Note: This page contains sample records for the topic alternating current voltammetry from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Purification of water by electrocoagulation with an alternating asymmetrical current for stripping voltammetry  

SciTech Connect

The influence of the flow velocity and the current density on the degree of purification of water by electrocoagulation with an alternating asymmetrical current has been studied. It has been demonstrated that under optimum conditions at pH/sub c/ 11.0-11.5 the residual metal content in the purified water drops to the level n x 10/sup -4/ g/ml; this allows its use in the practice of stripping voltammetry.

Gorodovykh, V.E.; Kaplin, A.A.; Svishchenko, N.M.; Obraztsov, S.V.

1987-11-20

2

Alternating current scanning electrochemical microscopy with simultaneous fast-scan cyclic voltammetry.  

PubMed

Fast-scan cyclic voltammetry (FSCV) is combined with alternating current scanning electrochemical microscopy (AC-SECM) for simultaneous measurements of impedance and faradaic current. Scan rates of 10-1000 V s(-1) were used for voltammetry, while a high-frequency (100 kHz), low-amplitude (10 mV rms) sine wave was added to the voltammetric waveform for the ac measurement. Both a lock-in amplifier and an analog circuit were used to measure the amplitude of the resultant ac signal. The effect of the added sine wave on the voltammetry at a carbon fiber electrode was investigated and found to have negligible effect. The combined FSCV and ac measurements were used to provide simultaneous chemical and topographical information about a substrate using a single carbon fiber probe. The technique is demonstrated in living cell culture, where cellular respiration and topography were simultaneously imaged without the addition of a redox mediator. This approach promises to be useful for the topographical and multidimensional chemical imaging of substrates. PMID:23025238

Koch, Jason A; Baur, Melinda B; Woodall, Erica L; Baur, John E

2012-10-17

3

Microcomputer-based instrumentation for multi-frequency Fourier transform alternating current (admittance and impedance) voltammetry  

Microsoft Academic Search

Microcomputer-based instrumentation has been developed which enables high quality Fourier transform alternating current admittance and impedance voltammograms to be obtained over a wide range of frequencies and d.c. potentials. A carefully chosen phase-optimised small amplitude alternating potential waveform containing sets of frequencies which avoid harmonic or intermodular interference are periodically superimposed onto a staircase d.c. ramped voltage. Considerable versatility is

Jeno Házì; Darrell M. Elton; W. Alexander Czerwinski; Jörg Schiewe; Victoria A. Vicente-Beckett; Alan M. Bond

1997-01-01

4

Attributes of direct current aperiodic and alternating current harmonic components derived from large amplitude Fourier transformed voltammetry under microfluidic control in a channel electrode.  

PubMed

The flow rate dependencies of the aperiodic direct current (dc) and fundamental to eighth alternating current (ac) harmonic components derived from large-amplitude Fourier transformed ac (FT-ac) voltammetry have been evaluated in a microfluidic flow cell containing a 25 ?m gold microband electrode. For the oxidation of ferrocenemethanol ([FcMeOH]/[FcMeOH](+) process) in aqueous 0.1 M KNO(3) electrolyte, standard "Levich-like" dc behavior is observed for the aperiodic dc component, which enables the diffusion coefficient for FcMeOH to be obtained. In experimental studies, the first and second ac harmonic components contain contributions from the double layer capacitance current, thereby allowing details of the non-Faradaic current to be established. In contrast, the higher order harmonics and dc aperiodic component are essentially devoid of double layer capacitance contributions allowing the faradaic current dependence on flow rate to be studied. Significantly, flow rate independent data conforming to linear diffusion controlled theory are found in the sixth and higher ac harmonics at a frequency of 15 Hz and for all ac harmonics at a frequency of ? 90 Hz. Analysis of FT-ac voltammograms by theory based on stationary microband or planar electrode configurations confirms that stationary microband and planar electrode configurations and experimental data all converge for the higher order harmonics and establishes that the electrode kinetics are very fast (?1 cms(-1)). The ability to locate, from a single experiment, a dc Faradaic component displaying Levich behavior, fundamental and second harmonics that contain details of the double layer capacitance, and Faradaic ac higher order harmonic currents that are devoid of capacitance, independent of the volume flow rate and also conform closely to mass transport by planar diffusion, provides enhanced flexibility in mass transport and electrode kinetic analysis and in understanding the performance of hydrodynamic electrochemical cells and reactors. PMID:22789156

Matthews, Sinéad M; Shiddiky, Muhammad J A; Yunus, Kamran; Elton, Darrell M; Duffy, Noel W; Gu, Yunfeng; Fisher, Adrian C; Bond, Alan M

2012-07-24

5

Direct separation of faradaic and double layer charging current in potential step voltammetry.  

PubMed

Double layer charging current in electrochemical systems has been a challenging problem in the last several decades because it causes interference to the accurate measurement of faradaic current. A method for extracting faradaic current and double layer charging current directly from the measured total current in potential step voltammetry is developed by using iterative target transformation factor analysis (ITTFA). The method constructs initial target vectors based on the theoretical formulae of faradaic and charging current, and then calculates the weights of faradaic and charging current in the measured signal via the iterative transformation of the initial vectors. Therefore, the two currents in one experiment can be obtained simultaneously without any assumption. The potential step voltammetric signals of potassium ferricyanide, copper sulfate and paracetamol were analyzed with the proposed method. The results show that the shape of the obtained voltammogram is an ideal sigmoid curve with horizontal straight baseline and plateaus, and the intensity of the signal is greatly enhanced. Therefore, the method provides a new way to measure the pure faradic current in the potential step voltammetric experiment, and may provide an alternative for improving the sensitivity of quantitative analysis. PMID:24148448

Tu, Jiarun; Cai, Wensheng; Shao, Xueguang

2013-07-24

6

Alternating current conditioner  

SciTech Connect

This patent describes an alternating current conditioner. It comprises a magnetic core having a gap; a primary winding about the core; a secondary winding about the core; a magnetic shunt providing a shunt path for the primary flux and a shunt path for the secondary flux; circuit means for providing an input signal when the rechargeable battery is being charged; a counter means responsive to the input signal which increments a cycle count.

Bobry, H.H.

1992-05-26

7

Current Alternative Engine Fuels  

Microsoft Academic Search

In this study, methyl and ethyl alcohols, hydrogen, biodiesel, boron, natural gas, liquefied petroleum gas, p-series, electricity, and solar fuels were concluded as alternative engine fuels. Alternative engine fuels are competitive fuels to petroleum. These fuels are important because they replace petroleum fuels. There are many benefits the environment, economy and consumers in using alternative fuels.

MUSTAFA BALAT

2005-01-01

8

Alternating to Direct: Rectifying Alternating Current  

NSDL National Science Digital Library

The Materials Science and Technology Teacher's Workshop (MAST) provides this activity for classes learning about diodes and electrical currents. The laboratory illustrates how diodes can be used to rectify alternating current. It uses a galvanometer to determine the direction of current flow when an AC or DC current is applied to the circuit containing a diode in series with a resistor and a galvanometer.The lesson includes step by step directions for the experiment.The activity should require about 20-30 minutes of class time to complete. Discussion questions and teacher notes are included.

2012-12-03

9

The Generation of Alternate Current  

NSDL National Science Digital Library

Created by Terry L.M. Bartelt of Wisconsin Online Resource Center is a learning object lesson of the generation of alternate current. This is a nice brief introduction for those interested in basic electronic theories.

Bartelt, Terry L.

2010-09-24

10

Studies of Alternating Current Corrosion of Iron.  

National Technical Information Service (NTIS)

An analysis of the effects of alternating current on the corrosion of iron is presented. The corrosion efficiency of iron, generation efficiency of hydrogen gas, and polarization characteristics in the alternating current electrolysis of iron in the aqueo...

Y. Torigoe

1972-01-01

11

Stripping Voltammetry  

NASA Astrophysics Data System (ADS)

Electrochemical stripping means the oxidative or reductive removal of atoms, ions, or compounds from an electrode surface (or from the electrode body, as in the case of liquid mercury electrodes with dissolved metals) [1-5]. In general, these atoms, ions, or compounds have been preliminarily immobilized on the surface of an inert electrode (or within it) as the result of a preconcentration step, while the products of the electrochemical stripping will dissolve in the electrolytic solution. Often the product of the electrochemical stripping is identical to the analyte before the preconcentration. However, there are exemptions to these rules. Electroanalytical stripping methods comprise two steps: first, the accumulation of a dissolved analyte onto, or in, the working electrode, and, second, the subsequent stripping of the accumulated substance by a voltammetric [3, 5], potentiometric [6, 7], or coulometric [8] technique. In stripping voltammetry, the condition is that there are two independent linear relationships: the first one between the activity of accumulated substance and the concentration of analyte in the sample, and the second between the maximum stripping current and the accumulated substance activity. Hence, a cumulative linear relationship between the maximum response and the analyte concentration exists. However, the electrode capacity for the analyte accumulation is limited and the condition of linearity is satisfied only well below the electrode saturation. For this reason, stripping voltammetry is used mainly in trace analysis. The limit of detection depends on the factor of proportionality between the activity of the accumulated substance and the bulk concentration of the analyte. This factor is a constant in the case of a chemical accumulation, but for electrochemical accumulation it depends on the electrode potential. The factor of proportionality between the maximum stripping current and the analyte concentration is rarely known exactly. In fact, it is frequently ignored. For the analysis it suffices to establish the linear relationship empirically. The slope of this relationship may vary from one sample to another because of different influences of the matrix. In this case the concentration of the analyte is determined by the method of standard additions [1]. After measuring the response of the sample, the concentration of the analyte is deliberately increased by adding a certain volume of its standard solution. The response is measured again, and this procedure is repeated three or four times. The unknown concentration is determined by extrapolation of the regression line to the concentration axis [9]. However, in many analytical methods, the final measurement is performed in a standard matrix that allows the construction of a calibration plot. Still, the slope of this plot depends on the active area of the working electrode surface. Each solid electrode needs a separate calibration plot, and that plot must be checked from time to time because of possible deterioration of the electrode surface [2].

Lovri?, Milivoj

12

Fault current limiter and alternating current circuit breaker  

DOEpatents

A solid-state circuit breaker and current limiter are disclosed for a load served by an alternating current source having a source impedance, the solid-state circuit breaker and current limiter comprising a thyristor bridge interposed between the alternating current source and the load, the thyristor bridge having four thyristor legs and four nodes, with a first node connected to the alternating current source, and a second node connected to the load. A coil is connected from a third node to a fourth node, the coil having an impedance of a value calculated to limit the current flowing therethrough to a predetermined value. Control means are connected to the thyristor legs for limiting the alternating current flow to the load under fault conditions to a predetermined level, and for gating the thyristor bridge under fault conditions to quickly reduce alternating current flowing therethrough to zero and thereafter to maintain the thyristor bridge in an electrically open condition preventing the alternating current from flowing therethrough for a predetermined period of time. 9 figs.

Boenig, H.J.

1998-03-10

13

Fault current limiter and alternating current circuit breaker  

DOEpatents

A solid-state circuit breaker and current limiter for a load served by an alternating current source having a source impedance, the solid-state circuit breaker and current limiter comprising a thyristor bridge interposed between the alternating current source and the load, the thyristor bridge having four thyristor legs and four nodes, with a first node connected to the alternating current source, and a second node connected to the load. A coil is connected from a third node to a fourth node, the coil having an impedance of a value calculated to limit the current flowing therethrough to a predetermined value. Control means are connected to the thyristor legs for limiting the alternating current flow to the load under fault conditions to a predetermined level, and for gating the thyristor bridge under fault conditions to quickly reduce alternating current flowing therethrough to zero and thereafter to maintain the thyristor bridge in an electrically open condition preventing the alternating current from flowing therethrough for a predetermined period of time.

Boenig, Heinrich J. (Los Alamos, NM)

1998-01-01

14

Radiation from an Alternating Current Nitrogen Arc.  

National Technical Information Service (NTIS)

An experimental investigation of the total power radiated per unit length from a nitrogen arc operating on alternating and direct current is outlined and sample results are given. The measured results include average and instantaneous radiant power, avera...

P. W. Schreiber

1965-01-01

15

ALTERNATING CURRENT ELECTROCOAGULATION FOR SUPERFUND SITE REMEDIATION  

EPA Science Inventory

The technical and economical feasibility of alternating current electrocoagulation (ACE) developed by Electro-Pure Systems, Inc., was evaluated for a 2-year period. CE is an electrochemical technology where highly-charged aluminum polyhydroxide species are introduced into aqueous...

16

Alternating Current Electrocoagulation for Superfund Site Remediation.  

National Technical Information Service (NTIS)

The technical and economical feasibility of alternating current electrocoagulation (ACE) was evaluated for a 2-year period. ACE is an electrochemical technology where highly-charged aluminum polyhydroxide species are introduced into aqueous media for the ...

N. P. Barkley C. W. Farrell T. W. Gardner-Clayson

1993-01-01

17

Nonlinear alternating current responses of dipolar fluids  

Microsoft Academic Search

The frequency-dependent nonlinear dielectric increment of dipolar fluids in nonpolar fluids is often measured by using a stationary relaxation method in which two electric fields are used: The static direct current (dc) field of high strength causing the dielectric nonlinearity, and the probing alternating current (ac) field of low strength and high frequency. When a nonlinear composite is subjected to

J. P. Huang; K. W. Yu; Mikko Karttunen

2004-01-01

18

Boston University Physics Applets: Alternating Current  

NSDL National Science Digital Library

This web page is an interactive physics simulation on alternating current. The user can see how the voltage and current are in phase for a resistor, and offset for capacitors and inductors. The page explains how to calculate root mean square (RMS) values, as well as finding the capacitive and inductive reactance. This item is part of a collection of similar simulation-based student activities.

Duffy, Andrew

2008-06-30

19

Redox magnetohydrodynamics enhancement of stripping voltammetry of lead(II), cadmium(II) and zinc(II) ions using 1,4-benzoquinone as an alternative pumping species.  

PubMed

Differential pulse anodic stripping voltammetry (DPASV) coupled with redox-magnetohydrodynamics (MHD) is used to enhance the anodic stripping voltammetry (ASV) response using a mercury thin film-glassy carbon electrode. The sensitivity increased to at least a factor of two (at 1.2 T) and is facilitated by using 20.0 mmol L(-1) 1,4-benzoquinone as an alternative pumping species to enhance ASV by redox-MHD. The MHD force formed by the cross-product of ion flux with magnetic field induces solution convection during the deposition step, enhancing mass transport of the analytes to the electrode surface and increasing their preconcentrated quantity in the mercury thin film. Therefore, larger ASV peaks and improved sensitivities are obtained, compared with analyses performed without a magnet. The influence of pH, 1,4-benzoquinone concentration, accumulation potential, and time are also investigated. Detection limits of 0.05, 0.09 and 2.2 ng mL(-1) Cd(II), Pb(II) and Zn(II) were established with an accumulation time of 65 s. The method is used for the analysis of Cd(II), Pb(II) and Zn(II) in different water samples, certified reference materials, and saliva samples with satisfactory results. PMID:22116833

Ensafi, Ali A; Nazari, Z; Fritsch, I

2011-11-24

20

Multivariate curve resolution-alternating least squares assisted by voltammetry for simultaneous determination of betaxolol and atenolol using carbon nanotube paste electrode.  

PubMed

In the present work differential pulse voltammetry coupled with multivariate curve resolution-alternating least squares (MCR-ALS) was applied for simultaneous determination of betaxolol (Bet) and atenolol (Ate) in 0.20M Britton-Robinson (B-R) buffer solution at the surface of a multi-walled carbon nanotube modified carbon paste electrode (MWCNT/CPE). Characterization of the modified electrode was carried out by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A strategy based on experimental design was followed. Operating conditions were improved with central composite rotatable design (CCRD) and response surface methodology (RSM), involving several chemical and instrumental parameters. Then second order data were built from variable pulse heights of DPV and after correction in potential shift analyzed by MCR-ALS. Analytical parameters such as linearity, repeatability, and stability were also investigated and a detection limit (DL) of 0.19 and 0.29?M for Bet and Ate was achieved, respectively. The proposed method was successfully applied in simultaneous determining the two analytes in human plasma. PMID:23632433

Khoobi, Asma; Ghoreishi, Sayed Mehdi; Masoum, Saeed; Behpour, Mohsen

2013-04-12

21

Alternating Current Electric Arc Plasma Generators1  

Microsoft Academic Search

The paper is concerned with stationary thermal plasma generators of the alternating current arc. A number of devices with various designs of electrodes (rod and rail) are presented. The basic attention is given to thermal plasma generators with power from 5 to 600 kW optimized for work on oxidizing media (for air the flow rate from 0.5 up to 70

G. Rutberg; A. A. Safronov; A. V. Surov; S. D. Popov

22

Nonlinear alternating current responses of electrorheological solids  

Microsoft Academic Search

When a composite containing nonlinear dielectric particles suspended in a host medium is subjected to a sinusoidal alternating current (ac) electric field, the dielectric response of the composite will generally consist of ac fields at frequencies of higher-order harmonics. For an electrorheological (ER) solid under structure transformations due to external fields, we apply the Ewald-Kornfeld formulation to derive the local

J. P. Huang

2004-01-01

23

Strong-current arc discharges of alternating current  

Microsoft Academic Search

The review of experimental results of strong current (I=10-104 A) quasi-stationary ac discharges in high pressure (P⩾105 Pa) gases is presented. Structure and properties of alternating current arc in vortex, turbulent flows of air, argon, nitrogen, and hydrogen were investigated. The existence of two arc discharge column regimes, contracted and diffusion, has been established. The processes of heat exchange between

Philip G. Rutberg; Aleksei A. Safronov; Vladislav L. Goryachev

1998-01-01

24

Electronic Alternating-Current Power Regulator  

Microsoft Academic Search

The object of this paper is to describe an electronic alternating-current power regulator, which is instantaneous and independent of frequency. The theory and design considerations governing a conventional circuit using gaseous discharge tubes are presented. The effect of the extent of voltage-limiting by the gas tubes on the degree of regulation is discussed. A bridge-type circuit is described and its

L. B. Cherry; R. F. Wild

1945-01-01

25

Alternating current tokamak reactor with long pulses  

Microsoft Academic Search

Alternating current (ac) tokamak operation in the reactor parameter range is studied by considering the volt-second consumption. A simple condition for obtaining ac operation with nearly constant pulse length is given by 1\\/sub rho\\/\\/R\\/sub rho\\/

O. Mitara; S. W. Wolfe; A. Hirose; H. M Skarsgard

1989-01-01

26

Nonlinear Alternating Current Responses of Electrorheological Solids  

Microsoft Academic Search

When a composite containing nonlinear dielectric particles suspended in a\\u000ahost medium is subjected to a sinusoidal alternating current (ac) electric\\u000afield, the dielectric response of the composite will generally consist of ac\\u000afields at frequencies of higher-order harmonics. For an electrorheological (ER)\\u000asolid under structure transformations due to external fields, we apply the\\u000aEwald-Kornfeld formulation to derive the local

J. P. Huang

2005-01-01

27

Detection and assessment of alternating current corrosion  

SciTech Connect

A measuring system to determine the rue peak potential, without ohmic drop error, is described. There is no alternating current (AC)-induced corrosion when the true max. peak potential is below the potential for cathodic protection (CP). Methods are studied to determine the importance of AC corrosion when the potential is higher than the critical potential for CP during a part of the AC period.

Pourbaix, A.; Carpentiers, P.; Gregoor, R.

2000-03-01

28

Ultrafast micropumping by biased alternating current electrokinetics  

NASA Astrophysics Data System (ADS)

This paper reports dramatic improvements in flow rate over conventional alternating current (ac) electrokinetic micropumps by exploiting asymmetry in electric potentials over the electrodes. A micropump consisting of a planar asymmetric electrode array was tested using ac signals with and without a direct current (dc) bias. All experiments were done at 100 kHz Vac. The pumping velocity is much faster with a dc voltage, in some cases by an order of magnitude, reaching a linear velocity of up to 2.5 mm/s with only 5.4 Vrms. The discovery presents an exciting opportunity for microfluidics. Future improvement can be anticipated with additional optimization.

Lian, Meng; Wu, Jie

2009-02-01

29

The effect of alternating current on the electrodeposition of nickel  

Microsoft Academic Search

Summary 1.The effect of alternating current on the electrodeposition of nickel has been studied. It has been shown that, when alternating current of greater than a certain density is superimposed, the deposit is of a coarsely crystalline structure.2.It has been shown that, when alternating current is superimposed, the numer of pores in electrolytic deposits of nickel is reduced. With increase

A. T. Vagramyan; A. A. Sutyagina

1952-01-01

30

Alternating current electrocoagulation for superfund site remediation  

SciTech Connect

The technical and economical feasibility of alternating current electrocoagulation (ACE) was evaluated for a 2-year period. ACE is an electrochemical technology where highly-charged aluminum polyhydroxide species are introduced into aqueous media for the removal of suspended solids, oil droplets, and soluble ionic pollutants. ACE can break stable aqueous colloidal suspensions of up to 10% total solids and stable emulsions containing up to 5% oil. Major operating parameters have been defined for different classes of effluents based on experimental results using complex synthetic soil slurries and metals. Test results indicate that ACE produces aqueous and solid separations comparable to those produced by chemical flocculent additions, but with reduced filtration times and sludge volumes. The technology has application where removal of soluble and suspended pollutants from effluents is required, and in the recovery of fine-grained products from process streams. The technology however, has not yet been demonstrated at full-scale for Superfund site remediation. Summarized are the principal results of the SITE research program and results of ACE treatment on some different classes of industrial effluents, not part of the SITE Program.

Barkley, N.P.; Farrell, C.W.; Gardner-Clayson, T.W.

1993-01-01

31

Alternative pain medicine: Current modalities and principles  

Microsoft Academic Search

Conventional pain medicine does not solve all the problems of chronic pain patients. In this technological era, patients are\\u000a more demanding and in their frustration may seek alternative modalities for managing their chronic pain. Recent studies have\\u000a shown that this tendency may in fact expose patients not only to useless therapies but occasionally harmful ones. Many alternative\\u000a modalities have been

Winston C. V. Parris

1997-01-01

32

Affordable Cyclic Voltammetry  

ERIC Educational Resources Information Center

Cyclic voltammetry is an important component of the undergraduate chemical curriculum. Unfortunately, undergraduate students rarely have the opportunity to conduct experiments in cyclic voltammetry owing to the high cost of potentiostats, which are required to control these experiments. By using MicroLab data acquisition interfaces in conjunction…

Stewart, Greg; Kuntzleman, Thomas S.; Amend, John R.; Collins, Michael J.

2009-01-01

33

Affordable Cyclic Voltammetry  

ERIC Educational Resources Information Center

|Cyclic voltammetry is an important component of the undergraduate chemical curriculum. Unfortunately, undergraduate students rarely have the opportunity to conduct experiments in cyclic voltammetry owing to the high cost of potentiostats, which are required to control these experiments. By using MicroLab data acquisition interfaces in conjunction…

Stewart, Greg; Kuntzleman, Thomas S.; Amend, John R.; Collins, Michael J.

2009-01-01

34

An Alternative Introduction to Maxwell's Displacement Current  

NASA Astrophysics Data System (ADS)

In introductory texts Ampere's law is generally introduced in the steady-current form ? B .dl = ?0 I, and it is later extended to a more general form1,2,3,4 involving the socalled displacement current Id, ? B .dl=?0 (I+Id). Here the line integral is to be taken along a closed Amperian loop, and I is the net conventional current that penetrates any surface bounded by the loop. In its steady-current form (without Id), Ampere's law is used to find the magnetic field generated by highly symmetric arrangements of current-carrying wires, for example, an infinite straight line of current or an infinite solenoid, in analogy with Gauss's law.

Reich, Gary

2013-11-01

35

Method of measuring direct and alternating currents with galvanic decoupling  

SciTech Connect

A method is described for measuring direct and alternating microcurrents with galvanic decoupling. The method is based on the dependence of the current drawn by an operational amplifier circuit on the current measured. The measuring circuit is galvanically decoupled by a transformer which also supplies the power for the electronics. The error of measurement is less than 0.4% for direct current and 0.8% for alternating currents in the frequency band 20 Hz to 10 kHz.

Provotorov, I.V.; Simakov, S.R.; Che En Un

1995-09-01

36

Alternating current neutral potentials on underground gas piping systems  

Microsoft Academic Search

Consumers Power Co. presents field-test and laboratory results to characterize alternating currents encountered on underground gas-piping systems. The currents measured are those deemed sufficient to cause arcing or shocks. Alternating currents occur in proximity to low-voltage electrical distribution systems, seemingly as the result of load differences among the conductors. Experiments prove that underground gas piping usually carries a majority or

Lathrop

1978-01-01

37

Model of superconducting alternating current bolometers  

NASA Astrophysics Data System (ADS)

We present a model of the response of superconducting AC bolometers to signal and noise using parameters and matrix formalism that were previously adopted in modeling DC bolometers and microcalorimeters. The model was developed to investigate novel AC bolometer designs, which have properties not described by previous models. It is applicable to kinetic inductance devices, kinetic inductance thermometers, AC transition edge sensors, and other technologies based on AC read out and frequency mixing. The AC bolometer model includes the temperature and current dependence of both resistive and inductive bolometers and microcalorimeters. The bolometers may be thermal or athermal. The model compactly describes the complex relationships between electrical and thermal signals and it simplifies the associated calculations. This model is useful for characterizing bolometers, predicting the effects of various noise sources on performance and designing new detectors. Additionally, a measurement technique is developed for characterizing these devices.

Lindeman, M. A.; Khosropanah, P.; Hijmering, R. A.

2013-02-01

38

Alternating-current glow and pseudoglow discharges in atmospheric pressure  

Microsoft Academic Search

Stabilization and control of alternating-current glow and pseudoglow discharges have been studied in atmospheric pressure static air and methane flow gas by a pin-to-pin configuration. The electrode configuration and input power control the amplitude and duration of the discharge current and current pulses. Glow and pseudoglow discharges have been applied to the methane conversion.

Yun Yang

2003-01-01

39

An Alternating Current Probe for Measurement of Magnetic Fields  

Microsoft Academic Search

A method of measuring magnetic field strengths is described which utilizes the incremental permeability of a small Permalloy core. Alternating-current excitation is used which in turn permits amplification and hence a relatively high sensitivity and accuracy.

E. C. Gregg

1947-01-01

40

Magnetic Losses of Iron in High Frequency Alternating Current Fields  

Microsoft Academic Search

A number of investigators have studied the power loss due to eddy currents and hysteresis in iron when placed in high frequency alternating current fields, but the results obtained are in wide disagreement. Using a new method, the author has investigated the variation of this loss with the frequency for several areas of cross section. The total loss is considered

John R. Martin

1929-01-01

41

Dynamic effects on nonlinear alternating current responses in electrorheological fluids  

Microsoft Academic Search

By using a perturbation approach, we investigate dynamic effects on nonlinear alternating current ac responses in electrorheological ER fluids under an ac or direct current electric field. We show that the dynamic effect due to a shear flow, which exerts a torque on ER particles and thus leads to the rotation of the particles about their centers, plays a significant

W. J. Tian; J. P. Huang; K. Yu

2006-01-01

42

Nonlinear Alternating Current Responses in Electrorheological Fluids:. Dynamic Effects  

Microsoft Academic Search

By using a perturbation approach, we investigate dynamic effects on nonlinear alternating current (ac) responses in electrorheological (ER) fluids under an ac or a direct current electric field. We show that the dynamic effect due to a shear flow plays a significant role in the responses. Our results can be well interpreted in the dielectric dispersion spectral representation, and they

K. W. Yu; W. J. Tian; J. P. Huang

2007-01-01

43

Dynamic effects on nonlinear alternating current responses in electrorheological fluids  

Microsoft Academic Search

By using a perturbation approach, we investigate dynamic effects on nonlinear alternating current (ac) responses in electrorheological (ER) fluids under an ac or direct current electric field. We show that the dynamic effect due to a shear flow, which exerts a torque on ER particles and thus leads to the rotation of the particles about their centers, plays a significant

W. J. Tian; J. P. Huang; K. W. Yu

2006-01-01

44

Nonlinear alternating current susceptibilities of rotating microparticles in electrorheological fluids  

Microsoft Academic Search

A perturbation approach [1] has been employed to investigate the nonlinear alternating current (AC) responses of the rotating microparticles in electrorheological (ER) fluids under AC or direct current electric fields. The shear flow of ER fluids exerts a torque on the particles and leads to the rotational motion of the particles about their centers [2]. We show that the dynamic

Kin Wah Yu; J. P. Huang; W. J. Tian

2006-01-01

45

Cyclic Voltammetry Experiment.  

ERIC Educational Resources Information Center

Describes a three-part experiment designed to introduce cyclic voltammetry to graduate/undergraduate students. Part 1 demonstrates formal reduction potential, redox electron transfer, diffusion coefficient, and electrochemical reversibility. Part 2 investigates electrochemical behavior of acetaminophen. Part 3 examines such experimental variables…

Van Benschoten, James J.; And Others

1983-01-01

46

Alternate Test of RF Mixers by Current Signatures  

Microsoft Academic Search

This paper describes an alternate test methodology for radio-frequency mixers. The methodology is based on current signatures obtained by sampling the filtered supply current when the circuit-under-test is stimulated by a single tone sinusoidal. Sampling of supply current instead of voltage eliminates the parasitics and loading due to test circuitry on the signal path, hence provides a non-invasive built-in-self-test methodology.

S. S. Akbay; A. Chatterjee

47

Suppression of current fluctuations in carbon nanotube field-effect transistors by applying alternating current  

Microsoft Academic Search

A method of suppressing current fluctuations in carbon nanotube field-effect transistors (CNTFETs) is proposed. We compared the time dependences of the drain current for direct current (DC) measurement and alternating current (AC) measurement with a lock-in amplifier. Drain-current fluctuations were highly suppressed by the AC with lock-in method in the small gate voltage regime. On the other hand, the current

Yasuhide Ohno; Kenzo Maehashi; Koichi Inoue; Kazuhiko Matsumoto

2008-01-01

48

Mesenchymal stem cell osteodifferentiation in response to alternating electric current.  

PubMed

The present study addressed adult human mesenchymal stem cell (MSC) differentiation toward the osteoblastic lineage in response to alternating electric current, a biophysical stimulus. For this purpose, MSCs (chosen because of their proven capability for osteodifferentiation in the presence of select bone morphogenetic proteins) were dispersed and cultured within electric-conducting type I collagen hydrogels, in the absence of supplemented exogenous dexamethasone and/or growth factors, and were exposed to either 10 or 40 ?A alternating electric current for 6 h per day. Under these conditions, MSCs expressed both early- (such as Runx-2 and osterix) and late- (specifically, osteopontin and osteocalcin) osteogenic genes as a function of level, and duration of exposure to alternating electric current. Compared to results obtained after 7 days, gene expression of osteopontin and osteocalcin (late-osteogenic genes) increased at day 14. In contrast, expression of these osteogenic markers from MSCs cultured under similar conditions and time periods, but not exposed to alternating electric current, did not increase as a function of time. Most importantly, expression of genes pertinent to the either adipogenic (specifically, Fatty Acid Binding Protein-4) or chondrogenic (specifically, type II collagen) pathways was not detected when MSCs were exposed to the aforementioned alternating electric-current conditions tested in the present study. The present research study was the first to provide evidence that alternating electric current promoted the differentiation of adult human MSCs toward the osteogenic pathway. Such an approach has the yet untapped potential to provide critically needed differentiated cell supplies for cell-based assays and/or therapies for various biomedical applications. PMID:23083071

Creecy, Courtney M; O'Neill, Christine F; Arulanandam, Bernard P; Sylvia, Victor L; Navara, Christopher S; Bizios, Rena

2012-11-29

49

Square-Wave Voltammetry  

NASA Astrophysics Data System (ADS)

Square-wave voltammetry (SWV) is one of the four major voltammetric techniques provided by modern computer-controlled electroanalytical instruments, such as Autolab and ?Autolab (both EcoChemie, Utrecht), BAS 100 A (Bioanalytical Systems), and PAR Model 384 B (Princeton Applied Research) [1]. The other three important techniques are single scan and cyclic staircase, pulse, and differential pulse voltammetry (see Chap. II.2). All four are either directly applied or after a preconcentration to record the stripping process. The application of SWV boomed in the last decade, first because of the widespread use of the instruments mentioned above, second because of a well-developed theory, and finally, and most importantly, because of its high sensitivity to surface-confined electrode reactions. Adsorptive stripping SWV is the best electroanalytical method for the determination of electroactive organic molecules that are adsorbed on the electrode surface [2].

Lovri?, Milivoj

50

Electrically Mediated Neuronal Guidance with Applied Alternating Current Electric Fields  

Microsoft Academic Search

Applied electric fields (EFs) have previously been presented as a potential method of inducing functional recovery after neural\\u000a trauma. To date, most of this research has focused on the application of a direct current (DC) stimulus to produce the desired\\u000a EF and induce neuronal growth. We propose that high duty-cycle alternating current (AC) stimulation is capable of inducing\\u000a similar EFs

Matthew S. Graves; Travis Hassell; Brooke L. Beier; Gabriel O. Albors; Pedro P. Irazoqui

2011-01-01

51

Global breakdown in an alternating current plasma display panel  

Microsoft Academic Search

In the alternating current plasma display panel, a widespread discharge can take place accidentally in a large number of cells in the upper or lower panel ends. The undesirable discharge is referred to as global breakdown. This is a serious problem, with consequences not only for display quality, but also for product reliability. The mechanism of the global breakdown was

Y. Ikeda; K. Suzuki; H. Fukumoto; M. Shibata; M. Ishigaki; J. P. Verboncoeur; P. J. Christenson; C. K. Birdsall

2001-01-01

52

Discharge Physics of Alternating Current Plasma Display Panels (PDPs)  

Microsoft Academic Search

In this paper, we describe the experimental techniques and numerical modeling approaches to understand the alternating current plasma display panel (ac PDP) discharge physics. Conventional ac PDP uses microscale dielectric barrier discharge, and the spatio-temporal visualization of discharge not only helps to understand the discharge dynamics, but also validates the models adopted in the computer simulation study of PDP cell.

Ki-Woong Whang; Joong Kyun Kim

2005-01-01

53

Sizing of cracks using the alternating current field measurement technique  

Microsoft Academic Search

Recently a new technique for the detection and sizing of cracks and defects has been introduced in Australia. The alternating current field measurement (ACFM) technique is an electromagnetic inspection method that uses hand-held probes, and computerised control, data acquisition and computational models. ACFM is more efficient than conventional inspection methods (e.g. UT, MT, RT) due to a reduced need for

R LeTessier; R. W Coade; B Geneve

2002-01-01

54

59. View of high voltage (4160 volts alternating current) electric ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

59. View of high voltage (4160 volts alternating current) electric load center and motor control center at mezzanine level in transmitter building no. 102. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

55

Thermal analyses of alternating current light-emitting diodes  

NASA Astrophysics Data System (ADS)

During studies of alternating current InGaN/GaN light-emitting diodes with the focus on thermal characteristics, we have identified three shortcomings in comparison with the DC-LEDs counterpart. Via laboratory experiments using infrared thermal imagers and numerical simulations using the Galerkin finite element method, approaches of suppressing these shortcomings are first speculated, then confirmed, and finally proposed.

Zhang, Ji-Hong; Wu, Bi-Qing; Shih, Tien-Mo; Lu, Yi-Jun; Gao, Yu-Lin; Ru-Gin Chang, Richard; Chen, Zhong

2013-10-01

56

Nonlinear response of superconductors to alternating fields and currents  

SciTech Connect

This report discusses the following topics on superconductivity: nonlinearities in hard superconductors such as surface impedance of a type II superconductimg half space and harmonic generation and intermodulation due to alternating transport currents; and nonlinearities in superconducting weak links such as harmonic generation by a long Josephson Junction in a superconducting slab.

McDonald, J.

1997-10-08

57

46 CFR 111.30-25 - Alternating-current ship's service switchboards.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Alternating-current ship's service switchboards. 111.30-25...111.30-25 Alternating-current ship's service switchboards. (a) Except...this section, each alternating-current ship's service switchboard must have...

2012-10-01

58

Describing current and potential markets for alternative-fuel vehicles  

SciTech Connect

Motor vehicles are a major source of greenhouse gases, and the rising numbers of motor vehicles and miles driven could lead to more harmful emissions that may ultimately affect the world`s climate. One approach to curtailing such emissions is to use, instead of gasoline, alternative fuels: LPG, compressed natural gas, or alcohol fuels. In addition to the greenhouse gases, pollutants can be harmful to human health: ozone, CO. The Clean Air Act Amendments of 1990 authorized EPA to set National Ambient Air Quality Standards to control this. The Energy Policy Act of 1992 (EPACT) was the first new law to emphasize strengthened energy security and decreased reliance on foreign oil since the oil shortages of the 1970`s. EPACT emphasized increasing the number of alternative-fuel vehicles (AFV`s) by mandating their incremental increase of use by Federal, state, and alternative fuel provider fleets over the new few years. Its goals are far from being met; alternative fuels` share remains trivial, about 0.3%, despite gains. This report describes current and potential markets for AFV`s; it begins by assessing the total vehicle stock, and then it focuses on current use of AFV`s in alternative fuel provider fleets and the potential for use of AFV`s in US households.

NONE

1996-03-26

59

Alternating-Current Ohmic Heating in a Helical Stellarator  

Microsoft Academic Search

A toroidal plasma is generated successively by an alternating-current discharge in a helical or non-planar torus, and is confined quasi-stationarily by a longitudinal magnetic field with a high rotational transform angle. The particle confinement time obtained experimentally is estimated to be 3-10 ms, which is compared with theoretical values for this system, and is much larger than the time of

Yasuyuki Funato; Sumio Kitajima; Hiroshige Watanabe

1984-01-01

60

Electromagnetic stirring with alternating current during electroslag remelting  

Microsoft Academic Search

An alternating current (AC)-operated electromagnetic stirring (EMS) device, using line frequency, was designed and built to\\u000a operate on a laboratory electroslag remelting (ESR) furnace for 150-mm-diameter ingots. Laboratory-scale experiments were\\u000a conducted employing both 4340 alloy steel and INCONEL 718 alloy as electrode material. The initiation of stirring is accompanied\\u000a by a thin strip of segregated material and favors the formation

Alec Mitchell; Bernardo Hernandez-Morales

1990-01-01

61

Frequency dependence of alternating current electrospray ionization mass spectrometry.  

PubMed

The novel effects resulting from the entrainment of low mobility ions during alternating current (ac) electrospray ionization are examined through mass spectrometry and voltage/current measurements. Curious phenomena such as pH modulation at high frequencies (>150 kHz) of an applied ac electric field are revealed and explained using simple mechanistic arguments. Current measurements are utilized to supplement these observations, and a simplified one-dimensional transient diffusion model for charge transport is used to arrive at a scaling law that provides better insight into the ac electrospray ionization process. Moreover, because of the different pathway for ion formation in comparison to direct current (dc) electrospray, ac electrospray (at frequencies >250 kHz) is shown to reduce the effects of ionization suppression in a mixture of two molecules with different surface activities. PMID:21417427

Chetwani, Nishant; Cassou, Catherine A; Go, David B; Chang, Hsueh-Chia

2011-03-21

62

Training Course for Power Operating Personnel. Lesson No. 6: Alternating-Current Generator Excitation.  

ERIC Educational Resources Information Center

|Subjects covered in this text are controlling the hydroelectric generator, generator excitation, basic principles of direct current generation, direction of current flow, basic alternating current generator, alternating and direct current voltage outputs, converting alternating current to direct current, review of the basic generator and…

Department of the Interior, Denver, CO. Engineering and Research Center.

63

46 CFR 111.30-25 - Alternating-current ship's service switchboards.  

Code of Federal Regulations, 2010 CFR

...Switchboards § 111.30-25 Alternating-current ship's service switchboards...g) of this section, each alternating-current ship's service switchboard...double-pole field switch; (3) Discharge clips; and (4) A...

2010-10-01

64

46 CFR 111.30-25 - Alternating-current ship's service switchboards.  

Code of Federal Regulations, 2010 CFR

...Switchboards § 111.30-25 Alternating-current ship's service switchboards...g) of this section, each alternating-current ship's service switchboard...double-pole field switch; (3) Discharge clips; and (4) A...

2009-10-01

65

Wireless voltammetry recording in unanesthetised behaving rats.  

PubMed

In vivo voltammetry is a valuable technique for rapid measurement of dopamine in the brain of freely behaving rats. Using a conventional voltammetry system, however, behavioural freedom is restricted by cables connecting the head assembly to the measurement system. To overcome these difficulties, we developed a wireless voltammetry system utilizing radio waves. This system consisted of a potentiostat and transmitter system that was mounted on the back of the rat, and a receiver and analysis system. A single-step pulse (100-250 mV) was applied at 4 Hz after an activation pulse to a carbon fibre recording electrode (diameter: 7 microm). Measurement of dopamine (detection limit: 2.7 x 10(-7)M) was demonstrated in vitro. In vivo experiment was performed at least 1 week after the recording electrode was implanted in the rat striatum. Administration of 2-phenylethylamine to rats increased dopamine signal current, which was consistent with the result in the microdialysis measurement. During a resident-intruder test, dopamine signal current in a resident rat increased upon introduction of an intruder rat. These results show that the present wireless system is useful for a long-term measurement of dopamine in behaving rats. PMID:17983679

Kagohashi, Maki; Nakazato, Taizo; Yoshimi, Kenji; Moizumi, Shunjiro; Hattori, Nobutaka; Kitazawa, Shigeru

2007-10-03

66

Lidocaine transport through living rat skin using alternating current.  

PubMed

The purpose of the study was to determine whether lidocaine could be transported through living rat skin using alternating current and to determine whether lidocaine transport depends on voltage. The drug delivery cell was originally constructed for the application of an electric field. Hairless rats were anaesthetised using sevoflurane, and a tracheotomy was performed. The drug delivery cell, with lidocaine solution in the donor cell, was placed on the abdominal skin. Samples were collected from the subcutaneous tissue using a microdialysis probe inserted into the abdominal subcutaneous tissue, and the lidocaine concentrations in the samples were determined using high-performance liquid chromatography. The lidocaine concentration in the rat skin increased in time, and voltage-dependency was approximately linear. The lidocaine concentration after the application of 20 V for 21 min was about ten-fold higher than that observed after 21 min of passive diffusion. Lidocaine was successfully transported through living rat skin in a voltage- and time-dependent manner. This drug delivery cell may contribute to local anaesthesia and pain management of human skin. PMID:16411635

Haga, H; Shibaji, T; Umino, M

2005-09-01

67

Transdermal delivery of lidocaine in vitro by alternating current.  

PubMed

The purpose of this study was to investigate whether lidocaine could be transported through excised rat skin in vitro using alternating current (AC). In addition, the relationships between factors such as voltage and frequency, and transported lidocaine concentration were studied using the in vitro model. A pair of platinum plate electrodes was installed at opposite ends of two cylindrical glass cells in parallel to the full-thickness rat skin. The donor compartment was filled with 10 % lidocaine hydrochloride, and the receptor compartment with Ringer solution. A sinusoidal wave was applied between the electrodes at 5 kinds of constant voltages at 1 kHz and at 4 kinds of frequencies at 20 volts. Our experimental system was successfully used to quantify the concentration of transported lidocaine induced by AC application. The applied sinusoidal waves evoked the transport of lidocaine through the rat skin at every voltage and frequency protocol. Our results suggest that the applied electric voltage and frequency affect the movement of the lidocaine ions. We conclude that the transdermal delivery of lidocaine by AC iontophoresis has a possibility to use for local anesthesia and the pain management of the skin. PMID:12715922

Kinoshita, Tatsuki; Shibaji, Takao; Umino, Masahiro

2003-03-01

68

Precision electronic speed controller for an alternating-current  

DOEpatents

A high precision controller for an alternating-current multi-phase electrical motor that is subject to a large inertial load. The controller was developed for and is particularly suitable for controlling, in a neutron chopper system, a heavy spinning rotor that must be rotated in phase-locked synchronism with a reference pulse train that is representative of an ac power supply signal having a meandering line frequency. The controller includes a shaft revolution sensor which provides a feedback pulse train representative of the actual speed of the motor. An internal digital timing signal generator provides a reference signal which is compared with the feedback signal in a computing unit to provide a motor control signal. In the preferred embodiment, the motor control signal is a weighted linear sum of a speed error voltage, a phase error voltage, and a drift error voltage, each of which is computed anew with each revolution of the motor shaft. The stator windings of the motor are driven by two amplifiers which are provided with input signals having the proper quadrature relationship by an exciter unit consisting of a voltage controlled oscillator, a binary counter, a pair of readonly memories, and a pair of digital-to-analog converters.

Bolie, Victor W. (Albuquerque, NM)

1988-01-01

69

Is Transcranial Alternating Current Stimulation Effective in Modulating Brain Oscillations?  

PubMed Central

Transcranial alternating current stimulation (tACS) is a promising tool for modulating brain oscillations, as well as a possible therapeutic intervention. However, the lack of conclusive evidence on whether tACS is able to effectively affect cortical activity continues to limit its application. The present study aims to address this issue by exploiting the well-known inhibitory alpha rhythm in the posterior parietal cortex during visual perception and attention orientation. Four groups of healthy volunteers were tested with a Gabor patch detection and discrimination task. All participants were tested at the baseline and selective frequencies of tACS, including Sham, 6 Hz, 10 Hz, and 25 Hz. Stimulation at 6 Hz and 10 Hz over the occipito-parietal area impaired performance in the detection task compared to the baseline. The lack of a retinotopically organised effect and marginal frequency-specificity modulation in the detection task force us to be cautious about the effectiveness of tACS in modulating brain oscillations. Therefore, the present study does not provide significant evidence for tACS reliably inducing direct modulations of brain oscillations that can influence performance in a visual task.

Brignani, Debora; Ruzzoli, Manuela; Mauri, Piercarlo; Miniussi, Carlo

2013-01-01

70

Separation of individual neurons using dielectrophoretic alternative current fields.  

PubMed

Experimental investigations into the dynamics of neuronal networks are a fundamental step towards understanding how the nervous system works. Memory formation and development are associated with changes in the electrical activity of the neurons. To understand the changes in the electrical activity, it is essential to conduct in vitro studies on individual neurons. Hence, there is an enormous need to develop novel ways for isolating and localizing individual neurons. To this end, we designed and fabricated a 4x4 multiple microelectrode array system to spatially arrange neurons by generating dielectrophoretic traps using gradient alternating current (AC) fields. We characterized the electric field distribution inside our test platform by using three-dimensional finite element modeling (FEM) and estimated the location of neurons over the electrode array. As the first stage in forming a neuronal network, dielectrophoretic AC fields were employed to separate the neurons from the glial cells and to position individual neurons over single electrodes. The extracellular electrical activity from a single neuron was recorded. The frequency spectrum of the electrical activity was generated using fast Fourier transformation analysis (FFT) to determine the characteristic burst rates of individual neurons. PMID:15020092

Prasad, Shalini; Zhang, Xuan; Yang, Mo; Ni, Yingchun; Parpura, Vladimir; Ozkan, Cengiz S; Ozkan, Mihrimah

2004-05-30

71

Ion transfer voltammetry by a simple two polarized interfaces setup.  

PubMed

Cyclic voltammetry and square wave voltammetry have been used to investigate the transfer of highly hydrophilic ions, including anions and cations, by a simple two polarized interfaces setup. The expression of apparent half-wave potential has been established detailedly by virtue of theory of sampled-current voltammetry involving semi-infinite linear diffusion, which indicates that the property of coupled ion transfer reaction has an effect on the position of the voltammogram on the potential scale. Since the data obtained agree well with literature values, it seems convincing to determine the transfer energies of those highly hydrophilic ions which are very important and have not been reported yet. Then it has been demonstrated as a novel way in combination with sensitive and fast square wave voltammetry for determining the transfer Gibbs energy of complex ions such as miscellaneous inorganic ions. PMID:20795693

Zhou, Min; Gan, Shiyu; Zhong, Lijie; Su, Bin; Niu, Li

2010-09-15

72

CURRENT STATUS OF METHYL BROMIDE ALTERNATIVES RESEARCH IN FLORIDA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Since 1993, extensive research on alternatives to methyl bromide has been conducted in Florida at USDA, ARS and the University of Florida in cooperation with growers and industry. Although alternative fumigants have proven efficacious for certain pests, no single registered chemical is effective as...

73

Current Alternative Energy Research and Development in Illinois, June 1985.  

National Technical Information Service (NTIS)

The Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of no...

R. Swager

1985-01-01

74

Current Alternative Energy Research and Development in Illinois, December 1988.  

National Technical Information Service (NTIS)

The Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of no...

R. Swager

1989-01-01

75

Current Alternative Energy Research and Development in Illinois, June 1984.  

National Technical Information Service (NTIS)

This Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of n...

R. Swager

1984-01-01

76

Current Alternative Energy Research and Development in Illinois.  

National Technical Information Service (NTIS)

The Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of no...

R. Swager

1987-01-01

77

Fiber optic DC magnetic field sensor with alternating current phase tracing  

Microsoft Academic Search

A sensitive DC magnetic field sensor based on magnetostrictive straining of optical fibers was demonstrated, which utilizes alternating current phase tracing (PTAC) homodyne scheme to eliminate phase drift. Comparison was carried out experimentally between direct current phase tracing (PTDC) and alternating current phase tracing, then expressions were presented. The results showed that the PTAC had better performance both in stabilization

Jianguang Xin; Mengchun Pan; Dixiang Chen; Qi Zhang; JiaFei Hu

2009-01-01

78

The measurement of regular and irregular surface cracks using the alternating current potential difference technique  

Microsoft Academic Search

The alternating current (AC) potential difference technique for measuring the growth of regular and irregular surface cracks is described. This technique is based on injecting high frequency alternating current into the metal specimen and measuring the change in voltage on the surface produced by the presence of a crack. The high frequency current tends to flow in a thin layer

1995-01-01

79

Current distribution and ac loss for a superconducting rectangular strip with in-phase alternating current and applied field  

Microsoft Academic Search

The case of ac transport at in-phase alternating applied magnetic fields for a superconducting rectangular strip with finite thickness is investigated. The applied magnetic field is considered to be perpendicular to the current flow. We present numerical calculations assuming the critical-state model of the current distribution and ac loss for various values of aspect ratio, transport current and applied field

E. Pardo; F. Gömöry; J. Souc; J. M. Ceballos

2007-01-01

80

Pressure filtration of alumina suspensions under alternating current field  

Microsoft Academic Search

The relation of applied pressure-height of piston during pressure filtration was measured for aqueous 7vol.% suspensions of positively charged 150nm alumina particles at 0.2mm\\/min of crosshead speed of piston. The dispersed suspension changed to a flocculated suspension at a critical applied pressure (phase transition pressure, ?Ptc), and the flocculated suspension was consolidated at a low pressure (??Ptc). Application of alternating

Koichiro Matsushima; Yoshihiro Hirata; Naoki Matsunaga; Soichiro Sameshima

2010-01-01

81

Wireless Architectural Alternatives: Current Economic Valuations versus Broadband Options  

Microsoft Academic Search

Abstract There has been an assumption,that spectrum,can be divided into segments,and then auctioned,off. It has been assumed,that this is optimal in terms of its benefit to the public and that the FCC in so doing is optimizing the public good. There has been an alternative conjecture, termed the “Gilder” conjecture, that segmenting bandwidth,is not the best means,and that using all

Terrence P. Mcgarty; Muriel Medard

82

Alternatives to animal testing: current status and future perspectives  

Microsoft Academic Search

On the occasion of the 20th anniversary of the Center for Alternative Methods to Animal Experiments (ZEBET), an international\\u000a symposium was held at the German Federal Institute for Risk Assessment (BfR) in Berlin. At the same time, this symposium was\\u000a meant to celebrate the 50th anniversary of the publication of the book “The Principles of Humane Experimental Technique” by\\u000a Russell

Manfred Liebsch; Barbara Grune; Andrea Seiler; Daniel Butzke; Michael Oelgeschläger; Ralph Pirow; Sarah Adler; Christian Riebeling; Andreas Luch

2011-01-01

83

Current alternative energy research and development in Illinois, June 1984  

SciTech Connect

This Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in May, 1984 or that had been completed after November 1983. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1984-06-01

84

Current alternative energy research and development in Illinois, December 1985  

SciTech Connect

This Directory is intended to acquaint researchers, policy makers, and citizens with recent activities in alternative energy research, development, and demonstration projects. The topics covered are limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in November 1985 or that had been completed after May 1985. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1985-12-01

85

Current alternative energy research and development in Illinois, June 1985  

SciTech Connect

The Directory is intended to acquaint researchers, policy makers, and citizens with recent activities in alternative energy research, development, and demonstration projects. The topics covered are limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in May, 1985 or that had been completed after November, 1984. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1985-06-01

86

Current alternative energy research and development in Illinois  

SciTech Connect

This Directory is intended to acquaint researchers, policy makers, and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in November, 1984 or that had been completed after May, 1984. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1984-12-01

87

Current alternative energy research and development in Illinois. Annual report  

SciTech Connect

This directory is intended to acquaint researchers, policy makers, and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in October 1987 or that had been completed after December 1986. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1987-12-01

88

Current alternative energy research and development in Illinois  

SciTech Connect

This Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in May, 1983 or that had been completed after September, 1982. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1983-06-01

89

Current alternative energy research and development in Illinois  

SciTech Connect

This Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered have been limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in Sept. 1983 or that had been completed after May 1983. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1983-12-01

90

Current Practices in Almond Pasteurization and Alternative Approaches  

Technology Transfer Automated Retrieval System (TEKTRAN)

Almonds are among the important export products of the United States and Turkey. As of September 1, 2007, the mandatory law for 4-log pasteurization of raw almonds became effective in the United States. Currently, in general, raw almonds are pasteurized by using propylene oxide, where 4-log pasteu...

91

Noncancer Risk Assessment: A Probabilistic Alternative to Current Practice  

Microsoft Academic Search

Based on imperfect data and theory, agencies such as the United States Environmental Protection Agency (USEPA) currently derive “reference doses” (RfDs) to guide risk managers charged with ensuring that human exposures to chemicals are below population thresholds. The RfD for a chemical is typically reported as a single number, even though it is widely acknowledged that there are significant uncertainties

Sandra J. S. Baird; Joshua T. Cohen; John D. Graham; Alexander I. Shlyakhter; John S. Evans

1996-01-01

92

Teaching Electrical Energy, Voltage and Current: An Alternative Approach.  

ERIC Educational Resources Information Center

A program for teaching the concepts of electric energy, voltage, and current is proposed. The ideas and concepts are introduced in a sequence that places more emphasis on some aspects that are normally treated very briefly. A phenomenological orientation, qualitative and quantitative micro- and macroscopic treatments, and the inclusion of the…

Licht, Pieter

1991-01-01

93

Analysis for discharge-radiation dynamics in alternating current plasma display panels  

Microsoft Academic Search

An analytical method to study the discharge-radiation dynamics (DRD) in alternating current plasma display panels was developed. The input parameters for this DRD analysis were experimentally determined panel voltage and current wave forms. Discharge voltage, current, and power wave forms in the discharge volume of a cell were first obtained from the measured panel voltage and current wave forms using

Keizo Suzuki; Kenichi Yamamoto; Hiroshi Kajiyama; Shirun Ho; Norihiro Uemura; Katsunori Muraoka

2004-01-01

94

Paired Pulse Voltammetry for differentiating complex analytes  

PubMed Central

Although fast-scan cyclic voltammetry (FSCV) has contributed to important advances in neuroscience research, the technique is encumbered by significant analytical challenges. Confounding factors such as pH change and transient effects at the microelectrode surface make it difficult to discern the analytes represented by complex voltammograms. Here we introduce paired-pulse voltammetry (PPV), that mitigates the confounding factors and simplifies the analytical task. PPV consists of a selected binary waveform with a specific time gap between each of its two comprising pulses, such that each binary wave is repeated, while holding the electrode at a negative potential between the waves. This allows two simultaneous yet very different voltammograms (primary and secondary) to be obtained, each corresponding to the two pulses in the binary waveform. PPV was evaluated in the flow cell to characterize three different analytes, (dopamine, adenosine, and pH changes). The peak oxidation current decreased by approximately 50%, 80%, and 4% for dopamine, adenosine, and pH, in the secondary voltammogram compared with primary voltammogram, respectively. Thus, the influence of pH changes could be virtually eliminated using the difference between the primary and secondary voltammograms in the PPV technique, which discriminates analytes on the basis of their adsorption characteristics to the carbon fiber electrode. These results demonstrate that PPV can be effectively used for differentiating complex analytes.

Jang, Dong Pyo; Kim, Inyong; Chang, Su-Youne; Min, Hoon Ki; Arora, Kanika; Marsh, Michale P.; Hwang, Sun-Chul; Kimble, Christopher J.; Bennet, Kevin E.

2012-01-01

95

Stripping Voltammetry of Pb and Cu using a Microcantilever Electrode  

SciTech Connect

Microfabricated silicon microcantilevers coated with gold on one side have been used as working electrode in a three-electrode electrochemical arrangement. In addition to electrochemical current, cantilever bending has been used as a signal for monitoring electrode reactions on the cantilever surface. The microcantilever bending was measured by an optical beam deflection method as the surface potential was scanned and electrochemical reactions occurred on the surface. The microcantilever bending due to differential surface stress was used to sense Pb and Cu using cyclic voltammetry (CV) and linear sweep stripping voltammetry (LSSV).

Bange, Adam [ORNL; Brown, Gilbert M [ORNL; Senesac, Larry R [ORNL; Thundat, Thomas George [ORNL

2009-01-01

96

Determination of Ti(IV) at low levels by voltammetry  

Microsoft Academic Search

Accurate and rapid determination of Ti(IV) at low or trace levels in HClO4, HClO4–NaClO3, H2SO4, H2C2O4, H2C2O4–NaClO3 and H3PO4 media can be done by voltammetry at the mercury drop electrode. New reliable procedures implementing square wave and differential pulse voltammetries are described. Kinetic peak currents resulting from slow complex formation are proportional to the analytical concentration of Ti(IV). Calibration lines,

Denise Krulic; Nicolas Fatouros; Nathalie Larabi; Eric Mahé

2007-01-01

97

Direct-current and alternating-current electroluminescence of MOS capacitors with Si-implanted SiO 2  

Microsoft Academic Search

The direct-current and alternating-current electroluminescence (d.c.- and a.c.-EL) characteristics of n+-polysilicon MOS capacitors with 50nm Si-implanted SiO2 have been measured to discuss EL stability and frequency response. While the d.c.-EL intensity increases with time t at small constant current density (JG) and decreases for large JG, it decreases with t monotonously under constant gate voltage (VG) condition. The time dependence

Toshihiro Matsuda; Yasuhiro Honda; Takashi Ohzone

1998-01-01

98

Electrical characteristics of ultra-thin gate oxides (<3 nm) prepared by direct current superimposed with alternating-current anodization  

Microsoft Academic Search

Ultra-thin gate oxides with thickness smaller than 3 nm were prepared by anodic oxidation (anodization) in deionized water under direct-current biasing superimposed with alternating-current signal (DAC-ANO). It is experimentally observed that the DAC-ANO oxides after suitable high temperature annealing have better electrical characteristics than conventional rapid thermal oxides (RTO). Other advantages of DAC-ANO oxides include lower leakage current, higher time-zero

Zhi-Hao Chen; Szu-Wei Huang; Jenn-Gwo Hwu

2004-01-01

99

Inappropriate implantable cardioverter-defibrillator shock due to external alternating current leak: report of two cases.  

PubMed

Two cases are reported of inappropriate implantable cardioverter-defibrillator shocks due to external alternating current leak. Electromagnetic interference (EMI) can mimic cardiac signals and cause inappropriate implantable cardioverter-defibrillator (ICD) shocks. EMI can arise from the normal functioning of electrical appliances or from alternating current leak. The two cases had inappropriate ICD shocks due to alternating current leak from a power drill in one and a washing machine in the other. The need for detailed advice on handling electrical equipment is emphasized. PMID:15763537

Chan, Ngai Yin; Wai-Ling Ho, Lillian

2005-03-01

100

XV. An alternating current method for collector analysis of discharge-tubes  

Microsoft Academic Search

An alternating current method is described which enables the second derivative of the current-voltage curve of an auxilliary electrode in a gaseous discharge to be obtained directly, provided the discharge conditions are sufficiently stable. This obviates the necessity for double graphical differentation of the ordinary electron current-voltage curve when the second derivative id required for substitution in Druyvesteyn's distribution equation

R. H. Sloane; E. I. R. MacGregor

1934-01-01

101

Precautions Against Stray Magnetic Fields in Measurements with Large Alternating Currents  

Microsoft Academic Search

In electric power stations, it is often necessary to make accurate measurements of current or power when the instruments are located near to the cables carrying large alternating currents. The magnetic field produced by these currents may constitute a serious source of error in the measurements unless careful precautions are taken to guard against such disturbing effects. This paper summarizes

Francis B. Silsbee

1929-01-01

102

Asymmetric Marcus-Hush theory for voltammetry.  

PubMed

The current state-of-the-art in modeling the rate of electron transfer between an electroactive species and an electrode is reviewed. Experimental studies show that neither the ubiquitous Butler-Volmer model nor the more modern symmetric Marcus-Hush model are able to satisfactorily reproduce the experimental voltammetry for both solution-phase and surface-bound redox couples. These experimental deviations indicate the need for revision of the simplifying approximations used in the above models. Within this context, models encompassing asymmetry are considered which include different vibrational and solvation force constants for the electroactive species. The assumption of non-adiabatic electron transfer is also examined. These refinements have provided more satisfactory models of the electron transfer process and they enable us to gain more information about the microscopic characteristics of the system by means of simple electrochemical measurements. PMID:23508098

Laborda, Eduardo; Henstridge, Martin C; Batchelor-McAuley, Christopher; Compton, Richard G

2013-06-21

103

Engineering aspects of the ISTTOK operation in a multicycle alternating flat-top plasma current regime  

Microsoft Academic Search

The main engineering aspects of the tokamak ISTTOK operation in a multicycle alternating flat-top plasma current regime are presented. AC discharges have been obtained feeding the ohmic and vertical magnetic field circuits with a specially designed alternating power supply, based on a single electrolytic capacitor bank and a fast insulated gate bipolar transistor (IGBT) H-bridge, feedback controlled by a discreet

H Fernandes; C. A. F Varandas; J. A. C Cabral; H Figueiredo; R Galvão

1998-01-01

104

The role of the alternating current component in a discharge with oscillating electrons  

Microsoft Academic Search

Measurements of the distribution of potential in a discharge and of the electron oscillation spectra are used to determine the anomalous diffusion coefficient of the discharge plasma associated with the development of diocotron instability. The discharge current component conditioned by constant fields and collisions is determined along with the mean value of the current component conditioned by an alternating field.

G. V. Smirnitskaia

1976-01-01

105

Alternating current loss characteristics in (bismuth,lead)SCCO and yttrium barium copper oxide superconducting tapes  

Microsoft Academic Search

Alternating current (AC) loss and current carrying capacity are two of the most crucial considerations in large-scale power applications of high temperature superconducting (HTS) conductors. AC losses result in an increased thermal load for cooling machines, and thus increased operating costs. Furthermore, AC losses can stimulate quenching phenomena or at least decrease the stability margin for superconducting devices. Thus, understanding

Doan Ngoc Nguyen

2007-01-01

106

An observable consequence of molecular rotational inertia in an alternating current Kerr effect  

Microsoft Academic Search

A study of phase angles of the electric birefringence including inertia is proposed in the case of the simultaneous action of two electric fields, namely a direct current (dc) bias field added to an alternating current (ac) field of angular frequency ?. The solution of the Fokker–Planck–Kramers (FPK) equation applied to the orientational motion of a polar (permanent moment ?)

Jean-Louis Déjardin; Georges Debiais

1991-01-01

107

Calorimetric apparatus for alternating current loss measurements on high-temperature superconductors  

Microsoft Academic Search

The use of high-temperature superconductors in electric power components requires the knowledge of their alternating current (ac) losses. Methods are therefore needed to characterize the conductors with respect to their ac losses under applicationlike conditions. In this article we describe a calorimetric setup for ac loss measurements on long length high-temperature superconductors carrying ac transport currents in ac external magnetic

N. Magnusson; S. Hörnfeldt

1998-01-01

108

A constant-current shock source for providing direct or alternating current output  

Microsoft Academic Search

A vacuum-tube constant-current shock source. providing ac, smooth dc, and pulsating dc output is described. In addition to\\u000a output flexibility. the shock source is compact, inexpensive to construct. and has undergone 4 years of testing and laboratory\\u000a use. Operating instructions, theory of operation, and suggested modifications are included along with performance specifications.

Robert A. Stewart; Sam L. Campbell

1970-01-01

109

A threshold analysis of cricket cercal interneurons by an alternating air-current stimulus  

Microsoft Academic Search

1.The wind-velocity threshold of cercal interneurons of the cricketGryllus bimaculatus D. was measured using a sinusoidally alternating aircurrent stimulus. Two stimulus parameters, peak velocity and alternating frequency of the air current, were separately controlled. The measurements of the minimum velocity evoking a response at a variety of frequencies gave a threshold curve. The stimulating apparatus was a wind tunnel which

Masamichi Kanou; Tateo Shimozawa

1984-01-01

110

Direct current and alternating current electrical transport properties of regioregular poly[3-(4-alkoxyphenyl)-thiophenes  

Microsoft Academic Search

In this paper, the direct current and alternating current (ac) electrical transport properties of doped and undoped regioregular poly[3-(4-alkoxyphenyl)-thiophenes], where the alkoxy groups are O-(CH2)n-1CH3 with n=1,4,6, and 8, have been investigated. The films have been synthesized by an experimental procedure based on the oxidation of 3-(4-alkoxylphenyl)-thiophenes with molecular oxygen in presence of VO(acac)2, as the catalyst. Unlike other examples

M. Barra; M. Biasiucci; A. Cassinese; P. D'Angelo; A. C. Barone; A. Carella; A. Roviello

2007-01-01

111

Anodic stripping voltammetry enhancement by redox magnetohydrodynamics.  

PubMed

The effect of an external magnetic field on linear scan anodic stripping voltammetry (ASV) in solutions of 10(-6)-10(-7) M concentrations of lead, cadmium, and copper at mercury films on glassy carbon electrodes has been investigated. A high concentration of Hg(2+) was added to the analyte solution to induce a large cathodic current during the deposition step. Therefore, a large Lorentz force from the net flux of charge through the magnetic field resulted in convection due to magnetohydrodynamics. The faster delivery of analytes to the mercury film electrode during deposition caused an increase in the anodic stripping peaks. The effect of varying Hg(2+) concentrations (0-60 mM) and magnetic field strengths (0-1.77 T) on the enhancement of the stripping peaks was investigated. Enhancements as large as 129% for peak currents and 167% for peak areas were observed. An enhancement of approximately 100% was observed when 60 mM Fe(3+) replaced high concentrations of Hg(2+). This method of convection exhibits promise for small-volume ASV analysis with possible improved limits of detection and decreased preconcentration times. PMID:15080758

Clark, Emily A; Fritsch, Ingrid

2004-04-15

112

Direct-current-like Phase Space Manipulation Using Chirped Alternating Current Fields  

SciTech Connect

Waves in plasmas can accelerate particles that are resonant with the wave. A dc electric field also accelerates particles, but without a resonance discrimination, which makes the acceleration mechanism profoundly different. Whereas wave-particle acceleration mechanisms have been widely discussed in the literature, this work discusses the direct analogy between wave acceleration and dc field acceleration in a particular parameter regime explored in previous works. Apart from the academic interest of this correspondence, there may be practical advantages in using waves to mimic dc electric fields, for example, in driving plasma current with high efficiency.

P.F. Schmit and N.J. Fisch

2010-02-01

113

Electrical anaesthesia the use of a combination of alternating and direct electrical current in dogs  

Microsoft Academic Search

Summary  Observations on the use of an apparatus producing an alternating square wave superimposed on a direct electric current are\\u000a made Thiopentone 15 mg \\/kg was administered intravenously to dogs and the animals were mtubated When definite muscular, respiratory,\\u000a and cardiovascular response to painful stimuli had returned, electric current was applied through palladium electrodes on\\u000a the vertex and the roof of

J. W. R. McIntyre; P. James Voloshin

1964-01-01

114

Spike frequency of the nodal membrane generated by high-frequency alternating current  

Microsoft Academic Search

Changes in membrane potential of single frog motor nerve fibres due to alternating current (ac) between 4 kHz and 20 kHz were recorded in the air gap equipment under constant current conditions at 20°C. The experimental findings were compared with the results of computations on the basis of potential clamp data. Ac shifted mean membrane potential (averaged for every ac

Burkhart Bromm

1975-01-01

115

Two-dimensional particle simulation of a sustained discharge in an alternating current plasma display panel  

Microsoft Academic Search

A plasma discharge due to a sustaining pulse of an alternating current plasma display panel was analyzed using a two-dimensional particle-in-cell code, and basic characteristics of the plasma discharge were calculated. The characteristics of the plasma discharge due to a sustaining pulse are as follows. (i) A large amount of space charge remained after drawing the discharge current. This excess

Y. Ikeda; K. Suzuki; H. Fukumoto; J. P. Verboncoeur; P. J. Christenson; C. K. Birdsall; M. Shibata; M. Ishigaki

2000-01-01

116

Simple analytical expression for electron temperature in an alternating current plasma display discharge  

Microsoft Academic Search

A simple analytical expression was derived for electron temperature Te in discharge conditions typical for an alternating current plasma display panel discharge, in which the least possible number of parameters was introduced so as to provide good physical insight into the mechanisms of determining Te under various discharge conditions. From this derivation, an explicit dependence of Te on discharge parameters

K. Muraoka; K. Suzuki; M. Azumi; Y. Yamagata; M. Yagi

2007-01-01

117

Theoretical Study of sputtered Material Redeposition on the Target in Alternating Current Gas Discharge Plasma  

Microsoft Academic Search

Sputtering of solid surfaces by plasma ions in the alternating current (AC) gas discharge takes place in many devices such as gas-discharge displays, plasma etching systems, arc discharge lamps etc. At relatively high background gas pressures the sputtered atoms collide with gas atoms in the vicinity of the surface and then move in the diffusion mode. As a result, some

Guennadi Bondarenko; Olga Bonk; Vladimir Kristya

2000-01-01

118

Calculation of time-dependent flows of sputtered material in the asymmetric alternating current glow discharge  

Microsoft Academic Search

Diffusion transport of material sputtered from the surface of the powered electrode in the asymmetric alternating current discharge is theoretically studied. It is shown that amplitudes of the non-stationary component of the sputtered atom (SA) flow densities at the electrodes depend on the discharge frequency and two dimensionless parameters, which are functions of the SA mass, its mean free path

G. G. Bondarenko; O. G. Bonk; V. I. Kristya

2007-01-01

119

Influence of crack length on crack depth measurement by an alternating current potential drop technique  

Microsoft Academic Search

An alternating current potential drop (ACPD) technique is used for sizing depth of surface cracks in metallic components. Crack depth estimations are prone to large deviations when ACPD measurements are made on very shallow and finite length cracks, especially in low conducting materials such as austenitic stainless steel (SS). Detailed studies have been carried out to investigate the influence of

Manoj K. Raja; S. Mahadevan; B. P. C. Rao; S. P. Behera; T. Jayakumar; Baldev Raj

2010-01-01

120

Electron temperature and plasma density in surface-discharged alternating-current plasma display panels  

Microsoft Academic Search

The electron temperature and plasma density at the lateral distance of 125 ?m from the center of sustaining electrode gap have been investigated by a Langmuir probe along with the high-speed discharge image in coplanar alternating current plasma display panels. The plasma density at the lateral distance of 125 ?m from the center of sustaining electrode gap is shown to

Eun Ha Choi; Jeong Chull Ahn; Min Wook Moon; Jin Goo Kim; Myung Chul Choi; Choon Gon Ryu; Sung Hyuk Choi; Tae Seung Cho; Yoon Jung; Guang Sup Cho; Han Sup Uhm

2002-01-01

121

The addressing characteristics of an alternating current plasma display panel adopting a ramping reset pulse  

Microsoft Academic Search

The characteristics of the address discharge of an alternating current plasma display panel (ac PDP) adopting a ramping reset pulse were studied using two-dimensional (2-D) numerical simulation. We investigated the principal parameters of the reset pulse for a successful address discharge. In this paper, we suggest a new parameter, the terminal voltage of the ramping reset pulse, and its effects

Joong Kyun Kim; Jin Ho Yang; Woo Joon Chung; Ki Woong Whang

2001-01-01

122

Stability of alternating current discharges between water drops on insulation surfaces  

Microsoft Academic Search

Discharges between water drops are important in the ageing of hydrophobic outdoor insulators. They may also be important in the processes leading up to flashover of these insulators in high pollution conditions. This paper considers discharges between drops when a limited alternating current is available, as experienced by an ageing insulator in service. A phenomenon is identified in which the

S M Rowland; F C Lin

2006-01-01

123

Initial decomposition mechanisms and products of dimethyl methylphosphonate in an alternating current discharge  

Microsoft Academic Search

The efficiency of decomposition of dimethyl methylphosphonate (DMMP) vapor from a helium stream in an atmospheric pressure alternating current capacitive discharge has been determined to range from 50 to 100% depending upon the input concentration and flow rate and is improved with trace oxygen addition. In the absence of oxygen the principal discharge products are methane, ethane, formaldehyde, and carbon

Mark E. Fraser; Harold G. Eaton; Ronald S. Sheinson

1985-01-01

124

Diagnostics of the microdischarge in an alternating current plasma display panel (AC PDP)  

Microsoft Academic Search

In this paper, we describe the experimental approaches to understand the microdischarge physics of an alternating current plasma display panel (ac PDP) cell. We discuss the experimental techniques to explore the major parameters to understand the operation of ac PDP such as the vacuum ultra violet (VUV) emission and wall charge variation. Regarding the discharge dynamics, the detailed VUV emission

Ki-Woong Whang; Joong Kyun Kim

2006-01-01

125

Critical Voltage for the Formation of Ozone by the Alternating-Current Discharge  

Microsoft Academic Search

This seclion will accept reports of new work, prwided these are terse and contain few figures, and especially few halftone cuts. The Editorial Board will not hold itself responsible for opinions expressed by the corre>pondents. Contributions to this seclion must reach the olfice of the Managing Editor Critical Voltage for the Formation of Ozone by the Alternating-Current Discharge ]0 a

M. Senkus; A. C. Grubb

1935-01-01

126

Operation of the tokamak ISTOKK in a multicycle alternating flat-top plasma current regime  

Microsoft Academic Search

Operation of the tokamak ISTTOK in a multicycle alternating square wave plasma current regime is reported. Discharges with seven half-cycles without dwell times, over a total time span of about five times the maximum duration of a single DC discharge, were obtained by feeding the primary of the transformer with an electrolytic capacitor bank switched in polarity by a fast

J. A. C. Cabral; H. Fernandes; H. Figueiredo; C. A. F. Varandas

1997-01-01

127

A B-spline approach to alternating current field measurement for railroad inspection  

Microsoft Academic Search

Reliable detection and evaluation of surface breaking defects in rails caused by rolling contact fatigue mechanisms is of paramount importance for the rail industry. Experimental work has showed that alternating current field measurement (ACFM) techniques are suitable for the high-speed inspection of rails. This paper presents an algorithm based on B-spline estimation that analyses the shape of the ACFM signal

M. Papaelias; F. P. G. Marquez; J. M. C. Munoz; C. Roberts

2008-01-01

128

Structural optimization of 2-D array probe for alternating current field measurement  

Microsoft Academic Search

A double U-shaped orthogonal inducer for the alternating current field measurement (ACFM) is presented, which could extend the limitation of the direction of tested cracks and decrease the loss of magnetic flux compared to the single rectangular inducer. The structure of the testing probe was optimized to meet the expectations of the pointwise magnetic field measurement and to decrease every

Chen Guo-ming; Li Wei; Wang Ze-xin

2007-01-01

129

Defect Visualization for Alternating Current Field Measurement Based on the Double U-Shape Inducer Array  

Microsoft Academic Search

To meet the engineering expectations of defect visualization for alternating current field measurement (ACFM) technique, a double U-shape orthogonal inducer array is introduced. This excitation method allow to generate a rotational electromagnetic field, which makes it possible to defect detection independent of the defect orientation and provides sufficient signal data for defect visualization. The inversion methods of surface shape and

CHEN Guoming

130

Uniform ac field in anisotropic bar and alternating current potential difference stress measurement  

Microsoft Academic Search

Some theoretical and experimental studies are presented on magnetostrictive anisotropy (stress induced anisotropy) in a long circular steel bar. An explicit analytical solution to the problem of uniform axial alternating current (ac) distribution in a cylindrical bar which retains magnetic and electrical anisotropy was established. By relating the stress level to the amount of magnetic anisotropy in the material, an

Jianwei Zhou; Kaisheng Chen; William D. Dover

1999-01-01

131

Theory of four-point alternating current potential drop measurements on conductive plates  

Microsoft Academic Search

Measurements of alternating current potential drop (ACPD) made at the surface of a conductive plate can be used to determine, non-destructively, the parameters of the plate such as its thickness, electrical conductivity and linear effective magnetic permeability. In order to invert the measured potential drop to yield values for these parameters, a theoretical model is needed. In this work, closed

John R. Bowler; Nicola Bowler

2007-01-01

132

Experimental Demonstration of the Equivalence of a Mechanically Oscillated Electrostatic Charge to an Alternating Current  

Microsoft Academic Search

Method of testing equivalence of a mechanically osciallted charge to an alternating current.-The apparatus consisted of a cylinder approximately 4 inches in diameter by 9 inches long, constructed of insulating material, but coated on the out-side with a thin sheet of copper foil which could be charged to potentials which varied from 1400 to 2600 volts. The cylinder was arranged

Richard C. Tolman; Daniel B. McRae

1929-01-01

133

High Voltage Direct Current (HVDC) technology: An alternative means of power transmission  

Microsoft Academic Search

Energy consumption in the world is increasing, as well as the demand for efficient and quality electric power supply that ensures a greener environment. Consequently, the deployment of renewable energy sources has become imperative. The use of renewable resources like hydropower, solar and wind cannot be possible without electric transmission lines. High Voltage Alternating Current (HVAC), though an established technology

Chijioke Joe-Uzuegbu; Gloria Chukwudebe

2011-01-01

134

Assessment of flow and cure monitoring using direct current and alternating current sensing in vacuum-assisted resin transfer molding  

NASA Astrophysics Data System (ADS)

Vacuum-assisted resin transfer molding (VARTM) is an emerging manufacturing technique that holds promise as an affordable alternative to traditional autoclave molding and automated fiber placement for producing large-scale structural parts. In VARTM, the fibrous preform is laid on a single-sided tool, which is then bagged along with the infusion and vacuum lines. The resin is then infused through the preform, which causes simultaneous wetting in its in-plane and transverse directions. An effective sensing technique is essential so that comprehensive information pertaining to the wetting of the preform, arrival of resin at various locations, cure gradients associated with thickness and presence of dry spots may be monitored. In the current work, direct current (dc) and alternating current sensing/monitoring techniques were adopted for developing a systematic understanding of the resin position and cure on plain weave S2-glass preforms with Dow Derakane vinyl ester VE 411-350, Shell EPON RSL 2704/2705 and Si-AN epoxy as the matrix systems. A SMARTweave dc sensing system was utilized to conduct parametric studies: (a) to compare the flow and cure of resin through the stitched and non-stitched preforms; (b) to investigate the influence of sensor positioning, i.e. top, middle and bottom layers; and (c) to investigate the influence of positioning of the process accessories, i.e. resin infusion point and vacuum point on the composite panel. The SMARTweave system was found to be sensitive to all the parametric variations introduced in the study. Furthermore, the results obtained from the SMARTweave system were compared to the cure monitoring studies conducted by using embedded interdigitated (IDEX) dielectric sensors. The results indicate that SMARTweave sensing was a viable alternative to obtaining resin position and cure, and was more superior in terms of obtaining global information, in contrast to the localized dielectric sensing approach.

Vaidya, Uday K.; Jadhav, Nitesh C.; Hosur, Mahesh V.; Gillespie, John W., Jr.; Fink, Bruce K.

2000-12-01

135

Uniform ac field in anisotropic bar and alternating current potential difference stress measurement  

NASA Astrophysics Data System (ADS)

Some theoretical and experimental studies are presented on magnetostrictive anisotropy (stress induced anisotropy) in a long circular steel bar. An explicit analytical solution to the problem of uniform axial alternating current (ac) distribution in a cylindrical bar which retains magnetic and electrical anisotropy was established. By relating the stress level to the amount of magnetic anisotropy in the material, an electromagnetic stress model was then developed for cylindrical bars under uniaxial stress using the analytical solution. For the application of this model, experimental stress measurements on mild steel bars with different radii were conducted based on the alternating current potential difference (ACPD) technique. During the test, a form of alternating current field measurement (ACFM) instrumentation, known as the ACFM crack microgauge, was used to inject a uniform ac current into the steel bars and to measure the electrical field on the bar surface. The ACPD stress measurement results showed that the theoretical stress model could predict the stress values with the calibration of a magnetic anisotropic parameter.

Zhou, Jianwei; Chen, Kaisheng; Dover, William D.

1999-07-01

136

Use of Biosensors as Alternatives to Current Regulatory Methods for Marine Biotoxins  

PubMed Central

Marine toxins are currently monitored by means of a bioassay that requires the use of many mice, which poses a technical and ethical problem in many countries. With the exception of domoic acid, there is a legal requirement for the presence of other toxins (yessotoxin, saxitoxin and analogs, okadaic acid and analogs, pectenotoxins and azaspiracids) in seafood to be controlled by bioassay, but other toxins, such as palytoxin, cyclic imines, ciguatera and tetrodotoxin are potentially present in European food and there are no legal requirements or technical approaches available to identify their presence. The need for alternative methods to the bioassay is clearly important, and biosensors have become in recent years a feasible alternative to animal sacrifice. This review will discuss the advantages and disadvantages of using biosensors as alternatives to animal assays for marine toxins, with particular focus on surface plasmon resonance (SPR) technology.

Vilarino, Natalia; Fonfria, Eva S.; Louzao, M. Carmen; Botana, Luis M.

2009-01-01

137

Field dependent alternating current susceptibility of metalorganically deposited YBa2Cu3O7-delta films  

Microsoft Academic Search

The field amplitude and frequency dependent complex alternating current susceptibility chi(Hm, f) of YBa2Cu3O7-delta films metalorganically deposited on different substrates with different processes has been measured at 77 K and studied in relation with their microstructures and some modeling results. It is shown that chi(Hm) for films with well aligned grains and a high Jc is of Bean type with

D.-X. Chen; E. Pardo; A. Sanchez; M. N. Iliev; S.-S. Wang; Z.-H. Han

2007-01-01

138

Plasma propagation speed and electron temperature in surface-discharge alternating-current plasma display panels  

Microsoft Academic Search

The electron temperature and plasma density in coplanar alternating-current plasma display panels (AC-PDPs) have been experimentally investigated by a micro Langmuir probe and the high speed discharge images in this experiment. It is noted in this experiment that the electron temperature obtained from both the micro Langmuir probe and high speed ICCD camera decreases from 1.8 eV to 0.8 eV

J. C. Ahn; M. W. Moon; M. C. Choi; C. G. Ryu; Y. Jung; G. S. Cho; E. H. ChoiE; H. S. Uhm

2001-01-01

139

Plasma propagation speed and electron temperature in surface-discharged alternating-current plasma display panels  

Microsoft Academic Search

Summary form only given, as follows. The space and time-resolved discharge images from an alternating-current plasma display panels (ac-PDPs) has been observed by a high-speed single frame camera, and visualized as motion images. The time duration of the main discharge glow is. also shown to be about 200 ns and a faint light is continuously emitted even after 350 ns

J. C. Ahn; M. W. Moon; M. C. Choi; S. H. Choi; K. B. Song; K. S. Cho; E. H. Choi

2001-01-01

140

Characteristics of vacuum ultraviolet emission from a surface discharge type alternating current plasma display panel cell  

Microsoft Academic Search

We have measured the time variation of 147 nm vacuum ultraviolet (VUV) resonance emission as well as the continuum such as 152 and 173 nm VUV and the two-dimensional images of 147 nm VUV from the He-Xe discharge in a surface discharge type single alternating current (ac) plasma display panel (PDP) cell using an image intensified charge-coupled device camera. A

Heui Seob Jeong; Jeong Hyun Seo; Cha Keun Yoon; Joong Kyun Kim; Ki-Woong Whang

1999-01-01

141

Discharge Characteristics and Technology Development of Alternating-Current Plasma Display Panels  

Microsoft Academic Search

Comparison of luminosity-modulation switching principles in matrix displays showed that an AC-PDP (alternating-current plasma display panel) can produce 30 to 50-inch diagonal displays of superior motionpicture quality and of a low price. Comparison with a process plasma and a thermonuclear fusion plasma showed that an AC-PDP plasma in each cell has extremely low degrees of ionization, uniformity, and steadiness. The

Keizo Suzuki

2003-01-01

142

The effect of Fe-doped magnesium oxide thin film in alternative current plasma display panel  

Microsoft Academic Search

In order to improve the discharge characteristics of MgO thin film as a protective layer in an alternative current plasma display panel, Fe-doped MgO thin films was introduced. Both the surface characteristics of the deposited thin films and the electro-optical properties of 4 inch test panels were investigated. It has been demonstrated experimentally that ac PDP with Fe-doped MgO protective layer

Jung-Woo Ok; Don-Kyu Lee; Dong-Hyun Kim; Hae June Lee; Ho-Jun Lee; Chung-Hoo Park

2009-01-01

143

Plasma Propagation Speed and Electron Temperature in Surface-Discharged Alternating-Current Plasma Display Panels  

Microsoft Academic Search

Space and time resolved discharge images from an alternating-current plasma display panel have been observed by a high-speed single-frame camera to investigate the electron temperatures. The plasma propagation speed on the cathode was measured to be 0.9 mm\\/mus and 1.3 mm\\/mus, respectively, and that on the anode was measured to be 1.8 mm\\/mus and 2.7 mm\\/mus, respectively, at driving frequencies

Jeong-Chull Ahn; Soon-Bae Kim; Tae-Seung Cho; Myung-Chul Choi; Dai-Geun Joh; Min-Wug Moon; Yoon-Ho Seo; Seung-Oun Kang; Guang-Sup Cho; Eun-Ha Choi; Han-Sup Uhm

2002-01-01

144

Characteristics of vacuum ultraviolet emission from a surface discharge type alternating current plasma display panel cell  

Microsoft Academic Search

We have measured the time variation of 147 nm vacuum ultraviolet (VUV) resonance emission as well as the continuum such as 152 and 173 nm VUV and the two-dimensional images of 147 nm VUV from the He–Xe discharge in a surface discharge type single alternating current (ac) plasma display panel (PDP) cell using an image intensified charge-coupled device camera. A

Heui Seob Jeong; Jeong Hyun Seo; Cha Keun Yoon; Joong Kyun Kim; Ki-Woong Whang

1999-01-01

145

High-voltage plasma generators of alternating current with rod electrodes stationary operating on oxidizing media  

Microsoft Academic Search

The stationary plasma generators of alternating current with rod electrodes and power from 5 kW up to 50 kW have been developed in IEE RAS.The generators are used in plasmachemical installations intended for various practical applications including waste destruction and processing with synthesis-gas production.These are single-phase and three-phase high-voltage lasma generators, which prime property is ability to work on oxidizing

Ph. G. Rutberg; I. I. Kumkova; V. E. Kuznetsov; S. D. Popov; A. Ph. Rutberg; A. A. Safronov; V. N. Shiryaev; A. V. Surov

2007-01-01

146

High-Voltage Plasma Generators of Alternating Current with Rod Electrodes Stationary Operating on Oxidizing Media  

Microsoft Academic Search

Summary form only given. The stationary plasma generators of alternating current with rod electrodes and power from 5 kW up to 50 kW have been developed in IEE RAS. The generators are used in plasmachemical installations intended for various practical applications including waste destruction and processing with synthesis-gas production. These are single-phase and three-phase high-voltage plasma generators, which prime property

P. G. Rutberg; I. I. Kumkova; V. E. Kuznetsov; S. D. Popov; A. P. Rutberg; A. A. Safronov; V. N. Shiryaev; A. V. Surov

2007-01-01

147

Low frequency and low magnetic field effects on the alternating current volume susceptibility of cuprate superconductors  

Microsoft Academic Search

The real and imaginary parts of the alternating current volume susceptibility are simultaneously measured on a cylindrical sample of ceramic superconducting YBa2Cu3O7?? in the frequency range from 0.5 to 1×103 Hz. A relatively small frequency dependence of the shielding diamagnetism is observed below 2 Hz and above 250 Hz. A logarithmic dependence of the peak loss temperature is observed which

Farid Bensebaa; Janusz Hankiewicz; Larry Kevan

1993-01-01

148

Alternating current potential-drop measurement of the depth of case hardening in steel rods  

Microsoft Academic Search

The case depth of induction-hardened steel rods has been determined using multi-frequency alternating current potential-drop measurements. Experimental results are analyzed using a model which approximates the variation in the material properties of a hardened rod by assuming that a homogeneous core is surrounded by a homogeneous case-hardened layer of uniform thickness. Experimental measurements on an untreated rod are used to

John R. Bowler; Yongqiang Huang; Haiyan Sun; Jonathan Brown; Nicola Bowler

2008-01-01

149

Alternating-current transport losses of melt-cast processed Bi2212 bulk superconductor bars  

Microsoft Academic Search

Using a melt-casting method, we have fabricated two pieces of Bi-2212 bulk superconductor bar with square and rectangular cross-sections, and we have investigated the alternating-current (ac) transport self-field losses at 77 K. Despite the main contribution of hysteresis loss of the superconductor, there is some difference in the loss behaviour between these two samples. To elucidate the origin, we make

T. Tsukamoto; R. Inada; N. Inagaki; H. Andoh; T. Sugiura; A. Oota

2003-01-01

150

Fabrication of nanoelectrodes based on controlled placement of carbon nanotubes using alternating-current electric field  

Microsoft Academic Search

A fabrication process for nanoelectrodes with a nanogap of ;35 nm is presented. This process is based on controlled placement of carbon nanotubes on metal electrodes using an alternating-current ~ac! electric field. One bundle of single-walled nanotubes~SWNT! was placed successfully between two electrodes using an ac electric field. Electrical measurement of the SWNT bundle through the two metal contacts shows

Zhi Chen; Wenchong Hu; Jun Guo; Kozo Saito

2004-01-01

151

Initial dielectric aging in a lead magnesium niobate ceramic under strong alternating current fields  

Microsoft Academic Search

The weak field dielectric aging behaviours of lead magnesium niobate (Pb[Mg1\\/3Nb2\\/3]O3) ceramics have been extensively investigated. In this paper, however, we focused on the dielectric aging of a Mg and Mn doped PMN ceramic under various alternating current (ac) fields. It is found that the strong ac fields generally suppress the aging rate, particularly at low measurement frequencies.

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

1998-01-01

152

Finite Element Analysis of Alternating Write-Current-Induced Pole Tip Protrusion in Magnetic Recording Heads  

Microsoft Academic Search

This paper presents a finite element analysis of alternating write-current-induced pole tip protrusion (WPTP) generated in longitudinal magnetic recording (LMR) heads. An integrated magneto-thermal-mechanical model is developed for the simulations of the electromagnetic Joule heating generated in the LMR writer, the slider temperature distribution, and the slider deformation during writing. The computed results are compared with the experimental measurements in

Suping Song; Lisha Wang; Victor Rudman; Dori Fang; Kroum Stoev; James Wang; Bill Sun

2007-01-01

153

Vacuum Poloidal Magnetic Field of Tokamak in Alternating-Current Operation  

NASA Astrophysics Data System (ADS)

Vacuum poloidal magnetic field of tokamak in alternating-current (AC) operation is investigated. It is found that the vacuum magnetic field in AC operation is qualitatively different from that in direct-current (DC) operation. In the DC case, the vacuum magnetic field varies along the poloidal direction with one period, while in the AC case, the vacuum magnetic field varies along the poloidal direction with two periods. This implies that two sets of vertical field coil may be needed for the AC operation.

Guo, Wei; Wang, Shaojie; Li, Jiangang

2010-12-01

154

Methods, systems and apparatus for controlling operation of two alternating current (AC) machines  

SciTech Connect

A system is provided for controlling two alternating current (AC) machines via a five-phase PWM inverter module. The system comprises a first control loop, a second control loop, and a current command adjustment module. The current command adjustment module operates in conjunction with the first control loop and the second control loop to continuously adjust current command signals that control the first AC machine and the second AC machine such that they share the input voltage available to them without compromising the target mechanical output power of either machine. This way, even when the phase voltage available to either one of the machines decreases, that machine outputs its target mechanical output power.

Gallegos-Lopez, Gabriel (Torrance, CA); Nagashima, James M. (Cerritos, CA); Perisic, Milun (Torrance, CA); Hiti, Silva (Redondo Beach, CA)

2012-06-05

155

Spike frequency of the nodal membrane generated by high-frequency alternating current.  

PubMed

Changes in membrane potential of single frog motor nerve fibres due to alternating current (ac) between 4 kHz and 20 kHz were recorded in the air gap equipment under constant current conditions at 20 degrees C. The experimental findings were compared with the results of computations on the basis of potential clamp data. Ac shifted mean membrane potential (averaged for every ac period) in the direction of depolarization. The mean depolarization Vm depended on current strength I; it disappeared when the sodium permeability was blocked, in the experiments by tetrodotoxin. In a current range between about 1 and 3 fold threshold strength the ac initiated repetitive activity with response frequencies v between averaged 120 Hz and 820 Hz or in the computations even higher; v depended logarithimically on current strength, but was independent of ac frequency. Elimination of current amplitude I from the nonlinear realtions v(I) and Vm(I) led to a linear function between v and Vm. Both v and Vm depended markedly on prepolarization of the node. The results were attributed to the preferred activation of the sodium permeability under maintained high frequency ac stimulation. Differences between computations and constant current experiments occurred for very long stimulus duration when rhythmical discharges died out in the experiment. PMID:1079083

Bromm, B

1975-01-01

156

Carbon nanofiber electrode array for electrochemical detection of dopamine using fast scan cyclic voltammetry  

PubMed Central

A carbon nanofiber (CNF) electrode array was integrated with the Wireless Instantaneous Neurotransmitter Sensor System (WINCS) for detection of dopamine using fast scan cyclic voltammetry (FSCV). Dopamine detection performance by CNF arrays was comparable to that of traditional carbon fiber microelectrodes (CFMs), demonstrating that CNF arrays can be utilized as an alternative carbon electrodes for neurochemical monitoring.

Koehne, Jessica E.; Marsh, Michael; Boakye, Adwoa; Douglas, Brandon; Kim, In Yong; Chang, Su-Youne; Jang, Dong-Pyo; Bennet, Kevin E.; Kimble, Christopher; Andrews, Russell; Meyyappan, M.; Lee, Kendall H.

2012-01-01

157

Modeling of magnetic properties and alternate current losses in high-Tc superconductors using a power law voltage-current characteristic  

Microsoft Academic Search

This article presents numerical diffusion models which describe the electromagnetic properties and alternate current (ac) losses of a high-Tc superconducting tape carrying transport current. The models simulate the tape as a highly nonlinear conductor with equivalent resistivity being a function of J, the local current density, as deduced from a power law E-J characteristic of the material. The power law

A. E. Mahdi; A. Tami; R. L. Stoll

1999-01-01

158

Modeling of magnetic properties and alternate current losses in high-Tc superconductors using a power law voltage–current characteristic  

Microsoft Academic Search

This article presents numerical diffusion models which describe the electromagnetic properties and alternate current (ac) losses of a high-Tc superconducting tape carrying transport current. The models simulate the tape as a highly nonlinear conductor with equivalent resistivity being a function of J, the local current density, as deduced from a power law E–J characteristic of the material. The power law

A. E. Mahdi; A. Tami; R. L. Stoll

1999-01-01

159

A Preliminary Study of Cyclic Voltammetry of a Conducting Polymer  

NASA Astrophysics Data System (ADS)

An electroactivity study of active species in a conducting polymer uses the Cyclic Voltammetry (CV) analytical technique. A technique is chosen in which the potential of an electrode is the controlled variable, while the current is the observed variable. Two plates of platinum were used as a counting electrode and a working electrode, respectively. A reference electrode used Ag/AgCl. Polypyrrole (PPy), polythiophene (PT) and poly (3-acetic acid thiophene) (PT3AA) were conducting polymer material synthesized using iron (III) chloride as a catalyst. The effect of a supporting electrolyte of sodium perchlorate anhydrous NaClO4.H2O on conducting polymers is also studied.

Hasiah, S.; Ibrahim, K.; Senin, H. B.; Mohamed, Faizatul Shima

2007-05-01

160

Laboratory animal science in China: current status and potential for adoption of Three R alternatives.  

PubMed

This paper aims to describe the development of laboratory animal science in China on the basis of historical evidence and recent national survey data, and to identify the problems facing the adoption of Three R alternatives. The authors undertook a national survey in 2006, by means of a questionnaire sent to 31 provinces, municipalities and autonomous regions, and also compared data from a variety of sources, including several national surveys and published papers. Laboratory animal science in China has developed rapidly over the past 30 years, as a result of a combination of economic, governmental and societal forces. More than 100,000 people work in the field of laboratory animal science, in 2,000 laboratory animal centres, institutes, universities, organisations, and companies. During the year of our survey, more than 19 million laboratory animals were produced from 320 licensed production facilities. Approximately 16 million laboratory animals were used in animal experiments, in 1530 facilities licensed for their use. The scale of the market for the supply and use of laboratory animals is huge, and thus it is very important to improve the level of adoption of these alternatives, in education, research and testing. For China, this presents a significant economic and technological opportunity in the field of biosciences research. The concept of the Three Rs first appeared in China in the 1980s, when the scale of laboratory animal sciences was starting to increase. In the 1990s, the Three Rs concept became commonly accepted among laboratory animal scientists, and began to appear in government documents. In the first decade of the 21st century, the Three Rs principles have become increasingly applied in our day-to-day work. But further time is still needed to achieve the full application of the Three Rs principles, especially the adoption of Three R alternatives. This paper describes the achievements in China relating to laboratory animal science, the use of Three R alternatives, and animal welfare, and shows that there is currently great potential for the adoption of alternatives. The information will help scientists and organisations around the world to gain better insight into the current state of laboratory animal science in China, and hopefully, will enable them to give advice on how we can improve the adoption of Three R alternatives in our country. PMID:20377304

Kong, Qi; Qin, Chuan

2010-03-01

161

An alternating pulse current technique for potentiometric stripping analysis (APC-PSA).  

PubMed

The response signal in PSA measurements - the transition time tau - can be considerably amplified by using a special pulse technique which we call "alternating pulse current (APC)". The sensitivity of the method is thereby considerably increased. This is achieved by modulating the current with a high frequency in a square wave mode during the stripping phase in such a way, that cathodic and anodic pulses alternate, so that the species to be determined is stripped and - at least partially - redeposited during the procedure. The transition time tau is not affected by the absolute values of the currents and of the times they flow. The amplification is determined by their respective ratios only. The equations holding are derived and proven experimentally by measurements on very dilute Pb solutions. The APC-PSA technique has also been applied for systems termed 'irreversible' such as U and Tc, where also a considerable amplification could be achieved. The probable reasons are discussed and future developments and investigations are depicted. PMID:15045242

Beck, H P; Schiestel, T

1996-08-01

162

Dielectrophoretic particle dynamics in alternating-current electro-osmotic micropumps  

NASA Astrophysics Data System (ADS)

This letter deals with the dynamics of dielectric microparticles in alternating-current electro-osmotic micropumps, which is based on the competitive interplay of inertial, dielectrophoretic, and viscous drag forces. The electric field and the electro-osmotic flow are modeled and computed by means of finite elements and particle trajectories are evaluated taking into account the forces above. Thereby, mean traveling height and velocity depend on driving voltage and frequency, which allows for an effective type of particle manipulation and separation. The obtained particle velocities show good agreement with measured velocities of hollow glass beads in a device realized in SU8/glass technology.

Weiss, Bernhard; Hilber, Wolfgang; Holly, Roman; Gittler, Philipp; Jakoby, Bernhard; Hingerl, Kurt

2008-05-01

163

Thermomigration in flip-chip SnPb solder joints under alternating current stressing  

NASA Astrophysics Data System (ADS)

Thermomigration in flip-chip solder joints is investigated using alternating currents and infrared microscopy to decouple it from electromigration effect. It is found that the thermal gradient in solder bump can be as high as 2143 °C/cm when 9.2×104 A/cm2 was applied at 100 °C. Markers fabricated by focus ion beam are employed to measure the thermomigration rate. The thermomigration flux is measured to be 3.3×1013 at./cm2. With the known thermal gradient, the molar heat of 26.8 kJ/mole has been obtained for the transport of Pb.

Hsiao, Hsiang-Yao; Chen, Chih

2007-04-01

164

Electrochemical oxidation of the carbide wastes of hard alloys using alternating current  

NASA Astrophysics Data System (ADS)

The electrochemical oxidation of the carbide wastes of a W-Co alloy has been studied by gas, electron-probe microanalysis, and X-ray diffraction analyses. The experiments are carried out using halfwave sinusoidal alternating current. It is established that a CO2 + CO mixture forms under such conditions in a gaseous phase in volumetric ratio of 2: 1 and that a tungsten deposit forms in an anode sludge mainly in the form of hydrated tungsten oxide WO2(OH)2. Marketable products are obtained in the form of pure CO3O4 and WO3.

Bryukvin, V. A.; Palant, A. A.; Levchuk, O. M.; Tsybin, O. I.

2012-03-01

165

Ab initio study of the alternating current impedance of a molecular junction.  

PubMed

The small-bias conductance of the C6 molecule, stretched between two metallic leads, is studied using time-dependent density functional theory within the adiabatic local density approximation. The leads are modeled by jellium slabs, the electronic density and the current density are described on a grid, whereas the core electrons and the highly oscillating valence orbitals are approximated using standard norm-conserving pseudopotentials. The jellium leads are supplemented by a complex absorbing potential that serves to absorb charge reaching the edge of the electrodes and hence mimic irreversible flow into the macroscopic metal. The system is rapidly exposed to a ramp potential directed along the C6 axis, which gives rise to the onset of charge and current oscillations. As time progresses, a fast redistribution of the molecular charge is observed, which translates into a direct current response. Accompanying the dc signal, alternating current fluctuations of charge and currents within the molecule and the metallic leads are observed. These form the complex impedance of the molecule and are especially strong at the plasmon frequency of the leads and the lowest excitation peak of C6. We study the molecular conductance in two limits: the strong coupling limit, where the edge atoms of the chain are submerged in the jellium and the weak coupling case, where the carbon atoms and the leads do not overlap spatially. PMID:15268494

Baer, Roi; Seideman, Tamar; Ilani, Shahal; Neuhauser, Daniel

2004-02-15

166

Computational analysis shows why transcranial alternating current stimulation induces retinal phosphenes  

NASA Astrophysics Data System (ADS)

Objective. Transcranial alternating current stimulation (tACS), which is a novel technique for the manipulation of cortical oscillations, can generate subjective visual sensations (phosphenes). In this work, we computationally investigate the current that reaches the eyes from tACS electrodes in order to show that phosphenes induced by tACS are retinal in origin. Approach. The finite-element method is used for modelling the path of the current in an anatomically realistic model of the head for various electrode montages. The computational results are used for analysing previous experimental data to investigate the sensitivity of the eye to electrical stimulation. Main results. Depending on the locations of both the stimulating and reference electrodes, a small portion of the stimulation current chooses a path that goes through the eyes. Due to the sensitivity of the retina to electrical stimulation, even distant electrodes can produce a sufficiently strong current at the eyes for inducing retinal phosphenes. Significance. The interference from retinal phosphenes needs to be considered in the design of tACS experiments. The occurrence of phosphenes can be reduced by optimizing the locations of the electrodes, or potentially increasing the number of reference electrodes to two or more. Computational modelling is an effective tool for guiding the electrode positioning.

Laakso, Ilkka; Hirata, Akimasa

2013-08-01

167

Transcranial alternating current stimulation reduces symptoms in intractable idiopathic cervical dystonia: a case study.  

PubMed

Idiopathic cervical dystonia (ICD) is a movement disorder often resulting in profound disability and pain. Treatment options include oral medications or other invasive procedures, whereas intractable ICD has been shown to respond to invasive (deep) brain stimulation. In the present blinded, placebo-controlled case study, transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) has been applied to a 54-year old patient with intractable ICD. Results showed that 15 Hz tACS had both immediate and cumulative effects in dystonic symptom reduction, with a 54% reduction in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score, and a 75% in the TWSTRS Pain Scale. These effects were persistent at 30-days follow-up. This is the first report to demonstrate a significant and lasting therapeutic effect of non-invasive electrical brain stimulation in dystonia. PMID:23149130

Angelakis, E; Liouta, E; Andreadis, N; Leonardos, A; Ktonas, P; Stavrinou, L C; Miranda, P C; Mekonnen, A; Sakas, D E

2012-11-10

168

Air pollution control residues from waste incineration: Current UK situation and assessment of alternative technologies  

SciTech Connect

Current disposal options for APC residues in the UK and alternative treatment technologies developed world-wide have been reviewed. APC residues are currently landfilled in the UK where they undergo in situ solidification, although the future acceptability of this option is uncertain because the EU waste acceptance criteria (WAC) introduce strict limits on leaching that are difficult to achieve. Other APC residue treatment processes have been developed which are reported to reduce leaching to below relevant regulatory limits. The Ferrox process, the VKI process, the WES-PHix process, stabilisation/solidification using cementitious binders and a range of thermal treatment processes are reviewed. Thermal treatment technologies convert APC residues combined with other wastes into inert glass or glass-ceramics that encapsulate heavy metals. The waste management industry will inevitably use the cheapest available option for treating APC residues and strict interpretation and enforcement of waste legislation is required if new, potentially more sustainable technologies are to become commercially viable.

Amutha Rani, D. [Department of Civil and Environmental Engineering, Imperial College, London SW7 2AZ (United Kingdom); Department of Materials, Imperial College, London SW7 2AZ (United Kingdom); Boccaccini, A.R. [Department of Materials, Imperial College, London SW7 2AZ (United Kingdom); Deegan, D. [Tetronics Ltd., South Marston Business Park, Swindon, Wiltshire SN3 4DE (United Kingdom); Cheeseman, C.R. [Department of Civil and Environmental Engineering, Imperial College, London SW7 2AZ (United Kingdom)], E-mail: c.cheeseman@imperial.ac.uk

2008-11-15

169

Current Perspectives on the Use of Alternative Species in Human Health and Ecological Hazard Assessments  

PubMed Central

Background: Traditional animal toxicity tests can be time and resource intensive, thereby limiting the number of chemicals that can be comprehensively tested for potential hazards to humans and/or to the environment. Objective: We compared several types of data to demonstrate how alternative models can be used to inform both human and ecological risk assessment. Methods: We reviewed and compared data derived from high throughput in vitro assays to fish reproductive tests for seven chemicals. We investigated whether human-focused assays can be predictive of chemical hazards in the environment. We examined how conserved pathways enable the use of nonmammalian models, such as fathead minnow, zebrafish, and Xenopus laevis, to understand modes of action and to screen for chemical risks to humans. Results: We examined how dose-dependent responses of zebrafish embryos exposed to flusilazole can be extrapolated, using pathway point of departure data and reverse toxicokinetics, to obtain human oral dose hazard values that are similar to published mammalian chronic toxicity values for the chemical. We also examined how development/safety data for human health can be used to help assess potential risks of pharmaceuticals to nontarget species in the environment. Discussion: Using several examples, we demonstrate that pathway-based analysis of chemical effects provides new opportunities to use alternative models (nonmammalian species, in vitro tests) to support decision making while reducing animal use and associated costs. Conclusions: These analyses and examples demonstrate how alternative models can be used to reduce cost and animal use while being protective of both human and ecological health. Citation: Perkins EJ, Ankley GT, Crofton KM, Garcia-Reyero N, LaLone CA, Johnson MS, Tietge JE, Villeneuve DL. 2013. Current perspectives on the use of alternative species in human health and ecological hazard assessments. Environ Health Perspect 121:1002–1010;?http://dx.doi.org/10.1289/ehp.1306638

Ankley, Gerald T.; Crofton, Kevin M.; Garcia-Reyero, Natalia; LaLone, Carlie A.; Johnson, Mark S.; Tietge, Joseph E.; Villeneuve, Daniel L.

2013-01-01

170

Hemispheric differences in word-meaning processing: Alternative interpretations of current evidence  

PubMed Central

Background Drawing heavily on results from studies with divided visual field (dvf) presentation, current models of hemispheric differences in word semantic processing converge on a proposal (henceforth, “the standard model”) that is increasingly being applied in studies of individuals with brain damage. According to this model, left hemisphere processes focus word meanings to their core, whereas right hemisphere processes keep wider representations active. Aims This paper has three aims: (a) to raise concerns about methodological aspects of the dvf studies that are usually cited in support for the standard model, specifically assumptions about interpretation of lateral dvf prime presentation and priming measures; (b) to highlight areas of further research and theoretical clarification, with reference to studies with central presentation and general models of word-meaning processing; and (c) to discuss the implications of these concerns for deriving a model of hemispheric differences in word-meaning processing, using evidence from paired word priming studies as an example. Main Contribution The paper discusses problematic assumptions about paired word priming studies of hemispheric contributions to word semantic processing and proposes further research to clarify these assumptions. Furthermore, it introduces an alternative interpretation of the available data, which provides a more parsimonious account of hemispheric engagement in the paired word semantic priming task. Conclusions Current evidence about hemispheric differences in word-meaning processing is far from conclusive. It is important to consider alternative interpretations of the available evidence when applying models based on this evidence to the study of language disorders. The alternative account proposed in this paper suggests that LH processing, rather than generally reducing activated word meanings to their core, is important for maintaining meanings that are unambiguous and consistent.

Fassbinder, Wiltrud; Tompkins, Connie A.

2009-01-01

171

Voltammetry at the Thin-Film Mercury Electrode (TFME).  

ERIC Educational Resources Information Center

|Reviewed is the use of the Thin-Film Mercury Electrode for anodic stripping voltammetry, simple voltammetry of solution cations and cathodic stripping voltammetry for the determination of an environmentally important molecule, thiourea. The construction of a simple potentiostat and applications for student laboratory courses are included. (CW)|

Pomeroy, R. S.; And Others

1989-01-01

172

Measurement of the Hall coefficient and electrical conductivity in semi-conductors by the method of an alternating magnetic field and alternating current  

Microsoft Academic Search

A description is given of electronic equipment which enables the simultaneous measurement of the Hall coefficient and the electrical conductivity by using an alternating magnetic field and alternating current. The instrument is adapted for measuring a minimum Hall coefficient of 3.10-11 Vcm\\/AGand electrical resistance 10-5 Oto 103 O;the smallest measurable Hall voltage is 1 µ V.Deviations from the results, obtained

Jan Dusek

1959-01-01

173

Experimental aspects of solid-state voltammetry  

SciTech Connect

This paper describes the properties of poly(ether) polymer electrolytes as solvent media for solid-state voltammetry. Experimental requirements for microelectrode voltammetry and results for the dependency of diffusive transport of electroactive solutes on polymer solvent molecular weight, structure, and temperature (and related phase state) are described for eight poly(ether)s: linear poly(ethylene oxides) MW = 400, 1000, 2000, and 600 000 (Me{sub 2}PEG-400, Me{sub 2}PEG-1000, Me{sub 2}PEG-2000, PEO-600 000), linear poly(propylene oxide) MW = 4000 (PPO-4000), the comb polymer poly(bis[(methoxyethoxy)ethoxy]phosphazine) (MEEP), the block copolymer poly(ether)-poly(urethane urea)(PEUU), and the cross-linked poly(ether) network PEO. 28 refs., 10 figs., 1 tab.

Wooster, T.T.; Longmire, M.L.; Zhang, H. [Univ. of North Carolina, Chapel Hill, NC (United States)] [and others

1992-05-15

174

Analysis for discharge-radiation dynamics in alternating current plasma display panels  

SciTech Connect

An analytical method to study the discharge-radiation dynamics (DRD) in alternating current plasma display panels was developed. The input parameters for this DRD analysis were experimentally determined panel voltage and current wave forms. Discharge voltage, current, and power wave forms in the discharge volume of a cell were first obtained from the measured panel voltage and current wave forms using known geometrical configurations and electric circuit calculations. Intrinsic discharge parameters, such as electron temperature and density, were then determined to satisfy these discharge wave forms under the assumption of a hydrodynamic approach. A one-dimensional discharge structure with two regions (cathode fall and positive column) and several other assumptions which are plausible from the discharge physics point of view were also adopted. These assumptions took account of known cross sections and energies of electron-impact excitation and ionization of discharge gas atoms, and a secondary electron emission coefficient of the dielectric surface at the cathode side induced by ion bombardment. Radiation intensities from the discharge were calculated using the determined intrinsic discharge parameters, and the results were compared with those measured for the respective panel conditions used in the calculations, yielding a fair agreement. The luminous efficiency, defined as the radiation intensity divided by the discharge power, was also determined using the intrinsic discharge parameters. Discussion on the luminous efficiency change for different panel operating conditions revealed that the efficiency improvement at a lower voltage was attributable to a lower electron temperature for this condition.

Suzuki, Keizo; Yamamoto, Kenichi; Kajiyama, Hiroshi; Ho, Shirun; Uemura, Norihiro; Muraoka, Katsunori [Hitachi Research Laboratory, c/o Central Research Laboratory, Hitachi Ltd., 1-280, Higashi-koigakubo, Kokubunji-shi, Tokyo 185-8601 (Japan); Advanced Research Laboratory, c/o Central Research Laboratory, Hitachi Ltd., 1-280, Higashi-koigakubo, Kokubunji-shi, Tokyo 185-8601 (Japan); Fujitsu Hitachi Plasma Display Ltd., 1815 Tajiri, Kunitomi-cho, Higashimorokata-gun, Miyazaki-ken 880-1194 (Japan); Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan)

2004-12-01

175

30 CFR 75.900 - Low- and medium-voltage circuits serving three-phase alternating current equipment; circuit...  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Low- and medium-voltage circuits serving three-phase...STANDARDS-UNDERGROUND COAL MINES Underground Low- and Medium-Voltage Alternating Current Circuits § 75.900 Low- and medium-voltage circuits serving...

2013-07-01

176

30 CFR 77.900 - Low- and medium-voltage circuits serving portable or mobile three-phase alternating current...  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Low- and medium-voltage circuits serving portable...OF UNDERGROUND COAL MINES Low- and Medium-Voltage Alternating Current Circuits § 77.900 Low- and medium-voltage circuits serving...

2013-07-01

177

Influence of Circuit Element Parameters on Capacitance Characteristics of Silver-Zinc Storage Batteries during Charging with Asymmetric Alternating Current.  

National Technical Information Service (NTIS)

The effect of active, inductive and capacitive resistance of the elements of an asymmetric alternating current (aac) battery charger on the discharged characteristics of silver-zinc storage batteries is examined in the Russian report. It is shown that the...

M. A. Dasoyan V. V. Bayunov

1972-01-01

178

Investigations regarding quasi-stationary alternating-current arcs between parallel electrodes in the case of unsymmetrical magnetic blowing  

Microsoft Academic Search

The present investigation is concerned with alternating-current arcs which are displaced by magnetic fields that are present in the area between the electrodes. The intensity of the magnetic field decreases from one electrode to the other. The term 'quasi-stationary' is defined for the alternating-current arc as the maintenance of the discharge for an arbitrary number of semioscillations of the load

T. Koelpin

1980-01-01

179

Influence of gas mixture ratio on the luminous efficiency in surface discharge alternating current plasma display panels  

Microsoft Academic Search

The improvement of luminosity and luminous efficiency is the one of the most important tasks in alternating current plasma display panels. The influence of gas mixture ratio, Ne–Xe and He–Ne(27%)–Xe(3%), on luminosity and luminous efficiency in surface discharge alternating-current plasma display panels has been investigated. It is found that discharge power does not strongly depend on the gas mixtures, while

J. C. Ahn; T. Y. Kim; J. J. Ko; Y. Seo; G. S. Cho; E. H. Choi

2000-01-01

180

Influence of gas mixture ratio on the luminous efficiency in surface discharge alternating current plasma display panels  

Microsoft Academic Search

The improvement of luminosity and luminous efficiency is the one of the most important tasks in alternating current plasma display panels. The influence of gas mixture ratio, Ne-Xe and He-Ne(27%)-Xe(3%), on luminosity and luminous efficiency in surface discharge alternating-current plasma display panels has been investigated. It is found that discharge power does not strongly depend on the gas mixtures, while

J. C. Ahn; T. Y. Kim; J. J. Ko; Y. Seo; G. S. Cho; E. H. Choi

2000-01-01

181

Efficacy of Lidocaine lontophoresis Using Either Alternating or Direct Current in Hairless Rats.  

PubMed

The aim of this study was to determine transport of lidocaine ions through a hairless rat skin in vivo and to compare the efficacy of alternating current (AC) with that of direct current (DC) iontophoresis (IOP). We measured the concentration of lidocaine transported through a cellophane membrane or a hairless rat dorsal skin applying either AC-IOP or DC-IOP. The results revealed that lidocaine concentration increased in a time-dependent manner in vitro in both DC-IOP and AC-IOP. However, the in vivo study showed different tendencies in lidocaine concentration. In the DCIOP group, lidocaine concentration reached its maximum 20 min after current application and then decreased rapidly; the AC-IOP group showed an increase in lidocaine concentration in a timedependent manner. There were no side effects such as electrical burns in the rats. In conclusion, AC can be applied for long periods and DC for short periods, or their application time can be appropriately scheduled. Our study also suggests the mechanism by which voltage waveforms affect the skin when applied by IOP. In the future, these findings will be a solid foundation for developing various kinds of medical equipment such as scheduled drug delivery system that can easily deliver various types of drug. PMID:24146168

Nakajima, Atsushi; Wakita, Ryo; Haida, Haruka; Fukayama, Haruhisa

2013-09-30

182

Influence of crack length on crack depth measurement by an alternating current potential drop technique  

NASA Astrophysics Data System (ADS)

An alternating current potential drop (ACPD) technique is used for sizing depth of surface cracks in metallic components. Crack depth estimations are prone to large deviations when ACPD measurements are made on very shallow and finite length cracks, especially in low conducting materials such as austenitic stainless steel (SS). Detailed studies have been carried out to investigate the influence of crack length and aspect ratio (length to depth) on depth estimation by performing measurements on electric discharge machined notches with the aspect ratio in the range of 1 to 40 in SS plates. In notches with finite length, an additional path for current to flow through the surface along the length is available causing the notch depths to be underestimated. The experimentally observed deviation in notch depth estimates is explained from a simple mathematical approach using the equivalent resistive circuit model based on the additional path available for the current to flow. A scheme is proposed to accurately measure the depth of cracks with finite lengths in SS components.

Raja, Manoj K.; Mahadevan, S.; Rao, B. P. C.; Behera, S. P.; Jayakumar, T.; Raj, Baldev

2010-10-01

183

Monitoring exocytosis from single mast cells by fast voltammetry.  

PubMed

We have used fast differential ramp voltammetry with carbon-fibre electrodes to monitor exocytotic secretion in single rat mast cells. The oxidation peak and other aspects of the electrochemical profile of the substance released were similar to those of 5-hydroxytryptamine (5-HT) and the signals were increased by preloading the secretory granules with exogenous 5-HT. Metabolic blockade inhibited both visible degranulation and the electrochemical signal. For comparison, quinacrine, which is fluorescent and accumulates in secretory vesicles, was used as an alternative means of detecting secretion in single cells. The amplitude of the electrochemical signals observed during degranulation correlated well with the loss of quinacrine fluorescence. Both methods were used to record successive rounds of secretion in single mast cells in response to repeated applications of compound 48/80. PMID:1745612

Tatham, P E; Duchen, M R; Millar, J

1991-10-01

184

Alternative (non-animal) methods for cosmetics testing: current status and future prospects-2010.  

PubMed

The 7th amendment to the EU Cosmetics Directive prohibits to put animal-tested cosmetics on the market in Europe after 2013. In that context, the European Commission invited stakeholder bodies (industry, non-governmental organisations, EU Member States, and the Commission's Scientific Committee on Consumer Safety) to identify scientific experts in five toxicological areas, i.e. toxicokinetics, repeated dose toxicity, carcinogenicity, skin sensitisation, and reproductive toxicity for which the Directive foresees that the 2013 deadline could be further extended in case alternative and validated methods would not be available in time. The selected experts were asked to analyse the status and prospects of alternative methods and to provide a scientifically sound estimate of the time necessary to achieve full replacement of animal testing. In summary, the experts confirmed that it will take at least another 7-9 years for the replacement of the current in vivo animal tests used for the safety assessment of cosmetic ingredients for skin sensitisation. However, the experts were also of the opinion that alternative methods may be able to give hazard information, i.e. to differentiate between sensitisers and non-sensitisers, ahead of 2017. This would, however, not provide the complete picture of what is a safe exposure because the relative potency of a sensitiser would not be known. For toxicokinetics, the timeframe was 5-7 years to develop the models still lacking to predict lung absorption and renal/biliary excretion, and even longer to integrate the methods to fully replace the animal toxicokinetic models. For the systemic toxicological endpoints of repeated dose toxicity, carcinogenicity and reproductive toxicity, the time horizon for full replacement could not be estimated. PMID:21533817

Adler, Sarah; Basketter, David; Creton, Stuart; Pelkonen, Olavi; van Benthem, Jan; Zuang, Valérie; Andersen, Klaus Ejner; Angers-Loustau, Alexandre; Aptula, Aynur; Bal-Price, Anna; Benfenati, Emilio; Bernauer, Ulrike; Bessems, Jos; Bois, Frederic Y; Boobis, Alan; Brandon, Esther; Bremer, Susanne; Broschard, Thomas; Casati, Silvia; Coecke, Sandra; Corvi, Raffaella; Cronin, Mark; Daston, George; Dekant, Wolfgang; Felter, Susan; Grignard, Elise; Gundert-Remy, Ursula; Heinonen, Tuula; Kimber, Ian; Kleinjans, Jos; Komulainen, Hannu; Kreiling, Reinhard; Kreysa, Joachim; Leite, Sofia Batista; Loizou, George; Maxwell, Gavin; Mazzatorta, Paolo; Munn, Sharon; Pfuhler, Stefan; Phrakonkham, Pascal; Piersma, Aldert; Poth, Albrecht; Prieto, Pilar; Repetto, Guillermo; Rogiers, Vera; Schoeters, Greet; Schwarz, Michael; Serafimova, Rositsa; Tähti, Hanna; Testai, Emanuela; van Delft, Joost; van Loveren, Henk; Vinken, Mathieu; Worth, Andrew; Zaldivar, José-Manuel

2011-05-01

185

Gold nanoarray deposited using alternating current for emission rate-manipulating nanoantenna  

NASA Astrophysics Data System (ADS)

We have proposed an easy and controllable method to prepare highly ordered Au nanoarray by pulse alternating current deposition in anodic aluminum oxide template. Using the ultraviolet-visible-near-infrared region spectrophotometer, finite difference time domain, and Green function method, we experimentally and theoretically investigated the surface plasmon resonance, electric field distribution, and local density of states enhancement of the uniform Au nanoarray system. The time-resolved photoluminescence spectra of quantum dots show that the emission rate increased from 0.0429 to 0.5 ns-1 (10.7 times larger) by the existence of the Au nanoarray. Our findings not only suggest a convenient method for ordered nanoarray growth but also prove the utilization of the Au nanoarray for light emission-manipulating antennas, which can help build various functional plasmonic nanodevices.

Xue, Jiancai; Zhu, Qiangzhong; Liu, Jiaming; Li, Yinyin; Zhou, Zhang-Kai; Lin, Zhaoyong; Yan, Jiahao; Li, Juntao; Wang, Xue-Hua

2013-06-01

186

Muscle-selective block using intrafascicular high-frequency alternating current.  

PubMed

High-frequency alternating current (HFAC) applied to a peripheral nerve can reversibly block skeletal muscle contractions. We evaluated the ability of HFAC delivered via intrafascicular electrodes to selectively block activation of targeted muscles without affecting activation of other muscles. Utah slanted electrode arrays (USEAs) were implanted into the sciatic nerves of five cats, and HFAC was delivered to individual USEA electrodes. The effects of HFAC block were monitored by recording evoked electromyograms (EMGs) and three-dimensional endpoint forces. In each animal, activity evoked in targeted muscles by nerve cuff stimulation could be selectively abolished by HFAC delivered via individual USEA electrodes. Two mechanisms of blockade were evoked: selective neuromuscular blocks were achieved with 500-8000-HZ HFAC, and selective nerve conduction block was achieved in one animal using 16-kHZ HFAC. These results show that intrafascicular HFAC can be used to block selected muscles independent of activation of other muscles. PMID:20806397

Dowden, Brett R; Wark, Heather A C; Normann, Richard A

2010-09-01

187

Rapid reversible superhydrophobicity-to-superhydrophilicity transition on alternating current etched brass.  

PubMed

Reversible surface wetting behavior is a hot topic of research because of the potential engineering applications. In the present work, a hierarchical micro/nanostructure is fabricated on brass by alternate current (AC) etching. The superhydrophilic as-prepared etched brass (EB) turns into superhydrophobic after the modification of stearic acid for 1 min. After annealing at 350 °C for 5 min, the superhydrophobic modified EB surface becomes superhydrophilic again. Furthermore, the annealed EB can restore the superhydrophobicity with the remodification of stearic acid. The wetting transition is realized by stearic acid modification and annealing rapidly in 6 min. The wetting transition mechanism is discussed based on the surface chemical analysis. This method is facile and suitable for the construction of large-scale and complex brass surfaces with tunable wetting behaviors. PMID:23627251

Wang, Zhiwei; Zhu, Liqun; Li, Weiping; Liu, Huicong

2013-05-28

188

Thermomigration in Pb-free SnAg solder joint under alternating current stressing  

NASA Astrophysics Data System (ADS)

Lead-free solders have been adopted by the microelectronics industry. However, their thermomigration behaviors are unclear. Thermomigration in eutectic SnAg3.5 solder joints was investigated using an alternating current (ac) of 0.57 A at 100 °C. The ac eliminates the electromigration effect and creates a thermal gradient of 2829 °C/cm, facilitating the study of thermomigration. Arrays of tiny markers fabricated by a focused ion beam are employed to measure the thermomigration rate. It is found that Sn atoms migrated toward the hot end. The thermomigration flux and molar heat of transport are measured to be 5.0×1012 atoms/cm2 and 1.36 kJ/mole, respectively.

Hsiao, Hsiang-Yao; Chen, Chih

2009-03-01

189

Emission characteristics in solution-processed asymmetric white alternating current field-induced polymer electroluminescent devices  

NASA Astrophysics Data System (ADS)

In this work, the emission characteristics of a blue fluorophor poly(9, 9-dioctylfluorene) (PFO) combined with a red emitting dye: Bis(2-methyl-dibenzo[f,h]quinoxaline)(acetylacetonate)iridium (III) [Ir(MDQ)2(acac)], are examined in two different asymmetric white alternating current field-induced polymer electroluminescent (FIPEL) device structures. The first is a top-contact device in which the triplet transfer is observed resulting in the concentration-dependence of the emission similar to the standard organic light-emitting diode (OLED) structure. The second is a bottom-contact device which, however, exhibits concentration-independence of emission. Specifically, both dye emission and polymer emission are found for the concentrations as high as 10% by weight of the dye in the emitter. We attribute this to the significant different carrier injection characteristics of the two FIPEL devices. Our results suggest a simple and easy way to realize high-quality white emission.

Chen, Yonghua; Xia, Yingdong; Smith, Gregory M.; Gu, Yu; Yang, Chuluo; Carroll, David L.

2013-01-01

190

Gold nanoarray deposited using alternating current for emission rate-manipulating nanoantenna.  

PubMed

We have proposed an easy and controllable method to prepare highly ordered Au nanoarray by pulse alternating current deposition in anodic aluminum oxide template. Using the ultraviolet-visible-near-infrared region spectrophotometer, finite difference time domain, and Green function method, we experimentally and theoretically investigated the surface plasmon resonance, electric field distribution, and local density of states enhancement of the uniform Au nanoarray system. The time-resolved photoluminescence spectra of quantum dots show that the emission rate increased from 0.0429 to 0.5 ns-1 (10.7 times larger) by the existence of the Au nanoarray. Our findings not only suggest a convenient method for ordered nanoarray growth but also prove the utilization of the Au nanoarray for light emission-manipulating antennas, which can help build various functional plasmonic nanodevices. PMID:23799880

Xue, Jiancai; Zhu, Qiangzhong; Liu, Jiaming; Li, Yinyin; Zhou, Zhang-Kai; Lin, Zhaoyong; Yan, Jiahao; Li, Juntao; Wang, Xue-Hua

2013-06-24

191

Optoelectronic Characteristics of Direct-Current and Alternating-Current White Thin-Film Light-Emitting Diodes Based on Hydrogenated Amorphous Silicon Nitride Film  

Microsoft Academic Search

Direct-current and alternating-current white thin- film light-emitting diodes (DCW and ACW TFLEDs) have been fabricated and demonstrated with the intrinsic hydrogenated amorphous silicon nitride (i-a-SiN:H) film as the luminescent layer. The achievable brightness of the representative DCW and ACW TFLEDs were 200 and 170 cd\\/m2 at an injection-current density of 600 and 100 mA\\/cm2, respectively. The electroluminescence (EL) threshold voltage

Rong-Hwei Yeh; Tai-Rong Yu; Te-Cheng Chung; Shih-Yung Lo; Jyh-Wong Hong

2008-01-01

192

Vaginal irritation models: the current status of available alternative and in vitro tests.  

PubMed

Mucosal surfaces, such as the vaginal epithelium, are natural barriers to infection that are constantly exposed to bacteria and viruses, and are therefore potential sites of entry for numerous pathogens. The vaginal epithelium can be damaged mechanically, e.g. by the incorrect use of objects such as tampons, and by chemicals that are irritating or corrosive. Consequently, this can lead to an increase in susceptibility to further damage or infection. Pharmaceutical, cosmetic and personal care products that are specifically formulated for application onto human external mucosae can occasionally induce undesirable local or systemic side-effects. Therefore, the compatibility of applied materials with this mucosal surface represents a key issue to be addressed by manufacturers. The most frequently used method for assessing vaginal mucosal irritation is the in vivo rabbit vaginal irritation test. However, the current emphasis in the field of toxicology is to use alternative in vitro methods that reduce, refine, and replace the use of animals, and which model and predict human, not animal, responses. Such an approach is of particular interest to the personal care and cosmetic industries in their effort to comply with European legislative measures, such as the 7th Amendment to the EU Cosmetics Directive that does not permit the marketing of cosmetic products if they, or their ingredients, have been tested for irritation responses in animals. The focus of this review is to provide an overview of the alternative and in vitro tests that are currently available for vaginal mucosal irritation assessment, and which are already used, or may become useful, to establish the safety of newly-designed products for human use. PMID:21942546

Costin, Gertrude-Emilia; Raabe, Hans A; Priston, Robert; Evans, Eric; Curren, Roger D

2011-09-01

193

Regional economic analysis of current and proposed management alternatives for Rappahannock River Valley National Wildlife Refuge  

USGS Publications Warehouse

The National Wildlife Refuge System Improvement Act of 1997 requires all units of the National Wildlife Refuge System to be managed under a Comprehensive Conservation Plan. The Comprehensive Conservation Plan must describe the desired future conditions of a refuge and provide long-range guidance and management direction to achieve refuge purposes. The Rappahannock River Valley National Wildlife Refuge (refuge) is in the process of developing a range of management goals, objectives, and strategies for the Comprehensive Conservation Plan. The Comprehensive Conservation Plan for the refuge must contain an analysis of expected effects associated with current and proposed refuge management strategies. The purpose of this study was to assess the regional economic implications associated with draft Comprehensive Conservation Plan management strategies. Special interest groups and local residents often criticize a change in refuge management, especially if there is a perceived negative impact to the local economy. Having objective data on economic impacts may show that these fears are overstated. Quite often, the extent of economic benefits a refuge provides to a local community is not fully recognized, yet at the same time the effects of negative changes is overstated. Spending associated with refuge recreational activities, such as wildlife viewing and hunting, can generate considerable tourist activity for surrounding communities. Additionally, refuge personnel typically spend considerable amounts of money purchasing supplies in local stores, repairing equipment and purchasing fuel at the local service stations, and reside and spend their salaries in the local community. For refuge Comprehensive Conservation Plan planning, a regional economic assessment provides a means of estimating how current management (no action alternative) and proposed management activities (alternatives) could affect the local economy. This type of analysis provides two critical pieces of information: (1) it illustrates a refuge's contribution to the local community; and (2) it can help in determining whether local economic effects are or are not a real concern in choosing among management alternatives. It is important to note that the economic value of a refuge encompasses more than just the impacts of the regional economy. Refuges also provide substantial nonmarket values (values for items not exchanged in established markets), such as maintaining endangered species, preserving wetlands, educating future generations, and adding stability to the ecosystem. However, quantifying these types of nonmarket values was beyond the scope of this study because of time and budget constraints.

Koontz, Lynne; Sexton, Natalie; Donovan, Ryan

2009-01-01

194

An Analysis of Alternatives to New York City's Current Marijuana Arrest and Detention Policy.  

PubMed

During the 1990s, the New York Police Department (NYPD) instituted a policy of arresting and detaining people for minor offenses that occur in public as part of their quality-of-life (hereafter QOL) policing initiative. The number of NYPD arrests for smoking marijuana in public view (MPV) increased from 3,000 in 1994 to over 50,000 in 2000, and have been about 30,000 in the mid 2000s. Most of these arrestees (84%) have been minority; blacks have been 2.7 more likely and Hispanics 1.8 times more likely to be detained than whites for an MPV arrest. Minorities have been most likely to receive more severe dispositions, even controlling for demographics and prior arrest histories.This paper examines the pros and cons of the current policy; this is compared with possible alternatives including the following: arrest and issue a desk appearance ticket (DAT); issue a non-criminal citation (violation); street warnings; and tolerate public marijuana smoking. The authors recommend that the NYPD change to issuing DATs on a routine basis. Drug policy reformers might wish to further pursue changing statutes regarding smoking marijuana in public view into a violation (noncriminal) or encourage the wider use of street warnings. Any of these policy changes would help reduce the disproportionate burden on minorities associated with the current arrest and detention policy. These policies could help maintain civic norms against smoking marijuana in public. PMID:18726007

Johnson, Bruce D; Golub, Andrew; Dunlap, Eloise; Sifaneck, Stephen J

2008-01-01

195

An Analysis of Alternatives to New York City's Current Marijuana Arrest and Detention Policy  

PubMed Central

During the 1990s, the New York Police Department (NYPD) instituted a policy of arresting and detaining people for minor offenses that occur in public as part of their quality-of-life (hereafter QOL) policing initiative. The number of NYPD arrests for smoking marijuana in public view (MPV) increased from 3,000 in 1994 to over 50,000 in 2000, and have been about 30,000 in the mid 2000s. Most of these arrestees (84%) have been minority; blacks have been 2.7 more likely and Hispanics 1.8 times more likely to be detained than whites for an MPV arrest. Minorities have been most likely to receive more severe dispositions, even controlling for demographics and prior arrest histories. This paper examines the pros and cons of the current policy; this is compared with possible alternatives including the following: arrest and issue a desk appearance ticket (DAT); issue a non-criminal citation (violation); street warnings; and tolerate public marijuana smoking. The authors recommend that the NYPD change to issuing DATs on a routine basis. Drug policy reformers might wish to further pursue changing statutes regarding smoking marijuana in public view into a violation (noncriminal) or encourage the wider use of street warnings. Any of these policy changes would help reduce the disproportionate burden on minorities associated with the current arrest and detention policy. These policies could help maintain civic norms against smoking marijuana in public.

Johnson, Bruce D.; Golub, Andrew; Dunlap, Eloise; Sifaneck, Stephen J.

2008-01-01

196

Alternating current electrophoretic deposition (EPD) of TiO2 nanoparticles in aqueous suspensions.  

PubMed

TiO(2)-nanostructured coatings from aqueous suspensions have been successfully prepared by the application of alternating current (AC) instead of direct current (DC) during electrophoretic deposition (EPD). No organic additives in suspension were required for successful EPD. The quality of the AC-EPD TiO(2) coatings in terms of homogeneity and extent of microcracking, upon drying, observed by SEM, was superior to that of DC-EPD coatings made from the same type of suspensions. The main difference between AC- and DC-EPD was the suppression of bubble formation. The absence of water electrolysis at the electrodes can be explained by the particular distribution of the electric field during AC mode, which prevents the nucleation of bubbles. The preparation of TiO(2) coatings from aqueous suspension and without the aid of organic stabilizers opens the possibility for co-deposition of sensitive materials such as biomolecules and even cells for biomedical applications, given the high biocompatibility of TiO(2). The deposition of TiO(2) coatings from aqueous suspensions is also attractive from environmental and economical points of view. PMID:22429587

Chávez-Valdez, A; Herrmann, M; Boccaccini, A R

2012-03-03

197

Air pollution control residues from waste incineration: current UK situation and assessment of alternative technologies.  

PubMed

Current disposal options for APC residues in the UK and alternative treatment technologies developed world-wide have been reviewed. APC residues are currently landfilled in the UK where they undergo in situ solidification, although the future acceptability of this option is uncertain because the EU waste acceptance criteria (WAC) introduce strict limits on leaching that are difficult to achieve. Other APC residue treatment processes have been developed which are reported to reduce leaching to below relevant regulatory limits. The Ferrox process, the VKI process, the WES-PHix process, stabilisation/solidification using cementitious binders and a range of thermal treatment processes are reviewed. Thermal treatment technologies convert APC residues combined with other wastes into inert glass or glass-ceramics that encapsulate heavy metals. The waste management industry will inevitably use the cheapest available option for treating APC residues and strict interpretation and enforcement of waste legislation is required if new, potentially more sustainable technologies are to become commercially viable. PMID:18093820

Rani, D Amutha; Boccaccini, A R; Deegan, D; Cheeseman, C R

2008-02-21

198

Two-dimensional particle simulation of a sustained discharge in an alternating current plasma display panel  

NASA Astrophysics Data System (ADS)

A plasma discharge due to a sustaining pulse of an alternating current plasma display panel was analyzed using a two-dimensional particle-in-cell code, and basic characteristics of the plasma discharge were calculated. The characteristics of the plasma discharge due to a sustaining pulse are as follows. (i) A large amount of space charge remained after drawing the discharge current. This excess space charge did not contribute to wall charge formation or ultraviolet radiation. (ii) The electron energy distribution function was evaluated and could be well fitted by the Druyvesteyn distribution in the high-energy region. The Druyvesteyn distribution was a consequence of the cross section for electron-Ne elastic scattering. (iii) The calculated ultraviolet radiation efficiency ? of the plasma discharge due to a sustaining pulse was between 5.51% and 30.7%. Examination of the sensitivity of the efficiency to the electron temperature showed that reducing the electron temperature was a key to improving the efficiency. (iv) A detailed understanding of the conditions for a stable plasma discharge, memory margin, firing voltage, and electrode voltage of the sustaining pulse were obtained from the voltage transfer curve. The voltage transfer curve could be used to optimize the discharge cell design.

Ikeda, Y.; Suzuki, K.; Fukumoto, H.; Verboncoeur, J. P.; Christenson, P. J.; Birdsall, C. K.; Shibata, M.; Ishigaki, M.

2000-12-01

199

Electroencephalograms and physical reflexes of broilers after electrical waterbath stunning using an alternating current.  

PubMed

Stunning efficiency of broilers after electrical waterbath stunning with an alternating current was assessed using electroencephalograms (EEG) and physical reflexes. Four hundred eighty-nine broilers (246 males and 243 females) were stunned in an electrical waterbath with a rectangular alternating stunning current of 60, 80, 100, 120, and 150 mA and frequencies of 70, 100, 200, 400, 800, and 1,500 Hz. Stunning time was 10 s. The EEG was recorded for 120 s poststun. Occurrence of spontaneous breathing, eye blinking, and wing flapping and the corneal reflex were recorded. The EEG was analyzed regarding the occurrence of a profound suppression to less than 10% of the prestun level in the 2 to 30-Hz band and 13 to 30-Hz band. The occurrence of epileptiform patterns was assessed and the occurrence of clonic-tonic convulsions was recorded. Statistical analysis showed a highly significant effect of stunning frequency and stunning current for all groups in the EEG analysis. Stunning frequencies above 400 Hz or below 100 mA did not result in profound suppression of brain power to less than 10% of the prestun level in more than 90% of the broilers and can therefore not be recommended. More than 80% of the birds stunned with 70 or 100 Hz at 100 mA or 70, 100, and 200 Hz with 120 and 150 mA did not recover from stunning. The occurrence of epileptiform activity could only be observed in a few birds. It is assumed that this is due to the long stunning time of 10 s and epileptiform activity could have occurred just before EEG recording started. A maximum of 30% of birds with corneal reflexes and spontaneous eye blinking should not be exceeded, whereas at 15 s poststun, not more than 15% of birds should show spontaneous eye blinking. Wing flapping occurred in at least 50% of birds with adequate stunning results. This seems to be related to convulsions and could cause meat quality defects. PMID:20460673

Prinz, S; Van Oijen, G; Ehinger, F; Coenen, A; Bessei, W

2010-06-01

200

The Inequity in Illinois School Finance. An Analysis of: The Current Situation, the Historical Record, and Alternative Solutions. Second Edition.  

ERIC Educational Resources Information Center

|This report provides an analysis of current inequities in school finance in Illinois, the historical roots of those inequities, and an analysis of alternative options for funding primary and secondary education. An introduction briefly describes the basis for the constitutional challenge to the current funding system. The next section describes…

Hess, G. Alfred, Jr.; And Others

201

Global modeling of a dielectric barrier discharge in Ne–Xe mixtures for an alternating current plasma display panel  

Microsoft Academic Search

A global model of a dielectric barrier discharge in Ne–Xe mixtures for an alternating current plasma display panel was developed. This model was used to evaluate electron temperature, plasma density, densities of excited state atoms, wall charge density, current density, excimer density, and vacuum ultraviolet (VUV) intensity, and their gas composition-pressure dependencies, in order to analyze the mechanism of VUV

Y. Ikeda; J. P. Verboncoeur; P. J. Christenson; C. K. Birdsall

1999-01-01

202

Global modeling of a dielectric barrier discharge in Ne-Xe mixtures for an alternating current plasma display panel  

Microsoft Academic Search

A global model of a dielectric barrier discharge in Ne-Xe mixtures for an alternating current plasma display panel was developed. This model was used to evaluate electron temperature, plasma density, densities of excited state atoms, wall charge density, current density, excimer density, and vacuum ultraviolet (VUV) intensity, and their gas composition-pressure dependencies, in order to analyze the mechanism of VUV

Y. Ikeda; J. P. Verboncoeur; P. J. Christenson; C. K. Birdsall

1999-01-01

203

Transcranial alternating current stimulation modulates large-scale cortical network activity by network resonance.  

PubMed

Transcranial direct current stimulation (tDCS) has emerged as a potentially safe and effective brain stimulation modality that alters cortical excitability by passing a small, constant electric current through the scalp. tDCS creates an electric field that weakly modulates the membrane voltage of a large number of cortical neurons. Recent human studies have suggested that sine-wave stimulation waveforms [transcranial alternating current stimulation (tACS)] represent a more targeted stimulation paradigm for the enhancement of cortical oscillations. Yet, the underlying mechanisms of how periodic, weak global perturbations alter the spatiotemporal dynamics of large-scale cortical network dynamics remain a matter of debate. Here, we simulated large-scale networks of spiking neuron models to address this question in endogenously rhythmic networks. We identified distinct roles of the depolarizing and hyperpolarizing phases of tACS in entrainment, which entailed moving network activity toward and away from a strong nonlinearity provided by the local excitatory coupling of pyramidal cells. Together, these mechanisms gave rise to resonance dynamics characterized by an Arnold tongue centered on the resonance frequency of the network. We then performed multichannel extracellular recordings of multiunit firing activity during tACS in anesthetized ferrets (Mustela putoris furo), a model species with a gyrencephalic brain, to verify that weak global perturbations can selectively enhance oscillations at the applied stimulation frequency. Together, these results provide a detailed mechanistic understanding of tACS at the level of large-scale network dynamics and support the future design of activity-dependent feedback tACS paradigms that dynamically tailor stimulation frequency to the spectral peak of ongoing brain activity. PMID:23825429

Ali, Mohsin M; Sellers, Kristin K; Fröhlich, Flavio

2013-07-01

204

Application of N- and B-doped CVD diamond layers for cyclic voltammetry measurements  

Microsoft Academic Search

Conductive polycrystalline diamond layers prepared by the CVD process have received attention from electrochemists owing to such superior electrochemical properties as the wide potential window, the very low background current, the stability of chemical and physical properties.In this paper, the cyclic voltammetry application using N- and B-doped diamond electrodes was studied. Diamond layers, doped with boron and nitrogen, were synthesized

R. Torz-Piotrowska; A. Wrzyszczynski; K. Paprocki; E. Staryga

2009-01-01

205

The Rise of Voltammetry: From Polarography to the Scanning Electrochemical Microscope  

ERIC Educational Resources Information Center

|The drooping mercury electrode (DME) was previously used to carry out electrochemical experiments but invention of polarography technique changed this. Voltammetry with DME was given the term polarography and are used in measurement of current as a function of potential at small electrodes.|

Bard, Allen J.

2007-01-01

206

Reduction in fatigue failures through crack detection by alternating current field measurement  

SciTech Connect

Once a crack is initiated by cyclic stress in a drillstring component, it will grow under further service loading and will fail when insufficient uncracked material remains to carry the applied load. Because the levels of cyclic and subsequent stress in drilling may be unknown (or unknowable), the drilling equipment supplier`s main defense against component fatigue failure (after design) is detection of the initial crack, conventionally by magnetic-particle or dye-penetrant inspection (respectively, MPI or DPI). A clean bill of health from MPI or DPI means only that no crack indications were found. The likely locations of cracks (e.g., thread roots in box connections) are often difficult to examine. Detection and interpretation are subjective and depend on the skill of the inspector. A crack and a surface defect may be indistinguishable from one another. No reviewable evidence of component inspection is left to allow an audit of inspection previously performed. Alternating current field measurement (ACFM) induces a current in the surface of a component. If ACFM detects a perturbation in the magnetic field created in the free space above the surface, a surface defect is present. ACFM is able to determine the length and depth of a defect. It does not require a clear line of sight between operator and crack location. All data are recorded electronically and the evidence for the existence or nonexistence of a crack can be revisited. the paper describes the theory of the technique, the equipment used, and practical results from the first application of ACFM to downhole motor components.

Gaynor, T.M.; Roberts, D.L.; Homan, E.; Dover, W.

1997-03-01

207

Comparison of direct and alternating current vacuum ultraviolet lamps in atmospheric pressure photoionization.  

PubMed

A direct current induced vacuum ultraviolet (dc-VUV) krypton discharge lamp and an alternating current, radio frequency (rf) induced VUV lamp that are essentially similar to lamps in commercial atmospheric pressure photoionization (APPI) ion sources were compared. The emission distributions along the diameter of the lamp exit window were measured, and they showed that the beam of the rf lamp is much wider than that of the dc lamp. Thus, the rf lamp has larger efficient ionization area, and it also emits more photons than the dc lamp. The ionization efficiencies of the lamps were compared using identical spray geometries with both lamps in microchip APPI mass spectrometry (?APPI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). A comprehensive view on the ionization was gained by studying six different ?APPI solvent compositions, five DAPPI spray solvents, and completely solvent-free DAPPI. The observed reactant ions for each solvent composition were very similar with both lamps except for toluene, which showed a higher amount of solvent originating oxidation products with the rf lamp than with the dc lamp in ?APPI. Moreover, the same analyte ions were detected with both lamps, and thus, the ionization mechanisms with both lamps are similar. The rf lamp showed a higher ionization efficiency than the dc lamp in all experiments. The difference between the lamp ionization efficiencies was greatest when high ionization energy (IE) solvent compositions (IEs above 10 eV), i.e., hexane, methanol, and methanol/water, (1:1 v:v) were used. The higher ionization efficiency of the rf lamp is likely due to the larger area of high intensity light emission, and the resulting larger efficient ionization area and higher amount of photons emitted. These result in higher solvent reactant ion production, which in turn enables more efficient analyte ion production. PMID:22229729

Vaikkinen, Anu; Haapala, Markus; Kersten, Hendrik; Benter, Thorsten; Kostiainen, Risto; Kauppila, Tiina J

2012-01-23

208

Transcranial Alternating Current Stimulation Increases Risk-Taking Behavior in the Balloon Analog Risk Task  

PubMed Central

The process of evaluating risks and benefits involves a complex neural network that includes the dorsolateral prefrontal cortex (DLPFC). It has been proposed that in conflict and reward situations, theta-band (4–8?Hz) oscillatory activity in the frontal cortex may reflect an electrophysiological mechanism for coordinating neural networks monitoring behavior, as well as facilitating task-specific adaptive changes. The goal of the present study was to investigate the hypothesis that theta-band oscillatory balance between right and left frontal and prefrontal regions, with a predominance role to the right hemisphere (RH), is crucial for regulatory control during decision-making under risk. In order to explore this hypothesis, we used transcranial alternating current stimulation, a novel technique that provides the opportunity to explore the functional role of neuronal oscillatory activities and to establish a causal link between specific oscillations and functional lateralization in risky decision-making situations. For this aim, healthy participants were randomly allocated to one of three stimulation groups (LH stimulation/RH stimulation/Sham stimulation), with active AC stimulation delivered in a frequency-dependent manner (at 6.5?Hz; 1?mA peak-to-peak). During the AC stimulation, participants performed the Balloon Analog Risk Task. This experiment revealed that participants receiving LH stimulation displayed riskier decision-making style compared to sham and RH stimulation groups. However, there was no difference in decision-making behaviors between sham and RH stimulation groups. The current study extends the notion that DLPFC activity is critical for adaptive decision-making in the context of risk-taking and emphasis the role of theta-band oscillatory activity during risky decision-making situations.

Sela, Tal; Kilim, Adi; Lavidor, Michal

2011-01-01

209

Alternating-current induced thermal fatigue of gold interconnects with nanometer-scale thickness and width.  

PubMed

With dramatic reduction in sizes of microelectronic devices, the characteristic width and thickness of interconnects in large-scale integrated circuits have reached nanometer scale. Thermal fatigue damage of so small interconnects has attracted more and more attentions. In this work, thermal fatigue of Au interconnects, 35 nm thick and 0.1-5 ?m wide, is investigated by applying various alternating current densities to generate cycling temperature and strain in them. A multi-probe measuring system is installed in a scanning electron microscope and a probe-type temperature sensor is for the first time introduced into the system for real-time measuring the temperatures on the pads of the tested interconnects. A one-dimensional heat conduction equation, which uses measured temperatures on the pads as boundary conditions and includes a term of heat dissipation through the interface between the interconnect and the oxidized silicon substrate, is proposed to calculate the time-resolved temperature distribution along the Au interconnects. The measured fatigue lifetimes are presented versus current density and thermal cyclic strain, and the results show that narrower Au lines are more reliable. The failure mechanism of those Au interconnects differs from what is observed in thick interconnects with relatively larger grain size. Topography change caused by localized plasticity on the less-constrained surfaces of the interconnects have not been observed. Instead, grain growing and reorienting due to local temperature varying appear, and grain boundary migration and mergence take place during high temperature fatigue in such thin and narrow interconnects. These results seem to reflect a strain-induced boundary migration mechanism, and the damage morphology also suggests that fatigue of the interconnects with decreased grain size and film thickness is controlled by diffusive mechanisms and interface properties rather than by dislocation glide. Open circuit eventually took place by melting at a region of severely damage cross-sectional area with the grain growing and reorienting. PMID:22047308

Sun, Lijuan; Ling, Xue; Li, Xide

2011-10-01

210

Molecular stretching of long DNA in agarose gel using alternating current electric fields.  

PubMed Central

We demonstrate a novel method for stretching a long DNA molecule in agarose gel with alternating current (AC) electric fields. The molecular motion of a long DNA (T4 DNA; 165.6 kb) in agarose gel was studied using fluorescence microscopy. The effects of a wide range of field frequencies, field strengths, and gel concentrations were investigated. Stretching was only observed in the AC field when a frequency of approximately 10 Hz was used. The maximal length of the stretched DNA had the longest value when a field strength of 200 to 400 V/cm was used. Stretching was not sensitive to a range of agarose gel concentrations from 0.5 to 3%. Together, these experiments indicate that the optimal conditions for stretching long DNA in an AC electric field are a frequency of 10 Hz with a field strength of 200 V/cm and a gel concentration of 1% agarose. Using these conditions, we were able to successfully stretch Saccharomyces cerevisiae chromosomal DNA molecules (225-2,200 kb). These results may aid in the development of a novel method to stretch much longer DNA, such as human chromosomal DNA, and may contribute to the analysis of a single chromosomal DNA from a single cell.

Kaji, Noritada; Ueda, Masanori; Baba, Yoshinobu

2002-01-01

211

Demagnetization Treatment of Remanent Composite Microspheres Studied by Alternating Current Susceptibility Measurements  

PubMed Central

The magnetic remanence of silica microspheres with a low concentration of embedded cobalt ferrite nanoparticles is studied after demagnetization and remagnetization treatments. When the microspheres are dispersed in a liquid, alternating current (AC) magnetic susceptibility spectra reveal a constant characteristic frequency, corresponding to the rotational diffusion of the microparticles; this depends only on particle size and liquid viscosity, making the particles suitable as a rheological probe and indicating that interactions between the microspheres are weak. On the macroscopic scale, a sample with the dry microparticles is magnetically remanent after treatment in a saturating field, and after a demagnetization treatment, the remanence goes down to zero. The AC susceptibility of a liquid dispersion, however, characterizes the remanence on the scale of the individual microparticles, which does not become zero after demagnetization. The reason is that an individual microparticle contains only a relatively small number of magnetic units, so that even if they can be reoriented magnetically at random, the average vector sum of the nanoparticle dipoles is not negligible on the scale of the microparticle. In contrast, on the macroscopic scale, the demagnetization procedure randomizes the orientations of a macroscopic number of magnetic units, resulting in a remanent magnetization that is negligible compared to the saturation magnetization of the entire sample.

van Berkum, Susanne; Erne, Ben H.

2013-01-01

212

Demagnetization treatment of remanent composite microspheres studied by alternating current susceptibility measurements.  

PubMed

The magnetic remanence of silica microspheres with a low concentration of embedded cobalt ferrite nanoparticles is studied after demagnetization and remagnetization treatments. When the microspheres are dispersed in a liquid, alternating current (AC) magnetic susceptibility spectra reveal a constant characteristic frequency, corresponding to the rotational diffusion of the microparticles; this depends only on particle size and liquid viscosity, making the particles suitable as a rheological probe and indicating that interactions between the microspheres are weak. On the macroscopic scale, a sample with the dry microparticles is magnetically remanent after treatment in a saturating field, and after a demagnetization treatment, the remanence goes down to zero. The AC susceptibility of a liquid dispersion, however, characterizes the remanence on the scale of the individual microparticles, which does not become zero after demagnetization. The reason is that an individual microparticle contains only a relatively small number of magnetic units, so that even if they can be reoriented magnetically at random, the average vector sum of the nanoparticle dipoles is not negligible on the scale of the microparticle. In contrast, on the macroscopic scale, the demagnetization procedure randomizes the orientations of a macroscopic number of magnetic units, resulting in a remanent magnetization that is negligible compared to the saturation magnetization of the entire sample. PMID:24009021

van Berkum, Susanne; Erné, Ben H

2013-09-04

213

Manipulating single annealed polyelectrolyte under alternating current electric fields: Collapse versus accumulation  

PubMed Central

Effective manipulation and understanding of the structural and dynamic behaviors of a single polyelectrolyte (PE) under alternating current (AC) electric fields are of great scientific and technological importance because of its intimate relevance to emerging bionanotechnology. In this work, we employ fluorescence correlation spectroscopy (FCS) to study the conformational and AC-electrokinetic behaviors of a model annealed PE, poly(2-vinyl pyridine) (P2VP) under both spatially uniform and non-uniform AC fields at a single molecule level. Under spatially uniform AC-fields, we observe a gradual and continuous coil-to-globule conformational transition (CGT) of single P2VP at varied AC-frequency when a critical AC-field strength is exceeded, in contrast to the pH-induced abrupt CGT in the absence of AC-fields. On the contrary, under spatially non-uniform AC-fields, we observe field-driven net flow and accumulation of P2VP near high AC-field regions due to combined AC electro-osmosis and dielectrophoresis but surprisingly no conformational change. Thus, distinct AC-electric polarization effect on single annealed PE subject to AC-field homogeneity is suggested.

Wang, Shengqin; Zhu, Yingxi

2012-01-01

214

Application of broadband alternating current magnetic susceptibility to the characterization of magnetic nanoparticles in natural materials  

NASA Astrophysics Data System (ADS)

A new method is proposed for characterizing magnetic particles by measuring low-field alternating current magnetic susceptibility at a number of frequency steps spanning four orders of magnitude, from 125 Hz to 512 kHz. This method was tested using natural samples with various grain size distributions, including basalt (Kilauea, Hawaii), loess and paleosol (Luochuan, China), tuff (Yucca Mountain, Nevada), granite (Minnesota Valley, Minnesota), and andesite (Sakurajima, Japan). The resulting frequency spectrum of magnetic susceptibility (FSMS) of the basalt, loess/paleosol, and tuff decreases with increasing frequency, but at different rates of decrease. The FSMS of the basalt is characterized by a monotonic decrease with increasing frequency over the entire range. The FSMS of the loess/paleosol and the tuff decreases more markedly than that of the basalt, which agrees with previous results showing that superparamagnetic particles are dominant in such material. Quantitative estimates using FSMSs allow reconstruction of characteristic grain size distributions and clearly identify differences in the distribution of superparamagnetic particles. The multidomain granite sample has no distinct frequency dependence, which is probably due to the smooth displacement of domain walls in the presence of the external field. In contrast, the FSMSs of the andesite samples exhibit maxima over a limited frequency range, between 16 and 128 kHz. This behavior, together with low-temperature measurements, can be accounted for by magnetic resonance of domain walls in the multidomain phenocrysts.

Kodama, Kazuto

2013-01-01

215

Alternative solutions to the current situation of oocyte donation in Singapore.  

PubMed

The rising incidence of age-related female infertility in Singapore, coupled with the prohibition on commercialized oocyte donation and egg sharing, has resulted in a severe shortage of donor oocytes. Infertile women are routinely encouraged by fertility doctors here to seek their close relatives and friends as prospective oocyte donors, which does not alleviate the shortage. A number of alternative solutions are discussed. The use of substantial financial remuneration to encourage oocyte donation is rejected as being legally, ethically and morally incompatible with present day Singaporean society. Egg sharing in return for subsidized fertility may have a strong case for ethical justification, but implementation would need amendment of the current legislation in Singapore. Cross- and mirror-exchange oocyte donations face less of a legal challenge in Singapore and also have a strong case for ethical justification. However, special consideration must be given to the unique socio-cultural values of Singaporean society, i.e. traditional Chinese culture. Finally, if no changes are made to restrictive regulations governing oocyte donation in Singapore, and shortage of donor oocytes still persists, then reproductive tourism abroad may be the solution for some patients; referrals by local fertility doctors are unlikely to be allowed in Singapore. PMID:16569312

Heng, Boon Chin

2006-03-01

216

Alteration of Membrane Permeability of Bacteria and Yeast by High Frequency Alternating Current (HFAC)  

PubMed Central

Aims: Endox® Endodontic System (Endox) is used for endodontic treatment by a high frequency alternating current (HFAC). This device damaged the envelopes of spores and vegetative organisms. If the integrity of the envelope is compromised, the transit of compounds in the two directions is possible. This latter aspect was investigated here. Methods: The instrument delivered a 60ms pulse at a frequency 300 kHz, and power 800 KV/m. DNA transfer was verified using Escherichia coli K-12 strain carrying a non conjugative plasmid pBP517 (gyrA+) as donor and a rifampicin and nalidixic acid resistant recipient. 0.2 ml of mixture of donor and recipient strains in saline was exposed to HFAC and plated on selective media. Uptake of antimicrobials and a delay in re-growth was assessed exposing the strains to HFAC. Results: Plasmid transfer was detected under different experimental conditions. From 9 to 27 recombinants were found. Representative recombinants cured from plasmid showed the original phenotype. HFAC promoted the uptake of ineffective antibiotics, and induces a 1 h of delay in re-growth on the strains. Conclusions: Endox exhibited an effect on microrganisms which is reminiscent with that occuring in electroporation, but with a mode of action that saved materials and time.

Cassanelli, C; Marchese, A; Cagnacci, S; Debbia, E.A

2008-01-01

217

Thin-film alternating current nanocalorimeter for low temperatures and high magnetic fields  

NASA Astrophysics Data System (ADS)

Thin-film nanocalorimeter for low temperatures and high magnetic fields is described. The calorimeter is based on a commercial microchip module (thermal conductivity vacuum gauge TCG 3880 from Xensor Integration, NL). The gauge consists of submicron silicon nitride membrane with a film-thermopile and a resistive film-heater with dimensions of 50×100 ?m2 located at the center of the membrane. The gauge is mounted in a thermostat filled with helium exchange gas. The method of alternating current (ac) calorimetry is applied for heat capacity measurements. The noise-floor sensitivity of the calorimeter is better than 1 nJ/K below 100 K and about 3 nJ/K at 300 K. This allows for reliable measurements to be performed on sub-microgram samples. It is proved that the method is applicable for heat capacity measurements at temperatures in the range of 5-300 K and in high magnetic fields up to 8 T. We present a theoretical analysis of the thermal processes in the gauge-sample-surrounding gas system. On this basis a calibration method has been developed. We demonstrate that the technique yields correct heat capacity for test samples and that in special cases the thermal conductivity and the magnetostriction of the sample can be measured simultaneously with the heat capacity.

Minakov, A. A.; Roy, S. B.; Bugoslavsky, Y. V.; Cohen, L. F.

2005-04-01

218

Manganese detection in marine sediments: anodic vs. cathodic stripping voltammetry  

Microsoft Academic Search

Three different electroanalytical techniques for the detection of manganese in marine sediments are evaluated. The anodic stripping voltammetry of manganese at an in situ bismuth-film-modified boron-doped diamond electrode and cathodic stripping voltammetry at a carbon paste electrode are shown to lack the required sensitivity and reproducibility whereas cathodic stripping voltammetry at a bare boron-doped diamond electrode is shown to be

Craig E. Banks; Jaanus Kruusma; Ryan R. Moore; Peter Tom?ík; Judith Peters; James Davis; Šebojka Komorsky-Lovri?; Richard G. Compton

2005-01-01

219

The Alternative Birth Movement in the United States: History and Current Status  

Microsoft Academic Search

The alternative birth movement is a consumer reaction to paternalistic and mechanistic medical obstetrical practices which developed in the United States early in this century. Alternative birth settings developed as single labor-delivery-recovery rooms in the hospital or as free-standing birth centers. Both alternatives offer family-centered, home-like, low technological maternity care. In order to overcome physician resistance to non-traditional maternity care,

Joan J. Mathews; Kathleen Zadak

1991-01-01

220

On the essential role of current density in electrocatalytic activity of the electrodeposited platinum for oxidation of ammonia  

Microsoft Academic Search

Fabrication by electrolytic deposition of platinum (Pt) electrocatalyst provides a promising alternative for oxidation of ammonia. This work investigated the role of current density in the electrocatalytic activity of the prepared Pt electrocatalysts by cyclic voltammetry and surface characterization. The Pt loading amount is determined by inductively coupled plasma. Results demonstrated that, the electrodeposited Pt has a much higher electrocatalytic

C. Zhong; W. B. Hu; Y. F. Cheng

2011-01-01

221

Alternating current electrical field effects on lettuce (Lactuca sativa) growing in hydroponic culture with and without cadmium contamination  

Microsoft Academic Search

The aim of the present study was to investigate the effect of a 10 Hz alternating current (10 Hz 1 V cm?1) and a 50 Hz alternating current (50 Hz 1 V cm?1) on the lettuce plant (Lactuca sativa) growing in a hydroponic (soil-free) culture. Thirty lettuce plants were pre-germinated, and then 15 of them were treated\\u000a with cadmium solution (CdCl2) of 5 mg\\/L in concentration. Ten plants (five

Ran Bi; Michael Schlaak; Eike Siefert; Richard Lord; Helen Connolly

2010-01-01

222

Voltammetry under a Controlled Temperature Gradient  

PubMed Central

Electrochemical measurements are generally done under isothermal conditions. Here we report on the application of a controlled temperature gradient between the working electrode surface and the solution. Using electrochemical sensors prepared on ceramic materials with extremely high specific heat conductivity, the temperature gradient between the electrode and solution was applied here as a second driving force. This application of the Soret phenomenon increases the mass transfer in the Nernst layer and enables more accurate control of the electrode response enhancement by a combination of diffusion and thermal diffusion. We have thus studied the effect of Soret phenomenon by cyclic voltammetry measurements in ferro/ferricyanide. The time dependence of sensor response disappears when applying the Soret phenomenon, and the complicated shape of the cyclic voltammogram is replaced by a simple exponential curve. We have derived the Cotrell-Soret equation describing the steady-state response with an applied temperature difference.

Krejci, Jan; Sajdlova, Zuzana; Krejci, Jan; Marvanek, Tomas

2010-01-01

223

Monitoring the escape of DNA from a nanopore using an alternating current signal.  

PubMed

We present the use of an alternating current (AC) signal as a means to monitor the conductance of an alpha-hemolysin (alphaHL) pore as a DNA hairpin with a polydeoxyadenosine tail is driven into and released from the pore. Specifically, a 12 base pair DNA hairpin attached to a 50-nucleotide poly-A tail (HP-A(50)) is threaded into an alphaHL channel using a DC driving voltage. Once the HP-A(50) molecule is trapped within the alphaHL channel, the DC driving voltage is turned off and the conductance of the channel is monitored using an AC voltage. The escape time, defined as the time it takes the HP-A(50) molecule to transport out of the alphaHL channel, is then measured. This escape time has been monitored as a function of AC amplitude (20 to 250 mV(ac)), AC frequency (60-200 kHz), DC drive voltage (0 to 100 mV(dc)), and temperature (-10 to 20 degrees C), in order to determine their effect on the predominantly diffusive motion of the DNA through the nanopore. The applied AC voltage used to monitor the conductance of the nanopore has been found to play a significant role in the DNA/nanopore interaction. The experimental results are described by a one-dimensional asymmetric periodic potential model that includes the influence of the AC voltage. An activation enthalpy barrier of 1.74 x 10(-19) J and a periodic potential asymmetry parameter of 0.575 are obtained for the diffusion at zero electrical bias of a single nucleotide through alphaHL. PMID:20099878

Lathrop, Daniel K; Ervin, Eric N; Barrall, Geoffrey A; Keehan, Michael G; Kawano, Ryuji; Krupka, Michael A; White, Henry S; Hibbs, Andrew H

2010-02-17

224

Evaluation of vascular wall elasticity of human digital arteries using alternating current-signal photoplethysmography  

PubMed Central

Purpose A simple method of estimating arterial elasticity in the human finger using a volume-oscillometric technique with photoplethysmography was principally studied under the various effects of age, sex, and cold-stress stimulation for testing the capability of using this technique in arterial elasticity analysis. Methods Amplitude variations in the alternating current signal of the photoplethysmograph during a continuous change in transmural pressure were analyzed to obtain the blood pressure and the transmural pressure–relative volume difference relationship of the arteries. We first tested the effect of the occluding cuff size on the arterial elasticity analysis in eight subjects (ages 20–45 years) to obtain a suitable cuff size, resulting in the selection of a middle cuff with a 22 mm diameter. Blood pressure and arterial elasticity were measured in six groups of subjects separated into three age-groups of women and men (ages 20–25, 32–45, and over 50 years) for testing the effect of age and sex. Twelve subjects (ages 20–25 years) also had their blood pressure and arterial elasticity measured in three conditions under the influence of the cold-stress stimulation. Results Age, sex, and cold-stress stimulation had an impact on mean blood pressure (P < 0.0005, 0.025), whereas pulse pressure and heart rate were statistically unchanged by those factors. Furthermore, an advanced age (over 50 years) was found to induce an increase in relative volume difference values (P < 0.025) and upward shifting of the transmural pressure–relative volume difference relationships, whereas sex, level of mean blood pressure, and cold-stress stimulation had no influence on these forms of the index. Conclusion This study showed the usefulness of the relative volume difference as being a mean blood pressure-independent indicator for changes in arterial elasticity.

Uangpairoj, Pichitra; Shibata, Masahiro

2013-01-01

225

Current Status of Conducting Alternative Testing to Mammalian Toxicity Studies in the Japan Pharmaceutical Manufacturers Association  

Microsoft Academic Search

To measure the use of alternatives to in vivo mammalian toxicity studies dur- ing drug research and development, the Japan Pharmaceutical Manufacturers Association (JPMA) distributed a questionnaire to its 99 member companies, of which 85 responded and 50 (59%) of them had some experiences in using alter- natives to in vivo mammalian toxicity studies. The results show alternative methods have

Toshiaki Matsuzawa; Akira Koda; Masaharu Hashimato; Toshiji Igarashi

1998-01-01

226

Gas-solid carbonation as a current alternative origin for carbonates in Martian regolith  

NASA Astrophysics Data System (ADS)

Carbonates are abundant sedimentary minerals at the surface and sub-surface of Earth and they have been proposed as tracers of liquid water in extraterrestrial environments (e.g. at Mars surface). Its formation mechanism is since generally associated with aqueous alteration processes. Recently, carbonates minerals have been discovered on Mars surface by different orbital or rovers missions. In particular, the phoenix mission has measured from 1 to 5% of calcium carbonate (calcite type). These occurrences have been reported in area were the relative humidity is significantly high (Boynton et al., 2009). The small concentration of carbonates suggests an alternative process than carbonation in aqueous conditions. Such an observation might rather point toward a possible formation mechanism by dust-gas reaction under current Martian conditions. For this reason, in the present study, we designed an experimental setup consisting of an infrared microscope coupled to a cryogenic reaction cell (IR-CryoCell setup) in order to investigate the gas-solid carbonation of three different mineral precursors for carbonates (Ca and Mg hydroxides, and a hydrated Ca silicate formed from Ca2SiO4) at low temperature (from -10 to 25°C) and at reduced CO2 pressure (from 100 to 1000 mbar). These mineral materials are crucial precursors to form respective Ca and Mg carbonates in humid environments (0 < relative humidity < 100%) at dust-CO2 or dust-water ice-CO2 interfaces. The results have revealed a significant and fast carbonation process for Ca hydroxide and hydrated Ca silicate. Conversely, slight carbonation process was observed for Mg hydroxide. These results suggest that gas-solid carbonation process or carbonate formation at the dust-water ice-CO2 interfaces could be a currently active Mars surface process. We note that the carbonation process at low temperature (<0°C) described in the present study could also have important implications on the dust-water ice-CO2 interactions in cold terrestrial environments (e.g. Antarctic).

Garenne, A.; Montes-Hernandez, G.; Beck, P.; Schmitt, B.; Brissaud, O.

2011-12-01

227

Gain and saturation parameter of a waveguide CO2 laser excited by a longitudinal alternating-current capacitance discharge  

Microsoft Academic Search

A determination was made of the dependencies of the small-signal gain, saturation power, and gas temperature on the discharge tube diameter, working pressure, and discharge current in a wave-guide CO2 laser excited by a longitudinal alternating-current (5 - 100 kHz) capacitance discharge. The results established that the scaling laws were applicable and a comparison was made of the efficiency of

V. V. Antyukhov; Alexander F. Glova; O. R. Kachurin; Fedor V. Lebedev; Vladimir P. Yartsev

1993-01-01

228

Gain and saturation parameter of a waveguide COâ laser excited by a longitudinal alternating-current capacitance discharge  

Microsoft Academic Search

A determination was made of the dependences of the small-signal gain, saturation power, and gas temperature on the discharge tube diameter, working pressure, and discharge current in a waveguide COâ laser excited by a longitudinal alternating-current (5--100 kHz) capacitance discharge. The results established that the scaling laws were applicable and a comparison was made of the efficiency of this excitation

V. V. Antyukhov; A. F. Glova; O. R. Kachurin; F. V. Lebedev; V. P. Yartsev

1985-01-01

229

The effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels  

Microsoft Academic Search

In this work, we studied the effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels. Through discharge current analysis, we observed that self-erase discharge occurred mainly between the sustain cathode and the address electrode, which has an influence on the luminous efficacy. We varied the amount and timing of the self-erase discharge in order to

Tae Jun Kim; Joong Kyun Kim; Jae-Chul Jung; Hae-Yoon Jung; Ki-Woong Whang

2009-01-01

230

Changes in Na + , K + concentrations in perspiration and perspiration volume with alternating current iontophoresis in palmoplantar hyperhidrosis patients  

Microsoft Academic Search

Various treatments are currently available for palmoplantar hyperhidrosis. We have treated palmoplantar hyperhidrosis patients\\u000a effectively with the use of alternating current (AC) iontophoresis. However, much remains unknown about the physiological\\u000a changes that occur with AC iontophoresis, and its mechanism of action. We measured the changes in Na+, K+ concentration in perspiration and perspiration volume with AC iontophoresis in palmoplantar hyperhidrosis

Yuichiro Ohshima; Hirokazu Shimizu; Takeshi Yanagishita; Daisuke Watanabe; Yasuhiko Tamada; Junichi Sugenoya; Takao Tsuda; Yoshinari Matsumoto

2008-01-01

231

The alternative birth movement in the United States: history and current status.  

PubMed

The alternative birth movement is a consumer reaction to paternalistic and mechanistic medical obstetrical practices which developed in the United States early in this century. Alternative birth settings developed as single labor-delivery-recovery rooms in the hospital or as free-standing birth centers. Both alternatives offer family-centered, home-like, low technological maternity care. In order to overcome physician resistance to non-traditional maternity care, alternative birth center policies eliminate all women who are expected to have a complicated pregnancy or delivery. Physician resistance to alternative birthing is publicly based on the issue of maternal and infant safety. Additional issues, however, are that physicians fear economic competition and resist loss of control over obstetric practice. This paper (1) traces the historical antecedents and social factors leading to the alternative birth movement, (2) describes the types of alternative birthing methods, and (3) describes ways in which the obstetrical community has maintained and rationalized dominance over the birthing process. PMID:2048321

Mathews, J J; Zadak, K

1991-01-01

232

Digital Simulation of Anodic Stripping Voltammetry from Thin Film Electrodes.  

National Technical Information Service (NTIS)

The anodic stripping voltammetry (ASV) is routinely applied to control of Cu(II) in heavy water in the primary cooling loop of the Nuclear Power Reactor. The anodic stripping voltammetry (ASV) is a very well-known technique in electroanalytical chemistry....

J. F. Magallanes

1984-01-01

233

Application of hollow channel between sustain electrodes to improve discharge characteristics in alternating current plasma display panels  

Microsoft Academic Search

A front-panel structure with a hollow channel between sustain electrodes for an alternating current plasma display panel is proposed to achieve a low breakdown voltage and short discharge time lag due to the strong electric field in the hollow channel. When compared with a conventional structure, the structure with a hollow channel produced a 15% firing voltage improvement, 8% minimum

Seung-Hyun Son; Yong-Suk Park; Seong-Chan Bae; Sie-Young Choi

2002-01-01

234

Influence of Ion Bombardment onto Phosphor Layer on Temporal Image Sticking in Alternating-Current Plasma Display Panel  

Microsoft Academic Search

We found that ion bombardment onto a phosphor layer during a sustained discharge was a key factor in inducing temporal image sticking of alternating-current (AC) plasma display panels (PDPs) through facilitated absorption of H2O onto the phosphor layer. We also found that ion bombardment onto the phosphor layer during the sustain discharge strongly depended on the bias conditions of the

Choon-Sang Park; Sang-Yup Kim; Eun-Young Jung; Heung-Sik Tae

2011-01-01

235

A new mixed-mode sustain method to improve the luminous efficiency of alternating current plasma display panels  

Microsoft Academic Search

In this paper, a new mixed-mode sustain method to improve the luminous efficiency of alternating current plasma display panels is proposed. An opposite discharge is initiated between successive surface sustain discharges during the sustain period. The opposite discharge not only has a higher ultraviolet photon collection factor, but also improves the surface sustain discharge efficiency for the production of ultraviolet

Shin-Tai Lo; Chern-Lin Chen

2002-01-01

236

Analytical Description of the Process of Influx of the Sample Material into an Alternating-Current Arc Discharge Plasma  

Microsoft Academic Search

Physical and mathematical models of the influx of the sample material into an alternating-current arc discharge plasma are suggested. Analytical expressions describing changes in the rate of influx of the base metal and impurities into the discharge have been derived. Experimental results on the rates of influx of elements from metal samples of gold and silver are presented. They are

E. S. Voropai; A. P. Zazhogin; K. I. Chervyakovskii

2004-01-01

237

Radiation from an alternating current high-pressure mercury discharge: A comparison between experiments and model calculations  

Microsoft Academic Search

An alternating current (ac) high-pressure mercury arc has been experimentally investigated, and the results have been compared with model calculations. In the model, only radial dependencies are considered, and a careful treatment of the radiation transport is included. The absolutely measured side-on radiance in the visible and near ultraviolet spectral range can now be quantitatively reproduced by this model starting

G. Hartel; H. Schöpp; H. Hess; L. Hitzschke

1999-01-01

238

High luminous efficiency characteristics of alternating current plasma display panel with delta color arrayed, enclosed barrier rib structure  

Microsoft Academic Search

The luminous efficiency characteristics of a new alternating current plasma display panel (ac PDP) structure with the segmented electrodes in delta color arrayed subpixels with enclosed barrier ribs (SDE) are investigated. The SDE structure which has a 4:3 horizontal to vertical cell dimension ratio showed higher luminance and luminous efficiency increment characteristics as the Xe partial pressure increased compared to

Tae Jun Kim; Cha Keun Yoon; Ki-Woong Whang

2006-01-01

239

Two-dimensional modeling of a surface type alternating current plasma display panel cell: discharge dynamics and address voltage effects  

Microsoft Academic Search

To improve the luminance and efficiency of an alternating current plasma display panel, the direct measurement of infrared and vacuum ultra violet (VUV) imaging is performed to study discharge dynamics. Images show two emission regions. One is the cathode glow and the other is the anode glow. In the course of discharge cycle, the cathode glow propagates toward the outer

Jeong Hyun Seo; Woo Joon Chung; Cha Keun Yoon; Joong Kyun Kim; Ki-Woong Whang

2001-01-01

240

NDT of on and offshore oil and gas installations using the alternating current field measurement (ACFM) technique  

Microsoft Academic Search

Offshore inspection has been carried out in the UK waters for the last 25 years, but the techniques used have until recently remained stagnant. Innovative work carried out by University College London produced the mathematical modeling of the alternating current field measurement technique, which was then further developed and commercialized into a field usable technique. During detection and sizing trials,

G. A. Raine; N. Smith

1996-01-01

241

Alternating current loss calculation in a high-TC superconducting transmission cable considering the magnetic field distribution  

Microsoft Academic Search

We have calculated the alternating current (ac) losses of a 114 MVA high-TC superconducting (HTS) transmission cable using an electric-circuit (EC) model. The HTS cable is fabricated by Tokyo Electric Power Company and Sumitomo Electric Industries, Ltd. The EC model is comprised of a resistive part and an inductive part. The resistive part is obtained by the approximated Norris equation

H. Noji; K. Haji; T. Hamada

2003-01-01

242

High-frequency harmonics generation by Bi2Sr2Ca2Cu3Oy ceramic carrying alternating transport current  

Microsoft Academic Search

We have detected the nonlinear magnetic flux generated by a superconducting slab in the presence of an alternating transport current alone, and with no external fields around during the detection. The temperature dependence of induced flux is found to be analogous in its main features to the nonlinear susceptibility: (1) only odd harmonics exist, (2) the third-harmonic signal is bell

A. M. Grishin; V. N. Korenivski; K. V. Rao; A. N. Ulyanov

1994-01-01

243

A comparative study of alternating write-current-induced pole tip protrusion in perpendicular and longitudinal recording heads  

Microsoft Academic Search

This paper presents a comparative study of alternating write-current-induced pole tip protrusions (WPTP) in perpendicular magnetic recording (PMR) and longitudinal magnetic recording (LMR) heads during writing operation. Both finite element modeling and experimental measurements were performed for this study. The results show that the writer resistance and inductance as well as the WPTP of PMR heads are all substantially lower

Suping Song; Tao Pan; Dori Fang; Kroum Stoev; Michael Ho; Sining Mao

2008-01-01

244

Complementary and Alternative Medicine: Comparison of Current Knowledge, Attitudes and Interest among German Medical Students and Doctors  

Microsoft Academic Search

Although it has been agreed that complementary and alternative medicine (CAM) should be included in the German medical curriculum, there is no consensus on which methods and how it should be taught. This study aimed to assess needs for CAM education by evaluating current knowledge, attitudes and interests of medical students, general physicians and gynecologists. Two instruments based on established

Karsten Munstedt; Hildegard Harren; Richard von Georgi; Andreas Hackethal

2008-01-01

245

Survey of Current Worldwide Research on the Thermophysical Properties of Alternative Refrigerants.  

National Technical Information Service (NTIS)

The survey represents an exhaustive compilation of the research activities throughout the world concerned with either measurements or correlations of the thermophysical properties of alternative refrigerants. The properties covered in the study include th...

M. O. McLinden W. M. Haynes J. T. R. Watson K. Watanabe

1991-01-01

246

Electrochemical impregnation of sintered nickel structures with cadmium using constant current step and alternating-current pulse techniques  

Microsoft Academic Search

Cadmium electrodes, made by impregnation of sintered nickel plaques with cadmium hydroxide by three electrochemical techniques followed by formation to cadmium, can be used as efficient electrodes in nickel-cadmium secondary cells yielding capacities as high as 9.8 A-hr\\/cu in. for aerospace secondary power. In flooded, negative limited cells electrodes made with a constant current step technique retained 80% of the

D. F. Pickett; V. Puglisi

1975-01-01

247

Electrolytic decontamination of surface-contaminated metal by alternating electrolysis using square-wave current in a neutral salt electrolyte  

SciTech Connect

Alternating square-wave current electrolysis using a Na2SO4 electrolyte was studied as a removal method for radioactive contaminated oxidation film on metal surfaces. After the oxidation film was selectively removed using the Na2SO4 electrolyte, base metal was removed. Based on a diffusion model in which the removal rate of the surface oxidation film depends on the diffusion rates of OS and FeS ions in the film, the optimum cycle of the alternating square current was estimated to be 90 s (the square widths of the negative and positive currents were 60 and 30 s, respectively). The theoretical estimation was in good agreement with the experiment results. Using this decontamination method, decontamination factors of 10T to 10U were obtained for stainless steels of a boiling water reactor coolant system and radioactive simulated samples.

Izumida, T.; Kato, K.; Kawamura, F.; Yusa, H.

1985-08-01

248

Cobalt hexaamine mediated electrocatalytic voltammetry of dimethyl sulfoxide reductase: driving force effects on catalysis.  

PubMed

The bacterial molybdoenzyme dimethyl sulfoxide (DMSO) reductase from Rhodobacter capsulatus catalyzes the reduction of DMSO to dimethyl sulfide in anaerobic respiration. In its native state, DMSO reductase is reduced to its active state by a pentaheme cytochrome (DorC). Alternatively, we show that DMSO reductase catalysis may be driven electrochemically using a series of homologous coordination compounds as mediating synthetic electron donors. All mediators are macrocyclic hexaaminecobalt(II) complexes in their active form, differing principally in their redox potentials over a range of about 250 mV. Thus, each complex presents a different reductive driving force to DMSO reductase and this leads to pronounced differences in the electrocatalytic behavior as measured by cyclic voltammetry. Digital simulation of the experimental voltammetry enables the critical features of the catalytic cycle to be extracted. PMID:20978811

Chen, Kuan-I; McEwan, Alastair G; Bernhardt, Paul V

2010-10-27

249

First-principles investigation of alternating current density distribution in molecular devices  

NASA Astrophysics Data System (ADS)

Using the nonequilibrium Green's function (NEGF) formalism, we derive the current density formula for ac quantum transport by including the self-consistent Coulomb interaction. It is well known that the Coulomb interaction is very important in determining ac current in nanostructures. As pointed out by Büttiker that the Coulomb interaction must be included to conserve the ac current. Theoretically, the displacement current can be accounted for by including a self-consistent Hartree term in the Hamiltonian as well as the exchange and correlation term while the ac current is calculated from particle current, i.e., <Î?(t)>=q where N?? is the number operator of the ? lead. For the ac current density, however, the Coulomb interaction contributes in two ways. As the case of ac current, the self-consistent Coulomb interaction has to be included in the conventional particle current density. In addition, we have to consider the displacement current density explicitly, which is proportional to the time derivative of displacement field. Once the ac current density is obtained, one can calculate the ac current by integrating it over a cross-section area along the transport direction. It is shown that ac current obtained from the total ac current density is conserved and equal to that calculated directly from the lead using NEGF theory. We have applied our formalism to calculate ac current density for nanodevices by combining the density functional theory (DFT) with NEGF theory. Specifically, we have calculated the ac current density to the first order of frequency in a molecular device Al-C4-Al from first principles. It is found that Al-C4-Al system exhibits inductive-like behavior under ac bias in the low-frequency limit. Furthermore, nonequilibrium charge distribution is obtained that enables us to study electrochemical capacitance of the molecular devices.

Zhang, Lei; Wang, Bin; Wang, Jian

2012-10-01

250

Non-local currents in 2D QFT: an alternative To the quantum inverse scattering method.  

National Technical Information Service (NTIS)

The formalism based on non-local charges that we propose provides an alternative to the quantum inverse scattering method for solving integrable quantum field theories in 2D. The content of the paper is: 1. Introduction: historical background. 2. The NLC ...

D. Bernard A. Leclair

1990-01-01

251

Current uses of laboratory animals in Japan and alternative methods in research, testing and education  

Microsoft Academic Search

Animals are used in biomedical research, toxicity testing and education. At least 8 million animals are used every year in Japan. More attention to and support of alternative methods characterized by the three `Rs' of reduction, refinement and replacement should be taken to reduce the number of animals used and to prevent unintended duplication in laboratory procedures. There are several

H Ninomiya; T Inomata

1998-01-01

252

Complementary and Alternative Medicine in Rural Communities: Current Research and Future Directions  

ERIC Educational Resources Information Center

|Contexts: The consumption of complementary and alternative medicine (CAM) in rural areas is a significant contemporary health care issue. An understanding of CAM use in rural health can provide a new perspective on health beliefs and practice as well as on some of the core service delivery issues facing rural health care generally. Purpose: This…

Wardle, Jon; Lui, Chi-Wai; Adams, Jon

2012-01-01

253

Wireless Architectural Alternatives: Current Economic Valuations versus Broadband Options, The Gilder Conjectures1  

Microsoft Academic Search

There has been an assumption that spectrum can be divided into segments and then auctioned off. It has been assumed that this is optimal in terms of its benefit to the public and that the FCC in so doing is optimizing the public good. There has been an alternative conjecture, termed the \\

Terrence P. McGarty; Muriel Medard

254

Noise investigation of the orthogonal fluxgate employing alternating direct current bias  

NASA Astrophysics Data System (ADS)

Alternating dc bias enables eliminating offset in orthogonal fluxgates operated in fundamental mode. However, the alternating dc bias reversals increase the fluxgate magnetic noise. It is shown in this work that the excess magnetic noise is related to the dynamics of the magnetic domains in the fluxgate core. The alternating dc bias reverses the fluxgate core magnetization causing nucleating domains and generating an intensive magnetic noise. To suppress the excess noise, two methods are suggested. The first method is based on eliminating the adequate parts of the fluxgate output appearing right after each dc bias reversal. The second method is based on introducing idle intervals between the dc bias reversals and subsequently eliminating the corresponding idle samples in the fluxgate output. Both methods suppress one and the same noise attributed to the domains relaxation dynamics and, hence, lead to similar results. In both cases, the fluxgate noise has been reduced down to its value in the excitation mode, where the dc bias is constant, and there are no reversals in the fluxgate core magnetization. The second method, however, has an advantage of lower power consumption due to the absence of both the ac and dc excitations during the idle intervals. Reducing the excess noise in the alternating dc bias mode, paves the way for developing a low-noise orthogonal fluxgates with practically no offset.

Weiss, Eyal; Paperno, Eugene

2011-04-01

255

Alternative solutions to the current situation of oocyte donation in Singapore  

Microsoft Academic Search

The rising incidence of age-related female infertility in Singapore, coupled with the prohibition on commercialized oocyte donation and egg sharing, has resulted in a severe shortage of donor oocytes. Infertile women are routinely encouraged by fertility doctors here to seek their close relatives and friends as prospective oocyte donors, which does not alleviate the shortage. A number of alternative solutions

Boon Chin Heng

2006-01-01

256

Wickedness of land amenagement: a critique of current land-management techniques and an inquiry into alternative approaches  

SciTech Connect

Land should be considered a non-renewable resource acknowledging that interests in landed property need to adjust accordingly. Given that some problems are wicked (they don't have definitive solutions and can only be repeatedly resolved) current planning models and the present political-economic construct within which land is utilized are considered insufficient. The wickedness of land issues leads to the concept of land amenagement, proposed instead of planning. Combining planning-action-management-stewardship, a set of design variables is developed to describe alternative amenagement approaches. Using this model, first some traditional approaches to land management are outlined: The multi-use policy of National Forests, agribusiness and regulation are examined and their difficulties analysed. Issues are derived from this analysis; these are proposed as a checklist of concerns to address in land-amenagement alternatives. Then some current, more-innovative approaches to land amenagement, such as land trusts and conservancies, are examined to resolve these issues. Possible directions for implementing new programs proposed within these alternatives are also discussed. Finally some alternatives which are yet to be implemented are described and examined in view of the issue checklist.

Luckey, D.

1981-01-01

257

Critical state solution and alternating current loss computation of polygonally arranged thin superconducting tapes  

NASA Astrophysics Data System (ADS)

The current density and field distributions in polygonally arranged thin superconducting tapes carrying AC current are derived under the assumption of the critical state model. Starting from the generic Biot-Savart law for a general polygonal geometry, we derive a suitable integral equation for the calculation of the current density and magnetic field in each tape. The model works for any transport current below Ic, which makes it attractive for studying cases of practical interest, particularly the dependence of AC losses on parameters such as the number of tapes, their distance from the center, and their separation.

Brambilla, Roberto; Grilli, Francesco; Martini, Luciano

2013-08-01

258

Higher Sensitivity Dopamine Measurements with Faster-Scan Cyclic Voltammetry  

PubMed Central

Fast-scan cyclic voltammetry with carbon-fiber microelectrodes has been successfully used to detect catecholamine release in vivo. Generally, waveforms with anodic voltage limits of 1.0 V or 1.3 V (vs. Ag/AgCl) are used for detection. The 1.0 V excursion provides good temporal resolution, but suffers from a lack of sensitivity. The 1.3 V excursion increases sensitivity, but also increases response time which can blur the detection of neurochemical events. Here, the scan rate was increased to improve the sensitivity of the 1.0 V excursion while maintaining the rapid temporal response. However, increasing scan rate increases both the desired faradaic current response and the already large charging current associated with the voltage sweep. Analog background subtraction was used to prevent the analog-to-digital converter from saturating from the high currents generated with increasing scan rate by neutralizing some of the charging current. In vitro results with the 1.0 V waveform showed approximately a four-fold increase in signal to noise ratio with maintenance of the desired faster response time by increasing scan rate up to 2400 V/s. In vivo, stable stimulated release was detected with an approximate four-fold increase in peak current. The scan rate of the 1.3 V waveform was also increased, but the signal was unstable with time in vitro and in vivo. Adapting the 1.3 V triangular wave into a sawhorse design prevented signal decay and increased the faradaic response. The use of the 1.3 V sawhorse waveform decreased the detection limit of dopamine with FSCV to 0.96 ± 0.08 nM in vitro and showed improved performance in vivo without affecting the neuronal environment. Electron microscopy showed dopamine sensitivity is in a quasi-steady state with carbon-fiber microelectrodes scanned to potentials above 1.0 V.

Keithley, Richard B.; Takmakov, Pavel; Bucher, Elizabeth S.; Belle, Anna M.; Owesson-White, Catarina A.; Park, Jinwoo; Wightman, R. Mark

2011-01-01

259

A new system for measuring alternating current magnetic susceptibility of natural materials over a wide range of frequencies  

Microsoft Academic Search

A new measurement system has been developed for detecting frequency dependence of low-field alternating current (AC) magnetic susceptibility in natural samples. Instead of employing intricate AC bridge circuits, this system configuration is simple and consists of a set of primary, secondary (pickup), and compensation coils; a function generator; and a two-phase lock-in amplifier. This system can measure both in-phase and

Kazuto Kodama

2010-01-01

260

A new type of arc plasma reactor with 12-phase alternating current discharge for synthesis of carbon nanotubes  

Microsoft Academic Search

A new type of arc plasma reactor with 12-phase alternating current (AC) discharge for synthesis of carbon nanotubes (CNTs) is proposed. A couple of six discharge electrodes by which have mutually electrical connection between them to enlarge the high-temperature regions in the reactor are arranged to three-dimensional locations. A new method of CNTs fabrication by this reactor, which accomplishes to

Tsugio Matsuura; Keiji Taniguchi; Takayuki Watanabe

2007-01-01

261

Investigation of the efficiency of pumping of fast-flow CO2 lasers by an alternating-current discharge  

Microsoft Academic Search

An experimental investigation was made of the efficiency of pumping of a fast-flow CO2 laser by an alternating-current discharge of 10-kHz frequency. A specific energy input of 200 J\\/g and a total vibrational efficiency of at least 50-60% were achieved in such a discharge. An analysis was made of the advantages of the proposed excitation method in various applications of

V. D. Gavriliuk; A. F. Glova; V. S. Golubev; F. V. Lebedev

1977-01-01

262

Measurement of excited Xe atoms density in alternating current plasma display panel by means of laser absorption spectroscopy  

Microsoft Academic Search

The exited Xe atoms in the 1s5 metastable state and the 1s4 resonance state across the two sustaining electrode have been monitored in a micro-discharge cell of alternating current plasma display panels (PDPs) by laser absorption spectroscopy. In this study, it is found that the maximum excited xenon density is 5.4×1012 cm-3 in the 1s5 metastable state and 1.2×1012 cm-3

Phil Yong Oh; Jun Ho Lee; Se Hoon Jeong; Han Seb Moon; Soo Beom Lee; Ki Baek Song; Yoon Jung; Yunki Kim; Gaungsup Cho; Han S. Uhm; Eun Ha Choi

2006-01-01

263

Vacuum ultraviolet emission characteristics from He–Ne–Xe gas discharge in an alternating current plasma display panel cell  

Microsoft Academic Search

We measured the time integrated vacuum ultraviolet (VUV) emission spectra of He–Ne–Xe gas mixture from a surface type alternating current (ac) plasma display panel cell. The measured emission lines are the resonance line (147 nm) from Xe*(1s4), the first continuum (150 nm) and the second continuum (173 nm) from Xe dimer excited states. The relative intensities of VUV spectral lines

Jeong Hyun Seo; Heui Seob Jeong; Joo Yul Lee; Cha Keun Yoon; Joong Kyun Kim; Ki-Woong Whang

2000-01-01

264

A new laser direct etching method of indium tin oxide electrode for application to alternative current plasma display panel  

Microsoft Academic Search

For cost effective fabrication and time of alternative current plasma display panels (AC PDPs), an indium tin oxide (ITO) layer was patterned directly with a Q-switched diode pumped Nd:YVO4 laser (?=1064nm). As experimental results, 500mm\\/s scan speed with 40kHz repetition rate was suitable for the application to AC PDP ITO electrode. In comparison with the chemically wet-etched ITO patterns by

Zhao Hui Li; Eou Sik Cho; Sang Jik Kwon

2009-01-01

265

Influence of wall-charge accumulation on the gas dielectric barrier discharge in alternating current plasma display panel  

Microsoft Academic Search

Influences of wall-charge accumulation on gas dielectric barrier discharge (DBD) breakdown threshold and sustaining voltage margin of alternating current plasma display panel (AC-PDP) were investigated. It is observed that wall-charge accumulation results in a remarkable increase of gas DBD breakdown threshold during sustaining discharge period. Sustaining voltage margin is reduced by the threshold increase. A larger margin can be obtained

Bingang Guo; Wei Wei; Tsutae Shinoda; Chunliang Liu

2007-01-01

266

Relationship between the microstructure and the discharge characteristics of MgO protecting layer in alternating current plasma display panels  

Microsoft Academic Search

MgO thin films, which are generally deposited by e-beam evaporation, are widely used as a protecting layer on the dielectric layer of alternating current plasma display panels (AC-PDPs). Its properties are quite sensitive to the evaporation and post-treatment conditions. However, the key factors affecting the discharge characteristics are not well known. This study examines the relationship between the microstructure of

Sun Young Park; Mi Jung Lee; Hyeong Joon Kim; Sung Hwan Moon; Soo Gil Kim; Jong Kuk Kim

2005-01-01

267

Vacuum ultraviolet emission characteristics from He-Ne-Xe gas discharge in an alternating current plasma display panel cell  

Microsoft Academic Search

We measured the time integrated vacuum ultraviolet (VUV) emission spectra of He-Ne-Xe gas mixture from a surface type alternating current (ac) plasma display panel cell. The measured emission lines are the resonance line (147 nm) from Xe*(1s4), the first continuum (150 nm) and the second continuum (173 nm) from Xe dimer excited states. The relative intensities of VUV spectral lines

Jeong Hyun Seo; Heui Seob Jeong; Joo Yul Lee; Cha Keun Yoon; Joong Kyun Kim; Ki-Woong Whang

2000-01-01

268

Bacteria capture, concentration and detection by alternating current dielectrophoresis and self-assembly of dispersed single-wall carbon nanotubes  

Microsoft Academic Search

The high polarizability and dielectrophoretic mobility of single-walled carbon nano- tubes (SWNT) are utilized to capture and detect low numbers of bacteria and sub- micron particles in milliliter-sized samples. Concentrated SWNT solutions are mixed with the sample and a high-frequency (.100 kHz) alternating current (AC) field is applied by a microelectrode array to enhance bulk absorption of the particles (bacteria

Ronghui Zhou; Ping Wang; Hsueh-Chia Chang

2006-01-01

269

Model-based characterization of homogeneous metal plates by four-point alternating current potential drop measurements  

Microsoft Academic Search

We determined the conductivity, relative permeability, and thickness of homogeneous metal plates from four-point measurements of alternating current potential drop (ACPD) over the frequency range 1 Hz to 10 kHz. We developed simple analytical expressions from which these parameters can be calculated. In the low-frequency regime, in which the measured voltage tends to a constant, real value, the relative permeability

Nicola Bowler; Yongqiang Huang

2005-01-01

270

Stepwise behavior of the core trajectory in magnetic vortex dynamics under an alternating-current magnetic field  

NASA Astrophysics Data System (ADS)

We predict that the radial distance of a magnetic vortex core from the disk center shows a stepwise behavior during initial excited motion under an alternating-current magnetic field by means of micromagnetic simulations. The stepwise behavior is clearly observed around the resonance frequency and depends on the amplitude and frequency of the external magnetic field. It has been found that the stepwise behavior originates from the relative phase difference between the gyrovector and the radial distance of the vortex core.

Shim, Je-Ho; Piao, Hong-Guang; Hyuk Lee, Sang; Kun Oh, Suhk; Yu, Seong-Cho; Kee Han, Seung; Eon Kim, Dong; Kim, Dong-Hyun

2013-05-01

271

Field-Filter Probes and the Measurement of Alternating-Current Corona  

Microsoft Academic Search

The principles of the field-filter probe, which is capable of measuring both field changes and conduction current at an electrode in the presence of space charge, are described. Design characteristics are given for a simple field filter and for two further types which can be used for bipolar (reversing) fields and currents. Measurements are given for the discharge characteristics at

W. Brian Stark; Elsayed O. Selim; Ronald T. Waters

1980-01-01

272

Differentiating fiber optic Mach-Zehnder interferometer for alternating current measurements  

Microsoft Academic Search

A multiplexed Mach-Zehnder interferometer is proposed for measuring time varying signals. The system was implemented to measure electrical currents. These measurements are facilitated by a current transformer terminated with a resistive load, which derives a piezoelectric phase modulator. Frequency domain demultiplexing allows interrogation of the sensors in each of the conductors of a three-phase electrical system. Different phase modulating carriers

Pieter L. Swart; Stephanus J. Spammer; David C. Theron

1996-01-01

273

A survey of current worldwide research on the thermophysical properties of alternative refrigerants  

Microsoft Academic Search

The survey represents an exhaustive compilation of the research activities throughout the world concerned with either measurements or correlations of the thermophysical properties of alternative refrigerants. The properties covered include thermodynamic, transport, phase equilibria, and other properties such as dielectric constant and refractive index. The survey included a wide range of fluids (including R23, R32, R125, R143a, R22, R134a, R152a,

M. O. McLinden; W. M. Haynes; J. T. R. Watson; K. Watanabe

1991-01-01

274

Effects of alternating magnetic fields and low-frequency electric currents on human skin blood flow  

Microsoft Academic Search

The influence of alternating magnetic fields on human skin blood flow was investigated. The hands of volunteers were fixed\\u000a just above an induction heater and the regional skin blood flow of a fingertip was measured by a laser Doppler flowmeter.\\u000a The hands were exposed to fields with flux densities of 16 mT, 32 mT and 48 mT at a frequency

S. Ueno; P. Lövsund; P. Å. Öberg

1986-01-01

275

A current opinion on electrophoretic deposition in pulsed and alternating fields.  

PubMed

Electrophoretic deposition (EPD) is a colloidal production process developed in the early 20th century. Industrial scale EPD for the production of electronic components and phosphorescent screens and in the form of cataphoretic painting has known some success. Despite its limited practical applications, the inherent versatility of EPD has never ceased to fuel research into this technique. One of the major drives of this research was to render the method more environmentally friendly by enabling deposition from aqueous suspensions. One particular route, suggested to circumvent the problems caused by the use of water in EPD, is the use of alternating or pulsed fields. Recently, the use of alternating fields in EPD has been investigated for the deposition of biological matter in the form of cells and molecules. With this new avenue of research opening up and coinciding with a rise in biotechnological processes, one can expect a renewed interest in traditional EPD and fundamental research on the use of pulsed and alternating fields in this technique. Hence, this review attempts to summarize a century's worth of both fundamental and applied research for scientists venturing into the field of EPD. PMID:22998240

Neirinck, Bram; Van der Biest, Omer; Vleugels, Jef

2012-10-02

276

Cyclic Voltammetry of Polysulfide (Thiokol) Prepolymers and Related Compounds.  

National Technical Information Service (NTIS)

The cyclic voltammetry of polysulfide prepolymers and related monomeric sulfur compounds was examined at a gold wire electrode. Electrode processes were assigned to the polysulfide prepolymers on the basis of those occurring in the model compounds. It was...

W. Mazurek

1983-01-01

277

46 CFR 111.05-27 - Grounded neutral alternating current systems.  

Code of Federal Regulations, 2012 CFR

...fault current without damage, and provides continuous indication of circuit status to ground. A provision must be included to compare indications under fault conditions with those under normal conditions. [CGD 94-108, 62 FR 23907, May 1,...

2012-10-01

278

Electromagnetic form factors of the ? and ? baryons in an alternative baryonic current approach  

NASA Astrophysics Data System (ADS)

Light-cone sum rules are used to investigate the electromagnetic form factors of the ? and ? baryons by using the Ioffe-type interpolating currents. The sum rules are affected to some extent by the choice of the interpolating currents from a comparison. Numerical calculations show that the magnetic form factor can be well fitted by the dipole formula for ? but not for ?. The magnetic form factor of ? approaches zero with the momentum transfer faster than the dipole formula estimation.

Liu, Yong-Lu; Huang, Ming-Qiu

2009-06-01

279

Current alternative energy research and development in Illinois, December 1988. Annual report  

SciTech Connect

This Directory is intended to acquaint researchers, policy makers and citizens with recent activities in alternative energy research, development and demonstration projects. The topics covered were limited to those concerned with the development of non-fossil, non-nuclear energy sources. Included are projects in process in October 1988 or that have been completed after December 1987. It attempts to include projects performed by Illinois organizations, both within the state and out-of-state, and projects performed by out-of-state organizations at sites within Illinois.

Swager, R.

1989-05-01

280

Electrochemical production of ferrate(VI) using sinusoidal alternating current superimposed on direct current: grey and white cast iron electrodesThis paper is dedicated to the memory of Professor Ivo Roušar  

Microsoft Academic Search

The current yield during the electrochemical production of ferrate(VI) in a batch cell was measured using grey and white cast iron as working electrode materials. Sinusoidal alternating current superimposed on the direct current with a frequency varying in the range 0.1mHz to 5kHz was used. The amplitude (peak to peak) of the alternating current component varied from 39.8 to 91.1mAcm?2

K Bouzek; M Lipovská; M Schmidt; I RoušarDeceased; A. A Wragg

1998-01-01

281

Current and future alternatives to warfarin for the prevention of stroke in atrial fibrillation.  

PubMed

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice and is associated with a nearly 5-fold increase in the risk of stroke. Warfarin has been the cornerstone of treatment to reduce stroke risk in AF patients for decades. Although effective in preventing thrombosis, warfarin is difficult to manage and is associated with a 1% to 7% yearly risk of major hemorrhage. Until recently, there were no effective oral alternatives to warfarin. Dabigatran etexilate, a direct thrombin inhibitor, was approved in 2010 for the reduction of stroke and systemic embolism in patients with nonvalvular AF, and the factor Xa inhibitor rivaroxaban was approved for a similar indication in 2011. Other late-stage orally administered agents that may be approved for this indication include apixaban and edoxaban; others at earlier stages of development will be discussed in this review as well. Nonpharmacological approaches to stroke prevention include left atrial appendage removal, ligation, or occlusion. This review examines advances in the management of stroke risk in AF patients, focusing on recently marketed and late-stage modalities. The advent of alternatives to warfarin for reducing stroke risk in AF patients may improve physicians' ability to offer safe and effective stroke prevention in all AF patients. PMID:22595814

Bommer, William J

2012-06-01

282

Human norepinephrine transporter kinetics using rotating disk electrode voltammetry.  

PubMed

Rotating disk electrode (RDE) voltammetry is applied to the measurement of the transport of the catecholamine neurotransmitters norepinephrine (4-(2-amino-1-hydroxyethyl)-1,2-benzenediol, NE) and dopamine (3,4-dihydroxyphenethylamine, DA) in suspensions of LLC-NET cells, a line of porcine kidney cells expressing the human norepinephrine transporter (hNET). Initial rate of transport was assessed by following the initial decrease in neurotransmitter after its addition to the cell suspension, as measured by the decrease in oxidation current at +0.45 V vs Ag/AgCl. The initial rate of norepinephrine uptake was saturable, with Vmax and KM of 197 +/- 17 amol min-1 cell-1 and 1.64 +/- 0.46 microM, respectively. The RDE method also allows observation of outward transport (efflux) of the DA or NE previously taken up by the cells. Outward transport was induced by the addition of either d-amphetamine (d-AMPH) or p-tyramine (4-hydroxyphenethylamine, p-TYR), which are also substrates for the NE transporter. The technique was also used to monitor accelerated NE uptake by cells preloaded with p-TYR, a phenomenon distinguishing carriers from channels. Together, these findings document the utility of RDE for the nonisotopic measurement of neurotransmitter influx and efflux from transfected mammalian cells. PMID:8794928

Burnette, W B; Bailey, M D; Kukoyi, S; Blakely, R D; Trowbridge, C G; Justice, J B

1996-09-01

283

A Current Update on the Rule of Alternative and Complementary Medicine in the Treatment of Liver Diseases  

PubMed Central

There is a vast body of knowledge which is ever-increasing about the treatment of liver disease with alternative and complementary medicine for which hundreds of thousands of literatures have been documented. Liver disease is a general term. This term covers all the potential problems that cause the liver to fail to perform its specified operations. Liver disease has a variety of presentations and causes a great public health problem worldwide which threatens the wellness of billions of people. Incidences of many types of liver disease are currently rising. Although there is still a debate about the entity of alternative and complementary medicine, it is now widely used and it is improving. And it covers the shortages and compensates for the weaknesses of conventional methods in the treatment of liver diseases. Alternative and complementary medicine for liver diseases provides benefits by regulating immunity, controlling disease progression, improving quality of life, and prolonging survival. This paper reviews the increasing interest and growing research into alternative and complementary medicine for liver diseases, with a look at the rough classification, principle of management, evidence-based applications, and issues for prescription and perspectives.

Guan, Yong-Song; He, Qing

2013-01-01

284

Assessing the Liquidity of Firms: Robust Neural Network Regression as an Alternative to the Current Ratio  

NASA Astrophysics Data System (ADS)

Artificial neural networks have proven to be useful tools for solving financial analysis problems such as financial distress prediction and audit risk assessment. In this paper we focus on the performance of robust (least absolute deviation-based) neural networks on measuring liquidity of firms. The problem of learning the bivariate relationship between the components (namely, current liabilities and current assets) of the so-called current ratio is analyzed, and the predictive performance of several modelling paradigms (namely, linear and log-linear regressions, classical ratios and neural networks) is compared. An empirical analysis is conducted on a representative data base from the Spanish economy. Results indicate that classical ratio models are largely inadequate as a realistic description of the studied relationship, especially when used for predictive purposes. In a number of cases, especially when the analyzed firms are microenterprises, the linear specification is improved by considering the flexible non-linear structures provided by neural networks.

de Andrés, Javier; Landajo, Manuel; Lorca, Pedro; Labra, Jose; Ordóñez, Patricia

285

Determination of heavy metals by thin-layer chromatography-square-wave anodic stripping voltammetry  

SciTech Connect

A square-wave anodic stripping voltammetric method is described for low parts per million determination of heavy metals separated by thin-layer chromatography (TLC). Heavy metal samples are separated on carboxymethyl cellulose TLC plates and detected by anodic stripping voltammetry (ASV) using a cellulose dialysis membrane-covered mercury film electrode (CM-MFE) placed directly on the TLC plate surface in a thin film of supporting electrolyte solution. The fast scan rates possible in square-wave voltammetry during the stripping step eliminate the need to deoxygenate the sample. Results are presented for a mixture of Pb(II), Cd(II), Cu(II), and Zn(II). Calibration curves for Pb(II) were linear over the range 10-500 ng, with a relative standard deviation of the peak current over a set of eight separate 100-ng Pb(II) samples of 16%. 25 refs., 7 figs.

Aldstadt, J.H.; Dewald, H.D. (Ohio Univ., Athens (United States))

1992-12-15

286

A survey of current worldwide research on the thermophysical properties of alternative refrigerants  

NASA Astrophysics Data System (ADS)

The survey represents an exhaustive compilation of the research activities throughout the world concerned with either measurements or correlations of the thermophysical properties of alternative refrigerants. The properties covered include thermodynamic, transport, phase equilibria, and other properties such as dielectric constant and refractive index. The survey included a wide range of fluids (including R23, R32, R125, R143a, R22, R134a, R152a, R134, R124, R142b, R123, R123a, R141b) along with mixtures containing at least one of these fluids. Summary information is presented in tabular form about each research activity; the survey does not present raw data or correlating equations.

McLinden, M. O.; Haynes, W. M.; Watson, J. T. R.; Watanabe, K.

1991-06-01

287

Variable Uses of Alternative Conceptions: A Case Study in Current Electricity  

NSDL National Science Digital Library

Fourteen elementary and middle school teachers from an inservice physics course were found to share a common core of strongly held propositions that formed a coherent, but incorrect and contradictory, model of the sequential flow of electrical current. Theoretical and practical implications of these teachers' beliefs with respect to both instructional techniques and curriculum design are discussed. (17 references)

Heller, Patricia; Finley, Fred

2006-06-22

288

Multibeam waveguide CO2 laser excited by an alternating-current discharge  

Microsoft Academic Search

The development is reported of a multibeam laser, excited by an ac discharge in the frequency range ~10-70 kHz. The results are given of an investigation of the active medium and of the dependence of the output characteristics of such lasers on the discharge tube diameter, pressure in the gas mixture, and frequency of the pump current.

V. V. Antyukhov; A. F. Glova; O. R. Kachurin; F. V. Lebedev

1980-01-01

289

Multibeam waveguide CO2 laser excited by an alternating-current discharge  

Microsoft Academic Search

We report the development of a multibeam laser, excited by an ac discharge in the frequency range approximately 10 to 70 kHz. The results are given of an investigation of the active medium and of the dependence of the output characteristics of such lasers on the discharge tube diameter, pressure in the gas mixture, and frequency of the pumping current.

V. V. Antyukhov; Alexander F. Glova; O. R. Kachurin; Fedor V. Lebedev

1993-01-01

290

Formula Apportionment: Is it better than the current system and are there better alternatives?  

Microsoft Academic Search

This analysis of formula apportionment compared to the current system is based on the observation that income shifting has two sources, intangible income and debt. The analysis also recognizes that a major goal of the transfer pricing or income allocation system is to preserve the tax neutrality between arm’s length and related party transactions and between multinational and single jurisdiction

Rosanne Altshuler; Harry Grubert

2009-01-01

291

Neutral currents and weak boson masses in alternative electroweak gauge theories  

SciTech Connect

A natural SU(2) x U(1) x SU(2)' electroweak gauge model is constructed with fermions that transform according to SU(2) x U(1) in the usual way. The predictions for neutral-current interactions at low energies are essentially the same as for the standard model. Using current measurements of the reaction e/sup +/e/sup -/ ..-->.. ..mu../sup +/..mu../sup -/ upper limits of 86 and 105 GeV are placed on the lightest W and Z masses, respectively. A hierarchy of Higgs boson vacuum expectation values could explain small fermion masses and yield gauge boson masses above their standard model values. High energy predictions of the model are explored. The model is extended to U(1) x SU(2)/sup N/. The most general two-Z electroweak gauge model with two weak neutral currents and no anomalies is discussed. The effective neutral-current interaction at low energies is specified by five parameters. These parameters are determined from a fit to data for the special case of left-right models, with and without constraints from Higgs structure. From this phenomenological analysis, the neutral-boson masses in left-right models are found to be constrained to the intervals 78 < M/sub Z/sub 1// < 111 GeV and M/sub Z/sub 2// > 195 GeV, before radiative corrections to the mass. Mass limits are also discussed for the general case. The natural two-Z model and an SU(2) x U(1) x U(1) model with identical hypercharge currents and unbounded Z masses are shown to be limiting cases of the general formalism. General constraints on neutral-current couplings in left-right models which result from the breakdown of an SO(10) grand unified model are derived. The contributions of Higgs bosons to the renormalization group equations and the bound from the experimental limit on proton decay are included. The resulting limits are combined with the phenomenological analysis of left-right models to obtain gauge boson mass bounds and limits on the symmetry-breaking scales.

Whisnant, K.L.

1982-01-01

292

Reaction Mechanism and Improved Performance of Solution-Based Electrochemiluminescence Cell Driven by Alternating Current  

NASA Astrophysics Data System (ADS)

An AC-driven light-emitting cell based on the electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)32+] was fabricated by simply placing the electrolyte solution between transparent electrodes, and this AC-driven ECL cell was demonstrated for comparison to a DC-ECL cell. The properties of the ECL cell were dramatically improved by using the AC method. The AC-ECL cell showed the luminance of 56.4 cd/m2, the current efficiency of 0.78 cd/A and the turn-on response time of ca. 15 ms under application of 4 V, 50 Hz AC. We also elucidated the detailed mechanisms of the AC-ECL reaction to monitor the faradaic current. These improved properties and the frequency dependence of the AC-ECL cell were discussed in the relation to the revealed mechanisms.

Nobeshima, Taiki; Nakamura, Kazuki; Kobayashi, Norihisa

2013-05-01

293

Analysis of current and alternative phenol based RNA extraction methodologies for cyanobacteria  

PubMed Central

Background The validity and reproducibility of gene expression studies depend on the quality of extracted RNA and the degree of genomic DNA contamination. Cyanobacteria are gram-negative prokaryotes that synthesize chlorophyll a and carry out photosynthetic water oxidation. These organisms possess an extended array of secondary metabolites that impair cell lysis, presenting particular challenges when it comes to nucleic acid isolation. Therefore, we used the NHM5 strain of Nostoc punctiforme ATCC 29133 to compare and improve existing phenol based chemistry and procedures for RNA extraction. Results With this work we identify and explore strategies for improved and lower cost high quality RNA isolation from cyanobacteria. All the methods studied are suitable for RNA isolation and its use for downstream applications. We analyse different Trizol based protocols, introduce procedural changes and describe an alternative RNA extraction solution. Conclusion It was possible to improve purity of isolated RNA by modifying protocol procedures. Further improvements, both in RNA purity and experimental cost, were achieved by using a new extraction solution, PGTX.

Pinto, Fernando Lopes; Thapper, Anders; Sontheim, Wolfgang; Lindblad, Peter

2009-01-01

294

Effects of Surface and Plate-Gap Discharges on Panel-Aging Characteristics in Alternating-Current Plasma Display Panel  

NASA Astrophysics Data System (ADS)

In this study, we investigate the changes in surface morphology of the MgO layer on both the bus and indium tin oxide (ITO) electrodes in an alternating-current (AC) plasma display panel (PDP) under the surface and plate-gap discharges during the panel-aging process. It is found that the use of the surface discharge mixed with the plate-gap discharge during the panel-aging process contributes to obtaining uniform MgO surface morphologies for both bus and ITO electrodes within a fast panel-aging process time.

Park, Choon-Sang; Tae, Heung-Sik

2012-09-01

295

Influence of wall-charge accumulation on the gas dielectric barrier discharge in alternating current plasma display panel  

SciTech Connect

Influences of wall-charge accumulation on gas dielectric barrier discharge (DBD) breakdown threshold and sustaining voltage margin of alternating current plasma display panel (AC-PDP) were investigated. It is observed that wall-charge accumulation results in a remarkable increase of gas DBD breakdown threshold during sustaining discharge period. Sustaining voltage margin is reduced by the threshold increase. A larger margin can be obtained when the threshold is decreased by removing unfavorable influence of wall-charge accumulation. Compared with normal margin, improved margin has a larger value and a faster linear increase with increasing wall-charge voltage. That indicates a way to improve AC-PDP performances remarkably.

Guo Bingang; Wei Wei; Shinoda, Tsutae; Liu Chunliang [Advanced Display Research Center, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba Meguro-Ku, Tokyo 153-8505 (Japan); Key Laboratory for Physical Electronics and Devices of the Ministry of Education of China, Xi'an Jiaotong University, Xi'an, Shaanxi Province, 710049 (China)

2007-03-05

296

Mixing enhancement by biologically inspired convection in a micro-chamber using alternating current galvanotactic control of the Tetrahymena pyriformis  

NASA Astrophysics Data System (ADS)

Recently, there has been increasing interest in the swimming behavior of microorganisms and biologically inspired micro-robots. In this study, we investigated biologically induced convection flow with living microorganism using galvanotaxis. We fabricated and evaluated our micro-mixer with motile cells. For the cell based active micro-mixers, two miscible fluids were used to measure the mixing index. Under alternating current (AC) electric fields with varying frequency, a group of motile Tetrahymena pyriformis cells generated reciprocal motion with circulating flows around their pathline, enhancing the mixing ratio.

Kim, Jihoon; Jang, Yonghee; Byun, Doyoung; Hyung Kim, Dal; Jun Kim, Min

2013-09-01

297

Study of corrosion of super martensitic stainless steel under alternating current in artificial seawater with electrochemical impedance spectroscopy  

SciTech Connect

The assessment of corrosion requires the use of tools able to quantify the corrosion but often times also qualify it. Electrochemical Impedance Spectroscopy (EIS) is a laboratory tool that can provide both qualification and quantification of corrosion. EIS was successfully used to compare the thickness of the corrosion products formed during the application of different alternating current (AC) densities as well as to characterize pitting. When EIS is applied at the open circuit potential, the technique is nondestructive and predicts the corrosion behavior of the electrode. It can also be used at cathodic potentials while still being nondestructive, providing information about the electrode reaction kinetics, diffusion and electrical double layer.

Reyes, T.; Bhola, S.; Olson, D. L.; Mishra, B. [Colorado School of Mines, Golden CO 80401 (United States)

2011-06-23

298

On the Separation of Half-Wave Potentials Required for Resolution of Simple, Reversible, Overlapping Waves in Stationary Electrode Voltammetry  

Microsoft Academic Search

Linear potential sweep voltammetry at stationary or quasi-stationary electrodes has become a widely accepted analytical technique. In contrast with the well-known dc polarographic current-voltage curve which reaches a limiting current (i) at potentials sufficiently removed from the half-wave potential (E), the voltammetric curve at a stationary electrode in unstirred solution reaches a maximum value (i) after which the current decreases

T. R. Mueller

1968-01-01

299

Analysis of operations and cyber security policies for a system of cooperating Flexible Alternating Current Transmission System (FACTS) devices.  

SciTech Connect

Flexible Alternating Current Transmission Systems (FACTS) devices are installed on electric power transmission lines to stabilize and regulate power flow. Power lines protected by FACTS devices can increase power flow and better respond to contingencies. The University of Missouri Rolla (UMR) is currently working on a multi-year project to examine the potential use of multiple FACTS devices distributed over a large power system region in a cooperative arrangement in which the FACTS devices work together to optimize and stabilize the regional power system. The report describes operational and security challenges that need to be addressed to employ FACTS devices in this way and recommends references, processes, technologies, and policies to address these challenges.

Phillips, Laurence R.; Tejani, Bankim; Margulies, Jonathan; Hills, Jason L.; Richardson, Bryan T.; Baca, Micheal J.; Weiland, Laura

2005-12-01

300

The effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels  

NASA Astrophysics Data System (ADS)

In this work, we studied the effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels. Through discharge current analysis, we observed that self-erase discharge occurred mainly between the sustain cathode and the address electrode, which has an influence on the luminous efficacy. We varied the amount and timing of the self-erase discharge in order to observe the effects on the luminous efficacy. We found that the luminous efficacy could be improved by a self-erase discharge when adjusted to occur right before the main discharge in the small gap structure. In the long gap structure, on the contrary, we could increase the luminous efficacy when we suppressed the self-erase discharge. In addition, we suggest various waveforms to control self-erase discharge as a result of our panel experiments.

Kim, Tae Jun; Kim, Joong Kyun; Jung, Jae-Chul; Jung, Hae-Yoon; Whang, Ki-Woong

2009-07-01

301

Enhancement of Non-Equilibrium Atmospheric Pressure He Plasma Discharges by Using Silicon Diode for Alternating Current  

NASA Astrophysics Data System (ADS)

In this paper, we report that enhanced He dielectric barrier discharges (DBDs) using simple and inexpensive device, such as Silicon Diode for Alternating Current (SIDAC) and high voltage transformer at commercial frequency. The SIDAC is designed for direct interface with the ac power line as fast switching and pulse devices. Here, discharge characteristics of He DBDs using SIDACs connected in series are studied experimentally. It can be obtained by using 15 series SIDACs that a rapid voltage change at the SIDAC breakover is dv/dt ~20 kV/?sec and the pulsed DBD current with a duration of ~200 nsec reaches ~1 A, 100 times larger than that of the normal DBD without SIDACs. Emission intensity of He DBD is also increased strongly by series SIDACs to be ~100 times larger compared without the SIDACs.

Sumiishi, Yujiro; Uesugi, Yoshihiko; Tanaka, Yasunori; Ishijima, Tatsuo

2013-06-01

302

Influence of Nitrogen Addition on Fundamental Discharge Properties in Alternating Current Plasma Display Panels  

NASA Astrophysics Data System (ADS)

In order to clarify the influence of nitrogen addition on the fundamental properties of plasma display panel (PDP) discharges in Ne/Xe(10%) gas mixture, the PDP discharges in Ne/Xe/N2 gas mixtures have been simulated using an one-dimensional fluid model, based on the continuity equations for electrons, ions, excited atoms and molecules, the Poisson equation and the electron energy balance equation. From simulation results, it is found that pulsed discharge with a short time (?100 ns) occurs once during every half cycle. In case of nitrogen concentration more than 100 ppm, the phase-delay of the gap-voltage and discharge current in Ne/Xe gas mixture PDP discharges began to appear.

Oda, Akinori; Hirano, Yoshikuni

303

Including Alternative Resources in State Renewable Portfolio Standards: Current Design and Implementation Experience  

SciTech Connect

Currently, 29 states, the District of Columbia, and Puerto Rico have instituted a renewable portfolio standard (RPS). An RPS sets a minimum threshold for how much renewable energy must be generated in a given year. Each state policy is unique, varying in percentage targets, timetables, and eligible resources. This paper examines state experience with implementing renewable portfolio standards that include energy efficiency, thermal resources, and non-renewable energy and explores compliance experience, costs, and how states evaluate, measure, and verify energy efficiency and convert thermal energy. It aims to gain insights from the experience of states for possible federal clean energy policy as well as to share experience and lessons for state RPS implementation.

Heeter, J.; Bird, L.

2012-11-01

304

Effects of weak transcranial alternating current stimulation on brain activity--a review of known mechanisms from animal studies  

PubMed Central

Rhythmic neuronal activity is ubiquitous in the human brain. These rhythms originate from a variety of different network mechanisms, which give rise to a wide-ranging spectrum of oscillation frequencies. In the last few years an increasing number of clinical research studies have explored transcranial alternating current stimulation (tACS) with weak current as a tool for affecting brain function. The premise of these interventions is that tACS will interact with ongoing brain oscillations. However, the exact mechanisms by which weak currents could affect neuronal oscillations at different frequency bands are not well known and this, in turn, limits the rational optimization of human experiments. Here we review the available in vitro and in vivo animal studies that attempt to provide mechanistic explanations. The findings can be summarized into a few generic principles, such as periodic modulation of excitability, shifts in spike timing, modulation of firing rate, and shifts in the balance of excitation and inhibition. These effects result from weak but simultaneous polarization of a large number of neurons. Whether this can lead to an entrainment or a modulation of brain oscillations, or whether AC currents have no effect at all, depends entirely on the specific dynamic that gives rise to the different brain rhythms, as discussed here for slow wave oscillations (?1 Hz) and gamma oscillations (?30 Hz). We conclude with suggestions for further experiments to investigate the role of AC stimulation for other physiologically relevant brain rhythms.

Reato, Davide; Rahman, Asif; Bikson, Marom; Parra, Lucas C.

2013-01-01

305

Optimizing the Temporal Resolution of Fast-Scan Cyclic Voltammetry  

PubMed Central

Electrochemical detection with carbon-fiber microelectrodes has become an established method to monitor directly the release of dopamine from neurons and its uptake by the dopamine transporter. With constant potential amperometry (CPA), the measured current provides a real time view of the rapid concentration changes, but the method lacks chemical identification of the monitored species and markedly increases the difficulty of signal calibration. Monitoring with fast-scan cyclic voltammetry (FSCV) allows species identification and concentration measurements but often exhibits a delayed response time due to the time-dependent adsorption/desorption of electroactive species at the electrode. We sought to improve the temporal resolution of FSCV to make it more comparable to CPA by increasing the waveform repetition rate from 10 to 60 Hz with uncoated carbon-fiber electrodes. The faster acquisition led to diminished time delays of the recordings that tracked more closely with CPA measurements. The measurements reveal that FSCV at 10 Hz underestimates the normal rate of dopamine uptake by about 18%. However, FSCV collection at 10 and 60 Hz provide identical results when a dopamine transporter (DAT) blocker such as cocaine is bath applied. To verify further the utility of this method, we used transgenic mice that overexpress DAT. After accounting for the slight adsorption delay time, FSCV at 60 Hz adequately monitored the increased uptake rate that arose from overexpression of DAT and, again, was similar to CPA results. Furthermore, the utility of collecting data at 60 Hz was verified in an anesthetized rat by using a higher scan rate (2400 V/s) to increase sensitivity and the overall signal.

2012-01-01

306

Analytical expressions for proton transfer voltammetry: analogy to surface redox voltammetry with Frumkin interactions.  

PubMed

Theory for interfacial proton transfer voltammetry of a molecular film containing any acid/base loading has been developed under equilibrium conditions. Diagnostic criteria to disentangle the interplay between diffuse layer and ionization effects are outlined. Easy-to-use analytical expressions for the voltammetric features are derived for the particular case of an invariant diffuse layer effect, which turn out to be entirely analogous to those for a surface redox conversion with Frumkin interactions. It is demonstrated that, regardless of the electrolyte concentration, significant ionization of the external acid groups located nearby the diffuse layer is sufficient for the fulfillment of this relevant particular case. A strategy is outlined to determine the amount, the intrinsic pKa, and the burial depth of the voltammetrically active groups from the surface concentration dependence of the main voltammetric features. Self-assembled monolayers of 11-mercaptoundecanoic acid deposited on Au(111), containing higher amounts of buried carboxylic groups than previously reported, have been studied to assess more critically the influence of electrostatic effects on the ionization process. Preliminary evidence suggests that the protonation/deprotonation voltammetric wave involves physisorbed rather than chemisorbed thiol molecules. Application of the present theoretical approach to this system reveals that the voltammetrically active carboxylic groups are located close to the electrode surface and become more acidic upon increasing their surface concentration. PMID:23534339

Calvente, Juan José; Luque, Antonio M; Andreu, Rafael; Mulder, Willem H; Olloqui-Sariego, José Luis

2013-04-16

307

Calorimetric AC loss measurement of MgB2 superconducting tape in an alternating transport current and direct magnetic field  

NASA Astrophysics Data System (ADS)

Applications of MgB2 superconductors in electrical engineering have been widely reported, and various studies have been made to define their alternating current (AC) losses. However, studies on the transport losses with an applied transverse DC magnetic field have not been conducted, even though this is one of the favored conditions in applications of practical MgB2 tapes. Methods and techniques used to characterize and measure these losses have so far been grouped into ‘electrical’ and ‘calorimetric’ approaches with external conditions set to resemble the application conditions. In this paper, we present a new approach to mounting the sample and employ the calorimetric method to accurately determine the losses in the concurrent application of AC transport current and DC magnetic fields that are likely to be experienced in practical devices such as generators and motors. This technique provides great simplification compared to the pickup coil and lock-in amplifier methods and is applied to a long length (˜10 cm) superconducting tape. The AC loss data at 20 and 30 K will be presented in an applied transport current of 50 Hz under external DC magnetic fields. The results are found to be higher than the theoretical predictions because of the metallic fraction of the tape that contributes quite significantly to the total losses. The data, however, will allow minimization of losses in practical MgB2 coils and will be used in the verification of numerical coil models.

See, K. W.; Xu, X.; Horvat, J.; Cook, C. D.; Dou, S. X.

2012-11-01

308

Influence of Ion Bombardment onto Phosphor Layer on Temporal Image Sticking in Alternating-Current Plasma Display Panel  

NASA Astrophysics Data System (ADS)

We found that ion bombardment onto a phosphor layer during a sustained discharge was a key factor in inducing temporal image sticking of alternating-current (AC) plasma display panels (PDPs) through facilitated absorption of H2O onto the phosphor layer. We also found that ion bombardment onto the phosphor layer during the sustain discharge strongly depended on the bias conditions of the address electrode on which the phosphor layers were deposited. As a result, the positive-biased or floated address electrode condition could minimize the ion bombardment onto the phosphor layer during the sustain discharge, thus suppressing the absorption of H2O onto the phosphor layer, and ultimately preventing temporal image sticking.

Park, Choon-Sang; Kim, Sang-Yup; Jung, Eun-Young; Tae, Heung-Sik

2011-07-01

309

Elicitors as alternative strategy to pesticides in grapevine? Current knowledge on their mode of action from controlled conditions to vineyard.  

PubMed

Development and optimisation of alternative strategies to reduce the use of classic chemical inputs for protection against diseases in vineyard is becoming a necessity. Among these strategies, one of the most promising consists in the stimulation and/or potentiation of the grapevine defence responses by the means of elicitors. Elicitors are highly diverse molecules both in nature and origins. This review aims at providing an overview of the current knowledge on these molecules and will highlight their potential efficacy from the laboratory in controlled conditions to vineyards. Recent findings and concepts (especially on plant innate immunity) and the new terminology (microbe-associated molecular patterns, effectors, etc.) are also discussed in this context. Other objectives of this review are to highlight the difficulty of transferring elicitors use and results from the controlled conditions to the vineyard, to determine their practical and effective use in viticulture and to propose ideas for improving their efficacy in non-controlled conditions. PMID:23719689

Delaunois, Bertrand; Farace, Giovanni; Jeandet, Philippe; Clément, Christophe; Baillieul, Fabienne; Dorey, Stéphan; Cordelier, Sylvain

2013-05-30

310

Studies of Aliphatic Alcohol Oxidation Using Cyclic Voltammetry  

Microsoft Academic Search

Some aspects on aliphatic alcohols electro oxidation are presented, in order to establish the effect of various base electrolytes and different concentrations. The experiments involve to most used alcohols, like methanol, ethanol, propanol and buthanol, using cyclic voltammetry, rigorously established temperature and cleaned electrodes after each test, to minimize the variables.

Z. Urmosi; I. Balcu; M. Stefanut; I. Popa

2007-01-01

311

A Cyclic Voltammetry Experiment for the Instrumental Analysis Laboratory.  

ERIC Educational Resources Information Center

Background information and procedures are provided for experiments that illustrate the nature of cyclic voltammetry and its application in the characterization of organic electrode processes. The experiments also demonstrate the concepts of electrochemical reversibility and diffusion-controlled mass transfer. (JN)

Baldwin, Richard P.; And Others

1984-01-01

312

Optimization of square wave anodic stripping voltammetry (SWASV) for the simultaneous determination of Cd, Pb, and Cu in seawater and comparison with differential pulse anodic stripping voltammetry (DPASV).  

PubMed

Square wave anodic stripping voltammetry (SWASV) was optimized for the simultaneous determination of Cd, Pb and Cu in coastal seawater samples. Background subtraction was adapted to improve peak detection and quantification. Optimum background voltammograms were obtained by applying a 7.5 s equilibration potential at -975 mV (vs. Ag/AgCl, 3M KCl) before starting the background scan. Voltammetric scan parameters were optimized to obtain maximum sensitivity while retaining good peak resolution and discrimination from background. Optimal parameters were: frequency 100 Hz, pulse amplitude 25 mV, current sampling delay time 2 ms, step height 8 mV. The sensitivity of optimized SWASV proved to be more than double that of differential pulse anodic stripping voltammetry (DPASV), and analysis time was halved. Samples containing around 13 (Cd), 30 (Pb), 200 (Cu) ng/l (typical averages of the coastal area of the Marche region) can be analyzed using a 5 min deposition time and the total analysis time using three standard additions is about 1 h and half, excluding the mercury film preparation and the outgassing of the sample, which can be made in parallel using a second cell cup. PMID:12025515

Truzzi, Cristina; Lambertucci, Luca; Gambini, Gloria; Scarponi, Giuseppe

2002-03-01

313

Characterization of electrodeposited Cd–Co alloy coatings by anodic linear sweep voltammetry  

Microsoft Academic Search

The electrodeposited Cd–Co alloys were characterized by the anodic linear sweep voltammetry (ALSV) technique in the solution of 1M NaCl (pH 2). It is shown that Cd–Co alloys could be deposited with high current efficiency (>90%) from the solution containing 0.2M boric acid, low concentration of cadmium sulfate (0.01M and 0.02M) and high concentration of cobalt sulfate (0.2M and 0.4M)

B. M. Jovi?; Ts. Dobrovolska; U. La?njevac; I. Krastev; V. D. Jovi?

2009-01-01

314

Alternating Current Loss Characteristics in (Bi,Pb)2SrCa2Cu3O10 and YBa2Cu307-? Superconducting Tapes  

Microsoft Academic Search

Alternating current (AC) loss and current carrying capacity are two of the most crucial considerations in large-scale power applications of high temperature superconducting (HTS) conductors. AC losses result in an increased thermal load for cooling machines, and thus increased operating costs. Furthermore, AC losses can stimulate quenching phenomena or at least decrease the stability margin for superconducting devices. Thus, understanding

Doan Ngoc Nguyen

2007-01-01

315

currents  

Microsoft Academic Search

We give an alternative method to that of Hardy-Ramanujan-Rademacher to derive the leading exponential term in the asymptotic approximation to the partition function p(n, a), defined as the number of decompositions of a positive integer n into integer summands, with each summand appearing at most a times in a given decomposition. The derivation involves mapping to an equivalent physical problem

Miles P. Blencowe; Nicholas C. Koshnick

316

Detection of human leucocytes by cyclic voltammetry and its application to monitoring of allergic reaction.  

PubMed

Cyclic voltammetry was applied to the detection of human leucocytes and the monitoring of allergic reactions. A basal plane pyrolytic graphite electrode with attached leucocytes on a porous nitrocellulose membrane filter was employed as a working electrode. An anodic peak current appeared at 0.33 V versus the saturated calomel electrode (SCE) when the potential of the working electrode was scanned in the range of 0-1.0 V versus SCE. This peak current was attributed to the electrochemical oxidation of serotonin. When egg white was added to leucocytes obtained from patients who were allergic to egg, the peak current decreased owing to degranulation of leucocytes leading to serotonin release. The peak current decreased with increasing allergen concentration in the range of 5-50 micrograms ml-1. Leucocytes did not respond to other allergens such as soybean, milk and dinitrophenylated bovine serum albumin (DNP-BSA). PMID:1910667

Nakamura, N; Inoue, I; Kitajima, Y; Matsunaga, T; Chiba, T; Honda, T

1991-01-01

317

An analysis and discussion of the voltage and current spectrum of claw-pole alternators for fault detection purposes  

Microsoft Academic Search

The 'claw-pole' type synchronous alternator is the heart of virtually all automotive Electric Power Generation and Storage (EPGS) system. Timely and accurate detection of alternator faults will not only decrease \\

Siwei Cheng; Thomas G. Habetler

2011-01-01

318

Alternating current losses in mono- and multicored silver sheathed (Bi,Pb)2Sr2Ca2Cu3O10 tapes at T=27 K in direct current magnetic fields  

Microsoft Academic Search

Alternating current (ac) losses in silver sheathed mono- and multicored (Bi,Pb)2Sr2Ca2Cu3O10 superconducting tapes were investigated at liquid neon temperature (27 K) under various direct current (dc) background magnetic fields. The loss behavior was well accounted for by the Bean critical state model with the inclusion of eddy current loss in the silver sheath. The interfilamentary coupling loss was found to

Y. Fukumoto; H. J. Wiesmann; M. Garber; M. Suenaga; P. Haldar

1995-01-01

319

Alternating current losses in mono- and multicored silver sheathed (Bi,Pb)âSrâCaâCuâOââ tapes at {ital T}=27 K in direct current magnetic fields  

Microsoft Academic Search

Alternating current (ac) losses in silver sheathed mono- and multicored (Bi,Pb)âSrâCaâCuâOââ superconducting tapes were investigated at liquid neon temperature (27 K) under various direct current (dc) background magnetic fields. The loss behavior was well accounted for by the Bean critical state model with the inclusion of eddy current loss in the silver sheath. The interfilamentary coupling loss was found to

Y. Fukumoto; H. J. Wiesmann; M. Garber; M. Suenaga; P. Haldar

1995-01-01

320

NDT of on and offshore oil and gas installations using the alternating current field measurement (ACFM) technique  

SciTech Connect

Offshore inspection has been carried out in the UK waters for the last 25 years, but the techniques used have until recently remained stagnant. Innovative work carried out by University College London produced the mathematical modeling of the alternating current field measurement technique, which was then further developed and commercialized into a field usable technique. During detection and sizing trials, this technique proved to be better than even MPI for detection and as good as the existing sizing techniques. This was a major advance in NDT technology, a technique that could detect surface breaking defects through paint and other coatings of various thickness, then accurately size them in terms of length and depth. The technique was adopted for subsea inspection of welds and was then used for topside applications of numerous types. The adaptability of the technique to different materials and coatings has made it acceptable to not only the offshore industry, but it is now widely used in the petrochemical industry, the power generation industry, and in aerospace and outer space. A range of equipment and probes has allowed this new technology to be used where other techniques could not be applied.

Raine, G.A. [Technical Software Consultants Ltd., Milton Keynes (United Kingdom); Smith, N. [IESCO Inc., San Pedro, CA (United States)

1996-04-01

321

Pore formation in lipid bilayer membranes made of phosphatidylinositol and oxidized cholesterol followed by means of alternating current.  

PubMed Central

The kinetics of porin incorporation into black lipid membranes (BLM) made of phosphatidylinositol (PI) or oxidized cholesterol (Ox Ch) were studied by means of alternating current; the set-up was able to acquire resistance and capacitance simultaneously by means of a mixed double-frequency approach at 1 Hz and 1 KHz, respectively. Conductance was dependent on the interaction between protein-forming pores and lipids. For PI membranes below a porin concentration of 12.54 ng/ml, there was no membrane conductivity, whereas at 200 ng/ml a steady-state value was reached. Different behavior was displayed by Ox Ch membranes, in which a concentration of 12.54 ng/ml was sufficient to reach a steady state. The incorporation kinetics when porin was added after membrane formation were sigmoidal. When porin was present in the medium before membrane formation, the kinetics were sigmoidal for PI membranes but became exponential for Ox Ch membranes. Furthermore, for BLM made of PI, the conductance-versus-porin concentration relationship is sigmoidal, with a Hill coefficient of 5.6 +/- 0.07, which is functional evidence corroborating the six-channel repeating units seen previously. For BLM made of Ox Ch, this relationship followed a binding isotherm curve with a Hill coefficient of 0.934 +/- 0.129.

Gallucci, E; Micelli, S; Monticelli, G

1996-01-01

322

Alternating current electric fields of varying frequencies: effects on proliferation and differentiation of porcine neural progenitor cells.  

PubMed

Abstract Application of sinusoidal electric fields (EFs) has been observed to affect cellular processes, including alignment, proliferation, and differentiation. In the present study, we applied low-frequency alternating current (AC) EFs to porcine neural progenitor cells (pNPCs) and investigated the effects on cell patterning, proliferation, and differentiation. pNPCs were grown directly on interdigitated electrodes (IDEs) localizing the EFs to a region accessible visually for fluorescence-based assays. Cultures of pNPCs were exposed to EFs (1 V/cm) of 1?Hz, 10?Hz, and 50?Hz for 3, 7, and 14 days and compared to control cultures. Immunocytochemistry was performed to evaluate the expression of neural markers. pNPCs grew uniformly with no evidence of alignment to the EFs and no change in cell numbers when compared with controls. Nestin expression was shown in all groups at 3 and 7 days, but not at 14 days. NG2 expression was low in all groups. Co-expression of glial fibrillary acidic protein (GFAP) and TUJ1 was significantly higher in the cultures exposed to 10- and 50-Hz EFs than the controls. In summary, sinusoidal AC EFs via IDEs did not alter the alignment and proliferation of pNPCs, but higher frequency stimulation appeared to delay differentiation into mature astrocytes. PMID:23961767

Lim, Ji-Hey; McCullen, Seth D; Piedrahita, Jorge A; Loboa, Elizabeth G; Olby, Natasha J

2013-08-20

323

Complementary and Alternative Medicine: Comparison of Current Knowledge, Attitudes and Interest among German Medical Students and Doctors.  

PubMed

Although it has been agreed that complementary and alternative medicine (CAM) should be included in the German medical curriculum, there is no consensus on which methods and how it should be taught. This study aimed to assess needs for CAM education by evaluating current knowledge, attitudes and interests of medical students, general physicians and gynecologists. Two instruments based on established and validated questionnaires were developed. One was given to seventh semester medical students and the other to office-based doctors. Data were analyzed by bivariate correlation and cross-tabulation. Altogether 550 questionnaires were distributed-280 to doctors and 270 to medical students. Completed questionnaires were returned by 80.4% of students and 78.2% of doctors. Although 73.8% (160/219) of doctors and 40% (87/217) of students had already informed themselves about CAM, neither group felt that they knew much about CAM. Doctors believed that CAM was most useful in general medicine, supportive oncology, pediatrics, dermatology and gynecology, while students believed that dermatology, general medicine, psychiatry and rheumatology offered opportunities; both recommended that CAM should be taught in these areas. Both groups believed that CAM should be included in medical education; however, they believed that CAM needed more investigation and should be taught "critically". German doctors and students would like to be better informed about CAM. An approach which teaches fundamental competences to students, chooses specific content based on evidence, demographics and medical conditions and provides students with the skills they need for future learning should be adopted. PMID:19098296

Münstedt, Karsten; Harren, Hildegard; von Georgi, Richard; Hackethal, Andreas

2011-06-18

324

BRIEF COMMUNICATIONS: Gain and saturation parameter of a waveguide CO2 laser excited by a longitudinal alternating-current capacitance discharge  

Microsoft Academic Search

A determination was made of the dependences of the small-signal gain, saturation power, and gas temperature on the discharge tube diameter, working pressure, and discharge current in a waveguide CO2 laser excited by a longitudinal alternating-current (5-100 kHz) capacitance discharge. The results established that the scaling laws were applicable and a comparison was made of the efficiency of this excitation

V. V. Antyukhov; A. F. Glova; O. R. Kachurin; F. V. Lebedev; V. P. Yartsev

1985-01-01

325

Alternating current losses in stacked Bi2Sr2Ca2Cu3O10\\/Ag tapes in perpendicular magnetic fields  

Microsoft Academic Search

Alternating current losses in stacks of powder-in-tube-processed Bi2Sr2Ca2Cu3O10\\/Ag tapes were measured in perpendicular magnetic fields and compared with calculated hysteresis losses based on the critical-state model. Four main factors had to be taken into account for the calculations of the losses: (1) the inclusion of the area of the Ag sheath in determining the critical-current densities of the stacks, (2)

M. Suenaga; T. Chiba; S. P. Ashworth; D. O. Welch; T. G. Holesinger

2000-01-01

326

Correlation between the secondary electron emission coefficient of MgO protective layer and luminous efficiency in Alternating Current Plasma Display Panel (AC PDP)  

Microsoft Academic Search

Summary form only given. We have investigated the correlation between the secondary electron emission coefficient (gamma) of MgO protective layer and discharge luminous efficiency in alternating current plasma display panel (AC-PDP). We have fabricated the 4 inch PDP test panels with ITO gap distance of 60 mum, in which each PDP panel has respective their own secondary electron emission coefficient

Eun Young Park; Seung Jun Jung; Chang Gil Son; Ki Baek Song; Min Wook Moon; Phil Yong Oh; Byoung Hee Hong; Eun Ha Choi

2007-01-01

327

The 2?dimensional discharge cell simulation for the analysis of the peset and addressing of an alternating current plasma display panel  

Microsoft Academic Search

The characteristics of the reset and the address discharges of an alternating current Plasma Display Panel (ac PDP) were studied using 2?dimensional numerical discharge cell simulation. We investigated the wall charge variations during the reset discharge adopting ramping reset pulse and the subsequent addressing discharge. The roles of the ramping reset scheme can be divided into two stages, each electrode

Woo Jun Chung

2001-01-01

328

Vocational-Technical Physics Project. The Alternator: I. Current Electricity, II. Magnets from Electricity, III. Electricity from Magnets, IV. Energy Conversion. Field Test Edition.  

ERIC Educational Resources Information Center

This vocational physics individualized instructional student module on the alternator consists of the four units: Current electricity, magnets from electricity, electricity from magnets, and energy conversion. Designed with a laboratory orientation, the units present explanations of the concepts and experiments. Laboratory data sheets,…

Forsyth Technical Inst., Winston-Salem, NC.

329

Temporal behavior of the wall voltage in a surface-type alternating current plasma display panel cell using laser induced fluorescence spectroscopy  

Microsoft Academic Search

Electric fields were measured using laser induced fluorescence spectroscopy and the wall voltage was estimated from the measured electric fields in a surface-type alternating current plasma display panel cell with a helium discharge (100 Torr) driven by square sustaining pulses. The wall voltage showed very complicated, temporally dynamic behavior. The polarity of the wall voltage changed rapidly as soon as

Jung Hun Kim; Jun Hak Lee; Ki-Woong Whang; Young Wook Choi

2001-01-01

330

Determination of Sterically Hindered Phenols and ? -tocopherol by Cyclic Voltammetry  

Microsoft Academic Search

Sterically hindered phenols (2,6-di-tert-butyl-4-methylphenol (BHT) and its derivatives) are irreversibly oxidized at + 0.96-1.30 V on glassy carbon electrode (GCE) in 0.1 M LiCIO4 in acetonitrile in accordance to cyclic voltammetry data. ? -Tocopherol gives oxidation step at + 0.4 V on voltammograms under the same conditions. Oxidation process leads to formation of corresponding quinoid derivatives. Calibration graphs linearity is 1.5-2 order for all compounds under investigation.

Guzel Ziyatdinova; Aliya Khuzina; Herman Budnikov

2012-01-01

331

30 CFR 75.900 - Low- and medium-voltage circuits serving three-phase alternating current equipment; circuit...  

Code of Federal Regulations, 2010 CFR

...Underground Low- and Medium-Voltage Alternating...900 Low- and medium-voltage circuits...Provisions] Low- and medium-voltage power circuits serving...suitable circuit breakers of adequate interrupting...maintained as prescribed by the Secretary. Such...

2010-07-01

332

30 CFR 75.900 - Low- and medium-voltage circuits serving three-phase alternating current equipment; circuit...  

Code of Federal Regulations, 2010 CFR

...Underground Low- and Medium-Voltage Alternating...900 Low- and medium-voltage circuits...Provisions] Low- and medium-voltage power circuits serving...suitable circuit breakers of adequate interrupting...maintained as prescribed by the Secretary. Such...

2009-07-01

333

Surface ECE mechanism in protein film voltammetry—a theoretical study under conditions of square-wave voltammetry  

Microsoft Academic Search

For the first time, the features of a surface electron transfer–chemical reaction–electron transfer (ECE) mechanism, relevant\\u000a to protein-film set-up, have been studied theoretically under conditions of square-wave voltammetry. The considered surface\\u000a ECE mechanism is presented by following reaction scheme:$$A_{\\\\left( {{\\\\text{adsorbed}}} \\\\right)} + ne^ - \\\\rightleftarrows B_{\\\\left( {{\\\\text{adsorbed}}} \\\\right)} + Y\\\\xrightarrow{{k_{\\\\text{f}} }}C_{\\\\left( {{\\\\text{adsorbed}}} \\\\right)} + ne^ - \\\\rightleftarrows D_{\\\\left( {{\\\\text{adsorbed}}} \\\\right)}

Rubin Gulaboski

2009-01-01

334

Voltage biasing, cyclic voltammetry, & electrical impedance spectroscopy for neural interfaces.  

PubMed

Electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measure properties of the electrode-tissue interface without additional invasive procedures, and can be used to monitor electrode performance over the long term. EIS measures electrical impedance at multiple frequencies, and increases in impedance indicate increased glial scar formation around the device, while cyclic voltammetry measures the charge carrying capacity of the electrode, and indicates how charge is transferred at different voltage levels. As implanted electrodes age, EIS and CV data change, and electrode sites that previously recorded spiking neurons often exhibit significantly lower efficacy for neural recording. The application of a brief voltage pulse to implanted electrode arrays, known as rejuvenation, can bring back spiking activity on otherwise silent electrode sites for a period of time. Rejuvenation alters EIS and CV, and can be monitored by these complementary methods. Typically, EIS is measured daily as an indication of the tissue response at the electrode site. If spikes are absent in a channel that previously had spikes, then CV is used to determine the charge carrying capacity of the electrode site, and rejuvenation can be applied to improve the interface efficacy. CV and EIS are then repeated to check the changes at the electrode-tissue interface, and neural recordings are collected. The overall goal of rejuvenation is to extend the functional lifetime of implanted arrays. PMID:22395095

Wilks, Seth J; Richner, Tom J; Brodnick, Sarah K; Kipke, Daryl R; Williams, Justin C; Otto, Kevin J

2012-02-24

335

Amperometric detection of hydrazine by cyclic voltammetry and flow injection analysis using ruthenium modified glassy carbon electrodes  

Microsoft Academic Search

Glassy carbon electrodes modified with (5-amino-1,10-phenanthroline)bis(bipyridine)ruthium(II) chloride hydrate, [(bpy)2Ru(5-phenNH2)]Cl2·H2O, are shown to oxidize hydrazine with excellent sensitivity. The presence of an amine group on the ruthenium complex facilitates electropolymerization onto the electrode surface. Using cyclic voltammetry, a large catalytic current is observed upon oxidation of hydrazine in phosphate buffer (pH 5.0), compared to the current obtained from the ruthenium-modified electrode

Jill S. Pinter; Kenneth L. Brown; Paul A. DeYoung; Graham F. Peaslee

2007-01-01

336

Detection of Hypochlorous Acid Using Reduction Wave During Anodic Cyclic Voltammetry  

NASA Astrophysics Data System (ADS)

A novel analysis method for detecting low free-chlorine concentrations using a reduction wave based on anodic cyclic voltammetry has been developed. The reduction wave has been observed at approximately 600 mV vs Ag/AgCl, which is dependent on the free-chlorine concentration and switching potential. The wave peak showed a maximum value for the switching potential at approximately 1350 mV vs Ag/AgCl, and a good linear relationship between the peak current and the concentrations in the range of 0.2-6.0 mg dm-3. The relative standard deviation (RSD) at each concentration was less than 2%. This method seems to be useful for the analysis of low free-chlorine concentrations.

Kodera, Fumihiro; Umeda, Minoru; Yamada, Akifumi

2005-05-01

337

Electrochemical Dopamine Detection: Comparing Gold and Carbon Fiber Microelectrodes using Background Subtracted Fast Scan Cyclic Voltammetry  

PubMed Central

Electrochemical detection is becoming increasingly important for the detection of biological species. Most current biological research with electrochemical detection is done with carbon fiber electrodes due to their many beneficial properties. The ability to build electrochemical sensor from noble metals instead of carbon fibers may be beneficial in developing inexpensive multiplexed electrochemical detection schemes. To advance understanding and to test the feasibility of using noble metal electrochemical sensors the detection of dopamine, a biologically important small molecule was studied here. Specifically, dopamine detection on gold microelectrodes was characterized and compared to P-55 carbon fiber microelectrodes of the same geometry, using background subtracted fast scan cyclic voltammetry. While not as sensitive to dopamine as carbon fibers, it was observed that gold microelectrodes have six times the saturation coverage per area and 40 times the linear working range. Selectivity to dopamine, in comparison to several other neurotransmitters and their derivatives, is also quantitatively described.

Zachek, Matthew K.; Hermans, Andre; Wightman, R. Mark; McCarty, Gregory S.

2008-01-01

338

Weldability of thin sheet metals during small-scale resistance spot welding using an alternating-current power supply  

Microsoft Academic Search

The resistance weldability of 0.2-mm-thick sheet aluminum, brass, and copper in small-scale resistance spot welding (SSRSW)\\u000a was studied. The effects of electrode materials and process parameters on joint strength and nugget size were investigated.\\u000a The welding current ranges for SSRSW of the sheet metals were determined based on the minimum current that produced a required\\u000a nugget diameter and maximum currents

Y. Zhou; P. Gorman; W. Tan; K. J. Ely

2000-01-01

339

Alternating current magnetic susceptibility measurements in La1 - xSrxCoO3 (x <= 0.30) below 300 K  

Microsoft Academic Search

A dynamical magnetic susceptibility study on La1?xSrxCoO3 samples obtained by a coprecipitation method is reported for x?0.30. For x<0.20 differences between zero field cooled and field cooled dc magnetic susceptibility appear at a temperature Ta below the Curie point, TC≈240 K, as well as a magnetic freezing point at a temperature TbAlternating current magnetic susceptibility shows two maxima at

J. Mira; J. Rivas; R. D. Sánchez; M. A. Señarís-Rodríguez; D. Fiorani; D. Rinaldi; R. Caciuffo

1997-01-01

340

Transport measurements on positive-gap Hg1-xMnxTe with the use of an alternating-current technique  

Microsoft Academic Search

An alternating-current technique was used to measure the resistivity and Hall coefficient of single crystals of positive-gap Hg1-xMnxTe over the temperature range from 2 to 300 K and for magnetic fields up to 26 kG. In a p-type Hg0.81Mn0.19Te crystal, the resistivity and Hall coefficient were observed to decrease with increasing magnetic field for temperatures below 60 K. At 20

W. B. Johnson; J. R. Anderson; D. R. Stone

1984-01-01

341

A new system for measuring alternating current magnetic susceptibility of natural materials over a wide range of frequencies: A new rock magnetic property for environmental magnetism  

Microsoft Academic Search

A new measurement system has been developed for detecting frequency dependence of low-field alternating current (AC) magnetic susceptibility in natural samples. Instead of employing intricate AC bridge circuits, this system configuration is simple and consists of a set of primary, secondary (pick-up), and compensation coils, a function generator, and a two-phase lock-in amplifier. This system can measure both in-phase and

K. Kodama

2010-01-01

342

Accumulation and Decay Characteristics of Exoelectron Sources at MgO Protective Layer Surface in Alternating-Current Plasma Display Panels  

Microsoft Academic Search

The accumulation and decay characteristics of exoelectron sources at a MgO protective layer surface in alternating-current plasma display panels (AC-PDPs) were investigated. The positively charged MgO surface provides a larger number of exoelectrons than the negatively charged surface, indicating that electrons trapped in shallow carrier traps coexist with trapped holes, and exoelectrons are emitted through Auger and\\/or photoionization processes after

Kyohei Yoshino; Takaharu Nagatomi; Yukihiro Morita; Toshiyasu Oue; Naoki Kosugi; Mikihiko Nishitani; Masatoshi Kitagawa; Yoshizo Takai

2010-01-01

343

Correlation between the Secondary Electron Emission Coefficient of MgO Protective Layer and Luminous Efficiency in Alternating Current Plasma Display Panel (AC-PDP)  

Microsoft Academic Search

We have investigated the correlation between the secondary electron emission coefficient (?) of MgO protective layer and discharge luminous efficiency in alternating current plasma display panel (AC-PDP) by varying the O2 flowing rates of 0, 10, 20, and 30 sccm. It is found that the secondary electron emission coefficient and the brightness are maximum, and the discharge voltage is minimum at

Chang Gil Son; Young Gyu Han; Yoon Ki Kim; In Tae Kim; Guangsup Cho; Eun Ha Choi

2009-01-01

344

Influence of ZrO2 addition on the microstructure and discharge properties of Mg-Zr-O protective layers in alternating current plasma display panels  

Microsoft Academic Search

Mg-Zr-O protective layers for alternating current plasma display panels were deposited by e-beam evaporation. The effect of the ZrO2 addition on both the discharge properties [firing voltage Vf, minimum sustaining voltage Vs, and memory coefficient (MC)] and the microstructure of deposited Mg-Zr-O films were investigated. The results show that the film microstructure changes and the electron emission enhancement due to

Bingang Guo; Chunliang Liu; Zhongxiao Song; Liu Liu; Yufeng Fan; Xing Xia; Duowang Fan

2005-01-01

345

BRIEF COMMUNICATIONS: Investigation of the efficiency of pumping of fast-flow CO2 lasers by an alternating-current discharge  

Microsoft Academic Search

An experimental investigation was made of the efficiency of pumping of a fast-flow CO2 laser by an alternating-current discharge of 10 kHz frequency. A specific energy input of 300 J\\/g and a total vibrational efficiency of at least 50-60% were achieved in such a discharge. An analysis was made of the advantages of the proposed excitation method in various applications

V. D. Gavrilyuk; A. F. Glova; V. S. Golubev; F. V. Lebedev

1977-01-01

346

Simulations studies on influence of He concentration on discharge of alternating current plasma display panels in He-Ne-Xe mixture  

Microsoft Academic Search

With recent experiments to add He gas to the conventional Ne-Xe discharge gas mixture for high luminous efficiency plasma display panels, we have performed simulations on a coplanar structured alternating current plasma display panel sustained in the He-Ne-Xe gas mixture, by using the two-dimensional fluid model simulator. As the He concentration increases, luminance and luminous efficiencies increase but power consumption

Insook Lee; K. Y. Choi

2004-01-01

347

Spatiotemporal Behavior of Excited Xenon-Atom Density in Accordance With Xenon Mole Fraction to Neon in Alternating-Current Plasma Display Panels by Laser-Absorption Spectroscopy  

Microsoft Academic Search

In this paper, spatiotemporal behavior of the excited Xe-atom density of metastable state was investigated by laser-absorption spectroscopy in alternating-current plasma display panel in accordance with the Xe mole fraction to Ne, which can be connected to the relative luminous efficiency over all spaces in a discharge cell. The various test panels with Xe mole fractions of 4%, 7%, 10%,

Phil Yong Oh; Jung Hyun Kim; Youngjune Hong; Seok Ho Cho; Guangsup Cho; Eun Ha Choi

2008-01-01

348

A new method for simulation of on-chip interconnects and substrate currents with 3D alternating-direction-implicit (ADI) Maxwell solver  

Microsoft Academic Search

We introduce a time-domain method to simulate the digital signal propagation along on-chip interconnects by solving Maxwell's equations with the Alternating-Direction-Implicit (ADI) method. With this method, we are able to resolve the large scale (i.e. on-chip electromagnetic wave propagation) and fine scale (i.e. skin depth and substrate current) structure in the same simulation, and the simulation time step is not

Xi Shao; Neil Goldsman; Omar Ramahi; Parvez N. Guzdar

2003-01-01

349

Cyclic voltammetry and impedance studies of undoped diamond films  

NASA Astrophysics Data System (ADS)

The undoped, polycrystalline diamond films were deposited on tungsten wire substrates by hot filament chemical vapor deposition (HF CVD), using a precursor gas mixture of methanol with excess of hydrogen. The morphology and quality of the as-deposited films were monitored by scanning electron microscopy (SEM) and Raman spectroscopy. The surface morphology analyzed by SEM resembles a continuous and well faceted diamond film. Raman results showed essential differences in qualities of diamond films grown at different hydrocarbon concentrations. The electrochemical properties of diamond electrodes were examined with cyclic voltammetry (CV) and the electrochemical impedance spectroscopy (EIS). The CV experiments revealed a large chemical window (>˜4.3 V) of undoped diamond. Analysis of the ferrocyanide-ferricyanide couple at a diamond electrode suggests some extent of electrochemical quasi-reversibility, but the rates of charge transfer across the diamond substrate interface vary with diamond quality.

Mosi?ska, L.; Kowalska, M.; Popielarski, P.; Fabisiak, K.; Paprocki, K.; Szybowicz, M.; Wrzyszczy?ski, A.; Zhusupkalieva, G. K.

2013-01-01

350

Effects of switch mode power supply harmonic currents on building power systems and stand-by engine alternators  

Microsoft Academic Search

Power supplies drawing high peak currents are very common in today's buildings. These high peak currents contain the odd harmonics, and of special interest are the triplen harmonics-3, 9, 15, etc. Small power supplies are commonly connected from phase to neutral of the typical building power system. Engineers commonly distribute the loads among the phases to balance the building loads.

R. Plow

1994-01-01

351

Serum-protein effects on the detection of the beta-blocker propranolol by ion-transfer voltammetry at a micro-ITIES array.  

PubMed

In this work, the effect of the serum protein, bovine serum albumin (BSA), on the detection of propranolol in artificial serum by ion-transfer voltammetry at an array of micro-interfaces between two immiscible electrolyte solutions (microITIES) is presented. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and differential pulse stripping voltammetry (DPSV) were examined for the detection of low concentrations of propranolol. Both CV and DPV had an interference effect from BSA, manifested as lower currents in the presence of the protein. DPSV proved to be the most effective technique, enabling the detection of 0.05 microM propranolol in the presence of BSA. The DPSV method employed a preconditioning step as well as a preconcentration step followed by the analytical signal generation step. The latter was based on the back-transfer of the drug across the microITIES. The preconcentration step was crucial to prevention of the adverse effects of BSA on the voltammetric detection. These results demonstrate that serum-protein effects on drug detection at low concentrations can be eliminated by use of DPSV at arrays of microITIES. CVs of propranolol with increasing concentrations of BSA revealed the influence of the drug-protein binding interaction, with decreases in current but no change in transfer potential. Therapeutic concentrations of propranolol were detected, demonstrating the viability of this approach for bioanalytical investigations. PMID:20152444

Collins, Courtney J; Lyons, Conor; Strutwolf, Jörg; Arrigan, Damien W M

2009-11-10

352

De novo reconstruction of the Toxoplasma gondii transcriptome improves on the current genome annotation and reveals alternatively spliced transcripts and putative long non-coding RNAs  

PubMed Central

Background Accurate gene model predictions and annotation of alternative splicing events are imperative for genomic studies in organisms that contain genes with multiple exons. Currently most gene models for the intracellular parasite, Toxoplasma gondii, are based on computer model predictions without cDNA sequence verification. Additionally, the nature and extent of alternative splicing in Toxoplasma gondii is unknown. In this study, we used de novo transcript assembly and the published type II (ME49) genomic sequence to quantify the extent of alternative splicing in Toxoplasma and to improve the current Toxoplasma gene annotations. Results We used high-throughput RNA-sequencing data to assemble full-length transcripts, independently of a reference genome, followed by gene annotation based on the ME49 genome. We assembled 13,533 transcripts overlapping with known ME49 genes in ToxoDB and then used this set to; a) improve the annotation in the untranslated regions of ToxoDB genes, b) identify novel exons within protein-coding ToxoDB genes, and c) report on 50 previously unidentified alternatively spliced transcripts. Additionally, we assembled a set of 2,930 transcripts not overlapping with any known ME49 genes in ToxoDB. From this set, we have identified 118 new ME49 genes, 18 novel Toxoplasma genes, and putative non-coding RNAs. Conclusion RNA-seq data and de novo transcript assembly provide a robust way to update incompletely annotated genomes, like the Toxoplasma genome. We have used RNA-seq to improve the annotation of several Toxoplasma genes, identify alternatively spliced genes, novel genes, novel exons, and putative non-coding RNAs.

2012-01-01

353

Alternating-current susceptibility and critical-current density of melt-processed Gd-Ba-Cu-O-Ag single grains: effect of intrinsic edge pinning  

NASA Astrophysics Data System (ADS)

The field amplitude dependent complex ac susceptibility ?(Hm) of disc and square-planar samples cut from a Gd-Ba-Cu-O-Ag single grain fabricated by top-seeded melt growth (TSMG) has been measured at 77 K with the ac field applied along the crystallographic c axis of the single grain. The critical-current density Jc has been extracted from the measured ?(Hm) data based on the critical-state model assuming constant Jc. It is shown that Jc increases continuously with decreasing Hm, which is attributed to strong intrinsic pinning occurring at the edges of the sample.

Chen, D.-X.; Shi, Y.-H.; Navau, C.; Sanchez, A.; Cardwell, D. A.

2012-01-01

354

Detection of rat basophilic leukemia by cyclic voltammetry for monitoring allergic reaction.  

PubMed

Electrochemical detection of the rat basophilic leukemia (RBL-1) cells has been carried out by applying cyclic voltammetry. The detection system consists of a basal plane pyrolytic graphite electrode and a porous nitrocellulose membrane filter to trap RBL-1 cells. When the potential of the graphite electrode was run in the range of 0-1.0 V vs SCE, RBL-1 cells gave peak currents at 0.34 V vs SCE as well as 0.65 V vs SCE. There is a linear relationship between the peak current at 0.34 V vs SCE and the cell numbers of RBL-1. In the range of (0.4-2.0) X 10(5) cells. The peak current of RBL-1 cells was attributed to serotonin. When dinitrophenylated bovine serum albumin (DNP-BSA) as a model allergen was added to RBL-1 cells sensitized with anti-DNP IgE, the peak current decreased because of the degranulation of RBL-1 cells leading to serotonin release. On the other hand, RBL-1 cells sensitized with anti-DNP IgE did not respond to egg white, pollens, house dust, and milk. PMID:2479300

Matsunaga, T; Shigematsu, A; Nakamura, N

1989-11-15

355

Alternating current susceptibility measurements of inter-grain critical current density in sintered Bi1.8Pb0.2Sr2Ca2Cu3Oy  

NASA Astrophysics Data System (ADS)

The critical index of inter-grain penetration field Hp * was estimated for sintered Bi1.8 Pb0.2 Sr2 Ca2 Cu3 Oy high Tc superconductor by ac magnetic susceptibilities icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> ac .icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> 0 ´, real part of the linear icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> ac , showed two successive diamagnetic transitions at Tc = 107.8 K and Tc * = 104.6 K for intra- and inter-grain parts, respectively. Below Tc * , icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> 0 ´´, the imaginary part of the linear icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> ac , appeared and had a positive peak. The temperature and field dependences of icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> 0 ´´ below Tc * were analysed by the Bean critical state model for the slab geometry on the basis of qualitative agreements of real and imaginary third harmonic components, icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> 2 ´ and icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> 2 ´´, respectively. The obtained Hp * well reproduced the results of icons/Journals/Common/chi" ALT="chi" ALIGN="TOP"/> 0 ´. The critical index icons/Journals/Common/beta" ALT="beta" ALIGN="TOP"/> of inter-grain critical current density Jc * was estimated as 2.8 from the relation of Jc * icons/Journals/Common/propto" ALT="propto" ALIGN="TOP"/> Hp * icons/Journals/Common/propto" ALT="propto" ALIGN="TOP"/> (1-T /Tc * )icons/Journals/Common/beta" ALT="beta" ALIGN="TOP"/> . The large value of icons/Journals/Common/beta" ALT="beta" ALIGN="TOP"/> was significant for the present Bi2223 high Tc ceramics.

Kimishima, Y.; Inagaki, K.; Tanabe, K.; Ichiyanagi, Y.

2000-03-01

356

Harmonic flux penetration of superconductors in low-frequency, high-amplitude, alternating-current magnetic fields  

Microsoft Academic Search

A critical-state model has been used to calculate the magnetic response of a superconducting sample to an applied a.c. magnetic field. The analysis has been performed for both a cylindrical and a slab geometry and evaluated up to the tenth harmonic. It is shown that standard expressions derived using the critical-state model which relate the critical current density to the

H D Ramsbottom; D P Hampshire

357

STUDIES OF SUPERCONDUCTING Nb25% Zr WIRES CARRYING ALTERNATING CURRENT IN AN AXIALLY APPLIED MAGNETIC FIELD  

Microsoft Academic Search

The application of an axially directed magnetic field has been observed to reduce ac losses considerably in superconducting Nb-25% Zr wires. It has been found that magnetization curves measured with constant-amplitude ac flowing in a wire sample are paramagnetic-shifted with respect to curves measured with no externally supplied current. The presence of an axially applied field has been observed to

Henry F. Taylor

1967-01-01

358

Harmonic flux penetration of superconductors in low-frequency, high-amplitude, alternating-current magnetic fields  

Microsoft Academic Search

A critical-state model has been used to calculate the magnetic response of a superconducting sample to an applied a.c. magnetic field. The analysis has been performed for both a cylindrical and a slab geometry and evaluated up to the tenth harmonic. It is shown that standard expressions derived using the critical-state model which relate the critical current density to the

H. D. Ramsbottom; D. P. Hampshire

1997-01-01

359

Aneurysm Sac Pressure Measurement with Minimally Invasive Implantable Pressure Sensors: An Alternative to Current Surveillance Regimes after EVAR?  

Microsoft Academic Search

Current protocols for surveillance after endovascular repair (EVAR) of abdominal aortic aneurysms are mostly based on costly\\u000a and time-consuming imaging procedures and aim to detect adverse events such as graft migration, endoleaks or aneurysm sac\\u000a enlargement. These imaging procedures are either associated with radiation exposure to the patients or may be harmful to the\\u000a patient due to the use of

Fabian Springer; Rolf W. Günther; Thomas Schmitz-Rode

2008-01-01

360

Alternating current magnetic susceptibility measurements in La{sub 1-x}SrâCoOâ (xâ¤0.30) below 300 K  

Microsoft Academic Search

A dynamical magnetic susceptibility study on La{sub 1-x}SrâCoOâ samples obtained by a coprecipitation method is reported for xâ¤0.30. For x>0.20 differences between zero field cooled and field cooled dc magnetic susceptibility appear at a temperature T{sub a} below the Curie point, T{sub C}â240 K, as well as a magnetic freezing point at a temperature T{sub b}>T{sub a}. Alternating current magnetic

J. Mira; J. Rivas; R. D. Sanchez; M. A. Senaris-Rodriguez; D. Fiorani; D. Rinaldi; R. Caciuffo

1997-01-01

361

Effects of reduced fault duration upon power system components: a study of the feasibility of a greatly simplified alternative to the fault current limiter. Final report  

SciTech Connect

Practical means are needed to extend the fault current capacity of transmission substations. Since industry efforts to develop a true fault current limiting device have encountered serious technical and economic problems, a simpler solution is sought. In this report, the current concept of a protective scheme based upon fault limitation after the first current loop is formulated and examined in some detail as a viable alternative. Quantitative information from utilities and workshops has been compiled on both the industry needs and on the characteristics of actual fault currents. Consensus has been obtained on criteria for an acceptable protective scheme. . A test program has evaluated the ability of diverse contact structures to handle currents in excess of rating. The information learned to date is summarized and a specific 69KV application of the concept is considered in some detail. The present assessment suggests that 160% of rating will meet the needs and is attainable provided that appropriate back-up protection can be devised. This conclusion is based upon the statistical nature of fault characteristics; the practicality of limiting severe faults to a single current loop; and upon characteristics of the substation equipment. It is shown that the likelihood of subjecting circuit breakers to instantaneous currents in excess of close and latch rating is exceptionally rare. Tests have demonstrated the ability of circuit breakers with multiple finger contact structures to accommodate this duty without any difficulty. Approximate, analytical methods have been devised to assist in the rational identification of systems to which the proposed protection scheme can be applied. It is recommended that future efforts involve in depth studies of specific potential applications with cooperating utilities, and the development of adequate back-up protection procedures.

Barkan, P.

1982-12-01

362

ALTERNATING CURRENT LOSSES IN AG-SHEATHED BSCCO (2212 AND 2223) TAPES AND WIRES AND YBCO (123) COATED CONDUCTORS  

SciTech Connect

In this study, we focus on the examination of ac losses in conductors utilizing Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O [BSCCO (2223)] high TC superconductors (HTS). In addition, we seek to assist other facilities such as the University of Wisconsin-Madison Applied Superconductivity Center (UW-ASC), Brookhaven National Laboratory, and other DoE facilities investigating the use of HTS in electric power applications (e.g., generators, motors, and transformers). To accomplish this we will develop an ac losses capability at Clark Atlanta University to complement the established ac losses efforts at Brookhaven National Laboratory (BSCCO) on BSCCO/Ag and various material characterization efforts taking place at the UW-ASC. Our goal is through this effort to gain a greater understanding of the effects on ac losses due to parameters such as ac/dc current, J{sub c}, tape geometry, voltage tap placement, field orientation, material anisotropy, surface irregularities, percolations and filament coupling effects. As a result, we expect to better understand how to minimize ac losses in applications requiring real or practical conductors. HTS conductors based on BSCCO-2223 are now being routinely produced in industrial lengths of high quality. Vendors such as Southwire and ASC are producing multi-filamentary tapes in lengths of 6 km or more carrying critical current densities of up to 3 kA/cm**2 at 77 K. While this is approaching the level of performance where some large-scale applications are considered to be economically viable, a number of problems remain to be solved. The remaining issues include: rapid reduction in JC in magnetic fields; and power dissipation due to varying magnetic fields or currents (ac losses).

Dr. John S. Hurley

2000-01-01

363

Supplemental examination of alternative materials in a model steam generator: Volume 2, Correlation of Model 10 defects with eddy-current indications: Final report  

SciTech Connect

The following report compares the nondestructive examination with the destructive metallographic examination of the tube bundle alternative materials, Model 10 steam generator. The model steam generator was fabricated using state-of-the-art tube processing (Alloys 600, 690 and 800) and corrosion resistant support alloys and designs. The model steam generator was operated for approximately one year with a secondary environment that was faulted with acidified simulated cooling tower water and sludge. The tube bundle was eddy current tested at the final inspection using multiple frequency differential and absolute mode probes and state-of-the-art eddy current equipment, including a computerized system for data analysis. Various frequency mixes were designed to suppress signals from deposits and to improve signal to noise ratios. Special tests were utilized to evaluate the Alloy 800 tubing. Eddy current data correlated favorably with results from the destructive examinations. Generally eddy current tests were most successful in detecting axial cracks, circumferential cracks, defects with depths greater than 10% throughwall and tube denting at trefoil supports. It was not possible to distinguish between cracks and deep wastage. Interpretation of the eddy current indications predicted corrosion damage deeper than that found metallographically for conservative depth estimates. Numerous false defect indications, with low signal to noise ratios, were produced by the presence of conductive deposits on the O.D. of the tubing. Absolute mode testing provided a reliable qualitative indication of tube corrosion despite the interference from the conductive deposits. 4 refs., 1 fig., 1 tab.

Marugg, K.E.; Edwards, L.J.; Krupowicz, J.J.

1989-01-01

364

Solid electrolyte gas sensors based on cyclic voltammetry with one active electrode  

NASA Astrophysics Data System (ADS)

Solid state gas sensors are cost effective, small, rugged and reliable. Typically electrochemical solid state sensors operate in either potentiometric or amperometric mode. However, a lack of selectivity is sometimes a shortcoming of such sensors. It seems that improvements of selectivity can be obtained in case of the electrocatalytic sensors, which operate in cyclic voltammetry mode. Their working principle is based on acquisition of an electric current, while voltage ramp is applied to the sensor. The current-voltage response depends in a unique way on the type and concentration of ambient gas. Most electrocatalytic sensors have symmetrical structure. They are in a form of pellets with two electrodes placed on their opposite sides. Electrochemical reactions occur simultaneously on both electrodes. In this paper results for sensors with only one active electrode exposed to ambient gas are presented. The other electrode was isolated from ambient gas with dielectric sealing. This sensor construction allows application of advanced measuring procedures, which permit sensor regeneration acceleration. Experiments were conducted on Nasicon sensors. Properties of two sensors, one with one active electrode and second with symmetrical structure, used for the detection of mixtures of NO2 and synthetic air are compared.

Jasinski, G.; Jasinski, P.

2011-10-01

365

Ultra-sensitive quantification of copper in food and water samples by electrochemical adsorptive stripping voltammetry.  

PubMed

A new electrochemical adsorptive stripping voltammetry method was developed for the determination of trace amounts of copper in food and water samples. The study of electrochemical behavior of Cu ion indicated that Cu(II) and Schiff base formed a complex in H3BO4-NaOH buffer solution (pH?=?7.25). An accumulation potential of -100 mV (vs Ag/AgCl) was applied while the solution was stirred for 60 s. The response curve was recorded by scanning the potential, and the peak current of -0.31 V (vs Ag/AgCl) was recorded. The peak current and concentration of copper accorded with linear relationship in the range of 0.04-120 ng mL(-1). The relative standard deviation (for 12 ng mL(-1) of copper) was 1.73 %, and the detection limit was 0.007 ng mL(-1). The possible interference of some common ions was studied. The proposed method was applied to the determination of copper in water, rice, wheat, tea, milk, and tomato with satisfactory results. PMID:23625354

Goudarziafshar, Hamid; Nikoorazm, Mohsen; Mortazavi, Sayede Shima; Abbasi, Shahryar; Farmany, Abbas

2013-04-27

366

Determination of lead in an Sb-Pb alloy by anodic linear scan voltammetry.  

PubMed

Anodic linear scan voltammetry (ALSV) has been used to determine the content of Pb (up to 3.5 wt%) in a eutectic type of binary Sb-Pb alloy. The effect of type of electrolyte and as well as the rate of the potential change on the dissolution of Pb from this alloy were investigated by ALSV. The method can be used for the determination of low concentrations of Pb in the investigated alloy and well-defined current peaks of Pb dissolution can be detected on the voltammograms. Well-de-fined linear dependencies between the quantities of electricity under the current peak of Pb dissolution (QPb) and the respective contents of Pb (w) in the alloy, so-called "check curves", were found. The smallest ratio of Pb in Sb-Pb alloy which could be detected by ALSV was 0.45 wt%. The dissolution involves only ten atomic layers of the less precious metal (Pb) from the surface of the alloy samples. PMID:11769792

Blagojevi?, N Z; Kastratovi?, V R; Zejnilovi?, R M; Bleci?, Z

2001-12-01

367

Iron organic speciation determination in rainwater using cathodic stripping voltammetry.  

PubMed

A sensitive method using Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) has been developed to determine for the first time iron (Fe) organic speciation in rainwater over the typical natural range of pH. We have adapted techniques previously developed in other natural waters to rainwater samples, using the competing ligand 1-nitroso-2-naphthol (NN). The blank was equal to 0.17±0.05 nM (n=14) and the detection limit (DL) for labile Fe was 0.15 nM which is 10-70 times lower than that of previously published methods. The conditional stability constant for NN under rainwater conditions was calibrated over the pH range 5.52-6.20 through competition with ethylenediaminetetraacetic acid (EDTA). The calculated value of the logarithm of ?'(Fe(3+)(NN)(3)) increased linearly with increasing pH according to log ?'(Fe(3+)(NN)(3)) (salinity=2.9, T=20 °C). The validation of the method was carried out using desferrioxamine mesylate B (DFOB) as a natural model ligand for Fe. Adequate detection windows were defined to detect this class of ligands in rainwater with 40 ?M of NN from pH 5.52 to 6.20. The concentration of Fe-complexing natural ligands was determined for the first time in three unfiltered and one filtered rainwater samples. Organic Fe-complexing ligand concentrations varied from 104.2±4.1 nM equivalent of Fe(III) to 336.2±19.0 nM equivalent of Fe(III) and the logarithm of the conditional stability constants, with respect to Fe(3+), varied from 21.1±0.2 to 22.8±0.3. This method will provide important data for improving our understanding of the role of wet deposition in the biogeochemical cycling of iron. PMID:22769004

Cheize, Marie; Sarthou, Géraldine; Croot, Peter L; Bucciarelli, Eva; Baudoux, Anne-Claire; Baker, Alex R

2012-05-19

368

The voltammetry–photocurrent response study of passivation of carbon steel in slightly alkaline solutions containing the corrosion inhibitor phosphor-polymaleic acid–ZnSO 4  

Microsoft Academic Search

The electro-oxidation\\/electro-reduction processes on the surface of a carbon steel electrode were studied in borate buffer solutions (pH=8.4) in the presence and absence of the corrosion inhibitor phosphor-polymaleic acid (PPMA)–ZnSO4 at room temperature by using the voltammetry–photocurrent response method. For the carbon steel electrode in solutions containing the corrosion inhibitor, its voltammograms displayed a smaller oxidation peak current and a

Yi-Jiu Li; Bin Wu; Xin-Ping Zeng; Ya-Fei Liu; Ya-Ming Ni; Guo-Ding Zhou; Hong-Hua Ge

2002-01-01

369

Evaluation of current pharmacological treatment options in the management of rett syndrome: from the present to future therapeutic alternatives.  

PubMed

Neurodevelopmental disorders are a large family of conditions of genetic or environmental origin that are characterized by deficiencies in cognitive and behavioral functions. The therapeutic management of individuals with these disorders is typically complex and is limited to the treatment of specific symptoms that characterize each disorder. The neurodevelopmental disorder Rett syndrome (RTT) is the leading cause of severe intellectual disability in females. Mutations in the gene encoding the transcriptional regulator methyl-CpG-binding protein 2 (MECP2), located on the X chromosome, have been confirmed in more than 95% of individuals meeting diagnostic criteria for classical RTT. RTT is characterized by an uneventful early infancy followed by stagnation and regression of growth, motor, language, and social skills later in development. This review will discuss the genetics, pathology, and symptoms that distinguish RTT from other neurodevelopmental disorders associated with intellectual disability. Because great progress has been made in the basic and clinical science of RTT, the goal of this review is to provide a thorough assessment of current pharmacotherapeutic options to treat the symptoms associated with this disorder. Furthermore, we will highlight recent discoveries made with novel pharmacological interventions in experimental preclinical phases, and which have reversed pathological phenotypes in mouse and cell culture models of RTT and may result in clinical trials. PMID:24050745

Chapleau, Christopher A; Lane, Jane; Pozzo-Miller, Lucas; Percy, Alan K

2013-11-01

370

The Generalized Standard Addition Method: Intermetallic Interferences in Anodic Stripping Voltammetry.  

National Technical Information Service (NTIS)

A barrier to routine application of anodic stripping voltammetry is the possible formation of intermetallic compounds which can lead to significant errors in the estimated analyte concentrations. As the well known method of standard additions can correct ...

R. W. Gerlach B. R. Kowalski

1981-01-01

371

Ultrasonic Extraction/Anodic Stripping Voltammetry for Determining Lead in Household Paint: A Laboratory Evaluation.  

National Technical Information Service (NTIS)

A laboratory study was conducted to evaluate the reliability of commercial, field-portable ultrasonic extraction-anodic stripping voltammetry (UE/ASV) for determining the lead levels of laboratory-prepared paint films when tests were performed by certifie...

W. J. Rossiter M. G. Vangel M. E. McKnight A. Signor W. E. Byrd

2001-01-01

372

Thin film voltammetry of wild type and mutant reaction center proteins from photosynthetic bacteria.  

PubMed

Photosynthetic reaction centers (RC) convert light into electrical potential via a series of electron transfers between protein-bound, redox-active cofactors. Direct voltammetry was used to characterize the RC protein from Rhodobacter sphaeroides and mutants with focus on the primary electron donor (P) cofactor. Cyclic voltammetry (CV) and square wave voltammetry (SWV) of lipid and polyion films of RCs revealed similar chemically irreversible processes, and starting, switching, or preconditioning potential of -0.15 V was required to observe a well-defined P/P(+) oxidation peak at ?0.95 V versus normal hydrogen electrode. An irreversible chemical reaction following voltammetric oxidation led to peak decreases upon multiple scans. Mutant RCs with site-directed amino acid modifications in the vicinity of P displayed shifts of oxidation peak potential correlated with those reported from redox titrations. These studies illustrate the utility of thin film voltammetry in characterizing redox properties of bound cofactors in RC proteins. PMID:21384836

Zhang, Yun; LaFountain, Amy M; Magdaong, Nikki; Fuciman, Marcel; Allen, James P; Frank, Harry A; Rusling, James F

2011-03-08

373

Protein film voltammetry: electrochemical enzymatic spectroscopy. A review on recent progress  

Microsoft Academic Search

This review is focused on the basic principles, the main applications, and the theoretical models developed for various redox\\u000a mechanisms in protein film voltammetry, with a special emphasis to square-wave voltammetry as a working technique. Special\\u000a attention is paid to the thermodynamic and kinetic parameters of relevant enzymes studied in the last decade at various modified\\u000a electrodes, and their use

Rubin Gulaboski; Valentin Mir?eski; Ivan Bogeski; Markus Hoth

374

Using square-wave voltammetry to monitor molten alkaline fluoride baths for electrodeposition of niobium  

Microsoft Academic Search

This study implemented an electrochemical analysis method, square-wave voltammetry, to monitor the molten fluoride (LiF?NaF) baths which are used for electrolytic deposition of niobium. This method makes it possible to perform qualitative and quantitative analyses of the niobium species in situ at different degrees of oxidation and to determine the content of oxygenated niobium compounds. Square-wave voltammetry was first compared

Pierre Chamelot; Bernard Lafage; Pierre Taxil

1997-01-01

375

Measurement of kinetically resolved vesicular dopamine uptake and efflux using rotating disk electrode voltammetry  

Microsoft Academic Search

The vesicular monoamine transporter-2 (VMAT-2) sequesters cytoplasmic dopamine (DA) into vesicles for storage and subsequent release. VMAT-2 activity has traditionally been measured in small synaptic vesicles isolated from rat striatum by monitoring [3H] DA uptake and in cellular expression systems using fast scan cyclic voltammetry. This is the first report using rotating disk electrode (RDE) voltammetry to measure VMAT-2 DA

Trent J. Volz; Glen R. Hanson; Annette E. Fleckenstein

2006-01-01

376

A new design of carbon fiber microelectrode for in vivo voltammetry using fused silica.  

PubMed

Voltammetric probes were constructed from stainless steel and fused silica tubing sheathing carbon fibers. Electrochemical tests were carried out to compare these electrodes with commercially available glass-sealed IVEC-5 electrodes. Electrodes of both types displayed a similar declining baseline and calculated coefficients of stabilization (tangent of baseline during a stable period). There were no significant differences in sensitivity between the two designs of electrodes to norepinephrine (NE) and dopamine (DA). All tested electrodes showed linear current responses to increasing concentrations of NE and DA. Fused silica (FS type) electrodes are suitable for electrochemical measurements (in vivo voltammetry) and display characteristics similar to those of commercially available IVEC-5 glass-sealed carbon fiber microelectrodes. Manufacture of FS type electrodes in a biochemical laboratory is easy and does not require any special equipment (such as a micropipette puller) or glass-handling skills. An additional fused silica tube can be glued to the electrode for microinjections. The electrodes are very robust, easy to handle and can be mounted on the arms of standard stereotaxic instruments. The electrodes can be made long enough to reach the deepest parts of brain of large animals. PMID:9130675

Swiergiel, A H; Palamarchouk, V S; Dunn, A J

1997-04-25

377

Square wave voltammetry at disc microelectrodes for characterization of two electron redox processes.  

PubMed

Analytical explicit solutions are presented for the use of square wave voltammetry (SWV) at disc microelectrodes to study two-electron reversible redox processes. This combines the advantages of SWV (minimization of capacitative effects, peak-shaped response and quick experiments) with those of microelectrodes (reduction of capacitative and ohmic drop effects, enhanced mass transport and measurements of small volumes). Further, the analytical expressions are very easy to implement in comparison with the numerical methods usually employed for simulation of electrochemical experiments at microdisc electrodes. From the theory, the effects of the technique parameters (frequency, pulse amplitude) are examined and procedures are given for the characterization of the redox system from the values of the peak current, peak potential and half-peak width. Finally, the theory is applied to the experimental study of the two-electron reduction of anthraquinone-2-sulfonate in aqueous media. For this system, the formal potentials of the redox centres in aqueous solutions can be tuned by means of the electrolyte cation. PMID:22580390

Laborda, E; Molina, A; Li, Q; Batchelor-McAuley, C; Compton, R G

2012-05-11

378

Investigations of drug-DNA interactions using molecular docking, cyclic voltammetry and UV-Vis spectroscopy  

NASA Astrophysics Data System (ADS)

Molecular docking and QSAR studies were carried out for the investigation of interactions between 11 antitumor drugs and double stranded DNA. Quantitative structure activity relationship was established using MOE software package showing good correlation of binding strength with various physicochemical parameters e.g., hydrophobic surface area (Vsurf), EHOMO, EHUMO, partition coefficient (log P) and molar refractivity (MR) of the drugs.The most important parameter obtained from the docking studies was the formation constant (Kf) which is an indicative of the binding strength of the drug with DNA. This parameter was also calculated using the experimental techniques namely cyclic voltammetry (CV) and UV-Vis spectrophotometry. Variation in electrochemical characteristics (shift in peak potential and peak current decrease) and spectral profile of these drugs on the addition of DNA were used to determine the values of formation constant. The docking studies were used to predict the mode of interaction of the drug with DNA. It was observed that as far as binding strength was concerned the computational results complemented the experimental results. The order of magnitude of experimental and theoretical Kf was same. The high value of Kf implied that the respective drugs bind to DNA most efficiently.

Perveen, Fouzia; Qureshi, Rumana; Ansari, Farzana Latif; Kalsoom, Saima; Ahmed, Safeer

2011-10-01

379

New approach to electrode kinetic measurements in square-wave voltammetry: amplitude-based quasireversible maximum.  

PubMed

The influence of the potential pulse height of square-wave voltammetry (SWV) (i.e., the SW amplitude) is studied for a variety of quasireversible electrode mechanisms, including a simple solution-phase electrode reaction at a planar or spherical electrode, a solution phase electrode reaction coupled with a reversible follow-up chemical reaction, and a diffusionless surface confined electrode reaction. The electrode kinetics of all the electrode mechanisms depends critically on the SW amplitude, and the quasireversible kinetic region is a function of both frequency-related electrode kinetic parameters and the SW amplitude. Thus, a novel methodology for electrode kinetics measurements is proposed by altering the SW amplitude only, at a fixed frequency of the SW potential modulation, that is, at a constant scan rate of the voltammetric experiment. Electrode kinetic measurements at a constant SW frequency are of exceptional importance especially when complex electrode mechanisms are studied, which depend on several frequency-related kinetic parameters. The electrode kinetic measurements are based on a novel feature termed the "amplitude-based quasireversible maximum", manifested as a parabolic dependence of the amplitude-normalized net SW peak current versus the SW amplitude. The position of the amplitude-based quasireversible maximum depends on the standard rate constant of the electrode reaction, enabling estimation of this important kinetic parameter in a simple and fast procedure. The novel quasireversible maximum is attributed to all studied electrode mechanisms, implying that it is a general feature of most electrode mechanisms under conditions of SWV. PMID:23642036

Mirceski, Valentin; Laborda, Eduardo; Guziejewski, Dariusz; Compton, Richard G

2013-05-23

380

Determination of verapamil by adsorptive stripping voltammetry in urine and pharmaceutical formulations.  

PubMed

A sensitive reduction peak of verapamil is obtained by adsorptive stripping voltammetry in 0.01 M phosphate (pH 7.4) at an accumulation time of 30 s. The peak potential is -1.81 V (vs. Ag/AgCl). The peak current is directly proportional to the concentration of verapamil (1x10(-8)-1x10(-6) M), with a 3sigma detection limit of 5x10(-10) M (0.246 ng/ml). The R.S.D. at the 1x10(-7) M level is 1.8%. The interference of some metal ions, and some amino acids, and the application of the method to analysis of urine, and pharmaceutical formulations are described. The method is simple (no extraction), rapid (30 s accumulation time), sensitive (the detection limit of verapamil is 0.491 ng/ml), reproducible(within day R.S.D. of 1.28-1.8%), and suitable for routine analysis of verapamil, urine, and pharmaceutical formulation. PMID:12408881

Kasim, Ensaf Aboul; Ghandour, M A; El-Haty, M T; Ahmed, Mahasen M

2002-11-01

381

Electrode modification using porous layers. Maximising the analytical response by choosing the most suitable voltammetry: Differential Pulse vs Square Wave vs Linear sweep voltammetry  

Microsoft Academic Search

The analytical benefits obtained from electrode modification with conductive porous layers, a common practice in the development of electrochemical (bio)sensors, are examined for the main electroanalytical techniques: differential pulse, square wave and linear sweep voltammetry.The electrochemical response is analyzed in terms of the effect of the modification on the electrode kinetics and on the diffusion transport of the target species.

Eduardo Laborda; Angela Molina; Francisco Martínez-Ortiz; Richard G. Compton

382

Accumulation and Decay Characteristics of Exoelectron Sources at MgO Protective Layer Surface in Alternating-Current Plasma Display Panels  

NASA Astrophysics Data System (ADS)

The accumulation and decay characteristics of exoelectron sources at a MgO protective layer surface in alternating-current plasma display panels (AC-PDPs) were investigated. The positively charged MgO surface provides a larger number of exoelectrons than the negatively charged surface, indicating that electrons trapped in shallow carrier traps coexist with trapped holes, and exoelectrons are emitted through Auger and/or photoionization processes after their recombination. The exoelectron sources are accumulated by sustain discharges and always decay. The half-life of the decay of the exoelectron sources is relatively long, of the order of a few tens of ms, confirming that the exoelectron emission property at the address discharge in a certain television (TV) field is strongly affected by sustain firings in the previous two TV fields or more. The effects of such a long-term decay of the exoelectron sources should be taken into consideration when designing the driving waveforms of AC-PDPs.

Yoshino, Kyohei; Nagatomi, Takaharu; Morita, Yukihiro; Oue, Toshiyasu; Kosugi, Naoki; Nishitani, Mikihiko; Kitagawa, Masatoshi; Takai, Yoshizo

2010-08-01

383

Galvinoxyl monolayers on Au(111) studied by STM, EPR, and cyclic voltammetry  

NASA Astrophysics Data System (ADS)

Galvinoxyl layers on Au(111) have been studied by scanning tunnelling microscopy (STM), electron paramagnetic resonance (EPR), and cyclic voltammetry (CV). We observe two phases: configuration I having a molecular density of 1.57±0.16×10-10mol/cm2 and a rectangular lattice ( 15Å by 7Å ) observed at room temperature and down to 140K ; configuration II with a slightly smaller molecular density of 1.37±0.14×10-10mol/cm2 and oblique cells ( 22.5Å by 5.4Å ) arranged alternatingly in stacks yielding a molecular layer with lower symmetry and comparatively large crystallographic unit cell. The latter is only observed upon cooling down to 40K and subsequent annealing to room temperature. For both assemblies typical domain sizes in the range of 100nm have been found. The EPR results confirm that the radical character is preserved upon adsorption and that the intermolecular distance is smaller than 11Å . The interaction between the overlapping singly occupied spin orbitals is high, indicating no participation of the unpaired electron in the binding to the surface or laterally between neighboring radicals. The average surface concentration deduced from CV measurements is in excellent agreement with the surface coverages deduced from STM topographies. In aqueous electrolyte the adsorbate undergoes a one-electron oxidation with concomitant loss of a proton as determined from oxidation potential vs pH curves in a similar fashion as known for the free radical in solution. This indicates no dramatic change of the electronic properties of the radical upon adsorption. Structure models are proposed with molecules standing upright like “bicycles in rows.”

Niermann, Natascha; Degefa, Tesfaye Hailu; Walder, Lorenz; Zielke, Vitali; Steinhoff, Heinz-Jürgen; Onsgaard, Jens; Speller, Sylvia

2006-12-01

384

Rectified Alternating-Current Converter.  

National Technical Information Service (NTIS)

A half-wave and a voltage multiplying rectifier circuit is provided in which the full smoothing and regulating advantages of a filter inductor are realized. This is accomplished in a half-wave rectifier circuit by applying the rectified output of an alter...

G. F. Montgomery

1965-01-01

385

Serum-protein effects on the detection of the ?-blocker propranolol by ion-transfer voltammetry at a micro-ITIES array  

Microsoft Academic Search

In this work, the effect of the serum protein, bovine serum albumin (BSA), on the detection of propranolol in artificial serum by ion-transfer voltammetry at an array of micro-interfaces between two immiscible electrolyte solutions (?ITIES) is presented. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and differential pulse stripping voltammetry (DPSV) were examined for the detection of low concentrations of propranolol.

Courtney J. Collins; Conor Lyons; Jörg Strutwolf; Damien W. M. Arrigan

2010-01-01

386

A simultaneous study of kinetics and thermodynamics of anion transfer across the liquid/liquid interface by means of Fourier transformed large-amplitude square-wave voltammetry at three-phase electrode.  

PubMed

This paper describes a novel application of Fourier transformed large-amplitude square-wave voltammetry (FT-SWV) in combination with three-phase edge plane pyrolytic graphite (EPPG) electrode to investigate both the kinetics and thermodynamics of anion transfer across the liquid/liquid interface using a conventional three-electrode arrangement. The transfer of anion from aqueous phase to organic phase was electrochemically driven by reversible redox transformation of confined redox probe in the organic phase. The kinetics and thermodynamics of anion transfer were inspected by a so-called "quasi-reversible maximum" (QRM) emerged in the profile of even harmonic components of power spectrum obtained by Fourier transformation (FT) of time-domain total current response and formal potential E(f) of first harmonic voltammogram obtained by application of inverse FT on the power spectrum. Besides, a systematic study of patterns of behavior of a variety of anions at the same concentration and a specific anion at different concentrations on kinetics and thermodynamics and the effect of amplitude ?E on QRM were also conducted, aiming to optimize the measurement conditions. The investigation mentioned above testified that the ion transfer across the liquid/liquid interface controls the kinetics of overall electrochemical process, regardless of either FT-SWV or traditional SWV investigation. Moreover, either the kinetic probe f(max) or the thermodynamic probe E(f) can be served as a way for analytical applications. Interestingly, a linear relationship between peak currents of the first harmonic components and concentrations of perchlorate anion in the aqueous solutions can be observed, which is somewhat in accordance with a finding obtained by Fourier transformed alternating current voltammetry (FT-ACV) [Bond, A. M.; Duffy, N. W.; Elton, D. M.; Fleming, B. D. Anal. Chem. 2009, 81, 8801-8808]. This may open a new door for analytical detection of a wide spectrum of electrochemically inactive analytes of biological and environmental significance. Compared with traditional SWV, FT-SWV is much simpler and faster in ion transfer kinetics estimation and also provides a new access to thermodynamics evaluation. PMID:21082797

Deng, Haiqiang; Huang, Xinjian; Wang, Lishi

2010-11-17

387

Factors controlling stripping voltammetry of lead at polycrystalline boron doped diamond electrodes: new insights from high-resolution microscopy.  

PubMed

We report wide-ranging studies to elucidate the factors and issues controlling stripping voltammetry of metal ions on solid electrodes using the well-known Pb/Pb(2+) couple on polycrystalline boron doped diamond (pBDD) as an exemplar system. Notably, high-resolution microscopy techniques have revealed new insights into the features observed in differential pulse anodic stripping voltammetry (DPV-ASV) which provide a deeper understanding of how best to utilize this technique. DPV-ASV was employed in an impinging wall-jet configuration to detect Pb(2+) in the nanomolar to micromolar concentration range at a pBDD macrodisk electrode. The deposition process was driven to produce a grain-independent homogeneous distribution of Pb nanoparticles (NPs) on the electrode surface; this resulted in the observation of narrow stripping peaks. Lower calibration gradients of current or charge versus concentration were found for the low concentrations, correlating with a lower than expected (from consideration of the simple convective-diffusive nature of the deposition process) amount of Pb deposited on the surface. This was attributed to the complex nature of nucleation and growth at solid surfaces in this concentration regime, complicating mass transport. Furthermore, a clear shift negative in the stripping peak potential with decreasing concentration was seen correlating with a change in the size of the deposited NP, suggesting an NP size-dependent redox potential for the Pb/Pb(2+) couple. At high concentrations a nonlinear response was observed, with less Pb detected than expected, in addition to the observation of a second stripping peak. Atomic force microscopy (AFM) and field emission scanning electron microscopy revealed the second peak to be due to a change in deposition morphology from isolated NPs to grain-independent heterogeneous structures comprising both thin films and NPs; the second peak is associated with stripping from the thin-film structures. AFM also revealed a substantial amount of Pb remaining on the surface after stripping at high concentration, explaining the nonlinear relationship between stripping peak current (or charge) and concentration. Finally, the use of an in situ cleaning procedure between each measurement was advocated to ensure a clean Pb-free surface (verified by AFM and X-ray photoelectron spectroscopy analysis) between each run. The studies herein highlight important and complex physicochemical processes involved in the electroanalysis of heavy metals at solid electrodes, such as pBDD, that need to be accounted for when using stripping voltammetry methods. PMID:21214184

Hutton, Laura A; Newton, Mark E; Unwin, Patrick R; Macpherson, Julie V

2011-01-07

388

Quantitative Analysis of Trace Chromium in Blood Samples. Combination of the Advanced Oxidation Process with Catalytic Adsorptive Stripping Voltammetry  

PubMed Central

A new method for pretreating blood samples for trace Cr analysis is described. The Advanced Oxidation Process (AOP with H2O2 and 5.5-W irradiation for 60 min) is used to remove biological/organic species for subsequent analysis. Prior to the AOP pretreatment, acid (HNO3) is used at pH 3.0 to inhibit the enzyme catalase in the blood samples. Catalytic Adsorptive Stripping Voltammetry (CAdSV) at a bismuth film electrode (BiFE) gives Cr concentration of 6.0 ± 0.3 ppb in the blood samples. This concentration was confirmed by dry-ashing the blood samples and subsequent analysis by atomic absorption spectroscopy (AAS). This current method may be used to monitor chromium, a trace metal in humans, and the efficacy and safety of chromium supplements as adjuvant therapy for diabetes.

Yong, Li; Armstrong, Kristie C.; Dansby-Sparks, Royce N.; Carrington, Nathan A.; Chambers, James Q.; Xue*, Zi-Ling

2007-01-01

389

LBM for cyclic voltammetry of electrochemically mediated enzyme reactions and Rayleigh-Bénard convection in electrochemical reactors  

NASA Astrophysics Data System (ADS)

A few of the applications of the Lattice Boltzmann Method have been used to model the complex bioelectrochemical phenomena presented here; cyclic voltammetry of electrically assisted enzyme reactions for one instance, and complex chemical reactions with simultaneous momentum, heat and mass transfer as another example. In the first case, we reproduce experimental data and predict new results (not feasible of being obtained by other numerical methods); the evolution of the diffusion boundary layer, which is important information from the numerical viewpoint to design reactors. As second, our model of non isothermal electrochemical enzyme reactor with a complex chemical-thermohydrodynamics involves an enzyme reaction taking place over two parallel rectangular enzyme immobilized electrodes, within a Rayleigh-Bénard convection system, a multifaceted subject not yet studied simultaneously. Realistic velocity, temperature, and concentration profiles as well as the corresponding Faradaic currents for different geometries and heating settings are provided, showing the goodness of our approach.

Amaya-Ventura, G. A.; Rodríguez-Romo, S.

2012-02-01

390

Adsorptive-catalytic stripping voltammetry for determination of ultratrace titanium.  

PubMed

An extremely sensitive stripping voltammetric procedure for determination of ultratrace titanium is reported. The method is based on the interfacial preconcentration of titanium-cupferron complex onto the hanging mercury drop electrode, followed by catalytic reduction of the adsorbed complex for the presence of cupferron. The peak currents are directly proportional to titanium in the ranges of 0.06-1.0 ng/ml and 1.0-30.0 ng/ml. Moreover, the character of stripping current has also been studied with various polarographic methods. Such coupling of catalytic and adsorptive collection processes holds great promise for the development of an ultrasensitive voltammetric procedure for other metals. PMID:18965961

Baoxian, Y; Shuxun, Y

1994-04-01

391

Application of Low-Frequency Alternating Current Electric Fields Via Interdigitated Electrodes: Effects on Cellular Viability, Cytoplasmic Calcium, and Osteogenic Differentiation of Human Adipose-Derived Stem Cells  

PubMed Central

Electric stimulation is known to initiate signaling pathways and provides a technique to enhance osteogenic differentiation of stem and/or progenitor cells. There are a variety of in vitro stimulation devices to apply electric fields to such cells. Herein, we describe and highlight the use of interdigitated electrodes to characterize signaling pathways and the effect of electric fields on the proliferation and osteogenic differentiation of human adipose-derived stem cells (hASCs). The advantage of the interdigitated electrode configuration is that cells can be easily imaged during short-term (acute) stimulation, and this identical configuration can be utilized for long-term (chronic) studies. Acute exposure of hASCs to alternating current (AC) sinusoidal electric fields of 1?Hz induced a dose-dependent increase in cytoplasmic calcium in response to electric field magnitude, as observed by fluorescence microscopy. hASCs that were chronically exposed to AC electric field treatment of 1?V/cm (4?h/day for 14 days, cultured in the osteogenic differentiation medium containing dexamethasone, ascorbic acid, and ?-glycerol phosphate) displayed a significant increase in mineral deposition relative to unstimulated controls. This is the first study to evaluate the effects of sinusoidal AC electric fields on hASCs and to demonstrate that acute and chronic electric field exposure can significantly increase intracellular calcium signaling and the deposition of accreted calcium under osteogenic stimulation, respectively.

McCullen, Seth D.; McQuilling, John P.; Grossfeld, Robert M.; Lubischer, Jane L.; Clarke, Laura I.

2010-01-01

392

Evaluation of plasma low molecular weight antioxidant capacity by cyclic voltammetry.  

PubMed

The low molecular weight antioxidants (LMWA) of biological samples include many compounds and contribute to the total antioxidant capacity of the system. They act as direct chemical scavengers neutralizing, reactive oxygen-derived species (ROS), and contribute to the ability of the sample to cope with oxidative stress. We propose cyclic voltammetry (CV) as a new method for evaluating the antioxidant capacity of plasma-LMWA and the severity of oxidative stress exerted on the plasma. It is based on the reducing properties of these molecules. CV has been proven to be a simple, sensitive and reliable method. Its tracing does not change during storage of frozen plasma for up to six months. We analyzed the CV tracings by the oxidation potential E1/2, and the current heights Ia of its anodic wave(s). E1/2 indicates the specific component of the LMWA and its ability to donate electron(s); Ia indicates the concentration of this component. Two anodic waves have been identified in human plasma, at E1/2 = 420 +/- 25 and 920 +/- 25 mV. Ascorbate (AA) and urate (UA) were identified as major LMWA components of the first anodic wave, and were confirmed by HPLC-electrochemical detection. Ia was shown to depend linearly on the concentration of either of these LMWA, both in buffer and in plasma. Oxidative stress exerted by exposure to peroxyl radicals, copper ions and ionizing irradiation caused marked changes in the CV tracing. These changes represent corresponding alterations particularly in la, rather than in E1/2. The Ia and E1/2 values reflect the antioxidant capacity of the plasma, while the change of Ia value represents the severity of the oxidative stress induced. PMID:8981032

Chevion, S; Berry, E M; Kitrossky, N; Kohen, R

1997-01-01

393

Determination of allura red in some food samples by adsorptive stripping voltammetry.  

PubMed

Square wave (SW) voltammetry was used to explore the adsorption properties of the food additive dye Allura Red on a hanging mercury drop electrode (HMDE). By using the adsorptive stripping voltammetric approach, we developed a sensitive electroanalytical method for the determination of this azo dye. A well-developed voltammetric peak probably related to the cathodic reduction of the azo moiety was obtained in pH 9 Britton-Robinson (B-R) buffer at 613 mV. Cyclic voltammetric studies indicated that the reduction process was irreversible and primarily controlled by adsorption. The adsorptive voltammetric signal was evaluated with respect to various experimental conditions; the optimized values were supporting electrolyte, B-R buffer; pH 11; accumulation time, 180 s; accumulation potential, 0.0 V; scan rate, 900 mV/s; pulse amplitude, 75 mV; and SW frequency, 90 Hz. Adsorptive voltammetric peak current showed a linear response for Allura Red in the concentration range of 2.5 x 10(-8) to 2.0 x 10(-7) mol/L (r = 0.998). The limit of detection was 8.5 x 10(-9) mol/L (4.2 ng/mL), the precision in terms of relative standard deviation was 1.3%, and the mean recovery was 102%. Possible interferences by several substances usually present in food products such as food additive azo dyes (E110, E102), gelatin, natural and artificial sweeteners, preservatives, and antioxidants were also evaluated. The proposed electrochemical procedure was successfully applied to the determination of this food dye in commercially available candy and a soft drink. The results were compared by statistical evaluation with those obtained by a reference spectrophotometric method. PMID:16385987

Alghamdi, Ahmad H

394

Suppression of surfactant interferences in anodic stripping voltammetry by sodium dodecyl sulfate  

Microsoft Academic Search

It was investigated whether interferences from surfactants in anodic stripping voltammetry (ASV) could be remedied by the anionic surfactant sodium dodecyl sulfate (SDS) which causes little or no interference in itself. Cadmium and lead were used as test analytes, and measurements were performed in acetate buffer as well as in 0.1 M HNO3. One hundred parts per million of the

Boy Hoyer; Nina Jensen

2003-01-01

395

Microbial Biofilm Voltammetry: Direct Electrochemical Characterization of Catalytic Electrode-Attached Biofilms  

Microsoft Academic Search

While electrochemical characterization of enzymes immobilized on electrodes has become common, there is still a need for reliable quantitative methods for study of electron transfer between living cells and conductive surfaces. This work describes growth of thin (<20 m) Geobacter sulfurreducens biofilms on polished glassy carbon electrodes, using stirred three-electrode anaerobic bioreactors controlled by potentiostats and nonde- structive voltammetry techniques

Enrico Marsili; Janet B. Rollefson; Daniel B. Baron; Raymond M. Hozalski; Daniel R. Bond

2008-01-01

396

Identification of iron(III) oxides and hydroxy-oxides by voltammetry of immobilised microparticles  

Microsoft Academic Search

In this paper, we propose the use of an electroanalytical technique based on the direct oxidation or reduction of the electroactive components of the sample on the surface of the working electrode, called voltammetry of immobilised microparticles (VMPs). The sample is easily deposited on the electrode by abrasion and then the electrode is transferred to the electrochemical cell where the

G Cepriá; A Usón; J Pérez-Arantegui; J. R Castillo

2003-01-01

397

The influence of promoter and of electrode material on the cyclic voltammetry of Pisum sativum plastocyanin  

Microsoft Academic Search

The reversible cyclic voltammetry of pea plastocyanin (Pisum sativum) was studied with a wide range of electrodes: edge-oriented pyrolytic graphite (PGE), glassy carbon (GCE), gold (Au) and platinum (Pt) electrodes. Plastocyanin was coated onto the electrode surface by exploiting the electrostatic interaction between the negatively charged protein and a wide range of positively charged promoters. The effect of the redox

D. L Johnson; C. J Maxwell; D Losic; J. G Shapter; L. L Martin

2002-01-01

398

Determination of lead in an Sb-Pb alloy by anodic linear scan voltammetry  

Microsoft Academic Search

Anodic linear scan voltammetry (ALSV) has been used to determine the content of Pb (up to 3.5 wt%) in a eutectic type of binary Sb-Pb alloy. The effect of type of electrolyte and as well as the rate of the potential change on the dissolution of Pb from this alloy were investigated by ALSV. The method can be used for

N. Blagojevi?; V. Kastratovi?; R. Zejnilovi?; Ž. Ble?i?

2001-01-01

399

Differential cyclic voltammetry - a novel technique for selective and simultaneous detection using redox cyling based sensors  

Microsoft Academic Search

Redox cycling (RC) is an effect that is used to amplify electrochemical signals. However, traditional techniques such as cyclic voltammetry (CV) do not provide clear insight for a mixture of multiple redox couples while RC is applied. Thus, we have developed a new measurement technique which delivers electrochemical spectra of all reversible redox couples present based on concentrations and standard

M. Odijk; J. Wiedemair; M. J. J. van Megen; W. Olthuis; A. van den Berg

2010-01-01

400

Lead-Testing Service to Elementary and Secondary Schools Using Anodic Stripping Voltammetry  

ERIC Educational Resources Information Center

The undergraduate chemistry club of the Southwest Minnesota State University offers assistance in lead-testing through the anodic stripping voltammetry (ASV) technique to elementary and secondary schools. Emphasis is given to this community service activity, which has increased club membership, and promoted discussion of water quality problems in…

Goebel, Amanda; Vos, Tracy; Louwagie, Anne; Lundbohm, Laura; Brown, Jay H.

2004-01-01

401

Adsorptive Stripping Voltammetry of Environmental Indicators: Determination of Zinc in Algae  

ERIC Educational Resources Information Center

|A method for sample preparation and for the determination of average zinc content in algae using adsorptive stripping voltammetry are described. The students gain important didactic advantages through metal determination in environmental matrices, which include carrying out clean protocols for sampling and handling, and digesting samples using…

Collado-Sanchez, C.; Hernandez-Brito, J. J.; Perez-Pena, J.; Torres-Padron, M. E.; Gelado-Caballero, M. D.

2005-01-01

402

Direct determination of dextran in sugar juices from sugar refining processes by stripping voltammetry  

Microsoft Academic Search

Dextran has been determined in sugar juices from beet sugar refining processes by differential?pulse cathodic stripping voltammetry (DPCSV) at the hanging mercury drop electrode (HMDE). Measurements were performed on diluted samples without previous treatment. The optimised procedure allowed the direct determination of dextran at the mg?kg level. The performance of the procedure is compared with the Roberts copper method.

D. Sancho; L. Debán; L. Martínez; R. Pardo; M. Vega

1998-01-01

403

Measuring mercury ion concentration with a carbon nano tube paste electrode using the cyclic voltammetry method  

Microsoft Academic Search

A simply prepared carbon nano tube paste electrode (CNTPE) was utilized for monitoring mercury ion concentration using the cyclic voltammetry (CV) method and the square wave anodic stripping voltammetric (SWASV) method. The CNTPE was compared with various conventional electrodes. The CNTPE method was applied to determine the concentration of trace levels of Hg(II) in several water samples, which yielded a

Suw Young LY; Sung Kuk Kim; Tae Hyun Kim; Young Sam Jung; Sang Min Lee

2005-01-01

404

Determination of Ascorbic Acid by Electrocatalytic Voltammetry with Methylene Blue  

Microsoft Academic Search

A rapid voltammetric method was developed for the determination of l-ascorbate using methylene blue as a mediator with a glassy carbon electrode. The magnitude of the peak current that occurs near ?0.04 V vs. Ag\\/AgCl is proportional to l-ascorbate concentration in the range of 1.2 × 10 to 1.12 × 10 M. The limit of detection is 1 × 10 M. Eight replicate analyses of 5.0 × 10 M and 4.5 × 10 M l-ascorbate yielded

Ali A. Ensafi

2003-01-01

405

The Green Phosphor SrAl2O4:Eu2+, R3+ (R=Y, Dy) and its Application in Alternating Current Light-Emitting Diodes  

NASA Astrophysics Data System (ADS)

The aim of the present investigation was to develop a phosphor to solve the flickering luminescence of alternating current (AC) light-emitting diodes (LED) by compensating the dark duration with appropriately persistent luminescence. The phosphor SrAl2O4:Eu2+ co-doped with Y3+ or Dy3+ was synthesized via solid-state reaction with H3BO3 as flux. The crystal structure and morphology were characterized by using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM), respectively. The photoluminescence spectra were collected with a fluorescence spectrometer. The results demonstrated that appropriate amount of Y3+ or DY3+ doped was beneficial to suppress the by-product of Sr4Al14O25 which easily co-existed with the SrAl2O4 phase brought by the flux of H3BO3. However, too much Y3+ or DY3+ doped resulted in the formation of another impurity phase, i.e., the yttrium aluminum garnet of Y3Al5O12 and Dy3Al5O12. Comparatively, the doped DY3+ was more helpful in prolonging the persistent luminescence, while Y3+ was more efficient in enhancing luminescence intensity. To demonstrate the feasibility of the phosphor applied in AC LEDs, a nearly white AC LED was fabricated by coating the phosphor on a blue AC LED chip. The persistent luminescence was radiated from the AC LED device after turning power off. Moreover, the effect of the phosphor on compensating the AC LED dark duration through persistent luminescence was revealed by using the Keyence VW-9000 High-speed Microscope for the first time.

Chen, Lei; Zhang, Yao; Xue, Shaochan; Deng, Xiaorong; Anqi; Luo; Liu, Fayong; Jiang, Yang; Chen, Shifu; Bahader, Ali

2013-08-01

406

Visualization of local electrochemical activity and local nickel ion release on laser-welded NiTi/steel joints using combined alternating current mode and stripping mode SECM.  

PubMed

Smoothly polished cross-sections of laser-fabricated welds between NiTi shape memory alloy and stainless steel (SS) microwires of approximately the same diameter and, for comparison, between identical stainless steel or NiTi wires have been subjected to local chemical activity and nickel release measurements using scanning electrochemical microscopy (SECM). In the alternating current mode (AC-SECM), the measurements detected clear differences in the local interfacial chemical activity of the passivated weld and the base metals only for the heterogeneous joints of the type NiTi-SS. In this case the local electrochemical acvtivity was lower above the weld material. Subjecting cross-sections of NiTi-SS to stripping mode SECM (SM-SECM), higher Ni(2+) concentrations were measured above the regions of the parental NiTi wire, which correlates well with the results from AC-SECM imaging which showed this region as being less passivated. An energy-dispersive elemental analysis of the specimen in a scanning electron microscope revealed the coexistence of Ti and Cr in the weld mass. Possibly, a joint action of these two metals in terms of protective oxide formation is better for passivation of the weld region than the individual action of one or the other element for passivating the original wires. Better passivation of course led to decreased electrochemical activity of the weld surface. Apparently, AC- and SM-mode SECM imaging were sufficiently sensitive to detect and visualize the impact of the changed surface passivation upon laser welding. PMID:19082072

Ruhlig, D; Gugel, H; Schulte, A; Theisen, W; Schuhmann, W

2008-09-23

407

A randomized, double-blind, sham-controlled study of static electric field therapy by high voltage alternating current for active rheumatoid arthritis  

PubMed Central

Static electric field therapy by high voltage alternating current (EF-HVAC) is a traditional complementary Japanese medicine used for headache, shoulder stiffness, chronic constipation and insomnia. Open-label studies and clinical experience in Japan have suggested that this electric field therapy is safe and effective in treating chronic arthritis. We evaluated the efficacy of EF-HVAC therapy in a randomized, double-blinded, sham-controlled trial in patients with active rheumatoid arthritis (RA) in community-based general physician centers. Thirty patients fulfilling American College of Rheumatology (ACR) criteria for RA were treated with EF-HVAC therapy with the LEGACIS PLUS System (COCOROCA Corp., Tokyo, Japan) or sham therapy for 12 weeks and followed for 4 weeks without treatment. The disease activity score 28 (DAS28-CRP), visual analogue scale for pain (VAS), modified health assessment questionnaire (MHAQ), and inflammatory parameters were used as the outcome variable. Twenty four patients (n = 12 in each group) were analyzed by a per protocol analysis. Although a significant reduction in DAS28-CRP was observed in EF-HVAC group at 8 and 12 weeks compared to before treatment, there were no significant differences in DAS28-CRP scores during treatment between two groups. The scale of VAS was also significantly decreased by the treatment with EF-HVAC compared to before treatment, in addition, the scale of VAS in EF-HVAC group was significantly lower than sham group at 8 and 12 weeks. Changes in another parameters including MHAQ were not significant between before and after treatment, or by all comparative study between two groups. There were no adverse events related the treatment. In conclusion, the EF-HVAC therapy has a beneficial effect on the improvement to subjective pain of RA.

Naito, Yuji; Yamaguchi, Shinnichi; Mori, Yasuhiro; Nakajima, Kouji; Hashimoto, Sanshiro; Tomaru, Masakazu; Satoh, Yoshihiko; Hitomi, Yuji; Karita, Masakazu; Hiwatashi, Tomoaki; Kawahito, Yutaka; Yoshikawa, Toshikazu

2013-01-01

408

A randomized, double-blind, sham-controlled study of static electric field therapy by high voltage alternating current for active rheumatoid arthritis.  

PubMed

Static electric field therapy by high voltage alternating current (EF-HVAC) is a traditional complementary Japanese medicine used for headache, shoulder stiffness, chronic constipation and insomnia. Open-label studies and clinical experience in Japan have suggested that this electric field therapy is safe and effective in treating chronic arthritis. We evaluated the efficacy of EF-HVAC therapy in a randomized, double-blinded, sham-controlled trial in patients with active rheumatoid arthritis (RA) in community-based general physician centers. Thirty patients fulfilling American College of Rheumatology (ACR) criteria for RA were treated with EF-HVAC therapy with the LEGACIS PLUS System (COCOROCA Corp., Tokyo, Japan) or sham therapy for 12 weeks and followed for 4 weeks without treatment. The disease activity score 28 (DAS28-CRP), visual analogue scale for pain (VAS), modified health assessment questionnaire (MHAQ), and inflammatory parameters were used as the outcome variable. Twenty four patients (n = 12 in each group) were analyzed by a per protocol analysis. Although a significant reduction in DAS28-CRP was observed in EF-HVAC group at 8 and 12 weeks compared to before treatment, there were no significant differences in DAS28-CRP scores during treatment between two groups. The scale of VAS was also significantly decreased by the treatment with EF-HVAC compared to before treatment, in addition, the scale of VAS in EF-HVAC group was significantly lower than sham group at 8 and 12 weeks. Changes in another parameters including MHAQ were not significant between before and after treatment, or by all comparative study between two groups. There were no adverse events related the treatment. In conclusion, the EF-HVAC therapy has a beneficial effect on the improvement to subjective pain of RA. PMID:23874073

Naito, Yuji; Yamaguchi, Shinnichi; Mori, Yasuhiro; Nakajima, Kouji; Hashimoto, Sanshiro; Tomaru, Masakazu; Satoh, Yoshihiko; Hitomi, Yuji; Karita, Masakazu; Hiwatashi, Tomoaki; Kawahito, Yutaka; Yoshikawa, Toshikazu

2013-04-19

409

Anterior clinoidectomy: Description of an alternative hybrid method and a review of the current techniques with an emphasis on complication avoidance  

PubMed Central

Background: Anterior clinoidectomy is a difficult but important part of surgery for a variety of parasellar, proximal carotid and central skull base pathologies. First developed intradurally nearly 60 years ago, the promotion of an extradural technique decades later offered an approach with a different set of difficulties, risks and benefits. Many recent studies have demonstrated that there is no consensus about the “correct side” of the dura from which to remove the anterior clinoid process in a number of pathologies. Here, we review and compare the current techniques for intra- and extradural clinoidectomy and describe a hybrid alternative technique. Methods: We used a hybrid method to potentially engage the advantages of the intradural and extradural techniques. The hybrid method starts with an extradural sphenoid wing osteotomy to the level of the superior orbital fissure (SOF). The dura is then incised parallel to the sphenoid wing lateral to the SOF, and the need for further bony removal, including clinoidectomy, is assessed after gentle elevation of the frontal lobe and release of cerebrospinal fluid through opening the optico-carotid cisterns and inspection of the pathology in relation to the clinoid. Sylvian fissure may be dissected to relieve retraction on the frontal lobe. Results: The hybrid method allows an early identification of the optic nerve and its protection during clinoidectomy. The operator leaves the dura medial to the SOF intact and the clionoidectomy proceeds in an extradural fashion while intradural inspection periodically is performed to assess the extent of necessary extradural bony removal. Conclusion: The hybrid method theoretically can be used as a versatile method under some circumstances. Cutting the dura along the sphenoid wing will prevent the dural layers from obscuring the clinoid and offers intradural visualization to monitor the lesion and potentially tailor bony removal.

Kulwin, Charles; Tubbs, R. Shane; Cohen-Gadol, Aaron A.

2011-01-01

410

Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy  

Microsoft Academic Search

The effect of the SnO2 nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified

Mihrican Muti; Arzum Erdem; Ayfer Caliskan; Ali S?nag; Tugrul Yumak

2011-01-01

411

Spatiotemporal behavior of excited Xe atom density in the 1s5 metastable state according to the Xe mole fractions in He-Ne-Xe ternary gas mixtures at alternating current plasma display panel(AC-PDP)  

Microsoft Academic Search

Summary form only given. We have measured the excited Xe atom density in the ls5 metastable state in accordance with Xe mole fraction to He and Ne in alternating current plasma display panels by laser absorption spectroscopy. The various test panels with Xe mole fractions of 4, 7, 10 and 15 % to He-Ne have been used in this experiment.

P. Y. Oh; J. H. Kim; Y. J. Hong; S. H. Cho; B. H. Hong; G. S. Cho; E. H. Choi

2008-01-01

412

A Wireless IC for Wide-Range Neurochemical Monitoring Using Amperometry and Fast-Scan Cyclic Voltammetry.  

PubMed

An integrated circuit for real-time wireless monitoring of neurochemical activity in the nervous system is described. The chip is capable of conducting measurements in both fast-scan cyclic voltammetry (FSCV) and amperometry modes for a wide input current range. The chip architecture employs a second-order DeltaSigma modulator (DeltaSigmaM) and a frequency-shift-keyed transmitter operating near 433 MHz. It is fabricated using the AMI 0.5-mum double-poly triple-metal n-well CMOS process, and requires only one off-chip component for operation. A measured current resolution of 12 pA at a sampling rate of 100 Hz and 132 pA at a sampling rate of 10 kHz is achieved in amperometry and 300-V/s FSCV modes, respectively, for any input current in the range of plusmn430 nA. The modulator core and the transmitter draw 22 and 400 muA from a 2.6-V power supply, respectively. The chip has been externally interfaced with a carbon-fiber microelectrode implanted acutely in the caudate-putamen of an anesthetized rat, and, for the first time, extracellular levels of dopamine elicited by electrical stimulation of the medial forebrain bundle have been successfully recorded wirelessly using 300-V/s FSCV. PMID:23852628

Roham, M; Daberkow, D P; Ramsson, E S; Covey, D P; Pakdeeronachit, S; Garris, P A; Mohseni, P

2008-03-01

413

Highly sensitive determination of trace copper in food by adsorptive stripping voltammetry in the presence of 1,10-phenanthroline.  

PubMed

A highly sensitive, rapid, simple and selective adsorptive stripping assay for the determination of trace copper(II) is proposed. The methodology is based on the adsorptive accumulation of copper(II)-1,10-phenanthroline complexes onto a glassy carbon electrode, followed by oxidation of the adsorbed species by voltammetric scanning using square-wave voltammetry. The influences of experimental variables on the sensitivity of the proposed method, such as the effects of pH, ligand concentration, accumulation time, accumulation potential and interferences, were investigated. Under optimal conditions, the proposed method showed linearity from 0.1 ng mL(-1) to 50 ng mL(-1). The 3 S/N detection limits were 0.0185 ng mL(-1), and the relative standard deviations (n=10) were 0.09-4.71% for intra-day and 0.05-7.14% for inter-day analyses, respectively. The application of the proposed method to the direct analysis of food samples yielded results that agreed with those obtained from including inductively coupled plasma-optical emission spectrometry (ICP-OES) assays according to a paired t-test. The results are a step toward the development of an alternative and reliable analytical method for food research, which requires the direct determination of copper. PMID:23601862

Chaiyo, Sudkate; Chailapakul, Orawon; Sakai, Tadao; Teshima, Norio; Siangproh, Weena

2013-03-05

414

Detection and classification of gaseous sulfur compounds by solid electrolyte cyclic voltammetry of cermet sensor array.  

PubMed

Electrochemical sensors composed of a ceramic-metallic (cermet) solid electrolyte are used for the detection of gaseous sulfur compounds SO(2), H(2)S, and CS(2) in a study involving 11 toxic industrial chemical (TIC) compounds. The study examines a sensor array containing four cermet sensors varying in electrode-electrolyte composition, designed to offer selectivity for multiple compounds. The sensors are driven by cyclic voltammetry to produce a current-voltage profile for each analyte. Raw voltammograms are processed by background subtraction of clean air, and the four sensor signals are concatenated to form one vector of points. The high-resolution signal is compressed by wavelet transformation and a probabilistic neural network is used for classification. In this study, training data from one sensor array was used to formulate models which were validated with data from a second sensor array. Of the 11 gases studied, 3 that contained sulfur produced the strongest responses and were successfully analyzed when the remaining compounds were treated as interferents. Analytes were measured from 10 to 200% of their threshold-limited value (TLV) according to the 8-h time weighted average (TWA) exposure limits defined by the National Institute of Occupational Safety and Health (NIOSH). True positive classification rates of 93.3, 96.7, and 76.7% for SO(2), H(2)S, and CS(2), respectively, were achieved for prediction of one sensor unit when a second sensor was used for modeling. True positive rates of 83.3, 90.0, and 90.0% for SO(2), H(2)S, and CS(2), respectively, were achieved for the second sensor unit when the first sensor unit was used for modeling. Most of the misclassifications were for low concentration levels (such 10-25% TLV) in which case the compound was classified as clean air. Between the two sensors, the false positive rates were 2.2% or lower for the three sulfur compounds, 0.9% or lower for the interferents (eight remaining analytes), and 5.8% or lower for clean air. The cermet sensor arrays used in this analysis are rugged, low cost, reusable, and show promise for multiple compound detection at parts-per-million (ppm) levels. PMID:17386588

Kramer, Kirsten E; Rose-Pehrsson, Susan L; Hammond, Mark H; Tillett, Duane; Streckert, Holger H

2006-11-12

415

Electrochemical Genotoxicity Assay Based on a SOS/umu Test Using Hydrodynamic Voltammetry in a Droplet  

PubMed Central

The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the ?-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples containing a high concentration of colored dissolved organic matters, sediment, and suspended solids. However, umu tests with electrochemical detection techniques prove to be a better strategy because it causes less interference, enables the analysis of turbid samples and allows detection even in small volumes without loss of sensitivity. Based on this understanding, we aim to develop a new umu test system with hydrodynamic chronoamperometry using a rotating disk electrode (RDE) in a microliter droplet. PAPG when used as a substrate is not electroactive at the potential at which PAP is oxidized to p-quinone imine (PQI), so the current response of chronoamperometry resulting from the oxidation of PAP to PQI is directly proportional to the enzymatic activity of S. typhimurium. This was achieved by performing genotoxicity tests for 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2) and 2-aminoanthracene (2-AA) as model genotoxic compounds. The results obtained in this study indicated that the signal detection in the genotoxicity assay based on hydrodynamic voltammetry was less influenced by the presence of colored components and sediment particles in the samples when compared to the usual colorimetric signal detection. The influence caused by the presence of humic acids (HAs) and artificial sediment on the genotoxic property of selected model compounds such as 4-nitroquinoline-N-oxide (4-NQO), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), 1,8-dinitropyrene (1,8-DNP) and 1-nitropyrene (1-NP) were also investigated. The results showed that the genotoxicity of 1-NP and MX changed in the presence of 10 mg·L?1 HAs. The genotoxicity of tested chemicals with a high hydrophobicity such as 1,8-DNP and 1-NP were decreased substantially with the presence of 1 g·L?1 sediment. This was not observed in the case of genotoxins with a low log Kow value.

Kuramitz, Hideki; Sazawa, Kazuto; Nanayama, Yasuaki; Hata, Noriko; Taguchi, Shigeru; Sugawara, Kazuharu; Fukushima, Masami

2012-01-01

416

Comparative Studies on the Interfacial Behaviour of Adenylyl(3?—5?)Guanosine by Phase Sensitive AC Voltamhetry, Pulse Voltammetry and Single Sweep Voltahhetry at Charged Interfaces  

Microsoft Academic Search

Adeny ly 1-.(3?—5?)-guanosine has been investigated in order to expand the potentialities of pulse voltammetry and phase sensitive ac voltammetry in connection with the HMDE for study of the adsorption and interfacial behaviour of the investigated compound. The results are compared with rapid single sweep voltammetry being sensitive to the faradaic reduction response of the adsorbed substance. From the limiting

M. M. Kamal; Z. A. Ahmed; M. E. Ahmed; M. S. Ibrahim; Y. M. Temerk

1992-01-01

417

Anodic stripping voltammetry of arsenic(III) using gold nanoparticle-modified electrodes.  

PubMed

A novel method for the detection of arsenic(III) in 1 M HCl at a gold nanoparticle-modified glassy carbon electrode has been developed. The gold nanoparticles were electrodeposited onto the glassy carbon electrode via a potential step from +1.055 to -0.045 V vs SCE for 15 s from 0.5 M H2SO4 containing 0.1 mM HAuCl4. The resulting electrode surfaces were characterized with both AFM and cyclic voltammetry. Anodic stripping voltammetry of arsenic(III) on the modified electrode was performed. After optimization, a LOD of 0.0096 ppb was obtained with LSV. PMID:15456316

Dai, Xuan; Nekrassova, Olga; Hyde, Michael E; Compton, Richard G

2004-10-01

418

Electrochemistry in Media of Exceptionally Low Polarity: Voltammetry with a Fluorous Solvent  

PubMed Central

This work demonstrates the first cyclic voltammetry in a perfluorocarbon solvent without use of a cosolvent. The novel electrolyte tetrabutylammonium tetrakis[3,5-bis(perfluorohexyl)phenyl]borate (NBu4BArF104; 80 mM) allows for voltammetry of ferrocene in perfluoro(methylcyclohexane) by lowering the specific resistance to ?268 k cm at 20.8 °C. Despite significant solution resistance, the resulting voltammograms can be fitted quantitatively without difficulty. The thus determined standard electron transfer rate constant, k°, for the oxidation of ferrocene in perfluoro(methylcyclohexane) is somewhat smaller than for many solvents commonly used in electrochemistry, but can be explained readily as the result of the viscosity and size of the solvent using Marcus theory. Dielectric dispersion spectroscopy verifies that addition of NBu4BArF104 does not significantly raise the overall polarity of the solution over that of neat perfluoro(methylcyclohexane).

Olson, Eric J.; Boswell, Paul G.; Givot, Bradley L.; Yao, Letitia J.; Buhlmann, Philippe

2009-01-01

419

Electrochemistry in Media of Exceptionally Low Polarity: Voltammetry with a Fluorous Solvent.  

PubMed

This work demonstrates the first cyclic voltammetry in a perfluorocarbon solvent without use of a cosolvent. The novel electrolyte tetrabutylammonium tetrakis[3,5-bis(perfluorohexyl)phenyl]borate (NBu(4)BArF(104); 80 mM) allows for voltammetry of ferrocene in perfluoro(methylcyclohexane) by lowering the specific resistance to ?268 k cm at 20.8 °C. Despite significant solution resistance, the resulting voltammograms can be fitted quantitatively without difficulty. The thus determined standard electron transfer rate constant, k°, for the oxidation of ferrocene in perfluoro(methylcyclohexane) is somewhat smaller than for many solvents commonly used in electrochemistry, but can be explained readily as the result of the viscosity and size of the solvent using Marcus theory. Dielectric dispersion spectroscopy verifies that addition of NBu(4)BArF(104) does not significantly raise the overall polarity of the solution over that of neat perfluoro(methylcyclohexane). PMID:20212920

Olson, Eric J; Boswell, Paul G; Givot, Bradley L; Yao, Letitia J; Bühlmann, Philippe

2010-02-15

420

Direct reversible voltammetry and electrocatalysis with surface-stabilised Fe 2O 3 redox states  

Microsoft Academic Search

Nanoparticle film voltammetry is employed to explore the presence and reactivity of surface-stabilised iron redox centers at the interface of immobilised Fe2O3 nanoparticles of ca. 4nm diameter and aqueous buffer media. Mesoporous films of Fe2O3 nanoparticles on tin-doped indium oxide (ITO) substrates are formed in a layer-by-layer deposition process from aqueous colloidal Fe2O3 and aqueous cyclohexyl-hexacarboxylate followed by thermal (500°C)

Charles Y. Cummings; Michael J. Bonné; Karen J. Edler; Matthew Helton; Anthony McKee; Frank Marken

2008-01-01

421

Phase-structure analysis of brass by anodic linear-sweep voltammetry  

Microsoft Academic Search

Anodic linear-sweep voltammetry (ALSV) was applied to electrodeposited alloy layers and to metallurgically obtained Cu-Zn alloys of different composition and structure. Metallurgically obtained samples covered the range of composition in which a, (a+ß), ß and (ß+?) intermediate phases were detected by X-ray. The ALSV of samples containing less than 30 wt % Zn exhibited a single peak at -0.08 to

J. Stevanovi?; L. J. Skibina; M. Stefanovi?; A. Despi?; V. D. Jovi?

1992-01-01

422

Signal enhancement in adsorptive stripping voltammetry of Pt by forced convection during the measurement step  

Microsoft Academic Search

Adsorptive stripping voltammetry (‘formazone-method’) is already known as one of the most sensitive methods for platinum analysis with a detection limit in the low picograms range. In this work, it is shown that the detection limit can be lowered even more by one order of magnitude to 0.2pg (=1fmol) Pt in 15mL electrolyte, corresponding to 68fmol\\/L, by applying forced convection

Günther Weber; Jürgen Messerschmidt

2005-01-01

423

Carbon fiber-polyaniline composites: Kinetics of electrodeposition of polyaniline onto carbon fibers by cyclic voltammetry  

Microsoft Academic Search

Homogeneous and uniform coatings of polyaniline were successfully deposited on carbon fibers by an aqueous electrodeposition technique using p-toluene sulfonic acid as the electrolyte. Electrochemical deposition of aniline was carried out by cyclic voltammetry in the potential range of ?0.2 V to 1.0 V versus saturated calomel electrode (SCE). The electrochemical deposition parameters such as the number of cycles, scan

Aydin Aykanat; Jude O. Iroh

2002-01-01

424

Simultaneous, selective detection of catecholaminergic and indolaminergic signals using cyclic voltammetry with treated micro-sensor  

Microsoft Academic Search

Selective and simultaneous voltammetric analysis of catechols and indoles in vivo and in vitro has until now been feasible only by means of ‘slow’ scanning methods (scan speed in tens of seconds) such as differential pulse (DPV) and differential normal pulse voltammetry in conjunction with electrically and\\/or chemically treated carbon-fiber micro-electrodes (mCFE). Faster electrochemical techniques, such as chronoamperometry and cyclic

Francesco Crespi; Tim G. England; David G. Trist

1995-01-01

425

Evaluation of kinetic parameters of uranyl acetate complexes in ethanolic solution by cyclic voltammetry  

Microsoft Academic Search

The complexation of uranyl ion with acetate ions was investigated in 20% ethanolic solution by using cyclic voltammetry. The\\u000a uranium formed 1:1 and 1:2 complexes with acetate ions. The values of log ?1 and log ?2 for uranyl acetate complexes were 2.05 ± 0.08 and 5.25 ± 0.06 respectively. The diffusion coefficient and heterogeneous rate\\u000a constants for the reduction of uranyl ion at hanging

A. S. A. Khan; R. Ahmed; M. L. Mirza

2010-01-01

426

Determination of saponin in sugar juices from sugar refining processes by stripping voltammetry  

Microsoft Academic Search

Saponins were determined as oleanolic acid in refined sugar and sugar juices from beet sugar refining processes by differential?pulse cathodic stripping voltammetry (DPCSV) at the hanging mercury drop electrode (HMDE) after acidic hydrolysis of the saponin. Measurements were performed on diluted samples at the mg\\/1 level without further pretreatment. The optimised procedure allowed the determination of saponin at the mg\\/kg

Daniel Sancho; Luis Debán; Rafael Pardo; Marisol Vega

2000-01-01

427

Application of abrasive stripping voltammetry in corrosion science. I. determination of the corrosion potentials of metals  

Microsoft Academic Search

The application of abrasive stripping voltammetry for the determination of the corrosion potential of metal powders is described.\\u000a Micro amounts of a metal are fixed on a paraffin-impregnated graphite electrode immersed in suitable electrolyte solutions\\u000a and polarization curves are recorded. The value of the corrosion potential is determined by Tafel analysis. The precision\\u000a of the method is ±0.5% (mean rel.

Ivan Žežula; Miriam Gálová

1999-01-01

428

Measurement of the redox speciation of iron in seawater by catalytic cathodic stripping voltammetry  

Microsoft Academic Search

Catalytic cathodic stripping voltammetry (CSV) preceded by adsorptive collection of complexes of 1-nitroso-2-napthol (NN) can be used to determine iron in seawater. It is shown here that iron(II) is effectively masked in the presence of 2,2-dipyridyl (Dp) so that iron(III) is measured selectively. The concentration of iron(II) is then calculated as the difference between the concentrations of reactive iron (FeR)

Martha Gledhill

1995-01-01

429

Characterization of Local pH Changes in Brain Using Fast-Scan Cyclic Voltammetry with Carbon Microelectrodes  

PubMed Central

Transient local pH changes in the brain are important markers of neural activity that can be used to follow metabolic processes that underlie the biological basis of behavior, learning and memory. There are few methods that can measure pH fluctuations with sufficient time resolution in freely moving animals. Previously, fast-scan cyclic voltammetry at carbon-fiber microelectrodes was used for the measurement of such pH transients. However, the origin of the potential dependent current in the cyclic voltammograms for pH changes recorded in vivo was unclear. The current work explored the nature of these peaks and established the origin for some of them. A peak relating to the capacitive nature of the pH CV was identified. Adsorption of electrochemically inert species, such as aromatic amines and calcium could suppress this peak, and is the origin for inconsistencies regarding in vivo and in vitro data. Also, we identified an extra peak in the in vivo pH CV relating to the presence of 3,4-dihydroxyacetic acid (DOPAC) in the brain extracellular fluid. To evaluate the in vivo performance of the carbon-fiber sensor, carbon dioxide inhalation by an anesthetized rat was used to induce brain acidosis induced by hypercapnia. Hypercapnia is demonstrated to be a useful tool to induce robust in vivo pH changes, allowing confirmation of the pH signal observed with FSCV.

Takmakov, Pavel; Zachek, Matthew K.; Keithley, Richard B.; Bucher, Elizabeth; McCarty, Gregory S.; Wightman, R. Mark

2010-01-01

430

Measurement of kinetically resolved vesicular dopamine uptake and efflux using rotating disk electrode voltammetry.  

PubMed

The vesicular monoamine transporter-2 (VMAT-2) sequesters cytoplasmic dopamine (DA) into vesicles for storage and subsequent release. VMAT-2 activity has traditionally been measured in small synaptic vesicles isolated from rat striatum by monitoring [3H] DA uptake and in cellular expression systems using fast scan cyclic voltammetry. This is the first report using rotating disk electrode (RDE) voltammetry to measure VMAT-2 DA uptake and efflux in small synaptic vesicles. DA uptake profiles followed mixed order kinetics with apparent zero order kinetics for the first 25 s and apparent first order kinetics thereafter. Vesicular DA uptake was temperature- and ATP-dependent and was blocked by the VMAT-2 inhibitor tetrabenazine. Initial velocities of DA uptake were kinetically resolved and displayed Michaelis-Menten kinetics with a Km and Vmax of 289 +/- 59 nM and 1.9 +/- 0.2 fmol/(s microg protein), respectively. Methamphetamine-induced DA efflux was blocked by tetrabenazine and kinetically resolved with an initial velocity of 0.54 +/- 0.08 fmol/(s microg protein). These results suggest that RDE voltammetry can be used to make kinetically resolved measurements of vesicular DA uptake and efflux and will allow the design of experiments that could reveal important information about the kinetics of VMAT-2 activity and its inhibition. PMID:16480775

Volz, Trent J; Hanson, Glen R; Fleckenstein, Annette E

2006-02-09

431

INTERACTIONS OF ALTERNATE HOSTS, LARVAL MOVEMENT, AND POST-EMERGENCE GRASS CONTROL: CURRENT DATA AND IMPLICATIONS FOR CORN ROOTWORM RESISTANCE MANAGEMENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

The registration of transgenic corn with resistance to corn rootworm larval feeding offers a viable alternative to insecticides for managing the most economically important insect pests of corn. Maintaining insect susceptibility to transgenic crops (resistance management) is in the interest of grow...

432

Current Status of Anti-Aging Medicine, Especially Involving Management of the Menopause, as a Component of Complementary and Alternative Medicine in Korea  

Microsoft Academic Search

95 Recently, many developing countries have had changes in the composition of population and have become aging societies. Therefore, anti-aging medicine which is believed to have beneficial effect on the risk factors of geriatric associated diseases has been paid much attention. Complementary and alternative medicine (CAM) has been widely accepted by the general population, and is consequently known to account

Hyun Jung Kim; Hoon Kim; Jung-Ho Shin; Seung-Yup Ku

2009-01-01

433

Perspectives on the Current State of Alternate Assessments Based on Modified Academic Achievement Standards: Commentary on "Peabody Journal of Education" Special Issue  

ERIC Educational Resources Information Center

|In this commentary on the "Peabody Journal of Education" special edition, the author addresses implications of the contributing articles to three central domains of interest to states engaged in or considering the development of an alternate assessment on modified academic achievement standards: (a) identifying an eligible student population, (b)…

Weigert, Susan

2009-01-01

434

Staining of wool using the reaction products of ABTS oxidation by laccase: synergetic effects of ultrasound and cyclic voltammetry.  

PubMed

The effects of ultrasound on 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonate) enzymatic oxidation by laccase (Trametes villosa) has been studied by means of cyclic voltammetry. The reaction was allowed to proceed in the presence of a piece of wool and the coloration depth of the wool fabric was measured by means of K/S. It was observed that cyclic voltammetry is influenced the dyeing process and higher K/S values were obtained when the cyclic voltammetry was combined with the ultrasonic irradiation. Moreover, the K/S value is the sum of the values obtained when the wool staining is done in just the presence of cyclic voltammetry or in just the presence of ultrasound. The results obtained on the indigo carmine decolourization gives information on the importance of controlling the amount of ABTS(+) formed during the ultrasonication process. PMID:16979370

Munteanu, Florentina-Daniela; Basto, Carlos; Gübitz, Georg M; Cavaco-Paulo, Artur

2006-09-18

435

The effect of external magnetic field on the remagnetization process in FeCuNbSiB\\/Al\\/FeCuNbSiB films induced by an alternating current  

Microsoft Academic Search

The alternating current induced remagnetization process in FeCuNbSiB\\/Al\\/FeCuNbSiB films is studied. The frequency spectra of the voltage arising in the pick-up coil wound around the sample are measured as a function of an external dc magnetic field. It is shown that the frequency spectra differ substantially for the transverse and longitudinal external magnetic field directions. For the transverse field, several

N A Buznikov; A S Antonov; A L Dyachkov; A A Rakhmanov

2004-01-01

436

Cyclic voltammetry of the uranyl ion in magnesium chloride electrolyte at a graphite electrode in weakly acidic and neutral solutions  

Microsoft Academic Search

Voltammetry of U(VI) at graphite electrodes in aqueous media containing magnesium chloride electrolyte consists of two chemically reversible major processes within the pH range 2.4 to 6.6. The dominant process at low pH is observed in the potential region of about 0 to [minus]0.3 V (vs. SCE) under conditions of cyclic voltammetry and is assigned to the reaction UO[sub 2][sup

R. E. Dueber; A. M. Bond; P. G. Dickens

1994-01-01

437

Identification of inorganic pigments from paintings and polychromed sculptures immobilized into polymer film electrodes by stripping differential pulse voltammetry  

Microsoft Academic Search

Inorganic pigments in paintings and polychromed sculptures are studied by cyclic voltammetry and differential pulse stripping voltammetry using micro-sample coatings in Paraloid B72-film modified electrodes. Characteristic cathodic and anodic differential pulse profiles were obtained in the +0.4 to ?1.0V vs. SCE potential range for different cadmium, copper, lead, mercury and zinc pigments used in traditional colour palettes. Under optimized conditions,

A Doménech-Carbó; M. T Doménech-Carbó; M Moya-Moreno; J. V Gimeno-Adelantado; F Bosch-Reig

2000-01-01

438

Assessing alternative drug control regimes  

Microsoft Academic Search

The debate over alternative regimes for currently illicit psychoactive substances focuses on polar alternatives: harsh prohibition and sweeping legalization. This study presents an array of alternatives that lies between these extremes. The current debate lacks an explicit and inclusive framework for making comparative judgments. In this study, we sketch out such a framework, as a reminder of possible policy levers

Robert MacCoun; Peter Reuter; Thomas Schelling

1996-01-01

439

Characterization of a 32 ?m diameter carbon fiber electrode for in vivo fast-scan cyclic voltammetry.  

PubMed

Carbon fiber electrodes (CFE) are commonly used for in vivo detection of catecholamines due to their excellent electrochemical properties and biocompatibility. Fast-scan cyclic voltammetry (FSCV) combined with CFEs permits the detection of catecholamines such as dopamine (DA) with high specificity and reliability. However, advances in neuroscience constantly demand sensors with greater sensitivities and selectivities. This study investigated an untreated CFE of 32 ?m diameter and 300 ?m exposed length for detection of DA using FSCV. Despite the larger area of the working electrode, we observed only a small increase in the background current in comparison with the commonly used CFE of 7 ?m diameter and 100 ?m exposed length. The sensitivity of the 32 ?m CFE was 9 times greater than that of the 7 ?m CFE. These larger electrodes exhibited good linearity and a 6 fold higher signal-to-noise ratio than 7 ?m CFEs in vitro. The 32 ?m CFE showed significantly better selectivity for DA in preference to 3,4-dihydroxyphenylacetic acid than the 7 ?m CFE and similar selectivity to the 7 ?m CFE for ascorbic and homovanillic acid. The electrodes displayed good temporal resolution and electrochemical stability in both in vitro and in vivo tests. PMID:22995525

Chadchankar, Heramb; Yavich, Leonid

2012-09-17

440

Redox magnetohydrodynamic enhancement of stripping voltammetry: toward portable analysis using disposable electrodes, permanent magnets, and small volumes.  

PubMed

The use of redox magnetohydrodynamics (MHD) to enhance the anodic stripping voltammetry (ASV) response of heavy metals has been investigated, with respect to achieving portability: disposable electrodes consisting of screen-printed carbon (SPC) on a low temperature co-fired ceramic (LTCC) substrate, small volumes, and permanent magnets. The analytes tested (Cd(2+), Cu(2+), and Pb(2+)) were codeposited on SPC with Hg(2+) to form a Hg thin film electrode. High concentrations of Fe(3+) were used to produce a high cathodic current which generates a significant Lorentz force in the presence of a magnetic field. This Lorentz force induces solution convection during the deposition step, enhancing the mass transport of analytes to the electrode and increasing their preconcentrated quantity in the mercury thin film. Therefore, larger ASV peaks and improved sensitivities are obtained, compared to analyses performed without a magnet. The effects on ASV signal of varying Hg(2+) concentration (0.10 and 1.0 mM), deposition time (10-600 s), and electrode surface roughness were investigated. In addition, analyses were performed using a real lake water matrix. By using the disposable LTCC-SPC working electrodes in small volumes (150 microL) and with small permanent magnets (0.78 T), peak areas were increased by 75% when compared to the signal obtained in the absence of a magnetic field. A limit of detection of 25 nM for Cd(2+) was observed with only a 1 min preconcentration time. PMID:17124540

Weston, Melissa C; Anderson, Emily C; Arumugam, Prabhu U; Narasimhan, Padhmodhbhava Yoga; Fritsch, Ingrid

2006-10-13

441

Effect of ohmic, mass-transfer, and kinetic resistances on linear-sweep voltammetry in a cylindrical-pore electrode  

SciTech Connect

Extracting quantitative kinetic information from linear-sweep voltammograms (LSV) on porous electrodes is more difficult than on planar electrodes since the electrode surface is not uniformly accessible to the bulk supply of reactant or the counterelectrode. In this paper the authors present a means to account for the effect of ohmic, mass-transfer, and kinetic resistances on LSV by modeling a pore in a porous matrix as a cylindrical-pore electrode, and solving the mass and charge conservation equations in the context of this geometry for the simple redox reaction O + ne{sup {minus}} {r equilibrium} R where both O and R are soluble species. Both analytical and numerical techniques are used to solve the governing equations. The calculated peak currents and potentials are correlated by simple-to-apply empirical formulas to the measurable parameters: sweep rate, concentration of the redox species, diffusion coefficient, conductivity of the electrolyte, and pore dimensions. Using the correlations, a methodology is established for determining if the redox reaction kinetics are irreversible or reversible (Nernstian). If the reaction is irreversible, it is shown how the standard rate constant and the transfer coefficient may be extracted from linear-sweep voltammetry data, or if the reaction is reversible, how the number of electrons transferred may be deduced.

Weidner, J.W.; Fedkiw, P.S. (Dept. of Chemical Engineering, North Carolina State Univ., Raleigh, NC (US))

1991-09-01

442

Interaction of ciprofloxacin with DNA studied by spectroscopy and voltammetry at MWCNT/DNA modified glassy carbon electrode.  

PubMed

The interaction of ciprofloxacin (Cf) with double-stranded DNA was studied by cyclic voltammetry, fluorescence emission spectroscopy, and UV-Vis spectroscopy. The presence of DNA results in a decrease in the current and a positive shift in the Cf oxidation peak indicates the intercalative interaction. The corresponding heterogeneous rate constant (k(s)) and the electron transfer coefficient (?) were calculated for free Cf and the bound Cf-DNA complex. The UV spectroscopic data confirmed the interaction between Cf and DNA is intercalative. Besides, the fluorescence emitted by Cf at 420 nm could be quenched in Britton-Robinson (B-R) buffer solution (pH 7.0, 0.04 mol L(-1)) when DNA was added. The mechanism of fluorescence quenching was a static quenching; the binding constant and numbers of binding sites were obtained from the Stern-Volmer plot. The calibration curve was found to be linear between F(0)/F and the DNA concentration is lied in the two dynamic ranges of 0.8-96.0 and 96.0-223 ?g mL(-1) with the detection limit of 0.33 ?g mL(-1). The method was efficaciously applied to analyze DNA in the serum sample. PMID:23200377

Fotouhi, Lida; Atoofi, Zeynab; Heravi, Majid M

2012-10-17

443

Cyclic voltammetry as a tool to estimate the effective pore density of an anodic aluminium oxide template  

NASA Astrophysics Data System (ADS)

In this study, a new method for measuring the pore density of a porous-type anodic aluminium oxide (AAO) using cyclic voltammetry (CV) is first proposed. AAO film can be referred to as a nano-honeycomb structure because the pore shape of AAO is similar to that of the honeycomb and its pore size is in the nanometre scale. Different CV behaviour could be observed for a platinum electrode with and without the AAO film on the electrode surface. To obtain the pore density from CV data, it is assumed that the decrease of current density has resulted from the decrease of the reactive area because of the presence of AAO film. At the same time, the separation of the redox peak potential, {\\opentri }E_{\\mathrm {p}} , is less than 60 mV since the diffusion is influenced greatly by the presence of the AAO film. The diffusion is completed through the nanoscale pores with the presence of the AAO film. The pore density calculated from CV data showed good agreement with that from SEM images.

Cui, Xiaoli; Zhao, Qiang; Li, Zhizhou; Sun, Ziying; Jiang, Zhiyu

2007-05-01

444

Wireless fast-scan cyclic voltammetry measurement of histamine using WINCS -- a proof-of-principle study  

PubMed Central

Histamine is among the most poorly understood biogenic amines, yet the histaminergic system spreads throughout the brain and has been implicated in functions as diverse as homeostasis and synaptic plasticity. Not surprisingly then, it has been linked to a number of conditions including minimally conscious state, persistent vegetative state, epilepsy, addiction, cluster headache, essential tremor, and Parkinson’s disease. We have previously reported that the Wireless Instantaneous Neurotransmitter Concentration Sensing (WINCS) system can monitor dopamine, serotonin, and adenosine using fast-scan cyclic voltammetry (FSCV). Here, we demonstrate the expanded capability of the WINCS system to measure histamine. The optimal FSCV waveform was determined to be a triangle wave scanned between ?0.4 and +1.4 V at a rate of 400 V/s applied at 10 Hz. Using this optimized FSCV parameter, we found histamine release was induced by high frequency electrical stimulation at the tuberomammillary nucleus in rat brain slices. Our results suggest that the WINCS system can provide reliable, high fidelity measurements of histamine, consistently showing oxidative currents at +1.3 V, a finding that may have important clinical implications.

Chang, Su-Youne; Jay, Taylor; Munoz, Joel; Kim, Inyong; Lee, Kendall H.

2012-01-01

445

CdTe nanocrystal-based electrochemical biosensor for the recognition of neutravidin by anodic stripping voltammetry at electrodeposited bismuth film.  

PubMed

CdTe quantum dots (QDs)-based electrochemical sensor for recognition of neutravidin, as a model protein, using anodic stripping voltammetry at electrodeposited bismuth film is presented. This biosensor involves the immobilization of the captured QDs conjugates which was dissolved with 1M HCl solution to release cadmium ions and metal components were quantified by anodic stripping voltammetry after a 3-min accumulation at -1.2V on bismuth-film electrode (BiFE) of the biotin, served as recognition element, onto the gold surface in connection with a cysteamine self-assembled monolayer. The modification procedure was characterized by electrochemical impedance spectroscopy and atomic force microscopy. We exploit QDs as labels for amplifying signal output and monitoring the extent of competition process between CdTe-labeled neutravidin and the target neutravidin for the limited binding sites on biotin. As expected for the competitive mechanism, the recognition event thus yields distinct cadmium stripping voltammetric current peak, whose response decreases upon increasing the level of target neutravidin concentrations. Under optimal conditions, the voltammetric response is highly linear over the range of 0.5-100 ngL(-1) neutravidin and the limit of detection is estimated to be 0.3 ngL(-1) (5 nM). Unlike earlier two-step sandwich bioassays, the present protocol relies on a one-step competitive assay, which is more accurate and sensitive, showing great promise for rapid, simple and cost-effective analysis of protein. PMID:18722762

Du, Dan; Ding, Jiawang; Tao, Yuan; Li, Haibing; Chen, Xi

2008-07-22

446

Electrochemical identification of corrosion products on historical and archaeological bronzes using the voltammetry of micro-particles attached to a carbon paste electrode.  

PubMed

An overview of the electrochemical method for the identification of microsampled corrosion products from historical and archaeological bronzes is reported. Two characteristic examples of long-term air and subterranean formed patinas and two artificial patinas formed on Cu-6%Sn bronze in sulphate and chloride solutions, were investigated in 0.1M HCl(aq) by means of the cyclic voltammetry of micro-particles attached to a carbon paste electrode. Patina constituent phases were identified by comparing the electrochemical parameters of the patina samples to those of reference compounds: CuO, Cu(2)O, SnO, SnO(2), CuCl, CuCl(2) x 2H(2)O and CuSO(4) x 5H(2)O. An identification scheme was suggested which may be applied to discern the various corrosion products of bronze based on electrochemical data (voltammetric peak potentials). The presence of two prevalent phases of sulphate and chloride patinas, CuSO(4) and CuCl, as well as the presence of Sn compounds was clearly indicated by the cyclic voltammetry of microparticles, in both, naturally and artificially formed samples. A comparison to the ATR-FTIR results revealed that the methods are complementary and that their simultaneous application could prove particularly valuable in drawing conclusions about the current shape and prospects of the conservation and restoration of bronze artefacts. PMID:20441970

Satovi?, D; Martinez, S; Bobrowski, A

2010-03-25

447

Pulse radiolysis and cyclic voltammetry studies of redox properties of phenothiazine radicals  

NASA Astrophysics Data System (ADS)

One-electron transfer equilibria between seven phenothiazines were characterized by pulse radiolysis, producing radical-cations via oxidation by Br2·- or (SCN)2·- radicals. The reduction potentials of the phenothiazine radicals were determined by cyclic voltammetry. As an independent check, the redox equilibrium between one phenothiazine and the redox indicator ABTS was investigated. The data establish phenothiazines as useful indicators for radical redox properties. However, there are potential problems of aggregation, additional reactions with Br-/Br2·- and reactivity of the radicals towards buffers or other nucleophiles.

Madej, Edyta; Wardman, Peter

2006-09-01

448

General theory of cathodic and anodic stripping voltammetry at solid electrodes: mathematical modeling and numerical simulations.  

PubMed

Theory is presented to describe the voltammetric signals associated with the stripping phase of stripping voltammetry at solid electrodes. Three mathematical models are considered, and the importance of the hemispherical diffusion associated with electrochemical dissolution of particles in the micrometer range is investigated. Model A considers a "monolayer" system where the coverage at a specific point cannot exceed a maximum value. Model B considers a thin layer of metal or metal oxide, but in contrast to model A, the maximum surface coverage is not restricted. Model C represents the stripping of a "thick layer" where the deposition is also unrestricted. PMID:17469796

Ward Jones, Sarah E; Chevallier, François G; Paddon, Christopher A; Compton, Richard G

2007-05-01

449

Alternating current losses in YBa{sub 2}Cu{sub 3}O{sub 7-x} coated conductors on technical substrates  

SciTech Connect

We report on measurements of the ac losses of YBa{sub 2}Cu{sub 3}O{sub 7-x} conductors on technical substrates. The samples are taken from conductors 1 m long produced with an ion beam assisted deposition step in the manufacturing process yielding 1 cm wide conductors with critical currents approaching 100 A at 77.4 K. The losses due to combinations of ac transport currents and ac magnetic fields were measured calorimetrically and the results compared to theoretical estimates. While the results of our measurements are similar to the theoretical estimates, there are some important differences in the qualitative behavior. (c) 2000 American Institute of Physics.

Ashworth, S. P. [Brookhaven National Laboratory, Materials Science Division, P.O. Box 5000, Upton, New York 11973-5000 (United States); Maley, M. [Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, California 93440 (United States); Suenaga, M. [Brookhaven National Laboratory, Materials Science Division, P.O. Box 5000, Upton, New York 11973-5000 (United States); Foltyn, S. R. [Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, California 93440 (United States); Willis, J. O. [Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, California 93440 (United States)

2000-09-01

450

Diclofenac sodium topical solution with dimethyl sulfoxide, a viable alternative to oral nonsteroidal anti-inflammatories in osteoarthritis: review of current evidence  

PubMed Central

Topical nonsteroidal anti-inflammatory drugs (NSAIDs) may offer a safer alternative to their oral counterparts for the management of osteoarthritis. Diclofenac sodium topical solution with dimethyl sulfoxide (TDiclo) was evaluated in five randomized, controlled trials and is indicated for treatment of the signs and symptoms associated with osteoarthritis of the knee. Three studies showed that TDiclo is superior to placebo and vehicle control with respect to pain, physical function, and perception of osteoarthritis symptoms. Two studies showed that benefits are similar to those of oral diclofenac, with one study demonstrating statistical equivalence. The most common adverse event associated with TDiclo in these studies was dry skin. Incidences of gastrointestinal adverse events and abnormal levels of liver enzymes were lower with TDiclo compared with oral diclofenac in active-controlled studies. Based on these studies, TDiclo represents a practical, evidence-based option for the management of osteoarthritis of the knee.

Fuller, Philip; Roth, Sanford

2011-01-01

451

Glyphosate detection with ammonium nitrate and humic acids as potential interfering substances by pulsed voltammetry technique.  

PubMed

Pulsed voltammetry has been used to detect and quantify glyphosate on buffered water in presence of ammonium nitrate and humic substances. Glyphosate is the most widely used herbicide active ingredient in the world. It is a non-selective broad spectrum herbicide but some of its health and environmental effects are still being discussed. Nowadays, glyphosate pollution in water is being monitored but quantification techniques are slow and expensive. Glyphosate wastes are often detected in countryside water bodies where organic substances and fertilizers (commonly based on ammonium nitrate) may also be present. Glyphosate also forms complexes with humic acids so these compounds have also been taken into consideration. The objective of this research is to study the interference of these common pollutants in glyphosate measurements by pulsed voltammetry. The statistical treatment of the voltammetric data obtained lets us discriminate glyphosate from the other studied compounds and a mathematical model has been built to quantify glyphosate concentrations in a buffer despite the presence of humic substances and ammonium nitrate. In this model, the coefficient of determination (R(2)) is 0.977 and the RMSEP value is 2.96×10(-5) so the model is considered statistically valid. PMID:24054650

Martínez Gil, Pablo; Laguarda-Miro, Nicolas; Camino, Juan Soto; Peris, Rafael Masot

2013-06-25

452

A Technique and Device for Studying Alternating-Current Discharge Dynamics. Stratification of a Discharge in an Argon Flow at Atmospheric Pressure  

Microsoft Academic Search

The technique for studying discharge emission dynamics by high-speed photoregistration methods is based on self-tuning of the frequency (44 kHz) and phase of the discharge-supplying generator current to the rotational frequency of the mirror of a high-speed camera, the ratio of these frequencies being equal to 40 : 1. This technique has revealed that the discharge in a system with

G. N. Churilov; V. A. Lopatin; P. V. Novikov; N. G. Vnukova

2001-01-01

453

Complementary/Alternative therapies for the treatment of breast cancer. A systematic review of randomized clinical trials and a critique of current terminology.  

PubMed

The objectives of this study was to evaluate and critically analyze all randomized clinical trials (RCTs) of ''alternative cancer cures'' (ACCs) for breast cancer. The electronic databases Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Allied and Complementary Medicine, Scirus, BIOSIS, CancerLit and CINAHL and for ongoing trials the MetaRegister at http://www.controlled-trials.com/ and the National Research Register at http://www.update-software.com/national/ were searched from their inception. Bibliographies of located studies were scanned. Unpublished or ongoing trials were identified through correspondence with experts in the field. Our own files were hand searched for further RCTs. Review methods included a systematic review of RCTs involving breast cancer patients treated with ACCs, survival, parameters indicative of tumor burden, disease progression, cancer recurrence, and cancer cure. Results were tabulated and summarized. Thirteen RCTs met the inclusion criteria. In most cases their methodological quality is low, with only two RCTs scoring ''4'' and four RCTs scoring ''3'' out of 5 possible points for methodological quality. The treatments tested included various methods of psychosocial support such as group support therapy, cognitive behavioral therapy cognitive existential group therapy, a combination of muscle relaxation training and guided imagery, the Chinese herbal remedy Shi Quan Da Bu Tang, thymus extract, transfer factor, melatonin, and factor AF2. Encouraging but not fully convincing results emerged for melatonin. PMID:17238981

Ernst, Edzard; Schmidt, Katja; Baum, Michael

454

Photocatalytic degradation of flexible PVC\\/TiO 2 nanohybrid as an eco-friendly alternative to the current waste landfill and dioxin-emitting incineration of post-use PVC  

Microsoft Academic Search

Photo-degradable poly(vinyl chloride) (PVC)\\/titanium dioxide (TiO2) nanohybrid has been investigated to be utilized as an eco-friendly alternative strategy to the current waste landfill and toxic byproduct-emitting incineration of PVC wastes. Thus, the present study suggests a novel idea related to preparing the photocatalytically degradable nanohybrid through TiO2 nanoparticle-integrated hyperbranched poly(?-caprolactone) (HPCL–TiO2). The main aim of this study is to find

Sung Ho Kim; Seung-Yeop Kwak; Takenori Suzuki

2006-01-01

455

Note: Measuring breakdown characteristics during the hot re-ignition of high intensity discharge lamps using high frequency alternating current voltage  

NASA Astrophysics Data System (ADS)

To investigate the cold and hot re-ignition properties of High Intensity Discharge (HID) lamps in more detail an automated setup was designed in such a way that HID lamps of various sizes and under different background pressures can be tested. The HID lamps are ignited with a ramped sinusoidal voltage signal with frequencies between 60 and 220 kHz and with amplitude up to 7.5 kV. Some initial results of voltage and current measurements on a commercially available HID lamp during hot and cold re-ignition are presented.

van den Bos, R. A. J. M.; Sobota, A.; Manders, F.; Kroesen, G. M. W.

2013-04-01

456

Electrochemical investigations of electronically conductive polymers. 2. Evaluation of charge-transport rates in polypyrrole using an alternating current impedance method  

SciTech Connect

An ac impedance method was used to determine apparent diffusion coefficients associated with the oxidation of polypyrrole. This method was applied to the reduced (nonconductive) form of the polymer, and the polymer remained in the nonconductive state throughout the duration of the experiment. Apparent diffusion coefficients obtained were similar in magnitude to coefficients obtained by a related current-pulse method. Diffusion coefficients obtained from finite diffusion data were ca. a factor of 3.4 times larger than coefficients obtained from semiinfinite diffusion data.

Penner, R.M.; Martin, C.R. (Texas A and M Univ., College Station (USA))

1989-01-26

457

Fluid Modeling of a Nitrogen Atmospheric-Pressure Planar Dielectric Barrier Discharge Driven by a Realistic Distorted Sinusoidal Alternating Current Power Source  

NASA Astrophysics Data System (ADS)

One-dimensional self-consistent simulations of a parallel-plate atmospheric-pressure nitrogen dielectric barrier discharge (DBD) are presented. The DBD was driven by a realistic distorted-sinusoidal voltage power source with a frequency of 60 kHz. The simulated discharge currents are in quantitative agreement with experimental measurements. N4+ ions gain more of the input electric power than electrons, which is unlike most glow discharges. The densities of all charged and neutral species increase exponentially with increasing applied peak voltage in the range of 6.2--8.6 kV. The higher the permittivity of the dielectric material, the larger the discharge current and the longer the period of gas breakdown. In addition, the quantity of accumulated charges at each electrode increases with increasing permittivity of the dielectric material. Finally, the increase in dielectric thickness from 1.0 to 2.0 mm greatly reduces the densities of all species and also the plasma absorbed by the power.

Cheng, Kai-Wen; Hung, Chieh-Tsan; Lin, Kun-Mo; Chiu, Yuan-Ming; Wu, Jong-Shinn; Yu, Jen-Perng

2012-11-01

458

Alternative laser system for cesium magneto-optical trap via optical injection locking to sideband of a 9-GHz current-modulated diode laser.  

PubMed

By optical injection of an 852-nm extended-cavity diode laser (master laser) to lock the + 1-order sideband of a ~9-GHz-current-modulated diode laser (slave laser), we generate a pair of phase-locked lasers with a frequency difference up to ~9-GHz for a cesium (Cs) magneto-optical trap (MOT) with convenient tuning capability. For a cesium MOT, the master laser acts as repumping laser, locked to the Cs 6S?/? (F = 3) - 6P?/? (F' = 4) transition. When the + 1-order sideband of the 8.9536-GHz-current-modulated slave laser is optically injection-locked, the carrier operates on the Cs 6S?/? (F = 4) - 6P?/? (F' = 5) cooling cycle transition with -12 MHz detuning and acts as cooling/trapping laser. When carrying a 9.1926-GHz modulation signal, this phase-locked laser system can be applied in the fields of coherent population trapping and coherent manipulation of Cs atomic ground states. PMID:22453427

Diao, Wenting; He, Jun; Liu, Zhi; Yang, Baodong; Wang, Junmin

2012-03-26

459

Catalytic adsorptive stripping voltammetry versus electrothermal atomic absorption spectrometry in the determination of trace cobalt and chromium in human urine.  

PubMed

Two methods of the determination of cobalt and chromium in human urine of non-occupationally exposed populations-highly sensitive catalytic adsorptive stripping voltammetry (CAdSV) and electrothermal atomic absorption spectrometry (ET-AAS)-are evaluated and compared. The CAdSV methods are based on adsorptive accumulation of a cobalt-nioxime (1,2-cyclohexanedione dioxime) or a chromium-DTPA (diethylenetriammine-N,N,N',N'',N''-pentaacetic acid) complexes on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of the catalytic reduction current of the adsorbed complex in the presence of sodium nitrite in case of cobalt or in the presence of sodium nitrate in case of chromium determination. In the CAdSV procedure UV-photolysis was used for the sample pre-treatment; the ET-AAS determination did not require any separate preliminary decomposition of the analyte urine samples. The accuracy of the procedures was checked by the analysis of commercially available quality control urine samples. The detection limits (3sigma) were 0.13mugl(-1) for Co and 0.18mugl(-1) for Cr in ET-AAS determination and 0.007mugl(-1) for Co and 0.002mugl(-1) for Cr in CAdSV measurements. Precision (R.S.D.) was less than 5% for both methods. The study has shown that the CAdSV is a more reliable and sensitive technique for the determination of very low cobalt and chromium contents in urine, the detection of which is not possible when using the AAS technique. PMID:18970083

Husáková, L; Bobrowski, A; Srámková, J; Królicka, A; Vytras, K

2005-05-15

460

Anodic Voltammetry of Thioacetamide and its Amperometric Determination in Aqueous Media  

PubMed Central

TAA is a harmful, presumptive pollutant in tap waters and waste waters. Several alternatives have been tested as new possibilities for the anodic determination of TAA in aqueous solutions, simulated waste waters and tap water. The electrochemical behaviour of thioacetamide (TAA) was investigated at a boron-doped diamond (BDD) electrode both in unbuffered 0.1 M Na2SO4 and buffered solutions as supporting electrolytes. The anodic oxidation of TAA showed well-defined limiting currents or current peaks and a good linearity of the amperometric signal vs. concentration plots. The analytical parameters of sensitivity, RSD and LOD, obtained under various experimental conditions, suggest the suitability of the BDD electrode for electroanalytical purposes. Low fouling effects, good reproducibility and stability, as well as the sharpness of the amperometric signals in both unbuffered/ buffered acidic or neutral media, highly superior to those obtained using a glassy carbon (GC) electrode, recommend the unmodified BDD electrode as a promising potential amperometric sensor for environmental applications, regarding the direct anodic determination of TAA in aqueous media.

Cinghita, Dan; Radovan, Ciprian; Dascalu, Daniela

2008-01-01

461

Steady-state macroscale voltammetry in a supercritical carbon dioxide medium.  

PubMed

The electrochemical oxidation and reduction of decamethylferrocene is demonstrated in supercritical carbon dioxide at a macro gold disc electrode at 100 bar and 313 K. Fast mass transport effects were exhibited and the corresponding steady-state voltammetry was observed at high scan rates. A highly lipophilic room temperature ionic liquid that readily dissolved in supercritical CO(2) with acetonitrile as a co-solvent was used as an electrolyte, allowing for a conducting supercritical single phase. Experimental observations along with simulation results confirmed the hypothesis that a thin layer of liquid-like phase of co-solvent is formed at the electrode surface and is restricted by a more supercritical phase of high natural convection and bulk concentration. PMID:23212608

Toghill, Kathryn E; Voyame, Patrick; Momotenko, Dmitry; Olaya, Astrid J; Girault, Hubert H

2013-01-21

462

Cyclic voltammetry: a new strategy for the evaluation of oxidative damage to bovine insulin.  

PubMed

Research on protein oxidative damage may give insight into the nature of protein functions and pathological conditions. In this work, the oxidative damage of bovine insulin on Au electrode was investigated by cyclic voltammetry (CV). The experimental results show that there are two anodic peaks for the oxidative damage of bovine insulin, which arise from the oxidation of the exposed disulfide bond S--S(CYS7A,CYS7B), forming sulfenic acid RSOH (1.20 V, vs. SCE), sulfinic acid RSO(2)H and sulfonic acid RSO(3)H (1.35 V, vs. SCE). These in vitro findings not only demonstrate the applicability of CV in simulating/evaluating the oxidative damage of nonredox proteins but also find two promising candidates (two anodic peaks) for measuring insulin. PMID:20027620

Zong, Wansong; Liu, Rutao; Sun, Feng; Wang, Meijie; Zhang, Pengjun; Liu, Yihong; Tian, Yanmin

2010-02-01

463

Development of anodic stripping voltammetry for determination of gallium in U Ga alloy  

NASA Astrophysics Data System (ADS)

Deposition potential, deposition time, square-wave frequency, rotation speed of the rotating disc electrode and gallium concentration have been studied in detail, for trace concentration level determination of gallium metal in U Ga alloy by square-wave voltammetry anodic stripping analysis, in 1 M NaClO4 + 0.5 M NaSCN at mercury film electrode (MFE). Optimum conditions have been found for Ga(III) determination by obtaining calibration graphs for the range 1 10 × 10-7 M gallium. Error and standard deviation less than 1% were assessed of this method with all gallium standard solutions. The developed methodology was applied successfully as a subsidiary method for the determination of gallium content in synthetic U Ga samples with very good precision and accuracy (under 1% error and std. dev.).

Bhardwaj, T. K.; Sharma, H. S.; Aggarwal, S. K.

2007-03-01

464

Quantitative roughness characterization and 3D reconstruction of electrode surface using cyclic voltammetry and SEM image  

NASA Astrophysics Data System (ADS)

Area measurements from cyclic voltammetry (CV) and image from scanning electron microscopy (SEM) are used to characterize electrode statistical morphology, 3D surface reconstruction and its electroactivity. SEM images of single phased materials correspond to two-dimensional (2D) projections of 3D structures, leading to an incomplete characterization. Lack of third dimension information in SEM image is circumvented using equivalence between denoised SEM image and CV area measurements. This CV-SEM method can be used to estimate power spectral density (PSD), width, gradient, finite fractal nature of roughness and local morphology of the electrode. We show that the surface morphological statistical property like distribution function of gradient can be related to local electro-activity. Electrode surface gradient micrographs generated here can provide map of electro-activity sites. Finally, the densely and uniformly packed small gradient over the Pt-surface is the determining criterion for high intrinsic electrode activity.

Dhillon, Shweta; Kant, Rama

2013-10-01

465

Charge transfer in porphyrin-calixarene complexes: ultrafast kinetics, cyclic voltammetry, and DFT calculations.  

PubMed

Transient absorption spectroscopy, cyclic voltammetry, and DFT calculations were used to describe charge transfer processes in a series of 5,10,15,20-tetrakis(N-methylpyridinium-n-yl) porphyrins (TMPyPn, n = 4,3,2) and TMPyPn/p-sulfonatocalix[m]arene (clxm, m = 4,6,8) complexes. Excitation of TMPyPn is accompanied by an increasing electron density at the methylpyridinium substituents in the order TMPyP2 < TMPyP3 < TMPyP4. The quenching of the excited singlet states of the complexes increases with the number of ionized phenolic groups of clxm and can be correlated with the partial transfer of the electron density from O(-) to the peripheral methylpyridinium substituents rather than to the porphyrin ring. PMID:21399801

Kubát, Pavel; Šebera, Jakub; Záliš, Stanislav; Langmaier, Jan; Fuciman, Marcel; Polívka, Tomáš; Lang, Kamil

2011-03-11

466

An expert consortium review of the EC-commissioned report "alternative (Non-Animal) methods for cosmetics testing: current status and future prospects - 2010".  

PubMed

The European cosmetics legislation foresees a review in 2011 and possible postponement of the 2013 marketing ban to enforce the testing ban for systemic and repeated-dose animal tests. For this purpose, a 119-page report commissioned by the European Commission was published recently. Here, a group of 17 independent experts from the US, Europe, and Japan was brought together to evaluate the report. The expert panel strongly endorsed the report and its conclusions. A number of important options not considered were identified; these do not, however, affect the overall conclusions regarding the current lack of availability of a full replacement, especially for the areas of repeated dose toxicity, carcinogenicity testing, and reproductive toxicity, though a roadmap for change is emerging. However, some of these options may provide adequate data for replacement of some animal studies in the near future pending validation. Various recommendations expand the original report. The reviewers agree with the report that there is greater promise in the short term for the areas of sensitization and toxicokinetics. Additional opportunities lie in more global collaborations and the inclusion of other industry sectors. PMID:21993956

Hartung, Thomas; Blaauboer, Bas J; Bosgra, Sieto; Carney, Edward; Coenen, Joachim; Conolly, Rory B; Corsini, Emanuela; Green, Sidney; Faustman, Elaine M; Gaspari, Anthony; Hayashi, Makoto; Wallace Hayes, A; Hengstler, Jan G; Knudsen, Lisbeth E; Knudsen, Thomas B; McKim, James M; Pfaller, Walter; Roggen, Erwin L

2011-01-01

467

Alternative fuels  

SciTech Connect

This paper presents the preliminary results of a review, of the experiences of Brazil, Canada, and New Zealand, which have implemented programs to encourage the use of alternative motor fuels. It will also discuss the results of a separate completed review of the Department of Energy's (DOE) progress in implementing the Alternative Motor Fuels Act of 1988. The act calls for, among other things, the federal government to use alternative-fueled vehicles in its fleet. The Persian Gulf War, environmental