the range of from about room temperature to about 800 C inside said receptacle chamber. A second metal with a melting point greater than about 800 C is in contact with the first metal inside the receptacle chamber and extends outside of the receptacle chamber to form a terminal for the anode. The electrolyte may include the oxides, halides or mixtures thereof of one or more of Li, V, U, Al and the lanthanides. Metal may be produced at the cathode during operation of the cell and oxygen or chlorine at the anode.

Redey, Laszlo; Karell, Eric

2000-01-20

360

Electrochemical study of functionalization on the surface of a chitin/platinum-modified glassy carbon paste electrode.  

PubMed

To functionalize chitin surfaces using proteins, we developed a glucose oxidase (GOD)-chitin/platinum-modified glassy carbon paste electrode (GCPE) as a model. In a weakly acidic solution, negatively charged GOD were immobilized by the protonated acetylamide groups on chitin. When the electrode was immersed in a solution containing GOD, the enzyme was readily immobilized due to the electrostatic interaction. In addition, measurements were performed using electrodes made with powders of different sizes because sensor performance depends on the particle sizes of glassy carbon powder. PMID:19907096

Sugawara, Kazuharu; Yugami, Asako; Terui, Norifumi; Kuramitz, Hideki

2009-11-01

361

The ARIES-I high-field-tokamak reactor: Design-point determination and parametric studies  

SciTech Connect

The multi-institutional ARIES study has examined the physics, technology, safety, and economic issues associated with the conceptual design of a tokamak magnetic-fusion reactor. The ARIES-I variant envisions a DT-fueled device based on advanced superconducting coil, blanket, and power-conversion technologies and a modest extrapolation of existing tokamak physics. A comprehensive systems and trade study has been conducted as an integral and ongoing part of the reactor assessment in order to identify an acceptable design point to be subjected to detailed analysis and integration as well as to characterize the ARIES-I operating space. Results of parametric studies leading to the identification of such a design point are presented. 15 refs., 6 figs., 2 tabs.

Miller, R.L.

1989-01-01

362

Electrode-Skin contact impedance: In vivo measurements on an ovine model  

NASA Astrophysics Data System (ADS)

The problem of electrical impedance between the skin and the electrode is an on-going challenge in bio-electronics. This is particularly true in the case of Electrical Impedance Tomography (EIT), which uses a large number of skin-contact electrodes and is very sensitive to noise. In the present article, contact impedance is measured and compared for a range of electrodes placed on the thorax of an ovine model. The study has been approved by the Westmead Hospital Animal Ethics Committee. The electrode models that were employed in the research are Ag/AgCl electrodes (E1), commonly used for ECG and EIT measurements in both humans and animal models, stainless steel crocodile clips (E2), typically used on animal models, and novel multi-point dry electrodes in two modifications: bronze plated (E3) and nickel plated (E4). Further, since the contact impedance is mostly attributed to the acellular outer layer of the skin, in our experiment, we attempted to study the effect of this layer by comparing the results when the skin is intact and when electrodes are introduced underneath the skin through small cuts. This boundary effect was assessed by comparison of measurements obtained during E2 skin surface contact, and sub-cutaneous contact (E5). Twelve gauge intradermal needles were also tested as an electrode (E6). The full impedance spectrum, from 500 Hz to 300 kHz, was recorded, analysed and compared. As expected, the contact impedance in the more invasive cases, i.e the electrodes under the skin, is significantly lower than in the non-invasive cases. At the frequency of 50 kHz which is commonly used in lung EIT acquisition, electrodes E3, E4 and E6 demonstrated contact impedance of less than 200 ?, compared to more than 400 ? measured for electrodes E1, E2 and E5. In conclusion, the novel multipoint electrodes proved to be best suited for EIT purposes, because they are non-invasive and have lower contact impedance than Ag/AgCl and crocodile clips, in both invasive and non-invasive cases. This further prompted us to design a flexible electrode belt using the novel multi-point electrodes for lung EIT on animal models.

Nguyen, D. T.; Kosobrodov, R.; Barry, M. A.; Chik, W.; Jin, C.; Oh, T. I.; Thiagalingam, A.; McEwan, A.

2013-04-01

363

Living electrodes: Tissue engineering the neural interface.  

PubMed

Soft, cell integrated electrode coatings are proposed to address the problem of scar tissue encapsulation of stimulating neuroprosthetics. The aim of these studies was to prove the concept and feasibility of integrating a cell loaded hydrogel with existing electrode coating technologies. Layered conductive hydrogel constructs are embedded with neural cells and shown to both support cell growth and maintain electro activity. The safe charge injection limit of these electrodes was 8 times higher than conventional platinum (Pt) electrodes and the stiffness was four orders of magnitude lower than Pt. Future studies will determine the biological cues required to support stem cell differentiation from the electrode surface. PMID:24111345

Green, Rylie A; Lim, Khoon S; Henderson, William C; Hassarati, Rachelle T; Martens, Penny J; Lovell, Nigel H; Poole-Warren, Laura A

2013-07-01

364

Impedance study of adsorption of iodide ions at Bi(0 0 1) electrode from the aqueous solutions with constant ionic strength  

Microsoft Academic Search

The adsorption of iodide ions from the aqueous solution with constant ionic strength on the Bi(001) single crystal plane electrode has been studied by impedance spectroscopy. The complex impedance plane and Bode plots have been fitted and analyzed, using the non-linear regression analysis method. The probable limiting kinetic steps of the process were obtained and discussed. At moderate ac frequency

L. Siinor; K. Lust; E. Lust

2007-01-01

365

Performance of a co-electrodeposited Pt-Ru electrode for the electro-oxidation of ethanol studied by in situ FTIR spectroscopy  

Microsoft Academic Search

The ethanol electro-oxidation on a co-electrodeposited Pt-Ru catalyst was studied by in situ FTIR spectroscopy. In contrast with the formation of the known acetaldehyde, acetic acid and carbon dioxide reaction products on a Pt catalyst, on the prepared Pt-Ru electrode only carbon dioxide was detected under the same experimental conditions.

José P. I. Souza; Francisco J. Botelho Rabelo; Inês R. de Moraes; Francisco C. Nart

1997-01-01

366

Electrochemical lithiation and passivation mechanisms of iron monosulfide thin film as negative electrode material for lithium-ion batteries studied by surface analytical techniques  

NASA Astrophysics Data System (ADS)

The lithiation/delithiation reaction mechanism of iron monosulfide (troilite Fe(1?x)S, x = 0.07) as negative electrode material for lithium-ion batteries and the electrode passivation induced by reductive decomposition of the electrolyte were studied by combining surface (X-ray photoelectron spectroscopy, XPS, and time-of-flight secondary ion mass spectrometry, ToF-SIMS) and electrochemical analysis (cyclic voltammetry, CV) of thin films grown by thermal sulfidation of metal iron substrate. XPS analysis performed at different stages of the first lithiation/delithiation cycle shows that the reversible formation of metallic iron and lithium sulfide is not solely limited to the principal cathodic/anodic peaks at 1.23/1.89 V and that disulfide products, possibly Li2FeS2, are also formed at lower cathodic potentials. ToF-SIMS depth profiling of the thin film electrode confirms an incomplete process of conversion/deconversion and reveals an expansion/shrinkage of the material induced by electrochemical lithiation/delithiation. The solid electrolyte interphase (SEI) layer formed on the iron monosulfide thin film electrode is mostly composed of Li2CO3 with some presence of ROCO2Li. For the first time, it is shown that the SEI layer thickness varies upon conversion/deconversion, between 9 and 4.5 nm in the lithiated and delithiated states, respectively, on a conversion-type electrode. Moreover, the electrolyte decomposition products penetrate the bulk electrode until the current collector owing to pulverization/cracking caused by expansion and shrinkage of the thin film material upon cycling.

Liao, Feng; ?wiatowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Klein, Lorena H.; Zanna, Sandrine; Marcus, Philippe

2013-10-01

367

Localization of neurosurgically implanted electrodes via photograph-MRI-radiograph coregistration  

PubMed Central

Intracranial electroencephalography (iEEG) is clinically indicated for medically refractory epilepsy and is a promising approach for developing neural prosthetics. These recordings also provide valuable data for cognitive neuroscience research. Accurate localization of iEEG electrodes is essential for evaluating specific brain regions underlying the electrodes that indicate normal or pathological activity, as well as for relating research findings to neuroimaging and lesion studies. However, electrodes are frequently tucked underneath the edge of a craniotomy, inserted via a burr hole, or placed deep within the brain, where their locations cannot be verified visually or with neuronavigational systems. We show that one existing method, registration of postimplant CT with preoperative MRI, can result in errors exceeding 1 cm. We present a novel method for localizing iEEG electrodes using routinely acquired surgical photographs, X-ray radiographs, and magnetic resonance imaging (MRI) scans. Known control points are used to compute projective transforms that link the different image sets, ultimately allowing hidden electrodes to be localized, in addition to refining the location of manually registered visible electrodes. As the technique does not require any calibration between the different image modalities, it can be applied to existing image databases. The final result is a set of electrode positions on the patient’s rendered MRI yielding locations relative to sulcal and gyral landmarks on individual anatomy, as well as MNI coordinates. We demonstrate the results of our method in eight epilepsy patients implanted with electrode grids spanning the left hemisphere.

Dalal, Sarang S.; Edwards, Erik; Kirsch, Heidi E.; Barbaro, Nicholas M.; Knight, Robert T.; Nagarajan, Srikantan S.

2008-01-01

368

Using GENIE to study a tipping point in the climate system.  

PubMed

We have used the Grid ENabled Integrated Earth system modelling framework to study the archetypal example of a tipping point in the climate system; a threshold for the collapse of the Atlantic thermohaline circulation (THC). eScience has been invaluable in this work and we explain how we have made it work for us. Two stable states of the THC have been found to coexist, under the same boundary conditions, in a hierarchy of models. The climate forcing required to collapse the THC and the reversibility or irreversibility of such a collapse depends on uncertain model parameters. Automated methods have been used to assimilate observational data to constrain the pertinent parameters. Anthropogenic climate forcing leads to a robust weakening of the THC and increases the probability of crossing a THC tipping point, but some ensemble members collapse readily, whereas others are extremely resistant. Hence, we test general methods that have been developed to directly diagnose, from time-series data, the proximity of a 'tipping element', such as the THC to a bifurcation point. In a three-dimensional ocean-atmosphere model exhibiting THC hysteresis, despite high variability in the THC driven by the dynamical atmosphere, some early warning of an approaching tipping point appears possible. PMID:19087945

Lenton, Timothy M; Myerscough, Richard J; Marsh, Robert; Livina, Valerie N; Price, Andrew R; Cox, Simon J; Genie Team

2009-03-13

369

Study of Near-Neighbor Structure of Point Defects in ?-FE by Displacement Cascade  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations have been performed to study the primary damage formation in ?-Fe by collision cascades in the recoil energy range 0.5-20 keV. Two near-neighbor analysis methods including the near-neighbor defect density (NPDD) analysis and cluster analysis were introduced to characterize the spatial aggregation of point defects and the morphologies of clusters, respectively. It is found that the NPDD of self-interstitial atom (SIA) and the number of Frenkel pairs show a similar variation trend, while the NPDD of vacancy exhibits a peak at shorter time than that of SIA. Furthermore, we find that the clusters of point defects exist mostly in the form of chainlike structure in the course and the end of cascades, but the proportion of chainlike clusters decreases with increasing the number of point defects included in one cluster. Therefore, the present methods are found to be effective to characterize the aggregation and the near-neighbor structure of point defects by displacement cascades at any time.

Wang, Wei-Lu; Liu, Wei; Wu, Xuebang; Fang, Q. F.; Liu, C. S.; Huang, Qun-Ying; Wu, Y. C.

2012-07-01

370

Point defects in YBa2Cu3O7-x studied using positron annihilation  

NASA Astrophysics Data System (ADS)

Fast neutron irradiation is a powerful technique for introducing additional pinning centers into high temperature superconductors. The spherical defects with sizes of a few nanometers are considered to be effective pinning centers, enhancing Jc. Their morphology is well-known and has already been investigated by several authors in great detail. However, only very little is known about the nature and density of smaller and point defects, which are invisible in transmission electron microscopy. Positron annihilation lifetime spectroscopy was applied to investigate the nature and the concentration of small point-like defects. In this work, the influence of small point defects, such as vacancies and vacancy clusters, on the superconducting properties of YBa2Cu3O7-x bulks was studied; these were introduced by irradiation in the TRIGA Mark II reactor in Vienna. Jc and Tc measurements were performed prior to and after each irradiation step. The samples were irradiated up to a fast neutron ( > 0.1 MeV) fluence of 6 × 1021 m-2. The two kinds of defects—the large collision cascades and the small point-like defects—contribute to the decrease of Tc as well as to the Jc enhancement in astonishingly similar ways.

Chudy, Michal; Eisterer, M.; Weber, H. W.; Veterníková, J.; Sojak, S.; Sluge?, V.

2012-07-01

371

Electrochemical and spontaneous deposition of ruthenium at platinum electrodes for methanol oxidation: an electrochemical quartz crystal microbalance study  

Microsoft Academic Search

PtRu electrodes with Ru surface concentration ranging from 20 to 50% were prepared by electrolysis of Ru(NO)(NO3)3 at a constant potential and\\/or by spontaneous Ru deposition performed at open circuit potential from a RuCl3 solution. The amount of either spontaneously or electrochemically deposited ruthenium on the platinum electrode was determined by means of an electrochemical quartz crystal microbalance (EQCM). The

F. Vigier; F. Gloaguen; J.-M. Léger; C. Lamy

2001-01-01

372

Performance and impedance studies of thin, porous molybdenum and tungsten electrodes for the alkali metal thermoelectric converter  

Microsoft Academic Search

Columnar, porous, magnetron-sputtered molybdenum and tungsten films show optimum performance as alkali metal thermoelectric converter electrodes at thicknesses less than 1.0 micron when used with molybdenum or nickel current collector grids. Power densities of 0.40 W\\/sq cm for 0.5-micron molybdenum films at 1200 K and 0.35 W\\/sq cm for 0.5-micron tungsten films at 1180 K were obtained at electrode maturity

B. L. Wheeler; R. M. Williams; B. Jeffries-Nakamura; J. L. Lamb; M. E. Loveland; C. P. Bankston; T. Cole

1988-01-01

373

Performance and impedance studies of thin, porous molybdenum and tungsten electrodes for the alkali metal thermoelectric converter  

Microsoft Academic Search

Columnar, porous, magnetron-sputtered molybdenum and tungsten films show optinum performance as AMTEC electrodes at thicknesses less than 1.0 µm when used with molybdenum or nickel current collector grids. Power densities of 0.40 W cm-2 for 0.5 µm molybdenum films at 1200 K and 0.35 W cm-2 for 0.5 µm tungsten films at 1180 K were obtained at electrode maturity after

B. L. Wheeler; R. M. Williams; B. Jeffries-Nakamura; J. L. Lamb; M. E. Loveland; C. P. Bankston; T. Cole

1988-01-01

374

Synchrotron x-ray diffraction studies of the structural properties of electrode materials in operating battery cells  

Microsoft Academic Search

Hard x rays from a synchrotron source were utilized in diffraction experiments which probed the bulk of electrode materials while they were operating {ital in} {ital situ} in battery cells. Two technologically relevant electrode materials were examined; an {ital AB}â-type anode in a nickelâmetalâhydride cell and a LiMnâOâ cathode in a Li-ion {open_quote}{open_quote}rocking chair{close_quote}{close_quote} cell. Structural features such as lattice

T. R. Thurston; N. M. Jisrawi; S. Mukerjee; X. Q. Yang; J. McBreen; M. L. Daroux; X. K. Xing

1996-01-01

375

Synchrotron x-ray diffraction studies of the structural properties of electrode materials in operating battery cells  

Microsoft Academic Search

Hard x rays from a synchrotron source were utilized in diffraction experiments which probed the bulk of electrode materials while they were operating insitu in battery cells. Two technologically relevant electrode materials were examined; an AB2-type anode in a nickel–metal–hydride cell and a LiMn2O4 cathode in a Li-ion ‘‘rocking chair’’ cell. Structural features such as lattice expansions and contractions, phase

T. R. Thurston; N. M. Jisrawi; S. Mukerjee; X. Q. Yang; J. McBreen; M. L. Daroux; X. K. Xing

1996-01-01

376

Does a one point sample adequately characterize the lake environment for paleoenvironmental calibration studies?  

Microsoft Academic Search

A major goal of paleolimnological studies is the quantification of past environmental conditions. This is accomplished by\\u000a computing transfer functions relating organism assemblages to environmental factors. The environmental data are typically\\u000a comprised of a point sample of water chemistry and other environmental parameters that are collected at the same time as a\\u000a surface sediment sample. We explore whether the year

J. Bunbury; K. Gajewski

2008-01-01

377

Toxicogenomic Studies of the Rat Brain at an Early Time Point Following Acute Sarin Exposure  

Microsoft Academic Search

We have studied sarin-induced global gene expression patterns at an early time point (2 h: 0.5×LD50) using Affymetrix Rat Neurobiology U34 chips and male Sprague–Dawley rats. A total of 46 genes showed statistically significant alterations from control levels. Three gene categories contained more of the altered genes than any other groups: ion channel (8 genes) and calcium channel and binding proteins

Tirupapuliyur V. Damodaran; Stephen T. Greenfield; Anand G. Patel; Holly K. Dressman; Siomon K. Lin; Mohamed B. Abou-Donia

2006-01-01

378

Dynamic light-scattering study of a diluted polymer blend near its critical point  

NASA Astrophysics Data System (ADS)

The critical dynamics of a moderately-high-molecular-weight polymer blend of polystyrene and polybutadiene diluted in dioctyl phthalate is studied near the consolute point by dynamic light scattering. Fast and slow modes are observed as in previous experiments on a low-molecular-weight binary-polymer-blend melt. The light-scattering data are consistent with a Fisher renormalization of the correlation-length exponent.

Yajima, Hirofumi; Hair, Dennis W.; Nakatani, Alan I.; Douglas, Jack F.; Han, Charles C.

1993-05-01

379

Towards optimal multi-channel EMG electrode configurations in muscle force estimation: a high density EMG study.  

PubMed

Surface EMG is an important tool in biomechanics, kinesiology and neurophysiology. In neurophysiology the concept of high-density EMG (HD-EMG), using two dimensional electrode grids, was developed for the measurement of spatiotemporal activation patterns of the underlying muscle and its motor units (MU). The aim of this paper was to determine, with the aid of a HD-EMG grid, the relative importance of a number of electrode sensor configurations for optimizing muscle force estimation. Sensor configurations are distinguished in two categories. The first category concerns dimensions: the size of a single electrode and the inter electrode distance (IED). The second category concerns the sensor's spatial distribution: the total area from which signals are obtained (collection surface) and the number of electrodes per cm(2) (collection density). Eleven subjects performed isometric arm extensions at three elbow angles and three contraction levels. Surface-EMG from the triceps brachii muscle and the external force at the wrist were measured. Compared to a single conventional bipolar electrode pair, the force estimation quality improved by about 30% when using HD-EMG. Among the sensor configurations, the collection surface alone appeared to be responsible for the major part of the EMG based force estimation quality by improving it with 25%. PMID:15642649

Staudenmann, Didier; Kingma, Idsart; Stegeman, Dick F; van Dieën, Jaap H

2004-10-26

380

Fluorescence labeling of colloidal core-shell particles with defined isoelectric points for in vitro studies.  

PubMed

In the light of in vitro nanotoxicological studies fluorescence labeling has become standard for particle localization within the cell environment. However, fluorescent labeling is also known to significantly alter the particle surface chemistry and therefore potentially affect the outcome of cell studies. Hence, fluorescent labeling is ideally carried out without changing, for example, the isoelectric point. A simple and straightforward method for obtaining fluorescently labeled spherical metal oxide particles with well-defined isoelectric points and a narrow size distribution is presented in this study. Spherical amorphous silica (SiO2, 161 nm diameter) particles were used as the substrate material and were coated with silica, alumina (Al2O3), titania (TiO2), or zirconia (ZrO2) using sol-gel chemistry. Fluorescent labeling was achieved by directly embedding rhodamine 6G dye in the coating matrix without affecting the isoelectric point of the metal oxide coatings. The coating quality was confirmed by high resolution transmission electron microscopy, energy filtered transmission electron microscopy and electrochemical characterization. The coatings were proven to be stable for at least 240 h under different pH conditions. The well-defined fluorescent particles can be directly used for biomedical investigations, e.g. elucidation of particle-cell interactions in vitro. PMID:22100347

Daberkow, Timo; Meder, Fabian; Treccani, Laura; Schowalter, Marco; Rosenauer, Andreas; Rezwan, Kurosch

2011-11-12

381

On the relation between DC current locations and an EUV bright point: A case study  

NASA Astrophysics Data System (ADS)

Context: Motion of the photospheric plasma forces the footpoints of magnetic flux tubes to move. This can give rise to electric currents in the solar atmosphere. The dissipation of these electric currents and the consequent heating of the solar plasma may be responsible for the formation of Extreme-UltraViolet (EUV) and X-ray bright points. Earlier bright point models usually consider either the emergence or the canceling of photospheric magnetic features as being responsible for reconnection causing the bright point. Aims: We investigate the consequences of different patterns of horizontal photospheric plasma motion for the generation of electric currents in the solar atmosphere and locate them with respect to an observed EUV bright point. The goal is to find out whether these currents might be responsible for the heating of bright points. Methods: To perform this study we use a “data driven” three dimensional magnetohydrodynamic model. The model solves an appropriate set of magnetohydrodynamic equations and uses, as initial condition, the magnetic field extrapolated from the line-of-sight component of the photospheric magnetic field observed by MDI/SoHO and the height-stratified, equilibrium density and temperature of the solar corona. We apply different patterns of horizontal photospheric plasma motion, derived from the temporal evolution of the photospheric magnetic structures in the course of the bright point lifetime, as boundary conditions of the model. Results: All applied patterns of horizontal photospheric plasma motion (shearing, convergence and fragmentation) lead to the formation of electric currents in the chromosphere, transition region and corona. Currents do not develop everywhere in the region where the motion is applied but in specific places where the magnetic field connectivity changes significantly. An important result is that the position where the electric currents develop is independent of the motion pattern used as boundary condition of the model. A comparison with data obtained by TRACE in the 1550 Å channel and by the EIT in the 195 Å channel shows that the region where the strongest current concentrations are formed coincides with the region where the EUV bright point appears.

Santos, J. C.; Büchner, J.; Madjarska, M. S.; Alves, M. V.

2008-10-01

382

Partially filled electrodes for digital microfluidic devices  

NASA Astrophysics Data System (ADS)

As digital microfluidics technology evolves, the need for integrating additional elements (e.g., sensing/detection and heating elements) on the electrode increases. Consequently, electrode area for droplet actuation is reduced to create space for accommodating these additional elements, which undesirably affects force generation. Electrodes cannot simply be scaled larger to compensate for this loss of force, as this would also increase droplet volume and thereby compromise the advantages thought in miniaturization. Here, we present a study evaluating, numerically with preliminary experimental verification, different partially filled electrode designs and suggesting designs that combine high actuation forces with a large reduction in electrode area.

Pyne, D. G.; Salman, W. M.; Abdelgawad, M.; Sun, Y.

2013-07-01

383

Ion-Selective Electrodes.  

ERIC Educational Resources Information Center

|Literature on ion-selective electrodes (ISEs) is reviewed in seven sections: books, conferences, reviews; potentiometric membrane electrodes; glass and solid-state membrane electrodes; liquid and polymer membrane ISEs; coated wire electrodes, ion-selective field effect transistors, and microelectrodes; gas sensors and selective bioelectrode…

Arnold, Mark A.; Meyerhoff, Mark E.

1984-01-01

384

Auricular point acupressure for chronic low back pain: a feasibility study for 1-week treatment.  

PubMed

Objectives. The objective of this one-group, repeated-measures design was to explore the acceptance of auricular point acupressure (APA) to reduce chronic low back pain (CLBP) and estimate minimum clinically important differences (MCIDs) for pain intensity change. Methods. Subjects received 7-day APA treatment. After appropriate acupoints were identified, vaccaria seeds were carefully taped onto each selected auricular point for 7-day. The Brief Pain Inventory Short Form (BPI) was used to collect outcome data. Results. A total of 74 subjects participated in the study. Ten subjects dropped out and the retention rate was 87%. Subjects reported a 46% reduction in BPI worst pain, and over 50% reduction in BPI average pain, overall pain severity and pain interference by the end of study, and 62.5% subjects also reported less pain medication use. The MCIDs for the subscale of BPI ranged from .70 to 1.86 points. The percentage improvement of MCIDs from baseline was between 14.5-24.9%. Discussion. APA appears to be highly acceptable to patients with CLBP. A sham group is needed in order to differentiate the true effects of APA from the possible psychological effects of more frequent visits by the auricular therapist and patients' expectation of the APA treatment. PMID:22811745

Yeh, Chao-Hsing; Chien, Lung-Chang; Chiang, Yi-Chien; Huang, Li-Chun

2012-07-01

385

First-principles studies of intrinsic point defects in magnesium silicide  

NASA Astrophysics Data System (ADS)

We have studied intrinsic point defects in magnesium silicide, Mg2Si, by density-functional theory. Evaluating the formation energies of point defects, we show that n-type electric conductivity of Mg2Si originates from formations of positively charged Mg ions at interstitial sites, regardless of the chemical composition in crystal growth. Moreover, we have calculated the Born effective charge tensors and the valence charge density distribution. They show Mg2Si is an ionic crystal composed of Mg2+ and Si4- which have very different ionic radii, 0.6 Å and 2.1 Å, respectively. We have concluded that the unfavorable antisite defect, MgSi, is due to the dissimilar ionic radii.

Kato, Akihiko; Yagi, Takeshi; Fukusako, Naoto

2009-05-01

386

Electrocatalysts and Electrode Design for Bifunctional Oxygen/Air Electrodes  

NASA Astrophysics Data System (ADS)

Electrocatalysts and appropriate electrode designs have been studied with respect to the development of Bifunctional Air/Oxygen Electrode (BAE). Three groups of catalysts have been prepared: (i) CuxCo3-xO4; (ii) thin films of Co-Ni-Te-O and Co-Te-O and (iii) CoxOv/ZrO2 films. Different catalysts deposited on classical and originally designed GDE were compared by their electrochemical performances.

Nikolova, V.; Iliev, P.; Petrov, K.; Vitanov, T.; Zhecheva, E.; Stoyanova, R.; Valov, I.; Stoychev, D.

387

Electrocoagulation studies on the removal of copper from water using mild steel electrode.  

PubMed

This study provides an electrocoagulation process for the removal of copper from water using mild steel and stainless steel as anode and cathode, respectively. The effect of different operating parameters and coexisting ions on the removal efficiency of copperwas investigated. The results showed that the optimum removal efficiency of 97.8% was achieved at a current density of 0.02 A/dm2 and a pH of 7.0. The adsorption of copper, preferably fitting the Langmuir adsorption isotherm, suggests monolayer coverage of adsorbed molecules. First-and second-order rate equations and Elovich and intraparticle diffusion models were applied to study adsorption kinetics. The adsorption process follows the second-order kinetics model with good correlation. Temperature studies showed that adsorption was endothermic and spontaneous in nature. PMID:22755488

Vasudevan, Subramanyan; Lakshmi, Jothinathan; Sozhan, Ganapathy

2012-03-01

388

Activated transport in AMTEC electrodes  

SciTech Connect

Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O'Connor, D.; Kikkert, S.

1992-01-01

389

Activated transport in AMTEC electrodes  

SciTech Connect

Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O`Connor, D.; Kikkert, S.

1992-07-01

390

Activated transport in AMTEC electrodes  

NASA Astrophysics Data System (ADS)

Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of the diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process.

Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; Oconnor, D.; Kikkert, S.

1992-08-01

391

Developmental changes in point-light walker processing during childhood: a two-year follow-up ERP study.  

PubMed

Event-related potentials were measured in twenty-four children aged 6-15 years, at one-year intervals for two years, to investigate developmental changes in each subject's neural response to a point-light walker (PLW) and a scrambled PLW (sPLW) stimulus. One positive peak (P1) and two negative peaks (N1 and N2) were observed in both occipitotemporal regions at approximately 130, 200, and 300-400ms. The amplitude and latency of the P1 component measured by the occipital electrode decreased during development over the first one-year period. Negative amplitudes of both N1 and N2, induced by the PLW stimulus, were significantly larger than those induced by the sPLW stimulus. Moreover, for the P1-N1 amplitude, the values for the eight-year-old children were significantly larger than those for the twelve-year-old children. N1 and N2 latency at certain electrodes decreased with age, but no consistent changes were observed. These results suggest that enhanced electrophysiological responses to PLW can be observed in all age groups, and that the early components were changed even over the course of a single year at the age of twelve. PMID:23376474

Hirai, Masahiro; Watanabe, Shoko; Honda, Yukiko; Kakigi, Ryusuke

2013-01-14

392

A study of positive electrode materials for batteries operating in a halide-aluminate medium  

Microsoft Academic Search

Cathode behavior in halide-aluminate media was studied with attention focused on the oxidation and reduction processes of halide compounds. The cathodes were made from different carbon and graphite intercalation compounds. It is found that in chloride medium the reduction of fixed chlorine proceeds via two steps while in a mixed bromide-chloride medium a single reduction wave is observed. All cathode

S. Maximovitch; M. Levart; M. Fouletier; N. Nguyen; G. Bronoel

1978-01-01

393

Deuterium and lithium-6 MAS NMR studies of manganese oxide electrode materials  

Microsoft Academic Search

Electrolytic manganese dioxide (EMD) is used world wide as the cathode materials in both lithium and alkaline primary (non-rechargeable) batteries. We have developed deuterium and lithium MAS NMR techniques to study EMD and related manganese oxides and hydroxides, where diffraction techniques are of limited value due to a highly defective nature of the structures. Deuterons in EMD, manganite, groutite, and

Younkee Paik

2003-01-01

394

Changes in response to antiaggregatory treatment in patients with myeloproliferative neoplasms: a sequential study using multiple electrode aggregometry.  

PubMed

In the present study, we used multiple electrode aggregometry (MEA) to investigate the response to aspirin and clopidogrel treatment, and its potential changes over a long-time disease course in patients with myeloproliferative neoplasms (MPNs). arachidonic acid (ASPI), ADP, and thrombin receptor activating peptide (TRAP) tests were performed at two timepoints between 32-50 months in 21 patients with MPN and 1-46 months in 29 controls. We further checked the medical records of the participants to identify a potential correlation of changes in the treatment response with clinical events. In MPN, four out of 13 patients treated with 100?mg of aspirin, no patients receiving 50?mg of aspirin, and one out of five clopidogrel-treated patients showed a therapeutic antiplatelet effect. In the subsequent examinations, five patients changed from response to nonresponse or vice versa. Initial nonresponse and changes from an initial response to nonresponse were observed in six patients with thrombotic events. In the controls, 25 out of 26 aspirin-treated patients and two out of three clopidogrel-treated patients showed an initially adequate in-vitro response. Except from one patient changing from initial aspirin nonresponse to response, all controls showed a stable response state. One control with two ischemic strokes showed a nonresponse to clopidogrel. In conclusion, MEA detects the response to antiaggregatory treatment, as well as its changes during the disease course in patients with MPN. An initial or subsequent nonresponse was observed in patients with thrombotic events. PMID:24176950

Robier, Christoph; Stettin, Mariana; Neubauer, Manfred

2013-12-01

395

Structural changes of the KcsA potassium channel upon application of the electrode potential studied by surface-enhanced IR absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Structural changes of the KcsA potassium channel fixed on gold electrode surface in the upright orientation were studied by surface-enhanced IR absorption spectroscopy (SEIRAS). Measurements were performed at neutral pH, where the activation gate is kept closed. Band intensities were enhanced for the asymmetric (1565 cm-1) and symmetric (1405 cm-1) OCO-carboxylate groups at negative electrode potentials in the K+ solution, but not in the Na+ solution. Even for the reverse-oriented channel, the enhanced OCO-carboxylate band was evident at negative potential. When TBA was loaded in the central cavity, the K+-specific OCO band was not elicited. These results indicate that the negative electrode potential renders the local K+ concentration accumulated at the vicinity of the electrode surface, and the KcsA channel bathed in high K+ changes conformation of the selectivity filter from the collapsed to the open, and OCO-carboxylate groups (D80 and E71) in the back of the filter were rearranged.

Yamakata, Akira; Shimizu, Hirofumi; Osawa, Masatoshi; Oiki, Shigetoshi

2013-06-01

396

X-ray absorption spectroscopy studies of nickel oxide thin film electrodes for supercapacitors  

Microsoft Academic Search

Nickel oxide films were synthesized by electrochemical precipitation of Ni(OH)2 followed by heat-treatment in air at various temperatures (200–600°C). Their structure and electrochemical properties were studied by cyclic voltammetry, X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). XRD results showed that the nickel oxide obtained at 250°C or above has a crystalline NiO structure. The specific capacitance of the oxide

Kyung-Wan Nam; Won-Sub Yoon; Kwang-Bum Kim

2002-01-01

397

Electrochemical studies of Pt\\/Ir–IrO 2 electrocatalyst as a bifunctional oxygen electrode  

Microsoft Academic Search

In the present study, Ir nanoparticles are deposited on the surface of IrO2 nanoparticles with microwave-assisted polyol process. Then the obtained Ir–IrO2 nanocomposite is used as a support to prepare Pt\\/Ir–IrO2 nanocomposite, which has been demonstrated as an excellent bifunctional oxygen catalyst for unitized regenerative fuel cell. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM) characterizations

Fan-Dong Kong; Sheng Zhang; Ge-Ping Yin; Zhen-Bo Wang; Chun-Yu Du; Guang-Yu Chen; Na Zhang

398

Influence of potential's electrode selection on physical modeling of time domain induced polarization (TDIP), case studies of homogeneous isotropic medium  

NASA Astrophysics Data System (ADS)

The relationship between metal mineral content and induced polarization response is not well known. Mathematical and physical modeling in laboratory scale was applied to find out those relationship. Their relationship was obtained by curve mathching. The physical modeling data quality was very importand in obtaining the relationship, therefore accurate and precise measurements are needed. Physical modeling data quality depend on the type of electrode, measurement techniques and equipment. Therefore, it is important to know the characteristics of the utilized potential electrode materials. The results show that porouspot is the most excellent potential electrodes used for TDIP physical modeling. The obtained resistivity and chargeability of the TDIP response of the porouspot electrodes and copper electrodes are 16.11 Ohm-m and 0.015 mSec, and 16 Ohm-m and 0.36 mSec, respectively. It is concluded that the groundwater can be used in homogeneous isotropic medium approach and also it is a good method for host medium in physical modeling.

Yatini; Laesanpura, A.

2013-09-01

399

Acupuncture of specific points influences cortical auditory evoked potentials--a volunteer crossover study.  

PubMed

Specificity of acupoints remains a crucial question in acupuncture research. The aim was to investigate whether acupuncture of specific points influences the Cortical Auditory Evoked Potentials (CAEP). Ten healthy volunteers were enrolled in this study according to inclusion criteria. One of 4 acupoints: TH3, GB43 (both claimed as specific for auditory system by Traditional Chinese Medicine) and non-specific points H7 and ST44, was stimulated during one session. Each volunteer received 4 sessions of acupuncture with an interval of 1 week between the sessions. The latencies and amplitudes of CAEP were registered before and after the acupuncture during each session. The mean peak latencies of P2 component decreased after stimulation of TH3 by 11 ms and GB43 by 14 ms whereas the peak latencies of N2 component increased after stimulation of TH3 by 9 ms and GB43 by 4 ms compared to baseline values (p<0.05). The stimulation of H7 and ST44 did not produce any changes. These findings confirm the specificity of acupuncture points TH3 and GB43 in relation to auditory system. PMID:18672740

Lietz, Peggy; Schmidt, Reinhard; Hosemann, Werner; Pavlovic, Dragan; Gizhko, Vasyl; Lehmann, Christian; Wendt, Michael; Usichenko, Taras I

2008-01-01

400

Implantable electrode for chronic recording from skeletal muscle  

Microsoft Academic Search

An implantable electrode has been developed for recording chronically from skeletal muscle, It consists of two Pt-Ir wires embedded on a silicone rubber block. The electrode was implanted on the longissimus thoracis muscle of rabbit. The impedance changes of the implanted electrode that take place over time were studied. After about two months the impedance value of the implanted electrode

R. Munoz; L. Leija; J. Alvarez; P. R. Hernandez; J. L. Reyes

1997-01-01

401

Bifunctional oxygen electrodes  

NASA Astrophysics Data System (ADS)

The objective of the research on bifunctional oxygen electrodes for alkaline electrolytes was to improve significantly both the cathodic and anodic polarization as well as the cycle life of such electrodes. The research has focused on finding high-efficiency, long-life electrocatalysts for O2 reduction and generation and achieving an understanding of the mechanisms of the catalysis. Catalyst systems which have been examined in alkaline electrolytes have included the following:various types of carbons and graphites; chemically-modified carbons and graphites using adsorptive attachment (e.g., various quinones, macrocycles and chemical linkages); silver and various intermetallics; various oxide systems including perovskites, spinels, pyrochlores and other mixed transition metal oxides; transition metal macrocycles including porphyrins, phthalocyanines, naphthalocyanines and tetraazaannulenes; and thermally-treated macrocycles. Mechanistic studies have particularly focused on the reduction of O2 on various carbon/graphite surfaces and the role of the O2(-) radical ion.

Tryk, D.; Aldred, W.; Chen, Z.; Fierro, C.; Hashiguchi, J.; Hossain, M.; Zhang, Z.; Zhao, F.

1985-01-01

402

Satisfaction with the local service point for care: results of an evaluation study  

PubMed Central

Purpose The market of care increases and is characterized by complexity. Therefore, service points, such as the ‘Zentrale Anlaufstelle Pflege (ZAPf)’ in Nuremberg, are helpful for clients to get orientation. The purpose of the presentation is to show the results of an evaluation study about the clients' satisfaction with the offers of ZAPf. Study Satisfaction with service may be measured with the SERVQUAL concept introduced by Parasuraman et al. (1988). They found out five dimensions of quality (tangibles, reliability, responsiveness, assurances and empathy). We took these dimensions in our study. The study focuses on the quality of service and the benefits recognized by clients. In spring 2007, we conducted 67 interviews by phone, based on a half standardized questionnaire. Statistical analysis was conducted using SPSS. Results The clients want to get information about care in general, financial and legal aspects, alternative care arrangement (e.g. ambulant, long-term care) and typical age-related diseases. They show a high satisfaction with the service provided. Their benefits are to get information and advice, to strengthen the ability of decision taking, to cope with changing situations in life, and to develop solutions. Conclusions The results show that the quality of service is on a high level. Critical success factors are the interdisciplinary cooperation at the service point, based on a regularly and open exchange of information. Every member focuses on an optimal individual solution for the client. Local professional service points act as networkers and brokers. They serve not only for the clients' needs but also support the effective and efficient provision of optimized care.

Esslinger, Adelheid Susanne; Macco, Katrin; Schmidt, Katharina

2009-01-01

403

Electrochemical behavior of antioxidants: I. Mechanistic study on electrochemical oxidation of gallic acid in aqueous solutions at glassy-carbon electrode  

Microsoft Academic Search

Mechanism of electrochemical oxidation of gallic acid in aqueous phosphate buffer solutions of different pH’s was studied at glassy-carbon electrode. The study was performed using cyclic, convolution–deconvolution sweep voltammetry, chronoamperometry and chronocoulometry. It gives two irreversible diffusion-controlled cyclic voltammetric waves at the entire range of pH. The electrochemical oxidation mechanism was proposed to be an ECEC-first order mechanism in which

Refat Abdel-Hamid; Emad F. Newair

2011-01-01

404

Denervation point for neuromuscular blockade on lateral pectoral nerves: a cadaver study  

Microsoft Academic Search

Purpose  The objective of our study was to clarify the topography of the medial and lateral pectoral nerves (LPNs) and the vascularity\\u000a in the infraclavicular fossa and to propose an ideal injection point for neuromuscular blockade of the pectoralis major (PM)\\u000a muscle.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  The pectoral muscles and their nerves were examined bilaterally on 10 formalin-fixed cadavers. The PM muscle was dissected\\u000a from

M. Sefa Özel; Leyla Özel; Sema Zer Toros; Tania Marur; Zafer Y?ld?r?m; Erdal Erdo?du; Melih Kara; Izzet M. Titiz

2011-01-01

405

Engine deposit and pour point studies using canola oil as a diesel fuel  

SciTech Connect

Engine tests conducted during previous investigations have established the viability of using canola oil as a substitute for diesel fuel on a short term basis, but also revealed the need to assess possible combustion chamber deposits from long range testing. Low temperature problems in handling vegetable oils has also been recognized as posing a threat to their use in winter operation. This paper reports a procedure involving a direct comparison of running two different fuels in an engine simultaneously to study deposit problems, and also reports on three attempted methods - fuel blending, fuel heating and fuel additives to reduce the pour point of canola oil. 3 figures, 1 table.

Strayer, R.C.; Craig, W.K.; Zoerb, G.C.

1982-01-01

406

Spectrophotometric Calibration of pH Electrodes in Seawater Using Purified m-Cresol Purple  

PubMed Central

This work examines the use of purified meta-cresol purple (mCP) for direct spectrophotometric calibration of glass pH electrodes in seawater. The procedures used in this investigation allow for simple, inexpensive electrode calibrations over salinities of 20–40 and temperatures of 278.15–308.15 K without preparation of synthetic Tris seawater buffers. The optimal pH range is ?7.0–8.1. Spectrophotometric calibrations enable straightforward, quantitative distinctions between Nernstian and non-Nernstian electrode behavior. For the electrodes examined in this study, both types of behavior were observed. Furthermore, calibrations performed in natural seawater allow direct determination of the influence of salinity on electrode performance. The procedures developed in this study account for salinity-induced variations in liquid junction potentials that, if not taken into account, would create pH inconsistencies of 0.028 over a 10-unit change in salinity. Spectrophotometric calibration can also be used to expeditiously determine the intercept potential (i.e., the potential corresponding to pH 0) of an electrode that has reliably demonstrated Nernstian behavior. Titrations to ascertain Nernstian behavior and salinity effects can be undertaken relatively infrequently (?weekly to monthly). One-point determinations of intercept potential should be undertaken frequently (?daily) to monitor for stable electrode behavior and ensure accurate potentiometric pH determinations.

2012-01-01

407

Ion exchanger modified PVC membranes--selectivity studies and response amplification of oxalate and lactate enzyme electrodes.  

PubMed

We report on a novel method of oxidase enzyme electrode response amplification, using unplasticized PVC and plasticized PVC, respectively. The anion exchanger tricaprylylmethylammonium chloride (Aliquat 336s) and hydrophobic isopropylmyristate (IPM) plasticizer have been used together to modify PVC. Resulting structures are anionic substrate selective and hydrogen peroxide impermeable and can be used as outer membranes of a classical dual membrane amperometric enzyme electrode where an oxidase is used to generate H2O2 for electrochemical detection. Their effect on sensor sensitivity and linearity is considered. PMID:9451790

Reddy, S M; Vadgama, P M

1997-01-01

408

Solar energy conversion: photoelectrochemical and electrochemical studies of organic conducting polymer-coated electrodes in aqueous electrolyte  

SciTech Connect

An electrically conducting polymer (polypyrrole) is employed in the stabilization of polycrystalline and single-crystal n-type Si electrodes in an electrochemical photovoltaic cell. The polymer adheres to the polycrystalline n-type Si more strongly than to the single-crystal material. The high capacitance of the polymer is an important factor in determining the ability of the polymer to stabilize the semiconductor. Polypyrrole in conjuction with a noble metal catalyst protects a tantalum electrode against an insulating oxide formation in an aqueous electrolyte under conditions of oxygen evolution.

Frank, A.J.; Cooper, J.; Noufi, R.; Turner, J.A.; Nozik, A.J.

1982-01-01

409

Comparative study of atmospheric pressure low and radio frequency microjet plasmas produced in a single electrode configuration  

SciTech Connect

Microsize jet-type plasmas were generated in a single pin electrode structure source for two separate input frequencies of 50 kHz and 13.56 MHz in the ambient air. The copper pin electrode radius was 360 {mu}m, and it was placed in a Pyrex tube with a radius of 3 mm for helium gas supply. Due to the input frequency difference, the generated plasmas showed distinct discharge characteristics for their plasma physical appearances, electrical properties, gas temperatures, and optical properties. Strengths and weaknesses of both plasmas were discussed for further applications.

Kim, Dan Bee; Rhee, J. K.; Gweon, B.; Moon, S. Y.; Choe, W. [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2007-10-08

410

Which Disposable Chest Electrode?  

PubMed Central

Chest electrodes are preferred to limb electrodes for cardiac monitoring, as limb movements are not restricted and produce less interference of the E.C.G. trace. Eight types of disposable chest electrodes were investigated to compare their performance, skin reactions, cost, ease of application, size, and skin–electrode impedance. Elema-Schonander electrodes were found to be the most efficient and the most expensive. In their application care was required to avoid severe skin reactions. Dracard electrodes were simple to attach, worked well without severe skin reactions, and were cheap. They are recommended for routine use. Smith and Nephew electrodes, a type of “multipoint electrodes” which do not require electrode jelly, frequently produced severe skin reactions, making them unsuitable for monitoring for periods exceeding 12 hours.

Hubner, P. J. B.

1969-01-01

411

High frequency reference electrode  

DOEpatents

A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

Kronberg, J.W.

1994-05-31

412

High frequency reference electrode  

DOEpatents

A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo'' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

Kronberg, J.W.

1991-03-05

413

Local Effects of Biased Electrodes in the Divertor of NSTX  

SciTech Connect

The goal of this paper is to characterize the effects of small non-axisymmetric divertor plate electrodes on the local scrape-off layer plasma. Four small rectangular electrodes were installed into the outer divertor plates of NSTX. When the electrodes were located near the outer divertor strike point and biased positively, there was an increase in the nearby probe currents and probe potentials and an increase in the LiI light emission at the large major radius end of these electrodes. When an electrode located farther outward from the outer divertor strike point was biased positively, there was sometimes a significant decrease in the LiI light emission at the small major radius end of this electrode, but there were no clear effects on the nearby probes. No non-local effects were observed with the biasing of these electrodes.

: S. Zweben, M.D. Campanell, B.C. Lyons, R.J. Maqueda, Y. Raitses, A.L. Roquemore and F. Scotti

2012-05-07

414

High performance cermet electrodes  

DOEpatents

Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

Isenberg, Arnold O. (Forest Hills Boro, PA); Zymboly, Gregory E. (Penn Hills, PA)

1986-01-01

415

Study of the diffusion of points defects in crystalline silicon using the kinetic ART method  

NASA Astrophysics Data System (ADS)

Because of the long-time scale involved, the activated diffusion of point defects is often studied in standard molecular dynamics at high temperatures only, making it more difficult to characterize complex diffusion mechanisms. Here, we turn to the study of point defect diffusion in crystalline silicon using kinetic ART (kART)[1-2], an off-lattice kinetic Monte Carlo method with on-the-fly catalog building based on the activation-relaxation technique (ART nouveau). By generating catalogs of diffusion mechanisms and fully incorporating elastic and off-lattice effects, kART is a unique tool for characterizing this problem. More precisely, using kART with the standard Stillinger-Weber potential we consider the evolution of crystalline cells with 1 to 4 vacancies and 1 to 4 interstitials at various temperatures and to provide a detailed picture of both the atomistic diffusion mechanisms and overall kinetics in addition to identifying special configurations such as a 2-interstitial super-diffuser. [4pt] [1] F. El-Mellouhi, N. Mousseau and L.J. Lewis, Phys. Rev. B. 78, 153202 (2008)[0pt] [2] L. K. Béland, P. Brommer, F. El-Mellouhi, J.-F. Joly and N. Mousseau, Phys. Rev. E 84, 046704 (2011).

Trochet, Mickael; Brommer, Peter; Beland, Laurent-Karim; Joly, Jean-Francois; Mousseau, Normand

2013-03-01

416

Study of the Plasma near the Plasma Electrode by Probes and Photodetachment in ECR-driven Negative Ion Source  

NASA Astrophysics Data System (ADS)

The effect of the plasma electrode bias on the plasma characteristics near the extraction aperture in a large volume hybrid multicusp negative ion source, driven by 2.45 GHz microwaves, is reported. Spatially resolved negative ion and electron density measurements were performed under various pressures (1-4 mTorr) by means of electrostatic probe and photodetachment technique.

Bacal, M.; Svarnas, P.; Béchu, S.; Pelletier, J.

2009-03-01

417

Modeling study of activation and propagation delays during stimulation of peripheral nerve fibers with a tripolar cuff electrode  

Microsoft Academic Search

Computer simulations were performed to investigate the timing of action potential production and propagation in nerve fibers ranging in diameter from 5 to 15 ?m during stimulation with a tripolar cuff electrode. The influence of stimulus pulse amplitude and duration on size selective excitation and blocking was considered. Because the stimulus duration required to produce anodal blocking depends on the

Eleanor V. Goodall; L. Martin Kosterman; Jan Holsheimer; Johannes J. Struijk

1995-01-01

418

Study of the Plasma near the Plasma Electrode by Probes and Photodetachment in ECR-driven Negative Ion Source  

SciTech Connect

The effect of the plasma electrode bias on the plasma characteristics near the extraction aperture in a large volume hybrid multicusp negative ion source, driven by 2.45 GHz microwaves, is reported. Spatially resolved negative ion and electron density measurements were performed under various pressures (1-4 mTorr) by means of electrostatic probe and photodetachment technique.

Bacal, M.; Svarnas, P. [LPTP, UMR CNRS 7648, Ecole Polytechnique, 91128 Palaiseau (France); Bechu, S.; Pelletier, J. [Laboratoire de Physique Subatomique et de Cosmologie, UMR CNRS 5821, 53 rue des Martyrs, 38026 Grenoble (France)

2009-03-12

419

Total-reflection X-ray fluorescence study of electrochemical deposition of metals on a glass-ceramic carbon electrode surface  

NASA Astrophysics Data System (ADS)

The features of electrochemical deposition and co-deposition of copper, cadmium and lead from aqueous solutions on disc glass-ceramic carbon (GCC) electrode surfaces were studied by total-reflection X-ray fluorescence analysis (TXRF). This method was found to be highly sensitive to the varieties of electrodeposit morphology and depth distribution of elements on the electrode surface. It allows identification of the mechanisms of metal nucleation and growth of thin film electrodeposits. The results of the TXRF study are in good agreement with the recent data of a number of spectroscopic and microscopic methods of solid surface analysis. The polished GCC was shown to be an excellent material for preparation of the sample carriers for TXRF analysis.

Alov, N. V.; Oskolok, K. V.; Wittershagen, A.; Mertens, M.; Rittmeyer, C.; Rostam-Khani, P.; Kolbesen, B. O.

2001-11-01

420

Noise characteristics of stainless-steel surface electrodes  

Microsoft Academic Search

Bioelectric events measured with surface electrodes are subject to noise components which may be significant in comparison\\u000a with low-level biological signals such as evoked neuroelectric potentials, and myoelectric potentials. In an effort to better\\u000a understand noise arising from these electrodes, electrode and measurement system noise is modelled. The effect of electrode\\u000a surface area on electrode impedance and noise is studied

D. T. Godin; P. A. Parker; R. N. Scott

1991-01-01

421

Empirical study of unipolar and bipolar configurations using high resolution single multi-walled carbon nanotube electrodes for electrophysiological probing of electrically excitable cells  

Microsoft Academic Search

Identifying the neurophysiological basis underlying learning and memory in the mammalian central nervous system requires the development of biocompatible, high resolution, low electrode impedance electrophysiological probes; however, physically, electrode impedance will always be finite and, at times, large. Herein, we demonstrate through experiments performed on frog sartorius muscle that single multi-walled carbon nanotube electrode (sMWNT electrode) geometry and placement are

Edward D. de Asis Jr.; Joseph Leung; Sally Wood; Cattien V. Nguyen

2010-01-01

422

A study of ignition effects on thruster performance of a multi-electrode capillary discharge using visible emission spectroscopy diagnostics  

NASA Astrophysics Data System (ADS)

This work examined the effect of ignition on thruster performance characteristics of a capillary discharge device. Early tests of the presented device, incorporating an exploding wire ignition, showed a strong dependence on the initial plasma conditions. The literature supported these findings for more basic laboratory capillaries, but the effect on a thruster device was unknown. An in-depth investigation of different ignition systems were conducted for a capillary discharge based pulsed plasma thruster. In addition to conventional wires, capillary discharges were ignited with low pressure gas and several different types of spark igniters. These methods were compared with each other and with newly developed computer models. The viability of a capillary discharge based electrothermal pulsed plasma thruster as an in-space propulsion system was examined. Thruster performance levels, and their ability to fill a desired niche, which has historically shown rather poor efficiencies, have been explored. This work contains a background literature study, experimental setup and testing of a capillary design, and a comparison to performance models created by others. New techniques have been coupled with proven plasma diagnostics to investigate the internal plasma properties of the device. Visible-light spectroscopy techniques were developed to examine the time-resolved electron number densities at the exit. These measurements indicated that there may be a slower rate for recombination than previous expected. Novel thrust stand techniques were demonstrated, measuring thruster performance characteristics with a high degree of accuracy. It was found the ignition method plays a very small role in discharge characteristics. Electrode erosions was investigated and largely eliminated from the device. The research conducted here has not only increased the understanding of ignition effects, but also the basic physics, of capillary devices.

Pancotti, Anthony P.

423

The study of optical feature point imaging gray value automation control method with movement  

Microsoft Academic Search

In order to solve the problem that feature point imaging quality affects the measurement precision of vision system, a method of optical feature point imaging gray value automation control with movement is proposed. The method eliminates the effect of the relative position changes of camera and feature point on imaging gray value by automatic modulating the current in the feature

Changying C. Liu; Qingcheng Huang; Dong Ye; Rensheng Che; Qiaoyu Xu

2005-01-01

424

Coordination of silver(I) at the surface of carbon paste electrodes modified with 2,5,8-trithia[9]- m-cyclophane as studied by cyclic voltammetry  

Microsoft Academic Search

The electrochemical behaviour of silver(I) at carbon paste electrodes (CPE) modified by 2,5,8-trithia[9]-m-cyclophane (TTCP) were studied voltammetrically in aqueous solutions of sodium perchlorate. Up to three cathodic peaks and anodic currents were observed in the cyclic voltammograms at the modified CPE, in contrast to the voltammograms of Ag+ at the unmodified CPE in the presence and in the absence of

K.-H. Lubert; L. Beyer; J. Casabó; C. Pérez-Jiménez; L. Escriche

1999-01-01

425

Degeneration and regeneration in rabbit peripheral nerve with long-term nerve cuff electrode implant: a stereological study of myelinated and unmyelinated axons  

Microsoft Academic Search

Selective and dynamically co-ordinated functional electrical stimulation (FES) of paralysed\\/paretic limbs in upper motor\\u000a neuron lesioned people depends on optimal contact at the neural interface. Implanted nerve cuff electrodes may form a stable\\u000a electrical neural interface, but may also inflict nerve damage. In this study the immediate and long-term effects of cuff\\u000a implantation on the number and sizes of myelinated

Jytte Overgaard Larsen; Morten Thomsen; Morten Haugland; Thomas Sinkjær

1998-01-01

426

Current efficiency studies of the zinc electrowinning process on aluminum rotating cylinder electrode (RCE) in sulfuric acid medium: Influence of different additives  

Microsoft Academic Search

This work studies the effect of three additives, sodium lauryl sulfate (SLS), cetyltrimethylammonium bromide (CTABr) and arabic gum (AG) on zinc electrowinning on aluminum in a solution of 85gL?1 Zn(II) (1.3M) in 108gL?1 H2SO4 (1.1M). The influence of these three additives is analyzed during the different stages of the reduction process using chronopotentiometric techniques on an aluminum rotating disk electrode

Alejandro Recéndiz; Ignacio González; José L. Nava

2007-01-01

427

In situ FTIR spectroscopic studies of the electrooxidation of C 4 alcohol on a platinum electrode in acid solutions Part I. Reaction mechanism of 1-butanol oxidation  

Microsoft Academic Search

The electrooxidation of 1-butanol (1-BL) on Pt electrodes was studied using cyclic voltammetry and in situ FTIR spectroscopy. The results demonstrated that 1-BL can undergo dehydration to form CH3CH2CH ? CH2 in acid solutions. The IR absorption of of the C ? C bond yielded a broad band around 1600 cm?1, which has been determined in solutions prepared using both

Nan-Hai Li; Shi-Gang Sun

1997-01-01

428

Study of the electronic conduction mechanism in Nb-doped SrTiO3 thin films with Ir and Pt electrodes  

Microsoft Academic Search

Strontium titanate (ST) is an attractive material for dynamic random access memory applications. Doping ST with other elements such as Nb has been shown to reduce problems such as frequency dispersion and resistance degradation associated with this material. In this report, we study the electronic conduction mechanism in Nb-doped ST films [Sr(Ti1-xNbxO3)] with Ir and Pt electrodes. Film thicknesses were

Sundararaman Gopalan; Venkat Balu; Jian-Hung Lee; Jeong Hee-Han; Jack C. Lee

2000-01-01

429

Point-contact study of soft magnetic CoSiBFeNb amorphous alloys  

NASA Astrophysics Data System (ADS)

We study magnetotransport in nanoscale point contacts to soft magnetic CoSiBFeNb ribbons. Such ultrasoft amorphous alloys attracted considerable attention previously because they exhibit Giant Magnetoimpedance (GMI) effect - large variations in the electrical impedance as a function of an external magnetic field [see, for instance, M.-H. Phan, H.-X. Peng, Prog. Mater. Sci. 53, 323 (2008) and references therein]. GMI is attributed to the field-induced variations in alloy permeability and has been established through ac measurements on bulk samples which revealed a strong dependence on ac frequency and amplitude but did not show any variations in dc resistance at all. In our experiments, we use nanocontacts to probe magnetotransport in amorphous CoSiBFeNb at the nanoscale. We use point contacts to inject both ac and dc currents into the alloy ribbons prepared by a melt-spinning technique. Measurements with ac currents revealed GMIs similar to those in macroscopic samples. Interestingly, we also observe a dc magnetoresistance which may be attributed to magnetic domain reorientations in a small contact region. Effects of high dc densities on the magnetoresistance are discussed in terms of spin-transfer torque (STT) effect. We thank A. Serebryakov for providing ribbon samples.

Seinige, Heidi; Wang, Cheng; Tsoi, Valerii; Tsoi, Maxim

2013-03-01

430

A randomized clinical trial of auricular point acupressure for chronic low back pain: a feasibility study.  

PubMed

Objectives. This prospective, randomized clinical trial (RCT) was designed to investigate the feasibility and effects of a 4-week auricular point acupressure (APA) for chronic low back pain (CLBP). Methods. Participants were randomized to either true APA (true acupoints with taped seeds on the designated ear points for CLBP) or sham APA (sham acupoints with taped seeds but on different locations than those designated for CLBP). The duration of treatment was four weeks. Participants were assessed before treatment, weekly during treatment, and 1 month following treatment. Results. Participants in the true APA group who completed the 4-week APA treatment had a 70% reduction in worst pain intensity, a 75% reduction in overall pain intensity, and a 42% improvement in disability due to back pain from baseline assessment. The reductions of worst pain and overall pain intensity in the true APA group were statistically greater than participants in the sham group (P < 0.01) at the completion of a 4-week APA and 1 month followup. Discussion. The preliminary findings of this feasibility study showed a reduction in pain intensity and improvement in physical function suggesting that APA may be a promising treatment for patients with CLBP. PMID:23554825

Yeh, Chao Hsing; Chien, Lung Chang; Balaban, Devora; Sponberg, Rebecca; Primavera, Jaclyn; Morone, Natalia E; Glick, Ronald; Albers, Kathryn M; Cohen, Susan M; Ren, Dianxu; Huang, Li Chun; Suen, Lorna Kwai-Ping

2013-02-28

431

Evaluation of titanium mesh electrode using for transcutaneous intrabody communication by tissue-electrode impedance.  

PubMed

We developed a new transcutaneous communication system (TCS) that uses the human body as a conductive medium for monitoring and controlling an artificial heart and other implanted artificial organs in the body. The TCS is able to transmit data between everywhere on the surface of the body and everywhere inside the body, however poor contact between tissue and the electrode influences on communication performance. Thus in this study, we have developed a titanium mesh electrode for the internal transmission electrode. The titanium mesh electrode has advantages of histocompatibility and mechanical stable contact to the tissue by infiltration of the tissue into the titanium mesh like as an extracellular matrix. There titanium mesh electrodes were implanted separately into the dorsal region of the rats under the skin and the electrical performance of the titanium mesh electrode was evaluated by means of measuring the electrode-tissue boundary resistance. In vivo experimental results showed that the titanium mesh electrode had stable mechanical contact to tissue and lower electrode -tissue boundary resistance. In conclusion, the titanium mesh electrode showed excellent histocompatibility it realized stable contact to tissue as anchor, and it had superior electrical property. Thus the titanium mesh electrode is suitable for an internal electrode of the TCS to monitor artificial organs implanted into the body. PMID:24109775

Okamoto, Eiji; Kikuchi, Sakiko; Mitamura, Yoshinori

2013-07-01

432

Reversible Oxygen Electrodes.  

National Technical Information Service (NTIS)

Achievements during the course of the Project have been briefly summarized. A rotating disk electrode with a concentric ring was shown to be a valuable tool in discriminating between possible mechanisms in 02 reduction. On platinum electrodes in highly pu...

M. Genshaw V. Brusic A. Damjanovic

1964-01-01

433

Low resistance fuel electrodes  

DOEpatents

An electrode 6 bonded to a solid, ion conducting electrolyte 5 is made, where the electrode 6 comprises a ceramic metal oxide 18, metal particles 17, and heat stable metal fibers 19, where the metal fibers provide a matrix structure for the electrode. The electrolyte 5 can be bonded to an air electrode cathode 4, to provide an electrochemical cell 2, preferably of tubular design.

Maskalick, Nichols J. (Pittsburgh, PA); Folser, George R. (Lower Burrell, PA)

1989-01-01

434

Electronic properties of 1-4, dicyanobenzene and 1-4, phenylene diisocyanide molecules contacted between Pt and Pd electrodes: First-principles study  

NASA Astrophysics Data System (ADS)

Using first-principles calculations, we study the electronic properties of 1-4, dicyanobenzene and 1-4, phenylene diisocyanide molecules sandwiched between two Pt(111) and Pd(111) electrodes. For these metal-molecule-metal systems, we calculate the total and local density of states and the charge transfers. Our results suggest that the tunneling is the dominant mechanism of charge transport. By inducing a shift of the Fermi level of about 2eV via an additional gate electrode, the electronic transmission could be significantly increased through the metal-1-4, phenylene diisocyanide-metal systems, but a higher voltage would be required in the metal-1-4, dicyanobenzene-metal devices.

Morari, C.; Rignanese, G.-M.; Melinte, S.

2007-09-01

435

Analysis of charge-injection characteristics at electrode-organic interfaces: Case study of transition-metal oxides  

NASA Astrophysics Data System (ADS)

The formation of resistance-free or Ohmic contacts at metal/organic interfaces remains a significant challenge for achieving high-performance organic electronic devices such as organic light-emitting diodes. Several oxides have recently been reported to yield extremely low-voltage devices and thus have excited a renewed interest in developing the next generation of contacting electrodes. In this paper, major metal oxides, CuO, Cu2O , Ni2O3 , Co3O4 , WO3 , MoO3 , V2O5 , and indium tin oxide, have been systematically studied to compare their relative performance as hole injection anodes, as well as to provide an experimental database for theoretical analysis of current-voltage (IV) characteristics with a diverse range of injection barrier heights. Contrary to previous reports in the literature, none of the oxides studied in this work were found to form a true Ohmic contact with commonly used hole transport layers, such as N,N-diphenyl-N, N-bis-1-naphthyl-1-1-biphenyl-4,4-diamine ( ? -NPD). This discrepancy is attributed to incorrect IV data analysis of the quasi-Ohmic injection regime—the region in between space-charge limited current (SCLC) and injection limited current (ILC)—in previous studies. It is found that the quasi-Ohmic regime is much larger (i.e., covers a greater range of injection barrier height) than has previously been expected. A criterion that defines Ohmic, quasi-Ohmic, and injection limited contacts has been quantified based on a time-domain simulation of charge transport across ? -NPD single-carrier devices. This criterion includes the effects of the electric field dependent mobility, organic layer thickness, and charge-injection barrier height. The effects of the built-in potential on the IV characteristics are also evaluated. A barrier-thickness-voltage “phase” diagram that defines the regions of SCLC, quasi-Ohmic, and ILC for ? -NPD is presented.

Wang, Z. B.; Helander, M. G.; Greiner, M. T.; Qiu, J.; Lu, Z. H.

2009-12-01

436

The current distribution and shape change of zinc electrodes in secondary silver-zinc cells  

Microsoft Academic Search

The current and potential distributions of zinc electrodes in secondary zinc-silver oxide cells during cycling were studied using a sectioned electrode technique. The shape change occurring in zinc electrodes resulting from cell cycling was examined. The zinc electrodes used for this study were of a conventional type of design and were fabricated by a slurry paste method. The positive electrodes

S.-P. Poa; C. H. Wu

1978-01-01

437

Multiscale porous fuel cell electrodes  

NASA Astrophysics Data System (ADS)

Porous electrodes are widely used in fuel cells to enhance electrode performance due to their high surface area. Increasingly, such electrodes are designed with both micro-scale and nano-scale features. In the current work, carbon based porous materials have been synthesized and utilized as bioelectrode support for biofuel cells, analysis of such porous electrodes via rotating disk electrode has been enhanced by a numerical model that considers diffusion and convection within porous media. Finally, porous perovskite metal oxide cathodes for solid oxide fuel cell have been modeled to simulate impedance response data obtained from symmetric cells. Carbon fiber microelectrodes (CFME) were fabricated to mimic the microenvironment of carbon fiber paper based porous electrodes. They were also miniature electrodes for small-scale applications. As observed by scanning electron microscopy (SEM), carbon nanotubes (CNTs) formed a homogeneously intertwined matrix. Biocatalysts can fully infiltrate this matrix to form a composite, with a significantly enhanced glucose oxidation current---that is 6.4 fold higher than the bare carbon fiber electrodes. Based on the CNT based porous matrix, polystyrene beads of uniform diameter at 500 nm were used as template to tune the porous structure and enhance biomolecule transport. Focused ion beam (FIB) was used to observe the morphology both at the surface and the cross-section. It has been shown that the template macro-pores enhanced the fuel transport and the current density has been doubled due to the improvement. Like commonly used rotating disk electrode, the porous rotating disk electrode is a system with analytically solved flow field. Although models were proposed previously with first order kinetics and convection as the only mass transport at high rotations, some recent findings indicated that diffusion could play an important role at all disk rotation rates. In the current proposed model, enzymatic kinetics that follow a Ping Pong Bi Bi mechanism was considered, diffusional transport included, and the electrolyte transport of substrate outside the porous media discussed as well. Composite solid oxide fuel cells have good power generation due to enhanced ion conductivity in the cathode achieved by inclusion of high oxygen ion conductivity materials. Impedance spectroscopies of such cathodes were modeled to study the underlying transport and kinetic mechanisms. The effects of electronic conductor loading were studied, including loading values below the percolation threshold. The conductivity and oxygen surface exchange reaction rate were fitted to experimental data and percolation theory was utilized to explain the fitted trends.

Wen, Hao

438

Study of point defects for B2 structures with a {omega}-type martensitic phase  

SciTech Connect

The molecular dynamics method has been used to study the effects of the inheritance from point defects in B2 structures having an {omega}-like martensitic transformation with different final reaction products, For order defects, antistructural atoms, and their simplest complexes it has been shown that in several cases the number of atoms in the defects increases sharply for martensite during the transition to austenite. Here the traction of chemical energy accumulated by the defects grows. A certain type of defect in the B2 structure in martensite corresponds to the appearance of high-energy linear disordered chains in directions of the [111]{sub B2} type. This can play a substantial role in the determine the path of the reverse martensitic transformation.

Zhorovkov, M.F.; Kulagina, V.V. [Tomsk State Univ. (Russian Federation)

1995-12-01

439

Electrodes for Electrochemical Supercapacitors  

Microsoft Academic Search

Manganese dioxide nanoparticles were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors (ES) were fabricated by impregnation of slurries of the manganese dioxide nanoparticles and carbon black into porous nickel foam current collectors. In the composite electrodes, carbon black nanoparticles formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing manganese dioxide and

Gideon Moses Jacob; Quan Min Yang; Igor Zhitomirsky

2009-01-01

440

Electrically conductive diamond electrodes  

DOEpatents

An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

Swain, Greg (East Lansing, MI); Fischer, Anne (Arlington, VA),; Bennett, Jason (Lansing, MI); Lowe, Michael (Holt, MI)

2009-05-19